Bifidobacteria-mediated immune system imprinting early in life.

Immune-microbe interactions early in life influence the risk of allergies, asthma, and other inflammatory diseases. Breastfeeding guides healthier immune-microbe relationships by providing nutrients to specialized microbes that in turn benefit the host's immune system. Such bacteria have co-evolved with humans but are now increasingly rare in modern societies. Here we show that a lack of bifidobacteria, and in particular depletion of genes required for human milk oligosaccharide (HMO) utilization from the metagenome, is associated with systemic inflammation and immune dysregulation early in life. In breastfed infants given Bifidobacterium infantis EVC001, which expresses all HMO-utilization genes, intestinal T helper 2 (Th2) and Th17 cytokines were silenced and interferon ß (IFNß) was induced. Fecal water from EVC001-supplemented infants contains abundant indolelactate and B. infantis-derived indole-3-lactic acid (ILA) upregulated immunoregulatory galectin-1 in Th2 and Th17 cells during polarization, providing a functional link between beneficial microbes and immunoregulation during the first months of life.

Time of day determines postexercise metabolism in mouse adipose tissue.

The circadian clock is a cell-autonomous transcription-translation feedback mechanism that anticipates and adapts physiology and behavior to different phases of the day. A variety of factors including hormones, temperature, food-intake, and exercise can act on tissue-specific peripheral clocks to alter the expression of genes that influence metabolism, all in a time-of-day dependent manner. The aim of this study was to elucidate the effects of exercise timing on adipose tissue metabolism. We performed RNA sequencing on inguinal adipose tissue of mice immediately following maximal exercise or sham treatment at the early rest or early active phase. Only during the early active phase did exercise elicit an immediate increase in serum nonesterified fatty acids. Furthermore, early active phase exercise increased expression of markers of thermogenesis and mitochondrial proliferation in inguinal adipose tissue. In vitro, synchronized 3T3-L1 adipocytes showed a timing-dependent difference in Adrb2 expression, as well as a greater lipolytic activity. Thus, the response of adipose tissue to exercise is time-of-day sensitive and may be partly driven by the circadian clock. To determine the influence of feeding state on the time-of-day response to exercise, we replicated the experiment in 10-h-fasted early rest phase mice to mimic the early active phase metabolic status. A 10-h fast led to a similar lipolytic response as observed after active phase exercise but did not replicate the transcriptomic response, suggesting that the observed changes in gene expression are not driven by feeding status. In conclusion, acute exercise elicits timing-specific effects on adipose tissue to maintain metabolic homeostasis.

Contraction influences Per2 gene expression in skeletal muscle through a calcium-dependent pathway.

KEY POINTS: Exercising at different times of day elicits different effects on exercise performance and metabolic health. However, the specific signals driving the observed time-of-day specific effects of exercise have not been fully identified. Exercise influences the skeletal muscle circadian clock, although the relative contribution of muscle contraction and extracellular signals is unknown. Here, we show that contraction acutely increases the expression of the core circadian clock gene Period Circadian Regulator 2 (Per2) and phase-shifts Per2 rhythmicity in muscle cells. This contraction effect on core clock genes is mediated through a calcium-dependant mechanism; The results obtained in the present study suggest that a proportion of the ability of exercise to entrain the skeletal muscle clock is driven directly by muscle contraction. Contraction interventions may be used to mimic some time-of-day specific effects of exercise on metabolism and muscle performance. ABSTRACT: Exercise entrains the central and peripheral circadian clocks, although the mechanism by which exercise modulates expression of skeletal muscle clock genes is unclear. The present study aimed to determine whether skeletal muscle contraction alone could directly influence circadian rhythmicity and uncover the underlying mechanism by which contraction modulates clock gene expression. We investigated the expression of core clock genes in human skeletal muscle after acute exercise, as well as following in vitro contraction in mouse soleus muscle and cultured C2C12 skeletal muscle myotubes. Additionally, we interrogated the molecular pathways by which skeletal muscle contraction could influence clock gene expression. Contraction acutely increased the expression of the core circadian clock gene Period Circadian Regulator 2 (Per2) and phase-shifted Per2 rhythmicity in C2C12 myotubes in vitro. Further investigation revealed that pharmacologically increasing cytosolic calcium concentrations by ionomycin treatment mimicked the effect of contraction on Per2 expression. Similarly, treatment with a calcium channel blocker, nifedipine, blocked the effect of electric pulse stimulation-induced contraction on Per2 expression. Increased calcium influx from contraction lead to binding of the phosphorylated form of cAMP response element-binding protein (CREB) to the Per2 promoter, suggesting a role of CREB in contraction-induced Per2 transcription. Thus, by dissociating the effect of muscle contraction alone from the whole effect of exercise, our investigations indicate that a proportion of the ability of exercise to entrain the skeletal muscle clock is driven directly by contraction.

