Immunohistopathologic studies in the development of psoriatic lesion influenced by gamma-interferon and the producing cells

Genome-Wide Association Study of Alopecia Areata in Taiwan: The Conflict Between Individuals and Hair Follicles

Purpose

Alopecia areata (AA) is one of the most prevalent autoimmune diseases affecting humans. Given that hair follicles are immune-privileged, autoimmunity can result in disfiguring hair loss. However, the genetic basis for AA in the Taiwanese population remains unknown.

Materials and Methods

A genome-wide association study was conducted using a cohort of 408 AA cases and 8167 controls. To link variants to gene relationships, we used 882 SNPs (P<1E-05) within 74 genes that were associated with AA group to build the biological networks by IPA software. HLA diplotypes and haplotypes were analyzed using Attribute Bagging (HIBAG)-R package and chi-square analysis.

Results

Seven single nucleotide polymorphisms (SNPs) including LINC02006 (rs531166736, rs187306735), APC (rs112800832_C_CAT), SRP19 (rs139948960, rs144784670), EGFLAM (rs16903975) and LDLRAD3 (rs79874564) were closely associated with the AA phenotype (P<5E-08). Examination of biological networks revealed that these genomic areas are associated with antigen presentation signaling, B cell and T cell development, Th1 and Th2 activation pathways, Notch signaling, crosstalk signaling between dendritic cells and natural killer cells, and phagosome maturation. Based on human leukocyte antigen (HLA) genotype analysis, four HLA genotypes (HLA-B*15:01-*40:01, HLA-DQA1*01:02-*03:03, HLA-DQA1*01:02, and HLA-DQB1*02:01) were found to be associated with AA (adjusted p-value<0.05). HLA-DQA1*01:02 is the most significantly related gene in the Taiwanese population (adjusted p-value = 2.09E-05).

Conclusion

This study successfully identified susceptibility loci associated with AA in the Taiwanese population. These findings not only shed light on the origins of AA within the Taiwanese context but also contribute to a comprehensive understanding of the genetic factors influencing AA susceptibility.

The hair follicle-psoriasis axis: Shared regulatory mechanisms and therapeutic targets

It has long been known that there is a special affinity of psoriasis for the scalp: Here, it occurs most frequently, lesions terminate sharply in frontal skin beyond the hair line and are difficult to treat. Yet, surprisingly, scalp psoriasis only rarely causes alopecia, even though the pilosebaceous unit clearly is affected. Here, we systematically explore the peculiar, insufficiently investigated connection between psoriasis and growing (anagen) terminal scalp hair follicles (HFs), with emphasis on shared regulatory mechanism and therapeutic targets. Interestingly, several drugs and stressors that can trigger/aggravate psoriasis can inhibit hair growth (e.g. beta-blockers, chloroquine, carbamazepine, interferon-alpha, perceived stress). Instead, several anti-psoriatic agents can stimulate hair growth (e.g. cyclosporine, glucocorticoids, dithranol, UV irradiation), while skin/HF trauma (Köbner phenomenon/depilation) favours the development of psoriatic lesions and induces anagen in "quiescent" (telogen) HFs. On this basis, we propose two interconnected working models: (a) the existence of a bidirectional "hair follicle-psoriasis axis," along which keratinocytes of anagen scalp HFs secrete signals that favour the development and maintenance of psoriatic scalp lesions and respond to signals from these lesions, and (b) that anagen induction and psoriatic lesions share molecular "switch-on" mechanisms, which invite pharmacological targeting, once identified. Therefore, we advocate a novel, cross-fertilizing and integrative approach to psoriasis and hair research that systematically characterizes the "HF-psoriasis axis," focused on identification and therapeutic targeting of selected, shared signalling pathways in the future management of both, psoriasis and hair growth disorders.

