Immunohistological and immunoelectron microscopic identification of TNF alpha in normal human and murine epidermis

Tumor necrosis factor-alpha and interleukin-1 antagonists alleviate inflammatory skin changes associated with epidermal growth factor receptor antibody therapy in mice

Cancer patients receiving epidermal growth factor receptor (EGFR) antibody therapy often experience an acneiform rash of uncertain etiology in skin regions rich in pilosebaceous units. Currently, this condition is treated symptomatically with very limited, often anecdotal success. Here, we show that a monoclonal antibody targeting murine EGFR, ME1, caused a neutrophil-rich hair follicle inflammation in mice, similar to that reported in patients. This effect was preceded by the appearance of lipid-filled hair follicle distensions adjacent to enlarged sebaceous glands. The cytokine tumor necrosis factor-alpha (TNFalpha), localized immunohistochemically to this affected region of the pilosebaceous unit, was specifically up-regulated by ME1 in skin but not in other tissues examined. Moreover, skin inflammation was reduced by cotreatment with the TNFalpha signaling inhibitor, etanercept, indicating the involvement of TNFalpha in this inflammatory process. Interleukin-1, a cytokine that frequently acts in concert with TNFalpha, is also involved in this process given the efficacy of the interleukin-1 antagonist Kineret. Our results provide a mechanistic framework to develop evidence-based trials for EGFR antibody-induced skin rash in patients with cancer.

Early up-regulation of Th2 cytokines and late surge of Th1 cytokines in an atopic dermatitis model

We investigated cytokine profiles in interleukin (IL)-4 transgenic (Tg) mice with a skin inflammatory disease resembling human atopic dermatitis. cDNA microarray revealed that the mRNAs encoding IL-1beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-13, tumour necrosis factor (TNF)-alpha, TNF-beta and interferon (IFN)-gamma were up-regulated in the skin of late lesion Tg mice and to a lesser degree in non-lesion Tg mice when compared to those of non-Tg mice. Real time reverse transcription-polymerase chain reaction (RT-PCR) analyses indicated that the cDNA copy numbers of IL-1beta, IL-4, IL-6, IL-10, TNF-alpha and IFN-gamma from the skin of late, early and non-lesions increased significantly compared to non-Tg mice. IL-2 and IL-12p40 cDNA copy numbers were increased significantly in early, but not late, lesions. Interestingly, IL-1beta, IL-3, IL-4, IL-5, IL-6, IL-10, IL-13, TNF-alpha, and IFN-gamma cDNAs were increased significantly the skin of before-onset and/or non-lesion mice. Flow cytometry analyses demonstrated an increased percentage of keratinocytes producing IL-4 as the disease progressed. The percentage of IL-2, IL-4, IL-10 and IFN-gamma-producing T cells and IL-12-producing antigen-presenting cells in skin-draining lymph nodes and inflammatory skin also increased, particularly in mice with late lesion. These results suggest that disease induction is primarily triggered by Th2 cytokines and that Th1, Th2 and non-Th proinflammatory cytokines are all involved in the disease process.

Characterization of the progressive skin disease and inflammatory cell infiltrate in mice with inhibited NF-kappaB signaling

A growth inhibitory role in skin development for the NF-kappaB proteins has been established in recent years. We have previously shown that inhibition of NF-kappaB by overexpression of degradation-resistant IkappaB-alpha in the skin results in the development of squamous cell carcinomas (SCC). In this paper, we characterize the progressive skin disease leading to cancer development in mice with inhibited NF-kappaB signaling in the skin. Increased proliferation and a strong inflammatory response were evident in transgenic skin. A mixed inflammatory cell infiltrate dominated by polymorphonuclear leukocytes was observed in concurrence with an upregulation of the proinflammatory cytokine tumor necrosis factor-alpha. This genetically engineered mouse mutation may be a useful tool to test the efficacy of cytokine therapies for SCC in the future.

