Gamma delta T-cell receptor-positive cells in human skin. I. Incidence and V-region gene expression in granulomatous skin lesions

Dominance and improved survivability of human γδT17 cell subset aggravates the immunopathogenesis of pemphigus vulgaris

Human γδ T cells are highly enriched in epithelial cell-dominated compartments like skin. Nonetheless, their function in the pathogenesis of pemphigus vulgaris (PV), an autoimmune skin disorder, is lacking. Therefore, we investigated the functional expression of human γδT cell subsets along with their homing chemokine receptor-ligand and inflammatory cytokines in the immunopathogenesis of PV. Estimation of the frequency of γδT cell subsets by flow cytometry revealed four major subsets of γδ T cells (γδT1, γδT2, γδT17, γδTreg) in both control and PV circulation. The elevated frequency of γδT17 cells producing IL17 and expressing CCR6 receptor suggests their inflammatory and migratory potential in PV. In vitro culture of γδ T cells from patients showed increased mRNA expression of inflammatory cytokines IL17, RORγt, IL23, IL1, and co-stimulatory markers, CD27 and CD70. These findings correlated the role of IL1 and IL23 cytokines that alleviate the Th17 population in PV. Cytotoxic activities of γδ T cells were higher and inflammatory γδT17 cells were localized in the skin of PV whereas γδTreg cells associated TGFβ and FOXP3 were lowered. Hyperinflammatory phenotype of the γδT17 cell subset and its migratory potential might be aiding in the pathogenesis of PV, whereas γδTreg cells fail to suppress these inflammatory responses. Hence, γδT17 cell-associated markers can be targeted for identifying novel therapeutics in PV.

Innate Lymphocyte Mechanisms in Skin Diseases

Innate lymphocyte populations are emerging as key effectors in tissue homeostasis, microbial defense, and inflammatory skin disease. The cells are evolutionarily ancient and carry conserved principles of function, which can be achieved through shared or unique specific mechanisms. Recent technological and treatment advances have provided insight into heterogeneity within and between individuals and species. Similar pathways can extend through to adaptive lymphocytes, which softens the margins with innate lymphocyte populations and allows investigation of nonredundant pathways of immunity and inflammation that might be amenable to therapeutic intervention. Here, we review advances in understanding of innate lymphocyte biology with a focus on skin disease and the roles of commensal and pathogen responses and tissue homeostasis.

T helper type 1 polarizing γδ T cells and Scavenger receptors contribute to the pathogenesis of Pemphigus vulgaris

γδ T cells and Scavenger receptors are key parts of the innate immune machinery, playing significant roles in regulating immune homeostasis at the epithelial surface. The roles of these immune components are not yet characterized for the autoimmune skin disorder Pemphigus vulgaris (PV). Phenotyping and frequency of γδ T cells estimated by flow cytometry have shown increased frequency of γδ T cells (6·7% versus 4·4%) producing interferon- γ (IFN-γ; 35·2% versus 26·68%) in the circulation of patients compared with controls. Dual cytokine-secreting (IFN-γ and interleukin-4) γδ T cells indicate the plasticity of these cells. The γδ T cells of patients with PV have shown higher cytotoxic potential and the higher frequency of γδ T cells producing IFN-γ shows T helper type 1 polarization. The increased expression of Scavenger receptors expression (CD36 and CD163) could be contributing to the elevated inflammatory environment and immune imbalance in this disease. Targeting the inflammatory γδ T cells and Scavenger receptors may pave the way for novel therapeutics.

Lymphocyctes Tgammadelta in clinically normal skin and peripheral blood of patients with systemic lupus erythematosus and their correlation with disease activity

