**5. Conclusions**

SLE is a chronic autoimmune disease with complex pathogenesis, characterized by oxidative stress and high inflammatory state. The cellular response to oxidative stimuli in this pathology is concreted in the amplification of oxidative degradation of lipids, proteins, nucleic acid, and hydro carbonates, and in alteration of endogenous strategies for suppressing/modulating oxidative stress. The defective DNA repair mechanism via OGG1, the reduced regulatory effect of sRAGE in the activation of AGE-RAGE axis, low levels of thiols, disulphide bonds formation and high nitrotyrosination are important characteristics of lupus nephritis in our study and they could explain alteration of renal architecture and development of renal injury in SLE. All these data help us to establish a panel of biomarkers in order to identify as early as possible the patients at risk for LN development, thus avoiding invasive interventions such as renal biopsy, and establishing an effective treatment as soon as possible from diagnosis. The identification of more molecular mechanisms to counteract oxidative stress in LN could permit a more precise assessment of disease prognosis, as well as the development of new therapeutic targets.

**Author Contributions:** All authors have equally contributed to the writing and editing of the manuscript. Conceptualization, C.D.E., and I.N.; methodology, I.N.; software, C.D.E.; validation, C.D.E., I.N., S.R.G., and M.N.P.; formal analysis, I.N.; investigation, C.D.E.; resources, M.T., S.R.G., C.M.; data curation, C.D.E., S.R.G.; writing—original draft preparation, C.D.E., C.I.M., M.I.M.; writing—review and editing, C.D.E., M.N.P., C.M., M.T.; visualization, S.R.G., C.I.M., M.I.M., C.M.; supervision, S.R.G., I.N., M.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of Clinical Hospital of Nephrology "Carol Davila" (11/23.07.2018).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest.
