Effects of a Small-Molecule Perforin Inhibitor in a Mouse Model of CD8 T Cell-Mediated Neuroinflammation.

BACKGROUND AND OBJECTIVES Alteration of the blood-brain barrier (BBB) at the interface between blood and CNS parenchyma is prominent in most neuroinflammatory diseases. In several neurologic diseases, including cerebral malaria and Susac syndrome, a CD8 T cell-mediated targeting of endothelial cells of the BBB (BBB-ECs) has been implicated in pathogenesis. METHODS In this study, we used an experimental mouse model to evaluate the ability of a small-molecule perforin inhibitor to prevent neuroinflammation resulting from cytotoxic CD8 T cell-mediated damage of BBB-ECs. RESULTS Using an in vitro coculture system, we first identified perforin as an essential molecule for killing of BBB-ECs by CD8 T cells. We then found that short-term pharmacologic inhibition of perforin commencing after disease onset restored motor function and inhibited the neuropathology. Perforin inhibition resulted in preserved BBB-EC viability, maintenance of the BBB, and reduced CD8 T-cell accumulation in the brain and retina. DISCUSSION Therefore, perforin-dependent cytotoxicity plays a key role in the death of BBB-ECs inflicted by autoreactive CD8 T cells in a preclinical model and potentially represents a therapeutic target for CD8 T cell-mediated neuroinflammatory diseases, such as cerebral malaria and Susac syndrome

Graft-versus-host disease, but not graft-versus-leukemia immunity, is mediated by GM-CSF–licensed myeloid cells

Allogeneic hematopoietic cell transplantation (allo-HCT) not only is an effective treatment for several hematologic malignancies but can also result in potentially life-threatening graft-versus-host disease (GvHD). GvHD is caused by T cells within the allograft attacking nonmalignant host tissues; however, these same T cells mediate the therapeutic graft-versus-leukemia (GvL) response. Thus, there is an urgent need to understand how to mechanistically uncouple GvL from GvHD. Using preclinical models of full and partial MHC-mismatched HCT, we here show that the granulocyte-macrophage colony-stimulating factor (GM-CSF) produced by allogeneic T cells distinguishes between the two processes. GM-CSF drives GvHD pathology by licensing donor-derived phagocytes to produce inflammatory mediators such as interleukin-1β and reactive oxygen species. In contrast, GM-CSF did not affect allogeneic T cells or their capacity to eliminate leukemic cells, retaining undiminished GvL responses. Last, tissue biopsies and peripheral blood mononuclear cells from patients with grade IV GvHD showed an elevation of GM-CSF–producing T cells, suggesting that GM-CSF neutralization has translational potential in allo-HCT

Progressive multifocal leukoencephalopathy genetic risk variants for pharmacovigilance of immunosuppressant therapies

