Cardiotrophin 1 protects beta cells from apoptosis and prevents streptozotocin-induced diabetes in a mouse model

Potential clinical biomarkers and perspectives in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a serious cardiovascular complication and the leading cause of death in diabetic patients. Patients typically do not experience any symptoms and have normal systolic and diastolic cardiac functions in the early stages of DCM. Because the majority of cardiac tissue has already been destroyed by the time DCM is detected, research must be conducted on biomarkers for early DCM, early diagnosis of DCM patients, and early symptomatic management to minimize mortality rates among DCM patients. Most of the existing implemented clinical markers are not very specific for DCM, especially in the early stages of DCM. Recent studies have shown that a number of new novel markers, such as galactin-3 (Gal-3), adiponectin (APN), and irisin, have significant changes in the clinical course of the various stages of DCM, suggesting that we may have a positive effect on the identification of DCM. As a summary of the current state of knowledge regarding DCM biomarkers, this review aims to inspire new ideas for identifying clinical markers and related pathophysiologic mechanisms that could be used in the early diagnosis and treatment of DCM.

Benzophenones alter autophagy and ER stress gene expression in pancreatic beta cells in vitro

Benzophenones (BPs) are endocrine disruptors frequently used in sunscreens and food packaging as UV blockers. Our goal was to assess the effect of benzophenone 2 (BP2) and 3 (BP3) on gene expression related to autophagy process and ER stress response in pancreatic beta cells. To that end, the mouse pancreatic beta cell line MIN6B1 was treated with 10 µM BP2 or BP3 in the presence or absence of the autophagy-inhibitor chloroquine (CQ, 10 µM) or the autophagy-inducer rapamycin (RAPA, 50 nM) during 24 h. BP3 inhibited the expression of the autophagic gene Ulk1, and additional effects were uncovered when autophagy was modified by CQ and RAPA. BP3 counteracted CQ-induced Lamp2 expression but did not compensate CQ-induced Sqstm1/p62 gene transcription, neither BP2. Nevertheless, the BPs did not alter the autophagic flux. In relation to ER stress, BP3 inhibited unspliced and spliced Xbp1 mRNA levels in the presence or absence of CQ, totally counteracted CQ-induced Chop gene expression, and partially reverted CQ-induced Grp78/Bip mRNA levels, while BP2 also partially inhibited Grp78/Bip mRNA induction by CQ. In conclusion, BPs, principally BP3, affect cellular adaptive responses related to autophagy, lysosomal biogenesis, and ER stress in pancreatic beta cells, indicating that BP exposure could lead to beta cell dysfunction.

Probing the Superiority of Diselenium Bond on Docetaxel Dimeric Prodrug Nanoassemblies: Small Roles Taking Big Responsibilities

The current state of chemotherapy is far from satisfaction, restricted by the inefficient drug delivery and the off-target toxicity. Prodrug nanoassemblies are emerging as efficient platforms for chemotherapy. Herein, three docetaxel dimeric prodrugs are designed using diselenide bond, disulfide bond, or dicarbide bond as linkages. Interestingly, diselenide bond-bridged dimeric prodrug can self-assemble into stable nanoparticles with impressive high drug loading (≈70%, w/w). Compared with disulfide bond and dicarbide bond, diselenide bond greatly facilitates the self-assembly of dimeric prodrug, and then improves the colloidal stability, blood circulation time, and antitumor efficacy of prodrug nanoassemblies. Furthermore, the redox-sensitive diselenide bond can specifically respond to the overexpressed reactive oxygen species and glutathione in tumor cells, leading to tumor-specific drug release. Therefore, diselenide bond bridged prodrug nanoassemblies exhibit discriminating cytotoxicity between tumor cells and normal cells, significantly alleviating the systemic toxicity of docetaxel. The present work gains in-depth insight into the impact of diselenide bond on the dimeric prodrug nanoassemblies, and provides promising strategies for the rational design of the high efficiency-low toxicity chemotherapeutical nanomedicines.

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.

