Description

Axial spondyloarthritis (AxSpA) is the second most common chronic inflammatory rheumatic disease, which develops preferentially in young subjects and results in a significant impairment of quality of life, particularly due to painful symptoms. The importance of the digestive system has long been recognized, since this disease is considered to be part of a larger group of diseases including Crohn's disease and ulcerative colitis because of their frequent association in the same patient, and because leaky gut disorders and alterations of the intestinal microbiota (dysbiosis) have been described in these patients. These abnormalities may stimulate the immune system and therefore be involved in inflammatory processes (especially Th17). The available treatments are based on non-steroidal anti-inflammatory drugs, and in the event of failure or intolerance, biomedicines targeting TNF can be used. Therapeutic monoclonal antibodies against IL-17 have recently enriched the therapeutic arsenal. Although most anti-TNF agents have a beneficial effect on the rheumatologic and digestive aspects of these diseases, anti-IL-17 agents are not expected to be effective in inflammatory bowel diseases.

Indeed, a deleterious role of anti-IL-17 on the intestinal microbiota has even been demonstrated, which could result in a reduction of the systemic anti-inflammatory effect expected from these molecules, and consequently of the clinical benefit felt by the patient. In fact, anti-IL-17s lead to a significant decrease in Clostridiales, bacteria that participate in intestinal homeostasis.

Fiber is the main source of energy for colonic bacteria and its consumption favorably modifies the composition of the microbiota in just a few days. Their fermentation in the colon releases short-chain fatty acids (SCFAs). Clostridiales contain many strains producing SCFAs. These SCFAs can restore the intestinal barrier and promote certain anti-inflammatory cells, including regulatory T cells (Tregs), which are essential to the mechanisms in tolerance of the self. Fibers could therefore correct the intestinal abnormalities present in AxSpA patients and aggravated by anti-IL-17 drugs and thus improve the therapeutic response to these treatments.

The hypothesis is therefore that dietary fiber will correct the dysbiosis in AxSpA patients and increase the release of SCFAs, which favorably modulate the immune response and thus improve AxSpA.