Fructose-Rich Diet Affects Mitochondrial DNA Damage and Repair in Rats

Implications of chronic moderate protein-deficiency malnutrition on doxorubicin pharmacokinetics and cardiotoxicity in early post-weaning stage

BACKGROUND

Malnutrition is a common problem in developing countries, and the impact of severe malnutrition on optimal treatment outcomes of chemotherapy in pediatric cancer patients is well documented. However, despite being a more prevalent and distinct entity, moderate malnutrition is until now unexplored for its effects on treatment outcomes.

AIMS

In this study we aimed to investigate the molecular basis of altered pharmacokinetics and cardiotoxicity of doxorubicin observed in early-life chronic moderate protein deficiency malnutrition.

MATERIALS AND METHODS

We developed an animal model of early-life moderate protein-deficiency malnutrition and validated it using clinical samples. This model was used to study pharmacokinetic and toxicity changes and was further utilized to study the molecular changes in liver and heart to get mechanistic insights.

KEY FINDINGS

Here we show that moderate protein-deficiency malnutrition in weanling rats causes changes in drug disposition in the liver by modification of hepatic ABCC3 and MRP2 transporters through the TNFα signalling axis. Furthermore, malnourished rats in repeat-dose doxorubicin toxicity study showed higher toxicity and mortality. A higher accumulation of doxorubicin in the heart was observed which was associated with alterations in cardiac metabolic pathways and increased cardiotoxicity.

SIGNIFICANCE

Our findings indicate that moderate malnutrition causes increased susceptibility towards toxic side effects of chemotherapy. These results may necessitate further investigations and new guidelines on the dosing of chemotherapy in moderately malnourished pediatric cancer patients.

Safety assessment of high fructose corn syrup and fructose used as sweeteners in foods

High Fructose Corn Syrup (HFCS) and Fructose (FR) are widely used sweeteners in many foods and beverages. This study aimed at investigating the cytotoxic effects of HFCS (5%-30%) and FR (62.5-2000 μg/mL) using MTT assay in Human Hepatocellular Carcinoma (HepG2) cells, and genotoxic effects of using Chromosome Aberrations (CAs), Sister Chromatid Exchanges (SCEs), Micronuclei (MN) and comet assays in human lymphocytes. HFCS significantly reduced the cell viability in HepG2 cells at between 7.5% and 30% for 24 and 48 h. 30% HFCS caused a very significant toxic effect. FR had a cytotoxic effect in HepG2 cells at all treatments. However, as fructose concentration decreased, the cell viability decreased. HFCS (10%-20%) and FR (250-2000 μg/mL) decreased the mitotic index at higher concentrations. IC50 value was found to be a 15% for 48 h. IC50 value of FR was detected as 62.5 μg/mL for 24 h and 48 h. HFCS significantly increased CAs frequency at 15% and 20%. FR significantly increased the frequency of CAs at 250, 1000, and 2000 μg/mL for 48 h. Both sweeteners increased the frequency of SCEs at all concentrations. HFCS (15% and 20%) and FR (250, 1000, and 2000 μg/mL) induced MN frequency at higher concentrations. HFCS caused DNA damage in comet assay at 10% -30%. FR increased tail intensity and moment at 125-2000 μg/mL and tail length at 62.5, 250 and 500 μg/mL. Therefore, HFCS and FR are clearly seen to be cytotoxic and genotoxic, especially at higher concentrations.

The Past and Future of Inflammation as a Target to Cancer Prevention

Inflammation is an essential defense mechanism in which innate immune cells are coordinately activated on encounter of harmful stimuli, including pathogens, tissue injury, and toxic compounds and metabolites to neutralize and eliminate the instigator and initiate healing and regeneration. Properly terminated inflammation is vital to health, but uncontrolled runaway inflammation that becomes chronic begets a variety of inflammatory and metabolic diseases and increases cancer risk. Making damaged tissues behave as "wounds that do not heal" and sustaining the production of growth factors whose physiologic function is tissue healing, chronic inflammation accelerates cancer emergence from premalignant lesions. In 1863, Rudolf Virchow, a leading German pathologist, suggested a possible association between inflammation and tumor formation, but it took another 140 years to fully elucidate and appreciate the tumorigenic role of inflammation. Key findings outlined molecular events in the inflammatory cascade that promote cancer onset and progression and enabled a better appreciation of when and where inflammation should be inhibited. These efforts triggered ongoing research work to discover and develop inflammation-reducing chemopreventive strategies for decreasing cancer risk and incidence.

Myosteatosis: Diagnosis, pathophysiology and consequences in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is associated with an increased risk of multisystemic complications, including muscle changes such as sarcopenia and myosteatosis that can reciprocally affect liver function. We conducted a systematic review to highlight innovative assessment tools, pathophysiological mechanisms and metabolic consequences related to myosteatosis in MASLD, based on original articles screened from PUBMED, EMBASE and COCHRANE databases. Forty-six original manuscripts (14 pre-clinical and 32 clinical studies) were included. Microscopy (8/14) and tissue lipid extraction (8/14) are the two main assessment techniques used to measure muscle lipid content in pre-clinical studies. In clinical studies, imaging is the most used assessment tool and included CT (14/32), MRI (12/32) and ultrasound (4/32). Assessed muscles varied across studies but mainly included paravertebral (4/14 in pre-clinical; 13/32 in clinical studies) and lower limb muscles (10/14 in preclinical; 13/32 in clinical studies). Myosteatosis is already highly prevalent in non-cirrhotic stages of MASLD and correlates with disease activity when using muscle density assessed by CT. Numerous pathophysiological mechanisms were found and included: high-fat and high-fructose diet, dysregulation in fatty acid transport and ketogenesis, endocrine disorders and impaired microRNA122 pathway signalling. In this review we also uncover several potential consequences of myosteatosis in MASLD, such as insulin resistance, MASLD progression from steatosis to metabolic steatohepatitis and loss of muscle strength. In conclusion, data on myosteatosis in MASLD are already available. Screening for myosteatosis could be highly relevant in the context of MASLD, considering its correlation with MASLD activity as well as its related consequences.

Dysregulation of mitochondrial dynamics mediated aortic perivascular adipose tissue-associated vascular reactivity impairment under excessive fructose intake

Excessive fructose intake presents the major risk factor for metabolic cardiovascular disease. Perivascular adipose tissue (PVAT) is a metabolic tissue and possesses a paracrine function in regulating aortic reactivity. However, whether and how PVAT alters vascular function under fructose overconsumption remains largely unknown. In this study, male Sprague-Dawley rats (8 weeks old) were fed a 60% high fructose diet (HFD) for 12 weeks. Fasting blood sugar, insulin, and triglycerides were significantly increased by HFD intake. Plasma adiponectin was significantly enhanced in the HFD group. The expression of uncoupling protein 1 (UCP1) and mitochondrial mass were reduced in the aortic PVAT of the HFD group. Concurrently, the expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) and mitochondrial transcription factor A (TFAM) were suppressed. Furthermore, decreased fusion proteins (OPA1, MFN1, and MFN2) were accompanied by increased fission proteins (FIS1 and phospho-DRP1). Notably, the upregulated α-smooth muscle actin (α-SMA) and osteocalcin in the PVAT were concurrent with the impaired reactivity of aortic contraction and relaxation. Coenzyme Q10 (Q, 10 mg/100 mL, 4 weeks) effectively reversed the aforementioned events induced by HFD. Together, these results suggested that the dysregulation of mitochondrial dynamics mediated HFD-triggered PVAT whitening to impair aortic reactivity. Fortunately, coenzyme Q10 treatment reversed HFD-induced PVAT whitening and aortic reactivity.

The Role of High-Fructose Diet in Liver Function of Rodent Models: A Systematic Review of Molecular Analysis

The present systematic review of animal studies on long-term fructose intake in rodents revealed a significant decrease in the activities of antioxidant enzymes due to a fructose-rich diet. The reduced activity of these enzymes led to an increase in oxidative stress, which can cause liver damage in rodents. Of eight studies analyzed, 5 (62.5%) and 1 (12.5%) used male and female rats, respectively, while 2 studies (25%) used female mice. Moreover, half of the studies used HFCS, but the other half employed fructose in the diet. Hence, it is essential to monitor dietary habits to ensure public health and nutrition research outcomes.

Assessing Metabolic Differences Associated with Exposure to Polybrominated Biphenyl and Polychlorinated Biphenyls in the Michigan PBB Registry

BACKGROUND

Polybrominated biphenyls (PBB) and polychlorinated biphenyls (PCB) are persistent organic pollutants with potential endocrine-disrupting effects linked to adverse health outcomes.

OBJECTIVES

In this study, we utilize high-resolution metabolomics (HRM) to identify internal exposure and biological responses underlying PCB and multigenerational PBB exposure for participants enrolled in the Michigan PBB Registry.

