Myofibroblasts: Master of disguise

Variations in ECM Topography, Fiber Alignment, Mechanical Stiffness, and Cellular Composition Between Ventral and Dorsal Ligamentum Flavum Layers: Insights Into Hypertrophy Pathogenesis

Background

Previous studies have suggested that changes in the composition of the extracellular matrix (ECM) play a significant role in the development of ligamentum flavum hypertrophy (LFH) and the histological differences between the ventral and dorsal layers of the hypertrophied ligamentum flavum. Although LFH is associated with increased fibrosis in the dorsal layer, comprehensive research exploring the characteristics of the ECM and its mechanical properties in both regions is limited. Furthermore, the distribution of fibrosis-associated myofibroblasts within LFH remains poorly understood. This study aimed to bridge the existing knowledge gap concerning the intricate relationships between ECM characteristics, mechanical properties, and myofibroblast expression in LFH.

Methods

Histological staining, scanning electron microscopy, and atomic force microscopy were used to analyze the components, alignment, and mechanical properties of the ECM. Immunostaining and western blot analyses were performed to assess the distribution of myofibroblasts in LF tissues.

Results

There were notable differences between the dorsal and ventral layers of the hypertrophic ligamentum flavum. Specifically, the dorsal layer exhibited higher collagen content and disorganized fibrous alignment, resulting in reduced stiffness. Immunohistochemistry analysis revealed a significantly greater presence of α-smooth muscle actin (αSMA)-stained cells, a marker for myofibroblasts, in the dorsal layer.

Conclusions

This study offers comprehensive insights into LFH by elucidating the distinctive ECM characteristics, mechanical properties, and cellular composition disparities between the ventral and dorsal layers. These findings significantly enhance our understanding of the pathogenesis of LFH and may inform future research and therapeutic strategies.

The transcription factor HIF-1α in NKp46+ ILCs limits chronic intestinal inflammation and fibrosis

Innate lymphoid cells (ILCs) are critical for intestinal adaptation to microenvironmental challenges, and the gut mucosa is characterized by low oxygen. Adaptation to low oxygen is mediated by hypoxia-inducible transcription factors (HIFs), and the HIF-1α subunit shapes an ILC phenotype upon acute colitis that contributes to intestinal damage. However, the impact of HIF signaling in NKp46+ ILCs in the context of repetitive mucosal damage and chronic inflammation, as it typically occurs during inflammatory bowel disease, is unknown. In chronic colitis, mice lacking the HIF-1α isoform in NKp46+ ILCs show a decrease in NKp46+ ILC1s but a concomitant rise in neutrophils and Ly6Chigh macrophages. Single-nucleus RNA sequencing suggests enhanced interaction of mesenchymal cells with other cell compartments in the colon of HIF-1α KO mice and a loss of mucus-producing enterocytes and intestinal stem cells. This was, furthermore, associated with increased bone morphogenetic pathway-integrin signaling, expansion of fibroblast subsets, and intestinal fibrosis. In summary, this suggests that HIF-1α-mediated ILC1 activation, although detrimental upon acute colitis, protects against excessive inflammation and fibrosis during chronic intestinal damage.

Inflammatory myofibroblastic tumor in the urinary bladder in a dog

An 8-year-old castrated male Maltese dog was presented with a urinary bladder mass, urolithiasis, and hematuria. A solitary, pedunculated, intraluminal mass on the caudodorsal wall was identified with extensive irregular bladder wall thickening, and the mass was surgically removed. Postoperative histopathology demonstrated a submucosal lesion comprising spindle cells with marked inflammatory cell infiltration, without malignant changes. Immunohistochemical staining revealed vimentin and desmin positivity in the mass. An inflammatory myofibroblastic tumor (IMT) was definitively diagnosed. No recurrence was observed during a 43-month follow-up period. Although IMTs are rare in dogs, they should be considered a differential diagnosis for mass-like urinary bladder lesions accompanying a chronic inflammatory disease process. Key clinical message: Canine IMT should be included in the differential diagnoses of bladder masses, especially when dogs exhibit chronic irritation and inflammation.

Areca nut-induced oral fibrosis - Reassessing the biology of oral submucous fibrosis

BACKGROUND

Oral submucous fibrosis (OSF) is a pathological condition characterized by excessive tissue healing resulting from physical, chemical, or mechanical trauma. Notably, areca nut consumption significantly contributes to the development of oral fibrosis. The current definition of OSF, recognizing its potential for malignant transformation, necessitates a more comprehensive understanding of its pathophysiology and etiology.

HIGHLIGHTS

Areca nut induces fibrotic pathways by upregulating inflammatory cytokines such as TGF-β and expressing additional cytokines. Moreover, it triggers the conversion of fibroblasts to myofibroblasts, characterized by α-SMA and γSMA expression, resulting in accelerated collagen production. Arecoline, a component of areca nut, has been shown to elevate levels of reactive oxygen species, upregulate the expression of various cytokines, and activate specific signaling pathways (MEK, COX2, PI3K), all contributing to fibrosis. Therefore, we propose redefining OSF as "Areca nut-induced oral fibrosis" (AIOF) to align with current epistemology, emphasizing its distinctive association with areca nut consumption. The refined definition enhances our ability to develop targeted interventions, thus contributing to more effective prevention and treatment strategies for oral submucous fibrosis worldwide.

CONCLUSION

Arecoline plays a crucial role as a mediator in fibrosis development, contributing to extracellular matrix accumulation in OSF. The re-evaluation of OSF as AIOF offers a more accurate representation of the condition. This nuanced perspective is essential for distinguishing AIOF from other forms of oral fibrosis and advancing our understanding of the disease's pathophysiology.

Cellular atlas of the human ovary using morphologically guided spatial transcriptomics and single-cell sequencing

The reproductive and endocrine functions of the ovary involve spatially defined interactions among specialized cell populations. Despite the ovary's importance in fertility and endocrine health, functional attributes of ovarian cells are largely uncharacterized. Here, we profiled >18,000 genes in 257 regions from the ovaries of two premenopausal donors to examine the functional units in the ovary. We also generated single-cell RNA sequencing data for 21,198 cells from three additional donors and identified four major cell types and four immune cell subtypes. Custom selection of sampling areas revealed distinct gene activities for oocytes, theca, and granulosa cells. These data contributed panels of oocyte-, theca-, and granulosa-specific genes, thus expanding the knowledge of molecular programs driving follicle development. Serial samples around oocytes and across the cortex and medulla uncovered previously unappreciated variation of hormone and extracellular matrix remodeling activities. This combined spatial and single-cell atlas serves as a resource for future studies of rare cells and pathological states in the ovary.

Dedifferentiated early postnatal lung myofibroblasts redifferentiate in adult disease

Alveolarization ensures sufficient lung surface area for gas exchange, and during bulk alveolarization in mice (postnatal day [P] 4.5-14.5), alpha-smooth muscle actin (SMA)+ myofibroblasts accumulate, secrete elastin, and lay down alveolar septum. Herein, we delineate the dynamics of the lineage of early postnatal SMA+ myofibroblasts during and after bulk alveolarization and in response to lung injury. SMA+ lung myofibroblasts first appear at ∼ P2.5 and proliferate robustly. Lineage tracing shows that, at P14.5 and over the next few days, the vast majority of SMA+ myofibroblasts downregulate smooth muscle cell markers and undergo apoptosis. Of note, ∼8% of these dedifferentiated cells and another ∼1% of SMA+ myofibroblasts persist to adulthood. Single cell RNA sequencing analysis of the persistent SMA- cells and SMA+ myofibroblasts in the adult lung reveals distinct gene expression profiles. For instance, dedifferentiated SMA- cells exhibit higher levels of tissue remodeling genes. Most interestingly, these dedifferentiated early postnatal myofibroblasts re-express SMA upon exposure of the adult lung to hypoxia or the pro-fibrotic drug bleomycin. However, unlike during alveolarization, these cells that re-express SMA do not proliferate with hypoxia. In sum, dedifferentiated early postnatal myofibroblasts are a previously undescribed cell type in the adult lung and redifferentiate in response to injury.

