Adipokines: Biomarkers for osteoarthritis?

Table 1 Relationship of adipokines with osteoarthritis

Adipokines	Association with BMI	Plasma levels between genders	Plasma levels between groups	Levels in OA patients
Leptin	positive	women > men	OA > control	SF > plasma
Adiponectin	negative	women > men	control > OA	plasma > SF
Visfatin	positive	unclear	OA > control	SF > plasma
Resistin	unclear	women > men	OA > control	plasma > SF

BMI: Body mass index; OA: Osteoarthritis; SF: Synovial fluid.

Table 2 Effects of adipokines on osteoarthritis pathogenesis

Adipokines	Proteases	Cytokines	Inflammation	Cartilage	Bone
Leptin	↑MMP-1 ↑MMP-3 ↑MMP-9 ↑MMP-13 ↑Cysteine proteases ↑ADAMTS-4 ↑ADAMTS-5	↑IL-1β↑IL-6 ↑IL-8 ↓FGF ↑TNF-α↑IGF-1 ↑TGF-β↑GRO ↑MCP-1	↑NOS2 ↑iNOS ↑PGE2 ↑COX-2	↓↑Chondrocyte proliferation ↑Proteoglycan synthesis ↑Collagen synthesis	↑Osteoblast proliferation ↑Ossification ↑ALP ↑OC
Adiponectin	↑MMP-1 ↑MMP-3 ↑MMP-9 ↑↓MMP-13 ↑TIMP-1 ↑TIMP-2	↑IL-6 ↑IL-8 ↑MCP-1 ↑VCAM-1	↑NOS2 ↑PGE2 ↑VEGF	↑Chondrocyte proliferation ↑Proteoglycan synthesis ↑Collagen synthesis ↑Matrix mineralization	↑Osteoblast proliferation ↑Osteoclast differentiation ↑RANKL ↓OPG
Visfatin	↑MMP-3, ↑MMP-13, ↑ADAMTS-4, ↑ADAMTS-5	↑IL-1β↑IL-6 ↑TNF-α	↑NO ↑PGE2	↓Chondrocyte phenotype ↓Proteoglycan synthesis ↓Collagen synthesis	↑Osteoblast proliferation ↓Osteoclast differentiation
Resistin	↑MMP-1 ↑MMP-13 ↑ADAMTS-4	↑IL-6 ↑TNF-α	↑PGE2	↓Proteoglycan synthesis ↓Collagen synthesis	↑Osteoblast proliferation ↑Osteoclast differentiation

ADAMTS: A disintegrin and metalloproteinase with thrombospondin motifs; ALP: Alkaline phosphatase; COX-2: Cyclooxygenasse-2; FGF: Fibroblast growth factor; GRO: Growth-related oncogene; IGF-1: Insulin-like growth factor-1; IL: Interleukin; iNOS: Inducible nitric oxide synthase; MCP-1: Monocyte chemo-attractant protein-1; MMP: Metalloproteinases; NO: Nitric oxide; NOS2: Type 2 nitric oxide synthase; OC: Osteocalcin; OPG: Osteoprotegerin; PGE2: Prostaglandin E2; RANKL: Receptor activator of nuclear factor kappa-B ligand; TGF-β: Transforming growth factor-beta; TIMP: Tissue inhibitor of metalloproteinases; TNF-α: Tumor necrosis factor-alpha; VCAM-1: Vascular cell adhesion molecule-1; VEGF: Vascular endothelial growth factor.