METHODS

HRM profiling was conducted on plasma samples collected from 2013 to 2014 from a subset of participants enrolled in the Michigan PBB Registry, including 369 directly exposed individuals (F0) who were alive when PBB mixtures were accidentally introduced into the food chain and 129 participants exposed to PBB in utero or through breastfeeding, if applicable (F1). Metabolome-wide association studies were performed for PBB-153 separately for each generation and Σ PCB (PCB-118, PCB-138, PCB-153, and PCB-180) in the two generations combined, as both had direct PCB exposure. Metabolite and metabolic pathway alterations were evaluated following a well-established untargeted HRM workflow.

RESULTS

Mean levels were 1.75  ng / mL [standard deviation (SD): 13.9] for PBB-153 and 1.04  ng / mL (SD: 0.788) for Σ PCB . Sixty-two and 26 metabolic features were significantly associated with PBB-153 in F0 and F1 [false discovery rate (FDR) p < 0.2 ], respectively. There were 2,861 features associated with Σ PCB (FDR p < 0.2 ). Metabolic pathway enrichment analysis using a bioinformatics tool revealed perturbations associated with Σ PCB in numerous oxidative stress and inflammation pathways (e.g., carnitine shuttle, glycosphingolipid, and vitamin B9 metabolism). Metabolic perturbations associated with PBB-153 in F0 were related to oxidative stress (e.g., pentose phosphate and vitamin C metabolism) and in F1 were related to energy production (e.g., pyrimidine, amino sugars, and lysine metabolism). Using authentic chemical standards, we confirmed the chemical identity of 29 metabolites associated with Σ PCB levels (level 1 evidence).

CONCLUSIONS

Our results demonstrate that serum PBB-153 is associated with alterations in inflammation and oxidative stress-related pathways, which differed when stratified by generation. We also found that Σ PCB was associated with the downregulation of important neurotransmitters, serotonin, and 4-aminobutanoate. These findings provide novel insights for future investigations of molecular mechanisms underlying PBB and PCB exposure on health. https://doi.org/10.1289/EHP12657.

High-fructose corn syrup intake increases hepatic mitochondrial DNA copy number and methylation in adolescent rats

High-fructose corn syrup (HFCS) is consumed worldwide. However, it has been demonstrated that an increased intake of sweetened beverages, including those sweetened using fructose, is associated with the development of childhood obesity. It is unknown why the negative effects of fructose are stronger in young persons than in elderly individuals. In recent years, mitochondria have been identified as 1 of the targets of the negative effects of fructose; they possess their own genome called mitochondrial DNA (mtDNA), which encodes genes involved in metabolic functions. We hypothesized that HFCS intake affects mtDNA in the livers of rats, and that the intensity of these effects is age-dependent. The experimental period was divided into 3 parts: childhood and adolescence (postnatal day [PD] 21-60), young adulthood (PD61-100), and adulthood (PD101-140). Rats in the different age groups were assigned to receive either water (control group [CONT]) or a 20% HFCS solution (HFCS). The hepatic mtDNA copy number of the HFCS group was higher than that of the CONT group in childhood and adolescence. In addition, the mtDNA methylation level was increased in the HFCS group in the same experimental period. No significant differences were observed between the CONT and HFCS groups during the other experimental periods. We demonstrated that HFCS has the strongest effect on mtDNA during childhood and adolescence, suggesting a need to analyze the HFCS intake of young people.

Short-term fructose feeding alters tissue metabolic pathways by modulating microRNAs expression both in young and adult rats

Dietary high fructose (HFrD) is known as a metabolic disruptor contributing to the development of obesity, diabetes, and dyslipidemia. Children are more sensitive to sugar than adults due to the distinct metabolic profile, therefore it is especially relevant to study the metabolic alterations induced by HFrD and the mechanisms underlying such changes in animal models of different ages. Emerging research suggests the fundamental role of epigenetic factors such as microRNAs (miRNAs) in metabolic tissue injury. In this perspective, the aim of the present study was to investigate the involvement of miR-122-5p, miR-34a-5p, and miR-125b-5p examining the effects induced by fructose overconsumption and to evaluate whether a differential miRNA regulation exists between young and adult animals. We used young rats (30 days) and adult rats (90 days) fed on HFrD for a short period (2 weeks) as animal models. The results indicate that both young and adult rats fed on HFrD exhibit an increase in systemic oxidative stress, the establishment of an inflammatory state, and metabolic perturbations involving the relevant miRNAs and their axes. In the skeletal muscle of adult rats, HFrD impair insulin sensitivity and triglyceride accumulation affecting the miR-122-5p/PTP1B/P-IRS-1(Tyr612) axis. In liver and skeletal muscle, HFrD acts on miR-34a-5p/SIRT-1: AMPK pathway resulting in a decrease of fat oxidation and an increase in fat synthesis. In addition, liver and skeletal muscle of young and adult rats exhibit an imbalance in antioxidant enzyme. Finally, HFrD modulates miR-125b-5p expression levels in liver and white adipose tissue determining modifications in de novo lipogenesis. Therefore, miRNA modulation displays a specific tissue trend indicative of a regulatory network that contributes in targeting genes of various pathways, subsequently yielding extensive effects on cell metabolism.

Autophagy and mitochondrial damage in the testis of high-fat diet fed rats

High-fat diet (HFD) affects the physiology of reproduction in males, and many studies have investigated its detrimental effects. In this study, we investigated the cellular response induced by an HFD in the rat testis, focusing on the mitochondrial compartment. After five weeks of HFD, an increase in the levels of malondialdehyde and of reduced form of glutathione in the rat testis indicated an increase in lipid peroxidation. The results showed an increase in autophagy, apoptosis, and mitochondrial damage in the testis of HFD rats. We found a decrease in the protein expression of mitochondrial antioxidant enzymes, such as catalase and SOD2. Immunohistochemical analysis revealed a decrease in the immunofluorescent signal of SOD2, mainly in the spermatogonia and spermatocytes of HFD rats. HFD-induced mitochondrial damage caused a reduction in mitochondria, as evidenced by a decrease in the protein expression of TOM20, a mitochondrial outer membrane receptor. Consistently, HFD enhanced the levels of the PINK1 protein, a mitophagy marker, suggesting the removal of damaged mitochondria under these conditions. Induction of mtDNA damage and repair was stronger in the HFD rat testis. Finally, we found a decrease in the mtDNA copy number and expression of the POLG enzyme, which is involved in mtDNA replication. In conclusion, our results showed that autophagy and apoptosis are activated in the testis of HFD rats as a survival strategy to cope with oxidative stress. Furthermore, HFD-induced oxidative stress affects the mitochondria, inducing mtDNA damage and mtDNA copy number reduction. Mitophagy and mtDNA repair mechanisms might represent a mitochondrial adaptive response.

Jian-Pi-Yi-Shen decoction inhibits mitochondria-dependent granulosa cell apoptosis in a rat model of POF

As a widely applied traditional Chinese medicine (TCM), Jian-Pi-Yi-Shen (JPYS) decoction maybe applied in curing premature ovarian failure (POF) besides chronic kidney disease (CKD). In vivo experiments, 40 female SD (8-week-old) rats were randomized into four groups, namely, control group (negative control), POF model group, JPYS treatment group, and triptorelin treatment group (positive control). JPYS group was treated with JPYS decoction (oral, 11 g/kg) for 60 days, and the triptorelin group was treated with triptorelin (injection, 1.5 mg/kg) for 10 days before the administration of cyclophosphamide (CTX) (50 mg/kg body weight) to establish POF model. We examined apoptosis, mitochondrial function, and target gene (ASK1/JNK pathway and mitochondrial fusion/fission) expression. In vitro experiments, the KGN human granulosa cell line was used. Cells were pretreated with CTX (20, 40, and 60 μg/mL) for 24 h, followed by JPYS-containing serum (2, 4, and 8 %) for 24 h. Thereafter, these cells were employed to assess apoptosis, mitochondrial function, and target gene levels of protein and mRNA. In vivo, JPYS alleviated injury and suppressed apoptosis in POF rats. In addition, JPYS improved ovarian function. JPYS inhibit apoptosis of granulosa cells through improving mitochondrial function by activating ASK1/JNK pathway. In vitro, JPYS inhibited KGN cell apoptosis through inhibited ASK1/JNK pathway and improved mitochondrial function. The effects of GS-49977 were similar to those of JPYS. During POF, mitochondrial dysfunction occurs in the ovary and leads to granulosa cell apoptosis. JPYS decoction improves mitochondrial function and alleviates apoptosis through ASK1/JNK pathway.

