NKG2D-CAR memory T cells target pediatric T-cell acute lymphoblastic leukemia in vitro and in vivo but fail to eliminate leukemia initiating cells

Introduction

Refractory/relapsed pediatric acute leukemia are still clinically challenging and new therapeutic strategies are needed. Interactions between Natural Killer Group 2D (NKG2D) receptor, expressed in cytotoxic immune cells, and its ligands (NKG2DL), which are upregulated in leukemic blasts, are important for anti-leukemia immunosurveillance. Nevertheless, leukemia cells may develop immunoescape strategies as NKG2DL shedding and/or downregulation.

Methods

In this report, we analyzed the anti-leukemia activity of NKG2D chimeric antigen receptor (CAR) redirected memory (CD45RA-) T cells in vitro and in a murine model of T-cell acute lymphoblastic leukemia (T-ALL). We also explored in vitro how soluble NKG2DL (sNKG2DL) affected NKG2D-CAR T cells' cytotoxicity and the impact of NKG2D-CAR T cells on Jurkat cells gene expression and in vivo functionality.

Results

In vitro, we found NKG2D-CAR T cells targeted leukemia cells and showed resistance to the immunosuppressive effects exerted by sNKG2DL. In vivo, NKG2D-CAR T cells controlled T cell leukemia burden and increased survival of the treated mice but failed to cure the animals. After CAR T cell treatment, Jurkat cells upregulated genes related to proliferation, survival and stemness, and in vivo, they exhibited functional properties of leukemia initiating cells.

Discussion

The data here presented suggest, that, in combination with other therapeutic approaches, NKG2D-CAR T cells could be a novel treatment for pediatric T-ALL.

Overcoming tumor resistance mechanisms in CAR-NK cell therapy

Despite the impressive results of autologous CAR-T cell therapy in refractory B lymphoproliferative diseases, CAR-NK immunotherapy emerges as a safer, faster, and cost-effective approach with no signs of severe toxicities as described for CAR-T cells. Permanently scrutinized for its efficacy, recent promising data in CAR-NK clinical trials point out the achievement of deep, high-quality responses, thus confirming its potential clinical use. Although CAR-NK cell therapy is not significantly affected by the loss or downregulation of its CAR tumor target, as in the case of CAR-T cell, a plethora of common additional tumor intrinsic or extrinsic mechanisms that could also disable NK cell function have been described. Therefore, considering lessons learned from CAR-T cell therapy, the emergence of CAR-NK cell therapy resistance can also be envisioned. In this review we highlight the processes that could be involved in its development, focusing on cytokine addiction and potential fratricide during manufacturing, poor tumor trafficking, exhaustion within the tumor microenvironment (TME), and NK cell short in vivo persistence on account of the limited expansion, replicative senescence, and rejection by patient’s immune system after lymphodepletion recovery. Finally, we outline new actively explored alternatives to overcome these resistance mechanisms, with a special emphasis on CRISPR/Cas9 mediated genetic engineering approaches, a promising platform to optimize CAR-NK cell function to eradicate refractory cancers.

Isolation of Functional SARS-CoV-2 Antigen-Specific T-Cells with Specific Viral Cytotoxic Activity for Adoptive Therapy of COVID-19

In order to demonstrate the feasibility of preparing clinical-grade SARS-CoV-2-specific T-cells from convalescent donors and the ability of these cells to neutralize the virus in vitro, we used blood collected from two COVID-19 convalescent donors (before and after vaccination) that was stimulated with specific SARS-CoV-2 peptides followed by automated T-cell isolation using the CliniMacs Prodigy medical device. To determine cytotoxic activity, HEK 293T cells were transfected to express the SARS-CoV-2 M protein, mimicking SARS-CoV-2 infection. We were able to quickly and efficiently isolate SARS-CoV-2-specific T lymphocytes from both donors before and after they received the Pfizer-BioNTech vaccine. Althoughbefore vaccination, the final product contained up to 7.42% and 30.19% of IFN-γ+ CD3+ T-cells from donor 1 and donor 2, respectively, we observed an enrichment of the IFN-γ+ CD3+ T-cells after vaccination, reaching 70.47% and 42.59%, respectively. At pre-vaccination, the isolated SARS-CoV-2-specific T-cells exhibited cytotoxic activity that was significantly higher than that of unstimulated controls (donor 2: 15.41%, p-value 3.27 × 10⁻³). The cytotoxic activity of the isolated SARS-CoV-2-specific T-cells also significantly increased after vaccination (donor 1: 32.71%, p-value 1.44 × 10⁻⁵; donor 2: 33.38%, p-value 3.13 × 10⁻⁶). In conclusion, we demonstrated that SARS-CoV-2-specific T-cells can quickly and efficiently be stimulated from the blood of convalescent donors using SARS-CoV-2-specific peptides followed by automated isolation. Vaccinated convalescent donors have a higher percentage of SARS-CoV-2-specific T-cells and may be more suitable as donors. Although further studies are needed to assess the clinical utility of the functional isolated SARS-CoV-2-specific T-cells in patients, previous studies using the same stimulation and isolation methods applied to other pathologies support this idea.

