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This surveillance study described a cohort of adults and children with neurological manifestations of influenza. The majority were due to H1N1. More children than adults were identified; many children had specific encephalopathy syndromes with poor outcomes. None had been vaccinated, although 8 (32%) had indications for this. A modified classification system is proposed based on our data and the increasing spectrum of recognized acute encephalopathy syndromes.

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Cholestane-3β,5α,6β-triol (3β,5α,6β-triol) is formed from cholestan-5,6-epoxide (5,6-EC) in a reaction catalysed by cholesterol epoxide hydrolase, following formation of 5,6-EC through free radical oxidation of cholesterol. 7-Oxocholesterol (7-OC) and 7β-hydroxycholesterol (7β-HC) can also be formed by free radical oxidation of cholesterol. Here we investigate how 3β,5α,6β-triol, 7-OC and 7β-HC are metabolised to bile acids. We show, by monitoring oxysterol metabolites in plasma samples rich in 3β,5α,6β-triol, 7-OC and 7β-HC, that these three oxysterols fall into novel branches of the acidic pathway of bile acid biosynthesis becoming (25R)26-hydroxylated then carboxylated, 24-hydroxylated and side-chain shortened to give the final products 3β,5α,6β-trihydroxycholanoic, 3β-hydroxy-7-oxochol-5-enoic and 3β,7β-dihydroxychol-5-enoic acids, respectively. The intermediates in these pathways may be causative of some phenotypical features of, and/or have diagnostic value for, the lysosomal storage diseases, Niemann Pick types C and B and lysosomal acid lipase deficiency. Free radical derived oxysterols are metabolised in human to unusual bile acids via novel branches of the acidic pathway, intermediates in these pathways are observed in plasma.

Introduction In recent years an increasing range of neurological syndromes has been associated with the emergence of novel influenza A:H1N1 (2009), and other influenza viruses. We aimed to describe the features of adults and children with neurological manifestations associated with influenza in the UK. Method A surveillance study was performed in conjunction with the BNSU and BPNSU* over a 24–month period (February 2011 to February 2013). Inclusion criteria specified acute neurological illness within 1 month of proven influenza infection and prospective case definitions were applied. Results Twenty–five cases were identified: 4 adults and 21 children [6 (23%) with pre–existing neurological disorders]. Four (16%) cases (all with encephalopathy syndromes) died. Twenty cases (80%) required admission to intensive care. Seventeen (68%) had Glasgow Outcome Scores of 2–5 indicating poor outcome. Polymerase chain reaction (PCR) of respiratory secretions identified: influenza A in 21 (20 H1N1) and influenza B in 4 cases. Two had co–infection with Streptococcus pneumoniae (one adult with septicaemia; one child with meningitis). Cerebrospinal fluid (CSF) revealed a pleocytosis in 3 out of 18 cases (median 184×106 cells/litre [range 16–900]). Influenza PCR was negative in all 10 CSF samples tested. Cerebral magnetic resonance imaging was performed in 3 cases, computerised tomography in 6, and 14 had both. Recognised acute encephalopathy syndromes were seen in 5, and non–specific changes including cerebral oedema and/or diffusion restriction in 5. For the 4 adults, 2 presented with acute extrapyramidal movement disorders, 1 with Guillain–Barré syndrome and 1 with acute encephalopathy. Of the 21 children, 17 presented with acute encephalopathy, 3 with encephalitis and 1 with acute dyskinesia. Encephalopathy syndromes were documented in 7 cases (6 children, 1 adult). They were characterised by their clinical presentation and neuroimaging and included 4 with Acute Necrotising Encephalopathy (ANE), 1 Acute Infantile Encephalopathy Predominantly Affecting the Frontal Lobes (AIEF), 1 Haemorrhagic Shock & Encephalopathy (HSE) syndrome and 1 Acute Haemorrhagic Leukoencephalopathy (AHL). Treatments included: systemic steroids in 4 cases, 1 had intravenous immunoglobulin, and 3 cases received both. None received plasma exchange. Influenza vaccination was indicated in eight cases, but none had received it. Conclusion This paediatric and adult UK cohort identified a severity of influenza related neurological manifestation not reported previously. Cases were more common in children, particularly those with underlying neurological conditions. Encephalopathy syndromes such as ANE, AIEF, HSE and AHL were seen more frequently in children and were associated with a worse outcome. Acute movement disorders and Guillain–Barré syndrome were identified more commonly in adults. Influenza related encephalopathy may be more common in those with abnormal genetically determined host inflammatory responses, but the virus itself is rarely detected in ...

Severe COVID-19 appears rare in children. This is unexpected, especially in young infants, who are vulnerable to severe disease caused by other respiratory viruses. We evaluate convalescent immune responses in four infants under 3 months old with confirmed COVID-19 who presented with mild febrile illness, alongside their parents, and adult controls recovered from confirmed COVID-19. Although not statistically significant, compared to seropositive adults, infants have high serum levels of IgG and IgA to SARS-CoV-2 spike protein with corresponding functional ability to block SARS-CoV-2 cellular entry. Infants also exhibit robust saliva anti-spike IgG and IgA responses. Spike-specific IFN-γ production by infant peripheral blood mononuclear cells appears restrained, but the frequency of spike-specific IFN-γ and/or TNF-ɑ producing T cells is comparable between infants and adults. On principal component analysis, infant immune responses appear distinct from their parents. Robust functional antibody responses alongside restrained IFN-γ production may help protect infants from severe COVID-19.

The requirement to remove apoptotic cells is equally important in homeostasis and inflammatory disease. In particular, during viral infections large quantities of infected cells undergo apoptosis and need to be efficiently cleared by phagocytes to prevent secondary necrosis. Although specific roles of several apoptotic cell sensors, such as the TAM (Tyro3, Axl, MerTK) receptor family, have been characterized in mouse models, little is known about their regulation and involvement in apoptotic cell uptake (efferocytosis) by human macrophages under inflammatory conditions. We show that whereas pro‐inflammatory stimuli consistently downregulated MerTK expression in human monocyte‐derived macrophages (MDMs), stimuli indicative of a viral infection, interferon‐α (IFN‐α) and the TLR3 ligand poly(I:C), specifically induced Axl expression and promoted binding of the bridging molecule Gas6. Axl induction by IFN‐α and poly(I:C) was associated with higher MDM efferocytic capacity compared to cells treated with other pro‐inflammatory stimuli, such as LPS and IFN‐γ. While MerTK blocking antibody uniformly suppressed apoptotic cell uptake by MDMs, Axl blocking antibody significantly reduced efferocytosis by poly(I:C)‐stimulated MDMs, but not by resting MDMs. Our observations demonstrate that Axl induction during viral infections contributes to maintaining macrophage capacity to engulf apoptotic cells, which may have important consequences for resolution of anti‐viral immune responses.

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