Tumor necrosis factor antagonists in the therapy of psoriasis

Animal models of psoriasis-highlights and drawbacks

Research into the pathophysiology of psoriasis remains challenging, because this disease does not occur naturally in laboratory animals. However, specific aspects of its complex immune-pathology can be illuminated through transgenic, knockout, xenotransplantation, immunological reconstitution, drug-induced, or spontaneous mutation models in rodents. Although some of these approaches have already been pursued for more than 5 decades and even more models have been described in recent times, they have surprisingly not yet been systematically validated. As a consequence, researchers regularly examine specific aspects that only partially reflect the complex overall picture of the human disease. Nonetheless, animal models are of great utility to investigate inflammatory mediators, the communication between cells of the innate and the adaptive immune systems, the role of resident cells as well as new therapies. Of note, various manipulations in experimental animals resulted in rather similar phenotypes. These were called "psoriasiform", "psoriasis-like" or even "psoriasis" usually on the basis of some similarities with the human disorder. Xenotransplantation of human skin onto immunocompromised animals can overcome this limitation only in part. In this review, we elucidate approaches for the generation of animal models of psoriasis and assess their strengths and limitations with a certain focus on more recently developed models.

Viewing Legionella pneumophila Pathogenesis through an Immunological Lens

Legionella pneumophila is the causative agent of the severe pneumonia Legionnaires' disease. L. pneumophila is ubiquitously found in freshwater environments, where it replicates within free-living protozoa. Aerosolization of contaminated water supplies allows the bacteria to be inhaled into the human lung, where L. pneumophila can be phagocytosed by alveolar macrophages and replicate intracellularly. The Dot/Icm type IV secretion system (T4SS) is one of the key virulence factors required for intracellular bacterial replication and subsequent disease. The Dot/Icm apparatus translocates more than 300 effector proteins into the host cell cytosol. These effectors interfere with a variety of cellular processes, thus enabling the bacterium to evade phagosome-lysosome fusion and establish an endoplasmic reticulum-derived Legionella-containing vacuole, which facilitates bacterial replication. In turn, the immune system has evolved numerous strategies to recognize intracellular bacteria such as L. pneumophila, leading to potent inflammatory responses that aid in eliminating infection. This review aims to provide an overview of L. pneumophila pathogenesis in the context of the host immune response.

FCGR3A-158 polymorphism influences the biological response to infliximab in Crohn's disease through affecting the ADCC activity

An association between FCGR3A-158 V/F polymorphism and biological responses to infliximab has been reported in Crohn's disease (CD) in Western countries. However, little is known about the mechanism by which gene polymorphism affects the responses to infliximab. The aims of this study were to confirm the association in Japanese CD patients and to reveal the effect of gene polymorphism on biological responses to infliximab. Japanese CD patients were examined retrospectively at weeks 8 and 30. Clinical and biological responses were assessed by the Crohn's disease activity index and C-reactive protein levels, respectively. The infliximab-binding affinity of natural killer (NK) cells from FCGR3A-158 V/V, V/F and F/F donors was examined. Infliximab-mediated antibody-dependent cell-mediated cytotoxicity (ADCC) activities were also determined using transmembrane TNF-α-expressing Jurkat T cells as target cells and peripheral blood mononuclear cells (PBMCs) from V/V, V/F and F/F donors as effector cells. Biological responses at week 8 were statistically higher in V/V patients, whereas no significant differences were observed in either clinical responses at weeks 8 and 30 or biological responses at week 30 among the three genotypes. NK cells and PBMCs from V/V patients also showed higher infliximab-binding affinity and infliximab-mediated ADCC activity, respectively. Our results suggest that FCGR3A-158 polymorphism is a predicting factor of biological responses to infliximab in the early phases. FCGR3A-158 polymorphism was also found to affect the infliximab-binding affinity of NK cells and infliximab-mediated ADCC activity in vitro, suggesting that an effect on ADCC activity influences biological responses to infliximab in CD patients.

