Correct stimulation of CD28H arms NK cells against tumor cells.

Tumor evasion has recently been associated with a novel member of the B7 family, HERV-H LTR-associating 2 (HHLA2), which is mostly overexpressed in PDL-1neg tumors. HHLA2 can either induce a costimulation signal when bound to CD28H or inhibit it by binding to KIR3DL3 on T- and NK cells. Given the broad distribution of CD28H expression on NK cells and its role, we compared two monoclonal antibodies targeting this novel NK-cell engager in this study. We show that targeting CD28H at a specific epitope not only strongly activates Ca2+ flux but also results in NK-cell activation. CD28H-activated NK cells further display increased cytotoxic activity against hematopoietic cell lines and bypass HHLA2 and HLA-E inhibitory signals. Additionally, scRNA-seq analysis of clear cell renal cancer cells revealed that HHLA2+ clear cell renal cancer cell tumors were infiltrated with CD28H+ NK cells, which could be targeted by finely chosen anti-CD28H Abs.

First-in-Human Study in Healthy Subjects with the Noncytotoxic Monoclonal Antibody OSE-127, a Strict Antagonist of IL-7Rα.

OSE-127 is a humanized mAb targeting the IL-7Rα-chain (CD127), under development for inflammatory and autoimmune disease treatment. It is a strict antagonist of the IL-7R pathway, is not internalized by target cells, and is noncytotoxic. In this work, a first-in-human, phase I, randomized, double-blind, placebo-controlled, single-center study was carried out to determine the safety, pharmacokinetics, pharmacodynamics, and immunogenicity of OSE-127 administration. Sixty-three healthy subjects were randomly assigned to nine groups: six single ascending dose groups with i.v. administration (0.002-10 mg/kg), a single s.c. treatment group (1 mg/kg), and two double i.v. injection groups (6 or 10 mg/kg). Subjects were followed during <146 d. OSE-127's pharmacokinetic half-life after a single dose increased from 4.6 (1 mg/kg) to 11.7 d (10 mg/kg) and, after a second dose, from 12.5 (6 mg/kg) to 16.25 d (10 mg/kg). Receptor occupancy was ≥95% at doses ≥0.02 mg/kg, and this saturation level was maintained >100 d after two i.v. infusions at 10 mg/kg. IL-7 consumption was inhibited by OSE-127 administration, as demonstrated by a decreased IL-7 pathway gene signature in peripheral blood cells and by ex vivo T lymphocyte restimulation experiments. OSE-127 was well tolerated, with no evidence of cytokine-release syndrome and no significant alteration of blood lymphocyte counts or subset populations. Altogether, the observed lack of significant lymphopenia or serious adverse events, concomitant with the dose-dependent inhibition of IL-7 consumption by target cells, highlights that OSE-127 may show clinical activity in IL-7R pathway-involved diseases.

Iron and Vitamin B12 Deficiency in Patients with Autoimmune Gastritis and Helicobacter pylori Gastritis: Results from a Prospective Multicenter Study.

