Inhibitory effect of TGF-β peptide antagonist on the fibrotic phenotype of human hypertrophic scar fibroblasts

Biomechanical Regulatory Factors and Therapeutic Targets in Keloid Fibrosis

Keloids are fibroproliferative skin disorder caused by abnormal healing of injured or irritated skin and are characterized by excessive extracellular matrix (ECM) synthesis and deposition, which results in excessive collagen disorders and calcinosis, increasing the remodeling and stiffness of keloid matrix. The pathogenesis of keloid is very complex, and may include changes in cell function, genetics, inflammation, and other factors. In this review, we aim to discuss the role of biomechanical factors in keloid formation. Mechanical stimulation can lead to excessive proliferation of wound fibroblasts, deposition of ECM, secretion of more pro-fibrosis factors, and continuous increase of keloid matrix stiffness. Matrix mechanics resulting from increased matrix stiffness further activates the fibrotic phenotype of keloid fibroblasts, thus forming a loop that continuously invades the surrounding normal tissue. In this process, mechanical force is one of the initial factors of keloid formation, and matrix mechanics leads to further keloid development. Next, we summarized the mechanotransduction pathways involved in the formation of keloids, such as TGF-β/Smad signaling pathway, integrin signaling pathway, YAP/TAZ signaling pathway, and calcium ion pathway. Finally, some potential biomechanics-based therapeutic concepts and strategies are described in detail. Taken together, these findings underscore the importance of biomechanical factors in the formation and progression of keloids and highlight their regulatory value. These findings may help facilitate the development of pharmacological interventions that can ultimately prevent and reduce keloid formation and progression.

FAK Inhibition Attenuates Corneal Fibroblast Differentiation In Vitro

Corneal fibrosis (or scarring) occurs in response to ocular trauma or infection, and by reducing corneal transparency, it can lead to visual impairment and blindness. Studies highlight important roles for transforming growth factor (TGF)-β1 and -β3 as modulators in corneal wound healing and fibrosis, leading to increased extracellular matrix (ECM) components and expression of α-smooth muscle actin (αSMA), a myofibroblast marker. In this study, human corneal fibroblasts (hCF) were cultured as a monolayer culture (2D) or on poly-transwell membranes to generate corneal stromal constructs (3D) that were treated with TGF-β1, TGF-β3, or TGF-β1 + FAK inhibitor (FAKi). Results show that hCF 3D constructs treated with TGF-β1 or TGF-β3 impart distinct effects on genes involved in wound healing and fibrosis-ITGAV, ITGB1, SRC and ACTA2. Notably, in the 3D construct model, TGF-β1 enhanced αSMA and focal adhesion kinase (FAK) protein expression, whereas TGF-β3 did not. In addition, in both the hCF 2D cell and 3D construct models, we found that TGF-β1 + FAKi attenuated TGF-β1-mediated myofibroblast differentiation, as shown by abrogated αSMA expression. This study concludes that FAK signaling is important for the onset of TGF-β1-mediated myofibroblast differentiation, and FAK inhibition may provide a novel beneficial therapeutic avenue to reduce corneal scarring.

Inhibitory Effect of the LY2109761 on the Development of Human Keloid Fibroblasts

Keloids are scars characterized by abnormal proliferation of fibroblasts and overproduction of extracellular matrix components including collagen. We previously showed that LY2109761, a transforming growth factor- (TGF-) β receptor inhibitor, suppressed the secretion of matrix components and slowed the proliferation of fibroblasts derived from human hypertrophic scar tissue. However, the exact mechanism underlying this effect remains unclear. Here, we replicated the above results in keloid-derived fibroblasts and show that LY2109761 promoted apoptosis, decreased the phosphorylation of Smad2 and Smad3, and suppressed TGF-β1. These results suggest that the development and pathogenesis of keloids are positively regulated by the Smad2/3 signaling pathway and the upregulation of TGF-β1 receptors. LY2109761 and other inhibitors of these processes may therefore serve as therapeutic targets to limit excessive scarring after injury.

