The effect of roxithromycin on the generation of reactive oxygen species in vitro

Effects of clarithromycin on inflammatory cell mediator release and survival

BACKGROUND

Clarithromycin exhibits anti-inflammatory as well as antimicrobial activity, leading to decreased symptoms of asthma and chronic sinusitis. The mode of anti-inflammatory effects of clarithromycin on inflammatory cells is not well understood. We hypothesized that clarithromycin inhibits inflammatory cell mediator release and survival.

METHODS

We investigated the effects of this drug on survival and mediator release from mast cells, eosinophils and neutrophils.

RESULTS

Human eosinophil and neutrophil respiratory burst was inhibited by up to 54% after 1-2 h pretreatment with 100 microg/ml clarithromycin. Similar doses of erythromycin did not affect respiratory burst responses in these cells. Clarithromycin at doses of up to 100 microg/ml had no effect on granule-derived mediators released from mast cells and neutrophils. However, we found that clarithromycin (100 microg/ml) induced cell death in mast cells and eosinophils after 16-48 h incubation.

CONCLUSION

Clarithromycin inhibited inflammatory cell mediator release and survival, which may enhance its ability to reduce the symptoms of chronic sinusitis and asthma.

Roxithromycin suppresses involucrin expression by modulation of activator protein-1 and nuclear factor-kappaB activities of keratinocytes

BACKGROUND

Roxithromycin (RXM), a new 14-member macrolide antibiotic, is effective for chronic airway diseases such as diffuse panbronchiolitis and bronchial asthma. Recent study disclosed that RXM inhibits nuclear factor-kappaB (NF-kappaB)-mediated inflammation. Involucrin is one of the precursor proteins of the cornified cell envelope (CE) and is markedly increased in inflammatory skin diseases such as psoriasis. However, its molecular mechanism of action remains unknown.

OBJECTIVE

To determine the effect of RXM on involucrin expression of keratinocytes.

METHODS

We constructed chloramphenicol acetyltransferase (CAT)-involucrin promoter expression vector and CAT assay was performed. Furthermore, western blot and RT-PCR were performed to examine the expression of involucrin in RXM-treated cultured human keratinocytes.

RESULTS

The increased involucrin expression by 12-O-tetradecanoylphorbol acetate (TPA) was suppressed by 10(-6) M RXM and the maximal inhibitory effect was observed at 48 h. RXM suppressed increased CAT activity by TPA and the effect was not inhibited by H-7 or cafferic acid phenethyl ester (CAPE). Deletion of T1 region (-119 to -113) of involucrin promoter completely abolished TPA-dependent stimulatory and RXM-dependent inhibitory promoter activity. Gel shift assay showed that c-Jun (but not p65) selectively binds to the T1 region. The assay of activator protein-1 (AP-1) and NF-kappaB activities revealed that RXM decreased both transcriptional activities. Co-transfection of c-jun and c-fos expression vectors, or p65 and p50 expression vectors, rescued decreased CAT activity by RXM, respectively.

CONCLUSION

Our study demonstrated for the first time that involucrin expression of keratinocytes is suppressed by RXM through direct inhibition of AP-1 and indirect inhibition of NF-kappaB.

Roxithromycin decreases ultraviolet B irradiation-induced reactive oxygen intermediates production and apoptosis of keratinocytes

BACKGROUND

In addition to their antimicrobial action, roxithromycin (RXM), a new 14-membrane macrolide antibiotics, have immunomodulatory, anti-inflammatory and anti-oxidative activity. Ultraviolet B (UVB) irradiation induces reactive oxygen intermediates and apoptosis of keratinocytes.

OBJECTIVE

To examine the anti-apoptotic and anti-oxidative effect of RXM on UVB-irradiated keratinocytes.

METHODS

UVB-induced apoptosis was determined by cell death assay using crystal violet staining, and DNA fragmentation assay. Superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and calatase activities were measured in UVB-irradiated SV40-trasnformed human keratinocytes (SVHK cells). Detection of superoxide was performed histologically using hydroethidine and colorimetric quantitative assay using ferrous irons. H(2)O(2) was measured by colorimetrical assay.

RESULTS

RXM suppressed UVB-induced apoptosis of SVHK cells. UVB-irradiated SVHK cells showed decreased SOD, GPx, GR, and catalase activities. RXM pretreatment suppressed the decrease in these enzyme activities with the maximal effect detected at 10microM of RXM. The effect was associated with suppression of UVB-induced superoxide and H(2)O(2) production.

CONCLUSION

The present study demonstrated that RXM has anti-apoptotic and anti-oxidative effects against UVB-irradiated keratinocytes.

Effects of roxithromycin on adhesion molecules expressed on endothelial cells of the dermal microvasculature

The objective of the study was to investigate the pharmacological action of roxithromycin, an oral macrolide antibiotic. The effects of roxithromycin on the cytokine-induced expression of endothelial leukocyte adhesion molecule (E-selectin) and intracellular adhesion molecule (ICAM)-1 on endothelial cells of the dermal microvasculature were investigated in vitro using flow cytometry. Roxithromycin at a concentration of 0.5 microgram/ml, which is lower than the therapeutic plasma concentration (ordinary daily dose, 150-300 mg), significantly inhibited the expression of E-selectin and ICAM-1 on endothelial cells of the dermal microvasculature induced by tumour necrosis factor-alpha. We conclude that roxithromycin may exert its anti-inflammatory action by inhibition of the in vivo expression of adhesion molecules on dermal microvascular endothelial cells.

