Multiomics profiling of the impact of an angiotensin (1-7)-expressing probiotic combined with exercise training in aged male rats.

Angiotensin (1-7) [Ang (1-7)] is an active heptapeptide of the noncanonical arm of the renin-angiotensin system that modulates molecular signaling pathways associated with vascular and cellular inflammation, vasoconstriction, and fibrosis. Preclinical evidence suggests that Ang (1-7) is a promising therapeutic target that may ameliorate physical and cognitive function in late life. However, treatment pharmacodynamics limits its clinical applicability. Therefore, this study explored the underlying mechanisms altered by a genetically modified probiotic (GMP) that expresses Ang (1-7) combined with and without exercise training in an aging male rat model as a potential adjunct strategy to exercise training to counteract the decline of physical and cognitive function. We evaluated cross-tissue (prefrontal cortex, hippocampus, colon, liver, and skeletal muscle) multi-omics responses. After 12 wk of intervention, the 16S mRNA microbiome analysis revealed a main effect of probiotic treatment within- and between groups. The probiotic treatment enhanced α diversity (Inverse Simpson (F[2,56] = 4.44; P = 0.02); Shannon-Wiener (F[2,56] = 4.27; P = 0.02)) and ß-diversity (F[2,56] = 2.66; P = 0.01) among rats receiving our GMP. The analysis of microbes' composition revealed three genera altered by our GMP (Enterorhabdus, Muribaculaceae unclassified, and Faecalitalea). The mRNA multi-tissue data analysis showed that our combined intervention upregulated neuroremodeling pathways on prefrontal cortex (i.e., 140 genes), inflammation gene expression in the liver (i.e., 63 genes), and circadian rhythm signaling on skeletal muscle. Finally, the integrative network analysis detected different communities of tightly (|r| > 0.8 and P < 0.05) correlated metabolites, genera, and genes in these tissues.NEW & NOTEWORTHY This manuscript uses a multiomics approach (i.e., microbiome, metabolomics, and transcriptomics) to explore the underlying mechanisms driven by a genetically modified probiotic (GMP) designed to express angiotensin (1-7) combined with moderate exercise training in an aged male rat model. After 12 wk of intervention, our findings suggest that our GMP enhanced gut microbial diversity while exercise training altered the transcriptional response in relevant neuroremodeling genes, inflammation, and circadian rhythm signaling pathways in an aging animal model.

Angiotensin (1-7) Delivered Orally via Probiotic in Combination With Exercise: Sex-Dependent Influence on Health Span.

Age-related declines in physical and cognitive function can have tremendous, negative impacts on health span and quality of life. Therefore, we investigated the potential of utilizing a probiotic treatment to target the renin-angiotensin system (RAS) in conjunction with moderate exercise to ameliorate age-related declines in cognitive and physical function in aged rats. Herein we utilized a genetically modified angiotensin (1-7), which activates a "complementary" arm of the RAS through binding Mas (AT7) receptors. This process induces several beneficial physiologic effects, including decreased inflammation and enhanced physical/cognitive function. Thus, in this short research report, we suggest the efficacy of this Ang(1-7) releasing Lactobacillus paracasei (LPA) as either an alternative strategy to exercise, or more likely as an adjuvant to moderate exercise, for the prevention of both physical and cognitive decline especially in female rats.

Twelve Months of Time-Restricted Feeding Improves Cognition and Alters Microbiome Composition Independent of Macronutrient Composition.

Declining health, gut dysbiosis, and cognitive impairments are hallmarks of advanced age. While caloric restriction is known to robustly extend the healthspan and alter gut microbiome composition, it is difficult maintain. Time-restricted feeding or changes in dietary macronutrient composition could be feasible alternatives for enhancing late life cognitive and physical health that are easier to comply with for extended periods of time. To investigate this possibility, 8-month-old rats were placed on time-restricted feeding with a ketogenic or micronutrient- and calorically matched control diet for 13 months. A third group of rats was permitted to eat standard chow ad libitum during this time. At 22 months, all rats were tested on a biconditional association task and fecal samples were collected for microbiome composition analysis. Regardless of dietary composition, time-restricted-fed rats had better cognitive performance than ad libitum-fed rats. This observation could not be accounted for by differences in motivation, procedural or sensorimotor impairments. Additionally, there were significant differences in gut microbiome diversity and composition between all diet conditions. Allobaculum abundance was associated with cognitive task performance, indicating a link between gut health and cognitive outcomes in aged subjects. Overall, time restricted feeding had the largest influence on cognitive performance in aged rats.

