Advanced glycation end products and antioxidant status in nondiabetic and streptozotocin induced diabetic rats: effects of copper treatment

Diabetes mellitus exacerbates experimental autoimmune myasthenia gravis via modulating both adaptive and innate immunity

BACKGROUND

Diabetes mellitus (DM) is a common concomitant disease of late-onset myasthenia gravis (MG). However, the impacts of DM on the progression of late-onset MG were unclear.

METHODS

In this study, we examined the immune response in experimental autoimmune myasthenia gravis (EAMG) rats with DM or not. The phenotype and function of the spleen and lymph nodes were determined by flow cytometry. The serum antibodies, Tfh cells, and germinal center B cells were determined by ELISA and flow cytometry. The roles of advanced glycation end products (AGEs) in regulating Tfh cells were further explored in vitro by co-culture assays.

RESULTS

Our results indicated clinical scores of EAMG rats were worse in diabetes rats compared to control, which was due to the increased production of anti-R97-116 antibody and antibody-secreting cells. Furthermore, diabetes induced a significant upregulation of Tfh cells and the subtypes of Tfh1 and Tfh17 cells to provide assistance for antibody production. The total percentages of B cells were increased with an activated statue of improved expression of costimulatory molecules CD80 and CD86. We found CD4⁺ T-cell differentiation was shifted from Treg cells towards Th1/Th17 in the DM+EAMG group compared to the EAMG group. In addition, in innate immunity, diabetic EAMG rats displayed more CXCR5 expression on NK cells. However, the expression of CXCR5 on NKT cells was down-regulated with the increased percentages of NKT cells in the DM+EAMG group. Ex vivo studies further indicated that Tfh cells were upregulated by AGEs instead of hyperglycemia. The upregulation was mediated by the existence of B cells, the mechanism of which might be attributed the elevated molecule CD40 on B cells.

CONCLUSIONS

Diabetes promoted both adaptive and innate immunity and exacerbated clinical symptoms in EAMG rats. Considering the effect of diabetes, therapy in reducing blood glucose levels in MG patients might improve clinical efficacy through suppressing the both innate and adaptive immune responses. Additional studies are needed to confirm the effect of glucose or AGEs reduction to seek treatment for MG.

Streptozotocin (STZ)-Induced Diabetes Affects Tissue Trace Element Content in Rats in a Dose-Dependent Manner

The objective of the present study was investigation of tissue trace element distribution in a streptozotocin model of DM1 in rats. DM1 was modeled in 2-month-old male Wistar rats (n = 30) using intraperitoneal injection of 45 mg/kg b.w. (STZ1) and 55 mg/kg b.w. streptozotocin (STZ2), whereas control animals were injected with physiological saline. The rats were subjected to oral glucose tolerance test (OGTT) and HbA1c level assessment at day 14. At day 30, blood serum, liver, kidney, and heart samples were collected for tissue trace element assessment using inductively coupled plasma mass spectrometry (ICP-MS). STZ-treated rats were characterized by lack of significant weight gain and elevated HbA1c and blood glucose levels. ICP-MS analysis demonstrated a dose-dependent accumulation of Cu, Mn, Mo, and Se levels in the liver. Correspondingly, the dose-dependent increase in renal Cu, Mn, V, and Zn levels was significant, whereas the observed trend for kidney V and Mo accumulation was nearly significant. The patterns of trace element content in the myocardium of STZ-exposed rats were quite different from those observed for liver and kidney. Only cardiac Zn content was characterized by a significant decrease. Serum Co, Cr, Cu, Se, V, and Mo levels were characterized by a significant decrease in response to STZ-induced diabetes. Generally, the obtained data demonstrate that diabetes is associated with altered copper, manganese, molybdenum, chromium, and vanadium handling. In turn, only altered Zn status may provide a link to diabetic cardiotoxicity. However, the particular mechanisms of both impaired metal handling in STZ diabetes and their potential anti-diabetic activity require further investigation.

