Persistent systemic inflammation and atypical enterocolitis in patients with NEMO syndrome

Competency of Jeffrey Modell Foundation warning signs and routine laboratory tests in suspecting primary immunodeficiencies: A cross-sectional multi-centric prospective study from eastern India

AIM

To test the efficaciousness of the 10 warning signs of Jeffrey Modell Foundation (JMF) and routine laboratory tests in predicting Primary Immunodeficiencies (PIDs).

METHODS

Hospitalized children <12 years age satisfying at least two of 10 warning signs were subjected to routine and confirmatory tests.

RESULTS

Of 35 204 admitted patients, 66 satisfied the JMF criteria and 34 had PID. Also, 59% were infants, with a female preponderance. The most common immunodeficiency disorder group were antibody deficiencies and phagocyte defects (35.3%). Chronic granulomatous disease (CGD) was the commonest overall (29.4%). The need for intravenous antibiotics was the most sensitive (91%) criterion for predicting PID. When combined with positive family history of PID, sensitivity (94%) increased further. The two most specific indicators were recurrent ear infections (88%), and family history of PID (88%). The best positive predictor was family history of PID (69%), and the best negative predictor was recurrent sinus infections (58%). Significant association was found between persistent oral thrush and PID (p .043), and insufficient weight gain and antibody deficiencies (p .037). Absolute neutrophil count, CRP, and elevated ESR were also significantly associated with PIDs (p-values being .036, .011, and .014 respectively).

CONCLUSION

Out of all 10 JMF criteria, the three most important ones to predict PID were need for IV antibiotics, family history of PID, and recurrent ear infections.

An Atypical Incontinentia Pigmenti Female with Persistent Mucocutaneous Hyperinflammation and Immunodeficiency Caused by a Novel Germline IKBKG Missense Mutation

While most missense mutations of the IKBKG gene typically result in Ectodermal Dysplasia with Immunodeficiency, there have been rare reported instances of missense mutations of the IKBKG gene causing both Incontinentia Pigmenti (IP) and immunodeficiency in female patients. In this study, we described an atypical IP case in a 19-year-old girl, characterized by hyperpigmented and verrucous skin areas over the entire body. Remarkably, she experienced recurrent red papules whenever she had a feverish upper respiratory tract infection. Immunohistochemical staining unveiled a substantial accumulation of CD68+ macrophages alongside the TNF-α positive cells in the dermis tissue of new pustules, with increased apoptotic basal keratinocytes in the epidermis tissue of these lesions. Starting from the age of 8 years old, the patient suffered from severe and sustained chronic respiratory mucous membrane scar hyperplasia and occluded subglottic lumen. In addition to elevated erythrocyte sedimentation rate values, inflammatory cells were observed in the pathologic lesions of endobronchial biopsies and Bronchoalveolar Lavage Fluid (BALF) smear. Further histological analysis revealed a destructive bronchus epithelium integrity with extensive necrosis. Simultaneously, the patient experienced recurrent incomplete intestinal obstructions and lips contracture. The patient's BALF sample displayed an augmented profile of proinflammatory cytokines and chemokines, suggesting a potential link to systemic hyperinflammation, possibly underlying the pathogenic injuries affecting the subglottic, respiratory, and digestive systems. Furthermore, the patient presented with recurrent pneumonias and multiple warts accompanied by a T+BlowNKlow immunophenotype. Next generation sequencing showed that the patient carried a novel de novo germline heterozygous missense mutation in the IKBKG gene (c. 821T>C, p. L274P), located in the highly conserved CC2 domain. TA-cloning sequencing of patient's cDNA yielded 30 mutant transcripts out of 44 clones. In silico analysis indicated that the hydrogen bond present between Ala270 and Leu274 in the wild-type NEMO was disrupted by the Leu274Pro mutation. However, this mutation did not affect NEMO expression in peripheral blood mononuclear cells (PBMCs). Moreover, patient PBMCs exhibited significantly impaired TNF-α production following Lipopolysaccharide (LPS) stimulation. X-chromosome inactivation in T cells and neutrophils were not severely skewed. Reduced levels of IκBα phosphorylation and degradation in patient's PBMCs were observed. The NF-κB luciferase reporter assay conducted using IKBKG-deficient HEK293T cells revealed a significant reduction in NF-kB activity upon LPS stimulation. These findings adds to the ever-growing knowledge on female IP that might contribute to the better understanding of this challenging disorder.

NF-kappa-B essential modulator (NEMO) gene polymorphism in an adult woman with systemic lupus erythematosus and recurrent non-tuberculous mycobacterial disseminated infections

Infections are among the most serious complications in patients with systemic lupus erythematosus (SLE), with bacterial and viral infections being the most common. Non-tuberculous mycobacterial (NTM) infections are quite rare and are typically seen in older patients with SLE with longstanding disease duration treated with corticosteroids. Here, we describe a 39-year-old woman with SLE and an unusual pattern of recurrent NTM disseminated infections. After excluding the presence of autoantibodies against interferon-γ, whole exome sequencing revealed a homozygous polymorphism in the NF-kappa-B essential modulator (NEMO) gene. Primary immunodeficiencies should be included in the differential diagnosis of patients with recurrent opportunistic infections, even in those with iatrogenic immunosuppression.

Clinical Features and Genetic Analysis of Taiwanese Primary Immunodeficiency Patients with Prolonged Diarrhea and Monogenetic Inflammatory Bowel Disease

PURPOSE

Diarrhea lasting longer than 14 days which fails to respond to conventional management is defined as severe and protracted diarrhea and might overlap with inflammatory bowel disease (IBD).

METHODS

The prevalence, associated pathogens, and prognosis of severe and protracted diarrhea without IBD (SD) and with monogenetic IBD (mono-IBD) in primary immunodeficiency patients (PID) were investigated in Taiwan.

RESULTS

A total of 301 patients were enrolled between 2003 and 2022, with predominantly pediatric-onset PID. Of these, 24 PID patients developed the SD phenotype before prophylactic treatment, including Btk (six), IL2RG (four), WASP, CD40L, gp91 (three each), gp47, RAG1 (one each), CVID (two), and SCID (one) without identified mutations. The most detectable pathogens were pseudomonas and salmonella (six each), and all patients improved after approximately 2 weeks of antibiotic and/or IVIG treatments. Six (25.0%) mortalities without HSCT implementation were due to respiratory failure from interstitial pneumonia (3 SCID and 1 CGD), intracranial hemorrhage (WAS), and lymphoma (HIGM). In the mono-IBD group, seventeen patients with mutant TTC7A (2), FOXP3 (2), NEMO (2), XIAP (2), LRBA (1), TTC37 (3), IL10RA (1), STAT1 (1), ZAP70 (1), PIK3CD (1), and PIK3R1 (1) genes failed to respond to aggressive treatments. Nine mono-IBD patients with TTC7A (2), FOXP3 (2), NEMO (2), XIAP (2), and LRBA (1) mutations were fatal in the absence of HSCT. The mono-IBD group had a significantly earlier age of diarrhea onset (1.7 vs 33.3 months, p = 0.0056), a longer TPN duration (34.2 vs 7.0 months, p < 0.0001), a shorter follow-up period (41.6 vs 132.6 months, p = 0.007), and a higher mortality rate (58.9 vs 25.0%, p = 0.012) compared with the SD group.

