TNF-alpha inhibits insulin action in liver and adipose tissue: A model of metabolic syndrome

GPR40 deficiency worsens metabolic syndrome-associated periodontitis in mice

BACKGROUND AND OBJECTIVE

G protein-coupled receptor 40 (GPR40) is a receptor for medium- and long-chain free fatty acids (FFAs). GPR40 activation improves type 2 diabetes mellitus (T2DM), metabolic syndrome (MetS), and the complications of T2DM and MetS. Periodontitis, a common oral inflammatory disease initiated by periodontal pathogens, is another complication of T2DM and MetS. Since FFAs play a key role in the pathogenesis of MetS which exacerbates periodontal inflammation and GPR40 is a FFA receptor with anti-inflammatory properties, it is important to define the role of GPR40 in MetS-associated periodontitis.

MATERIALS AND METHODS

We induced MetS and periodontitis by high-fat diet and periodontal injection of lipopolysaccharide (LPS), respectively, in wild-type and GPR40-deficient mice and determined alveolar bone loss and periodontal inflammation using micro-computed tomography, histology, and osteoclast staining. We also performed in vitro study to determine the role of GPR40 in the expression of proinflammatory genes.

RESULTS

The primary outcome of the study is that GPR40 deficiency increased alveolar bone loss and enhanced osteoclastogenesis in control mice and the mice with both MetS and periodontitis. GPR40 deficiency also augmented periodontal inflammation in control mice and the mice with both MetS and periodontitis. Furthermore, GPR40 deficiency led to increased plasma lipids and insulin resistance in control mice but had no effect on the metabolic parameters in mice with MetS alone. For mice with both MetS and periodontitis, GPR40 deficiency increased insulin resistance. Finally, in vitro studies with macrophages showed that deficiency or inhibition of GPR40 upregulated proinflammatory genes while activation of GPR40 downregulated proinflammatory gene expression stimulated synergistically by LPS and palmitic acid.

CONCLUSION

GPR40 deficiency worsens alveolar bone loss and periodontal inflammation in mice with both periodontitis and MetS, suggesting that GPR40 plays a favorable role in MetS-associated periodontitis. Furthermore, GPR40 deficiency or inhibition in macrophages further upregulated proinflammatory and pro-osteoclastogenic genes induced by LPS and palmitic acid, suggesting that GPR40 has anti-inflammatory and anti-osteoclastogenic properties.

Is TNF alpha a mediator in the co-existence of malaria and type 2 diabetes in a malaria endemic population?

Malaria remains a disease of public health importance globally, especially in sub-Saharan Africa. Malaria deaths reduced globally steadily between 2000-2019, however there was a 10% increase in 2020 due to disruptions in medical service during the COVID-19 pandemic. Globally, about 96% of malaria deaths occurred in 29 countries; out of which, four countries (Nigeria, the Democratic Republic of the Congo, the Niger, and the United Republic of Tanzania) accounted for just over half of the malaria deaths. Nigeria leads the four countries with the highest malaria deaths (accounting for 31% globally). Parallelly, sub-Saharan Africa is faced with a rise in the incidence of Type 2 diabetes (T2D). Until recently, T2D was a disease of adulthood and old age. However, this is changing as T2D in children and adolescents is becoming an increasingly important public health problem. Nigeria has been reported to have the highest burden of diabetes in Africa with a prevalence of 5.77% in the country. Several studies conducted in the last decade investigating the interaction between malaria and T2D in developing countries have led to the emergence of the intra-uterine hypothesis. The hypothesis has arisen as a possible explanation for the rise of T2D in malaria endemic areas; malaria in pregnancy could lead to intra-uterine stress which could contribute to low birth weight and may be a potential cause of T2D later in life. Hence, previous, and continuous exposure to malaria infection leads to a higher risk of T2D. Current and emerging evidence suggests that an inflammation-mediated link exists between malaria and eventual T2D emergence. The inflammatory process thus, is an important link for the co-existence of malaria and T2D because these two diseases are inflammatory-related. A key feature of T2D is systemic inflammation, characterized by the upregulation of inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) which leads to impaired insulin signaling. Malaria infection is an inflammatory disease in which TNF-α also plays a major role. TNF-α plays an important role in the pathogenesis and development of malaria and T2D. We therefore hypothesize that TNF-α is an important link in the increasing co-existence of T2D.

