Dermatofibroma with diffuse eosinophilic infiltrate

Dermatofibroma, a common form of benign fibrous histiocytoma, is characterized by the presence of different cell types consisting of fibroblastic, histiocytic, and even multinucleated cells. Dermatofibromas are always accompanied by an inflammatory lymphoid cell reaction, including B cells and T cells at their border. To our knowledge, however, there is no report of an infiltration of eosinophils within this tumor. We describe a dermatofibroma on the pretibial region of an 8-year-old boy. Microscopic examination revealed a diffuse eosinophilic infiltration within the dermatofibroma, which was typically composed of histiocytic cells and mature collagen. The diagnosis of dermatofibroma was confirmed by demonstrating the immunoreactivity of tumor cells to an anti-factor XIIIa antibody.

Inflammatory and immune reactions associated with stratum corneum and neutrophils in sterile pustular dermatoses

In this review we present our own experimental findings as well as those from the literature related to the pathomechanisms for the inflammatory changes in psoriasis and its related diseases. A growing body of evidence has indicated that T cell-mediated immunity plays an important role in triggering and maintenance of psoriatic lesions. It has been revealed that lymphokines produced by activated T cells in psoriatic lesions have a strong influence on the proliferation of the epidermis. Characteristic neutrophil accumulation under the stratum corneum can be observed in the highly inflamed areas of psoriatic lesions. These neutrophils are chemotactically attracted and activated there by synergistic action of chemokines, IL-8 and Gro-alpha released by stimulated keratinocytes, and particularly by C5a/C5a des arg produced via the alternative complement pathway activation. We demonstrated that the infiltrating neutrophils adhere to iC3b-opsonized corneocytes to produce active oxygen and probably lysosomal enzymes. From a close relationship observed between neutrophil accumulation and high mitotic ratio of the lesional epidermis, we think that these stimulated neutrophils influence the growth and differentiation of epidermal keratinocytes. Aberrant expression of HLA-DR on neutrophils suggests their activation of infiltrating T cells in the presence of bacterial superantigen. These T cells in turn influence the transepidermal neutrophil migration through the effect of their cytokines on the keratinocyte production of proinflammatory mediators including IL-8 and C3. In this review we discuss the pivotal roles played by stratum corneum and neutrophils in several skin diseases, where neutrophils accumulate beneath the stratum corneum in a sterile condition.

Ultraviolet B radiation exerts enhancing effects on the production of a complement component, C3, by interferon-gamma-stimulated cultured human epidermal keratinocytes, in contrast to photochemotherapy and ultraviolet A radiation that show suppressive effects

The present study was designed to investigate by using enzyme-linked immunosorbent assay and reverse transcriptase-polymerase chain reaction methods whether photochemotherapy (PUVA) or ultraviolet (UV) B treatment affects C3 production by interferon (IFN)-gamma-stimulated keratinocytes cultured in serum-free medium. The results showed that PUVA and UVA reduced C3 production by IFN-gamma-stimulated epidermal keratinocytes dose-dependently, although the effect of PUVA was stronger than that of UVA alone. Interestingly, UVB induced an enhancement of C3 production at doses ranging from 10 to 50 mJ cm-2. This phenomenon was found at both the protein and mRNA levels. In every experiment, changes in C3 mRNA levels preceded those in its protein levels. Reduced C3 production at higher doses of 75 and 100 mJ cm-2 were probably due to cytotoxic effects of UVB. In our experimental system, PUVA, UVA or UVB treatment did not affect C3 production without IFN-gamma stimulation. Our results suggest that a reduction in C3 production by PUVA treatment may in part explain the efficacy of PUVA in the treatment of inflammatory dermatoses such as psoriasis, while the results of the UVB experiments may partially explain the proinflammatory nature of UVB.

Mediators of inflammation involved in UVB erythema

In this review, we discuss the mediators and inflammatory cells involved in UVB-induced inflammatory changes phase by phase. We especially stress the importance of IFNgamma secreted by activated CD4(+) T cells in the development of UVB erythema. We also speculate on the mechanism underlying regression of UVB erythema.