Single-cell sequencing highlights heterogeneity and malignant progression in actinic keratosis and cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most frequent of the keratinocyte-derived malignancies with actinic keratosis (AK) as a precancerous lesion. To comprehensively delineate the underlying mechanisms for the whole progression from normal skin to AK to invasive cSCC, we performed single-cell RNA sequencing (scRNA-seq) to acquire the transcriptomes of 138,982 cells from 13 samples of six patients including AK, squamous cell carcinoma in situ (SCCIS), cSCC, and their matched normal tissues, covering comprehensive clinical courses of cSCC. We identified diverse cell types, including important subtypes with different gene expression profiles and functions in major keratinocytes. In SCCIS, we discovered the malignant subtypes of basal cells with differential proliferative and migration potential. Differentially expressed genes (DEGs) analysis screened out multiple key driver genes including transcription factors along AK to cSCC progression. Immunohistochemistry (IHC)/immunofluorescence (IF) experiments and single-cell ATAC sequencing (scATAC-seq) data verified the expression changes of these genes. The functional experiments confirmed the important roles of these genes in regulating cell proliferation, apoptosis, migration, and invasion in cSCC tumor. Furthermore, we comprehensively described the tumor microenvironment (TME) landscape and potential keratinocyte-TME crosstalk in cSCC providing theoretical basis for immunotherapy. Together, our findings provide a valuable resource for deciphering the progression from AK to cSCC and identifying potential targets for anticancer treatment of cSCC.

Role of PI3K/Akt/mTOR pathway-mediated macrophage autophagy in affecting the phenotype transformation of lung fibroblasts induced by silica dust exposure

OBJECTIVES

The phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway is one of the main signaling pathways related to autophagy. Autophagy plays a key role in the formation of silicosis fibrosis. The phenotypic transformation of lung fibroblasts into myofibroblasts is a hallmark of the transition from the inflammatory phase to the fibrotic phase in silicosis. This study aims to investigate whether the PI3K/Akt/mTOR pathway affects the phenotypic transformation of silicosis-induced lung fibroblasts into myofibroblasts via mediating macrophage autophagy.

METHODS

The human monocytic leukemia cell line THP-1 cells were differentiated into macrophages by treating with 100 ng/mL of phorbol ester for 24 h. Macrophages were exposed to different concentrations (0, 25, 50, 100, 200, 400 μg/mL) and different times (0, 6, 12, 24, 48 h) of SiO2 dust suspension. The survival rate of macrophages was measured by cell counting kit-8 (CCK-8) method. Enzyme linked immunosorbent assay (ELISA) was used to measure the contents of transforming growth factor-β1 (TGF-β1) and tumor necrosis factor-α (TNF-α) in the cell supernatant. The co-culture system of macrophages and HFL-1 cells was established by transwell. A blank control group, a SiO2 group, a LY294002 group, a SC79 group, a LY294002+SiO2 group, and a SC79+SiO2 group were set up in this experiment. Macrophages in the LY294002+SiO2 group were pretreated with LY294002 (PI3K inhibitor) for 18 hours, and macrophages in the SC79+SiO2 group were pretreated with SC79 (Akt activator) for 24 hours, and then exposed to SiO2 (100 μg/mL) dust suspension for 12 hours. The expression of microtubule-associated protein 1 light chain 3 (LC3) protein in macrophages was detected by the immunofluorescence method. The protein expressions of PI3K, Akt, mTOR, Beclin-1, LC3 in macrophages, and collagen III (Col III), α-smooth muscle actin (α-SMA), fibronectin (FN), matrix metalloproteinase-1 (MMP-1), tissue metalloproteinase inhibitor-1 (TIMP-1) in HFL-1 cells were measured by Western blotting.

RESULTS

After the macrophages were exposed to SiO2 dust suspension of different concentrations for 12 h, the survival rates of macrophages were gradually decreased with the increase of SiO2 concentration. Compared with the 0 μg/mL group, the survival rates of macrophages in the 100, 200, and 400 μg/mL groups were significantly decreased, and the concentrations of TGF-β1 and TNF-α in the cell supernatant were obviously increased (all P<0.05). When 100 μg/mL SiO2 dust suspension was applied to macrophages, the survival rates of macrophages were decreased with the prolonged exposure time. Compared with the 0 h group, the survival rates of macrophages were significantly decreased (all P<0.05), the concentrations of TGF-β1 and TNF-α in the cell supernatant were significantly increased, and the protein expression levels of Beclin-1 and LC3II were increased markedly in the 6, 12, 24, and 48 h groups (all P<0.05). Immunofluorescence results demonstrated that after exposure to SiO2 (100 μg/mL) dust for 12 h, LC3 exhibited punctate aggregation and significantly higher fluorescence intensity compared to the blank control group (P<0.05). Compared with the blank control group, the protein expressions of Col III, FN, α-SMA, MMP-1, and TIMP-1 in HFL-1 cells were up-regulated in the SiO2 group (all P<0.05). Compared with the SiO2 group, the protein expressions of PI3K, Akt, and mTOR were down-regulated and the protein expressions of LC3II and Beclin-1 were up-regulated in macrophages (all P<0.05), the contents of TNF-α and TGF-β1 in the cell supernatant were decreased (both P<0.01), and the protein expressions of Col III, FN, α-SMA, MMP-1, and TIMP-1 in HFL-1 cells were down-regulated (all P<0.05) in the LY294002+SiO2 group. Compared with the SiO2 group, the protein expressions of PI3K, Akt, and mTOR were up-regulated and the protein expressions of LC3II and Beclin-1 were down-regulated in macrophages (all P<0.05), the contents of TNF-α and TGF-β1 in the cell supernatant were increased (both P<0.01), and the protein expressions of Col III, FN, α-SMA, MMP-1, and TIMP-1 in HFL-1 cells were up-regulated (all P<0.05) in the SC79+SiO2 group.

CONCLUSIONS

Silica dust exposure inhibits the PI3K/Akt/mTOR pathway, increases autophagy and concentration of inflammatory factors in macrophages, and promotes the phenotype transformation of HFL-1 cells into myofibroblasts. The regulation of the PI3K/Akt/mTOR pathway can affect the autophagy induction and the concentration of inflammatory factors of macrophages by silica dust exposure, and then affect the phenotype transformation of HFL-1 cells into myofibroblasts induced by silica dust exposure.

Identifying fibrogenic cells following salivary gland obstructive injury

Fibrosis results from excess extracellular matrix accumulation, which alters normal tissue architecture and impedes function. In the salivary gland, fibrosis can be induced by irradiation treatment for cancer therapy, Sjögren's Disease, and other causes; however, it is unclear which stromal cells and signals participate in injury responses and disease progression. As hedgehog signaling has been implicated in fibrosis of the salivary gland and other organs, we examined contributions of the hedgehog effector, Gli1, to fibrotic responses in salivary glands. To experimentally induce a fibrotic response in female murine submandibular salivary glands, we performed ductal ligation surgery. We detected a progressive fibrotic response where both extracellular matrix accumulation and actively remodeled collagen significantly increased at 14 days post-ligation. Macrophages, which participate in extracellular matrix remodeling, and Gli1+ and PDGFRα+ stromal cells, which may deposit extracellular matrix, both increased with injury. Using single-cell RNA-sequencing, Gli1 + cells were not found in discrete clusters at embryonic day 16 but were found in clusters expressing the stromal genes Pdgfra and/or Pdgfrb. In adult mice, Gli1+ cells were similarly heterogeneous but more cells co-expressed PDGFRα and PDGFRβ. Using Gli1-CreERT2; ROSA26tdTomato lineage-tracing mice, we found that Gli1-derived cells expand with ductal ligation injury. Although some of the Gli1 lineage-traced tdTomato+ cells expressed vimentin and PDGFRβ following injury, there was no increase in the classic myofibroblast marker, smooth muscle alpha-actin. Additionally, there was little change in extracellular matrix area, remodeled collagen area, PDGFRα, PDGFRβ, endothelial cells, neurons, or macrophages in Gli1 null salivary glands following injury when compared with controls, suggesting that Gli1 signaling and Gli1+ cells have only a minor contribution to mechanical injury-induced fibrotic changes in the salivary gland. We used scRNA-seq to examine cell populations that expand with ligation and/or showed increased expression of matrisome genes. Some Pdgfra + /Pdgfrb + stromal cell subpopulations expanded in response to ligation, with two stromal cell subpopulations showing increased expression of Col1a1 and a greater diversity of matrisome genes, consistent with these cells being fibrogenic. However, only a few cells in these subpopulations expressed Gli1, consistent with a minor contribution of these cells to extracellular matrix production. Defining the signaling pathways driving fibrotic responses in stromal cell sub-types could reveal future therapeutic targets.