The Plasma Levels of 3-Hydroxybutyrate, Dityrosine, and Other Markers of Oxidative Stress and Energy Metabolism in Major Depressive Disorder

Major depressive disorder (MDD) is a serious mental disease with a pathophysiology that is not yet fully clarified. An increasing number of studies show an association of MDD with energy metabolism alteration and the presence of oxidative stress. We aimed to evaluate plasma levels of 3-hydroxybutyrate (3HB), NADH, myeloperoxidase, and dityrosine (di-Tyr) in adolescent and adult patients with MDD, compare them with healthy age-matched controls, and assess the effect of antidepressant treatment during hospitalisation on these levels. In our study, plasmatic levels of 3HB were elevated in both adolescents (by 55%; p = 0.0004) and adults (by 88%; p < 0.0001) with MDD compared to controls. Levels of dityrosine were increased in MDD adults (by 19%; p = 0.0092) but not adolescents. We have not found any significant effect of antidepressants on the selected parameters during the short observation period. Our study supports the findings suggesting altered energy metabolism in MDD and demonstrates its presence independently of the age of the patients.

Hepatic Gadd45β promotes hyperglycemia and glucose intolerance through DNA demethylation of PGC-1α

Although widely used for their potent anti-inflammatory and immunosuppressive properties, the prescription of glucocorticoid analogues (e.g., dexamethasone) has been associated with deleterious glucose metabolism, compromising their long-term therapeutic use. However, the molecular mechanism remains poorly understood. In the present study, through transcriptomic and epigenomic analysis of two mouse models, we identified a growth arrest and DNA damage-inducible β (Gadd45β)-dependent pathway that stimulates hepatic glucose production (HGP). Functional studies showed that overexpression of Gadd45β in vivo or in cultured hepatocytes activates gluconeogenesis and increases HGP. In contrast, liver-specific Gadd45β-knockout mice were resistant to high-fat diet- or steroid-induced hyperglycemia. Of pathophysiological significance, hepatic Gadd45β expression is up-regulated in several mouse models of obesity and diabetic patients. Mechanistically, Gadd45β promotes DNA demethylation of PGC-1α promoter in conjunction with TET1, thereby stimulating PGC-1α expression to promote gluconeogenesis and hyperglycemia. Collectively, these findings unveil an epigenomic signature involving Gadd45β/TET1/DNA demethylation in hepatic glucose metabolism, enabling the identification of pathogenic factors in diabetes.

Impact of tumor necrosis factor inhibitors and methotrexate on diabetes mellitus among patients with inflammatory arthritis

Background

To determine whether initiation of a tumor necrosis factor inhibitor (TNFi) or methotrexate improves hemoglobin A1c in patients with psoriatic arthritis (PsA), rheumatoid arthritis (RA), or ankylosing spondylitis (AS) who also have diabetes mellitus (DM).

Methods

A retrospective cohort study was conducted in Optum's de-identified Clinformatics® Data Mart Database, an administrative claims database, using data from 2000 to 2014. Patients with PsA, RA, or AS, with DM (defined by ICD-9-CM codes) and/or HbA1c ≥7%, who newly initiated either a TNFi, MTX, or metformin (positive control) were identified. The change in HbA1c after drug initiation was calculated. Statistical differences in the change in HbA1c between drugs were assessed using the Wilcoxon rank sum test and linear regression models adjusting for potential confounders.

Results

Among 10,389 drug initiations in 9541 patients with PsA, RA, or AS, and available HbA1c values, HbA1c was ≥7 at baseline in 254 (35%) TNFi initiations, 361(37%) MTX initiations, and 2144 (50%) metformin initiations. Median HbA1c change was - 0.35 (IQR -1.10, 0.30) after TNFi initiation, - 0.40 (IQR -1.20, 0.30) after MTX initiation, and - 0.80 (IQR -1.60, - 0.10) after metformin initiation. In adjusted analyses, TNFi initiators had less of a decrease in HbA1c compared to MTX initiators (β 0.22, 95% CI: 0.004, 0.43), p = 0.046. Metformin initiators had a significantly greater decrease in HbA1c than MTX, β - 0.38 (95% CI: - 0.52, - 0.23), p < 0.001. Glucocorticoid use was not accounted for in the models.

Conclusion

HbA1c decreased with TNFi initiation or MTX initiation. Reductions in HbA1c after initiation of a TNFi or MTX are about half (~ 0.4 units) the decrease observed after initiation of metformin.

Inflammation, insulin resistance and neuroprogression in depression

Chronic low-grade inflammation has been observed in major depression and other major psychiatric disorders and has been implicated in metabolic changes that are commonly associated with these disorders. This raises the possibility that the effects of dysfunctional metabolism may facilitate changes in neuronal structure and function which contribute to neuroprogression. Such changes may have implications for the progress from major depression to dementia in the elderly patient. The purpose of this review is to examine the contribution of inflammation and hypercortisolaemia, which are frequently associated with major depression, to neurodegeneration and how they detrimentally impact on brain energy metabolism. A key factor in these adverse events is insulin insensitivity caused by pro-inflammatory cytokines in association with desensitised glucocorticoid receptors. Identifying the possible metabolic changes initiated by inflammation opens new targets to ameliorate the adverse metabolic changes. This has resulted in the identification of dietary and drug targets which are of interest in the development of a new generation of psychotropic drugs.

