STAT3 signaling in CD4+ T cells is critical for the pathogenesis of chronic sclerodermatous graft-versus-host disease in a murine model.

Donor CD4+ T cells are thought to be essential for inducing delayed host tissue injury in chronic graft-versus-host disease (GVHD). However, the relative contributions of distinct effector CD4+ T cell subpopulations and the molecular pathways influencing their generation are not known. We investigated the role of the STAT3 pathway in a murine model of chronic sclerodermatous GVHD. This pathway integrates multiple signaling events during the differentiation of naive CD4+ T cells and impacts their homeostasis. We report that chimeras receiving an allograft containing STAT3-ablated donor CD4+ T cells do not develop classic clinical and pathological manifestations of alloimmune tissue injury. Analysis of chimeras showed that abrogation of STAT3 signaling reduced the in vivo expansion of donor-derived CD4+ T cells and their accumulation in GVHD target tissues without abolishing antihost alloreactivity. STAT3 ablation did not significantly affect Th1 differentiation while enhancing CD4+CD25+Foxp3+ T cell reconstitution through thymus-dependent and -independent pathways. Transient depletion of CD25+ T cells in chimeras receiving STAT3-deficient T cells resulted in delayed development of alloimmune gut and liver injury. This delayed de novo GVHD was associated with the emergence of donor hematopoietic stem cell-derived Th1 and Th17 cells. These results suggest that STAT3 signaling in graft CD4+ T cells links the alloimmune tissue injury of donor graft T cells and the emergence of donor hematopoietic stem cell-derived pathogenic effector cells and that both populations contribute, albeit in different ways, to the genesis of chronic GVHD after allogenic bone marrow transplantation in a murine model.

Clinicohistopathological correlations in juvenile localized scleroderma: studies on a subset of children with hypopigmented juvenile localized scleroderma due to loss of epidermal melanocytes.

BACKGROUND: Localized scleroderma or morphea is a connective tissue disorder characterized by fibrosis of the skin and subcutaneous tissue. Excessive accumulation of collagen underlies the fibrosis, yet the pathogenesis is unknown. A subset of localized scleroderma/morphea, juvenile localized scleroderma (JLS), affects children and adolescents. OBJECTIVES: The clinical and microscopic features of JLS have not been fully characterized. The goal is to better characterize the microscopic features of JLS. METHODS: We collected a distinctive data set of 35 children with JLS, 19 (54%) of whom presented with hypopigmented lesions, and performed a retrospective chart and pathology review. We had adequate tissue for immunostaining studies on 8 of these individuals. RESULTS: We found that: (1) CD34 and factor XIIIa immunostaining, reported previously in adult morphea and scleroderma, when used with clinical information, is valuable for confirming a diagnosis of JLS; and (2) presence of hypopigmented lesions in JLS correlates with immunostaining studies. Decreased numbers of MelanA(+) melanocytes were present at the dermoepidermal junction in lesional skin in two of 3 children with hypopigmented JLS and in two of 4 children with nonhypopigmented JLS. LIMITATIONS: The number of cases is small, a function of the small number of children who have biopsy specimens with material sufficient for multiple immunostaining procedures. CONCLUSIONS: These results provide a useful immunostaining method for confirmation of the diagnosis of JLS. They suggest a complex autoimmune phenotype in some children with JLS.

Keratinocyte but not endothelial cell-specific overexpression of Tie2 leads to the development of psoriasis.

Psoriasis is initiated and maintained through a multifaceted interplay between keratinocytes, blood vessels, gene expression, and the immune system. One previous psoriasis model demonstrated that overexpression of the angiopoietin receptor Tie2 in endothelial cells and keratinocytes led to the development of a psoriasiform phenotype; however, the etiological significance of overexpression in each cell type alone was unclear. We have now engineered two new mouse models whereby Tie2 expression is confined to either endothelial cells or keratinocytes. Both lines of mice have significant increases in dermal vasculature but only the KC-Tie2-overexpressing mice developed a cutaneous psoriasiform phenotype. These mice spontaneously developed characteristic hallmarks of human psoriasis, including extensive acanthosis, increases in dermal CD4(+) T cells, infiltrating epidermal CD8(+) T cells, dermal dendritic cells and macrophages, and increased expression of cytokines and chemokines associated with psoriasis, including interferon-gamma, tumor necrosis factor-alpha, and interleukins 1alpha, 6, 12, 22, 23, and 17. Host-defense molecules, cathelicidin, beta-defensin, and S100A8/A9, were also up-regulated in the hyperproliferative skin. All of the phenotypic traits were completely reversed without any scarring following repression of the transgene and were significantly improved following treatment with the anti-psoriasis systemic therapeutic, cyclosporin A. Therefore, confining Tie2 overexpression solely to keratinocytes results in a mouse model that meets the clinical, histological, immunophenotypic, biochemical, and pharmacological criteria required for an animal model of human psoriasis.

