Interleukin-1 beta Attenuates Myofibroblast Formation and Extracellular Matrix Production in Dermal and Lung Fibroblasts Exposed to Transforming Growth Factor-beta 1

One of the most potent pro-fibrotic cytokines is transforming growth factor (TGFβ). TGFβ is involved in the activation of fibroblasts into myofibroblasts, resulting in the hallmark of fibrosis: the pathological accumulation of collagen. Interleukin-1β (IL1β) can influence the severity of fibrosis, however much less is known about the direct effects on fibroblasts. Using lung and dermal fibroblasts, we have investigated the effects of IL1β, TGFβ1, and IL1β in combination with TGFβ1 on myofibroblast formation, collagen synthesis and collagen modification (including prolyl hydroxylase, lysyl hydroxylase and lysyl oxidase), and matrix metalloproteinases (MMPs). We found that IL1β alone has no obvious pro-fibrotic effect on fibroblasts. However, IL1β is able to inhibit the TGFβ1-induced myofibroblast formation as well as collagen synthesis. Glioma-associated oncogene homolog 1 (GLI1), the Hedgehog transcription factor that is involved in the transformation of fibroblasts into myofibroblasts is upregulated by TGFβ1. The addition of IL1β reduced the expression of GLI1 and thereby also indirectly inhibits myofibroblast formation. Other potentially anti-fibrotic effects of IL1β that were observed are the increased levels of MMP1, -2, -9 and -14 produced by fibroblasts exposed to TGFβ1/IL1β in comparison with fibroblasts exposed to TGFβ1 alone. In addition, IL1β decreased the TGFβ1-induced upregulation of lysyl oxidase, an enzyme involved in collagen cross-linking. Furthermore, we found that lung and dermal fibroblasts do not always behave identically towards IL1β. Suppression of COL1A1 by IL1β in the presence of TGFβ1 is more pronounced in lung fibroblasts compared to dermal fibroblasts, whereas a higher upregulation of MMP1 is seen in dermal fibroblasts. The role of IL1β in fibrosis should be reconsidered, and the differences in phenotypical properties of fibroblasts derived from different organs should be taken into account in future anti-fibrotic treatment regimes

YAP/TAZ deficiency reprograms macrophage phenotype and improves infarct healing and cardiac function after myocardial infarction

Adverse cardiac remodeling after myocardial infarction (MI) causes structural and functional changes in the heart leading to heart failure. The initial post-MI pro-inflammatory response followed by reparative or anti-inflammatory response is essential for minimizing the myocardial damage, healing, and scar formation. Bone marrow-derived macrophages (BMDMs) are recruited to the injured myocardium and are essential for cardiac repair as they can adopt both pro-inflammatory or reparative phenotypes to modulate inflammatory and reparative responses, respectively. Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are the key mediators of the Hippo signaling pathway and are essential for cardiac regeneration and repair. However, their functions in macrophage polarization and post-MI inflammation, remodeling, and healing are not well established. Here, we demonstrate that expression of YAP and TAZ is increased in macrophages undergoing pro-inflammatory or reparative phenotype changes. Genetic deletion of YAP/TAZ leads to impaired pro-inflammatory and enhanced reparative response. Consistently, YAP activation enhanced pro-inflammatory and impaired reparative response. We show that YAP/TAZ promote pro-inflammatory response by increasing interleukin 6 (IL6) expression and impede reparative response by decreasing Arginase-I (Arg1) expression through interaction with the histone deacetylase 3 (HDAC3)-nuclear receptor corepressor 1 (NCoR1) repressor complex. These changes in macrophages polarization due to YAP/TAZ deletion results in reduced fibrosis, hypertrophy, and increased angiogenesis, leading to improved cardiac function after MI. Also, YAP activation augmented MI-induced cardiac fibrosis and remodeling. In summary, we identify YAP/TAZ as important regulators of macrophage-mediated pro-inflammatory or reparative responses post-MI

New Insights into Hippo/YAP Signaling in Fibrotic Diseases

Fibrosis results from defective wound healing processes often seen after chronic injury and/or inflammation in a range of organs. Progressive fibrotic events may lead to permanent organ damage/failure. The hallmark of fibrosis is the excessive accumulation of extracellular matrix (ECM), mostly produced by pathological myofibroblasts and myofibroblast-like cells. The Hippo signaling pathway is an evolutionarily conserved kinase cascade, which has been described well for its crucial role in cell proliferation, apoptosis, cell fate decisions, and stem cell self-renewal during development, homeostasis, and tissue regeneration. Recent investigations in clinical and pre-clinical models has shown that the Hippo signaling pathway is linked to the pathophysiology of fibrotic diseases in many organs including the lung, heart, liver, kidney, and skin. In this review, we have summarized recent evidences related to the contribution of the Hippo signaling pathway in the development of organ fibrosis. A better understanding of this pathway will guide us to dissect the pathophysiology of fibrotic disorders and develop effective tissue repair therapies

Emerging roles of the Hippo signaling pathway in modulating immune response and inflammation-driven tissue repair and remodeling

