Insulin sensitizing and anti-inflammatory effects of thiazolidinediones are heightened in obese patients

Effect of pioglitazone on serum FGF23 levels among patients with diabetic kidney disease: a randomized controlled trial

AIM

Elevated fibroblast growth factor-23 (FGF23) is an established marker of cardiovascular disease among patients with type 2 diabetes (T2DM) and chronic kidney disease (CKD). Recently, circulating FGF23 positively correlated with insulin resistance level among patients with CKD. Pioglitazone improves insulin sensitivity and it may have potential for treating CKD-related FGF23 overactivity.

METHODS

A randomized, open-label, controlled trial was performed among patients with T2DM and CKD. Eligible participants were randomly assigned to either oral 15 mg/day of pioglitazone (N = 22) or control group (N = 24) for 16 weeks. Serum FGF23 and homeostatic Model Assessment of Insulin Resistance (HOMA-IR) were measured.

RESULTS

Forty-six patients completed the trial. After 16 weeks of treatment, significant decreases in serum intact FGF23 level (median change - 49.01 (IQR, - 103.51 to - 24.53) vs. 1.07 (IQR, - 22.4-39.53) pg/mL, P = 0.01) and HOMA-IR (mean change - 1.41 (95% CI, - 2.24 to - 0.57) vs. - 0.05 (95% CI, - 1.00-0.89), P = 0.031) were observed in the pioglitazone group compared with the control group. HemoglobinA1C also significantly decreased in the pioglitazone group compared with the control group. No difference was found in the changes of serum phosphorus, calcium and serum intact parathyroid hormone between the two groups. Changes of FGF23 were positively associated with changes of HOMA-IR (R = 0.47) and insulin levels (R = 0.47). No serious adverse event was reported during the study.

CONCLUSION

This study confirmed that pioglitazone effectively reduced serum FGF23 levels and related to improved insulin sensitivity among patients with T2DM and CKD.

CLINICAL TRIAL REGISTRATION

TCTR20210316009.

Gut microbiota and obesity: New insights

Obesity is a pathology whose incidence is increasing throughout the world. There are many pathologies associated with obesity. In recent years, the influence of the microbiota on both health and pathological states has been known. There is growing information related to changes in the microbiome and obesity, as well as its associated pathologies. Changes associated with age, exercise, and weight changes have been described. In addition, metabolic changes associated with the microbiota, bariatric surgery, and fecal matter transplantation are described. In this review, we summarize the biology and physiology of microbiota in obese patients, its role in the pathophysiology of several disorders associated, and the emerging therapeutic applications of prebiotics, probiotics, and fecal microbiota transplantation.

Can We Decrease Epicardial and Pericardial Fat in Patients With Diabetes?

Diabetes mellitus (DM) is a chronic and complex metabolic disorder and also an important cause of cardiovascular (CV) disease (CVD). Patients with type 2 DM (T2DM) and obesity show a greater propensity for visceral fat deposition (and excessive fat deposits elsewhere) and the link between adiposity and CVD risk is greater for visceral than for subcutaneous (SC) adipose tissue (AT). There is growing evidence that epicardial AT (EAT) and pericardial AT (PAT) play a role in the development of DM-related atherosclerosis, atrial fibrillation (AF), myocardial dysfunction, and heart failure (HF). In this review, we will highlight the importance of PAT and EAT in patients with DM. We also consider therapeutic interventions that could have a beneficial effect in terms of reducing the amount of AT and thus CV risk. EAT is biologically active and a likely determinant of CV morbidity and mortality in patients with DM, given its anatomical characteristics and proinflammatory secretory pattern. Consequently, modification of EAT/PAT may become a therapeutic target to reduce the CV burden. In patients with DM, a low calorie diet, exercise, antidiabetics and statins may change the quantity of EAT, PAT or both, alter the secretory pattern of EAT, improve the metabolic profile, and reduce inflammation. However, well-designed studies are needed to clearly define CV benefits and a therapeutic approach to EAT/PAT in patients with DM.

