Matrix metalloproteinase-13, also called collagenase-3. Of all the enzymes that cut collagen, it has the highest activity against the type II collagen that holds cartilage together.
Type II collagen is three protein strands wound into a rope. MMP13 clamps on and cuts all three at one spot, leaving a three-quarter piece and a one-quarter piece, then trims the shorter piece further.
Once the rope is cut, it unwinds and other enzymes can finish the job. It broke down type II collagen at least ten times faster than MMP-1, its nearest relative.
Skin renews its collagen over a few years. Cartilage collagen is close to permanent. That's good news while it's intact, and bad news once an enzyme starts cutting it, because the cells can't rebuild the mesh at anything like the rate it can be lost.
That's why researchers single MMP13 out. Aggrecan, the cushioning gel in cartilage, can recover. The collagen scaffold, once cut, is considered irreversible, so the job is to keep the collagen you have.
In healthy ankle cartilage from donors young and old, the collagen-cutting enzymes were present but didn't rise with age, and collagen stayed in balance.
Aurich 2002When cartilage cells were provoked with an inflammatory signal or collagen fragments, cells from older donors made significantly more MMP13.
Forsyth 2005Inflammation, oxidative stress, calcium crystals, a disrupted body clock in the cells, higher blood sugar and high leptin have each raised MMP13 in human cartilage cells. Some of the most recent work comes from Auckland.
Snelling 2016 · Rong 2019 · Rong 2019 · Primrose 2023 · Jain 2024Two groups show human cartilage cells make it, and that it cuts type II collagen fast.
Mitchell 1996 · Reboul 1996The 117-year half-life, and the finding that older cells over-react.
Verzijl 2000 · Forsyth 2005Which ingredients have been studied against MMP13, and how a technology was built around them.