10.1111/febs.16449FEBS JOURNA

New Insights into Hippo/YAP Signaling in Fibrotic Diseases

Fibrosis results from defective wound healing processes often seen after chronic injury and/or inflammation in a range of organs. Progressive fibrotic events may lead to permanent organ damage/failure. The hallmark of fibrosis is the excessive accumulation of extracellular matrix (ECM), mostly produced by pathological myofibroblasts and myofibroblast-like cells. The Hippo signaling pathway is an evolutionarily conserved kinase cascade, which has been described well for its crucial role in cell proliferation, apoptosis, cell fate decisions, and stem cell self-renewal during development, homeostasis, and tissue regeneration. Recent investigations in clinical and pre-clinical models has shown that the Hippo signaling pathway is linked to the pathophysiology of fibrotic diseases in many organs including the lung, heart, liver, kidney, and skin. In this review, we have summarized recent evidences related to the contribution of the Hippo signaling pathway in the development of organ fibrosis. A better understanding of this pathway will guide us to dissect the pathophysiology of fibrotic disorders and develop effective tissue repair therapies

The pro-fibrotic properties of transforming growth factor on human fibroblasts are counteracted by caffeic acid by inhibiting myofibroblast formation and collagen synthesis

Fibrosis is a chronic disorder affecting many organs. A universal process in fibrosis is the formation of myofibroblasts and the subsequent collagen deposition by these cells. Transforming growth factor beta1 (TGF beta 1) plays a major role in the formation of myofibroblasts, e.g. by activating fibroblasts. Currently, no treatments are available to circumvent fibrosis. Caffeic acid phenethyl ester (CAPE) shows a broad spectrum of biological activities, including anti-fibrotic properties in vivo in mice and rats. However, little is known about the direct effects of CAPE on fibroblasts. We have tested whether CAPE is able to suppress myofibroblast formation and collagen formation of human dermal and lung fibroblasts exposed to TGF beta 1, and found that this was indeed the case. In fact, the formation of myofibroblasts by TGF beta 1 and subsequent collagen formation was completely abolished by CAPE. The same was observed for fibronectin and tenascin C. The lack of myofibroblast formation is likely due to the suppression of GLI1 and GLI2 expression by CAPE because of diminished nuclear SMAD2/3 levels. Post-treatment with CAPE after myofibroblast formation even resulted in a partial reversal of myofibroblasts into fibroblasts and/or reduction in collagen formation. Major discrepancies were seen between mRNA levels of collagen type I and cells stained positive for collagen, underlining the need for protein data in fibrosis studies to make reliable conclusions

List of primers used for qRT-PCR analysis.

<p>List of primers used for qRT-PCR analysis.</p

Effects of IL1β and TGFβ1 on the expression of collagen type III in dermal and lung fibroblasts.

<p>(A–B) HDFa and HLFa were treated with IL1β, TGFβ1, or a combination of both, for 24 and 48 h. The mRNA levels of COL3A1 were measured with qRT-PCR and expressed as fold change compared to untreated control. (C–D) The mRNA level of COL3A1 in HDFa and HLFa. Fibroblasts were pre-treated with TGFβ1 for 48 h followed by IL1β for 48 h and quantified by qRT-PCR and expressed as fold change compared to untreated control.</p

Effects of IL1β on TGFβ1-induced gene expression of Hedgehog pathway effector GLI1 and its isoform GLI1ΔN in dermal and lung fibroblasts.

<p>(A–B) HDFa and HLFa were treated with IL1β, TGFβ, or a combination of both for 24 and 48 h. The mRNA levels of GLI1 were measured with qRT-PCR and expressed as fold change compared to untreated control. (C–D) The mRNA level of GLI1 in HDFa and HLFa. Fibroblasts were pre-treated with TGFβ1 for 48 h followed by IL1β for 48 h and quantified by qRT-PCR and expressed as fold change compared to untreated control. (E–F) HDFa and HLFa were treated with IL1β, TGFβ1, or a combination of both, for 24 and 48 h. The mRNA levels of GLI1ΔN were measured with qRT-PCR and expressed as fold change compared to untreated control. (G–H) The mRNA level of GLI1ΔN in HDFa and HLFa. Fibroblasts were pre-treated with TGFβ1 for 48 h followed by IL1β for 48 h and quantified by qRT-PCR and expressed as fold change compared to untreated control.</p

Effects of IL1β and TGFβ1 on the expression of the intracellular collagen-modifying enzymes prolyl hydroxylase (P4HA1, P4HB) and lysyl hydroxylase (PLOD1, PLOD2) in dermal and lung fibroblasts.

<p>(A–H) HDFa and HLFa were treated with IL1β, TGFβ1, or a combination of both, for 24 and 48 h. The mRNA levels of P4HA1, P4HB, PLOD1 and PLOD2 were measured with qRT-PCR and expressed as fold change compared to untreated control. (I–J) The mRNA levels of PLOD2 in HDFa and HLFa. Fibroblasts were pre-treated with TGFβ1 for 48 h followed by IL1β for 48 h and quantified by qRT-PCR and expressed as fold change compared to untreated control.</p