What is passing through toll gate 4: lipids or infection?

In this issue of the journal, Zhou and colleagues reported that hyperlipidemia might play a role in the expression of pro-inflammatory cytokines such as TNF-α and IL-1β which are associated with type 2 diabetes (T2D) and periodontitis. Not only hyperlipidemia but many obesity-related conditions such as hyperglycemia, insulin resistance, and metabolic syndrome are perceived as "threats" or as a "danger" by the innate immune system and express these cytokines. T2D is one of these conditions that elicit metabolic inflammation (meta-inflammation) and the hallmark of meta-inflammation is low grade inflammation. In addition, T2D and periodontitis are strongly correlated to each other and to innate immunity. This creates a confounding relationship. The dental research community is now required to acknowledge the concept that infection is not the only trigger for innate immune activation. The review by Zhou et al. may be the first step in the right direction to establish the orthogonal contribution of oral infection independent of meta-inflammation.