A comparative proteomic study of human skin suction blister fluid from healthy individuals using immunodepletion and iTRAQ labeling

Aberrations in skin morphology and functionality can cause acute and chronic skin-related diseases that are the focus of dermatological research. Mechanically induced skin suction blister fluid may serve as a potential, alternative human body fluid for quantitative mass spectrometry (MS)-based proteomics in order to assist in the understanding of the mechanisms and causes underlying skin-related diseases. The combination of abundant-protein removal with iTRAQ technology and multidimensional fractionation techniques improved the number of identified protein groups. A relative comparison of a cohort of 8 healthy volunteers was thus recruited in order to assess the net variability encountered in a healthy scenario. The technology enabled the identification, to date, of the highest number of reported protein groups (739) with concomitant relative quantitative data for over 90% of all proteins with high reproducibility and accuracy. The use of iTRAQ 8-plex resulted in a 66% decrease in protein identifications but, despite this, provided valuable insight into interindividual differences of the healthy control samples. The geometric mean ratio was close to 1 with 95% of all ratios ranging between 0.45 and 2.05 and a calculated mean coefficient of variation of 15.8%, indicating a lower biological variance than that reported for plasma or urine. By applying a multistep sample processing, the obtained sensitivity and accuracy of quantitative MS analysis demonstrates the prospective value of the approach in future research into skin diseases.