Gastrointestinal Manifestations in X-linked Agammaglobulinemia

Investigating the molecular mechanisms underlying the co-occurrence of Parkinson's disease and inflammatory bowel disease through the integration of multiple datasets

Parkinson's disease (PD) and inflammatory bowel disease (IBD) are chronic diseases affecting the central nervous system and gastrointestinal tract, respectively. Recent research suggests a bidirectional relationship between neurodegeneration in PD and intestinal inflammation in IBD. PD patients may experience gastrointestinal dysfunction over a decade before motor symptom onset, and IBD may increase the risk of developing PD. Despite the "gut-brain axis" concept, the underlying pathophysiological mechanisms of this potential association remain unclear. This study aimed to investigate the biological mechanisms of differentially expressed genes in PD and IBD using bioinformatics tools, providing novel insights into the co-diagnosis and treatment of these diseases. We constructed a gene marker for disease diagnosis and identified five important genes (BTK, NCF2, CRH, FCGR3A and SERPINA3). Through nomogram and decision tree analyses, we found that both the IBD and PD required only the expression levels of BTK and NCF2 for accurate discrimination. Additionally, small molecule drugs RO-90-7501 and MST-312 may be useful for the treatment of both IBD and PD. These findings offer new perspectives on the co-diagnosis and treatment of PD and IBD, and suggest that targeting BTK may be a promising therapeutic strategy for both diseases.

Chronic Lymphocytic Leukemia: Management of Adverse Events in the Era of Targeted Agents

The treatment landscape for CLL has undergone a profound transformation with the advent of targeted agents (TAs) like Bruton's Tyrosine Kinase inhibitors (BTKis) and BCL-2 inhibitors (BCL-2is). These agents target crucial cellular pathways in CLL, offering superior efficacy over traditional chemo-immunotherapy, which has led to improved progression-free and overall survival rates. This advancement promises enhanced disease control and potentially normal life expectancy for many patients. However, the journey is not without challenges, as these TAs are associated with a range of adverse events (AEs) that can impact treatment efficacy and patient quality of life. This review focuses on detailing the various AEs related to TA management in CLL, evaluating their frequency and clinical impact. The aim is to present a comprehensive guide to the effective management of these AEs, ensuring optimal tolerability and efficacy of TAs. By reviewing the existing literature and consolidating findings, we provide insights into AE management, which is crucial for maximizing patient outcomes in CLL therapy.

Precision medicine in monogenic inflammatory bowel disease: proposed mIBD REPORT standards

Owing to advances in genomics that enable differentiation of molecular aetiologies, patients with monogenic inflammatory bowel disease (mIBD) potentially have access to genotype-guided precision medicine. In this Expert Recommendation, we review the therapeutic research landscape of mIBD, the reported response to therapies, the medication-related risks and systematic bias in reporting. The mIBD field is characterized by the absence of randomized controlled trials and is dominated by retrospective observational data based on case series and case reports. More than 25 off-label therapeutics (including small-molecule inhibitors and biologics) as well as cellular therapies (including haematopoietic stem cell transplantation and gene therapy) have been reported. Heterogeneous reporting of outcomes impedes the generation of robust therapeutic evidence as the basis for clinical decision making in mIBD. We discuss therapeutic goals in mIBD and recommend standardized reporting (mIBD REPORT (monogenic Inflammatory Bowel Disease Report Extended Phenotype and Outcome of Treatments) standards) to stratify patients according to a genetic diagnosis and phenotype, to assess treatment effects and to record safety signals. Implementation of these pragmatic standards should help clinicians to assess the therapy responses of individual patients in clinical practice and improve comparability between observational retrospective studies and controlled prospective trials, supporting future meta-analysis.

Chronic Diarrhea with Villous Blunting of the Small Intestine Under Capsule Endoscopy in Common Variable Immunodeficiency and X-Linked Agammaglobulinemia: A Case Series

Introduction

Primary immunodeficiencies (PIDs) are a heterogeneous group of disorders, common variable immunodeficiency disorder (CVID) and X-linked agammaglobulinemia (XLA) are PIDs related to B-cell defect, characterized by reduced levels of immunoglobulins and immune dysregulation. Infections are the most common clinical manifestations, while underlying autoimmune and inflammatory conditions are present in some patients with CVID and XLA, leading to clinical misdiagnosis and diagnostic delay. Chronic diarrhea in patients with CVID and XLA, particularly complicated malabsorption and protein-energy malnutrition, is responsible for poor prognostic outcomes.

Methods

In this study, we described three PID adult patients (two with CVID and one with XLA) who presented with varying degrees of chronic diarrhea, weight loss, and protein-energy malnutrition. We suggest that villous blunting of the small intestine under capsule endoscopy may be an endoscopic feature of PID-related enteropathy, thus highlighting the application of capsule endoscopy in patients with CVID and XLA presenting with chronic diarrhea.

Conclusion

We also summarize regular Ig supplementation is the basic treatment for CVID and XLA patients, proper enteral nutrition and probiotic therapy can be explored to use to alter gut microbiota and modulate intestinal immune response. However, vedolizumab is not helpful to PID-related enteropathy therapy, as it exacerbates the inflammatory response in extra-intestinal organs and ultimately causes poor clinical outcomes.

A Registry Study of 240 Patients with X-Linked Agammaglobulinemia Living in the USA

PURPOSE

To understand the natural history and clinical outcomes for patients with X-linked agammaglobulinemia (XLA) in the United States utilizing the United States Immunodeficiency Network (USIDNET) patient registry.

METHODS

The USIDNET registry was queried for data from XLA patients collected from 1981 to 2019. Data fields included demographics, clinical features before and after diagnosis of XLA, family history, genetic mutation in Bruton's tyrosine kinase (BTK), laboratory findings, treatment modalities, and mortality.

