TH17 Cells in Autoimmunity and Immunodeficiency: Protective or Pathogenic?

In 2005 a newly discovered T helper cell subset that secreted interleukin (IL)-17 became the center of attention in immunology. Initial studies painted Th17 cells as the culprit for destruction in many different autoimmune and auto-inflammatory diseases. Subsequently, the discovery of patients with primary immunodeficiencies in the IL-17 pathway taught us that Th17 cells have a critical role in defense against certain fungal and bacterial infections. Moreover, the paradoxical exacerbation of Crohn’s disease in the clinical trials of a Secukinumab (AIN457), a fully human neutralizing antibody to IL-17A, has cast into doubt a universal pro-inflammatory and harmful role for Th17 cells. Evidence now suggests that depending on the environment Th17 cells can alter their differentiation program, ultimately giving rise to either protective or pro-inflammatory cells. In this review we will summarize the evidence from patients with immunodeficiencies, autoimmune, or auto-inflammatory diseases that teaches us how the pro-inflammatory versus protective function of Th17 cells varies within the context of different human diseases

Two cases of carbonic anhydrase va deficiency—an ultrarare metabolic decompensation syndrome presenting with hyperammonemia, lactic acidosis, ketonuria, and good clinical outcome

The combination of neonatal hyperammonemia, lactic acidosis, ketonuria, and hypoglycemia is pathognomonic for carbonic anhydrase VA (CA-VA) deficiency. We present two cases of this rare inborn error of metabolism. Both newborns with South Asian ancestry presented with a metabolic decompensation characterized by hyperammonemia, lactic acidosis and ketonuria; one also had hypoglycemia. Standard metabolic investigations (plasma amino acids, acylcarnitine profile, and urine organic acids) were not indicative of a specific organic aciduria or fatty acid oxidation defect but had some overlapping features with a urea cycle disorder (elevated glutamine, orotic acid, and low argi-nine). Hyperammonemia was treated initially with nitrogen scavenger therapy and carglumic acid. One patient required hemodialysis. Both have had a favorable long-term prognosis after their initial metabolic decompensation. Genetic testing confirmed the diagnosis of carbonic anhydrase VA (CA-VA) deficiency due to biallelic pathogenic variants in CA5A. These cases are in line with 15 cases previously described in the literature, making the phenotypic presentation pathognomonic for this ultrarare (potentially underdiagnosed) inborn error of metabolism with a good prognosis

CERT1 mutations perturb human development by disrupting sphingolipid homeostasis

Neural differentiation, synaptic transmission, and action potential propagation depend on membrane sphingolipids, whose metabolism is tightly regulated. Mutations in the ceramide transporter CERT (CERT1), which is involved in sphingolipid biosynthesis, are associated with intellectual disability, but the pathogenic mechanism remains obscure. Here, we characterize 31 individuals with de novo missense variants in CERT1. Several variants fall into a previously uncharacterized dimeric helical domain that enables CERT homeostatic inactivation, without which sphingolipid production goes unchecked. The clinical severity reflects the degree to which CERT autoregulation is disrupted, and inhibiting CERT pharmacologically corrects morphological and motor abnormalities in a Drosophila model of the disease, which we call ceramide transporter (CerTra) syndrome. These findings uncover a central role for CERT autoregulation in the control of sphingolipid biosynthetic flux, provide unexpected insight into the structural organization of CERT, and suggest a possible therapeutic approach for patients with CerTra syndrome.This work was supported by the National Institute of Neurological Disorders and Stroke (NINDS), NIH (R01NS109858, to VAG); the Paul A. Marks Scholar Program at the Columbia University Vagelos College of Physicians and Surgeons (to VAG); a TIGER grant from the TAUB Institute at the Columbia Vagelos College of Physicians and Scientists (to VAG); the Swiss National Science Foundation (SNF 31003A-179371, to TH); the European Joint Program on Rare Diseases (EJP RD+SNF 32ER30-187505, to TH); the Swiss Cancer League (KFS-4999-02-2020, to GD); the EPFL institutional fund (to GD); the Kristian Gerhard Jebsen Foundation (to GD); the Swiss National Science Foundation (SNSF) (310030_184926, to GD); the Swiss Foundation for Research on Muscle Disease (FSRMM, to MAL); the Natural Science and Engineering Research Council of Canada (Discovery Grant 2020-04241, to JEB); the Italian Ministry of Health Young Investigator Grant (GR-2011-02347754, to EL); the Fondazione Istituto di Ricerca Pediatrica – Città della Speranza (18-04, to EL); the Wroclaw Medical University (SUB.E160.21.004, to RS); the National Science Centre, Poland (2017/27/B/NZ5/0222, to RS); Telethon Undiagnosed Diseases Program (TUDP) (GSP15001); the Temple Street Foundation/Children’s Health Foundation Ireland (RPAC 19-02, to IK); the Deutsche Forschungsgemeinschaft (DFG) (PO2366/2–1, to BP); the Instituto de Salud Carlos III, Spain (to ELM, EBS, and BMD); the National Natural Science Foundation of China (81871079 and 81730036, to HG and KX); and the National Institutes of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH (R01 DK115574, to SSC).The DEFIDIAG study is funded by grants from the French Ministry of Health in the framewok of the national French initiative for genomic medicine. The funders were not involved in the study design, data acquisition, analysis, or writing of the manuscript. Funding for the DECIPHER project was provided by Wellcome. The DDD study presents independent research commissioned by the Health Innovation Challenge Fund (grant number HICF-1009-003), a parallel funding partnership between Wellcome and the Department of Health, and the Wellcome Sanger Institute (grant number WT098051). The views expressed in this publication are those of the author(s) and not necessarily those of Wellcome or the Department of Health. The study has UK Research Ethics Committee approval (10/H0305/83, granted by the Cambridge South REC, and GEN/284/12, granted by the Republic of Ireland REC). The research team acknowledges the support of the National Institute for Health Research, through the Comprehensive Clinical Research Network.S

