Pathogenesis and treatment of gastrointestinal disease in antibody deficiency syndromes

A Nationwide Study of Severe and Protracted Diarrhoea in Patients with Primary Immunodeficiency Diseases

Diarrhoea lasting longer than 14 days and failing to respond to conventional management is defined as severe and protracted diarrhoea (SD). In this study, we investigated the prevalence, pathogens and prognosis of SD in primary immunodeficiency diseases (PIDs). Among 246 patients with predominantly paediatric-onset PIDs from 2003–2015, 21 [Btk (six), IL2RG (four), WASP, CD40L, gp91 (three each), gp47, RAG2 (one each)] and five [CVID (four), SCID (one)] without identified mutations had SD before prophylactic treatment. Detectable pathogens included pseudomonas, salmonella (six each), E. coli, cytomegalovirus, coxsackie virus and cryptosporidium (one each), all of whom improved after a mean 17 days of antibiotics and/or IVIG treatment. Seven (7/26; 27.0%) patients died [respiratory failure (four), lymphoma, sepsis and intracranial haemorrhage (one each)]. The patients with WAS, CGD and CD40L and SD had a higher mortality rate than those without. Another five males with mutant XIAP, STAT1, FOXP3 (one each) and STAT3 (two) had undetectable-pathogenic refractory diarrhoea (RD) that persisted >21 days despite aggressive antibiotic/steroid treatment and directly resulted in mortality. For the patients with RD without anti-inflammatory optimization, those with mutant XIAP and FOXP3 died of Crohn’s-like colitis and electrolyte exhaustion in awaiting transplantation, while transplantation cured the STAT1 patient.

Gastrointestinal disorders next to respiratory infections as leading symptoms of X-linked agammaglobulinemia in children - 34-year experience of a single center

INTRODUCTION

Respiratory tract infections constitute the most frequent manifestation of X-linked agammaglobulinemia (XLA). There are not many papers elucidating gastrointestinal (GI) disorders, including inflammatory bowel disease (IBD), in such patients. The aim of the study was to evaluate the occurrence of gastrointestinal disorders and IBD compared to respiratory tract infections in XLA individuals.

MATERIAL AND METHODS

Of 1563 patients with primary immunodeficiencies diagnosed in the Department of Immunology, the Children's Memorial Health Institute (CMHI), 66 boys had a provisional diagnosis of agammaglobulinemia. Forty-four subjects fulfilled definitive ESID (European Society for Immunodeficiencies) diagnostic criteria of XLA. A retrospective analysis of medical history of XLA patients was undertaken.

RESULTS

Recurrent respiratory tract infections, particularly bronchitis (73%) and pneumonia (59%), were the most common symptoms of XLA. The GI disorders constituted the next main manifestation (63.6%), followed by upper respiratory tract infections. Twenty-six of 28 XLA patients with GI disorders complained of diarrhea, which was resolved generally after immunoglobulin therapy introduction. Single but prolonged episodes of Campylobacter jejuni diarrhea were reported in two individuals. Inflammatory bowel disease of mild to moderate activity was diagnosed in 1 patient, and local enteritis of mild activity in another one.

CONCLUSIONS

Gastrointestinal disorders were one of the main manifestations of XLA, reported almost as often as lower respiratory tract infections. The most common GI symptom was diarrhea, which usually resolved after immunoglobulin therapy was started. Infections caused by Giardia lamblia were reported occasionally. Inflammatory bowel disease was diagnosed quite exceptionally, which presumably may be connected with normal T cell immunity.

Identification of Variants in Genes Associated with Single-gene Inflammatory Bowel Disease by Whole-exome Sequencing

BACKGROUND

Most cases of inflammatory bowel disease (IBD) are caused by complex host-environment interaction. There are a number of conditions associated with a single-gene mutation, most cases are very early onset (aged < 6 yr), present with a unique form of disease and often have atypical features.

METHODS

Whole-exome data for 147 pediatric patients with IBD were interrogated for a panel of 51 genes associated with monogenic IBD. Observed variation was categorized according to the American College of Medical Genetics (ACMG) guidelines to identify rare, novel, and known variants that might contribute to IBD.

RESULTS

Five hundred seventy-four variants were identified across 51 genes. These were categorized in line with ACMG guidance to remove benign variants and to identify "pathogenic" and "likely pathogenic" variants. In 6 patients, we observed 6 pathogenic variants of which CYBA(c.287+2T>C), COL7A1(c.6501+1G>C), LIG4(p.R814X), and XIAP(p.T470S) were known causative mutations, and FERMT1(p.R271Q) and SKIV2L(c.354+5G>A) were novel. In the 3 patients with XIAP, SKIV2L, and FERMT1 variants, individuals' disease features resembled the monogenic phenotype. This was despite apparent heterozygous carriage of pathogenic variation for the latter 2 genes. The XIAP variant was observed in a hemizygous male.

