Differential gene expression of 3D primary human airway cultures exposed to cigarette smoke and electronic nicotine delivery system (ENDS) preparations.

BACKGROUND: Acute exposure to cigarette smoke alters gene expression in several biological pathways such as apoptosis, immune response, tumorigenesis and stress response, among others. However, the effects of electronic nicotine delivery systems (ENDS) on early changes in gene expression is relatively unknown. The objective of this study was to evaluate the early toxicogenomic changes using a fully-differentiated primary normal human bronchial epithelial (NHBE) culture model after an acute exposure to cigarette and ENDS preparations. RESULTS: RNA sequencing and pathway enrichment analysis identified time and dose dependent changes in gene expression and several canonical pathways when exposed to cigarette preparations compared to vehicle control, including oxidative stress, xenobiotic metabolism, SPINK1 general cancer pathways and mucociliary clearance. No changes were observed with ENDS preparations containing up to 28 µg/mL nicotine. Full model hierarchical clustering revealed that ENDS preparations were similar to vehicle control. CONCLUSION: This study revealed that while an acute exposure to cigarette preparations significantly and differentially regulated many genes and canonical pathways, ENDS preparations containing the same concentration of nicotine had very little effect on gene expression in fully-differentiated primary NHBE cultures.

Identification and characterization of receptors specific for human pancreatic secretory trypsin inhibitor.

Specific binding sites for human pancreatic secretory trypsin inhibitor (PSTI) on 3T3 Swiss albino cells were studied using radioiodinated recombinant PSTI. Some ion species, pH, and temperature significantly influenced the binding of 125I-PSTI. Kinetic studies showed that the binding of 125I-PSTI to 3T3 Swiss albino cells reached the maximum level within 120 min at 4 degrees C, with a slow dissociation rate. The half-maximal inhibition (ID50) of 125I-PSTI binding by unlabeled PSTI occurred at 1.0 x 10(-10) M. On Scatchard analysis of the competitive binding data, linear plots indicated a single class of receptors with high affinity (Kd = 5.3 x 10(-10) M) on 3T3 Swiss albino cells, the number of receptors being 5,400 per cell. Treatment of surface-bound radiolabeled PSTI with a chemical crosslinker (disuccinimidyl suberate) led to the identification of a membrane polypeptide of Mr 140,000 to which PSTI was crosslinked. The formation was inhibited by an excess amount of unlabeled PSTI in a dose-dependent manner. The binding of 125I-PSTI to 3T3 Swiss albino cells was competitively inhibited by unlabeled PSTI but not by other peptide hormones, such as epidermal growth factor (EGF), bovine fibroblast growth factor, insulin-like growth factor, transforming growth factor alpha, platelet-derived growth factor, and tumor necrosis factor, indicating the presence of receptors specific for PSTI. Various protease inhibitors had no or only a little effect, and mercaptoethanol and dithiothreitol strongly decreased the binding of 125I-PSTI. Incubation at 37 degrees C resulted in rapid internalization of cell-bound 125I-PSTI, followed by the appearance of trichloroacetic acid-soluble 125I-radioactivity in the culture medium, due to degradation of internalized PSTI. In addition, PSTI stimulated [3H]thymidine incorporation into DNA on 3T3 Swiss albino cells in a dose-dependent manner. The combined addition of PSTI and EGF stimulated [3H]thymidine incorporation to an extent greater than that seen with either agent alone. These results indicated that the biological effect of PSTI was mediated by high affinity plasma membrane receptors, which were not a cell-surface proteinase(s). Specific binding of 125I-PSTI was noted with the following cells: WI-38, 3T3 Swiss albino, HUVE, BDC-1, and H4-II-E-C3.

Pancreatic secretory trypsin inhibitor reduces multi-organ injury caused by gut ischemia/reperfusion in mice.

