Proliferation Of Kidney Fibroblasts Research Articles

Transcription factor Twist1 drives fibroblast activation to promote kidney fibrosis via signaling proteins Prrx1/TNC3

The transcription factor Twist1 plays a vital role in normal development in many tissue systems and continues to be important throughout life. However, inappropriate Twist1 activity has been associated with kidney injury and fibrosis, though the underlying mechanisms involved remain incomplete. Here, we explored the role of Twist1 in regulating fibroblast behaviors and the development kidney fibrosis. Initially Twist1 protein and activity was found to be markedly increased within interstitial myofibroblasts in fibrotic kidneys in both humans and rodents. Treatment of rat kidney interstitial fibroblasts with transforming growth factor-β1 (a profibrotic factor) also induced Twist1 expression in vitro. Gain- and loss-of-function experiments supported that Twist1 signaling was responsible for transforming growth factor-β1-induced fibroblast activation and fetal bovine serum-induced fibroblast proliferation. Mechanistically, Twist1 protein promoted kidney fibroblast activation by driving the expression of downstream signaling proteins, Prrx1 and TNC. Twist1 directly enhanced binding to the promoter of Prrx1 but not TNC, whereas the promoter of TNC was directly bound by Prrx1. Finally, mice with fibroblast-specific deletion of Twist1 exhibited less Prrx1 and TNC protein abundance, interstitial extracellular matrix deposition and kidney inflammation in both the unilateral ureteral obstruction and ischemic-reperfusion injury-induced kidney fibrotic models. Inhibition of Twist1 signaling with Harmine, a β-carboline alkaloid, improved extracellular matrix deposition in both injury models. Thus, our results suggest that Twist1 signaling promotes the activation and proliferation of kidney fibroblasts, contributing to the development of interstitial fibrosis, offering a potential therapeutic target for chronic kidney disease.

腎線維化時に発現上昇するleupaxinは腎線維芽細胞の増殖を制御する

腎線維化時に発現上昇するleupaxinは腎線維芽細胞の増殖を制御する

Dihydroartemisinin attenuates renal fibrosis through regulation of fibroblast proliferation and differentiation

AimsRenal fibrosis is the most common final stage of progressive renal disease, characterized by fibroblast proliferation, fibroblast-to-myofibroblast differentiation and excessive accumulation of extracellular matrix. Dihydroartemisinin (DHA) exerts antitumor, antibacterial, and antifibrotic effects. The aim of this study was to determine whether DHA has beneficial effects on unilateral ureteral obstruction (UUO)-induced renal fibrosis in mice and to examine explore the underlying possible mechanisms. Materials and methodsEight-week-old male C57BL/6 mice were intragastrically administered DHA for 14 consecutive days after UUO operation. Afterward, interstitial collagen deposition, expression of collagen I and III, fibronectin, α-smooth muscle actin (α-SMA), proliferating cell nuclear antigen (PCNA), and S100 calcium-binding protein A4 (S100A4) were assessed in the kidneys. Transforming growth factor beta 1 (TGF-β1)-induced primary human kidney fibroblasts were treated with DHA to further investigate the mechanism underlying its action. Key findingsIn vivo, DHA reduced UUO-induced morphological and pathological changes and the degree of renal fibrosis. In addition, DHA mitigated fibroblast proliferation and differentiation in kidney tissue induced by UUO. In vitro, DHA significantly attenuated the TGF-β1-induced primary human kidney fibroblast proliferation and fibroblast-to-myofibroblast differentiation. Moreover, treatment with DHA attenuated the up-regulation of phosphorylation of phosphatidylinositol-3-kinase (PI3K) and protein kinase B (AKT) in UUO model and TGF-β1-induced primary human kidney fibroblasts. SignificanceWe provide in vivo and in vitro evidence that DHA may relieve renal fibrosis through regulation of fibroblast proliferation and differentiation by mitigating the PI3K/AKT pathway. DHA may potentially be used as a therapeutic antifibrotic agent for the treatment of renal fibrosis.

