Ectodysplasin A Pathway Contributes to Human and Murine Skin Repair

Depletion of G9A attenuates imiquimod-induced psoriatic dermatitis via targeting EDAR-NF-κB signaling in keratinocyte

Psoriasis is a common and recurrent inflammatory skin disease characterized by inflammatory cells infiltration of the dermis and excessive proliferation, reduced apoptosis, and abnormal keratosis of the epidermis. In this study, we found that G9A, an important methyltransferase that mainly mediates the mono-methylation (me1) and di-methylation (me2) of histone 3 lysine 9 (H3K9), is highly expressed in lesions of patients with psoriasis and imiquimod (IMQ)-induced psoriasis-like mouse model. Previous studies have shown that G9A is involved in the pathogenesis of various tumors by regulating apoptosis, proliferation, differentiation, and invasion. However, the role of G9A in skin inflammatory diseases such as psoriasis remains unclear. Our data so far suggest that topical administration of G9A inhibitor BIX01294 as well as keratinocyte-specific deletion of G9A greatly alleviated IMQ-induced psoriatic alterations in mice for the first time. Mechanistically, the loss function of G9A causes the downregulation of Ectodysplasin A receptor (EDAR), consequently inhibiting the activation of NF-κB pathway, resulting in impaired proliferation and increased apoptosis of keratinocytes, therefore ameliorating the psoriatic dermatitis induced by IMQ. In total, we show that inhibition of G9A improves psoriatic-like dermatitis mainly by regulating cell proliferation and apoptosis rather than inflammatory processes, and that this molecule may be considered as a potential therapeutic target for keratinocyte hyperproliferative diseases such as psoriasis.

The Role of Ectodysplasin A on the Ocular Surface Homeostasis

Ectodysplasin A (EDA), a ligand of the TNF family, plays an important role in maintaining the homeostasis of the ocular surface. EDA is necessary for the development of the meibomian gland, the lacrimal gland, as well as the proliferation and barrier function of the corneal epithelium. The mutation of EDA can induce the destruction of the ocular surface resulting in keratopathy, abnormality of the meibomian gland and maturation of the lacrimal gland. Experimental animal studies showed that a prenatal ultrasound-guided intra-amniotic injection or postnatal intravenous administration of soluble recombinant EDA protein can efficiently prevent the development of ocular surface abnormalities in EDA mutant animals. Furthermore, local application of EDA could restore the damaged ocular surface to some extent. Hence, a recombinant EDA-based therapy may serve as a novel paradigm to treat ocular surface disorders, such as meibomian gland dysfunction and corneal epithelium abnormalities.

Ectodysplasin-A mRNA in exosomes released from activated hepatic stellate cells stimulates macrophage response

INTRODUCTION

The interaction between activated hepatic stellate cells (aHSCs) and macrophages is central to liver fibrosis development. The cargo contained within aHSC exosomes (aHSC-EXOs) and how aHSC-EXOs affect macrophage function is poorly understood.

METHODS

RNA from aHSC-EXOs was separated into small (<200-basepairs) and large (≥200-basepairs) RNA species, transfected into macrophages, and macrophage IL-6 and TNFα mRNA expression and protein secretion measured. Next generation sequencing was performed on EXOs from rat quiescent and aHSCs and human aHSCs. aHSCs were transfected with siRNA against ectodysplasin-A (EDA), EXOs collected, and their effect on macrophage function analyzed. Human cirrhotic liver was analyzed for EDA mRNA expression and compared to non-tumor liver (NTL).

RESULTS

Transfection with large RNA from aHSC-EXOs stimulated macrophage IL-6 and TNFα mRNA expression and protein secretion. EDA mRNA was highly expressed in aHSCs and transfection of aHSCs with EDA-siRNA decreased aHSC-EXO EDA mRNA and blunted the effect of aHSC-EXOs on macrophage function (IL-6/TNFα expression and macrophage migration). Human cirrhotic liver exhibited high EDA mRNA compared to NTL.

