Herring roe oil supplementation alters microglial cell gene expression and reduces peripheral inflammation after immune activation in a neonatal piglet model.

Neonatal brain development can be disrupted by infection that results in microglial cell activation and neuroinflammation. Studies indicate that polyunsaturated fatty acids (PUFAs) and their metabolites can resolve inflammation. It is not known if dietary PUFA increases lipid metabolites in brain or reduces neuroinflammation in neonates. We hypothesized that dietary PUFAs might suppress neuroinflammation by inhibiting pro-inflammatory cytokine over-production and promoting inflammatory resolution in the periphery and brain. Piglets were obtained on postnatal day (PD) 2 and randomly assigned to herring roe oil (HRO) or control (CON) diet. HRO was included at 2 g/kg powdered diet. HRO increased DHA levels in occipital lobe and the DHA to arachidonic acid (ARA) ratio in hippocampal tissue. HRO decreased ARA metabolites in occipital lobe. HRO failed to attenuate microglial pro-inflammatory cytokine production ex vivo. HRO did not affect fever or circulating resolvin D1 levels. HRO decreased circulating neutrophils and liver inflammatory gene expression, but increased resolution marker gene expression in liver post LPS. HRO upregulated CXCL16, TGFBR1, and C1QA in microglial cells. HRO supplementation exerted beneficial effects on inflammation in the periphery, but further studies are needed to evaluate the specific effects of omega-3 supplementation on microglial cell physiology in the neonate.

Emerging class of omega-3 fatty acid endocannabinoids & their derivatives.

Cannabinoid receptor activation is involved in homeostatic regulation of the body. These receptors are activated by cannabinoids, that include the active constituents of Cannabis sativa, as well as endocannabinoids (eCBs). The eCBs are endogenously synthesized from the omega-6 and omega-3 polyunsaturated fatty acids (PUFAs). The consumption of omega-3 fatty acids shifts the balance towards a higher proportion of omega-3 eCBs, whose physiological functions warrants further investigation. Herein, we review the discovery of omega-3 fatty acid derived eCBs that are generated from long chain omega-3 PUFAs - docosahexaenoyl ethanolamide (DHA-EA or synaptamide), docosahexanoyl-glycerol (DHG), eicosapentaenoyl ethanolamide (EPA-EA) and eicosapentanoylglycerol (EPG). Furthermore, we outline the lesser known omega-3 eCB-like molecules that arise from the conjugation of omega-3 fatty acids with neurotransmitters serotonin and dopamine - DHA-serotonin (DHA-5HT), DHA-dopamine (DHA-DA), EPA-serotonin (EPA-5HT) and EPA-dopamine (EPA-DA). Additionally, we describe the role of omega-3 eCBs and their derivatives in different disease states, such as pain, inflammation and cancer. Moreover, we detail the formation and potential physiological roles of the oxidative metabolites that arise from the metabolism of omega-3 eCBs by eicosanoid synthesizing enzymes - cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 epoxygenase (CYP450). In summary, we outline the novel findings regarding a growing class of signaling molecules that can control the physiological and pathophysiological processes in the body.

Antitumorigenic Properties of Omega-3 Endocannabinoid Epoxides.

Accumulating studies have linked inflammation to tumor progression. Dietary omega-3 fatty acids, such as docosahexaenoic acid (DHA), have been shown to suppress tumor growth through their conversion to epoxide metabolites. Alternatively, DHA is converted enzymatically into docosahexaenoylethanolamide (DHEA), an endocannabinoid with antiproliferative activity. Recently, we reported a novel class of anti-inflammatory DHEA-epoxide derivative called epoxydocospentaenoic-ethanolamide (EDP-EA) that contain both ethanolamide and epoxide moieties. Herein, we study the antitumorigenic properties of EDP-EAs in an osteosarcoma (OS) model. First, we show ∼80% increase in EDP-EAs in metastatic versus normal lungs of mice. We found significant differences in the apoptotic and antimigratory potencies of the different EDP-EA regioisomers, which were partially mediated through cannabinoid receptor 1 (CB1). Next, we synthesized derivatives of the most pro-apoptotic regioisomer. These derivatives had reduced hydrolytic susceptibility to fatty acid amide hydrolase (FAAH) and increased CB1-selective binding. Collectively, we report a novel class of EDP-EAs that exhibit antiangiogenic, antitumorigenic, and antimigratory properties in OS.

Anti-inflammatory ω-3 endocannabinoid epoxides.

Clinical studies suggest that diets rich in ω-3 polyunsaturated fatty acids (PUFAs) provide beneficial anti-inflammatory effects, in part through their conversion to bioactive metabolites. Here we report on the endogenous production of a previously unknown class of ω-3 PUFA-derived lipid metabolites that originate from the crosstalk between endocannabinoid and cytochrome P450 (CYP) epoxygenase metabolic pathways. The ω-3 endocannabinoid epoxides are derived from docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) to form epoxyeicosatetraenoic acid-ethanolamide (EEQ-EA) and epoxydocosapentaenoic acid-ethanolamide (EDP-EA), respectively. Both EEQ-EAs and EDP-EAs are endogenously present in rat brain and peripheral organs as determined via targeted lipidomics methods. These metabolites were directly produced by direct epoxygenation of the ω-3 endocannabinoids, docosahexanoyl ethanolamide (DHEA) and eicosapentaenoyl ethanolamide (EPEA) by activated BV-2 microglial cells, and by human CYP2J2. Neuroinflammation studies revealed that the terminal epoxides 17,18-EEQ-EA and 19,20-EDP-EA dose-dependently abated proinflammatory IL-6 cytokines while increasing anti-inflammatory IL-10 cytokines, in part through cannabinoid receptor-2 activation. Furthermore the ω-3 endocannabinoid epoxides 17,18-EEQ-EA and 19,20-EDP-EA exerted antiangiogenic effects in human microvascular endothelial cells (HMVEC) and vasodilatory actions on bovine coronary arteries and reciprocally regulated platelet aggregation in washed human platelets. Taken together, the ω-3 endocannabinoid epoxides' physiological effects are mediated through both endocannabinoid and epoxyeicosanoid signaling pathways. In summary, the ω-3 endocannabinoid epoxides are found at concentrations comparable to those of other endocannabinoids and are expected to play critical roles during inflammation in vivo; thus their identification may aid in the development of therapeutics for neuroinflammatory and cerebrovascular diseases.