Human Tgammadelta lymphocytes constitute from 1 to 15% of all peripheral blood lymphocytes. Recent work has demonstrated that this population plays a major role in the pathogenesis of infectious and immune diseases. Increased numbers of gammadelta T cells have been found in affected skin from systemic sclerosis and chronic cutaneous lupus erythematosus patients. In our study, we have determined the numbers of Tgammadelta lymphocytes and their subpopulations in peripheral blood from 29 patients with systemic lupus erythematosus (SLE) and in 19 healthy volunteers using flow cytometry and specific monoclonal antibodies. The same cells in uninvolved skin from SLE patients and human controls using immunohistochemical analysis were estimated. T-Cell receptor (TCR) delta chain gene rearrangement was identified with primers for Vdelta1, Vdelta2 and Vdelta3 by the polymerase chain reaction. Statistical analysis showed a significantly decreased number of gammadelta T cells in SLE patients (26.4+/-16.9/microl) compared with the control group (55.3+/-20.6/microl (p < 0.001). The number of Vdelta2 TCR+ and Vgamma9 TCR+ subpopulations was also lower in SLE patients than in healthy persons. No statistical correlation between disease activity and the number of gammadelta T cells was demonstrated. The percentage of Tgammadelta lymphocytes in clinically normal skin from SLE patients was twice (22.0+/-9.4%) that found in the skin from healthy persons (11.1+/-5.5%) (p < 0.002). Higher percentages of the Vdelta2 TCR+ and Vgamma9 TCR+ subpopulation of lymphocytes were found in the skin from SLE patients. We have also found positive correlation between the percentage of Tgammadelta lymphocytes in skin and the activity of SLE (r=0.594, p < 0.001), and between subpopulation Vdelta3 TCR+ and disease activity (r=0.659, p< 0.001). In conclusion, the results of our studies demonstrate that, in patients with SLE, accumulation of Tgammadelta lymphocytes can be seen in clinically normal skin, and the percentage of these cells correlates with the activity of the disease.

The TCR-delta repertoire in normal human skin is restricted and distinct from the TCR-delta repertoire in the peripheral blood

The skin and the intestinal mucosa form surfaces to external environments and share similarities in anatomic structure and immunologic defense. In healthy humans, intestinal gamma/delta T cells express a highly restricted gamma/delta T cell receptor repertoire whereas gamma/delta T cells of the skin were thought to express a polyclonal repertoire. Herein we report, using complementarity-determining region 3 size spectratyping and nucleotide sequencing of T cell receptor DV1 and DV2 rearrangements, that the human skin is also composed of clonally expanded gamma/delta T cells that are widely distributed. Identical complementarity-determining region 3 profiles and T cell receptor delta rearrangements were found in two separate skin samples that were obtained as far as 2-10 cm apart. Furthermore, analysis of peripheral blood mononuclear cells of these subjects clearly demonstrated that the skin harbors a unique population of gamma/delta T cells that is distinct from that in the peripheral blood. In addition comparable data were obtained irrespective of whether DNA or RNA was analyzed, indicating that the observed oligoclonality is not secondary to the expression of large amounts of mRNA from a few activated cells. Thus, gamma/delta T cells of the skin and the intestine both express an oligoclonal repertoire that enables them to respond to a variety of deleterious antigens without the need for diverse T cell receptors, possibly by recognition of stress-induced self-antigens or of conserved foreign antigens.

Expression of 27 KD, 65 KD and 72/73 KD heat shock protein in atopic dermatitis: comparison with those in normal skin and contact dermatitis

The expression of Heat Shock Protein (HPS) 72/73, HSP65 and HSP27 in skin lesions of atopic dermatitis (n = 21) was studied and compared with that in contact dermatitis (n = 18) and normal skin (n = 9). Keratinocytes in the whole epidermis expressed both HSP65 and HSP72/73 with a membranous, cytoplasmic or nuclear/perinuclear staining pattern much more intensely in atopic dermatitis than in contact dermatitis and normal subjects. In approximately half of the subjects with atopic dermatitis, infiltrating cells in the dermis expressed HSP65 and HSP72/73; this was not observed in contact dermatitis. HSP27 was expressed in the upper epidermis with a cytoplasmic or nuclear/perinuclear staining pattern in all groups. HSP27 was not expressed by infiltrating cells. A clinical evaluation of atopic dermatitis showed that more severe types of atopic dermatitis expressed more intense expression of HSP65 and HSP72/73, but not HSP27, in their skin lesions. These findings suggested that HSP65 and HSP72/73 may play roles in the pathogenesis of atopic dermatitis.

