Involvement of IL-9 in Th17-associated inflammation and angiogenesis of psoriasis.

It is thought that a Th1/Th17-weighted immune response plays a predominant role in the pathogenesis of psoriasis. Our findings now indicate a link between IL-9, a Th2 and Th9 cytokine, and Th17 pathway in psoriasis. In K5.hTGF-ß1 transgenic mice, exhibiting a psoriasis-like phenotype, we found increased IL-9R and IL-9 expression in the skin and intradermal IL-9 injection induced Th17-related inflammation. IL-9 also promoted angiogenesis and VEGF and CD31 overexpression in mice in vivo and increased tube formation of human endothelial cells in vitro. Injecting anti-IL-9 antibody into K5.hTGF-ß1 transgenic mice not only diminished inflammation (including skin infiltration by T cells, monocytes/macrophages, and mast cells) and angiogenesis but also delayed the psoriasis-like skin phenotype. Notably, injection of anti-psoriatic acting anti-IL-17 antibody reduced skin IL-9 mRNA and serum IL-9 protein levels in K5.hTGF-ß1 transgenic mice and prevented IL-9-induced epidermal hyperplasia and inflammation of the skin of wild type mice. In addition, we observed that IL-9R expression in lesional skin from psoriasis patients was markedly higher than in healthy skin from control subjects. Moreover, IL-9 significantly enhanced IL-17A production by cultured human peripheral blood mononuclear cells or CD4+ T cells, especially in psoriasis patients. Thus, IL-9 may play a role in the development of psoriatic lesions through Th17-associated inflammation and angiogenesis.

8-Methoxypsoralen plus UVA treatment increases the proportion of CLA+ CD25+ CD4+ T cells in lymph nodes of K5.hTGFß1 transgenic mice.

8-Methoxypsoralen plus UVA (PUVA) photochemotherapy is an effective treatment for many skin diseases including psoriasis. However, its exact mechanism of therapeutic action is incompletely understood. Previously, in K5.hTGFß1 transgenic psoriatic mice, we found that PUVA induces Foxp3+ CD25+ CD4+ regulatory T cells in both lymph node and spleen. Now, in the same model, we investigated whether cutaneous lymphocyte-associated antigen (CLA) mediates PUVA's effect on homing of CD25+ CD4+ T cells to the lymph nodes of K5.hTGFß1 transgenic mice. We found that a low dose of topical PUVA maximally increased the proportion of CLA + CD25+ CD4 + T cells in the lymph nodes by up to 8-fold. We also observed an increased number of Foxp3+ CD25+ T cells in the skin of the mice after PUVA treatment. Together, these findings suggest that PUVA affects the homing of regulatory T cells.

Downregulation of endothelial adhesion molecules by dimethylfumarate, but not monomethylfumarate, and impairment of dynamic lymphocyte-endothelial cell interactions.

Although fumaric acid esters (FAE) have a decade-long firm place in the therapeutic armamentarium for psoriasis, their pleiotropic mode of action is not yet fully understood. While most previous studies have focused on the effects of FAE on leucocytes, we have addressed their activity on macro- and microvascular endothelial cells. As detected both on mRNA and protein levels, dimethylfumarate effected a profound reduction of TNFα-induced expression of E-selectin (CD62E), ICAM-1 (CD54) and VCAM-1 (CD106) on two different endothelial cell populations in a concentration-dependent manner. This reduction of several endothelial adhesion molecules was accompanied by a dramatic diminution of both rolling and firm adhesive interactions between endothelial cells and lymphocytes in a dynamic flow chamber system. Dimethylfumarate, at a concentration of 50 µm, reduced lymphocyte rolling on endothelial cells by 85.9% (P<0.001 compared to untreated controls), and it diminished the number of adherent cells by 88% (P<0.001). In contrast, monomethylfumarate (MMF) influenced neither surface expression of adhesion molecules nor interactions between endothelial cells and lymphocytes. These observations demonstrate that endothelial cells, in addition to the known effects on leucocytes, undergo profound functional changes in response to dimethylfumarate. These changes are accompanied by severely impaired dynamic interactions with lymphocytes, which constitute the critical initial step of leucocyte recruitment to inflamed tissues in psoriasis and other TNF-related inflammatory disorders.

