Identification of a central role for complement in osteoarthritis. Academic Article uri icon

Overview

abstract

  • Osteoarthritis, characterized by the breakdown of articular cartilage in synovial joints, has long been viewed as the result of 'wear and tear'. Although low-grade inflammation is detected in osteoarthritis, its role is unclear. Here we identify a central role for the inflammatory complement system in the pathogenesis of osteoarthritis. Through proteomic and transcriptomic analyses of synovial fluids and membranes from individuals with osteoarthritis, we find that expression and activation of complement is abnormally high in human osteoarthritic joints. Using mice genetically deficient in complement component 5 (C5), C6 or the complement regulatory protein CD59a, we show that complement, specifically, the membrane attack complex (MAC)-mediated arm of complement, is crucial to the development of arthritis in three different mouse models of osteoarthritis. Pharmacological modulation of complement in wild-type mice confirmed the results obtained with genetically deficient mice. Expression of inflammatory and degradative molecules was lower in chondrocytes from destabilized joints from C5-deficient mice than C5-sufficient mice, and MAC induced production of these molecules in cultured chondrocytes. Further, MAC colocalized with matrix metalloprotease 13 (MMP13) and with activated extracellular signal-regulated kinase (ERK) around chondrocytes in human osteoarthritic cartilage. Our findings indicate that dysregulation of complement in synovial joints has a key role in the pathogenesis of osteoarthritis.

publication date

  • November 6, 2011

Research

keywords

  • Complement C5
  • Complement Membrane Attack Complex
  • Osteoarthritis

Identity

PubMed Central ID

  • PMC3257059

Scopus Document Identifier

  • 84856100338

Digital Object Identifier (DOI)

  • 10.1038/nm.2543

PubMed ID

  • 22057346

Additional Document Info

volume

  • 17

issue

  • 12