Release of oxygen radicals by articular chondrocytes: A study of luminol-dependent chemiluminescence and hydrogen peroxide secretion

Abstract

We previously established that normal articular chondrocytes, like macrophages, express class II major histocompatibility antigens, present antigen, and induce mixed and autologous lymphocyte stimulation. In a recent study using the trapped indicator 2',7'-dichlorofluorescein diacetate, we were able to measure levels of intracellular hydrogen peroxide within normal articular chondrocytes (J Immunol 245:690-696, 1990). In the present study, we utilized the technique of chemiluminescence and the biochemical method of quantitating hydrogen peroxide release to measure the production of reactive oxygen intermediates by articular chondrocytes. Chondrocytes, in suspension or adherent to coverslips, showed luminol-dependent chemiluminescence that was dependent on the number and viability of cells. There was a dose-dependent increase in chemiluminescence in response to soluble stimuli, such as phorbol myristate acetate (PMA), concanavalin A (ConA), and f-Met-Leu-Phe (FMLP). Azide inhibited chemiluminescence, suggesting that the light emission in chondrocytes is myeloperoxidase dependent. The antioxidant, catalase, inhibited chemiluminescence but superoxide dismutase had no effect, suggesting that luminol-dependent chemiluminescence in chondrocytes mostly measured hydrogen peroxide. Chemiluminescence was also observed in fragments of live cartilage tissue, indicating that chondrocytes that are cartilage matrix bound can generate the respiratory burst response. Using the scopoletin oxidation assay, we confirmed the release of increasing amounts of hydrogen peroxide by chondrocytes exposed to interleukin-1, rabbit interferon, and tumor necrosis factor alpha. Tumor necrosis factor alpha had both priming and enhancing effects on reactive oxygen intermediate production by chondrocytes. Reactive oxygen intermediates have been shown to play a significant role in matrix degradation. We suggest that reactive oxygen intermediates produced by chondrocytes play an important role in the degradation of matrix in arthritis.

Aging and osteoarthritis: the role of chondrocyte senescence and aging changes in the cartilage matrix

“…Although chondrocytes live in an environment with a low oxygen tension, they do consume oxygen and therefore exhibit aerobic metabolism78. ROS have been shown to be produced by chondrocytes in response to stimulation by cytokines and growth factors, including IL-1, TNF-α, FGF and TGF-β79-82 as well as by integrin stimulation with fibronectin fragments83. IL-1 stimulation of ROS has been associated with chondrocyte DNA damage33.…”

Apoptosis signaling pathways in osteoarthritis and possible protective role of melatonin

“…Also in articular cartilage, both the inflammatory cytokines and injurious mechanical forces can cause an elevation of superoxide production. Superoxide dismutase rapidly generates hydrogen peroxide (H 2 O 2 ) which is a weak oxidizing agent compared with O 2·− . Despite this, H 2 O 2 can give rise to ·OH in the presence of transition metals such as iron or copper via the Fenton's reaction …”

“…rapidly generates hydrogen peroxide (H 2 O 2 ) which is a weak oxidizing agent compared with O 2·− . [67][68][69] Despite this, H 2 O 2 can give rise to ·OH in the presence of transition metals such as iron or copper via the Fenton's reaction. 70 Chondrocytes produce H 2 O 2 while the inflammatory cytokines induce its production.…”

Clinical efficacy of certain Unani herbs in knee osteoarthritis: A pretest and post-test evaluation study

“…[20] Furthermore, chondrocytes are potent sources of reactive oxygen species, which may damage cartilage collagen and synovial fluid hyaluronate, the macromolecule that accounts for the viscosity of the synovial fluid. [21] Since antioxidants provide defense against tissue injury, intake of the drugs could be postulated to protect against OA and may reduce the risk of cartilage loss and disease progression in people with OA. [22] Some of the test drugs such as Piper longum [23] and Apium graveolens [24] are proven to have antioxidant property.…”