Revisiting idiopathic eosinophilic myositis: towards a clinical-pathological continuum from the muscle to the fascia and skin.

OBJECTIVES: Idiopathic inflammatory myopathies are mainly defined by inflammatory infiltrates within the muscle (lymphocytes and macrophages). Eosinophil muscle infiltration has been described in idiopathic eosinophilic myositis (IEM) and rarely in EF. This study aimed to further delineate the nosological frame of idiopathic eosinophil muscle infiltration through the exhaustive analysis of IEM and EF patients. METHODS: This multicentre retrospective case series included IEM patients diagnosed between 2000 and 2022. IEM inclusion criteria were eosinophilic muscle infiltration with myositis pathological features, after the exclusion of differential diagnoses. An additional group of EF patients diagnosed between 2016 and 2022 was constituted. Inclusion criteria were an EF diagnosis and fascia thickening with inflammatory infiltrate. RESULTS: A total of 20 IEM cases and 10 EF cases were included. The median (interquartile range) age at diagnosis was 65 (49-70) years; there were 18 males. Data analysis delineated four subgroups: focal EM (FEM, n = 3), diffuse EM (DEM, n = 6), eosinophilic myofasciitis (EMF, n = 11) and EF (n = 10). FEM represented a limited and benign form of myositis. DEM cases presented objective muscle impairment with eosinophilic muscle infiltration. EMF patients presented subjective muscle impairment (myalgia, 55%), fasciitis (on histology and/or imaging), eosinophilic muscle infiltration and frequent hypereosinophilia (55%). EF patients presented myalgia (50%), muscle lesions on histology with fascia-restricted inflammatory infiltrates with (60%) or without (40%) eosinophils. CONCLUSIONS: The analysis of IEM and EF patient characteristics delineates four subgroups (FEM, DEM, EMF and EF) in terms of clinical, laboratory, imaging, pathological and outcome specificities, and proposes an adapted diagnostic and care management approach.

Attributable Mortality of Ventilator-associated Pneumonia Among Patients with COVID-19.

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.

Digestive perforations related to endoscopy procedures: a local management charter based on local evidence and experts' opinion.

Background and study aims Perforations are a known adverse event of endoscopy procedures; a proposal for appropriate management should be available in each center as recommended by the European Society of Gastrointestinal Endoscopy. The objective of this study was to establish a charter for the management of endoscopic perforations, based on local evidence. Patients and methods Patients were included if they experienced partial or complete perforation during an endoscopic procedure between 2008 and 2018 (retrospectively until 2016, then prospectively). Perforations (size, location, closure) and management (imagery, antibiotics, surgery) were analyzed. Using these results, a panel of experts was asked to propose a consensual management charter. Results A total of 105 patients were included. Perforations occurred mainly during therapeutic procedures (91, 86.7%). Of the perforations, 78 (74.3 %) were diagnosed immediately and managed during the procedure; 69 of 78 (88.5 %) were successfully closed. Closures were more effective during therapeutic procedures (60 of 66, 90.9 %) than during diagnostic procedures (9 of 12, 75.0 %, P  = 0.06). Endoscopic closure was effective for 37 of 38 perforations (97.4 %) < 0.5 cm, and for 26 of 34 perforations (76.5 %) ≥ 0.5 cm ( P  < 0.05). For perforations < 0.5 cm, systematic computed tomography (CT) scan, antibiotics, or surgical evaluation did not improve the outcome. Four of 105 deaths (3.8 %) occurred after perforation, one of which was attributable to the perforation itself. Conclusions Detection and closure of perforations during endoscopic procedure had a better outcome compared to delayed perforations; perforations < 0.5 cm had a very good prognosis and CT scan, surgeon evaluation, or antibiotics are probably not necessary when the endoscopic closure is confidently performed. This work led to proposal of a local management charter.

Association Between Short-, Intermediate-, and Long-term Mortality and Myocardial Injury After Noncardiac Surgery After Hip Fracture Surgery: A Retrospective Cohort.

