Inflammatory resolution is a process that, when uncontrolled, impacts many organs and diseases. As an active, self-limited inflammatory process, resolution involves biosynthesis of specialized proresolving mediators (SPM) (e.g., lipoxins, resolvins [Rv], protectins, and maresins). Because vagal stimulation impacts inflammation, we examined human and mouse vagus ex vivo to determine if they produce lipid mediators. Using targeted lipid mediator metabololipidomics, we identified lipoxins, Rv, and protectins produced by both human and mouse vagus as well as PGs and leukotrienes. Human vagus produced SPM (e.g., RvE1, NPD1/PD1, MaR1, RvD5, and LXA4) on stimulation that differed from mouse (RvD3, RvD6, and RvE3), demonstrating species-selective SPM. Electrical vagus stimulation increased SPM in both human and mouse vagus as did incubations with Escherichia coli. Electrical vagus stimulation increased SPM and decreased PGs and leukotrienes. These results provide direct evidence for vagus SPM and eicosanoids. Moreover, they suggest that this vagus SPM circuit contributes to a new proresolving vagal reflex.

The acute inflammatory response is critical in host defense and, when unresolved, can lead to chronic inflammation associated with many human diseases (1, 2). New therapeutic approaches are needed for diseases in which unresolved inflammation contributes to progressive loss of organ function. The vagus nerve–based inflammatory reflex uncovered by Tracey and colleagues (3) regulates immune function and inflammation. One mechanism of neural–immune control involves activation of macrophage α7 nicotinic acetylcholine receptors that inhibit proinflammatory cytokines. This macrophage α7 receptor inhibits NF-κB nuclear translocation and stimulates the JAK2/STAT3 pathway to reduce cytokines (4).

Mechanisms controlling the magnitude and duration of inflammatory responses have recently attracted considerable attention (1, 2). Self-limited acute inflammatory responses activate biosynthesis of novel specialized proresolving mediators (SPM) that stimulate resolution. SPM function by 1) limiting further neutrophil infiltration, 2) reducing collateral tissue damage, and 3) activating macrophages to engulf apoptotic cells and debris as well as 4) clearing microbial infections (2). The SPM include lipoxin (LX), resolvin (Rv), protectin (PD), and maresin (MaR) families biosynthesized from essential polyunsaturated fatty acids. Each SPM family member also counter-regulates cytokines, chemokines, and proinflammatory eicosanoids (e.g., PGF and leukotrienes [LT]) to reduce inflammation and activate IL-10 (2). Rv also block macrophage NLRP3 inflammasome, reducing IL-1β (5), and reduce pain (6, 7). Recently, new SPM structures containing peptide conjugates were elucidated that stimulate resolution and activate tissue regeneration (8).

We found that vagotomy delays resolution of inflammation (9). This delay involves shifting lipid mediators (LM) with reduced Rv to proinflammatory status, demonstrating a novel vagus-resolution circuit (9, 10). During bacterial infection, vagus also controls resolution via biosynthesis of specific SPM that function as immunoresolvents (e.g., PD conjugate in tissue regeneration [PCTR]1) upregulated by acetylcholine via ILC-3 control of macrophage SPM biosynthesis and phenotype (10).

In view of these findings, we investigated whether vagus can directly produce LM. In this article, we report that human vagus produces specific SPM, identified using liquid chromatography–tandem mass spectrometry (LC-MS/MS)–based metabololipidomics, that differed from those produced by mouse vagus. Escherichia coli increased LM-SPM, and electrical vagus stimulation (EVS) ex vivo increased SPM and reduced both PGs and LT.

Fresh human vagi (deidentified) purchased from Tissue for Research (Ellingham, Bungay, Suffolk, U.K.) were analyzed under protocol no. 1999P0001279 approved by the Partners Human Research Committee. Each postmortem, full-length human vagus was thawed on arrival, measured, dissected, and incubated in PBS (with calcium and magnesium) for 20 min at 37°C with 5% CO2 in parallel with direct EVS with 2.5 mA 18 V direct current (DC) for 20 min in PBS at 37°C (ApeX Type A stimulator; ApeX Electronics, Schenectady, NY), or coincubated with E. coli (109 CFU for 3 h at 37°C). Deuterium-labeled standards for SPM and eicosanoid extraction recoveries were from Cayman Chemical (Ann Arbor, MI). For abbreviations and stereochemical assignments with the full name for each of the SPM, see (11, 12). Animal experimental procedures were approved by the Institutional Animal Care and Use Committee of Brigham and Women’s Hospital (protocol no. 2016N000145) and complied with institutional and U.S. National Institutes of Health guidelines. Six- to eight-week-old FVB male mice (Charles River Laboratories, Wilmington, MA) were fed ad libitum Laboratory Rodent Diet 20-5058 (Purina Mills, Great Summit, MO).

