CD4 + T cell–dependent and –independent cytokine-chemokine network changes in the immune responses of HIV-infected individuals

A vital defect in the immune systems of HIV-infected individuals is the loss of CD4+ T cells, resulting in impaired immune responses. We hypothesized that there were CD4 + T cell–dependent and –independent alterations in the immune responses of HIV-1 + individuals. To test this, we analyzed the secretion of cytokines and chemokines from stimulated peripheral blood mononuclear cell (PBMC) populations from HIV+ donors, healthy donors, and healthy donors with CD4+ T cells experimentally depleted. Multivariate analyses of 16 cytokines and chemokines at 6 and 72 hours after three stimuli (antibody-coated beads to stimulate T cells and R848 or LPS to stimulate innate immune cells) enabled integrative analysis of secreted profiles. Two major effects in HIV+ PBMCs were not reproduced upon depleting CD4+ T cell in healthy PBMCs: (i) HIV+ PBMCs maintained T cell–associated secreted profiles after T cell stimulation; (ii) HIV+ PBMCs showed impaired IFN- γ secretion early after innate stimulation. These changes arose from hyperactive T cells and debilitated natural killer (NK) cell, respectively. Modeling and experiments showed that early IFN- γ secretion predicted later differences in secreted profiles in vitro. This effect was recapitulated in healthy PBMCs by blocking the interferon- γ ) receptor. Thus, we identified a critical deficiency in NK cell responses of HIV-infected individuals, independent of CD4+ T cell depletion, which directs secreted profiles. Our findings illustrate a broad approach for identifying key disease-associated nodes in a multicellular, multivariate signaling network. chemokine multivariate cytokine decision HIV-related deficiencies in NK cells. Much of field has on alterations in cell how HLA and KIR genetics the susceptibility of NK cells infection as well as disease progression 18, 19, 38 ). Fewer studies have examined the TLR responses of NK cells. NK cells from HIV+ individuals are refractory to TLR7/8 stimulation as determined by measurement of the increased cell-surface abundance of CD69, a marker of activation ( 39 ). Our data expand upon these results by showing functional deficiencies in NK cell responses to both TLR4 and TLR7/8 ligands in HIV+ ARV-treated donors. A previous study showed that NK cells are directly activated by LPS to produce IFN- γ ( 40 ); however, accessory cell–derived IL-12 is required for IFN- γ production by NK cells in response to R848 ( 41 ). Given these divergent mechanisms of NK cell stimulation by innate immune stimuli, we speculate that a major downstream innate signaling node is deficient in NK cells from HIV+ donors, that this node may be sensitized by CD4+ T cells, and that it is largely responsible for the early secretion of IFN- γ . These results echo the communication between NK cells and CD4+ T cells described by Waggoner et al . ( 42 ). Furthermore, our findings complement existing knowledge by emphasizing the critical effect of NK cell deficiencies on the impaired innate immune response of HIV-infected individuals, even in the context of CD4+ T cell depletion and many other HIV-associated immune cell alterations that have been previously reported. Finally, our results implicate early IFN- γ as a critical node in network operation in response innate IFN- γ our analyses its hierarchical nodal