The Role of Autophagy in Eosinophilic Airway Inflammation

Autophagy is a homeostatic mechanism that discards not only invading pathogens but also damaged organelles and denatured proteins via lysosomal degradation. Increasing evidence suggests a role for autophagy in inflammatory diseases, including infectious diseases, Crohn's disease, cystic fibrosis, and pulmonary hypertension. These studies suggest that modulating autophagy could be a novel therapeutic option for inflammatory diseases. Eosinophils are a major type of inflammatory cell that aggravates airway inflammatory diseases, particularly corticosteroid-resistant inflammation. The eosinophil count is a useful tool for assessing which patients may benefit from inhaled corticosteroid therapy. Recent studies demonstrate that autophagy plays a role in eosinophilic airway inflammatory diseases by promoting airway remodeling and loss of function. Genetic variant in the autophagy gene ATG5 is associated with asthma pathogenesis, and autophagy regulates apoptotic pathways in epithelial cells in individuals with chronic obstructive pulmonary disease. Moreover, autophagy dysfunction leads to severe inflammation, especially eosinophilic inflammation, in chronic rhinosinusitis. However, the mechanism underlying autophagy-mediated regulation of eosinophilic airway inflammation remains unclear. The aim of this review is to provide a general overview of the role of autophagy in eosinophilic airway inflammation. We also suggest that autophagy may be a new therapeutic target for airway inflammation, including that mediated by eosinophils.

Molecular checkpoints controlling natural killer cell activation and their modulation for cancer immunotherapy

Natural killer (NK) cells have gained considerable attention as promising therapeutic tools for cancer therapy due to their innate selectivity against cancer cells over normal healthy cells. With an array of receptors evolved to sense cellular alterations, NK cells provide early protection against cancer cells by producing cytokines and chemokines and exerting direct cytolytic activity. These effector functions are governed by signals transmitted through multiple receptor–ligand interactions but are not achieved by engaging a single activating receptor on resting NK cells. Rather, they require the co-engagement of different activating receptors that use distinct signaling modules, due to a cell-intrinsic inhibition mechanism. The redundancy of synergizing receptors and the inhibition of NK cell function by a single class of inhibitory receptor suggest the presence of common checkpoints to control NK cell activation through different receptors. These molecular checkpoints would be therapeutically targeted to harness the power of NK cells against diverse cancer cells that express heterogeneous ligands for NK cell receptors. Recent advances in understanding the activation of NK cells have revealed promising candidates in this category. Targeting such molecular checkpoints will facilitate NK cell activation by lowering activation thresholds, thereby providing therapeutic strategies that optimize NK cell reactivity against cancer.

A multifaceted approach targeting NK cells for better treatment of cancer: focus on hematological malignancies

No abstract available.

Natural Killer Cell and Cancer Immunotherapy / 한양의대학술지

Cancer remains the leading cause of death worldwide despite intense efforts in developing innovative treatments. Current approaches in cancer therapy are mainly directed to a selective targeting of cancer cells to avoid potential side effects associated with conventional therapy. In this respect, Natural killer (NK) cells have gained growing attention and are now being considered as promising therapeutic tools for cancer therapy owing to their intrinsic ability to rapidly recognize and kill cancer cells, while sparing normal healthy cells. NK cells play a key role in the first line of defense against transformed and virus-infected cells. NK cells sense their target through a whole array of receptors, both activating and inhibitory. Functional outcome of NK cell against target cells is determined by the balance of signals transmitted from diverse activating and inhibiting receptors. Despite significant progress made in the role of NK cells attack as a pivotal sentinel in tumor surveillance, the molecular has been that regulate NK cell responses remain unclear, which restricts the use of NK cells as a therapeutic measure. Accordingly, current efforts for NK cell-based cancer therapy have largely relied on the strategies that are based on the manipulation of inhibitory receptor function. However, if we better understand the mechanisms governing NK cell activation, including those mediated by diverse activating receptors, this knowledge can be applied to the development of optimal design for cancer immunotherapy by targeting NK cells.

