High maternal adiposity during pregnancy programs an imbalance in the lipidome and predisposes to diet-induced hepatosteatosis in the offspring.

BACKGROUND: Exposure to high maternal adiposity in utero is a significant risk factor for the later-life development of metabolic syndrome (MetS), including non-alcoholic fatty liver disease (NAFLD). We have previously shown that high pre-pregnancy adiposity programs adipose tissue dysfunction in the offspring, leading to spillover of fatty acids into the circulation, a key pathogenic event in obesity-associated MetS. Herein, we hypothesized that programming of adipose tissue dysfunction in offspring born to overweight dams increases the risk for developing NAFLD. RESULTS: Females heterozygous for leptin receptor deficiency (Hetdb) were used as a model of high pre-pregnancy adiposity. Female wild-type (Wt) offspring born to Hetdb pregnancies gained significantly more body fat following high-fat/fructose diet (HFFD) compared with Wt offspring born to Wt dams. HFFD increased circulating free fatty acids (FFA) in male offspring of control dams, while FFA levels were similar in HFFD-fed offspring from Wt dams and CD or HFFD-fed Wt offspring from Hetdb dams. Despite female-specific protection from diet-induced FFA spillover, both male and female offspring from Hetdb dams were more susceptible to diet-induced hepatosteatosis. Lipidomic analysis revealed that CD-offspring of overweight dams had decreased hepatic polyunsaturated FA (PUFA) levels compared with control offspring. Changes to saturated FA (SFA) and the de novo lipogenic (DNL) index were diet driven; however, there was a significant effect of the intrauterine environment on FA elongation and Δ9 desaturase activity. CONCLUSION: High maternal adiposity during pregnancy programs a susceptibility to diet-induced hepatosteatosis.

An Integrated Multi-OMICS Approach Highlights Elevated Non-Esterified Fatty Acids Impact BeWo Trophoblast Metabolism and Lipid Processing.

Maternal obesity and gestational diabetes mellitus (GDM) are linked with impaired placental function and early onset of non-communicable cardiometabolic diseases in offspring. Previous studies have highlighted that the dietary non-esterified fatty acids (NEFAs) palmitate (PA) and oleate (OA), key dietary metabolites associated with maternal obesity and GDM, are potential modulators of placental lipid processing. Using the BeWo cell line model, the current study integrated transcriptomic (mRNA microarray), metabolomic, and lipidomic readouts to characterize the underlying impacts of exogenous PA and OA on placental villous trophoblast cell metabolism. Targeted gas chromatography and thin-layer chromatography highlighted that saturated and monounsaturated NEFAs differentially impact BeWo cell lipid profiles. Furthermore, cellular lipid profiles differed when exposed to single and multiple NEFA species. Additional multi-omic analyses suggested that PA exposure is associated with enrichment in ß-oxidation pathways, while OA exposure is associated with enrichment in anti-inflammatory and antioxidant pathways. Overall, this study further demonstrated that dietary PA and OA are important regulators of placental lipid metabolism. Encouraging appropriate dietary advice and implementing dietary interventions to maintain appropriate placental function by limiting excessive exposure to saturated NEFAs remain crucial in managing at-risk obese and GDM pregnancies.

Delta-6 desaturase (Fads2) deficiency alters triacylglycerol/fatty acid cycling in murine white adipose tissue.

The Δ-6 desaturase (D6D) enzyme is not only critical for the synthesis of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from α-linolenic acid (ALA), but recent evidence suggests that it also plays a role in adipocyte lipid metabolism and body weight; however, the mechanisms remain largely unexplored. The goal of this study was to investigate if a D6D deficiency would inhibit triacylglycerol storage and alter lipolytic and lipogenic pathways in mouse white adipose tissue (WAT) depots due to a disruption in EPA and DHA production. Male C57BL/6J D6D knockout (KO) and wild-type (WT) mice were fed either a 7% w/w lard or flax (ALA rich) diet for 21 weeks. Energy expenditure, physical activity, and substrate utilization were measured with metabolic caging. Inguinal and epididymal WAT depots were analyzed for changes in tissue weight, fatty acid composition, adipocyte size, and markers of lipogenesis, lipolysis, and insulin signaling. KO mice had lower body weight, higher serum nonesterified fatty acids, smaller WAT depots, and reduced adipocyte size compared to WT mice without altered food intake, energy expenditure, or physical activity, regardless of the diet. Markers of lipogenesis and lipolysis were more highly expressed in KO mice compared to WT mice in both depots, regardless of the diet. These changes were concomitant with lower basal insulin signaling in WAT. Collectively, a D6D deficiency alters triacylglycerol/fatty acid cycling in WAT by promoting lipolysis and reducing fatty acid re-esterification, which may be partially attributed to a reduction in WAT insulin signaling.

