Pattern Recognition Receptor-Initiated Innate Immune Responses In Prostatic Epithelial Cells

Background and objectives:Three major pathogenic states of the prostate,including prostatitis,benign prostatic hyperplasia,and prostate cancer,are related to the local inflammation.However,the mechanisms underlying the initiation of prostate inflammation by microbial infection remain largely unknown.Given that the innate immune responses of the tissue-specific cells to microbial infection contribute to the local inflammation,this study focused on pattern recognition receptor(PRR)-initiated innate immune responses in mouse prostatic epithelial cell(PEC).Materials and methods:Primary PEC and prostatic stromal cell(PSC)were isolated from 8-week-old C57BL/6J mice.The expression of PRR in different prostatic cells were examined and PEC were stimulated with LPS and Flagellin of Gram-negative bacteria,virus RNA analog(poly(I:C)),and herpes simplex virus DNA analog(HSV60)for in vitro study.The mRNA levels were determined by real-time qRT-PCR,and protein levels were examined by Western blot.ELISA was used for detecting the cytokines.Immunocytochemistry and immunofluorescence stainings were used for protein localization.Results:Primary mouse PEC abundantly express various PRRs,including Toll-like receptor 3(TLR3),TLR4,TLR5,melanoma differentiation-associated protein 5(MDA5),and p204.These PRRs can be activated by their respective ligands:LPS and Flagellin for TLR4 and TLR5,poly(I:C)for TLR3 and MDA5,and HSV60 for p204.LPS and Flagellin predominantly induce the expression of inflammatory cytokines and chemokines,including TNF-α,IL-6,MCP-1,and CXCL10.Poly(I:C)and HSV60 predominantly induce the expression of type 1 interferons(IFN-α and IFN-β)and antiviral proteins(MX1,OAS1,and ISG15).Conclusions:PEC constitutively express various PRRs,and these PRRs can be activated by bacterial and viral compoments.Bacterial LPS and Flagellin predominantly induce the expression of pro-inflammatory factors and chemokines,which should be involved in the development of inflammation.Viral nucleic acids induce innate antiviral responses in PEC through the activation of TLR3,MDA5,and p204,thereby inhibiting virus replication.Our results provide insights into mechanisms underlying the inflammatory condition and antiviral responses in the prostate.