Manganese [III] Tetrakis [5,10,15,20]-Benzoic Acid Porphyrin Reduces Adiposity and Improves Insulin Action in Mice with Pre-Existing Obesity

Redox Balance in Type 2 Diabetes: Therapeutic Potential and the Challenge of Antioxidant-Based Therapy

Oxidative stress is an important factor in the development of type 2 diabetes (T2D) and associated complications. Unfortunately, most clinical studies have failed to provide sufficient evidence regarding the benefits of antioxidants (AOXs) in treating this disease. Based on the known complexity of reactive oxygen species (ROS) functions in both the physiology and pathophysiology of glucose homeostasis, it is suggested that inappropriate dosing leads to the failure of AOXs in T2D treatment. To support this hypothesis, the role of oxidative stress in the pathophysiology of T2D is described, together with a summary of the evidence for the failure of AOXs in the management of diabetes. A comparison of preclinical and clinical studies indicates that suboptimal dosing of AOXs might explain the lack of benefits of AOXs. Conversely, the possibility that glycemic control might be adversely affected by excess AOXs is also considered, based on the role of ROS in insulin signaling. We suggest that AOX therapy should be given in a personalized manner according to the need, which is the presence and severity of oxidative stress. With the development of gold-standard biomarkers for oxidative stress, optimization of AOX therapy may be achieved to maximize the therapeutic potential of these agents.

High-fiber-diet-related metabolites improve neurodegenerative symptoms in patients with obesity with diabetes mellitus by modulating the hippocampal-hypothalamic endocrine axis

Objective

Through transcriptomic and metabolomic analyses, this study examined the role of high-fiber diet in obesity complicated by diabetes and neurodegenerative symptoms.

Method

The expression matrix of high-fiber-diet-related metabolites, blood methylation profile associated with pre-symptomatic dementia in elderly patients with type 2 diabetes mellitus (T2DM), and high-throughput single-cell sequencing data of hippocampal samples from patients with Alzheimer's disease (AD) were retrieved from the Gene Expression Omnibus (GEO) database and through a literature search. Data were analyzed using principal component analysis (PCA) after quality control and data filtering to identify different cell clusters and candidate markers. A protein-protein interaction network was mapped using the STRING database. To further investigate the interaction among high-fiber-diet-related metabolites, methylation-related DEGs related to T2DM, and single-cell marker genes related to AD, AutoDock was used for semi-flexible molecular docking.

Result

Based on GEO database data and previous studies, 24 marker genes associated with high-fiber diet, T2DM, and AD were identified. Top 10 core genes include SYNE1, ANK2, SPEG, PDZD2, KALRN, PTPRM, PTPRK, BIN1, DOCK9, and NPNT, and their functions are primarily related to autophagy. According to molecular docking analysis, acetamidobenzoic acid, the most substantially altered metabolic marker associated with a high-fiber diet, had the strongest binding affinity for SPEG.

Conclusion

By targeting the SPEG protein in the hippocampus, acetamidobenzoic acid, a metabolite associated with high-fiber diet, may improve diabetic and neurodegenerative diseases in obese people.

MnTE-2-PyP protects fibroblast mitochondria from hyperglycemia and radiation exposure

Radiation is a common anticancer therapy for prostate cancer, which transforms tumor-associated normal fibroblasts to myofibroblasts, resulting in fibrosis. Oxidative stress caused by radiation-mediated mitochondrial damage is one of the major contributors to fibrosis. As diabetics are oxidatively stressed, radiation-mediated reactive oxygen species cause severe treatment failure, treatment-related side effects, and significantly reduced survival for diabetic prostate cancer patients as compared to non-diabetic prostate cancer patients. Hyperglycemia and enhanced mitochondrial damage significantly contribute to oxidative damage and disease progression after radiation therapy among diabetic prostate cancer patients. Therefore, reduction of mitochondrial damage in normal prostate fibroblasts after radiation should improve the overall clinical state of diabetic prostate cancer patients. We previously reported that MnTE-2-PyP, a manganese porphyrin, reduces oxidative damage in irradiated hyperglycemic prostate fibroblasts by scavenging superoxide and activating NRF2. In the current study, we have investigated the potential role of MnTE-2-PyP to protect mitochondrial health in irradiated hyperglycemic prostate fibroblasts. This study revealed that hyperglycemia and radiation increased mitochondrial ROS via blocking the mitochondrial electron transport chain, altered mitochondrial dynamics, and reduced mitochondrial biogenesis. Increased mitochondrial damage preceeded an increase in myofibroblast differentiation. MnTE-2-PyP reduced myofibroblast differentiation, improved mitochondrial health by releasing the block on the mitochondrial electron transport chain, enhanced ATP production efficiency, and restored mitochondrial dynamics and metabolism in the irradiated-hyperglycemic prostate fibroblasts. Therefore, we are proposing that one of the mechanisms that MnTE-2-PyP protects prostate fibroblasts from irradiation and hyperglycemia-mediated damage is by protecting the mitochondrial health in diabetic prostate cancer patients.

