Could Skin Autofluorescence Be a Useful Biomarker in Systemic Lupus Erythematosus? A Systematic Review.

Systemic lupus erythematosus (SLE) is a multifaceted autoimmune disease with a heterogeneous organ involvement, for which reliable biomarkers are still being studied. The implication of advanced glycation end products (AGEs), resulting from oxidative stress, and their interaction with the receptor for AGEs (RAGE) has been studied in pathologies with chronic proinflammatory status, offering potential relevance in SLE. This systematic review aimed to evaluate the utility of skin autofluorescence (SAF)-a non-invasive proxy for AGE accumulation-as a biomarker for disease severity, activity, and impact in SLE patients. Following PRISMA guidelines, six studies assessing SAF and/or circulating AGEs and soluble RAGE (sRAGE) in SLE were analyzed. Findings consistently showed higher AGE levels in SLE patients compared to healthy controls, with several correlations between SAF/AGEs and disease features such as SLEDAI scores, organ involvement, inflammatory markers, and damage indices. Decreased sRAGE levels were also observed, possibly due to consumption by AGEs. Some studies further reported predictive associations between specific AGEs or their ratios with sRAGE and particular clinical phenotypes. Although heterogeneity among studies limits definitive conclusions, the AGEs-sRAGE axis-and especially SAF-emerges as a promising candidate for future biomarker development in SLE. Further large-scale longitudinal studies are needed to confirm its clinical utility.