Keratinocytes In Psoriatic Lesions Research Articles

The oncogenic kinase TOPK upregulates in psoriatic keratinocytes and contributes to psoriasis progression by regulating neutrophils infiltration

BackgroundT-LAK cell-oriented protein kinase (TOPK) strongly promotes the malignant proliferation of cancer cells and is recognized as a promising biomarker of tumor progression. Psoriasis is a common inflammatory skin disease featured by excessive proliferation of keratinocytes. Although we have previously reported that topically inhibiting TOPK suppressed psoriatic manifestations in psoriasis-like model mice, the exact role of TOPK in psoriatic inflammation and the underlying mechanism remains elusive.MethodsGEO datasets were analyzed to investigate the association of TOPK with psoriasis. Skin immunohistochemical (IHC) staining was performed to clarify the major cells expressing TOPK. TOPK conditional knockout (cko) mice were used to investigate the role of TOPK-specific deletion in IMQ-induced psoriasis-like dermatitis in mice. Flow cytometry was used to analyze the alteration of psoriasis-related immune cells in the lesional skin. Next, the M5-induced psoriasis cell model was used to identify the potential mechanism by RNA-seq, RT-RCR, and western blotting. Finally, the neutrophil-neutralizing antibody was used to confirm the relationship between TOPK and neutrophils in psoriasis-like dermatitis in mice.ResultsWe found that TOPK levels were strongly associated with the progression of psoriasis. TOPK was predominantly increased in the epidermal keratinocytes of psoriatic lesions, and conditional knockout of TOPK in keratinocytes suppressed neutrophils infiltration and attenuated psoriatic inflammation. Neutrophils deletion by neutralizing antibody greatly diminished the suppressive effect of TOPK cko in psoriasis-like dermatitis in mice. In addition, topical application of TOPK inhibitor OTS514 effectively attenuated already-established psoriasis-like dermatitis in mice. Mechanismly, RNA-seq revealed that TOPK regulated the expression of some genes in the IL-17 signaling pathway, such as neutrophils chemokines CXCL1, CXCL2, and CXCL8. TOPK modulated the expression of neutrophils chemokines via activating transcription factors STAT3 and NF-κB p65 in keratinocytes, thereby promoting neutrophils infiltration and psoriasis progression.ConclusionsThis study identified a crucial role of TOPK in psoriasis by regulating neutrophils infiltration, providing new insights into the pathogenesis of psoriasis.

IL-17A and TNF-α-induced Dectin-1 expression may promote keratinocyte proliferation in psoriatic lesions.

Psoriasis is a common skin disease with a high recurrence rate. Aberrant keratinocyte proliferation is a significant pathogenic characteristic of psoriatic lesions, and studies have revealed that the development of psoriasis is significantly influenced by pro-inflammatory cytokines, such as IL-17A and TNF-α. Biologics targeting these cytokines have been widely used in psoriasis treatment and achieve remarkable effects, however, the underlying mechanism of how IL-17A and TNF-α specifically regulate keratinocyte proliferation has not been fully elucidated. Dectin-1 is an essential membrane protein that is directly related to the immune microenvironment and the proliferation of multiple cell types. To elucidate how IL-17A and TNF-α may promote keratinocyte proliferation in psoriatic lesions and whether Dectin-1 is involved. The expression of Dectin-1 in keratinocytes from psoriatic lesions was detected by real-time PCR, western blot and immunofluorescence. Correlation analysis and cytological experiments were then performed to determine the relationship between Dectin-1 and IL-17A/TNF-α in psoriatic lesions. Finally, we investigated the signalling pathway through which Dectin-1 may promote keratinocyte proliferation. Dectin-1 was significantly increased in keratinocytes from psoriatic lesions. Moreover, IL-17A and TNF-α effectively induced the expression of Dectin-1 in HaCaT cells, which was shown to activate the Syk/NF-κB signalling pathway and promote the proliferation of keratinocytes. IL-17A and TNF-α may promote the proliferation of keratinocytes in psoriatic lesions through induction of Dectin-1, indicating that Dectin-1 could be a potential therapeutic target for the treatment of psoriasis.