Indole-3-lactic acid associated with Bifidobacterium-dominated microbiota significantly decreases inflammation in intestinal epithelial cells.

BACKGROUND: Bifidobacterium longum subsp. infantis (B. infantis) is a commensal bacterium that colonizes the gastrointestinal tract of breast-fed infants. B. infantis can efficiently utilize the abundant supply of oligosaccharides found in human milk (HMO) to help establish residence. We hypothesized that metabolites from B. infantis grown on HMO produce a beneficial effect on the host. RESULTS: In a previous study, we demonstrated that B. infantis routinely dominated the fecal microbiota of a breast fed Bangladeshi infant cohort (1). Characterization of the fecal metabolome of binned samples representing high and low B. infantis populations from this cohort revealed higher amounts of the tryptophan metabolite indole-3-lactic acid (ILA) in feces with high levels of B. infantis. Further in vitro analysis confirmed that B. infantis produced significantly greater quantities of the ILA when grown on HMO versus lactose, suggesting a growth substrate relationship to ILA production. The direct effects of ILA were assessed in a macrophage cell line and intestinal epithelial cell lines. ILA (1-10 mM) significantly attenuated lipopolysaccharide (LPS)-induced activation of NF-kB in macrophages. ILA significantly attenuated TNF-α- and LPS-induced increase in the pro-inflammatory cytokine IL-8 in intestinal epithelial cells. ILA increased mRNA expression of the aryl hydrogen receptor (AhR)-target gene CYP1A1 and nuclear factor erythroid 2-related factor 2 (Nrf2)-targeted genes glutathione reductase 2 (GPX2), superoxide dismutase 2 (SOD2), and NAD(P) H dehydrogenase (NQO1). Pretreatment with either the AhR antagonist or Nrf-2 antagonist inhibited the response of ILA on downstream effectors. CONCLUSIONS: These findings suggest that ILA, a predominant metabolite from B. infantis grown on HMO and elevated in infant stool high in B. infantis, and protects gut epithelial cells in culture via activation of the AhR and Nrf2 pathway.

Screening older Latinos for dementia in the primary care setting.

The purpose was to compare the Spanish language picture version of the Free and Cued Selective Reminding Test with Immediate Recall (pFCSRT+IR) and the Mini Mental State Exam (MMSE) in identifying very mild dementia among Spanish speaking Latino patients. The tests and an independent diagnostic assessment were administered to 112 Latino patients free of medically diagnosed dementia from an urban primary care clinic. Receiver operating characteristic (ROC) curves and the area under the curve (AUC) were used to examine differences in the operating characteristics of the pFCSRT+IR and the MMSE. Cut scores were manipulated to equate sensitivities (specificities) at clinically relevant values to compare differences in specificities (sensitivities) using the Pearson Chi Square test. Youden's index was used to select the optimal cut scores. Twenty-four of the 112 primary care patients (21%) received a research dementia diagnosis, indicating a substantial burden of unrecognized dementia. MMSE scores but not free recall scores were associated with years of education in patients free of dementia. AUC was significantly higher for free recall than for MMSE. Free recall performed significantly better than the MMSE in sensitivity and in specificity. Using optimal cut scores, patients with impaired free recall were 10 times more likely to have dementia than patients with intact recall, and patients with impaired MMSE scores were 4.5 times more likely to have dementia than patients with intact scores. These results suggest that the Spanish language pFCSRT+IR may be an effective tool for dementia screening in educationally diverse Latino primary care populations.

