Signal transducer and activator of transcription gain-of-function primary immunodeficiency/immunodysregulation disorders

Signal Transducer and Activator of Transcription Proteins at the Nexus of Immunodeficiency, Autoimmunity and Cancer

The signal transducer and activator of transcription (STAT) family of proteins has been demonstrated to perform pivotal roles downstream of a myriad of cytokines, particularly those that control immune cell production and function. This is highlighted by both gain-of-function (GOF) and loss-of-function (LOF) mutations being implicated in various diseases impacting cells of the immune system. These mutations are typically inherited, although somatic GOF mutations are commonly observed in certain immune cell malignancies. This review details the growing appreciation of STAT proteins as a key node linking immunodeficiency, autoimmunity and cancer.

Rabeprazole destroyed gastric epithelial barrier function through FOXF1/STAT3-mediated ZO-1 expression

Rabeprazole is a representative of proton pump inhibitors and widely used in anti-ulcer treatment. However, the effect of Rabeprazole on gut barrier function remains to be identified. In this study, we show that ZO-1 expression is decreased in patients receiving Rabeprazole by immunofluorescence (IF) analysis. Western blotting (WB) and real-time PCR (qPCR) results demonstrate that Rabeprazole treatment leads to a significant downregulation of ZO-1 expression through inhibition of the FOXF1/STAT3 pathway, leading to destroy barrier function, which illustrates a novel pathway that Rabeprazole regulates barrier function in gastric epithelial cells. Mechanistically, Rabeprazole treatment led to a downregulation of STAT3 and FOXF1 phosphorylation, leading to inhibit nuclear translocation and decrease the binding of STAT3 and FOXF1 to ZO-1 promoter, respectively. Most important, endogenous FOXF1 interacted with STAT3, and this interaction was dramatically abolished by Rabeprazole stimulation. Overexpression of STAT3 and FOXF1 in GES-1 cells reversed the inhibitory effect of Rabeprazole on ZO-1 expression, respectively. These finding extended the function of Rabeprazole and established a previously unappreciated mechanism by which the Rabeprazole/FOXF1/STAT3 axis facilitated ZO-1 expression to regulate barrier function, and a comprehensive consideration and evaluation was required in treatment of patients.

JAKs and STATs from a Clinical Perspective: Loss-of-Function Mutations, Gain-of-Function Mutations, and Their Multidimensional Consequences

The JAK/STAT signaling pathway plays a key role in cytokine signaling and is involved in development, immunity, and tumorigenesis for nearly any cell. At first glance, the JAK/STAT signaling pathway appears to be straightforward. However, on closer examination, the factors influencing the JAK/STAT signaling activity, such as cytokine diversity, receptor profile, overlapping JAK and STAT specificity among non-redundant functions of the JAK/STAT complexes, positive regulators (e.g., cooperating transcription factors), and negative regulators (e.g., SOCS, PIAS, PTP), demonstrate the complexity of the pathway's architecture, which can be quickly disturbed by mutations. The JAK/STAT signaling pathway has been, and still is, subject of basic research and offers an enormous potential for the development of new methods of personalized medicine and thus the translation of basic molecular research into clinical practice beyond the use of JAK inhibitors. Gain-of-function and loss-of-function mutations in the three immunologically particularly relevant signal transducers STAT1, STAT3, and STAT6 as well as JAK1 and JAK3 present themselves through individual phenotypic clinical pictures. The established, traditional paradigm of loss-of-function mutations leading to immunodeficiency and gain-of-function mutation leading to autoimmunity breaks down and a more differentiated picture of disease patterns evolve. This review is intended to provide an overview of these specific syndromes from a clinical perspective and to summarize current findings on pathomechanism, symptoms, immunological features, and therapeutic options of STAT1, STAT3, STAT6, JAK1, and JAK3 loss-of-function and gain-of-function diseases.

