Cellular membrane associated mucins in artificial urine as mediators of crystal adhesion: An in vitro enterocystoplasty model

Purpose: Cells are a major component of mucus in enterocystoplasties. We ev aluate the role of secreted mucins on cells and cellular membranes as cryst al adhesion and agglomeration mediators in artificial urine infected with P roteus mirabilis. Materials and Methods: Five human intestinal cell lines, HT29, HT29-18N2, H T29-FU, HT29-MTX, Caco-2 and 1 ureter cell line, SV-HUC-1, were incubated f or 3 hours in artificial urine with P. mirabilis (ATCC49565) in monolayer a nd scraped conditions. We isolated Triton X-100 soluble membrane proteins f rom cells to evaluate the effect of MUC2 and MUC 5AC as membrane associated proteins on crystal formation and crystal adherence. Scanning electron mic roscopy, light microscopy, Coulter Counter measurements and x-ray microanal ysis were used to evaluate crystal formation. Results: Brushite crystals were adhered to cellular surface sites rich in s ulfur as crystal agglomerates. Smaller and more numerous crystals were obse rved in the presence of scraped cells. Crystal growth and agglomeration was inhibited by the presence of MIX 5AC, whereas MUC2 had the opposite effect . Both are present on cellular membranes and are rich in sulfur. Cellular i nvasion by bacteria occurred in all cell lines. Conclusions: Membrane associated cellular secretions such as MUC2 and 5AC a re important crystal adhesion molecules on cells and have a clear effect on urease induced crystallization in vitro. MUC2 and MUC 5AC induce crystal a dhesion and mucin type dependent effects on crystal agglomeration. The effe cts of MUC2 and MUC 5AC may explain the high incidence of bladder calculi i n enterocystoplasties and emphasize the role of cellular surfaces in urine.