During lung inflammatory episodes, ROS and RNS react with unsaturated fatty acids to form nitrated fatty acids (NFAs); subsequently, NFAs could downregulate the expression of CatS and specifically react with Cys25 via an electrophilic S-alkylation, thereby impairing its elastinolytic activity and its ability to promote emphysema under certain circumstances [173]. The gene discussed is PIMREG; the disease is pulmonary emphysema.