Intestinal ischemia/reperfusion (I/R) injury occurs during transplantation, mesenteric arterial occlusion, trauma and shock, causing systemic inflammation, multiple organ dysfunction and high mortality. Pancreatic secretory trypsin inhibitor (PSTI), a serine protease inhibitor expressed in gut mucosa may function as a mucosal protective/repair peptide. We examined whether PSTI affected mesenteric I/R-induced injury. Hypoxia/normoxia (H/N) caused 50% drop in cell viability of AGS, RIE1 and Caco-2 cells but PSTI (10 µg/ml) given prior- or during-hypoxic period improved survival by 50% (p<0.01). Similarly, Caco-2 monolayers exposed to H/N had 300% increase in transepithelial permeability, PSTI truncated this by 50% (p<0.01). Mice underwent mesenteric I/R by clamping jejunum, causing severe mucosal injury, increased apoptotic markers and 3-fold increases in plasma IL-6, IL1ß, TNFα, and tissue lipid peroxidation (MDA) and inflammatory infiltration (MPO) levels. Lungs showed similar significant injury and inflammatory infiltrate markers. Smaller increases in MDA and MPO were seen in kidney & liver. PSTI (20 mg/kg) reduced all injury markers by 50-80% (p<0.01). In vitro and in vivo studies showed PSTI reduced pro-apoptotic Caspase 3, 9 and Baxα levels, normalised Bcl2 and caused additional increases in HIF1α, VEGF and Hsp70 above rises caused by I/R alone (all p<0.01). PSTI also prevented reduction of tight junction molecules ZO1 and Claudin1 (all p<0.01) but did not affect increased ICAM-1 caused by I/R in gut or lung. PSTI may be a useful clinical target to prevent I/R injury.

Trypsin activation. Effect of the Ile-Val dipeptide concentration on Kazal inhibitor binding to bovine trypsinogen.

The effect of Ile-Val concentration (up to 2.0 M) on the thermodynamic parameters for the binding of the porcine pancreatic secretory trypsin inhibitor (Kazal inhibitor) to trypsinogen has been investigated at pH 5.5 between 7 degrees C and 42 degrees C. Thermodynamic parameters for Kazal inhibitor binding to the Ile-Val:zymogen adduct are more favorable than those observed for inhibitor association to the free proenzyme, but less so than those reported for beta-trypsin:Kazal inhibitor adduct formation (even under saturating dipeptide concentrations), suggesting that the effector dipeptide does not induce a complete rigidification of the proenzyme's activation domain. Considering the dependence of the association equilibrium constant for Kazal inhibitor binding to trypsinogen from Ile-Val concentration, thermodynamic parameters for the effector dipeptide binding to the free proenzyme and to its binary complex with Kazal inhibitor have been obtained. Differences in affinity for Ile-Val binding to the free zymogen and its binary complexes with inhibitors and substrates are indicative of the presence of different activation levels of the proenzyme, none of them exactly coincident with that of beta-trypsin. Such different discrete states should correspond to those involved in the zymogen-to-active-enzyme transition which should not be considered as an all-or-nothing process, but as a multistep event.

Plasminogen activator from human embryonic kidney cell cultures. Evidence for a proactivator.

The nature of the trypsin-activatable plasminogen activator produced by kidney cell cultures (Bernik, M.B (1973), J. Clin. Invest. 52, 823-834) was investigated using human embryonic kidney (HEK) cell cultures in serum-free medium. Plaminogen activator activity ratios (trypsin-activated/ untreated controls) in HEK cell-conditioned media were maximal (up to 3) during the first week of culture and remained nearly constant at approximatley 2 for the next 3-5 weeks, while the total plasminogen activator titer increased in a nearly linear manner. Therefore, coincident with progressive cell degeneration and death, the ratios decreased to near unity due to "spontaneous" activation of the enzyme, which was inhibited in cell-free conditioned media by the pancreatic trypsin inhibitor Kunitz and benzamidine. Since the activator is not inhibited by the trypsin inhibitor, it is concluded that a protease other than the plasminogen activator is responsible for the activation. Increases in the plasminogen activator titers (about 2-fold) were similarly obtained by culturing the cells in medium containing low concentrations (0.05-0.10 mug/ml) of trypsin for up to about 6 weeks. The presence of the trypsin inhibitor in HEK cells cultures decreased the rate of activation, resulting in higher activity ratios (up to 6), and the total plasminogen activator activity was reduced only minimally (less than 20%), if at all, by the highest concentration of the trypsin inhibitor (100 mug/ml) tested. Affinity chromatography of conditioned media with activity ratios of 1.6--2 separated the plasminogen activator into an active fraction and a fraction which was activated a minimum of 200-fold by trypsin and contained no measurable activity prior to activation. Gel filtration of crude conditioned media or partially purified activator separated the plasminogen activator into two peaks; both were trypsin-activatable, and their relative proportions varied with the isolated conditions. The results indicate the occurrence of a proenzyme form of the plasminogen activator in the culture media.

