Characterization of immunologic defects in patients with common variable immunodeficiency (CVID) with intestinal disease

The Histologic Spectrum of Rituximab-Associated Common Variable Immunodeficiency-Like Enteropathy

Rituximab (RTX) is a monoclonal anti-CD20 antibody widely used to treat B-cell neoplasms and autoimmune conditions. RTX has recently been linked to an enteropathy characterized by diarrhea, malabsorption, and hypogammaglobulinemia, closely resembling common variable immunodeficiency (CVID) enteropathy. We present the first dedicated histopathologic assessment of RTX-associated CVID-like enteropathy. Study inclusion criteria were the presence of diarrhea, weight loss, or other gastrointestinal symptoms in the setting of current/prior RTX use and associated hypogammaglobulinemia. Twenty-two patients (15 male:7 female; mean age at biopsy/resection, 63.4 years) across 9 tertiary medical centers met inclusion criteria and had small bowel (N = 20) and/or colon (N = 17) specimens (biopsies/resections) available for review; 71.4% of specimens dated from ≤5 years of last RTX dose. Cases were systematically evaluated by gastrointestinal pathologists at each institution. Key histologic features in the small bowel included sparse/absent lamina propria plasma cells (N = 10; 50%), intraepithelial lymphocytosis (N = 12; 60%), villous atrophy (N = 11; 55%), increased crypt apoptotic bodies (N = 6; 30%), and active inflammation (N = 5; 25%). Common features in the colon included sparse/absent plasma cells (N = 7; 41.2%), increased crypt apoptotic bodies (N = 7; 41.2%), active inflammation (N = 5; 29.4%), and intraepithelial lymphocytosis (N = 4; 23.5%). Goblet cell loss was appreciated in small bowel and/or colon specimens from 2 patients. Follow-up biopsies (interval, 2 months to 4 years) were available for 7 patients and largely recapitulated the histology of the index specimens, though 1 patient demonstrated improvement in villous blunting and intraepithelial lymphocytosis. In summary, the histologic spectrum of post-RTX CVID-like enteropathy encompasses lamina propria plasma cell depletion, increased crypt apoptotic bodies, small bowel villous atrophy, and goblet cell loss. While the underlying pathophysiology remains uncertain, the clinicopathologic picture may reflect post-RTX B-cell/plasma cell impairment. Although histologic findings may be subtle and variable, pathologists should be aware of this entity and should seek a history of RTX use in patients whose biopsies exhibit these CVID enteropathy-like features.

Gastrointestinal pathology in Good's syndrome, thinking beyond common variable immunodeficiency: a clinicopathological observation

Good's syndrome (GS) is a rare immunodeficiency associated with thymoma, characterized by increased susceptibility to bacterial, viral, and fungal infections, along with autoimmune manifestations. Gastrointestinal symptoms are common in GS, yet its clinical and histopathological features remain underrecognized. Due to significant overlap in clinical presentation and immunological profiles, GS is frequently misdiagnosed as common variable immunodeficiency (CVID). While gastrointestinal pathology in CVID has been well-documented, data on gastrointestinal manifestations in GS are limited. In this study, we analyzed two cases of GS, both demonstrating marked reduction of plasma cells across multiple gastrointestinal sites, with variable intraepithelial lymphocytosis and mild to moderate villous blunting in the duodenum and features secondary to chronic norovirus infection in one case, and an invasive adenocarcinoma with notable depletion of lamina propria plasma cells in the other. Accurate recognition of GS is essential for pathologists and clinicians, given its poorer prognosis compared to CVID.

Gastrointestinal Disease in Common Variable Immunodeficiency Disorder (CVID): Histological Patterns, Diagnostic Clues and Pitfalls for the Pathologist and Gastroenterologist

Background/Objectives: Gastrointestinal diseases are a major cause of morbidity in common variable immunodeficiency disorder (CVID), clinically often mimicking other conditions including celiac disease and inflammatory bowel disease (IBD). Hence, diagnosis of CVID remains challenging. This study aims to raise awareness and highlight histopathological clues for CVID in intestinal biopsies, emphasizing diagnostic pitfalls for the pathologist/gastroenterologist. Methods: We reviewed 63 (18 duodenal, 23 ileal, 22 colonic) biopsies and case histories from seven CVID patients, obtained over a 31-year period, with attention to active inflammation, intraepithelial lymphocytes, plasma cells, lymphoid hyperplasia, crypt/villous architecture, subepithelial collagen, apoptosis, granulomas, and infections. Clinical information of 41 pathology requests was reviewed. Results: Gastrointestinal symptoms were variable. Histological features included IBD-like (3/7), celiac disease-like (2/7), graft-versus-host disease (GVHD)-like (2/7), lymphocytic sprue/colitis-like (3/7), collagenous colitis-like (2/7), and acute colitis-like (4/7) patterns, often overlapping (2/7) and/or changing over time (3/7). Lymphoid hyperplasia was seen in 3/7 patients; 1/7 had giardiasis; and 5/7 had few plasma cells, usually only in part of the gut (3/5). Clinical information of 12/41 (29%) pathology requests mentioned known/suspected CVID, despite being known in 33/41 (80%). Conclusions: Clinical/histological features of CVID in the gut are diverse, often mimicking IBD, microscopic colitis, celiac disease and/or GVHD, hence the importance of adequate clinical information. Some histological features are atypical of these established entities and may indicate CVID, as may overlapping/changing histological patterns and/or few plasma cells in part of the gut. Awareness of the heterogenous clinical presentation and histopathological indicators of CVID may improve diagnosis.

The Natural History of Inflammatory Bowel Disease in Adults With Common Variable Immunodeficiency: A Case Series From a Single US Tertiary Care Center

Background

Common variable immunodeficiency (CVID) predisposes patients to inflammatory bowel disease (IBD). There are limited studies characterizing adults with concomitant CVID and IBD (CVID-IBD).

Methods

Demographics, clinical courses, endoscopic findings, and disease-specific therapies were obtained in adults ≥18 years with CVID-IBD over a 5-year period.

Results

We identified 11 patients with CVID-IBD, 6 with Crohn's disease (CD), and 5 with ulcerative colitis (UC). The presenting symptoms in 10 (91%) were abdominal pain and diarrhea. A majority of patients were diagnosed with IBD before CVID. Patients with CVID-IBD were diagnosed with CVID at an older age compared to patients with CVID only. The most prevalent endoscopic finding in CD was either erythema or erosions in the ileum, whereas in UC, it was pancolitis. One patient with CD and 1 with UC required treatment with immunomodulators to achieve remission. Three patients with CD and 2 with UC required treatment with biologics to achieve remission. Eight received intravenous immunoglobulin (IVIG) for CVID. Four patients with CD and 1 with UC were diagnosed with either leukemia or lymphoma, and the most common malignancy was chronic lymphocytic leukemia (n = 3).

Conclusions

This is one of few studies evaluating demographic, clinical, endoscopic, histologic features, and therapeutic management in patients with CVID-IBD. Further studies are required to elucidate long-term differences in the clinical course and treatment of patients with CVID-IBD.

