Immune dysregulation in human subjects with heterozygous germline mutations in CTLA4

Genomic profiling of T-cell activation suggests increased sensitivity of memory T cells to CD28 costimulation

T-cell activation is a critical driver of immune responses. The CD28 costimulation is an essential regulator of CD4 T-cell responses, however, its relative importance in naive and memory T cells is not fully understood. Using different model systems, we observe that human memory T cells are more sensitive to CD28 costimulation than naive T cells. To deconvolute how the T-cell receptor (TCR) and CD28 orchestrate activation of human T cells, we stimulate cells using varying intensities of TCR and CD28 and profiled gene expression. We show that genes involved in cell cycle progression and division are CD28-driven in memory cells, but under TCR control in naive cells. We further demonstrate that T-helper differentiation and cytokine expression are controlled by CD28. Using chromatin accessibility profiling, we observe that AP1 transcriptional regulation is enriched when both TCR and CD28 are engaged, whereas open chromatin near CD28-sensitive genes is enriched for NF-kB motifs. Lastly, we show that CD28-sensitive genes are enriched in GWAS regions associated with immune diseases, implicating a role for CD28 in disease development. Our study provides important insights into the differential role of costimulation in naive and memory T-cell responses and disease susceptibility.

Novel human immunomodulatory T cell receptors and their double-edged potential in autoimmunity, cardiovascular disease and cancer

In the last decade, approaches based on T cells and their immunomodulatory receptors have emerged as a solid improvement in treatments for various types of cancer. However, the roles of these molecules in the therapeutic context of autoimmune and cardiovascular diseases are still relatively unexplored. Here, we review the best known and most commonly used immunomodulatory T cell receptors in clinical practice (PD-1 and CTLA-4), along with the rest of the receptors with known functions in animal models, which have great potential as modulators in human pathologies in the medium term. Among these other receptors is the receptor CD69, which has recently been described to be expressed in mouse and human T cells in autoimmune and cardiovascular diseases and cancer. However, inhibition of these receptors individually or in combination by drugs or monoclonal antibodies generates a loss of immunological tolerance and can trigger multiple autoimmune disorders in different organs and immune-related adverse effects. In the coming decades, knowledge on the functions of different immunomodulatory receptors will be pivotal for the development of new and better therapies with less harmful side effects. In this review, we discuss the roles of these receptors in the control of immunity from a perspective focused on therapeutic potential in not only cancer but also autoimmune diseases, such as systemic lupus erythematosus, autoimmune diabetes and rheumatoid arthritis, and cardiovascular diseases, such as atherosclerosis, acute myocardial infarction, and myocarditis.

COVID-19, varying genetic resistance to viral disease and immune tolerance checkpoints

Coronavirus disease 2019 (COVID‐19) is a zoonosis like most of the great plagues sculpting human history, from smallpox to pandemic influenza and human immunodeficiency virus. When viruses jump into a new species the outcome of infection ranges from asymptomatic to lethal, historically ascribed to “genetic resistance to viral disease.” People have exploited these differences for good and bad, for developing vaccines from cowpox and horsepox virus, controlling rabbit plagues with myxoma virus and introducing smallpox during colonization of America and Australia. Differences in resistance to viral disease are at the core of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) crisis, yet our understanding of the mechanisms in any interspecies leap falls short of the mark. Here I review how the two key parameters of viral disease are countered by fundamentally different genetic mechanisms for resistance: (1) virus transmission, countered primarily by activation of innate and adaptive immune responses; and (2) pathology, countered primarily by tolerance checkpoints to limit innate and adaptive immune responses. I discuss tolerance thresholds and the role of CD8 T cells to limit pathological immune responses, the problems posed by tolerant superspreaders and the signature coronavirus evasion strategy of eliciting only short‐lived neutralizing antibody responses. Pinpointing and targeting the mechanisms responsible for varying pathology and short‐lived antibody were beyond reach in previous zoonoses, but this time we are armed with genomic technologies and more knowledge of immune checkpoint genes. These known unknowns must now be tackled to solve the current COVID‐19 crisis and the inevitable zoonoses to follow.

Histology of Interstitial Lung Disease in Common Variable Immune Deficiency

Interstitial lung disease (ILD) is an important non-infectious complication in several primary immune deficiencies. In common variable immune deficiency (CVID) it is associated with complex clinical phenotypes and adverse outcomes. The histology of ILD in CVID is heterogeneous and mixed patterns are frequently observed within a single biopsy, including non-necrotising granulomatous inflammation, lymphoid interstitial pneumonitis, lymphoid hyperplasia, follicular bronchiolitis, organizing pneumonia, and interstitial fibrosis; ILD has to be differentiated from lymphoma. The term granulomatous-lymphocytic interstitial lung disease (GLILD), coined to describe the histopathological findings within the lungs of patients with CVID with or without multisystem granulomata, is somewhat controversial as pulmonary granulomata are not always present on histology and the nature of infiltrating lymphocytes is variable. In this mini review we summarize the literature on the histology of CVID-related ILD and discuss some of the factors that may contribute to the inter- and intra- patient variability in the histological patterns reported. Finally, we highlight areas for future development. In particular, there is a need for standardization of histological assessments and reporting, together with a better understanding of the immunopathogenesis of CVID-related ILD to resolve the apparent heterogeneity of ILD in this setting and guide the selection of rational targeted therapies in different patients.

Persistent Activation of Innate Immunity in Patients with Primary Antibody Deficiencies

Primary antibody deficiencies (PAD) represent a heterogeneous group of disorders, with common variable immunodeficiency being the most common with clinical significance. The main phenotypic defect resides in the inability of B cells to produce antibodies, and the cornerstone of therapy is immunoglobulin replacement treatment in order to fight infections. However, the management of the other inflammatory manifestations is inadequate, reinforcing the hypothesis that a complex genetic background affecting additional cell populations, such as polymorphonuclear cells (PMN) and monocytes, influences the expression of the clinical phenotype of the disease. In this study, we investigated by flow cytometry in different conditions (resting state, and after isolation and incubation, with and without stimuli) the expression pattern of several markers on PMN and monocytes, indicative of their maturation, capacity for chemotaxis, adhesion, opsonization, migration, and phagocytosis in 25 PAD patients, 12 healthy blood donors, and 4 septic patients. In this context, we also analyzed patients before and after the initiation of replacement treatment, as well as an untreated patient in different clinical conditions. Interestingly, we observed that PAD patients exhibit a chronic activation status of the innate immunity compartment, along with several differences in the expression of activation, maturation, and adhesion markers, with respect to different clinical conditions. Moreover, immunoglobulin replacement treatment had a favorable effect on PMN, as it was expressed by a more mature and less activated phenotype on basal state cells, and an enhanced activation capacity after LPS exposure. Thus, we conclude that PAD patients display a persistent innate immune cell activation, which is probably associated with the chronic inflammatory stress, usually observed in these disorders.

