Overexpressed nuclear factor kappaB correlates with enhanced expression of interleukin-1beta and inducible nitric oxide synthase in aged murine lungs to endotoxic stress

Shared and specific biological signalling pathways for diabetic retinopathy, peripheral neuropathy and nephropathy by high-throughput sequencing analysis

OBJECTIVES

We aimed to explore the shared and specific signalling pathways involved in diabetic retinopathy (DR), diabetic peripheral neuropathy (DPN) and diabetic nephropathy (DN).

METHODS

Differentially expressed mRNAs and lncRNAs were identified by high-throughput sequencing. Subsequently, functional enrichment analysis, protein-protein interaction (PPI) analysis and lncRNAs-mRNAs networks were conducted to determine the pathogenic mechanisms underlying DR, DPN and DN.

RESULTS

Twenty-six biological pathways were shared among DR, DPN and DN groups compared to the type 2 diabetes mellitus (T2DM) group without complications, and most of the shared pathways and core proteins were involved in immune and inflammatory responses of microvascular damage. Cytokine‒cytokine receptor interactions and chemokine signalling pathway were the most significant and specific pathways for DR, and the lncRNA‒mRNA regulatory networks affected DR by targeting these pathways. Sphingolipid metabolism and neuroactive ligand-receptor pathways were found to be specific for the pathogenesis of DPN. Moreover, multiple amino acid metabolic pathways were involved in the occurrence and progression of DN.

CONCLUSIONS

Diabetic retinopathy, DPN and DN exhibited commonality and heterogeneity simultaneously. The shared pathologic mechanisms underlying these diabetic complications are involved in diabetic microvascular damage via immune and inflammatory pathways. Our findings predict several biomarkers and therapeutic targets for these diabetic complications.

Luo Tong formula attenuates retinal inflammation in diabetic rats via inhibition of the p38MAPK/NF-κB pathway

Background

Diabetic retinopathy (DR) is a serious microvascular complication of diabetes and remains the leading cause of blindness in adults. Retinal inflammation is playing a crucial role in the development of DR, and targeting inflammatory mediators is a promising strategy for controlling DR. Here, we investigated compound Chinese medicine Luo Tong formula (LTF) alleviated retinal inflammatory responses in a STZ-induced diabetic rat model.

Methods

Sprague–Dawley rats were divided into four groups: control, streptozotocin-induced diabetic, LTF-treated diabetic, and calcium dobesilate (CaD)-treated diabetic rats. Blood samples were collected for blood glucose examination. Hematoxylin–eosin and periodic acid-Schiff staining were conducted for light microscopy observations. Retinal cell apoptosis was detected using the TUNEL assay. Proteins expression was quantified by Western blotting and/or immunohistochemistry, and gene expression was assessed by real-time PCR.

Results

Diabetic rats showed significant increases in the expression of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), nuclear factor-κB (NF-κB), and the phospho-p38 mitogen-activated protein kinase (p-p38-MAPK)/p38 MAPK ratio compared to control rats. LTF treatment significantly improved both retinal and pancreatic pathological injury, LTF treatment also inhibited inducible the p-p38 MAPK/p38 MAPK ratio and NF-κB activation and decreased the subsequent induction of the retinal expression of proinflammatory mediators TNF-α, IL-1β, MCP-1 and ICAM-1 compared to diabetic rats. LTF also exhibited a protective effect on islet function.

Conclusions

LTF before the onset of DR can alleviate retinal pathological injury, LTF may play an anti-inflammatory role by inhibiting p38-MAPK and then inhibiting NF-κB pathway. But further studies are needed to confirm this conclusion.

Trial registration This is an animal experiment, trial registration is not necessary.

