In vitro Effect of Carvedilol on Professional Phagocytes

AIM

Superfluous reactive nitrogen and oxygen species generation is implicated in the damage of tissues at sites of inflammation where activated neutrophils and macrophages are involved. This study was conducted to investigate whether the beneficial effects of carvedilol involve modulation of respiratory burst, degranulation-myeloperoxidase release and inducible nitric oxide synthase (iNOS) expression.

METHODS

Spectrophotometry and chemiluminescence were used to evaluate the effect of carvedilol on opsonized zymosan (0.5 mg/ml)- or N-formyl-methionyl-leucyl-phenyl-alanine (fMLP, 0.1 micromol/l)-stimulated superoxide generation and myeloperoxidase release in human neutrophils. Western blot analysis was used for iNOS expression and Griess reagent for nitric oxide production in RAW 264.7 macrophages (lipopolysaccharide (0.1 microg/ml) stimulated).

RESULTS

Carvedilol (10 and 100 micromol/l) significantly decreased opsonized zymosan- and fMPL-stimulated superoxide generation and myeloperoxidase release. Carvedilol (100 micromol/l) enhanced the effect of wortmannin (50 nmol/l), a specific inhibitor of 1-phosphatidylinositol 3-kinase and decreased iNOS expression and nitric oxide production.

CONCLUSION

Carvedilol appears to have a non-specific effect on membranes and to interfere with the phospholipase D signaling pathway, with subsequent inhibition of reactive oxygen species generation and myeloperoxidase release, without affecting iNOS expression.

On the pharmacology and toxicology of neutrophils

OBJECTIVES

To study the effect of H1-antihistamines dithiaden (Dit) and loratadine (Lor) and compare it with that of histamine (His) on phorbolmyristate acetate (PMA) stimulated chemiluminescence (CL) of whole blood, isolated neutrophils, release of myeloperoxidase (MPO), and on superoxide (SO) generation.

METHODS

Luminol- and isoluminol-enhanced CL was applied for measuring the oxidative burst, spectrophotometry was used for determination of MPO (o-dianisidine) and SO generation (superoxide dismutase inhibition of cytochrome c).

RESULTS

Dit and Lor dose-dependently inhibited CL of whole blood and significantly decreased oxidative burst both at the extra- and intracellular sites of neutrophils. Release of MPO was decreased with both drugs tested in 10-times lower concentrations than was SO inhibition. Histamine (His) was much less effective in the inhibition of the parameters investigated.

CONCLUSIONS

Histaminergic drugs of the 1st generation inhibited oxidative burst of human phagocytes in whole blood and in isolated neutrophils. The rank order of potency to inhibit CL, MPO release and SO generation in PMA stimulated phagocytes was: Dit>Lor>His.

Effect of carvedilol on reactive oxygen species and enzymes linking innate and adaptive immunity

OBJECTIVES

Neutrophils and macrophages are critical components of our innate host defenses. They are a potential source of nitric oxide (NO) and superoxide, known to play an important role in many physiological processes including defense, immune and inflammatory responses. Myeloperoxidase (MPO), a major NO scavenger and a marker of oxidative stress, as well as increased inducible nitric oxide synthase (iNOS) expression, may affect the NO-superoxide balance, critical for cellular redox balance in the cardiovascular system at physiologic conditions. The effect of carvedilol was studied on stimulated superoxide generation, MPO release and iNOS expression in phagocytes by using receptor operating stimuli [N-formyl-Met-Leu-Phe (FMLP), lipopolysaccharide (LPS) and specific inhibitors (wortmannin, propranolol).

METHODS

Superoxide generation was measured as superoxide dismutase inhibitable reduction of cytochrome c (550 nm), MPO activity as the oxidation of o-dianisidine in the presence of hydrogen peroxide in a spectrophotometer Hewlet Packard 8452 A (463 nm). Expression of iNOS (Western-blot analysis) in RAW 264.7 cell line (murine macrophages) was stimulated by lipopolysaccharide (LPS).

RESULTS

Carvedilol dose-dependently decreased superoxide generation and MPO release from intact neutrophils stimulated by FMLP. In the highest concentration tested, carvedilol pronounced the effect of wortmannin [inhibitor of phospholipase D (PLD) regulatory pathway] and significantly decreased LPS stimulated iNOS expression in RAW 264.7 cell line.

CONCLUSION

The conceivable cumulative non-specific membrane effect of carvedilol and its effect on PLD signalling pathway contribute to the decrease of both superoxide generation and MPO release, thus supporting the restoration of NO-superoxide balance.

