Accumulation of γδ Cells in Chronic Cutaneous Lupus Erythematosus

Recent advances in cutaneous lupus

Cutaneous lupus erythematosus (CLE) is an inflammatory and autoimmune skin condition that affects patients with systemic lupus erythematosus (SLE) and exists as an isolated entity without associated SLE. Flares of CLE, often triggered by exposure to ultraviolet (UV) light result in lost productivity and poor quality of life for patients and can be associated with trigger of systemic inflammation. In the past 10 years, the knowledge of CLE etiopathogenesis has grown, leading to promising targets for better therapies. Development of lesions likely begins in a pro-inflammatory epidermis, conditioned by excess type I interferon (IFN) production to undergo increased cell death and inflammatory cytokine production after UV light exposure. The reasons for this inflammatory predisposition are not well-understood, but may be an early event, as ANA + patients without criteria for autoimmune disease exhibit similar (although less robust) findings. Non-lesional skin of SLE patients also exhibits increased innate immune cell infiltration, conditioned by excess IFNs to release pro-inflammatory cytokines, and potentially increase activation of the adaptive immune system. Plasmacytoid dendritic cells are also found in non-lesional skin and may contribute to type I IFN production, although this finding is now being questioned by new data. Once the inflammatory cycle begins, lesional infiltration by numerous other cell populations ensues, including IFN-educated T cells. The heterogeneity amongst lesional CLE subtypes isn't fully understood, but B cells appear to discriminate discoid lupus erythematosus from other subtypes. Continued discovery will provide novel targets for additional therapeutic pursuits. This review will comprehensively discuss the contributions of tissue-specific and immune cell populations to the initiation and propagation of disease.

Associations of lymphocyte subpopulations with clinical phenotypes and long-term outcomes in juvenile-onset systemic lupus erythematosus

OBJECTIVE

Juvenile-onset systemic lupus erythematosus (JSLE) is a complex and heterogeneous immune-mediated disease. Cellular components have crucial roles in disease phenotypes and outcomes. We aimed to determine the associations of lymphocyte subsets with clinical manifestations and long-term outcomes in JSLE patients.

METHODS

A cohort of 60 JSLE patients provided blood samples during active disease, of whom 34 provided further samples during inactive disease. In a longitudinal study, blood samples were obtained from 49 of the JSLE patients at 0, 3, and 6 months. The healthy control (HC) group consisted of 42 age-matched children. Lymphocyte subsets were analyzed by flow cytometry.

RESULTS

The percentages of CD4+ T, γδ T, and NK cells were significantly decreased in JSLE patients compared with HC, while the percentages of CD8+ T, NKT, and CD19+ B cells were significantly increased. The percentage of regulatory T cells (Tregs) was significantly lower in JSLE patients with lupus nephritis (LN) than in non-LN JSLE patients and HC. The patients were stratified into high and low groups by the median frequency of each lymphocyte subset. The γδ T cells high group and NK cells high group were significantly related to mucosal ulcer. The CD4+ T cells high group was significantly associated with arthritis, and the NKT cells high group was substantially linked with autoimmune hemolytic anemia. The CD8+ T cells low group was mainly related to vasculitis, and the Tregs low group was significantly associated with LN. The percentage of Tregs was significantly increased at 6 months of follow-up, and the LN JSLE group had a lower Treg percentage than the non-LN JSLE group. Predictors of remission on therapy were high Tregs, high absolute lymphocyte count, direct Coombs test positivity, and LN absence at enrollment.

CONCLUSION

JSLE patients exhibited altered lymphocyte subsets, which were strongly associated with clinical phenotypes and long-term outcomes.

Current Insights in Cutaneous Lupus Erythematosus Immunopathogenesis

Cutaneous Lupus Erythematosus (CLE) is a clinically diverse group of autoimmune skin diseases with shared histological features of interface dermatitis and autoantibodies deposited at the dermal-epidermal junction. Various genetic and environmental triggers of CLE promote infiltration of T cells, B cells, neutrophils, antigen presenting cells, and NK cells into lesional skin. In this mini-review, we will discuss the clinical features of CLE, insights into CLE immunopathogenesis, and novel treatment approaches.

