title: LAP degradation product reflects plasma kallikrein-dependent TGF-β activation in patients with hepatic fibrosis.
abstract: Byproducts of cytokine activation are sometimes useful as surrogate biomarkers for monitoring cytokine generation in patients. Transforming growth factor (TGF)-β plays a pivotal role in pathogenesis of hepatic fibrosis. TGF-β is produced as part of an inactive latent complex, in which the cytokine is trapped by its propeptide, the latency-associated protein (LAP). Therefore, to exert its biological activity, TGF-β must be released from the latent complex. Several proteases activate latent TGF-β by cutting LAP. We previously reported that Camostat Mesilate, a broad spectrum protease inhibitor, which is especially potent at inhibiting plasma kallikrein (PLK), prevented liver fibrosis in the porcine serum-induced liver fibrosis model in rats. We suggested that PLK may work as an activator of latent TGF-β during the pathogenesis of liver diseases in the animal models. However, it remained to be elucidated whether this activation mechanism also functions in fibrotic liver in patients. Here, we report that PLK cleaves LAP between R(58) and L(59) residues. We have produced monoclonal antibodies against two degradation products of LAP (LAP-DP) by PLK, and we have used these specific antibodies to immunostain LAP-DP in liver tissues from both fibrotic animals and patients. The N-terminal side LAP-DP ending at R(58) (R(58) LAP-DP) was detected in liver tissues, while the C-terminal side LAP-DP beginning at L(59) (L(59) LAP-DP) was not detectable. The R(58) LAP-DP was seen mostly in α-smooth muscle actin-positive activated stellate cells. These data suggest for the first time that the occurrence of a PLK-dependent TGF-β activation reaction in patients and indicates that the LAP-DP may be useful as a surrogate marker reflecting PLK-dependent TGF-β activation in fibrotic liver both in animal models and in patients.
authors.affiliation: Micro-signaling Regulation Technology Unit, RIKEN Center for Life Science Technologies, 2-1 Hirosawa, Wako, Saitama, 351-0918 Japan.
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Hara
authors.affiliation: Micro-signaling Regulation Technology Unit, RIKEN Center for Life Science Technologies, 2-1 Hirosawa, Wako, Saitama, 351-0918 Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Kirita
authors.affiliation: Micro-signaling Regulation Technology Unit, RIKEN Center for Life Science Technologies, 2-1 Hirosawa, Wako, Saitama, 351-0918 Japan.
authors.forename: Wakako
authors.initials: W
authors.lastname: Kondo
authors.affiliation: Department of Laboratory Medicine, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-0003 Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Matsuura
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-0003 Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nagatsuma
authors.affiliation: Biomolecular Characterization Team, Chemical Biology Core Facility, Chemical Biology Department, RIKEN Advanced Science Institute, Wako, Saitama, 351-0918 Japan.
authors.forename: Naoshi
authors.initials: N
authors.lastname: Dohmae
authors.affiliation: St. Louis Laboratories, Pfizer Worldwide Research & Development, Chesterfield, MO 63166 U.S.A.
authors.forename: Shinji
authors.initials: S
authors.lastname: Ogawa
authors.affiliation: Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, 108-8639 Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Imajoh-Ohmi
authors.affiliation: Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, New York, NY 10029 U.S.A.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Friedman
authors.affiliation: Department of Cell Biology, New York University School of Medicine, New York, NY 10016 U.S.A.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Rifkin
authors.affiliation: Micro-signaling Regulation Technology Unit, RIKEN Center for Life Science Technologies, 2-1 Hirosawa, Wako, Saitama, 351-0918 Japan.
authors.forename: Soichi
authors.initials: S
authors.lastname: Kojima
keywords: Biomarker; Hepatic stellate cells; Liver fibrosis; Plasma kallikrein (PLK); TGF-β activation