Periodontitis: a host mediated disruption of microbial homeostasis

Purpose of Review In a prolific scientific career, Dr. Robert J. Genco dedicated himself to enriching our understanding of the pathogenesis of periodontitis. During a period of time in the 1970s and 1980s, when periodontitis was considered a classic infectious disease, Bob had the foresight to investigate and characterize the immune/inflammatory response in periodontitis, particularly juvenile periodontitis. His leadership in this area brought to the fore our appreciation of host-microbial interactions that many years later (2008) culminated in the realization that periodontitis is a fundamental inflammatory disease. In this review, the question of how the host regulates the inflammatory response will be addressed in the context of how more recently discovered pathways of resolution of inflammation play a role in disease pathogenesis. Recent Findings The host inflammatory response to commensal organisms creates excess inflammation in susceptible individuals and likely drives the dysbiosis of the oral microbiome observed in people with periodontitis. In periodontal health, the oral microbiome is in balance with the host response. It is the loss of this symbiotic relationship with excess inflammation and microbiome dysbiosis that characterizes progressive diseases. In recent years, the role of mediators of inflammation resolution in the loss of balance and their potential use as therapeutics to restore homeostasis have extended our knowledge of how the host drives immune responses to affect oral dysbiosis. Summary Dr. Genco provided the foundation for our ever-emerging understanding of host-microbial interactions. The discovery of inflammation resolution pathways has furthered our knowledge in periodontal homeostasis. More studies are needed to understand how the host regulates the microbiome to fulfill the ultimate goal of more efficient therapeutics for periodontitis and related inflammatory diseases.