A reduction of skeletal muscle DHA content does not result in impaired whole body glucose tolerance or skeletal muscle basal insulin signaling in otherwise healthy mice.

Delta-6 desaturase (D6D), encoded by the Fads2 gene, catalyzes the first step in the conversion of α-linolenic acid to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The ablation of D6D in whole body Fads2-/- knockout (KO) mice results in an inability to endogenously produce EPA and DHA. Evidence supports a beneficial role for EPA and DHA on insulin-stimulated glucose disposal in skeletal muscle in the context of a metabolic challenge; however, it is unknown how low EPA and DHA levels impact skeletal muscle fatty acid composition and insulin signaling in a healthy context. The objective of this study was to examine the impact of ablating the endogenous production of EPA and DHA on skeletal muscle fatty acid composition, whole body glucose and insulin tolerance, and a key marker of skeletal muscle insulin signaling (pAkt). Male C57BL/6J wild-type (WT), Fads2+/- heterozygous, and Fads2-/- KO mice were fed a low-fat diet (16% kcal from fat) modified to contain either 7% w/w lard or 7% w/w flaxseed for 21 wk. No differences in total phospholipid (PL), triacylglycerol, or reactive lipid content were observed between genotypes. As expected, KO mice on both diets had significantly less DHA content in skeletal muscle PL. Despite this, KO mice did not have significantly different glucose or insulin tolerance compared with WT mice on either diet. Basal pAktSer473 was not significantly different between the genotypes within each diet. Ultimately, this study shows for the first time, to our knowledge, that the reduction of DHA in skeletal muscle is not necessarily detrimental to glucose homeostasis in otherwise healthy animals.NEW & NOTEWORTHY Skeletal muscle is the primary location of insulin-stimulated glucose uptake. EPA and DHA supplementation has been observed to improve skeletal muscle insulin-stimulated glucose uptake in models of metabolic dysfunction. Fads2-/- knockout mice cannot endogenously produce long-chain n-3 polyunsaturated fatty acids. Our results show that the absence of DHA in skeletal muscle is not detrimental to whole body glucose homeostasis in healthy mice.

Feasibility of MRI Quantification of Myelin Water Fraction in the Fetal Guinea Pig Brain.

BACKGROUND: Fetal myelination assessment is important for understanding neurodevelopment and neurodegeneration. Myelin water imaging (MWI) quantifies myelin water fraction (MWF), a validated marker for myelin content, and has been used to assess brain myelin in children and neonates. PURPOSE: To demonstrate that MWI can quantify MWF in fetal guinea pigs (GPs). STUDY TYPE: Animal model. ANIMAL MODEL: Nine pregnant, Dunkin-Hartley GPs with 31 fetuses (mean ± standard deviation = 60 ± 1.5 days gestation). FIELD STRENGTH/SEQUENCE: 3D spoiled gradient echo and balanced steady-state free precession sequences at 3.0 T. ASSESSMENT: MWF maps were reconstructed for maternal and fetal GP brains using the multicomponent driven equilibrium single pulse observation of T1 and T2 (mcDESPOT) approach. Myelin basic protein (MBP) stain provided histological validation of the MWF. Regions of interest were placed in the maternal corpus callosum (CC), maternal fornix (FOR), fetal CC, and fetal FOR in MWF maps and MBP stains. STATISTICAL TESTS: Linear regression between MWF and MBP stain intensity (SI) of all four regions (coefficient of determination, R2 ). A paired t-test compared the MWF of maternal and mean fetal CC, MBP SI of maternal and mean fetal CC, MWF of maternal and mean fetal FOR, MBP SI of maternal and mean fetal FOR. A paired t-test with a linear mixed model compared the MWF of fetal CC and fetal FOR, and MBP SI of fetal CC and fetal FOR. A  P value < 0.0083 was considered statistically significant. RESULTS: The mean MWF of the analyzed regions are as follows (mean ± standard deviation): 0.338 + 0.016 (maternal CC), 0.340 ± 0.017 (maternal FOR), 0.214 ± 0.016 (fetal CC), and 0.305 ± 0.025 (fetal FOR). MWF correlated with MBP SI in all regions (R2  = 0.81). Significant differences were found between MWF and MBP SI of maternal and fetal CC, and MWF and MBP SI of fetal CC and fetal FOR. DATA CONCLUSION: This study demonstrated the feasibility of MWI in assessing fetal brain myelin content. EVIDENCE LEVEL: 2 Technical Efficacy: Stage 1.

