NF-κB pathway affects silica nanoparticle-induced fibrosis via inhibited inflammatory response and epithelial-mesenchymal transition in 3D co-culture.

Long-term inhalation of silica nanoparticles (SiNPs) can induce pulmonary fibrosis (PF), nevertheless, the potential mechanisms remain elusive. Herein, we constructed a three-dimensional (3D) co-culture model by using Matrigel to investigate the interaction among different cells and potential regulatory mechanisms after SiNPs exposure. Methodologically, we dynamically observed the changes in cell morphology and migration after exposure to SiNPs by co-culturing mouse monocytic macrophages (RAW264.7), human non-small cell lung cancer cells (A549), and medical research council cell strain-5 (MRC-5) in Matrigel for 24 h. Subsequently, we detected the expression of nuclear factor kappa B (NF-κB), inflammatory factor and epithelial-mesenchymal transition (EMT) markers. The results showed that SiNPs produced toxic effects on cells. In the 3D co-culture state, the cell's movement velocity and displacement increased, and the cell migration ability was enhanced. Meanwhile, the expression of inflammatory factor tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) were upregulated, the epithelial marker E-cadherin (E-cad) was downregulated, the mesenchymal marker N-cadherin (N-cad) and myofibroblast marker alpha-smooth muscle actin (α-SMA) expression were upregulated, while NF-κB expression was also upregulated after SiNPs exposure. We further found that cells were more prone to transdifferentiate into myofibroblasts in the 3D co-culture state. Conversely, utilizing the NF-κB-specific inhibitor BAY 11-7082 effectively downregulated the expression of TNF-α, IL-6, interleukin-1ß (IL-1ß), N-cad, α-SMA, collagen-I (COL I), and fibronectin (FN), the expression of E-cad was upregulated. These findings suggest that NF-κB is involved in regulating SiNPs-induced inflammatory, EMT, and fibrosis in the 3D co-culture state.

Expression of cartilage oligomeric matrix protein in periampullary adenocarcinoma is associated with pancreatobiliary-type morphology, higher levels of fibrosis and immune cell exclusion.

Cartilage oligomeric matrix protein (COMP) is an emerging regulator of tumor progression. The aim of this study was to evaluate the expression of COMP in periampullary adenocarcinoma with respect to prognostic value for survival and relapse, levels of fibrosis and infiltrating immune cells. COMP expression was evaluated using immunohistochemistry in primary tumors and subsets of paired lymph node metastases in tissue microarrays including 175 patients with periampullary adenocarcinoma. Collagen content was assessed with Sirius Red-Fast Green staining. High COMP levels were detected in cancer cells and in stroma, in 46% and 57% of the patients, respectively. High COMP expression was strongly associated with more aggressive pancreatobiliary-type (PB-type) compared to intestinal-type tumors (p < .0001). Importantly, high expression of COMP correlated with the exclusion of cytotoxic T-cells from the cancer cell compartment of the tumors, particularly in PB-type tumors. Higher levels of fibrosis measured by the density of collagen fibers correlated with high COMP levels in both cancer cells and stroma. This in turn could lead to exclusion of cytotoxic T-cells from accessing the cancer cells, a recognized immunotherapy resistance mechanism. Targeting COMP could therefore be considered as a novel therapeutic strategy in PB-type periampullary adenocarcinoma.

Eosinophils participate in modulation of liver immune response and tissue damage induced by Schistosoma mansoni infection in mice.

The severity of chronic schistosomiasis has been mainly associated with the intensity and extension of the inflammatory response induced by egg-secreted antigens in the host tissue, especially in the liver and intestine. During acute schistosomiasis, eosinophils account for approximately 50% of the cells that compose the liver granulomas; however, the role of this cell-type in the pathology of schistosomiasis remains controversial. In the current study, we compared the parasite burden and liver immunopathological changes during experimental schistosomiasis in wild-type (WT) BALB/c mice and BALB/c mice selectively deficient for the differentiation of eosinophils (ΔdblGATA). Our data demonstrated that the absence of eosinophil differentiation did not alter the S. mansoni load or the liver retention of parasite eggs; however, there were significant changes in the liver immune response profile and tissue damage. S. mansoni infection in ΔdblGATA mice resulted in significantly lower liver concentrations of IL-5, IL-13, IL-33, IL-17, IL-10, and TGF-ß and higher concentrations of IFN-γ and TNF-α, as compared to WT mice. The changes in liver immune response observed in infected ΔdblGATA mice were accompanied by lower collagen deposition, but higher liver damage and larger granulomas. Moreover, the absence of eosinophils resulted in a higher mortality rate in mice infected with a high parasite load. Therefore, the data indicated that eosinophils participate in the establishment and/or amplification of liver Th-2 and regulatory response induced by S. mansoni, which is necessary for the balance between liver damage and fibrosis, which in turn is essential for modulating disease severity.

