Murine Keratinocytes Research Articles

Keratins Regulate the Adhesive Properties of Desmosomal Cadherins through Signaling

Tightly controlled intercellular adhesion is crucial for the integrity and function of the epidermis. The keratin filament cytoskeleton anchors desmosomes, supramolecular complexes required for strong intercellular adhesion. We tested whether keratin filaments control cell adhesion by regulating the adhesive properties of desmosomal cadherins such as desmoglein (Dsg) 3. Atomic force microscopy and fluorescence recovery after photobleaching experiments showed reduced Dsg3 adhesive forces and membrane stability in murine keratinocytes lacking all keratin filaments. Impairment of the actin cytoskeleton also resulted in decreased Dsg3 immobilization but did not affect Dsg3 binding properties, indicating that the latter are exclusively controlled by keratins. Reduced binding forces were dependent on p38 mitogen-activated protein kinase activity, which was deregulated in keratin-deficient cells. In contrast, inhibition of protein kinase C signaling, which is known to be controlled by keratins, promoted and spatially stabilized Dsg3-mediated interactions in the membrane. These results show a previously unreported mechanism for how keratins stabilize intercellular adhesion on the level of single desmosomal adhesion molecules.

453 The role of purinergic signaling in development of irritant dermatitis of acrodermatitis enteropathica

Purinergic signaling is crucial to maintain homeostasis of inflammation. We previously elucidated that disruption of the homeostasis of skin inflammation by Zn deficiency-mediated ablation of Langerhans cells (LCs) that expressed CD39 (E-NTPDase1) was causative for development of dermatitis in acrodermatitis enteropathica. ATP was hydrolyzed into AMP by E-NTPDases (Entpd), E-NPPs (Enpp), and tissue non-specific alkaline phosphatases (TNAP). It has been well known that LCs express Entpd1 (CD39) and keratinocytes (KCs) do not express it in both mice and humans. However, the expression of other ATP-hydrolyzing molecules such as Entpd 2-3, Enpp 1-3, and TNAP in LCs and KCs is not addressed so far. The purpose of this study is 1. to determine the expression of these ATP-hydrolyzing molecules in LCs and KCs of both mice and humans by qPCR, and 2. to examine the alteration of expression of these ATP-hydrolyzing molecules under Zn deficient condition by qPCR. Normal murine KCs expressed Entpd2, Enpp1, and low levels of Enpp2 and TNAP, whereas normal human epidermal KCs (NHEKs) expressed Entpd2, Entpd3, and Enpp1. Normal murine LCs expressed Entpd1 (CD39), Entpd2, and low level of Enpp1, whereas normal human LCs expressed Entpd1 (CD39), and low levels of Enpp2 and Enpp3. KCs from Zn-deficient diet mice showed increased expression of Entpd2 and Enpp1, and loss of expression of Enpp2 and TNAP. Finally, we examined the impact of LCs in ATP hydrolysis. ATP hydrolysis activity was determined by measuring released phosphate. ATP hydrolysis activity was impaired up to 82% in LC-depleted murine epidermis compared with LC-existing murine epidermis. These data suggested that the expression of ATP-hydrolyzing molecules in LCs and KCs were different between mice and humans. Additionally, Zn deficiency altered the expression of ATP-hydrolyzing molecules in KCs. Lastly, Entpd1 (CD39)- and Entpd2-expressing LCs assumed about 80% of ATP hydrolysis, whereas Entpd2- and Enpp1-expressing KCs assumed the remaining 20% ATP hydrolysis in murine epidermis.

Adenovirus vector expressing keratinocyte growth factor using CAG promoter impairs pulmonary function of mice with elastase-induced emphysema.