RESULTS

Data compiled through the USIDNET registry on 240 patients were analyzed. Patient year of birth ranged from 1945 to 2017. Living status was available for 178 patients; 158/178 (88.8%) were alive. Race was reported for 204 patients as follows: White, 148 (72.5%); Black/African American, 23 (11.2%); Hispanic, 20 (9.8%); Asian or Pacific Islander, 6 (2.9%), and other or more than one race, 7 (3.4%). The median age at last entry, age at disease onset, age at diagnosis, and length of time with XLA diagnosis was 15 [range (r) = 1-52 years], 0.8 [r = birth-22.3 years], 2 [r = birth-29 years], and 10 [r = 1-56 years] years respectively. One hundred and forty-one patients (58.7%) were < 18 years of age. Two hundred and twenty-one (92%) patients were receiving IgG replacement (IgGR), 58 (24%) were on prophylactic antibiotics, and 19 (7.9%) were on immunomodulatory drugs. Eighty-six (35.9%) patients had undergone surgical procedures, two had undergone hematopoietic cell transplantation, and two required liver transplantation. The respiratory tract was the most affected organ system (51.2% of patients) followed by gastrointestinal (40%), neurological (35.4%), and musculoskeletal (28.3%). Infections were common both before and after diagnosis, despite IgGR therapy. Bacteremia/sepsis and meningitis were reported more frequently before XLA diagnosis while encephalitis was more commonly reported after diagnosis. Twenty patients had died (11.2%). The median age of death was 21 years (range = 3-56.7 years). Neurologic condition was the most common underlying co-morbidity for those XLA patients who died.

CONCLUSIONS

Current therapies for XLA patients reduce early mortality, but patients continue to experience complications that impact organ function. With improved life expectancy, more efforts will be required to improve post-diagnosis organ dysfunction and quality of life. Neurologic manifestations are an important co-morbidity associated with mortality and not yet clearly fully understood.

Immune tolerance breakdown in inborn errors of immunity: Paving the way to novel therapeutic approaches

Up to 25% of the patients with inborn errors of immunity (IEI) also exhibit immunodysregulatory features. The association of immune dysregulation and immunodeficiency may be explained by different mechanisms. The understanding of mechanisms underlying immune dysregulation in IEI has paved the way for the development of targeted treatments. In this review article, we will summarize the mechanisms of immune tolerance breakdown and the targeted therapeutic approaches to immune dysregulation in IEI.

Immunosuppression in Patients With Primary Immunodeficiency-Walking the Line

Individuals with primary immunodeficiency (PIDD) experience not only infectious complications but also immune dysregulation leading to autoimmunity, inflammation, and lymphoproliferative manifestations. Management of these complications often requires treatment with additional immunosuppressive medications, which pose an additional risk of infectious complications. Immunosuppression in individuals with PIDD therefore requires careful assessment and consideration of risks and benefits. Medications should be closely monitored, and strategies for risk mitigation of adverse events considered, such as exposure reduction, appropriate vaccination, use of antibiotics/antivirals, and optimization of immunoglobulin replacement therapy. In a subset of individuals who are not tolerating immune modulation or experiencing disease progression despite appropriate interventions, hematopoietic stem-cell transplantation is a management option.

Autoimmunity in Primary Immunodeficiencies (PID)

Primary immunodeficiency (PID) may impact any component of the immune system. The number of PID and immune dysregulation disorders is growing steadily with advancing genetic detection methods. These expansive recognition methods have changed the way we characterize PID. While PID were once characterized by their susceptibility to infection, the increase in genetic analysis has elucidated the intertwined relationship between PID and non-infectious manifestations including autoimmunity. The defects permitting opportunistic infections to take hold may also lead the way to the development of autoimmune disease. In some cases, it is the non-infectious complications that may be the presenting sign of PID autoimmune diseases, such as autoimmune cytopenia, enteropathy, endocrinopathies, and arthritis among others, have been reported in PID. While autoimmunity may occur with any PID, this review will look at certain immunodeficiencies most often associated with autoimmunity, as well as their diagnosis and management strategies.

Agammaglobulinemia: from X-linked to Autosomal Forms of Disease

Interruptions or alterations in the B cell development pathway can lead to primary B cell immunodeficiency with resultant absence or diminished immunoglobulin production. While the most common cause of congenital agammaglobulinemia is X-linked agammaglobulinemia (XLA), accounting for approximately 85% of cases, other genetic forms of agammaglobulinemia have been identified. Early recognition and diagnosis of these conditions are pivotal for improved outcomes and prevention of sequelae and complications. The diagnosis of XLA is often delayed, and can be missed if patient has a mild phenotype. The lack of correlation between phenotype and genotype in this condition makes management and predicting outcomes quite difficult. In contrast, while less common, autosomal recessive forms of agammaglobulinemia present at younger ages and with typically more severe clinical features resulting in an earlier diagnosis. Some diagnostic innovations, such as KREC level measurements and serum BCMA measurements, may aid in facilitating an earlier identification of agammaglobulinemia leading to prompt treatment. Earlier diagnosis may improve the overall health of patients with XLA.

Nodular regenerative hyperplasia in X-linked agammaglobulinemia: An underestimated and severe complication

BACKGROUND

Late-onset complications in X-linked agammaglobulinemia (XLA) are increasingly recognized. Nodular regenerative hyperplasia (NRH) has been reported in primary immunodeficiency but data in XLA are limited.

OBJECTIVES

This study sought to describe NRH prevalence, associated features, and impact in patients with XLA.