Diagnostic Approach to the Patients with Suspected Primary Immunodeficiency

BACKGROUND AND OBJECTIVE

Primary immunodeficiency diseases (PIDs) are a group of more than 350 disorders affecting distinct components of the innate and adaptive immune systems. In this review, the classic and advanced stepwise approach towards the diagnosis of PIDs are simplified and explained in detail.

RESULTS

Susceptibility to recurrent infections is the main hallmark of almost all PIDs. However, noninfectious complications attributable to immune dysregulation presenting with lymphoproliferative and/or autoimmune disorders are not uncommon. Moreover, PIDs could be associated with misleading presentations including allergic manifestations, enteropathies, and malignancies.

CONCLUSION

Timely diagnosis is the most essential element in improving outcome and reducing the morbidity and mortality in PIDs. This wouldn't be possible unless the physicians keep the diagnosis of PID in mind and be sufficiently aware of the approach to these patients.

A guide to cancer immunotherapy: from T cell basic science to clinical practice

The T lymphocyte, especially its capacity for antigen-directed cytotoxicity, has become a central focus for engaging the immune system in the fight against cancer. Basic science discoveries elucidating the molecular and cellular biology of the T cell have led to new strategies in this fight, including checkpoint blockade, adoptive cellular therapy and cancer vaccinology. This area of immunological research has been highly active for the past 50 years and is now enjoying unprecedented bench-to-bedside clinical success. Here, we provide a comprehensive historical and biological perspective regarding the advent and clinical implementation of cancer immunotherapeutics, with an emphasis on the fundamental importance of T lymphocyte regulation. We highlight clinical trials that demonstrate therapeutic efficacy and toxicities associated with each class of drug. Finally, we summarize emerging therapies and emphasize the yet to be elucidated questions and future promise within the field of cancer immunotherapy.

Intrahepatic TH17/TReg Cells in Homeostasis and Disease-It's All About the Balance

Both acute and chronic hepatic inflammation likely result from an imbalance in the T_H1/T_H2 cell response and can lead to liver fibrosis and end-stage liver disease. More recently, a novel CD4+ T helper cell subset was described, characterized by the production of IL-17 and IL-22. These T_H17 cells 50were predominantly implicated in host defense against infections and in autoimmune diseases. Interestingly, studies over the last 10 years revealed that the development of T_H17 cells favors pro-inflammatory responses in almost all tissues and there is a reciprocal relationship between T_H17 and T_Reg cells. The balance between T_H17and T_Reg cells is critical for immune reactions, especially in injured liver tissue and the return to immune homeostasis. The pathogenic contribution of T_H17 and T_Reg cells in autoimmunity, acute infection, and chronic liver injury is diverse and varies among disease etiologies. Understanding the mechanisms underlying T_H17 cell development, recruitment, and maintenance, along with the suppression of T_Reg cells, will inform the development of new therapeutic strategies in liver diseases. Active manipulation of the balance between pathogenic and regulatory processes in the liver may assist in the restoration of homeostasis, especially in hepatic inflammation.

Uncoupling Therapeutic Efficacy from Immune-Related Adverse Events in Immune Checkpoint Blockade

Immunotherapy with monoclonal antibodies targeting immune checkpoint molecules, including programmed death-1 (PD-1), PD ligand-1 (PD-L1), and cytotoxic T-lymphocyte-associated antigen (CTLA)-4, has become prominent in the treatment of many types of cancer. However, a significant number of patients treated with immune checkpoint inhibitors (ICIs) develop immune-related adverse events (irAEs). irAEs can affect any organ system, and although most are clinically manageable, irAEs can result in mortality or long-term morbidity. Factors that can predict irAEs remain elusive. Understanding the etiology of ICI-induced irAEs and ways to limit these adverse events are needed. In this review, we provide basic science and clinical insights on the mechanisms responsible for ICI efficacy and ICI-induced irAEs. We further provide insights into approaches that may uncouple irAEs from the ability of ICIs to kill tumor cells.

Early-onset autoimmunity associated with SOCS1 haploinsufficiency

Autoimmunity can occur when a checkpoint of self-tolerance fails. The study of familial autoimmune diseases can reveal pathophysiological mechanisms involved in more common autoimmune diseases. Here, by whole-exome/genome sequencing we identify heterozygous, autosomal-dominant, germline loss-of-function mutations in the SOCS1 gene in ten patients from five unrelated families with early onset autoimmune manifestations. The intracellular protein SOCS1 is known to downregulate cytokine signaling by inhibiting the JAK-STAT pathway. Accordingly, patient-derived lymphocytes exhibit increased STAT activation in vitro in response to interferon-γ, IL-2 and IL-4 that is reverted by the JAK1/JAK2 inhibitor ruxolitinib. This effect is associated with a series of in vitro and in vivo immune abnormalities consistent with lymphocyte hyperactivity. Hence, SOCS1 haploinsufficiency causes a dominantly inherited predisposition to early onset autoimmune diseases related to cytokine hypersensitivity of immune cells.

Regulating the regulators: Is introduction of an antigen-specific approach in regulatory T cells the next step to treat autoimmunity?

In autoimmunity, the important and fragile balance between immunity and tolerance is disturbed, resulting in abnormal immune responses to the body's own tissues and cells. CD4⁺CD25^hiFoxP3⁺ regulatory T cells (Tregs) induce peripheral tolerance in vivo by means of direct cell-cell contact and release of soluble factors, or indirectly through antigen-presenting cells (APC), thereby controlling auto-reactive effector T cells. Based on these unique capacities of Tregs, preclinical studies delivered proof-of-principle for the clinical use of Tregs for the treatment of autoimmune diseases. To date, the first clinical trials using ex vivo expanded polyclonal Tregs have been completed. These pioneering studies demonstrate the feasibility of generating large numbers of polyclonal Tregs in a good manufacturing practices (GMP)-compliant manner, and that infusion of Tregs is well tolerated by patients with no evidence of general immunosuppression. Nonetheless, only modest clinical results were observed, arguing that a more antigen-specific approach might be needed to foster a durable patient-specific clinical cell therapy without the risk for general immunosuppression. In this review, we discuss current knowledge, applications and future goals of adoptive immune-modulatory Treg therapy for the treatment of autoimmune disease and transplant rejection. We describe the key advances and prospects of the potential use of T cell receptor (TCR)- and chimeric antigen receptor (CAR)-engineered Tregs in future clinical applications. These approaches could deliver the long-awaited breakthrough in stopping undesired autoimmune responses and transplant rejections.

