Human-porcine transcriptomics reveals resuscitation-responsive pathways in trauma shock

Problem Statement
Haemorrhage remains the leading preventable cause of death in trauma, driven primarily by the ischaemic consequences of shock that current resuscitation strategies fail to adequately address. While trauma triggers a "genomic storm" of immune and metabolic dysregulation within minutes of injury, it remains unclear whether these transcriptomic trajectories are immutable or if they can be modulated by therapeutic interventions. Furthermore, the specific molecular pathways that should be augmented or inhibited to improve clinical outcomes have not been systematically identified. Preclinical models offer controlled environments for investigation but face challenges in translation due to species differences and the lack of experimental validation of treatment effects in human observational data.

Methodology
The authors employed an integrated cross-species experimental medicine framework combining human observational data with a controlled porcine model of traumatic haemorrhagic shock.

• Human Cohort: Transcriptomic data was analyzed from 458 trauma patients enrolled in the ACIT-II study, focusing on those with blunt trauma, admission blood samples, and complete datasets. Patients were stratified by injury severity (ISS), shock status (base deficit >6), and 28-day mortality.
• Porcine Model: Fifty pigs underwent a controlled trauma and haemorrhage protocol, followed by randomization into four treatment arms: no resuscitation (control), saline, saline with noradrenaline, or blood products. Serial blood samples were collected pre-injury, post-injury, and at multiple intervals up to 480 minutes.
• Analytical Approach:
  • Differential Expression & Enrichment: RNA-sequencing data was processed to identify genes associated with injury severity, shock, and mortality. Gene Set Enrichment Analysis (GSEA) was used to identify dysregulated pathways.
  • Network Preservation: Weighted Gene Co-expression Network Analysis (WGCNA) was used to assess the conservation of human gene co-expression modules in the porcine model.
  • Latent Factor Analysis: Independent Component Analysis (ICA) was applied to the human cohort to extract 40 distinct, transcriptionally independent "factors" representing coordinated biological programs. These factors were validated in the porcine model and an independent human cohort.
  • Treatment Responsiveness: Linear mixed models were used to identify "treatment-sensitive shock factors" (TSS factors)—signatures that were associated with human shock and exhibited dynamic temporal profiles dependent on the treatment type in pigs.
  • Drug Repurposing: The authors performed in silico screening using the LINCS L1000 database to identify small molecules and mechanisms of action (MoA) that could reverse the shock-associated transcriptional signatures, specifically focusing on the TSS factors.

Key Results

• Transcriptomic Overlap: There was a high degree of concordance between shock-associated and mortality-associated gene signatures in humans (93% overlap, Pearson's r = 0.90).
• Cross-Species Conservation: 87% (20/23) of human trauma-associated co-expression modules were significantly preserved in the porcine model, particularly those governing neutrophil degranulation and chemokine signaling. However, interferon signaling and antimicrobial peptide pathways showed less conservation.
• Treatment Modifiability: The porcine model demonstrated that shock-induced transcriptomic trajectories are not fixed. Blood product resuscitation effectively reversed shock-associated transcriptional changes (Pearson's r = -0.81 with human shock enrichment scores), normalizing maladaptive pathways. In contrast, noradrenaline treatment exacerbated stress responses and inflammatory signatures.
• Identification of TSS Factors: Eight factors were identified as both shock-associated in humans and responsive to treatment in pigs.
  • Factor H14: The dominant predictor of injury severity, shock, and mortality. It is enriched for p38-MAPK/AP-1 stress signaling, neutrophil activation, and chemokine pathways (e.g., CXCL8). H14 was sustained by noradrenaline but suppressed by blood products.
  • Factor H12: Enriched for neutrophil degranulation and antimicrobial peptides; suppressed by blood products but elevated by noradrenaline.
  • Factor H3: Associated with cytotoxic lymphocyte (NK/CD8) activity; elevated by noradrenaline.
  • Factor H25: A heat-shock response factor that was downregulated in shock but partially restored by blood transfusion.
  • Factors related to interferon responses (H18) and haemostasis (H11) were not significantly modifiable by the tested treatments.
• Therapeutic Candidates: In silico screening identified p38 MAPK inhibitors as the strongest candidates for reversing the H14 signature. Other potential candidates included PDE4 inhibitors and mTOR inhibitors. Conversely, tubulin polymerization inhibitors and NFκB inhibitors were found to align with shock signatures, potentially worsening outcomes.

Significance and Claims
The paper claims to provide the first large-scale human transcriptomic dataset specifically focused on trauma haemorrhagic shock that tests the treatment responsiveness of leukocyte transcript programs within an experimental medicine framework. The study establishes that:

1. Modifiable Pathways Exist: The "genomic storm" of trauma shock contains specific, modifiable components. The authors identify stress-responsive signaling (specifically p38-MAPK), neutrophil activation, and cytotoxic lymphocyte regulation as key nodes that can be altered by resuscitation strategy.
2. Validation of Resuscitation Strategies: The molecular data supports clinical observations that blood product resuscitation is superior to saline or noradrenaline in resolving maladaptive inflammatory states, while noradrenaline may perpetuate stress responses.
3. Therapeutic Prioritization: The study prioritizes p38-MAPK inhibition as a viable therapeutic strategy for trauma shock. The authors note that several selective p38 inhibitors (e.g., TAK-715, doramapimod, SB-203580) have established safety profiles and prior human experience, suggesting a feasible translational pathway for prospective evaluation in controlled trauma platforms.
4. Methodological Framework: The authors present a systematic approach combining human observational data with experimental randomization in animals to identify causal, treatment-responsive molecular targets, offering a resource for future drug repurposing in trauma care.

The paper concludes by acknowledging limitations, including the use of bulk whole-blood analysis (which may miss endothelial responses), the reliance on in silico drug screening, and the associative nature of the findings, emphasizing the need for specific mechanistic studies and human experimental medicine trials to validate these targets.