Efficacy of Antiviral Treatment in Hepatitis C Virus (HCV)-Driven Monoclonal Gammopathies Including Myeloma

Multiple myeloma (MM) remains an incurable plasma cell malignancy. While its origin is enigmatic, an association with infectious pathogens including hepatitis C virus (HCV) has been suggested. Here we report nine patients with monoclonal gammopathy of undetermined significance (MGUS) or MM with previous HCV infection, six of whom received antiviral treatment. We studied the evolution of the gammopathy disease, according to anti-HCV treatment and antigen specificity of purified monoclonal immunoglobulin, determined using the INNO-LIA™ HCV Score assay, dot-blot assays, and a multiplex infectious antigen microarray. The monoclonal immunoglobulin from 6/9 patients reacted against HCV. Four of these patients received antiviral treatment and had a better evolution than untreated patients. Following antiviral treatment, one patient with MM in third relapse achieved complete remission with minimal residual disease negativity. For two patients who did not receive antiviral treatment, disease progressed. For the two patients whose monoclonal immunoglobulin did not react against HCV, antiviral treatment was not effective for MGUS or MM disease. Our results suggest a causal relationship between HCV infection and MGUS and MM progression. When HCV was eliminated, chronic antigen-stimulation disappeared, allowing control of clonal plasma cells. This opens new possibilities of treatment for MGUS and myeloma.

NKG2D-CAR-transduced natural killer cells efficiently target multiple myeloma

CAR-T-cell therapy against MM currently shows promising results, but usually with serious toxicities. CAR-NK cells may exert less toxicity when redirected against resistant myeloma cells. CARs can be designed through the use of receptors, such as NKG2D, which recognizes a wide range of ligands to provide broad target specificity. Here, we test this approach by analyzing the antitumor activity of activated and expanded NK cells (NKAE) and CD45RA- T cells from MM patients that were engineered to express an NKG2D-based CAR. NKAE cells were cultured with irradiated Clone9.mbIL21 cells. Then, cells were transduced with an NKG2D-4-1BB-CD3z-CAR. CAR-NKAE cells exhibited no evidence of genetic abnormalities. Although memory T cells were more stably transduced, CAR-NKAE cells exhibited greater in vitro cytotoxicity against MM cells, while showing minimal activity against healthy cells. In vivo, CAR-NKAE cells mediated highly efficient abrogation of MM growth, and 25% of the treated mice remained disease free. Overall, these results demonstrate that it is feasible to modify autologous NKAE cells from MM patients to safely express a NKG2D-CAR. Additionally, autologous CAR-NKAE cells display enhanced antimyeloma activity demonstrating that they could be an effective strategy against MM supporting the development of NKG2D-CAR-NK-cell therapy for MM.

Natural killer cells efficiently target multiple myeloma clonogenic tumor cells

The multiple myeloma (MM) landscape has changed in the last few years, but most patients eventually relapse because current treatment modalities do not target clonogenic stem cells, which are drug-resistant and can self-renew. We hypothesized that side population (SP) cells represent myeloma clonogenic stem cells and, searching for new treatment strategies, analyzed the anti-myeloma activity of natural killer (NK) cells against clonogenic cells. Activated and expanded NK cells (NKAE) products were obtained by co-culturing NK cells from MM patients with K562-mb15-41BBL cell line and characterized by flow cytometry. Functional experiments against MM cells were performed by Eu-TDA release assays and methylcellulose clonogenic assays. Side population was detected by Dye Cycle Violet labeling and then characterized by flow cytometry and RNA-Seq. Self-renewal capacity was tested by clonogenic assays. Sorting of both kind of cells was performed for time-lapse microscopy experiments. SP cells exhibited self-renewal potential and overexpressed genes involved in stem cell metabolism. NK cells from MM patients exhibited dysregulation and had lower anti-tumor potential against clonogenic cells than healthy donors’ NK cells. Patients’ NK cells were activated and expanded. These cells recovered cytotoxic activity and could specifically destroy clonogenic myeloma cells. They also had a highly cytotoxic phenotype expressing NKG2D receptor. Blocking NKG2D receptor decreased NK cell activity against clonogenic myeloma cells, and activated NK cells were able to destroy SP cells, which expressed NKG2D ligands. SP cells could represent the stem cell compartment in MM. This is the first report describing NK cell activity against myeloma clonogenic cells.

