Mechanisms of spontaneous resolution of rat liver fibrosis. Hepatic stellate cell apoptosis and reduced hepatic expression of metalloproteinase inhibitors

Inflammation and fibrosis in chronic liver diseases including non-alcoholic fatty liver disease and hepatitis C

At present chronic liver disease (CLD), the third commonest cause of premature death in the United Kingdom is detected late, when interventions are ineffective, resulting in considerable morbidity and mortality. Injury to the liver, the largest solid organ in the body, leads to a cascade of inflammatory events. Chronic inflammation leads to the activation of hepatic stellate cells that undergo trans-differentiation to become myofibroblasts, the main extra-cellular matrix producing cells in the liver; over time increased extra-cellular matrix production results in the formation of liver fibrosis. Although fibrogenesis may be viewed as having evolved as a “wound healing” process that preserves tissue integrity, sustained chronic fibrosis can become pathogenic culminating in CLD, cirrhosis and its associated complications. As the reference standard for detecting liver fibrosis, liver biopsy, is invasive and has an associated morbidity, the diagnostic assessment of CLD by non-invasive testing is attractive. Accordingly, in this review the mechanisms by which liver inflammation and fibrosis develop in chronic liver diseases are explored to identify appropriate and meaningful diagnostic targets for clinical practice. Due to differing disease prevalence and treatment efficacy, disease specific diagnostic targets are required to optimally manage individual CLDs such as non-alcoholic fatty liver disease and chronic hepatitis C infection. To facilitate this, a review of the pathogenesis of both conditions is also conducted. Finally, the evidence for hepatic fibrosis regression and the mechanisms by which this occurs are discussed, including the current use of antifibrotic therapy.

Evasion of apoptosis by myofibroblasts: a hallmark of fibrotic diseases

Organ fibrosis is a lethal outcome of autoimmune rheumatic diseases such as systemic sclerosis. Myofibroblasts are scar-forming cells that are ultimately responsible for the excessive synthesis, deposition and remodelling of extracellular matrix proteins in fibrosis. Advances have been made in our understanding of the mechanisms that keep myofibroblasts in an activated state and control myofibroblast functions. However, the mechanisms that help myofibroblasts to persist in fibrotic tissues remain poorly understood. Myofibroblasts evade apoptosis by activating molecular mechanisms in response to pro-survival biomechanical and growth factor signals from the fibrotic microenvironment, which can ultimately lead to the acquisition of a senescent phenotype. Growing evidence suggests that myofibroblasts and senescent myofibroblasts, rather than being resistant to apoptosis, are actually primed for apoptosis owing to concomitant activation of cell death signalling pathways; these cells are poised to apoptose when survival pathways are inhibited. This knowledge of apoptotic priming has paved the way for new therapies that trigger apoptosis in myofibroblasts by blocking pro-survival mechanisms, target senescent myofibroblast for apoptosis or promote the reprogramming of myofibroblasts into scar-resolving cells. These novel strategies are not only poised to prevent progressive tissue scarring, but also have the potential to reverse established fibrosis and to regenerate chronically injured tissues.

Dual TBK1/IKKɛ inhibitor amlexanox attenuates the severity of hepatotoxin-induced liver fibrosis and biliary fibrosis in mice

Although numerous studies have suggested that canonical IκB kinases (IKK) play a key role in the progression of liver fibrosis, the role of non-canonical IKKε and TANK-binding kinase 1 (TBK1) on the development and progression of liver fibrosis remains unclear. To demonstrate such issue, repeated injection of CCl4 was used to induce hepatotoxin-mediated chronic liver injury and biliary fibrosis was induced by 0.1% diethoxycarbonyl-1, 4-dihydrocollidine diet feeding for 4 weeks. Mice were orally administered with amlexanox (25, 50, and 100 mg/kg) during experimental period. Significantly increased levels of TBK1 and IKKε were observed in fibrotic livers or hepatic stellate cells (HSCs) isolated from fibrotic livers. Interestingly, amlexanox treatment significantly inhibited the phosphorylation of TBK1 and IKKε accompanied by reduced liver injury as confirmed by histopathologic analysis, decreased serum biochemical levels and fibro-inflammatory responses. Additionally, treatment of amlexanox promoted the fibrosis resolution. In accordance with these findings, amlexanox treatment suppressed HSC activation and its related fibrogenic responses by partially inhibiting signal transducer and activator of transcription 3. Furthermore, amlexanox decreased the activation and inflammatory responses in Kupffer cells. Collectively, we found that inhibition of the TBK1 and IKKε by amlexanox is a promising therapeutic strategy to cure liver fibrosis.

Quinolizidine alkaloids derivatives from Sophora alopecuroides Linn: Bioactivities, structure-activity relationships and preliminary molecular mechanisms

Quinolizidine alkaloids, as essential active ingredients extracted from Sophora alopecuroides Linn, have been well concerned in the past several decades owing to the unique structural features and numerous pharmacological activities. Quinolizidine alkaloids consist of matrine, oxymatrine, sophoridine, sophocarpine and aloperine etc. Additionally, quinolizidine alkaloids exert various excellent activities, including anti-cancer, anti-inflammation, anti-fibrosis, anti-virus and anti-arrhythmia regulations. In this review, we comprehensively clarify the pharmacological activities of quinolizidine alkaloids, as well as the relationship between biological function and structure-activity of substituted quinolizidine alkaloids. We believe that biological agents based on the pharmacological functions of quinolizidine alkaloids could be well applied in clinical practice.

Soluble Thy-1 reverses lung fibrosis via its integrin-binding motif

Loss of Thy-1 expression in fibroblasts correlates with lung fibrogenesis; however, the clinical relevance of therapeutic targeting of myofibroblasts via Thy-1-associated pathways remains to be explored. Using single (self-resolving) or repetitive (nonresolving) intratracheal administration of bleomycin in type 1 collagen-GFP reporter mice, we report that Thy-1 surface expression, but not mRNA, is reversibly diminished in activated fibroblasts and myofibroblasts in self-resolving fibrosis. However, Thy-1 mRNA expression is silenced in lung with nonresolving fibrosis following repetitive bleomycin administration, associated with persistent activation of αv integrin. Thy1-null mice showed progressive αv integrin activation and myofibroblast accumulation after a single dose of bleomycin. In vitro, targeting of αv integrin by soluble Thy-1-Fc (sThy-1), but not RLE-mutated Thy-1 or IgG, reversed TGF-β1-induced myofibroblast differentiation in a dose-dependent manner, suggesting that Thy-1's integrin-binding RGD motif is required for the reversibility of myofibroblast differentiation. In vivo, treatment of established fibrosis induced either by single-dose bleomycin in WT mice or by induction of active TGF-β1 by doxycycline in Cc10-rtTA-tTS-Tgfb1 mice with sThy-1 (1000 ng/kg, i.v.) promoted resolution of fibrosis. Collectively, these findings demonstrate that sThy-1 therapeutically inhibits the αv integrin-driven feedback loop that amplifies and sustains fibrosis.

Ursolic Acid Improves Intestinal Damage and Bacterial Dysbiosis in Liver Fibrosis Mice

Liver fibrosis is a reversible process of extracellular matrix deposition or scar formation after liver injury. Intestinal damage and bacterial dysbiosis are important concomitant intestinal changes in liver fibrosis and may in turn accelerate the progression of liver fibrosis through the gut-liver axis. RhoA, an important factor in the regulation of the cytoskeleton, plays an important role in intestinal damage. We investigated the effects of ursolic acid (UA), a traditional Chinese medicine with anti-fibrotic effects, on intestinal damage and bacterial disorder through the RhoA pathway. UA treatment reduced intestinal damage by inhibiting the inflammatory factor TNF-α and increasing the expression of tight junction proteins and antibacterial peptides to protect the intestinal barrier. Moreover, the corrective effect of UA on bacterial dysbiosis was also confirmed by sequencing of the 16S rRNA gene. Potential beneficial bacteria, such as the phylum Firmicutes and the genera Lactobacillus and Bifidobacterium, were increased in the UA group compared to the CCl₄ group. In liver fibrosis mice with RhoA inhibition via injection of adeno-associated virus, the liver fibrosis, intestinal damage, and flora disturbances were improved. Moreover, UA inhibited the expression of RhoA pathway components. In conclusion, UA improves intestinal damage and bacterial dysbiosis partly via the RhoA pathway. This may be a potential mechanism by which UA exerts its anti-fibrotic effects and provides effective theoretical support for the future use of UA in clinical practice.

