Environmental factors are suspected of triggering rheumatoid arthritis (RA). One such factor is oxidative stress (OS), which is a step in ecotoxin detoxification and a damaging factor. The linkage of ecotoxin-triggered OS with clinical and laboratory RA indices in patients and individuals at the pre-RA stage was studied in patients with early (e) (n = 35) and advanced (a) stages of RA (n = 25) and individuals at pre-RA stages (FDR-First-Degree Relative(s), pre-RA, n = 72) in comparison with 52 healthy individuals without autoimmune and immunoinflammatory diseases in their family history (Controls). Ecotoxins within permissible concentration limits were associated with serum levels of OS markers in all cohorts, including Controls. Serum oxidized low-density lipoprotein (oxLDL) levels in pre-RA and eRA cohorts exceeded Control values. Significant differences were found in anti-oxLDL antibody correlations and OS markers. In pre-RA and both RA cohorts, a relationship was found with regards to serum antibodies to cyclic citrullinated peptide (ACCP) levels. Thus, ecotoxin-induced OS likely triggers pathogenic mechanisms at the pre-RA stage and RA onset.

Introduction: Heavy metals can cause disturbances in the functioning of various systems of the human body and play an important role in the development of autoimmune diseases. Objective: To assess the relationship between heavy metals and metalloids in soil and the level of rheumatoid factor (RF) in adult patients with rheumatoid arthritis living in the Republic of Tatarstan. Materials and methods: The study included 380 permanent residents of the Republic of Tatarstan diagnosed with rheumatoid arthritis. Soil samples were collected in residential areas of the cases and tested for heavy metal concentrations. Odds ratios were used to establish the relationship between soil concentrations of heavy metals and the levels of rheumatoid factor in the blood of subjects. Results: Changes in soil levels of heavy metals were found to correlate with those in the levels of rheumatoid factor in the blood of adults with rheumatoid arthritis. Patients with an advanced stage of the disease living in the areas with soil levels of cadmium above 0.7 mg/kg and nickel above 50 mg/kg and having an elevated level of RF were 1.8 (OR = 1.7 CI [1.00: 2.88]) and 2 times more frequent (OR = 2.17 CI [1.06: 4.45]), respectively. Conclusions: Increased levels of heavy metals in soil provoke changes in immunological parameters in patients with various stages of rheumatoid arthritis. In areas with the elevated geochemical background concentrations of cadmium and nickel, higher levels of rheumatoid factor are observed in patients with advanced rheumatoid arthritis.

In this study, in most cases in soils susceptible to the accumulation of heavy metals, the highest content of heavy metals was observed in the surface layers of the soil profile. We calculated the values of three pollution indices based on the determination of individual heavy metals (Al, As, Cd, Pb, Sr) and pollutants (Cu, Co, Cr, Zn, Mn, Fe, Mo, Ni) in the territory of the Republic of Tatarstan. The overall degree of pollution and environmental risk assessment were carried out using complex indices NPI and RI. The possibility of accumulation of individual elements in soil horizons was determined using the iogeochemical index BGI. The content of heavy metals in the soils of the Republic of Tatarstan, such as As, Pb, Co, Cu, Fe in the soil horizons was several times higher than the natural content of these metals, which is confirmed by three calculated indicators, taking into account that the values obtained for the O horizon using NPI indices and RI are consistent with each other, and BGI is consistent for individual elements (As, Pb, Co, Cu, Fe, Cd, Cr, Mn and Mo).