INTRODUCTION: Iron and vitamin B12 deficiencies are common in patients with atrophic gastritis, but there are limited data on the prevalence of these deficiencies in different types of atrophic gastritis. METHODS: This multicenter, prospective study assessed micronutrient concentrations in histologically confirmed autoimmune gastritis (AIG, n = 45), Helicobacter pylori-related non-autoimmune gastritis (NAIG, n = 109), and control patients (n = 201). A multivariate analysis was performed to determine factors influencing those deficiencies. RESULTS: The median vitamin B12 concentration was significantly lower in AIG (367.5 pg/mL, Q1, Q3: 235.5, 524.5) than in NAIG (445.0 pg/mL, Q1, Q3: 355.0, 565.0, p = 0.001) and control patients (391.0 pg/mL, Q1, Q3: 323.5, 488.7, p = 0.001). Vitamin B12 deficiency was found in 13.3%, 1.5%, and 2.8% of AIG, NAIG, and control patients, respectively. Similarly, the median ferritin concentration was significantly lower in AIG (39.5 ng/mL, Q1, Q3: 15.4, 98.3 ng/mL) than in NAIG (80.5 ng/mL, Q1, Q3: 43.6, 133.9, p = 0.04) and control patients (66.5 ng/mL, Q1, Q3: 33.4, 119.8, p = 0.007). Iron deficiency and iron deficiency adjusted to CRP were present in 28.9% and 33.3% of AIG, 12.8% and 16.5% of NAIG, and 12.9% and 18.4% of controls, respectively. Multivariate analysis demonstrated that AIG patients had a higher risk of developing vitamin B12 deficiency (OR: 11.52 [2.85-57.64, p = 0.001]) and iron deficiency (OR: 2.92 [1.32-6.30, p = 0.007]) compared to control patients. Factors like age, sex, and H. pylori status did not affect the occurrence of vitamin B12 or iron deficiency. CONCLUSION: Iron and vitamin B12 deficiencies are more commonly observed in patients with AIG than in those with NAIG or control patients. Therefore, it is essential to screen for both iron and vitamin B12 deficiencies in AIG patients and include the treatment of micronutrient deficiencies in the management of atrophic gastritis patients.

A Phase I/IIa study of autologous tolerogenic dendritic cells immunotherapy in kidney transplant recipients.

Kidney transplant survival is shortened by chronic rejection and side effects of standard immunosuppressive drugs. Cell-based immunotherapy with tolerogenic dendritic cells has long been recognized as a promising approach to reduce general immunosuppression. Published trials report the safety and the absence of therapy-related adverse reactions in patients treated with tolerogenic dendritic cells suffering from several inflammatory diseases. Here, we present the first phase I clinical trial results using human autologous tolerogenic dendritic cells (ATDC) in kidney transplantation. Eight patients received ATDC the day before transplantation in conjunction with standard steroids, mycophenolate mofetil and tacrolimus immunosuppression with an option to taper mycophenolate mofetil. ATDC preparations were manufactured in a Good Manufacturing Practice-compliant facility and fulfilled cell count, viability, purity and identity criteria for release. A control group of nine patients received the same standard immunosuppression, except basiliximab induction replaced ATDC therapy and mycophenolate tapering was not allowed. During the three-year follow-up, no deaths occurred and there was 100% graft survival. No significant increase of adverse events was associated with ATDC infusion. Episodes of rejection were observed in two patients from the ATDC group and one patient from the control group. However, all rejections were successfully treated by glucocorticoids. Mycophenolate was successfully reduced/stopped in five patients from the ATDC group, allowing tacrolimus monotherapy for two of them. Regarding immune monitoring, reduced CD8 T cell activation markers and increased Foxp3 expression were observed in the ATDC group. Thus, our results demonstrate ATDC administration safety in kidney-transplant recipients.

Non-permissive human conventional CD1c+ dendritic cells enable trans-infection of human primary renal tubular epithelial cells and protect BK polyomavirus from neutralization.

The BK polyomavirus (BKPyV) is a ubiquitous human virus that persists in the renourinary epithelium. Immunosuppression can lead to BKPyV reactivation in the first year post-transplantation in kidney transplant recipients (KTRs) and hematopoietic stem cell transplant recipients. In KTRs, persistent DNAemia has been correlated to the occurrence of polyomavirus-associated nephropathy (PVAN) that can lead to graft loss if not properly controlled. Based on recent observations that conventional dendritic cells (cDCs) specifically infiltrate PVAN lesions, we hypothesized that those cells could play a role in BKPyV infection. We first demonstrated that monocyte-derived dendritic cells (MDDCs), an in vitro model for mDCs, captured BKPyV particles through an unconventional GRAF-1 endocytic pathway. Neither BKPyV particles nor BKPyV-infected cells were shown to activate MDDCs. Endocytosed virions were efficiently transmitted to permissive cells and protected from the antibody-mediated neutralization. Finally, we demonstrated that freshly isolated CD1c+ mDCs from the blood and kidney parenchyma behaved similarly to MDDCs thus extending our results to cells of clinical relevance. This study sheds light on a potential unprecedented CD1c+ mDC involvement in the BKPyV infection as a promoter of viral spreading.

