NAC by mouth slowed osteoarthritis in rats and held back the enzyme MMP13
This 2019 study in cultured cartilage cells and rats found that mechanical stress built up reactive oxygen species in cartilage cells, and that N-acetylcysteine (NAC) blocked this. Given by mouth to rats, NAC significantly slowed osteoarthritis and held back MMP13, the loss of type II collagen and cartilage cell death.
What they did
The researchers applied mechanical stress to cultured cartilage cells and measured reactive oxygen species (ROS), oxygen-based molecules that can damage cells, and inflammatory signals, with and without NAC. They then used a rat model of osteoarthritis, gave NAC by mouth, and examined the cartilage for signs of osteoarthritis, including MMP13, a cartilage-cutting enzyme, type II collagen and cell death.
What they found
Mechanical stress caused ROS to build up in cartilage cells in the rats, leading to cell death and osteoarthritis. In cultured cells, mechanical stress raised ROS and inflammatory signals, and NAC blocked both.
In the rats, NAC by mouth significantly slowed the development of osteoarthritis. It held back the rise in MMP13, the loss of type II collagen and cartilage cell death. NAC also reduced osteoarthritis on the rats' untreated control side, which the authors think developed changes because of altered weight-bearing.
What it can't tell us
This was a rat study; rats are not people. The abstract does not give the NAC dose, how long it was given, the number of rats, or where the cultured cells came from. It does not report glutathione measurements, so it cannot show whether NAC worked through glutathione here.
Why it matters
The other cartilage studies of NAC in this library injected it into the joint. This one gave it by mouth and still saw less osteoarthritis in rats, along with lower MMP13. It also ties mechanical stress, oxidants and MMP13 together in a living animal. Whether the same applies to people taking NAC by mouth is not something this study can answer.
The paper
- Kaneko Y, Tanigawa N, Sato Y et al. Oral administration of N-acetyl cysteine prevents osteoarthritis development and progression in a rat model. Sci Rep 2019.
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