Implication of low level inflammation in the insulin resistance of adipose tissue at late pregnancy

Beta-cell compensation and gestational diabetes

Gestational diabetes mellitus (GDM) is characterized by glucose intolerance in pregnant women without a previous diagnosis of diabetes. While the etiology of GDM remains elusive, the close association of GDM with increased maternal adiposity and advanced gestational age implicates insulin resistance as a culpable factor for the pathogenesis of GDM. Pregnancy is accompanied by the physiological induction of insulin resistance in the mother secondary to maternal weight gain. This effect serves to spare blood glucose for the fetus. To overcome insulin resistance, maternal β-cells are conditioned to release more insulin into the blood. Such an adaptive response, termed β-cell compensation, is essential for maintaining normal maternal metabolism. β-cell compensation culminates in the expansion of β-cell mass and augmentation of β-cell function, accounting for increased insulin synthesis and secretion. As a result, a vast majority of mothers are protected from developing GDM during pregnancy. In at-risk pregnant women, β-cells fail to compensate for maternal insulin resistance, contributing to insulin insufficiency and GDM. However, gestational β-cell compensation ensues in early pregnancy, prior to the establishment of insulin resistance in late pregnancy. How β-cells compensate for pregnancy and what causes β-cell failure in GDM are subjects of investigation. In this mini-review, we will provide clinical and preclinical evidence that β-cell compensation is pivotal for overriding maternal insulin resistance to protect against GDM. We will highlight key molecules whose functions are critical for integrating gestational hormones to β-cell compensation for pregnancy. We will provide mechanistic insights into β-cell decompensation in the etiology of GDM.

Selenium Prevents Inflammation in Human Placenta and Adipose Tissue In Vitro: Implications for Metabolic Diseases of Pregnancy Associated with Inflammation

Gestational diabetes mellitus (GDM) and maternal obesity are significant metabolic complications increasingly prevalent in pregnancy. Of major concern, both GDM and maternal obesity can have long-term detrimental impacts on the health of both mother and offspring. Recent research has shown that increased inflammation and oxidative stress are two features central to the pathophysiology of these metabolic conditions. Evidence suggests selenium supplementation may be linked to disease prevention in pregnancy; however, the specific effects of selenium on inflammation and oxidative stress associated with GDM and maternal obesity are unknown. Therefore, this study aimed to investigate the effect of selenium supplementation on an in vitro model of GDM and maternal obesity. Human placental tissue, visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were stimulated with either the bacterial product lipopolysaccharide (LPS) or the pro-inflammatory cytokine TNF-α. Selenium pre-treatment blocked LPS and TNF-α induced mRNA expression and secretion of pro-inflammatory cytokines and chemokines, while increasing anti-inflammatory cytokine and antioxidant mRNA expression in placenta, VAT and SAT. Selenium pre-treatment was also found to inhibit LPS- and TNF-α induced phosphorylation of ERK in placenta, VAT and SAT. These findings indicate that selenium may be able to prevent inflammation and oxidative stress associated with GDM and maternal obesity. Additional in vivo studies are required to identify the efficacy of selenium supplementation in preventing inflammatory pathways activated by GDM and maternal obesity and to elucidate the mechanism involved.

Relationships between adiposity distribution and metabolic health in preconception women in South Africa

Objective

Adipose tissue is a central regulator of metabolic health and a contributor to systemic inflammation. Patterns of adiposity deposition are important to understand for optimizing health. This study aimed to asses relationships between adiposity deposition and metabolic and inflammatory biomarkers in South African women prior to conception.

Methods

Non‐pregnant, healthy women (n = 298) were recruited for this cross‐sectional study via home visits. Body composition was measured by Dual X‐ray Absorptiometry. Inflammation markers C‐reactive protein (CRP), alpha1‐acid glycoprotein (AGP), hemoglobin A1c (HbA1c), and blood pressure were scored according to risk. A summative metabolic health risk score was created for women with obesity. Generalized regression models assessed relationships between adiposity deposition and outcomes with adjustment for potential confounders.

Results

Obesity was present in 22% of women (mean age = 20.93 years). Fat mass index was associated with inflammation and metabolic health risk (β = 0.58; p < 0.01). Visceral fat, trunk:limb ratio, android:gynoid ratio, body mass index, weight, and waist circumference were positively associated with CRP, AGP, and metabolic health risk (p < 0.01). Weight was associated with Hba1c (β < 0.01; p < 0.05). Participants with obesity and low metabolic health risk had lower fat mass index and visceral fat than participants with obesity and higher metabolic health risk.

Conclusions

Black South African women accumulated excess adipose tissue in abdominal regions. While fat mass and body mass were associated with inflammation and metabolic health risk, women with obesity and with lower fat mass index and lower visceral adipose tissue were metabolically protected. Identification of women at risk for metabolic disease preconception could help ensure future healthy pregnancies and prevent transference of risk to offspring.