NFI transcription factors provide chromatin access to maintain stem cell identity while preventing unintended lineage fate choices

Tissue homeostasis and regeneration rely on resident stem cells (SCs), whose behaviour is regulated through niche-dependent crosstalk. The mechanisms underlying SC identity are still unfolding. Here, using spatiotemporal gene ablation in murine hair follicles, we uncover a critical role for the transcription factors (TFs) nuclear factor IB (NFIB) and IX (NFIX) in maintaining SC identity. Without NFI TFs, SCs lose their hair-regenerating capability, and produce skin bearing striking resemblance to irreversible human alopecia, which also displays reduced NFIs. Through single-cell transcriptomics, ATAC-Seq and ChIP-Seq profiling, we expose a key role for NFIB and NFIX in governing super-enhancer maintenance of the key hair follicle SC-specific TF genes. When NFIB and NFIX are genetically removed, the stemness epigenetic landscape is lost. Super-enhancers driving SC identity are decommissioned, while unwanted lineages are de-repressed ectopically. Together, our findings expose NFIB and NFIX as crucial rheostats of tissue homeostasis, functioning to safeguard the SC epigenome from a breach in lineage confinement that otherwise triggers irreversible tissue degeneration.

An Update on the Pathogenesis of Skin Damage in Lupus

PURPOSE OF REVIEW

Lupus erythematosus (LE) is characterized by broad and varied clinical forms ranging from a localized skin lesion to a life-threatening form with severe systemic manifestations. The overlapping between cutaneous LE (CLE) and systemic LE (SLE) brings difficulties to physicians for early accurate diagnosis and sometimes may lead to delayed treatment for patients. We comprehensively review recent progress about the similarities and differences of the main three subsets of LE in pathogenesis and immunological mechanisms, with a particular focus on the skin damage.

RECENT FINDINGS

Recent studies on the mechanisms contributing to the skin damage in lupus have shown a close association of abnormal circulating inflammatory cells and abundant production of IgG autoantibodies with the skin damage of SLE, whereas few evidences if serum autoantibodies and circulating inflammatory cells are involved in the pathogenesis of CLE, especially for the discoid LE (DLE). Till now, the pathogenesis and molecular/cellular mechanism for the progress from CLE to SLE are far from clear. But more and more factors correlated with the differences among the subsets of LE and progression from CLE to SLE have been found, such as the mutation of IRF5, IFN regulatory factors and abnormalities of plasmacytoid dendritic cells (PDCs), Th1 cells, and B cells, which could be the potential biomarkers for the interventions in the development of LE. A further understanding in pathogenesis and immunological mechanisms for skin damage in different subsets of LE makes us think more about the differences and cross-links in the pathogenic mechanism of CLE and SLE, which will shed a light in predictive biomarkers and therapies in LE.

Infection and Lupus: Which Causes Which?

Infection is a leading cause of morbidity and mortality among patients with systemic lupus erythematous (SLE). Dysfunction of the innate and adaptive immune systems increases the risk of infection in patients with SLE. Infectious agents have also been theorized to play a role in the pathogenesis of SLE. This article summarizes our current knowledge of the infectious risk SLE patients face as a result of their underlying disease including abnormal phagocytes and T cells as well as the increased risk of infection associated with immunosuppressive agents used to treat disease. Pathogens thought to play a role in the pathogenesis of disease including EBV, CMV, human endogenous retroviruses (HERVs), and tuberculosis will also be reviewed, as well as the pathologic potential of microbial amyloids and the microbiome.

Association of γδ T Cell Compartment Size to Disease Activity and Response to Therapy in SLE

OBJECTIVE

Although γδT cells are widely recognized as pivotal elements in immune-mediated diseases, their role in the pathogenesis of SLE and therapeutic outcome remains under explored. The current study aims to characterize the γδT cell compartment in SLE and correlate its status to disease severity and response to therapy.

