Gut bacterial consortium is essential for the homeostasis of the immune system in mammals. A significant role in maintaining this balance play short-chain fatty acids (SCFA), bacterial metabolites resulting from fermentation of dietary oligosaccharides. The most significant are butyric, propionic and acetic acids present in the microbiome in a specified mole ratio, but these proportions may change due to diet, age, diseases, and other factors. SCFA are the type of messengers between microbiota and immune system. They are responsible for maintaining the balance in the pro- and anti-inflammatory reaction through the set of free fatty acid receptors (GPR). Short chain fatty acids may induce regulatory T-cells (Treg) by an bakteinhibition of histone deacetylase enzyme; the biggest inhibitory potential has butyric acid, causing proliferation and an increase of the functional capabilities of Treg cells. Manipulation of the gut microbiome composition and SCFA level constitutes a promising tool supporting treatment of chronic gastrointestinal diseases associated with an inflammation or caused by dysbiosis due to intensive use of antibiotics.

We investigated the association between dietary intake of n-3 and n-6 polyunsaturated fatty acids (PUFAs), serum profiles, and immune and inflammatory markers in juvenile idiopathic arthritis (JIA) in relation to onset, activity, and duration. A total of 66 JIA patients and 42 controls were included. Serum PUFA levels were assessed by gas-liquid chromatography-mass spectrometry, a dietary intake by 7-day dietary record method, and IL-6, IL-10, and IL-17A levels using ELISA. Dietary PUFA intake did not differ between the JIA group and controls. Intakes of n-6 and n-3 PUFA and serum levels were not associated. Levels of total n-6 PUFA and linoleic acid (LA) were higher in inactive JIA than in active JIA. Patients with active and short-lasting disease (less than 3 months from diagnosis) had significantly lower levels of arachidonic acid (AA) and docosahexaenoic acid (DHA) than the control. Serum α-linolenic acid (ALA) levels were significantly higher in poly-JIA than in oligo-JIA and in controls. We found significantly higher serum IL-10 levels in JIA than in controls. Serum n-6 and n-3 levels were significantly negatively correlated with active joint count, erythrocyte sedimentation rate, and C-reactive protein and positively with platelet count. Our study presents the low levels of AA and DHA in the active phase of short-lasting JIA, particularly poly-JIA, and the relationship between n-6 and n-3 PUFA and classic markers of inflammation. PUFAs may contribute to the pathogenesis of JIA and support a necessity to identify new targets suitable for successful interventional studies in JIA patients.

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