CD14 and infection: Moreover, since CD14 is a multifunctional co-receptor of several immune cell types (Zanoni and Granucci, 2013) and type 1 pili are expressed not only by pathogenic but also by non-pathogenic E. coli (Shawki and McCole, 2017; Croxen and Finlay, 1999), our findings add a new layer of complexity to the physiological relevance of type 1 pili – as modulators of the immune response in general and specifically during persistent and recurring infections.