INTRODUCTION: Collagenous gastritis (CG), a rare disorder of unknown etiology, has been postulated to have immune-mediated mechanisms. We investigated (i) the incidence and prevalence of CG in a pediatric population; (ii) the clinical, endoscopic, and histologic characteristics of childhood-onset CG; and (iii) the evidence for autoimmunity and/or inflammatory activity in these patients. METHODS: Clinical, endoscopic, and histologic data were reviewed longitudinally in a population-based Swedish cohort of 15 patients with childhood-onset CG diagnosed in the period 2008–2019. A set of 11 autoantibodies, 4 blood inflammatory biomarkers, and the human leukocyte antigen DQ2/DQ8 genotype was analyzed cross-sectionally. RESULTS: The incidence rate of childhood-onset CG was 0.25/100,000 person-years, with an incidence rate ratio of girls to boys of 4.2 (95% confidence interval, 1.2–15). The prevalence of CG was 2.1/100,000 in children aged younger than 18 years. The endoscopic and histologic findings remained pathologic in all the examined patients during a median follow-up of 4.4 years. Many patients had heredity for autoimmune disorders (47%) and/or tested positive for autoantibodies (40%) or human leukocyte antigen DQ2/DQ8 (53%). No associated autoimmune comorbidities were observed. The serum levels of calprotectin and amyloid A were increased in 10/15 (67%) and 5/15 (33%) of the patients, respectively, whereas plasma C-reactive protein levels were normal in all, but 1 patient. DISCUSSION: The results indicate that childhood-onset CG is rare and has a chronic disease course. Although signs of autoimmune predisposition are frequent, early development of autoimmune comorbidities seems seldom. Serum calprotectin and amyloid A represent novel candidate biomarkers of inflammatory activity in CG (see Visual Abstract, Supplementary Digital Content 4, http://links.lww.com/CTG/A349 ).

Children with EoE can be distinguished from healthy children based on the molecular patterns of their blood eosinophils. Age-related physiologic differences in eosinophil molecular patterns may partly explain the different blood eosinophil phenotypes in children vs adults with EoE.

Background. Allergy and other immune-mediated diseases are more frequently reported in children who have undergone liver transplantation. Furthermore, autoantibodies are also prevalent, suggesting a state of immune dysregulation in these patients. Whether or not these processes occur simultaneously in the same individual has not been studied previously. Methods. A cohort of 43 children who had undergone liver transplantation for nonautoimmune liver disease at median age of 1.3 years was investigated for allergy and autoimmune disease. Sensitization to food and inhalant allergens was assessed, and autoantibodies were measured. Results. The prevalence of food allergy was 26% and that of respiratory allergy was 23%, whereas 33% and 26% of the subjects were sensitized to food and inhalant allergens, respectively. Autoimmune disease (ie, autoimmune hepatitis) occurred in a single individual (2%), whereas autoantibodies were present in 44% of the children. Food allergy and autoantibodies occurred concomitantly in 19% of the children, which was almost twice the frequency expected by chance (11%, P = 0.04). Respiratory allergy and the presence of autoantibodies were unrelated (12% concurrence versus the expected 10%, P = 0.73). In the logistic regression analysis, autoantibody formation was associated with discontinued immunosuppression and food allergy, with odds ratios of 13 (P = 0.01) and 7.1 (P = 0.03), respectively. Conclusions. In contrast to respiratory allergy, food allergy and autoantibody formation occurred together in the same children who underwent liver transplantation at a frequency higher than would be expected by chance. This may reflect an underlying immune dysregulation that impairs immune tolerance to both food allergens and autoantigens.