Platelet-activating factor blockade inhibits the T-helper type 17 cell pathway and suppresses psoriasis-like skin disease in K5.hTGF-ß1 transgenic mice.

Platelet-activating factor (PAF), a potent biolipid mediator, is involved in a variety of cellular transduction pathways and plays a prominent role in inducing inflammation in different organs. We used K5.hTGF-ß1 transgenic mice, which exhibit an inflammatory skin disorder and molecular and cytokine abnormalities with strong similarities to human psoriasis, to study the pathogenic role of PAF. We found that injecting PAF into the skin of transgenic mice led to inflammation and accelerated manifestation of the psoriatic phenotype by a local effect. In contrast, injecting mice with PAF receptor antagonist PCA-4248 lowered the PAF level (most likely by depressing an autocrine loop) and neutrophil, CD68(+) cell (monocyte/macrophage), and CD3(+) T-cell accumulation in the skin and blocked progression of the psoriasis-like phenotype. This effect of PAF blockade was specific and similar to that of psoralen-UV-A and was paralleled by a decrease in abnormally elevated mRNA and/or protein levels of T-helper type 17 cell-related cytokines IL-17A, IL-17F, IL-23, IL-12A, and IL-6 and its transcription factor signal transducer and activator of transcription 3. In contrast, PCA-4248 treatment up-regulated mRNA levels of cyclooxygenase-2 and IL-10 in dorsal skin and release of IL-10 in serum and skin. Interfering with PAF may offer the opportunity to develop novel therapeutic strategies for inflammatory psoriasis and associated comorbidities, including metabolic syndrome and atherosclerosis, in which the IL-17 axis may be involved.

Halting angiogenesis by non-viral somatic gene therapy alleviates psoriasis and murine psoriasiform skin lesions.

Dysregulated angiogenesis is a hallmark of chronic inflammatory diseases, including psoriasis, a common skin disorder that affects approximately 2% of the population. Studying both human psoriasis in 2 complementary xenotransplantation models and psoriasis-like skin lesions in transgenic mice with epidermal expression of human TGF-ß1, we have demonstrated that antiangiogenic non-viral somatic gene therapy reduces the cutaneous microvasculature and alleviates chronic inflammatory skin disorders. Transient muscular expression of the recombinant disintegrin domain (RDD) of metargidin (also known as ADAM-15) by in vivo electroporation reduced cutaneous angiogenesis and vascularization in all 3 models. As demonstrated using red fluorescent protein-coupled RDD, the treatment resulted in muscular expression of the gene product and its deposition within the cutaneous hyperangiogenic connective tissue. High-resolution ultrasound revealed reduced cutaneous blood flow in vivo after electroporation with RDD but not with control plasmids. In addition, angiogenesis- and inflammation-related molecular markers, keratinocyte proliferation, epidermal thickness, and clinical disease scores were downregulated in all models. Thus, non-viral antiangiogenic gene therapy can alleviate psoriasis and may do so in other angiogenesis-related inflammatory skin disorders.

8-methoxypsoralen plus ultraviolet A therapy acts via inhibition of the IL-23/Th17 axis and induction of Foxp3+ regulatory T cells involving CTLA4 signaling in a psoriasis-like skin disorder.

To elucidate the molecular action of 8-methoxypsoralen plus UVA (PUVA), a standard dermatological therapy, we used K5.hTGF-beta1 transgenic mice exhibiting a skin phenotype and cytokine abnormalities with strong similarities to human psoriasis. We observed that impaired function of CD4+CD25+ regulatory T cells (Tregs) and increased cytokine levels of the IL-23/Th17 pathway were responsible for the psoriatic phenotype in this mouse model. Treatment of K5.hTGF-beta1 transgenic mice with PUVA suppressed the IL-23/Th17 pathway, Th1 milieu, as well as transcription factors STAT3 and orphan nuclear receptor RORgammat. PUVA induced the Th2 pathway and IL-10-producing CD4+CD25+Foxp3+Tregs with disease-suppressive activity that was abolished by anti-CTLA4 mAb treatment. These findings were paralleled by macroscopic and microscopic clearance of the diseased murine skin. Anti-IL-17 mAb treatment also diminished the psoriatic phenotype of the mice. This indicated that both induced Tregs involving CTLA4 signaling and inhibition of the IL-23/Th17 axis are central for the therapeutic action of PUVA.