Maternal Fructose Intake Causes Developmental Reprogramming of Hepatic Mitochondrial Catalytic Activity and Lipid Metabolism in Weanling and Young Adult Offspring.

Excess dietary fructose is a major public health concern, yet little is known about its influence on offspring development and later-life disease when consumed in excess during pregnancy. To determine whether increased maternal fructose intake could have long-term consequences on offspring health, we investigated the effects of 10% w/v fructose water intake during preconception and pregnancy in guinea pigs. Female Dunkin Hartley guinea pigs were fed a control diet (CD) or fructose diet (FD; providing 16% of total daily caloric intake) ad libitum 60 days prior to mating and throughout gestation. Dietary interventions ceased at day of delivery. Offspring were culled at day 21 (D21) (weaning) and at 4 months (4 M) (young adult). Fetal exposure to excess maternal fructose intake significantly increased male and female triglycerides at D21 and 4 M and circulating palmitoleic acid and total omega-7 through day 0 (D0) to 4 M. Proteomic and functional analysis of significantly differentially expressed proteins revealed that FD offspring (D21 and 4 M) had significantly increased mitochondrial metabolic activities of ß-oxidation, electron transport chain (ETC) and oxidative phosphorylation and reactive oxygen species production compared to the CD offspring. Western blotting analysis of both FD offspring validated the increased protein abundances of mitochondrial ETC complex II and IV, SREBP-1c and FAS, whereas VDAC1 expression was higher at D21 but lower at 4 M. We provide evidence demonstrating offspring programmed hepatic mitochondrial metabolism and de novo lipogenesis following excess maternal fructose exposure. These underlying asymptomatic programmed pathways may lead to a predisposition to metabolic dysfunction later in life.

Sex-specific alterations in hepatic cholesterol metabolism in low birth weight adult guinea pigs.

BACKGROUND: Intrauterine growth restriction and low birth weight (LBW) have been widely reported as an independent risk factor for adult hypercholesterolaemia and increased hepatic cholesterol in a sex-specific manner. However, the specific impact of uteroplacental insufficiency (UPI), a leading cause of LBW in developed world, on hepatic cholesterol metabolism in later life, is ill defined and is clinically relevant in understanding later life liver metabolic health trajectories. METHODS: Hepatic cholesterol, transcriptome, cholesterol homoeostasis regulatory proteins, and antioxidant markers were studied in UPI-induced LBW and normal birth weight (NBW) male and female guinea pigs at 150 days. RESULTS: Hepatic free and total cholesterol were increased in LBW versus NBW males. Transcriptome analysis of LBW versus NBW livers revealed that "cholesterol metabolism" was an enriched pathway in LBW males but not in females. Microsomal triglyceride transfer protein and cytochrome P450 7A1 protein, involved in hepatic cholesterol efflux and catabolism, respectively, and catalase activity were decreased in LBW male livers. Superoxide dismutase activity was reduced in LBW males but increased in LBW females. CONCLUSIONS: UPI environment is associated with a later life programed hepatic cholesterol accumulation via impaired cholesterol elimination in a sex-specific manner. These programmed alterations could underlie later life cholesterol-induced hepatic lipotoxicity in LBW male offspring. IMPACT: Low birth weight (LBW) is a risk factor for increased hepatic cholesterol. Uteroplacental insufficiency (UPI) resulting in LBW increased hepatic cholesterol content, altered hepatic expression of cholesterol metabolism-related genes in young adult guinea pigs. UPI-induced LBW was also associated with markers of a compromised hepatic cholesterol elimination process and failing antioxidant system in young adult guinea pigs. These changes, at the current age studied, were sex-specific, only being observed in LBW males and not in LBW females. These programmed alterations could lead to further hepatic damage and greater predisposition to liver diseases in UPI-induced LBW male offspring as they age.

