Increased intracellular generation of reactive oxygen species in mononuclear leukocytes from patients with diabetes mellitus type 2

Metabolic regulation of forkhead box P3 alternative splicing isoforms and their impact on health and disease

Forkhead Box P3 (FOXP3) is crucial for the development and suppressive function of human regulatory T cells (Tregs). There are two predominant FOXP3 splicing isoforms in healthy humans, the full-length isoform and the isoform lacking exon 2, with different functions and regulation mechanisms. FOXP3 splicing isoforms show distinct abilities in the cofactor interaction and the nuclear translocation, resulting in different effects on the differentiation, cytokine secretion, suppressive function, linage stability, and environmental adaptation of Tregs. The balance of FOXP3 splicing isoforms is related to autoimmune diseases, inflammatory diseases, and cancers. In response to environmental challenges, FOXP3 transcription and splicing can be finely regulated by T cell antigen receptor stimulation, glycolysis, fatty acid oxidation, and reactive oxygen species, with various signaling pathways involved. Strategies targeting energy metabolism and FOXP3 splicing isoforms in Tregs may provide potential new approaches for the treatment of autoimmune diseases, inflammatory diseases, and cancers. In this review, we summarize recent discoveries about the FOXP3 splicing isoforms and address the metabolic regulation and specific functions of FOXP3 splicing isoforms in Tregs.

DNA damage-dependent mechanisms of ageing and disease in the macro- and microvasculature

A decline in the function of the macro- and micro-vasculature occurs with ageing. DNA damage also accumulates with ageing, and thus DNA damage and repair have important roles in physiological ageing. Considerable evidence also supports a crucial role for DNA damage in the development and progression of macrovascular disease such as atherosclerosis. These findings support the concept that prolonged exposure to risk factors is a major stimulus for DNA damage within the vasculature, in part via the generation of reactive oxygen species. Genomic instability can directly affect vascular cellular function, leading to cell cycle arrest, apoptosis and premature vascular cell senescence. In contrast, the study of age-related impaired function and DNA damage mechanisms in the microvasculature is limited, although ageing is associated with microvessel endothelial dysfunction. This review examines current knowledge on the role of DNA damage and DNA repair systems in macrovascular disease such as atherosclerosis and microvascular disease. We also discuss the cellular responses to DNA damage to identify possible strategies for prevention and treatment.

Immunological mechanisms contributing to the double burden of diabetes and intracellular bacterial infections

Diabetes has been recognized as an important risk factor for a variety of intracellular bacterial infections, but research into the dysregulated immune mechanisms contributing to the impaired host-pathogen interactions is in its infancy. Diabetes is characterized by a chronic state of low-grade inflammation due to activation of pro-inflammatory mediators and increased formation of advanced glycation end products. Increased oxidative stress also exacerbates the chronic inflammatory processes observed in diabetes. The reduced phagocytic and antibacterial activity of neutrophils and macrophages provides an intracellular niche for the pathogen to replicate. Phagocytic and antibacterial dysfunction may be mediated directly through altered glucose metabolism and oxidative stress. Furthermore, impaired activation of natural killer cells contributes to decreased levels of interferon-γ, required for promoting macrophage antibacterial mechanisms. Together with impaired dendritic cell function, this impedes timely activation of adaptive immune responses. Increased intracellular oxidation of antigen-presenting cells in individuals with diabetes alters the cytokine profile generated and the subsequent balance of T-cell immunity. The establishment of acute intracellular bacterial infections in the diabetic host is associated with impaired T-cell-mediated immune responses. Concomitant to the greater intracellular bacterial burden and potential cumulative effect of chronic inflammatory processes, late hyper-inflammatory cytokine responses are often observed in individuals with diabetes, contributing to systemic pathology. The convergence of intracellular bacterial infections and diabetes poses new challenges for immunologists, providing the impetus for multidisciplinary research.

