Exosomes are Nano-sized lipid vesicles secreted from mammalian cells containing diverse cellular materials such as proteins, lipids, and nucleotides. Multiple lines of evidence indicate that in saliva, exosomes and their contents such as microRNAs (miRNAs) mediate numerous cellular responses upon delivery to recipient cells. The objective of this study was to characterize the different expression profile of exosomal miRNAs in saliva samples, periodically isolated from a single periodontitis patient. Unstimulated saliva was collected from a single patient over time periods for managing periodontitis. MicroRNAs extracted from each phase were investigated for the expression of exosomal miRNAs. Salivary exosomal miRNAs were analyzed using Affymetrix miRNA arrays and prediction of target genes and pathways for its different expression performed using DIANA-mirPath, a web-based, computational tool. Following the delivery of miRNA mimics (hsa-miR-4487, -4532, and -7108-5p) into human gingival fibroblasts, the expression of pro-inflammatory cytokines and activation of the MAPK pathway were evaluated through RT-PCR and western blotting. In each phase, 13 and 43 miRNAs were found to be differently expressed (|FC| ≥ 2). Among these, hsa-miR-4487 (|FC|=9.292005) and hasmiR- 4532 (|FC|=18.322697) were highly up-regulated in the clinically severe phase, whereas hsa-miR-7108-5p (|FC|= 12.20601) was strongly up-regulated in the clinically mild phase. In addition, the overexpression of miRNA mimics in human gingival fibroblasts resulted in a significant induction of IL-6 mRNA expression and p38 phosphorylation. The findings of this study established alterations in salivary exosomal miRNAs which are dependent on the severity of periodontitis and may act as potential candidates for the treatment of oral inflammatory diseases.

Introduction
 Materials and Methods
  Clinical subject and ethics statement
  Saliva collection and isolation of salivary exosomes
  Reagents
  Cell culture and transfection of miRNA mimics
  Affymetrix miRNA arrays
  MicroRNA target prediction and pathway analysis
  Reverse-transcription polymerase chain-reaction(PCR)
  Western blot
  Statistical analysis
 Results
  Clinical characteristics
  Characteristics of differentially expressed miRNAsin salivary exosomes
  Overexpression of miRNA mimics (hsa-miR-4487,-4532, and 7108-5p) in human gingival fibroblastsresults in induction of IL-6 expression and p38activation
 Discussion
 References

• Sung Nam Park(Department of Oral Physiology, and Institute of Biomaterial-Implant, Wonkwang University, School of Dentistry)
• Young Woo Son(Department of Oral Physiology, and Institute of Biomaterial-Implant, Wonkwang University, School of Dentistry)
• Eun Joo Choi(Department of Oral and Maxillofacial Surgery, College of Dentistry, Wonkwang University, Wonkwang Dental Research Institute)
• Hyung-Keun You(Department of Periodontology, School of Dentistry, Wonkwang University)
• Min Seuk Kim(Department of Oral Physiology, and Institute of Biomaterial-Implant, Wonkwang University, School of Dentistry) Correspondence to