CONCLUSIONS

HSC activation leads to altered EXO mRNA/miRNA profiles with aHSC-EXOs mRNAs exerting a dominant role in altering macrophage function. Ectodysplasin-A mRNA is an important component in aHSC-EXOs in regulating macrophage function.

Profound gene expression changes in the epithelial monolayer of active ulcerative colitis and Crohn's disease

In recent years it has become apparent that the epithelium is highly involved in inflammatory bowel disease (IBD) pathophysiology. The majority of gene expression studies of IBD are generated from heterogeneous biopsies, providing no distinction between immune cells, the epithelium and other mucosal cells. By using laser capture microdissection (LCM) coupled with RNA sequencing, we aimed to characterize the expressional changes of the isolated colonic epithelial monolayer from ulcerative colitis (UC) and Crohn’s disease (CD) patients compared to healthy controls (HC). The analysis identified 3706 genes as differentially expressed between active IBD epithelium and HC. Weighted gene co-expression network analysis was used to stratify genes into modules, which were subsequently characterized using enrichment analysis. Our data show a distinct upregulation of the antigen presentation machinery during inflammation, including major histocompatibility complex class II molecules (e.g. HLA-DPA1, HLA-DPB1, HLA-DRA) and key transcription factors/activators (STAT1, IRF1, CIITA). We also see an epithelial downregulation of retinoic acid-responsive nuclear receptors (RARA, RARB, RXRA), but upregulation of retinoid-metabolizing enzymes (RDH11, ALDH1A2, ALDH1A3), which together suggest a perturbation of epithelial vitamin A signaling during active IBD. Lastly, we identified a cluster of stress-related genes, including activator protein 1 components JUNB and ATF3, as significantly upregulated in active UC but not in CD, revealing an interesting aspect of IBD heterogeneity. The results represent a unique resource for enhanced understanding of epithelial involvement in IBD inflammation and is a valuable tool for further studies on these processes.

EDA and EDAR expression at different stages of hair follicle development in cashmere goats and effects on expression of related genes

This study is focused on the detection of ectodysplasin A (EDA) and ectodysplasin A receptor (EDAR) mRNA expression levels and protein positions in seven stages of cashmere goat fetus development (45, 55, 65, 75 95, 115, and 135 d), with the main goal of investigating the effect of EDA and EDAR on genes related to hair follicle development. Quantitative real-time polymerase chain reaction (RT-qPCR) was used to measure EDA and EDAR expression levels in seven stages of cashmere goat fetus development. Immunohistochemistry (IHC) was used to locate EDA and EDAR in the critical stage of fetal hair follicle development (45–135 d). EDA and EDAR expression in fetal fibroblasts and epithelial cells was interfered with by short hairpin RNA (sh-RNA). The results indicated that EDA and EDAR were both expressed in the skin tissue in the seven cashmere goat embryo stages. Moreover, EDA and EDAR play an important role in the formation of embryonic placode (Pc). After interfering with EDA and EDAR, the expression of BMP2, BMP4, noggin, β-catenin, TGF-β2, Wnt-10b, and NOTCH1 in fibroblasts and epithelial cells changed significantly. This study provides a theoretical and experimental basis for further studying the molecular regulation mechanism of hair follicle development.

Whole-genome sequencing of Tarim red deer (Cervus elaphus yarkandensis) reveals demographic history and adaptations to an arid-desert environment

Background

The initiation of desert conditions in the Tarim Basin in China since the late Miocene has led to the significant genetic structuring of local organisms. Tarim Red Deer (Cervus elaphus yarkandensis, TRD) have adapted to the harsh environmental conditions in this basin, including high solar radiation and temperature, aridity, and poor nutritional conditions. However, the underlying genetic basis of this adaptation is poorly understood.