High K(+)-Induced Relaxation by Nitric Oxide in Human Gastric Fundus

This study was designed to elucidate high K(+)-induced relaxation in the human gastric fundus. Circular smooth muscle from the human gastric fundus greater curvature showed stretch-dependent high K+ (50 mM)-induced contractions. However, longitudinal smooth muscle produced stretch-dependent high K(+)-induced relaxation. We investigated several relaxation mechanisms to understand the reason for the discrepancy. Protein kinase inhibitors such as KT 5823 (1 microM) and KT 5720 (1 microM) which block protein kinases (PKG and PKA) had no effect on high K(+)-induced relaxation. K+ channel blockers except 4-aminopyridine (4-AP), a voltage-dependent K+ channel (KV) blocker, did not affect high K(+)-induced relaxation. However, N(G)-nitro-L-arginine and 1H-(1,2,4)oxadiazolo (4,3-A)quinoxalin-1-one, an inhibitors of soluble guanylate cyclase (sGC) and 4-AP inhibited relaxation and reversed relaxation to contraction. High K(+)-induced relaxation of the human gastric fundus was observed only in the longitudinal muscles from the greater curvature. These data suggest that the longitudinal muscle of the human gastric fundus greater curvature produced high K(+)-induced relaxation that was activated by the nitric oxide/sGC pathway through a KV channel-dependent mechanism.

Signaling for Synergistic Activation of Natural Killer Cells

Natural killer (NK) cells play a pivotal role in early surveillance against virus infection and cellular transformation, and are also implicated in the control of inflammatory response through their effector functions of direct lysis of target cells and cytokine secretion. NK cell activation toward target cell is determined by the net balance of signals transmitted from diverse activating and inhibitory receptors. A distinct feature of NK cell activation is that stimulation of resting NK cells with single activating receptor on its own cannot mount natural cytotoxicity. Instead, specific pairs of co-activation receptors are required to unleash NK cell activation via synergy-dependent mechanism. Because each co-activation receptor uses distinct signaling modules, NK cell synergy relies on the integration of such disparate signals. This explains why the study of the mechanism underlying NK cell synergy is important and necessary. Recent studies revealed that NK cell synergy depends on the integration of complementary signals converged at a critical checkpoint element but not on simple amplification of the individual signaling to overcome intrinsic activation threshold. This review focuses on the signaling events during NK cells activation and recent advances in the study of NK cell synergy.

Mechanical Stretch-Induced Protection against Myocardial Ischemia-Reperfusion Injury Involves AMP-Activated Protein Kinase

AMP-activated protein kinase (AMPK) protects various tissues and cells from ischemic insults and is activated by many stimuli including mechanical stretch. Therefore, this study investigated if the activation of AMPK is involved in stretch-induced cardioprotection (SIC). Intraventricular balloon and aorto-caval shunt (ACS) were used to stretch rat hearts ex vivo and in vivo, respectively. Stretch preconditioning reduced myocardial infarct induced by ischemia-reperfusion (I/R) and improved post-ischemic functional recovery. Phosphorylation of AMPK and its downstream substrate, acetyl-CoA carboxylase (ACC) were increased by mechanical stretch and ACC phosphorylation was completely blocked by the AMPK inhibitor, Compound C. AMPK activator (AICAR) mimicked SIC. Gadolinium, a blocker of stretch-activated ion channels (SACs), inhibited the stretch-induced phosphorylation of AMPK and ACC, whereas diltiazem, a specific L-type calcium channel blocker, did not affect AMPK activation. Furthermore, SIC was abrogated by Compound C and gadolinium. The in vivo stretch induced by ACS increased AMPK activation and reduced myocardial infarct. These findings indicate that stretch preconditioning can induce the cardioprotection against I/R injury, and activation of AMPK plays an important role in SIC, which might be mediated by SACs.

