Pharmacological activation of PPAR-γ: a potential therapy for skin fibrosis

MiR-4769-3p suppresses adipogenesis in systemic sclerosis by negatively regulating the USP18/VDAC2 pathway

Systemic sclerosis (SSc) is an autoimmune disease affecting multiple tissues. The underlying causes and mechanisms of subcutaneous adipose tissue (SAT) loss in SSc remain unclear. Recent studies have highlighted the role of microRNAs in adipogenesis. Our study found that miR-4769-3p was upregulated in SSc patients and its silencing promoted SAT recovery in bleomycin-induced SSc mice, suggesting that miR-4769-3p might affect adipogenesis in SSc. Manipulating miR-4769-3p expression in 3T3-L1 cells revealed that its inhibition enhanced adipogenesis, while its overexpression weakened it. Further investigations showed that miR-4769-3p bound to 3'UTR of ubiquitin-specific protease-18 (USP18), inhibiting its expression, while USP18 interacted with voltage-dependent anion channel-2 (VDAC2), both of which were reduced in SSc. Silencing either USP18 or VDAC2 attenuated adipogenesis. Notably, USP18 inhibited VDAC2 ubiquitination and degradation, whereas miR-4769-3p reversed the VDAC2-induced elevation of adipogenesis, suggesting that miR-4769-3p inhibited adipogenesis by negatively regulating the USP18/VDAC2 pathway, providing a potential therapeutic target for SSc.

A mouse model of progressive lung fibrosis with cutaneous involvement induced by a combination of oropharyngeal and osmotic minipump bleomycin delivery

Systemic sclerosis (SSc) with interstitial lung disease (SSc-ILD) lacks curative pharmacological treatments, thus necessitating effective animal models for candidate drug discovery. Existing bleomycin (BLM)-induced SSc-ILD mouse models feature spatially limited pulmonary fibrosis, spontaneously resolving after 28 days. Here, we present an alternative BLM administration approach in female C57BL/6 mice, combining oropharyngeal aspiration (OA) and subcutaneous mini-pump delivery (pump) of BLM to induce a sustained and more persistent fibrosis, while retaining stable skin fibrosis. A dose-finding study was performed with BLM administered as 10 µg (OA) +80 mg/kg (pump) (10 + 80), 10 + 100, and 15 + 100. Forty-two days after OA, micro-computed tomography (micro-CT) imaging and histomorphometric analyses showed that the 10 + 100 and 15 + 100 treatments induced significant alterations in lung micro-CT-derived readouts, Ashcroft score, and more severe fibrosis grades compared with saline controls. In addition, a marked reduction in hypodermal thickness was observed in the 15 + 100 group. A time-course characterization of the BLM 15 + 100 treatment at days 28, 35, and 42, including longitudinal micro-CT imaging, revealed progressing alterations in lung parameters. Lung histology highlighted a sustained fibrosis accompanied by a reduction in hypodermis thickness throughout the explored time-window, with a time-dependent increase in fibrotic biomarkers detected by immunofluorescence analysis. BLM-induced alterations were partly mitigated by Nintedanib treatment. Our optimized BLM delivery approach leads to extensive and persistent lung fibrotic lesions coupled with cutaneous fibrotic alterations: it thus represents a significant advance compared with current preclinical models of BLM-induced SSc-ILD.NEW & NOTEWORTHY This study introduces an innovative approach to enhance the overall performance of the mouse bleomycin (BLM)-induced model for systemic sclerosis with interstitial lung disease (SSc-ILD). By combining oropharyngeal aspiration and subcutaneous mini-pump delivery of BLM, our improved model leads to sustained lung fibrosis and stable skin fibrosis in female C57BL/6 mice. The optimized 15 + 100 treatment results in extensive and persistent lung fibrotic lesions and thus represents a significant improvement over existing preclinical models of BLM-induced SSc-ILD.

