BackgroundTimely resolution of innate immune responses activated by surgical intervention is crucial for patient recovery. While cytokines and innate immune cells are critical in inflammation resolution,the specific role of IL-18 in these processes remains controversial and underexplored.MethodsWe investigate determinants of successful recovery using peripheral blood samples from orthopedic surgery (ORT) patients (n?=?33) at T0 (before surgery),T1 (24 h after surgery) and T2 (3 days after surgery). Monocytes from ORT patients underwent immunophenotyping together with bulk transcriptomic analysis. We found that IL-18 strongly defines the recovery immune signature. These results were further validated in vitro by comparing IL-18 and TNF-? effects on monocytes,and in 3D human intestine organoids together with single cell (sc)-RNAseq analysis.ResultsTranscriptomics of ORT monocytes revealed upregulation of ITG family integrins,namely ITGB3 and ITGB5,CXCL family chemokines,notably CXCL1-3,CXCL5,and SCL/TAL1 factor controlling differentiation and migration,but not pro-inflammatory genes. Similar changes were observed in IL-18 stimulated healthy donor monocytes in vitro,including an increase in CD11b,CD64,and CD86 levels,accompanied by increased phosphorylation of Akt but not NF?B. These changes were attenuated in the presence of TNF-?,thus showing a unique role of IL-18 when acting alone without its most frequent paired cytokine TNF-?. We further confirmed that IL-18 induces monocyte-macrophage transition and migration using human intestinal organoids. Finally,TNF-?/IL-18 ratio showed a high predictive value of clinical severity in septic patients.ConclusionsWe propose a novel role of IL-18 on monocyte migration and macrophage transition characterizing successful orthopedic surgery recovery,as well as the ratio of IL-18/TNF-? as a novel marker of inflammation resolution,with potential implications for patient monitoring and therapeutic strategies.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12967-025-06652-7.
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