Arteriosclerosis: The Novel Finding of Biofilms and Innate Immune System Activity within the Plaques

Abstract

Atherosclerosis (AS) is a chronic disorder characterized by the formation and progression of plaques within arteries. Various microbes, most notably periodontal organisms, have been identified in plaques both epidemiologically and microbiologically, and have been deemed possible contributors to the disease. In this work, we have queried whether microbes acted similarly in AS, when compared to other chronic diseases such as atopic dermatitis, psoriasis, and Alzheimer’s disease, by making biofilms to protect themselves and evade the immune system. In those diseases, the microbes created biofilms that activated the innate immune system reactant Toll-like receptor 2 (TLR2). We examined 12 endarterectomy specimens using probes similar to those used in our previous examinations of the above diseases. Specifically, we stained the pathology specimens with hematoxylin and eosin (H+E), and periodic acid Schiff (PAS); the PAS stain would reveal the extracellular polysaccharides that forms the mass of the biofilm. Congo red, which stains the amyloid that forms the infrastructure of biofilms, was also performed. Immunostaining with CD 282 was performed on each specimen for evaluation of TLR 2. Twelve of twelve atherosclerotic plaques showed the presence of biofilms and activation of TLR 2; this is entirely similar to our findings in atopic dermatitis, psoriasis and Alzheimer’s disease. The TLR 2 seen in the specimens suggests that biofilms in atherosclerotic plaques may contribute to the progression of the disease as a result of their ability to contribute to chronic inflammation and continued immune system activation. Lipids have long been considered to be the major focus of atherosclerosis, but our recent work suggests that biofilms, due to their ability to induce a chronic inflammatory state, may be another determinant in the progression of atherosclerosis. In the future, we hope to characterize the microbes-with an initial focus on periodontal microbes because of the calcification in the plaques-that directly contribute to biofilm formation and propagation.