Understanding and Overcoming the Inflammatory Toxicities of Immunotherapy

Checkpoint blockade immunotherapy has led to impressive therapeutic responses in a wide variety of tumors, but also leads to a spectrum of inflammatory toxicities that can involve any organ system in the body. Although most inflammatory toxicities resolve with systemic immune suppression, fatal toxicities can occur, and interruption and discontinuation of immunotherapy because of toxicity are common. In addition to their clinical impact, these inflammatory toxicities also provide a window into immune regulation in humans. By studying the cellular and molecular mechanisms that drive this inflammation, we have an opportunity to learn how the immune checkpoints, cytotoxic T lymphocyte antigen-4 and programmed death-1 and its ligand, maintain immune homeostasis throughout the body. Although we have an increasingly detailed understanding of the mechanisms that drive effective antitumor immunity, we have a rudimentary picture of the mechanisms of toxicity. Most toxicities involve barrier organs, suggesting an important role for interactions with the environment, including the microbiome. Early analyses have implicated cytotoxic T cells, although the antigens recognized by these cells, and the pathways activated by and around them are still unknown. By gaining a detailed understanding of the immune mechanisms of toxicity, we have the potential to develop novel interventions for them. These treatments should take advantage of differences between effective antitumor immunity and the principal drivers of organ inflammation. By targeting these mechanistic differences, we can develop therapies that can be used alongside immunotherapy, blocking inflammatory toxicity while preserving or even enhancing the response to cancer.

Human inborn errors of immunity caused by defects of receptor and proteins of cellular membrane

Inborn errors of immunity are diseases of the immune system resulting from mutations that alter the expression of encoded proteins or molecules. Total updated number of these disorders is currently 406, with 430 different identified gene defects involved. Studies of the underlying mechanisms have contributed in better understanding the pathophysiology of the diseases, but also the complexity of the biology of innate and adaptive immune system and its interaction with microbes. In this review we present and briefly discuss Inborn Errors of Immunity caused by defects in genes encoding for receptors and protein of cellular membrane, including cytokine receptors, T cell antigen receptor (TCR) complex, cellular surface receptors or receptors signaling causing predominantly antibody deficiencies, co-stimulatory receptors and others. These alterations impact many biological processes of immune-system cells, including development, proliferation, activation and down-regulation of the immunological response, and result in a variety of diseases that present with distinct clinical features or with overlapping signs and symptoms.

Targeting co-stimulatory molecules in autoimmune disease

Therapeutic targeting of immune checkpoints has garnered significant attention in the area of cancer immunotherapy, in which efforts have focused in particular on cytotoxic T lymphocyte antigen 4 (CTLA4) and PD1, both of which are members of the CD28 family. In autoimmunity, these same pathways can be targeted to opposite effect: to curb the over-exuberant immune response. The CTLA4 checkpoint serves as an exemplar, whereby CTLA4 activity is blocked by antibodies in cancer immunotherapy and augmented by the provision of soluble CTLA4 in autoimmunity. Here, we review the targeting of co-stimulatory molecules in autoimmune diseases, focusing in particular on agents directed at members of the CD28 or tumour necrosis factor receptor families. We present the state of the art in co-stimulatory blockade approaches, including rational combinations of immune inhibitory agents, and discuss the future opportunities and challenges in this field.

Safety and efficacy of abatacept in patients with treatment-resistant SARCoidosis (ABASARC) - protocol for a multi-center, single-arm phase IIa trial

INTRODUCTION

Sarcoidosis is a granulomatous systemic disease that becomes chronic in approximately one third of affected patients resulting in quality of life and functional impairment. Immunosuppressive drugs other than steroids represent alternative therapeutic options, but side effects like liver and bone marrow toxicity or increased susceptibility to infections limit their use. Pathophysiological studies in sarcoidosis patients demonstrate altered regulatory T-cell functions with a reduced expression of CTLA-4 (CD152) and prolonged inflammation. Therefore, interfering with CTLA-4 using abatacept might be a therapeutic option in sarcoidosis similar to rheumatoid arthritis therapy.

METHODS/DESIGN

This is a multicenter prospective open-labeled single arm phase II study addressing the safety of abatacept in sarcoidosis patients. 30 patients with chronic sarcoidosis requiring immunosuppressive therapy beyond 5 mg prednisolone equivalent will be treated with abatacept in combination with corticosteroids for one year in two centers.The primary endpoint is the number and characterization of severe infectious complications under treatment with abatacept.Secondary endpoints are the rate of all infections, patient-related outcomes (assessed by questionnaires), lung function and immunological parameters including alveolar inflammation assessed by bronchoaveolar lavage.

DISCUSSION

This is the first trial of abatacept in patients with sarcoidosis. It is hypothesized that administration of abatacept is safe in patients with chronic sarcoidosis and can limit ongoing inflammation. Patients' wellbeing is assessed by established questionnaires. Immunological work-up will highlight the effect of abatacept on inflammatory pathways in sarcoidosis.

TRIAL REGISTRATION

The trial has been registered at the German Clinical Trial Registry (Deutsches Register Klinischer Studien, DRKS) with the identity number DRKS00011660.

Comprehensive Targeted Sequencing Identifies Monogenic Disorders in Patients With Early-onset Refractory Diarrhea

OBJECTIVES

Causes of early-onset refractory diarrhea include exudative diarrhea associated with very early-onset inflammatory bowel diseases, osmotic or secretory diarrhea, and protein-losing enteropathy. Monogenic disorders are included in these diseases, yet a comprehensive genetic analysis has not been fully established.

METHODS

We established targeted gene panels covering all responsible genes for early-onset diarrhea. In total, 108 patients from 15 institutions were enrolled in this study. We collected clinical data from all patients. Seventy-three patients with exudative diarrhea, 4 with osmotic or secretory diarrhea and 8 with protein-losing enteropathy were subjected to genetic analysis.

RESULTS

A total of 15 out of the 108 enrolled patients (13.9%) were identified as monogenic. We identified 1 patient with RELA, 2 with TNFAIP3, 1 with CTLA4, 1 with SLCO2A1, 4 with XIAP, 3 with IL10RA, 1 with HPS1, 1 with FOXP3, and 1 with CYBB gene mutations. We also identified 1 patient with NFKB2 and 1 with TERT mutations from the gene panel for primary immunodeficiency syndromes. The patient with refractory diarrhea caused by heterozygous truncated RelA protein expression is the first case identified worldwide, and functional analysis revealed that the mutation affected nuclear factor kappa B signaling. Genotypes were significantly associated with the clinical and pathological findings in each patient.

CONCLUSIONS

We identified variable monogenic diseases in the patients and found that genes responsible for primary immunodeficiency diseases were frequently involved in molecular pathogenesis. Comprehensive genetic analysis was useful for accurate molecular diagnosis, understanding of underlying pathogenesis, and selecting the optimal treatment for patients with early-onset refractory diarrhea.An infographic for this article is available at: http://links.lww.com/MPG/B853.

