Molecular Pathways Differentiate Hepatitis C Virus (HCV) Recurrence from Acute Cellular Rejection in HCV Liver Recipients

Abstract

Acute cellular rejection (ACR) and hepatitis C virus (HCV) recurrence (HCVrec) are common complications after liver transplantation (LT) in HCV patients, who share common clinical and histological features, making a differential diagnosis difficult. Fiftythree liver allograft samples from unique HCV LT recipients were studied using microarrays, including a training set (n = 32) and a validation set (n = 19). Two no-HCV-ACR samples from LT recipients were also included. Probe set intensity values were obtained using the robust multiarray average method (RMA) method. Analysis of variance identified statistically differentially expressed genes (P ≤ 0.005). The limma package was used to fit the mixed-effects models using a restricted maximum likelihood procedure. The last absolute shrinkage and selection operator (LASSO) model was fit with HCVrec versus ACR as the dependent variable predicted. N-fold cross-validation was performed to provide an unbiased estimate of generalization error. A total of 179 probe sets were differentially expressed among groups, with 71 exclusive genes between HCVrec and HCV-ACR. No differences were found within ACR group (HCV-ACR vs. no-HCV-ACR). Supervised clustering analysis displayed two clearly independent groups, and no-HCV-ACR clustered within HCV-ACR. HCVrec-related genes were associated with a cytotoxic T-cell profile, and HCV-ACR-related genes were associated with the inflammatory response. The best-fitting LASSO model classifier accuracy, including 15 genes, has an accuracy of 100% in the training set. N-fold cross-validation accuracy was 78.1%, and sensitivity, specificity and positive and negative predictive values were 50.0%, 90.9%, 71.4% and 80.0%, respectively. Arginase type II (ARG2), ethylmalonic encephalopathy 1 (ETHE1), transmembrane protein 176A (TMEM176A) and TMEM176B genes were significantly confirmed in the validation set. A molecular signature capable of distinguishing HCVrec and ACR in HCV LT recipients was identified and validated.

Proteome and computational analyses reveal new insights into the mechanisms of hepatitis C virus–mediated liver disease posttransplantation

“…We note that all patients received different combinations of immune-suppressing drugs, including treatment for graft rejection that trended with rapid fibrosis progression at 1 year post-transplant (Table 1). However, we did detect differential regulation of biological processes such as pro-inflammatory innate immune activities and positive regulation of interferon gamma (IFN-γ protein expression and down-stream targets consistent with those described during the transcriptional deregulation associated specifically with HCV recurrence, rather than acute cellular rejection (23). Not surprisingly, patients with progressive liver disease further exhibited an enrichment of differentially regulated proteins mapping to the IPA toxicologic functional category of liver fibrosis, including proteins associated with hepatic stellate cell activation (p < 0.05), and demonstrate the possibility of detecting protein abundance profiles consistent with hepatic damage weeks or months prior to clinical evidence of liver injury.…”

Abnormal accumulation of human transmembrane (TMEM)-176A and 176B proteins is associated with cancer pathology

“…However, when the author created a phage clone expressing TMEM176A and tested it in allogeneic sera (taken from different patients) with hepatitis B virus (HBV)-infected, with head and neck cancer, and healthy normal individuals, the TMEM176A protein was not reactive (Wang et al, 2002). Nevertheless, an increase in human TMEM176A mRNA transcript level has been observed in transplanted human livers that relapsed from hepatitis C virus (HCV) infection (Gehrau et al, 2011). Similarly, an elevated mouse Tmem176A transcript level has been detected in proximal tubule cells of the mouse kidney nephron (Nakajima et al, 2002).…”

“…Similar to TMEM176A, the level of human TMEM176B transcripts has been shown to be markedly elevated in transplanted livers that showed recurrence of HCV infection (Gehrau et al, 2011). On the other hand, the mRNA expression of rat Tmem176B (also known as rat TORID, or mouse Clast1/LR8) is highly correlated with tolerated allografts (transplanted tissue taken from a different individual of the same species) (Louvet et al, 2005; Condamine et al, 2010).…”

Biomarkers of disease differentiation: HCV recurrence versus acute cellular rejection

“…However, the implementation of WGE analyses permitted new insights about the molecular biology characterization of certain post-LT complications [13,23,28,37,38]. Furthermore, the extension of this technique to the follow-up of HCV recurrence patients might permit the diagnosis and surveillance of severity in the fibrosis progression, along with pathological evaluation [28].…”