Preserving independence among under-resourced older adults in the Southeastern United States: existing barriers and potential strategies for research.

Disability prevention and preservation of independence is crucial for successful aging of older adults. To date, relatively little is known regarding disparities in independent aging in a disadvantaged older adult population despite widely recognized health disparities reported in other populations and disciplines. In the U.S., the Southeastern region also known as "the Deep South", is an economically and culturally unique region ravaged by pervasive health disparities - thus it is critical to evaluate barriers to independent aging in this region along with strategies to overcome these barriers. The objective of this narrative review is to highlight unique barriers to independent aging in the Deep South and to acknowledge gaps and potential strategies and opportunities to fill these gaps. We have synthesized findings of literature retrieved from searches of computerized databases and authoritative texts. Ultimately, this review aims to facilitate discussion and future research that will help to address the unique challenges to the preservation of independence among older adults in the Deep South region.

Influence of Aging, Macronutrient Composition and Time-Restricted Feeding on the Fischer344 x Brown Norway Rat Gut Microbiota.

Both ketogenic diets (KD) and time-restricted feeding (TRF) regimens have the ability to influence several parameters of physical health, including gut microbiome composition and circulating cytokine concentration. Moreover, both of these dietary interventions prevent common impairments associated with the aging process. However, significantly altering macronutrient intake, which is required for a KD, may be unappealing to individuals and decrease compliance to dietary treatments. In contrast to a KD, TRF allows individuals to continue eating the foods they are used to, and only requires a change in the time of day at which they eat. Therefore, we investigated both a KD and a diet with a more Western-like macronutrient profile in the context of TRF, and compared both diets to animals allowed access to standard chow ad libitum in young adult and aged rats. While limited effects on cytokine levels were observed, both methods of microbiome analysis (16S sequencing and metagenomics) indicate that TRF and KDs significantly altered the gut microbiome in aged rats. These changes were largely dependent on changes to feeding paradigm (TRF vs. ad libitum) alone regardless of macronutrient content for many gut microbiota, but there were also macronutrient-specific changes. Specifically, functional analysis indicates significant differences in several pathways, including those involved in the tricarboxylic acid (TCA) cycle, carbohydrate metabolism and neurodegenerative disease. These data indicate that age- and disease-related gut dysbiosis may be ameliorated through the use of TRF with both standard diets and KDs.

Targeting whole body metabolism and mitochondrial bioenergetics in the drug development for Alzheimer's disease.

Aging is by far the most prominent risk factor for Alzheimer's disease (AD), and both aging and AD are associated with apparent metabolic alterations. As developing effective therapeutic interventions to treat AD is clearly in urgent need, the impact of modulating whole-body and intracellular metabolism in preclinical models and in human patients, on disease pathogenesis, have been explored. There is also an increasing awareness of differential risk and potential targeting strategies related to biological sex, microbiome, and circadian regulation. As a major part of intracellular metabolism, mitochondrial bioenergetics, mitochondrial quality-control mechanisms, and mitochondria-linked inflammatory responses have been considered for AD therapeutic interventions. This review summarizes and highlights these efforts.

Bridging the Gap: A Geroscience Primer for Neuroscientists With Potential Collaborative Applications.

While neurodegenerative diseases can strike at any age, the majority of afflicted individuals are diagnosed at older ages. Due to the important impact of age in disease diagnosis, the field of neuroscience could greatly benefit from the many of the theories and ideas from the biology of aging-now commonly referred as geroscience. As discussed in our complementary perspective on the topic, there is often a "silo-ing" between geroscientists who work on understanding the mechanisms underlying aging and neuroscientists who are studying neurodegenerative diseases. While there have been some strong collaborations between the biology of aging and neuroscientists, there is still great potential for enhanced collaborative effort between the 2 fields. To this end, here, we review the state of the geroscience field, discuss how neuroscience could benefit from thinking from a geroscience perspective, and close with a brief discussion on some of the "missing links" between geroscience and neuroscience and how to remedy them. Notably, we have a corresponding, concurrent review from the neuroscience perspective. Our overall goal is to "bridge the gap" between geroscience and neuroscience such that more efficient, reproducible research with translational potential can be conducted.