Association between oxidative stress and telomere length in Type 1 and Type 2 diabetic patients

BACKGROUND

Increasing evidence showed that telomere length was shorter in age-related diseases, but the mechanism of this phenomenon is still unclear.

AIM

To determine whether telomere shortening occurs in Type 1 diabetes (T1D) and Type 2 diabetes (T2D), and explore the effect of antioxidant status on the telomere length.

SUBJECTS AND METHODS

T2D patients (no.=62), T1D patients (no.=34), and non-diabetic subjects used as control (CTL) (no.=40) were included in this study. Leukocyte telomere length ratio (T/S ratio) was measured using a quantitative PCR and analyzed. Antioxidant status was estimated by human 8-hydroxy-desoxyguanosine quantization. Other biomarkers, such as fasting plasma glucose, fasting insulin, glycated hemoglobin (HbA1c) and lipid profile were also measured.

RESULTS

Compared with CTL group [T/S ratio (mean ± SD), 2.39 ± 0.55], leukocyte telomere length was significantly shorter in T2D group (1.67 ± 0.50) and T1D group (1.77 ± 0.50). 8-OHdG that indicated oxidative stress was significantly higher in T2D (2.99 ± 0.85 ng/ml) and T1D (2.03 ± 0.92 ng/ml) group than in CTL group (0.90 ± 0.46 ng/ml). T/S ratio was significantly negatively correlated with age, waist circumference, waist-to-hip ratio, diastolic blood pressure, fasting plasma glucose, HbA1c, homeostasis model assessment of insulin resistance and 8- OHdG in the whole population. 8-OHdG was independent risk factor for telomere shortening in both T1D (p=0.018) and T2D group (p=0.022).

CONCLUSIONS

In our study, shorter telomere length and increased oxidative stress were observed in both T1D and T2D. Older people with central obesity, hyperglycemia, insulin resistance and severe antioxidant status tended to have shorter telomere length. In addition, 8- OHdG was an independent predictor for telomere length for both T1D and T2D patients.

Nordihydroguaiaretic acid attenuates the oxidative stress-induced decrease of CD33 expression in human monocytes

Nordihydroguaiaretic acid (NDGA) is a natural lignan with recognized antioxidant and beneficial properties that is isolated from Larrea tridentata. In this study, we evaluated the effect of NDGA on the downregulation of oxidant stress-induced CD33 in human monocytes (MNs). Oxidative stress was induced by iodoacetate (IAA) or hydrogen peroxide (H₂O₂) and was evaluated using reactive oxygen species (ROS) production, and cell viability. NDGA attenuates toxicity, ROS production and the oxidative stress-induced decrease of CD33 expression secondary to IAA or H₂O₂ in human MNs. It was also shown that NDGA (20 μM) attenuates cell death in the THP-1 cell line that is caused by treatment with either IAA or H₂O₂. These results suggest that NDGA has a protective effect on CD33 expression, which is associated with its antioxidant activity in human MNs.

High glucose concentrations induce TNF-α production through the down-regulation of CD33 in primary human monocytes

BACKGROUND

CD33 is a membrane receptor containing a lectin domain and a cytoplasmic immunoreceptor tyrosine-based inhibitory motif (ITIM) that is able to inhibit cytokine production. CD33 is expressed by monocytes, and reduced expression of CD33 correlates with augmented production of inflammatory cytokines, such as IL-1β, TNF-α, and IL-8. However, the role of CD33 in the inflammation associated with hyperglycemia and diabetes is unknown. Therefore, we studied CD33 expression and inflammatory cytokine secretion in freshly isolated monocytes from patients with type 2 diabetes. To evaluate the effects of hyperglycemia, monocytes from healthy donors were cultured with different glucose concentrations (15-50 mmol/l D-glucose), and CD33 expression and inflammatory cytokine production were assessed. The expression of suppressor of cytokine signaling protein-3 (SOCS-3) and the generation of reactive oxygen species (ROS) were also evaluated to address the cellular mechanisms involved in the down-regulation of CD33.