Phase 2 Clinical Trial of Infusing Haploidentical K562-mb15-41BBL-Activated and Expanded Natural Killer Cells as Consolidation Therapy for Pediatric Acute Myeloblastic Leukemia

BACKGROUND

Acute myeloid leukemia (AML) accounts for approximately 20% of pediatric leukemia cases; 30% of these patients experience relapse. The antileukemia properties of natural killer (NK) cells and their safety profile have been reported in AML therapy. We proposed a phase 2, open, prospective, multicenter, nonrandomized clinical trial for the adoptive infusion of haploidentical K562-mb15-41BBL-activated and expanded NK (NKAE) cells as a consolidation strategy for children with favorable and intermediate risk AML in first complete remission after chemotherapy (NCT02763475).

PATIENTS AND METHODS

Before the NKAE cell infusion, patients underwent a lymphodepleting regimen. After the NKAE cell infusion, patients were administered low doses (1 × 10⁶/IU/m²) of subcutaneous interleukin-2. The primary study endpoint was AML relapse-free survival. We needed to include 35 patients to demonstrate a 50% reduction in relapses.

RESULTS

Seven patients (median age, 7.4 years; range, 0.78-15.98 years) were administered 13 infusions of NKAE cells, with a median of 36.44 × 10⁶ cells/kg (range, 6.92 × 10⁶ to 193.2 × 10⁶ cells/kg). We observed chimerism in 4 patients (median chimerism, 0.065%; range, 0.05-0.27%). After a median follow-up of 33 months, the disease of 6 patients (85.7%) remained in complete remission. The 3-year overall survival was 83.3% (95% confidence interval, 68.1-98.5), and the cumulative 3-year relapse rate was 28.6% (95% confidence interval, 11.5-45.7). The study was terminated early because of low patient recruitment.

CONCLUSION

This study emphasizes the difficulties in recruiting patients for cell therapy trials, though NKAE cell infusion is safe and feasible. However, we cannot draw any conclusions regarding efficacy because of the small number of included patients and insufficient biological markers.

Optimizing the Procedure to Manufacture Clinical-Grade NK Cells for Adoptive Immunotherapy

Simple Summary

Natural Killer cells have shown promise to treat different malignancies. Several methods have been described to obtain fully activated NK cells for clinical use. Here, we use different cell culture media and different artificial antigen presenting cells to optimize a GMP compliant manufacturing method to obtain activated and expanded NK cells suitable for clinical use.

Abstract

Natural killer (NK) cells represent promising tools for cancer immunotherapy. We report the optimization of an NK cell activation–expansion process and its validation on clinical-scale. Methods: RPMI-1640, stem cell growth medium (SCGM), NK MACS and TexMACS were used as culture mediums. Activated and expanded NK cells (NKAE) were obtained by coculturing total peripheral blood mononuclear cells (PBMC) or CD45RA⁺ cells with irradiated K562mbIL15-41BBL or K562mbIL21-41BBL. Fold increase, NK cell purity, activation status, cytotoxicity and transcriptome profile were analyzed. Clinical-grade NKAE cells were manufactured in CliniMACS Prodigy. Results: NK MACS and TexMACs achieved the highest NK cell purity and lowest T cell contamination. Obtaining NKAE cells from CD45RA⁺ cells was feasible although PBMC yielded higher total cell numbers and NK cell purity than CD45RA⁺ cells. The highest fold expansion and NK purity were achieved by using PBMC and K562mbIL21-41BBL cells. However, no differences in activation and cytotoxicity were found when using either NK cell source or activating cell line. Transcriptome profile showed to be different between basal NK cells and NKAE cells expanded with K562mbIL21-41BBL or K562mbIL15-41BBL. Clinical-grade manufactured NKAE cells complied with the specifications from the Spanish Regulatory Agency. Conclusions: GMP-grade NK cells for clinical use can be obtained by using different starting cells and aAPC.

MEK inhibition enhances the response to tyrosine kinase inhibitors in acute myeloid leukemia