Molecular and Pathological Events Involved in the Pathogenesis of Diabetes-Associated Nonalcoholic Fatty Liver Disease

Diabetes mellitus is a rising epidemic in most part of the world and is often associated with multiple organ disorders such as kidney, liver, and cardiovascular diseases. Liver is a major metabolic hub, and the metabolic disorders associated with diabetes result in liver dysfunctions culminating in spectrum of liver diseases such as fatty liver disorders, cirrhosis, and hepatocellular carcinoma. The intervention strategies to prevent diabetes-associated liver injury require an overall understanding of the key factors and molecular pathways which can be strategically targeted. The present review focuses on some of the key aspects of fatty acid metabolism, fetuin-A regulation, inflammatory pathways, and genetic factors associated with insulin resistance, dyslipidemia, hyperglycemia, oxidative stress, and so on involved in the nexus between diabetes and liver injury. Further recent interventions, pharmacological target, and newer therapeutic agents are discussed briefly for the better clinical management of diabetes-associated hepatic disorders.

Metformin Associated With Increased Survival in Type 2 Diabetes Patients With Pancreatic Cancer and Lymphoma

BACKGROUND

The biguanide drug metformin is one of the most commonly used medications for the treatment of type 2 diabetes mellitus. Diabetics are at an increased risk for cancer. Previous studies have demonstrated improved outcomes in patients taking metformin suffering from prostate, colon, lung, thyroid, and esophageal cancers. Metformin's main antineoplastic mechanism of action is thought to be mediated through inhibition of mammalian target of rapamycin, inhibition of hypoxia-inducible factor 1 (HIF-1) alpha, and activation of p53. We investigated the overall survival of type 2 diabetic patients on metformin with pancreatic cancer and lymphoma using the Computerized Patient Record System at the Veterans Affairs Medical Center, Memphis TN.

METHODS

Lymphoma and pancreatic cancer patients with type 2 diabetes were sorted into an experimental (metformin) group and a control (nonmetformin) group. Patients were compared on baseline characteristics including race, body mass index, and age. Cancer outcomes including overall survival, metastasis, recurrences, and incidence of new malignancies were recorded. Hemoglobin A1C, creatinine and cancer treatment modalities were recorded and compared. Statistical analyses used included unpaired t tests and Chi-squared tests.

RESULTS

There was significantly greater overall long-term survival in the metformin group compared to the nonmetformin group for lymphoma (5.89 vs 1.29 years, P < 0.001) and for pancreatic cancer (0.68 vs 0.22 years, P = 0.016). Cancer treatment modalities in both groups were comparable.

CONCLUSIONS

Metformin is associated with a significant, positive effect of increased overall survival in type 2 diabetes patients with pancreatic cancer and lymphoma. These results are encouraging, and prospective studies should be done to further investigate metformin's effects in cancer.

Diabetes Mellitus Prevents an Improvement in the Serum Albumin Level During Interferon-free Sofosbuvir-based Therapy for Chronic Hepatitis C Patients: A Multi-institutional Joint Study

Objective Interferon-free regimens of direct-acting antiviral agents have improved the treatment response for chronic hepatitis C virus (HCV) infection, and improvement in the serum albumin level during interferon-free therapy has been reported. The aim of this study was to identify the factors that influence the improvement in the serum albumin level in patients receiving interferon-free antiviral therapy. Methods This retrospective, multicenter study consisted of 471 Japanese patients with chronic hepatitis and compensated liver cirrhosis infected with HCV who completed 12-week interferon-free sofosbuvir (SOF)-based therapy [SOF plus ledipasvir for genotype 1 (n=276) and SOF with ribavirin for genotype 2 (n=195)]. We evaluated the changes in the serum albumin level from baseline to the end of treatment (ΔAlb). Results When compared with the normal-albumin group (baseline serum albumin >35 g/L, n=406), the low-albumin group (baseline serum albumin ≤35 g/L, n=65) showed a significant increase in the mean ΔAlb (5.5 g/L vs. 1.0 g/L, p<0.001). In the low-albumin group, a multivariate logistic regression analysis extracted diabetes mellitus as a negative predictive factor of median ΔAlb >5.0 g/L (odds ratio: 0.19, 95% confidence interval: 0.048-0.79, p=0.020). In the low-albumin group, the mean ΔAlb was significantly lower in the diabetic patients (n=14) than in the non-diabetic patients (n=51) (3.9 g/L and 5.7 g/L, p=0.049). Conclusion Interferon-free SOF-based therapy significantly improved the serum albumin in the low-albumin group patients with chronic HCV infection. However, the improvement in the serum albumin level was significantly lower in the diabetic patients than in the non-diabetic patients.

