Qingyi decoction attenuates intestinal epithelial cell injury via the calcineurin/nuclear factor of activated T-cells pathway.

BACKGROUND: Recent studies have demonstrated that dysfunction of the intestinal barrier is a significant contributing factor to the development of severe acute pancreatitis (SAP). A stable intestinal mucosa barrier functions as a major anatomic and functional barrier, owing to the balance between intestinal epithelial cell (IEC) proliferation and apoptosis. There is some evidence that calcium overload may trigger IEC apoptosis and that calcineurin (CaN)/nuclear factor of activated T-cells (NFAT) signaling might play an important role in calcium-mediated apoptosis. AIM: To investigate the potential mechanisms underlying the therapeutic effect of Qingyi decoction (QYD) in SAP. METHODS: A rat model of SAP was created via retrograde infusion of sodium deoxycholate. Serum levels of amylase, tumor necrosis factor (TNF-α), interleukin (IL)-6, D-lactic acid, and diamine oxidase (DAO); histological changes; and apoptosis of IECs were examined in rats with or without QYD treatment. The expression of the two subunits of CaN and NFAT in intestinal tissue was measured via quantitative real-time polymerase chain reaction and western blotting. For in vitro studies, Caco-2 cells were treated with lipopolysaccharide (LPS) and QYD serum, and then cell viability and intracellular calcium levels were detected. RESULTS: Retrograde infusion of sodium deoxycholate increased the severity of pancreatic and intestinal pathology and the levels of serum amylase, TNF-α, and IL-6. Both the indicators of intestinal mucosa damage (D-lactic acid and DAO) and the levels of IEC apoptosis were elevated in the SAP group. QYD treatment reduced the serum levels of amylase, TNF-α, IL-6, D-lactic acid, and DAO and attenuated the histological findings. IEC apoptosis associated with SAP was ameliorated under QYD treatment. In addition, the protein expression levels of the two subunits of CaN were remarkably elevated in the SAP group, and the NFATc3 gene was significantly upregulated at both the transcript and protein levels in the SAP group compared with the control group. QYD significantly restrained CaN and NFATc3 gene expression in the intestine, which was upregulated in the SAP group. Furthermore, QYD serum significantly decreased the LPS-induced elevation in intracellular free Ca2+ levels and inhibited cell death. CONCLUSION: QYD can exert protective effects against intestinal mucosa damage caused by SAP and the protective effects are mediated, at least partially, by restraining IEC apoptosis via the CaN/NFATc3 pathway.

Lathyrus sativus diamine oxidase reduces Clostridium difficile toxin A-induced toxicity in Caco-2 cells by rescuing RhoA-GTPase and inhibiting pp38-MAPK/NF-κB/HIF-1α activation.

Clostridium difficile toxin A (TcdA) impairs the intestinal epithelial barrier, increasing the mucosa permeability and triggering a robust inflammatory response. Lathyrus sativus diamino oxidase (LSAO) is a nutraceutical compound successfully used in various gastrointestinal dysfunctions. Here, we evaluated the LSAO (0.004-0.4 µM) ability to counter TcdA-induced (30 ng/mL) toxicity and damage in Caco-2 cells, investigating its possible mechanism of action. LSAO has improved the transepithelial electrical resistance (TEER) score and increased cell viability in TcdA-treated cells, significantly rescuing the protein expression of Ras homolog family members, A-GTPase (RhoA-GTPase), occludin, and zonula occludens-1 (ZO-1). LSAO has also exhibited an anti-apoptotic effect by inhibiting the TcdA-induced expression of Bcl-2-associated X protein (Bax), p50 nuclear factor-kappa-B (p50), p65nuclear factor-kappa-B (p65), and hypoxia-inducible transcription factor-1 alpha (HIF-1α), and the release of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and vascular endothelial growth factor (VEGF) in the cell milieu. Our data showed that LSAO exerts a protective effect on TcdA-induced toxicity in Caco-2 cells, placing itself as an interesting nutraceutical to supplement the current treatment of the Clostridium difficile infections.

Lathyrus sativus diamine oxidase counteracts histamine-induced cell proliferation, migration and pro-angiogenic mediators release in human colon adenocarcinoma cell line Caco-2.