Remodeling of Retinal Architecture in Diabetic Retinopathy: Disruption of Ocular Physiology and Visual Functions by Inflammatory Gene Products and Pyroptosis

Diabetic patients suffer from a host of physiological abnormalities beyond just those of glucose metabolism. These abnormalities often lead to systemic inflammation via modulation of several inflammation-related genes, their respective gene products, homocysteine metabolism, and pyroptosis. The very nature of this homeostatic disruption re-sets the overall physiology of diabetics via upregulation of immune responses, enhanced retinal neovascularization, upregulation of epigenetic events, and disturbances in cells' redox regulatory system. This altered pathophysiological milieu can lead to the development of diabetic retinopathy (DR), a debilitating vision-threatening eye condition with microvascular complications. DR is the most prevalent cause of irreversible blindness in the working-age adults throughout the world as it can lead to severe structural and functional remodeling of the retina, decreasing vision and thus diminishing the quality of life. In this manuscript, we attempt to summarize recent developments and new insights to explore the very nature of this intertwined crosstalk between components of the immune system and their metabolic orchestrations to elucidate the pathophysiology of DR. Understanding the multifaceted nature of the cellular and molecular factors that are involved in DR could reveal new targets for effective diagnostics, therapeutics, prognostics, preventive tools, and finally strategies to combat the development and progression of DR in susceptible subjects.

Aerobic Glycolysis Hypothesis Through WNT/Beta-Catenin Pathway in Exudative Age-Related Macular Degeneration

Exudative age-related macular degeneration (AMD) is characterized by molecular mechanisms responsible for the initiation of choroidal neovascularization (CNV). Inflammatory processes are associated with upregulation of the canonical WNT/beta-catenin pathway in exudative AMD. We focus this review on the link between WNT/beta-catenin pathway activation and neovascular progression in exudative AMD through activation of aerobic glycolysis for production of angiogenic factors. Increased WNT/beta-catenin pathway involves hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2). WNT/beta-catenin pathway stimulates PI3K/Akt pathway and then HIF-1alpha which activates glycolytic enzymes: glucose transporter (Glut), pyruvate dehydrogenase kinase 1 (PDK1), lactate dehydrogenase A (LDH-A), and monocarboxylate lactate transporter (MCT-1). This phenomenon is called aerobic glycolysis or the Warburg effect. Consequently, phosphorylation of PDK-1 inhibits the pyruvate dehydrogenase complex (PDH). Thus, a large part of pyruvate cannot be converted into acetyl-CoA in mitochondria and only a part of acetyl-CoA can enter the tricarboxylic acid cycle. Cytosolic pyruvate is converted into lactate through the action of LDH-A. In exudative AMD, high level of cytosolic lactate is correlated with increase of VEGF expression, the angiogenic factor of CNV. Photoreceptors in retina cells can metabolize glucose through aerobic glycolysis to protect them against oxidative damage, as cancer cells do.

Oxidative stress, mitochondrial damage and diabetic retinopathy

Diabetes has emerged as an epidemic of the 21st century, and retinopathy remains the leading cause of blindness in young adults and the mechanism of this blinding disease remains evasive. Diabetes-induced metabolic abnormalities have been identified, but a causal relationship between any specific abnormality and the development of this multi-factorial disease is unclear. Reactive oxygen species (ROS) are increased and the antioxidant defense system is compromised. Increased ROS result in retinal metabolic abnormalities, and these metabolic abnormalities can also produce ROS. Sustained exposure to ROS damages the mitochondria and compromises the electron transport system (ETC), and, ultimately, the mitochondrial DNA (mtDNA) is damaged. Damaged mtDNA impairs its transcription, and the vicious cycle of ROS continues to propagate. Many genes important in generation and neutralization of ROS are also epigenetically modified further increasing ROS, and the futile cycle continues to fuel in. Antioxidants have generated beneficial effects in ameliorating retinopathy in diabetic rodents, but limited clinical studies have not been encouraging. With the ongoing use of antioxidants for other chronic diseases, there is a need for a controlled trial to recognize their potential in ameliorating the development of this devastating disease.