Metabolic plasticity and obesity-associated changes in diurnal postexercise metabolism in mice.

BACKGROUND: Circadian disruption is widespread and increases the risk of obesity. Timing of therapeutic interventions may promote coherent and efficient gating of metabolic processes and restore energy homeostasis. AIM: To characterize the diurnal postexercise metabolic state in mice and to identify the influence of diet-induced obesity on identified outcomes. METHODS: C57BL6/NTac male mice (6 wks of age) were fed a standard chow or high-fat diet for 5 weeks. At week 5, mice were subjected to a 60-min (16 m/min, 5 % incline) running bout (or sham) during the early rest (day) or early active (night) phase. Tissue and serum samples were collected immediately post-exercise (n = 6/group). In vivo glucose oxidation was measured after oral administration of 13C-glucose via 13CO2 exhalation analysis in metabolic cages. Basal and isoproterenol-stimulated adipose tissue lipolysis was assessed ex vivo for 1 h following exercise. RESULTS: Lean mice displayed exercise-timing-specific plasticity in metabolic outcomes, including phase-specificity in systemic glucose metabolism and adipose-tissue-autonomous lipolytic activity depending on time of day. Conversely, obesity impaired temporal postexercise differences in whole-body glucose oxidation, as well as the phase- and exercise-mediated induction of lipolysis in isolated adipose tissue. This obesity-induced alteration in diurnal metabolism, as well as the indistinct response to exercise, was observed concomitant with disruption of core clock gene expression in peripheral tissues. CONCLUSIONS: Overall, high-fat fed obese mice exhibit metabolic inflexibility, which is also evident in the diurnal exercise response. Our study provides physiological insight into exercise timing-dependent aspects in the dynamic regulation of metabolism and the influence of obesity on this biology.

Non-literacy biased, culturally fair cognitive detection tool in primary care patients with cognitive concerns: a randomized controlled trial.

Dementia is often undiagnosed in primary care, and even when diagnosed, untreated. The 5-Cog paradigm, a brief, culturally adept, cognitive detection tool paired with a clinical decision support may reduce barriers to improving dementia diagnosis and care. We performed a randomized controlled trial in primary care patients experiencing health disparities (racial/ethnic minorities and socioeconomically disadvantaged). Older adults with cognitive concerns were assigned in a 1:1 ratio to the 5-Cog paradigm or control. Primary outcome was improved dementia care actions defined as any of the following endpoints within 90 days: new mild cognitive impairment syndrome or dementia diagnoses as well as investigations, medications or specialist referrals ordered for cognitive indications. Groups were compared using intention-to-treat principles with multivariable logistic regression. Overall, 1,201 patients (mean age 72.8 years, 72% women and 94% Black, Hispanic or Latino) were enrolled and 599 were assigned to 5-Cog and 602 to the control. The 5-Cog paradigm demonstrated threefold odds of improvement in dementia care actions over control (odds ratio 3.43, 95% confidence interval 2.32-5.07). No serious intervention-related adverse events were reported. The 5-Cog paradigm improved diagnosis and management in patients with cognitive concerns and provides evidence to promote practice change to improve dementia care actions in primary care.ClinicalTrials.gov: NCT03816644 .

Trigonelline is an NAD+ precursor that improves muscle function during ageing and is reduced in human sarcopenia.

