How would serum 25(OH)D level change in patients with inflammatory bowel disease depending on intestinal mucosa vitamin D receptor (VDR) and vitamin D1-α hydroxylase (CYP27B1)?

Role of Cytochromes P450 in Intestinal Barrier Function: Possible Involvement in the Pathogenesis of Leaky Gut Syndrome

The intestinal barrier constitutes the largest surface of the human body communicating with the external environment. Alterations affecting elements of intestinal wall may lead to increased intestinal permeability and resulting translocation of bacteria or its components to the bloodstream in the form of the "leaky gut syndrome" (LGS). One of the most common causes of LGS is the disruption of tight junctions (TJ) maintained by tight junction proteins (TJP). LGS and associated alterations in TJP are observed in numerous gastrointestinal (GI) diseases, including inflammatory bowel diseases (IBD) such as Crohn's disease (CD) and ulcerative colitis (UC). Current literature indicates the key role of LGS in many pathological processes, further emphasizing the need for effective pharmacological approaches to treat this syndrome. One of the potential pharmacological targets in LGS treatment are members of the cytochrome P450 (CYP450) superfamily. By affecting intestinal permeability, they may lead to LGS development. It was found that the expression of CYP8B1 synthesizing cholic acid and CYP26 degrading all-trans retinoic acid indirectly influence TJs. CYP2E1 responsible for the metabolism of a wide variety of chemicals, including ethanol, plays a crucial role in the impairment of the intestinal wall. Contrarily, the overexpression of CYP27B1 has a protective effect on the intestinal integrity. CYP1A1, CYP2A6, CYP2J2 and CYP3A were also suggested to influence the GI tract, through their capability to metabolize serotonin, nicotine, endocannabinoids and gemcitabine, respectively. This review summarizes the findings on the role of CYP450 isoforms in intestinal hyperpermeability and their potential involvement in the pathophysiology of LGS.

The correlation between serum 25-hydroxyvitamin D level and ulcerative colitis: a systematic review and meta-analysis

OBJECTIVE

The incidence of UC has increased yearly. Many studies have suggested that patients with ulcerative colitis have abnormal vitamin D levels. A systematic review and meta-analysis were conducted to investigate the association between vitamin D levels and ulcerative colitis.

METHODS

We searched PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang and China Science and Technology Journal Database (VIP) from inception to December 2022. We included case-control studies comparing the differences in vitamin D levels between patients with ulcerative colitis and healthy populations. Meta-analysis was performed using Review Manager5.4, Stata17.0 and other software.

RESULTS

Sixteen eligible observational studies were selected from 473 articles involving 2234 subjects, and they included 987 patients with ulcerative colitis and 1247 controls. The results showed that the serum level of vitamin D in patients with ulcerative colitis was significantly lower than that in healthy controls (SMD = -0.83, 95% CI: -1.18, -0.48). Vitamin D deficiency was reported in five studies. The prevalence of vitamin D deficiency was significantly higher in the ulcerative colitis group than in the healthy control group (OR = 1.90, 95% CI: 1.38, 2.62).

CONCLUSION

Serum vitamin D levels were significantly lower in patients with ulcerative colitis than in healthy controls.

Bile acids and their receptors: Potential therapeutic targets in inflammatory bowel disease

Chronic and recurrent inflammatory disorders of the gastrointestinal tract caused by a complex interplay between genetics and intestinal dysbiosis are called inflammatory bowel disease. As a result of the interaction between the liver and the gut microbiota, bile acids are an atypical class of steroids produced in mammals and traditionally known for their function in food absorption. With the development of genomics and metabolomics, more and more data suggest that the pathophysiological mechanisms of inflammatory bowel disease are regulated by bile acids and their receptors. Bile acids operate as signalling molecules by activating a variety of bile acid receptors that impact intestinal flora, epithelial barrier function, and intestinal immunology. Inflammatory bowel disease can be treated in new ways by using these potential molecules. This paper mainly discusses the increasing function of bile acids and their receptors in inflammatory bowel disease and their prospective therapeutic applications. In addition, we explore bile acid metabolism and the interaction of bile acids and the gut microbiota.