Role of NF-κB in epithelial biology

Since its discovery, nuclear factor-κB (NF-κB) has been recognized as a critical regulator of immune responses. While early studies focused on studying the role of NF-κB in the development and function of immune cells, more recently the function of the inhibitor of NF-κB kinase (IKK)/NF-κB pathway in non-immune cells has gained increased attention. Studies in genetic mouse models were instrumental in dissecting the cell-specific functions of NF-κB and provided experimental evidence that NF-κB signaling in epithelial cells is important for the maintenance of immune homeostasis in barrier tissues such as the skin and the intestine. Increased activation of IKK/NF-κB triggered cytokine expression by the epithelial cells, resulting in exacerbated tissue inflammatory responses. NF-κB inhibition in keratinocytes triggered severe tumor necrosis factor-dependent skin inflammation and epidermal hyperplasia, while inhibition of IKK/NF-κB signaling in intestinal epithelial cells disturbed the intestinal barrier and triggered severe chronic colon inflammation. Therefore, epithelial NF-κB signaling performs critical 'peace keeping' functions in barrier tissues at the interface with the environment by regulating cell survival, barrier integrity, and the immunological and anti-microbial responses of epithelial cells. Improved understanding of epithelial NF-κB functions may hold the key for elucidating the etiology and pathophysiology of chronic inflammatory diseases in epithelial tissues.

Psoriasis, hepatitis B, and the tumor necrosis factor-alpha inhibitory agents: a review and recommendations for management

BACKGROUND

Tumor necrosis factor inhibitory agents are currently considered to be contraindicated in psoriatic patients with hepatitis B.

OBJECTIVE

We aim to provide guidance to dermatologists on the use of tumor necrosis factor inhibitor therapy in these patients.

METHODS

The current literature was reviewed regarding the use of tumor necrosis factor-alpha inhibitory agents (etanercept, adalimumab, and infliximab) in psoriatic patients with particular reference to hepatitis B infection.

RESULTS

Tumor necrosis factor-alpha inhibitor therapy may result in reactivated hepatitis B in hepatitis B surface antigen-positive patients with psoriasis. This also occurs, although less frequently in patients with an isolated positive hepatitis B core antibody. Thus, all psoriasis patients should be screened for hepatitis B surface antigen plus hepatitis B core antibody prior to the initiation of tumor necrosis factor-alpha inhibitor therapy. Infliximab has been associated with more reactivation cases than the other 2 agents and fatalities have been reported with this agent. Evidence is presented that the risk of reactivation can be greatly minimized or eliminated by early or pre-emptive antiviral therapy.

LIMITATIONS

The data is largely based on small case series that are retrospective in nature.

CONCLUSIONS

Hepatitis B screening is essential prior to the initiation of tumor necrosis factor-alpha inhibitor therapy. Psoriatic patients found to be hepatitis B surface antigen or hepatitis B core antibody-positive should be referred to an appropriate specialist for evaluation and therapy. This would allow for the safe use of tumor necrosis factor-alpha inhibitors in psoriatic patients despite recently published guidelines to the contrary.

Chiral flavanones from Amygdalus lycioides Spach: structural elucidation and identification of TNFalpha inhibitors by bioactivity-guided fractionation

Phytochemical investigation on the Amygdalus lycioides Spach branchelets resulted in the isolation of four chiral flavanones: (2R,3R)-Taxifolin, (2R,3R)-aromadendrin, (S)-5,7,3',5'-tetrahydroxyflavanone and (S)-naringenin. The flavanones were isolated by semi-preparative HPLC, their structures elucidated based on spectroscopic data and their absolute configuration assigned. As a part of our ethnobotanical-directed search for novel TNFα inhibitors, the bioassay-guided fractionation of the n-hexane-acetone (n-Hex-Ac, 1:1 v/v) Amygdalus lycioides Spach branchelets extract was performed. In this way, (S)-naringenin was identified as the constituent responsible for the TNFα blocking effect, being effective in vitro and in vivo after oral administration. This is the first investigation on bioactive secondary metabolites of Amygdalus lycioides Spach branchelets.

Black hairy tongue associated with erlotinib treatment in a patient with advanced lung cancer

Erlotinib is a tyrosine kinase inhibitor that acts on the epidermal growth factor receptor (EGFR). There have been many reports of the mucocutaneous side effects related to several EGFR inhibitors (EGFRIs). However, no case of black hairy tongue (BHT) associated with EGFRI has been reported. Herein, we report the first case of erlotinib-induced BHT in a 61-year-old man with advanced lung cancer. Considering recent use of EGFRIs worldwide, dermatologists should recognize the possible occurrence of BHT associated with EGFRIs such as erlotinib.

