In vivo effects of cytokines on psoriatic skin grafted on nude mice: involvement of the tumour necrosis factor (TNF) receptor

Tumor necrosis factor alpha-308 gene polymorphism and pseudoexfoliation glaucoma

PURPOSE

To investigate the possible association between tumor necrosis factor alpha (TNF-alpha)-308 G/A polymorphism and pseudoexfoliation (PEX) glaucoma.

METHODS

One hundred and ten Turkish PEX glaucoma patients and 110 healthy control subjects were enrolled in the study. All participants underwent a complete ophthalmic examination. TNF-alpha-308 was genotyped by polymerase chain reaction and restriction endonuclease analysis.

RESULTS

We found a high prevalence of the G/G genotype in PEX glaucoma patients (OR=2.88, 95% CI 1.15-7.20). The A polymorphic allele frequency was 3.2% in patients with PEX compared with 8.2% in controls (p=0.023).

CONCLUSIONS

Our results suggest that TNF-alpha-308 G/A genotype is not associated with PEX glaucoma. The -308G/A variant may be a possible protective factor against PEX.

TNF-α Gene Promoter -238G>A and -308G>A Polymorphisms Alter Risk of Psoriasis Vulgaris: A Meta-Analysis

Tumor necrosis factor-alpha (TNF-alpha) is a major proinflammatory cytokine and involved in the etiology of psoriasis. The -238G>A and -308G>A polymorphisms influence the transcription of the TNF-alpha gene and have been implicated in psoriasis risk. However, the results from the published studies on the association between TNF-alpha polymorphisms and psoriasis risk are conflicting. Our meta-analysis of a total of 997 psoriasis cases and 943 control subjects from eight published case-control studies for the -238G>A polymorphism and of 1,156 psoriasis cases and 1,083 control subjects from 10 published case-control studies for the -308G>A polymorphism showed that a significantly increased risk was associated with the variant GA+AA genotypes of -238G>A, compared with the GG genotype (odds ratio (OR) 2.60, 95% confidence interval (95% CI) 1.48-4.56), whereas a significantly reduced psoriasis risk was associated with the variant GA+AA genotypes of the -308G>A compared with the GG genotype (OR 0.57, 95% CI 0.45-0.71). Our findings suggest that TNF-alpha -238G>A and -308G>A polymorphisms might be used as biomarkers for psoriasis risk prediction. A single larger study with thousands of subjects and biochemical and biological characterization is warranted to evaluate further the role of -238G>A and -308G>A polymorphisms and psoriasis risk in a population of various ethnicities.

Current concepts in the immunopathogenesis of psoriasis

There is much evidence to support the concept that psoriasis is a type 1 autoimmune disease, primarily mediated by interferon gamma and other inflammatory cytokines. There has been renewed interest in the role of components of the innate immune system, however,and it may be that overlap between the innate and acquired arms of the immune system can better explain immunopathogenesis in psoriasis. Relevant cell types, receptors, and immune mediators within these traditional boundaries of the immune system are discussed.Finally, pathogenic contributions from important psoriatic mouse models and recent genomic data using the new gene chip technology are elaborated.

The treatment of psoriasis and psoriatic arthritis with etanercept: practical considerations on monotherapy, combination therapy, and safety

It is quite evident the pathogenesis of psoriasis is modulated by immune-mediated mechanisms that invoke activated T cells and inflammatory cytokines, such as tumor necrosis factor-alpha. Current immunosuppressive systemic treatments may be effective in controlling psoriasis to a certain degree but have significant drawbacks, such as toxicity and relapse of the disease on discontinuation. The advantages of biologic agents are their greater selectivity in targeting specific pathways in the inflammatory cascade of psoriasis with a much higher safety profile. With specific antagonism directed against tumor necrosis factor-alpha, etanercept has demonstrated remarkable efficacy in the treatment of psoriasis and psoriatic arthritis.

