Neutrophil-mediated cartilage injury in vitro is enhanced by tumour necrosis factor alpha

Abstract

Neutrophil functions relevant to tissue damage are altered by cytokines such as tumour necrosis factor alpha (cachectin, TNF alpha), known to be present in inflammatory foci. In this study we examined the effect of TNF alpha on neutrophil-mediated cartilage damage in vitro. Human neutrophils were able to injure both human and bovine articular cartilage slices by degrading proteoglycan and inhibiting its synthesis. Recombinant human TNF alpha enhanced neutrophil-mediated degradation of proteoglycan, even when neutrophils were preincubated with TNF alpha and washed before incubating with cartilage. TNF alpha alone degraded proteoglycan and inhibited its synthesis. Neutrophil-mediated inhibition of proteoglycan biosynthesis was increased after incubating cartilage together with neutrophils and TNF alpha, but was unaltered when neutrophils were preincubated with TNF alpha. We conclude that TNF alpha enhances neutrophil injury to articular cartilage.

Neutrophil oxygen radical generation. Synergistic responses to tumor necrosis factor and mono/polyunsaturated fatty acids.

“…TNF is one of the cytokines which has been accredited with the property of altering phagocytic leukocyte activity. A cytokine with pleiotropic effects, TNF, can on the one hand increase resistance against infection and on the other mediate the pathophysiology associated with many diseases (1,(14)(15)(16)(17)(18)(19)(20)(21). During cell stimulation, as a result of activation of phospholipase A 2 , AA is generated.…”

Neutrophils: Molecules, Functions and Pathophysiological Aspects

“…One should emphasize the importance of neutrophil-and macrophage-derived cytokines, found in large quantities in synovial fluids [eg IL-1␤, IL-6, TNF-␣, TGF-␤, and IL-8]. In vitro, neutrophil-mediated cartilage injury is modulated by cytokines such as TNF-␣ (Kowanko et al, 1990). In vivo, the major role of TNF-␣ in the pathogenesis of RA has been demonstrated by a successful clinical trial using anti-TNF antibodies (Elliott et al, 1994).…”

Rapid degradation of articular cartilage proteoglycan by neutrophils: Comparison with macrophages and synovial fibroblasts

“…Bovine articular cartilage was isolated and cultured under sterile conditions as described previously [9]. Breifly, articular cartilage pieces were dissected aseptically from the metacarpopharyngeal joints of adult beef hocks.…”

“…Cartilage was immediately placed in Dulbecco's modified Eagle's medium (DMEM; Cell Image, Adelaide, Australia) supplemented with HEPES, antibiotics, L-glutamine and 20 % newborn calf serum (NBCS; Trace Biosciences, New Zealand), weighed and kept in an atmosphere of 37°C, 5 % CO 2 for 3-5 days before use experimentally. On the day of the experiment cartilage was incubated for 1 h at 37°C using heat aggregated human immunoglobulin G (HAGG) as previously described [9]. After incubation, cartilage was washed 3 times in Hank's balanced saline solution (HBSS: Cell Image, Adelaide, Australia), without phenol red and distributed into tubes, approximately 100 -150 mg wet weight of cartilage per tube.…”

“…It has been previously reported that the neutrophil is able to contribute to the cartilage degradative processes via the release of neutrophil elastase and oxygen derived reactive species [6][7][8]. Cytokine stimulated neutrophils inhibit proteoglycan synthesis and increase proteoglycan degradation thereby augmenting the overall degradative processes [9][10][11][12]. Although the above cell types have been closely associated with cartilage degradation, the absolute contribution of each cell type under non-inflammatory conditions has not yet been determined.…”