ΔNp63 regulates IL-33 and IL-31 signaling in atopic dermatitis

ΔNp63 regulates Sfrp1 expression to direct salivary gland branching morphogenesis

Branching morphogenesis is a complex process shared by many organs including the lungs, kidney, prostate, as well as several exocrine organs including the salivary, mammary and lacrimal glands. This critical developmental program ensures the expansion of an organ's surface area thereby maximizing processes of cellular secretion or absorption. It is guided by reciprocal signaling from the epithelial and mesenchymal cells. While signaling pathways driving salivary gland branching morphogenesis have been relatively well-studied, our understanding of the underlying transcriptional regulatory mechanisms directing this program, is limited. Here, we performed in vivo and ex vivo studies of the embryonic mouse submandibular gland to determine the function of the transcription factor ΔNp63, in directing branching morphogenesis. Our studies show that loss of ΔNp63 results in alterations in the differentiation program of the ductal cells which is accompanied by a dramatic reduction in branching morphogenesis that is mediated by dysregulation of WNT signaling. We show that ΔNp63 modulates WNT signaling to promote branching morphogenesis by directly regulating Sfrp1 expression. Collectively, our findings have revealed a novel role for ΔNp63 in the regulation of this critical process and offers a better understanding of the transcriptional networks involved in branching morphogenesis.

ΔNp63 Regulates Homeostasis, Stemness, and Suppression of Inflammation in the Adult Epidermis

The p63 transcription factor is critical for epidermis formation in embryonic development, but its role in the adult epidermis is poorly understood. In this study, we show that acute genetic ablation of ΔNp63, the main p63 isoform, in adult epidermis disrupts keratinocyte proliferation and self-maintenance and, unexpectedly, triggers an inflammatory psoriasis-like condition. Mechanistically, single-cell RNA sequencing revealed the downregulation of cell cycle genes, upregulation of differentiation markers, and induction of several proinflammatory pathways in ΔNp63-ablated keratinocytes. Intriguingly, ΔNp63-ablated cells disappear by 3 weeks after ablation, at the expense of the remaining nonablated cells. This is not associated with active cell death and is likely due to reduced self-maintenance and enhanced differentiation. Indeed, in vivo wound healing, a physiological readout of the epidermal stem cell function, is severely impaired upon ΔNp63 ablation. We found that the Wnt signaling pathway (Wnt10A, Fzd6, Fzd10) and the activator protein 1 (JunB, Fos, FosB) factors are the likely ΔNp63 effectors responsible for keratinocyte proliferation/stemness and suppression of differentiation, respectively, whereas IL-1a, IL-18, IL-24, and IL-36γ are the likely negative effectors responsible for suppression of inflammation. These data establish ΔNp63 as a critical node that coordinates epidermal homeostasis, stemness, and suppression of inflammation, upstream of known regulatory pathways.

Direct 3D Sampling of the Embryonic Mouse Head: Layer-wise Nanosecond Infrared Laser (NIRL) Ablation from Scalp to Cortex for Spatially Resolved Proteomics

Common workflows in bottom-up proteomics require homogenization of tissue samples to gain access to the biomolecules within the cells. The homogenized tissue samples often contain many different cell types, thereby representing an average of the natural proteome composition, and rare cell types are not sufficiently represented. To overcome this problem, small-volume sampling and spatial resolution are needed to maintain a better representation of the sample composition and their proteome signatures. Using nanosecond infrared laser ablation, the region of interest can be targeted in a three-dimensional (3D) fashion, whereby the spatial information is maintained during the simultaneous process of sampling and homogenization. In this study, we ablated 40 μm thick consecutive layers directly from the scalp through the cortex of embryonic mouse heads and analyzed them by subsequent bottom-up proteomics. Extra- and intracranial ablated layers showed distinct proteome profiles comprising expected cell-specific proteins. Additionally, known cortex markers like SOX2, KI67, NESTIN, and MAP2 showed a layer-specific spatial protein abundance distribution. We propose potential new marker proteins for cortex layers, such as MTA1 and NMRAL1. The obtained data confirm that the new 3D tissue sampling and homogenization method is well suited for investigating the spatial proteome signature of tissue samples in a layerwise manner. Characterization of the proteome composition of embryonic skin and bone structures, meninges, and cortex lamination in situ enables a better understanding of molecular mechanisms of development during embryogenesis and disease pathogenesis.

Neutrophil swarms containing myeloid-derived suppressor cells are crucial for limiting oral mucosal infection by C. albicans

Oral mucosal colonization by C. albicans (Ca) is benign in healthy people but progresses to deeper infection known as oropharyngeal candidiasis (OPC) that may become disseminated when combined with immunosuppression. Cortisone-induced immunosuppression is a well-known risk factor for OPC, however the mechanism by which it permits infection is poorly understood. Neutrophils are the primary early sentinels preventing invasive fungal growth, and here we identify that in vivo neutrophil functional complexes known as swarms are crucial for preventing Ca invasion which are disrupted by cortisone. Neutrophil swarm function required leukotriene B4 receptor 1 (BLT1) expression, and swarms were further characterized by peripheral association of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) showing that OPC recruits PMN-MDSCs to this site of infection. Furthermore, PMN-MDSCs associated with Ca hyphae had no direct antifungal effect but showed prolonged survival times and increased autophagy. Thus in vivo neutrophil swarms are complex structures with spatially associated PMN-MDSCs that likely contribute immunoregulatory functions to resolve OPC. These swarm structures have an important function in preventing deep invasion by Ca within the oral mucosa and represent a mechanism for increased disease severity under immune deficient clinical settings.

