Unraveling the metastatic niche in breast cancer bone metastasis through single-cell RNA sequencing.

PURPOSE: Breast cancer (BRCA) is characterized by a unique metastatic pattern, often presenting with bone metastasis (BoM), posing significant clinical challenges. Through the study of the immune microenvironment in BRCA BoM offer perspectives for therapeutic interventions targeting this specific metastatic manifestation of BRCA. METHODS: This study employs single-cell RNA sequencing and TCGA data analysis to comprehensively compare primary tumors (PT), lymph node metastasis (LN), and BoM. RESULTS AND CONCLUSIONS: Our investigation identifies a metastatic niche in BoM marked by an increased abundance of cancer-associated fibroblasts (CAFs) and reduced immune cell presence. A distinct subtype (State 1) of BRCA BoM cells associated with adverse prognosis is identified. State 1, displaying heightened stemness traits, may represent an initiation phase for BoM in BRCA. Complex cell communications involving tumor, stromal, and immune cells are revealed. Interactions of FN1, SPP1, and MDK correlate with elevated immune cells in BoM. CD46, MDK, and PTN interactions drive myofibroblast activation and proliferation, contributing to tissue remodeling. Additionally, MDK, PTN, and FN1 interactions influence FAP+ CAF activation, impacting cell adhesion and migration in BoM. These insights deepen our understanding of the metastatic niche in breast cancer BoM.

Assessment of the association of myofibroblasts and structural components of the extracellular matrix with histopathological parameters of actinic cheilitis and lower lip squamous cell carcinoma.

BACKGROUND: To evaluate the presence of myofibroblasts (MFs) in the development of lip carcinogenesis, through the correlation of clinical, histomorphometric and immunohistochemical parameters, in actinic cheilitis (ACs) and lower lip squamous cell carcinomas (LLSCCs). METHODS: Samples of ACs, LLSCCs, and control group (CG) were prepared by tissue microarray (TMA) for immunohistochemical TGF-ß, α-SMA, and Ki-67 and histochemical hematoxylin and eosin, picrosirius red, and verhoeff van gieson reactions. Clinical and microscopic data were associated using the Mann-Whitney, Kruskal-Wallis/Dunn, and Spearman correlation tests (SPSS, p < 0.05). RESULTS: ACs showed higher number of α-SMA+ MFs when compared to CG (p = 0.034), and these cells were associated with the vertical expansion of solar elastosis (SE) itself (p = 0.027). Areas of SE had lower deposits of collagen (p < 0.001), immunostaining for TGF-ß (p < 0.001), and higher density of elastic fibers (p < 0.05) when compared to areas without SE. A positive correlation was observed between high-risk epithelial dysplasia (ED) and the proximity of SE to the dysplastic epithelium (p = 0.027). LLSCCs showed a higher number of α-SMA+ MFs about CG (p = 0.034), as well as a reduction in the deposition of total collagen (p = 0.009) in relation to ACs and CG. There was also a negative correlation between the amount of α-SMA+ cells and the accumulation of total collagen (p = 0.041). Collagen and elastic density loss was higher in larger tumors (p = 0.045) with nodal invasion (p = 0.047). CONCLUSIONS: Our findings show the possible role of MFs, collagen fibers, and elastosis areas in the lip carcinogenesis process.

Potential of Plant-Derived Compounds in Preventing and Reversing Organ Fibrosis and the Underlying Mechanisms.

Increased production of extracellular matrix is a necessary response to tissue damage and stress. In a normal healing process, the increase in extracellular matrix is transient. In some instances; however, the increase in extracellular matrix can persist as fibrosis, leading to deleterious alterations in organ structure, biomechanical properties, and function. Indeed, fibrosis is now appreciated to be an important cause of mortality and morbidity. Extensive research has illustrated that fibrosis can be slowed, arrested or even reversed; however, few drugs have been approved specifically for anti-fibrotic treatment. This is in part due to the complex pathways responsible for fibrogenesis and the undesirable side effects of drugs targeting these pathways. Natural products have been utilized for thousands of years as a major component of traditional medicine and currently account for almost one-third of drugs used clinically worldwide. A variety of plant-derived compounds have been demonstrated to have preventative or even reversal effects on fibrosis. This review will discuss the effects and the underlying mechanisms of some of the major plant-derived compounds that have been identified to impact fibrosis.