Mitochondrial dysfunction and low nicotinamide adenine dinucleotide (NAD+) levels are hallmarks of skeletal muscle ageing and sarcopenia1-3, but it is unclear whether these defects result from local changes or can be mediated by systemic or dietary cues. Here we report a functional link between circulating levels of the natural alkaloid trigonelline, which is structurally related to nicotinic acid4, NAD+ levels and muscle health in multiple species. In humans, serum trigonelline levels are reduced with sarcopenia and correlate positively with muscle strength and mitochondrial oxidative phosphorylation in skeletal muscle. Using naturally occurring and isotopically labelled trigonelline, we demonstrate that trigonelline incorporates into the NAD+ pool and increases NAD+ levels in Caenorhabditis elegans, mice and primary myotubes from healthy individuals and individuals with sarcopenia. Mechanistically, trigonelline does not activate GPR109A but is metabolized via the nicotinate phosphoribosyltransferase/Preiss-Handler pathway5,6 across models. In C. elegans, trigonelline improves mitochondrial respiration and biogenesis, reduces age-related muscle wasting and increases lifespan and mobility through an NAD+-dependent mechanism requiring sirtuin. Dietary trigonelline supplementation in male mice enhances muscle strength and prevents fatigue during ageing. Collectively, we identify nutritional supplementation of trigonelline as an NAD+-boosting strategy with therapeutic potential for age-associated muscle decline.

Milk oligosaccharide-driven persistence of Bifidobacterium pseudocatenulatum modulates local and systemic microbial metabolites upon synbiotic treatment in conventionally colonized mice.

BACKGROUND: Bifidobacteria represent an important gut commensal in humans, particularly during initial microbiome assembly in the first year of life. Enrichment of Bifidobacterium is mediated though the utilization of human milk oligosaccharides (HMOs), as several human-adapted species have dedicated genomic loci for transport and metabolism of these glycans. This results in the release of fermentation products into the gut lumen which may offer physiological benefits to the host. Synbiotic pairing of probiotic species with a cognate prebiotic delivers a competitive advantage, as the prebiotic provides a nutrient niche. METHODS: To determine the fitness advantage and metabolic characteristics of an HMO-catabolizing Bifidobacterium strain in the presence or absence of 2'-fucosyllactose (2'-FL), conventionally colonized mice were gavaged with either Bifidobacterium pseudocatenulatum MP80 (B.p. MP80) (as the probiotic) or saline during the first 3 days of the experiment and received water or water containing 2'-FL (as the prebiotic) throughout the study. RESULTS: 16S rRNA gene sequencing revealed that mice provided only B.p. MP80 were observed to have a similar microbiota composition as control mice throughout the experiment with a consistently low proportion of Bifidobacteriaceae present. Using 1H NMR spectroscopy, similar metabolic profiles of gut luminal contents and serum were observed between the control and B.p. MP80 group. Conversely, synbiotic supplemented mice exhibited dramatic shifts in their community structure across time with an overall increased, yet variable, proportion of Bifidobacteriaceae following oral inoculation. Parsing the synbiotic group into high and moderate bifidobacterial persistence based on the median proportion of Bifidobacteriaceae, significant differences in gut microbial diversity and metabolite profiles were observed. Notably, metabolites associated with the fermentation of 2'-FL by bifidobacteria were significantly greater in mice with a high proportion of Bifidobacteriaceae in the gut suggesting metabolite production scales with population density. Moreover, 1,2-propanediol, a fucose fermentation product, was only observed in the liver and brain of mice harboring high proportions of Bifidobacteriaceae. CONCLUSIONS: This study reinforces that the colonization of the gut with a commensal microorganism does not guarantee a specific functional output. Video Abstract.

Protocol to assess arteriovenous differences across the liver and hindlimb muscles in mice following treadmill exercise.

The tissue-specific release and uptake of metabolites in response to exercise is incompletely understood. Here, we detail a protocol to assess arteriovenous differences across the liver and hindlimb muscles in response to treadmill exercise in mice. We describe steps for the treadmill running of mice and the region-specific sampling of blood from the liver and hindlimb. This procedure is particularly relevant for the study of tissue-specific metabolism in response to exercise. For complete details on the use and execution of this protocol, please refer to Sato et al. (2022).1.

Seasonal light hours modulate peripheral clocks and energy metabolism in mice.