FMS-like tyrosine kinase 3 (FLT3) is a key driver of acute myeloid leukemia (AML). Several tyrosine kinase inhibitors (TKIs) targeting FLT3 have been evaluated clinically, but their effects are limited when used in monotherapy due to the emergence of drug-resistance. Thus, a better understanding of drug-resistance pathways could be a good strategy to explore and evaluate new combinational therapies for AML. Here, we used phosphoproteomics to identify differentially-phosphorylated proteins in patients with AML and TKI resistance. We then studied resistance mechanisms in vitro and evaluated the efficacy and safety of rational combinational therapy in vitro, ex vivo and in vivo in mice. Proteomic and immunohistochemical studies showed the sustained activation of ERK1/2 in bone marrow samples of patients with AML after developing resistance to FLT3 inhibitors, which was identified as a common resistance pathway. We examined the concomitant inhibition of MEK-ERK1/2 and FLT3 as a strategy to overcome drug-resistance, finding that the MEK inhibitor trametinib remained potent in TKI-resistant cells and exerted strong synergy when combined with the TKI midostaurin in cells with mutated and wild-type FLT3. Importantly, this combination was not toxic to CD34+ cells from healthy donors, but produced survival improvements in vivo when compared with single therapy groups. Thus, our data point to trametinib plus midostaurin as a potentially beneficial therapy in patients with AML.

Protein Carbonylation in Patients with Myelodysplastic Syndrome: An Opportunity for Deferasirox Therapy

Control of oxidative stress in the bone marrow (BM) is key for maintaining the interplay between self-renewal, proliferation, and differentiation of hematopoietic cells. Breakdown of this regulation can lead to diseases characterized by BM failure such as the myelodysplastic syndromes (MDS). To better understand the role of oxidative stress in MDS development, we compared protein carbonylation as an indicator of oxidative stress in the BM of patients with MDS and control subjects, and also patients with MDS under treatment with the iron chelator deferasirox (DFX). As expected, differences in the pattern of protein carbonylation were observed in BM samples between MDS patients and controls, with an increase in protein carbonylation in the former. Strikingly, patients under DFX treatment had lower levels of protein carbonylation in BM with respect to untreated patients. Proteomic analysis identified four proteins with high carbonylation levels in MDS BM cells. Finally, as oxidative stress-related signaling pathways can modulate the cell cycle through p53, we analyzed the expression of the p53 target gene p21 in BM cells, finding that it was significantly upregulated in patients with MDS and was significantly downregulated after DFX treatment. Overall, our results suggest that the fine-tuning of oxidative stress levels in the BM of patients with MDS might control malignant progression.

GMP-Compliant Manufacturing of NKG2D CAR Memory T Cells Using CliniMACS Prodigy

Natural killer group 2D (NKG2D) is a natural killer (NK) cell-activating receptor that recognizes different stress-induced ligands that are overexpressed in a variety of childhood and adult tumors. NKG2D chimeric antigen receptor (CAR) T cells have shown potent anticancer effects against different cancer types. A second-generation NKG2D CAR was generated by fusing full-length human NKG2D to 4-1BB costimulatory molecule and CD3ζ signaling domain. Patient-derived CAR T cells show limitations including inability to manufacture CAR T cells from the patients' own T cells, disease progression, and death prior to return of engineered cells. The use of allogeneic T cells for CAR therapy could be an attractive alternative, although undesirable graft vs. host reactions may occur. To avoid such adverse effects, we used CD45RA⁻ memory T cells, a T-cell subset with less alloreactivity, as effector cells to express NKG2D CAR. In this study, we developed a protocol to obtain large-scale NKG2D CAR memory T cells for clinical use by using CliniMACS Prodigy, an automated closed system compliant with Good Manufacturing Practice (GMP) guidelines. CD45RA⁺ fraction was depleted from healthy donors' non-mobilized apheresis using CliniMACS CD45RA Reagent and CliniMACS Plus device. A total of 10⁸ CD45RA⁻ cells were cultured in TexMACS media supplemented with 100 IU/mL IL-2 and activated at day 0 with T Cell TransAct. Then, we used NKG2D-CD8TM-4-1BB-CD3ζ lentiviral vector for cell transduction (MOI = 2). NKG2D CAR T cells expanded between 10 and 13 days. Final cell products were analyzed to comply with the specifications derived from the quality and complementary controls carried out in accordance with the instructions of the Spanish Regulatory Agency of Medicines and Medical Devices (AEMPS) for the manufacture of investigational advanced therapy medicinal products (ATMPs). We performed four validations. The manufacturing protocol here described achieved large numbers of viable NKG2D CAR memory T cells with elevated levels of NKG2D CAR expression and highly cytotoxic against Jurkat and 531MII tumor target cells. CAR T cell final products met release criteria, except for one showing myc overexpression and another with viral copy number higher than five. Manufacturing of clinical-grade NKG2D CAR memory T cells using CliniMACS Prodigy is feasible and reproducible, widening clinical application of CAR T cell therapies.