Probiotic Releasing Angiotensin (1-7) in a Drosophila Model of Alzheimer's Disease Produces Sex-Specific Effects on Cognitive Function.

BACKGROUND: While extensive research on the brain has failed to identify effective therapies, using probiotics to target the gut microbiome has shown therapeutic potential in Alzheimer's disease (AD). Genetically modified probiotics (GMP) are a promising strategy to deliver key therapeutic peptides with high efficacy and tissue specificity. Angiotensin (Ang)-(1-7) levels inversely correlate to AD severity, but its administration is challenging. Our group has successfully established a GMP-based method of Ang-(1-7) delivery. OBJECTIVE: Since Drosophila represents an excellent model to study the effect of probiotics on complex disorders in a high throughput manner, we tested whether oral supplementation with Lactobacillus paracasei releasing Ang-(1-7) (LP-A) delays memory loss in a Drosophila AD model. METHODS: Flies overexpressing the human amyloid-ß protein precursor and its ß-site cleaving enzyme in neurons were randomized to receive four 24-h doses of Lactobacillus paracasei alone (LP), LP-A or sucrose over 14 days. Memory was assessed via an aversive phototaxic suppression assay. RESULTS: Optimal dilution,1:2, was determined based on palatability. LP-A improved memory in trained AD males but worsened cognition in AD females. LP-supplementation experiments confirmed that Ang-(1-7) conferred additional cognitive benefits in males and was responsible for the deleterious cognitive effects in females. Sex-specific differences in the levels of angiotensin peptides and differential activation of the kynurenine pathway of tryptophan metabolism in response to supplementation may underlie this male-only therapeutic response. CONCLUSION: In summary, LP-A ameliorated the memory deficits of a Drosophila AD model, but effects were sex-specific. Dosage optimization may be required to address this differential response.

Interactive Effects of Enalapril Administration and Novel HIIT Wheel-Bed Training in Aged Rats.

INTRODUCTION: Growing research suggests that aerobic high-intensity interval training (HIIT) improves cardiovascular function and physical performance compared with moderate intensity continuous training (MICT). However relatively few animal models of HIIT are available to inform about the benefits of this exercise-particularly among older animals. In addition, there is little evidence for how HIIT training interacts with adjuvant pharmacological therapies known to enhance the impact of MCIT in older individuals such as Angiotensin Converting Enzyme (ACE) Inhibitors. PURPOSE: The aim of the present study was to establish a HIIT protocol in aged rats based on forced running wheel-bed, and to subsequently (1) establish the feasibility of the HIIT protocol in a proof-of-concept study evaluating interactions between HIIT and (2) the result of combining HIIT + ACE inhibitor treatment using the ACE inhibitor enalapril. METHODS: Two groups of rats were used in this study. The feasibility of using wheel-bed for HIIT training was tested in group one (15- and 30-month-old male rats). In the second group, 37 24-month-old Fisher 344 × Brown Norway male rats were randomly divided into four subgroups: control, enalapril, HIIT training group, and HIIT training combined with enalapril administration. The training and administration lasted for 4 weeks. After the intervention, locomotor activity, exercise tolerance, and grip strength were tested. RESULTS: Our feasibility study suggested that middle-aged and aged rats were able to successfully complete the HIIT training. In our intervention study, HIIT training alone, regardless of adjuvant enalapril intervention, did raise treadmill exercise tolerance vs. the sedentary condition. Measures of healthspan were not negatively impacted by HIIT training. CONCLUSION: The novel HIIT protocol based on forced running wheel-bed was successfully employed in aged rats. We conclude that future studies should compare the results and of multi-modal intervention strategies which include both HIIT and MICT in combination with adjuvant therapies such as enalapril to improve exercise tolerance and other global indices of healthspan.

Angiotensin (1-7) Expressing Probiotic as a Potential Treatment for Dementia.

Increasing life expectancies are unfortunately accompanied by increased prevalence of Alzheimer's disease (AD). Regrettably, there are no current therapeutic options capable of preventing or treating AD. We review here data indicating that AD is accompanied by gut dysbiosis and impaired renin angiotensin system (RAS) function. Therefore, we propose the potential utility of an intervention targeting both the gut microbiome and RAS as both are heavily involved in proper CNS function. One potential approach which our group is currently exploring is the use of genetically-modified probiotics (GMPs) to deliver therapeutic compounds. In this review, we specifically highlight the potential utility of utilizing a GMP to deliver Angiotensin (1-7), a beneficial component of the renin-angiotensin system with relevant functions in circulation as well as locally in the gut and brain.