Role of neutrophils in induction of acute inflammation in T-cell-mediated immune dermatosis, psoriasis: a neutrophil-associated inflammation-boosting loop

A growing body of evidence has indicated that T-cell-mediated immunity plays an important role in triggering and maintenance of psoriatic lesions. In this review we present our own experimental results as well as those from the literature related to the pathomechanism of the development of inflammatory changes in psoriatic lesions. First of all it is important to acknowledge the fact that psoriatic lesions are not uniform as assumed by many authors but that they are actually rather heterogeneous both clinically and histologically even within the same plaques. Lymphokines produced by activated T cells in psoriatic lesions have a strong influence on the proliferation of the epidermis, whose stimulated kertinocytes released several cytokines, which in turn enhance the activation state of T cells. Thus, they form a vicious cycle, a T-cell-mediated inflammation-sustaining loop. Although the interaction between T-cell-mediated immunity and epidermal keratinocytes may well explain the maintenance of background "chronic" inflammatory changes diffusely observed throughout psoriatic lesions, it is not enough to explain the island-like, "acute" inflammatory changes observed within and at the border of the plaque lesions. Characteristic neutrophil accumulation under the stratum corneum can be observed in the highly inflamed and therapeutically recalcitrant areas of psoriatic lesions. They are chemotactically attracted and activated there by synergistic action of chemokines, IL-8 and Gro-a released by the stimulated keratinocytes, and particularly C5a/C5a des arg produced via the alternative complement pathway activation possibly on the surface of corneocytes. In this review, we emphasize that the accumulation of neurophils is not simply a passive event. We think that those stimulated neutrophils are able to influence not only the growth and differentiation of epidermal keratinocytes but also the activation-state of T cells by aberrant expression of HLA-DR on their surfaces as well as by their effects. These T cells in turn influence the transepidermal neutrophil migration through the effect of their lymphokines on the keratinocyte production of pro-inflammatory mediators including C3. Therefore, we propose a neutrophil-associated inflammation-boosting loop that may well explain the localized "acute" inflammatory changes scattered over the "chronic" psoriatic plaques as well as in the acutely inflamed lesions of pustular psoriasis.

[Cutaneous immune and inflammatory reactions to Malassezia furfur]

Initiation and aggravation of several inflammatory skin diseases are associated with Malassezia furfur. These are divided into at least two groups. In one group including tinea versicolor and Malassezia folliculitis, the growth of Malassezia furfur directly triggers the development of the cutaneous lesions. In another group including atopic dermatitis, seborrheic dermatitis, and psoriasis, cutaneous lesions already developed by other mechanisms are aggravated by the growth of Malassezia furfur. Recent progress of molecular biology techniques revealed that Malassezia furfur is divided into at least seven species. Since their clinical and histological findings are quite diverse, their differences cannot be explained solely by the difference in antigenicity of each Malassezia. Instead, the cutaneous defense mechanisms against Malassezia furfur must be considered. In this article, we reviewed the mechanisms at three levels: 1) barrier functions of the uppermost layer of the skin, the stratum corneum, 2) cytokine production by epidermal keratinocytes, and 3) immune and inflammatory responses by infiltrating neutrophils and T cells.

An increased ratio of interleukin-1 receptor antagonist to interleukin-1alpha in inflammatory skin diseases

IL-1 receptor antagonist (IL-1ra) is a cytokine that competitively binds the IL-1 receptor to antagonize IL-1 activity without any agonist function. Previous experiments indicated that the ratio of IL-1ra to IL-1alpha in the normal stratum corneum (SC) was much higher in the sun-exposed face than in the sun-protected area, upper arms. It was also reported by another laboratory that IL-1ra is increased in the lesional skin of psoriatic patients. This study was designed to measure the contents of IL-1alpha and IL-1ra in non-lesional and pathological SC obtained from inflammatory skin diseases including psoriasis and non-psoriatic dermatoses such as atopic dermatitis. The SC materials were obtained with a non-invasive tape-stripping method. Their soluble fractions were prepared and assayed for IL-1alpha and IL-1ra by enzyme-linked immunosorbent assays. As a result we confirmed the previous findings that the ratio of IL-1ra to IL-1alpha in the normal SC was much higher in the face than in the sun-protected sites, the trunk as well as extremities. Next, we found that IL-1alpha contents were significantly reduced in the SC samples obtained from inflammatory skin regardless of whether their IL-1ra contents increased or unchanged. Moreover, we noted that an increased ratio of IL-1ra to IL-1alpha in the SC was not specific to psoriasis, but was also found in other inflammatory skin diseases including atopic dermatitis. This ratio was found to become lower after successful treatment of these skin lesions with topical glucocorticoids. We conclude from these observations that the increased ratio of IL-1ra to IL-1alpha in the SC is a non-specific phenomenon that can occur in any inflammatory skin diseases regardless of the inflammatory pattern, probably reflecting a skin regulation process against various kinds of inflammation.

