Treatment with β-SQAG9 prevents rat hepatic ischemia-reperfusion injury

Selectin inhibitors and their proposed role in ischemia and reperfusion

The selectin family of cellular adhesion molecules plays an important role in the cellular infiltration and molecular signaling associated with ischemia/reperfusion (I/R). Selectins are essential in the recruitment and infiltration of leukocytes to sites of inflammation, and consequently, selectin blockade represents an important area of current research in the potential alleviation of the cell-mediated injury associated with I/R. Previously, treatments targeted at only a single selectin have proven ineffective, due to compensation by uninhibited cell-adhesion molecules. However, pan-selectin antagonists - those inhibitors capable of blocking the actions of all three selectins - have demonstrated great potential in blocking the initial events in the leukocyte-endothelium adhesion cascade. A number of therapeutics have been developed, with the most promising results demonstrated by a class of non-oligosaccharide, small-molecule selectin antagonists. TB-1269 and OC-229 are two of the most promising of inhibitors in this class - they are capable of binding all three selectins, they have been demonstrated to reduce neutrophil infiltration following ischemia/reperfusion, and they have been associated with reduced tissue damage in experimental animal models of ischemia/reperfusion involving the liver, the heart, the kidneys, and the whole body. Furthermore, TBC-1269 has recently undergone successful phase I and phase IIa clinical trials for asthma and psoriasis. Though the timing of selectin inhibition is essential in attenuating leukocyte infiltration and cell-mediated injury, the transient blockade of selectin function, in a well-controlled setting, could be an extremely beneficial intervention in ischemia/reperfusion injury.

Protective mechanism of beta-SQAG9 liposome, a sulfonoglycolipid extracted from sea urchin intestines, against hepatic ischemia reperfusion injury

We previously reported that beta-SQAG9 liposome, a sulfonoglycolipid extracted from sea urchin intestines, had a protective effect against hepatic ischemia reperfusion (I/R) injury. In this study, we made a detailed investigation of this protective effect and its mechanism. Rats were pretreated either with beta-SQAG9 liposome (treated group) or with phosphate-buffered saline solution (control group). Thereafter, they were subjected to partial hepatic I/R. The serum levels of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase were measured, and histological damage was evaluated with hematoxylin and eosin staining. To investigate the protective mechanism of beta-SQAG9 liposome on I/R injury, the serum levels and the tissue messenger RNA levels of TNF-alpha and IL-1beta were measured, and polymorphonuclear neutrophil (PMN) infiltration was histologically evaluated by immunohistochemistry. Moreover, to investigate an interaction between beta-SQAG9 liposome and L-selectin on PMNs, flow cytometric analysis and immunofluorescence were performed. beta-SQAG9 liposome reduced the hepatic I/R injury. The pretreatment with beta-SQAG9 liposome reduced the PMN infiltration into the liver parenchyma. On the other hand, there was no apparent difference in the serum levels and the tissue messenger RNA levels of the proinflammatory cytokines between the two groups. Thus, beta-SQAG9 liposome might reduce the hepatic I/R injury by inhibition of the PMN infiltration into the liver parenchyma, which was independent of the regulation of cytokine production. Moreover, we demonstrated that beta-SQAG9 liposome specifically bound to L-selectin on PMN cell surface, which mediated the PMN infiltration. beta-SQAG9 liposome might competitively antagonize L-selectin on PMNs and suppress the subsequent PMN infiltration, resulting in the reduction in I/R injury.