Comprehensive transcriptional analysis of early dorsal skin development in pigs

Porcine skin is similar to human skin in physiology, anatomy and histology and is often used as a model animal for human skin research. There are few studies on the transcriptome aspects of pig skin during the embryonic period. In this study, RNA sequencing was performed on the dorsal skin of Chenghua sows at embryonic day 56 (E56), embryonic day 76 (E76), embryonic day 105 (E105), and 3 days after birth (D3) to explore RNA changes in pig dorsal skin at four ages. A number of skin-related differential genes were identified by intercomparison between RNAs at four time points, and KEGG functional analysis showed that these differential genes were mainly enriched in metabolic and developmental, immune, and disease pathways, and the pathways enriched in GO analysis were highly overlapping. Collagen is an important part of the skin, with type I collagen making up the largest portion. In this study, collagen type I alpha 1 (COL1A1) and collagen type I alpha 2 (COL1A2) were significantly upregulated at four time points. In addition, lncRNA-miRNA-mRNA and miRNA-circRNA coexpression networks were constructed. The data obtained may help to explain age-related changes in transcriptional patterns during skin development and provide further references for understanding human skin development at the molecular level.

Mare stromal endometrial cells differentially modulate inflammation depending on oestrus cycle status: an in vitro study

The modulation of inflammation is pivotal for uterine homeostasis. Here we evaluated the effect of the oestrus cycle on the expression of pro-inflammatory and anti-inflammatory markers in a cellular model of induced fibrosis. Mare endometrial stromal cells isolated from follicular or mid-luteal phase were primed with 10 ng/mL of TGFβ alone or in combination with either IL1β, IL6, or TNFα (10 ng/mL each) or all together for 24 h. Control cells were not primed. Messenger and miRNA expression were analyzed using real-time quantitative PCR (RT-qPCR). Cells in the follicular phase primed with pro-inflammatory cytokines showed higher expression of collagen-related genes (CTGF, COL1A1, COL3A1, and TIMP1) and mesenchymal marker (SLUG, VIM, CDH2, and CDH11) genes; p < 0.05. Cells primed during the mid-luteal overexpressed genes associated with extracellular matrix, processing, and prostaglandin E synthase (MMP2, MMP9, PGR, TIMP2, and PTGES; p < 0.05). There was a notable upregulation of pro-fibrotic miRNAs (miR17, miR21, and miR433) in the follicular phase when the cells were exposed to TGFβ + IL1β, TGFβ + IL6 or TGFβ + IL1β + IL6 + TNFα. Conversely, in cells from the mid-luteal phase, the treatments either did not or diminished the expression of the same miRNAs. On the contrary, the anti-fibrotic miRNAs (miR26a, miR29b, miR29c, miR145, miR378, and mir488) were not upregulated with treatments in the follicular phase. Rather, they were overexpressed in cells from the mid-luteal phase, with the highest regulation observed in TGFβ + IL1β + IL6 + TNFα treatment groups. These miRNAs were also analyzed in the extracellular vesicles secreted by the cells. A similar trend as seen with cellular miRNAs was noted, where anti-fibrotic miRNAs were downregulated in the follicular phase, while notably elevated pro-fibrotic miRNAs were observed in extracellular vesicles originating from the follicular phase. Pro-inflammatory cytokines may amplify the TGFβ signal in the follicular phase resulting in significant upregulation of extracellular matrix-related genes, an imbalance in the metalloproteinases, downregulation of estrogen receptors, and upregulation of pro-fibrotic factors. Conversely, in the luteal phase, there is a protective role mediated primarily through an increase in anti-fibrotic miRNAs, a decrease in SMAD2 phosphorylation, and reduced expression of fibrosis-related genes.

Comprehensive transcriptional analysis of pig facial skin development

Background

Skin development is a complex process that is influenced by many factors. Pig skin is used as an ideal material for xenografts because it is more anatomically and physiologically similar to human skin. It has been shown that the skin development of different pig breeds is different, and some Chinese pig breeds have the characteristics of skin thickness and facial skin folds, but the specific regulatory mechanism of this skin development is not yet clear.