BackgroundProgressive multifocal leukoencephalopathy (PML) is a rare and often lethal brain disorder caused by the common, typically benign polyomavirus 2, also known as JC virus (JCV). In a small percentage of immunosuppressed individuals, JCV is reactivated and infects the brain, causing devastating neurological defects. A wide range of immunosuppressed groups can develop PML, such as patients with: HIV/AIDS, hematological malignancies (e.g., leukemias, lymphomas, and multiple myeloma), autoimmune disorders (e.g., psoriasis, rheumatoid arthritis, and systemic lupus erythematosus), and organ transplants. In some patients, iatrogenic (i.e., drug-induced) PML occurs as a serious adverse event from exposure to immunosuppressant therapies used to treat their disease (e.g., hematological malignancies and multiple sclerosis). While JCV infection and immunosuppression are necessary, they are not sufficient to cause PML.MethodsWe hypothesized that patients may also have a genetic susceptibility from the presence of rare deleterious genetic variants in immune-relevant genes (e.g., those that cause inborn errors of immunity). In our prior genetic study of 184 PML cases, we discovered 19 candidate PML risk variants. In the current study of another 152 cases, we validated 4 of 19 variants in both population controls (gnomAD 3.1) and matched controls (JCV+ multiple sclerosis patients on a PML-linked drug ≥ 2 years).ResultsThe four variants, found in immune system genes with strong biological links, are: C8B, 1-57409459-C-A, rs139498867; LY9 (alias SLAMF3), 1-160769595-AG-A, rs763811636; FCN2, 9-137779251-G-A, rs76267164; STXBP2, 19-7712287-G-C, rs35490401. Carriers of any one of these variants are shown to be at high risk of PML when drug-exposed PML cases are compared to drug-exposed matched controls: P value = 3.50E-06, OR = 8.7 [3.7–20.6]. Measures of clinical validity and utility compare favorably to other genetic risk tests, such as BRCA1 and BRCA2 screening for breast cancer risk and HLA-B*15:02 pharmacogenetic screening for pharmacovigilance of carbamazepine to prevent Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis.ConclusionFor the first time, a PML genetic risk test can be implemented for screening patients taking or considering treatment with a PML-linked drug in order to decrease the incidence of PML and enable safer use of highly effective therapies used to treat their underlying disease

Outbreak of Leishmania braziliensis cutaneous leishmaniasis, Saül, French Guiana [letter]

New World cutaneous leishmaniasis (CL), a zoonotic disease, is increasingly seen among travelers returning from Latin American countries, particularly from Bolivia, Belize, and French Guiana (1). The epidemiology of CL in the Americas is heterogeneous and has complex variations in transmission cycles, reservoir hosts, and sandfly vectors. Changing human activities that affect these factors may have resulted in the emergence of species with distinct pathogenic potentials and responses to therapy. In the Guianan ecoregion complex, leishmaniasis is endemic, and 5 coexisting Leishmania parasite species are known to infect humans: L. guyanensis, L. braziliensis, L. amazonensis, L. naiffi, and L. lainsoni. Among these species, L. guyanensis accounts for ≈85% of CL cases (2). We report an outbreak of 7 cases of L. braziliensis CL that occurred among 24 scientists who participated in a field mission at Limonade Creek in Saül, French Guiana, during October 10–25, 2013. Saül is an isolated village in the Amazonian rainforest (3°55′18′′N, 53°18′02′′W)

PPARγ Controls Dectin-1 Expression Required for Host Antifungal Defense against Candida albicans

We recently showed that IL-13 or peroxisome proliferator activated receptor γ (PPARγ) ligands attenuate Candida albicans colonization of the gastrointestinal tract. Here, using a macrophage-specific Dectin-1 deficient mice model, we demonstrate that Dectin-1 is essential to control fungal gastrointestinal infection by PPARγ ligands. We also show that the phagocytosis of yeast and the release of reactive oxygen intermediates in response to Candida albicans challenge are impaired in macrophages from Dectin-1 deficient mice treated with PPARγ ligands or IL-13. Although the Mannose Receptor is not sufficient to trigger antifungal functions during the alternative activation of macrophages, our data establish the involvement of the Mannose Receptor in the initial recognition of non-opsonized Candida albicans by macrophages. We also demonstrate for the first time that the modulation of Dectin-1 expression by IL-13 involves the PPARγ signaling pathway. These findings are consistent with a crucial role for PPARγ in the alternative activation of macrophages by Th2 cytokines. Altogether these data suggest that PPARγ ligands may be of therapeutic value in esophageal and gastrointestinal candidiasis in patients severely immunocompromised or with metabolic diseases in whom the prevalence of candidiasis is considerable

Neurons are MHC Class I-Dependent Targets for CD8 T Cells upon Neurotropic Viral Infection

