Monocyte-derived fibrocytes elimination had little contribution on liver fibrosis

Background:Monocyte-derived fibrocytes play an important role in the progression of fibrosis in the skin,lungs,heart and kidney.However,the contribution of fibrocytes to liver fibrosis is unclear.The aim of this study was to investigate whether fibrocytes contributed to fibrosis progression in the livers of carbon tetrachloride(CCl 4)-treated mice.Methods:C57BL/6J mice were divided into 4 groups:normal control group,CCl 4-treated group,CCl 4+control liposome-treated group,and CCl 4+clodronate liposome-treated group.For the elimination of systemic monocyte and monocyte-derived fibrocyte,one group was treated with clodronate liposome,and another group with control liposome as a control.After 4 weeks of treatment,hepatic mononuclear cells were subjected to immunofluorescent(IF)staining and fluorescence-activated cell sorter(FACS)analysis to detect fibrocytes.Measurement of collagen-positive Sirius red stained area and collagen-I mRNA expression in the liver were performed to evaluate the degree of liver fibrosis quantitatively.Results:In the liver of the CCl 4-treated and CCl 4+control liposome-treated groups,the number of fibrocytes,the area positive for Sirius red staining and collagen-I mRNA expression significantly increased compared with those in the normal control group.In the liver of the CCl 4+clodronate liposome-treated group,few fibrocytes was observed as in the normal control group,but Sirius red staining positive area and collagen-I mRNA expression were increased and equivalent to the CCl 4-treated and CCl 4+control liposome-treated groups.Conclusion:Monocyte-derived fibrocytes play a minimal role in CCl 4-induced liver fibrosis.Cells other than fibrocytes such as hepatic stellate cells play a central role in liver fibrosis.

Crystalline Silica Promotes Rat Fibrocyte Differentiation in Vitro,and Fibrocytes Participate in Silicosis in Vivo

Objective The aim of this study was to investigate the effects of Si O2 on fibrocytes and whether fibrocytes participate in silicosis in vivo. Methods A macrophagocyte（AM）/fibrocyte coculture system was established, and AMs were treated with 100 μg/mL SiO 2. Flow cytometry was used to detect the number of fibrocytes. Real‐time PCR was performed to measure the expression of collagen I, collagen III, and α‐SMA mR NA. The levels of collagen I, collagen III, and TGF‐β1 protein were determined by ELISA. Immunohistochemical staining was performed to measure α‐SMA protein expression. A rat silicosis model was induced by intratracheal instillation of SiO 2. Lung histopathological evaluation was conducted using HE and Masson＇s trichrome staining after 1 and 9 weeks. The number of fibrocytes in peripheral blood or lung tissue of rat was detected by flow cytometry. Double‐color immunofluorescence was applied to identify fibrocytes in the lung tissue. Results Peripheral blood monocytes were found to differentiate into fibrocytes in vitro in a time‐dependent manner, and exposure to crystalline silica might potentiate fibrocyte differentiation. In addition, fibrocytes were able to migrate from peripheral blood to the lung tissue, and the number of fibrocytes was increased after SiO 2 exposure. Conclusion Silica exposure potentiates fibrocyte differentiation, and fibrocytes may participate in silicosis in vivo.

Role of Circulating Fibrocytes in Cardiac Fibrosis

Objective： It is revealed that circulating fibrocytes are elevated in patients/animals with cardiac fibrosis, and this review aims to provide an introduction to circulating fibrocytes and their role in cardiac fibrosis.Data Sources： This review is based on the data from 1994 to present obtained from PubMed.The search terms were ＆quot;circulating fibrocytes＆quot; and ＆quot;cardiac fibrosis＆quot;.Study Selection： Articles and critical reviews, which are related to circulating fibrocytes and cardiac fibrosis, were selected.Results： Circulating fibrocytes, which are derived from hematopoietic stem cells, represent a subset of peripheral blood mononuclear cells exhibiting mixed morphological and molecular characteristics ofhematopoietic and mesenchymal cells （CD34＋/CD45＋/collagen I＋）.They can produce extracellular matrix and many cytokines.It is shown that circulating fibrocytes participate in many fibrotic diseases, including cardiac fibrosis.Evidence accumulated in recent years shows that aging individuals and patients with hypertension, heart failure, coronary heart disease, and atrial fibrillation have more circulating fibrocytes in peripheral blood and/or heart tissue, and this elevation of circulating fibrocytes is correlated with the degree of fibrosis in the hearts.Conclusions： Circulating fibrocytes are effector cells in cardiac fibrosis.

