Induced keratinocyte hyper-proliferation in alpha2beta1 integrin transgenic mice results in systemic immune cell activation.

alpha2beta1 integrins are normally confined to the proliferating basal layers of the epidermis. However, during wound healing and in psoriasis, these integrins are expressed on keratinocytes in suprabasal layers correlating with a less differentiated phenotype. Transgenic mice expressing alpha2beta1 integrins under the involucrine promoter have previously been demonstrated, to various degrees, spontaneously develop a skin disorder resembling psoriasis. Herein, we show that a mild epidermal wounding induces a uniform acanthosis together with an influx of immune cells. The disease initiates as a normal wound healing process and is completely restored in wildtype mice by day 14. However, in the integrin transgenic mice a chronic inflammation develops, a process that can be compared to the Koebner phenomenon in psoriatic patients. In this study, we have followed the integrin transgenic mice for five weeks, where substantial keratinocyte hyper-proliferation, inflammatory infiltration and high cytokine levels within the skin can still be observed. In addition, draining lymph nodes were dramatically increased in size and contained highly activated T cells, as well as APCs secreting large amounts of pro-inflammatory cytokines. Furthermore, the systemic immune response was affected with increased spleen size, elevated cytokine levels in the serum and altered lymphocyte trafficking patterns, very much resembling what is seen in psoriasis patients. Finally, CD4(+) T cell depletion was not able to affect the onset or progression of skin inflammation. This suggests that altered keratinocyte differentiation and proliferation can drive a skin inflammation and cause chronic immune cell activation both at a local and systemic level.

Application of stereology to dermatological research.

Stereology is a set of mathematical and statistical tools to estimate three-dimensional (3-D) characteristics of objects from regular two-dimensional (2-D) sections. In medicine and biology, it can be used to estimate features such as cell volume, cell membrane surface area, total length of blood vessels per volume tissue and total number of cells. The unbiased quantification of these 3-D features allows for a better understanding of morphology in vivo compared with 2-D methods. This review provides an introduction to the field of stereology with specific emphasis on the application of stereology to dermatological research by supplying a short insight into the theoretical basis behind the technique and presenting previous dermatological studies in which stereology was an integral part. Both the theory supporting stereology and a practical approach in a dermatological setting are reviewed with the aim to provide the reader with the capability to better assess papers employing stereological estimators and to design stereological studies independently.

Regulatory T cells control VEGF-dependent skin inflammation.

Transgenic mice expressing vascular endothelial growth factor (VEGF) under the keratin 14 promoter have been described to develop a psoriasis-like inflammation characterized by increased angiogenesis, acanthosis, and immune cell infiltration. We have recently shown that applying 12-O-tetradecanoylphorbol-13-acetate (TPA) in these mice induces a severe and long-lasting skin inflammation with a Th17 cell signature. Here, we aimed to study the function of CD4(+) T cells using this model. Lymphocytes isolated from inflamed ears showed a significantly higher number of activated T cells, in contrast to the primarily naive lymphocytes isolated from blood. In addition, there was an increase in regulatory T cells (CD4(+)CD25(+)CD127(-/low)) within the skin. To clarify the function of CD4(+) cells, we depleted CD4(+) T cells using antibody. CD4 depletion resulted in augmented ear thickness and proinflammatory cytokine levels, indicating that CD4(+) T cells have a suppressive rather than a proinflammatory function in this model. Subsequently, sorted regulatory CD4(+)CD25(+) T cells were transferred to naive K14/VEGF transgenic mice before TPA challenge. CD4(+)CD25(+) T-cell transfer significantly reduced ear thickness and proinflammatory cytokine production compared to controls. This shows that a persistent skin inflammation with similarities to psoriasis can be controlled by a single injection of few regulatory T cells.

TPA induction leads to a Th17-like response in transgenic K14/VEGF mice: a novel in vivo screening model of psoriasis.

Psoriasis is a common chronic inflammatory skin disease, characterized by epidermal hyperplasia, immune cell infiltration, increased dermal angiogenesis and local up-regulation of a variety of inflammatory mediators. Psoriasis is thought to be driven primarily by CD4(+) T cells with a T(h)1 and/or T(h)17 phenotype. Transgenic keratin 14 (K14)/vascular endothelial growth factor (VEGF) mice have previously been reported to develop a psoriasis-like phenotype. The aim of this study was to further characterize the model for validation as an in vivo screening model of psoriasis. Inflammation was induced in the ear skin with five topical applications of 12-O-tetradecanoyl phorbol-13-acetate (TPA) and a significantly increased inflammation was found in TPA-induced K14/VEGF transgenic animals compared with wild-type mice. The amount of VEGF in the ear tissue was significantly elevated resulting in increased dermal angiogenesis. Furthermore, intense epidermal hyperplasia, CD3(+) infiltration and significantly increased amounts of (TNF) tumor necrosis factor alpha, IL-1 beta, IL-6, IL-12/23p40, IL-12p70, IL-22 and IL-17 were detected in the inflamed ear skin. This cytokine profile strongly suggests a T(h)17-mediated inflammation. All findings were a result of induced over-expression of VEGF. Topical treatment with betamethasone-17-valerate (BMS) significantly reduced ear skin inflammation and epidermal hyperplasia and also decreased the CD3(+) infiltration. In conclusion, the TPA-induced phenotype in K14/VEGF animals displayed several features of psoriasis, including a T(h)17 cytokine profile and a chronic-like progression, and can be used as an in vivo screening model of psoriasis.