Concentration of roxithromycin in the lesions of acne vulgaris

Roxithromycin, a macrolide antibiotic, is used in the treatment of acne vulgaris, although there have been no reports on its concentration in lesions when administered orally. We investigated the concentration of roxithromycin in acne vulgaris lesions in five patients who received 150 mg roxithromycin orally twice daily for 2 weeks. The mean concentration of roxithromycin in the lesions was 0.54 microgram/ml. These results suggest that roxithromycin accumulates at therapeutic levels in the pilosebaceous system.

Erythromycin inhibits beta2-integrins (CD11b/CD18) expression, interleukin-8 release and intracellular oxidative metabolism in neutrophils

Macrolides have therapeutic benefits on chronic inflammatory airway diseases. Thus, macrolides are supposed to have variable biological effects apart from antimicrobial activity. Neutrophil adherence and influx with oxidants and cytokines production implicates involvement in airway inflammation. To investigate whether erythromycin (EM) affects neutrophil activity in vitro, lipopolysaccharide (LPS)-treated neutrophils were continuously incubated for 4 h in the absence or presence of increasing doses of EM from 1 microg ml(-1) to 100 microg ml(-1) in the last 2 h. Leukocyte adhesion molecules Mac-1 and intracellular H2O2(DCFH) were determined by flowcytometric assay. IL-8 and TNFalpha in supernatant was measured by ELISA method. The expression of Mac-1 and mean intracellular DCF fluorescence intensity (DCFH) of neutrophils significantly increased after stimulation with LPS. Pretreatment with EM significantly decreased LPS induced Mac-1 expression on neutrophils compared with LPS stimulation only. EM alone (100 microg ml(-1)) also decreased Mac-1 expression on neutrophils. EM significantly reduced the LPS-increased DCFH. EM alone (100 microg ml(-1)) also caused a decrease in DCFH. Increasing doses of EM also significantly decreased the IL-8 released by LPS-stimulated neutrophils. In conclusion, EM exerts a direct effect on the neutrophils by downregulating the expression of beta2-integrin on neutrophils, thus leading to a decrease in the intracellular H2O2, as well as the production of IL-8. Our conclusion provides an explanation for the clinical efficacy of erythromycin in neutrophil-mediated airway inflammation.

Reperfusion injury after focal myocardial ischaemia: polymorphonuclear leukocyte activation and its clinical implications

The only way to rescue ischaemic tissue is to re-instate the oxygen supply to the tissue. However reperfusion of the ischaemic area not only oxygenates the tissue but also initiates a cascade of processes, which may in some cases result in temporary dysfunction of the myocardium. In order to devise protective measures, it is essential to understand the mechanisms and the triggers of this reperfusion phenomenon. In this review we will mainly focus on the inflammatory response caused by reperfusion. We will cover the different steps of polymorphonuclear leukocyte activation and will briefly discuss the molecular biology of the receptors involved. The currently used pharmacological medications in acute cardiology will be reviewed and in particular their actions on polymorphonuclear leukocyte activation, adhesion and degranulation. This review is a compilation of the current knowledge in the field and the therapeutic progress in the prevention of reperfusion injury made today.

Oxidative stress in Staphylococcus aureus associated to the cleavage of an isoxazolylnaphthoquinoneimine with antibacterial capacity

Staphylococcus aureus was inhibited by exposure to 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (Q1). This compound was cleavaged in the presence of bacteria and an efflux of isoxazolamine was detected whereas in the S. aureus membrane and cytoplasm was observed an absorption band similar to that of the bencenoid ring. Non-viable bacteria showed intact Q1 intracellularly and in the membrane. Antistaphylococcus effect was associated to Q1 interaction with the respiratory chain, the oxidative metabolites were stimulated; there was cellular injury simultaneous to reduction of antibiotic molecule and efflux of isoxazolamine. The bacteria treated with Q1 increased its oxygen consumption and superoxide anion generation. Superoxide dismutase (SOD) production was stimulated, but it was principally extracellular in S. aureus. Escherichia coli, a species resistant to the antibiotic, did not reduce Q1 and showed lower superoxide anion generation; besides, there was an increase of intracellular SOD with extracellular decrease.

Roxithromycin, clarithromycin, and azithromycin attenuate the injurious effects of bioactive phospholipids on human respiratory epithelium in vitro

The effects of the bioactive phospholipids (PL), platelet-activating factor (PAF), lyso-PAF, and lysophosphatidylcholine (LPC) on the beat frequency and structural integrity of human ciliated respiratory epithelium were studied in vitro, in the presence or absence of polymorphonuclear leukocytes (PMNL), the antimicrobial agents, roxithromycin, clarithromycin, and azithromycin and the antioxidative enzymes catalase and superoxide dismutase (SOD). All three PL caused dose-dependent slowing of ciliary beat frequency (CBF) and epithelial damage (ED) at concentrations > or = 1 microgram/ml, which were unaffected by inclusion of the antimicrobial agents and antioxidative enzymes. When epithelial strips were exposed to the combination of PMNL and PL, there was significant potentiation of ciliary dysfunction and ED, which was ameliorated by pretreatment of the PMNL with the antimicrobial agents or by inclusion of catalase, but not SOD. These results demonstrate that LPC, PAF, and lyso-PAF cause epithelial damage by direct mechanisms which are oxidant-independent, as well as by indirect mechanisms involving phagocyte-derived reactive oxidants. Macrolides and azalide antimicrobial agents may have beneficial effects on airway inflammation in asthma and microbial infections by protecting ciliated epithelium against oxidative damage inflicted by PL-sensitized phagocytes.