Current Perspectives on the Immunosuppressive Niche and Role of Fibrosis in Hepatocellular Carcinoma and the Development of Antitumor Immunity.

Immune checkpoint inhibitors have become the mainstay of treatment for hepatocellular carcinoma (HCC). However, they are ineffective in some cases. Previous studies have reported that genetic alterations in oncogenic pathways such as Wnt/ß-catenin are the important triggers in HCC for primary refractoriness. T-cell exhaustion has been reported in various tumors and is likely to play a prominent role in the emergence of HCC due to chronic inflammation and cirrhosis-associated immune dysfunction. Immunosuppressive cells including regulatory T-cells and tumor-associated macrophages infiltrating the tumor are associated with hyperprogressive disease in the early stages of immune checkpoint inhibitor treatment. In addition, stellate cells and tumor-associated fibroblasts create an abundant desmoplastic environment by producing extracellular matrix. This strongly contributes to epithelial to mesenchymal transition via signaling activities including transforming growth factor beta, Wnt/ß-catenin, and Hippo pathway. The abundant desmoplastic environment has been demonstrated in pancreatic ductal adenocarcinoma and cholangiocarcinoma to suppress cytotoxic T-cell infiltration, PD-L1 expression, and neoantigen expression, resulting in a highly immunosuppressive niche. It is possible that a similar immunosuppressive environment is created in HCC with advanced fibrosis in the background liver. Although sufficient understanding is required for the establishment of immune therapies of HCC, further investigations are still required in this field.

Molecular Basis of Accelerated Aging with Immune Dysfunction-Mediated Inflammation (Inflamm-Aging) in Patients with Systemic Sclerosis.

Systemic sclerosis (SSc) is a chronic connective tissue disorder characterized by immune dysregulation, chronic inflammation, vascular endothelial cell dysfunction, and progressive tissue fibrosis of the skin and internal organs. Moreover, increased cancer incidence and accelerated aging are also found. The increased cancer incidence is believed to be a result of chromosome instability. Accelerated cellular senescence has been confirmed by the shortening of telomere length due to increased DNA breakage, abnormal DNA repair response, and telomerase deficiency mediated by enhanced oxidative/nitrative stresses. The immune dysfunctions of SSc patients are manifested by excessive production of proinflammatory cytokines IL-1, IL-6, IL-17, IFN-α, and TNF-α, which can elicit potent tissue inflammation followed by tissue fibrosis. Furthermore, a number of autoantibodies including anti-topoisomerase 1 (anti-TOPO-1), anti-centromere (ACA or anti-CENP-B), anti-RNA polymerase enzyme (anti-RNAP III), anti-ribonuclear proteins (anti-U1, U2, and U11/U12 RNP), anti-nucleolar antigens (anti-Th/T0, anti-NOR90, anti-Ku, anti-RuvBL1/2, and anti-PM/Scl), and anti-telomere-associated proteins were also found. Based on these data, inflamm-aging caused by immune dysfunction-mediated inflammation exists in patients with SSc. Hence, increased cellular senescence is elicited by the interactions among excessive oxidative stress, pro-inflammatory cytokines, and autoantibodies. In the present review, we will discuss in detail the molecular basis of chromosome instability, increased oxidative stress, and functional adaptation by deranged immunome, which are related to inflamm-aging in patients with SSc.

E4 engages uPAR and enolase-1 and activates urokinase to exert antifibrotic effects.