Embryonic mesothelial-derived hepatic lineage of quiescent and heterogenous scar-orchestrating cells defined but suppressed by WT1

Activated hepatic stellate cells (aHSCs) orchestrate scarring during liver injury, with putative quiescent precursor mesodermal derivation. Here we use lineage-tracing from development, through adult homoeostasis, to fibrosis, to define morphologically and transcriptionally discreet subpopulations of aHSCs by expression of WT1, a transcription factor controlling morphological transitions in organogenesis and adult homoeostasis. Two distinct populations of aHSCs express WT1 after injury, and both re-engage a transcriptional signature reflecting embryonic mesothelial origin of their discreet quiescent adult precursor. WT1-deletion enhances fibrogenesis after injury, through upregulated Wnt-signalling and modulation of genes central to matrix persistence in aHSCs, and augmentation of myofibroblastic transition. The mesothelial-derived lineage demonstrates punctuated phenotypic plasticity through bidirectional mesothelial-mesenchymal transitions. Our findings demonstrate functional heterogeneity of adult scar-orchestrating cells that can be whole-life traced back through specific quiescent adult precursors to differential origin in development, and define WT1 as a paradoxical regulator of aHSCs induced by injury but suppressing scarring.

Naringenin attenuates the progression of liver fibrosis via inactivation of hepatic stellate cells and profibrogenic pathways

There is no effective treatment for hepatic fibrosis. Previously, we demonstrated that naringenin possesses the ability to prevent experimental chronic liver damage. Therefore, the objective of this work was to investigate whether naringenin could reverse carbon tetrachloride (CCl₄)-induced fibrosis in rats and, if so, to search for the mechanisms involved. CCl₄ was given to male Wistar rats (400 mg/kg, three times per week, i. p.) for 12 weeks; naringenin (100 mg/kg twice per day, p. o.) was administered from weeks 9-12 of the CCl₄ treatment. Liver damage and oxidative stress markers were measured. Masson's trichrome, hematoxylin-eosin staining and immunohistochemistry were performed. Zymography assays for MMP-9 and MMP-2 were carried out. TGF-β, CTGF, Col-I, MMP-13, NF-κB, IL-1β, IL-10, Smad7, pSmad3 and pJNK protein levels were determined by western blotting. In addition, α-SMA and Smad3 protein and mRNA levels were studied. Naringenin reversed liver damage, biochemical and oxidative stress marker elevation, and fibrosis and restored normal MMP-9 and MMP-2 activity. The flavonoid also preserved NF-κB, IL-1β, IL-10, TGF-β, CTGF, Col-I, MMP-13 and Smad7 protein levels. Moreover, naringenin decreased JNK activation and Smad3 phosphorylation in the linker region. Finally, α-SMA and Smad3 protein and mRNA levels were reduced by naringenin administration. The results of this study demonstrate that naringenin blocks oxidative stress, inflammation and the TGF-β-Smad3 and JNK-Smad3 pathways, thereby carrying out its antifibrotic effects and making it a good candidate to treat human fibrosis, as previously demonstrated in toxicological and clinical studies.

Hesperetin derivative attenuates CCl4-induced hepatic fibrosis and inflammation by Gli-1-dependent mechanisms

Hepatic fibrosis, a common pathological feature and leading cause of various chronic liver diseases, still lacks effective therapy. Hesperetin derivative (HD) is a derivative of Traditional Chinese Medicine monomer isolated from the fruit peel of Citrusaurantium L. (Rutaceae). In the present study, we revealed the anti-fibrotic effects of HD in CCl₄-induced mouse hepatic fibrosis model and in TGF-β1-activated LX-2 cells, in vivo and in vitro. Results showed that HD prevented CCl₄-induced liver injury and histological damage. Consistently, HD inhibited the up-regulation of liver fibrogenesis markers α-SMA, Col1α1, Col3α1 and TIMP-1 in primary hepatic stellate cells (HSCs) and suppressed inflammatory responses in primary liver macrophages from hepatic fibrosis mice. Furthermore, HD promoted the apoptosis of activated HSCs, a key step in the onset of fibrosis regression. Mechanistically, the Hedgehog pathway was involved in HD-treated hepatic fibrosis, and HD specifically contributed to attenuate the aberrant expression of Glioma associated oncogene-1 (Gli-1). Interestingly, blockade of Gli-1 removed the inhibitory effect of HD on activated HSCs, indicating that Gli-1 may play a pivotal role in mediating the anti-fibrotic effect of HD in hepatic fibrosis. Collectively, our results suggest that HD may be a potential anti-fibrotic Traditional Chinese Medicine monomer for the treatment of hepatic fibrosis.

Cannabinoid receptor-1 antagonism: a new perspective on treating a murine schistosomal liver fibrosis model

BACKGROUND

Formation of schistosomal granulomata surrounding the ova can result in schistosomiasis-associated liver fibrosis (SSLF). The current standard of treatment is praziquantel (PZQ), which cannot effectively reverse SSLF. The role of the cannabinoid (CB) receptor family in liver fibrosis has recently been highlighted.

OBJECTIVES

This study aimed to assess the therapeutic effect of CB1 receptor antagonism in reversing SSLF in a murine model of Schistosoma mansoni infection.

METHODS

One hundred male Swiss albino mice were divided equally into five groups: healthy uninfected control (group I), infected control (group II), PZQ treated (group III), rimonabant (RIM) (SR141716, a CB1 receptor antagonist)-treated (group IV) and group V was treated with combined PZQ and RIM. Liver sections were obtained for histopathological examination, alpha-1 smooth muscle actin (α-SMA) immunostaining and assessment of CB1 receptor expression using real-time polymerase chain reaction (RT-PCR).

FINDINGS

The most effective reduction in fibrotic marker levels and granuloma load was achieved by combined treatment with PZQ+RIM (group V): CB1 receptor expression (H = 26.612, p < 0.001), number of α-SMA-positive cells (F = 57.086, p < 0.001), % hepatic portal fibrosis (F = 42.849, p < 0.001) and number of granulomata (F = 69.088, p < 0.001).

MAIN CONCLUSIONS

Combining PZQ with CB1 receptor antagonists yielded the best results in reversing SSLF. To our knowledge, this is the first study to test this regimen in S. mansoni infection.