Dietary β-Carotene on Postpartum Uterine Recovery in Mice: Crosstalk Between Gut Microbiota and Inflammation

As the precursor of vitamin A, β-carotene has a positive effect on reproductive performance. Our previous study has shown that β-carotene can increase antioxidant enzyme activity potentially through regulating gut microbiota in pregnant sows. This study aimed to clarify the effect of β-carotene on reproductive performance and postpartum uterine recovery from the aspect of inflammation and gut microbiota by using a mouse model. Twenty-seven 6 weeks old female Kunming mice were randomly assigned into 3 groups (n=9), and fed with a diet containing 0, 30 or 90 mg/kg β-carotene, respectively. The results showed that dietary supplementation of β-carotene reduced postpartum uterine hyperemia and uterine mass index (P<0.05), improved intestinal villus height and villus height to crypt depth ratio, decreased serum TNF-α and IL-4 concentration (P<0.05), while no differences were observed in litter size and litter weight among three treatments. Characterization of gut microbiota revealed that β-carotene up-regulated the relative abundance of genera Akkermansia, Candidatus Stoquefichus and Faecalibaculum, but down-regulated the relative abundance of Alloprevotella and Helicobacter. Correlation analysis revealed that Akkermansia was negatively correlated with the IL-4 concentration, while Candidatus Stoquefichus and Faecalibaculum had a negative linear correlation with both TNF-α and IL-4 concentration. On the other hand, Alloprevotella was positively correlated with the TNF-α, and Helicobacter had a positive correlation with both TNF-α and IL-4 concentration. These data demonstrated that dietary supplementation of β-carotene contributes to postpartum uterine recovery by decreasing postpartum uterine hemorrhage and inhibiting the production of inflammatory cytokines potentially through modulating gut microbiota.

Role of Receptor Protein Tyrosine Phosphatases (RPTPs) in Insulin Signaling and Secretion

Changes in lifestyle in developed countries have triggered the prevalence of obesity and type 2 diabetes mellitus (T2DM) in the latest years. Consequently, these metabolic diseases associated to insulin resistance, and the morbidity associated with them, accounts for enormous costs for the health systems. The best way to face this problem is to identify potential therapeutic targets and/or early biomarkers to help in the treatment and in the early detection. In the insulin receptor signaling cascade, the activities of protein tyrosine kinases and phosphatases are coordinated, thus, protein tyrosine kinases amplify the insulin signaling response, whereas phosphatases are required for the regulation of the rate and duration of that response. The focus of this review is to summarize the impact of transmembrane receptor protein tyrosine phosphatase (RPTPs) in the insulin signaling cascade and secretion, and their implication in metabolic diseases such as obesity and T2DM.

Undernutrition induces major alterations in the lipid droplets of white and brown adipose tissues in wistar rats

Several studies have shown a relationship between the distribution of fat mass around the organism, metabolic disorders, and an increased risk of morbidity and mortality. It has been demonstrated that in obese animals there is a big rise in the white fat deposits due to hyperplasia and hypertrophy of the adipocytes. Studies related to weight and health have been more popular regarding obesity rather than extreme caquexia or calorico-proteic deficiencies, but these states are interesting from the point of view of the preferential atrophy of certain organs that may help us in the understanding of undernourishment. Moreover, the discovery of beige adipose tissue has instigated thoughts around the roles played by the different cells in the adipose tissue as well as its adaptability in pathological states. In our study we carried out morphometric, morphological, and quantitative measurements of the adipose tissue in an animal model based on a 40-50% diet restriction in comparison to control animals. We have found a decrease in the size of white adipocytes together with a variation in the lipid droplet size of brown adipocytes in undernourished animals, what may be considered as possible transformations between the types of adipose tissues, and that could be caused by an adaptive phenomenon to the undernourished state.

Anti-inflammatory effects of phenolic acids punicalagin and curcumin in human placenta and adipose tissue

INTRODUCTION

The world is witnessing a steady rise in the prevalence of gestational diabetes mellitus (GDM), correlated with the current obesity epidemic. Both GDM and obesity negatively impact both the health of women but also that of the next generation. GDM and maternal obesity are associated with increased maternal and fetal inflammation and oxidative stress. A safe and effective intervention that can prevent these pathological features, and reduce the intergenerational burden, is required. Phenolic acids, such as punicalagin and curcumin, possess anti-inflammatory and antioxidant properties. Thus, the aim of this study was to examine the effects of punicalagin and curcumin on pro-inflammatory cytokines and chemokines, and antioxidant expression in an in vitro model of inflammation.

METHODS

Human placenta, visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) explants were obtained at term elective Caesarean section and stimulated with TNF alpha (TNF).

RESULTS

We found that punicalagin and curcumin significantly supressed TNF-induced pro-inflammatory cytokine (IL1A, IL1B, and IL6) and chemokine (CCL2-4, CXCL1, CXCL5 and CXCL8) expression in human placenta, VAT and SAT. Anti-inflammatory cytokine IL4 and IL13 mRNA expression was also upregulated by punicalagin and curcumin treatment in placenta, VAT and SAT. Punicalagin and curcumin also altered antioxidant (SOD2 and catalase) mRNA expression in placenta, VAT and SAT, with minimal effect on hydrogen peroxide concentrations in tissue lysates.

CONCLUSION

These findings suggest that the phenolic acids punicalagin and curcumin possess potent anti-inflammatory capabilities in in vitro human models of inflammation. Further studies are warranted to determine their suitability as therapeutic interventions for pro-inflammatory gestational complications, including GDM and maternal obesity.

