Enhanced p22phox expression impairs vascular function through p38 and ERK1/2 MAP kinase-dependent mechanisms in type 2 diabetic mice

Syntheses and Applications of Coumarin-Derived Fluorescent Probes for Real-Time Monitoring of NAD(P)H Dynamics in Living Cells across Diverse Chemical Environments

Fluorescent probes play a crucial role in elucidating cellular processes, with NAD(P)H sensing being pivotal in understanding cellular metabolism and redox biology. Here, the development and characterization of three fluorescent probes, A, B, and C, based on the coumarin platform for monitoring of NAD(P)H levels in living cells are described. Probes A and B incorporate a coumarin-cyanine hybrid structure with vinyl and thiophene connection bridges to 3-quinolinium acceptors, respectively, while probe C introduces a dicyano moiety for replacement of the lactone carbonyl group of probe A which increases the reaction rate of the probe with NAD(P)H. Initially, all probes exhibit subdued fluorescence due to intramolecular charge transfer (ICT) quenching. However, upon hydride transfer by NAD(P)H, fluorescence activation is triggered through enhanced ICT. Theoretical calculations confirm that the electronic absorption changes upon the addition of hydride to originate from the quinoline moiety instead of the coumarin section and end up in the middle section, illustrating how the addition of hydride affects the nature of this absorption. Control and dose-response experiments provide conclusive evidence of probe C's specificity and reliability in identifying intracellular NAD(P)H levels within HeLa cells. Furthermore, colocalization studies indicate probe C's selective targeting of mitochondria. Investigation into metabolic substrates reveals the influence of glucose, maltose, pyruvate, lactate, acesulfame potassium, and aspartame on NAD(P)H levels, shedding light on cellular responses to nutrient availability and artificial sweeteners. Additionally, we explore the consequence of oxaliplatin on cellular NAD(P)H levels, revealing complex interplays between DNA damage repair, metabolic reprogramming, and enzyme activities. In vivo studies utilizing starved fruit fly larvae underscore probe C's efficacy in monitoring NAD(P)H dynamics in response to external compounds. These findings highlight probe C's utility as a versatile tool for investigating NAD(P)H signaling pathways in biomedical research contexts, offering insights into cellular metabolism, stress responses, and disease mechanisms.

Oxidative Regulation of Vascular Cav1.2 Channels Triggers Vascular Dysfunction in Hypertension-Related Disorders

Blood pressure is determined by cardiac output and peripheral vascular resistance. The L-type voltage-gated Ca²⁺ (Ca_v1.2) channel in small arteries and arterioles plays an essential role in regulating Ca²⁺ influx, vascular resistance, and blood pressure. Hypertension and preeclampsia are characterized by high blood pressure. In addition, diabetes has a high prevalence of hypertension. The etiology of these disorders remains elusive, involving the complex interplay of environmental and genetic factors. Common to these disorders are oxidative stress and vascular dysfunction. Reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) and mitochondria are primary sources of vascular oxidative stress, whereas dysfunction of the Ca_v1.2 channel confers increased vascular resistance in hypertension. This review will discuss the importance of ROS derived from NOXs and mitochondria in regulating vascular Ca_v1.2 and potential roles of ROS-mediated Ca_v1.2 dysfunction in aberrant vascular function in hypertension, diabetes, and preeclampsia.

Effect of sulfasalazine on endothelium-dependent vascular response by the activation of Nrf2 signalling pathway

Background: Diabetes mellitus leads to endothelial dysfunction and accumulation of oxygen radicals. Sulfasalazine-induced Nrf2 activation reduces oxidative stress in vessels. Thus, in the present study, we investigated the effects of sulfasalazine on endothelial dysfunction induced by high glucose. We also ascribed the underlying mechanism involved in glucose-induced endothelial dysfunction.

Methods: For this experiment we used 80 Wistar Albino rats thoracic aorta to calculate the dose response curve of noradrenaline and acetylcholine. Vessels were incubated in normal and high glucose for 2 h. To investigate glucose and sulfasalazine effects the vessels of the high glucose group were pre-treated with sulfasalazine (300 mM), JNK inhibitor (SP600125), and ERK inhibitor (U0126) for 30 min. The dose response curve was calculated through organ bath. The eNOS, TAS, TOS, and HO-1 levels were estimated by commercially available ELISA kits.

