Increased CCL18 expression in patients with cutaneous T‐cell lymphoma: association with disease severity and prognosis

Background CC chemokine ligand (CCL) 18 is expressed by monocytes and dendritic cells (DCs), and has potent chemotactic activity for T cells, B cells and DCs. CCL18 expression is up‐regulated in lesional skin of atopic dermatitis and bullous pemphigoid, suggesting its important roles in the development of these skin diseases. Objective To investigate roles of CCL18 in cutaneous T‐cell lymphoma (CTCL). Methods The CCL18 messenger RNA (mRNA) expression in CTCL skin (n = 21) and in normal skin (n = 7) was examined by quantitative RT‐PCR. CCL18 expression was also examined by immunohistochemistry. Serum CCL18 levels were measured in 38 patients with CTCL and 20 healthy controls by enzyme‐linked immunosorbent assay. We also analysed correlation between serum CCL18 levels and other clinical and laboratory data. Results The CTCL lesional skin contained higher levels of CCL18 mRNA than normal skin. CCL18 was expressed by dermal macrophages and DCs in CTCL skin. Serum CCL18 levels in patients with CTCL were significantly higher than those of healthy controls and correlated with types of skin lesions. They also significantly correlated with modified severity‐weighted assessment scores, serum sIL‐2R, LDH, IL‐4, IL‐10, IL‐31, CCL17 and CCL26 levels. Patients with high serum levels of CCL18 showed significantly poor prognosis compared with those with low CCL18 levels. Conclusion CCL18 mRNA is up‐regulated in CTCL lesional skin, and serum CCL18 levels are significantly increased and correlated with the severity of CTCL. These results suggest that CCL18 may be associated with the development of CTCL.     

CCL7 contributes to the TNF‐alpha‐dependent inflammation of lesional psoriatic skin

Chemokines are small chemotactic proteins that have a crucial role in leukocyte recruitment into tissue. Targeting these mediators has been suggested as a potential therapeutic option in inflammatory skin diseases such as psoriasis. Using quantitative RT‐PCR, we found CCL7, a chemokine ligand known to interact with multiple C‐C chemokine receptors, to be markedly increased in lesional psoriasis as opposed to atopic dermatitis, lichen planus, non‐lesional psoriatic and normal control skin. Surprisingly, this increase in CCL7 mRNA expression exceeded that of all other chemokines investigated, and keratinocytes and dermal blood endothelial cells were identified as its likely cellular sources. In an imiquimod‐induced psoriasis‐like mouse model, CCL7 had a profound impact on myeloid cell inflammation as well as on the upregulation of key pro‐psoriatic cytokines such as CCL20, IL‐12p40 and IL‐17C, while its blockade led to an increase in the antipsoriatic cytokine IL‐4. In humans receiving the TNF‐α‐blocker infliximab, CCL7 was downregulated in lesional psoriatic skin already within 16 hours after a single intravenous infusion. These data suggest that CCL7 acts as a driver of TNF‐α‐dependent Th1/Th17‐mediated inflammation in lesional psoriatic skin.     

Expression of CCL1 and CCL18 in atopic dermatitis and psoriasis

Background.  Recent studies have shown that chemoattractive proteins play an important role in the organization of the innate and adaptive immune responses. There are some reports that chemokine (C‐C motif) ligand (CCL)1 and CCL18, members of a family of chemoattractive proteins, have increased expression in atopic dermatitis (AD). Aim.  To evaluate the quantity and pattern of CCL1 and CCL18 expression in lesions and blood of patients with AD, and compare them with those of patients with psoriasis. Methods.  Biopsy specimens were taken from atopic skin and normal‐appearing skin of patients with AD and from the psoriatic skin only of patients with psoriasis. Quantitative real‐time PCR analysis and immunohistochemistry of CCL1 and CCL18 expression were performed, and the quantities of expressed CCL1 and CCL18 in acute AD were compared with those of normal‐appearing atopic skin and psoriatic skin. The serum level of CCL1 and CCL18 was assessed by ELISA. Results.  Expression of CCL1 mRNA and protein was significantly higher in the acute lesional skin of patients with AD than in their nonlesional skin or in the lesional skin of patients with psoriasis. Both CCL18 mRNA and protein were abundant in acute AD lesions and in psoriatic lesions, but were lower in the nonlesional skin of patients with AD. The serum levels of CCL1 and CCL18 were not different in patients with AD and patients with psoriasis. Conclusions.  CCL1 is a chemokine that is associated with AD. Both CCL1 and CCL18 may play important roles in the initiation and progression of atopic skin inflammation.     