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MnTE-2-PyP protects mitochondria from radiation and hyperglycemia-induced stress.

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MnTE-2-PyP reduced mitochondrial ROS by restoring the levels of OXPHOS complexes.

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MnTE-2-PyP increased the number of healthy mitochondria and enhanced ATP production efficiency.

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Mitochondrial protection by MnTE-2-PyP inhibits myofibroblast differentiation.

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MnTE-2-PyP treatment partly restores radiation-mediated metabolic changes.

Antioxidant MnTBAP does not protect adult mice from neonatal hyperoxic lung injury

BACKGROUND

Oxygen therapy and mechanical ventilation are important predisposing factors for the development of bronchopulmonary dysplasia (BPD), leading to increased morbidity and mortality in premature infants. Oxygen toxicity mediated by reactive oxygen species (ROS) may play an important part in the development of BPD. We studied the effects of MnTBAP, a catalytic antioxidant on airway responsiveness and alveolar simplification in adult mice following neonatal hyperoxia.

METHODS

Mice litters were randomized to 85 %O2 or room air (RA) on D3 for 12 days to receive either MnTBAP (10 mg/kg/d) or saline intraperitoneally. Methacholine challenge (MCC) performed at 8 and 12 weeks of age by whole-body plethysmography to assess airway reactivity. Alveolarization quantified on lung sections by radial alveolar count (RAC) and mean linear intercept (MLI). Cell counts assessed from bronchoalveolar lavage (BAL) performed at 15 weeks.

RESULTS

Mice exposed to hyperoxia and MnTBAP (OXMN) had significantly higher airway reactivity post-MCC at 8 weeks compared to RA and O2 groups. At 12 weeks, airway reactivity was higher post-MCC in both hyperoxia and OXMN groups. MnTBAP did not attenuate hyperoxia-induced airway reactivity in adult mice. Hyperoxia exposed mice demonstrated large and distended alveoli on histopathology at 2 and 15 weeks. MnTBAP did not ameliorate hyperoxia-induced lung injury as assessed by RAC/MLI. Absolute lymphocyte count was significantly higher in BAL in the hyperoxia and OXMN groups.

CONCLUSIONS

MnTBAP, a catalytic antioxidant, did not afford protection from hyperoxia-induced lung injury in adult mice.

Effects of antioxidant MnTBAP on angiogenesis in newborn mice with hyperoxic lung injury

BACKGROUND

Oxygen toxicity mediated by reactive oxygen species (ROS) plays an essential role in the development of bronchopulmonary dysplasia in premature infants. By reducing oxidative stress, antioxidants protect the immature lung. We studied the effects of MnTBAP, a catalytic antioxidant on angiogenesis and alveolar growth following neonatal hyperoxia.

METHODS

Newborn mouse litters randomized to room air (RA) or >95% O2 for 72 hours from day 4 (D4) to D7 to receive either MnTBAP (10 mg/kg/d) or saline intraperitoneally (every 24 h for three doses). Lungs harvested for angiogenic gene expression, protein expression, and histopathology post-hyperoxia exposure. Radial alveolar count (RAC), mean linear intercept (MLI) and vessel density assessed by histopathology.

RESULTS

Angiogenic gene expression was significantly lower in the hyperoxia group compared to the RA group. The protein expression for VEGF and its receptor, VEGFR1, was significantly lower following treatment with MnTBAP compared to hyperoxia alone. Expression of VEGFR2, Angiopoietin-1 and TIE2, were substantially higher in the RA groups compared to hyperoxia groups with or without MnTBAP. Hyperoxia groups demonstrated alveolar simplification. MnTBAP reduced vessel density and failed to improve alveolar growth following hyperoxia.

CONCLUSIONS

MnTBAP, a catalytic antioxidant, does not offer protection from hyperoxia-induced alveolar impairment. The lack of angiogenic upregulation by MnTBAP may contribute to alveolar simplification in newborn mice.

The Identification of Characteristic Macro- and Micronutrients and the Bioactive Components of Indonesian Local Brown Rice as a Functional Feed in Obesity Nutrition Therapy

Background:

Public interest and awareness of the use of functional food as an obesity nutrition therapy are increasing.