Cold methanol containing deuterium-labeled (12) internal standards (500 pg/sample) were added to all samples. Following solid-phase extraction, LM-SPM were identified and quantified as in Ref. 13 and, for cysteinyl LT (CysLT), using LC-MS/MS and published criteria (i.e., six ions) (12, 13). Linear calibration curves were obtained using d5-LTC4, d5-LTD4, d2-PCTR3, and others (12), giving r2 values of 0.98–0.99.

Results are mean ± SEM. Significance was calculated using one-tailed paired t test and GraphPad Prism software (La Jolla, CA). The p values were *p < 0.05 and **p < 0.01.

To determine if human vagus directly produces LM that could impact inflammation via the neural reflex (3), we assessed LM profiles with fresh human vagus. To this end, using LC-MS/MS–based LM metabololipidomics together with spectral libraries of MS/MS (1113), we identified in human vagus specific mediators from each major bioactive LM-SPM metabolome. (Fig. 1A, Supplemental Table I). These included Rv, PD, and MaR from DHA, E-series Rv from EPA, arachidonic acid–derived LX, LT, thromboxane, and PGs, as well as CysLT (LTC4, LTD4). For each, LC-MS/MS results gave at least six diagnostic ions for identification (Fig. 1B).

FIGURE 1.

Human vagus produces endogenous SPM and eicosanoids. Fresh postmortem human vagi were dissected and cold methanol was added containing deuterium-labeled internal standards. LM were identified and quantified using LC-MS/MS (see 2Materials and Methods). (A) LC-MS/MS chromatographs. (B) MS/MS spectra with diagnostic ions for RvD3, RvD4, RvD5, RvE1, MaR1, and NPD1/PD1 are representative of six different vagi from three human subjects. (C) LM network visualization of unstimulated vagus using Cytoscape 3.6.1 software and quantitation using LC-MS/MS values. Circle size in picograms. Black circle, not detected; Gray square, transient intermediates not monitored. Results are mean values. (A)–(C) are representative of six different human vagi from three subjects.

FIGURE 1.

Human vagus produces endogenous SPM and eicosanoids. Fresh postmortem human vagi were dissected and cold methanol was added containing deuterium-labeled internal standards. LM were identified and quantified using LC-MS/MS (see 2Materials and Methods). (A) LC-MS/MS chromatographs. (B) MS/MS spectra with diagnostic ions for RvD3, RvD4, RvD5, RvE1, MaR1, and NPD1/PD1 are representative of six different vagi from three human subjects. (C) LM network visualization of unstimulated vagus using Cytoscape 3.6.1 software and quantitation using LC-MS/MS values. Circle size in picograms. Black circle, not detected; Gray square, transient intermediates not monitored. Results are mean values. (A)–(C) are representative of six different human vagi from three subjects.

Close modal

Human vagus produced several Rv, including RvE1 and specifically RvD3, RvD4, and RvD5 (Fig. 1B). The Rv of human vagus did not include RvD1, RvD2, RvE2, or RvE3, which are produced by human leukocytes, lymph nodes, spleen (11), and emotional tears (13). These results indicate that, although some tissues produce all of the known d-series Rv (RvD1–RvD6), human vagus produces those biosynthesized via the 4(5)-epoxy-Rv intermediate rather than those from 7(8)-epoxy-Rv intermediate (i.e., RvD1 and RvD2) (compare Refs. 11, 13). D-series Rv control inflammation resolution, infection, and pain reduction (2, 8).

