Fluoroquinolone antibiotics have been known to cause severe, multisystem adverse side effects, termed fluoroquinolone toxicity (FQT). This toxicity syndrome can present with adverse effects that vary from individual to individual, including effects on the musculoskeletal and nervous systems, among others. The mechanism behind FQT in mammals is not known, although various possibilities have been investigated. Among the hypothesized FQT mechanisms, those that could potentially explain multisystem toxicity include off-target mammalian topoisomerase interactions, increased production of reactive oxygen species, oxidative stress, and oxidative damage, as well as metal chelating properties of FQs. This review presents relevant information on fluoroquinolone antibiotics and FQT and explores the mechanisms that have been proposed. A fluoroquinolone-induced increase in reactive oxygen species and subsequent oxidative stress and damage presents the strongest evidence to explain this multisystem toxicity syndrome. Understanding the mechanism of FQT in mammals is important to aid in the prevention and treatment of this condition.
Cells have mechanisms in place to maintain the specific lipid composition of distinct organelles including vesicular transport by the endomembrane system and non-vesicular lipid transport by lipid transport proteins. Oxysterol Binding Proteins (OSBPs) are a family of lipid transport proteins that transfer lipids at various membrane contact sites (MCSs). OSBPs have been extensively investigated in human and yeast cells where twelve have been identified in Homo sapiens and seven in Saccharomyces cerevisiae. The evolutionary relationship between these well-characterized OSBPs is still unclear. Reconstructed OSBP phylogenies revealed that the ancestral Saccharomycotinan had four OSBPs, the ancestral Holomycotan had five OSBPs, the ancestral Holozoan had six OSBPs, the ancestral Opisthokont had three OSBPs, and the ancestral Eukaroyte had three OSBPs. Our analysis identified three clades of ancient OSBPs not present in animals or fungi.