Fibroproliferative disorders such as systemic sclerosis (SSc) have no effective therapies and result in significant morbidity and mortality. We recently demonstrated that the C-terminal domain of endostatin, known as E4, prevented and reversed both dermal and pulmonary fibrosis. Our goal was to identify the mechanism by which E4 abrogates fibrosis and its cell surface binding partner(s). Our findings show that E4 activated the urokinase pathway and increased the urokinase plasminogen activator (uPA) to type 1 plasminogen activator inhibitor (PAI-1) ratio. In addition, E4 substantially increased MMP-1 and MMP-3 expression and activity. In vivo, E4 reversed bleomycin induction of PAI-1 and increased uPA activity. In patients with SSc, the uPA/PAI-1 ratio was decreased in both lung tissues and pulmonary fibroblasts compared with normal donors. Proteins bound to biotinylated-E4 were identified as enolase-1 (ENO) and uPA receptor (uPAR). The antifibrotic effects of E4 required uPAR. Further, ENO mediated the fibrotic effects of TGF-ß1 and exerted TGF-ß1-independent fibrotic effects. Our findings suggest that the antifibrotic effect of E4 is mediated, in part, by regulation of the urokinase pathway and induction of MMP-1 and MMP-3 levels and activity in a uPAR-dependent manner, thus promoting extracellular matrix degradation. Further, our findings identify a moonlighting function for the glycolytic enzyme ENO in fibrosis.

Macrophages Modulate the Function of MSC- and iPSC-Derived Fibroblasts in the Presence of Polyethylene Particles.

Fibroblasts in the synovial membrane secrete molecules essential to forming the extracellular matrix (ECM) and supporting joint homeostasis. While evidence suggests that fibroblasts contribute to the response to joint injury, the outcomes appear to be patient-specific and dependent on interactions between resident immune cells, particularly macrophages (Mφs). On the other hand, the response of Mφs to injury depends on their functional phenotype. The goal of these studies was to further explore these issues in an in vitro 3D microtissue model that simulates a pathophysiological disease-specific microenvironment. Two sources of fibroblasts were used to assess patient-specific influences: mesenchymal stem cell (MSC)- and induced pluripotent stem cell (iPSC)-derived fibroblasts. These were co-cultured with either M1 or M2 Mφs, and the cultures were challenged with polyethylene particles coated with lipopolysaccharide (cPE) to model wear debris generated from total joint arthroplasties. Our results indicated that the fibroblast response to cPE was dependent on the source of the fibroblasts and the presence of M1 or M2 Mφs: the fibroblast response as measured by gene expression changes was amplified by the presence of M2 Mφs. These results demonstrate that the immune system modulates the function of fibroblasts; furthermore, different sources of differentiated fibroblasts may lead to divergent results. Overall, our research suggests that M2 Mφs may be a critical target for the clinical treatment of cPE induced fibrosis.

ß-Catenin-NF-κB-CFTR interactions in cholangiocytes regulate inflammation and fibrosis during ductular reaction.

Expansion of biliary epithelial cells (BECs) during ductular reaction (DR) is observed in liver diseases including cystic fibrosis (CF), and associated with inflammation and fibrosis, albeit without complete understanding of underlying mechanism. Using two different genetic mouse knockouts of ß-catenin, one with ß-catenin loss is hepatocytes and BECs (KO1), and another with loss in only hepatocytes (KO2), we demonstrate disparate long-term repair after an initial injury by 2-week choline-deficient ethionine-supplemented diet. KO2 show gradual liver repopulation with BEC-derived ß-catenin-positive hepatocytes and resolution of injury. KO1 showed persistent loss of ß-catenin, NF-κB activation in BECs, progressive DR and fibrosis, reminiscent of CF histology. We identify interactions of ß-catenin, NFκB, and CF transmembranous conductance regulator (CFTR) in BECs. Loss of CFTR or ß-catenin led to NF-κB activation, DR, and inflammation. Thus, we report a novel ß-catenin-NFκB-CFTR interactome in BECs, and its disruption may contribute to hepatic pathology of CF.