Oxytocin modulates proliferation and stress responses of human skin cells: implications for atopic dermatitis

The neuropeptide hormone oxytocin (OXT) mediates a wide spectrum of tissue‐specific actions, ranging from cell growth, cell differentiation, sodium excretion to stress responses, reproduction and complex social behaviour. Recently, OXT expression was detected in keratinocytes, but expression of its receptor and function are still unexplored in human skin. Here, we showed that both OXT and its receptor are expressed in primary human dermal fibroblasts and keratinocytes. OXT‐induced dose‐dependent calcium fluxes in both cell types demonstrating that the OXT receptor (OXTR) is functionally expressed. We also showed that OXT decreases proliferation of dermal fibroblasts and keratinocytes in a dose‐dependent manner. In order to further investigate OXT‐mediated functions in skin cells, we performed OXTR knockdown experiments. OXTR knockdown in dermal fibroblasts and keratinocytes led to elevated levels of reactive oxygen species and reduced levels of glutathione (GSH). Moreover, OXTR‐depleted keratinocytes exhibited an increased release of the pro‐inflammatory cytokines IL6, CCL5 and CXCL10. Our data indicate that the OXT system modulates key processes which are dysregulated in atopic dermatitis (AD) such as proliferation, inflammation and oxidative stress responses. Furthermore, we detected a downregulation of the OXT system in peri‐lesional and lesional atopic skin. Taken together, these data suggest that the OXT system is a novel neuroendocrine mediator in human skin homoeostasis and clinically relevant to stressed skin conditions like AD.     

Kinetics and differential expression of the skin-related chemokines CCL27 and CCL17 in psoriasis, atopic dermatitis and allergic contact dermatitis

CCL27 and CCL17 are chemokines believed to be involved in the process of establishing the inflammatory infiltrate, characteristic for the various inflammatory skin diseases. The skin-specific CCL27 binds the chemokine receptor-10 (CCR10), and CCL17 is a chemokine receptor-4 (CCR4) ligand. The purpose of our study was to characterize the expression of CCL27 and CCL17 in the inflammatory skin diseases: psoriasis, atopic dermatitis (AD) and acute allergic contact dermatitis (ACD) induced in nickel-sensitive individuals. Surprisingly, our studies revealed a markedly decreased CCL27 mRNA and protein expression in psoriatic lesions compared with non-lesional psoriatic skin. A minor CCL17 mRNA increase was measured in lesional psoriatic skin. No alterations were found in AD. In ACD, we found a pronounced (90-fold) raise in CCL17 mRNA and a 50-fold increase in CCL17 protein compared with normal skin. A kinetic ACD study of CCL17 expression showed the highest mean value 24 h after hapten application. Furthermore, we found the mRNA levels of CCR10 and CCR4 paralleling the results of their corresponding ligands. Overall, our principal findings were a distinct decrease in CCL27 in lesional psoriatic skin and a marked upregulation of CCL17 in ACD. These findings underscore the differential cutaneous T-cell recruitment in different inflammatory diseases.     

