title: Mechanical deformation promotes secretion of IL-1 alpha and IL-1 receptor antagonist.
abstract: Both IL-1 alpha and IL-1 beta lack an N terminus secretory sequence, and the mechanism of secretion of these pleiotropic cytokines is incompletely understood. The epidermis contains large quantities of IL-1 alpha in keratinocytes, which may play a role in inducing endothelial adhesion molecules and promoting extravasation of leukocytes. Here we report that mechanical deformation of human keratinocytes leads to rapid release of IL-1 alpha, possibly through transient disruptions in the plasma membrane. Using a device that precisely controls the amplitude of strain on the culture substrate, we found by pulse-chase analysis, Western analysis, and ELISA that the release of IL-1 alpha is dependent on the amplitude of the strain. A cyclic strain of 14% released a small but significant quantity of IL-1 alpha, while strains of 33% released 66 +/- 9% of cytoplasmic IL-1 alpha over 1 h (p < 0.001). Release of IL-1 alpha was accompanied by rapid release of large stores of IL-1R antagonist, approximately 25 to 30 times greater by mass than the quantity of IL-1 alpha released, but only a small fraction of cytoplasmic lactate dehydrogenase. Media conditioned by mechanically stimulated keratinocytes induced expression of E-selectin by human vascular endothelial cells; induction of E-selectin was completely inhibited by an Ab to IL-1 alpha. Therefore, mechanical strain promotes the secretion of IL-1 alpha, and deformation of keratinocytes in the epidermis may activate vascular endothelium through mechanically released IL-1 alpha. This pathophysiologic mechanism may play a role in the anatomic localization of some inflammatory skin diseases, such as psoriasis, which occurs more commonly in locations where the dermis is subjected to repetitive stretch or trauma.
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. RTLEE@BICS.BWH.HARVARD.EDU
authors.forename: R T
authors.initials: RT
authors.lastname: Lee
authors.forename: W H
authors.initials: WH
authors.lastname: Briggs
authors.forename: G C
authors.initials: GC
authors.lastname: Cheng
authors.forename: H B
authors.initials: HB
authors.lastname: Rossiter
authors.forename: P
authors.initials: P
authors.lastname: Libby
authors.forename: T
authors.initials: T
authors.lastname: Kupper
mesh_terms: D002462:Cell Membrane / Q000473:pathology; D048429:Cell Size / Q000276:immunology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000378:metabolism*; D015603:Keratinocytes / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors*; D012501:Saphenous Vein; D012795:Sialoglycoproteins / Q000378:metabolism*; D013314:Stress, Mechanical
chemical_list: C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D017472:Receptors, Interleukin-1; D012795:Sialoglycoproteins