Results

We sequenced the whole genomes of 13 TRD individuals, conducted comparative genomic analyses, and estimated demographic fluctuation. The ∂a∂i model estimated that the TRD and Tule elk (Cervus canadensis nannodes) populations diverged approximately 0.98 Mya. Analyses revealed a substantial influence of the Earth’s climate on the effective population size of TRD, associated with glacial advances and retreat, and human activities likely underlie a recent serious decline in population. A marked bottleneck may have profoundly affected the genetic diversity of TRD populations. We detected a set of candidate genes, pathways, and GO categories related to oxidative stress, water reabsorption, immune regulation, energy metabolism, eye protection, heat stress, respiratory system adaptation, prevention of high blood pressure, and DNA damage and repair that may directly or indirectly be involved in the adaptation of TRD to an arid-desert environment.

Conclusions

Our analyses highlight the role of historical global climates in the population dynamics of TRD. In light of ongoing global warming and the increasing incidence of droughts, our study offers insights into the genomic adaptations of animals, especially TRD, to extreme arid-desert environments and provides a valuable resource for future research on conservation design and biological adaptations to environmental change.

Transmembrane collagens-Unexplored mediators of epidermal-dermal communication and tissue homeostasis

Tissue homeostasis is maintained through constant, dynamic and heterogeneous communication between cells and their microenvironment. Proteins that are at the same time active at the intracellular, cell periphery and deeper extracellular levels possess the ability to, on the individual molecular level, influence the cells and their microenvironment in a bidirectional manner. The transmembrane collagens are a family of such proteins, which are of notable interest for tissue development and homeostasis. In skin, expression of all transmembrane collagens has been reported and deficiency of transmembrane collagen XVII manifests with distinct skin phenotypes. Nevertheless, transmembrane collagens in skin remain understudied despite the association of them with epidermal wound healing and dermal fibrotic processes. Here, we present an overview of transmembrane collagens and put a spotlight on them as regulators of epidermal-dermal communication and as potential players in fibrinogenesis.

Divergent genetic mechanism leads to spiny hair in rodents

Spines, or modified hairs, have evolved multiple times in mammals, particularly in rodents. In this study, we investigated the evolution of spines in six rodent families. We first measured and compared the morphology and physical properties of hairs between paired spiny and non-spiny sister lineages. We found two distinct hair morphologies had evolved repeatedly in spiny rodents: hairs with a grooved cross-section and a second near cylindrical form. Compared to the ancestral elliptical-shaped hairs, spiny hairs had higher tension and stiffness, and overall, hairs with similar morphology had similar functional properties. To examine the genetic basis of this convergent evolution, we tested whether a single amino acid change (V370A) in the Ectodysplasin A receptor (Edar) gene is associated with spiny hair, as this substitution causes thicker and straighter hair in East Asian human populations. We found that most mammals have the common amino acid valine at position 370, but two species, the kangaroo rat (non-spiny) and spiny pocket mouse (spiny), have an isoleucine. Importantly, none of the variants we identified are associated with differences in rodent hair morphology. Thus, the specific Edar mutation associated with variation in human hair does not seem to play a role in modifying hairs in wild rodents, suggesting that different mutations in Edar and/or other genes are responsible for variation in the spiny hair phenotypes we observed within rodents.

The resident pathobiont Staphylococcus xylosus in Nfkbiz-deficient skin accelerates spontaneous skin inflammation