CONCLUSION

When compared to those with the SD phenotype, the mono-IBD patients had significant early-onset and poor responses to empiric antibiotics, IVIG, and steroids. Anti-inflammatory biologics and suitable HSCT still have the potential to control or even cure the mono-IBD phenotype.

Defects of the Innate Immune System and Related Immune Deficiencies

The innate immune system is the host's first line of defense against pathogens. Toll-like receptors (TLRs) are pattern recognition receptors that mediate recognition of pathogen-associated molecular patterns. TLRs also activate signaling transduction pathways involved in host defense, inflammation, development, and the production of inflammatory cytokines. Innate immunodeficiencies associated with defective TLR signaling include mutations in NEMO, IKBA, MyD88, and IRAK4. Other innate immune defects have been associated with susceptibility to herpes simplex encephalitis, viral infections, and mycobacterial disease, as well as chronic mucocutaneous candidiasis and epidermodysplasia verruciformis. Phagocytes and natural killer cells are essential members of the innate immune system and defects in number and/or function of these cells can lead to recurrent infections. Complement is another important part of the innate immune system. Complement deficiencies can lead to increased susceptibility to infections, autoimmunity, or impaired immune complex clearance. The innate immune system must work to quickly recognize and eliminate pathogens as well as coordinate an immune response and engage the adaptive immune system. Defects of the innate immune system can lead to failure to quickly identify pathogens and activate the immune response, resulting in susceptibility to severe or recurrent infections.

Paradoxical immunodeficiencies-When failures of innate immunity cause immunopathology

Innate immunity facilitates immediate defense against invading pathogens throughout all organs and tissues but also mediates tissue homeostasis and repair, thereby playing a key role in health and development. Recognition of pathogens is mediated by germline-encoded PRRs. Depending on the specific PRRs triggered, ligand binding leads to phagocytosis and pathogen killing and the controlled release of immune-modulatory factors such as IFNs, cytokines, or chemokines. PRR-mediated and other innate immune responses do not only prevent uncontrolled replication of intruding pathogens but also contribute to the tailoring of an effective adaptive immune response. Therefore, hereditary or acquired immunodeficiencies impairing innate responses may paradoxically cause severe immunopathology in patients. This can occur in the context of, but also independently of an increased microbial burden. It can include pathogen-dependent organ damage, autoinflammatory syndromes, and neurodevelopmental or neurodegenerative diseases. Here, we discuss the current state of research of several different such immune paradoxes. Understanding the underlying mechanisms causing immunopathology as a consequence of failures of innate immunity may help to prevent life-threatening disease.

Low Density Granulocytes and Dysregulated Neutrophils Driving Autoinflammatory Manifestations in NEMO Deficiency

NF-κB essential modulator (NEMO, IKK-γ) deficiency is a rare combined immunodeficiency caused by mutations in the IKBKG gene. Conventionally, patients are afflicted with life threatening recurrent microbial infections. Paradoxically, the spectrum of clinical manifestations includes severe inflammatory disorders. The mechanisms leading to autoinflammation in NEMO deficiency are currently unknown. Herein, we sought to investigate the underlying mechanisms of clinical autoinflammatory manifestations in a 12-years old male NEMO deficiency (EDA-ID, OMIM #300,291) patient by comparing the immune profile of the patient before and after hematopoietic stem cell transplantation (HSCT). Response to NF-kB activators were measured by cytokine ELISA. Neutrophil and low-density granulocyte (LDG) populations were analyzed by flow cytometry. Peripheral blood mononuclear cells (PBMC) transcriptome before and after HSCT and transcriptome of sorted normal-density neutrophils and LDGs were determined using the NanoString nCounter gene expression panels. ISG15 expression and protein ISGylation was based on Immunoblotting. Consistent with the immune deficiency, PBMCs of the patient were unresponsive to toll-like and T cell receptor-activators. Paradoxically, LDGs comprised 35% of patient PBMCs and elevated expression of genes such as MMP9, LTF, and LCN2 in the granulocytic lineage, high levels of IP-10 in the patient's plasma, spontaneous ISG15 expression and protein ISGylation indicative of a spontaneous type I interferon (IFN) signature were observed, all of which normalized after HSCT. Collectively, our results suggest that type I IFN signature observed in the patient, dysregulated LDGs and spontaneously activated neutrophils, potentially contribute to tissue damage in NEMO deficiency.

Skin and Mucosal Manifestations in NEMO Syndrome: A Case Series and Literature Review

OBJECTIVES

To characterize the skin and mucosal findings of NEMO syndrome.

METHODS

Retrospective review of clinical characteristics from a cohort of two families with mutations in IKBKG (the NEMO-encoding gene). A literature review identified 86 studies describing 192 patients with IKBKG mutations whose data were also included.

SETTING

Single center with literature review.

PARTICIPANTS

Patients with mutations in IKBKG from our center and reported in the literature.

MAIN OUTCOMES AND MEASURES

Skin and mucosal characteristics of patients with NEMO syndrome.

RESULTS

In addition to ectodermal dysplasia and recurrent infections, male patients had findings of ichthyosis, palmoplantar keratoderma, and inflammatory skin diseases. Both male and female patients had mucocutaneous ulcers and slow-to-heal chronic wounds. In combination with patients from the literature, 59% (85/144) of males had ectodermal dysplasia with anhidrosis (EDA) features, and 8% and 10% (12/144; 6/63) of males and females had dental findings, respectively. 4% (6/144) of males and 32% (20/63) of females had mucocutaneous ulcers. Ichthyosis/xerosis was present in 15% of males (21/144) but only 2% (1/63) females. Similarly, 13% (18/144) of male patients presented with dermatitis while this was reported in only 2% (1/63) of females.

CONCLUSIONS

Our results both confirm and expand upon the known spectrum of mucocutaneous findings in NEMO syndrome. Further genetic studies are needed to correlate specific mutations to clinical and morphologic subtypes.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Clinical case of Bloch — Sulzberger syndrome

Purpose.To present a clinical case of Bloch Sulzberger syndrome. Material and methods. The examinations were performed to diagnose the disease: а visual examination of the skin, cytological analysis of the gallbladder fluid, general and biochemical blood tests, genetic research. Results.During a visual examination of the skin, a differential diagnosis was made with infectious dermatitis, toxic-allergic dermatitis, epidermolysis bullosa and linear IgA-dependent dermatosis in children. Crucial in the diagnosis belonged to a genetic study, after which a deletion of exons 410 of the IKBKG gene was detected, which confirmed Bloch Sulzberger syndrome. Conclusion.Newborns with vesicle-bullous rashes entering the neonatal pathology department and observed by neonatologists require a thorough examination, a mandatory consultation of a dermatologist inorder to determine further management tactics.

