A single intradermal injection of IFN-γ induces an inflammatory state in both non-lesional psoriatic and healthy skin

Psoriasis is a chronic, debilitating, immune-mediated inflammatory skin disease. As IFN-γ is involved in many cellular processes, including activation of dendritic cells (DCs), antigen processing and presentation, cell adhesion and trafficking, and cytokine and chemokine production, IFN-γ-producing Th1 cells were proposed to be integral to the pathogenesis of psoriasis. Recently, IFN-γ was shown to enhance IL-23 and IL-1 production by DCs and subsequently induce Th17 cells, which are important contributors to the inflammatory cascade in psoriatic lesions. To determine whether IFN-γ indeed induces the pathways expressed in psoriatic lesions, a single intradermal injection of IFN-γ was administered to an area of clinically normal, non-lesional (NL) skin of psoriasis patients and biopsies were collected 24 hours later. Although there were no visible changes in the skin, IFN-γ induced many molecular and histological features characteristic of psoriatic lesions. IFN-γ increased a number of differentially expressed genes in the skin, including many chemokines concomitant with an influx of T cells and inflammatory DCs. Furthermore, inflammatory DC products tumor necrosis factor (TNF), inducible nitric oxide synthase, IL-23, and TNF-related apoptosis-inducing ligand were present in IFN-γ-treated skin. Thus, IFN-γ, which is significantly elevated in NL skin compared with healthy skin, appears to be a key pathogenic cytokine that can induce many features of the inflammatory cascade of psoriasis.     

CIITA versus IFN-γ induced MHC class II expression in head and neck cancer cells

A growing body of evidence suggests that optimal induction of systemic anti-tumor immunity requires priming of both the CD4+ and CD8+ T cells that are specific for tumor-associated antigens (TAA). Recently, it was shown that MHC class II positive tumor cells are able to induce tumor-specific CD4+ T cells, and that this event may improve clinical outcome. This has rekindled the interest in modulating MHC class II expression in nonprofessional antigen presenting tumor cells. The class II transactivator (CIITA) is a major regulator of MHC class I and class II expression. We compared, in head and neck cancer cell lines, the effect of stable overexpression of CIITA to treatment with IFN-γ on the cell surface expression profile of MHC class I and II molecules. Here, we provide evidence that CIITA transfection is more effective than IFN-γ in inducing MHC class II expression. To more thoroughly explore the mechanisms of MHC class II induction in this context, we used RT-PCR to measure the mRNA expression pattern of HLA-DR, HLA-DM, cathepsin S, and the invariant chain. In contrast to the effect of treatment with IFN-γ, CIITA transfection did not induce cathepsin S, an important protease responsible for the degradation of the invariant chain, and thus for binding of the peptides to the MHC class II binding groove. These findings may have a significant impact on practical and clinical aspects of tumor immunotherapeutic strategies.     

Proliferation and interferon-γ receptor expression in psoriatic and healthy keratinocytes are influenced by interactions between keratinocytes and fibroblasts in a skin equivalent model

Epidermal-dermal interactions were studied in a skin equivalent model. Six combinations of keratinocytes and fibroblasts from healthy and psoriatic skin were used. TPA (12-O-tetradecanoylphorbol-13-acetate) was used to determine whether the expression of the IFN- receptors in keratinocytes was related to epidermal differentiation and proliferation. These phenomena were assessed by immunohistochemistry. In all epidermal outgrowths, the epidermal growth factor receptor was expressed throughout the epidermis, cytokeratin 16 suprabasally, and filaggrin and involucrin in its superficial part. The IFN- receptor was expressed throughout the epidermis, but was unevenly distributed. The expression of the IFN- receptor was quantified by confocal laser scanning microscopy both in the whole of epidermis and in areas with the strongest intensity. The total amount varied to a minor degree in the epidermal outgrowths of different origins and was unaffected by TPA. In high-intensity areas interactions between keratinocytes and fibroblasts did influence the amount of IFN- receptor expression and TPA decreased the expression by 13%. There was no correlation between the proliferation rate and the expression of the IFN- receptor. Psoriatic and healthy keratinocytes were equally well differentiated in the skin equivalents. The interferon- receptor was similarly expressed under these conditions. The growth rate, assessed by Ki-67-positive nuclei in the basal layer, was highest in healthy keratinocytes. Keratinocytes from psoriatic lesions increased their growth rate when cocultured with psoriatic fibroblasts compared with normal ones, indicating that fibroblasts may be of importance for epidermal hyperproliferation in psoriatic lesions.     