Paucity of gastrointestinal plasma cells in common variable immunodeficiency

PURPOSE OF REVIEW

Common variable immunodeficiency enteropathy (CVID-E) is a noninfectious complication of CVID caused by chronic inflammation of the gastrointestinal (GI) tract. Based on literature, a paucity or lack of plasma cells, although not obligatory for diagnosis, is a pathognomonic feature of CVID and more frequent in CVID-E. However, there is no consensus on standardized histopathological analysis of this feature in biopsies. In this systematic review, we highlight methods of reproducible plasma cell quantification of biopsies in CVID and describe the plasma cell counts and classes as presented in the literature.

RECENT FINDINGS

Reduced plasma cell counts are commonly found over the entire GI tract, except for in the oesophagus. Immunoglobulin A+ (IgA+) plasma cells appear to be the most commonly reduced plasma cell class in CVID, yet there is scarce literature on the predictive value of low IgA+ plasma cell counts in CVID-E.

SUMMARY

We propose two optimized methodologies of quantification using a cut-of value of <10 plasma cells per HPF at 40× magnification, or a proportion of ≥1-5% of total mononuclear cells, recorded over ≥3 sections, and in ≥2 biopsies, as the most conservative agreeable definitions for a paucity of plasma cells to be used in diagnostics and further research.

Congenital Diarrhoeas and Enteropathies

Congenital diarrhoeas and enteropathies (CODE) are a heterogeneous group of disorders. Many affected infants present with catastrophic dehydration in the first few days of life, although the clinical phenotype is variable. Advances in the understanding of underlying pathomechanisms and genetic testing, as well as improved management, in particular intravenous nutrition support, have allowed affected patients to survive well beyond childhood. Awareness and understanding of these rare diseases are hence needed, both amongst paediatricians and adult physicians. In this review, we discuss the different groups of disorders based on a review of the current literature and provide a diagnostic and therapeutic approach. Many of the subtypes of CODE result in the need for prolonged or indefinite parenteral nutrition. Further research is needed to identify new CODE to improve the recognition and management of these children, which can assist in developing new targeted therapies and potentially a long-term cure.

The autoimmune rheumatological presentation of Common Variable Immunodeficiency Disorders with an overview of genetic testing

Primary immunodeficiency Disorders (PIDS) are rare, mostly monogenetic conditions which can present to a number of specialties. Although infections predominate in most PIDs, some individuals can manifest autoimmune or inflammatory sequelae as their initial clinical presentation. Identifying patients with PIDs can be challenging, as some can present later in life. This is often seen in patients with Common Variable Immunodeficiency Disorders (CVID), where symptoms can begin in the sixth or even seventh decades of life. Some patients with PIDs including CVID can initially present to rheumatologists with autoimmune musculoskeletal manifestations. It is imperative for these patients to be identified promptly as immunosuppression could lead to life-threatening opportunistic infections in these immunocompromised individuals. These risks could be mitigated by prior treatment with subcutaneous or intravenous (SCIG/IVIG) immunoglobulin replacement or prophylactic antibiotics. Importantly, many of these disorders have an underlying genetic defect. Individualized treatments may be available for the specific mutation, which may obviate or mitigate the need for hazardous broad-spectrum immunosuppression. Identification of the genetic defect has profound implications not only for the patient but also for affected family members, who may be at risk of symptomatic disease following an environmental trigger such as a viral infection. Finally, there may be clinical clues to the underlying PID, such as recurrent infections, the early presentation of severe or multiple autoimmune disorders, as well as a relevant family history. Early referral to a clinical immunologist will facilitate appropriate diagnostic evaluation and institution of treatment such as SCIG/IVIG immunoglobulin replacement. This review comprises three sections; an overview of PIDs, focusing on CVID, secondly genetic testing of PIDs and finally the clinical presentation of these disorders to rheumatologists.

FDG-Avid Granulomatous Lymphocytic Interstitial Lung Disease With Common Variable Immunodeficiency

ABSTRACT

A 26-year-old woman with known common variable immunodeficiency was referred for FDG PET/CT because of interstitial pulmonary abnormalities and enlarged mediastinal and hilar lymph nodes. FDG PET showed a combination of ground-glass abnormalities and pulmonary nodules, both displaying increased FDG uptake. In addition, multiple FDG-avid axillary, mediastinal, hilar, and inguinal lymph nodes were found. The abnormalities were diagnosed as granulomatous-lymphocytic interstitial lung disease. Cytology of mediastinal lymph nodes yielded only benign disease, without further specification, whereas histology of an excised axillary lymph node showed reactive changes, but no malignancy.

Dysregulated Lymphocyte Antigen Receptor Signaling in Common Variable Immunodeficiency with Granulomatous Lymphocytic Interstitial Lung Disease

PURPOSE

A subset of common variable immunodeficiency (CVID) patients either presents with or develops autoimmune and lymphoproliferative complications, such as granulomatous lymphocytic interstitial lung disease (GLILD), a major cause of morbidity and mortality in CVID. While a myriad of phenotypic lymphocyte derangements has been associated with and described in GLILD, defects in T and B cell antigen receptor (TCR/BCR) signaling in CVID and CVID with GLILD (CVID/GLILD) remain undefined, hindering discovery of biomarkers for disease monitoring, prognostic prediction, and personalized medicine approaches.

METHODS

To identify perturbations of immune cell subsets and TCR/BCR signal transduction, we applied mass cytometry analysis to peripheral blood mononuclear cells (PBMCs) from healthy control participants (HC), CVID, and CVID/GLILD patients.

RESULTS

Patients with CVID, regardless of GLILD status, had increased frequency of HLADR+CD4+ T cells, CD57+CD8+ T cells, and CD21lo B cells when compared to healthy controls. Within these cellular populations in CVID/GLILD patients only, engagement of T or B cell antigen receptors resulted in discordant downstream signaling responses compared to CVID. In CVID/GLILD patients, CD21lo B cells showed perturbed BCR-mediated phospholipase C gamma and extracellular signal-regulated kinase activation, while HLADR+CD4+ T cells and CD57+CD8+ T cells displayed disrupted TCR-mediated activation of kinases most proximal to the receptor.

CONCLUSION

Both CVID and CVID/GLILD patients demonstrate an activated T and B cell phenotype compared to HC. However, only CVID/GLILD patients exhibit altered TCR/BCR signaling in the activated lymphocyte subsets. These findings contribute to our understanding of the mechanisms of immune dysregulation in CVID with GLILD.

Autoimmune disorders associated with common variable immunodeficiency: prediction, diagnosis, and treatment

INTRODUCTION

Common variable immunodeficiency (CVID) is the most common symptomatic primary immunodeficiency. Due to the wide spectrum of the CVID manifestations, the differential diagnosis becomes complicated, ends in a diagnostic delay and increased morbidity and mortality rates. Autoimmunity is one of the important complications associated with CVID. While immunoglobulin replacement therapy has considerably decreased the mortality rate in CVID patients, mainly infection-related mortality, other complications such as autoimmunity appeared prevalent and, in some cases, life threatening.

