Journal Club: Wound Healing/Ions

Thursday, October 10, 2013

Presentation: “Adding In-salt to Injury: Tissue Damage Detection by Osmotic Surveillance”

Presenter: Carlos Rojo <(second-year BMS student)

Paper: Enyedi B., et al. “Tissue damage detection by osmotic surveillance.” Nat Cell Biol. <2013 Sep;15(9):1123-30.

In a nutshell:

Generally, even we non-physicians know how to dress a small wound.  Wash the area with soap and water, apply an antibiotic treatment cream and add a bandage if the area is likely to be exposed to dirt.

Sometimes you get a cut or sore that just won’t heal, and then you realize that we don’t actually understand everything about the process of wounds healing.

On a cellular level, it’s understood that wounds are breaches in the defensive epithelial cell layer. 

Some of these cells die and send out death signals to immune cells, which leads to an inflammatory response.  Eventually, if all goes well, the barrier is as good as new again.

But the timing doesn’t quite make sense.  The immune cells can get to the wound pretty quickly, so is there another method of wound detection?  The authors thought about it and noted that there is normally a chemical gradient across barriers that can be disrupted by a wound.  They then asked if cells can detect these ionic changes after an injury.

The authors nicked the tails of zebrafish, which are great models for this process, in part because of their near-transparent flesh.  Then they put the fish either in hypotonic or isotonic solutions.  There was a greater wound-healing response in the hypotonic solution. 

In other words, when the ion concentrations were different inside and outside the wound, there was more efficient immune activation.  This suggests that the differences in ion concentrations allowed for wound detection. 

More work is needed to understand this mechanism, but this understanding can potentially help us improve how we treat wounds.