OP0046 TARGETING IRAK1 AND 4 SIGNALING WITH R835, A NOVEL ORAL SMALL MOLECULE INHIBITOR: A POTENTIAL NEW TREATMENT FOR SYSTEMIC LUPUS ERYTHEMATOSUS

Background:

Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by loss of immunological tolerance, hyperactivation of immune cells, proinflammatory cytokine production and, ultimately, end organ damage due to immune complex deposition. Toll-like receptors (TLRs), which are essential to the innate immune response to microbes and other danger signals, play a key role in the pathogenesis of SLE by recognition of self-molecules (1). Interleukin receptor associated kinases (IRAK)1 and 4 are responsible for initiating MyD88-dependent signaling from most TLRs and Interleukin-1 Receptors (IL-1R) and represent attractive targets for the therapeutic treatment of SLE (2). We have identified a potent and selective IRAK1/4 inhibitor, R835, that substantially suppressed the elevation of LPS (TLR4 agonist)-induced serum cytokines in healthy human volunteers in a recently completed phase 1 study.

Objectives:

The aim of our study was to investigate the effect of IRAK1/4 selective inhibition as potential therapeutic approach for SLE. We evaluated the effect of our clinical candidate R835 on TLR7 signaling and in a mouse model of lupus-like disease.

Methods:

Human primary dendritic cells and whole blood were stimulated with gardiquimod (TLR7 agonist) to evaluate the effect of R835 on Interferon-alpha (IFN-α) production. R835 was further evaluated for its efficacy on survival and disease progression in lupus-prone NZB/W F1 mice with early or active signs of disease.

Results:

R835 inhibited TLR7-induced cytokine production in human dendritic cells and whole blood. Given orally to mice, R835 dose-dependently decreased serum IFN-α in response to administration of a TLR7 agonist. Furthermore, treatment of NZB/W F1 lupus-prone mice with R835 reversed the progression of lupus-like disease and the establishment of a pro-inflammatory environment, as demonstrated by decreased levels of proteinuria, blood urea nitrogen and autoantibodies, and reversal of renal pathology.

Conclusion:

To our knowledge, R835 is the first dual IRAK1/4 inhibitor to enter clinical development and provides an attractive approach to treat a range of autoimmune and rheumatic diseases, including lupus.

References:

[1]Signals via the Adaptor MyD88 in B cells and DCs Make Distinct and Synergistic Contributions to Immune Activation and Tissue Damage in Lupus. Lino L. Teichmann, Dominik Schenten, Ruslan Medzhitov, Michael Kashgarian, and Mark J. Shlomchik. Immunity. 2013 March 21; 38(3): 528–540.

[2]Suppression of IRAK1 or IRAK4 Catalytic Activity, but Not Type 1 IFN Signaling, Prevents Lupus Nephritis in Mice Expressing a Ubiquitin Binding-Defective Mutant of ABIN1. Nanda SK, Lopez-Pelaez M, Arthur JS, Marchesi F, Cohen P. J Immunol. 2016 Dec 1;197(11):4266-4273.

Disclosure of Interests:

Chrystelle Lamagna Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Meagan Chan Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Art Bagos Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Ernest Tai Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Chi Young Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Yan Chen Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Lu Chou Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Gary Park Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Esteban Masuda Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Vanessa Taylor Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals

AB0058 CELL-TYPE SPECIFIC REGULATION OF IL-1R SIGNALING BY R835, A DUAL IRAK1/4 INHIBITOR

Background:

Interleukin-1 beta (IL-1b) is a key mediator of the inflammatory response and is known to exacerbate damage during chronic disease and acute tissue injury. Through association with the adaptor protein Myd88, interleukin receptor associated kinases (IRAK)1 and 4 initiate signaling downstream of IL-1Rs resulting in the activation of the NFkB and MAPK pathways and the production of proinflammatory cytokines (1). IL-1Rs are broadly expressed across cell types and little is known about differences in signaling between cell types and the role of IRAK1 and IRAK4 kinase activity.

Objectives:

We have identified a potent and selective IRAK1/4 inhibitor, R835, that substantially suppressed the elevation of LPS (TLR4 agonist)-induced serum cytokines in healthy human volunteers in a recent phase 1 study. The aim of this study was to evaluate the effect of R835 on IL-1R signaling in primary human fibroblasts and endothelial cells.

Methods:

Human dermal fibroblasts, lung fibroblasts or endothelial cells were stimulated with IL-1b and the effect of R835 on the signaling pathway was evaluated by western blotting. Human dermal fibroblasts were stimulated with different amounts of IL-1b to evaluate both the signaling pathways activated and the cytokines produced. The ability of R835 to inhibit cytokine production induced by high or low amounts of IL-1b in dermal fibroblasts was assessed.

Results:

In human endothelial cells, inhibition of IRAK1/4 kinases with R835 resulted in a block of IL-1b-induced IRAK4 phosphorylation, IRAK1 degradation and downstream NFkB, p38 and JNK activation. In contrast, in both human primary dermal and lung fibroblasts stimulated with IL-1b, we observed potent inhibition of IRAK4 phosphorylation, IRAK1 degradation, and downstream JNK phosphorylation, but no inhibition of NFkB pathway proteins and only weak inhibition of p38. Upon titration of IL-1b we observed that dermal fibroblasts produced IL-8 and GRO in response to low levels of IL-1b (20pg/ml), and produced additional cytokines including G-CSF and GM-CSF with higher levels of IL-1b (400pg/ml). In the presence of low levels of IL-1b (20pg/ml), we observed a weak activation of NFkB pathway proteins and p38, compared to a very robust NFkB, p38 and additional JNK activation in the presence of higher levels of IL-1b (400pg/ml). Consistent with these results, in dermal fibroblasts, R835 showed little to no inhibition of IL-8 and GRO induced by low levels of IL-1b, but potently inhibited G-CSF and GM-CSF induced by high levels of IL-1b where JNK was activated.

