Effect of a plant histaminase on asthmalike reaction induced by inhaled antigen in sensitized guinea pig

Vegetal diamine oxidase alleviates histamine-induced contraction of colonic muscles

Excess of histamine in gut lumen generates a pronounced gastrointestinal discomfort, which may include diarrhea and peristalsis dysfunctions. Deleterious effects of histamine can be alleviated with antihistamine drugs targeting histamine receptors. However, many antihistamine agents come with various undesirable side effects. Vegetal diamine oxidase (vDAO) might be a relevant alternative owing to its histaminase activity. Mammalian intestinal mucosa contains an endogenous DAO, yet possessing lower activity compared to that of vDAO preparation. Moreover, in several pathological conditions such as inflammatory bowel disease and irritable bowel syndrome, this endogenous DAO enzyme can be lost or inactivated. Here, we tested the therapeutic potential of vDAO by focusing on the well-known effect of histamine on gut motility. Using ex vivo and in vitro assays, we found that vDAO is more potent than commercial anti-histamine drugs at inhibiting histamine-induced contraction of murine distal colon muscles. We also identified pyridoxal 5′-phosphate (the biologically active form of vitamin B6) as an effective enhancer of vDAO antispasmodic activity. Furthermore, we discovered that rectally administered vDAO can be retained on gut mucosa and remain active. These observations make administration of vDAO in the gut lumen a valid alternative treatment for histamine-induced intestinal dysfunctions.

Copper‑containing amine oxidase purified from Lathyrus sativus as a modulator of human neutrophil functions

Over the last few decades, copper‑containing amine oxidase (Cu‑AO) from vegetal sources, and belonging to the class of diamine oxidase, has been documented to exhibit beneficial effects in both in vivo and ex vivo animal models of inflammatory or allergic conditions, including asthma‑like reaction and myocardial or intestinal ischemia‑reperfusion injuries. The aim of the present study was to assess the potential of vegetal Cu‑AO as an anti‑inflammatory and an antiallergic agent and to clarify its antioxidant properties. In cell‑free systems, the reactive oxygen species and reactive nitrogen species scavenging properties of Cu‑AO that is purified from Lathyrus sativus were investigated. Its effect on the formyl‑methionyl‑leucyl‑phenylalanine peptide (fMLP)‑activated cellular functions of human neutrophils were subsequently analyzed. The obtained results demonstrated that Cu‑AO is not a scavenger of superoxide or nitric oxide, and does not decompose hydrogen peroxide. However, it inhibits the fMLP‑dependent superoxide generation, elastase release and cell migration, and interferes with the process of calcium flux, supporting the idea that plant Cu‑AO can interact with human neutrophils to modulate their inflammatory function. Therefore, the importance of these properties on the possible use of vegetal Cu‑AO to control inflammatory conditions, particularly intestinal inflammation, is discussed in the current study.

Poly(ADP-ribose) polymerase inhibition with HYDAMTIQ reduces allergen-induced asthma-like reaction, bronchial hyper-reactivity and airway remodelling

Activation of poly(ADP-ribose) polymerases (PARPs) is considered a key event in the molecular and cellular processes leading from acute asthma attacks to bronchial hyper-reactivity, leucocyte recruitment, chronic inflammation, airway remodelling and lung damage. The present investigation has been carried out to investigate the action of hydroxyl-dimethylaminomethyl-thieno[2,3-c]isoquinolin-5(4H)-one (HYDAMTIQ), a new potent PARP inhibitor, in the process leading from asthma-like events to airway damage. Ovalbumin-sensitized guinea pigs exposed two times to allergen inhalation were treated for 8 days with vehicle or HYDAMTIQ. Asthma-like signs, bronchial hyper-reactivity to methacholine, cytokine production, histamine release from mast cells, airway remodelling, collagen deposition and lung damage were evaluated. Repeated HYDAMTIQ administration (1-10 mg/kg/day i.p.) reduced lung PARP activity, delayed the appearance and reduced the severity of allergen-induced cough and dyspnoea and dampened the increased bronchial responses to methacholine. HYDAMTIQ-treated animals presented reduced bronchial or alveolar abnormalities, lower number of eosinophils and other leucocytes in the lung and decreased smooth muscle or goblet cell hyperplasia. The treatment also reduced lung oxidative stress markers, such as malondialdehyde or 8-hydroxy-2′-deoxyguanosine and the lung content of pro-inflammatory cytokines (TNF-α, interleukin (IL)-1β, IL-5, IL-6 and IL-18). Finally, mast cells isolated from the peritoneal or pleural cavities of sensitized, HYDAMTIQ-treated animals had a reduced ability to release histamine when exposed to ovalbumin in vitro. Our findings support the proposal that PARP inhibitors could have a therapeutic potential to reduce chronic lung inflammation, airway damage and remodelling in severe unresponsive asthmatic patients.