METHODS

Human peripheral blood-derived γδ T cells were isolated from 14 healthy volunteers and 22 SLE patients (before and after 4 and 12 weeks following the onset of glucocorticoids (GC), mycophenolatemofetil (MMF) orhydroxychloroquine (HCQ) treatment). The γδ T cells were characterized using flow cytometry. In addition, serum concentration of IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10 and IL-17A was determined by cytometric bead array (CBA).

RESULTS

The SLEDAI scores dropped significantly following therapy in a subset of patients (responders-R) but not in some (non- responders-NR). Peripheral blood γδ T cells in general, and γ9+δ T cells and TNF-α/IL-17-secreting CD4-CD8-γδ T cell subsets in particular, were decreased in SLE compared to healthy controls. The numbers of the γδ T cell subsets reached levels similar to those of healthy controls following therapy in R but not in NR. Serum IL-6, IL-10 and IL-17 but not IFN-γ and TNF-α were significantly increased in SLE compared to the healthy controls and exhibited differential changes following therapy. In addition, inverse correlation was observed between SLEDAI scores and γδ T cell compartments, especially with TNF-α+γδT cells, TNF-α+γ9+δT cells and IL17+CD4-CD8-γδT cells subsets. Differential correlation patterns were also observed between serum cytokine levels and various γδ T cell compartments.

CONCLUSIONS

A strong association exists between γδ T cell compartments and SLE pathogenesis, disease severity and response to therapy.

The Role of γδ T Cells in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that is characterized by the overproduction of autoantibodies against an array of nuclear and cytoplasmic antigens and affects multiple organs, such as the skin, joints, kidneys, and neuronal tissues. T cells have been recognized as important players in the development of SLE due to their functions in cytokine secretion, antigen presentation, and supporting B cells for antibody production. γδ T cells are a minor population of T cells that play important roles in infection and tumor-associated disease. In recent years, the role of γδ T cells in autoimmune diseases has been investigated. In this review, we discussed the role of γδ T cells in the pathogenesis of SLE.

Elevated apoptosis and impaired proliferation contribute to downregulated peripheral γ δ T cells in patients with systemic lupus erythematosus

OBJECTIVE

To investigate the frequency of peripheral γ δ T cells in patients with systemic lupus erythematosus (SLE) and its correlation with disease activity and to analyze the apoptotic status, proliferation ability, and intracellular cytokine profile of these cells.

METHODS

Flow cytometry was performed to detect the percentage and intracellular cytokine expression of peripheral γ δ T cells from SLE patients. Annexin-V/PI double staining was applied to determine the proportion of apoptotic γ δ and CD3(+) T cells. γ δ T cell proliferation was analyzed by CFSE labeling technique.

RESULTS

The percentage and absolute number of γ δ T cells were remarkably decreased in active SLE patients compared to those in inactive patients and healthy controls, with γ δ T cell count negatively correlated with disease activity. Compared with healthy controls, peripheral γ δ T cells from active SLE patients exhibited higher apoptotic rate and lower proliferation ability, as well as elevated expression of intracellular IFN-γ , IL-4, IL-10, and TGF- β , but not IL-17 or Foxp3.

CONCLUSION

Decreased γ δ T cells in the peripheral blood of SLE patients might be caused by upregulated apoptosis and downregulated cell proliferation. These γ δ T cells may secret both pro- and anti-inflammatory cytokines to perform their functions in SLE.

Primary cicatricial alopecia: recent advances in understanding and management

Primary cicatricial alopecias (PCA) are a rare group of disorders, in which the hair follicle is the main target of destructive inflammation resulting in irreversible hair loss with scarring of affected lesions. The most typical clinical manifestation of PCA is the loss of visible follicular ostia. The histopathological hallmark of a fully developed lesion is the replacement of the hair follicle structure by fibrous tissue. PCA could share similar clinical manifestations and eventually lead to "burn-out" alopecia. Some subsets are hardly distinguishable histopathologically and the mechanisms that elicit such a destructive reaction have not been fully elucidated. Thus, the management of PCA represents one of the most challenging clinical problems for dermatologists. The aim of this review is to provide a concise and comprehensive summary of recent advances in PCA management, especially focusing on novel methodologies to aid diagnosis, and updates on our understanding of the etiopathogenesis. Dermoscopy, a new pathological preparation technique and direct immunofluorescence analysis enable more accurate clinicopathological diagnosis of PCA. Microarray analysis may be beneficial to distinguish PCA subtypes. Currently suggested mechanisms underlying PCA include loss of immune protection of stem cells, impaired stem cell self-maintenance, enhanced autoimmunity by pro-inflammatory cytokines and environmental/genetic predispositions. Interestingly, recent data indicates the association between lipid metabolism dysregulation and PCA development, implying an important role of the sebaceous gland dysfunction in the etiopathogenesis. Based on that hypothesis and observations, novel therapeutic approaches have been proposed, including the use of peroxisome proliferator-activated receptor-γ agonist for lichen planopilaris.

