INTRODUCTION: Iron deficiency and vitamin D deficiency are common comorbidities in inflammatory bowel disease (IBD). Accumulating evidence indicates that active 1,25-dihydroxyvitamin D (1,25(OH)D) may enhance iron absorption by suppressing hepcidin. We investigated the influence of vitamin D on iron metabolism in patients with IBD and on the expression of genes facilitating intestinal epithelial iron absorption. METHODS: Iron parameters and serum levels of 25-hydroxyvitamin D (25(OH)D), 1,25(OH)D, and hepcidin were measured in 104 adult patients with IBD (67 with Crohn's disease and 37 with ulcerative colitis). Genes involved in iron absorption were tested for induction by 1,25(OH)D in Caco-2 cells, which resemble the small intestinal epithelium. RESULTS: In multiple regression models controlling for age, sex, body mass index, smoking status, disease activity, and C-reactive protein levels, low 25(OH)D levels were associated with iron deficiency in patients with IBD (β [SE] = −0.064 [0.030], P = 0.029). Vitamin D sufficiency was associated with increased levels of ferritin (β [SE] = 0.25 [0.11], P = 0.024) and transferrin saturation (β [SE] = 8.41 [4.07], P = 0.044). Higher 1,25(OH)D:25(OH)D ratios were associated with lower hepcidin levels (β [SE] = −4.31 [1.67], P = 0.012). Especially in Crohn's disease, increased 1,25(OH)D correlated with higher transferrin saturation (β [SE] = 0.43 [0.18], P = 0.027). Furthermore, 1,25(OH)D strongly induced the expression of the ferroxidase ceruloplasmin in Caco-2 cells. DISCUSSION: Low vitamin D levels in IBD correlate with iron deficiency. Vitamin D may ameliorate iron deficiency, potentially by downregulating hepcidin and upregulating ceruloplasmin, enhancing intestinal iron absorption.

Recently updated COVID-19 mRNA vaccines encode the spike protein of the omicron subvariant XBB.1.5 and are recommended for patients with inflammatory bowel disease (IBD) on immunosuppressive treatment. Nonetheless, their immunogenicity in patients with IBD against rapidly expanding virus variants remains unknown. This prospective multicenter cohort study is the first study to investigate the immunogenicity of XBB.1.5-adapted vaccines in patients with IBD. Systemic and mucosal antibodies targeting the receptor-binding domains (RBDs) of the omicron subvariants XBB.1.5, EG.5.1, and BA.2.86, as well as their neutralization were quantified before and two to four weeks after vaccination with monovalent XBB.1.5-adapted mRNA vaccines. Vaccination increased levels of serum anti-RBD IgG targeting XBB.1.5, EG.5.1, and BA.2.86 (1.9-fold, 1.8-fold, and 2.6-fold, respectively) and enhanced corresponding neutralization responses (2.3-fold, 3.1-fold, and 3.5-fold, respectively). Following vaccination, anti-TNF-treated patients had reduced virus neutralization compared to patients on treatments with other cellular targets. 11.1% and 16.7% of patients lacked EG.5.1 and BA.2.86 neutralization, respectively; all these patients received anti-TNF treatment. At mucosal sites, vaccination induced variant-specific anti-RBD IgG but failed to induce RBD-targeting IgA. Our findings provide a basis for future vaccine recommendations while highlighting the importance of frequent booster vaccine adaptation and the need for mucosal vaccination strategies in patients with IBD.

Background: Bilberries are effective in inducing clinical, endoscopic, and biochemical improvement in ulcerative colitis (UC) patients. The aim of this study was to investigate the efficacy of anthocyanin-rich extract (ACRE), the bioactive ingredient of bilberries, in a controlled clinical trial in moderate-to-severe UC. Methods: A multi-center, randomized, placebo-controlled, double-blind study with a parallel group was conducted. Initially, the study was planned for 100 patients; nevertheless, it prematurely ended due to COVID-19. Patients had moderate-to-severe active UC at screening (a Mayo score of 6–12, an endoscopic sub-score ≥ 2) and were randomized at baseline. The primary endpoint was a clinical response (week 8, a total Mayo score reduction ≥ 3 points). Fecal calprotectin (FC) and a centrally read endoscopic response were among the secondary endpoints. Results: Out of 48 patients (6 Swiss centers), 34 were randomized. Eighteen ACRE and eight placebo patients could be analyzed (per protocol set). Half (9/18) of ACRE patients and 3/8 of placebo patients responded clinically (p = 0.278). An improvement in the Mayo score was observed in the ACRE arm (77.8% vs. 62.5% placebo). FC dropped from 1049 ± 1139 to 557 ± 756 μg/g for ACRE but not for the placebo group (947 ± 1039 to 1040 ± 1179; p = 0.035). Serious adverse events were rare. Conclusions: ACRE treatment did not yield significant superiority to the placebo. Furthermore, the placebo response was unusually high. Moreover, there was a significant calprotectin decrease at the end of treatment, indicative of ACRE efficacy in UC.