Expression and Function of VEGFRs in Normal Epidermis and Psoriatic Lesional Keratinocytes.

The study aimed to explore the expression and function of VEGFRs in normal epidermis and keratinocytes of psoriatic lesions. In this study, the expression and role of VEGFRs in keratinocytes were examined using examples from psoriatic and healthy individuals. The experiment was completed by immunofluorescence analysis, reverse transcription polymerase chain reaction, Western blot, and real-time quantitative RT-PCR after the skin of nonlesional, adjacent, and lesional skin was excised. Observations indicated that in non-lesional psoriatic areas and adjacent lesional areas of the skin of psoriasis patients, the fluorescent signals of VEGFR-1 and VEGFR-2 were strongly labelled with keratinocytes, and in psoriatic lesions, keratinocytes were present throughout the entire thickness of the epidermis, with the exception of the stratum corneum. The distribution of VEGFR-3 in psoriatic nonlesional and adjacent lesional skin was consistent with that in normal epidermis, whereas all layers of the epidermis of psoriatic lesions expressed VEGFR-3. The mRNA expression levels of VEGFR-1,2,3 steadily increased from the normal epidermis to the psoriatic nonlesional, adjacent lesional, and perilesional areas, with the lesional epidermis' keratinocytes exhibiting the greatest levels of mRNA expression. Ca ions upregulate VEGFR-1,2,3 mRNA and protein expression in keratinocytes of nonlesional areas of psoriasis. VEGFRs protein expression and cortical IOD values of psoriatic and normal population cells showed a positive correlation. Hence, in comparison to normal epidermal keratinocytes, psoriatic lesional regions' keratinocytes considerably enhanced their expression of VEGFR-1,2,3 mRNA and protein. The overexpression of VEGFR-1,2,3 in psoriatic lesions may be encouraged by VEGF and Ca þ ions.

Tumor-Derived PD-L1+ Exosomes with Natural Inflammation Tropism for Psoriasis-Targeted Treatment.

Psoriasis is a chronic inflammatory disease whose etiology is directly related to the dysregulation of cutaneous immune homeostasis. However, how to finely modulate the skin immune microenvironment to restore homeostasis remains an important challenge. Inspired by the natural attribute of tumor exosomes in the immune escape, the tumor-derived exosomes as an active targeting nanoplatform for the effective treatment of inflammatory skin disorder were first reported. As keratinocytes and immune cells express high PD-1 during the onset of psoriasiform skin inflammation, the PD-L1-positive exosomes derived from melanoma cells carrying pristimerin with extremely anti-inflammatory potential were yielded to treat psoriasis. The PD-L1+ exosomes carrying pristimerin were characterized, and the cellular uptake was performed to evaluate the PD-1 target capability. The anti-inflammatory action of PD-L1+ exosomes carrying pristimerin was observed in both in vitro and in vivo models of psoriasis. Our exosomes substantially increased pristimerin uptake with CD4+ T cells and keratinocytes, significantly inhibited the proliferation of Th17 cells, and promoted Treg differentiation in a psoriasis-like model. Obviously, PD-L1+ exosomes carrying pristimerin significantly and safely reversed imiquimod (IMQ)-induced psoriasis in mice, indicated by reducing epidermal thickness, decreasing plaque formation, and suppressed excessive inflammatory response, due to its dual targeting of both CD4+ T cells and keratinocytes gathering around the lesion. The inflammatory cell infiltration and pro-inflammatory cytokine production in psoriasis were suppressed by our engineered exosomes. Besides, PD-L1+ exosomes carrying pristimerin treatment alleviated ferroptosis-related changes in psoriatic skin, thereby dampening excessive inflammation and, in turn, decreasing the abnormal proliferation of keratinocytes in psoriatic lesions. This study demonstrates that our engineered exosomes can not only act as a treat-to-target strategy for psoriasis treatment but also provide insight in clinical application of inflammatory disorders.