The adaptor protein FADD protects epidermal keratinocytes from necroptosis in vivo and prevents skin inflammation

Epidermal keratinocytes provide an essential structural and immunological barrier forming the first line of defense against potentially pathogenic microorganisms. Mechanisms regulating barrier integrity and innate immune responses in the epidermis are important for the maintenance of skin immune homeostasis and the pathogenesis of inflammatory skin diseases. Here, we show that epidermal keratinocyte-restricted deficiency of the adaptor protein FADD (FADD(E-KO)) induced severe inflammatory skin lesions in mice. The development of skin inflammation in FADD(E-KO) mice was triggered by RIP kinase 3 (RIP3)-mediated programmed necrosis (termed necroptosis) of FADD-deficient keratinocytes, which was partly dependent on the deubiquitinating enzyme CYLD and tumor necrosis factor (TNF)-TNF receptor 1 signaling. Collectively, our findings provide an in vivo experimental paradigm that regulation of necroptosis in keratinocytes is important for the maintenance of immune homeostasis and the prevention of chronic inflammation in the skin.

Adipokines and psoriasis

Adipose tissue is an active endocrine organ contributing to the regulation of multiple metabolic pathways via self-produced bioactive products called adipokines. These adipokines are key players in the pathogenesis of metabolic syndrome and cardiovascular diseases. Co-occurrence of obesity and psoriasis could lead to interactions of both diseases in which adipokines, at least in part, are involved and may contribute to associated comorbidities of psoriasis. Until today numerous adipokines have been identified of which the most important ones are discussed in the following within the context of obesity, chronic inflammation and their possible role in the pathogenesis of psoriasis. Adipokines could serve as a missing link in the causal relationship between psoriasis and comorbidities and may provide a biomarker for disease severity, risk of comorbidities and treatment success.

Upregulation and nuclear localization of TNF-like cytokine 1A (TL1A) and its receptors DR3 and DcR3 in psoriatic skin lesions

TNF is critically involved in the pathogenesis of psoriasis. TL1A is a TNF-like cytokine, which, after binding to death domain receptor DR3, provides costimulatory signals to lymphocytes, amplifies Th1- and Th17-mediated immune responses and induces apoptotic cell death. These functions are inhibited when TL1A associates to decoy receptor DcR3. In the present study, we investigated the expression profiles for TL1A, DR3 and DcR3 in the normal skin and in psoriatic skin lesions. By use of immunohistochemistry, we were able to demonstrate constitutive cutaneous expression of DR3 and DcR3 but not of TL1A in healthy skin. On the other hand, in patients with active psoriasis, we observed abundant immunostaining for TL1A and significant upregulation of its receptors (P < 0.05 in comparison to healthy skin). TL1A, DR3 and DcR3 proteins, as well as mRNA transcripts reflecting in situ production of TL1A and DcR3, were also specifically increased in lesional as compared to non-lesional skin from patients with psoriasis (P < 0.05). These proteins were upregulated in cell populations that are critically involved in the pathogenesis of chronic skin inflammation, such as keratinocytes, macrophages in deep dermis and cells at the perivascular/endothelial area. Finally, we provide evidence for the existence of nuclear localization of TL1A in inflammatory cells from psoriatic lesions. This was also observed in inflamed synovia from patients with rheumatoid arthritis, but not in neoplastic TL1A-expressing cell lines. We conclude that interactions between TL1A and its two receptors may be involved in the pathogenesis of chronic skin inflammation that takes place in psoriasis.