CD1a and CD1c cell sorting yields a homogeneous population of immature human Langerhans cells

There is increasing evidence that ex vivo generated Langerhans cells (LCs) cannot fully substitute for their physiological counterparts in normal epidermis when studying the immunobiology of this prototype of a tissue-residing immature dendritic cell (DC). Here, we present CD1-based magnetic-activated cell-sorting (MACS) protocols for the effective isolation of human epidermal LCs. CD1c selection yielded a homogeneous population of pure and viable HLA-DR(+)/CD1a(+) DCs, with the ultrastructural features, surface antigen expression and cytokine profile, characteristic of epidermis-resident immature LCs. The immature state and functional integrity were established by allogeneic mixed lymphocyte reactions showing a weak stimulatory capacity of freshly isolated cells and upregulation upon stimulation. Characterizing the cells in more detail, we could demonstrate for the first time that normal human LCs express CXCR4, CD40 ligand (CD40L), and Fas and Fas ligand (FasL). The observed constitutive transcription of TGF-beta suggests that the viability and immature state of epidermal LCs are maintained not only by the TGF-beta production from the microenvironment, but also in an autocrine or paracrine manner. LPS and IFN-omega stimulated the expression of the inflammatory cytokines TNF-alpha and IL-1beta, and there was secretion of IL-12p70 after CD40 ligation. Remarkably, the CD1-sorted LCs showed no loss of their Birbeck granules and CD1a expression upon culturing and no spontaneous phenotypic and functional maturation into potent antigen-presenting cells (APCs). We conclude that human epidermal LCs obtained by the CD1c cell-sorting protocol are optimal candidates with which to elucidate the properties and capabilities of immature cells and to develop immunotherapeutic vaccines.

Keratins and the keratinocyte activation cycle

In wound healing and many pathologic conditions, keratinocytes become activated: they turn into migratory, hyperproliferative cells that produce and secrete extracellular matrix components and signaling polypeptides. At the same time, their cytoskeleton is also altered by the production of specific keratin proteins. These changes are orchestrated by growth factors, chemokines, and cytokines produced by keratinocytes and other cutaneous cell types. The responding intracellular signaling pathways activate transcription factors that regulate expression of keratin genes. Analysis of these processes led us to propose the existence of a keratinocyte activation cycle, in which the cells first become activated by the release of IL-1. Subsequently, they maintain the activated state by autocrine production of proinflammatory and proliferative signals. Keratins K6 and K16 are markers of the active state. Signals from the lymphocytes, in the form of Interferon-gamma, induce the expression of K17 and make keratinocytes contractile. This enables the keratinocytes to shrink the provisional fibronectin-rich basement membrane. Signals from the fibroblasts, in the form of TGF-beta, induce the expression of K5 and K14, revert the keratinocytes to the healthy basal phenotype, and thus complete the activation cycle.

Thioredoxin, thioredoxin reductase and tumour necrosis factor-alpha expression in melanoma cells: correlation to resistance against cytotoxic attack

Although malignant melanomas are often associated with cytotoxic lymphocyte infiltration, these cells are largely ineffective in inducing tumour cell kill, indicating that the melanoma cells have protective mechanisms. These mechanisms are not fully understood, but cytokines and redox-active antioxidant proteins such as catalase, superoxide dismutase, thioredoxin (Trx) and Trx reductase (TrxR) present in the tumour cells constitute part of this protection. In this study firstly we investigated the constitutive intracellular expression of Trx, TrxR, the cytokines interleukin (IL)-1alpha, IL1beta, IL2, IL4, IL6, IL8, IL10, tumour necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) in normal melanocytes and ten primary and metastatic malignant melanoma cell lines. Secondly, we analysed whether redox stimulation by Trx alone or in combination with the phorbol ester PMA affected the expression and release of TNFalpha. Thirdly, we explored the possible correlation between Trx/TrxR expression and resistance to exogenous TNFalpha. All the cultured cells showed intracellular overexpression of Trx and TrxR, which was not always the case for melanoma cells in vivo (tissue sections). The predominant intracellular cytokines found were TNFalpha, IL1alpha and IL1beta. In spite of its presence in the Golgi apparatus, none of the cell lines secreted TNFalpha constitutively, and only one melanoma, FM3, released detectable amounts after stimulation. In contrast, U-937 monocyte control cells released high amounts of TNFalpha on identical stimulation. All the melanoma cell lines were relatively resistant against exogenous TNFalpha, and there was a significant correlation (P < 0.01) between intracellular Trx/TrxR expression and TNFalpha resistance (IC50). In conclusion, Trx and TrxR, as well as TNFalpha, IL1alpha and IL1beta, were highly expressed in cultured normal skin melanocytes and malignant melanoma cell lines. In contrast to U-937 monocytic cells, TNFalpha showed a secretory block in these cells, suggesting a cytoprotective and possible autocrine role for TNFalpha. The intracellular expression of Trx and TrxR together with endogenous TNFalpha was correlated with the resistance to TNFalpha-induced cytotoxicity.