Conclusion:

This study has elucidated signaling differences between cell types downstream of the IL-1R. In endothelial cells, as in myeloid cells, the kinase activity of IRAK1 and IRAK4 is required for the activation of all downstream signaling. Unexpectedly, in human fibroblasts, IRAK1/4 kinase activity appears to primarily regulate the JNK pathway, and not the NFkB pathway. Concomitant with that, only the cytokines induced by the additional activation of JNK in fibroblasts are regulated by a dual IRAK1/4 inhibitor. Clinically, an IRAK1/4 inhibitor may show select inhibition of IL-1b-induced cytokines depending on the tissue and cell type involved in inflammation.

References:

[1]Flannery S, Bowie A G. The interleukin-1 receptor-associated kinases: Critical regulators of innate immune signaling. Biochemical Pharmacology, Volume 80, Issue 12, 15 December 2010, Pages 1981-1991.

Disclosure of Interests:

Sylvia Braselmann Shareholder of: Shareholder of Rigel Pharmaceuticals, Employee of: Employee of Rigel Pharmaceuticals, Ernest Tai Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Roy Frances Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Chi Young Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Vadim Markovtsov Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Esteban Masuda Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Vanessa Taylor Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals

OP0133 PRECLINICAL EFFICACY OF R835, A NOVEL IRAK1/4 DUAL INHIBITOR, IN RODENT MODELS OF JOINT INFLAMMATION

Background:

Interleukin receptor associated kinases (IRAK) 1 and 4 are kinases involved in Toll-Like Receptor (TLR) and Interleukin-1 Receptor (IL-1R) signaling pathways, which regulate innate immunity and inflammation. Dysregulation of IRAK1/4 signaling can lead to a variety of inflammatory conditions including rheumatoid and gouty arthritis. As a result, IRAK1/4 are promising therapeutic targets for rheumatic diseases (1). We have identified a potent and selective IRAK1/4 inhibitor, R835, that substantially suppressed the elevation of LPS (TLR4 agonist)-induced serum cytokines in healthy human volunteers in a recently completed phase 1 study.

Objectives:

The aim of our study was to investigate the effect of IRAK1/4 selective inhibition as a potential therapeutic approach for rheumatological diseases. We evaluated the inhibition by our clinical candidate, R835, on TLR-, IL-1R- and NLRP3 inflammasome-induced cytokine production, as well as in preclinical models of arthritis.

Methods:

The effect of R835 on TLR- or IL-1R-induced cytokine production was evaluated in vitro using THP-1, human primary endothelial cells and human primary dendritic cells. The activity of R835 on the NLRP3 inflammasome was also tested in vitro using THP-1 cells. The pharmacokinetic-pharmacodynamic relationship of R835 was evaluated in a mouse model of IL-1b-induced cytokine release. Mice were pre-treated orally with vehicle or R835 prior to challenge; serum cytokine and plasma compound levels were determined. The efficacy of IRAK1/4 inhibition by R835 in rodent models of joint inflammation was evaluated in a mouse model monosodium (MSU)-induced peritonitis, in rat model of MSU-induced gouty arthritis and in a rat model of collagen-induced arthritis (CIA).

Results:

In human cells, R835 blocked proinflammatory cytokine production in response to TLR, IL-1R and NLRP3 inflammasome activation. In mice, R835 dose-dependently decreased serum cytokines in response to administration of IL-1b. Mice pre-treated with R835 demonstrated dose-dependent reductions in MSU crystal-induced serum and peritoneal cytokine levels, as well as neutrophil influx in the peritoneal cavity. Prophylactic and therapeutic treatment with R835 also resulted in significant inhibition of MSU crystal-induced knee edema and pain in a rat model of human gouty arthritis. In the rat model of CIA, R835 blocked both onset and progression of disease, by reducing inflammation, cartilage degeneration and synovial inflammation.

Conclusion:

R835 is a promising clinical candidate for the treatment of a range of cytokine-driven rheumatological diseases. R835 has proven to have desirable pharmacokinetic properties, was well tolerated and suppressed LPS-induced serum cytokines in healthy volunteers in a recent phase 1 study.

References:

[1]Bahia M S, Kaur M, Silakari P, Silakari O. Interleukin-1 receptor associated kinase inhibitors: Potential therapeutic agents for inflammatory- and immune-related disorders. Cellular Signalling 27 (2015) 1039–1055.

Disclosure of Interests:

Chrystelle Lamagna Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Meagan Chan Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Ernest Tai Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Stacey Siu Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Roy Frances Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Sothy Yi Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Chi Young Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Vadim Markovtsov Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Yan Chen Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Lu Chou Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Gary Park Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Esteban Masuda Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals, Vanessa Taylor Shareholder of: Rigel Pharmaceuticals, Employee of: Rigel Pharmaceuticals

Phenotypic differences between electrocardiographic and echocardiographic determination of hypertrophic cardiomyopathy in genetically affected subjects

OBJECTIVES

In the molecular era, two types of phenotypic differences are recognized between electrocardiography (ECG) and echocardiography in hypertrophic cardiomyopathy (HCM); ECG abnormalities in carriers without left ventricular hypertrophy (LVH), and normal ECG patterns in carriers with LVH. The goal of this study was to evaluate the diagnostic value of ECG for detecting carriers without LVH, and also to assess normal ECG patterns in carriers with LVH from the genetic standpoint of HCM.

SETTING

A matched case-control study in a university hospital and general hospitals in Japan.

PATIENTS AND DESIGN

ECG and echocardiographic findings were analysed in 173 genotyped subjects (107 genetically affected, 66 unaffected) from families with disease-causing mutations in four genes.

RESULTS

ECG abnormalities were found in 18 (54.5%) of 33 nonhypertrophic carriers, but only nine (13.6%) of 66 noncarriers (P < 0.001). For detecting nonhypertrophic carriers, ST-T abnormalities showed the highest accuracy amongst the three major ECG criteria. In contrast, normal ECG patterns were found in eight (10.8%) of 74 carriers with LVH. The sensitivity of ECG for detecting carriers with LVH in families with the cardiac myosin-binding protein C, cardiac troponin T and cardiac troponin I gene mutations was 83%, 88% and 94% respectively.

CONCLUSION

These findings suggest that ECG may have favourable diagnostic value even for detecting nonhypertrophic carriers. Furthermore, diagnostic value of ECG may differ according to the genes involved. Our data may contribute to interpretation of phenotypic differences between ECG and echocardiography from the viewpoint of molecular genetics of HCM.