RESULTS

CD33 expression was significantly decreased in monocytes from patients with type 2 diabetes, and higher levels of TNF-α, IL-8 and IL-12p70 were detected in the plasma of patients compared to healthy donors. Under high glucose conditions, CD33 protein and mRNA expression was significantly decreased, whereas spontaneous TNF-α secretion and SOCS-3 mRNA expression were increased in monocytes from healthy donors. Furthermore, the down-regulation of CD33 and increase in TNF-α production were prevented when monocytes were treated with the antioxidant α-tocopherol and cultured under high glucose conditions.

CONCLUSION

Our results suggest that hyperglycemia down-regulates CD33 expression and triggers the spontaneous secretion of TNF-α by peripheral monocytes. This phenomenon involves the generation of ROS and the up-regulation of SOCS-3. These observations support the importance of blood glucose control for maintaining innate immune function and suggest the participation of CD33 in the inflammatory profile associated with type 2 diabetes.

Amelioration of glucolipotoxicity-induced endoplasmic reticulum stress by a "chemical chaperone" in human THP-1 monocytes

Chronic ER stress is emerging as a trigger that imbalances a number of systemic and arterial-wall factors and promote atherosclerosis. Macrophage apoptosis within advanced atherosclerotic lesions is also known to increase the risk of atherothrombotic disease. We hypothesize that glucolipotoxicity might mediate monocyte activation and apoptosis through ER stress. Therefore, the aims of this study are (a) to investigate whether glucolipotoxicity could impose ER stress and apoptosis in THP-1 human monocytes and (b) to investigate whether 4-Phenyl butyric acid (PBA), a chemical chaperone could resist the glucolipotoxicity-induced ER stress and apoptosis. Cells subjected to either glucolipotoxicity or tunicamycin exhibited increased ROS generation, gene and protein (PERK, GRP-78, IRE1α, and CHOP) expression of ER stress markers. In addition, these cells showed increased TRPC-6 channel expression and apoptosis as revealed by DNA damage and increased caspase-3 activity. While glucolipotoxicity/tunicamycin increased oxidative stress, ER stress, mRNA expression of TRPC-6, and programmed the THP-1 monocytes towards apoptosis, all these molecular perturbations were resisted by PBA. Since ER stress is one of the underlying causes of monocyte dysfunction in diabetes and atherosclerosis, our study emphasize that chemical chaperones such as PBA could alleviate ER stress and have potential to become novel therapeutics.

Comparison of oxidant/antioxidant, detoxification systems in various tissue homogenates and mitochondria of rats with diabetes induced by streptozocin

Objective. Oxidative stress is considered to be the main factor in the development of diabetic complications and tissue injury. our objective was to investigate and compare the oxidant/antioxidant conditions and detoxification mechanisms of the liver, lung, kidney, cardiac tissues, and mitochondria of rats with diabetes induced by streptozocin (STZ). Methods. Rats with diabetes induced by streptozocin were anesthetized by administering 90 mg/kg ketamine hydrochloride and 3 mg/kg xylazine hydrochloride. Thoracic cavities were incised open; liver, lung, kidney, and cardiac tissues were removed and stored at −70°C. All samples were homogenized and mitochondrial fractions were separated. Total Antioxidant Status (TAS), Total Oxidant Status (TOS), Oxidative Stress Index (OSI), Paraoxonase (PON), Arylesterase, Catalase (Cat), Malondialdehyde (MDA), and Glutathion-S-transferase were measured in each fraction. Results. MDA and TOS levels were significantly increased in liver tissues, and T OS and OSI were increased in the mitochondrial fractions of diabetic rats. These increases were not statistically significant compared to the control group. No significant differences were determined in the antioxidant and GST activities. Conclusion. According to our results, oxidative stress has not developed in rats with diabetes induced by streptozocin. The detoxification system was induced; however, this induction did not differ significantly from the controls.