The pathogenesis of primary cicatricial alopecias

Cicatricial (scarring) alopecia results from irreversible damage to epithelial stem cells located in the bulge region of the hair follicle, generally as a result of inflammatory mechanisms (eg, in the context of autoimmune disease). In primary cicactricial alopecia (PCA), the hair follicle itself is the key target of autoaggressive immunity. This group of permanent hair loss disorders can be classified into distinct subgroups, characterized by the predominant peri-follicular inflammatory cell type. In none of these PCA forms do we know exactly why hair follicles begin to attract such an infiltrate. Thus, it is not surprising that halting or even reversing this inflammation in PCA is often extremely difficult. However, increasing evidence suggests that healthy hair follicle epithelial stem cells enjoy relative protection from inflammatory assault by being located in an immunologically "privileged" niche. Because this protection may collapse in PCA, one key challenge in PCA research is to identify the specific signaling pathways that endanger, or restore, the relative immunoprotection of these stem cells. After a summary of pathobiological principles that underlie the development and clinical phenotype of PCA, we close by defining key open questions that need to be answered if more effective treatment modalities for this therapeutically very frustrating, but biologically fascinating, group of diseases are to be developed.

Animal models of spontaneous and drug-induced cutaneous lupus erythematosus

Skin lesions are one of the most common manifestations of lupus erythematosus (LE) disorders such as systemic LE and discoid LE. The etiology of cutaneous LE is not fully understood. To address this issue, appropriate animal models frequently clarify the etiology and pathogenesis of autoimmune diseases, although no single animal model perfectly mimics a human disease. A common dermatological finding in many SLE-prone mouse strains is the deposition of immunoglobulins at the dermoepidermal junction. Over the past decade, the most exciting and important finding has been the discovery of the Fas-defect in the pathogenesis of the autoimmune MRL/lpr mouse, which is a good model for the spontaneous development of skin lesions similar to those seen in human LE. The analysis of MRL/lpr mice showed a close association between immunoglobulin deposits and the appearance of skin lesions. Transgenic and knock out mice have advanced the investigation of cutaneous LE. Furthermore, the model of drug-induced cutaneous LE can yield additional insight since the trigger is clear in drug-induced LE. Cutaneous LE lesions can also be induced in TCRalpha-/- mice treated with fluorouracil and ultraviolet B light irradiation. Studies on both spontaneous and experimental models will elucidate the pathogenesis of complicated and multifactorial cutaneous LE.

Susceptibility of T cell receptor-alpha chain knock-out mice to ultraviolet B light and fluorouracil: a novel model for drug-induced cutaneous lupus erythematosus

The anticancer agent 5-fluorouracil (FU) frequently induces cutaneous lupus erythematosus (LE) lesions on sun exposed sites. Based on this observation, we have tried to establish a cutaneous LE model of C57BL/6 J (B6) mice, B6 T cell receptor (TCR)-alpha(-/-) mice and B6 TCR-delta(-/-) mice treated with FU and/or ultraviolet B light (UVBL) in order to clarify the role of T cells and the cytokine profile of cutaneous lupus lesions. Cutaneous LE-like skin lesions could be induced in TCR-alpha(-/-) mice with low FU (0.2 mg) plus UVBL, and in B6 mice treated with a high dose of FU (2.0 mg) plus UVBL. In contrast, low FU plus UVBL induced such skin lesions in TCR-delta(-/-) mice at a very low incidence. Specifically, the skin lesions of TCR-alpha(-/-) mice with low FU plus UVBL appeared more rapidly and were more severe than lesions in B6 mice. The former had the common characteristic features of human chronic cutaneous LE such as typical histology, positive IgG at the dermoepidermal junction, low antinuclear antibody and low mortality. Furthermore, a Th1 response was induced in the development of drug-induced cutaneous LE. FU and UVBL-induced cutaneous LE-like eruption is an excellent model for better understanding the pathomechanisms of skin lesion development in LE.

