Effects of inhaled low molecular weight heparin on airway allergic inflammation in aerosol-ovalbumin-sensitized guinea pigs

Low molecular weigh, heparin (LMWH) possesses multiple nonanticoagulant pro perties. In the present study, we observed its anti-airway allergic inflamm atory effects by bronchoalveolar lavage in guinea pigs. Guinea pigs were se nsitized by repeatedly inhaling aerosolized ovalbumin. LMWH (400 u/l, 800 u /l), dexamethasone (1.2 mg/l) or vehicle (normal saline) was inhaled for 7 days. Then the animals were sacrificed under anesthesia and then lavaged wi th ice-cold Hank's buffer immediately; bronchoalveolar lavage fluid (BALF) was prepared 24 h after the animals were challenged by antigen exposure. Th e effects of LMWH on total cell counts, absolute eosinophil counts and cell catalogues in BALF were studied; effects on the activity of eosinophil per oxidase (EPO) and the contents of histamine and eosinophil cationic protein (ECP) in BALF supernatant were detected. Our results showed that compared with the vehicle group, LMWH at 400 u/l and 800 u/l could significantly red uce total cell counts, absolute eosinophil counts and percentage of eosinop hils in BALF (P<0.05 and P<0.01, respectively); LMWH at 800 u/l markedly in hibited the activity of EPO in BALF supernatant (P<0.05); LMWH at 400 u/l a nd 800 u/l remarkably reduced the content of histamine in BALF supernatant (P<0.05 and P<0.01, respectively), LMWH at 800 u/l decreased the content of ECP (P<0.05) significantly. It suggested that LMWH exerted anti-airway all ergic inflammatory action by inhibiting infiltration of inflammatory cells and reducing release of inflammatory mediators, as well as antagonizing the ir activities, and that LMWH could be developed as a potential anti-bronchi al asthmatic drug.