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Fibrosis is a common manifestation of most progressive and degenerative diseases, with myofibroblast activation and matrix accumulation playing a key role. In this issue of the JCI, Hoeft et al. identify the important role of ADAMTS12 in fibroblast activation. ADAMTS12, a secreted protein, is involved in extracellular matrix (ECM) remodeling, cell signaling, and inflammation. ADAMTS12 facilitates proteolysis by cleaving various substrates such as ECM components, which are vital for cellular signaling and remodeling. Additionally, it modulates cell-matrix interactions, influencing cell adhesion and migration, and plays an important role in the inflammatory processes. Understanding the role of ADAMTS12 offers potential therapeutic insights for targeting fibrosis in progressive diseases., Fibrosis in heart and kidney disease Fibrosis is a pathological process characterized by excessive accumulation of extracellular matrix (ECM) components, particularly collagen, in organs, including the heart and kidneys, often [...]

Fibrosis represents the uncontrolled replacement of parenchymal tissue with extracellular matrix (ECM) produced by myofibroblasts. While genetic fate-tracing and single-cell RNA-Seq technologies have helped elucidate fibroblast heterogeneity and ontogeny beyond fibroblast to myofibroblast differentiation, newly identified fibroblast populations remain ill defined, with respect to both the molecular cues driving their differentiation and their subsequent role in fibrosis. Using an unbiased approach, we identified the metalloprotease ADAMTS12 as a fibroblast-specific gene that is strongly upregulated during active fibrogenesis in humans and mice. Functional in vivo KO studies in mice confirmed that Adamts12 was critical during fibrogenesis in both heart and kidney. Mechanistically, using a combination of spatial transcriptomics and expression of catalytically active or inactive ADAMTS12, we demonstrated that the active protease of ADAMTS12 shaped ECM composition and cleaved hemicentin 1 (HMCN1) to enable the activation and migration of a distinct injury- responsive fibroblast subset defined by aberrant high JAK/STAT signaling., Introduction Fibrosis represents the uncontrolled replacement of parenchymal tissue by extracellular matrix (ECM) (1). Whereas deposition of ECM sustains tissue integrity immediately after injury, continued deposition of ECM by myofibroblasts [...]

A trial structural remodeling takes on a critical significance to the occurrence and maintenance of atrial fibrillation (AF). As revealed by recent data, insulin-like growth factor-1 receptor (IGF-1R) plays a certain role in tissue fibrosis. In this study, the mechanism of IGF-1R in atrial structural remodeling was examined based on in vivo and in vitro experiments. First, cluster analysis of AF hub genes was conducted, and then the molecular mechanism was proposed by which IGF-1R regulates myocardial fibrosis via the PI3K/Akt/FoxO3a pathway. Subsequently, the mentioned mechanism was verified in human cardiac fibroblasts (HCFs) and rats transduced with IGF-1 overexpression type 9 adeno-associated viruses. The results indicated that IGF-1R activation up-regulated collagen I protein expression and Akt phosphorylation in HCFs and rat atrium. The administration of LY294002 reversed the above phenomenon, improved the shortening of atrial effective refractory period, and reduced the increased incidence of AF and atrial fibrosis in rats. The transfection of FoxO3a siRNA reduced the anti-fibrotic effect of LY294002 in HCFs. The above data revealed that activation of IGF-1R takes on a vital significance to atrial structural remodeling by facilitating myocardial fibrosis and expediting the occurrence and maintenance of AF through the regulation of the PI3K/Akt/FoxO3a signaling pathway. Key words: atrial fibrillation, atrial structural remodeling, myocardial fibrosis, IGF-1R, PI3K/Akt/FoxO3a pathway, Introduction Atrial fibrillation (AF) refers to the most common rapid arrhythmia in the clinic and the incidence is increasing on a year-to-year basis (Khan et al. 2019). AF increases the [...]