Diffusion-weighted imaging and variable flip angle T1 mapping: a supplement for image-guided biopsy in follow-up analysis of liver fibrosis

Purpose To evaluate the performance of diffusion-weighted imaging (DWI) and variable flip angle (VFA) T1 mapping as a supplement to image-guided biopsy in follow-up analysis of liver fibrosis. Materials and Methods This prospective study was approved by the institution's committee on human research, and written informed consent was provided from the enrolled patients. We investigated five MRI parameters of DWI and VFA T1 mapping, collected from 11 patients who underwent serial ultrasound image-guided biopsy with follow-up MRI within 1.5 years after treatment for liver fibrosis/cirrhosis. For each patient, four consecutive MRI examinations were conducted, including baseline MRI before treatment and three follow-up MRI examinations after treatment at each 0.5-year interval. ADC values at four b values and T1 relaxation times were correlated to pathology-confirmed liver fibrosis stages, which were subsequently divided into two groups, stages F2-3 and F4. The receiver operating characteristic (ROC) analysis and repeated measurement analysis of variance were used for statistical analysis. Results Among these ADC parameters, ADC value (b = 500 s/mm²) was the most consistent in differentiating between stage F2-3 and F4 liver fibrosis. Repeated measurement analysis showed that the intra-group and inter-group differences were 0.447 and 0.024, respectively. T1 relaxation time could not consistently differentiate between the F2-3 and F4 groups; however, it was repeatable, and the intra-group and inter-group differences were 0.410 and 0.042, respectively. Conclusion MRI-ADC value at a b value of 500 s/mm² can be a promising biomarker for differentiating stages F2-3 and F4 liver fibrosis. A combination of this biomarker with repeatable T1 relaxation time may function as a non-invasive tool for follow-up liver fibrosis in patients who reject repeated image-guided biopsy.

Modulatory effect of Prosopis juliflora leaves on hepatic fibrogenic and fibrolytic alterations induced in rats by thioacetamide

This study investigated the antifibrotic effect of Prosopis juliflora leaves crude methanolic extract (PJEL) against thioacetamide (TAA)-induced liver fibrosis. The phytochemical analysis of PJEL was performed via HPLC/MS in association with evaluating its free radical scavenging and cytotoxic activities. The antifibrotic activity of PJEL was assessed by dividing Wistar rats into 8 groups: normal control, PJEL1-administered rats (2 mg/ Kg b.w.), PJEL2-administered rats (4 mg/ Kg b.w.), PJEL3-administered rats (8 mg/Kg b.w.), TAA-induced hepatic fibrosis, TTA + PJEL1, TAA + PJEL2, and TAA + PJEL3. Results indicated that PJEL crude methanolic extract is rich in polyphenolic compounds and alkaloids. PJEL exerted free radical scavenging activity with IC₅₀ of 123.5 μg/mL and cytotoxic activity against a well-differentiated hepatocellular cell line (IC₅₀ = 11.1 μg/mL). PJEL at a dose of 4 mg/Kg b.w. ameliorated serum ALT activity and improved serum albumin level and hepatic hydroxyproline content in association with a reduction in the fibrosis stage. PJEL elevated hepatic tumor necrosis factor-α and interleukin-6 contents with less necrosis grade. PJEL post-therapy ameliorated the relative expression of Bcl-2, Col1A1, Mmp-9, and Mmp-2 genes in liver. CONCLUSION: PJEL possesses a good therapeutic activity against TAA-induced liver fibrosis via enhancing extracellular matrix removal and stimulating hepatic regeneration to decrease hepatic necrosis.

The Role of Myeloid-Derived Cells in the Progression of Liver Disease

Control of homeostasis and rapid response to tissue damage in the liver is orchestrated by crosstalk between resident and infiltrating inflammatory cells. A crucial role for myeloid cells during hepatic injury and repair has emerged where resident Kupffer cells, circulating monocytes, macrophages, dendritic cells and neutrophils control local tissue inflammation and regenerative function to maintain tissue architecture. Studies in humans and rodents have revealed a heterogeneous population of myeloid cells that respond to the local environment by either promoting regeneration or driving the inflammatory processes that can lead to hepatitis, fibrogenesis, and the development of cirrhosis and malignancy. Such plasticity of myeloid cell responses presents unique challenges for therapeutic intervention strategies and a greater understanding of the underlying mechanisms is needed. Here we review the role of myeloid cells in the establishment and progression of liver disease and highlight key pathways that have become the focus for current and future therapeutic strategies.

Gexia-Zhuyu Decoction Attenuates Carbon Tetrachloride-Induced Liver Fibrosis in Mice Partly via Liver Angiogenesis Mediated by Myeloid Cells

Background

This study aims to demonstrate the underlying correlation between the resolution of liver fibrosis induced by Gexia-Zhuyu decoction (GZD) treatment and myeloid cell-mediated angiogenesis.

Material/Methods

A liver fibrosis mouse model induced by carbon tetrachloride (CCl₄) intervention was employed in this study. Dynamics of blood liver function parameters were followed. The liver pathology was detected by Sirius Red and Masson staining. Matrix metalloproteinase (MMP) 2/9, tissue inhibitors of metalloproteinase (TIMP)-1/2, and vascular endothelial growth factor (VEGF)-A expression levels were measured. Bone marrow chimera mice were generated by transfer of bone morrow cells from green fluorescent protein (GFP)-knockin mice into irradiated wild-type mice, and were used it to visualize the role of myeloid cells on the fibrosis resolution induced by GZD treatment.

Results

The result of Sirius Red and Masson staining and the dynamics of blood liver function parameters showed that 5 weeks of GZD treatment attenuated the severity of liver fibrosis with continual CCl₄ administration. GZD treatment promoted the expression of MMP2/9 and repressed the heightened level of TIMP-1/2 in the recovery phase. More notably, the increased VEGF-A and augmented endothelial progenitor cells were observed in the liver and blood in mice that received GZD, and contributed to the remodeling of hepatic vascular though the CXCL12/CXCR4 axis. Then, chimera mice with GFP-positive bone marrow cells were used to show angiogenesis driven by GZD-induced myeloid cell motivation. We found that GZD facilitated myeloid cells binding to the vascular CXCR4 and induced the resolution of fibrosis.

Conclusions

This study shows that activation of myeloid cells induced by GZD administration accelerates the functional angiogenesis, which benefits the resolution of CCl₄-induced liver fibrosis.

Mechanisms for the Resolution of Organ Fibrosis

Fibrosis is a dynamic process with the potential for reversibility and restoration of near-normal tissue architecture and organ function. Herein, we review mechanisms for resolution of organ fibrosis, in particular that involving the lung, with an emphasis on the critical roles of myofibroblast apoptosis and clearance of deposited matrix.

The Effect of Splenectomy on the Reversal of Cirrhosis: a Prospective Study

Background

Studies have demonstrated that liver fibrosis can be reversed by medication treatments. After splenectomy, cirrhosis patients have short-term changes in several serum markers for cirrhosis and liver stiffness.

Aims

To investigate the effect of splenectomy on the severity of cirrhosis.

Methods

A total of 62 patients with cirrhosis and portal hypertension receiving splenectomy from December 2014 to July 2017 were enrolled. The degree of cirrhosis was preoperatively and postoperatively evaluated by serum markers, including hyaluronan (HA), laminin, amino-terminal propeptide of type III procollagen (PIIINP), type IV collagen (C-IV), liver stiffness (FibroScan), and liver volume.

Results

HA levels significantly increased at 1 week and 1 month postoperation (both P < 0.05), whereas the levels of PIIINP and C-IV significantly decreased from 1 month to 12 months postoperation (all P < 0.05). In addition, elastography examination demonstrated that the FibroScan score significantly reduced from 1 month to 24 months postoperation as compared with the baseline level (all P < 0.05). CT scan showed that the liver volume significantly increased at 6 months postoperation (P < 0.05). Furthermore, the alteration trends of these serum markers and the FibroScan score were further confirmed by the multivariate linear regression.

Conclusions

These observations suggested that splenectomy may result in long-term reversal of cirrhosis.

Effects of apoptosis on liver aging

As an irreversible and perennial process, aging is accompanied by functional and morphological declines in organs. Generally, aging liver exhibits a decline in volume and hepatic blood flow. Even with a preeminent regenerative capacity to restore its functions after liver cell loss, its biosynthesis and metabolism abilities decline, and these are difficult to restore to previous standards. Apoptosis is a programmed death process via intrinsic and extrinsic pathways, in which Bcl-2 family proteins and apoptosis-related genes, such as p21 and p53, are involved. Apoptosis inflicts both favorable and adverse influences on liver aging. Apoptosis eliminates transformed abnormal cells but promotes age-related liver diseases, such as nonalcoholic fatty liver disease, liver fibrosis, cirrhosis, and liver cancer. We summarize the roles of apoptosis in liver aging and age-related liver diseases.