Pulmonary emphysema impairs quality of life and increases mortality. It has previously been shown that administration of adenovirus vector expressing murine keratinocyte growth factor (KGF) before elastase instillation prevents pulmonary emphysema in mice. We therefore hypothesized that therapeutic administration of KGF would restore damage to lungs caused by elastase instillation and thus improve pulmonary function in an animal model. KGF expressing adenovirus vector, which prevented bleomycin-induced pulmonary fibrosis in a previous study, was constructed. Adenovirus vector (1.0 × 109 plaque-forming units) was administered intratracheally one week after administration of elastase into mouse lungs. One week after administration of KGF-vector, exercise tolerance testing and blood gas analysis were performed, after which the lungs were removed under deep anesthesia. KGF-positive pneumocytes were more numerous, surfactant protein secretion in the airspace greater and mean linear intercept of lungs shorter in animals that had received KGF than in control animals. Unexpectedly, however, arterial blood oxygenation was worse in the KGF group and maximum running speed, an indicator of exercise capacity, had not improved after KGF in mice with elastase-induced emphysema, indicating that KGF-expressing adenovirus vector impaired pulmonary function in these mice. Notably, vector lacking KGF-expression unit did not induce such impairment, implying that the KGF expression unit itself may cause the damage to alveolar cells. Possible involvement of the CAG promoter used for KGF expression in impairing pulmonary function is discussed.

Full Length Interleukin 33 Aggravates Radiation-Induced Skin Reaction.

The interleukin (IL)-1 family member IL-33 has been described as intracellular alarmin with broad roles in wound healing, skin inflammation but also autoimmunity. Its dichotomy between full length (fl) IL-33 and the mature (m) form of IL-33 and its release by necrosis is still not fully understood. Here, we compare functional consequences of both forms in the skin in vivo, and therefore generated two lines of transgenic mice which selectively overexpress mmIL-33 and flmIL-33 in basal keratinocytes. Transgene mRNA was expressed at high level in skin of both lines but not in organs due to the specific K14 promoter. We could demonstrate that transgenic overexpression of mmIL-33 in murine keratinocytes leads to a spontaneous skin inflammation as opposed to flmIL-33. K14-mmIL-33 mice synthesize and secrete high amounts of mmIL-33 along with massive cutaneous manifestations, like increased epidermis and dermis thickness, infiltration of mast cells in the epidermis and dermis layers and marked hyperkeratosis. Using skin inflammation models such as IL-23 administration, imiquimod treatment, or mechanical irritation did not lead to exacerbated inflammation in the K14-flmIL-33 strain. As radiation induces a strong dermatitis due to apoptosis and necrosis, we determined the effect of fractionated radiation (12 Gy, 4 times). In comparison to wild-type mice, an increase in ear thickness in flmIL-33 transgenic mice was observed 25 days after irradiation. Macroscopic examination showed more severe skin symptoms in irradiated ears compared to controls. In summary, secreted mmIL-33 itself has a potent capacity in skin inflammation whereas fl IL-33 is limited due to its intracellular retention. During tissue damage, fl IL-33 exacerbated radiation-induced skin reaction.

Development of a new model of reconstituted mouse epidermis and characterization of its response to proinflammatory cytokines.

The development of three-dimensional models of reconstituted mouse epidermis (RME) has been hampered by the difficulty to maintain murine primary keratinocyte cultures and to achieve a complete epidermal stratification. In this study, a new protocol is proposed for the rapid and convenient generation of RME, which reproduces accurately the architecture of a normal mouse epidermis. During RME morphogenesis, the expression of differentiation markers such as keratins, loricrin, filaggrin, E-cadherin and connexins was followed, showing that RME structure at day 5 was similar to those of a normal mouse epidermis, with the acquisition of the natural barrier function. It was also demonstrated that RME responded to skin-relevant proinflammatory cytokines by increasing the expression of antimicrobial peptides and chemokines, and inhibiting epidermal differentiation markers, as in the human system. This new model of RME is therefore suitable to investigate mouse epidermis physiology further and opens new perspectives to generate reconstituted epidermis from transgenic mice.

TWEAK/Fn14 Activation Participates in Ro52-Mediated Photosensitization in Cutaneous Lupus Erythematosus.

Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) binds to its sole receptor fibroblast growth factor-inducible 14 (Fn14), participating in various inflammatory responses. Recently, TWEAK/Fn14 activation was found prominent in the lesions of cutaneous lupus erythematosus (CLE). This study was designed to further reveal the potential role of this pathway in Ro52-mediated photosensitization. TWEAK, Fn14, and Ro52 were determined in the skin lesions of patients with CLE. Murine keratinocytes received ultraviolet B (UVB) irradiation or plus TWEAK stimulation and underwent detection for Ro52 and proinflammatory cytokines. The chemotaxis of J774.2 macrophages was evaluated on TWEAK stimulation of cocultured keratinocytes. We found that TWEAK, Fn14, and downstream cytokines were highly expressed in CLE lesions that overexpressed Ro52. Moreover, TWEAK enhanced the UVB-induced Ro52 upregulation in murine keratinocytes. Meanwhile, TWEAK stimulation of keratinocytes favored the migration of macrophages through promoting the production of chemokine C–C motif ligands 17 and 22. Furthermore, Fn14 siRNA transfection or nuclear factor-kappa B (NF-κB) inhibitor abrogated the TWEAK enhancement of Ro52 expression in keratinocytes. Similarly, TNF receptor associated factor 2 (TRAF2) siRNA reduced the protein level of Ro52 in these cells upon TWEAK stimulation. Interestingly, UVB irradiation increased the expression of TNF receptor type 1 (TNFR1) but not affecting TNFR2 expression in keratinocytes. In conclusion, the TWEAK/Fn14 signaling participates in Ro52-mediated photosensitization and involves the activation of NF-κB pathway as well as the function of the TRAF2/TNFR partners.

Retinoic acid receptor-related orphan receptor RORα regulates differentiation and survival of keratinocytes during hypoxia.

Low O2 pressures present in the microenvironment of epidermis control keratinocyte differentiation and epidermal barrier function through hypoxia inducible factors (HIFs) dependent gene expression. This study focuses on investigating relations of the retinoic acid receptor-related orphan receptor alpha (RORα) to HIF-1α in keratinocytes under hypoxic conditions. The expression level of RORα is significantly elevated under hypoxia in both human and murine keratinocytes. Gene silencing of RORA attenuates hypoxia-stimulated expression of genes related to late differentiation and epidermal barrier function, and leads to an enhanced apoptotic response. While the hypoxic induction of RORα is dependent on HIF-1α, RORα is in turn critical for nuclear accumulation of HIF-1α and activation of HIF transcriptional activity. These results collectively suggest that RORα functions as an important mediator of HIF-1α activities in regulating keratinocyte differentiation/survival and epidermal barrier function during the oxygen sensing stage.

TWEAK/Fn14 activation is instrumental in Ro52-mediated photosensitization in cutaneous lupus erythematosus

Abstract Background TWEAK, a member of the TNF superfamily, binds to the Fn14 receptor, participating in many pathological alterations. Ro52 autoantigen mediates the photosensitization of lupus erythematosus. Recently, TWEAK/Fn14 activation was found in the lesion of cutaneous lupus erythematosus (CLE). Objectives To further show the potential role of TWEAK/Fn14 pathway in Ro52-mediated photosensitization. Methods The expression of TWEAK and Fn14 was detected in skin tissues from patients with LE and healthy donors. The expression of Ro52 was determined in murine keratinocytes that were treated with TWEAK or plus UVB irradiation. Some cells were pretreated with siRNA transfection or specific inhibitors of signaling pathways. The chemotaxis of J774.2 macrophages was evaluated on TWEAK stimulation of cocultured keratinocytes. The expression of TNF receptor associated factor 2 (TRAF2) and TNF receptors (TNFR) was determined in keratinocytes upon UVB or plus TWEAK treatment. Results TWEAK, Fn14, and downstream cytokines were highly expressed in CLE lesions that overexpressed Ro52. Moreover, TWEAK promoted the enhancement effect of UVB on Ro52 expression in keratinocytes. Meanwhile, TWEAK stimulation of keratinocytes favored the migration of macrophages. Furthermore, nuclear factor-kappa B inhibitor or Fn14 siRNA transfection abrogated the TWEAK effect on Ro52 regulation. Similarly, TRAF2 siRNA attenuated the TWEAK effect on Ro52 expression. Interestingly, UVB irradiation increased the expression of TNFR1 but decreased TNFR2 expression in keratinocytes. Conclusion TWEAK/Fn14 activation is instrumental in Ro52-mediated photosensitization and involves the function of the Fn14-TRAF2-TNFR axis.