Up-regulation of TNF-alpha secretion by cigarette smoke is mediated by Egr-1 in HaCaT human keratinocytes

Many epidemiologic studies have pointed to a significant association between cigarette smoking and inflammatory skin disease such as psoriasis. Cigarette smoke induces expression of regulators of inflammation such as interleukin (IL)-1, IL-6, IL-8 and tumor necrosis factor (TNF)-alpha. It was recently demonstrated that early growth response-1 (Egr-1) transcription factor is significantly up-regulated in the skin lesions of patients with psoriasis. The mechanism by which cigarette smoke extract (CSE) regulates inflammatory cytokine expression in keratinocyte was still unknown. The aim of this study was to investigate the signalling of CSE-induced Egr-1 expression and the role for Egr-1 in CSE-induced TNF-alpha expression. Cytotoxicity of CSE in HaCaT cells was measured by thiazolyl blue tetrazolium bromide (MTT) assay. CSE-induced Egr-1 expression was investigated by western blot, luciferase reporter assay and confocal microscopy. TNF-alpha expression was measured by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. Involvement of Egr-1 in CSE-induced TNF-alpha secretion was determined by using Egr-1 specific siRNA. CSE increases the Egr-1 expression, promoter activity and its nuclear translocation in human HaCaT keratinocytes. CSE activates mitogen-activated protein kinase (MAPK) pathways including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). Up-regulation of Egr-1 expression by CSE stimulation was found to be inhibited by an ERK and JNK but not p38 inhibitor. CSE increases TNF-alpha expression and secretion. This increase is mediated by CSE-induced Egr-1 expression. Our results showed that CSE induces Egr-1 expression via MAPK pathway in human keratinocytes and TNF-alpha expression by Egr-1. This pathway may contribute to the development of inflammatory disease such as psoriasis.

[Treatment of psoriasis using biologics]

Psoriasis is a chronic inflammatory skin disease, which is characterized by red, scaly, raised plaques. Its symptoms may range in severity and there are severe clinical subtypes of psoriasis including pustular psoriasis. Pre-biological systemic therapies were targeting mainly keratinocyte proliferation and T cell activation. However, there were cases, in which these classic therapies were not fully effective or could not be used because of the accompanied severe organ failure of the psoriasis patient. Recent progress in psoriasis research has clarified which of the cells, cell surface molecules and cytokines play a pivotal role in the pathogenesis of psoriasis. Biological systemic therapies targeting these molecules have turned out to be extremely effective in treating psoriasis and are now used to treat moderate to severe psoriasis worldwide. These biological therapies are not only more effective than pre-biological systemic therapies, but also show more rapid response, and long-term efficacy is expected. The TNF-alpha inhibitors are now approved as the first biological therapy for psoriasis in Japan. These TNF-alpha inhibitors are expected to be a new standard therapy for severe psoriasis, however, since the long-term safety is an unsolved issue, careful clinical monitoring is required. (193 words).

Current status and new developments in the treatment of psoriasis and psoriatic arthritis with biological agents

Psoriasis is a chronic inflammatory disease affecting 1-3% of the general population. Among psoriatic patients, 5-40% are affected by psoriatic arthritis. Due to the chronic nature of the disease, patients suffer from substantial psychological and financial burdens, thus adding to a significantly impaired quality of life. Traditional systemic therapies for psoriasis, such as methotrexate, cyclosporin A, retinoids or PUVA therapy, have a potential for long-term toxicity and may not always provide sufficient improvement of the disease. The development of novel therapies targeting key steps in the pathogenesis of psoriasis and psoriatic arthritis now provide new and efficient treatment options. Biological therapies for the treatment of psoriasis and/or psoriatic arthritis are defined by their mode of action and can be classified into three categories: the T-cell modulating agents (alefacept and efalizumab), the inhibitors of tumour necrosis factor-alpha (TNFalpha blockers, e.g. adalimumab, certolizumab, etanercept, golimumab and infliximab) and the inhibitors of interleukin (IL) 12 and IL-23 (e.g. ustekinumab and briakinumab). This article provides a brief overview of the currently approved biological agents in the European Union and of some newer agents, such as briakinumab, certolizumab and golimumab.

