Immunomodulatory and Anti-Inflammatory Potential of Curcumin for the Treatment of Allergic Asthma: Effects on Expression Levels of Pro-inflammatory Cytokines and Aquaporins.

Curcumin is well known for possessing anti-inflammatory properties and for its beneficial effects in the treatment of asthma. Current study investigates the immunomodulatory and anti-inflammatory effects of curcumin using mouse model of ovalbumin-induced allergic asthma. BALB/c mice were immunized with ovalbumin on day 0 and 14 to induce allergic asthma. Animals were treated with two different doses of curcumin (20 mg/kg and 100 mg/kg) and methylprednisolone from day 21 to 28. Mice were also daily challenged intranasally with ovalbumin during treatment period, and all groups were sacrificed at day 28. Histopathological examination showed amelioration of allergic asthma in treated groups as evident by the attenuation of infiltration of inflammatory cells, goblet cell hyperplasia, alveolar thickening, and edema and vascular congestion. Curcumin significantly reduced total and differential leukocyte counts in both bronchoalveolar lavage fluid and blood. Reverse transcription polymerase chain reaction analysis showed significantly suppressed mRNA expression levels of IL-4 and IL-5 (pro-inflammatory cytokines), TNF-α, TGF-ß (pro-fibrotic cytokines), eotaxin (chemokine), and heat shock protein 70 (marker of airway obstruction) in treated groups. Attenuation of these pro-inflammatory markers might have led to the suppression of airway inflammation. The expression levels of aquaporin-1 (AQP) and AQP-5 were found significantly elevated in experimental groups which might be responsible for reduction of pulmonary edema. In conclusion, curcumin significantly ameliorated allergic asthma. The anti-asthmatic effect might be attributed to the suppression of pro-inflammatory cytokines, and elevation of aquaporin expression levels, suggesting further studies and clinical trials to establish its candidature in the treatment of allergic asthma.

Amelioration of allergic asthma by Ziziphora clinopodioides via upregulation of aquaporins and downregulation of IL4 and IL5.

Ziziphora clinopodioides has been frequently used as an anti asthmatic plant in traditional medication. Recent work explores the anti-asthmatic activity of Z. clinopodioides in allergen-induced asthmatic mice. Intraperitoneal sensitization followed by intranasal challenge were given with ovalbumin (allergen) to develop allergic asthma. Investigational groups of animals were administered with drug methylprednisolone (MP) (15 mg/kg body weight), n-hexane fraction, ethylacetate fraction, and methanolic extract of Z. clinopodioides extract (500 mg/kg b.w.) for successive 07 days. Hematoxyline and eosin (H&E) and periodic acid-Schiff (PAS) stains were used to evaluate histopathological parameters on lung tissues. As an index of lungs tissues edema, wet/dry weight ratio of lungs was determined. Evaluation of expression levels of AQP1, AQP5, IL4, and IL5 was conducted by using RT-PCR. The data exhibited that both Z. clinopodioides and MP attenuated differential and total leukocyte counts in hematological examination i.e. in BALF and blood. Treatment with Z. clinopodioides also caused suppression of inflammatory cell infiltration and expression levels of IL4 and IL5, the later could have caused attenuation of pulmonary inflammation. The study also found decline in lung wet/dry ratio and goblet cellh hyperplasia in treated groups which indicates amelioration of lung edema. Treatment with Z. clinopodioides significantly increased the expression levels of aquaporin-1 and -5, which could have led to reduction in lung edema. The treatment with MP showed comparable results to Z. clinopodioides. Current investigation revealed that Z. clinopodioides possessed anti-asthmatic property which might be accredited to upregulagted AQP1 and AQP5 levels and downregulated IL4 and IL5 levels.

Mosla scabra flavonoids ameliorate the influenza A virus-induced lung injury and water transport abnormality via the inhibition of PRR and AQP signaling pathways in mice.

ETHNOPHARMACROLOGICAL RELEVANCE: Mosla scabra (Thunb.) C.Y. Wu and H.W. Li has been used as a traditional medicinal herb for centuries in East Asian countries. It has antibacterial, antiviral, antioxidant, anti-inflammatory and immunomodulatory effects. In folk medicine, it is used as a remedy for the treatment of pulmonary diseases, such as fever, cold, cough, pulmonary edema and emphysema. AIM OF THE STUDY: This study was to investigate the protective mechanism of total flavonoids from M. scabra (MF) in influenza A virus (IAV)-infected mice. MATERIALS AND METHODS: The mice were infected with IAV and then were treated daily with MF for five days. At the end of the experiment, the levels of inflammatory-related cytokines (IFN-α, IL-6, TNF-α and IL-1ß) were determined by ELISA. Pathological changes of lung tissue were examined by H&E staining. The protein expressions of AQP5, p-p38, caspase-3 and NF-κB p65 were detected by western blot analysis while the gene expressions of key effectors in AQP5 and PRRs signaling pathways were detected by real-time Fluorescence Quantitative Polymerase Chain Reaction (RFQ-PCR) analysis. RESULTS: The results showed that treatment with MF at doses of 120-360mg/kg for five days to IAV-infected mice significantly attenuated IAV-induced pulmonary injury and decreased the serum levels of IL-6, TNF-α and IL-1ß, but increased IFN-α levels. MF treatment could up-regulate the mRNA expressions of TLR-7, RIG-1, TRAF6, Bcl-2, Bax, VIPR1, PKCα and AQP5 and down-regulate caspase-3 and NF-κB p65 protein expression. CONCLUSION: Treatment with MF could significantly alleviate IAV-induced pulmonary inflammation, apoptosis and water transport abnormality, which was probably through the regulation of TLR7, RIG-1 and AQP5 signaling pathway.