Release of monocyte chemoattractants by polymorphonuclear leukocytes stimulated by their adhesion to stratum corneum opsonized via complement activation, measured with a human acute monocytic leukemic cell line, THP-1

Stratum corneum (SC) exposed to living tissues, induces inflammation characterized by the formation of mixed cell granulomas consisting of infiltrative polymorphonuclear leukocytes (PMNs) and monocytes/macrophages. In this study, to clarify the mechanism for the later monocyte accumulation in SC-induced granulomas, we evaluated monocyte chemotactic activity induced by PMNs treated with serum-opsonized SC by using a human acute monocytic leukemic cell line, THP-1. When the supernatant was obtained from a PMN suspension cultured with opsonized plantar SC, higher THP-1 chemotactic activity was detected as compared with that cultured with non-opsonized SC. Although some concentrations of the chemokines, MIP-1alpha and MIP-1beta, were detected in supernatants obtained from the PMN suspensions cultured with plantar SC than in the control suspensions of PMN alone, their production by PMN was not influenced by the opsonization procedure. In contrast, MCP-1 was found to be secreted from PMN suspensions constitutively, showing no correlation to this THP-1 chemotactic activity. Moreover, HPLC analysis of PMN suspensions indicated that factors with far higher molecular weight values than these chemokines are involved in the chemotaxis of THP-1 cells.

Solitary subcutaneous mucinosis surrounded by bizarre-shaped, factor XIIIa-positive cells with intranuclear vacuoles

We describe a subcutaneous mucinosis developing in the right cheek of a 38-year-old man. Histologic examination revealed bipolar fibroblast-like cells embedded in a well demarcated mucinous stroma in the subcutis without a manifest reticulin network. In addition, bizarre, sometimes multinucleate, cells with intranuclear vacuoles were found at the periphery of the mucinous stroma. Immunohistologically, both the bipolar fibroblastic cells and bizarre-shaped cells were positive for vimentin, but were negative for smooth muscle A-actin, desmin, CD34, S100, trypsin, or chymotrypsin. However, the latter reacted to anti-factor XIIIa antibody, suggesting that they are derived from dermal dendritic cells. We think that this solitary subcutaneous mucinosis is a unique variant of cutaneous focal mucinosis, because neither a reticulin network nor reactivity to anti-smooth muscle A-actin antibody were demonstrable.

Annular elastolytic sarcoidosis of the face

We report a case of facial annular lesions in a non-diabetic, Japanese woman aged 78, the histopathological study of which showed noncaseating, epithelioid cell granuloma with multinucleated giant cells. Together with the aberrant laboratory data, these clinical and histopathological findings were considered to be compatible with those of sarcoidosis, but elastic tissue stain disclosed the existence of elastolytic changes which were clinically and histopathologically similar to those found in actinic granuloma or annular elastolytic giant cell granuloma. Based on a review of the literature, we believe that several annular elastolytic granulomatous diseases of the face form a disease spectrum, some of which are identified with intermediate features of these three diseases.

Dehydroepiandrosterone may be one of the regulators of cytokine production in atopic dermatitis

Previous studies in mice have shown that dehydroepiandrosterone (DHEA) increases the production of Th1-associated lymphokines, and of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), by lymphocytes. However, there are no reports concerning the effect of DHEA on the production of Th2-associated lymphokines, IL-4 and IL-5, by lymphocytes in humans. We examined serum DHEA levels in patients with atopic dermatitis (AD), which is thought to be associated with a higher activity of Th2 cells than of Th1 cells. We also studied the effects of DHEA on the production of IL-4 and IL-5 by human lymphocytes. Serum DHEA concentrations in 47 adult male patients with AD aged 19-30 years were significantly lower than those of 53 age-matched healthy male controls. Preincubation of peripheral blood mononuclear cells (PBMCs) with DHEA reduced the IL-4 production by concanavalin A-stimulated PBMCs. Their IL-5 production also showed a tendency to decrease. These results suggest that DHEA may be one of the regulators of IgE synthesis and eosinophil proliferation in patients with AD and it may act by controlling IL-4, IL-5 and IL-2 production by lymphocytes.

