Early loss of splenic Tfh cells in SIV-infected rhesus macaques

Follicular T helper cells (Tfh), a subset of CD4 T lymphocytes, provide crucial help to B cells in the production of antigen-specific antibodies. Although several studies have analyzed the dynamics of Tfh cells in peripheral blood and lymph nodes (LNs) during Aids, none has yet addressed the impact of SIV infection on the dynamics of Tfh cells in the spleen, the primary organ of B cell activation. We show here a significant decrease in splenic Tfh cells in SIVmac251-infected rhesus macaques (RMs) during the acute phase of infection, which persists thereafter. This profound loss is associated with lack of sustained expression of the Tfh-defining transcription factors, Bcl-6 and c-Maf but with higher expression of the repressors KLF2 and Foxo1. In this context of Tfh abortive differentiation and loss, we found decreased percentages of memory B cell subsets and lower titers of SIV-specific IgG. We further demonstrate a drastic remodeling of the lymphoid architecture of the spleen and LNs, which disrupts the crucial cell-cell interactions necessary to maintain memory B cells and Tfh cells. Finally, our data demonstrated the early infection of Tfh cells. Paradoxically, the frequencies of SIV DNA were higher in splenic Tfh cells of RMs progressing more slowly suggesting sanctuaries for SIV in the spleen. Our findings provide important information regarding the impact of HIV/SIV infection on Tfh cells, and provide new clues for future vaccine strategies.This work was supported by CHIR (Canada) and ANRS grants (France). JE thanks the Canada Research Chair program for financial assistance. VR was supported by a doctoral fellowship from FCT (Fundacao para a Ciencia e Tecnologia); code SFRH/BD/64064/2009. We would like to thank the Nonhuman Primate Reagent Resource for kindly providing CXCR5 antibodies. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

CD4 T Follicular Helper Cells and HIV Infection: Friends or Enemies?

Follicular T helper (Tfh) cells, a subset of CD4 T lymphocytes, are essential for memory B cell activation, survival, and differentiation and assist B cells in the production of antigen-specific antibodies. Work performed in recent years pointed out the importance of Tfh cells in the context of HIV and SIV infections. The importance of tissue distribution of Tfh is also an important point since their frequency differs between peripheral blood and lymph nodes compared to the spleen, the primary organ for B cell activation, and differentiation. Our recent observations indicated an early and profound loss of splenic Tfh cells. The role of transcriptional activator and repressor factors that control Tfh differentiation is also discussed in the context of HIV/SIV infection. Because Tfh cells are important for B cell differentiation and antibody production, accelerating the Tfh responses early during HIV/SIV infection could be promising as novel immunotherapeutic approach or alternative vaccine strategies. However, because Tfh cells are infected during the HIV/SIV infection and represent a reservoir, this may interfere with HIV vaccine strategy. Thus, Tfh represent the good and bad guys during HIV infection.JE from the Agence Nationale de Recherches sur le Sida et les Hépatites Virales (ANRS) and from The Canadian HIV Cure Enterprise Team Grant HIG-13305 from the Canadian Institutes of Health Research (CIHR) in partnership with CANFAR and IAS. FM is supported by a fellowship from Fondation du CHU de Québec. CB and YF are supported by fellowships from ANRS. JE acknowledges the support of the Canada Research Chair program. RS is supported by FCT—Fundaçao para a Ciência e a Tecnologia/MEC—Ministério da Educaçao e Ciência através de fundos nacionais e quando aplicavel cofinanciado pelo FEDER, no âmbito do Acordo de Parceria PT2020 referente à unidade de investigaçao n°4293. RS is supported by the Fundaçao para a Ciência e a Tecnologia (FCT) (IF/00021/2014)info:eu-repo/semantics/publishedVersio

Études de la dynamique des cellules Tfh et T CD4 mémoires au cours de l'infection au VIH