Because histamine is a modulator of cancer cell proliferation and invasiveness, this study aimed at investigating the effect of Lathyrus sativus-derived diamine oxidase (LSAO) and its mechanism of action on Caco-2 cell line, considering that LSAO catalizes the oxidative deamination of histamine to the corresponding aldehyde, NH3 and H2 O2 . Histamine (0.01-1 µM) caused a proliferative effect on Caco-2 cells promoting cell migration, invasion and nitric oxide and vascular endothelial growth factor release. Histamine (1 µM) stimulus also down regulated occludin expression, favouring up regulation of pro-proliferative nuclear protein Ki67. Incubation with LSAO (0.004-0.4 µM) resulted in a significant inhibition of histamine-induced effects. LSAO rescued occludin expression and down regulated Ki67, and it inhibited histamine-induced increase of both MMP-2 and 9 expression. Histamine effects were mediated by RhoA-GTP down regulation and inversely related to phospho-p38MAPK/p50/65 up regulation. These effects were counteracted by LSAO incubation. Histamine catabolism by LSAO accounts for a significant down regulation of proliferation and invasiveness of Caco-2 cells. This study highlights the importance to control histamine levels in contrasting pro-angiogenic and metastatization capability of colon cancer cells and expands the knowledge about the diamine oxidase from L. sativus seeding as a phytotherapeutic approach for colon cancer.

Reactions of plant copper/topaquinone amine oxidases with N6-aminoalkyl derivatives of adenine.

Plant copper/topaquinone-containing amine oxidases (CAOs, EC 1.4.3.6) are enzymes oxidising various amines. Here we report a study on the reactions of CAOs from grass pea (Lathyrus sativus), lentil (Lens esculenta) and Euphorbia characias, a Mediterranean shrub, with N6-aminoalkyl adenines representing combined analogues of cytokinins and polyamines. The following compounds were synthesised: N6-(3-aminopropyl)adenine, N6-(4-aminobutyl)adenine, N6-(4-amino-trans-but-2-enyl) adenine, N6-(4-amino-cis-but-2-enyl) adenine and N6-(4-aminobut-2-ynyl) adenine. From these, N6-(4-aminobutyl) adenine and N6-(4-amino-trans-but-2-enyl)adenine were found to be substrates for all three enzymes (Km approximately 10(-4)M). Absorption spectroscopy demonstrated such an interaction with the cofactor topaquinone, which is typical for common diamine substrates. However, only the former compound provided a regular reaction stoichiometry. Anaerobic absorption spectra of N6-(3-aminopropyl)adenine, N6-(4-amino-cis-but-2-enyl)adenine and N6-(4-aminobut-2-ynyl)adenine reactions revealed a similar kind of initial interaction, although the compounds finally inhibited the enzymes. Kinetic measurements allowed the determination of both inhibition type and strength; N6-(3-aminopropyl)adenine and N6-(4-amino-cis-but-2-enyl)adenine produced reversible inhibition (Ki approximately 10(-5) - 10(-4) M) whereas, N6-(4-aminobut-2-ynyl)adenine could be considered a powerful inactivator.

A plant histaminase modulates cardiac anaphylactic response in guinea pig.

The effect of a copper amine oxidase (histaminase) purified from the pea seedling as free or immobilized enzyme on the response to specific antigen was studied in isolated hearts from actively sensitized guinea pigs. In vitro challenge with the specific antigen of hearts from actively sensitized animals evokes a positive inotropic and chronotropic effect, a coronary constriction, followed by dilation and an increase in the amount of histamine and nitrites, the oxidation product of nitric oxide, in the perfusates. In the presence of both forms of histaminases, the positive inotropic and chronotropic responses as well as the coronary constriction and the release of histamine were fully blocked. The amount of nitrites, appearing in the perfusates when anaphylaxis is elicited in the presence of both forms of histaminases, is significantly increased, as well as nitric oxide synthase activity and cyclic GMP content in cardiac tissue, while cardiac calcium overload was significantly prevented. These observations demonstrate that the decrease in the anaphylactic release of histamine and the subsequent abatement of the cardiac response to antigen can be accounted for by the inactivation by histaminase of the released histamine and by a stimulation of endogenous nitric oxide production.

Inhibition of cytolytic T lymphocyte maturation with ornithine, arginine, and putrescine.

