Tetraspanin changes in septic blood are organized by cell type, with monocyte CD82 induction and leukocyte CD37 loss associated with mortality
Background: Tetraspanins organize membrane domains that regulate inflammation. The antagonistic pair CD82 (pro-inflammatory, pro-leakage) and CD151 (anti-inflammatory, anti-leakage) coordinate endothelial activation and dysfunction in severe inflammation such as sepsis. Whether blood-cell tetraspanin networks are reorganized cell-type-specifically in human sepsis and relate to mortality is unknown. Methods: We integrated bulk meta-analysis (8 ICU-sampled cohorts, 241 controls, 550 sepsis), 28-day survival analysis (GSE65682, n=468), single-cell RNA-sequencing (3 datasets, 1.6 million PBMCs from 184 donors), co-expression networks (WGCNA), immune deconvolution with composition-adjusted survival, and mortality prediction models judged against matched random-gene controls. Mendelian randomization tested whether inherited variation in tetraspanin expression alters sepsis susceptibility. Single-cell RNA-sequencing of LPS-challenged mouse lung provided an orthogonal test. Results: Thirteen of 33 tetraspanins changed significantly in septic blood (up: CD63, CD82, CD151, ROM1, TSPAN9, UPK1A; down: CD81, TSPAN3, TSPAN13, TSPAN32, TSPAN18, TSPAN4, TSPAN31), and the direction of change followed myeloid versus lymphoid lineage restriction, reflecting the leukocyte composition shift of sepsis. WGCNA placed CD82 and CD151 in distinct modules. The CD82:CD151 ratio did not predict 28-day mortality (HR=1.09, p=0.37). In the discovery cohort, CD37 was the strongest survival-associated tetraspanin (HR=0.72 per SD, FDR=0.002), even after adjusting for leukocyte composition (HR=0.70, p=0.007). Single-cell analysis of three datasets resolved two cell-type-specific programs, monocyte CD82 up-regulation and pan-leukocyte CD37 loss. CD37 expression was directionally protective in all three independent ICU cohorts, significantly so only in the largest. Mendelian randomization found no evidence that genetically proxied baseline tetraspanin expression affects sepsis susceptibility (0 of 24 genes). In mouse lung, we found macrophage CD82 increased and endothelial CD151 decreased after LPS. Conclusions: Blood-cell tetraspanin networks are reorganized cell-type-specifically in sepsis. Much of the bulk signal reflects leukocyte composition rather than a coordinated membrane program. The CD82/CD151 antagonism, established in endothelium, is not captured by whole-blood ratios, in which the two genes reflect different cell types.