CCR2 promotes hepatic fibrosis in mice

Curcumin reduces Ly6Chi monocyte infiltration to protect against liver fibrosis by inhibiting Kupffer cells activation to reduce chemokines secretion

Curcumin has been reported to have anti-fibrotic effect. However, the anti-fibrotic mechanism of curcumin for liver fibrosis remains obscure. In the presenting study, we aimed to investigate whether curcumin reduce chemokines secretion by inhibiting kupffer cells (KCs) activation to decrease Ly6C^hi monocyte infiltration in the treatment of liver fibrosis. Liver fibrosis was induced by intraperitoneal carbon tetrachloride (CCl₄)-injection in mice. Mice in curcumin group received curcumin treatment by gavage. Pretreatment with curcumin significantly protected mice from liver inflammation and fibrosis. Compared to CCl₄ group, mice in the curcumin group showed significantly less intrahepatic infiltration of Ly6C^hi monocytes, but no difference of other leucocyte subtypes. Moreover, curcumin significantly reduced Ly6C^hi monocytes associated pro-inflammatory and pro-fibrogenic cytokines, which was in line with the decreased numbers of intrahepatic Ly6C^hi monocytes. Further study found that curcumin is able to decrease KCs activation and monocyte chemokines, which explains why curcumin can reduce Ly6C^hi monocytes infiltration during liver fibrosis. In vitro, we discovered that curcumin prevents the polarization of macrophages toward M1 and reduces monocyte chemokines secretion, which is involved with ERK1/2 and p38 pathways. Taken together, for the first time, we verified that curcumin can reduce chemokines secretion by inhibiting KCs activation to decrease Ly6C^hi monocyte infiltration in the treatment of liver fibrosis. These results suggested that curcumin may be considered a promising candidate in the prevention and treatment of liver fibrosis.

Primary cilia disruption differentially affects the infiltrating and resident macrophage compartment in the liver

Hepatorenal fibrocystic disease (HRFCD) is characterized by cysts in the kidney and liver with associated fibrosis and is the result of defects in proteins required for cilia function or assembly. Previous reports indicate that macrophages, mainly M2-like macrophages, contribute to HRFCD, although the origin of these cells (yolk sac-derived resident macrophages vs. bone marrow-derived infiltrating macrophages) and their contribution to the observed phenotypes are unknown. We utilize a congenital model of cilia dysfunction (IFT88^Orpk) to study the importance of macrophages in HRFCD. Our data show a rapid expansion of the bile duct region and development of fibrosis between 2 and 4 wk of age. Immunofluorescence microscopy analysis reveals an accumulation of F4/80⁺ macrophages in regions exhibiting biliary hyperplasia in IFT88^Orpk mice. Flow cytometry data show that cilia dysfunction leads to an accumulation of infiltrating macrophages (CD11b^hi, F4/80^lo) and a reduction of resident macrophage (CD11b^lo, F4/80^hi) number. A majority of the infiltrating macrophages are Ly6c^hi profibrogenic macrophages. Along with the accumulation of immune cells, expression of proinflammatory and profibrotic transcripts, including TGF-β, TNF-α, IL-1β, and chemokine (C-C) motif ligand 2, is increased. Quantitative RT-PCR analysis of flow-sorted cells shows enhanced expression of CCL2 in cholangiocytes and enhanced expression of VEGF-A and IL-6 in Ly6c^hi macrophages. Genetic inhibition of Ly6c^hi macrophage accumulation in IFT88^Orpk FVB CCR2^-/- mice reduced biliary fibrosis but did not affect epithelial expansion. Collectively, these studies suggest that biliary epithelium with defects in primary cilia preferentially recruits Ly6c^hi infiltrating macrophages, which promote fibrotic progression in HRFCD pathogenesis. NEW & NOTEWORTHY These studies are the first to address the contribution of the infiltrating and resident macrophage niche during progression of hepatorenal fibrocystic disease (HRFCD). We show that the number of infiltrating macrophages is significantly upregulated in HRFCD mouse models. Finally, we show that prevention of Ly6c^hi infiltrating macrophage accumulation significantly reduces biliary fibrosis, but not biliary hyperplasia, suggesting that this population may be responsible for the fibrotic progression of the disease in HRFCD patients.

Cenicriviroc, a cytokine receptor antagonist, potentiates all-trans retinoic acid in reducing liver injury in cholestatic rodents

BACKGROUND & AIMS

Cholestatic liver injury is mediated by bile acid-induced inflammatory responses. We hypothesized that superior therapeutic effects might be achieved by combining treatments that reduce the bile acid pool size with one that blocks inflammation.

METHODS

Bile duct-ligated (BDL) rats and Mdr2(Abcb4)-/- mice were treated with all-trans retinoic acid (atRA), a potent inhibitor of bile acid synthesis, 5 mg/kg/d by gavage, or Cenicriviroc (CVC), a known antagonist of CCR2 and CCR5, 50 mg/kg/d alone or in combination for 14 days and 1 month respectively.

RESULTS

All-trans retinoic acid alone reduced bile acid pool size and liver necrosis in BDL rats. However, the combination with CVC further reduced liver to body weight ratio, bile acid pool size, plasma liver enzyme, bilirubin, liver necrosis and fibrosis when compared to the atRA treatment. The assessment of hepatic hydroxyproline content further confirmed the reduced liver injury concurrent with reduction of pro-inflammatory cytokines emphasizing the synergistic effects of these two agents. Profiling of hepatic inflammatory cells revealed that combination therapy reduced neutrophils and T cells but not macrophages. The superior therapeutic effects of combination treatment were also confirmed in Mdr2-/- mice where a significant reduction in plasma liver enzymes, bilirubin, liver fibrosis, bile duct proliferation and hepatic infiltration of neutrophils and T cells and expression of cytokines were found.

CONCLUSIONS

Multitargeted therapy is an important paradigm for treating cholestatic liver injury. The combination of CVC with atRA or other FXR activators may warrant a clinical trial in patients with cholestatic liver disease.

Myeloid-specific targeting of Notch ameliorates murine renal fibrosis via reduced infiltration and activation of bone marrow-derived macrophage

Macrophages play critical roles in renal fibrosis. However, macrophages exhibit ontogenic and functional heterogeneities, and which population of macrophages contributes to renal fibrosis and the underlying mechanisms remain unclear. In this study, we genetically targeted Notch signaling by disrupting the transcription factor recombination signal binding protein-Jκ (RBP-J), to reveal its role in regulation of macrophages during the unilateral ureteral obstruction (UUO)-induced murine renal fibrosis. Myeloid-specific disruption of RBP-J attenuated renal fibrosis with reduced extracellular matrix deposition and myofibroblast activation, as well as attenuated epithelial-mesenchymal transition, likely owing to the reduced expression of TGF-β. Meanwhile, RBP-J deletion significantly hampered macrophage infiltration and activation in fibrotic kidney, although their proliferation appeared unaltered. By using macrophage clearance experiment, we found that kidney resident macrophages made negligible contribution, but bone marrow (BM)-derived macrophages played a major role in renal fibrogenesis. Further mechanistic analyses showed that Notch blockade reduced monocyte emigration from BM by down-regulating CCR2 expression. Finally, we found that myeloid-specific Notch activation aggravated renal fibrosis, which was mediated by CCR2⁺ macrophages infiltration. In summary, our data have unveiled that myeloid-specific targeting of Notch could ameliorate renal fibrosis by regulating BM-derived macrophages recruitment and activation, providing a novel strategy for intervention of this disease.

