Lipi peroxidation in autoimmune diseases: Friend or foe?

Auto immune diseases (AIDs) comprise over 80 different disorders that affect 1-2% of the world population. AIDs are triggered by genetic, environmental and metabolic factors affecting mucous, gastric, cutaneous, neuronal, connective, lung, bone and other tissues. The reported low antioxidant levels in autoimmune diseases suggest a redox imbalance and evidence that oxidative stress and oxidative modifications to biomolecules generating neoepitopes triggering an exacerbated inflammatory response and a major role in pathophysiology of these diseases. Increased carbonyl content and lipid hydroperoxides quantified in biological fluids evidences for an active role of lipid peroxidation in the onset and progression of autoimmune diseases. Lipid peroxidation is a very complex chain reaction that generates an overwhelming array of lipid peroxidation products (LPP) with epitopes recognized by the immune system and able to modulate the immune response. Given the complexity of the LPP likely to be formed, their accurate identification and quantification in the various biological fluids is challenging. This chapter describes the current knowledge on LPP identified in AIDs, their levels in fluids, cells and tissues, and methodological approaches applied for their detection and quantification. An overview on the advantages and limitations associated with the identification and quantification using specific and unspecific strategies will also be provided. Based on the findings, we describe their role in the onset and resolution of immune response and the validity of lipid peroxidation products (LPP) as potential AIDs biomarkers for early diagnosis and monitoring disease status.