A New Approach toward the Management of Patients with Premature Skin Aging Using the Predictor Effect

Our study aimed to develop a comprehensive approach to the management of patients with involutional skin changes, considering the predictors of premature skin aging. The study included two stages, whereby 78 women with no history of aesthetic procedures that could have affected their perceived age were examined. In the first stage, we examined factors associated with premature skin aging. In the second stage, a blind, comparative placebo-controlled study of the effectiveness of intradermal injections for the treatment of involutional skin changes was conducted. Parameters reflecting skin aging were identified. The sum of these parameters could be used to diagnose premature skin aging in patients with no history of aesthetic treatment. For other patients, we developed indicators that can be applied to determine whether there is a risk of premature skin aging. Patients with premature aging have an increased risk of adverse events, such as impaired regeneration and wound healing, postprocedural hematomas, etc. For the correction of involutional skin changes in patients with premature aging, the collagen product (Collost) had the greatest clinical efficiency and the greatest patient satisfaction. A complex product based on HA (Teosyal Redensity 1) had comparable efficiency, with slightly less patient satisfaction. The product based on native HA (Hyon 1.8%) had low efficiency in the group of patients with premature aging and high efficiency in the group of patients with normal aging.

The Extracellular Matrix Vitalizer RATM Increased Skin Elasticity by Modulating Mitochondrial Function in Aged Animal Skin

Oxidative stress-induced cellular senescence and mitochondrial dysfunction result in skin aging by increasing ECM levels-degrading proteins such as MMPs, and decreasing collagen synthesis. MMPs also destroy the basement membrane, which is involved in skin elasticity. The extracellular matrix vitalizer RATM (RA) contains various antioxidants and sodium hyaluronate, which lead to skin rejuvenation. We evaluated whether RA decreases oxidative stress and mitochondrial dysfunction, eventually increasing skin elasticity in aged animals. Oxidative stress was assessed by assaying NADPH oxidase activity, which is involved in ROS generation, and the expression of SOD, which removes ROS. NADPH oxidase activity was increased in aged skin and decreased by RA injection. SOD expression was decreased in aged skin and increased by RA injection. Damage to mitochondrial DNA and mitochondrial fusion markers was increased in aged skin and decreased by RA. The levels of mitochondrial biogenesis markers and fission markers were decreased in aged skin and increased by RA. The levels of NF-κB/AP-1 and MMP1/2/3/9 were increased in aged skin and decreased by RA. The levels of TGF-β, CTGF, and collagen I/III were decreased in aged skin and increased by RA. The expression of laminin and nidogen and basement membrane density were decreased in aged skin and increased by RA. RA increased collagen fiber accumulation and elasticity in aged skin. In conclusion, RA improves skin rejuvenation by decreasing oxidative stress and mitochondrial dysfunction in aged skin.

Identifying Fibrogenic Cells Following Salivary Gland Obstructive Injury

Fibrosis results from excess extracellular matrix accumulation, which alters normal tissue architecture and impedes function. In the salivary gland, fibrosis can be induced by irradiation treatment for cancer therapy, Sjögren's Disease, and other causes; however, it is unclear which stromal cells and signals participate in injury responses and disease progression. As hedgehog signaling has been implicated in fibrosis of the salivary gland and other organs, we examined contributions of the hedgehog effector, Gli1, to fibrotic responses in salivary glands. To experimentally induce a fibrotic response in female murine submandibular salivary glands, we performed ductal ligation surgery. We detected a progressive fibrotic response where both extracellular matrix accumulation and actively remodeled collagen trended upwards at 7 days and significantly increased at 14 days post- ligation. Macrophages, which participate in extracellular matrix remodeling, Gli1 + and PDGFRα + stromal cells, which may deposit extracellular matrix, both increased with injury. Using single-cell RNA-sequencing, we found that a majority of Gli1 + cells at embryonic day 16 also express Pdgfra and/or Pdgfrb. However, in adult mice, only a small subset of Gli1 + cells express PDGFRα and/or PDGFRβ at the protein level. Using lineage-tracing mice, we found that Gli1-derived cells expand with ductal ligation injury. Although some of the Gli1 lineage-traced tdTomato + cells expressed vimentin and PDGFRβ following injury, there was no increase in the classic myofibroblast marker, smooth muscle alpha-actin. Additionally, there was little change in extracellular matrix area, remodeled collagen area, PDGFRα, PDGFRβ, endothelial cells, neurons, or macrophages in Gli1 null salivary glands following injury when compared with controls, suggesting that Gli1 signaling and Gli1 + cells have only a minor contribution to mechanical injury-induced fibrotic changes in the salivary gland. We used scRNA-seq to examine cell populations that expand with ligation and/or showed increased expression of matrisome genes. Pdgfra + /Pdgfrb + stromal cell subpopulations both expanded in response to ligation, showed increased expression and a greater diversity of matrisome genes expressed, consistent with these cells being fibrogenic. Defining the signaling pathways driving fibrotic responses in stromal cell sub-types could reveal future therapeutic targets.

Single-cell transcriptomic analysis of oral masticatory and lining mucosa-derived mesenchymal stromal cells

AIM

To reveal the heterogeneity of ex vivo-cultured human mesenchymal stromal cells derived from either masticatory or lining oral mucosa.

MATERIALS AND METHODS

Cells were retrieved from the lamina propria of the hard palate and alveolar mucosa of three individuals. The analysis of transcriptomic-level differences was accomplished using single-cell RNA sequencing.

RESULTS

Cluster analysis clearly distinguished between cells from the masticatory and lining oral mucosa, and revealed 11 distinct cell sub-populations, annotated as fibroblasts, smooth muscle cells or mesenchymal stem cells. Interestingly, cells presenting a mesenchymal stem cell-like gene expression pattern were predominantly found in masticatory mucosa. Although cells of masticatory mucosa origin were highly enriched for biological processes associated with wound healing, those from the lining oral mucosa were highly enriched for biological processes associated with the regulation of epithelial cells.

CONCLUSIONS

Our previous work had shown that cells from the lining and masticatory oral mucosae are phenotypically heterogeneous. Here, we extend these findings to show that these changes are not the result of differences in averages but rather represent two distinct cell populations, with mesenchymal stem cells more common in masticatory mucosa. These features may contribute to specific physiological functions and have relevance for potential therapeutic interventions.

Fibrotic remodeling and tissue regeneration mechanisms define the therapeutic potential of human muscular progenitors

Fibrosis is an intrinsic biological reaction toward the challenges of tissue injury that is implicated in the wound-healing process. Although it is useful to efficiently mitigate the damage, progression of fibrosis is responsible for the morbidity and mortality occurring in a variety of diseases. Because of lacking effective treatments, there is an emerging need for exploring antifibrotic strategies. Cell therapy based on stem/progenitor cells is regarded as a promising approach for treating fibrotic diseases. Appropriate selection of cellular sources is required for beneficial results. Muscle precursor cells (MPCs) are specialized progenitors harvested from skeletal muscle for conducting muscle regeneration. Whether they are also effective in regulating fibrosis has seldom been explored and merits further investigation. MPCs were successfully harvested from all human samples regardless of demographic backgrounds. The extracellular matrices remodeling was enhanced through the paracrine effects mediated by MPCs. The suppression effects on fibrosis were confirmed in vivo when MPCs were transplanted into the diseased animals with oral submucous fibrosis. The data shown here revealed the potential of MPCs to be employed to simultaneously regulate both processes of fibrosis and tissue regeneration, supporting them as the promising cell candidates for development of the cell therapy for antifibrosis and tissue regeneration.

