α<sub>1</sub>-Antitrypsin Inhibits the Activity of the Matriptase Catalytic Domain <i>In Vitro</i>

Janciauskiene, Sabina; Nita, Gelu M.; Subramaniyam, Devipriya; Li, Qian; Lancaster, Jack R.; Matalon, Sadis

doi:10.1165/rcmb.2008-0015rc

Cited by 36 publications

(27 citation statements)

References 38 publications

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“…In support of this hypothesis, recently, Tseng and colleagues (44) isolated A1AT/matriptase complexes from human milk that are resistant to dissociation in boiling SDS, suggesting that A1AT may bind to matriptase in an irreversible fashion. We also reported that native but not the inactivated A1AT inhibits the catalytic domain of matriptase with a second-order rate constant of 0.31 3 10 3 M 21 s 21 in vitro in an irreversible fashion (16). Other serine proteinase inhibitors, like aprotinin and nexin-1 (PN-1) have also been shown to inhibit the activity of matriptase, thereby decreasing ENaC currents.…”

Section: Discussionmentioning

confidence: 87%

α₁-Antitrypsin Inhibits Epithelial Na⁺ Transport In Vitro and In Vivo

Lazrak¹,

Nita²,

Subramaniyam³

et al. 2009

Am J Respir Cell Mol Biol

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A variety of studies have shown that Na 1 reabsorption across epithelial cells depends on the protease-antiprotease balance. Herein, we investigate the mechanisms by which a 1 -antitrypsin (A1AT), a major anti-serine protease in human plasma and lung epithelial fluid and lacking a Kunitz domain, regulates amiloridesensitive epithelial Na 1 channel (ENaC) function in vitro and in vivo. A1AT (0.05 mg/ml 5 1 mM) decreased ENaC currents across Xenopus laevis oocytes injected with human a,b,g-ENaC (hENaC) cRNAs, and human lung Clara-like (H441) cells expressing native ENaC, in a partially irreversible fashion. A1AT also decreased ENaC singlechannel activity when added in the pipette but not in the bath solutions of ENaC-expressing oocytes patched in the cell-attached mode. Incubation of A1AT with peroxynitrite (ONOO 2 ), an oxidizing and nitrating agent, abolished its antiprotease activity and significantly decreased its ability to inhibit ENaC. Intratracheal instillation of normal but not ONOO 2 -treated A1AT (1 mM) in C57BL/6 mice also decreased Na 1 -dependent alveolar fluid clearance to the same level as amiloride. Incubation of either H441 cells or ENaC-expressing oocytes with normal but not ONOO 2 -treated A1AT decreased their ability to cleave a substrate of serine proteases. A1AT had no effect on amiloride-sensitive currents of oocytes injected with hENaC bearing Liddle mutations, presumably because these channels remain at the surface longer than the wild-type channels. These data indicate that A1AT may be an important modulator of ENaC activity and of Na 1 -dependent fluid clearance across the distal lung epithelium in vivo by decreasing endogenous protease activity needed to activate silent ENaC.Keywords: alveolar fluid clearance; serine proteases; H441 cells; Xenopus oocytes; ENaCThe amiloride-sensitive epithelial Na 1 channels (ENaCs) play an important role in Na 1 and fluid homeostasis across a number of epithelial cells, including those in airway and alveolar spaces (1, 2). ENaC mRNA, protein levels, and ENaC activity are regulated by a variety of hormones (such as aldosterone and dexamethasone), second messengers cAMP/protein kinase A, and reactive intermediates (2-4). In addition, endogenous channelactivating proteases (CAPs), as well as proteases released by inflammatory cells (trypsin, elastase), activate ENaC either by cleaving critical amino acids in a-and g-ENaC subunits, or by activating signaling pathways (1, 2, 5-7).There has been considerable interest in identifying the mechanisms by which endogenous and exogenous proteases activate ENaC. Aprotinin, a potent and reversible Kunitz-type inhibitor of several serine proteases, including trypsin, plasmin, and kallikreins (8), has been reported to inhibit sodium transport among a variety of epithelial cells, including A6 (9), human bronchial epithelial (HBE) cells (10, 11), and rat and mouse lung alveolar epithelial cells (1). Other Kunitz-type serine protease inhibitors, such as hepatocyte growth factor activator inhibitor (HAI)-1 and HAI-2 (plac...

