Table II.

Function and mechanisms of inflammatory factors in the regulation of melanogenesis.

Factor	Experimental cells	Effect on melanogenesis	Mechanisms	(Refs.)
IL-18	Keratinocyte	Promotion	Increasing tyrosinase activity and upregulating TYRP-1 and TYRP-2 expression	(43)
IL-33	Melanocytes	Promotion	Promoting MITF, TYR, TYRP-1, TYRP-2 expression by activating the p38/MAPK and PKA pathways	(14)
GM-CSF	Melanocytes	Promotion	Promoting melanocyte proliferation and melanin synthesis	(17)
PGE2 and PGF2α	Keratinocytes	Promotion	Stimulating melanocyte dendrite formation through a cAMP-dependent pathway	(62)
IFN-γ	B16F10	Inhibition	Blocking maturation of melanosome and upregulating STAT1 phosphorylation	(46,72)
TNF	Melanocytes, primary pooled human keratinocytes	Inhibition	Inhibiting melanin formation through PKA and MAPK signaling pathways in combination with IL-17	(10)
IL-1α	Primary melanocytes, swine skin	Promotion	Combination of KGF increases melanin deposition	(79)
IL-1β	Melanoma cell lines (LB2259-MEL and CP50-MEL)	Inhibition	Downregulating MITF-M expression through NF-κB and JNK pathways	(74)
IL-4	Melanocytes	Inhibition	Downregulating the expression of MITF, TYRP-1, TYRP-2 through the JAK2-STAT6 signaling pathway	(13)
IL-6	Melanocytes	Inhibition	Decreasing tyrosinase activity	(12)
IL-17	Melanocytes, primary pooled human keratinocytes	Inhibition	Inhibiting melanin formation through PKA and MAPK signaling pathways in combination with TNF	(10)

TYRP-1, tyrosinase-related protein-1; TYRP-2, tyrosinase-related protein-2; MITF, microphthalmia-associated transcription factor; TYR, tyrosinase; PKA, protein kinase A; MAPK, mitogen activated protein kinase; JNK, c-Jun N-terminal kinase; JAK-STAT, Janus kinase-signal transducer and activator of transcription.