Prevalence and anatomopathological characterization of cutaneous squamous cell carcinomas with regional and distant metastases in dogs and cats: 20 cases (1985-2020).

The aim of this study was to assess the prevalence of regional and distant metastases from cutaneous squamous cell carcinomas (SCCs) in dogs (n = 11) and cats (n = 9) in a retrospective case series over 36 years (1985-2020), as well as to characterize its macroscopic aspects (location and size), degree of differentiation (well, moderately and poorly differentiated [WD, MD and PD, respectively]) and the rate of cell proliferation, by counting the AgNORs. Immunohistochemistry (IHC) was used to identify patterns of tumour migration and invasion (islands, ribbons, cords, small aggregates, individual cells [fusiform and amoeboid]) and to evaluate the intensity of desmoplasia and the amount of myofibroblasts. The prevalence of metastatic SCCs was 4.39% (21/478), being 3.8% in dog (12/309) and 5.3% in cat (9/169). Metastases affected lymph nodes in all dogs and 66% (6/9) of cats, and less frequently distant organs. Primary tumours predominantly affected the abdominal skin in dogs and the nasal planum in cats. Among the 20 cases, 52% were MDs, 34% were WDs, and 14% were PDs. Histological lesions suggestive of exposure to chronic solar radiation were present in 57% (8/14). The main patterns of tumour migration and invasion were islands for WD SCCs and individual cells for PD SCCs. MD SCCs had a mix of patterns. In cats, individual spindle cells were restricted to PDs. A marked desmoplastic reaction was more associated with PD SCCs and often with MDs. This study highlights that the prevalence of SCC metastases in dogs and cats is predominantly regional. The IHC was essential in the identification of individual fusiform keratinocytes, whose presence in surgical margins may represent a greater risk of recurrence. Although the presence of myofibroblasts was observed in all infiltrative and metastatic tumours, further studies evaluating these cells may be important to better understand their role in the tumour microenvironment of cutaneous SCCs with metastasis in dogs and cats.

Estudo da imunoexpressão de proteínas envolvidas na transição epitélio-mesênquima em tumores de glândula salivar / Study of the immunoexpression of proteins involved in the epithelial-mesenchymal transition in salivary gland tumors

