Bluetooth Low Energy (BLE) has become a major wireless technology for the Internet of Things (IoT). Recent efforts of academia, industry and standards development organizations have focused on creating BLE mesh network solutions. 6BLEMesh is a specification being developed by the IETF that defines an IPv6-oriented approach for BLE mesh networking. In this paper, we perform an experimental evaluation of 6BLEMesh, based on a real implementation. We evaluate latency, round trip time (RTT) and energy consumption. For the latter, we model the device current consumption, we determine the energy efficiency of communication, and we obtain the theoretical device lifetime (for battery-operated devices), for three different hardware platforms. Under the assumptions in our study , the maximum, asymptotic, device lifetime is 573 days, whereas battery-operated router devices can also achieve 3-digit lifetimes (in days) in many scenarios. Our results also illustrate the impact on performance of BLE-level and application-level parameter settings, adaptation layer mechanisms such as IPv6 header compression, and device hardware characteristics. Bluetooth Low Energy (BLE) is a wireless communications technology created by the Bluetooth Special Interest Group (SIG), and introduced as part of the Bluetooth 4.0 core specification . In contOriginally, BLE only supported the star network topology. However, many competing technologies in the IoT space support the mesh network topology as well, which provides advantages in terms of robustness and covered area. While Bluetooth 4.1 removed the constraints that only allowed the star topology in BLE, no subsequent Bluetooth core specification defined how to enable end-to-end communication on a mesh topology. In parallel, many academic and proprietary proposals were designed in order to cope with this limitation .Industry and academic interest in BLE mesh networks triggered two standardization initiatives intended to enable BLE mesh networks, called Bluetooth Mesh ,9,10 andIn this paper, and to the best of our knowledge, we provide the first experimental evaluation of 6BLEMesh. We focus on latency, round trip time (RTT), and energy consumption. For the latter, we measure the performance differences of using different device hardware platforms, and develop models to predict crucial parameters, such as lifetime of battery-operated devices and energy efficiency of communication. In the conditions assumed in our study , the maximum device lifetime found is 573 days. Our results also illustrate the impact on performance of BLE-level and application-level parameter settings, along with device hardware characteristics.The remainder of this paper is organized as follows: 6BLEMesh specifies an IPv6-based solution for end-to-end communication in a BLE mesh network topology, by adapting IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs) . This seBLE is defined as a full protocol stack see . The BLEThe BLE Physical Layer defines 40 different frequency channels in the 2.4 GHz Industrial Scientific Medical (ISM) band. The channels are divided into three advertising channels and 37 data channels. The Physical Layer bit rate in Bluetooth 4.x specifications is 1 Mbit/s .connInterval time, the master sends a packet to the slave, initiating a packet exchange between both endpoints called connection event  fragmentation, (2) IPv6 and UDP header compression, and (3) IPv6 Neighbor Discovery (ND) optimization. The first mechanism allows complying with the IPv6 requirement that packets of at least 1280 bytes need to be supported by the layer below IPv6; note that maximum frame payload sizes in IEEE 802.15.4 are typically up to only ~100 bytes. The last two mechanisms enable lightweight operation in resource-constrained environments. Header compression in 6LoWPAN produces efficient header encoding prior to packet transmission, whereas 6LoWPAN-optimized ND minimizes multicast operation and allows energy-constrained devices to remain most of the time in a low energy consumption state.6LoWPAN Border Router (6LBR): it is an edge router that connects the 6LoWPAN network with the Internet. It often supports several network interfaces, including one used for communication with the 6LoWPAN network, and at least another one that offers Internet connectivity .6LoWPAN Node (6LN): it is an end-device, without routing capabilities. 6LNs are typically simple devices with restricted energy sources . They may be directly connected to a 6LR or a 6LBR.6LoWPAN Router (6LR): it is an internal 6LoWPAN network router. It typically relays packets originated at, or intended for, a 6LN.IEEE 802.15.4 supports the mesh topology. Accordingly, 6LoWPAN defines three node types to handle the described operation in such topology:In 2015, the IETF published RFC 7668, which specifies IPv6 over BLE networks by leveraging 6LoWPAN functionality . However6BLEMesh restores the 6LR role for intermediate routers in multihop topologies.6BLEMesh restores also the multihop functionality supported in 6LoWPAN-optimized ND, including Duplicate Address Detection (DAD) centralized at the 6LBR.A modified header compression mechanism is specified in 6BLEMesh. RFC 7668 fully omitted the source IPv6 address of a packet sent by a 6LN, since the 6LBR knows the source of packets received via a given BLE connection. Similarly, the destination IPv6 address packets sent to a 6LN was omitted as well. However, since 6BLEMesh targets a multihop scenario, such optimization can only be applied in the first/last link, i.e. a link where a 6LN is an endpoint.For end-to-end communication, 6BLEMesh requires a route-over routing solution, which is not specified and can thus be selected by implementers accordingly to scenario requirements.In order to expand the range of supported BLE topologies, the IETF IPv6 over Networks of Resource-constrained nodes (6Lo) working group has been developing a new standard, called 6BLEMesh, which aims to carry IPv6 packets over BLE networks that use the mesh topology . To thisNote that, in 6BLEMesh, devices may be more complex than RFC 7668 ones, since in 6BLEMesh a device may run both the master and the slave roles simultaneously.This section overviews the literature in the topics related with this paper, that is, BLE mesh networking, with a focus on performance evaluation of standardized BLE mesh network solutions, including 6BLEMesh.The section is organized in three subsections. The first one introduces and discusses the main categories of BLE mesh networking proposals. The second subsection reviews Bluetooth Mesh studies. The last subsection discusses work related with or influenced by 6BLEMesh. Note that, since 6BLEMesh is a novel standardized solution, still being completed as of the writing, the body of related literature is still narrow, currently.Before the publication of the Bluetooth Mesh standard, authors in  collecteAcademic, non-standards-based, BLE mesh networking solutions have recently been created as well ,36,37. HBluetooth Mesh and 6BLEMesh were comprehensively investigated and compared in . The worWhile Bluetooth Mesh is a relatively recent standard, several published studies have already evaluated it in terms of different performance parameters.One of the first Bluetooth Mesh standard evaluation studies focused on latency performance . Its autThe authors in  providedAnother work evaluated analytically the effect of different network settings on network reliability, delay and scalability . The autA smart office use case was proposed in , where tThe authors in  challengIn  the authThe feasibility of using Bluetooth Mesh for indoor localization systems has also been studied . The autFinally, a smart home solution based on Bluetooth Mesh has been developed , by usinThere exist few research works on IPv6-based BLE mesh networking, either focusing on 6BLEMesh or following an independent approach.Use of a parametrization layer was introduced by the authors of the BLEach implementation of IPv6 over BLE . They arThe authors in  experimeAnother approach to support IPv6-based BLE mesh networking was based on emulating a 6LoWPAN network  on top of Bluetooth Mesh  IPv6 funA new Neighbor Discovery (ND) approach for 6BLEMesh was proposed in . AuthorsAs of the writing of this article, to our best knowledge, no prior published work provides an experimental evaluation of 6BLEMesh.In order to evaluate 6BLEMesh experimentally, we developed a three-node prototype testbed that comprises a 6LN, a 6LR, and a 6LBR a. TherefOn the other hand, the experiments performed by using this testbed may also represent a reference to understand or estimate performance results in more complex scenarios see .We implemented the different roles on Texas Instruments CC2650 platforms  , includiWe implemented 6BLEMesh by modifying and extending an RFC 7668-compliant implementation called BLEach , which rWe conduct two types of delay-related evaluations on the testbed described in We measure one-hop latency as the total time required for sending an IPv6 packet to a sender’s one-hop neighbor. We consider two cases: (1) the sender is also the packet source, and (2) the sender just relays the packet. In the first case, we study the latency of packet transmission from the 6LN to the 6LR. In the second one, we evaluate the latency of packet transmission between the 6LR and the 6LBR.connInterval duration. Thus, the expected time to actually send an IPv6 packet from the sender node is connInterval/2, plus the packet transmission time. However, if occasionally the IPv6 packet cannot be delivered during the current connection interval, it will be delivered in subsequent connection intervals.From an analytical point of view, the IPv6 packet may be sent at any time during the current connection interval, of connInterval set to 125 ms. The measured latency shown in connInterval plus the Contiki tick clock time of the 6LN in our testbed, which is 7.813 ms . For each subsequent packet sent, latency decreases from the previous packet latency by a delay, denoted δ, of 1–2 tick clock periods, as the actual packet generation and handling is delayed by that time. The time since packet generation until the next connection event decreases steadily for a cycle of 11–12 packets, until a packet needs to wait again for a full connInterval for the next connection event. The described behavior repeats again thereafter, leading to the sawtooth shape shown in connInterval, and a cycle only comprises three packets. As shown in δ). However, packet 4 is generated too late to be sent at the beginning of its current connInterval, thus it is sent at the beginning of the subsequent connInterval, increasing latency again and starting a new cycle.connInterval setting  as in the previous experiment. The measured latency shown in The previous study was carried out on a network where the sender was also the IPv6 packet source. We next also study the one-way packet transmission latency between two neighboring nodes where the sender is not the IPv6 packet source; instead, the sender , and typically equal to connInterval (when the sender is a relay). However, for connInterval of 4 s, the packet sending interval (of 1 s) is lower than connInterval. For this setting, the minimum and the average RTT latency increase, which we attribute to node queuing delay. An additional comment is that we observed packet drops, in general, when the time between consecutive packets exceeded connInterval, due to memory overflow events.Results show that, when As introduced in earlier sections, there are three node roles in 6BLEMesh: the 6LN, the 6LR, and the 6LBR. The last two, being routers, are better suited for devices with a good energy supply . However, the 6LN is expected to be an energy-constrained device, e.g., running on a simple battery as its energy source.In this section, we model the 6LN current consumption, and we evaluate important energy-related performance parameters.First, we study the current consumption of a 6LN in two situations: (1) in a connection interval without actual user data transmission , and (2) in a connection interval wherein the device transmits one IPv6 data packet  every connection interval. These measurements allow us to derive a 6LN current consumption model. Then, we study the energy efficiency that corresponds to different data packet transmission intervals, and the device lifetime of the considered device types for different data transmission intervals. Finally, we evaluate the energy performance improvement of 6BLEMesh IPv6 header compression.Since different hardware platforms exhibit different current consumption characteristics, our model is created, and evaluations are performed, considering three popular commercial BLE device platforms: (1) Nordic Semiconductor PCA10028   . This variable can be obtained by using Equation (1):Based on the current consumption characterization shown in iT and iI represent the state durations and corresponding current consumptions shown in T1 which is denoted Sleep-NDT). The latter can be computed by using Equations (2) and (3), where CIT refers to connInterval and ND-activeT denotes the sum of the active time parts within connInterval:All values of connInterval settings, is depicted in connInterval, since the influence of sleep intervals increases. For example, when connInterval is set to 50 ms, the average current consumptions of PCA10028, LaunchPad and SensorTag are 0.181, 0.395 and 0.290 mA, respectively, whereas for connInterval equal to 4 s, the respective average consumptions are 0.017, 0.018 and 0.022 mA. Note that, in state 2 . This variable can be obtained by using Equation (4):We next calculate the average current consumption of a slave device in a BLE connection with actual data packet transmission (denoted iT and iI in (4) represent the state durations and corresponding current consumptions shown in Sleep-WDT). The latter can be determined based on Equations (5) and (6), where WD-activeT refers to the sum of active time parts within connInterval when an IPv6 packet is sent:The values of connInterval settings, is depicted in connInterval lower than 1 s, LaunchPad consumes more current, while otherwise SensorTag shows a greater current consumption. Curves in The average current consumption of a slave, when a data packet is actually transmitted, for the considered devices, and for different connInterval.) As shown in Device current consumption during connection intervals with and without data packet transmission were characterized in detail in DataPacketE is the energy that is consumed to deliver one data packet, and PayloadL is the user payload length of that data packet . DataPacketE can be obtained by using Equation (8):In this section, we study the energy efficiency of communication, based on the energy modeling provided in the previous subsection. The energy efficiency per conveyed byte of user data through a BLE connection is calculated by using Equation (7):DIT), there may be connection intervals without actual data transmission, along with one data connection interval. We take this into consideration in order to compute the average current consumption, denoted AvgI. The voltage assumed is 3 V, as required by the BLE devices considered in this work. AvgI can be obtained as shown in Equation (9):NoData-CII and Data-CII can be obtained by using Equations (1) and (4), respectively.Within a data interval  indicates how the 6LN device lifetime, denoted L, is computed. BatteryE represents the total energy capacity of the battery, whereas AvgI denotes the average current consumption of the 6LN. Note that the latter can be obtained as shown in (9). We assume an BatteryE of 235 mAh, which is typical for a button cell battery:The device lifetime is an important performance parameter for a battery-operated device, as is typically a 6LN. In addition to the capacity of the energy source, device lifetime is affected by BLE and application-level settings that determine the average current consumption, including connInterval settings, and for different devices. In the figure, maximum lifetime curves correspond to the case where there is no data packet payload transmitted in any connection event. Minimum lifetime corresponds to CIT = DIT in our study, where we assume that all connection intervals involve the exchange of one packet carrying user data.connInterval is lower than 1 s, due to the lower sleep mode current consumption of SensorTag discussed earlier. The maximum lifetime is 420 days, 296 days and 300 days for PCA10028, LaunchPad and SensorTag, respectively, when connInterval is set to 1 s. The overall maximum lifetime is 573 days, which happens for PCA10028 when connInterval is set to 4 s, while the minimum lifetime is ~16 days, which occurs for LaunchPad when connInterval is set to 50 ms.connInterval and data interval settings, and for the considered devices. connInterval. This confirms that the data interval setting has no significant impact on the device lifetime, in contrast with the connInterval setting, which is expected to be smaller than or equal to the data interval.One of the challenges to efficiently support IPv6 in IoT environments is the relatively large IPv6 header . Transmission and reception operations consume a significant amount of energy. In addition, a large IPv6 header contributes to fragmentation, as the BLE Link Layer supports a relatively short maximum payload size (of 23 bytes in Bluetooth 4.1). As introduced in connInterval, and lifetime of a 6LN device. The PCA10028 device hardware platform is assumed for the 6LN.This subsection illustrates the impact of 6BLEMesh IPv6 header compression on current consumption, energy consumption over In our measurements in CIT = DIT for simplicity, when a compressed IPv6 packet of 58 bytes is transmitted with and without IPv6 header compression. connInterval, for different connInterval settings. The relative impact of header compression increases as connInterval decreases, since header compression benefits arise only for transmission intervals . For the lowest connInterval setting considered , header compression reduces the average current consumption by a factor of 1.91. For a connInterval of 4 s, header compression decreases the average current consumption by a factor of 1.12.connInterval, with and without header compression. As shown in the figure, header compression allows to extend the device lifetime significantly. Consistently with connInterval. However, even for connInterval = 4 s, device lifetime increase  is significant.In this section, we use the current consumption models derived in the previous section to investigate the feasibility of supporting energy-constrained  6LRs in 6BLEMesh. Note that many mesh topology deployments in IoT require intermediate devices to be always on, in order for such devices to be able to receive and forward packets at any time. However, this limits the applicability of such deployments to scenarios where intermediate devices have a virtually unlimited energy source .6BLEMesh might exploit the intrinsic TDMA approach of BLE in order to support energy-constrained 6LRs. A 6LR needs to stay active for the packet exchange with each connected neighbor at the beginning of each connection event. However, a 6LR may remain in sleep mode otherwise.connInterval time, and the device lifetime of a battery-operated 6LR, by using the energy consumption model derived in the previous section. We consider a Nordic PCA10028 device as the hardware platform for the 6LR, running on a battery of 235 mAh, which is connected to N neighbors. We assume an optimized approach where the 6LR communicates with all its neighbors consecutively by, first, waking up (state 9), then participating in the packet exchange with each one of its neighbors (states 10 and 11 for each neighbor), and finally going through postprocessing, radio off and cool down  before returning to sleep state, and staying in such state until the beginning of the connection interval. We study how the indicated performance parameters vary as a function of connInterval, and of the number of neighbors N, and whether actual data packet transmission takes place  or not.We next investigate the current consumption, the energy consumption over a connInterval, since sleep intervals become dominant. Relative differences among the considered settings decrease as well. The current consumption difference between sending one data packet every connInterval via each connection of the 6LR, and never sending a data packet, increases with the number of neighbors of the 6LR. connInterval. For N = 10, connInterval = 4 s, and CIT = DIT, the 6LR consumes roughly 14% more energy over a connInterval than in absence of data packet transmission.connInterval settings , or a low number of connected neighbors  and connInterval ≥ ~1 s. When network node density is high , the maximum theoretical lifetime of a battery-operated 6LR takes lies between 326 and 371 days. In some scenarios, it will be feasible to run a 6BLEMesh network comprising energy-constrained 6LRs, especially for high connInterval, infrequent data transmission and rather sparse networks.In this paper, we experimentally evaluated 6BLEMesh, an IPv6-based solution for BLE mesh networking that is currently being finalized by the IETF. As a side-contribution of the paper, we publicly offer our 6BLEMesh implementation, which comprises the 6LBR, 6LR and 6LN roles. In the evaluation, we focused on latency, RTT, and energy consumption as main performance parameters.connInterval), and the case where the sender relays a packet on behalf of other nodes . We highlighted the additional delay due to the tick clock, as well as the relationship between the packet sending interval and connInterval. RTT measurements are consistent with latency ones.Regarding latency, we showed the different performance characteristics when the sender is the actual source of the packets (approximately, between 0 and connInterval and the application data interval, assuming periodic transmission from a sender. The connInterval setting significantly affects the average current consumption, along with the rest of related parameters. However, the impact of the data interval setting on these performance parameters is limited.We modeled the current consumption of the 6LN, for three different BLE hardware platforms. We found significant differences across the considered platforms in terms of current consumption and duration of the different states related to a given action. The models allowed us to determine the device average current consumption, device lifetime, and energy efficiency of communication, as a function of The maximum 6LN device lifetime, assuming a simple 235 mAh battery, is 573 days for a Nordic PCA10028 device, whereas it is 519 days for a LaunchPad device, and 436 days for a SensorTag device. We found that IPv6 header compression provides up to 73 days of additional 6LN device lifetime, on a PCA10028 hardware platform.connInterval decreases.Furthermore, we investigated the feasibility of a 6BLEMesh network comprising battery-operated 6LRs. Despite the greater amount of tasks that 6LRs are involved in, it is possible to achieve battery-operated 6LR lifetimes in the order of several hundreds of days, which may be sufficient for some use cases and scenarios. Battery-operated 6LR lifetime decreases with the number of 6LR neighbors, and it also decreases as


Research is an important undergraduate competence for physicians. However, few studies have assessed the scientific production of medical students in Latin-America. Thus, this study had the objective to assess the rate and characteristics of research publications by undergraduate medical students in 2016, in Lima, Peru.This cross-sectional study included all the students of the eight medical schools in Lima (Peru). The medical students included were collected from the registry of the National Medical Examination (taken during their last year of undergraduate studies) in 2016. To evaluate their research publications, systematic searches were performed in Google Scholar and PubMed during August 2018.We studied data from 1241 medical students  from eight medical schools. 