Advanced Glycation End Products-Induced Activation of Keratinocytes: A Mechanism Underlying Cutaneous Immune Response in Psoriasis

Psoriasis is a common inflammatory skin disease, in which epidermal keratinocytes play a vital role in its pathogenesis by acting both as the responder and as the accelerator to the cutaneous psoriatic immune response. Advanced glycation end products (AGEs) are a class of proinflammatory metabolites that are commonly accumulating in cardiometabolic disorders. Recent studies have also observed the increased level of AGEs in the serum and skin of psoriasis patients, but the role of AGEs in psoriatic inflammation has not been well investigated. In the present study, we initially detected abnormal accumulation of AGEs in epidermal keratinocytes of psoriatic lesions collected from psoriasis patients. Furthermore, AGEs promoted the proliferation of keratinocytes via upregulated Keratin 17 (K17)-mediated p27KIP1 inhibition followed by accelerated cell cycle progression. More importantly, AGEs facilitated the production of interleukin-36 alpha (IL-36α) in keratinocytes, which could enhance T helper 17 (Th17) immune response. In addition, the induction of both K17 and IL-36α by AGEs in keratinocytes was dependent on the activation of signal transducer and activator of transcription 1/3 (STAT1/3) signaling pathways. At last, the effects of AGEs on keratinocytes were mediated by the receptor for AGEs (RAGE). Taken together, these findings support that AGEs potentiate the innate immune function of keratinocytes, which contributes to the formation of psoriatic inflammation. Our study implicates AGEs as a potential pathogenic link between psoriasis and cardiometabolic comorbidities.

118 Downregulation of PAD1 in lesional psoriatic keratinocytes is driven by inflammatory cytokines

Protein post-translational modifications form a vital component of inflammatory microenvironment and are critical in the pathogenesis of multiple skin disorders. One among them is protein deimination or citrullination, catalyzed by peptidyl-arginine deiminases (PADs). Expression of these enzymes in tightly controlled during differentiation of keratinocytes, however the regulatory elements are still unknown. Here we show that the cytokines infiltrating skin during inflammation, regulate expression of PADs.

To act or not to act

Background: Psoriasis is a chronic, immune-mediated and angiogenesis-dependent disease. Activated keratinocytes in psoriatic lesions produce pro-angiogenic cytokines, including vascular endothelial growth factor (VEGF), which binds to vascular endothelial growth factor receptor (VEGFR) and promotes cell proliferation and angiogenesis. Sorafenib (BAY 43-9006) is a molecular multikinase inhibitor of RAF kinase, platelet-derived growth factor (PDGF), VEGFR-1, -2, -3, platelet-derived growth factor receptor (PDGFR)-β and c-Kit. This molecule inhibits tumor cell proliferation and angiogenesis and it is currently approved for the treatment of hepatocellular carcinoma (HCC). Case Report: We present the complete remission of resistant psoriasis in a hepatitis C virus (HCV)-infected cirrhotic patient who was treated with sorafenib, for recurrent HCC. Conclusion: Several targeted therapies have demonstrated efficacy against psoriasis. More research and well-designed studies, both in novel drugs and those already marketed for other indications, are needed to determine their value as potential novel therapies for psoriasis.

Effect of RNA Interference Targeting STAT3 Gene Combined with Ultrasonic Irradiation and SonoVue Microbubbles on Proliferation and Apoptosis in Keratinocytes of Psoriatic Lesions.

