X-linked inhibitor of apoptosis protein deficiency complicated with Crohn's disease-like enterocolitis and Takayasu arteritis: A case report

A pilot study of childhood-onset Takayasu arteritis using whole exome sequencing suggests oligogenic inheritance involving classical complement, collagen, and autoinflammatory pathways

Takayasu arteritis (TA) is a chronic granulomatous inflammatory disease affecting the aorta and its branches. Paediatric TA (pTA) may present from 6 months after birth till the adolescent age group. Genetics and pathogenesis of pTA are not fully understood. Earlier studies reported monogenic mutation in NOD2, XIAP, and STAT1 genes in patients with pTA. TA, a relatively rare disease, is more common in geographical pockets, including India. We hypothesized that South Asian patients with pTA, namely, those of Indian subcontinent origin, may have clinically relevant and unique pathogenic variants involving one or more genes, especially those linked to genetically driven vasculitic illnesses, including autoinflammatory pathologies. Children with pTA fulfilling EULAR/PRINTO/PReS classification criteria and presenting with clinical symptoms to the Paediatric Rheumatology clinic of Christian Medical College, Vellore, were included. Blood samples were collected after getting informed consent from parents or guardians and assent forms from children. DNA was extracted from whole blood using the Qiagen DNA extraction kit. Initially, the common variant in Indian population, namely, ADA2 c.139G > A; p.Gly47Arg, was screened, followed by whole exome sequencing. Fourteen children were recruited for the study. Median age of patients was 11 years (4 months-14 years) with a male-to-female ratio of 4:10. Distribution of angiographic subsets by Numano's classification of included children were as follows: type 5 (n = 7), type 4 (n = 5), and type 3 (n = 2). We identified novel variants in ten different genes. This include variants in genes of classical complement pathway, namely, C2, C3, C6, C7, and C9, and other genes, namely, CYBA, SH3BP2, GUCY2C, CTC1, COL5A1, and NLPR3. Two of 14 patients have heterozygous pathogenic variants; this implies that combination of heterozygous variants in C3 and COL5A1 might lead to disease development, suggesting digenic inheritance. One patient has a homozygous variant in CYBA. None of the patients were identified to have ADA2 variants. Whole exome sequencing reveals combination of rare variants in genes C3, COL5A1, and CYBA associated with disease development in children with Takayasu Arteritis. Key Points • We identified novel variants in genes of classical complement pathway, namely, C2, C3, C6, C7, and C9, and other genes, namely, CYBA, SH3BP2, GUCY2C, CTC1, COL5A1, and NLPR3. • Two of 14 patients have heterozygous pathogenic variants in C3 and COL5A1; this may have implications in disease development, suggesting digenic inheritance. • One patient has homozygous variant in CYBA. • None of the patients were identified to have ADA2 variants.

Takayasu's arteritis associated with Crohn's disease treated with infliximab

A 23-year-old woman presented with fever, diarrhea, bloody stools, and arthralgia that did not improve despite previous treatments and was diagnosed with Crohn's disease. Remission was achieved after the introduction of infliximab, nutritional therapy, and 5-aminosalicylic acid treatment. However, the patient's blood sedimentation rate remained elevated without symptom recurrence, except for abdominal pain in the following year. Aortic wall thickening in the thoracic descending aorta was also observed on computed tomography. Accumulation in the thoracic descending aorta and abdominal aorta was confirmed using positron emission tomography-computed tomography. The patient was diagnosed with Takayasu's arteritis. The patient's abdominal symptoms resolved, and her blood sedimentation rate normalized after steroid administration.

Novel XIAP mutation with early-onset Crohn's disease complicated with acute heart failure: a case report

BACKGROUND

The X-linked inhibitor of apoptosis (XIAP) protein is encoded by the XIAP gene and is critical for multiple cell responses and plays a role in preventing cell death. XIAP mutations are associated with several diseases, primarily including hemophagocytic lymphohistiocytosis and inflammatory bowel disease (IBD). We report the clinical features and results associated with hemizygous mutation of the XIAP gene in a young male with Crohn's disease complicated with acute heart failure.This 16-year-old patient ultimately died of heart failure.