Very Early Onset Inflammatory Bowel Disease: A Clinical Approach With a Focus on the Role of Genetics and Underlying Immune Deficiencies

Very early onset inflammatory bowel disease (VEO-IBD) is defined as IBD presenting before 6 years of age. When compared with IBD diagnosed in older children, VEO-IBD has some distinct characteristics such as a higher likelihood of an underlying monogenic etiology or primary immune deficiency. In addition, patients with VEO-IBD have a higher incidence of inflammatory bowel disease unclassified (IBD-U) as compared with older-onset IBD. In some populations, VEO-IBD represents the age group with the fastest growing incidence of IBD. There are contradicting reports on whether VEO-IBD is more resistant to conventional medical interventions. There is a strong need for ongoing research in the field of VEO-IBD to provide optimized management of these complex patients. Here, we provide an approach to diagnosis and management of patients with VEO-IBD. These recommendations are based on expert opinion from members of the VEO-IBD Consortium (www.VEOIBD.org). We highlight the importance of monogenic etiologies, underlying immune deficiencies, and provide a comprehensive description of monogenic etiologies identified to date that are responsible for VEO-IBD.

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.

Successful Allogeneic Stem Cell Transplantation in Nuclear Factor-Kappa B Essential Modulator Deficiency Syndrome After Treosulfan-Based Conditioning: A Case Report

BACKGROUND

X-linked EDA-ID1 (ectodermal dysplasia, anhidrotic, with immunodeficiency 1, Online Mendelian Inheritance in Man [OMIM] 300291), or NEMO (nuclear factor kappa B essential modulator) deficiency syndrome, is caused by mutations in the IKBKG/NEMO gene. We report the case of a boy with EDA-ID1 who underwent allogeneic stem cell transplantation.

METHODS

In early infancy, the patient developed an atypical, severe, initial manifestation resembling Omenn syndrome with infections, and he underwent allogeneic stem cell transplantation from an unrelated 9 of 10 HLA matched donor with a mismatch in the DQB1 allele after conditioning with treosulfan, fludarabine, thiotepa, and antithymocyte globulin (Grafalon). The post-transplant period was complicated by cytomegalovirus replication and mild, grade 2 graft vs host disease. Because of NEMO deficiency syndrome-associated enteropathy and continuous weight loss, parenteral nutrition was started and the patient was fed an elemental formula and a gluten-free diet. Over a period of 3 years, the patient had 7 incidents of blood stream infections caused by Staphylococci or gut-derived Gram-negative flora, with 1 incident of septic shock caused by Escherichia coli. The blood stream infection stopped after gastrointestinal tract decontamination was done once per month for 7-day courses alternately with rifaximin, vancomycin, and gentamicin sulfate.

CONCLUSIONS

Patients with NEMO deficiency syndrome require very complex, multidisciplinary care, and immunodeficiency correction can only be observed as one of the critical points in patient care. Developmental problems, enteropathy with the need for intravenous hyperalimentation, and specific interventions for other clinical manifestations of multifaceted syndrome are needed for proper care.

Questionnaire survey on association between preeclampsia and incontinentia pigmenti

AIM

In this study, a questionnaire survey was conducted to find the relationship between preeclampsia (PE) and incontinentia pigmenti (IP).

METHODS

Using a questionnaire survey of 147 women whose children were diagnosed with IP, this study first investigated their clinical manifestations and complications during pregnancy. The manifestations included high blood pressure, proteinuria and edema after 20 weeks of gestation. Women with and without IP were separated into two groups, then analyzed accordingly.

RESULTS

There were 45 mothers with IP in the case group and 102 mothers without IP in the control group. IP mothers who were pregnant with an IP fetus were at higher risk for hypertension, proteinuria, and edema during pregnancy as compared with non-IP mothers that carried an IP fetus. Out of these 147 mothers, 8 mothers with IP and 6 mothers without IP presented with new-onset hypertension during pregnancy (P = 0.024)，7 mothers with IP and 4 mothers without IP presented with new-onset proteinuria during pregnancy (P = 0.013)，and 21 IP mothers and 27 non-IP mothers presented with edema during pregnancy (P = 0.016). Although no statistical difference was observed, mothers in the case group were more likely to develop the above three symptoms concurrently (6.7% vs 2.0%; P = 0.168), and were more likely to be diagnosed with PE (8.9% vs 3.9%; P = 0.249).

CONCLUSION

Our study revealed that the simultaneous occurrence of IP in the mother and fetus increased the likelihood of clinical manifestations associated with PE during pregnancy.

Missense variants in NOX1 and p22phox in a case of very-early-onset inflammatory bowel disease are functionally linked to NOD2

Whole-genome and whole-exome sequencing of individual patients allow the study of rare and potentially causative genetic variation. In this study, we sequenced DNA of a trio comprising a boy with very-early-onset inflammatory bowel disease (veoIBD) and his unaffected parents. We identified a rare, X-linked missense variant in the NAPDH oxidase NOX1 gene (c.C721T, p.R241C) in heterozygous state in the mother and in hemizygous state in the patient. We discovered that, in addition, the patient was homozygous for a common missense variant in the CYBA gene (c.T214C, p.Y72H). CYBA encodes the p22phox protein, a cofactor for NOX1. Functional assays revealed reduced cellular ROS generation and antibacterial capacity of NOX1 and p22phox variants in intestinal epithelial cells. Moreover, the identified NADPH oxidase complex variants affected NOD2-mediated immune responses, and p22phox was identified as a novel NOD2 interactor. In conclusion, we detected missense variants in a veoIBD patient that disrupt the host response to bacterial challenges and reduce protective innate immune signaling via NOD2. We assume that the patient's individual genetic makeup favored disturbed intestinal mucosal barrier function.

Recent Advance in Very Early Onset Inflammatory Bowel Disease

Recent studies on pediatric inflammatory bowel disease (IBD) have revealed that early-onset IBD has distinct phenotypic differences compared with adult-onset IBD. In particular, very early-onset IBD (VEO-IBD) differs in many aspects, including the disease type, location of the lesions, disease behavior, and genetically attributable risks. Several genetic defects that disturb intestinal epithelial barrier function or affect immune function have been noted in these patients from the young age groups. In incidence of pediatric IBD in Korea has been increasing since the early 2000s. Neonatal or infantile-onset IBD develops in less than 1% of pediatric patients. Children with "neonatal IBD" or "infantile-onset IBD" have higher rates of affected first-degree relatives, severe disease course, and a high rate of resistance to immunosuppressive treatment. The suspicion of a monogenic cause of VEO-IBD was first confirmed by the discovery of mutations in the genes encoding the interleukin 10 (IL-10) receptors that cause impaired IL-10 signaling. Patients with such mutations typically presented with perianal fistulae, shows a poor response to medical management, and require early surgical interventions in the first year of life. To date, 60 monogenic defects have been identified in children with IBD-like phenotypes. The majority of monogenic defects presents before 6 years of age, and many present before 1 year of age. Next generation sequencing could become an important diagnostic tool in children with suspected genetic defects especially in children with VEO-IBD with severe disease phenotypes. VEO-IBD is a phenotypically and genetically distinct disease entity from adult-onset or older pediatric IBD.