Ustekinumab for type 1 diabetes in adolescents: a multicenter, double-blind, randomized phase 2 trial

Immunotherapy targeting the autoimmune process in type 1 diabetes (T1D) can delay the loss of β-cells but needs to have minimal adverse effects to be an adjunct to insulin in the management of T1D. Ustekinumab binds to the shared p40 subunit of interleukin (IL)-12 and IL-23, targeting development of T helper 1 cells and T helper 17 cells (TH1 and TH17 cells) implicated in the pathogenesis of T1D. We conducted a double-blind, randomized controlled trial of ustekinumab in 72 adolescents aged 12–18 years with recent-onset T1D. Treatment was well tolerated with no increase in adverse events. At 12 months, β-cell function, measured by stimulated C-peptide, was 49% higher in the intervention group (P = 0.02), meeting the prespecified primary outcome. Preservation of C-peptide correlated with the reduction of T helper cells co-secreting IL-17A and interferon-γ (TH17.1 cells, P = 0.04) and, in particular, with the reduction in a subset of TH17.1 cells co-expressing IL-2 and granulocyte–macrophage colony-stimulating factor (IL-2+ GM-CSF+ TH17.1 cells, P = 0.04). A significant fall in β-cell-targeted (proinsulin-specific) IL-17A-secreting T cells was also seen (P = 0.0003). Although exploratory, our data suggest a role for an activated subset of TH17.1 cells in T1D that can be targeted with minimal adverse effects to reduce C-peptide loss, which requires confirmation in a larger study. (International Standard Randomised Controlled Trial Number Registry: ISRCTN 14274380)

CERT1 mutations perturb human development by disrupting sphingolipid homeostasis

Neural differentiation, synaptic transmission, and action potential propagation depend on membrane sphingolipids, whose metabolism is tightly regulated. Mutations in the ceramide transporter CERT (CERT1), which is involved in sphingolipid biosynthesis, are associated with intellectual disability, but the pathogenic mechanism remains obscure. Here, we characterize 31 individuals with de novo missense variants in CERT1. Several variants fall into a previously uncharacterized dimeric helical domain that enables CERT homeostatic inactivation, without which sphingolipid production goes unchecked. The clinical severity reflects the degree to which CERT autoregulation is disrupted, and inhibiting CERT pharmacologically corrects morphological and motor abnormalities in a Drosophila model of the disease, which we call ceramide transporter (CerTra) syndrome. These findings uncover a central role for CERT autoregulation in the control of sphingolipid biosynthetic flux, provide unexpected insight into the structural organization of CERT, and suggest a possible therapeutic approach for patients with CerTra syndrome