Preventive Effect of Cardiotrophin-1 Administration before DSS-Induced Ulcerative Colitis in Mice

Ulcerative colitis is a relatively frequent, chronic disease that impacts significantly the patient's quality of life. Although many therapeutic options are available, additional approaches are needed because many patients either do not respond to current therapies or show significant side effects. Cardiotrophin-1 (CT-1) is a cytokine with potent cytoprotective, anti-inflammatory, and antiapoptotic properties. The purpose of this study was to assess if the administration of CT-1 could reduce colon damage in mice with experimental colitis was induced with 5% dextran sulfate sodium (DSS) in the drinking water. Half of the mice received an i.v. dose of CT-1 (200 µg/kg) 2 h before and 2 and 4 days after DSS administration. Animals were followed during 7 days after DSS administration. The severity of colitis was measured by standard scores. Colon damage was assessed by histology and immunohistochemistry. Inflammatory mediators were measured by Western blot and PCR. CT-1 administration to DSS-treated mice ameliorated both the clinical course (disease activity index), histological damage, inflammation (colon expression of TNF-α, IL-17, IL-10, INF IFN-γ, and iNOS), and apoptosis. Our results suggest that CT-1 administration before induction of colitis improves the clinical course, tissue damage, and inflammation in DSS-induced colitis in mice.

Cytoprotective effects of olesoxime on isolated human pancreatic islets in order to attenuate apoptotic pathway

BACKGROUND AND PURPOSE

Islet transplantation is considered as a promising approach in the treatment of diabetes type 1. In this regard, optimal culture of the pancreatic islets is promising in the success of transplantation. In the present study, the effect of olesoxime, as an antiapoptotic substance, was evaluated on human islet culture.

EXPERIMENTAL APPROACH

The pancreatic islets were isolated by mechanical and enzymatic techniques. After overnight recovery, the islets were treated by different concentrations of olesoxime for 24 and 72 h. Then, they were examined in terms of viability, apoptosis, genes and proteins expression including BAX, BCL2, active caspase-3, and insulin. Moreover, the islets function was evaluated through the glucose-induced insulin and C-peptide secretion assay.

KEY RESULTS

Our findings showed that the islets increased in apoptosis and the decreased in viability after 72 h; also, insulin and C-peptide secretion reduced. However, in the presence of olesoxime, BAX/BCL2 ratio and the activation of caspase-3 were decreased. Therefore, olesoxime could improve the viability of the islets with the decrease of apoptosis.

CONCLUSION

The application of olesoxime can reduce the stressful condition for the islets in vitro and subsequently improve their viability and functionality.

Cardiotrophin-1 attenuates experimental colitis in mice

Cardiotrophin-1 (CT-1) holds potent anti-inflammatory, cytoprotective, and anti-apoptotic effects in the liver, kidneys, and heart. In the present study, the role of endogenous CT-1 and the effect of exogenous CT-1 were evaluated in experimental ulcerative colitis. Colitis was induced in CT-1 knockout and wild-type (WT) mice by administration of dextran sulphate sodium (DSS) in the drinking water during 7 days. CT-1 knockout mice showed higher colon damage and disease severity than WT mice. In addition, CT-1 (200 µg/kg/day, iv) or vehicle (as control) was administered during 3 days to WT, colitic mice, starting on day 4 after initiation of DSS. Disease activity index (DAI), inflammatory markers (tumor necrosis factor α (TNF-α), INFγ, IL-17, IL-10, inducible nitric oxide synthase (iNOS)), colon damage, apoptosis (cleaved caspase 3), nuclear factor κB (NFκB) and STAT-3 activation, and bacterial translocation were measured. Compared with mice treated with DSS, mice also treated with exogenous CT-1 showed lower colon damage, DAI, plasma levels of TNFα, colon expression of TNF-α, INFγ, IL-17, iNOS and cleaved caspase 3, higher NFκB and signal transducer and activator of transcription 3 (STAT3) pathways activation, and absence of bacterial translocation. We conclude that endogenous CT-1 plays a role in the defense and repair response of the colon against ulcerative lesions through an anti-inflammatory and anti-apoptotic effect. Supplementation with exogenous CT-1 ameliorates disease symptoms, which opens a potentially new therapeutic strategy for ulcerative colitis.

