Immature Neutrophil Programs Associate with Burn Mortality and Extend Across Critical Illnesses

Severe burns provoke a systemic "genomic storm," yet cell states associated with divergent outcomes remain unclear. We profiled blood cells by single-cell RNA-Sequencing (73,014 cells) from adult burn patients within post-burn day 17 (n=4) and healthy donors (n=5), integrated data with bulk signatures of burn size, inhalation injury, and mortality, and evaluated clinical associations in the ABA National Burn Repository. Burn was associated with emergency hematopoiesis marked by expansion of hematopoietic stem/progenitor-like cells, immature neutrophils, and plasmablast/plasma cell states, alongside depletion of naïve CD4+/CD8+ T cells and dendritic cells. Larger burns (>20% TBSA) showed enrichment of humoral transcriptional programs, including plasmablast/plasma cell activation and suppression of cytotoxic CD8+ T-cell states. In multivariable models, inhalation injury was a stronger predictor of death (adjusted OR 1.9) than burn size (adjusted OR 1.1) and shared greater overlap with the most perturbed single cells in non-survivors; 55% of co-perturbed cells were neutrophils, implicating granulocyte dysregulation as a common lethal axis. We identified a neutrophil-specific 5-gene panel (OLFM4, RETN, LCN2, ARG1, BTNL3) that discriminated survivors vs non-survivors after burns (AUC >0.9) and generalized to trauma (n=158; AUC 0.81) and ICU COVID-19 (n=103; AUC 0.75), providing information orthogonal to conventional biomarkers and severity scores. Cytomorphology corroborated transcriptomic immaturity, with ~2-fold higher band neutrophils and larger neutrophil size in a fatal case. Computational drug-reversal analysis highlighted galectin-1 inhibition as a candidate modulator of mortality-associated neutrophil programs. Together, our findings suggest that immature neutrophils represent a shared immune feature across severe burns and other forms of critical illness. Structured Abstract Objective: To define cell-specific immune programs associated with burn size, severity, inhalation injury, and fatal trajectories.

Large burns provoke a "genomic storm" yet cellular drivers of divergent clinical outcomes remain unknown.

We profiled 73,014 immune cells (scRNA-seq) from 4 adult burn patients and 5 healthy donors, mapping TBSA, inhalation injury, and mortality signatures from bulk datasets onto single-cell atlas. Clinical patterns were validated using ABA NBR. 5-gene neutrophil panel was developed to predict burn mortality and tested in trauma (n=158) and ICU COVID-19 (n=103) cohorts.

Burns were associated with emergency hematopoiesis, expanding HSPCs, immature neutrophils, and plasmablasts while depleting naïve CD4+/CD8+ T cells. Large burns (>20% TBSA) showed enrichment of humoral responses by activating plasmablasts and plasma cells at the expense of CD8+ T-mediated immunity. While >20% TBSA increased mortality (OR 1.1), inhalation injury was a stronger independent predictor (OR 1.9) and shared 55% of its most perturbed cells with non-survivors, converging on neutrophils as the dominant transcriptional state. 5-gene immature neutrophil signature predicted burn mortality with AUC >0.9, generalized to trauma (AUC 0.81) and COVID-19 (AUC 0.75), and was orthogonal to conventional biomarkers and severity scores. Non-survivor had ~2-fold greater band neutrophils, supporting neutrophil nuclear segmentation and size as potential indicators of burn severity. In silico screening identified galectin-1 inhibition as a potential suppressor of death-associated neutrophil programs.

Immature neutrophil surges associate with mortality in burns, trauma, and COVID-19. 5-gene panel may identify this risk and therapeutic modulation of these cells will reveal whether they are modifiable features of critical illness.