RNA Sequencing Reveals a Conserved Mechanism of T Cell-Mediated Rejection in Vascularized Composite Allotransplantation Across Anatomical Sites
Year: 2023
Type: article
Abstract: PURPOSE: Despite substantial technical advances that make vascularized composite allotransplantation (VCA) viable for patients with devastating soft tissue injuries, acute rejection remains a major morbidity, with approximately 85% of patients experiencing a rejection episode within the first postoperative year(1). The molecular mechanisms of VCA rejection have not yet been fully elucidated, including its potential variation across anatomical sites. While there is some data to suggest disparate histopathological findings between oral mucosa and skin(2,3), differences between the face and hand remain unexplored. METHODS: NanoString RNA sequencing (RNAseq) was performed on 27 FFPE skin biopsies (16 face, 11 hand) from 3 VCA recipients; 7 were categorized as nonrejection (NR) and 20 as acute rejection (AR) by clinical status. Data analysis and visualization was performed using the NanoTube and ggplot2 packages in R, in addition to Metascape for pathway analysis. RESULTS: Upon principal components analysis (PCA), AR samples grouped separately from NR samples, without discernable clustering by patient or anatomical site. These findings were confirmed with hierarchical heatmap clustering of gene fold changes. We then compared fold changes from AR face biopsies to AR hand biopsies, which yielded a strong positive correlation across anatomical site (r≥0.38, p<0.05). Indeed, AR face and AR hand biopsies each exhibited 151 DEGs when compared to NR samples, with 127 of these DEGs overlapping between the face and hand. With such similarities in rejection between anatomical sites, we aggregated face and hand samples for downstream differential expression analysis. We found that differentially expressed genes in AR were highly enriched for adaptive immune response, leukocyte activation, and chemokine pathways (p<0.05). Finally, using a regularized regression model, we determined 7 genes that most significantly correlated with clinical rejection: CCL5, NKG7, CD8A, CD38, FASLG, SH2D1A, and KLF2. CONCLUSIONS: Our results demonstrate that the molecular mechanism of acute rejection in VCA appears to be conserved across different recipient anatomical sites. Antigen-activated T cells and NK cells mediate AR through production of cytokines and recruitment to graft tissue. In particular, cytotoxic and apoptotic markers such as CD8A, NKG7, and FASLG are highly diagnostic for clinical evidence of graft damage. Longitudinal sampling for RNAseq will identify key genes driving the mechanism of VCA rejection and inform targeted therapies. References: 1. Petruzzo P, Lanzetta M, Dubernard JM, et al. The International Registry on Hand and Composite Tissue Transplantation. Transplantation. 2010 Dec 27;90(12):1590–4 2. Bergfeld W, Klimczak A, Stratton JS, et al. A Four-Year Pathology Review of the Near Total Face Transplant. Am J Transplant. 2013;13(10):2750–64. 3 Kanitakis J, Badet L, Petruzzo P, et al. Clinicopathologic monitoring of the skin and oral mucosa of the first human face allograft: Report on the first eight months. Transplantation. 2006 Dec 27;82(12):1610–5
Language: English
Subfield: Transplantation
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,195
OpenAlex ID: W4387738516