Exogenous H2S protects H9c2 cardiac cells against high glucose-induced injury and inflammation by inhibiting the activation of the NF-κB and IL-1β pathways

Hyperglycemia has been reported to activate the nuclear factor-κB (NF-κB) pathway. We have previously demonstrated that exogenous hydrogen sulfide (H2S) protects cardiomyocytes against high glucose (HG)-induced injury by inhibiting the activity of p38 mitogen-activated protein kinase (MAPK), which can activate the NF-κB pathway and induce interleukin (IL)-1β production. In the present study, we aimed to investigate the hypothesis that exogenous H2S protects cardiomyocytes against HG-induced injury and inflammation through the inhibition of the NF-κB/IL-1β pathway. H9c2 cardiac cells were treated with 35 mM glucose (HG) for 24 h to establish a model of HG-induced damage. Our results demonstrated that treatment of the cells with 400 µM sodium hydrogen sulfide (NaHS, a donor of H2S) or 100 µM pyrrolidine dithiocarbamate (PDTC, an inhibitor of NF-κB) for 30 min prior to exposure to HG markedly attenuated the HG-induced increase in the expression levels of the phosphorylated (p)-NF-κB p65 subunit. Notably, pre-treatment of the H9c2 cardiac cells with NaHS or PDTC significantly suppressed the HG-induced injury, including cytotoxicity, apoptosis, oxidative stress and mitochondrial insults, as evidenced by an increase in cell viability, as well as a decrease in the number of apoptotic cells, the expression of cleaved caspase-3, the generation of reactive oxygen species (ROS) and the dissipation of mitochondrial membrane potential (MMP). In addition, pre-treatment of the cells with NaHS or PDTC ameliorated the HG-induced inflammatory response, leading to a decrease in the levels of IL-1β, IL-6 and tumor necrosis factor-α (TNF-α). Importantly, co-treatment of the H9c2 cells with 20 ng/ml IL-1 receptor antagonist (IL-1Ra) and HG markedly reduced the HG-induced increase in p-NF-κB p65 expression, cytotoxicity, the number of apoptotic cells, as well as the production of TNF-α. In conclusion, the present study presents novel mechanistic evidence that exogenous H2S protects H9c2 cardiac cells against HG-induced inflammation and injury, including cytotoxicity, apoptosis, overproduction of ROS and the dissipation of MMP, by inhibiting the NF-κB/IL-1β pathway. We also provide new data indicating that the positive interaction between the NF-κB pathway and IL-1β is critical in HG-induced injury and inflammation in H9c2 cardiac cells.

Age-Associated Increase in Cytokine Production During Systemic Inflammation-II: The Role of IL-1β in Age-Dependent IL-6 Upregulation in Adipose Tissue

Expression of interleukin-6 (IL-6) upon acute inflammatory stress is significantly augmented by aging in adipose tissue, a major source of this cytokine. In the present study, we examined the mechanism of age-dependent IL-6 overproduction using visceral white adipose tissue from C57BL/6 mice. Upon treatment with lipopolysaccharide (LPS) in vitro, IL-6 was produced by adipose tissue explants, and secreted levels were significantly higher in cultures from aged (24 months) mice compared to young (4 months). Interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNFα), two inducers of IL-6, were mainly produced by the lungs and spleen rather than adipose tissue in mice after LPS injection. Treatment of adipose explants with physiological levels of IL-1β induced significant age-dependent secretion of IL-6, while treatment with TNFα had little effect, demonstrating an augmented response of adipose tissues to IL-1β in the aged. In vitro experiments utilizing a neutralizing antibody against IL-1β and in vivo experiments utilizing IL-1-receptor-1 deficient mice, confirmed that IL-6 overproduction in the aged is regulated by autocrine/paracrine action of IL-1β which specifically occurs in aged adipose tissues. These findings indicate an elevated inflammatory potential of adipose tissue in the aged and a unique IL-1β-mediated mechanism for IL-6 overproduction, which may impact age-associated vulnerability to acute inflammatory diseases such as sepsis.

Effects of N-adamantyl-4-methylthiazol-2-amine on hyperglycemia, hyperlipidemia and oxidative stress in streptozotocin-induced diabetic rats