Extracts from Fermented Black Garlic Exhibit a Hepatoprotective Effect on Acute Hepatic Injury

The mechanism of hepatoprotective compounds is usually related to its antioxidant or anti-inflammatory effects. Black garlic is produced from garlic by heat treatment and its anti-inflammatory activity has been previously reported. Therefore, the aim of this study was to investigate the hepatoprotective effect of five different extracts of black garlic against carbon tetrachloride (CCl₄)-induced acute hepatic injury (AHI). In this study, mice in the control, CCl₄, silymarin, and black garlic groups were orally administered distilled water, silymarin, and different fraction extracts of black garlic, respectively, after CCl₄ was injected intraperitoneally to induce AHI. The results revealed that the n-butanol layer extract (BA) and water layer extract (WS) demonstrated a hepatoprotective effect by reducing the levels of alanine aminotransferase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), and hepatic malondialdehyde (MDA). Furthermore, the BA and WS fractions of black garlic extract increased the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione reductase (GSH-Rd), tumor necrosis factor alpha (TNF-α), and the interleukin-1 (IL-1β) level in liver. It was concluded that black garlic exhibited significant protective effects on CCl₄-induced acute hepatic injury.

MicroRNA29a Reverts the Activated Hepatic Stellate Cells in the Regression of Hepatic Fibrosis through Regulation of ATPase H⁺ Transporting V1 Subunit C1

Activated hepatic stellate cells (aHSCs) play a key role in liver fibrosis. During the regression of fibrosis, aHSCs are transformed into inactivated cells (iHSCs), which are quiescent lipid-containing cells and express higher levels of lipid-related genes, such as peroxisome proliferators-activated receptors gamma (PPARγ). Here, we investigated the role of MicroRNA29a (Mir29a) in the resolution of liver fibrosis. Mir29a and lipid-related genes were up-regulated after the recovery of CCl₄-induced liver fibrosis in mice. PPARγ agonist rosiglitazone (RSG) promoted de-differentiation of aHSCs to iHSCs and up-regulated MIR29a expression in a human HSC cell line LX-2. MIR29a mimics in vitro promoted the expression of lipid-related genes, while decreased the expression of fibrosis-related genes. MIR29a inhibitor showed the reverse effects. ATPase H⁺ transporting V1 subunit C1 (Atp6v1c1) was increased in liver fibrosis, while down-regulated after the recovery in mice, and negatively regulated by MIR29a in LX-2 cells. Knockdown of ATP6V1C1 by siRNA decreased alpha-smooth muscle actin (α-SMA) and increased lipid-related genes expression. Simultaneous addition of MIR29a mimics and ATP6V1C1 siRNA further increased RSG promoted expression of lipid-related proteins in vitro. Collectively, MIR29a plays an important role during the trans-differentiation of aHSCs in the resolution of liver fibrosis, in part, through regulation of ATP6V1C1.

Regulation of CCl4-induced liver cirrhosis by hepatically differentiated human dental pulp stem cells

Liver transplantation is the most effective treatment for treating liver cirrhosis. However, a limited number of donors, graft rejection, and other complications can undermine transplant success. It is considered that cell transplantation is an alternative approach of liver transplantation. We previously developed a protocol for hepatic differentiation of cluster of differentiation 117+ stem cells isolated from human exfoliated deciduous tooth pulp (SHEDs) under hydrogen sulfide exposure. These cells showed excellent hepatic function. Here, we investigated whether hepatocyte-like cell transplantation is effective for treating carbon tetrachloride (CCl₄)-induced liver cirrhosis. SHEDs were hepatically differentiated, which was confirmed via immunological analyses and albumin concentration determination in the medium. Rats were intraperitoneally injected with CCl₄ for and the differentiated cells were injected into rat spleen. Histopathological and immunohistochemical analyses were performed. Liver functions were serologically and pathologically determined. Quantitative real-time-polymerase chain reaction was implemented to clarify the treatment procedure of liver cirrhosis. In vitro-differentiated hepatocyte-like cells were positive for all examined hepatic markers. SHED-derived hepatocyte transplantation eliminated liver fibrosis and restored liver structure in rats. Liver immunohistochemical analyses showed the presence of human-specific hepatic markers, i.e., a large amount of human hepatic cells were very active in the liver and spleen. Serological tests revealed significant liver function recovery in the transplantation group. Expression of genes promoting fibrosis increased after cirrhosis induction but was suppressed after transplantation. Our results suggest that xenotransplantation of hepatocyte-like cells of human origin can treat cirrhosis. Moreover, cell-based therapy of chronic liver conditions may be an effective option.

Transforming growth factor β (TGFβ) cross-talk with the unfolded protein response is critical for hepatic stellate cell activation

Transforming growth factor β (TGFβ) potently activates hepatic stellate cells (HSCs), which promotes production and secretion of extracellular matrix (ECM) proteins and hepatic fibrogenesis. Increased ECM synthesis and secretion in response to TGFβ is associated with endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). TGFβ and UPR signaling pathways are tightly intertwined during HSC activation, but the regulatory mechanism that connects these two pathways is poorly understood. Here, we found that TGFβ treatment of immortalized HSCs (i.e. LX-2 cells) induces phosphorylation of the UPR sensor inositol-requiring enzyme 1α (IRE1α) in a SMAD2/3-procollagen I-dependent manner. We further show that IRE1α mediates HSC activation downstream of TGFβ and that its role depends on activation of a signaling cascade involving apoptosis signaling kinase 1 (ASK1) and c-Jun N-terminal kinase (JNK). ASK1-JNK signaling promoted phosphorylation of the UPR-associated transcription factor CCAAT/enhancer binding protein β (C/EBPβ), which is crucial for TGFβ- or IRE1α-mediated LX-2 activation. Pharmacological inhibition of C/EBPβ expression with the antiviral drug adefovir dipivoxil attenuated TGFβ-mediated activation of LX-2 or primary rat HSCs in vitro and hepatic fibrogenesis in vivo Finally, we identified a critical relationship between C/EBPβ and the transcriptional regulator p300 during HSC activation. p300 knockdown disrupted TGFβ- or UPR-induced HSC activation, and pharmacological inhibition of the C/EBPβ-p300 complex decreased TGFβ-induced HSC activation. These results indicate that TGFβ-induced IRE1α signaling is critical for HSC activation through a C/EBPβ-p300-dependent mechanism and suggest C/EBPβ as a druggable target for managing fibrosis.

Functional heterogeneity of resident fibroblasts in the kidney

Chronic kidney disease (CKD) is a global public health problem, affecting over 10% of the world's population and more than half of the population aged over 70 years, imposing major costs on healthcare systems. Although the primary causes of CKD include various diseases such as diabetes, glomerulonephritis, and acute kidney injury (AKI), the progression of CKD is mediated by a common pathological pathway, which is mainly characterized by fibrosis and chronic inflammation. In this process, resident fibroblasts in the kidney play crucial roles. Accumulating evidence highlights the existence of functional heterogeneity and plasticity of fibroblasts and their diverse roles in kidney disease progression and resolution. In addition to renal fibrosis, renal anemia and peritubular capillary loss, two major complications of progressive CKD, are also caused by dysfunction of resident fibroblasts. Furthermore, age-dependent alterations in fibroblast behavior also contribute to age-dependent unique pathological conditions. In this article, we describe the current understanding regarding the behaviors of fibroblasts in the kidney in health, disease, and aging.

