Geometric Morphometrics Reveals That Alfacalcidol, but Not Cholecalciferol, Preserves Renal Corpuscle Architecture in Rheumatoid Arthritis in Rats

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 (<i>n</i> = 10) received saline i.c., the PIA group (<i>n</i> = 10) was administered pristane i.c., PIA-ALF group (<i>n</i> = 10) was administered pristane i.c. and alfacalcidol orally, and the PIA-CH group (<i>n</i> = 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 (<i>p</i> < 0.0001) and PIA-CH (<i>p</i> = 0.0065) groups. In contrast, no statistically significant differences were observed in the PIA-ALF group (<i>p</i> = 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.