Thiazole derivatives are attractive candidates for drug development because they can be efficiently synthesized and are active against a number of diseases and conditions, including diabetes. In our present study, we investigated the anti-inflammatory and antioxidant properties of N-adamantyl-4-methylthiazol-2-amine (KHG26693), a new thiazole derivative, in a streptozotocin (STZ)-induced model of diabetes mellitus. STZ-induced diabetic rats were intraperitoneally administered KHG26693 (3mg/kg-body weight/day) for 4 weeks. KHG26693 administration significantly decreased blood glucose, triglycerides, and cholesterol and increased insulin. KHG26693 also suppressed several inflammatory responses in STZ-induced diabetic rats, as evidenced by decreased levels of serum tumor necrosis factor-α, interleukin-1β, and nitric oxide. Additionally, KHG26693 significantly modulated hepatic lipid peroxidation, catalase and superoxide dismutase activity, and the nonenzymatic antioxidant status (e.g., vitamins C and E), and reduced the glutathione content. These anti-inflammatory/antioxidative actions occurred as a result of the downregulation of inducible nitric oxide synthase and nuclear factor-kappa B. Taken together, our results suggest that KHG26693 successfully reduces the production of oxidative stress in STZ-induced diabetic rats by regulating the oxidation-reduction system, specifically increasing antioxidant capacity. Furthermore, KHG26693 treatment significantly reverted the key enzymes of glucose metabolism, such as glucokinase, glucose-6-phosphatase, glycogen synthase, glycogen phosphorylase, and fructose-1,6-bisphosphatase, to near-normal levels in liver tissues. These results indicate that KHG26693 normalizes disturbed glucose metabolism by enhancing glucose utilization and decreasing liver glucose production via insulin release, suggesting the possibility of future diabetes treatments.

Role of matrix metalloproteinase-2 and -9 in the development of diabetic retinopathy

Diabetic retinopathy represents the most common causes of vision loss in patients affected by diabetes mellitus. The cause of vision loss in diabetic retinopathy is complex and remains incompletely understood. One of the earliest changes in the development of retinopathy is the accelerated apoptosis of retinal microvascular cells and the formation of acellular capillaries by unknown mechanism. Results of a recent research suggest an important role of matrix metalloproteinases (MMPs) in the development of diabetic retinopathy. MMPs are a large family of proteinases that remodel extracellular matrix components, and under pathological condition, its induction is considered as a negative regulator of cell survival; and in diabetes, latent MMPs are activated in the retina and its capillary cells, and activation of MMP-2 and -9 induces apoptosis of retinal capillary cells. This review will focus on the MMP-2 and MMP-9 in the diabetic retina with special reference to oxidative stress, mitochondria dysfunction, inflammation and angiogenesis, as well as summarizing the current information linking these proteins to pathogenesis of diabetic retinopathy.

Resistance of retinal inflammatory mediators to suppress after reinstitution of good glycemic control: novel mechanism for metabolic memory

Diabetic retinopathy resists arrest of its progression after reestablishment of good glycemic control that follows a profound period of poor glycemic control. The objective of this study was to elucidate the role of inflammation in the resistance of retinopathy to arrest after termination of hyperglycemia. Streptozotocin-diabetic rats were (a) maintained either in poor glycemic control [PC group; glycated hemoglobin (GHb)>11%] or in good glycemic control (GC group; GHb<7%) for 12 months or (b) allowed to be in poor glycemic control for 6 months followed by good glycemic control for 6 additional months. At 12 months, retina was analyzed for pro-inflammatory mediators. Twelve months of PC increased retinal interleukin 1beta (IL-1beta) mRNA by 2-fold and its protein expression by 25% compared with the values obtained from normal rat retina. Tumor necrosis factor alpha (TNF-alpha) was elevated approximately 3-fold (both mRNA and protein), and the receptors for IL-1beta and TNF-alpha were increased by 40% each. The concentrations of intercellular cell adhesion molecule 1 and vascular cell adhesion molecule 1 were elevated by 40% and 150%, respectively, and inducible nitric oxide synthase transcripts were elevated by 6-fold. Six months of good glycemic control that followed 6 months of poor glycemic control failed to reverse the elevations in IL-1beta, TNF receptor type I, and intercellular cell adhesion molecule 1 but had some beneficial effects on TNF-alpha, inducible nitric oxide synthase, and vascular cell adhesion molecule 1, however these mediators remained significantly elevated. However, the GC group showed no significant change in the retinal pro-inflammatory mediators compared with the normal rats. Failure to reverse retinal inflammatory mediators supports their important role in the resistance of retinopathy to arrest after cessation of hyperglycemia.