Orchestration of Mesenchymal Stem/Stromal Cells and Inflammation During Wound Healing

Wound healing is a complex process and encompasses a number of overlapping phases, during which coordinated inflammatory responses following tissue injury play dominant roles in triggering evolutionarily highly conserved principals governing tissue repair and regeneration. Among all nonimmune cells involved in the process, mesenchymal stem/stromal cells (MSCs) are most intensely investigated and have been shown to play fundamental roles in orchestrating wound healing and regeneration through interaction with the ordered inflammatory processes. Despite recent progress and encouraging results, an informed view of the scope of this evolutionarily conserved biological process requires a clear understanding of the dynamic interplay between MSCs and the immune systems in the process of wound healing. In this review, we outline current insights into the ways in which MSCs sense and modulate inflammation undergoing the process of wound healing, highlighting the central role of neutrophils, macrophages, and T cells during the interaction. We also draw attention to the specific effects of MSC-based therapy on different pathological wound healing. Finally, we discuss how ongoing scientific advances in MSCs could be efficiently translated into clinical strategies, focusing on the current limitations and gaps that remain to be overcome for achieving preferred functional tissue regeneration.

The Role of Tight Junctions in Atopic Dermatitis: A Systematic Review

BACKGROUND

Tight junctions are transmembrane proteins that regulate the permeability of water, solutes including ions, and water-soluble molecules. The objective of this systematic review is to focus on the current knowledge regarding the role of tight junctions in atopic dermatitis and the possible impact on their therapeutic potential.

METHODS

A literature search was performed in PubMed, Google Scholar, and Cochrane library between 2009 and 2022. After evaluation of the literature and taking into consideration their content, 55 articles were finally included.

RESULTS

TJs' role in atopic dermatitis extends from a microscopic scale to having macroscopic effects, such as increased susceptibility to pathogens and infections and worsening of atopic dermatitis features. Impaired TJ barrier function and skin permeability in AD lesions is correlated with cldn-1 levels. Th2 inflammation inhibits the expression of cldn-1 and cldn-23. Scratching has also been reported to decrease cldn-1 expression. Dysfunctional TJs' interaction with Langerhans cells could increase allergen penetration. Susceptibility to cutaneous infections in AD patients could also be affected by TJ cohesion.

CONCLUSIONS

Dysfunction of TJs and their components, especially claudins, have a significant role in the pathogenesis and vicious circle of inflammation in AD. Discovering more basic science data regarding TJ functionality may be the key for the use of specific/targeted therapies in order to improve epidermal barrier function in AD.

Safe and Effective Antioxidant: The Biological Mechanism and Potential Pathways of Ergothioneine in the Skin

Ergothioneine, a sulfur-containing micromolecular histidine derivative, has attracted increasing attention from scholars since it was confirmed in the human body. In the human body, ergothioneine is transported and accumulated specifically through OCTN-1, especially in the mitochondria and nucleus, suggesting that it can target damaged cells and tissues as an antioxidant. It shows excellent antioxidant, anti-inflammatory effects, and anti-aging properties, and inhibits melanin production. It is a mega antioxidant that may participate in the antioxidant network system and promote the reducing glutathione regeneration cycle. This review summarizes studies on the antioxidant effects of ergothioneine on various free radicals in vitro to date and systematically introduces its biological activities and potential mechanisms, mostly in dermatology. Additionally, the application of ergothioneine in cosmetics is briefly summarized. Lastly, we propose some problems that require solutions to understand the mechanism of action of ergothioneine. We believe that ergothioneine has good prospects in the food and cosmetics industries, and can thus meet some needs of the health and beauty industry.

ΔNp63 maintains the fidelity of the myoepithelial cell lineage and directs cell differentiation programs in the murine salivary gland

Salivary glands consist of several epithelial cell types of distinct lineages and functional characteristics that are established by directed differentiation programs of resident stem and progenitor cells. We have shown that ΔNp63, a crucial transcriptional regulator of stem/progenitor cells, is enriched in both the basal and myoepithelial cell (MEC) populations and that ΔNp63 positive cells maintain all the descendent epithelial cell lineages of the adult mouse salivary glands (mSGs). Although this pivotal role of ΔNp63 in driving the broader epithelial cell fate and identity in the mSG has been demonstrated, how ΔNp63 functions specifically in the commitment and differentiation of the MEC population is less understood. Using multiple genetic mouse models that allow for cell tracing, we show that ΔNp63 is critical in maintaining and renewing MECs, in part through the transcriptional regulation of Acta2 gene expression, a defining marker of this cell population. We demonstrate that during adult mSG homeostasis, ΔNp63 enriched MECs function as bipotent progenitor cells that maintain not only the MEC population, but also the distinctly different ductal cell lineages. The fidelity of this process is dependent on ΔNp63 expression, since MEC-specific ablation of ΔNp63 results in altered MEC differentiation and affects cellular plasticity resulting in aberrant differentiation of the intercalated ducts and acinar cells. In contrast, we find that the contribution of MECs to ductal and acinar cell regeneration following severe injury is independent of ΔNp63. Our observations offer new insights into cellular mechanisms driving MEC fate choices and differentiation programs in the context of salivary gland homeostasis and in response to injury and regeneration. Long term, these findings have implications for better treatment of salivary gland dysfunction through stem cell-based approaches.

