Fig 1.

(a) Fold change in NETosis triggered by either methicillin-resistant Staphylococcus aureus (MRSA; stationary phase, MOI 10, n=4) or phorbol myristate acetate (PMA; 25 nM, n=5) in the presence of increasing concentrations of dexmedetomidine. NET production (extracellular DNA) was quantified using PicoGreen dye. (b) Immunocytochemical analysis of NETosis in response to PMA (25 nM) in the presence or absence of 5 ng/mL (25 nM) dexmedetomidine. Green: myeloperoxidase (staining NETs); blue: DAPI (staining nuclei). (c) Time course of reactive oxygen species (ROS) production by human neutrophils (measured at indicated time points using H₂DCFDA, n=3) in the presence or absence of dexmedetomidine either alone or with PMA. (d) Chemotaxis of human neutrophils in response to 100 nM N-formylmethionyl-leucyl phenylalanine (fMLP) in the presence or absence of several concentrations of dexmedetomidine (assessed using Transwell inserts with a 3 μm pore size as described previously, n=5). (e) Phagocytosis time course of S. aureus bioparticles in the presence and absence of several concentrations of dexmedetomidine, n=4. (f) MRSA killing by human neutrophils (MOI 10) in the presence of dexmedetomidine at 5 ng/mL (25 nM) and dexmedetomidine and yohimbine at indicated concentration as compared with the respective control without cells expressed as % colony-forming units (CFU) ml⁻¹, n=8. (g) MRSA killing by human neutrophils (MOI 10) in the presence of several concentrations of yohimbine as compared with the respective control without cells expressed as % CFU ml⁻¹, n=3. (h) amount of MRSA per g of either liver or kidney tissue after an 24 h in vivo intraperitoneal (i.p.) challenge of CD-1 mice that received either dexmedetomidine or phosphate-buffered saline (PBS) i.p. at time of infection and 1 h after infection, n=24, 12 in each group. One-way analysis of variance with post hoc analysis was used to assess significance for data shown here, with the exception of the MRSA i.p. challenge, where unpaired Student's t-test was used. ∗P<0.05; ∗∗P<0.01. CTL, control; DEX, dexmedetomidine; H₂DCFDA, 2′,7′-dichlorodihydrofluorescein diacetate; NETOsis, neutrophil extracellular trap formation; NETs, neutrophil extracellular traps; n.s., not significant; YOH, yohimbine.