Effect of PUVA, narrow-band UVB and cyclosporin on inflammatory cells of the psoriatic plaque

Role of resolvin D1 in psoriasis before and after narrowband ultraviolet B phototherapy: A case-control study

Resolvin D1 (RvD1) is an endogenous lipid mediator that originated from docosahexaenoic acid that stimulates a bimodal mechanism in the anti-inflammatory activity in addition to regulation of the inflammatory reaction. The study aimed at assessing the tissue level of RvD1 in psoriasis to study its role in the etiopathogenesis of psoriasis, studying the action of NB-UVB on the level of resolvin D1 in psoriasis, and raising the possibility of using resolvin D1 as a new therapy for psoriasis in the future. This case-control study included 20 psoriasis patients and 20 healthy controls. Patients took narrowband ultraviolet B (NB-UVB) for 36 sessions. Skin biopsies were taken before and after treatment from patients and from controls to assess the expression of RvD1 by a quantitative real-time polymerase chain reaction. Our findings revealed a statistically significant difference (P < .001) between psoriasis patients (either before or after treatment) and controls with lower levels of RvD1 in psoriasis patients. On comparing the RvD1 levels in psoriasis patients before and after treatment, a statistically significant increase was detected after treatment (P < .001). Tissue RvD1 levels in psoriasis patients were lower than healthy controls and increased after NB-UVB treatment in psoriasis patients. Thus, it is suggested that RvD1 might have a role in the etiopathogenesis of psoriasis. Moreover, the significantly up-regulated tissue levels of RvD1 in patients after treatment with NB-UVB highlighted a novel mechanism of phototherapy-mediated response in psoriasis by up-regulating RvD1 level.

Evaluation of the Langerhans cells role in vitiligo and its relationship to NB-UVB

BACKGROUND

Langerhans cells (LCs) are antigen-presenting cells that are characterized by CD1a and CD207/langerin expression. The disturbance in the communication network among keratinocytes, melanocytes, and antigen-presenting cells may be involved in vitiligo pathogenesis.

AIMS

The current work aims to detect and quantify LCs in involved skin of patients affected by vitiligo before and after treatment with NB-UVB using CD1a immunohistochemistry, in addition to correlate percentage of LCs with the clinicopathological parameters.

METHODS

Twenty vitiligo patients and 10 age and sex matched controls were investigated. Patients were received NB-UVB thrice weekly for 12 weeks.

RESULTS

There was a significant reduction in LCs percentage in skin affected by vitiligo before treatment in comparison with normal skin. About 65% (13/20) of vitiligo patients responded to NB-UVB, and the liability to respond was correlated with LCs percentage in specimens before treatment. However, there was no statistical difference between specimens before and after treatment regarding LCs percentage.

CONCLUSIONS

Reduction in LCs in vitiligo may be a sign of active disease and melanocytes destruction. The percentage of LCs affects response to NB-UVB since higher percentage is associated with greater response to therapy. Therefore, modulation of LCs as a type of immunotherapy could be beneficial in improvement of vitiligo.

A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer

UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.

The efficacy of UVA1 phototherapy in psoriasis: Clinical and histological aspects

BACKGROUND

Although ultraviolet A1 (UVA1) phototherapy is available for nearly 30 years, only few studies have been conducted for plaque-type psoriasis.

OBJECTIVES

To determine the efficacy and safety of UVA1 phototherapy in psoriasis by assessing the clinical and histological outcomes.

METHODS

This open study enrolled 15 patients with moderate to severe plaque-type psoriasis. All of the patients had skin type IV. A whole-body UVA1 device consisting of 24 lamps, was irradiated at a medium dose of 50 J/cm² three-times weekly for 30 sessions. Topical and systemic psoriasis treatments were discontinued before and during treatment; patients could only use emollients and antihistamines until 1-month post-completion. Psoriasis Area and Severity Index (PASI) scores were determined at baseline; at sessions 10th, 20th and 30th; and 1 month after treatment. Four-millimetre punch biopsies were obtained from the same psoriasis lesion at baseline and session 30th. Changes in histopathological gradings and polymorphonuclear, lymphocyte and Langerhans cell numbers were monitored.

