Differential expression of microRNAs let-7a, miR-125b, miR-100, and miR-21 and interaction with NF-kB pathway genes in periodontitis pathogenesis.

Periodontitis is a chronic inflammatory disease which is caused by destruction of the tissues that surrounds and supports the tooth. Deregulation of microRNAs has been reported to cause several inflammatory diseases such as autoimmune disease, chronic periodontitis, and cancer. In the present study, we have investigated the expression pattern of microRNAs let-7a, miR-125b, miR-100, miR-21, and RNA-binding protein LIN-28A among healthy individuals and chronic periodontitis patients. Total RNA was isolated from gingival tissue samples collected from 100 healthy individuals and 100 chronic periodontitis patients. The expression of microRNAs and LIN-28 was performed by qPCR. Target prediction for the microRNAs was done using miRWalk and miRTarbase online databases and the experimentally validated targets were analyzed for their molecular function, biological processes, and related pathways using gProfiler software. The expression analysis revealed that let-7a and miR-21 were upregulated, whereas, miR-100, miR-125b, and LIN-28 were down regulated. The age dependent expression analysis revealed that the expression levels of all the microRNAs and LIN-28 were found to increase with age (more than 50 years), thereby suggesting an increased risk to chronic periodontitis. Among the various targets predicted using miRWalk and miRTarbase databases, NFKB was found to be a common target among all the four microRNAs. gProfiler revealed several functions such as NF-ĸB signaling pathway, cytokine-cytokine receptor interaction, osteoclast differentiation, etc., all of which specific to inflammation and periodontitis.