The pathogenic role of the canonical Wnt pathway in age-related macular degeneration

PURPOSE

The authors' previous studies showed that the Wnt signaling pathway is activated in the retinas and retinal pigment epithelia of animal models of age-related macular degeneration (AMD) and diabetic retinopathy (DR). The purpose of this study was to investigate the role of the canonical Wnt pathway in pathogenesis of these diseases.

METHODS

The Wnt pathway was activated using the Wnt3a-conditioned medium and adenovirus expressing a constitutively active mutant of beta-catenin (Ad-S37A) in ARPE19, a cell line derived from human RPE. Ad-S37A was injected into the vitreous of normal rats to activate the Wnt pathway in the retina. Accumulation of beta-catenin was determined by Western blot analysis, and its nuclear translocation was revealed by immunocytochemistry. Inflammatory factors were quantified by Western blot analysis and ELISA. Oxidative stress was determined by measuring intracellular reactive oxygen species (ROS) generation and nitrotyrosine levels.

RESULTS

The Wnt3a-conditioned medium and Ad-S37A both increased beta-catenin levels and its nuclear translocation in ARPE19 cells, suggesting activation of the canonical Wnt pathway. Activation of the Wnt pathway significantly upregulated the expression of VEGF, NF-kappaB, and TNF-alpha. Further, Ad-S37A induced ROS generation in a dose-dependent manner. Wnt3a also induced a twofold increase of ROS generation. Intravitreal injection of Ad-S37A upregulated the expression of VEGF, ICAM-1, NF-kappaB, and TNF-alpha and increased protein nitrotyrosine levels in the retinas of normal rats.

CONCLUSIONS

Activation of the canonical Wnt pathway is sufficient to induce retinal inflammation and oxidative stress and plays a pathogenic role in AMD and DR.

Aging enhances susceptibility to cigarette smoke-induced inflammation through bronchiolar chemokines

Cigarette smoking and aging are major risk factors for chronic obstructive pulmonary disease. An unsolved question is whether elderly lungs are particularly vulnerable to cigarette smoke (CS) exposure. In this study, we used a mouse model to test the hypothesis that aging increases the susceptibility to CS-induced pulmonary inflammation. We subjected 9-week-old and 69-week-old C57BL/6J mice to CS (whole-body exposure, 90 min/d), and evaluated neutrophil infiltration in the lungs, the levels of keratinocyte-derived chemokine (KC) and macrophage inflammatory protein (MIP)-2 in bronchoalveolar lavage fluid, and mRNA expression in bronchiolar epithelium retrieved by laser capture microdissection. The 69-week-old mice showed a greater number of neutrophils and higher levels of bronchiolar KC and MIP-2 expression than 9-week-old mice after 9 days of CS exposure. Furthermore, single CS exposure induced the rapid up-regulation of KC and MIP-2 in bronchiolar epithelium in both 9-week-old and 69-week-old mice, and the much higher levels in 69-week-old mice were associated with greater nuclear translocation of NF-kappaB. In contrast, no age-related differences were observed in the bronchiolar expression of NF-E2-related factor 2-regulated antioxidant and detoxification genes, heme oxygenase-1, reduced nicotinamide adenine dinucleotide phosphate quinone reductase 1, and glutamate-cysteine ligase, modifier unit, or antioxidant activity in bronchoalveolar lavage fluid, regardless of CS exposure. In summary, aging increases susceptibility to CS-induced inflammation in a mouse model, and robust mRNA up-regulation and nuclear translocation of NF-kappaB in bronchiolar epithelium may be involved.

Exercise training modulates the nitric oxide synthase profile in skeletal muscle from old rats

The effects of exercise training on the nitric oxide synthase (NOS) isoform profile in aging fast-twitch (white gastrocnemius [WG]) and slow-twitch (soleus [SOL]) muscle have not been investigated. Six-month and 27-month male Fischer-344 rats were divided into the following groups: young sedentary (YS), young treadmill exercise trained for 12 weeks, old sedentary (OS), and old exercise trained (OE). Inducible NOS (iNOS) protein expression and activity were significantly higher in OS compared with YS, whereas exercise training significantly reduced iNOS protein and activity levels in the WG. Neuronal NOS protein expression decreased with aging in WG but was upregulated significantly with exercise training in OE for both WG and SOL. Endothelial NOS (eNOS) protein levels were depressed in WG of old rats but were higher in OE than in OS. eNOS was unaffected by aging or exercise in the SOL. Our results indicate that endurance exercise training attenuates age-induced alterations of NOS isoforms with a greater response in fast-twitch compared with slow-twitch muscle.

