**Figure 6.** Figure 1. Vitamin D and barrier function in the gastrointestinal tract. Schematic representation of the expression of the vitamin D receptor (VDR) and vitamin D-activating enzyme (CYP27B1) in human colonic epithelial cells, antigen presenting cells such as dendritic cells (DC), and T cells. Immune responses to vitamin D occur either via systemic 1,25-dihydroxyvitamin D (1,25-(OH)2D) or local conversion of 25-hydroxyvitamin D (25-OH-D) to 1,25-(OH)2D. Possible target mechanisms include: 1) interface with microbiota (induction of antibacterials such as angiogenin, cathelcidin (LL37), defensins or intracellular pathogen recognition proteins such as nucleotide-binding oligomerisation domain containing 2 (NOD2)); 2) T cell homing to sites of inﬂammation; 3) suppression of inﬂammatory Th17 and Th1 cells and induction of tolerogenic Treg and Th2 cells; 4) enhanced expression of epithelial membrane junction proteins

Description

Vitamin D receptor expression and vitamin D-activating enzyme CYP27B1 are present in human colonic epithelial cells, enabling local production of active calcitriol. This paracrine signaling enhances tight junction integrity and antimicrobial defense at the mucosal surface.

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Figure 5

Animal models of colitis demonstrate that vitamin D deficiency exacerbates intestinal inflammation, while supplementation or VDR activation attenuates disease severity. These findings support a mechanistic link between vitamin D status and IBD pathophysiology.

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Figure 6

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Source Paper

The Role of Vitamin D in Inflammatory Bowel Disease: Mechanism to Management.

Nutrients (2019)

PMID: 31067701

DOI: 10.3390/nu11051019

Cite This Figure

![Figure 6: Vitamin D receptor expression and vitamin D-activating enzyme CYP27B1 are present in human colonic epithelial cells, enabling local production of active calcitriol. This paracrine signaling enhances tight junction integrity and antimicrobial defense at the mucosal surface.](https://pdfs.citedhealth.com/figures/31067701/110.png)

> Source: Jane Fletcher et al. "The Role of Vitamin D in Inflammatory Bowel Disease: Mechanism to Management.." *Nutrients*, 2019. PMID: [31067701](https://pubmed.ncbi.nlm.nih.gov/31067701/)

<figure>
  <img src="https://pdfs.citedhealth.com/figures/31067701/110.png" alt="Vitamin D receptor expression and vitamin D-activating enzyme CYP27B1 are present in human colonic epithelial cells, enabling local production of active calcitriol. This paracrine signaling enhances tight junction integrity and antimicrobial defense at the mucosal surface." />
  <figcaption>Figure 6. Vitamin D receptor expression and vitamin D-activating enzyme CYP27B1 are present in human colonic epithelial cells, enabling local production of active calcitriol. This paracrine signaling enhances tight junction integrity and antimicrobial defense at the mucosal surface.<br>  Source: Jane Fletcher et al. "The Role of Vitamin D in Inflammatory Bowel Disease: Mechanism to Management.." <em>Nutrients</em>, 2019. PMID: <a href="https://pubmed.ncbi.nlm.nih.gov/31067701/">31067701</a></figcaption>
</figure>

Related Evidence

Vitamin D for Inflammatory Bowel Disease (IBD) — General

Grade B · 10 studies