Pioglitazone does not synergize with mirabegron to increase beige fat or further improve glucose metabolism

BACKGROUND

Beige and brown adipose tissue (BAT) are associated with improved metabolic homeostasis. We recently reported that the β₃-adrenergic receptor agonist mirabegron induced beige adipose tissue in obese insulin-resistant subjects, and this was accompanied by improved glucose metabolism. Here we evaluated pioglitazone treatment with a combination pioglitazone and mirabegron treatment and compared these with previously published data evaluating mirabegron treatment alone. Both drugs were used at FDA-approved dosages.

METHODS

We measured BAT by PET CT scans, measured beige adipose tissue by immunohistochemistry, and comprehensively characterized glucose and lipid homeostasis and insulin sensitivity by euglycemic clamp and oral glucose tolerance tests. Subcutaneous white adipose tissue, muscle fiber type composition and capillary density, lipotoxicity, and systemic inflammation were evaluated by immunohistochemistry, gene expression profiling, mass spectroscopy, and ELISAs.

RESULTS

Treatment with pioglitazone or the combination of pioglitazone and mirabegron increased beige adipose tissue protein marker expression and improved insulin sensitivity and glucose homeostasis, but neither treatment induced BAT in these obese subjects. When the magnitude of the responses to the treatments was evaluated, mirabegron was found to be the most effective at inducing beige adipose tissue. Although monotherapy with either mirabegron or pioglitazone induced adipose beiging, combination treatment resulted in less beiging than either alone. The 3 treatments also had different effects on muscle fiber type switching and capillary density.

CONCLUSION

The addition of pioglitazone to mirabegron treatment does not enhance beiging or increase BAT in obese insulin-resistant research participants.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02919176.

FUNDING

NIH DK112282 and P20GM103527 and Clinical and Translational Science Awards grant UL1TR001998.

Adipose Tissue Immunomodulation: A Novel Therapeutic Approach in Cardiovascular and Metabolic Diseases

Adipose tissue is a critical regulator of systemic metabolism and bodily homeostasis as it secretes a myriad of adipokines, including inflammatory and anti-inflammatory cytokines. As the main storage pool of lipids, subcutaneous and visceral adipose tissues undergo marked hypertrophy and hyperplasia in response to nutritional excess leading to hypoxia, adipokine dysregulation, and subsequent low-grade inflammation that is characterized by increased infiltration and activation of innate and adaptive immune cells. The specific localization, physiology, susceptibility to inflammation and the heterogeneity of the inflammatory cell population of each adipose depot are unique and thus dictate the possible complications of adipose tissue chronic inflammation. Several lines of evidence link visceral and particularly perivascular, pericardial, and perirenal adipose tissue inflammation to the development of metabolic syndrome, insulin resistance, type 2 diabetes and cardiovascular diseases. In addition to the implication of the immune system in the regulation of adipose tissue function, adipose tissue immune components are pivotal in detrimental or otherwise favorable adipose tissue remodeling and thermogenesis. Adipose tissue resident and infiltrating immune cells undergo metabolic and morphological adaptation based on the systemic energy status and thus a better comprehension of the metabolic regulation of immune cells in adipose tissues is pivotal to address complications of chronic adipose tissue inflammation. In this review, we discuss the role of adipose innate and adaptive immune cells across various physiological and pathophysiological states that pertain to the development or progression of cardiovascular diseases associated with metabolic disorders. Understanding such mechanisms allows for the exploitation of the adipose tissue-immune system crosstalk, exploring how the adipose immune system might be targeted as a strategy to treat cardiovascular derangements associated with metabolic dysfunctions.

Remodeling adipose tissue inflammasome for type 2 diabetes mellitus treatment: Current perspective and translational strategies

Obesity-associated type 2 diabetes mellitus (T2DM) is characterized by low-grade chronic systemic inflammation that arises primarily from the white adipose tissue. The interplay between various adipose tissue-derived chemokines drives insulin resistance in T2DM and has therefore become a subject of rigorous investigation. The adipocytokines strongly associated with glucose homeostasis include tumor necrosis factor-α, various interleukins, monocyte chemoattractant protein-1, adiponectin, and leptin, among others. Remodeling the adipose tissue inflammasome in obesity-associated T2DM is likely to treat the underlying cause of the disease and bring significant therapeutic benefit. Various strategies have been adopted or are being investigated to modulate the serum/tissue levels of pro- and anti-inflammatory adipocytokines to improve glucose homeostasis in T2DM. These include use of small molecule agonists/inhibitors, mimetics, antibodies, gene therapy, and other novel formulations. Here, we discuss adipocytokines that are strongly associated with insulin activity and therapies that are under investigation for modulation of their levels in the treatment of T2DM.

