Deletion of inducible nitric-oxide synthase in leptin-deficient mice improves brown adipose tissue function

Abstract Background: Leptin and nitric oxide (NO) on their own participate in the control of non-shivering thermogenesis. However, the functional interplay between both factors in this process has not been explored so far. Therefore, the aim of the present study was to analyze the impact of the absence of the inducible NO synthase (iNOS) gene in the regulation of energy balance in ob/ob mice. Methods and Findings: Double knockout (DBKO) mice simultaneously lacking the ob and iNOS genes were generated, and the expression of molecules involved in the control of brown fat cell function was analyzed by real-time PCR, western-blot and immunohistochemistry. Twelve week-old DBKO mice exhibited reduced body weight (p,0.05), decreased amounts of total fat pads (p,0.05), lower food efficiency rates (p,0.05) and higher rectal temperature (p,0.05) than ob/ob mice. Ablation of iNOS also improved the carbohydrate and lipid metabolism of ob/ob mice. DBKO showed a marked reduction in the size of brown adipocytes compared to ob/ob mutants. In this sense, in comparison to ob/ob mice, DBKO rodents showed an increase in the expression of PR domain containing 16 (Prdm16), a transcriptional regulator of brown adipogenesis. Moreover, iNOS deletion enhanced the expression of mitochondria-related proteins, such as peroxisome proliferatoractivated receptor c coactivator-1 a (Pgc-1a), sirtuin-1 (Sirt-1) and sirtuin-3 (Sirt-3). Accordingly, mitochondrial uncoupling proteins 1 and 3 (Ucp-1 and Ucp-3) were upregulated in brown adipose tissue (BAT) of DBKO mice as compared to ob/ob rodents. Conclusion: Ablation of iNOS improved the energy balance of ob/ob mice by decreasing food efficiency through an increase in thermogenesis. These effects may be mediated, in part, through the recovery of the BAT phenotype and brown fat cell function improvement

A Fermented Food Product Containing Lactic Acid Bacteria Protects ZDF Rats from the Development of Type 2 Diabetes

Type 2 diabetes (T2D) is a complex metabolic disease, which involves a maintained hyperglycemia due to the development of an insulin resistance process. Among multiple risk factors, host intestinal microbiota has received increasing attention in T2D etiology and progression. In the present study, we have explored the effect of long-term supplementation with a non-dairy fermented food product (FFP) in Zucker Diabetic and Fatty (ZDF) rats T2D model. The supplementation with FFP induced an improvement in glucose homeostasis according to the results obtained from fasting blood glucose levels, glucose tolerance test, and pancreatic function. Importantly, a significantly reduced intestinal glucose absorption was found in the FFP-treated rats. Supplemented animals also showed a greater survival suggesting a better health status as a result of the FFP intake. Some dissimilarities have been observed in the gut microbiota population between control and FFP-treated rats, and interestingly a tendency for better cardiometabolic markers values was appreciated in this group. However, no significant differences were observed in body weight, body composition, or food intake between groups. These findings suggest that FFP induced gut microbiota modifications in ZDF rats that improved glucose metabolism and protected from T2D development

Changes in brown adipose tissue lipid mediator signatures with aging, obesity, and DHA supplementation in female mice

Brown adipose tissue (BAT) dysfunction in aging and obesity has been related to chronic unresolved inflammation, which could be mediated by an impaired production of specialized proresolving lipid mediators (SPMs), such as Lipoxins-LXs, Resolvins-Rvs, Protectins-PDs, and Maresins-MaRs. Our aim was to characterize the changes in BAT SPMs signatures and their association with BAT dysfunction during aging, especially under obesogenic conditions, and their modulation by a docosahexaenoic acid (DHA)-rich diet. Lipidomic, functional, and molecular studies were performed in BAT of 2-and 18-month- old lean (CT) female mice and in 18-month- old diet-induced obese (DIO) mice fed with a high-fat diet (HFD), or a DHA-enriched HFD. Aging downregulated Prdm16 and UCP1 levels, especially in DIO mice, while DHA partially restored them. Arachidonic acid (AA)-derived LXs and DHA-derived MaRs and PDs were the most abundant SPMs in BAT of young CT mice.Interestingly, the sum of LXs and of PDs were significantly lower in aged DIO mice compared to young CT mice. Some of the SPMs most significantly reduced in obese-aged mice included LXB4, MaR2, 4S,14S-diHDHA, 10S,17S-diHDHA (a.k.a. PDX), and RvD6. In contrast, DHA increased DHA-derived SPMs, without modifying LXs. However, MicroPET studies showed that DHA was not able to counteract the impaired cold exposure response in BAT of obese-aged mice. Our data suggest that a defective SPMs production could underlie the decrease of BAT activity observed in obese-aged mice, and highlight the relevance to further characterize the physiological role and therapeutic potential of specific SPMs on BAT development and function

