Inflammatory Mediator TAK1 Regulates Hair Follicle Morphogenesis and Anagen Induction Shown by Using Keratinocyte-Specific TAK1-Deficient Mice

Transforming growth factor-β-activated kinase 1 (TAK1) is a member of the NF-κB pathway and regulates inflammatory responses. We previously showed that TAK1 also regulates keratinocyte growth, differentiation, and apoptosis. However, it is unknown whether TAK1 has any role in epithelial–mesenchymal interactions. To examine this possibility, we studied the role of TAK1 in mouse hair follicle development and cycling as an instructive model system. By comparing keratinocyte-specific TAK1-deficient mice (Map3k7fl/flK5-Cre) with control mice, we found that the number of hair germs (hair follicles precursors) in Map3k7fl/flK5-Cre mice was significantly reduced at E15.5, and that subsequent hair follicle morphogenesis was retarded. Next, we analyzed the role of TAK1 in the cyclic remodeling in follicles by analyzing hair cycle progression in mice with a tamoxifen-inducible keratinocyte-specific TAK1 deficiency (Map3k7fl/flK14-Cre-ERT2). After active hair growth (anagen) was induced by depilation, TAK1 was deleted by topical tamoxifen application. This resulted in significantly retarded anagen development in TAK1-deficient mice. Deletion of TAK1 in hair follicles that were already in anagen induced premature, apoptosis-driven hair follicle regression, along with hair follicle damage. These studies provide the first evidence that the inflammatory mediator TAK1 regulates hair follicle induction and morphogenesis, and is required for anagen induction and anagen maintenance

Effects of Chemical Short-Range Order and Lattice Distortion on Crack-Tip Behavior of Medium-Entropy Alloy by Atomistic Simulations

It is well demonstrated that the complex chemical fluctuations on high/medium-entropy alloys (H/MEAs) play critical roles in their deformation process, but there are few reports related to the effect of such complex chemical fluctuations on the crack behavior. In this paper, the effects of chemical short-range order (CSRO) and lattice distortion (LD) on the crack-tip behavior of CrCoNi MEAs under mode I loading at room temperature are investigated by carrying out molecular dynamics (MD) simulation, hybrid MD/Monte-Carlo (MC) simulation and the J-integral method. The results reveal that CSRO can improve the J-integral value without significant changes in the localized deformation zone size. On the contrary, LD can lower the J-integral value with an increase in the localized deformation zone size. The energetic analysis shows that CSRO improves the activation energy barrier of Shockley partial dislocation from the crack-tip while LD reduces the activation energy barrier. Our work is a step forward in understanding the effects of CSRO and LD on the crack-tip behavior and deformation mechanisms of CrCoNi MEAs

Nuclear IL-33 Plays an Important Role in EGFR-Mediated Keratinocyte Migration by Regulating the Activation of Signal Transducer and Activator of Transcription 3 and NF-κB

Nuclear IL-33 levels are high at the epidermal edges of skin wounds and facilitate wound healing. However, IL-33−mediated regulation of keratinocyte (KC) biology during wound healing remains poorly understood. During skin-wound healing, KC migration and re-epithelialization are mediated predominantly by EGFR signaling activation and depend on the function of signal transducer and activator of transcription 3 (STAT3). We found that migrating KCs at the leading edges of mouse skin wounds exhibited concomitant induction and nuclear colocalization of IL-33 and phosphorylated STAT3. In cultured human KCs, activation of EGFR signaling caused rapid elevation of nuclear IL-33, which directly interacts with phosphorylated STAT3, promoting STAT3 activation. In vitro KC migration and wound-healing assays revealed that high nuclear IL-33 levels were required for KC migration and wound closure. KC mobility associated with a lack of suprabasal epidermal keratins and extracellular matrix degradation mediated by matrix metalloproteinases (MMPs) control cell migration at the intracellular and extracellular levels, respectively. In EGFR-activated KCs, nuclear IL-33 mediated keratin 1 and 10 downregulation and MMP9 upregulation by promoting STAT3 activation and limited MMP1, MMP3, and MMP10 induction by suppressing NF-κB transactivation. Thus, epidermal nuclear IL-33 is involved in KC migration and wound closure by regulating the STAT3 and NF-κB pathways

Vesicular LL-37 contributes to inflammation of the lesional skin of palmoplantar pustulosis.