RESULTS

Twelve patients completed the study. The mean age was 41.3 years (range: 25-71). The median PASI scores at baseline, session 30th and 1-month post-treatment were 16 (8.2, 43.3), 11 (4.4, 43.3) and 9.2 (2.7, 36.4), respectively. Although the PASI scores had improved significantly by 1-month post-treatment (P = .006), the histological parameters demonstrated minimal changes. All patients tolerated the phototherapy well and the most common side effect was skin tanning.

CONCLUSIONS

While medium-dose UVA1 phototherapy demonstrated some efficacy in moderate to severe plaque-type psoriasis. However, it might not be an excellent choice.

Human Langerhans Cells with Pro-inflammatory Features Relocate within Psoriasis Lesions

Psoriasis is a common skin disease that presents with well-demarcated patches of inflammation. Recurrent disease in fixed areas of the skin indicates a localized disease memory that is preserved in resolved lesions. In line with such concept, the involvement of tissue-resident immune cells in psoriasis pathology is increasingly appreciated. Langerhans cells (LCs) are perfectly placed to steer resident T cells and local tissue responses in psoriasis. Here, we present an overview of the current knowledge of LCs in human psoriasis, including findings that highlight pro-inflammatory features of LCs in psoriasis lesions. We also review the literature on conflicting data regarding LC localization and functionality in psoriasis. Our review highlights that further studies are needed to elucidate the molecular mechanisms that drive LCs functionality in inflammatory diseases.

Up-regulated expression of CD86 on circulating intermediate monocytes correlated with disease severity in psoriasis

BACKGROUND

The number of intermediate monocytes (CD14⁺⁺CD16⁺) increases in many inflammatory conditions. However, it is not yet known which functional markers expressed by these populations are linked to the pathogenesis of psoriasis.

OBJECTIVES

We evaluated the expression of functional markers on circulating intermediate monocytes. Our goal was to correlate specific populations and their markers with the clinical severity of psoriasis.

METHODS

A cohort of 43 psoriatic patients was subjected to analysis. The proportion of intermediate monocytes with CD86 expression was evaluated by flow cytometry. Serum beta defensin-2 levels were measured by ELISA. Immunofluorescent staining was performed in order to identify the presence of CD14⁺CD16⁺ cells that co-expressed CD86 in affected skin tissues.

RESULTS

Upregulated expression of CD86 on the intermediate subset (but not the number of intermediate monocytes) correlated with clinical severity as measured by PASI scores and serum beta defensin-2 levels. Immunostaining also showed the presence of CD86⁺CD14⁺CD16⁺ cells in the epidermis and dermis of psoriatic plaques, which was associated with increased epidermal proliferation.

CONCLUSION

These results suggest that the expression of CD86 on circulating intermediate monocytes could be used as an index in clinical practice and provide novel insights into how these cells join a complex immune network under the pathological conditions of psoriasis.

NB-UVB irradiation downregulates keratin-17 expression in keratinocytes by inhibiting the ERK1/2 and STAT3 signaling pathways

Keratin-17 (K17) is a cytoskeletal protein produced by keratinocytes (KCs), which is overexpressed in psoriasis and may play a pivotal role in its pathogenesis. Narrow-band ultraviolet B (NB-UVB) irradiation is used as a general treatment for psoriasis, although its impact on K17 expression has yet to be determined. In this study, we aimed to investigate the effect of NB-UVB irradiation on K17 expression and its signaling pathways. After exposure to NB-UVB irradiation, immortalized human keratinocytes (HaCaT cells) were analyzed by flow cytometry, CCK-8 assays and transmission electron microscopy to examine proliferation. Meanwhile, K17 expression in primary human epithelial keratinocytes was detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis and immunofluorescence. HaCaT cells pre-incubated with PD-98059 and piceatannol were subjected to western blot analysis to examine ERK1/2 and STAT3 phosphorylation. The ears of mice treated with imiquimod (IMQ) and irradiated by NB-UVB were taken to examine K17 expression by qRT-PCR, western blot analysis, and immunofluorescence. Our results showed that 400 mJ/cm² of NB-UVB irradiation was the maximum tolerable dose for HaCaT cells and could cause inhibited HaCaT cell proliferation and moderate increase of the early apoptosis. Furthermore, NB-UVB irradiation could downregulate K17 expression by inhibiting the ERK1/2 and STAT3 signaling pathways. In experiments conducted in vivo, NB-UVB irradiation with doses of MED or higher could eliminate the IMQ-induced psoriasis-like dermatitis and inhibit K17 expression. These results indicated that NB-UVB irradiation may eliminate chronic psoriatic plaques by suppressing K17 expression via the ERK1/2 and STAT3 signaling pathways.