The cytosolic DNA- and RNA-sensing pathways play important and non-redundant roles in host defense against vaccinia infection

Abstract Vaccinia virus is a prototypic poxvirus, and during the life cycle of the virus, viral DNA and RNA can be detected by the nucleic acid-sensing pathways to induce the expression of type I IFN and IFN-stimulating genes, which leads to the establishment of antiviral state. Poxviruses have evolved multiple strategies to evade host immunity. Vaccinia E3, which consists of two distinct Z-DNA-binding and dsRNA-binding domains, is a critical virulence factor. Virus lacks E3L gene (ΔE3L) is non-pathogenic in wild-type mice in an intranasal infection model. We have previously reported that ΔE3L infection of murine primary keratinocytes (KCs) induces Ifnb, Il6, Ccl5 and Ccl4 gene expression and protein secretion via a MAVS/IRF3-dependent mechanism. Here we show that MDA5, a cytosolic dsRNA sensor, is essential for the induction of innate immunity by ΔE3L in KCs, whereas PKR, another cytosolic dsRNA sensor, is not. ΔE3L gains virulence in MDA5, MAVS, or IRF3-deficient mice, but not in STING-or MyD88-deficient mice, in an intranasal infection model. The MDA5-, MAVS-, or IRF3-deficient mice lost 20% of weight but all recovered in response to ΔE3L infection. By contrast, both the MDA5 and STING-mediated sensing pathways contribute to host defense against WT vaccinia virus infection. Lastly, whereas ΔE3L virus fails to replicate in wild-type murine primary fibroblasts, it gains replication capacity in cGAS or STING-deficient murine primary fibroblasts. Taken together, these results indicate that vaccinia viral nucleic acids are detected via the cytosolic DNA- and/or RNA-sensing pathways in a cell-type dependent manner, and both pathways play important and non-redundant roles in host defense against vaccinia infection.

Autophagy deficient keratinocytes display increased DNA damage, senescence and aberrant lipid composition after oxidative stress in vitro and in vivo

Autophagy allows cells fundamental adaptations to metabolic needs and to stress. Using autophagic bulk degradation cells can clear crosslinked macromolecules and damaged organelles that arise under redox stress. Accumulation of such debris results in cellular dysfunction and is observed in aged tissue and senescent cells. Conversely, promising anti-aging strategies aim at inhibiting the mTOR pathway and thereby activating autophagy, to counteract aging associated damage. We have inactivated autophagy related 7 (Atg7), an essential autophagy gene, in murine keratinocytes (KC) and have found in an earlier study that this resulted in increased baseline oxidative stress and reduced capacity to degrade crosslinked proteins after oxidative ultraviolet stress. To investigate whether autophagy deficiency would promote cellular aging, we studied how Atg7 deficient (KO) and Atg7 bearing cells (WT) would respond to stress induced by paraquat (PQ), an oxidant drug commonly used to induce cellular senescence.Atg7 deficient KC displayed increased prostanoid signaling and a pro- mitotic gene expression signature as compared to the WT. After exposure to PQ, both WT and KO cells showed an inflammatory and stress-related transcriptomic response. However, the Atg7 deficient cells additionally showed drastic DNA damage- and cell cycle arrest signaling. Indeed, DNA fragmentation and –oxidation were strongly increased in the stressed Atg7 deficient cells upon PQ stress but also after oxidizing ultraviolet A irradiation. Damage associated phosphorylated histone H2AX (γH2AX) foci were increased in the nuclei, whereas expression of the nuclear lamina protein lamin B1 was strongly decreased. Similarly, in both, PQ treated mouse tail skin explants and in UVA irradiated mouse tail skin, we found a strong increase in γH2AX positive nuclei within the basal layer of Atg7 deficient epidermis.Atg7 deficiency significantly affected expression of lipid metabolic genes. Therefore we performed lipid profiling of keratinocytes which demonstrated a major dysregulation of cellular lipid metabolism. We found accumulation of autophagy agonisitic free fatty acids, whereas triglyceride levels were strongly decreased. Together, our data show that in absence of Atg7/autophagy the resistance of keratinocytes to intrinsic and environmental oxidative stress was severely impaired and resulted in DNA damage, cell cycle arrest and a disturbed lipid phenotype, all typical for premature cell aging.