Differential and Synergistic Effects of Low Birth Weight and Western Diet on Skeletal Muscle Vasculature, Mitochondrial Lipid Metabolism and Insulin Signaling in Male Guinea Pigs.

Low birth weight (LBW) offspring are at increased risk for developing insulin resistance, a key precursor in metabolic syndrome and type 2 diabetes mellitus. Altered skeletal muscle vasculature, extracellular matrix, amino acid and mitochondrial lipid metabolism, and insulin signaling are implicated in this pathogenesis. Using uteroplacental insufficiency (UPI) to induce intrauterine growth restriction (IUGR) and LBW in the guinea pig, we investigated the relationship between UPI-induced IUGR/LBW and later life skeletal muscle arteriole density, fibrosis, amino acid and mitochondrial lipid metabolism, markers of insulin signaling and glucose uptake, and how a postnatal high-fat, high-sugar "Western" diet (WD) modulates these changes. Muscle of 145-day-old male LBW glucose-tolerant offspring displayed diminished vessel density and altered acylcarnitine levels. Disrupted muscle insulin signaling despite maintained whole-body glucose homeostasis also occurred in both LBW and WD-fed male "lean" offspring. Additionally, postnatal WD unmasked LBW-induced impairment of mitochondrial lipid metabolism, as reflected by increased acylcarnitine accumulation. This study provides evidence that early markers of skeletal muscle metabolic dysfunction appear to be influenced by the in utero environment and interact with a high-fat/high-sugar postnatal environment to exacerbate altered mitochondrial lipid metabolism, promoting mitochondrial overload.

Hepatic cytochrome P450 function is reduced by life-long Western diet consumption in guinea pig independent of birth weight.

INTRODUCTION: Non-alcoholic fatty liver disease (NAFLD) is characterised by accumulation of triglycerides and cholesterol within the liver and dysregulation of specific hepatic cytochrome P450 (CYPs) activity. CYPs are involved in the metabolism of endogenous and exogenous chemicals. Hepatic CYP activity is dysregulated in human studies and animal models of a Western diet (WD) or low birth weight (LBW) independently, but the additive effects of LBW and postnatal WD consumption are unknown. As such, the aim of this study was to determine the independent and combined effect of birthweight and postnatal diet on hepatic CYP activity in a guinea pig model. METHODS: LBW was generated via uterine artery ablation at mid gestation (term = 70 days gestation). Normal birthweight (NBW) and LBW pups were allocated either a control diet (CD) or WD at weaning. After 4 months of dietary intervention, guinea pigs were humanely killed, and liver tissue collected for biochemical and functional hepatic CYP activity analyses. RESULTS: Independent of birthweight, functional activity of CYP3A was significantly reduced in female and male WD compared to CD animals (female, P < 0.0001; male, P = 0.004). Likewise, CYP1A2 activity was significantly reduced in male WD compared to CD animals (P = 0.020) but this same reduction was not observed in females. CONCLUSION: Diet, but not birthweight, significantly altered hepatic CYP activity in both sexes, and the effect of diet appeared to be greater in males. These findings may have clinical implications for the management of NAFLD and associated co-morbidities between the sexes.

Quality of Life During Chemotherapy for Breast Cancer in a West African Population in Dakar, Senegal: A Prospective Study.

