Systemic translocation of S. aureus Drives Anti-CD4 Autoimmunity in Treated HIV Infection

BackgroundIn 2017, our group first demonstrated that autoimmunity contributes to HIV pathogenesis, even without autoimmune disease. This concept is now broadly recognized, exemplified by the role of autoimmunity in severe COVID-19. In people with HIV (PWH) on suppressive ART, anti-CD4 autoantibodies may impair CD4+ T cell recovery, though the mechanisms driving their production remain unclear. Building on evidence from our group and others that Staphylococcus aureus and its peptidoglycan (PGN) promote autoimmunity, we investigated their contribution to anti-CD4 IgG in HIV. MethodsPlasma from 32 ART-naive PWH, 53 ART-treated PWH, and 32 HIV-negative controls was analyzed for IgG autoantibodies and markers of S. aureus translocation using protein array, ELISA, and microarray. EcoHIV mice were injected intraperitoneally with saline, S. aureus PGN, or Bacillus subtilis PGN. PGN structures were compared by mass spectrometry. ResultsAmong 87 autoantibodies, 40% were elevated in ART-naive PWH and largely normalized by ART; however, anti-CD4 IgGs remained elevated in PWH on ART. Anti-CD4 IgG levels inversely correlated with CD4+ T cell counts in ART-treated PWH and positively with S. aureus translocation. In mice, S. aureus PGN induced anti-CD4 IgGs, reduced gut CD4+ T cells, and promoted surface IgG binding and apoptosis in CD4+ T cells. ConclusionS. aureus and its PGN translocation may drive anti-CD4 autoimmunity and hinder immune recovery in PWH on suppressive ART, highlighting S. aureus colonization as a therapeutic target and supporting the development of competitive probiotic interventions such as Bacillus subtilis.