Treatment of severe recalcitrant plaque psoriasis with single-dose intravenous tumour necrosis factor-alpha antibody (infliximab)

Infliximab is a chimeric anti-tumour necrosis factor-alpha antibody that has been demonstrated to have marked efficacy in the treatment of psoriasis. Seven patients with chronic plaque psoriasis were treated with single-dose intravenous infliximab (5 mg/kg), and the Psoriasis Area and Severity Index (PASI) and Dermatology Life Questionnaire Index (DLQI) were used as a measure of treatment efficacy. There was an average improvement in PASI scores of 69% at 2 weeks post infusion. There was an improvement in DLQI of 61%. Four of the seven patients were also seen at 10 weeks post infusion and the improvement in PASI and DLQI was sustained. All patients tolerated the initial infusion well without adverse events. The results indicate that single-dose infliximab is an effective and efficacious therapy for recalcitrant psoriasis and has a prolonged therapeutic effect.

Cellular localization of fractalkine at sites of inflammation: antigen-presenting cells in psoriasis express high levels of fractalkine

BACKGROUND

Chemokines play a key role in cell trafficking at sites of inflammation. The fractalkine CX3C chemokine is unique in several aspects. Fractalkine is expressed on activated endothelial cells and exists in two forms, either membrane anchored or in a soluble form. The soluble form is a potent chemotactic agent for T cells/monocytes and the anchored form functions as an adhesion molecule. In view of these specific functions fractalkine is capable of controlling the key regulatory mechanisms of cell trafficking at sites of inflammation.

OBJECTIVES

Little is known about the significance of this important molecule in inflammatory diseases. We undertook this study to elucidate the role of fractalkine in inflammatory diseases of the skin.

METHODS

We used a polyclonal antifractalkine antibody (immunoperoxidase and immunofluorescence stainings) in cryosections obtained from tissues of normal skin and that of selected cutaneous inflammatory diseases (psoriasis, lichen planus, eczema).

RESULTS

Increased expression of fractalkine was observed in the dermal blood vessels of lichen planus, eczema and psoriasis tissues. The most striking finding was that the dermal dendrocytes in the papillary dermis of psoriasis tissues expressed high levels of fractalkine. Compared with 186.64 +/- 51.69 fractalkine positive dermal dendrocytes per mm2 of the upper dermis of psoriatic tissue, the number of positive cells in lichen planus, eczema, and normal skin were 17.29 +/- 12.50, 12.50 +/- 6.75 and 5.93 +/- 3.53, respectively. We also performed double label immunofluorescence staining with nerve growth factor receptor (NGF-R) antibody and fractalkine antibody. NGF-R-positive terminal cutaneous nerves were in close contact with the fractalkine-positive dermal dendrocytes in psoriatic lesions.

CONCLUSIONS

The results of this study confirm that fractalkine is upregulated at sites of inflammation. Thus, it is likely that this molecule plays a key part in cell trafficking. An increased expression of fractalkine at the dermal papillae provides a plausible explanation for the migration and accumulation of T cells at these sites in psoriasis. Earlier studies have reported an increased number of dermal dendrocytes in psoriatic tissue; however, the functional role of these cells in the pathogenesis of psoriasis is largely unknown. Expression of fractalkine on the surface of dermal dendrocytes suggests an active role for these cells in localization and activation of lesional T cells.

Inflammatory versus proliferative processes in epidermis. Tumor necrosis factor alpha induces K6b keratin synthesis through a transcriptional complex containing NFkappa B and C/EBPbeta

