Effects of selectin-sialyl Lewis blockade on mesenteric microvascular permeability associated with cardiopulmonary bypass

Capillary Leakage in Cardiac Surgery with Cardiopulmonary Bypass

Cardiopulmonary bypass causes a systemic inflammatory response, which can lead to capillary leak syndrome. In 15 adults undergoing elective cardiac surgery with cardiopulmonary bypass, we determined the volume and peak time of capillary leakage from the measurements of extracellular fluid volume and circulating blood volume taken preoperatively, at various intervals up to 24 hours after surgery, and on the 7th postoperative day. Extracellular fluid volume rose from 15.5 ± 2.7 Lpreoperatively to a peak 4 hours after surgery of 18.3 ± 3.2 L and remained elevated at 24 hours. Circulating blood volume fell from 4.10 ± 0.68 L preoperatively to 3.20 ± 0.58 L at the end of surgery. Fluid administered intraoperatively did not raise the circulating blood volume. Intraoperative fluid balance was positive at 2.62 ± 0.72 L but negative at all time points postoperatively. There was significant postoperative capillary leakage, increasing from 4.7% ± 2.3% of body weight at the end of surgery to a peak 4 hours later of 5.4% ± 2.0% and falling to 2.8% ± 3.3% at 24 hours. This knowledge of the pattern of change in capillary leakage after cardiac surgery with cardiopulmonary bypass might serve as a valuable guide for postoperative management.

The anti-inflammatory effects of a selectin ligand mimetic, TBC-1269, are not a result of competitive inhibition of leukocyte rolling in vivo

Selectins and their ligands support leukocyte rolling, facilitating the subsequent firm adhesion and migration that occur during inflammation. TBC-1269 (Bimosiamose), a structural mimetic of natural selectin ligands, inhibits P-, E-, and L-selectin in vitro, has anti-inflammatory effects in vivo, and recently underwent phase II clinical trials for childhood asthma and psoriasis. We studied whether the anti-inflammatory effects of TBC-1269 could be related to leukocyte rolling in vivo. Although TBC-1269 inhibited rolling of a murine leukocyte cell line on murine P-selectin in vitro and thioglycollate-induced peritonitis in vivo, it did not alter leukocyte rolling in mouse cremaster venules. TBC-1269 reduced neutrophil recruitment in thioglycollate-induced peritonitis in wild-type and P-selectin-/- mice but not in E-selectin-/- mice. We suggest that the in vivo effects of TBC-1269 may be mediated through E-selectin but do not appear to involve leukocyte rolling.

The discovery, biology, and drug development of sialyl Lea and sialyl Lex

The discoveries of sialylated, fucosylated lacto-, and neolacto-type carbohydrate structures were accomplished with the aid of analytical methods and monoclonal antibodies such as the immunostaining of thin layer chromatograms. Based on the use of such antibodies, these structures, notably sialyl Le(a) and sialyl Le(x), were demonstrated to be highly expressed in many malignant cancers. A diagnostic assay using one of these antibodies (CA19-9) is now established as one of the more commonly used assays for pancreatic and gastrointestinal cancers worldwide. Upon further study, several laboratories have demonstrated that the level of expression of these carbohydrate tumor markers is also positively correlated with patient survival and is a prognostic indicator of metastatic disease. Concurrent with this finding, both sialyl Le(a) and sialyl Le(x) were shown to bind to a family of carbohydrate-binding proteins involved in the extravasation of cells from the bloodstream, called the selectins. Thus, sialyl Le(a) and sialyl Le(x) expressed on cell surfaces play functional roles in medical conditions that require extravasation of cells from the bloodstream which include a wide range of inflammatory diseases and cancer metastasis. Many studies have confirmed the function of sialyl Le(a) and sialyl Le(x) in animal models of these diseases and the inhibition of binding of sialyl Le(a) and sialyl Le(x) to the selectins is a validated drug target in the pharmaceutical industry. Thus, a new class of drugs, arising from the field of glycobiology, is based on the rational design of small molecule drugs that mimic the structures sialyl Le(a) and sialyl Le(x) and can potently inhibit their functional binding to the selectins.