Disseminated superficial actinic porokeratosis co-existing with linear and verrucous porokeratosis in an elderly woman: Update on the genetics and clinical expression of porokeratosis.

Disseminated superficial actinic porokeratosis (DSAP) is the most common form of porokeratosis, occurring mainly in women on the extremities as atrophic patches rimmed by a ridge of keratin (the cornoid lamella that is diagnostic of porokeratosis histologically and is thought to be a clonal keratinocyte proliferation). DSAP can sometimes coexist with other forms of porokeratosis (Mibelli, linear porokeratosis, porokeratosis palmaris et plantaris disseminata, and punctate porokeratosis). Rare variants of linear porokeratosis are the hyperkeratotic and verrucous forms which usually occur on the buttocks or perianal area. We present clinical and histopathologic findings from biopsy specimens of a 73-year-old woman with DSAP on the distal extremities, linear/segmental porokeratosis on thighs, and verrucous porokeratosis on buttocks and mons pubis. The verrucous lesions had been present for 30+ years, the DSAP and linear lesions for 10+ years. Biopsy specimens from distal extremity showed classic features of DSAP with infrequent cornoid lamellae separated by atrophic epidermis. Biopsy specimens from the mons pubis and thigh showed epidermal hyperplasia with multiple, almost contiguous, broad cornoid lamellae. Coexisting variants of porokeratosis are rare and our conclusions are drawn from a few cases in the literature. The rare variants of porokeratosis are of interest because the clinical morphology correlates with the histopathology.

Scleroderma.

The prototypic autoimmune diseases involving skin (lupus, dermatomyositis) typically result in epithelial injury and autoantibodies to characteristic cellular antigens. Disease-specific autoantibodies are also found in scleroderma, but scleroderma is different from other cutaneous autoimmune diseases because epithelial injury does not occur. Multiple factors and combinations of factors (immune system, vascular and extracellular matrix abnormalities) are the most likely triggers in an individual with a genetic predisposition to scleroderma. These lead to increased synthesis of normal collagen in skin, lungs and gut in the systemic form of scleroderma, systemic sclerosis. The hypotheses for the pathophysiology of scleroderma are diverse and include abnormal immunologic processes such as cytokine and chemokine dysregulation, abnormal T cell signaling, B cell dysfunction, injury due to autoantibodies to endothelial cells, persistent wound healing condition due to dysregulation of matrix homeostasis, abnormalities in the fibrinolytic system, polymorphisms in critical molecules of the immune system and matrix homeostasis, and microchimerism due to fetal/maternal placental exchange of HLAcompatible cells. Systemic sclerosis/scleroderma is chronic and progressive. To date, no definitive therapy is effective for any of the scleroderma variants, although agents for the vascular dysfunction have some utility. Hematopoietic bone marrow or stem cell transplantation before significant tissue fibrosis has occurred may be the most effective treatment.

A case of recurrent pseudolymphomatous folliculitis: A mimic of cutaneous lymphoma.

Pseudolymphomatous folliculitis is a rare entity. We present a 62-year-old man with a recurrent solitary nodule on his nose requiring multiple excisions. Microscopic examination of the excisions showed a dense lymphocytic infiltrate containing numerous histiocytes and S100+, CD1a+ dendritic cells that surrounded and infiltrated hypertrophic hair follicles. Diffuse sheets of CD3+ T cells and nodular clusters of CD20+ B cells were also seen. There was normal reactive pattern of follicular centers. Light chain restriction was not detected. T-cell receptor and immunoglobulin heavy chain gene rearrangements by polymerase chain reaction revealed negative findings. A diagnosis of pseudolymphomatous folliculitis was made based on the hypertrophic hair follicles, periadnexal S100+ and CD1a+ dendritic cells, and negative clonal gene rearrangement study findings. This case of recurrent pseudolymphomatous folliculitis is instructive because of the resemblance to cutaneous lymphomas and cutaneous lymphoid hyperplasias, and the need for correct diagnosis to avoid overtreatment of this indolent condition.