Hyperhomocysteinemia exacerbates acute kidney injury via increased mitochondrial damage

Acute kidney injury (AKI) is a complex and common set of multifactorial clinical syndromes, and associated with increased in-hospital mortality. There is increasing evidence that Hyperhomocysteinemia (HHcy) is highly associated with the development of a variety of kidney diseases, including AKI. However, the pathogenesis of HHcy in AKI remains unclear. In this study, we investigated the effect and mechanism of HHcy on cisplatin-induced AKI in mice and NRK-52E cells cultured with HHcy. We confirmed that mice with HHcy had higher serum levels of creatinine and more severe renal tubule injury after cisplatin injection. We found that HHcy aggravated renal mitochondrial damage, mainly manifested as decreased ATP β, significantly increased cytoplasmic Cyt C expression and the ADP/ATP ratio, and a significantly decreased mitochondrial DNA (mtDNA) copy number. In addition, we found that HHcy accelerated cisplatin-induced renal DNA damage; culturing NRK-52E cells with homocysteine (Hcy) could significantly increase apoptosis and mitochondrial damage. Interestingly, we found that Mdivi-1 reduced Hcy-induced mitochondrial damage, thereby reducing the level of apoptosis. In conclusion, these results suggest that HHcy might aggravate the development of AKI by increasing mitochondrial damage and that reducing Hcy levels or inhibiting mitochondrial damage may be a potential therapeutic strategy to delay the development of AKI.

High-fat diet affects autophagy and mitochondrial compartment in rat Harderian gland

The Harderian gland (HG) of Rattus norvegicus is an orbital gland secreting lipids that accumulate in excess under condition of increased lipid metabolism. To study the response elicitated by lipid overload in rat HG, we housed the animals in thermoneutral conditions (28-30°C) in association to high fat diet (HFD). In HFD rats alterated blood lipid levels result in lipid accumulation in HG as demonstrated by the increased gland weight and histochemical/ultrastructural analyses. The HFD-caused oxidative stress forces the gland to trigger antioxidant defense mechanisms and autophagic process, such as lipophagy and mitophagy. Induction of mitochondrial DNA (mtDNA) damage and repair was stronger in HFD-rat HGs. An increase in marker expression levels of mitochondrial biogenesis, fission, and fusion occurred to counteract mtDNA copy number reduction and mitophagy. Therefore, the results demonstrate that rat HG activates autophagy as survival strategy under conditions of increased lipid metabolism and suggest a key role for mitophagy and membrane dynamics in the mitochondrial adaptive response to HFD.

The ameliorative effect of Apium graveolens & curcumin against Non-alcoholic fatty liver disease induced by high fructose-high fat diet in rats

Background

Non-alcoholic fatty liver disease (NAFLD) is a condition resulting from fat aggregates in liver cells and is associated with metabolic syndrome, obesity, and oxidative stress. The present work was designed to investigate the role of celery and curcumin against high-fructose–high-fat (HFHF) diet-induced NAFLD in rats. Thirty male rats were classified into five groups: GP1: control group (rats were fed a normal control diet), GP2: HFHF group as a positive control (rats were fed a HFHF diet) for 20 weeks, GP3: HFHF + sily group, GP4: HFHF + celery group, and GP5: HFHF + cur group (rats in 3, 4, and 5 were treated as in the HFHF group for 16 weeks, then combined treatment daily by gavage for 4 weeks with either silymarin (as a reference drug, 50 mg/kg bw) or celery (300 mg/kg bw) or curcumin (200 mg/kg bw), respectively. The progression of NAFLD was evaluated by estimating tissue serum liver enzymes, glycemic profile, lipid profile, oxidative stress markers in liver tissue, and histopathological examination. Moreover, DNA fragmentation and the released lysosomal enzymes (acid phosphatase, β-galactosidase, and N-acetyl-B-glucosaminidase) were estimated.

Results

Our results showed that HFHF administration for 16 weeks caused liver enzymes elevation, hyperglycemia, and hyperlipidemia. Furthermore, increased hepatic MDA levels along with a decline in GSH levels were observed in the HFHF group as compared to the control group. The results were confirmed by a histopathological study, which showed pathological changes in the HFHF group. DNA fragmentation was also observed, and the lysosomal enzyme activities were increased. On the other hand, oral supplementation of celery and cur improved all these changes compared with positive control groups and HFHF + sily (as a reference drug). Moreover, celery, as well as curcumin co-treatment, reduced HFHF-enhanced DNA fragmentation and inhibited elevated lysosomal enzymes. The celery combined treatment showed the most pronounced ameliorative impact, even more than silymarin did.

Conclusion

Our findings suggest that celery and curcumin consumption may exhibit ameliorative impacts against NALFD progression, while celery showed more ameliorative effect in all parameters.

A possible new activator of PI3K-Huayu Qutan Recipe alleviates mitochondrial apoptosis in obesity rats with acute myocardial infarction

Obesity, which has unknown pathogenesis, can increase the frequency and seriousness of acute myocardial infarction (AMI). This study evaluated effect of Huayu Qutan Recipe (HQR) pretreatment on myocardial apoptosis induced by AMI by regulating mitochondrial function via PI3K/Akt/Bad pathway in rats with obesity. For in vivo experiments, 60 male rats were randomly divided into 6 groups: sham group, AMI group, AMI (obese) group, 4.5, 9.0 and 18.0 g/kg/d HQR groups. The models fed on HQR with different concentrations for 2 weeks before AMI. For in vitro experiments, the cardiomyocytes line (H9c2) was used. Cells were pretreated with palmitic acid (PA) for 24 h, then to build hypoxia model followed by HQR‐containing serum for 24 h. Related indicators were also detected. In vivo, HQR can lessen pathohistological damage and apoptosis after AMI. In addition, HQR improves blood fat levels, cardiac function, inflammatory factor, the balance of oxidation and antioxidation, as well as lessen infarction in rats with obesity after AMI. Meanwhile, HQR can diminish myocardial cell death by improving mitochondrial function via PI3K/Akt/Bad pathway activation. In vitro, HQR inhibited H9c2 cells apoptosis, improved mitochondrial function and activated the PI3K/Akt/Bad pathway, but effects can be peripeteiad by LY294002. Myocardial mitochondrial dysfunction occurs following AMI and can lead to myocardial apoptosis, which can be aggravated by obesity. HQR can relieve myocardial apoptosis by improving mitochondrial function via the PI3K/Akt/Bad pathway in rats with obesity.

Diet, Trimethylamine Metabolism, and Mitochondrial DNA: An Observational Study

SCOPE

Mitochondrial DNA copy number (mtDNAcn) and its methylation level in the D-loop area have been correlated with metabolic health and are suggested to vary in response to environmental stimuli, including diet. Circulating levels of trimethylamine-n-oxide (TMAO), which is an oxidative derivative of the trimethylamine (TMA) produced by the gut microbiome from dietary precursors, have been associated with chronic diseases and are suggested to have an impact on mitochondrial dynamics. This study is aimed to investigate the relationship between diet, TMA, TMAO, and mtDNAcn, as well as DNA methylation.

METHODS AND RESULTS

Two hundred subjects with extreme (healthy and unhealthy) dietary patterns are recruited. Dietary records are collected to assess their nutrient intake and diets' quality (Healthy Eating Index). Blood levels of TMA and TMAO, circulating levels of TMA precursors and their dietary intakes are measured. MtDNAcn, nuclear DNA methylation long interspersed nuclear element 1 (LINE-1), and strand-specific D-loop methylation levels are assessed. There is no association between dietary patterns and mtDNAcn. The TMAO/TMA ratio is negatively correlated with d-loop methylation levels but positively with mtDNAcn.

CONCLUSIONS

These findings suggest a potential association between TMA metabolism and mitochondrial dynamics (and mtDNA), indicating a new avenue for further research.

The therapeutic effects of distinct exercise types on metabolic syndrome-induced reproductive system impairment in male rats: Potential contribution of mitochondria-related genes

A sedentary lifestyle and high fructose dietary habits cause diseases, such as metabolic syndrome (MS). The study was aimed to investigate the potential ameliorative effects of different exercise interventions on high fructose-induced MS-mediated reproductive system disruption of male rats. Rats were divided into four groups (n = 6): Control, MS, MS+aerobic exercise (AE) and MS+anaerobic exercise (ANE). MS was induced by using tap water containing 30% fructose for 8 weeks. After the induction of MS, AE/ANE implementations were started for 6 weeks. Testis tissue and serum samples of rats were stored for biochemical and molecular analyses. Serum total antioxidant status level increased in the MS+AE group compared to all groups. Also, serum total oxidant status level, which increased by MS, decreased with AE, but not altered with ANE. Moreover, MS markedly decreased serum luteinizing hormone, but not changed the follicle-stimulating hormone. However, serum hormone levels were similar to the control group in both MS+AE and MS+ANE groups. MS upregulated mitochondria-related genes' mRNA expressions (MFN2, PGC1A, PPARG, PARP2 and TXNL4B). These increases, except for PPARG, were normalized with both exercise types. These results revealed that mitochondria-related genes may have a crucial role in MS-mediated male reproductive impairment and therapeutic effects of exercises.

