Pioglitazone stimulates AMP-activated protein kinase signalling and increases the expression of genes involved in adiponectin signalling, mitochondrial function and fat oxidation in human skeletal muscle in vivo: a randomised trial

M1/M2 macrophage-targeted nanotechnology and PROTAC for the treatment of atherosclerosis

Macrophages play key roles in atherosclerosis progression, and an imbalance in M1/M2 macrophages leads to unstable plaques; therefore, M1/M2 macrophage polarization-targeted treatments may serve as a new approach in the treatment of atherosclerosis. At present, there is little research on M1/M2 macrophage polarization-targeted nanotechnology. Proteolysis-targeting chimera (PROTAC) technology, a targeted protein degradation technology, mediates the degradation of target proteins and has been widely promoted in preclinical and clinical applications as a novel therapeutic modality. This review summarizes the recent studies on M1/M2 macrophage polarization-targeted nanotechnology, focusing on the mechanism and advantages of PROTACs in M1/M2 macrophage polarization as a new approach for the treatment of atherosclerosis.

Efficacy and Safety of Pioglitazone Add-on in Patients with Type 2 Diabetes Mellitus Inadequately Controlled with Metformin and Dapagliflozin: A Multicenter, Randomized, Double-blind, and Placebo-Controlled Study

PURPOSE

The purpose of this study was to determine the efficacy and safety profile of pioglitazone compared with placebo (PBO) in patients with type 2 diabetes (T2D) inadequately controlled with metformin and dapagliflozin.

METHODS

In this prospective, multicenter, randomized, double-blind, PBO-controlled trial, 366 patients with T2D who did not meet glycemic targets (7.0% ≤ glycosylated hemoglobin [HbA1c] ≤ 10.5%), despite treatment with metformin ≥1000 mg and dapagliflozin 10 mg, received either a PBO, 15 mg of pioglitazone daily (PIO15), or 30 mg of pioglitazone daily (PIO30). The primary end point was the mean change in HbA1c from baseline at 24 weeks across the groups.

FINDINGS

For the 366 participants (PBO, n = 124; PIO15, n = 118; PIO30, n = 124), the mean age was 55.6 years and mean duration of diabetes was 8.7 years, with a baseline HbA1c of 7.9%. After 24 weeks, HbA1c reduced significantly in the PIO15 and PIO30 groups from baseline, with intergroup differences of -0.38% and -0.83%, respectively, compared with the PBO group. The proportion of patients with HbA1c levels <7% was significantly higher in the PIO15 and PIO30 groups than in the PBO group. The adverse event rates did not significantly differ across the groups, indicating favorable safety profiles for triple combination therapy using metformin, dapagliflozin, and pioglitazone.

IMPLICATIONS

The addition of pioglitazone as a third oral antidiabetic medication is an appropriate option for patients with T2D inadequately controlled with metformin and dapagliflozin based on the resulting significant efficacy in glycemic control and favorable safety profile.

CLINICALTRIALS

gov identifier: NCT04885712.

Pioglitazone does not enhance exogenous glucose oxidation or metabolic clearance rate during aerobic exercise in men under acute high-altitude exposure

Insulin insensitivity decreases exogenous glucose oxidation and metabolic clearance rate (MCR) during aerobic exercise in unacclimatized lowlanders at high altitude (HA). Whether use of an oral insulin sensitizer before acute HA exposure enhances exogenous glucose oxidation is unclear. This study investigated the impact of pioglitazone (PIO) on exogenous glucose oxidation and glucose turnover compared with placebo (PLA) during aerobic exercise at HA. With the use of a randomized crossover design, native lowlanders (n = 7 males, means ± SD, age: 23 ± 6 yr, body mass: 84 ± 11 kg) consumed 145 g (1.8 g/min) of glucose while performing 80 min of steady-state (1.43 ± 0.16 V̇o2 L/min) treadmill exercise at HA (460 mmHg; [Formula: see text] 96.6 mmHg) following short-term (5 days) use of PIO (15 mg oral dose per day) or PLA (microcrystalline cellulose pill). Substrate oxidation and glucose turnover were determined using indirect calorimetry and stable isotopes ([13C]glucose and 6,6-[2H2]glucose). Exogenous glucose oxidation was not different between PIO (0.31 ± 0.03 g/min) and PLA (0.32 ± 0.09 g/min). Total carbohydrate oxidation (PIO: 1.65 ± 0.22 g/min, PLA: 1.68 ± 0.32 g/min) or fat oxidation (PIO: 0.10 ± 0.0.08 g/min, PLA: 0.09 ± 0.07 g/min) was not different between treatments. There was no treatment effect on glucose rate of appearance (PIO: 2.46 ± 0.27, PLA: 2.43 ± 0.27 mg/kg/min), disappearance (PIO: 2.19 ± 0.17, PLA: 2.20 ± 0.22 mg/kg/min), or MCR (PIO: 1.63 ± 0.37, PLA: 1.73 ± 0.40 mL/kg/min). Results from this study indicate that PIO is not an effective intervention to enhance exogenous glucose oxidation or MCR during acute HA exposure. Lack of effect with PIO suggests that the etiology of glucose metabolism dysregulation during acute HA exposure may not result from insulin resistance in peripheral tissues.NEW & NOTEWORTHY Short-term (5 days) use of the oral insulin sensitizer pioglitazone does not alter circulating glucose or insulin responses to enhance exogenous glucose oxidation during steady-state aerobic exercise in young healthy men under simulated acute (8 h) high-altitude (460 mmHg) conditions. These results indicate that dysregulations in glucose metabolism in native lowlanders sojourning at high altitude may not be due to insulin resistance at peripheral tissue.

Mitochondria: A Potential Rejuvenation Tool against Aging

Aging is a complex physiological process encompassing both physical and cognitive decline over time. This intricate process is governed by a multitude of hallmarks and pathways, which collectively contribute to the emergence of numerous age-related diseases. In response to the remarkable increase in human life expectancy, there has been a substantial rise in research focusing on the development of anti-aging therapies and pharmacological interventions. Mitochondrial dysfunction, a critical factor in the aging process, significantly impacts overall cellular health. In this extensive review, we will explore the contemporary landscape of anti-aging strategies, placing particular emphasis on the promising potential of mitotherapy as a ground-breaking approach to counteract the aging process. Moreover, we will investigate the successful application of mitochondrial transplantation in both animal models and clinical trials, emphasizing its translational potential. Finally, we will discuss the inherent challenges and future possibilities of mitotherapy within the realm of aging research and intervention.

Immunomodulation through Nutrition Should Be a Key Trend in Type 2 Diabetes Treatment

An organism's ability to function properly depends not solely on its diet but also on the intake of nutrients and non-nutritive bioactive compounds that exert immunomodulatory effects. This principle applies both to healthy individuals and, in particular, to those with concomitant chronic conditions, such as type 2 diabetes. However, the current food industry and the widespread use of highly processed foods often lead to nutritional deficiencies. Numerous studies have confirmed the occurrence of immune system dysfunction in patients with type 2 diabetes. This article elucidates the impact of specific nutrients on the immune system function, which maintains homeostasis of the organism, with a particular emphasis on type 2 diabetes. The role of macronutrients, micronutrients, vitamins, and selected substances, such as omega-3 fatty acids, coenzyme Q10, and alpha-lipoic acid, was taken into consideration, which outlined the minimum range of tests that ought to be performed on patients in order to either directly or indirectly determine the severity of malnutrition in this group of patients.

The Safety and Efficacy of Combining Saxagliptin and Pioglitazone Therapy in Streptozocin-Induced Diabetic Rats

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a chronic progressive disease due to insulin resistance. Oxidative stress complicates the etiology of T2DM. Saxagliptin is a selective dipeptidyl peptidase-4 (DPP-4) inhibitor, while Pioglitazone is a thiazolidinedione insulin sensitizer. This study aimed to assess the effect of Saxagliptin and Pioglitazone monotherapy and combination therapy on the biochemical and biological parameters in streptozotocin (STZ)-induced diabetic rats.

METHODS

The study included thirty-five male albino rats. Diabetes mellitus was induced by intraperitoneal STZ injection (35 mg/kg). For a 1-month duration, rats were divided into five groups. Glucose homeostasis traits, lipid profiles, kidney functions, liver enzymes, and oxidative stress markers were measured. Gene expression of miRNA-29a, phosphoenolpyruvate carboxykinase (PEPCK), phosphoinositide-3-kinase (PI3K), and interleukin 1 beta (IL-1β) was assessed using qRT-PCR.

RESULTS

At a 1-month treatment duration, combination therapy improves oxidative stress markers more than either drug alone. The combination therapy had significantly higher levels of SOD, catalase, and GSH and lower levels of MDA compared to the monotherapy. Additionally, the diabetic group showed a significant increase in the expression levels of miRNA-29a, PEPCK, and IL-1β and a significant decrease in PI3K compared to the normal control group. However, combination therapy of Saxagliptin and Pioglitazone was more effective than either Saxagliptin or Pioglitazone alone in reversing these results, especially for PEPCK and IL-1β.