Following infection of the central nervous system (CNS), the immune system is faced with the challenge of eliminating the pathogen without causing significant damage to neurons, which have limited capacities of renewal. In particular, it was thought that neurons were protected from direct attack by cytotoxic T lymphocytes (CTL) because they do not express major histocompatibility class I (MHC I) molecules, at least at steady state. To date, most of our current knowledge on the specifics of neuron-CTL interaction is based on studies artificially inducing MHC I expression on neurons, loading them with exogenous peptide and applying CTL clones or lines often differentiated in culture. Thus, much remains to be uncovered regarding the modalities of the interaction between infected neurons and antiviral CD8 T cells in the course of a natural disease. Here, we used the model of neuroinflammation caused by neurotropic Borna disease virus (BDV), in which virus-specific CTL have been demonstrated as the main immune effectors triggering disease. We tested the pathogenic properties of brain-isolated CD8 T cells against pure neuronal cultures infected with BDV. We observed that BDV infection of cortical neurons triggered a significant up regulation of MHC I molecules, rendering them susceptible to recognition by antiviral CTL, freshly isolated from the brains of acutely infected rats. Using real-time imaging, we analyzed the spatio-temporal relationships between neurons and CTL. Brain-isolated CTL exhibited a reduced mobility and established stable contacts with BDV-infected neurons, in an antigen- and MHC-dependent manner. This interaction induced rapid morphological changes of the neurons, without immediate killing or impairment of electrical activity. Early signs of neuronal apoptosis were detected only hours after this initial contact. Thus, our results show that infected neurons can be recognized efficiently by brain-isolated antiviral CD8 T cells and uncover the unusual modalities of CTL-induced neuronal damage

BMJ Med

OBJECTIVE: To evaluate the efficacy of covid-19 convalescent plasma to treat patients admitted to hospital for moderate covid-19 disease with or without underlying immunodeficiency (CORIPLASM trial). DESIGN: Open label, randomised clinical trial. SETTING: CORIMUNO-19 cohort (publicly supported platform of open label, randomised controlled trials of immune modulatory drugs in patients admitted to hospital with moderate or severe covid-19 disease) based on 19 university and general hospitals across France, from 16 April 2020 to 21 April 2021. PARTICIPANTS: 120 adults (n=60 in the covid-19 convalescent plasma group, n=60 in the usual care group) admitted to hospital with a positive SARS-CoV2 test result, duration of symptoms 40. MAIN OUTCOME MEASURES: Primary outcomes were proportion of patients with a WHO Clinical Progression Scale score of ≥6 on the 10 point scale on day 4 (higher values indicate a worse outcome), and survival without assisted ventilation or additional immunomodulatory treatment by day 14. Secondary outcomes were changes in WHO Clinical Progression Scale scores, overall survival, time to discharge, and time to end of dependence on oxygen supply. Predefined subgroups analyses included immunosuppression status, duration of symptoms before randomisation, and use of steroids. RESULTS: 120 patients were recruited and assigned to covid-19 convalescent plasma (n=60) or usual care (n=60), including 22 (covid-19 convalescent plasma) and 27 (usual care) patients who were immunocompromised. 13 (22%) patients who received convalescent plasma had a WHO Clinical Progression Scale score of ≥6 at day 4 versus eight (13%) patients who received usual care (adjusted odds ratio 1.88, 95% credible interval 0.71 to 5.24). By day 14, 19 (31.6%) patients in the convalescent plasma group and 20 (33.3%) patients in the usual care group needed ventilation, additional immunomodulatory treatment, or had died. For cumulative incidence of death, three (5%) patients in the convalescent plasma group and eight (13%) in the usual care group died by day 14 (adjusted hazard ratio 0.40, 95% confidence interval 0.10 to 1.53), and seven (12%) patients in the convalescent plasma group and 12 (20%) in the usual care group by day 28 (adjusted hazard ratio 0.51, 0.20 to 1.32). In a subgroup analysis performed in patients who were immunocompromised, transfusion of covid-19 convalescent plasma was associated with mortality (hazard ratio 0.39, 95% confidence interval 0.14 to 1.10). CONCLUSIONS: In this study, covid-19 convalescent plasma did not improve early outcomes in patients with moderate covid-19 disease. The efficacy of convalescent plasma in patients who are immunocompromised should be investigated further. TRIAL REGISTRATION: ClinicalTrials.gov NCT04345991