Dendritic Cells Require TMEM176A/B Ion Channels for Optimal MHC Class II Antigen Presentation to Naive CD4+ T Cells.

Intracellular ion fluxes emerge as critical actors of immunoregulation but still remain poorly explored. In this study, we investigated the role of the redundant cation channels TMEM176A and TMEM176B (TMEM176A/B) in retinoic acid-related orphan receptor γt+ cells and conventional dendritic cells (DCs) using germline and conditional double knockout mice. Although Tmem176a/b appeared surprisingly dispensable for the protective function of Th17 and group 3 innate lymphoid cells in the intestinal mucosa, we found that they were required in conventional DCs for optimal Ag processing and presentation to CD4+ T cells. Using a real-time imaging method, we show that TMEM176A/B accumulate in dynamic post-Golgi vesicles preferentially linked to the late endolysosomal system and strongly colocalize with HLA-DM. Taken together, our results suggest that TMEM176A/B ion channels play a direct role in the MHC class II compartment of DCs for the fine regulation of Ag presentation and naive CD4+ T cell priming.

Monocyte Signature Associated with Herpes Simplex Virus Reactivation and Neurological Recovery after Brain Injury.

Rationale: Brain injury induces systemic immunosuppression, increasing the risk of viral reactivations and altering neurological recovery. Objectives: To determine if systemic immune alterations and lung replication of herpesviridae are associated and can help predict outcomes after brain injury. Methods: We collected peripheral blood mononuclear cells in patients with severe brain injury requiring invasive mechanical ventilation. We systematically searched for respiratory herpes simplex virus (HSV) replications in tracheal aspirates. We also performed chromatin immunoprecipitation sequencing, RNA-sequencing, and in vitro functional assays of monocytes and CD4 T cells collected on Day 1 to characterize the immune response to severe acute brain injury. The primary outcome was the Glasgow Outcome Scale Extended at 6 months. Measurements and Main Results: In 344 patients with severe brain injury, lung HSV reactivations were observed in 39% of the 232 patients seropositive for HSV and independently associated with poor neurological recovery at 6 months (hazard ratio, 1.90; 95% confidence interval, 1.08-3.57). Weighted gene coexpression network analyses of the transcriptomic response of monocytes to brain injury defined a module of 721 genes, including PD-L1 and CD80, enriched for the binding DNA motif of the transcriptional factor Zeb2 and whose ontogenic analyses revealed decreased IFN-γ-mediated and antiviral response signaling pathways. This monocyte signature was preserved in a validation cohort and predicted the neurological outcome at 6 months with good accuracy (area under the curve, 0.786; 95% confidence interval, 0.593-0.978). Conclusions: A specific monocyte signature is associated with HSV reactivation and predicts poor recovery after brain injury. The alterations of the immune control of herpesviridae replication are understudied and represent a novel therapeutic target.

Circulating Regulatory T Cells Expressing Tumor Necrosis Factor Receptor Type 2 Contribute to Sepsis-Induced Immunosuppression in Patients During Septic Shock.

BACKGROUND: Septic shock remains a major cause of death that can be complicated by long-term impairment in immune function. Among regulatory T (Treg) cells, the tumor necrosis factor receptor 2 positive (TNFR2pos) Treg-cell subset endorses significant immunosuppressive functions in human tumors and a sepsis mouse model but has not been investigated during septic shock in humans. METHODS: We prospectively enrolled patients with septic shock hospitalized in intensive care units (ICU). We performed immunophenotyping and functional tests of CD4+ T cells, Treg cells, and TNFR2pos Treg cells on blood samples collected 1, 4, and 7 days after admission to ICU. RESULTS: We investigated 10 patients with septic shock compared to 10 healthy controls. Although the proportions of circulating Treg cells and TNFR2pos Treg-cell subsets were not increased, their CTLA4 expression and suppressive functions in vitro were increased at 4 days of septic shock. Peripheral blood mononuclear cells from healthy donors cultured with serum from septic shock patients had increased CTLA4 expression in TNFR2pos Treg cells compared to TNFR2neg Treg cells. CONCLUSIONS: In patients with septic shock, CTLA4 expression and suppressive function were increased in circulating TNFR2pos Treg cells. We identify TNFR2pos Treg cells as a potential attractive target for therapeutic intervention.