Autometallographic tracing of mercury in pilot whale tissues in the Faroe Islands.

OBJECTIVES: Autometallography (AMG) was applied for tracing mercury in long-finned pilot whales (Globicephala melas) harvested in the Faroe Islands. RESULTS: Ample mercury accumulation was found in kidney tubules, in contrast to the largely unstained glomeruli. Hepatocytes, as well as liver macrophages, exhibited high mercury uptake. The muscle tissue accumulated only scant amounts of mercury, primarily around the nuclei of the striated muscle cells. At the ultrastructural level, mercury was found to accumulate intracellularly in lysosomes, and extracellularly in the basement membranes of vessels. The results were verified by proton induced X-ray emission (PIXE) analysis, and it was established that the tissue contained no other AMG traceable metals. CONCLUSION: The use of AMG analysis on autopsies and biopsies is suggested as a tool for evaluating mercury pollution.

High circulating levels of tumor necrosis factor-alpha in centenarians are not associated with increased production in T lymphocytes.

BACKGROUND: Aging is characterized by increased inflammatory activity reflected by increased plasma levels of proinflammatory cytokines, concomitant with an altered cytokine profile of T lymphocytes. High plasma levels of tumor necrosis factor (TNF)-alpha are strongly associated with morbidity and mortality in elderly humans. However, the cellular source and mechanisms for the increased circulating TNF-alpha levels are unknown. OBJECTIVE: The aim of the present study was to investigate if high plasma levels of TNF-alpha are associated with increased production of TNF-alpha by T lymphocytes in elderly humans. METHODS: TNF-alpha production by CD4+ and CD8+ T lymphocytes was measured by flow cytometry following stimulation with phorbol 12-myristate 13-acetate and ionomycin in 28 young controls, 14, 81-year-olds and 25 centenarians. RESULTS: Plasma levels of TNF-alpha increased with increasing age. An increased percentage and number of T lymphocytes from the 81 year olds expressed TNF-alpha, whereas centenarians did not show this altered TNF-alpha secretion profile. CONCLUSION: T cells may contribute to the elevated levels of plasma TNF-alpha in healthy elderly subjects, whereas other mechanisms are responsible in very old individuals.

Pneumococcal infections in humans are associated with increased apoptosis and trafficking of type 1 cytokine-producing T cells.

Streptococcus pneumoniae infections are associated with considerable morbidity and mortality throughout the world. The immunopathology is characterized by an intense inflammatory reaction, including a strong acute-phase response and increased numbers of neutrophils in the circulation. However, little is known regarding the T-cell response during in vivo infections in humans. The purpose of this study was to test the hypothesis that activated T cells producing type 1 cytokines were engaged in the host response to pneumococcal infections. The phenotype and function of T cells were studied in 22 patients at admission to a department of infectious diseases and after antibiotic treatment for 1 week compared with an age-matched, healthy control group. Pneumococcal infections induced lymphopenia in the circulation due to the disappearance of activated T lymphocytes with a type 1 cytokine profile. In contrast, the numbers of naive T cells and interleukin-4-producing T cells did not change. Activated type 1 cytokine-producing cells reappeared in the circulation in relation to the treatment and clinical improvement. The underlying mechanisms during infection may include sequestration in the peripheral tissues and/or apoptosis. In fact, increased activation-induced apoptosis in the remaining peripheral lymphocytes and elevated levels of soluble Fas ligand were detected at admission to the hospital. In conclusion, these data suggest that activated T lymphocytes with a type 1 cytokine profile are highly engaged in the in vivo immune response to S. pneumoniae.

Increased levels of soluble CD30 in plasma of patients with Plasmodium falciparum malaria.

Levels of soluble CD30 (sCD30) in serum were elevated in patients with Plasmodium falciparum malaria but showed decline following treatment. The levels of sCD30 in serum were correlated significantly with the expression of gamma interferon by peripheral T cells. These data suggest that CD30(+) cells are upregulated during a malaria attack and that they may play a regulating role at the site of inflammation.

Chalcones from Chinese liquorice inhibit proliferation of T cells and production of cytokines.

Licochalcone A (LicA), an oxygenated chalcone, has been shown to inhibit the growth of both parasites and bacteria. In this study, we investigated the effect of LicA and four synthetic analogues on the activity of human peripheral blood mononuclear cell proliferation and cytokine production. Four out of five chalcones tested inhibited the proliferation of lymphocytes measured by thymidine incorporation and by flow cytometry. The production of pro- and anti-inflammatory cytokines from monocytes and T cells was also inhibited by four of five chalcones. Furthermore, intracellular detection of cytokines revealed that the chalcones inhibited the production rather than the release of the cytokines. Taken together, these results indicate that LicA and some analogues may have immunomodulatory effects, and may thus be candidates not only as anti-microbial agents, but also for the treatment of other types of diseases.

Acute P. falciparum malaria induces a loss of CD28- T IFN-gamma producing cells.

P. falciparum malaria is associated with increased activation among peripheral lymphocytes. In the present study, we investigated markers of susceptibility to apoptosis and expression of IFN-gamma and IL-4 by CD28-and CD28+T cells in West African children with acute P. falciparum malaria. The study showed increased susceptibility to apoptosis and cytokine production among T lymphocytes during acute malaria but also that T cells, in particular IFN-gamma producing CD28-T cells, were substantially reduced. These results are in line with previous studies suggesting that certain T cell subsets are sequestered away from the peripheral blood during P. falciparum malaria.