CONCLUSIONS

Our findings revealed that combining Saxagliptin and Pioglitazone improves glycemic control and genetic and epigenetic expression profiles, which play an essential regulatory role in normal metabolism.

Current Nutritional and Pharmacological Approaches for Attenuating Sarcopenia

Sarcopenia is characterized by a gradual slowing of movement due to loss of muscle mass and quality, decreased power and strength, increased risk of injury from falls, and often weakness. This review will focus on recent research trends in nutritional and pharmacological approaches to controlling sarcopenia. Because nutritional studies in humans are fairly limited, this paper includes many results from nutritional studies in mammals. The combination of resistance training with supplements containing amino acids is the gold standard for preventing sarcopenia. Amino acid (HMB) supplementation alone has no significant effect on muscle strength or muscle mass in sarcopenia, but the combination of HMB and exercise (whole body vibration stimulation) is likely to be effective. Tea catechins, soy isoflavones, and ursolic acid are interesting candidates for reducing sarcopenia, but both more detailed basic research on this treatment and clinical studies in humans are needed. Vitamin D supplementation has been shown not to improve sarcopenia in elderly individuals who are not vitamin D-deficient. Myostatin inhibitory drugs have been tried in many neuromuscular diseases, but increases in muscle mass and strength are less likely to be expected. Validation of myostatin inhibitory antibodies in patients with sarcopenia has been positive, but excessive expectations are not warranted.

Fundamental Neurochemistry Review: Microglial immunometabolism in traumatic brain injury

Traumatic brain injury (TBI) is a devastating neurological disorder caused by a physical impact to the brain that promotes diffuse damage and chronic neurodegeneration. Key mechanisms believed to support secondary brain injury include mitochondrial dysfunction and chronic neuroinflammation. Microglia and brain-infiltrating macrophages are responsible for neuroinflammatory cytokine and reactive oxygen species (ROS) production after TBI. Their production is associated with loss of homeostatic microglial functions such as immunosurveillance, phagocytosis, and immune resolution. Beyond providing energy support, mitochondrial metabolic pathways reprogram the pro- and anti-inflammatory machinery in immune cells, providing a critical immunometabolic axis capable of regulating immunologic response to noxious stimuli. In the brain, the capacity to adapt to different environmental stimuli derives, in part, from microglia's ability to recognize and respond to changes in extracellular and intracellular metabolite levels. This capacity is met by an equally plastic metabolism, capable of altering immune function. Microglial pro-inflammatory activation is associated with decreased mitochondrial respiration, whereas anti-inflammatory microglial polarization is supported by increased oxidative metabolism. These metabolic adaptations contribute to neuroimmune responses, placing mitochondria as a central regulator of post-traumatic neuroinflammation. Although it is established that profound neurometabolic changes occur following TBI, key questions related to metabolic shifts in microglia remain unresolved. These include (a) the nature of microglial mitochondrial dysfunction after TBI, (b) the hierarchical positions of different metabolic pathways such as glycolysis, pentose phosphate pathway, glutaminolysis, and lipid oxidation during secondary injury and recovery, and (c) how immunometabolism alters microglial phenotypes, culminating in chronic non-resolving neuroinflammation. In this basic neurochemistry review article, we describe the contributions of immunometabolism to TBI, detail primary evidence of mitochondrial dysfunction and metabolic impairments in microglia and macrophages, discuss how major metabolic pathways contribute to post-traumatic neuroinflammation, and set out future directions toward advancing immunometabolic phenotyping in TBI.

Mitochondria in health, disease, and aging

Mitochondria are well known as organelles responsible for the maintenance of cellular bioenergetics through the production of ATP. Although oxidative phosphorylation may be their most important function, mitochondria are also integral for the synthesis of metabolic precursors, calcium regulation, the production of reactive oxygen species, immune signaling, and apoptosis. Considering the breadth of their responsibilities, mitochondria are fundamental for cellular metabolism and homeostasis. Appreciating this significance, translational medicine has begun to investigate how mitochondrial dysfunction can represent a harbinger of disease. In this review, we provide a detailed overview of mitochondrial metabolism, cellular bioenergetics, mitochondrial dynamics, autophagy, mitochondrial damage-associated molecular patterns, mitochondria-mediated cell death pathways, and how mitochondrial dysfunction at any of these levels is associated with disease pathogenesis. Mitochondria-dependent pathways may thereby represent an attractive therapeutic target for ameliorating human disease.

Repurposing Drugs for Diabetes Mellitus as Potential Pharmacological Treatments for Sarcopenia - A Narrative Review

Sarcopenia, the age-related loss of muscle strength and mass or quality, is a common condition with major adverse consequences. Although the pathophysiology is incompletely understood, there are common mechanisms between sarcopenia and the phenomenon of accelerated ageing seen in diabetes mellitus. Drugs currently used to treat type 2 diabetes mellitus may have mechanisms of action that are relevant to the prevention and treatment of sarcopenia, for those with type 2 diabetes and those without diabetes. This review summarises shared pathophysiology between sarcopenia and diabetes mellitus, including the effects of advanced glycation end products, mitochondrial dysfunction, chronic inflammation and changes to the insulin signalling pathway. Cellular and animal models have generated intriguing, albeit mixed, evidence that supports possible beneficial effects on skeletal muscle function for some classes of drugs used to treat diabetes, including metformin and SGLT2 inhibitors. Most human observational and intervention evidence for the effects of these drugs has been derived from populations with type 2 diabetes mellitus, and there is a need for intervention studies for older people with, and at risk of, sarcopenia to further investigate the balance of benefit and risk in these target populations. Not all diabetes treatments will be safe to use in those without diabetes because of variable side effects across classes. However, some agents [including glucagon-like peptide (GLP)-1 receptor agonists and SGLT2 inhibitors] have already demonstrated benefits in populations without diabetes, and it is these agents, along with metformin, that hold out the most promise for further investigation in sarcopenia.

Pioglitazone reduces epicardial fat and improves diastolic function in patients with type 2 diabetes

AIMS

To examine the effect of pioglitazone on epicardial (EAT) and paracardial adipose tissue (PAT) and measures of diastolic function and insulin sensitivity in patients with type 2 diabetes mellitus (T2DM).

METHODS

Twelve patients with T2DM without clinically manifest cardiovascular disease and 12 subjects with normal glucose tolerance (NGT) underwent cardiac magnetic resonance imaging to quantitate EAT and PAT and diastolic function before and after pioglitazone treatment for 24 weeks. Whole-body insulin sensitivity was measured with a euglycaemic insulin clamp and the Matsuda Index (oral glucose tolerance test).

RESULTS

Pioglitazone reduced glycated haemoglobin by 0.9% (P < 0.05), increased HDL cholesterol by 7% (P < 0.05), reduced triacylglycerol by 42% (P < 0.01) and increased whole-body insulin-stimulated glucose uptake by 71% (P < 0.01) and Matsuda Index by 100% (P < 0.01). In patients with T2DM, EAT (P < 0.01) and PAT (P < 0.01) areas were greater compared with subjects with NGT, and decreased by 9% (P = 0.03) and 9% (P = 0.09), respectively, after pioglitazone treatment. Transmitral E/A flow rate and peak left ventricular flow rate (PLVFR) were reduced in T2DM versus NGT (P < 0.01) and increased following pioglitazone treatment (P < 0.01-0.05). At baseline normalized PLVFR inversely correlated with EAT (r = -0.45, P = 0.03) but not PAT (r = -0.29, P = 0.16). E/A was significantly and inversely correlated with EAT (r = -0.55, P = 0.006) and PAT (r = -0.40, P = 0.05). EAT and PAT were inversely correlated with whole-body insulin-stimulated glucose uptake (r = -0.68, P < 0.001) and with Matsuda Index (r = 0.99, P < 0.002).

CONCLUSION

Pioglitazone reduced EAT and PAT areas and improved left ventricular (LV) diastolic function in T2DM. EAT and PAT are inversely correlated (PAT less strongly) with LV diastolic function and both EAT and PAT are inversely correlated with measures of insulin sensitivity.

Can pioglitazone be used for optimization of nutrition in critical illness? A systematic review

BACKGROUND

Skeletal muscle wasting is a determinant of physical disability in survivors of critical illness. Intramuscular bioenergetic failure, altered substrate metabolim, and inflammation are likely underpinning mechanisms. We examined the effect of pioglitazone, a peroxisome proliferator-activated receptor γ agonist, on muscle-related outcomes in adults.