Very early onset IBD: novel genetic aetiologies

PURPOSE OF REVIEW

To summarize the current understanding and recent advances on the genetic aetiology in the pathogenesis of very early onset inflammatory bowel disease (VEO-IBD).

RECENT FINDINGS

IBD is a chronic disorder of the gastrointestinal tract whose manifestation is a result of complex interactions between genetics, environment, immune system and microbial flora. Over 230 IBD risk loci have been reported in genome wide association studies but the genetic contribution of the majority of these loci in the manifestation of IBD is very low. Patients with VEO-IBD present with a more severe disease than older patients, characterized by poor prognosis and failure of conventional therapy. Recent studies have reported several monogenic diseases with high penetrance that present with IBD and IBD-like intestinal manifestations and overlap with primary immunodeficiencies. Increasing body of evidence supports a prominent role of genetics in the onset of VEO-IBD. New genetic variants and diagnoses in VEO-IBD are reviewed and current challenges in therapy with potential strategy to manage the disease are discussed.

SUMMARY

Functional analysis of the genes implicated in monogenic IBD has increased the understanding of the underlying pathobiological mechanism of the disease. This knowledge can be used to personalize medicine for specific patients, improving the standard of care and quality of life.

Recent advance in very early-onset inflammatory bowel disease

Recent studies on pediatric inflammatory bowel disease (IBD) have revealed that early-onset IBD has distinct phenotypic differences compared with adult-onset IBD. In particular, very early-onset IBD (VEO-IBD) differs in many aspects, including the disease type, location of the lesions, disease behavior, and genetically attributable risks. Neonatal or infantile-onset IBD develops in less than 1% of pediatric patients. Children with infantile-onset IBD have high rates of affected first-degree relatives and severe disease course. The suspicion of a monogenic cause of VEO-IBD was first confirmed by the discovery of mutations in the genes encoding the interleukin 10 (IL-10) receptors that cause impaired IL-10 signaling. Patients with such mutations typically presented with perianal fistulae, shows a poor response to medical management, and require early surgical interventions in the first year of life. To date, 60 monogenic defects have been identified in children with IBD-like phenotypes. The majority of monogenic defects presents before 6 years of age, and many present before 1 year of age. Next generation sequencing could become an important diagnostic tool in children with suspected genetic defects especially in children with VEO-IBD with severe disease phenotypes. VEO-IBD is a phenotypically and genetically distinct disease entity from adult-onset or older pediatric IBD.

Monogenic Intestinal Epithelium Defects and the Development of Inflammatory Bowel Disease

The incidence of inflammatory bowel disease (IBD) is increasing worldwide, most notably in young children. The development of disease is a combination of several factors, including genetics, environment, the microbiota, and immune system. Recently, next-generation sequencing has allowed for the identification of novel genetic causes for intestinal disease, including pediatric inflammatory bowel disease (IBD). These IBD genes can generally be grouped into genes causing either primary immunodeficiency or intestinal epithelial defects (the focus of this review). Most of these genes have been functionally validated with in vitro and/or animal models, and have been demonstrated to cause intestinal disease. Intestinal epithelial IBD genes are of particular interest since they are the least amenable to current therapies; therefore, further research is warranted to develop potential therapies. A number of cellular pathways are impacted with intestinal epithelial IBD genes, including intestinal epithelial cell adhesion and generation of reactive oxygen species. Here, we describe the currently known IBD risk alleles and monogenic causal intestinal epithelial genes, their putative roles in preserving intestinal epithelial cell homeostasis, and their implications for IBD pathophysiology.

Differential diagnosis of inflammatory bowel disease: imitations and complications

Inflammatory bowel disease (IBD) is characterised by episodes of relapse and periods of remission. However, the clinical features, such as abdominal pain, diarrhoea, and rectal bleeding, are not specific. Therefore, the differential diagnosis can include a broad spectrum of inflammatory or infectious diseases that mimic IBD, as well as others that might complicate existing IBD. In this Review, we provide an overview of ileocolitis of diverse causes that are relevant in the differential diagnosis of IBD. We highlight the importance of accurate patient profiling and give a practical approach to identifying factors that should trigger the search for a specific cause of intestinal inflammation. Mimics of IBD include not only infectious causes of colitis-and particular attention is required for patients from endemic areas of tuberculosis-but also vascular diseases, diversion colitis, diverticula or radiation-related injuries, drug-induced inflammation, and monogenic diseases in very-early-onset refractory disease. A superinfection with cytomegalovirus or Clostridium difficile can aggravate intestinal inflammation in IBD, especially in patients who are immunocompromised. Special consideration should be made to the differential diagnosis of perianal disease.

NOX1 loss-of-function genetic variants in patients with inflammatory bowel disease

Genetic defects that affect intestinal epithelial barrier function can present with very early-onset inflammatory bowel disease (VEOIBD). Using whole-genome sequencing, a novel hemizygous defect in NOX1 encoding NAPDH oxidase 1 was identified in a patient with ulcerative colitis-like VEOIBD. Exome screening of 1,878 pediatric patients identified further seven male inflammatory bowel disease (IBD) patients with rare NOX1 mutations. Loss-of-function was validated in p.N122H and p.T497A, and to a lesser degree in p.Y470H, p.R287Q, p.I67M, p.Q293R as well as the previously described p.P330S, and the common NOX1 SNP p.D360N (rs34688635) variant. The missense mutation p.N122H abrogated reactive oxygen species (ROS) production in cell lines, ex vivo colonic explants, and patient-derived colonic organoid cultures. Within colonic crypts, NOX1 constitutively generates a high level of ROS in the crypt lumen. Analysis of 9,513 controls and 11,140 IBD patients of non-Jewish European ancestry did not reveal an association between p.D360N and IBD. Our data suggest that loss-of-function variants in NOX1 do not cause a Mendelian disorder of high penetrance but are a context-specific modifier. Our results implicate that variants in NOX1 change brush border ROS within colonic crypts at the interface between the epithelium and luminal microbes.

