Alejandra Guillermina Miranda-Díaz

Oxidative Stress in Diabetic Nephropathy with Early Chronic Kidney Disease

The increase in the prevalence of diabetes mellitus (DM) and the secondary kidney damage produces diabetic nephropathy (DN). Early nephropathy is defined as the presence of microalbuminuria (30–300 mg/day), including normal glomerular filtration rate (GFR) or a mildly decreased GFR (60–89 mL/min/1.73 m2), with or without overt nephropathy. The earliest change caused by DN is hyperfiltration with proteinuria. The acceptable excretion rate of albumin in urine is <30 mg/day. Albuminuria represents the excretion of >300 mg/day. Chronic kidney disease (CKD) is characterized by abnormalities in renal function that persist for >3 months with health implications. Alterations in the redox state in DN are caused by the persistent state of hyperglycemia and the increase in advanced glycation end products (AGEs) with ability to affect the renin-angiotensin system and the transforming growth factor-beta (TGF-β), producing chronic inflammation and glomerular and tubular hypertrophy and favoring the appearance of oxidative stress. In DN imbalance between prooxidant/antioxidant processes exists with an increase in reactive oxygen species (ROS). The overproduction of ROS diminishes expression of the antioxidant enzymes (manganese superoxide dismutase, glutathione peroxidase, and catalase). The early detection of CKD secondary to DN and the timely identification of patients would permit decreasing its impact on health.

Diabetic Polyneuropathy in Type 2 Diabetes Mellitus: Inflammation, Oxidative Stress, and Mitochondrial Function

Diabetic polyneuropathy (DPN) is defined as peripheral nerve dysfunction. There are three main alterations involved in the pathologic changes of DPN: inflammation, oxidative stress, and mitochondrial dysfunction. Inflammation induces activation of nuclear factor kappa B, activator protein 1, and mitogen-activated protein kinases. Oxidative stress induced by hyperglycemia is mediated by several identified pathways: polyol, hexosamine, protein kinase C, advanced glycosylation end-products, and glycolysis. In addition, mitochondrial dysfunction accounts for most of the production of reactive oxygen and nitrosative species. These free radicals cause lipid peroxidation, protein modification, and nucleic acid damage, to finally induce axonal degeneration and segmental demyelination. The prevalence of DPN ranges from 2.4% to 78.8% worldwide, depending on the diagnostic method and the population assessed (hospital-based or outpatients). Risk factors include age, male gender, duration of diabetes, uncontrolled glycaemia, height, overweight and obesity, and insulin treatment. Several diagnostic methods have been developed, and composite scores combined with nerve conduction studies are the most reliable to identify early DPN. Treatment should be directed to improve etiologic factors besides reducing symptoms; several approaches have been evaluated to reduce neuropathic impairments and improve nerve conduction, such as oral antidiabetics, statins, and antioxidants (alpha-lipoic acid, ubiquinone, and flavonoids).

The effect of ubiquinone in diabetic polyneuropathy: A randomized double-blind placebo-controlled study

INTRODUCTION Diabetic polyneuropathy aetiology is based on oxidative stress generation due to production of reactive oxygen species. Ubiquinone is reduced to ubiquinol and redistributed into lipoproteins, possibly to protect them from oxidation. AIMS To evaluate the impact of oral ubiquinone in diabetic polyneuropathy, and the role of lipid peroxidation (LPO) and nerve growth factor (NGF-β). METHODS We conducted a double-blind, placebo-controlled clinical trial, patients were randomized to ubiquinone (400 mg) or placebo daily for 12 weeks. Main outcomes were clinical scores, nerve conduction studies, LPO, NGF-β and safety. RESULTS Twenty four patients on experimental group and twenty five on control group met the inclusion criteria (mean age 56 years, 22% male and 78% female, mean evolution of type 2 diabetes mellitus 10.7 years). Significant improvement on experimental vs control group was found in neuropathy symptoms score (from 2.5 ± 0.7 to 1 ± 0.8, p<0.001), neuropathy impairment score (5.5 ± 4 to 3.1 ± 2.6, p<0.001), sural sensory nerve amplitude (13.0 ± 6.1 to 15.8 ± 5.1 μV, p=0.049), peroneal motor nerve conduction velocity (39.7 ± 5.0 to 47.8 ± 4.9 m/s, p=0.047), and ulnar motor nerve conduction velocity (48.8 ± 6.8 to 54.5 ± 6.1m/s, p=0.046). There was a significant reduction of LPO in subjects treated with ubiquinone vs placebo (16.7 ± 8.6 and 23.2 ± 15.8 nmol/mL, respectively) with p<0.05, and NGF-β did not change (control 66.5 ± 26.7 vs. experimental 66.8 ± 28.4 pg/mL, p=0.856). No drug-related adverse reactions were reported. CONCLUSIONS Twelve weeks treatment with ubiquinone improves clinical outcomes and nerve conduction parameters of diabetic polyneuropathy; furthermore, it reduces oxidative stress without significant adverse events.