The liver has an incredible capacity to repair itself or 'regenerate' ­ that is, it has the ability to replace damaged tissue with new tissue. In order to do this, the organ relies on hepatocytes (the cells that form the liver) and bile duct cells (the cells that form the biliary ducts) dividing and transforming into each other to repair and replace damaged tissue, in case the insult is dire. During long-lasting or chronic liver injury, bile duct cells undergo a process called 'ductular reaction', which causes the cells to multiply and produce proteins that stimulate inflammation, and can lead to liver scarring (fibrosis). Ductular reaction is a hallmark of severe liver disease, and different diseases exhibit ductular reactions with distinct features. For example, in cystic fibrosis, a unique type of ductular reaction occurs at late stages, accompanied by both inflammation and fibrosis. Despite the role that ductular reaction plays in liver disease, it is not well understood how it works at the molecular level. Hu et al. set out to investigate how a protein called ß-catenin ­ which can cause many types of cells to proliferate ­ is involved in ductular reaction. They used three types of mice for their experiments: wild-type mice, which were not genetically modified; and two strains of genetically modified mice. One of these mutant mice did not produce ß-catenin in biliary duct cells, while the other lacked ß-catenin both in biliary duct cells and in hepatocytes. After a short liver injury ­ which Hu et al. caused by feeding the mice a specific diet ­ the wild-type mice were able to regenerate and repair the liver without exhibiting any ductular reaction. The mutant mice that lacked ß-catenin in hepatocytes showed a temporary ductular reaction, and ultimately repaired their livers by turning bile duct cells into hepatocytes. On the other hand, the mutant mice lacking ß-catenin in both hepatocytes and bile duct cells displayed sustained ductular reactions, inflammation and fibrosis, which looked like that seen in patients with liver disease associated to cystic fibrosis. Further probing showed that ß-catenin interacts with a protein called CTFR, which is involved in cystic fibrosis. When bile duct cells lack either of these proteins, another protein called NF-B gets activated, which causes the ductular reaction, leading to inflammation and fibrosis. The findings of Hu et al. shed light on the role of ß-catenin in ductular reaction. Further, the results show a previously unknown interaction between ß-catenin, CTFR and NF-B, which could lead to better treatments for cystic fibrosis in the future.

Role of Transglutaminase 2 in Cell Death, Survival, and Fibrosis.

Transglutaminase 2 (TG2) is a ubiquitously expressed enzyme catalyzing the crosslinking between Gln and Lys residues and involved in various pathophysiological events. Besides this crosslinking activity, TG2 functions as a deamidase, GTPase, isopeptidase, adapter/scaffold, protein disulfide isomerase, and kinase. It also plays a role in the regulation of hypusination and serotonylation. Through these activities, TG2 is involved in cell growth, differentiation, cell death, inflammation, tissue repair, and fibrosis. Depending on the cell type and stimulus, TG2 changes its subcellular localization and biological activity, leading to cell death or survival. In normal unstressed cells, intracellular TG2 exhibits a GTP-bound closed conformation, exerting prosurvival functions. However, upon cell stimulation with Ca2+ or other factors, TG2 adopts a Ca2+-bound open conformation, demonstrating a transamidase activity involved in cell death or survival. These functional discrepancies of TG2 open form might be caused by its multifunctional nature, the existence of splicing variants, the cell type and stimulus, and the genetic backgrounds and variations of the mouse models used. TG2 is also involved in the phagocytosis of dead cells by macrophages and in fibrosis during tissue repair. Here, we summarize and discuss the multifunctional and controversial roles of TG2, focusing on cell death/survival and fibrosis.

Slit2 Inhibits Breast Cancer Metastasis by Activating M1-Like Phagocytic and Antifibrotic Macrophages.