University of Alabama at Birmingham Nathan Shock Center: comparative energetics of aging.

The UAB Nathan Shock Center focuses on comparative energetics and aging. Energetics, as defined for this purpose, encompasses the causes, mechanisms, and consequences of the acquisition, storage, and use of metabolizable energy. Comparative energetics is the study of metabolic processes at multiple scales and across multiple species as it relates to health and aging. The link between energetics and aging is increasingly understood in terms of dysregulated mitochondrial function, altered metabolic signaling, and aberrant nutrient responsiveness with increasing age. The center offers world-class expertise in comprehensive, integrated energetic assessment and analysis from the level of the organelle to the organism and across species from the size of worms to rats as well as state-of-the-art data analytics. The range of services offered by our three research cores, (1) The Organismal Energetics Core, (2) Mitometabolism Core, and (3) Data Analytics Core, is described herein.

Maintaining a scientific community while social distancing.

The "Aging Science Talks: Science for the Community" daily online seminar series was established in reaction to the cancellation of a myriad of regional, national, and international meetings focused on the biology of aging due to the COVID-19 pandemic. The inability to attend scientific meetings has far-reaching implications for our field, as we lose the ability to 1) disseminate both published and non-published data through talks and posters; 2) network and establish new collaborations to produce innovative science in the aging field; and 3) continue the career development of early career researchers (ECRs). Through these virtual seminars, we hope to offset the negative effects of these canceled meetings. We established the program rapidly using a "lean" approach, making use of existing technologies broadly available at academic institutions. Here, we provide an initial description of how this program was developed and implemented. We discuss advantages and limitations of this approach, including "real-time" participation and the creation of an on/off-line community of inquiry (CoI). In the future, we hope to formally evaluate the success of this program in building engagement, creating a community, and enhancing the development of ECRs, and to capture metrics associated with the continued progress of science. Our approach to building a CoI may be applied across multiple scientific disciplines during this time of uncertainty, and may offer a valuable example of how to continue to advance science during pandemics or similar events.

Angiotensin (1-7) delivered orally via probiotic, but not subcutaneously, benefits the gut-brain axis in older rats.

To (1) investigate the efficacy of multiple doses of an orally delivered probiotic bacteria Lactobacillus paracasei (LP) modified to express angiotensin (1-7) (LP-A) in altering physiologic parameters relevant to the gut-brain axis in older rats and to (2) compare this strategy with subcutaneous delivery of synthetic Ang(1-7) peptide on circulating Ang(1-7) concentrations and these gut-brain axis parameters. Male 24-month-old F344BN rats received oral gavage of LP-A, or subcutaneous injection of Ang(1-7) for 0×, 1×, 3×, or 7×/week over 4 weeks. Circulating RAS analytes, inflammatory cytokines, and tryptophan and its downstream metabolites were measured by ELISA, electrochemiluminescence, and LC-MS respectively. Microbiome taxonomic analysis of fecal samples was performed via 16S-based PCR. Inflammatory and tryptophan-related mRNA expression was measured in colon and pre-frontal cortex. All dosing regimens of LP-A induced beneficial changes in fecal microbiome including overall microbiota community structure and α-diversity, while the 3×/week also significantly increased expression of the anti-inflammatory species Akkermansia muciniphila. The 3×/week also increased serum serotonin and the neuroprotective analyte 2-picolinic acid. In the colon, LP-A increased quinolinate phosphoribosyltransferase expression (1×/week) and increased kynurenine aminotransferase II (1× and 3×/week) mRNA expression. LP-A also significantly reduced neuro-inflammatory gene expression in the pre-frontal cortex (3×/week: COX2, IL-1ß, and TNFα; 7×/week: COX2 and IL-1ß). Subcutaneous delivery of Ang(1-7) increased circulating Ang(1-7) and reduced angiotensin II, but most gut-brain parameters were unchanged in response. Oral-but not subcutaneous-Ang(1-7) altered physiologic parameters related to gut-brain axis, with the most effects observed in 3×/week oral dosing regimen in older rats.