Novel treatment strategy with autologous activated and expanded natural killer cells plus anti-myeloma drugs for multiple myeloma

This proof-of-concept single-arm open-label phase I clinical trial (NCT02481934) studied the safety and efficacy of multiple infusions of activated and expanded natural killer (NKAE) cells in combination with anti-myeloma drugs in multiple myeloma patients. It included five patients with relapsed or refractory MM who had received two to seven prior lines of therapy; NK cells were expanded for 3 weeks with K562-mb15-41BBL cells. Patients received four cycles of pharmacological treatment with two infusions of 7.5 × 10⁶ NKAEs/kg per cycle. NKAE generation, expansion, and NK monitoring was assessed using flow cytometry. Eighteen clinical-grade NKAE cell GMP-grade products were generated to obtain 627 × 10⁶ NKAEs (range: 315–919 × 10⁶) for the first infusion and 943 × 10⁶ (range: 471–1481 × 10⁶) for the second infusion with 90% (±7%) purity. Neutropenia grade II occurred in two patients and was related to chemotherapy. Of the five patients, four showed disease stabilization before the end of NKAE treatment, and two showed a 50% reduction in bone marrow infiltration and a long-term (>1 y) response. The NKAE cells had a highly cytotoxic phenotype and high cytotoxicity in vitro. Infused NKAE cells were detected in bone marrow and peripheral blood after infusions. Ex vivo expansion of autologous NK cells is feasible, NKAE cells are clinically active and the multiple infusions are well tolerated in patients with relapsed or refractory myeloma.

Visfatin impairs endothelium-dependent relaxation in rat and human mesenteric microvessels through nicotinamide phosphoribosyltransferase activity

Visfatin, also known as extracellular pre-B-cell colony-enhancing factor (PBEF) and nicotinamide phosphoribosyltransferase (Nampt), is an adipocytokine whose circulating levels are enhanced in metabolic disorders, such as type 2 diabetes mellitus and obesity. Circulating visfatin levels have been positively associated with vascular damage and endothelial dysfunction. Here, we investigated the ability of visfatin to directly impair vascular reactivity in mesenteric microvessels from both male Sprague-Dawley rats and patients undergoing non-urgent, non-septic abdominal surgery. The pre-incubation of rat microvessels with visfatin (50 and 100 ng/mL) did not modify the contractile response to noradrenaline (1 pmol/L to 30 µmol/L), as determined using a small vessel myograph. However, visfatin (10 to 100 ng/mL) concentration-dependently impaired the relaxation to acetylcholine (ACh; 100 pmol/L to 3 µmol/L), without interfering with the endothelium-independent relaxation to sodium nitroprusside (1 nmol/L to 3 µmol/L). In both cultured human umbilical vein endothelial cells and rat microvascular preparations, visfatin (50 ng/mL) stimulated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, as determined by lucigenin-derived chemiluminiscence. The relaxation to ACh impaired by visfatin was restored by the NADPH oxidase inhibitor apocynin (10 µmol/L). Additionally, the Nampt inhibitor APO866 (10 mmol/L to 10 µmol/L), but not an insulin receptor-blocking antibody, also prevented the stimulation of NADPH oxidase and the relaxation impairment elicited by visfatin. Accordingly, the product of Nampt activity nicotinamide mononucleotide (100 nmol/L to 1 mmol/L) stimulated endothelial NADPH oxidase activity and concentration-dependently impaired ACh-induced vasorelaxation. In human mesenteric microvessels pre-contracted with 35 mmol/L potassium chloride, the endothelium-dependent vasodilation to bradykinin (1 nmol/L to 3 µmol/L) was equally impaired by visfatin and restored upon co-incubation with APO866. In conclusion, visfatin impairs endothelium-dependent relaxation through a mechanism involving NADPH oxidase stimulation and relying on Nampt enzymatic activity, and therefore arises as a potential new player in the development of endothelial dysfunction.

Nitric oxide synthase II mRNA expression in cardiac tissue of patients with heart failure undergoing cardiac transplantation

OBJECTIVES

To examine whether inducible nitric oxide synthase is expressed in myocardial tissue of patients with heart failure.

BACKGROUND

There is increasing evidence that alterations in nitric oxide synthesis are of pathophysiologic importance in heart failure. Nitric oxide (NO) can exert negative inotropic and cytotoxic effects on cardiomyocytes. A number of studies have shown altered nitric oxide production by the endothelial constitutive isoform of nitric oxide synthase (NOS III), but there is little information on the role of NOS II. Expression of NOS II could lead to excessive production of NO in the myocardium and affect cardiac contractility.

METHODS

NOS II mRNA expression in myocardial tissue of 18 patients with idiopathic dilated cardiomyopathy (DCM), 7 patients with ischemic cardiopathy and severe ventricular dysfunction (ISCH), 4 patients with acute myocardial infarction (AMI) and 11 controls. Serum concentration of NO2-/NO3- (NOx) was also measured.

