Research: CHIANG and COLLEAGUES,

Listed in Issue 271

Abstract

CHIANG and COLLEAGUES, 1. Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative and Pain Medicine, Harvard Institutes of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.#. Contributed equally investigated pathways in pathophysiology of infectious inflammation.

Background

Resolution of acute inflammation is an active process governed by specialized proresolving mediators, including resolvin (Rv)D2, that activates a cell surface G protein-coupled receptor, GPR18/DRV2.

Methodology

In this study, we investigated RvD2-DRV2-dependent resolution mechanisms using DRV2-deficient mice (DRV2-knockout [KO]).

Results

In polymicrobial sepsis initiated by cecal ligation and puncture, RvD2 (∼2.7 nmol/mouse) significantly increased survival (>50%) of wild-type mice and reduced hypothermia and bacterial titres compared with vehicle-treated cecal ligation and puncture mice that succumbed at 48 h. Protection by RvD2 was abolished in DRV2-KO mice. Mass spectrometry-based lipid mediator metabololipidomics demonstrated that DRV2-KO infectious exudates gave higher proinflammatory leukotriene B4 and procoagulating thromboxane B2, as well as lower specialized proresolving mediators, including RvD1 and RvD3, compared with wild-type. RvD2-DRV2-initiated intracellular signals were investigated using mass cytometry (cytometry by time-of-flight), which demonstrated that RvD2 enhanced phosphorylation of CREB, ERK1/2, and STAT3 in WT but not DRV2-KO macrophages. Monitored by real-time imaging, RvD2-DRV2 interaction significantly enhanced phagocytosis of live Escherichia coli, an action dependent on protein kinase A and STAT3 in macrophages.

Conclusion

Taken together, we identified an RvD2/DRV2 axis that activates intracellular signalling pathways that increase phagocytosis-mediated bacterial clearance, survival, and organ protection. Moreover, these results provide evidence for RvD2-DRV2 and their downstream pathways in pathophysiology of infectious inflammation.

References

Chiang N#1, de la Rosa X#1, Libreros S1, Serhan CN1. Novel Resolvin D2 Receptor Axis in Infectious Inflammation. J Immunol. 198(2):842-851. Jan 15 2017. doi: 10.4049/jimmunol.1601650. Epub Dec 19 2016.

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