Serum and gene expression levels of CT-1, IL-6, and TNF-α after a lifestyle intervention in obese children

BACKGROUND

Inflammation related molecules such as tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), and cardiotrophin-1 (CT-1) are highly expressed in obese individuals and could partly explain some comorbidities associated to obesity. In obese children, lifestyle interventions are able to lower inflammation and reduce cardiovascular risk factors associated with obesity. The aim of the present work was to study changes in inflammation-related molecules serum and peripheral blood mononuclear cells (PBMC) transcript levels after a 10-week lifestyle intervention in obese children and asses their potential association with glucose metabolism.

METHODS

Twenty-three obese children (mean age 11.5 years; 48% males) underwent a 10-week lifestyle not controlled intervention trial. Anthropometric and biochemical measurements were analyzed. Transcript analysis for CT-1, IL-6, and TNF-α in PBMC were performed by RT-PCR. Serum cytokine levels were also measured at baseline and after 10-weeks.

RESULTS

Participants achieved a significant reduction in body adiposity (0.34 decrease in body mass index-standard deviation), total cholesterol, and glucose levels after 10-weeks. A Significant decrease in serum TNF-α and C reactive protein (CRP) were observed. CT-1 transcript levels were significantly reduced (P = .005) after lifestyle intervention, and these changes were significantly correlated with changes in serum CT-1 levels (r = 0.451; P = .031). In multiple regression analysis baseline CT-1 transcript levels were positively associated with final insulin (R² = 0.506; P = .035) and HOMA-IR values (R² = 0.473; P = .034).

CONCLUSIONS

We reported that serum CRP, TNF-α, as well as PBMC CT-1 transcript levels were reduced after lifestyle intervention in obese children. More studies are needed to clarify the role of inflammation-related molecules in glucose metabolism.

Magnesium valproate ameliorates type 1 diabetes and cardiomyopathy in diabetic rats through estrogen receptors

Estrogen is known to exhibit cardioprotective and antihyperlipidemic action. Valproic acid has been shown to upregulate estrogen receptors (ERs) in breast and prostate cancer tissues. No pharmacological evaluations for magnesium valproate (MgV) so far have been done for diabetic cadio-lipidemic complications. Based on the above context, current study was undertaken to evaluate the therapeutic effectiveness of MgV in cardiac complications associated with type-1 diabetes mellitus in rats wherein diabetes was induced by single tail vein injection of streptozotocin (STZ, 45mg/kg, IV) in female Sprague Dawley rats and treatment of MgV (210mg/kg, PO) was given for eight weeks to diabetic animals, after which, various biochemical and cardiac biomarkers, hypertrophic, hemodynamic and histological parameters along with immunohistochemistry of ERs in the left ventricle (LV) were estimated. MgV treatment significantly controlled hyperglycemia and dyslipidemia, reduced elevated cardiac biomarkers and C-reactive protein(CRP), significantly improved hemodynamic functions and increased the rate of pressure development and decay. MgV also significantly reduced left ventricular hypertrophy index and cardiac hypertrophy index, LV wall thickness, LV collagen, cardiomyocyte diameter and prevented the oxidative stress with significant increase in Na⁺-K⁺-ATPase activity in LV. Moreover, MgV reversed STZ-induced histological alterations and decreased glycogen content in LV and increased the ER_β expressions in LV as evidenced by immunohistochemistry. The result indicated that MgV prevented disease progression in the early stage of diabetic cardiomyopathy which seems to be mediated by upregulation of estrogen receptors in LV tissue.