The Effect of a Maternal Mediterranean Diet in Pregnancy on Insulin Resistance is Moderated by Maternal Negative Affect

There is inconsistent evidence that healthy dietary interventions can effectively mitigate the risk of adverse outcomes associated with elevated insulin resistance in pregnancy, suggesting that other moderating factors may be at play. Maternal psychological state is an important factor to consider in this regard, because stress/mood state can directly influence glycemia and a bidirectional relationship may exist between nutrition and psychological state. The objective of this study was to examine the interaction between maternal negative affect and diet quality on third trimester insulin resistance. We conducted a prospective longitudinal study of N = 203 women with assessments in early and mid-pregnancy, which included an ecological momentary assessment of maternal psychological state, from which a negative affect score (NAS) was derived, and 24-h dietary recalls, from which the Mediterranean Diet Score (MDS) was computed. The homeostasis model assessment of insulin resistance (HOMA-IR) was computed from third trimester fasting plasma glucose and insulin values. Early pregnancy MDS was inversely associated with the HOMA-IR, but this did not maintain significance after adjusting for covariates. There was a significant effect of the mid-pregnancy MDS*NAS interaction term with the HOMA-IR in the adjusted model, such that a higher negative affect was found to override the beneficial effects of a Mediterranean diet on insulin resistance. These results highlight the need to consider nutrition and affective state concurrently in the context of gestational insulin resistance.

IL-1β and IL-10 gene polymorphisms in women with gestational diabetes

AIMS

Gestational diabetes (GDM) is carbohydrate intolerance occurring in pregnant women. In the GDM pathogenesis, the low-grade inflammation plays a significant role. Various inflammatory mediators are considered to be risk factors leading to GDM development including cytokines. Studies suggest that some cytokines such as: IL-1β and IL-10 play an important role in GDM pathogenesis. The aim of the study was to examine the associations between IL-1β rs16944, and IL-10 rs1800872 gene polymorphisms and GDM.

METHODS

This study included 204 pregnant women with GDM and 207 pregnant women with normal glucose tolerance. The diagnosis of GDM was based on a 75-g oral glucose tolerance test administered at 24-28 weeks' gestation. Among the pregnant women with GDM, 152 (75%) were treated with diet control alone throughout the pregnancy, whereas the remaining 52 (25%) were treated with diet control and insulin until delivery.

RESULTS

There were no statistically significant differences in the distribution of IL-1β rs16944 and IL-10 rs1800872 between GDM and healthy women. However among women treated with insulin, we observed the increased frequency of IL-1β rs16944 AA genotype carriers. Additionally, we observed increased daily insulin requirement in women with IL-1β rs16944 AA genotype. Moreover, women with IL-10 rs1800872 AA genotype had higher body mass and BMI before pregnancy as well as higher body mass and BMI increase during pregnancy.

CONCLUSIONS

The results of our study suggest the association between IL-1β rs16944 AA genotype and increased frequency of the need of insulin treatment as well as increased daily insulin requirement.

Obeticholic acid ameliorates dyslipidemia but not glucose tolerance in mouse model of gestational diabetes

Metabolism alters markedly with advancing gestation, characterized by progressive insulin resistance, dyslipidemia, and raised serum bile acids. The nuclear receptor farnesoid X receptor (FXR) has an integral role in bile acid homeostasis and modulates glucose and lipid metabolism. FXR is known to be functionally suppressed in pregnancy. The FXR agonist, obeticholic acid (OCA), improves insulin sensitivity in patients with type 2 diabetes with nonalcoholic fatty liver disease. We therefore hypothesized that OCA treatment during pregnancy could improve disease severity in a mouse model of gestational diabetes mellitus (GDM). C57BL/6J mice were fed a high-fat diet (HFD; 60% kcal from fat) for 4 wk before and throughout pregnancy to induce GDM. The impact of the diet supplemented with 0.03% OCA throughout pregnancy was studied. Pregnant HFD-fed mice displayed insulin resistance and dyslipidemia. OCA significantly reduced plasma cholesterol concentrations in nonpregnant and pregnant HFD-fed mice (by 22.4%, P < 0.05 and 36.4%, P < 0.001, respectively) and reduced the impact of pregnancy on insulin resistance but did not change glucose tolerance. In nonpregnant HFD-fed mice, OCA ameliorated weight gain, reduced mRNA expression of inflammatory markers in white adipose tissue, and reduced plasma glucagon-like peptide 1 concentrations (by 62.7%, P < 0.01). However, these effects were not evident in pregnant mice. OCA administration can normalize plasma cholesterol levels in a mouse model of GDM. However, the absence of several of the effects of OCA in pregnant mice indicates that the agonistic action of OCA is not sufficient to overcome many metabolic consequences of the pregnancy-associated reduction in FXR activity.

Apolipoprotein A-I Protects Against Pregnancy-Induced Insulin Resistance in Rats

Objective- Insulin resistance and inflammation in pregnancy are risk factors for gestational diabetes mellitus. Increased plasma HDL (high-density lipoprotein) and apo (apolipoprotein) A-I levels have been reported to improve glucose metabolism and inhibit inflammation in animals and humans. This study asks whether increasing plasma apoA-I levels improves insulin sensitivity and reduces inflammation in insulin-resistant pregnant rats. Approach and Results- Insulin-resistant pregnant rats received intravenous infusions of lipid-free apoA-I (8 mg/kg) or saline on days 6, 9, 12, 15, and 18 of pregnancy. The rats were then subjected to a euglycemic-hyperinsulinemic clamp. Glucose uptake was increased in white and brown adipose tissue by 57±13% and 32±10%, respectively ( P<0.05 for both), and in quadriceps and gastrocnemius muscle by 35±9.7% and 47±14%, respectively ( P<0.05 for both), in the apoA-I-treated pregnant rats relative to saline-infused pregnant rats. The pregnant rats that were treated with apoA-I also had reduced plasma TNF-α (tumor necrosis factor-α) levels by 57±8.4%, plasma IL (interleukin)-6 levels by 67±9.5%, and adipose tissue macrophage content by 54±8.2% ( P<0.05 for all) relative to the saline-treated pregnant rats. Conclusions- These studies establish that apoA-I protects against pregnancy-induced insulin resistance in rats by increasing insulin sensitivity in adipose tissue and skeletal muscle and inhibiting inflammation. This identifies apoA-I as a potential target for preventing pregnancy-induced insulin resistance and reducing the incidence of gestational diabetes mellitus.

