Increased hyaluronan production in the glomeruli from diabetic rats: a link between glucose-induced prostaglandin production and reduced sulphated proteoglycan

Abstract

Exposure in vivo or in vitro to elevated glucose increases production of vasoactive prostaglandins by glomeruli and mesangial cells. This study aimed to determine whether this increased prostaglandin production could provide a link with later structural changes in diabetic nephropathy. Glomerular cores were prepared from control rats and streptozotocin-diabetic rats (3 weeks' duration). Over 24 h in culture hyaluronan production from diabetic glomerular cores was higher than production from control glomerular cores whether maintained in 5.6 mmol/l glucose (105.6 +/- 15.5 vs 53.6 +/- 8.5 ng hyaluronan per 250 glomerular cores, p < 0.001); in 25 mmol/l glucose (149.3 +/- 34.8 vs 62.7 +/- 7.8 ng hyaluronan per 250 glomerular cores, p < 0.01); or in 45 mmol/l glucose (176.8 +/- 23.3 vs 102.0 +/- 17.9 ng hyaluronan per 250 glomerular cores, p < 0.01). At 5.6 mmol/l glucose, exposure in vitro to prostaglandin E2 caused an increase in hyaluronan production [maximal at 10(-9) mol/l prostaglandin E2, 237 +/- 19 vs 42 +/- 4, ng hyaluronan per 250 glomerular cores, p < 0.001 (control) and 195 +/- 7 vs 103 +/- 5, ng hyaluronan per 250 glomerular cores, p < 0.001 (diabetic)]. In both control and diabetic glomerular cores hyaluronan production was reduced significantly by the cyclooxygenase inhibitor indomethacin (10(-5) mol/l) [24.7 +/- 3.33 vs. 40.25 +/- 4.11 ng hyaluronan per 250 glomerular cores, p < 0.05 (control) and 36.5 +/- 6.25 vs 118.0 +/- 22.6, p < 0.01 (diabetic)]. A direct spectrophotometric microassay was used to determine the concentration of sulphated glycosaminoglycans derived from papain-digested glomerular core proteoglycans.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyaluronan Synthase 1 (HAS1) Requires Higher Cellular UDP-GlcNAc Concentration than HAS2 and HAS3*

“…High glucose concentrations result in increased hyaluronan production in mesangial cells (38), renal proximal tubular cells (39), renal interstitial fibroblasts (40), and vascular smooth muscle cells (41,42). Hyaluronan cumulates in the glomeruli of diabetic animals (43), and hyperglycemia induces mesangial cells to synthesize a hyaluronan coat that can recruit inflammatory cells (44,45).…”

BMP-7 Modulates Hyaluronan-Mediated Proximal Tubular Cell-Monocyte Interaction

“…Briefly, growth-arrested confluent HK-2 cells were stimulated with recombinant IL-1␤ or BMP7 in the presence of 20 Ci/ml 3 H glucosamine (Amersham Bioscineces) for 24 h. Supernatant samples were collected and treated with equal volume of 200 g/ml pronase (Sigma-Aldrich) for 24 h at 37°C to analyze HA released into the culture medium (CM fraction). The remaining cell monolayers were incubated with 10 g/ml trypsin (Sigma-Aldrich) in PBS for 10 min at room temperature to remove pericellular (protein-bound) 3 H-HA (PB fraction) before addition of an equal volume of 100 g/ml pronase for 24 h at 37°C. Finally, after trypsinization, 100 g/ml pronase was added to the cell pellet for 24 h at 37°C to solubilize the remaining cells associated 3 H-hyaluroanan (CA fraction).…”

“…Supernatant samples were collected to analyze HA released into the culture medium (CM fraction). The remaining cell layer was treated with trypsin to remove pericellular (protein-bound) 3 H-HA (PB fraction). Finally, the cell pellet after trypsinization was subjected to exhaustive protease digestion to solubilize the remaining cells-associated 3 H-HA (CA fraction).…”

“…More recently, alterations in HA synthesis within the glomerulus of the kidney have been implicated in the pathogenesis of renal diseases such as diabetic nephropathy (3,4). Although HA is not a major constituent of the normal renal corticointerstitium, it is known to be expressed around proximal tubular cells (PTC) after renal injury caused by diverse diseases (5)(6)(7)(8).…”

Hyaluronan Structures Synthesized by Rat Mesangial Cells in Response to Hyperglycemia Induce Monocyte Adhesion

“…This indicates that structures based on hyaluronan can mediate the adhesion of monocytes to resident cells. Previous studies have shown increased hyaluronan content in glomeruli isolated from diabetic animals (13) and in mesangial cells cultured in medium with a high glucose concentration (14). Exposure to high glucose concentrations also increases hyaluronan synthesis in renal proximal tubular cells (15), in renal interstitial fibroblasts (16), and in vascular smooth muscle cells (17), all of which are involved in normal kidney physiology.…”