AREAS COVERED

In this article, genetics, responsible immune defects, autoimmune manifestations in different organs, and the diagnosis and treatment processes in CVID patients are reviewed, after searching the literature about these topics.

EXPERT OPINION

Considering the many phenotypes of CVID and the fact that it remained undiagnosed until older ages, it is important to include various manifestations of CVID in the differential diagnosis. Due to the different manifestations of CVID, including autoimmune diseases, interdisciplinary collaboration of physicians from different fields is highly recommended, as discussed in the manuscript. Meanwhile, it is important to determine which patients could benefit from genetic diagnostic studies since such studies are not necessary for establishing the diagnosis of CVID.

An Expert Opinion/Approach: Clinical Presentations, Diagnostic Considerations, and Therapeutic Options for Gastrointestinal Manifestations of Common Variable Immune Deficiency

Common variable immunodeficiency (CVID) is the most common symptomatic primary immunodeficiency. It is characterized by impaired B-cell differentiation. Although patients can be diagnosed with CVID anytime during their lifetime, most patients have symptoms for 5-9 years before their diagnosis. The diagnosis of CVID starts with a detailed history focusing on the infectious and noninfectious manifestations of the disease. In patients who are suspected to experience CVID, quantitative immunoglobulins (Ig) should be checked to confirm the diagnosis. IgG should be at least 2 times less than the age-specific SD along with either a low IgA or IgM and with evidence of impaired vaccine response. CVID is usually associated with infectious and/or noninfectious conditions, the latter of which can be inflammatory, autoimmune, lymphoproliferative, or malignant, among other manifestations. Ig therapy has positively affected the disease course of patients with infectious complications but has limited effect on the noninfectious manifestations because the noninfectious complications are related to immune dysregulation involving B cells and T cells rather than primarily due to antibody deficiency. When the gastrointestinal (GI) system is involved, patients with CVID may display signs and symptoms that mimic several GI conditions such as celiac disease, pernicious anemia, or inflammatory bowel diseases. The inflammatory bowel disease-like condition is usually treated with steroids, 5-aminosalicylates, thiopurines, or biologic agents to control the inflammation. In this review, the clinical presentations, diagnostic considerations, and therapeutic options for GI manifestations of CVID will be discussed to facilitate the individualized management of these often-complex patients.

Primary Hypogammaglobulinaemia with Inflammatory Bowel Disease-Like Features: An ECCO CONFER Multicentre Case Series

BACKGROUND

Hypogammaglobulinaemia is a disorder characterized by low serum immunoglobulin levels and a high prevalence of gastrointestinal manifestations. In some cases, clinical and endoscopic features are indistinguishable from those of inflammatory bowel disease [IBD].

METHODS

This was a multicentre case series performed as a part of the European Crohn's and Colitis Organisation [ECCO] Collaborative Network of Exceptionally Rare case reports [CONFER] project.

RESULTS

This report includes 27 patients with primary hypogammaglobulinaemia and IBD-like features: 20 males and seven females, median age 45.6 years (interquartile range [IQR] 35.2-59). Crohn's disease-like features were noted in 23 patients, and four patients had ulcerative colitis-like features. The diagnosis of hypogammaglobulinaemia preceded a diagnosis of IBD-like features in 20 patients [median of 7 years prior, IQR 2.6-20.6 years], and followed the appearance of IBD-like features in seven cases [median of 1 year after, IQR 0.45-5.6 years]. Hypogammaglobulinaemia aetiologies were common variable immunodeficiency [66.6%], agammaglobulinaemia [7.4%], selective IgA-deficiency [11.1%], Good's syndrome [7.4%], IgG subclass deficiency with IgA deficiency [3.7%] and hyper-IgM [3.7%]. In addition to antibiotics and intravenous immunoglobulin [IVIG] for hypogammaglobulinaemia, 12 patients received IBD-related treatment including 5-aminosalicylate agents [two patients], corticosteroids [one patient], thiopurines [three patients], anti-tumour necrosis factor [four patients] and vedolizumab [two patients]. By the end of the follow-up (44.5 months [IQR 18-81]), 21/27 [77%] patients were in clinical remission.

CONCLUSION

This case series describes IBD-like features in patients with hypogammaglobulinaemia. The diagnosis of IBD-like features mainly occurred after that of hypogammaglobulinaemia, with successful recovery in the majority of cases after appropriate treatment.

Multisystem Autoimmune Inflammatory Disease, Including Colitis, Due to Inborn Error of Immunity

Our understanding of inflammatory bowel disease is changing as we identify genetic variants associated with immune dysregulation. Inflammatory bowel disease undetermined, even when diagnosed in older children and adolescents, in the setting of multiple inflammatory and infectious diseases should raise the suspicion of complex immune dysregulation with a monogenic basis. We report a case of inflammatory bowel disease undetermined triggered by exposure to a nonsteroidal antiinflammatory drug in a 16-year-old girl with a background history of juvenile idiopathic arthritis, cytopenias, recurrent respiratory tract and middle ear infections, and esophageal candidiasis. Immunologic assessment included measurement of immunoglobulin levels, lymphocyte immunophenotyping, B-cell functional tests, and whole-exome sequencing. Laboratory investigation revealed defects of humoral immunity, including mild persistent hypogammaglobulinemia affecting all 3 isotypes and absent isohemagglutinins. Whole exome sequencing revealed a heterozygous TNFRSF13B (Tumor Necrosis Factor Receptor Superfamily Member 13B, or Transmembrane Activator and Calcium-modulating cyclophilin ligand Interactor, TACI) gene variant, which is associated with common variable immunodeficiency and the development of autoimmune diseases. In conclusion, a clinical history of recurrent infections, atypical histologic features of inflammatory bowel disease, additional autoimmune manifestations, and an inadequate response to conventional therapy should prompt the physician to refer to an immunologist with the query of inborn error of immunity. We report how extensive immune evaluation and genetic diagnosis can individualize care and facilitate a multidisciplinary team approach.

Bowel Histology of CVID Patients Reveals Distinct Patterns of Mucosal Inflammation

Diarrhea is the commonest gastrointestinal symptom in patients with common variable immunodeficiency (CVID). Different pathologies in patients' bowel biopsies have been described and links with infections have been demonstrated. The aim of this study was to analyze the bowel histology of CVID patients in the Royal-Free-Hospital (RFH) London CVID cohort. Ninety-five bowel histology samples from 44 adult CVID patients were reviewed and grouped by histological patterns. Reasons for endoscopy and possible causative infections were recorded. Lymphocyte phenotyping results were compared between patients with different histological features. There was no distinctive feature that occurred in most diarrhea patients. Out of 44 patients (95 biopsies), 38 lacked plasma cells. In 14 of 21 patients with nodular lymphoid hyperplasia (NLH), this was the only visible pathology. In two patients, an infection with Giardia lamblia was associated with NLH. An IBD-like picture was seen in two patients. A coeliac-like picture was found in six patients, four of these had norovirus. NLH as well as inflammation often occurred as single features. There was no difference in blood lymphocyte phenotyping results comparing groups of histological features. We suggest that bowel histology in CVID patients with abdominal symptoms falls into three major histological patterns: (i) a coeliac-like histology, (ii) IBD-like changes, and (iii) NLH. Most patients, but remarkably not all, lacked plasma cells. CVID patients with diarrhea may have an altered bowel histology due to poorly understood and likely diverse immune-mediated mechanisms, occasionally driven by infections.