Expression of Fc receptors for IgG during acute and chronic cutaneous inflammation in atopic dermatitis

Atopic dermatitis is an allergic skin disease characterized by elevated total and antigen-specific serum IgE and IgG4 levels. In acute and chronic cutaneous inflammation, large cellular infiltrates including T cells, dendritic cells and macrophages are found, especially in the dermis. These cells play an important part in the regulation of local inflammatory reactions. Receptors binding IgG (FcgammaR) are involved in dendritic cell and macrophage function. In this study, we examined the in vivo distribution and cellular expression of the three classes of leucocyte FcgammaR in human skin during acute and chronic cutaneous inflammation in atopic dermatitis. Atopy patch test skin was used as a model for acute inflammation in atopic dermatitis, while chronic lesional skin was used to investigate FcgammaR expression in chronically inflamed skin. In atopy patch test sites no increase in the number of CD1a+ dendritic cells and a slight increase in macrophages compared with non-lesional skin was observed. Our results showed increased expression of FcgammaRI (CD64) and FcgammaRIII (CD16) in acutely inflamed skin as well as in chronically inflamed lesional skin, compared with healthy and non-lesional atopic dermatitis skin. FcgammaRI was expressed by RFD1+, RFD7+ and CD68+, but not by CD1a+ dermal dendritic cells. RFD1+ dendritic cells and CD68+ macrophages were the main FcgammaRIII-expressing cells during the acute inflammatory reaction. The significant increase in expression of FcgammaRIII (CD16) and FcgammaRI (CD64) probably results from upregulation of the receptors on resident cells. Insight into the presence of FcgammaR+ cells in human skin during inflammation is important both for our understanding of skin immune reactions and the development of new therapeutic concepts.     

The effect of pimecrolimus on expression of genes associated with skin barrier dysfunction in atopic dermatitis skin lesions

Abstract: The mechanism of action of pimecrolimus (PIM) on atopic lesions is still under consideration. Thus far, we have evidence of its anti‐inflammatory and immunomodulatory activity, and recent papers focus on its effect on epidermal barrier function. This study analysed changes in the expression of genes associated with skin barrier dysfunction in atopic dermatitis (AD) skin lesions after 2 weeks of exposure to PIM 1% cream. A real‐time quantitative PCR analysis of selected epidermal differentiation complex genes and three alternative pathway keratins was performed in skin biopsies from 11 individuals with AD before and after PIM exposure. The real‐time quantitative PCR analysis was compared to non‐lesional skin in the same patients. Involucrin, a small proline‐rich region (SPRR) 2C gene, and alternative pathway keratin 16 showed significant over‐expression in lesional skin followed by significant decrease after PIM therapy. The SPRR1A gene, S100A9, and keratin 6A were also increased; however, the decrease after PIM treatment was not significant. The changes in S100 A2, A7 and A8 followed a similar course with borderline significance. SPRR4 had a significant decrease in expression in lesional versus non‐lesional skin, which persisted after PIM treatment. No significant changes were detected in mRNA expression levels of filaggrin and loricrin. Our results suggest that PIM can be effective in restoring the epidermal barrier in patients with AD at least in part by its impact on expression of genes, which are important for the normal barrier function of skin.     

Enzymes involved in the conversion of arachidonic acid to eicosanoids in the skin of atopic dogs

Please cite this paper as: Enzymes involved in the conversion of arachidonic acid to eicosanoids in the skin of atopic dogs. Experimental Dermatology 2010; 19 : e317–e319. Abstract: Canine atopic dermatitis (AD), a chronic inflammatory skin disease, shares characteristics with its human counterpart. To get insight into the role of enzymes involved in production of prostaglandin E₂ (PGE2) and leukotriene B₄ (LTB₄), potent inflammatory mediators originating from membrane‐derived arachidonic acid (AA), expression of genes encoding these enzymes and receptors was quantified by qPCR in non‐lesional and lesional skin from atopic dogs and in healthy skin. Significantly higher mRNA expression of the key enzymes 5‐lipoxygenase (5‐LO), 5‐LO activating protein (FLAP), leukotriene A₄ hydrolase (LTA₄H) and prostaglandin E synthase 1 (mPGES‐1) and their receptors (PGE receptors 2 and 3) were observed. Being responsible for elevated levels of metabolites of the 3‐series prostaglandins and the 5‐series leukotrienes these enzymes may be interesting targets for therapy that should result in amelioration of clinical signs in canine atopic dermatitis.     