To Probe Full and Partial Activation of Human Peroxisome Proliferator-Activated Receptors by Pan-Agonist Chiglitazar Using Molecular Dynamics Simulations

Chiglitazar is a promising new-generation insulin sensitizer with low reverse effects for the treatment of type II diabetes mellitus (T2DM) and has shown activity as a nonselective pan-agonist to the human peroxisome proliferator-activated receptors (PPARs) (i.e., full activation of PPARγ and a partial activation of PPARα and PPARβ/δ). Yet, it has no high-resolution complex structure with PPARs and its detailed interactions and activation mechanism remain unclear. In this study, we docked chiglitazar into three experimentally resolved crystal structures of hPPAR subtypes, PPARα, PPARβ/δ, and PPARγ, followed by 3 μs molecular dynamics simulations for each system. Our MM-GBSA binding energy calculation revealed that chiglitazar most favorably bound to hPPARγ (-144.6 kcal/mol), followed by hPPARα (-138.0 kcal/mol) and hPPARβ (-135.9 kcal/mol), and the order is consistent with the experimental data. Through the decomposition of the MM-GBSA binding energy by residue and the use of two-dimensional interaction diagrams, key residues involved in the binding of chiglitazar were identified and characterized for each complex system. Additionally, our detailed dynamics analyses support that the conformation and dynamics of helix 12 play a critical role in determining the activities of the different types of ligands (e.g., full agonist vs. partial agonist). Rather than being bent fully in the direction of the agonist versus antagonist conformation, a partial agonist can adopt a more linear conformation and have a lower degree of flexibility. Our finding may aid in further development of this new generation of medication.

Chronic Adipose Tissue Inflammation Linking Obesity to Insulin Resistance and Type 2 Diabetes

Obesity is one of the major health burdens of the 21st century as it contributes to the growing prevalence of its related comorbidities, including insulin resistance and type 2 diabetes. Growing evidence suggests a critical role for overnutrition in the development of low-grade inflammation. Specifically, chronic inflammation in adipose tissue is considered a crucial risk factor for the development of insulin resistance and type 2 diabetes in obese individuals. The triggers for adipose tissue inflammation are still poorly defined. However, obesity-induced adipose tissue expansion provides a plethora of intrinsic signals (e.g., adipocyte death, hypoxia, and mechanical stress) capable of initiating the inflammatory response. Immune dysregulation in adipose tissue of obese subjects results in a chronic low-grade inflammation characterized by increased infiltration and activation of innate and adaptive immune cells. Macrophages are the most abundant innate immune cells infiltrating and accumulating into adipose tissue of obese individuals; they constitute up to 40% of all adipose tissue cells in obesity. In obesity, adipose tissue macrophages are polarized into pro-inflammatory M1 macrophages and secrete many pro-inflammatory cytokines capable of impairing insulin signaling, therefore promoting the progression of insulin resistance. Besides macrophages, many other immune cells (e.g., dendritic cells, mast cells, neutrophils, B cells, and T cells) reside in adipose tissue during obesity, playing a key role in the development of adipose tissue inflammation and insulin resistance. The association of obesity, adipose tissue inflammation, and metabolic diseases makes inflammatory pathways an appealing target for the treatment of obesity-related metabolic complications. In this review, we summarize the molecular mechanisms responsible for the obesity-induced adipose tissue inflammation and progression toward obesity-associated comorbidities and highlight the current therapeutic strategies.