Carboxymethyl starch: Chitosan monolithic matrices containing diamine oxidase and catalase for intestinal delivery

The capacity of carboxymethyl starch (CMS):Chitosan monolithic tablets to protect diamine oxidase and/or catalase therapeutic enzymes against simulated gastric fluid (SGF) and to control their delivery in simulated intestinal fluid (SIF) was investigated. Enzyme formulations loaded with grass pea seedlings diamine oxidase (PSDAO) vegetal extract, catalase, or PSDAO associated to catalase, were obtained by direct compression. The CMS:Chitosan (1:1) matrix afforded a good gastric protection to PSDAO and to catalase, when each enzyme was formulated separately. Variable amounts of DAO were delivered in the SIF containing pancreatin, with maximal release reached at about 8h, a time convenient for tablets to attain the colon. Up to 50% of the initial enzymatic activity of catalase formulated with CMS:Chitosan was found after 8 h in SIF. For the CMS:Chitosan tablets of bi-enzymatic formulations containing PSDAO:Catalase, the releases of DAO and of catalase were synchronized. The hydrogen peroxide (product of DAO activity) was decomposed by the catalase liberated in the same SIF environment. The proposed formulations could allow novel therapeutic approaches for the treatment of inflammatory bowel diseases, intestinal cancers or pseudo-allergic reactions.

Zymographic assay of plant diamine oxidase on entrapped peroxidase polyacrylamide gel electrophoresis. A study of stability to proteolysis

A zymographic assay of diamine oxidase (DAO, histaminase, EC 1.4.3.6), based on a coupled peroxidase reaction, and its behavior at proteolysis in simulated gastric and intestinal conditions, are described. The DAO activity from a vegetal extract of Lathyrus sativus seedlings was directly determined on sodium dodecyl sulfate polyacrylamide electrophoretic gels containing entrapped horseradish peroxidase, with putrescine as substrate of histaminase and ortho-phenylenediamine as co-substrate of peroxidase. The accumulation of azo-aniline, as peroxidase-catalyzed oxidation product, led to well-defined yellow-brown bands on gels, with intensities corresponding to the enzymatic activity of DAO. After image analysis of gels, a linear dependency of DAO content (Coomassie-stained protein bands) and of its enzymatic activity (zymographic bands) with the concentration of the vegetal extract was obtained. In simulated gastric conditions (pH 1.2, 37 °C), the DAO from the vegetal extract lost its enzymatic activity before 15 min of incubation, either in the presence or absence of pepsin. The protein pattern (Coomassie-stained) revealed that the DAO content from the vegetal extract was kept almost constant in the simulated intestinal fluid (containing pancreatin or not), with a slight diminution in the presence of pancreatic proteases. After 10 h of incubation at 37 °C, the DAO enzymatic activity from the vegetal extract was 44.7% in media without pancreatin and 13.6% in the presence of pancreatin, whereas the purified DAO retained only 4.65% of its initial enzymatic activity in the presence of pancreatin.

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Histamine in food: is there anything to worry about?

Biogenic mono-, di- and poly-amines are widely distributed among living organisms. The amines fulfil many important functions in the human body both in the periphery and brain. Some authors suggest that foods rich in biogenic amines, especially histamine, present high health hazards for consumers. However, this is conditional on a range of other factors. The alimentary tract is well equipped with enzymes that inactivate amines and the blood-brain barrier prevents them entering the brain from the circulation. Oxidative deamination, methylation, acetylation and transglutamylation are the degradation pathways which operate efficiently in the stomach, intestines and liver. Particularly important is oxidative deamination. Food histamine poisoning or cheese reaction, manifested itself in patients treated with drugs that inhibit amine oxidases or in patients showing an enterocytic diamine oxidase deficit. It is rather food allergy, which should worry us more, as endogenous histamine release from mast cells is more dangerous. Preventive measures should be undertaken against increases in food allergies.

Amitriptyline affects histamine-N-methyltransferase and diamine oxidase activity in rats and guinea pigs

Histamine participates in numerous physiological and patophysiological processes. Drugs which interfere with the histamine actions are antagonists and agonists of histamine receptors. Histamine degrading enzymes as a possible target for modifying histamine action have so far not been extensively studied. Therefore we examined in vivo and in vitro effects of amitriptyline on two histamine degrading enzymes - diamine oxidase and histamine-N-methyltransferase. We were interested in the in vivo effects of amitriptyline on the diamine oxidase release into guinea pig plasma after heparin stimulation and in effects on the activity and gene expression of both histamine degrading enzymes in different guinea pig tissues. Amitriptyline's in vitro effects on the diamine oxidase and histamine-N-methyltransferase activities were measured in guinea pig and also in rat. Enzyme activities were determined with the radiometric micro-assay. The results showed that amitriptyline in vivo changed the profile of the heparin-induced diamine oxidase release, which could be due to changes in at least three processes: diamine oxidase release into plasma, protein synthesis and enzyme activity at the molecular level. Amitriptyline in some tissues (lung and spleen) amplified the mRNA expression of histamine degrading enzymes. Furthermore, the activities of these enzymes were increased in most examined tissues of amitriptyline treated guinea pigs. In vitro studies indicate that amitriptyline differently affects diamine oxidase and histamine-N-methyltransferase in two different rodent species, guinea pig and rat. Our study proved that amitriptyline enhances the histamine degrading processes in guinea pig, what might importantly contribute to lower histamine levels.

