Mumps Virus-induced Testicular Innate Immune Responses And Their Effects On Testicular Functions

Backgrounds and objectives:Mumps virus(MuV)infection usually induces orchitis and may lead to male infertility.However,the pathomechanisms of mumps orchitis are largely unknown.This thesis focuses on pattern recognition receptor(PRR)-initiated innate antiviral responses in the testicular cells and their effects on testicular functionsMaterials and Methods:Leydig cells were isolated from C57/BL6 mice.MuV was amplified and tifred in vero cells.Gene expression at mRNA level was analyzed by real-time qRT-PCR.Proteins were determined by Western blot and immunohistochemistry.The concentration of cytokines and testosterone was measured using ELISA.TLR2-/-and TNF-?-/-mice and siRNA approaches were used to investigate gene function.Results:MuV induced innate immune responses in mouse Leydig cells,which result in the production of pro inflammatory cytokines and chemokines,including tumor necrosis factor alpha(TNF-?),Interleukelin-6(IL-6),monocyte chemotactic protein 1(MCP-1),CXC chemokine ligand-10(CXCL10),and type 1 interferons(IFN-? and IFN-?).The MuV-induced cytokine production by Leydig cells was signifcantly reduced by knockout of Toll-like receptor 2(TLR2)or the knockdown of Retinoic acid-inducible gene I(RIG-I)signaling.Moreover,MuV infection suppressed testosterone synthesis by Leydig cells.Intraperitoneal injection of MuV induced inflammatory response in the testis,which is characterized by expanded vessel,macrophage infiltrations,and up-regulation of pro-inflammatory cytokines and chemokines including TNF-?,MCP-1,CXCL10.Testosterone synthesis was inhibited by MuV infection.Moreover,MuV infection induced male germ cell apoptosis and impaired spermatogenesis.Notably,MuV injection did not evidently induce testicular inflammation and dysfunction in TLR2-1-or TNF-?-/-mice.Conclusions:MuV induced innate immune responses in mouse Leydig cells through TLR2 and RIG-I signaling,which result in the production of proinflammatory cytokines and chemokines.MuV-induced TNF-? production is responsible for testicular inflammation and dysfunction.Data of this thesis provides novel insights into the mechanisms underlying the MuV-induced innate immune responses in the testis and testicular dysfunction in mice.