Naringenin improve hepatitis C virus infection induced insulin resistance by increase PTEN expression via p53-dependent manner

Hepatitis C virus (HCV) infection may finally lead to hepatocellular carcinoma (HCC), and also associated with insulin resistance (IR). Naringenin (NGEN), a flavonoid found in grapefruit, has anti-virus, anti-inflammation and insulin sensitization effects. In the present study we examined the effects of NGEN on HCV core protein (HCVCP) infection induced IR and investigated the mechanism involved. We found that NGEN ameliorated IR and glucose tolerance in HCVCP infected mice by increase the phosphorylation of Akt at both Ser473 and Thr308 site, and also inhibited the inflammation cytokine production and T-cell immune response. Similar to the in vivo results, NGEN also improved the insulin response and showed anti-inflammation effect in HCVCP infected Huh-7.5.1 cells. In addition, NGEN up-regulated the phosphatase and tensin homolog deleted on chromosome ten (PTEN) both in protein and mRNA levels. Furthermore, overexpress of PTEN abolished the HCVCP-stimulated IR and decreased the inflammation cytokine release. NGEN also blocked the interaction between HCVCP and p53, upregulated the endogenous p21/waf1 expression which indiacting the activation of p53. The p53 wild type could upregulate NGEN-stimulated PTEN expression while R273H mut-p53 showed no similar function. Our data reveals that NGEN increases insulin sensitivity in HCVCP infected liver by up-regulating PTEN in p53-dependent manner.

Favorable Effect of Anti-TNF Therapy on Insulin Sensitivity in Nonobese, Nondiabetic Patients with Inflammatory Bowel Disease

BACKGROUND

The aim of this study was to investigate the effect of anti-TNF therapy on glucose and lipid metabolism in nondiabetic, nonobese patients with inflammatory bowel disease (IBD).

PATIENTS AND METHODS

We studied 44 patients with IBD, without a known history of diabetes. Three of the patients were diagnosed with overt diabetes and were excluded. Eighteen of the remaining patients (9 M/9 F, 33.6 ± 8.8 years) were on anti-TNF therapy for longer than 1 year, while 23 patients (16 M/7 F, 38.7 ± 12.5 years) were treated with aminosalicylates (AMSs). Twelve of the patients from the second group were then treated with anti-TNF and reassessed 6 months later. Fasting glucose, insulin, c-peptide, HbA1c, lipid, CRP, and fibrinogen levels were determined, and HOMA-IR index was calculated in all patients.

RESULTS

Patients from the two therapy groups were matched for age and BMI and were not obese. We did not find any differences between patients from the two therapy groups regarding fasting glucose, c-peptide, HbA1c, total cholesterol, HDL, LDL, triglycerides, CRP, and HOMA-IR index. In patients who were treated for 6 months with anti-TNF, a statistically significant decrease in insulin (before 15.5 ± 5.9 versus after 9.9 ± 2.9 μIU/ml, p = 0.042) and c-peptide (before 2.4 ± 1 versus after 1.3 ± 0.4 ng/ml, p = 0.030) levels as well as the HOMA-IR index (before 4.2 ± 1.9 versus after 2.2 ± 0.9, p = 0.045) was observed, without any changes in weight, BMI, glucose, HbA1c, lipid, CRP, and fibrinogen levels.

CONCLUSION

Anti-TNF therapy exerts a favorable effect on insulin sensitivity, while it has no effect on lipid levels in nondiabetic, nonobese patients with inflammatory bowel disease.

Tumor Necrosis Factor-Alpha: Role in Development of Insulin Resistance and Pathogenesis of Type 2 Diabetes Mellitus

Pathogenesis of type 2 diabetes mellitus (T2DM) and development of insulin resistance are characterized by multi-stimuli factors notably glucolipotoxicity, generation of reactive oxygen species (ROS), epigenetic factors, activation of various transcriptional mediated pathways along with the augmented levels of various pro-inflammatory cytokines. Among the various pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) is one the most important pro-inflammatory mediator that is critically involved in the development of insulin resistance and pathogenesis of T2DM. TNF-α is mainly produced in adipocytes and/or peripheral tissues, and induces tissue-specific inflammation through the involvement of generation of ROS and activation of various transcriptional mediated pathways. The raised level of TNF-α induces insulin resistance in adipocytes and peripheral tissues by impairing the insulin signaling through serine phosphorylation that leads to the development of T2DM. Anti-TNF-α treatment strategies have been developed to reduce the incidence of insulin resistance and development of T2DM. In this article, we have briefly described how TNF-α plays crucial role to induce insulin resistance and pathogenesis of T2DM. To block the inflammatory responses by blocking TNF-α and TNF-α signaling may be an effective strategy for the treatment of insulin resistance and T2DM. J. Cell. Biochem. 119: 105-110, 2018. © 2017 Wiley Periodicals, Inc.

