Expression and modulation of LL-37 in normal human keratinocytes, HaCaT cells, and inflammatory skin diseases

Defensins and cathelicidins (LL-37) are major antimicrobial peptides (AMPs) of the innate immune system of the human skin. In normal non-inflamed skin these peptides are negligible, but their expression can be markedly increased in inflammatory skin disease such as psoriasis. We designed this study to identify the expressions of LL-37 in normal human keratinocyte (NHK) and HaCaT cells after exposure to stimulants and to investigate difference of LL-37 expression accompanied with cell differentiation status, and come to understand difference of susceptibility to infection in atopic dermatitis and psoriasis. Expressions of LL-37 in NHKs and HaCaT cells were evaluated by using RT-PCR, Western blotting, and immunohistochemical (IHC) staining at 6, 12, and 24 hr post stimulation after exposure to Ultraviolet B irradiation and lipopolysaccharide. And expression of LL-37 in skin biopsy specimens from patients with atopic dermatitis and psoriasis was determined by immunohistochemical analysis. In time-sequential analyses of LL-37 expression revealed that LL-37 was expressed in NHKs, but not in HaCaT cells. IHC analysis confirmed the presence of abundant LL-37 in the epidermis of psoriasis. Therefore we deduced that expression of LL-37 is affected by UV irradiation, bacterial infection, and status of cell differentiation.     

A Review on the Potential Role of Basement Membrane Laminin in the Pathogenesis of Psoriasis

We have previously reviewed alterations to basement membrane laminin in psoriasis and how disruption of this layer could lead to at least some of the pathological changes observed. We here postulate that basement membrane laminin is the key antigen in driving psoriasis, inducing a T cell‐mediated autoimmune response. For laminin to be considered as the key autoantigen in psoriasis, it would be reasonable to expect the following to be demonstrable: (1) that autoantigens are present in psoriatic inflammation; (2) that basement membrane laminin is perturbed in involved and uninvolved skin, and that some of the pathological changes associated with psoriasis could be predicted as a sequel to this; (3) that disruption of the basement membrane is among the earliest events in the evolution of psoriatic lesions; (4) that as streptococcal pharyngitis is the most clearly defined event to trigger or exacerbate psoriasis, then a T cell‐mediated autoimmune response to laminin should be anticipated as a potential sequelae to streptococcal pharyngitis; (5) that T cells in psoriasis can be shown to react to peptides with homology to laminin; (6) that HLACw6, as the most closely related gene associated with psoriasis and which is involved in antigen expression, should be preferentially expressed within lesional psoriasis towards the basement membrane, together with other proximal associated immune activity; and (7) that there is some association between antilaminin pemphigoid, a humorally mediated autoimmune disease to skin basement membrane laminin, and psoriasis. We here review the data relevant to each of these requirements.     

Differential major histocompatibility complex class I chain-related A allele associations with skin and joint manifestations of psoriatic disease

About 30% of patients with psoriasis have psoriatic arthritis (PsA), an inflammatory arthritis that can affect both axial and peripheral joints. Major histocompatibility complex class I chain-related A (MICA) alleles have previously been shown to be associated with PsA; however it is unclear whether there is a differential association of MICA alleles with skin and joint manifestations of PsA. Here, we describe a case-control study that aims to validate previously reported MICA allele associations with PsA and determine whether MICA alleles differentiate patients with PsA from those with psoriasis without PsA. Two hundred forty-nine unrelated Caucasian PsA patients, 243 psoriasis patients without arthritis, and 248 healthy controls were genotyped for 55 MICA alleles using PCR-SSP, and for human leucocyte antigen (HLA)-B and HLA-C alleles by PCR-SSO reverse line blot. Allele frequencies were calculated and logistic regressions were performed, adjusting for HLA-B and HLA-C alleles previously shown to be associated with psoriasis and/or PsA. Several MICA alleles were associated with psoriatic disease, PsA, and psoriasis compared with controls, and PsA compared with psoriasis in univariate analyses. Haplotype analysis showed evidence of strong linkage disequilibrium (LD) between PsA and psoriasis risk alleles of HLA-C, HLA-B, and MICA. After adjusting for significant HLA-B and HLA-C alleles in multivariate analyses, MICA*016 remained significantly associated with psoriasis [odds ratio (OR) = 5.5, P = 0.008]. MICA*00801 homozygosity was associated with susceptibility to PsA when compared with patients with psoriasis alone (OR = 2.26, P = 0.009). We conclude that most MICA allele associations with psoriasis and PsA are dependent on LD with HLA-B and HLA-C risk alleles. Independent of HLA, only MICA*016 influences the risk of developing psoriasis without arthritis, and homozygosity for MICA*00801 increases the risk of developing PsA in patients with psoriasis.     

