Background/Aims: Very early-onset inflammatory bowel disease (VEO-IBD), defined as IBD diagnosed in patients younger than 6 years, is a challenge for pediatric gastroenterologists. Although there have been reports regarding VEO-IBD in Western countries, those in Asia are still lacking. This study aimed to investigate the clinical features of Japanese VEO-IBD patients.Methods: Patients with VEO-IBD diagnosed between 2006 and 2019 were evaluated retrospectively. The disease phenotypes were classified into ulcerative colitis type (UC-type) and Crohn’s disease type (CD-type), and the clinical features and courses were compared between the phenotypes.Results: Overall, 54 VEO-IBD patients (19 patients with UC-type and 35 patients with CD-type) were evaluated. The median age at onset was 18 months. One patient had severe combined immunodeficiency (SCID), and 9 patients had monogenic IBD. Monogenic IBD was more prevalent in the CD-type patients with perianal disease (CD-type (PD)). The age at onset was significantly lower in the CD-type group (P<0.05). The most common initial symptom was bloody stools (70%), followed by diarrhea (63%), weight loss (24%), fever (20%), and perianal disease (20%). Excluding patients with SCID and monogenic IBD, 23 out of 44 patients (52%) required biologics. The biologics were switched in 11 out of 44 patients (25%), and the majority of these patients (82%) were in the CD-type group. Overall, 9 patients (20%) required intestinal resection or ostomy placement.Conclusions: CD-type tends to occur at an earlier age, and monogenic IBD occurs significantly more frequently in CD-type (PD). Disease severity and treatment should be individualized, owing to the disease heterogeneity.

The penetration of allergens through the epithelial layer is the initial step in the development of allergic conjunctivitis. Although pollinosis patients manifest symptoms within minutes after pollen exposure, the mechanisms of the rapid transport of the allergens remain unclear. In the present study, we found that the instillation of pollen shells rapidly induces a large number of goblet cell–associated antigen passages (GAPs) in the conjunctiva. Antigen acquisition by stromal cells, including macrophages and CD11b ⁺ dendritic cells, correlated with surface GAP formation. Furthermore, a substantial amount of antigen was transported to the stroma during the first 10 minutes of pollen exposure, which was sufficient for the full induction of an allergic conjunctivitis mouse model. This inducible, rapid GAP formation and antigen acquisition were suppressed by topical lidocaine or trigeminal nerve ablation, indicating that the sensory nervous system plays an essential role. Interestingly, pollen shell–stimulated GAP formation was not suppressed by topical atropine, suggesting that the conjunctival GAPs and intestinal GAPs are differentially regulated. These results identify pollen shell–induced GAP as a therapeutic target for allergic conjunctivitis.

Evidence relating to the efficacy of Helicobacter pylori eradication therapy for chronic immune thrombocytopenic purpura (cITP) in childhood is inadequate. The aim of this retrospective study was to determine the efficacy of H. pylori eradication therapy for platelet response in pediatric patients with cITP in our hospital, and to perform a systematic review of previous reports about pediatric patients with cITP who were positive for H. pylori infection and were treated with H. pylori eradication therapy. Analysis of the data of pediatric patients with cITP in our hospital and a systematic review of digital literature databases of studies in pediatric patients with cITP were performed. Data of 33 pediatric patients with cITP from our hospital records showed that the prevalence of H. pylori infection and the rate of response to platelet therapy were 15% and 33.3%, respectively. Data of 706 pediatric patients from 18 previous reports showed that the prevalence of H. pylori infection and rate of platelet response were 23% and 43.8%, respectively. Eradication therapy for H. pylori infection in pediatric cITP patients can be expected to result in a response equivalent to that in the adult population, with fewer adverse effects than other treatments for cITP.

The efficacy of the COVID-19 mRNA vaccine, including the third vaccination in pediatric inflammatory bowel disease (PIBD) patients is not fully understood. This study aimed to evaluate the humoral immunogenicity of the BNT162b2 vaccine and the changes in durability until 20–28 weeks after the initial vaccine series in PIBD patients on immunosuppressive drugs. The safety of the initial vaccine series and the booster effect of the third vaccination were also evaluated. A single-center, prospective cohort study was conducted, and 63 participants (anti-TNFα: 11; non-anti-TNFα: 31; 5-ASA: 21), with a mean age of 15.2 (range 9.6–17.9) years, were enrolled. All PIBD patients were seroconverted, with no serious short-term AEs. PIBD patients on anti-TNFα had significantly lower antibody titers than those on other medications at all measurement points. Furthermore, antibody titers waned over time with anti-TNFα and were significantly lower at 20–28 weeks than at 3–9 weeks after a two-vaccine series. In all 10 patients (anti-TNFα: 5; non-anti-TNFα including 5-ASA: 5), the third vaccination led to antibody concentrations significantly higher than those at the same time point after the second vaccination. PIBD patients on anti-TNFα need to remain vigilant about COVID-19 even after two vaccinations, and a third vaccination may be considered.

Juvenile polyps, typically localized in the rectum and sigmoid colon, are a common cause of pediatric bloody stool. An isolated small intestinal juvenile polyp is uncommon and generally difficult to diagnose. The first case of an isolated juvenile polyp diagnosed by abdominal ultrasonography before acute abdomen had developed and resected by double-balloon endoscopy is presented along with a review of previous reports including this case. A two-year-old Japanese boy was referred to our institute for further evaluation of anemia persisting from one year of age. Laboratory findings showed mild iron deficiency anemia and elevated fecal human hemoglobin (Hb) and fecal calprotectin values. Upper and lower endoscopic findings showed no abnormalities. Because the abdominal ultrasonography performed one year later demonstrated a 15 mm jejunal polyp, combined with a similar finding on small intestinal capsule endoscopy, this was diagnosed as an isolated lesion. The lesion was resected by cautery with double-balloon endoscopy and diagnosed as a juvenile polyp pathologically. All clinical symptoms disappeared, and all laboratory data improved after treatment, without recurrence for more than one year after the procedure. Abdominal ultrasonographic screening and the fecal calprotectin value led to the diagnosis and non-surgical invasive treatment of an isolated small intestinal juvenile polyp.

Fecal surrogate markers strongly correlate with endoscopic findings in pediatric onset inflammatory bowel disease: a retrospective study in Japan