Autoimmune Cytopenias and Dysregulated Immunophenotype Act as Warning Signs of Inborn Errors of Immunity: Results From a Prospective Study

Inborn errors of immunity (IEI) are genetic disorders characterized by a wide spectrum of clinical manifestations, ranging from increased susceptibility to infections to significant immune dysregulation. Among these, primary immune regulatory disorders (PIRDs) are mainly presenting with autoimmune manifestations, and autoimmune cytopenias (AICs) can be the first clinical sign. Significantly, AICs in patients with IEI often fail to respond to first-line therapy. In pediatric patients, autoimmune cytopenias can be red flags for IEI. However, for these cases precise indicators or parameters useful to suspect and screen for a hidden congenital immune defect are lacking. Therefore, we focused on chronic/refractory AIC patients to perform an extensive clinical evaluation and multiparametric flow cytometry analysis to select patients in whom PIRD was strongly suspected as candidates for genetic analysis. Key IEI-associated alterations causative of STAT3 GOF disease, IKAROS haploinsufficiency, activated PI3Kδ syndrome (APDS), Kabuki syndrome and autoimmune lymphoproliferative syndrome (ALPS) were identified. In this scenario, a dysregulated immunophenotype acted as a potential screening tool for an early IEI diagnosis, pivotal for appropriate clinical management and for the identification of new therapeutic targets.

ALPS, FAS, and beyond: from inborn errors of immunity to acquired immunodeficiencies

Autoimmune lymphoproliferative syndrome (ALPS) is a primary immune regulatory disorder characterized by benign or malignant lymphoproliferation and autoimmunity. Classically, ALPS is due to mutations in FAS and other related genes; however, recent research revealed that other genes could be responsible for similar clinical features. Therefore, ALPS classification and diagnostic criteria have changed over time, and several ALPS-like disorders have been recently identified. Moreover, mutations in FAS often show an incomplete penetrance, and certain genotypes have been associated to a dominant or recessive inheritance pattern. FAS mutations may also be acquired or could become pathogenic when associated to variants in other genes, delineating a possible digenic type of inheritance. Intriguingly, variants in FAS and increased TCR αβ double-negative T cells (DNTs, a hallmark of ALPS) have been identified in multifactorial autoimmune diseases, while FAS itself could play a potential role in carcinogenesis. These findings suggest that alterations of FAS-mediated apoptosis could trespass the universe of inborn errors of immunity and that somatic mutations leading to ALPS could only be the tip of the iceberg of acquired immunodeficiencies.

Autosomal dominant chronic mucocutaneous candidiasis with STAT1 mutation can be associated with chronic active hepatitis: A case report

BACKGROUND

Chronic mucocutaneous candidiasis (CMC) is a heterogeneous primary immunodeficiency disease characterized by chronic or recurrent Candida infections of the skin, nails, and mucosa and is mostly associated with STAT1 gain-of-function (GOF) mutation (GOF-STAT1 mutation).

CASE PRESENTATION

A two-year-old girl was presented with recurrent liver dysfunction, oral candidiasis, acute bronchial pneumonia, and cytomegalovirus infection. Even after a series of treatments, including antifungal voriconazole, nystatin treatment for oral Candida, antibiotics against bacterial infection, and bicyclol to protect the liver, the child still exhibited signs of splenomegaly. Although we performed relevant etiological tests on the child and conducted histopathology and electron microscopic examination of the liver, we could not explain the clinical symptoms. So, a genetic test was conducted to clarify the diagnosis. Since the child suffered recurrent fungal infections, we speculated that she had combined immunodeficiency. Therefore we performed high-precision clinical display PLUS detection and found that the transcription factor STAT1 had a heterozygous GOF mutation (p. R274W) in its coiled-coil domain.

CONCLUSION

The clinical manifestations of chronic mucocutaneous candidiasis caused by GOF-STAT1 mutations are complex and range from mild local fungal infections to severe systemic diseases and are sometimes fatal. Clinicians need to be aware of the possibility of this disease in children with recurrent fungal infections for early diagnosis and treatment.