Regional Distribution of Interstitial Cells of Cajal, (ICC) in Human Stomach

We elucidated the distribution of interstitial cells of Cajal (ICC) in human stomach, using cryosection and c-Kit immunohistochemistry to identify c-Kit positive ICC. Before c-Kit staining, we routinely used hematoxylin and eosin (HE) staining to identify every structure of human stomach, from mucosa to longitudinal muscle. HE staining revealed that the fundus greater curvature (GC) had prominent oblique muscle layer, and c-Kit immunostaining c-Kit positive ICC cells were found to have typical morphology of dense fusiform cell body with multiple processes protruding from the central cell body. In particular, we could observe dense processes and ramifications of ICC in myenteric area and longitudinal muscle layer of corpus GC. Interestingly, c-Kit positive ICC-like cells which had morphology very similar to ICC were found in gastric mucosa. We could not find any significant difference in the distribution of ICC between fundus and corpus, except for submucosa where the density of ICC was much higher in gastric fundus than corpus. Furthermore, there was no significant difference in the density of ICC between each area of fundus and corpus, except for muscularis mucosa. Finally, we also found similar distribution of ICC in normal and cancerous tissue obtained from a patient who underwent pancreotomy and gastrectomy. In conclusion, ICC was found ubiquitously in human stomach and the density of ICC was significantly lower in the muscularis mucosa of both fundus/corpus and higher in the submucosa of gastric fundus than corpus.

Effects of Advanced Glycation Endproducts (AGE) on Rat Glomerular Epithelial Cells (GEC): Roles of Reactive Oxygen Species (ROS) / 대한신장학회잡지

BACKGROUND: AGE-induced oxidative stress is implicated in the development and progression of diabetic nephropathy. AGE also affect the GEC to increase their permeability, therefore, we investigate the possibility that AGE may induce oxidative stress and subsequent injury to GEC. METHODS: We cultured rat GEC on the AGE- or BSA-coated plate with high glucose (HG) to produce more pathophysiologic conditions similar to prolonged diabetic environment in vivo and measured the change of ROS and their anti-oxidants systems. We also evaluated the effects of probucol as an antioxidant on this system. RESULTS: The amount of superoxide anion slightly decreased on AGE condition without significance. However, the production of hydrogen peroxide was significantly enhanced by 10% on AGE-coated and HG condition compared to control (BSA-coated and 5 mM glucose) (p< 0.05) and hydroxyl radical have also showed similar increase on AGE-coated and HG condition by 10% above control (p< 0.01), and both increases were attenuated by probucol (both, p< 0.05). The activity of superoxide dismutase (SOD) was decreased by 10% on AGE-coated and HG condition (p< 0.05) and recovered by probucol partially. However, there were no significant changes on the activity of other anti-oxidant enzymes including catalase, glutathione peroxidase, and glutathione reductase. Therefore, glomerular epithelial injury presenting proteinuria may be provoked by hydrogen peroxide and subsequently increased hydroxyl radical induced by AGE and high glucose. CONCLUSION: We might assume that superoxide had been converted to hydrogen peroxide by consumptive SOD in the presence of AGE, and subsequently produced hydroxyl radical, which could be reversed by anti-oxidant, may induce diabetic glomerular epithelial injury and eventually proteinuria.

Value of Urinary 8-hydroxydeoxyguanosine (oh(8)dG) Measurement in Patients with Bladder Cancer / 대한비뇨기과학회지