A Cutting Edge Overview: Psoriatic Disease

Psoriasis is a lifelong skin disease, affecting about 2% of the global population. Generalized involvement of the body (erythroderma), extensive pustular lesions, and an associated arthritis known as psoriatic arthritis (PsA) are severe complications of psoriasis. Genetic, immunologic, and environmental factors contribute to its pathogenesis. A complete understanding of the pathogenesis of psoriasis and psoriatic arthritis is lacking. Cytokines, chemokines, adhesion molecules, growth factors like NGF, neuropeptides, and T cell receptors all act in an integrated way to evolve into unique inflammatory and proliferative processes typical of psoriasis and PsA. Management of psoriasis requires exemplary skin care along with careful monitoring of arrays of comorbidities which includes arthritis and coronary artery disease. In many ways, psoriasis can be considered a model autoimmune disease. This statement itself is ironic considering that it was not recognized as immune mediated until relatively recently. Fortunately, the immunobiology has made enormous strides and there are now excellent therapeutic options for patients. In this thematic review, we have attempted to provide summaries of not only basic science and clinical research, but also an overview of future research directions.     

TNFα Inhibitors in the Treatment of Psoriasis and Psoriatic Arthritis

Psoriasis is a chronic inflammatory skin disease that can lead to significant physical and psychologic distress for patients. Psoriatic arthritis (PsA), originally thought to be quite a mild disorder, is now recognized as a progressive and destructive arthritis. To date, therapies for both these conditions have been non-specific and unable to maintain long-lasting remission. In addition, many of the current therapies have significant adverse effects, limiting their usefulness. However, elucidation of the pathogenesis of psoriasis and PsA at a molecular level and the development of selective biologic agents have led to an enormous expansion of the armamentarium available to psoriasis patients. Two agents (infliximab and etanercept) selectively block the role of the cytokine tumor necrosis factor (TNF)-alpha and have proved effective in clinical trials in the treatment of both the skin and the joint manifestations of psoriasis. A third anti-TNF alpha agent (adalimumab Humira) is licensed for the treatment of rheumatoid arthritis; however, no studies have been published to date on its use in PsA or psoriasis. It is known that TNF alpha is elevated in both the skin and synovium of psoriatic patients and the effectiveness of its blockade by these two agents in psoriasis and PsA confirms its role in their pathogenesis. Randomized, double-blind, placebo-controlled trials have been performed with both agents in the treatment of psoriasis and PsA; in the case of etanercept these have been to support US FDA approval for use in psoriatic arthropathy. These studies are supported by smaller cohorts in open-label studies and anecdotal reports in the literature. Anti-TNF alpha therapy has proved to have disease-reducing activity in PsA and psoriasis and appears to be well tolerated. These studies have generally featured small numbers of patients and, until a larger cohort of treated patients is available, vigilance must be exercised. A considerable body of post-marketing safety data exists on the use of infliximab in rheumatoid arthritis and Crohn disease and for etanercept in rheumatoid arthritis and PsA. Certain issues, particularly the risk of infection, have emerged as features of the use of these agents. It remains to be seen whether effects seen in other disease entities may be extrapolated to psoriatic patients. More long-term data and experience are needed to define the role of anti-TNF alpha agents in the management of psoriasis and PsA. In particular, more studies are required to elucidate the finer points of co-medication; in some studies both agents have been used with other medications but there have been no formal trials of various possible combinations.     