Pagetoid reticulosis in a 5-year-old boy.

We present a rare case of pagetoid reticulosis arising in a 5-year-old white boy. He had a history of a large chronic erythematous, scaly patch on his left buttock that had shown intermittent partial response to a topical antifungal medication. A punch biopsy specimen revealed dramatic epidermal hyperplasia, with parakeratosis and prominent exocytosis of single and clustered mononuclear cells (Pautrier's microabscesses) into the epidermis. Some of these exhibited hyperchromatic nuclei with irregular contours. They stained prominently for CD3, CD4, and CD8, with a predominance of CD8(+) cells. T-cell receptor gene rearrangement by polymerase chain reaction was negative for a clonal process on a second biopsy specimen that was nondiagnostic on routine sections. Pagetoid reticulosis is an indolent, unilesional variant of mycosis fungoides, in which the atypical T cells may express a CD4(-)/CD8(+) phenotype. This is in contrast to primary cutaneous epidermotropic CD8(+) cytotoxic T-cell lymphoma, which is often very aggressive with a poor outcome. Pagetoid reticulosis is exceedingly rare in children and adolescents. Two features predict a benign course in this 5-year-old child: the unilesional clinical presentation and the CD8 predominance of the epidermal lymphocytes.

"I forgot to shave my hands": A case of spiny keratoderma.

A 57-year-old Caucasian man presented with multiple asymptomatic spiny papules on the palms and soles that he had been shaving off with a razor for many years. He was otherwise healthy with no personal or family history of skin disease or malignancy. A diagnosis of spiny keratoderma of the palms and soles or "music box spine dermatosis" was made. The clinical, histologic, and electron-microscopic features of spiny keratoderma are distinct. This entity previously had multiple classifications and it is important to distinguish it from other keratodermas as some keratodermas can be linked to cutaneous and internal malignancies and conditions: polycystic kidney disease, liver cysts, Darier's disease, and hyperlipoproteinemia among others. Spiny keratodermas can have systemic associations and do not resolve spontaneously. Treatment is generally ineffective.

A male infant with anhidrotic ectodermal dysplasia/immunodeficiency accompanied by incontinentia pigmenti and a mutation in the NEMO pathway.

Patients with anhidrotic ectodermal dysplasia and immunodeficiency (EDA-ID) have mutations in the gene on the X chromosome encoding nuclear factor kappaB (NF-kappaB) essential modulator (NEMO), resulting in conical teeth, sparse hair, anhidrosis or hypohydrosis, and recurrent bacterial infections. The same gene is mutated in incontinentia pigmenti (IP), and mutations that do not completely abolish NF-kappaB activity allow survival of male fetuses. We present a case of a 1-year-old boy with a history of EDA-ID who was evaluated for an eruption that intermittently affected his scalp, upper back, cheeks, legs, and arms. A biopsy specimen taken from the back showed the presence of compact dyskeratotic cells with fragmented nuclei and numerous apoptotic keratinocytes scattered throughout the spinous and granular layer. The diagnosis of EDA-ID with IP was made. This case illustrates the complexity and overlapping features of the genodermatoses involving signaling pathways of the cell.

Erythema nodosum in association with newly diagnosed hairy cell leukemia and group C streptococcus infection.

Erythema nodosum is an inflammatory reaction of the skin characterized by tender erythematous patches or nodules, usually located on the lower extremities. This report illustrates an association of erythema nodosum with a rare malignancy and an uncommon infectious agent in humans. There are many diseases associated with erythema nodosum; we propose that hairy cell leukemia and group C streptococcus be considered among this list.

Disruption of EphA2 receptor tyrosine kinase leads to increased susceptibility to carcinogenesis in mouse skin.

