An investigation into the mechanism of collagenolytic activity in colonic mucosa by a tissue culture method.

The process of collagenolysis and the source of collagenase liberated from different cell types in the colonic mucosa has been investigated by the lysis of collagen gels in vitro. The reconstituted collagen gel strongly reacted to periodic acid Schiff (PAS) when stained with combined alcian blue-PAS, indicating the presence of glycoprotein with neutral sugars in the collagen gel. Colonic explants of rabbits produced visible collagenolysis. An area of alcian blue stained gel was seen replacing the usual PAS staining around the area of the lysis. Several histochemical methods revealed that the columnar cells had multiplied with high enzymatic activity and penetrated the collagen gel where collagenolysis took place. The action of several proteolytic enzymes on collagen gel showed that ficin caused lytic activity, even though collagen is resistant to most proteolytic enzymes. Papain, pepsin and trypsin altered composition of collagen gel from neutral mucopolysaccharide to acid mucopolysaccharide. Collagenase and pronase at low concentration were found to cause extensive collagenolysis. The synthesis and breakdown of collagen is a desirable balanced process in the remodelling of connective tissue. This dynamic equilibrium may be achieved through the subtle interplay of cells liberating and inhibiting collagenase.