STAT proteins: a kaleidoscope of canonical and non-canonical functions in immunity and cancer

STAT proteins represent an important family of evolutionarily conserved transcription factors that play key roles in diverse biological processes, notably including blood and immune cell development and function. Classically, STAT proteins have been viewed as inducible activators of transcription that mediate cellular responses to extracellular signals, particularly cytokines. In this 'canonical' paradigm, latent STAT proteins become tyrosine phosphorylated following receptor activation, typically via downstream JAK proteins, facilitating their dimerization and translocation into the nucleus where they bind to specific sequences in the regulatory region of target genes to activate transcription. However, growing evidence has challenged this paradigm and identified alternate 'non-canonical' functions, such as transcriptional repression and roles outside the nucleus, with both phosphorylated and unphosphorylated STATs involved. This review provides a revised framework for understanding the diverse kaleidoscope of STAT protein functional modalities. It further discusses the implications of this framework for our understanding of STAT proteins in normal blood and immune cell biology and diseases such as cancer, and also provides an evolutionary context to place the origins of these alternative functional modalities.

The New "Wholly Trinity" in the Diagnosis and Management of Inborn Errors of Immunity

The field of immunology has a rich and diverse history, and the study of inborn errors of immunity (IEIs) represents both the "cake" and the "icing on top of the cake," as it has enabled significant advances in our understanding of the human immune system. This explosion of knowledge has been facilitated by a unique partnership, a triumvirate formed by the physician who gathers detailed immunological and clinical phenotypic information from, and shares results with, the patient; the laboratory scientist/immunologist who performs diagnostic testing, as well as advanced functional correlative studies; and the genomics scientist/genetic counselor, who conducts and interprets varied genetic analyses, all of which are essential for dissecting constitutional genetic disorders. Although the basic principles of clinical care have not changed in recent years, the practice of clinical immunology has changed to reflect the prodigious advances in diagnostics, genomics, and therapeutics. An "omic/tics"-centric approach to IEI reflects the tremendous strides made in the field in the new millennium with recognition of new disorders, characterization of the molecular underpinnings, and development and implementation of personalized treatment strategies. This review brings renewed attention to bear on the indispensable "trinity" of phenotypic, genomic, and immunological analyses in the diagnosis, management, and treatment of IEIs.

Primary Immune Regulatory Disorders and Targeted Therapies

Primary immune regulatory disorders (PIRDs) are a group of diseases belonging to inborn errors of immunity. They usually exhibit lymphoproliferation, autoimmunities, and malignancies, with less susceptibility to recurrent infections. Unlike classical primary immune deficiencies, in autoimmune manifestations, such as cytopenias, enteropathy can be the first symptom of diseases, and they are typically resistant to treatment. Increasing awareness of PIRDs among specialists and a multidisciplinary team approach would provide early diagnosis and treatment that could prevent end-organ damage related to the diseases. In recent years, many PIRDs have been described, and understanding the immunological pathways linked to these disorders provides us an opportunity to use directed therapies for specific molecules, which usually offer better disease control than known classical immunosuppressants. In this review, in light of the most recent literature, we will discuss the common PIRDs and explain their clinical symptoms and recent treatment modalities.

Chronic Candida infection, bronchiectasis, immunoglobulin abnormalities, and stunting: a case report of a natural mutation of STAT1 (c.986C>G) in an adolescent male

Background

Chronic mucocutaneous candidiasis (CMC) is the most common clinical symptom of singer transducer and signal transducer and activator of transcription 1 (STAT1) gain-of-function (GOF) mutations. Bronchiectasis is a chronic lung disease that is characterized by permanent bronchiectasis, causing cough, expectoration, and even haemoptysis. The underlying pathogeny is not yet clear. Immunoglobulin (Ig) A is derived from memory B cells and correlates with immune-related diseases. STAT1 is closely associated with signal transmission and immune regulation.

Case presentation

We report a 17-year-old male patient carrying a GOF mutation in STAT1. The variant led to CMC, bronchiectasis, and elevated serum IgA levels, as well as stunting. Whole-exome sequencing (WES) revealed a c.986C>G (p.P329R) heterozygous mutation in the STAT1 gene.

Conclusion

Further Sanger sequencing analysis of STAT1 in the patient and his parents showed that the patient harboured a de novo mutation.