Pharmacokinetics and Safety of XAV-19, a Swine Glyco-humanized Polyclonal Anti-SARS-CoV-2 Antibody, for COVID-19-Related Moderate Pneumonia: a Randomized, Double-Blind, Placebo-Controlled, Phase IIa Study.

We assessed the pharmacokinetics and safety of XAV-19, a swine glyco-humanized polyclonal antibody against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in coronavirus disease 2019 (COVID-19)-related moderate pneumonia. The objective was to evaluate the optimal dose and safety of XAV-19 during this first administration to patients with COVID-19-related moderate pneumonia. In this phase IIa trial, adults with COVID-19-related moderate pneumonia with a duration of ≤10 days were randomized to receive an infusion of XAV-19 at 0.5 mg/kg of body weight at day 1 and day 5 (group 1), 2 mg/kg at day 1 and day 5 (group 2), or 2 mg/kg at day 1 (group 3) or placebo. Eighteen patients (n = 7 for group 1, n = 1 for group 2, n = 5 for group 3, and n = 5 for placebo) were enrolled. Baseline characteristics were similar across groups; median XAV-19 serum concentrations (ranges) at the time of the maximum serum concentration of the drug (Cmax) and at day 8 were 9.1 (5.2 to 18.1) and 6.4 (2.8 to 11.9) µg/ml, 71.5 and 47.2 µg/ml, and 50.4 (29.1 to 55.0) and 20.3 (12.0 to 22.7) µg/ml for groups 1, 2, and 3, respectively (P = 0.012). The median terminal half-life (range) was estimated at 11.4 (5.5 to 13.9) days for 2 mg/kg of XAV-19 at day 1. Serum XAV-19 concentrations were above the target concentration of 10 µg/ml (2-fold the in vitro 100% inhibitory concentration [IC100]) from the end of perfusion to more than 8 days for XAV-19 at 2 mg/kg at day 1. No hypersensitivity or infusion-related reactions were reported during treatment, and there were no discontinuations for adverse events and no serious adverse events related to the study drug. A single intravenous dose of 2 mg/kg of XAV-19 demonstrated high serum concentrations, predictive of potent durable neutralizing activity with good tolerability. (This study has been registered at ClinicalTrials.gov under identifier NCT04453384.).

Regulatory cell therapy in kidney transplantation (The ONE Study): a harmonised design and analysis of seven non-randomised, single-arm, phase 1/2A trials.