Novel Mutations of the Tetratricopeptide Repeat Domain 7A Gene and Phenotype/Genotype Comparison

The gastrointestinal tract contains the largest lymphoid organ to react with pathogenic microorganisms and suppress excess inflammation. Patients with primary immunodeficiency diseases (PIDs) can suffer from refractory diarrhea. In this study, we present two siblings who began to suffer from refractory diarrhea with a poor response to aggressive antibiotic and immunosuppressive treatment after surgical release of neonatal intestinal obstruction. Their lymphocyte proliferation was low, but superoxide production and IL-10 signaling were normal. Candidate genetic approach targeted to genes involved in PIDs with inflammatory bowel disease (IBD)-like manifestation was unrevealing. Whole-genome sequencing revealed novel heterozygous mutations Glu75Lys and nucleotide 520–521 CT deletion in the tetratricopeptide repeat domain 7A (TTC7A) gene. A Medline search identified 49 patients with TTC7A mutations, of whom 20 survived. Their phenotypes included both multiple intestinal atresia (MIA) and combined T and/or B immunodeficiency (CID) in 16, both IBD and CID in 14, isolated MIA in 8, MIA, IBD, and CID complex in 8, and isolated IBD in 3. Of these 98 mutant alleles over-through the coding region clustering on exon 2 (40 alleles), exon 7 (12 alleles), and exon 20 (10 alleles), 2 common hotspot mutations were c.211 G>A (p.E71K in exon 2) in 26 alleles and AAGT deletion in exon 7 (+3) in 10 alleles. Kaplan–Meier analysis showed that those with biallelic missense mutations (p = 0.0168), unaffected tetratricopeptide repeat domains (p = 0.0311), and developing autoimmune disorders (p = 0.001) had a relatively better prognosis. Hematopoietic stem cell transplantation (HSCT) restored immunity and seemed to decrease the frequency of infections; however, refractory diarrhea persisted. Clinical improvement was reported upon intestinal and liver transplantation in a child with CID and MIA of unknown genetic etiology. In conclusion, patients with TTC7A mutations presenting with the very early onset of refractory diarrhea had limit improvement by HSCT or/and tailored immunosuppressive therapy in the absence of suitable intestine donors. We suggest that MIA–CID–IBD disorder caused by TTC7A mutations should also be included in the PID classification of “immunodeficiencies affecting cellular and humoral immunity” to allow for prompt recognition and optimal treatment.

Gastrointestinal manifestations of primary immune deficiencies in children

Primary immune deficiencies (PID) in children are a rare but serious group of genetic disorders of the immune system which apart from the host's defenses, can also affect every system of the human body, including the gastrointestinal tract. In their severe form they can lead to increased susceptibility to serious infections during infancy and even death. In the less severe form, they can present later in childhood or adolescence with subtle signs and symptoms. As PID can often mimic gastrointestinal diseases, children presenting with atypical gastrointestinal disease and/or failure to respond to conventional therapy should be evaluated for an underlying primary immune disorder and initiated appropriate treatment. The current review of the literature will summarize the gastrointestinal manifestations of primary immune deficiencies in children.

Newcomers in paediatric GI pathology: childhood enteropathies including very early onset monogenic IBD

Childhood enteropathies are a group of diseases causing severe chronic (>2-3 weeks) diarrhoea often starting in the first week of life with the potential for fatal complications for the affected infant. Early identification and accurate classification of childhood enteropathies are, therefore, crucial for making treatment decisions to prevent life-threatening complications. Childhood enteropathies are classified into four groups based on the underlying pathology: (i) conditions related to defective digestion, absorption and transport of nutrients and electrolytes; (ii) disorders related to enterocyte differentiation and polarization; (iii) defects of enteroendocrine cell differentiation; and (iv) disorders associated with defective modulation of intestinal immune response. While the intestinal mucosa is usually normal in enteropathies related to congenital transport or enzyme deficiencies, the intestinal biopsy in other disorders may reveal a wide range of abnormalities varying from normal villous architecture to villous atrophy and/or inflammation, or features specific to the underlying disorder including epithelial abnormalities, lipid vacuolization in the enterocytes, absence of plasma cells, lymphangiectasia, microorganisms, and mucosal eosinophilic or histiocytic infiltration. This review intends to provide an update on small intestinal biopsy findings in childhood enteropathies, the "newcomers", including very early onset monogenic inflammatory bowel disease (IBD), in particular, for the practicing pathologist.

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.

Damaging heterozygous mutations in NFKB1 lead to diverse immunologic phenotypes

BACKGROUND

The nuclear factor κ light-chain enhancer of activated B cells (NF-κB) signaling pathway is a key regulator of immune responses. Accordingly, mutations in several NF-κB pathway genes cause immunodeficiency.

OBJECTIVE

We sought to identify the cause of disease in 3 unrelated Finnish kindreds with variable symptoms of immunodeficiency and autoinflammation.

METHODS

We applied genetic linkage analysis and next-generation sequencing and functional analyses of NFKB1 and its mutated alleles.

RESULTS

In all affected subjects we detected novel heterozygous variants in NFKB1, encoding for p50/p105. Symptoms in variant carriers differed depending on the mutation. Patients harboring a p.I553M variant presented with antibody deficiency, infection susceptibility, and multiorgan autoimmunity. Patients with a p.H67R substitution had antibody deficiency and experienced autoinflammatory episodes, including aphthae, gastrointestinal disease, febrile attacks, and small-vessel vasculitis characteristic of Behçet disease. Patients with a p.R157X stop-gain experienced hyperinflammatory responses to surgery and showed enhanced inflammasome activation. In functional analyses the p.R157X variant caused proteasome-dependent degradation of both the truncated and wild-type proteins, leading to a dramatic loss of p50/p105. The p.H67R variant reduced nuclear entry of p50 and showed decreased transcriptional activity in luciferase reporter assays. The p.I553M mutation in turn showed no change in p50 function but exhibited reduced p105 phosphorylation and stability. Affinity purification mass spectrometry also demonstrated that both missense variants led to altered protein-protein interactions.

CONCLUSION

Our findings broaden the scope of phenotypes caused by mutations in NFKB1 and suggest that a subset of autoinflammatory diseases, such as Behçet disease, can be caused by rare monogenic variants in genes of the NF-κB pathway.

Identifying Mutations of the Tetratricopeptide Repeat Domain 37 (TTC37) Gene in Infants With Intractable Diarrhea and a Comparison of Asian and Non-Asian Phenotype and Genotype: A Global Case-report Study of a Well-Defined Syndrome With Immunodeficiency