Peripheral B Cell Deficiency and Predisposition to Viral Infections: The Paradigm of Immune Deficiencies

In the era of COVID-19, understanding how our immune system responds to viral infections is more pertinent than ever. Immunodeficiencies with very low or absent B cells offer a valuable model to study the role of humoral immunity against these types of infection. This review looks at the available evidence on viral infections in patients with B cell alymphocytosis, in particular those with X-linked agammaglobulinemia (XLA), Good’s syndrome, post monoclonal-antibody therapy and certain patients with Common Variable Immune Deficiency (CVID). Viral infections are not as infrequent as previously thought in these conditions and individuals with very low circulating B cells seem to be predisposed to an adverse outcome. Particularly in the case of SARS-CoV2 infection, mounting evidence suggests that peripheral B cell alymphocytosis is linked to a poor prognosis.

Primary hypoparathyroidism in a patient with common variable immunodeficiency associated enteropathy

Background. Common variable immunodeficiency (CVID) is a rare disease characterized by humoral immunodeficiency, often causing sinopulmonary and gastrointestinal infections, and may cause enteropathy in some patients, which leads to severe malnutrition and electrolyte deficiencies. Although many autoimmune diseases are seen with increased frequency in CVID patients, primary hypoparathyroidism is extremely rare.Case presentation. A 50-year-old man with CVID presented with diarrhea. The patient had complaints for 2 years and was cachectic. He had severe electrolyte and vitamin deficiencies that did not respond to oral treatment. The diarrhea causes such as celiac, inflammatory bowel diseases, and gastrointestinal infections were excluded and the endoscopy showed enteropathic changes in the duodenum and colon. Concomitant hypoparathyroidism was also detected in the patient with hypocalcemia despite adequate replacement.Conclusion. Parenteral therapy should be considered in the management of CVID enteropathy cases that do not respond to oral replacement. Although very rare, hypoparathyroidism should be considered in the differential diagnosis of CVID patients with treatment-resistant hypocalcemia.

Gut Microbiota-Host Interactions in Inborn Errors of Immunity

Inborn errors of immunity (IEI) are a group of disorders that are mostly caused by genetic mutations affecting immune host defense and immune regulation. Although IEI present with a wide spectrum of clinical features, in about one third of them various degrees of gastrointestinal (GI) involvement have been described and for some IEI the GI manifestations represent the main and peculiar clinical feature. The microbiome plays critical roles in the education and function of the host's innate and adaptive immune system, and imbalances in microbiota-immunity interactions can contribute to intestinal pathogenesis. Microbial dysbiosis combined to the impairment of immunosurveillance and immune dysfunction in IEI, may favor mucosal permeability and lead to inflammation. Here we review how immune homeostasis between commensals and the host is established in the gut, and how these mechanisms can be disrupted in the context of primary immunodeficiencies. Additionally, we highlight key aspects of the first studies on gut microbiome in patients affected by IEI and discuss how gut microbiome could be harnessed as a therapeutic approach in these diseases.

Perspective: Evolving Concepts in the Diagnosis and Understanding of Common Variable Immunodeficiency Disorders (CVID)

Common variable immunodeficiency disorders (CVID) are the most frequent symptomatic primary immune deficiency in adults. At this time, the causes of these conditions are unknown. Patients with CVID experience immune system failure consequent to late onset antibody failure. They have increased susceptibility to infections and are also at risk of severe autoimmune and inflammatory disorders as a result of immune dysregulation. An increasing number of monogenic causes as well as a digenic disorder have been described in patients with a CVID phenotype. If a causative mutation is identified, patients are removed from the umbrella diagnosis of CVID and are reclassified as having a CVID-like disorder, resulting from a specific mutation. In non-consanguineous populations, next-generation sequencing (NGS) identifies a genetic cause in approximately 25% of patients with a CVID phenotype. It is six years since we published our diagnostic criteria for CVID. There is ongoing debate about diagnostic criteria, the role of vaccine responses and genetic analysis in the diagnosis of CVID. There have been several recent studies, which have addressed some of these uncertainties. Here we review this new evidence from the perspective of our CVID diagnostic criteria and speculate on future approaches, which may assist in identifying and assessing this group of enigmatic disorders.

Evaluation of very early-onset inflammatory bowel disease

PURPOSE OF REVIEW

Very early-onset inflammatory bowel disease (VEO-IBD) is a rare presentation defined as onset of intestinal inflammation at the age of <6 years. Some of these young children develop IBD because of inherent defects in immune or epithelial cell function resulting from deleterious mutations in genes involved in mucosal homeostasis. Here, we provide an overview of the clinical, genetic and immunologic approach in patients with VEO-IBD.

RECENT FINDINGS

More than 50 different monogenic disorders directly causing IBD have been identified in the last decade; most of them present with unique clinical features in the first years of life. Such a diagnosis may facilitate the administration of targeted therapies and is important for genetic counseling. Nevertheless, a monogenic disorder is identified only in a minority of patients with VEO-IBD. Consequently, different demographic, clinical and histologic features should prompt a detailed genetic and immunologic workup in patients with IBD.

SUMMARY

A diagnosis of monogenic IBD can have a huge impact on patient's care, enabling in some cases to provide personalized therapies. Clinicians should be aware of unique features of such disorders, and complete a detailed genetic and immune workup in selected cases, even when disease manifests beyond a young age.

Consensus of the Italian Primary Immunodeficiency Network on transition management from pediatric to adult care in patients affected with childhood-onset inborn errors of immunity

Medical advances have dramatically improved the long-term prognosis of children and adolescents with inborn errors of immunity (IEIs). Transfer of the medical care of individuals with pediatric IEIs to adult facilities is also a complex task because of the large number of distinct disorders, which requires involvement of patients and both pediatric and adult care providers. To date, there is no consensus on the optimal pathway of the transitional care process and no specific data are available in the literature regarding patients with IEIs. We aimed to develop a consensus statement on the transition process to adult health care services for patients with IEIs. Physicians from major Italian Primary Immunodeficiency Network centers formulated and answered questions after examining the currently published literature on the transition from childhood to adulthood. The authors voted on each recommendation. The most frequent IEIs sharing common main clinical problems requiring full attention during the transitional phase were categorized into different groups of clinically related disorders. For each group of clinically related disorders, physicians from major Italian Primary Immunodeficiency Network institutions focused on selected clinical issues representing the clinical hallmark during early adulthood.