Human vagus also produced both PD and MaR pathways. This was concluded through identification of neuroprotectin D1 (NPD1/PD1) and its pathway marker (Fig. 1), biosynthesized via double lipoxygenation, namely 10S,17S-diHDHA (PDX) (14). Also, 17R-NPD1/PD1 was identified in human vagus (Fig. 1A). NPD1/PD1 stimulates resolution and is neuroprotective (15). This 17R epimer of NPD1/PD1 is longer acting and is produced via acetylated COX-2 following aspirin or by p450, which can produce the precursor 17R-hydroxydocosahexaenoic acid (16). Hence, 17R-NPD1/PD1 may have resulted from aspirin use by the organ donors. Alternately, aspirin-triggered Rv (17R epimer) and LX (15R epimer) are also produced by a new pathway in neural tissues that uses sphingosine kinase 1 to acetylate COX-2 as a mechanism to biosynthesize aspirin-triggered epimers of SPM (17). These longer-acting endogenous epimers of SPM are potent proresolving agonists (2). Human vagus also produced MaR1 and its pathway marker, 7S,14S-dihydroxy-DHA (Fig. 1). In addition to MaR1’s potent proresolving actions with human leukocytes (2, 14) and platelets (18), MaR1 is neuroprotective and activates recovery from spinal cord injury (19).

In human vagus, SPM from arachidonic acid (i.e., LXA4 and LXB4) were also identified (Fig. 1). Along with their ability to activate resolution (2), LXA4 reduces neuroinflammation and neuropathic pain following hemisection of spinal cord via reducing microglial activation (20), and both LXA4 and LXB4 are neuroprotective (21). Thus, their production by human vagus, as well as other SPM documented in this article from their physical properties, is of interest as potential mediators from vagal stimulation.

Electrical stimulation of human vagus increased RvD4 and MaR1, with trends for increases in other vagus SPM (Supplemental Table I). RvD4 is found in human bone marrow and controls bacterial clearance (22). Vagus expresses Toll receptors (3), and incubations with live E. coli increased both RvD4 and RvD6, as well as increased 15-epi-LXA4 and MaR1, which may together stimulate clearance of infections. RvD6 was not present in vagus alone or with electrical stimulation (Supplemental Table I). Fig. 1C shows the vagus LM network, depicting quantification, biosynthetic relationships between precursors, bioactive LM, and pathway marker products of each bioactive metabolome.

Because specific SPM were present in human vagus, we investigated LM of mouse vagus. For this, fresh mouse vagi were incubated, which demonstrated that LM profiles in mice differed from profiles in humans (Supplemental Fig. 1, Supplemental Tables I and II). Three mouse strains produced the same SPM (Supplemental Table III). Mouse vagus produced RvD4, RvE1, RvE3, LXB4, and 15-epi-LXA4. Mouse vagus with E. coli increased biosynthesis of only PDX, suggesting that this SPM may play a role in vagus control of infection, whereas human vagus increased several SPM (e.g., RvD4, NPD1, MaR1, 18-HEPE, and 15-epi-LXA4) that are each potent proresolving mediators. Interestingly, RvD3 was selectively increased with EVS (vide infra). Multivariate analysis of LM profiles obtained from human or mouse vagus profiles demonstrated a strong association between different species (Supplemental Fig. 1D); the sphere in the three-dimensional score plot represents 95% confidence. Principal component analysis (PCA) confirmed that RvD6, RvE3, and RvD4 were associated with mouse vagus, whereas RvD5, RvE1, MaR1, and NPD1 were associated with human vagus (Supplemental Fig. 1D).

We next investigated whether EVS ex vivo also led to LM production. After 20 min of electrical stimulation, we found a specific group of SPM was increased. PCA confirmed that mouse vagus nerve subjected to EVS clustered separately compared with control (Fig. 2A). In multivariate analysis, RvD4, RvE1, RvD3, and PDX were associated with EVS (Fig. 2B). Also, quantitation of the increase in SPM gave a statistically significant increase of ∼3× the sum of RvD3, RvD4, and RvE1. Interestingly, prostanoids and thromboxane were reduced by EVS (Fig. 2C), as were LTC4, LTD4, and LTE4 (Fig. 2D, Supplemental Table II). These findings identify LM of human and mouse vagus as well as, to our knowledge, the first evidence of vagus SPM production. Together, the present findings identify SPM as vagal products that are known controllers of host response to inflammation and infection (2, 5, 14).

FIGURE 2.

