8-fold increase at 24-h postinfection). This phenomenon is coupled with decreased cell survival (16% survival in A. salmonicida infection vs. 54% of survival in S. iniae cocultured cells at 24-h postinfection). However, meticulous analysis of TNF-α mRNA transcription patterns reveals that, depending on (1) bacterial type and (2) bacterial viability, Ivacaftor research buy two substantial quantitative differences in TNF-α

transcription levels can be perceived. First, live bacteria constantly induced higher levels of TNF-α1 and TNF-α2 mRNA expression compared with heat-killed bacteria (16±1.8- vs. 4.1±0.5- or 10.4±1.6-fold increase for A. salmonicida, P<0.01, at 24 h; 3.7±0.2- or 6.6±0.8- vs. 2.5±0.4- or 5.2±0.6-fold increase for S. iniae, P<0.01, at 6 h). Secondly, infection with A. salmonicida, whether live or dead, induced higher TNF-α transcription levels than infection with S. iniae (16±1.8-

or 4.1±0.5- to 10.4±1.6- Protein Tyrosine Kinase inhibitor vs. 3.7±0.2- to 6.6±0.8- or 2.5±0.4- to 5.2±0.6-fold increase in TNF-α1 and TNF-α2 transcription levels for live or dead A. salmonicida or S. iniae, respectively; P<0.05 for live bacteria throughout the experiment and P<0.01 for dead bacteria at 9 h). LPS (positive control) stimulation of RTS11 macrophages gave rise to a time-dependent increase of TNF-α transcription levels (5.2±0.8- to 5.7±0.6-fold increase for TNF-α1 and TNF-α2, peaking at 9 h; P<0.001) that resembles bacterial stimulation (Fig. 2). No differences in cytokine expression levels were recorded following PBS stimulation. The overall similarity (both from the kinetic and the quantitative aspects) in the increase of TNF-α transcription patterns following LPS stimulation and the coculture of RTS11 trout macrophages with specific pathogens strengthens the reliability of the experimental model. This is further demonstrated by an additional control, consisting of coculture of RTS11 macrophages with live or killed mafosfamide S. caseolyticus KFP 776, a commensal

Gram-positive strain recovered from the skin of a healthy rainbow trout. Staphylococcus caseolyticus induced only a minimal increase in TNF-α1 transcription levels (1.4±0.3- or 1.7±0.2-fold increase after coculture with dead or live bacteria, respectively); induction of TNF-α2 transcription (3.6±0.5- or 4.5±0.6-fold increase after coculture with dead or live bacteria, respectively) was also lower than that of A. salmonicida or S. iniae (P<0.01 for both). The amplitude of IL-1 mRNA transcription levels in RTS11 macrophages stimulated by killed S. iniae cells closely resembled that of the same cells cocultured with LPS or A. salmonicida-positive controls (4.5±0.6, 5.4±0.7 SD and 5.3±0.3-fold increase, respectively; all peaking at 9-h postinfection) (Fig. 1). Interestingly, live S. iniae were found to be poor stimulants of IL-1 mRNA transcription, and the (apparent biwave) rise in IL-1 mRNA transcription levels is notably lower than what was observed with other stimulators (P<0.