Transcription factor NF-kappa B is necessary for up-regulation of type 1 angiotensin II receptor mRNA in rat cardiac fibroblasts treated with tumor necrosis factor-alpha or interleukin-1 beta

Improving the titer of recombinant adenovirus by suppressing problematic transgene transcription during packaging

A new strategy to package "problematic" transgenes in adenovirus was developed that was based on modifications of the tetracycline-inducible system. This strategy used two components: the adenoviral genome containing the transgene under control of a hybrid TRE promoter/SV40 enhancer and a trans-encoded tTS suppressor Using luciferase reporters, expression of tTS in 293A cells reduced transcription from the promoter/enhancer 25-fold. Procaspase 8 adenovirus was then tested, since it is known to package poorly with standard adenoviral systems. Expression of tTS in 293A cells increased the titer of procaspase 8 adenovirus by 22-fold in initial viral packaging (using transiently transfected tTS) and 9-fold in subsequent viral reamplification (using 293A cells stably expressing tTS). The Tac antigen gene (i.e., CD25), which packages in adenovirus without difficulty, was also tested as a control. In contrast to that observed with procaspase 8, tTS expression did not alter the titer obtained when packaging the CD25 gene, thus excluding nonspecific effects of tTS expression on adenoviral titer Since tTS was provided in trans and did not package in the resulting adenoviruses, strong transcription of the transgenes occurred in transducted cells without the need of additional reagents.

NMR Assessment of Me2SO in Decellularized Cryopreserved Aortic Valve Conduits

INTRODUCTION

Decellularized cryopreserved allograft vascular tissue may provide a nonimmunogenic scaffold that is suitable for repopulation by cells from a variety of sources, conferring the potential for growth and repair. Although dimethyl sulfoxide (Me(2)SO) is generally regarded as a safe cryoprotectant, even low levels may alter function of repopulating cells. We investigated the residual concentration of Me(2)SO in the aqueous compartment of cryopreserved ovine aortic valve conduits following decellularization.

MATERIALS AND METHODS

Aortic valve conduits from Suffolk sheep were cryopreserved in 1.1 M (7.5% vol/vol) Me(2)SO according to the protocol of our local tissue bank. Three aortic valve conduits were decellularized in a series of hypotonic and hypertonic Tris buffers. Tissue samples were taken at regular time intervals throughout the decellularization process and equilibrated in double distilled, deionized H(2)O for 28 days. Quantitative proton nuclear magnetic resonance spectroscopy was used to determine the residual Me(2)SO concentration in the equilibration solutions from which Me(2)SO tissue concentrations were calculated.

RESULTS

After thawing, the mean Me(2)SO concentration in the valve conduit was 0.302 +/- 0.081 M. The decellularization process resulted in a stepwise reduction in the Me(2)SO concentration to less than 8.56 x 10(-5) +/- 9 x 10(-5) M (P = 0.02). The diffusion coefficient was 2.5 x 10(-6) cm(2)/s.

CONCLUSIONS

Our study demonstrates that Me(2)SO is effectively washed out of the aortic valve conduit during decellularization, resulting in a final concentration that is several orders of magnitude less than Me(2)SO concentrations reported to alter cell function.

Central gene transfer of interleukin-10 reduces hypothalamic inflammation and evidence of heart failure in rats after myocardial infarction

The expression of proinflammatory cytokines increases in hypothalamus of rats with myocardial infarction (MI) and heart failure. We used central gene transfer of human interleukin (IL)-10, a potent antiinflammatory cytokine, to counter the effects of brain proinflammatory cytokines and examine their functional significance. Sprague-Dawley rats underwent coronary ligation to induce MI or sham surgery (SHAM). One week later, adenoviral vectors encoding human IL-10 (AdIL-10) or beta-galactosidase (betaGal) were injected (30 microL over 30 minutes) into lateral ventricle. One week after injection, there was abundant expression of human IL-10 in the brain of MI+AdIL-10 and SHAM+AdIL-10 rats. Compared with SHAM+betaGal, MI+betaGal had increased (P<0.05) IL-1beta and cyclooxygenase-2 mRNA and protein and nuclear factor kappaB activity in the hypothalamus, cyclooxygenase-2 fluorescence in perivascular cells of the paraventricular nucleus of hypothalamus, prostaglandin E(2) in cerebrospinal fluid, and Fra-like activity (indicating neuronal excitation) in paraventricular nucleus. Plasma norepinephrine levels, lung/body weight, right ventricle/body weight, and left ventricular end-diastolic pressure were increased and maximal left ventricular dP/dt was decreased. All of these findings were ameliorated in MI rats treated with AdIL-10. Hypothalamic tumor necrosis factor-alpha and circulating tumor necrosis factor-alpha and IL-1beta levels, also increased in MI+betaGal, were not affected by AdIL-10 treatment. Rat native IL-10 was not affected by MI or AdIL-10. AdIL-10 had no effects on SHAM rats. The results demonstrate that cardiovascular and autonomic mechanisms leading to heart failure after MI can be modulated by manipulating the balance between proinflammatory and antiinflammatory cytokines in the brain.

