Substance P Antagonist Aprepitant Shows no Additive Effect Compared with Standardized Topical Treatment Alone in Patients with Atopic Dermatitis.

Atopic dermatitis (AD) is a chronic, itchy, inflammatory skin disorder that may worsen due to stress and anxiety. Tachykinins have been suggested to be involved in the inflammation in AD, as well as pruritus. Aprepitant is a NK-1 receptor antagonist. This open randomized trial evaluated the effect of aprepitant added to topical treatment in adult patients with moderate-severe AD. The treatment group (n = 19) received 80 mg/day aprepitant for 7 days as a supplement to standardized topical treatment with a moderately strong steroid and a moisturizer. The control group (n = 20) received topical treatment alone. Patients were monitored for the extent of the disease (using SCORing of Atopic Dermatitis; SCORAD), pruritus, and scratching movements. In both the aprepitant-treated and the control groups there was a decrease in SCORAD, pruritus and scratching movements. However, there was no significant additional improvement in any of these parameters in the aprepitant-treated group compared with the control group.

MicroRNA-125b down-regulates matrix metallopeptidase 13 and inhibits cutaneous squamous cell carcinoma cell proliferation, migration, and invasion.

Cutaneous squamous cell carcinoma (cSCC) is the second most common human cancer. Although dysregulation of microRNAs (miRNAs) is known to be involved in a variety of cancers, the role of miRNAs in cSCC is unclear. In this study, we aimed to identify tumor suppressive and oncogenic miRNAs involved in the pathogenesis of cSCC. MiRNA expression profiles in healthy skins (n = 4) and cSCCs (n = 4) were analyzed using MicroRNA Low Density Array. MiR-125b expression was analyzed by quantitative real-time PCR and in situ hybridization in skin biopsies from 40 healthy donors, 13 actinic keratosis, and 74 cSCC patients. The effect of miR-125b was analyzed in wound closure, colony formation, migration, and invasion assays in two cSCC cell lines, UT-SCC-7 and A431. The genes regulated by miR-125b in cSCC were identified by microarray analysis and its direct target was validated by luciferase reporter assay. Comparing cSCC with healthy skin, we identified four up-regulated miRNAs (miR-31, miR-135b, miR-21, and miR-223) and 54 down-regulated miRNAs, including miR-125b, whose function was further examined. We found that miR-125b suppressed proliferation, colony formation, migratory, and invasive capacity of cSCC cells. Matrix metallopeptidase 13 (MMP13) was identified as a direct target suppressed by miR-125b, and there was an inverse relationship between the expression of miR-125b and MMP13 in cSCC. Knockdown of MMP13 expression phenocopied the effects of miR-125b overexpression. These findings provide a novel molecular mechanism by which MMP13 is up-regulated in cSCCs and indicate that miR-125b plays a tumor suppressive role in cSCC.

Antioxidants protect keratinocytes against M. ulcerans mycolactone cytotoxicity.

BACKGROUND: Mycobacterium ulcerans is the causative agent of necrotizing skin ulcerations in distinctive geographical areas. M. ulcerans produces a macrolide toxin, mycolactone, which has been identified as an important virulence factor in ulcer formation. Mycolactone is cytotoxic to fibroblasts and adipocytes in vitro and has modulating activity on immune cell functions. The effect of mycolactone on keratinocytes has not been reported previously and the mechanism of mycolactone toxicity is presently unknown. Many other macrolide substances have cytotoxic and immunosuppressive activities and mediate some of their effects via production of reactive oxygen species (ROS). We have studied the effect of mycolactone in vitro on human keratinocytes--key cells in wound healing--and tested the hypothesis that the cytotoxic effect of mycolactone is mediated by ROS. METHODOLOGY/PRINCIPAL FINDINGS: The effect of mycolactone on primary skin keratinocyte growth and cell numbers was investigated in serum free growth medium in the presence of different antioxidants. A concentration and time dependent reduction in keratinocyte cell numbers was observed after exposure to mycolactone. Several different antioxidants inhibited this effect partly. The ROS inhibiting substance deferoxamine, which acts via chelation of Fe(2+), completely prevented mycolactone mediated cytotoxicity. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that mycolactone mediated cytotoxicity can be inhibited by deferoxamine, suggesting a role of iron and ROS in mycolactone induced cytotoxicity of keratinocytes. The data provide a basis for the understanding of Buruli ulcer pathology and the development of improved therapies for this disease.