High glucose-induced oxidative stress increases transient receptor potential channel expression in human monocytes

OBJECTIVE

Transient receptor potential (TRP) channel-induced cation influx activates human monocytes, which play an important role in the pathogenesis of atherosclerosis. In the present study, we investigated the effects of high glucose-induced oxidative stress on TRP channel expression in human monocytes.

RESEARCH DESIGN AND METHODS

Human monocytes were exposed to control conditions (5.6 mmol/l d-glucose), high glucose (30 mmol/l d-glucose or l-glucose), 100 micromol/l peroxynitrite, or high glucose in the presence of the superoxide dismutase mimetic tempol (100 micromol/l). TRP mRNA and TRP protein expression was measured using quantitative real-time RT-PCR and quantitative in-cell Western assay, respectively. Calcium influx and intracellular reactive oxygen species were measured using fluorescent dyes.

RESULTS

Administration of high d-glucose significantly increased reactive oxygen species. High d-glucose or peroxynitrite significantly increased the expression of TRP canonical type 1 (TRPC1), TRPC3, TRPC5, TRPC6, TRP melastatin type 6 (TRPM6), and TRPM7 mRNA and TRPC3 and TRPC6 proteins. High d-glucose plus tempol or high l-glucose did not affect TRP expression. Increased oxidative stress by lipopolysaccharide or tumor necrosis factor-alpha increased TRP mRNA expression, whereas the reduction of superoxide radicals using diphenylene iodonium significantly reduced TRP mRNA expression. Increased TRPC3 and TRPC6 protein expression was accompanied by increased 1-oleoyl-2-acetyl-sn-glycerol-induced calcium influx, which was blocked by the TRPC inhibitor 2-aminoethoxydiphenylborane. TRPC6 mRNA was significantly higher in monocytes from 18 patients with type 2 diabetes compared with 28 control subjects (P < 0.05).

CONCLUSIONS

High d-glucose-induced oxidative stress increases TRP expression and calcium influx in human monocytes, pointing to a novel pathway for increased activation of monocytes and hence atherosclerosis in patients with diabetes.

Association of telomere length with type 2 diabetes, oxidative stress and UCP2 gene variation

OBJECTIVE

High oxidative stress potentially leads to accelerated telomere shortening and consequent premature cell senescence, implicated in type 2 diabetes (T2D) development. Therefore, we studied the association of leukocyte telomere length (LTL) with the presence of T2D, as well as the effect on the patients' LTL of plasma oxidative stress and of variation in UCP2, a gene involved in the mitochondrial production of reactive oxygen species.

METHODS

Mean LTL was determined in 569 Caucasian, 103 South Asian and 70 Afro-Caribbean T2D patients aged from 24 to 92 years, 81 healthy Caucasian male students aged from 18 to 28 years and 367 healthy Caucasian men aged from 40 to 61 years by real-time PCR. Plasma total antioxidant status (TAOS) was measured in the T2D patients by a photometric microassay. The patients were also genotyped for the UCP2 functional variants -866G>A and A55V.

RESULTS

Afro-Carribeans had 510bp longer mean length compared to Caucasians (p<0.0001) and 500bp longer than South Asians (p=0.004). T2D subjects displayed shorter age-adjusted LTL compared to controls [6.94(6.8-7.03) vs. 7.72(7.53-7.9), p<0.001] with subjects in the middle and the lowest tertile of LTL having significantly higher odds ratios for T2D compared to those in the highest tertile [1.50(1.08-2.07) and 5.04(3.63-6.99), respectively, p<0.0001]. In the patients, LTL was correlated negatively with age (r=-0.18, p<0.0001) and positively with TAOS measures (r=0.12, p=0.01) after adjusting for age, while carriers of the UCP2 -866A allele had shorter age-adjusted LTL than common homozygotes [6.86(6.76-6.96)kb vs. 7.03(6.91-7.15)kb, p=0.04].