PURPOSE: The prevalence of breast cancer is increasing in low- to middle-income countries such as Senegal. Our prospective study assessed the quality of life (QoL) of patients with breast cancer undergoing chemotherapy in Senegal. PATIENTS AND METHODS: Our study included women with breast cancer undergoing chemotherapy as initial treatment at the Center Aristide Le Dantec University Hospital in Dakar. Clinical, sociodemographic, and QoL data were collected and analyzed at three different times: baseline, 3 months, and 6 months after the start of systemic therapy. Health-related QoL was assessed using a Functional Assessment of Cancer Therapies-Breast (FACT-B) questionnaire after translation into the Wolof language. Linear mixed-effects models were performed to assess the changes in QoL scores. RESULTS: Between July 2017 and February 2018, 120 patients were included in the study. Their median age was 45 years. Most patients (n = 105; 92%) had locally advanced disease (T3 to T4 stage) and lymph node involvement (n = 103; 88%), and half had metastatic disease. The FACT-B total scores significantly improved over time (ß = 1.58; 95% CI, 0.50 to 2.67; P < .01). Nausea and vomiting were significantly associated with a decrease in FACT-B total scores (ß = -16.89, 95% CI, -29.58 to -4.24, P = .012; and ß = -13.44, 95% CI, -25.15 to -1.72, P = .028, respectively). CONCLUSION: Our study confirmed the feasibility of standardized QoL assessment in Senegalese patients with breast cancer. Our results indicated a potential improvement of QoL over the course of chemotherapy. Optimizing nausea and vomiting prevention may improve QoL.

Reduced delta-6 desaturase activity partially protects against high-fat diet-induced impairment in whole-body glucose tolerance.

Delta-6 desaturase (D6D), which is encoded by the fatty acid desaturase (Fads2) gene, is the rate-limiting enzyme for the endogenous production of n-3 long-chain polyunsaturated fatty acids. The absence of D6D activity in Fads2-/- knockout mice results in the inability to produce eicosapentaenoic acid and docosahexaenoic acid, and has previously been associated with altered glucose and lipid metabolism. Skeletal muscle is a major site for insulin-stimulated glucose disposal; however, the consequences of reduced D6D activity on skeletal muscle metabolism are unknown. The objective of this study was to examine the role of a partial reduction in D6D activity on whole-body glucose tolerance, skeletal muscle fatty acid profiles and protein content of key markers of carbohydrate and fat signaling pathways in the context of both low- and high-fat diets. Male C57BL/6J heterozygous (Fads2+/-) and wild-type (WT) mice were fed either a low-fat (16% kcal from fat) or high-fat (HFD; 45% kcal from fat) diet for 21 weeks. Fads2+/- mice were protected from the HFD-induced impairment in glucose tolerance. Unexpectedly, HFD-fed Fads2+/- mice had reduced GLUT4 skeletal muscle protein content compared to their WT counterparts. No changes were detected in total protein content of key markers of fatty acid uptake, glycogen formation or substrate oxidation. This study shows that reduced D6D activity is partially protective against HFD-induced impairments in whole-body glucose tolerance but does not appear to be due to increased muscle GLUT4 content or total content of proteins regulating substrate utilization.

Western diet consumption through early life induces microvesicular hepatic steatosis in association with an altered metabolome in low birth weight Guinea pigs.

Uteroplacental insufficiency-induced low birth weight (LBW) and postnatal high saturated fat/high sucrose-fructose diet (Western Diet, WD) consumption have been independently associated with the development of hepatic steatosis, while their additive effect on fatty acid, acylcarnitine and amino acid profiles in early adulthood have not been widely reported. We employed LBW, generated via uterine artery ablation, and normal birth weight (NBW) male guinea pigs fed either a WD or control diet (CD) from weaning to postnatal day 150 (early adulthood). Hepatic steatosis was absent in CD-fed offspring, while NBW/WD offspring displayed macrovesicular steatosis and LBW/WD offspring exhibited microvesicular steatosis, both occurring in a lean phenotype. Life-long consumption of the WD, irrespective of birth weight, was associated with an increase in hepatic medium- and long-chain saturated fatty acids, monounsaturated fatty acids, acylcarnitines, reduced oxidative phosphorylation complex III activity and polyunsaturated fatty acids, and molecular evidence of disrupted hepatic insulin signaling. In NBW/WD, hepatic C15:1 and C16:1n-6 fatty acids in phospholipids, C16, C18 and C18:1 acylcarnitines, concentrations of aspartate, phenylalanine, tyrosine and tryptophan and expression of carnitine palmitoyltransferase 1 alpha (CPT1α) and uncoupling protein 2 (UCP2) genes were elevated compared to LBW/WD livers. Our results suggest that LBW and life-long WD combined are influential in promoting hepatic microvesicular steatosis in conjunction with a specific mitochondrial gene expression and metabolomic profile in early adulthood.

