Spinal cord injury-induced neurogenic bowel: A role for host-microbiome interactions in bowel pain and dysfunction.

Background and aims: Spinal cord injury (SCI) affects roughly 300,000 Americans with 17,000 new cases added annually. In addition to paralysis, 60% of people with SCI develop neurogenic bowel (NB), a syndrome characterized by slow colonic transit, constipation, and chronic abdominal pain. The knowledge gap surrounding NB mechanisms after SCI means that interventions are primarily symptom-focused and largely ineffective. The goal of the present studies was to identify mechanism(s) that initiate and maintain NB after SCI as a critical first step in the development of evidence-based, novel therapeutic treatment options. Methods: Following spinal contusion injury at T9, we observed alterations in bowel structure and function reflecting key clinical features of NB. We then leveraged tissue-specific whole transcriptome analyses (RNAseq) and fecal 16S rRNA amplicon sequencing in combination with histological, molecular, and functional (Ca2+ imaging) approaches to identify potential mechanism(s) underlying the generation of the NB phenotype. Results: In agreement with prior reports focused on SCI-induced changes in the skin, we observed a rapid and persistent increase in expression of calcitonin gene-related peptide (CGRP) expression in the colon. This is suggestive of a neurogenic inflammation-like process engaged by antidromic activity of below-level primary afferents following SCI. CGRP has been shown to disrupt colon homeostasis and negatively affect peristalsis and colon function. As predicted, contusion SCI resulted in increased colonic transit time, expansion of lymphatic nodules, colonic structural and genomic damage, and disruption of the inner, sterile intestinal mucus layer corresponding to increased CGRP expression in the colon. Gut microbiome colonization significantly shifted over 28 days leading to the increase in Anaeroplasma, a pathogenic, gram-negative microbe. Moreover, colon specific vagal afferents and enteric neurons were hyperresponsive after SCI to different agonists including fecal supernatants. Conclusions: Our data suggest that SCI results in overexpression of colonic CGRP which could alter colon structure and function. Neurogenic inflammatory-like processes and gut microbiome dysbiosis can also sensitize vagal afferents, providing a mechanism for visceral pain despite the loss of normal sensation post-SCI. These data may shed light on novel therapeutic interventions targeting this process to prevent NB development in patients.

Human Milk Components and the Infant Gut Microbiome at 6 Months: Understanding the Interconnected Relationship.

BACKGROUND: Human milk oligosaccharides have been shown to relate to the infant gut microbiome. However, the impact of other human milk components on infant gut bacterial colonization remains unexplored. OBJECTIVES: Our cross-sectional analysis aimed to investigate associations between human milk components (energy, macronutrients, free amino acids, inflammatory markers, and hormones) and infant gut microbiome diversity and composition (phylum, family, and genus) at 6 mo of age. METHODS: Human milk and infant stool samples were collected at 6 mo postpartum. The infant gut microbiome was profiled using 16S rRNA sequencing. Linear regression models were performed to examine associations, adjusting for pregravid BMI (kg/m2), delivery mode, duration of human milk feeding, and infant sex, with q < 0.2 considered significant. RESULTS: This analysis included a total of 54 mothers (100% exclusively feeding human milk) and infants (n = 28 male; 51.9%). Total energy in human milk showed a negative association with α-diversity measures (Chao1 and Shannon). Interleukin (IL)-8 in human milk was positively associated with Chao1 and observed operational taxonomic units. At the family level, human milk glutamine and serine levels showed a negative association with the abundance of Veillonellaceae, whereas isoleucine showed a positive association with Bacteroidaceae. Human milk IL-8 and IL-6 concentrations were positively associated with Bacteroidaceae abundance. IL-8 also had a positive relationship with Bifidobacteriaceae, whereas it had a negative relationship with Streptococcacea and Clostridiaceae. Human milk IL-8 was positively associated with the phylum Bacteroidetes, and negatively associated with Proteobacteria. At the genus level, human milk IL-8 exhibited a positive relationship with Bacteroides, whereas human milk isoleucine had a negative relationship with Bacteroides and Ruminococcus. Pregravid BMI and sex effects were observed. CONCLUSIONS: IL-8 in human milk could potentially prepare the infant's immune system to respond effectively to various microorganisms, potentially promoting the growth of beneficial gut bacteria and protecting against pathogens.

