TABLE 1.

Expression levels of SCFAs in different inflammatory skin diseases.

Disease	Age	SCFAs involved							Samples	Expression levels (compared to normal)	Association with disease	Ref.
		C2	C3	C4	iC4	C5	iC5	iC6
AD	0∼3 Y	√	√	√		√			Feces	C4↓, C5↓		Park et al., 2020
	3∼12 M	√	√	√					Feces	C2↓, C3↓, C4↓	The reduction in butyrate and propionate levels was significantly associated with AD.	Ta et al., 2020
		√	√	√					Feces	C3↓, C4↓		Song et al., 2016
Eczema	Infant	√	√	√		√			Feces	C4↓, C5↓	Butyrate and valerate levels were negatively correlated with SCORAD at 12 months of age.	Kang M. J. et al., 2021
	Infants	√	√	√	√				Feces	C3↑, C4↑ at 12 weeks. This pattern was reversed at 26 weeks with C3↓ and C4↓	Butyrate and valerate levels were negatively correlated with eczema.	Wopereis et al., 2018
	Infants	√	√	√					Feces	C2↓, C4↓		Kim H. K. et al., 2015
	Children	√	√	√	√	√	√	√	Feces	C5↓	The level of fecal valerate at 1 year of age was inversely associated with eczema at 13 years of age.	Batta et al., 2021
	Children	√	√	√	√	√			Feces		The expression level of valerate was negatively correlated with the incidence rate of eczema.	Gio-Batta et al., 2020
CSU	12∼60 Y				√				Feces	iC4↓		Wang et al., 2021
	18∼75 Y			√					Feces and blood	C4 metabolism↓	Lower butyrate levels due to dysregulation of the gut microbiota may play an important role in the pathogenesis of CSU.	Wang et al., 2020
Psoriasis		√	√		√	√			Blood	iC4↑, C5↑, C2↓, C3↓		Khyshiktuev et al., 2008

AD, atopic dermatitis; C2, acetate; C3, propionate; C4, butyrate; i-C4, iso-butyrate; C5, valerate; i-C5, iso-valerate; i-C6, iso-caproate; CSU, chronic spontaneous urticaria; HDACi, histone deacetylases inhibition; M, months old; Y, years old; Ref., references; SCORAD, scoring of atopic dermatitis.