Host-bacterial interactions at mucosal surfaces require recognition of the bacteria by host cells enabling targeted responses to maintain tissue homeostasis. It is now well recognized that an array of host-derived pattern recognition receptors (PRRs), both cell-bound and soluble, are critical to innate immune engagement of microbes via microbial-associated molecular patterns (MAMP). This report describes the use of a nonhuman primate model to evaluate changes in the expression of these sensing molecules related to aging in healthy gingival tissues. Macaca mulatta aged 3-24 years were evaluated clinically and gingival tissues obtained, RNA isolated and microarray analysis conducted for gene expression of the sensing pattern recognition receptors (PRRs). The results demonstrated increased expression of various PRRs in healthy aging gingiva including extracellular (CD14, CD209, CLEC4E, TLR4), intracellular (NAIP, IFIH1, DAI) and soluble (PTX4, SAA1) PRRs. Selected PRRs were also correlated with both bleeding on probing (BOP) and pocket depth (PD) in the animals. These findings suggest that aged animals express altered levels of various PRRs that could affect the ability of the tissues to interact effectively with the juxtaposed microbial ecology, presumably contributing to an enhanced risk of periodontitis even in clinically healthy oral mucosal tissues with aging.
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This project was supported by National Institute of Health grants P20GM103538 and UL1TR000117, and P20GM103436. We express our gratitude to the Caribbean Primate Research Center (CPRC) supported by grant P40RR03640, and the Microarray Core of University Kentucky for their invaluable technical assistance.
Gonzalez, Octavio A.; Kirakodu, Sreenatha S.; Novak, Michael John; Stromberg, A. J.; Orraca, L.; Gonzalez-Martinez, J.; Burgos, A.; and Ebersole, Jeffrey L., "Comparative Analysis of Microbial Sensing Molecules in Mucosal Tissues with Aging" (2018). Center for Oral Health Research Faculty Publications. 17.