PURPOSE: Oxidative DNA damage may play a role in the aging process, carcinogenesis and other degenerative diseases and can be assessed in humans in vivo from the urinary excretion of the DNA repair product, 8-hydroxydeoxyguanosine (oh(8)dG). In order to estimate the urinary oh(8)dG concentration in bladder cancer patients and the effect of smoking on the urinary oh(8)dG excretion, the urinary oh(8)dG levels in bladder cancer patients and control subjects were measured. MATERIALS AND METHODS: Urine samples were collected from 110 bladder cancer patients and 64 controls. The subjects' smoking history was gathered from a standardized self-completed questionnaire. The urinary oh(8)dG concentration was measured using an oh(8)dG ELISA Kit. The relationship between the urinary oh(8)dG concentration and the bladder cancer stage, grade and smoking history were analyzed. RESULTS: The urinary oh(8)dG concentration was significantly higher in the control group than in both preoperative and postoperative bladder cancer patients (p=0.049 and p=0.013, respectively). In the bladder cancer patients, the urinary oh(8)dG concentration did not correlate with either the stage or the grade. Regarding the smoking status, the urinary oh(8)dG concentrations of smokers in bladder cancer patients were lower than those of smokers in the control group (p=0.018). In the control group, the urinary oh(8)dG concentrations in smokers were higher than those in nonsmokers (p=0.013). There was no difference of urinary oh(8)dG concentration in bladder cancer patients irrespective of the smoking status. CONCLUSIONS: The decreased urinary excretion of oh(8)dG in bladder tumor patients suggests that the repair mechanism of oxidative DNA damage, oh(8)dG, might be impaired in bladder cancer patients. Further studies aimed at measuring the DNA concentration of oh(8)dG or its repair activity in bladder tumor tissues are needed to test this possibility.

Value of Urinary 8-hydroxydeoxyguanosine (oh(8)dG) Measurement in Patients with Bladder Cancer / 대한비뇨기과학회지

PURPOSE: Oxidative DNA damage may play a role in the aging process, carcinogenesis and other degenerative diseases and can be assessed in humans in vivo from the urinary excretion of the DNA repair product, 8-hydroxydeoxyguanosine (oh(8)dG). In order to estimate the urinary oh(8)dG concentration in bladder cancer patients and the effect of smoking on the urinary oh(8)dG excretion, the urinary oh(8)dG levels in bladder cancer patients and control subjects were measured. MATERIALS AND METHODS: Urine samples were collected from 110 bladder cancer patients and 64 controls. The subjects' smoking history was gathered from a standardized self-completed questionnaire. The urinary oh(8)dG concentration was measured using an oh(8)dG ELISA Kit. The relationship between the urinary oh(8)dG concentration and the bladder cancer stage, grade and smoking history were analyzed. RESULTS: The urinary oh(8)dG concentration was significantly higher in the control group than in both preoperative and postoperative bladder cancer patients (p=0.049 and p=0.013, respectively). In the bladder cancer patients, the urinary oh(8)dG concentration did not correlate with either the stage or the grade. Regarding the smoking status, the urinary oh(8)dG concentrations of smokers in bladder cancer patients were lower than those of smokers in the control group (p=0.018). In the control group, the urinary oh(8)dG concentrations in smokers were higher than those in nonsmokers (p=0.013). There was no difference of urinary oh(8)dG concentration in bladder cancer patients irrespective of the smoking status. CONCLUSIONS: The decreased urinary excretion of oh(8)dG in bladder tumor patients suggests that the repair mechanism of oxidative DNA damage, oh(8)dG, might be impaired in bladder cancer patients. Further studies aimed at measuring the DNA concentration of oh(8)dG or its repair activity in bladder tumor tissues are needed to test this possibility.

Effects of Eligh Glucose and Advance Gilycosylation Endproducts(AGE) on the Heparan Sulfate Proteoglycan(HSPG) Produced by Cultured Rat Clomerular Epithelial Cells(GEC) / 대한신장학회잡지