Fc epsilon R11/CD23 receptor distribution in patch test reactions to aeroallergens in atopic dermatitis.

There is increasing evidence that exposure to organic allergens may induce or exacerbate lesional skin in patients with atopic dermatitis. In this study, patients with atopic dermatitis were patch tested to 11 common organic allergens and to control chambers containing 0.4% phenol and 50% glycerin in 0.9% saline. In biopsies from positive patch test reactions, patch test control skin, lesional eczematous and non-lesional skin from atopic individuals, and normal skin from non-atopic volunteers, the presence and distribution of macrophages (RFD7+), dendritic cells (RFD1+), and Langerhans cells, and the expression of the low-affinity receptor for IgE (CD23) were investigated. In patch test reactions and lesional skin samples, inflammatory infiltrates of diffusely distributed macrophages (RFD7+), dendritic cells (RFD1+), T lymphocytes (RFTmix+), and Langerhans cells (CD1+) were seen, the latter being present in both the epidermis and the dermis. The numbers of Langerhans cells were reduced in the epidermis and increased in the dermis in patch test reactions and lesional skin compared to their controls. Double staining revealed a change in the distribution of CD23 antigen. In patch test control and non-lesional biopsies many macrophages and only a few Langerhans cells within the dermal infiltrates expressed this antigen. In patch test reaction and lesional skin samples, however, the proportion of CD23+ dermal Langerhans cells had increased compared to macrophages. Furthermore, in these latter samples an increased proportion of dermal CD1+ cells expressed the dendritic cell (RFD1+) marker. These results show that following antigen challenge there are marked similarities between the phenotype of the cellular infiltrate in patch test reaction and lesional skin biopsies, and also demonstrate a changing distribution of CD23 on antigen-presenting cells.     

Increased expression of the aryl hydrocarbon receptor in patients with chronic inflammatory skin diseases

Polychlorinated biphenyls (PCBs) and 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) are major environmental pollutants, and their effects on the human body critically depend on the aryl hydrocarbon receptor (AhR). The aim of this study was to evaluate the significance of the AhR and its ligands in chronic inflammatory skin diseases such as atopic dermatitis (AD) and psoriasis. Expression of AhR‐related mRNA was increased in lesional skin from patients with AD and psoriasis compared to those of normal skin from healthy controls. The AhR and aryl hydrocarbon receptor nuclear translocator were colocalized in the nuclei of keratinocytes at the lower epidermis of psoriatic lesions, which suggested activation of the AhR pathway. After treatment of normal human epidermal keratinocytes with TCDD or PCBs, IL‐6 and IL‐8 production were increased. The results of this study suggest that AhR is highly expressed in the acute lesional skin of patients with AD and psoriasis, and the AhR pathway is activated especially in psoriasis.     

Induction of eosinophil‐ and Th2‐attracting epidermal chemokines and cutaneous late‐phase reaction in tape‐stripped skin