L-Ornithine was shown to inhibit the development of cytolytic T lymphocytes (CTL) in mixed lymphocyte cultures (MLC). Lymphokines were unable to reverse the suppressive effect, and cytotoxic activity was not revealed by coupling ornithine-inhibited MLC cells to target cells with phytohemagglutinin (PHA). If addition of ornithine to MLC were delayed, sensitivity of CTL to inhibition was reduced after 24 hr and lost by 48 hr. Suppression of CTL development was not due to a toxic effect. MLC washed free of ornithine after 3 days produced detectable cytolytic activity within 24 hr of secondary culture, and to the same degree as the uninhibited MLC control within 48 hr. Cytotoxic cells generated in secondary cultures were Lyt-2+, did not kill the natural killer-sensitive YAC-1 cell line, and were shown to be antigen-specific by virtue of the findings that cytolysis and cold target inhibition were observed only with cells carrying the original, inducing H-2 haplotype. Cytolysis of target cells by normal CTL effector cells was not inhibited by L-ornithine. MLC depleted of accessory cells so that CTL activation was dependent upon addition of lymphokines remained susceptible to inhibition by ornithine. Our findings indicate that in the ornithine-inhibited MLC, CTL precursors undergo clonal expansion, but their maturation is arrested at a precytolytic stage. L-Arginine and putrescine also suppressed generation of CTL in primary MLC, and cells recovered from arginine- and putrescine-inhibited MLC developed control levels of CTL within 48 hr of secondary culture. Inhibition by putrescine was observed in tissue culture medium supplemented with human serum but not with fetal calf serum, presumably due to the presence of diamine oxidase activity in fetal calf serum. Similar to ornithine, the suppressive effects of arginine and putrescine on T lymphocytes were apparently selective for CTL because they did not inhibit mitogen activation with concanavalin A or the production of interleukin 2 and interleukin 3. These findings are consistent with a hypothesis that the inhibitory effects of ornithine, arginine, and putrescine are mediated by polyamines, and exerted on the differentiative stage of CTL development.

Diamine oxidase is important in assessment of polyamine effects on hemopoietic cell proliferation in vitro.

A difference was observed in the effect of difluoromethlyornithine (DFMO), a specific inhibitor of ornithine decarboxylase, on human and murine granulocyte-macrophage precursor cell (CFU-C) proliferation in vitro, in the presence of fetal bovine serum (FBS) and horse serum (HS). A dose of DFMO which almost totally abolished CFU-C colonies in cultures containing FBS had no effect or very little effect on CFU-C in cultures supplemented with HS. This effect could be reversed by aminoguanidine reacting with diamine oxidase (DAO), which is present in FBS but not in HS. The importance of DAO in the assessment of polyamine effects is also suggested by decreased colony formation in cultures containing HS and DFMO only after the addition of this enzyme. Additionally, Mo T cell line cultures containing DFMO demonstrated a substantially lower intracellular concentration of putrescine in the presence of FBS rather than HS.

Comparison of plasma histamine and cyclic nucleotides after antigen and methacholine inhalation in man.

Serial determinations of plasma histamine and cyclic nucleotides (adenosine monophosphate [AMP] and guanosine monophosphate [GMP]) were performed after inhalation of antigen and methacholine in four groups of subjects. In the first group, consisting of six antigen-sensitive subjects exhibiting bronchospasm after inhalation of ragweed or grass antigen, plasma histamine was elevated within 2 min and persisted for 30 min after inhalation of antigen. Peak histamine levels were between 18 to 80 ng/ml. In the second group, consisting of four nonatopic subjects, neither bronchospasm nor histamine was observed, despite inhalation of the same or 10-fold increased concentrations of antigen. In the third group, consisting of six subjects (three atopic and three nonatopic) exhibiting bronchospasm after inhalation of 2.5 to 10 mg of methacholine, sustained increases of histamine began at 1 min and persisted for 60 min after inhalation of methacholine. In the fourth group, seven subjects (two atopic, five nonatopic) without demonstrable bronchospasm despite inhalation of 2.5- to 10-fold increased doses of methacholine, no histamine was detected in the plasma at any time after inhalation of methacholine. Serial measurements of cyclic nucleotides showed no consistent changes in serum levels of cyclic AMP or cyclic GMP following inhalation challenge. We conclude that serum levels of histamine but not cyclic nucleotides change during bronchospasm induced by either antigen or methacholine.