Torilis japonica Extract Suppresses the Induction of Atopic Inflammation

As one of the major intractable allergic disorders, atopic inflammation is commonly accompanied by itching, dry skin, and inflammation. Atopic inflammation deteriorates the quality of life and has no fundamental cure, so it is crucial to urgently explore and develop natural resources for long-term treatment without any side effects. This study aimed to verify Torilis japonica extract (TJE)'s relieving effect and mechanism against atopic inflammation using skin cells and skin equivalent models, as well as to investigate torilin's effect (obtained from TJE) and other unknown components as marker compounds. Torilin concentration was verified in TJE using high-performance liquid chromatography and analyzed the unknown components using nuclear magnetic resonance spectroscopy. Furthermore, TJE's cytotoxicity, regenerative effect, and cell cycle regulation effects were confirmed using skin cells with atopic inflammation (human dermal fibroblasts and HaCaT keratinocytes) by using TNF-α and IFN-γ treatments. Consequently, TJE was demonstrated to regulate TARC and CTACK expressions as chemokines and those of interleukin-4, -5, and -13 as cytokines related to atopic inflammation. TJE was further confirmed to affect the matrix metalloproteinase-1, -2, and -9 expressions, which are essential in skin damage. Lastly, this study confirmed TJE's relieving effect against atopic inflammation through a 3D skin model and RhCE model using human dermal fibroblasts and HaCaT keratinocytes. These findings on atopic inflammation verified torilin's relieving effects and TJE's other components.

A Systemic and Integrated Analysis of p63-Driven Regulatory Networks in Mouse Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity and is linked to tobacco exposure, alcohol consumption, and human papillomavirus infection. Despite therapeutic advances, a lack of molecular understanding of disease etiology, and delayed diagnoses continue to negatively affect survival. The identification of oncogenic drivers and prognostic biomarkers by leveraging bulk and single-cell RNA-sequencing datasets of OSCC can lead to more targeted therapies and improved patient outcomes. However, the generation, analysis, and continued utilization of additional genetic and genomic tools are warranted. Tobacco-induced OSCC can be modeled in mice via 4-nitroquinoline 1-oxide (4NQO), which generates a spectrum of neoplastic lesions mimicking human OSCC and upregulates the oncogenic master transcription factor p63. Here, we molecularly characterized established mouse 4NQO treatment-derived OSCC cell lines and utilized RNA and chromatin immunoprecipitation-sequencing to uncover the global p63 gene regulatory and signaling network. We integrated our p63 datasets with published bulk and single-cell RNA-sequencing of mouse 4NQO-treated tongue and esophageal tumors, respectively, to generate a p63-driven gene signature that sheds new light on the role of p63 in murine OSCC. Our analyses reveal known and novel players, such as COTL1, that are regulated by p63 and influence various oncogenic processes, including metastasis. The identification of new sets of potential biomarkers and pathways, some of which are functionally conserved in human OSCC and can prognosticate patient survival, offers new avenues for future mechanistic studies.

Identification of novel candidate genes and predicted miRNAs in atopic dermatitis patients by bioinformatic methods

Atopic dermatitis (AD) is a common, chronic inflammatory dermatosis with relapsing eruptions. Our study used bioinformatics to find novel candidate differentially expressed genes (DEGs) and predicted miRNAs between AD patients and healthy controls. The Mesh term "atopic dermatitis" was retrieved to obtain DEGs in GEO datasets. DEGs between AD patients and healthy controls were analyzed using GEO2R. Overlapping DEGs between different datasets were obtained with use of Draw Venn software. GO and KEGG enrichment analyses were conducted by the use of DAVID. STRING and miRWalk were used to individually analyze PPI networks, interactions of candidate genes and predicted miRNAs. A total of 571 skin samples, as retrieved from 9 databases were assessed. There were 225 overlapping DEGs between lesioned skin samples of AD patients and that of healthy controls. Nineteen nodes and 160 edges were found in the largest PPI cluster, consisting of 17 up-regulated and 2 down-regulated nodes. Two KEGG pathways were identified, including the cell cycle (CCNB1, CHEK1, BUB1B, MCM5) and p53 (CCNB1, CHEK1, GTSE1) pathways. There were 56 nodes and 100 edges obtained in the miRNA-target gene network, with has-miR-17-5p targeted to 4 genes and has-miR-106b-5p targeted to 3 genes. While these findings will require further verification as achieved with experiments involving in vivo and in vitro modles, these results provided some initial insights into dysfunctional inflammatory and immune responses associated with AD. Such information offers the potential to develop novel therapeutic targets for use in preventing and treating AD.

The Developmental Transcription Factor p63 Is Redeployed to Drive Allergic Skin Inflammation through Phosphorylation by p38α

Keratinocytes, the epithelial cells of the skin, reprogram their gene expression and produce immune effector molecules when exposed to environmental and endogenous triggers of inflammation. It remains unclear how keratinocytes process physiological signals generated during skin irritation and switch from a homeostatic to an inflammatory state. In this article, we show that the stress-activated protein kinase p38α is crucial for keratinocytes to prompt changes in their transcriptome upon cytokine stimulation and drive inflammation in allergen-exposed skin. p38α serves this function by phosphorylating p63, a transcription factor essential for the lineage identity and stemness of the skin epithelium. Phosphorylation by p38α alters the activity of p63 and redeploys this developmental transcription factor to a gene expression program linked to inflammation. Genetic ablation and pharmacological inhibition of p38α or the p38α-p63 target gene product MMP13 attenuate atopic dermatitis-like disease in mice. Our study reveals an epithelial molecular pathway promoting skin inflammation and actionable through treatment with topical small-molecule therapeutics.

