Lucienne Chatenoud

Organ transplantation standard of care relies on lifelong immunosuppression, increasing infection and malignancy risks. An emerging approach using Chimeric Antigen Receptor Regulatory T cells (CAR-Tregs) targeting donor antigens, allows the suppression of alloimmune responses while preserving protective immunity. However, transplant recipients harbor a substantial pool of alloreactive memory T-cells, limiting CAR-Tregs tolerance-promoting effect. To address this challenge, our strategy combines selective depletion of activated T-cells, using non-mitogenic CD3 antibody therapy, with HLA-A2-targeted-CAR-Treg therapy. We established that T-cell receptor alpha chain ( TRAC ) deletion does not impair CAR-Treg antigen-specific activation, expansion, or their transcriptomic, phenotypic, epigenetic, and functional profiles. TRAC -/-CAR-Tregs exhibit robust protection from CD3 antibody depletion in circulation and peripheral tissues, whereas most TRAC +/+CAR-T cells are eliminated. Importantly, TRAC +/+CAR-T cells that escape CD3 antibody mediated depletion exhibit a transcriptomic signature consistent with T-cell exhaustion. Our findings demonstrate that CD3 antibody therapy provides an in vivo survival advantage to TRAC -/-CAR-Tregs, thereby shifting the immune balance toward regulation. This approach might enhance the translational potential of CAR-Treg therapy by reducing the required cell dose needed for clinical efficacy.

Aims/hypothesis: In the PROTECT randomised trial, teplizumab demonstrated significantly greater beta cell function preservation vs placebo in the intent-to-treat (ITT) population. Analyses of the pre-specified per-protocol (PP) population and PP subgroups are presented to further evaluate the efficacy of teplizumab. Methods: Participants aged 8–17 years with stage 3 type 1 diabetes with a peak stimulated C-peptide level ≥0.2 nmol/l (ITT population: N =328) were randomised 2:1 to receive two 12-day courses of teplizumab or placebo intravenously. Participants with n =180; placebo, n =95). At week 78, the primary endpoint of the least squares (LS) mean difference in change of stimulated C-peptide concentration from baseline between teplizumab and placebo was 0.14 nmol/l (95% CI 0.10, 0.18; p −1 day ⁻¹ ; 95% CI –0.26, –0.08; p p <0.05) vs placebo. In subgroup analyses, treatment with teplizumab resulted in higher C-peptide levels compared with placebo, regardless of HLA-DR3/HLA-DR4 presence or baseline type 1 diabetes autoantibodies. Conclusions/interpretation: Teplizumab treatment per protocol led to greater beta cell function preservation, greater TIR and lower exogenous insulin use compared with placebo. Beta cell function preservation was maintained irrespective of HLA subtype or the presence of type 1 diabetes autoantibodies. Trial registration: ClinicalTrials.gov NCT03875729 Funding: The study was funded by Provention Bio, a Sanofi company

In November 2022, teplizumab became the first drug approved to delay the course of any autoimmune disease and to change the course of type 1 diabetes (T1D) since the discovery of insulin. The path to its approval took more than 30 years with both successes and failures along the way that would have normally led to its abandonment in other circumstances. Development of the drug was based on studies in preclinical models and parallels efforts in transplantation. From a series of innovative adaptations in response to issues related to adverse events and immunogenicity, humanized Fc receptors (FcR) nonbinding antibodies were developed with improved clinical outcomes and safety as well as new mechanisms. Importantly, as a result of these developments, teplizumab has been able to achieve efficacy over extended periods of time without global immune suppression. The approval of teplizumab represents a significant first step toward achieving escape from T1D and, in the future, reversal of the disease.

Introduction: The therapeutic interest of targeting B-cell activating factor (BAFF) in Sjögren’s disease (SjD) can be suspected from the results of two phase II clinical trials but has not been evaluated in an animal model of the disease. We aimed to evaluate the therapeutic efficacy of this strategy on dryness and salivary gland (SG) infiltrates in the NOD mouse model of SjD. Material and methods: Female NOD mice between ages 10 and 18 weeks were treated with a BAFF-blocking monoclonal antibody, Sandy-2 or an isotype control. Dryness was measured by the stimulated salivary flow. Salivary lymphocytic infiltrates were assessed by immunohistochemistry. Blood, SGs, spleen and lymph-node lymphocyte subpopulations were analysed by flow cytometry. SG mRNA expression was analysed by transcriptomic analysis. Results: BAFF inhibition significantly decreased SG lymphocytic infiltrates, which was inversely correlated with salivary flow. The treatment markedly decreased B-cell number in SGs, blood, lymph nodes and spleen and increased Foxp3⁺ regulatory and CD3⁺CD4⁻CD8⁻ double negative T-cell numbers in SGs. Conclusion: A monoclonal antibody blocking BAFF and depleting B cells had therapeutic effectiveness in the NOD mouse model of SjD. The increase in regulatory T-lymphocyte populations might underlie the efficacy of this treatment.