Abstract: Skin barrier damage induces various harmful or even protective reactions in the skin, as represented by enhancement of keratinocyte cytokine production. To investigate whether acute removal of stratum corneum modulates the production of chemokines by epidermal cells, we treated ears of BALB/c and C57BL/6 mice by tape‐stripping, or acetone‐rubbing as a control of acute barrier disruption procedure. There was no difference between the tape‐stripped and acetone‐rubbed skin sites in the increased and recovered levels of transepidermal water loss. The mRNA expression levels of all the chemokines tested, including Th1 chemokines (CXCL10, CXCL9 and CXCL11), Th2 chemokines (CCL17 and CCL22) and eosinophil chemoattractant (CCL5), were higher in the epidermal cells from BALB/c than in those of C57BL/6 mice. In particular, CCL17, CCL22 and CCL5 were remarkably elevated in BALB/c mice and augmented by tape‐stripping more markedly than acetone‐rubbing, whereas Th1 chemokines were enhanced by acetone‐rubbing more remarkably. Tape‐stripping induced dermal infiltration of eosinophils in BALB/c but not C57BL/6 mice. In a contact hypersensitivity model, where BALB/c mice were sensitized on the abdomen and challenged on the ears with fluorescein isothiocyanate, mice exhibited higher ear swelling responses at the late‐phase as well as delayed‐type reactions, when challenged via the tape‐stripped skin. The challenge via tape‐stripped skin augmented the expression of IL‐4 and CCR4 in the skin homogenated samples, indicating infiltration of Th2 cells. These findings suggest that acute barrier removal induces the expression of Th2 and eosinophil chemokines by epidermal cells and easily evokes the late phase reaction upon challenge with antigen.     

Ultraviolet B radiation and reactive oxygen species modulate interleukin-31 expression in T lymphocytes, monocytes and dendritic cells

Background Interleukin (IL)‐31 is a novel Th2 T‐cell cytokine that induces pruritus and dermatitis in transgenic mice. While enhanced mRNA expression of this cytokine is detected in skin samples of inflammatory skin diseases, the regulation of IL‐31 expression is poorly understood. Objectives To assess the effects of ultraviolet (UV) B radiation and H₂O₂ on IL‐31 mRNA and protein expression in skin and different peripheral blood mononuclear cells (PBMCs). Methods The effects of UVB radiation and H₂O₂, as a prototypic reactive oxygen species, on IL‐31 mRNA and protein expression were analysed in various inflammation‐related cells and murine skin tissue. Results Treatment of cells with UVB radiation and H₂O₂ strongly induced IL‐31 mRNA and protein expression in human PBMCs and in the skin of SKH‐1 mice. Following exposure to UVB or H₂O₂, we observed increased expression of IL‐31 mRNA in T cells, monocytes, macrophages, and immature and especially mature dendritic cells. H₂O₂ treatment but not UVB radiation led to a moderate upregulation of IL‐31 mRNA expression in epidermal keratinocytes and dermal fibroblasts. Pretreatment of T lymphocytes with the MAPK p38 inhibitor SB203580 or the MEK1 inhibitor U0126 reduced the stimulatory effect of H₂O₂. These experiments suggest that p38 is involved in the regulation of IL‐31 expression in human skin. Conclusions Our studies reveal that UVB and reactive oxygen species stimulate the expression of IL‐31 in PBMCs and skin, especially in T cells, monocytes and monocyte‐derived dendritic cells.     

Injury downregulates the expression of the human cathelicidin protein hCAP18/LL‐37 in atopic dermatitis

Please cite this paper as: Injury downregulates the expression of the human cathelicidin protein hCAP18/LL‐37 in atopic dermatitis. Experimental Dermatology 2009; 19: 442–449. Abstract: Reduced production of antimicrobial peptides was proposed to contribute to susceptibility for skin infections in atopic dermatitis (AD). Focusing on the human cathelicidin protein, hCAP18, the aim of the present study was to explore whether reduced hCAP18 expression is a constitutive trait in AD and if established inducers affect the expression of hCAP18 in the skin of AD. First, we compared levels of hCAP18 mRNA between lesional skin in AD and psoriasis and verified significantly lower expression of hCAP18 mRNA in AD. In non‐lesional skin, however, there was no difference between AD, psoriasis and healthy, indicating that there is no constitutive defect in the production of hCAP18 in AD patients. In healthy skin, hCAP18 was reported to be rapidly induced following wounding and here we verified this pattern in healthy controls and in psoriasis. In AD lesions, however, the expression of hCAP18 mRNA was markedly suppressed following wounding. Obviously, the inflammation in AD lesions neutralizes the expected induction of hCAP18 and even induces suppression. Notably, the mechanism to upregulate hCAP18 following vitamin D treatment was functional in lesional as well as in non‐lesional AD indicating that the CAMP gene is normally regulated in this respect. In addition, cultured primary keratinocytes from non‐lesional skin of psoriasis, AD and healthy skin, upregulated hCAP18mRNA following treatment with vitamin D. Itching is a hallmark of AD and scratching inevitably injures the skin. Failure to upregulate hCAP18 in eczema following injury is likely to affect antimicrobial protection and tissue repair in AD.     

