Differential effects of lung inflammation on insulin resistance in humans and mice

Anti-inflammatory effects of reticuline on the JAK2/STAT3/SOCS3 and p38 MAPK/NF-κB signaling pathway in a mouse model of obesity-associated asthma

BACKGROUND

Asthma associated with obesity is a chronic disease characterized by earlier airway remodeling, severe wheezing, and increased insensitivity to hormone therapy. Reticuline, a bioactive compound of Magnoliae Flos, exerts anti-inflammatory activity and can inhibit neutrophil recruitment. Thus, this study investigated the role of reticuline in obesity-related asthma.

METHODS

The BALB/c mice fed a low-fat diet (LFD) and high-fat diet (HFD) were intranasally challenged with house dust mites (HDMs) or ovalbumin (OVA). Reticuline (0.25 mg/kg) was administrated into mice by intragastrical gavage. Airway hyper-responsiveness was examined after the final challenge. Body weight was measured, and bronchoalveolar lavage fluid (BALF) and lung tissues were collected. The number of inflammatory cells in BALF was estimated. Histological changes were assessed by performing hematoxylin-eosin staining, and production of proinflammatory cytokines and IgE was examined by ELISA kits. Related pathways were studied with western blotting.

RESULTS

Reticuline suppressed airway resistance and inflammatory infiltration in lung tissue and reduced inflammatory cell recruitment in BALF in obesity mice with asthma. Additionally, the levels of IL-17A, IL-1β, IL-5, macrophage inflammatory protein 2, and regulated on activation, normal T cell expressed and secreted in the lung were reduced by reticuline. Mechanistically, reticuline inactivated the JAK2/STAT3/SOCS3 and p38 MAPK/NF-κB signaling pathways in obesity-related asthma.

CONCLUSION

Reticuline alleviates airway inflammation in obesity-related asthma by inactivating the JAK2/STAT3/SOCS3 and p38 MAPK/NF-κB signaling pathways.

Protease-activated receptor-2: Role in asthma pathogenesis and utility as a biomarker of disease severity

PAR₂, a receptor activated by serine proteases, has primarily pro-inflammatory roles in the airways and may play a role in asthma pathogenesis. PAR₂ exerts its effects in the lungs through activation of a variety of airway cells, but also activation of circulating immune cells. There is evidence that PAR₂ expression increases in asthma and other inflammatory diseases, although the regulation of PAR₂ expression is not fully understood. Here we review the available literature on the potential role of PAR₂ in asthma pathogenesis and propose a model of PAR₂-mediated development of allergic sensitization. We also propose, based on our previous work, that PAR₂ expression on peripheral blood monocyte subsets has the potential to serve as a biomarker of asthma severity and/or control.