Bacterial Amyloids: The Link between Bacterial Infections and Autoimmunity

Molecular mimicry is a common mechanism used by many bacteria to evade immune responses. In recent years, it has become evident that bacteria also decorate the extracellular matrix (ECM) of their biofilms with molecules that resemble those of the host. These molecules include amyloids and other proteins, polysaccharides, and extracellular DNA. Bacterial amyloids, like curli, and extracellular DNA are found in the biofilms of many species. Recent work demonstrated that curli and DNA form unique molecular structures that are recognized by the immune system, causing activation of autoimmune pathways. Although a variety of mechanisms have been suggested as the means by which infections initiate and/or exacerbate autoimmune diseases, the mechanism remains unknown. In this article, we discuss recent work on biofilms that highlight the role of amyloids as a carrier for DNA and potentiator of autoimmune responses, and we propose a novel link between bacterial infections and autoimmune diseases.