Mitochondrial DNA and Epigenetics: Investigating Interactions with the One-Carbon Metabolism in Obesity

Mitochondrial DNA copy number (mtDNAcn) has been proposed for use as a surrogate biomarker of mitochondrial health, and evidence suggests that mtDNA might be methylated. Intermediates of the one-carbon cycle (1CC), which is duplicated in the cytoplasm and mitochondria, have a major role in modulating the impact of diet on the epigenome. Moreover, epigenetic pathways and the redox system are linked by the metabolism of glutathione (GSH). In a cohort of 101 normal-weight and 97 overweight/obese subjects, we evaluated mtDNAcn and methylation levels in both mitochondrial and nuclear areas to test the association of these marks with body weight, metabolic profile, and availability of 1CC intermediates associated with diet. Body composition was associated with 1CC intermediate availability. Reduced levels of GSH were measured in the overweight/obese group (p = 1.3∗10⁻⁵). A high BMI was associated with lower LINE-1 (p = 0.004) and nominally lower methylenetetrahydrofolate reductase (MTHFR) gene methylation (p = 0.047). mtDNAcn was lower in overweight/obese subjects (p = 0.004) and independently correlated with MTHFR methylation levels (p = 0.005) but not to LINE-1 methylation levels (p = 0.086). DNA methylation has been detected in the light strand but not in the heavy strand of the mtDNA. Although mtDNA methylation in the light strand did not differ between overweight/obese and normal-weight subjects, it was nominally correlated with homocysteine levels (p = 0.035) and MTHFR methylation (p = 0.033). This evidence suggests that increased body weight might perturb mitochondrial-nuclear homeostasis affecting the availability of nutrients acting as intermediates of the one-carbon cycle.

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 β-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.

High Sugar-Sweetened Beverage Consumption is Associated with Increased Healthcare Utilization in Inflammatory Bowel Disease: A Multiyear, Prospective Analysis

BACKGROUND

Dietary factors like sugar-sweetened beverage (SSB) consumption are known to impact disease course in a variety of illnesses; however, long-term outcomes are not well documented for inflammatory bowel disease.

OBJECTIVE

Does high consumption of SSBs lead to high healthcare utilization (hospitalizations and emergency department visits), inflammation and disease severity in patients with Inflammatory Bowel Disease?

DESIGN

A prospective cohort study was conducted from 2015-2019. Patients enrolled in the discovery study cohort were followed for 3 years whereas patients in the validation cohort were followed for 2 years. They underwent nutritional assessment and received routine care. Dietary intakes of SSBs and fiber were quantified by a validated, self-reported questionnaire.

PARTICIPANTS/SETTING

For the discovery study cohort, 1133 adult patients were recruited from the University of Pittsburgh Medical Center (UPMC) Digestive Disease Clinic in Pittsburgh, PA. Eligible patients had a pre-existing diagnosis of Crohn's disease (CD) or Ulcerative colitis (UC) and had at least annual follow-up at this tertiary referral center.

EXPOSURE

High SSB consumption was defined as 7 or more SSBs per week. Moderate was defined as greater than 2 but fewer than 7 SSBs per week. Low SSB consumption was defined as 2 or fewer SSBs per week.

MAIN OUTCOME MEASURES

Primary outcome was time to hospitalization and emergency department visits. Secondary outcomes assessed laboratory markers of disease severity and inflammation. Tertiary outcomes assessed time to hospitalization and emergency department visits in a subsequent independent cohort of patients.

STATISTICAL ANALYSIS PERFORMED

Multivariable logistic regression, Kaplan-Meier, Cox proportional hazards modeling RESULTS: The discovery cohort included of 1133 adult IBD patients (female 58%, CD 70%, UC 30%, Median age 46y). Low SSB consumption, moderate SSB consumption, and high SSB consumption occurred in 57%, 17%, and 26% in the discovery cohort respectively. Among patients without active disease at enrollment, high SSB consumption was associated with decreased time to hospitalization and emergency department visits when compared to low SSB consumption (HR 1.55 [1.06 - 2.27]; HR 1.53 [1.10 - 2.13]). In terms of disease severity and inflammatory biomarkers, high SSB consumption was associated with increase odds of elevated erythrocyte sedimentation rate (OR 2.04 [1.31-3.18]), elevated C-reactive protein (OR 1.60 [1.07-2.37]), Eosinophilia (OR 1.88 [1.06-3.335]), and Monocytosis (OR 1.81 [1.18-2.79]) when compared to low SSB consumption after adjusting for baseline differences. Lastly, the validation cohort produced similar results to our primary outcome (high SSB consumption was associated with decreased time to hospitalization and emergency department visits when compared to low SSB consumption).

CONCLUSION

High SSB consumption was associated with decreased time to hospitalization and emergency department visits. Furthermore, high SSB consumption is associated with disease severity biomarkers and inflammation. Prospective studies assessing the therapeutic impact of nutritional counseling and decreased SSB consumption on long-term IBD clinical course are warranted.

Cangfudaotan decoction inhibits mitochondria-dependent apoptosis of granulosa cells in rats with polycystic ovarian syndrome

Polycystic ovary syndrome (PCOS) is a universal endocrine and metabolic disorder prevalent in reproductive aged women. PCOS is often accompanied with insulin resistance (IR) which is an essential pathological factor. Although there is no known cure for PCOS, cangfudaotan (CFDT) decoction is widely used for the treatment of PCOS; nevertheless, the underlying mechanism is not clear. In this study, 40 Sprague-Dawley (SD) rats (female) were randomized to 4 groups, namely the control group, PCOS group, PCOS+CFDT group, and PCOS+metformin group. The rats in the control group were fed a normal-fat diet, intraperitoneally injected with 0.5% carboxymethyl cellulose (CMC, 1 mL/kg/d) for 21 days and orally given saline (1 mL/kg/d) for the next 4 weeks. The rats in the PCOS group, PCOS+CFDT group, and PCOS+Metformin group were fed a high-fat diet (HFD) and intraperitoneally injected with letrozole (1.0 mg/kg) for 21 days. During this period, we recorded the body weight, estrous cycles, and rate of pregnancy in all rats. We also observed the ovarian ultrastructure. Blood glucose indices, serum hormones, and inflammatory factors were also recorded. Then, we detected apoptotic and mitochondrial function, and observed mitochondria in ovarian granular cells by transmission electron microscopy. We also detected genes of ASK1/JNK pathway at mRNA and protein levels. The results showed that CFDT alleviated pathohistological damnification and apoptosis in PCOS rat model. In addition, CFDT improved ovarian function, reduced inflammatory response, inhibited apoptosis of granular cells, and inhibited the operation of ASK1/JNK pathway. These findings demonstrate the occurrence of ovary mitochondrial dysfunction and granular cell apoptosis in PCOS. CFDT can relieve mitochondria-dependent apoptosis by inhibiting the ASK1/JNK pathway in PCOS rats.

Celastrol attenuates high-fructose diet-induced inflammation and insulin resistance via inhibition of 11β-hydroxysteroid dehydrogenase type 1 activity in rat adipose tissues

High fructose consumption has been linked to low-grade inflammation and insulin resistance that results in increased intracellular 11ß-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activity. Celastrol, a pentacyclic triterpene, has been demonstrated to exhibit multifaceted targets to attenuate various metabolic diseases associated with inflammation. However, the underlying mechanisms by which celastrol exerts its attributive properties on high fructose diet (HFrD)-induced metabolic syndrome remain elusive. Herein, the present study was aimed to elucidate the mechanistic targets of celastrol co-administrations upon HFrD in rats and evaluate its potential to modulate 11β-HSD1 activity. Celastrol remarkably improved glucose tolerance, lipid profiles, and insulin sensitivity along with suppression of hepatic glucose production. In rat adipose tissues, celastrol attenuated nuclear factor-kappa B (NF-κB)-driven inflammation, reduced c-Jun N-terminal kinases (JNK) phosphorylation, and mitigated oxidative stress via upregulated genes expression involved in mitochondrial biogenesis. Furthermore, insulin signaling pathways were significantly improved through the restoration of Akt phosphorylation levels at Ser473 and Thr308 residues. Celastrol exhibited a potent, selective and specific inhibitor of intracellular 11β-HSD1 towards oxidoreductase activity (IC₅₀ value = 4.3 nM) in comparison to other HSD-related enzymes. Inhibition of 11β-HSD1 expression in rat adipose microsomes reduced the availability of its cofactor NADPH and substrate H6PDH in couple to upregulated mRNA and protein expressions of glucocorticoid receptor. In conclusion, our results underscore the most likely conceivable mechanisms exhibited by celastrol against HFrD-induced metabolic dysregulations mainly through attenuating inflammation and insulin resistance, at least via specific inhibitions on 11β-HSD1 activity in adipose tissues.