BACKGROUND: For more than 20 years, hip fracture 1-year mortality has remained around 20%. An elevation of the postoperative troponin peak within 72 hours (myocardial injury after noncardiac surgery [MINS]) is associated with a greater risk of short-term mortality in the general population. However, there seem to be conflicting results in the specific population who undergo hip fracture surgery, with some studies finding an association between troponin and mortality and some not. The objective of the present study was to investigate the association of MINS and the short- (before 28th day), intermediate- (before 180th day), and long-term (before 365th day) mortality after hip fracture surgery. METHODS: We conducted a single-center retrospective cohort of patients undergoing hip fracture surgery from November 2013 to December 2015. MINS was defined as postoperative troponin peak within the 72 hours >5 ng/L. Four MINS subgroups were defined according to the value of troponin peak (ie, ≥5-<20, ≥20-<65, ≥65-<1000, and ≥1000 ng/L). To document the association between the different mortality terms and the troponin peak, odds ratio (OR) and adjusted OR (aOR) associated with their 95% confidence interval (CI) with the log of the scaled troponin peak within 72 hours were estimated, with and without patients presenting a postoperative acute coronary syndrome (ACS). Cox proportional hazards modeling was used to estimate hazard ratio (HR) and adjusted HR (aHR) of death between the no MINS and MINS subgroups. The adjustment was performed on the main confounding factors (ie, sex, American Society of Anesthesiologists [ASA] physical status, dementia status, age, and time from admission to surgery). RESULTS: Among 729 participants, the mean age was 83.1 (standard deviation [SD] = 10.8) years, and 77.4% were women; 30 patients presented an ACS (4%). Short-, intermediate-, and long-term mortality were at 5%, 16%, and 23%, respectively. The troponin peak was significantly associated with all terms of mortality before and after adjustment and before and after exclusion of patients presenting an ACS. HR and aHR for each subgroup of troponin level were significantly associated with an increased probability of survival, except for the 5 to 20 ng/L group for which aHR was not significant (1.75, 95% CI, 0.82-3.74). In the landmark analysis, there was still an association between survival at the 365th day and troponin peak after the short- and intermediate-term truncated mortality. CONCLUSIONS: MINS is associated with short-, intermediate-, and long-term mortality after hip fracture surgery. This could be a valuable indicator to determine the population at high risk of mortality that could benefit from targeted prevention and possible intervention.

Narrow-band imaging versus Lugol chromoendoscopy for esophageal squamous cell cancer screening in normal endoscopic practice: randomized controlled trial.

BACKGROUND: Narrow-band imaging (NBI) is as sensitive as Lugol chromoendoscopy to detect esophageal squamous cell carcinoma (SCC) but its specificity, which appears higher than that of Lugol chromoendoscopy in expert centers, remains to be established in general practice. This study aimed to prove the superiority of NBI specificity over Lugol chromoendoscopy in the detection of esophageal SCC and high grade dysplasia (HGD) in current general practice (including tertiary care centers, local hospitals, and private clinics). METHODS: This prospective randomized multicenter trial included consecutive patients with previous or current SCC of the upper aerodigestive tract who were scheduled for gastroscopy. Patients 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 examination 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 history of SCC were included and analyzed (intention-to-treat) from 15 French institutions between March 2011 and December 2015. In per-patient analysis, sensitivity, specificity, positive and negative likelihood values were 100 %, 66.0 %, 21.2 %, and 100 %, respectively, for Lugol chromoendoscopy vs. 100 %, 79.9 %, 37.5 %, and 100 %, respectively, for NBI. Specificity was greater with NBI than with Lugol (P = 0.002). CONCLUSIONS: As previously demonstrated in expert centers, NBI was 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.

ctDNA in Neuroendocrine Carcinoma of Gastroenteropancreatic Origin or of Unknown Primary: The CIRCAN-NEC Pilot Study.