BACKGROUND: Use of cell-based medicinal products (CBMPs) represents a state-of-the-art approach for reducing general immunosuppression in organ transplantation. We tested multiple regulatory CBMPs in kidney transplant trials to establish the safety of regulatory CBMPs when combined with reduced immunosuppressive treatment. METHODS: The ONE Study consisted of seven investigator-led, single-arm trials done internationally at eight hospitals in France, Germany, Italy, the UK, and the USA (60 week follow-up). Included patients were living-donor kidney transplant recipients aged 18 years and older. The reference group trial (RGT) was a standard-of-care group given basiliximab, tapered steroids, mycophenolate mofetil, and tacrolimus. Six non-randomised phase 1/2A cell therapy group (CTG) trials were pooled and analysed, in which patients received one of six CBMPs containing regulatory T cells, dendritic cells, or macrophages; patient selection and immunosuppression mirrored the RGT, except basiliximab induction was substituted with CBMPs and mycophenolate mofetil tapering was allowed. None of the trials were randomised and none of the individuals involved were masked. The primary endpoint was biopsy-confirmed acute rejection (BCAR) within 60 weeks after transplantation; adverse event coding was centralised. The RTG and CTG trials are registered with ClinicalTrials.gov, NCT01656135, NCT02252055, NCT02085629, NCT02244801, NCT02371434, NCT02129881, and NCT02091232. FINDINGS: The seven trials took place between Dec 11, 2012, and Nov 14, 2018. Of 782 patients assessed for eligibility, 130 (17%) patients were enrolled and 104 were treated and included in the analysis. The 66 patients who were treated in the RGT were 73% male and had a median age of 47 years. The 38 patients who were treated across six CTG trials were 71% male and had a median age of 45 years. Standard-of-care immunosuppression in the recipients in the RGT resulted in a 12% BCAR rate (expected range 3·2-18·0). The overall BCAR rate for the six parallel CTG trials was 16%. 15 (40%) patients given CBMPs were successfully weaned from mycophenolate mofetil and maintained on tacrolimus monotherapy. Combined adverse event data and BCAR episodes from all six CTG trials revealed no safety concerns when compared with the RGT. Fewer episodes of infections were registered in CTG trials versus the RGT. INTERPRETATION: Regulatory cell therapy is achievable and safe in living-donor kidney transplant recipients, and is associated with fewer infectious complications, but similar rejection rates in the first year. Therefore, immune cell therapy is a potentially useful therapeutic approach in recipients of kidney transplant to minimise the burden of general immunosuppression. FUNDING: The 7th EU Framework Programme.

Breakdown of Immune Tolerance in AIRE-Deficient Rats Induces a Severe Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy-like Autoimmune Disease.

Autoimmune regulator (AIRE) deficiency in humans induces a life-threatening generalized autoimmune disease called autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), and no curative treatments are available. Several models of AIRE-deficient mice have been generated, and although they have been useful in understanding the role of AIRE in central tolerance, they do not reproduce accurately the APECED symptoms, and thus there is still a need for an animal model displaying APECED-like disease. We assessed, in this study, the potential of the rat as an accurate model for APECED. In this study, we demonstrate that in rat, AIRE is expressed by MHC class II (MCH-II)+ and MHC-II- medullary thymic epithelial cells in thymus and by CD4int conventional dendritic cells in periphery. To our knowledge, we generated the first AIRE-deficient rat model using zinc-finger nucleases and demonstrated that they display several of the key symptoms of APECED disease, including alopecia, skin depigmentation, and nail dystrophy, independently of the genetic background. We observed severe autoimmune lesions in a large spectrum of organs, in particular in the pancreas, and identified several autoantibodies in organs and cytokines such as type I IFNs and IL-17 at levels similar to APECED. Finally, we demonstrated a biased Ab response to IgG1, IgM, and IgA isotypes. Altogether, our data demonstrate that AIRE-deficient rat is a relevant APECED animal model, opening new opportunity to test curative therapeutic treatments.

Limited Presence of IL-22 Binding Protein, a Natural IL-22 Inhibitor, Strengthens Psoriatic Skin Inflammation.

Psoriasis is a chronic inflammatory disease resulting from dysregulated immune activation associated with a large local secretion of cytokines. Among them, IL-22 largely contributes to epithelial remodeling and inflammation through inhibiting the terminal differentiation of keratinocytes and inducing antimicrobial peptides and selected chemokines. The activity of IL-22 is regulated by IL-22 binding protein (IL-22BP); however, the expression and role of IL-22BP in psoriatic skin has remained unknown so far. Here we showed that nonaffected skin of psoriasis patients displayed lower expression of IL-22BP than skin of healthy controls. Furthermore, the strong IL-22 increase in lesional psoriatic skin was accompanied by a moderate induction of IL-22BP. To investigate the role of IL-22BP in controlling IL-22 during skin inflammation, we used imiquimod-induced skin disease in rodents and showed that rats with genetic IL-22BP deficiency (Il22ra2-/-) displayed exacerbated disease that associated with enhanced expression of IL-22-inducible antimicrobial peptides. We further recapitulated these findings in mice injected with an anti-IL-22BP neutralizing Ab. Hypothesizing that the IL-22/IL-22BP expression ratio reflects the level of bioactive IL-22 in psoriasis skin, we found positive correlations with the expression of IL-22-inducible molecules (IL-20, IL-24, IL-36γ, CXCL1, and BD2) in keratinocytes. Finally, we observed that serum IL-22/IL-22BP protein ratio strongly correlated with psoriasis severity. In conclusion, we propose that although IL-22BP can control deleterious actions of IL-22 in the skin, its limited production prevents a sufficient neutralization of IL-22 and contributes to the development and maintenance of epidermal alterations in psoriasis.