Os tumores de glândula salivar (TGS) apresentam notável complexidade clínica e biológica, razão para a qual muitos estudos investigam os eventos envolvidos na sua progressão. Uma das dinâmicas envolvidas na invasão tumoral de diversos tipos de carcinomas é a transição epitélio-mesênquima (TEM). Neste processo, as células epiteliais sofrem transição para um estado mesenquimal móvel, favorecendo a invasão e metástase. Sendo assim, esta pesquisa analisou a expressão imuno-histoquímica de E-caderina, Twist1, Snail1, α-SMA, metaloproteinases de matriz 9 (MMP-9) e Vimentina (VM) em 90 casos de TGS, correlacionando-os entre si e com parâmetros clinicopatológicos. Foram selecionados 20 casos de Adenoma pleomórfico (AP), 20 casos de Carcinoma mucoepidermoide (CME), 20 casos de Carcinoma adenoide cístico (CAC), 10 casos de Adenocarcinoma polimorfo (ACP), 10 casos de Carcinoma epitelial-mioepitelial (CEME) e 10 casos de Carcinoma ex-adenoma pleomórfico (CexAP). A análise de E-caderina, Twist1, Snail1 foi realizada em parênquima tumoral sendo observado o percentual de células positivas (PP), com escores variando de 0 a 4, e a intensidade de expressão (IE), cujos escores variaram de 0 a 3. A avaliação de MMP-9 foi realizada em parênquima e estroma tumoral, também avaliando-se a PP e a IE, ambos baseados em escores que variaram de 0 a 3. A marcação para α-SMA e VM foi analisada em região de estroma tumoral. Células positivas para α-SMA foram contabilizadas em 10 campos, obtendo-se, então a média. A VM foi avaliada de forma qualitativa, utilizando-se 4 escores de acordo com a IE e se a marcação é difusa ou focal. Os dados obtidos foram analisados no software Statistical Package for Social Science, GraphPad Prism e STATA. O nível de significância de 5% foi adotado para os testes estatísticos. Foi verificada menor imunomarcação de E-caderina nos APs em relação às neoplasias malignas de glândula salivar (NMGS). Observou-se baixa imunoexpressão de Twist1 e Snail1 em APs. Em relação a expressão nuclear do Twist1, constatou-se maior expressão nas neoplasias malignas quando comparadas aos APs. Ainda, Twist1 em núcleo foi correlacionado à expressão citoplasmática de E-caderina nas NMGS. No que concerne aos parâmetros clinicopatológicos, esta proteína se relacionou estatisticamente com maiores chances de óbito. Foi evidenciada baixa imunoexpressão de Snail1 entre as NMGS. No entanto, na análise dos CACs, foi verificada maior expressão nuclear na variante sólida em relação às demais. A expressão de MMP-9 em parênquima demonstrou correlação positiva com Twist1 citoplasmático e Snail1nuclear nas NMGS. A MMP-9 também apresentou correlação positiva na comparação da sua imunoexpressão em região de parênquima e de estroma. A VM se apresentou como um biomarcador a ser considerado na avaliação clínica dos pacientes, já que esta apresentou relação significativa com tamanho do tumor (T3-T4) e maior frequência de óbito. Ademais, a alta expressão desta proteína se apresentou como um fator preditivo independente para piores taxas de sobrevida global (SG). A avaliação dos demais fatores clinicopatológicos apresentou estágios clínicos avançados como indicador de valor prognóstico independente para menores taxas de SG, enquanto que para a sobrevida livre da doença, estes foram a localização em glândula salivar menor e presença de metástase à distância. Os resultados deste estudo sugerem que o processo de TEM pode estar relacionado ao estágio de diferenciação celular em APs e à progressão tumoral nas NMGS. Ressalta-se, também, maior participação de Twist1 e MMP-9 no cenário da TEM em tumores malignos de glândula salivar, além da possibilidade de utilização da VM como indicador de valor prognóstico (AU).

Salivary gland tumors (SGTs) present remarkable clinical and biological complexity; therefore, many studies investigate the events involved in their progression. One of the dynamics involved in the tumor invasion of different types of carcinomas is the epithelial-mesenchymal transition (EMT). In this process, epithelial cells undergo a transition to a mobile mesenchymal state, favoring invasion and metastasis. Therefore, this research analyzed the immunohistochemical expression of E-cadherin, Twist1, Snail1, α-SMA, vimentin (VM) and matrix metalloproteinase 9 (MMP-9) in 90 SGTs cases; correlations among the biomarkers, as well as between the biomarkers and clinicopathological parameters were made. We selected 20 cases of pleomorphic adenoma (PA), 20 cases of mucoepidermoid carcinoma (MEC), 20 cases of adenoid cystic carcinoma (ACC), 10 cases of polymorphous adenocarcinoma (PAC), 10 cases of epithelial-myoepithelial carcinoma (EMC) and 10 cases of carcinoma ex-pleomorphic adenoma (CXPA). E-cadherin, Twist1, and Snail1 were analyzed in tumor parenchyma, observing the percentage of positive cells (PP) using scores ranging from 0 to 4, and the expression intensity (EI), whose scores were ranged from 0 to 3. The evaluation of MMP-9 was performed in tumor parenchyma and stroma, also evaluating PP and IE, both based on scores that ranged from 0 to 3. The labeling for α-SMA and VM was analyzed in stromal cells. Positive cells for α-SMA were counted in 10 fields and the mean was calculated. VM was evaluated qualitatively, using 4 scores according to EI and whether the labeling was diffuse or focal. Obtained data were analyzed using Statistical Package for Social Science, GraphPad Prism, and STATA software. The significance level of 5% was adopted for the statistical tests. Patients were mostly female, with a mean age of 49.8 years; the major salivary glands were the most affected anatomical site, mainly the parotid gland. A lower E-cadherin immunostaining was verified in PAs in comparison to malignant neoplasms of salivary glands (MNSGs). Low immunoexpression of Twist1 and Snail1 was observed in PAs. Regarding the nuclear expression of Twist1, it was found greater expression in malignant neoplasms than in PAs. Furthermore, Twist1 in the nucleus was correlated with cytoplasmic expression of E-cadherin in MNSGs. Regarding clinicopathological parameters, this protein was statistically related to higher chances of death. Low immunoexpression of Snail1 was evidenced among the MNSGs. However, in the analysis of CACs, greater nuclear expression was observed in the solid variant compared to the others. Expression of MMP-9 in parenchyma showed a positive correlation with cytoplasmic Twist1 and Snail1nuclear in MNSGs. MMP-9 also showed a positive correlation when comparing its immunoexpression in the parenchyma and the stroma. VM was presented as a biomarker to be considered in the clinical evaluation of patients since it showed a significant correlation between greater tumor size and a higher frequency of death. Furthermore, the high expression of this protein appeared as an independent predictive factor for worse overall survival (OS) rates. The evaluation of the rest of the clinicopathological factors showed advanced clinical stages as an indicator of independent prognostic value for lower rates of OS. For disease-free survival, these indicators were the location in the minor salivary gland and the presence of distant metastasis. Our results suggest that the EMT may be related to myoepithelial differentiation in PAs and tumor progression in MNSGs. Also, Twist1 and MMP-9 appear to play a greater role in the scenario of EMT in MNSGs; finally, VM might be used as a prognostic value indicator (AU).

