Characterization of the saliva proteome of patients with oral lichen planus

Abstract

Oral lichen planus (OLP), which belongs to the noninfectious oral mucosal diseases, is an inflammatory autoimmune disease that affects 0.5 - 2% of all people worldwide. The disease causes erosions and redness on the oral mucosa, which can be painful and thus limit patients' quality of life. The pathomechanism involved in the development of OLP is not completely elucidated. Saliva sample analysis through various proteomic strategies will enable a better understanding of the pathomechanism. Therefore, the aim of this study is to establish a new method for saliva sample preparation to identify potential biomarkers for OLP by applying mass spectrometry (MS) based clinical proteomics strategy. Saliva samples were pooled in defined groups (OLP patients and healthy control group) as well as prepared individually for proteomics analysis and measured by MS methods. Supernatant and pellet of saliva were examined. The analysis was performed by functional annotation and pathway analysis of the identified markers using bioinformatics tools (e.g. MaxQuant, Perseus, Statistica). A total of approximately 500 proteins were quantified. These were assigned to membrane-bound proteins and proteins originating from the extracellular space. Of the total proteins, 10% (approximately 50) were shown to be statistically associated with OLP. These are structural and inflammatory proteins and proteins involved in immune processes. The establishment of the new method for saliva sample analysis (supernatant and pellet) makes it possible to identify a higher number of proteins. This will provide information about the proteome and, inferentially, more information about changes in it. The results of the identification of the potential biomarkers for OLP, transferred to clinical application, can provide fundamental hints for the development of specific diagnostic tools. In addition to a better understanding of the pathomechanism, the use of the potential biomarkers may contribute to the development of a clinical therapy. This leads to completely new perspectives for studies with saliva samples of any kind.