METHODS

Medical records of all patients with XLA referred to the National Institutes of Health between October 1994 and June 2019 were reviewed. Liver biopsies were performed when clinically indicated. Patients were stratified into NRH+ or NRH- groups, according to their NRH biopsy status. Fisher exact test and Mann-Whitney test were used for statistical comparisons.

RESULTS

Records of 21 patients with XLA were reviewed, with a cumulative follow-up of 129 patient-years. Eight patients underwent ≥1 liver biopsy of whom 6 (29% of the National Institutes of Health XLA cohort) were NRH+. The median age at NRH diagnosis was 20 years (range, 17-31). Among patients who had liver biopsies, alkaline phosphatase levels were only increased in patients who were NRH+ (P = .04). Persistently low platelet count (<100,000 per μL for >6 months), mildly to highly elevated hepatic venous pressure gradient and either hepatomegaly and/or splenomegaly were present in all patients who were NRH+. In opposition, persistently low platelet counts were not seen in patients who were NRH-, and hepatosplenomegaly was observed in only 1 patient who was NRH-. Hepatic venous pressure gradient was normal in the only patient tested who was NRH-. All-cause mortality was higher among patients who were NRH+ (5 of 6, 83%) than in the rest of the cohort (1 of 15, 7% among patients who were NRH- and who were classified as unknown; P = .002).

CONCLUSIONS

NRH is an underreported, frequent, and severe complication in XLA, which is associated with increased morbidity and mortality.

Monogenic Adult-Onset Inborn Errors of Immunity

Inborn errors of immunity (IEI) are a heterogenous group of disorders driven by genetic defects that functionally impact the development and/or function of the innate and/or adaptive immune system. The majority of these disorders are thought to have polygenic background. However, the use of next-generation sequencing in patients with IEI has led to an increasing identification of monogenic causes, unravelling the exact pathophysiology of the disease and allowing the development of more targeted treatments. Monogenic IEI are not only seen in a pediatric population but also in adulthood, either due to the lack of awareness preventing childhood diagnosis or due to a delayed onset where (epi)genetic or environmental factors can play a role. In this review, we discuss the mechanisms accounting for adult-onset presentations and provide an overview of monogenic causes associated with adult-onset IEI.

Intestinal immunoregulation: lessons from human mendelian diseases

The mechanisms that maintain intestinal homeostasis despite constant exposure of the gut surface to multiple environmental antigens and to billions of microbes have been scrutinized over the past 20 years with the goals to gain basic knowledge, but also to elucidate the pathogenesis of inflammatory bowel diseases (IBD) and to identify therapeutic targets for these severe diseases. Considerable insight has been obtained from studies based on gene inactivation in mice as well as from genome wide screens for genetic variants predisposing to human IBD. These studies are, however, not sufficient to delineate which pathways play key nonredundant role in the human intestinal barrier and to hierarchize their respective contribution. Here, we intend to illustrate how such insight can be derived from the study of human Mendelian diseases, in which severe intestinal pathology results from single gene defects that impair epithelial and or hematopoietic immune cell functions. We suggest that these diseases offer the unique opportunity to study in depth the pathogenic mechanisms leading to perturbation of intestinal homeostasis in humans. Furthermore, molecular dissection of monogenic intestinal diseases highlights key pathways that might be druggable and therapeutically targeted in common forms of IBD.

Haematopoietic Stem Cell Transplant for Norovirus-Induced Intestinal Failure in X-linked Agammaglobulinemia

Since the first clinical description in 1952, immunoglobulin replacement therapy remains the mainstay of treatment of patients with X-linked agammaglobulinemia (XLA). However, this therapy only replaces IgG isotype and does not compensate for the loss of Bruton tyrosine kinase in non-B-lymphocytes. Patients may still therefore develop complications despite current standard of care. Here, we describe an XLA patient with persistent chronic norovirus infection, refractory to treatment and causing intestinal failure. The patient underwent haematopoietic stem cell transplantation, curing XLA and allowed clearance of norovirus prior to humoral immunoreconstitution, suggesting non-humoral immunodeficiency in these patients.

Inflammatory bowel disease in primary immunodeficiency disorders is a heterogeneous clinical entity requiring an individualized treatment strategy: A systematic review

OBJECTIVE

To describe the prevalence, clinical presentation and current treatment regimens of inflammatory bowel disease (IBD) in patients with primary immunodeficiency disorders (PIDs).

METHODS

A systematic review was conducted. The following databases were searched: MEDLINE, Embase, Web of Science, the Cochrane Library and Google Scholar.

RESULTS

A total of 838 articles were identified, of which 36 were included in this review. The prevalence of IBD in PIDs ranges between 3.4% and 61.2%, depending on the underlying PID. Diarrhea and abdominal pain were reported in 64.3% and 52.4% of the patients, respectively. Colon ulceration was the most frequent finding on endoscopic evaluation, while cryptitis, granulomas, ulcerations and neutrophilic/lymphocytic infiltrates were the most frequently reported histopathological abnormalities. Described treatment regimens included oral corticosteroids and other oral immunosuppressive agents, including mesalazine, azathioprine and cyclosporin, leading to clinical improvement in the majority of patients. In case of treatment failure, biological therapies including TNF- α blocking agents, are considered.

CONCLUSIONS

The overall prevalence of IBD in patients with PID is high, but varies between different PIDs. Physicians should be aware of these complications and focus on characteristic symptoms to reduce diagnostic delay and delay in initiation of treatment. Treatment of IBD in PIDs depends on severity of symptoms and may differ between various PIDs based on distinct underlying pathogenesis. An individualized diagnostic and therapeutic approach is therefore warranted.

