Differential protein expression in endothelial cells exposed to serum from patients with acute graft‐vs‐host disease, depending on steroid response

Graft‐versus‐host disease (GVHD) is a complication of allogeneic haematopoietic cell transplantation. Endothelial injury is crucial as pathophysiological substrate for GVHD. GVHD first‐line treatment is high‐dose corticosteroids, although some patients are steroid‐refractory. Through the present study, we compared the endothelial proteomic profiles in response to serum from steroid‐refractory acute GVHD (SR‐aGVHD) and steroid‐sensitive acute GVHD (SS‐aGVHD) patients. Blood samples from SR‐aGVHD (n = 4) and SS‐aGVHD (n = 8) patients were collected at aGVHD diagnosis. Endothelial cell cultures were exposed (48 h) to patients' serum. Protein extraction and proteomic analysis were performed. Differences were statistically evaluated by multivariate analysis. Forty‐four proteins contributed to separate all samples into the two study groups, among which 15 participated significantly (p < 0.05), 10 exhibiting a fold change >1.2. Differentially expressed proteins were mainly associated with oxidative phosphorylation (Cytochrome C oxidase subunit 6B1, CX6B1), inflammation and angiogenesis (Apolipoprotein D, APOD), cell survival (Rapamycin‐insensitive companion of mTOR, RICTR), and oxidative stress (Riboflavin kinase, RIFK). This pilot study used a novel approach to distinguish the aGVHD response to steroid treatment. The proteins differentially expressed could constitute potential biomarkers for steroid‐treatment response. These findings signify a step forward to identify the mechanisms of response to steroids, of high clinical relevance considering the SR‐aGVHD elevated mortality.