Except for latitudes close to the equator, seasonal variation in light hours can change dramatically between summer and winter. Yet investigations into the interplay between energy metabolism and circadian rhythms typically use a 12 h light:12 h dark photoperiod corresponding to the light duration at the equator. We hypothesized that altering the seasonal photoperiod affects both the rhythmicity of peripheral tissue clocks and energy homeostasis. Mice were housed at photoperiods representing either light hours in summer, winter, or the equinox. Mice housed at a winter photoperiod exhibited an increase in the amplitude of rhythmic lipid metabolism and a modest reduction in fat mass and liver triglyceride content. Comparing melatonin-proficient and -deficient mice, the effect of seasonal light on energy metabolism was largely driven by differences in the rhythmicity of food intake and not melatonin. Together, these data indicate that seasonal light impacts energy metabolism by modulating the timing of eating.

The 5-Cog paradigm to improve detection of cognitive impairment and dementia: clinical trial protocol.

Cognitive impairment related to dementia is under-diagnosed in primary care despite availability of numerous cognitive assessment tools; under-diagnosis is more prevalent for members of racial and ethnic minority groups. Clinical decision-support systems may improve rates of primary care providers responding to positive cognitive assessments with appropriate follow-up. The 5-Cog study is a randomized controlled trial in 1200 predominantly Black and Hispanic older adults from an urban underserved community who are presenting to primary care with cognitive concerns. The study will validate a novel 5-minute cognitive assessment coupled with an electronic medical record-embedded decision tree to overcome the barriers of current cognitive assessment paradigms in primary care and facilitate improved dementia care.

Dementia is common, though under-recognized, in older adults (OAs). Primary care providers (PCPs) miss opportunities to help patients and their families manage the disease because of failure to, or delay to, make an appropriate diagnosis. Black and Hispanic OAs are more likely than White OAs to experience delayed diagnosis. Most available memory tests are too long for practical use by PCPs, and are ill suited to patients of diverse language, cultural and educational backgrounds. Studies have shown that even when patients test positive for dementia in primary care, PCPs often do not take follow-up action. Our improved memory test, the 5-Cog, is brief (5 min), not biased by language issues (uses pictures and symbols instead of words), and simple (doesn't require expensive technology and complex staff training). The 5-Cog is paired with a clinical decision support tool, providing tailored recommendations directly into the patient's medical record, and making it easier for PCPs to take appropriate action. This study will evaluate whether the 5-Cog paradigm results in improved dementia care.

Comparative analysis of oral and intraperitoneal glucose tolerance tests in mice.

OBJECTIVE: The glucose tolerance test (GTT) is widely used in preclinical research to investigate glucose metabolism, but there is no standardised way to administer glucose. The aim of this study was to directly compare the effect of the route of glucose administration on glucose and insulin kinetics during a GTT in mice. METHODS: A GTT was performed in lean male and female mice and obese male mice and glucose was administered via the oral or intraperitoneal (I.P.) route. Samples were collected frequently during the GTT to provide a full time-course of the insulin and glucose excursions. In another cohort of lean male mice, plasma concentrations of insulin, c-peptide, and incretin hormones were measured at early time points after glucose administration. A stable-isotope labelled GTT (SiGTT) was then performed to delineate the contribution of exogenous and endogenous glucose to glycemia during the GTT, comparing both methods of glucose administration. Finally, we present a method to easily measure insulin from small volumes of blood during a GTT by directly assaying whole-blood insulin using ELISA and show a good concordance between whole-blood and plasma insulin measurements. RESULTS: We report that I.P. glucose administration results in an elevated blood glucose excursion and a largely absent elevation in blood insulin and plasma incretin hormones when compared to oral administration. Utilising stable-isotope labelled glucose, we demonstrate that the difference in glucose excursion between the two routes of administration is mainly due to the lack of suppression of glucose production in I.P. injected mice. Additionally, rates of exogenous glucose appearance into circulation were different between lean and obese mice after I.P., but not after oral glucose administration. CONCLUSION: Reflecting on these data, we suggest that careful consideration be given to the route of glucose administration when planning a GTT procedure in mice and that in most circumstances the oral route of glucose administration should be preferred over the I.P. route to avoid possible artifacts originating from a non-physiological route.

