Germinal Center T follicular helper (GC-Tfh) cell impairment in chronic HIV infection involves c-Maf signaling [RNA-seq]

We have recently demonstrated that the function of T follicular helper (Tfh) cells obtained from lymph nodes (LN) of HIV-infected individuals is impaired. We found that these cells were unable to provide proper help to germinal center (GC)-B cells, as observed by altered and inefficient anti-HIV antibody response and premature death of memory B cells. The underlying molecular mechanisms of this dysfunction remain poorly defined. Herein, we have used a unique transcriptional approach to identify these molecular defects. We consequently determined the transcriptional profiles of LN GC-Tfh cells following their interactions with LN GC-B cells from HIV-infected and HIV-uninfected individuals, rather than analyzing resting ex-vivo GC-Tfh cells. We observed that proliferating HIV-infected GC-Tfh cells were transcriptionally different than those from HIV-uninfected individuals, displaying a significant downregulation of immune- and GC-Tfh-associated pathways and genes compared to cells from uninfected individuals. Our results strongly demonstrated that MAF (coding for the transcription factor c-Maf) and its upstream signaling pathway mediators (IL6R and STAT3) were significantly downregulated in HIV-infected subjects, which could contribute to the impaired GC-Tfh and GC-B cell functions reported during infection. We further showed that c-Maf function was associated with the adenosine pathway and that the signaling upstream c-Maf could be partially restored by adenosine deaminase -1 (ADA-1) supplementation. Overall, we identified a novel mechanism that contributes to GC-Tfh impairment during HIV infection. Understanding how GC-Tfh function is altered in HIV is crucial and could provide critical information about the mechanisms leading to the development and maintenance of effective anti-HIV antibodies. Overall design: A total of 5 HIVneg and 7 HIVpos. LNs were collected (6 HIVpos LNs were used in the microarray assay and 3 HIVpos LNs were used in the RNA-seq assay, where 2 of the specimens were common to the 2 assays). Microarrays have not yet been submitted to a public database. SEB coculture: Sorted CFSE-labeled GC-Tfh cells from HIVpos and HIVneg LNs were co-cultured with autologous GC-B cells in the presence of Staphylococcal Enterotoxin B (SEB).