METHODS

We included randomized controlled trials in which pioglitazone was administered (no dose/dosage restrictions) and muscle-related outcomes were reported. We searched MEDLINE, CENTRAL, EMBASE, CINAHL, and trial registries. Risk of bias was assessed using RoB 2. Primary outcomes were physical function and symptoms, muscle mass and function, or body composition and muscular compositional change. Secondary outcomes included muscle insulin sensitivity, mitochondrial effects, and intramuscular inflammation.

RESULTS

Fourteen studies over 19 publications (n = 474 patients) were included. Lean body mass was unaffected in three studies (n = 126) and increased by 1.8-1.92 kg in two studies (P = 0.02 and 0.003, respectively; n = 48). Pioglitazone was associated with increased peripheral insulin sensitivity (+23%-72%, standardized mean difference of 0.97 from trial start point to end point [95% CI, 0.36-1.58; n = 213]). Treatment reduced intramuscular tumor necrosis factor-α (TNF-α) levels (-30%; P = 0.02; n = 29), with mixed effects on serum TNF-α and intramyocellular lipid concentrations. Treatment increased intramuscular markers of adenosine triphosphate (ATP) biosynthesis (ATP5A [+33%, P ≤ 0.05], ETFA [+60%, P ≤ 0.05], and CX6B1 [+ 33%, P = 0.01] [n = 24]), PGC1α and PGC1β messenger RNA expression (P < 0.05; n = 26), and AMPK phosphorylation (+38%, P < 0.05; n = 26). These data have low-quality evidence profiles owing to risk of bias.

CONCLUSIONS

Pioglitazone therapy increases skeletal muscle insulin sensitivity and can decrease intramuscular inflammation.

Molecular Mechanisms Through Which Cannabidiol May Affect Skeletal Muscle Metabolism, Inflammation, Tissue Regeneration, and Anabolism: A Narrative Review

Background: Cannabidiol (CBD), a nonintoxicating constituent of the cannabis plant, recently gained a lot of interest among athletes, since it is no longer considered as a prohibited substance by the World Anti-Doping Agency. The increasing prevalence of CBD use among athletes is driven by a perceived improvement in muscle recovery and a reduction in pain. However, compelling evidence from intervention studies is lacking and the precise mechanisms through which CBD may improve muscle recovery remain unknown. This highlights the need for more scientific studies and an evidence-based background. In the current review, the state-of-the-art knowledge on the effects of CBD on skeletal muscle tissue is summarized with special emphasis on the underlying mechanisms and molecular targets. More specifically, the large variety of receptor families that are believed to be involved in CBD's physiological effects are discussed. Furthermore, in vivo and in vitro studies that investigated the actual effects of CBD on skeletal muscle metabolism, inflammation, tissue regeneration, and anabolism are summarized, together with the functional effects of CBD supplementation on muscle recovery in human intervention trials. Overall, CBD was effective to increase the expression of metabolic regulators in muscle of obese mice (e.g., Akt, glycogen synthase kinase-3). CBD treatment in rodents reduced muscle inflammation following eccentric exercise (i.e., nuclear factor kappa B [NF-κB]), in a model of muscle dystrophy (e.g., interleukin-6, tumor necrosis factor alpha) and of obesity (e.g., COX-2, NF-κB). In addition, CBD did not affect in vitro or in vivo muscle anabolism, but improved satellite cell differentiation in dystrophic muscle. In humans, there are some indications that CBD supplementation improved muscle recovery (e.g., creatine kinase) and performance (e.g., squat performance). However, CBD doses were highly variable (between 16.7 and 150 mg) and there are some methodological concerns that should be considered. Conclusion: CBD has the prospective to become an adequate supplement that may improve muscle recovery. However, this research domain is still in its infancy and future studies addressing the molecular and functional effects of CBD in response to exercise are required to further elucidate the ergogenic potential of CBD.

Effect of Insulin and Pioglitazone on Protein Phosphatase 2A Interaction Partners in Primary Human Skeletal Muscle Cells Derived from Obese Insulin-Resistant Participants

Skeletal muscle insulin resistance is a major contributor to type-2 diabetes (T2D). Pioglitazone is a potent insulin sensitizer of peripheral tissues by targeting peroxisome proliferator-activated receptor gamma. Pioglitazone has been reported to protect skeletal muscle cells from lipotoxicity by promoting fatty acid mobilization and insulin signaling. However, it is unclear whether pioglitazone increases insulin sensitivity through changes in protein-protein interactions involving protein phosphatase 2A (PP2A). PP2A regulates various cell signaling pathways such as insulin signaling. Interaction of the catalytic subunit of PP2A (PP2Ac) with protein partners is required for PP2A specificity and activity. Little is known about PP2Ac partners in primary human skeletal muscle cells derived from lean insulin-sensitive (Lean) and obese insulin-resistant (OIR) participants. We utilized a proteomics method to identify PP2Ac interaction partners in skeletal muscle cells derived from Lean and OIR participants, with or without insulin and pioglitazone treatments. In this study, 216 PP2Ac interaction partners were identified. Furthermore, 26 PP2Ac partners exhibited significant differences in their interaction with PP2Ac upon insulin treatments between the two groups. Multiple pathways and molecular functions are significantly enriched for these 26 interaction partners, such as nonsense-mediated decay, metabolism of RNA, RNA binding, and protein binding. Interestingly, pioglitazone restored some of these abnormalities. These results provide differential PP2Ac complexes in Lean and OIR in response to insulin/pioglitazone, which may help understand molecular mechanisms underpinning insulin resistance and the insulin-sensitizing effects of pioglitazone treatments, providing multiple targets in various pathways to reverse insulin resistance and prevent and/or manage T2D with less drug side effects.

AMPK: An odyssey of a metabolic regulator, a tumor suppressor, and now a contextual oncogene

Metabolic reprogramming is a unique but complex biochemical adaptation that allows solid tumors to tolerate various stresses that challenge cancer cells for survival. Under conditions of metabolic stress, mammalian cells employ adenosine monophosphate (AMP)-activated protein kinase (AMPK) to regulate energy homeostasis by controlling cellular metabolism. AMPK has been described as a cellular energy sensor that communicates with various metabolic pathways and networks to maintain energy balance. Earlier studies characterized AMPK as a tumor suppressor in the context of cancer. Later, a paradigm shift occurred in support of the oncogenic nature of AMPK, considering it a contextual oncogene. In support of this, various cellular and mouse models of tumorigenesis and clinicopathological studies demonstrated increased AMPK activity in various cancers. This review will describe AMPK's pro-tumorigenic activity in various malignancies and explain the rationale and context for using AMPK inhibitors in combination with anti-metabolite drugs to treat AMPK-driven cancers.

Metabolic changes in aging humans: current evidence and therapeutic strategies

Aging and metabolism are inextricably linked, and many age-related changes in body composition, including increased central adiposity and sarcopenia, have underpinnings in fundamental aging processes. These age-related changes are further exacerbated by a sedentary lifestyle and can be in part prevented by maintenance of activity with aging. Here we explore the age-related changes seen in individual metabolic tissues - adipose, muscle, and liver - as well as globally in older adults. We also discuss the available evidence for therapeutic interventions such as caloric restriction, resistance training, and senolytic and senomorphic drugs to maintain healthy metabolism with aging, focusing on data from human studies.

The role of protein kinases as key drivers of metabolic dysfunction-associated fatty liver disease progression: New insights and future directions

Metabolic dysfunction-associated fatty liver disease (MAFLD), proposed in 2020 is a novel term for non-alcoholic fatty liver disease (NAFLD) which was coined for the first time in 1980. It is a leading cause of the most chronic liver disease and hepatic failure all over the world, and unfortunately, with no licensed drugs for treatment yet. The progress of the disease is driven by the triggered inflammatory process, oxidative stress, and insulin resistance in many pathways, starting with simple hepatic steatosis to non-alcoholic steatohepatitis, fibrosis, cirrhosis, and liver cancer. Protein kinases (PKs), such as MAPK, ErbB, PKC, PI3K/Akt, and mTOR, govern most of the pathological pathways by acting on various downstream key points in MAFLD and regulating both hepatic gluco- lipo-neogenesis and inflammation. Therefore, modulating the function of those potential protein kinases that are effectively involved in MAFLD might be a promising therapeutic approach for tackling this disease. In the current review, we have discussed the key role of protein kinases in the pathogenesis of MAFLD and performed a protein-protein interaction (PPI) network among the main proteins of each kinase pathway with MAFLD-related proteins to predict the most likely targets of the PKs in MAFLD. Moreover, we have reported the experimental, pre-clinical, and clinical data for the most recent investigated molecules that are activating p38-MAPK and AMPK proteins and inhibiting the other PKs to improve MAFLD condition by regulating oxidation and inflammation signalling.

