The rate of wound healing is increased in psoriasis

Abstract

Background: Psoriasis shares many features with wound healing, a process that involves switching keratinocytes from growth to differentiation. Ca2+ is known to regulate this process. The N-methyl-d-aspartate receptor (NMDAR), an ionotropic glutamate receptor found on keratinocytes, is expressed abnormally in psoriasis in vivo.

Objectives: The goals of this study are to determine whether the rate of healing in the skin of psoriatic individuals differs from that observed in normal skin and whether the keratinocyte hyperproliferation found in psoriasis correlates with expression of specific NMDAR subunits.

Methods: Three mm punch biopsies were performed on the skin of normal, as well as, involved and uninvolved skin of subjects with psoriasis. On day 0, as well as, on day 6 after the biopsy, photographs were taken and the size of the wounds determined using ImageJ. Using immunohistochemistry, the biopsy material was stained for NMDAR and its subunits.

Results: Involved and uninvolved skin of individuals with psoriasis shows significantly more rapid healing than normal. The NR2C subunit of NMDAR is down-regulated in the basal cell layer of involved and uninvolved epidermis of psoriatic subjects compared to controls. By contrast, cells in the basal cell layer of the uninvolved epidermis showed a significantly greater percent strong staining for NR2D compared to those cells in normal epidermis.

Conclusions: Wound healing is significantly accelerated in psoriasis compared to normal. Immunohistochemistry showed that the relative intensity of strong immunostaining for subunits of the NMDAR is altered in the basal cell layer in psoriatic skin compared to normal controls. We suggest that these alterations may contribute to the increased rate of wound healing in psoriasis.

Keywords: Keratinocyte proliferation; NMDA-receptor; Psoriasis; Wound healing.

Fig. 1. Measurement of Wound Healing in psoriasis and normal Skin

(a) Photographs of the sites of the biopsies at days 0 and 6 performed in normal, involved and uninvolved skin. (b) Measurement of the size of the wounds on days 0 and 6. Inserts indicate the number of subjects biopsied. The involved and uninvolved biopsies were performed on the buttock of a 23 year old female; The normal biopsy was performed on the buttock of a 26 year old female. Asterisks indicate a significant difference from normal skin.

Fig. 2. Immunohistochemical Staining

Depicted are representative histologic sections of the three different phenotypes, normal, involved and uninvolved, stained with five different antibodies (magnification 10×).

Fig. 3. Quantitation of the Staining Intensity Using Five Different Antibodies on Three Different Skin Phenotypes

The intensity of the staining expressed as percent of cells staining either strong, medium or weak is depicted for normal, involved and uninvolved skin samples. The background staining was subtracted. . Asterisks indicate a significant difference from normal skin.