VCD-induced menopause mouse model reveals reprogramming of hepatic metabolism.

OBJECTIVE: Menopause adversely impacts systemic energy metabolism and increases the risk of metabolic disease(s) including hepatic steatosis, but the mechanisms are largely unknown. Dosing female mice with vinyl cyclohexene dioxide (VCD) selectively causes follicular atresia in ovaries, leading to a murine menopause-like phenotype. METHODS: In this study, we treated female C57BL6/J mice with VCD (160 mg/kg i.p. for 20 consecutive days followed by verification of the lack of estrous cycling) to investigate changes in body composition, energy expenditure (EE), hepatic mitochondrial function, and hepatic steatosis across different dietary conditions. RESULTS: VCD treatment induced ovarian follicular loss and increased follicle-stimulating hormone (FSH) levels in female mice, mimicking a menopause-like phenotype. VCD treatment did not affect body composition, or EE in mice on a low-fat diet (LFD) or in response to a short-term (1-week) high-fat, high sucrose diet (HFHS). However, the transition to a HFHS lowered cage activity in VCD mice. A chronic HFHS diet (16 weeks) significantly increased weight gain, fat mass, and hepatic steatosis in VCD-treated mice compared to HFHS-fed controls. In the liver, VCD mice showed suppressed hepatic mitochondrial respiration on LFD, while chronic HFHS resulted in compensatory increases in hepatic mitochondrial respiration. Also, liver RNA sequencing revealed that VCD promoted global upregulation of hepatic lipid/cholesterol synthesis pathways. CONCLUSION: Our findings suggest that the VCD-induced menopause model compromises hepatic mitochondrial function and lipid/cholesterol homeostasis that sets the stage for HFHS diet-induced steatosis while also increasing susceptibility to obesity.

Effects of Follicle Stimulating Hormone on Energy Balance and Tissue Metabolic Health After Loss of Ovarian Function.

Loss of ovarian function imparts increased susceptibility to obesity and metabolic disease. These effects are largely attributed to decreased estradiol (E2), but the role of increased follicle stimulating hormone (FSH) in modulating energy balance has not been fully investigated. Previous work that blocked FSH binding to its receptor in mice suggested this hormone may play a part in modulating body weight and energy expenditure after ovariectomy. We used an alternate approach to isolate the individual and combined contributions of FSH and E2 in mediating energy imbalance and changes in tissue-level metabolic health. Female Wistar rats were ovariectomized and given the GnRH antagonist degarelix to suppress FSH production. E2 and FSH were then added back individually and in combination for a period of 3 weeks. Energy balance, body mass composition, and transcriptomic profiles of individual tissues were obtained. In contrast to previous studies, suppression and replacement of FSH in our paradigm had no effect on body weight, body composition, food intake, or energy expenditure. We did, however, observe organ-specific effects of FSH that produced unique transcriptomic signatures of FSH in retroperitoneal white adipose tissue. These included reductions in biological processes related to lipogenesis and carbohydrate transport. Additionally, rats administered FSH had reduced liver triglyceride concentration (p<0.001), which correlated with FSH-induced changes at the transcriptomic level. While not appearing to modulate energy balance after loss of ovarian function in rats, FSH may still impart tissue-specific effects in the liver and white adipose tissue that might affect the metabolic health of those organs.

Associations of infant feeding practices with abdominal and hepatic fat measures in childhood in the longitudinal Healthy Start Study.