Tumor-associated macrophages (TAM) are heterogeneous in nature and comprise antitumor M1-like (M1-TAM) or pro-tumor M2-like (M2-TAM) TAMs. M2-TAMs are a major component of stroma in breast tumors and enhance metastasis by reducing their phagocytic ability and increasing tumor fibrosis. However, the molecular mechanisms that regulate phenotypic plasticity of TAMs are not well known. Here we report a novel tumor suppressor Slit2 in breast cancer by regulating TAMs in the tumor microenvironment. Slit2 reduced the in vivo growth and metastasis of spontaneous and syngeneic mammary tumor and xenograft breast tumor models. Slit2 increased recruitment of M1-TAMs to the tumor and enhanced the ability of M1-TAMs to phagocytose tumor cells in vitro and in vivo. This Slit2-mediated increase in M1-TAM phagocytosis occurred via suppression of IL6. Slit2 was also shown to diminish fibrosis in breast cancer mouse models by increasing the expression of matrix metalloproteinase 13 in M1-TAMs. Analysis of patient samples showed high Slit2 expression strongly associated with better patient survival and inversely correlated with the abundance of CD163+ TAMs. Overall, these studies define the role of Slit2 in inhibiting metastasis by activating M1-TAMs and depleting tumor fibrosis. Furthermore, these findings suggest that Slit2 can be a promising immunotherapeutic agent to redirect TAMs to serve as tumor killers for aggressive and metastatic breast cancers. In addition, Slit2 expression along with CD163+ TAMs could be used as an improved prognostic biomarker in patients with breast cancer. SIGNIFICANCE: This study provides evidence that the antitumor effect of Slit2 in breast cancer occurs by activating the phagocytic activity of M1-like tumor-associated macrophages against tumor cells and diminishing fibrosis.

The Role of Ageing and Parenchymal Senescence on Macrophage Function and Fibrosis.

In this review, we examine senescent cells and the overlap between the direct biological impact of senescence and the indirect impact senescence has via its effects on other cell types, particularly the macrophage. The canonical roles of macrophages in cell clearance and in other physiological functions are discussed with reference to their functions in diseases of the kidney and other organs. We also explore the translational potential of different approaches based around the macrophage in future interventions to target senescent cells, with the goal of preventing or reversing pathologies driven or contributed to in part by senescent cell load in vivo.

Downregulation of interferon-induced protein with tetratricopeptide repeats 3 relieves the inflammatory response and myocardial fibrosis of mice with myocardial infarction and improves their cardiac function.

Myocardial infarction (MI) is a common cardiovascular disease with high morbidity and mortality. In this study, we explored the role of interferon-induced protein with tetratricopeptide repeats 3 (IFIT3) in MI. MI was induced by ligation of the left anterior descending coronary artery. Lentivirus-mediated RNA interference of IFIT3 expression was performed by tail vein injection 72 h before MI modeling. Cardiac injury indexes and inflammatory response were examined 3 days after MI. Cardiac function indexes, infarct size, and cardiac fibrosis were assessed 4 weeks after MI. IFIT3 expression was upregulated in myocardial tissues at both 3 days and 4 weeks after MI. Knockdown of IFIT3 significantly relieved the myocardial injury, as evidenced by the decrease in serum levels of cTnI and CK-MB. In addition, IFIT3 knockdown significantly reduced the number of CD68+ macrophages and the levels of interleukin-1ß, interleukin-6, and tumor necrosis factor-α, indicating that the inflammatory response was relieved. Moreover, IFIT3 silencing also significantly improved cardiac function and reduced infarct size, myocardial fibrosis, and collagen content in mice with MI. Mechanically, the present study showed that the activation of the mitogen-activated protein kinase (MAPK) pathway was observed in myocardial tissues of MI mice, which was blocked by IFIT3 knockdown, as indicated by the decreased phosphorylation of JNK, p-38, and ERK. Collectively, our results revealed the role of IFIT3 in the inflammatory response and myocardial fibrosis after MI, indicating that IFIT3 might be a potential target for MI treatment.

Immune cells in lens injury repair and fibrosis.

Immune cells, both tissue resident immune cells and those immune cells recruited in response to wounding or degenerative conditions, are essential to both the maintenance and restoration of homeostasis in most tissues. These cells are typically provided to tissues by their closely associated vasculatures. However, the lens, like many of the tissues in the eye, are considered immune privileged sites because they have no associated vasculature. Such absence of immune cells was thought to protect the lens from inflammatory responses that would bring with them the danger of causing vision impairing opacities. However, it has now been shown, as occurs in other immune privileged sites in the eye, that novel pathways exist by which immune cells come to associate with the lens to protect it, maintain its homeostasis, and function in its regenerative repair. Here we review the discoveries that have revealed there are both innate and adaptive immune system responses to lens, and that, like most other tissues, the lens harbors a population of resident immune cells, which are the sentinels of danger or injury to a tissue. While resident and recruited immune cells are essential elements of lens homeostasis and repair, they also become the agents of disease, particularly as progenitors of pro-fibrogenic myofibroblasts. There still remains much to learn about the function of lens-associated immune cells in protection, repair and disease, the knowledge of which will provide new tools for maintaining the core functions of the lens in the visual system.

