About My Health Careers Internship MedBlogs Contact us

Vitamin A Balance Influences Protein That Protects Gut Immunity

by Julia Samuel on October 24, 2017 at 12:37 PM
Font : A-A+

Vitamin A Balance Influences Protein That Protects Gut Immunity

Uncontrolled vitamin A metabolism in the gut can cause harmful inflammation. Dietary intake of vitamin A and the levels of the nutrient in the body can influence inflammatory diseases, like Crohn's disease and inflammatory bowel syndromes.

In the Proceedings of the National Academy of Sciences, the researchers described a branching point in the metabolic pathway for vitamin A that hinges on a single protein, called ISX. The pathway starts with beta-carotene--the pigmented nutrient that gives sweet potatoes and carrots their color.


Beta-carotene forms vitamin A in the small intestine. From there, the majority of vitamin A is transported to other tissues to support healthy vision and other functions. Some vitamin A is also used to produce a growth factor for immune cells in the gut. By studying mice genetically modified to lack ISX, the researchers found ISX helps the body balance this process.

The study showed ISX turns on and off genes involved in the pathway based on beta-carotene availability. The protein helps the small intestine shuttle in the right amount of beta-carotene for the body's vitamin A needs, similar to a gatekeeper at a drawbridge. Nearby immune cells rely on this control mechanism to properly respond to foods entering the small intestine.

This maintains an effective barrier against potential foodborne threats. The researchers found that when ISX is absent, immune cells in the small intestine can overreact to beta-carotene-rich diets. Their findings suggest ISX is a key mediator between diet and gut immunity.

Johannes von Lintig, PhD, associate professor of pharmacology at Case Western Reserve School of Medicine, led the study alongside colleagues from the department of pharmacology and the department of molecular biology and microbiology.

"Vitamin A exists in the diet as beta-carotene, which is enzymatically converted by cells lining the intestine. The content of beta-carotene in natural foods is variable and subject to seasonal fluctuations," said Ni Made Airanthi (Ila) Widjaja-Adhi, PhD, lead author of the study. "We describe in this study a mechanism for coping with this fluctuation, to maintain immunity at the intestinal barrier."

The researchers discovered removing ISX ramps up gene expression 200-fold for the enzyme (Bco1) that converts dietary beta-carotene to vitamin A. Because of this, mice without ISX overproduced vitamin A, and began converting it into retinoic acid--a molecule that regulates the activity of many genes, including genes essential for immunity.

This caused localized swelling--inflammation--as immune cells flooded the area and reproduced. Such severe inflammation made mice lacking ISX immunocompromised, and the inflammation spread to the nearby pancreas.

Mice without ISX couldn't control their vitamin A levels. They overproduced vitamin A and drew too many immune cells to the small intestine. "Too much vitamin A can promote inflammatory disease," von Lintig concluded. "In future studies, the ISX-deficient mouse will be a versatile model to study the molecular details of the intriguing interplay between diet and gastrointestinal immunity."

The study positions ISX at an important control point in vitamin A metabolism. According to von Lintig, ISX may also drive the crosstalk between diet and gut immunity in humans.

"Genetic mutations in the ISX gene have been associated with inflammatory disorders such as Crohn's disease. A better understanding of the molecular factors that control gut immunity will aid the development of nutritional intervention strategies to improve health."

Source: Eurekalert

News A-Z
News Category
What's New on Medindia
Woman with Rare Spinal Cord Defect from Birth Sues Doctor
World AIDS Day 2021 - End Inequalities, End AIDS
View all

Medindia Newsletters Subscribe to our Free Newsletters!
Terms & Conditions and Privacy Policy.

More News on:
Calcium and Vitamin Supplements Vitamin Supplements Vitamin C / Ascorbic acid Vitamin B6 Vitamin B9 Vitamin B-12 Vitamin-F Immunisation Amyotrophic Lateral Sclerosis (ALS) Myasthenia Gravis 

Recommended Reading
Vitamin A Supplementation Reduces the Risk of Hearing Loss
High dose vitamin A supplementation in early childhood was found to reduce the risk of hearing loss ...
Vitamin A Rich Foods
Vitamin A rich foods are essential for a variety of body functions. Vitamin A foods can be obtained ...
Foods That Can Make Skin Oily
Wrong food choices and poor skin care contribute to oily skin and acne. Avoiding foods that secrete ...
How is Vitamin A Crucial to Preventing Diabetes?
Cell surface expressed receptor for vitamin A is identified as the key factor for the development .....
Amyotrophic Lateral Sclerosis (ALS)
Find out more about the degenerative disease- Amyotrophic lateral sclerosis....
Calcium and Vitamin Supplements
Calcium and vitamin supplements are taken to provide the body with the ''required'' nutrients. Calci...
Myasthenia Gravis
Myasthenia gravis is the commonest disorder of neuromuscular transmission. Autoimmune myasthenia gra...
Vitamin B-12
Vitamin B-12 is also known as cobalamine or cyanocobalamine, owing to the presence of the metal, cob...
Vitamin B6
Vitamins play an equally important part in the synthesis of neurotransmitters. Neurotransmitters in ...
Vitamin B9
Vital info about vitamin B9, its molecular structure, dietary sources, beneficial aspects, symptoms ...
Vitamin C / Ascorbic acid
Vital info about vitamin C, its molecular structure, dietary sources, beneficial aspects, symptoms o...
Vitamin Supplements
Easy to understand info & tips with diagrams about vitamin supplements like vitamin C, B6, B9 & B12....
Essential fatty acids - omega 3 and omega 6 are sometimes referred to as Vitamin F. The body is not...

Disclaimer - All information and content on this site are for information and educational purposes only. The information should not be used for either diagnosis or treatment or both for any health related problem or disease. Always seek the advice of a qualified physician for medical diagnosis and treatment. Full Disclaimer

© All Rights Reserved 1997 - 2021

This site uses cookies to deliver our services. By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Use