Advances in phototherapy for psoriasis and atopic dermatitis

Figures & data

Table 1. Phototherapeutical approaches for the treatment of psoriasis and atopic dermatitis.

Phototherapeutical method	Abbreviation	Spectrum (nm)
Natural phototherapy (heliotherapy)	SOLAR UV	290–3200
Broadband UVB	BB-UVB	290–320
Narrowband UVB	NB-UVB	311–313
Selective UV phototherapy	SUP	300–330
Xenon chloride excimer laser	XeCl laser	308
Xenon chloride excimer lamp	MEL	308
UVB light emitting diode	UVB-LED	310–312
Flat-type fluorescent UVB lamp	F-UVB	311–313
UVA	UVA	320–400
Mixed UVB/UVA	UVAB	300–400
Psoralen + UVA photochemotherapy	PUVA	320–400
UVA-1 phototherapy	UVA-1	340–400
Pulsed Dye laser	PDL	585/595
Nd: YAG laser	Nd: YAG	1064
Intense pulse light	IPL	535–1250/535–575
Low-level laser therapy	LLLT	400–500, 630–800

Table 2. Mechanism of action of UV phototherapy.

	UV light-proposed effects	References
TARGET CELLS	Apoptosis induction in T cells	[28–31,39]
	Apoptosis induction in keratinocytes	[32]
	Induction of regulatory T- cells	[33–35,41–43]
	Inhibition of NK cell function	[37]
	Improvement of the disturbed vasculature	[27]
	Inhibition of Langerhans cells and macrophages	[21,36]
	Inhibition of neutrophils	[38]
INTRACELLULAR EFFECTS	DNA damage	[21–24,26]
	Cell membrane damage	[21,24,25]
	Isomerization of chromophores (urocanic acid)	[21]
	Induction of cytoplasmic transcription factors	[21–24]
	Modulation of cytokine production	[39–43]

Figure 1. Mechanism of action of ultraviolet radiation in treating immune-mediated skin diseases.

Figure 2. Action spectrum of ultraviolet B (UVB) to induce intraepidermal T cell apoptosis.

The efficacy of different UVB wavelengths to induce intraepidermal apoptosis in case of (a) thin epidermis (d = 65 um from the surface of the skin), (b) moderately acanthotic epidermis (d = 140 um from the surface of the skin), or (c) severily acanthotic epidermis (d = 250 um from the skin surface). AIie is the theoretical extent of intraepidermal T cell apoptosis induction computed by multiplying the extent of in vitro T cell apoptosis induction and the percentage of transmitted UVB light at each wavelength studied, plotted on a relative scale.

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