INTRODUCTION: Gastroenteropancreatic neuroendocrine carcinomas (GEPNEC) are characterized by a heterogeneous molecular profile and a poor prognosis. Circulating tumour DNA (ctDNA) analysis may be useful for NEC management. This study aimed at describing ctDNA mutations, to assess their predictive value for response to chemotherapies, and their change according to disease progression. METHODS: The CIRCAN-NEC study included patients with GEPNEC or NEC from an unknown primary, scheduled to begin first- or second-line chemotherapy. Blood samples were collected prior to chemotherapy initiation, at first evaluation, and during disease progression. ctDNA was sequenced by next-generation sequencing (NGS). Molecular response was defined as a decrease of at least 30% of the mutant allele fraction. RESULTS: All 24 patients included received platinum-etoposide first-line chemotherapy; 19 received a FOLFIRI-based post-first-line regimen. Twenty-two patients had at least one driver mutation: TP53 (n = 21), RB1 (n = 2), KRAS (n = 4), and BRAF (n = 3). Ten (42%) had an "adenocarcinoma-like" profile. Five of 6 patients with matching ctDNA/tissue NGS harboured at least one concordant mutation (44% concordance at the gene level). The concordance rate between ctDNA mutation/immunohistochemistry profile was 64% (7/11) for TP53/p53+ and 14% (1/7) for RB1/pRb-. In this pilot study including few patients by subgroups, patients with KRAS (HR = 3.60, 95% CI [1.06-12.04]) and BRAF (HR = 4.25, 95% CI [1.11-16.40]) mutations had shorter progression-free survival (PFS) under platinum-etoposide, while the 2 patients with RB1 mutations had shorter PFS under FOLFIRI-based chemotherapy. Twenty-eight periods of treatment were assessed: 10 patients had a molecular response (7/10 had a morphological response), which was associated with longer PFS (HR = 0.37, 95% CI [0.15; 0.91]). CONCLUSION: This pilot study shows a high sensitivity of ctDNA assessment, which is encouraging for the future management of GEPNEC (tumour molecular diagnosis and evaluation of disease progression).

Risk of neoplastic change in large gastric hyperplastic polyps and recurrence after endoscopic resection.

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.

The Influence of Vitamin D on Neurodegeneration and Neurological Disorders: A Rationale for its Physio-pathological Actions.

Vitamin D is a steroid hormone implicated in the regulation of neuronal integrity and many brain functions. Its influence, as a nutrient and a hormone, on the physiopathology of the most common neurodegenerative diseases is continuously emphasized by new studies. This review addresses what is currently known about the action of vitamin D on the nervous system and neurodegenerative diseases such as Multiple Sclerosis, Alzheimer's disease, Parkinson's disease and Amyotrophic Lateral Sclerosis. Further vitamin D research is necessary to understand how the action of this "neuroactive" steroid can help to optimize the prevention and treatment of several neurological diseases.

Cholecalciferol (Vitamin D3) Reduces Rat Neuropathic Pain by Modulating Opioid Signaling.

The impact of vitamin D on sensory function, including pain processing, has been receiving increasing attention. Indeed, vitamin D deficiency is associated with various chronic pain conditions, and several lines of evidence indicate that vitamin D supplementation may trigger pain relief. However, the underlying mechanisms of action remain poorly understood. We used inflammatory and non-inflammatory rat models of chronic pain to evaluate the benefits of vitamin D3 (cholecalciferol) on pain symptoms. We found that cholecalciferol supplementation improved mechanical nociceptive thresholds in monoarthritic animals and reduced mechanical hyperalgesia and cold allodynia in a model of mononeuropathy. Transcriptomic analysis of cerebrum, dorsal root ganglia, and spinal cord tissues indicate that cholecalciferol supplementation induces a massive gene dysregulation which, in the cerebrum, is associated with opioid signaling (23 genes), nociception (14), and allodynia (8), and, in the dorsal root ganglia, with axonal guidance (37 genes) and nociception (17). Among the identified cerebral dysregulated nociception-, allodynia-, and opioid-associated genes, 21 can be associated with vitamin D metabolism. However, it appears that their expression is modulated by intermediate regulators such as diverse protein kinases and not, as expected, by the vitamin D receptor. Overall, several genes-Oxt, Pdyn, Penk, Pomc, Pth, Tac1, and Tgfb1-encoding for peptides/hormones stand out as top candidates to explain the therapeutic benefit of vitamin D3 supplementation. Further studies are now warranted to detail the precise mechanisms of action but also the most favorable doses and time windows for pain relief.