Syndromic diarrhea/tricho-hepato-enteric syndrome (SD/THE) is a rare, autosomal recessive and severe bowel disorder mainly caused by mutations in the tetratricopeptide repeat domain 37 (TTC37) gene which act as heterotetrameric cofactors to enhance aberrant mRNAs decay. The phenotype and immune profiles of SD/THE overlap those of primary immunodeficiency diseases (PIDs). Neonates with intractable diarrhea underwent immunologic assessments including immunoglobulin levels, lymphocyte subsets, lymphocyte proliferation, superoxide production, and IL-10 signaling function. Candidate genes for PIDs predisposing to inflammatory bowel disease were sequencing in this study. Two neonates, born to nonconsanguineous parents, suffered from intractable diarrhea, recurrent infections, and massive hematemesis from esopharyngeal varices due to liver cirrhosis or accompanying Trichorrhexis nodosa that developed with age and thus guided the diagnosis of SD/THE compatible to TTC37 mutations (homozygous DelK1155H, Fs*2; heterozygous Y1169Ter and InsA1143, Fs*3). Their immunologic evaluation showed normal mitogen-stimulated lymphocyte proliferation, superoxide production, and IL-10 signaling, but low IgG levels, undetectable antibody to hepatitis B surface antigen and decreased antigen-stimulated lymphocyte proliferation. A PubMed search for bi-allelic TTC37 mutations and phenotypes were recorded in 14 Asian and 12 non-Asian cases. They had similar presentations of infantile onset refractory diarrhea, facial dysmorphism, hair anomalies, low IgG, low birth weight, and consanguinity. A higher incidence of heart anomalies (8/14 vs 2/12; P = 0.0344, Chi-square), nonsense mutations (19 in 28 alleles), and hot-spot mutations (W936Ter, 2779-2G>A, and Y1169Ter) were found in the Asian compared with the non-Asian patients. Despite immunoglobulin therapy in 20 of the patients, 4 died from liver cirrhosis and 1 died from sepsis. Patients of all ethnicities with SD/THE with the characteristic triad of T nodosa, hepatic cirrhosis, and intractable enteropathy have low IgG, poor vaccine response and/or decreased antigen-stimulated lymphocyte proliferation. This is now better classified into the subgroup of "well-defined syndromes with immunodeficiency" (the update termed as "combined immunodeficiencies with associated or syndromic features") than "predominantly antibody deficiencies" in the update PIDs classification, and requires optimal interventions.

Transplantation from a symptomatic carrier sister restores host defenses but does not prevent colitis in NEMO deficiency

NF-κB essential modulator (NEMO) deficiency causes ectodermal dysplasia with immunodeficiency in males, while manifesting as incontinentia pigmenti in heterozygous females. We report a family with NEMO deficiency, in which a female carrier displayed skewed X-inactivation favoring the mutant NEMO allele associated with symptoms of Behçet's disease. Hematopoietic stem cell transplantation of an affected boy from this donor reconstituted an immune system with retained skewed X-inactivation. After transplantation no more severe infections occurred, indicating that an active wild-type NEMO allele in only 10% of immune cells restores host defense. Yet he developed inflammatory bowel disease (IBD). While gut infiltrating immune cells stained strongly for nuclear p65 indicating restored NEMO function, this was not the case in intestinal epithelial cells - in contrast to cells from conventional IBD patients. These results extend murine observations that epithelial NEMO-deficiency suffices to cause IBD. High anti-TNF doses controlled the intestinal inflammation and symptoms of Behçet's disease.

Recruitment of A20 by the C-terminal domain of NEMO suppresses NF-κB activation and autoinflammatory disease

Receptor-induced NF-κB activation is controlled by NEMO, the NF-κB essential modulator. Hypomorphic NEMO mutations result in X-linked ectodermal dysplasia with anhidrosis and immunodeficiency, also referred to as NEMO syndrome. Here we describe a distinct group of patients with NEMO C-terminal deletion (ΔCT-NEMO) mutations. Individuals harboring these mutations develop inflammatory skin and intestinal disease in addition to ectodermal dysplasia with anhidrosis and immunodeficiency. Both primary cells from these patients, as well as reconstituted cell lines with this deletion, exhibited increased IκB kinase (IKK) activity and production of proinflammatory cytokines. Unlike previously described loss-of-function mutations, ΔCT-NEMO mutants promoted increased NF-κB activation in response to TNF and Toll-like receptor stimulation. Investigation of the underlying mechanisms revealed impaired interactions with A20, a negative regulator of NF-κB activation, leading to prolonged accumulation of K63-ubiquitinated RIP within the TNFR1 signaling complex. Recruitment of A20 to the C-terminal domain of NEMO represents a novel mechanism limiting NF-κB activation by NEMO, and its absence results in autoinflammatory disease.

Primary Immunodeficiencies and Inflammatory Disease: A Growing Genetic Intersection

Recent advances in genome analysis have provided important insights into the genetic architecture of infectious and inflammatory diseases. The combined analysis of loci detected by genome-wide association studies (GWAS) in 22 inflammatory diseases has revealed a shared genetic core and associated biochemical pathways that play a central role in pathological inflammation. Parallel whole-exome sequencing studies have identified 265 genes mutated in primary immunodeficiencies (PID). Here, we examine the overlap between these two data sets, and find that it consists of genes essential for protection against infections and in which persistent activation causes pathological inflammation. Based on this intersection, we propose that, although strong or inactivating mutations (rare variants) in these genes may cause severe disease (PIDs), their more subtle modulation potentially by common regulatory/coding variants may contribute to chronic inflammation.

Interferon regulatory factor 5 in human autoimmunity and murine models of autoimmune disease

Interferon regulatory factor 5 (IRF5) has been demonstrated as a key transcription factor of the immune system, playing important roles in modulating inflammatory immune responses in numerous cell types including dendritic cells, macrophages, and B cells. As well as driving the expression of type I interferon in antiviral responses, IRF5 is also crucial for driving macrophages toward a proinflammatory phenotype by regulating cytokine and chemokine expression and modulating B-cell maturity and antibody production. This review highlights the functional importance of IRF5 in a disease setting, by discussing polymorphic mutations at the human Irf5 locus that lead to susceptibility to systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease. In concordance with this, we also discuss lessons in IRF5 functionality learned from murine in vivo models of autoimmune disease and inflammation and hypothesize that modulation of IRF5 activity and expression could provide potential therapeutic benefits in the clinic.

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.

Practice parameter for the diagnosis and management of primary immunodeficiency

The American Academy of Allergy, Asthma & Immunology (AAAAI) and the American College of Allergy, Asthma & Immunology (ACAAI) have jointly accepted responsibility for establishing the "Practice parameter for the diagnosis and management of primary immunodeficiency." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

Pathologic Findings in NEMO Deficiency: A Surgical and Autopsy Survey

Hypomorphic mutations in nuclear factor κB (NF-κB) essential modulator (NEMO), encoded by IKBKG, lead to a variable combined immunodeficiency, which puts patients at risk of early death from infectious complications. The spectrum of clinical manifestations includes inflammatory disorders, especially colitis. Because of the multiple complications of NEMO deficiency, a variety of biopsy, excisional, and autopsy materials from these patients may be subject to pathologic examination. Therefore, using samples from a cohort of patients with this disorder, we aimed to survey the pathologic spectrum of NEMO deficiency and search for correlations between specific genotypes and phenotypes. Clinical and laboratory data, mutation analysis, and pathology from 13 patients were examined, including 6 autopsies. No specific genotype-pathology correlation was identified. However, we confirmed an association between ectodermal dysplasia and inflammatory conditions. We found no characteristic pathology to identify patients with NEMO deficiency; therefore, history, physical examination, and specific infections must remain the clues to suggest the diagnosis. Variability among patients and by infection makes the pathologic recognition of NEMO deficiency challenging.

