Glutamine almost fully prevented cartilage cell death under heat and nitric oxide

What they did

Researchers grew cartilage cells from rabbit joints and treated them for 12 hours with glutamine at 0 to 20 mM. They then stressed the cells with heat (43°C for up to 120 minutes) or with sodium nitroprusside, which releases nitric oxide. Some cells were also given quercetin, which blocks HSP70, a heat shock protein that helps cells survive stress. They measured HSP70, cell survival and apoptosis, a programmed form of cell death.

What they found

Glutamine increased HSP70 under stress, more so at higher doses, but did not raise HSP70 on its own without stress. Heat and nitric oxide sharply reduced cell survival, and glutamine almost completely prevented that loss.

Blocking HSP70 with quercetin significantly reduced glutamine's protection. Glutamine also made the cells resistant to nitric oxide-induced apoptosis. The authors suggest HSP70 may carry glutamine's protective effect.

What it can't tell us

These were rabbit cells in a dish, not human cartilage. The doses were set in culture medium, so the study cannot say what glutamine taken by mouth would do in a joint. The abstract does not report glutathione measurements, so it does not show whether glutathione played any part.

Why it matters

This study shows glutamine protecting cartilage cells, but through a heat shock protein rather than glutathione as far as the abstract reports. It is a reminder that glutamine does more than one job in cartilage cells. The glutathione link for glutamine comes from a different study in this library (Stegen 2020).

The paper

1. Tonomura H, Takahashi KA, Mazda O et al. Glutamine protects articular chondrocytes from heat stress and NO-induced apoptosis with HSP70 expression. Osteoarthritis Cartilage 2006.
   PMID 16480901DOI 10.1016/j.joca.2005.12.008

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