To investigate the effects of sivelestat sodium on the prognosis and Th17/Treg immune balance in patients with trauma-associated acute respiratory distress syndrome (ARDS), and to evaluate its clinical efficacy and potential mechanisms.

A prospective randomized controlled trial was conducted, enrolling 68 patients with mild-to-moderate trauma-associated ARDS admitted to the Intensive Care Unit (ICU) of Jiangdu People's Hospital of Yangzhou City from March 2022 to December 2024. Participants were randomly divided into a sivelestat sodium group (n=34) and a normal saline group (n=34). Both groups received standard treatment, while the experimental group additionally received sivelestat sodium (4.8 mg/kg/day via intravenous infusion pump for 5 days, extendable up to 14 days). The primary endpoint was 28-day mortality, and secondary endpoints included ICU mortality rate, ICU stay, ventilator-free days, etc. Enzyme-linked immunosorbent assay (ELISA) was used to monitor the levels of IL-6 and IL-10 in the peripheral blood of patients. Flow cytometry was used to detect the expression of Th17 (CD4+IL-17A+) and Treg cells (CD4+CD25+Foxp3+) in peripheral blood of patients. Statistical analyses were performed using STATA 17.0.

The 28-day mortality rate was 5.9% (2/34) in the sivelestat sodium group and 11.8% (4/34) in the control group, with no statistically significant difference between them (P＞0.05). Compared with the saline group, tno statistically significant difference was found in ICU mortality rate and ICU stay in the sivelestat sodium group. However, the 28-day ventilator-free days was longer in the sivelestat sodium group [28 (27.8, 28) vs. 28 (19.9, 28) days, P＜0.05]. Immunological analysis revealed that IL-6 levels [61.7 (45.8~101.7) pg/ml] and Th17 proportions [7.8% (4.8%~12.3%)] in the sivelestat sodium group were significantly lower than those of the control group [97.3 (56.7~133.3) pg/ml and 12.9% (9.1%~18.0%), respectively]. The Th17/Treg cell ratio was also significantly reduced [1.2 (0.6~1.5) vs 1.5 (0.9~2.8), P＜0.05], indicating suppression of inflammation via Th17/Treg balance modulation.

Sivelestat sodium improves oxygenation and prolongs ventilator-free days in trauma-associated ARDS patients, potentially by inhibiting Th17 cell differentiation and correcting immune imbalance. Although no significant mortality reduction was observed, this study provides novel evidence for immunotargeted therapy in trauma-associated ARDS, supporting early application in mild-to-moderate cases to optimize clinical outcomes.