Liver fibrosis is the most common pathway in most types of chronic liver damage, characterized by an imbalance of ECM degradation and synthesis. Saikosaponin-d (SSd) possesses anti-inflammatory and anti-fibrotic effects. However, the underlying mechanism by which SSd represses hepatic stellate cell (HSC) activation remains unclear. Here, we found that SSd remarkably alleviated carbon tetrachloride (C[Cl.sub.4])-induced liver fibrosis, as evidenced by decreased collagen levels and profibrotic marker (COl1a1 and a-smooth muscle actin (SMA)) expression. SSd repressed C[Cl.sub.4]-induced NOD-like receptor family pyrin-domain-containing-3 (NLRP3) activation in fibrotic livers, as suggested by decreased levels of NLRP3, IL-18, and IL-[beta]. The primary HSCs of C[Cl.sub.4] mice exhibited a significant increase in profibrotic marker expression and NLRP3 activation, but SSd treatment reversed this effect. SSd also repressed TGF-[beta]-induced profibrotic marker expression and NLRP3 activation in vitro. Mechanistically, TGF-[beta] decreased the expression of estrogen receptor-[beta] (ER[beta]) in HSCs, whereas SSd treatment reversed this effect. ER[beta] inhibition enhances NLRP3 activation in HSCs. More importantly, ER[beta] or NLRP3 inhibition partially destroyed the function of SSd in liver fibrosis. In summary, the current data suggest that SSd prevents hepatic fibrosis by regulating the ER[beta]/NLRP3 inflammasome pathway and suggests SSd as a potential agent for treating liver fibrosis. Key words: liver fibrosis, saikosaponin-d, NLRP3 inflammasome, estrogen receptor-b, hepatic stellate cells. La fibrose hépatique est la voie finale commune à la plupart des types de lésions hépatiques chroniques, caractérisée par un déséquilibre entre la dégradation et la synthèse de la matrice extracellulaire. La saikosaponine-d (SSd) exerce des effets anti-inflammatoires et anti-fibrose hépatique. Cependant, le mécanisme sous-jacent de la SSd dans la répression de l'activation des cellules de Kupffer (CK) reste obscur. Les auteurs ont découvert ici que le SSd atténue remarquablement la fibrose hépatique induite par le tétrachlorure de carbone (C[Cl.sub.4]), comme en témoigne la diminution du niveau de collagène et de l'expression des marqueurs profibrotiques [COL1A1 et [alpha]-actine de muscle lisse (SMA)]. La SSd réprimait l'activation de la famille des récepteurs NLRP3 (NOD-like receptor family pyrin-domain-containing-3) induite par le C[Cl.sub.4] dans les foies fibreux, comme le suggère la diminution du niveau de NLRP3, IL-18 et IL-[beta]. Les CK primaires de souris traitées au C[Cl.sub.4] présentaient une augmentation significative de l'expression des marqueurs profibrotiques et de l'activation de NLRP3, mais le traitement par SSd inversait cet effet. La SSd réprimait aussi l'expression des marqueurs profibrotiques et l'activation de NLRP3 induites par le TGF-[beta] in vitro. En matière de mécanisme, le TGF-[beta] diminuait l'expression du récepteur d'oestrogène-[beta] (ER[beta]) dans les CK, alors que le traitement par la SSd inversait cet effet. L'inhibition du ERb augmentait l'activation de NLRP3 dans les CK. Qui plus est, l'inhibition du ER[beta] ou de NLRP3 détruisait partiellement la fonction de la SSd contre la fibrose hépatique. En résumé, les données actuelles suggèrent que la SSd prévient la fibrose hépatique en régulant la voie de l'inflammasome ER[beta]/NLRP3, et suggèrent la SSd comme un agent potentiel pour traiter la fibrose hépatique. [Traduit par la Rédaction] Mots-clés : fibrose hépatique, saikosaponine-d, inflammasome NLRP3, récepteur des oestrogènes-[beta], cellules de Kupffer., Introduction Liver fibrosis isthe common pathological basisofvarious chronic liver diseases and is a reversible scar healing response caused by repeated liver injury. Hepatic stellate cells (HSCs) play animportant role in [...]

Fibroblasts are polymorphic cells with pleiotropic roles in organ morphogenesis, tissue homeostasis and immune responses. In fibrotic diseases, fibroblasts synthesize abundant amounts of extracellular matrix, which induces scarring and organ failure. By contrast, a hallmark feature of fibroblasts in arthritis is degradation of the extracellular matrix because of the release of metalloproteinases and degrading enzymes, and subsequent tissue destruction. The mechanisms that drive these functionally opposing pro-fibrotic and pro-inflammatory phenotypes of fibroblasts remain unknown. Here we identify the transcription factor PU.1 as an essential regulator of the pro-fibrotic gene expression program. The interplay between transcriptional and post-transcriptional mechanisms that normally control the expression of PU.1 expression is perturbed in various fibrotic diseases, resulting in the upregulation of PU.1, induction of fibrosis-associated gene sets and a phenotypic switch in extracellular matrix-producing pro-fibrotic fibroblasts. By contrast, pharmacological and genetic inactivation of PU.1 disrupts the fibrotic network and enables reprogramming of fibrotic fibroblasts into resting fibroblasts, leading to regression of fibrosis in several organs. The transcription factor PU.1 is an essential regulator of the pro-fibrotic gene expression program in fibroblasts; PU.1 expression is upregulated in various fibrotic diseases, whereas inactivation of PU.1 induces regression of fibrosis in a number of organs., Author(s): Thomas Wohlfahrt [sup.1] , Simon Rauber [sup.1] , Steffen Uebe [sup.2] , Markus Luber [sup.1] , Alina Soare [sup.1] , Arif Ekici [sup.2] , Stefanie Weber [sup.1] , Alexandru-Emil [...]

Author(s): Sebastian Schafer [1, 2]; Sivakumar Viswanathan [2]; Anissa A. Widjaja [2]; Wei-Wen Lim [1]; Aida Moreno-Moral [2]; Daniel M. DeLaughter [3]; Benjamin Ng [1]; Giannino Patone [4]; Kingsley Chow [...]