Atypical Presentations of IPEX: Expect the Unexpected

Immune dysregulation, polyendocrinopathy, and enteropathy, X-linked (IPEX) syndrome is a rare disorder that has become a model of monogenic autoimmunity. IPEX is caused by mutations in FOXP3 gene, a master regulator of regulatory T cells (Treg). Cases reported in the last 20 years demonstrate that IPEX clinical spectrum encompasses more than the classical triad of early-onset intractable diarrhea, type 1 diabetes (T1D) and eczema. Atypical cases of IPEX include patients with late-onset of symptoms, single-organ involvement, mild disease phenotypes or rare clinical features (e.g., atrophic gastritis, interstitial lung disease, nephropathy etc.). Several atypical presentations have recently been reported, suggesting that IPEX incidence might be underestimated. Immunosuppression (IS) treatment strategies can control the disease, however at the moment allogeneic hematopoietic stem cell transplantation (HSCT) is the only available definitive cure, therefore it is important to achieve a prompt diagnosis. This review aims to describe unusual clinical phenotypes, beyond classical IPEX. Overall, our analysis contributes to increase awareness and finally improve diagnosis and treatment intervention in IPEX in order to ensure a good quality of life.

IL-2 Signaling Axis Defects: How Many Faces?

CD25, Signal transducer and activator of transcription 5B (STAT5B) and Forkhead box P3 (FOXP3) are critical mediators of Interleukin-2 (IL-2) signaling pathway in regulatory T cells (Tregs). CD25 (i.e., IL-2 Receptor α) binds with high affinity to IL-2, activating STAT5B-mediated signaling that eventually results in transcription of FOXP3, a master regulator of Treg function. Consequently, loss-of-function mutations in these proteins give rise to Treg disorders (i.e., Tregopathies) that clinically result in multiorgan autoimmunity. Immunodysregulation, Polyendocrinopathy Enteropathy X-linked (IPEX), due to mutations in FOXP3, has historically been the prototype of Tregopathies. This review describes current knowledge about defects in CD25, STAT5B, and FOXP3, highlighting that these disorders both share a common biological background and display comparable clinical features. However, specific phenotypes are associated with each of these syndromes, while certain laboratory findings could be helpful tools for clinicians, in order to achieve a prompt genetic diagnosis. Current treatment strategies will be outlined, keeping an eye on gene editing, an interesting therapeutic perspective that could definitely change the natural history of these disorders.

STAT3 and STAT5B Mutations in T/NK-Cell Chronic Lymphoproliferative Disorders of Large Granular Lymphocytes (LGL): Association with Disease Features

Simple Summary

STAT3 and STAT5B mutations have been identified in a subset of T and NK large granular lymphocytic leukemia (T/NK-LGLL). The aim of our study was to evaluate the frequency and type of these mutations in all different subtypes of T/NK-LGL expansions (n = 100 patients), as well as to analyze its association with biological and clinical features of the disease. We show for the first time that STAT3/5B mutations were present in all different T/NK-cell LGLL categories here studied; further, STAT3 mutations were associated with overall reduced counts of almost all normal residual populations of immune cells in blood, together with a shorter time-to-therapy vs. wild type T/NK-LGLL. These findings contribute to support the utility of the STAT3 mutation analysis for diagnostic and prognostic purposes in LGLL.