Artesunate may inhibit liver fibrosis via the FAK/Akt/β-catenin pathway in LX-2 cells

BACKGROUND

An increasing number of studies are investigating the effects of Chinese medicine on hepatic fibrosis, but only few studies have examined the anti-fibrogenic properties of Artesunate (ART). The aim of the present study was to explore the anti-fibrotic effects of ART on LX-2 cells, the human HSC cell line, and to determine potential molecular mechanisms via the focal adhesion kinase (FAK)/ protein kinase B (Akt)/ β-catenin pathway.

METHODS

LX-2 cells were stimulated with different concentration of ART (0, 12.5, 25 and 50 μg/ml) for 12, 24, 48 or 72 h, their proliferation was analyzed using the Cell Counting Kit-8 (CCK-8) assay. LX-2 cells were treated with different doses of ART (0, 12.5, 25 and 50 μg/ml) for 24 h, their apoptosis was measured using flow cytometry, the levels of mRNAs encoding collagen I or α-smooth muscle actin (α-SMA) were determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and the levels of key proteins in the FAK/Akt/β-catenin signaling pathway were assessed by western blotting. Specific inhibitors of FAK were added to the LX-2 cells cultures to explore the potential signaling.

RESULTS

Exposing LX-2 cells to ART efficiently inhibited their proliferation, significantly promoted early apoptosis in a dose-dependent manner, and markedly downregulated the mRNA expression of α-SMA and collagen I. In addition, ART, similar to FAK inhibitor PF562271 significantly inhibited the FAK/Akt/β-catenin signaling pathway by reducing the levels of phosphorylated FAK, Akt and GSK-3β.

CONCLUSIONS

Our present study shows that ART could regulate the proliferation, apoptosis and activation of LX-2. Meanwhile, the anti-fibrogenic mechanisms of ART was correlated with FAK/Akt/β-catenin pathway. Future research should verify and extend these findings, as well as explore other molecules and therefore serve as useful therapeutic targets.

Anti-fibrotic impact of Carvedilol in a CCl-4 model of liver fibrosis via serum microRNA-200a/SMAD7 enhancement to bridle TGF-β1/EMT track

Circulating microRNAs (miRNAs) play a role in modulating the prevalence of fibrosis and have been a target of the cardiac anti-fibrotic effect of Carvedilol. However, the impact of miRNAs on the hepatoprotective effect of this non-selective β-blocker has not been yet elucidated. Hence, the current goal is to evaluate the potential role of circulating miR-200a in the hepatic anti-fibrotic pathway of Carvedilol. Male Wistar rats were randomized into normal, CCl₄ (2 ml/kg, i.p, twice weekly for 8 weeks), and CCl₄ + Carvedilol (10 mg/kg, p.o, daily). Carvedilol over-expressed the circulating miR-200a to modulate epithelial mesenchymal transition (EMT) markers (vimentin, E-Cadherin). In turn, Carvedilol increased SMAD7 gene expression and protein content to attenuate the pro-fibrogenic marker transforming growth factor β1 (TGF-β1) and the inflammatory markers (p-38 MAPK and p-S536-NF-κB p65). The anti-fibrotic potential was reflected on the decreased expression of the mesenchymal product and EMT marker α-SMA, besides the improved histopathological examination, and the fibrosis scores/collagen quantification to enhance liver functions (AST, ALT, ALP, and AST/platelet ratio index; APRI). In conclusion, circulating miR-200a/SMAD7/TGF-β1/EMT/MAPK axis is crucial in the hepatic anti-fibrotic mechanism of Carvedilol.

Loss of Prolyl-Hydroxylase 1 Protects against Biliary Fibrosis via Attenuated Activation of Hepatic Stellate Cells

Liver fibrosis, eventually progressing to cirrhosis necessitating liver transplantation, poses a significant clinical problem. Oxygen shortage (hypoxia) and hypoxia-inducible transcription factors (HIFs) have been acknowledged as important drivers of liver fibrosis. The significance of oxygen-sensing HIF prolyl-hydroxylase (PHD) enzymes in this context has, however, remained elusive. In this study, we demonstrate that loss of PHD1 (PHD1^-/-) attenuates the development of liver fibrosis in mice subjected to chronic bile duct injury, induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine. This effect was accompanied with reduced recruitment of inflammatory leukocytes and attenuated occurrence of profibrotic myofibroblasts in PHD1^-/- livers. Further analyses focused on the significance of PHD1 in the activation of hepatic stellate cells (HSCs), which represent the driving force in liver fibrosis. Primary HSCs isolated from PHD1^-/- mice displayed significantly attenuated myofibroblast differentiation and profibrogenic properties compared with HSCs isolated from wild-type mice. Consistently, the expression of various profibrogenic and promitogenic factors was reduced in PHD1^-/- HSCs, without alterations in HIF-1α protein levels. Of importance, PHD1 protein was expressed in HSCs within human livers, and PHD1 transcript expression was significantly increased with disease severity in hepatic tissue from patients with liver fibrosis. Collectively, these findings indicate that PHD1 deficiency protects against liver fibrosis and that these effects are partly due to attenuated activation of HSCs. PHD1 may represent a therapeutic target to alleviate liver fibrosis.

Liver fibrosis

Liver fibrosis is a wound-healing response generated against an insult to the liver that causes liver injury. It has the potential to progress into cirrhosis, and if not prevented, it may lead to liver cancer and liver failure. The activation of hepatic stellate cells (HSCs) is the central event underlying liver fibrosis. In addition to HSCs, numerous studies have supported the potential contribution of bone marrow-derived cells and myofibroblasts to liver fibrosis. The liver is a heterogeneous organ; thus, molecular and cellular events that underlie liver fibrogenesis are complex. This review aims to focus on major events that occur during liver fibrogenesis. In addition, important antifibrotic therapeutic approaches and experimental liver fibrosis models will be discussed.

Endotoxin regulates matrix genes increasing reactive oxygen species generation by intercellular communication between palmitate-treated hepatocyte and stellate cell

Previous studies have shown that gut-derived bacterial endotoxins contribute in the progression of simple steatosis to steatohepatitis, although the mechanism(s) remains inaccurate to date. As hepatic stellate cells (HSC) play a pivotal role in the accumulation of excessive extracellular matrix (ECM), leading to collagen deposition, fibrosis, and perpetuation of inflammatory response, an in vitro model was developed to investigate the crosstalk between HSC and hepatocytes (human hepatoma cell) pretreated with palmitate. Bacterial lipopolysaccharide (LPS) stimulated HSC with phosphorylation of the p38 mitogen-activated protein kinase/NF-κB pathway, while several important pro-inflammatory cytokines were upregulated in the presence of hepatocyte-HSC. Concurrently, fibrosis-related genes were regulated by palmitate and the inflammatory effect of endotoxin where cells were more exposed or sensitive to reactive oxygen species (ROS). This interaction was accompanied by increased expression of the mitochondrial master regulator, proliferator-activated receptor gamma coactivator alpha, and a cytoprotective effect of the agent N-acetylcysteine suppressing ROS production, transforming growth factor-β1, and tissue inhibitor of metalloproteinase-1. In summary, our results demonstrate that pro-inflammatory mediators LPS-induced promote ECM rearrangement in hepatic cells transcriptionally committed to the regulation of genes encoding enzymes for fatty acid metabolism in light of differences that might require an alternative therapeutic approach targeting ROS regulation.