Anti-inflammatory properties of antidiabetic agents

The reciprocal relationship between hyperglycemia and inflammation in the setting of diabetes mellitus has been the subject of extensive research. Insulin resistance, the hallmark of diabetic metabolic dysregulation, has been linked to the inflammatory cascade occurring mainly in adipose tissue. The main pathophysiologic processes facilitating the aforementioned interplay, is a phenotype switch of macrophages to the M1 class following gluco- and lipotoxicity and gut microbial remodeling. Given the correlation between inflammation and metabolic abnormalities, the elucidation of the exact mechanisms linking the two along with exploring the possible role of modulation of one in order to alter the other, could open up the possibility of novel therapeutic approaches for diabetes mellitus and its complications. Therefore, the aim of this review is to summarize the growing body of evidence concerning the molecular basis and results of pro-inflammatory processes in diabetic subjects along with the effect of current antidiabetic treatment options on tissue inflammation.

Nanoemulsion strategy of pioglitazone for the treatment of skin inflammatory diseases

Pioglitazone (PGZ) is a peroxisome proliferator-activated receptor agonist. Its role in the inflammatory response modulation paves the way for additional therapeutic applications. The purpose of this study was to develop a pioglitazone nanoemulsion (PGZ-NE) in order to investigate its anti-inflammatory efficacy on the skin. To that end, an NE vehicle developed for skin delivery was optimized and characterized. The resulting PGZ-NE showed good anti-inflammatory efficacy by decreasing the expression of inflammatory cytokines IL-6, IL-1β and TNF-α. The properties of the developed nanocarrier allowed achievement of a high permeation flux of PGZ through the skin as well as a high retained amount in the skin, likely due to the depot effect of ingredients, which assured a prolonged local action, with good skin tolerability among participating individuals. Consequently, these results suggest that PGZ-NE may be used as an alternative treatment for inflammatory skin diseases such as rosacea, atopic dermatitis or psoriasis.

Rosiglitazone remodels the lipid droplet and britens human visceral and subcutaneous adipocytes ex vivo

Treatment with PPARγ agonists in vivo improves human adipocyte metabolism, but the cellular mechanisms and possible depot differences in responsiveness to their effects are poorly understood. To examine the ex vivo metabolic effects of rosiglitazone (Rosi), we cultured explants of human visceral (omental) and abdominal subcutaneous adipose tissues for 7 days. Rosi increased mRNA levels of transcriptional regulators of brite/beige adipocytes (PGC1α, PRDM16), triglyceride synthesis (GPAT3, DGAT1), and lipolysis (ATGL) similarly in adipose tissues from both depots. In parallel, Rosi increased key modulators of FA oxidation (UCP1, FABP3, PLIN5 protein), rates of FA oxidation, and protein levels of electron transport complexes, suggesting an enhanced respiratory capacity as confirmed in newly differentiated adipocytes. Rosi led to the formation of small lipid droplets (SLDs) around the adipocyte central lipid droplet; each SLD was decorated with redistributed mitochondria that colocalized with PLIN5. SLD maintenance required lipolysis and FA reesterification. Rosi thus coordinated a structural and metabolic remodeling in adipocytes from both visceral and subcutaneous depots that enhanced oxidative capacity. Selective targeting of these cellular mechanisms to improve adipocyte FA handling may provide a new approach to treat metabolic complications of obesity and diabetes.