Background:Signal transducer and activator of transcription 3 (STAT3) was strongly expressed and activated in psoriatic keratinocytes (KCs) and correlated with the severity of psoriasis. The study aimed to investigate the effects of STAT3 small interfering RNA (siRNA) combined with ultrasonic irradiation and SonoVue microbubbles on the proliferation and apoptosis in KCs of psoriatic lesions and the relative mechanisms.Methods:Psoriatic KCs were transfected under four experimental conditions: (1) STAT3 siRNA carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (LUS group); (2) STAT3 siRNA only carried by Lipofectamine 3000 (L group); (3) the negative control of siRNA carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (siRNA-NC); (4) not treated as Blank. Cell Counting Kit-8 assay was used to evaluate the cell proliferation. Cell cycle analysis was detected with cycle test Plus DNA reagent kit associated with flow cytometer. FITC Annexin V apoptosis detection kit associated with flow cytometer was applied for apoptosis analysis. Fluo calcium indicator associated with flow cytometer was used to analyze intracellular free calcium concentration ([Ca2+]i). The expressions of cyclin D1 and Bcl-xL were detected both at the mRNA level by real-time reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by Western blotting. The obtained data were statistically evaluated by two-way analysis of variance.Results:STAT3 siRNA inhibited the growth of KCs in a time-dependent manner showing the highest proliferation inhibition in LUS group with proliferation ratio of 45.38% ± 5.85% at 72h (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced an altered cell cycle distribution of KCs showing the highest increases in G2/M-phase population up to 18.06% ± 0.36% in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced late apoptosis of KCs with the highest late apoptosis percentage of 22.87% ± 1.28% in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced the elevation of [Ca2+]i of KCs with the highest calcium fluorescence intensity mean of 1213.67 ± 60.51 in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced the downregulation of cyclin D1 and Bcl-xL expressions of KCs at mRNA and protein levels with the lowest expressions in LUS group with cyclin D1 expression of 51.81% ± 9.58% and 70.17% ± 4.22% at mRNA level and at protein level, respectively, and with Bcl-xL expression of 37.58% ± 4.92% and 64.06% ± 7.78% at mRNA level and at protein level, respectively (P < 0.05 vs. L group, siRNA-NC, or Blank).Conclusions:STAT3 siRNA inhibited the growth and induced the apoptosis in psoriatic KCs likely partly through altering cell cycle distribution, elevating [Ca2+]i, and downregulating cyclin D1 and Bcl-xL expressions. Silencing the target gene STAT3 in psoriatic KCs with siRNA combined with ultrasonic irradiation and microbubbles would contribute to a significant innovation as a new clinical therapy for psoriasis.

Epigenetic control of IL-23 expression in keratinocytes is important for chronic skin inflammation

The chronic skin inflammation psoriasis is crucially dependent on the IL-23/IL-17 cytokine axis. Although IL-23 is expressed by psoriatic keratinocytes and immune cells, only the immune cell-derived IL-23 is believed to be disease relevant. Here we use a genetic mouse model to show that keratinocyte-produced IL-23 is sufficient to cause a chronic skin inflammation with an IL-17 profile. Furthermore, we reveal a cell-autonomous nuclear function for the actin polymerizing molecule N-WASP, which controls IL-23 expression in keratinocytes by regulating the degradation of the histone methyltransferases G9a and GLP, and H3K9 dimethylation of the IL-23 promoter. This mechanism mediates the induction of IL-23 by TNF, a known inducer of IL-23 in psoriasis. Finally, in keratinocytes of psoriatic lesions a decrease in H3K9 dimethylation correlates with increased IL-23 expression, suggesting relevance for disease. Taken together, our data describe a molecular pathway where epigenetic regulation of keratinocytes can contribute to chronic skin inflammation.

Effects of RNA interference combined with ultrasonic irradiation and SonoVue microbubbles on expression of STAT3 gene in keratinocytes of psoriatic lesions.