Soluble CD74 Reroutes MIF/CXCR4/AKT-Mediated Survival of Cardiac Myofibroblasts to Necroptosis

Background Although macrophage migration inhibitory factor ( MIF ) has been demonstrated to mediate cardioprotection in ischemia/reperfusion injury and antagonize fibrotic effects through its receptor, CD 74, the function of the soluble CD 74 receptor ectodomain ( sCD 74) and its interaction with circulating MIF have not been explored in cardiac disease. Methods and Results Cardiac fibroblasts were isolated from hearts of neonatal mice and differentiated into myofibroblasts. Co-treatment with recombinant MIF and sCD 74 induced cell death ( P<0.001), which was mediated by receptor-interacting serine/threonine-protein kinase ( RIP) 1/ RIP 3-dependent necroptosis ( P=0.0376). This effect was specific for cardiac fibroblasts and did not affect cardiomyocytes. Gene expression analyses using microarray and RT - qPCR technology revealed a 4-fold upregulation of several interferon-induced genes upon co-treatment of myofibroblasts with sCD 74 and MIF (Ifi44: P=0.011; Irg1: P=0.022; Clec4e: P=0.011). Furthermore, Western blot analysis confirmed the role of sCD 74 as a modulator of MIF signaling by diminishing MIF -mediated protein kinase B ( AKT) activation ( P=0.0197) and triggering p38 activation ( P=0.0641). We obtained evidence that sCD 74 inhibits MIF -mediated survival pathway through the C-X-C chemokine receptor 4/ AKT axis, enabling the induction of CD 74-dependent necroptotic processes in cardiac myofibroblasts. Preliminary clinical data revealed a lowered sCD 74/ MIF ratio in heart failure patients (17.47±10.09 versus 1.413±0.6244). Conclusions These findings suggest that treatment of cardiac myofibroblasts with sCD 74 and MIF induces necroptosis, offering new insights into the mechanism of myofibroblast depletion during scar maturation. Preliminary clinical data provided first evidence about a clinical relevance of the sCD 74/ MIF axis in heart failure, suggesting that these proteins may be a promising target to modulate cardiac remodeling and disease progression in heart failure.

The HLF/IL-6/STAT3 feedforward circuit drives hepatic stellate cell activation to promote liver fibrosis

BACKGROUND AND AIMS

Liver fibrosis is a wound-healing response that disrupts the liver architecture and function by replacing functional parenchyma with scar tissue. Recent progress has advanced our knowledge of this scarring process, but the detailed mechanism of liver fibrosis is far from clear.

METHODS

The fibrotic specimens of patients and HLF (hepatic leukemia factor)^PB/PB mice were used to assess the expression and role of HLF in liver fibrosis. Primary murine hepatic stellate cells (HSCs) and human HSC line Lx2 were used to investigate the impact of HLF on HSC activation and the underlying mechanism.

RESULTS

Expression of HLF was detected in fibrotic livers of patients, but it was absent in the livers of healthy individuals. Intriguingly, HLF expression was confined to activated HSCs rather than other cell types in the liver. The loss of HLF impaired primary HSC activation and attenuated liver fibrosis in HLF^PB/PB mice. Consistently, ectopic HLF expression significantly facilitated the activation of human HSCs. Mechanistic studies revealed that upregulated HLF transcriptionally enhanced interleukin 6 (IL-6) expression and intensified signal transducer and activator of transcription 3 (STAT3) phosphorylation, thus promoting HSC activation. Coincidentally, IL-6/STAT3 signalling in turn activated HLF expression in HSCs, thus completing a feedforward regulatory circuit in HSC activation. Moreover, correlation between HLF expression and alpha-smooth muscle actin, IL-6 and p-STAT3 levels was observed in patient fibrotic livers, supporting the role of HLF/IL-6/STAT3 cascade in liver fibrosis.

CONCLUSIONS

In aggregate, we delineate a paradigm of HLF/IL-6/STAT3 regulatory circuit in liver fibrosis and propose that HLF is a novel biomarker for activated HSCs and a potential target for antifibrotic therapy.

Mouse models of hepatocellular carcinoma: an overview and highlights for immunotherapy research

Mouse models are the basis of preclinical and translational research in hepatocellular carcinoma (HCC). Multiple methods exist to induce tumour formation in mice, including genetically engineered mouse models, chemotoxic agents, intrahepatic or intrasplenic injection of tumour cells and xenograft approaches. Additionally, as HCC generally develops in the context of diseased liver, methods exist to induce liver disease in mice to mimic viral hepatitis, fatty liver disease, fibrosis, alcohol-induced liver disease and cholestasis. Similar to HCC in humans, response to therapy in mouse models is monitored with imaging modalities such as CT or MRI, as well as additional techniques involving bioluminescence. As immunotherapy is increasingly applied to HCC, mouse models for these approaches are required for preclinical data. In studying cancer immunotherapy, it is important to consider aspects of antitumour immune responses and to produce a model that mimics the complexity of the immune system. This Review provides an overview of the different mouse models of HCC, presenting techniques to prepare an HCC mouse model and discussing different approaches to help researchers choose an appropriate model for a specific hypothesis. Specific aspects of immunotherapy research in HCC and the applied mouse models in this field are also highlighted.

Targeting Endothelial Erk1/2-Akt Axis as a Regeneration Strategy to Bypass Fibrosis during Chronic Liver Injury in Mice

Liver sinusoidal endothelial cells (LSECs) have great capacity for liver regeneration, and this capacity can easily switch to profibrotic phenotype, which is still poorly understood. In this study, we elucidated a potential target in LSECs for regenerative treatment that can bypass fibrosis during chronic liver injury. Proregenerative LSECs can be transformed to profibrotic phenotype after 4 weeks of carbon tetrachloride administration or 10 days of bile duct ligation. This phenotypic alternation of LSECs was mediated by extracellular regulated protein kinases 1 and 2 (Erk1/2)-Akt axis switch in LSECs during chronic liver injury; Erk1/2 was normally associated with maintenance of the LSEC proregenerative phenotype, inhibiting hepatic stellate cell (HSC) activation and promoting tissue repair by enhancing nitric oxide (NO)/reactive oxygen species (ROS) ratio and increasing expression of hepatic growth factor (HGF) and Wingless-type MMTV integration site family member 2 (Wnt2). Alternatively, Akt induced LSEC profibrotic phenotype, which mainly stimulated HSC activation and concomitant senescence by reducing NO/ROS ratio and decreasing HGF/Wnt2 expression. LSEC-targeted adenovirus or drug particle to promote Erk1/2 activity can alleviate liver fibrosis, accelerate fibrosis resolution, and enhance liver regeneration. This study demonstrated that the Erk1/2-Akt axis acted as a switch to regulate the proregenerative and profibrotic phenotypes of LSECs, and targeted therapy promoted liver regeneration while bypassing fibrosis, providing clues for a more effective treatment of liver diseases.

The congenital clubfoot - immunohistological analysis of the extracellular matrix

Purpose

Congenital clubfoot is one of the most common limb disorders in humans and its etiology is still unclear. In order to better understand the pathogenesis of patients with primary clubfoot, we examined whether there are quantitative changes in the extracellular matrix (ECM; based on common interstitial collagens [C] like CI and CIII, microfilamentous collagens like CVI, noncollagenous proteins like undulin, and enzymes like matrixmetalloproteinase [MMP]-2 and tissue inhibitor of matrixmetalloproteinase [TIMP]-2 that are known to play a role in fibrogenesis and fibrolysis) of muscles involved in the foot deformity of patients with primary clubfoot corresponding to fibrosis.

Patients and methods

Thirty patients (age ranging from 4 months to 5 years and 7 months) with primary clubfoot were examined (23 male and 7 female patients), among whom 18 patients were affected on one side and 12 affected on both sides. Twenty-five biopsies were taken during the first operative foot correction (Crawford-McKay) and 5 in the context of relapses. Muscle biopsies were taken from the muscles involved in the defect (Musculus [M.] gastrocnemius and M. tibialis anterior) and from the M. vastus lateralis of the M. quadriceps femoris, which were treated as healthy comparison muscles. Quantitative analysis of the components of the ECM was performed using a computer-assisted fibrosis measurement of the immunohistochemically processed tissue samples.