Dynamic Changes in Resident and Infiltrating Epidermal Dendritic Cells in Active and Resolved Psoriasis

Epidermal Langerhans cells (LCs) are spatially separated from dermal dendritic cells (DCs) in healthy human skin. In active psoriasis, maintained by local production of IL-23 and IL-17, inflammatory DCs infiltrate both skin compartments. Here we show that CCR2⁺ epidermal DCs (eDCs) were confined to lesional psoriasis and phenotypically distinct from dermal DCs. The eDCs exceeded the number of LCs and displayed high expression of genes involved in neutrophil recruitment and the activation of keratinocytes and T cells. Resident LCs responded to toll-like receptor 4 and toll-like receptor 7/8 activation with increased IL-23 production, whereas eDCs additionally produced IL-1β together with IL-23 and tumor necrosis factor. Psoriasis typically recur in fixed skin lesions. eDCs were absent from resolved psoriasis. Instead, LCs from anti-tumor necrosis factor-treated lesions retained high IL23A expression and responded to toll-like receptor stimulation by producing IL-23. Our results reveal phenotypic and functional properties of eDCs and resident LCs in different clinical phases of psoriasis, and the capacity of these cells to amplify the epidermal microenvironment through the secretion of IL-17 polarizing cytokines.

Photochemotherapy of Cutaneous Graft-versus-Host Disease May Reduce Concomitant Visceral Disease

BACKGROUND

Photochemotherapy may be used to treat cutaneous graft-versus-host disease (GvHD). Animal models show that in the days after photochemotherapy and antigen provocation, cells with an antigen-specific suppressive phenotype are elicited in the lymphoid organs. In GvHD, host antigens are present not only in the skin treated by photochemotherapy but also in the visceral tissues.

OBJECTIVE

The aim of this paper was to evaluate the effect on visceral acute GvHD (aGvHD) of photochemotherapy of the skin.

METHODS

We retrospectively evaluated 33 patients with aGvHD of the skin, the liver, and/or the gastrointestinal tract treated with photochemotherapy for their aGvHD of the skin and did a long-term follow-up of 10 years on survival.

RESULTS

The complete response (CR) to photochemotherapy was 39%, the complete and partial response was 64% and the 6-month survival was 64%. Total body irradiation (TBI) before hematopoietic stem cell transplantation predisposed for CR of aGvHD of the liver and the gastrointestinal tract (p = 0.045). In the TBI group, the accumulated dose (numbers of treatments) for CR of visceral aGvHD increased with the body surface area affected by disease, from 8 (min-max: 5-14) for skin disease stage 1 to 10.5 (6-33) for stage 2 and 13 (11-21) for stage 3 (p = 0.04). Skin disease stage 1 showed a trend to be associated with CR in visceral disease at 28, 56, and 100 days (p = 0.07). Overall CR in visceral disease predicted a better 10-year overall survival (p = 0.0036). Finally, after TBI aGvHD of the gastrointestinal tract without anti-thymocyte globulin (ATG), clearance of T cells and dendritic cells responded better than aGvHD of the liver and aGvHD of the gastrointestinal tract with ATG (p = 0.01).

CONCLUSION

Photochemotherapy after ionizing irradiation regulates the cell-mediated immunity in the viscera, and the systemic efficacy increases when the skin itself is less affected by disease. ATG modulates the regulatory effect of the gastrointestinal tract.

