Carbon monoxide–based therapy ameliorates acute pancreatitis via TLR4 inhibition
Jing Xue, Aida Habtezion
Jing Xue, Aida Habtezion
Published December 16, 2013
Citation Information: J Clin Invest. 2014;124(1):437-447. https://doi.org/10.1172/JCI71362.
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Research Article Gastroenterology

Carbon monoxide–based therapy ameliorates acute pancreatitis via TLR4 inhibition

Abstract

The protective role of hemeoxygenase-1 (HO-1) in various inflammatory conditions is mediated in part by its products, carbon monoxide (CO) and biliverdin. Here we investigated a therapeutic role for CO and CO-primed cells in acute pancreatitis (AP). In a mouse model of AP, treatment with CO-releasing molecule–2 (CORM-2) decreased mortality, pancreatic damage, and lung injury. CORM-2 decreased systemic inflammatory cytokines, suppressed systemic and pancreatic macrophage TNF-α secretion, and inhibited macrophage TLR4 receptor complex expression. In both human and mouse cells, CORM-2 inhibited endogenous and exogenous ligand-dependent TLR4 activation, which indicates that CORM-2 could be therapeutic for both early and late stages of AP, which involve sterile- and endotoxin-mediated inflammation, respectively. Mice engrafted with TLR4-deficient hematopoietic cells were protected against caerulein-induced AP. In the absence of leukocyte TLR4 expression, CORM-2 did not confer additional protection, which indicates that CORM-2–dependent effects are mediated via suppression of macrophage TLR4 activation. We determined that CO was directly responsible for the protective effects of CORM-2 in AP, as inactive forms of CORM-2 were ineffective. Importantly, adoptive transfer of CORM-2–primed cells reduced AP. Such a therapeutic approach would translate the beneficial effects of CO-based therapies, avoiding CO- or CO-RM–mediated toxicities in AP and a wide range of diseases.

Authors

Jing Xue, Aida Habtezion

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Figure 3

CORM-2 inhibits TLR4-mediated TNF-α production in mouse and human monocytes/macrophages.

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CORM-2 inhibits TLR4-mediated TNF-α production in mouse and human monocy...
(A) Splenocytes from WT and TLR4 KO mice were isolated and pretreated with VE or CORM-2 for 1 hour, followed by stimulation with control or 100 ng/ml LPS for 4 hours in the presence of BFA. Frequency of TNF-α–positive macrophages (Lin–CD11b+CD11c–F4/80+) was determined by intracellular staining. Relative TNF-α expression was also quantified. Data are mean ± SEM. **P < 0.01. (B) BMDMs were prepared and pretreated with VE or CORM-2 for 1 hour, then stimulated with 10 ng/ml LPS or 100 ng/ml S100A8 for 4 hours in the presence of BFA. Relative TNF-α expression was also quantified. (C) Monocytes from human PBMCs were enriched and pretreated with VE or CORM-2 for 1 hour, then stimulated with 10 ng/ml LPS or 100 ng/ml HMGB1 for 4 hours in the presence of BFA. Relative TNF-α frequency in CD14+ circulating monocytes was determined by intracellular staining and quantified. Data are mean ± SEM of at least 3 independent experiments.