Purification and characterization of a novel Kazal-type serine proteinase inhibitor of neutrophil elastase from sheep lung.

A Kazal-type elastase inhibitor was purified by trichloroacetic acid precipitation of sheep lung lavage fluid followed by chymotrypsin affinity and gel-filtration chromatography of the supernatant. Sheep lung elastase inhibitor (SLEI) is glycosylated. Laser desorption mass spectrometry indicated that SLEI has a molecular mass of 16.8-17.3 kDa. Partial protein sequence of SLEI and of a peptide derived from SLEI showed 31-52% and 51-66% homology at the N-terminus and at the inhibitory site respectively with Kazal-type double-headed proteinase inhibitors (bikazins). SLEI inhibited human leukocyte elastase and porcine pancreatic elastase but not human cathepsin G. It was inactivated by chloramine-T and reactivated when incubated with methionine sulfoxide peptide reductase and dithiothreitol, indicating the presence of a methionine at the active site. The concentration of SLEI in bronchoalveolar lavage fluid (BALF) and lung lymph was 0.28 microM (0.23-0.49); 0.24 microM (0.20-0.31) (median, (range), n = 5), respectively and was undetectable in plasma (< 0.03 microM) suggesting that SLEI is produced in the lung. The median molar ratios of SLEI to alpha1-proteinase inhibitor in BALF and lung lymph were 3.2 to 1 and 0.017 to 1, respectively. These results indicate that SLEI probably makes an important contribution to antielastase defence in epithelial lining liquid.

Human pancreatic secretory trypsin inhibitor (PSTI) produced in active form and secreted from Escherichia coli.

As a basis for a protein design project, we decided to produce the human pancreatic secretory trypsin inhibitor (PSTI) in its active form. Total gene synthesis was carried out efficiently by (i) computer design of the gene fragments, (ii) synthesis of the oligodeoxynucleotides by the segmental support method, and (iii) assembly of double strands under optimized ligation conditions. Fusion to the ompA gene signal peptide led to secretion of processed PSTI in various constructions, with or without additional amino acids (aa) at the N-terminus. The secreted proteins (56 to 63 aa) were biologically active, suggesting that the three cysteine bridges were correctly formed. Surprisingly, after induction the product was found almost exclusively in the culture medium. Variants of PSTI with Asp or Asn at aa positions 21 and 29 [sequences published by Greene et al., Methods Enzymol. (1976) 813-825, and by Yamamoto et al., Biochem. Biophys. Res. Commun. (1985) 605-612] showed the same Ki for both human and porcine trypsin.

Purification and complete amino acid sequence of canine pancreatic secretory trypsin inhibitor.

Pancreatic secretory trypsin inhibitor (PSTI) was purified from canine pancreatic juice by HPLC. Canine PSTI inhibited bovine trypsin activity stoichiometrically and strongly with a dissociation constant of below 10(-9) M. The amino acid sequence of canine PSTI was determined by conventional methods. It had one more amino acid residue at the amino-terminus than other mammalian PSTIs, i.e. human, porcine, bovine and ovine.

Pancreatic secretory trypsin inhibitor (PSTI) isolated from pig intestine. Influence on insulin and somatostatin release.

Upon investigation of pig intestinal peptides for effects on the release of endocrine hormones from the isolated perfused rat pancreas, we reported earlier that glucose-stimulated insulin release was inhibited by PEC-60, a peptide with marked sequence similarity to PSTI (pancreatic secretory trypsin inhibitor). Continuing this study we found a polypeptide, which inhibited glucose-induced insulin release but enhanced glucose-induced somatostatin secretion. Determination of the amino acid sequence of this polypeptide revealed that it is identical to that of PSTI. Thus, PSTI modulates islet hormone release.

RBI, a one-domain alpha-amylase/trypsin inhibitor with completely independent binding sites.

