[Bronchial smooth muscle mitochondria: A new target for asthma therapy?]

Magnesium isoglycyrrhizinate alleviate airway inflammatory responses in ovalbumin-induced mouse model of allergic asthma

OBJECTIVE

Asthma is a common chronic airway inflammatory disease, lacking effective therapeutic approaches. Magnesium isoglycyrrhizinate (MgIG) is an anti-inflammatory drug for treating chronic inflammation. However, it is still ambiguous whether MgIG can function in allergy induced asthma. In this study, we investigated the anti-inflammation effect of MgIG in mice with allergy induced asthma and explored the underlying mechanisms.

METHODS

Mouse asthma model was established with ovalbumin (OVA) sensitization and challenge. Subsequently, mice sensitized with OVA were randomly assigned into fourgroups: asthma model group (MDL), dexamethasone group (DXM), MgIG group (MgIG), and normal mice were used as normal control (CON). The mice in MgIG, MDL were given 0.2 mg/ml MgIG solution by atomization inhalation for 30 min before 1% (w/v) OVA challenge. At the completion of model establishment and drug treatment, cells in bronchoalveolar lavage fluid were classified, inflammatory factors in serum were determined, histopathological analysis was performed by H&E staining, and expression of MUC5AC, NLRP3, and cleaved caspase-1 in the lung tissue was also determined by immunohistochemistry and western blotting, respectively.

KEY FINDINGS

In comparison to MDL group, MgIG treatment could significantly inhibit the recruitment of white blood cells, neutrophils, and eosinophils in BALF, reduced the production of IL-6, TNF-α, and IgE in serum, and reduced mucus secretion and the infiltration of inflammatory cells. Also, an increase of NLRP3 and Caspase-1 protein levels were suppressed by MgIG treatment.

CONCLUSION

Our study findings support that nebulizer inhalation of MgIG as an effective therapy in treating the allergy induced asthma.

Mitochondria are involved in bronchial smooth muscle remodeling in severe preschool wheezers

BACKGROUND

Bronchial remodeling is a key feature of asthma that is already present in preschoolers with wheezing. Moreover, bronchial smooth muscle (BSM) remodeling at preschool age is predictive of asthma at school age. However, the mechanism responsible for BSM remodeling in preschoolers with wheezing remains totally unknown. In contrast, in adult asthma, BSM remodeling has been associated with an increase in BSM cell proliferation related to increased mitochondrial mass and biogenesis triggered by an altered calcium homeostasis. Indeed, BSM cell proliferation was decreased in vitro by the calcium channel blocker gallopamil.

OBJECTIVE

Our aim was to investigate the mechanisms involved in BSM cell proliferation in preschoolers with severe wheezing, with special attention to the role of mitochondria and calcium signaling.

METHODS

Bronchial tissue samples obtained from 12 preschool controls without wheezing and 10 preschoolers with severe wheezing were used to measure BSM mass and establish primary BSM cell cultures. BSM cell proliferation was assessed by manual counting and flow cytometry, ATP content was assessed by bioluminescence, mitochondrial respiration was assessed by using either the Seahorse or Oroboros technique, mitochondrial mass and biogenesis were assessed by immunoblotting, and calcium response to carbachol was assessed by confocal microscopy. The effect of gallopamil was also evaluated.

RESULTS

BSM mass, cell proliferation, ATP content, mitochondrial respiration, mass and biogenesis, and calcium response were all increased in preschoolers with severe wheezing compared with in the controls. Gallopamil significantly decreased BSM mitochondrial biogenesis and mass, as well as cell proliferation.

CONCLUSION

Mitochondria are key players in BSM cell proliferation in preschoolers with severe wheezing and could represent a potential target to treat BSM remodeling at an early stage of the disease.