Figure 3

(A) Identification of an exercise-induced gene network involved in tissue fibrosis using the Ingenuity Pathways Analysis knowledge database. Several genes regulated by TGF-β were negatively modulated, and a negative modulator of TGF-β (LTBP1) was induced by exercise in a manner consistent with the reduction in tissue fibrosis and improved performance in myositis patients (see text for further information). (B) Model of exercise-induced reduction in fibrosis in autoimmune myositis patients. Collagen synthesis is suppressed because of a reduction in growth factor production and an increase in inhibitory molecules such as LTBP1. The reduction in collagen processing likely contributes to the decrease in ECM deposition. This, together with an increase in ECM degradation by collagen-cleaving enzymes and matrix metalloproteases, will result in a reduction in tissue fibrosis. (Panel A image: © 2000–2010 Ingenuity Systems, Inc. All rights reserved.)