First-in-Human Study in Healthy Subjects with FR104, a Pegylated Monoclonal Antibody Fragment Antagonist of CD28.

FR104 is a monovalent pegylated Fab' Ab, antagonist of CD28, under development for treatment of transplant rejection and autoimmune diseases. In contrast to CD80/86 antagonists (CTLA4-Ig), FR104 selectively blunts CD28 costimulation while sparing CTLA-4 and PD-L1 coinhibitory signals. In the present work, FR104 has been evaluated in a first-in-human study to evaluate the safety, pharmacokinetics, pharmacodynamics, and potency of i.v. administrations in healthy subjects. Sixty-four subjects were randomly assigned to four single ascending dose groups, two double dose groups and four single ascending dose groups challenged with keyhole limpet hemocyanin. Subjects were followed up over a maximum of 113 d. Overall, the pharmacokinetics of FR104 after a single and double infusions was approximately linear at doses ≥0.200 mg/kg. CD28 receptor occupancy by FR104 was saturated at the first sampling time point (0.5 h) at doses above 0.02 mg/kg and returned to 50% in a dose-dependent manner, by day 15 (0.020 mg/kg) to 85 (1.500 mg/kg). FR104 was well tolerated, with no evidence of cytokine-release syndrome and no impact on blood lymphocyte subsets. Inhibition of anti-keyhole limpet hemocyanin Ab response was dose-dependent in FR104 recipients and was already apparent at a dose of 0.02 mg/kg. Abs to FR104 were detected in 22/46 (48%) of FR104 recipients and only 1/46 (2.2%) was detected during drug exposure. In conclusion, selective blockade of CD28 with FR104 was safe and well tolerated at the doses tested. The observed immunosuppressive activity indicated that FR104 has potential to show clinical activity in the treatment of immune-mediated diseases.

Functional Langerinhigh-Expressing Langerhans-like Cells Can Arise from CD14highCD16- Human Blood Monocytes in Serum-Free Condition.

Langerhans cells (LCs) are epithelial APCs that sense danger signals and in turn trigger specific immune responses. In steady-state, they participate in the maintenance of peripheral tolerance to self-antigens whereas under inflammation LCs efficiently trigger immune responses in secondary lymphoid organs. It has been demonstrated in mice that LC-deprived epithelia are rapidly replenished by short half-life langerin-expressing monocyte-derived LCs (MDLCs). These surrogate LCs are thought to be progressively replaced by langerin(high) LCs arising from self-renewing epithelial precursors of hematopoietic origin. How LCs arise from blood monocytes is not fully understood. Hence, we sought to characterize key factors that induce differentiation of langerin(high)-expressing monocyte-derived Langerhans-like cells. We identified GM-CSF and TGF-ß1 as key cytokines to generate langerin(high)-expressing cells but only in serum-free conditions. These cells were shown to express the LC-specific TROP-2 and Axl surface markers and contained Birbeck granules. Surprisingly, E-cadherin was not spontaneously expressed by these cells but required a direct contact with keratinocytes to be stably induced. MDLCs induced stronger allogeneic T cell proliferations but released low amounts of inflammatory cytokines upon TLR stimulation compared with donor-paired monocyte-derived dendritic cells. Immature langerin(high) MDLCs were responsive to MIP-3ß/CCL20 and CTAC/CCL27 chemokine stimulations. Finally, we demonstrated that those cells behaved as bona fide LCs when inserted in a three-dimensional rebuilt epithelium by becoming activated upon TLR or UV light stimulations. Collectively, these results prompt us to propose these langerin(high) MDLCs as a relevant model to address LC biology-related questions.

