Abstract WP356: Acute stroke proteomics reveals plasma increases in brain proteins and suppression of inflammatory and growth factor pathways in minor to moderate strokes

Introduction: Patients with minor to moderate strokes, commonly defined by NIHSS scores ≤15, frequently suffer significant long-term disability from motor deficits, cognitive impairment, fatigue, pain, depression, and other behavioral changes. In this study, we analyzed plasma proteomics of acute ischemic stroke compared to healthy controls (HCs). Methods: Platelet-depleted plasma was collected from 106 participants ~2 days following acute stroke. Olink proteomics was used to measure 2944 proteins, with 2884 passing quality control. Each stroke participant was age- and sex-matched to 2 adjudicated HCs from concurrently processed plasma samples. The resulting differences in protein levels were ranked by log2 fold change for gene set enrichment analysis (GSEA). Results: Matching yielded 102 stroke participants and 204 HCs, with median age 69.5 years and 58.8% male in each group. Four outlier cases without suitable HCs were excluded. HCs had longer plasma storage time and higher education (Table 1) but did not have vascular comorbidities collected. Strokes were largely minor (admission NIHSS 4.0 [IQR 2.0, 9.5]), with MRI infarct volume 3.4 [IQR 0.5, 17.6] ml. Differential protein expression analysis (Fig.1) demonstrated upregulation of proteins associated with neural injury, including GFAP, NEFL, and CEND1 (Log2FC=0.98–2.86, p<0.001). All were loosely associated with increased stroke volume and admission NIHSS (R 2 =0.14–0.33, p<0.001). Interestingly, upregulation of IL-6 (Log2FC=2.05, p<0.001) was more highly associated with NIHSS (R 2 =0.12, p<0.001) than stroke volume (R 2 =0.014, p=0.24). There was no prominent upregulation of other immune proteins; in fact, GSEA (Fig.2) found significant down regulation of immune pathways associated with Fc gamma, B and T cell, and chemokine receptor signaling. Growth factor pathways (e.g., VEGF, EGF, and insulin) were also downregulated (adjusted p<0.01). Covariate analysis showed that sample storage time and also vascular risk factors such as HbA1c, LDL, and BMI were not primary drivers of the most differentially expressed proteins. Conclusions: This study of acute stroke plasma proteomics demonstrates that intracellular and membrane CNS proteins such as GFAP, NEFL, and CEND1 are increased in plasma even in minor-moderate ischemic strokes. Immunodepression and growth factor suppression were also observed. Both may relate to longer-term outcomes seen in similar stroke populations.