Counter-regulation of T cell effector function by differentially activated p38

Unlike the MAP kinase (MAPK) cascade that phosphorylates p38 on the activation loop, T cell receptor (TCR) signaling results in phosphorylation on Tyr-323 (pY323, alternative pathway). Using mice expressing p38α and p38β with Y323F substitutions, we show that alternatively but not MAPK cascade-activated p38 up-regulates the transcription factors NFATc1 and IRF4, which are required for proliferation and cytokine production. Conversely, activation of p38 with UV or osmotic shock mitigated TCR-mediated activation by phosphorylation and cytoplasmic retention of NFATc1. Notably, UVB treatment of human psoriatic lesions reduced skin-infiltrating p38 pY323(+) T cell IRF4 and IL-17 production. Thus, distinct mechanisms of p38 activation converge on NFATc1 with opposing effects on T cell immunity, which may underlie the beneficial effect of phototherapy on psoriasis.

Evaluation of PUVA-Induced Skin Side Effects in Patients Referred to the Imam Reza Hospital of Mashhad in 2005-2007

BACKGROUND

Systemic oral psoralens plus UVA therapy (PUVA) is a therapeutic method used with considerable success in many different skin disorders. PUVA therapy causes some cutaneous and noncutaneous side effects and in the present research we deal with cutaneous side effects.

AIMS

Evaluation of patients to know the different skin side effects of PUVA and their importance.

MATERIALS AND METHODS

All patients referred to the phototherapy unit of Imam Reza Hospital of Mashhad entered the research and skin examination was taken place initially and every 3 months thereafter. Whenever any side effect appeared, it was recorded in the information sheet.

RESULTS

One hundred and twenty-eight patients were included in the research, 61 were male between 15 and 75 years and 67 were female between 10 and 61 years of age. Age of female patients at the time of cutaneous side effect appearance was less than male patients. The most common early side effect was pruritus (34.3%) and the rarest was telangiectasia (0.7%). One case of late side effect in the form of squamous cell carcinoma was observed in a patient who had received other carcinogenic drugs as well. Complications such as skin dryness, pruritus, erythema and burning sensation occurred at low doses of UVA, while dermatitis, severe limb pain and acne at moderate doses and PUVA lentigines, hypertrichosis and lichenoid lesions appeared at high doses of UVA.

CONCLUSION

Considering the significant therapeutic effects and few serious side effects, PUVA therapy is a suitable and safe method for treatment of certain skin diseases.

Effect of Narrow Band Ultraviolet B Therapy versus Methotrexate on Serum Levels of Interleukin-17 and Interleukin-23 in Egyptian Patients with Severe Psoriasis

Background. There is raised interest in the involvement of interleukin-(IL-)23/T-helper 17 cells (Th17) axis in the pathogenesis of psoriasis. Objectives. To compare the effect of narrow band ultraviolet B (NB-UVB) and methotrexate (MTX) therapy on serum levels of IL-17 and IL-23 in psoriatic patients. Methods. Thirty patients with severe plaque psoriasis were included: 15 patients received NB-UVB three times weekly (group I) and 15 patients received MTX 0.3 mg/kg per week (group II), both for 8 weeks. Before and after treatment, serum levels of IL-17 and IL-23 were investigated by ELISA technique and psoriasis area and severity index (PASI) was calculated. Results. After treatment, all patients showed a reduction in their PASI score, IL-17 and IL-23 serum levels with a nonsignificant difference between both therapeutic modalities (P value >0.05). A positive correlation was detected between the percent of reduction of IL-17, IL-23 and the percent of reduction of PASI score for patients receiving both treatments. No correlation was found between the percent of reduction of IL-17, IL-23 and duration of disease or age of all patients in this study. Conclusion. Interleukin-17 and IL-23 serum level may serve as a potential biomarker for predicting the prognosis and therapeutic response of NB-UVB or MTX in treating psoriasis.