Diabetes and Sepsis: Risk, Recurrence, and Ruination

Sepsis develops when an infection surpasses local tissue containment. A series of dysregulated physiological responses are generated, leading to organ dysfunction and a 10% mortality risk. When patients with sepsis demonstrate elevated serum lactates and require vasopressor therapy to maintain adequate blood pressure in the absence of hypovolemia, they are in septic shock with an in-hospital mortality rate >40%. With improvements in intensive care treatment strategies, overall sepsis mortality has diminished to ~20% at 30 days; however, mortality continues to steadily climb after recovery from the acute event. Traditionally, it was thought that the complex interplay between inflammatory and anti-inflammatory responses led to sepsis-induced organ dysfunction and mortality. However, a closer examination of those who die long after sepsis subsides reveals that many initial survivors succumb to recurrent, nosocomial, and secondary infections. The comorbidly challenged, physiologically frail diabetic individuals suffer the highest infection rates. Recent reports suggest that even after clinical "recovery" from sepsis, persistent alterations in innate and adaptive immune responses exists resulting in chronic inflammation, immune suppression, and bacterial persistence. As sepsis-associated immune defects are associated with increased mortality long-term, a potential exists for immune modulatory therapy to improve patient outcomes. We propose that diabetes causes a functional immune deficiency that directly reduces immune cell function. As a result, patients display diminished bactericidal clearance, increased infectious complications, and protracted sepsis mortality. Considering the substantial expansion of the elderly and obese population, global adoption of a Western diet and lifestyle, and multidrug resistant bacterial emergence and persistence, diabetic mortality from sepsis is predicted to rise dramatically over the next two decades. A better understanding of the underlying diabetic-induced immune cell defects that persist following sepsis are crucial to identify potential therapeutic targets to bolster innate and adaptive immune function, prevent infectious complications, and provide more durable diabetic survival.

Deciphering the Roles of Thiazolidinediones and PPAR in Bladder Cancer

The use of thiazolidinedione (TZD) therapy in type II diabetic patients has proven useful in the lowering of blood glucose levels. However, recent investigations have shown that there may be potential health concerns associated, including the risk of developing bladder cancer as well as complications in the cardiovasculature. TZDs are ligands for the nuclear receptor PPARγ, and activation causes lipid uptake and insulin sensitization, both of which are critical processes for diabetic patients whose bodies are unable to utilize insulin effectively. Several studies have shown that PPARγ/TZDs decrease IGF-1 levels and, thus, reduce cancer growth in carcinomas such as the pancreas, colon, liver, and prostate. However, other studies have shed light on the potential of the receptor as a biomarker for uroepithelial carcinomas, particularly due to its stimulatory effect on migration of bladder cancer cells. Furthermore, PPARγ may provide the tumor-promoting microenvironment by de novo synthesis of nutrients that are needed for bladder cancer development. In this review, we closely examine the TZD class of drugs and their effects on PPARγ in patient studies along with additional molecular factors that are positive modulators, such as protein phosphatase 5 (PP5), which may have considerable implications for bladder cancer therapy.

Mechanisms by which the thiazolidinedione troglitazone protects against sucrose-induced hepatic fat accumulation and hyperinsulinaemia

BACKGROUND AND PURPOSE

Thiazolidinediones (TZD) are known to ameliorate fatty liver in type 2 diabetes. To date, the underlying mechanisms of their hepatic actions remain unclear.

EXPERIMENTAL APPROACH

Hepatic triglyceride content and export rates were assessed in 2 week high-sucrose-fed Wistar rats treated with troglitazone and compared with untreated high-sucrose rodent controls. Fractional de novo lipogenesis (DNL) contributions to hepatic triglyceride were quantified by analysis of triglyceride enrichment from deuterated water. Hepatic insulin clearance and NO status during a meal tolerance test were also evaluated.

KEY RESULTS

TZD significantly reduced hepatic triglyceride (P < 0.01) by 48%, decreased DNL contribution to hepatic triglyceride (P < 0.01) and increased postprandial non-esterified fatty acids clearance rates (P < 0.01) in comparison with the high-sucrose rodent control group. During a meal tolerance test, plasma insulin AUC was significantly lower (P < 0.01), while blood glucose and plasma C-peptide levels were not different. Insulin clearance was increased (P < 0.001) by 24% and was associated with a 22% augmentation of hepatic insulin-degrading enzyme activity (P < 0.05). Finally, hepatic NO was decreased by 24% (P < 0.05).

CONCLUSIONS

Overall, TZD show direct actions on liver by reducing hepatic DNL and increasing hepatic insulin clearance. The alterations in hepatic insulin clearance were associated with changes in insulin-degrading enzyme activity, with possible modulation of NO levels.