Endoplasmic reticulum stress increases LECT2 expression via ATF4

Non-alcoholic fatty liver disease (NAFLD) is frequently associated with obesity, insulin resistance, and endoplasmic reticulum (ER) stress. Elevated circulating levels of the hepatokine leukocyte cell-derived chemotaxin-2 (LECT2) have also been noted in NAFLD; however, the mechanism underlying this association is unclear. To investigate a possible link between ER stress/unfolded protein response (UPR) signaling and LECT2 secretion, HepG2 cells were incubated with ER stress inducers with or without an ER stress-reducing chemical chaperone. Additionally, UPR pathway genes were knocked down and overexpressed, and a ChIP assay was performed. In diet-induced obese mice, hepatic expression of LECT2 and activating transcription factor 4 (ATF4) was measured. In HepG2 cells, LECT2 expression was increased by ER stressors, an effect blocked by the chemical chaperone. Among UPR pathway proteins, only knockdown of ATF4 suppressed ER stress-induced LECT2 expression, while overexpression of ATF4 enhanced LECT2 expression. The ChIP assay revealed that ATF4 binds to three putative binding sites on the LECT2 promoter and binding is promoted by an ER stress inducer. In steatotic livers of obese mice, LECT2 and ATF4 expression was concomitantly elevated. Our data indicate that activation of ER stress/UPR signaling induces LECT2 expression in steatotic liver; specifically, ATF4 appears to mediate upregulation of LECT2 transcription.

Transcriptional Analysis of Nuclear-Encoded Mitochondrial Genes in Eight Neurodegenerative Disorders: The Analysis of Seven Diseases in Reference to Friedreich’s Ataxia

Neurodegenerative diseases (NDDs) are challenging to understand, diagnose, and treat. Revealing the genomic and transcriptomic changes in NDDs contributes greatly to the understanding of the diseases, their causes, and development. Moreover, it enables more precise genetic diagnosis and novel drug target identification that could potentially treat the diseases or at least ease the symptoms. In this study, we analyzed the transcriptional changes of nuclear-encoded mitochondrial (NEM) genes in eight NDDs to specifically address the association of these genes with the diseases. Previous studies show strong links between defects in NEM genes and neurodegeneration, yet connecting specific genes with NDDs is not well studied. Friedreich’s ataxia (FRDA) is an NDD that cannot be treated effectively; therefore, we focused first on FRDA and compared the outcome with seven other NDDs, including Alzheimer’s disease, amyotrophic lateral sclerosis, Creutzfeldt–Jakob disease, frontotemporal dementia, Huntington’s disease, multiple sclerosis, and Parkinson’s disease. First, weighted correlation network analysis was performed on an FRDA RNA-Seq data set, focusing only on NEM genes. We then carried out differential gene expression analysis and pathway enrichment analysis to pinpoint differentially expressed genes that are potentially associated with one or more of the analyzed NDDs. Our findings propose a strong link between NEM genes and NDDs and suggest that our identified candidate genes can be potentially used as diagnostic markers and therapeutic targets.

The Regulatory Roles of PPARs in Skeletal Muscle Fuel Metabolism and Inflammation: Impact of PPAR Agonism on Muscle in Chronic Disease, Contraction and Sepsis

The peroxisome proliferator-activated receptor (PPAR) family of transcription factors has been demonstrated to play critical roles in regulating fuel selection, energy expenditure and inflammation in skeletal muscle and other tissues. Activation of PPARs, through endogenous fatty acids and fatty acid metabolites or synthetic compounds, has been demonstrated to have lipid-lowering and anti-diabetic actions. This review will aim to provide a comprehensive overview of the functions of PPARs in energy homeostasis, with a focus on the impacts of PPAR agonism on muscle metabolism and function. The dysregulation of energy homeostasis in skeletal muscle is a frequent underlying characteristic of inflammation-related conditions such as sepsis. However, the potential benefits of PPAR agonism on skeletal muscle protein and fuel metabolism under these conditions remains under-investigated and is an area of research opportunity. Thus, the effects of PPARγ agonism on muscle inflammation and protein and carbohydrate metabolism will be highlighted, particularly with its potential relevance in sepsis-related metabolic dysfunction. The impact of PPARδ agonism on muscle mitochondrial function, substrate metabolism and contractile function will also be described.

Hypoglycemic activity of puerarin through modulation of oxidative stress and mitochondrial function via AMPK

Hyperglycemia is the dominant phenotype of diabetes and the main contributor of diabetic complications. Puerarin is widely used in cardiovascular diseases and diabetic vascular complications. However, little is known about its direct effects on diabetes. The aim of our study is to investigate its antidiabetic effect in vivo and in vitro, and explore the underlying mechanism. We used type I diabetic mice induced by streptozotocin to observe the effects of puerarin on glucose metabolism. In addition, oxidative stress and hepatic mitochondrial respiratory activity were evaluated in type I diabetic mice. In vitro, glucose consumption in HepG2 cells was assayed along with the qPCR detection of glucogenesis genes expression. Moreover, ATP production was examined and phosphorylation of AMPK was determined using Western blot. Finally, the molecular docking was performed to predict the potential interaction of puerarin with AMPK utilizing program LibDock of Discovery Studio 2018 software. The results showed that puerarin improved HepG2 glucose consumption and upregulated the glucogenesis related genes expression. Also, puerarin lowered fasting and fed blood glucose with improvement of glucose tolerance in type I diabetic mice. Further mechanism investigation showed that puerarin suppressed oxidative stress and improved hepatic mitochondrial respiratory function with enhancing ATP production and activating phosphorylation of AMPK. Docking study showed that puerarin interacted with AMPK activate site and enhancing phosphorylation. Taken together, these findings indicated that puerarin exhibited the hypoglycemic effect through attenuating oxidative stress and improving mitochondrial function via AMPK regulation, which may serve as a potential therapeutic option for diabetes treatment.

The Impact of Glucose-Lowering Drugs on Sarcopenia in Type 2 Diabetes: Current Evidence and Underlying Mechanisms

The age-related decrease in skeletal muscle mass together with the loss of muscle power and function is defined sarcopenia. Mounting evidence suggests that the prevalence of sarcopenia is higher in patients with type 2 diabetes mellitus (T2DM), and different mechanisms may be responsible for this association such as impaired insulin sensitivity, chronic hyperglycemia, advanced glycosylation end products, subclinical inflammation, microvascular and macrovascular complications. Glucose-lowering drugs prescribed for patients with T2DM might impact on these mechanisms leading to harmful or beneficial effect on skeletal muscle. Importantly, beyond their glucose-lowering effects, glucose-lowering drugs may affect per se the equilibrium between protein anabolism and catabolism through several mechanisms involved in skeletal muscle physiology, contributing to sarcopenia. The aim of this narrative review is to provide an update on the effects of glucose-lowering drugs on sarcopenia in individuals with T2DM, focusing on the parameters used to define sarcopenia: muscle strength (evaluated by handgrip strength), muscle quantity/quality (evaluated by appendicular lean mass or skeletal muscle mass and their indexes), and physical performance (evaluated by gait speed or short physical performance battery). Furthermore, we also describe the plausible mechanisms by which glucose-lowering drugs may impact on sarcopenia.

Tissue-specific role and associated downstream signaling pathways of adiponectin

According to the World Health Organization, metabolic syndrome (MetS) can be defined as a pathological condition characterized by abdominal obesity, insulin resistance, hypertension, and hyperlipidemia. The incidence of MetS keeps rising, as at least 35% of the USA population suffers from MetS. One of the worst comorbidities of metabolic syndrome are cardiovascular diseases that significantly amplifies the mortality associated with this syndrome. There is an urgent need to understand the pathophysiology of MetS to find novel diagnosis, treatment and management to mitigate the MetS and associated complications. Altered circulatory adiponectin levels have been implicated in MetS. Adiponectin has numerous biologic functions including antioxidative, anti-nitrative, anti-inflammatory, and cardioprotective effects. Being a pleiotropic hormone of multiple tissues, tissue-specific key signaling pathways of adiponectin will help finding specific target/s to blunt the pathophysiology of metabolic syndrome and associated disorders. The purpose of this review is to elucidate tissue-specific signaling pathways of adiponectin and possibly identify potential therapeutic targets for MetS as well as to evaluate the potential of adiponectin as a biomarker/therapeutic option in MetS.

