July 9, 2015, Ion Channel Retreat, Vancouver Ion Channel and Pain Targets Modulation of TRP channels by resolvins in mouse and human Ru-Rong Ji, PhD Pain Research Division Department of Anesthesiology Department of Neurobiology Duke University Medical Center
Omega-3 polyunsaturated fatty acids Powerful metabolic products (Resolvins) Ji et al., Trends Neurosci, 2011
Chronic pain is a major heath problem Over 100 million Americans have chronic pain The total financial cost of is near 600 billion a year in the US. Annual US expenditure on pain (medical costs and lost wages) is higher than that for cancer, heart disease, and diabetes combined. Co-morbidity: Chronic pain is associated with depression, anxiety, insomnia, etc. Prevention and treatment of this epidemic are equally important. Pizzo & Clark, N Engl J Med., 2012 American Pain Society
Peripheral mechanisms of pain Nociceptor Ji et al., Nat Rev Drug Disco., 2014
Central mechanisms of pain Tissue injury & Nerve injury DRG Primary afferents Microglia Activation p38-p ERK-P Persistent pain Glutamate BDNF Injury TNF-a IL-1b BDNF Glial mediators AMPA NMDA TrkB Excitation Astroglia activation CCL2 IL-1b JNK-P GABA-A-R Gly-R Spinal cord dorsal horn neurons Inhibition
Charles Serhan (RvE1) Serhan et al., 2008; Nature Reviews Immunology (RvD1)
Biosynthesis of resolvins from PUFA Precursors Aspirin:COX-2 RvE1 EPA LOX P450 18R-H(p)EPE microbial 17R-Resolvin D Series Acetylated COX-2 RvD1 DHA Aspirin:COX-2 LOX LOX RvD2 17S-Resolvin D Series Lipoxygenase mechanism
Resolvins are potent inhibitors of inflammation in various animal models Ji et al., Trends Neurosci, 2011
PWL (s) Resolvins prevent CRG-induced heat hyperalgesia Vehicle RvD1, 20 ng (60 pmol) RvE1, 20 ng (60 pmol) 12 10 * * * 8 6 4 2 0 BL 2 h 4 h 24 h Time after CRG Xu et al., Nat Med, 2010
Paw volume increase (% of BL) MPO activity (U mg 1 protein) RvE1 inhibits CRG-induced inflammation Paw edema Neutrophil infiltration 80 * 60 * * 60 40 40 20 20 0 CRG CRG+ (RvE1, 20ng) 0 Naive CRG CRG+ (RvE1, 20ng)
Fold of naïve control a RvE1 inhibits cytokine/chemokine expression after inflammation P 3 4 5 2 P TNF-a b P P 1 3 2 Naive P 30 25 * * * * * IL-1b IL-6 MCP-1 MIP-1a 4 5 20 # # # # # P 1 CRG, 2 h 15 c P 3 4 5 2 P 10 5 P 1 RvE1 + CRG, 2 h 0 CRG CRG+ (RvE1, 20ng) Cytokine array
No effect of RvE1 on basal pain
Broad actions of resolvins Ji et al., Trends Neurosci, 2011
ChemR23 expression in macrophages and microglia
ChemR23 expression in neurons in the PNS and CNS Ji et al., Trends Neurosci, 2011
RvE1 blocks capsaicin-induced signaling in mouse DRG neurons Control Capsaicin RvE1 + Capsaicin 340/380 300 nm Capsaicin 10 ng/ml RvE1 50 mm KCl 1.8 1.2 IC 50 = 3.2 ng/ml 1.6 1.0 1.4 0.8 1.2 1.0 0.6 0.8 0.4 0.6 RvE1 0.2 0.4 0.0 0 400 800 sec 0.1 1 10 ng/ml Inhibition ratio of capsaicin
Ratio of sepsc Duration of nocifensive behavior (s) RvE1 blocks TRPV1-mediated spinal synaptic transmission & pain Patch clamp recording Control Capsaicin (100 nm) RvE1 (1 ng ml) + Capsaicin 20 pa 6 s 3 2.5 2 1.5 1 * # Frequency Amplitude 50 40 30 * * * * * Capsaicin (500 ng, i.t) Capsaicin + RvE1 (10 ng, i.t.) 0.5 20 0 10 + Capsaicin (100 nm) 0 1 2 3 4 5 6 7 8 9 10 Time (min)
Resolvins are potent endogenous inhibitors of TRPV1/A1
Capsaicin and mustard oil-induced pain
Resolvin E1 (RvE1) blocks TRPV1 current in mouse DRG neurons 1 2 3 4 5 6 7 8 9 10 N TRPV1 ChemR23 GAPDH
ChemR23 is sufficient to mediate RvE1 s effect in HEK 293 cells TRPV1-expressing HEK cells Capsaicin (100 nm) RvE1 (10 ng/ml) TRPV1 and ChemR23-coexpressing HEK cells 100 pa 1 min
RvE1 fails to inhibit TRPV1 signaling in b-arrestin 2 KO mice WT b-arrestin 2 KO CAP (100 mm) RvE1 (10 ng/ml) 100 pa 1 min barr2 barr2 Control 20 mm RvE1 (10 ng/ml), 15 min
Number of flicking/licking/biting TRPV1 signaling is potentiated in b-arrestin 2 CKO mice M WT 1 2 3 4 5 N M barr2 CKO 1 2 3 4 5 N 20 16 CKO WT barr1 barr2 Nav1.8 GAPDH 12 8 4 0 0 1 2 3 4 5 6 7 8 9 10 Minutes after capsaicin injection
100 pa Ion channel research on Primary sensory neurons of human DRGs Single-cell PCR TLR7 TRPA1 TRPV1 GAPDH 1 2 3 4 5 6 7 8 9 10 neg let-7b (30 µm) let-7b (30 µm) HC030031(100 µm) 30 mm 10 s
Co-expression of TRPV1 and ChemR23 in human DRG neurons TRPV1 / ChemR23 100 mm
% of 1 st CAP response 1 na RvE1 inhibits TRPV1 currents in human DRG neurons CAP RvE1 CAP Capsaicin. Cap (100 nm) RvE1 (100 ng/ml) 25 µm 20 s RVE1 120 100 n = 3 / 3 n = 5 / 17 80 60 40 n = 12 / 17 20 0 10 ng/ml 100 ng/ml 100 ng/ml
Multiple beneficial effects of resolvins Anti-inflammatory actions Pro-resolution actions Block TNF-a synthesis and signaling Modulate synaptic plasticity Powerful endogenous inhibitors of TRPV1/A1 No effects on basal pain Unknown side effects Limitations Unstable Difficult to measure Expensive to produce
Biosynthesis of Protectins from PUFA Precursors Aspirin:COX-2 RvE1 EPA LOX P450 18R-H(p)EPE microbial Protectins Neuroprotectins NPD1 17R-Resolvin D Series Acetylated COX-2 Epoxidation RvD1 DHA Aspirin:COX-2 LOX LOX RvD2 17S-Resolvin D Series Lipoxygenase mechanism
Acknowledgements Zhen-Zhong Xu Chul-Kyu Park Ling Zhang Ning Lu Temugin Berta Supported by NIH grants R01: NS67686 R01: DE17794 R01: NS54932 R01: DE22743 R01: NS89479 Pfizer/Neusentis/Icagen Charles Serhan Seok-Yong Lee