Temporal Integrative Analysis of mRNA and microRNAs Expression Profiles and Epigenetic Alterations in Female SAMP8, a Model of Age-Related Cognitive Decline

A growing body of research shows that epigenetic mechanisms are critically involved in normal and pathological aging. The Senescence-Accelerated Mouse Prone 8 (SAMP8) can be considered a useful tool to better understand the dynamics of the global epigenetic landscape during the aging process since its phenotype is not fully explained by genetic factors. Here we investigated dysfunctional age-related transcriptional profiles and epigenetic programming enzymes in the hippocampus of 2- and 9-month-old SAMP8 female mice using the Senescent-Accelerated Resistant 1 (SAMR1) mouse strain as control. SAMP8 mice presented 1,062 genes dysregulated at 2 months of age, and 1,033 genes at 9 months, with 92 genes concurrently dysregulated at both ages compared to age-matched SAMR1. SAMP8 mice showed a significant decrease in global DNA methylation (5-mC) at 2 months while hydroxymethylation (5-hmC) levels were increased in SAMP8 mice at 2 and 9 months of age compared to SAMR1. These changes were accompanied by changes in the expression of several enzymes that regulate 5-mC and methylcytosine oxidation. Acetylated H3 and H4 histone levels were significantly diminished in SAMP8 mice at 2-month-old compared to SAMR1 and altered Histone DeACetylase (HDACs) profiles were detected in both young and old SAMP8 mice. We analyzed 84 different mouse miRNAs known to be altered in neurological diseases or involved in neuronal development. Compared with SAMR1, SAMP8 mice showed 28 and 17 miRNAs differentially expressed at 2 and 9 months of age, respectively; 6 of these miRNAs overlapped at both ages. We used several bioinformatic approaches to integrate our data in mRNA:miRNA regulatory networks and functional predictions for young and aged animals. In sum, our study reveals interplay between epigenetic mechanisms and gene networks that seems to be relevant for the progression toward a pathological aging and provides several potential markers and therapeutic candidates for Alzheimer's Disease (AD) and age-related cognitive impairment

Epigenetic alterations in hippocampus of SAMP8 senescent mice and modulation by voluntary physical exercise

The senescence-accelerated SAMP8 mouse model displays features of cognitive decline and Alzheimer's disease. With the purpose of identifying potential epigenetic markers involved in aging and neurodegeneration, here we analyzed the expression of 84 mature miRNAs, the expression of histone-acetylation regulatory genes and the global histone acetylation in the hippocampus of 8-month-old SAMP8 mice, using SAMR1 mice as control. We also examined the modulation of these parameters by 8 weeks of voluntary exercise. Twenty-one miRNAs were differentially expressed between sedentary SAMP8 and SAMR1 mice and seven miRNAs were responsive to exercise in both strains. SAMP8 mice showed alterations in genes involved in protein acetylation homeostasis such as Sirt1 and Hdac6 and modulation of Hdac3 and Hdac5 gene exprssion by exercise. Global histone H3 acetylation levels were reduced in SAMP8 compared with SAMR1 mice and reached control levels in response to exercise. In sum, data presented here provide new candidate epigenetic markers for aging and neurodegeneration and suggest that exercise training may prevent or delay some epigenetic alterations associated with accelerated aging

Microglial hyperreactivity evolved to immunosuppression in the hippocampus of a mouse model of accelerated aging and Alzheimer’s Disease traits

Neuroinflammation is a risk factor for Alzheimer’s disease (AD). We sought to study the glial derangement in AD using diverse experimental models and human brain tissue. Besides classical pro-inflammatory cytokines, we analyzed chitinase 3 like 1 (CHI3L1 or YKL40) and triggering receptor expressed on myeloid cells 2 (TREM2) that are increasingly being associated with astrogliosis and microgliosis in AD, respectively. The SAMP8 mouse model of accelerated aging and AD traits showed elevated pro-inflammatory cytokines and activated microglia phenotype. Furthermore, 6-month-old SAMP8 showed an exacerbated inflammatory response to peripheral lipopolysaccharide in the hippocampus and null responsiveness at the advanced age (for this strain) of 12 months.This research was funded by Spanish MINECO and European Regional Development Fund, grant number SAF2016- 77703; Spanish MCINN, grant number PID2019-106285RB; Catalan Autonomous Government AGAUR, grant number 2017-SGR-106; Competitiveness Operational Programme 2014-2020, C-Reactive protein therapy for stroke-associated dementia, ID P_37_674, MySMIS code: 103432, contract 51/05.09.2016; and the CERCA Programme/Generalitat de Catalunya. RCo was supported by a post-doctoral research contract of the Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Instituto de Salud Carlos III, Madrid, Spain. AL (PERIS SLT008/18/00061) received funding from Departament de Salut de la Generalitat de Catalunya. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)