Insulin attenuates TNFα-induced hemopexin mRNA: An anti-inflammatory action of insulin in rat H4IIE hepatoma cells

Proinflammatory cytokines, including TNF-α and IL-6, can contribute to insulin resistance. Conversely, insulin has some actions that can be considered anti-inflammatory. Hemopexin is a Class 2 acute phase reactant and control of its transcription is predominantly regulated by IL-6, with TNF-α and IL-1β also inducing hemopexin gene expression. Thus, we asked whether insulin could inhibit the ability of TNF-α to stimulate hemopexin mRNA expression. In cultured rat hepatoma (H4IIE) cells, TNF-α significantly increased hemopexin mRNA accumulation. The TNF-α-induced increase of hemopexin mRNA was dramatically attenuated by insulin, even though TNF-α reduced peak insulin activation of ERK. Thus, even though TNF-α can contribute to insulin resistance, the residual insulin response was still able to counteract TNF-α actions.

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The TNF-α-induced increase of hemopexin mRNA was dramatically attenuated by insulin.

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This occurred even though TNF-α significantly decreased insulin activation of ERK.

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This suggests an additional mechanism for the anti-inflammatory action of insulin.

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Cytokine-induced insulin resistance does not abolish insulin’s anti-inflammatory effect.

[Ovarian reserve and adipokine levels in reproductive-aged obese women]

AIM

To investigate the relationship of the ovarian reserve to the levels of adipokines and sex hormones in reproductive-aged women with abdominal obesity.

SUBJECTS AND METHODS

A total of 157 women aged 18 to 45 years with a body mass index (BMI) of more than 30 kg/m2 were examined (a study group). A control group consisted of 93 women aged 18-45 years with a BMI of less than 25 kg/m2. Anthropometric and carbohydrate and lipid metabolic parameters and the levels of sex hormones, anti-Müllerian hormone, resistin, and adiponectin were investigated.

RESULTS

The mean age of the participants with a BMI of more than 30 kg/m2 was 33.1±6.1 years and that of those with a BMI of less than 25-30 kg/m2 was 32.8±6.2 years. No statistically significant differences were found in age, ethnicity, and marital status between the participants of both groups; however, there was a statistically significant difference in education levels - 76.3% of the women with a BMI of less than 25 kg/m2 (p<0.0001) had higher education. The obese patients were found to have a statistically significant increase in the levels of insulin, HOMA-IR, glucose, total cholesterol, low-density lipoproteins, thyrotrophic hormone, testosterone, and resistin and a decrease in those of high-density lipoproteins, adiponectin, and anti-Müllerian hormone. Comparative analysis made in the obese patients revealed that there was a statistically significant correlation of anti-Müllerian hormone values and hormonal status with the levels of follicle-stimulating hormone (p=0.0026) and resistin (p=0.0323).

CONCLUSION

The ovarian reserve decreases and the processes of reproductive system aging accelerate in reproductive-aged women with abdominal obesity in the presence of insulin resistance and hyperinsulinemia.

TNF-α induces vascular insulin resistance via positive modulation of PTEN and decreased Akt/eNOS/NO signaling in high fat diet-fed mice

BACKGROUND

High fat diet (HFD) induces insulin resistance in various tissues, including the vasculature. HFD also increases plasma levels of TNF-α, a cytokine that contributes to insulin resistance and vascular dysfunction. Considering that the enzyme phosphatase and tension homologue (PTEN), whose expression is increased by TNF-α, reduces Akt signaling and, consequently, nitric oxide (NO) production, we hypothesized that PTEN contributes to TNF-α-mediated vascular resistance to insulin induced by HFD. Mechanisms underlying PTEN effects were determined.

METHODS

Mesenteric vascular beds were isolated from C57Bl/6J and TNF-α KO mice submitted to control or HFD diet for 18 weeks to assess molecular mechanisms by which TNF-α and PTEN contribute to vascular dysfunction.