CONCLUSION

The present data suggest that shorter LTL is associated with the presence of T2D and this could be partially attributed to the high oxidative stress in these patients. The association of the UCP2 functional promoter variant with the LTL implies a link between mitochondrial production of reactive oxygen species and shorter telomere length in T2D.

Increased polymorphonuclear leukocyte respiratory burst function in type 2 diabetes

The predisposition to infection and chronic inflammation in diabetes may in part be related to the effects of hyperglycemia or other metabolic abnormality on polymorphonuclear leukocytes (PMN). We evaluated oxidative respiratory burst activity (superoxide production) in non-stimulated and stimulated PMN from 70 stable type 2 Hispanic diabetic patients, as compared to 70 healthy Hispanic individuals without diabetes. The influences of protein kinase C (PKC) inhibitors and certain antibiotics on superoxide production were examined. Both resting and stimulated (PMA, zymosan) PMN from diabetic individuals produced more superoxide than PMN from controls. Inhibitors of PKC, a possible mediator of the augmented respiratory burst activity, decreased superoxide production in all (resting and stimulated) diabetic and control PMN. Azithromycin, which is markedly concentrated by PMN, profoundly inhibited superoxide generation in all groups of diabetic and control cells. PMN from Hispanic diabetic patients produced greater quantities of superoxide than non-diabetic controls. This increased oxidative respiratory burst activity may predispose to infection and chronic inflammation in diabetes. PKC inhibitors and azithromycin inhibited this respiratory burst response. The possible role of PKC (especially PKC beta) as the mediator of this augmented respiratory burst response requires further evaluation, and may lead to therapeutic studies with appropriate inhibitors.

Database of traditional Chinese medicine and its application to studies of mechanism and to prescription validation

BACKGROUND AND PURPOSE

Traditional Chinese Medicine (TCM) is widely practised and is viewed as an attractive alternative to conventional medicine. Quantitative information about TCM prescriptions, constituent herbs and herbal ingredients is necessary for studying and exploring TCM.

EXPERIMENTAL APPROACH

We manually collected information on TCM in books and other printed sources in Medline. The Traditional Chinese Medicine Information Database TCM-ID, at http://tcm.cz3.nus.edu.sg/group/tcm-id/tcmid.asp, was introduced for providing comprehensive information about all aspects of TCM including prescriptions, constituent herbs, herbal ingredients, molecular structure and functional properties of active ingredients, therapeutic and side effects, clinical indication and application and related matters.

RESULTS

TCM-ID currently contains information for 1,588 prescriptions, 1,313 herbs, 5,669 herbal ingredients, and the 3D structure of 3,725 herbal ingredients. The value of the data in TCM-ID was illustrated by using some of the data for an in-silico study of molecular mechanism of the therapeutic effects of herbal ingredients and for developing a computer program to validate TCM multi-herb preparations.

CONCLUSIONS AND IMPLICATIONS

The development of systems biology has led to a new design principle for therapeutic intervention strategy, the concept of 'magic shrapnel' (rather than the 'magic bullet'), involving many drugs against multiple targets, administered in a single treatment. TCM offers an extensive source of examples of this concept in which several active ingredients in one prescription are aimed at numerous targets and work together to provide therapeutic benefit. The database and its mining applications described here represent early efforts toward exploring TCM for new theories in drug discovery.

