Integrative Proteomic and Transcriptomic Profiling Identifies Candidate Biomarkers for Discriminating Anaphylactic from Cardiac Sudden Death.

LC-MS/MS-based serum proteomic analysis identified fibronectin 1 (FN1), platelet glycoprotein Ibα chain (GP1BA), and platelet factor 4 (PF4) as candidate biomarkers distinguishing atherosclerosis from anaphylaxis mouse models.

• Mouse models used were Ldlr-/- atherosclerosis (AS) mice and ovalbumin-induced anaphylaxis (AP) mice.
• Proteomic discovery was performed using LC-MS/MS-based serum proteomics.
• Candidates were validated by parallel reaction monitoring (PRM), enzyme-linked immunosorbent assay (ELISA), and immunohistochemistry (IHC).
• Validation was conducted in both a combined AS + AP mouse model and in post-mortem human cardiac and bronchiolar epithelial tissue.

In mouse serum, FN1, GP1BA, and PF4 levels were significantly elevated in the atherosclerosis (AS) group, whereas only FN1 was markedly downregulated in anaphylaxis (AP) mice.

• Serum FN1 showed differential regulation between AS (elevated) and AP (downregulated) groups.
• GP1BA and PF4 were elevated in AS mice but did not show significant downregulation in AP mice.
• This pattern identifies FN1 as the key differential serum biomarker between the two conditions in the mouse model.
• Results were validated by both PRM and ELISA following initial LC-MS/MS discovery.

In post-mortem human myocardial samples, FN1, GP1BA, and PF4 were all upregulated in sudden death from coronary heart disease (SD-CHD), with FN1 showing the greatest increase.

• All three candidate biomarkers — FN1, GP1BA, and PF4 — were upregulated in SD-CHD myocardial tissue.
• FN1 showed the greatest magnitude of increase among the three markers in cardiac tissue.
• IHC was used to assess protein expression in post-mortem human cardiac tissue.
• PF4 and GP1BA were noted to aid in SD-CHD diagnosis alongside FN1.

In human airway epithelium from post-mortem samples, FN1 was upregulated in anaphylactic sudden death (ASD) and ASD with coronary atherosclerosis (ASD + CAS) groups, while GP1BA was downregulated.

• FN1 upregulation in bronchiolar epithelial tissue was observed in both the ASD group and the ASD + CAS group.
• GP1BA showed downregulation in airway epithelium, contrasting with its upregulation in myocardial tissue of SD-CHD cases.
• IHC was used to assess protein expression in post-mortem human bronchiolar epithelial tissue.
• The tissue-specific differential expression of GP1BA supports its utility in distinguishing ASD from SD-CHD.

A multimarker, multilevel diagnostic framework combining FN1, GP1BA, and PF4 across serum and tissue compartments provides a molecular strategy for forensic identification of complex sudden death cases.

• FN1 was identified as the key differential biomarker across both mouse serum and human post-mortem tissue contexts.
• PF4 and GP1BA were identified as aiding specifically in SD-CHD diagnosis.
• The framework integrates findings from serum proteomics, cardiac tissue, and airway epithelial tissue.
• The approach is designed to address the forensic diagnostic challenge of distinguishing ASD from SD-CHD, including in cases with overlapping pathology (ASD + CAS).