BackgroundThe 5XFAD early onset mouse model of Alzheimer’s disease (AD) is gaining momentum. Behavioral, electrophysiological and anatomical studies have identified age-dependent alterations that can be reminiscent of human AD. However, transcriptional changes during disease progression have not yet been investigated. To this end, we carried out a transcriptomic analysis on RNAs from the neocortex and the hippocampus of 5XFAD female mice at the ages of one, four, six and nine months (M1, M4, M6, M9).ResultsOur results show a clear shift in gene expression patterns between M1 and M4. At M1, 5XFAD animals exhibit region-specific variations in gene expression patterns whereas M4 to M9 mice share a larger proportion of differentially expressed genes (DEGs) that are common to both regions. Analysis of DEGs from M4 to M9 underlines the predominance of inflammatory and immune processes in this AD mouse model. The rise in inflammation, sustained by the overexpression of genes from the complement and integrin families, is accompanied by an increased expression of transcripts involved in the NADPH oxidase complex, phagocytic processes and IFN-γ related pathways.ConclusionsOverall, our data suggest that, from M4 to M9, sustained microglial activation becomes the predominant feature and point out that both detrimental and neuroprotective mechanisms appear to be at play in this model. Furthermore, our study identifies a number of genes already known to be altered in human AD, thus confirming the use of the 5XFAD strain as a valid model for understanding AD pathogenesis and for screening potential therapeutic molecules.

Since its discovery during the epidemic of rickets in the early 1920s, the physiological effects of vitamin D on calcium/phosphorus homeostasis have been thoroughly studied. Along with the understanding of its actions on skeletal diseases and advances in cellular and molecular biology, this misnamed vitamin has gained attention as a potential player in a growing number of physiological processes and a variety of diseases. During the last 25 years, vitamin D has emerged as a serious candidate in nervous system development and function and a therapeutic tool in a number of neurological pathologies. More recently, experimental and pre-clinical data suggest a link between vitamin D status and cognitive function. Human studies strongly support a correlation between low levels of circulating 25-hydroxyvitamin D (25(OH)D) and cognitive impairment or dementia in aging populations. In parallel, animal studies show that supplementation with vitamin D is protective against biological processes associated with Alzheimer’s disease (AD) and enhances learning and memory performance in various animal models of aging and AD. These experimental observations support multiple mechanisms by which vitamin D can act against neurodegenerative processes. However, clinical interventional studies are disappointing and fail to associate increased 25(OH)D levels with improved cognitive outcomes. This review collects the current available data from both animal and human studies and discusses the considerations that future studies examining the effects of vitamin D status on neurocognitive function might consider.

The impairment of hippocampal neurogenesis at the early stages of Alzheimer’s disease (AD) is believed to support early cognitive decline. Converging studies sustain the idea that vitamin D might be linked to the pathophysiology of AD and to hippocampal neurogenesis. Nothing being known about the effects of vitamin D on hippocampal neurogenesis in AD, we assessed them in a mouse model of AD. In a previous study, we observed that dietary vitamin D supplementation in female AD-like mice reduced cognitive decline only when delivered during the symptomatic phase. With these data in hand, we wondered whether the consequences of vitamin D administration on hippocampal neurogenesis are stage-dependent. Male wild-type and transgenic AD-like mice (5XFAD model) were fed with a diet containing either no vitamin D (0VD) or a normal dose of vitamin D (NVD) or a high dose of vitamin D (HVD), from month 1 to month 6 (preventive arm) or from month 4 to month 9 (curative arm). Working memory was assessed using the Y-maze, while amyloid burden, astrocytosis, and neurogenesis were quantified using immunohistochemistry. In parallel, the effects of vitamin D on proliferation and differentiation were assayed on primary cultures of murine neural progenitor cells. Improved working memory and neurogenesis were observed when high vitamin D supplementation was administered during the early phases of the disease, while a normal dose of vitamin D increased neurogenesis during the late phases. Conversely, an early hypovitaminosis D increased the number of amyloid plaques in AD mice while a late hypovitaminosis D impaired neurogenesis in AD and WT mice. The observed in vivo vitamin D-associated increased neurogenesis was partially substantiated by an augmented in vitro proliferation but not an increased differentiation of neural progenitors into neurons. Finally, a sexual dimorphism was observed. Vitamin D supplementation improved the working memory of males and females, when delivered during the pre-symptomatic and symptomatic phases, respectively. Our study establishes that (i) neurogenesis is improved by vitamin D in a male mouse model of AD, in a time-dependent manner, and (ii) cognition is enhanced in a gender-associated way. Additional pre-clinical studies are required to further understand the gender- and time-specific mechanisms of action of vitamin D in AD. This may lead to an adaptation of vitamin D supplementation in relation to patient’s gender and age as well as to the stage of the disease.Electronic supplementary materialThe online version of this article (10.1007/s12035-017-0839-1) contains supplementary material, which is available to authorized users.