Expression of the Cerebral Olfactory Receptors Olfr110/111 and Olfr544 Is Altered During Aging and in Alzheimer's Disease-Like Mice.

A growing number of studies report the expression of olfactory receptors (ORs) in many non-chemosensory tissues and organs. However, within the brain, very few ectopic ORs are exhaustively documented. Their kinetic expression, cellular localization, and functions remain elusive. Using cDNA microarrays, quantitative PCR, and immunohistochemistry, we studied the cellular and sub-cellular localization of Olfr110/111 and Olfr544 and their timely expression in various brain areas of wild-type and transgenic Alzheimer's disease-like (5xFAD) mice. We observed that Olfr110/111 and Olfr544 proteins are mainly expressed by neurons in cortical and hippocampal regions and, to a lesser extent, by astrocytes, microglia, oligodendrocytes, and endothelial cells. In addition, both ORs are present at the cell membrane and co-expressed with the olfactory Gαolf protein, suggesting that they can be functional. Remarkably, we also found that the expression of the mRNA encoding for Olfr110/111 tends to increase with age in both the cortex and hippocampus of wild-type and transgenic mice. Moreover, Olfr110/111 transcript expression is markedly impaired in the brain of Alzheimer's disease-like mice. A different profile is noticed for Olfr544, for which an overexpression is observed only in the cortex of 9-month-old animals. In addition, in transgenic mice, olfactory receptors are observed near amyloid plaques. Altogether, our findings indicate that ORs may play a role in brain functioning, in normal and pathological conditions.

Vitamin D Improves Neurogenesis and Cognition in a Mouse Model of Alzheimer's Disease.

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.

Differential expression of vitamin D-associated enzymes and receptors in brain cell subtypes.

Accumulating evidence indicates that the active form of vitamin D, 1,25(OH)2D3, can be considered as a neurosteroid. However, the cerebral expression of vitamin D-associated enzymes and receptors remains controversial. With the idea of carrying out a comparative study in mind, we compared the transcript expression of Cyp27a1, Cyp27b1, Cyp24a1, Vdr and Pdia3 in purified cultures of astrocytes, endothelial cells, microglia, neurons and oligodendrocytes. We observed that endothelial cells and neurons can possibly transform the inactive cholecalciferol into 25(OH)D3. It can then be metabolised into 1,25(OH)2D3, by neurons or microglia, before being transferred to astrocytes where it can bind to VDR and initiate gene transcription or be inactivated when in excess. Alternatively, 1,25(OH)2D3 can induce autocrine or paracrine rapid non-genomic actions via PDIA3 whose transcript is abundantly expressed in all cerebral cell types. Noticeably, brain endothelial cells appear as a singular subtype as they are potentially able to transform cholecalciferol into 25(OH)D3 and exhibit a variable expression of Pdia3, according to 1,25(OH)2D3 level. Altogether, our data indicate that, within the brain, vitamin D may trigger major auto-/paracrine non genomic actions, in addition to its well documented activities as a steroid hormone.

Vitamin D, Cognition and Alzheimer's Disease: The Therapeutic Benefit is in the D-Tails.

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.

Vitamin D interacts with Esr1 and Igf1 to regulate molecular pathways relevant to Alzheimer's disease.

BACKGROUND: Increasing 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. RESULTS: Transcriptomic 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. CONCLUSIONS: This 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.