Genetic association studies of type 1 diabetes (T1D) in humans, and in congenic non-obese diabetic (NOD) mice harboring DNA segments from T1D-resistant mice, face the challenge of assigning causation to specific gene variants among many within loci that affect disease risk. Here, we created random germline mutations in NOD/NckH mice and used automated meiotic mapping to identify mutations modifying T1D incidence and age of onset. In contrast with association studies in humans or congenic NOD mice, we analyzed a relatively small number of genetic changes in each pedigree, permitting implication of specific mutations as causative. Among 844 mice from 14 pedigrees bearing 594 coding/splicing changes, we identified seven mutations that accelerated T1D development, and five that delayed or suppressed T1D. Eleven mutations affected genes not previously known to influence T1D (Xpnpep1, Herc1, Srrm2, Rapgef1, Ppl, Zfp583, Aldh1l1, Col6a1, Ccdc13, Cd200r1, Atrnl1). A suppressor mutation in Coro1a validated the screen. Mutagenesis coupled with automated meiotic mapping can detect genes in which allelic variation influences T1D susceptibility in NOD mice. Variation of some of the orthologous/paralogous genes may influence T1D susceptibility in humans.

Insulin-dependent or type 1 diabetes (T1D) is a polygenic autoimmune disease. In humans, more than 60 loci carrying common variants that confer disease susceptibility have been identified by genome-wide association studies, with a low individual risk contribution for most variants excepting those of the major histocompatibility complex (MHC) region (40 to 50% of risk); hence the importance of missing heritability due in part to rare variants. Nonobese diabetic (NOD) mice recapitulate major features of the human disease including genetic aspects with a key role for the MHC haplotype and a series of Idd loci. Here we mapped in NOD mice rare variants arising from genetic drift and significantly impacting disease risk. To that aim we established by selective breeding two sublines of NOD mice from our inbred NOD/Nck colony exhibiting a significant difference in T1D incidence. Whole-genome sequencing of high (H)- and low (L)-incidence sublines (NOD/Nck^H and NOD/Nck^L) revealed a limited number of subline-specific variants. Treating age of diabetes onset as a quantitative trait in automated meiotic mapping (AMM), enhanced susceptibility in NOD/Nck^H mice was unambiguously attributed to a recessive missense mutation of Dusp10, which encodes a dual specificity phosphatase. The causative effect of the mutation was verified by targeting Dusp10 with CRISPR-Cas9 in NOD/Nck^L mice, a manipulation that significantly increased disease incidence. The Dusp10 mutation resulted in islet cell down-regulation of type I interferon signature genes, which may exert protective effects against autoimmune aggression. De novo mutations akin to rare human susceptibility variants can alter the T1D phenotype. Significance The vast majority of autoimmune diseases are polygenic, and causal loci uncovered by genetic-mapping studies explain only a minority of the heritable contribution to trait variation. Multiple explanations for this missing heritability include rare meaningful variants, rare copy number variations or deletions, epistasis, epigenetics, disease heterogeneity, and rare or infrequent variants that segregate within individual families (even within monozygotic twins). Here we demonstrate that experimental models of spontaneous autoimmune diseases may be invaluable tools to map rare germline variants impacting disease susceptibility traits. We identified a variant of the dual-specificity phosphatase 10 encoding gene that accelerates disease in an autoimmune type 1 diabetes model, the nonobese diabetic mouse.