Abstract

STAT3 and STAT5B (STAT3/STAT5B) mutations are the most common mutations in T-cell large granular lymphocytic leukemia (T-LGLL) and chronic lymphoproliferative disorders of NK cells (CLPD-NK), but their clinical impact remains unknown. We investigated the frequency and type of STAT3/STAT5B mutations in FACS-sorted populations of expanded T/NK-LGL from 100 (82 clonal; 6 oligoclonal; 12 polyclonal) patients, and its relationship with disease features. Seventeen non-LGL T-CLPD patients and 628 age-matched healthy donors were analyzed as controls. STAT3 (n = 30) and STAT5B (n = 1) mutations were detected in 28/82 clonal T/NK-LGLL patients (34%), while absent (0/18, 0%) among oligoclonal/polyclonal LGL-lymphocytosis. Mutations were found across all diagnostic subgroups: TCD8⁺-LGLL, 36%; CLPD-NK, 38%; TCD4⁺-LGLL, 7%; Tαβ⁺DP-LGLL, 100%; Tαβ⁺DN-LGLL, 50%; Tγδ⁺-LGLL, 44%. STAT3-mutated T-LGLL/CLPD-NK showed overall reduced (p < 0.05) blood counts of most normal leukocyte subsets, with a higher rate (vs. nonmutated LGLL) of neutropenia (p = 0.04), severe neutropenia (p = 0.02), and cases requiring treatment (p = 0.0001), together with a shorter time-to-therapy (p = 0.0001), particularly in non-Y640F STAT3-mutated patients. These findings confirm and extend on previous observations about the high prevalence of STAT3 mutations across different subtypes of LGLL, and its association with a more marked decrease of all major blood-cell subsets and a shortened time-to-therapy.

Papilledema from gain-of-function mutations in the STAT3 gene

BACKGROUND

Signal Transducer and Activator of Transcription 3 (STAT3) gain-of-function germline mutations are associated with diverse clinical manifestations, including autoimmune cytopenia, lymphadenopathy, immunodeficiency, endocrinopathy, and enteropathy. We describe a new feature: raised intracranial pressure with papilledema.

MATERIALS AND METHODS

Report of two cases.

RESULTS

The first patient had a de novo heterozygous c.2144C>T (p.Pro715Leu) mutation in the STAT3 gene. At age 1 she had papilledema with marked sheathing of the proximal vessels on the optic discs. Follow-up 8 years later showed chronic papilledema, cystoid macular edema, and vision loss. The second patient had a de novo heterozygous c.2147C>T (p.Thr716Met) mutation. At age 12 he developed papilledema, which recurred despite treatment. In both patients, repeated sampling of the cerebrospinal fluid demonstrated a lymphocytic pleocytosis.

CONCLUSIONS

Papilledema can occur as a manifestation of STAT3 gain-of-function mutation, sometimes accompanied by prominent vascular sheathing and cystoid macular edema. The mechanism may be chronic meningeal infiltration by white blood cells, impairing cerebrospinal fluid absorption.

Repercussions of inborn errors of immunity on growth

OBJECTIVES

This study aimed to review the literature on the repercussions of the different inborn errors of immunity on growth, drawing attention to the diagnosis of this group of diseases in patients with growth disorders, as well as to enable the identification of the different causes of growth disorders in patients with inborn errors of immunity, which can help in their treatment.

DATA SOURCES

Non-systematic review of the literature, searching articles since 2000 in PubMed with the terms "growth", "growth disorders", "failure to thrive", or "short stature" AND "immunologic deficiency syndromes", "immune deficiency disease", or "immune deficiency" NOT HIV. The Online Mendelian Inheritance in Man (OMIN) database was searched for immunodeficiencies and short stature or failure to thrive.

DATA SUMMARY

Inborn errors of immunity can affect growth in different ways, and some of them can change growth through multiple simultaneous mechanisms: genetic syndromes; disorders of the osteoarticular system; disorders of the endocrine system; reduction in caloric intake; catabolic processes; loss of nutrients; and inflammatory and/or infectious conditions.

CONCLUSIONS

The type of inborn errors of immunity allows anticipating what type of growth disorder can be expected. The type of growth disorder can help in the diagnosis of clinical conditions related to inborn errors of immunity. In many inborn errors of immunity, the causes of poor growth are mixed, involving more than one factor. In many cases, impaired growth can be adjusted with proper inborn errors of immunity treatment or proper approach to the mechanism of growth impairment.

Gain-of-Function STAT1 Mutation With Familial Lymphadenopathy and Hodgkin Lymphoma

In this report, we describe a novel T437N STAT1 mutation found in a mother and 3 of her 4 children which we demonstrate yields gain-of-function. All of the four patients with the T437N STAT1 mutation experienced lymphadenopathy. However, two of the children developed Nodular Lymphocyte Predominant Hodgkin Lymphoma (NHLPL) and have responded to chemotherapeutic regimens. The fourth sibling had neither the STAT1 variant nor lymphadenopathy or malignancy. To our knowledge this is the first description of a potential association between STAT1 GOF mutations and lymphoma development.

