Duodenal mucosal ferritin in rheumatoid arthritis: implications for anaemia of chronic disease

Anaemia is a common feature of rheumatoid arthritis (RA) and other chronic diseases. Among the alterations in iron metabolism contributing to this effect is a decrease in intestinal iron absorption. The mechanism for this is unknown, but might involve a 'mucosal block' process similar to that proposed in iron overload, whereby increased expression of an enterocyte storage protein binds absorbed iron and prevents its transfer to the circulation. We examined the effect of disease-modifying therapy on ferritin expression in duodenal mucosa in RA to determine whether it may play a role in the 'mucosal block' process. Endoscopic small bowel biopsies were obtained from 11 patients with active RA both before, and 6 months after, a course of either gold or methotrexate (MTX). Mucosal ferritin levels in small bowel and stomach were measured by radio-immune assay. Duodenal mucosal ferritin decreased significantly following treatment (p <0.05). There were no changes in gastric mucosal ferritin. The fall in duodenal mucosal ferritin correlated with indices of disease activity at start of therapy, and the largest decreases were in those patients showing the best response to treatment in terms of a fall in inflammatory markers. Site-specific changes in mucosal ferritin may underlie the altered iron absorption observed in active inflammatory disease by modifying the enterocyte 'mucosal block'.