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Leptin administration favors muscle mass accretion by decreasing FoxO3a and increasing PGC-1alpha in ob/ob mice

Absence of leptin has been associated with reduced skeletal muscle mass in leptin-deficient ob/ob mice. The aim of our study was to examine the effect of leptin on the catabolic and anabolic pathways regulating muscle mass. Gastrocnemius, extensor digitorum longus and soleus muscle mass as well as fiber size were significantly lower in ob/ob mice compared to wild type littermates, being significantly increased by leptin administration (P<0.001). This effect was associated with an inactivation of the muscle atrophy-related transcription factor forkhead box class O3 (FoxO3a) (P<0.05), and with a decrease in the protein expression levels of the E3 ubiquitin-ligases muscle atrophy F-box (MAFbx) (P<0.05) and muscle RING finger 1 (MuRF1) (P<0.05). Moreover, leptin increased (P<0.01) protein expression levels of peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha), a regulator of muscle fiber type, and decreased (P<0.05) myostatin protein, a negative regulator of muscle growth. Leptin administration also activated (P<0.01) the regulators of cell cycle progression proliferating cell nuclear antigen (PCNA) and cyclin D1, and increased (P<0.01) myofibrillar protein troponin T. The present study provides evidence that leptin treatment may increase muscle mass of ob/ob mice by inhibiting myofibrillar protein degradation as well as enhancing muscle cell proliferation

Effects of Maresin 1 (MaR1) on Colonic Inflammation and Gut Dysbiosis in Diet-Induced Obese Mice

The aim of this study was to characterize the effects of Maresin 1 (MaR1), a DHA-derived pro-resolving lipid mediator, on obesity-related colonic inflammation and gut dysbiosis in diet-induced obese (DIO) mice. In colonic mucosa of DIO mice, the MaR1 treatment decreased the expression of inflammatory genes, such as Tnf-α and Il-1β. As expected, the DIO mice exhibited significant changes in gut microbiota composition at the phylum, genus, and species levels, with a trend to a higher Firmicutes/Bacteroidetes ratio. Deferribacteres and Synergistetes also increased in the DIO animals. In contrast, these animals exhibited a significant decrease in the content of Cyanobacteria and Actinobacteria. Treatment with MaR1 was not able to reverse the dysbiosis caused by obesity on the most abundant phyla. However, the MaR1 treatment increased the content of P. xylanivorans, which have been considered to be a promising probiotic with healthy effects on gut inflammation. Finally, a positive association was found between the Deferribacteres and Il-1β expression, suggesting that the increase in Deferribacteres observed in obesity could contribute to the overexpression of inflammatory cytokines in the colonic mucosa. In conclusion, MaR1 administration ameliorates the inflammatory state in the colonic mucosa and partially compensates changes on gut microbiota caused by obesity

Effects of Maresin 1 (MaR1) on Colonic Inflammation and Gut Dysbiosis in Diet-Induced Obese Mice

The aim of this study was to characterize the effects of Maresin 1 (MaR1), a DHA-derived pro-resolving lipid mediator, on obesity-related colonic inflammation and gut dysbiosis in diet-induced obese (DIO) mice. In colonic mucosa of DIO mice, the MaR1 treatment decreased the expression of inflammatory genes, such as Tnf-α and Il-1β. As expected, the DIO mice exhibited significant changes in gut microbiota composition at the phylum, genus, and species levels, with a trend to a higher Firmicutes/Bacteroidetes ratio. Deferribacteres and Synergistetes also increased in the DIO animals. In contrast, these animals exhibited a significant decrease in the content of Cyanobacteria and Actinobacteria. Treatment with MaR1 was not able to reverse the dysbiosis caused by obesity on the most abundant phyla. However, the MaR1 treatment increased the content of P. xylanivorans, which have been considered to be a promising probiotic with healthy effects on gut inflammation. Finally, a positive association was found between the Deferribacteres and Il-1β expression, suggesting that the increase in Deferribacteres observed in obesity could contribute to the overexpression of inflammatory cytokines in the colonic mucosa. In conclusion, MaR1 administration ameliorates the inflammatory state in the colonic mucosa and partially compensates changes on gut microbiota caused by obesity

Intestinal permeability, gut inflammation, and gut immune system response are linked to aging-related changes in gut microbiota composition: A study in female mice