Maintaining intestinal health: the genetics and immunology of very early onset inflammatory bowel disease

Inflammatory bowel disease (IBD) is a multifactoral disease caused by dysregulated immune responses to commensal or pathogenic microbes in the intestine, resulting in chronic intestinal inflammation. An emerging population of patients with IBD occurring before the age of 5 represent a unique form of disease, termed Very Early Onset (VEO)-IBD, which is phenotypically- and genetically-distinct from older-onset IBD. VEO-IBD is associated with increased disease severity, aggressive progression and poor responsiveness to most conventional therapies. Further investigation into the causes and pathogenesis of VEO-IBD will help improve treatment strategies, and may lead to a better understanding of the mechanisms that are essential to maintain intestinal health or provoke the development of targeted therapeutic strategies to limit intestinal disease. Here we discuss the phenotypic nature of VEO-IBD, the recent identification of novel gene variants associated with disease, and functional immunologic studies interrogating the contribution of specific genetic variants to the development of chronic intestinal inflammation.

When it is not inflammatory bowel disease: differential diagnosis

PURPOSE OF REVIEW

Inflammatory bowel diseases (IBDs) represent a heterogeneous entity whose diagnosis is sometimes difficult to ascertain. Many pathological processes may mimic IBD phenotypes. Among the classical differential diagnoses are enteric infections and infestations as well as drug toxicity. However, recently, more specific differential diagnoses have been included, including monogenic causes of gastrointestinal tract inflammation, particularly in young children. The purpose of the present review is to describe the differential diagnosis of IBD, putting it in a specific clinical and demographic context. This differential diagnosis will be discussed specifically for young children, elderly patients, and immunosuppressed patients.

RECENT FINDINGS

We will focus on the most recent findings and concepts, including monogenic diseases in young children, diverticular disease-associated colitis in elderly patients, and toxic colitis in patients receiving immunosuppressants such as mycophenolate mofetil or biologics such as ipilimumab.

SUMMARY

The aim of this review is to alert the clinician dealing with IBD, concerning a series of specific diagnoses that should be recognized because they may require specific treatment, different from the ones of classical idiopathic IBD.

Novel hypomorphic mutation in IKBKG impairs NEMO-ubiquitylation causing ectodermal dysplasia, immunodeficiency, incontinentia pigmenti, and immune thrombocytopenic purpura

NF-κB essential modulator (NEMO) is a component of the IKK complex, which participates in the activation of the NF-κB pathway. Hypomorphic mutations in the IKBKG gene result in different forms of anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID) in males without affecting carrier females. Here, we describe a hypomorphic and missense mutation, designated c.916G>A (p.D306N), which affects our patient, his mother, and his sister. This mutation did not affect NEMO expression; however, an immunoprecipitation assay revealed reduced ubiquitylation upon CD40-stimulation in the patient's cells. Functional studies have demonstrated reduced phosphorylation and degradation of IκBα, affecting NF-κB recruitment into the nucleus. The patient presented with clinical features of ectodermal dysplasia, immunodeficiency, and immune thrombocytopenic purpura, the latter of which has not been previously reported in a patient with NEMO deficiency. His mother and sister displayed incontinentia pigmenti indicating that, in addition to amorphic mutations, hypomorphic mutations in NEMO can affect females.

Molecular mechanisms in genetically defined autoinflammatory diseases: disorders of amplified danger signaling

Patients with autoinflammatory diseases present with noninfectious fever flares and systemic and/or disease-specific organ inflammation. Their excessive proinflammatory cytokine and chemokine responses can be life threatening and lead to organ damage over time. Studying such patients has revealed genetic defects that have helped unravel key innate immune pathways, including excessive IL-1 signaling, constitutive NF-κB activation, and, more recently, chronic type I IFN signaling. Discoveries of monogenic defects that lead to activation of proinflammatory cytokines have inspired the use of anticytokine-directed treatment approaches that have been life changing for many patients and have led to the approval of IL-1-blocking agents for a number of autoinflammatory conditions. In this review, we describe the genetically characterized autoinflammatory diseases, we summarize our understanding of the molecular pathways that drive clinical phenotypes and that continue to inspire the search for novel treatment targets, and we provide a conceptual framework for classification.

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.

Neonatal incontinentia pigmenti: Six cases and a literature review

The aim of this study was to retrospectively analyze the cases of six infants with incontinentia pigmenti (IP) in the Department of Neonates and compare their data with 60 cases of IP reported in the available Chinese literature, in order to determine the clinical characteristics and outcomes of neonatal IP in China. The majority of the cases were located near the eastern and southern coasts of China, and ~98.5% of IP cases occurred within 1 week of birth. The majority of the babies with IP were term infants. Twelve cases had a positive family history of IP. The mothers of 10 patients had a history of recurrent spontaneous abortions, and the mothers of five patients had infectious or autoimmune diseases during pregnancy. Cutaneous manifestations were shown at stage I in 59 cases, at stage II in 28 cases and at stage III in three cases (multiple stages were recorded in certain cases). Neurological changes occurred in 18 cases and ocular changes were observed in 12 cases. The toxoplasmosis, rubella, cytomegalovirus and herpes simplex (TORCH) test showed positive results in three cases; autoantibody positivity was found in three cases and high blood eosinophil levels were observed in 20 cases. Brain scans revealed positive results in 16 cases and complications were observed in 21 cases. Thirty-four cases were followed for 1-6 months, six cases for 7-12 months and 17 cases for 13-84 months. Among these cases, 34 exhibited no evidence of recurrence. Five patients, including one male, succumbed in the long course of the follow-up. Two IP cases persisted after five years of follow-up. The data from the present study may reflect the characteristics of IP in the Chinese population and provide useful information for the diagnosis and treatment of IP by dermatologists and neonatologists.

Evidence for non-neutralizing autoantibodies against IL-10 signalling components in patients with inflammatory bowel disease

Background

Inflammatory bowel disease constitutes a heterogeneous group of conditions, whose aetiology is only partly understood. The prevailing hypothesis on its pathogenesis is that IBD is the result of an inadequate immune response to the resident bacterial flora of the intestine. An autoimmune background, however, has been discussed since the 1950s. Lately, it has been shown that failures in interleukin-10 (IL-10) signalling due to IL-10- and IL-10 receptor (IL-10R) mutations result in IBD. Our study aimed at investigating the existence of inhibitory autoantibodies against IL-10 and IL-10R in IBD patients capable of down-modulating IL-10 signalling thereby mimicking IL-10 or IL-10R deficiency.

Results

Thirteen IBD patients had IgG autoantibodies against IL-10, IL-10RA and/or IL-10RB, and three patients had IgA autoantibodies against IL-10. However, the absolute OD values of the serum antibodies measured by ELISA were low, there was overall no significant difference between patients and controls, and positive sera had no neutralizing activity.

Conclusion

No evidence for an involvement of autoantibodies against IL-10 or IL-10R in the pathogenesis of inflammatory bowel disease could be established.

Very early onset inflammatory bowel disease associated with aberrant trafficking of IL-10R1 and cure by T cell replete haploidentical bone marrow transplantation

PURPOSE

Loss-of-function mutations in IL10 and IL10R cause very early onset inflammatory bowel disease (VEO-IBD). Here, we investigated the molecular pathomechanism of a novel intronic IL10RA mutation and describe a new therapeutic approach of T cell replete haploidentical hematopoietic stem cell transplantation (HSCT).