Oxidative stress and diabetic retinopathy

Oxygen metabolism is essential for sustaining aerobic life, and normal cellular homeostasis works on a fine balance between the formation and elimination of reactive oxygen species (ROS). Oxidative stress, a cytopathic consequence of excessive production of ROS and the suppression of ROS removal by antioxidant defense system, is implicated in the development of many diseases, including Alzheimer's disease, and diabetes and its complications. Retinopathy, a debilitating microvascular complication of diabetes, is the leading cause of acquired blindness in developed countries. Many diabetes-induced metabolic abnormalities are implicated in its development, and appear to be influenced by elevated oxidative stress; however the exact mechanism of its development remains elusive. Increased superoxide concentration is considered as a causal link between elevated glucose and the other metabolic abnormalities important in the pathogenesis of diabetic complications. Animal studies have shown that antioxidants have beneficial effects on the development of retinopathy, but the results from very limited clinical trials are somewhat ambiguous. Although antioxidants are being used for other chronic diseases, controlled clinical trials are warranted to investigate potential beneficial effects of antioxidants in the development of retinopathy in diabetic patients.

Effects of curcumin on retinal oxidative stress and inflammation in diabetes

BACKGROUND

Oxidative stress and inflammation are implicated in the pathogenesis of retinopathy in diabetes. The aim of this study is to examine the effect of curcumin, a polyphenol with antioxidant and anti-inflammatory properties, on diabetes-induced oxidative stress and inflammation in the retina of rats.

METHODS

A group of streptozotocin-induced diabetic rats received powdered diet supplemented with 0.05% curcumin (w/w), and another group received diet without curcumin. The diets were initiated soon after induction of diabetes, and the rats were sacrificed 6 weeks after induction of diabetes. The retina was used to quantify oxidative stress and pro-inflammatory markers.

RESULTS

Antioxidant capacity and the levels of intracellular antioxidant, GSH (reduced form of glutathione) levels were decreased by about 30-35%, and oxidatively modified DNA (8-OHdG) and nitrotyrosine were increased by 60-70% in the retina of diabetic rats. The levels of interleukin-1beta (IL-1beta) and vascular endothelial growth factor (VEGF) were elevated by 30% and 110% respectively, and the nuclear transcription factor (NF-kB) was activated by 2 fold. Curcumin administration prevented diabetes-induced decrease in the antioxidant capacity, and increase in 8-OHdG and nitrotyrosine; however, it had only partial beneficial effect on retinal GSH. Curcumin also inhibited diabetes-induced elevation in the levels of IL-1beta, VEGF and NF-kB. The effects of curcumin were achieved without amelioration of the severity of hyperglycemia.

CONCLUSION

Thus, the beneficial effects of curcumin on the metabolic abnormalities postulated to be important in the development of diabetic retinopathy suggest that curcumin could have potential benefits in inhibiting the development of retinopathy in diabetic patients.

Extracellular human thioredoxin-1 inhibits lipopolysaccharide-induced interleukin-1beta expression in human monocyte-derived macrophages