Macrophage-derived IL-1β/NF-κB signaling mediates parenteral nutrition-associated cholestasis

In infants intolerant of enteral feeding because of intestinal disease, parenteral nutrition may be associated with cholestasis, which can progress to end-stage liver disease. Here we show the function of hepatic macrophages and phytosterols in parenteral nutrition-associated cholestasis (PNAC) pathogenesis using a mouse model that recapitulates the human pathophysiology and combines intestinal injury with parenteral nutrition. We combine genetic, molecular, and pharmacological approaches to identify an essential function of hepatic macrophages and IL-1β in PNAC. Pharmacological antagonism of  IL-1 signaling or genetic deficiency in CCR2, caspase-1 and caspase-11, or IL-1 receptor (which binds both IL-1α and IL-1β) prevents PNAC in mice. IL-1β increases hepatocyte NF-κB signaling, which interferes with farnesoid X receptor and liver X receptor bonding to respective promoters of canalicular bile and sterol transporter genes (Abcc2, Abcb11, and Abcg5/8), resulting in transcriptional suppression and subsequent cholestasis. Thus, hepatic macrophages, IL-1β, or NF-κB may be targets for restoring bile and sterol transport to treat PNAC.

Emodin Alleviates Liver Fibrosis of Mice by Reducing Infiltration of Gr1hi Monocytes

Emodin, as a major active component of Rheum palmatum L. and Polygonum cuspidatum, has been reported to have antifibrotic effect. However, the mechanism of emodin on antifibrotic effect for liver fibrosis was still obscure. In the present study, we aimed to investigate whether emodin can alleviate carbon tetrachloride- (CCl₄-) induced liver fibrosis through reducing infiltration of Gr1^hi monocytes. Liver fibrosis was induced by intraperitoneal CCl₄ injection in mice. Mice in the emodin group received emodin treatment by gavage. Pretreatment with emodin significantly protected mice from liver inflammation and fibrosis revealed by the decreased elevation of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), as well as reduced hepatic necrosis and fibrosis by analysis of hematoxylin-eosin (HE) staining, Masson staining, α-smooth muscle actin (α-SMA), and collagen-I immunohistochemistry staining. Further, compared to CCl₄ group, mice in the emodin group showed significantly less intrahepatic infiltration of Gr1^hi monocytes. Moreover, emodin significantly inhibited hepatic expression of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), granulin (GRN), monocyte chemoattractant protein 1 (MCP-1), and chemokine ligand 7 (CCL7), which was in line with the decreased numbers of intrahepatic Gr1^hi monocytes. In conclusion, emodin can alleviate the degree of liver fibrosis by reducing infiltration of Gr1^hi monocytes. These results suggest that emodin is a promising candidate to prevent and treat liver fibrosis.

Cenicriviroc for the treatment of non-alcoholic steatohepatitis and liver fibrosis

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) has an increasing prevalence worldwide. At present, no specific pharmacotherapy is approved for NAFLD. Simple steatosis and nonalcoholic steatohepatitis (NASH) can progress to liver fibrosis that is associated with mortality in NAFLD. The recruitment of inflammatory monocytes and macrophages via chemokine receptor CCR2 as well as of lymphocytes and hepatic stellate cells via CCR5 promote the progression of NASH to fibrosis. Areas covered: I summarize preclinical and clinical data on the efficacy and safety of the dual CCR2/CCR5 inhibitor cenicriviroc (CVC, also TBR-652 or TAK-652) for the treatment of NASH and fibrosis. In animal models of liver diseases, CVC potently inhibits macrophage accumulation in the liver and ameliorates fibrosis. In a phase 2b clinical trial (CENTAUR) on 289 patients with NASH and fibrosis, CVC consistently demonstrated liver fibrosis improvement after 1 year of therapy and had an excellent safety profile, leading to the implementation of a phase 3 trial (AURORA). Expert opinion: Preclinical and clinical data support the development of CVC as a safe and potent antifibrotic agent. However, open questions around CVC are the durability of antifibrotic responses, divergent effects on NASH versus fibrosis, potential long-term concerns and the expected path to approval.

EphB2 receptor tyrosine kinase promotes hepatic fibrogenesis in mice via activation of hepatic stellate cells

Hepatic fibrosis is the result of an excessive wound-healing response subsequent to chronic liver injury. A feature of liver fibrogenesis is the secretion and deposition of extracellular matrix proteins by activated hepatic stellate cells (HSCs). Here we report that upregulation of EphB2 is a prominent feature of two mouse models of hepatic fibrosis and also observed in humans with liver cirrhosis. EphB2 is upregulated and activated in mouse HSCs following chronic carbon tetrachloride (CCl₄) exposure. Moreover, we show that EphB2 deficiency attenuates liver fibrosis and inflammation and this is correlated with an overall reduction in pro-fibrotic markers, inflammatory chemokines and cytokines. In an in vitro system of HSCs activation we observed an impaired proliferation and sub-optimal differentiation into fibrogenic myofibroblasts of HSCs isolated from EphB2-/- mice compared to HSCs isolated from wild type mice. This supports the hypothesis that EphB2 promotes liver fibrosis partly via activation of HSCs. Cellular apoptosis which is generally observed during the regression of liver fibrogenesis was increased in liver specimens of CCl₄-treated EphB2-/- mice compared to littermate controls. This data is suggestive of an active repair/regeneration system in the absence of EphB2. Altogether, our data validate this novel pro-fibrotic function of EphB2 receptor tyrosine kinase.

Pharmacotherapy for NASH: Current and emerging

Non-alcoholic fatty liver disease (NAFLD) has become one of the most prominent forms of chronic liver disease worldwide, reflecting the epidemic of global obesity. Those with the progressive variant of NAFLD, non-alcoholic steatohepatitis (NASH), are at significantly increased risk of multisystem morbidity and mortality. However, there are currently no approved pharmacologic therapies for NASH. Given the disease burden, there is an important unmet need for pharmacologic treatment options for this patient population. The underlying pathophysiologic mechanisms that contribute to the development and progression of NAFLD and NASH are complex and reflected by the myriad of therapies, with different targets, currently under investigation. In broad strokes, drug development has focused on modulation of metabolic pathways, inflammatory cascades, and/or mechanisms impacting fibrosis. Although much progress has been made in enhancing our understanding of NAFLD pathogenesis, development of pharmacologic treatments has been hindered by challenges in clinical trial enrollment and complexities in clinical trial design. The compounds in phase IIa have provided promising results in terms of potential benefits on various aspects of histopathology. Agents in later stages of development have shown fairly modest results in terms of reduction of hepatic steatosis, necroinflammation and fibrosis. If longer term safety and efficacy are established among heterogeneous cohorts, these medications may help mitigate potential morbidity and mortality for this burgeoning patient population.

Dietary NaCl affects bleomycin-induced lung fibrosis in mice

PURPOSE

High levels of NaCl in the diet are associated with both cardiac and renal fibrosis, but whether salt intake affects pulmonary fibrosis has not been examined.

AIM OF THE STUDY

To test the hypothesis that salt intake might affect pulmonary fibrosis.