The nitric oxide-donating pravastatin derivative, NCX 6550 [(1S-[1alpha(betaS*, deltaS*), 2alpha, 6alpha, 8beta-(R*), 8a alpha]]-1,2,6,7,8,8a-Hexahydro-beta, delta, 6-trihydroxy-2-methyl-8-(2-methyl-1-oxobutoxy)-1-naphtalene-heptanoic acid 4-(nitrooxy)butyl ester)], reduces splenocyte adhesion and reactive oxygen species generation in normal and atherosclerotic mice

Statins possess anti-inflammatory effects that may contribute to their ability to slow atherogenesis, whereas nitric oxide (NO) also influences inflammatory cell adhesion. This study aimed to determine whether a novel NO-donating pravastatin derivative, NCX 6550 [(1S-[1alpha(betaS*,deltaS*),2alpha,6alpha,8beta-(R*),8a alpha]]-1,2,6,7,8,8a-hexahydro-beta,delta,6-trihydroxy-2-methyl-8-(2-methyl-1-oxobutoxy)-1-naphthalene-heptanoic acid 4-(nitrooxy)butyl ester)], has greater anti-inflammatory properties compared with pravastatin in normal and atherosclerotic apolipoprotein E receptor knockout (ApoE-/-) mice. C57BL/6 and ApoE-/- mice were administered pravastatin (40 mg/kg), NCX 6550 (48.5 mg/kg), or vehicle orally for 5 days. Ex vivo studies assessed splenocyte adhesion to arterial segments and splenocyte reactive oxygen species (ROS) generation. NCX 6550 significantly reduced splenocyte adhesion to artery segments in both C57BL/6 (8.8 +/- 1.9% versus 16.6 +/- 6.7% adhesion; P < 0.05) and ApoE-/- mice (9.3 +/- 2.9% versus 23.4 +/- 4.6% adhesion; P < 0.05) concomitant with an inhibition of endothelial intercellular adhesion molecule-1 expression. NCX 6550 also significantly reduced phorbol 12-myristate 13-acetate-induced ROS production that was enhanced in isolated ApoE-/- splenocytes. Conversely, pravastatin had no significant effects on adhesion in normal or ApoE-/- mice but reduced the enhanced ROS production from ApoE-/- splenocytes. In separate groups of ApoE-/- mice, NCX 6550 significantly enhanced endothelium-dependent relaxation to carbachol in aortic segments precon-tracted with phenylephrine (-logEC(50), 6.37 +/- 0.37) compared with both vehicle-treated (-logEC50, 5.81 +/- 0.15; P < 0.001) and pravastatin-treated (-logEC50, 5.57 +/- 0.45; P < 0.05) mice. NCX 6550 also significantly reduced plasma monocyte chemoattractant protein-1 levels (648.8 pg/ml) compared with both vehicle (1191.1 pg/ml; P < 0.001) and pravastatin (847 +/- 71.0 pg/ml; P < 0.05) treatment. These data show that NCX 6550 exerts superior anti-inflammatory actions compared with pravastatin, possibly through NO-related mechanisms.

Alpha-lipoic acid inhibits TNF-alpha-induced apoptosis in human bone marrow stromal cells

TNF-alpha is an important mediator of bone loss. In the HS-5 hBMSC, TNF-alpha and H2O2 increased intracellular ROS levels and induced cell apoptosis through activation of caspases, JNK and NF-kappaB. alpha-Lipoic acid prevented these changes induced by TNF-alpha and H2O2, suggesting its potential therapeutic applications in attenuating bone loss.

INTRODUCTION

Oxidative stress is an important mediator of bone loss. TNF-alpha, which plays a critical role in the bone loss after menopause, has been shown to increase intracellular oxidative stress. Because oxidative stress is associated with cell death, we analyzed the apoptotic effects of TNF-alpha and H2O2 on human bone marrow stromal cells (hBMSCs). We also examined the protective effects of an important biological thiol antioxidant, alpha-lipoic acid (alpha-LA), against TNF-alpha- and H2O2-induced apoptosis.

MATERIALS AND METHODS

Using the HS-5 hBMSC cell line, we tested whether TNF-alpha-induced apoptosis was mediated by the generation of excessive reactive oxygen species (ROS). Apoptosis was determined by 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) assay, trypan blue exclusion assay, quantitation of histone-associated DNA fragments in cytosol, and the activation of caspases. The mechanisms mediating these apoptotic effects were determined by Western blotting and enzyme immunoassay.