Standardized whole blood stimulation improves immunomonitoring of induced immune responses in multi-center study.

Functional immune responses are increasingly important for clinical studies, providing in depth biomarker information to assess immunotherapy or vaccination. Incorporating functional immune assays into routine clinical practice has remained limited due to challenges in standardizing sample preparation. We recently described the use of a whole blood syringe-based system, TruCulture®, which permits point-of-care standardized immune stimulation. Here, we report on a multi-center clinical study in seven FOCIS Centers of Excellence to directly compare TruCulture to conventional PBMC methods. Whole blood and PBMCs from healthy donors were exposed to LPS, anti-CD3 anti-CD28 antibodies, or media alone. 55 protein analytes were analyzed centrally by Luminex multi-analyte profiling in a CLIA-certified laboratory. TruCulture responses showed greater reproducibility and improved the statistical power for monitoring differential immune response activation. The use of TruCulture addresses a major unmet need through a robust and flexible method for immunomonitoring that can be reproducibly applied in multi-center clinical studies. ONE SENTENCE SUMMARY: A multi-center study revealed greater reproducibility from whole blood stimulation systems as compared to PBMC stimulation for studying induced immune responses.

Persistent deficiency of circulating mucosal-associated invariant T (MAIT) cells in ANCA-associated vasculitis.

OBJECTIVE: Mucosal associated invariant T cells (MAIT) and innate lymphoid cells (ILCs) have immunoregulatory functions at mucosal sites and have been involved in various inflammatory and autoimmune diseases. The aim of this study was to assess their frequencies in blood in ANCA-associated vasculitis (AAV). METHODS: The frequencies and function of MAIT cells, ILCs, γδT, iNKT, NK cells were analyzed by flow cytometry on PBMC of patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) without any treatment, in acute (AP) and remission phase (RP) and compared with healthy controls (HC). RESULTS: The frequencies of MAIT cells were strongly decreased in GPA and MPA in AP compared to HC, both in never treated and in relapsing patients and independently of patient age. This was associated with an activated phenotype of patient MAIT cells, as shown by increased expression of CD69 and IFNγ. MAIT cells remained decreased during RP in AAV patients. The frequencies of iNKT and γδT cells were unaffected compared to HC, whereas those of NK cells were slightly reduced during AP in MPA. We also observed a significant decrease in frequencies of total ILCs with decreased ILC2 and ILC3 and increased ILC1 during AP in both GPA and MPA compared to HC. These frequencies normalized during RP. Interestingly, we observed a significant correlation between the frequency of total ILCs and BVAS. CONCLUSION: We show for the first time that AAV are associated with a major decrease and an activated phenotype of blood MAIT cell. These features persisted during remission suggesting a role for MAIT cells in the pathogenesis of AAV.

Emerging role of IL-17 and Th17 cells in systemic lupus erythematosus.

Despite the success of targeted therapies in managing immune-mediated inflammatory diseases (IMIDs) such as RA, IBDs, MS and psoriasis, unmet needs for such approach in SLE are widely recognized. In the past 2years, exciting insights supporting previous lines of evidence on the role of the IL-23/IL-17 axis in SLE have emerged. This is of particular importance as IL-17 blockers have now moved successfully into the clinical space, as illustrated in psoriasis and ankylosing spondylitis. However, recent fundamental studies also highlighted unexpected aspects of IL-17/Th17 biology whose comprehension may prevent disappointing results of IL-17 targeting such as those obtained in Crohn's disease. Therefore, establishing a current picture of the IL-17 pre-clinical situation in SLE is timely in order to plan future proof-of-concept studies in human.

Hydrocortisone prevents immunosuppression by interleukin-10+ natural killer cells after trauma-hemorrhage.

