Epithelial Cell / Epithelium

Epithelial tissues line the outer surfaces of organs and blood vessels and the inner surfaces of cavities in many internal organs.

Epithelium of the outermost layer of the skin is the epidermis.

Lung epithelial cells have a lot of PRRs

Barrier epithelial tissues of skin, lung, and intestine are the first line of defense against external assaults. Upon infection, these epithelia often sense pathogen-associated molecular patterns (PAMPs), such as ‘‘non-self’’ bacterial DNA or viral RNA, which activate pattern recognition receptors and downstream interferon response transcription factors (IRFs) to promote induction and secretion of type-I and -III interferons (IFNs)
Akira et al. 2006 Cell 124: 783–801
Constant et al. 2021 Curr Opin Immunol 73: 1-8

Epithelial surfaces sustain diverse communities of commensals that include bacteria, archaea, fungi, protozoa and viruses
Eckburg et al. 2003
Reyes et al. 2010
Foulongne et al. 2012
Grice & Segre 2012
Iliev et al. 2012 Science. 336: 1314–1317

see also:
Interleukin-24 (IL-24)