Connecting Metainflammation and Neuroinflammation Through the PTN-MK-RPTPβ/ζ Axis: Relevance in Therapeutic Development

Inflammation is a common factor of pathologies such as obesity, type 2 diabetes or neurodegenerative diseases. Chronic inflammation is considered part of the pathogenic mechanisms of different disorders associated with aging. Interestingly, peripheral inflammation and the associated metabolic alterations not only facilitate insulin resistance and diabetes but also neurodegenerative disorders. Therefore, the identification of novel pathways, common to the development of these diseases, which modulate the immune response and signaling is key. It will provide highly relevant information to advance our knowledge of the multifactorial process of aging, and to establish new biomarkers and/or therapeutic targets to counteract the underlying chronic inflammatory processes. One novel pathway that regulates peripheral and central immune responses is triggered by the cytokines pleiotrophin (PTN) and midkine (MK), which bind its receptor, Receptor Protein Tyrosine Phosphatase (RPTP) β/ζ, and inactivate its phosphatase activity. In this review, we compile a growing body of knowledge suggesting that PTN and MK modulate the immune response and/or inflammation in different pathologies characterized by peripheral inflammation associated with insulin resistance, such as aging, and in central disorders characterized by overt neuroinflammation, such as neurodegenerative diseases and endotoxemia. Evidence strongly suggests that regulation of the PTN and MK signaling pathways may provide new therapeutic opportunities particularly in those neurological disorders characterized by increased PTN and/or MK cerebral levels and neuroinflammation. Importantly, we discuss existing therapeutics, and others being developed, that modulate these signaling pathways, and their potential use in pathologies characterized by overt neuroinflammation.

Exercise as a therapeutic intervention to optimize fetal weight

The Developmental Origins of Health and Disease suggest the in utero environment programs offspring obesity and cardiovascular disease. Therefore, there is a need to implement safe therapeutic interventions that do not involve the intake of medications or biological products during pregnancy that can improve maternal and fetal health. Prenatal exercise is established to promote maternal and fetal health. It is generally recommended that women accumulate at least 150 min per week of moderate-intensity exercise. It has been demonstrated that prenatal exercise maintains healthy weight gain and improves maternal glucose control, maternal cardiac autonomic control, placental efficiency (increases angiogenesis, downregulates genes involved in fatty acid transport and insulin transport across the placenta, and upregulates genes involved in amino acid transport across the placenta), and oxidative stress. These adaptations following exercise improve maternal metabolism and provide adequate uteroplacental perfusion. In this review, we will focus on exercise as a therapeutic intervention to optimize fetal weight. It has been established that prenatal exercise does not increase the risk of having a small for gestational age baby. To the contrary, prenatal exercise has been associated with the prevention of excessive fat accumulation in the newborn and the maintenance of fetal muscle mass.

Omentectomy Prevents Metabolic Syndrome By Reducing Appetite and Body Weight In A Diet-Induced Obesity Rat Model

Visceral fat deposition is associated with impairment of glucose and lipid metabolism while leptin levels are frequently related to subcutaneous fat area. At present, there is considerable controversy regarding the role of visceral adipose tissue accumulation in the development of metabolic syndrome (MS). Here we show the effects of omentectomy on the liver and MS in a diet induced obesity rat model. Our results reveal that undergoing omentectomy previously the establishment of the diet-induced-obesity reduced significantly body weight gain and avoid the development of MS, including non-alcoholic fatty liver disease. Intriguingly, the significantly lower body weight gain was due to decreased food intake. Omentum drives obesity progression through leptin resistance mediated by C-reactive protein, Interleucin (IL)-6 and high lipolysis activity. Omentum removal reversed immediately the increased plasma levels of CRP and IL-6 and gradually food intake, weight gain, and features of MS in diet-induced-obesity. Omentectomy caused no changes in normal-weigh-rats. This report displays causal mechanism by which omentum promotes obesity and propose omentectomy as a promising procedure in MS prevention.

Peripheral Neuroimmunoendocrine Interactions: Contribution of TNFRp55 to the Circadian Synchronization of Progesterone and Cytokine Production in Joints of Mice in Late Pregnancy

OBJECTIVE

Circadian rhythms are generated by the suprachiasmatic nucleus of the hypothalamus and involve rhythmic expression of clock genes and proteins. This rhythmicity is transferred to peripheral tissues by neural and hormonal signals. Late pregnancy is considered a state of inflammation which impacts on peripheral tissues such as joints. Tumor necrosis factor (TNF) mediates inflammatory and circadian responses through its p55 receptor (TNFRp55). Neuroimmunoendocrine interactions in joints have not been studied completely. The purpose of this study was to analyze these interactions, investigating the circadian rhythms of progesterone (Pg) and pro- and anti-inflammatory cytokines in the joints at the end of pregnancy (gestational day 18). Moreover, the impact of TNFRp55 deficiency on these temporal oscillations was explored.