Molecular mechanisms of TGFβ-mediated EMT of retinal pigment epithelium in subretinal fibrosis of age-related macular degeneration

Age-related macular degeneration (AMD) is one of the leading causes of blindness in the elderly, affecting the macula of the retina and resulting in vision loss. There are two types of AMD, wet and dry, both of which cause visual impairment. Wet AMD is called neovascular AMD (nAMD) and is characterized by the formation of choroidal neovascular vessels (CNVs) in the macula. nAMD can be treated with intravitreal injections of vascular endothelial growth factor (VEGF) inhibitors, which help improve vision. However, approximately half the patients do not achieve satisfactory results. Subretinal fibrosis often develops late in nAMD, leading to irreversible photoreceptor degeneration and contributing to visual loss. Currently, no treatment exists for subretinal fibrosis, and the molecular mechanisms of fibrous tissue formation following neovascular lesions remain unclear. In this review, we describe the clinical features and molecular mechanisms of macular fibrosis secondary to nAMD. Myofibroblasts play an essential role in the development of fibrosis. This review summarizes the latest findings on the clinical features and cellular and molecular mechanisms of the pathogenesis of subretinal fibrosis in nAMD and discusses the potential therapeutic strategies to control subretinal fibrosis in the future.

Epigenetic changes induced by pathogenic Chlamydia spp

Chlamydia trachomatis, C. pneumoniae, and C. psittaci, the three Chlamydia species known to cause human disease, have been collectively linked to several pathologies, including conjunctivitis, trachoma, respiratory disease, acute and chronic urogenital infections and their complications, and psittacosis. In vitro, animal, and human studies also established additional correlations, such as between C. pneumoniae and atherosclerosis and between C. trachomatis and ovarian cancer. As part of their survival and pathogenesis strategies as obligate intracellular bacteria, Chlamydia spp. modulate all three major types of epigenetic changes, which include deoxyribonucleic acid (DNA) methylation, histone post-translational modifications, and microRNA-mediated gene silencing. Some of these epigenetic changes may be implicated in key aspects of pathogenesis, such as the ability of the Chlamydia spp. to induce epithelial-to-mesenchymal transition, interfere with DNA damage repair, suppress cholesterol efflux from infected macrophages, act as a co-factor in human papillomavirus (HPV)-mediated cervical cancer, prevent apoptosis, and preserve the integrity of mitochondrial networks in infected host cells. A better understanding of the individual and collective contribution of epigenetic changes to pathogenesis will enhance our knowledge about the biology of Chlamydia spp. and facilitate the development of novel therapies and biomarkers. Pathogenic Chlamydia spp. contribute to epigenetically-mediated gene expression changes in host cells by multiple mechanisms.

Effect of crude Ganoderma applanatum polysaccharides as a renoprotective agent against carbon tetrachloride-induced early kidney fibrosis in mice

Background and Aim:

Interstitial fibrosis is the final stage of chronic kidney injury, which begins with an inflammatory process. Crude Ganoderma applanatum polysaccharides are known to have anti-inflammatory properties. The potential role of crude G. applanatum polysaccharides in renal fibrosis through pro-inflammatory cytokines needs further investigation. This study aimed to determine the renoprotective effect of crude G. applanatum polysaccharide extract in mice with carbon tetrachloride (CCL₄)-induced early kidney fibrosis.

Materials and Methods:

This study was conducted for 4 weeks using 24 male BALB/c mice selected for their metabolic stability. The mice were randomly divided into six groups, including control (CG), model (MG), silymarin group and crude G. applanatum polysaccharide extract groups comprising doses of 25, 50, and 100 mg/kg body weight. After sacrificing the mice, whole blood was analyzed for urea and creatine levels, and kidney tissue was prepared to assess tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), hyaluronic acid (HA), and laminin levels, both using enzyme-linked immunosorbent assay. Kidney histology was determined using hematoxylin and eosin staining, while the extracellular matrix (ECM) components were stained using Masson’s trichome staining. The α-smooth muscle actin (α-SMA) concentration was determined using immunohistochemistry. These parameters were measured to determine the effectiveness of the crude G. applanatum polysaccharide extract in preventing interstitial fibrosis.

Results:

Administration of crude G. applanatum polysaccharides effectively prevented increases in kidney weight and physiological enzymes, pro-inflammatory cytokines, and ECM production compared with those in the MG, as evidenced by the low levels of urea, creatinine, TNF-α, IL-6, HA, and laminin. Histopathological results also showed that crude G. applanatum polysaccharides prevented the occurrence of inflammatory infiltration, desquamated nuclei, cytoplasm debris, rupture at the brush border, dilatation of the glomeruli space and lumen of the proximal tubule, and necrotic cells compared with the MG. Masson’s trichrome staining revealed lower collagen levels in the interstitial tubules of kidney tissue than those in the MG. Immunohistochemical analysis revealed low α-SMA expression in the crude G. applanatum polysaccharides treatment groups than that in the MG.

Conclusion:

The crude polysaccharide extract of G. applanatum has a protective effect that prevents the progression of kidney fibrosis in mice.

Integrins and Epithelial-Mesenchymal Cooperation in the Tumor Microenvironment of Muscle-Invasive Lethal Cancers

Muscle-invasive lethal carcinomas traverse into and through this specialized biophysical and growth factor enriched microenvironment. We will highlight cancers that originate in organs surrounded by smooth muscle, which presents a barrier to dissemination, including prostate, bladder, esophageal, gastric, and colorectal cancers. We propose that the heterogeneity of cell-cell and cell-ECM adhesion receptors is an important driver of aggressive tumor networks with functional consequences for progression. Phenotype heterogeneity of the tumor provides a biophysical advantage for tumor network invasion through the tensile muscle and survival of the tumor network. We hypothesize that a functional epithelial-mesenchymal cooperation (EMC)exists within the tumor invasive network to facilitate tumor escape from the primary organ, invasion and traversing of muscle, and navigation to metastatic sites. Cooperation between specific epithelial cells within the tumor and stromal (mesenchymal) cells interacting with the tumor is illustrated using the examples of laminin-binding adhesion molecules—especially integrins—and their response to growth and inflammatory factors in the tumor microenvironment. The cooperation between cell-cell (E-cadherin, CDH1) and cell-ECM (α6 integrin, CD49f) expression and growth factor receptors is highlighted within poorly differentiated human tumors associated with aggressive disease. Cancer-associated fibroblasts are examined for their role in the tumor microenvironment in generating and organizing various growth factors. Cellular structural proteins are potential utility markers for future spatial profiling studies. We also examine the special characteristics of the smooth muscle microenvironment and how invasion by a primary tumor can alter this environment and contribute to tumor escape via cooperation between epithelial and stromal cells. This cooperative state allows the heterogenous tumor clusters to be shaped by various growth factors, co-opt or evade immune system response, adapt from hypoxic to normoxic conditions, adjust to varying energy sources, and survive radiation and chemotherapeutic interventions. Understanding the epithelial-mesenchymal cooperation in early tumor invasive networks holds potential for both identifying early biomarkers of the aggressive transition and identification of novel agents to prevent the epithelial-mesenchymal cooperation phenotype. Epithelial-mesenchymal cooperation is likely to unveil new tumor subtypes to aid in selection of appropriate therapeutic strategies.

