Cytotoxic effects of four antibiotics on endothelial cells

Antibacterial Anacardic Acid Derivatives

We report on the antibacterial activity of five phenolic lipids derived from anacardic acid characterized by increasing alkyl chain lengths with 6, 8, 10, 12, or 14 carbon atoms. The compounds were profiled for their physicochemical properties, transport across epithelial monolayers, cytotoxicity, and antibacterial activity as compared to common antibiotics. No cytotoxicity was reported in cell lines of fibroblast, hepatic, colorectal, or renal origin. C₁₀ and C₁₂ significantly increased the survival in a Galleria mellonella model infected with multi-drug-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococci (VRE) as compared to the untreated control group. Future studies are required to corroborate these findings in relevant animal model systems of infection.

Vascular Cells and Tissue Constructs Derived from Human Pluripotent Stem Cells for Toxicological Screening

The ability of human stem cells to generate somatic cell lineages makes them ideal candidates for use in toxicological testing and eventually, preclinical drug development. Such resources would support an evolution away from human primary cells or research animal models, which suffer from variability and poor predictability, toward off-the-shelf assays of chemical toxicity and drug efficacy using human cells and tissues. To this end, we generated vascular cell populations (smooth muscle cells and endothelial cells) from human pluripotent stem cells (hPSCs), arranged them into 3D co-cultures within supportive gel matrices, and directed their propensity for self-organization resembling microvasculature. The resulting vascular cell populations and co-cultured constructs were then arrayed in high throughput and used for screening a library of environmental and clinical chemical agents for immunological and toxicological responses. The screen effectively stratified the chemicals into various levels of toxicity, with both cell type-specific and co-culture-dependent responses observed. Thus, hPSC-derived vascular cells and constructs could be progressed further toward use in toxicant and drug screening.

Preparation and antibacterial behaviour of nanostructured Ag@SiO2–penicillin with silver nanoplates

Preparation of Ag@SiO₂–penicillin NPs with superior synergistic and antibacterial properties against methicillin-resistant Staphylococcus aureus.

Endothelial Cell Toxicity of Vancomycin Infusion Combined with Other Antibiotics

French guidelines recommend central intravenous (i.v.) infusion for high concentrations of vancomycin, but peripheral intravenous (p.i.v.) infusion is often preferred in intensive care units. Vancomycin infusion has been implicated in cases of phlebitis, with endothelial toxicity depending on the drug concentration and the duration of the infusion. Vancomycin is frequently infused in combination with other i.v. antibiotics through the same administrative Y site, but the local toxicity of such combinations has been poorly evaluated. Such an assessment could improve vancomycin infusion procedures in hospitals. Human umbilical vein endothelial cells (HUVEC) were challenged with clinical doses of vancomycin over 24 h with or without other i.v. antibiotics. Cell death was measured with the alamarBlue test. We observed an excess cellular death rate without any synergistic effect but dependent on the numbers of combined infusions when vancomycin and erythromycin or gentamicin were infused through the same Y site. Incompatibility between vancomycin and piperacillin-tazobactam was not observed in our study, and rinsing the cells between the two antibiotic infusions did not reduce endothelial toxicity. No endothelial toxicity of imipenem-cilastatin was observed when combined with vancomycin. p.i.v. vancomycin infusion in combination with other medications requires new recommendations to prevent phlebitis, including limiting coinfusion on the same line, reducing the infusion rate, and choosing an intermittent infusion method. Further studies need to be carried out to explore other drug combinations in long-term vancomycin p.i.v. therapy so as to gain insight into the mechanisms of drug incompatibility under multidrug infusion conditions.

Do surface active parenteral formulations cause inflammation?

Local irritation and inflammation at the site of administration are a common side effect following administration of parenteral formulations. Biological effects of surface (interfacial) activity in solutions are less well investigated than effects caused by other physico-chemical parameters such as pH and osmolality. The interfacial activity in different systems, including human plasma, typical amphiphilic substances with fundamental biological relevance such as free fatty acids, anesthetic depot formulations and six different antibiotics was measured. The relative interfacial pressure, and/or concentration of active substance, required to obtain 50% of the maximal attainable effect in terms of interfacial pressure were calculated. The aim was to test the hypothesis that these parameters would allow comparison to biological effects reported in in vivo studies on the investigated substances. The highest interfacial activity was found in a triglyceride/plasma system. Among the antibiotic tested, the highest interfacial activities were found in erythromycin and dicloxacillin, which is in accordance with previous clinical findings of a high tendency of infusion phlebitis and cell toxicity. Independently of investigated system, biological effects were minimal below a 15% relative increase of interfacial activity. Above 35-45% the effects were severe. Interfacial activity in parenteral formulations may well cause damages to tissues followed by inflammation.