Depuis sa découverte, le virus de l’immunodéficience humaine de type 1 (VIH-1) a causé la mort de 33 millions de personnes, et 36,7 millions sont actuellement infectées. Malgré l’existence des thérapies antirétrovirales, celles-ci ne conduisent pas à d’éradiquer le virus. En outre, il n’existe pas de vaccin. Les lymphocytes B, dont la fonction est de produire les anticorps sont dysfonctionnels au cours du VIH-1. Or la majorité des stratégies vaccinales se basent sur la production d’anticorps dépendante des cellules T CD4. Ainsi, la première partie de mon doctorat a été consacré à la compréhension de l’impact du VIH-1 sur les cellules T CD4 folliculaires auxiliaires (Tfh) essentielles à l’activation des lymphocytes B et à la production d’anticorps spécifiques, dans la rate l’organe majeur de la réponse des lymphocytes B. Dans la deuxième partie, j’ai analysé les cellules T CD4 mémoires, Tfh et les lymphocytes B dans les ganglions mésentériques: un site inducteur de la réponse immunitaire intestinale, qui alimente la lamina propria (site effecteur) de la muqueuse intestinale en cellules mémoires. Étant donné l’impossibilité d’étudier ces organes profonds en particulier en phase aiguë chez l’homme, j’ai utilisé le modèle du macaque rhésus infecté par le virus de l’immunodéficience simienne (VIS). Les résultats de ces études montrent que l’évolution vers le SIDA est associée à une déplétion précoce des cellules Tfh et T CD4 mémoires dans la rate et les ganglions mésentériques. Concomitant à cela, je rapporte une déplétion des lymphocytes B mémoires dans la rate et un faible titre d’IgG anti-VIS dans le sérum. En plus, les cellules Tfh commutent leur phénotype d'effecteur mémoire vers celui de centrale mémoire associé à l’expriment de CD127 (récepteur de l’IL-7) et de T-bet (marqueur de cellules Th1). De plus, je montre que la déstructuration des organes lymphoïdes secondaires, ainsi que les cytokines environnementales comme l’IL-7 ou l’IL-27 peuvent contribuer au dysfonctionnement des cellules Tfh puisque ces dernières induisant les facteurs de transcription inhibiteurs des cellules Tfh tels que T-bet, Foxo1, Stat5 et KLF2. En conclusion, mes résultats permettent de mieux comprendre que le dysfonctionnement des lymphocytes B et l’immunodéficience dans la muqueuse intestinale sont associés à la déplétion soudaine des lymphocytes T CD4 mémoires et Tfh dans la rate et les ganglions mésentériques. Par conséquent, prévenir la perte de ces cellules pourrait être une approche thérapeutique et vaccinale prometteuse pour la neutralisation du virus et pour une meilleure immunité intestinale, afin d’empêcher la translocation bactérienne.Since its discovery, HIV-1 has caused the death of 35 million people, and 36.9 million are living infected. Although researches have led to the development of antiretroviral therapies, which not only improve life expectation but also life quality of infected individuals, these therapies are not capable of eradicating the virus, and unfortunately there is no vaccine. The pathogenesis of HIV-1 is linked to a dysfunction of CD4 T cells that favors progression to AIDS. Therefore, given that most vaccines are based on T cell-dependent antibody production, the first part of my PhD research is devoted to understanding the impact of HIV-1 on CD4 T Follicular helper (Tfh) cells, which are essential for B cell activation and the production of specific antibodies. These cells are particularly crucial in the spleen, which is the major organ for B cell response. In the second part, I have analyzed the dynamics of memory CD4 T, Tfh and of B cells in mesenteric lymph nodes: an inductive site of the immune response that provides memory cells to the lamina propria (effector site) of the intestinal mucosa. Given the difficulties to study these deep organs, particularly during the acute phase in humans, I have used rhesus macaques infected with the simian immunodeficiency virus (SIV) to study the dynamics of Tfh cells. My results show an early depletion of splenic Tfh cells during the acute phase; a depletion that persists during the chronic phase within macaques in which the infection rapidly progresses to AIDS. Concomitantly, we report a depletion of memory B cells and low titers of anti-SIV IgG titers in these macaques. Furthermore, I observed a massive depletion of memory CD4 T, Tfh and B cells in mesenteric lymph nodes, as well as a phenotypic change of Tfh cells that become central memory cells associated with the upregulation of the expression of CD127 (IL-7 receptor). My results also show that environmental cytokines such as IL-7 and IL-27 contribute to their dysfunction as support the expression of transcription factors that inhibit Tfh cells such as T-bet, Foxo1 and Stat5. In conclusion, my results provide a better understanding of B cell dysfunction related to the early loss of the Tfh cells during HIV/SIV infection. Moreover, I hypothesize that the loss of immunity in the intestinal mucosa is due to the sudden depletion of memory CD4 T, Tfh and B cells in the mesenteric lymph nodes. Therefore, maintaining Tfh and memory CD4 T cells during the early phase of infection could be a promising therapeutic and vaccine approach for neutralizing HIV/SIV, as well as preventing bacterial translocation