Results: In the high glucose group, the E_max for contraction was significantly higher (p < 0.001), and E_max for relaxation was lower than that of control. These functional changes were parallel with the low levels of eNOS (p < 0.05). High glucose vessel treated with sulfasalazine showed low E_max value for contraction (p < 0.001) however, the E_max for relaxation was significantly high (p < 0.001) when compared to high glucose group. In the JNK group, E_max for contraction and relaxation was inhibited (p < 0.001) compared to sulfasalazine treated vessels. HO—1 enzyme levels were significantly low (p < 0.01) with sulfasalazine but higher with ERK inhibitor (p < 0.05).

Conclusion: High glucose induced endothelial dysfunction and sulfasalazine reduced damage in high glucose vessels by activating eNOS, antioxidant effect through HO-1 enzymes and particularly inducing Nrf2 via the ERK and JNK pathways.

New Advances on Pathophysiology of Diabetes Neuropathy and Pain Management: Potential Role of Melatonin and DPP-4 Inhibitors

Pre-diabetes and diabetes are growing threats to the modern world. Diabetes mellitus (DM) is associated with comorbidities such as hypertension (83.40%), obesity (90.49%), and dyslipidemia (93.43%), creating a substantial burden on patients and society. Reductive and oxidative (Redox) stress level imbalance and inflammation play an important role in DM progression. Various therapeutics have been investigated to treat these neuronal complications. Melatonin and dipeptidyl peptidase IV inhibitors (DPP-4i) are known to possess powerful antioxidant and anti-inflammatory properties and have garnered significant attention in the recent years. In this present review article, we have reviewed the recently published reports on the therapeutic efficiency of melatonin and DPP-4i in the treatment of DM. We summarized the efficacy of melatonin and DPP-4i in DM and associated complications of diabetic neuropathy (DNP) and neuropathic pain. Furthermore, we discussed the mechanisms of action and their efficacy in the alleviation of oxidative stress in DM.

Disrupting Interleukin 12 Improves Microvascular Endothelial Function in Type 2 Diabetes Through ER Stress CHOP and Oxidative Stress Mechanisms

PURPOSE

Vascular endothelial dysfunction is well established in type 2 diabetes. Interleukin-12 (IL-12) and endoplasmic reticulum (ER) stress are up-regulated in type 2 diabetic patients and animal models of type 2 diabetes. However, the role and underlying mechanisms of IL-12 and the ER stress CHOP in endothelial dysfunction are not fully understood.

METHODS

We generated double knockout mice between db^-/db^- and p40IL-12^-/- mice (db^-/db^{-p40-IL-12-/-}) and endoplasmic (ER) stress-CHOP^-/- mice (db^-/db^-CHOP-/-). We performed a glucose tolerance test (GTT) to determine the effect of IL-12 and ER stress CHOP on glucose metabolism. We assessed the endothelial function and determined the phosphorylation level of eNOS, Akt, AMPK, and the expression of ER stress (CHOP, BIP), and oxidative stress (Nox2 and Nox4 and NADPH oxidase activity).

RESULTS

The results showed that GTT was improved in db-/db^{-p40-IL-12-/-} and db^-/db^-CHOP-/- suggesting IL-12 and CHOP as parts of a mechanism involved in the development of type 2 diabetes. The microvascular endothelial dysfunction in db^-/db^- mouse is associated with decreased phosphorylated eNOS, Akt, AMPK, and increased CHOP, BIP, Nox2, and Nox4 expressions. Interestingly, disrupting IL-12 and ER stress CHOP in db^-/db^- mice significantly improved endothelial function, increased survival markers expression and decreased ER and oxidative stress.

CONCLUSION

Using a genetic approach, these findings provide evidence that IL-12 and ER stress CHOP play a significant role in microvascular endothelial dysfunction in type 2 diabetes.

