Role for α3 integrin in EMT and pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive (myo)fibroblast accumulation and collagen deposition. One possible source of (myo)fibroblasts is epithelial cells that undergo epithelial-mesenchymal transition (EMT), a process frequently mediated by TGF-β. In this issue of the JCI, Kim et al. report that epithelial cell–specific deletion of α3 integrin prevents EMT in mice, thereby protecting against bleomycin-induced fibrosis (see the related article beginning on page 213). The authors propose a novel mechanism linking TGF-β and β-catenin signaling in EMT through integrin-dependent association of tyrosine-phosphorylated β-catenin and pSmad2 and suggest targeted disruption of this interaction as a potential therapeutic approach. Idiopathic pulmonary fibrosis (IPF) is a progressive disorder of unknown etiology characterized by fibroblast accumulation, collagen deposition, and ECM remodeling leading to parenchymal destruction (1). Historically, inflammation has been viewed as central to the pathogenesis of IPF. A recent paradigm shift proposes a model in which injury to the epithelium initiates a proinflammatory and profibrotic cascade, resulting in fibroblast expansion and progressive fibrosis reminiscent of abnormal wound healing (2). Myofibroblasts (activated fibroblasts) are key effector cells in pulmonary fibrosis, being responsible for matrix deposition and structural remodeling. The source of myofibroblasts in IPF remains the subject of debate: in addition to arising from circulating progenitors and resident fibroblasts, myofibroblasts have recently been shown to be derived from alveolar epithelial cells (AECs) through epithelial-mesenchymal transition (EMT) (3, 4).     

Mesenchymal Stem Cells Correct Inappropriate Epithelial–mesenchyme Relation in Pulmonary Fibrosis Using Stanniocalcin-1

Current hypotheses suggest that aberrant wound healing has a critical role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). In these hypotheses, continuous TGF-β1 secretion by alveolar epithelial cells (AECs) in abnormal wound healing has a critical role in promoting fibroblast differentiation into myofibroblasts. Mesenchymal stem cells (MSCs) home to the injury site and reduce fibrosis by secreting multifunctional antifibrotic humoral factors in IPF. In this study, we show that MSCs can correct the inadequate-communication between epithelial and mesenchymal cells through STC1 (Stanniocalcin-1) secretion in a bleomycin-induced IPF model. Inhalation of recombinant STC1 shows the same effects as the injection of MSCs. Using STC1 plasmid, it was possible to enhance the ability of MSCs to ameliorate the fibrosis. MSCs secrete large amounts of STC1 in response to TGF-β1 in comparison to AECs and fibroblasts. The antifibrotic effects of STC1 include reducing oxidative stress, endoplasmic reticulum (ER) stress, and TGF-β1 production in AECs. The STC1 effects can be controlled by blocking uncoupling protein 2 (UCP2) and the secretion is affected by the PI3/AKT/mTORC1 inhibitors. Our findings suggest that STC1 tends to correct the inappropriate epithelial–mesenchymal relationships and that STC1 plasmid transfected to MSCs or STC1 inhalation could become promising treatments for IPF.     

Macrophage-derived netrin-1 drives adrenergic nerve–associated lung fibrosis

Fibrosis is a macrophage-driven process of uncontrolled extracellular matrix accumulation. Neuronal guidance proteins such as netrin-1 promote inflammatory scarring. We found that macrophage-derived netrin-1 stimulates fibrosis through its neuronal guidance functions. In mice, fibrosis due to inhaled bleomycin engendered netrin-1–expressing macrophages and fibroblasts, remodeled adrenergic nerves, and augmented noradrenaline. Cell-specific knockout mice showed that collagen accumulation, fibrotic histology, and nerve-associated endpoints required netrin-1 of macrophage but not fibroblast origin. Adrenergic denervation; haploinsufficiency of netrin-1’s receptor, deleted in colorectal carcinoma; and therapeutic α₁ adrenoreceptor antagonism improved collagen content and histology. An idiopathic pulmonary fibrosis (IPF) lung microarray data set showed increased netrin-1 expression. IPF lung tissues were enriched for netrin-1⁺ macrophages and noradrenaline. A longitudinal IPF cohort showed improved survival in patients prescribed α₁ adrenoreceptor blockade. This work showed that macrophages stimulate lung fibrosis via netrin-1–driven adrenergic processes and introduced α₁ blockers as a potentially new fibrotic therapy.     

