Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammation and progressive damage of the joints. A number of genetic and environmental factors have been described as responsible for this disease, whose aetiology still remains not fully understood. Recent investigations have brought to light a role for oral and gut microbiota, capable of regulating immune system, in the pathogenesis of the RA. To better understand the gut-joint link it is important to consider that several environmental factors such as diet and smoking can influence both the microbiota diversity/composition and the arthritis onset/outcome. In particular, the Mediterranean diet is considered a healthy eating pattern, associated with reduced risk for psoriasis and cardiovascular diseases. Smoking can cause several immune dysregulation and represents a risk factor for arthritis onset; in addition smoking can also affect arthritis outcome, by interfering with therapeutic response to synthetic and biological drugs. Smoking influences both oral and gut microflora that can be partially reverted after smoking cessation. Aim of this study is to analyse the impact of a mediterranean diet regimen and smoking habit on the variety and composition of the gut microbiota in RA patients. Correlations between the gut microbiota composition and validated immunological and clinical parameters of disease activity will also be evaluated aiming at identify possible association with drug effectiveness. A better knowledge of the alterations occurring in the gut microbiota of RA patients may enable to set up supportive and individualized strategies.
Mounting evidence suggests a role for gut microbiota in the pathogenesis of RA, since its composition has been observed to differ, with some microbes enriched while other decreased, between diseased and healthy individuals. It is nowadays recognized that, other than therapies, a wide range of environmental factors, mainly diet and smoking, can influence both the microbiota composition and the arthritis outcome. The relevance of diet is suggested by the differences in the gut microbiota between geographically and life style distant populations, moreover the Mediterranean diet is considered a healthy eating pattern, associated with reduced risk for different chronic conditions such as psoriasis and cardiovascular diseases. It is already generally accepted that the smoking habit can cause several immune dysregulation and represents a risk factor for arthritis onset and outcome, by interfering with therapeutic response to synthetic and biological drugs; moreover smoking cessation can partially revert oral and gut microflora abnormalities in healthy individuals. However, data addressing the question of how smoking and Mediterranean diet can influence gut dysbiosis and affect the activity and outcome of RA, are still scarce and non-exhaustive.
In this cross-sectional study the impact of a mediterranean diet regimen and smoking habit on the variety and composition of the gut microbiota in RA patients will be evaluated. Correlations between the gut microbiota composition and validated immunological and clinical parameters of disease activity and severity will also be analysed aiming at identify possible association with drug effectiveness. A better knowledge of the alterations occurring in the gut microbiota of RA patients may enable to set up supportive and individualized strategies.