Safety and efficacy of the tumor necrosis factor antagonists

Psoriasis is one of the most common systemic inflammatory diseases and affects the quality of life of the affected persons profoundly. Further knowledge of the pathogenesis and new biotechnological techniques have made it possible to develop new targeted therapies, such as antibodies against tumor necrosis factor (TNF)-alpha. Today, 3 TNF inhibitors, infliximab, adalimumab, and Etanercept, have been approved for the treatment of psoriasis arthritis, psoriasis, and other indications like Crohn's disease, depending on the distinct substance by the European Medicines Agency. Golimumab was approved in September 2009 for the use in psoriasis arthritis, respectively. These substances have added new effective treatment options to the therapeutic armamentarium of psoriasis. To use these new treatments for the best of our patients, it is important to know the correct application, the advantages, as well as contraindications or possible adverse effects of the substances. This article provides an update on the TNF-alpha inhibitors with emphasis on practical daily use. Most data are on the basis of high-quality studies and official guidelines, but if necessary, data from recent publications or clinical expertise have been added. In summary, with TNF inhibitors we have gained effective new treatment options showing a favorable safety profile when paying attention to safety aspects before and during therapy (screening, monitoring).

Radiation-induced bystander signaling pathways in human fibroblasts: a role for interleukin-33 in the signal transmission

The main goal of this study is to elucidate the mechanisms of the signal transmission for radiation-induced bystander response. The NF-kappaB-dependent gene expression of IL8, IL6, PTGS2/COX2, TNF and IL33 in directly irradiated human skin fibroblasts produced the cytokines and prostaglandin E2 (PGE2) with autocrine/paracrine functions, which further activated signaling pathways and induced NF-kappaB-dependent gene expression in bystander cells. As a result, bystander cells also started expression and production of interleukin-8, interleukin-6, COX-2-generated PGE2 and interleukin-33 (IL-33) followed by autocrine/paracrine stimulation of the NF-kappaB and MAPK pathways. A blockage of IL-33 transmitting functions with anti-IL-33 monoclonal antibody added into the culture media decreased NF-kappaB activation in directly irradiated and bystander cells. On the other hand, the IGF-1-Receptor kinase regulated the PI3K-AKT pathway in both directly irradiated and bystander fibroblasts. A pronounced and prolonged increase in AKT activity after irradiation was a characteristic feature of bystander cells. AKT positively regulated IL-33 protein expression levels. Suppression of the IGF-R1-AKT-IL-33 pathway substantially increased radiation-induced or TRAIL-induced apoptosis in fibroblasts. Taken together, our results demonstrated the early activation of NF-kappaB-dependent gene expression first in directly irradiated and then bystander fibroblasts, the further modulation of critical proteins, including IL-33, by AKT in bystander cells and late drastic changes in cell survival and in enhanced sensitivity to TRAIL-induced apoptosis after suppression of the IGF-1R-AKT-IL-33 signaling cascade in both directly irradiated and bystander cells.

Psoriasis: targeting therapy towards the inflammatory cascade

Psoriasis is a chronic inflammatory disease of the skin and joints that typically follows a relapsing/remitting disease course. Whereas psoriasis is primarily a T-cell-mediated disease, intrinsic alterations in epidermal keratinocytes also play an important role. Tumor necrosis factor alpha (TNFalpha) has been identified as an important cytokine in the inflammatory cascade of psoriasis. The importance of TNFalpha is further underlined by the therapeutic efficacy of compounds that interfere with TNFalpha function, such as biological agents.

Progress in epidermolysis bullosa research: toward treatment and cure

Epidermolysis bullosa (EB) is a clinically and genetically heterogeneous group of blistering disorders with considerable morbidity and mortality. Two decades ago, EB entered the molecular era with the identification of mutations in specific genes expressed within the cutaneous basement membrane zone; mutations in 14 genes have now been identified. This progress has now formed the basis for development of novel molecular therapies for this disease.

Regulation of tissue homeostasis by NF-kappaB signalling: implications for inflammatory diseases

The nuclear factor-kappaB (NF-kappaB) signalling pathway regulates immune responses and is implicated in the pathogenesis of many inflammatory diseases. Given the well established pro-inflammatory functions of NF-kappaB, inhibition of this pathway would be expected to have anti-inflammatory effects. However, recent studies in mouse models have led to surprising and provocative results, as NF-kappaB inhibition in epithelial cells resulted in the spontaneous development of severe chronic inflammatory conditions. These findings indicate that NF-kappaB signalling acts in non-immune cells to control the maintenance of tissue immune homeostasis. This Review discusses the mechanisms by which NF-kappaB activity in non-immune cells regulates tissue immune homeostasis and prevents the pathogenesis of inflammatory diseases.