IL-1 Coordinates the Neutrophil Response to C. albicans in the Oral Mucosa.

Mucosal infections with Candida albicans belong to the most frequent forms of fungal diseases. Host protection is conferred by cellular immunity; however, the induction of antifungal immunity is not well understood. Using a mouse model of oropharyngeal candidiasis (OPC) we show that interleukin-1 receptor (IL-1R) signaling is critical for fungal control at the onset of infection through its impact on neutrophils at two levels. We demonstrate that both the recruitment of circulating neutrophils to the site of infection and the mobilization of newly generated neutrophils from the bone marrow depended on IL-1R. Consistently, IL-1R-deficient mice displayed impaired chemokine production at the site of infection and defective secretion of granulocyte colony-stimulating factor (G-CSF) in the circulation in response to C. albicans. Strikingly, endothelial cells were identified as the primary cellular source of G-CSF during OPC, which responded to IL-1α that was released from keratinocytes in the infected tissue. The IL-1-dependent crosstalk between two different cellular subsets of the nonhematopoietic compartment was confirmed in vitro using a novel murine tongue-derived keratinocyte cell line and an established endothelial cell line. These data establish a new link between IL-1 and granulopoiesis in the context of fungal infection. Together, we identified two complementary mechanisms coordinating the neutrophil response in the oral mucosa, which is critical for preventing fungal growth and dissemination, and thus protects the host from disease.

Stimulation of the histamine 4 receptor upregulates thymic stromal lymphopoietin (TSLP) in human and murine keratinocytes

The cytokine thymic stromal lymphopoietin (TSLP) is involved in the development and the progression of allergic diseases. It is mainly released by epithelial cells at barriers such as skin and gut in response to danger signals. Overexpression of TSLP in keratinocytes (KC) can provoke the development of a type 2 inflammatory response. Additionally, TSLP directly acts on sensory neurons and thereby triggers itch. Since histamine is also increased in lesions of inflammatory skin diseases, the aim of this study was to investigate possible effects of histamine as well as different histamine receptor subtype agonists and antagonists on TSLP production in KC. We therefore stimulated human KC with histamine in the presence or absence of the known TSLP-inductor poly I:C and measured TSLP production at protein as well as mRNA level. Histamine alone did not induce TSLP production in human KC, but pre-incubation with histamine prior to challenge with poly I:C resulted in a significant increase of TSLP production compared to stimulation with poly I:C alone. Experiments with different histamine receptor agonists (H1R: 2-pyridylethylamine; H2R: amthamine; H2R/H4R: 4-methylhistamine (4MH)) revealed a dominant role for the H4R receptor, as 4-MH in combination with poly I:C displayed a significant increase of TSLP secretion, while the other agonists did not show any effect. The increase in TSLP production by 4MH was blocked with the H4R antagonist JNJ7777120. This effect was reproducible also in the murine KC cell line MSC.Taken together, our study indicates a new role for the H4 receptor in the regulation of TSLP in keratinocytes. Therefore, blocking of the H4R receptor in allergic diseases might be promising to alleviate inflammation and pruritus via TSLP.

Nanofibrous polycaprolactone scaffolds with adhered platelets stimulate proliferation of skin cells.

Faulty wound healing is a global healthcare problem. Chronic wounds are generally characterized by a reduction in availability of growth factors. New strategies are being developed to deliver growth factors more effectively. In this study, we introduced electrospun scaffolds composed of polycaprolactone (PCL) nanofibers functionalized with adhered platelets, as a source of numerous growth factors. Three concentrations of platelets were immobilized to nanofibrous scaffolds by simple adhesion, and their influence on adhesion, proliferation and metabolic activity of seeded cells (murine fibroblasts, keratinocytes and melanocytes) was investigated. The data obtained indicated that presence of platelets significantly promoted cell spreading, proliferation and metabolic activity in all the skin-associated cell types. There were no significant differences among tested concentrations of platelets, thus even the lowest concentration sufficiently promoted proliferation of the seeded cells. Such complex stimulation is needed for improved healing of chronic wounds. However, the nanofibrous system can be used not only as a skin cover, but also in broader applications in regenerative medicine.

