Inflammatory changes in gingival collagen in the alloxan-diabetic rat.

Abstract

Chronic inflammation was induced by repeatedly injecting ferritin‐antiferritin (AgAb) complex into gingiva of normal, untreated and insulin‐treated alloxan diabetic rats. Blood glucose levels, the urinary excretion of hydroxyproline, and the salt‐soluble, acid‐soluble and insoluble collagen levels in gingiva were measured in all groups of rats. Additionally, the gingival tissues were examined by light and electron microscopy. Injection of AgAb into the gingiva of normal rats produced typical chronic inflammatory cell infiltrates, fibroblasts containing profiles of intracellular collagen, disruption of extracellular collagen fibrils and a reduction in collagen concentration primarily affecting the insoluble fraction. The inflamed gingiva of the diabetic rats demonstrated similar changes histologically except that the macrophages were more congested with phagocytosed material and the fibroblasts appeared smaller and less well developed. Unlike the normal rats, the collagen content of the diabetic gingiva was not reduced by inflammation. This loss of the inflammatory effect on gingival collagen content during experimental diabetes was explained by three possibilities: (1) that diabetic fibroblasts had a decreased ability to effect collagen remodeling during inflammation, (11) that the inflammatory cells responsible for gingival collagen loss were less active in diabetes, and (111) that diabetic gingival collagen, because it was more highly crosslinked than normal, resisted the degradative enzymes produced in increased amounts during the inflammatory process.