METHODS

Clinical data were collected by chart review. Genotypes of IL10 and IL10R genes were determined by Sanger sequencing. Expression and function of mutated IL-10R1 were assessed by quantitative PCR, Western blot analysis, enzyme-linked immunosorbent assays, confocal microscopy, and flow cytometry.

RESULTS

We identified a novel homozygous point mutation in intron 3 of the IL10RA (c.368-10C > G) in three related children with VEO-IBD. Bioinformatical analysis predicted an additional 3' splice site created by the mutation. Quantitative PCR analysis showed normal mRNA expression of mutated IL10RA. Sequencing of the patient's cDNA revealed an insertion of the last nine nucleotides of intron 3 as a result of aberrant splicing. Structure-based modeling suggested misfolding of mutated IL-10R1. Western blot analysis demonstrated a different N-linked glycosylation pattern of mutated protein. Immunofluorescence and FACS analysis revealed impaired expression of mutated IL-10R1 at the plasma membrane. In the absence of HLA-identical donors, T cell replete haploidentical HSCT was successfully performed in two patients.

CONCLUSIONS

Our findings expand the spectrum of IL10R mutations in VEO-IBD and emphasize the need for genetic diagnosis of mutations in conserved non-coding sequences of candidate genes. Transplantation of haploidentical stem cells represents a curative therapy in IL-10R-deficient patients, but may be complicated by non-engraftment.

IL-10 in humans: lessons from the gut, IL-10/IL-10 receptor deficiencies, and IL-10 polymorphisms

Inflammatory bowel disease (IBD) represents a heterogeneous group of gastrointestinal disorders, where commensal gut flora provokes an either (a) insufficient or (b) uncontrolled immune response. This results either in a lack of or in excessive inflammation mainly manifesting as Crohn's disease or ulcerative colitis. IBD commonly presents in adolescence and adulthood and often follows a chronic relapsing course. Genetic and/or environmental factors contribute to the failure of gut immune homeostasis. Genome-wide association studies have identified over 160 susceptibility loci associated with IBD, including polymorphisms in interleukin-10 (IL-10). The anti-inflammatory cytokine IL-10 dampens intestinal inflammation and is therefore a good candidate gene for IBD. Polymorphisms in the IL-10 receptor are also associated with ulcerative colitis presenting in early childhood. Moreover, severe infantile enterocolitis resembling Crohn's disease, caused by loss-of-function mutations in IL-10 and IL-10 receptor, is characterised by a very early onset (usually within the first 3 months of life), unresponsiveness to standard treatment including immunosuppressive therapy, and severe perianal disease with abscesses and fistulas. In these patients, inflammation and polymorphic infiltrates are mainly confined to the colon with very little involvement of the small intestine. Ulceration and granulomas, bloody diarrhoea and failure to thrive also occur. Furthermore, patients may suffer from recurrent fever and respiratory infections. Individuals with IL-10 receptor mutations also experience cutaneous folliculitis and arthritis. Hematopoietic stem cell transplantation is currently the only curative therapy.

Monogenic diseases associated with intestinal inflammation: implications for the understanding of inflammatory bowel disease

Inflammatory bowel disease (IBD), encompassing Crohn's disease and ulcerative colitis, has multifactorial aetiology with complex interactions between genetic and environmental factors. Over 150 genetic loci are associated with IBD. The genetic contribution of the majority of those loci towards explained heritability is low. Recent studies have reported an increasing spectrum of human monogenic diseases that can present with IBD-like intestinal inflammation. A substantial proportion of patients with those genetic defects present with very early onset of intestinal inflammation. The 40 monogenic defects with IBD-like pathology selected in this review can be grouped into defects in intestinal epithelial barrier and stress response, immunodeficiencies affecting granulocyte and phagocyte activity, hyper- and autoinflammatory disorders as well as defects with disturbed T and B lymphocyte selection and activation. In addition, there are defects in immune regulation affecting regulatory T cell activity and interleukin (IL)-10 signalling. Related to the variable penetrance of the IBD-like phenotype, there is a likely role for modifier genes and gene-environment interactions. Treatment options in this heterogeneous group of disorders range from anti-inflammatory and immunosuppressive therapy to blockade of tumour necrosis factor α and IL-1β, surgery, haematopoietic stem cell transplantation or gene therapy. Understanding of prototypic monogenic 'orphan' diseases cannot only provide treatment options for the affected patients but also inform on immunological mechanisms and complement the functional understanding of the pathogenesis of IBD.

A red baby should not be taken too lightly

AIM

To identify clinical and laboratory features that can drive the differential diagnosis of a primary immunodeficiency diseases in patients with ectodermal defects.

METHODS

Analysis of selected teaching cases.

RESULTS

We identified four exemplary cases that allowed to point out specific clues.

CONCLUSIONS

A careful evaluation of immune and ectodermal signs is the key to the diagnosis. Therefore, a multidisciplinary approach can lead to diagnosis and to an appropriate treatment in most of the cases.

Clinical outcome in IL-10- and IL-10 receptor-deficient patients with or without hematopoietic stem cell transplantation

BACKGROUND

Inherited deficiencies of IL-10 or IL-10 receptor (IL-10R) lead to immune dysregulation with life-threatening early-onset enterocolitis.

OBJECTIVES

We sought to gather clinical data of IL-10/IL-10R-deficient patients and devise guidelines for diagnosis and management, including hematopoietic stem cell transplantation (HSCT).

METHODS

We enrolled 40 patients with early-onset enterocolitis and screened for mutations in IL10/IL10R using genetic studies, functional studies, or both of the IL-10 signaling pathway. Medical records of IL-10/IL-10R-deficient patients were reviewed and compiled.

RESULTS

Of 40 patients, we identified 7 with novel mutations, predominantly in consanguineous families with more than 1 affected member. IL-10/IL-10R-deficient patients had intractable enterocolitis, perianal disease, and fistula formation. HSCT was carried out in 2 patients with IL-10 deficiency and 1 patient with IL-10R α chain deficiency and proved to be an effective therapy, leading to rapid improvement of clinical symptoms and quality of life.

CONCLUSION

Because the defect in patients with IL-10/IL-10R deficiency resides in hematopoietic lineage cells and their colitis is resistant to standard immunosuppressive therapy, HSCT should be considered early as a potentially curative therapeutic option.

Interleukin-10 and interleukin-10-receptor defects in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disease characterized by abdominal pain, bloody diarrhoea, and malabsorption leading to weight loss. It is considered the result of inadequate control of an excessive reaction of the immune system to the resident flora of the gut. Like other primary immunodeficiencies, IL-10 and IL-10 receptor (IL10R) deficiency present with IBD and demonstrate the sensitivity of the intestine to any changes of the immune system. Both IL-10 and IL10R deficiency cause severe early-onset enterocolitis and can be successfully treated by hematopoietic stem cell transplantation (HSCT).