Soy diet induces intestinal inflammation in adult Zebrafish: Role of OTX and P53 family

Inflammatory bowel diseases (IBDs) are a group of inflammatory conditions of the colon and small intestine, including Crohn's disease and ulcerative colitis. Since Danio rerio is a promising animal model to study gut function, we developed a soy-dependent model of intestinal inflammation in adult zebrafish. The soya bean meal diet was given for 4 weeks and induced an inflammatory process, as demonstrated by morphological changes together with an increased percentage of neutrophils infiltrating the intestinal wall, which developed between the second and fourth week of treatment. Pro-inflammatory genes such as interleukin-1beta, interleukin-8 and tumour necrosis factor alpha were upregulated in the second week and anti-inflammatory genes such as transforming growth factor beta and interleukin-10. Interestingly, an additional expression peak was found for interleukin-8 at the fourth week. Neuronal genes, OTX1 and OTX2, were significantly upregulated in the first two  weeks, compatible with the development of the changes in the gut wall. As for the genes of the p53 family such as p53, DNp63 and p73, a statistically significant increase was observed after two weeks of treatment compared with controls. Interestingly, DNp63 and p73 were shown an additional peak after four weeks. Our data demonstrate that soya bean meal diet negatively influences intestinal morphology and immunological function in adult zebrafish showing the features of acute inflammation. Data observed at the fourth week of treatment may suggest initiation of chronic inflammation. Adult zebrafish may represent a promising model to better understand the mechanisms of food-dependent intestinal inflammation.

Sarsasapogenin and fluticasone combination improves DNFB induced atopic dermatitis lesions in BALB/c mice

OBJECTIVE

Atopic dermatitis (AD) is a pruritic, chronic, relapsing inflammatory skin disease. The research aims to study the effects of Sarsasapogenin and its combination with Fluticasone in 2, 4-Dinitrofluorobenzene (DNFB) induced atopic dermatitis in BALB/c mice.

MATERIAL AND METHODS

Thirty male Balb/c mice were divided into 5 groups: (i) Normal control (NC), (ii) Disease control (DNFB), (iii) Sarsasapogenin (SG) (50 µg/mice), (iv) Fluticasone (FC) (50 µg/mice), (v) Sarsasapogenin + Fluticasone (SG + FC) combination (25 µg/mice). Dermatitis was induced by repeated application of DNFB in Balb/c mice. On topical application of SG, FC, and SG + FC combination on the ear and skin lesions, body weight, ear weight, ear thickness, erythema score, spleen weight, cytokines, immunoglobulin E (IgE) levels, nitric oxide (NO) level, hematological parameters, and oxidative stress markers were evaluated. Histological analysis of the ear tissue was also done.

RESULTS

The results stated that SG and SG + FC treatment to mice considerably decrease the ear weight, ear thickness, spleen weight, serum IgE, cytokines, NO levels, and restoration of antioxidant stress markers with elevation in the hematological parameters. The observations were further confirmed by histopathological analysis of ear tissue.

CONCLUSION

These data specify that SG has been demonstrated as a probable therapy for the treatment of allergic skin diseases in combination with FC by decreasing its dose from 50 to 25 µg/mice to avoid the chronic side effects of FC. Hence, it can be concluded that SG and SG + FC combination significantly improved the AD-like symptoms in the DNFB sensitized mice through mitigating the production of proinflammatory mediators and restoration of oxidative stress markers.

Keratinocytes: innate immune cells in atopic dermatitis

The skin is a unique immune organ that constitutes a complex network of physical, chemical and microbiological barriers against external insults. Keratinocytes are the most abundant cell type in the epidermis. These cells form the physical skin barrier and represent the first line of the host defense system by sensing pathogens via innate immune receptors, initiating anti-microbial responses and producing various cytokines, chemokines and anti-microbial peptides, which are important events in immunity. A damaged epidermal barrier in atopic dermatitis allows the penetration of potential allergens and pathogens to activate keratinocytes. Among the dysregulation of immune responses in atopic dermatitis, activated keratinocytes play a role in several biological processes that contribute to the pathogenesis of atopic dermatitis. In this review, we summarize the current understanding of the innate immune functions of keratinocytes in the pathogenesis of atopic dermatitis, with a special emphasis on skin-derived anti-microbial peptides and atopic dermatitis-related cytokines and chemokines in keratinocytes. An improved understanding of the innate immunity mediated by keratinocytes can provide helpful insight into the pathophysiological processes of atopic dermatitis and support new therapeutic efforts.

Dysregulated skin barrier function in Tmem79 mutant mice promotes IL-17A-dependent spontaneous skin and lung inflammation

BACKGROUND

Atopic dermatitis (AD) is associated with a dysregulation of the skin barrier and may predispose to the development of secondary allergic conditions, such as asthma. Tmem79^ma/ma mice harbor a mutation in the gene encoding Transmembrane Protein 79 (or Mattrin), which has previously been associated with AD. As a result of the Tmem79 gene mutation, these mice have a defective skin barrier and develop spontaneous skin inflammation. In this study, Tmem79^ma/ma mice were assessed for the underlying immunological response in the development of spontaneous skin and lung inflammation.