Long-term exercise modulates hippocampal gene expression in sencescent females mice

Altres ajuts: FI-DGR 2011 de la Generalitat de CatalunyaThe senescence-accelerated SAMP8 mouse is considered a useful non-transgenic model for studying aspects of progressive cognitive decline and Alzheimer's disease (AD). Using SAMR1 mice as controls, here we explored the effects of 6 months of voluntary wheel running in 10-month-old female SAMP8 mice. Exercise in SAMP8 mice improved phenotypic features associated with premature aging (i.e., skin color and body tremor) and enhanced vascularization and BDNF gene expression in the hippocampus compared with controls. With the aim of identifying genes involved in brain aging responsive to long-term exercise, we performed whole genome microarray studies in hippocampus from sedentary SAMP8 (P8sed), SAMR1 (R1sed), and exercised SAMP8 (P8run) mice. The genes differentially expressed in P8sed versus R1sed were considered as putative aging markers (i) and those differentially expressed in P8run versus P8sed were considered as genes modulated by exercise (ii). Genes differentially expressed in both comparisons (i and ii) were considered as putative aging genes responsive to physical exercise. We identified 34 genes which met both criteria. Gene ontology analysis revealed that they are mainly involved in functions related to extracellular matrix maintenance. Selected genes were validated by real-time quantitative PCR assays, i.e., collagen type 1 alpha 1 (col1a1), collagen type 1 alpha 2 (col1a2), fibromodulin (fmod), prostaglandin D(2) synthase (ptgds), and aldehyde dehydrogenase (Aldh1a2). As a whole, our study suggests that exercise training during adulthood may prevent or delay gene expression alterations and processes associated with hippocampal aging in at-risk subjects

The Potential of Sewage Sludge to Predict and Evaluate the Human Chemical Exposome

Chemicals are part of our daily lives, and we are exposed to numerous chemicals through multiple pathways. Relevant scientific evidence contributing to the regulation of hazardous chemicals require a holistic approach to assess simultaneous exposure to multiple compounds. Biomonitoring provides an accurate estimation of exposure to chemicals through very complex and costly sampling campaigns. Finding efficient proxies to predict the risk of chemical exposure in humans is an urgent need to cover large areas and populations at a reasonable cost. We conducted an exploratory study to characterize the human chemical exposome in maternal blood and placenta samples of a population-based birth cohort in Barcelona (2018-2021). Ultimate HRMS-based approaches were applied including wide-scope target, suspect, and nontarget screening. Forty-two chemicals were identified including pesticides, personal care products, or industrial compounds, among others, in the range of ng/mL and ng/g. In parallel, sewage sludge from the wastewater treatment plants serving the residence areas of the studied population were also screened, showing correlations with the type and concentrations of chemicals found in humans. Our findings were suggestive for the potential use of sewage sludge as a proxy of the human exposure and its application in early warning systems to prevent bioaccumulation of hazardous chemicals.This work received support from the “La Caixa” Foundation (ID 100010434), fellowship code LCF/BQ/PR20/11770013, and Barcelona Council (Expo-Bar). The BiSC cohort study is funded by the European Research Council (ERC) under Grant Agreement No. 785994 (AIR-NB), and the Health Effects Institute (HEI) with Grant Agreement No. 4959-RFPA15-1/ 18-1 (FRONTIER). IDAEA-CSIC and ISGlobal are Centres of Excellence Severo Ochoa (Spanish Ministry of Science and Innovation).Peer reviewe

Assessment of exposure to trace metals in a cohort of pregnant women from an urban center by urine analysis in the first and third trimesters of pregnancy

