Identifying Diagnostic Biomarkers: Gene Expression Profiling Leptin in Dental Pulp Tissue

Recent studies emphasized the role of leptin/leptin receptor (LEP/LEPR) in normal and inflammatory conditions of dental pulp tissues. LEP/LEPR activity is linked to potential immunomodulation responses during bacterial-induced inflammatory conditions. Additionally, there is substantial association of LEP in dental pulp stem cells (DPSCs), odontoblast differentiation/function and mineralization processes. The objective of this study is to investigate differential leptin gene expression in hypoxic (inflammatory) conditions. DPSCs were isolated from healthy adult third molars, supplemented with 1% serum containing media or osteogenic media, and cultured in hypoxic (3%) or normoxic (21%) conditions for 21-days. Later, DPSCs collected were extracted for mRNA isolation. The mRNA was sequenced using NextSeq Illumina and was analyzed using the ERGO transcription tool DESeq2 (P<0.05) statistical method to determine differences in transcription and subsequent translation between groups. The count data was imported into R-package for analysis and sequence mapping to the appropriate gene. The genes and pathways were identified in KEGG pathways overlaying expression values. Over-expressed (p<0.05) genes include ACSL1, LEP, LEPR and PRKAA2 and under-expressed (p<0.05) genes include MAPK8, NFKBIE, RELA. DPSCs in hypoxic conditions shows down-regulation of AMPK signaling, which is related to cellular energy, transcription factors p65, NF-kappa-B and MAP Kinases associated with transcription regulation and differentiation. Up regulation of LEP/LEPR is associated with fat metabolism and both immune and inflammatory responses. Therefore, LEP signaling is an important regulator of DPSCs function. Furthermore, deciphering LEP/MAPK/Insulin signaling pathways in inflammatory condition of dental pulp could lead to new and more effective treatments for pulpitis and apical periodontitis.