173 (13.9%) students published at least one paper, 102 (8.2%) published at least one original paper, and 30 (2.4%) published at least one original paper in PubMed-Indexed journals. We registered a total of 174 papers authored by medical students, of which 98 (56.3%) were published in Peruvian journals, 128 (73.6%) were published in Spanish, 90 (51.7%) had a medical student as the first author, and 43 (24.7%) had a medical student as the corresponding author. The percentage of students with at least one publication was very heterogeneous across the eight medical schools evaluated .Among medical students in Lima, one out of seven had published at least one paper, one out of 12 had published at least one original paper, and one out of 40 had published at least one original paper in PubMed-Indexed journals. Scientific production was very heterogeneous across medical schools. Social science; Medical students; Medical These cIn recent years, a growing number of studies are assessing the scientific production of medical students in different countries or regions , 18, 19,In Latin-America, few studies have assessed the scientific production of a defined group of medical students, and these studies were performed in only one university , and in Lima is the capital and largest city of Peru, and it has eight medical schools: two receive public funding, and three require a theses dissertation for acquiring a medical degree. Given these heterogeneities across medical schools in Lima, it is relevant to evaluate the scientific production of medical students in each medical school for better understanding of the state of research by medical students. Thus, this study aimed to evaluate the rate and characteristics of research publications by undergraduate medical students in 2016, in Lima, Peru.22.1A cross-sectional study was performed. The study population included graduates from all eight medical schools located in the city of Lima (Peru), who attended their final year in 2016.In Peru, medical students' study for 7 years, thus the study period of the population included went from 2010 to 2016. Persons that finish high school are able to start medical school regardless their age. It is not needed that medical students publish papers for medical licensing.The characteristics of each university are described in http://www.aspefam.org.pe/). This list is published on free access.We obtained the list of all the names of the medical students from medical schools of Lima (Peru) taking the National Examination Board  in 2016, from the website of the Peruvian Association of Faculties of Medicine   of each student, adding the terms [Peru] or [Lima] separately. This strategy was used in previous studies separately, similar to previous studies , 30. SubTwo researchers independently carried out the systematic search and manual review of the publications of each medical student. Later, a third researcher resolved the discordant cases. We considered any paper published in a scientific journal to be a scientific publication . Books, technical reports, theses, posters, or scientific congresses abstracts were excluded.2.3We collected the variables taking into account two different units of analysis: medical students and papers.2.3.1The following variables were collected for each medical student: gender , medical school in which the undergraduate studies were carried out, having published at least one paper in a scientific journal (yes or no), having published at least one original paper in a scientific journal (yes or no), having published at least one original paper in a scientific journal indexed in PubMed (yes or no), and the year of first publication. The paper was considered to be an "original" paper if it had the following sections: introduction, methods, results, and discussion; or the equivalents. All the papers published up to 2016 were registered .2.3.2The following variables were collected for each paper: name and country of the journal in which it was published , language of the paper  year to which the issue of the journal corresponded, type of article , if the paper was indexed in PubMed (yes or no), if the paper had a medical student as first author (yes or no), if the paper had a medical student as the corresponding author (yes or no), article design , and the article topic .2.4Descriptive analysis was carried out using absolute and relative frequencies for the categorical variables. Data analysis was performed using Stata v14.0.2.5The present study was evaluated and approved by the Ethics Committee of the Universidad Científica del Sur (UCSUR) in Lima, Peru. In addition, following data collection, the names of the medical students were replaced by codes protecting the identity of the participants prior to analysis.3We studied 1241 medical students  from 8 medical schools, of which 173 (13.9%) had published at least a paper, 102 (8.2%) had published at least one original paper, and 30 (2.4%) had published at least one original paper in PubMed . The ranAccording to the type of article, letters to the editor tended to diminish over time, clinical reports tended to increase, while original and other types of articles did not present any defined trend .Figure 1The percentage of students that had published at least one paper was higher in the Universidad Peruana de Ciencias Aplicadas (UPC) (63.6%), followed by the Universidad Peruana Cayetano Heredia (UPCH) (21.4%), the Universidad de San Martín de Porres (USMP) (16.8%), the Universidad Nacional Mayor de San Marcos (UNMSM) (15.1%), the Universidad Ricardo Palma (URP) (8.2%), the Universidad Científica del Sur (UCSUR) (2.0%), the Universidad Nacional Federico Villarreal (UNFV) (1.9%) and the Universidad Peruana San Juan Bautista (UPSJB) (0.0%). However, the percentage of students that had published at least one paper in PubMed was higher for the UPC (13.0%), followed by UNMSM (8.9%) and UPCH (2.4%) .Figure 2We registered a total of 174 papers authored by medical students, of which 98 (56.3%) were published in Peruvian journals, 128 (73.6%) were published in Spanish, 53 (30.5%) were published in 2016, 78 (44.8%) were original articles, 58 (33.3%) were letters to the editor, 81 (46.6%) were indexed to PubMed, 90 (51.7%) had a medical student as the first author, 43 (24.7%) had a medical student as the corresponding author, 41 (52.6%) original articles had an analytic design, and 36 (46.1%) presented a public health/epidemiology topic. Any of the articles followed a qualitative methodology .Table 3C4Our study found that, among medical students in Lima, one out of seven had published a paper, one out of 12 had published an original paper, and one out of 40 had published an original paper in PubMed. The students evaluated published 174 articles, of which just over half were published in Peruvian journals, three out of four were published in Spanish, slightly less than half were original papers, more than half were published between 2015 and 2016, and almost half had a medical student as the first author. Regarding medical schools, great heterogeneity was found with respect to the percentage of students who had published papers, with the UPC presenting the highest percentage.4.1In our study, 13.9% of students had published at least one paper, although this percentage was heterogeneous across medical schools (from 0% to 63.6%). Likewise, previous studies in Peruvian medical schools have reported a heterogeneous prevalence of publication of the undergraduate thesis: 2.7% in a private medical school in Lima during the period 2000–2009 , 17.6% iOn the other hand, according to previous studies, the prevalence of medical faculty members having published a paper in a scientific journal in Peru was 56.2% for scientific research professors in 2011 , 24% forThe percentage of students that had published at least one paper in our study (13.9%) was higher than that of another study carried out in 2009 in 190 Colombian medical students from the University of Cali. In this study the prevalence of scientific production of medical students during their career was 3.2% . Our resIn addition, our findings are similar to reports from outside Latin America: a prospective 2-year follow-up cohort conducted at a medical school in Sweden between 2010-2012 found that 15.5% of medical students had published at least one article within two years after completing their research project , and to 4.2Most of the papers found in the present study were published in Peruvian journals, similar to what has previously been described on evaluating the papers from a scientific congress of medical students in Peru, in which all were published in Peruvian journals . Of the Only one out of four articles were published in English, which may be due to the lack of advanced knowledge of English writing among Peruvian medical students . This coPublications of letters to the editor diminished over time. This may be because the students during their first years focus on papers that do not need much methodological knowledge, as letters to the editor. Moreover, the proportion of clinical reports increased over time, which is expected since these papers need clinical knowledge and access to patients. On the other side, original articles and other types of articles did not present a defined trend.Regarding article design, less than a third of studies were descriptive, which suggest that students are either performing their own inference analyses or are collaborating with other researchers that perform such analyses. With respect to the article topic, just under half of the studies were in the public health/epidemiology, and the less common category was clinical studies. This may be due to the greater ease of conducting public health/epidemiology studies, while permissions for clinical studies tend to be harder to get. Almost half of the articles included had a medical student as the first author, agreeing with a review article published in 2013, which evaluated the scientific production of medical students worldwide in Scopus and PubMed and reported that 48.6% of the 356 papers found had a medical student as the first author . However4.3We found that the UPC, UPCH, UNMSM, and the USMP led the percentage of medical students with at least one paper. However, scientific productions seem to depend on different factors per medical school.structural academic intervention, which includes a sequence of research courses aimed to develop competencies in research [The UPC has developed and applied a research . Professresearch  have tworesearch , and theresearch .On the other hand, UPCH students have a scientific promotion environment. The UPCH is the medical school with the highest scientific production in Peru , 43. ManLastly, the UNMSM , USMP 4, and the4.4We found that one out of seven medical students had published a paper, which is of note considering that Peru has a poor scientific production.structural academic intervention performed by the UPC and determine which approaches are the most adequate for their particular contexts.However, this higher publication rate mainly occurs in Lima, since medical schools located in the rest of the country may have a lower scientific production , 37, bei4.5This study has some limitations: 1) Only one cohort of each medical school was evaluated, which does not represent all the students of each medical school; 2) The sample studied was not representative at a national level but rather was made to evidence the current situation of scientific production of medical students in Peru.Nevertheless, this is the first study to analyze the scientific production of students in a representative population of several medical schools in Lima, Peru, thereby providing an overview of student research in our country.4.6Of a total of 1241 students, the prevalence of scientific production was 14.0%. Moreover, one out of 12 students had published an original article, and one out of 40 had published an original article in PubMed. Of the 174 articles found, just over half were published in Peruvian journals, three out of four were published in Spanish and slightly less than half were original articles. We recommend implementing interventions in Peruvian medical schools in order to increase the scientific production of undergraduate medical students.D. Urrunaga-Pastor, C. A. Alarcon-Ruiz: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.P. Mayta-Tristán, A. Taype-Rondan: Conceived and designed the experiments; Analyzed and interpreted the data; Wrote the paper.P. Heredia, O. Huapaya-Huertas, C. J. Toro-Huamanchumo, T. Acevedo-Villar, L. J. Arestegui-Sánchez: Performed the experiments; Contributed reagents, materials, analysis tools or data; Wrote the paper.This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.The authors declare the following conflict of interests: Diego Urrunaga-Pastor has studied at the Universidad de San Martín de Porres, and is a master degree student at Universidad Peruana Cayetano Heredia. Lizbeth J. Arestegui-Sánchez has studied at the Universidad de San Martín de Porres. Christoper A. Alarcon-Ruiz has studied at Universidad Ricardo Palma, and is a master degree student at Universidad Peruana Cayetano Heredia. Paula Heredia has studied at Universidad Ricardo Palma, and is a master degree student at Universidad de San Martín de Porres. Oscar Huapaya-Huertas has studied at the Universidad Científica del Sur and the Universidad Peruana Cayetano Heredia; and has worked for the Universidad Científica del Sur. Carlos J. Toro-Huamanchumo has studied at the Universidad de San Martín de Porres and Universidad Peruana Cayetano Heredia; and has worked for the Universidad de San Martín de Porres, the Universidad Peruana de Ciencias Aplicadas and the Universidad Peruana Cayetano Heredia. Alvaro Taype-Rondan has studied at the Universidad de San Martín de Porres and Universidad Peruana Cayetano Heredia; and has worked for the Universidad de San Martín de Porres, the Universidad Peruana Cayetano Heredia, and the Universidad Científica del Sur. Percy Mayta-Tristán has studied at the Universidad Nacional Mayor de San Marcos; and has worked for the Universidad Peruana de Ciencias Aplicadas, the Universidad Peruana Cayetano Heredia and the Universidad Científica del Sur.No additional information is available for this paper.