Temporal gene profiling of the 5XFAD transgenic mouse model highlights the importance of microglial activation in Alzheimer's disease.

BACKGROUND: The 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). RESULTS: Our 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. CONCLUSIONS: Overall, 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.

[Role of vitamin D in the physiopathology of neurodegenerative diseases]. / Rôle de la vitamine D dans la physiopathologie des maladies neurodégénératives.

The involvement of vitamin D in brain function has been discovered in the past 25 years by epidemiological and fundamental studies. Research on neurodegenerative diseases and their animal or cellular models unveiled converging lines of evidence indicating that hypovitaminosis D is not just an effect of the progression of neurodegenerative diseases, but truly an aggravating co-factor, sometimes very closely related to their physiopathology. Vitamin D is a steroid hormone capable of regulating the expression of hundreds of genes through both genetic and epigenetic mechanisms. This reflects the highly pleiotropic nature of its action in its conventional bone and phosphocalcic metabolism targets. Its role in the central nervous system and neurodegenerative diseases makes no exception to this rule. Here we focus on the identified role and mechanisms of vitamin D in multiple sclerosis, Alzheimer's disease and Parkinson's disease. The important prevalence of hypovitaminosis D under our latitudes in general and in at-risk groups in particular, its easy evaluation and correction, and the results of early clinical studies, suggest that vitamin D supplementation could usefully complement our therapeutic armory to fight these diseases.

Prenatal vitamin D deficiency induces an early and more severe experimental autoimmune encephalomyelitis in the second generation.

In a previous study, we demonstrated that mouse adult F(1) offspring, exposed to a vitamin D deficiency during pregnancy, developed a less severe and delayed Experimental Autoimmune Encephalomyelitis (EAE), when compared with control offspring. We then wondered whether a similar response was observed in the subsequent generation. To answer this question, we assessed F(2) females whose F(1) parents (males or females) were vitamin D-deprived when developing in the uterus of F(0) females. Unexpectedly, we observed that the vitamin D deficiency affecting the F(0) pregnant mice induced a precocious and more severe EAE in the F(2) generation. This paradoxical finding led us to assess its implications for the epidemiology of Multiple Sclerosis (MS) in humans. Using the REFGENSEP database for MS trios (the patient and his/her parents), we collected the parents' dates of birth and assessed a potential season of birth effect that could potentially be indicative of the vitamin D status of the pregnant grandmothers. A trend for a reduced number of births in the Fall for the parents of MS patients was observed but statistical significance was not reached. Further well powered studies are warranted to validate the latter finding.

Seasonal, gestational and postnatal influences on multiple sclerosis: the beneficial role of a vitamin D supplementation during early life.

There is now strong evidence linking vitamin D, the steroid hormone of sunlight, and Multiple Sclerosis (MS). Two of the most intriguing findings are the season of birth and childhood sun exposure effects. They both suggest that a vitamin D deficiency during these critical imprinting periods is a risk factor for MS. After having confirmed that people born in November are at lower risk of developing MS, we devised a mouse model of prenatal vitamin D deficiency. We observed that adult offspring born to vitamin D deficient mothers, when compared to control offspring, developed a striking milder and delayed experimental autoimmune encephalomyelitis (EAE) and permanently overexpressed the vitamin D receptor. This unexpected finding led us to conjecture that the newborns, after having known an in utero vitamin D-deficient environment, were highly sensitive ex utero to cholecalciferol-containing diet and interpreted the postnatal food as a vitamin D enriched environment. To validate this hypothesis, we devised a mouse model of postnatal vitamin D supplementation. Interestingly, using the same EAE model, we demonstrated that a delayed onset and less severe symptoms were displayed by postnatally vitamin D-supplemented mice. The latter finding is in accordance with previous animal studies demonstrating that a postnatal vitamin D deficiency induced an earlier onset and an increased symptom severity of EAE and epidemiological reports describing the importance of an adequate supply of vitamin D during early life.