Immunosuppressive effect of prolactin-induced protein: a new insight into its local and systemic role in chronic allergic contact dermatitis

BACKGROUND

Prolactin-induced protein (PIP) has been shown to bind to CD4 and is speculated to block CD4-HLA-DR interaction. However, the immunomodulatory effect of PIP on chronic allergic contact dermatitis (ACD) remains to be elucidated.

OBJECTIVES

To define the role of PIP during the immunoresponse.

METHODS

Using a low-dose oxazolone-induced mouse chronic ACD model, expression of PIP was examined immunohistologically. Furthermore, effects of continued exposure to a peptide mimicking the major binding site of PIP (amino acids 106-132) for CD4 was examined in a mouse chronic ACD model.

RESULTS

We clarified that keratinocytes, dermal infiltrating cells and spleen infiltrating mononuclear cells are positively stained with anti-PIP antibody. The PIP peptide significantly downregulated oxazolone-induced mouse ACD compared with controls. We also found that inflammation of the control ear, to which the PIP peptide had not been applied, was also suppressed in a synchronized manner in the late phase of ACD.

CONCLUSIONS

These findings suggest that PIP might have a local and systemic immunosuppressive effect in mouse chronic ACD.

Large-scale DNA microarray analysis of atopic skin lesions shows overexpression of an epidermal differentiation gene cluster in the alternative pathway and lack of protective gene expression in the cornified envelope

BACKGROUND

Atopic dermatitis (AD)-specific genes have not yet been clarified. Objectives To identify gene expression specific to active atopic skin lesions.

METHODS

We analysed 23,000 genes in skin biopsy samples from 17 patients with AD and four normal controls using Affymetrix oligonucleotide arrays.

RESULTS

Four of the 10 genes with the greatest differences in expression between patients and controls, S100A8 and S100A7 (upregulated), and loricrin and filaggrin (downregulated), were epidermal differentiation genes located on 1q21, a locus previously reported to have a genetic linkage with AD.

CONCLUSIONS

Our results, showing downregulation of the cornified envelope genes and upregulation of the alternative keratinization pathway, are the first to suggest abnormal epidermal differentiation and defective defences as key abnormalities in AD.