Genetic and pharmacological inhibition of fatty acid-binding protein 4 alleviated inflammation and early fibrosis after toxin induced kidney injury.

Considerable data have suggested that acute kidney injury (AKI) is often incompletely repaired and could lead to chronic kidney disease (CKD). As we known, toxin-induced nephropathy triggers the rapid production of proinflammatory mediators and the prolonged inflammation allows the injured kidneys to develop interstitial fibrosis. In our previous study, fatty acid-binding protein 4 (Fabp4) has been reported to be involved in the process of AKI. However, whether Fabp4 plays crucial roles in toxin-induced kidney injury remained unclear. To explore the effect and mechanism of Fabp4 on toxin induced kidney injury, folic acid (FA) and aristolochic acid (AA) animal models were used. Both FA and AA injected mice developed severe renal dysfunction and dramatically inflammatory response (IL-6, MCP1 and TNF-a), which further lead to early fibrosis confirmed by the accumulation of extracellular matrix proteins (α-Sma, Fn, Col1 and Col4). Importantly, we found that FA and AA induced-kidney injury triggered the high expression of Fabp4 mRNA/protein in tubular epithelial cells. Furthermore, pharmacological and genetic inhibition of Fabp4 significantly attenuated FA and AA induced renal dysfunction, pathological damage, and early fibrosis via the regulation of inflammation, which is mediated by suppressing p-p65/p-stat3 expression via enhancing Pparγ activity. In summary, Fabp4 in tubular epithelial cells exerted the deleterious effects during the recovery of FA and AA induced kidney injury and the inhibition of Fabp4 might be an effective therapeutic strategy against the progressive AKI.

Mast Cell Involvement in Fibrosis in Chronic Graft-Versus-Host Disease.

Allogeneic hematopoietic stem cell transplantation (HSCT) is most commonly a treatment for inborn defects of hematopoiesis or acute leukemias. Widespread use of HSCT, a potentially curative therapy, is hampered by onset of graft-versus-host disease (GVHD), classified as either acute or chronic GVHD. While the pathology of acute GVHD is better understood, factors driving GVHD at the cellular and molecular level are less clear. Mast cells are an arm of the immune system that are known for atopic disease. However, studies have demonstrated that they can play important roles in tissue homeostasis and wound healing, and mast cell dysregulation can lead to fibrotic disease. Interestingly, in chronic GVHD, aberrant wound healing mechanisms lead to pathological fibrosis, but the cellular etiology driving this is not well-understood, although some studies have implicated mast cells. Given this novel role, we here review the literature for studies of mast cell involvement in the context of chronic GVHD. While there are few publications on this topic, the papers excellently characterized a niche for mast cells in chronic GVHD. These findings may be extended to other fibrosing diseases in order to better target mast cells or their mediators for treatment of fibrotic disease.

Regulatory T Cells Accelerate the Repair Process of Renal Fibrosis by Regulating Mononuclear Macrophages.

BACKGROUND: We aimed to investigate the mechanisms of renal fibrosis and explore the effect of CD4+CD25+Foxp3+ regulatory T cells (Treg) on renal fibrosis after the obstruction was removed. METHODS: Fifty-five C57BL/6 mice were randomly divided into three groups: the unilateral ureteral obstruction (UUO) group, the relief for unilateral ureteral obstruction (RUUO) group, and the RUUO+Treg group. Renal fibrosis indexes of RUUO mice were evaluated using hematoxylin and eosin (HE) and, Masson staining and immunohistochemistry after CD4+CD25+Treg cells were injected into the tail vein at the moment of recanalization. We detected the levels of Treg, M1, and M2 markers by flow cytometry, and the levels of transforming growth factor (TGF)-ß1, interleukin (IL)-1ß, IL-6 and IL-10 using ELISA. RESULTS: The tubular necrosis score, AO value of α-SMA (smooth muscle actin), and collagen area on the 3rd and 14th days post RUUO were up-regulated compared with the 7th day post RUUO (P<0.05). After injection of Treg via tail vein, the tubular necrosis score, AO value of α-SMA, TGF-ß1 level, and collagen area in the RUUO+Treg group on the 14th day were down-regulated compared with the RUUO group (P<0.05). Moreover, Treg could transform M1 macrophages into M2 macrophages, manifesting as up-regulated expression of CD206 compared with the RUUO group (P<0.05). Treg could also down-regulate the secretion of IL-6 and IL-1ß while up-regulating the secretion of IL-10 in vitro compared with the M1 group (P<0.05). CONCLUSIONS: The kidney could deteriorate into a state of injury and fibrosis after the obstruction was removed, and Treg could effectively protect the kidney function.