The most effective sequence of small interfering RNA (siRNA) silencing STAT3 of psoriatic keratinocytes (KCs) was screened out, and the effects of the most effective siRNA combined with ultrasonic irradiation and SonoVue microbubbles on the expression of STAT3 of KCs and the dose- and time-response were investigated. Three chemically-synthetic siRNAs targeting STAT3 carried by Lipofectamine 3000 were transfected into KCs, and the effects on STAT3 expression were detected, then the most effective siRNA was selected for the subsequent experiments. The negative controls of siRNA (siRNA-NC) labeled with Cy3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles were transfected into KCs, then the optimal parameters of ultrasonic irradiation were determined. The most effective siRNA carried by Li-pofectamine 3000 combined with ultrasonic irradiation at the optimal parameters and SonoVue microbubbles was transfected into KCs, and the dose- and time-response of RNA interference was determined. The effect of RNA interference by the most effective siRNA at the optimal time and dose carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (LUS group) was compared with that only carried by Li-pofectamine 3000 (L group). The results showed that siRNA-3 achieved the highest silencing efficacy. 0.5 W/cm2 and 30 s were selected as the parameters of ultrasonic irradiation. The siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles could effectively knock down the STAT3 expression at mRNA and protein levels in dose- and time-dependent manners determined at 100 nmol/L with maximum downregulation on mRNA at 48 h, and on protein at 72 h after transfection. The LUS group achieved the highest silencing efficacy. It was concluded that siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles could effectively knock down the STAT3 expression in psoriatic KCs, and the optimized transfection condition and the sequence of siRNA-3 could serve for further research on gene therapy of psoriasis.

Significance of vascular endothelial growth factor and CD31 and morphometric analysis of microvessel density by CD31 receptor expression as an adjuvant tool in diagnosis of psoriatic lesions of skin.

Pathogenesis of psoriasis is a debated issue. Several mechanisms have been proposed to identify the etiology and pathogenesis so that specific treatments can be given to patients with psoriasis. (1) To compare pattern and distribution of vascular endothelial growth factor (VEGF) and CD31 in patients with psoriasis and other psoriasiform lesions of skin. (2) To study the correlation between VEGF and CD31 expression, clinical severity, and histopathology of psoriasiform lesions of skin. (3) Evaluation of microvessel density (MVD) by using computer-assisted quantitative image analysis in psoriatic skin lesions. This study was conducted on eighty cases, out of which forty were diagnosed cases of psoriasis and forty cases of clinically suspected psoriasiform lesions, submitted in the Department of Pathology, Pt. B.D. Sharma, University of Health Sciences, Rohtak, for histopathological examination. Histopathological sections were stained by routine hematoxylin and eosin staining, and these biopsies were further subjected to immunohistochemical staining with VEGF and CD31 as per standard technique. Assessment of various histopathological features revealed strong correlation between epidermal hyperplasia, suprapapillary thinning, and elongation of rete ridges. Suprabasilar keratinocytes in psoriatic lesions stained intensely for VEGF. The difference for number of microvessels and MVD in psoriasis and psoriasiform lesions was statistically significant. Correlation between intensity of VEGF staining by suprabasilar keratinocytes and MVD was found to be highly significant in psoriatic lesions. The present study concluded that psoriatic lesions exhibit potent angiogenic activity. Early lesions show increased MVD along with other histomorphological parameters such as hypogranulosis, parakeratosis and Munro's microabscesses. Overexpression of VEGF by suprabasilar keratinocytes correlated with increased MVD in papillary dermis.

Effects of adalimumab, etanercept and ustekinumab on the expression of psoriasin (S100A7) in psoriatic skin

BackgroundPsoriasis is a chronic inflammatory skin disease. It is characterized by immune cell activation and altered epidermal differentiation. S100A7 (psoriasin) is overexpressed in psoriasis, suggesting a determinant role of this protein in inflammation and keratinocyte differentiation. ObjectiveThe purpose of this study was to investigate the expression of S100A7 in the skin from psoriatic patients undergoing biological therapy with adalimumab, etanercept or ustekinumab. MethodsS100A7 expression and distribution were analyzed by immunohistochemistry. ResultsS100A7, overexpressed in epidermal keratinocytes of psoriatic lesions, was downregulated, under the biological therapy with adalimumab, etanercept or ustekinumab, only in patients achieving a PASI score<15. ConclusionsDysregulation of S100A7 may represent a non-negligible player in the maintenance of psoriasis and the relative epidermal changes. Blockage of S100A7 may represent an additional therapeutic approach in the treatment of psoriasis.

