Epigenetic Mechanisms of Transmission of Metabolic Disease across Generations.

Both human and animal studies indicate that environmental exposures experienced during early life can robustly influence risk for adult disease. Moreover, environmental exposures experienced by parents during either intrauterine or postnatal life can also influence the health of their offspring, thus initiating a cycle of disease risk across generations. In this Perspective, we focus on epigenetic mechanisms in germ cells, including DNA methylation, histone modification, and non-coding RNAs, which collectively may provide a non-genetic molecular legacy of prior environmental exposures and influence transcriptional regulation, developmental trajectories, and adult disease risk in offspring.

Kinin B1 receptor gene ablation affects hypothalamic CART productionb.

A role for the kinin B1 receptor in energy-homeostatic processes was implicated in previous studies; notably, the studies where kinin B1 receptor knockout mice (B1-/-) were shown to have impaired adiposity, impaired leptin and insulin production, lower feed efficiency, protection from liver steatosis and diet-induced obesity when fed a high fat diet (HFD). In particular, in a model where the B1 receptor is expressed exclusively in the adipose tissue, it rescues the plasma insulin concentration and the weight gain seen in wild type mice. Taking into consideration that leptin participates in the formation of hypothalamic nuclei, which modulate energy expenditure, and feeding behavior, we hypothesized that these brain regions could also be altered in B1-/- mice. We observed for the first time a difference in the gene expression pattern of cocaine and amphetamine related transcript (CART) in the (lateral hypothalamic area (LHA) resulting from the deletion of the kinin B1 receptor gene. The correlation between CART expression in the LHA and the thwarting of diet-induced obesity corroborates independent correlations between CART and obesity. Furthermore, it seems to indicate that the mechanism underlying the 'lean' phenotype of B1-/- mice does not stem solely from changes in peripheral tissues but may also receive contributions from changes in the hypothalamic machinery involved in energy homeostasis processes.

Increased bone loss and amount of osteoclasts in kinin B1 receptor knockout mice.

AIM: The pathophysiology of periodontal diseases involves aspects of immunity and bone remodelling. Considering the role of the kinin B1 receptor (Bdkrb1) in inflammation and healing, the purpose of this study was to evaluate the contribution of Bdkrb1 to the pathogenesis of periodontitis. MATERIAL AND METHODS: We used a model of ligature-induced experimental periodontitis (LIEP) in mice lacking Bdkrb1 (Bdkrb1(-/-) ) to test the role of this receptor in bone loss and cytokine secretion by lymph nodes cells. Angiotensin-converting enzyme inhibitor (ACEi) was used as a pharmacological strategy to support the genetic model. Also, autonomous effect of Bdkrb1 deletion was evaluated in osteoclasts precursors from bone marrow. RESULTS: Bdkrb1(-/-) mice exhibit increased bone loss and IL-17 secretion in response to LIEP when compared to wild type. LIEP does not modify TNF-α, IFN-γ and IL-10 levels in Bdkrb1(-/-) mice after 21 days. Bone marrow cells from Bdkrb1(-/-) displayed increased differentiation into functional osteoclasts with consistent artificial calcium phosphate degradation. Furthermore, treatment of mice with ACEi prevented bone destruction. CONCLUSION: Bdkrb1 participates in the pathogenesis of LIEP bone loss possibly through mechanisms that involve modulation of the TH 17 response, thereby demonstrating its role in the development of periodontitis.

Lack of kinin B1 receptor potentiates leptin action in the liver.

Kinins B1 and B2 receptors (B1R and B2R) are classically associated with inflammation, but our group has recently demonstrated new roles for B1R in metabolism using a knockout model (B1 (-/-)). B1 (-/-) mice display improvement on leptin and insulin sensitivity and is protected from high fat diet (HFD)-induced obesity. Here, we evaluate the hepatic effects of the B1R ablation and its role on hepatic function. Despite no expression of hepatic B1R, HFD-induced hepatic lipid accumulation was lower than in control animals. B1 (-/-) mice also presented lower hepatic lipogenesis and SCD1 protein content in the liver. When stimulated with exogenous leptin, B1 (-/-) mice exhibited increased hepatic pJAK2. Similarly, leptin signaling was enhanced in the liver of ob/ob-B1 (-/-) mice, as demonstrated by increased levels of pSTAT3 compared to ob/ob. Plasma concentrations of intercellular adhesion molecule 1, fetuin A, leukemia inhibitory factor, tissue inhibitor of metalloprotease-1, resistin, and oncostatin M were reduced in B1 (-/-). Finally, B1 (-/-) mice have increased gene expression of hepatic B2 receptor, but no difference in leptin receptor expression. Our results show that B1 (-/-) mice are protected from non-alcoholic fatty liver disease (NAFLD) after HFD treatment. Since B1R expression was not observed in the liver after HFD, we propose that the cross talk between the adipose tissue and the liver, mainly through leptin, is an important factor contributing to the observed results. Besides that, several other inflammatory mediators already correlated with NAFLD or liver function were found to be altered in our model. Taken together, our data suggest that B1R plays an important role in hepatic steatosis development.

Kinin B1 receptor in adipocytes regulates glucose tolerance and predisposition to obesity.

BACKGROUND: Kinins participate in the pathophysiology of obesity and type 2 diabetes by mechanisms which are not fully understood. Kinin B(1) receptor knockout mice (B(1) (-/-)) are leaner and exhibit improved insulin sensitivity. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that kinin B(1) receptors in adipocytes play a role in controlling whole body insulin action and glucose homeostasis. Adipocytes isolated from mouse white adipose tissue (WAT) constitutively express kinin B(1) receptors. In these cells, treatment with the B(1) receptor agonist des-Arg(9)-bradykinin improved insulin signaling, GLUT4 translocation, and glucose uptake. Adipocytes from B(1) (-/-) mice showed reduced GLUT4 expression and impaired glucose uptake at both basal and insulin-stimulated states. To investigate the consequences of these phenomena to whole body metabolism, we generated mice where the expression of the kinin B(1) receptor was limited to cells of the adipose tissue (aP2-B(1)/B(1) (-/-)). Similarly to B(1) (-/-) mice, aP2-B(1)/B(1) (-/-) mice were leaner than wild type controls. However, exclusive expression of the kinin B(1) receptor in adipose tissue completely rescued the improved systemic insulin sensitivity phenotype of B(1) (-/-) mice. Adipose tissue gene expression analysis also revealed that genes involved in insulin signaling were significantly affected by the presence of the kinin B(1) receptor in adipose tissue. In agreement, GLUT4 expression and glucose uptake were increased in fat tissue of aP2-B(1)/B(1) (-/-) when compared to B(1) (-/-) mice. When subjected to high fat diet, aP2-B(1)/B(1) (-/-) mice gained more weight than B(1) (-/-) littermates, becoming as obese as the wild types. CONCLUSIONS/SIGNIFICANCE: Thus, kinin B(1) receptor participates in the modulation of insulin action in adipocytes, contributing to systemic insulin sensitivity and predisposition to obesity.