Animal models of fibrosis.

This review of the animal models for scleroderma described in the literature demonstrates that there are available a number of induced and spontaneous systems in which to study various aspects of this complex disorder. Each model has its strengths in mimicking certain aspects of the disease--inflammatory, immunologic, or fibrotic--as well as important differences or unstudied aspects, as emphasized in the foregoing discussion. It is apparent that each of these models can contribute to our knowledge of the mechanisms underlying this presently incurable disorder. The most extensively studied model from the histologic, immunologic and biochemical viewpoint is the TSK/+ mutant mouse. Its principal deficiencies are the absence of inflammatory, immunologic, vascular, gastrointestinal, and articular involvement. Our new findings reported in this review demonstrate that certain previously undefined immunologic alterations commonly observed in autoimmune diseases are present in this mutant mouse. Table 3 summarizes the available data on the two most studied models, the TSK/+ mouse and the UCD-L200 chicken, and compares them with SSc. It can be readily seen that there is the need for further studies of many aspects of these models and of the human disease to extend our present knowledge and hopefully achieve a better understanding of the underlying causes and pathologic mechanisms. The existence of genetic mutant animals holds the promise of applying the techniques of molecular biology to address these questions.