Liver fibrosis is a worldwide problem with a significant morbidity and mortality. Cryptolepis sanguinolenta (family Periplocaceae) is widely used in West African countries for the treatment of malaria, as well as for some other diseases. However, the role of C. sanguinolenta in hepatic fibrosis is still unknown. It has been reported that Methyl-CpG binding protein 2 (MeCP2) had a high expression in liver fibrosis and played a central role in its pathobiology. Interestingly, we found that a cryptolepine derivative (HZ-6h) could inhibit liver fibrosis by reducing MeCP2 expression, as evidenced by the dramatic downregulation of a-smooth muscle actin (α-SMA) and type I collagen alpha-1 (Col1α1) in protein levels in vitro. Meanwhile, we also found that HZ-6h could reduce the cell viability and promote apoptosis of hepatic stellate cells (HSCs) treated with transforming growth factor beta l(TGF-β1). Then, we investigated the potential molecular mechanisms and found that HZ-6h blocked Shh signaling in HSC-T6 cells, resulting in the decreased protein expression of Patched-1 (PTCH-1), Sonic hedgehog (Shh), and glioma-associated oncogene homolog 1 (GLI1). In short, these results indicate that HZ-6h inhibits liver fibrosis by downregulating MeCP2 through the Shh pathway in TGF-β1-induced HSC-T6 cells. Key words: cryptolepine, liver fibrosis, Shh signaling, MeCP2. La fibrose hepatique est un probleme mondial qui s'accompagne d'une morbidite et d'une mortalite importantes. Cryptolepsis sanguinolenta (famille des Periplocaceae) est largement utilisee dans les pays de l'Afrique de l'ouest dans le traitement de la malaria ainsi que de quelques autres maladies. Cependant, le role de Cryptolepsis sanguinolenta dans la fibrose hepatique est encore inconnu. Il a ete rapporte qu'une proteine liant le methyl-CpG, la MeCP2, etait fortement exprimee dans la fibrose hepatique et qu'elle jouait un role central dans sa pathobiologie. Fait interessant, les auteurs ont trouve qu'un derive de la cryptolepine (HZ-6h) pouvait inhiber la fibrose hepatique en reduisant l'expression de MeCP2, tel que montre par la regulation a la baisse marquee de l'a-actine du muscle lisse (α-SMA) et du collagene alpha-1 de type I (Collai) au niveau proteique in vitro. En meme temps, les auteurs ont aussi trouve que HZ-6h pouvait reduire la viabilite cellulaire et promouvoir l'apoptose des cellules de Kupffer (CK) traitees au facteur de croissance transformant beta 1 (TGF-β1). Ils ont alors examine les mecanismes moleculaires potentiels et trouve que HZ-6h bloquait la signalisation de Shh dans les cellules HSC-T6, resultant en une diminution de l'expression proteique de Patched-1 (PTCH-1), de Sonic hedgehog (Shh) et du glioma-associated oncogene homolog 1 (GLI1). En bref, ces resultats indiquent que HZ-6h inhibe la fibrose hepatique en regulant a la baisse MeCP2 par l'intermediaire de Shh chez les cellules HSC-T6 induites au TGF-β1. [Traduit par la Redaction] Mots-cles: cryptolepine, fibrose hepatique, signalisation de Shh, MeCP2., Introduction Hepatic fibrosis, a chronic scarring process that is a response to prolonged liver injury induced by hepatitis virus, drugs, toxins, ethanol, autoimmune disorders and so on, is a worldwide [...]

Although the lung can undergo self-repair after injury, fibrosis in chronically injured or diseased lungs can occur at the expense of regeneration. Here we study how a hematopoietic-vascular niche regulates alveolar repair and lung fibrosis. Using intratracheal injection of bleomycin or hydrochloric acid in mice, we show that repetitive lung injury activates pulmonary capillary endothelial cells (PCECs) and perivascular macrophages, impeding alveolar repair and promoting fibrosis. Whereas the chemokine receptor CXCR7, expressed on PCECs, acts to prevent epithelial damage and ameliorate fibrosis after a single round of treatment with bleomycin or hydrochloric acid, repeated injury leads to suppression of CXCR7 expression and recruitment of vascular endothelial growth factor receptor 1 (VEGFR1)-expressing perivascular macrophages. This recruitment stimulates Wnt/p-catenin-dependent persistentupregulation of the Notch ligand Jagged1 (encoded by Jag1) in PCECs, which in turn stimulates exuberant Notch signaling in perivascular fibroblasts and enhances fibrosis. Administration of a CXCR7 agonist or PCEC-targeted Jag1 shRNA after lung injury promotes alveolar repair and reduces fibrosis. Thus, targeting of a maladapted hematopoietic-vascular niche, in which macrophages, PCECs and perivascular fibroblasts interact, may help to develop therapy to spur lung regeneration and alleviate fibrosis., The lung, which facilitates oxygen exchange and defends against inhaled toxicants, is frequently exposed to infectious or noxious injury. Injured lungs can undergo facultative regeneration to restore alveolar architecture and [...]