STAT3 modulates β-cell cycling in injured mouse pancreas and protects against DNA damage

Partial pancreatic duct ligation (PDL) of mouse pancreas induces a doubling of the β-cell mass mainly through proliferation of pre-existing and newly formed β-cells. The molecular mechanism governing this process is still largely unknown. Given the inflammatory nature of PDL and inflammation-induced signaling via the signal transducer and activator of transcription 3 (STAT3), the activation and the role of STAT3 in PDL-induced β-cell proliferation were investigated. Duct ligation stimulates the expression of several cytokines that can act as ligands inducing STAT3 signaling and phosphorylation in β-cells. β-Cell cycling increased by conditional β-cell-specific Stat3 knockout and decreased by STAT3 activation through administration of interleukin-6. In addition, the level of DNA damage in β-cells of PDL pancreas increased after deletion of Stat3. These data indicate a role for STAT3 in maintaining a steady state in the β-cell, by modulating its cell cycle and protection from DNA damage.

Hexarelin Protects Rodent Pancreatic Β-Cells Function from Cytotoxic Effects of Streptozotocin Involving Mitochondrial Signalling Pathways In Vivo and In Vitro

Mitochondrial functions are crucial for pancreatic β-cell survival and glucose-induced insulin secretion. Hexarelin (Hex) is a synthetic small peptide ghrelin analogue, which has been shown to protect cardiomyocytes from the ischemia-reperfusion process. In this study, we used in vitro and in vivo models of streptozotocin (STZ)-induced β-cell damage to study the protective effect of Hex and the associated mechanisms. We found that STZ produced a cytotoxic effect in a dose- and time-dependent manner in MIN6 cells (a mouse β-cell line). Hex (1.0 μM) decreased the STZ-induced damage in β-cells. Rhodamine 123 assay and superoxide DHE production assay revealed that Hex ameliorated STZ-induced mitochondrial damage and excessive superoxide activity in β-cells. In addition, Hex significantly reduced STZ-induced expression of cleaved Caspases-3, Caspases-9 and the ratio of pro-apoptotic protein Bax to anti-apoptotic protein Bcl-2 in MIN6 cells. We further examined the in vivo effect of Hex in a rat model of type 1 diabetes induced by STZ injection. Hex ameliorated STZ-induced decrease in plasma insulin and protected the structure of islets from STZ-induced disruption. Hex also ameliorated STZ-induced expression of cleaved Caspase-9 and the Bax in β-cells. In conclusion, our data indicate that Hex is able to protects β-cell mass from STZ-caused cytotoxic effects involving mitochondrial pathways in vitro and in vivo. Hex may serve as a potential protective agent for the management of diabetes.

Prediction of type 1 diabetes in Sardinian schoolchildren using islet cell autoantibodies: 10-year follow-up of the Sardinian schoolchildren type 1 diabetes prediction study

AIMS

Stable genetic background makes individuals from the Mediterranean island of Sardinia ideal to define the predictive power of islet-related autoantibodies (IRAs): glutamic acid decarboxylase antibodies (GADA), tyrosine phosphatase-like antibodies (IA-2A), islet cell antibodies (ICA) to identify T1DM progressors. The aims of the present study were: (1) determination of IRAs reference limits in healthy non-diabetic Sardinian schoolchildren (SSc). (2) Predictive power evaluation of IRAs as single or combined determination to identify islet to identify T1DM progressors.

METHODS

Between 1986 and 1994, 8448 SSc were tested for IRAs. All were followed up for 10 years. The predictive power of single or combination of IRAs was determined as hazard ratio (HR), sensitivity, specificity, area under the ROC curve, negative and positive predictive value (NPV, PPV).

RESULTS

All 43 progressors to T1DM, but three showed at least one autoantibody positivity. HR for any single-autoantibody positivity was 55.3 times greater when compared to SSc negative for all IRAs. Any single autoantibody performed at least 64.9 % sensitivity with PPV always lower than 16 %. The best performing combination was ICA, plus IA-2A (showing 52.6 % sensitivity, 99.8 % specificity, 0.76 area under the ROC curve, 51.3 % PPV and 99.8 % NPV.

CONCLUSIONS

Determination of IRAs reference limits in healthy SSc by standard statistical methods is crucial to establish the power of IRAs as progression markers to T1DM. Our data offer a solid rationale for future testing of ICA and IA-2A as routine laboratory markers to identify individuals at high risk of T1DM in the general population.