Pathologic Proteolytic Processing of N-Cadherin as a Marker of Human Fibrotic Disease

Prior research has implicated the involvement of cell adhesion molecule N-cadherin in tissue fibrosis and remodeling. We hypothesize that anomalies in N-cadherin protein processing are involved in pathological fibrosis. Diseased tissues associated with fibrosis of the heart, lung, and liver were probed for the precursor form of N-cadherin, pro-N-cadherin (PNC), by immunohistochemistry and compared to healthy tissues. Myofibroblast cell lines were analyzed for cell surface pro-N-cadherin by flow cytometry and immunofluorescent microscopy. Soluble PNC products were immunoprecipitated from patient plasmas and an enzyme-linked immunoassay was developed for quantification. All fibrotic tissues examined show aberrant PNC localization. Cell surface PNC is expressed in myofibroblast cell lines isolated from cardiomyopathy and idiopathic pulmonary fibrosis but not on myofibroblasts isolated from healthy tissues. PNC is elevated in the plasma of patients with cardiomyopathy (p ≤ 0.0001), idiopathic pulmonary fibrosis (p ≤ 0.05), and nonalcoholic fatty liver disease with cirrhosis (p ≤ 0.05). Finally, we have humanized a murine antibody and demonstrate that it significantly inhibits migration of PNC expressing myofibroblasts. Collectively, the aberrant localization of PNC is observed in all fibrotic tissues examined in our study and our data suggest a role for cell surface PNC in the pathogenesis of fibrosis.

Matters of the heart: Cellular sex differences

Nearly all cardiovascular diseases show sexual dimorphisms in prevalence, presentation, and outcomes. Until recently, most clinical trials were carried out in males, and many animal studies either failed to identify the sex of the animals or combined data obtained from males and females. Cellular sex in the heart is relatively understudied and many studies fail to report the sex of the cells used for in vitro experiments. Moreover, in the small number of studies in which sex is reported, most of those studies use male cells. The observation that cells from males and females are inherently different is becoming increasingly clear - either due to acquired differences from hormones and other factors or due to intrinsic differences in genotype (XX or XY). Because of the likely contribution of cellular sex differences in cardiac health and disease, here, we explore differences in mammalian male and female cells in the heart, including the less-studied non-myocyte cell populations. We discuss how the heart's microenvironment impacts male and female cellular phenotypes and vice versa, including how secretory profiles are dependent on cellular sex, and how hormones contribute to sexually dimorphic phenotypes and cellular functions. Intracellular mechanisms that contribute to sex differences, including gene expression and epigenetic remodeling, are also described. Recent single-cell sequencing studies have revealed unexpected sex differences in the composition of cell types in the heart which we discuss. Finally, future recommendations for considering cellular sex differences in the design of bioengineered in vitro disease models of the heart are provided.

Stationed or Relocating: The Seesawing EMT/MET Determinants from Embryonic Development to Cancer Metastasis

Epithelial and mesenchymal transition mechanisms continue to occur during the cell cycle and throughout human development from the embryo stage to death. In embryo development, epithelial-mesenchymal transition (EMT) can be divided into three essential steps. First, endoderm, mesoderm, and neural crest cells form, then the cells are subdivided, and finally, cardiac valve formation occurs. After the embryonic period, the human body will be subjected to ongoing mechanical stress or injury. The formation of a wound requires EMT to recruit fibroblasts to generate granulation tissues, repair the wound and re-create an intact skin barrier. However, once cells transform into a malignant tumor, the tumor cells acquire the characteristic of immortality. Local cell growth with no growth inhibition creates a solid tumor. If the tumor cannot obtain enough nutrition in situ, the tumor cells will undergo EMT and invade the basal membrane of nearby blood vessels. The tumor cells are transported through the bloodstream to secondary sites and then begin to form colonies and undergo reverse EMT, the so-called "mesenchymal-epithelial transition (MET)." This dynamic change involves cell morphology, environmental conditions, and external stimuli. Therefore, in this manuscript, the similarities and differences between EMT and MET will be dissected from embryonic development to the stage of cancer metastasis.

Electronic Cigarette Exposure Enhances Lung Inflammatory and Fibrotic Responses in COPD Mice

Although a few studies show that the use of electronic nicotine delivery systems (ENDS) may ameliorate objective and subjective outcomes in COPD smokers who switched to electronic cigarettes, it is unclear whether e-cigarette exposure alters lung pathological features and inflammatory response in COPD. Here, we employed βENaC-overexpressing mice bearing COPD-like pulmonary abnormality, and exposed them to ENDS. We found that ENDS exposure aggravated airspace enlargement and mucus production in βENaC-overexpressing mice, which was associated with increased MMP12 and Muc5ac, respectively. ENDS exposure to mice significantly increased the numbers of macrophages, particularly in M2 macrophages in bronchoalveolar lavage (BAL) fluid, despite ENDS did not induce M2 macrophage polarization in a cultured murine macrophage cell line (RAW264.7). There were no changes in neutrophils in BAL fluid by ENDS exposure. Multiple cytokine productions were increased including M-CSF, IL-1rα, IL-10, and TGF-β1, in BAL fluid from mice when exposed to ENDS. The Sirius Red staining and hydroxyproline assay showed ENDS-exposed mice displayed enhanced fibrotic phenotypes compared to control mice. In conclusion, ENDS exposure enhances airspace enlargement, mucus secretion, and fibrogenesis in COPD mice. This is associated with increased MMP12, inflammatory responses, and M2 macrophage phenotype. This study provides pre-clinical data implicating that electronic cigarette exposure is not safe in COPD patients who want to replace traditional cigarettes with ENDS.

The Ameliorative Effects of Arctiin and Arctigenin on the Oxidative Injury of Lung Induced by Silica via TLR-4/NLRP3/TGF-β Signaling Pathway

Silicosis remains one of the most serious diseases worldwide, with no effective drug for its treatment. Our research results have indicated that arctiin and arctigenin could increase the mitochondrial membrane potential, which in turn reduces the production of reactive oxygen species (ROS), blocks the polarization of macrophages, and inhibits the differentiation of myofibroblasts to reduce oxidative stress, inflammation, and fibrosis. Further, our study revealed that arctiin and arctigenin suppressed the activation of NLRP3 inflammasome through the TLR-4/Myd88/NF-κB pathway and the silica-induced secretion of TNF-α, IL-1β, TGF-β, and α-SMA. Besides, the silica-induced increase in the levels of serum ceruloplasmin and HYP was also inhibited. Results of metabolomics indicated that arctiin and arctigenin could regulate the abnormal metabolic pathways associated with the development of silicosis, which involve pantothenate and CoA biosynthesis, cysteine and methionine metabolism, linoleic acid metabolism, and arginine and proline metabolism successively. Furthermore, the analysis of metabolomics, together with network topological analysis in different phases of silicosis, revealed that urine myristic acid, serum 4-hydroxyproline, and L-arginine could be regarded as diagnosis biomarkers in the early phase and formation of pulmonary fibrosis in the latter phases of silicosis. Arctiin and arctigenin could downregulate the increased levels of myristic acid in the early phase and serum 4-hydroxyproline in the latter phase of silicosis. Interestingly, the integration of TLR-4/NLRP3/TGF-β signaling and metabolomics verified the importance of macrophage polarization in the silicosis fibrosis process. To the best of our knowledge, this is the first study reporting that arctiin and arctigenin both can ameliorate silicosis effectively, and the former is a little stronger than its aglycone arctigenin because of its high oral bioavailability, low toxicity, and multimolecular active metabolites as determined by AdmetSAR and molecular docking analysis.