Gastrointestinal Disease in Patients with Common Variable Immunodeficiency: A Retrospective Observational Study

BACKGROUND

Gastrointestinal (GI) symptoms are common among patients with common variable immunodeficiency disorder (CVID) yet remain poorly understood.

AIMS

The aim of this study was to characterize the demographic, clinical, endoscopic and histologic features of patients with CVID and GI symptoms.

METHODS

We conducted a retrospective observational study of all patients with CVID at a large Canadian tertiary care centre between January 2000 and May 2018.

RESULTS

We included 95 patients with CVID. The mean age of patients at the time of CVID diagnosis was 38.2(±16.0). Fifty-three (56%) patients were female. Sixty-four (67%) patients had GI symptoms, with a mean age of onset for GI symptoms of 43.4(±15.1) years. The most common symptoms were bowel movement changes (n = 55 [58%]) and abdominal pain (n = 44 [46%]). Patients with GI symptoms were more likely to have anemia (n = 23 [36%] versus n = 3 [10%], P = 0.0129), iron deficiency (n = 16 [25%] versus n = 2 [7%], P = 0.0481), and have received GI antibiotics (n = 37 [58%] versus n = 0, P < 0.0001) and proton pump inhibitors for reflux (n = 24 [38%] versus n = 3 [10%], P = 0.0067). The most common GI infections were Giardia lamblia (n = 14 [15%]) and Clostridium difficile (n = 4 [4%]). Forty-three (45%) patients with GI symptoms underwent colonoscopy, esophagogastroduodenoscopy or both. The most common findings were inflammation, nodular lymphoid hyperplasia, reduced plasma cells and increased intraepithelial lymphocytes.

CONCLUSIONS

This is the largest study on CVID patients in a North American setting. The majority of patients experienced GI symptoms. Future studies should study response to treatment for GI disease among patients with CVID.

Primary Humoral Immune Deficiencies: Overlooked Mimickers of Chronic Immune-Mediated Gastrointestinal Diseases in Adults

In recent years, the incidence of immune-mediated gastrointestinal disorders, including celiac disease (CeD) and inflammatory bowel disease (IBD), is increasingly growing worldwide. This generates a need to elucidate the conditions that may compromise the diagnosis and treatment of such gastrointestinal disorders. It is well established that primary immunodeficiencies (PIDs) exhibit gastrointestinal manifestations and mimic other diseases, including CeD and IBD. PIDs are often considered pediatric ailments, whereas between 25 and 45% of PIDs are diagnosed in adults. The most common PIDs in adults are the selective immunoglobulin A deficiency (SIgAD) and the common variable immunodeficiency (CVID). A trend to autoimmunity occurs, while gastrointestinal disorders are common in both diseases. Besides, the occurrence of CeD and IBD in SIgAD/CVID patients is significantly higher than in the general population. However, some differences concerning diagnostics and management between enteropathy/colitis in PIDs, as compared to idiopathic forms of CeD/IBD, have been described. There is an ongoing discussion whether CeD and IBD in CVID patients should be considered a true CeD and IBD or just CeD-like and IBD-like diseases. This review addresses the current state of the art of the most common primary immunodeficiencies in adults and co-occurring CeD and IBD.

Rethinking mucosal antibody responses: IgM, IgG and IgD join IgA

Humoral immune responses at mucosal surfaces have historically focused on IgA. Growing evidence highlights the complexity of IgA-inducing pathways and the functional impact of IgA on mucosal commensal bacteria. In the gut, IgA contributes to the establishment of a mutualistic host-microbiota relationship that is required to maintain homeostasis and prevent disease. This Review discusses how mucosal IgA responses occur in an increasingly complex humoral defence network that also encompasses IgM, IgG and IgD. Aside from integrating the protective functions of IgA, these hitherto neglected mucosal antibodies may strengthen the communication between mucosal and systemic immune compartments.

Gastrointestinal findings in 26 adults with common variable immunodeficiency: The fickle nature of the disease manifests in gastrointestinal biopsies

BACKGROUND/AIMS

The aim of the present study was to demonstrate the histopathological findings in gastrointestinal (GI) biopsies in adults with common variable immunodeficiency (CVID).

MATERIALS AND METHODS

A total of 172 GI biopsies of 26 patients with CVID obtained over a 16-year period were reevaluated. Findings were analyzed using descriptive analyzes and χ2 test.

RESULTS

Female-to-male ratio was 1.36. The median age at diagnosis was 36±13.94 (16-72) years. Chronic esophagitis was noted in 3 patients. The absence of plasma cells in the stomach, duodenum, and colon was observed in 16, 14, and 9 patients, respectively. Divergent results for the presence of plasma cells in concurrent stomach and duodenum samples were found in 11 (44%) patients. Nodular lymphoid hyperplasia (NLH) was notable in the duodenum (56%). The mean number of eosinophils in one high-power field was significantly higher in duodenal biopsies with NLH (27.21 vs. 14.37, p=0.002). Active inflammation was more prominent in the colon (91%) than in the stomach (65%) and duodenum (60%). Helicobacter pylori infection was found in 57.6%, including a case with persistent infection by the coccoid form. Celiac-like villous blunting and increased intraepithelial lymphocytes were seen in 40% and 24%, respectively. In addition, 23% had giardiasis associated with acute duodenitis and duodenal NLH (p<0.05).

CONCLUSION

CVID gastroenteropathy is a challenging entity, and due to the heterogeneity in the presence and distribution of plasma cells throughout the GI tract and diverse disease course, multiple concurrent biopsies may be needed for tissue diagnosis. Duodenal CVID may present with villous alterations and giardiasis, and NLH appears to be an important clue in the duodenum. The association between duodenal NLH and eosinophil infiltration deserves further investigation.

The Usefulness of Scintigraphic Studies in the Assessment of Asymptomatic Bowel Disease in Patients with Primary Antibody Diseases

Enteropathy may be the first presentation of immunodeficiency or it may occur during the course of the disease and in association with malabsorption in patients affected by primary antibody diseases. For these patients, immunoglobulin G (IgG) replacement therapy prevents infectious and non-infectious complications. Nonetheless some patients cannot achieve optimal IgG trough levels, even when treated with high Ig doses in absence of protein-losing syndromes. We investigated seven patients affected by common variable immunodeficiencies (CVIDs) and treated with high Ig doses (600–800 mg/kg/month) showing low IgG trough level. Patients underwent abdominal scintigraphy with human polyclonal immunoglobulin G labeled with 99mTc and with white blood cells labeled by 111 Indium-oxinate to investigate asymptomatic bowel inflammation. A concentration of labeled leukocytes in abdominal segments greater than that observed with human polyclonal immunoglobulin G was evident only in one patient. In five patients a slight concentration of both radiopharmaceuticals was reported, due to mild intestinal inflammatory response. These data might be related to mild increase of capillary permeability in the absence of inflammation leukocyte mediated. This study discloses a new cause of IgG-accelerated catabolism due to inflammatory bowel conditions without diarrhea in CVID patients.