Targeting the αv integrin/TGF-β axis improves natural killer cell function against glioblastoma stem cells

Glioblastoma multiforme (GBM), the most aggressive brain cancer, recurs because glioblastoma stem cells (GSCs) are resistant to all standard therapies. We showed that GSCs, but not normal astrocytes, are sensitive to lysis by healthy allogeneic natural killer (NK) cells in vitro. Mass cytometry and single-cell RNA sequencing of primary tumor samples revealed that GBM tumor–infiltrating NK cells acquired an altered phenotype associated with impaired lytic function relative to matched peripheral blood NK cells from patients with GBM or healthy donors. We attributed this immune evasion tactic to direct cell-to-cell contact between GSCs and NK cells via αv integrin–mediated TGF-β activation. Treatment of GSC-engrafted mice with allogeneic NK cells in combination with inhibitors of integrin or TGF-β signaling or with TGFBR2 gene–edited allogeneic NK cells prevented GSC-induced NK cell dysfunction and tumor growth. These findings reveal an important mechanism of NK cell immune evasion by GSCs and suggest the αv integrin/TGF-β axis as a potentially useful therapeutic target in GBM.     

Polydatin ameliorates pulmonary fibrosis by suppressing inflammation and the epithelial mesenchymal transition via inhibiting the TGF-β/Smad signaling pathway

Pulmonary fibrosis is a chronic and progressive lung disease which results in a loss of pulmonary function and eventually respiratory failure. Inflammation and epithelial mesenchymal transition (EMT) play important roles in the pathogenesis of pulmonary fibrosis. This study aimed to investigate the therapeutic effect of polydatin (PD) in bleomycin-induced pulmonary fibrosis. A bleomycin-induced pulmonary fibrosis animal model used SD rats. Morphological changes were analyzed by hematoxylin-eosin staining. RT-qPCR and western blot were used for the detection of the expression of TGF-β1, collagen I, collagen III, E-cadherin, fibronectin and the ratios of p-Smad2/Smad2, p-Smad3/Smad3. The concentrations of PICP, PIIINP, TNF-α, IL-1β, IL-6 and IL-17 were measured by enzyme linked immunosorbent assay (Elisa) assay. Results showed that PD attenuated bleomycin-induced pulmonary fibrosis. The beneficial effect of PD was possibly related to the inhibition of inflammation and EMT through suppressing the TGF-β/Smad signaling pathway. Our findings suggested that PD might be a potential therapeutic candidate in the treatment of pulmonary fibrosis.

Pulmonary fibrosis is a chronic and progressive lung disease which results in a loss of pulmonary function and eventually respiratory failure.     

Retracted Article: TMEM88 inhibits fibrosis in renal proximal tubular epithelial cells by suppressing the transforming growth factor-β1/Smad signaling pathway

Transmembrane protein 88 (TMEM88) belongs to a member of the TMEM family, and was reported to be involved in fibrogenesis. However, the biological role of TMEM88 in renal fibrosis has not been elucidated. Therefore, the objective of this study was to investigate the effect of TMEM88 on cell proliferation and extracellular matrix (ECM) accumulation in a TGF-β1-induced human renal proximal tubular epithelial cell line (HK2). Our results showed that TMEM88 was downregulated in renal fibrotic tissues and TGF-β1-treated HK2 cells. In addition, TMEM88 overexpression inhibited TGF-β1-induced cell proliferation and migration in HK2 cells. Furthermore, TMEM88 overexpression reduced the production of α-SMA, collagen I, and collagen III in TGF-β1-stimulated HK2 cells. Mechanistically, TMEM88 overexpression suppressed the phosphorylation status of Smad2 and Smad3 in TGF-β1-stimulated HK2 cells. In conclusion, data from our experiments demonstrate that TMEM88 plays a pivotal role in the pathological process of renal fibrosis. TMEM88 inhibited fibrosis in renal proximal tubular epithelial cells by suppressing the TGF-β1/Smad signaling pathway.

Transmembrane protein 88 (TMEM88) belongs to a member of the TMEM family, and was reported to be involved in fibrogenesis.     

