Biology subjects

Freund, A.

Publications and source records attributed to Freund, A..

8 recordsLinked to original sources

bioRxiv2023

Interactions between the gut microbiome, dietary restriction, and aging in genetically diverse mice

The intestinal microbiome changes with age, but the causes and consequences of microbiome aging remain unclear. Furthermore, the gut microbiome has been proposed to mediate the benefit of lifespan- extending interventions such as dietary restriction, but this hypothesis warrants further exploration. Here, by analyzing 2997 metagenomes collected longitudinally from 913 deeply phenotyped, genetically diverse mice, we provide new insights into the interplay between the microbiome, aging, dietary restriction, host genetics, and a wide range of health parameters. First, we find that microbiome uniqueness increases with age across datasets and species. Moreover, age-associated changes are better explained by cumulative exposure to stochastic events (neutral theory) than by the influence of an aging host (selection theory). Second, we unexpectedly find that the majority of microbiome features are significantly heritable and that the amount of variation explained by host genetics is as large as that of aging and dietary restriction. Third, we find that the intensity of dietary restriction parallels the extent of microbiome changes and that dietary restriction does not rejuvenate the microbiome. Lastly, we find that the microbiome is significantly associated with multiple health parameters -- including body composition, immune parameters, and frailty -- but not with lifespan. In summary, this large and multifaceted study sheds light on the factors influencing the microbiome and aspects of host physiology modulated by the microbiome.

microbiology↗

bioRxiv2023

Regulators of health and lifespan extension in genetically diverse mice on dietary restriction

Caloric restriction (CR) delays aging and extends healthy lifespan in multiple species. Alternative forms of dietary restriction (DR) such as intermittent fasting (IF) have drawn significant interest as a more sustainable regimen, but the landscape of longevity-promoting dietary interventions remains largely unexplored. Identifying the most robust, efficacious, and experimentally tractable modes of DR is key to better understanding and implementing effective longevity interventions for human healthspan. To that end, we have performed an extensive assessment of DR interventions, investigating the effects of graded levels of CR (20% and 40%) and IF (1 day and 2 days of fasting per week) on the health and survival of 960 genetically diverse female mice. All interventions extended lifespan, although only CR significantly reduced the mortality doubling time. Notably, IF did not extend lifespan in mice with high pre-intervention bodyweight. We carried out extensive phenotyping to determine the health effects of long-term DR and to better understand the mechanisms driving within-diet heterogeneity in lifespan. The top within-diet predictor of lifespan was the ability of mice to maintain bodyweight through periods of handling, an indicator of stress resilience. Additional predictors of long lifespan include specific changes in immune cells, red blood cell distribution width (RDW), and retention of adiposity in late life. We found that lifespan is heritable (h2 = 0.24), and that genetic background has a larger influence on lifespan than dietary interventions. We identified a significant association for lifespan and RDW on chromosome 18 that explained 4.3% of the diet-adjusted variation in lifespan. Diet-induced changes on metabolic traits, although beneficial, were relatively poor predictors of lifespan, arguing against the long-standing notion that DR works by counteracting the negative effects of obesity. These findings indicate that improving health and extending lifespan are not synonymous and that metabolic parameters may be inappropriate endpoints for evaluating aging interventions in preclinical models and clinical trials.

genetics↗

bioRxiv2022

Life-long Dietary Restrictions have Negligible or Damaging Effects on Late-life Cognitive Performance: A Key Role for Genetics in Outcomes

Several studies report that caloric restriction (CR) or intermittent fasting (IF) can improve cognition, while others report limited or no cognitive benefits. Here, we compare the effects of 20% CR, 40% CR, 1-day IF, and 2-day IF feeding paradigms to ad libitum controls (AL) on Y-maze working memory and contextual fear memory (CFM) in a large population of Diversity Outbred mice that model the genetic diversity of humans. While CR and IF interventions improve lifespan, we observed no enhancement of working memory or CFM in mice on these feeding paradigms, and report 40% CR to be damaging in the context of long-term memory. Using Quantitative Trait Loci mapping, we identified the gene Slc16a7 to be associated with late-life long-term memory outcomes in mice on lifespan promoting feeding paradigms. Limited utility of dieting and fasting on memory in mice that recapitulate genetic diversity in the human population highlights the need for anti-aging therapeutics that promote cognitive function, with a neuronal monocarboxylate transporter encoded by Slc16a7 highlighted as novel target.

animal behavior and cognition↗

bioRxiv2021

Automated, high-dimensional evaluation of physiological aging and resilience in outbred mice

Behavior and physiology are essential readouts in many studies but have not benefited from the high-dimensional data revolution that has transformed molecular and cellular phenotyping. To address this, we developed an approach that combines commercially available automated phenotyping hardware with a systems biology analysis pipeline to generate a high-dimensional readout of mouse behavior/physiology, as well as intuitive and health-relevant summary statistics (resilience and biological age). We used this platform to longitudinally evaluate aging in hundreds of outbred mice across an age range from 6 months to 3.4 years. In contrast to the assumption that aging can only be measured at the limits of animal ability via challenge-based tasks, we observed widespread physiological and behavioral aging starting in early life. Using network connectivity analysis, we found that organism-level resilience exhibited an accelerating decline with age that was distinct from the trajectory of individual phenotypes. We developed a method, Combined Aging and Survival Prediction of Aging Rate (CASPAR), for jointly predicting chronological age and survival time and showed that the resulting model is able to predict both variables simultaneously, a behavior that is not captured by separate age and mortality prediction models. This study provides a uniquely high-resolution view of physiological aging in mice and demonstrates that systems-level analysis of physiology provides insights not captured by individual phenotypes. The approach described here allows aging, and other processes that affect behavior and physiology, to be studied with sophistication and rigor.

