Introduction : Rheumatoid arthritis (RA) is an autoimmune disease characterized by a complex pathophysiological mechanism. The adipose tissue, blood and its cellular components are less-studied extra-articular manifestations of RA. Aim : In this study, we used a pristane-induced RA rat model to assess the impact of RA-induced inflammation on anthropometric parameters, obesity indices, white blood cell differentiation, and morphological changes in red blood cells. Materials and methods : The randomized controlled, prospective, experimental study involved 20 adult female Wistar rats, aged 12-13 weeks, with body weights ranging from 180 to 220 grams. The rats were randomly assigned to two groups: an experimental RA-induced group (PIA group; n=10) and a control group of healthy animals (n=10). Rheumatoid arthritis was induced by intradermal injection of 150 μL of pristane at the dorsal base of the tail. Results : Rats in the PIA group exhibited significantly lower values of body weight ( p =0.002), abdominal circumference ( p =0.011), and BMI ( p =0.028) compared to those in the control group. The number of neutrophils ( p <0.001) and eosinophils ( p <0.001) in the PIA group was significantly higher than in the control group, while the number of lymphocytes ( p =0.001) was lower. Peripheral blood smear analysis showed a significant increase in the number of dacryocytes ( p =0.003), anulocytes ( p =0.002), spherocytes ( p <0.001), and reticulocytes ( p <0.001) in the PIA group compared to the control group. Conclusion : This study demonstrates that the pathological processes in rheumatoid arthritis are reflected in the anthropometric parameters, the distribution of specific leukocyte types, and the morphological characteristics of erythrocytes. These factors collectively contribute to the complexity of disease progression in RA.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by inflammation and destruction of cartilage, as well as by extra-articular manifestations. Rheumatoid nephropathy is a common complication of RA and its principal target is the renal corpuscle. Vitamin D and its analogs exert immunomodulatory actions throughout the body due to the widespread of their receptors. Our study aimed to compare the effects of cholecalciferol (vitamin D3) and alfacalcidol on renal corpuscle changes in pristane-induced RA model following a 28-day treatment, using geometric morphometrics. Forty female Wistar rats (190–210 g; 12–13 weeks old) were randomly assigned to four groups: the control (Cont) group (n = 10) received saline i.c., the PIA group (n = 10) was administered pristane i.c., PIA-ALF group (n = 10) was administered pristane i.c. and alfacalcidol orally, and the PIA-CH group (n = 10) was injected i.c. with pristane and received cholecalciferol orally. Pristane administration was used for RA induction. At the end of the experiment, the left kidneys were removed and processed by standard histological procedures for geometric morphometric analysis. Geometric morphometric analysis demonstrated that, compared with the control group, the architecture of the renal corpuscles was altered in the PIA (p < 0.0001) and PIA-CH (p = 0.0065) groups. In contrast, no statistically significant differences were observed in the PIA-ALF group (p = 0.3011). Geometric morphometric analysis demonstrated that alfacalcidol, but not cholecalciferol, exertedaprotective effect on the renal corpuscle architecture in pristane-induced rheumatoid arthritis in rats.