Fructose Consumption and Hepatocellular Carcinoma Promotion

Hepatocellular carcinoma (HCC) accounts for 85% of primary liver cancer, the third most common cause of cancer-related deaths worldwide. Its incidence has been increasing in both men and women. In Western countries, high-calorie diets, mainly rich in carbohydrates such as fructose, represent a significant concern due to their repercussions on the population’s health. A high-fructose diet is related to the development of Metabolic-Associated Fatty Liver Disease (MAFLD), formerly named Non-Alcoholic Fatty Liver Disease (NAFLD), and the progression of HCC as it potentiates the lipogenic pathway and the accumulation of lipids. However, fructose metabolism seems to be different between the stages of the disease, carrying out a metabolic reprogramming to favor the proliferation, inflammation, and metastatic properties of cancer cells in HCC. This review focuses on a better understanding of fructose metabolism in both scenarios: MAFLD and HCC.

The Interplay between Insulin Resistance, Inflammation, Oxidative Stress, Base Excision Repair and Metabolic Syndrome in Nonalcoholic Fatty Liver Disease

One of the most common chronic liver disorders, affecting mainly people in Western countries, is nonalcoholic fatty liver disease (NAFLD). Unfortunately, its pathophysiological mechanism is not fully understood, and no dedicated treatment is available. Simple steatosis can lead to nonalcoholic steatohepatitis and even to fibrosis, cancer, and cirrhosis of the liver. NAFLD very often occurs in parallel with type 2 diabetes mellitus and in obese people. Furthermore, it is much more likely to develop in patients with metabolic syndrome (MS), whose criteria include abdominal obesity, elevated blood triacylglycerol level, reduced high-density lipoprotein cholesterol level, increased blood pressure, and high fasting glucose. An important phenomenon in MS is also insulin resistance (IR), which is very common in NAFLD. Liver IR and NAFLD development are linked through an interaction between the accumulation of free fatty acids, hepatic inflammation, and increased oxidative stress. The liver is particularly exposed to elevated levels of reactive oxygen species due to a large number of mitochondria in hepatocytes. In these organelles, the main DNA repair pathway is base excision repair (BER). The present article will illustrate how impairment of BER may be related to the development of NAFLD.

Gut and liver metabolic responses to dietary fructose - are they reversible or persistent after switching to a healthy diet?

The link between increased fructose intake and induction of gut and liver dysfunction has been established, while it remains to be understood whether this damage is reversible, particularly in the young population, in which the intake of fructose has reached dramatic levels. To this end, young (30 days old) rats were fed a fructose-rich or control diet for 3 weeks to highlight the early response of the gut and liver to increased fructose intake. After this period, fructose-fed rats were returned to a control diet for 3 weeks and compared to the rats that received the control diet for the entire period to identify whether fructose-induced changes in the gut-liver axis persist or not after switching back to a control diet. Glucose transporter 5 and the tight junction protein occludin were assessed in the ileum and colon. Markers of inflammation and redox homeostasis as well as fructose and uric acid levels were also evaluated in the ileum, colon and liver. From the whole data, it is seen that metabolic derangement elicited by a fructose-rich diet, even after a brief period of intake, is fully reversed in the liver by a period of fructose withdrawal, while the alterations persist in the gut, especially in the ileum. In conclusion, given the increasing consumption of fructose-rich foods in young populations, the present results highlight the risk arising from gut persistent alterations even after the end of a fructose-rich diet. Therefore, dietary recommendations of reducing the intake of this simple sugar is mandatory to avoid not only the related metabolic alterations but also the persistence of these detrimental changes.

Mitochondrial DNA copy number and trimethylamine levels in the blood: New insights on cardiovascular disease biomarkers

Among cardiovascular disease (CVD) biomarkers, the mitochondrial DNA copy number (mtDNAcn) is a promising candidate. A growing attention has been also dedicated to trimethylamine-N-oxide (TMAO), an oxidative derivative of the gut metabolite trimethylamine (TMA). With the aim to identify biomarkers predictive of CVD, we investigated TMA, TMAO, and mtDNAcn in a population of 389 coronary artery disease (CAD) patients and 151 healthy controls, in association with established risk factors for CVD (sex, age, hypertension, smoking, diabetes, glomerular filtration rate [GFR]) and troponin, an established marker of CAD. MtDNAcn was significantly lower in CAD patients; it correlates with GFR and TMA, but not with TMAO. A biomarker including mtDNAcn, sex, and hypertension (but neither TMA nor TMAO) emerged as a good predictor of CAD. Our findings support the mtDNAcn as a promising plastic biomarker, useful to monitor the exposure to risk factors and the efficacy of preventive interventions for a personalized CAD risk reduction.

High fructose induced osteogenic differentiation of human valve interstitial cells via activating PI3K/AKT/mitochondria signaling

Background

Aortic valve stenosis (AS) is a common, lethal cardiovascular disease. There is no cure except the valve replacement at last stage. Therefore, an understanding of the detail mechanism is imperative to prevent and intervene AS. Metabolic syndrome (MetS) is one of the major risk factors of AS whereas fructose overconsuming tops the list of MetS risk factors. However, whether the fructose under physiological level induces AS is currently unknown.

Methods

The human valve interstitial cells (hVICs), a crucial source to develop calcification, were co-incubated with fructose at 2 or 20 mM to mimic the serum fructose at fasting or post-fructose consumption, respectively, for 24 h. The cell proliferation was evaluated by WST-1 assays. The expressions of osteogenic and fibrotic proteins, PI3K/AKT signaling, insulin receptor substrate 1 and mitochondrial dynamic proteins were detected by Western blot analyses. The mitochondrial oxidative phosphorylation (OXPHOS) was examined by Seahorse analyzer.

Results

hVICs proliferation was significantly suppressed by 20 mM fructose. The expressions of alkaline phosphatase (ALP) and osteocalcin were enhanced concurrent with the upregulated PI3K p85, AKT, phospho(p)S473-AKT, and pS636-insulin receptor substrate 1 (p-IRS-1) by high fructose. Moreover, ATP production capacity and maximal respiratory capacity were enhanced in the high fructose groups. Synchronically, the expressions of mitochondrial fission 1 and optic atrophy type 1 were increased.

Conclusions

These results suggested that high fructose stimulated the osteogenic differentiation of hVICs via the activation of PI3K/AKT/mitochondria signaling at the early stage. These results implied that high fructose at physiological level might have a direct, hazard effect on the progression of AS.

Fructose and the Liver

Chronic diseases represent a major challenge in world health. Metabolic syndrome is a constellation of disturbances affecting several organs, and it has been proposed to be a liver-centered condition. Fructose overconsumption may result in insulin resistance, oxidative stress, inflammation, elevated uric acid levels, increased blood pressure, and increased triglyceride concentrations in both the blood and liver. Non-alcoholic fatty liver disease (NAFLD) is a term widely used to describe excessive fatty infiltration in the liver in the absence of alcohol, autoimmune disorders, or viral hepatitis; it is attributed to obesity, high sugar and fat consumption, and sedentarism. If untreated, NAFLD can progress to nonalcoholic steatohepatitis (NASH), characterized by inflammation and mild fibrosis in addition to fat infiltration and, eventually, advanced scar tissue deposition, cirrhosis, and finally liver cancer, which constitutes the culmination of the disease. Notably, fructose is recognized as a major mediator of NAFLD, as a significant correlation between fructose intake and the degree of inflammation and fibrosis has been found in preclinical and clinical studies. Moreover, fructose is a risk factor for liver cancer development. Interestingly, fructose induces a number of proinflammatory, fibrogenic, and oncogenic signaling pathways that explain its deleterious effects in the body, especially in the liver.

Maternal high-fructose diet induced early-onset retinopathy via the suppression of synaptic plasticity mediated by mitochondrial dysfunction

Retinopathy is a leading cause of blindness, and there is currently no cure. Earlier identification of the progression of retinopathy could provide a better chance for intervention. Diet has profound effects on retinal function. A maternal high-fructose diet (HFD) triggers diseases in multiple organs. However, whether maternal HFD impairs retinal function in adult offspring is currently unknown. By using the rodent model of maternal HFD during pregnancy and lactation, our data indicated a reduced b-wave of electroretinography (ERG) in HFD female offspring at 3 mo of age compared with age-matched offspring of dams fed regular chow (ND). Immunofluorescence and Western blot analyses indicated that the distributions and expressions of synaptophysin, postsynaptic density protein 95 (PSD95), and phospho(p)-Ca²⁺/calmodulin-stimulated protein kinase IIα (CaMKIIα) were significantly suppressed in the HFD group. Furthermore, the ATP content and the mitochondrial respiratory protein, Mt CPX 4-2, were decreased. Moreover, the expressions of peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) and mitochondrial transcription factor A (TFAM) in the retina of the HFD group were downregulated. Treatment with coenzyme Q₁₀ (Q10), a key mediator of the electron transport chain, effectively reversed these abovementioned dysfunctions. Together, these results suggested that maternal HFD impaired retinal function in adult female offspring. The mechanism underlying early-onset retinopathy may involve the reduction in the capacity of mitochondrial energy production and the suppression of synaptic plasticity. Most importantly, mitochondria could be a feasible target to reprogram maternal HFD-damaged retinal function.NEW & NOTEWORTHY In this study, we provide novel evidence that maternal high-fructose diet during gestation and lactation could induce early-onset retinopathy in adult female offspring. Of note, the insufficient energy content, downregulated mitochondrial respiratory complex 4-2, and impaired mitochondrial biogenesis might contribute to the decrease of synaptic plasticity resulting in retinal function suppression. Oral application with coenzyme Q₁₀ for 4 wk could at least partially reverse the aforementioned molecular events and retinal function.

