Study On The Mechanism Of Interaction Between CD11b And Lactose Derivative Gu-4

Inflammation is a kind of innate protection measure to fight against noxious stimuli and facilitate the healing process.But it presents as a double-edged sword to organisms,it can not only impair local tissue damage,but also cause systemic responses with excess or inadequate inflammatory reaction.From our previous study,we found that lactose derivative Gu-4 had an apparently therapeutical effect in animal models including rheumatoid arthritis and sepsis.Gu-4 not only targetedly suppressed the adhesion between leucocytes and endothelial cells,but also blocked the signaling pathway.While the molecular mechanism of the interruption effect is still unknown.That is to say,there are two problems remain unknown:the target orientation for the interation of CD11b with Gu-4 and the potential importance of CDllb glycosylation for Gu-4 binding in the adhesion process.First of all,we expressed recombinant proteins of 3 extracellular domains of CD11b in eukaryotic system.Then we adopted the surface plasma resonance(SPR)technology to the study of the binding kinetics between Gu-4 and integrin CD11b,detecting the target orientation for the interaction of CD11b with Gu-4.These results showed that I domain and EGF domain are both likely to be the target structures and own a dual-role in suppressing adhesion and blocking the signal transmission in the interaction of Gu-4 and CD11b.Secondly,we investigated the role of CD11b glycosylation on its interaction with Gu-4 in vitro.Analyses of flow cytometry and confocal microscopy demonstrated that the binding capability was weakening in response to the suppression of CDllb glycosylation by specific inhibitor.It suggested that the combination between CD11b and Gu-4 was affected with the suppression of CDllb glycosylation.And glycosylation mainly affected the expression of the amount of CD11b molecules on cell membrane from further study.Reducing or blocking the adhesion between white blood cells and endothelial cells to achieve the goal of preventing inflammation disease progression is a novel and different way from traditional treatment strategies.Carbohydrate compounds have virtues of good biological compatibility,non-toxic and low toxicity.The anti-inflammatory carbohydrates based on the adhesion inhibition have promising characteristics.Our study indicates the key domains in suppressing adhesion and blocking the signal transmission in the interaction of Gu-4 and CD11b,making more explicit the anti-inflammatory mechanism.It also expands the specific targets and structures for further pharmaceutical design and synthesis for anti-inflammatory medications.