Functional genomics in inborn errors of immunity.

Inborn errors of immunity (IEI) comprise a diverse spectrum of 485 disorders as recognized by the International Union of Immunological Societies Committee on Inborn Error of Immunity in 2022. While IEI are monogenic by definition, they illuminate various pathways involved in the pathogenesis of polygenic immune dysregulation as in autoimmune or autoinflammatory syndromes, or in more common infectious diseases that may not have a significant genetic basis. Rapid improvement in genomic technologies has been the main driver of the accelerated rate of discovery of IEI and has led to the development of innovative treatment strategies. In this review, we will explore various facets of IEI, delving into the distinctions between PIDD and PIRD. We will examine how Mendelian inheritance patterns contribute to these disorders and discuss advancements in functional genomics that aid in characterizing new IEI. Additionally, we will explore how emerging genomic tools help to characterize new IEI as well as how they are paving the way for innovative treatment approaches for managing and potentially curing these complex immune conditions.

Immunity to commensal skin fungi promotes psoriasiform skin inflammation.

Under steady-state conditions, the immune system is poised to sense and respond to the microbiota. As such, immunity to the microbiota, including T cell responses, is expected to precede any inflammatory trigger. How this pool of preformed microbiota-specific T cells contributes to tissue pathologies remains unclear. Here, using an experimental model of psoriasis, we show that recall responses to commensal skin fungi can significantly aggravate tissue inflammation. Enhanced pathology caused by fungi preexposure depends on Th17 responses and neutrophil extracellular traps and recapitulates features of the transcriptional landscape of human lesional psoriatic skin. Together, our results propose that recall responses directed to skin fungi can directly promote skin inflammation and that exploration of tissue inflammation should be assessed in the context of recall responses to the microbiota.

Keratinocyte-intrinsic MHCII expression controls microbiota-induced Th1 cell responses.

The cross-talk between the microbiota and the immune system plays a fundamental role in the control of host physiology. However, the tissue-specific factors controlling this dialogue remain poorly understood. Here we demonstrate that T cell responses to commensal colonization are associated with the development of organized cellular clusters within the skin epithelium. These organized lymphocyte clusters are surrounded by keratinocytes expressing a discrete program associated with antigen presentation and antimicrobial defense. Notably, IL-22-mediated keratinocyte-intrinsic MHC class II expression was required for the selective accumulation of commensal-induced IFN-γ, but not IL-17A-producing CD4+ T cells within the skin. Taking these data together, this work uncovers an unexpected role for MHC class II expression by keratinocytes in the control of homeostatic type 1 responses to the microbiota. Our findings have important implications for the understanding of the tissue-specific rules governing the dialogue between a host and its microbiota.

Cutaneous Kikuchi disease-like inflammatory pattern without lymph node involvement is associated with systemic disease and severe features in lupus erythematous: A case-control study.

INTRODUCTION: Kikuchi-Fujimoto disease (KFD) is a self-limited histiocytic necrotizing lymphadenitis sometimes affecting the skin. "Kikuchi disease-like inflammatory pattern" (KLIP) has been described in cutaneous lesions as similar pathological features in patients without lymph node involvement and as a potential clue for the diagnosis of lupus. We aimed to describe KLIP-associated clinical and immunological features in lupus patients with a retrospective case-control study. METHODS: Thirteen cases of KLIP were included as well as thirty-nine age- and sex-matched control lupus patients without KLIP. At the time of KLIP diagnosis, 4/13 patients (31%) had isolated cutaneous lupus erythematosus (CLE) and 9/13 had (69%) systemic lupus erythematosus (SLE) including 6 (46%) with severe haematological, lung, cardiac or renal disease. KLIP features were observed in skin biopsies of different clinical presentations. RESULTS: Compared with our control group, KLIP patients more frequently had SLE 9/13 (69%) versus 8/39 (21%) (OR 12.9; IC95% [2.86-58.2]; p = 0.0004) and more frequently severe SLE. Two out of four CLE exhibiting KLIP lesions (50%) developed severe SLE with cardiac or renal involvement after 12 and 24 months, respectively.Treatment with thalidomide 100 mg/day allowed rapid and complete clearance of cutaneous lesions in 6/6 KLIP patients. The need to use thalidomide tended to be more frequent in KLIP patients than in controls. CONCLUSION: Our study suggests that KLIP features in lupus skin lesions are associated with SLE and severe systemic features. Despite a limited number of isolated CLE patients with KLIP features in the skin, this observation may warrant closer follow-up on patients with a higher risk of developing SLE.