Role of IL-17 in Psoriasis and Psoriatic Arthritis

The role of T cell subpopulations in human disease is in a transition phase due to continuous discovery of new subsets of T cell, one of which is Th17, characterized by the production of signature cytokine IL-17. In the last couple of years, many articles are coming out on the role of Th17 and its signature cytokine IL-17 in different autoimmune diseases like rheumatoid arthritis, psoriasis, psoriatic arthritis (PsA), SLE and multiple sclerosis. Psoriasis and PsA are immune-mediated diseases, affecting the skin and joints, respectively. Initially, it was thought that psoriasis and PsA were Th1-mediated diseases; however, studies in knockout animal models (IL-17 knockout mice) as well as human experimental data indicate that Th17 and its signature cytokine IL-17 have a critical role in the pathogenesis of psoriatic disease. Th17 cells have been identified from the dermal extracts of psoriatic lesions. Subsequently, our research group has substantiated this observation that Th17 cells are enriched in the papillary dermis of psoriatic plaques and in freshly isolated effector T lymphocytes from the synovial fluid of PsA patients, and we have reported that the majority of these CD4?+?IL-17+ T cells are of memory phenotype (CD4RO⁺CD45RA^?CD11a⁺). Recent reports also suggest that the synovial tissue in psoriatic arthritis is enriched with IL-17R, and its most well recognized receptor IL-17RA is functionally active in psoriatic arthritis. In this review article, we have discussed the role of IL-17 in psoriatic disease and have narrated about the novel IL17/IL-17R antibodies currently in preparation for its therapeutic uses in autoimmune diseases.     

The role of T cells in cutaneous autoimmune disease

T cells assume a fundamental function in immunosurveillance and maintenance of the cutaneous immune barrier, yet derangement of their requisite role effects a range of cutaneous autoimmune diseases with significant associated morbidity. While blistering skin diseases, such as pemphigus vulgaris (PV), pemphigus foliaceus (PF) and bullous pemphigoid (BP) are mediated by antibodies directed against autoantigens found in the skin, recent evidence has shown that T cell activation is crucial for the initiation and coordination of this humoral response. Non-blistering skin diseases, such as alopecia areata (AA), vitiligo (VL) and psoriasis (PS) are increasingly believed to be directly mediated by the activities of autoreactive T cells. Here, we examine T lymphocyte control of antibody-mediated and cell-mediated processes involved in the pathoimmunology of the above mentioned skin diseases.     

The role of T cells in cutaneous autoimmune disease

T cells assume a fundamental function in immunosurveillance and maintenance of the cutaneous immune barrier, yet derangement of their requisite role effects a range of cutaneous autoimmune diseases with significant associated morbidity. While blistering skin diseases, such as pemphigus vulgaris (PV), pemphigus foliaceus (PF) and bullous pemphigoid (BP) are mediated by antibodies directed against autoantigens found in the skin, recent evidence has shown that T cell activation is crucial for the initiation and coordination of this humoral response. Non-blistering skin diseases, such as alopecia areata (AA), vitiligo (VL) and psoriasis (PS) are increasingly believed to be directly mediated by the activities of autoreactive T cells. Here, we examine T lymphocyte control of antibody-mediated and cell-mediated processes involved in the pathoimmunology of the above mentioned skin diseases.     

Leflunomide in psoriatic arthritis

Psoriatic arthritis (PsA) is a common unique form of inflammatory arthritis associated with psoriasis. Its exact prevalence is unknown but 5-30% of the 2-3% of subjects of the general population affected with psoriasis are developing PsA. Typically PsA presents as an oligoarticular asymmetrical arthritis with predominant distal finger joint pattern, presence of spinal involvement enthesitis and dactylitis. There is evidence that T-cells play a key role in the immunopathology of PsA as well as Psoriasis. Leflunomide, a selective pyrimidine synthesis inhibitor with the property to inhibit T-cell activation and proliferation has been shown to improve both joint and skin symptoms in patients with PsA. Significant response rates have been observed for Psoriatic Arthritis Response Criteria (PsARC), modified ACR20 and PASI 50 after 24 weeks of treatment with 20 mg/d Leflunomide orally in a randomised, placebo controlled multicenter trial (TOPAS Study). Leflunomide treatment also improved quality of life and showed a favourable safety profile. It is therefore concluded that Leflunomide offers an efficacious, well tolerated, safe, and relatively inexpensive therapeutic option for the treatment of actively inflamed joints and psoriatic skin lesions in patients with PsA.     