Lessons from Detecting Cognitive Impairment Including Dementia (DetectCID) in Primary Care.

BACKGROUND: Cognitive impairment, including dementia, is frequently under-detected in primary care. The Consortium for Detecting Cognitive Impairment, including Dementia (DetectCID) convenes three multidisciplinary teams that are testing novel paradigms to improve the frequency and quality of patient evaluations for detecting cognitive impairment in primary care and appropriate follow-up. OBJECTIVE: Our objective was to characterize the three paradigms, including similarities and differences, and to identify common key lessons from implementation. METHODS: A qualitative evaluation study with dementia specialists who were implementing the detection paradigms. Data was analyzed using content analysis. RESULTS: We identified core components of each paradigm. Key lessons emphasized the importance of engaging primary care teams, enabling primary care providers to diagnose cognitive disorders and provide ongoing care support, integrating with the electronic health record, and ensuring that paradigms address the needs of diverse populations. CONCLUSION: Approaches are needed that address the arc of care from identifying a concern to post-diagnostic management, are efficient and adaptable to primary care workflows, and address a diverse aging population. Our work highlights approaches to partnering with primary care that could be useful across specialties and paves the way for developing future paradigms that improve differential diagnosis of symptomatic cognitive impairment, identifying not only its presence but also its specific syndrome or etiology.

Atlas of exercise metabolism reveals time-dependent signatures of metabolic homeostasis.

Tissue sensitivity and response to exercise vary according to the time of day and alignment of circadian clocks, but the optimal exercise time to elicit a desired metabolic outcome is not fully defined. To understand how tissues independently and collectively respond to timed exercise, we applied a systems biology approach. We mapped and compared global metabolite responses of seven different mouse tissues and serum after an acute exercise bout performed at different times of the day. Comparative analyses of intra- and inter-tissue metabolite dynamics, including temporal profiling and blood sampling across liver and hindlimb muscles, uncovered an unbiased view of local and systemic metabolic responses to exercise unique to time of day. This comprehensive atlas of exercise metabolism provides clarity and physiological context regarding the production and distribution of canonical and novel time-dependent exerkine metabolites, such as 2-hydroxybutyrate (2-HB), and reveals insight into the health-promoting benefits of exercise on metabolism.

VDAC2 is required for truncated BID-induced mitochondrial apoptosis by recruiting BAK to the mitochondria.

Truncated BID (tBID), a proapoptotic BCL2 family protein, induces BAK/BAX-dependent release of cytochrome c and other mitochondrial intermembrane proteins to the cytosol to induce apoptosis. The voltage-dependent anion channels (VDACs) are the primary gates for solutes across the outer mitochondrial membrane (OMM); however, their role in apoptotic OMM permeabilization remains controversial. Here, we report that VDAC2(-/-) (V2(-/-)) mouse embryonic fibroblasts (MEFs) are virtually insensitive to tBID-induced OMM permeabilization and apoptosis, whereas VDAC1(-/-), VDAC3(-/-) and VDAC1(-/-)/VDAC3(-/-) MEFs respond normally to tBID. V2(-/-) MEFs regain tBID sensitivity after VDAC2 expression. Furthermore, V2(-/-) MEFs are deficient in mitochondrial BAK despite normal tBID-mitochondrial binding and BAX/BAK expression. tBID sensitivity of BAK(-/-) MEFs is also reduced, although not to the same extent as V2(-/-) MEFs, which might result from their strong overexpression of BAX. Indeed, addition of recombinant BAX also sensitized V2(-/-) MEFs to tBID. Thus, VDAC2 acts as a crucial component in mitochondrial apoptosis by allowing the mitochondrial recruitment of BAK, thereby controlling tBID-induced OMM permeabilization and cell death.

Building psychosocial programming in geriatrics fellowships: a consortium model.