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.

Lack of Gut Secretory Immunoglobulin A in Memory B-Cell Dysfunction-Associated Disorders: A Possible Gut-Spleen Axis

Background: B-1a B cells and gut secretory IgA (SIgA) are absent in asplenic mice. Human immunoglobulin M (IgM) memory B cells, which are functionally equivalent to mouse B-1a B cells, are reduced after splenectomy.

Objective: To demonstrate whether IgM memory B cells are necessary for generating IgA-secreting plasma cells in the human gut.

Methods: We studied intestinal SIgA in two disorders sharing the IgM memory B cell defect, namely asplenia, and common variable immune deficiency (CVID).

Results: Splenectomy was associated with reduced circulating IgM memory B cells and disappearance of intestinal IgA-secreting plasma cells. CVID patients with reduced circulating IgM memory B cells had a reduced frequency of gut IgA⁺ plasma cells and a disrupted film of SIgA on epithelial cells. Toll-like receptor 9 (TLR9) and transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI) induced IgM memory B cell differentiation into IgA⁺ plasma cells in vitro. In the human gut, TACI-expressing IgM memory B cells were localized under the epithelial cell layer where the TACI ligand a proliferation inducing ligand (APRIL) was extremely abundant.

Conclusions: Circulating IgM memory B cell depletion was associated with a defect of intestinal IgA-secreting plasma cells in asplenia and CVID. The observation that IgM memory B cells have a distinctive role in mucosal protection suggests the existence of a functional gut-spleen axis.

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.

Autoimmunity in common variable immunodeficiency

OBJECTIVE

Common variable immunodeficiency (CVID) is a primary immunodeficiency that is clinically heterogeneous, characterized by both infectious and noninfectious complications. Although the hallmark of disease presentation is commonly a history of recurrent sinopulmonary infections, autoimmunity and noninfectious inflammatory conditions are increasingly associated with CVID.

DATA SOURCES

A comprehensive literature search using PubMed of basic science and clinical articles was performed.

STUDY SELECTIONS

Articles discussing the association of autoimmunity with primary immunodeficiency, specifically CVID, were selected.

RESULTS

The most common autoimmune conditions are cytopenias, including immune thrombocytopenia purpura and hemolytic anemia, but organ-specific autoimmune/inflammatory complications involving the gastrointestinal, skin, joints, connective tissue, and respiratory tract. In most cases, immunoglobulin replacement therapy does not ameliorate or treat these inflammatory complications, and additional immunomodulatory treatments are needed.

CONCLUSION

Mechanisms producing these conditions are poorly understood but include cytokine and cellular inflammatory pathways, and loss of tolerance to self-antigens through the multiple signaling molecules and pathways common to tolerance and immune deficiency.

Immunodeficiencies that predispose to pathologies by human oncogenic γ-herpesviruses

Human γ-herpesviruses include the closely related tumor viruses Epstein Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV). EBV is the most growth-transforming pathogen known and is linked to at least seven human malignancies. KSHV is also associated with three human cancers. Most EBV- and KSHV-infected individuals fortunately remain disease-free despite persistent infection and this is likely due to the robustness of the immune control that they mount against these tumor viruses. However, upon immune suppression EBV- and KSHV-associated malignancies emerge at increased frequencies. Moreover, primary immunodeficiencies with individual mutations that predispose to EBV or KSHV disease allow us to gain insights into a catalog of molecules that are required for the immune control of these tumor viruses. Curiously, there is little overlap between the mutation targets that predispose individuals to EBV versus KSHV disease, even so both viruses can infect the same host cell, human B cells. These differences will be discussed in this review. A better understanding of the crucial components in the near-perfect life-long immune control of EBV and KSHV should allow us to target malignancies that are associated with these viruses, but also induce similar immune responses against other tumors.

Activation of Peripheral Blood CD4+ T-Cells in IBS is not Associated with Gastrointestinal or Psychological Symptoms

Immune activation may underlie the pathogenesis of irritable bowel syndrome (IBS), but the evidence is conflicting. We examined whether peripheral CD4+ T-cells from IBS patients demonstrated immune activation and changes in cytokine production. To gain mechanistic insight, we examined whether immune activation correlated with psychological stress and changing symptoms over time. IBS patients (n = 29) and healthy volunteers (HV; n = 29) completed symptom and psychological questionnaires. IBS patients had a significant increase in CD4+ T-cells expressing the gut homing marker integrin β7 (p = 0.023) and lymphoid marker CD62L (p = 0.026) compared to HV. Furthermore, phytohaemagglutinin stimulated CD4+ T-cells from IBS-D patients demonstrated increased TNFα secretion when compared to HV (p = 0.044). Increased psychological scores in IBS did not correlate with TNFα production, while stress hormones inhibited cytokine secretion from CD4+ T-cells of HV in vitro. IBS symptoms, but not markers of immune activation, decreased over time. CD4+ T-cells from IBS-D patients exhibit immune activation, but this did not appear to correlate with psychological stress measurements or changing symptoms over time. This could suggest that immune activation is a surrogate of an initial trigger and/or ongoing parallel peripheral mechanisms.

Inflammatory Bowel Disease: What Very Early Onset Disease Teaches Us

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract, of which ulcerative colitis and Crohn's disease are the 2 most prevailing entities. Very early onset IBD (VEO-IBD) children diagnosed with IBD under age 6 years. Although the etiology of IBD is mostly unknown, it involves a complex interaction among host genetics, microbiota, environmental factors, and aberrant immune responses. Advances in the understanding of the genetic contribution, which appears to be much more significant in younger children, gives us a useful insight into the pathogenesis and potential future therapeutic targets in IBD.

[Features and management of very early onset inflammatory bowel disease]

Inflammatory bowel disease (IBD) is a chronic nonspecific intestinal inflammatory disease of unknown etiology. This disease includes three main types: Crohn&prime;s disease (CD), ulcerative colitis (UC), and IBD-unclassified (IBD-U). IBD is frequently presented in adults, but in recent years, there is a rising incidence in pediatric populations. Very early onset IBD (VEO-IBD) is a fraction of pediatric IBD, but they have exclusive phenotypic and genetic characteristics such that they are accompanied by severe disease course and resistance to conventional therapy. The purpose of this review is to provide a contemporary overview of the clinical features, pathogenesis, and management of VEO-IBD.

