Association of donor hepatitis C virus infection status and risk of BK polyomavirus viremia after kidney transplantation

Kidney transplantation (KT) from deceased donors with hepatitis C virus (HCV) into HCV-negative recipients has become more common. However, the risk of complications such as BK polyomavirus (BKPyV) remains unknown. We assembled a retrospective cohort at four centers. We matched recipients of HCV-viremic kidneys to highly similar recipients of HCV-aviremic kidneys on established risk factors for BKPyV. To limit bias, matches were within the same center. The primary outcome was BKPyV viremia ≥1000 copies/ml or biopsy-proven BKPyV nephropathy; a secondary outcome was BKPyV viremia ≥10 000 copies/ml or nephropathy. Outcomes were analyzed using weighted and stratified Cox regression. The median days to peak BKPyV viremia level was 119 (IQR 87-182). HCV-viremic KT was not associated with increased risk of the primary BKPyV outcome (HR 1.26, p = .22), but was significantly associated with the secondary outcome of BKPyV ≥10 000 copies/ml (HR 1.69, p = .03). One-year eGFR was similar between the matched groups. Only one HCV-viremic kidney recipient had primary graft loss. In summary, HCV-viremic KT was not significantly associated with the primary outcome of BKPyV viremia, but the data suggested that donor HCV might elevate the risk of more severe BKPyV viremia ≥10 000 copies/ml. Nonetheless, one-year graft function for HCV-viremic recipients was reassuring.

Cytogenomic characteristics of murine breast cancer cell line JC

Background

Breast cancer (BC), one of the most frequent human tumors, is genetically and histologically heterogeneous. Treatment options can be adapted according to BC subtype. Still, research is necessary to characterize BC biology better and to study potential new treatment options. Murine BC-cell lines can be used as model systems in this respect.

Results

Here for the first time murine BC-cell line JC was cytogenomically characterized as being complex rearranged and near-tetraploid. Multicolor banding and array comparative genomic hybridization were applied and the result was in silico translated to the human genome.

Conclusions

Even though being commercially available, cell line JC was yet not much included in BC-research, most likely due to a lack of cytogenomic data. Thus, here comprehensive data is provided on chromosomal aberrations, genomic imbalances and involved breakpoints of JC cell line. Also JC could be characterized as a model for BC of luminal B type, basal-like tumor rather than for luminal A type.

Supplementary information

The online version of this article (10.1186/s13039-020-00524-z) contains supplementary material, which is available to authorized users.

High-grade urothelial carcinoma in a kidney transplant recipient after JC virus nephropathy: The first evidence of JC virus as a potential oncovirus in bladder cancer

Kidney transplant (KT) recipients have an increased risk for urothelial carcinoma. A role for JC virus (JCV) in human cancers is not yet proved but there is an increasingly reported association between BK virus (BKV) nephropathy and renourinary neoplasms. We report a KT recipient who developed a high-grade urothelial carcinoma 5 years after a diagnosis of JCV nephropathy and 9 years after kidney transplantation. Neoplastic tissue was positive for JCV DNA by real-time polymerase chain reaction (PCR). Immunochemical staining showed strong positivity for cell cycle markers (p16, p53, and Ki67) and for early viral protein JCV large T antigen (JCV LTag; using a broad polyomavirus antibody); however, late viral protein (VP1) stained negative. In contrast, in non-neoplastic urothelium, JCV DNA and all immunochemical markers were negative. These facts suggest that malignancy was induced by JCV. To the best of our knowledge, this is the first report of urothelial high-grade carcinoma associated with JCV nephropathy in a KT recipient.

Sirolimus and other mTOR inhibitors directly activate latent pathogenic human polyomavirus replication

Background

Human polyomaviruses can reactivate in transplant patients, causing nephropathy, progressive multifocal leukoencephalopathy, Merkel cell carcinoma, pruritic, rash or trichodysplasia spinulosa. Sirolimus and related mechanistic target of rapamycin (mTOR) inhibitors are transplant immunosuppressants. It is unknown if they directly reactivate polyomavirus replication from latency beyond their general effects on immunosuppression.

Methods

In vitro expression and turnover of large T (LT) proteins from BK virus, JC virus (JCV), Merkel cell polyomavirus (MCV), human polyomavirus 7 (HPyV7), and trichodysplasia spinulosa polyomavirus (TSV) after drug treatment were determined by immunoblotting, proximity ligation, replicon DNA replication, and whole virus immunofluorescence assays.

Results

mTOR inhibition increased LT protein expression for all 5 pathogenic polyomaviruses tested. This correlated with LT stabilization, decrease in the S-phase kinase-associated protein 2 (Skp2) E3 ligase targeting these LT proteins for degradation, and increase in virus replication for JCV, MCV, TSV, and HPyV7. Treatment with sirolimus, but not the calcineurin inhibitor tacrolimus, at levels routinely achieved in patients, resulted in a dose-dependent increase in viral DNA replication for BKV, MCV, and HPyV7.

Conclusions

mTOR inhibitors, at therapeutic levels, directly activate polyomavirus replication through a Skp2-dependent mechanism, revealing a proteostatic latency mechanism common to polyomaviruses. Modifying existing drug regimens for transplant patients with polyomavirus-associated diseases may reduce symptomatic polyomavirus replication while maintaining allograft-sparing immunosuppression.

Infectious Entry and Neutralization of Pathogenic JC Polyomaviruses

Progressive multifocal leukoencephalopathy (PML) is a lethal brain disease caused by uncontrolled replication of JC polyomavirus (JCV). JCV strains recovered from the brains of PML patients carry mutations that prevent the engagement of sialylated glycans, which are thought to serve as receptors for the infectious entry of wild-type JCV. In this report, we show that non-sialylated glycosaminoglycans (GAGs) can serve as alternative attachment receptors for the infectious entry of both wild-type and PML mutant JCV strains. After GAG-mediated attachment, PML mutant strains engage non-sialylated non-GAG co-receptor glycans, such as asialo-GM1. JCV-neutralizing monoclonal antibodies isolated from patients who recovered from PML appear to block infection by preventing the docking of post-attachment co-receptor glycans in an apical pocket of the JCV major capsid protein. Identification of the GAG-dependent/sialylated glycan-independent alternative entry pathway should facilitate the development of infection inhibitors, including recombinant neutralizing antibodies.

Amino Acid Sequences Mediating Vascular Cell Adhesion Molecule 1 Binding to Integrin Alpha 4: Homologous DSP Sequence Found for JC Polyoma VP1 Coat Protein

The JC polyoma viral coat protein VP1 was analyzed for amino acid sequences homologies to the IDSP sequence which mediates binding of VLA-4 (integrin alpha 4) to vascular cell adhesion molecule 1. Although the full sequence was not found, a DSP sequence was located near the critical arginine residue linked to infectivity of the virus and binding to sialic acid containing molecules such as integrins (3). For the JC polyoma virus, a DSP sequence was found at residues 70, 71 and 72 with homology also noted for the mouse polyoma virus and SV40 virus. Three dimensional modeling of the VP1 molecule suggests that the DSP loop has an accessible site for interaction from the external side of the assembled viral capsid pentamer.