Some structural determinants of the antiproliferative effect of heparin‐like molecules on human airway smooth muscle

Abstract

1 Accumulation of airway smooth muscle (ASM) and its infiltration by mast cells are key pathological features of airway remodelling in asthma. Heparin, a major component of mast cell granules, inhibits ASM proliferation by an unknown mechanism. Here, unfractionated heparins and related glycosaminoglycans having structurally heterogeneous polysaccharide side chains that varied in molecular weight, sulphation and anionic charge were used to identify features of the heparin molecule that were required for its antiproliferative activity in cultured human ASM cells. 2 Proliferation induced by 10% fetal bovine serum (FBS) was abrogated by two unfractionated commercial heparin preparations (Sigma and Multiparin) and this effect was reproduced with each of three low-molecular weight heparin preparations (3, 5 and 6 kDa, respectively), demonstrating that antiproliferative activity resided in at least a 3 kDa heparin fraction. 3 N-desulphated 20% re-acetylated (N-de) heparin (anticoagulant) and O-desulphated heparin (Ode) (non-anticoagulant) fractions also inhibited FBS-dependent proliferation (rank potency: Sigma heparin4O-de4N-de) suggesting that the antiproliferative action of heparin involved N-sulphation but was independent of its anticoagulant activity. 4 Other sulphated molecules with variable anionic charge (dextran sulphate, fucoidan, chondroitin sulphates A or B, heparan sulphate) inhibited proliferation to varying degrees, as did the nonsulphated molecules hyaluronic acid and poly-L-glutamic acid. However, nonsulphated dextran had no effect. 5 In summary, attenuation of FBS-dependent proliferation of human ASM by heparin involves but does not depend upon sulphation, although loss of N-sulphation reduces antiproliferative activity. This antiproliferative effect is independent of anionic charge and the anticoagulant actions of heparin.

Effects of decorin and biglycan on human airway smooth muscle cell proliferation and apoptosis

“…Some information is available in the literature on the effect of GAGs on cell proliferation. Several investigators have reported that heparin and heparin-like molecules can reduce proliferation of HASMCs (9,19). In his experiments, Kanabar et al (19) showed that chondroitin sulfate A and B had less marked effects despite concentrations much greater (up to 10 mg/ml) than those used in the current experiment.…”

“…Versican, the large aggregating PG, can either enhance or decrease vascular smooth muscle proliferation, depending on the specific versican isoform (37). Heparin, the glycosaminoglycan side chain bound to basement membrane PG, has been shown to have antiproliferative effects on human and canine ASM (9,19).…”

Decreased hyaluronan in airway smooth muscle cells from patients with asthma and COPD

“…Furthermore, in COPD patients [34] or elastase-induced emphysema [35], treatment with HA had beneficial effects. It is of interest that two other GAG, heparin and HS, have also been reported to be beneficial during asthma therapy by a mechanism of action that is not directly related to their anticoagulant property [36].…”

Pharmacology of Heparin and Related Drugs

“…Indeed, inhibition of vascular smooth muscle proliferation is a long established property of heparin (Clowes and Karnowsky, 1977), unrelated to anticoagulant activity (Guyton et al, 1980), that has since been described in airway smooth muscle as well (Kilfeather et al, 1995;Okona-Mensah et al, 1998;Kanabar et al, 2005). Heparin acts as a potent competitive inhibitor of inositol 1,4,5-triphosphate-dependent calcium release from the endoplasmic reticulum (Ghosh et al, 1988), an effect that is considered to underlie the inhibition of human mast cells that has been described in vitro (Inase et al, 1993) and found to be independent of anticoagulant activity (Ahmed et al, 1997).…”