Common Variable Immunodeficiency Non-Infectious Disease Endotypes Redefined Using Unbiased Network Clustering in Large Electronic Datasets

Common variable immunodeficiency (CVID) is increasingly recognized for its association with autoimmune and inflammatory complications. Despite recent advances in immunophenotypic and genetic discovery, clinical care of CVID remains limited by our inability to accurately model risk for non-infectious disease development. Herein, we demonstrate the utility of unbiased network clustering as a novel method to analyze inter-relationships between non-infectious disease outcomes in CVID using databases at the United States Immunodeficiency Network (USIDNET), the centralized immunodeficiency registry of the United States, and Partners, a tertiary care network in Boston, MA, USA, with a shared electronic medical record amenable to natural language processing. Immunophenotypes were comparable in terms of native antibody deficiencies, low titer response to pneumococcus, and B cell maturation arrest. However, recorded non-infectious disease outcomes were more substantial in the Partners cohort across the spectrum of lymphoproliferation, cytopenias, autoimmunity, atopy, and malignancy. Using unbiased network clustering to analyze 34 non-infectious disease outcomes in the Partners cohort, we further identified unique patterns of lymphoproliferative (two clusters), autoimmune (two clusters), and atopic (one cluster) disease that were defined as CVID non-infectious endotypes according to discrete and non-overlapping immunophenotypes. Markers were both previously described {high serum IgE in the atopic cluster [odds ratio (OR) 6.5] and low class-switched memory B cells in the total lymphoproliferative cluster (OR 9.2)} and novel [low serum C3 in the total lymphoproliferative cluster (OR 5.1)]. Mortality risk in the Partners cohort was significantly associated with individual non-infectious disease outcomes as well as lymphoproliferative cluster 2, specifically (OR 5.9). In contrast, unbiased network clustering failed to associate known comorbidities in the adult USIDNET cohort. Together, these data suggest that unbiased network clustering can be used in CVID to redefine non-infectious disease inter-relationships; however, applicability may be limited to datasets well annotated through mechanisms such as natural language processing. The lymphoproliferative, autoimmune, and atopic Partners CVID endotypes herein described can be used moving forward to streamline genetic and biomarker discovery and to facilitate early screening and intervention in CVID patients at highest risk for autoimmune and inflammatory progression.

Immmunodeficiencies and autoimmune diseases: common variable immunodeficiency and Crohn-like

Common variable immunodeficiency (CVI) gives a major risk of principally respiratory and digestive infections. It is associated with autoimmune diseases, granulomatous process and neoplasias. The digestive clinic is common, in 10% of patients it is the only symptom, and 60 % present chronic diarrhea. Clinically it can be confused and related with other pathologies such as inflammatory bowel disease which is infrequent (2-13%). We present the case of a patient with CVI with digestive symptoms being diagnosed of Crohn-like disease with extent ileal affectation. The main treatment of these patients is the same as classical Crohn disease although in the most severe cases, as this one, the use of immunosupresors is necessary. At this time the patient remains on clinical remmision with infliximab. She presented a previous adverse reaction with adalimumab. The few case series in this pathology makes the treatment with immunomodulators in this immunodeficiency a real diagnostic and therapeutic challenge.

Mechanism-Based Strategies for the Management of Autoimmunity and Immune Dysregulation in Primary Immunodeficiencies

A broad spectrum of autoimmunity is now well described in patients with primary immunodeficiencies (PIDs). Management of autoimmune disease in the background of PID is particularly challenging given the seemingly discordant goals of immune support and immune suppression. Our growing ability to define the molecular underpinnings of immune dysregulation has facilitated novel targeted therapeutics. This review focuses on mechanism-based treatment strategies for the most common autoimmune and inflammatory complications of PID including autoimmune cytopenias, rheumatologic disease, and gastrointestinal disease. We aim to provide guidance regarding the rational use of these agents in the complex PID patient population.

Inflammatory bowel disease caused by primary immunodeficiencies-Clinical presentations, review of literature, and proposal of a rational diagnostic algorithm

Inflammatory bowel diseases (IBD) including Crohn's disease (CD) and ulcerative colitis have a multifactorial pathogenesis with complex interactions between polygenetic predispositions and environmental factors. However, IBD can also be caused by monogenic diseases, such as primary immunodeficiencies (PID). Recently, an increasing number of these altogether rare diseases have been described to present often primarily, or solely, as IBD. Early recognition of these conditions enables adaption of therapies and thus directly benefits the course of IBDs. Here, we discuss the different clinical presentations in IBD and characteristic features of patient's history, clinical findings, and diagnostic results indicative for a causative PID. Possible predictors are early onset of disease, necessity of parenteral nutrition, failure to respond to standard immunosuppressive therapy, parental consanguinity, increased susceptibility for infections, certain histopathologic findings, and blood tests that are atypical for classic IBD. We illustrate this with exemplary case studies of IBD due to NEMO deficiency, chronic granulomatous disease, common variable immunodeficiency, CTLA-4 and LRBA deficiency. Taking these factors into account, we propose a diagnostic pathway to enable early diagnosis of IBD due to PID.

Total and High Molecular Weight Adiponectin Expression Is Decreased in Patients with Common Variable Immunodeficiency: Correlation with Ig Replacement Therapy

Adiponectin (Acrp30) is an adipokine widely studied for its beneficial metabolic properties. It circulates as low molecular weight (LMW), medium molecular weight (MMW), and high molecular weight (HMW) oligomers. The latter exerts the most potent biological effects. Acrp30 attracted renewed interest with the finding that it was associated with the development and progression of immune disorders. The mechanisms underlying this association and the role of Acrp30 in the pathophysiology of immune-mediated conditions remain unknown. Common variable immunodeficiency (CVID) is a primary immunodeficiency characterized by chronic activation of the immune system, impaired antibody production, and imbalanced cytokine production. In the attempt to shed light on the expression of Acrp30 in CVID, we: (a) investigated total Acrp30 and its oligomerization state in CVID patients undergoing maintenance Ig replacement therapy; (b) assessed the effects of Ig replacement therapy on Acrp30 expression in treatment-naïve CVID patients, namely, patients not treated before diagnosis, before and after the first Ig administration; and (c) evaluated the correlation between Acrp30 levels and clinical phenotypes of the disease. As controls, we analyzed healthy subjects and patients affected by a non-immunodeficiency chronic inflammatory demyelinating polyneuropathy (CIDP), before and after Ig infusion. We found that total Acrp30 and HMW oligomers were decreased in CVID but not in CIDP patients versus controls. Moreover, Acrp30 levels were correlated with IgA levels and were associated with two CVID phenotypes, namely, autoimmune cytopenia and enteropathy. Receiver operating characteristic curve analysis indicated that Acrp30 modulation is specific for CVID patients. Acrp30 and HMW levels quickly and dramatically increased after Ig infusion only in eight treatment-naïve CVID patients but not in five CIDP patients. This finding indicates that Ig administration per se is not able to induce an increase of Acrp30, but the specific cellular and/or molecular background proper of CVID seems to be essential. In conclusion, our data indicate that Acrp30 is specifically related to CVID activity. Further studies are required to understand the biological role of Acrp30 and its possible use as disease biomarker in CVID.