Effect of rosuvastatin on diabetic polyneuropathy: a randomized, double-blind, placebo-controlled Phase IIa study.

Background Diabetic neuropathy affects 50%–66% of patients with diabetes mellitus. Oxidative stress generates nerve dysfunction by causing segmental demyelinization and axonal degeneration. Antioxidants are considered to be the only etiologic management for diabetic polyneuropathy, and statins such as rosuvastatin increase nitric oxide bioavailability and reduce lipid peroxidation. The aim of this study was to evaluate the antioxidant effect of rosuvastatin in diabetic polyneuropathy. Methods We conducted a randomized, double-blind, placebo-controlled Phase IIa clinical trial in patients with type 2 diabetes and diabetic polyneuropathy (DPN) stage ≥1b. We allocated subjects to two parallel groups (1:1) that received rosuvastatin 20 mg or placebo for 12 weeks. Primary outcomes were neuropathic symptom score, disability score, and nerve conduction studies, and secondary outcomes were glycemic control, lipid and hepatic profile, lipid peroxidation, and nerve growth factor beta (NGF-β) levels. Results Both groups were of similar age and duration since diagnosis of diabetes and DPN. We observed improvement of DPN in the rosuvastatin group from stage 2a (88.2%) to stage 1b (41.2%), improvement of neuropathic symptom score from 4.5±2 to 2.4±1.8, and significant (P=0.001) reductions of peroneal nerve conduction velocity (from 40.8±2.2 to 42.1±1.6 seconds) and lipid peroxidation (from 25.4±2 to 12.2±4.0 nmol/mL), with no significant change in glycemic control or β-NGF. Conclusion The severity, symptoms, and nerve conduction parameters of DPN improved after 12 weeks of treatment with rosuvastatin. These beneficial effects appear to be attributable to reductions in lipid peroxidation and oxidative stress.

YKL-40 expression in CD14+ liver cells in acute and chronic injury

AIM To demonstrate that CD14⁺ cells are an important source of the growth factor YKL-40 in acute and chronic liver damage. METHODS Rats were inoculated with one dose of CCl(4) to induce acute damage. Liver biopsies were obtained at 0, 6, 12, 24, 48 and 72 h. For chronic damage, CCl(4) was administered three days per week for 6 or 8 wk. Tissue samples were collected, and cellular populations were isolated by liver digestion and purified by cell sorting. YKL-40 mRNA and protein expression were evaluated by real-time polymerase chain reaction and western blot. RESULTS Acute liver damage induced a rapid increase of YKL-40 mRNA beginning at 12 h. Expression peaked at 24 h, with a 26-fold increase over basal levels. By 72 h however, YKL-40 expression levels had nearly returned to control levels. On the other hand, chronic damage induced a sustained increase in YKL-40 expression, with 7- and 9-fold higher levels at 6 and 8 wk, respectively. The pattern of YKL-40 expression in different subpopulations showed that CD14⁺ cells, which include Kupffer cells, are a source of YKL-40 after acute damage at 72 h [0.09 relative expression units (REU)] as well as after chronic injury at 6 wk (0.11 REU). Hepatocytes, in turn, accounted for 0.06 and 0.01 REU after 72 h (acute) or 6 wk (chronic), respectively. The rest of the CD14⁻ cells (including T lymphocytes, B lymphocytes, natural killer and natural killer T cells) yielded 0.07 and 0.15 REU at 72 h and 6 wk, respectively. YKL-40 protein expression in liver was detected at 72 h as well as 6 and 8 wk, with the highest expression relative to controls (11-fold; P ≤ 0.05) seen at 6 wk. Macrophages were stimulated by lipopolysaccharide. We demonstrate that under these conditions, these cells showed maximum expression of YKL-40 at 12 h, with P < 0.05 compared with controls. CONCLUSION Hepatic CD14⁺ cells are an YKL-40 mRNA and protein source in acute and chronic liver injury, with expression patterns similar to growth factors implicated in inflammation-fibrogenesis.