Effect of Ruxolitinib on Lung Function after Allogeneic Stem Cell Transplantation.

Ruxolitinib, a selective Janus kinase (JAK)1/2 inhibitor, has recently been proposed for steroid-refractory chronic graft-versus host disease (cGVHD) after allogeneic hematopoietic stem cell transplantation (HSCT), particularly in severe skin cGVHD. Lung function impairment is common in severe skin cGVHD through concomitant bronchiolitis obliterans syndrome (BOS) or restrictive lung disease (RLD) from skin sclerosis. To date, no treatment has shown a benefit on lung function in this context. We retrospectively assessed the effect of ruxolitinib on lung function in a cohort of 70 patients diagnosed with sclerotic-type skin cGVHD between March 2015 and April 2018. Among these patients, 36 received ruxolitinib. To handle confounding by indication bias, exposure groups were matched on the propensity score to receive ruxolitinib, incorporating age, myeloablative conditioning, total body irradiation, BOS, forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and tobacco use at the time of cohort entry, as well as the time from transplantation. The 1:1 matching used a greedy-matching algorithm with replacement, with a caliper of 0.10. FVC and FEV1 trajectories during follow-up were compared in the matched samples, using linear mixed-effects models. The median duration of follow-up of the 46 matched patients was 58 months (interquartile range, 32 to 84 months). Ten patients had an RLD (6 exposed, 4 unexposed), and 13 patients were diagnosed with BOS (8 exposed, 5 unexposed). FEV1 decreased significantly over time independent of exposure to ruxolitinib (P < .0001). The FEV1 trajectory was similar in the exposed patients and the unexposed patients (P = .11). In conclusion, ruxolitinib administration did not demonstrate any improvement in the course of respiratory function in allogeneic HSCT recipients with sclerotic-type skin cGVHD.

Transcobalamin receptor antibodies in autoimmune vitamin B12 central deficiency.

Vitamin B12 is critical for hematopoiesis and myelination. Deficiency can cause neurologic deficits including loss of coordination and cognitive decline. However, diagnosis relies on measurement of vitamin B12 in the blood, which may not accurately reflect the concentration in the brain. Using programmable phage display, we identified an autoantibody targeting the transcobalamin receptor (CD320) in a patient with progressive tremor, ataxia, and scanning speech. Anti-CD320 impaired cellular uptake of cobalamin (B12) in vitro by depleting its target from the cell surface. Despite a normal serum concentration, B12 was nearly undetectable in her cerebrospinal fluid (CSF). Immunosuppressive treatment and high-dose systemic B12 supplementation were associated with increased B12 in the CSF and clinical improvement. Optofluidic screening enabled isolation of a patient-derived monoclonal antibody that impaired B12 transport across an in vitro model of the blood-brain barrier (BBB). Autoantibodies targeting the same epitope of CD320 were identified in seven other patients with neurologic deficits of unknown etiology, 6% of healthy controls, and 21.4% of a cohort of patients with neuropsychiatric lupus. In 132 paired serum and CSF samples, detection of anti-CD320 in the blood predicted B12 deficiency in the brain. However, these individuals did not display any hematologic signs of B12 deficiency despite systemic CD320 impairment. Using a genome-wide CRISPR screen, we found that the low-density lipoprotein receptor serves as an alternative B12 uptake pathway in hematopoietic cells. These findings dissect the tissue specificity of B12 transport and elucidate an autoimmune neurologic condition that may be amenable to immunomodulatory treatment and nutritional supplementation.

Clinical and biological heterogeneity of multisystem inflammatory syndrome in adults following SARS-CoV-2 infection: a case series.

Importance: Multisystem inflammatory syndrome in adults (MIS-A) is a poorly understood complication of SARS-CoV-2 infection with significant morbidity and mortality. Objective: Identify clinical, immunological, and histopathologic features of MIS-A to improve understanding of the pathophysiology and approach to treatment. Design: Three cases of MIS-A following SARS-CoV-2 infection were clinically identified between October 2021 - March 2022 using the U.S. Centers for Disease Control and Prevention diagnostic criteria. Clinical, laboratory, imaging, and tissue data were assessed. Findings: All three patients developed acute onset cardiogenic shock and demonstrated elevated inflammatory biomarkers at the time of hospital admission that resolved over time. One case co-occurred with new onset Type 1 diabetes and sepsis. Retrospective analysis of myocardial tissue from one case identified SARS-CoV-2 RNA. All three patients fully recovered with standard of care interventions plus immunomodulatory therapy that included intravenous immunoglobulin, corticosteroids, and in two cases, anakinra. Conclusion: MIS-A is a severe post-acute sequela of COVID-19 characterized by systemic elevation of inflammatory biomarkers. In this series of three cases, we find that although clinical courses and co-existent diseases vary, even severe presentations have potential for full recovery with prompt recognition and treatment. In addition to cardiogenic shock, glucose intolerance, unmasking of autoimmune disease, and sepsis can be features of MIS-A, and SARS-CoV-2 myocarditis can lead to a similar clinical syndrome.