Extra- and intracellular formation of reactive oxygen species by human neutrophils in the presence of pheniramine, chlorpheniramine and brompheniramine

BACKGROUND

Allergic inflammation was found to be accompanied by activation of neutrophils. Since this resulted in increased formation of reactive oxygen species, the antioxidative activity of antiallergic drugs was considered to decrease the risk of tissue damage. However, if the drug-induced inhibition of radical formation occurred intracellularly, it could disturb regulation of neutrophil functions and decrease bactericidal activity of these cells. Separate analysis of extra- and intracellular activity of antioxidative drugs is thus of particular importance.

OBJECTIVE

To differentiate the effects of three antiallergic H1-antihistamine drugs (pheniramine, chlor- and brompheniramine) on radical formation outside and inside human neutrophils.

METHODS

Formation of reactive oxygen species was determined in vitro using the chemiluminescence method. The chemiluminescence signal, initiated by phorbol-12-myristate-13-acetate, was enhanced either with isoluminol (extracellular) or with luminol in the presence of extracellular scavengers, superoxide dismutase and catalase (intracellular).

RESULTS

The antihistamines tested displayed dual activity - they inhibited the extracellular and potentiated the intracellular chemiluminescence. Chlor- and brompheniramine were found to be more effective than pheniramine.

CONCLUSION

Compared to other H1-antihistamines (such as dithiaden or loratadine, active both extra- and intracellularly), the observed inhibition caused by the pheniramines tested was unique since it occurred selectively outside neutrophils. This might indicate the ability of these drugs to minimise toxic effects of extracellular radicals without affecting intracellular oxidant production involved in regulation of neutrophil functions and in microbial killing.

On the antioxidant activity of carvedilol in human polymorphonuclear leukocytes in vitro and ex vivo

OBJECTIVES

In the present study we investigated whether the beta-adrenoceptor antagonist carvedilol (CARV) [Dilatrend] prevented reactive oxygen metabolite (ROM) production in human polymorphonuclear leukocytes (PMNL) or interfered with ROM already generated. To specify the site of action of CARV, we evaluated its effect on extra- and intracellular ROM generation. In addition, we studied the effect of CARV therapy on ROM production in whole blood obtained from patients with congestive heart failure (CHF) combined with type II diabetes mellitus.

METHODS

ROM generation in whole blood and isolated PMNL was determined after phorbol 12-myristate-13-acetate (PMA-0.05 micromol/l) stimulation by luminol/isoluminol-enhanced chemiluminescence (CL) in the microplate luminometer Immunotech LM-01T.

RESULTS

CARV significantly decreased CL of human whole blood in the concentrations of 10, 20, 50 and 100 micromol/l, both when applied simultaneously and after stimulation. In isolated PMNL, CARV significantly decreased extracellular CL in the concentrations of 50 and 100 micromol/l, intracellular CL was decreased in the concentrations of 20, 50 and 100 micromol/l. The nonstimulated and PMA stimulated CL of whole blood was increased in patients before therapy in comparison with healthy controls. After CARV therapy, 25 mg/day and 50 mg/day, there was a trend to reduce CL as compared to values before therapy.

CONCLUSIONS

In human PMNL, CARV interfered in vitro and ex vivo with ROM generation as well as with already generated ROM, suggestive of its both "preventive" and "therapeutic" effect.

The combined luminol/isoluminol chemiluminescence method for differentiating between extracellular and intracellular oxidant production by neutrophils

To address the question why isoluminol, but not luminol, failed to detect oxidants produced intracellularly, differences between these luminophores were investigated with respect to physicochemical parameters and the character of chemiluminescence signal. Our results showed the isoluminol molecule to be more polar, more hydrophilic and possessing lower ability to form intramolecular bonds than the luminol molecule. Therefore, isoluminol: (i) only slightly pervaded biological membranes; (ii) depended essentially on extracellular peroxidase; (iii) did not produce chemiluminescence in the presence of extracellular scavengers; and (iv) it could be considered a specific detector of extracellular radicals. On the other hand, the physicochemical parameters of luminol and partial resistance of its chemiluminescence to the effect of extracellular inhibitors proved the lipo/hydrophilic character of this luminophore and thus its ability to interact with radicals both outside and inside of cells. The luminol chemiluminescence measured in the presence of extracellular scavengers and the isoluminol chemiluminescence were used with the intention to differentiate the effects of two antihistamine drugs on intra- and extracellular radical formation. In activated human neutrophils, brompheniramine inhibited the extracellular and potentiated the intracellular part of chemiluminescence signal, whereas a reducing effect of loratadine was observed in both compartments.

Influence of carvedilol on superoxide generation and enzyme release from stimulated human neutrophils

Activation of neutrophils induces generation of reactive oxygen species and release of granule enzymes, which not only participate in the bactericidal mechanisms of these cells, but also in possible tissue damage. We studied the effect of carvedilol (CARV) [0.1-100 micromol/l], an antihypertensive and cardiovascular drug with antioxidative properties, on superoxide generation (SO) and myeloperoxidase (MPO) release from isolated human neutrophils stimulated with fMLP, a specific receptor activator, or with PMA, a receptor bypassing stimulus. Unstimulated cells showed neither SO formation nor MPO release after preincubation with drug. CARV decreased fMLP and PMA stimulated MPO release and SO generation dose dependently. The inhibitory effect of CARV may attributed to non-specific action since its effect was not influenced by the type of stimulation. It might inhibit SO generation as well as MPO release either by membrane-operating stimulus (fMLP) or membrane bypassing activator (PMA).