From Mitochondria to Atherosclerosis: The Inflammation Path

Inflammation is a key process in metazoan organisms due to its relevance for innate defense against infections and tissue damage. However, inflammation is also implicated in pathological processes such as atherosclerosis. Atherosclerosis is a chronic inflammatory disease of the arterial wall where unstable atherosclerotic plaque rupture causing platelet aggregation and thrombosis may compromise the arterial lumen, leading to acute or chronic ischemic syndromes. In this review, we will focus on the role of mitochondria in atherosclerosis while keeping inflammation as a link. Mitochondria are the main source of cellular energy. Under stress, mitochondria are also capable of controlling inflammation through the production of reactive oxygen species (ROS) and the release of mitochondrial components, such as mitochondrial DNA (mtDNA), into the cytoplasm or into the extracellular matrix, where they act as danger signals when recognized by innate immune receptors. Primary or secondary mitochondrial dysfunctions are associated with the initiation and progression of atherosclerosis by elevating the production of ROS, altering mitochondrial dynamics and energy supply, as well as promoting inflammation. Knowing and understanding the pathways behind mitochondrial-based inflammation in atheroma progression is essential to discovering alternative or complementary treatments.

Pharmacological advances in mitochondrial therapy

Mitochondria play a vital role in cellular metabolism and are central mediator of intracellular signalling, cell differentiation, morphogenesis and demise. An increasingly higher number of pathologies is linked with mitochondrial dysfunction, which can arise from either genetic defects affecting core mitochondrial components or malfunctioning pathways impairing mitochondrial homeostasis. As such, mitochondria are considered an important target in several pathologies spanning from neoplastic to neurodegenerative diseases as well as metabolic syndromes. In this review we provide an overview of the state-of-the-art in mitochondrial pharmacology, focusing on the novel compounds that have been generated in the bid to correct mitochondrial aberrations. Our work aims to serve the scientific community working on translational medical science by highlighting the most promising pharmacological approaches to target mitochondrial dysfunction in disease.

Mitochondrial dysfunction in nonalcoholic fatty liver disease and alcohol related liver disease

Fatty liver disease constitutes a spectrum of liver diseases which begin with simple steatosis and may progress to advance stages of steatohepatitis, cirrhosis, and hepatocellular carcinoma (HCC). The two main etiologies are-alcohol related fatty liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD). NAFLD is a global health epidemic strongly associated with modern dietary habits and life-style. It is the second most common cause of chronic liver disease in the US after chronic hepatitis C virus (HCV) infection. Approximately 100 million people are affected with this condition in the US alone. Excessive intakes of calories, saturated fat and refined carbohydrates, and sedentary life style have led to explosion of this health epidemic in developing nations as well. ALD is the third most common cause of chronic liver disease in the US. Even though the predominant trigger for onset of steatosis is different in these two conditions, they share common themes in progression from steatosis to the advance stages. Oxidative stress (OS) is considered a very significant contributor to hepatocyte injury in these conditions. Mitochondrial dysfunction contributes to this OS. Role of mitochondrial dysfunction in pathogenesis of fatty liver diseases is emerging but far from completely understood. A better understanding is essential for more effective preventive and therapeutic interventions. Here, we discuss the pathogenesis and therapeutic approaches of NAFLD and ALD from a mitochondrial perspective.

Pioglitazone corrects dysregulation of skeletal muscle mitochondrial proteins involved in ATP synthesis in type 2 diabetes

CONTEXT

In this study, we aimed to identify the determinants of mitochondrial dysfunction in skeletal muscle (SKLM) of subjects with type 2 diabetes (T2DM), and to evaluate the effect of pioglitazone (PIO) on SKLM mitochondrial proteome.

METHODS

Two different groups of adults were studied. Group I consisted of 8 individuals with normal glucose tolerance (NGT) and 8 with T2DM, subjected to SKLM mitochondrial proteome analysis by 2D-gel electrophoresis followed by mass spectrometry-based protein identification. Group II included 24 individuals with NGT and 24 with T2DM, whose SKLM biopsies were subjected to immunoblot analysis. Of the 24 subjects with T2DM, 20 were randomized to receive placebo or PIO (15 mg daily) for 6 months. After 6 months of treatment, SKLM biopsy was repeated.

RESULTS

Mitochondrial proteomic analysis on Group I revealed that several mitochondrial proteins involved in oxidative metabolism were differentially expressed between T2DM and NGT groups, with a downregulation of ATP synthase alpha chain (ATP5A), electron transfer flavoprotein alpha-subunit (ETFA), cytochrome c oxidase subunit VIb isoform 1 (CX6B1), pyruvate dehydrogenase protein X component (ODPX), dihydrolipoamide dehydrogenase (DLDH), dihydrolipoamide-S-succinyltransferase (DLST), and mitofilin, and an up-regulation of hydroxyacyl-CoA-dehydrogenase (HCDH), 3,2-trans-enoyl-CoA-isomerase (D3D2) and delta3,5-delta2,4-dienoyl-CoA-isomerase (ECH1) in T2DM as compared to NGT subjects. By immunoblot analysis on SKLM lysates obtained from Group II we confirmed that, in comparison to NGT subjects, those with T2DM exhibited lower protein levels of ATP5A (-30%, P = 0.006), ETFA (-50%, P = 0.02), CX6B1 (-30%, P = 0.03), key factors for ATP biosynthesis, and of the structural protein mitofilin (-30%, P = 0.01). T2DM was associated with a reduced abundance of the enzymes involved in the Krebs cycle DLST and ODPX (-20%, P ≤ 0.05) and increased levels of HCDH and ECH1, enzymes implicated in the fatty acid catabolism (+30%, P ≤ 0.05). In subjects with type 2 diabetes treated with PIO for 6 months we found a restored SKLM protein abundance of ATP5A, ETFA, CX6B1, and mitofilin. Moreover, protein levels of HCDH and ECH1 were reduced by -10% and - 15% respectively (P ≤ 0.05 for both) after PIO treatment.

CONCLUSION

Type 2 diabetes is associated with reduced levels of mitochondrial proteins involved in oxidative phosphorylation and an increased abundance of enzymes implicated in fatty acid catabolism in SKLM. PIO treatment is able to improve SKLM mitochondrial proteomic profile in subjects with T2DM.

Mechanisms underlying the metabolic actions of testosterone in humans: A narrative review

The role of testosterone in improving sexual symptoms in men with hypogonadism is well known. However, recent studies indicate that testosterone plays an important role in several metabolic functions in males. Multiple PubMed searches were conducted with the use of the terms testosterone, insulin sensitivity, obesity, type 2 diabetes, anaemia, bone density, osteoporosis, fat mass, lean mass and body composition. This narrative review is focused on detailing the mechanisms that underlie the metabolic aspects of testosterone therapy in humans. Testosterone enhances insulin sensitivity in obese men with hypogonadism by decreasing fat mass, increasing lean mass, decreasing free fatty acids and suppressing inflammation. At a cellular level, testosterone increases the expression of insulin receptor β subunit, insulin receptor substrate-1, protein kinase B and glucose transporter type 4 in adipose tissue and adenosine 5'-monophosphate-activated protein kinase expression and activity in skeletal muscle. Observational studies show that long-term therapy with testosterone prevents progression from prediabetes to diabetes and improves HbA1c. Testosterone increases skeletal muscle satellite cell activator, fibroblast growth factor-2 and decreases expression of the muscle growth suppressors, myostatin and myogenic regulatory factor 4. Testosterone increases haematocrit by suppressing hepcidin and increasing expression of ferroportin along with that of transferrin receptor and plasma transferrin concentrations. Testosterone also increases serum osteocalcin concentrations, which may account for its anabolic actions on bone. In conclusion, testosterone exerts a series of potent metabolic effects, which include insulin sensitization, maintenance and growth of the skeletal muscle, suppression of adipose tissue growth and maintenance of erythropoiesis and haematocrit.

Peroxisome Proliferator-Activated Receptors as Molecular Links between Caloric Restriction and Circadian Rhythm

The circadian rhythm plays a chief role in the adaptation of all bodily processes to internal and environmental changes on the daily basis. Next to light/dark phases, feeding patterns constitute the most essential element entraining daily oscillations, and therefore, timely and appropriate restrictive diets have a great capacity to restore the circadian rhythm. One of the restrictive nutritional approaches, caloric restriction (CR) achieves stunning results in extending health span and life span via coordinated changes in multiple biological functions from the molecular, cellular, to the whole-body levels. The main molecular pathways affected by CR include mTOR, insulin signaling, AMPK, and sirtuins. Members of the family of nuclear receptors, the three peroxisome proliferator-activated receptors (PPARs), PPARα, PPARβ/δ, and PPARγ take part in the modulation of these pathways. In this non-systematic review, we describe the molecular interconnection between circadian rhythm, CR-associated pathways, and PPARs. Further, we identify a link between circadian rhythm and the outcomes of CR on the whole-body level including oxidative stress, inflammation, and aging. Since PPARs contribute to many changes triggered by CR, we discuss the potential involvement of PPARs in bridging CR and circadian rhythm.

