131 Alteration of circulating free fatty acids in patients with pemphigus vulgaris

Free fatty acids (FFA) exert many immune-modulatory functions and have been associated with autoimmune diseases. Short chain FA (SCFA), mainly derived from the gut microbiota, include anti-inflammatory molecules such as propionic (PA), acetic, butyric (BA) and valeric (VA) acids, while medium (MCFA) and long chain FA (LCFA), mainly derived from the diet, include pro-inflammatory molecules, such as caproic acid (CA) and palmitic acid. Circulating FFA were retrospectively analyzed through a gas chromatography–mass spectrometry method in the serum of 17 PV patients at the baseline and 6 months after immunosuppressive treatments, and 17 healthy controls (HC). Circulating FFA were correlated with the Pemphigus Disease Activity Index (PDAI) and serum concentrations of Tumor Necrosis Factor (TNF)-α, Interleukin (IL)-17A, IL-5, IL-10 and IL-21, evaluated by Luminex MAGPIX detection system. Principal Component analysis computed on FFA abundances with Bray Curtis index revealed significant differences in the profile of SCFA (p=0,012), MCFA (p=0,00015) and LCFA (p=0,035) between PV patients and HC, which were not significantly changed by immunosuppressive treatments. At the single FFA level, PV patients showed a significant lower serum concentration of PA (p<0.0005), BA (p<0.0005) and VA (p=0.05) relative to HC, while CA (p<0.0005) and palmitic acid (p=0.0006) were over-represented. After treatment, PV sera showed a significant decrease of CA (p=0.035) and a further increase of palmitic acid (p=0.046). No significant correlations emerged between circulating FFA and either PDAI or the level of the tested cytokines. In sum, PV is associated with significant alterations of the serum profile of FFA. Deeper insights into the immunomodulatory role of these molecules may pave the way for personalized dietary interventions in PV.