Hepatic stellate cells (HSCs) play an important role in the process of liver fibrosis. In this study, we investigated the inhibitory effects of capsaicin on HSCs and liver fibrosis. Cultured HSCs were incubated with various concentrations of capsaicin. Cell proliferation was examined using a cell counting kit. Production of hydrogen peroxide was determined using a 2',7'-dichlorofluorescin diacetate (DCFH-DA) assay. The mRNA and protein expression of target genes was analyzed by reverse transcription PCR and Western blot analysis, respectively. Cell apoptosis was evaluated by annexin V-FITC and propidium iodide (PI) costaining followed by flow cytometric analysis. A C[Cl.sub.4] rat liver fibrosis model was used to assess in vivo effects of capsaicin by histological examination and measurement of liver fibrosis markers, including hydroxyproline content, serum type III collagen, and hyaluronic acid (HA) levels. Our results show that capsaicin dose-dependently inhibited cell proliferation, suppressed cell activation, and decreased hydrogen peroxide production in cultured HSCs. Capsaicin reduced the mRNA levels of tissue inhibitors of metalloproteinase 1 (TIMP-1) and transforming growth factor-β1 (TGF-β1) in HSCs. Moreover, capsaicin-induced cell apoptosis was associated with increased expression of Bax, cytochrome c (cyt c), and caspase-3, but reduced levels of Bcl-2. The animal studies further revealed that capsaicin efficiently reduced the extent of liver fibrosis, inhibited HSC proliferation, and promoted cell apoptosis. Our findings suggest that capsaicin might inhibit fibrogenesis by inhibiting the activities of HSCs. Key words: capsaicin, hepatic stellate cells, activation, apoptosis, liver fibrosis. Les cellules hepatiques stellaires (CHS) jouent un role important dans le processus de fibrose hepatique. Ici, les auteurs visaient a examiner les effets inhibiteurs de la capsaicine sur les CHS et la fibrose hepatique. Des CHS en culture ont ete incubees avec differentes concentrations de capsaicine. La proliferation cellulaire a ete examinee a l'aide d'une trousse CCK-8. La production de peroxyde d'hydrogene a ete determinee par un dosage avec le 2',7'-dichlorofluoresceine di-acetate (DCFH-DA). L'expression de l'ARNm et des proteines codes par des genes cibles a ete analyse par reaction en chaine par polymerase couplee a la transcriptase inverse (RT-PCR) et buvardage Western, respectivement. L'apoptose a ete evaluee par coloration a l'annexineV-FITC et l'iodure de propidium (IP) suivie d'une analyse en cytometrie en flux. Un modele de fibrose induite par le C[Cl.sub.4] chez le rat a ete utilise pour evaluer in vivo les effets de la capsaicine, au moyen de l'examen histologique et de la mesure de marqueurs de la fibrose hepatique incluant le contenu en hydroxy-proline, et les niveaux seriques du collagene de type III et d'acide hyaluronique (AH). Les resultats ont montre que la capsaicine inhibait la proliferation en fonction de sa concentration, supprimait l'activation cellulaire et diminuait la production de peroxyde d'hydrogene par les CHS en culture. La capsaicine reduisait les niveaux d'ARNm de l'inhibiteur tissulaire des metallo-proteases-1 (TIMP-1) et du facteur de croissance transformant-β1 (TGF-β1) chez les CHS. De plus, l'apoptose induite par la capsaicine etait associee a un accroissement de l'expression de Bax, du cytochrome c (Cyt-c) et de la caspase 3, mais a une diminution des niveaux de Bcl-2. Les etudes chez l'animal ont revele que la capsaicine reduisait efficacement l'ampleur de la fibrose, inhibait la proliferation des CHS et favorisait l'apoptose. Ces donnees suggerent que la capsaicine pourrait inhiber la fibrogenese en inhibant l'activite des CHS. [Traduit par la Redaction] Mots-cles: capsaicine, cellules hepatiques stellaires, activation, apoptose, fibrose hepatique., Introduction Liver fibrosis is the main predictor of most types of chronic liver diseases. It is also a major cause of morbidity and mortality worldwide due to chronic viral hepatitis. [...]

Activation and accumulation of cardiac fibroblasts, which result in excessive extracellular matrix deposition and consequent mechanical stiffness, myocyte uncoupling, and ischemia, are key contributors to heart failure progression. Recently, endothelial-to-mesenchymal transition (EndoMT) and the recruitment of circulating hematopoietic progenitors to the heart have been reported to generate substantial numbers of cardiac fibroblasts in response to pressure overload-induced injury; therefore, these processes are widely considered to be promising therapeutic targets. Here, using multiple independent murine Cre lines and a collagenlal-GF-P fusion reporter, which specifically labels fibroblasts, we found that following pressure overload, fibroblasts were not derived from hematopoietic cells, EndoMT, or epicardial epithelial-to- mesenchymal transition. Instead, pressure overload promoted comparable proliferation and activation of two resident fibroblast lineages, including a previously described epicardial population and a population of endothelial origin. Together, these data present a paradigm for the origins of cardiac fibroblasts during development and in fibrosis. Furthermore, these data indicate that therapeutic strategies for reducing pathogenic cardiac fibroblasts should shift from targeting presumptive EndoMT or infiltrating hematopoietically derived fibroblasts, toward common pathways upregulated in two endogenous fibroblast populations., Introduction Heart failure is the primary cause of adult mortality in the developed world (1, 2). A key component of heart failure is excessive extracellular matrix deposition by cardiac fibroblasts [...]