The antigen-presenting environment in normal and human papillomavirus (HPV)-related premalignant cervical epithelium

The activation of HPV-specific T cells within the cervical microenvironment is likely to play an important part in the natural history of cervical intraepithelial neoplasia (CIN). The extent and the type of T cell activation will depend critically on the expression of MHC, costimulatory cell surface molecules and cytokines by keratinocytes and Langerhans cells within the cervical lesion. Expression of MHC class II (HLA-A-DR and -DQ), costimulatory/adhesion molecules (CD11a/18, CD50, CD54, CD58 and CD86) and cytokines (tumour necrosis factor-alpha (TNF-alpha) and IL-10) was therefore investigated by immunohistochemistry in normal squamous epithelium (n = 12), low-grade (n = 23) and high-grade (n = 18) squamous intraepithelial lesions of the cervix. CIN progression was associated with de novo expression of HLA-DR and CD54, and increased expression of CD58 by keratinocytes. However, significantly, there was no expression of any adhesion/costimulation molecule by epithelial Langerhans cells in any cervical biopsy studied. Furthermore, TNF-alpha, a potent activator of Langerhans cells, was expressed constitutively by basal keratinocytes in normal cervix (12+/12). but expression of this cytokine was absent in a number of CIN samples (20+/23 for low-grade, 12+/18 for high-grade CIN). Conversely, the suppressive cytokine IL-10 was absent in normal epithelium (0+/12), but was up-regulated in a number of CIN lesions (12+/23 for low-grade; 8+/18 for high-grade CIN). The restricted expression of costimulation/adhesion molecules and the nature of the cytokine microenvironment within the epithelium may act to limit effective immune responses in some CIN lesions.

Epidermal signal transduction and transcription factor activation in activated keratinocytes

In the area of biology, many laboratories around the world are dissecting and characterizing signal transduction mechanisms and transcription factors responsive to various growth factors and cytokines, in various cell types. However, because of the differences in systems used, it is not clear whether these systems coexist, whether they interact meaningfully, and what their relative roles are. Epidermal keratinocytes are the perfect cell type in which to integrate this knowledge, because in these cells these mechanisms are known to be relevant. Keratinocytes both produce and respond to growth factors and cytokines, especially in pathological conditions and during wound healing, when the physiology of keratinocytes is altered in a way specified by the presence of a subset growth factors and cytokines. In fact, growth factors and cytokines cause the major changes in gene expression and keratinocyte behavior in various cutaneous diseases. In some cases, such as in wound healing, these responses are highly beneficial; in others, such as in psoriasis, they are pathological. It is not clear at present which are operating in which conditions, which are important for the healing process and which are harmful. Growth factors and cytokines affect keratinocytes sometimes simultaneously, at other times individually. In this manuscript we describe the signal transduction pathways responsible for the effects of interferons, the EGF/TGF alpha family and the TNF alpha/IL-1 family of signaling molecules. We also describe the important transcription factors known to be functional in epidermis, with particular emphasis on those factors that are activated by growth factors and cytokines. Finally, we describe what is known about transcriptional regulation of keratin genes, especially those specifically expressed in pathological processes in the epidermis. We expect that the enhanced understanding of the pathways regulating gene expression in keratinocytes will identify the pharmacological targets, the signal transducing proteins and the corresponding transcription factors, used by growth factors and cytokines. This research will led to development of compounds precisely aimed at those targets, allowing us to isolate and inhibit the harmful side effects of growth factors and cytokines. Such compounds should lead to highly specific and therefore more effective treatments of the cutaneous disorders in which these pathways play significant roles.

Expression of neurotrophic factors and neuropeptide receptors by Langerhans cells and the Langerhans cell-like cell line XS52: further support for a functional relationship between Langerhans cells and epidermal nerves