Objective:

This study aims to analyze the content of energy, macronutrients, minerals (magnesium, manganese, and potassium), and bioactive components (fiber, β-glucan) in Indonesian varieties of brown rice compared to white rice, to provide precise information on the nutritional content of brown rice as a functional food in obesity nutrition therapy.

Methods:

This research took the form of a laboratory analysis to identify the content of energy, macronutrients, fiber, β-glucan, magnesium, manganese, and potassium in brown rice varieties Sinta Nur. The energy content of rice was analyzed using bomb calorimetry; macronutrients were analyzed by spectrophotometry, gravimetric extraction, and acid-base titration; dietary fiber, and β-glucan were analyzed by enzymatic methods; and mineral contents were analyzed by spectrophotometry and atomic absorption spectrophotometry.

Results:

The results demonstrated that the energy and macronutrient content of brown rice are higher than white rice. However, brown rice also has dietary fiber and β-glucan contents that are 5 times higher than white rice. For the macronutrient, in brief, magnesium content was 7.7 times higher, potassium was 5.7 times higher, and manganese was 1.59 times higher within the brown rice. Cooked rice is known for lower nutritional value, but the nutritional value of Indonesian brown rice is still higher than white rice.

Conclusion:

The results of this study indicate that brown rice has nutrient content and bioactive components that allegedly contribute to higher obesity intervention than white rice.

An adiponectin-S1P axis protects against lipid induced insulin resistance and cardiomyocyte cell death via reduction of oxidative stress

BACKGROUND

Adiponectin exerts several beneficial cardiovascular effects, however their specific molecular mechanisms require additional understanding. This study investigated the mechanisms of adiponectin action in the heart during high fat diet (HFD) feeding or in palmitate (PA) treated H9c2 cardiomyoblasts.

METHODS

6-week-old male adiponectin knock out (Ad-KO) mice were fed chow or 60% HFD for 6 weeks then received saline or recombinant adiponectin (3μg/g body weight) for an additional 2 weeks. After acute insulin stimulation (4 U/kg), tissue and serum samples were collected for analysis. H9c2 cardiomyocytes were treated ±0.1 mM PA, the adiponectin receptor agonist AdipoRon, or the antioxidant MnTBAP then assays to analyze reactive oxygen species (ROS) production and cell death were conducted. To specifically determine the mechanistic role of S1P, gain and loss of function studies were conducted with adding S1P to cells or the inhibitors THI and SKI-II, respectively.

RESULTS

HFD feeding induced cardiac insulin resistance in Ad-KO mice, which was reversed following replenishment of normal circulating adiponectin levels. In addition, myocardial total triglyceride was elevated by HFD and lipidomic analysis showed increased levels of ceramides and sphingosine-1-phosphate (S1P), with only the latter being corrected by adiponectin administration. Similarly, treatment of H9C2 cardiomyoblasts with PA led to a significant increase of intracellular S1P but not in conditioned media whereas AdipoRon significantly increased S1P production and secretion from cells. AdipoRon or the antioxidant MnTBAP significantly reduced PA-induced cell death. Gain and loss of function studies suggested S1P secretion and autocrine receptor activation mediated the effect of AdipoRon to attenuate PA-induced ROS production and cell death.

CONCLUSION

Our data establish adiponectin signaling-mediated increase in S1P secretion as a mechanism via which HFD or PA induced cardiomyocyte lipotoxicity, leading to insulin resistance and cell death, is attenuated.

Mn Porphyrin-Based Redox-Active Drugs: Differential Effects as Cancer Therapeutics and Protectors of Normal Tissue Against Oxidative Injury

SIGNIFICANCE

After approximatelty three decades of research, two Mn(III) porphyrins (MnPs), MnTE-2-PyP⁵⁺ (BMX-010, AEOL10113) and MnTnBuOE-2-PyP⁵⁺ (BMX-001), have progressed to five clinical trials. In parallel, another similarly potent metal-based superoxide dismutase (SOD) mimic-Mn(II)pentaaza macrocycle, GC4419-has been tested in clinical trial on application, identical to that of MnTnBuOE-2-PyP⁵⁺-radioprotection of normal tissue in head and neck cancer patients. This clearly indicates that Mn complexes that target cellular redox environment have reached sufficient maturity for clinical applications. Recent Advances: While originally developed as SOD mimics, MnPs undergo intricate interactions with numerous redox-sensitive pathways, such as those involving nuclear factor κB (NF-κB) and nuclear factor E2-related factor 2 (Nrf2), thereby impacting cellular transcriptional activity. An increasing amount of data support the notion that MnP/H₂O₂/glutathione (GSH)-driven catalysis of S-glutathionylation of protein cysteine, associated with modification of protein function, is a major action of MnPs on molecular level.