Primary non-metastatic omental myofibrosarcoma in a horse / Miofibrossarcoma omental primário não metastático em um cavalo

Myofibrosarcoma in horses is a rare malignant tumor composed predominantly by myofibroblasts. A 15-year-old horse was referred to the Veterinary Hospital of the Federal University of Parana for evaluation of colic signs. Initial physical examination showed icteric mucous membrane and laboratory analysis found anemia, increased serum activity of ALT, GGT, ALP, and bilirubin. In the exploratory laparotomy a highly vascularized abdominal mass in the left hypochondrium region of approximately 50cm x 45cm x 30cm, adhered to the surrounding structures was observed. Due to the size and adhesions to the omentum, the mass was considered surgically unresectable, and euthanasia was performed followed by necropsy. The immunohistochemical and morphological results indicate the diagnosis of myofibrosarcoma since the neoplastic cells immunoexpressed Vimentin, HHF35 and S100. To the authors' knowledge, this is the first equine case of omental myofibrosarcoma described in the literature.

O miofibrossarcoma em cavalos é um raro tumor maligno, composto predominantemente por miofibroblastos. Um equino, de 15 anos de idade, foi encaminhado ao Hospital Veterinário da Universidade Federal do Paraná, para avaliação de sinais de cólica. O exame clínico inicial apresentou mucosas ictéricas e, nos exames laboratoriais, revelou anemia e aumento sérico de ALT, GGT, ALP e bilirrubina. Na laparotomia exploratória, observou-se massa abdominal vascularizada de aproximadamente 50cm x 45cm x 30cm na região do hipocôndrio esquerdo e aderida às estruturas circunvizinhas. Devido ao tamanho e às aderências ao omento, a massa foi considerada irressecável cirurgicamente, portanto foi realizada a eutanásia e a necropsia. Os resultados imuno-histoquímicos e morfológicos indicam o diagnóstico de miofibrossarcoma, visto que as células neoplásicas imunoexpressaram Vimentin, HHF35 e S100. Portanto, esse é o primeiro caso em equinos de miofibrossarcoma omental descrito na literatura.

Cellular components of the idiopathic epiretinal membrane.

Idiopathic epiretinal membrane (iERM) is a fibrocellular proliferation on the inner surface of the retina, which leads to decreased visual acuity and even central visual loss. As iERM is associated to advanced age and posterior vitreous detachment, a higher prevalence is expected with increasing life expectancy and aging of the global population. Although various cell types of retinal and extra-retinal origin have been described in iERMs (Müller glial cells, astrocytes, hyalocytes, retinal pigment epithelium cells, myofibroblasts, and fibroblasts), myofibroblasts have a central role in collagen production and contractile activity. Thus, myofibroblast differentiation is considered a key event for the iERM formation and progression, and fibroblasts, Müller glial cells, hyalocytes, and retinal pigment epithelium have been identified as myofibroblast precursors. On the other side, the different cell types synthesize growth factors, cytokines, and extracellular matrix, which have a crucial role in ERM pathogenesis. In the present review, the major cellular components and their functions are summarized, and their possible roles in the iERM formation are discussed. By exploring in detail the cellular and molecular aspects of iERM, we seek to contribute for better understanding of this fibrotic disease and the origin of myofibroblasts, which may eventually drive to more targeted therapeutic approaches.