Tanshinone IIA Combined With Cyclosporine A Alleviates Lung Apoptosis Induced by Renal Ischemia-Reperfusion in Obese Rats

Acute lung injury (ALI), which is induced by renal ischemia-reperfusion (IR), is one of the leading causes of acute renal IR-related death. Obesity raises the frequency and severity of acute kidney injury (AKI) and ALI. Tanshinone IIA (TIIA) combined with cyclosporine A (CsA) was employed to lessen the lung apoptosis led by renal IR and to evaluate whether TIIA combined with CsA could alleviate lung apoptosis by regulating mitochondrial function through the PI3K/Akt/Bad pathway in obese rats. Hematoxylin-eosin (HE) staining was used to assess the histology of the lung injury. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) was used to assess apoptosis of the lung. Electron microscopy was used to assess mitochondrial morphology in lung cells. Arterial blood gas and pulmonary function were used to assess the external respiratory function. Mitochondrial function was used to assess the internal respiratory function and mitochondrial dynamics and biogenesis. Western blot (WB) was used to examine the PI3K/Akt/Bad pathway-related proteins. TIIA combined with CsA can alleviate lung apoptosis by regulating mitochondrial function through the PI3K/Akt/Bad pathway in obese rats.

Tanshinone IIA combined with CsA inhibit myocardial cell apoptosis induced by renal ischemia-reperfusion injury in obese rats

BACKGROUND

Acute myocardial injury (AMI), which is induced by renal ischemia-reperfusion (IR), is a significant cause of acute kidney injury (AKI)-related associated death. Obesity increases the severity and frequency of AMI and AKI. Tanshinone IIA (TIIA) combined with cyclosporine A (CsA) pretreatment was used to alleviate myocardial cell apoptosis induced by renal IR, and to determine whether TIIA combined with CsA would attenuate myocardial cell apoptosis by modulating mitochondrial function through the PI3K/Akt/Bad pathway in obese rats.

METHODS

Male rates were fed a high fat diet for 8 weeks to generate obesity. AKI was induced by 30 min of kidney ischemia followed 24 h of reperfusion. Obese rats were given TIIA (10 mg/kg·d) for 2 weeks and CsA (5 mg/kg) 30 min before renal IR. After 24 h of reperfusion, the rats were anaesthetized, the blood were fetched from the abdominal aorta and kidney were fetched from abdominal cavity, then related indicators were examined.

RESULTS

TIIA combined with CsA can alleviate the pathohistological injury and apoptosis induced by renal IR in myocardial cells. TIIA combined with CsA improved cardiac function after renal ischemia (30 min)-reperfusion (24 h) in obese rats. At the same time, TIIA combined with CsA improved mitochondrial function. Abnormal function of mitochondria was supported by decreases in respiration controlling rate (RCR), intracellular adenosine triphosphate (ATP), oxygen consumption rate, and mitochondrial membrane potential (MMP), and increases in mitochondrial reactive oxygen species (ROS), opening of the mitochondrial permeability transition pore (mPTP), mitochondrial DNA damage, and mitochondrial respiratory chain complex enzymes. The injury of mitochondrial dynamic function was assessed by decrease in dynamin-related protein 1 (Drp1), and increases in mitofusin1/2 (Mfn1/2), and mitochondrial biogenesis injury was assessed by decreases in PPARγ coactivator-1-α (PGC-1), nucleo respiratory factor1 (Nrf1), and transcription factor A of mitochondrial (TFam).

CONCLUSION

We used isolated mitochondria from rat myocardial tissues to demonstrate that myocardial mitochondrial dysfunction occurred along with renal IR to induce myocardial cell apoptosis; obesity aggravated apoptosis. TIIA combined with CsA attenuated myocardial cell apoptosis by modulating mitochondrial function through the PI3K/Akt/Bad pathway in obese rats.

Exogenous exposure to dihydroxyacetone mimics high fructose induced oxidative stress and mitochondrial dysfunction

Dihydroxyacetone (DHA) is a three-carbon sugar that is the active ingredient in sunless tanning products and a by-product of electronic cigarette (e-cigarette) combustion. Increased use of sunless tanning products and e-cigarettes has elevated exposures to DHA through inhalation and absorption. Studies have confirmed that DHA is rapidly absorbed into cells and can enter into metabolic pathways following phosphorylation to dihydroxyacetone phosphate (DHAP), a product of fructose metabolism. Recent reports have suggested metabolic imbalance and cellular stress results from DHA exposures. However, the impact of elevated exposure to DHA on human health is currently under-investigated. We propose that exogenous exposures to DHA increase DHAP levels in cells and mimic fructose exposures to produce oxidative stress, mitochondrial dysfunction, and gene and protein expression changes. Here, we review cell line and animal model exposures to fructose to highlight similarities in the effects produced by exogenous exposures to DHA. Given the long-term health consequences of fructose exposure, this review emphasizes the pressing need to further examine DHA exposures from sunless tanning products and e-cigarettes.

Organelle dynamics of endothelial mitochondria in diabetic angiopathy

Diabetes, a chronic non-communicable disease, has become one of the most serious and critical public health problems with increasing incidence trends. Chronic vascular complications are the major causes of disability and death in diabetic patients with endothelial dysfunction. Diabetes is intimately associated with endothelial mitochondrial dysfunction, indicated by increased oxidative stress, decreased biogenesis, increased DNA damage, and weakened autophagy in mitochondria. All these morphological and functional changes of mitochondria play important roles in diabetic endothelial dysfunction. Herein, we reviewed the roles and mechanisms of endothelial mitochondrial dysfunction, particularly mitochondrial dynamics in the vascular complications of diabetes and summarized the potential mitochondria-targeted therapies in diabetic vascular complications.

Non-hematopoietic IL-4Rα expression contributes to fructose-driven obesity and metabolic sequelae

OBJECTIVE

The risks of excess sugar intake in addition to high-fat diet consumption on immunopathogenesis of obesity-associated metabolic diseases are poorly defined. Interleukin-4 (IL-4) and IL-13 signaling via IL-4Rα regulates adipose tissue lipolysis, insulin sensitivity, and liver fibrosis in obesity. However, the contribution of IL-4Rα to sugar rich diet-driven obesity and metabolic sequelae remains unknown.

METHODS

WT, IL-4Rα-deficient (IL-4Rα^-/-) and STAT6-deficient mice (STAT6^-/-) male mice were fed low-fat chow, high fat (HF) or HF plus high carbohydrate (HC/fructose) diet (HF + HC). Analysis included quantification of: (i) body weight, adiposity, energy expenditure, fructose metabolism, fatty acid oxidation/synthesis, glucose dysmetabolism and hepatocellular damage; (ii) the contribution of the hematopoietic or non-hematopoietic IL-4Rα expression; and (iii) the relevance of IL-4Rα downstream canonical STAT6 signaling pathway in this setting.

RESULTS

We show that IL-4Rα regulated HF + HC diet-driven weight gain, whole body adiposity, adipose tissue inflammatory gene expression, energy expenditure, locomotor activity, glucose metabolism, hepatic steatosis, hepatic inflammatory gene expression and hepatocellular damage. These effects were potentially, and in part, dependent on non-hematopoietic IL-4Rα expression but were independent of direct STAT6 activation. Mechanistically, hepatic ketohexokinase-A and C expression was dependent on IL-4Rα, as it was reduced in IL-4Rα-deficient mice. KHK activity was also affected by HF + HC dietary challenge. Further, reduced expression/activity of KHK in IL-4Rα mice had a significant effect on fatty acid oxidation and fatty acid synthesis pathways.

CONCLUSION

Our findings highlight potential contribution of non-hematopoietic IL-4Rα activation of a non-canonical signaling pathway that regulates the HF + HC diet-driven induction of obesity and severity of obesity-associated sequelae.