CONCLUSIONS

Whole-exome sequencing allows for identification of known and de novo potentially causative mutations in genes associated with monogenic IBD. Although these are rare conditions, it is vital to identify causative mutations early to improve prognosis. We postulate that in a subset of IBD, heterozygous mutations (in genes believed to manifest IBD through autosomal recessive inheritance) may contribute to clinical presentation.

Congenital intestinal diarrhoeal diseases: A diagnostic and therapeutic challenge

Congenital diarrhoeal disorders are a heterogeneous group of inherited malabsorptive or secretory diseases typically appearing in the first weeks of life, which may be triggered by the introduction of distinct nutrients. However, they may also be unrecognised for a while and triggered by exogenous factors later on. In principle, they can be clinically classified as osmotic, secretory or inflammatory diarrhoea. In recent years the disease-causing molecular defects of these congenital disorders have been identified. According to the underlying pathophysiology they can be classified into four main groups: 1) Defects of digestion, absorption and transport of nutrients or electrolytes 2) Defects of absorptive enterocyte differentiation or polarisation 3) Defects of the enteroendocrine cells 4) Defects of the immune system affecting the intestine. Here, we describe the clinical presentation of congenital intestinal diarrhoeal diseases, the diagnostic work-up and specific treatment aspects.

Expansion of inflammatory innate lymphoid cells in patients with common variable immune deficiency

BACKGROUND

Common variable immunodeficiency (CVID) is an antibody deficiency treated with immunoglobulin; however, patients can have noninfectious inflammatory conditions that lead to heightened morbidity and mortality.

OBJECTIVES

Modular analyses of RNA transcripts in whole blood previously identified an upregulation of many interferon-responsive genes. In this study we sought the cell populations leading to this signature.

METHODS

Lymphoid cells were measured in peripheral blood of 55 patients with CVID (31 with and 24 without inflammatory/autoimmune complications) by using mass cytometry and flow cytometry. Surface markers, cytokines, and transcriptional characteristics of sorted innate lymphoid cells (ILCs) were defined by using quantitative PCR. Gastrointestinal and lung biopsy specimens of subjects with inflammatory disease were stained to seek ILCs in tissues.

RESULTS

The linage-negative, CD127(+), CD161(+) lymphoid population containing T-box transcription factor, retinoic acid-related orphan receptor (ROR) γt, IFN-γ, IL-17A, and IL-22, all hallmarks of type 3 innate lymphoid cells, were expanded in the blood of patients with CVID with inflammatory conditions (mean, 3.7% of PBMCs). ILCs contained detectable amounts of the transcription factors inhibitor of DNA binding 2, T-box transcription factor, and RORγt and increased mRNA transcripts for IL-23 receptor (IL-23R) and IL-26, demonstrating inflammatory potential. In gastrointestinal and lung biopsy tissues of patients with CVID, numerous IFN-γ(+)RORγt(+)CD3(-) cells were identified, suggesting a role in these mucosal inflammatory states.

CONCLUSIONS

An expansion of this highly inflammatory ILC population is a characteristic of patients with CVID with inflammatory disease; ILCs and the interferon signature are markers for the uncontrolled inflammatory state in these patients.

Peri-operative considerations in the patient with primary immune deficiency: a review

BACKGROUND

Patients with inherited immune deficiency diseases often require surgical procedures, and their immune defects may predispose them to surgical complications.

METHODS

A thorough review of pertinent literature and current practice guidelines on surgery in patients with immune deficiency.

RESULTS

Peri-operative infections are a key, but not a singular, consideration in managing patients with a primary immune deficiency. Bleeding diathesis, gastrointestinal complications, pulmonary complications, and poor incision healing may also be idiosyncratic features unique to particular immune deficiency diseases. Patients with complex genetic syndromes that include immune deficiency also may display non-immunologic abnormalities that are equally important to surgical care.

CONCLUSION

Greater awareness of primary immune deficiencies and a comprehensive evaluation of such patients in close consultation with an immunologist can minimize surgical complications and optimize patient outcomes.

Diagnosing primary immunodeficiency: a practical approach for the non-immunologist

OBJECTIVE

This review will provide an overview of the most common clinical presentations of primary immunodeficiency (PI), navigating through various affected organ systems. The goal is to accurately portray the high variability of this disease and provide a resource that helps to raise the index of suspicion of PI among physicians, aid in recognition of various PI disorders, and trigger more frequent screenings with appropriate referrals to immunologists for further evaluation and treatment.

SUMMARY

Patients with PI comprise more than 200 defined genetic abnormalities. Patients have an array of clinical manifestations, ranging from the most widely associated recurrent and chronic bacterial infections to other associated comorbid conditions involving many organ systems. There is still considerable delay between the onset of symptoms and the time of diagnosis of PI. This review will present an overview of the clinical manifestations that will enhance a physician's recognition of a possible PI. Particular emphasis is placed on the pathogens associated with the specific arm of the immune system that is related to each particular type of PI. The initial immune evaluation is described, which together with the history and physical exam can help focus the physician on the immune compartment most likely associated with a PI.