BACKGROUND: Infant feeding patterns have been linked with obesity risk in childhood, but associations with precise measures of body fat distribution are unclear. OBJECTIVE: We examined associations of infant feeding practices with abdominal fat and hepatic fat trajectories in childhood. METHODS: This study included 356 children in the Healthy Start Study, a prospective prebirth cohort in Colorado. Infant feeding practices were assessed by postnatal interviews and categorized as any human milk <6 mo compared with ≥6 mo; complementary foods introduced ≤4 mo compared with >4 mo; soda introduced ≤18 mo compared with >18 mo. Abdominal subcutaneous (SAT) and visceral adipose tissue (VAT) areas and hepatic fat (%) were assessed by magnetic resonance imaging in early and middle childhood (median 5 and 9 y old, respectively). We examined associations of infant feeding with adiposity trajectories across childhood using linear mixed models. RESULTS: In the sample of children, 67% consumed human milk ≥6 mo, 75% were introduced to complementary foods at >4 mo, and 81% were introduced to soda at >18 mo. We did not find any associations between duration of any human milk consumption and childhood adiposity trajectories. Early introduction to complementary foods (≤4 mo) was associated with faster rates of change for SAT and VAT during childhood (Slope [95% CI]: 15.1 [10.7,19.4] cm2/y for SAT; 2.5 [1.9,2.9] cm2/y for VAT), compared with introduction at >4 mo (5.5 [3.0,8.0] cm2/y and 1.6 [1.3,1.9] cm2/y, respectively). Similarly, early introduction to soda (≤18 mo) was associated with faster rates of change for all 3 outcomes during childhood (Slope [95% CI]: 20.6 [15.0,26.1] cm2/y for SAT, 2.7 [2.0,3.3] cm2/y for VAT, 0.3 [0.1,0.5] %/year for hepatic fat) compared with delayed introduction (5.4 [2.8,8.0] cm2/y, 1.7 [1.3, 2.0] cm2/y, -0.1 [-0.2,0.0] %/y, respectively). CONCLUSIONS: The timing of introduction and quality of complementary foods in infancy was associated with rates of abdominal and hepatic fat accrual during childhood. Experimental studies are needed to assess underlying mechanisms.

Metabolic and fecal microbial changes in adult fetal growth restricted mice.

BACKGROUND: Fetal growth restriction (FGR) increases risk for development of obesity and type 2 diabetes. Using a mouse model of FGR, we tested whether metabolic outcomes were exacerbated by high-fat diet challenge or associated with fecal microbial taxa. METHODS: FGR was induced by maternal calorie restriction from gestation day 9 to 19. Control and FGR offspring were weaned to control (CON) or 45% fat diet (HFD). At age 16 weeks, offspring underwent intraperitoneal glucose tolerance testing, quantitative MRI body composition assessment, and energy balance studies. Total microbial DNA was used for amplification of the V4 variable region of the 16 S rRNA gene. Multivariable associations between groups and genera abundance were assessed using MaAsLin2. RESULTS: Adult male FGR mice fed HFD gained weight faster and had impaired glucose tolerance compared to control HFD males, without differences among females. Irrespective of weaning diet, adult FGR males had depletion of Akkermansia, a mucin-residing genus known to be associated with weight gain and glucose handling. FGR females had diminished Bifidobacterium. Metabolic changes in FGR offspring were associated with persistent gut microbial changes. CONCLUSION: FGR results in persistent gut microbial dysbiosis that may be a therapeutic target to improve metabolic outcomes. IMPACT: Fetal growth restriction increases risk for metabolic syndrome later in life, especially if followed by rapid postnatal weight gain. We report that a high fat diet impacts weight and glucose handling in a mouse model of fetal growth restriction in a sexually dimorphic manner. Adult growth-restricted offspring had persistent changes in fecal microbial taxa known to be associated with weight, glucose homeostasis, and bile acid metabolism, particularly Akkermansia, Bilophilia and Bifidobacteria. The gut microbiome may represent a therapeutic target to improve long-term metabolic outcomes related to fetal growth restriction.

Maternal Exercise Prior to and during Gestation Induces Sex-Specific Alterations in the Mouse Placenta.

While exercise (EX) during pregnancy is beneficial for both mother and child, little is known about the mechanisms by which maternal exercise mediates changes in utero. Six-week-old female C57BL/6 mice were divided into two groups: with (exercise, EX; N = 7) or without (sedentary, SED; N = 8) access to voluntary running wheels. EX was provided via 24 h access to wheels for 10 weeks prior to conception until late pregnancy (18.5 days post coitum). Sex-stratified placentas and fetal livers were collected. Microarray analysis of SED and EX placentas revealed that EX affected gene transcript expression of 283 and 661 transcripts in male and female placentas, respectively (±1.4-fold, p < 0.05). Gene Set Enrichment and Ingenuity Pathway Analyses of male placentas showed that EX led to inhibition of signaling pathways, biological functions, and down-regulation of transcripts related to lipid and steroid metabolism, while EX in female placentas led to activation of pathways, biological functions, and gene expression related to muscle growth, brain, vascular development, and growth factors. Overall, our results suggest that the effects of maternal EX on the placenta and presumably on the offspring are sexually dimorphic.