Cardiotrophin-1: A multifaceted cytokine

Cardiotrophin-1 (CT-1) is a member of the gp130 family of cytokines that have pleiotropic functions on different tissues and cell types. Although many effects of CT-1 have been described on the heart, there is an extensive research showing important protective effects in other organs such as liver, kidney or nervous system. Recently, several studies have pointed out that CT-1 might also play a key role in the regulation of body weight and intermediate metabolism. This paper will review many aspects of CT-1 physiological role in several organs and discuss data for consideration in therapeutic approaches.

Common genetic variation in the human CTF1 locus, encoding cardiotrophin-1, determines insulin sensitivity

Aims/Hypothesis

Recently, cardiotrophin-1, a member of the interleukin-6 family of cytokines was described to protect beta-cells from apoptosis, to improve glucose-stimulated insulin secretion and insulin resistance, and to prevent streptozotocin-induced diabetes in mice. Here, we studied whether common single nucleotide polymorphisms (SNPs) in the CTF1 locus, encoding cardiotrophin-1, influence insulin secretion and insulin sensitivity in humans.

Methods

We genotyped 1,771 German subjects for three CTF1 tagging SNPs (rs1046276, rs1458201, and rs8046707). The subjects were metabolically characterized by an oral glucose tolerance test. Subgroups underwent magnetic resonance (MR) imaging/spectroscopy and hyperinsulinaemic-euglycaemic clamps.

Results

After appropriate adjustment, the minor allele of CTF1 SNP rs8046707 was significantly associated with decreased in vivo measures of insulin sensitivity. The other tested SNPs were not associated with OGTT-derived sensitivity parameters, nor did the three tested SNPs show any association with OGTT-derived parameters of insulin release. In the MR subgroup, SNP rs8046707 was nominally associated with lower visceral adipose tissue. Furthermore, the SNP rs1458201 showed a nominal association with increased VLDL levels.

Conclusions

In conclusion, this study, even though preliminary and awaiting further confirmation by independent replication, provides first evidence that common genetic variation in CTF1 could contribute to insulin sensitivity in humans. Our SNP data indicate an insulin-desensitizing effect of cardiotrophin-1 and underline that cardiotrophin-1 represents an interesting target to influence insulin sensitivity.

Activation of angiotensin type 2 receptors partially ameliorates streptozotocin-induced diabetes in male rats by islet protection

We have previously demonstrated that rat islets express a high density of angiotensin type 2 receptors and that activation of this receptor evokes insulinotropic effect. In this study, we evaluated the protective effects of Compound 21 (C21), a nonpeptide angiotensin type 2 receptor agonist, on islets in streptozotocin (STZ)-induced diabetes. Rats were assigned to five groups: normal, STZ, and STZ plus C21 (0.24, 0.48, and 0.96 mg/kg·d). C21 was continually infused by a sc implanted osmotic minipump for 14 days, and STZ was bolus injected on day 7. Body weight, water intake, urine excretion, and blood glucose were monitored daily. On the last day, the rats received an oral glucose tolerance test, and the pancreata were saved to examine islet morphology and biochemical parameters of oxidative stress and apoptosis. We found that, compared with control STZ rats, C21-treated STZ rats displayed less water intake and urine excretion, lower blood glucose, higher serum insulin concentration, and improved glucose tolerance. These rats had more islets, larger islet mass, and up-regulated insulin protein and proinsulin 2 mRNA expressions in the pancreas. Their islets displayed lower superoxide, decreased gp91 expression, and increased superoxide dismutase 1 expression as well as less apoptosis and down-regulated caspase-3 expression. In the epididymal adipose tissue of these rats, we found a decreased adipocyte size and up-regulated adipocyte protein 2 expression. The protective effects of C21 on β-cells against the toxic effects of STZ were also confirmed in cultured INS-1E cells. These data suggest that C21 ameliorates STZ-induced diabetes by protecting pancreatic islets via antioxidative and antiapoptotic effects.