Central Regulation of Glucose Production May Be Impaired in Type 2 Diabetes

The challenges of achieving optimal glycemic control in type 2 diabetes highlight the need for new therapies. Inappropriately elevated endogenous glucose production (EGP) is the main source of hyperglycemia in type 2 diabetes. Because activation of central ATP-sensitive potassium (KATP) channels suppresses EGP in nondiabetic rodents and humans, this study examined whether type 2 diabetic humans and rodents retain central regulation of EGP. The KATP channel activator diazoxide was administered in a randomized, placebo-controlled crossover design to eight type 2 diabetic subjects and seven age- and BMI-matched healthy control subjects. Comprehensive measures of glucose turnover and insulin sensitivity were performed during euglycemic pancreatic clamp studies following diazoxide and placebo administration. Complementary rodent clamp studies were performed in Zucker Diabetic Fatty rats. In type 2 diabetic subjects, extrapancreatic KATP channel activation with diazoxide under fixed hormonal conditions failed to suppress EGP, whereas matched control subjects demonstrated a 27% reduction in EGP (P = 0.002) with diazoxide. Diazoxide also failed to suppress EGP in diabetic rats. These results suggest that suppression of EGP by central KATP channel activation may be lost in type 2 diabetes. Restoration of central regulation of glucose metabolism could be a promising therapeutic target to reduce hyperglycemia in type 2 diabetes.

Is the risk of cardiovascular disease altered with anti-inflammatory therapies? Insights from rheumatoid arthritis

Cardiovascular disease (CVD) remains the leading cause of mortality worldwide. Atherosclerosis is the most common form of CVD, which is complex and multifactorial with an elevated risk observed in people with either metabolic or inflammatory diseases. Accumulating evidence now links obesity with a state of chronic low-grade inflammation and has renewed our understanding of this condition and its associated comorbidities. An emerging theme linking disease states with atherosclerosis is the increased production of myeloid cells, which can initiate and exacerbate atherogenesis. Although anti-inflammatory drug treatments exist and have been successfully used to treat inflammatory conditions such as rheumatoid arthritis (RA), a commonly observed side effect is dyslipidemia, inadvertently, a major risk factor for the development of atherosclerosis. The mechanisms leading to dyslipidemia associated with anti-inflammatory drug use and whether CVD risk is actually increased by this dyslipidemia are of great therapeutic importance and currently remain poorly understood. Here we review recent data providing links between inflammation, hematopoiesis, dyslipidemia and CVD risk in the context of anti-inflammatory drug use.

Hypoglycemic agents and potential anti-inflammatory activity

Current literature shows an association of diabetes and secondary complications with chronic inflammation. Evidence of these immunological changes include altered levels of cytokines and chemokines, changes in the numbers and activation states of various leukocyte populations, apoptosis, and fibrosis during diabetes. Therefore, treatment of diabetes and its complications may include pharmacological strategies to reduce inflammation. Apart from anti-inflammatory drugs, various hypoglycemic agents have also been found to reduce inflammation that could contribute to improved outcomes. Extensive studies have been carried out with thiazolidinediones (peroxisome proliferator-activated receptor-γ agonist), dipeptidyl peptidase-4 inhibitors, and metformin (AMP-activated protein kinase activator) with each of these classes of compounds showing moderate-to-strong anti-inflammatory action. Sulfonylureas and alpha glucosidase inhibitors appeared to exert modest effects, while the injectable agents, insulin and glucagon-like peptide-1 receptor agonists, may improve secondary complications due to their anti-inflammatory potential. Currently, there is a lack of clinical data on anti-inflammatory effects of sodium–glucose cotransporter type 2 inhibitors. Nevertheless, for all these glucose-lowering agents, it is essential to distinguish between anti-inflammatory effects resulting from better glucose control and effects related to intrinsic anti-inflammatory actions of the pharmacological class of compounds.