Vagus electrical stimulation of SPM production and reduction of eicosanoids. Mouse vagus was incubated (20 min at 37°C with 5% CO2) and electrically stimulated (2.5 mA 18 V direct DC for 20 min). Bioactive metabolomes were identified and quantified as in Fig. 1A. (A) PCA three-dimensional (3D) score plot. (B) Loading two-dimensional (2D) plot shows endogenous LM. (C) RvD3, RvD4, RvE1, RvE3, and LXB4 (left) increased; LTB4, PGD2, PGE2, PGF, and TxB2 (right) diminished. (D) CysLT identification (left); LT decreased after EVS (right). (E) LM-SPM network pathways visualized with Cytoscape (3.6.1), with mean value changes between unstimulated and stimulated vagi. Upregulated LM are shown in red, downregulated LM are shown in blue. Black circles, not detected; Gray squares, not monitored. (A) and (B) are representative of three independent animals. Results in (C) and (D) are mean ± SEM. *p < 0.05, one-tailed t test.

FIGURE 2.

Vagus electrical stimulation of SPM production and reduction of eicosanoids. Mouse vagus was incubated (20 min at 37°C with 5% CO2) and electrically stimulated (2.5 mA 18 V direct DC for 20 min). Bioactive metabolomes were identified and quantified as in Fig. 1A. (A) PCA three-dimensional (3D) score plot. (B) Loading two-dimensional (2D) plot shows endogenous LM. (C) RvD3, RvD4, RvE1, RvE3, and LXB4 (left) increased; LTB4, PGD2, PGE2, PGF, and TxB2 (right) diminished. (D) CysLT identification (left); LT decreased after EVS (right). (E) LM-SPM network pathways visualized with Cytoscape (3.6.1), with mean value changes between unstimulated and stimulated vagi. Upregulated LM are shown in red, downregulated LM are shown in blue. Black circles, not detected; Gray squares, not monitored. (A) and (B) are representative of three independent animals. Results in (C) and (D) are mean ± SEM. *p < 0.05, one-tailed t test.

Close modal

Vagus from human and mouse also produces PGD2, PGE2, and PGF (Figs. 1, 2) as well as LT. LTB4 is a potent chemoattractant, and CysLT (LTC4, LTD4, and LTE4) are appreciated for their production by mast cells and role as slow-reacting substance of anaphylaxis in allergic reactions (23). However, CysLT may also possess physiologic functions in neural and endocrine systems, as in pineal gland control of hormone release (23). Because CysLT are potent smooth-muscle constrictors and stimulate vascular permeability (23), their vagus production is of interest and may contribute to neural reflex pathways that can modulate organ function. Novel SPM such as PCTR1, regulated by vagal stimulation of ILC3 to control infection (10), along with maresin conjugates in tissue regeneration and resolvin conjugates in tissue regeneration (12), were not present in either mouse or human vagus, in contrast to LTC4, LTD4, and LTE4. EVS of mouse vagus increased SPM that included LXB4, RvE1, RvD3, and RvD4 (Fig. 2A–C). This was accompanied by decreases in both PGs and CysLT (Fig. 2C–E). These findings indicate that vagus stimulation increases proresolving mediators that can directly stimulate resolution of inflammation and infections by virtue of their actions on phagocytes and reduce chemokines, cytokines, and proinflammatory LM as well as enhance microbial killing and clearance (2). Also, Rv (e.g., RvE1) reduce pain via SPM receptors on neurons (7).

In PGE synthase-1 (mPGE1) knockout mice, vagus stimulation is abolished, implying that absence of PGE2 is critical to the cholinergic anti-inflammatory pathway (24). In resolution of contained exudates, PGE2 signals LM class switching, increasing SPM (2). Vagus nerve also responds with cytokine-specific neural signals (25) that can contribute to systemic inflammation. Additional regulators of inflammation resolution that possibly may be vagus controlled include hypoxia-inducible factors, purinergic signaling, and miRNAs (2628), which interact with SPM (2). Vagus-stimulating devices in arthritis patients target the inflammatory reflex, reducing TNF-α, IL-1β, and IL-6 (29).

