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