Crohn's-like Enteritis in X-Linked Agammaglobulinemia: A Case Series and Systematic Review

BACKGROUND

X-linked agammaglobulinemia (XLA) is an inherited primary immunodeficiency that usually manifests clinically with recurrent sinopulmonary infections. Gastrointestinal manifestations are mostly driven by acute infections and disturbed mucosal immunity, but there is a notable prevalence of inflammatory bowel disease (IBD). Differentiating between XLA-associated enteritis, which can originate from recurrent infections, and IBD can be diagnostically and therapeutically challenging.

OBJECTIVE

This study presents a critical appraisal of the clinical, radiological, endoscopic, and histological features associated with XLA-associated Crohn disease (CD)-like enteritis.

METHODS

We report 3 cases and performed a systematic review of the literature describing the diagnoses and outcomes.

RESULTS

An XLA-related enteropathy presented in adolescence with an ileocolonic CD-like phenotype without perianal disease. Abdominal pain, noninfectious diarrhea, and weight loss were the most common symptoms. Imaging and endoscopic findings closely resemble CD. However, histologically, it presents without nodular lymphoid hyperplasia and only 2 studies reported the presence of granulomas. In addition, in XLA-associated enteritis, immunohistochemistry showed the absence or marked reduction in B cells and plasma cells.

CONCLUSIONS

An XLA-associated enteritis is a distinct pathological process that presents clinically in a manner similar to ileocolonic CD. It is important to evaluate for infectious diarrhea, which is common in XLA and can mimic IBD clinically. Complete multidisciplinary evaluation is, therefore, recommended for XLA patients with persistent gastrointestinal symptoms. Although more research is needed, therapeutic selection for XLA-associated enteritis is like that of IBD, and the possible risk of drug interactions and complications from increasing immunosuppression should be considered.

Bruton's tyrosine kinase regulates gut immune homeostasis through attenuating Th1 response

Inflammatory bowel disease (IBD) is driven by multiple genetic and environmental risk factors. Patients with mutations in Bruton’s tyrosine kinase (BTK) is known to manifest high prevalence of intestinal disorders including IBD. Although BTK mediates the signaling of various immune receptors, little is known how BTK maintains the homeostasis of the gut immune system. Here, we show that BTK-deficiency promotes IBD progression in a mouse model of colitis. Interestingly, the increased colitis susceptibility of BTK-deficient mice is not caused by gut microbiota changes but rather arises from enhanced pro-inflammatory Th1 response. More importantly, we find the heightened Th1 response in BTK-deficient mice to result from both T cell-extrinsic and -intrinsic mechanisms. BTK-deficient dendritic cells secret elevated levels of the Th1-polarizing cytokine IL-12 and BTK-deficient T cells are inherently more prone to Th1 differentiation. Thus, BTK plays critical roles in maintaining gut immune homeostasis and preventing inflammation via regulating T-cell polarization.

Current Spectrum of Infections in Patients with X-Linked Agammaglobulinemia

Outcome of patients with X-linked agammaglobulinemia (XLA) has improved with the widespread use of immunoglobulin replacement therapy (IgRT). There are few data on the spectrum of infections experienced by patients undergoing IgRT. We carried out a retrospective cross-sectional analysis of the records of XLA patients seen at Necker-Enfants Malades Hospital, Paris. For each infection, we evaluated infection site, microbial etiology, antibiotic prophylaxis, immunosuppressive treatment, IgRT route, and last known IgG trough level. Sixty patients were included, who cumulated a follow-up of 1470 patient-years. We recorded 188 infections, including 97 after initiation of IgRT. The rate of infection was highest before IgRT (0.66 vs. 0.06 per person-year (ppy), p < 0.001) and was higher after the age of 16 compared to before (0.14 vs. 0.05 ppy, p = 0.048). It was similar for patients receiving intravenous or subcutaneous Ig (0.09 vs 0.05 ppy, p = 0.54). The lungs and gastrointestinal tract accounted for 71% of infection sites. Forty-six (47%) infections occurred in patients receiving antibiotic prophylaxis. Sixteen (16.5%) infections occurred in patients receiving immunosuppressive therapy, which more frequently occurred after age 16 (35% vs. 2.4%, p < 0.001). The median IgG trough level prior to all infections was 8.4 g/L. Almost half (44.3%) of infections occurred with prior IgG trough levels > 8 g/L, and 16/97 (16.7%) in patients with trough levels > 10 g/L. Infection remains a significant issue in patients with XLA undergoing IgRT despite adequate IgG trough levels. Chronic inflammatory manifestations of X-linked agammaglobulinemia and immunosuppressive therapies may be significant drivers of infection during adulthood.

Inborn Errors of Immunity and Cancer

Simple Summary

Inborn Errors of Immunity (IEI) are a heterogeneous group of disorders characterized by a defect in the function of at least one, and often more, components of the immune system. The overall risk for cancer in children with IEI ranges from 4 to 25%. Several factors, namely, age of the patient, viral infection status and IEI type can influence the development of different cancer types. Immunologists and oncologists should interact to monitor and promptly diagnose the potential development of cancer in known IEI patients, as well as an underlying IEI in newly diagnosed cancers with suggestive medical history or high rate of therapy-related toxicity. The creation of an international registry of IEI cases with detailed information on the occurrence of cancer is fundamental to optimizing the diagnostic process and to evaluating the outcomes of new therapeutic options, with the aim of improving prognosis and reducing comorbidities.

