Sickness behaviour is an adaptive behavioural response to the activation of the innate immune system. It is mediated by brain cytokine production and action, especially interleukin-6 (IL-6). Polyunsaturated fatty acids (PUFA) are essential fatty acids that are highly incorporated in brain cells membranes and display immunomodulating properties. We hypothesized that a decrease in n-3 PUFA brain level by dietary means impacts on lipopolysaccharide (LPS)-induced IL-6 production and sickness behaviour. Our results show that mice exposed throughout life to a diet containing n-3 PUFA (n-3/n-6 diet) display a decrease in social interaction that does not occur in mice submitted to a diet devoid of n-3 PUFA (n-6 diet). LPS induced high IL-6 plasma levels as well as expression of IL-6 mRNA in the hippocampus and cFos mRNA in the brainstem of mice fed either diet, indicating intact immune-to-brain communication. However, STAT3 and STAT1 activation, a hallmark of IL-6 signalling pathway, was lower in the hippocampus of LPS-treated n-6 mice as compared to n-3/n-6 mice. In addition, LPS did not reduce social interaction in IL-6 knock-out (IL-6 KO) mice and failed to induce STAT3 activation in the brain of IL-6 KO mice. Altogether, these findings point to alteration in brain STAT3 as a key mechanism for the lack of effect of LPS on social interaction in mice fed with the n-6 PUFA diet. The relative deficiency of Western diets in n-3 PUFA could impact on behavioural aspects of the host response to infection.

The P2X 7 receptor (P2X 7 R) is a purinoceptor expressed predominantly by cells of immune origin, including microglial cells. P2X 7 R has a role in the release of biologically active proinflammatory cytokines such as IL-1β, IL-6 and TNFα. Here we demonstrate that when incubated with lipopolysaccharide (LPS), glial cells cultured from brain of P2X 7 R −/− mice produce less IL-1β compared to glial cells from brains of wild-type mice. This is not the case for TNFα and IL-6. Our results indicate a selective effect of the P2X7R gene deletion on release of IL-1β release but not of IL-6 and TNFα. In addition, we confirm that only microglial cells produce IL-1β, and this release is dependent on P2X 7 R and ABC1 transporter. Because IL-1β is a key regulator of the brain cytokine network and P2X 7 R is an absolute requirement for IL-1β release, we further investigated whether response of brain cytokines to LPS in vivo was altered in P2X 7 R −/− mice compared to wild-type mice. IL-1β and TNFα mRNAs were less elevated in the brain of P2X 7 R −/− than in the brain of wild-type mice in response to systemic LPS. These results show that P2X7R plays a key role in the brain cytokine response to immune stimuli, which certainly applies also to cytokinedependent alterations in brain functions including sickness behavior.

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Background Clinical complexity is increasingly prevalent among patients with atrial fibrillation (AF). The ‘Atrial fibrillation Better Care’ (ABC) pathway approach has been proposed to streamline a more holistic and integrated approach to AF care; however, there are limited data on its usefulness among clinically complex patients. We aim to determine the impact of ABC pathway in a contemporary cohort of clinically complex AF patients. Methods From the ESC-EHRA EORP-AF General Long-Term Registry, we analysed clinically complex AF patients, defined as the presence of frailty, multimorbidity and/or polypharmacy. A K-medoids cluster analysis was performed to identify different groups of clinical complexity. The impact of an ABC-adherent approach on major outcomes was analysed through Cox-regression analyses and delay of event (DoE) analyses. Results Among 9966 AF patients included, 8289 (83.1%) were clinically complex. Adherence to the ABC pathway in the clinically complex group reduced the risk of all-cause death (adjusted HR [aHR]: 0.72, 95%CI 0.58–0.91), major adverse cardiovascular events (MACEs; aHR: 0.68, 95%CI 0.52–0.87) and composite outcome (aHR: 0.70, 95%CI: 0.58–0.85). Adherence to the ABC pathway was associated with a significant reduction in the risk of death (aHR: 0.74, 95%CI 0.56–0.98) and composite outcome (aHR: 0.76, 95%CI 0.60–0.96) also in the high-complexity cluster; similar trends were observed for MACEs. In DoE analyses, an ABC-adherent approach resulted in significant gains in event-free survival for all the outcomes investigated in clinically complex patients. Based on absolute risk reduction at 1 year of follow-up, the number needed to treat for ABC pathway adherence was 24 for all-cause death, 31 for MACEs and 20 for the composite outcome. Conclusions An ABC-adherent approach reduces the risk of major outcomes in clinically complex AF patients. Ensuring adherence to the ABC pathway is essential to improve clinical outcomes among clinically complex AF patients.

Aims The 4S-AF classification scheme comprises of four domains: stroke risk (St), symptoms (Sy), severity of atrial fibrillation (AF) burden (Sb), and substrate (Su). We sought to examine the implementation of the 4S-AF scheme in the EORP-AF General Long-Term Registry and compare outcomes in AF patients according to the 4S-AF-led decision-making process. Methods and results  Atrial fibrillation patients from 250 centres across 27 European countries were included. A 4S-AF score was calculated as the sum of each domain with a maximum score of 9. Of 6321 patients, 8.4% had low (St), 47.5% EHRA I (Sy), 40.5% newly diagnosed or paroxysmal AF (Sb), and 5.1% no cardiovascular risk factors or left atrial enlargement (Su). Median follow-up was 24 months. Using multivariable Cox regression analysis, independent predictors of all-cause mortality were (St) [adjusted hazard ratio (aHR) 8.21, 95% confidence interval (CI): 2.60–25.9], (Sb) (aHR 1.21, 95% CI: 1.08–1.35), and (Su) (aHR 1.27, 95% CI: 1.14–1.41). For CV mortality and any thromboembolic event, only (Su) (aHR 1.73, 95% CI: 1.45–2.06) and (Sy) (aHR 1.29, 95% CI: 1.00–1.66) were statistically significant, respectively. None of the domains were independently linked to ischaemic stroke or major bleeding. Higher 4S-AF score was related to a significant increase in all-cause mortality, CV mortality, any thromboembolic event, and ischaemic stroke but not major bleeding. Treatment of all 4S-AF domains was associated with an independent decrease in all-cause mortality (aHR 0.71, 95% CI: 0.55–0.92). For each 4S-AF domain left untreated, the risk of all-cause mortality increased substantially (aHR 1.35, 95% CI: 1.16–1.56). Conclusion  Implementation of the novel 4S-AF scheme is feasible, and treatment decisions based on this scheme improve mortality rates in AF.