Identification of natural killer markers associated with fatal outcome in COVID-19 patients

IntroductionIncreasing evidence has shown that coronavirus disease 19 (COVID-19) severity is driven by a dysregulated immunological response. Previous studies have demonstrated that natural killer (NK) cell dysfunction underpins severe illness in COVID-19 patients, but have lacked an in-depth analysis of NK cell markers as a driver of death in the most critically ill patients.MethodsWe enrolled 50 non-vaccinated hospitalized patients infected with the initial virus or the alpha variant of SARS-CoV-2 with moderate or severe illness, to evaluate phenotypic and functional features of NK cells.ResultsHere, we show that, consistent with previous studies, evolution NK cells from COVID-19 patients are more activated, with the decreased activation of natural cytotoxicity receptors and impaired cytotoxicity and IFN-γ production, in association with disease regardless of the SARS-CoV-2 strain. Fatality was observed in 6 of 17 patients with severe disease; NK cells from all of these patients displayed a peculiar phenotype of an activated memory-like phenotype associated with massive TNF-α production.DiscussionThese data suggest that fatal COVID-19 infection is driven by an uncoordinated inflammatory response in part mediated by a specific subset of activated NK cells

CTL Escape Mediated by Proteasomal Destruction of an HIV-1 Cryptic Epitope

Cytotoxic CD8+ T cells (CTLs) play a critical role in controlling viral infections. HIV-infected individuals develop CTL responses against epitopes derived from viral proteins, but also against cryptic epitopes encoded by viral alternative reading frames (ARF). We studied here the mechanisms of HIV-1 escape from CTLs targeting one such cryptic epitope, Q9VF, encoded by an HIVgag ARF and presented by HLA-B*07. Using PBMCs of HIV-infected patients, we first cloned and sequenced proviral DNA encoding for Q9VF. We identified several polymorphisms with a minority of proviruses encoding at position 5 an aspartic acid (Q9VF/5D) and a majority encoding an asparagine (Q9VF/5N). We compared the prevalence of each variant in PBMCs of HLA-B*07+ and HLA-B*07- patients. Proviruses encoding Q9VF/5D were significantly less represented in HLA-B*07+ than in HLA-B*07- patients, suggesting that Q9FV/5D encoding viruses might be under selective pressure in HLA-B*07+ individuals. We thus analyzed ex vivo CTL responses directed against Q9VF/5D and Q9VF/5N. Around 16% of HLA-B*07+ patients exhibited CTL responses targeting Q9VF epitopes. The frequency and the magnitude of CTL responses induced with Q9VF/5D or Q9VF/5N peptides were almost equal indicating a possible cross-reactivity of the same CTLs on the two peptides. We then dissected the cellular mechanisms involved in the presentation of Q9VF variants. As expected, cells infected with HIV strains encoding for Q9VF/5D were recognized by Q9VF/5D-specific CTLs. In contrast, Q9VF/5N-encoding strains were neither recognized by Q9VF/5N- nor by Q9VF/5D-specific CTLs. Using in vitro proteasomal digestions and MS/MS analysis, we demonstrate that the 5N variation introduces a strong proteasomal cleavage site within the epitope, leading to a dramatic reduction of Q9VF epitope production. Our results strongly suggest that HIV-1 escapes CTL surveillance by introducing mutations leading to HIV ARF-epitope destruction by proteasomes

Etude des réponses immunes spécifiques de l'herpès humain virus-8 (HHV-8)

Nous étudions les réponses cellulaires T spécifiques du virus HHV-8 dans différentes situations cliniques : au cours de la maladie de Kaposi-MK et de la maladie de Castleman multicentrique-MCM, qui sont liées au virus, et chez des porteurs asymptomatiques du virus-PA. Notre premier travail montre qu au cours de la MK classique et liée au VIH (n=29 patients), dans un test ELISpot IFN , il existe un déficit quantitatif de cellules T anti-HHV-8 par rapport à des PA (n=23 patients). Cette étude identifie 8 nouveaux épitopes CD8 et CD4 du virus et suggère un déficit spécifique de l immunité cellulaire anti-HHV-8 dans le sang au cours de la MK. Notre second travail mené chez des patients MCM (n=12) montre que les cellules T anti-HHV-8 ne sont pas déficitaires, mais que leur phénotype est plus différencié par rapport aux PA (n=12). Le pourcentage de cellules effectrices peu différenciées est inversement corrélé à la charge virale HHV-8. Par ailleurs, les cellules CD8 anti-HHV-8 sont polyfonctionelles chez les patients MCM et PA. Ces résultats montrent qu au cours de la MCM, les réponses CD8 anti-HHV-8, bien que quantitativement présentes et polyfonctionnelles dans le sang, semblent inefficaces sur le contrôle de la maladie. Ces travaux nous permettent d élaborer 2 modèles physiopathologiques différents au cours de la MK et de la MCMWe study specific-T cell responses to HHV-8 in different clinical situations: during Kaposi sarcoma (KS) and multicentric Castleman disease (MCD), which are HHV-8 related diseases, and in HHV-8 asymptomatic carriers (AC). Our first work during classic and HIV-related KS (n=29 patients) shows a lack of HHV-8-specific T cells in ELISpot IFN assays when compared to AC (n=23 patients). This study identifies 8 new CD4 and CD8 T cell epitopes on HHV-8. Our second work shows that during MCD (n=12 patients), HHV-8-specific CD8 T cells in ELISpot IFN assays are conserved in peripheral blood when compared to AC (n=12 patients), but their phenotype is more differentiated. Percentages of early differentiated effector HHV-8-specific T cells are inversely correlated to HHV-8 viral loads. Furthermore, HHV-8-specific T cells are polyfunctional in MCM and PA patients. These results suggest that during MCD, HHV-8-specific T cells are quantitatively normal and polyfunctional but seems inefficient on MCD control. These studies permit us to elaborate different physiopathological mechanisms for KS and MCMPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Evaluation du test Quantiféron ® -TB Gold In-Tube comme outil diagnostique de tuberculose maladie chez des adultes hospitalisés en maladies infectieuses

