The inhibitory effect of VitD3 on proliferation of keratinocyte cell line HACAT is mediated by down-regulation of CXCR2 expression

Serum 25-OH Vitamin D Level in Psoriatic Patients and Comparison With Control Subjects

Background:

Vitamin D has been shown to have immunomodulatory effects, and previous studies have proposed a role of vitamin D deficiency in multiple autoimmune diseases, including psoriasis.

Objectives:

The aim of this study was to investigate serum vitamin D levels in psoriatic patients and compare them with levels in controls.

Methods:

This study was carried out in 50 psoriasis patients. Serum vitamin D was measured by enzyme-linked immunosorbent assay.

Results:

The mean serum vitamin D levels in psoriatic patients and controls were 14.92 ± 6.31 and 12.52 ± 4.54 ng/mL, respectively. The difference was not statistically significant ( P = .06). The prevalence of vitamin D deficiency (<20 ng/mL) was 84.0% in psoriatic patients and 93.0% in controls ( P = .21).

Conclusions:

Most of the patients with psoriasis had vitamin D deficiency, which may have contributed to the evolution of their psoriasis. However, considering the high prevalence of vitamin D deficiency in Iran, no difference was noted between the psoriatic patients and the controls.

PHF11 expression and cellular distribution is regulated by the Toll-Like Receptor 3 Ligand Polyinosinic:Polycytidylic Acid in HaCaT keratinocytes

Background

Inflammatory skin diseases such as atopic dermatitis and psoriasis represent a complex interaction between the skin and infiltrating immune cells, resulting in damage to the skin barrier and increased inflammation. Polymorphisms in PHF11 have been associated with dermatitis and allergy and PHF11 regulates the transcription of T-cell cytokines as well as class switching to IgE in activated B-cells. The importance of skin barrier homeostasis in the context of inflammatory skin diseases, together with reports identifying PHF11 as an interferon-induced gene, have led us to examine its role in the innate immune response of keratinocytes.

Results

We developed a cell culture model that allowed us to analyze the effects of the double-stranded RNA analogue poly(I:C) on a confluent cell monolayer immediately after a 24-h treatment, as well as three days after withdrawal of treatment. Immediately after treatment with poly(I:C), PHF11, IL8, and interferon-dependent ISG15 RNA expression was increased. This was accompanied by nuclear localization of PHF11 as well the tight junction protein claudin-1. Knock-down of PHF11 resulted in increased interleukin-8 expression and secretion immediately following treatment with poly(I:C), as well as changes in the cellular distribution of membrane-bound and increased nuclear claudin-1 that was observed up to 3 days after the withdrawal of poly(I:C). This was associated with lower cell density and a decrease in the number of cells in the G1 phase of the cell cycle.

Conclusions

In addition to a role for PHF11 in lymphocyte gene expression, we have now shown that PHF11 was part of the keratinocyte innate immune response by poly(I:C). As knock-down of PHF11 was associated with increased expression of the pro-inflammatory chemokine IL-8 and changes in the cellular distribution of claudin-1, a change normally associated with increased proliferation and migration, we suggest that PHF11 may contribute to epidermal recovery following infection or other damage.

Vitamin D status in patients with chronic plaque psoriasis

BACKGROUND

Vitamin D could have important immunomodulatory effects in psoriasis.

OBJECTIVES

To measure 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH) and calcium serum levels in patients with psoriasis and the associations with some relevant clinical features.

METHODS

A cross-sectional study was conducted over 1 year including 145 patients with chronic plaque psoriasis, 112 patients with rheumatoid arthritis (RA) and 141 healthy controls. 25(OH)D, PTH and calcium serum levels were measured in a centralized laboratory. Demography, comorbidities, disease severity and exposure time to sunlight (which was derived by questionnaire) were collected.

RESULTS

The prevalence of vitamin D deficiency [25(OH)D levels <20ngmL(-1) ] in patients with psoriasis was 57·8% vs. 37·5% in patients with RA and 29·7% in healthy controls (P<0·001). In winter, the prevalence of vitamin D deficiency rose to 80·9% in patients with psoriasis, to 41·3% in those with RA and to 30·3% in healthy controls (P<0·001). Patients with psoriasis or psoriatic arthritis did not differ in 25(OH)D serum levels nor in the prevalence of vitamin D deficiency. In the logistic regression analysis, vitamin D deficiency was associated with psoriasis independently of age, sex, body mass index, calcium, PTH levels and season of blood sampling. A limitation is that the study design does not allow a causal or temporal relationship between vitamin D deficiency and psoriasis to be established.