A Role for Endogenous Transforming Growth Factor β1 in Langerhans Cell Biology: The Skin of Transforming Growth Factor β1 Null Mice Is Devoid of Epidermal Langerhans Cells

Transforming growth factor β1 (TGF-β1) regulates leukocytes and epithelial cells. To determine whether the pleiotropic effects of TGF-β1, a cytokine that is produced by both keratinocytes and Langerhans cells (LC), extend to epidermal leukocytes, we characterized LC (the epidermal contingent of the dendritic cell [DC] lineage) and dendritic epidermal T cells (DETC) in TGF-β1 null (TGF-β1 −/−) mice. I-A⁺ LC were not detected in epidermal cell suspensions or epidermal sheets prepared from TGF-β1 −/− mice, and epidermal cell suspensions were devoid of allostimulatory activity. In contrast, TCR-γδ⁺ DETC were normal in number and appearance in TGF-β1 −/− mice and, importantly, DETC represented the only leukocytes in the epidermis. Immunolocalization studies revealed CD11c⁺ DC in lymph nodes from TGF-β1 −/− mice, although gp40⁺ DC were absent. Treatment of TGF-β1 −/− mice with rapamycin abrogated the characteristic inflammatory wasting syndrome and prolonged survival indefinitely, but did not result in population of the epidermis with LC. Thus, the LC abnormality in TGF-β1 −/− mice is not a consequence of inflammation in skin or other organs, and LC development is not simply delayed in these animals. We conclude that endogenous TGF-β1 is essential for normal murine LC development or epidermal localization.     

Integrin α2β1 regulates collagen I tethering to modulate hyperresponsiveness in reactive airway disease models

Severe asthma remains challenging to manage and has limited treatment options. We have previously shown that targeting smooth muscle integrin α₅β₁ interaction with fibronectin can mitigate the effects of airway hyperresponsiveness by impairing force transmission. In this study, we show that another member of the integrin superfamily, integrin α₂β₁, is present in airway smooth muscle and capable of regulating force transmission via cellular tethering to the matrix protein collagen I and, to a lesser degree, laminin-111. The addition of an inhibitor of integrin α₂β₁ impaired IL-13–enhanced contraction in mouse tracheal rings and human bronchial rings and abrogated the exaggerated bronchoconstriction induced by allergen sensitization and challenge. We confirmed that this effect was not due to alterations in classic intracellular myosin light chain phosphorylation regulating muscle shortening. Although IL-13 did not affect surface expression of α₂β₁, it did increase α₂β₁-mediated adhesion and the level of expression of an activation-specific epitope on the β₁ subunit. We developed a method to simultaneously quantify airway narrowing and muscle shortening using 2-photon microscopy and demonstrated that inhibition of α₂β₁ mitigated IL-13–enhanced airway narrowing without altering muscle shortening by impairing the tethering of muscle to the surrounding matrix. Our data identified cell matrix tethering as an attractive therapeutic target to mitigate the severity of airway contraction in asthma.     

Catenin α 1 mutations cause familial exudative vitreoretinopathy by overactivating Norrin/β-catenin signaling

Familial exudative vitreoretinopathy (FEVR) is a severe retinal vascular disease that causes blindness. FEVR has been linked to mutations in several genes associated with inactivation of the Norrin/β-catenin signaling pathway, but these account for only approximately 50% of cases. We report that mutations in α-catenin (CTNNA1) cause FEVR by overactivating the β-catenin pathway and disrupting cell adherens junctions. We identified 3 heterozygous mutations in CTNNA1 (p.F72S, p.R376Cfs*27, and p.P893L) by exome sequencing and further demonstrated that FEVR-associated mutations led to overactivation of Norrin/β-catenin signaling as a result of impaired protein interactions within the cadherin-catenin complex. The clinical features of FEVR were reproduced in mice lacking Ctnna1 in vascular endothelial cells (ECs) or with overactivated β-catenin signaling by an EC-specific gain-of-function allele of Ctnnb1. In isolated mouse lung ECs, both CTNNA1-P893L and F72S mutants failed to rescue either the disrupted F-actin arrangement or the VE-cadherin and CTNNB1 distribution. Moreover, we discovered that compound heterozygous Ctnna1 F72S and a deletion allele could cause a similar phenotype. Furthermore, in a FEVR family, we identified a mutation of LRP5, which activates Norrin/β-catenin signaling, and the corresponding knockin mice exhibited a partial FEVR-like phenotype. Our study demonstrates that the precise regulation of β-catenin activation is critical for retinal vascular development and provides new insights into the pathogenesis of FEVR.     