CASE PRESENTATION

A young male of 16 years of age was initially diagnosed with Crohn's disease based on evidences from endoscopic and histological findings. Although supportive care, anti-infective drugs and biologics were administered consecutively for 11 months, his clinical manifestations and laboratory indices (patient's condition) did not improved. Additionally, the patient exhibited a poor nutritional status and sustained weight loss. Subsequently, acute heart failure led to the exacerbation of the patient's condition. He was diagnosed with wet beriberi according to thiamine deficiency, but the standard medical therapy for heart failure and thiamine supplementation did not reverse the adverse outcomes. Comprehensive genetic analysis of peripheral blood-derived DNA revealed a novel hemizygous mutation of the XIAP gene (c.1259_1262 delACAG), which was inherited from his mother.

CONCLUSION

A novel XIAP mutation (c.1259_1262 delACAG) was identified in this study. It may be one of the potential pathogenic factors in Crohn's disease and plays an important role in the progression of heart failure. Additionally, thiamine deficiency triggers a vicious cycle.

Intestinal outcome of bone marrow transplantation for monogenic inflammatory bowel disease

BACKGROUND

Some monogenic inflammatory bowel diseases (IBDs) are known to be refractory to conventional treatments. Although allogeneic hematopoietic stem-cell transplantation (allo-HSCT) has become a curative therapeutic option for certain monogenic IBDs, its effectiveness regarding endoscopic improvements has not been clarified.

METHODS

The clinical course and endoscopic findings of patients with monogenic IBDs who were treated with allo-HSCT between December 2017 and November 2018 at the National Center for Child Health and Development, were retrospectively reviewed. The clinical disease activity was assessed using the weighted Pediatric Crohn's Disease Activity Index (wPCDAI) and the endoscopic finding was evaluated using the Simple Endoscopic Score for Crohn's Disease (SES-CD). Clinical remission was defined as a wPCDAI <10 and endoscopic remission was defined as an SES-CD of 2 or less.

RESULTS

Four patients with severe monogenic IBDs, including three with X-linked inhibitors of apoptosis protein (XIAP) deficiency and one with interleukin-10 signaling defect, were treated with allo-HSCT with reduced-intensity conditioning. In four patients, the maximum scores of wPCDAI and SES-CD before allo-HSCT ranged from 67.5 to 120 and 20 to 34, respectively. After allo-HSCT, all four patients showed a significant improvement in intestinal inflammation and achieved both clinical and endoscopic remission. Although patients with XIAP deficiency presented with post-transplant hemophagocytic lymphohistiocytosis and a relatively late engraftment, all patients achieved prolonged clinical remission, and IBD medications were successfully discontinued in all patients.

CONCLUSION

Allo-HSCT for monogenic IBD resulted in complete clinical resolution with endoscopically confirmed mucosal healing.

An Update on Childhood-Onset Takayasu Arteritis

Takayasu Arteritis (TAK) is a rare large vessel vasculitis affecting the aorta and its major branches. The heterogeneous and often severe clinical manifestations result from systemic and local inflammation as well as end-organ ischemia. Disease flares are common and contribute to accrued damage over time with significant morbidity and mortality. Newer understanding of the pathogenesis in TAK has paved the way for the use of pathway targeting agents such as tumor necrosis factor (TNF)α- or interleuking (IL)-6-inhibitors with improved disease control. Nevertheless, long-term data are lacking, particularly in children; prognosis often remains guarded and the disease burden high. This article aims at providing a comprehensive review of childhood-onset TAK with a focus on recent publications.

Phenotype, genotype, treatment, and survival outcomes in patients with X-linked inhibitor of apoptosis deficiency

BACKGROUND

X-linked inhibitor of apoptosis (XIAP) deficiency is a rare, primary immunodeficiency disease caused by XIAP gene mutations. A broad range of phenotype, severity, and age of onset present challenges for patient management.

OBJECTIVE

To characterize the phenotype, treatment, and survival outcomes of XIAP deficiency and assess parameters influencing prognosis.

METHODS

Data published from 2006-2020 were retrospectively analyzed.

RESULTS

167 patients from 117 families with XIAP deficiency were reported with 90 different mutations. A wide spectrum of clinical features were seen, of which hemophagocytic lymphohistiocytosis (HLH) and inflammatory bowel disease (IBD) were the most common. Patients frequently developed multiple features with no clear genotype-phenotype correlation. 117 patients were managed conservatively and 50 underwent hematopoietic stem cell transplantation (HSCT), with respective overall survival probabilities of 90% and 53% at age 16 years. The predominant indication for HSCT was early-onset HLH. Active HLH and myeloablative conditioning regimens increased HSCT-related mortality, although HSCT outcome was much better after 2015 than before. For conservatively managed patients reaching adulthood, survival probabilities were 86% at age 30 years and 37% by age 52 years, with worse outcomes for patients developing the disease before the age of 5 years or with new disease features in adulthood. 9 asymptomatic mutation carriers were identified with a median age of 13.5 years.

