BACKGROUND Whey acidic protein/four-disulfide core domain 21 (Wfdc21), also known as Lnc-DC, it has been reported to be correlated with immune response. However, the role of Wfdc21 in the pathogenesis of sepsis is still unknown. In the present study, we aimed to investigate the role of Wfdc21 in the pathogenesis of sepsis. MATERIAL AND METHODS The cecal ligation and puncture (CLP)-induced sepsis model was established in Balb/c mice. Animals were euthanized 4, 8, 16, or 24 h after CLP. The glycogen distribution in the kidney and liver was checked by Periodic acid-Schiff (PAS) staining. Changes in the serum interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations were monitored with ELISA, and Wdfc21 expression was determined by qPCR. Mouse macrophage-like RAW264.7 cells were treated with different doses of lipopolysaccharide (LPS) from Escherichia coli to mimic sepsis in vitro. Western blot analysis was performed to confirm whether LPS-induced in vitro sepsis was correlated with the involvement of the Stat3/TLR4 signaling pathway. In addition, RAW 264.7 cells were infected with lentiviruses containing Wfdc21 shRNA to further confirm the role of Wfdc21 in the pathogenesis of sepsis. RESULTS We found that Wfdc21 level was elevated in the CLP-induced animal model and LPS-treated RAW264.7 cells. Furthermore, the downregulation of Wfdc21 modulated the concentration of pro-inflammatory factors in LPS-treated macrophages, such as IL-1β and TNF-α, in LPS-treated macrophages. This regulatory effect was mediated through the Stat3/TLR4 signaling pathway, since Wfdc21 can regulate p-Stat3 and TLR4 levels in LPS-treated macrophages. CONCLUSIONS Wfdc21 plays a critical role in the pathogenesis of sepsis and may provide a therapeutic target for sepsis treatment.