METHODS

Development of spontaneous skin and lung inflammation in Tmem79^ma/ma mice was analyzed. We further investigated susceptibility to cutaneous Staphylococcus aureus infection. Tmem79^ma/ma were crossed to IL-17A-deficient mice to address the contribution of IL-17A to spontaneous skin and lung disease.

RESULTS

Tmem79^ma/ma mice developed IL-17A-dependent spontaneous AD-like inflammation and were refractory to S aureus infection. Mutant mice progressed to airway inflammation subsequent to the occurrence of dermatitis. The progression from skin to lung disease is dependent on adaptive immunity and is facilitated by cutaneous expansion of Th17 and TCRγδ T cells.

CONCLUSION

Mice lacking Tmem79/Mattrin expression have a defective skin barrier. In adulthood, these mice develop dermatitis with secondary progression to lung inflammation. The development of skin and lung inflammation is IL-17A-dependent and mediated by TCRγδ T cells.

p-coumaric acid, an active ingredient of Panax ginseng, ameliolates atopic dermatitis-like skin lesions through inhibition of thymic stromal lymphopoietin in mice

Background

Atopic dermatitis (AD) is associated with chronic skin inflammatory reactions. p-coumaric acid (pCA) is an active ingredient of Panax ginseng Meyer (Araliaceae).

Methods

Here, we estimated an anti-AD effect of pCA on activated mast cells, activated splenocytes, and a mouse model of AD. Cytokines levels were measured by ELISA and protein activation was analyzed by Western blotting. 2,4-dinitrofluorobenzene (DNFB) was used to induce AD-like skin lesions.

Results

The treatment with pCA suppressed the productions and mRNA expressions of thymic stromal lymphopoietin (TSLP), TNF-ɑ, IL-6, and IL-1β in HMC-1 cells. pCA downregulated the expressions of RIP2 and caspase-1, phosphorylated-(p)p38/pJNK/pERK, and pIKKβ/pIkBɑ/NF-κB in HMC-1 cells. pCA also decreased the productions of TSLP, TNF-ɑ, IL-6, IL-4, and IFN-γ in the supernatant of stimulated splenic cells. Comparing to DNFB-sensitized control group, pCA-treated group alleviated pathological changes of AD-like lesions. pCA decreased the proteins and mRNA expressions levels of TSLP, IL-6, and IL-4 in the skin lesions. Caspase-1 activation was also downregulated by pCA treatment in the AD-like lesions. The serum levels of histamine, IgE, TSLP, TNF-ɑ, IL-6, and IL-4 were suppressed following treatment with pCA.

Conclusion

This study suggests that pCA has the potential to improve AD by suppressing TSLP as well as inflammatory cytokines via blocking of caspase-1/NF-κB signal cascade.

A human embryonic stem cell-based in vitro model revealed that ultrafine carbon particles may cause skin inflammation and psoriasis

Air pollution has been linked to many health issues, including skin conditions, especially in children. Among all the atmospheric pollutants, ultrafine particles have been deemed very dangerous since they can readily penetrate the lungs and skin, and be absorbed into the bloodstream. Here, we employed a human embryonic stem cell (hESC)-based differentiation system towards keratinocytes, to test the effects of ultrafine carbon particles, which mimic ambient ultrafine particles, at environment related concentrations. We found that 10 ng/mL to 10 μg/mL ultrafine carbon particles down-regulated the expression of the pluripotency marker SOX2 in hESCs. Moreover, 1 μg/mL to 10 μg/mL carbon particle treatments disrupted the keratinocyte differentiation, and up-regulated inflammation- and psoriasis-related genes, such as IL-1β, IL-6, CXCL1, CXCL2, CXCL3, CCL20, CXCL8, and S100A7 and S100A9, respectively. Overall, our results provide a new insight into the potential developmental toxicity of atmospheric ultrafine particles.

Myoblasts rely on TAp63 to control basal mitochondria respiration

p53, with its family members p63 and p73, have been shown to promote myoblast differentiation by regulation of the function of the retinoblastoma protein and by direct activation of p21^Cip/Waf1 and p57^Kip2, promoting cell cycle exit. In previous studies, we have demonstrated that the TAp63γ isoform is the only member of the p53 family that accumulates during in vitro myoblasts differentiation, and that its silencing led to delay in myotube fusion. To better dissect the role of TAp63γ in myoblast physiology, we have generated both sh-p63 and Tet-On inducible TAp63γ clones. Gene array analysis of sh-p63 C2C7 clones showed a significant modulation of genes involved in proliferation and cellular metabolism. Indeed, we found that sh-p63 C2C7 myoblasts present a higher proliferation rate and that, conversely, TAp63γ ectopic expression decreases myoblasts proliferation, indicating that TAp63γ specifically contributes to myoblasts proliferation, independently of p53 and p73. In addition, sh-p63 cells have a defect in mitochondria respiration highlighted by a reduction in spare respiratory capacity and a decrease in complex I, IV protein levels. These results demonstrated that, beside contributing to cell cycle exit, TAp63γ participates to myoblasts metabolism control.

Potential role of TP63 in apical periodontitis development

AIM

To investigate the expression of TP63 in apical periodontitis (AP) tissues and the association of single nucleotide polymorphisms (SNPs) in the TP63 gene with AP using a case-control dataset.