Immunotargeting in the management of psoriasis

The treatment of psoriasis has been revolutionized since the introduction of biologic therapies. Prior to their introduction, it was unclear if psoriasis was primarily a keratinocyte signaling dysfunction or an autoimmune T-cell mediated pathway. Nonspecific T-cell targeting treatments had been used with some success, but they were limited by a narrow therapeutic index. The nonspecific nature of these agents was fraught with side effects, and the efficacy of these treatments pales in comparison to current treatments. The initial biologic molecules, alefacept and efalizumab, were not specific for any T-cell driven pathway, and neither are currently available in the USA. The successors to these early therapies have shown high efficacy and low side effects in psoriasis and other autoimmune diseases through the specific targeting of tumor necrosis factor-alpha (TNF-α). Since the initial use of antitumor necrosis factor agents, a renaissance in our understanding of psoriasis has been underway, leading to the elucidation of the T-helper 17 (Th17) from the Th1 pathway. With each new treatment, the pathogenesis for psoriasis continues to be more defined, allowing for improved targeted therapies and the ability to achieve new milestones in efficacy.

Effects of narrow band UVB (311 nm) irradiation on epidermal cells

Ultraviolet radiation (UVR) is known to be one of the most important environmental hazards acting on the skin. It was revealed that chronic exposure to UVR accelerates skin aging, induces immunosuppression and may lead to the development of skin cancers. On the other hand, UVR has been shown to be effective in the treatment of numerous skin diseases and thus, various phototherapy modalities have been developed to date. Narrow-band ultraviolet B (NB-UVB) emitting a light with a peak around 311 nm has been demonstrated to be effective in the treatment of various skin disorders; currently it is one of the most commonly used phototherapy devices. Despite NB-UVB has been developed more than 30 years ago, the exact mechanism of its therapeutic action remains poorly understood. To date, most of NB-UVB effects were attributed to its influence on immune cells; however, nearly 90% of NB-UVB irradiation is absorbed by epidermis and keratinocytes seem to be important players in mediating NB-UVB biological activity. Here, we have reviewed the current data about the influence of NB-UVB on epidermal cells, with a special emphasis on cell proliferation and death.

Molecular Mechanisms of UV-Induced Apoptosis and Its Effects on Skin Residential Cells: The Implication in UV-Based Phototherapy

The human skin is an integral system that acts as a physical and immunological barrier to outside pathogens, toxicants, and harmful irradiations. Environmental ultraviolet rays (UV) from the sun might potentially play a more active role in regulating several important biological responses in the context of global warming. UV rays first encounter the uppermost epidermal keratinocytes causing apoptosis. The molecular mechanisms of UV-induced apoptosis of keratinocytes include direct DNA damage (intrinsic), clustering of death receptors on the cell surface (extrinsic), and generation of ROS. When apoptotic keratinocytes are processed by adjacent immature Langerhans cells (LCs), the inappropriately activated Langerhans cells could result in immunosuppression. Furthermore, UV can deplete LCs in the epidermis and impair their migratory capacity, leading to their accumulation in the dermis. Intriguingly, receptor activator of NF-κB (RANK) activation of LCs by UV can induce the pro-survival and anti-apoptotic signals due to the upregulation of Bcl-xL, leading to the generation of regulatory T cells. Meanwhile, a physiological dosage of UV can also enhance melanocyte survival and melanogenesis. Analogous to its effect in keratinocytes, a therapeutic dosage of UV can induce cell cycle arrest, activate antioxidant and DNA repair enzymes, and induce apoptosis through translocation of the Bcl-2 family proteins in melanocytes to ensure genomic integrity and survival of melanocytes. Furthermore, UV can elicit the synthesis of vitamin D, an important molecule in calcium homeostasis of various types of skin cells contributing to DNA repair and immunomodulation. Taken together, the above-mentioned effects of UV on apoptosis and its related biological effects such as proliferation inhibition, melanin synthesis, and immunomodulations on skin residential cells have provided an integrated biochemical and molecular biological basis for phototherapy that has been widely used in the treatment of many dermatological diseases.