Distinct tumour specificity and IL-7 requirements of CD56(-)and CD56(+) subsets of human gamma delta T cells

gamma delta T cells are believed to recognize tissue injury caused by infections, tumours, as well as chemical and physical agents. The present study was carried out to study the feasibility of the ex vivo expansion of gamma delta T cells from healthy individuals, and to determine their functional capacity against tumours. We selectively expanded the peripheral gamma delta T cells of five donors against a myeloma cell line, XG-7. Under optimal conditions, the resulting bulk cultures comprised about 82% of the gamma delta T cells, more than 90% of which showed the T-cell receptor (TCR)-V gamma 9 delta 2 rearrangement. These gamma delta T-cell cultures exhibited TCR-gamma delta dependent cytotoxicity against different tumour cell lines including Molt-4, BJAB, Epstein-Barr virus (EBV) transformed lymphoid cell lines (LCL), and the nasopharyngeal carcinoma (NPC) cell lines, CNE2 and 915, in addition to the stimulator XG-7. By competitive cytotoxicity assays, the gamma delta T cells demonstrated recognition of at least three distinct target specificities expressed by Molt-4, CNE2 and LCL, respectively, which were related to that expressed by the stimulator XG-7 cells. The recognition of the specificity expressed by XG-7 and Molt-4 was further shown to require the participation of heat shock protein (HSP). The specificity expressed by CNE2 and 915 was preferentially recognized by the CD56 subset of gamma delta T cells, which could be sustained in the presence of interleukin (IL)-7. These results suggested that gamma delta T-cell immunity against tumour cell lines may be acquired in response to other types of tissue injury and, hence, implicates a role for their use in the prevention and treatment of tumours.

Circulating Vdelta1+ T cells are activated and accumulate in the skin of systemic sclerosis patients

OBJECTIVE

An increased percentage of Vdelta1+/gamma/delta T cells has been detected both in the peripheral blood and bronchoalveolar lavage fluid of patients with systemic sclerosis (SSc). This study evaluated the subset distribution, activation status, and expression of cellular adhesion molecules, such as intercellular adhesion molecule 1 (CD54), very late activation antigen alpha4 (CD49d), and lymphocyte function-associated antigen 1alpha (CD11a), on circulating gamma/delta T cells, as well as their presence in the skin of SSc patients.

METHODS

We studied 12 patients with SSc and 16 healthy volunteer donors. The distribution, activation status, and expression of cellular adhesion molecules were studied by flow cytometry; their presence in SSc patient skin was evaluated by immunohistochemistry.

RESULTS

We found that the percentages and absolute numbers of peripheral blood gamma/delta T cells, CD16, CD8, CD45RO, CD25, HLA-DR, CD54, and CD11a coexpression did not differ significantly from those of the controls. CD49d gamma/delta T cells were significantly increased in SSc patients (2.3%) compared with controls (0.5%). A marked increase in the ratio of Vdelta1+ cells to gamma/delta cells was observed in the patients (72%) compared with the controls (31%). The Vdelta1+ subset showed a significant expression of both HLA-DR (83% of total Vdelta1+ cells) and CD49d (90% of total Vdelta1+ cells) compared with the controls (20.5% and 60%, respectively). In the skin, the absolute numbers of gamma/delta T cells were found in striking amounts in perivascular areas, particularly in the early edematous phase of SSc (22.58 in patients and 0 in controls); the majority of gamma/delta T cells were Vdelta1+ (19 in patients and 0 in controls). In the advanced phase of SSc, Vdelta1+ T cells were also increased compared with controls (3.5 versus 0).

