Phospholipase A2-dependent release of inflammatory cytokines by superantigen-stimulated nasal polyps of patients with chronic rhinosinusitis.

BACKGROUND: Chronic rhinosinusitis (CRS) is an inflammatory/allergic disease with unclear pathophysiology, but it has been linked to an imbalance in the production of eicosanoids, which are metabolites of arachidonic acid, and results from phospholipids hydrolysis by phospholipase A2 (PLA2). As of yet, the role of PLA2 in CRS has hardly been studied, except for a report that group II PLA2 expression is elevated in interleukin (IL) 1ß or tumor necrosis factor α-stimulated CRS nasal tissues with and without polyps. The PLA2 families include extracellular (secretory) and intracellular isoforms, which are involved in the regulation of inflammatory processes in different ways. Here we comprehensively investigated the expression of PLA2s, particularly those reported to be involved in respiratory disorders, in superantigen (SAE)-stimulated nasal polyps from patients with CRS with polyps, and determined their role in inflammatory cytokine production by inhibition of PLA2 expression. METHODS: The release of IL-5, IL-13, IL-17, and interferon γ by nasal polyps dispersed cells (NPDC) was determined concomitantly with PLA2 messenger RNA expression, under SAE stimulation, with or without dexamethasone, as a regulator of PLA2 expression. RESULTS: Stimulation of NPDCs by SAE-induced cytokine secretion with enhanced expression of several secretory PLA2 and Ca(2+)-independent PLA2, while suppressing cytosolic PLA2 expression. All these were reverted to the level of unstimulated NPDCs on treatment with dexamethasone. CONCLUSION: This study further supports the key role of secretory PLA2 in the pathophysiology of respiratory disorders and presents secretory PLA2 inhibition as a therapeutic strategy for the treatment of CRS and airway pathologies in general.

The pro-fibrotic effects of pregnancy in a carbon-tetrachloride-induced liver injury in mouse model.

BACKGROUND & AIMS: Immune cells interact with hepatic-stellate-cells (HSCs) in the development of liver fibrosis. Little is known about the influence of pregnancy on the development and progression of hepatic-fibrosis. In this study, we explored the influence of pregnancy on progression of hepatic fibrosis. METHODS: Female mice (C57Blc) were induced by 4 injections of peritoneal carbon-tetrachloride (CCl4) within 10 days, starting at day 10 of documented pregnancy. At end of experiment, serum samples were obtained for ALT and estradiol determination. Harvested livers were histological evaluated for liver injury and for protein αSMA expressions. Isolated intra-hepatic lymphocytes were assessed by flow cytometry. Isolated lymphocytes and serum samples were in- vitro co-cultured for 48 h with primary isolated naïve HSCs. Washed cells were analyzed for adherence (anti-αSMA+/anti-CD45 + ) and proliferations (CSFE). RESULTS: CCl4-model for liver injury was well tolerated when induced in pregnancy similar to non-pregnant state. Hepatic-fibrosis (Masson Trichrome Stain, Sirius red stain and αSMA expressions) and necro-inflammation (H&E stain and serum ALT levels) significantly increased in pregnancy. Increased liver injury was accompanied with pro-fibrotic lymphocyte profile; CD8 subsets increased and NK cells decreased. HSCs activation significantly increased when in-vitro cultured with lymphocytes from pregnant as compared to non-pregnant fibrotic ones. Pro-fibrotic profile was also explained by decreased NK activity (CD107a marker) and of their phagocytosis. Serum estradiol levels although elevated in fibrosis conditions of pregnancy was not associated with the pHSCs activations. CONCLUSION: Liver fibrosis in our murine model was severe in pregnant model; via pro-fibrotic lymphocyte and serum alterations.

Phospholipase A2 in experimental allergic bronchitis: a lesson from mouse and rat models.

BACKGROUND: Phospholipases A2 (PLA2) hydrolyzes phospholipids, initiating the production of inflammatory lipid mediators. We have previously shown that in rats, sPLA2 and cPLA2 play opposing roles in the pathophysiology of ovalbumin (OVA)-induced experimental allergic bronchitis (OVA-EAB), an asthma model: Upon disease induction sPLA2 expression and production of the broncho-constricting CysLTs are elevated, whereas cPLA2 expression and the broncho-dilating PGE2 production are suppressed. These were reversed upon disease amelioration by treatment with an sPLA2 inhibitor. However, studies in mice reported the involvement of both sPLA2 and cPLA2 in EAB induction. OBJECTIVES: To examine the relevance of mouse and rat models to understanding asthma pathophysiology. METHODS: OVA-EAB was induced in mice using the same methodology applied in rats. Disease and biochemical markers in mice were compared with those in rats. RESULTS: As in rats, EAB in mice was associated with increased mRNA of sPLA2, specifically sPLA2gX, in the lungs, and production of the broncho-constricting eicosanoids CysLTs, PGD2 and TBX2 in bronchoalveolar lavage (BAL). In contrast, EAB in mice was associated also with elevated cPLA2 mRNA and PGE2 production. Yet, treatment with an sPLA2 inhibitor ameliorated the EAB concomitantly with reverting the expression of both cPLA2 and sPLA2, and eicosanoid production. CONCLUSIONS: In both mice and rats sPLA2 is pivotal in OVA-induced EAB. Yet, amelioration of asthma markers in mouse models, and human tissues, was observed also upon cPLA2 inhibition. It is plausible that airway conditions, involving multiple cell types and organs, require the combined action of more than one, essential, PLA2s.