Sex Differences in the Skeletal Muscle Response to a High Fat, High Sucrose Diet in Rats.

Men are diagnosed with type 2 diabetes at lower body mass indexes than women; the role of skeletal muscle in this sex difference is poorly understood. Type 2 diabetes impacts skeletal muscle, particularly in females who demonstrate a lower oxidative capacity compared to males. To address mechanistic differences underlying this sex disparity, we investigated skeletal muscle mitochondrial respiration in female and male rats in response to chronic high-fat, high-sugar (HFHS) diet consumption. Four-week-old Wistar Rats were fed a standard chow or HFHS diet for 14 weeks to identify sex-specific adaptations in mitochondrial respirometry and characteristics, transcriptional patterns, and protein profiles. Fat mass was greater with the HFHS diet in both sexes when controlled for body mass (p < 0.0001). Blood glucose and insulin resistance were greater in males (p = 0.01) and HFHS-fed rats (p < 0.001). HFHS-fed males had higher mitochondrial respiration compared with females (p < 0.01 sex/diet interaction). No evidence of a difference by sex or diet was found for mitochondrial synthesis, dynamics, or quality to support the mitochondrial respiration sex/diet interaction. However, transcriptomic analyses indicate sex differences in nutrient handling. Sex-specific differences occurred in PI3K/AKT signaling, PPARα/RXRα, and triacylglycerol degradation. These findings may provide insight into the clinical sex differences in body mass index threshold for diabetes development and tissue-specific progression of insulin resistance.

Associations between ambient temperature and pregnancy outcomes from three south Asian sites of the Global Network Maternal Newborn Health Registry: A retrospective cohort study.

OBJECTIVE: Growing evidence suggests that environmental heat stress negatively influences fetal growth and pregnancy outcomes. However, few studies have examined the impact of heat stress on pregnancy outcomes in low-resource settings. We combined data from a large multi-country maternal-child health registry and meteorological data to assess the impacts of heat stress. DESIGN: Retrospective cohort study. SETTING: Three sites based in south Asia as part of the Global Network for Women's and Children's Health research in India (Belagavi and Nagpur) and Pakistan (Thatta). POPULATION OR SAMPLE: Data from women enrolled between 2014 and 2020 in the Global Network's Maternal Newborn Health Registry (MNHR), a prospective, population-based registry of pregnancies, were used. METHODS: A total of 126 273 pregnant women were included in this analysis. Daily maximal air temperatures (Tmax ) were acquired from local meteorological records. Associations between averages of daily maximal temperatures for each trimester and main outcomes were analysed using a modified Poisson regression approach. MAIN OUTCOMES MEASURES: Incidence of stillbirth, preterm birth, low birthweight (<2500 g) or evidence of pregnancy hypertension or pre-eclampsia. RESULTS: In the overall cohort, risk of preterm birth was positively associated with greater temperature in the second trimester (relative risk [RR] 1.05, 95% CI 1.02-1.07, p = 0.0002). Among individual sites, the risk of preterm birth was greatest in Nagpur (RR 1.07, 95% CI 1.03-1.11, p = 0.0005) and associated with second-trimester temperature. The overall risk of low birthweight was associated with ambient temperature in second trimester (RR 1.02, 95% CI 1.01-1.04, p = 0.01). The risk for LBW was associated with first-trimester heat in Thatta and with second-trimester heat in Nagpur. Finally, the overall risk of gestational hypertensive disease was associated with greater temperature in the third trimester among all sites (RR 1.07, 95% CI 1.02-1.12, p = 0.005) and was particularly significant for Nagpur (RR 1.13, 95% CI 1.05-1.23, p = 0.002). These findings highlight the increased risk of detrimental obstetric and neonatal outcomes with greater temperature. CONCLUSION: In a multi-country, community-based study, greater risk of adverse outcomes was observed with increasing temperature. The study highlights the need for deeper understanding of covarying factors and intervention strategies, especially in regions where high temperatures are common.

Microbial taxonomic and functional shifts in adolescents with type 1 diabetes are associated with clinical and dietary factors.