Pirfenidone Is a Vasodilator: Involvement of KV7 Channels in the Effect on Endothelium-Dependent Vasodilatation in Type-2 Diabetic Mice

Endothelial cell dysfunction and fibrosis are associated with worsening of the prognosis in patients with cardiovascular disease. Pirfenidone has a direct antifibrotic effect, but vasodilatation may also contribute to the effects of pirfenidone. Therefore, in a first study we investigated the mechanisms involved in the relaxant effect of pirfenidone in rat intrapulmonary arteries and coronary arteries from normal mice. Then in a second study, we investigated whether pirfenidone restores endothelial function in the aorta and mesenteric arteries from diabetic animals. From 16–18-week old normal male C57BL/6 mice and normoglycemic (db/db+), and type 2 diabetic (db/db) male and female mice, arteries were mounted in microvascular isometric myographs for functional studies, and immunoblotting was performed. In rat pulmonary arteries and mouse coronary arteries, pirfenidone induced relaxations, which were inhibited in preparations without endothelium. In mouse coronary arteries, pirfenidone relaxation was inhibited in the presence of a nitric oxide (NO) synthase inhibitor, N^G-nitro-l-arginine (L-NOARG), a blocker of large-conductance calcium-activated potassium channels (BK_Ca), iberiotoxin, and a blocker of K_V7 channels, XE991. Patch clamp studies in vascular smooth muscle revealed pirfenidone increased iberiotoxin-sensitive current. In the aorta and mesenteric small arteries from diabetic db/db mice relaxations induced by the endothelium-dependent vasodilator, acetylcholine, were markedly reduced compared to db/db + mice. Pirfenidone enhanced the relaxations induced by acetylcholine in the aorta from diabetic male and female db/db mice. An opener of K_V7 channels, flupirtine, had the same effect as pirfenidone. XE991 reduced the effect of pirfenidone and flupirtine and further reduced acetylcholine relaxations in the aorta. In the presence of iberiotoxin, pirfenidone still increased acetylcholine relaxation in aorta from db/db mice. Immunoblotting for K_V7.4, K_V7.5, and BK_Ca channel subunits were unaltered in aorta from db/db mice. Pirfenidone failed to improve acetylcholine relaxation in mesenteric arteries, and neither changed acetylcholine-induced transient decreases in blood pressure in db/db+ and db/db mice. In conclusion, pirfenidone vasodilates pulmonary and coronary arteries. In coronary arteries from normal mice, pirfenidone induces NO-dependent vasodilatation involving BK_Ca and K_V7 channels. Pirfenidone improves endothelium-dependent vasodilatation in aorta from diabetic animals by a mechanism involving voltage-gated K_V7 channels, a mechanism that may contribute to the antifibrotic effect of pirfenidone.

SGLT1 Inhibition Attenuates Apoptosis in Diabetic Cardiomyopathy via the JNK and p38 Pathway

Background: Recent studies have revealed that a novel selective sodium-glucose cotransporter 1 (SGLT1) inhibiton has shown beneficial effects in cardiovascular diseases. However, the question of whether SGLT1 inhibition influences diabetic cardiomyopathy (DCM) remains unanswered. In this study, we investigated the influence and underlying mechanism of SGLTI inhibition on DCM. Methods: SGLT1 levels were measured in diabetic patients with similar conditions who visited our hospital from January to December 2019. Wistar male rats (n = 50) were divided into five groups: control, diabetes induced by streptozotocin infusion, and diabetes treated with 0.5, 1.0, or 1.5 mg/kg mizagliflozin via stomach gavage for 12 weeks. H9C2 cardiomyocytes were treated with mizagliflozin and then exposed to a high glucose concentration (30 mmol/L). TUNEL assays were performed, and bcl2, bax, p-p38, p-Erk, p-JNK and caspase-3 levels were measured. We used siRNA and an SGLT1 overexpression plasmid to detect the effects of SGLT1. Results: SGLT1 levels were significantly elevated in DCM patients, and receiver operating characteristic (ROC) curve analysis identified SGLT1 as influencing DCM. The area under the curve (AUC) was 0.705 (p < 0.05), with 65.8% sensitivity, and 62.2% specificity. SGLT1 inhibition appeared to attenuate apoptosis in DCM via the JNK and p38 pathway. Conclusion: SGLT1 can be used as a marker for the diagnosis of DCM, and SGLT1 inhibition can attenuate apoptosis, thereby suppressing DCM development via the JNK and p38 pathway.