Maturation and mip-1β production of cytomegalovirus-specific T cell responses in Tanzanian children, adolescents and adults : impact by HIV and Mycobacterium tuberculosis co-infections

It is well accepted that aging and HIV infection are associated with quantitative and functional changes of CMV-specific T cell responses. We studied here the expression of Mip-1β and the T cell maturation marker CD27 within CMVpp65-specific CD4+ and CD8+ T cells in relation to age, HIV and active Tuberculosis (TB) co-infection in a cohort of Tanzanian volunteers (≤16 years of age, n = 108 and ≥18 years, n = 79). Independent of HIV co-infection, IFNγ+ CMVpp65-specific CD4+ T cell frequencies increased with age. In adults, HIV co-infection further increased the frequencies of these cells. A high capacity for Mip-1β production together with a CD27low phenotype was characteristic for these cells in children and adults. Interestingly, in addition to HIV co-infection active TB disease was linked to further down regulation of CD27 and increased capacity of Mip-1β production in CMVpp65-specific CD4+ T cells. These phenotypic and functional changes of CMVpp65-specific CD4 T cells observed during HIV infection and active TB could be associated with increased CMV reactivation rates

Correction: Early Loss of Splenic Tfh Cells in SIV-Infected Rhesus Macaques.

[This corrects the article DOI: 10.1371/journal.ppat.1005287.]

Mucosal T follicular helper cells in SIV-infected rhesus macaques: contributing role of IL-27

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Distribution of Tfh cells in the spleen of rhesus macaque infected with SIV.

<p>Splenic tissue sections were stained with antibodies against CXCR5 (blue), CD4 (green) and PD-1 (red) and imaged by confocal microscopy. Representative pictures of the same animals as depicted in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005287#ppat.1005287.g008" target="_blank">Fig 8</a> are shown. Higher magnification is shown on the right part of the picture. Scale bar is shown.</p

Early infection of Tfh cells.

<p>(A) Frequencies of SIV DNA and (B) RNA in sorted Tfh and effector memory CD4 T cells isolated from LNs and spleen of RMs infected with SIV. Each dot represents an individual RM. Statistical analyses are performed using Mann Whitney test. *, p<0.05; **, p<0.01. At day>180, open circles represent fast progressor RMs, PB023 and PB028; and full diamonds represent slow progressor RMs, PB013 and PB044. (C) Correlation between the frequencies of SIV DNA⁺ Tfh cells and the percentage of B cell subsets (as defined in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005287#ppat.1005287.g005" target="_blank">Fig 5</a>) in LNs and spleen of RMs. Each dot represents an individual macaque. Spearman analysis was used for correlations.</p

Genotypes of rhesus macaques included in our cohort.

<p>The table indicates the date of sacrifice, CD4 T cell loss (compared to the baseline), and viral load of uninfected (SIV-) and RMs infected with SIVmac251. Animals were genotyped for MHC class I <i>Mamu-A</i> and <i>Mamu-B</i> haplotypes.</p