Aging entails changes at the cellular level that increase the risk of various pathologies. An association between gut microbiota and age-related diseases has also been attributed. This study aims to analyze changes in fecal microbiota composition and their association with genes related to immune response, gut inflammation, and intestinal barrier impairment. Fecal samples of female mice at different ages (2 months, 6 months, 12 months, and 18 months) and gene expression in colon tissue were analyzed. Results showed that the older mice group had a more diverse microbiota than the younger group. Additionally, the abundance of Cyanobacteria, Proteobacteria, Flavobacteriaceae, Bacteroides, Parabacteroides, Prevotellaceae_UCG-001, Akkermansia, and Parabacteroides goldsteinii increased with age. In contrast, there was a notable decline in Clostridiaceae, Lactobacillaceae, Monoglobaceae, Ligilactobacillus, Limosilactobacillus, Mucispirillum, and Bacteroides faecichinchillae. These bacteria imbalances were positively correlated with increased inflammation markers in the colon, including Tnf-α, Ccl2, and Ccl12, and negatively with the expression of tight junction genes (Jam2, Tjp1, and Tjp2), as well as immune response genes (Cd4, Cd72, Tlr7, Tlr12, and Lbp). In conclusion, high levels of diversity did not result in improved health in older mice; however, the imbalance in bacteria abundance that occurs with aging might contribute to immune senescence, inflammation, and leaky gut disease

The inhibitory effect of leptin on angiotensin II-induced vasoconstriction is blunted in spontaneously hypertensive rats

OBJECTIVE: Leptin attenuates the angiotensin II-induced increase of cytosolic calcium ([Ca2+]i) and vasoconstriction in the aorta of normotensive Wistar rats. To determine whether these effects may be altered in hypertension, we assessed the effect of leptin on angiotensin II-induced vascular response in the aorta of 10-week-old spontaneously hypertensive rats (SHR). METHODS: Contractile responses to angiotensin II (100 nmol/l) in the presence of different concentrations of leptin (0.1, 1, 10, 100 nmol/l) were evaluated in isolated aortic rings by the organ bath system. [Ca2+]i was measured in vascular smooth muscle cells (VSMCs) using Fura-2 fluorescence. The expression of the short (OB-Ra) and long (OB-Rb) isoforms of the leptin receptor in VSMCs was evaluated by real-time reverse transcriptase-polymerase chain reaction and western-blot analysis. RESULTS: Circulating leptin concentrations were increased in SHR. Serum metabolic parameters, including glucose, insulin, total cholesterol and triglyceride levels, were also elevated in SHR. Leptin did not modify the angiotensin II-induced vasoconstriction in SHR either in intact or endothelium-denuded aortic rings. In addition, leptin was not able either to diminish the angiotensin II-induced the peak rise of [Ca2+]i or to accelerate the recovery rate to basal calcium levels in VSMCs from SHR. However, OB-Ra and OB-Rb mRNA and protein expression were increased in SHR VSMCs. CONCLUSIONS: The lack of effect of leptin on angiotensin II-induced contraction in the aorta of SHR is due to an impaired handling of [Ca2+]i in VSMCs. Hyperleptinemia and overexpression of OB-R in VSMCs could be compensatory mechanisms against VSMC leptin resistance in genetically hypertensive rats

The inhibitory effect of leptin on angiotensin II-induced vasoconstriction is blunted in spontaneously hypertensive rats

OBJECTIVE: Leptin attenuates the angiotensin II-induced increase of cytosolic calcium ([Ca2+]i) and vasoconstriction in the aorta of normotensive Wistar rats. To determine whether these effects may be altered in hypertension, we assessed the effect of leptin on angiotensin II-induced vascular response in the aorta of 10-week-old spontaneously hypertensive rats (SHR). METHODS: Contractile responses to angiotensin II (100 nmol/l) in the presence of different concentrations of leptin (0.1, 1, 10, 100 nmol/l) were evaluated in isolated aortic rings by the organ bath system. [Ca2+]i was measured in vascular smooth muscle cells (VSMCs) using Fura-2 fluorescence. The expression of the short (OB-Ra) and long (OB-Rb) isoforms of the leptin receptor in VSMCs was evaluated by real-time reverse transcriptase-polymerase chain reaction and western-blot analysis. RESULTS: Circulating leptin concentrations were increased in SHR. Serum metabolic parameters, including glucose, insulin, total cholesterol and triglyceride levels, were also elevated in SHR. Leptin did not modify the angiotensin II-induced vasoconstriction in SHR either in intact or endothelium-denuded aortic rings. In addition, leptin was not able either to diminish the angiotensin II-induced the peak rise of [Ca2+]i or to accelerate the recovery rate to basal calcium levels in VSMCs from SHR. However, OB-Ra and OB-Rb mRNA and protein expression were increased in SHR VSMCs. CONCLUSIONS: The lack of effect of leptin on angiotensin II-induced contraction in the aorta of SHR is due to an impaired handling of [Ca2+]i in VSMCs. Hyperleptinemia and overexpression of OB-R in VSMCs could be compensatory mechanisms against VSMC leptin resistance in genetically hypertensive rats