The repertoire of T cell antigen receptor beta-chain variable regions associated with psoriasis vulgaris

[Treatment of psoriasis using biologics]

Psoriasis is a chronic inflammatory skin disease, which is characterized by red, scaly, raised plaques. Its symptoms may range in severity and there are severe clinical subtypes of psoriasis including pustular psoriasis. Pre-biological systemic therapies were targeting mainly keratinocyte proliferation and T cell activation. However, there were cases, in which these classic therapies were not fully effective or could not be used because of the accompanied severe organ failure of the psoriasis patient. Recent progress in psoriasis research has clarified which of the cells, cell surface molecules and cytokines play a pivotal role in the pathogenesis of psoriasis. Biological systemic therapies targeting these molecules have turned out to be extremely effective in treating psoriasis and are now used to treat moderate to severe psoriasis worldwide. These biological therapies are not only more effective than pre-biological systemic therapies, but also show more rapid response, and long-term efficacy is expected. The TNF-alpha inhibitors are now approved as the first biological therapy for psoriasis in Japan. These TNF-alpha inhibitors are expected to be a new standard therapy for severe psoriasis, however, since the long-term safety is an unsolved issue, careful clinical monitoring is required. (193 words).

Prevalence of genetically defined tumor cells in CD7 as well as CD26 positive and negative circulating T-cell subsets in Sézary syndrome

For diagnosis and monitoring of Sézary syndrome flow cytometric quantification of CD7- and CD26- T-cells is widely used. Because antigen loss is a characteristic but not disease-specific finding we investigated the significance of this approach. Therefore we analyzed the prevalence of tumor cells in FACS-sorted CD7+/- as well as CD26+/- circulating T-cells applying a clone-specific qualitative and quantitative T-cell receptor PCR. Tumor cells varied considerably in the CD7+ and CD7- cell subset but were largely confined to the CD26- population. We conclude that quantification of CD26- T-cells reflects the tumor cell amount more accurate and should be preferred in the clinical setting.

Decreased T-Cell Receptor Excision Circles in Cutaneous T-Cell Lymphoma

PURPOSE

The T cell repertoire in patients with advanced cutaneous T cell lymphoma (CTCL) is significantly contracted despite the presence of relatively normal absolute numbers of T cells. We propose that many normal T cells were being lost in patients with CTCL, with the remaining normal T cells expanding clonally to fill the T cell compartment. T-cell receptor excision circles (TREC) form as a result of the initial gene rearrangement in naïve T cells. Although they are stable, they do not replicate and are subsequently diluted with the expansion of a population of T cells. Their concentration is therefore a measure of unexpanded naïve T cells relative to T cells that have undergone expansion.

EXPERIMENTAL DESIGN

We analyzed TRECs from unfractionated peripheral blood T cells from 108 CTCL patients by quantitative PCR. In patients with obvious peripheral blood involvement, we also analyzed TRECs from clonal and nonclonal T cells.

RESULTS

We found a decrease in the number of TRECs in peripheral blood of patients with CTCL at all stages of disease, and this decrease was proportional to the loss of complexity of the T cell repertoire as measured by complementarity-determining region 3 spectratyping. In patients with leukemic CTCL and a numerically expanded clone, we also found a significantly lower-than-expected number of TRECs in the nonclonal normal T cells.

CONCLUSIONS

We hypothesize that the nonmalignant T cells have proliferated to fill the empty T cell repertoire space left by the loss of other T cells, leading to diminished TRECs and loss of T-cell receptor diversity.

Immunopathogenesis of psoriasis: Recent insights on the role of adaptive and innate immunity

Psoriasis is a frequent chronic inflammatory disorder involving mostly skin and joints. Its characteristic features in the skin consist of inflammatory changes in both dermis and epidermis, with abnormal keratinocytic differentiation and proliferation. In recent years, an important set of knowledge has been provided by works addressing the immunopathogenic mechanisms of the disease. Indeed, recent advances in the knowledge of mechanisms linking innate and adaptive immunity have led to reconsideration of the roles of key players in the pathogenesis of the disease. This review will focus on results from studies performed in vitro and in vivo in patients with psoriasis, and on lessons from recently designed animal models which are considered as the most relevant with respect to the human disease. Even more important, these insights provide a rational basis for the design of new therapeutic strategies aiming at the deletion or the down regulation of activated T cells, or at the suppression of pathogenic cytokines such as TNF-alpha. Some of these new biotherapeutic tools have been successfully used in vivo in clinical trials, providing a confirmation of such concepts.