Substrate specificity of copper-containing plant amine oxidases

The steady-state kinetic parameters of the amine oxidases purified from Lathyrus cicera (LCAO) and Pisum sativum (PSAO) seedling were measured on a series of common substrates, previously tested on bovine serum amine oxidase (BSAO). LCAO, as PSAO, was substantially more reactive than BSAO with aliphatic diamines and histamine. The k(cat) and k(cat)/Km for putrescine were four and six order of magnitude higher, respectively. Differences were smaller with some aromatic monoamines. The plot of k(cat) versus hydrogen ions concentration produced bell-shaped curves, the maximum of which was substrate dependent, shifting from neutral pH with putrescine to alkaline pH with phenylethylamine and benzylamine. The latter substrates made the site more hydrophobic and increased the pK(a) of both enzyme-substrate and enzyme-product adducts. The plot of k(cat)/Km versus hydrogen ion concentration produced approximately parallel bell-shaped curves. Similar pK(a) couples were obtained from the latter curves, in agreement with the assignment as free enzyme and free substrate pK(a). The limited pH dependence of kinetic parameters suggests a predominance of hydrophobic interactions.

Beneficial effects of a plant histaminase in a rat model of splanchnic artery occlusion and reperfusion

Splanchnic artery occlusion (SAO) followed by reperfusion causes endothelial injury and inflammation which contribute to the pathophysiology of shock. We investigated the effects of pea seedling (Latyrus cicera) histaminase, known to afford protection against the deleterious effects of cardiac ischemia/reperfusion, given to rats subjected to SAO/reperfusion-induced splanchnic injury. Histaminase (80 IU kg, 15 min before reperfusion) significantly reduced the drop of blood pressure and high mortality rate caused by SAO/reperfusion. Histaminase also reduced histopathological changes, leukocyte infiltration (myeloperoxidase), and expression of endothelial cell adhesion molecules in the ileum. Histaminase counteracted free radical-mediated tissue injury, as judged by a significant decrease in the plasma and tissue levels of peroxidation and nitration products (oxidized rhodamine, malondialdehyde, nitrotyrosine), DNA damage markers (8-hydroxy-2'-deoxyguanosine, poly-adenosine diphosphate-ribosylated DNA) and consumption of tissue antioxidant enzymes (superoxide dismutase). As a result, histaminase led to a reduction of ileal cell apoptosis (caspase 3, terminal deoxynucleotidyltransferase-mediated UTP end labeling-positive cells). These results show that histaminase exerts a clear-cut protective effect in SAO/reperfusion-induced splanchnic injury, likely caused by oxidative catabolism of proinflammatory histamine and antioxidant effects resulting in hindrance of free radical-mediated tissue injury, endothelial dysfunction, and leukocyte recruitment. Thus, histaminase could be used therapeutically in intestinal ischemia.

Anti-inflammatory effect of amurensin H on asthma-like reaction induced by allergen in sensitized mice

AIM

To explore the anti-inflammatory effects of amurensin H on asthma-like reaction induced by allergen in sensitized mice.

METHODS

BALB/c mice were sensitized by ovalbumin (OVA, ip) on d 0 and d 14 and challenged with 1% OVA on d 18 to 22. Mice developed airway eosinophilia, mucus hypersecretion, and elevation in cytokine levels. Mice were administered amurensin H orally at the doses of 49, 70, or 100 mg/kg once every day from d 15 to the last day. Bronchoalveolar lavage fluid (BALF) were collected at 24 h and 48 h after the last OVA challenge. Levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 4 (IL-4), interleukin 5 (IL-5), and interleukin 13 (IL-13) in BALF were measured using ELISA method. Differential cell counts of macrophages, lymphocytes, neutrophils and eosinophils were performed in 200 cells per slide (one slide per animal). Lung tissue sections of 6-mum thickness were stained with Mayer's hematoxylin and eosin for assessment of cell infiltration, mucus production, and tissue damage.

RESULTS

Oral administration of amurensin H significantly inhibited OVA-induced increases in total cell counts, eosinophil counts, and TNF- alpha, IL-4, IL-5 and IL-13 levels in BALF. In addition, amuresin H dramatically decreased OVA-induced lung tissue damage and mucus production.

CONCLUSION

Amurensin H may have therapeutic potential for the treatment of allergic airway inflammation.