Gating of aquaporins by heavy metals in Allium cepa L. epidermal cells.

Changes in the water permeability, aquaporin (AQP) activity, of leaf cells were investigated in response to different heavy metals (Zn(2+), Pb(2+), Cd(2+), Hg(2+)). The cell pressure probe experiments were performed on onion epidermal cells as a model system. Heavy metal solutions at different concentrations (0.05 µM-2 mM) were used in our experiments. We showed that the investigated metal ions can be arranged in order of decreasing toxicity (expressed as a decrease in water permeability) as follows: Hg>Cd>Pb>Zn. Our results showed that ß-mercaptoethanol treatment (10 mM solution) partially reverses the effect of AQP gating. The magnitude of this reverse differed depending on the metal and its concentration. The time course studies of the process showed that the gating of AQPs occurred within the first 10 min after the application of a metal. We also showed that after 20-40 min from the onset of metal treatment, the water flow through AQPs stabilized and remained constant. We observed that irrespective of the metal applied, the effect of AQP gating can be recorded within the first 10 min after the administration of metal ions. More generally, our results indicate that the toxic effects of investigated metal ions on the cellular level may involve AQP gating.

TNF-alpha-induced aquaporin 9 in synoviocytes from patients with OA and RA.

OBJECTIVES: To determine whether aquaporins (AQPs) are expressed in the synovial tissues of patients with OA and RA, and to examine the patterns of expression in patients with and without hydrarthrosis. METHODS: AQPs were detected in synovial tissue samples from patients with OA and RA using RT-PCR and immunohistochemistry. Fibroblast-like synoviocytes (FLSs) from patients with OA and RA were cultured and stimulated with TNF-alpha. The expression of AQPs in FLSs was examined using RT-PCR and western blot analyses and the function of aquaglyceroporins was examined by a glycerol uptake assay. RESULTS: AQP1, -3 and -9 mRNAs were expressed in synovial tissues from patients with OA and RA. AQP1, -3 and -9 proteins were also detected by immunohistochemistry. AQP9 mRNA was expressed more strongly in the synovial tissues of OA patients with hydrarthrosis than those without. AQP9 mRNA and protein expression were strongly induced with TNF-alpha treatment in FLSs, whereas the expression of AQP1 and -3 mRNAs was not induced with TNF-alpha treatment. AQP9 as an aquaglyceroporin was induced by TNF-alpha. CONCLUSIONS: AQP9 mRNA was detected in synovial tissues from OA and RA patients with hydrarthrosis. AQP9 expression was strongly induced in FLSs with TNF-alpha. Although the functions of AQP1, -3 and -9 in synovial tissues remain to be elucidated, it suggested that AQP9 might be related to the pathogenesis of hydrarthrosis and inflammatory synovitis.

Aquaporins as targets for drug discovery.

The intracellular hydric balance is an essential process of mammalian cells. The water movement across cell membranes is driven by osmotic and hydrostatic forces and the speed of this process is dependent on the presence of specific aquaporin water channels. Since the molecular identification of the first water channel, AQP1, by Peter Agre's group, 13 homologous members have been found in mammals with varying degree of homology. The fundamental importance of these proteins in all living cells is suggested by their genetic conservation in eukaryotic organisms through plants to mammals. A number of recent studies have revealed the importance of mammalian AQPs in both physiology and pathophysiology and have suggested that pharmacological modulation of aquaporins expression and activity may provide new tools for the treatment of variety of human disorders, such as brain edema, glaucoma, tumour growth, congestive heart failure and obesity in which water and small solute transport may be involved. This review will highlight the physiological role and the pathological involvement of AQPs in mammals and the potential use of some recent therapeutic approaches, such as RNAi and immunotherapy, for AQP-related diseases. Furthermore, strategies that can be developed for the discovery of selective AQP-drugs will be introduced and discussed.

Effects of glycyrrhizin on renal functions in association with the regulation of water channels.

It is well-known that the mineralocorticoid action of glycyrrhizin, which is the major component of Glycyrrhiza uralensis, is caused by a defect in the conversion of cortisol to cortisone by the inhibition of 11-beta-hydroxysteroid dehydrogenase enzyme activity. In the present study, we investigated the mechanisms of salt and water retention in the kidney of rats administered excess amounts of glycyrrhizin (200 mg/kg/day, p.o.). Up-regulation of aquaporin (AQP) 2 and 3 water channels was detected in the renal inner and outer medulla by Western blot analysis in rats treated with glycyrrhizin for 0.5, 1 and 2 consecutive weeks. Our results show that urine flow rates and sodium excretion rates in glycyrrhizin-treated rats were decreased significantly, but creatinine clearance (Ccr) was not altered. The decreases of urine volume and urinary sodium excretion in glycyrrhizin-treated rats were reversed by a 2-week injection of spironolactone, which is a well-known mineralocorticoid receptor (MR) blocker. These results suggest that the retention of water and salt in glycyrrhizin-treated rats is, at least in part, accounted for by the increased expression of AQP 2 and 3 in the kidney, which may be causally related to the MR.