Characterization of the seminal plasma proteome in men with prostatitis by mass spectrometry

Abstract

Background: Prostatitis is an inflammation of the prostate gland which affects approximately 10% of men. Despite its frequency, diagnosing prostatitis and monitoring patient response to treatment remains frustrating. As the prostate contributes a substantial percentage of proteins to seminal plasma, we hypothesized that a protein biomarker of prostatitis might be found by comparing the seminal plasma proteome of patients with and without prostatitis. Results: Using mass spectrometry, we identified 1708 proteins in the pooled seminal plasma of 5 prostatitis patients. Comparing this list to a previously published list of seminal plasma proteins in the pooled seminal plasma of 5 healthy, fertile controls yielded 1464 proteins in common, 413 found only in the control group, and 254 found only in the prostatitis group. Applying a set of criteria to this dataset, we generated a high-confidence list of 59 candidate prostatitis biomarkers, 33 of which were significantly increased in prostatitis as compared to control, and 26 of which were decreased. The candidates were analyzed using Gene Ontology and Ingenuity Pathway analysis to delineate their subcellular localizations and functions.

Multi-omics biomarker pipeline reveals elevated levels of protein-glutamine gamma-glutamyltransferase 4 in seminal plasma of prostate cancer patients

“…To facilitate our diagnostic strategy, we considered as candidates only secreted and membrane-bound proteins which were previously identified in our SP proteome of more than 3,000 proteins [20][21][22] . We assumed that some candidates selected with large-scale -omics approaches might be false-positives due to various pre-analytical, analytical and data analysis biases.…”

“…Nearly a quarter of molecular composition of SP is secreted by prostate 18,19 , with the rest produced by seminal vesicles, epididymis, testis and periurethral glands. We previously completed several years of work on proteome of SP and identified more than 3,000 proteins in SP of healthy men and patients with infertility, prostatitis and prostate cancer [20][21][22] .…”

Proteomics of human seminal plasma: Identification of biomarker candidates for fertility and infertility and the evolution of technology

“…Some of these proteins may represent non-invasive biomarkers that allow for discrimination of non-obstructive from obstructive azoospermia cases, including LDHC, ELSPBP1, CES7, A2M, OVCH2, PTGDS, GPR64, and ALDH1A1 . Kagedan et al (2012) compared the previously published list of SP proteins in the pooled sample of five healthy fertile controls from Kumar et al (2008) with the set of 1,708 proteins in the pooled sample from five patients affected by prostatitis, resulting in 1,464 proteins commonly expressed in fertile controls and in patients affected by prostatitis, 413 proteins found only in the control group, and 254 were found only in the prostatitis group. They created a high-confidence list of 59 candidate prostatitis biomarkers, 33 of which were significantly elevated in prostatitis patients when matched to control, and 26 of which were decreased.…”

“…In recent years, multi-dimensional approaches have been proposed for the study of complex protein mixtures, such as SP, coupling highly sensitive and specific separation techniques to MS instruments (Drake et al, 2010;Batruch et al, 2011;Kagedan et al, 2012). For example, 2D gel electrophoretic separation followed by identification with either MALDI-TOF MS or capillary LC-MS/MS was used to visualize the whole seminal proteome, from which over 100 protein and peptide components of normal human seminal fluid were identified (Fung et al, 2004).…”

“…The flight time of each ionized fragment is proportional to the square root of the m/z ratio. As the charge (z) of the ionized proteins is often þ1, the m/z value is often equal to the mass (2003) MALDI-TOF Impaired spermatogenesis Utleg et al (2003) LCMS/MS Prostasome Fung et al (2004) MALDI-TOF; LC-MS/MS Healthy fertile men Pilch and Mann (2006) MALDI-TOF; LTQ-FT Healthy fertile man Yang et al (2007) SELDI-TOF Biomarkers of oligospermia Yamakawa et al (2007) LCMS/MS Infertile versus fertile men Bai et al (2008) SELDI-TOF Severe oligospermia versus healthy fertile men Kumar et al (2008) MALDI-TOF Heparin binding proteins in human seminal plasma Kumar et al (2009) MALDI-TOF Heparin binding proteins in human seminal plasma Wang et al (2009) LCMS/MS Asthenozoospermia Drake et al (2010) LTQ-Orbitrap XL Prostatic secretions Batruch et al (2011) LTQ-Orbitrap XL Post-vasectomy versus healthy fertile men Milardi et al (2012b) LTQ-Orbitrap XL Healthy fertile men Batruch et al (2012) LTQ-Orbitrap XL Non-obstructive azoospermia Kagedan et al (2012) LTQ-Orbitrap XL Prostatitis Molecular Reproduction & Development value. The spectral output produced by MALDI-TOF is represented by a number of protein peaks, which are described by a m/z value on the horizontal axis and by a peak-intensity value on the vertical axis (Schuchardt and Sickmann, 2007).…”