Periodic Reporting for period 1 - MetALS (Investigating the pharmacokinetic properties of toxic metals and heat shock proteins as risk factors in Amyotrophic Lateral Sclerosis)
Reporting period: 2019-10-01 to 2021-09-30
Amyotrophic Lateral Sclerosis (ALS) is a terminal neurodegenerative condition of largely unknown aetiology with an incidence in across Europe of 1 to 3 per 100,000 people and a lifetime risk of approximately 1:300. ALS is invariably fatal with a median survival of approximately 3 years, although a subset of patients have longer survival. ALS typically presents with a history of progressive weakness and the presence of mixed upper and clinically typified by onset muscle wasting, however it is increasingly recognized to also include cognitive and behavioural deficits in some cases. Research of ALS, as the most prevalent motor neurone disease (MND), is prioritized in the EU’s Joint Programme – Neurodegenerative Disease Research(JPND). The cause of ALS remains largely unknown, with the exception of the 10-15% of cases known to have genetic causes. Recent theory suggests that genetic pre-disposition combined with environmental exposures over time result in molecular changes in a stepwise process. Exposure to toxic metals has been frequently suggested as a risk factor for ALS in epidemiological studies and studies of occupational exposure. Toxic metals can affect a wide range of biological processes of relevance in neurodegeneration, and several toxic metals that are of interest in ALS, (cadmium, chromium, lead and mercury), are also listed as priority substances for monitoring and health related research studies by the Human Biomonitoring for Europe (HBM4EU) project. Additionally, toxic metals are known to be an exogenous trigger of the heat shock response, and serum heat shock proteins (HSP’s) have been reported to be elevated in ALS patients. Longitudinal trends of metals and HSP concentrations are likely an important unrecognized factor, and the dynamic nature of toxic metal exposure has been rarely considered in ALS studies. However, to date, data from longitudinal sampling of toxic metal biomarkers in ALS patients, and in healthy individuals, is lacking.
The aim of the MetALS study has been to collect single time point as well as longitudinal blood and urine samples from ALS patients and control participants for the purpose of lab measurement of toxic metals and potential ALS biomarkers such as creatinine and heat shock proteins. Subsequent statistical modelling is to be performed to determine if longitudinal trends differ in patients vs controls, to determine the prognostic importance if any of toxic metal concentrations, and to explore longitudinal heat shock proteins concentrations as biomarkers of progression in ALS.
The aim of the MetALS study has been to collect single time point as well as longitudinal blood and urine samples from ALS patients and control participants for the purpose of lab measurement of toxic metals and potential ALS biomarkers such as creatinine and heat shock proteins. Subsequent statistical modelling is to be performed to determine if longitudinal trends differ in patients vs controls, to determine the prognostic importance if any of toxic metal concentrations, and to explore longitudinal heat shock proteins concentrations as biomarkers of progression in ALS.
Work was conducted via 4 work packages. The first work package was concerned with transporting existing blood and urine samples from Ireland and Italy Ludwig Maximillian University in Munich, where trace metal concentrations, heat shock proteins, plasma creatinine, cystatin C and liver function tests were to be measured. These measurements have been completed and a dataset of the results complied. Additional funding was approved by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) in the amount of €343,000 for the purchase of an ICP-MS instrument, and an internal grant at LMU for €12,260 was secured for purchase of heat shock protein assay kits. The aim of WP2 was to recruit a further 100 case and 100 controls for longitudinal blood and urine sampling as the Covid19 pandemic interrupted recruitment. At the end of the action, 47 patients and 12 controls were recruited. However, collaborators from the German MND-Net biobank were able to provide us longitudinal samples from an additional 63 ALS patients from the German MND-Net biobank. The recruitment of patients and controls continues in Dublin beyond the formal end of the Action. Measurement of these samples is ongoing. WP3 detailed the statistical analysis of data collected in WPs 1&2. The project was managed under WP4. In the course of this work, the Fellow published 3 peer-reviewed journal articles (with 2 more under review at the time of writing), 1 preprint article, presented posters at 4 online conferences, and supported students and colleagues in statistical analyses of ongoing projects. In addition he provided formal peer review for multiple journals in the fields of neurology and environmental epidemiology.
Results of this Action will be reported in forthcoming research papers that will address 1) normative reference data for urinary metals in healthy Irish individuals, 2) a comparison of heat shock proteins between ALS patients and health controls at a single timepoint, 3) an analysis of the longitudinal trends in toxic metals and HSP’s in ALS cases versus controls, and 4) an analysis to determine if any of the metal concentrations or heat shock proteins have prognostic importance in ALS patients.
Results of this Action will be reported in forthcoming research papers that will address 1) normative reference data for urinary metals in healthy Irish individuals, 2) a comparison of heat shock proteins between ALS patients and health controls at a single timepoint, 3) an analysis of the longitudinal trends in toxic metals and HSP’s in ALS cases versus controls, and 4) an analysis to determine if any of the metal concentrations or heat shock proteins have prognostic importance in ALS patients.
The dataset collated for WP1 includes biomarker data for nine different metals in blood and urine, representing the first such dataset from an Irish cohort. This data is useful in regulatory toxicology, and EU funded human biomonitoring projects such as HBM4EU and the upcoming European partnership for the assessment of risks from chemicals (PARC) project have need for such data. When the dataset from WP2 is complete, the dataset will be complemented by longitudinal metals and heat shock protein data. This will break new ground in several ways, since longitudinal metals biomarker data in ALS patients is lacking, and since longitudinal metals biomarkers and contemporaneous heat shock protein data have not been previously measured. Thus, there are impacts anticipated for biomonitoring and regulatory toxicology and potential impact on the role of metals and/or heat shock proteins in ALS aetiology.