Background
Mycobacterial immune reconstitution inflammatory syndrome (myco-IRIS) and Kaposi sarcoma herpesvirus (KSHV) associated diseases (KAD) remain common in people with advanced HIV in resource-constrained settings. These syndromes can be difficult to differentiate clinically, and optimal treatments remain unknown, highlighting the importance of determining their pathogenesis. We have previously shown greater IFNγ production in myco-IRIS whereas IL18 levels are more prominent in KAD. To expand on these findings, we performed high-dimensional flow cytometry on peripheral blood samples from people with myco-IRIS or KAD to determine key cell subsets and signaling pathways involved in their pathogenesis.
Methods
Samples were obtained from people with HIV (PWH) and active myco-IRIS or KAD (Kaposi sarcoma multicentric Castleman disease, KSHV inflammatory cytokine syndrome). All participants were enrolled in a NIH-IRB approved protocol and were on antiretroviral therapy (ART). A 29-marker flow panel including monocyte and T-cell/NK-cell markers of differentiation, activation, and function was run on all samples at diagnosis. Wilcoxon test, unsupervised clustering, and differential abundance analyses were performed.
Results
Overall, 22-PWH were included (median age 39-years [IQR: 29-46]) with 17-cisgender men (77%). Thirteen-PWH had myco-IRIS (tuberculosis, n=4; nontuberculous, n=9), and 9 had KAD (7 [78%] with concomitant Kaposi sarcoma). Patients with myco-IRIS had a greater percentage of activated (CD38hiHLADR+) CD8 T-cells with greater EOMES+ positivity compared to KAD (p<0.01). Activated CD4 T-cells were similar between the groups, however KAD had greater caspase-1 activation in monocytes (p<0.05) vs myco-IRIS. Unsupervised clustering analysis identified two uniquely expanded activated T-cell populations (Figure-1: CD4s [violet cluster] and CD8s [dark green cluster]) in myco-IRIS compared to KAD with increased cell cycling (Ki-67hi), IL18R+ expression, and mTOR signaling (pS6+) (p<0.01). Patients with KAD had a significant expansion of classical/intermediate monocyte populations (gold clusters) with increased CD163+ and HLADR+ expression as well as greater caspase-1 activation (p<0.01) (Figure-1).
Conclusions
Although clinically indistinguishable, myco-IRIS and KAD demonstrate unique immune profiles with differential activation of signaling pathways within T-cell and monocyte subsets. These different pathways may represent novel treatment targets for future interventional clinical trials.
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