Abstract

Inborn Errors of Immunity (IEI) are a heterogeneous group of disorders characterized by a defect in the function of at least one, and often more, components of the immune system. The aim of this narrative review is to discuss the epidemiology, the pathogenesis and the correct management of tumours in patients with IEI. PubMed was used to search for all of the studies published over the last 20 years using the keywords: “inborn errors of immunity” or “primary immunodeficiency” and “cancer” or “tumour” or “malignancy”. Literature analysis showed that the overall risk for cancer in children with IEI ranges from 4 to 25%. Several factors, namely, age of the patient, viral infection status and IEI type can influence the development of different cancer types. The knowledge of a specific tumour risk in the presence of IEI highlights the importance of a synergistic effort by immunologists and oncologists in tracking down the potential development of cancer in known IEI patients, as well as an underlying IEI in patients with newly diagnosed cancers. In the current genomic era, the creation of an international registry of IEI cases integrated with malignancies occurrence information is fundamental to optimizing the diagnostic process and to evaluating the outcomes of new therapeutic options, with the hope to obtain a better prognosis for these patients.

Inflammasome Regulation: Therapeutic Potential for Inflammatory Bowel Disease

Inflammasomes are multiprotein complexes formed to regulate the maturation of pro-inflammatory caspases, in response to intracellular or extracellular stimulants. Accumulating studies showed that the inflammasomes are implicated in the pathogenesis of inflammatory bowel disease (IBD), although their activation is not a decisive factor for the development of IBD. Inflammasomes and related cytokines play an important role in the maintenance of gut immune homeostasis, while its overactivation might induce excess immune responses and consequently cause tissue damage in the gut. Emerging studies provide evidence that some genetic abnormalities might induce enhanced NLRP3 inflammasome activation and cause colitis. In these cases, the colonic inflammation can be ameliorated by blocking NLRP3 activation or its downstream cytokine IL-1β. A number of natural products were shown to play a role in preventing colon inflammation in various experimental colitis models. On the other hand, lack of inflammasome function also causes intestinal abnormalities. Thus, an appropriate regulation of inflammasomes might be a promising therapeutic strategy for IBD intervention. This review aims at summarizing the main findings in these studies and provide an outline for further studies that might contribute to our understanding of the role of inflammasomes in the pathogenesis and therapeutic treatment of IBD.

Human Inborn Errors of Immunity (HIEI): predominantly antibody deficiencies (PADs): if you suspect it, you can detect it

OBJECTIVE

This minireview gathers the scientific foundations of the literature on genetic errors in the development of the humoral immune system to help pediatricians suspect these defects.

SOURCES

A systemic search using the PubMed MEDLINE database was performed for all Predominantly Antibody Deficiencies (PADs) described in the 2020 IUIS Expert Committee for PID classification system, combined with terms for hypogammaglobulinemia. Search terms for PADs were based on the listed names and affected genes as classified by the IUIS 2020. Abstracts of the results were reviewed to find relevant case series, review articles of PADs associated with infection, opportunistic infection, autoimmunity, cytopenias, malignancies, inflammatory diseases, neurological and respiratory diseases. References from relevant articles were further reviewed for additional references. Relevant findings were grouped in accordance with the IUIS 2020 classification system. Clinical and genetic features, if known, were described.

DATA SYNTHESIS

PADs refer to impaired antibody production due to molecular defects intrinsic to B cells or a failure of interaction between B and T cells. The patients develop recurrent or chronic infection or respond to the antigens with dysregulation of the immune function, causing severe allergy, autoimmunity, inflammation, lymphoproliferation and malignancy. The diagnosis is a combined exercise of clinical and laboratory investigation similar to that performed by Bruton (1952). In the context of SARS-CoV-2 infection, the experience of XLA and CVID patients has been surprising. Variants in 39 genes were reported as causing PADs, but the clinical heterogeneity within each variant is not clear.

CONCLUSION

Bruton (1952) used clinical expertise and protein electrophoresis to identify XLA. The IUIS (2020) committee used immunoglobulins and B lymphocyte to characterize PADs. Pediatricians should suspect it to detect it and prevent morbidities that can have an astonishing and irreversible impact on the child's life.

Bruton tyrosine kinase deficiency augments NLRP3 inflammasome activation and causes IL-1β-mediated colitis

Bruton tyrosine kinase (BTK) is present in a wide variety of cells and may thus have important non-B cell functions. Here, we explored the function of this kinase in macrophages with studies of its regulation of the NLR family, pyrin domain-containing 3 (NLRP3) inflammasome. We found that bone marrow-derived macrophages (BMDMs) from BTK-deficient mice or monocytes from patients with X-linked agammaglobulinemia (XLA) exhibited increased NLRP3 inflammasome activity; this was also the case for BMDMs exposed to low doses of BTK inhibitors such as ibrutinib and for monocytes from patients with chronic lymphocytic leukemia being treated with ibrutinib. In mechanistic studies, we found that BTK bound to NLRP3 during the priming phase of inflammasome activation and, in doing so, inhibited LPS- and nigericin-induced assembly of the NLRP3 inflammasome during the activation phase of inflammasome activation. This inhibitory effect was caused by BTK inhibition of protein phosphatase 2A-mediated (PP2A-mediated) dephosphorylation of Ser5 in the pyrin domain of NLRP3. Finally, we show that BTK-deficient mice were subject to severe experimental colitis and that such colitis was normalized by administration of anti-IL-β or anakinra, an inhibitor of IL-1β signaling. Together, these studies strongly suggest that BTK functions as a physiologic inhibitor of NLRP3 inflammasome activation and explain why patients with XLA are prone to develop Crohn's disease.

The Importance of Primary Immune Deficiency Registries: The United States Immunodeficiency Network Registry

The importance of registries is vital for almost every human disease but crucial for rare disorders, where the centralized collection, organization, and quality check of data create a platform from where multiple analyses and scientific advances are possible. In this article, the authors review the creation of the United States Immunodeficiency Network registry, its role, and the numerous scientific achievements generated from the collective effort of many.