Murine model of colonization with fungal pathogen Candida auris to explore skin tropism, host risk factors and therapeutic strategies.

Candida auris is an emerging multi-drug-resistant human fungal pathogen. C. auris skin colonization results in environmental shedding, which underlies hospital transmissions, and predisposes patients to subsequent infections. We developed a murine skin topical exposure model for C. auris to dissect risk factors for colonization and to test interventions that might protect patients. We demonstrate that C. auris establishes long-term residence within the skin tissue compartment, which would elude clinical surveillance. The four clades of C. auris, with geographically distinct origins, differ in their abilities to colonize murine skin, mirroring epidemiologic findings. The IL-17 receptor signaling and specific arms of immunity protect mice from long-term C. auris skin colonization. We further determine that commonly used chlorhexidine antiseptic serves as a protective and decolonizing agent against C. auris. This translational model facilitates an integrated approach to develop strategies to combat the unfolding global outbreaks of C. auris and other skin-associated microbial pathogens.

Commensal-specific T cell plasticity promotes rapid tissue adaptation to injury.

Barrier tissues are primary targets of environmental stressors and are home to the largest number of antigen-experienced lymphocytes in the body, including commensal-specific T cells. We found that skin-resident commensal-specific T cells harbor a paradoxical program characterized by a type 17 program associated with a poised type 2 state. Thus, in the context of injury and exposure to inflammatory mediators such as interleukin-18, these cells rapidly release type 2 cytokines, thereby acquiring contextual functions. Such acquisition of a type 2 effector program promotes tissue repair. Aberrant type 2 responses can also be unleashed in the context of local defects in immunoregulation. Thus, commensal-specific T cells co-opt tissue residency and cell-intrinsic flexibility as a means to promote both local immunity and tissue adaptation to injury.

Eruption of lymphocyte recovery with atypical lymphocytes mimicking a primary cutaneous T-cell lymphoma: a series of 12 patients.

Eruption of lymphocyte recovery (ELR) may occur during bone marrow aplasia after chemotherapies. We reviewed the clinical and pathologic features of 12 patients (male-female ratio, 7:5; median age, 61 years) with an atypical ELR histologically mimicking a primary cutaneous T-cell lymphoma such as Sézary syndrome or CD30+ T-cell lymphoproliferative disorder. All the patients displayed an erythematous maculopapular eruption on the trunk and the limbs associated with fever. All but one had received a polychemotherapy for an acute myeloid leukemia (n=10) or a urothelial carcinoma (n=1) before the occurrence of the skin eruption. One had an autoimmune lymphoproliferative syndrome causing chronic agranulocytosis requiring granulocyte colony-stimulating factor injection. In all patients, the skin eruption was associated with a slight increase of white blood cell count followed by bone marrow recovery within the next weeks. All skin biopsies showed a dermal perivascular lymphocytic infiltrate containing atypical medium- to large-sized CD3+, CD4+ and CD8+, CD25+, ICOS+, PD1- lymphocytes with a strong CD30 expression in most instances (n=10), suggesting the recruitment of strongly activated T cells in the skin. In 6 patients, a diagnosis of CD30+ lymphoproliferative disorder or Sézary syndrome was proposed or suspected histopathologically, and only the clinical context allowed the diagnosis of ELR with a peculiar presentation with atypical lymphocytes. We describe a series of patients with an unusual form of ELR characterized by the presence of atypical activated T cells in the skin. On a practical ground, pathologists should be aware of this distinctive and misleading presentation.

A dysbiotic microbiome triggers TH17 cells to mediate oral mucosal immunopathology in mice and humans.

