Effect of beta-lactam antibiotics on a human myeloid cell line: investigation of potential in vivo correlates in the mouse

Unraveling Hematotoxicity of α-Amanitin in Cultured Hematopoietic Cells

Amanita phalloides poisonings account for the majority of fatal mushroom poisonings. Recently, we identified hematotoxicity as a relevant aspect of Amanita poisonings. In this study, we investigated the effects of the main toxins of Amanita phalloides, α- and β-amanitin, on hematopoietic cell viability in vitro. Hematopoietic cell lines were exposed to α-amanitin or β-amanitin for up to 72 h with or without the pan-caspase inhibitor Z-VAD(OH)-FMK, antidotes N-acetylcysteine, silibinin, and benzylpenicillin, and organic anion-transporting polypeptide 1B3 (OATP1B3) inhibitors rifampicin and cyclosporin. Cell viability was established by trypan blue exclusion, annexin V staining, and a MTS assay. Caspase-3/7 activity was determined with Caspase-Glo assay, and cleaved caspase-3 was quantified by Western analysis. Cell number and colony-forming units were quantified after exposure to α-amanitin in primary CD34+ hematopoietic stem cells. In all cell lines, α-amanitin concentration-dependently decreased viability and mitochondrial activity. β-Amanitin was less toxic, but still significantly reduced viability. α-Amanitin increased caspase-3/7 activity by 2.8-fold and cleaved caspase-3 by 2.3-fold. Z-VAD(OH)-FMK significantly reduced α-amanitin-induced toxicity. In CD34+ stem cells, α-amanitin decreased the number of colonies and cells. The antidotes and OATP1B3 inhibitors did not reverse α-amanitin-induced toxicity. In conclusion, α-amanitin induces apoptosis in hematopoietic cells via a caspase-dependent mechanism.

Evolving Role of Pharmacogenetic Biomarkers to Predict Drug-Induced Hematological Disorders

ABSTRACT

Drug-induced hematological disorders constitute up to 30% of all blood dyscrasias seen in the clinic. Hematologic toxicity from drugs may range from life-threatening marrow aplasia, agranulocytosis, hemolysis, thrombosis to mild leukopenia, and thrombocytopenia. Pathophysiologic mechanisms underlying these disorders vary from an extension of the pharmacological effect of the drug to idiosyncratic and immune-mediated reactions. Predicting these reactions is often difficult, and this makes clinical decision-making challenging. Evidence supporting the role of pharmacogenomics in the management of these disorders in clinical practice is rapidly evolving. Despite the Clinical Pharmacology Implementation Consortium and Pharmacogenomics Knowledge Base recommendations, few tests have been incorporated into routine practice. This review aims to provide a comprehensive summary of the various drugs which are implicated for the hematological adverse events, their underlying mechanisms, and the current evidence and practical recommendations to incorporate pharmacogenomic testing in clinical care for predicting these disorders.

Selective toxicity of antibacterial agents-still a valid concept or do we miss chances and ignore risks?

BACKGROUND

Selective toxicity antibacteribiotics is considered to be due to interactions with targets either being unique to bacteria or being characterized by a dichotomy between pro- and eukaryotic pathways with high affinities of agents to bacterial- rather than eukaryotic targets. However, the theory of selective toxicity oversimplifies the complex modes of action of antibiotics in pro- and eukaryotes.

METHODS AND OBJECTIVE

This review summarizes data describing multiple modes of action of antibiotics in eukaryotes.

RESULTS

Aminoglycosides, macrolides, oxazolidinones, chloramphenicol, clindamycin, tetracyclines, glycylcyclines, fluoroquinolones, rifampicin, bedaquillin, ß-lactams inhibited mitochondrial translation either due to binding to mitosomes, inhibition of mitochondrial RNA-polymerase-, topoisomerase 2ß-, ATP-synthesis, transporter activities. Oxazolidinones, tetracyclines, vancomycin, ß-lactams, bacitracin, isoniazid, nitroxoline inhibited matrix-metalloproteinases (MMP) due to chelation with zinc and calcium, whereas fluoroquinols fluoroquinolones and chloramphenicol chelated with these cations, too, but increased MMP activities. MMP-inhibition supported clinical efficacies of ß-lactams and daptomycin in skin-infections, and of macrolides, tetracyclines in respiratory-diseases. Chelation may have contributed to neuroprotection by ß-lactams and fluoroquinolones. Aminoglycosides, macrolides, chloramphenicol, oxazolidins oxazolidinones, tetracyclines caused read-through of premature stop codons. Several additional targets for antibiotics in human cells have been identified like interaction of fluoroquinolones with DNA damage repair in eukaryotes, or inhibition of mucin overproduction by oxazolidinones.

CONCLUSION

The effects of antibiotics on eukaryotes are due to identical mechanisms as their antibacterial activities because of structural and functional homologies of pro- and eukaryotic targets, so that the effects of antibiotics on mammals are integral parts of their overall mechanisms of action.