CONCLUSIONS

Vitamin D deficiency may be common in patients with psoriasis, especially in winter.

Impact of aryl hydrocarbon receptor (AhR) knockdown on cell cycle progression in human HaCaT keratinocytes

Abstract While activation of the aryl hydrocarbon receptor (AhR) by exogenous ligands is well investigated, its physiological function is less understood. By extending research in AhR biology, evidence appeared that the receptor generally plays an important role in cell physiology. In keratinocytes, little is known about endogenous functions of the AhR. In order to expand this knowledge, we analyzed the impact of AhR knockdown on cell cycle progression in HaCaT cells and showed that proliferation of siAhR HaCaT cells was significantly decreased. In line with that result, western blot analysis revealed that protein level of the cyclin dependent kinase inhibitor p27(KIP1) was increased, whereas protein level of the cyclin dependent kinase (CDK) 2 was reduced. CDK4 and CDK6 protein levels remained unchanged, whereas protein level of the retinoblastoma protein (pRB) was reduced. By measuring ethoxyresorufin-O-deethylase (EROD) activity we showed that endogenous cytochrome P450 1 (CYP1), especially CYP1A1 is required for normal cell cycle in HaCaT cells, as well. To the best of our knowledge, we provide evidence for the first time in human skin cells, that in the absence of exogenous ligands, the AhR promotes cell cycle progression in HaCaT cells and one can speculate that this is the physiological function of this receptor in keratinocytes.

HIF-1alpha regulates epithelial inflammation by cell autonomous NFkappaB activation and paracrine stromal remodeling

Hypoxia inducible factor-1 (HIF-1) is a master regulatory transcription factor controlling multiple cell-autonomous and non-cell-autonomous processes, such as metabolism, angiogenesis, matrix invasion, and cancer metastasis. Here we used a new line of transgenic mice with constitutive gain of HIF-1 function in basal keratinocytes and demonstrated a signaling pathway from HIF-1 to nuclear factor kappa B (NFkappaB) activation to enhanced epithelial chemokine and cytokine elaboration. This pathway was responsible for a phenotypically silent accumulation of stromal inflammatory cells and a marked inflammatory hypersensitivity to a single 12-O-tetradecanoylphorbol-13-acetate (TPA) challenge. HIF-1-induced NFkappaB activation was composed of 2 elements, IkappaB hyperphosphorylation and phosphorylation of Ser276 on p65, enhancing p65 nuclear localization and transcriptional activity, respectively. NFkappaB transcriptional targets macrophage inflammatory protein-2 (MIP-2/CXCL2/3), keratinocyte chemokine (KC/CXCL1), and tumor necrosis factor [alfa] (TNFalpha) were constitutively up-regulated and further increased after TPA challenge both in cultured keratinocytes and in transgenic mice. Whole animal KC, MIP-2, or TNFalpha immunodepletion each abrogated TPA-induced inflammation, whereas blockade of either VEGF or placenta growth factor (PlGF) signaling did not affect transgenic inflammatory hyper-responsiveness. Thus, epithelial HIF-1 gain of function remodels the local environment by cell-autonomous NFkappaB-mediated chemokine and cytokine secretion, which may be another mechanism by which HIF-1 facilitates either inflammatory diseases or malignant progression.

Human CXCR2 (hCXCR2) takes over functionalities of its murine homolog in hCXCR2 knockin mice

Human CXCR2 (hCXCR2) has been implicated in diverse inflammatory diseases. When roles of this receptor studied in animal models are extrapolated into men, large species differences in expression of the receptor and its ligands must be considered. These differences seriously weaken conclusions toward the role of hCXCR2 in the development of human diseases. It furthermore hampers straightforward testing of CXCR2 antagonists, especially when compounds discriminate between human and other species' receptors. Using gene targeting in embryonic stem cells, a hCXCR2 knockin mouse strain was generated in which endogenous murine CXCR2 (mCXCR2) sequences are replaced by the hCXCR2 gene. Correct targeting and expression on neutrophils were confirmed by Southern blot and immunohistochemical analyses. A phenotypic analysis of the hCXCR2 knockin mice, in comparison to wild-type and CXCR2 knockout mice, confirmed proper function of the hCXCR2 gene. In vivo migratory responses of neutrophils were intact in hCXCR2 knockin mice. Finally, an experiment with a CXCR2 antagonist demonstrated that the knockin model is indeed useful for in vivo evaluation of low-molecular weight compounds. In conclusion, our data unequivocally show that hCXCR2 can functionally replace mCXCR2, making this an attractive model to test novel pharmaceuticals designed to antagonize human CXCR2 in vivo.