Regulation of metabolism by the innate immune system

Low-grade tissue inflammation induced by obesity can result in insulin resistance, which in turn is a key cause of type 2 diabetes mellitus. Cells of the innate immune system produce cytokines and other factors that impair insulin signalling, which contributes to the connection between obesity and the onset of type 2 diabetes mellitus. Here, we review the innate immune cells involved in secreting inflammatory factors in the obese state. In the adipose tissue, these cells include proinflammatory adipose tissue macrophages and natural killer cells. We also discuss the role of innate immune cells, such as anti-inflammatory adipose tissue macrophages, eosinophils, group 2 innate lymphoid cells and invariant natural killer T cells, in maintaining an anti-inflammatory and insulin-sensitive environment in the lean state. In the liver, both Kupffer cells and recruited hepatic macrophages can contribute to decreased hepatic insulin sensitivity. Proinflammatory macrophages might also adversely affect insulin sensitivity in the skeletal muscle and pancreatic β-cell function. Finally, this Review provides an overview of the mechanisms for regulating proinflammatory immune responses that could lead to future therapeutic opportunities to improve insulin sensitivity.

Obesity: An Immunometabolic Perspective

Obesity, characterized by chronic activation of inflammatory pathways, is a critical factor contributing to insulin resistance (IR) and type 2 diabetes (T2D). Free fatty acids (FFAs) are increased in obesity and are implicated as proximate causes of IR and induction of inflammatory signaling in adipose, liver, muscle, and pancreas. Cells of the innate immune system produce cytokines, and other factors that affect insulin signaling and result in the development of IR. In the lean state, adipose tissue is populated by adipose tissue macrophage of the anti-inflammatory M2 type (ATM2) and natural killer (NK) cells; this maintains the insulin-sensitive phenotype because ATM2 cells secrete IL10. In contrast, obesity induces lipolysis and release of pro-inflammatory FFAs and factors, such as chemokine (C-C motif) ligand 2 (CCL2) and tumor necrosis factor alpha (TNF-α), which recruit blood monocytes in adipose tissue, where they are converted to macrophages of the highly pro-inflammatory M1-type (ATM1). Activated ATM1 produce large amounts of pro-inflammatory mediators such as TNF-α, interleukin-1β, IL-6, leukotriene B4, nitric oxide (NO), and resistin that work in a paracrine fashion and cause IR in adipose tissue. In the liver, both pro-inflammatory Kupffer cells (M1-KCs) and recruited hepatic macrophages (Ly6C^high) contribute to decreased hepatic insulin sensitivity. The present mini-review will update the bidirectional interaction between the immune system and obesity-induced changes in metabolism in adipose tissue and liver and the metabolic consequences thereof.

Pioglitazone in adult rats reverses immediate postnatal overfeeding-induced metabolic, hormonal, and inflammatory alterations

Immediate postnatal overfeeding in rats, obtained by reducing the litter size, results in early-onset obesity. Such experimental paradigm programs overweight, insulin resistance, dyslipidemia, increased adipose glucocorticoid metabolism [up-regulation of glucocorticoid receptor (GR) and 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1)], and overexpression of proinflammatory cytokines in mesenteric adipose tissue (MAT) in adulthood. We studied the effects of pioglitazone, a PPARγ agonist, treatment on the above-mentioned overfeeding-induced alterations. Nine-month-old rats normofed or overfed during the immediate postnatal period were given pioglitazone (3 mg/kg/day) for 6 weeks. Pioglitazone stimulated weight gain and induced a redistribution of adipose tissue toward epididymal location with enhanced plasma adiponectin. Treatment normalized postnatal overfeeding-induced metabolic alterations (increased fasting insulinemia and free fatty acids) and mesenteric overexpression of GR, 11β-HSD11, CD 68, and proinflammatory cytokines mRNAs, including plasminogen-activator inhibitor type 1. Mesenteric GR mRNA levels correlated positively with mesenteric proinflammatory cytokines mRNA concentrations. In vitro incubation of MAT obtained from overfed rats demonstrated that pioglitazone induced a down-regulation of GR gene expression and normalized glucocorticoid-induced stimulation of 11β-HSD1 and plasminogen-activator inhibitor type 1 mRNAs. Our data show for the first time that the metabolic, endocrine, and inflammatory alterations induced by early-onset postnatal obesity can be reversed by pioglitazone at the adulthood. They demonstrate that pioglitazone, in addition to its well-established effect on adipose tissue redistribution and adiponectin secretion, reverses programing-induced adipose GR, 11β-HSD1, and proinflammatory cytokines overexpression, possibly through a GR-dependent mechanism.