Oncostatin M overexpression induces skin inflammation but is not required in the mouse model of imiquimod-induced psoriasis-like inflammation.

Oncostatin M (OSM) has been reported to be overexpressed in psoriasis skin lesions and to exert proinflammatory effects in vitro on human keratinocytes. Here, we report the proinflammatory role of OSM in vivo in a mouse model of skin inflammation induced by intradermal injection of murine OSM-encoding adenovirus (AdOSM) and compare with that induced by IL-6 injection. Here, we show that OSM potently regulates the expression of genes involved in skin inflammation and epidermal differentiation in murine primary keratinocytes. In vivo, intradermal injection of AdOSM in mouse ears provoked robust skin inflammation with epidermal thickening and keratinocyte proliferation, while minimal effect was observed after AdIL-6 injection. OSM overexpression in the skin increased the expression of the S100A8/9 antimicrobial peptides, CXCL3, CCL2, CCL5, CCL20, and Th1/Th2 cytokines, in correlation with neutrophil and macrophage infiltration. In contrast, OSM downregulated the expression of epidermal differentiation genes, such as cytokeratin-10 or filaggrin. Collectively, these results support the proinflammatory role of OSM when it is overexpressed in the skin. However, OSM expression was not required in the murine model of psoriasis induced by topical application of imiquimod, as demonstrated by the inflammatory phenotype of OSM-deficient mice or wild-type mice treated with anti-OSM antibodies.

477 Ablation of DLX3 in adult murine keratinocytes lead to deregulation of cell cycle and infiltration of IL-17 producing leukocytes

DLX3, a homeobox transcription factor, is highly expressed in the epithelial compartment of skin and teeth. We previously reported that mice lacking DLX3 in epidermis had alopecia, skin barrier defects and enhanced IL-17-associated skin inflammation. Based on these observations, we hypothesized that the initial signals such as inflammatory cytokines that are produced by Dlx3-null keratinocytes result in the infiltration of antigen-presenting cells and T cells into the dermis with subsequent IL-17A production. To identify the triggering signals from Dlx3-null keratinocytes and the reciprocal signaling crosstalk between epidermis and dermis that stimulate inflammation, we performed acute deletion of Dlx3 in adult epidermal keratinocytes using a tamoxifen-inducible K14cre-ERT system (K14creERT; Dlx3f/f). Using flow cytometry analysis, we characterized the inflammatory cells that infiltrate the skin from immediate to late stages after deletion of Dlx3. We also analyzed the signaling molecules or inflammatory cytokines that are differentially regulated in epidermis and dermis of K14creERT; Dlx3f/f and corresponding control littermates using RNA-seq profiling. We observed dermal accumulations of macrophages and neutrophils within 3 days of tamoxifen-induced Dlx3 ablation, with enhanced infiltration after one week and two weeks after deletion. We also identified increased numbers of IL-17 secreting Vg4+gdT-cells in the dermis one week and two weeks after Dlx3 deletion. We detected changes in cell-cycle machinery and subsequent production of IL-1 and IL-17 cytokines through RNA-seq analysis of Dlx3-ablated epidermis at several time points after tamoxifen treatment (3day, 1 and 2 weeks).Our preliminary results suggest a critical function of DLX3 in regulating mechanisms that are required for the maintenance of normal epidermal homeostasis.

410 The application of ATAC-seq to murine keratinocytes in the elucidation of the role of DLX3 in epidermal differentiation

410 The application of ATAC-seq to murine keratinocytes in the elucidation of the role of DLX3 in epidermal differentiation

Detection of Murine TRPA1 Transcripts in Keratinocytes

Background: Transient receptor potential ankyrin 1 (TRPA1) is expressed by nociceptive neurons of the dorsal root ganglia (DRGs) and trigeminal ganglia, but its expression in other cell types is largely unexplored. TRPA1 contributes to chemical, mechanical and cold nociception and expression of TRPA1 in keratinocytes may extend the detection of chemical and physical stimuli from the nerve endings to the surface of the skin. Results: Comparison of TRPA1 genes from multiple inbred mouse lines revealed a large number of genetic variations in the TRPA1 locus. These genetic variations may affect annealing of primers to detect TRPA1 transcript when using nucleic acid-based methods. To consistently detect TRPA1 in genetically diverse mouse strains and in different tissue types, an optimized qPCR protocol for TRPA1 detection was created. Conclusions: TRPA1 transcripts are consistently detected in murine keratinocytes.