RESULTS

Vasodilation in response to insulin was decreased in HFD-fed mice and in ex vivo control arteries incubated with TNF-α. TNF-α receptors deficiency and TNF-α blockade with infliximab abolished the effects of HFD and TNF-α on insulin-induced vasodilation. PTEN vascular expression (total and phosphorylated isoforms) was increased in HFD-fed mice. Treatment with a PTEN inhibitor improved insulin-induced vasodilation in HFD-fed mice. TNF-α receptor deletion restored PTEN expression/activity and Akt/eNOS/NO signaling in HFD-fed mice.

CONCLUSION

TNF-α induces vascular insulin resistance by mechanisms that involve positive modulation of PTEN and inhibition of Akt/eNOS/NO signaling. Our findings highlight TNF-α and PTEN as potential targets to limit insulin resistance and vascular complications associated with obesity-related conditions.

Role of stem cells during diabetic liver injury

Diabetes mellitus is one of the most severe endocrine metabolic disorders in the world that has serious medical consequences with substantial impacts on the quality of life. Type 2 diabetes is one of the main causes of diabetic liver diseases with the most common being non-alcoholic fatty liver disease. Several factors that may explain the mechanisms related to pathological and functional changes of diabetic liver injury include: insulin resistance, oxidative stress and endoplasmic reticulum stress. The realization that these factors are important in hepatocyte damage and lack of donor livers has led to studies concentrating on the role of stem cells (SCs) in the prevention and treatment of liver injury. Possible avenues that the application of SCs may improve liver injury include but are not limited to: the ability to differentiate into pancreatic β-cells (insulin producing cells), the contribution for hepatocyte regeneration, regulation of lipogenesis, glucogenesis and anti-inflammatory actions. Once further studies are performed to explore the underlying protective mechanisms of SCs and the advantages and disadvantages of its application, there will be a greater understand of the mechanism and therapeutic potential. In this review, we summarize the findings regarding the role of SCs in diabetic liver diseases.

Role of PTEN in TNFα induced insulin resistance

AIMS/HYPOTHESIS

PTEN may play a reversible role in TNFα induced insulin resistance, which has been linked to obesity-associated insulin resistance (IR).

METHODS

Western blots for PTEN and p-Akt were performed on H-411E liver cells incubated with insulin, TNFα, and in selected experiments VO-OHpic vanadium complex in the presence and absence of PTEN siRNA. Total PTEN was compared to β-actin loading control and p-Akt was compared to total Akt.

RESULTS

Western blot and Real Time RT-PCR experiments showed increased PTEN after TNFα treatment (p = 0.04); slightly decreased PTEN after insulin treatment; and slightly increased PTEN after insulin + TNFα treatment. PTEN siRNA markedly inhibited the TNFα-induced increase in PTEN (p < 0.01) without significantly changing the p-Akt levels. The vanadium complex, exhibiting insulin-like effects, also significantly prevented the TNFα-induced increase in PTEN. Combining insulin and VO-OHpic was additive, providing both proof of concept and insight into mechanism.

DISCUSSION

The PTEN increase due to TNFα treatment was reversible by both PTEN siRNA knockdown and VO-OHpic treatment. Thus, PTEN is identified as a potential new therapeutic target for reducing IR in Type 2 DM.

Efficacy and safety of ginsam, a vinegar extract from Panax ginseng, in type 2 diabetic patients: Results of a double-blind, placebo-controlled study

Aims/Introduction:  The efficacy, dose–response relationship and safety of ginsam, a vinegar extract from Panax ginseng, were evaluated in an 8‐week, double‐blind, randomized, placebo‐controlled study in drug‐naïve patients with type 2 diabetes.

Materials and Methods:  A total of 72 diabetic patients were randomized to receive 1500, 2000 or 3000 mg of ginsam, or placebo daily for 8 weeks (n = 18 in each group). The primary end‐point was the changes from the baseline HbA_1c level. The secondary end‐points were the changes of fasting and postprandial 2‐h glucose concentration, and the proportion of patients achieving a reduction in HbA_1c >0.5%.

Results:  In the intention‐to‐treat analysis, ginsam treatment reduced HbA_1c level significantly: −0.56 ± 0.25% in the 1500 mg group, −0.31 ± 0.12% in the 2000 mg group, and −0.29 ± 0.11% in the 3000 mg group (all P < 0.05), with a significant difference between the 1500 mg ginsam and the placebo group (−0.02 ± 0.12%, P = 0.021). The changes in fasting glucose concentration followed the same pattern: −21.40, −14.27 and −6.76 mg/dL for 1500, 2000, and 3000 mg, respectively, vs −2.25 mg/dL for the placebo. The percentage of patients whose HbA_1c level decreased by >0.5% differed significantly between the placebo group (11.1%) and the 1500 mg (27.8%) and 2000 mg (27.8%) groups. No severe adverse events were observed in any group.