Role of the renin-angiotensin system in ventilator-induced lung injury: an in vivo study in a rat model

BACKGROUND

Injurious mechanical ventilation can cause a pro-inflammatory reaction in the lungs. Recent evidence suggests an association of the renin-angiotensin system (RAS) with lung inflammation. A study was undertaken to investigate the pathogenic role of the RAS in ventilator-induced lung injury (VILI) and to determine whether VILI can be attenuated by angiotensin converting enzyme (ACE) inhibition.

METHODS

Male Sprague-Dawley rats were mechanically ventilated for 4 h with low (7 ml/kg) or high (40 ml/kg) tidal volumes; non-ventilated rats were used as controls. Lung injury and inflammation were measured by the lung injury score, protein leakage, myeloperoxidase activity, pro-inflammatory cytokine levels and nuclear factor (NF)-kappaB activity. Expression of the RAS components was also assessed. Some rats were pretreated with the ACE inhibitor captopril (10 mg/kg) for 3 days or received a concomitant infusion with losartan or PD123319 (type 1 or type 2 angiotensin II receptor antagonist) during mechanical ventilation to assess possible protective effects on VILI.

RESULTS

In the high-volume group (n=6) the lung injury score, bronchoalveolar lavage fluid protein concentration, pro-inflammatory cytokines and NF-kappaB activities were significantly increased compared with controls (n=6). Lung tissue angiotensin II levels and mRNA levels of angiotensinogen and type 1 and type 2 angiotensin II receptors were also significantly increased in the high-volume group. Pretreatment with captopril or concomitant infusion with losartan or PD123319 in the high-volume group attenuated the lung injury and inflammation (n=6 for each group).

CONCLUSIONS

The RAS is involved in the pathogenesis of ventilator-induced lung injury. ACE inhibitor or angiotensin receptor antagonists can attenuate VILI in this rat model.

Inhibition of NF-κB improves left ventricular remodeling and cardiac dysfunction after myocardial infarction

Several studies have demonstrated that NF-κB is substantially involved in the progression of cardiac remodeling; however, it remains uncertain whether the continuous inhibition of NF-κB is effective for the prevention of myocardial remodeling. Myocardial infarction (MI) was produced by ligation of the left anterior coronary artery of rats. IMD-0354 (10 mg/kg per day), a novel phosphorylation inhibitor of IκB that acts via inhibition of IKK-β, was injected intraperitoneally starting 24 h after induction of MI for 28 days. After 28 days, the IMD-0354-treated group showed significantly improved survival rate compared with that of the vehicle-treated group ( P < 0.05). Although infarct size was similar in both groups, improved left ventricular (LV) remodeling and diastolic dysfunction, as indicated by smaller LV cavity (LV end-diastolic area: vehicle, 74.13 ± 3.57 mm2; IMD-0354, 55.00 ± 3.73 mm2; P < 0.05), smaller peak velocity of early-to-late filling wave (E/A) ratio (vehicle, 3.87 ± 0.26; IMD-0354, 2.61 ± 0.24; P < 0.05), and lower plasma brain natriuretic peptide level (vehicle, 167.63 ± 14.87 pg/ml; IMD-0354, 110.75 ± 6.41 pg/ml; P < 0.05), were observed in the IMD-0354-treated group. Moreover, fibrosis, accumulation of macrophages, and expression of several factors (transforming growth factor-β1, monocyte chemoattractant protein-1, matrix metalloproteinase-9 and -2) in the noninfarcted myocardium was remarkably inhibited by IMD-0354. In conclusion, inhibition of NF-κB activation may reduce the proinflammatory reactions and modulate the extracellular matrix and provide an effective approach to prevent adverse cardiac remodeling after MI.

