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Mouse polymorphonuclear granulocyte binding to extracellular matrix molecules involves beta 1 integrins
M Frieser1, R Hallmann, S Johansson
1Institute for Experimental Medicine, University of Erlangen-Nürnberg, Germany.
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.
Insights
Mouse immune cells (PMN) and cell lines (32DC13, WEHI 78/24) show specific adhesion to fibronectin and vitronectin, mediated by integrins alpha5 beta1 and alpha(v) beta3, respectively. They do not bind basement membrane proteins, impacting leukocyte extravasation.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Leukocyte adhesion to extracellular matrix (ECM) is crucial for inflammatory and immune responses.
- Understanding the specific integrin-mediated interactions of different leukocyte types with ECM proteins is vital for deciphering cell migration mechanisms.
Purpose of the Study:
- To investigate and compare the adhesion mechanisms of mouse polymorphonuclear granulocytes (PMN), 32DC13, and WEHI 78/24 cell lines to various ECM proteins.
- To identify the specific integrins involved in these adhesion processes.
- To relate these findings to leukocyte extravasation.
Main Methods:
- Adhesion assays were performed using purified mouse PMN, 32DC13, and WEHI 78/24 cell lines.
- Cells were tested for binding to fibronectin, vitronectin, laminin-1, collagen type IV, and perlecan under varying activation states.
- Inhibitory peptides (RGDfV) and antibodies were used to determine the integrin mechanisms involved.
Main Results:
- All three cell types exhibited specific binding to fibronectin and vitronectin, with varying affinities and responses to activation (PMA).
- 32DC13 cells showed significant binding to laminin-1, mediated by alpha6 beta1 integrin.
- PMN and WEHI 78/24 cells primarily adhered to fibronectin (via alpha5 beta1) and vitronectin (via alpha(v) beta3), with limited changes upon activation.
- None of the cell types bound to collagen type IV or perlecan; these proteins appeared to repel the cells.
Conclusions:
- Mouse PMN and tested cell lines utilize specific integrins (alpha5 beta1, alpha(v) beta3) for adhesion to interstitial ECM proteins like fibronectin and vitronectin.
- The limited binding to basement membrane proteins suggests a role in regulating leukocyte extravasation.
- These findings highlight differential integrin usage and ECM interactions relevant to leukocyte trafficking in inflammatory processes.