METHODS

Wild-type and TNFRp55-deficient (KO) C57BL/6 mice were kept under constant darkness in order to study their endogenous circadian rhythms. The expression of the clock genes Bmal1 and Per1 at circadian time 7 was studied by reverse transcription polymerase chain reaction in the ankle joints of nonpregnant and pregnant (gestational day 18) mice. In late pregnancy, Pg and the cytokines interleukin 17 (IL-17), IL-6, and IL-10 were measured in the joints throughout a 24-h period by radioimmunoassay and enzyme-linked immunosorbent assay, respectively.

RESULTS

A significant increase in Bmal1 and Per1 mRNA expression was detected in the joints of pregnant KO mice. Furthermore, KO mice displayed a desynchronization of articular Pg and cytokine production.

CONCLUSIONS

Our results show that TNF, via TNFRp55 signaling, modulates articular Pg and cytokine circadian rhythms in late pregnancy. These findings suggest a temporal neuroimmunoendocrine association in peripheral tissues in late pregnancy.

Loss of Anticontractile Effect of Perivascular Adipose Tissue on Pregnant Rats: A Potential Role of Tumor Necrosis Factor-α

The present investigation examined the effect of pregnancy on the anticontractile effect of perivascular adipose tissue (PVAT) on the rat. Ring segments of the aorta, with and without PVAT, were set up in organ baths for isometric tension recording. In both groups, concentration-response curves to 5-hydroxytryptamine (5-HT) were displaced to the right with a reduction of the maximum response in aorta segments with PVAT. The anticontractile effect of PVAT was attenuated on segments from pregnant rats. 4-Aminopyridine (4-AP), an inhibitor of voltage-gated potassium (Kv) channels, enhanced 5-HT-induced contractions of aorta segments from pregnant and nonpregnant rats only when PVAT was attached. There was no difference in the effect of 4-aminopyridine on 5-HT-induced contractions of aorta segments with PVAT from pregnant and nonpregnant rats. There was also no significant difference in the expression of Kv7.4 channels in aorta segments (with PVAT) between pregnant and nonpregnant rats. Tumor necrosis factor-α (TNF-α) was detected in PVAT from pregnant and nonpregnant rats. The level of TNF-α was significantly greater in PVAT from pregnant rats. Treatment of pregnant rats with pentoxyphyline significantly reduced the level of TNF-α in the PVAT and restored the anticontractile effect of PVAT on aorta segments from pregnant rats. Finally, TNF-α (10 ng/mL) potentiated 5-HT-induced contractions of PVAT-containing pregnant rat aorta. These results would suggest that the loss of anticontractile effect of PVAT in pregnant rat aorta could be due to enhanced production of TNF-α in the PVAT in these rats.

Peroxisome proliferator activated receptor gamma 2 modulates late pregnancy homeostatic metabolic adaptations

Pregnancy requires the adaptation of maternal energy metabolism including expansion and functional modifications of adipose tissue. Insulin resistance (IR), predominantly during late gestation, is a physiological metabolic adaptation that serves to support the metabolic demands of fetal growth. The molecular mechanisms underlying these adaptations are not fully understood and may contribute to gestational diabetes mellitus. Peroxisome proliferator-activated receptor gamma (PPARγ) controls adipogenesis, glucose and lipid metabolism and insulin sensitivity. The PPARγ2 isoform is mainly expressed in adipocytes and is thus likely to contribute to adipose tissue adaptation during late pregnancy. In the present study, we investigated the contribution of PPARγ2 to the metabolic adaptations occurring during the late phase of pregnancy in the context of IR. Using a model of late pregnancy in PPARγ2 knockout (KO) mice, we found that deletion of PPARγ2 exacerbated IR in association with lower serum adiponectin levels, increased body weight and enhanced lipid accumulation in liver. Lack of PPARγ2 provoked changes in the distribution of fat mass and preferentially prevented the expansion of the perigonadal depot while at the same time exacerbating inflammation. PPARγ2KO pregnant mice presented adipose tissue depot-dependent decreased expression of genes involved in lipid metabolism. Collectively, these data indicate that PPARγ2 is essential to promote healthy adipose tissue expansion and immune and metabolic functionality during pregnancy, contributing to the physiological adaptations that lead gestation to term.

Altered cytokine network in gestational diabetes mellitus affects maternal insulin and placental-fetal development

Pregnancy is characterized by an altered inflammatory profile, compared to the non-pregnant state with an adequate balance between pro-and anti-inflammatory cytokines needed for normal development. Cytokines are small secreted proteins expressed mainly in immunocompetent cells in the reproductive system. From early developmental stages onward, the secretory activity of placenta cells clearly contributes to increase local as well as systemic levels of cytokines. The placental production of cytokines may affect mother and fetus independently. In turn because of this unique position at the maternal fetal interface, the placenta is also exposed to the regulatory influence of cytokines from maternal and fetal circulations, and hence, may be affected by changes in any of these. Gestational diabetes mellitus (GDM) is associated with an overall alteration of the cytokine network. This review discusses the changes that occur in cytokines post GDM and their negative effects on maternal insulin and placental-fetal development.

Characterization of Visceral and Subcutaneous Adipose Tissue Transcriptome and Biological Pathways in Pregnant and Non-Pregnant Women: Evidence for Pregnancy-Related Regional-Specific Differences in Adipose Tissue

Objective

The purpose of this study was to compare the transcriptome of visceral and subcutaneous adipose tissues between pregnant and non-pregnant women.

