Mechanisms By Which Mumps Virus Infects Testicular Cells And Impairs Spermatogenesis

Backgrounds and objectives:Mumps virus(MuV)infection freguently causes orchitis and may lead to male infertility.The mechanisms by which MuV causes orchitis and infertility remain unclear.This study investigates the mechanisms underlying MuV infection of testicular cells and spermatpgenesis.Results provide new clues for the prevention and treatment of mumps orchitis.Materials and methods:Primary testicular cells were isolated from C57BL/6 or knockout(TNF-?-/-,CXCL10-/-,Axl-/-,Mer-/-,Ax1-/-Mer-/-)mice.Viral titer was measured by plaque assay.Gene expression level were examined by real-time quantitaitve RT-PCR.AO/EB staining and flow cytometry were used to detect cell apoptosis.Cytokine level was measured by ELISA.Proteins were examined by Western blot.HE staining was used to analyze the damage of MuV on spermatogenesis.Immunohistochemistry and immunofluorescence staining were uesd to detect protein distribution in the testis.Results:MuV infection of Sertoli cells significantly induced CXCL10 expression through TNF-a production.CXCR3 is expressed in spermatogenic cells.CXCL10 induces spermatogenic cells apoptosis by activating Caspase signaling pathway via CXCR3.In vivo experiments confirmed that the upregulation of CXCL10 was associated with spermatogenic cells apoptosis after MuV infection.The local injection of MuV into the testis faintly impaired spermatogenesis at 2 weeks.The spermatogenic damage was recovered 3 weeks past MuV infection,which may be related to the effective antiviral responses in mice.MuV can infect and replicate in mouse Sertoli and Leydig cells.Infectious efficiences of MuV were significantly lower in infect Ax1-/-Mer-/-Leydig cells than wild-type cells.TAM inhibitors significantly MuV infection in Sertoli cells.Gas6 is a common ligand of TAM receptor.Gas6 promotes MuV infection in Sertoli and Leydig cells.Moreover,MuV replication in Axl-/-Mer-/-Sertoli and Leydig cells was significantly reduced,which were associated with the up-regulation of IFN-? and antiviral proteins.Neutralizing antibodies against IFN-?R inhibited the expression of antiviral protein and facilitated MuV replication in testicular cells.Conclusions:MuV infection induces TNF-? production in Sertoli cells,which upregulates the expression of CXCL10.CXCL10 induced apoptosis of spermatogenic cells via its receptor CXCR3.TAM/Gas6 mediate the entry of MuV into testicular cells.TAM receptors promote the replication of MuV in testicular cells by inhibiting the production of IFN-? and antiviral proteins.The results provide novel insights into the mechanisms underlying MuV entry of testicular cells and impairment of male germ cells.