The histopathologic spectrum of erythema induratum of Bazin

Erythema induratum of Bazin is a tuberculid that is strongly associated with tuberculosis. Clinically, erythema induratum of Bazin show recurrent tender subcutaneous nodules that occur mainly on the calves of women with tuberculin hypersensitivity. Previous studies have not documented the histopathologic spectrum of erythema induratum of Bazin in detail. We identified two major histopathologic groups in 19 of 20 skin biopsies obtained from 20 patients with well-documented erythema induratum of Bazin. Six cases (group I) showed focal septolobular panniculitis in close association with a single muscular artery or small vessel with primary neutrophilic vasculitis. Thirteen cases (group II) revealed diffuse septolobular panniculitis with primary neutrophilic vasculitis of either large or smaller vessels. Both groups showed varying combinations and degrees of acute and chronic inflammation, coagulative and caseation-like necrosis, and granulomatous inflammation. Poorly developed granulomas predominated, but mixed, palisading, and lipophagic granulomas also occurred. Inflammation and necrosis were more extensive in group II. Erythema induratum of Bazin may show predominantly acute suppurative or granulomatous panniculitis. Immunostaining showed S100+ antigen-presenting cells, macrophages, and T-lymphocytes. B-lymphocytes were rare. The presence of primary vasculitis and granulomas suggests that types III and IV hypersensitivity reactions play a role in the pathogenesis or erythema induratum of Bazin. The latter remains a clinicopathologic diagnosis, but awareness of the heterogeneous histopathologic spectrum of EIB will ensure a timely diagnosis and institution of antituberculous treatment.

Epidermal expression of 65 and 72 kd heat shock proteins in psoriasis and AIDS-associated psoriasiform dermatitis

BACKGROUND

Psoriasiform dermatitis is common in patients with AIDS. The expression of heat shock proteins by keratinocytes has been postulated to be a significant factor in the physiopathology of psoriasis and might be subject to modulation in HIV-infected patients.

OBJECTIVE

We sought to evaluate the epidermal expression of 65 and 72 kd heat shock proteins (HSPs) in lesions of AIDS-associated psoriasiform dermatitis (AIDS-PD) and compare it with that in psoriasis vulgaris and seborrheic dermatitis in patients not infected with HIV.

METHODS

Sections from paraffin-embedded blocks of biopsy specimens of AIDS-PD (eight cases), psoriasis vulgaris (eight cases), seborrheic dermatitis (four cases), and normal skin (four cases) in non-HIV-infected patients were immunohistochemically stained by the avidin-biotin-peroxidase method and two monoclonal antibodies directed against the major 65 kd HSP antigen (HSP65) and against 70/72 kd HSP. The intensity, distribution, and cellular pattern of the epidermal stain were graded and assessed blindly.

RESULTS

The epidermal expression of HSP65 in biopsy specimens from AIDS-PD lesions was irregular, with less intensity and less tendency to perinuclear arrangement than in psoriasis or seborrheic dermatitis not associated with AIDS. The expression of HSP72 was also less intense and more uniform in AIDS-PD.

CONCLUSION

The altered interplay of T cells and keratinocytes in a situation of immune derangement such as AIDS might account for the differences observed in the expression of HSP65 and HSP72 by keratinocytes in psoriasis and AIDS-PD.

Characteristics of HPRT-mutant T cell lines in a lupus patient treated with cyclophosphamide

This report describes T cell lines derived from a patient with subacute cutaneous lupus after treatment with intravenous pulse cyclophosphamide. We selected for mitotically active, hypoxanthine-guanine phosphoribosyltransferase-deficient (HPRT-) T cells, by culture in a selective medium containing 6-thioguanine. When HPRT- cell lines were derived 6 days after pulse cyclophosphamide (CYC) treatment, they were predominantly CD8+ and T cell receptor (TCR) gamma/delta+, producing interferon-gamma (IFN gamma). Cell lines derived 21 days after CYC treatment were CD4+, TCR alpha/beta+ and produced both IFN gamma and interleukin-4. These results support a possible role for gamma/delta+ T cells in subacute cutaneous lupus and suggest a mechanism for the therapeutic effect of CYC.

gamma delta T-cell receptor-positive cells of human skin. II. Appearance in delayed-type hypersensitivity reaction

In order to investigate the distribution and involvement of human gamma delta T-cell receptor-positive (TCR+) cells in delayed-type hypersensitivity reactions of the skin, we examined the occurrence and kinetics of gamma delta TCR+ cells during skin reactions of allergic contact dermatitis. In normal human skin sections, gamma delta TCR+ cells were scarce. In allergic contact dermatitis from DNCB, increased gamma delta TCR+ cells were observed both in the epidermis and in the dermis from 48 h after the challenge. Most of the gamma delta TCR+ cells were TCR delta 1+ delta TCS1- BB3+ Ti gamma A+ (V delta 1- V delta 2+ V gamma 9+). The percentage of gamma delta TCR+ cells in the peripheral blood remained unchanged and a few gamma delta TCR+ cells in the skin lesions proliferated in situ. It is suggested that the gamma delta TCR+ cells in skin lesions of allergic contact dermatitis may not be involved in initiation of delayed-type hypersensitivity but may have some other roles responding to factors induced in the reaction.