Study Design

The transcriptome of paired visceral and abdominal subcutaneous adipose tissues from pregnant women at term and matched non-pregnant women (n = 11) was profiled with the Affymetrix Human Exon 1.0 ST array. Differential expression of selected genes was validated with the use of quantitative reverse transcription–polymerase chain reaction.

Results

Six hundred forty-four transcripts from 633 known genes were differentially expressed (false discovery rate (FDR) <0.1; fold-change >1.5), while 42 exons from 36 genes showed differential usage (difference in FIRMA scores >2 and FDR<0.1) between the visceral and subcutaneous fat of pregnant women. Fifty-six known genes were differentially expressed between pregnant and non-pregnant subcutaneous fat and three genes in the visceral fat. Enriched biological processes in the subcutaneous adipose tissue of pregnant women were mostly related to inflammation.

Conclusion

The transcriptome of visceral and subcutaneous fat depots reveals pregnancy-related gene expression and splicing differences in both visceral and subcutaneous adipose tissue. Furthermore, for the first time, alternative splicing in adipose tissue has been associated with regional differences and human parturition.

The endocrine dyscrasia that accompanies menopause and andropause induces aberrant cell cycle signaling that triggers re-entry of post-mitotic neurons into the cell cycle, neurodysfunction, neurodegeneration and cognitive disease

This article is part of a Special Issue "SBN 2014". Sex hormones are physiological factors that promote neurogenesis during embryonic and fetal development. During childhood and adulthood these hormones support the maintenance of brain structure and function via neurogenesis and the formation of dendritic spines, axons and synapses required for the capture, processing and retrieval of information (memories). Not surprisingly, changes in these reproductive hormones that occur with menopause and during andropause are strongly correlated with neurodegeneration and cognitive decline. In this connection, much evidence now indicates that Alzheimer's disease (AD) involves aberrant re-entry of post-mitotic neurons into the cell cycle. Cell cycle abnormalities appear very early in the disease, prior to the appearance of plaques and tangles, and explain the biochemical, neuropathological and cognitive changes observed with disease progression. Intriguingly, a recent animal study has demonstrated that induction of adult neurogenesis results in the loss of previously encoded memories while decreasing neurogenesis after memory formation during infancy mitigated forgetting. Here we review the biochemical, epidemiological and clinical evidence that alterations in sex hormone signaling associated with menopause and andropause drive the aberrant re-entry of post-mitotic neurons into an abortive cell cycle that leads to neurite retraction, neuron dysfunction and neuron death. When the reproductive axis is in balance, gonadotropins such as luteinizing hormone (LH), and its fetal homolog, human chorionic gonadotropin (hCG), promote pluripotent human and totipotent murine embryonic stem cell and neuron proliferation. However, strong evidence supports menopausal/andropausal elevations in the LH:sex steroid ratio as driving aberrant mitotic events. These include the upregulation of tumor necrosis factor; amyloid-β precursor protein processing towards the production of mitogenic Aβ; and the activation of Cdk5, a key regulator of cell cycle progression and tau phosphorylation (a cardinal feature of both neurogenesis and neurodegeneration). Cognitive and biochemical studies confirm the negative consequences of a high LH:sex steroid ratio on dendritic spine density and human cognitive performance. Prospective epidemiological and clinical evidence in humans supports the premise that rebalancing the ratio of circulating gonadotropins:sex steroids reduces the incidence of AD. Together, these data support endocrine dyscrasia and the subsequent loss of cell cycle control as an important etiological event in the development of neurodegenerative diseases including AD, stroke and Parkinson's disease.

High levels of chorionic gonadotrophin attenuate insulin sensitivity and promote inflammation in adipocytes

Gestational diabetes mellitus (GDM) presents with moderate inflammation, insulin resistance and impaired glucose uptake, which may result from increased maternal fat mass and increased circulation of placental hormones and adipokines. In this study, we set out to test whether the surge in chorionic gonadotrophin (CG) secretion is a cause of inflammation and impaired insulin sensitivity in GDM. We first found that LH/chorionic gonadotrophin receptors (CG/LHR) were expressed at low levels in insulin-sensitive murine 3T3-L1 adipocytes and murine C2C12 myocytes. CG treatment not only directly reduced insulin-responsive gene expression, including that of glucose transporter 4 (GLUT4), but also impaired insulin-stimulated glucose uptake in 3T3-L1 cells. Moreover, CG treatment increased the expression of the proinflammatory cytokine monocyte chemotactic protein 1 (MCP1) and upregulated nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) activity in 3T3-L1 cells. Clinically, pregnant women who had higher CG levels and elevated MCP1 developed GDM. Above all, apart from prepregnancy BMI and MCP1 level, CG level was associated with abnormal glucose tolerance. In summary, our findings confirmed that higher CG levels in pregnancy possibly played a role in GDM development partly by impairing the functions of insulin, such those involved in as glucose uptake, while promoting inflammation in adipocyte.

TNFα dynamics during the oral glucose tolerance test vary according to the level of insulin resistance in pregnant women

INTRODUCTION

TNFα is suspected to play a role in inflammation and insulin resistance leading to higher risk of metabolic impairment. Controversies exist concerning the role of TNFα in gestational insulin resistance. We investigated the interrelations between TNFα and insulin resistance in a large population-based cohort of pregnant women.

METHODS

Women (n = 756) were followed prospectively at 5-16 weeks and 24-28 weeks of pregnancy. Anthropometric measures and blood samples were collected at both visits. A 75-g oral glucose tolerance test (OGTT) was conducted at the second trimester to assess insulin sensitivity status (homeostasis model of assessment of insulin resistance and Matsuda index). TNFα was measured at the first trimester (nonfasting) and at each time point of the OGTT.