Periodontitis is one of the most common human inflammatory diseases, yet the mechanisms that drive immunopathology and could be therapeutically targeted are not well defined. Here, we demonstrate an expansion of resident memory T helper 17 (TH17) cells in human periodontitis. Phenocopying humans, TH17 cells expanded in murine experimental periodontitis through local proliferation. Unlike homeostatic oral TH17 cells, which accumulate in a commensal-independent and interleukin-6 (IL-6)-dependent manner, periodontitis-associated expansion of TH17 cells was dependent on the local dysbiotic microbiome and required both IL-6 and IL-23. TH17 cells and associated neutrophil accumulation were necessary for inflammatory tissue destruction in experimental periodontitis. Genetic or pharmacological inhibition of TH17 cell differentiation conferred protection from immunopathology. Studies in a unique patient population with a genetic defect in TH17 cell differentiation established human relevance for our murine experimental studies. In the oral cavity, human TH17 cell defects were associated with diminished periodontal inflammation and bone loss, despite increased prevalence of recurrent oral fungal infections. Our study highlights distinct functions of TH17 cells in oral immunity and inflammation and paves the way to a new targeted therapeutic approach for the treatment of periodontitis.

Usefulness of KIR3DL2 to Diagnose, Follow-Up, and Manage the Treatment of Patients with Sézary Syndrome.

Purpose: KIR3DL2 is a recently discovered marker of the malignant clonal cell population in Sézary syndrome. We intended to evaluate the expression of KIR3DL2 on blood T cells as a diagnostic, prognostic, and follow-up marker of Sézary syndrome.Experimental Design: Sixty-four patients diagnosed with Sézary syndrome were included in this monocentric study. We collected the percentage of KIR3DL2+ cells among CD3+ T cells, obtained by flow cytometry, and other classical diagnostic criteria for Sézary syndrome at diagnosis and during the follow-up.Results: Compared with the classical diagnostic factors, KIR3DL2 was the most sensitive diagnostic factor for Sézary syndrome. Univariate and multivariate analyses established that an eosinophil cell count >700/mm3 and a percentage of KIR3DL2+ cells within the CD3+ T cells >85% at diagnosis were associated with a significantly reduced disease-specific survival. Moreover, KIR3DL2 immunostaining allowed the assessment of treatment efficiency and specificity toward tumor cells, the detection of the residual disease following treatment, and the occurrence of relapse, even though patients clinically experienced complete remission and/or undetectable circulating Sézary cells by cytomorphologic analysis.Conclusions: We show that KIR3DL2 expression is the most sensitive diagnostic criterion of Sézary syndrome when compared with all other available biological criteria. It also represents the best independent prognostic factor for Sézary syndrome-specific death and the most relevant feature for the follow-up of Sézary syndrome, showing the invasion of the functional lymphocytes pool by Sézary cells. KIR3DL2 therefore represents a valuable tool for routine use as a clinical parameter at diagnosis, for prognosis and during patient follow-up. Clin Cancer Res; 23(14); 3619-27. ©2017 AACR.

Sequential nailfold videocapillaroscopy examinations have responsiveness to detect organ progression in systemic sclerosis.

OBJECTIVE: To determine the merit of nailfold videocapillaroscopy (NVC) to detect meaningful microvascular changes over time in patients with systemic sclerosis (SSc) and whether these changes are associated with overall disease progression and organ involvements. METHODS: A prospective cohort of 140 SSc patients was recruited over a 12-month period and was followed up on an annual basis for 3 years. Detailed NVC analysis was performed at inclusion and repeated annually. Disease progression and organ damage were defined according to validated definitions. RESULTS: Significant NVC changes were detected in 72 SSc patients (51%) during the follow-up period. Patients with incident or increased number of giant capillaries were less at risk to develop new digital ulcers (DU) [hazard ratio (HR) = 0.53, 95% confidence interval (CI): 0.07-0.93]. Loss of capillaries over time was confirmed as a robust and independent marker of organ progression. The reduction of the number of capillaries was associated with overall disease progression (HR = 4.35, 95% CI: 1.87-10.12), occurrence of new DU (HR = 5.33, 95% CI: 1.69-16.71), lung vascular progression (HR = 18.53, 95% CI: 1.28-78.33), progression of skin fibrosis (HR = 4.22, 95% CI: 1.24-14.36), and worsening of the Medsger severity score (HR = 5.26, 95% CI: 1.78-15.52). CONCLUSION: Significant NVC changes are observed in almost half of the patients with SSc during a follow-up of 3 years. Sequential NVC examinations have responsiveness to detect disease progression. Sequential NVC is confirmed of value to monitor SSc, as well as progressive loss of capillaries over time as a potential surrogate marker for disease progression.