MATERIALS AND METHODS

Mice were fed low, normal, or high salt diets for 2 weeks, and then treated with oropharyngeal bleomycin to induce pulmonary fibrosis, or oropharyngeal saline as a control.

RESULTS

As determined by collagen staining of lung sections, and protein levels and cell numbers in the bronchoalveolar lavage (BAL) fluid at 21 days after bleomycin, the high salt diet did not exacerbate bleomycin-induced fibrosis, while the low salt diet attenuated fibrosis. For the bleomycin-treated mice, staining of the post-BAL lung sections indicated that compared to the regular salt diet, high salt increased the number of Ly6c-positive macrophages and decreased the number of CD11c and CD206-positive macrophages and dendritic cells. The low salt diet caused bleomycin-induced leukocyte numbers to be similar to control saline-treated mice, but reduced numbers of CD45/collagen-VI positive fibrocytes. In the saline controls, low dietary salt decreased CD11b and CD11c positive cells in lung sections, and high dietary salt increased fibrocytes.

CONCLUSIONS

Together, these data suggest the possibility that a low salt diet might attenuate pulmonary fibrosis.

Inhibitory effect of silymarin on CCl4-induced liver fibrosis by reducing Ly6Chi monocytes infiltration

It has been well established that silymarin has hepatoprotective and anti-fibrotic effects. But the mechanisms are poorly understood. In recent years, the role of Ly6C^hi monocytes in liver fibrosis has been well demonstrated. Thus, in present study we aimed to investigate whether silymarin can relieve liver fibrosis by reducing Ly6C^hi monocytes infiltration. The mouse model of liver fibrosis was established by injected with carbon tetrachloride (CCl₄) via intraperitoneal repeatedly. Mice in silymarin group received silymarin treatment by gavage. Silymarin significantly reduced liver inflammation and fibrosis of the mice induced by CCl₄ injection, as revealed by liver histological and pathological analysis. Mice administrated by silymarin exhibited less infiltration of Ly6C^hi monocytes. But there was no difference on other tested leukocyte subsets between CCl₄ group and silymarin group. Meanwhile, further study found that silymarin significantly reduced CCl₄-induced increased expression of tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1 and monocyte chemoattractant protein 1 (MCP-1), which was in line with the decreased numbers of intrahepatic Ly6C^hi monocytes. In conclusion, our study showed that the anti-inflammatory and anti-fibrotic effects of silymarin could be contributed to the prevention of Ly6C^hi monocytes infiltration into the injured livers, which will give us a better understanding on the cellular mechanism of hepatoprotective and anti-fibrotic effect for silymarin.

CD11c+ resident macrophages drive hepatocyte death-triggered liver fibrosis in a murine model of nonalcoholic steatohepatitis

Although recent evidence has pointed to the role of organ- and pathogenesis-specific macrophage subsets, it is still unclear which subsets are critically involved in the pathogenesis of nonalcoholic steatohepatitis (NASH). Using melanocortin-4 receptor-deficient (MC4R-KO) mice fed Western diet (WD), which exhibit liver phenotypes similar to those of human NASH, we found a histological structure, termed hepatic crown-like structure (hCLS), in which CD11c+ macrophages surround dead/dying hepatocytes, a prominent feature of NASH. Here, we demonstrate that hCLS-constituting macrophages could be a novel macrophage subset that drives hepatocyte death-triggered liver fibrosis. In an "inducible NASH model," hepatocyte death induces hCLS formation and liver fibrosis sequentially in the short term. In combination with the long-term WD feeding model, we also showed that resident macrophages are a major cellular source of CD11c+ macrophages constituting hCLS, which exhibited gene expression profiles distinct from CD11c- macrophages scattered in the liver. Moreover, depletion of CD11c+ macrophages abolished hCLS formation and fibrogenesis in NASH. Our clinical data suggest the role of CD11c+ macrophages in the disease progression from simple steatosis to NASH. This study sheds light on the role of resident macrophages, in addition to recruited macrophages, in the pathogenesis of NASH.

Treatment options for alcoholic and non-alcoholic fatty liver disease: A review

Alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) are serious health problems worldwide. These two diseases have similar pathological spectra, ranging from simple steatosis to hepatitis to cirrhosis and hepatocellular carcinoma. Although most people with excessive alcohol or calorie intake display abnormal fat accumulation in the liver (simple steatosis), a small percentage develops progressive liver disease. Despite extensive research on understanding the pathophysiology of both these diseases there are still no targeted therapies available. The treatment for ALD remains as it was 50 years ago: abstinence, nutritional support and corticosteroids (or pentoxifylline as an alternative if steroids are contraindicated). As for NAFLD, the treatment modality is mainly directed toward weight loss and co-morbidity management. Therefore, new pathophysiology directed therapies are urgently needed. However, the involvement of several inter-related pathways in the pathogenesis of these diseases suggests that a single therapeutic agent is unlikely to be an effective treatment strategy. Hence, a combination therapy towards multiple targets would eventually be required. In this review, we delineate the treatment options in ALD and NAFLD, including various new targeted therapies that are currently under investigation. We hope that soon we will be having an effective multi-therapeutic regimen for each disease.

Differential impact of the dual CCR2/CCR5 inhibitor cenicriviroc on migration of monocyte and lymphocyte subsets in acute liver injury

A hallmark of acute hepatic injury is the recruitment of neutrophils, monocytes and lymphocytes, including natural killer (NK) or T cells, towards areas of inflammation. The recruitment of leukocytes from their reservoirs bone marrow or spleen into the liver is directed by chemokines such as CCL2 (for monocytes) and CCL5 (for lymphocytes). We herein elucidated the impact of chemokine receptor inhibition by the dual CCR2 and CCR5 inhibitor cenicriviroc (CVC) on the composition of myeloid and lymphoid immune cell populations in acute liver injury. CVC treatment effectively inhibited the migration of bone marrow monocytes and splenic lymphocytes (NK, CD4 T-cells) towards CCL2 or CCL5 in vitro. When liver injury was induced by an intraperitoneal injection of carbon tetrachloride (CCl₄) in mice, followed by repetitive oral application of CVC, flow cytometric and unbiased t-SNE analysis of intrahepatic leukocytes demonstrated that dual CCR2/CCR5 inhibition in vivo significantly decreased numbers of monocyte derived macrophages in acutely injured livers. CVC also reduced numbers of Kupffer cells (KC) or monocyte derived macrophages with a KC-like phenotype, respectively, after injury. In contrast to the inhibitory effects in vitro, CVC had no impact on the composition of hepatic lymphoid cell populations in vivo. Effective inhibition of monocyte recruitment was associated with reduced inflammatory macrophage markers and moderately ameliorated hepatic necroses at 36h after CCl₄. In conclusion, dual CCR2/CCR5 inhibition primarily translates into reduced monocyte recruitment in acute liver injury in vivo, suggesting that this strategy will be effective in reducing inflammatory macrophages in conditions of liver disease.

MerTK Cleavage on Resident Cardiac Macrophages Compromises Repair After Myocardial Ischemia Reperfusion Injury

RATIONALE

Clinical benefits of reperfusion after myocardial infarction are offset by maladaptive innate immune cell function, and therapeutic interventions are lacking.

OBJECTIVE

We sought to test the significance of phagocytic clearance by resident and recruited phagocytes after myocardial ischemia reperfusion.