Yap/Taz Deletion in Gli+ Cell-Derived Myofibroblasts Attenuates Fibrosis

In damaged kidneys, increased extracellular matrix (ECM) and tissue stiffness stimulate kidney fibrosis through incompletely characterized molecular mechanisms. The transcriptional coactivators yes-associated protein (Yap) and transcriptional coactivator with PDZ-binding motif (Taz) function as mechanosensors in cancer cells and have been implicated in the regulation of myofibroblasts in the kidney. We hypothesized that the development of kidney fibrosis depends on Yap-induced activation and proliferation of kidney fibroblasts. In mice, Yap expression increased in renal fibroblasts after unilateral ureteral obstruction (UUO), in association with worsening of interstitial fibrosis. In cultured fibroblasts, inhibition of Yap/Taz signaling blocked TGF-β1-induced fibroblast-to-myofibroblast transformation and ECM production, whereas constitutive activation of Yap promoted fibroblast transformation and ECM production even in the absence of TGF-β1. Moreover, in the absence of TGF-β1, fibroblasts seeded on a stiffened ECM transformed into myofibroblasts in a process dependent on the activation of Yap. In mice with UUO, the Yap inhibitor verteporfin reduced interstitial fibrosis. Furthermore, Gli1+ cell-specific knockout of Yap/Taz in mice suppressed UUO-induced ECM deposition, myofibroblast accumulation, and interstitial fibrosis. In a UUO-release model, induction of Gli1+ cell-specific Yap/Taz knockout partially reversed the development of interstitial fibrosis. Thus, in the kidney, Yap is a tissue mechanosensor that can be activated by ECM and transforms fibroblasts into myofibroblasts; the interaction of Yap/Taz and ECM forms a feed-forward loop resulting in kidney fibrosis. Identifying mechanisms that interrupt this profibrotic cycle could lead to the development of anti-fibrosis therapy.

Sonic hedgehog is a novel tubule-derived growth factor for interstitial fibroblasts after kidney injury.

Tubular epithelium constitutes the majority of the renal parenchyma and is the primary target of various kidney injuries. However, how the injured tubules drive interstitial fibroblast activation and proliferation remains poorly understood. Here, we investigated the role of sonic hedgehog (Shh), a secreted extracellular signaling protein, in fibroblast proliferation. Shh was induced in renal tubular epithelia in animal models of CKD induced by ischemia/reperfusion injury (IRI), adriamycin, or renal mass ablation, and in renal tubules of kidney biopsy specimens from CKD patients with different etiologies. Using Gli1-CreER(T2) reporter mice, we identified interstitial fibroblasts as the principal targets of renal Shh signaling in vivo. In vitro, incubation with Shh promoted normal rat kidney fibroblast proliferation, which was assessed by cell counting, MTT assay, and BrdU incorporation assay, and stimulated the induction of numerous proliferation-related genes. However, Shh had no effect on the proliferation of renal tubular epithelial cells. In vivo, overexpression of Shh promoted fibroblast expansion and aggravated kidney fibrotic lesions after IRI. Correspondingly, blockade of Shh signaling by cyclopamine, a small molecule inhibitor of Smoothened, inhibited fibroblast proliferation, reduced myofibroblast accumulation, and attenuated renal fibrosis. These studies identify Shh as a novel, specific, and potent tubule-derived growth factor that promotes interstitial fibroblast proliferation and activation. Our data also suggest that blockade of Shh signaling is a plausible strategy for therapeutic intervention of renal fibrosis.

Dual role of acetaminophen in promoting hepatoma cell apoptosis and kidney fibroblast proliferation

Acetaminophen (APAP), is a safe analgesic and antipyretic drug at therapeutic dose, and is widely used in the clinic. However, high doses of APAP can induce hepatotoxicity and nephrotoxicity. Most studies have focused on high-dose APAP-induced acute liver and kidney injury. So far, few studies have investigated the effects of the therapeutic dose (1/10 of the high dose) or of the low dose (1/100 of the high dose) of APAP on the cells. The aim of this study was to investigate the cellular effects of therapeutic- or low-dose APAP treatment on hepatoma cells and kidney fibroblasts. As expected, high-dose APAP treatment inhibited while therapeutic and low-dose treatment did not inhibit cell survival of kidney tubular epithelial cells. In addition, therapeutic-dose treatment induced an increase in the H2O2 level, activated the caspase-9/-3 cascade, and induced cell apoptosis of hepatoma cells. Notably, APAP promoted fibroblast proliferation, even at low doses. This study demonstrates that different cellular effects are exerted upon treatment with different APAP concentrations. Our results indicate that treatment with the therapeutic dose of APAP may exert an antitumor activity on hepatoma, while low-dose treatment may be harmful for patients with fibrosis, since it may cause proliferation of fibroblasts.