RESULTS

Participants were 28.4 ± 4.4 years old and had a mean body mass index of 25.5 ± 5.5 kg/m(2) at first trimester. Median TNFα levels were 1.56 (interquartile range, 1.18-2.06) pg/mL at first trimester and 1.61 (interquartile range, 1.12-2.13) pg/mL at second trimester (1 h after glucose load). At second trimester, higher TNFα levels were associated with higher insulin resistance index levels (r = 0.37 and -0.30 for homeostasis model of assessment of insulin resistance and Matsuda index, respectively; P < .0001), even after adjustment for age, body mass index, triglycerides, and adiponectin. Women with higher insulin resistance showed a continuing decrease in TNFα levels during the OGTT, whereas women who were more insulin sensitive showed an increase in TNFα at hour 1 and a decrease at hour 2 of the test.

CONCLUSION

Higher insulin resistance is associated with higher levels of circulating TNFα at first and second trimesters of pregnancy. TNFα level dynamics during an OGTT at second trimester vary according to insulin-resistance state.

Pregnancy in obese mice protects selectively against visceral adiposity and is associated with increased adipocyte estrogen signalling

Maternal obesity is linked with increased adverse pregnancy outcomes for both mother and child. The metabolic impact of excessive fat within the context of pregnancy is not fully understood. We used a mouse model of high fat (HF) feeding to induce maternal obesity to identify adipose tissue-mediated mechanisms driving metabolic dysfunction in pregnant and non-pregnant obese mice. As expected, chronic HF-feeding for 12 weeks preceding pregnancy increased peripheral (subcutaneous) and visceral (mesenteric) fat mass. However, unexpectedly at late gestation (E18.5) HF-fed mice exhibited a remarkable normalization of visceral but not peripheral adiposity, with a 53% reduction in non-pregnant visceral fat mass expressed as a proportion of body weight (P<0.001). In contrast, in control animals, pregnancy had no effect on visceral fat mass proportion. Obesity exaggerated glucose intolerance at mid-pregnancy (E14.5). However by E18.5, there were no differences, in glucose tolerance between obese and control mice. Transcriptomic analysis of visceral fat from HF-fed dams at E18.5 revealed reduced expression of genes involved in de novo lipogenesis (diacylglycerol O-acyltransferase 2 - Dgat2) and inflammation (chemokine C-C motif ligand 2 - Ccl2) and upregulation of estrogen receptor α (ERα) compared to HF non pregnant. Attenuation of adipose inflammation was functionally confirmed by a 45% reduction of CD11b⁺CD11c⁺ adipose tissue macrophages (expressed as a proportion of all stromal vascular fraction cells) in HF pregnant compared to HF non pregnant animals (P<0.001). An ERα selective agonist suppressed both de novo lipogenesis and expression of lipogenic genes in adipocytes in vitro. These data show that, in a HF model of maternal obesity, late gestation is associated with amelioration of visceral fat hypertrophy, inflammation and glucose intolerance, and suggest that these effects are mediated in part by elevated visceral adipocyte ERα signaling.

Supplementation with conjugated linoleic acids extends the adiponectin deficit during early lactation in dairy cows

Decreasing insulin sensitivity (IS) in peripheral tissues allows for partitioning nutrients towards the mammary gland. In dairy cows, extensive lipid mobilization and continued insulin resistance (IR) are typical for early lactation. Adiponectin, an adipokine, promotes IS. Supplementation with conjugated linoleic acids (CLA) in rodents and humans reduces fat mass whereby IR and hyperinsulinemia may occur. In dairy cows, CLA reduce milk fat, whereas body fat, serum free fatty acids and leptin are not affected. We aimed to investigate the effects of CLA supplementation on serum and adipose tissue (AT) adiponectin concentrations in dairy cows during the lactation driven and parity modulated changes of metabolism. High yielding cows (n=33) were allocated on day 1 post partum to either 100 g/day of a CLA mixture or a control fat supplement (CON) until day 182 post partum. Blood and subcutaneous (sc) AT (AT) biopsy samples were collected until day 252 post partum to measure adiponectin. Serum adiponectin decreased from day 21 pre partum reaching a nadir at calving and thereafter increased gradually. The distribution of adiponectin molecular weight forms was neither affected by time, parity nor treatment. Cows receiving CLA had decreased serum adiponectin concentrations whereby primiparous cows responded about 4 weeks earlier than multiparous cows. The time course of adiponectin concentrations in sc AT (corrected for residual blood) was similar to serum concentrations, without differences between CLA and CON. CLA supplementation attenuated the post partum increase of circulating adiponectin thus acting towards prolongation of peripartal IR and drain of nutrients towards the mammary gland.

Management of reproduction and pregnancy complications in maternal obesity: which role for dietary polyphenols?

Obesity is a global and dramatic public health problem; maternal obesity represents one of the main risk factors of infertility and pregnancy complications as it is associated with adverse maternal and offspring outcomes. In the last few years, adipose tissue dysfunction associated with altered adipocytokine secretion has been suggested to play a critical role in all the phases of reproductive process. Obesity is a nutrition-related disorder. In this regard, dietary intervention strategies, such as high intake of fruit and vegetables, have shown significant effects in both preserving health and counteracting obesity-associated diseases. Evidence has been provided that polyphenols, important constituents of plant-derived food, can influence developmental program of oocyte and embryo, as well as pregnancy progression by modulating several cellular pathways. This review will examine the controversial results so far obtained on adipocytokine involvement in fertility impairment and pregnancy complications. Furthermore, the different effects exerted by polyphenols on oocyte, embryo, and pregnancy development will be also taken in account.

