Release of soluble tryptase but only minor amounts of chymase activity from cutaneous mast cells

Abstract

Tryptase and chymase are the major serine proteinases of skin mast cells but their biologic significance depends on their activity. In this study, we demonstrate the release of soluble activity of tryptase, but not markedly that of chymase, into skin blister fluids induced by freezing with liquid nitrogen as well as into supernatant during incubation of 8 whole skin specimens with compound 48/80 for up to 2 days followed by sonication. Incubation of 3 other skin specimens in compound 48/80 for up to 2 days revealed that the number of mast cells displaying tryptase activity decreased significantly on day 2, and the number of mast cells showing chymase activity (but not those showing chymase immunoreactivity) decreased significantly on day 1 but not thereafter on day 2. The results of 3 skin organ cultures for up to 14 days showed steady decrease in the number of tryptase-positive cells but persistence of mast cells containing chymase activity. Chymase in solution was sensitively inhibited by 0.01 mg/ml alpha1-antichymotrypsin but higher concentrations (0.3-3.0 mg/ml) were needed for inhibiting chymase on skin sections. In conclusion, after mast cell degranulation tryptase activity is substantially solubilized and it may potentially affect both local and distant skin structures. Instead, chymase is partially inactivated and the remaining chymase activity persists at the site of degranulation having only local effects.

Is there a role for mast cells in psoriasis?

“…Furthermore, the subcellular localization of chymase diVers from that of tryptase within the secretory granules-chymase and cathepsin G are preferentially localized in more electron-dense amorphous granule subregions whereas tryptase resides in less electron-dense crystalline subregions [205]. These diVerences may explain the Wndings that tryptase protein diVuses away together with histamine whereas chymase protein tends to remain at the site of mast cells in human skin biopsies cultured and activated ex vivo [95,96]. Thus, tryptase can diVuse through the extracellular matrix and reach more distant target sites in the skin whereas chymase functions rather locally.…”

“…Thus, the activity of chymase is controlled by protease inhibitors normally present in inXamed tissue whereas tryptase may have a prolonged action time after being released from mast cells. In support for this, inactivation of chymase has been shown to take place rapidly in the skin, e.g., in the allergic skin wheal reaction [155], cutaneous herpes zoster lesions [86] and skin organ cultures [95,96], as detected enzyme-and immunohistochemically.…”

The production of collagen and the activity of mast‐cell chymase increase in human skin after irradiation therapy

“…For the staining of mast‐cell tryptase and chymase, 5‐µm cryosections were fixed in 0.6% formaldehyde and 0.5% acetic acid (pH adjusted to 7.2) for 10 min. Tryptase activity was demonstrated enzyme‐histochemically with 1 mM Z‐Gly‐Pro‐Arg‐MNA as the substrate and 0.5 mg/ml Fast black K salt as the chromogen (pH 7.5), as described previously (24,25). Chymase activity was demonstrated enzyme‐histochemically with 1 mM Suc‐Val‐Pro‐Phe‐MNA and 0.5 mg/ml Fast black K salt (24,25).…”

Heparin modulates the growth and adherence and augments the growth‐inhibitory action of TNF‐α on cultured human keratinocytes

“…Also, heparin efficiently binds mast cell tryptase and chymase which can degrade the basement membrane and induce dermal-epidermal separation [Briggaman et al, 1984;Kaminska et al, 1999a,b]. Soluble tryptase-heparin proteoglycan complexes are likely to reach epidermal keratinocytes after being released from mast cells [Kivinen et al, 2001]. Furthermore, heparin and other proteoglycans can bind cytokines and growth factors, such as basic fibroblast growth factor, amphiregulin, and keratinocyte growth factor, and thereby modify their growth inducing effects on keratinocytes and epithelial cells [Shipley et al, 1989;Ruoslahti and Yamaguchi, 1991;Piepkorn et al, 1994;Putnins et al, 1996;Schönherr and Hausser, 2000].…”