Collagen isotypes, laminin, and fibronectin in granulomas of the liver and intestines of Schistosoma mansoni-infected mice.

Patterns of fibrosis within hepatic and intestinal granulomas of Schistosoma mansoni-infected mice were analyzed by indirect immunofluorescence. Deposition of collagen isotypes, laminin, and fibronectin was evaluated semiquantitatively between 8 and 20 weeks of the infection. Liver granulomas were the largest at 8 weeks and contained low amounts of type I and higher amounts of type III collagen and fibronectin. Collagen deposition became pronounced as infection progressed. The relative amounts of type I collagen deposits rose and equalled that of type III. In the smaller immunomodulated granulomas at 20 weeks both types I and III were high, and type IV collagen deposition was observed. Fibronectin and laminin deposits were also detected. The small ileal granulomas did not change their size during the course of the infection. At 8 weeks, connective tissue matrix deposition was barely detectable within these lesions. Gradually, small deposits of types I and III appeared in equal amounts and attained highest levels by 20 weeks of the infection. Fibronectin deposits at that time were very prominent but laminin and type IV collagen were absent. Colon granulomas at 8 weeks of the infection were only somewhat smaller than those of the liver, yet contained very sparse deposits of types I and III collagen. During the ensuing weeks collagen deposits rose only slightly. By 20 weeks the granulomas diminished in size and within those lesions type III collagen was predominant. Whereas the presence of fibronectin was pronounced, type IV collagen and laminin were detectable only in trace amounts. These observations indicate the existence of important organ-related differences in the intragranulomatous deposition of connective tissue matrix.