Peroxisome Proliferator-Activated Receptors and Caloric Restriction-Common Pathways Affecting Metabolism, Health, and Longevity

Caloric restriction (CR) is a traditional but scientifically verified approach to promoting health and increasing lifespan. CR exerts its effects through multiple molecular pathways that trigger major metabolic adaptations. It influences key nutrient and energy-sensing pathways including mammalian target of rapamycin, Sirtuin 1, AMP-activated protein kinase, and insulin signaling, ultimately resulting in reductions in basic metabolic rate, inflammation, and oxidative stress, as well as increased autophagy and mitochondrial efficiency. CR shares multiple overlapping pathways with peroxisome proliferator-activated receptors (PPARs), particularly in energy metabolism and inflammation. Consequently, several lines of evidence suggest that PPARs might be indispensable for beneficial outcomes related to CR. In this review, we present the available evidence for the interconnection between CR and PPARs, highlighting their shared pathways and analyzing their interaction. We also discuss the possible contributions of PPARs to the effects of CR on whole organism outcomes.

Fibroblast growth factor 21 protects against lipotoxicity-induced pancreatic β-cell dysfunction via regulation of AMPK signaling and lipid metabolism

Fibroblast growth factor 21 (FGF21) is known as a potent metabolic regulator but its protective mechanisms against lipotoxicity-induced β-cell dysfunction and apoptosis remain elusive. Here, we aimed to examine the regulatory pathways whereby FGF21 mediates islet lipid metabolism in lipotoxicity-treated cells and animal models. Rat β-cell line (INS-1E cells) and islets isolated from C57/BL6J mice were exposed to palmitic acid (PA) with/without FGF21, mimicking lipotoxic conditions. Resultant insulin secretion and intracellular signaling were analyzed with Western blotting and RNA-seq. C57/BL6J and global FGF21 knockout (KO) mice were fed with a high-fat diet (HFD) to induce lipotoxicity and given with a long-acting mimetic of FGF21. Insulin resistance and β-cell function were then assessed using homeostasis model assessment of insulin resistance (HOMA-IR) and insulinogenic index. FGF21 ameliorated PA-induced lipid accumulation, reversed cell apoptosis, and enhanced glucose-stimulated insulin secretion (GSIS) as impaired by lipotoxicity in islet β-cells. Mechanistically, FGF21 exerted its beneficial effects through activation of AMPK-ACC (acetyl-CoA carboxylase) pathway and peroxisome proliferation-activated receptors (PPARs) δ/γ signaling, thus increasing the levels of carnitine palmitoyltransferase-1A (CPT1A) and leading to increased fatty acid (FA) oxidation and reduced lipid deposition in β-cells. Interestingly, FGF21 reduced PA-induced cell death via restoration of the expression of apoptosis inhibitor Birc3. In vivo studies further showed that FGF21 is critical for islet insulinogenic capacity and normal function in the context of HFD-treated animals. FGF21 down-regulates islet cell lipid accumulation, probably via activation of AMPK-ACC and PPARδ/γ signaling, and reduces cell death under lipotoxicity, indicating that FGF21 is protective against lipotoxicity-induced β-cell dysfunction and apoptosis.

Insulin Resistance the Link between T2DM and CVD: Basic Mechanisms and Clinical Implications

Insulin resistance (IR) is a cardinal feature of type 2 diabetes mellitus (T2DM). It also is associated with multiple metabolic abnormalities which are known cardiovascular disease (CVD) risk factors. Thus, IR not only contributes to the development of hyperglycemia in T2DM patients, but also to the elevated CVD risk. Improving insulin sensitivity is anticipated to both lower the plasma glucose concentration and decrease CVD risk in T2DM patients, independent of glucose control. We review the molecular mechanisms and metabolic consequences of IR in T2DM patients and discuss the importance of addressing IR in the management of T2DM.

Testosterone Increases the Expression and Phosphorylation of AMP Kinase α in Men With Hypogonadism and Type 2 Diabetes

CONTEXT

Adenosine 5'-monophosphate-activated protein kinase-α (AMPKα) is a mediator of exercise-induced glucose uptake in skeletal muscle.

OBJECTIVE

We evaluated whether AMPKα expression and phosphorylation are reduced in skeletal muscle and adipose tissue of patients with hypogonadotropic hypogonadism (HH), and whether testosterone replacement therapy results in restoration of the expression and phosphorylation of AMPKα.

DESIGN

This is a secondary analysis of a previously completed trial that showed an insulin-sensitizing effect of testosterone therapy in men with type 2 diabetes and HH.

SETTING

Clinical research center at university.

PATIENTS

Thirty-two men with HH and 32 eugonadal men were compared at baseline.

INTERVENTIONS

Men with HH were treated with intramuscular injections of testosterone or placebo every 2 weeks for 22 weeks. Quadriceps muscle biopsies and subcutaneous abdominal fat biopsies were obtained before and after 4-hour euglycemic hyperinsulinemic clamp, prior to and after testosterone or placebo therapy.

OUTCOME MEASURES AND RESULTS

mRNA expression of AMPKα in hypogonadal men was lower by 37% in adipose tissue and 29% in skeletal muscle, respectively, compared with levels in eugonadal men, while phosphorylated AMPKα was lower by 22% and 28%, respectively. Following testosterone replacement, the expression of AMPKα did not alter in the fasting state but increased markedly by 41% and 46% in adipose tissue and muscle, respectively, after the clamp. In contrast, phosphorylated AMPKα increased by 69% in muscle after testosterone therapy but did not change following the clamp.

CONCLUSIONS

Testosterone modulates the expression of AMPKα and phosphorylated AMPKα. These effects may contribute to the improved insulin sensitivity following testosterone therapy.

Impaired Mitochondrial Function Results from Oxidative Stress in the Full-Term Placenta of Sows with Excessive Back-Fat

The aim of this study was to determine the effect of excessive back-fat (BF) of sows on placental oxidative stress, ATP generation, mitochondrial alterations in content and structure, and mitochondrial function in isolated trophoblasts. Placental tissue was collected by vaginal delivery from BFI (15-20 mm, n = 10) and BFII (21-27 mm, n = 10) sows formed according to BF at mating. Our results demonstrated that excessive back-fat contributed to augmented oxidative stress in term placenta, as evidenced by excessive production of ROS, elevated protein carbonylation, and reduced SOD, GSH-PX, and CAT activities (p < 0.05). Indicative of mitochondrial dysfunction, reduced mitochondrial respiration in cultured trophoblasts was linked to decreased ATP generation, lower mitochondrial Complex I activity and reduced expression of electron transport chain subunits in placenta of BFII sows (p < 0.05). Meanwhile, we observed negative alterations in mitochondrial biogenesis and structure in the placenta from BFII group (p < 0.05). Finally, our in vitro studies showed lipid-induced ROS production resulted in mitochondrial alterations in trophoblasts, and these effects were blocked by antioxidant treatment. Together, these data reveal that excessive back-fat aggravates mitochondrial injury induced by increased oxidative stress in pig term placenta, which may have detrimental consequences on placental function and therefore impaired fetal growth and development.

The Impact of Antidiabetic Agents on Sarcopenia in Type 2 Diabetes: A Literature Review

Sarcopenia is a geriatric syndrome characterized by decline of skeletal muscle mass and function. Contributing factors include nutritional, genetic, inflammatory, and endocrinal factors. The reported prevalence of sarcopenia in type 2 diabetes mellitus is high, especially in patients with poor glycemic control. Additionally, antidiabetic agents may alter the balance between protein synthesis and degradation through various mechanisms of skeletal muscle mass regulation. This study reviewed the literature on the pathogenesis of sarcopenia in diabetes mellitus and the current understanding of whether antidiabetic agents contribute positively or negatively to sarcopenia and muscle wasting.

Insulin Resistance and Atherosclerosis: Implications for Insulin-Sensitizing Agents

Patients with type 2 diabetes mellitus (T2DM) are at high risk for macrovascular complications, which represent the major cause of mortality. Despite effective treatment of established cardiovascular (CV) risk factors (dyslipidemia, hypertension, procoagulant state), there remains a significant amount of unexplained CV risk. Insulin resistance is associated with a cluster of cardiometabolic risk factors known collectively as the insulin resistance (metabolic) syndrome (IRS). Considerable evidence, reviewed herein, suggests that insulin resistance and the IRS contribute to this unexplained CV risk in patients with T2DM. Accordingly, CV outcome trials with pioglitazone have demonstrated that this insulin-sensitizing thiazolidinedione reduces CV events in high-risk patients with T2DM. In this review the roles of insulin resistance and the IRS in the development of atherosclerotic CV disease and the impact of the insulin-sensitizing agents and of other antihyperglycemic medications on CV outcomes are discussed.