Expression of peroxisome proliferator-activated receptor β/δ in psoriatic epidermal keratinocytes

Objective To measure the expression of peroxisome proliferator-activated receptor β/δ (PPARβ/δ) in epidermal keratinocytes from patients with psoriasis,and to investigate its regulatory factors.Methods Tissue specimens were obtained from both lesional and non-lesional skin of 20 patients with psoriasis as well as from normal skin of 15 human controls.An immunohistochemical method was used to examine the expression of PPARβ/δ in these tissue specimens.Epidermal keratinocytes were isolated from these tissue specimens and subjected to a primary culture.After several passages of subculture,non-lesional psoriatic keratinocytes were stimulated with different concentrations of GW501516 (an agonist of PPARβ/δ,0-100 ng/ml) and Ca2+ (0-3.0 mmol/L).Reverse transcription-PCR and Western blot were performed to measure the mRNA and protein expressions of PPARβ/δ in the primary keratinocytes and stimulated keratinocytes respectively.Results Immunohistochemistry showed that the expression intensity of PPARβ/δ was significantly higher in lesional psoriatic skin than in normal control skin (t =19.28,P ＜ 0.01) and non-lesional psoriatic skin (t =23.26,P ＜ 0.01).Increased mRNA and protein levels of PPARβ/δ were observed in lesional psoriatic keratinocytes as compared to normal control keratinocytes (both P ＜0.01) and non-lesional psoriatic keratinocytes (both P ＜ 0.01).Among these stimulated non-lesional psoriatic keratinocytes,those treated with GW501516 at 10 ng/ml and those with Ca2+ of 1.0 mmol/L showed the strongest expression of PPARβ/δ (both P ＜ 0.01).Conclusions The expression of PPARβ/δ,which is higher in lesional psoriatic skin,can be enhanced by GW501516 and Ca2+ in keratinocytes. Key words: Psoriasis; Keratinocytes; PPARβ/δ

Role of vascular endothelial growth factor, survivin, and inducible nitric oxide synthase expression in psoriasis: an immunohistochemical study

Background Psoriasis (PS) is a common chronic, relapsing, immune-mediated disease involving the skin and joints of genetically predisposing individuals. Despite numerous studies, the pathogenesis of PS has not been fully elucidated. However, many pathogenic theories have been suggested. There is much evidence that PS is a polygenic disease modified to expression by triggering factors. PS is characterized by hyperproliferation and abnormal differentiation of epidermal keratinocytes, lymphocyte infiltration consisting mostly of T lymphocytes, and various endothelial vascular changes in the dermal layer, such as angiogenesis, dilation, and high endothelial venule formation. Vascular endothelial growth factor (VEGF) is a major regulator of physiological and pathological angiogenesis, causing aberrant angiogenesis and vascular leakage in the upper dermis; it may also contribute to keratinocyte proliferation and epidermal barrier homeostasis in PS. Inducible nitric oxide synthase (iNOS) was found to be expressed in the keratinocytes of psoriatic lesions; in addition, there is increased expression of iNOS-specific mRNA transcripts. Survivin upregulation in psoriatic lesion in comparison with normal skin was evident, suggesting its role in the pathogenesis of PS. The aim of this study was to investigate the immunohistochemical expression of VEGF, survivin, and iNOS in psoriatic skin and to detect their role in the pathogenesis of PS. Patients and methods This study was carried out on 20 patients with PS vulgaris. Immunohistochemical reactions were carried out using the streptavidin-biotin immunoperoxidase system in this study to detect the extent of expression of VEGF, survivin, and iNOS in each specimen of the skin biopsy. Results A strong VEGF expression through the epidermis (mean 46.4 ΁ 19.7) was observed. VEGF was significantly upregulated in psoriatic skin in comparison with normal healthy skin ( P P P Conclusion VEGF, survivin, and iNOS appeared to be important factors in the pathogenesis of PS.

