Background and purpose:Obesity is associated with deterioration in asthma outcomes. Although airways eosinophil accumulation is characteristic of lung allergic diseases, little is known about the influence of obesity on the allergic eosinophil trafficking from bone marrow to lung tissues, and recruitment to airways lumen. Here, we have assessed the effects of diet-induced obesity on allergic eosinophilic inflammation in mice, examining eosinophil trafficking from bone marrow to airways, and production of TH1/TH2 cytokines. Experimental approach: C57BL/6 mice fed for 10 weeks with standard chow or high-fat diet were sensitized and challenged with ovalbumin. At 24-96 h post-ovalbumin challenge, bronchoalveolar lavage (BAL) fluid, lung tissue and bone marrow were examined. Key results: The high-fat-fed mice exhibited increased body weight and epididymal fat, glucose intolerance and alterations in lipid profile compared with the lean mice. Obesity markedly elevated serum leptin and lowered adiponectin levels. Ovalbumin challenge in obese mice promoted a markedly higher eosinophil accumulation in bone marrow and connective tissue surrounding the bronchial and bronchiolar segments. Eosinophil number in BAL fluid of obese mice was lower at 24 and 48 h. Levels of interleukin (IL)-5, eotaxin, tumour necrosis factor-a and IL-10 in BAL fluid of obese mice were significantly higher than in lean mice. Conclusions and implications: Diet-induced obesity enhanced eosinophil trafficking from bone marrow to lung tissues, and delayed their transit through the airway epithelium into the airway lumen. Consequently, eosinophils remain longer in lung peribronchiolar segments due to overproduction of TH1/TH2 cytokines and chemokines.

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.

Study Type – Aetiology (case control) 
Level of Evidence 3b What’s known on the subject? and What does the study add? Erectile dysfunction (ED) is defined as the persistent inability to achieve and/or maintain an erection sufficient for satisfactory sexual performance. ED has been found in patients with cardiovascular and endocrine‐metabolic diseases. Overweight, obesity and weight gain have been shown to be independent risk factors for the development of ED. Clinical studies show that ED should be considered an early clinical manifestation of risk factors for cardiovascular events, including acute myocardial infarction. However, the mechanisms that explains ED associated with obesity are yet to be fully elucidated. Using a mice model of high‐fat diet associated with obesity, we have demonstrated that ED is the result of impaired endothelial and nitrergic cavernosal relaxations along with increased contractile responses, favouring penile detumescence. OBJECTIVE Obesity induced by high‐fat diet (HFD) is one of the most important risk factor for the development of erectile dysfunction (ED) in man. This study aimed to characterize the ED resulting from obesity associated with HFD in mice. MATERIALS AND METHODS C57BL/6 mice fed for 10 weeks with either HFD to induce obesity or a standard‐chow diet (SD) were used. Corpus cavernosum was surgically dissected free, and strips were mounted in 10‐mL organ baths containing Krebs solution. Functional responses to endothelium‐dependent and ‐independent agents, as well as to electrical‐field stimulation were measured in the cavernosal tissue. Levels of cGMP in erectile tissue were detected by enzyme immunoassay assay. RESULTS The potency (pEC50) and maximal response (Emax) to acetylcholine were significantly lower in the HFD group compared with the SD group. A marked decrease in the non‐adrenergic non‐cholinergic (nitrergic) cavernosal relaxations in the HFD group was also detected. There were no significant differences between the SD and HFD groups for the cavernosal relaxations in response to sodium nitroprusside. The contractile responses elicited by the α1‐adrenoceptor agonist phenylephrine were significantly greater in the HFD group compared with the SD group. Similarly, the electrical‐field stimulation (2–8 Hz)‐induced adrenergic contractions were markedly greater in HFD mice. The pEC50 for endothelin‐1 was about 6.9‐fold higher in the HFD compared with SD group. The basal cGMP content was 47% lower in HFD strips compared with SD group. There were no morphological alterations in erectile tissue of HFD group compared with SD mice. CONCLUSION Obesity associated with HFD favours ED as result of impaired endothelial and nitrergic cavernosal relaxations along with increased contractile responses to adrenergic stimulation and endothelin‐1 receptor activation.

Obesity/metabolic syndrome are common risk factors for overactive bladder. This study aimed to investigate the functional and molecular changes of detrusor smooth muscle (DSM) in high-fat insulin resistant obese mice, focusing on the role of protein kinase C (PKC) and Cav1.2 in causing bladder dysfunction. Male C57BL/6 mice were fed with high-fat diet for 10 weeks. In vitro functional responses and cystometry, as well as PKC and Cav1.2 expression in bladder were evaluated. Obese mice exhibited higher body weight, epididymal fat mass, fasting glucose and insulin resistance. Carbachol (0.001–100 µM), α,β-methylene ATP (1–10 µM), KCl (1–300 mM), extracellular Ca2+ (0.01–100 mM) and phorbol-12,13-dibutyrate (PDBu; 0.001–3 µM) all produced greater DSM contractions in obese mice, which were fully reversed by the Cav1.2 blocker amlodipine. Cystometry evidenced augmented frequency, non-void contractions and post-void pressure in obese mice that were also prevented by amlodipine. Metformin treatment improved the insulin sensitivity, and normalized the in vitro bladder hypercontractility and cystometric dysfunction in obese mice. The PKC inhibitor GF109203X (1 µM) also reduced the carbachol induced contractions. PKC protein expression was markedly higher in bladder tissues from obese mice, which was normalized by metformin treatment. The Cav1.2 channel protein expression was not modified in any experimental group. Our findings show that Cav1.2 blockade and improvement of insulin sensitization restores the enhanced PKC protein expression in bladder tissues and normalizes the overactive detrusor. It is likely that insulin resistance importantly contributes for the pathophysiology of this urological disorder in obese mice.

Macrophage migration inhibitory factor (MIF) is involved in eosinophil biology and in Type 2 inflammation, contributing to allergic and helminthic diseases. We hypothesized that MIF participates in the pathogenesis of eosinophilic esophagitis (EoE), an allergic condition characterized by esophageal eosinophilic inflammation. MIF is highly expressed in esophageal mucosa of patients with EoE, compared to gastro-esophageal reflux disease and control patients, where it co-localizes predominantly with eosinophils. In vitro, recombinant MIF promotes human eosinophil chemotaxis, while MIF antagonist and CXCR4 antagonist, AMD3100, revert this effect. In a model of EoE induced by ovalbumin, Mif deficient mice have reduced inflammation and collagen deposition compared to wild type mice. Importantly, treatment of wild type mice with anti-MIF or with AMD3100 during the challenge phase prevents accumulation of eosinophils and tissue remodeling. Conversely, recombinant MIF promoted tissue eosinophil inflammation in allergic mice. Together, these results implicate MIF in the pathogenesis of esophageal inflammation and suggest that targeting MIF might represent a novel therapy for EoE.