Radioprotective properties of tocopherol succinate against ionizing radiation in mice

Threats of nuclear and other radiologic exposures have been increasing but no countermeasure for acute radiation syndrome has been approved by regulatory authorities. In prior publications we have demonstrated the efficacy of tocopherol succinate (TS) as a promising radiation countermeasure with the potential to protect against lethal doses of ionizing radiation exposure. The aim of this study was to gain further insight regarding how TS protects mice against a lethal dose of radiation. CD2F1 mice were injected subcutaneously with 400 mg/kg of TS, and 24 h later exposed to (60)Co γ-radiation. Intestinal tissues or spleen/thymus were harvested after irradiation and analyzed for CD68-positive inflammatory cells and apoptotic cells by immunostaining of jejunal cross-sections. Comet assay was used to analyze DNA damage in various tissues. Phospho-histone H3(pH3) and the proliferating cell nuclear antigen (PCNA) were used as mitotic markers for immunostaining jejunal cross-sections. We observed that injecting TS significantly decreased the number of CD68-positive cells, DNA damage and apoptotic cells (BAX, caspase 3 and cleaved poly(ADP-ribose) polymerase-positive cells) as judged by various apoptotic pathway markers. TS treatment also increased proliferating cells in irradiated mice. Results of this study further support our contention that TS protects mice against lethal doses of ionizing radiation by inhibiting radiation-induced apoptosis and DNA damage while enhancing cell proliferation.

Effective treatment of psoriasis with narrow-band UVB phototherapy is linked to suppression of the IFN and Th17 pathways

Narrow-band ultraviolet-B (NB-UVB) phototherapy is an effective treatment for psoriasis. The molecular mechanisms underlying its efficacy are incompletely understood. To identify NB-UVB-induced molecular pathways that may account for its anti-inflammatory efficacy, gene expression profiling was performed using epidermal RNA from lesional and nonlesional skin from patients with psoriasis undergoing NB-UVB therapy. Downregulation of Th17 signaling pathway was observed during NB-UVB therapy in psoriatic epidermis. Strong inhibition of the Th17 pathway by UVB was confirmed in an ex vivo organ culture system by demonstrating reduced signal transducer and activator of transcription 3 (STAT3) phosphorylation and β-defensin-2 production. These results were further substantiated by demonstrating that NB-UVB inhibited the Th17-dependent psoriasis-like dermatitis in mice. Other pathways affected by NB-UVB therapy include the IFN signaling pathway, epidermal differentiation, and other well-known therapeutic targets in psoriasis, such as the glucocorticoid, vitamin D, peroxisome proliferator-activated receptor, and IL-4 signaling pathways. In conclusion, clinical improvement of psoriasis by NB-UVB is linked to suppression of Th17 and type I and type II IFN signaling pathways, which are critical in the pathogenesis of the disease. Our results show that clinically effective NB-UVB therapy is based on suppression of a broad range of important molecular pathways in psoriatic skin.

Harnessing dendritic cells in inflammatory skin diseases

The skin immune system harbors a complex network of dendritic cells (DCs). Recent studies highlight a diverse functional specialization of skin DC subsets. In addition to generating cellular and humoral immunity against pathogens, skin DCs are involved in tolerogenic mechanisms to ensure the maintenance of immune homeostasis, as well as in pathogenesis of chronic inflammation in the skin when excessive immune responses are initiated and unrestrained. Harnessing DCs by directly targeting DC-derived molecules or selectively modulate DC subsets is a convincing strategy to tackle inflammatory skin diseases. In this review we discuss recent advances underlining the functional specialization of skin DCs and discuss the potential implication for future DC-based therapeutic strategies.

Effective narrow-band UVB radiation therapy suppresses the IL-23/IL-17 axis in normalized psoriasis plaques

Narrow-band UVB radiation (NB-UVB) therapy offers a well-established treatment modality for psoriasis. However, despite the common use of this form of treatment, the mechanism of action of NB-UVB is not well understood. We studied a group of 14 patients with moderate-to-severe psoriasis treated with carefully titrated and monitored NB-UVB for 6 weeks. Lesional plaques were classified as normalized (n=8) or nonresponsive (n=6) based on their histological improvement and normalization. We characterized lesional myeloid dendritic cells (DCs) and T cells and their inflammatory mediators using immunohistochemistry and real-time PCR. NB-UVB suppressed multiple parameters of the IL-23/IL-17 pathway in normalized plaques, but not in nonresponsive plaques. NB-UVB decreased the numbers of CD11c(+) DCs, specifically CD1c(-)CD11c(+) "inflammatory" DCs, and their products, IL-20, inducible nitric oxide synthase, IL-12/23p40, and IL-23p19. Furthermore, effective NB-UVB suppressed IL-17 and IL-22 mRNAs, which strongly correlated with lesion resolution. Therefore, in addition to its known role in suppressing IFN-γ production, NB-UVB radiation therapy can also target the IL-17 pathway to resolve psoriatic inflammation.JID JOURNAL CLUB ARTICLE: For questions, answers, and open discussion about this article, please go to http://www.nature.com/jid/journalclub.