Botulinum toxin type A prevents the phenotypic transformation of fibroblasts induced by TGF‑β1 via the PTEN/PI3K/Akt signaling pathway

Hypertrophic scar (HS) is a common type of dermatosis. Botulinum toxin type A (BTXA) can exert an anti-HS effect; however, the regulatory mechanisms underlying this effect remain unclear. Thus, the aim of this study was to examine the effects of BTXA on phosphatase and tensin homolog deleted on chromosome ten (PTEN) expression and the fibroblast phenotypic transformation induced by transforming growth factor (TGF)-β1, which is an important regulatory factor involved in the process of HS. For this purpose, fibroblasts were treated with various concentrations of BTXA and then treated with 10 ng/ml of TGF-β1 with gradient concentrations of BTXA. The proliferation and apoptosis of fibroblasts were measured by cell counting kit-8 assay (CCK-8) and flow cytometry, respectively. PTEN methylation was analyzed by methylation-specific PCR (MSP) and DNA methyltransferase (DNMT) activity was determined using a corresponding kit. RT-qPCR and western blot analysis were performed to detect the transcription and translation levels. The results revealed that BTXA suppressed the proliferation and increased the apoptosis of fibroblasts treated with TGF-β1 in a dose-dependent manner. BTXA in combination with TGF-β1 suppressed the expression of molecules related to the extracellular matrix (ECM), epithelial-mesenchymal transition (EMT) and apoptosis. BTXA reduced the PTEN methylation level and downregulated the expression levels of methylation-associated genes. BTXA also inhibited the phosphorylation of phosphoinositide 3-kinase (PI3K) and Akt. On the whole, the findings of this study indicate that BTXA may inhibit fibroblast phenotypic transformation by regulating PTEN methylation and the phosphorylation of related pathways. The findings of this study can provide a theoretical basis for HS treatment.

Cistanches Herba: An overview of its chemistry, pharmacology, and pharmacokinetics property

ETHNOPHARMACOLOGICAL RELEVANCE

Cistanches Herba is an Orobanchaceae parasitic plant. As a commonly used Traditional Chinese Medicine (TCM), its traditional functions include treating kidney deficiency, impotence, female infertility and senile constipation. Chemical analysis of Cistanches Herba revealed that phenylethanoid glycosides, iridoids, lignans, oligosaccharides, and polysaccharides were the main constituents. Pharmacological studies demonstrated that Cistanches Herba exhibited neuroprotective, immunomodulatory, hormonal balancing, anti-fatigue, anti-inflammatory, hepatoprotection, anti-oxidative, anti-bacterial, anti-viral, and anti-tumor effects, etc. The aim of this review is to provide updated, comprehensive and categorized information on the phytochemistry, pharmacological research and pharmacokinetics studies of the major constituents of Cistanches Herba.

MATERIALS AND METHODS

The literature search was conducted by systematic searching multiple electronic databases including SciFinder, ISI Web of Science, PubMed, Google Scholar and CNKI. Information was also collected from journals, local magazines, books, monographs.

RESULTS

To date, more than 100 compounds have been isolated from this genus, include phenylethanoid glycosides, carbohydrates, lignans, iridoids, etc. The crude extracts and isolated compounds have exhibited a wide range of in vitro and in vivo pharmacologic effects, such as neuroprotective, immunomodulatory, anti-inflammatory, hepatoprotection, anti-oxidative, anti-bacterial, and anti-tumor effects. The phenylethanoid glycosides, echinacoside and acteoside have attracted the most attention for their significantly neuropharmacology effects. Pharmacokinetic studies of echinacoside and acteoside also have also been summarized.

CONCLUSION

Phenylethanoid glycosides have demonstrated wide pharmacological actions and have great clinical value if challenges such as poor bioavailability, fast and extensive metabolism are addressed. Apart from phenylethanoid glycosides, other constituents of Cistanches Herba, their pharmacological activities and underlying mechanisms are also need to be studied further.

Echinacoside Increases Sperm Quantity in Rats by Targeting the Hypothalamic Androgen Receptor

Male infertility is a major health issue with an estimated prevalence of 4.2% of male infertility worldwide. Our early work demonstrated that Cistanche extracts protect against sperm damage in mice and that echinacoside (ECH) is one of the major active components. Here we report an essential role for ECH, a natural product that reverses or protects against oligoasthenospermia in rats. ECH was assayed by HPLC, the quantity and quality of sperm was evaluated and hormone levels were determined by radioimmunosorbent assay. ECH reduced levels of androgen receptor (AR) and key steroidogenic-related genes as determined by Western blot and qPCR analysis. The interaction between ECH and AR were evaluated by indirect ELISA and molecular docking. The results show that ECH combined with hypothalamic AR in the pocket of Met-894 and Val-713 to inhibit transfer of AR from the cytoplasm to nuclei in the hypothalamus. While negative feedback of sex hormone regulation was inhibited, positive feedback was stimulated to increase the secretion of luteinizing hormone and testosterone subsequently enhancing the quantity of sperm. Taken together, these data demonstrate that ECH blocks AR activity in the hypothalamus to increase the quantity of sperm and protect against oligoasthenospermia in rats.