HSPG, a component of size-and charge-selective barrier of glomerular basement membrane, is one of important matrix proteins which has been known to be reduced in the kidney of diabetic patients or animals. To examine the effects of glucose and AGE on the HSPG production by cultured GEC, we cultured rat GEC on the AGE- or BSA-coated plate under normal(5mM) and high glucose.(30mM) conditions and measured the change of HSPG production by sandwich-ELISA assay and northern blot analysis at 2 days and one week incubation periods. There was no difference in proliferation between 2 different conditions of culture plate surface. We measured the relative amount of the extracted HSPC and observed significant decreases in high glucose condition at one week incubation, and particularly on the AGE-coated surface as compared to the results of BSA-coated condition, by 22% and 5%, respectively. The expression of mRNA for perlecan promoter was decreased in condition of high glucose and AGE-coated surface by 20Yo at 2 days and 61i at one week. Even in normal glucose condition, the expression of mRNA was reduced by 30Yo at one week if the plate was coated with AGE. In conclusion, both high glucose and AGE have reducing effects on the production of HSPG by GEC in vitro. Their effects seem to be additive, however, the role of AGE is greater than that of glucose, This means that the effort to inhibit AGE formation is more important than short-term glucose control for the prevention of diabetic proteinuria.

Effects of Exposure to Hexavalent Chromium on the Level of 8-Hydroxydeoxyguanosine and the Activities of Superoxide Dismutase and 8-Hydroxyguanine Endonuclease in Rat Lung / 예방의학회지

OBJECTIVES: To determine the effects of exposure to hexavalent chromium, 93 male Sprague-Dawley rats were exposed to hexavalent chromium solution. METHODS: Rats were divided into 4 groups and exposed to 0.1 ml of 0 mM, 0.4 mM, 2.0 mM, and 10.0 mM potassium chromate in the first experiment, and to 0.1 ml of 0 mM, 20 mM, 40 mM, and 80 mM in the second for consecutive 3 days by tracheal instillation. Three and 10 rats were the controls for the first and the second experiments, respectively. Lung tissues were then removed to measure the 8-hydroxydeoxyguanosine (8-OH-dG) level using the HPLC-ECD method, superoxide dismutase (SOD) activity using the cytochrome C method, and 8-hydroxyguanine endonuclease activity using the oligonucleotide nicking assay. RESULTS: The results showed no significant linear relationship between chromium exposure level and 8-OH-dG level or 8-hydroxyguanine endonuclease activity. In the first experiment, 8-OH-dG level and 8-hydroxyguanine endonuclease activity increased in 0.4 mM group, and then decreased in 2.0 mM and 10.0 mM groups. The correlation coefficients between 8-OH-dG level and 8-hydroxyguanine endonuclease activity was statistically significant (P<0.01), and total SOD activity was elevated by chromium exposure in a dose-dependent manner (P<0.05). In contrast, there was no significant dose-response pattern or correlation in the second experiment. CONCLUSIONS: Based on the fact that there was no linear relationship between chromium dose and 8-OH-dG level or activity of the repair enzyme, it seems unlikely that 8-OH-dG formation is the major mechanism of chromium carcinogenesis.

Inhibitory effects of ginseng saponins on c-fos mRNA expression and the proliferation of rat aortic vascular smooth muscle cells stimulated by angiotensin II

To evaluate the possibility that the ginseng saponins could be developed as an anti-arteriosclerotic agent, we examined the inhibitory effects of ginseng saponins (total saponin(TS), panaxatriol(PT), panaxadiol(PD)) on the expression of c-fos mRNA and the proliferation of cultured rat aortic vascular smooth muscle cells (VSMCs) stimulated by angiotensin II (Ang II). TS and PT (1.0 mg/ml) suppressed c-fos mRNA induction in VSMCs stimulated by 10-5 M Ang II. The order of inhibitory potency was PT>TS. Ginseng saponins (0.01~1.0 mg/ml) inhibited the proliferation of VSMCs stimulated by Ang II in a concentration dependent manner, the inhibitory potency was TS> PT> PD at 0.1~1.0 mg/ml. These results suggest that ginseng saponins may suppress Ang II-stimulated proliferation of aortic VSMCs which can be seen in atherosclerosis, hypertension and restenosis.