Pharmacological activation of peroxisome proliferator-activated receptor γ (PPAR-γ) protects against hypoxia-associated fetal growth restriction

The hypoxia of high-altitude (HA) residence increases the risk of intrauterine growth restriction (IUGR) and preeclampsia 3-fold, augmenting perinatal morbidity and mortality and the risk for childhood and adult disease. Currently, no effective therapies exist to prevent these vascular disorders of pregnancy. The peroxisome proliferator-activated receptor γ (PPAR-γ) is an important regulator of uteroplacental vascular development and function and has been implicated in the pathogenesis of IUGR and preeclampsia. Here, we used a model of HA pregnancy in mice to determine whether hypoxia-induced fetal growth restriction reduces placental PPAR-γ protein expression and placental vascularization and, if so, to evaluate the effectiveness of the selective PPAR-γ agonist pioglitazone (PIO) for preventing hypoxia-induced IUGR. Hypoxia resulted in asymmetric IUGR, placental insufficiency, and reduced placental PPAR-γ expression; PIO prevented approximately half of the fetal growth restriction and attenuated placental insufficiency. PIO did not affect fetal growth under normoxia. Although PIO was beneficial for fetal growth, PIO treatment reduced placental vascular density of the labrynthine zone in normoxic and hypoxic (Hx) conditions, and mean vascular area was reduced in the Hx group. Our results suggest that pharmacological PPAR-γ activation is a potential strategy for preventing IUGR in pregnancies complicated by hypoxia, although further studies are needed to identify its likely metabolic or vascular mechanisms.-Lane, S. L., Dodson, R. B., Doyle, A. S., Park, H., Rathi, H., Matarrazo, C. J., Moore, L. G., Lorca, R. A., Wolfson, G. H., Julian, C. G. Pharmacological activation of peroxisome proliferator-activated receptor γ (PPAR-γ) protects against hypoxia-associated fetal growth restriction.

Glucose consumption assay discovers coptisine with beneficial effect on diabetic mice

Many drugs with anti-diabetic effects regulate glucose consumption in peripheral tissues. Via cellular glucose consumption assays, we identified that coptisine, a main effective constituent from the plant Coptis chinensis, enhanced hepatic and skeletal muscle glucose consumption. We further explored its effects on glucose metabolism in diabetic animals to elucidate its mechanism of action. Our results showed that coptisine did not show cytotoxicity. Intragastric administration of coptisine for ten days in normal ICR mice markedly decreased fasting blood-glucose levels without significant effects on body weight. In alloxan-induced type 1 diabetic mice, intragastric administration of coptisine for 28 days decreased fasting and non-fasting blood-glucose levels as well. In type 2 diabetic KKAy mice, intragastric administration of coptisine for nine weeks improved glucose tolerance. It decreased fasting/non-fasting blood-glucose and fructosamine levels. Coptisine decreased low-density lipoprotein and total cholesterol levels, however, had no significant effect on triglyceride levels. Coptisine increased AMPK phosphorylation while decreasing Akt phosphorylation in HepG2 hepatic cells and C2C12 myotubes. Coptisine also reduced mitochondrial respiration in isolated and cellular mitochondria, suggesting that coptisine lowered cellular energy levels. In particularly, coptisine administration (10^-6 M) decreased the mitochondrial oxygen consumption rate (OCR) with a greater extracellular acidification rate (ECAR), resulting in an oxidative-to-glycolysis phosphorylation shifted for cellular energy generation. Our results demonstrate that coptisine acts as an enhancer of peripheral glucose consumption could improve glucose metabolism in diabetic animals. Coptisine may serve as a novel anti-diabetic agent and warrant further evaluation.

Pioglitazone Improves Mitochondrial Organization and Bioenergetics in Down Syndrome Cells

Mitochondrial dysfunction plays a primary role in neurodevelopmental anomalies and neurodegeneration of Down syndrome (DS) subjects. For this reason, targeting mitochondrial key genes, such as PGC-1α/PPARGC1A, is emerging as a good therapeutic approach to attenuate cognitive disability in DS. After demonstrating the efficacy of the biguanide metformin (a PGC-1α activator) in a cell model of DS, we extended the study to other molecules that regulate the PGC-1α pathway acting on PPAR genes. We, therefore, treated trisomic fetal fibroblasts with different doses of pioglitazone (PGZ) and evaluated the effects on mitochondrial dynamics and function. Treatment with PGZ significantly increased mRNA and protein levels of PGC-1α. Mitochondrial network was fully restored by PGZ administration affecting the fission-fusion mitochondrial machinery. Specifically, optic atrophy 1 (OPA1) and mitofusin 1 (MFN1) were upregulated while dynamin-related protein 1 (DRP1) was downregulated. These effects, together with a significant increase of basal ATP content and oxygen consumption rate, and a significant decrease of reactive oxygen species (ROS) production, provide strong evidence of an overall improvement of mitochondria bioenergetics in trisomic cells. In conclusion, we demonstrate that PGZ is able to improve mitochondrial phenotype even at low concentrations (0.5 μM). We also speculate that a combination of drugs that target mitochondrial function might be advantageous, offering potentially higher efficacy and lower individual drug dosage.

Mitochondrial Genetic Disorders: Cell Signaling and Pharmacological Therapies

Mitochondrial fatty acid oxidation (FAO) and respiratory chain (RC) defects form a large group of inherited monogenic disorders sharing many common clinical and pathophysiological features, including disruption of mitochondrial bioenergetics, but also, for example, oxidative stress and accumulation of noxious metabolites. Interestingly, several transcription factors or co-activators exert transcriptional control on both FAO and RC genes, and can be activated by small molecules, opening to possibly common therapeutic approaches for FAO and RC deficiencies. Here, we review recent data on the potential of various drugs or small molecules targeting pivotal metabolic regulators: peroxisome proliferator activated receptors (PPARs), sirtuin 1 (SIRT1), AMP-activated protein kinase (AMPK), and protein kinase A (PKA)) or interacting with reactive oxygen species (ROS) signaling, to alleviate or to correct inborn FAO or RC deficiencies in cellular or animal models. The possible molecular mechanisms involved, in particular the contribution of mitochondrial biogenesis, are discussed. Applications of these pharmacological approaches as a function of genotype/phenotype are also addressed, which clearly orient toward personalized therapy. Finally, we propose that beyond the identification of individual candidate drugs/molecules, future pharmacological approaches should consider their combination, which could produce additive or synergistic effects that may further enhance their therapeutic potential.

Pioglitazone: The forgotten, cost-effective cardioprotective drug for type 2 diabetes

Type 2 diabetes individuals are at high risk for macrovascular complications: myocardial infarction, stroke and cardiovascular mortality. Recent cardiovascular outcome trials have demonstrated that agents in two antidiabetic classes (SGLT2 inhibitors and GLP-1 receptor agonists) reduce major adverse cardiovascular events. However, there is strong evidence that an older and now generically available medication, the thiazolidinedione, pioglitazone, can retard the atherosclerotic process (PERISCOPE and Chicago) and reduce cardiovascular events in large randomized prospective cardiovascular outcome trials (IRIS and PROactive). Pioglitazone is a potent insulin sensitizer, preserves beta-cell function, causes durable reduction in HbA1c, corrects multiple components of metabolic syndrome and improves nonalcoholic fatty liver disease/nonalcoholic steatohepatitis. Adverse effects (weight gain, fluid retention, fractures) must be considered, but are diminished with lower doses and are arguably outweighed by these multiple benefits. With healthcare expenses attributable to diabetes increasing rapidly, this cost-effective drug requires reconsideration in the therapeutic armamentarium for the disease.

Examining the Potential of Developing and Implementing Use of Adiponectin-Targeted Therapeutics for Metabolic and Cardiovascular Diseases

Cardiometabolic diseases encompass those affecting the heart and vasculature as well as other metabolic problems, such as insulin resistance, diabetes, and non-alcoholic fatty liver disease. These diseases tend to have common risk factors, one of which is impaired adiponectin action. This may be due to reduced bioavailability of the hormone or resistance to its effects on target tissues. A strong negative correlation between adiponectin levels and cardiometabolic diseases has been well-documented and research shown that adiponectin has cardioprotective, insulin sensitizing and direct beneficial metabolic effects. Thus, therapeutic approaches to enhance adiponectin action are widely considered to be desirable. The complexity of adiponectin structure and function has so far made progress in this area less than ideal. In this article we will review the effects and mechanism of action of adiponectin on cardiometabolic tissues, identify scenarios where enhancing adiponectin action would be of clinical value and finally discuss approaches via which this can be achieved.