Clinical study of urine NMP 22 (nuclear matrix protein 22) as a tumor marker in urinary epithelial cancer

The prognosis of urinary epithelial cancer is still poor, and early detection of this cancer is strongly desirable. The sensitivity of conventional urinary cytology is not satisfactory enough. It is hoped that a specific tumor marker will be established. In recent years, it has been reported that urine NMP 22 is very useful and that urine BFP is also relatively useful. We have now determined urine NMP22 and BFP and studied their clinical usefulness as a tumor marker. Using patients diagnosed with histologically confirmed urinary epithelial cancer as the subjects, we retrospectively studied the usefulness of NMP 22, BFP and cytology mainly with regard to the sensitivity (positivity rate), and also in relation to atypia, degree of infiltration and clinical course.

Retroviral delivery of peptide modulators of cellular functions

Stable transduction of genetic material, in combination with sensitive methodologies for in vivo study of cell physiology, provides an opportunity to efficiently evaluate the functions of regulatory proteins. To dissect the minimal therapeutic function of such proteins, we have stably expressed protein microdomains as fusions, composed of short peptides, and detected specific subfunctions distinct from holoprotein function, using flow cytometry and other techniques. We demonstrate that retroviral delivery of the 24-amino-acid proliferating cell nuclear antigen-binding motif (p21C), derived from the C-terminus of the cell cycle inhibitor protein, p21, is sufficient to induce cell cycle arrest. Cells expressing this peptide motif reversibly execute both G1- and G2-checkpoint controls that are normally activated subsequent to interference with DNA synthesis. The p21C effect is distinct from results obtained with an intact p21 protein that also binds cyclin-CDK complexes and arrested cells exclusively at the G1/S transition. Thus, microdomains can exert unique biological effects compared to the parental molecules from which they were derived. To further evaluate the peptide delivery strategy, we analyzed the role of various kinases in IgE-mediated stimulation of mast cell exocytosis. Primary bone marrow-derived mast cells were transduced with retroviral constructs encoding short-kinase inhibitor motifs and analyzed by flow cytometry for effects on exocytosis. We found that a specific protein kinase A (PKA) inhibitor peptide suppressed IgE-mediated stimulation of mast cell exocytosis. This anti-exocytotic effect was mimicked by a small molecule inhibitor of PKA (KT5720). Thus, the ability to express protein microdomains can be a powerful means to subtly perturb cellular physiology in manners that reveal new paths for therapeutic intervention. We believe that such approaches might allow for new forms of gene therapy to become available.

Quantitative measurement of mast cell degranulation using a novel flow cytometric annexin-V binding assay

BACKGROUND

Mast cells are primary mediators of allergic inflammation. Antigen-mediated crosslinking of their cell surface immunoglobulin E (IgE) receptors results in degranulation and the release of proinflammatory mediators including histamine, tumor necrosis factor-alpha, and leukotrienes.

METHODS

Mast cells were stimulated to degranulate by using either IgE crosslinking or ionophore treatment. Exogenously added annexin-V was used to stain exocytosing granules, and the extent of binding was measured flow cytometrically. Release of the enzyme beta-hexosaminidase was used for population-based measurements of degranulation. Two known inhibitors of degranulation, the phosphatidylinositol 3 kinase inhibitor wortmannin and overexpression of a mutant rab3d protein, were used as controls to validate the annexin-V binding assay.

RESULTS

Annexin-V specifically bound to mast cell granules exposed after stimulation in proportion to the extent of degranulation. Annexin-V binding was calcium dependent and was blocked by phosphatidylserine containing liposomes, consistent with specific binding to this membrane lipid. Visualization of annexin-V staining showed granular cell surface patches that colocalized with the exocytic granule marker VAMP-green fluorescent protein (GFP). Wortmannin inhibited both annexin-V binding and beta-hexosaminidase release in RBL-2H3 cells, as did the expression of a dominant negative rab3d mutant protein.

CONCLUSIONS

The annexin-V binding assay represents a powerful new flow cytometric method to monitor mast cell degranulation for functional analysis.

Late recurrence of acinic cell carcinoma of the parotid gland

Acinic cell carcinoma of the salivary glands is a rare cancer representing a low grade malignancy. The recurrence of a tumor is sometimes encountered, usually within 5 years of initial operation. We describe an unusual recurrence after a long interval following primary surgery. In 1987, a 60-year-old woman underwent excision of a mass in the superficial lobe of the right parotid gland under the preoperative diagnosis of a benign tumor. A histologic diagnosis of acinic cell carcinoma was made by examining sections from the resected mass. The patient noted several small nodules in the right parotid region in 1995, but she did not visit our clinic until 1998 when tenderness developed. A locally recurrent tumor and cervical lymph nodes containing metastases were resected and postoperative radiotherapy was given 11 years after the first operation. At least 10 years of follow-up may be necessary for patients with acinic cell carcinoma because of slow-tumor growth.

ret/PTC expression may be associated with local invasion of thyroid papillary carcinoma

BACKGROUND AND OBJECTIVES

The exact role of ret/PTC in the development of papillary carcinoma remains unclear. Expression of the ret/PTC oncogene was examined immunohistochemically to address its role in the progression of thyroid carcinomas.

METHODS

Paraffin-embedded samples from 34 clinically evident thyroid papillary carcinomas and 19 occult papillary carcinomas were analyzed using an antibody raised against the ret tyrosine kinase domain.

RESULTS

Expression of ret/PTC was demonstrated in 6/19 (32%) occult carcinomas. The frequency of expression of ret/PTC in clinically evident carcinomas in 16/34 (47%) was significantly higher than in normal tissues (0%) and follicular adenomas (1/14, 7%, P < 0.01).ret/PTC expression was observed more frequently in the peripheral areas of clinically evident carcinomas (P < 0.01). Although there was no correlation of ret/PTC expression with tumor size, lymph node metastasis, or distant metastasis, the incidence of ret/PTC expression in tumors with extrathyroidal invasion (13/19, 68%) was significantly higher than those without extrathyroidal invasion (3/15, 20%, P < 0.01). Local invasion was found in none of the occult carcinomas. The frequency of expression in occult carcinomas was significantly lower than in clinically evident carcinomas with extrathyroidal invasion (P < 0.05).