The bifunctional inhibitor from Ragi (Eleusine coracana Gaertneri) (RBI) is the only member of the alpha-amylase/trypsin inhibitor family that inhibits both trypsin and alpha-amylase. Here, we show that both enzymes simultaneously and independently bind to RBI. The recently solved three-dimensional NMR structure of RBI has revealed that the inhibitor possesses a hitherto unknown fold for serine proteinase and alpha-amylase inhibitors. Despite its different fold, RBI obeys the standard mechanism observed for most protein inhibitors of serine proteinases and is a strong, competitive inhibitor of bovine trypsin (Ki = 1.2 +/- 0.2 nM). RBI is also a competitive inhibitor of porcine alpha-amylase (Ki = 11 +/- 2 nM) when a disaccharide is used as a substrate of alpha-amylase. However, the inhibition mode becomes complex when larger (> or = 7 saccharide units) alpha-amylase substrates are used. A second saccharide binding site on porcine alpha-amylase may enable larger oligosaccharides to displace RBI from its binding site in an intramolecular reaction.

Inhibition spectra of the human pancreatic endopeptidases.

The present work describes the effect of seven naturally occurring proteinase inhibitors on the human pancreatic endopeptidases cationic trypsin, anionic trypsin, chymotrypsin I, chymotrypsin II, and protease E (an elastase-like protease). The inhibitors tested in order of their decreasing effectiveness were alpha-1-proteinase inhibitor (alpha-1-antitrypsin), lima bean trypsin inhibitor, soybean trypsin inhibitor, Bowman-Birk (soybean) inhibitor, Kunitz pancreatic trypsin inhibitor, porcine Kazal inhibitor, and chicken ovomucoid. The human trypsins demonstrated a higher degree of susceptibility to these inhibitors than did the chymotrypsins while human protease E showed remarkably little inhibition by any of these naturally occurring proteinase inhibitors except for alpha-1-proteinase inhibitor. The contribution of each of these proteolytic enzymes to the total proteolytic activity of crude extracts was also investigated using specific active-site directed reagents. These studies revealed that the trypsins constituted approximately 35% of the proteolytic activity while the chymotrypsins represent approximately 32% of the total proteolytic activity. Human protease E and possibly human pancreatic elastase are responsible for approximately 21% of this activity as measured on crude pancreatic extracts.

The multiplicity of human pancreatic secretory trypsin inhibitor.

Four forms of pancreatic secretory trypsin inhibitor (PSTI; A1, A2, B, and C) were purified from human pancreatic juice. According to sequence results, the primary structure of B was different from that reported earlier (Greene, L.J., et al. (1976) Method Enzymol. 45, 813-825) at two positions, i.e. Asn21----Asp21, Asp29----Asn29. A1 and A2 were deamidated forms of B judging from peptide mappings with Staphylococcus aureus V8 protease. Gln45 in B was replaced by Glu in A1 and Gln51 in B was replaced by Glu in A2. C was an inhibitor lacking five amino acid residues from the amino terminal of B. B and C inhibited human cationic trypsin activity stoichiometrically with similar dissociation constants, but A1 and A2 showed poorer trypsin inhibitory activity than B and C.

Stimulatory effect of synthetic luminal cholecystokinin releasing factor (LCRF) fragment (1-35) on pancreatic exocrine secretion in conscious rats.

The effects of a synthetic putative luminal cholecystokinin (CCK) releasing factor (LCRF) fragment (1-35) on pancreatic exocrine secretion were examined in conscious Wistar rats and a mutant strain of rats lacking the CCK-A receptor. Intraduodenal injection of graded doses of the LCRF fragment induced biphasic responses in Wistar rats. The injection of 0.1 microgram of the LCRF fragment produced a maximal response, while 1 microgram produced a lower response. No significant effect was observed in rats lacking the CCK-A receptor. The synthetic LCRF fragment stimulated pancreatic secretion via CCK-A receptors in conscious rats.

CCK-releasing activity of rat intestinal secretion: effect of atropine and comparison with monitor peptide.