Keratin 17: A Critical Player in the Pathogenesis of Psoriasis

Keratin 17 (K17) is an intermediate filament protein present in the basal cells of complex epithelia, such as nails, hair follicles, sebaceous glands, and eccrine sweat glands. Studies have shown that it is expressed aberrantly in the suprabasal keratinocytes of psoriatic lesions, compared to in normal epidermis. K17 is also closely associated with the immune system and plays an important role in the pathogenesis of psoriasis. In this review, we present our experimental findings concerning the role of K17 in psoriasis, and compare them to results published in the literature. Our results show that cytokines related to Th17 and IL-22-producing (where Th17 is T helper cells, type 17 and IL is interleukin) CD4(+) T cells, including IL-17A and IL-22, upregulate the expression of K17 in keratinocytes. In addition, K17 stimulates autoreactive T cells and promotes the production of psoriasis-associated cytokines. Our findings lend support to the hypothesis that a K17/T-cell/cytokine autoimmune loop is involved in the pathogenesis of psoriasis. We therefore review the current understanding of the K17 immunoregulation, including its expression and direct/indirect effects on immune responses. Pertinent strategies for the treatment of psoriasis are also discussed.

IL-17 gene transfer in vivo induces bone loss and epidermal hyperplasia with implications for psoriatic arthritis (P3377)

Abstract The IL-23/IL-17 axis has been linked with pathologic features of psoriatic arthritis, however the direct role of IL-17 on innate immune cells has not been fully elucidated. We have previously demonstrated that IL-17 in vitro contributes to arthritis pathogenesis by inducing osteoclast differentiation and bone resorption. To validate these findings we overexpressed IL-17A in vivo by combining mini-circle DNA technology with hydrodynamic delivery and performed phenotypic analysis of cell populations by FACS, qPCR, histology and in vivo imaging using nanoprobes. We identified that IL-17 induced two distinct IL-17R+ populations, CD11b+Gr1low and CD11b+Gr1high that differentially contribute to bone erosion and epidermal hyperplasia respectively. Our data show that systemic high levels of IL-17 in the serum induce RANK+/c-fms+ osteoclast precursors within the CD11b+Gr1low fraction. To address the functional importance of these precursors we performed RANKL gene transfer to IL-17 overexpressing mice and noticed a significant increase of serum TRAP that correlated with increased bone erosion by microCT. Accordingly, the increase in the CD11b+Gr1high population correlated with an induction of epidermal hyperplasia, Munro’s microabscesses and hyperproliferative keratinocytes in psoriatic lesions. Collectively our data demonstrate mechanistically the role of innate immune precursor cells in the contribution to bone loss and epidermal hyperplasia, hallmarks of PsA.

Possible roles of barrier-to-autointegration factor 1 in regulation of keratinocyte differentiation and proliferation

BackgroundBarrier-to-autointegration factor 1 (BANF1) is an essential component of the nuclear lamina. Recent studies have clarified that BANF1 is a causative molecule of Nestor-Guillermo progeria syndrome. Despite recent progress in studies on BANF1, the role of BANF1 in keratinocytes has not been addressed at all. ObjectiveThis study aims to determine the localization of BANF1 in psoriatic epidermal keratinocytes as well as in normal keratinocytes and to clarify its possible function in those keratinocytes. MethodsImmunohistochemistry of BANF1 was performed on 10 cases of psoriasis and 10 healthy control individuals. Expression of molecules associated with inflammation of the skin by HSC-1, a human skin squamous cell carcinoma cell line, stimulated by TPA and treated with siRNA to BANF1 were analyzed with quantitative PCR and Western blot. ResultsStrong nuclear-dominant immunostaining of BANF1 was seen in the epidermal keratinocytes of psoriatic lesions, although in the normal epidermis, all the KCs in the upper epidermis showed cytoplasmic-dominant staining of BANF1. By BANF1 knockdown in TPA-stimulated HSC-1 cells, the mRNA levels of S100A9 were significantly elevated compared with those of control HSC-1 cells treated with siRNA to CD4. The protein expression level of S100A9 and phosphorylated c-Jun was elevated by BANF1 knockdown. ConclusionBANF1 is translocated onto the nuclear envelope in the psoriatic epidermal keratinocytes, suggesting that BANF1 is associated with upregulated proliferation of keratinocytes in psoriatic lesions. Activation of BANF1 possibly suppresses S100A9 expression and inactivates c-Jun, resulting in suppression of cutaneous inflammation.