Evaluation of respiratory complications in patients with X-linked and autosomal recessive agammaglobulinemia

BACKGROUND

Congenital agammaglobulinemia is the first primary immunodeficiency disorder characterized by a defect in B lymphocyte development and subsequently decreased immunoglobulin levels. These patients are prone to suffer from recurrent infections mostly involving the respiratory tract. In this study, we aimed to describe in detail respiratory tract complications as the most prominent clinical feature among agammaglobulinemic patients.

METHODS

A total number of 115 patients were included. Demographic, clinical, and genetic data were collected from the patients' medical records. Among the available patients, pulmonary function tests (PFTs) and/or high-resolution computed tomography (HRCT) were performed.

RESULTS

Respiratory tract complications (85.2%) especially pneumonia (62.6%) were the most prominent clinical features in our cohort. Among patients with abnormal PFT results (N = 19), a mixed respiratory pattern was observed in 36.8%. HRCT was carried out in 29 patients; Bhalla scoring-based evaluation of these patients indicated excellent (44.8%), followed by good (34.5%) and mild (20.7%) results. Bronchiectasis was found in 13 patients undergoing HRCT (44.8%). We found significant inverse correlations between the Bhalla score and incidence rate of pneumonia, as well as the presence of bronchiectasis. Patients with abnormal PFT results had statistically significant higher bronchiectasis frequency and lower Bhalla scores compared to those with normal results. Forty-one patients were deceased, and here, respiratory failure was the most common cause of death (45.5%).

CONCLUSION

High prevalence of respiratory tract infections among agammaglobulinemic patients and subsequent progression to permanent lung damage highlights the importance of implementing respiratory evaluation as part of routine follow-up program of agammaglobulinemic patients. Physicians should be aware of this and regularly monitor the respiratory function of these patients to allow for timely diagnosis and treatment initiation aiming to improve patients' prognosis and quality of life.

Gene analysis of seven cases of primary immunodeficiency

BACKGROUND

Primary immune deficiency diseases (PID) are a group of potentially serious disorders in which inherited defects in the immune system lead to increased infections. This paper explores the clinical characteristics and pathogenic gene mutation of PID.

METHODS

The clinical data, clinical manifestations, and gene sequencing results of seven children were analyzed.

RESULTS

Among the seven children, six were male, and one was female, aged from 4 months to 13 years old. All of them had a history of repeated infection and pneumonia. High throughput sequencing (NGS) showed that the BTK gene of case 1 had c.1921c > t mutation; the BTK gene of case 2 had c.906-908del splice site mutation; the BTK gene of case 3 had c.718delg mutation; the cybb gene of case 4 had c.469c > t mutation; the IL2RG gene of case 5 had c.202g > A mutation; the STAT1 gene of case 6 had c.854a > G mutation; the case 7 had c.718delg mutation. There was c.1154c > t mutation in the STAT1 gene. Cases 1, 3, 6 and 7 were new mutations, and cases 2, 4, and 5 were inherited from mothers.

CONCLUSIONS

In clinical cases of children with recurrent infection, the immunologic index is abnormal, so we need to be highly aware of the possibility of PID, and timely high-throughput sequencing is helpful for the diagnosis.

Long-term follow-up of 168 patients with X-linked agammaglobulinemia reveals increased morbidity and mortality

BACKGROUND

X-linked agammaglobulinemia (XLA) is the prototype of primary humoral immunodeficiencies. Long-term follow-up studies regarding disease-related complications and outcome are scarce.

OBJECTIVE

Our aim was to describe the natural history of XLA.

METHODS

A nationwide multicenter study based on the Italian Primary Immunodeficiency Network registry was established in 2000 in Italy. Affected patients were enrolled by documenting centers, and the patients' laboratory, clinical, and imaging data were recorded on an annual base.

RESULTS

Data on the patients (N = 168) were derived from a cumulative follow-up of 1370 patient-years, with a mean follow-up of 8.35 years per patient. The mean age at diagnosis decreased after establishment of the Italian Primary Immunodeficiency Network registry (84 months before vs 23 months after). Respiratory, skin, and gastrointestinal manifestations were the most frequent clinical symptoms at diagnosis and during long-term follow-up. Regular immunoglobulin replacement treatment reduced the incidence of invasive infections. Affected patients developed chronic lung disease over time (47% after 40 years of follow-up) in the presence of chronic sinusitis (84%). Malignancies were documented in a minority of cases (3.7%). Overall survival for affected patients was significantly reduced when compared with that for the healthy male Italian population, and it further deteriorated in the presence of chronic lung disease.

CONCLUSIONS

This is the first detailed long-term follow-up study for patients with XLA, revealing that although immunoglobulin replacement treatment reduces the incidence of invasive infections, it does not appear to influence the development of chronic lung disease. The overall survival of affected patients is reduced. Further studies are warranted to improve patients' clinical management and increase awareness among physicians.

Gastrointestinal Disorders Associated with Primary Immunodeficiency Diseases

There are now 354 inborn errors of immunity (primary immunodeficiency diseases (PIDDs)) with 344 distinct molecular etiologies reported according to the International Union of Immunological Sciences (IUIS) (Clin Gastroenterol Hepatol 11: p. 1050-63, 2013, Semin Gastrointest Dis 8: p. 22-32, 1997, J Clin Immunol 38: p. 96-128, 2018). Using the IUIS document as a reference and cross-checking PubMed ( www.ncbi.nlm.nih.pubmed.gov ), we found that approximately one third of the 354 diseases of impaired immunity have a gastrointestinal component [J Clin Immunol 38: p. 96-128, 2018]. Often, the gastrointestinal symptomatology and pathology is the heralding sign of a PIDD; therefore, it is important to recognize patterns of disease which may manifest along the gastrointestinal tract as a more global derangement of immune function. As such, holistic consideration of immunity is warranted in patients with clinically significant gastrointestinal disease. Here, we discuss the manifold presentations and GI-specific complications of PIDDs which could lead patients to seek advice from a variety of clinician specialists. Often, patients with these medical problems will engage general pediatricians, surgeons, gastroenterologists, rheumatologists, and clinical immunologists among others. Following delineation of the presenting concern, accurate and often molecular diagnosis is imperative and a multi-disciplinary approach warranted for optimal management. In this review, we will summarize the current state of understanding of PIDD gastrointestinal disease involvement. We will do so by focusing upon gastrointestinal disease categories (i.e., inflammatory, diarrhea, nodular lymphoid hyperplasia, liver/biliary tract, structural disease, and oncologic disease) with an intent to aid the healthcare provider who may encounter a patient with an as-yet undiagnosed PIDD who presents initially with a gastrointestinal symptom, sign, or problem.