Pathogenetic and prognostic roles of bloodborne fibrocytes in asthma

Bloodborne fibrocytes are cells mobilized from the bone marrow, which express surface antigens commonly ascribed to hematopoietic progenitors and have phenotypic and functional characteristics similar to those of immature mesenchymal cells. They exhibit predominant proinflammatory or profibrotic activities at tissue sites, depending on the host＇s response to environmental insults and on the characteristics of the cell infiltrate and cytokine milieu. In patients with allergic asthma, fibrocytes egress from the bone marrow and are recruited into the airways after every allergen exposure and during viral infections. Recruited fibrocytes amplify the inflammatory responses driven by T helper type 2 lymphokines and favor viral replication and further inflammation on respiratory virus infections. Persistently elevated blood fibrocyte counts and persisting airway fibrocytosis are present in patients with chronically undertreated or corticosteroid-insensitive asthma, and are linked to an enhanced risk of adverse outcomes because of the major involvement of fibrocytes in the development of structural abnormalities that lead to chronic airflow obstruction in these patients. Consequently, blood fibrocyte count is an emerging biomarker of asthma control and disease progression and its clinical applicability as a new outcome measure deserves further evaluation in large clinical trials.

The role of cell mediated immunopathogenesis in thyroid-associated ophthalmopathy

Currently, thyroid-associated ophthalmopathy (TAO) lacks effective treatment due to our lack of clarity in its immunopathogenesis. Orbital fibroblasts play a key role in altering inflammation and immune response in TAO, and are considered as the key target and effector cells in its pathogenesis. The orbit infiltrating CD34+ fibrocytes add on to the process by expressing high levels of autoantigens and inflammatory cytokines, while also differentiating into myofibroblasts or adipocytes. This review focuses on the role of orbital fibroblasts and CD34+ fibrocytes in the pathogenesis of TAO, highlighting the basis of emerging treatments.

Aging promotes pro-fibrotic matrix production and increases fibrocyte recruitment during acute lung injury

Fibrotic lung diseases increase with age. Previously we determined that senescence increases tissue expression of fibronectin EDA (Fn-EDA) and decreases fibroblast expression of Thy-1, and that fibrocytes contribute to fibrosis following bleomycin-induced lung injury in mice. In this study we hypothesized that fibroblasts lacking Thy-1 expression produce an extracellular matrix that promotes fibrocyte retention and myofibroblast transdifferentiation, thereby promoting fibrogenesis. Young and old mice were treated with bleomycin intratracheally;fibrocytes in the bone marrow, blood, and lungs were quantified, and lung fibroblast Thy-1 expression was assessed. Bone marrowderived fibrocytes were cultured on matrices derived from Thy-1(+) or Thy-1(?) fibroblasts ± the pro-fibrotic cytokine TGFβ1. Older mice had more fibrocytes in their bone marrows at baseline and more fibrocytes in their lungs following bleomycin treatment. In parallel, lung fibroblasts in older mice had lower expression of Thy-1 at baseline that increased transiently 7 days after bleomycin treatment but then rapidly waned such that 14 days after bleomycin treatment Thy-1 expression was again markedly lower. Fibrocytes cultured on matrices derived from Thy-1(?) fibroblasts + TGFβ1 had increased gene expression for collagen type 1, fibronectin, Fn-EDA, and α-smooth muscle actin. In parallel, whereas the matrices derived from Thy-1(?) fibroblasts stimulated phosphorylation of Akt in cultured fibrocytes, the matrices derived from Thy-1(+) fibroblasts induced apoptosis. These findings suggest that senescence increases fibrocyte recruitment to the lung following injury and that loss of Thy-1 expression by lung fibroblasts promotes fibrocyte retention and myofibroblast transdifferentiation that renders the “aging lung” susceptible to fibrosis.

Constitutive AKT Activity Predisposes Lung Fibrosis by Regulating Macrophage, Myofibroblast and Fibrocyte Recruitment and Changes in Autophagy

The etiology and pathogenesis of pulmonary fibrosis is poorly understood. We and others reported that M-CSF/CSF-1, M-CSF-R and downstream AKT activation plays an important role in lung fibrosis in mice models and in IPF patients. To understand potential molecular pathways used by M-CSF-R activation to direct lung fibrosis, we used a novel transgenic mouse model that expresses a constitutively-active form of AKT, myristoylated AKT (Myr-Akt), driven by the c-fms (M-CSF-R) promoter. We were particularly interested in the basal immune state of the lungs of these Myr-Akt mice to assess M-CSF-R-related priming for lung fibrosis. In support of a priming effect, macrophages isolated from the lungs of unchallenged Myr-Akt mice displayed an M2-tropism, enhanced co-expression of M-CSF-R and α-SMA, reduced autophagy reflected by reduced expression of the key autophagy genes Beclin-1, MAP1-Lc3a(Lc3a), and MAP1-Lc3b(Lc3b), and increased p62/STSQM1 expression compared with littermate WT mice. Furthermore, Myr-Akt mice had more basal circulating fibrocytes than WT mice. Lastly, upon bleomycin challenge, Myr-Akt mice showed enhanced collagen deposition, increased F4/80+ and CD45+ cells, reduced autophagy genes Beclin-1, Lc3a, and Lc3b expression, and a shorter life-span than WT littermates. These data provide support that M-CSF-R/AKT activation may have a priming effect which can predispose lung tissue to pulmonary fibrosis.