Genetic variants in the IL-2 pathway disrupt the immune balance between regulatory T cells and Th17 cells in human type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease resulting from the destruction of insulin-producing β cells by autoreactive lymphocytes. CD4+FOXP3+ T regulatory cells (Tregs) are essential for immune tolerance, and murine studies suggest that their dysfunction can lead to T1D. Tregs require the cytokine interleukin-2 (IL-2) for maintenance of their suppressive function, and polymorphic variants in IL-2/IL-2R pathway genes are associated with T1D. Tregs can display plasticity by converting into Th17 cells, and intermediate FOXP3+IL-17+ cells have been identified. We hypothesized that pancreatic β cell destruction in T1D is driven by conversion of autoreactive Treg cells into a Th17 phenotype due to defective Treg IL-2 signaling in T1D subjects, who have polymorphic variants in the IL2RA gene. We assessed by flow cytometry the proportion of Treg and Th17 subsets in peripheral blood mononuclear cells from T1D subjects. The subjects were genotyped to determine whether they had the T1D-associated IL2RArs3118470 CC risk haplotype. Samples from T1D subjects were also obtained before the onset of disease. We found that Tregs are potentially transitioning towards a Th17 phenotype in recent-onset T1D subjects as they have an elevated proportion of FOXP3+IL-17+ cells and Th17 cells in their peripheral blood. We went on to show that T1D subjects with the T1D-associated IL2RArs3118470 CC risk haplotype have Treg cells with IL-2 signaling deficits and an increase in the proportion of IL-17+FOXP3+ cells in their peripheral blood at diagnosis. We did not find changes in the overall proportions of Tregs and Th17 cells in T1D subjects sampled before the onset of diagnosis. However, we observed a subset of CD39-expressing Treg cells were reduced in proportion before disease onset and could act as a biomarker of T1D. In conclusion, we show that defective IL-17-secreting Tregs are involved with T1D pathogenesis in a genetically identifiable subset of subjects, and provide a rationale for the treatment of T1D with therapeutics that target the IL-17 pathway.Medicine, Faculty ofPathology and Laboratory Medicine, Department ofGraduat

Factors affecting the quality of cryoprecipitate

Background: Many variables affect the quality of cryoprecipitate (CRYO). We investigated the effect of freezing techniques and ABO blood groups on the quality of CRYO with respect to factor VIII: C and fibrinogen levels. Materials and Methods: Ninety-six whole blood units each collected from in-house (Group I) and blood donation camps outside the hospital premises (Group II) were processed for CRYO preparation. Within each group, half the number of plasma units was frozen using blast freezer and another half using the conventional freezer. The CRYOs from blood groups A, B, and O were equally distributed, i.e. 32 within each of the Groups I and II. The fibrinogen and factor VIII: C levels in CRYO were analyzed using single-stage clotting assay. Results: In Group I, the mean ± standard deviation percentage recovery of factor VIII levels in CRYO prepared using the conventional freezer and blast freezer were 58.5% ±16.2% and 66.7% ±16.4%, respectively, and in Group II, it was 55.3% ±17.6% and 70.4% ±13.4%, respectively. Recovery of factor VIII was higher in CRYO prepared using blast freezer than that of CRYO prepared using conventional freezer (P < 0.000). In Group II, CRYOs prepared using blast freezer had higher percent recovery of fibrinogen than that of Group I. In both the groups, the mean factor VIII levels in blood group A were higher than that of factor VIII levels in the blood group O CRYO. Conclusion: The factor VIII recovery in CRYO improves significantly with higher baseline factor VIII: C levels, blood group A donor, and rapid freezing using blast freezer. Rapid freezing also increases the fibrinogen yield

Direct antiglobulin test positivity in multi-transfused thalassemics

Introduction: Red cell allo- and auto-immunization is a well recognized problem in multi-transfused thalassemic patients. We conducted this study on 301 multi-transfused thalassemic patients under the Thalassemia Transfusion Programme of Advanced Pediatric Centre of PGIMER. Aims and Objectives: The study was designed to determine the frequency of alloimmunization and autoimmunization in multi-transfused thalassemic patients and to establish the specificity of alloantibody to red cell antigens, if alloimmunization is detected. Materials and Methods: The antibody screening was performed by the conventional tube technique using commercially available three cell screening panel (Diamed Switzerland) by saline, low ionic strength solution (LISS) and albumin indirect antiglobulin test (IAT). Samples with alloantibodies were then tested with red cell identification panel to determine the alloantibody specificity. Autoantibody screening was performed by direct antiglobulin test (DAT) during pre-transfusion testing. Results: Of the 301 patients, 52 (17.28%) were found to have antibodies (-allo and –autoantibodies). A total of 11 red cell alloantibodies were detected in 10 patients and the specificities were anti-Kell in 6(54.5%), anti-D in 2(18.2%), anti-c in 1(9.1%) and a combination of anti-E (9.1%) and anti-Jkb in 1 (9.1%) patients. DAT was positive in 48 (15.9%) patients. The frequency of autoantibody was significantly higher in alloimmunized group as compared to non-alloimmunized group (60% V/s 14.4%). Also, the pre-transfusion hemoglobin was significantly lower in the immunized group (8.5 gm/dl V/s 9.0 gm/dl; p=0.03) than the non-immunized group. Conclusion: Based on these observations, we suggest antigen typing of all thalassemia major patients for ABO, Rh and Kell antigens before initiating transfusion therapy. Also, screening for allo- and auto-antibodies at regular intervals should be done prior to each transfusion