CRITICAL ISSUES

Differential effects of MnPs on normal versus tumor cells/tissues, which support their translation into clinic, arise from differences in their accumulation and redox environment of such tissues. This in turn results in different yields of MnP-driven modifications of proteins. Thus far, direct evidence for such modification of NF-κB, mitogen-activated protein kinases (MAPK), phosphatases, Nrf2, and endogenous antioxidative defenses was provided in tumor, while indirect evidence shows the modification of NF-κB and Nrf2 translational activities by MnPs in normal tissue.

FUTURE DIRECTIONS

Studies that simultaneously explore differential effects in same animal are lacking, while they are essential for understanding of extremely intricate interactions of metal-based drugs with complex cellular networks of normal and cancer cells/tissues.

Radiation-Mediated Tumor Growth Inhibition Is Significantly Enhanced with Redox-Active Compounds That Cycle with Ascorbate

AIMS

We aim here to demonstrate that radiation (RT) enhances tumor sensitization by only those Mn complexes that are redox active and cycle with ascorbate (Asc), thereby producing H2O2 and utilizing it subsequently in protein S-glutathionylation in a glutathione peroxidase (GPx)-like manner. In turn, such compounds affect cellular redox environment, described by glutathione disulfide (GSSG)/glutathione (GSH) ratio, and tumor growth. To achieve our goal, we tested several Mn complexes of different chemical and physical properties in cellular and animal flank models of 4T1 breast cancer cell. Four other cancer cell lines were used to substantiate key findings.

RESULTS

Joint administration of cationic Mn porphyrin (MnP)-based redox active compounds, MnTE-2-PyP5+ or MnTnBuOE-2-PyP5+ with RT and Asc contributes to high H2O2 production in cancer cells and tumor, which along with high MnP accumulation in cancer cells and tumor induces the largest suppression of cell viability and tumor growth, while increasing GSSG/GSH ratio and levels of total S-glutathionylated proteins. Redox-inert MnP, MnTBAP3- and two other different types of redox-active Mn complexes (EUK-8 and M40403) were neither efficacious in the cellular nor in the animal model. Such outcome is in accordance with their inability to catalyze Asc oxidation and mimic GPx.

INNOVATION

We provided here the first evidence how structure-activity relationship between the catalytic potency and the redox properties of Mn complexes controls their ability to impact cellular redox environment and thus enhance the radiation and ascorbate-mediated tumor suppression.

CONCLUSIONS

The interplay between the accumulation of cationic MnPs and their potency as catalysts for oxidation of Asc, protein cysteines, and GSH controls the magnitude of their anticancer therapeutic effects.

A combination of Lactobacillus mali APS1 and dieting improved the efficacy of obesity treatment via manipulating gut microbiome in mice

The difficulty of long-term management has produced a high rate of failure for obesity patients. Therefore, improving the efficacy of current obesity treatment is a significant goal. We hypothesized that combining a probiotic Lactobacillus mali APS1 intervention with dieting could improve the efficacy of obesity and hepatic steatosis treatment compared to dieting alone. Mice were fed a high-fat diet for 6 weeks and then treated with: saline + normal diet and APS1 + normal diet (NDAPS1) for 3 weeks. NDAPS1 accelerated body weight loss and reduced caloric intake and fat accumulation. The fecal microbiome showed that accelerating weight loss by NDAPS1 resulted in restoring intestinal microbiota toward a pre-obese state, with alteration of specific changes in the obesity-associated bacteria. APS1 manipulated the gut microbiome's obesity-associated metabolites, followed by regulation of lipid metabolism, enhancement of energy expenditure and inhibition of appetite. The specific hepatic metabolites induced by the APS1-manipulated gut microbiome also contributed to the amelioration of hepatic steatosis. Our results highlighted a possible microbiome and metabolome that contributed to accelerating weight loss following treatment with a combination of APS1 and dieting and suggested that probiotics could serve as a potential therapy for modulating physiological function and downstream of the microbiota.