systems biology↗

bioRxiv2021

Revisiting the Hayflick Limit: Insights from an Integrated Analysis of Changing Transcripts, Proteins, Metabolites and Chromatin

The process wherein dividing cells exhaust proliferative capacity and enter into replicative senescence has become a prominent model for cellular aging in vitro. Despite decades of study, this cellular state is not fully understood in culture and even much less so during aging. Here, we revisit Leonard Hayflicks original observation of replicative senescence in WI-38 human lung fibroblasts equipped with a battery of modern techniques including RNA-seq, single cell RNA-seq, proteomics, metabolomics, and ATAC-seq. We find evidence that the transition to a senescent state manifests early, increases gradually, and corresponds to a concomitant global increase in DNA accessibility in nucleolar and lamin associated domains. Furthermore, we demonstrate that senescent WI-38 cells acquire a striking resemblance to myofibroblasts in a process similar to the epithelial to mesenchymal transition (EMT) that is regulated by the transcription factors YAP1/TEAD1 and TGF-{beta}2. Lastly, we show that verteporfin inhibition of YAP1/TEAD1 activity in aged WI-38 cells robustly attenuates this gene expression program.

genomics↗

bioRxiv2021

Intermittent fasting and caloric restriction interact with genetics to shape physiological health in mice

Dietary interventions can dramatically affect physiological health and organismal lifespan. The degree to which organismal health is improved depends upon genotype and the severity of dietary intervention, but neither the effects of these factors, nor their interaction, have been quantified in an outbred population. Moreover, it is not well understood what physiological changes occur shortly after dietary change and how these may affect the health of early adulthood population. In this article, we investigated the effect of six month exposure of either caloric restriction or intermittent fasting on a broad range of physiological traits in 960 one year old Diversity Outbred mice. We found caloric restriction and intermittent fasting affected distinct aspects of physiology and neither the magnitude nor the direction (beneficial or detrimental) of effects were concordant with the severity of the intervention. In addition to the effects of diet, genetic variation significantly affected 31 of 36 traits (heritabilties ranged from 0.04-0.65). We observed significant covariation between many traits that was due to both diet and genetics and quantified these effects with phenotypic and genetic correlations. We genetically mapped 16 diet-independent and 2 diet-dependent significant quantitative trait loci, both of which were associated with cardiac physiology. Collectively, these results demonstrate the degree to which diet and genetics interact to shape the physiological health of early adult-hood mice following six months of dietary intervention.

genetics↗

bioRxiv2020

Age and diet shape the genetic architecture of body weight in Diversity Outbred mice

AO_SCPLOWBSTRACTC_SCPLOWUnderstanding how genetic variation shapes an age-dependent complex trait relies on accurate quantification of both the additive genetic effects and genotype-environment interaction effects in an age-dependent manner. We used a generalization of the linear mixed model to quantify diet-dependent genetic contributions to body weight and growth rate measured from early development through adulthood of 960 Diversity Outbred female mice subjected to five dietary interventions. We observed that heritability of body weight remained substantially high (h2 {approx} 0.8) throughout adulthood under the 40% calorie restriction diet, while heritability, although still appreciably high, declined with age under all other dietary regimes. We identified 14 loci significantly associated with body weight in an age-dependent manner and 19 loci that contribute to body weight in an age- and diet-dependent manner. We found the effect of body weight alleles to be dynamic with respect to genomic background, age, and diet, identifying the scope of pleiotropy and several instances of allelic heterogeneity. In many cases, we fine-mapped these loci to narrow genomic intervals containing a few genes and impute putative functional variants from the genome sequence of the DO founders. Of the loci associated with body weight in a diet-dependent manner, many have been previously linked to neurological function and behavior in mice or humans. These results enable us to more fully understand the dynamics of the genetic architecture of body weight with age and in response to different dietary interventions, and to predict the effectiveness of dietary intervention on overall health in distinct genetic backgrounds.

genetics↗

bioRxiv2020

Pharmacological inhibition of longevity regulator PAPP-A restrains mesenchymal stromal cell activity

Reducing insulin-like growth factor (IGF) signaling is one of the best conserved and characterized mechanisms to extend longevity. Pregnancy associated plasma protein A (PAPP-A) is a secreted metalloprotease that increases IGF availability by cleaving IGF binding proteins. PAPP-A inhibition reduces local IGF signaling, limits the progression of multiple age-related diseases, and extends lifespan, but the mechanisms behind these pleiotropic effects remains unknown. Here, we developed and utilized a PAPP-A neutralizing antibody to discover that adulthood inhibition of this protease reduced collagen and extracellular matrix (ECM) gene expression in multiple tissues in mice. Using bone marrow to explore this effect, we identified mesenchymal stromal cells (MSCs) as the source of PAPP-A and primary responders to PAPP-A inhibition. Short-term treatment with anti-PAPP-A reduced IGF signaling in MSCs, altered MSC expression of collagen/ECM, and decreased MSC number. This affected MSC-dependent functions, decreasing myelopoiesis and osteogenesis. Our data demonstrate that PAPP-A inhibition reduces the activity and number of IGF-dependent mesenchymal progenitor cells and their differentiated progeny, and that this reduction leads to functional changes at the tissue level. MSC-like cells are present in virtually all tissues, and aberrant collagen and ECM production from mesenchymal cells drives aspects of aging and age-related diseases, thus this may be a mechanism by which PAPP-A deficiency enhances lifespan and healthspan. SummaryInhibition of PAPP-A, a regulator of IGF signaling, decreases multi-tissue collagen and extracellular matrix gene expression and modulates mesenchymal stromal cell activity in murine bone marrow.

physiology↗