Tissue regulatory T cells

Foxp3+  CD4+ regulatory T cells (Tregs) are an immune cell lineage endowed with immunosuppressive functionality in a wide array of contexts, including both anti-pathogenic and anti-self responses. In the past decades, our understanding of the functional diversity of circulating or lymphoid Tregs has grown exponentially. Only recently, the importance of Tregs residing within non-lymphoid tissues, such as visceral adipose tissue, muscle, skin and intestine, has been recognized. Not only are Tregs critical for influencing the kinetics and strength of immune responses, but the regulation of non-immune or parenchymal cells, also fall within the purview of tissue-resident or infiltrating Tregs. This review focuses on providing a systematic and comprehensive comparison of the molecular maintenance, local adaptation and functional specializations of Treg populations operating within different tissues.

Multinational Association of Supportive Care in Cancer (MASCC) 2020 clinical practice recommendations for the management of severe gastrointestinal and hepatic toxicities from checkpoint inhibitors

Immune-related adverse events (IrAEs) affecting the gastrointestinal (GI) tract and liver are among the most frequent and most severe inflammatory toxicities from contemporary immunotherapy. Inflammation of the colon and or small intestines (entero)colitis is the single most common GI IrAE and is an important cause of delay of discontinuation of immunotherapy. The severity of these GI IrAEs can range from manageable with symptomatic treatment alone to life-threatening complications, including perforation and liver failure. The frequency and severity of GI IrAEs is dependent on the specific immunotherapy given, with cytotoxic T lymphocyte antigen (CTLA)-4 blockade more likely to induce severe GI IrAEs than blockade of either programmed cell death protein 1 (PD-1) or PD-1 ligand (PD-L1), and combination therapy showing the highest rate of GI IrAEs, particularly in the liver. To date, we have minimal prospective data on the appropriate diagnosis and management of GI IrAEs, and recommendations are based largely on retrospective data and expert opinion. Although clinical diagnoses of GI IrAEs are common, biopsy is the gold standard for diagnosis of both immunotherapy-induced enterocolitis and hepatitis and can play an important role in excluding competing, though less common, diagnoses and ensuring optimal management. GI IrAEs typically respond to high-dose corticosteroids, though a significant fraction of patients requires secondary immune suppression. For colitis, both TNF-α blockade with infliximab and integrin inhibition with vedolizumab have proved highly effective in corticosteroid-refractory cases. Detailed guidelines have been published for the management of low-grade GI IrAEs. In the setting of more severe toxicities, involvement of a GI specialist is generally recommended. The purpose of this review is to survey the available literature and provide management recommendations focused on the GI specialist.

B Cell Disorders in Children: Part II

PURPOSE OF REVIEW

B cell disorders result in decreased levels or function of immunoglobulins in an individual. Genetic mutations have been reported in a variety of B cell disorders. This review, in follow-up to a previous review, describes some rare B cell disorders as well as their known underlying genetic etiologies.

RECENT FINDINGS

Genetic studies identify and permit precise classification of an increasing number of B cell disorders, leading to a greater understanding of B cell development and function. The B cell disorders are rare diseases. While clinicians are most familiar with X-linked agammaglobulinemia and so-called common variable immunodeficiency (CVID), there are many causes of hypogammaglobulinemia. Genetic testing provides a specific diagnosis, offers useful information for genetic counseling, and can identify previously unrecognized B cell disorders.

COVID-19 and immunological regulations - from basic and translational aspects to clinical implications

The COVID‐19 pandemic caused by SARS‐CoV‐2 has far‐reaching direct and indirect medical consequences. These include both the course and treatment of diseases. It is becoming increasingly clear that infections with SARS‐CoV‐2 can cause considerable immunological alterations, which particularly also affect pathogenetically and/or therapeutically relevant factors.

Against this background we summarize here the current state of knowledge on the interaction of SARS‐CoV‐2/COVID‐19 with mediators of the acute phase of inflammation (TNF, IL‐1, IL‐6), type 1 and type 17 immune responses (IL‐12, IL‐23, IL‐17, IL‐36), type 2 immune reactions (IL‐4, IL‐13, IL‐5, IL‐31, IgE), B‐cell immunity, checkpoint regulators (PD‐1, PD‐L1, CTLA4), and orally druggable signaling pathways (JAK, PDE4, calcineurin). In addition, we discuss in this context non‐specific immune modulation by glucocorticosteroids, methotrexate, antimalarial drugs, azathioprine, dapsone, mycophenolate mofetil and fumaric acid esters, as well as neutrophil granulocyte‐mediated innate immune mechanisms.

From these recent findings we derive possible implications for the therapeutic modulation of said immunological mechanisms in connection with SARS‐CoV‐2/COVID‐19. Although, of course, the greatest care should be taken with patients with immunologically mediated diseases or immunomodulating therapies, it appears that many treatments can also be carried out during the COVID‐19 pandemic; some even appear to alleviate COVID‐19.

Rheumatologic and autoimmune manifestations in primary immune deficiency

PURPOSE OF REVIEW

Here we review the rheumatologic and autoimmune features of primary immune deficiencies with a focus on recently recognized genetic diseases, the spectrum of autoimmunity in PID, and targeted therapies.

RECENT FINDINGS

Primary immune deficiencies (PIDs) were initially described as genetic diseases of the immune system leading to susceptibility to infection. It is now well recognized that immune dysfunction and dysregulation also cause noninfectious complications including autoimmunity. The increased application of molecular testing for PID has revealed the diversity of clinical disease. Recent discoveries of diseases with prominent autoimmunity include activated phosphoinositide 3-kinase δ syndrome and PIDs caused by gain-of-function in STAT1 and STAT3. Similarly, identification of larger cohorts of patients with molecular diagnoses in more common PIDs, such as common variable immune deficiency (CVID), has led to increased understanding of the range of autoimmunity in PIDs. Understanding the molecular basis of these PIDs has the potential to lead to targeted therapy to treat associated autoimmunity.

SUMMARY

Autoimmunity and rheumatologic disease can be presenting symptoms and/or complicating features of primary immunodeficiencies. Evaluation for PIDs in patients who have early-onset, multiple, and/or atypical autoimmunity can enhance diagnosis and therapeutic options.

Targeted pharmacologic immunomodulation for inborn errors of immunity

Inborn errors of immunity consist of over 400 known single gene disorders that may manifest with infection susceptibility, autoimmunity, autoinflammation, hypersensitivity and cancer predisposition. Most patients are treated symptomatically with immunoglobulin replacement, prophylactic antimicrobials or broad immunosuppression pertaining to their disease phenotype. Other than haematopoietic stem cell transplantation, the aforementioned treatments do little to alter disease morbidity or mortality. Further, many patients may not be transplant candidates. In this review, we describe monogenic disorders affecting leucocyte migration, disorders of immune synapse formation and dysregulation of immune cell signal transduction. We highlight the use of off-label small molecules and biologics mechanistically targeted to altered disease pathophysiology of such diseases.

