Diabetologia (1996) 39:641-648 Diabetologia 9 Springer-Verlag1996 Effect of an aldose reductase inhibitor on type IV collagen production by human endothelial cells cultured in high glucose A. Bakillah, A.M. Grigorova-Borsos, R. Guiliot, P. Urios, M. Sternberg Equipe de Recherches sur la Biochimie et la Pharmacologie des Vaisseaux et du Rein, Facult6 de Mddecine Broussais-H6tel-Dieu, U. F. R. Biom~dicale des Saints-P~res,Universit6 de Paris V & VI, Paris, France Summary Diabetic microangiopathy is characterized by a thickening of capillary basement membranes as- sociated with type IV collagen accumulation. An in- crease in type IV collagen content of the aortic wall is also observed in macroangiopathy. In order to anal- yse the importance of the polyol pathway in the de- velopment of the collagen metabolism alterations seen in diabetic angiopathy and their prevention by aldose reductase inhibitors, we have studied the ef- fects of sorbinil on the high glucose-induced stimula- tion of type IV collagen biosynthesis in human umbil- ical vein endothelial cells. Primary cultures were ex- posed to high glucose (16.7 mmol/1), with and without 0.11 mmol/1 sorbinil, for 3 or 6 days after beginning of confluence. We measured the soluble type IV col- lagen secreted into the culture medium and the insol- uble type IV collagen accumulated in the extracellu- lar matrix and cells, by ELISA. We also studied [14C]proline incorporation into the newly synthesized collagenous and total proteins in the culture superna- tant and in the extracellular matrix and cell fraction. High glucose decreased the number of cells and in- creased the amount of type IV collagen in the culture supernatant and in the extracellular matrix and cell fi:action. It also increased proline incorporation into the newly synthesized collagenous and total proteins in the culture supernatant and in the extracellular matrix and cell fraction. Sorbinil corrected all these high glucose-induced alterations. The corrective ef- fects of sorbinil on the proliferation and on type IV collagen metabolism of endothelial cells cultured in high glucose may be attributed to prevention of poly- ol pathway dysregulation. [Diabetologia (1996) 39: 641-648] KeywoNs Diabetes mellitus, endothelial cells, glu- cose, type IV collagen, aldose reductase inhibitor, sorbinil. Diabetic microangiopathy is characterized by irregu- lar thickening of capillary basement membranes (BM). This thickening is associated with type IV Received: 1 September 1995 and in revised form: 5 December 1995 Corresponding author." Professor M. Sternberg, Equipe de Re- cherches sur la Biochimie et la Pharmacologie des Vaisseaux et du Rein, Facult6 de M6decine, 45 rue des Saints-Pbres, F-75006 Paris, France Abbreviations: AGE, Advanced glycation end product; AR, aldose reductase; ARI, aldose reductase inhibitor; BM, base- ment membrane; EC, endothelial cells; GGHG, glucosyl- galactosyl-hydroxylysyl-collagen glucohydrolase; HUVEC, human umbilical vein EC; HS, human serum; PBS, phos- phate-buffered saline; PKC, protein kinase C. collagen accumulation and a decrease in laminin and heparan-sulphate-proteoglycan concentrations [1]. Diabetic macroangiopathy is also associated with an increased type IV collagen content of the aortic wall [21. Different authors have mentioned an effect of high glucose concentration on cell proliferation [3, 4] and type IV collagen synthesis by endothelial cells (EC) 9 [5-7] or mesangial cells [8]. Several biochemical mechanisms underlying glucose-induced alterations of type IV collagen metabolism have been discussed in the literature: glucose-induced polyol pathway ac- tivation has been shown to be associated with intra- cellular sorbitol accumulation, rnyo-inositol deple- tion and altered Na +/K + ATPase activity [9-11]. In- creased protein kinase (PKC) activity may also play