Biologics in the management of psoriasis

Psoriasis is a chronic inflammatory systemic disease for which there exist topical, ultraviolet, systemic, and biologic treatments. Biologic agents selectively interfere with the immune mechanisms responsible for psoriasis. Etanercept, infliximab, and adalimumab target tumor necrosis factor-alpha and have demonstrated efficacy in the treatment of psoriasis and psoriatic arthritis. Alefacept and efalizumab target T lymphocytes, are effective in the treatment of psoriasis, but are not approved for psoriatic arthritis. Finally, ustekinumab and ABT-874 target interleukin-12 and interleukin-23, and they have demonstrated efficacy in the treatment of psoriasis. The objective of this review is to present efficacy and safety data from randomized controlled trials of the biologic agents in the treatment of psoriasis.

Targeted treatment of psoriasis with adalimumab: a critical appraisal based on a systematic review of the literature

Psoriasis is a chronic inflammatory disease affecting 2% to 3% of the population in Western countries. Psoriasis is associated with limited quality of life, cardiovascular disease, and depression. The approval of injectable biological agents has revolutionized the management of moderate to severe psoriasis. Adalimumab is a human monoclonal antibody against tumor necrosis factor (TNF) alpha approved for moderate-to-severe plaque-type psoriasis and psoriatic arthritis (PsA). This systematic review summarizes the evidence concerning the efficacy, clinical effectiveness, safety, and cost-effectiveness of adalimumab in the treatment of psoriasis. Five randomized controlled trials demonstrated the efficacy of adalimumab in moderate-to-severe plaque-type psoriasis and PsA with PASI-75 response rates of 53% to 80% and ACR-20 response rates of 39% to 58% after 12 to 16 weeks of treatment. In clinical practice patients who have not responded to one TNF antagonist may respond to another TNF antagonist. Adalimumab has similar or better cost-effectiveness than other biologics, but is less efficient than methotrexate and cyclosporine. Adalimumab is generally well tolerated. Patients should be evaluated for active/latent tuberculosis, serious infections, and other contraindications prior to initiation of adalimumab therapy. Future studies should investigate the comparative efficacy of adalimumab and other biologic and prebiologic agents. Recently established registries will yield additional data on the effectiveness and long-term safety of adalimumab.

Unraveling the genetics of complex diseases: susceptibility genes for rheumatoid arthritis and psoriasis

Talk of numerous genetic risk factors for rheumatoid arthritis (RA) and psoriasis has been percolating for years, but with the exception of the human leukocyte antigen (HLA) region, none have been definitively identified. Recently the results of multiple, well powered, genetic case-control studies have begun to appear providing convincing statistical evidence for at least ten non-HLA related risk genes or loci (C5/TRAF1, CD40, CTLA4, KIF5A/PIP4K2C, MMEL1/TNFRSF14, PADI4, PRKCQ, PTPN22, STAT4, and TNFAIP3/OLIG3) for RA and six (IL12B, IL13, IL23R, STAT2/IL23A, TNFAIP3, and TNIP1) for psoriasis. These initial, novel findings are beginning to shed light on the molecular pathways pertinent to the individual diseases and highlight the pleiotropic effects of several risk factors as well as the allelic heterogeneity underlying susceptibility to these and other autoimmune diseases.

Infliximab in the treatment of plaque type psoriasis

Psoriasis is a chronic and immunomediated skin disease characterized by erythematous scaly plaques. Psoriasis affects approximately 1% to 3% of the Caucasian population. Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine that plays a critical role in the pathogenesis of psoriasis. Infliximab is an anti-TNF-α drug widely used for the treatment of plaque type psoriasis and psoriatic arthritis. Controlled clinical trials demonstrated that infliximab is characterized by a high degree of clinical response in moderate to severe plaque psoriasis. Moreover infliximab showed rapid efficacy in nail psoriasis which represents a therapeutic challenge for dermatologists and a relevant source of distress for patients with plaque psoriasis. This anti-TNF-α has an encouraging safety profile, especially as long as physicians are watchful in prevention and early diagnosis of infections and infuse reactions. The efficacy, tolerability and safety profiles suggest infliximab as a suitable anti-psoriatic drug in the long-term treatment of a chronic disease such as plaque-type psoriasis.