Epidermal Langerhans cells are frequently anatomically associated with calcitonin gene-related peptide-containing nerves. Furthermore, calcitonin gene-related peptide inhibits Langerhans cells antigen-presenting function in several assays. Studies were performed to further explore the hypothesis that Langerhans cells and nerves have a functional relationship. To examine whether Langerhans cells may produce factors that influence nerve cell differentiation, we utilized the Langerhans cell-like cell line XS52 as a surrogate for Langerhans cells and compared it with Langerhans cells enriched to 90%. Supernatants conditioned by lipopolysaccharide-stimulated XS52 cells were able to induce the differentiation of the pheochromocytoma line PC12 into sympathetic neuron-like cells. This was also the case with enriched Langerhans cells stimulated by lipopolysaccharide. Pretreatment of conditioned supernatants with specific neutralizing anti-sera indicated that most of the differentiation-inducing activity was due to interleukin-6 and a small amount was due to nerve growth factor and basic fibroblast growth factor. By reverse transcriptase polymerase chain reaction, three clones of the XS52 cell line, XS52-4D, XS52-11D, and XS52-8B, were found to express mRNA for interleukin-6 and expression was markedly augmented by lipopolysaccharide. mRNA for nerve growth factor and basic fibroblast growth factor was detected in XS52-4D and XS52-11D, but not in XS52-8B. The expression of these neurotrophic factors by enriched Langerhans cells was quite similar to that of XS52-4D. In order to examine whether Langerhans cells may express receptors for nerve-derived peptides, reverse transcriptase polymerase chain reaction was employed to look for pituitary adenylate cyclase activating polypeptide type I, type II, and type III, and gastrin-releasing peptide receptors. All clones examined, as well as enriched Langerhans cells, expressed pituitary adenylate cyclase activating polypeptide type II and type III, and gastrin-releasing peptide receptors. These results suggest bi-directional signalling between Langerhans cells and nerves; nerve cells may regulate Langerhans cell function by elaboration of certain neuropeptides whereas Langerhans cells may promote the differentation of nerves by elaboration of interleukin-6 and, possibly, other factors.

1alpha,25-dihydroxyvitamin D3 induces sphingomyelin hydrolysis in HaCaT cells via tumor necrosis factor alpha

Treatment of the human keratinocyte cell line HaCaT with 1alpha, 25-dihydroxyvitamin D3 (1,25-(OH)2D3) resulted in the hydrolysis of sphingomyelin with peak elevations of ceramide levels after 2-3 h (Geilen, C. C., Bektas, M., Wieder, Th., and Orfanos, C. E. (1996) FEBS Lett. 378, 88-92). In the present paper, the mechanism underlying the effect of 1,25-(OH)2D3 on sphingomyelin hydrolysis was investigated. Using the cell culture supernatant of HaCaT cells treated with 1,25-(OH)2D3 for 2 h, it was possible to induce sphingomyelin hydrolysis as early as 30-60 min after addition to resting cells. Several lines of experimental evidence indicated that tumor necrosis factor alpha (TNFalpha) mediates sphingomyelin hydrolysis after 1,25-(OH)2D3 treatment: (i) 1,25-(OH)2D3 stimulated TNFalpha mRNA expression after 1 h, (ii) newly synthesized TNFalpha occurred 2 h after 1,25-(OH)2D3 treatment, (iii) indirect activation of sphingomyelin hydrolysis by the supernatant of 1, 25-(OH)2D3-treated HaCaT cells was abolished by preincubation of the supernatant with antibodies directed against TNFalpha, and (iv) preincubation of HaCaT cells with neutralizing antibodies directed against the 55-kDa receptor of TNFalpha blocked the ability of 1, 25-(OH)2D3 to induce sphingomyelin hydrolysis in HaCaT cells. These data demonstrate that 1,25-(OH)2D3 activated sphingomyelin hydrolysis by an autocrine mechanism via TNFalpha expression. Furthermore, this indirect mode of action may serve as an explanation for the delayed induction of sphingomyelin hydrolysis by vitamin D3.

Proinflammatory cytokines and their corresponding receptor proteins in eccrine sweat glands in normal and cutaneous leishmaniasis human skin. An immunohistochemical study

Paraformaldehyde-fixed biopsy specimens of normal and chronic cutaneous leishmaniasis human skin were investigated for the presence and cellular distribution of interleukin-1 alpha, interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha and the corresponding receptors in eccrine sweat glands, using an indirect immunoperoxidase technique. There was cytoplasmic staining for all 4 cytokines as well as their receptor proteins in the clear cells of the eccrine sweat glands of both normal and inflamed skin specimens. No staining could be seen in the dark cells or the myoepithelial cells, neither in normal nor in inflamed skin. However, a difference between normal and inflamed skin was observed in the ductal system. Thus, cell layers of the dermal ducts in leishmaniasis skin were stained for all 4 cytokines, with more intense labelling in the basal cell layer of the coiled ducts, while in the normal skin, an intense staining was more evident in the inner luminal layer, with variable and less intense labelling of the basal layer. The immunolabelling for the cytokine receptors within the dermal ducts exhibited similar staining intensity in both luminal and basal cell layers, except in the case of the IL-6 receptor, which showed a moderate to intense signal in the basal cell layer but a weak staining of the luminal cell layer. Infiltrating inflammatory cells around the sweat gland apparatus in leishmaniasis skin exhibited immunoreactivities for all cytokines and their corresponding receptors.