Methods

In this study, the facial skin of Chenghua sows in the four developmental stages of postnatal Day 3 (D3) , Day 90 (D90) , Day 180 (D180), and Year 3 (Y3) were used as experimental materials, and RNA sequencing (RNA-seq) analysis was used to explore the changes in RNA expression in skin development at the four developmental stages, determine the differentially expressed messenger RNAs (mRNAs), long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), and perform functional analysis of related genes by Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses.

Results

A pairwise comparison of the four developmental stages identified several differentially expressed genes (DEGs) and found that the number of differentially expressed RNAs (DE RNAs) increased with increasing developmental time intervals. Elastin (ELN) is an important component of the skin. Its content affects the relaxation of the epidermis and dermal connection, and its expression is continuously downregulated during the four developmental stages. The functions of DEGs at different developmental stages were examined by performing GO and KEGG analyses, and the GO terms and enrichment pathways of mRNAs, lncRNAs, miRNAs, and circRNAs highly overlapped, among which the PPAR signaling pathway, a classical pathway for skin development, was enriched by DEGs of D3 vs. D180, D90 vs. D180 and D180 vs. Y3. In addition, we constructed lncRNA-miRNA-mRNA and circRNA-miRNA interaction networks and found genes that may be associated with skin development, but their interactions need further study.

Conclusions

We identified a number of genes associated with skin development, performed functional analyses on some important DEGs and constructed interaction networks that facilitate further studies of skin development.

Efficacy of probiotic Streptococcus thermophilus in counteracting TGF-β1-induced fibrotic response in normal human dermal fibroblasts

BACKGROUND

Abnormal and deregulated skin wound healing associated with prolonged inflammation may result in dermal fibrosis. Since the current therapeutic strategies revealed unsatisfactory, the investigation of alternative approaches such as those based on the use of specific probiotic strains could provide promising therapeutic options. In this study, we aimed to evaluate whether the lysate from S. thermophilus could antagonize the fibrogenic effects of TGF-β1 in normal human dermal fibroblasts (NHDF).

METHODS

NHDF were exposed to TGF-β1 to establish a fibrotic phenotype. Proliferation rate and cell number were measured using the IncuCyte® Live Cell Imager system and the trypan blue dye exclusion test. Phenoconversion markers (α-SMA and fibronectin) and collagen I levels were assessed by western blot and immunofluorescence. The mRNA levels of TGF-β1 were evaluated by RT-PCR. The Smad2/3 phosphorylation level as well as β-catenin and PPARγ expression, were assessed by western blot. The cell contractility function and migration of NHDF were studied using collagen gel retraction assay, and scratch wound healing assay, respectively. The effects of S. thermophilus lysate, alone or combined with TGF-β1, were evaluated on all of the above-listed parameters and markers associated with TGF-β1-induced fibrotic phenotype.

RESULTS

Exposure to the S. thermophilus lysate significantly reduced the key mediators and events involved in the abnormal activation of myofibroblasts by TGF-β1 within the fibrotic profile. The S. thermophilus treatment significantly reduced cell proliferation, migration, and myo-differentiation. In addition, the treatment with probiotic lysate reduced the α-SMA, fibronectin, collagen-I expression levels, and affected the collagen contraction ability of activated dermal fibroblasts. Moreover, the probiotic targeted the TGF-β1 signaling, reducing Smad2/3 activation, TGF-β1 mRNA level, and β-catenin expression through the upregulation of PPARγ.

CONCLUSION

This is the first report showing that S. thermophilus lysate had a remarkable anti-fibrotic effect in TGF-β1-activated NHDF by inhibiting Smad signaling. Notably, the probiotic was able to reduce β-catenin and increase PPARγ levels. The findings support our point that S. thermophilus may help prevent or treat hypertrophic scarring and keloids.