Conclusions:  An 8‐week treatment with ginsam, a vinegar extract from P. ginseng, moderately improved HbA_1c level and was well tolerated in type 2 diabetic patients with inadequate glycemic control. This trial was registered with ClinicalTrial.Gov (no. NCT01008163). (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00185.x, 2011)

Mesenchymal stem cell therapy ameliorates diabetic hepatocyte damage in mice by inhibiting infiltration of bone marrow-derived cells

Although mesenchymal stem cells (MSCs) have been implicated in hepatic injury, the mechanism through which they contribute to diabetic liver disease has not been clarified. In this study, we investigated the effects of MSC therapy on diabetic liver damage with a focus on the role of bone-marrow-derived cells (BMDCs), which infiltrate the liver, and elucidated the mechanism mediating this process. Rat bone-marrow (BM)-derived MSCs were administered to high-fat diet (HFD)-induced type 2 diabetic mice and streptozotocin (STZ)-induced insulin-deficient diabetic mice. MSC-conditioned medium (MSC-CM) was also administered to examine the trophic effects of MSCs on liver damage. Therapeutic effects of MSCs were analyzed by assessing serum liver enzyme levels and histological findings. Kinetic and molecular profiles of BMDCs in the liver were evaluated using BM-chimeric mice. Curative effects of MSC and MSC-CM therapies were similar because both ameliorated the aggravation of aspartate aminotransferase and alanine aminotransferase at 8 weeks of treatment, despite persistent hyperlipidemia and hyperinsulinemia in HFD-diabetic mice and persistent hyperglycemia in STZ-diabetic mice. Furthermore, both therapies suppressed the abnormal infiltration of BMDCs into the liver, reversed excessive expression of proinflammatory cytokines in parenchymal cells, and regulated proliferation and survival signaling in the liver in both HFD- and STZ-diabetic mice. In addition to inducing hepatocyte regeneration in STZ-diabetic mice, both therapies also prevented excessive lipid accumulation and apoptosis of hepatocytes and reversed insulin resistance (IR) in HFD-diabetic mice.

CONCLUSION

MSC therapy is a powerful tool for repairing diabetic hepatocyte damage by inhibiting inflammatory reactions induced by BMDCs and IR. These effects are likely the result of humoral factors derived from MSCs.

Factors affecting insulin-regulated hepatic gene expression

Obesity has become a major concern of public health. A common feature of obesity and related metabolic disorders such as noninsulin-dependent diabetes mellitus is insulin resistance, wherein a given amount of insulin produces less than normal physiological responses. Insulin controls hepatic glucose and fatty acid metabolism, at least in part, via the regulation of gene expression. When the liver is insulin-sensitive, insulin can stimulate the expression of genes for fatty acid synthesis and suppress those for gluconeogenesis. When the liver becomes insulin-resistant, the insulin-mediated suppression of gluconeogenic gene expression is lost, whereas the induction of fatty acid synthetic gene expression remains intact. In the past two decades, the mechanisms of insulin-regulated hepatic gene expression have been studied extensively and many components of insulin signal transduction pathways have been identified. Factors that alter these pathways, and the insulin-regulated hepatic gene expression, have been revealed and the underlying mechanisms have been proposed. This chapter summarizes the recent progresses in our understanding of the effects of dietary factors, drugs, bioactive compounds, hormones, and cytokines on insulin-regulated hepatic gene expression. Given the large amount of information and progresses regarding the roles of insulin, this chapter focuses on findings in the liver and hepatocytes and not those described for other tissues and cells. Typical insulin-regulated hepatic genes, such as insulin-induced glucokinase and sterol regulatory element-binding protein-1c and insulin-suppressed cytosolic phosphoenolpyruvate carboxyl kinase and insulin-like growth factor-binding protein 1, are used as examples to discuss the mechanisms such as insulin regulatory element-mediated transcriptional regulation. We also propose the potential mechanisms by which these factors affect insulin-regulated hepatic gene expression and discuss potential future directions of the area of research.

Experimental evidence for the use of CCR2 antagonists in the treatment of type 2 diabetes

OBJECTIVE

CCR2 inhibition has produced promising experimental and clinical anti-hyperglycemic effects. These results support the thesis that insulin resistance and Type 2 diabetes (T2D) are associated with chronic unresolved inflammation. The aim of this study was to provide a broad analysis of the various physiological changes occurring in mouse models of T2D in connection with pharmacological CCR2 inhibition.

MATERIALS/METHODS

A mouse-active chemical analogue of the clinical candidate CCX140-B was tested in diet-induced obese (DIO) mice and db/db mice. Measurements included: adipose tissue inflammatory macrophage counts; peripheral blood glucose levels at steady-state and after glucose and insulin challenges; peripheral blood insulin and adiponectin levels; 24-h urine output and urinary glucose levels; pancreatic islet number and size; hepatic triglyceride and glycogen content; and hepatic glucose-6-phosphatase levels.