STAT1 and STAT3 mutations: important lessons for clinical immunologists

INTRODUCTION

The transcription factors signal transducer and activator of transcription (STAT) 1 and STAT3 fulfill fundamental functions in nonimmune and immune cells. The description and follow-up of patients with germline mutations that result in either loss-of-function or gain-of-function have contributed to our understanding of the pathophysiology of these regulators. Depending on the type of mutations, clinical symptoms are complex and can include infection susceptibility, immune dysregulation as well as characteristic nonimmune features. Areas covered: In this review, we provide an overview about mechanistic concepts, clinical manifestations, diagnostic process, and traditional as well as innovative treatment options aiming to help the clinical immunologist to better understand and manage these complex and rare diseases. Clinical and research papers were identified and summarized through PubMed Internet searches, and expert opinions are provided. Expert commentary: The last several years have seen an explosion in the clinical descriptions and pathogenesis knowledge of the diseases caused by GOF and LOF mutations in STAT1 and STAT3. However, harmonization of laboratory testing and follow-up in international cohorts is needed to increase our knowledge about the natural history of these disorders as well as the development of curative or supportive targeted therapies.

Translational and clinical advances in JAK-STAT biology: The present and future of jakinibs

In this era, it is axiomatic that cytokines have critical roles in cellular development and differentiation, immune homeostasis, and host defense. Equally, dysregulation of cytokines is known to contribute to diverse inflammatory and immune-mediated disorders. In fact, the past 20 years have witnessed the rapid translation of basic discoveries in cytokine biology to multiple successful biological agents (mAbs and recombinant fusion proteins) that target cytokines. These targeted therapies have not only fundamentally changed the face of multiple immune-mediated diseases but have also unequivocally established the role of specific cytokines in human disease; cytokine biologists have many times over provided remarkable basic advances with direct clinical benefit. Numerous cytokines rely on the JAK-STAT pathway for signaling, and new, safe, and effective small molecule inhibitors have been developed for a range of disorders. In this review, we will briefly summarize basic discoveries in cytokine signaling and briefly comment on some major unresolved issues. We will review clinical data pertaining to the first generation of JAK inhibitors and their clinical indications, discuss additional opportunities for targeting this pathway, and lay out some of the challenges that lie ahead.

Bacille Calmette-Guerin Complications in Newly Described Primary Immunodeficiency Diseases: 2010-2017

Bacille Calmette–Guerin (BCG) vaccine is widely used as a prevention strategy against tuberculosis. BCG is a live vaccine, usually given early in life in most countries. While safe to most recipients, it poses a risk to immunocompromised patients. Several primary immunodeficiency diseases (PIDD) have been classically associated with complications related to BCG vaccine. However, a number of new inborn errors of immunity have been described lately in which little is known about adverse reactions following BCG vaccination. The aim of this review is to summarize the existing data on BCG-related complications in patients diagnosed with PIDD described since 2010. When BCG vaccination status or complications were not specifically addressed in those manuscripts, we directly contacted the corresponding authors for further clarification. We also analyzed data on other mycobacterial infections in these patients. Based on our analysis, around 8% of patients with gain-of-function mutations in STAT1 had mycobacterial infections, including localized complications in 3 and disseminated disease in 4 out of 19 BCG-vaccinated patients. Localized BCG reactions were also frequent in activated PI3Kδ syndrome type 1 (3/10) and type 2 (2/18) vaccinated children. Also, of note, no BCG-related complications have been described in either CTLA4 or LRBA protein-deficient patients; and not enough information on BCG-vaccinated NFKB1 or NFKB2-deficient patients was available to drive any conclusions about these diseases. Despite the high prevalence of environmental mycobacterial infections in GATA2-deficient patients, only one case of BCG reaction has been reported in a patient who developed disseminated disease. In conclusion, BCG complications could be expected in some particular, recently described PIDD and it remains a preventable risk factor for pediatric PIDD patients.