Ultraviolet-B irradiation decreases IFN-gamma and increases IL-4 expression in psoriatic lesional skin in situ and in cultured dermal T cells derived from these lesions

Type 1 cytokine producing T cells play an important role in the pathogenesis of psoriasis. Ultraviolet-B (UVB) irradiation is effective in the treatment of this disease. In normal skin, UVB causes a change in dermal microenvironment, leading to a decrease of IFN-gamma expressing type 1 T cells and a concurrent increase of IL-4 expressing type 2 T cells. The aim of this study was to show whether UVB irradiation causes a like-wise shift of type 1 and type 2 responses in psoriatic skin. For this purpose, biopsies were obtained from the lesional skin of psoriatic patients before, 2 days and 14 days after a single exposure to 4 MED UVB. Sections from these biopsies were immunostained (CD3, IFN-gamma and IL-4) or RNA was extracted and analyzed for the expressions of IFN-gamma and IL-4 by PCR. In addition, primary cultures of T cells from dermal cell suspensions were stained intracellularly for IFN-gamma and IL-4 expression and CD4+ and CD8+ T subsets were analyzed by flow cytometry. IFN-gamma was abundantly expressed in situ before irradiation and decreased in all patients after UVB irradiation, whereas IL-4 expression was variably expressed before irradiation and increased in different degrees after irradiation. Cytokine mRNA expressions determined by PCR showed a clear decrease of IFN-gamma and increase of IL-4 following UVB irradiation. Both CD4+ and CD8+ dermal T cells were found to produce less IFN-gamma and more IL-4 following UVB irradiation as determined by flow cytometry. Decrease in IFN-gamma expression and increase in IL-4 expression of dermal T cells in psoriatic lesions after UVB irradiation may lead to decrease in local immunoreactivity. These changes could be part of the therapeutic effects of UVB on psoriasis.

Response of keratinocytes from normal and psoriatic epidermis to interferon-gamma differs in the expression of zinc-alpha(2)-glycoprotein and cathepsin D

Psoriasis is a T cell-mediated inflammatory disease characterized by hyperproliferation and by aberrant differentiation. We found cathepsin D and zinc-alpha(2)-glycoprotein, two catalytic enzymes associated with apoptosis and desquamation, to be present in the stratum corneum of the normal epidermis but absent from the psoriatic plaque. Psoriasis is characterized by an altered response to interferon-gamma (IFN-gamma), including the induction of apoptosis in normal but not in psoriatic keratinocytes, often with opposite effects on gene expression of suprabasal proteins. We found that IFN-gamma binding and signaling were attenuated in psoriasis: The IFN-gamma receptor, the signal transducer and activator of transcription STAT-1, and the interferon regulatory factor IRF-1 were strongly up-regulated by IFN-gamma in normal keratinocytes, but not in psoriatic ones. IFN-gamma strongly up-regulated the expression of the catalytic enzymes cathepsin D and zinc-alpha(2)-glycoprotein in normal keratinocytes but down-regulated them in psoriatic ones; the reverse was true of the apoptotic suppressor bcl-2. We believe that the aberrant response to IFN-gamma plays a central role in the pathophysiology of psoriasis, particularly the disruption of apoptosis and desquamation.

IL-12, Independently of IFN-γ, Plays a Crucial Role in the Pathogenesis of a Murine Psoriasis-Like Skin Disorder

The onset of acute psoriasis and the exacerbation of chronic psoriasis are often associated with a history of bacterial infection. We demonstrate that while only few scid/scid mice develop disease when CD4+CD45Rbhigh T cells are transferred alone, coadministration of LPS plus IL-12 or staphylococcal enterotoxin B into scid/scid mice 1 day after CD4+CD45Rbhigh T cell transfer greatly enhances disease penetrance and severity. Most importantly, the skin lesions induced by this method exhibit many of the histologic hallmarks observed in human psoriasis. Skin infiltrating CD4+ T cells were predominantly memory/effector cells (CD45Rblow) and exhibited a highly polarized Th1 phenotype. To test whether the development of pathogenic T cells was dependent on their production of IFN-γ, we transferred IFN-γ−/− CD4+CD45Rbhigh T cells into scid/scid or into T, B and NK cell-deficient scid/beige mice. Surprisingly, the incidence of psoriasis was similar to scid/scid animals that received IFN-γ+/+ T cells, although acanthosis of the skin was attenuated. In contrast, the development of psoriasis was abolished if anti-IL-12 mAb was administered on day 7 and 35 after T cell transfer. Skin-derived IFN-γ−/− inflammatory cells, but not cells from anti-IL-12-treated animals, secreted substantial amounts of TNF-α, suggesting that the inflammatory effect of IFN-γ−/− T cells may be partly exerted by TNF-α and that the therapeutic effect of anti-IL-12 may depend on its ability to down-regulate both TNF-α and IFN-γ. Overall, these results suggest that IL-12, independently of IFN-γ, is able to induce pathogenic, inflammatory T cells that are able to induce psoriasiform lesions in mice.

