24(th) Annual Canadian Conference on HIV/AIDS Research/24(e) Congrès Annuel Canadien de Recherche sur le VIH/sida CAHR Committees / Comités de l'ACRV

2015 Canadian Journal of Infectious Diseases and Medical Microbiology  
BACkGROUND: The C-type lectin CD161 is expressed by CD4+ and CD8+ T cells sharing conserved transcriptional and functional signature. CD4+ T cells with type-17 profiles derived from CD161+ precursors and CD161-expressing CD8+ T cells share the same differentiation profile and include the unique anti-bacterial CD161++ mucosal-associated invariant T cells (MAIT) expressing invariant TCR Vα7.2. During HIV infection, circulating cells harbouring the signature of CD161+ cells are impaired in blood
more » ... d mucosal compartments. In the female genital tract (FGT), portal of entry for HIV infection, the pattern of CD161 expression on CD4+ and CD8+ subsets and how HIV infection impacts these compartments remain unknown. Here, we explore these questions by characterizing CD161-expressing cells in the FGT of chronically HIVinfected (n=16), HIV-negative newly practising sex work (n=36) and highly HIV-exposed seronegative (HESN) (n=33) female sex workers (FSW) from Nairobi, Kenya. RESULTS: When compared to blood, CD161+CD4+ T cells were enriched in the FGT of HIV-negatives. CD161+CD8+ T cells were also enriched in the FGT of new FSW but not in HESN. Circulating and cervical CD161-expressing cells harboured a more activated profile with tissue-homing properties (CD69, CCR5 and β7) on both CD4+ and CD8+ subsets. The CD161++ subsets included MAIT. Stimulated CD161++ and CD161+CD8+ cells expressed IL-22 at higher frequency than CD161-cells. Expression of IL-17A and IL-22 was enriched in FGT, but independently of CD161 expression in cervical CD4+ cells. CD161++CD8+ T cells were depleted in HIV-positives compared to new FSW in both blood and cervix, but depletion of CD161+CD8+ subset was only observed in cervix. CONCLUSION: Impairment of the IL-17A/IL-22-enriched CD161+ +CD8+ and CD161+ subsets was observed for the first time in the FGT of HIV-infected FSW. Also, the absence of cervical enrichment of CD161+CD8+ cells in HESN agrees with a protective reduction of cervical inflammation. In contrast to blood, CD161 expression did not efficiently describe type-17 CD4+ T cells in the FGT. The FGT unique environment may importantly impact T cells plasticity promoting Th17 differentiation independently of CD161 expression. BACkGROUND: Interleukin (IL)-7 is an essential non-redundant cytokine for T-cell differentiation, proliferation, survival and function. We previously reported a significant down-regulation of the IL-7 receptor (IL-7R)-alpha-chain (CD127) on CD8 T-cells in HIV+ patients, mediated by soluble HIV Tat protein and IL-7, both of which are elevated during HIV infection. We now characterize the detailed mechanisms by which IL-7 suppresses CD127 transcription and protein expression. METHODS: Primary human CD8 T-cells isolated from healthy volunteers were treated with IL-7 and levels of c-Myb, SOCS1-7 and CIS transcripts and protein were examined by qPCR and Western. The interaction of SOCS proteins with CD127 was examined by co-IP and confocal microscopy. Candidate transcriptional repressors were identified using DNA microarrays, PCR-arrays and knockdowns. Nuclear run-on assays and ChIP were used to measure rates of CD127 transcription. RESULTS: Upon binding IL-7, surface CD127 is rapidly phosphorylated and internalized while activation of the JAK/STAT5 pathway induces production of CIS proteins. CIS binds directly to CD127 and co-localizes with both CD127 and early endosomal marker EEA1. Subsequent proteasomal degradation of CD127 and CIS is dependent on an E3 ligase. IL-7 also suppresses CD127 transcription via JAK/STAT5 signaling which up regulates expression of c-Myb. Using siRNA-mediated knockdowns and ChIP, we identified c-Myb as a repressor of CD127 transcription. CONCLUSIONS: IL-7 is currently being investigated as a potential therapy in HIV+ individuals with poor immunological response to antiretroviral therapy. In order to optimize the use of IL-7 in therapeutic settings, it is crucial to understand how expression of the IL-7 receptor is regulated. We show here that IL-7 suppresses CD127 expression by two mechanisms: transcriptional which is dependent on c-Myb and at the protein level by inducing expression of CIS protein which in turn binds to CD127 in early endosomes and shuttles the receptor complex to the proteasome for degradation. québec, qC HIV-1 infection leads to numerous B-cell abnormalities, including hypergammaglobulinemia, non-specific B-cell activation, non-specific class switching, increased cell turn-over, breakage of tolerance, increased immature/transitional B-cells, B-cell malignancies as well as a loss of capacity to generate and maintain memory, all of which contribute to a global impairment of the immune humoral compartment. Several cytokines and soluble factors, which are increased in sera of HIV-1-infected individuals, have been suggested to directly or indirectly contribute to these B-cell dysfunctions and one of these is the B-cell-activating factor (BAFF). We provide evidence that HIV-1 (X4-and R5-tropic) up-regulates BAFF expression and secretion by human monocytes. Moreover, we show that the virus-mediated production of BAFF by monocytes relies on a type-I interferon (IFN) response by a small percentage of plasmacytoid dendritic cells (pDCs) present in the monocyte cultures. HIV-1-induced type-I IFN by pDCs triggers BAFF production in both classical and intermediate monocytes but not in non-classical monocytes, which nonetheless display a very strong basal BAFF production. We demonstrate also that basal BAFF secretion is higher in monocytes obtained from females compared to those from male donors. This study provides a novel mechanistic explanation for the increased BAFF levels observed during HIV-1 infection and highlights the importance of pDC/monocyte crosstalk to drive BAFF secretion.
pmid:26015799 pmcid:PMC4427862 fatcat:hjukjvydzna4pnrq2uzc2hbooi