Centrally administered interleukin-1 beta sensitizes to the central pressor action of angiotensin II

The objective of the present study was to find out whether brain vasopressin (AVP) and angiotensin II (Ang II) are involved in pressor response to intracerebroventricular (ICV) infusion of interleukin-1 beta (IL-1beta). The experiments were performed on conscious, 12- to 14-week-old Sprague-Dawley rats. Mean arterial blood pressure (MAP) and heart rate (HR) were recorded continuously under baseline conditions and during ICV infusion periods. In the first part of the study, the rats were ICV-infused with one of the following: 0.9% NaCl saline (5 microl/h-control), IL-1beta (100 ng/h), angiotensin AT1 receptor antagonist (losartan 10 microg/h), IL-1beta together with losartan, V1 receptors antagonist (V1ANT), d(CH2)5[Tyr(Me)2,Ala-NH2(9)]AVP, 400 ng/h) or IL-1beta together with V1ANT. Saline infusion did not influence MAP, while administration of IL-1beta elicited a significant but transient increase in MAP. The pressor response to IL-1beta was abolished by losartan but not by V1ANT. On the other hand, combined administration of IL-1beta and V1ANT resulted in increase in HR, which was absent during infusion of IL-1beta alone. In the second part of the study after ICV pretreatment with IL-1beta or 0.9% NaCl (control), the rats received ICV infusion of one of the following: 0.9% NaCl saline, subpressor dose of Ang II (5 ng/15 s) or subpressor dose of AVP (5 ng/15 s). Subpressor doses of Ang II and AVP did not influence MAP and HR in saline-pretreated rats. The same dose of Ang II but not AVP applied in IL-1beta-pretreated rats resulted in a significant increase in MAP. The study provides evidence that IL-1beta through its action in the brain increases sensitivity to central pressor action of Ang II. Additionally, we found that AVP and in particular V1 receptors do not play important role in the central pressor action of IL-1beta, however, they may influence its effect on HR regulation.

Blockade of angiotensin II AT1 receptors inhibits pressor action of centrally administered interleukin-1beta in Sprague Dawley rats

The aim of the present study was to evaluate the influence of intraventricular administration of recombinant rat interleukin-1beta (IL-1beta) on regulation of resting blood pressure and heart rate and to test the hypothesis that the brain angiotensinergic system is involved in regulation of hemodynamic parameters by centrally applied IL-1beta. The experiments were performed on Sprague Dawley rats, assigned to three series of experiments. In series 1 (control, n = 6), mean arterial pressure (MAP) and heart rate (HR) were recorded for 15 min under baseline conditions. This was followed by infusion of saline (0.9% sterile NaCl 5 microL/h) into the left cerebral ventricle (LCV). Measurements were continued during the next 60 min. In series 2 (n = 6) and 3 (n = 6) the experimental design was similar, except that in series 2 the animals were LCV infused with saline containing IL-1beta (100 ng/h) and in series 3 with saline containing IL-1beta (100 ng/h) and angiotensin type 1 (AT1) receptors antagonist (Losartan, 10 microg/h). LCV infusion of saline alone did not influence MAP and HR while administration of IL-1beta elicited significant increase in MAP, but not in HR. The pressor effect was absent during combined infusion of IL-1beta and Losartan. Results of the study provide evidence that centrally administered IL-1beta exerts pressor effect, and reveal that this effect is mediated by stimulation of the brain angiotensin system and requires activation of AT1 receptors.

IL-17 reduces TNF-induced Rantes and VCAM-1 expression

Functional diversity of the memory T-cell-derived cytokine IL-17 was explored at the receptor level. IL-17 inhibited TNF-induced chemokine Rantes expression in human synovial fibroblasts and mouse lung fibroblasts. This inhibitory activity of IL-17 (IC50=0.2 ng/ml) was 6-fold more potent than its stimulatory activity on TNF-alpha-induced IL-6 secretion (ED50=1.2 ng/ml), measured in the same cells. IL-17 also inhibited the TNF-mediated expression of adhesion molecule VCAM-1, and the NF-kappaB binding to the VCAM-1 promoter-specific site, along with the inhibitor of NF-kappaB, IkappaB-beta. Neutralization of the human IL-17 receptor (IL-17R) by M202 antibody competitively reverses the IL-17-induced IL-6 upregulation. However, M202 only partially affected the inhibitions by IL-17. Yet, IL-17R was essential for the Rantes inhibition, as assessed in lung-derived fibroblasts from IL-17R gene deficient mice. Therefore, inhibitory and stimulatory functions of IL-17 involve receptor IL-17R but show distinct dose-responses and in turn different sensitivities to an IL-17R antagonizing antibody.