Liver fibrosis secondary to bile duct injury: correlation of Smad7 with TGF-β and extracellular matrix proteins

BackgroundLiver fibrosis is the result of continuous liver injury stemming from different etiological factors. Bile duct injury induces an altered expression of TGF-β, which has an important role in liver fibrosis because this cytokine induces the expression of target genes such as collagens, PAI-1, TIMPs, and others that lead to extracellular matrix deposition. Smad7 is the principal inhibitor that regulates the target gene transcription of the TGF-β signaling. The aim of the study was to determine whether Smad7 mRNA expression correlates with the gene expression of TGF-β, Col I, Col III, Col IV, or PAI-1 in liver fibrosis secondary to bile duct injury (BDI).ResultsSerum TGF-β concentration was higher in BDI patients (39 296 pg/ml) than in liver donors (9008 pg/ml). Morphometric analysis of liver sections showed 41.85% of tissue contained fibrotic deposits in BDI patients. mRNA expression of Smad7, Col I, and PAI-1 was also significantly higher (P < 0.05) in patients with BDI than in controls. Smad7 mRNA expression correlated significantly with TGF-β concentration, Col I and Col III expression, and the amount of fibrosis.ConclusionWe found augmented serum concentration of TGF-β and an increase in the percentage of fibrotic tissue in the liver of BDI patients. Contrary to expected results, the 6-fold increase in Smad7 expression did not inhibit the expression of TGF-β, collagens, and PAI-1. We also observed greater expression of Col I and Col III mRNA in BDI patients and significant correlations between their expression and TGF-β concentration and Smad7 mRNA expression.

Effects of Ezetimibe/Simvastatin and Rosuvastatin on Oxidative Stress in Diabetic Neuropathy: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Objective. To evaluate the effects of ezetimibe/simvastatin (EZE/SIMV) and rosuvastatin (ROSUV) on oxidative stress (OS) markers in patients with diabetic polyneuropathy (DPN). Methods. We performed a randomized, double-blind, placebo-controlled phase III clinical trial in adult patients with Type 2 Diabetes Mellitus (T2DM) and DPN, as evaluated by composite scores and nerve conduction studies (NCS). Seventy-four subjects with T2DM were allocated 1 : 1 : 1 to placebo, EZE/SIMV 10/20 mg, or ROSUV 20 mg for 16 weeks. All patients were assessed before and after treatment: primary outcomes were lipid peroxidation (LPO), and nitric oxide (NO) surrogate levels in plasma; secondary outcomes included NCS, neuropathic symptom scores, and metabolic parameters. Data were expressed as mean ± SD or SEM, frequencies, and percentages; we used nonparametric analysis. Results. LPO levels were reduced in both statin arms after 16 weeks of treatment (p < 0.05 versus baseline), without changes in the placebo group. NO levels were not significantly affected by statin treatment, although a trend towards significance concerning increased NO levels was noted in both statin arms. No significant changes were observed for the NCS or composite scores. Discussion. EZE/SIMV and ROSUV are superior to placebo in reducing LPO in subjects with T2DM suffering from polyneuropathy. This trial is registered with NCT02129231.

Oxidants, antioxidants and mitochondrial function in non-proliferative diabetic retinopathy.

Diabetic retinopathy (DR) is a preventable cause of visual disability. The aims of the present study were to investigate levels and behavior oxidative stress markers and mitochondrial function in non‐proliferative DR (NPDR) and to establish the correlation between the severity of NPDR and markers of oxidative stress and mitochondrial function.

Oxidants, antioxidants and mitochondrial function in non‐proliferative diabetic retinopathy (在非增殖性糖尿病视网膜病变中的氧化剂、抗氧化剂以及线粒体功能)

Diabetic retinopathy (DR) is a preventable cause of visual disability. The aims of the present study were to investigate levels and behavior oxidative stress markers and mitochondrial function in non‐proliferative DR (NPDR) and to establish the correlation between the severity of NPDR and markers of oxidative stress and mitochondrial function.

The Role of Oxidative Stress, Mitochondrial Function, and Autophagy in Diabetic Polyneuropathy

Diabetic polyneuropathy (DPN) is the most frequent and prevalent chronic complication of diabetes mellitus (DM). The state of persistent hyperglycemia leads to an increase in the production of cytosolic and mitochondrial reactive oxygen species (ROS) and favors deregulation of the antioxidant defenses that are capable of activating diverse metabolic pathways which trigger the presence of nitro-oxidative stress (NOS) and endoplasmic reticulum stress. Hyperglycemia provokes the appearance of micro- and macrovascular complications and favors oxidative damage to the macromolecules (lipids, carbohydrates, and proteins) with an increase in products that damage the DNA. Hyperglycemia produces mitochondrial dysfunction with deregulation between mitochondrial fission/fusion and regulatory factors. Mitochondrial fission appears early in diabetic neuropathy with the ability to facilitate mitochondrial fragmentation. Autophagy is a catabolic process induced by oxidative stress that involves the formation of vesicles by the lysosomes. Autophagy protects cells from diverse stress factors and routine deterioration. Clarification of the mechanisms involved in the appearance of complications in DM will facilitate the selection of specific therapeutic options based on the mechanisms involved in the metabolic pathways affected. Nowadays, the antioxidant agents consumed exogenously form an adjuvant therapeutic alternative in chronic degenerative metabolic diseases, such as DM.