PROJECT SUMMARY: Beyond neutralization, antibodies can elicit an array of Fc-mediated innate immune functions such as antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and antibody-dependent complement deposition (ADCD). These innate immune functions are beneficial, as they contribute to pathogen clearance; however, they also can induce inflammation during viral infections. Antibody glycosylation strongly impacts these functions. For example, fucose reduces ADCC, while sialic acid and galactose are anti-inflammatory and may inhibit ADCP and ADCD. In our R01 AG062383, we asked whether HIV infection during aging is associated with specific IgG glycomic alterations that persist despite long-term antiretroviral therapy (ART). Our data show that antibodies from HIV+ ART+ individuals do indeed exhibit specific glycomic alterations (loss of galactose and fucose) compared to antibodies from HIV-uninfected counterparts in a manner linked to higher inflammation, enhanced ADCC/ADCP/ADCD, and higher incidence of subclinical atherosclerosis. During this analysis, we noticed apparent differences between women and men. During ART+ HIV infection, antibodies from women have a lower level of the anti-inflammatory and anti- ADCP/ADCD sialic acid and galactose and higher levels of the anti-ADCC fucose compared to antibodies from men. Biological sex has increasingly been recognized as an important modulator of immunity and disease progression during HIV infection. However, the mechanisms underlying this phenomenon are unknown but important to understand to design interventions that work for both sexes. These data support our hypothesis that sex-dependent IgG glycomic dysregulation modulates Fc-mediated innate immune functions and inflammation during ART-suppressed HIV infection. We will test this hypothesis with two aims: In Aim 1, we will test the hypothesis that antibodies from women drive higher ADCP/ADCD, higher myeloid inflammation, and lower ADCC than antibodies from men. We expect, based on their glycomic profile, that antibodies from women will drive higher ADCP/ADCD, higher myeloid inflammation, and lower ADCC than antibodies from men. We also expect that these differential abilities will be associated with higher inflammation and inflammation-associated conditions. In Aim 2, we will test the hypothesis that glycoengineered IgGs from women and men can modulate anti-HIV specific Fc-mediated innate immune functions and inflammation. We recently implemented a method to chemo-enzymatically alter the glycosylation of antibodies. We will use this method to alter the glycosylation of antibodies from men and women and test the ability of glycoengineered antibodies to elicit specific innate immune functions and inflammation. We expect that antibodies with profiles similar to those of women (low sialic acid/galactose) will elicit high ADCD/ADCP activities and inflammation. In Summary, this supplement will identify n...