METHODOLOGY

Expression of TP63 in human AP lesions (apical abscess, radicular cyst, periapical granuloma) was evaluated using immunohistochemistry. A case-control association study was performed to assess the association of TP63 polymorphisms in individuals having AP with or without associated pain. Cases were defined as subjects with deep caries and AP (n = 151) and subjects with symptomatic apical periodontitis or acute apical abscess (n = 124). Subjects without AP (n = 169) and asymptomatic (n = 196) were used as controls, respectively. Saliva samples were collected as source of genomic DNA. Twelve SNPs in the TP63 gene were selected for genotyping using Taqman chemistry in real-time PCR. Data analysis was performed using PLINK software. The Bonferroni method was applied to correct for multiple testing; α ≤ 0.004 indicates significant differences between groups.

RESULTS

TP63 expression was evident in apical abscesses and radicular cysts, while weaker expression was observed in periapical granulomas. Positive expression was observed in mononuclear cells in the granulation tissues of all AP lesions. Regarding the presence of AP, a trend for allelic association was observed for rs16864812 and rs9810322 (P = 0.04) and rs9810322 genotypes were also nominally associated with AP under a dominant model (P = 0.04). When considering the presence of periapical pain, a trend for allelic and genotypic association was observed for rs10155037 (P = 0.03). Haplotypes were also associated with AP and periapical pain (P ≤ 0.05).

CONCLUSIONS

Apical periodontitis is a complex multifactorial condition and it is likely that multiple genes and environmental effects may influence its susceptibility, progression or both. TP63 variants may play a role in AP pathogenesis and susceptibility, individually or interactively with other genes. Additional studies in other populations and functional studies are needed to improve understanding of the role of TP63 in AP.

Use of Physcion to Improve Atopic Dermatitis-Like Skin Lesions through Blocking of Thymic Stromal Lymphopoietin

Physcion is well known for the treatment of carcinoma. However, the therapeutic effect of physcion on atopic dermatitis (AD) through the inhibition of thymic stromal lymphopoietin (TSLP) level remains largely unknown. In this study, we investigated the anti-AD effect of physcion using HMC-1 cells, splenocytes, and a murine model. Treatment with physcion decreased production and mRNA expression levels of TSLP, IL-6, TNF-ɑ, and IL-1β in activated HMC-1 cells. Physcion reduced the expression levels of RIP2/caspase-1 and phospho (p)ERK/pJNK/pp38 in activated HMC-1 cells. Physcion suppressed the expression levels of pIKKβ/NF-κB/pIkB in activated HMC-1 cells. Moreover, physcion attenuated the production levels of TSLP, IL-4, IL-6, TNF-, and IFN-γ from activated splenocytes. Oral administration of physcion improved the severity of 2,4-dinitrochlorobenzene-induced AD-like lesional skin through reducing infiltration of inflammatory cells and mast cells, and the protein and mRNA levels of TSLP, IL-4, and IL-6 in the lesional skin tissues. Physcion attenuated histamine, IgE, TSLP, IL-4, IL-6, and TNF- levels in serum. In addition, physcion inhibited caspase-1 activation in the lesional skin tissues. These findings indicate that physcion could ameliorate AD-like skin lesions by inhibiting TSLP levels via caspase-1/MAPKs/NF-kB signalings, which would provide experimental evidence of the therapeutic potential of physcion for AD.

Differential bronchial epithelial response regulated by ΔNp63: a functional understanding of the epithelial shedding found in asthma

Bronchial epithelial cells serve as a physical barrier at the forefront of the immune system. Barrier disruption and an excessive immune response of the bronchial epithelium contribute to the pathophysiology of asthma, a chronic bronchial inflammatory disease. The purpose of this study was to investigate the functional significance of ΔNp63, a p53-like transcription factor expressed by the basal bronchial epithelium. The immunohistochemical expression profile of ΔNp63 was evaluated in human bronchial tissue derived from asthma patients. The role of ΔNp63 in apoptosis inhibition and production of soluble mediators was investigated in vitro with cultured BEAS-2B bronchial epithelial cells using molecular biological analysis. In healthy bronchial tissue, ΔNp63-positive basal epithelial cells were covered with differentiated ΔNp63-negative cells but in the asthmatic airway, ΔNp63-positive cells were directly exposed to the bronchial lumen due to severe epithelial shedding. ΔNp63 regulated bronchial apoptosis in response to Toll-like receptor 3 stimulation. On the other hand, expression of ΔNp63 was modulated by stimulation with trypsin and SLIGKV, protease-activated receptor 2 ligands. Further phenotypic analysis revealed that ΔNp63 controlled the transcriptional expression and protein release of some epithelium-derived proinflammatory cytokines and endogenous protease inhibitors. We conclude that ΔNp63 modulates the bronchial epithelial response to viral infection. At the same time, ΔNp63 expression is influenced by proteases, which are abundant in house dust mites. Therefore, the ΔNp63 axis would be intimately involved in these two major triggers of asthma exacerbations, viral infection and protease overload.