RESULTS

NOS II gene expression occurred in all the patients with DCM, in 1 out of the 7 ISCH patients, in 2 out of the 4 patients with AMI and in none of the controls. Moreover, DCM patients showed a significant 6-fold increase in NOx concentration (253+/-47 nm/ml) as compared to controls (40+/-2 nm/ml) P < 0.001, a phenomenon not observed in ISCH patients (56+/-3 nm/ml).

CONCLUSIONS

NOS II expression occurs in failing human cardiac myocytes and can play an specific role in the pathogenesis of DCM.

Comparison of two aquaretic drugs (niravoline and OPC-31260) in cirrhotic rats with ascites and water retention

kappa-Opioid receptor agonists (niravoline) or nonpeptide antidiuretic hormone (ADH) V2 receptor antagonists (OPC-31260) possess aquaretic activity in cirrhosis; however, there is no information concerning the effects induced by the chronic administration of these drugs under this condition. To compare the renal and hormonal effects induced by the long-term oral administration of niravoline, OPC-31260, or vehicle, urine volume, urinary osmolality, sodium excretion, and urinary excretion of aldosterone (ALD) and ADH were measured in basal conditions and for 10 days after the daily oral administration of niravoline, OPC-31260, or vehicle to cirrhotic rats with ascites and water retention. Creatinine clearance, serum osmolality, ADH mRNA expression, and systemic hemodynamics were also measured at the end of the study. Niravoline increased water excretion, peripheral resistance, serum osmolality, and sodium excretion and reduced creatinine clearance, ALD and ADH excretion, and mRNA expression of ADH. OPC-31260 also increased water metabolism and sodium excretion and reduced urinary ALD, although the aquaretic effect was only evident during the first 2 days, and no effects on serum osmolality, renal filtration, and systemic hemodynamics were observed. Therefore, both agents have aquaretic efficacy, but the beneficial therapeutic effects of the long-term oral administration of niravoline are more consistent than those of OPC-31260 in cirrhotic rats with ascites and water retention.

Gene expression of endothelin-1 and ET(A) and ET(B) receptors in human cirrhosis: relationship with hepatic hemodynamics

Previous experimental studies have suggested that the paracrine endothelin system may participate in the regulation of hepatic hemodynamics in cirrhosis. The present study assesses the relationship between increased portal pressure and preproET-1, ET(A) receptor and ET(B) receptor gene expression in human cirrhosis. PreproET-1, ET(A) receptor and ET(B) receptor mRNA abundance was estimated by quantitative PCR in human hepatic tissue from subjects with normal liver and in cirrhotic patients in whom a hepatic hemodynamic study was performed. The expression of the three transcripts was significantly higher in liver samples of cirrhotic patients than in those obtained from subjects without any histological alteration. Moreover, while no significant correlation was found between preproET-1 mRNA abundance and portal pressure, there was a highly significant direct relationship between ET(A) and ET(B) receptor gene expression and portal pressure in cirrhotic patients. These results indicate that the liver paracrine endothelin system is overactivated in human cirrhosis and that a direct relationship exists between endothelin receptor mRNA abundance and the degree of portal hypertension in these patients.

Nitric oxide production by peritoneal macrophages of cirrhotic rats: a host response against bacterial peritonitis

BACKGROUND & AIMS

Patients and rats with cirrhosis and ascites are prone to develop peritonitis. The aim of this study was to assess whether peritoneal macrophages of cirrhotic rats without peritoneal infection produce nitric oxide and express inducible NO synthase (iNOS).

METHODS

NO2- accumulation produced by macrophages from control rats and cirrhotic rats with ascites was determined. iNOS messenger RNA and protein expression were analyzed by Northern and Western blot and immunocytochemical analysis. The in vivo effects of inhibiting iNOS were investigated by giving the specific iNOS inhibitor L-N-(1-iminoethyl)-lysine (L-NIL) or sterile saline to 9 and 7 cirrhotic rats with ascites, respectively.

RESULTS

Cirrhotic macrophages produced NO2- that was around fourfold greater than that of control macrophages after 30 hours in culture. Northern and Western blot and immunocytochemical analysis showed the presence of iNOS messenger RNA and protein in macrophages of cirrhotic rats. Ascites cultures were positive in all rats administered L-NIL and negative in those administered saline.

CONCLUSIONS

Macrophages of cirrhotic rats produce NO and express iNOS messenger RNA and protein, and these changes are not a consequence of overt bacterial infection. Because iNOS inhibition results in peritoneal infection, these results suggest that iNOS induction in macrophages of cirrhotic rats is a host defense response to prevent bacterial peritonitis.