Our results demonstrate that isolated human vagi produce specific SPM, suggesting that EVS may activate resolution of inflammation via SPM and downregulation of PGs and LT. Excess PG and LTB4 are known to contribute to chronic inflammation (23). Network mapping in the immune system (Figs. 1, 2) can highlight species differences in physiologic and pathologic networks (30). The present results demonstrate species differences with human SPM, in that, with EVS, human vagus produced MaR1 and RvD4 (Fig. 1, Supplemental Table I). RvD4 is produced by both human and mouse vagus, suggesting proresolving functions are intact in both species. Hence, these results document vagus proresolving capacity, with human and mouse vagus directly producing LX, Rv, and PD in amounts commensurate with their potent pico- to nanogram actions (2) that can impact multiple organs and immune cells. They also demonstrate that EVS increases SPM and diminishes PGs and LT that are known to contribute to chronic inflammation and allergic responses (23). Together, these results, to our knowledge, identify a new vagus proresolving reflex that may be targeted via electrical stimulation to improve disease treatments in which Rv and unresolved inflammation are involved as well as to possibly improve overall health status.

We thank Mary Halm Small for expert assistance in manuscript preparation.

This work was supported in part by National Institutes of Health Grant R01GM038765 (to C.N.S.).

The online version of this article contains supplemental material.

Abbreviations used in this article:

CysLT

cysteinyl LT

DC

direct current

EVS

electrical vagus stimulation

LC-MS/MS

liquid chromatography–tandem mass spectrometry

LM

lipid mediator

LT

leukotriene

LX

lipoxin

MaR

maresin

NPD1/PD1

neuroprotectin D1

PCA

principal component analysis

PCTR

PD conjugate in tissue regeneration

PD

protectin

PDX

10S,17S-diHDHA

Rv

resolvin

SPM

specialized proresolving mediator.