Myofibroblasts and Fibrosis: Mitochondrial and Metabolic Control of Cellular Differentiation.

Cardiac fibrosis is mediated by the activation of resident cardiac fibroblasts, which differentiate into myofibroblasts in response to injury or stress. Although myofibroblast formation is a physiological response to acute injury, such as myocardial infarction, myofibroblast persistence, as occurs in heart failure, contributes to maladaptive remodeling and progressive functional decline. Although traditional pathways of activation, such as TGFß (transforming growth factor ß) and AngII (angiotensin II), have been well characterized, less understood are the alterations in mitochondrial function and cellular metabolism that are necessary to initiate and sustain myofibroblast formation and function. In this review, we highlight recent reports detailing the mitochondrial and metabolic mechanisms that contribute to myofibroblast differentiation, persistence, and function with the hope of identifying novel therapeutic targets to treat, and potentially reverse, tissue organ fibrosis.

Intraglomerular Monocyte/Macrophage Infiltration and Macrophage-Myofibroblast Transition during Diabetic Nephropathy Is Regulated by the A2B Adenosine Receptor.

Diabetic nephropathy (DN) is considered the main cause of kidney disease in which myofibroblasts lead to renal fibrosis. Macrophages were recently identified as the major source of myofibroblasts in a process known as macrophage-myofibroblast transition (MMT). Adenosine levels increase during DN and in vivo administration of MRS1754, an antagonist of the A2B adenosine receptor (A2BAR), attenuated glomerular fibrosis (glomerulosclerosis). We aimed to investigate the association between A2BAR and MMT in glomerulosclerosis during DN. Kidneys/glomeruli of non-diabetic, diabetic, and MRS1754-treated diabetic (DM+MRS1754) rats were processed for histopathologic, transcriptomic, flow cytometry, and cellular in vitro analyses. Macrophages were used for in vitro cell migration/transmigration assays and MMT studies. In vivo MRS1754 treatment attenuated the clinical and histopathological signs of glomerulosclerosis in DN rats. Transcriptomic analysis demonstrated a decrease in chemokine-chemoattractants/cell-adhesion genes of monocytes/macrophages in DM+MRS1754 glomeruli. The number of intraglomerular infiltrated macrophages and MMT cells increased in diabetic rats. This was reverted by MRS1754 treatment. In vitro cell migration/transmigration decreased in macrophages treated with MRS1754. Human macrophages cultured with adenosine and/or TGF-ß induced MMT, a process which was reduced by MRS1754. We concluded that pharmacologic blockade of A2BAR attenuated some clinical signs of renal dysfunction and glomerulosclerosis, and decreased intraglomerular macrophage infiltration and MMT in DN rats.

Diabetes alters the involvement of myofibroblasts during periodontal wound healing.

OBJECTIVES: Myofibroblasts constitute a specific cell phenotype involved in connective tissue healing. Diabetes alters the wound healing response. However, it is not clear whether diabetes modifies the involvement of myofibroblasts in periodontal wounds. MATERIALS AND METHODS: Type I diabetes was induced in rats through streptozotocin injection, and periodontal wounds were performed. Wound healing was evaluated histologically at 2, 5, 7, and 15 days by measuring epithelial migration, neutrophil infiltration, and collagen and biofilm formation. Distribution of myofibroblasts was evaluated through immunofluorescence for α-smooth muscle actin. Data analyses were performed using the Shapiro-Wilk, ANOVA, or Kruskal-Wallis tests. RESULTS: Diabetic wounds were characterized by delayed epithelial closure, increased neutrophil infiltration, biofilm formation, and reduced collagen formation. Quantification of the myofibroblasts showed a significant reduction at 5 and 7 days in wounds of diabetic rats and an increase at 15 days when compared to wounds of non-diabetic rats. CONCLUSIONS: Diabetic wound healing was associated with decreased epithelial and connective tissue healing, increased levels of inflammation, and biofilm formation. Myofibroblast differentiation was delayed in diabetic periodontal wounds at early time points. However, myofibroblasts persisted at later time points of healing. The present study suggests that diabetes alters the involvement of myofibroblasts during periodontal wound healing.

Pro-fibrotic effect of oxidized LDL in cardiac myofibroblasts.

Inflammatory signals associated with cardiac diseases trigger trans-differentiation of cardiac fibroblasts to cardiac myofibroblasts. Cardiac myofibroblasts are the main cell type involved in the development of cardiac fibrosis, a diffuse and disproportionate accumulation of collagen in the myocardium. Although the role of the scavenger like-lectin receptor LOX-1 was previously investigated in cardiac fibroblasts and fibrosis, the involvement of the LOX-1 ligand -oxidized low-density lipoprotein (oxLDL)- on cardiac myofibroblast function still remains unexplored. In the present work, we investigated the effect of oxLDL/LOX-1 on fibrotic markers and cardiac myofibroblast function. Our in vitro results showed that oxLDL increased cardiac myofibroblast proliferation, triggered an increase in the synthesis of collagen type I and fibronectin containing extra domain A, and stimulated collagen type I secretion. oxLDL also decreased cardiac myofibroblast migration, collagen gel contraction and cell area, without modifying α-smooth muscle actin protein levels. These effects were dependent on LOX-1, because LOX-1 knockdown abolished oxLDL effects. Collectively these data showed that oxLDL has important modulatory effects on cardiac myofibroblast function.

Stevia prevents experimental cirrhosis by reducing hepatic myofibroblasts and modulating molecular profibrotic pathways.

AIM: The aims of the present study were to investigate the capacity of stevia leaves to prevent experimental cirrhosis induced by chronic administration of carbon tetrachloride (CCl4 ) in rats and to explore the action mechanism involved. METHODS: Liver cirrhosis was established by CCl4 treatment (400 mg/kg i.p. three times a week for 12 weeks); stevia powder was administered (100 mg/kg by gavage daily) during the CCl4 treatment. Serum markers of liver damage and hydroxyproline were evaluated and histopathological analyses were carried out. The profibrotic pathways were analyzed by western blot and immunohistochemistry. RESULTS: We found for the first time that stevia cotreatment prevented the elevation of serum markers of necrosis and cholestasis and the occurrence of liver fibrosis. It is worth noting that stevia downregulated several profibrogenic pathways, including the reduction of hepatic myofibroblasts and decreased matrix metalloproteinase (MMP)2 and MMP13 expression, thereby blocking the liberation of transforming growth factor-ß from the extracellular matrix. Notably, stevia reduced the phosphorylation of pSmad3L, the most profibrogenic and mitogenic Smad, by inhibiting the activation of c-Jun N-terminal kinase and extracellular signal-regulated kinase. Interestingly, Smad7, an important antifibrotic molecule, was upregulated by stevia treatment in cirrhotic rats. These multitarget mechanisms led to the prevention of experimental cirrhosis. CONCLUSIONS: Because stevia possesses a reasonable safety profile, our results indicate that it could be useful in the clinical setting to treat chronic liver diseases.

Myofibroblastic lesions in the oral cavity: Immunohistochemical and ultrastructural analysis.

OBJECTIVE: To immunohistochemically characterize a group of oral myofibroblastic lesions (MLs) and to evaluate the ultrastructural features of myofibroblasts. MATERIAL AND METHODS: Using a tissue microarray technique (TMA), cases of myofibroma (MF), of nodular fasciitis (NF), of desmoplastic fibroma (DF), and of myofibroblastic sarcoma (MS) from the Universidad Autónoma Metropolitana Xochimilco, and a Private Oral Pathology Service in Mexico City were stained with antibodies against alpha-smooth muscle actin (α-SMA), H-caldesmon, vimentin, desmin, ß-catenin, CD34, anaplastic lymphoma protein kinase (ALK-1), and Ki-67. RESULTS: Nineteen of the 22 MF cases, 2/5 of the NF cases, 1/10 of the DF cases, and 1/2 of the MS cases were positive for α-SMA. 1/2 of the MS cases were positive for desmin; 6/10 of the DF cases were positive for ß-catenin, and 2 of the MF cases were positive for ALK-1. All of the MLs were positive for vimentin and negative for H-caldesmon and CD-34. The Ki-67 labeling index in all of the 8/22 MF, 3/5 NF, and 2/2 MS cases was ≥10%. For all of the MLs evaluated, ultrastructural analysis revealed spindle-shaped cells containing endoplasmic reticulum and peripheral actin filament bundles. CONCLUSION: In certain myofibroblastic lesions, the use of auxiliary techniques (such as immunohistochemistry) can be critical for differential diagnosis.

Effects of cyclosporin, nifedipine and phenytoin on gingival myofibroblast transdifferentiation in monkeys

Abstract Objective: Myofibroblasts have been associated with the development of several pathologic fibrotic conditions. This longitudinal study aims to assess the proliferative and antiapoptotic effects of cyclosporin, nifedipine and phenytoin on gingival connective tissue cells of nonhuman primate, as well as to analyze a possible role of myofibroblasts in gingival overgrowth. Materials and Methods: Gingival samples from the right superior canine area were obtained from 12 male monkeys ( Sapajus spp ) to comprise the control group. After one week, the animals were randomly assigned to three groups, which received daily oral doses of cyclosporin, nifedipine or phenytoin for 120 days. Gingival samples were collected from the left superior canine area of two animals of each group at 52 and 120 days. Histological sections were stained with hematoxylin and eosin, and immunoreacted against α-SMA, Ki- 67 and bcl-2. Results: α-SMA immunoreaction was negative in the control and experimental groups. Similarly, no difference between groups concerning immunostaining against Ki-67 and bcl-2 was observed in connective tissue cells. Conclusion: Based on this methodology, it may be concluded that gingival overgrowths induced by cyclosporin, nifedipine and phenytoin are not associated with neither myofibroblast transdifferentiation, proliferation nor apoptosis of gingival connective cells in monkeys.

Acute lung injury by gastric fluid instillation: activation of myofibroblast apoptosis during injury resolution.

BACKGROUND: Gastric contents aspiration in humans has variable consequences depending on the volume of aspirate, ranging from subclinical pneumonitis to respiratory failure with up to 70% mortality. Several experimental approaches have been used to study this condition. In a model of single orotracheal instillation of gastric fluid we have shown that severe acute lung injury evolves from a pattern of diffuse alveolar damage to one of organizing pneumonia (OP), that later resolves leaving normal lung architecture. Little is known about mechanisms of injury resolution after a single aspiration that could be dysregulated with repetitive aspirations. We hypothesized that, in a similar way to cutaneous wound healing, apoptosis may participate in lung injury resolution by reducing the number of myofibroblasts and by affecting the balance between proteases and antiproteases. Our aim was to study activation of apoptosis as well as MMP-2/TIMP-2 balance in the sub-acute phase (4-14 days) of gastric fluid-induced lung injury. METHODS: Anesthesized Sprague-Dawley rats received a single orotracheal instillation of gastric fluid and were euthanized 4, 7 and 14 days later (n = 6/group). In lung tissue we studied caspase-3 activation and its location by double immunofluorescence for cleaved caspase-3 or TUNEL and alpha-SMA. MMP-2/TIMP-2 balance was studied by zymography and Western blot. BALF levels of TGF-ß1 were measured by ELISA. RESULTS: An OP pattern with Masson bodies and granulomas was seen at days 4 and 7 that was no longer present at day 14. Cleaved caspase-3 increased at day 7 and was detected by immunofluorescence in Masson body-alpha-SMA-positive and -negative cells. TUNEL-positive cells at days 4 and 7 were located mainly in Masson bodies. Distribution of cleaved caspase-3 and TUNEL-positive cells at day 14 was similar to that in controls. At the peak of apoptosis (day 7), an imbalance between MMP-2 activity and TIMP-2 expression was produced by reduction in TIMP-2 expression. CONCLUSIONS: Apoptosis is activated in Masson body-alpha-SMA-positive and -negative cells during the sub-acute phase of gastric fluid-induced lung injury. This mechanism likely contributes to OP resolution, by reducing myofibroblast number and new collagen production. In addition, pre-formed collagen degradation is favored by an associated MMP-2/TIMP-2 imbalance.