BACKGROUND: Evidence indicates a link between the pathogenesis of type 1 diabetes (T1D) and the gut microbiome. However, the regulation of microbial metabolic pathways and the associations of bacterial species with dietary factors in T1D are largely unknown. We investigated whether microbial metagenomic signatures in adolescents with T1D are associated with clinical/dietary factors. METHODS: Adolescents with T1D (case) and healthy adolescents (control) were recruited, and microbiome profiling in participants' stool samples was performed using shotgun metagenomic sequencing. The bioBakery3 pipeline (Kneaddata, Metaphlan 4 and HUMAnN) was used to assign taxonomy and functional annotations. Clinical (HbA1c) and dietary information (3-day food record) were collected for conducting association analysis using Spearman's correlation. FINDINGS: Adolescents with T1D exhibited modest changes in taxonomic composition of gut microbiome. Nineteen microbial metabolic pathways were altered in T1D, including downregulation of biosynthesis of vitamins (B2/flavin, B7/biotin and B9/folate), enzyme cofactors (NAD+ and s-adenosyl methionine) and amino acids (aspartate, asparagine and lysine) with an upregulation in the fermentation pathways. Furthermore, bacterial species associated with dietary and clinical factors differed between healthy adolescents and adolescents with T1D. Supervised models modeling identified taxa predictive of T1D status, and the top features included Coprococcus and Streptococcus. INTERPRETATION: Our study provides new insight into the alteration of microbial and metabolic signatures in adolescents with T1D, suggesting that microbial biosynthesis of vitamins, enzyme cofactors and amino acids may be potentially altered in T1D. FUNDING: Research grants from NIH/NCCIH: R01AT010247 and USDA/NIFA: 2019-67017-29253; and Larry & Gail Miller Family Foundation Assistantship.

Pre- and Post-Sexual Maturity Liver-specific ERα Knockout Does Not Impact Hepatic Mitochondrial Function.

Compared with males, premenopausal women and female rodents are protected against hepatic steatosis and present with higher functioning mitochondria (greater hepatic mitochondrial respiration and reduced H2O2 emission). Despite evidence that estrogen action mediates female protection against steatosis, mechanisms remain unknown. Here we validated a mouse model with inducible reduction of liver estrogen receptor alpha (ERα) (LERKO) via adeno-associated virus (AAV) Cre. We phenotyped the liver health and mitochondrial function of LERKO mice (n = 10-12 per group) on a short-term high-fat diet (HFD), and then tested whether timing of LERKO induction at 2 timepoints (sexually immature: 4 weeks old [n = 11 per group] vs sexually mature: 8-10 weeks old [n = 8 per group]) would impact HFD-induced outcomes. We opted for an inducible LERKO model due to known estrogen-mediated developmental programming, and we reported both receptor and tissue specificity with our model. Control mice were ERαfl/fl receiving AAV with green fluorescent protein (GFP) only. Results show that there were no differences in body weight/composition or hepatic steatosis in LERKO mice with either short-term (4-week) or chronic (8-week) high-fat feeding. Similarly, LERKO genotype nor timing of LERKO induction (pre vs post sexual maturity) did not alter hepatic mitochondrial O2 and H2O2 flux, coupling, or OXPHOS protein. Transcriptomic analysis showed that hepatic gene expression in LERKO was significantly influenced by developmental stage. Together, these studies suggest that hepatic ERα is not required in female protection against HFD-induced hepatic steatosis nor does it mediate sexual dimorphism in liver mitochondria function.

Association of Maternal BMI and Rapid Infant Weight Gain With Childhood Body Size and Composition.

OBJECTIVES: Maternal prepregnancy BMI (ppBMI) and an infant's rapid weight gain (RWG) are each associated with increased risk for childhood obesity. We hypothesized that ppBMI and RWG interact to further raise childhood obesity risk. METHODS: Mother-infant dyads (n = 414) from the Healthy Start Study, an observational prebirth cohort, were included. RWG was defined as a weight-for-age z score increase of ≥0.67 from birth to 3 to 7 months. Body composition was measured by air displacement plethysmography at age 4 to 7 years. General linear regression models were fit to characterize associations between ppBMI, RWG, and their interaction with the outcomes of childhood BMI-for-age z score and percent fat mass (%FM). RESULTS: A total of 18.6% (n = 77) of offspring experienced RWG. Maternal ppBMI and RWG were both positively associated with offspring BMI z score and %FM. RWG amplified the association between ppBMI and BMI z score, especially among females. Females exposed to maternal obesity and RWG had an average BMI at the 94th percentile (1.50 increase in childhood BMI z score) compared with those exposed to normal ppBMI and no RWG (average childhood BMI at the 51st percentile). RWG had a weaker effect on the association between ppBMI and %FM. Adjustment for breastfeeding status or childhood daily caloric intake did not significantly alter findings. CONCLUSIONS: Rapid infant weight gain interacts with maternal ppBMI to jointly exacerbate risk of childhood obesity. Pediatric providers should monitor infants for RWG, especially in the context of maternal obesity, to reduce future risk of obesity.