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BackgroundIncreasing evidence suggests a potential therapeutic benefit of vitamin D supplementation against Alzheimer’s disease (AD). Although studies have shown improvements in cognitive performance and decreases in markers of the pathology after chronic treatment, the mechanisms by which vitamin D acts on brain cells are multiple and remain to be thoroughly studied. We analyzed the molecular changes observed after 5 months of vitamin D3 supplementation in the brains of transgenic 5xFAD (Tg) mice, a recognized mouse model of AD, and their wild type (Wt) littermates. We first performed a kinematic behavioural examination at 4, 6 and 8 months of age (M4, M6 and M8) followed by a histologic assessment of AD markers. We then performed a comparative transcriptomic analysis of mRNA regulation in the neocortex and hippocampus of 9 months old (M9) female mice.ResultsTranscriptomic analysis of the hippocampus and neocortex of both Wt and Tg mice at M9, following 5 months of vitamin D3 treatment, reveals a large panel of dysregulated pathways related to i) immune and inflammatory response, ii) neurotransmitter activity, iii) endothelial and vascular processes and iv) hormonal alterations. The differentially expressed genes are not all direct targets of the vitamin D-VDR pathway and it appears that vitamin D action engages in the crosstalk with estrogen and insulin signaling. The misexpression of the large number of genes observed in this study translates into improved learning and memory performance and a decrease in amyloid plaques and astrogliosis in Tg animals.ConclusionsThis study underlies the multiplicity of action of this potent neurosteroid in an aging and AD-like brain. The classical and non-classical actions of vitamin D3 can act in an additive and possibly synergistic manner to induce neuroprotective activities in a context-specific way.Electronic supplementary materialThe online version of this article (doi:10.1186/s13024-016-0087-2) contains supplementary material, which is available to authorized users.

Background Gastric hyperplastic polyps (GHPs) have a risk of neoplastic transformation reaching 5 %. Current endoscopic resection techniques appear suboptimal with a high risk of local recurrence. This study assessed the outcomes of endoscopic resection for GHPs and identified risk factors for recurrence and neoplastic transformation. Methods This retrospective, multicenter, European study included adult patients with at least one GHP ≥ 10 mm who underwent endoscopic resection and at least one follow-up endoscopy. Patients with recurrent GHPs or hereditary gastric polyposis were excluded. All data were retrieved from the endoscopy, pathology, and hospitalization reports. Results From June 2007 to August 2018, 145 GHPs in 108 patients were included. Recurrence after endoscopic resection was 51.0 % (74 /145) in 55 patients. R0 resection or en bloc resection did not impact the risk of polyp recurrence. In multivariate analysis, cirrhosis was the only risk factor for recurrence (odds ratio [OR] 4.82, 95 % confidence interval [CI] 1.33 – 17.46; P = 0.02). Overall, 15 GHPs (10.4 %) showed neoplastic transformation, with size > 25 mm (OR 10.24, 95 %CI 2.71 – 38.69; P < 0.001) and presence of intestinal metaplasia (OR 5.93, 95 %CI 1.56 – 22.47; P = 0.01) being associated with an increased risk of neoplastic transformation in multivariate analysis. Conclusions Results confirmed the risk of recurrence and neoplastic transformation of large GHPs. The risk of neoplastic change was significantly increased for lesions > 25 mm, with a risk of high grade dysplasia appearing in polyps ≥ 50 mm. The risk of recurrence was high, particularly in cirrhosis patients, and long-term follow-up is recommended in such patients.