EphA2 receptor tyrosine kinase is frequently overexpressed in different human cancers, suggesting that it may promote tumor development and progression. However, evidence also exists that EphA2 may possess antitumorigenic properties, raising a critical question on the role of EphA2 kinase in tumorigenesis in vivo. We report here that deletion of EphA2 in mouse led to markedly enhanced susceptibility to 7,12-dimethylbenz(a)anthracene/12-O-tetradecanoylphorbol-13-acetate (DMBA/TPA) two-stage skin carcinogenesis. EphA2-null mice developed skin tumors with an increased frequency and shortened latency. Moreover, tumors in homozygous knockout mice grew faster and were twice as likely to show invasive malignant progression. Haploinsufficiency of EphA2 caused an intermediate phenotype in tumor development but had little effects on invasive progression. EphA2 and ephrin-A1 exhibited compartmentalized expression pattern in mouse skin that localized EphA2/ephrin-A1 interactions to the basal layer of epidermis, which was disrupted in tumors. Loss of EphA2 increased tumor cell proliferation, whereas apoptosis was not affected. In vitro, treatment of primary keratinocytes from wild-type mice with ephrin-A1 suppressed cell proliferation and inhibited extracellular signal-regulated kinase 1/2 (ERK1/2) activities. Both effects were abolished in EphA2-null keratinocytes, suggesting that loss of ERK inhibition by EphA2 may be one of the contributing mechanisms for increased tumor susceptibility. Interestingly, despite its tumor suppressive function, EphA2 was overexpressed in skin tumors compared with surrounding normal skin in wild-type mice, similar to the observations in human cancers. EphA2 overexpression may represent a compensatory feedback mechanism during tumorigenesis. Together, these results show that EphA2 is a novel tumor suppressor gene in mammalian skin.

Aggressive histiocytic disorders that can involve the skin.

Histiocytoses are a heterogeneous group of disorders that are characterized by the proliferation and accumulation of reactive or neoplastic histiocytes. Three classes of histiocytoses have been defined: class I, Langerhans cell disease; class II, non-Langerhans cell histiocytic disease without features of malignancy; and class III, malignant histiocytic disorders. Although the disorders in classes I and II usually have a benign appearance on histology and are commonly non-aggressive and self-healing, some can cause debilitating or even fatal outcomes. Such cases beg the question: what stimulates aggressive behavior of a classically benign disease? New molecular information may now provide insight into the driving force behind many of the aggressive histiocytoses. In this article, we review Langerhans cell disease and seven aggressive histiocytoses that can involve skin, discuss histologic features that may forecast a poor prognosis, and discuss the molecular findings that help to explain the pathophysiology of these aggressive histiocytic disorders.

Usefulness of flow cytometry in the diagnosis of mycosis fungoides.

BACKGROUND: The pathologic evaluation of mycosis fungoides (MF) is a challenging area in dermatopathology. OBJECTIVE: We sought to determine the usefulness of flow cytometry for the diagnosis of MF from skin biopsy specimens. METHODS: Skin biopsy specimens from 22 patients with a clinical suggestion for MF were evaluated by 4-color flow cytometry. The results were correlated with the International Society for Cutaneous Lymphoma (ISCL) MF diagnostic score and molecular studies for T-cell receptor gene rearrangement. RESULTS: A T-cell abnormality by flow cytometry was identified in all 11 patients with diagnostic ISCL scores whereas the 7 patients with either subdiagnostic ISCL scores or reactive histology showed no phenotypic abnormality by flow cytometry. In all, 10 of 11 patients with diagnostic skin biopsy specimens for MF had T-cell receptor gene rearrangements by polymerase chain reaction. Gene rearrangements were not detected in the subdiagnostic group. LIMITATIONS: Small study size was a limitation. CONCLUSION: Flow cytometry of skin biopsy specimens is a sensitive method for detecting abnormalities in MF and should be considered part of the routine workup of patients with a clinical suggestion of MF.

A case of Churg-Strauss syndrome associated with antiphospholipid antibodies.

