Analysis of the effects of donor and recipient hepatitis C infection on kidney transplant outcomes in the United States

BACKGROUND

As Hepatitis C virus infection (HCV+) rates in kidney donors and transplant recipients rise, direct-acting antivirals (DAA) may affect outcomes.

AIM

To analyze the effects of HCV+ in donors, recipients, or both, on deceased-donor (DD) kidney transplantation (KT) outcomes, and the impact of DAAs on those effects.

METHODS

The Organ Procurement and Transplantation Network data of adult first solitary DD-KT recipients 1994-2019 were allocated into four groups by donor and recipient HCV+ status. We performed patient survival (PS) and death-censored graft survival (DCGS) pairwise comparisons after propensity score matching to assess the effects of HCV+ in donors and/or recipients, stratifying our study by DAA era to evaluate potential effect modification.

RESULTS

Pre-DAA, for HCV+ recipients, receiving an HCV+ kidney was associated with 1.28-fold higher mortality (HR _1.151.28_1.42) and 1.22-fold higher death-censored graft failure (HR _1.081.22_1.39) compared to receiving an HCV- kidney and the absolute risk difference was 3.3% (95%CI: 1.8%-4.7%) for PS and 3.1% (95%CI: 1.2%-5%) for DCGS at 3 years. The HCV dual-infection (donor plus recipient) group had worse PS (0.56-fold) and DCGS (0.71-fold) than the dual-uninfected. Donor HCV+ derived worse post-transplant outcomes than recipient HCV+ (PS 0.36-fold, DCGS 0.34-fold). In the DAA era, the risk associated with HCV+ in donors and/or recipients was no longer statistically significant, except for impaired PS in the dual-infected vs dual-uninfected (0.43-fold).

CONCLUSION

Prior to DAA introduction, donor HCV+ negatively influenced kidney transplant outcomes in all recipients, while recipient infection only relatively impaired outcomes for uninfected donors. These adverse effects disappeared with the introduction of DAA.

Abstract PR7: Visualizing the dynamic and heterogeneous responses of single cells to inhibitors of the growth factor signaling network

The growth factor signaling network, including the Akt, ERK, mTOR and other pathways, is deregulated in many diseases and is a prominent target for therapeutic inhibitors. The effectiveness of these inhibitors is limited by the existence of homeostatic feedback loops that act to restore signaling and attenuate the effects of inhibition. To obtain the single-cell data necessary to fully characterize these rapid and heterogeneous responses, we developed a library of mammary epithelial cells stably expressing over 90 fluorescent protein-based reporters. This library comprises reporters for: cellular processes including cell death, cell cycle, protein translation, and metabolism; kinases including ERK, Akt and AMPK; and microRNAs involved in the regulation of cellular differentiation and stress response. Using high-throughput live-cell microscopy and computational image analysis, we monitored the responses of these pathways to inhibitors of EGFR, ErbB2, PI3K, mTOR, MEK, Raf, and Bcl-2. This analysis revealed unexpectedly dynamic fluctuations in key pathways including ERK, Akt, and glycolysis. In one example, inhibition of EGFR transformed constitutive ERK activity into intermittent bursts of activity ranging in duration from 20-90 minutes with high cell-to-cell variability. Characterization of ERK activity pulses revealed that their frequency depended on the level of EGF receptor activity and that their duration was essential for controlling the commitment to cell proliferation. In sharp contrast, inhibition of MEK altered the amplitude, rather than the frequency, of ERK activity. Using these live-cell measurements in combination with high content immunofluorescence, we constructed a computational model of feedback loops controlling ERK activity pulses. Quantitative mapping of ERK output to proliferation rate revealed a distinct and exquisitely sensitive threshold of ERK output required for proliferation. Potential strategies for reducing ERK output below this threshold and effectively blocking proliferation include dual inhibition of upstream regulators or intermittent high-dose inhibition. Single-cell quantitative analysis of inhibitor responses is now being extended to other pathways to identify signaling dynamics and information transfer properties that enable effective therapeutic targeting of the network.

This proffered talk is also presented as Poster A19.

Citation Format: John Albeck, Yin P. Hung, Gregory Leya, Gary Yellen, Gordon Mills, Joan Brugge. Visualizing the dynamic and heterogeneous responses of single cells to inhibitors of the growth factor signaling network [abstract]. In: Proceedings of the AACR Special Conference on Chemical Systems Biology: Assembling and Interrogating Computational Models of the Cancer Cell by Chemical Perturbations; 2012 Jun 27-30; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2012;72(13 Suppl):Abstract nr PR7.

Abstract LB-418: A live-cell miRNA reporter library for identifying non-genetic drug resistance networks at single-cell resolution

The effectiveness of targeted cancer therapies is limited by cellular resistance. Emerging research has demonstrated that a major source of drug resistance is non-genetic: pre-existing heterogeneity in protein expression levels, or induction of adaptive feedback loops, can protect cells from the effects of kinase inhibitors and other drugs. Traditional genomic or proteomic techniques may fail to identify key resistance pathways because they do not stem from changes in genetic sequences, are often transient in nature, and may operate in only a subset of cells within a population. To address this challenge, we have developed a library of over 80 live-cell reporters that, in combination with high-throughput automated microscopy, enable the identification of transiently active resistance pathways in drug-treated cells. These reporters are based on miRNA regulatory sequences since numerous miRNAs have been implicated in drug resistance and because miRNAs can act as surrogate indicators for the activation of signaling pathways in which they participate. We have developed and validated a novel ratiometric reporter design for optimal detection of miRNA expression changes at single-cell resolution and have constructed retroviral reporters for miRNAs involved in apoptosis, cell proliferation, cancer stem cells, metabolism, and stress response. Live imaging of mammary epithelial cells treated with inhibitors targeting EGFR, PI3-K, mTOR, and Bcl-2 identified a set of 20-30 miRNA reporters with significant expression level alterations in surviving cells that are consistent with miRNA expression changes characteristic of cancer cells. Bioinformatic analyses of these miRNAs revealed commonly regulated pathways and downstream targets, including Bcl-2 and Cyclin-D. Thus, the reporter library is capable of identifying, in living cells, pathways involved in the cellular response to targeted cancer therapies. By identifying components of the signaling networks controlling inhibitor resistance, we hope to discover new drug targets that can be used to sensitize tumor cells to existing targeted therapies. The reporter library can be easily expressed in most cell lines of interest and should have broad utility for identifying transiently regulated pathways.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-418. doi:1538-7445.AM2012-LB-418