Topical treatment with the vitamin D analogue calcipotriol enhances the upregulation of the antimicrobial protein hCAP18/LL-37 during wounding in human skin in vivo.

Cathelicidin antimicrobial protein, hCAP18, is the sole cathelin protein in human. Its C-terminal peptide, which is released enzymatically from the holoprotein, has broad antimicrobial activity but also has effects on eukaryotic cells. hCAP18 is present in leukocytes and is produced at epithelial interfaces as part of the innate immune system. In normal intact skin, there is low constitutive expression of hCAP18, which is rapidly upregulated upon injury. Accumulating evidence indicates that hCAP18/LL-37 may serve a key role in protecting the integrity of the epithelium and also actively promote re-epithelialization and tissue repair. Molecular mechanisms responsible for controlling hCAP18 gene expression in vivo are only partly understood. Vitamin D(3) and its analogue calcipotriol were recently found to directly induce transcription of the hCAP18 gene via functional vitamin D responsive elements in the hCAP18 gene promoter. Skin is the major source for vitamin D(3) in human, where its production is dependent on ultraviolet B (UVB) radiation. We have shown that exposure to UVB, sufficient to produce vitamin D(3), upregulates hCAP18 in human skin in vivo. In the present study, we demonstrate that the upregulation of hCAP18/LL-37 following acute skin injury is further enhanced, at both hCAP18 mRNA and protein levels, after topical treatment with the vitamin D(3) analogue calcipotriol. In chronic ulcers, calcipotriol treatment upregulated hCAP18 mRNA, whereas no consistent upregulation of hCAP18 protein was detected. Our results further support the role of vitamin D(3) as a key physiologic regulator of hCAP18/LL-37 in human skin.

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

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.

Antimicrobial protein hCAP18/LL-37 is highly expressed in breast cancer and is a putative growth factor for epithelial cells.

Human cathelicidin antimicrobial protein hCAP18/LL-37 is an effector molecule of the nonspecific innate immune system. hCAP18/LL-37 is present in leukocytes and is expressed in skin and other epithelia, where it is upregulated in association with inflammation and injury. In addition, antimicrobial proteins including cathelicidins have been proposed to play a role in the nonspecific defense against tumors. To assess its potential role in tumor host defense, we investigated the expression of hCAP18/LL-37 in a series of breast carcinomas. Unexpectedly, we found that hCAP18/LL-37 was strongly expressed in the tumor cells and not in the adjacent stroma. To test the hypothesis that hCAP18/LL-37 may provide a growth advantage for the tumor cells, we treated human epithelial cell lines with synthetic biologically active LL-37 peptide and found a significant increase in cell proliferation. In addition, transgenic expression of hCAP18 in 2 different human epithelial cell lines resulted in increased proliferation of both cell types. These findings do not support the hypothesis that LL-37 has an antitumor effect, but rather suggest that hCAP18/LL-37 may promote tumor cell growth in breast cancer.

The cathelicidin anti-microbial peptide LL-37 is involved in re-epithelialization of human skin wounds and is lacking in chronic ulcer epithelium.

The human cathelicidin anti-microbial protein, hCAP18 is a component of the innate immune system and has broad anti-microbial activity conferred by its C-terminal fragment LL-37. hCAP18 is constitutively produced in leukocytes and is induced in barrier organs upon inflammation and infection. We demonstrate here a novel role for this peptide in re-epithelialization of skin wounds. We show that high levels of hCAP18 are produced in skin in vivo upon wounding. The highest hCAP18 levels are attained at 48 h post-injury, declining to pre-injury levels upon wound closure. hCAP18 is detected in the inflammatory infiltrate and in the epithelium migrating over the wound bed. In chronic ulcers, however, hCAP18 levels are low and immunoreactivity for hCAP18/LL-37 is absent in ulcer edge epithelium. Using a noninflammatory ex vivo wound healing model, composed of organ-cultured human skin, we show that hCAP18 is strongly expressed in healing skin epithelium, and that treatment with antibodies raised and affinity purified against LL-37, inhibits re-epithelialization in a concentration-dependent manner. Immunoreactivity for the proliferation marker Ki67 is absent in the epithelium of such inhibited wounds, suggesting that LL-37 may play a part in epithelial cell proliferation. Thus, we suggest that, in addition to being an anti-microbial peptide, LL-37 also plays a part in wound closure and that its reduction in chronic wounds impairs re-epithelialization and may contribute to their failure to heal.