Effect of bacterial lipopolysaccharide on endothelin-1 production in human vascular endothelial cells

BACKGROUND/AIMS

The plasma levels of endothelin (ET) are 2-5 fold higher in patients with cirrhosis than in healthy subjects. It has been proposed that endotoxemia could be a mechanism responsible for this phenomenon. However, investigations in rats with cirrhosis indicate that a differential regulation for prepro ET-1 mRNA expression occurs in the liver tissue of these animals but not in the aorta or other organs. The aim of the study was to investigate the effect of bacterial lipopolysaccharide (LPS) on endothelin-1 synthesis and release in cultured human vascular endothelial cells (HUVEC).

METHODS

Confluent HUVEC at passage levels 3 and 4 were exposed to increasing doses of LPS (1-1000 ng/ml) for 4 h at 37 degrees C and prepro ET-1 mRNA accumulation and big ET-1 and ET-1 concentrations in the conditioned medium were measured.

RESULTS

Endotoxin had a dual effect on HUVEC. LPS at doses ranging between 250 and 1000 ng/ml induced a progressive diminution in ET-1 concentration in the culture medium. However, lower LPS concentrations dose-dependently increased big ET-1 and ET-1 release by HUVEC without altering prepro ET-1 mRNA expression.

CONCLUSIONS

These results suggest that low LPS concentrations promote ET-1 release in HUVEC by a post-transcriptional mechanism located upstream of big ET-1 in the biosynthetic pathway of ET-1. These findings could explain the existence of high circulating levels of ET-1 in cirrhosis in spite of transcriptional activation of prepro ET-1 mRNA only occurring in the liver.

Increased nitric oxide synthase expression in arterial vessels of cirrhotic rats with ascites

Arterial vasodilatation is thought to play a major role in the pathogenesis of systemic hemodynamics and renal disturbances occurring in cirrhotic patients. Recent investigations suggest that an increased vascular nitric oxide (NO) production could be implicated in this abnormality. The current study assessed whether increased expression of inducible and/or endothelial nitric oxide synthase (iNOS and eNOS, respectively) occurs in arterial vessels of cirrhotic rats. The investigation was performed in thoracic and abdominal aortas and mesenteric arteries of 10 control rats and 16 cirrhotic rats with ascites. iNOS and eNOS messenger RNA (mRNA) expression were evaluated by polymerase chain reaction and ribonuclease protection assay, respectively. Endothelial NOS protein expression was assessed by Western blot. No iNOS mRNA was detected in arterial vessels of control rats. In contrast iNOS mRNA was consistently detected in all arteries of cirrhotic rats with ascites, the weakest signal being observed in the thoracic aorta and the strongest in the mesenteric artery. Enhanced eNOS mRNA abundance was found in the aorta of cirrhotic animals as compared with controls. Higher eNOS protein expression was noted in the thoracic aorta of cirrhotic rats. These results indicate the existence of increased eNOS and iNOS expression in arterial vessels of cirrhotic rats, suggesting that transcriptional activation of vascular NOSs and the associated nitric oxide hyperproduction may be of major importance in the pathogenesis of arterial vasodilation in cirrhosis.

Increased nitric oxide synthase expression in arterial vessels of cirrhotic rats with ascites

Arterial vasodilatation is thought to play a major role in the pathogenesis of systemic hemodynamics and renal disturbances occurring in cirrhotic patients. Recent investigations suggest that an increased vascular nitric oxide (NO) production could be implicated in this abnormality. The current study assessed whether increased expression of inducible and/or endothelial nitric oxide synthase (iNOS and eNOS, respectively) occurs in arterial vessels of cirrhotic rats. The investigation was performed in thoracic and abdominal aortas and mesenteric arteries of 10 control rats and 16 cirrhotic rats with ascites. iNOS and eNOS messenger RNA (mRNA) expression were evaluated by polymerase chain reaction and ribonuclease protection assay, respectively. Endothelial NOS protein expression was assessed by Western blot. No iNOS mRNA was detected in arterial vessels of control rats. In contrast iNOS mRNA was consistently detected in all arteries of cirrhotic rats with ascites, the weakest signal being observed in the thoracic aorta and the strongest in the mesenteric artery. Enhanced eNOS mRNA abundance was found in the aorta of cirrhotic animals as compared with controls. Higher eNOS protein expression was noted in the thoracic aorta of cirrhotic rats. These results indicate the existence of increased eNOS and iNOS expression in arterial vessels of cirrhotic rats, suggesting that transcriptional activation of vascular NOSs and the associated nitric oxide hyperproduction may be of major importance in the pathogenesis of arterial vasodilation in cirrhosis.

Aquaretic effect of the kappa-opioid agonist RU 51599 in cirrhotic rats with ascites and water retention

BACKGROUND & AIMS

It has recently been described that kappa-opioid receptor agonists inhibit antidiuretic hormone secretion and promote water excretion in humans and experimental animals. The aim of this study was to evaluate the aquaretic efficacy of the kappa-opioid receptor agonist RU 51599 in conscious cirrhotic rats with ascites and water retention.