CONCLUSIONS

Our study demonstrates the variable nature of XIAP deficiency which evolves over life for individual patients. Better therapeutic strategies and prospective studies are required to reduce morbidity and mortality and improve decision-making and long-term outcomes for patients with XIAP deficiency.

Hematopoietic Cell Transplantation Rescues Inflammatory Bowel Disease and Dysbiosis of Gut Microbiota in XIAP Deficiency

BACKGROUND

X-linked inhibitor of apoptosis protein (XIAP) deficiency is an infrequent inborn error of immunity that is often associated with refractory inflammatory bowel disease (IBD). The natural course of XIAP deficiency is typically associated with poor prognosis, and hematopoietic cell transplantation (HCT) is the only curative treatment.

OBJECTIVE

To study (1) the effect of HCT on patients with XIAP deficiency undergoing HCT, (2) the status of XIAP deficiency-associated IBD after HCT, and (3) the gut microbiota of XIAP deficiency-associated IBD before and after HCT.

METHODS

A nationwide survey of patients with XIAP deficiency was conducted. A spreadsheet questionnaire was collected from the physicians. Feces samples collected from the patients before and after HCT and their healthy family members were analyzed.

RESULTS

Twenty-six patients with XIAP deficiency underwent HCT by the end of March 2020, and 22 patients (84.6%) survived. All the survivors underwent a fludarabine-based reduced-intensity condition regimen. Acute graft-versus-host disease was observed in 17 patients (65.4%). Nineteen patients experienced refractory IBD before undergoing HCT. IBD improved remarkably after HCT. After HCT, the colonoscopic and pathological symptoms were restored to normal, and the pediatric ulcerative colitis activity index improved significantly. Gut microbiota indicated dysbiosis before HCT; however, it was improved to resemble that of the healthy family members after HCT.

CONCLUSIONS

This study revealed that HCT has a favorable outcome for XIAP deficiency. HCT rescues gut inflammation and dysbiosis in patients with XIAP deficiency.

Takayasu arteritis in an adolescent with Crohn's disease

Crohn’s disease (CD) and Takayasu arteritis (TA) are two distinct clinical entities. Τhe likelihood of both diseases coexisting is low, and although CD co-occurs with all types of vasculitis, TA is the most common subtype. Herein, the case of a 15-year-old female, diagnosed with TA following an initial diagnosis of CD, is reported. A review of the literature, including a systemic review of the case reports and case series of children and adolescents up to the age of 21, with both CD and TA, follows the case description. In total, 28 cases of TA and CD were retrieved. The median age of patients was 14.8 years, they were mostly females (72%) and the median time between the two diagnoses was 3.7 years. In the majority of cases, CD was diagnosed first and TA followed. Computed tomography angiography and magnetic resonance angiography were the preferred imaging modalities to assist diagnosis.

Evolution of Our Understanding of XIAP Deficiency

X-linked inhibitor of apoptosis (XIAP) deficiency is a rare inborn error of immunity first described in 2006. XIAP deficiency is characterised by immune dysregulation and a broad spectrum of clinical manifestations, including haemophagocytic lymphohistiocytosis (HLH), inflammatory bowel disease (IBD), hypogammaglobulinemia, susceptibility to infections, splenomegaly, cytopaenias, and other less common autoinflammatory phenomena. Since the first description of the disease, many XIAP deficient patients have been identified and our understanding of the disease has grown. Over 90 disease causing mutations have been described and more inflammatory disease manifestations, such as hepatitis, arthritis, and uveitis, are now well-recognised. Recently, following the introduction of reduced intensity conditioning (RIC), outcomes of allogeneic haematopoietic stem cell transplantation (HSCT), the only curative treatment option for XIAP deficiency, have improved. The pathophysiology of XIAP deficiency is not fully understood, however it is known that XIAP plays a role in both the innate and adaptive immune response and in immune regulation, most notably through modulation of tumour necrosis factor (TNF)-receptor signalling and regulation of NLRP3 inflammasome activity. In this review we will provide an up to date overview of both the clinical aspects and pathophysiology of XIAP deficiency.