CONCLUSIONS

The ret/PTC oncogene may be involved in the local invasion of thyroid papillary carcinomas.

[Mucosal microcirculation and angiogenesis in gastrointestinal tract]

In this review, various aspects of gastrointestinal microcirculation were described. Endothelin-1, vasoconstrictor, is elevated in gastric mucosa, causes gastric ischemia and results in gastric ulceration in human and animals under physical stress. Vasodilators such as NO anticipate the alove actions of endothelin, and thereby protect mucosa from injury. Once ulcer is developed, angiogenesis plays a key role in its healing. Various growth factors, cyclooxygenases-1 and -2, and non-peptide angiogenic factors stimulate this phenomenon and participate in ulcer healing. However, acidic conditions, H. pylori and its product, ammonia, suppress angiogenesis in vitro and in vivo. These evidences may explain why ulcer heals so slowly in gastroduodenal mucosa.

Flow cytometric analysis of cell proliferation kinetics during duodenal ulcer healing

Cell proliferation in the gastroduodenal mucosa of patients with duodenal ulcers was evaluated using flow cytometry. Forty patients with duodenal ulcers and 12 normal subjects were investigated. Biopsy samples were obtained during endoscopic examination and subjected to DNA analysis by flow cytometry. Thirty patients with duodenal ulcers were healed within 3 months with H2 blockers (tractable or responsive ulcers), whereas 10 patients did not respond to treatment (intractable ulcers). The percentage of cells at the DNA-synthetic phase, an index of cell proliferation, was constant in the adjacent duodenal mucosa 2 cm from ulcer margin and antral mucosa during duodenal ulcer healing. The index at the margin of tractable ulcers was elevated during the active stage (12.9 +/- 1.3), peaked during the healing stage (15.4 +/- 2.8) and returned to the same level at the scarring stage (10.9 +/- 2.0) as normal controls (10.3 +/- 1.7). However, the index was not elevated in intractable ulcers (10.3 +/- 1.7 in the healing stage) and was smaller than in tractable ulcers. These data indicate that augmented mucosal cell proliferation at the ulcer margin plays an important role in duodenal ulcer healing and intractable ulcers are characterized by an abnormal failure to accelerate DNA synthesis to achieve ulcer repair.

Changes in cellular composition induced by neocarzinostatin pretreatment in Meth A-bearing mice and the responsible antitumor effector cells

We previously reported that tumor eradication was induced by a single injection of neocarzinostatin (NCS) between 1 day and 4 weeks before Meth A transplantation in Balb/c mice via augmenting host-mediated antitumor activity. In order to elucidate the mechanism of this tumor eradication, the cellular components of spleen and regional lymph nodes, tumor infiltrating cells and antitumor effector cells were investigated. Pretreatment with NCS on day -3 caused an increase in the percentage of T-cell subsets, a decrease in the percentage of B-cells, Mac-1+ cells and asialo GM1+ cells and a decrease of the total cell number in the spleen. These changes were observed before but not during the period of tumor regression and were also observed in non-transplanted mice with NCS treatment. In the lymph nodes, while B-cells increased on Meth A transplantation, this was suppressed by NCS pretreatment. Although histological examination of tumor nodules showed the presence of only a few host immune cells in the tumor tissue, the area of necrosis was already extensive on day 7 and expanded thereafter. In vivo depletion of whole T-cells, T-cell subsets or asialo GM1+ cells by antibody treatment suggests that the antitumor effector cells in tumor eradication were Thy1,2+/Lyt2+, and at least some of which also express asialo GM1 antigen and that L3T4+ T-cells were also involved in tumor eradication.

Estimation of free calcium levels after thyroidectomy

Total calcium is routinely measured after thyroidectomy in a clinical setting, while the measurement or calculation of the free calcium level is not generally performed. We reviewed total and free calcium levels in patients who underwent lobectomy (n = 15), subtotal thyroidectomy (n = 15) and total thyroidectomy (n = 15). Postoperative total calcium levels decreased significantly in comparison to preoperative levels in all thyroidectomies (p < 0.01), and this fall was significantly related to the extent of surgery (p < 0.01). In contrast, there was no significant difference between preoperative and postoperative free calcium levels in patients undergoing lobectomy, although we found a decrease in free calcium levels after both subtotal and total thyroidectomy. Total protein levels decreased regardless of the type of operation. Serum total calcium levels were thought to be altered by serum protein levels through the change of protein-bound calcium levels. When examined for free calcium levels, some patients were administered unnecessary calcium supplementation because hypocalcemia had been judged from the total calcium level. Since the wrong diagnosis may be given with regard to hypoparathyroidism by measurement of total calcium levels alone, we propose that free calcium levels should be routinely measured or calculated after thyroidectomy.

Endothelin-1 in the gastric mucosa in stress ulcers of critically ill patients

OBJECTIVE

Gastric microcirculatory disturbances are involved in the pathogenesis of stress ulcers; however, vasomodulators causing this process are not fully understood. This study was conducted to investigate the role of endothelin 1 (ET-1), a potent vasoconstrictive peptide, in stress ulcers in critically ill patients.

METHODS

Using sandwich enzyme immunoassay, we measured ET-1 content in plasma and the gastric mucosa of 16 critically ill patients with traumatic head injury on admission and of 11 healthy subjects. Gastric mucosal samples were obtained endoscopically. When gastric drainage contained occult blood, endoscopic examination was performed again, and ET-1 concentrations in injured and adjacent normal mucosa were compared.

RESULTS

Plasma and mucosal ET-1 concentrations were significantly higher in critically ill patients on admission (6.1 +/- 0.6 pg/ml and 13.8 +/- 1.6 ng/g, respectively) compared with values in control subjects (2.7 +/- 0.4 pg/ml and 8.2 +/- 0.5 ng/g, respectively) (p < 0.01). The mucosal ET-1 concentration tended to be elevated in patients who had experienced hypoxia compared with those who had not (p = 0.07). In five patients who were again examined endoscopically, the ET-1 concentration in the injured mucosa was significantly higher than that in adjacent mucosa (19.2 +/- 3.2 and 10.1 +/- 1.6 ng/g, respectively; p < 0.05).