Mast cells are key actors of innate immunity and Th2 adaptive immune response which counterbalance Th1 response, critical for anti-viral immunity. Clonal Mast Cells Activation Disorders (cMCADs) such as mastocytosis and clonal mast cells activation syndrome are characterized by an abnormal mast cells accumulation and/or activation. No data have been published on the anti-viral immune response of patients with cMCADs. The aims of the study were to collected, in a comprehensive way, outcomes of cMCADs patients who experienced a biologically-proven COVID-19 and to characterize both anti-endemic coronaviruses and specific anti-SARS-CoV-2 immune responses in these patients. Clinical follow-up and outcome data were collected prospectively for one year within the French rare disease network CEREMAST encompassing patients from all over the country. Anti-SARS-CoV-2 and anti-endemic coronaviruses specific T-cells were assessed with an enzyme-linked immunospot assay (EliSpot) and anti-SARS-CoV-2 humoral response with dosage of circulating levels of specific IgG, IgA and neutralizing antibodies. Overall, 32 cMCADs patients were identified. None of them required non-invasive or mechanical ventilation; two patients were hospitalized to receive oxygen and steroid therapy. In 21 patients, a characterization of the SARS-CoV-2-specific immune response has been performed. A majority of patients showed a high proportion of circulating SARS-CoV-2-specific interferon (IFN)-γ producing T-cells and high levels of anti-Spike IgG antibodies with neutralizing activity. In addition, no defects in anti-endemic coronaviruses responses were found in patients with cMCADs compared to non-cMCADs controls. Patients with cMCADs frequently showed a spontaneous IFN-γ T-cell production in absence of any stimulation that correlated with circulating basal tryptase levels, a marker of mast cells burden. These findings underscore that patients with cMCADs might be not at risk of severe COVID-19 and the spontaneous IFN-γ production might explain this observation. Author Summary Mast cells are immune cells involved in many biological processes including the anti-microbial response. However, previous studies suggest that mast cells may have a detrimental role in the response against viruses such as SARS-CoV-2, responsible for COVID-19. When a mutation occurs in mast cells, it can lead to a group of diseases called clonal mast cells activation disorders (cMCADs), characterized by deregulated activation of these cells. Hence, patients with cMCADs might be more susceptible to severe COVID-19 than general population. We therefore conducted a 1-year study in France to collect data from all cMCADs patients included in the CEREMAST rare disease French network and who experienced COVID-19. Interestingly, we did not find any severe COVID-19 (i.e. requiring non-invasive or mechanical ventilation) in spite of well-known risk factors for severe COVID-19 in a part of cMCADs patients. We then have studied the immune response against SARS-CoV-2 and other endemic coronaviruses in these patients. We did not observe any abnormalities in the immune response either at the level of T and B lymphocytes. These findings underscore that these patients might not be at risk of severe COVID-19 as one might have feared.

Here we report the isolation by selective breeding of two sublines of Non-Obese Diabetic (NOD) mice exhibiting a significant difference in the incidence of autoimmune type 1 diabetes (T1D). Whole genome sequencing of the NOD/Nck ^H (high T1D incidence) and NOD/Nck ^L (low T1D incidence) revealed the presence of a limited number of variants specific to each subline. Treating the age of T1D onset as a quantitative trait and using automated meiotic mapping (AMM), enhanced susceptibility in the NOD/Nck ^H subline was unambiguously attributed to a recessive allele of Dusp10 which encodes a dual specificity phosphatase. The causative effect of the mutation was verified with a high level of confidence by targeting Dusp10 with CRISPR/Cas9 in NOD/Nck ^L mice: in these animals a higher incidence of diabetes was observed. Expression of wild-type Dusp10 correlated with higher levels of surface PD-L1 in the islets of NOD/Nck ^L mice.

Heterozygous missense mutations in coatomer protein subunit α, COPA, cause a syndrome overlapping clinically with type I IFN-mediated disease due to gain-of-function in STING, a key adaptor of IFN signaling. Recently, increased levels of IFN-stimulated genes (ISGs) were described in COPA syndrome. However, the link between COPA mutations and IFN signaling is unknown. We observed elevated levels of ISGs and IFN-α in blood of symptomatic COPA patients. In vitro, both overexpression of mutant COPA and silencing of COPA induced STING-dependent IFN signaling. We detected an interaction between COPA and STING, and mutant COPA was associated with an accumulation of ER-resident STING at the Golgi. Given the known role of the coatomer protein complex I, we speculate that loss of COPA function leads to enhanced type I IFN signaling due to a failure of Golgi-to-ER STING retrieval. These data highlight the importance of the ER–Golgi axis in the control of autoinflammation and inform therapeutic strategies in COPA syndrome.