Table 1.

Source and known function of Th17-related cytokines.

Cytokine	Cell Producers	Played Roles	Mechanism of Action
IL-17A, IL-17F	Th17	Mucosal protection	Increases bacterial elimination	[53,54]
			Induces claudin, mucin production	[14,63]
		Gastric inflammation	Recruitment of neutrophils	[74,82,83]
			Synergize with IFNγ & IL-8	[8,76,79]
		Progression of ulcer	Increases mucosal damages	[71]
		Progression of gastric cancer	Expression of angiogenic factors	[84]
			Promotes cancer cells’ growth	[85]
		Exacerbation of colitis	Increases chemokine	[36,70]
			Recruitment of neutrophil	[32,51]
IL-21	Th17, Th1, Tfh, NK,	Promotion to inflammation	Maintains Th17 and Th1 proliferation	[42]
			Induces CCL20	[70,86]
		Induction of H. pylori-specific antibodies	Autocrine loop of Tfh cell	[87]
			Drives B cell to produce antibodies	[88,89]
		ECM degradation	Induces MMPs	[11]
IL-23	Macrophage, DCs, neutrophil	Promotion to inflammation	Maintains Th17 and Th1 proliferation	[66,67,90]
			Recruitment of neutrophils	[14,82]