Mechanosensory and ATP Release Deficits following Keratin14-Cre-Mediated TRPA1 Deletion Despite Absence of TRPA1 in Murine Keratinocytes.

Keratinocytes are the first cells that come into direct contact with external tactile stimuli; however, their role in touch transduction in vivo is not clear. The ion channel Transient Receptor Potential Ankyrin 1 (TRPA1) is essential for some mechanically-gated currents in sensory neurons, amplifies mechanical responses after inflammation, and has been reported to be expressed in human and mouse skin. Other reports have not detected Trpa1 mRNA transcripts in human or mouse epidermis. Therefore, we set out to determine whether selective deletion of Trpa1 from keratinocytes would impact mechanosensation. We generated K14Cre-Trpa1fl/fl mice lacking TRPA1 in K14-expressing cells, including keratinocytes. Surprisingly, Trpa1 transcripts were very poorly detected in epidermis of these mice or in controls, and detection was minimal enough to preclude observation of Trpa1 mRNA knockdown in the K14Cre-Trpa1fl/fl mice. Unexpectedly, these K14Cre-Trpa1fl/fl mice nonetheless exhibited a pronounced deficit in mechanosensitivity at the behavioral and primary afferent levels, and decreased mechanically-evoked ATP release from skin. Overall, while these data suggest that the intended targeted deletion of Trpa1 from keratin 14-expressing cells of the epidermis induces functional deficits in mechanotransduction and ATP release, these deficits are in fact likely due to factors other than reduction of Trpa1 expression in adult mouse keratinocytes because they express very little, if any, Trpa1.

A Gene Gun-mediated Nonviral RNA trans-splicing Strategy for Col7a1 Repair.

RNA trans-splicing represents an auspicious option for the correction of genetic mutations at RNA level. Mutations within COL7A1 causing strong reduction or absence of type VII collagen are associated with the severe skin blistering disease dystrophic epidermolysis bullosa. The human COL7A1 mRNA constitutes a suitable target for this RNA therapy approach, as only a portion of the almost 9 kb transcript has to be delivered into the target cells. Here, we have proven the feasibility of 5' trans-splicing into the Col7a1 mRNA in vitro and in vivo. We designed a 5' RNA trans-splicing molecule, capable of replacing Col7a1 exons 1-15 and verified it in a fluorescence-based trans-splicing model system. Specific and efficient Col7a1 trans-splicing was confirmed in murine keratinocytes. To analyze trans-splicing in vivo, we used gene gun delivery of a minicircle expressing a FLAG-tagged 5' RNA trans-splicing molecule into the skin of wild-type mice. Histological and immunofluorescence analysis of bombarded skin sections revealed vector delivery and expression within dermis and epidermis. Furthermore, we have detected trans-spliced type VII collagen protein using FLAG-tag antibodies. In conclusion, we describe a novel in vivo nonviral RNA therapy approach to restore type VII collagen expression for causative treatment of dystrophic epidermolysis bullosa.

Putative Roles of SOCS1: SOCS 3 Ratios in Development and Resolution of a Herpesvirus Lesion

This article is the author’s opinion of the effects of the cytokines produced as a result of epithelial cell macrophage interactions during herpes simplex virus type 1(HSV-1) infection. Cell cultures of murine keratinocytes were examined for SOCS1 production following HSV-1 infection and macrophage cell lines were examined for cytokine production following polarization and modification of cytokine production by peptide mimetics of suppressors of the cytokine signaling (SOCS) molecules SOCS1 and SOCS3. It is speculated that the pro inflammatory cytokines produced by M1 polarized cells enhance the inflammatory nature of the lesion produced by HSV-1 and the anti-inflammatory cytokines of the M2 polarized cells promote resolution of the lesion.