Suppression of IL-17A-induced CCL20 production by cytokine inducible SH2-containing protein 1 in epidermal keratinocytes

BackgroundLesions of atopic dermatitis have fewer Th17 cells than those of psoriasis, resulting in frequent skin infections. Expression of CCL20, a chemokine that is important for recruiting Th17 cells, is suppressed in the lesions of atopic dermatitis. We previously reported that IL-4 induces the expression of cytokine-inducible SH2-containing protein 1 (CIS1), a member of the CIS/SOCS family, in epidermal keratinocytes.ObjectiveTo investigate whether CIS1 influences CCL20 production in epidermal keratinocytes.MethodsExpression of CIS1 was examined in atopic dermatitis skin and in cultured keratinocytes. The effects of overexpression of CIS1 on CCL20 production by IL-17A, and on signaling pathways inhibited by CIS1, were assessed in vitro.ResultsExpression of CIS1 was enhanced in the basal layer of the lesional epidermis of skin with atopic dermatitis. When CIS1 was expressed in keratinocytes using adenoviral vectors, IL-17A-induced CCL20 expression, but not HBD2 or S100A7 expression, was significantly suppressed. TNF-α/IL-1-induced CCL20 production was not altered by CIS1. Overexpression of CIS1 attenuated IL-17A-induced ERK phosphorylation. ERK phosphorylation was mediated by the Act1 and Src family kinase pathways. CIS1 overexpression suppressed Src phosphorylation. Among the Src family kinases, the Yes kinase may have an important role because knockdown of Yes in epidermal keratinocytes resulted in suppression of ERK phosphorylation and CCL20 mRNA expression by IL-17A.ConclusionCIS1 induced by Th2 cytokines has the ability to change the response of epidermal keratinocytes to IL-17A by suppression of Src family kinases.     

Osthole attenuates mouse atopic dermatitis by inhibiting thymic stromal lymphopoietin production from keratinocytes

Atopic dermatitis is one of the most common skin diseases. Dysregulation of immune system and chronic inflammation were believed to be associated with atopic dermatitis. Osthole was reported to play important roles in antitumor and anti‐inflammation. However, whether osthole has effects on atopic dermatitis remains unclear. In this present study, we explored the biological role of osthole in atopic dermatitis and the molecular mechanism. Atopic dermatitis was induced by 2,4‐dinitrochlorobenzene. Pathological damage of ear was detected by H&E staining. IgE level in serum or thymic stromal lymphopoietin (TSLP) level in supernatant was detected by ELISA. Interleukin (IL)‐4 expression and IL‐13 expression in CD4⁺ T cells were detected using flow cytometry. The expression levels of mRNA or protein levels were detected by RT‐PCR or Western blot. Osthole attenuated atopic dermatitis development in mouse model. Osthole inhibits Th2 cell response, but have on influence on Th1 or Th17 cell response in the skin. In mouse model, osthole treatment significantly inhibited atopic dermatitis via directly inhibiting TLSP expression levels in keratinocytes. Osthole treatment alleviates atopic dermatitis through directly down‐regulating TSLP production from keratinocytes. Osthole may serve as a potential choice for atopic dermatitis treatment in clinic.