Proliferative Glomerulonephritis With Fibrils, Monoclonal κ Light Chain, and C3 Deposits.

There is increasing recognition of monoclonal gammopathy as a cause of proliferative glomerulonephritis (GN), including cases in which glomerular deposition of monoclonal immunoglobulin is demonstrated. Recently, proliferative GN with monoclonal immunoglobulin deposits (PGNMID) has incorporated a light chain variant of the disease (termed PGNMID-LC). Intriguingly, glomerular co-deposition of C3 is found in addition to monotypic light chain, implying complement activation via the alternative pathway (AP). We present a unique case of proliferative GN in a 42-year-old man who presented with nephrotic syndrome and was found to have κ light chain multiple myeloma. Immune staining of the glomerulus was positive only for κ light chain and C3, with the striking appearance of nonamyloid fibrils on electron microscopy. Following clonally targeted therapy for myeloma, the renal clinical abnormalities resolved completely. We present detailed molecular studies for light chain and complement and consider local mechanisms whereby monoclonal κ light chain fibrils may have triggered AP activation within the glomerulus.

The evolving cardiac lymphatic vasculature in development, repair and regeneration.

The lymphatic vasculature has an essential role in maintaining normal fluid balance in tissues and modulating the inflammatory response to injury or pathogens. Disruption of normal development or function of lymphatic vessels can have severe consequences. In the heart, reduced lymphatic function can lead to myocardial oedema and persistent inflammation. Macrophages, which are phagocytic cells of the innate immune system, contribute to cardiac development and to fibrotic repair and regeneration of cardiac tissue after myocardial infarction. In this Review, we discuss the cardiac lymphatic vasculature with a focus on developments over the past 5 years arising from the study of mammalian and zebrafish model organisms. In addition, we examine the interplay between the cardiac lymphatics and macrophages during fibrotic repair and regeneration after myocardial infarction. Finally, we discuss the therapeutic potential of targeting the cardiac lymphatic network to regulate immune cell content and alleviate inflammation in patients with ischaemic heart disease.

Fibrocytes: A Critical Review and Practical Guide.

Fibrocytes are hematopoietic-derived cells that directly contribute to tissue fibrosis by producing collagen following injury, during disease, and with aging. The lack of a fibrocyte-specific marker has led to the use of multiple strategies for identifying these cells in vivo. This review will detail how past studies were performed, report their findings, and discuss their strengths and limitations. The motivation is to identify opportunities for further investigation and promote the adoption of best practices during future study design.

The fibrotic and immune microenvironments as targetable drivers of metastasis.

Although substantial progress has been made over the past 40 years in treating patients with cancer, effective therapies for those who are diagnosed with advanced metastatic disease are still few and far between. Cancer cells do not exist in isolation: rather, they exist within a complex microenvironment composed of stromal cells and extracellular matrix. Within this tumour microenvironment exists an interplay between the two main stromal cell subtypes, cancer-associated fibroblasts (CAFs) and immune cells, that are important in controlling metastasis. A complex network of paracrine signalling pathways between CAFs, immune cells and tumour cells are involved at multiple stages of the metastatic process, from invasion and intravasation at the primary tumour site to extravasation and colonisation in the metastatic site. Heterogeneity and plasticity within stromal cell populations also contribute to the complexity. Although many of these processes are likely to be common to a number of metastatic sites, we will describe in detail the interplay within the liver, a preferred site of metastasis for many tumours. A greater understanding of these networks provides opportunities for the design of new therapeutic approaches for targeting the metastatic disease.