Mechanisms of CD4 T-Cell Death among HIV-Infected, HAART-Treated African Adults Displaying Poor CD4 T-Cell Reconstitution Despite Effective Viral Suppression
Parent Project: UCSF-Gladstone Center for AIDS Research (CFAR)
Most HIV-infected subjects exhibit a progressive rise in CD4 T-cell counts after initiation of highly active antiretroviral therapy (HAART). However, a subset of individuals exhibit very poor CD4 T cell recovery despite effective control of viremia. Increased activation-induced programmed cell death of CD4 T cells has been proposed as a mechanism underlying poor immune recovery. We propose to perform a nested case control study utilizing a rural cohort of HIV-infected adults whose CD4 T-cell counts have remained low (<50 cell increase) despite HAART for at least six months. PBMCs from 50 poor responders versus 50 responders matched for age, gender, and therapeutic regimen will be analyzed by flow cytometry for evidence of pyroptosis (caspase 1 activation/annexin V binding), apoptosis (caspase 3/6 activation/annexin V binding), and changes in mitochondrial membrane integrity as well as surface immune activation markers (CD68, CD25, CD38, HLA-DR). Results obtained in the two groups will be compared using STATA 11 Student's t-test and logistic regression will be employed to identify clinical and flow cytometric predictors of poor CD4 T cell reconstitution. In vitro survival of unstimulated and anti-CD3/anti-CD28 stimulated CD4 T cells will be studied in these two patient groups in the presence and absence of caspase 3 or caspase 1 inhibitors. If caspase-1 activation is detected in poor responder subjects, their cells will be tested for inflammasomemediated processing and secretion of IL-1 beta. Further, in vitro cell survival will be tested in the presence and absence of glyburide, an FDA-approved oral sulfonyl urea that inhibits the P2X7 purinergic receptor and blocks pyroptosis. Understanding the cell death pathways operating in HIVinfected subjects that respond poorly to HAART could guide future development of targeted therapies to optimize immune cell recovery.
CFAR Faculty Mentor: Warner C. Greene, MD, PhD