A bioassay for studying the cholecystokinin (CCK)-releasing activity of intraluminal protease-sensitive bioactive peptides was developed. In conscious rats, bile and pancreatic juice were chronically diverted from the proximal intestine to the ileum to cause chronic stimulation of CCK release and pancreatic protein secretion. CCK-releasing activity of test substances was assayed during transient inhibition of CCK release by intraduodenal sodium taurocholate (78 mumols/h). Intestinal secretion as a source of the putative trypsin-sensitive intestinal CCK-releasing peptide was obtained by rapid intestinal perfusion of isolated Thiry-Vella fistulae of jejunum in conscious rats, collected with or without atropine pretreatment. Partially purified rat pancreatic secretory trypsin inhibitor (PSTI, or "monitor peptide") was compared with ovomucoid trypsin inhibitor (OMTI) and with concentrated jejunal secretions for CCK-releasing activity and trypsin inhibitor activity. Concentrated, heat-treated jejunal secretions were the strongest stimulants of CCK release and pancreatic protein secretion in this model. OMTI had no CCK-releasing activity in this model, whereas a larger amount (approximately 5x, based on trypsin inhibitor activity) of PSTI weakly but significantly stimulated CCK release. CCK-releasing activity manifested by pancreatic protein secretion was equivalent in intestinal washes from atropine-treated and control Thiry-Vella fistula donor rats. Concentrated jejunal secretions had no trypsin inhibitory activity, indicating that the putative intestinal CCK-releasing peptide and "monitor peptide" are different substances.

Stimulatory effect of monitor peptide and human pancreatic secretory trypsin inhibitor on pancreatic secretion and cholecystokinin release in conscious rats.

The stimulatory effects of monitor peptide (MP) that was recently purified from rat bile-pancreatic juice on cholecystokinin (CCK) release and pancreatic exocrine secretions were examined in the conscious rat. As the sequence of MP has some homology with human pancreatic secretory trypsin inhibitor (hPSTI), the effects of these two materials were compared with each other. Rats were prepared with external bile and pancreatic fistulae. Pancreatic juice diversion significantly increased pancreatic secretions, but the intraduodenal injection of MP (0.9 micrograms per rat) could further increase pancreatic secretions. The MP injection produced significantly higher plasma CCK concentrations than the injection of isotonic saline solution did. Trasylol was infused simultaneously with pancreatic juice diversion to completely eliminate residual luminal protease activities. The MP (0.9 micrograms per rat) still showed the stimulatory effect, but hPSTI did not show any stimulatory effect on pancreatic secretion. Plasma CCK concentrations produced by MP were significantly higher than those produced by hPSTI. It was concluded that MP has a strong species specificity and that MP could stimulate CCK release and pancreatic exocrine secretions, not only via inhibiting luminal protease activities but also probably with a direct effect.

Effect of taurocholate on CCK release and pancreatic secretion produced by two CCK-releasing peptides in conscious rats.

The role of luminal bile salts (taurocholate) in regulation of rat pancreatic secretion was examined by studies on the effects of luminal stimulants on the pancreas during infusion of various concentrations of taurocholate into the duodenum of conscious rats. Rats with external bile and pancreatic fistulae were used. For 24 h before the experiment, pancreatic juice was excluded from the intestine but bile was continuously returned to the duodenum. From the beginning of the experiment, 8-200 mM of taurocholate was infused at a rate of 1 ml/h instead of returning the bile. Pancreatic juice was collected for a 2-h period and then 2 micrograms of pancreatic secretory trypsin inhibitor-61 (PSTI-61) (= monitor peptide) or partially purified putative CCK-releasing peptide from rat intestine (intestinal CCK-RP) was injected into the duodenum (1 ml/min). Continuous infusion of taurocholate maintained a constant rate of pancreatic secretion, except at a concentration of 8 mM, which resulted in a slight increase in pancreatic secretion. Both PSTI-61 and intestinal CCK-RP significantly increased pancreatic secretions during infusion of 20 or 40 mM taurocholate, but had no significant effect during infusion of 80 or 200 mM taurocholate. Therefore, higher concentrations of taurocholate in the intestine prevented the stimulatory effects of luminal stimulants, probably by preventing the latter from reaching CCK cells.

Vasopressor effects of intracerebroventricular injections of PEC-60, a novel porcine 60-residue intestinal peptide, in the awake unrestrained male rat.

Intracerebroventricular injections (140-4300 pmol) of a 60-residue polypeptide (now designated PEC-60) isolated from pig intestine produced a dose-dependent increase (peak action 21% +/- 2; ED50 value of 1.7 nmol for the peak effect) in mean arterial blood pressure (MAP) in the awake, unrestrained male rat. The heart rate (HR) was significantly reduced with the highest doses used (1400 and 4300 pmol). The pancreatic secretory trypsin inhibitor (PSTI), with a high degree of sequence similarity to PEC-60, did not significantly change MAP and HR (4300 pmol). These results may indicate a biological role for the putative PEC-60-like peptide demonstrated within central catecholamine cardiovascular neurons.

