title: Nitric oxide-mediated augmentation of neutrophil reactive oxygen and nitrogen species formation: Critical use of probes.
abstract: Previous reports from this laboratory and others demonstrated NO-mediated biphasic modulation of NADPH oxidase and attenuation of neutrophil reactive oxygen species generation, whereas recently we reported augmentation in DCF fluorescence following NO treatment. These discrepancies seem to be due to utilization of different probes/methods to assess effect of NO on reactive oxygen and nitrogen species (ROS/RNS, reactive species) generation. This study aims to look into this and evaluate NO-mediated enzymatic reactive species formation by using multiple probes, human neutrophils/HL60 cells and various interventions. Addition of NO donor, SNP or SNAP (100 nM-1 mM) to PMNs suspension, exhibited a concentration- and time-dependent augmentation in DCF fluorescence, but reduced DHE fluorescence. Collective generation of reactive species was confirmed by enhanced DMPO-nitrone adduct, dityrosine and rhodamine-123 and quenching of scopoletin. NO also enhanced bacterial killing, without altering phagocytosis. Addition of NO to HL-60 cells lacking functional NADPH oxidase enhanced reactive species formation, indicating importance of other enzyme(s) too. NO-dependent ROS/RNS generation was substantially reduced by NADPH oxidase inhibitor (DPI), MPO inhibitor (ABAH), or NOS inhibitor (7-NI). However, 7-NI reduced MPO activity, warranting reappraisal of those reports, which implied NOS in reactive species formation. The results obtained demonstrated NO-mediated reactive species augmentation in human PMNs. Furthermore, superoxide scavenging by NO seems to be the key process in the decrease of DHE fluorescence and suggest usefulness of DCF as the most appropriate probe to measure the NO-mediated modulation of reactive oxygen species in particular in various pathological situations.
authors.affiliation: Pharmacology Division, Central Drug Research Institute (Council of Scientific and Industrial Research), Lucknow, India.
authors.forename: Sachin
authors.initials: S
authors.lastname: Kumar
authors.forename: Satyananda
authors.initials: S
authors.lastname: Patel
authors.forename: Anupam
authors.initials: A
authors.lastname: Jyoti
authors.forename: Ravi Shankar
authors.initials: RS
authors.lastname: Keshari
authors.forename: Anupam
authors.initials: A
authors.lastname: Verma
authors.forename: Manoj Kumar
authors.initials: MK
authors.lastname: Barthwal
authors.forename: Madhu
authors.initials: M
authors.lastname: Dikshit
mesh_terms: D004359:Drug Therapy, Combination; D005434:Flow Cytometry / Q000379:methods*; D005452:Fluoresceins / Q000737:chemistry; D005453:Fluorescence; D018922:HL-60 Cells; D006801:Humans; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010587:Phagocytosis / Q000187:drug effects; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology
chemical_list: C110400:2',7'-dichlorodihydrofluorescein diacetate; D005452:Fluoresceins; D020030:Nitric Oxide Donors; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D009599:Nitroprusside; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine