Number Of Myofibroblasts Research Articles

The transcription factor foxo3 regulates cardiac remodeling after myocardial infarction

Abstract Background Myofibroblast and myeloid cell differentiation following acute myocardial infarction (MI) are important for myocardial fibrosis but also cause adverse remodeling leading to cardiac dysfunction and heart failure. The transcription factor forkhead box O 3 (Foxo3) inhibits hypertrophic cardiac remodeling. We hypothesized that Foxo3, a key regulator of cell differentiation and immunity might inhibit differentiation of fibroblasts and myoloid cells and therefore cardiac fibrosis after MI. Methods MI was induced in Foxo3-/- and wild-type mice by permanent LAD ligation. Cardiac function was determined by transthoracic echocardiography. Cell differentiation was investigated by single nucleus RNA-sequencing (snRNA-seq). Moreover, transdifferentiation assays ex vivo were performed. Results Foxo3-/- mice showed significantly improved survival post- MI (p<0.01) that was in part due to reduced cardiac ruptures (p<0.05). TTE showed reduced LV function, cardiac output, and global strain 4 days post-MI in both groups of animals. However, LV function was significantly attenuated in Foxo3-/- mice 14 d post-MI while diastolic parameters indicated enhanced wall stiffness. snRNA-seq on day 4 post-MI revealed significantly increased numbers of myofibroblasts (p<0.05) transdifferentiating from Progenitor-like state fibroblasts and epicardial derived fibroblasts in Foxo3-/- mice. Myofibroblasts upregulated genes important for extracellular matrix structure and cell migration. Moreover, an upregulation of pro-fibrotic genes was observed in other fibroblast clusters in Foxo3-/- mice and corroborated by significantly elevated collagen type 1 and 3 as well as periostin protein expression. Mechanistically, fibroblasts from Foxo3a-/- mice exhibited enhanced Smad3 dependent myofibroblast marker expression after TGF-ß stimulation. Cell chat analysis indicated enhanced number of interactions and interaction strength of myeloid cells with fibroblasts in Foxo3-/- animals. In line with these observations, differences in cardiac myeloid cell differentiation characterized by reduced center-log ratios of cardiac resident macrophages (Lyve1hiMHCIIlo and Lyve1loMHCIIhi) and increase in monocyte-derived macrophages (Ccr2hi MΦ and Trem2hi MΦ) on day 4 post-MI that was enhanced in Foxo3-/- mice were determined. Differential gene expression patterns on day 4 in pro-inflammatory macrophages (Ccr2hi MΦ) showed upregulation of genes in the interleukin-12 pathway while reparative macrophages (Trem2hi MΦ) revealed an increased expression of genes for extracellular matrix proteins and ECM-collagen interactions in Foxo3-/- mice. Conclusion Our data identify Foxo3 as a master regulator of cardiac remodeling inhibiting myofibroblast and myeloid cell differentiation after acute MI, and suggesting that deficiency of Foxo3 promotes early scar formation but also contributes to adverse matricellular remodeling resulting in impaired cardiac function and enhanced fibrosis.

The Impact of Low-Power Therapeutic Lasers at 904 nm on the Healing Process of Wounds and the Relationships Between Extracellular Matrix Components and Myofibroblasts.

The goal of the study was to further our understanding of the functions that myofibroblasts do, how they interact with the matrix's extracellular elements, and how laser therapy at 904 nm works. Thirty Wistar rats with superficial wounds on the backs were used in this study. The laser therapy device used two energy levels of a 904 nm laser with an output power of 60 mW. The outcomes had been evaluated for one, three, five, seven, and fourteen days following laser therapy. Numerous methods, including as histology, immunohistochemistry, and scanning electron microscopy, have been used to evaluate the tissues.There was a statistically important (P ≤ .05) decrease in the number of inflammatory cells and the degree of edema after laser therapy. On the other hand, the amounts of elastic fiber as well as collagen slightly increased. On the third post-laser treatment day, there was a statistically significant distinction (P < .05) in the number of myofibroblasts with the desmin; smooth muscle alpha-actin phenotype between the laser-treated and control groups.These results suggest that, compared to a higher energy of 5.6 J, laser therapy at a lower energy of 3.6 J may be more effective in stimulating myofibroblast differentiation during the initial phases of wound healing. These findings show how low-power laser therapy promotes wound healing.

A novel senolytic drug for pulmonary fibrosis: BTSA1 targets apoptosis of senescent myofibroblasts by activating BAX.

Idiopathic pulmonary fibrosis is a progressive and age-related disease that results from impaired lung repair following injury. Targeting senescent myofibroblasts with senolytic drugs attenuates pulmonary fibrosis, revealing a detrimental role of these cells in pulmonary fibrosis. The mechanisms underlying the occurrence and persistence of senescent myofibroblasts in fibrotic lung tissue require further clarification. In this study, we demonstrated that senescent myofibroblasts are resistant to apoptosis by upregulating the proapoptotic protein BAX and antiapoptotic protein BCL-2 and BCL-XL, leading to BAX inactivation. We further showed that high levels of inactive BAX-mediated minority mitochondrial outer membrane permeabilization (minority MOMP) promoted DNA damage and myofibroblasts senescence after insult by a sublethal stimulus. Intervention of minority MOMP via the inhibition of caspase activity by quinolyl-valyl-O-methylaspartyl-[2,6-difluorophenoxy]-methyl ketone (QVD-OPH) or BAX knockdown significantly reduced DNA damage and ultimately delayed the progression of senescence. Moreover, the BAX activator BTSA1 selectively promoted the apoptosis of senescent myofibroblasts, as BTSA1-activated BAX converted minority MOMP to complete MOMP while not injuring other cells with low levels of BAX. Furthermore, therapeutic activation of BAX with BTSA1 effectively reduced the number of senescent myofibroblasts in the lung tissue and alleviated both reversible and irreversible pulmonary fibrosis. These findings advance the understanding of apoptosis resistance and cellular senescence mechanisms in senescent myofibroblasts in pulmonary fibrosis and demonstrate a novel senolytic drug for pulmonary fibrosis treatment.

Target NF-κB p65 for preventing posttraumatic joint contracture in rats.

RelA/p65 is as a crucial component of the nuclear factor κB (NF-κB) signaling pathway that has a significant impact on various fibrotic diseases. However, its role in the fibrosis of tissues surrounding the joint after traumatic injury remains unclear. In this study, rats were divided into three groups: non-operated control (NC) group, p65-siRNA treated (siRNA-p65) group, and negative siRNA treated (siRNA-neg) group. Then, 10 μL (10 nmol) of p65-siRNAwas injected into the joint of the siRNA-p65 group. Meanwhile, 10 μL of negative siRNA was administered to the knee joint of the operated siRNA-neg group for comparison. The rats in the NC group did not receive surgery or drug intervention. After 4 weeks of right knee fixation in each group, X-ray measurements revealed significantly reduced degree of knee flexion contracture following p65-siRNA treatment (siRNA-neg: 77.73° ± 2.799°; siRNA-p65: 105.7° ± 2.629°, p < 0.0001). Histopathological examination revealed that the number of dense fibrous connective tissues decreased following p65-siRNA inhibition. Western blot analysis revealed significantly different expression levels of fibrosis-related proteins between the siRNA-p65 and siRNA-neg groups. Immunohistochemical analysis revealed a reduction in the average number of myofibroblasts in the siRNA-p65 group compared with that in the siRNA-neg group. Thus, intra-articular p65-siRNA injection could attenuate fibroblast activation and fibrosis-related protein production, suppress periarticular tissue fibrosis, and prevent joint contracture by downregulating the NF-κB p65 pathway. Statement of clinical significance: Intra-articular injection of p65-siRNA could reduce myofibroblast proliferation and fibrosis-related protein expressionby downregulating the NF-κB p65 pathway, inhibit periarticular tissue fibrosis, and prevent joint adhesion, which representsa potential therapy in the prevention of joint fibrosis following traumatic injury.

P311 KO Mice are Protected from Experimentally Induced Lung Fibrosis

Pulmonary fibrosis (PF) is a fatal chronic interstitial lung disease and one of the most irreversible forms of tissue/organ fibrosis. Idiopathic pulmonary fibrosis is a very progressive disease accompanied by inflammatory damage with a median survival of less than 5 years. Etiology of IPF is still elusive with potential reasons being genetic predisposition and environmental exposures including particulates, radiation, and SARS-CoV-2. Recent studies indicate that about 50% of COVID19 associated acute respiratory distress syndrome survivors develop PF. There are very limited treatment options with no curative therapies available for PF apart from invasive lung transplantation. P311 is an 8 kDa protein previously shown to have a key role in lung regeneration. As P311 overexpression in fibroblasts induced myofibroblast phenotype, we hypothesized that P311 has a role in tissue fibrosis. We induced PF by intra-tracheally instilling bleomycin (BL) in P311 knockout (KO) mice and wild type (WT, C57BL/6) control mice and collected lungs after 2-5 weeks. P311 KO mice showed significantly less fibrosis. After intra-tracheal instillation of BL, the lungs of P311 KO mice (D21) had significantly reduced number of myofibroblasts as indicated by reduced SM α-actin expression and collagen deposition as indicated by Masson trichrome staining compared to their WT counterparts. We further observed reduced levels of TGF-β1-3 and Smad-2 and -3 along with decreased epithelial to mesenchymal transdifferentiation markers in the lungs of bleomycin treated P311 KOs compared to WT controls. Further bronchoalveolar lavage fluid (BALF) was collected (D14) and utilized to determine the pulmonary inflammation by determining the total and different immune cell populations in the BALF and lung samples by FACS analysis. Even though we saw a significant increase in the BALF cellularity, we did not observe significant changes in T-cell, macrophage, and neutrophil numbers between WT and P311KOs. However, lung cell isolates showed significantly increased CD3 and CD4 positive cells indicating increased T-cells and helper T-cells in fibrotic P311KO lungs compared to WT lungs. In conclusion, bleomycin administration resulted in lung fibrosis in WT mice, but P311 KO mice are protected. This study was partially supported by research funding to KB, from American Lung Association, DA-196629-N. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Challenges and opportunities in obesity: the role of adipocytes during tissue fibrosis.

Obesity is a chronic disease that affects the energy balance of the whole body. In addition to increasing fat mass, tissue fibrosis occurred in white adipose tissue in obese condition. Fibrosis is the over-activation of fibroblasts leading to excessive accumulation of extracellular matrix, which could be caused by various factors, including the status of adipocytes. The morphology of adipocytes responds rapidly and dynamically to nutrient fluctuations. Adaptive hypertrophy of normal adipocytes protects peripheral organs from damage from lipotoxicity. However, the biological behavior of hypertrophic adipocytes in chronic obesity is abnormally altered. Adipocytes lead to fibrotic remodeling of the extracellular matrix by inducing unresolved chronic inflammation, persistent hypoxia, and increasing myofibroblast numbers. Moreover, adipocyte-induced fibrosis not only restricts the flexible expansion and contraction of adipose tissue but also initiates the development of various diseases through cellular autonomic and paracrine effects. Regarding anti-fibrotic therapy, dysregulated intracellular signaling and epigenetic changes represent potential candidate targets. Thus, modulation of adipocytes may provide potential therapeutic avenues for reversing pathological fibrosis in adipose tissue and achieving the anti-obesity purpose.

Myofibroblasts reside in the middle dermis of the keloids but do not predict the response to injection therapies: a double-blinded, randomized, controlled trial.

Keloids form as a pathological response to skin wound healing, and their etiopathology is poorly understood. Myofibroblasts, which are cells transformed from normal fibroblasts, are believed to contribute to pathological scar formation in wounds. We carried out a double-blinded randomized controlled trial (RCT) comparing the efficacy of intralesional 5-fluorouracil (5-FU) and triamcinolone (TAC) injections in treating keloids. A total of 43 patients with 50 keloids were treated with either intralesional TAC or 5-FU injections, and their clinical response was evaluated. Biopsies were collected before, during, and after injection therapy from the active border of a keloid. To understand the role of myofibroblasts in keloids, we conducted an immunohistochemical analysis to identify myofibroblasts [α-smooth muscle actin (αSMA)] from the biopsies. We first defined the three histologically distinct regions-superficial, middle, and deep dermis-in each keloid. We then demonstrated that myofibroblasts almost exclusively exist in the middle dermis of the keloids as 80% of the cells in the middle dermis were αSMA positive. However, both the percentage of myofibroblasts as well as the area covered by them was substantially lower in the superficial and deep dermis than in the middle dermis of the keloids. Myofibroblasts do not predict the clinical response to intralesional injection therapies. There is no difference in the myofibroblast numbers in keloids or in the induced change in myofibroblasts between the responders and non-responders after treatment. This study demonstrates that myofibroblasts reside almost exclusively in the middle dermis layer of the keloids, but their numbers do not predict the clinical response to intralesional injection therapies in the RCT.

New insights into the role of the oral leukoplakia microenvironment in malignant transformation.

Oral leukoplakia is the most frequent and potentially malignant lesion of the oral cavity. Although dysplasia grading remains the main factor for risk assessment, challenges persist in determining the exact risk of transformation, and the literature has focused on studying alternative biomarkers. The interaction between dysplastic epithelial cells and the microenvironment starts early, and the communication is mainly mediated by lymphocytes, inflammatory factors, fibroblasts, and the extracellular matrix, leading to dysplastic progression. Leukoplakia-infiltrating leukocytes (LILs) and leukoplakia-associated fibroblasts (LAFs) play crucial roles in the dysplastic microenvironment. The immune response is related to intraepithelial T lymphocyte infiltration, mechanisms of immunosuppression coordinated by regulatory T cells, M2 macrophage polarization, and increased numbers of Langerhans cells; in contrast, fibroblastic and extracellular matrix factors are associated with increased numbers of pro-tumorigenic myofibroblasts, increased expression of metalloproteinases vs. decreased expression of TIMPs, and increased expression of chemokines and other inflammatory mediators. The microenvironment offers insights into the progression of leukoplakia to carcinoma, and understanding the complexity of the oral microenvironment in potentially malignant diseases aids in determining the risk of malignant transformation and proposing new therapeutic alternatives.

Can Shockwave Treatment Elicit a Molecular Response to Enhance Clinical Outcomes in Pressure Ulcers? The SHOck Waves in wouNds Project.

Wound healing requires the coordinated interaction of dermis cells, the proper deposition of extracellular matrix, re-epithelialization, and angiogenesis. Extracorporeal shock wave (ESW) is a promising therapeutic modality for chronic wounds. This study determined the biological mechanisms activated under ESW, facilitating the healing of pressure ulcers (PUs). A group of 10 patients with PUs received two sessions of radial ESW (300 + 100 pulses, 2.5 bars, 0.15 mJ/mm2, 5 Hz). Histomorphological and immunocytochemical assessments were performed on tissue sections obtained from the wound edges before the ESW (M0) and after the first (M1) and second (M2) ESW. The proliferation index of keratinocytes and fibroblasts (Ki-67), the micro-vessels' density (CD31), and the number of myofibroblasts (α-SMA) were evaluated. The involvement of the yes-associated protein (YAP1) in sensing mechanical strain, and whether the nuclear localization of YAP1, was shown. The increased proliferative activity of epidermal cells and skin fibroblasts and the increased number of myofibroblasts, often visible as integrated cell bands, were also demonstrated as an effect of wound exposure to an ESW. The results indicate that the major skin cells, keratinocytes, and fibroblasts are mechanosensitive. They intensify proliferation and extracellular matrix remodeling in response to mechanical stress. A significant improvement in clinical wound parameters was also observed.

Synthesis and preclinical evaluation of a 89Zr-labelled human single chain antibody for non-invasive detection of hepatic myofibroblasts in acute liver injury

Synaptophysin is expressed on fibrogenic hepatic myofibroblasts. C1–3 is a single chain human antibody (scAb) that binds specifically to synaptophysin on hepatic myofibroblasts, providing a targeting vector for novel in vivo imaging agents of chronic liver disease. C1–3 and a negative control scAb, CSBD9, were radiolabelled with zirconium-89 via desferrioxamine chelation to enable non-invasive molecular imaging with positron emission tomography (PET). DFO-scAb conjugates were characterised by gel electrophoresis (SDS-PAGE) and MALDI-TOF spectrometry, and 89Zr-labelled with high radiolabelling efficiency (99%). [89Zr]Zr-DFO-C1–3 exhibited high in vitro stability (> 99%) in mouse and human sera over 3 days at 25 and 37 °C. Activated hepatic myofibroblasts incubated with [89Zr]Zr-DFO-C1–3 displayed significantly higher internalised activity (59.46%, P = 0.001) compared to the [89Zr]Zr-DFO-CSBD9 control, indicating synaptophysin-mediated uptake and high binding specificity of [89Zr]Zr-DFO-C1–3. Mice with CCl4-induced acute liver damage exhibited significantly higher liver uptake of [89Zr]Zr-DFO-C1–3, compared to controls, confirmed by both Cerenkov imaging and ex vivo gamma counting (4.41 ± 0.19%ID/g, P < 0.0001). CCl4-induced liver damage and the number of hepatic myofibroblasts was confirmed by αSMA staining of liver sections. These findings indicate that [89Zr]Zr-DFO-C1–3 has promising utility as a PET imaging agent for non-invasive detection of hepatic myofibroblasts following acute liver injury.

Metformin lotion promotes scarless skin tissue formation through AMPK activation, TGF-β1 inhibition, and reduced myofibroblast numbers.

Scar tissue formation following skin wound healing is a challenging public health problem. Skin regeneration and preventing the formation of scar tissue by currently available commercial products are largely ineffective. This study aimed to test the efficacy of a novel topical metformin lotion (ML) in inhibiting scar tissue formation during skin wound healing in rats and to determine the mechanisms of action involved. A 6% ML was prepared in our laboratory. A skin wound healing model in rats was used. The wounded rats were divided into two groups and treated daily for 10 days as follows: Group 1 received a daily application of 50 mg of control lotion, or 0% ML (totaling 100 mg of lotion per rat), and Group 2 received a daily application of 50 mg of 6% ML (totaling 100 mg of 6% ML per rat). Blood samples from the heart of each rat were analyzed for inflammatory markers, HMGB1 and IL-1β, using ELISA, and immunological and histological analyses were performed on skin tissue sections. ML decreased levels of inflammatory markers HMGB1 and IL-1β in the serum of rats and inhibited the release of HMGB1 from cell nuclei into the skin tissue matrix. Additionally, ML demonstrated anti-fibrotic properties by enhancing AMPK activity, decreasing the expression of TGF-β1, reducing the number of myofibroblasts, decreasing the production of collagen III, and increasing the expression of collagen I. ML promotes the regeneration of high-quality skin during wound healing by reducing scar tissue formation. This effect is mediated through the activation of AMPK, inhibition of TGF-β1, and a decrease in the number of myofibroblasts.

Effects of valproic acid on wound healing of the abdominal wall musculoaponeurotic layer: an experimental study in rats.

valproic acid (VPA), an epigenetic drug, has potential for the treatment of neoplasms. Its effects on the healing of the peritoneal-musculo-aponeurotic plane (PMA) of the abdominal wall are studied. sixty Wistar rats were allocated into two groups: experimental (VPA) and control (0.9% sodium chloride), treated daily, starting three days before the intervention and until euthanasia. Under anesthesia, a median laparotomy was performed and repaired with two synthetic layers. Assessments took place 3, 7 and 14 days after surgery. The integrity of the wounds, the quality of the inflammatory reaction, the intensity of the leukocyte infiltrate, collagen synthesis, the intensity of angiogenesis and the presence of myofibroblasts were studied. there was dehiscence of the PMA plane in 11 of the 30 animals (p=0.001) in the experimental group. There was no difference in the quality and intensity of the inflammatory reaction. Immunohistochemistry revealed, in the experimental group, less collagen I (p3=0.003, p7=0.013 and p14=0.001) and more collagen III (p3=0.003, p7=0.013 and p14= 0.001). Collagen evaluated by Sirus Supra Red F3BA showed, in the experimental group, less collagen at all three times (p<0.001) with less collagen I and collagen III (p<0.001). A lower number of vessels was found on the 3rd day (p<0.001) and on the 7th day (p=0.001) and did not affect the number of myofibroblasts. VPA showed dehiscence of the PMA plane, with less deposition of total collagen and collagen I, less angiogenic activity, without interfering with the number of myofibroblasts.

Injectable Microporous Annealed Crescent-Shaped (MAC) Particle Hydrogel Scaffold for Enhanced Cell Infiltration.

Hydrogels are widely used for tissue engineering applications to support cellular growth, yet the tightly woven structure often restricts cell infiltration and expansion. Consequently, granular hydrogels with microporous architectures have emerged as a new class of biomaterial. Particularly, the development of microporous annealed particle (MAP) hydrogel scaffolds has shown improved stability and integration with host tissue. However, the predominant use of spherically shaped particles limits scaffold porosity, potentially limiting the level of cell infiltration. Here, a novel microporous annealed crescent-shaped particle (MAC) scaffold that is predicted to have improved porosity and pore interconnectivity in silico is presented. With microfluidic fabrication, tunable cavity sizes that optimize interstitial void space features are achieved. In vitro, cells incorporated into MAC scaffolds form extensive 3D multicellular networks. In vivo, the injectable MAC scaffold significantly enhances cell infiltration compared to spherical MAP scaffolds, resulting in increased numbers of myofibroblasts and leukocytes present within the gel without relying on external biomolecular chemoattractants. The results shed light on the critical role of particle shape in cell recruitment, laying the foundation for MAC scaffolds as a next-generation granular hydrogel for diverse tissue engineering applications.

Foxo3a and cardiac myofibroblast transdifferentiation after myocardial infarction

Abstract Background Fibroblast/ myofibroblast differentiation following acute myocardial infarction (MI) is important for myocardial scar formation but also causes adverse remodeling and stiffening of the myocardium leading to cardiac dysfunction and heart failure. Transdifferentiation of myofibroblasts are characterized by periostin, and extracellular matrix protein expression. The transcription factor forkhead box O 3 (FOXO3a) has been recently shown to inhibit hypertrophic cardiac remodeling. Purpose We hypothesized that FOXO3a, a key regulator of cell size, immunity, and cell differentiation, might inhibit transdifferentiation of fibroblasts into myofibroblasts and therefore cardiac fibrosis after MI. Methods Acute MI was induced in Foxo3a-/- mice and wild-type littermates by permanent LAD ligation. Cardiac function was determined by transthoracic echocardiography (TTE) at baseline as well as on days 4 and 14 post-MI. Immune histochemistry was performed with collagen and periostin. Finally, fibroblast differentiation was investigated by single nucleus RNA-sequencing (snRNA-seq). Results Foxo3a-/- mice showed significantly improved survival despite similar infarct size post-MI (p&amp;lt;0.01). The survival advantage was in part due to reduced cardiac ruptures on autopsy. TTE showed reduced LV function, cardiac output, and global strain 4 days post-MI that did not differ between both groups of animals. However, systolic LV function was significantly attenuated in Foxo3a-/- mice 14 days post-MI indicating enhanced wall stiffness. In line with these findings, sn-RNAseq on day 4 post-MI revealed significantly increased numbers of periostin positive myofibroblasts (Myo) (p&amp;lt;0.05) important for stabilizing matrix interactions that transdifferentiated mainly from progenitor-like state fibroblasts (PLS) and homeostatic epicardial derived fibroblasts (HEpiD) in Foxo3a-/- mice. Myo differentially expressed, i.e. upregulated genes important for extracellular matrix structure and organization, cell migration and collagen organization. Moreover, an upregulation of pro-fibrotic genes was observed in other fibroblast clusters such as in HEpiD (i.e., Col1a1, Col1a2, Col3a1), PLS (i.e., fgf10, il1r1), late response fibroblasts (LR-F) (i.e., Col14a1, Rin2) and in activated fibroblasts (F-ACT) (i.e., Gpc6, Slt2) in Foxo3a-/- mice. These changes were corroborated by significantly elevated collagen type 1 and 3 as well as periostin protein expression in Foxo3a-/- mice. Cell chat analysis indicated enhanced number of interactions and interaction strength of myeloid cells with fibroblasts in Foxo3a-/- mice. Conclusion Our data identify Foxo3a as a master regulator of cardiac remodeling attenuating myofibroblast transdifferentiation after acute MI. These findings suggest that deficiency of Foxo3a promotes early scar formation preventing rupture but also contributes to adverse remodeling in later stages resulting in impaired cardiac function and enhanced fibrosis after MI.

Abstract 13045: Myofibroblasts Revert to an Inactive Phenotype During Regression of Heart Failure

Introduction: The therapy of left ventricular mechanical unloading, such as transcatheter aortic valve replacement(TAVR)and left ventricular assist devices(LVAD)has significantly improved prognosis for patients with heart failure. However, the detailed cellular and/or molecular mechanisms of recovery of cardiac function remain unknown. Objective: We aimed to build a cellular atlas of the heart that experienced stress and de-stress process, with a focus on myofibroblasts, specifically its cell fate of differentiation and function. Methods: We conducted single-cell and ATAC sequencing on non-myocardial cells from mouse heart samples of pressure overload-induced heart failure and recovery, using TAC (transverse aortic arch constriction)/deTAC (with suture for the constriction removed 2 weeks after TAC) model to identify the dynamic changes. Lineage tracing technique was also used to gain further insight into cell fate and reciprocal interactions. Macrophage subgroup was cleared using various approaches to investigate the cross-talk between myofibroblast and macrophage. Results: We generated a TAC/deTAC mouse model which can faithfully simulate a reversal process of functioning for the heart that underwent a pressure overload stress. Multi-omics sequencing reveals the genetic changes and transcriptional regulation of cell populations at different stages. Among the different cell types, significant changes in the gene expression pattern were observed in fibroblasts. Aided by myofibroblast lineage tracing, flow cytometry examinations suggested that remaining in a quiescent state rather than showing a decrease in its number appeared as the main fate of myofibroblasts. Surprisingly, however, simultaneous pressure unloading and macrophage clearance resulted in a significant reduction in the number of myofibroblasts. Conclusions: With a reliable TAC/deTAC mouse model, our multi-omics data revealed dynamic changes in cell populations of the heart that underwent pressure overload followed by unloading, our data demonstrated a quiescent state rather than a reduction in number was the major fate for the activated myofibroblasts for which macrophages were involved. These findings provide a theoretical basis for further treatment.

How Porcine Acellular Dermal Matrix Influences the Development of the Breast Capsule 1 Year after Implantation: A Histopathological Analysis.

In prepectoral breast reconstruction (PPBR) the acellular dermal matrix (ADM)'s integration capacity into the tissue is known. The aim of this study was to analyze the effect of the ADM on development and composition of the peri-implant breast capsule in a dynamic setting of breast tissue expansion during two-stage prepectoral breast reconstruction. This is a prospective single-center study in which 50 patients who underwent mastectomy and breast reconstruction with prepectoral tissue expander and Braxon ADM (group A) and submuscular tissue expander (group B) were enrolled. One-year post implantation hematoxylin & eosin (H&E) staining and immunohistochemistry analyses were done on capsule tissue samples. The analysis conducted on H&E-stained samples showed a significant reduction of cellular density and a decrease of the cellular infiltration in capsules of ADM-covered expanders compared with naked expander capsules (P < 0.05). The immunohistochemical analyses showed that group A capsules presented significantly less M1 CD68+ macrophages (P < 0.05), lower alfa-SMA expression levels, and a lower number of myofibroblasts (P < 0.05) compared with group B capsules. Presence of lymphatic vessels was minimally detected in both groups. The ADM presence around the prepectoral tissue expander influences the development of the peri-implant capsule, causing a significant reduction of the number of cells and inflammatory infiltrate, especially M1 macrophages and myofibroblasts. The ADM Braxon is therefore effective in creating a noninflamed capsule around the implant and in dynamic tissue conditions, and such an environment is maintained in time.

Omentin-1 induces mechanically activated fibroblasts lipogenic differentiation through pkm2/yap/pparγ pathway to promote lung fibrosis resolution.

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease characterized by extensive extracellular matrix (ECM) deposition by activated myofibroblasts, which are specialized hyper-contractile cells that promote ECM remodeling and matrix stiffening. New insights on therapeutic strategies aimed at reversing fibrosis by targeting myofibroblast fate are showing promise in promoting fibrosis resolution. Previously, we showed that a novel adipocytokine, omentin-1, attenuated bleomycin (BLM)-induced lung fibrosis by reducing the number of myofibroblasts. Apoptosis, deactivation, and reprogramming of myofibroblasts are important processes in the resolution of fibrosis. Here we report that omentin-1 reverses established lung fibrosis by promoting mechanically activated myofibroblasts dedifferentiation into lipofibroblasts. Omentin-1 promotes myofibroblasts lipogenic differentiation by inhibiting dimerization and nuclear translocation of glycolytic enzymes pyruvate kinase isoform M2 (PKM2) and activation of the downstream Yes-associated protein (YAP) by increasing the cofactor fructose-1,6-bisphosphate (F1, 6BP, FBP). Moreover, omentin-1 activates proliferator-activated receptor gamma (PPARγ) signaling, the master regulator of lipogenesis, and promotes the upregulation of the lipogenic differentiation-related protein perilipin 2 (PLIN2) by suppressing the PKM2-YAP pathway. Ultimately, omentin-1 facilitates myofibroblasts transformation into the lipofibroblast phenotype, with reduced collagen synthesis and enhanced degradation properties, which are crucial mechanisms to clear the ECM deposition in fibrotic tissue, leading to fibrosis resolution. Our results indicate that omentin-1 targets mechanical signal accelerates fibrosis resolution and reverses established lung fibrosis by promoting myofibroblasts lipogenic differentiation, which is closely associated with ECM clearance in fibrotic tissue. These findings suggest that targeting mechanical force to promote myofibroblast lipogenic differentiation is a promising therapeutic strategy against persistent lung fibrosis.

Involvement of Epithelial-Mesenchymal Transition (EMT) in Autoimmune Diseases.

Epithelial-mesenchymal transition (EMT) is a complex reversible biological process characterized by the loss of epithelial features and the acquisition of mesenchymal features. EMT was initially described in developmental processes and was further associated with pathological conditions including metastatic cascade arising in neoplastic progression and organ fibrosis. Fibrosis is delineated by an excessive number of myofibroblasts, resulting in exuberant production of extracellular matrix (ECM) proteins, thereby compromising organ function and ultimately leading to its failure. It is now well acknowledged that a significant number of myofibroblasts result from the conversion of epithelial cells via EMT. Over the past two decades, evidence has accrued linking fibrosis to many chronic autoimmune and inflammatory diseases, including systemic sclerosis (SSc), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), and inflammatory bowel diseases (IBD). In addition, chronic inflammatory states observed in most autoimmune and inflammatory diseases can act as a potent trigger of EMT, leading to the development of a pathological fibrotic state. In the present review, we aim to describe the current state of knowledge regarding the contribution of EMT to the pathophysiological processes of various rheumatic conditions.

Prenatal FGFR2 Signaling via PI3K/AKT Specifies the PDGFRA+ Myofibroblast.

It is well known that FGFR2 (fibroblast growth factor receptor 2) signaling is critical for proper lung development. Recent studies demonstrate that epithelial FGFR2 signaling during the saccular phase of lung development (sacculation) regulates alveolar type 1 (AT1) and AT2 cell differentiation. During sacculation, PDGFRA (platelet-derived growth factor receptor-α)-positive lung fibroblasts exist as three functional subtypes: contractile myofibroblasts, extracellular matrix-producing matrix fibroblasts, and lipofibroblasts. All three subtypes are required during alveolarization to establish a niche that supports AT2 epithelial cell self-renewal and AT1 epithelial cell differentiation. FGFR2 signaling directs myofibroblast differentiation in PDGFRA+ fibroblasts during alveolar reseptation after pneumonectomy. However, it remains unknown if FGFR2 signaling regulates PDGFRA+ myo-, matrix, or lipofibroblast differentiation during sacculation. In this study, FGFR2 signaling was inhibited by temporal expression of a secreted dominant-negative FGFR2b (dnFGFR2) by AT2 cells from embryonic day (E) 16.5 to E18.5. Fibroblast and epithelial differentiation were analyzed at E18.5 and postnatal days 7 and 21. At all time points, the number of myofibroblasts was reduced and the number of lipo-/matrix fibroblasts was increased. AT2 cells are increased and AT1 cells are reduced postnatally, but not at E18.5. Similarly, in organoids made with PDGFRA+ fibroblasts from dnFGFR2 lungs, increased AT2 cells and reduced AT1 cells were observed. In vitro treatment of primary wild-type E16.5 adherent saccular lung fibroblasts with recombinant dnFGFR2b/c resulted in reduced myofibroblast contraction. Treatment with the PI3K/AKT activator 740 Y-P rescued the lack of myofibroblast differentiation caused by dnFGFR2b/2c. Moreover, treatment with the PI3K/AKT activator 740 Y-P rescued myofibroblast differentiation in E18.5 fibroblasts isolated from dnFGFR2 lungs.

Role of myofibroblasts in oral plasma cell granuloma: Immunohistochemical evaluation of α-SMA and ALK in a retrospective study of 30 cases

IntroductionOral plasma cell granuloma (OPCG) is a rare reactive lesion with generally benign yet occasionally aggressive behavior. Myofibroblasts are important in many physiologic, and pathologic conditions. The role of myofibroblasts in the clinical behavior of OPCG was assessed as well as its usefulness in differentiating this lesion from the inflammatory myofibroblastic tumor mimicking plasma cell granuloma. Material and MethodsThis retrospective study included 30 paraffin blocks of OPCG. Immunohistochemical evaluation of alpha-smooth muscle actin (α-SMA) and Anaplastic lymphoma kinase (ALK) antibodies was performed. The mean area of positive expression was calculated and scored semiquantitatively with clinicopathologic correlations. ResultsMost of the cases were clinically non-aggressive. Alveolar bone resorption was observed in nine cases, two of them showed severe resorption and stromal fibrosis. Negative α-SMA was observed in 70% of cases showing a predominance of plasma cells in the stroma. All cases of stromal fibrosis revealed positive α-SMA of a weak percentage. A statistically significant difference was observed between α-SMA expression and the clinicopathologic variables. Negative ALK expression was noted in all cases. DiscussionMyofibroblasts were infrequently found in OPCG. Remarkably, the aggressive behavior in cases with intense fibrosis was related to the existence of myofibroblasts even of non-neoplastic nature and minimal amount. The number of myofibroblasts and their nature assessed via α-SMA and ALK immunohistochemical expression respectively might be valuable in predicting the biological behavior of OPCG and may hold diagnostic significance in challenging OPCG cases that might mimic inflammatory myofibroblastic tumor.