Innate lymphoid cells (ILCs) are a recently discovered type of innate immune lymphocyte. They include three different groups classified by the nature of the transcription factors required for their development and by the cytokines they produce. ILCs mainly reside in tissues close to the mucosal barrier such as the respiratory and gastrointestinal tracts. Due to their close proximity to the mucosal surface, ILCs are exposed to a variety of both commensal and pathogenic bacteria. Under non-pathological conditions, ILCs have been shown to be important regulators for the maintenance of tissue homeostasis by mutual interactions with the microbiome. Besides these important functions at homeostasis, several studies have also provided emerging evidence that ILCs contribute to defense against pathogenic bacterial infection by responding rapidly to the pathogens as well as orchestrating other immune cells. In this review, we summarize recent advances in our understanding of the interactions of ILCs and bacteria, with special focus on the function of the different ILC subsets in bacterial infections.

Background Gastrointestinal (GI) motility originates from the complex coordination of smooth muscle contraction and relaxation. GI diseases affecting motility are often associated with impaired nitrergic signaling. In the enteric nervous systems, NO is released from nitrergic neurons as a major inhibitory neurotransmitter. NO acts via NO-sensitive guanylyl cyclase (NO-GC) in different GI cell types such as smooth muscle cells (SMC) and interstitial cells of Cajal (ICC). The precise mechanism of nitrergic signaling through these two cell types to regulate colonic spontaneous contractions is not fully understood yet.