1
Perretti
,
M.
2015
.
The resolution of inflammation: new mechanisms in patho-physiology open opportunities for pharmacology.
Semin. Immunol.
27
:
145
148
.
2
Serhan
,
C. N.
2014
.
Pro-resolving lipid mediators are leads for resolution physiology.
Nature
510
:
92
101
.
3
Pavlov
,
V. A.
,
K. J.
Tracey
.
2012
.
The vagus nerve and the inflammatory reflex--linking immunity and metabolism.
Nat. Rev. Endocrinol.
8
:
743
754
.
4
Báez-Pagán
,
C. A.
,
M.
Delgado-Vélez
,
J. A.
Lasalde-Dominicci
.
2015
.
Activation of the macrophage α7 nicotinic acetylcholine receptor and control of inflammation.
J. Neuroimmune Pharmacol.
10
:
468
476
.
5
Lopategi
,
A.
,
R.
Flores-Costa
,
B.
Rius
,
C.
López-Vicario
,
J.
Alcaraz-Quiles
,
E.
Titos
,
J.
Clària
.
2018
.
Frontline science: specialized proresolving lipid mediators inhibit the priming and activation of the macrophage NLRP3 inflammasome.
J. Leukoc. Biol.
DOI: 10.1002/jlb.3hi0517-206rr.
6
Huang
,
J.
,
J. J.
Burston
,
L.
Li
,
S.
Ashraf
,
P. I.
Mapp
,
A. J.
Bennett
,
S.
Ravipati
,
P.
Pousinis
,
D. A.
Barrett
,
B. E.
Scammell
,
V.
Chapman
.
2017
.
Targeting the D-series resolvin receptor system for the treatment of osteoarthritic pain.
Arthritis Rheumatol.
69
:
996
1008
.
7
Xu
,
Z.-Z.
,
L.
Zhang
,
T.
Liu
,
J.-Y.
Park
,
T.
Berta
,
R.
Yang
,
C. N.
Serhan
,
R.-R.
Ji
.
2010
.
Resolvins RvE1 and RvD1 attenuate inflammatory pain via central and peripheral actions.
Nat. Med.
16
:
592
597
, 1p following 597.
8
Serhan
,
C. N.
,
N.
Chiang
,
J.
Dalli
.
2017
.
New pro-resolving n-3 mediators bridge resolution of infectious inflammation to tissue regeneration.
Mol. Aspects Med.
DOI: 10.1016/j.mam.2017.1008.1002.
9
Mirakaj
,
V.
,
J.
Dalli
,
T.
Granja
,
P.
Rosenberger
,
C. N.
Serhan
.
2014
.
Vagus nerve controls resolution and pro-resolving mediators of inflammation.
J. Exp. Med.
211
:
1037
1048
.
10
Dalli
,
J.
,
R. A.
Colas
,
H.
Arnardottir
,
C. N.
Serhan
.
2017
.
Vagal regulation of group 3 innate lymphoid cells and the immunoresolvent PCTR1 controls infection resolution.
Immunity
46
:
92
105
.
11
Colas
,
R. A.
,
M.
Shinohara
,
J.
Dalli
,
N.
Chiang
,
C. N.
Serhan
.
2014
.
Identification and signature profiles for pro-resolving and inflammatory lipid mediators in human tissue.
Am. J. Physiol. Cell Physiol.
307
:
C39
C54
.
12
de la Rosa
,
X.
,
P. C.
Norris
,
N.
Chiang
,
A. R.
Rodriguez
,
B. W.
Spur
,
C. N.
Serhan
.
2018
.
Identification and complete stereochemical assignments of the new Resolvin Conjugates in Tissue Regeneration (RCTR) in human tissues that stimulate proresolving phagocyte functions and tissue regeneration.
Am. J. Pathol.
188
:
950
966
.
13
English
,
J. T.
,
P. C.
Norris
,
R. R.
Hodges
,
D. A.
Dartt
,
C. N.
Serhan
.
2017
.
Identification and profiling of specialized pro-resolving mediators in human tears by lipid mediator metabolomics.
Prostaglandins Leukot. Essent. Fatty Acids
117
:
17
27
.
14
Serhan
,
C. N.
,
J.
Dalli
,
R. A.
Colas
,
J. W.
Winkler
,
N.
Chiang
.
2015
.
Protectins and maresins: new pro-resolving families of mediators in acute inflammation and resolution bioactive metabolome.
Biochim. Biophys. Acta
1851
:
397
413
.
15
Asatryan
,
A.
,
N. G.
Bazan
.
2017
.
Molecular mechanisms of signaling via the docosanoid neuroprotectin D1 for cellular homeostasis and neuroprotection.
J. Biol. Chem.
292
:
12390
12397
.
16
Serhan
,
C. N.
,
G.
Fredman
,
R.
Yang
,
S.
Karamnov
,
L. S.
Belayev
,
N. G.
Bazan
,
M.
Zhu
,
J. W.
Winkler
,
N. A.
Petasis
.
2011
.
Novel proresolving aspirin-triggered DHA pathway.
Chem. Biol.
18
:
976
987
.
17
Lee
,
J. Y.
,
S. H.
Han
,
M. H.
Park
,
B.
Baek
,
I. S.
Song
,
M. K.
Choi
,
Y.
Takuwa
,
H.
Ryu
,
S. H.
Kim
,
X.
He
, et al
.
2018
.
Neuronal SphK1 acetylates COX2 and contributes to pathogenesis in a model of Alzheimer’s disease.