COVID‐19 und Immunregulation – von grundlegenden und translationalen Aspekten zu klinischen Implikationen

Die durch SARS‐CoV‐2 verursachte Pandemie COVID‐19 hat weitreichende direkte und indirekte medizinische Folgen. Dazu gehören sowohl der Verlauf als auch die Behandlung vieler Krankheiten. Es wird immer deutlicher, dass Infektionen mit SARS‐CoV‐2 erhebliche immunologische Veränderungen verursachen können, die insbesondere auch pathogenetisch und/oder therapeutisch relevante Faktoren betreffen.

Vor diesem Hintergrund fassen wir hier den aktuellen Wissensstand zur Interaktion von SARS‐CoV‐2/COVID‐19 mit Mediatoren der akuten Phase der Entzündung (TNF, IL‐1, IL‐6), der Typ‐1‐ und Typ‐17‐Immunantwort (IL‐12, IL‐23, IL‐17, IL‐36), Typ‐2‐Immunreaktionen (IL‐4, IL‐13, IL‐5, IL‐31, IgE), B‐Zell‐Immunität, Checkpoint‐Regulatoren (PD‐1, PD‐L1, CTLA4) und Signalwegen, die durch oral applizierte Medikamente moduliert werden (JAK, PDE4, Calcineurin), zusammen. Darüber hinaus diskutieren wir in diesem Zusammenhang die unspezifische Immunmodulation durch Glukokortikosteroide, Methotrexat, Malariamittel, Azathioprin, Dapson, Mycophenolsäure‐Derivate und Fumarsäureester sowie angeborene Immunmechanismen neutrophiler Granulozyten.

Aus diesen neueren Erkenntnissen leiten wir mögliche Implikationen für die therapeutische Modulation der genannten immunologischen Mechanismen im Zusammenhang mit SARS‐CoV‐2/COVID‐19 ab. Obwohl natürlich bei Patienten mit immunologisch vermittelten Krankheiten oder immunmodulierenden Therapien größte Vorsicht geboten ist, scheint es, dass viele Behandlungen auch während der COVID‐19‐Pandemie durchgeführt werden können; einige scheinen COVID‐19 sogar zu lindern.

Rituximab and antimetabolite treatment of granulomatous and lymphocytic interstitial lung disease in common variable immunodeficiency

BACKGROUND

Granulomatous and lymphocytic interstitial lung disease (GLILD) is a life-threatening complication in patients with common variable immunodeficiency (CVID), but the optimal treatment is unknown.

OBJECTIVE

Our aim was to determine whether rituximab with azathioprine or mycophenolate mofetil improves the high-resolution computed tomography (HRCT) chest scans and/or pulmonary function test results in patients with CVID and GLILD.

METHODS

A retrospective chart review of clinical and laboratory data on 39 patients with CVID and GLILD who completed immunosuppressive therapy was performed. Chest HRCT scans, performed before therapy and after the conclusion of therapy, were blinded, randomized, and scored independently by 2 radiologists. Differences between pretreatment and posttreatment HRCT scan scores, pulmonary function test results, and lymphocyte subsets were analyzed. Whole exome sequencing was performed on all patients.

RESULTS

Immunosuppressive therapy improved patients' HRCT scan scores (P < .0001), forced vital capacity (P = .0017), FEV₁ (P = .037), and total lung capacity (P = .013) but not their lung carbon monoxide diffusion capacity (P = .12). Nine patients relapsed and 6 completed retreatment, with 5 of 6 of these patients (83%) having improved HRCT scan scores (P = .063). Relapse was associated with an increased number of B cells (P = .016) and activated CD4 T cells (P = .016). Four patients (10%) had pneumonia while undergoing active treatment, and 2 patients (5%) died after completion of therapy. Eight patients (21%) had a damaging mutation in a gene known to predispose (TNFRSF13B [n = 3]) or cause a CVID-like primary immunodeficiency (CTLA4 [n = 2], KMT2D [n = 2], or BIRC4 [n = 1]). Immunosuppression improved the HRCT scan scores in patients with (P = .0078) and without (P < .0001) a damaging mutation.

CONCLUSIONS

Immunosuppressive therapy improved the radiographic abnormalities and pulmonary function of patients with GLILD. A majority of patients had sustained remissions.

Inflammatory Manifestations of Systemic Diseases in the Central Nervous System

PURPOSE OF REVIEW

This review presents the current recommended therapeutic interventions for inflammatory disease in the central nervous system (CNS) secondary to systemic diseases of immune dysregulation. Treatment recommendations for CNS inflammation associated with rheumatologic conditions, immune-related adverse effects from immune checkpoint inhibitors (ICIs), and demyelinating disease from tumor necrosis factor-α (anti-TNFs) are explored. Additional therapeutic options for inflammation related to postviral syndromes and genetic immunodeficiencies are also discussed.

RECENT FINDINGS

In addition to treatment of mild, moderate, and severe CNS rheumatologic disease as guided by the European League Against Rheumatism (EULAR), early consideration of rituximab for severe IgG4-related disease and induction with anti-TNF therapy for severe neurosarcoidosis should be considered. Although often not first line, treatment options for CNS inflammatory diseases based on disease mechanism are emerging, including tocilizumab for Behcet's disease, natalizumab for ICI associated autoimmune encephalitis, and abatacept for treatment of infiltrative disease secondary to CTLA-4 deficiency. Hematopoietic stem cell treatments represent highly efficacious but risky options for autoimmunity related to genetic immunodeficiency.

SUMMARY

While early high dose steroids remains first line therapy for most CNS inflammatory conditions, a rapidly expanding arsenal of immune targeted therapies offers clinicians tailored disease specific options for treatment.

Mechanisms of Immune-Related Complications in Cancer Patients Treated with Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) have changed the prognosis of many cancer patients. Blocking antibodies targeting inhibitory cytotoxic T-lymphocyte-associated antigen 4 or programmed cell death protein-1 receptors or the programmed cell death ligand-1 have led to long-lasting remissions in patients with even advanced cancers. Main side effects induced by ICIs are inflammatory complications with sometimes severe sequelae for patients. Recent studies have improved our understanding how such immune-related adverse events (irAEs) develop. Here, we summarize the current knowledge of pathomechanisms involved in the de-velopment of irAEs with a particular focus on potential pathways that could be targeted to prevent severe immune-related complications in patients treated with cancer immunotherapy.

Human inborn errors of immunity: An expanding universe

Molecular, cellular, and clinical studies of human inborn errors of immunity have revolutionized our understanding of their pathogenesis, considerably broadened their spectrum of immunological and clinical phenotypes, and enabled successful targeted therapeutic interventions. These studies have also been of great scientific merit, challenging a number of immunological notions initially established in inbred mice while revealing previously unrecognized mechanisms of host defense by leukocytes and other cells and of both innate and adaptive tolerance to self.