Modulating T cell functions does not alleviate chronic inflammatory skin lesions in K5.TGF beta 1 transgenic mice.

To use mice with chronic hyperproliferative skin inflammation as psoriasis models, their thorough phenotypic and functional characterization is indispensable. Mice with keratin 5 promoter-controlled overexpression of latent human Transforming Growth Factor (TGF)beta1 within the basal epidermis (K5.TGF beta 1 mice) show a psoriasiform phenotype, but the underlying pathogenic mechanisms are not entirely clear. To elucidate the contribution of T lymphocytes to the pathogenesis in K5.TGF beta 1 mice, we used three complementary approaches: first, peripheral T cells were eradicated via systemic treatment with CD3- or CD4-depleting antibodies. However, this elimination did not alleviate the chronic inflammatory disorder. Second, bone marrow transplantation from transgenic mice into wildtype recipients and vice versa resulted in the expected reconstitution of both adaptive and innate immune system but had little effect on the cutaneous phenotype both in wildtype and transgenic chimeras. Third, based on the hypothesis that the disease course could be modulated by regulatory T cells (Tregs), we expanded Tregs in vivo using a superagonistic anti-CD28 antibody. While this treatment achieved a threefold increase in Foxp3-expressing Tregs, there was little, if any, effect on the chronic skin inflammation. We conclude from our findings that T cells play little, if any, role in the skin lesions of K5.TGF beta 1 mice.

NF-kappaB inhibition through proteasome inhibition or IKKbeta blockade increases the susceptibility of melanoma cells to cytostatic treatment through distinct pathways.

Metastasized melanoma is almost universally resistant to chemotherapy. Given that constitutive or drug-induced upregulation of NF-kappaB activity is associated with this chemoresistance, NF-kappaB inhibition may increase the susceptibility to antitumoral therapy. On the cellular level, two principles of NF-kappaB inhibition, proteasome inhibition by bortezomib and IkappaB kinase-beta (IKKbeta) inhibition by the kinase inhibitor of NF-kappaB-1 (KINK-1), significantly increased the antitumoral efficacy of camptothecin. When combined with camptothecin, either of the two NF-kappaB-inhibiting principles synergistically influenced progression-related in vitro functions, including cell growth, apoptosis, and invasion through an artificial basement membrane. In addition, when C57BL/6 mice were intravenously injected with B16F10 melanoma cells, the combination of cytostatic treatment with either of the NF-kappaB-inhibiting compounds revealed significantly reduced pulmonary metastasis compared to either treatment alone. However, on the molecular level, nuclear translocation of p65, cell cycle analysis, and expression of NF-kappaB-dependent gene products disclosed distinctly different molecular mechanisms, resulting in the same functional effect. That proteasome inhibition and IKKbeta inhibition affect distinct molecular pathways downstream of NF-kappaB, both leading to increased chemosensitivity, is previously unreported. Thus, it is conceivable that switching the two principles of NF-kappaB inhibition, once resistance to one of the agents occurs, will improve future treatment regimens.

A critical comparison between two classical and a kit-based method for mitochondria isolation.

Numerous protocols for isolation of mitochondria are available. Here, three methods for the isolation of intact mitochondria from mouse liver tissues are compared with regard to yield, purity and activity. Mitochondria were isolated by sucrose density gradient ultracentrifugation, free-flow electrophoresis or a commercially available kit-based method. Our analyses show that the sophisticated (and most expensive) free-flow electrophoresis method enables isolation of intact mitochondria with an enrichment of approximately 70%. Using the classical density centrifugation method is very laborious and time-consuming, but delivers about 57% intact mitochondria. Using standard laboratory equipment in a quick and simple procedure, the kit provides approximately 50% intact mitochondria, suitable for most standard investigations.