Effects of topical calcipotriol on the expression of adhesion molecules in psoriasis

Vitamin D: sources, physiological role, biokinetics, deficiency, therapeutic use, toxicity, and overview of analytical methods for detection of vitamin D and its metabolites

Vitamin D has a well-known role in the calcium homeostasis associated with the maintenance of healthy bones. It increases the efficiency of the intestinal absorption of dietary calcium, reduces calcium losses in urine, and mobilizes calcium stored in the skeleton. However, vitamin D receptors are present ubiquitously in the human body and indeed, vitamin D has a plethora of non-calcemic functions. In contrast to most vitamins, sufficient vitamin D can be synthesized in human skin. However, its production can be markedly decreased due to factors such as clothing, sunscreens, intentional avoidance of the direct sunlight, or the high latitude of the residence. Indeed, more than one billion people worldwide are vitamin D deficient, and the deficiency is frequently undiagnosed. The chronic deficiency is not only associated with rickets/osteomalacia/osteoporosis but it is also linked to a higher risk of hypertension, type 1 diabetes, multiple sclerosis, or cancer. Supplementation of vitamin D may be hence beneficial, but the intake of vitamin D should be under the supervision of health professionals because overdosing leads to intoxication with severe health consequences. For monitoring vitamin D, several analytical methods are employed, and their advantages and disadvantages are discussed in detail in this review.

Inhibition of dipeptidyl-peptidase 4 induces upregulation of the late cornified envelope cluster in keratinocytes

Dipeptidyl-peptidase 4 (DPP4) is a multifunctional type II transmembrane glycoprotein that is expressed on various cell surfaces. While DPP4 inhibitors have a therapeutic role in the treatment of diabetes mellitus, they are an independent risk factor in the development of bullous pemphigoid. Contrarily, there are reports of improvement in psoriasis with DPP4 inhibition. We investigated the effect of DPP4 inhibition on primary human keratinocytes to determine whether DPP4 modulates keratinocyte inflammatory signaling and keratinocyte homeostasis. We performed RNA sequencing of primary adult human keratinocytes treated with DPP4 inhibitor, identifying 424 differentially expressed genes. Gene ontology analysis revealed significant enrichment of epidermal differentiation and cornified envelope genes. Using three-dimensional organotypic cultures and a pan-late cornified envelope 2 (LCE2) antibody, we demonstrate a dose dependent relationship between DPP4 inhibition and increased expression of LCE2 during epidermal development. The late cornified envelope gene clusters are expressed at the late stages of epithelial development, responding to stimuli such as calcium and ultraviolet light. While its biologic function is not fully understood, mutations in LCE3B/LCE3C confer a 40% increased risk in the development of plaque psoriasis. While we did not identify significant modulation of keratinocyte inflammatory markers, DPP4 inhibition increased expression of the late cornified envelope may offer a potential alternative therapeutic mechanism in psoriasis.

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 role of Dipeptidyl Peptidase-4 in cutaneous disease

Dipeptidyl peptidase-4 (DPP4) is a multifunctional, transmembrane glycoprotein present on the cell surface of various tissues. It is present in multiple molecular forms including cell surface and soluble. The role of DPP4 and its inhibition in cutaneous dermatoses have been a recent point of investigation. DPP4 exerts a notable influence on T-cell biology, the induction of skin-specific lymphocytes, and the homeostasis between regulatory and effector T cells. Moreover, DPP4 interacts with a broad range of molecules, including adenosine deaminase, caveolin-1, CXCR4 receptor, M6P/insulin-like growth factor II-receptor and fibroblast activation protein-α, triggering downstream effects that modulate the immune response, cell adhesion and chemokine activity. DPP4 expression on melanocytes, keratinocytes and fibroblasts further alters cell function and, thus, has crucial implications in cutaneous pathology. As a result, DPP4 plays a significant role in bullous pemphigoid, T helper type 1-like reactions, cutaneous lymphoma, melanoma, wound healing and fibrotic disorders. This review illustrates the multifactorial role of DPP4 expression, regulation, and inhibition in cutaneous diseases.