Two sides of the same medal: Noncoding mutations reveal new pathological mechanisms and insights into the regulation of gene expression

Noncoding sequences constitute the major part of the human genome and also of pre-mRNAs. Single nucleotide variants in these regions are often overlooked, but may be responsible for much of the variation of phenotypes observed. Mutations in the noncoding part of pre-mRNAs often reveal new and meaningful insights into the regulation of cellular gene expression. Thus, the mechanistic analysis of the pathological mechanism of such mutations will both foster a deeper understanding of the disease and the underlying cellular pathways. Even synonymous mutations can cause diseases, since the primary mRNA sequence not only encodes amino acids, but also encrypts information on RNA-binding proteins and secondary structure. In fact, the RNA sequence directs assembly of a specific mRNP complex, which in turn dictates the fate of the mRNA or regulates its biogenesis. The accumulation of genomic sequence information is increasing at a rapid pace. However, much of the diversity uncovered may not explain the phenotype of a certain syndrome or disease. For this reason, we also emphasize the value of mechanistic studies on pathological mechanisms being complementary to genome-wide studies and bioinformatic approaches. This article is categorized under: RNA Processing > Splicing Regulation/Alternative Splicing RNA Processing > 3' End Processing RNA in Disease and Development > RNA in Disease.

Harnessing NK Cell Checkpoint-Modulating Immunotherapies

During the host immune response, the precise balance of the immune system, regulated by immune checkpoint, is required to avoid infection and cancer. These immune checkpoints are the mainstream regulator of the immune response and are crucial for self-tolerance. During the last decade, various new immune checkpoint molecules have been studied, providing an attractive path to evaluate their potential role as targets for effective therapeutic interventions. Checkpoint inhibitors have mainly been explored in T cells until now, but natural killer (NK) cells are a newly emerging target for the determination of checkpoint molecules. Simultaneously, an increasing number of therapeutic dimensions have been explored, including modulatory and inhibitory checkpoint molecules, either causing dysfunction or promoting effector functions. Furthermore, the combination of the immune checkpoint with other NK cell-based therapeutic strategies could also strengthen its efficacy as an antitumor therapy. In this review, we have undertaken a comprehensive review of the literature to date regarding underlying mechanisms of modulatory and inhibitory checkpoint molecules.

Aplastic anaemia: Current concepts in diagnosis and management

Aplastic anaemia is a rare, previously fatal condition with a significantly improved survival rate owing to advances in understanding of the pathophysiology and improved treatment strategies including haematopoietic stem cell transplantation. Although a rare condition, aplastic anaemia continues to present a high burden for affected patients, their families and the health system due to the prolonged course of disease often associated with high morbidity and the uncertainty regarding clinical outcome. Modern molecular and genetic techniques including next-generation sequencing have contributed to a better understanding of this heterogeneous group of conditions, albeit at a cost of increased complexity of clinical decision-making regarding prognosis and choice of treatment for individual patients. Here we present a concise and comprehensive review of aplastic anaemia and closely related conditions based on extensive literature review and long-standing clinical experience. The review takes the reader across the complex pathophysiology consisting of three main causative mechanisms of bone marrow destruction resulting in aplastic anaemia: direct injury, immune mediated and bone marrow failure related including inherited and clonal disorders. A comprehensive diagnostic algorithm is presented and an up-to-date therapeutic approach to acquired immune aplastic anaemia, the most represented type of aplastic anaemia, is described. Overall, the aim of the review is to provide paediatricians with an update of this rare, heterogeneous and continuously evolving condition.

Molecular Pathways of Colon Inflammation Induced by Cancer Immunotherapy

Checkpoint blockade with antibodies specific for the PD-1 and CTLA-4 inhibitory receptors can induce durable responses in a wide range of human cancers. However, the immunological mechanisms responsible for severe inflammatory side effects remain poorly understood. Here we report a comprehensive single-cell analysis of immune cell populations in colitis, a common and severe side effect of checkpoint blockade. We observed a striking accumulation of CD8 T cells with highly cytotoxic and proliferative states and no evidence of regulatory T cell depletion. T cell receptor (TCR) sequence analysis demonstrated that a substantial fraction of colitis-associated CD8 T cells originated from tissue-resident populations, explaining the frequently early onset of colitis symptoms following treatment initiation. Our analysis also identified cytokines, chemokines, and surface receptors that could serve as therapeutic targets for colitis and potentially other inflammatory side effects of checkpoint blockade.

Immune Checkpoint Inhibitor-Mediated Diarrhea and Colitis: A Clinical Review

Immune-mediated diarrhea and colitis (IMDC) is among the most common immune-related adverse events in patients with cancer treated with immune checkpoint inhibitors (ICIs). Many factors will affect the risk of IMDC, including the type of ICI used, the type of underlying cancer, and patient characteristics. A recent study showed that preexisting inflammatory bowel disease significantly increases the risk of diarrhea and colitis with ICI treatment. In terms of management, early endoscopic evaluation improves clinical outcome by identifying high-risk patients who will benefit from early add-on immunosuppressants. Inflammatory markers, including fecal lactoferrin and calprotectin, are good screening tools to predict which patients are at risk for colitis. Calprotectin especially is associated with colitis outcome and can be used as a surrogate marker to follow treatment response. Corticosteroids remain the first-line medical treatment of IMDC management, and add-on therapy with vedolizumab or infliximab should be considered in selected patients. Fecal microbiota transplantation may be considered in refractory cases. The decision to resume ICI should be decided by balancing the risk of recurrent IMDC and the likelihood of benefiting from further ICI treatment. There is no clear evidence about whether the use of immunosuppressants will result in a worse cancer outcome. With emerging evidence, our understanding and management strategies are likely to evolve in the future.

Lower T Regulatory and Th17 Cell Populations Predicted by RT-PCR-Amplified FOXP3 and RORγt Genes Are Not Rare in Patients With Primary Immunodeficiency Diseases