Correlation of psoriasis activity with abundance of CD25+CD8+ T cells: conditions for cloning T cells from psoriatic plaques

The role of T cells in the pathogenesis of psoriasis is widely acknowledged. However, key aspects of their precise function in the disease as well as the relative pathogenic contribution of T-cell subsets are still unknown. T-cell clones have been isolated from psoriatic plaques but a study of conditions affecting the isolation and expansion of T-cell clones from psoriatic skin has not been reported to date. Here, we observe a correlation of disease activity with the frequency of the CD3(+)CD8(+)CD25(+) subset. We show that prolonged in vitro culture changes the phenotypic subset distribution of T-cell lines derived from psoriatic skin and that T-cell clones can be isolated by sorting of CD25(+) cells emigrated from skin fragments after 7 days. We evaluate various conditions affecting expansion of psoriatic T-cell clones in vitro and show that blocking apoptosis can facilitate proliferation of activated T-cell clones in vitro. Our results indicate a prominent role of the CD8(+)CD25(+) T-cell subset in disease pathogenesis and should be useful in the design of experiments aiming at a systematic analysis of the specificity of clones present in psoriatic plaques.

Profound loss of T-cell receptor repertoire complexity in cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is a malignancy of skin-homing T cells. A major feature of CTCL is profound immunosuppression, such that patients with advanced mycosis fungoides or Sézary syndrome have been compared with patients with advanced HIV disease and are susceptible to opportunistic infection. The etiology of this immunosuppression is unclear. We analyzed peripheral blood T cells of patients with CTCL with stage I to IV disease, using a sensitive beta-variable complementarity-determining region 3 spectratyping approach. Our data revealed a profound disruption of the complexity of the T-cell repertoire, which was universally observed in patients with advanced disease (stages III and IV), and present in up to 50% of patients with early-stage disease (stages I and II). In most patients, multiple monoclonal and oligoclonal complementarity-determining region 3 (CDR3) spectratype patterns in many different beta-variable families were seen. Equally striking was a reduction of normal T cells (as judged by absolute CD4 counts) across multiple beta-variable families. In general, CTCL spectratypes were reminiscent of advanced HIV spectratypes published elsewhere. Taken together, these data are most consistent with a global assault on the T-cell repertoire in patients with CTCL, a process that can be observed even in early-stage disease.

T cell receptor Beta chain gene usage in endemic pemphigus foliaceus (fogo selvagem)

The trimolecular complex comprised of the major histocompatibility complex, peptide antigen, and the T cell receptor is a requisite for T cell activation in normal and autoimmune responses. T cell receptor analysis is critical to further our understanding regarding mechanisms of T cell epitope selection and autoimmune initiation and progression and may help to identify targets for immunotherapy. Pemphigus foliaceus is an autoimmune blistering skin disease characterized by intraepidermal blisters and circulating autoantibodies directed against desmoglein 1, a 160 kDa transmembrane desmosomal molecule expressed in keratinocytes. As tissue damage is mediated by anti-desmoglein 1 antibodies, an initial T cell response is a likely requirement for autoantibody generation in this disease. To elucidate the role of pathogenic T cells in autoimmunity further, we have directly characterized the T cell receptor of T cells derived from pemphigus foliaceus patients. Complementary DNA was isolated from 17 desmoglein 1 specific T cell clones generated from pemphigus foliaceus patients by clonal expansion in vitro. To analyze the T cell repertoire, a panel of primers, collectively specific for the known human T cell receptor beta variable region (TCRBV) families were paired with a constant region primer to polymerase chain reaction to amplify one distinct T cell receptor beta variable region allele for each T cell clone studied. Polymerase chain reaction products were sequenced to determine exact beta chain gene usage. In the 17 clones tested, 10 distinct T cell receptor beta variable region usages and nine T cell receptor beta joining gene segment usages were identified. Furthermore, T cell receptor beta variable region and beta joining usage did not appear to be random, but oligoclonal in nature, with some preference shown for T cell receptor beta variable region 5S1 and T cell receptor BJ2S5.