p-21 Activated Kinase as a Molecular Target for Chemoprevention in Diabetes

Hypothesis: Anti-diabetic drugs modulate p-21 activated kinase (PAK) signaling. Introduction: Type 2 diabetes mellitus (T2DM) is a chronic inflammatory disease associated with increased cancer risk. PAK signaling is implicated in cellular homeostasis when regulated, and cancer when unrestrained. Recent reports provided a role for PAK signaling in glucose homeostasis, but the role of PAKs in the pathogenesis of T2DM is unknown. Here, we performed a mini-meta-analysis to explore if anti-diabetic drugs modify PAK signaling pathways, and provide insight regarding modulation of these pathways, to potentially reduce diabetes-associated cancer risk. Methods: PAK interacting partners in T2DM were identified using the online STRING database. Correlation studies were performed via systematic literature review to understand the effect of anti-diabetic drugs on PAK signaling. A mini-meta-analysis correlated multiple clinical studies and revealed the overall clinical response rate and percentage of adverse events in piogliazone (n = 53) and metformin (n = 91) treated patients with PAK-associated diseases. Results: A total of 30 PAK interacting partners were identified (10: reduced beta-cell mass; 10: beta-cell dysfunction; 10: obesity-insulin resistance), which were highly associated with Wnt, and G-protein signaling. The anti-diabetic drug metformin activated signaling pathways upstream; whereas pioglitazone inhibited pathways downstream of PAK. Overall, clinical response upon pioglitazone treatment was 53%. Seventy-nine percent of pioglitazone and 75% of metformin treated patients had adverse events. Pioglitazone reduced molecular-PAK biomarkers of proliferation (Ki67 and CyclinD1), and metformin had the opposite effect. Conclusions: PAK signaling in T2DM likely involves Wnt and G-protein signaling, which may be altered by the anti-diabetic drugs metformin and pioglitazone. Apart from the therapeutic limitations of adverse events, pioglitazone may be promising in chemoprevention. However long-term multi-centered studies, which initiate pioglitazone treatment early will be required to fully assess the full potential of these drugs.

Nonalcoholic fatty liver disease: current concepts, epidemiology and management strategies

Nonalcoholic fatty liver disease (NAFLD) is now the most prevalent liver disease in the world. It involves a spectrum of conditions from hepatic steatosis to nonalcoholic steatohepatitis and liver fibrosis, and is a major cause of cirrhosis and hepatocellular carcinoma. It is defined by presence of steatosis in 5% of hepatocytes or more in the absence of other causes of fatty liver. The metabolic syndrome is the major known risk factor for NAFLD. Dietary contributors such as high fructose intake and coffee consumption appear to increase and decrease the risk of disease respectively, but these links are unclear. Genetic associations have also been identified. The estimated prevalence of the disease varies according to diagnostic method and population demographics. It appears to be a major issue in Europe with population studies showing up to 50% of the individuals are affected while in the USA one in three adults are estimated to have NAFLD. Laboratory investigations and ultrasound are typically first-line investigations. Fibrosis may be assessed noninvasively through transient elastography and biomarkers but liver biopsy remains the gold standard to quantify hepatic damage. Associated comorbidities include cardiovascular disease and chronic kidney disease. Weight loss, dietary changes and exercise are recommended in management. Medications should be considered to manage underlying risk factors including insulin resistance. Surgical options include bariatric procedures and liver transplantation. The combination of rising prevalence and significant potential complications warrant further research into NAFLD, particularly in areas with research gaps including Eastern Europe.

Mitochondrial role in the neonatal predisposition to developing nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a global epidemic in obese children and adults, and the onset might have fetal origins. A growing body of evidence supports the role of developmental programming, whereby the maternal environment affects fetal and infant development, altering the risk profile for disease later in life. Human and nonhuman primate studies of maternal obesity demonstrate that risk factors for pediatric obesity and NAFLD begin in utero. The pathologic mechanisms for NAFLD are multifactorial but have centered on altered mitochondrial function/dysfunction that might precede insulin resistance. Compared with the adult liver, the fetal liver has fewer mitochondria, low activity of the fatty acid metabolic enzyme carnitine palmitoyl-CoA transferase-1, and little or no gluconeogenesis. Exposure to excess maternal fuels during fetal life uniquely alters hepatic fatty acid oxidation, tricarboxylic acid cycle activity, de novo lipogenesis, and mitochondrial health. These events promote increased oxidative stress and excess triglyceride storage, and, together with altered immune function and epigenetic changes, they prime the fetal liver for NAFLD and might drive the risk for nonalcoholic steatohepatitis in the next generation.

Chronic kidney disease attenuates the plasma metabolome response to insulin

Chronic kidney disease (CKD) leads to decreased sensitivity to the metabolic effects of insulin, contributing to protein energy wasting and muscle atrophy. Targeted metabolomics profiling during hyperinsulinemic-euglycemic insulin clamp testing may help identify aberrant metabolic pathways contributing to insulin resistance in CKD. Using targeted metabolomics profiling, we examined the plasma metabolome in 95 adults without diabetes in the fasted state (58 with CKD, 37 with normal glomerular filtration rate [GFR]) who underwent hyperinsulinemic-euglycemic clamp. We assessed heterogeneity in fasting metabolites and the response to insulin to identify potential metabolic pathways linking CKD with insulin resistance. Baseline differences and effect modification by CKD status on changes with insulin clamp testing were adjusted for confounders. Mean GFR among participants with CKD was 37.3 compared with 89.3 ml/min per 1.73 m2 among controls. Fasted-state differences between CKD and controls included abnormalities in tryptophan metabolism, ubiquinone biosynthesis, and the TCA cycle. Insulin infusion markedly decreased metabolite levels, predominantly amino acids and their metabolites. CKD was associated with attenuated insulin-induced changes in nicotinamide, arachidonic acid, and glutamine/glutamate metabolic pathways. Metabolomics profiling suggests disruption in amino acid metabolism and mitochondrial function as putative manifestations or mechanisms of the impaired anabolic effects of insulin in CKD.

Pioglitazone improves hepatic mitochondrial function in a mouse model of nonalcoholic steatohepatitis

Pioglitazone is effective in improving insulin resistance and liver histology in patients with nonalcoholic steatohepatitis (NASH). Because dysfunctional mitochondrial metabolism is a central feature of NASH, we hypothesized that an important target of pioglitazone would be alleviating mitochondrial oxidative dysfunction. To this end, we studied hepatic mitochondrial metabolism in mice fed high-fructose high-transfat diet (TFD) supplemented with pioglitazone for 20 wk, using nuclear magnetic resonance-based ¹³C isotopomer analysis. Pioglitazone improved whole body and adipose insulin sensitivity in TFD-fed mice. Furthermore, pioglitazone reduced intrahepatic triglyceride content and fed plasma ketones and hepatic TCA cycle flux, anaplerosis, and pyruvate cycling in mice with NASH. This was associated with a marked reduction in most intrahepatic diacylglycerol classes and, to a lesser extent, some ceramide species (C22:1, C23:0). Considering the cross-talk between mitochondrial function and branched-chain amino acid (BCAA) metabolism, pioglitazone's impact on plasma BCAA profile was determined in a cohort of human subjects. Pioglitazone improved the plasma BCAA concentration profile in patients with NASH. This appeared to be related to an improvement in BCAA degradation in multiple tissues. These results provide evidence that pioglitazone-induced changes in NASH are related to improvements in hepatic mitochondrial oxidative dysfunction and changes in whole body BCAA metabolism.

Effect of pioglitazone on cardiometabolic profiles and safety in patients with type 2 diabetes undergoing percutaneous coronary artery intervention: a prospective, multicenter, randomized trial

Pioglitazone has superior antiatherosclerotic effects compared with other classes of antidiabetic agents, and there is substantial evidence that pioglitazone improves cardiovascular (CV) outcomes. However, there is also a potential risk of worsening heart failure (HF). Therefore, it is clinically important to determine whether pioglitazone is safe in patients with type 2 diabetes mellitus (T2DM) who require treatment for secondary prevention of CV disease, since they have an intrinsically higher risk of HF. This prospective, multicenter, open-label, randomized study investigated the effects of pioglitazone on cardiometabolic profiles and CV safety in T2DM patients undergoing elective percutaneous coronary intervention (PCI) using bare-metal stents or first-generation drug-eluting stents. A total of 94 eligible patients were randomly assigned to either a pioglitazone or conventional (control) group, and pioglitazone was started the day before PCI. Cardiometabolic profiles were evaluated before PCI and at primary follow-up coronary angiography (5-8 months). Pioglitazone treatment reduced HbA1c levels to a similar degree as conventional treatment (pioglitazone group 6.5 to 6.0%, P < 0.01; control group 6.5 to 5.9%, P < 0.001), without body weight gain. Levels of high-molecular weight adiponectin increased more in the pioglitazone group than the control group (P < 0.001), and the changes were irrespective of baseline glycemic control. Furthermore, pioglitazone significantly reduced plasma levels of natriuretic peptides and preserved cardiac systolic and diastolic function (assessed by echocardiography) without incident hospitalization for worsening HF. The incidence of clinical adverse events was also comparable between the groups. These results indicate that pioglitazone treatment before and after elective PCI may be tolerable and clinically safe and may improve cardiometabolic profiles in T2DM patients.