Beta-adrenergic agonist induces unique transcriptomic signature in inguinal white adipose tissue.

Activation of thermogenic adipose tissue depots has been linked to improved metabolism and weight loss. To study the molecular regulation of adipocyte thermogenesis, we performed RNA-Seq on brown adipose tissue (BAT), gonadal white adipose tissue (gWAT), and inguinal white adipose tissue (iWAT) from mice treated with ß3-adrenoreceptor agonist CL316,243 (CL). Our analysis revealed diverse transcriptional profile and identified pathways in response to CL treatment. Differentially expressed genes (DEGs) in iWATCL were associated with the upregulation of pathways involved in cellular immune responses and with the upregulation of the browning program. We identified 39 DEGs in beige adipose which included certain heat shock proteins (Hspa1a and Hspa1b), and others suggesting potential associations with browning. Our results highlight transcriptional heterogeneity across adipose tissues and reveal genes specifically regulated in beige adipose, potentially aiding in identifying novel browning pathways.

Maternal Diet Quality During Pregnancy and Offspring Hepatic Fat in Early Childhood: The Healthy Start Study.

BACKGROUND: Overnutrition in utero may increase offspring risk of nonalcoholic fatty liver disease (NAFLD), but the specific contribution of maternal diet quality during pregnancy to this association remains understudied in humans. OBJECTIVES: This study aimed to examine the associations of maternal diet quality during pregnancy with offspring hepatic fat in early childhood (median: 5 y old, range: 4-8 y old). METHODS: Data were from 278 mother-child pairs in the longitudinal, Colorado-based Healthy Start Study. Multiple 24-h recalls were collected from mothers during pregnancy on a monthly basis (median: 3 recalls, range: 1-8 recalls starting after enrollment), and used to estimate maternal usual nutrient intakes and dietary pattern scores [Healthy Eating Index-2010 (HEI-2010), Dietary Inflammatory Index (DII), and Relative Mediterranean Diet Score (rMED)]. Offspring hepatic fat was measured in early childhood by MRI. Associations of maternal dietary predictors during pregnancy with offspring log-transformed hepatic fat were assessed using linear regression models adjusted for offspring demographics, maternal/perinatal confounders, and maternal total energy intake. RESULTS: Higher maternal fiber intake and rMED scores during pregnancy were associated with lower offspring hepatic fat in early childhood in fully adjusted models [Back-transformed ß (95% CI): 0.82 (0.72, 0.94) per 5 g/1000 kcal fiber; 0.93 (0.88, 0.99) per 1 SD for rMED]. In contrast, higher maternal total sugar and added sugar intakes, and DII scores were associated with higher offspring hepatic fat [Back-transformed ß (95% CI): 1.18 (1.05, 1.32) per 5% kcal/d added sugar; 1.08 (0.99, 1.18) per 1 SD for DII]. Analyses of dietary pattern subcomponents also revealed that lower maternal intakes of green vegetables and legumes and higher intake of "empty calories" were associated with higher offspring hepatic fat in early childhood. CONCLUSIONS: Poorer maternal diet quality during pregnancy was associated with greater offspring susceptibility to hepatic fat in early childhood. Our findings provide insights into potential perinatal targets for the primordial prevention of pediatric NAFLD.

Maternal nutritional status modifies heat-associated growth restriction in women with chronic malnutrition.

