GPR101 mediates the pro-resolving actions of RvD5n-3 DPA in arthritis and infections
Magdalena B. Flak, … , Francesco Palmas, Jesmond Dalli
Magdalena B. Flak, … , Francesco Palmas, Jesmond Dalli
Published December 3, 2019
Citation Information: J Clin Invest. 2020;130(1):359-373. https://doi.org/10.1172/JCI131609.
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Research Article Infectious disease Inflammation

GPR101 mediates the pro-resolving actions of RvD5n-3 DPA in arthritis and infections

Abstract

N-3 docosapentaenoic acid–derived resolvin D5 (RvD5n-3 DPA) is diurnally regulated in peripheral blood and exerts tissue-protective actions during inflammatory arthritis. Here, using an orphan GPCR screening approach coupled with functional readouts, we investigated the receptor(s) involved in mediating the leukocyte-directed actions of RvD5n-3 DPA and identified GPR101 as the top candidate. RvD5n-3 DPA bound to GPR101 with high selectivity and stereospecificity, as demonstrated by a calculated KD of approximately 6.9 nM. In macrophages, GPR101 knockdown limited the ability of RvD5n-3 DPA to upregulate cyclic adenosine monophosphate, phagocytosis of bacteria, and efferocytosis. Inhibition of this receptor in mouse and human leukocytes abrogated the pro-resolving actions of RvD5n-3 DPA, including the regulation of bacterial phagocytosis in neutrophils. Knockdown of the receptor in vivo reversed the protective actions of RvD5n-3 DPA in limiting joint and gut inflammation during inflammatory arthritis. Administration of RvD5n-3 DPA during E. coli–initiated inflammation regulated neutrophil trafficking to the site of inflammation, increased bacterial phagocytosis by neutrophils and macrophages, and accelerated the resolution of infectious inflammation. These in vivo protective actions of RvD5n-3 DPA were limited when Gpr101 was knocked down. Together, our findings demonstrate a fundamental role for GPR101 in mediating the leukocyte-directed actions of RvD5n-3 DPA.

Authors

Magdalena B. Flak, Duco S. Koenis, Agua Sobrino, James Smith, Kimberly Pistorius, Francesco Palmas, Jesmond Dalli

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Figure 8

Gpr101 knockdown limits the ability of RvD5n-3 DPA to activate host responses to promote the resolution of E. coli infections.

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Gpr101 knockdown limits the ability of RvD5n-3 DPA to activate host res...
(A) Mice were inoculated with 105 CFU E. coli via i.p. injection and lavages collected at the indicated time intervals before (0 hours) or after inoculation. RvD5n-3 DPA concentrations were determined using lipid mediator profiling. Results represent the mean ± SEM (n = 3 mice per group). (B) Mice were administered 9 μg siRNA against mouse Gpr101 or a scrambled control sequence, and after 72 hours, they were administered RvD5n-3 DPA (100 ng/mouse) or vehicle control (PBS containing 0.1% ethanol) and then inoculated with 105 CFU E. coli via i.p. injection. (C) Fourteen-hour exudate neutrophil counts. Results represent the mean ± SEM (n = 6 mice per group from 2 distinct experiments). (D and E) Bacterial phagocytosis was determined in exudate (D) neutrophils and (E) macrophages at the 14-hour interval using flow cytometry. (F) Efferocytosis was determined at the 14-hour interval in CD64+F4/80+ macrophages using flow cytometry. (G) The expression of MHC class II and IL-10R was assessed in CD64+F4/80+ macrophages using flow cytometry. Results represent the mean ± SEM (n = 6 mice per group from 2 distinct experiments). *P < 0.05 versus the vehicle-treated group; Kruskal-Wallis test with Dunn’s post hoc multiple comparisons test (C–G).