Geriatric psychosocial problems are prevalent and significantly affect the physical health and overall well-being of older adults. Geriatrics fellows require psychosocial education, and yet to date, geriatrics fellowship programs have not developed a comprehensive geriatric psychosocial curriculum. Fellowship programs in the New York tristate area collaboratively created the New York Metropolitan Area Consortium to Strengthen Psychosocial Programming in Geriatrics Fellowships in 2007 to address this shortfall. The goal of the Consortium is to develop model educational programs for geriatrics fellows that highlight psychosocial issues affecting elder care, share interinstitutional resources, and energize fellowship program directors and faculty. In 2008, 2009, and 2010, Consortium faculty collaboratively designed and implemented a psychosocial educational conference for geriatrics fellows. Cumulative participation at the conferences included 146 geriatrics fellows from 20 academic institutions taught by interdisciplinary Consortium faculty. Formal evaluations from the participants indicated that the conference: a) positively affected fellows' knowledge of, interest in, and comfort with psychosocial issues; b) would have a positive impact on the quality of care provided to older patients; and c) encouraged valuable interactions with fellows and faculty from other institutions. The Consortium, as an educational model for psychosocial learning, has a positive impact on geriatrics fellowship training and may be replicable in other localities.

Bifidobacterium catabolism of human milk oligosaccharides overrides endogenous competitive exclusion driving colonization and protection.

Understanding how exogenous microbes stably colonize the animal gut is essential to reveal mechanisms of action and tailor effective probiotic treatments. Bifidobacterium species are naturally enriched in the gastrointestinal tract of breast-fed infants. Human milk oligosaccharides (HMOs) are associated with this enrichment. However, direct mechanistic proof of the importance of HMOs in this colonization is lacking given milk contains additional factors that impact the gut microbiota. This study examined mice supplemented with the HMO 2'fucosyllactose (2'FL) together with a 2'FL-consuming strain, Bifidobacterium pseudocatenulatum MP80. 2'FL supplementation creates a niche for high levels of B.p. MP80 persistence, similar to Bifidobacterium levels seen in breast-fed infants. This synergism impacted gut microbiota composition, activated anti-inflammatory pathways and protected against chemically-induced colitis. These results demonstrate that bacterial-milk glycan interactions alone drive enrichment of beneficial Bifidobacterium and provide a model for tunable colonization thus facilitating insight into mechanisms of health promotion by bifidobacteriain neonates.

Nampt controls skeletal muscle development by maintaining Ca2+ homeostasis and mitochondrial integrity.

OBJECTIVE: NAD+ is a co-factor and substrate for enzymes maintaining energy homeostasis. Nicotinamide phosphoribosyltransferase (NAMPT) controls NAD+ synthesis, and in skeletal muscle, NAD+ is essential for muscle integrity. However, the underlying molecular mechanisms by which NAD+ synthesis affects muscle health remain poorly understood. Thus, the objective of the current study was to delineate the role of NAMPT-mediated NAD+ biosynthesis in skeletal muscle development and function. METHODS: To determine the role of Nampt in muscle development and function, we generated skeletal muscle-specific Nampt KO (SMNKO) mice. We performed a comprehensive phenotypic characterization of the SMNKO mice, including metabolic measurements, histological examinations, and RNA sequencing analyses of skeletal muscle from SMNKO mice and WT littermates. RESULTS: SMNKO mice were smaller, with phenotypic changes in skeletal muscle, including reduced fiber area and increased number of centralized nuclei. The majority of SMNKO mice died prematurely. Transcriptomic analysis identified that the gene encoding the mitochondrial permeability transition pore (mPTP) regulator Cyclophilin D (Ppif) was upregulated in skeletal muscle of SMNKO mice from 2 weeks of age, with associated increased sensitivity of mitochondria to the Ca2+-stimulated mPTP opening. Treatment of SMNKO mice with the Cyclophilin D inhibitor, Cyclosporine A, increased membrane integrity, decreased the number of centralized nuclei, and increased survival. CONCLUSIONS: Our study demonstrates that NAMPT is crucial for maintaining cellular Ca2+ homeostasis and skeletal muscle development, which is vital for juvenile survival.