Genetic and scRNA-seq Analysis Reveals Distinct Cell Populations that Contribute to Salivary Gland Development and Maintenance

Stem and progenitor cells of the submandibular salivary gland (SMG) give rise to, maintain, and regenerate the multiple lineages of mature epithelial cells including those belonging to the ductal, acinar, basal and myoepithelial subtypes. Here we have exploited single cell RNA-sequencing and in vivo genetic lineage tracing technologies to generate a detailed map of the cell fate trajectories and branch points of the basal and myoepithelial cell populations of the mouse SMG during embryonic development and in adults. Our studies show that the transcription factor p63 and alpha-smooth muscle actin (SMA) serve as faithful markers of the basal and myoepithelial cell lineages, respectively and that both cell types are endowed with progenitor cell properties. However, p63⁺ basal and SMA⁺ myoepithelial cells exhibit distinct cell fates by virtue of maintaining different cellular lineages during morphogenesis and in adults. Collectively, our results reveal the dynamic and complex nature of the diverse SMG cell populations and highlight the distinct differentiation potential of the p63 and SMA expressing subtypes in the stem and progenitor cell hierarchy. Long term these findings have profound implications towards a better understanding of the molecular mechanisms that dictate lineage commitment and differentiation programs during development and adult gland maintenance.

IL-33/IL-31 Axis: A Potential Inflammatory Pathway

Cytokines play an important role in the regulation of the immune system (adaptive and innate). Given their importance in proinflammatory processes, cytokines have been used for understanding the pathogenesis and as biomarkers in many diseases. IL-31 and IL-33 are still considered novel cytokines. IL-31 controls signalling and regulates a huge amount of biological functions: it induces proinflammatory cytokines, regulates cell proliferation, and is involved also in tissue remodelling. On the other hand, IL-33 has been identified as an “alarmin” released from the epithelial cells and from different human tissues and organs after a damage following, that is, an inflammatory process. The aim of this literature review is to strengthen the hypothesis about an IL-31/IL-33 axis by evaluating the most recent studies linking these two cytokines. Literature data showed that, in many cases, IL-31 and IL-33 are linked to each other and that their expression is correlated with disease severity. The presence of one interleukin might stimulate the induction of the other, amplifying inflammation and the consequent detrimental processes. In a near future, influencing their balance could be helpful in modulating the first responses of the immune system in order to prevent the development of many inflammation-related diseases.

p63 is a key regulator of iRHOM2 signalling in the keratinocyte stress response

Hyperproliferative keratinocytes induced by trauma, hyperkeratosis and/or inflammation display molecular signatures similar to those of palmoplantar epidermis. Inherited gain-of-function mutations in RHBDF2 (encoding iRHOM2) are associated with a hyperproliferative palmoplantar keratoderma and squamous oesophageal cancer syndrome (termed TOC). In contrast, genetic ablation of rhbdf2 in mice leads to a thinning of the mammalian footpad, and reduces keratinocyte hyperproliferation and migration. Here, we report that iRHOM2 is a novel target gene of p63 and that both p63 and iRHOM2 differentially regulate cellular stress-associated signalling pathways in normal and hyperproliferative keratinocytes. We demonstrate that p63-iRHOM2 regulates cell survival and response to oxidative stress via modulation of SURVIVIN and Cytoglobin, respectively. Furthermore, the antioxidant compound Sulforaphane downregulates p63-iRHOM2 expression, leading to reduced proliferation, inflammation, survival and ROS production. These findings elucidate a novel p63-associated pathway that identifies iRHOM2 modulation as a potential therapeutic target to treat hyperproliferative skin disease and neoplasia.

A double dealing tale of p63: an oncogene or a tumor suppressor

As a member of tumor suppressor p53 family, p63, a gene encoding versatile protein variant, has been documented to correlate with cancer formation and progression, though it is rarely mutated in cancer patients. However, it has long been controversial on whether p63 is an oncogene or a tumor suppressor. Here, we comprehensively reviewed reports on roles of p63 in development, tumorigenesis and tumor progression. According to data from molecular cell biology, genetic models and clinic research, we conclude that p63 may act as either an oncogene or a tumor suppressor gene in different scenarios: TA isoforms of p63 gene are generally tumor-suppressive through repressing cell proliferation, survival and metastasis; ΔN isoforms, however, may initiate tumorigenesis via promoting cell proliferation and survival, but inhibit tumor metastasis and progression; effects of p63 on tumor formation and progression depend on the context of the whole p53 family, and either amplification or loss of p63 gene locus can break the balance to cause tumorigenesis.

Functional characterization and genomic studies of a novel murine submandibular gland epithelial cell line

A better understanding of the normal and diseased biology of salivary glands (SG) has been hampered, in part, due to difficulties in cultivating and maintaining salivary epithelial cells. Towards this end, we have generated a mouse salivary gland epithelial cell (mSGc) culture system that is well-suited for the molecular characterization of SG cells and their differentiation program. We demonstrate that mSGc can be maintained for multiple passages without a loss of proliferation potential, readily form 3D-spheroids and importantly express a panel of well-established salivary gland epithelial cell markers. Moreover, mSGc 3D-spheroids also exhibit functional maturation as evident by robust agonist-induced intracellular calcium signaling. Finally, transcriptomic characterization of mSGc by RNA-seq and hierarchical clustering analysis with adult organ RNA-seq datasets reveal that mSGc retain most of the molecular attributes of adult mouse salivary gland. This well-characterized mouse salivary gland cell line will fill a critical void in the field by offering a valuable resource to examine various mechanistic aspects of mouse salivary gland biology.

