transforming-growth-factor-beta and Chondrocalcinosis

Recent advances have stimulated new interest in the area of crystal arthritis, as microcrystals can be considered to be endogenous "danger signals" and are potent stimulators of immune as well as non-immune cells. The best known microcrystals include urate (MSU), and calcium pyrophosphate (CPP) crystals, associated with gout and pseudogout, respectively. Acute inflammation is the hallmark of the acute tissue reaction to crystals in both gout and pseudogout. The mechanisms leading to joint inflammation in these diseases involve first crystal formation and subsequent coating with serum proteins. Crystals can then interact with plasma cell membrane, either directly or via membrane receptors, leading to NLRP3 activation, proteolytic cleavage and maturation of pro-interleukin-1β (pro-IL1β) and secretion of mature IL1β. Once released, this cytokine orchestrates a series of events leading to endothelial cell activation and neutrophil recruitment. Ultimately, gout resolution involves several mechanisms including monocyte differentiation into macrophage, clearance of apoptotic neutrophils by macrophages, production of Transforming Growth Factor (TGF-β) and modification of protein coating on the crystal surface. This review will examine these different steps.

Topics: Apoptosis; Arthritis, Gouty; Biomarkers; Calcium Phosphates; Carrier Proteins; Chondrocalcinosis; Endothelial Cells; Gout; Humans; Inflammasomes; Inflammation; Interleukin-1beta; Macrophages; Neutrophils; NLR Family, Pyrin Domain-Containing 3 Protein; Proteolysis; Transforming Growth Factor beta; Uric Acid

Topics: Calcium Pyrophosphate; Chondrocalcinosis; Crystallization; Humans; Osteoarthritis; Synovial Fluid; Transforming Growth Factor beta

Articular cartilage affected by calcium pyrophosphate dihydrate (CPPD) crystal deposition contains abnormal chondrocytes with morphologic similarities to the terminally differentiated hypertrophic chondrocytes that mineralize in growth plate cartilage. These chondrocytes also elaborate high levels of extracellular inorganic pyrophosphate (PPi), an essential component of the CPPD crystal. Several factors that stimulate articular chondrocyte PPi elaboration also induce terminal differentiation in growth plate chondrocytes. We hypothesized that factors such as thyroid hormones (T3 and T4) that are potent stimulants of growth plate chondrocyte hypertrophy might also stimulate articular chondrocyte hypertrophic differentiation. We also hypothesized that like transforming growth factor-beta (TGF-beta), ascorbate, and retinoic acid, thyroid hormones would increase chondrocyte PPi elaboration.. We determined the effects of T3, T4, and TGF-beta on markers of the hypertrophic phenotype such as alkaline phosphatase (ALPase) activity and type X collagen production; and the effects of T3 and T4 on processes implicated in CPPD crystal formation including PPi elaboration and nucleoside triphosphate pyrophosphohydrolase (NTPPPH) activity in adult porcine articular chondrocytes in culture.. ALPase activity increased 3-fold with T3 and T4 and 1.3-fold with TGF-beta. Type X collagen levels also increased with thyroid hormone treatment. [125I]T3 binding studies proved the existence of saturable T3 receptors on chondrocytes. Media [PPi] and cellular NTPPPH activity significantly increased in cultures treated with 1-10 nM T3 or 100-500 nM T4.. Increased PPi elaboration is an additional and previously unrecognized feature of hypertrophic differentiation in articular chondrocytes. These terminally differentiated chondrocytes may play a pathogenic role in CPPD crystal deposition disease.

Topics: Alkaline Phosphatase; Animals; Binding Sites; Calcium Pyrophosphate; Cell Differentiation; Cell Size; Cells, Cultured; Chondrocalcinosis; Chondrocytes; Collagen; Diphosphates; Phenotype; Pyrophosphatases; Swine; Thymidine; Thyroxine; Transforming Growth Factor beta; Triiodothyronine; Tritium

The elaboration of excess extracellular inorganic pyrophosphate (ePPi) by cartilage contributes to calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. Transforming growth factor-beta 1 (TGF beta 1) is the only defined physiologic stimulant of cartilage ePPi elaboration. The mechanism of ePPi generation by chondrocytes is unknown, but current evidence suggests that TGF beta 1 induced ePPi is made intracellularly. An active transport mechanism such as an anion transporter would then be necessary to export ePPi to the matrix where crystals form. We determined the effect of probenecid (PB), an anion transport inhibitor, on TGF beta 1 induced ePPi elaboration.. Porcine hyaline articular chondrocytes in high density monolayer cultures were exposed to serum-free media with and without TGF beta 1 and/or PB. ePPi was measured in the media after 48-96 h of exposure. Cell injury was measured by examining the release of 3H-deoxyglucose from chondrocytes. The activity of the ePPi generating ectoenzyme nucleoside triphosphate pyrophosphohydrolase (NTPPPH) and media lactate concentrations were measured with standard colorimetric assays. As PB may inhibit phosphodiesterase (PDE), its effects on ePPi generation were compared with isobutylmethylxanthine (IBMX), a specific PDE inhibitor.. PB inhibited TGF beta 1 induced ePPi elaboration by chondrocytes. PB did not cause membrane injury or decrease NTPPPH activity. Lactate production was decreased by PB but did not correlate with the effects of PB on ePPi elaboration. IBMX did not inhibit TGF beta 1 effect on ePPi elaboration.. PB blocks TGF beta 1 induced ePPi elaboration. This effect is independent of cell membrane injury, decreased NTPPPH activity, or PDE inhibition. Our data implicate a role for anion transport in TGF beta 1 induced ePPi elaboration, and suggest a potential therapy for CPPD disease.

Topics: 1-Methyl-3-isobutylxanthine; Animals; Cartilage, Articular; Chondrocalcinosis; Diphosphates; Knee Joint; Lactates; Lactic Acid; Probenecid; Pyrophosphatases; Swine; Transforming Growth Factor beta

The purpose of this study was to determine the effect of transforming growth factor beta 1 (TGF beta 1) on inorganic pyrophosphate (PPi) elaboration from articular tissues to better understand the pathophysiology of calcium pyrophosphate dihydrate (CPPD) crystal deposition in the joint.. PPi was measured in the media of adult porcine articular tissue in organ culture and monolayer cultures.. TGF beta 1 strongly stimulated PPi elaboration by porcine fibrocartilage and hyaline cartilage. It modestly increased PPi elaboration by ligament, and had no effect on PPi elaborated by synovium. Of all cell types tested in cell culture, only chondrocytes responded to TGF beta 1 by significantly increasing PPi elaboration.. TGF beta 1 stimulates PPi elaboration from hyaline cartilage, fibrocartilage, and ligament, indicating that there is in situ CPPD crystal formation in these tissues. The ability of tissues to respond to TGF beta 1 by increasing PPi elaboration correlates with the prevalence of CPPD crystal deposition found clinically. The unique response of chondrocyte monolayers to TGF beta 1 reinforces the key role of the chondrocyte in PPi elaboration in the joint. These findings support an etiologic role for responsiveness to TGF beta 1 in CPPD disease.

Topics: Animals; Calcium Pyrophosphate; Cartilage; Cartilage, Articular; Cells, Cultured; Chondrocalcinosis; Hyalin; Ligaments; Swine; Synovial Membrane; Tendons; Transforming Growth Factor beta