GSTO1-1 is an upstream suppressor of M2 macrophage skewing and HIF-1α-induced eosinophilic airway inflammation.
Clin Exp Allergy 2020;
50:609-624. [PMID:
32052502 DOI:
10.1111/cea.13582]
[Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/05/2020] [Accepted: 02/10/2020] [Indexed: 02/04/2023]
Abstract
BACKGROUND
Glutathione S-transferases omega class 1 (GSTO1-1) is a unique member of the GST family regulating cellular redox metabolism and innate immunity through the promotion of LPS/TLR4/NLRP3 signalling in macrophages. House dust mite (HDM) triggers asthma by promoting type 2 responses and allergic inflammation via the TLR4 pathway. Although linked to asthma, the role of GSTO1-1 in facilitating type 2 responses and/or HDM-driven allergic inflammation is unknown.
OBJECTIVE
To determine the role of GSTO1-1 in regulating HDM-induced allergic inflammation in a preclinical model of asthma.
METHODS
Wild-type and GSTO1-1-deficient mice were sensitized and aeroallergen challenged with HDM to induce allergic inflammation and subsequently hallmark pathophysiological features characterized.
RESULTS
By contrast to HDM-challenged WT mice, exposed GSTO1-1-deficient mice had increased numbers of eosinophils and macrophages and elevated levels of eotaxin-1 and -2 in their lungs. M1 macrophage-associated factors, such as IL-1β and IL-6, were decreased in GSTO1-1-deficient mice. Conversely, M2 macrophage factors such as Arg-1 and Ym1 were up-regulated. HIF-1α expression was found to be higher in the absence of GSTO1-1 and correlated with the up-regulation of M2 macrophage markers. Furthermore, HIF-1α was shown to bind and activate the eotaxin-2 promotor. Hypoxic conditions induced significant increases in the levels of eotaxin-1 and -2 in GSTO1-deficient BMDMs, providing a potential link between inflammation-induced hypoxia and the regulation of M2 responses in the lung. Collectively, our results suggest that GSTO1-1 deficiency promotes M2-type responses and increased levels of nuclear HIF-1α, which regulates eotaxin (s)-induced eosinophilia and increased disease severity.
CONCLUSION & CLINICAL IMPLICATION
We propose that GSTO1-1 is a novel negative regulator of TLR4-regulated M2 responses acting as an anti-inflammatory pathway. The discovery of a novel HIF-1α-induced eotaxin pathway identifies an unknown connection between hypoxia and the regulation of the severity of allergic inflammation in asthma.
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