Hypermobile Ehlers-Danlos syndrome: A review and a critical appraisal of published genetic research to date

The Ehlers-Danlos syndromes (EDS) are a collection of rare hereditary connective tissue disorders with heterogeneous phenotypes, usually diagnosed following clinical examination and confirmatory genetic testing. Diagnosis of the commonest subtype, hypermobile Ehlers-Danlos Syndrome (hEDS), relies solely on a clinical diagnosis since its molecular aetiology remains unknown. We performed an up-to-date literature search and selected 11 out of 304 publications according to a set of established criteria. Studies reporting variants affecting collagen proteins were found to be hindered by cohort misclassification and subsequent lack of reproducibility of these genetic findings. The role of the described variants affecting Tenascin-X and LZTS1 is yet to be demonstrated in the majority of hEDS cases, while the functional implication of associated signaling pathways and genes requires further elucidation. The available literature on the genetics of hEDS is scant, dispersed and conflicting due to out-dated nosology terminology. Recent literature has suggested the role of several promising candidate mechanisms which may be linked to the underlying molecular aetiology. Knowledge of the molecular genetic basis of hEDS is expected to increase in the near future through the mainstream use of high-throughput sequencing combined with the updated classification of EDS, and the upcoming Hypermobile Ehlers-Danlos Genetic Evaluation (HEDGE) study.

Diabetic wound healing: The impact of diabetes on myofibroblast activity and its potential therapeutic treatments

Diabetes is a systemic disease in which the body cannot regulate the amount of sugar, namely glucose, in the blood. High glucose toxicity has been implicated in the dysfunction of diabetic wound healing, following insufficient production (Type 1) or inadequate usage (Type 2) of insulin. Chronic non-healing diabetic wounds are one of the major complications of both types of diabetes, which are serious concerns for public health and can impact the life quality of patients significantly. In general, diabetic wounds are characterized by deficient chemokine production, an unusual inflammatory response, lack of angiogenesis and epithelialization, and dysfunction of fibroblasts. Increasing scientific evidence from available experimental studies on animal and cell models strongly associates impaired wound healing in diabetes with dysregulated fibroblast differentiation to myofibroblasts, interrupted myofibroblast activity, and inadequate extracellular matrix production. Myofibroblasts play an important role in tissue repair by producing and organizing extracellular matrix and subsequently promoting wound contraction. Based on these studies, hyperglycaemic conditions can interfere with cytokine signalling pathways (such as growth factor-β pathway) affecting fibroblast differentiation, alter fibroblast apoptosis, dysregulate dermal lipolysis, and enhance hypoxia damage, thus leading to damaged microenvironment for myofibroblast formation, inappropriate extracellular matrix modulation, and weakened wound contraction. In this review, we will focus on the current available studies on the impact of diabetes on fibroblast differentiation and myofibroblast function, as well as potential treatments related to the affected pathways.

Immunohistochemical evaluation of myofibroblasts in odontogenic keratocyst, dentigerous cyst and different clinical variants of ameloblastoma: A comparative study

BACKGROUND

Odontogenic cysts and tumors exhibit varying degrees of aggressiveness in their biological behavior. Odontogenic keratocyst (OKC), dentigerous cyst (DC), ameloblastoma are most common odontogenic cysts and tumors to occur in the oral cavity. Myofibroblasts (MFs) in the connective tissue stroma participate in the matrix degradation process by secreting matrix metalloproteinase 2, transforming growth factor beta1 and may contribute to variation in their biological behavior. Its activity is identified by alpha-smooth muscle actin (α-SMA) marker. With this background, the present study aims to evaluate the frequency of MFs using α-SMA to determine the biological behavior of OKC, DC, and different clinical variants of ameloblastoma.

MATERIALS AND METHODS

A retrospective study was carried out with total of 60 samples which include 10 cases each of OKC, DC, 30 cases of different clinical variants of ameloblastomas and 10 normal mucosa taken as controls. All are stained immunohistochemically using α-SMA and were analyzed for the same. Comparison between more than 2 groups done by one way analysis of variance test with the level of significance of P ≤ 0.0001, i.e., <0.05.

RESULTS

Statistically significant difference in the mean number of MFs observed between certain groups, with higher mean number in solid ameloblastoma (SA) (32.45) followed by OKC (28.79), unicystic ameloblastoma (24.53), desmoplastic ameloblastoma (7.44), and DC (1.72).

CONCLUSION

Higher frequency of MFs noticed in SA, OKC which are key cells for connective tissue remodeling by interacting with epithelial cells and other connective tissue cells to facilitate progression of cysts and tumors thereby contributing to their biological behavior.

Influence of Tumor Microenvironment and Fibroblast Population Plasticity on Melanoma Growth, Therapy Resistance and Immunoescape

Cutaneous melanoma (CM) tissue represents a network constituted by cancer cells and tumor microenvironment (TME). A key feature of CM is the high structural and cellular plasticity of TME, allowing its evolution with disease and adaptation to cancer cell and environmental alterations. In particular, during melanoma development and progression each component of TME by interacting with each other and with cancer cells is subjected to dramatic structural and cellular modifications. These alterations affect extracellular matrix (ECM) remodelling, phenotypic profile of stromal cells, cancer growth and therapeutic response. The stromal fibroblast populations of the TME include normal fibroblasts and melanoma-associated fibroblasts (MAFs) that are highly abundant and flexible cell types interacting with melanoma and stromal cells and differently influencing CM outcomes. The shift from the normal microenvironment to TME and from normal fibroblasts to MAFs deeply sustains CM growth. Hence, in this article we review the features of the normal microenvironment and TME and describe the phenotypic plasticity of normal dermal fibroblasts and MAFs, highlighting their roles in normal skin homeostasis and TME regulation. Moreover, we discuss the influence of MAFs and their secretory profiles on TME remodelling, melanoma progression, targeted therapy resistance and immunosurveillance, highlighting the cellular interactions, the signalling pathways and molecules involved in these processes.

PTEN and α-SMA Expression and Diagnostic Role in Oral Submucous Fibrosis and Oral Squamous Cell Carcinoma with Concomitant Oral Submucous Fibrosis

Objectives

The diagnostic role and correlation between phosphatase and tensin homologue and alpha-smooth muscle actin in oral submucous fibrosis and oral squamous cell carcinoma with concomitant oral submucous fibrosis was analysed by this case control study. The mechanism by which phosphatase and tensin homologue controls myofibroblast expression was also evaluated.

Material and Methods

Overall, 10 normal mucosa, 30 oral submucous fibrosis (OSF) and 30 oral squamous cell carcinoma (OSCC) with OSF were stained immunohistochemically with phosphatase and tensin homologue (PTEN) and alpha-smooth muscle actin (α-SMA). Percentage positivity, pattern of expression was statistically compared using Pearson’s Chi-square and Fischer exact tests. The correlation between markers was analysed using Spearman correlation.

Results

OSF and OSCC affected males predominantly with majority below 40 years and above 40 years of age respectively. Percentage of PTEN positive cells was statistically significant with gender (P = 0.024) and α-SMA distribution of pattern showed a significant correlation with habits (P = 0.018). A significant decrease in nuclear PTEN positivity (P < 0.001) and a gradual increase in α-SMA cytoplasmic expression was noted from NM to OSF and OSCC. A statistically significant weak inverse correlation existed between PTEN and α-SMA.

Conclusions

A reduced phosphatase and tensin homologue expression in oral submucous fibrosis makes it more prone for malignant transformation. An increase in stromal desmoplasia modifies differentiation, invasive and proliferative capacity of tumour cells. As phosphatase and tensin homologue functions through P-Akt pathway, P-Akt with phosphatase and tensin homologue could be a therapeutic target.

Eplerenone Attenuates Fibrosis in the Contralateral Kidney of UUO Rats by Preventing Macrophage-to-Myofibroblast Transition

Severe renal fibrosis often occurs in obstructive kidney disease, not only in the obstructed kidney but also in the contralateral kidney, causing renal dysfunction. Although the mechanisms of injury in obstructed kidney have been studied for years, the pathogenesis of fibrosis in the contralateral kidney remains largely unknown. Here, we examined long-term unilateral ureteral obstruction (UUO) model in male Sprague-Dawley rats and found that macrophage-to-myofibroblast transition (MMT) is contributing to renal fibrosis in the contralateral kidney of UUO rats. Interestingly, this process was attenuated by treatment of eplerenone, a specific blocker of the mineralocorticoid receptor (MR). In-vitro, stimulating MR in primary cultured or cell line macrophages enhances MMT, which were also inhibited by MR blockade. Collectively, these findings provide a plausible mechanism for UUO-induced injury in the contralateral kidney, suggesting the benefit of using MR blockage as a part of treatment to UUO to protect the contralateral kidney thereby preserve renal function.