Amplifying the concept of psoriatic arthritis: The role of autoimmunity in systemic psoriatic disease

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis that may be present in near 30% of patients affected by psoriasis (PsO), clinically characterized by inflammation of periarticular (e.g., enthesis) and articular structures. Recently, an autoimmune footprint of PsA pathogenesis has been demonstrated with the presence of autoantigens and related autoantibodies in PsA patients' sera. In this context, histological features of PsA synovitis supports the relevance of an autoimmune pathogenesis of the disease. Since there is no currently validated test for PsA, the analysis of PsA synovial tissue revealed pathognomonic characteristics of PsA that may support the clinician in the clinical practice. PsA synovitis is characterized by a sublining infiltrate with T and B cells, vascular proliferation and a relative thin lining layer of proliferating intimal synoviocytes. PsA synovial histopathology shows that ectopic lymphoid-neogenesis with an increase of IL-23 expression. These new pathogenetics features and the systemic nature of the disease raised the concept of a Systemic Psoriatic Disease (SysPsD), characterized by multiple extra-cutaneous and –articular manifestations, highlightening the great heterogeneity of this condition. SyPsD represents a heterogeneous chronic inflammatory condition with a wide spectrum of phenotypical manifestations. The purpose of this review is to describe the new pathogenetic mechanisms and the different clinical pictures of SysPsD, with the ultimate goal of improving the knowledge of this heterogeneous chronic inflammatory condition.     

Cytokine milieu of atopic dermatitis skin subverts the innate immune response to vaccinia virus

Atopic dermatitis (AD) is associated with eczema vaccinatum (EV), a disseminated viral skin infection that follows inoculation with vaccinia virus (VV). This study examined whether AD skin can control VV replication, and the role of IL-4 and IL-13 in modulating the human cathelicidin LL-37, an antimicrobial peptide that kills VV. AD skin exhibited increased VV replication and decreased LL-37 expression compared to normal or psoriasis skin. IL-4/IL-13 enhanced VV replication while downregulating LL-37 in VV-stimulated keratinocytes. Neutralizing IL-4/IL-13 in AD skin augmented LL-37 and inhibited VV replication. Cathelicidins were induced via toll-like receptor-3 and were inhibited by IL-4/IL-13 through STAT-6. Skin from cathelicidin-deficient mice exhibited reduced ability to control VV replication. Exogenous LL-37 controlled vaccinia viral replication in infected keratinocytes and AD skin explants. The current study demonstrates that Th2 cytokines enhance VV replication in AD skin by subverting the innate immune response against VV in a STAT-6-dependent manner.     

New insights into the role of T cells in pathogenesis of psoriasis and psoriatic arthritis

Psoriasis is a chronic, relapsing, autoimmune disorder of the skin affecting 2–3% of general population. Approximately 30% of psoriasis patients are also affected with the psoriatic arthritis, a chronic inflammatory spondyloarthritis. The review aims to present the current knowledge on immunopathogenesis of both diseases to emphasize the involvement of various T helper cell subsets. An extensive literature search in electronic databases was performed on the topic of different Th cell subsets’ involvement in the pathogenesis of psoriasis and psoriatic arthritis. Studies were assessed and selected to present the recent progress in the area. Current data strongly suggest that both PsO and PsA are T cell-mediated diseases, with a key role of various proinflammatory cytokines in their development. The involvement of T cells is highlighted by the superior efficacy of biologic therapies targeting T cell-derived proinflammatory cytokines in both diseases. Initially, PsO and PsA were thought to be Th1-mediated diseases; however, in the last years, several studies have shown the important role of other T cell subsets, including Th17, Th22, Th9 and Treg cells, in the pathogenesis of both diseases, which has led to the development of new therapies.     

Adalimumab for the treatment of psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory joint disease occurring in 6–39% of patients with psoriasis. Standard therapy of PsA includes nonsteroidal anti-inflammatory drugs, intra-articular steroids and disease-modifying antirheumatic drugs. Failure of standard therapy is an indication for anti-TNF-α therapy. Adalimumab – a fully human monoclonal antibody against TNF-α – is an effective and generally reasonably well-tolerated drug for treating signs and symptoms of PsA. In placebo-controlled clinical trials, adalimumab showed American College of Rheumatology (ACR)20 response rates of 39–58% and ACR50 response rates of 25–39% in patients with active PsA who had failed previous standard therapy. Significant improvement of psoriatic skin changes and disease-related quality of life were also noted. The response of joints and skin and quality of life improvement was sustained over 2 years of therapy. In addition, adalimumab suppressed structural joint damage and retards radiographic progression of PsA.     

