Metformin attenuates the exacerbation of the allergic eosinophilic inflammation in high fat-diet-induced obesity in mice

A positive relationship between obesity and asthma has been well documented. The AMP-activated protein kinase (AMPK) activator metformin reverses obesity-associated insulin resistance (IR) and inhibits different types of inflammatory responses. This study aimed to evaluate the effects of metformin on the exacerbation of allergic eosinophilic inflammation in obese mice. Male C57BL6/J mice were fed for 10 weeks with high-fat diet (HFD) to induce obesity. The cell infiltration and inflammatory markers in bronchoalveolar lavage (BAL) fluid and lung tissue were evaluated at 48 h after ovalbumin (OVA) challenge. HFD obese mice displayed peripheral IR that was fully reversed by metformin (300 mg/kg/day, two weeks). OVA-challenge resulted in higher influx of total cell and eosinophils in lung tissue of obese mice compared with lean group. As opposed, the cell number in BAL fluid of obese mice was reduced compared with lean group. Metformin significantly reduced the tissue eosinophil infiltration and prevented the reduction of cell counts in BAL fluid. In obese mice, greater levels of eotaxin, TNF-α and NOx, together with increased iNOS protein expression were observed, all of which were normalized by metformin. In addition, metformin nearly abrogated the binding of NF-κB subunit p65 to the iNOS promoter gene in lung tissue of obese mice. Lower levels of phosphorylated AMPK and its downstream target acetyl CoA carboxylase (ACC) were found in lung tissue of obese mice, which were restored by metformin. In separate experiments, the selective iNOS inhibitor aminoguanidine (20 mg/kg, 3 weeks) and the anti-TNF-α mAb (2 mg/kg) significantly attenuated the aggravation of eosinophilic inflammation in obese mice. In conclusion, metformin inhibits the TNF-α-induced inflammatory signaling and NF-κB-mediated iNOS expression in lung tissue of obese mice. Metformin may be a good pharmacological strategy to control the asthma exacerbation in obese individuals.Fundação de Amparo à Pesquisa do Estado de São Paulo, 2012/14225-

Human eosinophil adhesion and degranulation stimulated with eotaxin and RANTES : Lack of interaction with nitric oxide-1

.1 mM), eotaxin (EOT; 100 ng/ml) or RANTES (RAN; 100 ng/ml) for 4 h (37°C, 5%CO), and then allowed to adhere to fibronectin-coated wells for 30 min. Results are expressed as mean adhered cell percentages of total cell number ± SEM (= 6). * P < 0.05 compared to control (CTRL).<p><b>Copyright information:</b></p><p>Taken from "Human eosinophil adhesion and degranulation stimulated with eotaxin and RANTES : Lack of interaction with nitric oxide"</p><p>http://www.biomedcentral.com/1471-2466/8/13</p><p>BMC Pulmonary Medicine 2008;8():13-13.</p><p>Published online 12 Aug 2008</p><p>PMCID:PMC2527293.</p><p></p

Human eosinophil adhesion and degranulation stimulated with eotaxin and RANTES : Lack of interaction with nitric oxide-0

or platelet-activating factor (PAF; 10M) for 4 h (37°C, 5%CO) and then allowed to adhere to fibronectin-coated wells for 30 min. Results are expressed as mean adhered cell percentages of total cell number ± SEM (= 6). * P < 0.05 compared to control (CTRL).<p><b>Copyright information:</b></p><p>Taken from "Human eosinophil adhesion and degranulation stimulated with eotaxin and RANTES : Lack of interaction with nitric oxide"</p><p>http://www.biomedcentral.com/1471-2466/8/13</p><p>BMC Pulmonary Medicine 2008;8():13-13.</p><p>Published online 12 Aug 2008</p><p>PMCID:PMC2527293.</p><p></p

Human eosinophil adhesion and degranulation stimulated with eotaxin and RANTES : Lack of interaction with nitric oxide-2

E methyl ester (L-NAME; 0.1 mM), eotaxin (EOT; 100 ng/ml) or RANTES (RAN; 100 ng/ml) for 4 h (37°C, 5%CO), and then were labelled with anti-α 4 (VLA-4; Panel A) or anti-αM (Mac-1; Panel B) antibodies. The results are expressed as mean fluorescence ± SEM (= 4).<p><b>Copyright information:</b></p><p>Taken from "Human eosinophil adhesion and degranulation stimulated with eotaxin and RANTES : Lack of interaction with nitric oxide"</p><p>http://www.biomedcentral.com/1471-2466/8/13</p><p>BMC Pulmonary Medicine 2008;8():13-13.</p><p>Published online 12 Aug 2008</p><p>PMCID:PMC2527293.</p><p></p

Cumulative concentration-response curves to carbachol (A and B), KCl (C and D) and CaCl₂ (E and F) in the presence of <i>in vitro</i> pre-incubated metformin (1 µM) or amlodipine (3 µM) in detrusor smooth muscle from lean and obese mice.

<p>Data represent the mean ± SEM for 4 to 7 mice each group. * p<0.05, ** p<0.01 compared with untreated group.</p

Effect of metformin treatment (300 mg/kg/day, two weeks) on the number of total inflammatory cells (A) and eosinophils (B) in bronchoalveolar lavage (BAL) fluid at 48 h following intranasal challenge with ovalbumin in sensitized mice.

<p>Each column represents the mean ± SEM (n = 10) for mice sensitized lean treated with vehicle (SL), sensitized obese treated with vehicle (SO), sensitized lean treated with metformin (SL + Met) and sensitized obese treated with metformin (SO + Met). *p<0.05.</p

Insulin tolerance test (ITT): (A) insulin sensitivity test after intraperitoneal injection of insulin (1.00 U/kg body wt) was performed on lean and obese groups.

<p>Blood samples were collected from the tail at indicated time points and analyzed for glucose concentration; (B) the constant rate for blood glucose disappearance (Kitt), based on the linear regression of the neperian logarithm of glucose concentrations, obtained from indicated time points. Results are expressed as mean ± SEM from 5–7 animals in each group.</p

Body weight, epididymal fat mass, bladder weight and glucose levels in lean and high-fat fed obese mice, treated or not with metformin (300 mg/kg/day, 14 days).

<p>Data represent the means ± SEM for 5–10 mice.</p>***<p>p<0.001 compared with lean group;</p>#<p>p<0.001 compared with respective obese group.</p