Churg-Strauss syndrome (CSS) is a systemic vasculitis affecting both small- and medium-sized blood vessels, almost invariably affecting the lung, and frequently associated with cutaneous involvement. Microvascular vaso-occlusion leading to digital gangrene is not a feature of CSS. We report an unusual case of a patient with CSS with antiphospholipid antibodies who developed severe digital gangrene in addition to cutaneous vasculitis. The presence of antiphospholipid antibodies is not a feature usually seen in association with CSS. While the full clinical spectrum of CSS is still being defined, the identification of additional features associated with this syndrome might help to better understand the pathogenesis of the disease and to have an impact on both management and prognosis.

Immunohistochemical staining for CD45R isoforms in paraffin sections to diagnose mycosis fungoides-type cutaneous T-cell lymphoma.

The definitive diagnosis of mycosis fungoides (MF)-type cutaneous T-cell lymphoma (CTCL) is difficult because a cumulative set of information is typically required: clinical features, histopathology, and special diagnostic tests (typically immunophenotyping and T-cell receptor gamma [TCRgamma] gene rearrangement). Fresh tissue is not always available for the special tests. We report a simple and readily available procedure evaluating the staining pattern on formalin-fixed, paraffin-embedded skin that can help with the diagnosis of patch/plaque stage MF. We reviewed 92 cases of MF or probable MF that had clinical information, immunophenotyping and TCRgamma gene rearrangement studies and that had been evaluated in our multidisciplinary lymphoma conference. We used antibodies to the isoforms of CD45, CD45RO for mature T cells and CD45RB for subsets of T cells. When atypical CD45RB-positive/CD45RO-negative cells were seen in nonspongiotic epidermis, the individuals had a high cumulative clinical and histologic score for MF. In contrast, 15 cases of known contact dermatitis showed a reactive pattern of both CD45RB- and CD45RO-positive cells in spongiotic epidermis. We compared the epidermal CD45RB-positive/CD45RO-negative staining pattern with CD7 deficiency by immunophenotyping and TCRgamma gene rearrangement, two commonly used methods in the diagnosis of MF. The epidermal CD45RB-positive/CD45RO-negative staining pattern is comparable and may be better in equivocal cases of possible MF. Therefore immunostaining for CD45RB and CD45RO on paraffin sections is a simple, reliable, and convenient modality in the diagnosis of MF.

Microchimerism and skin disease: true-true unrelated?

Microchimerism, the stable presence of foreign cells in an individual, may result from trafficking during pregnancy or from organ or hematopoietic transplantation, and has been hypothesized to cause autoimmunity and certain skin diseases. Yet microchimeric cells are found in normal individuals and may be important to tissue repair. Thus microchimerism may be common, and finding microchimeric cells in diseased as well as normal tissue may be a "true-true unrelated" situation.

The distal and proximal regulatory regions of the involucrin gene promoter have distinct functions and are required for in vivo involucrin expression.

Involucrin is a marker of human keratinocyte differentiation. Previous studies show that the human involucrin gene promoter has two distinct regulatory regions - the proximal regulatory region (PRR) and the distal regulatory region (DRR). To study the role of these regions in vivo, we have constructed human involucrin promoter transgenic mice and monitored the impact of specific promoter mutations on involucrin gene expression. In this study, we monitor the impact of specific mutations on expression in a range of surface epithelia. We begin by confirming previous observations made in footpad epidermis by showing that the full-length involucrin promoter drives differentiation-appropriate expression in other surface epithelia, including epidermis, cervix, and esophagus. We further show that mutation of the activator protein AP1-5 site in the DRR completely eliminates transgene expression in all of these tissues. In contrast, mutation of the DRR Sp1 site reduces overall expression, but does not alter the differentiation dependence. Additional studies identify a DRR immediate suprabasal element (ISE). Deletion of the ISE results in a loss of transgene expression in the immediate suprabasal layers. Our studies also indicate that the PRR is important for appropriate transgene expression. Mutation of a PRR C/EBP (CCAAT enhancer binding protein) transcription factor binding site results in patchy/discontinuous expression. These studies suggest that AP1, Sp1, and C/EBP transcription factors are required for appropriate differentiation-dependent involucrin expression, and that the mechanism of regulation is similar in most surface epithelia.

Hair depigmentation during chemotherapy with a class III/V receptor tyrosine kinase inhibitor.