Chemical or traumatic damage to the liver is frequently associated with aberrant healing (fibrosis) that overrides liver regeneration (1-5). The mechanism by which hepatic niche cells differentially modulate regeneration and fibrosis during liver repair remains to be defined (6-8). Hepatic vascular niche predominantly represented by liver sinusoidal endothelial cells deploys paracrine trophogens, known as angiocrine factors, to stimulate regeneration (9-15). Nevertheless, it is not known how pro-regenerative angiocrine signals from liver sinusoidal endothelial cells is subverted to promote fibrosis (16,17). Here, by combining an inducible endothelial-cell-specific mouse gene deletion strategy and complementary models of acute and chronic liver injury, we show that divergent angiocrine signals from liver sinusoidal endothelial cells stimulate regeneration after immediate injury and provoke fibrosis after chronic insult. The pro-fibrotic transition of vascular niche results from differential expression of stromal-derived factor-1 receptors, CXCR7 and CXCR4 (refs 18-21), in liver sinusoidal endothelial cells. After acute injury, CXCR7 upregulation in liver sinusoidal endothelial cells acts with CXCR4 to induce transcription factor Id1, deploying pro-regenerative angiocrine factors and triggering regeneration. Inducible deletion of Cxcr7 in sinusoidal endothelial cells ([Cxcr7.sup.iΔEC/iΔEC]) from the adult mouse liver impaired liver regeneration by diminishing Id1-mediated production of angiocrine factors (9-11). By contrast, after chronic injury inflicted by iterative hepatotoxin (carbon tetrachloride) injection and bile duct ligation, constitutive FGFR1 signalling in liver sinusoidal endothelial cells counterbalanced CXCR7-dependent pro-regenerative response and augmented CXCR4 expression. This predominance of CXCR4 over CXCR7 expression shifted angiocrine response of liver sinusoidal endothelial cells, stimulating proliferation of [desmin.sup.+] hepatic stellate-like cells (22,23) and enforcing a pro-fibrotic vascular niche. Endothelial-cell-specific ablation of either Fgfr1 ([Fgfr1.sup.iΔEC/iΔEC]) or Cxcr4 ([Cxcr7.sup.iΔEC/iΔEC]) in mice restored the pro-regenerative pathway and prevented FGFR1-mediated maladaptive subversion of angiocrine factors. Similarly, selective CXCR7 activation in liver sinusoidal endothelial cells abrogated fibrogenesis. Thus, we demonstrate that in response to liver injury, differential recruitment of proregenerative CXCR7-Id1 versus pro-fibrotic FGFR1 CXCR4 angiocrine pathways in vascular niche balances regeneration and fibrosis. These results provide a therapeutic roadmap to achieve hepatic regeneration without provoking fibrosis (1,2,4)., Despite the liver's capacity to undergo regeneration, chronic or overwhelming injury often causes liver fibrosis that culminates in cirrhosis and hepatic failure (1-7). The integrated process of liver repair includes [...]

Quercetin exhibits numerous pharmacological effects, including the capacity for cardioprotection. This study aimed to investigate whether quercetin or its glycoside derivative rutin has any protective action against isoproterenol (ISO) induced cardiac fibrosis, and investigate the structure-activity relationship. Male Wistar rats were injected subcutaneously with ISO (15 mg x [(kg body mass).sup.-1]) to induce experimental cardiac fibrosis. The cardioprotective effect of co-treatment with quercetin (25 or 50 mg x [kg.sup.-1]) or rutin (25 or 50 mg x [kg.sup.-1]) was investigated in ISO-induced cardiac fibrosis in rats. The administration of quercetin and rutin signifcantly decreased the cardiac weight index and myocardial enzyme activity, increased the activity of superoxide dismutase in the serum, and inhibited the ISO-induced increase in angiotensin II and aldosterone in the plasma. Furthermore, overexpression of transforming growth factor [β.sub.1] (TGF-[β.sub.1], connective tissue growth factor (CTGF), and excessive deposition of extracellular matrix (ECM) in isoproterenol-treated myocardial tissues were normalized by quercetin and rutin. Our results suggest that both quercetin and rutin exhibited cardioprotective effects in cardiac fibrosis induced by ISO in the rat heart. Moreover, the effects of rutin are weaker than quercetin at the same dose. The mechanism of these effects may be related to antioxidative stress, inhibition of the renin-angiotensin-aldosterone system, decrease in the expression of TGF-[β.sub.1] and CTGF, and the subsequent reduction in the deposition of the ECM. Key words: quercetin, rutin, cardiac fibrosis, TGF-β1, CTGF, ECM. La quercetine exerce de nombreux effets pharmacologiques, notamment une activite cardioprotectrice. Cette etude visait al determiner si la quercetine ou son derive glycoside, la rutine, exerce une quelconque activite protectrice envers la fibrose cardiaque induite par l'isoproterenol, et a comprendre la relation entre sa structure et son activite. Des rats Wistar males ont recu une injection sous-cutanee d'isoproterenol (15 mg x [(kg de masse corporelle).sup.-1]) afin d'induire une fibrose cardiaque experimentale. L'effet d'un traitement conjoint a la quercetine (25 ou 50 mg x [kg.sup.-1])oua la rutine (25 ou 50 mg x [kg.sup.-1]) sur la fibrose cardiaque induite par l'isoproterenol chez les rats a ete examine. L'administration de quercetine et de rutine diminuait significativement l'indice du poids cardiaque et l'activite des enzymes du myocarde, augmentait l'activite de la superoxyde dismutase serique et inhibait l'augmentation d'angiotensine II et d'aldosterone induite par l'isoproterenol dans le plasma. De plus, la surexpression de TGF-[β.sub.1] et de CTGF, de meme que le depot excessif de matrice extracellulaire (MEC) dans le tissu myocardique expose a l'isoproterenol etaient normalises par la quercetine et la rutine. Nos resultats suggerent que la quercetine et la rutine exercent des effets cardioprotecteurs dans la fibrose cardiaque induite par l'ISO dans le coeur des rats, et qu'en plus, les effets de la rutine sont plus faibles que ceux de la quercetine a la meme dose. Le mecanisme derriere ces effets peut etre relie au stress anti-oxydant, a l'inhibition du systeme renine-angiotensine-aldosterone, a la diminution de l'expression de TGF-[β.sub.1] et de TCGF, et subsequemment la reduction du depot de MEC. [Traduit par la Redaction] Mots-cles: quercetine, rutine, fibrose cardiaque, TGF-[β.sub.1], CTGF, matrice extracellulaire., Introduction Cardiac fibrosis is a major factor in the progression of myocardial infarction and heart failure. Prevention of cardiac fibrosis is a critical goal in the treatment of myocardial infarction [...]