Infection by Leishmania (Leishmania) infantum chagasi causes intestinal changes B-1 cells dependent

Evaluating the histopathological and morphometric changes caused by Leishmania (Leishmania) infantum chagasi infection either in the presence or absence of B-1 cells. Wild-type Balb/c and XID mice were used. Half of XID mice received B-1 cells adoptive transfer (XID + B1). Five animals from each group were infected (Balb/c I, XID I and XID + B1 I), totalizing six groups (n = 5). After 45 days of infection, the ileum was collected for histological processing and analysis. After infection, the XID animals showed an increase in the thickness of the intestinal layers, in the depth and width of the crypt and in the villi width. However, the Balb/c I group showed a reduction in almost all these parameters, whereas the villi width was increased. The villi height decreased in the infected XID animals; however, it was increased in the XID + B1 I group. Leishmania (L) infantum chagasiinfection caused a decrease in the number of Paneth cells; however, their area was increased. Finally, goblet cells and enterocytes presented different change profiles among groups. This study showed that the parasite infection causes structural and histopathological alterations in the intestine. These changes might be influenced by the absence of B-1 cells.

Treosulfan-based reduced toxicity hematopoietic stem cell transplantation in X-linked agammaglobulinemia: A cost-effective alternative to long-term immunoglobulin replacement in developing countries

X-linked agammaglobulinemia (XLA) is a primary antibody disorder due to a mutation in the Bruton tyrosine kinase gene that requires lifelong immunoglobulin replacement resulting in a significant economic burden and treatment abandonment. Hematopoietic stem cell transplantation (HSCT) offers an alternative option for complete cure. In our series, two children with XLA underwent successful HSCT using a myeloablative conditioning with thiotepa, treosulfan, and fludarabine from a matched sibling donor. The second child had rejected his first graft following a busulfan-based regimen with resultant autologous reconstitution. At 6 months post-HSCT, serum IgG were normal, off IVIG, and had no infections. Both children after a median follow-up of 20 months have 100% chimerism. Treosulfan-based reduced toxicity myeloablative HSCT has encouraging results with a positive impact on the socioeconomics in developing countries.

Gastrointestinal Manifestations and Complications of Primary Immunodeficiency Disorders

Gastrointestinal (GI) involvement can be the presenting disease manifestation in patients with primary immunodeficiency disorders (PIDs). Infections and noninfectious diarrhea are frequent manifestations; however, malignancy and inflammatory and autoimmune-related GI diseases are also described. GI symptoms and disease seen in association with PIDs can mimic other diseases but are often resistant to conventional treatments owing to alternate disease mechanisms. Despite the advances in treatments for these conditions, therapy for immunodeficiency-related GI disease is often empiric.

Laboratory Assays of Immune Cell Function in Immunodeficiencies

Laboratory assays of immune cell function are essential for understanding the type and function of immune defects. These assessments should be performed in conjunction with a detailed history and physical examination, which should guide the evaluation of patients with a suspected immune deficiency. Laboratory assays of immune cell function are critical for assessing and demonstrating the functional impact of genetic mutations. Advances in diagnostic techniques continue to expand the ability of clinicians and researchers to understand the complex immune pathophysiology that underlies these disorders.

Approach to primary immunodeficiency

Primary immunodeficiency diseases are inherited defects of the innate or adaptive arms of the immune system that lead to an increase in the incidence, frequency, or severity of infections and/or immune dysregulation. There may be defects in the adaptive arm of the immune system, including combined immunodeficiencies and antibody deficiency syndromes, or abnormalities in innate immunity, such as defects of phagocytes, the complement pathway, or toll-like receptor mediated signaling. Recurrent sinopulmonary infections with encapsulated bacteria such as Haemophilus influenzae type B or Streptococcus pneumoniae may be characteristic of an antibody deficiency syndrome. Frequent viral, fungal, or protozoal infections may suggest T lymphocyte impairment. Multiple Staphylococcus skin infections and fungal infections may imply neutrophil dysfunction or the Hyper-IgE syndrome, and recurrent Neisseria infection is a characteristic manifestation of late complement component (C5-9, or the membrane attack complex) defects. Recurrent viral or pyogenic bacterial infections, often without the presence of a significant inflammatory response, suggest a defect in toll-like receptor signaling. Mycobacterial infections are characteristic of defects in the interleukin (IL) 12/interferon γ pathway. Screening of newborns for T-cell lymphopenia by using polymerase chain reaction to amplify T-cell receptor excision circles, which are formed when a T cell rearranges the variable region of its receptor, serves as a surrogate for newly synthesized naive T cells. Because of very low numbers of T-cell receptor excision circles, severe combined immunodeficiency, 22q11.2 syndrome, and other causes of T-cell lymphopenia have been identified in newborns.

Primary Immunodeficiency and the Gut

This article presents the most common gastrointestinal, hepatic, and pancreatic manifestations of the primary immunodeficiency diseases, including the appropriate laboratory testing, endoscopic evaluation, and recommendations for further management.