Background: Prenatal exposure to trace metals, whether they are essential, non-essential or toxic, must be assessed for their potential health effects in the offspring. Herein is reported a preliminary approach to this end which involved collection of urine samples during the first and third trimesters of pregnancy from 489 mothers from Sabadell (Catalonia, Spain), a highly industrialized town. These samples were analyzed for cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), selenium (Se), arsenic (As), molybdenum (Mo), cadmium (Cd), antimonium (Sb), cesium (Cs), thallium (Th) and lead (Pb). Results: An acid digestion method was developed and validated for Q-ICP-MS analysis of these 12 metals. The median concentrations of metals ranged from 0.13 to 290 μg/g creatinine, the highest levels were found for Zn and the lowest for Th. The mean concentrations of most metals except As, Ni, Th and Pb showed statistically significant differences between both trimesters. The concentrations of Mo, Se, Cd, Cs and Sb were higher in the first than in the third trimester, whereas the opposite was found for Co, Cu and Zn. The concentrations of all metals in both sampling periods showed statistically significant correlations (p<0.01 for Mo and Cu, p<0.001 for the others). Conclusions: The significant correlations of metal urine concentrations in the first and third trimesters of pregnancey suggest that the observed differences between both periods are related to physiological changes. Accordingly, the measured urine concentrations during either the first or third trimesters can be used as estimates of exposure during pregnancy and can serve as markers for prenatal intake of these metals in the studied cohort.  Peer reviewe

Resveratrol upregulates the expression of antioxidant genes inimmortalized AD lymphocytes

Trabajo presentado en el XI Simposi de Neurobiologia: Future technical advances, organizado por la Socitat Catalana de Biologia, en Barcelona, los días 12 y 13 de noviembre de 2018Alzheimer’s disease (AD) is the most common neurodegenerative disorder and first cause of dementia all over the world. It is characterized by a progressive neuronal loss. The main risk factor for developing AD is the age. Major pathological hallmarks include extracellular deposits of amyloid protein and intracellular deposits of neurofibrillary tau protein. AD brain also shows alterations developed in aged brain such as oxidative stress and inflammation. The study used immortalized lymphocytes from patients of sporadic AD and age-matched healthy controls (HC) with the following aims: First, analyze gene expression of oxidative stress and aging-related pathways in AD and HC lymphoblast cell lines. Next, investigate the potential role of resveratrol as antiaging and protective agent through the induction of further gene expression changes. Finally, establish the different sensitivity between the human immortalized lymphocyte cell lines and the human neuroblastoma cell line SH-SY5Y to the hormetic agent resveratrol and to oxidative stress inductors. Real-time PCR showed that oxidative stress and aging-related genes were differentially expressed in AD lymphoblasts compared to HC lymphoblasts with increases in CASP1, TXNIP, VPS13C, GPX1, PRDX5, SOD2, and decrease in CCS expression. Resveratrol incubated for 18h at concentration of 10, 20 or 50µM induced a general upregulation of antioxidant and detoxifying genes such as: CAT, NFE2L2, GSTZ1, and CCS, in both HC and AD lymphoblasts. Resveratrol also induced the expression of the anti-aging mitochondrial sirtuin SIRT3. At the concentrations tested, resveratrol was not cytotoxic to lymphoblast or SH-SY5Y neuroblastoma cultures, although the later were more sensitive to oxidative injuries. This study supports that immortalized lymphocytes is a suitable cell system to analyze molecular alterations of pathways common to non-neural and neural cells. Furthermore, resveratrol upregulation of antioxidant genes may contribute to improve physiological processes in aging and AD.Supprted by grants: SAF2016‐77703, MINECO and ERDF; 2017-SGR-106, AGAURPeer reviewe

Evaluating the association between placenta DNA methylation and cognitive functions in the offspring

The placenta plays a crucial role in protecting the fetus from environmental harm and supports the development of its brain. In fact, compromised placental function could predispose an individual to neurodevelopmental disorders. Placental epigenetic modifications, including DNA methylation, could be considered a proxy of placental function and thus plausible mediators of the association between intrauterine environmental exposures and genetics, and childhood and adult mental health. Although neurodevelopmental disorders such as autism spectrum disorder have been investigated in relation to placenta DNA methylation, no studies have addressed the association between placenta DNA methylation and child's cognitive functions. Thus, our goal here was to investigate whether the placental DNA methylation profile measured using the Illumina EPIC array is associated with three different cognitive domains (namely verbal score, perceptive performance score, and general cognitive score) assessed by the McCarthy Scales of Children's functions in childhood at age 4. To this end, we conducted epigenome-wide association analyses, including data from 255 mother-child pairs within the INMA project, and performed a follow-up functional analysis to help the interpretation of the findings. After multiple-testing correction, we found that methylation at 4 CpGs (cg1548200, cg02986379, cg00866476, and cg14113931) was significantly associated with the general cognitive score, and 2 distinct differentially methylated regions (DMRs) (including 27 CpGs) were significantly associated with each cognitive dimension. Interestingly, the genes annotated to these CpGs, such as DAB2, CEP76, PSMG2, or MECOM, are involved in placenta, fetal, and brain development. Moreover, functional enrichment analyses of suggestive CpGs (p < 1 × 10−4) revealed gene sets involved in placenta development, fetus formation, and brain growth. These findings suggest that placental DNA methylation could be a mechanism contributing to the alteration of important pathways in the placenta that have a consequence on the offspring's brain development and cognitive function

