A major family of Specialized pro-resolving mediators (SPMs) biosynthesized from Omega-3 fatty acids (EPA and DHA) that actively terminate inflammation and orchestrate tissue repair. E-series resolvins (RvE1-3) derive from EPA via 5-LOX pathways; D-series resolvins (RvD1-6) arise from DHA via 15-LOX. Unlike passive inflammation decay, resolvins are active "stop signals" that halt neutrophil recruitment, promote Efferocytosis, shift macrophages to M2 phenotype, and protect organs from collateral damage during inflammatory resolution.
Imagine inflammation as a house fire: you need firefighters (neutrophils) to extinguish the flames, but once the fire's out, you don't want them smashing through walls indefinitely. Resolvins are the fire chief who radios "all-clear" and sends the crew home, while simultaneously calling in the renovation team (M2 macrophages) to rebuild. The chief doesn't just yell "stop"βthey hand out specific instructions: firefighters stop arriving (anti-chemotaxis), the ones already there finish their shift without causing extra damage (reduced reactive oxygen species), and the debris crew starts hauling away charred beams (Efferocytosis of dead cells). Meanwhile, specialized repair workers (fibroblasts, epithelial cells) receive growth signals to patch the roof and repaint the walls. Without resolvins (the fire chief), you'd have firefighters wandering aimlessly, continuing to spray water long after the blaze is outβthis is chronic inflammation. The E-series chief (from EPA) particularly focuses on the gut and bones, while the D-series chief (from DHA) oversees liver, kidney, lung, and brain renovations.
E-series (from EPA):
- EPA β 5-LOX β 5-hydroperoxy-EPA β RvE1, RvE2, RvE3
- Alternatively: EPA β aspirin-acetylated COX-2 β 18R-HEPE β 5-LOX β aspirin-triggered RvE (AT-RvE)
D-series (from DHA):
- DHA β 15-LOX β 17-hydroperoxy-DHA β RvD1-6
- Alternatively: DHA β aspirin-acetylated COX-2 β 17R-HDHA β 5-LOX β aspirin-triggered RvD (AT-RvD1)
ΒΆ Receptor Signaling and Downstream Effects
RvE series:
- RvE1 binds ERV1/ChemR23 β GΞ±i-protein-coupled signaling β β cAMP β β NF-ΞΊB β β IL-1Ξ², β TNF-Ξ±
- RvE1 also binds LGR6 (leucine-rich repeat-containing G protein-coupled receptor 6) β β phagocytosis
- Blocks LTB4 (leukotriene B4) receptor β prevents neutrophil chemotaxis
RvD series:
- RvD1 binds GPR32 (DRV1) and ALX/FPR2 β β neutrophil infiltration, β macrophage phagocytic capacity
- RvD2 binds GPR18 (DRV2) β β bacterial phagocytosis, β inflammatory cytokines
- RvD3-6 via similar GPCRs β organ-specific protective effects
Shared downstream cascades:
- β M2 macrophages polarization via SOCS3 and SOCS1 β IL-10 secretion
- β Efferocytosis: phosphatidylserine recognition β opsonization of apoptotic neutrophils β debris clearance
- β NF-ΞΊB nuclear translocation β β COX-2, β iNOS transcription
- β neutrophil transendothelial migration via β selectin/integrin adhesion
- β antimicrobial peptides (AMPs) without amplifying inflammation
- β NLRP3 inflammasome activation β β IL-1Ξ² maturation
graph TD
EPA[EPA] -->|5-LOX| RvE[RvE1-3]
DHA[DHA] -->|15-LOX| RvD[RvD1-6]
EPA -->|Aspirin-acetylated COX-2| ATRvE[AT-RvE]
DHA -->|Aspirin-acetylated COX-2| ATRvD[AT-RvD1]
RvE -->|ERV1/ChemR23| E_sig["β NF-ΞΊB, β cAMP"]
RvD -->|GPR32, ALX/FPR2| D_sig["β Neutrophil trafficking"]
E_sig --> Stop[Stop Signals]
D_sig --> Stop
Stop --> N1["β Neutrophil recruitment"]
Stop --> N2["β IL-1Ξ², TNF-Ξ±, IL-6"]
Stop --> M["β M2 Macrophage polarization"]
Stop --> E["β Efferocytosis"]
M --> Repair[Tissue Repair]
E --> Repair
Repair --> Heal["Resolution complete: homeostasis restored"]
- RvE series: GI barrier integrity (β tight junctions), bone protection (β osteoclast activity), airway homeostasis
- RvD series:
- RvD1: hepatoprotection (β hepatic steatosis, β fibrosis), renal protection (β ischemia-reperfusion injury)
- RvD2-6: lung (β ARDS severity), neuroprotection (β microglial activation, β neurogenesis)
Resolvins represent the shift from viewing inflammation as a binary on/off switch to understanding it as a biphasic process requiring active molecular termination. In cPNI practice, inadequate resolvin synthesis is a key mechanism underlying chronic inflammation, chronic pain, and metabolic dysfunction.