Crosstalk Between the Gut Microbiome and Bioactive Lipids: Therapeutic Targets in Cognitive Frailty.

Cognitive frailty is a geriatric condition defined by the coexistence of cognitive impairment and physical frailty. This "composite" aging phenotype is associated with a higher risk of several adverse health-related outcomes, including dementia. In the last decade, cognitive frailty has gained increased attention from the scientific community that has focused on understanding the clinical impact and the physiological and pathological mechanisms of development and on identifying preventive and/or rehabilitative therapeutic interventions. The emergence of gut microbiome in neural signaling increased the interest in targeting the gut-brain axis as a modulation strategy. Multiple studies on gastroenteric, metabolic, and neurodegenerative diseases support the existence of a wide bidirectional communication network of signaling mediators, e.g., bioactive lipids, that can modulate inflammation, gut permeability, microbiota composition, and the gut-brain axis. This crosstalk between the gut-brain axis, microbiome, and bioactive lipids may emerge as the basis of a promising therapeutic strategy to counteract cognitive frailty. In this review, we summarize the evidence in the literature regarding the link between the gut microbiome, brain, and several families of bioactive lipids. In addition, we also explore the applicability of several bioactive lipid members as a potential routes for therapeutic interventions to combat cognitive frailty.

Bring Back the Rat!

As 2020 is "The Year of the Rat" in the Chinese astrological calendar, it seems an appropriate time to consider whether we should bring back the laboratory rat to front-and-center in research on the basic biology of mammalian aging. Beginning in the 1970s, aging research with rats became common, peaking in 1992 but then declined dramatically by 2018 as the mouse became preeminent. The purpose of this review is to highlight some of the historical contributions as well as current advantages of the rat as a mammalian model of human aging, because we suspect at least a generation of researchers is no longer aware of this history or these advantages. Herein, we compare and contrast the mouse and rat in the context of several biological domains relevant to their use as appropriate models of aging: phylogeny/domestication, longevity interventions, pathology/physiology, and behavior/cognition. It is not the goal of this review to give a complete characterization of the differences between mice and rats, but to provide important examples of why using rats as well as mice is important to advance our understanding of the biology of aging.

Therapeutic Delivery of Ang(1-7) via Genetically Modified Probiotic: A Dosing Study.

In recent years a number of beneficial health effects have been ascribed to the renin-angiotensin system (RAS) that extend beyond lowering blood pressure, primarily mediated via the angiotensin-converting enzyme-2 (ACE2)/angiotensin (1-7) or Ang(1-7)/MAS receptor axis. Moreover, once thought as merely a systemic effector, RAS components exist within tissues. The highest tissue concentrations of ACE2 mRNA are located in the gut making it an important target for altering RAS function. Indeed, genetically engineered recombinant probiotics are promising treatment strategies offering delivery of therapeutic proteins with precision. An Ang(1-7) secreting Lactobacillus paracasei (LP) or LP-A has been described for regulation of diabetes and hypertension; however, we are the first to the best of our knowledge to propose this paradigm as it relates to aging. In this Research Practice manuscript, we provide proof of concept for using this technology in a well-characterized rodent model of aging: the Fisher344 x Brown Norway Rat (F344BN). Our primary findings suggest that LP-A increases circulating levels of Ang(1-7) both acutely and chronically (after 8 or 28 treatment days) when administered 3× or 7×/week over 4 weeks. Our future preclinical studies will explore the impact of this treatment on gut and other age-sensitive distal tissues such as brain and muscle.

The Gut Microbiome as a Therapeutic Target for Cognitive Impairment.

Declining cognitive functions in older individuals have enormous emotional, clinical, and public health consequences. Thus, therapeutics for preserving function and keeping older adults living independently are imperative. Aging is associated dysbiosis, defined as a loss of number and diversity in gut microbiota, which has been linked with various aspects of cognitive functions. Therefore, the gut microbiome has the potential to be an important therapeutic target for symptoms of cognitive impairment. In this review, we summarize the current literature regarding the potential for gut-targeted therapeutic strategies for prevention/treatment of the symptoms of cognitive impairment. Specifically, we discuss four primary therapeutic strategies: wild-type and genetically modified probiotics, fecal microbiota transplantation, physical exercise, and high-fiber diets and specifically link these therapies to reducing inflammation. These strategies may hold promise as treatment paradigm symptoms related to cognitive impairment.