Dietary EPA and DHA prevent changes in white adipose tissue omega-3 PUFA and oxylipin content associated with a Fads2 deficiency.

Fatty acid desaturase 2 (Fads2) encodes the delta-6 desaturase (D6D) enzyme, which is rate-limiting for the endogenous production of omega-3 long-chain polyunsaturated fatty acids (LC-PUFA). Numerous studies have reported the cardiometabolic health benefits of omega-3 LC-PUFA. Humans carrying genetic variants in the FADS2 gene have reduced levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as well as oxylipins, in blood, erythrocytes and white adipose tissue (WAT). Similar findings have been reported in whole-body Fads2-/- mice fed a diet deficient in omega-3 LC-PUFA. The objective of this study was to determine if a diet containing EPA and DHA would prevent the deficiencies in WAT lipid profiles seen in Fads2-/- mice fed a diet containing only ALA. Male C57BL/6 J Fads2-/- and wild type (WT) mice were fed a low fat (7% w/w) diet for 9 weeks containing either flaxseed oil + ARASCO (FD, containing~53% ALA) or menhaden oil (MD, containing~14% EPA and 10% DHA). Fads2-/- mice fed an ALA-enriched diet had reduced body weight, little-to-no omega-3 LC-PUFA and a near complete loss of all omega-3 derived oxylipins in both epididymal and inguinal WAT (P<.05) compared to their WT counterparts, as well as altered expression of key regulators of the fatty acid desaturase pathway. However, Fads2-/- mice fed a diet containing EPA and DHA prevented most of these changes. This study provides evidence that a diet containing EPA and DHA provides a nutritional strategy to prevent alterations in WAT lipid content caused by reduced D6D activity.

Alpha-linolenic acid and linoleic acid differentially regulate the skeletal muscle secretome of obese Zucker rats.

Evidence shows that proteins secreted from skeletal muscle influence a broad range of metabolic signaling pathways. We previously reported that essential polyunsaturated fatty acids (PUFA) improved whole-body glucose homeostasis in obese Zucker rats; however, the mechanisms underlying these benefits remain enigmatic. While PUFA and obesity influence skeletal muscle function, their effects on the secretome are unknown. The aim of this work was to determine if improvements in whole-body glucose homeostasis in obese Zucker rats fed diets supplemented with either linoleic acid (LA) or alpha-linolenic acid (ALA) for 12 wk are related to changes in the skeletal muscle secretome. Secreted proteins were identified with a predictive bioinformatic analysis of microarray gene expression from red tibialis anterior skeletal muscle. Approximately 130 genes were differentially expressed (false discovery rate = 0.05) in obese rats compared with lean controls. The expression of 15 genes encoding secreted proteins was differentially regulated in obese controls, obese LA-supplemented, and obese ALA-supplemented rats compared with lean controls. Five secreted proteins ( Col3a1, Col15a1, Pdgfd, Lyz2, and Angptl4) were differentially regulated by LA and ALA. Most notably, ALA supplementation reduced Angptl4 gene expression compared with obese control and obese-LA supplemented rats and reduced circulating ANGPTL4 serum concentrations. ALA also influenced Angptl4 gene expression and ANGPTL4 secretion from differentiated rat L6 myotubes. Altogether, the present data indicate that obesity has a greater global impact on skeletal muscle gene expression than either essential PUFA; however, LA and ALA may exert their metabolic benefits in part by regulating the skeletal muscle secretome.

Neither linoleic acid nor arachidonic acid promote white adipose tissue inflammation in Fads2-/- mice fed low fat diets.