WNT1-inducible signaling protein–1 mediates pulmonary fibrosis in mice and is upregulated in humans with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by distorted lung architecture and loss of respiratory function. Enhanced (myo)fibroblast activation, ECM deposition, and alveolar epithelial type II (ATII) cell dysfunction contribute to IPF pathogenesis. However, the molecular pathways linking ATII cell dysfunction with the development of fibrosis are poorly understood. Here, we demonstrate, in a mouse model of pulmonary fibrosis, increased proliferation and altered expression of components of the WNT/β-catenin signaling pathway in ATII cells. Further analysis revealed that expression of WNT1-inducible signaling protein–1 (WISP1), which is encoded by a WNT target gene, was increased in ATII cells in both a mouse model of pulmonary fibrosis and patients with IPF. Treatment of mouse primary ATII cells with recombinant WISP1 led to increased proliferation and epithelial-mesenchymal transition (EMT), while treatment of mouse and human lung fibroblasts with recombinant WISP1 enhanced deposition of ECM components. In the mouse model of pulmonary fibrosis, neutralizing mAbs specific for WISP1 reduced the expression of genes characteristic of fibrosis and reversed the expression of genes associated with EMT. More importantly, these changes in gene expression were associated with marked attenuation of lung fibrosis, including decreased collagen deposition and improved lung function and survival. Our study thus identifies WISP1 as a key regulator of ATII cell hyperplasia and plasticity as well as a potential therapeutic target for attenuation of pulmonary fibrosis.     

Blocking follistatin-like 1 attenuates bleomycin-induced pulmonary fibrosis in mice

Progressive tissue fibrosis is a cause of major morbidity and mortality. Pulmonary fibrosis is an epithelial-mesenchymal disorder in which TGF-β1 plays a central role in pathogenesis. Here we show that follistatin-like 1 (FSTL1) differentially regulates TGF-β and bone morphogenetic protein signaling, leading to epithelial injury and fibroblast activation. Haplodeletion of Fstl1 in mice or blockage of FSTL1 with a neutralizing antibody in mice reduced bleomycin-induced fibrosis in vivo. Fstl1 is induced in response to lung injury and promotes the accumulation of myofibroblasts and subsequent fibrosis. These data suggest that Fstl1 may serve as a novel therapeutic target for treatment of progressive lung fibrosis.Progressive tissue fibrosis is an increasing cause of morbidity and mortality worldwide with limited therapeutic options. Idiopathic pulmonary fibrosis (IPF), a particularly severe form of lung fibrosis, is a chronic, progressive, and often fatal interstitial lung disease of unknown etiology with a mean survival of 2–3 yr from diagnosis (ATS/ERS, 2000; Olson et al., 2007). The hallmark of IPF is the unremitting extracellular matrix (ECM) deposition with minimal associated inflammation (Noble and Homer, 2004; Wilson and Wynn, 2009). Although evidence suggests that lung fibrosis is an epithelial-mesenchymal disorder (Selman and Pardo, 2002; Chapman, 2011), the mechanisms by which injured epithelium activates fibroblasts/myofibroblasts are unclear. Epithelial apoptosis pathways are activated in the lungs of patients with acute lung injury, in part by activation of signaling pathways such as Fas ligand–Fas and TGF-β (Hagimoto et al., 2002). In addition, the injured alveolar epithelial cells (AECs) may also be abnormally activated with phenotypic changes (King et al., 2011; Kage and Borok, 2012; Yang et al., 2013). The signals required for this activation are unknown. A recent study suggests that injured kidney epithelial cells produce an increased number of TGF-β–containing exosomes to activate fibroblasts (Borges et al., 2013). We hypothesized that injured pulmonary epithelial cells may activate mesenchymal cells by releasing soluble factors to promote a fibrogenic microenvironment.Both TGF-β (Sime et al., 1997; Gauldie et al., 2007) and bone morphogenetic protein (BMP) signaling pathways (Costello et al., 2010) play a role in the initiation and progression of fibrosis. They regulate both epithelial cell injury and fibroblast proliferation and transdifferentiation into myofibroblasts at the injury site (Leask and Abraham, 2004; Selman et al., 2008; Goodwin and Jenkins, 2009). BMP4 antagonists have been implicated in fibrotic disorders of multiple organs including lung (Dolan et al., 2003; Patella et al., 2006; Costello et al., 2010). The precise mechanisms of TGF-β superfamily members in regulating lung fibrogenesis in specific cell types are largely unclear.Follistatin-like 1 (FSTL1), initially identified as a TGF-β–inducible gene (Shibanuma et al., 1993), encodes a small secreted glycoprotein belonging to a group of matricellular proteins. We recently reported that Fstl1 acts as a BMP4 antagonist to play a key role in lung development (Geng et al., 2011). The role of FSTL1 in lung fibrosis has not been investigated. In this study, we have interrogated the role of FSTL1-regulated TGF-β/BMP signaling in different cell types during lung injury and fibrosis. We report that FSTL1 mediates epithelial-mesenchymal communication at the cellular level. We found that FSTL1 modulated TGF-β but not BMP signaling, leading to fibroblast activation. We provide evidence that targeting FSTL1 may offer a novel therapeutic approach for patients with progressive tissue fibrosis.     