Epidermal Langerhans cells are not required for UV-induced immunosuppression

UV light can be highly beneficial in the treatment of skin disorders such as psoriasis. It is thought to cause immunosuppression by depleting or altering the function of epidermal Langerhans cells (LC). Our previous studies identified a novel langerin(+) dendritic cell in the dermis, distinct from LC in phenotype, circulation, and function. In this study, we determined the role of LC and dermal langerin(+) cells in UV suppression. UV light suppressed the CD8 T cell response to both contact hypersensitivity and epicutaneous protein immunization, and resulted in a dramatically altered phenotype of LC. UV light did not alter early CD8 T cell activation in the lymph nodes, but rather reduced CD8 T cell expansion at later time points. We found that dermal langerin(+) cells, but not LC, were essential for the CD8 T cell response. Furthermore, in the selective absence of LC, UV light still caused suppression of both CD8 T cell expansion and contact hypersensitivity.

Immunohistochemical analysis of small plaque parapsoriasis: involvement of dendritic cells

Small plaque parapsoriasis (SPP) is one of the cutaneous T-cell lymphoproliferative disorders. The aim of the present study was to show the antigenic profile of a subset of dendritic cells and lymphocytes in SPP in comparison with normal cells to provide data on the role of these two cell types in the pathogenesis of SPP. Skin biopsy specimens of lesions were obtained from 8 patients with SPP. Biopsies of the healthy skin from 9 control individuals were also analyzed. Immunohistochemistry was performed on the frozen tissue sections to reveal binding of anti-HLA Class II, anti-CD1a, anti-CD4, anti-CD8, anti-CD44, anti-CD45, and anti-CD68 monoclonal antibodies. There was a statistically significant increase in the number of CD1a(+), Langerhans cells (LCs), HLA-DR-immunoreactive and, CD1a-positive dermal dendritic cells and CD68(+) macrophages in the SPP group (p=0.008, 0.008, 0.002 and <0.0009, respectively). The number of lymphocytes positive for CD4, CD8 and CD45 was significantly higher than normal in the SPP group (p=0.015, <0.0009 and <0.0009, respectively). Our study demonstrates that both peptide- and lipid-based antigens are involved in the persistent antigenic exposure in SPP. Dendritic cells play a pivotal role in SPP by presenting antigens by both LC and dermal dendritic cells via MHC Class II and CD1a molecules. The CD68(+) macrophages are thought to be involved in the immune response in this pathology as an antigen-presenting cell.

Activation of Src-family tyrosine kinases in hyperproliferative epidermal disorders

BACKGROUND

Src-family tyrosine kinases (SFKs) are important regulators of keratinocyte growth and differentiation. In a broad range of cell types, persistent activation of SFKs correlates with increased cell proliferation. In this study, we determined if SFK activity is increased in cutaneous neoplasia and psoriasis, common hyperproliferative epidermal disorders.

METHODS

Formalin-fixed tissue sections of unremarkable epidermis, psoriasis, actinic keratoses (AKs), squamous cell carcinoma in situ (SCIS) and squamous cell carcinoma (SCC) were subjected to immunohistochemical staining for activated SFKs.

RESULTS

All psoriasis specimens displayed significantly greater staining for activated SFKs than sections of unremarkable skin. In the psoriasis biopsies, the degree of epidermal hyperplasia was proportional to the level of activated SFK staining. All AKs, SCISs and SCCs exhibited more prominent staining than sections of unremarkable epidermis. No discernable difference in activated SFK staining was seen between AKs, SCIS and SCC specimens.

CONCLUSIONS

This study shows increased staining of activated SFKs in human biopsy specimens of psoriasis and cutaneous neoplasia. These data provide direct evidence for increased activation of SFKs in the pathogenesis of hyperproliferative epidermal disorders.