Liver fibrosis is accompanied by hepatocyte death and proliferation of α- SMA+ fibrogenic cells (activated hepatic stellate cells and myofibroblasts), which synthesize extracellular matrix components that contribute to disorganization of the hepatic parenchyma and loss of liver function. Therefore, apoptosis of these fibrogenic cells is important to hepatic regeneration. This study aimed to analyze the effect of cell therapy using bone marrow mononuclear cell (BMMNC) transplantation on α-SMA expression and on apoptosis of hepatic cells during liver fibrosis induced by bile duct ligation (BDL). Livers were collected from normal rats, fibrotic rats after 14 and 21 days of BDL, and rats that received BMMNC at 14 days of BDL and were analyzed after 7 days. Apoptosis in fibrogenic cells was analyzed by immunoperoxidase, confocal microscopy, and Western blotting, and liver regeneration was assessed by proliferating cell nuclear antigen staining. Results showed that caspase-3 and proliferating cell nuclear antigen expression were significantly increased in the BMMNC-treated group. Additionally, confocal microscopy analysis showed cells coexpressing α-SMA and caspase-3 in these animals, suggesting fibrogenic cell death. These results suggest a novel role for BMMNC in liver regeneration during fibrotic disease by stimulating fibrogenic cells apoptosis and hepatocyte proliferation, probably through secretion of specific cytokines that modulate the hepatic microenvironment toward an antifibrogenic balance. Key words: liver fibrosis, bone marrow cells, hepatic stellate cells, myofibroblasts, apoptosis. La fibrose du foie s'accompagne de la mort des hepatocytes et de la proliferation de cellules fibrogenes α-SMA+ (cellules de Kupfer activees et myofibroblastes) qui synthetisent les composants de la matrice extracellulaire qui contribuent a la desorganisation du parenchyme hepatique et a la perte de fonction hepatique. Ainsi, l'apoptose de ces cellules fibrogenes est importante pour que la regeneration hepatique survienne. Cette etude visait a analyser l'effet d'une therapie cellulaire utilisant la transplantation de cellules mononucleees de la moelle osseuse (CMNMO) sur l'expression de α-SMA et sur l'apoptose des cellules hepatiques durant la fibrose hepatique induite par la ligature du canal biliaire (LCB). Les foies ont ete recueillis de rats normaux, de rats avec fibrose apres 14 et 21 jours de LCB et de rats ayant recu une transplantation de CMNMO 14 jours apres la LCB, et ils ont ete analyses apres 7 jours. L'apoptose des cellules fibrogenes a ete analysee par immunoperoxydase, microscopie confocale et buvardage western, et la regeneration de foie a ete evaluee par une coloration du PCNA. Les resultats ont montre que l'expression de la caspase-3 et du PCNA etait significativement accrue chez le groupe traite aux CMNMO. En outre, l'analyse en microscopie confocale a montre des cellules co-exprimant le α-SMA et la capsase-3 chez ces animaux, suggerant la mort des cellules fibrogenes. Ces resultats suggerent un role inedit des CMNMO dans la regeneration du foie lors de la fibrose hepatique en stimulant l'apoptose des cellules fibrogene et la proliferation des hepatocytes, probablement par l'intermediaire de la secretion de cytokines specifiques qui modulent le microenvironnement hepatique vers un equilibre anti-fibrogene. [Traduit par la Redaction] Mots-cles: fibrose du foie, cellules de la moelle osseuse, cellules de Kupfer, myofibroblastes, apoptose., Introduction Liver fibrosis is a pathogenic process that follows chronic liver injury and leads to extracellular matrix (ECM) accumulation and loss of the functional hepatic parenchyma. Its final stage, cirrhosis, [...]

The INK4a proteins [p16.sup.INK4a] and [p19.sup.ARF] regulate cell cycle arrest and senescence. However, the role of these proteins in controlling these processes in the normal kidney and following injury is unknown. We performed unilateral ureteral obstruction (UUO) to induce fibrosis in 2- to 3-mo-old wild-type (WT) C57/B6 and INK4a knockout mice. By quantitative RT-PCR, [p16.sup.INK4a] levels were increased sixfold in WT mice 7 days after UUO and [p19.sup.ARF] remained undetectable. Kidney sections were examined to determine levels and localization of [p16.sup.INK4a], apoptosis, fibrosis, and senescent cells. INK4a knockout mice displayed mesangial cell proliferation, increased matrix deposition, and myoflbroblast differentiation under normal conditions. Following UUO, INK4a knockout mice displayed 10-fold increased tubular and interstitial cell proliferation, 75% decreased collecting duct apoptosis, 2-fold greater collagen and fibronectin deposition, and no cell senescence by senescence-associated [beta]-galactosidase staining compared with WT mice. Both INK4a knockout mesangial cells and kidney lysates from knockout mice following injury showed elevated levels of IL-6 by ELISA compared with WT samples. INK4a knockout epithelial cell cultures displayed increased mesenchymal cell markers when exposed to transforming growth factor-[beta]. These results confirm that [p16.sup.INK4a] controls cell proliferation and matrix production and mitigates fibrosis following injury and suggest that the mechanism involves a role in limiting inflammation and cell proliferation. mesangial cell; UUO doi: 10.1152/ajprenal.00378.2010