CONCLUSIONS

Understanding the types of PI and the related clinical manifestations can help physicians see beyond the presenting symptoms and lead to improved recognition and diagnosis of PI. Timely diagnosis is of utmost importance in PI, as recent advances in bone transplantation and immunoglobulin replacement therapy, as well as future gene therapies, provide effective ways to prevent significant mortality and morbidity.

Microbes and B cell development

Animals and many of their chronic microbial inhabitants form relationships of symbiotic mutualism, which occurs when coexisting life-forms derive mutual benefit from stable associations. While microorganisms receive a secure habitat and constant food source from vertebrate hosts, they are required for optimal immune system development and occupy niches otherwise abused by pathogens. Microbes have also been shown to provide vertebrate hosts with metabolic capabilities that enhance energy and nutrient uptake from the diet. The immune system plays a central role in the establishment and maintenance of host-microbe homeostasis, and B lineage cells play a key role in this regulation. Here, I reviewed the structure and function of the microbiota and the known mechanisms of how nonpathogenic microbes influence B cell biology and immunoglobulin repertoire development early in life. I also discuss what is known about how B lineage cells contribute to the process of shaping the composition of commensal/mutualistic microbe membership.

The diagnostic approach to monogenic very early onset inflammatory bowel disease

Patients with a diverse spectrum of rare genetic disorders can present with inflammatory bowel disease (monogenic IBD). Patients with these disorders often develop symptoms during infancy or early childhood, along with endoscopic or histological features of Crohn's disease, ulcerative colitis, or IBD unclassified. Defects in interleukin-10 signaling have a Mendelian inheritance pattern with complete penetrance of intestinal inflammation. Several genetic defects that disturb intestinal epithelial barrier function or affect innate and adaptive immune function have incomplete penetrance of the IBD-like phenotype. Several of these monogenic conditions do not respond to conventional therapy and are associated with high morbidity and mortality. Due to the broad spectrum of these extremely rare diseases, a correct diagnosis is frequently a challenge and often delayed. In many cases, these diseases cannot be categorized based on standard histological and immunologic features of IBD. Genetic analysis is required to identify the cause of the disorder and offer the patient appropriate treatment options, which include medical therapy, surgery, or allogeneic hematopoietic stem cell transplantation. In addition, diagnosis based on genetic analysis can lead to genetic counseling for family members of patients. We describe key intestinal, extraintestinal, and laboratory features of 50 genetic variants associated with IBD-like intestinal inflammation. In addition, we provide approaches for identifying patients likely to have these disorders. We also discuss classic approaches to identify these variants in patients, starting with phenotypic and functional assessments that lead to analysis of candidate genes. As a complementary approach, we discuss parallel genetic screening using next-generation sequencing followed by functional confirmation of genetic defects.

Increased prevalence of gastrointestinal viruses and diminished secretory immunoglobulin a levels in antibody deficiencies

PURPOSE

Gastrointestinal disease occurs frequently in antibody deficiencies. This study aims to explore the relation between gastrointestinal infections and mucosal homeostasis in patients with antibody deficiencies.

METHODS

We performed an observational study including 54 pediatric antibody deficient patients (48 % CVID, 41 % CVID-like, 11 % XLA) and 66 healthy controls. Clinical symptom scores and stool samples were collected prospectively. Stool samples were evaluated for bacteria, parasites, viruses, secretory IgA- and for calprotectin levels. Results were compared between patients and controls.

RESULTS

24 % of antibody deficient patients versus 9 % of healthy controls tested positive for gastrointestinal viruses (p = 0.028). Fecal calprotectin levels were significantly higher in virus positive patients compared to virus negative patients (p = 0.002). However, in controls, fecal calprotectin levels were similar between virus positive and virus negative controls. Moreover, gastrointestinal virus positive patients had low serum IgA levels in 13/14 cases (94 %) versus 40/62 (62 %) patients in the virus negative patient group (p = 0.04). The virus positive patient group also displayed significantly lower secretory IgA levels in stool (median 13 ug/ml) than patients without gastrointestinal viruses detected or healthy controls (median 155 ug/ml) (p = 0.046).

CONCLUSION

We here report an increased prevalence of gastrointestinal viruses and gastrointestinal complaints in antibody deficient patients. Patients that tested positive for gastrointestinal viruses showed diminished serum- and secretory IgA levels, and only in patients, virus positivity was associated with signs of mucosal inflammation. These findings suggest that particularly patients with low IgA are at risk for longstanding replication of gastrointestinal viruses, which may eventually result in CVID-related enteropathy.

