Markers of Endotoxemia and Inflammation are Associated with Digital Ulcers in Systemic Sclerosis Patients

Background: The aim of this study was to evaluate the possible role of lipopolysaccharide-binding protein (LBP) and interleukin 6 (IL-6) in the development of digital ulcers (DUs) in Systemic sclerosis (SSc). Methods: 60 SSc patients were enrolled and tested for serum levels of LBP and IL-6. The development of DUs was assessed in a 12-month follow-up period. Results: Median LBP and IL-6 were 107.445 ng/mL and 10.8 pg/mL whilst 33.3% patients had LBP >= 11995 ng/mL and 51.7% patients had IL-6 >= 12.5 pg/mL. DUs history were present in 41.7% SSc patients and at follow-up 23.3% patients developed new DUs. Baseline LBP (14105 ng/mL vs 10355 ng/mL, p < .001) and IL-6 (195 pg/mL vs 9.4 ng/mL, p < .001) were higher in SSc patients with new DUs. The ROC curves showed a good diagnostic accuracy for a cut-off of LBP >= 11995 ng/mL [AUC = 0.804 (95% CI = 0.656-0.951), p < .001] and for a cut-off of IL-6 >= 12.5 pg/mL [AUC = 0.897 (95% CI = 0.783-1.000), p < .001]. Free survival from new DUs was shorter in SSc patients with increased LBP (p < .001) or IL-6 (p = .003). Conclusions: LPB or IL-6 could play a role in digital microvascular damage of SSc patients.