Pediatric inflammatory bowel disease: continuous lessons for adult inflammatory bowel disease

Pregnancy-Onset Ulcerative Colitis in a Pediatric Patient Presenting With Altered Mental Status and Severe Anemia

Ulcerative colitis (UC) classically presents with abdominal pain, hematochezia, or diarrhea. However, it can present atypically in pediatric and pregnant patients, posing a diagnostic challenge. A healthy, 16-year-old primigravida presented at 18 weeks and six days of gestation with sudden-onset altered mental status and severe anemia. Hematochezia began about 12 hours after admission. She underwent extensive workup, leading to an endoscopic and histopathologic diagnosis of UC, and achieved prenatal remission with high-dose steroids and infliximab. Her pregnancy, however, was complicated by severe preeclampsia, and her child’s post-delivery course was medically complex from an unrelated etiology. Pregnancy-onset inflammatory bowel disease (IBD) in the pediatric population is an uncommon but important consideration. Early diagnosis, treatment, and counseling are vital to achieve results comparable to those of patients without IBD.

Gut Microbiome and Organ Fibrosis

Fibrosis is a pathological process associated with most chronic inflammatory diseases. It is defined by an excessive deposition of extracellular matrix proteins and can affect nearly every tissue and organ system in the body. Fibroproliferative diseases, such as intestinal fibrosis, liver cirrhosis, progressive kidney disease and cardiovascular disease, often lead to severe organ damage and are a leading cause of morbidity and mortality worldwide, for which there are currently no effective therapies available. In the past decade, a growing body of evidence has highlighted the gut microbiome as a major player in the regulation of the innate and adaptive immune system, with severe implications in the pathogenesis of multiple immune-mediated disorders. Gut microbiota dysbiosis has been associated with the development and progression of fibrotic processes in various organs and is predicted to be a potential therapeutic target for fibrosis management. In this review we summarize the state of the art concerning the crosstalk between intestinal microbiota and organ fibrosis, address the relevance of diet in different fibrotic diseases and discuss gut microbiome-targeted therapeutic approaches that are current being explored.

Fine tuning of the DNAM-1/TIGIT/ligand axis in mucosal T cells and its dysregulation in pediatric inflammatory bowel diseases (IBD)

De-regulated T-cell activation and functions are pivotal in the orchestration of immune-mediated tissue damage in IBD. We investigated the role of DNAM-1 (co-activating)/TIGIT (co-inhibitory)/ligand axis in the regulation of T-cell functions and its involvement in IBD pathogenesis. We show that DNAM-1 and TIGIT display a peculiar expression pattern on gut mucosa T-cell populations, in a microenvironment where their shared ligands (PVR and Nectin-2) are physiologically present. Moreover, DNAM-1 family receptor/ligand system is perturbed in IBD lesions, in a disease activity-dependent manner. The expression profile of CCR6 and CD103 mucosa addressins suggests that microenvironment-associated factors, rather than skewed recruitment of circulating T-cell populations, play a more relevant role in supporting the establishment of DNAM-1 and TIGIT expression pattern in mucosal T-cell populations, and may explain its alteration in IBD. Although both co-receptors mark functionally competent T cells, DNAM-1 and TIGIT segregate on T cells endowed with different proliferative potential. Moreover, their opposing role in regulating T-cell proliferation exquisitely depends on ligand availability. All together, our data propose a role for DNAM-1 and TIGIT in regulating mucosal T-cell activation and immune homeostasis, and highlight the involvement of an imbalance of this system in IBD.