Identification and quantitation of interferon-gamma producing T cells in psoriatic lesions: localization to both CD4+ and CD8+ subsets

Interferon-gamma (IFN-gamma) produced by lesional T cell clones is critical for the induction into G1 of the cell cycle by psoriatic keratinocyte stem cells; however, direct data demonstrating psoriatic lesional T cell subset IFN-gamma expression, and quantitation at a single cell level to calculate in vivo proportions, are lacking. In this study, using flow cytometry of freshly isolated normal and psoriatic lesional T cells from keratome biopsies, we found elevated CD3+, CD4+, and CD8+ T cells in all compartments of psoriatic skin, compared with normals. Using Brefeldin A to induce short-term intracellular accumulation of IFN-gamma in T cells capable of IFN-gamma production, we found that 90% of psoriatic patients have IFN-gamma-producing T cells at a greater proportion of their CD3+ cells than normals, with a mean of 16%+/-3%, as compared with 4%+/-2% in normal epidermis (p = 0.01). Expressed as density in the tissue, the IFN-gamma+ CD3+ cell number in psoriatic epidermis was 97+/-22 per mm2 surface area, as compared with 4.4+/-1.8 per mm2 of normal epidermis (p = 0.002). Thus, the total number of IFN-gamma+CD3+ T cells in the skin of a patient with 20% involvement is estimated to be 3.9 x 10(8). CD4+ and CD8+ IFN-gamma+ T cells were both elevated in psoriatic epidermis (p = 0.04 and p = 0.008, respectively) relative to normal skin. In the dermis, only 44% of patients demonstrated a higher percentage of IFN-gamma-producing T cells than did normals (p = 0.1), possibly indicating dilution, in some patients, by fresh infiltrating T cells. Interleukin-4 was not found by a combination of flow cytometry, reverse transcriptase-polymerase chain reaction, western blot, and immunoprecipitation. In conclusion, a significant portion of lesional T cells in psoriasis are IFN-gamma producing, without interleukin-4. The increased numbers of both IFN-gamma+CD4+ and IFN-gamma+CD8+ T cells indicate that both CD4+ and CD8+ IFN-gamma+ T cells are present in appropriate anatomic locations to sustain the lesional pathology.

Potential therapeutic use of antibodies directed towards HuIFN-gamma

IFN-gamma is an important regulator of immune responses and inflammation. Studies in animal models of inflammation, autoimmunity, cancer, transplant rejection and delayed-type hypersensitivity have indicated that administration of antibodies against IFN-gamma can prevent the occurrence of diseases or alleviate disease manifestations. Therefore, it is speculated that such antibodies may have therapeutical efficacy in human diseases. Since animal-derived antibodies are immunogenic in patients several strategies are being developed in order to reduce or abolish this human anti-mouse antibody (HAMA) response. In our laboratory, we have constructed a single-chain variable fragment (scFv) derived from a mouse antibody with neutralizing potential for human IFN-gamma. A scFv consists of only variable domains tethered together by a flexible linker. The scFv was demonstrated to neutralize the antiviral activity of HuIFN-gamma in vitro and therefore might be considered as a candidate for human therapy.

Evaluation of sialyl Lewisx antigen in the skin and the sera of patients with psoriasis vulgaris

The roles of sialyl-Lewisx antigen were evaluated in the pathogenesis of psoriasis. Sialyl-Lewisx expression was investigated immunohistochemically in the epidermis of normal human skin and erythematous lesional skin of psoriasis vulgaris by avidin-biotin-peroxidase complex procedures. A few sialyl-Lewisx positive dendritic cells were detected in the epidermis of normal human skin. In 7 out of 9 cases of psoriasis vulgaris, the number of sialyl-Lewisx-positive epidermal dendritic cells increased in the erythematous lesion over the adjacent normal skin; there were no marked changes in the numbers of CD1a-positive cells in the epidermis between the two skin types. In the double immunofluorescence studies, more than half of the sialyl-Lewisx-positive epidermal cells in psoriatic erythema were stained with a monoclonal Lag antibody that specifically reacts with Birbeck granules and related structures of human Langerhans cells. Furthermore, we determined the changes in serum levels of sialyl-Lewisx antigens in patients with psoriasis. Although levels in the sera were not significantly elevated over those of controls, the increases correlated with the degree of disease activity. These findings suggest that sialyl-Lewisx antigen is possibly involved in the development of psoriasis.