Results

We found higher values for M. gastrocnemius for CI, CIII, CVI and undulin in comparison with M. vastus lateralis. However, values for TIMP-2 were reduced. We found no significant differences for the components of M. tibialis anterior and M. vastus lateralis. There were no quantitative differences between male and female or between patients affected on one side and both sides. In patients who underwent relapse surgery, CI, CIII, CVI, and undulin of the gastrocnemius were significantly higher, while TIMP-2 was significantly lower.

Conclusion

In the present study, we found manifest fibrosis in gastrocnemius due to quantitative changes in the ECM. In contrast to other studies, we found increasing fibrosis not just in contracted tissues but also in the muscle itself. Further studies are needed to clarify whether these changes are primarily responsible for the malfunction or whether they occur secondarily in the consequence of the dysfunction.

Animal models of portal hypertension

Chronic liver diseases ultimately lead to cirrhosis and portal hypertension (PHT). Indeed, PHT is a major cause of severe complications, while medical treatment is limited to non-selective beta blockers. Sophisticated animal models are needed to investigate novel treatment options for different etiologies of liver disease, effective anti-fibrotic agents as well as vasoactive drugs against PHT. In this review, we present some of the most common animal models of liver disease and PHT - including pre-hepatic, intra-hepatic and post-hepatic PHT in rodents. Methodology for induction, considerations for disease etiology, advantages and limitations and practical issues of these animal models are discussed. The appropriate and sensible use of animal models in preclinical research supporting the 3R concept of replacement, reduction and refinement is highlighted.

Stellate Cells in Tissue Repair, Inflammation, and Cancer

Stellate cells are resident lipid-storing cells of the pancreas and liver that transdifferentiate to a myofibroblastic state in the context of tissue injury. Beyond having roles in tissue homeostasis, stellate cells are increasingly implicated in pathological fibrogenic and inflammatory programs that contribute to tissue fibrosis and that constitute a growth-permissive tumor microenvironment. Although the capacity of stellate cells for extracellular matrix production and remodeling has long been appreciated, recent research efforts have demonstrated diverse roles for stellate cells in regulation of epithelial cell fate, immune modulation, and tissue health. Our present understanding of stellate cell biology in health and disease is discussed here, as are emerging means to target these multifaceted cells for therapeutic benefit.

Hepatic elastin content is predictive of adverse outcome in advanced fibrotic liver disease

AIMS

The aim of this study was to determine if elastin content in needle core native liver biopsies was predictive of clinical outcome in patients with chronic hepatitis C virus-related chronic liver disease.

METHODS AND RESULTS

Elastin contents in liver biopsies were determined by image analysis, technically validated in an independent centre, and correlated with outcome in patients with advanced (Ishak stage ≥5) chronic hepatitis C virus-related chronic liver disease. Elastin was robustly quantified in an operator-independent and laboratory-independent manner, with very strong correlation of elastin staining measured with two methods of image classification (rs = 0.873, P < 0.00001). Elastin content (but not absolute scar content or Ishak stage) was predictive for future clinical outcomes. In a cohort of patients without sustained virological response, the median hepatic elastin content was 3.4%, and 17 patients (57%) progressed to a liver-related clinical outcome; 11 of the 15 patients (73%) with a hepatic elastin content of >3.4% progressed to a clinical outcome, as compared with only six of 15 (40%) with an elastin content of <3.4%. The difference in time to outcome was significant.

CONCLUSIONS

We describe a simple and reproducible method for elastin quantification in liver biopsies that provides potentially valuable prognostic information to inform clinical management.

Protective Effect of Octylmethoxycinnamate against UV-Induced Photoaging in Hairless Mouse via the Regulation of Matrix Metalloproteinases

Ultraviolet (UV) irradiation damages skin and produces symptoms of photoaging, such as thickening, rough texture, wrinkles, and pigmentation. However, the cellular and molecular mechanisms underlying photoaging induced by chronic UV irradiation are not yet fully understood. Matrix metalloproteinases (MMPs) have been reported to be involved in the response to UV irradiation. In this study, we examined the effects of the sunscreen agent Octylmethoxycinnamate (OMC) on photoaging of the skin induced by chronic UV exposure in hairless albino Crl:SKH1-Hrhr (SKH-1) mice. We demonstrated that the expression of MMPs was elevated by UV irradiation, whereas the topical application of OMC inhibited the upregulation of MMPs. Furthermore, UV-induced wrinkle formation was decreased by OMC treatment. These results suggest that OMC is a potential agent for the prevention and treatment of skin photoaging.

11Beta-hydroxysteroid dehydrogenase-1 deficiency or inhibition enhances hepatic myofibroblast activation in murine liver fibrosis

A hallmark of chronic liver injury is fibrosis, with accumulation of extracellular matrix orchestrated by activated hepatic stellate cells (HSCs). Glucocorticoids limit HSC activation in vitro, and tissue glucocorticoid levels are amplified by 11beta-hydroxysteroid dehydrogenase-1 (11βHSD1). Although 11βHSD1 inhibitors have been developed for type 2 diabetes mellitus and improve diet-induced fatty liver in various mouse models, effects on the progression and/or resolution of liver injury and consequent fibrosis have not been characterized. We have used the reversible carbon tetrachloride-induced model of hepatocyte injury and liver fibrosis to show that in two models of genetic 11βHSD1 deficiency (global, Hsd11b1-/- , and hepatic myofibroblast-specific, Hsd11b1fl/fl /Pdgfrb-cre) 11βHSD1 pharmacological inhibition in vivo exacerbates hepatic myofibroblast activation and liver fibrosis. In contrast, liver injury and fibrosis in hepatocyte-specific Hsd11b1fl/fl /albumin-cre mice did not differ from that of controls, ruling out 11βHSD1 deficiency in hepatocytes as the cause of the increased fibrosis. In primary HSC culture, glucocorticoids inhibited expression of the key profibrotic genes Acta2 and Col1α1, an effect attenuated by the 11βHSD1 inhibitor [4-(2-chlorophenyl-4-fluoro-1-piperidinyl][5-(1H-pyrazol-4-yl)-3-thienyl]-methanone. HSCs from Hsd11b1-/- and Hsd11b1fl/fl /Pdgfrb-cre mice expressed higher levels of Acta2 and Col1α1 and were correspondingly more potently activated. In vivo [4-(2-chlorophenyl-4-fluoro-1-piperidinyl][5-(1H-pyrazol-4-yl)-3-thienyl]-methanone administration prior to chemical injury recapitulated findings in Hsd11b1-/- mice, including greater fibrosis.

CONCLUSION

11βHSD1 deficiency enhances myofibroblast activation and promotes initial fibrosis following chemical liver injury; hence, the effects of 11βHSD1 inhibitors on liver injury and repair are likely to be context-dependent and deserve careful scrutiny as these compounds are developed for chronic diseases including metabolic syndrome and dementia. (Hepatology 2018;67:2167-2181).

Hepatic fibrosis: It is time to go with hepatic stellate cell-specific therapeutic targets

Hepatic fibrosis is a pathological lesion, characterized by the progressive accumulation of extracellular matrix (ECM) in the perisinusoidal space and it is a major problem in chronic liver diseases. Phenotypic activation of hepatic stellate cells (HSC) plays a central role in the progression of hepatic fibrosis. Retardation of proliferation and clearance of activated HSCs from the injured liver is an appropriate therapeutic strategy for the resolution and treatment of hepatic fibrosis. Clearance of activated HSCs from the injured liver by autophagy inhibitors, proapoptotic agents and senescence inducers with the high affinity toward the activated HSCs may be the novel therapeutic strategy for the treatment of hepatic fibrosis in the near future.

