Department of Pathology, University of Chicago, The University of Chicago Medicine, Chicago, IL.
Department of Bioengineering, University of Illinois at Chicago, Chicago, IL.
Transplantation. 2019 Apr;103(4):698-704. doi: 10.1097/TP.0000000000002465.
Antibody-mediated rejection (AMR) in cardiac allograft recipients remains less well-understood than acute cellular rejection, is associated with worse outcomes, and portends a greater risk of developing chronic allograft vasculopathy. Diffuse immunohistochemical C4d staining of capillary endothelia in formalin-fixed, paraffin-embedded right ventricular endomyocardial biopsies is diagnostic of immunopathologic AMR but serves more as a late-stage marker. Infrared (IR) spectroscopy may be a useful tool in earlier detection of rejection. We performed mid-IR spectroscopy to identify a unique biochemical signature for AMR.
A total of 30 posttransplant formalin-fixed paraffin-embedded right ventricular tissue biopsies (14 positive for C4d and 16 negative for C4d) and 14 native heart biopsies were sectioned for IR analysis. Infrared images of entire sections were acquired and regions of interest from cardiomyocytes were identified. Extracted spectra were averaged across many pixels within each region of interest. Principal component analysis coupled with linear discriminant analysis and predictive classifiers were applied to the data.
Comparison of averaged mid-IR spectra revealed unique features among C4d-positive, C4d-negative, and native heart biopsies. Principal component analysis coupled with linear discriminant analysis and classification models demonstrated that spectral features from the mid-IR fingerprint region of these 3 groups permitted accurate automated classification into each group.
In cardiac allograft biopsies with immunopathologic AMR, IR spectroscopy reveals a biochemical signature unique to AMR compared with that of nonrejecting cardiac allografts and native hearts. Future study will focus on the predictive capabilities of this IR signature.
与急性细胞排斥反应相比，心脏移植受者的抗体介导的排斥反应（AMR）了解得较少，与较差的结果相关，并预示着发生慢性同种异体移植物血管病的风险更大。福尔马林固定、石蜡包埋的右心室心肌活检中毛细血管内皮的弥漫性免疫组织化学 C4d 染色可诊断免疫病理学 AMR，但更多地作为晚期标志物。中红外（IR）光谱可能是早期检测排斥反应的有用工具。我们进行了中红外光谱分析，以确定 AMR 的独特生化特征。
共对 30 例移植后福尔马林固定石蜡包埋的右心室组织活检（14 例 C4d 阳性，16 例 C4d 阴性）和 14 例正常心脏活检进行了 IR 分析。对整个切片进行了中红外图像采集，并确定了心肌的感兴趣区域。从每个感兴趣区域内的许多像素中提取光谱。将主成分分析与线性判别分析和预测分类器相结合应用于数据。
比较平均中红外光谱揭示了 C4d 阳性、C4d 阴性和正常心脏活检之间的独特特征。主成分分析与线性判别分析和分类模型相结合，表明从中红外指纹区域提取的这些 3 组的光谱特征允许对每个组进行准确的自动分类。
在具有免疫病理学 AMR 的心脏移植活检中，与非排斥性心脏移植物和正常心脏相比，IR 光谱揭示了 AMR 的独特生化特征。未来的研究将集中于该 IR 特征的预测能力。