Regulatory effects of gamma-interferon on IL-6 and IL-8 secretion by cultured human keratinocytes and dermal fibroblasts

Gamma-interferon (IFN-gamma) is produced by T cells and plays an important role in immunological and inflammatory processes. To determine the effects of IFN-gamma on interleukin (IL)-6 and IL-8 secretion, normal human keratinocytes (NHKs), human squamous cell carcinoma cell line (HSC-1) cells, and human dermal fibroblasts (HDFs) were incubated with 100 U/ml of recombinant (r) IFN-gamma in the presence of various stimulants. HSC-1 cells and HDFs spontaneously secreted both IL-6 and IL-8 into the culture medium. NHKs secreted detectable levels of IL-8, but not of IL-6, and IL-8 secretion increased over 20 fold by stimulation with 10 nM of phorbol 12-myristate 13-acetate (PMA). rIFN-gamma inhibited IL-8 secretion in both HSC-1 cells and PMA-stimulated NHKs. On the other hand, it enhanced IL-1 alpha- and TNF alpha-induced IL-8 secretion in NHKs. In HDFs, rIFN-gamma inhibited IL-8 secretion, but enhanced secretion of IL-6, regardless of whether they were stimulated with IL-1 alpha or PMA. These results suggest that IFN-gamma has different regulatory effects on IL-6 and IL-8 secretion in NHKs and HDFs, depending on the stimulus.

Proliferation and interferon-gamma 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-gamma 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-gamma receptor was expressed throughout the epidermis, but was unevenly distributed. The expression of the IFN-gamma 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-gamma receptor expression and TPA decreased the expression by 13%. There was no correlation between the proliferation rate and the expression of the IFN-gamma receptor. Psoriatic and healthy keratinocytes were equally well differentiated in the skin equivalents. The interferon-gamma 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.

Distribution of interferon-gamma receptors in normal and psoriatic skin

Recent data suggest that imbalances in production and secretion of cytokines, in particular interferon-gamma (IFN-gamma), may be crucial in the pathogenesis of psoriasis. In order to exert its role on target cells, IFN-gamma has to interact with a specific cell membrane receptor termed the IFN-gamma-receptor (IFN-gamma R). We studied the distribution of IFN-gamma Rs in frozen skin biopsies from 25 psoriatics and 5 normal controls with two unrelated monoclonal antibodies, and compared its distribution with that of the IFN-gamma-inducible HLADR- and ICAM-1 antigens. In normal skin, IFN-gamma Rs were restricted to the basal cell layer; weak staining was found on scattered mononuclear cells in the papillary dermis. In 13/25 active psoriatic lesions, additional suprabasal immunoreactive foci, and in 5/25 cases, diffuse immunoreactivity of the entire epidermis were seen. No striking topographical similarities between the site and number of IFN-gamma R+, HLADR+ and ICAM-1+ keratinocyte foci were observed, suggesting that cytokines other than IFN-gamma induce HLADR-antigens on psoriatic keratinocytes in vivo. The restricted distribution of IFN-gamma R on the germinative cell layer in normal skin confirms the role played by IFN-gamma in the normal growth regulation of the epidermis. The de novo suprabasal expression of IFN-gamma R in psoriasis argues against the current hypothesis that IFN-gamma R are down-regulated due to a local excess of IFN-gamma or transforming growth factor alpha (TGF-alpha). Whether IFN-gamma Rs in psoriatic skin are functionally normal and involved in signal transmission, remains to be studied.

Acute cutaneous eruptions after marrow ablation: roses by other names?

This review will cover acute cutaneous eruptions following marrow ablation in the treatment of various malignant neoplasms. The clinical and histopathological features of 1. the eruption of lymphocyte recovery, 2. acute allogeneic graft-vs-host reaction, 3. acute autologous (spontaneous) graft-vs-host reaction, 4. eruptions associated with the administration of cyclosporin A, and 5. eruptions associated with the administration of human recombinant cytokines in pharmacologic doses will be considered. The idea is put forth that the second, third, and fourth cutaneous eruptions listed above represent variations on the theme of the eruption of lymphocyte recovery. The final common pathway in the development of all these diffuse erythematous eruptions probably relates to the elaboration of cytokines by infiltrating lymphocytes or to the administration of cytokines in pharmacologic doses.