METHODS

In protocol 1, arterial pressure, heart rate, and renal water metabolism were measured in basal conditions and then were measured for 120 minutes after the administration of Ringer's solution (n = 8; 0.4 mL) or RU 51599 (n = 7; 1 mg/kg). In protocol 2, plasma antidiuretic hormone concentration was measured (n = 6) before and 60 minutes after administration of RU 51599 (1 mg/kg). In protocol 3, the effect of RU 51599 (n = 9; 1 mg/kg) was compared with that of the V2-receptor antagonist SKF 100398 (n = 9; 30 micrograms/kg).

RESULTS

RU 51599 administration induced a profound diuretic and aquaretic effect without altering arterial pressure and heart rate. In protocol 2, the kappa-opioid agonist reduced by about 50% plasma antidiuretic hormone levels (from 6.6 +/- 0.9 to 3.4 +/- 0.6 pg/mL; P < 0.05). Finally, the improvement in renal water metabolism induced by RU 51599 was similar to that produced by the V2-receptor antagonist.

CONCLUSIONS

RU 51599 has a potent aquaretic effect in cirrhotic rats with water retention, suggesting that kappa-opioid receptor agonists may be useful for the treatment of water retention and dilutional hyponatremia in cirrhosis.

Endothelin 1 does not play a major role in the homeostasis of arterial pressure in cirrhotic rats with ascites

BACKGROUND/AIMS

Patients with cirrhosis and ascites have increased plasma levels of endothelin, a powerful vasoconstrictor peptide. This study assessed the mechanisms underlying this phenomenon.

METHODS

Plasma endothelin was measured in control rats and cirrhotic rats with and without ascites. In addition, the tissue concentration of endothelin and endothelin 1 messenger RNA (mRNA) and the effect of an endothelin A receptor antagonist on arterial and portal pressure were assessed in cirrhotic rats with ascites and control rats.

RESULTS

Plasma endothelin levels were significantly higher in cirrhotic rats with ascites (24.5 +/- 2.8 pg/mL; P < 0.001) than in cirrhotic rats without ascites and control rats (7.9 +/- 2.0 and 5.8 +/- 0.9 pg/mL, respectively). In animals with ascites, endothelin and endothelin 1 mRNA content in the lung, kidney, and aorta was similar to that of the controls. In contrast, higher endothelin content (0.567 +/- 0.217 vs. 0.045 +/- 0.002 pg/mg protein; P < 0.05) and endothelin 1 mRNA was observed in hepatic tissue of rats with cirrhosis and ascites. Endothelin A receptor blockade was not associated with significant changes in arterial and portal pressure in any group of animals.

CONCLUSIONS

Increased endothelin 1 mRNA and endothelin production occurs in the livers of cirrhotic rats with ascites. In addition, our findings suggest that endothelin is not involved with the homeostasis of arterial or portal pressure in cirrhosis with ascites.

Intracellular calcium concentration in vascular smooth muscle cells of rats with cirrhosis

A decreased pressor response to endogenous vasoconstrictors, such as angiotensin II and vasopressin, is a characteristic finding in cirrhosis with ascites; this has been considered as partially responsible for the arteriolar vasodilation present in this disease. Previous investigations suggested that this abnormality is due to a post-receptor defect leading to altered intracellular Ca2+ mobilization. To assess this hypothesis, vascular responsiveness to angiotensin II (3.10(-8) M) and intracellular Ca2+ concentration in basal conditions and following angiotensin II (1-100 nM) and vasopressin stimulation (100 nM) were measured in aortic rings and in primary cultured aortic vascular smooth muscle cells, respectively. The study was carried out in 43 control rats and 40 rats with CCl4-induced cirrhosis and ascites. Cells were grown to confluence on glass cover slips and then loaded with Fura-2, a fluorescent intracellular Ca2+ indicator, for continuous monitoring of intracellular Ca2+ concentration. A decreased constrictor response to angiotensin II was detected in cirrhotic aortic rings in comparison to control rings (increase in tension: 31 +/- 5 vs 79 +/- 14 mg, p < 0.005). No differences in intracellular Ca2+ concentration between cirrhotic and control cells were observed in basal conditions (104 +/- 6 and 100 +/- 3 nM, respectively). Angiotensin II administration to cirrhotic vascular smooth muscle cells had a dose-dependent biphasic effect consisting of a rapid increase, followed by return to a sustained level significantly higher than the basal value. This response was identical to that observed in control vascular smooth muscle cells. Similar findings were obtained following vasopressin stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)