Sweet but Bitter: Focus on Fructose Impact on Brain Function in Rodent Models

Fructose consumption has drastically increased during the last decades due to the extensive commercial use of high-fructose corn syrup as a sweetener for beverages, snacks and baked goods. Fructose overconsumption is known to induce obesity, dyslipidemia, insulin resistance and inflammation, and its metabolism is considered partially responsible for its role in several metabolic diseases. Indeed, the primary metabolites and by-products of gut and hepatic fructolysis may impair the functions of extrahepatic tissues and organs. However, fructose itself causes an adenosine triphosphate (ATP) depletion that triggers inflammation and oxidative stress. Many studies have dealt with the effects of this sugar on various organs, while the impact of fructose on brain function is, to date, less explored, despite the relevance of this issue. Notably, fructose transporters and fructose metabolizing enzymes are present in brain cells. In addition, it has emerged that fructose consumption, even in the short term, can adversely influence brain health by promoting neuroinflammation, brain mitochondrial dysfunction and oxidative stress, as well as insulin resistance. Fructose influence on synaptic plasticity and cognition, with a major impact on critical regions for learning and memory, was also reported. In this review, we discuss emerging data about fructose effects on brain health in rodent models, with special reference to the regulation of food intake, inflammation, mitochondrial function and oxidative stress, insulin signaling and cognitive function.

Mitochondrial DNA and Neurodegeneration: Any Role for Dietary Antioxidants?

The maintenance of the mitochondrial function is essential in preventing and counteracting neurodegeneration. In particular, mitochondria of neuronal cells play a pivotal role in sustaining the high energetic metabolism of these cells and are especially prone to oxidative damage. Since overproduction of reactive oxygen species (ROS) is involved in the pathogenesis of neurodegeneration, dietary antioxidants have been suggested to counteract the detrimental effects of ROS and to preserve the mitochondrial function, thus slowing the progression and limiting the extent of neuronal cell loss in neurodegenerative disorders. In addition to their role in the redox-system homeostasis, mitochondria are unique organelles in that they contain their own genome (mtDNA), which acts at the interface between environmental exposures and the molecular triggers of neurodegeneration. Indeed, it has been demonstrated that mtDNA (including both genetics and, from recent evidence, epigenetics) might play relevant roles in modulating the risk for neurodegenerative disorders. This mini-review describes the link between the mitochondrial genome and cellular oxidative status, with a particular focus on neurodegeneration; moreover, it provides an overview on potential beneficial effects of antioxidants in preserving mitochondrial functions through the protection of mtDNA.

Diet induced the change of mtDNA copy number and metabolism in Angus cattle

Background

Grass-fed and grain-fed Angus cattle differ in the diet regimes. However, the intricate mechanisms of different beef quality and other phenotypes induced by diet differences are still unclear. Diet affects mitochondrial function and dynamic behavior in response to changes in energy demand and supply. In this study, we examined the mtDNA copy number, mitochondria-related genes expression, and metabolic biomarkers in grass-fed and grain-fed Angus cattle.

Results

We found that the grass-fed group had a higher mtDNA copy number than the grain-fed group. Among different tissues, the mtDNA copy number was the highest in the liver than muscle, rumen, and spleen. Based on the transcriptome of the four tissues, a lower expression of mtDNA-encoded genes in the grass-fed group compared to the grain-fed group was discovered. For the mitochondria-related nuclear genes, however, most of them were significantly down-regulated in the muscle of the grass-fed group and up-regulated in the other three tissues. In which, COX6A2, POLG2, PPIF, DCN, and NDUFA12, involving in ATP synthesis, mitochondrial replication, transcription, and maintenance, might contribute to the alterations of mtDNA copy number and gene expression. Meanwhile, 40 and 23 metabolic biomarkers were identified in the blood and muscle of the grain-fed group compared to a grass-fed group, respectively. Integrated analysis of the altered metabolites and gene expression revealed the high expression level of MDH1 in the grain-fed group might contribute to the mitochondrial NADH oxidation and spermidine metabolism for adapting the deletion mtDNA copy number.

Conclusions

Overall, the study may provide further deep insight into the adaptive and regulatory modulations of the mitochondrial function in response to different feeding systems in Angus cattle.

Higher ultra-processed food intake is associated with higher DNA damage in healthy adolescents

Ultra-processed food is one of the main contributors to energy supply and consumption in food systems worldwide, and evidence of their detrimental health outcomes in humans is emerging. This study aimed to assess ultra-processed food intake and its association with urinary levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG), a biomarker of DNA oxidative damage, in 139 healthy adolescents in Karaj City in Iran. Usual dietary intake was measured using a 168-item validated FFQ. The daily intake of ultra-processed food consumption was determined through the classification of NOVA, and general linear models were used to compare the urinary levels of 8-OHdG/creatinine (ng/mg creatinine) within tertiles of ultra-processed food intake. Adolescents in the higher tertile of ultra-processed food consumption had a significantly higher mean level of urinary 8-OHdG/creatinine in comparison with the lower tertiles in the crude model (Pfor trend: 0·003) and after adjustment for confounding variables, including total energy intake, sex, age, BMI for age Z-score, obesity and physical activity (Pfor trend: 0·004). This association was still significant after adjusting for dietary intake of whole grains, nuts, legumes, the ratio of MUFA:SFA (g/d) and Mediterranean dietary score (Pfor trend: 0·002). More studies are needed to explore the determinants of ultra-processed food supply, demand, consumption and health effects; such studies should be applied to develop evidence-informed policies and regulatory mechanisms to improve children’s and adolescents’ food environment policymaking and legislation with special attention to ultra-processed food.

L-Carnitine counteracts in vitro fructose-induced hepatic steatosis through targeting oxidative stress markers

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is defined by excessive lipid accumulation in the liver and involves an ample spectrum of liver diseases, ranging from simple uncomplicated steatosis to cirrhosis and hepatocellular carcinoma. Accumulating evidence demonstrates that high fructose intake enhances NAFLD development and progression promoting inhibition of mitochondrial β-oxidation of long-chain fatty acids and oxidative damages. L-Carnitine (LC), involved in β-oxidation, has been used to reduce obesity caused by high-fat diet, which is beneficial to ameliorating fatty liver diseases. Moreover, in the recent years, various studies have established LC anti-oxidative proprieties. The objective of this study was to elucidate primarily the underlying anti-oxidative mechanisms of LC in an in vitro model of fructose-induced liver steatosis.

METHODS

Human hepatoma HepG2 cells were maintained in medium supplemented with LC (5 mM LC) with or without 5 mM fructose (F) for 48 h and 72 h. In control cells, LC or F was not added to medium. Fat deposition, anti-oxidative, and mitochondrial homeostasis were investigated.

RESULTS

LC supplementation decreased the intracellular lipid deposition enhancing AMPK activation. However, compound C (AMPK inhibitor-10 μM), significantly abolished LC benefits in F condition. Moreover, LC, increasing PGC1 α expression, ameliorates mitochondrial damage-F induced. Above all, LC reduced ROS production and simultaneously increased protein content of antioxidant factors, SOD2 and Nrf2.

CONCLUSION

Our data seemed to show that LC attenuate fructose-mediated lipid accumulation through AMPK activation. Moreover, LC counteracts mitochondrial damages and reactive oxygen species production restoring antioxidant cellular machine. These findings provide new insights into LC role as an AMPK activator and anti-oxidative molecule in NAFLD.

ER Stress Amelioration by Saxagliptin Protects the Liver Against Fructose-induced Insulin Resistance

BACKGROUND/AIM

The study is aimed to demonstrate whether saxagliptin treatment may reduce endoplasmic reticulum (ER) stress, oxidative damage, and inflammation in the liver of fructose-induced insulin resistance (IR) rats.

MATERIAL AND METHODS

Twenty-eight rats were divided as control, IR, saxagliptin treatment (ST) and IR+ST groups. IR caused by fructose (10%) administration for 10 weeks and, ST was administered for 15 d. The liver tissues were obtained from rats. ER stress markers were analyzed using Real-Time PCR. Oxidative stress was measured. The inflammation in the liver was detected by the streptavidin-biotin immunostaining method.

RESULTS

The values of total oxidant/antioxidant status were the same between control and IR rats. The numbers of IL-6, NF-κB and PPARγ immune⁺ cells showed significant changes in the liver among four groups. The increased mRNA expression levels of ER stress and apoptosis markers as GRP78, PERK, IRE1α, ATF-4 and -6, CHOP, Caspase-3, -8, -9 and -12 in IR reduced with ST.

CONCLUSION

These findings indicate that saxagliptin treatment may ameliorate IR by reducing ER stress rather than inflammation and oxidative stress in the liver.