BACKGROUND: Hair pigmentation is regulated by several factors including the interaction of the ligand stem cell factor (SCF) with its class III receptor tyrosine kinase, c-kit. An interruption of SCF/c-kit signal transduction results in hair depigmentation. OBSERVATIONS: A 69-year-old white woman developed hair depigmentation and fine-textured hair while being treated with the phase I chemotherapeutic agent GW786034, a class III/V receptor tyrosine kinase inhibitor. Discontinuation of therapy resulted in a reversal of these hair changes. CONCLUSIONS: Treatment with oral GW786034 resulted in reversible hair depigmentation and change in hair growth rate and texture, which were most likely due to an incomplete inhibition of SCF/c-kit signaling, although the exact mechanism is unknown. It would be intriguing to investigate topical tyrosine kinase inhibitors as a treatment for unwanted body hair.

Latency-associated peptide prevents skin fibrosis in murine sclerodermatous graft-versus-host disease, a model for human scleroderma.

Murine sclerodermatous graft-versus-host disease (Scl GVHD), produced by transplanting B10.D2 bone marrow and spleen cells to lethally irradiated BALB/cJ mice, is a model for human scleroderma. Mice with Scl GVHD have skin thickening, lung fibrosis, cutaneous mononuclear cell infiltration, and upregulation of cutaneous transforming growth factor beta1 (TGF-beta1) and type I collagen mRNAs by day 21 after bone marrow transplantation. Elevated TGF-beta1 appears to be the critical cytokine driving fibrosis in Scl GVHD, which can be prevented with antibodies to TGF-beta administered early in disease. Here we demonstrate that we can also prevent skin thickening in mice with Scl GVHD with a naturally occurring antagonist to TGF-beta1, human latency-associated peptide (LAP). By quantitative real-time PCR analysis and immunostaining, LAP treatment also abrogates the upregulation of cutaneous TGF-beta1 and connective tissue growth factor mRNAs and type I collagen synthesis in Scl GVHD. In contrast to anti-TGF-beta antibodies, LAP at 4 ng total per mouse has no significant suppressive effect on cutaneous influx of T cells and monocytes or immune cell activation. LAP may be a potential new therapy in scleroderma and other TGF-beta-driven fibrosing disease that targets TGF-beta more specifically, without affecting systemic critical roles of TGF-beta on immune cell function.

Cutaneous lymphoid hyperplasia: a lymphoproliferative continuum with lymphomatous potential.

Cutaneous lymphoid hyperplasia (CLH) has been proposed to be the benign end of a continuum of lymphoproliferative disorders with cutaneous lymphoma at its malignant extreme. An intermediate condition, known as "clonal CLH," was first recognized by us and shown to be a transitional state capable of eventuating in overt lymphoma. To better determine the prevalence of dominant clonality and risk of lymphoma among CLH cases, we studied the immunohistology and clonality of fresh-frozen samples from 44 CLH patients referred to a multidisciplinary cutaneous lymphoproliferative disorders program. Using a large panel of lymphoid markers, the cases were divided into 38 typical mixed B-cell/T-cell type CLH and 6 T-cell-rich type (T-CLH), the latter containing > 90% T cells. Of the 44 patients, 38 had solitary or localized lesions (4 cases of T-CLH), and 6 had regional/generalized lesions (2 cases of T-CLH). Forty cases were of idiopathic etiology. Suspected etiologies among 4 other cases included mercuric tattoo pigment, doxepin, clozapine, and bacterial infection. Immunoglobulin heavy chain (IgH) and T-cell receptor (TCR)-gamma gene rearrangements (GR) were studied using polymerase chain reaction assays, which are approximately 80% sensitive. Overall, 27 cases (61%) showed clonal CLH: 12 IgH+ (27%; 3 cases of T-CLH); 13 TCR+ (30%; 1 case of T-CLH); and 2 IgH+/TCR+ (4%; neither case was T-CLH). Two cases (4%; 1 case of T-CLH) progressed to cutaneous B-cell lymphoma. Both of these patients presented with regional lesions. Our findings indicate that clonal overgrowth is common in CLH, links CLH to lymphoma, and probably involves both B- and T-cell lineages (although TCR GR by B cells and vice versa could not be ruled out). The high prevalence of dominant clonality in our series may have resulted from the sensitivity of our PCR assays as well as patient selection.