Macrophage infiltration and stress-signaling in omental and subcutaneous adipose tissue in diabetic pregnancies

OBJECTIVE

To examine if, as in obesity, pregnancies complicated by gestational diabetes mellitus (GDM) exhibit increased macrophage infiltration and activated MAP-kinases in omental adipose tissue.

METHODS

Paired omental (OM) and abdominal subcutaneous (SC) fat samples were collected from 11 GDM and 20 normal pregnancies during cesarean delivery. Tissues were stained to detect macrophages, and analyzed to assess MAP-kinases.

RESULTS

OM had higher macrophage counts than SC in GDM (6.10 ± 2.20 versus 2.53 ± 1.45, p = 0.04), but not in normal pregnancies (p = 0.346). GDM pregnancies had more macrophages than normal pregnancies in OM (6.10 ± 2.20 versus 1.29 ± 0.55, p = 0.01), while only a trend was observed in SC fat (p = 0.08). Significant correlation (R = 0.619, p = 0.005) was observed between OM-macrophage infiltration and insulin resistance. Using multivariate analysis, only obesity independently associated with GDM. Expression of total p38MAP-kinase was higher in OM versus SC in both normal and GDM pregnancies, without significant differences between these groups. However, expression of activated p-p38MAP-kinase, and its upstream kinase MKK4, was comparable between fat depots.

CONCLUSION

GDM pregnancies demonstrate increased macrophage infiltration to OM fat, correlating with higher insulin resistance. As in non-pregnant-patients obesity and OM macrophage infiltration may be on the same causal pathway, leading to GDM. Yet, this occurs without activation of p38MAP-kinase signaling.

Nutritional programming of insulin resistance: causes and consequences

Strong evidence indicates that adverse prenatal and early postnatal environments have a significant long-term influence on risk factors that result in insulin resistance, type 2 diabetes (T2D), and cardiovascular disease later in life. Here we discuss current knowledge of how maternal and neonatal nutrition influence early growth and the long-term risk of developing insulin resistance in different organs and at the whole-body level. Accumulating evidence supports a role for epigenetic mechanisms underlying this nutritional programming, consisting of heritable changes that regulate gene expression which in turn shapes the phenotype across generations. Deciphering these molecular mechanisms in key tissues and discovering key biological markers may provide valuable insight towards the development of effective intervention strategies.

Tumor necrosis factor-induced cerebral insulin resistance in Alzheimer's disease links numerous treatment rationales

The evident limitations of the amyloid theory of the pathogenesis of Alzheimer's disease are increasingly putting alternatives in the spotlight. We argue here that a number of independently developing approaches to therapy-including specific and nonspecific anti-tumor necrosis factor (TNF) agents, apolipoprotein E mimetics, leptin, intranasal insulin, the glucagon-like peptide-1 mimetics and glycogen synthase kinase-3 (GSK-3) antagonists-are all part of an interlocking chain of events. All these approaches inform us that inflammation and thence cerebral insulin resistance constitute the pathway on which to focus for a successful clinical outcome in treating this disease. The key link in this chain presently absent is a recognition by Alzheimer's research community of the long-neglected history of TNF induction of insulin resistance. When this is incorporated into the bigger picture, it becomes evident that the interventions we discuss are not competing alternatives but equally valid approaches to correcting different parts of the same pathway to Alzheimer's disease. These treatments can be expected to be at least additive, and conceivably synergistic, in effect. Thus the inflammation, insulin resistance, GSK-3, and mitochondrial dysfunction hypotheses are not opposing ideas but stages of the same fundamental, overarching, pathway of Alzheimer's disease pathogenesis. The insight this provides into progenitor cells, including those involved in adult neurogenesis, is a key part of this approach. This pathway also has therapeutic implications for other circumstances in which brain TNF is pathologically increased, such as stroke, traumatic brain injury, and the infectious disease encephalopathies.

Adipokines, an adipose tissue and placental product with biological functions during pregnancy

Latter half of pregnancy is characterized by a "physiological diabetogenic state" since changes in insulin-sensitivity have been well documented. These changes ensure continuous supply of nutrients to the growing fetus. In the last years the role of adipocyte-derived signaling molecules, collectively known as adipokines has been object of different in vitro and in vivo studies. Of interest, adipokines and/or their receptors are expressed in the placental tissue which, therefore, can contribute to development of maternal insulin-resistance and, as a consequence, fetal growth. Leptin, adiponectin, and resistin represent the most well studied adipokines and, with the exception of adiponectin, their serum and placental levels increase as pregnancy progresses. High levels of adipokines have also been detected in umbilical plasma hence suggesting a possible role on fetal development and metabolism; however, it remains still unclear if such adipokines can directly stimulate fetal tissues development acting as growth factors. In addition to their well known metabolic effects, we also reported studies describing the role of adipokines in promoting proliferation and invasiveness of trophoblast cells and affecting local angiogenic processes. These observations strongly suggest that adipokines, by alternatively interfering with placental development, may affect pregnancy outcome and fetal growth. However, further studies are needed to better understand the local regulation of their expression. © 2012 International Union of Biochemistry and Molecular Biology, Inc.