METHODS AND RESULTS

In humans, we discovered that clinical reperfusion after myocardial infarction led to significant elevation of the soluble form of MerTK (myeloid-epithelial-reproductive tyrosine kinase; ie, soluble MER), a critical biomarker of compromised phagocytosis by innate macrophages. In reperfused mice, macrophage Mertk deficiency led to decreased cardiac wound debridement, increased infarct size, and depressed cardiac function, newly implicating MerTK in cardiac repair after myocardial ischemia reperfusion. More notably, Mertk(CR) mice, which are resistant to cleavage, showed significantly reduced infarct sizes and improved systolic function. In contrast to other cardiac phagocyte subsets, resident cardiac MHCII^LOCCR2^- (major histocompatibility complex II/C-C motif chemokine receptor type 2) macrophages expressed higher levels of MerTK and, when exposed to apoptotic cells, secreted proreparative cytokines, including transforming growth factor-β. Mertk deficiency compromised the accumulation of MHCII^LO phagocytes, and this was rescued in Mertk(CR) mice. Interestingly, blockade of CCR2-dependent monocyte infiltration into the heart reduced soluble MER levels post-ischemia reperfusion.

CONCLUSIONS

Our data implicate monocyte-induced MerTK cleavage on proreparative MHCII^LO cardiac macrophages as a novel contributor and therapeutic target of reperfusion injury.

Placental Growth Factor Contributes to Liver Inflammation, Angiogenesis, Fibrosis in Mice by Promoting Hepatic Macrophage Recruitment and Activation

Placental growth factor (PlGF), a member of the vascular endothelial growth factor (VEGF) family, mediates wound healing and inflammatory responses, exerting an effect on liver fibrosis and angiogenesis; however, the precise mechanism remains unclear. The aims of this study are to identify the role of PlGF in liver inflammation and fibrosis induced by bile duct ligation (BDL) in mice and to reveal the underlying molecular mechanism. PlGF small interfering RNA (siRNA) or non-targeting control siRNA was injected by tail vein starting 2 days after BDL. Liver inflammation, fibrosis, angiogenesis, macrophage infiltration, and hepatic stellate cells (HSCs) activation were examined. Our results showed that PlGF was highly expressed in fibrotic livers and mainly distributed in activated HSCs and macrophages. Furthermore, PlGF silencing strongly reduced the severity of liver inflammation and fibrosis, and inhibited the activation of HSCs. Remarkably, PlGF silencing also attenuated BDL-induced hepatic angiogenesis, as evidenced by attenuated liver endothelial cell markers CD31 and von Willebrand factor immunostaining and genes or protein expression. Interestingly, these pathological ameliorations by PlGF silencing were due to a marked reduction in the numbers of intrahepatic F4/80⁺, CD68⁺, and Ly6C⁺ cell populations, which were reflected by a lower expression of these macrophage marker molecules in fibrotic livers. In addition, knockdown of PlGF by siRNA inhibited macrophages activation and substantially suppressed the expression of pro-inflammatory cytokines and chemokines in fibrotic livers. Mechanistically, evaluation of cultured RAW 264.7 cells revealed that VEGF receptor 1 (VEGFR1) mainly involved in mediating the role of PlGF in macrophages recruitment and activation, since using VEGFR1 neutralizing antibody blocking PlGF/VEGFR1 signaling axis significantly inhibited macrophages migration and inflammatory responses. Together, these findings indicate that PlGF plays an important role in liver inflammation, angiogenesis, and fibrosis by promoting hepatic macrophage recruitment and activation, and suggest that blockage of PlGF could be a promising novel therapy for chronic fibrotic liver diseases.

Histone Demethylation and Toll-like Receptor 8-Dependent Cross-Talk in Monocytes Promotes Transdifferentiation of Fibroblasts in Systemic Sclerosis Via Fra-2

OBJECTIVE

To investigate whether epigenetic changes can modulate monocytes to produce tissue inhibitor of metalloproteinases 1 (TIMP-1) via Fra-2 (an activator protein 1 [AP-1] family member), a novel downstream mediator that promotes fibrogenesis.

METHODS

AP-1 transcription factors and TIMP-1 expression were measured in monocytes from systemic sclerosis (SSc) patients and healthy controls. Involvement of Fra-2 in the regulation of TIMP-1 following treatment with Toll-like receptor 8 (TLR-8) agonist was investigated using a luciferase activity assay and chromatin immunoprecipitation (ChIP) analysis. Expression of TIMP-1 and Fra-2 was determined in response to TLR-8 treatment and to different histone modifications, including 3'-deazaneplanocin (DZNep) and apicidin. Fibroblasts from healthy controls were cocultured with DZNep plus TLR-8-treated healthy control monocytes.

RESULTS

Up-regulation of Fra-2 was detected in bleomycin-challenged mice and in skin biopsy samples from SSc patients. Enhanced expression of Fra-2 and TIMP-1 was correlated in SSc monocytes (P = 0.021). The expression of Fra-1 was significantly reduced (P = 0.037) in SSc monocytes. Inhibiting AP-1 activity reduced TIMP-1 production in TLR-8-stimulated monocytes from healthy controls and SSc patients. ChIP experiments revealed binding of Fra-2 to the TIMP-1 promoter. Stimulation with DZNep plus TLR-8 enhanced Fra-2 and TIMP-1 expression in healthy control monocytes, whereas TLR-8 plus apicidin repressed Fra-2 and TIMP-1 expression. Finally, healthy control monocytes treated with DZNep plus TLR-8 induced strong production of α-smooth muscle actin in dermal fibroblasts, which was inhibited by TIMP-1-blocking antibody.

CONCLUSION

These data demonstrate a novel role of histone demethylation induced by DZNep on Fra-2-mediated TIMP-1 production by monocytes in the presence of TLR-8 agonist. This consequently orchestrates the transdifferentiation of fibroblasts, a key event in the pathogenesis of SSc.

Mechanisms of hepatic stellate cell activation

Hepatic fibrosis is a dynamic process characterized by the net accumulation of extracellular matrix resulting from chronic liver injury of any aetiology, including viral infection, alcoholic liver disease and NASH. Activation of hepatic stellate cells (HSCs) - transdifferentiation of quiescent, vitamin-A-storing cells into proliferative, fibrogenic myofibroblasts - is now well established as a central driver of fibrosis in experimental and human liver injury. Yet, the continued discovery of novel pathways and mediators, including autophagy, endoplasmic reticulum stress, oxidative stress, retinol and cholesterol metabolism, epigenetics and receptor-mediated signals, reveals the complexity of HSC activation. Extracellular signals from resident and inflammatory cells including macrophages, hepatocytes, liver sinusoidal endothelial cells, natural killer cells, natural killer T cells, platelets and B cells further modulate HSC activation. Finally, pathways of HSC clearance have been greatly clarified, and include apoptosis, senescence and reversion to an inactivated state. Collectively, these findings reinforce the remarkable complexity and plasticity of HSC activation, and underscore the value of clarifying its regulation in hopes of advancing the development of novel diagnostics and therapies for liver disease.

