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Biophysics - Nephrology - Physics - Rheumatology

Characterization of the Response of Primary Cells Relevant to Dialysis-Related Amyloidosis to ß2-Microglobulin Monomer and Fibrils
Published: Wednesday, November 09, 2011
Author: Morwenna Y. Porter et al.

by Morwenna Y. Porter, Katy E. Routledge, Sheena E. Radford, Eric W. Hewitt

The formation of insoluble amyloid fibrils is associated with an array of devastating human diseases. Dialysis-related amyloidosis (DRA) is a severe complication of hemodialysis that results in the progressive destruction of the bones and joints. Elevated concentrations of ß2-microglobulin (ß2m) in the serum of subjects on hemodialysis promote the formation of amyloid fibrils in the osteoarticular tissues, but the cellular basis for the destruction of these tissues in DRA is poorly understood. In this study we performed a systematic analysis of the interaction of monomeric and fibrillar ß2m with primary human cells of the types present in the synovial joints of subjects with DRA. Building upon observations that macrophages infiltrate ß2m amyloid deposits in vivo we demonstrate that monocytes, the precursors of macrophages, cannot degrade ß2m fibrils, and that both monomeric ß2m and fibrillar ß2m are cytotoxic to these cells. ß2m fibrils also impair the formation of bone resorbing osteoclasts from monocytes and reduce the viability of osteoblasts, the cell type that produces bone. As a consequence, we predict that ß2m amyloid will disrupt the remodelling of the bone, which is critical for the maintenance of this tissue. Moreover, we show that ß2m fibrils reduce the viability of chondrocytes, rationalizing the loss of cartilage in DRA. Together, our observations demonstrate that ß2m cytotoxicity has multiple cellular targets in the osteoarticular tissues and is likely to be a key factor in the bone and joint destruction characteristic of DRA.