Characterization of a bovine intestinal myofibroblast cell line and stimulation using phytoglycogen-based nanoparticles bound to inosine monophosphate

The goal of the present study was to characterize a novel bovine intestinal myofibroblast (BT-IMF) cell line isolated from a fetal bovine intestine. This cell type is of importance as intestinal myofibroblasts play a key role in controlling intestinal epithelial cell proliferation, intestinal regulation, wound healing, epithelial cell turnover, and structural support. The present work demonstrates that BT-IMF cells could be successfully cryopreserved and thawed and cultured past 25 passages. Immunocytochemical staining of the BT-IMF cell line was positive for vimentin and smooth muscle actin (α-SMA) and negative for pancytokeratin, suggesting that the cells are myofibroblastic in type. Growth kinetic experiments demonstrate that hydrocortisone negatively impacts BT-IMF growth and non-essential amino acids enhance its proliferation. Inosine monophosphate (IMP) is a dietary nucleotide and is essential for supporting animal health. Stimulation with IMP bound to a novel phytoglycogen-based nanocarrier (IMP-NP) showed enhanced cell proliferation. BT-IMF provides a new tool for studying bovine cells in vitro and may be of particular interest for cultured meat manufacturing in the future.

Cadherin-11 and cardiac fibrosis: A common target for a common pathology

Cardiac fibrosis represents an enormous health concern as it is prevalent in nearly every form of cardiovascular disease, the leading cause of death worldwide. Fibrosis is characterized by the activation of fibroblasts into myofibroblasts, a contractile cell type that secretes significant amounts of extracellular matrix components; however, the onset of this condition is also due to persistent inflammation and the cellular responses to a changing mechanical environment. In this review, we provide an overview of the pro-fibrotic, pro-inflammatory, and biomechanical mechanisms that lead to cardiac fibrosis in cardiovascular diseases. We then discuss cadherin-11, an intercellular adhesion protein present on both myofibroblasts and inflammatory cells, as a potential link for all three of the fibrotic mechanisms. Since experimentally blocking cadherin-11 dimerization prevents fibrotic diseases including cardiac fibrosis, understanding how this protein can be targeted for therapeutic use could lead to better treatments for patients with heart disease.

Sodium alginate-based composites as a collagen substitute for skin bioengineering

The skin is a combination of two different types of tissue-epithelial and connective (mesenchymal). The outer protective layer of the skin, the epidermis, consists of multiple layers of keratinocytes residing on the basement membrane that separates them from the underlying dermis, which consists of a well-vascularized fibrous extracellular matrix seeded mainly by fibroblasts and mesenchymal stromal cells. These skin features suggest that the development of a fibroblast-friendly porous scaffold covered with a flat dense sheath mimicking the basement membrane, and sufficient to support keratinocyte attachment, would be a reasonable approach in the generation of clinically-relevant skin substitutes useful for reconstructive dermatology and burn treatment. Therefore, we developed a procedure to obtain biocompatible composite bilayer scaffolds comprising a spongy dermis-like body (supporting vascularization and appropriate fibroblast and multipotent stromal cell activity) fused with a film-like cover (supporting keratinocyte attachment, growth and differentiation). The sodium alginate (SA), an algae-derived biopolymer, has been used as a base component for these scaffolds while collagen (CL) and fibrinogen (FG) were used as minor additives in variable concentrations. The slow rates of composite SA-based scaffold biodegradation were achieved by using Ba²⁺ as cross-linking cations. By manipulating the SA/CL/FG ratio we managed to obtain sponge scaffolds with highly interconnected porous structures, with an average pore size ranging from 60 to 300 μm, and sufficient tensile strength (3.12-5.26 MPa). The scaffolds biocompatibility with the major human skin cell types was confirmed by seeding the scaffold sponge compartment with primary skin fibroblasts and subcutaneous adipose-derived stromal cells while the film side biocompatibility was tested using primary human keratinocytes. The obtained results have shown that bilayer alginate-based scaffolds have biological and mechanical properties comparable with CL scaffolds but surpass them in cost efficiency and vascularization ability in the subcutaneous implantation model in laboratory mice.

Myofibroblasts and increased angiogenesis contribute to periapical cystic injury containment and repair

Background

Myofibroblasts (MF) and angiogenesis are important factors in the development and expansion of cystic lesions, where these cells secrete growth factors and proteases, stimulating angiogenesis, matrix deposition and cell migration, affecting the growth of these periapicopathies. The present study aimed to evaluate the immunohistochemical expression of CD34 and α-SMA in radicular cysts (RC) and residual radicular cysts (RRC), with the purpose of contributing to a better understanding of the expansion and progression of these periapical lesions.

Material and Methods

The present study os a descriptive, quantitative and comparative analysis of positive CD34 and α-SMA immunohistochemical expressions in 30 RC and 30 RRC specimens. α-SMA expression was evaluated in the fibrous capsule of the lesions, at 100x magnification below the epithelial lining. A total of 10 higher immunostaining fields were selected and subsequently, positive cells were quantified at 400x magnification, averaged per field. Regarding the angiogenic index, immuno-labeled microvessel counts for the anti-CD34 antibody were performed in 10 fields at 200x magnification.

Results

Statistically significant differences regarding α-SMA immunostaining were observed (p = 0.035), as well as a correlation between α-SMA versus CD34 (p = 0.004) in RRC. However, the angiogenic index obtained by immunostaining for CD34 indicated no statistical difference between lesions. Intense inflammatory infiltrates were predominant in RC, while mild and moderate degrees were more commonly observed in RRC (p <0.001). Intense inflammatory infiltrates were also more often noted in larger RRC (p = 0.041). Inflammatory infiltrates showed no significant correlation with α-SMA and CD34 immunostaining.

Conclusions

The results indicate that the significant correlation found between the presence of MF and the angiogenic index are related to the repair process in RRC.

Key words:Myofibroblasts, angiogenesis, inflammatory odontogenic cysts.

Type I Collagen Suspension Induces Neocollagenesis and Myodifferentiation in Fibroblasts In Vitro

The ability of a collagen-based matrix to support cell proliferation, migration, and infiltration has been reported; however, the direct effect of an aqueous collagen suspension on cell cultures has not been studied yet. In this work, the effects of a high-concentration aqueous suspension of a micronized type I equine collagen (EC-I) have been evaluated on a normal mouse fibroblast cell line. Immunofluorescence analysis showed the ability of EC-I to induce a significant increase of type I and III collagen levels, parallel with overexpression of crucial proteins in collagen biosynthesis, maturation, and secretion, prolyl 4-hydroxylase (P4H) and heat shock protein 47 (HSP47), as demonstrated by western blot experiments. The treatment led, also, to an increase of α-smooth muscle actin (α-SMA) expression, evaluated through western blot analysis, and cytoskeletal reorganization, as assessed by phalloidin staining. Moreover, scanning electron microscopy analysis highlighted the appearance of plasma membrane extensions and blebbing of extracellular vesicles. Altogether, these results strongly suggest that an aqueous collagen type I suspension is able to induce fibroblast myodifferentiation. Moreover, our findings also support in vitro models as a useful tool to evaluate the effects of a collagen suspension and understand the molecular signaling pathways possibly involved in the effects observed following collagen treatment in vivo.