Background: Prostate cancer (PrC) is the second-most frequent cancer in men, its incidence is emerging globally and is the fifth leading cause of death worldwide. While diagnosis and prognosis of PrC have been studied well, the associated therapeutic biomarkers have not yet been investigated comprehensively. This systematic review and meta-analysis aim to evaluate the theragnostic effects of microRNA expressions on chemoresistance in prostate cancer and to analyse the utility of miRNAs as clinical theragnostic biomarkers. Methods: A systematic literature search for studies reporting miRNA expressions and their role in chemoresistance in PrC published until 2018 was collected from bibliographic databases. The evaluation of data was performed as per PRISMA guidelines for systematic review and meta-analysis. Meta-analysis was performed using a random-effects model using Comprehensive Meta-Analysis (CMA) software. Heterogeneity between studies was analysed using Cochran’s Q test, I2 and the Tau statistic. Quality assessment of the studies was performed using the Newcastle–Ottawa Scale (NOS) for the methodological assessment of cohort studies. Publication bias was assessed using Egger’s bias indicator test, Orwin and classic fail-safe N test, Begg and Mazumdar rank collection test, and Duval and Tweedie’s trim and fill methods. Findings: Out of 2909 studies retrieved, 79 studies were shortlisted and reviewed. A total of 17 studies met our eligibility criteria, from which 779 PrC patients and 17 chemotherapy drugs were examined, including docetaxel and paclitaxel. The majority of the drug regulatory genes reported were involved in cell survival, angiogenesis and cell proliferation pathways. We studied 42 miRNAs across all studies, out of which two miRNAs were found to be influencing chemosensitivity, while 21 were involved in chemoresistance. However, the remaining 19 miRNAs did not appear to have any theragnostic effects. Besides, the prognostic impact of the miRNAs was evaluated and had a pooled HR value of 1.960 with 95% CI (1.377–2.791). Interpretation: The observation of the current study depicts the significance of miRNA expression as a theragnostic biomarker in medical oncology. This review suggests the involvement of specific miRNAs as predictors of chemoresistance and sensitivity in PrC. Hence, the current systematic review and meta-analysis provide insight on the use of miRNA as PrC biomarkers, which can be harnessed as molecular candidates for therapeutic targeting. Prostate cancer (PrC) is the fourth-most common cancer across genders and in males is the second-most common. Based on the Globocan 2018 statistics, the total number of new cases was 1,276,106 (7.1%) with a death rate of 4.5% . Australia and New Zealand had the highest age-standardized incidence as well as mortality rates with 86.4 and 10.2 per 100,000 people respectively [Some commonly preferred treatment methods for PrC are surgery , chemothA study by Cochrane et al. 2009 shows that miRNAs are involved in chemoresistance in many cancers . The devChemosensitivity is the measure of the susceptibility of a particular drug towards the tumor. A previous investigation of 56 cancers and seven normal tissues revealed that 39 miRNAs were upregulated and six miRNAs were downregulated in PrC . Both doAnother study in PrC samples evidenced that miRNA-101 regulates the enhancer of zeste homologue 2 (EZH2) . There iThe challenge in choosing a therapy for prostate cancer is the inconsistent levels of PSA in the serum, due to which alternative markers are essential for firm establishment of the correct treatment . miRNAs Thus, there is emerging evidence establishing the importance of miRNA expression in the development of drug resistance in PrC . HoweverPubMed and Science Direct were used to identify relevant literature published until December 2018. The search strategy aimed at collecting articles relating to miRNA, chemoresistance and prostate cancer. The search terms used were “miRNA or microRNA” AND “chemoresistance” AND “prostate cancer”. Only studies that were published in English or had official English translations were included in this study. Manual screening of the reference lists of eligible studies was performed to identify additional relevant articles. Full-text articles were scrutinised after initial screening by titles and abstracts. The final selection was based on predefined inclusion and exclusion criteria. The corresponding authors were contacted for collecting pertinent data if it was found missing in the full texts of the articles. Duplicates were removed, and the study was excluded if it fell within the exclusion criteria .All retrieved articles were evaluated by the reviewers  for selection based on the following criteria:Our primary inclusion criteria were the studies analysing the theragnostic effect of miRNA expressions in both prostate cancer patients and cell lines.Studies reporting chemoresistance in PrC.Studies reporting a miRNA profiling platform.Studies on drug regulatory genes or pathways involved in chemoresistance or sensitivity.Studies reporting miRNA expressions analysis using in-vitro assays on chemoresistance.Inclusion criteria were:Studies published in languages other than English.Letters to the editor, case studies, review articles and studies performed only in PrC patients or in vitro.Studies using PrC patients’ information from GenBank datasets.Disagreements between reviewers were resolved by discussion and consultation with the corresponding author and fifth reviewer.First author and year of publicationCountryPatients’ originEthnicityNumber of samplesCell linesResistant cell lines to chemotherapymiRNA(s) involvedmiRNA profiling platformDrug informationMolecular pathways or gene associatedStudies that complied with the selection criteria were used for extracting study data. Data from the included studies were obtained by S.B., M.R.R., and P.S. and cross-checked by R.J. Corresponding authors of selected articles were contacted for further clarifications and The Dutch Cochrane Centre’s Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines  were usePublication bias is an integral part of a systematic review and meta-analysis ,40. The Comprehensive Meta-Analysis (CMA) software 3.0 was used to analyse the pooled hazard ratio (HR) with 95% confidence interval (CI). In case of a lack of between-study heterogeneity, fixed model effects were used, and if not, random model effects were employed ,45,46,47n = 179) and ScienceDirect (n = 2730). After a thorough screening, 2830 articles were removed for being duplicates, irrelevant, reviews, case studies and letters to the editor. Screening based on inclusion criteria was used to narrow down to 79 potentially eligible studies, and further screening based on exclusion criteria resulted in 17 articles. Initial search identified 2909 relevant studies from PubMed (n = 11) followed by USA (n = 4) and one each from Australia and Austria. The two most preferred chemotherapy agents were docetaxel and paclitaxel.We identified 17 studies involving 779 PrC patients eligible for the systematic review. The common in-vitro assay types and related number of studies are represented in A total of 42 miRNAs were studied as observed in the pooled study data of this systematic review. Of these, 34 miRNAs were observed to be downregulated, and six were upregulated. A total of 19 downregulated miRNAs  were correlated with an increase in chemoresistance and two downregulated miRNAs (miR-34a and 212) appeared to be associated with increased chemosensitivity. It was also seen that three upregulated miRNAs  correlated with increased chemoresistance. It was found that 15 downregulated miRNAs  and three upregulated miRNAs  had no effect on chemoresistance or sensitivity. High expression was observed in miRNA-10b, 17, 132, 155, 222, 301b and low expression of miRNA-1, 20a, 20b, 21, 22, 25, 29b, 30d, 31, 34a, 125a-3p, 132, 143, 144, 146a, 181a, 199a, 199a-5p, 200a, 200b, 200c, 203, 204, 205, 212, 222, 375, 429, 495 and 590-5p was observed. Of the 17 chemotherapy drugs studied, docetaxel is the most commonly used. Overall, 21 microRNAs were linked to the development of chemoresistance, and two microRNAs were linked to chemosensitivity.A total of 17 drugs were used as chemotherapy in the pooled studies; docetaxel (332 patients), paclitaxel (77 patients), dihydrotestosterone (DHT) (40 patients), AR inhibitor (MDV3100) (40 patients), cisplatin (40 patients), bicalutamide (30 patients), azacytidine (25 patients), DZNep (8 patients), tyrosine kinase inhibitors (25 patients), cyclopamine (3 patients), AR expression (30 patients), topotecan (25 patients), doxorubicin (25 patients), trichostatin A (7 patients), estramustine (40 patients), androgen-deprivation therapy (25 patients) and thapsigargin (7 patients).The miRNA-mediated chemoresistance pathways are represented in miRNA-34a, 200b, 200c and 205 were studied in two studies each. It was observed that miRNA-34a was downregulated on treatment in two studies  and was found to influence the AMPK/mTOR and Hedgehog signalling pathways thereby inducing chemosensitivity and resistance, respectively. PrC treatment with docetaxel was associated with downregulation of miRNA-200b through activation of the BMI-1 gene, contributing to chemoresistance. In another report, miRNA-200c was found to be downregulated during the treatment of docetaxel, paclitaxel and cyclopamine, which in turn triggered the E-cadherin and Hedgehog pathway leading to chemoresistance. Finally, miRNA-205 downregulation was observed on the treatment of docetaxel and DZNep resulting in chemoresistance mediated through EZH2 and E-cadherin gene .p-value: 0.000) was obtained  and low expression of miR-20a , 21 , 200a , 200b , 200c , 375 , 429  and 590-5p  was observed. Out of 17 articles, only one article reported the HR and 95% CI value. The study that reported the HR values for nine miRNAs was used for this meta-analysis. A pooled HR value of 1.960 with a 95% CI  of 0.05893 or a two-tailed p-value of 0.11785 .In this case, Kendall’s tau b  is 0.41667, with a one-tailed t = 3.53225, df = 7. The one-tailed p-value (recommended) is 0.00478, and the two-tailed p-value is 0.00957.In this case, the intercept (B0) is 18.97814, 95% confidence interval , with This method suggests that three studies are missing . Under tPublication bias analysis of the included studies was conducted to study the effect of publication bias on the results of this study. The drug resistance mechanisms in PrC are being extensively studied, as indicated by the emerging