Rapid changes in the global climate are deepening existing health disparities from resource scarcity and malnutrition. Rising ambient temperatures represent an imminent risk to pregnant women and infants. Both maternal malnutrition and heat stress during pregnancy contribute to poor fetal growth, the leading cause of diminished child development in low-resource settings. However, studies explicitly examining interactions between these two important environmental factors are lacking. We leveraged maternal and neonatal anthropometry data from a randomized controlled trial focused on improving preconception maternal nutrition (Women First Preconception Nutrition trial) conducted in Thatta, Pakistan, where both nutritional deficits and heat stress are prevalent. Multiple linear regression of ambient temperature and neonatal anthropometry at birth (n = 459) showed a negative association between daily maximal temperatures in the first trimester and Z-scores of birth length and head circumference. Placental mRNA-sequencing and protein analysis showed transcriptomic changes in protein translation, ribosomal proteins, and mTORC1 signaling components in term placenta exposed to excessive heat in the first trimester. Targeted metabolomic analysis indicated ambient temperature associated alterations in maternal circulation with decreases in choline concentrations. Notably, negative impacts of heat on birth length were in part mitigated in women randomized to comprehensive maternal nutritional supplementation before pregnancy suggesting potential interactions between heat stress and nutritional status of the mother. Collectively, the findings bridge critical gaps in our current understanding of how maternal nutrition may provide resilience against adverse effects of heat stress in pregnancy.

VCD-induced menopause mouse model reveals reprogramming of hepatic metabolism.

Menopause adversely impacts systemic energy metabolism and increases the risk of metabolic disease(s) including hepatic steatosis, but the mechanisms are largely unknown. Dosing female mice with vinyl cyclohexene dioxide (VCD) selectively causes follicular atresia in ovaries, leading to a murine menopause-like phenotype. In this study, we treated female C57BL6/J mice with VCD (160mg/kg i.p. for 20 consecutive days followed by verification of the lack of estrous cycling) to investigate changes in body composition, energy expenditure (EE), hepatic mitochondrial function, and hepatic steatosis across different dietary conditions. VCD treatment induced ovarian follicular loss and increased follicle-stimulating hormone (FSH) levels in female mice, mimicking a menopause-like phenotype. VCD treatment did not affect body composition, or EE in mice on a low-fat diet or in response to a short-term (1-week) high-fat, high sucrose diet (HFHS). However, the transition to a HFHS lowered cage activity in VCD mice. A chronic HFHS diet (16 weeks) significantly increased weight gain, fat mass, and hepatic steatosis in VCD-treated mice compared to HFHS-fed controls. In the liver, VCD mice showed suppressed hepatic mitochondrial respiration on LFD, while chronic HFHS diet resulted in compensatory increases in hepatic mitochondrial respiration. Also, liver RNA sequencing revealed that VCD promoted global upregulation of hepatic lipid/cholesterol synthesis pathways. Our findings suggest that the VCD- induced menopause model compromises hepatic mitochondrial function and lipid/cholesterol homeostasis that sets the stage for HFHS diet-induced steatosis while also increasing susceptibility to obesity.

Oral combined contraceptives induce liver mitochondrial reactive oxygen species and whole-body metabolic adaptations in female mice.

Compared to age-matched men, pre-menopausal women show greater resilience against cardiovascular disease (CVD), hepatic steatosis, diabetes and obesity - findings that are widely attributed to oestrogen. However, meta-analysis data suggest that current use of oral combined contraceptives (OC) is a risk factor for myocardial infarction, and OC use further compounds with metabolic disease risk factors to increase CVD susceptibility. While mitochondrial function in tissues such as the liver and skeletal muscle is an emerging mechanism by which oestrogen may confer its protection, effects of OC use on mitochondria and metabolism in the context of disease risk remain unexplored. To answer this question, female C57Bl/6J mice were fed a high fat diet and treated with vehicle or OCs for 3, 12 or 20 weeks (n = 6 to 12 per group) at a dose and ratio that mimic the human condition of cycle cessation in the low oestrogen, high progesterone stage. Liver and skeletal muscle mitochondrial function (respiratory capacity, H2 O2 , coupling) was measured along with clinical outcomes of cardiometabolic disease such as obesity, glucose tolerance, hepatic steatosis and aortic atherosclerosis. The main findings indicate that regardless of treatment duration, OCs robustly increase hepatic mitochondrial H2 O2 levels, likely due to diminished antioxidant capacity, but have no impact on muscle mitochondrial H2 O2 . Furthermore, OC-treated mice had lower adiposity and hepatic triglyceride content compared to control mice despite reduced wheel running, spontaneous physical activity and total energy expenditure. Together, these studies describe tissue-specific effects of OC use on mitochondria as well as variable impacts on markers of metabolic disease susceptibility. KEY POINTS: Oestrogen loss in women increases risk for cardiometabolic diseases, a link that has been partially attributed to negative impacts on mitochondria and energy metabolism. To study the effect of oral combined contraceptives (OCs) on hepatic and skeletal muscle mitochondria and whole-body energy metabolism, we used an animal model of OCs which mimics the human condition of cessation of hormonal cycling in the low oestrogen, high progesterone state. OC-treated mice have increased hepatic mitochondrial oxidative stress and decreased physical activity and energy expenditure, despite displaying lower adiposity and liver fat at this time point. These pre-clinical data reveal tissue-specific effects of OCs that likely underlie the clinical findings of increased cardiometabolic disease in women who use OCs compared to non-users, when matched for obesity.