Rationale Patients with a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are at higher risk of ventilator-associated pneumonia (VAP) and may have an increased attributable mortality (increased or decreased risk of death if VAP occurs in a patient) and attributable fraction (proportion of deaths that are attributable to an exposure) of VAP-related mortality compared with subjects without coronavirus disease (COVID-19). Objectives Estimation of the attributable mortality of the VAP among patients with COVID-19. Methods Using the REA-REZO surveillance network, three groups of adult medical ICU patients were computed: control group (patients admitted between 2016 and 2019; prepandemic patients), pandemic COVID-19 group (PandeCOV + ), and pandemic non–COVID-19 group (PandeCOV − ) admitted during 2020. The primary outcome was the estimation of attributable mortality and attributable fraction related to VAP in these patients. Using multistate modeling with causal inference, the outcomes related to VAP were also evaluated. Measurements and Main Results A total of 64,816 patients were included in the control group, 7,442 in the PandeCOV − group, and 1,687 in the PandeCOV + group. The incidence of VAP was 14.2 (95% confidence interval [CI], 13.9 to 14.6), 18.3 (95% CI, 17.3 to 19.4), and 31.9 (95% CI, 29.8 to 34.2) per 1,000 ventilation-days in each group, respectively. Attributable mortality at 90 days was 3.15% (95%, CI, 2.04% to 3.43%), 2.91% (95% CI, −0.21% to 5.02%), and 8.13% (95% CI, 3.54% to 12.24%), and attributable fraction of mortality at 90 days was 1.22% (95% CI, 0.83 to 1.63), 1.42% (95% CI, −0.11% to 2.61%), and 9.17% (95% CI, 3.54% to 12.24%) for the control, PandeCOV − , and PandeCOV + groups, respectively. Except for the higher risk of developing VAP, the PandeCOV − group shared similar VAP characteristics with the control group. PandeCOV + patients were at lower risk of death without VAP (hazard ratio, 0.62; 95% CI, 0.52 to 0.74) than the control group. Conclusions VAP-attributable mortality was higher for patients with COVID-19, with more than 9% of the overall mortality related to VAP.

Objective: Narrow-Band Imaging (NBI) is as sensitive as Lugol chromoendoscopy to detect oesophageal squamous cell carcinoma (SCC) but its specificity, which appears higher than than that of Lugol chromoendoscopy in expert centres, remains to be established in current practice. This study aimed to prove the superiority of NBI specificity over Lugol chromoendoscopy in the detection of oesophageal SCC and high-grade dysplasia (HGD) in current practice (including tertiary care centres, local hospitals, and private clinics). Trial Design: Prospective randomised multicentre trial including consecutive patients with previous or current SCC of the upper aerodigestive tract addressed for gastroscopy. Patients included were randomly allocated to either the Lugol or NBI group. In the Lugol group, examination with white light and Lugol chromoendoscopy were successively performed. In the NBI group, NBI exam was performed after white light endoscopy. We compared the diagnostic characteristics of NBI and Lugol chromoendoscopy in a per-patient analysis. Results: 334 patients with previous history of SCC were included and analysed in intention-to-tret from 15 French institutions between March 2011 and December 2015. In a per-patient analysis, sensitivity, specificity, positive and negative likelihood values were respectively 100%, 66.0%, 21.2%, and 100% for Lugol chromoendoscopy vs. 100%, 79.9%, 37.5%, and 100% for NBI. NBI specificity was greater than Lugol chromoendoscopy (p=0.0023). Conclusions: As previously demonstrated in expert centres, NBI is more specific than Lugol in current gastroenterology practice for the detection of early SCC but combined approaches with both NBI and lugol could improve the detection of squamous neoplasia.