Table 1.

The most common aberrant expressed miRNAs in autoimmune and inflammatory skin diseases and their potential function.

miRNA	Level	Diseases	Sample	Potential Effects	References
miR-31	↑	psoriasis	skin lesions, serum	enhances the production of inflammatory mediators and leukocyte chemotaxis to the skin, hyperproliferation of keratinocytes, acanthosis	[7,16,17,18]
	↑	hidradenitis suppurativa	skin lesions		[108]
miR-21	↑	psoriasis	skin lesions	maintains skin inflammation, activation of T cells, stimulates keratinocyte proliferation, inflammatory cascade, and inhibition of apoptosis	[22,23,24]
	↑	hidradenitis suppurativa	skin lesions		[108]
	↓	vitiligo	peripheral blood mononuclear cells	protects melanocytes via targeting STAT3 and modulating Treg/Teff balance to alleviate vitiligo	[81]
miR-146a	↑	psoriasis	skin lesions	regulates inflammation and the proliferation of keratinocytes, inhibiting the innate immune response, controls nuclear-factor-kappa-B-dependent inflammatory responses in keratinocytes and chronic skin inflammation in AD	[18,27,28]
	↑	atopic dermatitis	skin lesions, serum		[47,48]
	↑	oral lichen planus	mucosal lesions		[102]
	↑	hidradenitis suppurativa	skin lesions	effects on TRAF6/IRAK-1 and inhibition of TNF-alpha production	[108,112]
miR-155	↑	psoriasis	skin lesions, peripheral blood mononuclear cells	modulates the differentiation and function of Th17 cells, regulates keratinocyte proliferation and differentiation, apoptotic processes, inflammatory response (overexpression of TNF-alpha, increasing infiltration with Th17 cells)	[37,38,39,40]
	↑	atopic dermatitis	skin lesions, serum		[51,53]
	↑	oral lichen planus	mucosal lesions		[103]
	↑	hidradenitis suppurativa	skin lesions		[114,115]
	↑	vitiligo	skin lesions	inhibits genes involved in melanocyte differentiation, activation of JAK-STAT	[73]
	↑	pemphigus	skin lesions	unknown	[125]
miR-203	↑	psoriasis	skin lesions	plays a significant role in keratinocyte differentiation and proliferation	[32,33]
		children atopic dermatitis	serum		[67]
		cutaneous lichen planus	skin lesions		[99]
miR-125b	↓	psoriasis	skin lesions	inhibits TNF-alpha, regulating the differentiation and proliferation of keratinocytes through its inhibitory effect on the fibroblast growth factor receptor 2 (FGFR2)	[18,42]
	↓	hidradenitis suppurativa	skin lesions		[108,118]
miR-24	↑	atopic dermatitis	serum	inhibits interferon gamma expression	[64]
	↓	hidradenitis suppurativa	peripheral blood leukocytes		[112]
miR-223	↑	atopic dermatitis	serum	relates to platelet activation and plasma TARC levels	[62,63]
	↑	hidradenitis suppurativa	skin lesions	negatively affects the proliferation of progenitors and the differentiation and activation of granulocytes	[121,122]
miR-338-3p	↓	hidradenitis suppurativa	peripheral blood leukocytes	-	[112]
	↑	pemphigus vulgaris	peripheral blood mononuclear cells	has an impact on dysfunction of Treg	[126]

Arrows indicate significant up- or downregulation of microRNA expression (↑—upregulated; ↓—downregulated).