Human adipose-derived stem cells inhibit bioactivity of keloid fibroblasts

Background

A keloid is a fibroproliferative disorder occurring in wounds characterized by an exaggerated response to injury. To date, no effective cure has been identified. As multipotent stem cells, human adipose-derived stem cells (ADSCs) may show the possibility for curing diseases such as fibrosis. This study sought to explore the potential role of human ADSCs in curing keloids.

Methods

After culture in conditioned medium, gene and protein expression of keloid fibroblasts was examined using real-time polymerase chain reaction (RT-PCR) and Western blotting, while analysis of the cell cycle was used to measure the proliferative properties of the cells. Furthermore, ex vivo explant cultures were used to test the effects of ADSC-conditioned medium (ADSC-CM) on CD31⁺ and CD34⁺ expression in keloid tissue.

Results

Our experimental results show that ADSC-CM was able to attenuate extracellular matrix-related gene expression as well as decrease protein expression. Cell proliferation was significantly suppressed in our study. CD31⁺ and CD34⁺ vessels in ex vivo explants were reduced by 55% and 57% in treatment groups compared with control groups.

Conclusions

Human ADSC-CM significantly inhibited keloid fibroblast-related bioactivities.

Murine Precision-Cut Kidney Slices as an ex vivo Model to Evaluate the Role of Transforming Growth Factor-β1 Signaling in the Onset of Renal Fibrosis

Renal fibrosis is characterized by progressive accumulation of extracellular matrix (ECM) proteins, resulting in loss of organ function and eventually requiring renal replacement therapy. Unfortunately, no efficacious treatment options are available to halt renal fibrosis and translational models to test pharmacological agents are not always representative. Here, we evaluated murine precision-cut kidney slices (mPCKS) as a promising ex vivo model of renal fibrosis in which pathophysiology as well as therapeutics can be studied. Unique to this model is the use of rodent as well as human renal tissue, further closing the gap between animal models and clinical trials. Kidneys from C57BL/6 mice were used to prepare mPCKS and slices were incubated up to 96h. Viability, morphology, gene expression of fibrosis markers (Col1a1, Acta2, Serpinh1, Fn1, and Pai-1), inflammatory markers (Il1b, Il6, Cxcl1), and protein expression (collagen type 1, α-smooth muscle actin, HSP47) were determined. Furthermore, to understand the role of the transforming-growth factor β (TGF-β) pathway in mPCKS, slices were incubated with a TGF-β receptor inhibitor (LY2109761) for 48 h. Firstly, viability and morphology revealed an optimal incubation period of 48 h. Secondly, we demonstrated an early inflammatory response in mPCKS, which was accompanied by subsequent spontaneous fibrogenesis. Finally, LY2109761 showed great antifibrotic capacity in mPCKS by decreasing fibrosis markers on mRNA level as well as by reducing HSP47 protein expression. To conclude, we here present an ex vivo model of renal fibrosis, which can be used to further unravel the mechanisms of renal fibrogenesis and to screen antifibrotic therapy efficacy.

Silencing of α-complex protein-2 reverses alcohol- and cytokine-induced fibrogenesis in hepatic stellate cells

BACKGROUND AND AIM

α-complex protein-2 (αCP2) encoded by the poly (rC) binding protein 2(PCBP2) gene is responsible for the accumulation of type I collagen in fibrotic livers. In this study, we silenced the PCBP2 gene using a small interfering RNA (siRNA) to reverse alcohol-and cytokine-induced profibrogenic effects on hepatic stellate cells (HSCs).

METHODS

Primary rat HSCs and the HSC-T6 cell line were used as fibrogenic models to mimic the initiation and perpetuation stages of fibrogenesis, respectively. We previously found that a PCBP2 siRNA, which efficiently silences expression of αCP2, reduces the stability of type I collagen mRNA. We investigated the effects of the PCBP2 siRNA on cell proliferation and migration. Expression of type I collagen in HSCs was analyzed by quantitative real-time PCR and western blotting. In addition, we evaluated the effects of the PCBP2 siRNA on apoptosis and the cell cycle.

RESULTS

PCBP2 siRNA reversed multiple alcohol- and cytokine-induced profibrogenic effects on primary rat HSCs and HSC-T6 cells. The PCBP2 siRNA also reversed alcohol- and cytokine-induced accumulation of type I collagen as well as cell proliferation and migration. Moreover, the combination of LY2109761, a transforming growth factor-β1 inhibitor, and the PCBP2 siRNA exerted a synergistic inhibitive effect on the accumulation of type I collagen in HSCs.