RESULTS

Both TNF-alpha and H2O2 increased intracellular ROS levels, reduced total cellular glutathione levels, activated caspases-3, -9, and -8, and enhanced hBMSC apoptosis. The activation of c-jun N-terminal kinase (JNK) and NF-kappaB mediated these apoptotic effects. Pretreatment of cells with alpha-LA prevented these changes induced by TNF-alpha and H2O2.

CONCLUSIONS

Our data show that TNF-alpha increases intracellular ROS in hBMSC and that TNF-alpha and H2O2 induce apoptosis in hBMSC through the activation of JNK and NF-kappaB. Our findings also suggest that alpha-LA may have therapeutic applications in halting or attenuating bone loss associated with increased oxidative stress.

Captopril and quinapril reduce reactive oxygen species

BACKGROUND

Angiotensin-converting enzyme inhibitors may affect reactive oxygen species in humans in vitro and in vivo. In the present study we evaluated whether angiotensin-converting enzyme inhibitors may affect NAD(P)H oxidase activity.

MATERIALS AND METHODS

The production of reactive oxygen species was measured spectrophotometrically in mononuclear leukocytes using the fluorescent dye, dichlorofluorescein diacetate. The effects of quinaprilat, captopril, enalaprilat and lisinopril on phorbol myristate acetate-induced reactive oxygen species generation were investigated in vitro. The effects of quinaprilat, captopril, enalaprilat and lisinopril on the NAD(P)H oxidase activity of the mononuclear leukocytes were measured photometrically. In addition, reactive oxygen species were measured before and 4 h after oral administration of quinapril.

RESULTS

In vitro, the addition of quinaprilat (72 +/- 6% of control; mean +/- SEM; n= 19; P < 0.001) and captopril (48 +/- 2% of control; n= 19; P < 0.001) significantly reduced the phorbol-12-myristate-13-acetate-induced reactive oxygen species generation by the mononuclear leukocytes, whereas enalaprilat and lisinopril showed no effect. The effect of captopril on phorbol-12-myristate-13-acetate-induced reactive oxygen species generation in vitro was concentration-dependent. Quinaprilat and captopril significantly inhibited the NAD(P)H oxidase activity. After the oral administration of 10 mg of quinapril the phorbol-12-myristate-13-acetate-induced reactive oxygen species generation by the mononuclear leukocytes was significantly decreased from 1981 +/- 292% to 988 +/- 141% (n = 14; P < 0.01).

CONCLUSION

Quinapril and captopril decrease the production of reactive oxygen species.

A rational approach to pathogenesis and treatment of type 2 diabetes mellitus, insulin resistance, inflammation, and atherosclerosis

Type 2 diabetes and obesity are major risk factors for the development of coronary artery disease (CAD) and premature atherosclerosis. Both conditions are associated with insulin resistance, oxidative stress, and inflammation. Inflammatory mediators, including plasma interleukin 6, tumor necrosis factor alpha, and tumor necrosis factor R are elevated in these individuals. The elevations of inflammatory mediators may contribute to the pathogenesis of atherosclerosis, because atherosclerosis is an inflammation of the arterial wall. There is evidence that the thiazolidinedione (TZD) class of drugs may alleviate some of the adverse atherosclerotic effects common in patients with type 2 diabetes. Considerable recent data suggest that the TZDs possess anti-inflammatory properties and exert an effect on the atherogenic process, including effects on endothelial function, monocyte/macrophage function, lipid abnormalities, smooth muscle cell migration, and fibrinolysis, all functions that are abnormal in the presence of insulin resistance. These actions of TZDs are consistent with the recently described anti-inflammatory effects of insulin. The use of TZDs as potent anti-inflammatory agents in patients with type 2 diabetes is an approach that would normalize glucose levels, as well as potentially alleviate the long-term risk of atherosclerosis.