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Research article2012Peer reviewedOpen access

Mast cells limit extracellular levels of IL-13 via a serglycin proteoglycan-serine protease axis

Waern, Ida; Karlsson, Iulia; Schlenner, SM; Feyerabend, TB; Rodewald, HR; Åbrink, Magnus; Hellman, L; Pejler, Gunnar; Wernersson, Sara

Abstract

Mast cell (MC) granules contain large amounts of proteases of the chymase, tryptase and carboxypeptidase A (MC-CPA) type that are stored in complex with serglycin, a proteoglycan with heparin side chains. Hence, serglycin-protease complexes are released upon MC degranulation and may influence local inflammation. Here we explored the possibility that a serglycin-protease axis may regulate levels of IL-13, a cytokine involved in allergic asthma. Indeed, we found that wild-type MCs efficiently degraded exogenous or endogenously produced IL-13 upon degranulation, whereas serglycin(-/-) MCs completely lacked this ability. Moreover, MC-mediated IL-13 degradation was blocked both by a serine protease inhibitor and by a heparin antagonist, which suggests that IL-13 degradation is catalyzed by serglycin-dependent serine proteases and that optimal IL-13 degradation is dependent on both the serglycin and the protease component of the serglycin-protease complex. Moreover, IL-13 degradation was abrogated in MC-CPA(-/-) MC cultures, but was normal in cultures of MCs with an inactivating mutation of MC-CPA, which suggests that the IL-13-degrading serine proteases rely on MC-CPA protein. Together, our data implicate a serglycin-serine protease axis in the regulation of extracellular levels of IL-13. Reduction of IL-13 levels through this mechanism possibly can provide a protective function in the context of allergic inflammation.

Keywords

allergy; cytokine; mast cell; proteoglycan; serine protease

Published in

Biological Chemistry
2012, Volume: 393, number: 12, pages: 1555-1567
Publisher: WALTER DE GRUYTER & CO GENTHINER STRASSE 13, D-10785 BERLIN, GERMANY