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Section: Discussionmentioning

confidence: 87%

α₁-Antitrypsin Inhibits Epithelial Na⁺ Transport In Vitro and In Vivo

Lazrak¹,

Nita²,

Subramaniyam³

et al. 2009

Am J Respir Cell Mol Biol

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“…Indeed, the absence of elastase had no effect on neutrophil recruitment (26), which supports our findings. Circulating AAT enters cells (27) and can act as an inhibitor for matriptase (28), caspases-1 and -3 (29,30), TNF-α-converting enzyme (31), and intracellular calpain I (32).…”

Section: Discussionmentioning

confidence: 99%

Anti-inflammatory and immunomodulatory properties of α1-antitrypsin without inhibition of elastase

Jonigk

Al-Omari²,

Maegel

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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The rationale of α1-antitrypsin (AAT) augmentation therapy to treat progressive emphysema in AAT-deficient patients is based on inhibition of neutrophil elastase; however, the benefit of this treatment remains unclear. Here we show that clinical grade AAT (with elastase inhibitory activity) and a recombinant form of AAT (rAAT) without anti-elastase activity reduces lung inflammatory responses to LPS in elastase-deficient mice. WT and elastasedeficient mice treated with either native AAT or rAAT exhibited significant reductions in infiltrating neutrophils (23% and 68%), lavage fluid levels of TNF-α (70% and 80%), and the neutrophil chemokine KC (CXCL1) (64% and 90%), respectively. Lung parenchyma TNF-α, DNA damage-inducible transcript 3 and X-box binding protein-1 mRNA levels were reduced in both mouse strains treated with AAT; significantly lower levels of these genes, as well as IL-1β gene expression, were observed in lungs of AAT-deficient patients treated with AAT therapy compared with untreated patients. In vitro, LPS-induced cytokines from WT and elastasedeficient mouse neutrophils, as well as neutrophils of healthy humans, were similarly reduced by AAT or rAAT; human neutrophils adhering to endothelial cells were decreased by 60-80% (P < 0.001) with either AAT or rAAT. In mouse pancreatic islet macrophages, LPS-induced surface expression of MHC II, Toll-like receptor-2 and -4 were markedly lower (80%, P < 0.001) when exposed to either AAT or rAAT. Consistently, in vivo and in vitro, rAAT reduced inflammatory responses at concentrations 40-to 100-fold lower than native plasma-derived AAT. These data provide evidence that the anti-inflammatory and immunomodulatory properties of AAT can be independent of elastase inhibition.is the prototypic member of the serpin superfamily and one of the most abundant serine protease inhibitors in the circulation (1). As an acute-phase protein, AAT is thought to play an important role in limiting host-tissue injury triggered by proteases, particularly neutrophil elastase (NE). The clinical relevance of AAT is highlighted in individuals with inherited deficiency in circulating AAT, who have increased susceptibility to early-onset pulmonary emphysema, liver and pancreatic diseases, and in rare cases to panniculitis and vasculitis (2). It has been assumed that in AAT-deficiency the protease/antiprotease balance is shifted toward NE, which leads to extensive tissue damage, particularly in causing emphysema. Therefore, augmentation of circulating AAT was introduced 25 y ago to treat emphysema patients with severe PiZZ (Glu342Lys) AAT deficiency (3). Because clinical trials of AAT augmentation therapy use historical data as controls, the benefit of AAT therapy for PiZZ patients remains under debate (4-6), although in most cases therapy offers disease stabilization. The uncertainty surrounding the efficacy of augmentation therapy also reflects the incomplete understanding of the properties of the AAT protein, which can be affected by the isolation methods from plasma.Although the a...