Indoleamine 2,3-dioxygenase 1 deficiency attenuates CCl4-induced fibrosis through Th17 cells down-regulation and tryptophan 2,3-dioxygenase compensation

Indoleamine 2,3-dioxygenase 1 (IDO1) is an intracellular rate-limiting enzyme in the metabolism of tryptophan along the kynurenine pathway, subsequently mediating the immune response; however, the role of IDO1 in liver fibrosis and cirrhosis is still unclear. In this study, we investigated the role of IDO1 in the development of hepatic fibrosis and cirrhosis. Patients with hepatitis B virus-induced cirrhosis and healthy volunteers were enrolled. For animals, carbon tetrachloride (CCl4) was used to establish liver fibrosis in wild-type and IDO1 knockout mice. Additionally, an IDO1 inhibitor (1-methyl-D-tryptophan) was administered to WT fibrosis mice. Liver lesions were positively correlated with serum IDO1 levels in both the clinical subjects and hepatic fibrosis mice. A positive correlation between serum IDO1 levels and liver stiffness values was found in the cirrhosis patients. Notably, IDO1 knockout mice were protected from CCl4-induced liver fibrosis, as reflected by unchanged serum alanine transaminase and aspartate transaminase levels and lower collagen deposition, α-smooth muscle actin expression and apoptotic cell death rates. On the other hand, tryptophan 2,3-dioxygenase (TDO), another systemic tryptophan metabolism enzyme, exhibited a compensatory increase as a result of IDO1 deficiency. Moreover, hepatic interleukin-17a, a characteristic cytokine of T helper 17 (Th17) cells, and downstream cytokines' mRNA levels showed lower expression in the IDO1-/- model mice. IDO1 appears to be a potential hallmark of liver lesions, and its deficiency protects mice from CCl4-induced fibrosis mediated by Th17 cells down-regulation and TDO compensation.

Targeting hepatic macrophages to treat liver diseases

Our view on liver macrophages in the context of health and disease has been reformed by the recognition of a remarkable heterogeneity of phagocytes in the liver. Liver macrophages consist of ontogenically distinct populations termed Kupffer cells and monocyte-derived macrophages. Kupffer cells are self-renewing, resident and principally non-migratory phagocytes, serving as sentinels for liver homeostasis. Liver injury triggers Kupffer cell activation, leading to inflammatory cytokine and chemokine release. This fosters the infiltration of monocytes into the liver, which give rise to large numbers of inflammatory monocyte-derived macrophages. Liver macrophages are very plastic and adapt their phenotype according to signals derived from the hepatic microenvironment (e.g. danger signals, fatty acids, phagocytosis of cellular debris), which explains their manifold and even opposing functions during disease. These central functions include the perpetuation of inflammation and hepatocyte injury, activation of hepatic stellate cells with subsequent fibrogenesis, and support of tumor development by angiogenesis and T cell suppression. If liver injury ceases, specific molecular signals trigger hepatic macrophages to switch their phenotype towards reparative phagocytes that promote tissue repair and regression of fibrosis. Novel strategies to treat liver disease aim at targeting macrophages. These interventions modulate Kupffer cell activation (e.g. via gut-liver axis or inflammasome formation), monocyte recruitment (e.g. via inhibiting chemokine pathways like CCR2 or CCL2) or macrophage polarization and differentiation (e.g. by nanoparticles). Evidence from mouse models and early clinical studies in patients with non-alcoholic steatohepatitis and fibrosis support the notion that pathogenic macrophage subsets can be successfully translated into novel treatment options for patients with liver disease.

LAY SUMMARY

Macrophages (Greek for "big eaters") are a frequent non-parenchymal cell type of the liver that ensures homeostasis, antimicrobial defense and proper metabolism. However, liver macrophages consist of different subtypes regarding their ontogeny (developmental origin), differentiation and function. Understanding this heterogeneity and the critical regulation of inflammation, fibrosis and cancer by macrophage subsets opens promising new options for treating liver diseases.

Hepatic anti-inflammatory effect of hexane extracts of Dioscorea batatas Decne: Possible suppression of toll-like receptor 4-mediated signaling

The hepatic anti-inflammatory potential of hexane extracts of Dioscorea batatas Decne edible part (EDH-1e) and bark (EDH-2b) were investigated in Western-type diet-fed apolipoprotein E null [ApoE (-/-)] mice and HepG2 cells. EDH-1e and EDH-2b suppressed the increased levels of tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, transforming growth factor beta 1 (TGF-β1), vascular cell adhesion protein 1 (VCAM-1), and monocyte chemoattractant protein-1 (MCP-1), and reduced infiltration of monocytes into liver tissue. The protein levels of Toll-like receptor 4 (TLR4) were also downregulated by EDH-1e and EDH-2b treatment as were the levels of activator protein 1 (AP-1), c-fos, and c-jun in the livers from Western-type diet-fed ApoE (-/-) mice and in lipopolysaccharide-stimulated HepG2 cells. Taken together, EDH-1e and EDH-2b attenuated hepatic inflammation and fibrosis via suppression of the TLR4-AP1-mediated signaling pathway.

肝脏巨噬细胞及其在肝损伤中的作用

肝脏巨噬细胞来源和功能复杂, 包括肝脏固有巨噬细胞和单核细胞来源的浸润巨噬细胞, 在宿主防御机制及维持机体内环境稳定中起着重要作用, 也是参与肝脏损伤和修复的主要细胞成分. 解析不同来源肝脏巨噬细胞在不同病因导致肝损伤过程中表型分化、生物学作用的动态变化及其分子机制, 对理解肝损伤的病理过程, 探索以肝脏巨噬细胞为靶点预防和治疗肝损伤以及肝纤维化的方案具有重要意义.

Emerging pharmacologic therapies for primary sclerosing cholangitis

PURPOSE OF REVIEW

The only currently approved treatment for primary sclerosing cholangitis (PSC) is liver transplantation, with a median time to transplant of 12-18 years after diagnosis. There are a number of emerging drugs that have the potential to meet this critically unmet need that will be summarized and discussed herein.

RECENT FINDINGS

Although the cause of PSC is unknown, there are a number of novel therapeutics under development. These drugs target presumed pathogenic mechanisms largely extrapolated from ex-vivo and in-vivo preclinical models, as well as translational observations.

SUMMARY

Future therapeutic strategies for PSC may include a multitude of complex pathogenic mechanisms encompassing pathways of immunomodulation, the microbiome and inflammation-related fibrosis.

The therapeutic landscape of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by lobular inflammation and hepatocellular ballooning, and may be associated with liver fibrosis leading to cirrhosis and its complications. A pharmacological approach is necessary to treat NASH because of failure to change dietary habits and lifestyle in most patients. Insulin resistance with an increased release of free fatty acids, oxidative stress and activation of inflammatory cytokines seem to be key features for disease progression. Thiazolidinediones, such as pioglitazone and antioxidant agents, such as vitamin E, were the first pharmacological options to be evaluated for NASH. In recent years, several new molecules that target different pathways related to NASH pathogenesis, such as liver metabolic homeostasis, inflammation, oxidative stress and fibrosis, have been developed. Obeticholic acid (INT-747) and elafibranor (GFT-505) have provided promising results in phase IIb, randomized, placebo-controlled clinical trials and they are being evaluated in ongoing phase III studies. Most of the potential treatments for NASH are under investigation in phase II studies, with some at phase I. This diversity in possible treatments calls for a better understanding of NASH in order to enrich trial populations with patients more susceptible to progress and to respond. This manuscript aims to review the pharmacological NASH treatment landscape.