Oxidative stress plays an important role in atherosclerotic vascular disease, and several recent studies were focused on thioredoxin-1 (Trx-1) and its potential protective role against oxidative stress. Since human monocyte-derived macrophages (HMDM) are important cells in several inflammatory diseases including atherosclerosis, we conducted this study to evaluate the impact of extracellular recombinant human Trx-1 (rhTrx-1) on gene expression in lipopolysaccharide-activated HMDM. Our results showed that rhTrx-1 was capable of reducing interleukin (IL)-1beta mRNA and protein synthesis in a dose-dependent manner. This effect was partly mediated through a reduction of NF-kappaB activation as analyzed by transient transfection and gel shift assays. In addition, we showed that the attenuation of NF-kappaB activity was the result of the reduction of both p50 and p65 subunit mRNA and protein synthesis on one hand and of the induction of I-kappaBalpha mRNA and protein expression on the other hand. Moreover, inhibition of endogenous Trx-1 mRNA was also observed, suggesting a contribution to the diminution of NF-kappaB activity since endogenous Trx-1, in contrast to the exogenous Trx-1, activates the NF-kappaB system. Finally, H2O2-oxidized rhTrx-1 reduced IL-1beta mRNA synthesis in lipopolysaccharide-activated HMDM. This result highly suggested that the rhTrx-1 used in this study could be oxidized in the culture medium and, in turn, reduced IL-1beta mRNA and protein synthesis. Taken together, these data indicated a potential new mechanism through which extracellular rhTrx-1 exerts an anti-inflammatory function in HMDM.

Involvement of nitric oxide-mediated intrinsic pathway signaling in age-related increase in germ cell apoptosis in male Brown-Norway rats

We examined, using young and old Brown-Norway rats, the involvement of the nitric oxide (NO)-mediated intrinsic pathway signaling in age-related activation of male germ-cell apoptosis. Increased apoptosis of germ cells was readily observed in the normal-looking testes of old rats. Testicular NO synthase (NOS) activity, assessed by measuring the synthesis of (3)H-L-citrulline from (3)H-L-arginine, and cytokine-inducible NO synthase (iNOS) levels, assessed by western blot assay, were increased significantly by 90% and 70%, respectively, in the old rats compared to that of young animals. Immunohistochemical analysis of age-related changes in the expression of iNOS in testes confirmed our findings based on western blot assay. Increased NO and germ-cell apoptosis during aging is further associated with cytosolic translocation of mitochondrial cytochrome c and poly (ADP) ribose polymerase (PARP) cleavage, thus, suggesting the involvement of NO-mediated intrinsic pathway signaling in age-related increase in germ-cell apoptosis in male Brown-Norway rats.

Divergent contractile and structural responses of the murine PKC-epsilon null pulmonary circulation to chronic hypoxia

Loss of PKC-epsilon limits the magnitude of acute hypoxic pulmonary vasoconstriction (HPV) in the mouse. Therefore, we hypothesized that loss of PKC-epsilon would decrease the contractile and/or structural response of the murine pulmonary circulation to chronic hypoxia (Hx). However, the pattern of lung vascular responses to chronic Hx may or may not be predicted by the acute HPV response. Adult PKC-epsilon wild-type (PKC-epsilon(+/+)), heterozygous null, and homozygous null (PKC-epsilon(-/-)) mice were exposed to normoxia or Hx for 5 wk. PKC-epsilon(-/-) mice actually had a greater increase in right ventricular (RV) systolic pressure, RV mass, and hematocrit in response to chronic Hx than PKC-epsilon(+/+) mice. In contrast to the augmented PA pressure and RV hypertrophy, pulmonary vascular remodeling was increased less than expected (i.e., equal to PKC-epsilon(+/+) mice) in both the proximal and distal PKC-epsilon(-/-) pulmonary vasculature. The contribution of increased vascular tone to this pulmonary hypertension (PHTN) was assessed by measuring the acute vasodilator response to nitric oxide (NO). Acute inhalation of NO reversed the increased PA pressure in hypoxic PKC-epsilon(-/-) mice, implying that the exaggerated PHTN may be due to a relative deficiency in nitric oxide synthase (NOS). Despite the higher PA pressure, chronic Hx stimulated less of an increase in lung endothelial (e) and inducible (i) NOS expression in PKC-epsilon(-/-) than PKC-epsilon(+/+) mice. In contrast, expression of nNOS in PKC-epsilon(+/+) mice decreased in response to chronic Hx, while lung levels in PKC-epsilon(-/-) mice remained unchanged. In summary, loss of PKC-epsilon results in increased vascular tone, but not pulmonary vascular remodeling in response to chronic Hx. Blunting of Hx-induced eNOS and iNOS expression may contribute to the increased vascular tone. PKC-epsilon appears to be an important signaling intermediate in the hypoxic regulation of each NOS isoform.