studies ,60,61,62The previous meta-analysis on prostate cancer was carried out deciphering the role of miRNAs targeting the androgen receptor . miRNA-2The contradicting results of miRNA-375 expression in one of our studies show it is downregulated while another study reported upregulation of this miRNA in serum samples, indicating their role in the development of AIPCs . miRNA-3miRNA-10b is a diagnostic marker for glioma , breast EZH2 plays a key role in cancer progression , and itsPC3 and DU145 cell lines are being used for evaluating transcriptional activity , in cancThis systematic review and meta-analysis follow appropriate best practice research and statistical guidelines, and the following points accentuate this approach. Initially, the studies chosen were selected from a global arena, where there is a diversity in the selection of patients and their outcomes; secondly our selection criteria (which follow the PRISMA guidelines) help us to engage and have access to an extensive global literature database. An analysis of the publication bias was minimised to minimise the heterogeneity between the studies selected in our meta-analysis.This comparison will help future researchers to evaluate and publish articles from separate patients, which will collectively add to the knowledge base around miRNA prognosis in PrC patients. From this point of view, this study brings out more value for future researchers and technicians regarding predicting miRNA as a valuable prognostic biomarker. The use of subgroup analysis also took into consideration demographic characteristics and repeated miRNAs to provide a better understanding of the survival outcomes of PrC patients. Additionally, the authors believe that this is the foremost systematic review and meta-analysis study on the prognostic utility of miRNAs in PrC patients.The majority of the included studies in our meta-analysis were on patients from Asian and Caucasian backgrounds, which might limit the applicability of the results. From the prognostic point of view of these specific miRNAs, only one study reported the HR and 95% CI value, which is a major limitation, as the rest of the values were estimated from KM curves. Finally, potential biases and confounders cannot be avoided completely, since all studies included had observational designs. Our hallmarks of the PrC provide an overview of the miRNAs involved in drug resistance. The identified miRNAs can be used as diagnostic, prognostic and therapeutic biomarkers in PrC.It is expected that analysing the graph based on the correlation between pairs of miRNAs using cluster editing will reveal other drug regulatory pathways that are not detected yet. This is because clusters (cliques) of mutually pairwise correlated miRNAs represent a strong indication of potential chemoresistance pathways. In fact, clustering can be used as a verification phase or to possibly disclose other pathways that are not detected yet.There is extensive anticipation regarding the use of miRNAs as a possible predictor of chemoresistance in prostate cancer as the available markers are unreliable. There are a significant number of published studies on the evaluation of miRNA regulation in prostate cancer. Our systematic review and meta-analyses from recent clinical evidence demonstrate that miRNAs facilitate drug resistance and sensitivity in prostate cancer patients. The hallmarks of specific miRNAs in prostate cancer as highlighted by our study might provide insights into the regulation of miRNAs and the genes associated with the process of drug resistance, thereby helping future clinicians and researchers in designing efficient clinical trials and in-vitro studies. We have provided a list of miRNAs and their respective pathway targets for routine therapeutic purposes. Further research is required to highlight which specific miRNAs may be intricately involved in chemoresistance and sensitivity.


PGR, HSD3B2, CYP17A1, CYP11A1, CYP21A2, STS, and CYP19A1, and 12 novel genes: ROCK2, TBP, GTF2H2, GTF2B, DHCR24, DHCR7, FDFT1, LSS, SQLE, MSMO1, CYP51A1, and PANK3. These will be utilized for further research into the function of the HPO axis. This study has highlighted the major role of the HPO axis in the reproduction of hens at the four developmental stages and explored the novel factors that might regulate reproduction, thus providing new insights into the function of the HPO axis on the reproductive system.Ovarian follicular development is an extremely complex and precise process in which the hypothalamic-pituitary-ovarian (HPO) axis plays a crucial role. However, research on the regulatory factors of the HPO axis is sparse. In this study, transcriptomes of the tissues in the entire HPO axis at 15, 20, 30, and 68 w of age were analyzed. In total, 381, 622, and 1090 differentially expressed genes (DEGs) were found among the hypothalamus, pituitary, and ovary, respectively. In particular, the greatest number of DEGs (867) was identified from the comparison of ovary at 30 and 15 w, which might be related to ovarian development and function at high ovulation capacity. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that most of these DEGs in the significantly enriched biological process (BP) terms and pathways were primarily involved in tissue development and the regulation of reproductive hormone biosynthesis and secretion. The latter is highly related to the HPO axis. Therefore, a number of hub candidate genes strongly associated with the HPO axis in each tissue were filtered by analyzing the Protein-protein interaction (PPI) network and seven known reproductive hormone-associated key genes were obtained:  Egg production is an essential trait for laying hens and for breeding in poultry. The growth and development of chicken ovarian follicles has been found to be directly related to the egg-laying performance . Unlike In laying hens, ovarian follicular development is an extremely complex and precise process involving pre-hierarchical follicle recruitment, selection, and dominance, pre-ovulatory follicles, and ovulation . There aIn recent years, the rapid advancement in molecular biotechnology has been utilized to carry out research into the molecular mechanisms. Hence, to explore the novel genes and regulatory mechanisms of the HPO axis during different stages of ovarian development in hens, the transcriptomes of whole HPO tissues  were analyzed by RNA-seq during four stages: initial ovarian development, sexual maturation, the peak and late laying periods. This study will provide new insights into the function of the HPO axis at different developmental stages of the ovary during reproduction.All animal experiments and animal care in this study were performed in accordance with the regulations for the administration of affairs concerning experimental animals . The protocols were approved by the Henan Agricultural University Institutional Animal Care and Use Committee (Permit Number: 19-0068).ad libitum. The procedures of photoperiod and immunity were performed in accordance with the regular farm management. Selected hens were anesthetized by intravenous injection of pentobarbital sodium  in the wing vein. Under deep anesthesia, hens were euthanized via jugular vein bleeding for sample collection. For sample preparation, the tissues of hypothalamus and pituitary were extracted from each individual and the whole tissue of ovary was collected after removing the follicles that were larger than 2 mm in diameter, then all tissues were immediately frozen in liquid nitrogen and stored at −80°C for RNA extraction.A total of 36 healthy Hy-line brown laying hens at 15, 20, 30, and 68 weeks of age were provided by the poultry germplasm resource farm of Henan Agricultural University and were housed in separate cages, in which each age phase consisted of 9 hens. Commercial feed and clean drinking water were supplied Total RNA was isolated from 36 tissues samples  using Trizol RNA extraction reagent , with each sample consisting of a homogenous mixture from three hens to reduce individual variation. The purity, concentration, and integrity of the RNA were measured and checked using the Nano Photometer spectrophotometer , Qubit RNA Assay Kit in Qubit 2.0 Fluorometer , and an RNA Nano 6000 assay kit of the Agilent Bioanalyzer 2100 system , respectively. All cDNA libraries were sequenced using an Illumina Hiseq 2500 platform and 125 bp paired-end reads were generated.Raw data (raw reads) in the fastq format were first processed through in-house Perl scripts. Clean data (clean reads) were screened by removing reads containing adapters, reads containing ploy-N, and low-quality reads from the raw data. At the same time, Q20, Q30, and GC content of the clean data were calculated. All the downstream analyses were based on the clean data of high quality.p < 0.05, | log fold chang | ≥ 1, and an FPKM > 1 in at least one group.FPKMs (Fragments per kilo-base of exon per million fragments mapped) of gene expression levels in each sample were calculated using StringTie (v2.1.1) and the obtained read counts were normalized by TMM . Differep-value < 0.01 was used to indicate the significantly enriched terms. Pathway enrichment analysis was implemented using the KEGG database and KOBAS software programs to test the statistical enrichment of the DEGs , according to the manufacturer’s protocol. Real-time PCR was performed using iTaqTM Universal SYBR Green Supermix Kit  using a Light Cycler 96 instrument  at 95°C for 3 min; 40 cycles of 95°C for 10 s, annealing at 60°C for 30 s, 72°C for 30 s, and 72°C for 1 min. The sequences of all primers are listed in To evaluate the quality of the Illumina sequencing, a total of 3,635,530,764 raw reads were generated from the 36 RNA-Seq datasets. A total of 3,455,715,304 high-quality clean reads were obtained after screening the raw reads and were used for mapping and transcriptome assembly. The average Q20, Q30, GC contents, and error rates were 96.21, 90.86, 49.52, and 0.02%, respectively, which was high enough for further analysis .To investigate the key genes of the HPO axis that were involved in follicular development and ovarian function, the differentially expressed genes (DEGs) of the hypothalamus, pituitary, and ovary at the four stages of development of laying hens were analyzed , 2. AmonHierarchical clustering heatmaps of all the DEGs with different combinations of ages in the three tissues of the HPO axis were produced . The thrp < 0.01). Only the top 20 significant BP terms from the large dataset of each tissue are presented in Upregulated and downregulated DEGs in the six