CONCLUSION

Our results show that Vdelta1+ T cells express both adhesion molecules and activation markers, and strongly support gamma/delta T cell homing to sites of inflammation. The increase in the Vdelta1 subset suggests a selective V gene subset expansion.

Gamma delta T-cells in human cutaneous immunology

Gamma delta T-Cells represent a minor subpopulation of T-lymphocytes in man and their role in normal and diseased human skin is unknown. This article is a comprehensive review of T-lymphocytes bearing the gamma delta T-cell receptor in normal and pathological human skin. Firstly, we have documented the occurrence of gamma delta T-cells in normal skin and in a range of reactive and malignant skin conditions. We have then discussed the experimental findings regarding the repertoire used by gamma delta T-cells in normal human skin and in cutaneous disorders with an increased percentage of gamma delta T-cells.

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.

Immunobiology of mouse dendritic epidermal T cells: a decade later, some answers, but still more questions

Over the past decade, overwhelming evidence has accumulated in many species, most notably in mice, that epithelial sites such as skin, intestine, and reproductive tract are populated with relatively discrete subsets of gamma delta cells. Such studies have identified several distinguishing and, in some cases, unique features of the dendritic epidermal T cells (DETC) populating the skin of all normal mice: homogeneous V5-J1-C gamma 1/V1-D2-J2-C delta T-cell receptors devoid of junctional diversity, apparent tissue restriction in adult mice to the skin, an important role for active hair growth in their localization and/or proliferation in the skin, and a capacity to recognize an antigen expressed on stressed epidermal cells. These properties have led to the hypothesis that DETC play distinctive roles in cutaneous immune surveillance and/or immunoregulation via recognition of a common self-antigen expressed by adjacent cells under various potentially harmful circumstances. Despite substantive advances in our knowledge about gamma delta cells in general (e.g., recent evidence that their manner of antigen recognition may be fundamentally different from that used by conventional alpha beta T cells) and about epithelial-specific subsets such as murine DETC in particular, it is clear that, compared with our understanding of alpha beta cells, major gaps still exist in our understanding of these cells. Persisting questions about DETC include: precise identification of the ligands for their homogenous T-cell receptors, the cellular and molecular requirements for their activation, their full range of functional activities, the reason(s) for the absence in normal human skin of a precise morphologic and phenotypic homologue, and, perhaps most important, their biologically relevant role(s) in cutaneous physiology, immunity, and/or pathology.

Gamma/delta T cells and human skin reactivity to heavy metals

Gamma/delta T cells may act as a first line of defence and respond to stress signals from the surrounding tissue. In the present investigation the occurrence of gamma/delta T cells was studied in the human skin after application of heavy metal salts by a routine epicutaneous patch-testing procedure. Gamma/delta cells were not found in normal skin. They were observed in all 14 allergic or irritant patch-test reactions to gold chloride and in 6/8 such reactions to mercuric chloride, where they comprised 16 +/- 6% and 15 +/- 6%, respectively, of the CD3+ cells in the dermis. They were also epidermotropic. Very few of these cells were found in reactions to salts of nickel and silver, except that they were increased in hair follicle epithelium in a reaction to silver nitrate. The gamma/delta cells expressed the V delta 2 and the V gamma 2 gene segments and were CD4-8-, indicating that they had the same phenotype as gamma/delta lymphocytes in the peripheral blood. Moreover, they were 'memory' T cells. These results indicate that gamma/delta lymphocytes play a role in the skin defence against highly reactive heavy metals.