Influence of carvedilol on superoxide generation and enzyme release from stimulated human neutrophils

Activation of neutrophils induces generation of reactive oxygen species and release of granule enzymes, which not only participate in the bactericidal mechanisms of these cells, but also in possible tissue damage. We studied the effect of carvedilol (CARV) [0.1-100 micromol/l], an antihypertensive and cardiovascular drug with antioxidative properties, on superoxide generation (SO) and myeloperoxidase (MPO) release from isolated human neutrophils stimulated with fMLP, a specific receptor activator, or with PMA, a receptor bypassing stimulus. Unstimulated cells showed neither SO formation nor MPO release after preincubation with drug. CARV decreased fMLP and PMA stimulated MPO release and SO generation dose dependently. The inhibitory effect of CARV may attributed to non-specific action since its effect was not influenced by the type of stimulation. It might inhibit SO generation as well as MPO release either by membrane-operating stimulus (fMLP) or membrane bypassing activator (PMA).

[Richter's syndrome (bimorphologic malignant lymphoma)]

Two distinct morphological types of malignant lymphoma in the same patient occur mostly due to transformation of a low grade lymphoma (CLL) into a large--cell non-Hodgkin lymphoma (high-grade lymphoma). Later reports have brough evidence of a clonal relationship between CLL and supervening NHL. The Richter's syndrome was found to be more frequent in patients with CLL displaying either multiple chromosomal aberrations or monoclonal gammapaties. In the last two decades reports have evidenced the existence of two types of the Richter's syndrome: one, the "classical" as a terminal event in a long evolving CLL, the other "variant" as the first clinical manifestation of a previously unrecognized subclinical CLL. Aggressive chemotherapy of CLL play a role in transformation of CLL to Richter's syndrome.

Allogeneic BMT for haematological disorders: single centre experience of University Hospital Bratislava

Data on 65 sibling bone marrow transplantations (BMT) for various hematological disorders are reported. 51 patients had leukemia, 8 severe aplastic anemia, 4 myelodysplastic syndrome, one suffered from non-Hodgkin lymphoma and one from myeloid metaplasia. All but two patients have engrafted. Overall, 43 (66%) of 65 patients were alive 0,03-7,2 years (median not reached) as of June 23, 1997. Median time of observation was 13 months. Outcome of standard risk patients was significantly better than that of high risk patients (p=0,006). Our data confirm, that sibling BMT is an effective treatment modality with acceptable toxicity for younger patients with an early stage of serious hematological disorders.

[Density of adhesive proteins after oral administration of proteolytic enzymes in multiple myeloma]

The authors present information on the presence of adhesive proteins on membranes of myeloma and precursor cells isolated from bone marrow and blood from a group of 33 patients examined by fluorescent flow cytometry. They also compare the density of integrins (CD29, CD49e, CD41, CD51 and CD61) and adhesive proteins from the group of "homing" receptors (CD44) and IgG "superfamily" (LFA-1, LFA-3, ICAM-1, N-CAM) and their changes after a single oral dose of a mixture of proteolytic enzymes (Wobe Mugos, Wobenzym, MUCOS Pharma, FRG). The authors observed a significant drop of CD29, CD54 (ICAM-1), CD58 (LFA-3) after Wobe Mugos, CD49, CD51, CD58 after Wobenzyme. The insignificant decline of density of CD44 on cells, as well as of the soluble receptor of CD44 after oral administration of proteolytic enzymes in serum, incl. the mentioned changes of integrins and other adhesive proteins, indicate the importance of enzyme preparations in the supporting treatment of malignant processes.

[The favorable effect of hydrolytic enzymes in the treatment of immunocytomas and plasmacytomas]

At present attention is focused on research of biomodulating influences on tumorous processes, in particular inhibition of metastatic spread of tumors. In the aetiopathogenesis an important part is played by immune complexes, interaction of cytokines. The authors tested the supporting effect of hydrolytic enzymes in plasmocytoma and immunocytoma. The enzymes were administered along with cytostatic preparations according to the MOCCA pattern. They recorded a more rapid onset and longer persistence of remissions, a marked decline of total proteins, paraproteins, beta-2-microglobulin. Complications associated with paraprotein (hyperviscosity syndrome, nephrotic syndrome, peripheral angiopathy) improved. A combination of chemotherapy and enzymatic treatment proved effective and suitable, in particular for patients with interferon intolerance.