Abstract:
Background: Succinate dehydrogenase inhibitors (SDHIs) are active compounds in a
group of fungicides used extensively worldwide particularly to limit the proliferation of
molds on plants and plants products. SDHIs mediate their effect through the inhibition of
the universally preserved mitochondrial succinate dehydrogenase (SDH), which controls
cellular bioenergetics and metabolism, both meticulously regulated for an adapted
inflammatory response. We therefore set out to provide a highly integrated picture
depicting the impact of SDHIs on the inflammatory process.
Aim: In a set of preliminary studies, we assessed in THP-1 (monocytic leukemia cells)
derived human macrophages (TDM) the cytotoxicity of SDHIs namely, bixafen,
fluopyram, boscalid, and cyflumetofen, as well as their specificity towards SDH.
Moreover, we aimed at determining the impact of SDHIs on the pro-inflammatory
cytokines expression profile.
Methods: THP-1 cells will be differentiated into TDM by incubation for 72 hours in the
presence of PMA (Phorbol-12-mysristate13-acetate). Subsequently, cells will be treated
with different concentrations of SDHIs in presence or absence of glucose for 24, 48, 72
hours and their viability will be assessed using Neutral Red assay. The specificity of
SDHIs will be determined by kinetic studies of several mitochondrial enzymes
(Complexes I, II, and the glycerol-3-phosphate dehydrogenase) in the presence of various
SDHIs using THP-1 macrophage homogenates. Finally, the expression level of chosen
pro-inflammatory cytokines/chemokines will be determined using quantitative
polymerase chain reaction (RT-PCR).
All over, this study will allow us to determine the intricate role of the mitochondrial SDH
using SDHI inhibitors on the inflammatory process that is mediated by macrophages.