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“…Protease inhibitor nexin 1, another member of the SERPIN family that inhibits matriptase (52,53), also inhibited Na 1 currents across human airway epithelial cells isolated from CF lungs (52). Based on Western blotting studies of surface proteins of ATII cells in culture and in situ, we conclude that IaI decreased ENaC activity by preventing membran-bound proteases from cleaving portions of the extracellular loops of a-and g-ENaC subunits, thereby inhibiting the activation of ENaC at the cell membrane of lung epithelial cells and oocytes.…”

Section: Original Researchmentioning

confidence: 99%

Inter-α-Inhibitor Blocks Epithelial Sodium Channel Activation and Decreases Nasal Potential Differences in ΔF508 Mice

Lazrak

Jurkuvenaite

Ness

et al. 2014

Am J Respir Cell Mol Biol

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Increased activity of lung epithelial sodium channels (ENaCs) contributes to the pathophysiology of cystic fibrosis (CF) by increasing the rate of epithelial lining fluid reabsorption. Intera-inhibitor (IaI), a serum protease inhibitor, may decrease ENaC activity by preventing its cleavage by serine proteases. High concentrations of IaI were detected in the bronchoalveolar lavage fluid (BALF) of children with CF and lower airway diseases. IaI decreased amiloride-sensitive (I ENaC ) but not cAMP-activated Cl 2 currents across confluent monolayers of rat ATII, and mouse nasal epithelial cells grew in primary culture by 45 and 25%, respectively. Changes in I ENaC by IaI in ATII cells were accompanied by increased levels of uncleaved (immature) surface a-ENaC. IaI increased airway surface liquid depth overlying murine nasal epithelial cells to the same extent as amiloride, consistent with ENaC inhibition. Incubation of lung slices from C57BL/6, those lacking phenylalanine at position 508 (ΔF508), or CF transmembrane conductance regulator knockout mice with IaI for 3 hours decreased the open probability of their ENaC channels by 50%. ΔF508 mice had considerably higher levels the amiloride-sensitive fractions of ENaC nasal potential difference (ENaC-NPD) than wild-type littermates and only background levels of IaI in their BALF. A single intranasal instillation of IaI decreased their ENaC-NPD 24 hours later by 25%. In conclusion, we show that IaI is present in the BALF of children with CF, is an effective inhibitor of ENaC proteolysis, and decreases ENaC activity in lung epithelial cells of ΔF508 mice.

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α₁-Antitrypsin Inhibits the Activity of the Matriptase Catalytic Domain In Vitro

Cited by 36 publications

References 38 publications

α₁-Antitrypsin Inhibits Epithelial Na⁺ Transport In Vitro and In Vivo

α₁-Antitrypsin Inhibits Epithelial Na⁺ Transport In Vitro and In Vivo

Anti-inflammatory and immunomodulatory properties of α1-antitrypsin without inhibition of elastase

Inter-α-Inhibitor Blocks Epithelial Sodium Channel Activation and Decreases Nasal Potential Differences in ΔF508 Mice

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α1-Antitrypsin Inhibits the Activity of the Matriptase Catalytic Domain In Vitro

Cited by 36 publications

References 38 publications

α1-Antitrypsin Inhibits Epithelial Na+ Transport In Vitro and In Vivo

α1-Antitrypsin Inhibits Epithelial Na+ Transport In Vitro and In Vivo

Anti-inflammatory and immunomodulatory properties of α1-antitrypsin without inhibition of elastase

Inter-α-Inhibitor Blocks Epithelial Sodium Channel Activation and Decreases Nasal Potential Differences in ΔF508 Mice

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α₁-Antitrypsin Inhibits the Activity of the Matriptase Catalytic Domain In Vitro

α₁-Antitrypsin Inhibits Epithelial Na⁺ Transport In Vitro and In Vivo

α₁-Antitrypsin Inhibits Epithelial Na⁺ Transport In Vitro and In Vivo