National Institutes of Health Hematopoietic Cell Transplantation Late Effects Initiative: The Immune Dysregulation and Pathobiology Working Group Report

Immune reconstitution after hematopoietic stem cell transplantation (HCT) beyond 1 year is not completely understood. Many transplant recipients who are free of graft-versus-host disease (GVHD) and not receiving any immunosuppression more than 1 year after transplantation seem to be able to mount appropriate immune responses to common pathogens and respond adequately to immunizations. However, 2 large registry studies over the last 2 decades seem to indicate that infection is a significant cause of late mortality in some patients, even in the absence of concomitant GVHD. Research on this topic is particularly challenging for several reasons. First, there are not enough long-term follow-up clinics able to measure even basic immune parameters late after HCT. Second, the correlation between laboratory measurements of immune function and infections is not well known. Third, accurate documentation of infectious episodes is notoriously difficult. Finally, it is unclear what measures can be implemented to improve the immune response in a clinically relevant way. A combination of long-term multicenter prospective studies that collect detailed infectious data and store samples as well as a national or multinational registry of clinically significant infections (eg, vaccine-preventable severe infections, opportunistic infections) could begin to address our knowledge gaps. Obtaining samples for laboratory evaluation of the immune system should be both calendar and eventdriven. Attention to detail and standardization of practices regarding prophylaxis, diagnosis, and definitions of infections would be of paramount importance to obtain clean reliable data. Laboratory studies should specifically address the neogenesis, maturation, and exhaustion of the adaptive immune system and, in particular, how these are influenced by persistent alloreactivity, inflammation, and viral infection. Ideally, some of these long-term prospective studies would collect information on long-term changes in the gut microbiome and their influence on immunity. Regarding enhancement of immune function, prospective measurement of the response to vaccines late after HCT in a variety of clinical settings should be undertaken to better understand the benefits as well as the limitations of immunizations. The role of intravenous immunoglobulin is still not well defined, and studies to address it should be encouraged.

Approach to the Management of Autoimmunity in Primary Immunodeficiency

Primary immunodeficiency diseases (PIDs) consist of a genetically heterogeneous group of immune disorders that affect distinct elements of the immune system. PID patients are more prone to infections and non-infectious complications, particularly autoimmunity. The concomitance of immunodeficiency and autoimmunity appears to be paradoxical and leads to difficulty in the management of autoimmune complications in PID patients. Therefore, management of autoimmunity in patients with PID requires special considerations because dysregulations and dysfunctions of the immune system along with persistent inflammation impair the process of diagnosis and treatment.

Ulcerative colitis in a patient with common variable immunodeficiency: does the treatment differ from the routine?

Common variable immunodeficiency (CVID) is associated with gastrointestinal manifestations, in particular diarrhea (1,2). It is linked to autoimmune disorders such as nodular lymphoid hyperplasia (NLH), possibly increasing the risk of lymphoma (3). The prevalence of chronic inflammatory bowel disease (CIBD) in these patients is increased, above all Crohn's disease (4,5) and its treatment does not seem to differ from the standard (2). We were presented with a patient with CVID and ulcerative colitis treated in the conventional manner.

Gastrointestinal Disorders Associated with Common Variable Immune Deficiency (CVID) and Chronic Granulomatous Disease (CGD)

Common variable immune deficiency (CVID) and chronic granulomatous disease (CGD) are two of the well-characterized primary immune deficiencies with distinct pathologic defects. While CVID is predominantly a disorder of the adaptive immune system, in CGD, innate immunity is impaired. In both syndromes, the clinical manifestations include an increased susceptibility to infections and a number of non-infectious, inflammatory conditions including systemic autoimmunity, as well as organ-specific pathology. Among the organ-associated disorders, gastrointestinal (GI) manifestations are one of the most intractable. As such, non-infectious inflammatory disorders of the GI tract are clinically challenging as they have protean manifestations, often resembling inflammatory bowel disease (IBD) or celiac disease, are notoriously difficult to treat, and hence are associated with significant morbidity and mortality. Therefore, assessing the pathogenesis and defining appropriate therapeutic approaches for GI disease in patients with CVID and CGD is imperative.

Application of diagnostic and treatment criteria for common variable immunodeficiency disorder

Common variable immunodeficiency disorder (CVID) is the most frequent symptomatic primary immune deficiency disorder in adults. It probably comprises a spectrum of polygenic disorders, with hypogammaglobulinemia being the overarching feature. While the majority of patients with CVID can be identified with relative ease, a significant proportion can present with minimal symptoms in spite of profound laboratory abnormalities. Here we discuss three patients who were presented to the Auckland Hospital immunoglobulin treatment committee to determine if they qualified for immunoglobulin replacement. Two were asymptomatic with profound laboratory abnormalities while the third patient was severely ill with extensive bronchiectasis. The third patient had less severe laboratory abnormalities compared with the two asymptomatic patients. We have applied four sets of published diagnostic and treatment criteria to these patients to compare their clinical utility. We have chosen these patients from the broad phenotypic spectrum of CVID, as this often illustrates differences in diagnostic and treatment criteria.

Genetics of inflammatory bowel disease from multifactorial to monogenic forms

Inflammatory bowel disease (IBD) is a group of chronic multifactorial disorders. According to a recent study, the number of IBD association loci is increased to 201, of which 37 and 27 loci contribute specifically to the development of Crohn’s disease and ulcerative colitis respectively. Some IBD associated genes are involved in innate immunity, in the autophagy and in the inflammatory response such as NOD2, ATG16L1 and IL23R, while other are implicated in immune mediated disease (STAT3) and in susceptibility to mycobacterium infection (IL12B). In case of early onset of IBD (VEO-IBD) within the 6^th year of age, the disease may be caused by mutations in genes responsible for severe monogenic disorders such as the primary immunodeficiency diseases. In this review we discuss how these monogenic disorders through different immune mechanisms can similarly be responsible of VEO-IBD phenotype. Moreover we would highlight how the identification of pathogenic genes by Next Generation Sequencing technologies can allow to obtain a rapid diagnosis and to apply specific therapies.

DNA Repair Cofactors ATMIN and NBS1 Are Required to Suppress T Cell Activation

Proper development of the immune system is an intricate process dependent on many factors, including an intact DNA damage response. The DNA double-strand break signaling kinase ATM and its cofactor NBS1 are required during T cell development and for the maintenance of genomic stability. The role of a second ATM cofactor, ATMIN (also known as ASCIZ) in T cells is much less clear, and whether ATMIN and NBS1 function in synergy in T cells is unknown. Here, we investigate the roles of ATMIN and NBS1, either alone or in combination, using murine models. We show loss of NBS1 led to a developmental block at the double-positive stage of T cell development, as well as reduced TCRα recombination, that was unexpectedly neither exacerbated nor alleviated by concomitant loss of ATMIN. In contrast, loss of both ATMIN and NBS1 enhanced DNA damage that drove spontaneous peripheral T cell hyperactivation, proliferation as well as excessive production of proinflammatory cytokines and chemokines, leading to a highly inflammatory environment. Intriguingly, the disease causing T cells were largely proficient for both ATMIN and NBS1. In vivo this resulted in severe intestinal inflammation, colitis and premature death. Our findings reveal a novel model for an intestinal bowel disease phenotype that occurs upon combined loss of the DNA repair cofactors ATMIN and NBS1.