Adipose tissue macrophages are associated with insulin resistance and are linked to changes in the extracellular matrix. To better characterize adipose macrophages, the extracellular matrix, and adipocyte-macrophage interactions, gene expression from adipose tissue and the stromal vascular fraction was assessed for markers of inflammation and fibrosis, and macrophages from obese and lean subjects were counted and characterized immunohistochemically. Coculture experiments examined the effects of adipocyte-macrophage interaction. Collagen VI gene expression was associated with insulin sensitivity and CD68 (r = -0.56 and 0.60, P < 0.0001) and with other markers of inflammation and fibrosis. Compared with adipose tissue from lean subjects, adipose tissue from obese subjects contained increased areas of fibrosis, which correlated inversely with insulin sensitivity (r = -0.58, P < 0.02) and positively with macrophage number (r = 0.70, P < 0.01). Although macrophages in crownlike structures (CLS) were more abundant in obese adipose tissue, the majority of macrophages were associated with fibrosis and were not organized in CLS. Macrophages in CLS were predominantly M1, but most other macrophages, particularly those in fibrotic areas, were M2 and also expressed CD150, a marker of M2c macrophages. Coculture of THP-1 macrophages with adipocytes promoted the M2 phenotype, with a lower level of IL-1 expression and a higher ratio of IL-10 to IL-12. Transforming growth factor-[beta] (TGF-[beta]) was more abundant in M2 macrophages and was further increased by coculture with adipocytes. Downstream effectors of TGF-[beta], such as plasminogen activator inhibitor-l, collagen VI, and phosphorylated Smad, were increased in macrophages and adipocytes. Thus adipose tissue of insulin-resistant humans demonstrated increased fibrosis, M2 macrophage abundance, and TGF-[beta] activity. alternatively activated macrophages; inflammation; crownlike structures doi: 10.1152/ajpendo.00329.2010.

Maternal obesity (MO) has harmful effects on both fetal development and subsequent offspring health. The impact of MO on fetal myocardium development has received little attention. Fibrogenesis is regulated by the transforming growth factor-[beta] (TGF-[beta])/p38 signaling pathway. Using the well-established model of MO in pregnant sheep, we evaluated the effect of MO on TGF-[beta]/p38 and collagen accumulation in fetal myocardium. Nonpregnant ewes were assigned to a control diet [Con, fed 100% of National Research Council (NRC) nutrient recommendations] or obesogenic diet (OB, fed 150% of NRC recommendations) from 60 days before conception. Fetal ventricular muscle was sampled at 75 and 135 days of gestation (dG). At 75 dG, the expression of precursor TGF-[beta] was 39.9 [+ or -] 9.9% higher (P < 0.05) in OB than Confetal myocardium, consistent with the higher content of phosphorylated Smad3 in OB myocardium. The phosphorylation of p38 tended to be higher in OB myocardium (P = 0.08). In addition, enhanced Smad complexes were bound to Smad-binding elements in 75 dG OB fetal myocardium measured by DNA mobility shift assay (130.2 [+ or -] 26.0% higher, P < 0.05). Similar elevation of TGF-[beta] signaling was observed in OB fetal myocardium at 135 dG. Total collagen concentration in OB was greater than Con fetal myocardium (2.42 [+ or -] 0.16 vs. 1.87 [+ or -] 0.04%, P < 0.05). Matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-3 were higher in the Con group compared with OB sheep (43.86 [+ or -] 16.01 and 37.23 [+ or -] 7.97% respectively, P < 0.05). In summary, MO results in greater fetal heart connective tissue accumulation associated with an upregulated TGF-[beta]/p38 signaling pathway at late gestation; such changes would be expected to negatively impact offspring heart function. collagen; fibrogenesis; transforming growth factor-[beta]; maternal obesity; fetus; myocardium doi: 10.1152/ajpendo.00434.2010.

