17-oxo-DHA displays additive anti-inflammatory effects with fluticasone propionate and inhibits the NLRP3 inflammasome.

Chiara Cipollina,Mark Gjomarkaj,Liboria Siena,Elisabetta Pace,Serena Di Vincenzo,Caterina Di Sano

doi:10.1038/srep37625

Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by reduced lung function associated with increased local and systemic inflammatory markers, such as TNFα and IL-1β. Glucocorticoids are used to treat this chronic disease, however their efficacy is low and new drugs are very much required. 17-oxo-DHA is a cyclooxygenase-2-dependent, electrophilic, α,β-unsaturated keto-derivative of docosahexaenoic acid with anti-inflammatory properties. We evaluated the action of 17-oxo-DHA alone or in combination with the steroid fluticasone propionate (FP) in peripheral blood mononuclear cells (PBMCs) from COPD patients and healthy individuals exposed to lipopolysaccharide. We show that PBMCs from COPD patients released higher levels of TNFα and IL-1β compared to controls. 17-oxo-DHA displayed strong anti-inflammatory effects. The addition of 17-oxo-DHA in combination with FP showed enhanced anti-inflammatory effects through the modulation of transcriptional and post-transcriptional mechanisms. 17-oxo-DHA, but not FP, was able to suppress the release of mature IL-1β through inhibition of the NLRP3 inflammasome. Furthermore, 17-oxo-DHA inhibited inflammasome-dependent degradation of the glucocorticoid receptor (GR). Our findings suggest that 17-oxo-DHA in combination with FP or other steroids might achieve higher therapeutic efficacy than steroids alone. Combined treatment might be particularly relevant in those conditions where increased inflammasome activation may lead to GR degradation and steroid-unresponsive inflammation.

Highlights

Cathepsin G and caspase-8, are able to convert the IL-1βprecursor into the mature form[10]
Transcriptional inhibition of TNFαand IL-1βmRNA by 17-oxo-docosahexaenoic acid (DHA) and fluticasone propionate (FP) was similar in lipopolysaccharides from Escherichia coli 0111:B4 (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) from chronic obstructive pulmonary disease (COPD) patients and healthy individuals. 17-oxo-DHA and FP when given alone significantly suppressed the transcription of TNFαand, when given in combination, displayed additive effects, to what observed when looking at the protein release profile. 17-oxo-DHA and FP inhibited LPS-induced IL-1βtranscriptional activation
We report that LPS-stimulated PBMCs from COPD patients released significantly higher levels of TNFαand IL-1βcompared to PBMCs from healthy individuals, in agreement with previous findings[31,32]

Summary

Introduction

Cathepsin G and caspase-8, are able to convert the IL-1βprecursor into the mature form[10]. Transcriptional inhibition of TNFαand IL-1βmRNA by 17-oxo-DHA and FP was similar in LPS-stimulated PBMCs from COPD patients and healthy individuals. The differences were not statistically significant, both compounds reduced LPS-induced NLRP3 transcription to a similar extent (Supplementary Figure S3 ) This suggested that the strong inhibition of IL-1βprotein release observed in response to 17-oxo-DHA was most likely due to post-transcriptional mechanisms of control. The effect of 17-oxo-DHA on inflammasome activation was evaluated by adding 17-oxo-DHA after LPS priming and before nigericin as previously reported[25,26]. The actions of 17-oxo-DHA and FP on inflammasome activation were further assessed by evaluating the formation of cleaved caspase-1 and IL-1βas well as the expression of NLRP3, pro-IL-1βand procaspase-1. 17-oxo-DHA inhibits the activation of multiple inflammasomes as well as nigericin-induced pyroptosome formation and mitochondrial ROS generation

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