Synergistic cytoprotection by co-treatment with dexamethasone and rapamycin against proinflammatory cytokine-induced alveolar epithelial cell injury

Ken Kuwajima,Ai Furuta,Kyungho Chang,Masahiko Bougaki,Kanji Uchida,Yoshitsugu Yamada,Shigehito Sawamura

doi:10.1186/s40560-019-0365-5

Ken Kuwajima, Ai Furuta + Show 5 more

Open Access

https://doi.org/10.1186/s40560-019-0365-5

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Abstract

BackgroundOne of the main pathophysiological manifestations during the acute phase of sepsis is massive production of proinflammatory mediators. Clinical trials involving direct suppression of inflammatory mediators to relieve organ dysfunction in sepsis have been extensively performed; however, the clinical outcomes of such trials remain far from satisfactory. Given the need for better sepsis treatments, we have screened various agents with anti-inflammatory properties for cytoprotective effects. In this study, we identified dexamethasone and rapamycin as clinically applicable candidates with favorable synergistic effects against inflammatory cytokine-induced cytotoxicity in vitro and further explored the molecular mechanisms underlying the augmented cytoprotective effects exerted by co-treatment with both drugs.MethodsHuman alveolar epithelial cell-derived A549 cells were stimulated with a mixture of inflammatory cytokines, TNF-alpha, IL-1beta, and IFN-gamma, which induce cellular injury, including apoptosis. This in vitro model was designed to simulate acute lung injury (ALI) associated with sepsis. The cells were co-treated with dexamethasone and rapamycin under cytokine stimulation. Conditioned medium and cell lysates were subjected to further analysis.ResultsEither dexamethasone or rapamycin significantly attenuated cytokine-induced cytotoxicity in A549 cells in a dose-dependent manner. In addition, the simultaneous administration of dexamethasone and rapamycin had a synergistic cytoprotective effect. The applied doses of dexamethasone (10 nM) and rapamycin (1 nM) were considerably below the reported plasma concentrations of each drug in clinical setting. Interestingly, distinct augmentation of both of c-Jun inhibition and Akt activation were observed when the cells were co-treated with both drugs under cytokine stimulation.ConclusionsA synergistic protective effect of dexamethasone and rapamycin was observed against cytokine-induced cytotoxicity in A549 cells. Augmentation of both of c-Jun inhibition and Akt activation were likely responsible for the cytoprotective effect. The combined administration of anti-inflammatory drugs such as dexamethasone and rapamycin offers a promising treatment option for alveolar epithelial injury associated with sepsis.

Highlights

To mitigate hyper-inflammatory conditions, such as “cytokine storms” described during sepsis, clinical trials targeting inflammatory mediators have been extensively performed [1, 2]
The clinical outcomes of such trials remain far from satisfactory, it should be underlined that these inflammatory mediators can directly activate cellular apoptotic signal pathways [3], corresponding to the assumption that the sepsis-related organ dysfunction is closely associated with cellular apoptosis [4,5,6]
We observed the temporal changes in inflammat ion-associated protein expression induced by the cytokine mixture in A549 (Fig. 1b). inducible nitric oxide synthase (iNOS) and cox-2 induction peaked at 24 h after cytokine stimulation and cytokine stimulation

Summary

Introduction

To mitigate hyper-inflammatory conditions, such as “cytokine storms” described during sepsis, clinical trials targeting inflammatory mediators have been extensively performed [1, 2]. We evaluated the combination of dexamethasone [10] and rapamycin [11, 12] as clinically applicable candidates with favorable synergistic effects in vitro. We explored the molecular mechanisms underlying these cytoprotective effects against inflammatory cytokine-induced cytotoxicity in A549 cells. Clinical trials involving direct suppression of inflammatory mediators to relieve organ dysfunction in sepsis have been extensively performed; the clinical outcomes of such trials remain far from satisfactory. We identified dexamethasone and rapamycin as clinically applicable candidates with favorable synergistic effects against inflammatory cytokine-induced cytotoxicity in vitro and further explored the molecular mechanisms underlying the augmented cytoprotective effects exerted by co-treatment with both drugs

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Discussion

Conclusion