CONCLUSIONS

Silencing of PCBP2 using siRNA could be a potential therapeutic strategy for alcoholic liver fibrosis.

Echinacoside and Cistanche tubulosa (Schenk) R. wight ameliorate bisphenol A-induced testicular and sperm damage in rats through gonad axis regulated steroidogenic enzymes

ETHNOPHARMACOLOGICAL RELEVANCE

Male infertility has been increasing over the last decades and being a pressing health problem nowadays. Cistanche tubulosa (CT) is a traditional Chinese medicine used to boost male sexual function. Echinacoside (ECH) is one of the major compounds exist in CT and might be a potential agent to protect testis and sperm injury.

AIM OF THE STUDY

To investigate the mechanisms behind the possible protective effects of CT and ECH against testicular and sperm toxicity.

MATERIALS AND METHODS

CT was identified by 5.8s gene sequencing. The major compositions (echinacoside and acteoside) of CT were quantified by HPLC method. The adult male Sprague-Dawley rats were exposed to BPA, CT or ECH for 42 consecutive days. The sperm parameters were observed by dark-field microscope; serum hormone levels (FSH, LH and testosterone) were tested by radio immunosorbent; LDH-x activity were evaluated using commercial kits; the expressions of the key steroidogenic enzymes were evaluated by qRT-PCR, heat map, immunofluorescence and western blot.

RESULTS

The CT and ECH treatments against BPA-induced testicular and sperm toxicity showed that CT and ECH have reversed BPA-induced abnormality in sperm characteristics, testicular structure and normalized serum testosterone. This was concomitant with the increased expression of LDH-x as well as the key steroidogenic enzymes including StAR, CYP11A1, 3β-HSD, 17β-HSD and CYP17A1, suggesting that CT and ECH enhanced testosterone biosynthesis.

CONCLUSIONS

CT and ECH attenuated poor sperm quality and testicular toxicity in rats through up-regulation steroidogenesis enzymes and ECH is the active compound of CT as a potential natural reproductive agent.

Involvement of eIF6 in external mechanical stretch-mediated murine dermal fibroblast function via TGF-β1 pathway

External mechanical loading on a wound commonly increases fibrosis. Transforming growth factor-β1 (TGF-β1) has been implicated in fibrosis in various models, including the mechanical force model. However, the underlying mechanism is unclear. Our previous experiments suggested that eukaryotic initiation factor 6 (eIF6) acted as a regulator of TGF-β1 expression, and negatively impact on collagen synthesis. Our current results showed that external mechanical stretching significantly increased COL1A1, TGF-β1 and eIF6 expression as well as dermal fibroblasts proliferation, both in vitro and in vivo. eIF6 –deficient (eIF6^+/−) cells exhibited significantly higher levels of COL1A1, and these levels increased further with external mechanical stretching, suggesting that mechanical stretching plays a synergistic role in promoting COL1A1 expression in eIF6^+/− cells. Inhibition of TGFβR I/II by LY2109761 decreased COL1A1 protein expression in eIF6^+/− dermal fibroblasts in a cell stretching model, and attenuated granulation tissue formation in partial thickness wounds of eIF6^+/− mice. These data suggest that mechanical stretching has a synergistic role in the expression of COL1A1 in eIF6^+/− cells, and is mediated by activation of TGFβRI/II. Taken together, our results indicate that eIF6 may be involved in external mechanical force-mediated murine dermal fibroblast function at least partly through the TGF-β1 pathway.

Growth factor pathways in hypertrophic scars: Molecular pathogenesis and therapeutic implications

Hypertrophic scars represent the most common complication of skin injury and are caused by excessive cutaneous wound healing characterized by hypervascularity and pathological deposition of extracellular matrix (ECM) components. To date, the optimal and specific treatment methods for hypertrophic scars have not been available in the clinic. Current paradigm has established fibroblasts and myofibroblasts as pivotal effector cells in the pathophysiology of wound healing. Their biological properties including origin, proliferation, migration, contraction and ECM regulation have profound impacts on the progression and regression of hypertrophic scars. These complex processes are executed and modulated by a signaling network involving a number of growth factors and cytokines. Of particular importance is transforming growth factor-β, platelet-derived growth factor, connective tissue growth factor, epidermal growth factor, and vascular endothelial growth factor. This review article briefly describes the biological functions of fibroblasts and myofibroblasts during hypertrophic scars, and thereafter examines the up-to-date molecular knowledge on the roles of key growth factor pathways in the pathophysiology of hypertrophic scars. Importantly, the therapeutic implications and future challenges of these molecular discoveries are critically discussed in the hope of advancing therapeutic approaches to limit pathological scar formation.