Recent advances in detection of AGEs: Immunochemical, bioanalytical and biochemical approaches

Advanced glycation end products (AGEs) are a cohort of heterogeneous compounds that are formed after the nonenzymatic glycation of proteins, lipids and nucleic acids. Accumulation of AGEs in the body is implicated in various pathophysiological conditions like diabetes, cardiovascular diseases and atherosclerosis. Numerous studies have reported the connecting link between AGEs and the various complications associated with diseases. Hence, detection and measurement of AGEs becomes centrally important to understand and manage the menace created by AGEs inside the body. In recent years, an increasing number of immunotechniques as well as bioanalytical techniques have been developed to efficiently measure the levels of AGEs, but most of them are still far away from being clinically consistent, as relative disparity and ambiguity masks their standardization. This article is designed to critically review the recent advances and the emerging techniques for detection of AGEs. It is an attempt to summarize the major techniques that exist currently for the detection of AGEs both qualitatively and quantitatively. This review primarily focuses on the detection and quantification of AGEs which are formed in vivo. Immunochemical approach though costly but most effective and accurate method to measure the level of AGEs. Literature review suggests that detection of autoantibody targeting AGEs is a promising way that can be utilized for detection of AGEs. Future research efforts should be dedicated to develop this method in order to push forward the clinical applications of detection of AGEs.

Impaired insulin signaling and mechanisms of memory loss

Insulin is secreted from the β-cells of the pancreas and helps maintain glucose homeostasis. Although secreted peripherally, insulin also plays a profound role in cognitive function. Increasing evidence suggests that insulin signaling in the brain is necessary to maintain health of neuronal cells, promote learning and memory, decrease oxidative stress, and ultimately increase neuronal survival. This chapter summarizes the different facets of insulin signaling necessary for learning and memory and additionally explores the association between cognitive impairment and central insulin resistance. The role of impaired insulin signaling in the advancement of cognitive dysfunction is relevant to the current debate of whether the shared pathophysiological mechanisms between diabetes and cognitive impairment implicate a direct relationship. Here, we summarize a vast amount of literature that suggests a strong association between impaired brain insulin signaling and cognitive impairment.

Evaluating oxidative stress in human cardiovascular disease: methodological aspects and considerations

Oxidative stress is a key feature in atherogenesis, since reactive oxygen species (ROS) are involved in all stages of the disease, from endothelial dysfunction to atheromatic plaque formation and rupture. It is therefore important to identify reliable biomarkers allowing us to monitor vascular oxidative stress status. These may lead to improved understanding of disease pathogenesis and development of new therapeutic strategies. Measurement of circulating biomarkers of oxidative stress is challenging, since circulation usually behaves as a separate compartment to the individual structures of the vascular wall. However, measurement of stable products released by the reaction of ROS and vascular/circulating molecular structures is a particularly popular approach. Serum lipid hydroperoxides, plasma malondialdehyde or urine F2-isoprostanes are widely used and have a prognostic value in cardiovascular disease. Quantification of oxidative stress at a tissue level is much more accurate. Various chemiluminescence and high performance liquid chromatography assays have been developed over the last few years, and some of them are extremely accurate and specific. Electron spin resonance spectroscopy and micro-electrode assays able to detect ROS directly are also widely used. In conclusion, measurement of circulating biomarkers of oxidative stress is valuable, and some of them appear to have predictive value in cardiovascular disease. However, these biomarkers do not necessarily reflect intravascular oxidative stress and therefore cannot be used as therapeutic targets or markers to monitor pharmacological treatments in clinical settings. Measurement of vascular oxidative stress status is still the only reliable way to evaluate the involvement of oxidative stress in atherogenesis.

Correlation between microalbuminuria and urinary copper in type two diabetic patients

INTRODUCTION

Diabetes mellitus and its chronic complications may be associated with alterations in the plasma, tissue, and urinary levels of some trace elements like copper.

MATERIALS AND METHODS

This cross-sectional study evaluates the 24 hour urinary copper levels in type 2 diabetic patients with microalbuminuria in comparison with patients without albuminuria.

RESULTS

Forty-two patients with microalbuminuria (case) and 40 patients without microalbuminuria (control) participated in the study. Mean (CI 95%) urinary copper levels were 36.14 (14.54-57.74) and 14.77μcg /L (10.17-19.37) in the case and control groups respectively (P = 0.003). There was no significant effect of diabetes duration or HbA1c on urinary copper.

CONCLUSION

The present study shows diabetic patients with microalbuminuria have increased urinary copper excretion, however does not exclude the potential toxic effects of this high copper excretion on the progression of diabetic nephropathy.