Integrin-β4 is a novel transcriptional target of TAp73

As a member of p53 family, p73 has attracted intense investigations due to its structural and functional similarities to p53. Among more than ten p73 variants, the transactivation (TA) domain-containing isoform TAp73 is the one that imitates the p53's behavior most. TAp73 induces apoptosis and cell cycle arrest, which endows it the capacity of tumour suppression. Also, it can exert diverse biological influences on cells through activating a complex and context dependent transcriptional programme. The transcriptional activities further broaden its roles in more intricate biological processes. In this article, we report that p73 is a positive regulator of a cell adhesion related gene named integrin β4 (ITGB4). This finding may have implications for the dissection of the biological mechanisms underlining p73 functions.

The role of toll-like receptor 3 in chronic contact hypersensitivity induced by repeated elicitation

BACKGROUND

Accumulating evidence suggests that Toll-like receptor (TLR)-3 signaling is involved in non-infectious immune and inflammatory reactions as well as in viral infections. The skin of patients with atopic dermatitis (AD) is often infected with virus and bacteria, leading to the aggravation of atopic symptoms. These findings suggest TLR3 signaling may be involved in the pathogenesis of AD, but the exact role of TLR3 in AD remains to be defined.

OBJECTIVE

The purpose of this study was to investigate the role of TLR3 in chronic contact hypersensitivity reactions induced by repeated elicitation, resembling the features of AD.

METHODS

Wild-type (WT) and Toll-like receptor 3 knockout (Tlr3 KO) mice were sensitized, and chronic contact hypersensitivity reactions were elicited in their ear skin via repeated application of a hapten, 2,4,6-trinitro-1-chlorobenzene (TNCB) or oxazolone.

RESULTS

The Tlr3 KO mice exhibited less ear swelling, less leukocyte infiltration into the skin, and lower serum total IgE levels than WT mice after hapten challenge. The Tlr3 KO mice also displayed lower expression levels of inflammatory cytokines (interleukin (IL)-33, IL-4, IL-10, and interferon-ɤ in their TNCB-treated ear skin than WT mice.

CONCLUSION

These results showed that TLR3 deficiency suppressed the development of chronic contact hypersensitivity reactions, suggesting that TLR3 signaling may participate in the pathogenesis of AD.

Expression of IL-22 in the Skin Causes Th2-Biased Immunity, Epidermal Barrier Dysfunction, and Pruritus via Stimulating Epithelial Th2 Cytokines and the GRP Pathway

Increased expression of Th22 cytokine IL-22 is a characteristic finding in atopic dermatitis (AD). However, the specific role of IL-22 in the pathogenesis of AD in vivo has yet to be elucidated. Consistent with observations in human AD, IL-22 was significantly increased in the AD skin of mice after epicutaneous sensitization to house dust mite allergen. Utilizing a skin-specific inducible transgenic system, we show in the present study that expression of IL-22 in the skin of mice caused an AD-like phenotype characterized by chronic pruritic dermatitis associated with Th2-biased local and systemic immune responses, downregulation of epidermal differentiation complex genes, and enhanced dermatitis upon epicutaneous allergen exposure. IL-22 potently induced the expression of gastrin-releasing peptide (GRP), a neuropeptide pruritogen, in dermal immune cells and sensory afferents and in their skin-innervating sensory neurons. IL-22 also differentially upregulated the expression of GRP receptor (GRPR) on keratinocytes of AD skin. The number of GRP+ cells in the skin correlated with the AD severity and the intensity of pruritus. IL-22 directly upregulated the expression of epithelial-derived type 2 cytokines (thymic stromal lymphopoietin and IL-33) and GRP in primary keratinocytes. Furthermore, GRP not only strongly induced thymic stromal lymphopoietin but it also increased the expression of IL-33 and GRPR synergistically with IL-22. Importantly, we found that the expression of GRP was strikingly increased in the skin of patients with AD. These results indicate that IL-22 plays important pathogenic roles in the initiation and development of AD, in part through inducing keratinocyte production of type 2 cytokines and activation of the GRP/GRPR pathway.

Atopic Eczema: Genetic Associations and Potential Links to Developmental Exposures

Atopic eczema (AE), or atopic dermatitis (AD), is a common inflammatory skin disease with a disrupted epidermal barrier and an allergic immune response. AD/AE is prominently characterized by a symptomatic itch and transient skin lesions. Infants compose a significant percentage affected. Two models have been proposed to explain AD/AE skin pathology: the gut microbiome-focused inside-outside model and the outside-inside model concentrating on the disrupted skin barrier/skin microbiome. Gene disruptions contributing to epidermal structure, as well as those in immune system genes, are implicated. Over 30 genes have been linked to AD/AE with Flg and Tmem79/Matt alterations being common. Other linked disruptions are in the interleukin-1 family of cytokines/receptors and the TH2 gene family of cytokines. Inheritable epigenetic modifications of the genes or associated proteins may also be involved. Skin barrier disruption and the allergic immune response have been the main foci in mechanistic studies of AD/AE, but the role of the environment is becoming more apparent. Thus, an examination of in utero exposures could be very helpful in understanding the heterogeneity of AD/AE. Although research is limited, there is evidence that developmental exposure to environmental tobacco smoke or phthalates may impact disease. Management for AD/AE includes topical corticosteroids and calcineurin inhibitors, which safely facilitate improvements in select individuals. Disease heterogeneity warrants continued research not only into elucidating disease mechanism(s), via identification of contributing genetic alterations, but also research to understand how/when these genetic alterations occur. This may lead to the cure that those affected by AD/AE eagerly await.