11 research outputs found
PolyQ-expanded ataxin-3 protein levels in peripheral blood mononuclear cells correlate with clinical parameters in SCA3: a pilot study
In view of upcoming clinical trials, quantitative molecular markers accessible in peripheral blood are of critical importance as prognostic or pharmacodynamic markers in genetic neurodegenerative diseases such as Spinocerebellar Ataxia Type 3 (SCA3), in particular for signaling target engagement. In this pilot study, we focused on the quantification of ataxin-3, the protein altered in SCA3, in human peripheral blood mononuclear cells (PBMCs) acquired from preataxic and ataxic SCA3 mutation carriers as well as healthy controls, as a molecular marker directly related to SCA3 pathophysiology. We established two different highly sensitive TR-FRET-based immunoassays to measure the protein levels of either total full-length, non-expanded and expanded, ataxin-3 or specifically polyQ-expanded ataxin-3. In PBMCs, a clear discrimination between SCA3 mutation carrier and controls were seen measuring polyQ-expanded ataxin-3 protein level. Additionally, polyQ-expanded ataxin-3 protein levels correlated with disease progression and clinical severity as assessed by the Scale for the Assessment and Rating of Ataxia. Total full-length ataxin-3 protein levels were directly influenced by the expression levels of the polyQ-expanded ataxin-3 protein, but were not correlated with clinical parameters. Assessment of ataxin-3 levels in fibroblasts or induced pluripotent stem cells allowed to distinguish mutation carriers from controls, thus providing proof-of-principle validation of our PBMC findings across cell lines. Total full-length or polyQ-expanded ataxin-3 protein was not detectable by TR-FRET assays in other biofluids like plasma or cerebrospinal fluid, indicating the need for ultra-sensitive assays for these biofluids. Standardization studies revealed that tube systems, blood sampling, and PBMC preparation may influence ataxin-3 protein levels indicating a high demand for standardized protocols in biomarker studies. In conclusion, the polyQ-expanded ataxin-3 protein is a promising candidate as a molecular target engagement marker in SCA3 in future clinical trials, determinable even in-easily accessible-peripheral blood biomaterials. These results, however, require validation in a larger cohort and further standardization of modifying conditions
Comparison of SL and TE in predicting clinical outcome.
<p>Comparison of SL and TE in predicting clinical outcome.</p
TE result and spleen length according to stage of fibrosis.
<p>TE result and spleen length according to stage of fibrosis.</p
Survival rates according to SL and TE measurement.
<p>Survival rates according to SL measurement with 120 mm cut-off and according to TE measurement with different cut-off values (B-D) for the combined cohort of PSC patients (Hamburg + Paris, see text). (log-rank test, p<0.001 each).</p
The Performance of TE Diagnosing Liver Fibrosis in PSC.
<p>Box plot of TE measurement depending on histological fibrosis stage F0-F4 (n = 62). The bottom and top of the boxes represent the 25<sup>th</sup> and 75<sup>th</sup> percentile and the horizontal lines the median. The whiskers are the minimum and maximum of the data.</p
Survival Rates of PSC Patients for Different TE Cut-off Values.
<p>Survival rates according to the different cut-off values (A-C) of TE measurement as previously suggested [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164224#pone.0164224.ref015" target="_blank">15</a>]. (log-rank test, p<0.0001).</p
Cutoff Values and Performance of TE Measurement for the Diagnosis of Fibrosis Stage.
<p>Cutoff Values and Performance of TE Measurement for the Diagnosis of Fibrosis Stage.</p