Identification of Human Cathepsin G As a Functional Target of Boswellic Acids from the Anti-Inflammatory Remedy Frankincense
ABSTRACT Frankincense preparations, used in folk medicine to cure inflammatory diseases, showed anti-inflammatory effectiveness in animal models and clinical trials. Boswellic acids (BAs) constitute major pharmacological principles of frankincense, but their targets and the underlying molecular modes of action are still unclear. Using a BA-affinity Sepharose matrix, a 26-kDa protein was selectively precipitated from human neutrophils and identified as the lysosomal protease cathepsin G (catG) by mass spectrometry (MALDI-TOF) and by immunological analysis. In rigid automated molecular docking experiments BAs tightly bound to the active center of catG, occupying the same part of the binding site as the synthetic catG inhibitor JNJ-10311795 (2-[3-[methyl[1-(2-naphthoyl)piperidin-4-yl]amino]carbonyl)-2-naphthyl]-1-(1-naphthyl)-2-oxoethylphosphonic acid). BAs potently suppressed the proteolytic activity of catG (IC(50) of approximately 600 nM) in a competitive and reversible manner. Related serine proteases were significantly less sensitive against BAs (leukocyte elastase, chymotrypsin, proteinase-3) or not affected (tryptase, chymase). BAs inhibited chemoinvasion but not chemotaxis of challenged neutrophils, and they suppressed Ca(2+) mobilization in human platelets induced by isolated catG or by catG released from activated neutrophils. Finally, oral administration of defined frankincense extracts significantly reduced catG activities in human blood ex vivo vs placebo. In conclusion, we show that catG is a functional and pharmacologically relevant target of BAs, and interference with catG could explain some of the anti-inflammatory properties of frankincense.
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- "However, in vivo studies confirming the pharmacological relevance of these proposed target interactions are still missing, and the efficacy of defined BAs in in vivo models of inflammation remains to be assessed. Recently, we showed that the serine protease cathepsin G is a high affinity and pharmacologically relevant target of BAs (Tausch et al., 2009). Prostaglandins (PGs) are important lipid mediators derived from arachidonic acid (AA) that control not only numerous physiological events such as blood pressure, blood clotting and sleep, but also inflammation (Funk, 2001). "
ABSTRACT: Frankincense, the gum resin derived from Boswellia species, showed anti-inflammatory efficacy in animal models and in pilot clinical studies. Boswellic acids (BAs) are assumed to be responsible for these effects but their anti-inflammatory efficacy in vivo and their molecular modes of action are incompletely understood. A protein fishing approach using immobilized BA and surface plasmon resonance (SPR) spectroscopy were used to reveal microsomal prostaglandin E(2) synthase-1 (mPGES1) as a BA-interacting protein. Cell-free and cell-based assays were applied to confirm the functional interference of BAs with mPGES1. Carrageenan-induced mouse paw oedema and rat pleurisy models were utilized to demonstrate the efficacy of defined BAs in vivo. Human mPGES1 from A549 cells or in vitro-translated human enzyme selectively bound to BA affinity matrices and SPR spectroscopy confirmed these interactions. BAs reversibly suppressed the transformation of prostaglandin (PG)H(2) to PGE(2) mediated by mPGES1 (IC(50) = 3-10 µM). Also, in intact A549 cells, BAs selectively inhibited PGE(2) generation and, in human whole blood, β-BA reduced lipopolysaccharide-induced PGE(2) biosynthesis without affecting formation of the COX-derived metabolites 6-keto PGF(1α) and thromboxane B(2) . Intraperitoneal or oral administration of β-BA (1 mg·kg(-1) ) suppressed rat pleurisy, accompanied by impaired levels of PGE(2) and β-BA (1 mg·kg(-1) , given i.p.) also reduced mouse paw oedema, both induced by carrageenan. Suppression of PGE(2) formation by BAs via interference with mPGES1 contribute to the anti-inflammatory effectiveness of BAs and of frankincense, and may constitute a biochemical basis for their anti-inflammatory properties.British Journal of Pharmacology 01/2011; 162(1):147-62. DOI:10.1111/j.1476-5381.2010.01020.x
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ABSTRACT: Complementary therapies are frequently used by patients with inflammatory bowel disease (IBD). The aim of this study was to evaluate the efficacy and safety of long-term therapy with a new Boswellia serrata extract (Boswelan, PS0201Bo) in maintaining remission in patients with Crohn's disease (CD). In 22 German centers a double-blind, placebo-controlled, randomized, parallel study was performed. In all, 108 outpatients with CD in clinical remission were included. Patients were randomized to Boswelan (3×2 capsules/day; 400 mg each) or placebo for 52 weeks. The primary endpoint was the proportion of patients in whom remission was maintained throughout the 52 weeks. Secondary endpoints were time to relapse, changes of Crohn's Disease Activity Index (CDAI), and IBD Questionnaire (IBDQ) scores. The trial was prematurely terminated due to insufficient discrimination of drug and placebo with regard to the primary efficacy endpoint. A total of 82 patients were randomized to Boswelan (n=42) or placebo (n=40). Sixty-six patients could be analyzed for efficacy. 59.9% of the actively treated patients and 55.3% of the placebo group stayed in remission (P=0.85). The mean time to diagnosis of relapse was 171 days for the active group and 185 days for the placebo group (P=0.69). With respect to CDAI, IBDQ, and laboratory measurements of inflammation, no advantages in favor of active treatment were detected. Regarding safety concerns, no disadvantages of taking the drug compared to placebo were observed. The trial confirmed good tolerability of a new Boswellia serrata extract, Boswelan, in long-term treatment of CD. However, superiority versus placebo in maintenance therapy of remission could not be demonstrated.Inflammatory Bowel Diseases 08/2010; 17(2):573-82. DOI:10.1002/ibd.21345
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ABSTRACT: Cathepsin G is a major secreted serine peptidase of neutrophils and mast cells. Studies in Ctsg-null mice suggest that cathepsin G supports antimicrobial defenses but can injure host tissues. The human enzyme has an unusual "Janus-faced" ability to cleave peptides at basic (tryptic) as well as aromatic (chymotryptic) sites. Tryptic activity has been attributed to acidic Glu(226) in the primary specificity pocket and underlies proposed important functions, such as activation of prourokinase. However, most mammals, including mice, substitute Ala(226) for Glu(226), suggesting that human tryptic activity may be anomalous. To test this hypothesis, human cathepsin G was compared with mouse wild-type and humanized active site mutants, revealing that mouse primary specificity is markedly narrower than that of human cathepsin G, with much greater Tyr activity and selectivity and near absence of tryptic activity. It also differs from human in resisting tryptic peptidase inhibitors (e.g., aprotinin), while favoring angiotensin destruction at Tyr(4) over activation at Phe(8). Ala(226)Glu mutants of mouse cathepsin G acquire tryptic activity and human ability to activate prourokinase. Phylogenetic analysis reveals that the Ala(226)Glu missense mutation appearing in primates 31-43 million years ago represented an apparently unprecedented way to create tryptic activity in a serine peptidase. We propose that tryptic activity is not an attribute of ancestral mammalian cathepsin G, which was primarily chymotryptic, and that primate-selective broadening of specificity opposed the general trend of increased specialization by immune peptidases and allowed acquisition of new functions.The Journal of Immunology 10/2010; 185(9):5360-8. DOI:10.4049/jimmunol.1002292