A XXXX -like antimicrobial peptide with anti-inflammatory activity from the black @entity238 salivary glands.

@entity1 @entity137 @entity71357 @entity5 @entity39 @entity71936 @entity2822 @entity71937 @entity30958 @entity2823 @entity842 @entity281 @entity3689 @entity238 @entity526 @entity4653
BACKGROUND: Several antimicrobial peptides (AMPs) belonging to the @entity71936 family have been identified from the salivary glands of different black @entity238 species, however, the immunological functions for these molecules were poorly understood. METHODS: A novel @entity71936 -like antimicrobial peptide (SibaCec) was purified using reverse phase high-performance liquid chromatography (RP-HPLC) from the salivary glands of the black @entity238 Simulium bannaense. The @entity3689 sequence of SibaCec was determined by a combination method of automated Edman degradation and cDNA sequencing. The morphologic changes of Gram-negative bacteria @entity526 treated with SibaCec were assessed by @entity4653 ( @entity4653 ). Quantitative PCR (qPCR) was performed to analyze the mRNA expression of the @entity71937 ( @entity71937 ) and pro-inflammatory cytokines. @entity842 (NO) generation was examined using a Griess assay and the secretion of pro-inflammatory cytokines was determined by an enzyme-linked immunosorbent assay (ELISA). The activation of @entity30958 ( @entity30958 ), @entity71357 , and the nuclear translocation of nuclear factor-kappaB (NF-kB) were assessed by Western blotting analysis. Circular dichroism (CD) spectroscopy was performed to evaluate the secondary structure of SibaCec in solvent environment. Interaction of SibaCec with lipopolysaccharide (LPS) was studied using @entity2822 ( @entity2823 )- conjugated LPS aggregates. Neutralization of LPS by SibaCec was assayed with the chromogenic limulus amebocyte lysate (LAL) test. qPCR was also used to analyze the expression of SibaCec mRNA in the salivary glands of insects after @entity281 with the bacteria @entity526 . RESULTS: SibaCec possessed potent antimicrobial activity against Gram-negative bacteria, and showed low @entity137 toward @entity1 cells. @entity4653 analysis indicated that SibaCec killed bacteria through the disruption of cell membrane integrity. Furthermore, SibaCec significantly inhibited lipopolysaccharide (LPS)-induced production of NO and pro-inflammatory cytokines such as @entity5 @entity39 factor-a (TNF-a), interferon-1b (IL-1b) and interferon-6 (IL-6) by blocking the activation of MAPKs and NF-kB signaling pathways. It mainly adopted an a-helix conformation in membrane-mimetic environments. SibaCec could interact and neutralize LPS. @entity281 with bacteria caused an upregulation of the expression of SibaCec. CONCLUSIONS: These results demonstrated that in addition to the bactericidal capacity, SibaCec can function as immune regulator, inhibiting host secretion of inflammatory factors.
