Cytokine loops involving interferon-gamma and IP-10, a cytokine chemotactic for CD4+ lymphocytes: an explanation for the epidermotropism of cutaneous T-cell lymphoma?

Human interferon-gamma (IFN-gamma)-inducible protein 10 (IP-10), a C-X-C chemokine, is secreted by IFN-gamma-stimulated keratinocytes and is chemotactic for CD4+ lymphocytes. We therefore investigated its role in the epidermotropism of cutaneous T-cell lymphoma (CTCL) that is known to express IFN-gamma mRNA in the epidermis and is characterized by an indolent course with multiple relapses that remain confined to the skin for many years. By injecting purified recombinant (r) IP-10 we generated a polyclonal rabbit antiserum that specifically recognized and neutralized rIP-10. With immunoperoxidase staining, IP-10 expression was limited to the basal epidermal keratinocytes of normal skin. In biopsies of CTCL lesions the expression of IP-10 was markedly increased and it extended to the suprabasal keratinocytes in 17 of 18 patients, but it was detectable only faintly in the dermal or epidermal lymphoid infiltrates in 2 of these 18 patients. In 1 patient who had matching biopsies performed before and after treatment, IP-10 was overexpressed before treatment, but was normally expressed in the posttreatment biopsy that showed resolution of the CTCL. Increased IP-10 expression was not detected in any of 4 patients with B-cell lymphoma involving the dermis. On the basis of these findings and a review of the literature, we propose that secretion of IFN-gamma by the lymphoid infiltrate in CTCL induces the epidermal keratinocytes to secrete IP-10 that, in turn, is chemotactic for CTCL, accounting for its epidermotropism. This model may be used as a basis for future investigations of the pathogenesis of CTCL.

Autoantibodies in Parry-Romberg syndrome: a serologic study of 14 patients.

OBJECTIVE: To determine autoantibody profiles of patients with Parry-Romberg syndrome (PRS). METHODS: Antinuclear antibodies (ANA) in 14 patients with PRS were studied by indirect immunofluorescence (IIF), immunodiffusion and immunoblotting. Antinative DNA antibodies and rheumatoid factor (RF) were also analyzed. RESULTS: ANA were positive in 8 patients (57%). The patterns of staining included nucleolar, nuclear speckled and homogeneous. Anticentromere antibodies were observed in 2 and antihistone antibodies in 3 sera. Rheumatoid factor was found in 5 (36%) sera. Antinative DNA or antibodies that precipitated rabbit thymus extract were not found in any patients. CONCLUSION: The serologic abnormalities observed in this study suggests that autoimmunity could play a pathogenic role in PRS.

Response of psoriasis to a new topical retinoid, AGN 190168.

BACKGROUND: Oral retinoids have been widely used in psoriasis, but topical forms have been ineffective or irritating. OBJECTIVE: Our purpose was to determine the clinical and molecular effects of a new topical retinoid, AGN 190168, on psoriasis. METHODS: Seven patients with psoriasis were treated for 2 weeks with topical retinoid and 2 weeks with vehicle. Two control subjects with psoriasis were treated for 2 weeks with vehicle alone. Biopsy specimens from normal skin as well as from untreated and treated psoriatic lesions were compared by immunohistochemical analysis. Differentiation and inflammatory markers were studied. RESULTS: Clinical improvement was seen in all seven patients after 2 weeks of treatment. Improvement was still present, but not significant, after 2 additional weeks of vehicle application. Histologic examination showed a return to a more normal morphology in four of seven biopsy specimens, which correlated with filaggrin expression. There was a diminution in the precocious expression of keratinocyte transglutaminase, keratin 16, and involucrin, as well as a decrease in epidermal growth factor receptor and in the number of cells expressing intercellular adhesion molecule type 1 and HLA-DR. CONCLUSION: Clinical and histologic improvements were seen in psoriasis in association with the topical application of AGN 190168 at 2 weeks, including decreased inflammation and restoration of normal epidermal differentiation. Small patient numbers and the possibility that the changes were related to clinical improvement alone and not the topical agent preclude definitive conclusions.

Keratinocyte transglutaminase expression varies in squamous cell carcinomas.

Type I transglutaminase (TGase I, keratinocyte or particulate transglutaminase) is a 92-kilodalton (kDa) protein expressed in abundance in cultured keratinocytes and in the hyperproliferative skin disorder psoriasis. To determine the expression of TGase I protein and mRNA, we studied tissue and established squamous carcinoma lines derived from different sources. Immunohistochemistry and Western blotting were used to detect TGase I protein with the B.C1 mouse monoclonal antibody. Only well-differentiated, skin-derived squamous carcinomas stained for TGase I. However, a precocious pattern of expression was seen overlying less-differentiated tumors. Compared to cultured human keratinocytes, squamous cell carcinoma (SCC) had many times less to 7.8 times more TGase I protein, greatest in the two most differentiated tumor lines 14-83 and ME-180. TGase I mRNA levels ranged from 0.010 to 0.00004 pg/microgram total RNA by reverse transcriptase-polymerase chain reaction using an internal standard. Protein expression correlated with mRNA levels in most SCC lines. When a human TGase I promoter was isolated and used to study genomic DNA, SCC1-83 was shown to have unique restriction enzyme fragments, including one indicative of methylation differences, also present within DNA from the KB line. These studies suggest that transcriptional control of TGase I gene expression in squamous carcinomas may be influenced both by cis elements in the promoter and by the degree of tumor squamous differentiation.