C3 production of cultured human epidermal keratinocytes is enhanced by IFNgamma and TNFalpha through different pathways

We investigated the regulation of C3 production by human cultured epidermal keratinocytes by enzyme-linked immunosorbent assay. The results showed that IFNgamma and TNFalpha enhanced the synthesis of C3 by epidermal keratinocytes in a concentration-dependent manner. Moreover, a protein kinase C (PKC) inhibitor blocked C3 production, whereas PMA enhanced it. There was a synergistic effect between IFNgamma and TNFalpha. In experiments to investigate the role of protein tyrosine kinase (PTK) in C3 production, we found that treatment with herbimycin A, a specific inhibitor for the c-Src-related PTK, caused significant enhancement of the C3 production induced by IFNgamma or TNFalpha, suggesting that c-Src-type PTK(s) provides a negative signal to C3 production. Each competitive inhibitor of PTK, genistein or tyrphostin, substantially increased the C3 production by IFNgamma at lower concentrations, although each agent had little effect on TNFalpha-associated production of C3 at the same concentrations. The data show that pro-inflammatory cytokines IFNgamma and TNFalpha synergistically augment C3 production by epidermal keratinocytes by different pathways.

Effects of acid phospholipids on ARF activities: potential roles in membrane traffic

ADP-ribosylation factors are a family of approximately 21 kDa GTP binding proteins which have been implicated as ubiquitous regulators of multiple steps in both exocytic and endocytic membrane traffic in mammals and yeast. Reversible membrane associations are thought to be an essential component in the physiological actions of ARF and are regulated by GTP binding. ARFs are unique among the superfamily of GTP binding proteins in having a strict dependence on phospholipids for nucleotide exchange. In addition, ARF proteins were found to bind phospatidylinositol 4,5-bisphosphate (PIP2) specifically. PIP2 was found to increase the rate of GDP dissociation and stabilize the nucleotide-free form of the protein. The previously described requirements for PIP2 in the ARF stimulated phospholipase D (PLD) activity and ARF GTPase activating protein (ARF GAP) assays provide the basis for a model in which PIP2 acts as a cofactor in one or more ARF pathways. There are potentially two distinct phospholipid binding sites each of which are coupled to the nucleotide binding site of ARFs.

Identification of a transforming growth factor beta-1 activator derived from a human gastric cancer cell line

It has been shown that some types of tumour cells produce activated transforming growth factor beta-1 (TGF-beta 1). However, the mechanism for the activation of TGF-beta 1 derived from tumour cells has not been fully elucidated. The present study was undertaken to characterise an activator of latent TGF-beta 1 secreted from a human gastric cancer cell line, KATO-III. Western blot analyses using antibodies for TGF-beta 1, latency associated peptide (LAP) and latent TGF-beta 1-binding protein (LTBP) revealed that, in the cell lysate of KATO-III, TGF-beta 1 protein was expressed as a small latent complex of TGF-beta 1 and LAP. This was also confirmed by a gel chromatographic analysis of the cell lysate obtained from KATO-III. A 2.5 kb transcript of TGF-beta 1 mRNA was detected in KATO-III cells by Northern blot analysis. A gel chromatographic analysis of the conditioned medium from KATO-III cells revealed, in addition to the active form of TGF-beta 1, a factor which activated latent TGF-beta 1 from NRK-49F cells at fractions near a molecular size of 65,000. This factor was inactivated by heat (100 degrees C), acidification, trypsin and serine protease inhibitors. TGF-beta 1 activity in KATO-III cell lysate was not detected in the untreated state, but potent TGF-beta 1 activity was detected after acid treatment. These results suggest that KATO-III releases not only a latent TGF-beta 1 complex but also a type of serine protease, different from plasmin, plasminogen activator, cathepsin D, endoglycosidase F or sialidase, which activates the latent TGF-beta 1 complex as effectively as acid treatment.

The myristoylated amino terminus of ADP-ribosylation factor 1 is a phospholipid- and GTP-sensitive switch

ADP-ribosylation factor 1 (Arf1) is an essential N-myristoylated 21-kDa GTP-binding protein with activities that include the regulation of membrane traffic and phospholipase D activity. Both the N terminus of the protein and the N-myristate bound to glycine 2 have previously been shown to be essential to the function of Arf in cells. We show that the bound nucleotide affects the conformation of either the N terminus or residues of Arf1 that are in direct contact with the N terminus. This was demonstrated by examining the effects of mutations in this N-terminal domain on guanosine 5'-O-(3-thio)triphosphate (GTP gamma S) and GDP binding and dissociation kinetics. Arf1 mutants, lacking 13 or 17 residues from the N terminus or mutated at residues 3-7, had a greater affinity for GTP gamma S and a lower affinity for GDP than did the wild-type protein. As the N terminus is required for interactions with target proteins, we conclude that the N terminus of Arf1 is a GTP-sensitive effector domain. When Arf1 was acylated, the GTP-dependent conformational changes were codependent on added phospholipids. In the absence of phospholipids, myristoylated Arf1 has a lower affinity for GTP gamma S than for GDP, and in the presence of phospholipids, the myristoylated protein has a greater affinity for GTP gamma S than for GDP. Thus, N-myristoylation is a critical component in the construction of this phospholipid- and GTP-dependent switch.