Triphala (PADMA) extract alleviates bronchial hyperreactivity in a mouse model through liver and spleen immune modulation and increased anti-oxidative effects.

OBJECTIVES: Triphala (TRP), a herbal extract from Tibetan medicine, has been shown to affect lymphocytes and natural killer T (NKT) cell function. We hypothesize that TRP could ameliorate bronchial hyperreactivity through immune-cell modulations. METHODS: Asthma mouse models were generated through intraperitoneal (IP) injections of ovalbumin (OVA)/2 weeks followed by repeated intranasal OVA challenges. Mice were then treated with normal saline (OVA/NS) or Triphala (OVA/TRP). Data were compared with mice treated with inhaled budesonide. All groups were assessed for allergen-induced hyperreactivity; lymphocytes from lungs, livers and spleens were analyzed for OVA-induced proliferation and their alterations were determined by flow cytometry. Oxidative reactivity using chemiluminescence, serum anti-OVA antibodies level and lung histology were assessed. RESULTS: Both TRP and budesonide significantly ameliorated functional and histological OVA-induced bronchial hyperreactivity. TRP had no effect on serum anti-OVA antibodies as compared with decreased levels following budesonide treatment. Furthermore, a significant increase in lung and spleen CD4 counts and a decrease in the liver were noted after TRP treatments. Bronchoalveolar fluid from TRP-treated animals but not from the budesonide-treated animals showed anti-oxidative effects. CONCLUSION: TRP and budesonide caused a significant decrease in bronchial reactivity. TRP treatment altered immune-cell distributions and showed anti-oxidative properties. These findings suggest that immune-cell modulation with TRP can ameliorate lung injury.

Oxidized cellulose binding to allergens with a carbohydrate-binding module attenuates allergic reactions.

Grass and mite allergens are of the main causes of allergy and asthma. A carbohydrate-binding module (CBM) represents a common motif to groups I (ß-expansin) and II/III (expansin-like) grass allergens and is suggested to mediate allergen-IgE binding. House dust mite group II allergen (Der p 2 and Der f 2) structures bear strong similarity to expansin's CBM, suggesting their ability to bind carbohydrates. Thus, this study proposes the design of a carbohydrate-based treatment in which allergen binding to carbohydrate particles will promote allergen airway clearance and prevent allergic reactions. The aim of the study was to identify a polysaccharide with high allergen-binding capacities and to explore its ability to prevent allergy. Oxidized cellulose (OC) demonstrated allergen-binding capacities toward grass and mite allergens that surpassed those of any other polysaccharide examined in this study. Furthermore, inhalant preparations of OC microparticles attenuated allergic lung inflammation in rye grass-sensitized Brown Norway rats and OVA-sensitized BALB/c mice. Fluorescently labeled OC efficiently cleared from the mouse airways and body organs. Moreover, long-term administration of OC inhalant to Wistar rats did not result in toxicity. In conclusion, many allergens, such as grass and dust mite, contain a common CBM motif. OC demonstrates a strong and relatively specific allergen-binding capacity to CBM-containing allergens. OC's ability to attenuate allergic inflammation, together with its documented safety record, forms a firm basis for its application as an alternative treatment for prevention and relief of allergy and asthma.

Immune modulation of ovalbumin-induced lung injury in mice using ß-glucosylceramide and a potential role of the liver.

CD1d-restricted natural killer T (NKT) cells are implicated in the pathogenesis of asthma. ß-Glucosylceramide (GC), a naturally occurring lipid, was previously shown to alter NKT cell distribution in the liver. We hypothesized that GC can affect lung and liver NKT cell distribution and ameliorate asthma. Mice were sensitized by intra-peritoneal injection of ovalbumin (OVA) for 2 weeks followed by repeated intranasal OVA challenges to induce lung injury mimicking asthma. OVA induced asthma groups were either treated by intranasal instillation of normal saline, intranasal instillation of GC or inhaled budesonide. To investigate the role of the liver, hepatic fibrosis was induced using carbon tetrachloride prior to asthma induction. Allergen induced bronchoconstriction was measured prior to sacrifice. Isolated lymphocytes from lungs, livers and spleens were analyzed for OVA induced proliferation and flow cytometry. Liver and lung histology, serum aminotransferase and anti-OVA antibodies level were assessed. Treatment with GC significantly reduced OVA induced airway responsiveness (p<0.001) similar to inhaled budesonide. GC significantly reduced the peri-bronchial and peri-vascular inflammatory infiltration mainly through an effect on T cells, as suggested by decreased T cell proliferation (p=0.009). Liver CD4 and NKT cells significantly increased after GC treatment suggesting liver involvement. Inducing hepatic fibrosis blunted the propagation of asthma in spite of sufficient increase of serum anti-OVA titers. GC has an immunomodulatory effect on a murine model of experimental asthma. We also suggest that the liver acts as an immunomodulatory organ and might have a regulatory effect on pulmonary diseases.