Enhanced cytokine production and collagen synthesis of gingival fibroblasts from patients with denture fibromatosis

The mechanisms of denture-induced gingival hypertrophy remain to be explored. Since fibroblast proliferation and bone resorption characterize this disorder, the possible involvement of cytokines was investigated. Gingival fibroblasts were obtained from six patients with denture fibromatosis (Den-Fb) and six healthy persons (Nor-Fb). Cells were compared for proliferation, collagen synthesis, and cytokine production. Incorporation of [3H]thymidine (TdR) was increased in 3 Den-Fb and 3 Nor-Fb lines in the presence of interleukin-1-beta (IL-1 beta) (10 U/mL) and tumor necrosis factor-alpha (TNF-alpha) (from 10 to 100 U/mL). Proline incorporation in Den-Fb was higher than that in Nor-Fb, and the mean collagen synthesis level in Den-Fb was significantly higher than that in Nor-Fb. Although there was no difference between the up-regulation of protein synthesis in Den-Fb and Nor-Fb induced by IL-1 beta or TNF-alpha, the receptors for these cytokines were expressed at higher levels in cell lines which exhibited higher protein synthesis. Between Nor-Fb and Den-Fb, there was no difference in the generation of granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-6 (IL-6). However, most Den-Fb produced more GM-CSF and IL-6 in the presence of TNF-alpha. Enhancement of IL-6 generation by GM-CSF was also more prominent in Den-Fb. GM-CSF and IL-6 were synergistically generated after co-culture of the fibroblasts with gingival keratinocytes. GM-CSF and IL-6 generation of Den-Fb was markedly enhanced by co-culture of Den-Fb with peripheral blood mononuclear cells (PBMC), especially PBMC from patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of cytokines by human melanoma cells and melanocytes

Experimental animal models have shown that various cytokines, depending of their specific properties, may support growth and metastasis of tumor cells or even lead to tumor rejection. The analysis of expression of cytokine genes by melanoma cell lines indicated that melanoma cells constitutively produce both autostimulatory and inhibitory cytokines. Using reverse transcriptase polymerase chain reaction analysis, simultaneous expression of several cytokines, including interleukin-1 beta (IL-1 beta), IL-6, IL-8, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor, by melanoma cells was found. The same cytokine transcripts were detected in melanocytes, suggesting that cells of the melanocytic lineage express a specific pattern of cytokines in vitro. All these cytokines are known to be able to stimulate effector cells of the host. Additionally, production of mRNA for IL-10, a cytokine with potential immunosuppressive properties, was detected in melanoma cells and melanocytes. These and other cytokines are likely to be involved in the immune response to cancer and at this time it is unknown what the net effects of multiple cytokines are on the outcome of the host response to tumor.

Permeability barrier disruption alters the localization and expression of TNF alpha/protein in the epidermis

Previous studies have shown that (1) epidermal TNF alpha mRNA levels are increased following acute disruption of the cutaneous permeability barrier; (2) this increase is maximal at 1 h and decreases to control levels by 8 h; and (3) in essential fatty acid-deficient (EFAD) mice, a chronic model of barrier perturbation, TNF alpha mRNA levels are also elevated several-fold over controls. In the present study we determined, using immunocytochemical procedures, epidermal TNF alpha protein levels following either acute of chronic barrier disruption and the localization of any increase. Frozen, paraffin and Antibed sections of skin were incubated with polyclonal anti-mouse TNF alpha antisera and detection was accomplished by either immunoperoxidase or fluorescence procedures. We found that (1) TNF alpha-immunoreactive protein was present in normal mouse epidermis, and was primarily localized to the upper nucleated layers where it displayed a diffuse cytosolic pattern; (2) acute disruption of the barrier with acetone or tape-stripping resulted in TNF alpha staining that was more intense throughout all of the nucleated epidermal cell layers in comparison with normal epidermis; (3) the increase in TNF alpha staining occurred as early as 2 h after barrier disruption; and (4) increased TNF alpha staining was also observed in the stratum corneum of EFAD mice. These results indicate that epidermal TNF alpha protein levels increase after both acute and chronic barrier disruption, and are consistent with the hypothesis that TNF alpha may signal and/or coordinate portions of the cutaneous response to barrier disruption.