Increased local expression of coagulation factor X contributes to the fibrotic response in human and murine lung injury

Uncontrolled activation of the coagulation cascade contributes to the pathophysiology of several conditions, including acute and chronic lung diseases. Coagulation zymogens are considered to be largely derived from the circulation and locally activated in response to tissue injury and microvascular leak. Here we report that expression of coagulation factor X (FX) is locally increased in human and murine fibrotic lung tissue, with marked immunostaining associated with bronchial and alveolar epithelia. FXa was a potent inducer of the myofibroblast differentiation program in cultured primary human adult lung fibroblasts via TGF-β activation that was mediated by proteinase-activated receptor–1 (PAR1) and integrin α_vβ₅. PAR1, α_vβ₅, and α-SMA colocalized to fibrotic foci in lung biopsy specimens from individuals with idiopathic pulmonary fibrosis. Moreover, we demonstrated a causal link between FXa and fibrosis development by showing that a direct FXa inhibitor attenuated bleomycin-induced pulmonary fibrosis in mice. These data support what we believe to be a novel pathogenetic mechanism by which FXa, a central proteinase of the coagulation cascade, is locally expressed and drives the fibrotic response to lung injury. These findings herald a shift in our understanding of the origins of excessive procoagulant activity and place PAR1 central to the cross-talk between local procoagulant signaling and tissue remodeling.     

Long non-coding (lnc)RNA profiling and the role of a key regulator lnc-PNRC2-1 in the transforming growth factor-β1-induced epithelial–mesenchymal transition of CNE1 nasopharyngeal carcinoma cells

ObjectivesTo identify key long non-coding (lnc)RNAs responsible for the epithelial–mesenchymal transition (EMT) of CNE1 nasopharyngeal carcinoma cells and to investigate possible regulatory mechanisms in EMT.MethodsCNE1 cells were divided into transforming growth factor (TGF)-β1-induced EMT and control groups. The mRNA and protein expression of EMT markers was determined by real-time quantitative PCR and western blotting. Differentially expressed genes (DEGs) between the two groups were identified by RNA sequencing analysis, and DEG functions were analyzed by gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses. EMT marker expression was re-evaluated by western blotting after knockdown of a selected lncRNA.ResultsTGF-β1-induced EMT was characterized by decreased E-cadherin and increased vimentin, N-cadherin, and Twist expression at both mRNA and protein levels. Sixty lncRNA genes were clustered in a heatmap, and mRNA expression of 14 dysregulated lncRNAs was consistent with RNA sequencing. Knockdown of lnc-PNRC2-1 increased expression of its antisense gene MYOM3 and reduced expression of EMT markers, resembling treatment with the TGF-β1 receptor inhibitor LY2109761.ConclusionVarious lncRNAs participated indirectly in the TGF-β1-induced EMT of CNE1 cells. Lnc-PNRC2-1 may be a key regulator of this and is a potential target to alleviate CNE1 cell EMT.     