Nonalcoholic Fatty Liver Disease and Insulin Resistance: New Insights and Potential New Treatments

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver disorders worldwide. It is associated with clinical states such as obesity, insulin resistance, and type 2 diabetes, and covers a wide range of liver changes, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH), liver cirrhosis, and hepatocellular carcinoma. Metabolic disorders, such as lipid accumulation, insulin resistance, and inflammation, have been implicated in the pathogenesis of NAFLD, but the underlying mechanisms, including those that drive disease progression, are not fully understood. Both innate and recruited immune cells mediate the development of insulin resistance and NASH. Therefore, modifying the polarization of resident and recruited macrophage/Kupffer cells is expected to lead to new therapeutic strategies in NAFLD. Oxidative stress is also pivotal for the progression of NASH, which has generated interest in carotenoids as potent micronutrient antioxidants in the treatment of NAFLD. In addition to their antioxidative function, carotenoids regulate macrophage/Kupffer cell polarization and thereby prevent NASH progression. In this review, we summarize the molecular mechanisms involved in the pathogenesis of NAFLD, including macrophage/Kupffer cell polarization, and disturbed hepatic function in NAFLD. We also discuss dietary antioxidants, such as β-cryptoxanthin and astaxanthin, that may be effective in the prevention or treatment of NAFLD.

NOX4 Regulates CCR2 and CCL2 mRNA Stability in Alcoholic Liver Disease

Recruitment of inflammatory cells is a major feature of alcoholic liver injury however; the signals and cellular sources regulating this are not well defined. C-C chemokine receptor type 2 (CCR2) is expressed by active hepatic stellate cells (HSC) and is a key monocyte recruitment signal. Activated HSC are also important sources of hydrogen peroxide resulting from the activation of NADPH oxidase 4 (NOX4). As the role of this NOX in early alcoholic liver injury has not been addressed, we studied NOX4-mediated regulation of CCR2/CCL2 mRNA stability. NOX4 mRNA was significantly induced in patients with alcoholic liver injury, and was co-localized with αSMA-expressing activated HSC. We generated HSC-specific NOX4 KO mice and these were pair-fed on alcohol diet. Lipid peroxidation have not changed significantly however, the expression of CCR2, CCL2, Ly6C, TNFα, and IL-6 was significantly reduced in NOX4^HSCKO compared to fl/fl mice. NOX4 promoter was induced in HSC by acetaldehyde treatment, and NOX4 has significantly increased mRNA half-life of CCR2 and CCL2 in conjunction with Ser221 phosphorylation and cytoplasmic shuttling of HuR. In conclusion, NOX4 is induced in early alcoholic liver injury and regulates CCR2/CCL2 mRNA stability thereby promoting recruitment of inflammatory cells and production of proinflammatory cytokines.

Perspectives on Nonalcoholic Fatty Liver Disease: An Overview of Present and Future Therapies

Nonalcoholic fatty liver disease (NAFLD) represents a major public health epidemic. Pharmacologic therapies for this condition are scarce, but multiple agents with novel mechanisms of action are in development. Here we review the pathophysiology and natural history of NALFD, diagnostic testing and data for currently available treatment strategies. We then turn our attention to promising developmental drugs and their respective trials. As the prevalence of fatty liver disease increases, clinicians will have more tools at hand for management of this condition. We conclude the horizon is bright for patients and doctors who deal with NAFLD.

Bile acids initiate cholestatic liver injury by triggering a hepatocyte-specific inflammatory response

Mechanisms of bile acid-induced (BA-induced) liver injury in cholestasis are controversial, limiting development of new therapies. We examined how BAs initiate liver injury using isolated liver cells from humans and mice and in-vivo mouse models. At pathophysiologic concentrations, BAs induced proinflammatory cytokine expression in mouse and human hepatocytes, but not in nonparenchymal cells or cholangiocytes. These hepatocyte-specific cytokines stimulated neutrophil chemotaxis. Inflammatory injury was mitigated in Ccl2^-/- mice treated with BA or after bile duct ligation, where less hepatic infiltration of neutrophils was detected. Neutrophils in periportal areas of livers from cholestatic patients also correlated with elevations in their serum aminotransferases. This liver-specific inflammatory response required BA entry into hepatocytes via basolateral transporter Ntcp. Pathophysiologic levels of BAs induced markers of ER stress and mitochondrial damage in mouse hepatocytes. Chemokine induction by BAs was reduced in hepatocytes from Tlr9^-/- mice, while liver injury was diminished both in conventional and hepatocyte-specific Tlr9^-/- mice, confirming a role for Tlr9 in BA-induced liver injury. These findings reveal potentially novel mechanisms whereby BAs elicit a hepatocyte-specific cytokine-induced inflammatory liver injury that involves innate immunity and point to likely novel pathways for treating cholestatic liver disease.

Developmental origins of NAFLD: a womb with a clue

Changes in the maternal environment leading to an altered intrauterine milieu can result in subtle insults to the fetus, promoting increased lifetime disease risk and/or disease acceleration in childhood and later in life. Particularly worrisome is that the prevalence of NAFLD is rapidly increasing among children and adults, and is being diagnosed at increasingly younger ages, pointing towards an early-life origin. A wealth of evidence, in humans and non-human primates, suggests that maternal nutrition affects the placenta and fetal tissues, leading to persistent changes in hepatic metabolism, mitochondrial function, the intestinal microbiota, liver macrophage activation and susceptibility to NASH postnatally. Deleterious exposures in utero include fetal hypoxia, increased nutrient supply, inflammation and altered gut microbiota that might produce metabolic clues, including fatty acids, metabolites, endotoxins, bile acids and cytokines, which prime the infant liver for NAFLD in a persistent manner and increase susceptibility to NASH. Mechanistic links to early disease pathways might involve shifts in lipid metabolism, mitochondrial dysfunction, pioneering gut microorganisms, macrophage programming and epigenetic changes that alter the liver microenvironment, favouring liver injury. In this Review, we discuss how maternal, fetal, neonatal and infant exposures provide developmental clues and mechanisms to help explain NAFLD acceleration and increased disease prevalence. Mechanisms identified in clinical and preclinical models suggest important opportunities for prevention and intervention that could slow down the growing epidemic of NAFLD in the next generation.

Liver inflammation and fibrosis

Chronic liver inflammation leads to fibrosis and cirrhosis, which is the 12th leading cause of death in the United States. Hepatocyte steatosis is a component of metabolic syndrome and insulin resistance. Hepatic steatosis may be benign or progress to hepatocyte injury and the initiation of inflammation, which activates immune cells. While Kupffer cells are the resident macrophage in the liver, inflammatory cells such as infiltrating macrophages, T lymphocytes, neutrophils, and DCs all contribute to liver inflammation. The inflammatory cells activate hepatic stellate cells, which are the major source of myofibroblasts in the liver. Here we review the initiation of inflammation in the liver, the liver inflammatory cells, and their crosstalk with myofibroblasts.