Cannabinoid Compounds as a Pharmacotherapeutic Option for the Treatment of Non-Cancer Skin Diseases

The endocannabinoid system has been shown to be involved in various skin functions, such as melanogenesis and the maintenance of redox balance in skin cells exposed to UV radiation, as well as barrier functions, sebaceous gland activity, wound healing and the skin's immune response. In addition to the potential use of cannabinoids in the treatment and prevention of skin cancer, cannabinoid compounds and derivatives are of interest as potential systemic and topical applications for the treatment of various inflammatory, fibrotic and pruritic skin conditions. In this context, cannabinoid compounds have been successfully tested as a therapeutic option for the treatment of androgenetic alopecia, atopic and seborrhoeic dermatitis, dermatomyositis, asteatotic and atopic eczema, uraemic pruritis, scalp psoriasis, systemic sclerosis and venous leg ulcers. This review provides an insight into the current literature on cannabinoid compounds as potential medicines for the treatment of skin diseases.

Molecular mechanism of benign biliary stricture inhibition by rosiglitazone-activated peroxisome proliferator-activated receptor gamma

OBJECTIVE

The aim of this study was to investigate whether rosiglitazone-activated peroxisome proliferator-activated receptor gamma can inhibit the occurrence of benign biliary stricture and further elucidate the relevant molecular signaling mechanism.

METHODS

The primary cultured rat biliary fibroblasts following experiments were performed using within the fifth generation cells, which were separated from the bile ducts of Sprague-Dawley rats. The primary cultured rat biliary fibroblasts were co-cultured with 10 ng/mL transforming growth factor-beta 1 for stimulating collagen formation. Competent cells were transfected with siRNA that specifically target Smad3 or connective tissue growth factor to inhibit the expression of the corresponding proteins. The cells were incubated with 10 μmol/L rosiglitazone to activate peroxisome proliferator-activated receptor gamma. The cells were incubated with 10 μmol/L GW9662 in the pretreatment session to inactivate peroxisome proliferator-activated receptor gamma. ELISA was used to determine the levels of connective tissue growth factor and type I collagen in the cell supernatant. Western blotting was used to detect the levels of intracellular p-Smad3/t-Smad3.

RESULTS

Rosiglitazone-activated peroxisome proliferator-activated receptor gamma inhibited the secretion of type I collagen induced by transforming growth factor-beta 1. Peroxisome proliferator-activated receptor gamma inhibitor GW9662 could significantly reverse the rosiglitazone-triggered inhibition of transforming growth factor-beta 1-induced type I collagen secretion by suppressing peroxisome proliferator-activated receptor gamma activation (p<0.01). Furthermore, we also found that the activation of peroxisome proliferator-activated receptor gamma was accompanied by the inhibition of transforming growth factor-beta 1-induced Smad3 phosphorylation (p<0.01), increased connective tissue growth factor expression (p<0.01), and production of type I collagen (p<0.01), all of which effects elicited by rosiglitazone could be reversed by peroxisome proliferator-activated receptor gamma inhibitor GW9662.

CONCLUSION

Peroxisome proliferator-activated receptor gamma activated by rosiglitazone inhibits the transforming growth factor-beta1 -induced phosphorylation of Smad3 and the increased connective tissue growth factor expression as well as inhibits the secretion of type I collagen in biliary fibroblasts.

Topical Use of Cannabis sativa L. Biochemicals

Cannabis sativa L. plant is currently attracting increasing interest in cosmetics and dermatology. In this review, the biologically active compounds of hemp are discussed. Particularly the complex interactions of cannabinoids with the endocannabinoid system of the skin to treat various conditions (such as acne, allergic contact dermatitis, melanoma, and psoriasis) with clinical data. Moreover, the properties of some cannabinoids make them candidates as cosmetic actives for certain skin types. Hemp seed oil and its minor bioactive compounds such as terpenes, flavonoids, carotenoids, and phytosterols are also discussed for their added value in cosmetic formulation.