title: Proteolytic activation of matrix metalloproteinase-9 in skin wound healing is inhibited by alpha-1-antichymotrypsin.
abstract: An excessive amount of matrix metalloproteinase-9 (MMP-9) has been well documented in inflammatory diseases, including chronic wounds and cancers. Secreted as a zymogen, proMMP-9 can be irreversibly converted to a mature form through cleavage of the N-terminal propeptide domain. Although the converting enzyme for proMMP-9 in human tissues is unknown, we previously found that tumor necrosis factor-alpha (TNF-alpha) promotes activation of proMMP-9 in human skin, and characterized the converting activities as tissue-associated chymotrypsin-like proteinases. On the other hand, the pathophysiologic inhibitor to prevent proMMP-9 maturation also remains elusive. In this regard, we observed the presence of the inhibitory property in burn blister fluid that abrogates the skin extract-mediated activation of proMMP-9. Then we determined that alpha-1-antichymotrypsin (alpha-ACT), an acute-phase factor abundantly present in the blister, effectively inhibited proMMP-9 activation in human and rodent skin. In contrast, the aminophenylmercuric acetate-induced "cysteine switch" and activation of proMMP-9 were not affected by alpha-ACT. TNF-alpha-induced activation of proMMP-9 by the explants of human skin was inhibited by alpha-ACT but not by related alpha-1-antitrypsin. alpha-ACT specifically attenuated maturation of proMMP-9 but not proMMP-2 or proMMP-13. Furthermore, short peptides that mimic the reactive center loop (RCL) of alpha-ACT were sufficient to inhibit the conversion. Mutation analysis demonstrated that a conserved leucine within the RCL was critical for alpha-ACT-exerted inhibition. In chronic wounds, a large amount of mature MMP-9 was associated with fragmentation and inactivation of alpha-ACT. Taken together, these results demonstrate that, to the best of our knowledge, alpha-ACT is a previously unreported pathophysiologic inhibitor that controls proMMP-9 activation in skin tissue.
authors.affiliation: Division of Plastic and Reconstructive Surgery, Department of Surgery, The Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA. yhan@surgery.usc.edu
authors.forename: Yuan-Ping
authors.initials: YP
authors.lastname: Han
authors.forename: Chunli
authors.initials: C
authors.lastname: Yan
authors.forename: Warren L
authors.initials: WL
authors.lastname: Garner
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001706:Biopsy; D001768:Blister / Q000378:metabolism; D056649:Cathepsin G; D002403:Cathepsins / Q000502:physiology; D002478:Cells, Cultured; D004792:Enzyme Precursors / Q000378:metabolism; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008969:Molecular Sequence Data; D051381:Rats; D012697:Serine Endopeptidases / Q000502:physiology; D012867:Skin / Q000378:metabolism* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology*; D000514:alpha 1-Antichymotrypsin / Q000032:analysis / Q000502:physiology*; D000515:alpha 1-Antitrypsin / Q000502:physiology
chemical_list: D004792:Enzyme Precursors; C043392:SERPINA1 protein, human; D014409:Tumor Necrosis Factor-alpha; D000514:alpha 1-Antichymotrypsin; D000515:alpha 1-Antitrypsin; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; C534097:Ctsg protein, rat; C120487:pro-matrix metalloproteinase 9; D020780:Matrix Metalloproteinase 9