S100A8 and S100A9 are messengers in the crosstalk between epidermis and dermis modulating a psoriatic milieu in human skin

S100A8 and S100A9 are members of the S100A8 protein family that exist as homodimers and heterodimers in neutrophils, monocytes, and macrophages. Recent studies have shown the pivotal roles of S100A8 and S100A9 in the propagation of inflammation and keratinocyte proliferation in psoriasis. We found significant up-regulation of S100A8 and S100A9 secretion from keratinocytes in psoriatic lesions. To mimic the in vivo secretory conditions of S100A8 and S100A9 from psoriatic epidermal keratinocytes, we used the culture medium (CM) of S100A8 and S100A8/A9 adenovirus-transduced keratinocytes to investigate the functions of S100A8 and S100A9. We detected increased levels of various pro-inflammatory cytokines in the CM, including IL-8 and TNF-α, which are involved in aggravating psoriatic skin lesions, and IL-6 and members of the CXCL family of pro-angiogenic cytokines. The CM increased immune cell migration and increased angiogenesis in human umbilical vein endothelial cells. In conclusion, we found that the upregulated production of S100A8 and S100A9 by psoriatic epidermal keratinocytes activated adjacent keratinocytes to produce several cytokines. Moreover, S100A8 and S100A9 themselves function as pro-angiogenic and chemotactic factors, generating a psoriatic milieu in skin.

Cathelicidin Antimicrobial Peptide LL-37 in Psoriasis Enables Keratinocyte Reactivity against TLR9 Ligands

Here we show that keratinocytes in psoriatic lesional skin express increased Toll-like receptor (TLR) 9 that similarly localizes with elevated expression of the cathelicidin antimicrobial peptide LL-37. In culture, normal human keratinocytes exposed to LL-37 increased TLR9 expression. Furthermore, when keratinocytes were exposed to LL-37 and subsequently treated with TLR9 ligands such as CpG or genomic DNA, keratinocytes greatly increased production of type I interferons. This response mimicked observations in the epidermis of psoriatic lesional skin as keratinocytes in psoriatic lesions produce greater amounts of interferon-β than normal skin lacking LL-37. The mechanism for induction of type I interferons in keratinocytes was dependent on TLR9 expression but not on a DNA-LL-37 complex. These findings suggest that keratinocytes recognize and respond to DNA and can actively participate in contributing to the immunological environment that characterizes psoriasis.

Expression of peroxisome proliferator-activated receptors in the epidermis of skin from patients with psoriasis vulgaris

Objective To investigate the expression of peroxisome proliferator-activated receptors (PPARs) in epidermal keratinocytes of patients with psoriasis vulgaris and its significance.Methods Immunohistochemical method was used to examine the expression of PPARα,β/δand.γ in tissue specimens from the normal skin of 5 human controls,lesional and normal skin adjacent to the lesions of 17 patients with psoriasis vulgaris.A semi-quantitative analysis was carried out by image analyzer.Results Different levels of expression of the three PPAR isotypes were observed in the nuclei of epidermal keratinocytes of normal human controls.The expression intensity of PPAR α,β/δand γ was statistically higher in the epidermis of adjacent normal skin than that in psoriatic lesions(all P<0.01)and normal control skin(all P<0.01).Conclusions The decreased expression of PPARα may be associated with the overproliferation and parakeratosis of epidermal keratinocytes in psoriatic lesions,and PPAR β/δ and γ may display a synergistic effect on the maintenance of homeostatic proliferation and difierentiafion of epidermal cells.