Dietary n-6 polyunsaturated fatty acids (PUFA) are widely perceived to promote inflammation and contribute to the development of chronic diseases. This dogma has been recently questioned due to evidence that n-6 PUFA, specifically linoleic acid (LA, 18:2n-6) and arachidonic acid (AA, 20:4n-6), do not appear to activate inflammatory signalling pathways when consumed in moderate amounts. However, delineating the independent roles of different dietary n-6 PUFA in vivo is challenging because LA is continuously converted into AA in a pathway regulated by the fatty acid desaturase 2 (Fads2) gene. The objective of this study was to investigate the independent roles of LA and AA on white adipose tissue (WAT) inflammatory signalling pathways using Fads2-/- mice. We hypothesized that dietary LA would not induce WAT inflammation, unless it was endogenously converted into AA. Male C57BL/6 wild-type (WT) and Fads2-/- mice were fed low-fat isocaloric diets containing either 7% corn oil w/w (CD, containing ~42% LA) or 7% ARASCO oil w/w (AD, containing ~27% AA) for 9 weeks. WAT inflammatory gene expression, protein levels, as well as phospholipid (PL) and triacylglycerol (TAG) fatty acid composition, were analyzed by RT-qPCR, western blots, and gas chromatography, respectively. Fads2-/- mice fed CD had high LA, but little-to-no GLA (18:3n-6), DGLA (20:3n-6), and AA in PLs and TAGs compared to their WT counterparts. In comparison, Fads2-/- and WT mice fed AD showed minimal differences in n-6 PUFA content in serum and WAT, despite having significantly more AA than CD-fed mice. No differences in gene expression for common inflammatory adipokines (e.g. Mcp-1, Ccl5, Tnfα) or key regulators of eicosanoid production (e.g. Cox-2, Alox-12, Alox-15) were detected in WAT between any of the diet and genotype groups. Furthermore, no differences in MCP-1, and total or phosphorylated STAT3 and p38 inflammatory proteins, were observed. Collectively, these results demonstrate that neither LA nor AA promote WAT inflammation when consumed as part of a low-fat diet. Therefore, the existing dogma surrounding n-6 PUFA and inflammation needs to be reconsidered.

Subcutaneous and Visceral Adipose Tissue Secretions from Extremely Obese Men and Women both Acutely Suppress Muscle Insulin Signaling.

Adipose tissue plays a key role in the development of type-2 diabetes via the secretion of adipokines. The current study investigated if secretion media derived from intact visceral (VAT) and subcutaneous (SAT) adipose tissues from extremely obese men and women differently suppressed insulin signaling in human skeletal myotubes derived from a healthy, non-diabetic male and female donor, respectively. Adipose tissue samples were collected from men and women during laparoscopic bariatric surgery. In general, secretion media collected from both SAT and VAT depots caused impaired insulin signaling in myotubes, independent of sex. In females, this was true regardless of the protein kinase B (Akt) phosphorylation site (Akt Thr308 and Akt Ser473) assessed (p < 0.01). In males, both SAT and VAT secretion media reduced Akt Thr308 activation in insulin-stimulated myotubes compared to controls (p < 0.001); however, only the VAT secretion media impaired Akt Ser473 phosphorylation. Independent of sex, 13 out of 18 detected cytokines, chemokines, and growth factors were more abundant in VAT versus SAT secretion media (p < 0.01). Both SAT and VAT secretion media from obese men and women acutely suppress insulin signaling in myotubes, despite different secretion profiles. We propose that this crosstalk model will help to extend our understanding of the interplay between adipose and muscle, as well as the pathogenesis of type-2 diabetes.

Impact of birth weight and postnatal diet on the gut microbiota of young adult guinea pigs.

BACKGROUND: The gastrointestinal tract (GIT) microbiota is essential to metabolic health, and the prevalence of the Western diet (WD) high in fat and sugar is increasing, with evidence highlighting a negative interaction between the GIT and WD, resulting in liver dysfunction. Additionally, an adverse in utero environment such as placental insufficiency resulting in low birth weight (LBW) offspring, contributes to an increased risk of metabolic diseases such as fatty liver infiltration and liver dysfunction in later life. We sought to understand the potential interactive effects of exposure to a WD upon growing LBW offspring. We postulated that LBW offspring when challenged with a poor postnatal diet, would display an altered microbiota and more severe liver metabolic dysfunction. METHODS: The fecal microbiota of normal birth weight (NBW) and LBW young guinea pig offspring, weaned onto either a control diet (CD) or WD was determined with 16S rRNA gene next generation sequencing at young adulthood following the early rapid growth phase after weaning. A liver blood chemistry profile was also performed. RESULTS: The life-long consumption of WD following weaning into young adulthood resulted in increased total cholesterol, triglycerides and alanine aminotransferase levels in association with an altered GIT microbiota when compared to offspring consuming CD. Neither birth weight nor sex were associated with any significant changes in microbiota alpha diversity, by measuring the Shannon's diversity index. One hundred forty-eight operational taxonomic units were statistically distinct between the diet groups, independent of birth weight. In the WD group, significant decreases were detected in Barnesiella, Methanobrevibacter smithii and relatives of Oscillospira guillermondii, while Butyricimonas and Bacteroides spp. were increased. DISCUSSION: These results describe the GIT microbiota in a guinea pig model of LBW and WD associated metabolic syndrome and highlight several WD specific GIT alterations associated with human metabolic disease.