Certolizumab pegol - A new therapeutic option for refractory disseminated pyoderma gangrenosum associated with Crohn's disease.

Systemic steroids, in association or not with cyclosporin, are indicated for the treatment of large or widespread Pyoderma gangrenosum (PG). We report the case of a 27-year-old woman with a 15-year history of severe Crohn's disease, who developed a severe and disseminated PG, refractory to multiple lines of treatment. Infliximab and adalimumab were contraindicated, either because of allergy or of ineffectiveness on Crohn's disease. The addition of certolizumab pegol to the baseline treatment, associating systemic steroids and tacrolimus, finally allowed the complete healing of PG. Oral prednisone was stopped and tacrolimus was decreased, without any cutaneous or digestive relapse. Certolizumab pegol could be an alternative therapy in the treatment of PG in case of intolerance or ineffectiveness of the other anti-tumor necrosis factor (anti-TNF) therapies.

Skin Telangiectasia and the Identification of a Subset of Systemic Sclerosis Patients With Severe Vascular Disease.

OBJECTIVE: Cutaneous telangiectasia (CT) are common in systemic sclerosis (SSc) patients, but their ability to stratify patients by risk is poorly known. We aimed to determine whether the number and size of CT were associated with the pattern of microvascular lesions assessed by nailfold videocapillaroscopy (NVC) and markers reflecting the severity of SSc-related vasculopathy. METHODS: We performed a cross-sectional study, including consecutive SSc patients over a 6-month period. We also considered 3 predefined subsets of patients according to the number of hand or face CT: absence, ≤10, or >10 hand or face CT (profuse CT). Pseudotumoral CT were defined as CT with >5 mm diameter. RESULTS: A total of 87 patients were included, of whom 75 (86%) had CT (27 with profuse and 19 with pseudotumoral CT). Profuse and pseudotumoral CT were both associated with capillary loss (P < 0.001 and P = 0.002, respectively) and severe neoangiogenesis (P = 0.015 and P = 0.041, respectively), 2 hallmarks of the late NVC pattern. In multivariate analysis, profuse CT were independently associated with past or current digital ulcers (odds ratio [OR] 2.95 [95% confidence interval (95% CI) 1.09-19.63]), and pseudotumoral CT were independently associated with the late NVC pattern (OR 4.84 [95% CI 1.32-26.19]) and with precapillary pulmonary hypertension (OR 12.60 [95% CI 1.68-94.53]). CONCLUSION: We demonstrate that the number and size of CT are associated with the most severe NVC pattern. In addition, profuse and pseudotumoral CT identify a subset of patients with a more severe vascular phenotype. Further prospective studies should determine whether CT number and size could serve as an early clinical biomarker for the development of severe vascular disease.

Mechanisms Underpinning Increased Plasma Creatinine Levels in Patients Receiving Vemurafenib for Advanced Melanoma.

CONTEXT: Serum creatinine has been reported to increase in patients receiving Vemurafenib, yet neither the prevalence nor the mechanism of this adverse event are known. OBJECTIVE: We aimed to evaluate the frequency and the mechanisms of increases in plasma creatinine level in patients receiving Vemurafenib for advanced melanoma. METHODS: We performed a retrospective monocentric study including consecutive patients treated with Vemurafenib for an advanced melanoma. We collected clinical and biological data concerning renal function before introduction of Vemurafenib and in the course of monthly follow-up visits from March 2013 to December 2014. Cystatin C-derived glomerular filtration rate was evaluated before and after Vemurafenib initiation, as increase in serum cystatin C is specific to a decrease in the glomerular filtration rate. We also performed thorough renal explorations in 3 patients, with measurement of tubular secretion of creatinine before and after Vemurafenib initiation and a renal biopsy in 2 patients. RESULTS: 70 patients were included: 97% of them displayed an immediate, and thereafter stable, increase in creatinine (+22.8%) after Vemurafenib initiation. In 44/52 patients in whom Vemurafenib was discontinued, creatinine levels returned to baseline. Serum cystatin C increased, although proportionally less than serum creatinine, showing that creatinine increase under vemurafenib was indeed partly due to a renal function impairment. In addition, renal explorations demonstrated that Vemurafenib induced an inhibition of creatinine tubular secretion. CONCLUSION: Thus, Vemurafenib induces a dual mechanism of increase in plasma creatinine with both an inhibition of creatinine tubular secretion and slight renal function impairment. However, this side effect is mostly reversible when Vemurafenib is discontinued, and should not lead physicians to discontinue the treatment if it is effective.