CONCLUSIONS

These results suggest that endogenous ET-1 plays an important role in the local pathogenesis of stress ulcers, especially those caused by hypoxia.

Plasma and gastric mucosal endothelin-1 concentrations in patients with peptic ulcer

Peptic ulcer in the human stomach causes localized destruction of the gastric wall, which may be associated with focal vascular insufficiency. Endothelin-1, an extremely potent vasoconstrictor peptide, modulates regional blood flow in the vasculature of stomach, suggesting a role for endothelin-1 in peptic ulcer. We examined the relationship among endogenous plasma and mucosal endothelin-1 concentrations and the severity and area of ulcer in 19 patients with gastric ulcers and eight healthy adults. Endothelin-1 concentrations were measured by enzyme immunoassay in plasma and gastric mucosal specimens from ulcer margins, corpus, and antrum. The severity and area of ulcer were assessed endoscopically. Plasma endothelin-1 concentrations in active (P < 0.01 compared with normal) and healing (P < 0.05) stages of ulcer were significantly greater than those in normal subjects. Plasma endothelin-1 concentrations, but not mucosal endothelin-1 concentrations in the ulcer margin, were significantly associated with the severity of the ulcer. There was a significant positive correlation between plasma endothelin-1 concentrations and area of ulcer (r = 0.70, P < 0.01). In conclusion, locally increased endothelin-1 may be an important mediator contributing to the pathogenesis of peptic ulcer.

Plasma and gastric mucosal endothelin-1 concentrations in patients with peptic ulcer

Peptic ulcer in the human stomach causes localized destruction of the gastric wall, which may be associated with focal vascular insufficiency. Endothelin-1, an extremely potent vasoconstrictor peptide, modulates regional blood flow in the vasculature of stomach, suggesting a role for endothelin-1 in peptic ulcer. We examined the relationship among endogenous plasma and mucosal endothelin-1 concentrations and the severity and area of ulcer in 19 patients with gastric ulcers and eight healthy adults. Endothelin-1 concentrations were measured by enzyme immunoassay in plasma and gastric mucosal specimens from ulcer margins, corpus, and antrum. The severity and area of ulcer were assessed endoscopically. Plasma endothelin-1 concentrations in active (P < 0.01 compared with normal) and healing (P < 0.05) stages of ulcer were significantly greater than those in normal subjects. Plasma endothelin-1 concentrations, but not mucosal endothelin-1 concentrations in the ulcer margin, were significantly associated with the severity of the ulcer. There was a significant positive correlation between plasma endothelin-1 concentrations and area of ulcer (r = 0.70, P < 0.01). In conclusion, locally increased endothelin-1 may be an important mediator contributing to the pathogenesis of peptic ulcer.

Relationship between prognostic score and thyrotropin receptor (TSH-R) in papillary thyroid carcinoma: immunohistochemical detection of TSH-R

We have demonstrated the expression of thyrotropin receptor (TSH-R) in thyroid neoplasms (13 adenomas, 21 papillary carcinomas, two follicular carcinomas) and adjacent normal thyroid using the monoclonal antibody against human TSH-R and have also demonstrated a relationship between prognostic scores and the expression of TSH-R. Among the adenomas, eight showed an intensity similar to that of normal thyroid and five showed a higher intensity than normal. Two tumours exhibited heterogeneous distribution of TSH-R. Among the papillary carcinomas, seven showed similar intensity to normal tissue and four showed higher intensity and ten showed weaker intensity. Eight tumours showed heterogeneous distribution of the stain. Among the follicular carcinomas, one showed similar intensity to normal tissue and the other exhibited weaker intensity. Both cases showed homogeneous distribution of TSH-R. The adenomas never showed a weaker intensity than normal thyroid, but various intensities of TSH-R occurred in differentiated carcinomas. There was no significant relationship between the clinical data and the signal intensity in the adenomas. Among the papillary carcinomas, however, the group with weaker intensity had significantly poorer prognostic scores than the other two groups. Thus, we assume that low TSH-R may be expressed by the clinically high-risk group of patients with papillary thyroid carcinoma.

Induction of antinuclear antibody after interferon therapy in patients with type-C chronic hepatitis: its relation to the efficacy of therapy

BACKGROUND

The prevalence of antinuclear antibody (ANA) and interferon (IFN)-induced ANA has been documented in patients with chronic hepatitis C. In the present study we evaluated whether the induction pattern of ANA after IFN therapy is related to the efficacy of IFN therapy.

METHODS

Forty-four patients with chronic hepatitis C were enrolled. Autoimmune hepatitis was excluded in all. ANA was measured every month before, during, and for 6 months after IFN therapy (total dose, 336-480 M units).

RESULTS

Eight of the 44 (18%) patients were positive for ANA before IFN therapy (group I). In group I six of the eight ANA-positive patients showed an increase in ANA titers during the therapy. Twenty-two of 36 (61%) ANA-negative patients turned positive for ANA, with titers of 1:80 or less during IFN therapy (group II). In 14 of the 36 (39%) ANA-negative patients ANA remained negative throughout the therapy (group III). The rates of sustained responders with a negativity of serum hepatitis C virus RNA and with normal alanine aminotransferase levels for at least 6 months after the cessation of therapy in groups I, II, and III were 25%, 23%, and 21%, respectively, giving no significant difference in the efficacy of therapy. No serious side effect was observed during the therapy.

CONCLUSIONS

Administration of IFN frequently produced an induction of ANA or an increase in its titer, which did not affect the efficacy of IFN therapy.

