Project Summary/Abstract
Antiretroviral therapy (ART) has improved the lives of people living with HIV (PWH). However, the increased
burden of HIV-associated non-communicable diseases (NCDs) such as diabetes, cardiovascular disease, and
obesity is leading to higher morbidity and mortality among these individuals. The disruption of the intestinal
barrier, resulting in microbial translocation and chronic systemic inflammation, has been linked to NCDs.
However, the mechanism of intestinal barrier disruption in PWH on ART remains incompletely understood.
Interactions between tissue resident CD8+ T cells and the intestinal epithelium are critical for maintaining barrier
integrity. Colonic CD8+ T cells are dependent upon on lipid metabolism for energy production and PPARs
(peroxisome proliferator-activated receptors) are a family of lipid-sensing receptors that critically regulate lipid
metabolism in colon CD8+ T cells. Increases in PPAR-induced lipid metabolism have previously been shown to
boost CD8+ T cell immune function in the tumor microenvironment and improve colitis in patients with
inflammatory bowel disease. In PWH on ART, we show that PPARs are downregulated in colon CD8+ T cells,
which results in impaired internal lipid storage. Moreover, PPAR deficiency in these cells is also associated with
CD8+ T cell-mediated epithelial damage that disrupts intestinal barrier integrity. This has led us to hypothesize
that in PWH on ART, downregulation of PPARs result in impaired lipid metabolism in colonic CD8+ T cells, which
decrease effector functions and leads to impaired intestinal barrier integrity. During the K99 phase, this proposal
aims to determine the effects of PPARs on CD8+ T cell effector function in PWH on ART. In Aim 1 we will use
PPAR knock-out mice to determine the role of PPAR signaling in the CD8+ T cell subpopulations in the mouse
colon (K99 phase). Aim 2 we will characterize the mechanism of how PPAR signaling impacts lipid metabolism
in colonic CD8+ T cells (K99 to R00 transition). In Aim 3, we will determine how dysregulation of cellular
metabolism in colonic CD8+ T cells impacts epithelial function in the intestine (R00 phase). This proposal will
involve using ex vivo intestinal organoids that incorporate colonic CD8+ T cells from human subjects and
genetically engineered mice with deficiencies in CD8+ T cell cellular energy production. To carry out these aims,
the PI has assembled a team with combined expertise in HIV pathogenesis, mucosal immunology,
immunometabolism, intestinal pathology, and single-cell transcriptomics who will collaborate and support the
PI’s work and career development. This proposal seeks to identify novel therapeutic interventions that can
restore tissue-resident CD8+ T cell function in PWH on ART (K99) and characterize the molecular mechanism
of intestinal barrier damage associated with chronic immune activation to help ameliorate NCDs in ART-treated
PWH (R00).