[Common variable immunodeficiency: a clinical challenge]

Common variable immunodeficiency (CVID) represents the most common clinically relevant form of primary immunodeficiency. This heterogeneous antibody deficiency syndrome is characterized not only by susceptibility to bacterial respiratory tract infections but displays additional signs of immune dysregulation, such as autoimmunity, chronic inflammation and lymphoproliferation in more than 30 % of the patients. Due to poor awareness the diagnosis is often delayed by 4-6 years. A close collaboration in patient care with a center specialized in primary immunodeficiency is recommended. Regular follow-up visits include assessment of adequate immunoglobulin replacement therapy and screening for manifestation of secondary complications. Regular substitution with intravenous or subcutaneous immunoglobulins has more or less normalized life expectancy of patients with isolated susceptibility to bacterial infections. Therefore, the current core task in the management of CVID patients is the elaboration of more effective and safer forms of prophylaxis and treatment of sequelae of immune dysregulation in the lungs, intestines and liver of affected patients.

Managing comorbid complications in patients with common variable immunodeficiency

OBJECTIVE

To review the literature related to the identification and treatment of secondary complications associated with common variable immunodeficiency (CVID).

DATA SOURCES

The databases of PubMed and Ovid MEDLINE were searched for articles pertaining to comorbid conditions occurring in patients with CVID and effective treatment for or management of those conditions.

STUDY SELECTIONS

Articles were selected based on their relevance to the focus of this review, with an emphasis on clinical phenotypes and biomarkers that can help identify patients with CVID and a secondary complication and issues related to their clinical management.

RESULTS

Noninfective complications have generated a better understanding of the pathogenesis and treatment of CVID by helping to define clinical and immunologic phenotypes of this disease. These clinical phenotypes have been correlated with different survival risks.

CONCLUSION

Emerging and ongoing research on clinical phenotypes and biomarkers of CVID may help identify and better target treatment for patients with CVID who will develop secondary complications. It is hoped that through this improved knowledge of outcomes, more appropriate treatment for patients can be targeted.

Occurrence of autoantibodies for gastrointestinal autoimmune diseases in children with common variable immune deficiency and selected IgA deficiency

INTRODUCTION

Selected IgA deficiency (IgAD) and common variable immune deficiency (CVID) are humoral immunity deficiencies frequent in children. In both these types of immunodeficiency, autoimmune diseases are present in 20-30% of patients, but the disease profiles are different between adults and children. Autoimmune diseases of the gastrointestinal tract (IBD) and celiac disease are typical for children with IgAD and CVID. Diagnosis is based on clinical symptoms, histology of jejunum and antibodies often preceding the onset of disease. However, the diagnosis of IBD and celiac disease is difficult in immune deficiency patients due to weaker or absent production of antibodies, and different jejunum histology, particular in CVID patients.

AIM

Detection of antibodies for autoimmune diseases in children with diagnosis of CVID and IgAD.

MATERIAL AND METHODS

The study included 43 children with CVID and 63 children with IgAD diagnosis. Antibodies typical for celiac disease (for endomysium, tissue transglutaminase and gliadin) were tested in IgA class (CVID patients), IgG class (IgAD, CVID patients) and found in 16 patients (3 - CVID, 13 - IgAD).

RESULTS

Antibodies for IBD (for Saccharomyces cerevisiae antigen - ASCA, goblet cells - Gab, neutrophil's cytoplasm - ANCA, pancreatic cells - Pab) were noted in 17 patients (7 - CVID, 10 - IgAD). Celiac disease was diagnosed in two children with mild and unspecific clinical symptoms followed by introduction of a gluten-free diet. The remaining children with present antibodies but without clinical symptoms involving the gastrointestinal tract are under careful clinical observation with antibody assay every 6 months.

CONCLUSIONS

The antibodies are produced despite impaired humoral immunity but the level might be low so the lower limit of positive results is postulated.

Gastric signet ring carcinoma in a patient with ataxia-telangiectasia: a case report and review of the literature

Ataxia-telangiectasia (A-T) is an autosomal recessive primary immunodeficiency disease characterized by progressive cerebellar ataxia, telangiectasia, sinopulmoner recurrent infections, and cancer susceptibility. Individuals with A-T are known to be at increased risk of certain malignancies including leukemia, lymphoma, and breast and gastric cancer. We present an 18-year-old case of A-T with Hashimoto thyroiditis who admitted with complaints of nausea, vomiting, anorexia, and weight loss. An upper endoscopic biopsy revealed gastric signet ring cell carcinoma. To the best of our knowledge, we report the first case of signet ring cell carcinoma in the patient with A-T. Our experience with occurrence of Hashimoto thyroiditis and gastric signet ring cell carcinoma in the same case of A-T underlines that the clinicians handling A-T must be vigilant about both malignancy and autoimmune disorders.