Deficiencies in T regulatory (Treg) and Th17 cells attenuate peripheral tolerance and the IL-17 family of cytokines, contributing to autoimmune disorders and opportunistic (fungal) infections, respectively. Because of limited blood samples from patients with primary immunodeficiency diseases (PIDs), a positive correlation/linear relationship between Treg and Th17 cells and their respective expressions of transcription factors forkhead box P3 (FOXP3) and retinoic acid-related orphan receptor γ (RORγt) by real-time PCR (RT-PCR) amplification, was used to predict the percentages of Treg and Th17 cells in peripheral blood. Compared to glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression, the percentages of Treg and Th17 cells were calculated as the linear relationship to the 2^−ΔCT value (cycle threshold). Among 91 PIDs patients, 68 and 78 had predicted Treg and Th17 percentages below 5% of the normal ranges (0.859 and 0.734%, respectively), which expanded different categories beyond obvious T cell deficiency. Notably, FOXP3 was undetectable in one patient (CVID), RORγt was undetectable in six patients (one CVID, one CID, two neutropenia, one WAS, and one CMC), and both were undetectable in four patients (two SCID, one STAT1, and one periodic fever). In contrast, two patients with auto-IFNγ antibodies had increased susceptibility to intracellular mycobacterial infections, interrupted Th1 development and subsequent elevation in the Th17 cells. Both predicted Treg and Th17 percentages in the PIDs patients were more independent of age (months) than in the controls. The predicted Th17/Treg ratio in the PIDs patients, overall, was lower than that in the healthy controls (0.79 ± 0.075 vs. 1.16 ± 0.208; p = 0.038). In conclusion, lower predicted Treg and Th17 cell populations calculated by RT-PCR-amplified FOXP3 and RORγt in PIDs patients at diagnosis can explain the higher potential phenotypes of autoimmune disorders and opportunistic infections, although effective interventions in the early stage might have prevented such phenotypic development and caused a statistical bias in the comparisons.

Single Nucleotide Polymorphisms in PPARD Associated with Systemic Lupus Erythematosus in Chinese Populations

Background

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease characterized by apoptotic clearance deficiency provoking autoimmune responses and leading to multiple organ damage. PPAR-δ, encoded by the PPARD gene, was induced in macrophages promoting the timely disposal of apoptotic cells. Biological studies had provided solid foundation of PPARD involvement in SLE; it is worthwhile to further explore the genetic contribution of PPARD to SLE.

Methods

We performed a discovery-replication genetic association study. The discovery study was based on previous reported GWAS data. And the replication study was conducted in 1003 SLE patients and 815 healthy controls from Henan, Middle East of China. Further, we analyzed the eQTL effect to identify possible functional significance.

Results

In the genetic association analysis, we observed significant association between the risk C allele of rs4713853 (p = 0.03, OR 1.167, 95% CI 1.015-1.341) and increased SLE susceptibility. Moreover, individuals with the risk C allele were associated with lower expression of PPARD and DEF6. Our clinical analysis showed that SLE patients with the risk C allele of rs4713853 were more likely to present a higher proportion of anti-Sm antibody presence (CC+CT vs. TT, 20.0% vs. 14.2%, p = 0.039) and higher level of Scr (median inter quarter range CC+CT vs. TT, 56 48-71 vs. 54 46-64 μmol/L, p = 0.002).

Conclusions

In conclusion, our study identified a novel association between PPARD rs4713853 and SLE susceptibility in Chinese populations. By integrating multiple layers of analysis, we suggested that PPARD might be a main candidate in the pathogenesis of SLE.

Chronic Lung Disease in Primary Antibody Deficiency: Diagnosis and Management

Chronic lung disease is a complication of primary antibody deficiency (PAD) associated with significant morbidity and mortality. Manifestations of lung disease in PAD are numerous. Thoughtful application of diagnostic approaches is imperative to accurately identify the form of disease. Much of the treatment used is adapted from immunocompetent populations. Recent genomic and translational medicine advances have led to specific treatments. As chronic lung disease has continued to affect patients with PAD, we hope that continued advancements in our understanding of pulmonary pathology will ultimately lead to effective methods that alleviate impact on quality of life and survival.

Two neurologic facets of CTLA4-related haploinsufficiency

Objective

To describe the clinical and radiologic neurologic characteristics of patients with cytotoxic T-lymphocyte antigen-4 (CTLA4) haploinsufficiency.

Methods

Three patients from 2 families had neurologic manifestations in the context of CTLA4 haploinsufficiency. Their clinical and MRI findings are presented.

Results

A 16-year-old boy with a previous diagnosis of combined immunodeficiency presented with severe recurrent episodes of headaches, motor deficit, and seizures associated with waxing and waning gadolinium-enhancing FLAIR cortical/juxtacortical hyperintensities. His sister, who also had combined immunodeficiency, had a brain MRI when she was aged 13 years due to recent headaches and transient right hemianopsia. It revealed a gadolinium-enhancing left occipital white matter hyperintensity. Another 49-year-old woman had progressive visual loss and cerebellar ataxia in the context of recurrent pulmonary infections. All 3 patients were found to have inherited CTLA4 haploinsufficiency. Patient 1's general condition and neurologic manifestations were completely controlled with abatacept (CTLA4-Ig).

Conclusions

These cases suggest that in addition to the variable clinical penetrance and wide spectrum of CTLA4 haploinsufficiency, its neurologic spectrum is broad, ranging from recurrent tumefactive lesions to progressive deficits including cerebellar ataxia and optic atrophy with leukoencephalopathy. These phenotypes must be recognized, and should lead to a complete immunologic workup, because potentially effective targeted immunotherapy exists.

Transcriptional and epigenetic basis of Treg cell development and function: its genetic anomalies or variations in autoimmune diseases

Naturally arising regulatory CD4+ T (Treg) cells, which specifically express the transcription factor FoxP3 in the nucleus and CD25 and CTLA-4 on the cell surface, are a T-cell subpopulation specialized for immune suppression, playing a key role in maintaining immunological self-tolerance and homeostasis. FoxP3 is required for Treg function, especially for its suppressive activity. However, FoxP3 expression per se is not necessary for Treg cell lineage commitment in the thymus and insufficient for full Treg-type gene expression in mature Treg cells. It is Treg-specific epigenetic changes such as CpG demethylation and histone modification that can confer a stable and heritable pattern of Treg type gene expression on developing Treg cells in a FoxP3-independent manner. Anomalies in the formation of Treg-specific epigenome, in particular, Treg-specific super-enhancers, which largely include Treg-specific DNA demethylated regions, are indeed able to cause autoimmune diseases in rodents. Furthermore, in humans, single nucleotide polymorphisms in Treg-specific DNA demethylated regions associated with Treg signature genes, such as IL2RA (CD25) and CTLA4, can affect the development and function of naïve Treg cells rather than effector T cells. Such genetic variations are therefore causative of polygenic common autoimmune diseases including type 1 diabetes and rheumatoid arthritis via affecting endogenous natural Treg cells. These findings on the transcription factor network with FoxP3 at a key position as well as Treg-specific epigenetic landscape facilitate our understanding of Treg cell development and function, and can be exploited to prepare functionally stable FoxP3-expressing Treg cells from antigen-specific conventional T cells to treat autoimmune diseases.