The antibiotic erythromycin did not affect micronucleus frequency in human PHA-stimulated lymphocytes

The aim of the present study was to investigate the ability of the antibiotic erythromycin to induce micro?nucleus (MN) frequency and the cytokinesis block proliferation index (CBPI) in human peripheral blood lymphocytes in vitro using the cytokinesis-block micronucleus test (CBMN). Cell cultures were treated with five different concentrations of erythromycin ranging from 0.68 x 10-4 to 5.45 x 10-4 M. The positive control cells were treated with a known mutagen, mitomycin C (MMC), in a concentration of 1.6 x 10-6 M. None of the tested concentrations of erythromycin significantly changed the average MN frequency or CBPI in PHA-stimulated lymphocytes (p > 0.05).

Effect of quinupristin/dalfopristin on 3T3 and Eahy926 cells in vitro in comparison to other antimicrobial agents with the potential to induce infusion phlebitis

Infusion phlebitis is a common clinical problem that is observed with some antimicrobial agents, when being administered intravenously. In this study, cultured murine fibroblasts and immortalised human endothelial cells were exposed to three antibiotics at clinically relevant concentrations to assess their toxic potential in two established cytotoxicity assays. BALB/c 3T3 fibroblasts and Eahy926 endothelial cells were exposed to quinupristin/dalfopristin (QD), erythromycin and levofloxacin at increasing concentrations. For assessment of cytotoxicity the cells were incubated with neutral red (NR) or stained with crystal violet (CV). Measurements were done by photometry. At the concentration range tested QD and erythromycin showed a concentration-dependent cytotoxic effect in both cell cultures. In 3T3 cells the half-maximal effect concentration (EC50) was 20 mg/l for QD and 340 mg/l for erythromycin in the NR uptake test and 12 and 200 mg/l, respectively, in the CV assay. In Eahy926 cells the EC50 was 50 mg/l for QD and 880 mg/l for erythromycin in the NR uptake test and 40 and 750 mg/l, respectively, in the CV assay. No EC50 could be established in both cell types for levofloxacin. Eahy926 cells were less sensitive to cytotoxic stimuli than 3T3 fibroblasts. Cytotoxic effects in both cell cultures occurred in the following order: QD > erythromycin >> levofloxacin. This ranking correlates well with the frequency of local adverse effects observed with the infusion of these antibiotics in patients. Thus, these in vitro assays may serve as an estimate for the prediction of local tolerability of antibiotics when administered parenterally.

Cell death effects of resin-based dental material compounds and mercurials in human gingival fibroblasts

In order to test the hypothesis that released dental restorative materials can reach toxic levels in human oral tissues, the cytotoxicities of the resin-based dental (co)monomers hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (BisGMA) compared with methyl mercury chloride (MeHgCl) and the amalgam component mercuric chloride (HgCl2) were investigated on human gingival fibroblasts (HGF) using two different test systems: (1) the modified XTT-test and (2) the modified H 33342 staining assay. The HGF were exposed to various concentrations of the test-substances in all test systems for 24 h. All tested (co)monomers and mercury compounds significantly (P<0.05) decreased the formazan formation in the XTT-test. EC50 values in the XTT assay were obtained as half-maximum-effect concentrations from fitted curves. Following EC50 values were found (mean [mmol/l]; s.e.m. in parentheses; n=12; * significantly different to HEMA): HEMA 11.530 (0.600); TEGDMA* 3.460 (0.200); UDMA* 0.106 (0.005); BisGMA* 0.087 (0.001); HgCl2* 0.013 (0.001); MeHgCl* 0.005 (0.001). Following relative toxicities were found: HEMA 1; TEGDMA 3; UDMA 109; BisGMA 133; HgCl2 887; MeHgCl 2306. A significant (P<0.05) increase of the toxicity of (co)monomers and mercurials was found in the XTT-test in the following order: HEMA < TEGDMA < UDMA < BisGMA < HgCl2 < MeHgCl. TEGDMA and MeHgCl induced mainly apoptotic cell death. HEMA, UDMA, BisGMA, and HgCl2 induced mainly necrotic cell death. The results of this study indicate that resin composite components have a lower toxicity than mercury from amalgam in HGF. HEMA, BisGMA, UDMA, and HgCl2 induced mainly necrosis, but it is rather unlikely that eluted substances (solely) can reach concentrations, which might induce necrotic cell death in the human physiological situation, indicating that other (additional) factors may be involved in the induction of tissue (pulp) inflammation effects after dental restauration.