Myofibroblasts in oral potentially malignant disorders: Is it related to malignant transformation?

In oral cancer, acquisition of α-smooth muscle actin (α-SMA)-positive fibroblasts, known as myofibroblasts or carcinoma-associated fibroblasts (CAF), is an important event for progression and metastasis. However, the contribution of myofibroblasts in oral potentially malignant disorders (OPMD) remains controversial. This systematic review provides evidence that immunodetection of myofibroblasts may identify oral submucous fibrosis (OSMF) with high risk of malignant transformation, but does not represent an auxiliary tool to predict the malignant potential of leukoplakia and erythroplakia, the most common OPMD.

Altered MicroRNA Expression Is Responsible for the Pro-Osteogenic Phenotype of Interstitial Cells in Calcified Human Aortic Valves.

BACKGROUND: The transition of aortic valve interstitial cells (AVICs) to myofibroblastic and osteoblast-like phenotypes plays a critical role in calcific aortic valve disease progression. Several microRNAs (miRs) are implicated in stem cell differentiation into osteoblast. We hypothesized that an epigenetic mechanism regulates valvular pro-osteogenic activity. This study examined miR profile in AVICs of calcified valves and identified miRs responsible for AVIC phenotypic transition. METHODS AND RESULTS: AVICs were isolated from normal and diseased valves. The miR microarray analysis revealed 14 upregulated and 12 downregulated miRs in diseased AVICs. Increased miR-486 and decreased miR-204 levels were associated with higher levels of myofibroblastic biomarker α-smooth muscle actin and osteoblastic biomarkers runt-related transcription factor 2 (Runx2) and osterix (Osx). Cotransfection of miR-486 antagomir and miR-204 mimic in diseased AVICs reduced their ability to express Runx2 and Osx. The miR-486 mimic upregulated α-smooth muscle actin expression in normal AVICs through the protein kinase B pathway and moderately elevated Runx2 and Osx levels. Knockdown of α-smooth muscle actin attenuated Runx2 and Osx expression induced by miR-486. The miR-486 mimic and miR-204 antagomir synergistically promoted Runx2 and Osx expression and calcium deposition in normal AVICs and normal aortic valve tissue. CONCLUSIONS: In AVICs of calcified valves, increased levels of miR-486 induce myofibroblastic transition to upregulate Runx2 and Osx expression and synergize with miR-204 deficiency to elevate cellular and valvular pro-osteogenic activity. These novel findings indicate that modulation of the epigenetic mechanism underlying valvular pro-osteogenic activity has therapeutic potential for prevention of calcific aortic valve disease progression.

Presence of Telocytes in a Non-innervated Organ: The Placenta.

This chapter discusses the relationship between failure in placentation and the subsequent alterations in the normal structure of the placenta. Interstitial Cajal-like cells (ICLC) were observed for the first time in the human placenta in 2007 and later were named telocytes. Strong evidence confirms that in the placental chorionic villi, TC are located strategically between the smooth muscle cells (SMC) of the fetal blood vessel wall and the stromal myofibroblasts. As the placenta is a non-innervated organ and considering the strategic position of telocytes in chorionic villi, it has been postulated that their function would be related to signal transduction mechanisms involved in the regulation of the blood flow in the fetal vessels, as well as in the shortening/lengthening of the chorionic villi providing the necessary rhythmicity to the process of maternal/fetal metabolic exchange. In this context, telocytes represent part of a functional triad: "SMC of fetal blood vessel-telocyte-myofibroblast." This triad takes part in the regulation of fetal growth and development via transport of nutrients and gases. This chapter also discusses the alterations in the metabolic maternal-fetal exchange, leading to intrauterine growth retardation and preeclampsia. Additionally, the apoptosis undergoing in the preeclamptic hypoxic placenta affects all the chorionic villi cells, including telocytes and myofibroblast, and not only trophoblast, as it has been so far considered. In consequence, we proposed that apoptosis affects the triad structure and alters the placental function, subsequently affecting the normal fetal growth and development.