Activation of microglia contributes to the pathogenesis of central neuropathic pain (CNP), yet effective treatments remain limited. Docosahexaenoyl-ethanolamine (DHEA) and eicosapentaenoyl-ethanolamine (EPEA) are omega-3-derived ethanolamides with reported immunoregulatory and neuroprotective actions. We examined the effects of DHEA and EPEA, alone and in combination, on microglial activation, microglia-neuron crosstalk, and cannabinoid receptor-associated signalling. In LPS-activated microglia, DHEA and EPEA reduced pro-inflammatory mediator expression, attenuated inflammatory cytokine and chemokine profiles, and increased anti-inflammatory mediators including BMP7. Conditioned medium from activated microglia induced neuronal stress, whereas conditioned medium from DHEA-treated microglia, as well as BMP7 alone, attenuated this effect. DHEA and EPEA promoted via CB1R- and CB2R-dependent Gαi and β-arrestin interaction, receptor internalisation, ERK activation, and reduced cAMP accumulation. Together, these findings show that DHEA and EPEA suppress microglial inflammatory signalling and reduce microglia-induced neuronal stress, support a role for CBR-receptor signalling in their actions and provide evidence for their therapeutic potential in central neuropathic pain.

Circadian rhythms are biological rhythms that originate from the “master circadian clock,” called the suprachiasmatic nucleus (SCN). SCN orchestrates the circadian rhythms using light as a chief zeitgeber, enabling humans to synchronize their daily physio-behavioral activities with the Earth’s light-dark cycle. However, chronic/ irregular photic disturbances from the retina via the retinohypothalamic tract (RHT) can disrupt the amplitude and the expression of clock genes, such as the period circadian clock 2, causing circadian rhythm disruption (CRd) and associated neuropathologies. The present review discusses neuromodulation across the RHT originating from retinal photic inputs and modulation offered by endocannabinoids as a function of mitigation of the CRd and associated neuro-dysfunction. Literature indicates that cannabinoid agonists alleviate the SCN’s ability to get entrained to light by modulating the activity of its chief neurotransmitter, i.e., γ-aminobutyric acid, thus preventing light-induced disruption of activity rhythms in laboratory animals. In the retina, endocannabinoid signaling modulates the overall gain of the retinal ganglion cells by regulating the membrane currents (Ca2+, K+, and Cl- channels) and glutamatergic neurotransmission of photoreceptors and bipolar cells. Additionally, endocannabinoids signalling also regulate the high-voltage-activated Ca2+ channels to mitigate the retinal ganglion cells and intrinsically photosensitive retinal ganglion cells-mediated glutamate release in the SCN, thus regulating the RHT-mediated light stimulation of SCN neurons to prevent excitotoxicity. As per the literature, cannabinoid receptors 1 and 2 are becoming newer targets in drug discovery paradigms, and the involvement of endocannabinoids in light-induced CRd through the RHT may possibly mitigate severe neuropathologies.

Approximately 1 in 4 people worldwide have non-alcoholic fatty liver disease (NAFLD); however, there are currently no medications to treat this condition. This study investigated the role of adiposity-associated orphan G protein-coupled receptor 75 (GPR75) in liver lipid accumulation. We profiled Gpr75 expression and report that it is most abundant in the brain. Next, we generated the first single-cell-level analysis of Gpr75 and identified a subpopulation co-expressed with key appetite-regulating hypothalamic neurons. CRISPR-Cas9-deleted Gpr75 mice fed a palatable western diet high in fat adjusted caloric intake to remain in energy balance, thereby preventing NAFLD. Consistent with mouse results, analysis of whole-exome sequencing data from 428,719 individuals (UK Biobank) revealed that variants in GPR75 are associated with a reduced likelihood of hepatic steatosis. Here, we provide a significant advance in understanding of the expression and function of GPR75, demonstrating that it is a promising pharmaceutical target for NAFLD treatment.

G protein-coupled receptors (GPCRs) with no known endogenous ligand are termed orphans. Deorphanization of a GPCR involves identifying the ligand, which can be a painstaking exercise. In this Comment, we discuss the challenges in the process, its role in drug discovery and alternative approaches to characterizing orphan GPCRs.