Endothelial Dysfunction and Passive Changes in the Aorta and Coronary Arteries of Diabetic db/db Mice

Endothelial cell dysfunction and vessel stiffening are associated with a worsened prognosis in diabetic patients with cardiovascular diseases. The present study hypothesized that sex impacts endothelial dysfunction and structural changes in arteries from diabetic mice. In diabetic (db/db) and normoglycaemic (db/db+) mice, the mechanical properties were investigated in pressurized isolated left anterior descending coronary arteries and aorta segments that were subjected to tensile testing. Functional studies were performed on wire-mounted vascular segments. The male and female db/db mice were hyperglycaemic and had markedly increased body weight. In isolated aorta segments without the contribution of smooth muscle cells, load to rupture, viscoelasticity, and collagen content were decreased suggesting larger distensibility of the arterial wall in both male and female db/db mice. In male db/db aorta segments with smooth muscle cell contribution, lumen diameter was smaller and the passive stretch-tension curve was leftward-shifted, while they were unaltered in female db/db aorta segments versus control db/db+ mice. In contrast to female db/db mice, coronary arteries from male db/db mice had altered stress-strain relationships and increased distensibility. Transthoracic echocardiography revealed a dilated left ventricle with unaltered cardiac output, while aortic flow velocity was decreased in male db/db mice. Impairment of acetylcholine relaxation was aggravated in aorta from female db/db compared to control and male db/db mice, while impairment of sodium nitroprusside relaxations was only observed in aorta from male db/db mice. The remodeling in the coronary arteries and aorta suggests an adaptation of the arterial wall to the reduced flow velocity with sex-specific differences in the passive properties of aorta and coronary arteries. The findings of less distensible arteries and more pronounced endothelial dysfunction in female compared to male diabetic mice may have implications for the observed higher incidence of macrovascular complications in diabetic women.

Effects of a Red Orange and Lemon Extract in Obese Diabetic Zucker Rats: Role of Nicotinamide Adenine Dinucleotide Phosphate Oxidase

Diabetic nephropathy (DN) is the primary cause of end-stage renal disease, worldwide, and oxidative stress has been recognized as a key factor in the pathogenesis and progression of DN. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase has the most important contribution to reactive oxygen species generation during the development of DN. Bioactive compound use has emerged as a potential approach to reduce chronic renal failure. Therefore, a red orange and lemon extract (RLE) rich in anthocyanins was chosen in our study, to reduce the toxic renal effects during the development of DN in Zucker diabetic fatty rat (ZDF). RLE effects were examined daily for 24 weeks, through gavage, in ZDF rats treated with RLE (90 mg/kg). At the end of the experiment, ZDF rats treated with RLE showed a reduction of the diabetes-associated up-regulation of both NOX4 and the p47-phox and p22-phox subunits, and restored the BAX/BCL-2 ratio respect to ZDF rats. Furthermore, RLE was able to reduce the oxidative DNA damage measured in urine samples in ZDF rats. This study showed that RLE could prevent the renal damage induced by DN through its capacity to inhibit NOX4 and apoptosis mechanisms.

Decorin inhibits glucose-induced lens epithelial cell apoptosis via suppressing p22phox-p38 MAPK signaling pathway

PURPOSE

To determine the effect of decorin on oxidative stress and apoptosis of human lens epithelial (HLE) cells under high glucose condition.

METHODS

HLE cell line (HLEB3) was incubated in normal glucose (5.5 mM) or high glucose (60 mM) medium. Decorin (50 nM) was applied 2 hours before high glucose medium was added. Apoptosis detection was executed by flow cytometry and western blotting (analysis of bcl-2 and bax). Oxidative stress level was measured by the generation of reactive oxygen species (ROS), glutathione peroxidase (GSH) and superoxide dismutase (SOD). P38 mitogen-activated protein kinase (MAPK) phosphorylation, the expression of p22phox of HLE cells and human lens anterior capsules were detected by western blotting. Small interfering RNA transfection to p22phox and p38 MAPK was also carried out on HLEB3.

RESULTS

High glucose caused HLE cells oxidative stress and apoptosis exhibiting the increase of apoptotic cells and ROS production and decrease of bcl-2/bax ratio, GSH/GSSG ration and SOD activity. P22phox and phospho-p38 MAPK were upregulated in high glucose treated HLEB3 cells. Knocking down p22phox or p38 by siRNAs can reduce high glucose induced cell apoptosis and oxidative stress level. Silencing p22phox by siRNA can downregulate the phosphorylation of p38 MAPK. Decorin can inhibit the apoptosis, oxidative stress level and the induction of p22phox and phospho-p38 of HLEB3 induced by high glucose. Furthermore, the expression of p22phox and p38 were found significantly increased in lens anterior capsules of diabetic cataract patients compared to that of normal age-related cataract patients.