[Letter to the Editor] Protein phosphorylation status is preserved following dual RNA and protein extraction using the Qiagen RNeasy Mini Kit.

Address correspondence to David M. Mutch, Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G 2W1 Canada. E-mail: dmutch@uoguelph.ca.

The differential effects of low birth weight and Western diet consumption upon early life hepatic fibrosis development in guinea pig.

Postnatal intake of an energy dense diet, the Western diet (WD), is a strong risk factor for liver fibrosis. Recently, adverse in utero conditions resulting in low birth weight (LBW) have also been associated with postnatal fibrosis development. We assessed the independent and possible synergistic effects of placental insufficiency-induced LBW and postnatal WD consumption on liver fibrosis in early adulthood, with a specific focus on changes in inflammation and apoptosis pathways in association with fibrogenesis. Male LBW (uterine artery ablation) and normal birth weight (NBW) guinea pig pups were fed either a control diet (CD) or WD from weaning to 150 days. Significant steatosis, mild lobular inflammation, apoptosis and mild stage 1 fibrosis (perisinusoidal or portal) were evident in WD-fed offspring (NBW/WD and LBW/WD). In LBW/CD versus NBW/CD offspring, increased transforming growth factor-beta 1 and matrix metallopeptidase mRNA and sma- and Mad-related protein 4 (SMAD4) were present in conjunction with minimal stage 1 portal fibrosis. Further, connective tissue growth factor mRNA was increased and miR-146a expression decreased in LBW offspring, irrespective of diet. Independent of birth weight, WD-fed offspring exhibited increased expression of fibrotic genes as well as elevated inflammatory and apoptotic markers. Moreover, the augmented expression of collagen, type III, alpha 1 and tumor necrosis factor-alpha was associated with increased recruitment of RNA polymerase II and enhanced histone acetylation (K9) to their respective promoters. These data support a role for both LBW and postnatal WD as factors contributing to hepatic fibrosis development in offspring through distinct pathways.

Low birth weight followed by postnatal over-nutrition in the guinea pig exposes a predominant player in the development of vascular dysfunction.

The association between intrauterine growth restriction (IUGR) and hypertension is well established, yet the interaction between IUGR and other pathogenic contributors remains ill-defined. This study examined the independent and interactive effects of fetal growth reduction resulting in low birth weight (LBW), and postnatal Western diet (WD) on vascular function. Growth reduction was induced in pregnant guinea pigs by uterine artery ablation. LBW and normal birth weight (NBW) offspring were randomly assigned to a control diet (CD) or a WD. In young adulthood, length-tension curves were generated in aortic rings and responses to methacholine (MCh) were evaluated in the carotid and aorta using wire myography. Relative to NBW/CD, aortae of NBW/WD offspring were stiffer, as determined by a leftward shift in the length-tension curve, yet the shift in the LBW/CD curve was considerably greater. Aortic stiffening was most severe in LBW/WD (slope: NBW/CD, 1.97 ± 0.04; NBW/WD, 2.16 ± 0.04; LBW/CD, 2.28 ± 0.05; LBW/WD, 2.34 ± 0.07). Maximal responses (Emax) to MCh were significantly blunted in the aorta of LBW/CD vs. NBW/CD (P < 0.05) and in LBW/WD vs. NBW/WD offspring (P < 0.05); but WD alone had no influence on MCh responses. Emax values for carotid responses to MCh were reduced in LBW/CD vs. NBW/CD (P < 0.05). Thus, aortic stiffening was influenced more by LBW than by a postnatal WD and the most severe stiffening was observed in LBW/WD offspring. In contrast, blunted endothelial responses in LBW/CD offspring were not exacerbated by WD. IUGR may have a greater independent impact on vascular function than a postnatal WD.