Epidermal keratinocytes respond to injury by becoming activated, i.e. hyperproliferative, migratory, and proinflammatory. These processes are regulated by growth factors and cytokines. One of the markers of activated keratinocytes is keratin K6. We used a novel organ culture system to show that tumor necrosis factor alpha (TNFalpha) induces the expression of K6 protein and mRNA in human skin. Multiple isoforms of K6 are encoded by distinct genes and have distinct patterns of expression. By having shown previously that proliferative signals, such as epidermal growth factor (EGF), induce expression of the cytoskeletal protein keratin K6b, we here demonstrate that the same isoform, K6b, is also induced by TNFalpha, a proinflammatory cytokine. Specifically, TNFalpha induces the transcription of the K6b gene promoter. By using co-transfection, specific inhibitors, and antisense oligonucleotides, we have identified NFkappaB and C/EBPbeta as the transcription factors that convey the TNFalpha signal. Both transcription factors are necessary for the induction of K6b by TNFalpha and act as a complex, although only C/EBPbeta binds the K6b promoter DNA. By using transfection, site-directed mutagenesis, and footprinting, we have mapped the site that responds to TNFalpha, NFkappaB, and C/EBPbeta. This site is separate from the one responsive to EGF and AP1. Our results show that the proinflammatory (TNFalpha) and the proliferative (EGF) signals in epidermis separately and independently regulate the expression of the same K6b keratin isoform. Thus, the cytoskeletal responses in epidermal cells can be precisely tuned by separate proliferative and inflammatory signals to fit the nature of the injuries that caused them.

Role of IL-6 in the Pleurisy and Lung Injury Caused by Carrageenan

In the present study we used IL-6 knockout mice (IL-6KO) to evaluate the role of IL-6 in the inflammatory response caused by injection of carrageenan into the pleural space. Compared with carrageenan-treated IL-6 wild-type (IL-6WT) mice, carrageenan-treated IL-6KO mice exhibited a reduced degree of pleural exudation and polymorphonuclear cell migration. Lung myeloperoxidase activity and lipid peroxidation were significantly reduced in IL-6KO mice compared with those in IL-6WT mice treated with carrageenan. Immunohistochemical analysis for nitrotyrosine and poly(A)DP-ribose polymerase revealed a positive staining in lungs from carrageenan-treated IL-6WT mice. No positive staining for nitrotyrosine or PARS was found in the lungs of the carrageenan-treated IL-6KO mice. Staining of lung tissue sections obtained from carrageenan-treated IL-6WT mice with an anti-cyclo-oxygenase-2 Ab showed a diffuse staining of the inflamed tissue. Furthermore, expression of inducible nitric oxide synthase was found mainly in the macrophages of the inflamed lungs from carrageenan-treated IL-6WT mice. The intensity and degree of the staining for cyclo-oxygenase-2 and inducible nitric oxide synthase were markedly reduced in tissue sections obtained from carrageenan-treated IL-6KO mice. Most notably, the degree of lung injury caused by carrageenan was also reduced in IL-6KO mice. Treatment of IL-6WT mice with anti-IL-6 (5 μg/day/mouse at 24 and 1 h before carrageenan treatment) also significantly attenuated all the above indicators of lung inflammation. Taken together, our results clearly demonstrate that IL-6KO mice are more resistant to the acute inflammation of the lung caused by carrageenan injection into the pleural space than the corresponding WT mice.

T-lymphocyte dependence of psoriatic pathology in human psoriatic skin grafted to SCID mice

Considerable indirect evidence suggests that T lymphocytes have a role in the pathogenesis of psoriasis. The goal of this study was to directly test the ability of T cells to maintain psoriasis pathology. Psoriatic skin was transplanted onto SCID mice, which were then injected with autologous T cells. T cells were cultured from either psoriatic skin lesions or peripheral blood and injected intradermally or intravenously. Control SCID mice transplanted with psoriasis grafts were not injected with T cells. After 10 wk, control psoriatic skin grafts not injected with T cells lost many of the features of psoriasis. Injection of peripheral blood T cells was not able to maintain these psoriatic features. In contrast, the injection of T cells derived from psoriatic skin was able to maintain the psoriatic phenotype. Psoriatic features that were maintained included epidermal thickness and labeling index and expression of HLA-DR, involucrin, and ICAM-1, as well as loss of expression of filaggrin. Injection of skin infiltrating T cells into skin of normal donors on SCID mice did not induce changes of psoriasis. The ability of T cells from lesional skin, but not peripheral blood, to maintain psoriasis suggests that psoriasis is mediated by an autoantigen reactive T cell, which is present at a higher frequency in the psoriatic lesion.