Antibiotics differ in their tendency to cause infusion phlebitis: a prospective observational study

Intravenous administration of antibiotics is a known risk factor for infusion phlebitis. We have previously demonstrated differences in cell toxicity for 4 antibiotics. Clinical experience indicates that antibiotics differ in their tendency to cause phlebitis. The present study was done prospectively on 550 patients with 1386 peripheral venous catheters. The incidence of phlebitis was 18.5% with antibiotics and 8.8% without (odds ratio 2.34). Dicloxacillin (odds ratio 5.74) and erythromycin (odds ratio 5.33) had the greatest tendency to cause phlebitis in univariate, multivariate and Cox regression analyses. Benzylpenicillin, cefuroxime and cloxacillin were also associated with a greater risk of phlebitis, whereas ampicillin, imipenem/cilastatin, clindamycin, netilmicin and vancomycin were not. Other risk factors were the site of insertion and age 51-60 y. Medication with warfarin was found to be protective, but not with aspirin. Treatment with low molecular weight heparin reduced the risk of phlebitis, but the difference was not significant. With regard to when antibiotics were given, the day-specific risk increased between Days 1 and 2, but no further on subsequent days. The hypothesis that antibiotics differ in their tendency to cause phlebitis was confirmed.

Mechanisms underlying chlorhexidine-induced cytotoxicity

Chlorhexidine (CLX) is the most widely used antiseptic for wound and skin disinfection. Despite its potent bactericidal action, skin irritation is observed when it is used topically. This study aimed to evaluate the mechanisms underlying CLX-induced toxicity on human dermal fibroblasts with special emphasis on factors that may mediate or counteract its undesirable effects. Cells were exposed to CLX concentrations of 0.00005-0.025% for 3, 6, 8 or 24 h in the absence or presence of different concentrations of foetal calf serum (FCS) (2, 5 and 10%). Depletion of cell ATP occurred, in a time- and concentration-dependent manner, in all experimental conditions at [CLX] >0.001%. At 24 h of CLX exposure time, the decrease in intracellular ATP was produced from a 10-times lower CLX concentration (0.0001%). Concentrations > or =0.02% produced total loss of ATP. However, cell survival was maintained after CLX treatment for 3 and 8 h and CLX concentrations > or =0.005% were required to produce total cell death. CLX exerted an inhibitory concentration-dependent effect on DNA synthesis from concentrations as low as 0.0001%. Only FCS at 10% appeared to have a cytoprotective action against CLX-induced cytotoxicity.

Effect of erythromycin on matrix metalloproteinase-9 and cell migration

Erythromycin (EM) has an anti-inflammatory effect that may account for its clinical benefit in the treatment of chronic inflammatory diseases such as diffuse panbronchiolitis. To investigate the mechanism of this anti-inflammatory effect, we studied the relationship between the concentration of EM and matrix metalloproteinase-9 (MMP-9) activity, which is important in cell migration. We showed that EM suppressed the gelatinolytic activity of U937 cell-derived MMP-9 by using gelatin zymography, showed that expressions of MMP-9 protein and MMP-9 mRNA were down-regulated by EM in a dose-dependent manner, and showed that U937 migration was also suppressed by EM. We also demonstrated that EM treatment suppressed the gelatinolytic activity of MMP-9 in spleen macrophages. These findings suggest that the suppressive effect of EM on MMP-9 activity is one of the anti-inflammatory mechanisms that inhibit the migration of inflammatory cells into the inflammatory site.