PARIS-BIUP (751062107) / SudocSudocFranceF

Natural Killer Cells in Post-Transplant Lymphoproliferative Disorders

Post-transplant lymphoproliferative disorders (PTLDs) are life-threatening complications arising after solid organ or hematopoietic stem cell transplantations. Although the majority of these lymphoproliferations are of B cell origin, and are frequently associated with primary Epstein–Barr virus (EBV) infection or reactivation in the post-transplant period, rare cases of T cell and natural killer (NK) cell-originated PTLDs have also been described. A general assumption is that PTLDs result from the impairment of anti-viral and anti-tumoral immunosurveillance due to the long-term use of immunosuppressants in transplant recipients. T cell impairment is known to play a critical role in the immune-pathogenesis of post-transplant EBV-linked complications, while the role of NK cells has been less investigated, and is probably different between EBV-positive and EBV-negative PTLDs. As a part of the innate immune response, NK cells are critical for protecting hosts during the early response to virus-induced tumors. The complexity of their function is modulated by a myriad of activating and inhibitory receptors expressed on cell surfaces. This review outlines our current understanding of NK cells in the pathogenesis of PTLD, and discusses their potential implications for current PTLD therapies and novel NK cell-based therapies for the containment of these disorders

Cell-Mediated Immune Responses to COVID-19 Infection

International audienceAn unprecedented outbreak of pneumonia caused by a novel coronavirus (CoV), subsequently termed COVID-19 by the World Health Organization, emerged in Wuhan City (China) in December 2019. Despite rigorous containment and quarantine efforts, the incidence of COVID-19 continues to expand, causing explosive outbreaks in more than 160 countries with waves of morbidity and fatality, leading to significant public health problems. In the past 20 years, two additional epidemics caused by CoVs have occurred: severe acute respiratory syndrome-CoV, which has caused a large-scale epidemic in China and 24 other countries; and respiratory syndrome-CoV of the Middle East in Saudi Arabia, which continues to cause sporadic cases. All of these viruses affect the lower respiratory tract and manifest as pneumonia in humans, but the novel SARS-Cov-2 appears to be more contagious and has spread more rapidly worldwide. This mini-review focuses on the cellular immune response to COVID-19 in human subjects, compared to other clinically relevant coronaviruses to evaluate its role in the control of infection and pathogenesis and accelerate the development of a preventive vaccine or immune therapies

Drastic decrease of the HIV reservoir in a patient treated with nivolumab for lung cancer

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Assessment of an ultra-sensitive IFNγ immunoassay prototype for latent tuberculosis diagnosis

International audienceWorldwide there are about 1.7 billion individuals with latent tuberculosis infection (LTBI) and only 5% to 15% will develop active tuberculosis (TB). It is recommended to treat only those most at risk of developing active TB to avoid problems of drug resistance. LTBI diagnosis involves reviewing the individual's medical history, physical examination, and biological tests. Interferon gamma release assays (IGRA) can yield "undetermi-nate" or "uncertain" results, which makes clinical management decisions difficult. We assessed an ultra-sensitive immunoassay prototype based on single molecule array (SiMoA) technology to evaluate its overall performance, and in particular, its performance for indeterminate and uncertain positive or negative samples, as classified by the results from the current ELISA technique used for IFN␥ quantification. We analyzed samples from hospitalized or consulting patients and healthcare workers from three hospitals in Paris, previously classified as negative (n = 30), positive (n = 35), uncertain negative (n = 25), uncertain positive (n = 31), or indeterminate (n = 30). We observed that with the SiMoA assay 83.3% of the indeterminate samples became interpretable and could be classified as negative, whereas 74% of uncertain positive samples were classified as positive. Most uncertain negative samples (72%) were reclassified as uncertain positive (68%) or positive (4%). The results suggest that the ultra-sensitive SiMoA IFN␥ assay could represent a useful tool for the identification of true positive and negative samples among those giving indeterminate or uncertain results with the TB IGRA assay currently used