Changes in cellular components of spleen and lymph node cells and the effector cells responsible for Meth A tumor eradication induced by zinostatin stimalamer

We reported previously that pretreatment with zinostatin stimalamer (ZSS) eradicated Meth A tumors in BALB/c mice. We herein investigated cellular components of spleen and lymph node cells of Meth A-bearing ZSS-pretreated mice by flow cytometry; the antitumor effector cells by in vivo depletion of T cells, NK cells, or macrophages; and host-mediated antitumor activity associated with ZSS treatment after tumor transplantation. ZSS given on day-3 transiently decreased the number of spleen cells. The percentage of T cells increased, but B cells and macrophages decreased. B cells decreased in inguinal lymph nodes in Meth A-bearing ZSS-pretreated mice, but increased in Meth A-bearing control mice. In vivo depletion experiments using antibodies or carrageenan showed that antitumor effector cells for tumor eradication are Thy1.2+/Lyt2.2+ and that at least a part of them are asialo GM1+. Thy1.2+/Lyt2.2+/asialoGM1- cells are important in generation of the antitumor activity of ZSS; however, L3T4+ T cells are also involved in initiation of tumor eradication. The result of ZSS treatment after tumor transplantation suggests that ZSS might exhibit antitumor activity by augementating host-mediated antitumor resistance, as well as its intrinsic cytocidal activity.

Antitumor resistance induced by zinostatin stimalamer (ZSS), a polymer-conjugated neocarzinostatin (NCS) derivative. I. Meth A tumor eradication and tumor-neutralizing activity in mice pretreated with ZSS or NCS

Zinostatin stimalamer (ZSS) is a new anticancer agent derived from neocarzinostatin (NCS), which is synthesized by conjugation of one molecule of NCS and two molecules of poly(styrene-co-maleic acid). ZSS exhibited potent in vitro and in vivo antitumor activity in preclinical experiments, and a clinical trial of the intra-arterial administration of ZSS with iodized oil on hepatocellular carcinoma showed potent antitumor activity. We investigated the effect of ZSS and NCS on antitumor resistance and found that pretreatment with either drug suppressed the growth of MethA tumors in Balb/c mice and induced tumor eradication when given separately by single administration at therapeutic doses between 1 day and 4 weeks before tumor transplantation. The findings that the cytocidal activity of these drugs was not detected in vivo at the time of tumor transplantation and that tumor regression was preceded by a period of transient growth suggested that tumor regression was due to host-mediated antitumor activity induced by these drugs. Pretreatment with ZSS or NCS also suppressed the growth of Colon 26 carcinoma and Sarcoma 180. The finding that NCS showed the same effect as ZSS suggests that poly(styrene-comaleic acid) is not essential for the induction of host-mediated antitumor activity. Furthermore, apo-ZSS, which lacks cytocidal activity, did not induce antitumor activity. From this, it is suggested that the cytocidal effect of ZSS involves the induction of host-mediated antitumor resistance. In athymic Balb/c nu/nu mice, pretreatment with ZSS or NCS did not induce tumor eradication, suggesting that mature T lymphocytes play an important role in tumor eradication. Challenging MethA was rejected without transient growth in mice that had been cured of MethA, but challenging Colon 26 was not, showing that anti-MethA resistance was augmented selectively in the MethA-eradicated mice. Splenocytes from MethA-bearing mice pretreated with the drug showed tumor-neutralizing activity beginning 14 days after tumor transplantation. Tumor-neutralizing activity was only induced after MethA transplantation. The effector cells of this tumor-neutralizing activity were Thy1.2+ T lymphocytes that had been passed through a nylon-wool column, but no significant augmentation of cell-mediated cytotoxic activity of splenocytes from MethA-eradicated mice was observed in vitro.

Endogenous nitric oxide modulates ethanol-induced gastric mucosal injury in rats

BACKGROUND/AIMS

Endothelium-derived relaxing factor regulates vascular tone via vasodilation. The relative contribution of endogenous nitric oxide to the pathophysiology of ethanol-induced gastric mucosal microcirculatory disturbances was investigated in anesthetized rats.

METHODS

Macroscopic and microscopic gastric mucosal damage and gastric mucosal hemodynamics including blood flow and hemoglobin oxygen saturation (ISO2) were assessed by pretreatment with a specific NO synthase inhibitor, N omega-nitro-L-arginine (L-NNA), before and after intragastric administration of ethanol.

RESULTS

Pretreatment with L-NNA significantly increased macroscopic (7.7-fold) and microscopic damage caused by 30% ethanol. Concurrent administration of L-arginine, but not D-arginine, significantly reduced the increase in mucosal damage. Similar results were obtained with 60% ethanol. Pretreatment with L-NNA decreased both mucosal blood flow and ISO2 in the basal period and enhanced decreases in both mucosal blood flow (2.7-fold) and ISO2 (4.3-fold) induced by 30% ethanol compared with controls. Concurrent administration of L-arginine, but not D-arginine, significantly inhibited the effect of L-NNA on blood flow and ISO2 in the basal period as well as after intragastric administration of 30% ethanol.

CONCLUSIONS

Endogenous NO modulates ethanol-induced gastric mucosal injury through the regulation of gastric mucosal microcirculation.

Does intravenous glutamine prevent bacterial translocation in hemorrhagic shock?

Bacterial translocation across the gut wall may be associated with insult to the latter. In this situation, intestinal flora can enter the blood stream and lymph nodes and be transported to other organs. Glutamine is a nonessential amino acid not presently included in total parenteral nutrition (TPN) preparations. The use of glutamine-enriched TPN in the rat has resulted in a significant reduction in bacterial translocation. This study attempted to evaluate the role of glutamine in preventing bacterial translocation following hemorrhagic shock in a rat model. Forty Sprague-Dawley rats were equally divided into two groups. The controls were given TPN solution, while the treated group had glutamine instead of the standard alanine present in TPN. Hemorrhagic shock was induced in both groups and blood cultures were performed. Glutamine-treated rats did not show a significant difference in survival suggesting that it is of no particular value in severe hemorrhagic shock in rats.