The variable in common variable immunodeficiency: a disease of complex phenotypes

Common variable immunodeficiency (CVID) is the most common and clinically most important severe primary antibody deficiency and is characterized by low levels of IgG, IgA, and/or IgM, with a failure to produce specific antibodies. This diagnostic category represents a heterogeneous group of disorders, which present not only with acute and chronic infections but also with a range of inflammatory and autoimmune disorders as well as an increased incidence of lymphoma and other malignancies. Patients can now be categorized into distinct clinical phenotypes based on analysis of large cohort studies and be further stratified by immunologic laboratory testing. The biologic importance of this categorization is made clear by the 11-fold increase in mortality if even one of these phenotypes (cytopenias, lymphoproliferation, or enteropathy) is present. Limited progress in defining the underlying molecular causes has been made with known causative single gene defects accounting for only 3% of cases, and, for this and the reasons mentioned above, CVID remains resolute in its variability. This review provides a practical approach to risk stratification of these complex phenotypes by using current clinical categories and laboratory biomarkers. The effects of infection as well as inflammatory and autoimmune complications on different organ systems are discussed alongside strategies to reduce diagnostic delay. Recent developments in diagnostics and therapy are also explored.

Bridging immunity and lipid metabolism by gut microbiota

The human gut is a unique organ in which hundreds of different microbial species find their habitat and in which different host physiologic functions, such as digestion, nutrition, and immunity, coexist. Although all these players were studied separately for decades, recently, there has been an explosion of studies demonstrating the essential role for interactions between these components in gut function. Furthermore, new systems biology methods provide essential tools to study this complex system as a whole and to identify key elements that define the crosstalk between the gut microbiota, immunity, and metabolism. This review is devoted to several human diseases resulting from the disruption in this crosstalk, including immunodeficiency-associated and environmental enteropathies, celiac disease, inflammatory bowel disease, and obesity. We describe findings in experimental models of these diseases and in germ-free animals that help us understand the mechanisms and test new therapeutic strategies. We also discuss current challenges that the field is facing and propose that a new generation of antibiotics, prebiotics, and probiotics coupled with novel, systems biology-driven diagnostics will provide the basis for future personalized therapy.

Interferon signature in the blood in inflammatory common variable immune deficiency

About half of all subjects with common variable immune deficiency (CVID) are afflicted with inflammatory complications including hematologic autoimmunity, granulomatous infiltrations, interstitial lung disease, lymphoid hyperplasia and/or gastrointestinal inflammatory disease. The pathogenesis of these conditions is poorly understood but singly and in aggregate, these lead to significantly increased (11 fold) morbidity and mortality, not experienced by CVID subjects without these complications. To explore the dysregulated networks in these subjects, we applied whole blood transcriptional profiling to 91 CVID subjects, 47 with inflammatory conditions and 44 without, in comparison to subjects with XLA and healthy controls. As compared to other CVID subjects, males with XLA or healthy controls, the signature of CVID subjects with inflammatory complications was distinguished by a marked up-regulation of IFN responsive genes. Chronic up-regulation of IFN pathways is known to occur in autoimmune disease due to activation of TLRs and other still unclarified cytoplasmic sensors. As subjects with inflammatory complications were also more likely to be lymphopenic, have reduced B cell numbers, and a greater reduction of B, T and plasma cell networks, we suggest that more impaired adaptive immunity in these subjects may lead to chronic activation of innate IFN pathways in response to environmental antigens. The unbiased use of whole blood transcriptome analysis may provides a tool for distinguishing CVID subjects who are at risk for increased morbidity and earlier mortality. As more effective therapeutic options are developed, whole blood transcriptome analyses could also provide an efficient means of monitoring the effects of treatment of the inflammatory phenotype.

The immune modifying effects of amino acids on gut-associated lymphoid tissue

The intestine and the gut-associated lymphoid tissue (GALT) are essential components of whole body immune defense, protecting the body from foreign antigens and pathogens, while allowing tolerance to commensal bacteria and dietary antigens. The requirement for protein to support the immune system is well established. Less is known regarding the immune modifying properties of individual amino acids, particularly on the GALT. Both oral and parenteral feeding studies have established convincing evidence that not only the total protein intake, but the availability of specific dietary amino acids (in particular glutamine, glutamate, and arginine, and perhaps methionine, cysteine and threonine) are essential to optimizing the immune functions of the intestine and the proximal resident immune cells. These amino acids each have unique properties that include, maintaining the integrity, growth and function of the intestine, as well as normalizing inflammatory cytokine secretion and improving T-lymphocyte numbers, specific T cell functions, and the secretion of IgA by lamina propria cells. Our understanding of this area has come from studies that have supplemented single amino acids to a mixed protein diet and measuring the effect on specific immune parameters. Future studies should be designed using amino acid mixtures that target a number of specific functions of GALT in order to optimize immune function in domestic animals and humans during critical periods of development and various disease states.