"Pustulosis palmaris et plantaris", or palmoplantar pustulosis (PPP), is a chronic pustular dermatitis characterized by intraepidermal palmoplantar pustules. Although early stage vesicles (preceding the pustular phase) formed in the acrosyringium contain the antimicrobial peptides cathelicidin (hCAP-18/LL-37) and dermcidin, the details of hCAP-18/LL-37 expression in such vesicles remain unclear. The principal aim of the present study was to clarify the manner of hCAP-18/LL-37 expression in PPP vesicles and to determine whether this material contributed to subsequent inflammation of lesional skin. PPP vesicle fluid (PPP-VF) induced the expression of mRNAs encoding IL-17C, IL-8, IL-1α, and IL-1β in living skin equivalents, but the level of only IL-8 mRNA decreased significantly upon stimulation of PPP vesicle with depletion of endogenous hCAP-18/LL-37 by affinity chromatography (dep-PPP-VF). Semi-quantitative dot-blot analysis revealed higher concentrations of hCAP-18/LL-37 in PPP-VF compared to healthy sweat (2.87±0.93 µM vs. 0.09±0.09 µM). This concentration of hCAP-18/LL-37 in PPP-VF could upregulate expression of IL-17C, IL-8, IL-1α, and IL-1β at both the mRNA and protein levels. Recombinant hCAP-18 was incubated with dep-PPP-VF. Proteinase 3, which converts hCAP-18 to the active form (LL-37), was present in PPP-VF. Histopathological and immunohistochemical examination revealed that early stage vesicles contained many mononuclear cells but no polymorphonuclear cells, and the mononuclear cells were CD68-positive. The epidermis surrounding the vesicle expresses monocyte chemotactic chemokine, CCL2. In conclusion, PPP-VF contains the proteinase required for LL-37 processing and also may directly upregulate IL-8 in lesional keratinocytes, in turn contributing to the subsequent inflammation of PPP lesional skin

The activation of IL-31 signal in keratinocytes.

<p>(A) Keratinocytes were treated with IL-31 (0∼10 ng/ml) for 8 h, the mRNA expression of CCL2, IL-8 and IL-1β were examined by real time PCR. Relative mRNA levels are expressed as means±SD (<i>n</i> = 3). *<i>p</i><0.05: compared to that of control. (B) Keratinocytes were treated with IL-31 (10 ng/ml) for the indicated times, the levels of phospho-ERK, ERK, phospho-STAT3 and STAT3 were decided by western blotting. (The bands for phospho-STAT1 and phospho-AKT were not detected) (C) Keratinocytes were primed with IL-1Ra for 1h before stimulated with IL-31 (10 ng/ml) or IL-1α (10 ng/ml) for 8 h, the mRNA expression of CCL2, IL-1β and IL-8 was detected by real time PCR of total RNA and their relative mRNA levels were expressed as means±SD (<i>n</i> = 3). *<i>p</i><0.05: compared to that without IL-1Ra (D) Keratinocytes were treated with IFN-γ (100 mg/ml), IL-4 (10 ng/ml), or IL-13 (50 ng/ml) for 6 h, the mRNA expression of IL-31RA and OSMR was examined by RT-PCR. (E) Keratinocytes were pretreated with IFN-γ for 24 h, then stimulated with or without IL-31 for 8 h, the mRNA expression of CCL2 were examined by real time PCR. Relative mRNA levels are expressed as means SD (<i>n</i> = 3). *<i>p</i><0.05: compared to that of IFN-γ stimulation only.</p

The bioactivity of sweat IL-1 is required for sweat-mediated keratinocyte activation.

<p>(A) To block the activation of IL-1 signaling, different concentration of IL-1Ra was applied into cultures for 1 h before stimulation with IL-1β for 24 h, the secretion of IL-8 was detected by ELISA of supernatants. Concentrations represent means±SD (<i>n</i> = 3). *<i>p</i><0.05: compared to that of IL-1β stimulation only. (B) 100 ng/ml IL-1Ra was applied into cultures for 1 h before the addition of concentrated sweat obtained from volunteer 3, keratinocytes were collected after 10 min of stimulation and the phosphorylation of IκBα, ERK and JNK was investigated by Western blotting. Keratinocytes were primed with IL-1Ra for 1 h then stimulated with concentrated sweat obtained from volunteers for 6 h, the mRNA expression of IL-8, IL-1β, RIG-I, NOD2 (C), and CCL2 (E) was detected by real time PCR. Relative mRNA levels were expressed as means±SD (<i>n</i> = 3). *<i>p</i><0.05: compared to that of sweat stimulation without IL-1Ra. (D) Keratinocytes were primed with IL-1Ra for 1h then stimulated with concentrated sweat obtained from volunteers for 24 h, IL-8 secretion from cultures was detected by ELISA of supernatants. Concentrations represent means±SD (<i>n</i> = 3). *<i>p</i><0.05: compared to that of sweat stimulation without IL-1Ra.</p

IL-1α, IL-1β and IL-31 were quantified in the sweats obtained from volunteers.

<p>(A) Sweat samples obtained from 11 healthy volunteers were subjected to ELISA, and the concentrations of IL-1α, IL-1β and IL-31 were detected and quantified against the levels of total sweat protein, respectively. Concentrations (expressed as ng/mg sweat protein) represent means±SD (<i>n</i> = 11). (B) Immunohistochemistry showed the specific expression of IL-31 protein in eccrinne gland in normal skin. (a) The specific staining of IL-31 protein in the eccrine gland apparatus (original magnification: 40X) (b) IL-31 staining in eccrine gland and duct (original magnification: 200X) (c) IL-31 staining in eccrine gland and duct (original magnification: 400X) (d) the marked IL-31 staining in eccrine straight duct (original magnification: 400X) (e) the marked IL-31 staining in the coiled eccrine ducts (original magnification: 200X) (f) negative staining with mouse IgG and then nuclear staining with haematoxylin (original magnification: 40X) (small arrows indicate eccrine glands, and big arrows indicate eccrine ducts).</p