Resistance of highly branched (1-->3)-beta-D-glucans to formolysis

Small molecular weight (MW) glucan derivatives could be a useful tool for studying the mechanisms of beta-glucan mediated biological activity, especially as antagonists for a beta-glucan receptor. This paper described the stability of various (1-->6) branched (1-->3)-beta-D-glucans to formolysis in the preparation of small MW derivatives. The glucans used were curdlan (linear), pachyman (few branches), GRN (one branch in every third main chain unit; 2/6), SPG (2/6), SSG (3/6), and OL-2 (4/6). Curdlan and pachyman were easily degraded to oligosaccharides by degradation for 20 min at 100 degrees C by 90% formic acid. However, branched glucans, especially the highly branched glucans, SSG and OL-2, were significantly resistant to degradation, and the majority remained high MW. SSG required a longer period and/or a higher temperature (121 degrees C treatment) to produce small MW derivatives. Branched glucans were also resistant to zymolyase (an endo-(1-->3)-beta-D-glucan hydrolase) digestion. These facts suggest that the (1-->6)-beta-D-branched residues contribute to the glucans' resistance to formic acid degradation and zymolyase digestion.

Mechanism of human polymorphonuclear leukocyte adhesion to serum-treated corneocytes

The accumulation of polymorphonuclear leukocytes (PMN) beneath the stratum corneum is a characteristic histopathologic finding in various aseptic pustular dermatoses. To elucidate the pathomechanism involved in this phenomenon, we investigated whether PMN also attach to a sheet of corneocytes in vitro. A 1-cm2 corneocyte sheet was attached to a sterile glass slide with double adhesive tape used for skin graft surgery before incubating with human serum. The PMN suspension then was applied to the sheet. Attached cells were stained with May-Grunwald-Giemsa and counted with a computer image analyzer. We quantitatively assessed PMN adhesion to the serum-treated corneocyte sheets, which was mediated by activation of the alternative complement pathway. Addition of either anti-CD18 or anti-CD11b antibody to the assay system resulted in a marked reduction of PMN adhesion. We also demonstrated immunohistochemically that iC3b was formed on the serum-treated corneocytes. These findings suggest that PMN attach to serum-treated corneocytes through an interaction of CR3 expressed on PMN with iC3b-coated corneocytes. In addition, we found that this adhesion was enhanced by activation of PMN with phorbol myristate acetate. From these results, we speculate that complement activation by corneocytes occurs in the cutaneous lesions of aseptic pustular dermatoses and that PMN can be stimulated by the interaction with iC3b-opsonized corneocytes as well as by chemotaxins, leading to damage of the surrounding epidermal keratinocytes.

Mutational analysis of Saccharomyces cerevisiae ARF1

Wild type and eight point mutants of Saccharomyces cerevisiae ARF1 were expressed in yeast and bacteria to determine the roles of specific residues in in vivo and in vitro activities. Mutations at either Gly2 or Asp26 resulted in recessive loss of function. It was concluded that N-myristoylation is required for Arf action in cells but not for either nucleotide exchange or cofactor activities in vitro. Asp26 (homologous to Gly12 of p21ras) was essential for the binding of the activating nucleotide, guanosine 5'-3-O-(thio)triphosphate. This is in marked contrast to results obtained after mutagenesis of the homologous residue in p21ras or Gs alpha, and suggests a fundamental difference in the guanine nucleotide binding site of Arf with respect to these other GTP-binding proteins. Two dominant alleles were also identified, one activating dominant ([Q71L]Arf1) and the other ([N126I]) a negative dominant. A conditional allele, [W66R]Arf1, was characterized and shown to have approximately 300-fold lower specific activity in an in vitro Arf assay. Two high-copy suppressors of this conditional phenotype were cloned and sequenced. One of these suppressors, SFS4, was found to be identical to PBS2/HOG4, recently shown to encode a microtubule-associated protein kinase kinase in yeast.