Conditions where resolvin deficiency is implicated:
Metamodel connections:
- Metamodel 1 (Evolutionary mismatch): Modern Western diets (omega-6/omega-3 ratio >15:1) lack EPA/DHA precursors, creating "resolution insufficiency syndrome"
- Metamodel 3 (Selfish Brain): Chronic cortisol elevation suppresses 15-LOX activity β β RvD synthesis β impaired immune resolution favoring brain glucose access
- Selfish Immune System: Unresolved inflammation diverts energy to perpetual immune activation, starving muscle/metabolism
Clinical thresholds and biomarkers:
- Omega-3 index <4% indicates insufficient resolvin precursor availability (target >8%)
- Plasma RvE1 <50 pg/mL associated with active IBD (reference >100 pg/mL in remission)
- Neutrophil-to-lymphocyte ratio >3.0 suggests impaired resolution of inflammation
Intervention implications:
- Nutritional: EPA 2-4 g/day, DHA 1-2 g/day to restore SPM biosynthesis capacity
- Aspirin low-dose (81 mg): triggers COX-2 acetylation β aspirin-triggered resolvins (AT-RvE, AT-RvD1)
- Lifestyle: Exercise β 15-LOX expression; chronic stress β LOX enzyme activity
- Avoid: NSAIDs (except aspirin) block COX-2 without triggering acetylation β impair SPM class switching
- Therapeutic SPMs: Emerging RvE1 analogs in clinical trials for dry eye disease, periodontal disease
- RvE1 has EC50 ~1 nM for neutrophil chemotaxis inhibition (picomolar potency)
- RvD1 reduces neutrophil infiltration by 40-60% in peritonitis models within 4 hours
- Aspirin (75-325 mg/day) increases AT-RvD1 production 2-3-fold via COX-2 acetylation
- RvE1 protects against bone loss by inhibiting osteoclastogenesis (β RANKL signaling)
- RvD2 accelerates wound healing by 30-50% in diabetic ulcer models
- Omega-3 fatty acids must be present as free acids (not ethyl esters) for optimal resolvin synthesis
- RvE series production peaks 6-12 hours post-inflammation onset; RvD series at 12-24 hours
- Resolvins reduce pain independently of COX inhibitionβvia TRP channel desensitization and spinal sensitization reversal
- Dietary EPA:DHA ratio of 2:1 optimizes both RvE and RvD synthesis
- RvD1 enhances macrophage phagocytosis of bacteria (E. coli, S. aureus) without amplifying cytokine releaseβ"eat without shouting"
- Specialized pro-resolving mediators (SPMs) β resolvins are the largest and most-studied SPM family
- EPA β direct biosynthetic precursor for E-series resolvins
- DHA β direct biosynthetic precursor for D-series resolvins
- Omega-3 fatty acids β dietary source; tissue membrane incorporation necessary for resolvin synthesis
- 5-LOX β key enzyme converting EPA to RvE series
- 15-LOX β key enzyme converting DHA to RvD series
- COX-2 acetylation β aspirin mechanism producing aspirin-triggered resolvins (AT-RvE, AT-RvD1)
- Lipoxins (LX) β earlier SPM family from arachidonic acid; resolvins amplify lipoxin signaling
- Protectins β parallel DHA-derived SPM family with overlapping anti-inflammatory effects
- Maresins β macrophage-derived SPMs from DHA; coordinate with resolvins in tissue repair
- Efferocytosis β resolvins upregulate "eat-me" signal recognition on apoptotic cells
- M2 macrophages β resolvins drive M1βM2 polarization via SOCS3 and IL-10 induction
- neutrophils β resolvins halt recruitment and promote apoptosis without necrosis
- NF-ΞΊB β resolvins suppress nuclear translocation, blocking inflammatory gene transcription
- chronic inflammation β results from inadequate resolvin production or receptor desensitization
- resolution of inflammation β resolvins are the primary molecular orchestrators of this active process
- Eicosanoid switch β transition from pro-inflammatory Prostaglandins/leukotrienes to pro-resolving resolvins
- ALX/FPR2 receptor β shared receptor for lipoxins and RvD1; crosstalk between SPM families
- neuroprotection β RvD series reduce microglial activation and neuroinflammation in Alzheimer's/Parkinson's
- Inflammatory bowel disease β mucosal resolvin deficiency perpetuates IBD; RvE1 analogs in trials
- wound healing β resolvins accelerate granulation tissue formation and re-epithelialization
- chronic pain β resolvins block spinal sensitization and peripheral nociceptor hyperexcitability
- insulin resistance β adipose tissue resolvin deficiency sustains metaflammation
- Omega-3 index β biomarker of resolvin biosynthetic capacity (target >8%)
- SOCS1 β resolvin-induced suppressor of cytokine signaling; terminates inflammatory loops
- Low-Grade Inflammation β subclinical resolvin insufficiency allows persistent cytokine elevation
- Module 1 β Evolutionary context: Carnivore connection, FADS2 enzyme bottleneck limiting omega-3 conversion
- Module 4 β Immune resolution mechanisms, SPM biosynthesis pathways
- Module 5 β Clinical applications in chronic inflammatory conditions, resolution pharmacology