combinations of each tissue were used for GO and KEGG analysis. In the GO enrichment analysis, there were 112 significantly enriched biological process (BP) items in the hypothalamus, and 178 and 709 significant BP terms were obtained in the pituitary and ovary, respectively (p < 0.05). In these significant pathways, both focal adhesion and extracellular matrix (ECM)-receptor interaction were found in all the tissues, which were involved in cell adhesion, migration, proliferation, and differentiation, thereby mediating tissue development  as well as the progesterone receptor (PGR) related to other proteins  involved in the response to hormone stimulus from the hypothalamus and ovary. Furthermore, five hub genes  were observed in the ovary, which are crucial genes for the synthesis of estrogen, androgen, and progesterone. Moreover, pantothenate kinase 3 (PANK3) was found, which is involved in lipid synthesis and cholesterol, and is a necessary precursor of steroid hormone synthesis, which indicates that PANK3 may affect the expression of sex hormones , and then rapidly develops until reaching the largest size with numerous ovarian follicles during the peak period of egg production (28–32 w post hatch). This could explain why the greatest number of DEGs was found in the comparison between the15 and 30 w . MoreoveThe significantly enriched BP terms from the GO analysis in the three tissues of the HPO axis elucidated that most of the DEGs were involved in tissue development and the regulation of hormone secretion. The BP terms of catecholamine uptake, regulation of GTPase activity, regulation of phospholipase activity, neurotransmitter reuptake, and regulation of the phospholipase C-activating G-protein coupled receptor (GPCR) signaling pathway in the hypothalamus are well known to be involved in the release and function of GnRH/GnIH, which indicated that GnRH/GnIH conducted its effects via the related biology process and stimulated/inhibited the secretion of FSH and LH in the pituitary gland and ultimately affecting the reproductive system . In the p < 0.05) , which reflected age-related alterations in tissue development  . Focal aelopment . Furtherelopment . In addiROCK2, TBP, GTF2H2, and GTF2B) were found in the hypothalamus. Some researchers have reported that Rho-Kinase2 (ROCK2) is a key downstream target of the small GTPase Rho family, which participates in various cellular activities, such as myosin phosphorylated, actomyosin contraction, and cell motility (TBP), general transcription factor IIH subunit 2 (GTF2H2), and general transcription factor IIB (GTF2B) as general transcription factors, assemble on the promoters of the gene transcribed by RNA polymerase II, which trigger transcriptional regulation by interacting with gene regulatory factors (TBP interacts with TBP-associated factors (TAFs) to identify and activate gene transcription, of which selective promoter factor 1 (SP-1), as one of the TAFs, could induce GnRH responsiveness to the LHβ promoter by mediating the actions of both adenylate cyclase (AC) and protein kinase C (PKC)  . Moreove pathway . This deDHCR24) has been shown to mediate the protective effect of IGF-1 and estrogen stimulation in the nervous system (NRIP1), a co-regulator of estrogen receptor-α (ERα), directly mediates the expression of PGR and NR5A1 , which are well known to respond to plasma progesterone levels and regulate reproductive development and the secretion of gonadotropin in the pituitary  participated in the biosynthesis of steroid hormones  and Henan Agricultural University Institutional Animal Care and Use Committee (Permit Number: 19-0068).YT and XK acquired the funding for the study. JL and CL performed research, analyzed the data, and wrote the manuscript. QL and GL analyzed the data and was involved in the study design. HL and WL performed the statistical analysis. YT and XK were involved in the design of the study. YT conceived the study and involved in its design and coordination. All the authors read and approved the final manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Lysosomal function has a central role in maintaining neuronal homeostasis, and, accordingly, lysosomal dysfunction has been linked to neurodegeneration and particularly to Parkinson’s disease (PD). Lysosomes are the converging step where the substrates delivered by autophagy and endocytosis are degraded in order to recycle their primary components to rebuild new macromolecules. Genetic studies have revealed the important link between the lysosomal function and PD; several of the autosomal dominant and recessive genes associated with PD as well as several genetic risk factors encode for lysosomal, autophagic, and endosomal proteins. Mutations in these PD-associated genes can cause lysosomal dysfunction, and since α-synuclein degradation is mostly lysosomal-dependent, among other consequences, lysosomal impairment can affect α-synuclein turnover, contributing to increase its intracellular levels and therefore promoting its accumulation and aggregation. Recent studies have also highlighted the bidirectional link between Parkinson’s disease and lysosomal storage diseases (LSD); evidence includes the presence of α-synuclein inclusions in the brain regions of patients with LSD and the identification of several lysosomal genes involved in LSD as genetic risk factors to develop PD. Lysosomes are subcellular acidic vesicles containing acid hydrolases. The main function of these organelles is the degradation of intracellular and extracellular macromolecules that are broken down into their primary constituents to be further recycled in the cytosol with the aim of building new cellular components.The cell relies on lysosomes to properly eliminate and recycle proteins, lipids, polysaccharides, carbohydrates, and other type of molecules to maintain cellular homeostasis. When the lysosome is unable to degrade these macromolecules, the abnormal accumulation of material within lysosomes first causes lysosomal impairment, which can ultimately lead to general cellular dysfunction.To date, approximately seventy lysosomal storage diseases (LSDs) have been described, many of which are caused by loss-of function mutations in lysosomal hydrolases but can also be caused by other lysosomal-related proteins, such as lysosomal transmembrane proteins and members of the trafficking machinery that transport newly synthesized lysosomal proteins to the lysosomes .The mainNeurons, due to their morphology, metabolic features, and postmitotic state, are particularly vulnerable to deregulation of the clearance systems that are needed to provide new components to build macromolecules as well as to eliminating toxic or unwanted components.Lysosomes are the terminal compartment where intracellular macromolecules delivered by autophagy and extracellular macromolecules delivered by endocytosis are finally degraded. The whole system, known as the autophagy–lysosomal–endosomal system, is a complex network of coordinated and connected mechanisms with the lysosome as the terminal point and where the different pathways converge .Lysosomes are loaded with approximately 60 different types of hydrolytic enzymes capable of degrading all types of diverse macromolecules such as proteins, polysaccharides, lipids, carbohydrates, and nucleic acids. Once macromolecules are broken down, their essential components are transported to the cytosol for their reuse or alternatively to be released from the cell through exocytosis. The role of lysosomes in the degradation and recycling of extracellular and intracellular components is a key factor in the maintenance of cellular homeostasis ,4Autophagy, from the Greek “auto” (self) and “phagy” (eating), is the catabolic process by which intracellular components are delivered to lysosomes for degradation. Delivery of cytosolic material to lysosomes in mammalian cells can occur through three different routes that differ in the specificity of the target material to be degraded (cargo), how it is delivered into lysosomes and the mechanisms of regulation ,6.Macroautophagy, usually referred to only as “autophagy”, is responsible for the degradation of most intracellular components as a major mechanism to maintain cellular homeostasis and the proper balance between protein synthesis and degradation. It consists of the sequestration of cargo within double membrane vesicles called autophagosomes that will fuse to lysosomes for degradation of their contents. Macroautophagy is considered a dynamic process that comprises the sequential steps of initiation, elongation of the autophagosome membrane, recognition and trapping of the cargo, transport of the loaded autophagosomes towards the lysosomes, fusion of the autophagosome with lysosome, and, ultimately, degradation of the cargo inside the lysosomes . Macroautophagy substrates can include nonspecific cytosolic content or selective cargo that are recognized and delivered to lysosomes through highly regulated mechanisms. These forms of selective macroautophagy include the degradation of mitochondria (mitophagy) , peroxisBasal macroautophagy is responsible for the continuous turnover of intracellular components, while induced autophagy is a stress-response mechanism activated under different conditions such as starvation, exposure to oxidative stress, hypoxia, or mitochondrial damage. Thus, autophagy can be activated under situations where specific materials such as misfolded or aggregated proteins, damaged organelles, or external pathogens must be eliminated from the cell or when essential basic elements such as amino acids are needed to rebuild new macromolecules. Mammalian target of rapamycin complex I (mTORC1) is the main negative regulator of macroautophagy and induces autophagy in response to amino acid deprivation (starvation), insulin, growth factors, ATP levels, glucose, hypoxia, and other forms of stress .Chaperone-mediated autophagy (CMA) is the second type of autophagy in mammalian cells. In this pathway, substrates are soluble cytosolic proteins containing a specific CMA motif related to the pentapeptide KFERQ . In the Finally, microautophagy is the third type of known autophagy and is a relatively poorly studied mechanism in mammalian cells that involves the sequestration and degradation of complete regions of the cytosol, including proteins and organelles, through the direct invagination of the lysosomal membrane itself .In the central nervous system (CNS), the autophagy pathways are particularly relevant since most of the cells are postmitotic, which requires good quality control systems to