The Potential of Vitamin D3 to Repaired Mucosal Injury in Dextran Sulfate Sodium Induced Acute Colitis in Mice

BACKGROUND: Inflammatory Bowel Disease (IBD) has become an emerging disease worldwide. The treatment of IBD involves two basic principles: Inflammation control and mucosal repair. AIM: This study evaluates the potential effect of Vitamin D3 in mucosal repair through colon stem cell activation and proliferation. METHODS: Dextran sulfate sodium (DSS; 5%) was used to induce colitis in mice. Vitamin D3 at various dosages was then administered as a treatment. The mice were divided into five groups: Control (C-); DSS only (C+); and DSS (5%) plus Vitamin D3 at 0.2 μg (VD1), 0.4 μg (VD2), or 0.6 μg (VD3) per 25 g body weight as the treatment groups. Immunofluorescence analyses of Lgr5+ expression indicated stem cell activation, and Ki67 expression indicated stem cell proliferation. The disease activity index (DAI), colon length, and histopathological index scores were determined after treatment to assess the inflammation and severity of colitis. RESULTS: Immunofluorescence analyses showed a gradually increasing expression of Lgr5+ also Ki67 in proportion with high doses group of Vitamin D3 (p < 0.05). The colon length, DAI scores, and histopathological index scores improved in all groups after Vitamin D3 treatment (p = 0.05; p = 0.026; and p = 0.029, respectively). CONCLUSION: Vitamin D3 has a potential beneficial effect on amplifying intestinal stem cells regulated by Wnt/B-catenin signaling. It is also reduced the inflammatory process proved by the evaluation severity of colitis. It might play an essential role in mucosal repair in IBD.

The Role of Vitamin D in the Pathogenesis of Inflammatory Bowel Disease

Vitamin D has a complex role in the pathogenesis of inflammatory bowel disease (IBD), which is still under investigation. We conducted a literature search using PubMed through December 2018 through the use of relevant search terms. We found an abundance of evidence to support the role of vitamin D in regulating the innate and adaptive arms of the immune system. The pathogenesis of IBD implicates the immune dysregulation of these immune system components. Proof of concept of the vitamin’s role in the pathogenesis of IBD is the mapping of the vitamin D receptor in a region of chromosome 12, where IBD is also mapped, and specific VDR polymorphisms’ link to IBD phenotypes. Further research is needed to better delineate vitamin D’s role in preventing IBD and its potential as a therapeutic target for this disease.

Vitamin D in Inflammatory Bowel Disease: Biological, Clinical and Therapeutic Aspects

BACKGROUND

Vitamin D has an immunoregulatory action in Inflammatory Bowel Disease (IBD) as well as other immune-mediated disorders. Its influence on intestinal permeability, innate and adaptive immunity, and the composition and diversity of the microbiota contribute to the maintenance of intestinal homeostasis. Patients with IBD have a greater prevalence of vitamin D deficiency than the general population, and a possible association between this deficit and a worse course of the disease. However, intervention studies in patients with IBD have proved inconclusive.

OBJECTIVE

To review all the evidence concerning the role of vitamin D as an important factor in the pathophysiology of IBD, review the associations found between its deficiency and the prognosis of the disease, and draw conclusions for the practical application from the main intervention studies undertaken.

METHODS

Structured search and review of basic, epidemiological, clinical and intervention studies evaluating the influence of vitamin D in IBD, following the basic principles of scientific data.

RESULTS

Vitamin D deficiency is associated with disease activity, quality of life, the consumption of social and healthcare resources, and the durability of anti-TNFα biological treatment. Determination of new metabolites of vitamin D, measurement of its absorption capacity and questionnaires about sun exposure could help identify groups of IBD patients with a special risk of vitamin D deficiency.

CONCLUSION

Well-designed intervention studies are needed in IBD, with probably higher objective plasma doses of vitamin D to establish its efficacy as a therapeutic agent with immunomodulatory properties. Meanwhile, vitamin D deficiency should be screened for and corrected in affected patients in order to achieve adequate bone and phosphocalcic metabolism.