Hyaluronan modifies inflammatory response and peritoneal permeability during peritonitis in rats

The effect of high-molecular-weight hyaluronan (HA) on peritoneal and systemic inflammation and peritoneal permeability to water and solutes was studied during endotoxin-induced peritonitis in rats. Acute peritonitis was induced by adding lipopolysaccharide (LPS) to the dialysis fluid (Dianeal 3.86; Baxter Healthcare, Ireland, Castlebar). HA was added to the dialysis solution in a concentration of 10 mg/dL. During 4- and 8-hour dwells of the dialysis fluid, we studied the intensity of peritoneal (dialysate) and systemic (blood) inflammation (dialysate cell count and differential, cytokine and HA levels), as well as the transperitoneal transport of solutes and water. In rats, the addition of LPS to the dialysis fluid induced changes in inflammatory reaction and transperitoneal transport similar to those seen in continuous ambulatory peritoneal dialysis patients with peritonitis. During peritonitis, the addition of HA to the dialysis fluid reduced the loss of ultrafiltration, which resulted in a greater peritoneal creatinine clearance during the 8 hours of dwell (29.9 ± 6.7 mL/8 h in the HA-LPS group versus 19.7 ± 7.8 mL/8 h in the LPS group; P < 0.05). Dialysate interferon-γ (INF-γ) levels during peritonitis were greater in HA-treated animals (536.8 ± 296.6 pg/mL in the HA-LPS group versus 169.8 ± 137.8 pg/mL in the LPS group; P < 0.05). Dialysate elastase activity increased during peritonitis (44.4 ± 9.3 versus 14.2 ± 4.1 U/mL in peritonitis-free rats); during peritonitis, the increase in dialysate elastase activity was less pronounced in the rats that had HA in the dialysate (27.3 ± 4.1 U/mL versus the LPS group; P < 0.01). We conclude that HA added to the dialysis fluid reduces loss of ultrafiltration during peritonitis in rats. In the presence of HA dialysate, INF-γ levels during peritonitis increased, whereas elastase activity decreased; these changes might improve the peritoneal immune reaction during peritonitis and at the same time prevent peritoneal membrane injury.