Multi-faceted functions of secretory IgA at mucosal surfaces

Secretory IgA (SIgA) plays an important role in the protection and homeostatic regulation of intestinal, respiratory, and urogenital mucosal epithelia separating the outside environment from the inside of the body. This primary function of SIgA is referred to as immune exclusion, a process that limits the access of numerous microorganisms and mucosal antigens to these thin and vulnerable mucosal barriers. SIgA has been shown to be involved in avoiding opportunistic pathogens to enter and disseminate in the systemic compartment, as well as tightly controlling the necessary symbiotic relationship existing between commensals and the host. Clearance by peristalsis appears thus as one of the numerous mechanisms whereby SIgA fulfills its function at mucosal surfaces. Sampling of antigen-SIgA complexes by microfold (M) cells, intimate contact occurring with Peyer’s patch dendritic cells (DC), down-regulation of inflammatory processes, modulation of epithelial, and DC responsiveness are some of the recently identified processes to which the contribution of SIgA has been underscored. This review aims at presenting, with emphasis at the biochemical level, how the molecular complexity of SIgA can serve these multiple and non-redundant modes of action.

The many faces of common variable immunodeficiency

Common variable immunodeficiency (CVID) is a rare immune deficiency characterized by low levels of serum IgG, IgA, and/or IgM, with a loss of Ab production. The diagnosis is most commonly made in adults between the ages of 20 and 40 years, but both children and much older adults can be found to have this immune defect. The range of clinical manifestations is broad, including acute and chronic infections, inflammatory and autoimmune diseases, and an increased incidence of cancer and lymphoma. For all of these reasons, the disease phenotype is both heterogeneous and complex. In the past few years, data from large patient registries have revealed that both selected laboratory markers and clinical phenotyping may aid in separating groups of subjects into biologically relevant categories. CVID consists of 2 phenotypes, 1 in which infections are the characteristic and another in which impressive inflammatory and/or hematologic complications also develop, including lymphadenopathy, splenomegaly, autoimmune cytopenias, enteropathy, and/or and granulomatous disease. These phenotypes appear to be stable, are related to immunologic and inflammatory markers, and are predictive of outcomes. This review outlines current understanding about this syndrome based on studies of large cohorts, highlighting the evaluation and treatment of complications and, in particular, the autoimmune and inflammatory conditions that affect these patients.

Selective IgA deficiency mimicking Churg-Strauss syndrome and hypereosinophilic syndrome: a case report

Selective IgA deficiency (SIgAD) is the most common type of primary immunoglobulin deficiency. Most individuals with SIgAD are asymptomatic. However, some patients are associated with allergic and autoimmune disease. SIgAD is included in the list of differential diagnoses of eosinophilia. We experienced a patient who initially presented with abdominal pain and eosinophilia. A >1-year follow-up revealed SIgAD, and we had difficulty differentiating it from Churg-Strauss syndrome (CSS) or hypereosinophilic syndrome (HES). A 66-year-old Japanese male presented with a history of recurrent abdominal pain. A diagnostic work-up revealed eosinophilia, eosinophilic gastritis, eosinophilic pneumonia, and SIgAD over 1 year of clinical observation. He also suffered from asthma and sinusitis. Anti-neutrophil cytoplasmic antibody was negative and vasculitis was not detected in the obtained tissue specimens of stomach, lung, nose and skin. The patient showed no evidence of drug ingestion, parasitic infections, or malignant neoplasms. Although we cannot rule out prevasculitic CSS and idiopathic HES, the whole clinical picture in this patient can be explained most consistently by SIgAD.

The many faces of common variable immunodeficiency

Common variable immunodeficiency (CVID) is a rare immune deficiency characterized by low levels of serum IgG, IgA, and/or IgM, with a loss of Ab production. The diagnosis is most commonly made in adults between the ages of 20 and 40 years, but both children and much older adults can be found to have this immune defect. The range of clinical manifestations is broad, including acute and chronic infections, inflammatory and autoimmune diseases, and an increased incidence of cancer and lymphoma. For all of these reasons, the disease phenotype is both heterogeneous and complex. In the past few years, data from large patient registries have revealed that both selected laboratory markers and clinical phenotyping may aid in separating groups of subjects into biologically relevant categories. CVID consists of 2 phenotypes, 1 in which infections are the characteristic and another in which impressive inflammatory and/or hematologic complications also develop, including lymphadenopathy, splenomegaly, autoimmune cytopenias, enteropathy, and/or and granulomatous disease. These phenotypes appear to be stable, are related to immunologic and inflammatory markers, and are predictive of outcomes. This review outlines current understanding about this syndrome based on studies of large cohorts, highlighting the evaluation and treatment of complications and, in particular, the autoimmune and inflammatory conditions that affect these patients.

Hematological manifestations of celiac disease

Celiac disease, an autoimmune disease once thought to be uncommon, is now being increasingly identified. Our improved diagnostic modalities have allowed us to diagnose more and more patients with atypical symptoms who improve on gluten-free diet (GFD). We discuss here the latest findings regarding the various hematological manifestations of celiac disease and their management. Anemia remains the most common hematological manifestation of celiac disease due to many mechanisms, and can be the sole presenting symptom. Other manifestations include thrombocytosis and thrombocythemia, leukopenia, thromboembolism, increased bleeding tendency, IgA deficiency, splenic dysfunction, and lymphoma. The diagnosis of celiac disease should always be kept in mind when a patient presents with unexplained and isolated hematological finding. Once diagnosed, patients should adhere to GFD and be educated about the potential complications of this disease. We herein present an algorithm for adequate management and follow-up.