CONCLUSIONS

Results showed that p22phox-p38 pathway may be participated in high glucose induced lens epithelial cell injury, decorin may inhibit the high glucose induced apoptosis and oxidative stress injury by suppressing this pathway in part.

NADPH oxidases and oxidase crosstalk in cardiovascular diseases: novel therapeutic targets

Reactive oxygen species (ROS)-dependent production of ROS underlies sustained oxidative stress, which has been implicated in the pathogenesis of cardiovascular diseases such as hypertension, aortic aneurysm, hypercholesterolaemia, atherosclerosis, diabetic vascular complications, cardiac ischaemia-reperfusion injury, myocardial infarction, heart failure and cardiac arrhythmias. Interactions between different oxidases or oxidase systems have been intensively investigated for their roles in inducing sustained oxidative stress. In this Review, we discuss the latest data on the pathobiology of each oxidase component, the complex crosstalk between different oxidase components and the consequences of this crosstalk in mediating cardiovascular disease processes, focusing on the central role of particular NADPH oxidase (NOX) isoforms that are activated in specific cardiovascular diseases. An improved understanding of these mechanisms might facilitate the development of novel therapeutic agents targeting these oxidase systems and their interactions, which could be effective in the prevention and treatment of cardiovascular disorders.

Reactive Oxygen Species in Metabolic and Inflammatory Signaling

Reactive oxygen species (ROS) are well known for their role in mediating both physiological and pathophysiological signal transduction. Enzymes and subcellular compartments that typically produce ROS are associated with metabolic regulation, and diseases associated with metabolic dysfunction may be influenced by changes in redox balance. In this review, we summarize the current literature surrounding ROS and their role in metabolic and inflammatory regulation, focusing on ROS signal transduction and its relationship to disease progression. In particular, we examine ROS production in compartments such as the cytoplasm, mitochondria, peroxisome, and endoplasmic reticulum and discuss how ROS influence metabolic processes such as proteasome function, autophagy, and general inflammatory signaling. We also summarize and highlight the role of ROS in the regulation metabolic/inflammatory diseases including atherosclerosis, diabetes mellitus, and stroke. In order to develop therapies that target oxidative signaling, it is vital to understand the balance ROS signaling plays in both physiology and pathophysiology, and how manipulation of this balance and the identity of the ROS may influence cellular and tissue homeostasis. An increased understanding of specific sources of ROS production and an appreciation for how ROS influence cellular metabolism may help guide us in the effort to treat cardiovascular diseases.

Microvascular NADPH oxidase in health and disease

The systemic and cerebral microcirculation contribute critically to regulation of local and global blood flow and perfusion pressure. Microvascular dysfunction, commonly seen in numerous cardiovascular pathologies, is associated with alterations in the oxidative environment including potentiated production of reactive oxygen species (ROS) and subsequent activation of redox signaling pathways. NADPH oxidases (Noxs) are a primary source of ROS in the vascular system and play a central role in cardiovascular health and disease. In this review, we focus on the roles of Noxs in ROS generation in resistance arterioles and capillaries, and summarize their contributions to microvascular physiology and pathophysiology in both systemic and cerebral microcirculation. In light of the accumulating evidence that Noxs are pivotal players in vascular dysfunction of resistance arterioles, selectively targeting Nox isozymes could emerge as a novel and effective therapeutic strategy for preventing and treating microvascular diseases.

Endothelial Cell Autophagy Maintains Shear Stress-Induced Nitric Oxide Generation via Glycolysis-Dependent Purinergic Signaling to Endothelial Nitric Oxide Synthase

OBJECTIVE

Impaired endothelial cell (EC) autophagy compromises shear stress-induced nitric oxide (NO) generation. We determined the responsible mechanism.