Angiotensin-(1-7) binds to specific receptors on cardiac fibroblasts to initiate antifibrotic and antitrophic effects

ANG-(1-7) improves the function of the remodeling heart. Although this peptide is generated directly within the myocardium, the effects of ANG-(1-7) on cardiac fibroblasts that play a critical role in cardiac remodeling are largely unknown. We tested the hypothesis that specific binding of ANG-(1-7) to cardiac fibroblasts regulates cellular functions that are involved in cardiac remodeling. 125I-labeled ANG-(1-7) binding assays identified specific binding sites of ANG-(1-7) on adult rat cardiac fibroblasts (ARCFs) with an affinity of 11.3 nM and a density of 131 fmol/mg protein. At nanomolar concentrations, ANG-(1-7) interacted with specific sites that were distinct from ANG II type 1 and type 2 receptors without increasing cytosolic Ca2+ concentration. At these concentrations, ANG-(1-7) had inhibitory effects on collagen synthesis as assessed by [3H]proline incorporation and decreased mRNA expression of growth factors in ARCFs. These effects of ANG-(1-7) contrasted with effects of ANG II. Pretreatment of ARCFs with ANG-(1-7) inhibited ANG II-induced increases in collagen synthesis and in mRNA expression of growth factors, including endothelin-1 and leukemia inhibitory factor. ANG-(1-7) pretreatment also inhibited the stimulatory effects of conditioned medium from ANG II-treated ARCFs on [3H]leucine incorporation and atrial natriuretic factor mRNA expression, markers of hypertrophy, in cardiomyocytes. Thus ANG-(1-7) interacted with specific receptors on ARCFs to exert potential antifibrotic and antitrophic effects that could reverse ANG II effects. These results suggest that ANG-(1-7) may play an important role in the heart in regulating cardiac remodeling.

Effects of cytokine treatment on angiotensin II type 1A receptor transcription and splicing in rat cardiac fibroblasts

Angiotensin II (ANG II) plays important roles in cardiac extracellular matrix remodeling via its type 1A (AT(1A)) receptor. The cytokines tumor necrosis factor-alpha and interleukin-1beta (IL-1beta) were shown previously to upregulate AT(1A) receptor mRNA and protein, thereby increasing the profibrotic response to ANG II in cardiac fibroblasts. The present experiments implicate increased nuclear factor-kappaB (NF-kappaB)-dependent transcription and also, to a lesser extent, altered mRNA splicing in the mechanism of receptor upregulation. Cytokine stimulation was found to increase AT(1A) heterogeneous nuclear RNA levels, which strongly suggests that mRNA upregulation occurs transcriptionally. The transcription factor NF-kappaB was previously deemed necessary for cytokine-induced AT(1A) receptor mRNA upregulation. Computer analysis of upstream DNA sequences revealed putative NF-kappaB elements at -365 and -2540 bp. Both isolated elements were shown to bind NF-kappaB (using gel-shift assays) and to transactivate a minimal promoter (using reporter assays), although the element at -365 bp appeared stronger. Three splice variants of AT(1A) receptor mRNA that have different 5' untranslated regions were detected in rat tissues, namely, exons 1-2-3 (predominant), 1-2-3+6, and 1-3. Cytokine treatment of fibroblasts upregulated all splice variants, but exon 1-3 increased more than the others. This differential upregulation, albeit of modest magnitude, was statistically significant with IL-1beta treatment. Exon 2 contains an inhibitory minicistron and a predicted inhibitory hairpin structure. Luciferase reporter assays indicated that each splice variant translates at a different efficiency, with exon 1-2-3+6 (both minicistron and hairpin) < exon 1-2-3 (minicistron only) < exon 1-3 (neither minicistron or hairpin). These results provide evidence that cytokines increase AT(1) protein levels by altering both transcription and splicing.