RESULTS

In DIO mice, the CCR2 antagonist completely blocked the recruitment of inflammatory macrophages to visceral adipose tissue. The mice exhibited reduced hyperglycemia and insulinemia, improved insulin sensitivity, increased circulating adiponectin levels, decreased pancreatic islet size and increased islet number. It also reduced urine output, glucose excretion, hepatic glycogen and triglyceride content and glucose 6-phosphatase levels. Similar effects were observed in the db/db diabetic mice.

CONCLUSIONS

These data indicate that pharmacological inhibition of CCR2 in models of T2D can reduce inflammation in adipose tissue, alter hepatic metabolism and ameliorate multiple diabetic parameters. These mechanisms may contribute to the promising anti-diabetic effects seen in humans with at least one CCR2 antagonist.

Acute psychological stress results in the rapid development of insulin resistance

In recent years, the roles of chronic stress and depression as independent risk factors for decreased insulin sensitivity and the development of diabetes have been increasingly recognized. However, an understanding of the mechanisms linking insulin resistance and acute psychological stress are very limited. We hypothesized that acute psychological stress may cause the development of insulin resistance, which may be a risk factor in developing type 2 diabetes. We tested the hypothesis in a well-established mouse model using 180 episodes of inescapable foot shock (IES) followed by a behavioral escape test. In this study, mice that received IES treatment were tested for acute insulin resistance by measuring glucose metabolism and insulin signaling. When compared with normal and sham mice, mice that were exposed to IES resulting in escape failure (defined as IES with behavioral escape failure) displayed elevated blood glucose levels in both glucose tolerance and insulin tolerance tests. Furthermore, mice with IES exposure and behavioral escape failure exhibited impaired hepatic insulin signaling via the insulin-induced insulin receptor/insulin receptor substrate 1/Akt pathway, without affecting similar pathways in skeletal muscle, adipose tissue, and brain. Additionally, a rise in the murine growth-related oncogene KC/GRO was associated with impaired glucose metabolism in IES mice, suggesting a mechanism by which psychological stress by IES may influence glucose metabolism. The present results indicate that psychological stress induced by IES can acutely alter hepatic responsiveness to insulin and affect whole-body glucose metabolism.

An overview of the contribution of fatness and fitness factors, and the role of exercise, in the formation of health status for individuals who are overweight

Over the last half century there has been an epidemic of diminished health status induced by what seems as a concurrent rise in a population of individuals that are overfat. During the past few decades, the use of exercise has become a staple in the prevention and treatment options for the retarding the development of health issues pertaining to individuals who are overweight, overfatness or experience obesity. However, there are few studies and reviews look at the global issues surrounding the metabolic and hormone consequences of overfatness and the interaction of exercise with adiposity in humans developing the health status for the individual. This review offers an insight into our current understanding of health issues pertaining to metabolic and hormonal disruption related to overfatness and the treatment effect that exercise, especially resistance exercise, can have on impacting the health status, and overall well-being, for individuals who are overfat, regardless of body compositional changes leading toward a lessening of diseased state, and eventually a return to a normal health status for the individual.

Breaking patterns of environmentally influenced disease for health risk reduction: immune perspectives

BACKGROUND

Diseases rarely, if ever, occur in isolation. Instead, most represent part of a more complex web or "pattern" of conditions that are connected via underlying biological mechanisms and processes, emerge across a lifetime, and have been identified with the aid of large medical databases.

OBJECTIVE

We have described how an understanding of patterns of disease may be used to develop new strategies for reducing the prevalence and risk of major immune-based illnesses and diseases influenced by environmental stimuli.

FINDINGS

Examples of recently defined patterns of diseases that begin in childhood include not only metabolic syndrome, with its characteristics of inflammatory dysregulation, but also allergic, autoimmune, recurrent infection, and other inflammatory patterns of disease. The recent identification of major immune-based disease patterns beginning in childhood suggests that the immune system may play an even more important role in determining health status and health care needs across a lifetime than was previously understood.

CONCLUSIONS

Focusing on patterns of disease, as opposed to individual conditions, offers two important venues for environmental health risk reduction. First, prevention of developmental immunotoxicity and pediatric immune dysfunction can be used to act against multiple diseases. Second, pattern-based treatment of entryway diseases can be tailored with the aim of disrupting the entire disease pattern and reducing the risk of later-life illnesses connected to underlying immune dysfunction. Disease-pattern-based evaluation, prevention, and treatment will require a change from the current approach for both immune safety testing and pediatric disease management.