Primary immunodeficiency and autoimmunity: A comprehensive review

The primary immunodeficiency diseases (PIDs) include many genetic disorders that affect different components of the innate and adaptive responses. The number of distinct genetic PIDs has increased exponentially with improved methods of detection and advanced laboratory methodology. Patients with PIDs have an increased susceptibility to infectious diseases and non-infectious complications including allergies, malignancies and autoimmune diseases (ADs), the latter being the first manifestation of PIDs in several cases. There are two types of PIDS. Monogenic immunodeficiencies due to mutations in genes involved in immunological tolerance that increase the predisposition to develop autoimmunity including polyautoimmunity, and polygenic immunodeficiencies characterized by a heterogeneous clinical presentation that can be explained by a complex pathophysiology and which may have a multifactorial etiology. The high prevalence of ADs in PIDs demonstrates the intricate relationships between the mechanisms of these two conditions. Defects in central and peripheral tolerance, including mutations in AIRE and T regulatory cells respectively, are thought to be crucial in the development of ADs in these patients. In fact, pathology that leads to PID often also impacts the Treg/Th17 balance that may ease the appearance of a proinflammatory environment, increasing the odds for the development of autoimmunity. Furthermore, the influence of chronic and recurrent infections through molecular mimicry, bystander activation and super antigens activation are supposed to be pivotal for the development of autoimmunity. These multiple mechanisms are associated with diverse clinical subphenotypes that hinders an accurate diagnosis in clinical settings, and in some cases, may delay the selection of suitable pharmacological therapies. Herein, a comprehensively appraisal of the common mechanisms among these conditions, together with clinical pearls for treatment and diagnosis is presented.

A Tumor Profile in Primary Immune Deficiencies Challenges the Cancer Immune Surveillance Concept

Under the concept of cancer immune surveillance, individuals with primary immune deficiencies would be expected to develop many more malignancies and show an excess of all types of cancers, compared to people with a normal immune system. A review of the nine most frequent and best-documented human conditions with primary immune deficiency reveals a 1.6- to 2.3-fold global increase of cancer in the largest epidemiological studies. However, the spectrum of cancer types with higher frequencies is narrow, limited mainly to lymphoma, digestive tract cancers, and virus-induced cancers. Increased lymphoma is also reported in animal models of immune deficiency. Overstimulation of leukocytes, chronic inflammation, and viruses explain this tumor profile. This raises the question of cancers being foreign organisms or tissues. Organisms, such as bacteria, viruses, and parasites as well as non-compatible grafts are seen as foreign (non-self) and identified and destroyed or rejected by the body (self). As cancer cells rarely show strong (and unique) surface antibodies, their recognition and elimination by the immune system is theoretically questionable, challenging the immune surveillance concept. In the neonatal period, the immune system is weak, but spontaneous regression and good outcomes occur for some cancers, suggesting that non-immune factors are effective in controlling cancer. The idea of cancer as a group of cells that must be destroyed and eliminated appears instead as a legacy of methods and paradigms in microbiological medicine. As an alternative approach, cancer cells could be considered part of the body and could be controlled by an embryonic and neonatal environment.

IgM Augments Complement Bactericidal Activity with Serum from a Patient with a Novel CD79a Mutation

Antibody replacement therapy for patients with antibody deficiencies contains only IgG. As a result, concurrent IgM and IgA deficiency present in a large proportion of antibody deficient patients persists. Especially patients with IgM deficiency remain at risk for recurrent infections of the gastrointestinal and respiratory tract. The lack of IgM in the current IgG replacement therapy is likely to contribute to the persistence of these mucosal infections because this antibody class is especially important for complement activation on the mucosal surface. We evaluated whether supplementation with IgM increased serum bactericidal capacity in vitro. Serum was collected from a patient with agammaglobulinemia and supplemented with purified serum IgM to normal levels. Antibody and complement deposition on the bacterial surface was determined by multi-color flow cytometry. Bacterial survival in serum was determined by colony-forming unit counts. We present a patient previously diagnosed with agammaglobulinemia due to CD79A (Igα) deficiency revealing a novel pathogenic insertion variant in the CD79a gene (NM_001783.3:c.353_354insT). Despite IgG replacement therapy and antibiotic prophylaxis, this patient developed a Campylobacter jejuni spondylodiscitis of lumbar vertebrae L4–L5. We found that serum IgM significantly contributes to complement activation on the bacterial surface of C. jejuni. Furthermore, supplementation of serum IgM augmented serum bactericidal activity significantly. In conclusion, supplementation of intravenous IgG replacement therapy with IgM may potentially offer greater protection against bacterial infections, also in the context of increasing antibiotic resistance.

Recurrent and Sustained Viral Infections in Primary Immunodeficiencies

Viral infections are commonplace and often innocuous. Nevertheless, within the population of patients with primary immunodeficiencies (PIDDs), viral infections can be the feature that drives a diagnostic evaluation or can be the most significant morbidity for the patient. This review is focused on the viral complications of PIDDs. It will focus on respiratory viruses, the most common type of viral infection in the general population. Children and adults with an increased frequency or severity of respiratory viral infections are often referred for an immunologic evaluation. The classic teaching is to investigate humoral function in people with recurrent sinopulmonary infections, but this is often interpreted to mean recurrent bacterial infections. Recurrent or very severe viral infections may also be a harbinger of a primary immunodeficiency as well. This review will also cover persistent cutaneous viral infections, systemic infections, central nervous system infections, and gastrointestinal infections. In each case, the specific viral infections may drive a diagnostic evaluation that is specific for that type of virus. This review also discusses the management of these infections, which can become problematic in patients with PIDDs.