Prenatal maternal smoke, DNA methylation, and multi-omics of tissues and child health

Purpose of review: Maternal tobacco smoking during pregnancy is of public health concern, and understanding the biological mechanisms can help to promote smoking cessation campaigns. This non-systematic review focuses on the effects of maternal smoking during pregnancy on offspring's epigenome, consistent in chemical modifications of the genome that regulate gene expression. Recent findings: Recent meta-analyses of epigenome-wide association studies have shown that maternal smoking during pregnancy is consistently associated with offspring's DNA methylation changes, both in the placenta and blood. These studies indicate that effects on blood DNA methylation can persist for years, and that the longer the duration of the exposure and the higher the dose, the larger the effects. Hence, DNA methylation scores have been developed to estimate past exposure to maternal smoking during pregnancy as biomarkers. There is robust evidence for DNA methylation alterations associated with maternal smoking during pregnancy; however, the role of sex, ethnicity, and genetic background needs further exploration. Moreover, there are no conclusive studies about exposure to low doses or during the preconception period. Similarly, studies on tissues other than the placenta and blood are scarce, and cell-type specificity within tissues needs further investigation. In addition, biological interpretation of DNA methylation findings requires multi-omics data, poorly available in epidemiological settings. Finally, although several mediation analyses link DNA methylation changes with health outcomes, they do not allow causal inference. For this, a combination of data from multiple study designs will be essential in the future to better address this topic.The study has received funding from the H2020-EU.3.1.2.—Preventing Disease Programme under grant agreement no 874583 (ATHLETE project). Marta Cosin-Tomas is funded by a Beatriu de Pinós Postdoctoral Contract awarded by Generalitat de Catalunya-AGAUR and European Commission- Horizon 2020 (2019 BP 00107). Ariadna Cilleros-Portet is funded by a grant from the Health Department of the Basque Government to Nora Fernandez-Jimenez (GVSAN-2019111085). Sofía Aguilar-Lacasaña is funded by a FI-AGAUR Predoctoral contract awarded by the Agència de Gestió d'Ajuts Universitaris i de Recerca (2022 FI_B 00797), Generalitat de Catalunya – Fons Social Europeu. We received support from the Spanish Ministry of Science and Innovation and State Research Agency through the “Centro de Excelencia Severo Ochoa 2019–2023” Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program

Moderate Folic Acid Supplementation in Pregnant Mice Results in Altered Sex-Specific Gene Expression in Brain of Young Mice and Embryos

Food fortification and increased vitamin intake have led to higher folic acid (FA) consumption by many pregnant women. We showed that FA-supplemented diet in pregnant mice (fivefold higher FA than the recommended level (5xFASD)) led to hyperactivity-like behavior and memory impairment in pups. Disturbed choline/methyl metabolism and altered placental gene expression were identified. The aim of this study was to examine the impact of 5xFASD on the brain at two developmental stages, postnatal day (P) 30 and embryonic day (E) 17.5. Female C57BL/6 mice were fed a control diet or 5xFASD for 1 month before mating. Diets were maintained throughout the pregnancy and lactation until P30 or during pregnancy until E17.5. The 5xFASD led to sex-specific transcription changes in a P30 cerebral cortex and E17.5 cerebrum, with microarrays showing a total of 1003 and 623 changes, respectively. Enhanced mRNA degradation was observed in E17.5 cerebrum. Expression changes of genes involved in neurotransmission, neuronal growth and development, and angiogenesis were verified by qRT-PCR; 12 and 15 genes were verified at P30 and E17.5, respectively. Hippocampal collagen staining suggested decreased vessel density in FASD male embryos. This study provides insight into the mechanisms of neurobehavioral alterations and highlights potential deleterious consequences of moderate folate oversupplementation during pregnancy