Ethanol metabolism in the liver induces oxidative stress and altered cytokine production preceding myofibroblast activation and fibrogenic responses. The purpose of this study was to determine how ethanol affects the fibrogenic response in precision-cut liver slices (PCLS). PCLS were obtained from chow-fed male Wistar rats (200-300 g) and were cultured up to 96 h in medium, 25 mM ethanol, or 25 mM ethanol and 0.5 mM 4-methylpyrazole (4-MP), an inhibitor of ethanol metabolism. Slices from every time point (24, 48, 72, and 96 h) were examined for glntathione (GSH) levels, lipid peroxidation [thiobarbituric acid-reactive substance (TBARS) assay], cytokine production (ELISA and RT-PCR), and myofibroblast activation [immunoblotting and immunohistochemistry for smooth muscle actin (SMA) and collagen]. Treatment of PCLS with 25 mM ethanol induced significant oxidative stress within 24 h, including depletion of cellular GSH and increased lipid peroxidation compared with controls (P < 0.05). Ethanol treatment also elicited a significant and sustained increase in interleukin-6 (IL-6) production (P < 0.05). Importantly, ethanol treatment accelerates a fibrogenic response after 48 h, represented by significant increases in SMA and collagen 1[alpha](I) production (P < 0.05). These ethanol-induced effects were prevented by the addition of 4-MP. Ethanol metabolism induces oxidative stress (GSH depletion and increased lipid peroxidation) and sustained IL-6 expression in rat PCLS. These phenomena precede and coincide with myofibroblast activation, which occurs within 48 h of treatment. These results indicate the PCLS can be used as in vitro model for studying multicellular interactions during the early stages of ethanol-induced liver injury and fibrogenesis. smooth muscle actin; collagen; IL-6; oxidative stress doi: 10.1152/ajpgi.00287.2009.

Smad ubiquitination regulatory factor-2 (Smurf2) is an E3 ubiqutin ligase that plays a pivotal role in regulating TGF-[beta] signaling via selectively targeting key components of the Smad pathway for degradation. In this study, we have investigated the regulation of Smurf2 expression, its target specificity, and the functional implication of its induction in the fibrotic kidney. Immunohistochemical staining revealed that Smurf2 was upregulated specifically in renal tubules of kidney biopsies from patients with various nephropathies. In vitro, Smurf2 mRNA and protein were induced in human proximal tubular epithelial cells (HKC-8) upon TGF-[beta]1 stimulation. Ectopic expression of Smurf2 was sufficient to reduce the steady-state levels of Smad2, but not Smad1, Smad3, Smad4, and Smad7, in HKC-8 cells. Interestingly, Smurf2 was also able to downregulate the Smad transcriptional corepressors Ski, SnoN, and TG-interacting factor. Inhibition of the proteasomal pathway prevented Smurf2-mediated downregulation of Smad2 and Smad corepressors. Functionally, overexpression of Smurf2 enhanced the transcription of the TGF-[beta]-responsire promoter and augmented TGF-[beta]1-mediated E-cadherin suppression, as well as fibronectin and type I collagen induction in HKC-8 cells. These results indicate that Smurf2 specifically targets both positive and negative Smad regulators for destruction in tubular epithelial cells, thereby providing a complex fine-tuning of TGF-[beta] signaling. It appears that dysregulation of Smurf2 could contribute to an aberrant TGF-[beta]/Smad signaling in the pathogenesis of kidney fibrosis. SnoN; renal fibrosis; TGF-[beta]1; ubiquitination

The numerous nonmyocytes present within the myocardium may establish electrical connections with myocytes through gap junctions, formed naturally or as a result of a cell therapy. The strength of the coupling and its potential impact on action potential characteristics and conduction are not well understood. This study used computer simulation to investigate the load-induced electrophysiological consequences of the coupling of myocytes with fibroblasts, where the fibroblast resting potential, density, distribution, and coupling strength were varied. Conduction velocity (CV), upstroke velocity, and action potential duration (APD) were analyzed for longitudinal and transverse impulse propagation in a two-dimensional microstructure tissue model, developed to represent a monolayer culture of cardiac cells covered by a layer of fibroblasts. The results show that 1) at weak coupling (8 nS), all of the effects saturated; and 4) APD at 90% repolarization was usually prolonged by 0-20 ms (up to 60-80 ms for high fibroblast density and coupling) by the coupling to fibroblasts. The changes in APD depended on the fibroblast resting potential. This complex, coupling-dependent interaction of fibroblast and myocytes also has relevance to the integration of other nonmyocytes in the heart, such as those used in cellular therapies. computer modeling; electrophysiology; nonmyocytes; gap junctions; fibrosis

Tubulointerstitial fibrosis is a hallmark of chronic progressive kidney disease leading to end-stage renal failure. An endogenous product of heine oxygenase activity, carbon monoxide (CO), has been shown to exert cytoprotection against tissue injury. Here, we explored the effects of exogenous administration of low-dose CO in an in vivo model of renal fibrosis induced by unilateral ureteral obstruction (UUO) and examined whether CO can protect against kidney injury. UUO in mice leads to increased extracellular matrix (ECM) deposition and tubulointerstitial fibrosis within 4 to 7 days. Kidneys of mice exposed to low-dose CO, however, had markedly reduced ECM deposition after UUO. Moreover, low-dose CO treatment inhibited the induction of s-smooth muscle actin ([alpha]-SMA) and major ECM proteins, type 1 collagen and fibronectin, in kidneys after UUO. In contrast, these anti-fibrotic effects of CO treatment were abrogated in mice carrying null mutation of Mkk3, suggesting involvement of the MKK3 signaling pathway in mediating the CO effects. Additionally, in vitro CO exposure markedly inhibited TGF-[[beta].sub.1]-induced expression of [alpha]-SMA, collagen, and fibronectin in renal proximal tubular epithelial cells. Our findings suggest that low-dose CO exerts protective effects, via the MKK3 pathway, to inhibit development of renal fibrosis in obstructive nephropathy. transforming growth factor-[[beta].sub.1]; obstructive nephropathy; MAPK; MKK3; HO-1