Early treatment of Aicardi syndrome with vigabatrin can improve outcome

Tubular epithelium constitutes the majority of the renal parenchyma and is the primary target of various kidney injuries. However, how the injured tubules drive interstitial fibroblast activation and proliferation remains poorly understood. Here, we investigated the role of sonic hedgehog (Shh), a secreted extracellular signaling protein, in fibroblast proliferation. Shh was induced in renal tubular epithelia in animal models of CKD induced by ischemia/reperfusion injury (IRI), adriamycin, or renal mass ablation, and in renal tubules of kidney biopsy specimens from CKD patients with different etiologies. Using Gli1-CreER^T2 reporter mice, we identified interstitial fibroblasts as the principal targets of renal Shh signaling <i>in vivo</i>. <i>In vitro</i>, incubation with Shh promoted normal rat kidney fibroblast proliferation, which was assessed by cell counting, MTT assay, and BrdU incorporation assay, and stimulated the induction of numerous proliferation-related genes. However, Shh had no effect on the proliferation of renal tubular epithelial cells. <i>In vivo</i>, overexpression of Shh promoted fibroblast expansion and aggravated kidney fibrotic lesions after IRI. Correspondingly, blockade of Shh signaling by cyclopamine, a small molecule inhibitor of Smoothened, inhibited fibroblast proliferation, reduced myofibroblast accumulation, and attenuated renal fibrosis. These studies identify Shh as a novel, specific, and potent tubule-derived growth factor that promotes interstitial fibroblast proliferation and activation. Our data also suggest that blockade of Shh signaling is a plausible strategy for therapeutic intervention of renal fibrosis.

Mitogenic signaling of urokinase receptor-deficient kidney fibroblasts: actions of an alternative urokinase receptor and LDL receptor-related protein.

The urokinase receptor (uPAR) attenuates myofibroblast recruitment and fibrosis in the kidney. This study examined the role of uPAR and its co-receptor LDL receptor-related protein (LRP) in the regulation of kidney fibroblast proliferation and extracellular signal-regulated kinase (ERK) signaling. Compared with uPAR+/+ cells, uPAR-/- kidney fibroblasts were hyperproliferative. UPAR-/- fibroblast proliferation was 60% inhibited by an ERK kinase inhibitor. LRP protein was reduced and extracellular accumulation of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) proteins were greater in uPAR-/- cultures. Addition of functional uPA protein or LRP antisense RNA significantly increased ERK signaling and cell mitosis in both genotypes. Enhanced uPAR-/- fibroblast proliferation was reversed by a recombinant nonfunctional uPA peptide. The density of cell-bound fluor-uPA was similar between uPAR-/- and uPAR+/+ fibroblasts (78 +/- 6 versus 92 +/- 16 units). These data suggest that uPAR-deficient kidney fibroblasts express lower levels of its scavenger co-receptor LRP, resulting in greater extracellular accumulation of uPA and PAI-1. Enhanced proliferation of uPAR-/- fibroblasts seems to be mediated by uPA-dependent ERK signaling via an alternative urokinase receptor.

Morphine modulates proliferation of kidney fibroblasts

Renal interstitial scarring is an important component of heroin-associated nephropathy. Kidney fibroblasts have been demonstrated to play a role in the development of renal scarring in a variety of renal diseases. We studied the effect of morphine, an active metabolite of heroin, on the proliferation of kidney fibroblasts. Morphine at a concentration of 10(-12) M enhanced (P < 0.001) the proliferation of kidney fibroblasts (control, 67.5 +/- 2.0 vs. morphine, 112.2 +/- 10.1 x 10(4) cells/well). [3H]thymidine incorporation studies further confirmed these results. Morphine at concentrations of 10(-12) M to 10(-10) M also modulated mRNA expression of early growth related genes (c-fos, c-jun and c-myc). Morphine at concentrations of 10(-8) to 10(-4) M promoted apoptosis of kidney fibroblasts and also enhanced the synthesis of p53 by kidney fibroblasts. We speculate that morphine-induced kidney fibroblast proliferation may be mediated through the activation of early growth related genes, whereas morphine induced kidney fibroblast apoptosis may be mediated through the generation of p53. The present in vitro study provides a hypothetical basis for the role of morphine in the development of renal interstitial scarring in patients with heroin-associated nephropathy.

Cell-mediated immunity in interstitial nephritis. III. T lymphocyte-mediated fibroblast proliferation and collagen synthesis: an immune mechanism for renal fibrogenesis.

Fibroblast proliferation and collagen synthesis play an important role in the progression of intersititial nephritis. To evaluate the involvement of immune mechanisms in this process, we induced intersititial nephritis in guinea pigs utilizing injections of tubular antigens. Over a 3-week period, injected animals developed a nephritis characterized by mononuclear infiltrates and expanding areas of fibrotic scar formation. Involved kidneys contained increased collagen as compared to controls. To identify mediators of the observed fibrogenesis, T lymphocytes from nephritic and control animals were stimulated with soluble tubular antigens. Dialyzed supernatants from control lymphocyte cultures contained an inhibitor of both fibroblast proliferation and collagen synthesis. In contrast, supernatants from nephritic animals demonstrated absence of inhibition and a progressively increasing titer of a factor that enhanced both kidney fibroblast proliferation and collagen synthesis. As the disease progressed, however, nephritic lymphocytes also began secreting an inhibitor of proliferation that could be detected in low levels. These studies suggest, therefore, that immune mechanisms and altered lymphocyte function may play an important role in the development, progression, and regulation of renal fibrogenesis in intersititial nephritis.