Delayed-type hypersensitivity reaction to paraphenylenediamine is mediated by 2 different pathways of antigen recognition by specific alphabeta human T-cell clones

BACKGROUND

Allergic contact dermatitis to paraphenylenediamine (PPD) is a frequent cause of morbidity and occupational disability.

OBJECTIVE

The aim of the study was to characterize T-cell responses to PPD and Bandrowski's base (BB), an autoxidation product of PPD, by using polyclonal and monoclonal T-lymphocyte cultures.

METHODS

PPD- and BB-driven proliferation of PBMCs and T-cell clones (TCCs) was assessed by means of tritiated thymidine incorporation. Surface markers were studied by means of flow cytometry, and cytokine generation was assessed with an ELISA.

RESULTS

TCCs, with one exception, were CD4+/CD45RO+, and T-cell receptors were alphabeta+. Three of 6 TCCs expressed Vbeta 16. TCC stimulation was HLA-DP restricted, and TCCs secreted IL-4, IL-5, and marginal levels of IFN-gamma. TCCs reacted to both PPD and BB. Presentation of BB to TCCs was dependent on viable antigen-presenting cells (APCs) pulsed for 4 hours, and fixed APCs failed to stimulate TCCs. Moreover, polyclonal responses to BB were enhanced by metabolically active enzymes, such as cytochrome P450 enzymes. BB has to be metabolized and processed. In contrast, fixation of APCs did not impair their ability to present PPD to TCC, whereas pulsing of APCs with PPD failed to stimulate TCCs. Thus PPD had to be present during the process, and polyclonal stimulation was not enhanced by cytochromes.

CONCLUSION

These results suggest that PPD itself can be recognized by T cells through a processing-independent pathway, whereas its autoxidation product, BB, required processing and possibly metabolism to stimulate the same TCC. Our data demonstrate that 2 distinct pathways of antigen presentation to activate specific TCCs are involved in the immune response to PPD.

Oligoclonal expansion of intraepidermal T cells in psoriasis skin lesions

CD8(+) T cell infiltration into the epidermis is thought to be a key event in the pathogenesis of psoriasis. A quantitative competitive polymerase chain reaction method was developed to examine the expression of T cell receptor beta chain variable region 2, 3, 6.1-3, 8, and 13.1 genes in the epidermis of psoriatic lesions. Paired epidermal samples and peripheral blood samples from five psoriasis patients were studied. The results demonstrated the expansion of T cell receptor beta chain variable region 3 (two patients), 8 (two patients), and/or 2 (one patient). Contrary to previous reports, neither beta chain variable region 6.1-3 nor beta chain variable region 13.1 subgroups were expanded in any of the lesions. DNA sequence analysis revealed dominant T cell clones observed in all expanded beta chain variable region families and heterogeneous populations and/or small clones observed in non-expanded beta chain variable region families. Using CDR3 length analysis to examine the complete beta chain repertoire of the infiltrating T cells in the lesional epidermis, we found that approximately 50% of the T cell receptor beta chain variable region families in each patient's lesion demonstrated abnormal CDR3 DNA length distribution, indicating the presence of monoclonal or oligoclonal T cell expansion. Together, the results show that among different patients, T cell oligoclonality is not restricted to a limited number of T cell receptor beta chain variable region families. In an attempt to identify the pathogenic T cells among the many expanded T cell clones in the lesions, we compared T cell receptor expansion in the lesional epidermis with non-lesional epidermis. Particular T cell receptor were found to be preferentially expanded in lesional epidermis and these lesion-specific T cell clones may be most important in the pathogenesis and development of psoriatic lesions.

Disease mechanisms in psoriasis and psoriatic arthritis

Any hypothesis that tries to explain disease mechanisms in psoriasis and psoriatic arthritis (PsA) must take into account the containment of the inflammatory process to three specific sites: the skin, synovium, and enthesis. This article reviews the recent literature that advances our understanding of disease mechanisms at these specific sites. Additional progress will be achieved by research that focuses on common pathogenic pathways at these sites, in particular when searching for foreign candidates or auto-antigens triggering the T-cell-mediated immune response.