Endogenous nitric oxide attenuates ethanol-induced perturbation of hepatic circulation in the isolated perfused rat liver

The purpose of this study was to clarify the role of endogenous nitric oxide in ethanol-induced perturbation of microcirculation and hepatic injury in perfused rat liver. Infusion of ethanol into the portal vein at 25 and 100 mmol/L increased portal pressure, which is an indicator of hepatic vasoconstriction, in a concentration-dependent fashion. Portal pressure started to rise immediately after ethanol load, then decreased gradually and remained at higher than basal levels throughout the period of ethanol infusion. Release of lactate dehydrogenase into the effluent perfusate began to increase after 30 min of ethanol infusion and continued to increase during the 60-min period of ethanol infusion. The lactate dehydrogenase level in the effluent perfusate at 60 min was dependent on the ethanol concentration (0 mmol/L, 8 +/- 3 IU/L; 25 mmol/L, 16 +/- 2 IU/L; 100 mmol/L, 52 +/- 6 IU/L). Simultaneous infusion of NG-monomethyl-L-arginine, a nitric oxide synthesis inhibitor, enhanced significantly the ethanol-induced increase in portal pressure by 100% to 400% and increased lactate dehydrogenase release by 40% to 80%. The effect of NG-monomethyl-L-arginine on the ethanol-induced increase in portal pressure was completely reversed by the co-infusion of an excess dose of L-arginine. Change in portal pressure averaged over 60 min of ethanol infusion correlated with levels of lactate dehydrogenase release 60 min after the initiation of ethanol infusion (r = 0.77, p < 0.01). In conclusion, inhibition of the action of endogenous nitric oxide was associated with an increase in hepatic vasoconstriction and hepatocellular damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased expression of c-met messenger RNA following acute gastric injury in rats

The aim of the present study was to evaluate messenger RNA expression of c-met, a hepatocyte growth factor receptor gene, after gastric mucosal injury in rats. Male Sprague-Dawley rats were fasted for 24 hours, received 0.6 N hydrochloric acid (HCl), and served for polyadenylated RNA extraction from the oxyntic gastric mucosa. The transcripts of rat c-met gene were analyzed by reverse-transcript polymerase chain reaction and Northern blotting. Although it was detected even before the HCl administration, the c-met expression increased 6, 24 and 48 hours after the HCl administration. Thereafter, gastric mucosal injury diminished and the c-met expression declined. Hepatocyte growth factor reportedly plays an important role in gastric cell proliferation. The increased c-met expression indicates that this gene may participate in the healing process of gastric mucosa after injury.

Role of endothelin 1 in hemorrhagic shock-induced gastric mucosal injury in rats

BACKGROUND/AIMS

Gastric microcirculatory disturbances are involved in the pathogenesis of stress ulcers; however, vasomodulators regulating this process are not fully understood. This study was conducted to investigate the role of endothelin 1 (ET-1) in hemorrhagic shock-induced gastric mucosal damage in rats.

METHODS

ET-1 contents in plasma and gastric mucosa were measured and gastric mucosal damage was evaluated during a control period, 60 minutes of ischemia, 15 minutes of reperfusion, and 30 minutes of postreperfusion. Next, effects of BQ-123, an endothelinA receptor antagonist, on the gastric mucosal damage and hemodynamics were studied.

RESULTS

Both plasma and mucosal ET-1 significantly increased after ischemia and reperfusion compared with the control values, but only mucosal ET-1 continued to increase after reperfusion, leading to the development of gastric mucosal damage. BQ-123, administered just before reperfusion, reduced mucosal damage in the postreperfusion period dose-dependently and improved mean gastric mucosal blood flow and mucosal hemoglobin oxygen saturation during the 30-minute postreperfusion period.

CONCLUSIONS

These results suggest that endogenous ET-1 plays an important role in the pathogenesis of hemorrhage shock-induced gastric mucosal damage through impairment of mucosal microcirculation. Further, endothelinA antagonists may have therapeutic benefits for shock-induced gastric mucosal damage.

Endothelin-1 is involved in the pathogenesis of ischemia/reperfusion liver injury by hepatic microcirculatory disturbances

Hepatic microcirculatory perturbation is observed after ischemia/reperfusion. Endothelin-1, a potent vasoconstrictive peptide, is known to modulate local circulation. This study was designed to examine whether endothelin-1 participates in the mechanism of microcirculatory disturbance and damage of the liver after ischemia/reperfusion. Ischemia in the median and left lateral lobes of the liver was induced for 60 min; it was followed by reperfusion for 24 hr. In some rats, endothelin-1 antiserum or control serum without endothelin-1-blocking activity was administered intravenously just before reperfusion. Rats were divided into three groups: an ischemia/reperfusion group that was injected with control serum, an endothelin-1 antiserum-treated group and a sham-operated group. Endothelin-1 concentrations in blood collected from the suprahepatic vena cava were measured before and after ischemia/reperfusion by use of a sandwich enzyme immunoassay. Index of blood volume in regional hepatic tissue and index of blood oxygenation in regional hepatic tissue were assessed with an organ reflectance spectrophotometry system before and at 5 min and 1, 2, and 24 hr after reperfusion. The endothelin-1 concentration in the ischemia/reperfusion group started to rise immediately at onset of reperfusion from basal values around 1 pg/ml and reached a value of 5 to 6 pg/ml 5 min after reperfusion; it was maintained at significantly high levels during the reperfusion period compared with the sham-operated group. Hepatic microcirculatory disturbance indicated by lowered index of blood volume in regional hepatic tissue and index of blood oxygenation in regional hepatic tissue levels was observed in the early phase of reperfusion in the ischemia/reperfusion group.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasoactive effect of endothelin-1 on rat liver in vivo

The purpose of this study was to evaluate the role of endothelin-1 in modulating hepatic microcirculation and liver damage. Rats were infused with endothelin-1 at doses ranging from 30 to 1,000 pmol/kg over 1 min through an indwelling cannula placed in the portal vein. In control rats, saline solution was infused at the same rate. Alterations in hepatic microcirculation were measured with an in vivo microscopy system. Serum lactate dehydrogenase activity, an indicator of hepatic damage, was measured 1 hr after endothelin-1 infusion. Immediately after infusion of endothelin-1, we noted a rapid increase in portal pressure, which remained increased for up to 30 min after endothelin-1 infusion. In contrast, systemic blood pressure remained unchanged, even at 1,000 pmol/kg of endothelin-1. Sinusoidal width was reduced and sinusoidal erythrocyte velocity was diminished in a dose-dependent manner. Oxygen saturation of blood in sinusoids was decreased in a dose-dependent manner, reaching values around 40% of control with 1,000 pmol/kg endothelin-1. The degree of decrease in oxygen saturation of blood in sinusoids had an excellent correlation with the calculated blood flow in the liver tissue. Serum lactate dehydrogenase levels were three to four times control values when endothelin-1 was administered at 1,000 pmol/kg. Thus endothelin-1 decreased hepatic tissue oxygenation associated with sinusoidal vasoconstriction. At high concentrations of endothelin-1, this decrease results in hepatocellular damage.