The Essential Element Manganese, Oxidative Stress, and Metabolic Diseases: Links and Interactions

Manganese (Mn) is an essential element that is involved in the synthesis and activation of many enzymes and in the regulation of the metabolism of glucose and lipids in humans. In addition, Mn is one of the required components for Mn superoxide dismutase (MnSOD) that is mainly responsible for scavenging reactive oxygen species (ROS) in mitochondrial oxidative stress. Both Mn deficiency and intoxication are associated with adverse metabolic and neuropsychiatric effects. Over the past few decades, the prevalence of metabolic diseases, including type 2 diabetes mellitus (T2MD), obesity, insulin resistance, atherosclerosis, hyperlipidemia, nonalcoholic fatty liver disease (NAFLD), and hepatic steatosis, has increased dramatically. Previous studies have found that ROS generation, oxidative stress, and inflammation are critical for the pathogenesis of metabolic diseases. In addition, deficiency in dietary Mn as well as excessive Mn exposure could increase ROS generation and result in further oxidative stress. However, the relationship between Mn and metabolic diseases is not clear. In this review, we provide insights into the role Mn plays in the prevention and development of metabolic diseases.

Treatment with a Catalytic Superoxide Dismutase (SOD) Mimetic Improves Liver Steatosis, Insulin Sensitivity, and Inflammation in Obesity-Induced Type 2 Diabetes

Oxidative stress and persistent inflammation are exaggerated through chronic over-nutrition and a sedentary lifestyle, resulting in insulin resistance. In type 2 diabetes (T2D), impaired insulin signaling leads to hyperglycemia and long-term complications, including metabolic liver dysfunction, resulting in non-alcoholic fatty liver disease (NAFLD). The manganese metalloporphyrin superoxide dismustase (SOD) mimetic, manganese (III) meso-tetrakis (N-ethylpyridinium-2-yl) porphyrin (MnP), is an oxidoreductase known to scavenge reactive oxygen species (ROS) and decrease pro-inflammatory cytokine production, by inhibiting nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation. We hypothesized that targeting oxidative stress-induced inflammation with MnP would assuage liver complications and enhance insulin sensitivity and glucose tolerance in a high-fat diet (HFD)-induced mouse model of T2D. During 12 weeks of feeding, we saw significant improvements in weight, hepatic steatosis, and biomarkers of liver dysfunction with redox modulation by MnP treatment in HFD-fed mice. Additionally, MnP treatment improved insulin sensitivity and glucose tolerance, while reducing serum insulin and leptin levels. We attribute these effects to redox modulation and inhibition of hepatic NF-κB activation, resulting in diminished ROS and pro-inflammatory cytokine production. This study highlights the importance of controlling oxidative stress and secondary inflammation in obesity-mediated insulin resistance and T2D. Our data confirm the role of NF-κB-mediated inflammation in the development of T2D, and demonstrate the efficacy of MnP in preventing the progression to disease by specifically improving liver pathology and hepatic insulin resistance in obesity.

Pharmacological Reconditioning of Marginal Donor Rat Lungs Using Inhibitors of Peroxynitrite and Poly (ADP-ribose) Polymerase During Ex Vivo Lung Perfusion

BACKGROUND

Donor lungs obtained after prolonged warm ischemia (WI) may be unsuitable for transplantation due to the risk of reperfusion injury, but could be reconditioned using ex-vivo lung perfusion (EVLP). Key processes of reperfusion injury include the formation of reactive oxygen species (ROS)/nitrogen species (RNS) and the activation of poly(adenosine diphosphate-ribose) polymerase (PARP). We explored whether rat lungs obtained after WI could be reconditioned during EVLP using the ROS/RNS scavenger Mn(III)-tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) or the PARP inhibitor 3-aminobenzamide (3-AB).

METHODS

Rat lungs obtained after 3 hours cold ischemia (CI group, control), or 1 hour WI plus 2 hours CI (WI group) were placed in an EVLP circuit for normothermic perfusion for 3 hours. Lungs retrieved after WI were treated or not with 3-AB (1 mg/mL) or MnTBAP (0.3 mg/mL), added to the perfusate. Measurements included physiological variables (lung compliance, vascular resistance, oxygenation capacity), lung weight gain, levels of proteins, lactate dehydrogenase, protein carbonyl (marker of ROS), 3-nitrotyrosine (marker of RNS), poly(adenosine diphosphate-ribose) (PAR, marker of PARP activation) and IL-6, in the bronchoalveolar lavage or the lung tissue, and histology.

RESULTS

In comparison to the CI group, the lungs from the WI group displayed higher protein carbonyls, 3-nitrotyrosine, PAR, lactate dehydrogenase and proteins in bronchoalveolar lavage, lung weight gain, perivascular edema, as well as reduced static compliance, but similar oxygenation. All these alterations were markedly attenuated by 3-AB and MnTBAP.

CONCLUSIONS

After EVLP, lungs obtained after WI exhibit oxidative stress, PARP activation, and tissue injury, which are suppressed by pharmacological inhibitors of ROS/RNS and PARP.