Hematopoietic stem cell-derived adipocytes and fibroblasts in the tumor microenvironment

The tumor microenvironment(TME) is complex and constantly evolving. This is due, in part, to the crosstalk between tumor cells and the multiple cell types that comprise the TME, which results in a heterogeneous population of tumor cells and TME cells. This review will focus on two stromal cell types, the cancerassociated adipocyte(CAA) and the cancer-associated fibroblast(CAF). In the clinic, the presence of CAAs and CAFs in the TME translates to poor prognosis in multiple tumor types. CAAs and CAFs have an activated phenotype and produce growth factors, inflammatory factors, cytokines, chemokines, extracellular matrix components, and proteases in an accelerated and aberrant fashion. Through this activated state, CAAs and CAFs remodel the TME, thereby driving all aspects of tumor progression, including tumor growth and survival, chemoresistance, tumor vascularization, tumor invasion, and tumor cell metastasis. Similarities in the tumorpromoting functions of CAAs and CAFs suggest that a multipronged therapeutic approach may be necessary to achieve maximal impact on disease. While CAAs and CAFs are thought to arise from tissues adjacent to the tumor, multiple alternative origins for CAAs and CAFs have recently been identified. Recent studies from our lab and others suggest that the hematopoietic stem cell, through the myeloid lineage, may serve as a progenitor for CAAs and CAFs. We hypothesize that the multiple origins of CAAs and CAFs may contribute to the heterogeneity seen in the TME. Thus, a better understanding of the origin of CAAs and CAFs, how this origin impacts their functions in the TME, and thetemporal participation of uniquely originating TME cells may lead to novel or improved anti-tumor therapeutics.

Establishment and identification of induced pluripotent stem cells in liver cancer patients

Objective:To induce pluripotent stem(IPS)cells from fibrocytes that are separated from liver cancer patients.Methods:The fibrocytes were reprogrammed to IPS cells by lentiviral vector,stained and identified by immunohistochemistry.Results:The IPS cells were successfully established from fibrocytes after infection,and IPS cell clones formed in round shape under a microscopy.The induction rate was 0.013%±0.007%.No tumor formed at the back of nude mice within 8 weeks after the inoculation of cell clone.However,tetatoma appeared in nude mice within 1 week after IPS inoculation.A few tumors formed in nude mice within 4 weeks after the inoculation of cell clones.However,subcutaneous tumors formed within 1 week after IPS inoculation.The induced IPS cells showed three germ layers in tetatoma.Nanog and OCT4 in the induced IPS cells showed hypomethylation.SSEA-A,TRA-1-6-,TRA-1-81 and Nanog were highly expressed in the induced IPS cells,indicating the IPS cells possessed the similar ability as the stem cells.Conclusion:The IPS cells of liver cancer patients can be established effectively from fibrocytes and can be cultured stably in vitro,which provides an approach for the treatment of intermediate or advanced stage liver cancer.

Potential Role of Interleukin-25/Interleukin-33/Thymic Stromal Lymphopoietin-Fibrocyte Axis in the Pathogenesis of Allergic Airway Diseases

Objective： Allergic airway diseases （AADs） are a group of heterogeneous disease mediated by T-helper type 2 （Th2） immune response and characterized with airway inflammation and remodeling, including allergic asthma, allergic rhinitis, and chronic rhinosinusitis with allergic background. This review aimed to discuss the abnormal epithelial-mesenchymal crosstalk in the pathogenesis of AADs. Data Sources： Articles referred in this review were collected from the database of PubMed published in English up to January 2018. Study Selection： We had done a literature search using the following terms ＂allergic airway disease OR asthma OR allergic rhinitis OR chronic sinusitis AND IL-25 OR IL-33 OR thymic stromal lymphopoietin OR fibrocyte＂. Related original or review articles were included and carefully analyzed. Results： It is now believed that abnormal epithelial-mesenchymal crosstalk underlies the pathogenesis of AADs. However, the key regulatory factors and molecular events involved in this process still remain unclear. Epithelium-derived triple cytokines, including interleukin （IL）-25, IL-33, and thymic stromal lymphopoietin （TSLP）, are shown to act on various target cells and promote the Th2 immune response. Circulating fibrocyte is an important mesenchymal cell that can mediate tissue remodeling. We previously found that IL-25-circulating fibrocyte axis was significantly upregulated in patients with asthma, which may greatly contribute to asthmatic airway inflammation and remodeling. Conclusions： In view of the redundancy ofcytokines and ＂united airway＂ theory, we propose a new concept that IL-25/IL-33/TSLP-fibrocyte axis may play a vital role in the abnormal epithelial-mesenchymal crosstalk in some endotypes of AADs. This novel idea will guide potential new intervention schema for the common treatment of AADs sharing common pathogenesis in the future.