Quantitative proteomics for molecular diagnostics of public health: the quest for biomarkers of infectious disease

Proteomics is well established within clinical analysis with a range of biomarkers recognised by the FDA, most of these are biomarkers of cancer [1]. Analysis of prostate specific antigen (PSA) in serum is now a routine part of prostate cancer diagnosis, where it is used alongside digital examination to determine the need for invasive prostate biopsies. The use of proteomics for investigating public health has been reported [2], where the inflammation biomarker C-reactive protein (CRP) was quantified in the urine of ~8600 study participants (10% of surveyed population) using nephelometry. Whilst an excellent study it required the analysis of approximately 58,000 urine and 8600 serum samples, where as if the same study was performed using wastewater a single representative sample could have been collected for the whole population. Analysis of pharmaceuticals and drugs of abuse as part of wastewater-based epidemiology (WWBE) is becoming well established [3], however there is still scope for expansion particularly into examining the relationship between public health and disease. We have developed a method for the analysis of proteins of disease using liquid chromatography coupled with mass spectrometry, using instruments similar to those already used for the analysis of small molecule biomarkers in WWBE [3]. To allow for this the protein biomarkers are initially digested using enzymes to form peptides, which are characteristic for their respective proteins. These characteristic peptides are then analysed using hydrophilic interaction liquid chromatography and either a triple quadrupole or quadrupole-time of flight instrument, with the dual instrument approach allowing for both biomarker quantification and for future retrospective biomarker analysis. The current analytical focus is on clinically recognised proteins of either general health, mainly inflammation, or proteins of cancer, focussing on prostate cancer. By pursuing this methodology we hope to achieve broad applicability with techniques currently used for the analysis of small molecules, and allow for easy uptake of protein analysis within the wider WWBE community.

1. Fuzery, A.K., et al., Translation of proteomic biomarkers into FDA approved cancer diagnostics: issues and challenges. Clinical proteomics, 2013. 10(1): p. 13-13. 2. Stuveling, E.M., et al., C-reactive protein is associated with renal function abnormalities in a non-diabetic population. Kidney International, 2003. 63(2): p. 654-661. 3. Ort, C., et al., Spatial differences and temporal changes in illicit drug use in Europe quantified by wastewater analysis. Addiction, 2014. 109(8): p. 1338-1352.