The cannabinoid dexanabinol is an inhibitor of the nuclear factor-kappa B (NF-kappa B)

Exogenous and endogenous cannabinoids have been shown to have neuroprotective effects in vitro and in vivo. Although many of the pharmacological effects of cannabinoids have been identified, the mechanism of neuroprotection still represents a controversy. Here we demonstrate for the first time protective effects of the synthetic cannabinoid dexanabinol by inhibiting apoptosis in a neuron-like cell line using nuclear staining and FACS analysis and in primary neurons. We provide further evidence of inhibition of nuclear factor-kappakappa B (NF-kappaB) by dexanabinol: Dexanabinol inhibits (1) phosphorylation and degradation of the inhibitor of NF-kappaB IkappaBalpha and translocation of NF-kappaB to the nucleus; dexanabinol reduces (2) the transcriptional activity of NF-kappaB and (3) mRNA accumulation of the NF-kappaB target genes tumor necrosis factor-alpha and interleukin-6 (TNF-alpha and IL-6). Dexanabinol does not bind to cannabinoid (CB) receptors 1 and 2. To investigate the mechanism of action, we employed the non-antioxidant CB1 receptor agonist WIN 55,212-2 and the antioxidant cannabinol, which binds to CB1 receptors only weakly. Both cannabinoids mimicked the effect of dexanabinol on NF-kappaB and apoptosis. This suggests that neither the antioxidant properties of cannabinoids nor binding to CB1 or CB2 receptors are responsible for the inhibition of NF-kappaB activity and apoptosis. Our results clearly demonstrate that dexanabinol inhibits NF-kappaB. NF-kappaB has been shown to be involved in brain damage and to promote neuronal cell death in vitro and in in vivo models of ischemic and neurodegenerative neurological diseases.

Tumor necrosis factor alpha system in the bovine oviduct: a possible mechanism for embryo transport

Active contractile pattern of the oviduct occurs during the periovulatory period for the movement of the gamete/embryo, which is strictly regulated by endocrine and paracrine/autocrine factors. In this review, an involvement of tumor necrosis factor alpha (TNFalpha) in the regulation of cow oviductal contraction is discussed. Oviductal epithelial cells express TNFalpha ligand and it's both receptor types; high expression during the follicular and postovulatory stages, while low expression during luteal stage and thus, TNFalpha system in the cow oviduct is most active during the periovulatory period. The immune cells present in large numbers in the oviduct during the periovulatory period of the estrus cycle, and these cells are also considered as another potential source for the TNFalpha in the oviduct. Using in vitro models, TNFalpha clearly stimulated local production and release of contraction related substances such as prostaglandins (PGs), endothelin-1 (ET-1) and angiotensin II (Ang II). Since these substances have been shown to activate directly the oviductal contraction in vitro, TNFalpha appears to stimulate the oviductal contraction during the periovulatory period and contribute to create an optimal local environment suitable for gamete/embryo transport. In addition, the ability of embryo to act as a source of TNFalpha in the oviduct cannot be excluded. To support this idea, the embryo at 2-4 cells stages indeed express TNFalpha, so that the minute quantities of TNFalpha secreted by the embryo may further acts locally to enhance the production of PG, ET-1 and Ang II in the oviduct, which may result in an active oviductal contraction in the microenvironment around the embryo. This may ensure the embryo to migrate into the uterus at the optimal time.

Attenuation of virus-induced myocardial injury by inhibition of the angiotensin II type 1 receptor signal and decreased nuclear factor-kappa B activation in knockout mice

OBJECTIVES

This study examined the role of angiotensin II (Ang-II) in a murine model of viral myocarditis.

BACKGROUND

Ang-II plays an important role in the pathophysiology of various cardiovascular disorders. However, the role of Ang-II in inflammatory heart diseases is not known.

METHODS

Four-week-old wild-type (WT) and Ang-II type 1 receptor (AT(1)R) knockout (KO) mice were inoculated with the encephalomyocarditis virus (EMCV). Survival, histopathology, expression of proinflammatory cytokines, and activity of nuclear factor-kappa B (NF-kB) in the heart were examined.