Nat. Commun.
9
:
1479
.
18
Lannan
,
K. L.
,
S. L.
Spinelli
,
N.
Blumberg
,
R. P.
Phipps
.
2017
.
Maresin 1 induces a novel pro-resolving phenotype in human platelets.
J. Thromb. Haemost.
15
:
802
813
.
19
Francos-Quijorna
,
I.
,
E.
Santos-Nogueira
,
K.
Gronert
,
A. B.
Sullivan
,
M. A.
Kopp
,
B.
Brommer
,
S.
David
,
J. M.
Schwab
,
R.
López-Vales
.
2017
.
Maresin 1 promotes inflammatory resolution, neuroprotection, and functional neurological recovery after spinal cord injury.
J. Neurosci.
37
:
11731
11743
.
20
Martini
,
A. C.
,
T.
Berta
,
S.
Forner
,
G.
Chen
,
A. F.
Bento
,
R. R.
Ji
,
G. A.
Rae
.
2016
.
Lipoxin A4 inhibits microglial activation and reduces neuroinflammation and neuropathic pain after spinal cord hemisection.
J. Neuroinflammation
13
:
75
.
21
Livne-Bar
,
I.
,
J.
Wei
,
H. H.
Liu
,
S.
Alqawlaq
,
G. J.
Won
,
A.
Tuccitto
,
K.
Gronert
,
J. G.
Flanagan
,
J. M.
Sivak
.
2017
.
Astrocyte-derived lipoxins A4 and B4 promote neuroprotection from acute and chronic injury.
J. Clin. Invest.
127
:
4403
4414
.
22
Winkler
,
J. W.
,
S.
Libreros
,
X.
De La Rosa
,
B. E.
Sansbury
,
P. C.
Norris
,
N.
Chiang
,
D.
Fichtner
,
G. S.
Keyes
,
N.
Wourms
,
M.
Spite
,
C. N.
Serhan
.
2018
.
Structural insights into Resolvin D4 actions and further metabolites via a new total organic synthesis and validation.
J. Leukoc. Biol.
103
:
995
1010
.
23
Samuelsson
,
B.
,
S. E.
Dahlén
,
J. A.
Lindgren
,
C. A.
Rouzer
,
C. N.
Serhan
.
1987
.
Leukotrienes and lipoxins: structures, biosynthesis, and biological effects.
Science
237
:
1171
1176
.
24
Le Maître
,
E.
,
P.
Revathikumar
,
H.
Idborg
,
J.
Raouf
,
M.
Korotkova
,
P. J.
Jakobsson
,
J.
Lampa
.
2015
.
Impaired vagus-mediated immunosuppression in microsomal prostaglandin E synthase-1 deficient mice.
Prostaglandins Other Lipid Mediat.
121
(
Pt B
):
155
162
.
25
Zanos
,
T. P.
,
H. A.
Silverman
,
T.
Levy
,
T.
Tsaava
,
E.
Battinelli
,
P. W.
Lorraine
,
J. M.
Ashe
,
S. S.
Chavan
,
K. J.
Tracey
,
C. E.
Bouton
.
2018
.
Identification of cytokine-specific sensory neural signals by decoding murine vagus nerve activity.
Proc. Natl. Acad. Sci. USA
115
:
E4843
E4852
.
26
Eckle
,
T.
,
K.
Brodsky
,
M.
Bonney
,
T.
Packard
,
J.
Han
,
C. H.
Borchers
,
T. J.
Mariani
,
D. J.
Kominsky
,
M.
Mittelbronn
,
H. K.
Eltzschig
.
2013
.
HIF1A reduces acute lung injury by optimizing carbohydrate metabolism in the alveolar epithelium.
PLoS Biol.
11
:
e1001665
.
27
Eckle
,
T.
,
E. M.
Kewley
,
K. S.
Brodsky
,
E.
Tak
,
S.
Bonney
,
M.
Gobel
,
D.
Anderson
,
L. E.
Glover
,
A. K.
Riegel
,
S. P.
Colgan
,
H. K.
Eltzschig
.
2014
.
Identification of hypoxia-inducible factor HIF-1A as transcriptional regulator of the A2B adenosine receptor during acute lung injury.
J. Immunol.
192
:
1249
1256
.
28
Neudecker
,
V.
,
M.
Haneklaus
,
O.
Jensen
,
L.
Khailova
,
J. C.
Masterson
,
H.
Tye
,
K.
Biette
,
P.
Jedlicka
,
K. S.
Brodsky
,
M. E.
Gerich
, et al
.
2017
.
Myeloid-derived miR-223 regulates intestinal inflammation via repression of the NLRP3 inflammasome.
J. Exp. Med.
214
:
1737
1752
.
29
Koopman
,
F. A.
,
S. S.
Chavan
,
S.
Miljko
,
S.
Grazio
,
S.
Sokolovic
,
P. R.
Schuurman
,
A. D.
Mehta
,
Y. A.
Levine
,
M.
Faltys
,
R.
Zitnik
, et al
.
2016
.
Vagus nerve stimulation inhibits cytokine production and attenuates disease severity in rheumatoid arthritis.
Proc. Natl. Acad. Sci. USA
113
:
8284
8289
.
30
Spitzer
,
M. H.
,
P. F.
Gherardini
,
G. K.
Fragiadakis
,
N.
Bhattacharya
,
R. T.
Yuan
,
A. N.
Hotson
,
R.
Finck
,
Y.
Carmi
,
E. R.
Zunder
,
W. J.
Fantl
, et al
.
2015
.
IMMUNOLOGY. An interactive reference framework for modeling a dynamic immune system.
Science
349
:
1259425
.

The authors have no financial conflicts of interest.

Supplementary data