Serum IgG4 Subclass Deficiency Defines a Distinct, Commonly Encountered, Severe Inflammatory Bowel Disease Subtype

Case report and review of literature: IgG4-gastroduodenitis in upper GI Crohn's disease: two separate entities or just a marker of disease severity?

A 20-year-old man was presented with ulcerative gastritis and duodenitis complicated by pyloric stenosis. Helicobacter pylori infection was excluded, and the lesions did not respond to treatment with proton pump inhibitors. No other parts of the intestinal tract showed signs of inflammation. Histopathological review showed signs of chronic inflammation with granuloma formation. A tentative diagnosis of isolated upper gastrointestinal (UGI) Crohn's disease was performed. However, additional work-up revealed significantly positive IgG4 staining as well as elevated IgG4 serum levels. Since granulomatous disease is unlikely in IgG4-related disease, an eventual diagnosis of overlapping IgG4-related disease and Crohn's disease (CD) was performed. Treatment with systemic steroids and anti-TNF in combination with azathioprine led to rapid symptomatic improvement. In this article, we review the available literature on IgG4-related gastroduodenitis, granulomatous gastritis, and upper GI CD. We suggest the possibility that IgG4-infiltration may be a marker of severely active inflammatory bowel disease rather than a separate disease entity.

The unique properties of IgG4 and its roles in health and disease

IgG4 is the least abundant subclass of IgG in human serum and has unique functional features. IgG4 is largely unable to activate antibody-dependent immune effector responses and, furthermore, undergoes Fab (fragment antigen binding)-arm exchange, rendering it bispecific for antigen binding and functionally monovalent. These properties of IgG4 have a blocking effect, either on the immune response or on the target protein of IgG4. In this Review, we discuss the unique structural characteristics of IgG4 and how these contribute to its roles in health and disease. We highlight how, depending on the setting, IgG4 responses can be beneficial (for example, in responses to allergens or parasites) or detrimental (for example, in autoimmune diseases, in antitumour responses and in anti-biologic responses). The development of novel models for studying IgG4 (patho)physiology and understanding how IgG4 responses are regulated could offer insights into novel treatment strategies for these IgG4-associated disease settings.

Crohn's Disease-Like Features in a Patient With IgE and Selective IgG1 and IgG3 Deficiency

We report a 19-year-old male with congenital, combined deficiency of immunoglobulin (Ig) E and 2/4 subclasses of IgG (G1, G3) and chronic diarrhea. He presented at six years of age with chronic recurrent diarrhea responsive to immunoglobulin treatment. Initially, it was considered of infectious origin. However, at the age of 14 years, ileocolonoscopy and magnetic resonance enterography (MRE) were performed, and they showed a mild, limited, non-specific, terminal ileitis with increased eosinophil count on histology. A diagnosis of possible eosinophilic gastroenteritis was made, and budesonide was administered with temporary relief. However, at the age of 19 years, repeat ileocolonoscopy showed multiple ulcers in the terminal ileum and aphthous ulcers in the cecum, and repeat MRE demonstrated extensive ileal involvement. Esophagogastroduodenoscopy demonstrated the involvement of the upper GI tract with aphthous ulcers. Subsequently, gastric, ileal, and colonic biopsies revealed Ziehl-Neelsen-negative, non-caseating granulomas. We hereby report the first case of IgE and selective IgG1 and IgG3 deficiency complicated with Crohn's disease-like extensive GI involvement.

Diagnosis of inflammatory bowel disease according to human IgG4 and possibilities of evaluating efficacy of the therapy

Taking into account the progress of understanding diagnosis, course prognosis, evaluation of effectiveness of therapy of inflammatory bowel disease and also differentiation diagnosis between its main forms – ulcerative colitis and Crohn’s disease, the search for efficient non-invasive markers for solving those issues is extremely relevant. The patients were divided into groups depending on nosology and severity of the course of the disease. All the patients had undergone endoscopic study for diagnosis verification and biopsy samples were taken for further detection of tissue IgG4 using the immunohistochemical method. Also, we determined concentration of serum IgG4. Increase in IgG4content in blood serum was determined in 54.0% of the cases of inflammatory bowel disease. Concentration of IgG4 in patients suffering ulcerative colitis was higher (by 2.31 and 2.46 times) compared with its level in the control group and patients with Crohn’s disease, respectively. We found relationships between the concentration of serum IgG4 and the activity of the disease. In patients with ulcerative colitis, increased tissue IgG4 was found more often than in patients with Crohn’s disease (by 2.77 times, Р < 0.05). We determined the relationship between tissue IgG4 and histological activity. Simultaneous increase in serum IgG4 and presence of tissue IgG4 during ulcerative colitis were more frequent than during Crohn’s disease (by 2.66 times). In all examined groups of patients, we determined decrease in serum IgG4 content (by 1.66 times) after treatment. Concentration of serum IgG4 and positive tissue IgG4 in ulcerative colitis patients exceeded such in Crohn’s disease patients, which may be used for differentiation diagnosis between those disease types. We determined dependence of IgG4 concentration on severity and duration of the disease, which could be used as a prognostic marker. Decrease in IgG4 content in blood serum against the background of the therapy shows that this indicator could be used as a marker of treatment efficacy. Perspectives of further studies are as follows: parameters of concentration of serum IgG4 and presence of tissue IgG4 could be used as diagnostic and prognostic biomarkers and be introduced to practice for differentiation diagnosis between ulcerative colitis and Crohn’s disease, and could be used as prognostic marker of severity of the disease and therapy efficacy.

Association of Serum Immunoglobulins Levels With Specific Disease Phenotypes of Crohn's Disease: A Multicenter Analysis in China

Background and Aim: Serum immunoglobulins were reported to be associated with clinical characteristics of inflammatory bowel disease. However, whether a difference exists in the serum immunoglobulins levels in patients with Crohn's disease (CD) with different disease location and behavior phenotypes remains unclear. Therefore, this study aimed to explore the associations of serum immunoglobulins levels with specific CD phenotypes. Methods: Patients with CD having recorded serum immunoglobulins levels were recruited through multicenter collaborative efforts. The associations between serum immunoglobulins levels and distinct phenotypes of CD were evaluated using multiple logistic regression models. Results: A total of 608 patients with CD were included in the study. Elevated (above the upper limit of normal) serum immunoglobulin G (IgG), IgA, IgM, and IgG4 were identified in 24.5, 17.4, 2.1, and 8.2% of patients, respectively. Elevated serum IgG4 levels negatively correlated with complicated disease behavior [odds ratio (OR) 0.49, 95% confidence interval (CI) 0.26-0.92]. Elevated serum IgG was linked to isolated ileal disease with an OR of 0.37 (95% CI 0.23-0.61). The ORs of isolated ileal disease progressively reduced across increasing quartiles of IgG (P for trend < 0.001). The adjusted ORs of isolated ileal disease for increasing quartiles of IgM were 1.82 (1.07-3.1), 1.92 (1.14-3.24), 1.17 (0.69-1.98), and 1 (P for trend = 0.008). Besides, serum IgA and IgG levels significantly correlated with several disease activity indices. Conclusions: These results suggested that certain serum immunoglobulins were associated with specific disease phenotypes of CD. Further investigations to account for the associations are warranted.