Comparison of Neutropenia Associated with Ceftaroline or Ceftriaxone in Patients Receiving at Least 7 Days of Therapy for Severe Infections

STUDY OBJECTIVE

Ceftarolinefosamil is a cephalosporin with broad clinical utility; however, limited data suggest that prolonged ceftaroline exposure may be associated with neutropenia. The objective was to determine drug and patient factors associated with neutropenia in patients receiving ceftaroline or ceftriaxone for deep-seated infections.

DESIGN

Retrospective, ratio-matched cohort study.

SETTING

Four acute-care hospitals within an urban health care system.

PATIENTS

A total of 176 hospitalized adults who received definitive ceftaroline (44 patients) or ceftriaxone (132 patients) therapy for at least 7 days between January 2013 and April 2017 for any of the following indications: bone and joint infections (BJI), infective endocarditis (IE), or bloodstream infections (BSI).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was development of neutropenia while receiving cephalosporin therapy, defined as an absolute neutrophil count (ANC) <1500 cells/mm3 . Neutropenia severity and patient characteristics were described and compared between the ceftaroline and ceftriaxone groups. The median (interquartile range [IQR]) antibiotic prescription duration was 41 (29-44) days for the ceftaroline group and 40 (28-44) days for the ceftriaxone group (p=0.9). Cephalosporin indications were 112 (64%) BJI, 27 (15%) BSI, 16 (9%) IE, and 21 (12%) multiple infections; ceftaroline was more commonly used in BJI (p=0.03), and ceftriaxone was more commonly used in IE (p=0.01). Neutropenia developed in 16 (9%) patients: 8 (18%) in the ceftaroline group and 8 (6%) in the ceftriaxone group (p=0.03). Median (IQR) onset to neutropenia was 22 (15-28) days, and median (IQR) change in ANC was 2.86 (1.50-4.08) cells/mm3 ; most cases of neutropenia were mild (12 patients [75%]). The median (IQR) time to mild or moderate-severe neutropenia was not significantly different (p=0.68): 22 (14-28) and 22 (21-36) days, respectively. Treatment was discontinued in 4 (25%) patients due to neutropenia. Ceftaroline use was independently associated with neutropenia (adjusted odds ratio 3.2, 95% confidence interval 1.2-10.5) after adjusting for lower body mass index strata (18.5-25 kg/m2 ).

CONCLUSION

Prolonged ceftaroline use was an independent risk factor for developing mild neutropenia. Clinicians should be cognizant of ANC monitoring in scenarios where prolonged ceftaroline courses are prescribed.

Pharmacokinetics and pharmacogenomics of β-lactam-induced neutropenia

AIM

Determine if individuals with β-lactam induced neutropenia have polymorphisms that impair function of MRP4 or OAT1/OAT3.

METHODS

Subjects with β-lactam induced neutropenia were compared to controls for the presence of MRP4 and OAT1/OAT3 polymorphisms, estimated plasma trough concentrations and area under the curve.

RESULTS

Subjects with a homozygous polymorphism at MRP4 3348 A to G were 5.3 times more likely to develop neutropenia (p = 0.171). No statistical differences were noted in pharmacokinetic parameters. Contingency analysis of children greater than 5 years of age showed neutropenia in subjects who were homozygous wild type at MRP4 3348 A to G was significantly associated with standard or high dosing (p = 0.03).

CONCLUSION

MRP4 3348 A to G should be further studied for potential contribution to the development of β-lactam induced neutropenia.

Effects of ceftazidime, a betalactam antibiotic, on murine haemopoiesis in vitro

Agranulocytosis has been reported in 5-15% of patients treated with high-dose betalactam antibiotics (BLA). We investigated the toxic effect of ceftazidime (CEF) as a representative of these antibiotics on colony-forming unit-granulocyte/macrophage (CFU-GM), on burst-forming unit-erythroid (BFU-E) colony growth and on myelopoiesis in murine long-term bone marrow culture (mLTBMC). The CEF concentration resulting in a 50% inhibition of growth was 146 micrograms/ml (267 microM) for CFU-GM, 132 micrograms/ml (241 microM) for BFU-E and 180 micrograms/ml (329 microM) for myeloid cell production in the supernatant of mLTBMC. Following addition of CEF to mLTBMC, CFU-GM remained low for 1 week and total myeloid cell production remained low for 2 weeks after removal of CEF from culture. Thereafter the values returned to control levels. The myeloid differential counts in the supernatant and adherent layers demonstrated a 'maturation arrest', which could be overcome by simultaneously adding all-trans retinoic acid to culture. These results demonstrate that CEF has reversible inhibitory effects on myelopoiesis and highlight the utility of in vitro haemopoietic assays as models to examine drug-induced haemopoietic dyscrasias.

Effects of beta-lactam antibiotics on eukaryotic cells

A symposium on effects of beta-lactam antibiotics on eukaryotic cells was held as part of the 9th International Congress of Infectious and Parasitic Diseases (Munich, Germany, July 1986). This symposium provided an opportunity to review recent work on the effect of beta-lactam structures on mammalian cells in culture and to speculate on possible clinical implications. This paper is a comment on the subject matter covered by the symposium papers which follow.