Evaluation of anthropometric parameters, white blood cell count, and morphological changes of red blood cells in a pristane-induced rheumatoid arthritis rat model.

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.