Screening of differentially expressed genes and predominant expression of β variable region of T cell receptor in peripheral T cells of psoriatic patients

Psoriasis is a skin disease featuring epithelial cell hyper-proliferation and T cell infiltration. Abnormal T cell immune responses play an important role in psoriatic pathogenesis. To screen differentially expressed genes in T cells of patients with plaque psoriasis, analyze the predominant expression of the β variable region of T cell receptors and discuss the role of T cells in the pathogenesis of psoriasis. High throughput RNA sequencing and Real-time PCR were used. Results: A total of 907 genes were differentially expressed in peripheral T cells of patients with psoriasis. Among them, 695 genes were mapped to the Gene Ontology database, 14 gene terms were significantly enriched, and 418 genes were involved in signaling pathways such as apoptosis, B cell receptor signaling and T cell receptor signaling. TRBV2, TRBV5-7, TRBV6-6/6-9, TRBV12, TRBV24 and TRBV29 were significantly up-regulated in psoriatic patients compared to healthy subjects, among which, TRBV6-6/6-9, TRBV12 and TRBV29 are predominantly expressed in psoriatic patients. Many genes were differentially expressed in T cells of psoriatic patients, especially the TRBV gene family, which were predominantly expressed in T cells and might play an important role in abnormal immune responses of T cells in psoriatic patients.     

In vivo levels of IL-4, IL-10, TGF-β1 and IFN-γ mRNA of the peripheral blood mononuclear cells in patients with alopecia areata in comparison to those in patients with atopic dermatitis

Alopecia areata (AA) has been considered to be supported by an aberrant expression of IFN-γ as a result of antigen dependent immune response. On the other hand, AA sometimes concurs with atopic diseases, although the mechanism of the concurrence is not clear. This study was designed to elucidate the immune status of AA and the similarity between AA and atopic dermatitis (AD) by analysis of in vivo levels of mRNA of Th1, Th2, and suppressive cytokines of peripheral blood mononuclear cells (PBMC). Using semiquantitative RT-PCR, the levels of cytokine mRNA were measured in freshly isolated PBMC of 47 patients with AA, 15 patients with AD, and 12 healthy controls (HC). The levels of IL-4, IFN-γ, and TGF-β1 mRNA were lower in patients with AA than those in HC. The levels of IL-10 mRNA in AA were comparable with those in HC. Decreased levels of IFN–γ and TGF-β1 were also shown in patients with AD. These results indicated a similarity (decreased levels of IFN-γ and TGF-β1) between AD and AA based on the cytokine profile. In addition, decreased levels of IL-4 mRNA in AA might also explain the experience that the severity of atopic disease coincident with AA is mild in the most of cases. Next, we compared the levels of these cytokine mRNA among the three subgroups of AA that were categorized based on the severity of the symptoms: mild, severe and totalis. Although there was no significant difference between any combinations of the subgroups, there was a tendency to increase the levels of IFN-γ mRNA and to decrease the levels of IL-4 mRNA according to the severity of alopecia. However, the levels of IFN-γ mRNA in any subgroups were less than those of HC. These results suggest that IFN-γ is therefore involved in the pathogenesis of AA, although the information from PBMC is limited. In conclusion, AA might be induced by an aberrant expression of IFN-γ in individuals whose PBMC produce low amounts of IFN-γ and TGF-β1. Further analysis is therefore required to investigate the phenotypes of the population in PBMC with or without reference to regulatory T cells.     

Non-M protein(s) on the cell wall and membrane of group A streptococci induce(s) IFN-γ production by dermal CD4+ T cells in psoriasis

Abstract Recently we have demonstrated that a disease-specific subpopulation of CD4⁺ T cells isolated from skin lesions of chronic plaque psoriasis produces interferon-γ in response to group A streptococcal (GAS) antigens. To determine if these T cells recognize M or non-M protein, extracts from cell wall of type M6 GAS (M6W) and its isogenic M gene deletion mutant (M-W), M6 membrane extract (M6M) and recombinant M6 protein (rM6) were used to stimulate GAS-reactive T-cell lines from nine patients with chronic plaque psoriasis. T-cell lines were incubated with or without streptococcal extracts for 18 h in the presence of a transport inhibitor, stained for surface CD4 and intracellular cytokine expression, and analysed by flow cytometry. Variable numbers (0.2–34%) of CD4⁺ T cells produced interferon-γ, in all but one of the T-cell lines tested, in response to M6W, M-W and M6M extracts. No significant difference between the response to M6W and M-W extracts was detected. In addition, rM6 protein failed to increase CD4⁺/interferon-γ⁺ T-cell numbers in seven of nine T-cell lines compared to medium alone. For the group, there was a highly significant correlation between the responses to the three extracts (M6W vs M-W, P = 0.0005; M6W vs M6M, P = 0.0003; M-W vs M6M, P = 0.0001). Low or minimal numbers of interleukin-4- and interleukin-10-producing CD4⁺ T cells were occasionally induced. These findings suggest that a subpopulation of CD4⁺ T cells isolated from skin lesions of chronic plaque psoriasis patients produces interferon-γ in response to non-M protein(s) present on the cell wall and membrane of GAS. Received: 11 September 2000 / Revised: 20 December 2000 / Accepted: 3 February 2001