Aortic valve stenosis is the most common valve disease in the western world. Central to the pathogenesis of this disease is the growth of new blood vessels (angiogenesis) within the aortic valve allowing infiltration of immune cells and development of intra-valve inflammation. Identifying the cellular mediators involved in this angiogenesis is important as this may reveal new therapeutic targets which could ultimately prevent the progression of aortic valve stenosis. Aortic valves from patients undergoing surgery for aortic valve replacement or dilation of the aortic arch were examined both ex vivo and in vitro. We now demonstrate that the anti-angiogenic protein, soluble fms-like tyrosine kinase 1 (sFlt1), a non-signalling soluble receptor for vascular endothelial growth factor, is constitutively expressed in non-diseased valves. sFlt-1 expression was, however, significantly reduced in aortic valve tissue from patients with aortic valve stenosis while protein markers of hypoxia were simultaneously increased. Exposure of primary-cultured valve interstitial cells to hypoxia resulted in a decrease in the expression of sFlt-1. We further reveal using a bioassay that siRNA knock-down of sFlt1 in valve interstitial cells directly results in a pro-angiogenic environment. Finally, incubation of aortic valves with sphingosine 1-phosphate, a bioactive lipid-mediator, increased sFlt-1 expression and inhibited angiogenesis within valve tissue. In conclusion, this study demonstrates that sFlt1 expression is directly correlated with angiogenesis in aortic valves and the observed decrease in sFlt-1 expression in aortic valve stenosis could increase valve inflammation, promoting disease progression. This could be a viable therapeutic target in treating this disease.

Background The association between systemic hypertension and cerebrovascular disease is well documented. However, the impact of pulmonary hypertension (PH) on acute ischemic stroke outcomes is unknown despite PH being recognized as a risk factor for acute ischemic stroke. We aimed to determine the association between PH and adverse in‐hospital outcomes after acute ischemic stroke, as well as whether there are sex differences in this association. Methods and Results Acute ischemic stroke admissions from the US National Inpatient Sample between October 2015 and December 2017 were included. The relationship between PH and outcomes (mortality, prolonged hospitalization >4 days, and routine home discharge) was analyzed using logistic regressions adjusting for demographics, comorbidities, and revascularization therapies. Interaction terms between PH and sex and age groups were also included. A total of 221 249 records representative of 1 106 045 admissions were included; 2.9% of patients had co‐morbid PH, and 35.34% of those were male. PH was not associated with in‐hospital mortality (odds ratio [OR], 0.96; 95% CI, 0.86–1.09) but was associated with increased odds of prolonged hospitalization (OR, 1.15; 95% CI, 1.09–1.22) and decreased odds of routine discharge (OR, 0.87; 95% CI, 0.81–0.94) for both sexes. Older patients with PH were significantly less likely to be discharged routinely (P=0.028) than their younger counterparts. Compared with female patients with PH, men were 31% more likely to die in hospital (P=0.024). Conclusions PH was not significantly associated with in‐hospital mortality but was associated with prolonged hospitalization and adverse discharge status. Male patients with PH were more likely to die in hospital than female patients.

sampled from control coronary arteries and from advanced coronary atherosclerotic plaques. Methods and Results A protocol was optimised to perform laser capture microdissection for isolation of endothelium in under 20 minutes, from snap-frozen porcine coronary artery cross-sections for total RNA sequencing (n=5 D374Y-PCSK9 hyperlipidaemic minipigs fed on a high fat high cholesterol diet; 10 vessels). Endothelium was sampled from control left anterior descending arteries consisting of no plaque, and from overlying advanced atherosclerotic plaque in stenotic right coronary arteries. Differential gene expression and gene ontology enrichment analyses revealed the upregulation of numerous atheroprone inflammatory genes in diseased endothelium overlying atherosclerotic plaque compared to healthy endothelium (figure 1: p<0.01, FDR<0.05, fold change >2). Biological pathways related to atherosclerosis that the differentially expressed genes are most enriched in are shown (table 1: enrichment score >3). Conclusions We report in vivo changes in gene expression in diseased endothelium overlying advanced coronary atherosclerotic plaques, with upregulation of inflammatory genes. The differentially expressed genes are enriched in processes related to atherosclerosis, suggesting the validity of this approach to study how gene expression changes during coronary atherosclerotic plaque development in vivo. Our model system allows for further studies coupling together these readouts to a fully validated 3D vessel reconstruction method to co-register gene expression profiles to local blood flow data, as a novel methodology for understanding the mechanisms by which local flow disturbances may affect atherogenesis. This will provide new insights into how disturbed flow and coronary atherosclerotic plaque development are causally related. Conflict of Interest None