OBJECTIVE: Trauma induces a state of immunosuppression, which is responsible for the development of nosocomial infections. Hydrocortisone reduces the rate of pneumonia in patients with trauma. Because alterations of dendritic cells and natural killer cells play a central role in trauma-induced immunosuppression, we investigated whether hydrocortisone modulates the dendritic cell/natural killer cell cross talk in the context of posttraumatic pneumonia. DESIGN: Experimental study. SETTINGS: Research laboratory from an university hospital. SUBJECTS: Bagg Albino/cJ mice (weight, 20-24 g). INTERVENTIONS: First, in an a priori substudy of a multicenter, randomized, double-blind, placebo-controlled trial of hydrocortisone (200 mg/d for 7 d) in patients with severe trauma, we have measured the blood levels of five cytokines (tumor necrosis factor-α, interleukin-6, interleukin-10, interleukin-12, interleukin-17) at day 1 and day 8. In a second step, the effects of hydrocortisone on dendritic cell/natural killer cell cross talk were studied in a mouse model of posttraumatic pneumonia. Hydrocortisone (0.6 mg/mice i.p.) was administered immediately after hemorrhage. Twenty-four hours later, the mice were challenged with Staphylococcus aureus (7 × 10 colony-forming units). MEASUREMENTS AND MAIN RESULTS: Using sera collected during a multicenter study in patients with trauma, we found that hydrocortisone decreased the blood level of interleukin-10, a cytokine centrally involved in the regulation of dendritic cell/natural killer cell cluster. In a mouse model of trauma-hemorrhage-induced immunosuppression, splenic natural killer cells induced an interleukin-10-dependent elimination of splenic dendritic cell. Hydrocortisone treatment reduced this suppressive function of natural killer cells and increased survival of mice with posthemorrhage pneumonia. The reduction of the interleukin-10 level in natural killer cells by hydrocortisone was partially dependent on the up-regulation of glucocorticoid-induced tumor necrosis factor receptor-ligand (TNFsf18) on dendritic cell. CONCLUSIONS: These data demonstrate that trauma-induced immunosuppression is characterized by an interleukin-10-dependent elimination of dendritic cell by natural killer cells and that hydrocortisone improves outcome by limiting this immunosuppressive feedback loop.

Confocal laser endomicroscopy as predictive biomarker of clinical and endoscopic efficacy of vedolizumab in ulcerative colitis: The DETECT study.

AIMS: In patients with ulcerative colitis (UC), no biomarker is available to help the physician to choose the most suitable biotherapy. The primary objective of this pilot study was to assess the feasibility of identification of α4ß7- and TNF-expressing cells, to predict the response to vedolizumab using confocal laser endoscopy (CLE). METHODS: Patients with moderate-to-severe UC, naïve of biotherapy, received vedolizumab. Clinical evaluation was performed at each infusion. Endoscopic evaluation was performed before inclusion and at week 22. Fresh colonic biopsies were stained using FITC-labelled vedolizumab and Alexa fluor-labelled adalimumab and ex vivo dual-band CLE images were acquired. Blood samples were collected to measure trough concentrations of vedolizumab and to determine absolute counts of T and B cells subpopulations, NK cells and monocytes. RESULTS: Nineteen patients were enrolled in the study and received at least one dose of vedolizumab. Clinical remission and endoscopic improvement were observed in 58% of whom 5 patients (45%) had an endoscopic subscore of 0. In terms of clinical response and remission, endoscopic improvement and histologic response, FITC-conjugated vedolizumab staining tended to be higher in responder patients compared to non-responders at week 22. A threshold value of 6 positive FITC-vedolizumab staining areas detected by CLE seemed informative to discriminate the responders and non-responders. The results were similar in terms of clinical remission and endoscopic improvement with a sensitivity of 78% and a specificity of 85% (p = 0.05). Trough concentrations and blood immune cells were not associated with responses to vedolizumab. CONCLUSION: This pilot study demonstrate that dual-band CLE is feasible to detect α4ß7- and TNF-expressing cells. Positive α4ß7 staining seems to be associated with clinical and endoscopic remission in UC patients treated by anti-α4ß7-integrin, subject to validation by larger-scale studies. Clinical-trial.gov: NCT02878083.