Antifibrotics in chronic liver disease: tractable targets and translational challenges

Chronic liver disease prevalence is increasing globally. Iterative liver damage, secondary to any cause of liver injury, results in progressive fibrosis, disrupted hepatic architecture, and aberrant regeneration, which are defining characteristics of liver cirrhosis. Liver transplantation is an effective treatment for end-stage liver disease; however, demand greatly outweighs donor organ supply, and in many parts of the world liver transplantation is unavailable. Hence, effective antifibrotic therapies are urgently required. In the past decade, rapid progress has been made in our understanding of the pathophysiology of liver fibrosis and a large number of potential cellular and molecular antifibrotic targets have been identified. This has led to numerous clinical trials of antifibrotic agents in patients with chronic liver disease. However, none of these have resulted in a robust and reproducible effect on fibrosis. It is therefore imperative that the ongoing translational challenges are addressed, to convert scientific discoveries into potent antifibrotics and enable bridging of the translational gap between putative therapeutic targets and effective treatments for patients with chronic liver disease.

Clinical Advancements in the Targeted Therapies against Liver Fibrosis

Hepatic fibrosis, characterized by excessive accumulation of extracellular matrix (ECM) proteins leading to liver dysfunction, is a growing cause of mortality worldwide. Hepatocellular damage owing to liver injury leads to the release of profibrotic factors from infiltrating inflammatory cells that results in the activation of hepatic stellate cells (HSCs). Upon activation, HSCs undergo characteristic morphological and functional changes and are transformed into proliferative and contractile ECM-producing myofibroblasts. Over recent years, a number of therapeutic strategies have been developed to inhibit hepatocyte apoptosis, inflammatory responses, and HSCs proliferation and activation. Preclinical studies have yielded numerous targets for the development of antifibrotic therapies, some of which have entered clinical trials and showed improved therapeutic efficacy and desirable safety profiles. Furthermore, advancements have been made in the development of noninvasive markers and techniques for the accurate disease assessment and therapy responses. Here, we focus on the clinical developments attained in the field of targeted antifibrotics for the treatment of liver fibrosis, for example, small molecule drugs, antibodies, and targeted drug conjugate. We further briefly highlight different noninvasive diagnostic technologies and will provide an overview about different therapeutic targets, clinical trials, endpoints, and translational efforts that have been made to halt or reverse the progression of liver fibrosis.

Murine macrophage response from peritoneal cavity requires signals mediated by chemokine receptor CCR-2 during Staphylococcus aureus infection

C-C chemokine receptor-2 (CCR-2) is a cognate receptor for monocyte chemotactic protein-1 (MCP-1), and recent studies revealed that MCP-1-CCR-2 signaling is involved in several inflammatory diseases characterized by macrophage infiltration. Currently, there is no study on the involvement of CCR-2 in the killing of S. aureus by macrophages of Swiss albino mice, and its substantial role in host defense against S. aureus infection in murine macrophages is still unclear. Therefore, the present study was aimed to investigate the functional and interactive role of CCR-2 and MCP-1 in regulating peritoneal macrophage responses with respect to acute S. aureus infection. We found that phagocytosis of S. aureus can serve as an important stimulus for MCP-1 production by peritoneal macrophages, which is dependent directly or indirectly on cytokines, reactive oxygen species and nitric oxide. Neutralization of CCR-2 in macrophages leads to increased production of IL-10 and decreased production of IFN-γ and IL-6. In CCR-2 blocked macrophages, pretreatment with specific blocker of NF-κB or p38-MAPK causes elevation in MCP-1 level and subsequent downregulation of CCR-2 itself. We speculate that CCR-2 is involved in S. aureus-induced MCP-1 production via NF-κB or p38-MAPK signaling. We also hypothesized that unnaturally high level of MCP-1 that build up upon CCR-2 neutralization might allow promiscuous binding to one or more other chemokine receptors, a situation that would not occur in CCR-2 non-neutralized condition. This may be the plausible explanation for such observed Th-2 response in CCR-2 blocked macrophages infected with S. aureus in the present study.

Infiltrating monocytes in liver injury and repair

Noninfectious liver injury causes many acute and chronic liver diseases around the globe, and particularly in developed nations. Bone marrow-derived monocytes infiltrate the damaged liver tissue and are a critical component of the innate immune response that may drive injury resolution or host death in the short term or chronic inflammation, fibrosis and hepatocellular carcinoma in the long term. Monocytes often play dual roles in liver injury—both perpetuating inflammation and promoting resolution of inflammation and fibrosis. Thus, we will address the role that monocytes play in different experimental forms of noninfectious liver injury; considering in particular the importance of the transition from inflammatory Ly6C^hi monocytes to pro-resolution Ly6C^lo monocyte-derived macrophages and the consequences of this transition for disease progression and resolution.

Role of inflammatory macrophages and CCR9/CCL25 chemokine axis in the pathogenesis of liver injury as a therapeutic target

It is widely known that a variety of immune cells in the liver contribute to the pathogenesis of liver diseases. Recently, roles of chemokines/chemokines receptors axes regarding the migration of immune competent cells to the inflamed liver have been reported as possible therapeutic targets. We here showed that CCR9⁺ CD11b⁺ macrophages play an important role during the course of Concanavalin A-induced murine acute liver injury as well as human acute hepatitis via the production of inflammatory cytokines and the Th1 induction. Further analysis using liver-shielded radiation and bone marrow (BM) transplantation model mice revealed that these CCR9⁺ CD11b⁺ macrophages are originated from BM-derived monocytes, but not liver resident macrophages (Kupffer cells). Furthermore, these CD11b⁺ inflammatory macrophages in contact with hepatic stellate cells contribute to the pathogenesis of murine experimental liver fibrosis via CCR9/CCL25 axis. Collectively, these results with further verification in human samples clarify the pathogenic role of CCR9/CCL25 axis as therapeutic target of a variety of liver diseases.

Targeting Hepatic Fibrosis in Autoimmune Hepatitis

Hepatic fibrosis develops or progresses in 25 % of patients with autoimmune hepatitis despite corticosteroid therapy. Current management regimens lack reliable noninvasive methods to assess changes in hepatic fibrosis and interventions that disrupt fibrotic pathways. The goals of this review are to indicate promising noninvasive methods to monitor hepatic fibrosis in autoimmune hepatitis and identify anti-fibrotic interventions that warrant evaluation. Laboratory methods can differentiate cirrhosis from non-cirrhosis, but their accuracy in distinguishing changes in histological stage is uncertain. Radiological methods include transient elastography, acoustic radiation force impulse imaging, and magnetic resonance elastography. Methods based on ultrasonography are comparable in detecting advanced fibrosis and cirrhosis, but their performances may be compromised by hepatic inflammation and obesity. Magnetic resonance elastography has excellent performance parameters for all histological stages in diverse liver diseases, is uninfluenced by inflammatory activity or body habitus, has been superior to other radiological methods in nonalcoholic fatty liver disease, and may emerge as the preferred instrument to evaluate fibrosis in autoimmune hepatitis. Promising anti-fibrotic interventions are site- and organelle-specific agents, especially inhibitors of nicotinamide adenine dinucleotide phosphate oxidases, transforming growth factor beta, inducible nitric oxide synthase, lysyl oxidases, and C-C chemokine receptors types 2 and 5. Autoimmune hepatitis has a pro-fibrotic propensity, and noninvasive radiological methods, especially magnetic resonance elastography, and site- and organelle-specific interventions, especially selective antioxidants and inhibitors of collagen cross-linkage, may emerge to strengthen current management strategies.

