Eosinophils adhere to vascular cell adhesion molecule-1 via podosomes.
Vascular cell adhesion molecule (VCAM)-1 supports specific eosinophil adhesion via alpha4beta1 integrin. We tested the hypothesis that adhesive contacts formed by eosinophils on VCAM-1 are different from focal adhesions formed by adherent fibroblasts. Eosinophils adherent on VCAM-1 formed punctate adhesions that fit the criteria for podosomes, highly dynamic structures found in adherent transformed fibroblasts, osteoclasts, and macrophages. The structures contained beta1 integrin subunit, phosphotyrosine-containing proteins, punctate filamentous actin, and gelsolin, a podosome marker. In contrast, nontransformed fibroblasts on VCAM-1 formed peripheral focal adhesions that were positive for alpha4, beta1, phosphotyrosine, vinculin, talin, and paxillin; negative for gelsolin; and associated with microfilaments. Phorbol myristate acetate or tumor necrosis factor-alpha and interleukin-5 stimulated podosome formation in adherent eosinophils. Because podosomes in tumor cells are associated with extracellular matrix degradation, we analyzed the VCAM-1 layer. VCAM-1 was lost under adherent eosinophils but not under adherent fibroblasts. This loss was inhibited by the metalloproteinase inhibitor ortho-phenanthroline and correlated with expression and podosome localization of a membrane-tethered metalloproteinase, a disintegrin and metalloproteinase domain 8. Podosome-mediated VCAM-1 clearance may be a mechanism to regulate eosinophil arrest and extravasation in allergic conditions such as asthma.
Johansson
Mats W
MW
Department of Medicine, University of Wisconsin, 4285A, Medical Sciences Center, 1300 University Avenue, Madison, WI 53706-1532, USA. mwj@medicine.wisc.edu
Lye
Ming H
MH
Barthel
Steven R
SR
Duffy
Allison K
AK
Annis
Douglas S
DS
Mosher
Deane F
DF
D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D001249:Asthma / Q000378:metabolism / Q000473:pathology*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D021961:Cell Membrane Structures / Q000378:metabolism / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D019483:Disintegrins / Q000378:metabolism; D004804:Eosinophils / Q000187:drug effects / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D018260:Gelsolin / Q000378:metabolism; D006801:Humans; D039041:Integrin alpha4beta1 / Q000378:metabolism*; D015848:Interleukin-5 / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D020784:Matrix Metalloproteinase 8 / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism; D051419:Paxillin; D010618:Phenanthrolines / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D012220:Rhinitis / Q000378:metabolism / Q000473:pathology*; D016608:Talin / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism*; D016596:Vinculin / Q000378:metabolism
D000199:Actins; D003598:Cytoskeletal Proteins; D019483:Disintegrins; D018260:Gelsolin; D039041:Integrin alpha4beta1; D015848:Interleukin-5; C496061:PXN protein, human; D051419:Paxillin; D010618:Phenanthrolines; D010750:Phosphoproteins; D016608:Talin; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D016596:Vinculin; C001635:ferroin; D019000:Phosphotyrosine; D020784:Matrix Metalloproteinase 8; D013755:Tetradecanoylphorbol Acetate