APPROACH AND RESULTS

On autophagy compromise in bovine aortic ECs exposed to shear stress, a decrease in glucose uptake and EC glycolysis attenuated ATP production. We hypothesized that decreased glycolysis-dependent purinergic signaling via P2Y1 (P2Y purinoceptor 1) receptors, secondary to impaired autophagy in ECs, prevents shear-induced phosphorylation of eNOS (endothelial nitric oxide synthase) at its positive regulatory site S1117 (p-eNOS^S1177) and NO generation. Maneuvers that restore glucose transport and glycolysis (eg, overexpression of GLUT1 [glucose transporter 1]) or purinergic signaling (eg, addition of exogenous ADP) rescue shear-induced p-eNOS^S1177 and NO production in ECs with impaired autophagy. Conversely, inhibiting glucose transport via GLUT1 small interfering RNA, blocking purinergic signaling via ectonucleotidase-mediated ATP/ADP degradation (eg, apyrase), or inhibiting P2Y1 receptors using pharmacological (eg, MRS2179 [2'-deoxy-N⁶-methyladenosine 3',5'-bisphosphate tetrasodium salt]) or genetic (eg, P2Y1-receptor small interfering RNA) procedures inhibit shear-induced p-eNOS^S1177 and NO generation in ECs with intact autophagy. Supporting a central role for PKCδ^T505 (protein kinase C delta T505) in relaying the autophagy-dependent purinergic-mediated signal to eNOS, we find that (1) shear stress-induced activating phosphorylation of PKCδ^T505 is negated by inhibiting autophagy, (2) shear-induced p-eNOS^S1177 and NO generation are restored in autophagy-impaired ECs via pharmacological (eg, bryostatin) or genetic (eg, constitutively active PKCδ) activation of PKCδ^T505, and (3) pharmacological (eg, rottlerin) and genetic (eg, PKCδ small interfering RNA) PKCδ inhibition prevents shear-induced p-eNOS^S1177 and NO generation in ECs with intact autophagy. Key nodes of dysregulation in this pathway on autophagy compromise were revealed in human arterial ECs.

CONCLUSIONS

Targeted reactivation of purinergic signaling and PKCδ has strategic potential to restore compromised NO generation in pathologies associated with suppressed EC autophagy.

Endothelial dysfunction and vascular disease - a 30th anniversary update

The endothelium can evoke relaxations of the underlying vascular smooth muscle, by releasing vasodilator substances. The best-characterized endothelium-derived relaxing factor (EDRF) is nitric oxide (NO) which activates soluble guanylyl cyclase in the vascular smooth muscle cells, with the production of cyclic guanosine monophosphate (cGMP) initiating relaxation. The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium-dependent hyperpolarizations, EDH-mediated responses). As regards the latter, hydrogen peroxide (H₂ O₂ ) now appears to play a dominant role. Endothelium-dependent relaxations involve both pertussis toxin-sensitive G_i (e.g. responses to α₂ -adrenergic agonists, serotonin, and thrombin) and pertussis toxin-insensitive G_q (e.g. adenosine diphosphate and bradykinin) coupling proteins. New stimulators (e.g. insulin, adiponectin) of the release of EDRFs have emerged. In recent years, evidence has also accumulated, confirming that the release of NO by the endothelial cell can chronically be upregulated (e.g. by oestrogens, exercise and dietary factors) and downregulated (e.g. oxidative stress, smoking, pollution and oxidized low-density lipoproteins) and that it is reduced with ageing and in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis toxin-sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and EDH, in particular those due to H₂ O₂ ), endothelial cells also can evoke contraction of the underlying vascular smooth muscle cells by releasing endothelium-derived contracting factors. Recent evidence confirms that most endothelium-dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells and that prostacyclin plays a key role in such responses. Endothelium-dependent contractions are exacerbated when the production of nitric oxide is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive and diabetic patients. In addition, recent data confirm that the release of endothelin-1 can contribute to endothelial dysfunction and that the peptide appears to be an important contributor to vascular dysfunction. Finally, it has become clear that nitric oxide itself, under certain conditions (e.g. hypoxia), can cause biased activation of soluble guanylyl cyclase leading to the production of cyclic inosine monophosphate (cIMP) rather than cGMP and hence causes contraction rather than relaxation of the underlying vascular smooth muscle.

ROS Signaling in the Pathogenesis of Acute Lung Injury (ALI) and Acute Respiratory Distress Syndrome (ARDS)

The generation of reactive oxygen species (ROS) plays an important role for the maintenance of cellular processes and functions in the body. However, the excessive generation of oxygen radicals under pathological conditions such as acute lung injury (ALI) and its most severe form acute respiratory distress syndrome (ARDS) leads to increased endothelial permeability. Within this hallmark of ALI and ARDS, vascular microvessels lose their junctional integrity and show increased myosin contractions that promote the migration of polymorphonuclear leukocytes (PMNs) and the transition of solutes and fluids in the alveolar lumen. These processes all have a redox component, and this chapter focuses on the role played by ROS during the development of ALI/ARDS. We discuss the origins of ROS within the cell, cellular defense mechanisms against oxidative damage, the role of ROS in the development of endothelial permeability, and potential therapies targeted at oxidative stress.

