An Update on the Role of Leptin in the Immuno-Metabolism of Cartilage

Abstract

Since its discovery in 1994, leptin has been considered as an adipokine with pleiotropic effects. In this review, we summarize the actual information about the impact of this hormone on cartilage metabolism and pathology. Leptin signalling depends on the interaction with leptin receptor LEPR, being the long isoform of the receptor (LEPRb) the one with more efficient intracellular signalling. Chondrocytes express the long isoform of the leptin receptor and in these cells, leptin signalling, alone or in combination with other molecules, induces the expression of pro-inflammatory molecules and cartilage degenerative enzymes. Leptin has been shown to increase the proliferation and activation of immune cells, increasing the severity of immune degenerative cartilage diseases. Leptin expression in serum and synovial fluid are related to degenerative diseases such as osteoarthritis (OA), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Inhibition of leptin signalling showed to have protective effects in these diseases showing the key role of leptin in cartilage degeneration.

The Effect of Platelet-Rich Plasma on the Intra-Articular Microenvironment in Knee Osteoarthritis

“…The IFP and the adipocytes within it may participate in the pathophysiology of knee OA by releasing various proinflammatory adipokines that can contribute to dedifferentiation and inflammation in chondrocytes [ 34 , 35 , 36 ]. Moreover, adiponectin and leptin can further promote cartilage degradation by inducing the infiltration of leukocytes and monocytes in OA cartilage [ 37 , 38 , 39 ]. This study showed that the combination of PRP and hyaluronic acid (HA) decreased the inflammatory potential of IFP adipocytes through the down-regulation of proinflammatory cytokines and adipokines.…”

Leptin Protein Expression and Promoter Methylation in Ovarian Cancer: A Strong Prognostic Value with Theranostic Promises

“…Ovarian cancer is a disease marked by the absence of early specific signs and silent clinical symptoms making its diagnosis at an early stage challenging, thus leading to higher mortality rates, being the highest deadly cancer among all gynecological tumors [ 5 , 41 , 42 , 43 ]. In this context, lipid metabolism and obesity were reported as the main risk factors for several chronic diseases such as chronic inflammation, cardiovascular diseases, diabetes, bone degenerative diseases and cancer, which has urged scientists to investigate the underlying biological and molecular links [ 38 , 39 , 44 , 45 , 46 , 47 , 48 ]. Furthermore, several studies have linked leptin expression with several upstream (pathways inducing LEP expression) and/or downstream (pathways induced by LEP) inflammatory-like pathways that are involved in obesity-associated diseases mentioned above, mainly cancer [ 48 , 49 ].…”

Leptin in Osteoarthritis and Rheumatoid Arthritis: Player or Bystander?

“…Leptin was reported to be a key regulator in cartilage metabolism [ 59 ] ( Figure 1 ). Progressive articular cartilage destruction is a main characteristic of OA.…”