Incidence of Candida in psoriasis--a study on the fungal flora of psoriatic patients

The presence of Candida albicans and other Candida species in saliva and faeces of 50 psoriatic patients compared with a control group of 50 healthy donors was examined quantitatively. The quantity of Candida in saliva and faeces of the psoriatics proved to be significantly higher than in the controls. Candida was detected in 78% of the saliva samples of the psoriatics but in only 50% of the controls, and in the faeces samples in 72% of the psoriatics, but in only 46% of the controls. Qualitative analysis revealed a predominance of Candida albicans (saliva, 77%; faeces, 64%) and Candida rugosa (saliva, 28%; faeces, 28%). We did not find a correlation between the severity of the psoriasis according to the Psoriasis Area and Severity Index and the amount of Candida in the saliva or in the faeces. Our results reinforce the hypothesis that C. albicans is one of the triggers to both exacerbation and persistence of psoriasis. We propose that in psoriatics with a significant quantity of Candida in faeces, an antifungal treatment should be considered as an adjuvant treatment of psoriasis.

Superantigens and autoimmune disease: are they involved?

In over 10 years since the definition of superantigens, much has been learned about host cell-superantigen interactions. The initial simple set of rules used to define these interactions has given way to a more complex system, in which the activation of multiple cell types can occur as a consequence of superantigen-cell interactions or as a result of bystander effects based on the induction of a specific cytokine milieu. As a consequence, our ideas concerning the ways in which superantigens might be involved in disease are also expanding rapidly. This review highlights some of the many different pathways of superantigen-associated pathogenesis currently under investigation.

Biased TCR Repertoire in Infiltrating Lesional T Cells in Human Bancroftian Filariasis

To investigate the hypothesis that T cells recognizing specific Ags localize to the site of disease activity in human bancroftian filariasis, we have compared the repertoire of TCR Vβ gene segments in lesions vs blood in individual patients by RT-PCR ELISA. Vβ14 and Vβ24 were overrepresented (5% greater in tissue compared with PBMCs and/or tissue/PBMC ratios in the highest 5% of all tissue/PBMC ratios for all Vβs for all subjects) in 50% and 40% of study subjects, respectively. Overrepresentation of these two Vβs did not occur in any control subject. In comparing three patient groups, the proportion of individuals meeting at least one criterion for Vβ14 overrepresentation was shown to increase in tandem with our current concepts of disease progression (asymptomatic filariasis = 25%; clinical filariasis with active infection = 60%; clinical filariasis without active infection = 71%). In 6 of the 10 individuals with Vβ14 overrepresentation, Vβ14 represented >20% of the entire lesional Vβ repertoire. All but one of the 20 study subjects had at least one Vβ gene segment that was overrepresented in tissue compared with PBMCs. Only a small number of Vβs, usually three or less, were overrepresented in any single filariasis patient. However, in the same tissue, no differences between patient groups were found when IFN-γ, TNF-α, IL-4, IL-5, and IL-12 mRNA expression were examined. Taken together, these findings suggest that, in principle, in essentially all patients, whether with subclinical or with clinical filariasis, distinct and limited T cell populations are concentrated in affected tissue.

Quantitative analysis of T-cell receptor beta variable-gene usage in cutaneous late-phase reactions: implications for T-lymphocyte recruitment in cutaneous inflammation