Incomplete penetrance in primary immunodeficiency: a skeleton in the closet

Primary immunodeficiencies (PIDs) comprise a diverse group of over 400 genetic disorders that result in clinically apparent immune dysfunction. Although PIDs are classically considered as Mendelian disorders with complete penetrance, we now understand that absent or partial clinical disease is often noted in individuals harboring disease-causing genotypes. Despite the frequency of incomplete penetrance in PID, no conceptual framework exists to categorize and explain these occurrences. Here, by reviewing decades of reports on incomplete penetrance in PID we identify four recurrent themes of incomplete penetrance, namely genotype quality, (epi)genetic modification, environmental influence, and mosaicism. For each of these principles, we review what is known, underscore what remains unknown, and propose future experimental approaches to fill the gaps in our understanding. Although the content herein relates specifically to inborn errors of immunity, the concepts are generalizable across genetic diseases.

Efficacy and Toxicity of Immune -Checkpoint Inhibitors in Patients With Preexisting Autoimmune Disorders

Immunotherapy is an important armamentarium for cancer treatment nowadays. Apart from their significant effectiveness in controlling disease they also generate potential severe immune related adverse effects. Preexistence of immune related conditions may eventually predispose to the development of more severe complication and extreme caution have been taken in treating these patients. We performed a literature review searching for case reports and case series in order to offer evidence-based data for clinical management of these patients. Preexisting serological-only immune abnormalities or presence of a predisposing genetic background does not seem to confer significant risk but existing data is scarce. Most patients with preexistent autoimmune diseases can probably treated with checkpoint inhibitors as they seem to have at least the same response rate as the general cancer population. Under treatment, a significant part of them (at least 30%) can experience a flare of their baseline disease which can sometime be severe. Life-threatening cases seems rare and disease flare can be generally managed with steroids. The volume of available data is more important for rheumatologic diseases than for inflammatory bowel diseases were more caution should be observed. However, it has to be kept in mind that new immune related adverse effects (IrAE) are seen with a similar frequency as the flare of the baseline disease. Both flare-up's and newly developed IrAE are generally manageable with a careful clinical follow-up and prompt therapy.

Multiple Sclerosis: Lipids, Lymphocytes, and Vitamin D

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. We review the two core MS features, myelin instability, fragmentation, and remyelination failure, and dominance of pathogenic CD4+ Th17 cells over protective CD4+ Treg cells. To better understand myelin pathology, we describe myelin biosynthesis, structure, and function, then highlight stearoyl-CoA desaturase (SCD) in nervonic acid biosynthesis and nervonic acid's contribution to myelin stability. Noting that vitamin D deficiency decreases SCD in the periphery, we propose it also decreases SCD in oligodendrocytes, disrupting the nervonic acid supply and causing myelin instability and fragmentation. To better understand the distorted Th17/Treg cell balance, we summarize Th17 cell contributions to MS pathogenesis, then highlight how 1,25-dihydroxyvitamin D3 signaling from microglia to CD4+ T cells restores Treg cell dominance. This signaling rapidly increases flux through the methionine cycle, removing homocysteine, replenishing S-adenosyl-methionine, and improving epigenetic marking. Noting that DNA hypomethylation and inappropriate DRB1*1501 expression were observed in MS patient CD4+ T cells, we propose that vitamin D deficiency thwarts epigenetic downregulation of DRB1*1501 and Th17 cell signature genes, and upregulation of Treg cell signature genes, causing dysregulation within the CD4+ T cell compartment. We explain how obesity reduces vitamin D status, and how estrogen and vitamin D collaborate to promote Treg cell dominance in females. Finally, we discuss the implications of this new knowledge concerning myelin and the Th17/Treg cell balance, and advocate for efforts to address the global epidemics of obesity and vitamin D deficiency in the expectation of reducing the impact of MS.

Regulatory T-cell therapy in Crohn's disease: challenges and advances

The prevalence of IBD is rising in the Western world. Despite an increasing repertoire of therapeutic targets, a significant proportion of patients suffer chronic morbidity. Studies in mice and humans have highlighted the critical role of regulatory T cells in immune homeostasis, with defects in number and suppressive function of regulatory T cells seen in patients with Crohn's disease. We review the function of regulatory T cells and the pathways by which they exert immune tolerance in the intestinal mucosa. We explore the principles and challenges of manufacturing a cell therapy, and discuss clinical trial evidence to date for their safety and efficacy in human disease, with particular focus on the development of a regulatory T-cell therapy for Crohn's disease.

Endocrine adverse events related with immune checkpoint inhibitors: an update for clinicians

Designated as scientific breakthrough of current decade, immune checkpoint inhibitors attenuate the cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and the programmed cell death 1 (PD-1)/ligand 1 (PD-L1) pathways, depriving cancer cells of a key strategy of evasion from immunosurveillance. The reinvigoration of immune response translates into clinical success, inevitably entwined with a novel constellation of immune-related adverse events. The present review dissects the endocrine immune-related adverse events, emphasizing their unique profile featured by unpredictable onset, irreversibility, nonspecific symptoms, wide clinical spectrum and sophisticated diagnostic work-up. Guidelines advocate individualized decision-making process guided by clinicians' judgement. Future perspective should be governed by five principles - prevention, anticipation, detection, treatment, monitoring - aiming to gain the optimal profit diminishing immunotoxicity.

Modulation of regulatory T cell function and stability by co-inhibitory receptors

Regulatory T (T_reg) cells constitute a dynamic population that is essential for controlling immune responses in health and disease. Defects in T_reg cell function and decreases in T_reg cell numbers have been observed in patients with autoimmunity and the opposite effects on T_reg cells occur in cancer settings. Current research on new therapies for these diseases is focused on modulating T_reg cell function to increase or decrease suppressive activity in autoimmunity and cancer, respectively. In this regard, several co-inhibitory receptors that are preferentially expressed by T_reg cells under homeostatic conditions have recently been shown to control T_reg cell function and stability in different disease settings. These receptors could be amenable to therapeutic targeting aimed at modulating T_reg cell function and plasticity. This Review summarizes recent data regarding the role of co-inhibitory molecules in the control of T_reg cell function and stability, with a focus on their roles and potential therapeutic use in autoimmunity and cancer.

Mechanisms of immune-related adverse events during the treatment of cancer with immune checkpoint inhibitors

Immune checkpoint inhibitors are novel biologic agents to treat cancer by inhibiting the regulatory interactions that limit T cell cytotoxicity to tumours. Current agents target either CTLA-4 or the PD-1/PD-L1 axis. Because checkpoints may also regulate autoreactivity, immune checkpoint inhibitor therapy is complicated by side effects known as immune-related adverse events (irAEs). The aim of this article is to review the mechanisms of these events. irAEs can involve different tissues and include arthritis and other rheumatic manifestations. The frequency of irAEs is related to the checkpoint inhibited, with the combination of agents more toxic. Because of their severity, irAEs can limit therapy and require immunosuppressive treatment. The mechanisms leading to irAEs are likely similar to those promoting anti-tumour responses and involve expansion of the T cell repertoire; furthermore, immune checkpoint inhibitors can affect B cell responses and induce autoantibody production. Better understanding of the mechanisms of irAEs will be important to improve patient outcome as well as quality of life during treatment.