Chronic exercise provides renal-protective effects with upregulation of fatty acid oxidation in the kidney of high fructose-fed rats

Excessive fructose intake causes metabolic syndrome and lipid accumulation in the kidney and leads to renal dysfunction and damage. Exercise (Ex) improves lipids regulation, but the mechanisms are unclarified in the kidney. In the present study, male Sprague-Dawley rats were allocated to groups fed with control or high-fructose (HFr) diet. Part of rats in each group underwent aerobic treadmill Ex for 12 wk. Drug treatment was performed as the fenofibrate gavage during the last 4 wk on HFr diet-fed rats. Renal function, histological changes, and expression of regulators involved in fatty acid (FA) metabolism were assessed. In CON diet-fed groups, Ex did not affect renal function or histology and significantly increased renal expression of FA β-oxidation regulators including acyl-CoA dehydrogenases (CADs), acyl-CoA oxidase, peroxisome proliferator-activated receptor (PPAR)-α, and PPAR-γ coactivator (PGC)-1α and lipogenic factors including acetyl-CoA carboxylase (ACCα), FA synthase (FAS), and sterol regulatory element-binding protein 1c. HFr caused albuminuria, lipid accumulation, and renal pathohistological changes, which were attenuated by Ex but not by fenofibrate. HFr decreased renal expression of medium- and short-chain CADs and PPAR-α and increased renal expression of ACCα, FAS, and sterol regulatory element-binding protein 1c. Ex increased expression of CADs, carnitine palmitoyltransferase type I, acyl-CoA oxidase, PPAR-α, and PGC-1α and decreased renal expression of ACCα and FAS in HFr diet-fed rats. The Ex-induced FA metabolism alteration was similar to that in the fenofibrate-treated group. In conclusion, the present study indicates that Ex enhanced renal FA metabolism, which might protect the kidney in lipid dysregulation diseases.

Candidate SNP Markers of Atherogenesis Significantly Shifting the Affinity of TATA-Binding Protein for Human Gene Promoters show stabilizing Natural Selection as a Sum of Neutral Drift Accelerating Atherogenesis and Directional Natural Selection Slowing It

(1) Background: The World Health Organization (WHO) regards atherosclerosis-related myocardial infarction and stroke as the main causes of death in humans. Susceptibility to atherogenesis-associated diseases is caused by single-nucleotide polymorphisms (SNPs). (2) Methods: Using our previously developed public web-service SNP_TATA_Comparator, we estimated statistical significance of the SNP-caused alterations in TATA-binding protein (TBP) binding affinity for 70 bp proximal promoter regions of the human genes clinically associated with diseases syntonic or dystonic with atherogenesis. Additionally, we did the same for several genes related to the maintenance of mitochondrial genome integrity, according to present-day active research aimed at retarding atherogenesis. (3) Results: In dbSNP, we found 1186 SNPs altering such affinity to the same extent as clinical SNP markers do (as estimated). Particularly, clinical SNP marker rs2276109 can prevent autoimmune diseases via reduced TBP affinity for the human MMP12 gene promoter and therefore macrophage elastase deficiency, which is a well-known physiological marker of accelerated atherogenesis that could be retarded nutritionally using dairy fermented by lactobacilli. (4) Conclusions: Our results uncovered SNPs near clinical SNP markers as the basis of neutral drift accelerating atherogenesis and SNPs of genes encoding proteins related to mitochondrial genome integrity and microRNA genes associated with instability of the atherosclerotic plaque as a basis of directional natural selection slowing atherogenesis. Their sum may be stabilizing the natural selection that sets the normal level of atherogenesis.

Fructose and hepatic insulin resistance

Excessive caloric intake in a form of high-fat diet (HFD) was long thought to be the major risk factor for development of obesity and its complications, such as fatty liver disease and insulin resistance. Recently, there has been a paradigm shift and more attention is attributed to the effects of sugar-sweetened beverages (SSBs) as one of the culprits of the obesity epidemic. In this review, we present the data invoking fructose intake with development of hepatic insulin resistance in human studies and discuss the pathways by which fructose impairs hepatic insulin action in experimental animal models. First, we described well-characterized pathways by which fructose metabolism indirectly leads to hepatic insulin resistance. These include unequivocal effects of fructose to promote de novo lipogenesis (DNL), impair fatty acid oxidation (FAO), induce endoplasmic reticulum (ER) stress and trigger hepatic inflammation. Additionally, we entertained the hypothesis that fructose can directly impede insulin signaling in the liver. This appears to be mediated by reduced insulin receptor and insulin receptor substrate 2 (IRS2) expression, increased protein-tyrosine phosphatase 1B (PTP1b) activity, whereas knockdown of ketohexokinase (KHK), the rate-limiting enzyme of fructose metabolism, increased insulin sensitivity. In summary, dietary fructose intake strongly promotes hepatic insulin resistance via complex interplay of several metabolic pathways, at least some of which are independent of increased weight gain and caloric intake. The current evidence shows that the fructose, but not glucose, component of dietary sugar drives metabolic complications and contradicts the notion that fructose is merely a source of palatable calories that leads to increased weight gain and insulin resistance.

Is an "Epigenetic Diet" for Migraines Justified? The Case of Folate and DNA Methylation

Migraines are a common disease with limited treatment options and some dietary factors are recognized to trigger headaches. Although migraine pathogenesis is not completely known, aberrant DNA methylation has been reported to be associated with its occurrence. Folate, an essential micronutrient involved in one-carbon metabolism and DNA methylation, was shown to have beneficial effects on migraines. Moreover, the variability of the methylenetetrahydrofolate reductase gene, important in both folate metabolism and migraine pathogenesis, modulates the beneficial effects of folate for migraines. Therefore, migraine could be targeted by a folate-rich, DNA methylation-directed diet, but there are no data showing that beneficial effects of folate consumption result from its epigenetic action. Furthermore, contrary to epigenetic drugs, epigenetic diets contain many compounds, some yet unidentified, with poorly known or completely unknown potential to interfere with the epigenetic action of the main dietary components. The application of epigenetic diets for migraines and other diseases requires its personalization to the epigenetic profile of a patient, which is largely unknown. Results obtained so far do not warrant the recommendation of any epigenetic diet as effective in migraine prevention and therapy. Further studies including a folate-rich diet fortified with valproic acid, another modifier of epigenetic profile effective in migraine prophylaxis, may help to clarify this issue.

Mitochondrial Dysfunction in the Transition from NASH to HCC

The liver constantly adapts to meet energy requirements of the whole body. Despite its remarkable adaptative capacity, prolonged exposure of liver cells to harmful environmental cues (such as diets rich in fat, sugar, and cholesterol) results in the development of chronic liver diseases (including non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH)) that can progress to hepatocellular carcinoma (HCC). The pathogenesis of these diseases is extremely complex, multifactorial, and poorly understood. Emerging evidence suggests that mitochondrial dysfunction or maladaptation contributes to detrimental effects on hepatocyte bioenergetics, reactive oxygen species (ROS) homeostasis, endoplasmic reticulum (ER) stress, inflammation, and cell death leading to NASH and HCC. The present review highlights the potential contribution of altered mitochondria function to NASH-related HCC and discusses how agents targeting this organelle could provide interesting treatment strategies for these diseases.

Plasma Fibroblast Growth Factor 21 Is Associated With Severity of Nonalcoholic Steatohepatitis in Patients With Obesity and Type 2 Diabetes

CONTEXT

The relationship between plasma fibroblast growth factor 21 (FGF21), insulin resistance, and steatohepatitis has not been systematically assessed.

OBJECTIVE

To determine if higher plasma FGF21 is associated with worse steatohepatitis on liver biopsy in patients with nonalcoholic fatty liver disease (NAFLD).

DESIGN AND SETTING

Cross-sectional study in a university hospital.

PATIENTS INTERVENTIONS AND MAIN OUTCOME MEASURES

Patients with a body mass index >25 (n = 187) underwent: (i) euglycemic hyperinsulinemic clamp to assess tissue-specific insulin resistance (IR); (ii) liver magnetic resonance spectroscopy for intrahepatic triglyceride quantification, (iii) liver biopsy (if NAFLD present; n = 146); and (iv) fasting plasma FGF21 levels.

METHODS AND RESULTS

Patients were divided into three groups: (i) No NAFLD (n = 41); (ii) No nonalcoholic steatohepatitis (NASH) (patients with isolated steatosis or borderline NASH; n = 52); and (iii) NASH (patients with definite NASH; n = 94). Groups were well-matched for age/sex, prevalence of type 2 diabetes mellitus, and hemoglobin A1c. During euglycemic hyperinsulinemic insulin clamp, insulin sensitivity in skeletal muscle and adipose tissue worsened from No NAFLD to NASH (both P < 0.001). Plasma FGF21 levels correlated inversely with insulin sensitivity in adipose tissue (r = -0.17, P = 0.006) and skeletal muscle (r = -0.23, P = 0.007), but not with liver insulin sensitivity. Plasma FGF21 was higher in patients with NASH (453 ± 262 pg/mL) when compared with the No NASH (341 ± 198 pg/mL, P = 0.03) or No NAFLD (325 ± 289 pg/mL, P = 0.02) groups. Plasma FGF21 increased with the severity of necroinflammation (P = 0.02), and most significantly with worse fibrosis (P < 0.001), but not with worsening steatosis (P = 0.60).

CONCLUSIONS

Plasma FGF21 correlates with severity of steatohepatitis, in particular of fibrosis, in patients with NASH. Measurement of FGF21 may help identify patients at the highest risk of disease progression.