Association between psoriasis and vitamin D: Duration of disease correlates with decreased vitamin D serum levels: An observational case-control study

Recent literature has focused on the association of psoriasis with lower than normal or highly deficient vitamin D blood levels.To investigate the controversial association between psoriasis and vitamin D levels.From 2012 to 2014, 561 subjects were assessed, of which 170 had psoriasis, 51 had an autoimmune bullous, and 340 were healthy patients. Anagraphical data, 25(OH)D blood levels, and seasons of vitamin D levels assessments were recorded for each group.Vitamin D levels were significantly different among the 3 groups (K = 151.284; P = .0001). Psoriatic patients had significantly lower serum levels of 25(OH)D (21.8 ng/mL) than healthy controls (34.3 ng/mL) (chi-square = 11.5; P = .0007). Patients with bullous diseases showed the lowest vitamin D mean values (18.2 ng/mL). The linear multiple regression model showed 25(OH)D levels to be influenced by age, season of blood vitamin D levels assessment, and psoriasis duration.These results confirm the reduced vitamin D levels in psoriatic patients when compared to healthy controls, and provide new evidence regarding the association of vitamin D levels and psoriasis duration. The limits of our study include its observational nature and the small number of patients undergoing biological immunosuppressive therapies.

The role of vitamin D in psoriasis: a review

BACKGROUND AND OBJECTIVE

Psoriasis is a common, chronic autoimmune inflammatory skin disorder, which has potential systemic complications and is clinically defined by sharply demarcated, erythematous patches and plaques covered by a characteristic silvery white scale. Topical corticosteroids have widely been regarded as the mainstay first line of treatment. Recently, topical vitamin D analogs have been added to the first-line treatment repertoire as well, either as monotherapy or in combination with topical steroids due to synergistic, complementary effectiveness. In this paper, we review the role of vitamin D in the pathophysiology and treatment of psoriasis.

METHODS

A comprehensive search of the Cochrane Library, MEDLINE, and PUBMED databases were performed to identify relevant basic science and clinical trial literature investigating the role of vitamin D in psoriasis. Primary endpoints in clinical trials were largely based on clinical improvement as assessed by the psoriasis area severity index score or physician's global assessment.

RESULTS AND CONCLUSION

The role of vitamin D in psoriasis is complex and extensive. Oral and topical vitamin D therapies provide comparable efficacies to corticosteroids when used as monotherapy and may be superior when used in combination with a potent topical steroid. Additionally topical vitamin D analogs demonstrate a favorable safety profile with "steroid-sparing" effects. Thus, topical vitamin D derivatives should be considered an indispensable component of the current physician's arsenal in the treatment of psoriasis.

CD26/dipeptidyl-peptidase IV and adenosine deaminase serum levels in psoriatic patients treated with cyclosporine, etanercept, and psoralen plus ultraviolet A phototherapy

OBJECTIVE

The aim of this study is to determine serum levels of soluble forms of CD26/dipeptidyl-peptidase IV (DPP-IV) and adenosine deaminase (ADA), thought to be markers of T-cell activation, and changes in their levels in response to cyclosporine, etanercept, and psoralen plus ultraviolet A (PUVA) treatments with respect to disease activity.

METHODS

This study is designed as a prospective clinical study with a control group and three months of follow-up. The study included 41 patients with psoriasis and 41 healthy controls that were older than 18years of age. There were three different treatment groups: PUVA (n=15), cyclosporine (n=15), and etanercept (n=11). To determine disease severity of patients with psoriasis, psoriasis area and severity index (PASI) scores were calculated.

RESULTS

Only mean serum ADA levels were different between patients with psoriasis [mean1±standard deviation (SD)=13.9±3.3U/ml] and control group (mean±SD=12±3.5U/ml). Mean serum ADA levels were significantly higher before treatment than after treatment (mean±SD=12.4±3.4U/ml). Contrarily, following three months of therapy, mean serum CD26 levels increased significantly from 777.7±214.6 to 835.3±203ng/ml (P<0.05) and mean serum DPP-IV activity increased significantly from 12.1±4 to 15.9±4.2nmol/min (P<0.05). There was no correlation between ADA and CD 26/DPP-IV with PASI values.

CONCLUSIONS

 The results show that ADA might be a useful marker indicating disease activity and T-cell activation. As significant changes were observed in serum CD26/DPP-IV before and after treatment, we think CD26/DPP-IV might play a role in psoriasis pathogenesis, which should be clarified by further studies.