The significance of duodenal mucosal atrophy in patients with common variable immunodeficiency: a clinical and histopathologic study

Gastrointestinal manifestations and villous atrophy can be seen in patients with common variable immunodeficiency (CVID). In some patients, infectious agents may be responsible, whereas in others, celiac disease (CD) may be the cause. In this study, we investigate the causes and the histopathologic features seen in patients with CVID. Eleven patients with CVID and villous atrophy underwent duodenal biopsies, human leukocyte antigen (HLA) typing, and testing for all celiac antibodies. Fifteen patients with CVID and normal villi and 6 patients with CD but without CVID served as controls. Histologic response to a gluten-free diet (GFD) allowed a diagnosis of CD in 3 of 11 patients. In the remaining 8, the lack of a histologic response to a GFD or HLA typing excluded CD. Celiac antibodies gave conflicting results and were of no help. Polymorphonuclear infiltrates and lesions like graft-versus-host disease are seen more often in flat mucosa unresponsive to a GFD. However, the specificity of these findings remains to be determined and response to a GFD remains the only diagnostic criteria for CD in these patients. Villous atrophy was gluten-sensitive in 3 of 11 patients with CVID. It was not related to gluten-responsive CD in most patients.

The role of prolonged viral gastrointestinal infections in the development of immunodeficiency-related enteropathy

Patients with primary immunodeficiencies are prone to develop enteropathy of unknown pathogenesis. We hypothesize that ineffective clearance of gastrointestinal pathogens, particularly viruses, in combination with defective immune regulation may cause inflammatory enteropathy in certain immunodeficient hosts. We reviewed publications related to prolonged enteric viral infection, immunodeficiency, and the subsequent development of inflammatory enteropathy. Prolonged infection with especially enteroviral infections was reported more often in immunocompromised hosts than in healthy individuals. Protracted enteric viral shedding was not always associated with the presence or duration of gastrointestinal symptoms. The development of immunodeficiency-associated enteropathy after prolonged viral infections was described in sporadic cases. Clinical consequences of viral gut infections in immunocompromised hosts comprise isolation issues and supportive care. Prospective studies in cohorts of immunodeficient patients are required to study the impact of prolonged enteric viral replication with respect to the pathogenesis of non-infectious enteropathy.

Crosstalk between B lymphocytes, microbiota and the intestinal epithelium governs immunity versus metabolism in the gut

Using a systems biology approach, we discovered and dissected a three-way interaction between the immune system, the intestinal epithelium and the microbiota. We found that, in the absence of B cells, or of IgA, and in the presence of the microbiota, the intestinal epithelium launches its own protective mechanisms, upregulating interferon-inducible immune response pathways and simultaneously repressing Gata4-related metabolic functions. This shift in intestinal function leads to lipid malabsorption and decreased deposition of body fat. Network analysis revealed the presence of two interconnected epithelial-cell gene networks, one governing lipid metabolism and another regulating immunity, that were inversely expressed. Gene expression patterns in gut biopsies from individuals with common variable immunodeficiency or with HIV infection and intestinal malabsorption were very similar to those of the B cell-deficient mice, providing a possible explanation for a longstanding enigmatic association between immunodeficiency and defective lipid absorption in humans.

Inflammatory bowel disease: beyond the boundaries of the bowel

Dysregulated inflammation in the gut, designated clinically as inflammatory bowel disease (IBD), is manifested by the prototypic phenotypes of an Arthus-like reaction restricted to the mucosa of the colon, as in ulcerative colitis, or a transmural granulomatous reaction, as in Crohn's disease, or an indeterminate form of the two polar types. That the inflammation of IBD can trespass the boundaries of the bowel has long been known, with articular, ophthalmologic, cutaneous, hepatobiliary or other complications/associations - some autoimmune and others not - affecting significant numbers of patients with IBD. Also notable is the frequency of diagnosis of IBD-type diseases on a background of systemic, (mostly myelo-hematological) disorders, associated with alterations of either (or both) innate or adaptive arms of the immune response. Finally, cases of IBD are reported to occur as an adverse effect of TNF inhibitors. Bone marrow transplant has been proven to be the only curative measure for some of the above cases. Thus, in effect, the IBDs should now be regarded as a systemic, rather than bowel-localized, disease. Genome-wide association studies have been informative in consolidating the view of three phenotypes of IBD (ulcerative colitis, Crohn's disease and mixed) and, notably, are revealing that the onset of IBD can be linked to polymorphisms in regulatory miRNAs, or to nucleotide sequences coding for regulatory lymphokines and/or their receptors. At the effector level, we emphasize the major role of the Th17/IL-23 axis in dictating the perpetuation of intestinal inflammation, augmented by a failure of physiological control by regulatory T-cells. In conclusion, there is a central genesis of the defects underlying IBD, which therefore, in our opinion, is best accommodated by the concept of IBD as more of a syndrome than an autonomous disease. This altered mindset should upgrade our knowledge of IBD, influence its medical care and provide a platform for further advances.

