Kinetic Redox Shotgun Proteomics Reveals Specific Lipopolysaccharide Effects on Intestinal Epithelial Cells, Mitigated by a Mn Superoxide Dismutase Mimic

Abstract Overproduction of reactive oxygen species and antioxidant superoxide dismutases (SOD1, SOD2) dysregulation contribute to chronic inflammation such as generated in inflammatory bowel diseases (IBD). A kinetic redox shotgun proteomic strategy (OcSILAC for Oxidized cysteine Stable Isotope Labelling by Amino acids in Cell culture) was used to explore the lipopolysaccharide (LPS) effects including LPS‐induced oxidation and inflammation cascades on a dedicated intestinal epithelial cell line (HT29‐MD2) together with the potential mitigating role of a Mn‐based SOD‐mimic Mn1 . While LPS induced transient oxidative damages at early times (15 min), cells incubated with Mn1 showed, in this time frame, a significantly reduced cysteine oxidation, highlighting Mn1 antioxidant properties. Over time, cysteine oxidation of LPS‐treated cells was counteracted by an overexpression of antioxidant proteins (SOD1, NQO1) and a late (6 h) preponderant increase in SOD2 level. Mn1 , when co‐incubated with LPS, attenuated the level of most LPS‐modified proteins, that is, proteins involved in the inflammatory response. Our results highlight Mn1 as a potentially effective antioxidant and anti‐inflammatory agent to consider in the treatment of IBD, as well as a useful tool for exploring the interconnection between oxidative stress and inflammation.