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Migration et pathogénicité des lymphocytes T CD8 au sein du système nerveux central

Le système nerveux central (SNC) bénéficie localement d'un statut immunologique privilégié contrôlant activement les réponses immunitaires potentiellement délétères. Une réponse immunitaire peut toutefois s'y développer au cours de maladies infectieuses ou inflammatoires. Le syndrome inflammatoire de restauration immunitaire (SIRI) est une situation particulière dans laquelle les dommages tissulaires peuvent être dus à l'agent infectieux lui-même, à la réponse immunitaire qu'il a engendrée, ou aux deux. Notre premier objectif était de préciser le rôle des lymphocytes T CD8 (LTCD8), acteurs cruciaux de la réponse immunitaire adaptative, au cours des SIRI observés chez des patients infectés par le VIH ayant développé une leucoencéphalopathie multifocale progressive (LEMP). Nous montrons qu'au cours des LEMP-SIRI, les LTCD8 sont bénéfiques au contrôle de l'infection par le virus JC, au prix d'une destruction accrue des oligodendrocytes infectés. Ces résultats illustrent le rôle des LTCD8 dans la clairance d'un agent pathogène infectant le SNC mais aussi dans la genèse de dommages tissulaires collatéraux. Nous avons ensuite développé un modèle murin de SIRI affectant le SNC basé sur le transfert de LTCD8 naïfs réactifs vis-à-vis d'un néo-antigène présent dans le SNC de souris lymphopéniques. Nous montrons que la lymphopénie est nécessaire mais non suffisante au développement de dommages tissulaires du SNC induits par les LTCD8 qui dépendent d'une part de l'inhibition de mécanismes régulateurs, et d'autre part de l'existence au niveau du SNC de signaux de danger. Ces résultats soulignent les conditions nécessaires au développement du SIRI. Ce modèle murin permettra de tester des stratégies thérapeutiques permettant de moduler la restauration immunitaire pathologique dans le SIRI. Le développement de dommages tissulaires du SNC implique la migration des lymphocytes encéphalitogéniques à travers la barrière hémato-encéphalique. Les molécules d'adhésion impliquées dans la migration des LTCD8 vers le SNC sont mal connues. En utilisant un panel d'anticorps monoclonaux bloquants des molécules d'adhésion ou leurs ligands, nous montrons dans un modèle murin d'auto-immunité du SNC que la migration des LTCD8 cytotoxiques est dépendante de l'intégrine a4ß1. Nous suggérons par ailleurs que VCAM-1 n'est vraisemblablement pas l'unique ligand d'a4ß1, et que d'autres molécules pourraient participer à la migration des LTCD8 vers le SNC. L'identification de molécules additionnelles spécifiquement impliquées dans la migration de populations cellulaires encéphalitogéniques pourrait permettre de mieux préserver les mécanismes participant à l'immunosurveillance du SNC. In fine, notre travail contribue à accroitre les connaissances sur les mécanismes de migration et la pathogénicité des LTCD8 au niveau de SNC en s'appuyant sur des observations faites tant sur des modèles animaux d'inflammation neurologique que chez l'Homme.The central nervous system (CNS) is considered as a unique immune-privileged environment allowing a basal immune surveillance under physiological conditions, and restraining potentially deleterious inflammatory reactions in disease states. Nevertheless, an immune response may develop in the CNS during infectious or inflammatory diseases. The inflammatory immune reconstitution syndrome affecting the CNS (neuro-IRIS) is a particular setting in which tissue damage may be due to the infectious agent itself, the immune response it has generated, or both. CD8 T cells are key players of the adaptive immune response involved in the pathogenesis of infectious or inflammatory diseases of the CNS. Our first aim was to clarify the role of CD8 T cells in the pathophysiology of IRIS that occurred in HIV-infected patients developing progressive multifocal leukoencephalopathy (PML), a severe demyelinating disease due to reactivation of the JC polyomavirus. Analysis by histology, immunohistochemistry and confocal microscopy of PML-IRIS lesions shows the dominance of CD8 T cells, among which a cytotoxic subset engaged JC virus infected oligodendrocytes. During PML-IRIS, the CD8 T cell response is beneficial in controlling JC virus infection, at the cost of increased destruction of infected oligodendrocytes. These results illustrate the role of CD8 T cells in the clearance of a neurotropic pathogen, but also in the genesis of collateral tissue damage. We then developed a murine model of neuro-IRIS based on the transfer of naive CD8 T cells reactive to a neo-antigen selectively expressed in oligodendrocytes of lymphopenic mice. We show that lymphopenia is necessary but not sufficient to trigger CD8 T cell-mediated CNS tissue damage. Development of neuro-IRIS also requires the overcoming of regulatory mechanisms, and the presence of CNS danger signals. These findings underscore the conditions necessary for the development of CNS tissue damage in a setting of immune recovery. This mouse model will help to test therapeutic strategies relevant for HIV-infected patients suffering from neuro-IRIS, aiming to modulate the deleterious immune reconstitution, without dampening it. The development of CNS tissue damage implies the migration of encephalitogenic cells across the blood-brain barrier. Little is known about adhesion molecules involved in the migration of CD8 T cells to the CNS. Using a panel of monoclonal antibodies blocking adhesion molecules or their ligands, we show in a murine model of CNS autoimmunity that migration of CD8 T cells is dependent on the integrin a4ß1. We further suggest that VCAM-1 is probably not the only ligand for a4ß1, and that other molecules may be involved. The identification of additional molecules specifically implicated in the migration of encephalitogenic cell populations may raise the potential for selective control of their trafficking into the brain, preserving better preserve the immune surveillance of the CNS. Ultimately, our work based on observations of neurological inflammation in both animal models and Humans helps to increase the knowledge on the mechanisms of migration and pathogenicity of CD8 T cells in the CNS

Impact of previous exposure to systemic corticosteroids on unfavorable outcome in patients hospitalized for COVID-19

International audienceBackground: The impact of prior exposure to systemic corticosteroids on COVID-19 severity in patients hospitalized for a SARS-CoV-2 pneumonia is not known. The present study was designed to answer to this question. Methods: The population study was the Covid-Clinic-Toul cohort which records data about all hospitalized patients with a positive reverse transcriptase polymerase chain reaction for a SARS-CoV-2 infection at Toulouse University hospital, France. Exposure to systemic corticosteroids was assessed at hospital admission. A propensity score (PS) according to corticosteroid exposure was calculated including comorbidities, clinical, radiological and biological variables that impact COVID-19 severity. The primary outcome was composite, including admission to intensive care unit, need of mechanical ventilation and death occurring during the 14 days after hospital admission. Logistic regression models adjusted for the PS (overlap weighting) provided odds ratios (ORs) and their 95% confidence intervals (95% CIs). Results: Overall, 253 patients were included in the study. Median age was 64 years, 140 patients (59.6%) were men and 218 (86.2%) had at least one comorbidity. Seventeen patients (6.7%) were exposed to corticosteroids before hospital admission. Chronic inflammatory disease (n = 8) was the most frequent indication. One hundred and twenty patients (47.4%) met the composite outcome. In the crude model, the OR of previous exposure to systemic corticosteroids was 1.64; 95% CI: 0.60-4.44. In the adjusted model, it was 1.09 (95% CI: 0.65-1.83). Conclusion: Overall, this study provide some evidences for an absence of an increased risk of unfavorable outcome with previous exposure to corticosteroids in the general setting of patients hospitalized for COVID-19