To determine if functionally distinct T-lymphocyte (T cell) subsets accumulate in late-phase immunoglobulin E-mediated reactions (LPR), we quantitatively analyzed the immunophenotype and the T-cell receptor beta variable-gene (Vbeta) repertoire of T cells in cutaneous LPR. Peripheral blood and skin biopsies were obtained 6 or 24 h after sensitive subjects were challenged with intradermal injections of grass pollen allergen (Ag) and control (C) solution. The frequency of cells expressing CD3, CD4, CD8, CD45RO, and CD25/mm2 was determined by immunohistochemistry in nine subjects. Vbeta usage was assessed by reverse transcription-PCR in five of nine subjects. A significantly greater frequency of CD3(+) and CD45RO+ (memory) T cells was detected in Ag sites than in C sites at 24 h after challenge but not at 6 h. The frequency of activated (CD25(+)) and helper (CD4(+)) T cells appeared to be increased in Ag sites as well, though not significantly. Vbeta6 was the most commonly expressed Vbeta detected in Ag sites, but it was also detected in accompanying C sites. Vbeta2 was the most commonly expressed Vbeta detected in C sites. Sequence analysis in one case revealed Vbeta expression in a 6-h Ag site to be essentially polyclonal. Our findings suggest that memory T cells with Vbeta expression similar to that in normal skin accumulate in developing cutaneous LPR. The limited usage of Vbeta suggests a preferential recruitment or retention of reactive T cells from an endogenous subset of skin-homing T cells with its own skewed Vbeta repertoire.

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.

Candida is not involved in the development of of periungual psoriatic lesion

Infection can be a trigger or an aggravating factor in psoriasis, and in particular, bacterial focal infection is well documented to exacerbate psoriasis presumably through its superantigen. Since fungi could produce superantigen as well, and periungual involvement is often seen in psoriatic patients, we examined if local Candida infection plays some pathogenetic role or not in periungual lesions. In 15 psoriatic patients with periungual involvement, Candida infection was examined by microscopic study, culture, and antifungal treatment. We found no evidence suggestive of the relationship between Candida and psoriatic changes in periungual area.

Psoriasis: A possible reservoir for human papillomavirus type 5, the virus associated with skin carcinomas of epidermodysplasia verruciformis

Recent polymerase chain reaction data have shown that most human papillomavirus (HPV) genotypes associated with epidermodysplasia verruciformis (EV) are widespread; however, HPV5 associated with EV skin carcinomas has only rarely been detected in non-EV patients. To identify the reservoir of this virus, we examined 335 sera from different groups of patients for the presence of HPV5 antibodies by an enzyme-linked immunosorbent assay test based on HPV5 virus-like particles. The prevalence of antibodies reacting with HPV5 virus-like particles was found to be significantly higher in psoriatic patients (24.5%) than in other groups (2-5%), including patients with atopic dermatitis and renal transplant recipients. Analysis of scrapings of lesional and uninvolved skin by a nested polymerase chain reaction method, using degenerate EV HPV primers, disclosed HPV DNA in 91.7% of 48 psoriatic skin samples and 35.5% of 31 atopic dermatitis specimens. Eleven EV HPV genotypes, most frequently HPV5 and HPV36, and a putative novel genotype (PsoX1) were identified in psoriasis. Five EV HPV genotypes and two putative novel genotypes (ADX1 and ADX2) were detected in atopic dermatitis patients. HPV5 was not found in atopic dermatitis patients. Using type specific primers, HPV5, HPV36, and HPV1 were found in 89.4%, 84.2%, and 42.1% of specimens from psoriatic patients, whereas HPV36 was detected in 22.5% of specimens from atopic dermatitis patients. HPV16 was never detected. On the whole, 27 HPV5 and 13 HPV36 DNA variants were disclosed after sequencing amplification products. Our data confirm that EV HPV are widespread and point to psoriasis as a reservoir for HPV5. Whether HPV5 is involved in the pathogenesis of psoriasis remains to be determined.

Treatment of recalcitrant plaque psoriasis with a humanized non-depleting antibody to CD4

The presence of activated CD4(+) T lymphocytes in psoriatic skin plaques suggests an immune-mediated pathogenesis for the disease. Six patients with recalcitrant plaque psoriasis (PASI>12) received a humanized non-depleting monoclonal antibody to CD4 (ORTHOCLONE OKT(R)cdr4a). The antibody was well tolerated. Four weeks from treatment, the mean decrease in PASI score was 46%. In three patients disease remission was prolonged for up to 6 months and, in one case, up to 1 year post-treatment. In all patients, circulating CD4+ T-cell counts remained normal and peripheral OKTcdr4a-coated CD4+ lymphocytes were detected up to 10 days after antibody infusion. These results point to the relevance of CD4+ lymphocytes in psoriasis. They also emphasize that depletion of CD4+ cells is not mandatory to achieve therapeutic effectiveness.