Mouse polymorphonuclear granulocyte binding to extracellular matrix molecules involves β1 integrins

Abstract

The mechanism of adhesion of purified mouse polymorphonuclear granulocytes (PMN) to extracellular matrix proteins characteristic of basement membranes and the interstitium has been investigated and compared with the adhesion of a mouse progranulocytic cell line, 32DC13, and a mouse monocytic cell line, WEHI 78/24. All three cell types bound specifically to fibronectin and vitronectin to different degrees under different cellular activation states. 32DC13 bound to fibronectin and vitronectin strongly, and this binding increased upon cellular activation with phorbol 12-myristate-13-acetate (PMA) but not with formyl-Met-Leu-Phe. Only 32DC13 showed significant binding to laminin-1. By contrast, WEHI 78/24 and PMN bound only fibronectin and vitronectin; this binding was weak and was altered only marginally upon activation with PMA. In the case of WEHI 78/24, a slight increase in adhesion both to fibronectin and to vitronectin was observed after cellular activation with PMA, while PMN adhesion to both substrates was slightly reduced. The mechanism of binding to fibronectin and vitronectin was similar in the three cell types. The integrin alpha5 beta1 mediated fibronectin adhesion, demonstrating for the first time the existence of a functionally active beta1 integrin on mouse PMN. Vitronectin binding was mediated by alpha(v) beta3, as demonstrated by the ability of alpha(v)-specific cyclic L-Arg-L-Gly-L-Asp-D-Phe-L-Val (RGDfV) peptide (EMD66203), and anti-beta3 antibody to inhibit cell adhesion. 32DC13 adhesion to laminin-1 was via the alpha6 beta1 integrin. None of the three cell types tested bound to the basement membrane proteins collagen type IV and perlecan, or to the interstitial stromal constituents tenascin, collagen types I, V and VI. Interestingly, perlecan and collagen type IV were found to repel all three cell types. The relative inability of PMN, WEHI 78/24, and 32DC13 to bind to extracellular matrix proteins characteristic of basement membranes and their ability to bind inflammatory markers of the interstitium is discussed with respect to leukocyte extravasation processes.

Differential Effects of CD18, CD29, and CD49 Integrin Subunit Inhibition on Neutrophil Migration in Pulmonary Inflammation

“…Behzad et al (31), studying CD18-independent (induced by S. pneumoniae) neutrophil migration in rabbit lung, presented compelling evidence that interstitial fibroblasts play a crucial role in providing directional information to migrating neutrophils. They found that ϳ70% of the surface of migrating neutrophils was in close proximity to fibroblasts or matrix proteins; since neutrophil adhesion to these substrates is CD29 dependent (35), this is a likely explanation for the effect of the CD29 mAb in our studies. Moreover, Werr et al (34) showed that neutrophil migration in extravascular tissue of rat mesentery in response to topical application of chemoattractant (platelet-activating factor (PAF)) was markedly reduced by HM␤1-1.…”

“…Neutrophils express CD29 integrins, and these are known to be involved in adhesion and migration of neutrophils across extracellular matrix proteins (34,35,48,49), and may therefore facilitate migration of neutrophils through the alveolar interstitium. Neutrophil migration to both LPS and KC was markedly reduced by the anti-CD29 mAb HM␤1-1.…”

“…Neutrophil adhesion to fibroblasts is mediated by the ␤ 1 integrin CD29 (32)(33)(34). This forms heterodimers with the ␣ integrin, CD49, and neutrophils have been shown to express CD49d, e, and f at levels sufficient to mediate adhesion to extracellular matrix proteins (35)(36)(37). Recent data have shown extravasated neutrophils to express CD49b and that a blocking mAb inhibited neutrophil locomotion in extravascular tissue in vivo (49).…”

P-selectin and MAC-1 mediate monocyte rolling and adhesion to ECM-bound platelets under flow conditions

“…After vascular injury extracellular matrix (ECM) is exposed to flowing blood. Adhesion and subsequent functional modulation of neutrophils and monocytes on matrix proteins is only studied in static adhesion assays [3,13,14]. This process under flow conditions remains to be identified.…”

Venular basement membranes contain specific matrix protein low expression regions that act as exit points for emigrating neutrophils

“…The mechanism by which this occurs in vivo is, however, unknown and although in vitro studies have frequently implicated leukocyte proteases in this response (17), histological studies have consistently failed to identify defects in the structure of the BM at sites of leukocyte migration (16,18). Neutrophils, in particular those that have undergone a transmigration step, express functionally important levels of integrins such as α 2 β 1 (19,20) and α 6 β 1 (21)(22)(23), receptors for collagen IV and laminins, respectively. This strongly suggests that adhesive interactions between neutrophils and BM constituents may play an important role in guiding neutrophils through the venular BM.…”