Intestinal microbiota, evolution of the immune system and the bad reputation of pro-inflammatory immunity

The mammalian intestine provides a unique niche for a large community of bacterial symbionts that complements the host in digestive and anabolic pathways, as well as in protection from pathogens. Only a few bacterial phyla have adapted to this predominantly anaerobic environment, but hundreds of different species create an ecosystem that affects many facets of the host's physiology. Recent data show how particular symbionts are involved in the maturation of the immune system, in the intestine and beyond, and how dysbiosis, or alteration of that community, can deregulate immunity and lead to immunopathology. The extensive and dynamic interactions between the symbionts and the immune system are key to homeostasis and health, and require all the blends of so-called regulatory and pro-inflammatory immune reactions. Unfortunately, pro-inflammatory immunity leading to the generation of Th17 cells has been mainly associated with its role in immunopathology. Here we discuss the view that the immune system in general, and type 17 immunity in particular, develop to maintain the equilibrium of the host with its symbionts.

Inflammatory bowel diseases in patients with adaptive and complement immunodeficiency disorders

Crohn's disease and ulcerative colitis are idiopathic chronic inflammatory diseases that primarily affect the gastrointestinal tract. The underlying causes remain poorly understood, but there is a growing body of evidence advocating a likely primary pathogenic role for immunodeficiency in the development of Crohn's lesions. Concordantly, a number of congenital immunodeficiencies disrupting the cellular innate immune system strongly predispose to noninfectious, Crohn's-like inflammatory bowel disease. There are case reports and series suggesting that the same may be true for some of the congenital adaptive and complement immunodeficiencies. This review considers and critiques these potential associations.

The role of secretory antibodies in infection immunity

The mucosal secretory immune system provides an important primary defence against disease, as studies of humans with mucosal humoral immunodeficiencies suggest that the absence of secretory immunoglobulin A leads to an increase in mucosal infections. However, the infection risks posed do not seem to provide the evolutionary drive to retain constitutive secretion of often 'hard won' protein, suggesting that secretory antibodies may have some other important function (or functions). This Review examines the evidence that secretory antibodies provide an important defence against infection in specific animal models and explores complementary explanations for the evolution of the secretory immune system.

How I treat common variable immune deficiency

Common variable immunodeficiency is a rare immune deficiency, characterized by low levels of serum immunoglobulin G, A, and/or M with loss of antibody production. The diagnosis is most commonly made in adults between the ages of 20 and 40 years, but both children and older adults can be found to have this immune defect. The range of clinical manifestations is broad, including acute and chronic infections, inflammatory and autoimmune disease, and an increased incidence of cancer and lymphoma. For all these reasons, the disease phenotype is both heterogeneous and complex. Contributing to the complexity is that patient cohorts are generally small, criteria used for diagnosis vary, and the doses of replacement immune globulin differ. In addition, routines for monitoring patients over the years and protocols for the use of other biologic agents for complications have not been clarified or standardized. In the past few years, data from large patient registries have revealed that both selected laboratory markers and clinical phenotyping may aid in dissecting groups of subjects into biologically relevant categories. This review presents my approach to the diagnosis and treatment of patients with common variable immunodeficiency, with suggestions for the use of laboratory biomarkers and means of monitoring patients.

Spectrum of clinical presentations in familial hemophagocytic lymphohistiocytosis type 5 patients with mutations in STXBP2

Hemophagocytic lymphohistiocytosis (HLH) is an often-fatal hyperinflammatory syndrome characterized by fever, hepatosplenomegaly, cytopenia, and in some cases hemophagocytosis. Here, we describe the mutation analysis, clinical presentation, and functional analysis of natural killer (NK) cells in patients with mutations in STXBP2 encoding Munc18-2, recently associated with familial HLH type 5. The disease severity among 11 persons studied here was highly variable and, accordingly, age at diagnosis ranged from 2 months to 17 years. Remarkably, in addition to typical manifestations of familial HLH (FHL), the clinical findings included colitis, bleeding disorders, and hypogammaglobulinemia in approximately one-third of the patients. Laboratory analysis revealed impairment of NK-cell degranulation and cytotoxic capacity. Interleukin-2 stimulation of lymphocytes in vitro rescued the NK cell-associated functional defects. In conclusion, familial HLH type 5 is associated with a spectrum of clinical symptoms, which may be a reflection of impaired expression and function of Munc18-2 also in cells other than cytotoxic lymphocytes. Mutations in STXBP2 should thus also be considered in patients with clinical manifestations other than those typically associated with HLH.