INTEGRATED EXPRESSION OF GLOMERULAR EXTRACELLULAR-MATRIX PROTEINS ANDBETA-1 INTEGRINS IN MONOCLONAL LIGHT CHAIN-RELATED RENAL DISEASES

Light-chain deposition disease (LCDD) and amyloid light-chain amyloido sis (AL-Am) represent the two classical diseases associated with glome rular alterations in monoclonal light chain-related renal diseases. LC DD is characterized by deposition of extracellular matrix proteins in the mesangium, thus creating the morphologic appearance recognized as nodular glomerulosclerosis, In AL-Am, the mesangial matrix is replaced by polymerized light chains in the form of amyloid fibrils. Integrins are responsible for cell-to-cell and cell-to-matrix communication and , therefore, are expected to play a key role in the alterations encoun tered in these two diseases. The present article addresses the express ion of selected extracellular matrix proteins (collagen IV, laminin, f ibronectin, and tenascin) and their respective receptor beta 1 integri ns (alpha 2, alpha 3, alpha 5, and alpha 9) in glomeruli with LCDD and AL-Am by immunohistochemical methods. The corresponding integrin (alp ha 9 beta 1) co-localized with tenascin in the center of the mesangial nodules in LCDD. In AL-An, tenascin is found primarily at the periphe ry of replaced mesangial areas and in the remaining mesangium not repl aced by the amyloid, Tenascin co-localizes with alpha 9 beta 1 integri n in mesangial areas in the earlier phases of the process, Fibronectin , laminin, and collagen TV, although increased in absolute amounts, ar e pushed toward the periphery of mesangial areas, in which correlated expression of their corresponding beta 1 integrins (alpha 2, alpha 3, and alpha 5, respectively) is documented in both LCDD and AL-Am. Depos ition of tenascin might be at least partially responsible for the perp etuation and irreversibility of the glomerular lesion in LCDD.