The precise cause of autoimmune diseases such as rheumatoid arthritis remains uncertain. Collagen
induced arthritis (CIA) in animals is the most commonly used model of human rheumatoid arthritis
(RA). Exposure of humans and animals to toxic metals is widespread. Cadmium is one of the most
prevalent nephrotoxic heavy metal, but it may cause other systemic toxicity as well. Cadmium may cause
adverse health effects by impairment of the immune systems and induction of reactive oxygen species.
Since rheumatoid arthritis pathogenesis involve immune system disorder and chronic inflammation,
the present study has been designed to find out the effect of cadmium chloride exposure on clinical
manifestation of development of collagen induced rheumatoid arthritis. Arthritis was induced in rats
by intradermal injection of emulsion of type II collagen in Complete Freund’s Adjuvant. Rats were treated
with cadmium chloride dissolved in drinking water at concentrations of 5 ppm and 50 ppm for 21 days
from day of immunization. The effects of cadmium in the rats were assessed by biochemical parameters
(articular elastase, articular nitrite, lipid peroxidation, reduced glutathione, catalase and superoxide
dismutase) histopathological analysis and immunohistochemical expression of pro-inflammatory
cytokines in rat joint tissue. Histopathological changes further confirmed the biochemical and
immunohistochemical results. Our results suggest that exposure to cadmium chloride during the
induction phase of collagen induced arthritis abrogate disease development at lower dose whereas
exacerbates at higher dose in Wistar rats.