RESULTS

The 14-day survival was significantly increased in KO compared with WT mice. Histopathologic scores for myocardial necrosis (0.86 +/- 0.69 vs. 2.44 +/- 0.88, p < 0.01) and cellular infiltration (0.86 +/- 0.38 vs. 2.33 +/- 0.50, p < 0.01) were lower in KO than in WT mice. The expression of tumor necrosis factor-alpha (TNF-alpha) was increased 43.2-fold, that of interleukin-1-beta (IL-1-beta) 45.8-fold, and the activity of NF-kB 2.24-fold by EMCV inoculation in WT mice (each p < 0.01), but not in KO mice (5.9-fold, 6.3-fold, and 1.12-fold, respectively, each p = NS). The AT(1)R blocker also significantly attenuated the expression of proinflammatory cytokines and the activation of NF-kB in virus-inoculated WT mice. Intravenous Ang-II injection enhanced the activation of NF-kB (2.28-fold, p < 0.01) and increased the expression of TNF-alpha (2.31-fold, p < 0.01) and IL-1-beta (2.45-fold, p < 0.01) in heart tissue of WT but not KO mice.

CONCLUSIONS

These results indicate that the AT(1)R signal is obligatory for the development of virus-induced myocardial injury through the proinflammatory action of Ang-II via the NF-kB/cytokine pathway.

Tumor necrosis factor alpha in the bovine oviduct during the estrous cycle: messenger RNA expression and effect on secretion of prostaglandins, endothelin-1, and angiotensin II

Tumor necrosis factor (TNF) alpha is an important physiological mediator of cell-to-cell communication. Recent observations suggest that TNFalpha is involved in the control of reproductive functions. The present study examined the role of TNFalpha in the secretion of factors involved in regulating smooth muscle contraction, such as prostaglandin E2 (PGE2), prostaglandin F2alpha (PGF2alpha), endothelin-1 (ET-1), and angiotensin II (Ang II), as it was in the original by the cow oviduct at different stages of the estrous cycle using an in vitro microdialysis system. Expression of mRNA for TNFalpha and its receptors (TNFalpha-R) was also evaluated. For microdialysis, the lumen of a portion (length, 10 cm) of the each oviductal segment was implanted with a dialysis capillary membrane, and TNFalpha (100 ng/ml) was infused for 4-8 h during a 16-h incubation period. The microdialysis system maintains cell-to-cell integrity and cell-to-cell communication, and it enables real-time observation of physiological changes in the luminal release of different substances. Concentrations of PG, ET-1, and Ang II in 4-h fractions were measured using second-antibody enzyme immunoassays. Infusion of TNFalpha stimulated oviductal secretion of PG, ET-1, and Ang II during the follicular and postovulatory stages, but not during the luteal stage. Expression of TNFalpha, TNFalpha-R type I, and TNFalpha-R type II mRNA was detected in the bovine oviduct by reverse transcription-polymerase chain reaction. High expression of both TNFalphaR types and ligands was detected during the follicular and postovulatory stages, whereas low expression was detected during the luteal stage. The results of the present study provide, to our knowledge, the first direct evidence that TNFalpha stimulates PG, ET-1, and Ang II secretion and that up-regulation of the TNFalpha system occurs in the cow oviduct during the periovulatory period. In conclusion, the TNFalpha system may optimize the release of contraction-related substances and modulate local contraction to regulate the oviductal transport of the gametes and embryo.

Anti-inflammatory effects of angiotensin II AT1 receptor antagonism prevent stress-induced gastric injury

Stress reduces gastric blood flow and produces acute gastric mucosal lesions. We studied the role of angiotensin II in gastric blood flow and gastric ulceration during stress. Spontaneously hypertensive rats were pretreated for 14 days with the AT1 receptor antagonist candesartan before cold-restraint stress. AT1 receptors were localized in the endothelium of arteries in the gastric mucosa and in all gastric layers. AT1 blockade increased gastric blood flow by 40-50%, prevented gastric ulcer formation by 70-80% after cold-restraint stress, reduced the increase in adrenomedullary epinephrine and tyrosine hydroxylase mRNA without preventing the stress-induced increase in adrenal corticosterone, decreased the stress-induced expression of TNF-alpha and that of the adhesion protein ICAM-1 in arterial endothelium, decreased the neutrophil infiltration in the gastric mucosa, and decreased the gastric content of PGE2. AT1 receptor blockers prevent stress-induced ulcerations by a combination of gastric blood flow protection, decreased sympathoadrenal activation, and anti-inflammatory effects (with reduction in TNF-alpha and ICAM-1 expression leading to reduced neutrophil infiltration) while maintaining the protective glucocorticoid effects and PGE2 release. Angiotensin II has a crucial role, through stimulation of AT1 receptors, in the production and progression of stress-induced gastric injury, and AT1 receptor antagonists could be of therapeutic benefit.