IN-SITU HYBRIDIZATION IN THE STUDY OF REMODELING IN PROLIFERATIVE GLOMERULONEPHRITIS

In situ hybridization combined with immunohistochemistry provides a po werful tool to study the temporal and spatial relationships between ce llular sources of mRNA and localization of translated protein in norma l biologic and pathologic processes. In this symposium, techniques in probe selection for the detection of mRNA in normal kidney and renal d isease were discussed. Examples of the application of in situ hybridiz ation in the study of renal disease were demonstrated using a model of proliferative glomerulonephritis induced by habu snake venom. This mo del follows an accelerated course of remodeling involving mesangial ce ll migration, proliferation, and extracellular matrix synthesis. The c ellular sources and temporal expression of 2 adhesive proteins, fibron ectin and thrombospondin, known to have a role in cell remodeling duri ng embryogenesis and wound healing, were examined and compared to mesa ngial cell behaviors during the course of habu venom-induced glomerulo nephritis. Mesangial cell migration in early lesions was associated wi th thrombospondin and fibronectin derived from platelets or macrophage s. Thrombospondin mRNA and protein peaked at 48 hr after habu venom an d were associated with mesangial cell proliferation; but thrombospondi n mRNA and protein declined at 72 hr when expression of collagen type TV and laminin mRNA and protein peaked. Mesangial cell expression of f ibronectin first appeared at 48 hr, and peaked at 72 hr after habu ven om. Thus, mesangial cell migration was associated with exogenous fibro nectin and thrombospondin derived from platelets or macrophages. Mesan gial cell expression of thrombospondin was associated with migration a nd proliferation, whereas, expression of fibronectin was associated wi th proliferation and matrix synthesis. These results suggest distincti ve temporal and spatial roles for thrombospondin and fibronectin in re modeling during glomerulonephritis and illustrate the utility of in si tu hybridization and immunohistochemistry in the detection of cellular sources of translated proteins.