In vivo pharmacological disease models for psoriasis and atopic dermatitis in drug discovery

In order to perform relevant in vivo pharmacological investigations in drug discovery within dermatology it is fundamental to master or have access to relevant skin disease models that makes it possible to identify and validate targets and to screen and discover drugs in vivo. There is a strong need for highly predictive in vivo models in order to introduce the right drug candidates into the clinical phases of development. Recent advances in dermatological in vivo pharmacological disease models for psoriasis and atopic dermatitis are reviewed together with a discussion of the rationale for their application in drug discovery.

The changes in expression of ICAM-3, Ki-67, PCNA, and CD31 in psoriatic lesions before and after methotrexate treatment

Although the effectiveness of methotrexate (MTX) in the treatment of psoriasis is very well established, the mechanism of action is poorly understood. It was suggested that the therapeutic effect of MTX in psoriasis might be mediated by inhibition of adhesion molecule expression. The aim of our study was to investigate the different effects of MTX treatment on cell proliferation, inflammatory infiltrate, adhesion molecules, and angiogenesis in psoriasis, and to clarify the mechanism by which MTX exerts its therapeutic effects. Clinical response, the morpho-phenotypic changes, epidermal thickness, and mitosis count were analyzed and the expression of CD31 and ICAM-3, proliferative markers such as Ki-67, PCNA, were evaluated by immunohistochemical techniques in lesional psoriatic epidermis, before and after the treatment with MTX in ten patients. In posttreatment biopsies a decrease in the degree of epidermal hyperplasia and a significant reduction in the severity of the inflammatory infiltrate (P<0.05) were observed. In addition, CD31 and ICAM-3 expression was significantly decreased on dermal cellular infiltrate, (respectively; P<0.05, P<0.01). Ki67 and PCNA expression were suppressed concurrently in about 90% of cases (P<0.01). We suggest that MTX may have an inhibitory effect on an initial integral component of the pathways that lead to psoriasis. Immunopharmacologic intervention in adhesion event has the potential to improve psoriasis. Inhibition of revascularization may be another mechanism of action of MTX.

Identification of extra- and intracellular alanyl aminopeptidases as new targets to modulate keratinocyte growth and differentiation

Aminopeptidase inhibitors strongly affect proliferation, differentiation, and function of immune cells and show therapeutic potential in inflammatory disorders. In psoriatic lesions, keratinocytes display increased cellular turnover and disturbed differentiation, leading to epidermal hyperplasia accompanied by the loss of stratum granulosum. Here, we report in the HaCaT hyperproliferative keratinocyte cell line as well as in two primary keratinocyte strains in vitro a molecular and biochemical analysis of the expression of both membrane and cytosol alanyl aminopeptidase (cAAP) on the mRNA, protein, and enzymatic activity level. We found a clear dose-dependent suppression of DNA synthesis in vitro in the presence of the inhibitors actinonin, bestatin, and the cAAP-specific inhibitor PAC-22 correlating well with the simultaneous decrease in enzyme activity. In vivo, actinonin dose-dependently restored the stratum granulosum and ameliorated the impaired keratinocyte differentiation in the mouse tail model of psoriasis. Taken together, these data suggest that targeting alanyl aminopeptidases may be beneficial for psoriasis and other inflammatory skin disorders.

Tocoretinate inhibited the contraction of collagen gel matrices by human dermal fibroblasts with tenascin-C expression

Retinoids are strong tissue modifiers and have been used to treat severe acne, keloids and photo-aged skin. Tocoretinate (TR), ester bound retinoic acid and tocopherol, has been topically applied for skin ulcers and, more recently, for sclerotic skin diseases. To clarify the mechanism of tissue softening by retinoids and TR, we investigated their effects on the contraction of hydrated type-1 collagen gel matrices by human dermal fibroblasts and on tenascin-C expression. TR, 13-cis-retinoic acid/isotretinoin and all trans-retinoic acid significantly inhibited collagen gel matrices contraction at concentrations from 10(-4) to 10(-8) M without significant changes of the fibroblast growth. TR and the other two retinoids dose-dependently induced tenascin-C expression in the fibroblasts. Since tenascin-C is involved in cellular detachment and tissue remodeling, these results suggest that TR and other retinoids down-regulated the tensile tension of fibroblasts in collagen gel matrices by the induction of tenascin-C.