SC-514

Varicellovirus bovinealpha 1 and 5 (formerly bovine alphaherpesvirus type 1 and 5, BoAHV-1 and BoAHV-5) are closely related and can be isolated from similar clinical conditions, including respiratory and nervous diseases, genital infections and abortion. Pathogens' activation of toll-like receptors (TLRs) induces the expression of proinflammatory cytokines and antimicrobial peptides such as cathelicidins. Cathelicidins are presumed to act as endogenous ligands of TLRs, stimulating, in turn, their activation. Cattle's innate immune responses mediated by TLRs and cathelicidins remain undefined. This work aimed to study the interaction mechanisms between TLR7 and a bovine cathelicidin (bovine myeloid antimicrobial peptide (BMAP)28 and their influence on the replication of BoAHV-1 and BoAHV-5. It was shown that in vitro infection by BoAHV-1 and BoAHV-5 induces the innate immune responses associated with TLR7 and BMAP28 in primary cultured bovine fetal lung cells. Pretreatment with TLR7 agonist (imiquimod) or an endogenous cathelicidin inductor (sodium butyrate) enhanced the innate immune response to BoAHV mediated by TLR7 signalling, BMAP28, TNFα, IFNβ and IFNγ. It exerted an antiviral effect, decreasing BoAHV replication. Inhibition of endosomal TLRs and downstream signalling molecules MAPK, NF-κβ, IKK-2, and JNK II counteracted these antiviral effects. Therefore, BMAP28 shows novel roles in modulating the immune response induced by TLR7 activation through signalling pathways involving kinases and NF-κβ. Enhancing TLR7 and endogenous cathelicidin expression could be a complementary tool for the prevention and/or control of BoAHV infections.

Inflammation is a key factor in the pathogenesis of dry eye disease (DED). We aimed to investigate the role of microRNA-146a (miR-146a) in regulating corneal inflammation in a mouse model of benzalkonium chloride (BAC)-induced dry eye and the TNF-α-induced NF-κB signaling pathway in human corneal epithelial cells (HCECs). A mouse model of dry eye was established by administering with BAC to BALB/c mice, and the expression of TNF-α, IL-1β, IL-6, IL-8, cyclooxygenase 2 (COX2), interleukin-1 receptor-associated kinase 1 (IRAK1) and TNF receptor-associated factor 6 (TRAF6) in the corneas of dry eye model mice was significantly increased; this was accompanied by the upregulation of miR-146a and activation of the NF-κB pathway. In vitro, TNF-α induced miR-146a expression in HCECs, while the NF-κB inhibitor SC-514 reduced the expression of miR-146a. Overexpression of miR-146a decreased the expression of IRAK1 and TRAF6, which have been identified as targets of miR-146a. Furthermore, overexpression of miR-146a suppressed NF-κB p65 translocation from the cytoplasm to the nucleus. Moreover, overexpression of miR-146a attenuated the TNF-α-induced expression of IL-6, IL-8, COX2 and intercellular adhesion molecule 1 (ICAM1), while inhibition of miR-146a exerted the opposite effect. Our results suggest that miR-146a mediates the inflammatory response in DED. MiR-146a negatively regulates inflammation in HCECs through the IRAK1/TRAF6/NF-κB pathway, and this may serve as a potential therapeutic approach for the treatment of DED.