Early Clinical Detection of Pharmacologic Response in Insulin Action in a Nondiabetic Insulin-Resistant Population

Background

Insulin resistance heightens the risk for type 2 diabetes mellitus and cardiovascular disease. Amelioration of insulin resistance may reduce this risk. The thiazolidinedone class of insulin sensitizers improves insulin action in individuals with insulin-resistant diabetes and nondiabetic individuals. However, there are few reports on the time of onset of such effects independent of reversal of glucotoxicity.

Objective

The goal of our study was to test whether the thiazolidinedione pioglitazone has prominent early metabolic effects that can be detected in an obese, nondiabetic, insulin-resistant population.

Methods

We conducted a randomized, double-blind, placebo-controlled, parallel-group trial in men with nondiabetic insulin resistance using a hyperinsulinemic euglycemic clamp technique (at low and high doses of insulin at 10 and 40 mU/m²/min, respectively). The patients were given 30 mg daily oral pioglitazone or placebo for 28 days. Patients underwent a baseline clamp before initiation of treatment, and again at 14 and 28 days of treatment.

Results

Compared with placebo, under high-dose hyperinsulinemia, pioglitazone led to significant increases in glucose disposal rates (GDR) of 1.29 mg/kg/min (90% CI, 0.43–2.15; 39%; P=0.008) that were detectable at 2 weeks of treatment and persisted at 4 weeks of treatment. Under low-dose hyperinsulinemia, significant increases in GDR of 0.40 mg/kg/min (90% CI, 0.17–0.62; 95%; P=0.003) were observed at 4 weeks of treatment. These responses were accompanied by robust suppression of free fatty acids under hyperinsulinemic conditions, and by significant increases in circulating basal total adiponectin at 2 and 4 weeks of treatment.

Conclusions

Significant changes in insulin action across multiple insulin-sensitive tissues can be detected within 2 weeks of initiation of insulin-sensitizing therapy with pioglitazone in obese patients with nondiabetic insulin resistance. ClinicalTrials.gov identifier: NCT01115712.

LPSF/GQ-02 inhibits the development of hepatic steatosis and inflammation in a mouse model of non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) defines a wide spectrum of liver diseases that extends from simple steatosis to non-alcoholic steatohepatitis. Although the pathogenesis of NAFLD remains undefined, it is recognized that insulin resistance is present in almost all patients who develop this disease. Thiazolidinediones (TZDs) act as an insulin sensitizer and have been used in the treatment of patients with type 2 diabetes and other insulin-resistant conditions, including NAFLD. Hence, therapy of NAFLD with insulin-sensitizing drugs should ideally improve the key hepatic histological changes, while also reducing cardiometabolic and cancer risks. Controversially, TZDs are associated with the development of cardiovascular events and liver problems. Therefore, there is a need for the development of new therapeutic strategies to improve liver function in patients with chronic liver diseases. The aim of the present study was to assess the therapeutic effects of LPSF/GQ-02 on the liver of LDLR-/- mice after a high-fat diet. Eighty male mice were divided into 4 groups and two different experiments: 1-received a standard diet; 2-fed with a high-fat diet (HFD); 3–HFD+pioglitazone; 4–HFD+LPSF/GQ-02. The experiments were conducted for 10 or 12 weeks and in the last two or four weeks respectively, the drugs were administered daily by gavage. The results obtained with an NAFLD murine model indicated that LPSF/GQ-02 was effective in improving the hepatic architecture, decreasing fat accumulation, reducing the amount of collagen, decreasing inflammation by reducing IL-6, iNOS, COX-2 and F4 / 80, and increasing the protein expression of IκBα, cytoplasmic NFκB-65, eNOS and IRS-1 in mice LDLR -/-. These results suggest a direct action by LPSF/GQ-02 on the factors that affect inflammation, insulin resistance and fat accumulation in the liver of these animals. Further studies are being conducted in our laboratory to investigate the possible mechanism of action of LPSF/GQ-02 on hepatic lipid metabolism.