miR-21 mediates fibrogenic activation of pulmonary fibroblasts and lung fibrosis

Uncontrolled extracellular matrix production by fibroblasts in response to tissue injury contributes to fibrotic diseases, such as idiopathic pulmonary fibrosis (IPF), a progressive and ultimately fatal process that currently has no cure. Although dysregulation of miRNAs is known to be involved in a variety of pathophysiologic processes, the role of miRNAs in fibrotic lung diseases is unclear. In this study, we found up-regulation of miR-21 in the lungs of mice with bleomycin-induced fibrosis and also in the lungs of patients with IPF. Increased miR-21 expression was primarily localized to myofibroblasts. Administration of miR-21 antisense probes diminished the severity of experimental lung fibrosis in mice, even when treatment was started 5–7 d after initiation of pulmonary injury. TGF-β1, a central pathological mediator of fibrotic diseases, enhanced miR-21 expression in primary pulmonary fibroblasts. Increasing miR-21 levels promoted, whereas knocking down miR-21 attenuated, the pro-fibrogenic activity of TGF-β1 in fibroblasts. A potential mechanism for the role of miR-21 in fibrosis is through regulating the expression of an inhibitory Smad, Smad7. These experiments demonstrate an important role for miR-21 in fibrotic lung diseases and also suggest a novel approach using miRNA therapeutics in treating clinically refractory fibrotic diseases, such as IPF.Fibroblast proliferation and generation of provisional extracellular matrix (ECM) are primary tissue responses to injury (Tomasek et al., 2002). Successful wound repair processes are tightly regulated, with a balance of ECM synthesis and resolution as well as reepithelization (Tomasek et al., 2002). Uncontrolled ECM production can lead to clinically important fibrotic diseases, including idiopathic pulmonary fibrosis (IPF) (Tomasek et al., 2002; Thannickal et al., 2004). An important pathological feature of IPF is the presence of fibroblastic foci in the lungs, and the presence and extent of such fibroblastic foci is one of the most reliable markers of poor prognosis in patients with IPF (Wynn, 2007; Hardie et al., 2009). Fibroblastic foci are aggregations of fibroblasts/myofibroblasts that produce excessive ECM components (Wynn, 2007; Hardie et al., 2009). TGF-β1 has been shown to be an important mediator of lung fibrosis and can induce differentiation of pulmonary fibroblasts into myofibroblasts characterized by α-smooth muscle actin (α-SMA) expression and active synthesis of ECM proteins (Lee et al., 2006; Cutroneo et al., 2007).microRNAs (miRNAs) are a class of noncoding small RNAs, 22 nt in length, which bind to the 3′ UTR of target genes and thereby repress translation of target genes and/or induce degradation of target gene mRNA (Stefani and Slack, 2008). miRNAs play essential roles in numerous cellular and developmental processes, including intracellular signaling pathways and organ morphogenesis (Stefani and Slack, 2008). Aberrant expression of miRNAs is closely associated with initiation and progression of pathophysiologic processes including diabetes, cancer, and cardiovascular disease (Thum et al., 2008; Croce, 2009; Latronico and Condorelli, 2009; Pandey et al., 2009). However, the role of miRNAs in lung fibrosis is just beginning to unravel (Pandit et al., 2010). Therefore, determining the roles of specific miRNAs involved in the pathogenesis of lung fibrosis is likely to suggest important new directions for the treatment of IPF and other interstitial lung diseases.In the present study, we explored the role of miRNA in the pathogenesis and progression of lung fibrosis. We found that miR-21 is highly up-regulated in the lungs of mice with bleomycin-induced lung fibrosis and in the lungs of patients with IPF. The enhanced expression of miR-21 is primarily located to myofibroblasts in the fibrotic lungs. In addition, miR-21 is up-regulated by TGF-β1 and functions in an amplifying circuit to enhance the fibrogenic activity of TGF-β1 in human primary fibroblasts. More importantly, we found that miR-21 sequestration in mouse lungs attenuates bleomycin-induced lung fibrosis. Overall, these data suggest that miR-21 is a central mediator in the pathogenesis of lung fibrosis and a potential target for developing novel therapeutics in treating fibrotic diseases, including IPF.     

Transforming Growth Factor β Production Is Inversely Correlated with Severity of Murine Malaria Infection