The Role of p38 MAPK in the Development of Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is a major complication of diabetes that contributes to an increase in mortality. A number of mechanisms potentially explain the development of DCM including oxidative stress, inflammation and extracellular fibrosis. Mitogen-activated protein kinase (MAPK)-mediated signaling pathways are common among these pathogenic responses. Among the diverse array of kinases, extensive attention has been given to p38 MAPK due to its capacity for promoting or inhibiting the translation of target genes. Growing evidence has indicated that p38 MAPK is aberrantly expressed in the cardiovascular system, including the heart, under both experimental and clinical diabetic conditions and, furthermore, inhibition of p38 MAPK activation in transgenic animal model or with its pharmacologic inhibitor significantly prevents the development of DCM, implicating p38 MAPK as a novel diagnostic indicator and therapeutic target for DCM. This review summarizes our current knowledge base to provide an overview of the impact of p38 MAPK signaling in diabetes-induced cardiac remodeling and dysfunction.

Tissue-specific up-regulation of arginase I and II induced by p38 MAPK mediates endothelial dysfunction in type 1 diabetes mellitus

BACKGROUND AND PURPOSE

Emerging evidence suggests a selective up-regulation of arginase I in diabetes causing coronary artery disease; however, the mechanisms behind this up-regulation are still unknown. Activated p38 MAPK has been reported to increase arginase II in various cardiovascular diseases. We therefore tested the role of p38 MAPK in the regulation of arginase I and II expression and its effect on endothelial dysfunction in diabetes mellitus.

EXPERIMENTAL APPROACH

Endothelial function was determined in septal coronary (SCA), left anterior descending coronary (LAD) and mesenteric (MA) arteries from healthy and streptozotocin-induced diabetic Wistar rats by wire myographs. Arginase activity and protein levels of arginase I, II, phospho-p38 MAPK and phospho-endothelial NOS (eNOS) (Ser(1177) ) were determined in these arteries from diabetic and healthy rats treated with a p38 MAPK inhibitor in vivo.

KEY RESULTS

Diabetic SCA and MA displayed impaired endothelium-dependent relaxation, which was prevented by arginase and p38 MAPK inhibition while LAD relaxation was not affected. Arginase I, phospho-p38 MAPK and eNOS protein expression was increased in diabetic coronary arteries. In diabetic MA, however, increased expression of arginase II and phospho-p38 MAPK, increased arginase activity and decreased expression of eNOS were observed. All these effects were reversed by p38 MAPK inhibition.

CONCLUSIONS AND IMPLICATIONS

Diabetes-induced activation of p38 MAPK causes endothelial dysfunction via selective up-regulation of arginase I expression in coronary arteries and arginase II expression in MA. Therefore, regional differences appear to exist in the arginase isoforms contributing to endothelial dysfunction in type 1 diabetes mellitus.

p38 MAPK in cardioprotection - are we there yet?

PKs transfer a phosphate from ATP to the side-chain hydroxyl group of a serine, threonine or tyrosine residue of a substrate protein. This in turn can alter that protein's function; modulating fundamental cellular processes including, metabolism, transcription, growth, division, differentiation, motility and survival. PKs are subdivided into families based on homology. One such group are the stress-activated kinases, which as the name suggests, are activated in response to cellular stresses such as toxins, cytokines, mechanical deformation and osmotic stress. Members include the p38 MAPK family, which is composed of α, β, γ and δ, isoforms which are encoded by separate genes. These kinases transduce extracellular signals and coordinate the cellular responses needed for adaptation and survival. However, in cardiovascular and other disease states, these same systems can trigger maladaptive responses that aggravate, rather than alleviate, the disease. This situation is analogous to adrenergic, angiotensin and aldosterone signalling in heart failure, where inhibition is beneficial despite the importance of these hormones to homeostasis. The question is whether similar benefits could accrue from p38 inhibition? In this review, we will discuss the structure and function of p38, the history of p38 inhibitors and their use in preclinical studies. Finally, we will summarize the results of recent cardiovascular clinical trials with p38 inhibitors.