Comparative Analysis of the Proteomic Profile of the Dental Pulp in Different Conditions. A Pilot Study

Abstract

This study aimed to quantitatively compare the difference in protein expression in the progression of pulp pathogenesis, as well as to describe the biological functions of proteins identified in pulp tissue. Samples were obtained from six patients treated at the Araçatuba School of Dentistry and were divided into three groups: normal pulp - from teeth extracted for orthodontic indication; inflamed pulp and necrotic pulp - from patients diagnosed with irreversible pulpitis and chronic apical periodontitis, respectively. After previous proteomic preparation, dental pulp samples were processed for label-free quantitative proteomic analysis in a nanoACQUITY UPLC-Xevo QTof MS system. The difference in expression between the groups was calculated using the Protein Lynx Global Service software using the Monte Carlo algorithm. A total of 465 human proteins were identified in all groups. The most expressed proteins in the inflamed pulp group in relation to the normal pulp group were hemoglobin, peroxiredoxins and immunoglobulins, whereas the less expressed were the tubulins. Expression levels of albumins, immunoglobulins and alpha-2-macroglobulin were higher in the necrotic pulp group than in the inflamed pulp group. As for the qualitative analysis, the most prevalent protein functions in the normal pulp group were metabolic and energetic pathways; in the inflamed pulp group: cellular communication and signal transduction; and regulation and repair of DNA/RNA, while in the necrotic pulp group proteins were associated with the immune response. Thus, proteomic analysis showed quantitative and qualitative differences in protein expression in different types of pulp conditions.

Quantitative proteomic analysis in symptomatic and asymptomatic apical periodontitis

“…The methodology of proteomic analysis used in this study was previously tested and validated by a pilot study that analysed qualitatively and quantitatively human proteins differently expressed in normal, inflamed and necrotic pulp tissue (Loureiro et al . 2020). The sample preparation protocol was adapted from the study of Ventura et al .…”

“…This protocol used allowed the identification of 124 human proteins in the group involving necrotic pulp on the pilot study, which were classified according to their biological function in order to understand the pathogen–host relationship in the progression of pulp diseases (Loureiro et al . 2020). The comparison between the necrotic group of the pilot study and the asymptomatic group of the present report revealed that despite the different number of proteins, which is related to the different sample sizes, there was a proximity of the biological functions of the groups of proteins, especially in the immune response.…”

“…(2008) and Loureiro et al . (2020). The endodontic clinical procedures were performed by an endodontist (CL).…”

“…The collection was conducted according to the protocol previously described by Jacinto et al (2008) and Loureiro et al (2020). The endodontic clinical procedures were performed by an endodontist (CL).…”

“…More recently, a quantitative approach was used to describe the proteomic changes in the progression of endodontic pathogenesis, allowing a more accurate interpretation of the host inflammatory response by comparing the protein expression of normal, inflamed and necrotic pulp tissues (Loureiro et al . 2020). To date, however, no study has quantitatively compared the protein expression of symptomatic and asymptomatic AP, in order to determine the biological function of these proteins within the complex pathogen–host relationship.…”