eliminate altered proteins and damaged organelles . In factEndocytosis is the process by which the cell internalizes proteins and lipids from the plasma membrane and extracellular material . After iEndocytosis has a special relevance in the brain, given that it is involved in essential functions such as neurotransmitter and neurotrophic signaling ,25. SincParkinson’s disease is the second most common neurodegenerative disorder, after Alzheimer’s disease, and the most common movement disorder. It affects 1% of the population over the age of 60 ,28. The The main neuropathological feature is the death of dopaminergic neurons from the substantia nigra pars compacta (SNpc), which explains the motor symptoms, and the presence of intracytoplasmic protein inclusions called Lewy bodies in the affected areas .SNCA, LRRK2, PRKN (PARK2), PINK1, PARK7 (DJ-1), VPS35, ATP13A2, PLA2G6, and FBXO7 [TMEM230, LRP10, NUS1, and ARSA have recently been postulated as disease-causing candidates in Mendelian PD; however, further studies are needed to confirm their involvement in the development of the disorder [PD can be classified as familial or sporadic according to the presence or absence of a family history of PD. Approximately 15% of the cases are considered familial; however, only approximately 5–10% present a monogenic form of the disorder. Several genes have been associated with both autosomal dominant and recessive forms of PD, including nd FBXO7 ,33. In adisorder .GBA gene, which encodes the lysosomal enzyme β-glucocerebrosidase (GCase), are the major genetic risk factors for PD that have been described [LRRK2, SNCA, and MAPT [LRRK2 and SNCA) have been associated with both Mendelian and sporadic forms of PD, indicating that different disease-related genetic mechanisms may coexist at the same locus [In sporadic cases, the etiology is multifactorial and involves an interplay between environmental and genetic factors. The main risk factor for PD is age ; howeverescribed ,40. Otheand MAPT , and somme locus .Interestingly, an important number of these risk factors and identified causal genes for monogenic forms of PD are involved in the autophagy–lysosomal–endosomal pathways, pointing to the major involvement of these pathways in the pathogenesis of the disorder.α-Synuclein protein is the main component of Lewy bodies found in the affected brain areas of PD patients. Accordingly, PD is considered a synucleinopathy that encompasses neurodegenerative diseases characterized by the progressive accumulation of α-synuclein aggregates in the CNS. In addition to PD, dementia with Lewy bodies (DLB), and multiple system atrophy (MSA) are also synucleinpathies that accumulate cytoplasmic synuclein aggregates in the frontal cortex and inside oligodendrocytes, respectively .SNCA gene, and was the gene where the first autosomal dominant mutations for PD were found [α-Synuclein is a small (14 kDa) soluble protein. In humans, it is encoded by the re found ,44,45. Ire found ,44,45, are found ,47,48. Tre found ,47,48.Alpha-synuclein is found abundantly in physiological conditions. Normal levels of α-synuclein inside the cell are maintained through the balance between synthesis and degradation. Given that the oligomeric state of α-synuclein as a monomeric, oligomeric, fibrillary, or aggregated protein is a process highly dependent on protein concentration, an alteration in any of the mechanisms regulating a-synuclein turnover leads to an increased cytoplasmic concentration of α-synuclein and consequently promotes the formation of oligomeric and fibrillary species . The preSNCA gene [SNCA gene [SNCA gene that constitute risk factors for sPD [Increased expression of α-synuclein caused by multiplications (duplications or triplications) of the NCA gene ,50,51, aNCA gene ,53, incrNCA gene ,54,55,56NCA gene . In addi for sPD .Since altered levels of synuclein can promote PD progression, α-synuclein turnover mechanisms play an important role in PD development, and autophagy pathways have a key role in maintaining proper α-synuclein neuronal levels. Wild-type α-synuclein is mostly degraded through the autophagic pathways—macroautophagy but predominantly CMA ,58,59,60α-Synuclein contains the CMA-motif , which iConsistent with these findings, in vitro and in vivo studies have confirmed the key role of CMA in α-synuclein turnover and intracellular levels ,61,62,64Taken into account the key role of the lysosomal-dependent degradation of α-synuclein and the consequences of its inefficient turnover, we can assume that direct or indirect alteration of the lysosomal function, but also the autophagic or endosomal machinery, can trigger the abnormal accumulation of α-synuclein. In the following sections, we will discuss the contribution of these dysfunctions to the pathogenesis of PD.The capacity for lysosomal processing diminishes progressively with aging , and as GBA confer a high risk of developing PD, and mutations in the ATP13A2 gene, which encodes for a lysosomal ATPase, cause a juvenile-onset familial form of parkinsonism [TMEM175, CTSB, SCARB2, ATP6V0A1, GALC, GUSB, and NEU1 as risk factors for PD [CTSD, SLC17A5, and ASAH1 as new risk factors for PD. However, confirmation of these variants by other studies with larger data sets is required [GBA, ATP13A2, LAMP1, and TMEM175 was reported. Altogether, this evidence points towards a model in which common and rare variants in lysosomal genes may contribute to lysosomal dysfunction influencing PD susceptibility. Other factors that may affect lysosomal function indirectly and may modify the risk to develop PD are noncoding variants, copy-number variants, epigenetic factors, and gene–gene and gene–environment interactions. Although few studies have addressed these factors, there is preclinical evidence that, for instance, gene–environment interactions occur [The relevance of lysosomal dysfunction in the pathogenicity of PD has been supported by evidence coming from genetic studies . For insinsonism . In reces for PD ,38,71,72s for PD . This exrequired . Recentlrequired . An assoBelow we describe some of these lysosomal proteins that have been linked to PD.GBA encodes for the lysosomal enzyme β-glucocerebrosidase (GCase), which hydrolyses glucosylceramide (GlcCer) to ceramide and glucose. Homozygous and heterozygous compound mutations in the GBA gene cause Gaucher’s disease (GD), which is one of the most common LSD. It is characterized by a decrease in GCase activity and the subsequent accumulation of glucosylceramide in several organs. GD patients but also GBA asymptomatic carriers have a five-fold increase in their lifetime risk of developing PD in comparison to the general population [GBA gene are the most common genetic risk factor for PD [pulation . In factr for PD ,40. Simir for PD . Howeverr for PD ,100,101GBA mutations or a reduction in GCase activity through pharmacological or genetic approaches have resulted in the accumulation of α-synuclein in several in vivo and in vitro models, similar to what is observed in PD-GBA brains [The mechanisms by which decreased GCase activity contributes to the pathogenesis of PD are not completely understood; however, a relationship between GCase alterations and α-synuclein pathology has been well established ,103. ThuA brains ,108,109.GBA mutations that cause increased risk of PD produce a reduction in GCase activity. The other hypothesis states that toxicity may occur through a gain-of-function mechanism; misfolded GCase proteins are retained in the ER, overwhelming the folding machinery, and promoting ER stress [GBA [Two main theories have been postulated linking GCase with α-synuclein, namely loss-of-function and toxic gain-of-function of GCase activity . The losR stress  and α-syR stress . It has R stress . Both hyess [GBA ,114,115,GBA mutations, decreased enzymatic activity of GCase was also found, particularly in the SNpc [In patients without the SNpc ,117,118 the SNpc ,120. It the SNpc  detectedthe SNpc . As a fiATP13A2 gene encodes for a lysosomal transmembrane ATPase pump that is involved in cation and polyamine transport, the polyamine-transporting ATPase 13A (ATP13A2) [ATP13A2 has been reported to cause an LSD, a form of juvenile neuronal ceroid lipofuscinosis [The ATP13A2) . MutatioATP13A2) . Moreovescinosis .ATP13A2 gene to early-onset PD [ATP13A2 mutations are a risk factor for PD [In sPD, some studies have linked heterozygous variants in the onset PD ,125,126,onset PD ,128,129.r for PD . Changesr for PD ,130,131,Atp13a2-null mice, others found no changes [Atp13a2-null mice overexpressing human synuclein showed a summatory effect of both genotypes in the progression of sensorimotor deficits, supporting the pathological interaction between both loci [ATP13A2 cause this atypical form of PD through a mechanism dependent on α-synuclein pathology. Defects in mitochondria and clearance of divalent metals secondary to ATP13A2 deficiency may also play a role [ATP13A2 affects the activity of the protein and how this affects the functionality of these processes should also be studied in detail.Patient-derived fibroblasts from patients with Kufor–Rakeb syndrome showed alterations in lysosomal function, including impaired acidification and decreased proteolytic processing causing insufficient substrate degradation and autophagosome clearance ,133. Whi changes ,135. In oth loci . Analysiy a role . How PD TMEM175 gene encodes a transmembrane protein, the endosomal/lysosomal potassium channel TMEM175, which is a K+ channel located in late endosomes and lysosomes. As described previously, this gene has been proposed as a candidate PD susceptibility gene by GWAS and DNA sequencing studies [TMEM175 in a neuroblastoma model resulted in lysosomal and mitochondrial dysfunction, providing functional evidence of the role of this protein in the pathogenesis of PD [The  studies ,37,74. Jis of PD . Interesis of PD .SMPD1 gene encodes the lysosomal enzyme sphingomyelin phosphodiesterase/acid sphingomyelinase (ASMase), which hydrolyzes sphingomyelin into ceramide and phosphocholine. Biallelic mutations in this gene cause the LSD Niemann–Pick diseases types A and B [The  A and B . Loss-of A and B ,140 withSMPD1 carriers present a higher risk of developing PD than the normal population [It has been reported in multiple studies that pulation ,142,143.pulation . FurtherCTSD gene encodes a relevant lysosomal enzyme, cathepsin D, the main aspartic endoprotease responsible for the degradation of long-lived proteins. Biallelic mutations in the CTSD gene cause a severe neurodegenerative LSD known as neuronal ceroid lipofuscinosis 10 (CLN10) [CTSD has been proposed by Robak and colleagues [The  (CLN10) . In addilleagues  as a canlleagues . On the lleagues ,144. Redlleagues . In contlleagues  or even lleagues .It is important to note that cathepsin D is involved in the degradation of monomeric and aggregated α-synuclein ,147. In GLA gene encodes α-galactosidase A. Mutations in this gene cause Fabry disease, an X-linked LSD in which the decrease in α-galactosidase activity leads to accumulation of glycosphingolipids, including globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3), with a main effect in the vascular endothelium. An association between Fabry disorder and PD has been proposed, since some Fabry patients present clinical history of parkinsonism [The insonism . In addiinsonism .Besides, in SN and temporal cortex of sPD patients, α-galactosidase activity was shown to be reduced ,153. IntEvidence of lysosomal dysfunction also comes from the analysis of postmortem brain samples of PD individuals. In the SN, lysosomal depletion and decreased levels of different lysosomal-associated proteins, including LAMP-2A, lysosomal-associated membrane protein 1 (LAMP-1), and heat shock cognate 71 kDa protein (HSC70), have been observed ,145,155.In addition to the implication of lysosomal proteins in PD pathogenesis, a bidirectional link between LDSs and PD has been established. As described above, a higher burden of rare variants in LDS genes has been reported in PD patients . FurtherDespite this evidence, in addition to Gaucher disease, which is one of the most prevalent LSD , few patMost of the lysosomal genes proposed as a genetic risk factors for PD cause a LSD when biallelic mutations are present . MoreoveAs mentioned above, an important link between disruptions in the autophagic pathways (both CMA and macroautophagy) and the pathogenesis of PD has been observed, since alterations in these systems have been observed in familial and sporadic cases of the disease. Interestingly, mutations in some genes involved in the autophagy machinery have been identified as mutations with Mendelian inheritance or risk factors in PD.As previously mentioned, CMA impairment due to the presence of mutant or modified α-synuclein species can play an important role in PD etiology. In addition to α-synuclein genetic and posttranslational modifications, other PD-related proteins have been shown to affect autophagy activity ,63.Leucine-rich repeat serine/threonine-protein kinase 2(LRRK2) is a large protein with multiple protein–protein interaction domains and two enzymatic regions with GTPase and kinase activity. Due to its ability to interact with several proteins, LRRK2 is a dynamic protein capable of forming different complexes and controlling diverse functions at different subcellular locations, cell types, and conditions and accordingly has been implicated in a large number of cellular pathways . TherefoLRKK2 are the most known genetic cause of familial PD, accounting for 5% of total familial cases [LRRK2 mutations have been described, only a few have been proven to cause PD, and p.G2019S is the most abundant. As also observed in other PD-related genes, GWAS analysis has also identified genetic variants at the LRRK2 locus as risk factors for sPD [Mutations in al cases ,170. Alt for sPD ,171.LRRK2 can interfere with macroautophagy activity, although the exact mechanism that explains how LRRK2 regulates the macroautophagy pathway is still not clear and remains controversial [Several studies have shown that mutant oversial .In addition to the role of LRRK2 in macroautophagy, mutant forms of the protein have also been involved in CMA inhibition. LRRK2 is a CMA substrate; however, the p.G2019S LRRK2 mutated protein remains stacked in the CMA receptor on the surface of the lysosomes, avoiding its own degradation and inhibiting the degradation of other CMA substrates, including α-synuclein, which tends to oligomerize into toxic species .Ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1), a ubiquitin hydrolase associated with familial PD, also behaves like mutant α-synuclein and mutant LRRK2; it interacts with the lysosomal membrane receptor LAMP-2A to be digested through the CMA pathway, but in its mutated form it remains stacked in the lysosomal membrane and blocks CMA machinery . AlthougPINK1 and PRKN are two genes linked to familial cases of PD. Their products, PINK1 and E3 ubiquitin–protein ligase Parkin, are involved in mitophagy; the selective recognition and degradation of mitochondria by macroautophagy [utophagy .PINK1 is important as a stress sensor for mitochondria. It is present at low levels on healthy mitochondria, as it is rapidly degraded as soon as it reaches the mitochondria. However, in damaged or depolarized mitochondria, the degradation process of PINK1 is incomplete, and the full-length protein accumulates on the outer mitochondrial membrane (OMM), where it can phosphorylate different proteins, including Parkin and ubiquitin (UB). Parkin is an E3 ubiquitin ligase and requires a phosphorylation mediated by PINK1 for its activation ,177. ActPRKN is the most common autosomal recessive PD-causing gene, especially relevant in juvenile-onset cases [PINK1 causes early-onset autosomal recessive PD and accounts for 1–9% of familial cases. Most of its mutations affect the kinase domain, causing a loss-of-function [In terms of genetics, et cases ,182. It et cases . PINK1 cfunction , but do PINK1 and PRKN genes involved in the initiation of mitophagy can affect the efficiency of this pathway and lead to the inaccurate turnover of mitochondria, accumulation of damaged mitochondria, and ultimately impairment of the bioenergetics of the cell. The presence of mutations in these genes highlights the link between autophagy/mitophagy activity and mitochondrial dysfunction in the pathogenesis of PD [Mutations in is of PD .Additionally, PINK1 and Parkin perform alternative roles in the mitochondrial quality control system of neurons beyond mitophagy and act as stress sensors of different pathways such as immune response. Neuroinflammation has been described to contribute to neuronal degeneration in PD and other neurodegenerative diseases . Both PIFBXO7. Mutations in this gene cause autosomal recessive PD or a parkinsonism disorder, sharing some characteristics with PRKN-associated PD [Drosophila, the mutant Parkin phenotype is rescued by overexpression of wild-type FBXO7 [Another gene related to both PD and mitophagy is iated PD ,189. Theiated PD . FBXO7 aiated PD ,192; thepe FBXO7 .The endocytic system is composed of a series of highly dynamic networks of membrane-enclosed structures and includes different pathways to degrade, recycle, and sort proteins and lipids between the plasma membrane and intracellular compartments. The regulation of the endocytic network is mediated by several protein complexes and by small GTPases, the Rab proteins, and membrane-associated proteins that act as molecular switches to control the identity and relationship of the different types of endosomes . We descVPS35 is a part of the retromer complex involved in endosomal retrograde transport of vesicles to the trans-Golgi network (TGN) and the plasma membrane . FollowiVPS35 gene have connected retromer dysfunction with familial PD, although mutations in VPS35 are rare and account for only approximately 1% of familial parkinsonism [Autosomal dominant mutations in the insonism ,201. Theinsonism .+-ATPase (V-ATPase) for the acidifications of LE and lysosomes [Several other endosomal proteins are involved in PD; DNAJC13, Putative tyrosine-protein phosphatase auxilin (DNAJC6), and the Rab protein GAK15 are involved in the uncoating of clathrin-coated vesicles ,203,204,ysosomes , and SYNysosomes ,209.LRRK2 gene, in addition to its role in autophagy, has also been associated with endocytosis. Among LRRK2 interactions, the protein can bind and phosphorylate proteins involved in the endocytosis machinery, such as VPS35 [LRRK2 can also promote dysfunction of the endosomal system along with the effect of mutant LRRK2 protein in several other cellular processes.Finally, the as VPS35 , VPS52 [as VPS35 , and sevas VPS35 ,212,213.Taken together, these findings point towards a defective endocytic system in several familial and sPD cases that may lead to lysosomal dysfunction and defects in proteostasis ,81.Since the main hallmark of PD is the loss of dopaminergic neurons, most studies have focused on neuronal death. However, in recent years, emerging evidence points out that microglial and astrocytic dysfunction may also play an important role in the pathogenesis of PD.Recently, it has been demonstrated that several genes that have been linked to PD are also expressed in glial cells and in some cases with comparable or even higher levels than neurons ,83. RemaGBA and LRKK2 mutations seem to impair lysosomal degradation of proteins in glial cells, contributing to further accumulation of α-synuclein [PINK1, PRKN, and PARK7 have also been described to alter different glial processes that can impact neuronal survival, including astrocyte proliferation, production of ROS, inflammatory responses, and mitochondrial function [It is known that pathologic α-synuclein is released to neurons and can be internalized and degraded by astrocytes and microglia ,90. Inteynuclein ,93. Thisynuclein ,94. Pertfunction ,97,214.In summary, several PD-linked genes are also expressed in glial cells, and variants in these genes may affect different biological processes essential for CNS homeostasis, contributing to the pathogenesis and progression of PD.In conclusion, multiple type of evidence support the major role of lysosomal dysfunction in the pathogenesis of PD, and also increasing data has linked LSDs with PD. Several genes involved in the lysosomal function, the autophagic pathways, and the endocytic network have been described to be causative in Mendelian forms of PD or have been suggested as a candidate risk of PD genes. A relationship between some of these genes and α-synuclein has been established suggesting that α-synuclein accumulation is secondary to lysosomal dysfunction and may lead to the development of PD. However, the mechanistic association between the pathogenic variants in most of the genes and α-synuclein accumulation remains to be established. The key role of the lysosome in PD has also opened therapeutic opportunities in the treatment of PD; to the well-known pharmacological autophagy inducers tested in the last decade to improve the macroautophagy activity in neurons as a common therapeutic strategy in neurodegenerative diseases , we can