Association between chronic cutaneous lupus erythematosus and HLA class II alleles

CCLE, a disease entity at the benign end of the lupus spectrum, is characterized by marked photosensitivity and skin lesions in sun-exposed areas. The histopathology of lesions resembles hypersensitivity type IV reactions. We have asked whether an association between class II alleles and CCLE exists. RFLP analysis of HLA-DQA genes revealed a Taq I HLA-DQA1 allelic restriction fragment overrepresented in a group consisting of 26 patients as compared to healthy control individuals. This result was corroborated by typing with oligonucleotide probes. The presence of the DQA1*0102 allele in the patients' group led to a relative risk of 4.57, with a statistical significance of p < 0.05 after correction for 36 comparisons. Although not statistically significant, it is interesting that all patients possess in at least one of their HLA-DQA1 alleles a nucleotide sequence coding for the amino acid glutamine at position 34 of the DQ alpha molecule. The expected frequency of these alleles in the control population amounts to 82%. The HLA-DRB1*16 allele, which is found in linkage disequilibrium with the HLA-DQA1*0102 allele, is also observed at an increased frequency in the patient's group, though the association was not significant after correction for the number of comparisons. However, no associations of CCLE with alleles at the HLA-DPB1 locus was found. The association of CCLE with certain HLA class II alleles points to an involvement of HLA-DQ and/or -DR molecules in the pathogenesis of the disease. Alternatively, genetic loci in linkage disequilibrium may code for elements which contribute to the development of CCLE.(ABSTRACT TRUNCATED AT 250 WORDS)

The skin immune system: lupus erythematosus as a paradigm

Lupus erythematosus (LE) was first described as a clinical dermatological entity in 1851. The possibility of serious systemic manifestations became recognized by 1872 as the result of the work of M. Kaposi. Since then, it took a long time before LE was recognized to be an immunological disease. Recognition of antinuclear antibodies and their deposition at the basal membrane region in skin resulted in two concepts of LE pathogenesis. In one, antibody complexing and complement activation with generation of the membrane attack complex (C5-C9) is thought to be the origin of the chronic inflammatory reaction. In the other, antibody deposition enables antibody dependent cellular cytotoxicity, leading to hydropic degeneration of the basal epidermal layer and subsequent chronic inflammation. Norris postulated in 1993, that the epidermis acts as a pro-inflammatory organ, in which an UVB-induced increase in cytokine production is followed by increased expression of adhesion molecules on keratinocytes as well as dermal endothelial cells. Translocation of certain antigens (i.e. Ro & La) to which circulating auto-antibodies exist in LE, enables recognition by adhesion molecule directed skin-invading T cells with subsequent cytotoxic effector activity. A persistent chronic inflammatory reaction then ensues. A similar development in knowledge may be seen in the history of immunodermatology. Originally, lupus erythematosus could not be recognized as an immune disease, since concepts of immunology were virtually non-existent when LE was first described. Immunology, In the first half of this century, was mainly antibody-oriented and thus came the concept of (S)LE as an antibody-mediated disease.(ABSTRACT TRUNCATED AT 250 WORDS)

T cell receptor expression by dendritic epidermal T cells

Dendritic epidermal T cells (DETC) in murine epidermis express the gamma delta T cell receptor (TCR). The major population of DETC utilize V gamma 5 and V delta 1 without any junctional diversity, corresponding to the earliest fetal thymocytes which express TCR gamma delta. Using PCR, we recently found another population of DETC which express V gamma 1-V delta 6 with junctional diversity in addition to V gamma 5-V delta 1, although they exist in small numbers in normal mice. In athymic nude mice, V gamma 1+ cells also exist. Therefore, this subset of gamma delta T cells is the product of an extrathymic pathway. These V gamma 1+ cells may recognize mycobacterium antigen or heat shock protein (HSP), thus playing an important role in the first defense of the skin. In contrast to normal mice, in nude mice, we could not detect any DETC using anti CD3 epsilon antibody (2C11). In order to solve this puzzle, we examined the components of TCR complex utilizing immunoprecipitation and northern blot analysis. TCR is composed of either alpha beta or gamma delta chains associated with CD3 gamma, delta, epsilon and zeta-zeta chains. By immunoprecipitation of 125I labelled DETC cell lines using anti-CD3 epsilon antibody, we detected gamma delta chains and CD3 gamma and CD3 epsilon chains, but not CD3 delta or CD3 zeta chains. Northern blot analysis showed that these cells express CD3 gamma, epsilon, and zeta chains, but not the CD3 delta chain.(ABSTRACT TRUNCATED AT 250 WORDS)