Role of endogenous endothelin in pathogenesis of ethanol-induced gastric mucosal injury in rats

The major objective of this study was to elucidate the role of endogenous endothelin (ET)-1, a potent vasoconstrictor peptide, in the pathogenesis of ethanol (EtOH)-induced gastric mucosal injury. Two series of experiments were performed in anesthetized rats. First, we examined the time course of relationships among changes in ET-1 concentrations in gastric mucosal and portal plasma, gastric mucosal hemodynamics, and mucosal damage produced by EtOH. Intragastric EtOH stimulated release of endogenous ET-1 in gastric mucosal tissue. Plasma ET-1 concentrations in the portal vein also increased after intragastric EtOH administration. ET-1 concentrations in gastric mucosal tissue and portal plasma increased significantly before gastric mucosal hemorrhagic damage occurred. Moreover, 30 min after EtOH administration there were significant correlations between gastric mucosal ET-1 concentrations and both area of gastric hemorrhagic damage as well as concentration of EtOH administered intragastrically. After intragastric EtOH administration, increase in gastric mucosal hemoglobin concentration and decrease in gastric mucosal hemoglobin oxygen saturation, estimated using reflectance spectrophotometry, occurred within 2.5 min and continued throughout the experiments. The time course of microcirculatory changes correlated closely with increases in gastric mucosal ET-1 and portal plasma ET-1 concentrations after intragastric EtOH administration. Gastric microcirculatory disturbances induced by EtOH were associated with significant decreases in gastric mucosal ATP content. Second, we examined whether pretreatment with anti-ET-1 antibody protected against EtOH-induced mucosal injury by improving mucosal microcirculation. Pretreatment with anti-ET-1 antibody microscopically and macroscopically reduced gastric mucosal hemorrhagic damage induced by EtOH and significantly reduced EtOH-induced gastric microcirculatory disturbances and decreases in gastric mucosal ATP.(ABSTRACT TRUNCATED AT 250 WORDS)

Roles of endothelin-1 and nitric oxide in the mechanism for ethanol-induced vasoconstriction in rat liver

This study was designed to investigate the mechanism for ethanol-induced hepatic vasoconstriction in isolated perfused rat liver. Upon initiation of ethanol infusion into the portal vein at concentrations ranging from 25 to 100 mM, portal pressure began to increase in a concentration-dependent manner and reached maximal levels in 2-5 min (initial phase), followed by a gradual decrease over the period of ethanol infusion (escape phenomenon). Endothelin-1 antiserum significantly inhibited this ethanol-induced hepatic vasoconstriction by 45-80%. Cessation of infusion of endothelin-1 antiserum was followed by a subsequent increase in portal pressure. On the other hand, when a nitric oxide synthesis inhibitor, NG-monomethyl-L-arginine (L-NMMA), was infused into the portal vein simultaneously with ethanol, the initial phase of the response of portal pressure to ethanol was not altered and the peak values of portal pressure remained unchanged. However, after the peak increase in portal pressure, the rate of decrease was less than in the absence of L-NMMA. Thus, L-NMMA diminished the escape phenomenon and sustained the vasoconstriction. This study supports the hypothesis that two endothelium-derived vasoactive factors, endothelin-1 and nitric oxide, regulate hepatic vascular tone in the presence of ethanol.

Effect of intravascular ethanol on modulation of gastric mucosal integrity: possible role of endothelin-1

The influences of intravascular ethanol on gastric mucosal integrity and its relation to gastric circulation were investigated in rats. Ulcer formation of the gastric mucosa correlated with the blood ethanol concentration in the presence of 150 mM HCl in the rat stomach. Furthermore, the gastric mucosal hemoglobin concentration (IHb) and hemoglobin oxygen saturation (ISO2), estimated using organ reflectance spectrophotometry, decreased in a concentration-dependent manner with blood ethanol. In isolated, vascularly perfused rabbit stomach, various concentrations (10-400 mM) of ethanol infused into the celiac artery increased the perfusion pressure and released endothelin-1 (ET-1) from the gastric vasculature in a concentration-dependent manner. Moreover, a significant correlation existed between changes in the perfusion pressure and ET-1 concentration in effluents from the gastric vasculature. Furthermore, anti-ET-1 antibody reduced 100 mM ethanol-induced vasoconstriction in a concentration-dependent manner. The results indicate that intravascular ethanol increases the susceptibility of gastric mucosa to injury induced by intraluminal HCl by causing gastric vasoconstriction mediated by ET-1. Thus intravascular ethanol may play an important role in the mechanism of ethanol-induced gastric mucosal injury.

Ethanol stimulates immunoreactive endothelin-1 and -2 release from cultured human umbilical vein endothelial cells

The present study employed enzyme-immunoassay to examine the effect of ethanol on endothelin-1 and/or -2(ET1 + 2) release from human umbilical vein endothelial cells. Thirty minutes of exposure to ethanol increased the release of immunoreactive ET1 + 2 from cultured endothelial cells in a dose-dependent manner. However, ethanol at concentrations of less than 400 mM did not induce any LDH release from the endothelial cells. Trypan blue exclusion test revealed that 400 mM solution of ethanol decreased the cell viability to 7.7%. Thus, ethanol was found to directly stimulate ET1 + 2 release from cultured human umbilical vein endothelial cells. This reaction of vascular endothelial cells against ethanol may be related to ethanol-induced cardiovascular diseases such as hypertension, myocardial infarction and stroke, as well as fatal alcohol syndrome.