Cationic antimicrobial peptides in psoriatic skin cooperate to break innate tolerance to self‐DNA

Psoriasis is a T‐cell‐mediated skin autoimmune disease characterized by the aberrant activation of dermal dendritic cells (DCs) and the sustained epidermal expression of antimicrobial peptides. We have previously identified a link between these two events by showing that the cathelicidin antimicrobial peptide LL37 has the ability to trigger self‐nucleic acid mediated activation of plasmacytoid DCs (pDCs) in psoriatic skin. Whether other cationic antimicrobial peptides exert similar activities is unknown. By analyzing heparin‐binding HPLC fractions of psoriatic scales, we found that human beta‐defensin (hBD)2, hBD3, and lysozyme are additional triggers of pDC activation in psoriatic skin lesions. Like LL37, hBD2, hBD3, and lysozyme are able to condense self‐DNA into particles that are endocytosed by pDCs, leading to activation of TLR9. In contrast, other antimicrobial peptides expressed in psoriatic skin including elafin, hBD1, and psoriasin (S100A7) did not show similar activities. hBD2, hBD3, and lysozyme were detected in psoriatic skin lesions in the vicinity of pDCs and found to cooperate with LL37 to induce high levels of IFN production by pDCs, suggesting their concerted role in the pathogenesis of psoriasis.     

Safety of anti-TNFα agents in the treatment of psoriasis and psoriatic arthritis

Context: The efficacy and favorable safety profile of anti-tumor necrosis factor (TNF) agents in the treatment of psoriasis and psoriatic arthritis (PsA) are supported by several randomized controlled studies and meta-analyses. However, some concerns on the long-term safety of these drugs still exist, as these studies generally included small patient numbers and were performed in selected patient populations.

Objective: This review presents and discusses current evidence on the safety of anti-TNFα agents in patients with psoriasis and PsA, with a focus on European registry studies and case reports of particular importance.

Methods: Key studies on the safety of anti-TNFα agents in the treatment of adult patients with psoriasis or PsA were identified by a MEDLINE search (last updated 10 November 2011) based on several interrelated queries, with a focus on European registries. Other studies and case reports were included if deemed relevant. Studies concerning other conditions, such as rheumatoid arthritis (RA), were included as appropriate when data in psoriatic disease were unavailable or insufficient.

Results: Available data on the safety of anti-TNFα agents such as etanercept in psoriasis and PsA appear reassuring, even if some concerns still exist. Most notably, data suggest a higher incidence of infection and lymphoma amongst patients treated with the anti-TNFα monoclonal antibodies infliximab and adalimumab compared with etanercept.

Conclusion: The overall safety profile of monoclonal antibodies in patients with psoriasis, PsA and RA seems less favorable than that of etanercept, particularly in terms of risk of infection and hepatotoxicity.     

Subjective Health Complaints in Individuals with Psoriasis and Psoriatic Arthritis: Associations with the Severity of the Skin Condition and Illness Perceptions – A Cross-Sectional Study

Purpose

High comorbidity has been reported among persons with psoriasis and psoriatic arthritis (PsA), but the occurrence of subjective health complaints (SHCs) in these patient groups is poorly understood. The study aimed to describe the prevalence of SHCs among individuals with psoriasis and PsA in Norway, and investigate whether the severity of their skin condition and their illness perceptions were associated with the number and severity of health complaints.

Method

Participants were recruited through the Psoriasis and Eczema Association of Norway (PEF) (n = 942). The participants answered a self-administered questionnaire covering subjective health complaints, the severity of their skin condition, and their illness perceptions measured with the Brief Illness Perception Questionnaire (BIPQ-R).

