According to the researchers, a Western diet appears to be sufficient to cause microbial imbalance and enhance sensitivity to IL-23-mediated psoriasis-like skin inflammation.
According to a study headed by UC Davis Health experts, a high-sugar, high-fat diet causes an imbalance in the gut’s microbiome, which can lead to inflammatory skin disorders like psoriasis.
The study, published in the Journal of Investigative Dermatology, explains how switching to a more balanced diet improves gut health and reduces skin inflammation.
“Earlier studies have shown that Western diet, characterized by its high sugar and fat content, can lead to significant skin inflammation and psoriasis flares,” said Sam T. Hwang, professor and chair of dermatology at UC Davis Health and senior author on the study. “Despite having powerful anti-inflammatory drugs for the skin condition, our study indicates that simple changes in diet may also have significant effects on psoriasis.”
Psoriasis is a chronic skin disease that is connected to the immune system. When immune cells assault healthy skin cells inadvertently, the result is skin inflammation, scale development, and painful red areas. Psoriatic arthritis affects up to 30% of psoriasis victims, causing symptoms such as morning stiffness and tiredness, swollen fingers and toes, joint discomfort, and nail abnormalities.
The microbial balance in the intestines and skin inflammation are both affected by diet. The gut microbiota, or the population of bacteria that live in the intestines, is regulated by food, which is one of the most controllable variables. The microbial population and functions of the gut can alter quickly when you eat a Western diet. Dysbiosis, or a change in microbial equilibrium, contributes to gut inflammation.
The researchers sought to see if intestinal dysbiosis impacts skin and joint inflammation since bacteria in the stomach may play a major role in determining inflammation. They investigated the effects of food on psoriasis and psoriatic arthritis using a mouse model. Interleukin-23 (IL-23) minicircle DNA was delivered into mice to produce a reaction that mimicked psoriasis-like skin and joint disorders.
Many inflammatory autoimmune responses, such as psoriasis and inflammatory bowel disease, are caused by the protein IL-23, which is produced by immune cells. A short-term Western diet appears to be sufficient to create microbial imbalance and increase vulnerability to IL-23-mediated psoriasis-like skin inflammation, according to Hwang and his colleagues.
“There is a clear link between skin inflammation and changes in the gut microbiome due to food intake,” Hwang said. “The bacterial balance in the gut disrupted shortly after starting a Western diet, and worsened psoriatic skin and joint inflammation.”
One of the researchers most important findings was the identification of the gut microbiota as a pathogenic connection between food and psoriatic inflammatory symptoms. Antibiotics also reduce skin and joint inflammation by blocking the effects of the Western diet, according to the study.
Despite the presence of IL-23 inflammatory proteins, the researchers sought to see if moving to a balanced diet might help restore balance in the gut microbiome. They gave mice a Western diet for six weeks before generating psoriasis and psoriatic arthritis symptoms with an IL-23-producing chemical. The mice were then randomly separated into two groups: one that ate a Western diet for another four weeks, and another that ate a balanced diet for the same amount of time.
Their research found that mice that ate a high-sugar, high-fat diet for 10 weeks were prone to skin and joint inflammation. Mice that were shifted to a balanced diet had less skin scaling and reduced ear thickness than mice who were on a Western diet. The reduction in skin inflammation in mice who were taken off the Western diet suggests that the Western diet has a short-term effect on skin inflammation.
This implies that dietary modifications might partially restore the proinflammatory effects of the Western diet as well as the altering of gut bacteria.
“It was quite surprising that a simple diet modification of less sugar and fat may have significant effects on psoriasis,” said Zhenrui Shi, visiting assistant researcher in the UC Davis Department of Dermatology and lead author on the study. “These findings reveal that patients with psoriatic skin and joint disease should consider changing to a healthier dietary pattern.”
“This work reflects a successful collaboration among researchers, especially with Professor Satya Dandekar and her team at the Department of Medical Microbiology and Immunology and Professor Yu-Jui Yvonne Wan at the Department of Medical Pathology and Laboratory Medicine,” Hwang said.