This suspension was then incubated at 70 °C for 60 min. Inactivation efficiency was checked after an overnight incubation of aliquots plated on blood agar plates. For cell infection assays, the E. coli pyelonephritis strain CFT073 was used. Bacteria were grown on blood agar plates and prepared

in PBS as described above and then added to cells at a final concentration of 106 CFU mL−1. The nonerythropoietic Epo analogue ARA290 was synthesized as described previously. Stock solutions (1–100 μM) were prepared in PBS, filter sterilized (0.2 μm) and kept at 4 °C for up to 4 weeks. Experiments were performed in 24-well cell culture plates (Costar, Corning, NY). Inactivated bacteria were added to the medium at a final inoculum equivalent to 104, 106 and 108 CFU mL−1 Pexidartinib selleck inhibitor for the initial dose–response experiments. Following this, an inoculum of 106 CFU mL−1 was used. Bacteria were used either alone or together with ARA290 at indicated concentrations (10–1000 nM). As a control, an equal volume of PBS was added to the medium without ARA290. Cells were stimulated for 1–24 h at 37 °C in a 5% CO2

and humidified atmosphere. Cells were stimulated with gentamicin-inactivated E. coli NU14 as described above. Cells were collected before stimulation and after 1, 3, 6, 12 and 24 h. Total RNA was extracted using the RNeasy Mini Kit (Qiagen, Hamburg, Germany) according to the manufacturer’s recommendations. RNA was stored at −80 °C until further use. An aliquot of <1 μg was transcribed to cDNA using the DyNAmo cDNA Synthesis kit (Finnzymes, Espoo, Finland). The expression

of IL-8, EpoR, LL-37 and β1-integrin was analyzed using gene-specific TaqMan Gene Expression Assays (Applied Biosystems, Carlsbad, CA) according to the manufacturer’s instructions. The location of the probes in all assays excluded CYTH4 the detection of genomic DNA. The relative expression of the genes was determined using the ΔΔCT method with GAPDH as an endogenous control (Applied Biosystems). Supernatants from cells stimulated as described for RNA isolation were collected, centrifuged at 300 g for 10 min at 4 °C to remove detached cells and stored at −20 °C until analysis. Aliquots in appropriate dilutions were analyzed for IL-8 protein levels by enzyme-linked immunosorbent assay (ELISA) using the DuoSet ELISA Development System as described by the manufacturer (R&D Systems, Abingdon, UK). Confluent cells in 24-well plates were stimulated with heat-inactivated E. coli NU14 with or without ARA290 in different concentrations. Each condition was analyzed in triplicate. After 6 h of stimulation, E. coli CFT073 was added to each well at a final concentration of 106 CFU mL−1. Plates were centrifuged at 300 g for 5 min to expedite bacterial contact with host cells and then incubated for 30 min at 37 °C.