Gut Microbiome and Metabolome Modulation by Maternal High-Fat Diet and Thermogenic Challenge.

The gut microbiota plays a critical role in energy homeostasis and its dysbiosis is associated with obesity. Maternal high-fat diet (HFD) and ß-adrenergic stimuli alter the gut microbiota independently; however, their collective regulation is not clear. To investigate the combined effect of these factors on offspring microbiota, 20-week-old offspring from control diet (17% fat)- or HFD (45% fat)-fed dams received an injection of either vehicle or ß3-adrenergic agonist CL316,243 (CL) for 7 days and then cecal contents were collected for bacterial community profiling. In a follow-up study, a separate group of mice were exposed to either 8 °C or 30 °C temperature for 7 days and blood serum and cecal contents were used for metabolome profiling. Both maternal diet and CL modulated the gut bacterial community structure and predicted functional profiles. Particularly, maternal HFD and CL increased the Firmicutes/Bacteroidetes ratio. In mice exposed to different temperatures, the metabolome profiles clustered by treatment in both the cecum and serum. Identified metabolites were enriched in sphingolipid and amino acid metabolism in the cecum and in lipid and energy metabolism in the serum. In summary, maternal HFD altered offspring's response to CL and altered microbial composition and function. An independent experiment supported the effect of thermogenic challenge on the bacterial function through metabolome change.

Body composition trajectories from birth to 5 years and hepatic fat in early childhood.

BACKGROUND: Adiposity is an established risk factor for pediatric nonalcoholic fatty liver disease (NAFLD), but little is known about the influence of body composition patterns earlier in life on NAFLD risk. OBJECTIVES: We aimed to examine associations of body composition at birth and body composition trajectories from birth to early childhood with hepatic fat in early childhood. METHODS: Data were from the longitudinal Healthy Start Study in Colorado. Fat-free mass index (FFMI), fat mass index (FMI), percentage body fat (BF%), and BMI were assessed at birth and/or ∼5 y in >1200 children by air displacement plethysmography and anthropometrics. In a subset (n = 285), hepatic fat was also assessed at ∼5 y by MRI. We used a 2-stage modeling approach: first, we fit body composition trajectories from birth to early childhood using mixed models with participant-specific intercepts and linear slopes (i.e., individual deviations from the population average at birth and rate of change per year, respectively); second, associations of participant-specific trajectory deviations with hepatic fat were assessed by multivariable-adjusted linear regression. RESULTS: Participant-specific intercepts at birth for FFMI, FMI, BF%, and BMI were inversely associated with log-hepatic fat in early childhood in models adjusted for offspring demographics and maternal/prenatal variables [back-transformed ß (95% CI) per 1 SD: 0.93 (0.88, 0.99), 0.94 (0.88, 0.99), 0.94 (0.89, 0.99), and 0.90 (0.85, 0.96), respectively]. Whereas, faster velocities for BF% and BMI from birth to ∼5 y were positively associated with log-hepatic fat [back-transformed ß (95% CI) per 1 SD: 1.08 (1.01, 1.15) and 1.08 (1.02, 1.15), respectively]. These latter associations of BF% and BMI velocities with childhood hepatic fat were attenuated to the null when adjusted for participant-specific intercepts at birth. CONCLUSIONS: Our findings suggest that a smaller birth weight, combined with faster adiposity accretion in the first 5 y, predicts higher hepatic fat in early childhood. Strategies aiming to promote healthy body composition early in life may be critical for pediatric NAFLD prevention.This study was registered voluntarily at clinicaltrials.gov as NCT02273297.