MMP-9 activation by tumor trypsin-2 enhances in vivo invasion of human tongue carcinoma cells.

Various human cancer cells express tumor-associated trypsinogen-2 (TAT-2), which can efficiently activate matrix metalloproteinases (MMPs) in vitro. MMP-2 and MMP-9 are particularly associated with the invasive malignant potential of several tumors. To investigate the role of TAT-2 in tumor invasion, we overexpressed TAT-2 in two malignant human squamous cell carcinoma cell lines of tongue and in non-malignant human papilloma virus transformed gingival keratinocytes. The TAT-2 overexpression significantly increased the levels of active MMP-9 in the most malignant cell line. TAT-2-transfected cells intravasated (invaded blood vessels) up to 60% more efficiently than did the control cells in an in vivo chick embryo chorioallantoic membrane invasion model. This increased intravasation was almost completely abolished by a specific tumor-associated trypsin inhibitor (TATI). These results indicate that TAT-2 has a role in the invasive growth of tumors, either alone or in cascade with gelatinases, especially by generating active MMP-9.

Differences in stimulatory effects between rat pancreatic secretory trypsin inhibitor-61 and -56 on rat pancreas.

Two types of pancreatic secretory trypsin inhibitors (PSTIs) were recently purified from rat pancreatic juice. One consisted of 61 (PSTI-61) and the other of 56 (PSTI-56) amino acid residues. PSTI-61 has been reported to elicit cholecystokinin (CCK) release when injected into the duodenum. Since no information has been available about the action of PSTI-56 on CCK release, the two PSTIs were compared for their stimulatory effect on CCK release and pancreatic exocrine secretions in conscious rats after intraduodenal administration. Rats were prepared with bile and pancreatic fistulae and with two duodenal cannulae. Pancreatic juice was excluded from the duodenum for 48 h prior to the experiment because rat PSTIs were trypsin sensitive. PSTI-61 significantly stimulated pancreatic secretions and increased plasma CCK concentrations from 3.6 to 6.5 pM, whereas PSTI-56 had no effect on either CCK release or pancreatic secretions. It is suggested that the action as a regulator for CCK release and pancreatic secretions is possessed only by PSTI-61, but not by PSTI-56.

Inhibition of membrane-type serine protease 1/matriptase by natural and synthetic protease inhibitors.

Membrane-type serine protease 1 (MT-SP1), identical to matriptase, is a recently identified type II transmembrane serine protease. MT-SP1/matriptase is of considerable interest for the development, homeostasis, and cancer invasion and metastasis of epithelial tissues. The administration of inhibitors for MT-SP1/matriptase may be effective to suppress the development of tumors where the enzyme may be involved. In the present study, we produced a secreted form of recombinant MT-SP1/matriptase (ekMT-SP1s) that can be activated by enterokinase in vitro and investigated the inhibitory ability of various protease inhibitors toward the recombinant enzyme. The enterokinase-treated ekMT-SP1s (active ekMT-SP1s) cleaved various peptidyl-4-methylcoumaryl-7-amide (MCA) substrates with arginine (or lysine) residue at position P1, and the best substrate was t-butyloxycarbonyl (Boc)-Gln-Ala-Arg-MCA. The specificity for the synthetic and natural substrates of the active ekMT-SP1s was in good agreement with that of the natural enzyme. Endogenous protease inhibitors tested, except for antithrombin III, showed no or little inhibition on the cleavage of Boc-Gln-Ala-Arg-MCA by the active ekMT-SP1s. Aprotinin showed strong inhibitory activity toward the cleavage. Food-derived inhibitors, such as soybean trypsin inhibitor, Bowman-Birk inhibitor, and lima bean trypsin inhibitor inhibited it, while chicken ovomucoid did not. Synthetic inhibitors tested inhibited it, and among them, the inhibitory effect of FOY-305 was strongest. The present findings provide important information for the suppression of cancer invasion and metastasis for which MT-SP1/matriptase is responsible.