Rhein, a novel Histone Deacetylase (HDAC) inhibitor with antifibrotic potency in human myocardial fibrosis

Although fibrosis depicts a reparative mechanism, maladaptation of the heart due to excessive production of extracellular matrix accelerates cardiac dysfunction. The anthraquinone Rhein was examined for its anti-fibrotic potency to mitigate cardiac fibroblast-to-myofibroblast transition (FMT). Primary human ventricular cardiac fibroblasts were subjected to hypoxia and characterized with proteomics, transcriptomics and cell functional techniques. Knowledge based analyses of the omics data revealed a modulation of fibrosis-associated pathways and cell cycle due to Rhein administration during hypoxia, whereas p53 and p21 were identified as upstream regulators involved in the manifestation of cardiac fibroblast phenotypes. Mechanistically, Rhein acts inhibitory on HDAC classes I/II as enzymatic inhibitor. Rhein-mediated cellular effects were linked to the histone deacetylase (HDAC)-dependent protein stabilization of p53 under normoxic but not hypoxic conditions. Functionally, Rhein inhibited collagen contraction, indicating anti-fibrotic property in cardiac remodeling. This was accompanied by increased abundance of SMAD7, but not SMAD2/3, and consistently SMAD-specific E3 ubiquitin ligase SMURF2. In conclusion, this study identifies Rhein as a novel potent direct HDAC inhibitor that may contribute to the treatment of cardiac fibrosis as anti-fibrotic agent. As readily available drug with approved safety, Rhein constitutes a promising potential therapeutic approach in the supplemental and protective intervention of cardiac fibrosis.

Immunoexpression of alpha smooth muscle actin correlates with serum transforming growth factor-β1 levels in oral submucous fibrosis

AIM

The aim of the present study was to correlate the immunoexpression of alpha-smooth muscle actin (α-SMA) for myofibroblasts with the serum levels of transforming growth factor-β1 (TGF-β1) in oral submucous fibrosis (OSMF).

METHODS

A total of 100 cases of histopathologically confirmed OSMF were assessed for α-SMA expression. Clinical data, such as age, sex, mouth opening, and habit history, were obtained for each case. Serum TGF-β1 levels were recorded in 73 patients with the help of enzymelinked immunosorbent assay technique.

RESULTS

The staining index of α-SMA increased concomitantly with higher myofibroblast count in the increasing histopathological grades of OSMF (P ≤ .05). Serum TGF-β1 levels were highest in the intermediate grades of OSMF. Clinical parameters, such as mouth opening, cheek flexibility, and tongue protrusion, showed a direct correlation with increasing clinical grades of OSMF.

CONCLUSIONS

The progressive increase in myofibroblasts from early to advanced stages suggests their potential use as markers for evaluating the severity of OSMF. Additionally, as myofibroblasts are responsible for producing a variety of factors that are involved in the fibrotic processes; they could be the key link in the pathogenesis of OSMF. Interruption of their development, recruitment, or activation could provide a unique therapeutic target for future treatment options in patients with OSMF.

An in vitro study of scarring formation mediated by human Tenon fibroblasts: Effect of Y-27632, a Rho kinase inhibitor

Scar formation is the most common cause for failure of glaucoma filtration surgery because of increased fibroblast proliferation and activation. We have now examined the effect of Y‐27632, a Rho‐associated protein kinase (ROCK) inhibitor, on postsurgical scarring formation in human Tenon fibroblasts (HTFs). Collagen gel contraction assay was used to compare contractility activity of Y‐27632 with several antiglaucoma drugs. Immunofluorescence and western blotting were used to examine expression of scar formation–related factors. We found that Y‐27632 inhibited collagen gel contraction, as well as α‐smooth muscle actin and vimentin expression; these were promoted by treatment with latanoprost, timolol, or transforming growth factor (TGF)–β. To investigate the effect of Y‐27632 in postsurgical scarring, we mimicked TGF‐β secretion by stimulating HTFs with TGF‐β prior to Y‐27632 treatment. HTFs cultured in the presence of TGF‐β significantly increased gel contraction. In contrast, when HTFs were treated with 10μM Y‐27632, contraction was significantly inhibited. Furthermore, Y‐27632 reduced TGF‐β–induced phosphorylation of mitogen‐activated protein kinase signalling. These results suggest that ROCK inhibitors may inhibit fibrosis by inhibiting transdifferentiation of Tenon fibroblasts into myofibroblasts and by inhibiting TGF‐β signalling after surgery through mitogen‐activated protein kinase pathway suppression. These results implicate that ROCK inhibitors may improve outcomes after filtering surgery with a potential antiscarring effect, while latanoprost and timolol may induce fibrosis.

Significance of the study

Scar formation is the primary cause of failure after glaucoma filtration surgery. A ROCK inhibitor, Y‐27632, has been introduced as a novel potential antiglaucoma treatment to reduce intraocular pressure. The aim of our study was to elucidate the effect of Y‐27632 on scarring formation after glaucoma filtration surgery, in direct comparison with other antiglaucoma drugs. Our findings thus suggested that Y‐27632 may inhibit fibrosis and improve outcome after glaucoma filtration surgery through inhibition of transdifferentiation of Tenon fibroblasts into myofibroblasts, and the TGF‐β and MAPK signalling after surgery, while latanoprost and timolol may induce fibrosis.

Platelet-Rich Plasma Prevents In Vitro Transforming Growth Factor-β1-Induced Fibroblast to Myofibroblast Transition: Involvement of Vascular Endothelial Growth Factor (VEGF)-A/VEGF Receptor-1-Mediated Signaling †

The antifibrotic potential of platelet-rich plasma (PRP) is controversial. This study examined the effects of PRP on in vitro transforming growth factor (TGF)-β1-induced differentiation of fibroblasts into myofibroblasts, the main drivers of fibrosis, and the involvement of vascular endothelial growth factor (VEGF)-A in mediating PRP-induced responses. The impact of PRP alone on fibroblast differentiation was also assessed. Myofibroblastic phenotype was evaluated by confocal fluorescence microscopy and western blotting analyses of α-smooth muscle actin (sma) and type-1 collagen expression, vinculin-rich focal adhesion clustering, and stress fiber assembly. Notch-1, connexin 43, and VEGF-A expression were also analyzed by RT-PCR. PRP negatively regulated fibroblast-myofibroblast transition via VEGF-A/VEGF receptor (VEGFR)-1-mediated inhibition of TGF-β1/Smad3 signaling. Indeed TGF-β1/PRP co-treated fibroblasts showed a robust attenuation of the myofibroblastic phenotype concomitant with a decrease of Smad3 expression levels. The VEGFR-1 inhibition by KRN633 or blocking antibodies, or VEGF-A neutralization in these cells prevented the PRP-promoted effects. Moreover PRP abrogated the TGF-β1-induced reduction of VEGF-A and VEGFR-1 cell expression. The role of VEGF-A signaling in counteracting myofibroblast generation was confirmed by cell treatment with soluble VEGF-A. PRP as single treatment did not induce fibroblast myodifferentiation. This study provides new insights into cellular and molecular mechanisms underpinning PRP antifibrotic action.

Immunology Guides Skeletal Muscle Regeneration

Soft tissue trauma of skeletal muscle is one of the most common side effects in surgery. Muscle injuries are not only caused by accident-related injuries but can also be of an iatrogenic nature as they occur during surgical interventions when the anatomical region of interest is exposed. If the extent of trauma surpasses the intrinsic regenerative capacities, signs of fatty degeneration and formation of fibrotic scar tissue can occur, and, consequentially, muscle function deteriorates or is diminished. Despite research efforts to investigate the physiological healing cascade following trauma, our understanding of the early onset of healing and how it potentially determines success or failure is still only fragmentary. This review focuses on the initial physiological pathways following skeletal muscle trauma in comparison to bone and tendon trauma and what conclusions can be drawn from new scientific insights for the development of novel therapeutic strategies. Strategies to support regeneration of muscle tissue after injury are scarce, even though muscle trauma has a high incidence. Based on tissue specific differences, possible clinical treatment options such as local immune-modulatory and cell therapeutic approaches are suggested that aim to support the endogenous regenerative potential of injured muscle tissues.