We have examined the role of the immunomodulatory cytokine transforming growth factor (TGF)-β in the resolution and pathology of malaria in BALB/c mice. Circulating levels of TGF-β, and production of bioactive TGF-β by splenocytes, were found to be low in lethal infections with Plasmodium berghei. In contrast, resolving infections with P. chabaudi chabaudi or P. yoelii were accompanied by significant TGF-β production. A causal association between the failure to produce TGF-β and the severity of malaria infection was demonstrated by treatment of infected mice with neutralizing antibody to TGF-β, which exacerbated the virulence of P. berghei and transformed a resolving P. chabaudi chabaudi infection into a lethal infection, but had little effect on the course of P. yoelii infection. Parasitemia increased more rapidly in anti–TGF-β–treated mice but this did not seem to be the explanation for the increased pathology of infection as peak parasitemias were unchanged. Treatment of P. berghei–infected mice with recombinant TGF-β (rTGF-β) slowed the rate of parasite proliferation and prolonged their survival from 15 to up to 35 d. rTGF-β treatment was accompanied by a significant decrease in serum tumor necrosis factor α and an increase in interleukin 10. Finally, we present evidence that differences in TGF-β responses in different malaria infections are due to intrinsic differences between species of malaria parasites in their ability to induce production of TGF-β. Thus, TGF-β seems to induce protective immune responses, leading to slower parasite growth, early in infection, and, subsequently, appears to downregulate pathogenic responses late in infection. This duality of effect makes TGF-β a prime candidate for a major immunomodulatory cytokine associated with successful control of malaria infection.     

Integrin-mediated type II TGF-β receptor tyrosine dephosphorylation controls SMAD-dependent profibrotic signaling

Tubulointerstitial fibrosis underlies all forms of end-stage kidney disease. TGF-β mediates both the development and the progression of kidney fibrosis through binding and activation of the serine/threonine kinase type II TGF-β receptor (TβRII), which in turn promotes a TβRI-mediated SMAD-dependent fibrotic signaling cascade. Autophosphorylation of serine residues within TβRII is considered the principal regulatory mechanism of TβRII-induced signaling; however, there are 5 tyrosine residues within the cytoplasmic tail that could potentially mediate TβRII-dependent SMAD activation. Here, we determined that phosphorylation of tyrosines within the TβRII tail was essential for SMAD-dependent fibrotic signaling within cells of the kidney collecting duct. Conversely, the T cell protein tyrosine phosphatase (TCPTP) dephosphorylated TβRII tail tyrosine residues, resulting in inhibition of TβR-dependent fibrotic signaling. The collagen-binding receptor integrin α1β1 was required for recruitment of TCPTP to the TβRII tail, as mice lacking this integrin exhibited impaired TCPTP-mediated tyrosine dephosphorylation of TβRII that led to severe fibrosis in a unilateral ureteral obstruction model of renal fibrosis. Together, these findings uncover a crosstalk between integrin α1β1 and TβRII that is essential for TβRII-mediated SMAD activation and fibrotic signaling pathways.     

miR-425 suppresses EMT and the development of TNBC (triple-negative breast cancer) by targeting the TGF-β 1/SMAD 3 signaling pathway

Background: EMT has a crucial effect on the progression and metastasis of tumors. This work will elucidate the role of miR-425 in EMT and the development of TNBC. Methods: The differential miRNA expression among non-tumor, para-tumor (adjacent tissue of tumor) and tumor tissues was analyzed. The luciferase activities of TGF-β1 3′UTR treated with miR-425 were determined. Then human breast cancer cell lines were treated with mimics or inhibitors of miR-425, and then the cell proliferation and migration, and invasion ability were assessed. The expression of TGF-β1 and markers of epithelial cells and mesenchymal cells were analyzed. The influences of miR-425 on the development of TNBC through inducing EMT by targeting the TGF-β1/SMAD3 signaling pathway in TNBC cell lines were investigated. Furthermore, xenograft mice were used to explore the potential roles of miR-425 on EMT and the development of TNBC in vivo. Results: Compared with non-tumor tissues, 9 miRNAs were upregulated and 3 miRNAs were down-regulated in tumor tissues. The relative expression of miR-425 in tumor tissues was obviously much lower than that in para-tumor and non-tumor tissues. MiR-425 suppressed TGF-β1 expression, and further inhibited expression of mesenchymal cell markers, while it exerted effects on cell proliferation and migration of TNBC cell lines. Moreover, the agomir of miR-425 could protect against the development process in a murine TNBC xenograft model. Conclusions: Our results demonstrated that miR-425 targets TGF-β1, and was a crucial suppressor on EMT and the development of TNBC through inhibiting the TGF-β1/SMAD3 signaling pathway. This suggests that aiming at the TGF-β1/SMAD3 signaling pathway by enhancing relative miR-425 expression, is a feasible therapy strategy for TNBC.

EMT has a crucial effect on the progression and metastasis of tumors.