IκBζ, which is encoded by the Nfkbiz gene, is a member of the nuclear IκB family of proteins that act as transcriptional regulators via association with NF-κB. Nfkbiz-deficient (Nfkbiz ^-/-) mice develop spontaneous dermatitis; however, the underlying mechanism has yet to be elucidated. In our study, we found higher skin pathology scores and more serum IgE antibodies and trans-epidermal water loss in Nfkbiz ^-/- than in Nfkbiz-sufficient (Nfkbiz ^+/-) mice. There was also greater expansion of IFN-γ-, IL-17A-, and IL-22-secreting CD4⁺ T cells and of IL-17A-secreting γδ⁺ T cells in the skin of Nfkbiz ^-/- mice than in with Nfkbiz ^+/- mice. Pyrosequencing analysis showed decreased diversity of resident bacteria and markedly expanded Staphylococcus (S.) xylosus in the skin of Nfkbiz ^-/- mice. Oral administration of antibiotics including cephalexin and enrofloxacin ameliorated skin inflammation. Topical application of S. xylosus also resulted in the expansion of IL-17A-secreting CD4⁺ T cells along with high levels of pro-inflammatory cytokines and chemokines in the skin of Nfkbiz ^-/- mice. The expansion of commensal S. xylosus may be one cause of skin dysbiosis in Nfkbiz ^-/- mice and suggests that the Nfkbiz gene may play a regulatory role in the microbiota-skin immunity axis.

IL-27 Facilitates Skin Wound Healing through Induction of Epidermal Proliferation and Host Defense

Skin wound repair requires a coordinated program of epithelial cell proliferation and differentiation as well as resistance to invading microbes. However, the factors that trigger epithelial cell proliferation in this inflammatory process are incompletely understood. In this study, we demonstrate that IL-27 is rapidly and transiently produced by CD301b⁺ cells in the skin after injury. The functional role of IL-27 and CD301b⁺ cells is demonstrated by the finding that CD301b-depleted mice exhibit delayed wound closure in vivo, which could be rescued by topical IL-27 treatment. Furthermore, genetic ablation of the IL-27 receptor (Il27Ra^−/−) attenuates wound healing, suggesting an essential role for IL-27 signaling in skin regeneration in vivo. Mechanistically, IL-27 feeds back on keratinocytes to stimulate cell proliferation and re-epithelialization in the skin, whereas IL-27 leads to suppression of keratinocyte terminal differentiation. Finally, we identify that IL-27 potently increases expression of the antiviral oligoadenylate synthetase 2, but does not affect expression of antibacterial human beta defensin 2 or regenerating islet-derived protein 3-alpha. Together, our data suggest a previously unrecognized role for IL-27 in regulating epithelial cell proliferation and antiviral host defense during the normal wound healing response.

Ectodysplasin A in Biological Fluids and Diagnosis of Ectodermal Dysplasia

The tumor necrosis factor (TNF) family ligand ectodysplasin A (EDA) is produced as 2 full-length splice variants, EDA1 and EDA2, that bind to EDA receptor (EDAR) and X-linked EDA receptor (XEDAR/EDA2R), respectively. Inactivating mutations in Eda or Edar cause hypohidrotic ectodermal dysplasia (HED), a condition characterized by malformations of the teeth, hair and glands, with milder deficiencies affecting only the teeth. EDA acts early during the development of ectodermal appendages-as early as the embryonic placode stage-and plays a role in adult appendage function. In this study, the authors measured EDA in serum, saliva and dried blood spots. The authors detected 3- to 4-fold higher levels of circulating EDA in cord blood than in adult sera. A receptor binding-competent form of EDA1 was the main form of EDA but a minor fraction of EDA2 was also found in fetal bovine serum. Sera of EDA-deficient patients contained either background EDA levels or low levels of EDA that could not bind to recombinant EDAR. The serum of a patient with a V262F missense mutation in Eda, which caused a milder form of X-linked HED (XLHED), contained low levels of EDA capable of binding to EDAR. In 2 mildly affected carriers, intermediate levels of EDA were detected, whereas a severely affected carrier had no active EDA in the serum. Small amounts of EDA were also detectable in normal adult saliva. Finally, EDA could be measured in spots of wild-type adult or cord blood dried onto filter paper at levels significantly higher than that measured in EDA-deficient blood. Measurement of EDA levels combined with receptor-binding assays might be of relevance to aid in the diagnosis of total or partial EDA deficiencies.