Lipid signatures in two functionally selected effluents from clinically relevant postoperative pancreatic fistulasare associated with graded, cell type–specific transcriptional responses

Clinically relevant postoperative pancreatic fistula (CR-POPF) remains a major cause of morbidity after pancreatoduodenectomy, yet the biochemical composition of postoperative effluents and their effects on anastomotic healing remain poorly understood. We investigated whether CR-POPF effluents exhibit lipolysis-associated lipid signatures and induce defined responses in cellular model systems relevant to anastomotic healing. Drain effluents from 14 patients (7 CR-POPF, 7 non-POPF) underwent GC-MS lipid profiling. Metabolic viability assays (ATP-based readout of cellular stress responses) were performed in peritoneal mesothelial cells and human foreskin fibroblasts as stromal model systems relevant to anastomotic healing, as well as PanC-1 cells. Two CR-POPF effluents associated with reproducible reductions in metabolic viability were functionally selected for transcriptomic profiling. RNA sequencing was performed in mesothelial cells and fibroblasts after exposure to these effluents and monopalmitin. CR-POPF effluents showed coordinated enrichment of long-chain fatty acids and monoacylglycerides. Only a subset reproducibly impaired cellular metabolic viability. Transcriptomic profiling of the two functionally selected CR-POPF effluents revealed a lipid-responsive transcriptional signal across these biologically distinct effluent samples, characterized by induction of ANGPTL4, HMOX1, PLIN2, and PDK4 and consistent with a metabolic and stress-adaptive transcriptional response to lipid exposure. Activation followed a clear gradient (monopalmitin > AES1448 > GR1479) and was more pronounced in mesothelial cells than in fibroblasts. Functionally active CR-POPF effluent samples may carry lipid signals that are associated with a consistent transcriptional signal in peritoneal mesothelial cells and fibroblasts in functionally active effluent samples. The lipid-dependent amplitude and compartment-specific embedding of this signal support a hypothesis-generating framework derived from the two functionally selected CR-POPF effluents.