Polyomavirus Diversität und inflammatorische Chemokine

This study aims to find new clinical markers for Polyomavirus Associated Nephropathy (PVAN), a severe vial disease which may occur in kidney transplant recipients. PVAN is mainly caused by BK Virus (named after the initials of the patient in whom the virus was initially detected), which is one of 13 currently known Human Polyomaviruses (HPyVs). Most of the HPyVs show a high prevalence in the common population and typically do not cause any symptoms in immunocompetent individuals. However, when kidney transplant recipients receive immunosuppressive therapy to prevent allograft rejection, BK-Virus may cause PVAN. The underlying mechanisms for PVAN development remain unclear. The question arises whether chemokines could play a role in the pathogenesis of PVAN. Chemokines are small cytokines which attract and activate certain types of immune cells to the infected tissue and thereby regulate all inflammatory processes. Furthermore, it remains to be elucidated whether other HPyVs, rather than BK Virus, could also cause PVAN development, be it that these viruses cause direct damage in the renal tissue or induce chemokines and thereby trigger inflammation. Hypothesis: The diverse spectrum of HPyVs and the chemokines they induce affect the pathogenesis of PVAN and can therefore be used as clinical markers to identify kidney transplant recipients who will develop PVAN. Methods: In this study serum samples from 600 kidney transplant recipients (with and without PVAN) will be simultaneously investigated for 13 HPyVs as well as for 10 chemokines. In a genome analysis the whole spectre of all known HPyVs will be quantitatively assessed for virus- specific nucleic acid using a method based on the Luminex XMAP (multi-analyte- profiling) technology, which was recently established and is only available in Prof. Hedmans lab in Helsinki. In addition, a panel of 10 chemokines (CCL-2, CCL-5, CCL-7, CCL-8, CCL- 18, CCL-20, CXCL-9, CXCL-10 and CXCL-16) will be quantitated using ELISA and Luminex technology, which uses different fluorescent color-coded microspheres (beads), allowing a simultaneous quantitative analysis of multiple targets. Originality: This is the first study that aims to comprehensively investigate such a large cohort of kidney transplant recipients for a large panel of chemokines as well as to simultaneously assess the whole spectrum of all known HyPVs, using a recently developed assay which is only available at the University of Helsinki. Results from this study could significantly contribute to understanding of PVAN development. Furthermore, certain HPyVs in association with distinct chemokine patterns could serve as clinical indicators to identify kidney transplant recipients who are at risk to develop PVAN.

The performed study aimed to investigate whether the range of 13 Human Polyomavirus (HPVs), together with certain small, pro-inflammatory cytokines (chemokines), might contribute to the development of Polyomavirus-associated nephropathy (PVAN), a severe viral disease which affects kidney transplant recipients, and could therefore be used as diagnostic markers. While the two HPyVs BK- and JC-Virus (named after the initials of the patients in which the viruses were first detected) had been previously identified as cause for PVAN, it was to date unclear whether the other 11 HPyVs might also facilitate the development of PVAN, either by directly causing tissue damage or by inducing an inflammatory chemokine responses. Indeed, results from the present virus analysis demonstrate that PVAN - in accordance with previous studies is indeed caused by BK-Virus (and in few cases also by JC-Virus), but not by the 11 additionally investigated HPyVs. These results were acquired by analyzing 400 serum and 386 urine samples from 98 kidney transplant recipients using a newly established Multiplex-method, which allows the simultaneous analysis of 13 HPyV in one single test. In particular, using this Multiplex analysis 4 of 11 the HPyVs, which were investigated in addition to BK- and JC-Virus, were detected in serum and/or urine samples (Human Polyomavirus 6, Merkel-Cell Polyomavirus, Human Polyomavirus 9 and Trichodysplasia spinulosa associated Polyomavirus). In total these viruses were detected in 11 serum- und 21 urine samples from 21 transplant recipients. By correlating episodes of HPyV detection to parameters and test results acquired during the post-transplant follow-up due to the clinical routine diagnostics (defining episodes of verified PVAN), it was demonstrated that detection rates were neither increased in patients who developed PVAN (in comparison to the kidney transplant recipients in whom no PVNA occurred), nor at the time point of PVAN diagnosis (during the individual post-transplant follow-up). The additionally performed chemokine analysis, however, revealed that the progression of BK-Virus replication towards the development of manifest PVAN was associated with a stepwise and significant increase of serum and urine concentration of the chemokine CXCL-10. This observation was made by the quantitative analysis of the CXCL-10 concentration in 186 pairs of serum and urine samples, acquired at the same day respectively, from 95 kidney transplant recipients. CXCL-10 serum concentrations were furthermore compared to concentrations of 3 other chemokines (CCL-8, CCL-20 and CXCL-16), which were also simultaneously assessed by Multiplex-Analysis. As a result, it was demonstrated that CXCL-10 in comparison with the other investigated chemokines showed the statistically strongest association with PVAN occurrence and displayed the highest predictive power for this viral disease, indicating that it might serve as clinical marker for PVAN development.