Results

The prevalence and severity of SHCs were high. Participants with PsA reported more complaints and higher severity of complaints compared with participants with psoriasis. In both groups, the severity of the skin condition was associated with the number and severity of SHCs. Cognitive illness perceptions (consequences) and emotional illness perceptions (emotional affect) were associated with SHCs in participants with psoriasis, whereas only cognitive illness perceptions (consequences and identity) were associated with SHCs in participants with PsA.

Conclusion

The high prevalence and severity of SHCs among individuals with psoriasis and PsA were associated with the severity of the skin condition and illness perceptions. Somatic and cognitive sensitizations are proposed as possible mechanisms. The findings suggest that holistic approaches are essential when managing these patient groups in health care institutions and clinical practice.

     

High values of alpha (CXCL10) and beta (CCL2) circulating chemokines in patients with psoriatic arthritis, in presence or absence of autoimmune thyroiditis

The possible role of circulating alpha and beta chemokines in psoriatic arthritis is not extensively studied. The aim of the study is to evaluate serum levels of CXCL10, CXCL9 (alpha) and CCL2 (beta) chemokines in a large series of psoriatic arthritis patients, with or without autoimmune thyroid (AT) disorders, and to relate chemokines levels to the clinical phenotype of these patients. Serum levels of CXCL10 and CCL2 were measured in 37 patients with psoriatic arthritis without AT (PsA) and 28 with AT (PsA+AT), and in gender- and age-matched (1:1) controls without (control 1) or with AT (control 2). Serum CXCL10 levels were significantly higher in control 2 than in control 1 (p < 0.001) and in PsA than control 1 or 2 (p < 0.0001). PsA+AT patients have CXCL10 higher than controls 1 and 2 (p < 0.0001, for both) and than PsA (p < 0.001). By defining a high CXCL10 level as a value at least 2 SD above the mean value of the control group (>192 pg/ml), 5% of control 1, 19% of control 2, 42% of PsA and 63% of PsA+AT, had high CXCL10 (p < 0.0001; chi(2)). Serum CCL2 levels were similar in controls 1 and 2. PsA or PsA+AT patients have serum CCL2 levels significantly (p < 0.01, for both) higher than controls 1 and 2. Serum CXCL9 was not significantly different in the study groups. In conclusion, our study demonstrates higher serum levels of CXCL10 and CCL2 chemokines in patients with PsA than in controls. Serum CXCL10 (alpha chemokine) levels in psoriatic arthritis patients are significantly higher in presence of AT.     

High prevalence of an IgG response against murine leukemia virus (MLV) in patients with psoriasis

Increasing evidence suggests that human endogenous retroviruses (HERV) could participate in the pathogenesis of autoimmune diseases such as multiple sclerosis and lupus erythematosus. To assess a possible association of murine leukemia virus (MLV)-like group of HERVs with psoriasis we searched for antibodies against MLV proteins in the sera of patients. We showed that anti-MLV antibodies (total) were detected in both psoriatic and control sera. However, they were detected with a higher frequency in psoriasis when compared with controls (91 vs. 53%, respectively, P=0.001). In addition, the IgG response was dramatically increased in psoriasis (86 vs. 8%, respectively, P<0.0001). This immunoreactivity was observed against the products of both the gag and env genes, and the most antigenic proteins were the gp65-70. Moreover, we observed that anti-p30 MLV antibodies reacted with an epidermal protein with a molecular weight of 50 kDa in protein extracts from both normal and psoriatic skin cultures. These observations suggest that HERVs of the MLV-like group could contribute to the immunopathogenesis of psoriasis.     

Psoriasis and cardiovascular disease: the elusive link

Psoriasis, an autoimmune inflammatory disease, with its most common coexisting condition, psoriatic arthritis, seem to be more than just a local skin or joint disease, as evidence has accumulated over the years that it is associated with cardiovascular disease (CVD), which may confer an increased cardiovascular event and death rate. The data come mostly from observational studies and meta-analyses and indicate a potential pathogenetic link between these two systemic diseases, however definite proof of this detrimental relationship awaits further prospective studies. Newer anti-psoriatic biologic therapies seem to confer a cardiovascular benefit, but this needs future randomized controlled studies to confirm. All these intricate issues of a potential link between psoriasis and CVD are discussed and elaborated in this overview, in an attempt to shed further light on pivotal aspects of the association between psoriasis and CVD.