Periodontitis and lipopolysaccharides: How far have we understood?

Periodontitis is a ubiquitous chronic inflammatory worldwide disease. The multiplicity of gram-negative microbiomes and their endotoxins, such as lipopolysaccharides (LPS), play a crucial role in its pathogenesis. The detection and consequent effects of LPS occur either via membrane-based cluster of differentiation 14 (CD14)/myeloid differentiation factor 2 (MD2)/Toll-like receptor (TLR)-4 complex activation or through intracellular cytosolic LPS detection that further cascades its effects, resulting in a variety of cell death processes, including apoptosis, pyroptosis, necroptosis, NETosis, and their crosstalk. Irrespective of the detection of LPS, the cellular response is for protecting and resolving the inflammation. However, chronic and exaggerated responses in periodontitis result in the destruction of periodontal structures. This review summarizes the extracellular and cytosolic detection of LPS and its further consequences. Then, it sheds light on methods reported to mitigate the adverse effects of LPS.