Decreased leukocyte recruitment in the mesenteric microcirculation of rats with cirrhosis is partially restored by treatment with peginterferon: an in vivo study

Protein-bound uremic toxins stimulate crosstalk between leukocytes and vessel wall

Leukocyte activation and endothelial damage both contribute to cardiovascular disease, a major cause of morbidity and mortality in CKD. Experimental in vitro data link several protein-bound uremic retention solutes to the modulation of inflammatory stimuli, including endothelium and leukocyte responses and cardiovascular damage, corroborating observational in vivo data. However, the impact of these uremic toxins on the crosstalk between endothelium and leukocytes has not been assessed. This study evaluated the effects of acute and continuous exposure to uremic levels of indoxylsulfate (IS), p-cresylsulfate (pCS), and p-cresylglucuronide (pCG) on the recruitment of circulating leukocytes in the rat peritoneal vascular bed using intravital microscopy. Superfusion with IS induced strong leukocyte adhesion, enhanced extravasation, and interrupted blood flow, whereas pCS caused a rapid increase in leukocyte rolling. Superfusion with pCS and pCG combined caused impaired blood flow and vascular leakage but did not further enhance leukocyte rolling over pCS alone. Intravenous infusion with IS confirmed the superfusion results and caused shedding of heparan sulfate, pointing to disruption of the glycocalyx as the mechanism likely mediating IS-induced flow stagnation. These results provide the first clear in vivo evidence that IS, pCS, and pCG exert proinflammatory effects that contribute to vascular damage by stimulating crosstalk between leukocytes and vessels.

Thalidomide decreases intrahepatic resistance in cirrhotic rats

Increased intrahepatic resistance (IHR) within cirrhotic liver is caused by increased endotoxemia, cytokines tumor necrosis factor-alpha (TNF-alpha), vasoconstrictor thromboxane A(2) (TXA(2)), and disrupted microvasculatures. We evaluated the effects of thalidomide-related inhibition of TNF-alpha upon the hepatic microcirculation of cirrhosis in rats. Portal venous pressure (PVP), hepatic TNF-alpha, expression of thromboxane synthase (TXS), and leukocyte common antigen (LCA) were measured in bile-duct-ligated (BDL) rats receiving 1 month of thalidomide (BDL-thalido rats). Portal perfusion pressure (PPP), IHR, and hepatic TXA(2) production were measured in the isolated liver perfusion system. Intravital microscopy was used to examine hepatic microvascular disruptions. In BDL-thalido rats, PVP, PPP, IHR, hepatic TXA(2) and TNF-alpha, hydroxyproline content, expression of TXS and LCA, and LPS-induced leukocyte recruitment were significantly decreased. Conversely, hepatic microvascular density and perfused sinusoids were significantly increased. Thalidomide decreased PVP and IHR by reducing hepatic TXA(2) and improving hepatic microvascular disruptions in rats with biliary cirrhosis.