Triggering and resolution of inflammation in NASH

Nonalcoholic steatohepatitis (NASH) is considered the progressive form of nonalcoholic fatty liver disease (NAFLD) and is characterized by liver steatosis, inflammation, hepatocellular injury and different degrees of fibrosis. A central issue in this field relates to the identification of those factors that trigger inflammation, thus fuelling the transition from nonalcoholic fatty liver to NASH. These triggers of liver inflammation might have their origins outside the liver (such as in adipose tissue or the gut) as well as inside the organ (for instance, lipotoxicity, innate immune responses, cell death pathways, mitochondrial dysfunction and endoplasmic reticulum stress), both of which contribute to NASH development. In this Review, we summarize the currently available information on the key upstream triggers of inflammation in NASH. We further delineate the mechanisms by which liver inflammation is resolved and the implications of a defective pro-resolution process. A better knowledge of these mechanisms should help to design targeted therapies able to halt or reverse disease progression.

Acute lung injury by gastric fluid instillation: activation of myofibroblast apoptosis during injury resolution

BACKGROUND

Gastric contents aspiration in humans has variable consequences depending on the volume of aspirate, ranging from subclinical pneumonitis to respiratory failure with up to 70% mortality. Several experimental approaches have been used to study this condition. In a model of single orotracheal instillation of gastric fluid we have shown that severe acute lung injury evolves from a pattern of diffuse alveolar damage to one of organizing pneumonia (OP), that later resolves leaving normal lung architecture. Little is known about mechanisms of injury resolution after a single aspiration that could be dysregulated with repetitive aspirations. We hypothesized that, in a similar way to cutaneous wound healing, apoptosis may participate in lung injury resolution by reducing the number of myofibroblasts and by affecting the balance between proteases and antiproteases. Our aim was to study activation of apoptosis as well as MMP-2/TIMP-2 balance in the sub-acute phase (4-14 days) of gastric fluid-induced lung injury.

METHODS

Anesthesized Sprague-Dawley rats received a single orotracheal instillation of gastric fluid and were euthanized 4, 7 and 14 days later (n = 6/group). In lung tissue we studied caspase-3 activation and its location by double immunofluorescence for cleaved caspase-3 or TUNEL and alpha-SMA. MMP-2/TIMP-2 balance was studied by zymography and Western blot. BALF levels of TGF-β₁ were measured by ELISA.

RESULTS

An OP pattern with Masson bodies and granulomas was seen at days 4 and 7 that was no longer present at day 14. Cleaved caspase-3 increased at day 7 and was detected by immunofluorescence in Masson body-alpha-SMA-positive and -negative cells. TUNEL-positive cells at days 4 and 7 were located mainly in Masson bodies. Distribution of cleaved caspase-3 and TUNEL-positive cells at day 14 was similar to that in controls. At the peak of apoptosis (day 7), an imbalance between MMP-2 activity and TIMP-2 expression was produced by reduction in TIMP-2 expression.

CONCLUSIONS

Apoptosis is activated in Masson body-alpha-SMA-positive and -negative cells during the sub-acute phase of gastric fluid-induced lung injury. This mechanism likely contributes to OP resolution, by reducing myofibroblast number and new collagen production. In addition, pre-formed collagen degradation is favored by an associated MMP-2/TIMP-2 imbalance.

Are we any closer to treating liver fibrosis (and if no, why not)?

This review provides a personal view on anti-fibrosis therapy in the liver. The worst clinical consequence of liver fibrosis is the development of liver cirrhosis and portal hypertension. Etiology is a decisive factor which determines patterns of fibrous septa and subsequent vascular remodeling, which is essential for the development of portal hypertension. Removing or controlling the disease-causing agent, i.e. anti-viral treatment for hepatitis, is the essential first step for treating chronic liver diseases and can reverse fibrosis in some settings. However, removing etiology is not always sufficient to prevent fibrosis from progressing towards cirrhosis and portal hypertension. In liver diseases such as severe alcoholic hepatitis and massive parenchymal loss, the formation of vascular anastomoses between portal to central veins based on bridging fibrosis results in cirrhosis and portal hypertension. For these patients, anti-fibrotic treatment is crucial and urgent. Unfortunately, a lack of understanding how fibrosis contributes to vascular remodeling caused by and combined with a lack of suitable experimental models that recapitulate human liver diseases, has hampered the development of successful anti-fibrotic drugs for clinical use to date.

Prospects in non-invasive assessment of liver fibrosis: Liquid biopsy as the future gold standard?

Liver fibrosis is the result of persistent liver injury, and is characterized by sustained scar formation and disruption of the normal liver architecture. The extent of fibrosis is considered as an important prognostic factor for the patient outcome, as an absence of (early) treatment can lead to the development of liver cirrhosis and hepatocellular carcinoma. Till date, the most sensitive and specific way for the diagnosis and staging of liver fibrosis remains liver biopsy, an invasive diagnostic tool, which is associated with high costs and discomfort for the patient. Over time, non-invasive scoring systems have been developed, of which the measurements of serum markers and liver stiffness are validated for use in the clinic. These tools lack however the sensitivity and specificity to detect small changes in the progression or regression of both early and late stages of fibrosis. Novel non-invasive diagnostic markers with the potential to overcome these limitations have been developed, but often lack validation in large patient cohorts. In this review, we will summarize novel trends in non-invasive markers of liver fibrosis development and will discuss their (dis-)advantages for use in the clinic.

Resolution of organ fibrosis

Fibrosis is the excessive accumulation of extracellular matrix that often occurs as a wound healing response to repeated or chronic tissue injury, and may lead to the disruption of organ architecture and loss of function. Although fibrosis was previously thought to be irreversible, recent evidence indicates that certain circumstances permit the resolution of fibrosis when the underlying causes of injury are eradicated. The mechanism of fibrosis resolution encompasses degradation of the fibrotic extracellular matrix as well as elimination of fibrogenic myofibroblasts through their adaptation of various cell fates, including apoptosis, senescence, dedifferentiation, and reprogramming. In this Review, we discuss the present knowledge and gaps in our understanding of how matrix degradation is regulated and how myofibroblast cell fates can be manipulated, areas that may identify potential therapeutic approaches for fibrosis.

Impact of the Microenvironment on Tumour Budding in Colorectal Cancer

Tumour Budding (TB) is recognized as an adverse prognostic factor in colorectal cancer (CRC). TB is the detachment of isolated cancer cells or small clusters of such cells mainly at the invasion front. One question that arises is of the role of the tumour stroma regarding the permissiveness of the formation and progression of TB. In this review, we will examine potential factors affecting TB, in particular we will analyse the potential effect of inflammation, hypoxia, extracellular matrix and Cancer-Associated Fibroblasts (CAFs).

Succinate as a Regulator of Hepatic Stellate Cells in Liver Fibrosis

The rapid increase of obesity rates worldwide is associated with chronic liver injury due to non-alcoholic fatty liver disease and non-alcoholic steatohepatitis. Chronic liver inflammation drives hepatic fibrosis, which is a highly conserved and coordinated protective response to tissue injury, and is a reversible process. Hepatocytes, immune cells, and hepatic stellate cells (HSCs) have been identified as key players in the mechanisms of hepatic fibrosis and inflammation. During the last decade, succinate, an intermediate of the tricarboxylic acid cycle in mitochondrial ATP production, has emerged as an important signaling molecule in various diseases. Succinate acts as an extracellular ligand for G-protein coupled receptor 91, also known as succinate receptor 1, which is mainly expressed in the kidney, heart, liver, immune cells, and retinal cells, suggesting a widespread function in cellular metabolism. Furthermore, succinate stabilizes hypoxia-inducible factor-1α in immune cells and tumors as a signaling molecule, and has been shown to post-translationally modify proteins. This review summarizes the recent evidence pointing to an additional role of succinate in profibrotic signaling, along with its downstream signaling pathways, and updates the current state of knowledge on the role of succinate in liver fibrosis through its action on HSCs. Further focus on this link can help identify succinate, its receptor, and its downstream signaling molecules as new targets for the treatment of liver fibrosis.