Bone marrow-derived macrophages distinct from tissue-resident macrophages play a pivotal role in Concanavalin A-induced murine liver injury via CCR9 axis

The fundamental mechanism how heterogeneous hepatic macrophage (Mφ) subsets fulfill diverse functions in health and disease has not been elucidated. We recently reported that CCR9⁺ inflammatory Mφs play a critical role in the course of acute liver injury. To clarify the origin and differentiation of CCR9⁺Mφs, we used a unique partial bone marrow (BM) chimera model with liver shielding for maintaining hepatic resident Mφs. First, irradiated mice developed less liver injury with less Mφs accumulation by Concanavalin A (Con A) regardless of liver shielding. In mice receiving further BM transplantation, CD11b^lowF4/80^high hepatic-resident Mφs were not replaced by transplanted donors under steady state, while under inflammatory state by Con A, CCR9⁺Mφs were firmly replaced by donors, indicating that CCR9⁺Mφs originate from BM, but not from hepatic-resident cells. Regarding the mechanism of differentiation and proliferation, EdU⁺CCR9⁺Mφs with a proliferative potential were detected specifically in the inflamed liver, and in vitro study revealed that BM-derived CD11b⁺ cells co-cultured with hepatic stellate cells (HSCs) or stimulated with retinoic acids could acquire CCR9 with antigen-presenting ability. Collectively, our study demonstrates that inflammatory Mφs originate from BM and became locally differentiated and proliferated by interaction with HSCs via CCR9 axis during acute liver injury.

FXR agonist obeticholic acid reduces hepatic inflammation and fibrosis in a rat model of toxic cirrhosis

Hepatic inflammation drives hepatic stellate cells (HSC), resulting in liver fibrosis. The Farnesoid-X receptor (FXR) antagonizes inflammation through NF-κB inhibition. We investigated preventive and therapeutic effects of FXR agonist obeticholic acid (OCA) on hepatic inflammation and fibrosis in toxic cirrhotic rats. Cirrhosis was induced by thioacetamide (TAA) intoxication. OCA was given during or after intoxication with vehicle-treated rats as controls. At sacrifice, fibrosis, hemodynamic and biochemical parameters were assessed. HSC activation, cell turn-over, hepatic NF-κB activation, pro-inflammatory and pro-fibrotic cytokines were determined. The effect of OCA was further evaluated in isolated HSC, Kupffer cells, hepatocytes and liver sinusoidal endothelial cells (LSEC). OCA decreased hepatic inflammation and fibrogenesis during TAA-administration and reversed fibrosis in established cirrhosis. Portal pressure decreased through reduced intrahepatic vascular resistance. This was paralleled by decreased expression of pro-fibrotic cytokines (transforming growth-factor β, connective tissue growth factor, platelet-derived growth factor β-receptor) as well as markers of hepatic cell turn-over, by blunting effects of pro-inflammatory cytokines (e.g. monocyte chemo-attractant protein-1). In vitro, OCA inhibited both LSEC and Kupffer cell activation; while HSC remained unaffected. This related to NF-κB inhibition via up-regulated IκBα. In conclusion, OCA inhibits hepatic inflammation in toxic cirrhotic rats resulting in decreased HSC activation and fibrosis.

Micronutrient Antioxidants and Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most important chronic liver diseases worldwide and has garnered increasing attention in recent decades. NAFLD is characterized by a wide range of liver changes, from simple steatosis to nonalcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma. The blurred pathogenesis of NAFLD is very complicated and involves lipid accumulation, insulin resistance, inflammation, and fibrogenesis. NAFLD is closely associated with complications such as obesity, diabetes, steatohepatitis, and liver fibrosis. During the progression of NAFLD, reactive oxygen species (ROS) are activated and induce oxidative stress. Recent attempts at establishing effective NAFLD therapy have identified potential micronutrient antioxidants that may reduce the accumulation of ROS and finally ameliorate the disease. In this review, we present the molecular mechanisms involved in the pathogenesis of NAFLD and introduce some dietary antioxidants that may be used to prevent or cure NAFLD, such as vitamin D, E, and astaxanthin.

Human Menstrual Blood-Derived Stem Cells Ameliorate Liver Fibrosis in Mice by Targeting Hepatic Stellate Cells via Paracrine Mediators

Mesenchymal stem cells (MSCs) may have potential applications in regenerative medicine for the treatment of chronic liver diseases (CLDs). Human menstrual blood is a novel source of MSCs, termed menstrual blood-derived stem cells (MenSCs). Compared with bone marrow MSCs, MenSCs exhibit a higher proliferation rate and they can be obtained through a simple, safe, painless procedure without ethical concerns. Although the therapeutic efficacy of MenSCs has been explored in some diseases, their effects on liver fibrosis are still unclear. In the present study, we investigated the therapeutic effects of MenSC transplantation in a carbon tetrachloride-induced mouse model of liver fibrosis. These results revealed that MenSCs markedly improved liver function, attenuated collagen deposition, and inhibited activated hepatic stellate cells up to 2 weeks after transplantation. Moreover, tracking of green fluorescent protein-expressing MenSCs demonstrated that transplanted cells migrated to the sites of injury, but few differentiated into functional hepatocyte-like cells. Transwell coculturing experiments also showed that MenSCs suppressed proliferation of LX-2 cells (an immortalized hepatic stellate cell line) through secretion of monocyte chemoattractant protein-1, interleukin-6, hepatocyte growth factor, growth-related oncogene, interleukin-8, and osteoprotegerin. Collectively, our results provided preliminary evidence for the antifibrotic capacity of MenSCs in liver fibrosis and suggested that these cells may be an alternative therapeutic approach for the treatment of CLDs. Stem Cells Translational Medicine 2017;6:272-284.

Evaluation of urinary bladder fibrogenesis in a mouse model of long-term ketamine injection

Long-term ketamine abuse has been shown to affect the lower urinary tract and result in interstitial cystitis-like syndrome. However, the causative mechanism of ketamine-induced dysfunction remains unclear. The present study aimed to investigate the physiological, histological and molecular changes on ketamine-associated cystitis (KC) in a mouse model. Both male and female Balb/c mice were separately distributed into the control group (normal saline) and ketamine group, which received ketamine hydrochloride (100 mg/kg/day) daily by intraperitoneal injection for a total period of 20 weeks. In each group, the urine was analyzed by gas chromatography-mass spectrometry to measure the concentration of ketamine and its metabolites. Urinary frequency and urine volume were examined to investigate the urinary voiding functions. Mice bladders were excised for cDNA microarray and hematoxylin and eosin (HE) staining. The ketamine and metabolites were detected only in ketamine-treated mice urine. The voiding interval was reduced in the male mice group after 20 week ketamine administration. Additionally, the result of cDNA array analysis revealed a number of gene expression levels involved in chronic wound healing response and collagen accumulation, which were closely associated with fibrosis progression in the connective tissue. In HE staining of the bladder tissue, the ketamine-injected mice exhibited prominently denser blood vessel distribution in the submucosal layer. Based on the evidence in the present study, a mechanism that delineates fibrosis formation of urinary bladder induced by the pathogenesis of ketamine abuse can be constructed.

Urine Monocyte Chemoattractant Protein-1 Is an Independent Predictive Factor of Hospital Readmission and Survival in Cirrhosis

MCP-1 (monocyte chemoattractant protein-1) is a proinflammatory cytokine involved in chemotaxis of monocytes. In several diseases, such as acute coronary syndromes and heart failure, elevated MCP-1 levels have been associated with poor outcomes. Little is known about MCP-1 in cirrhosis.

AIM

To investigate the relationship between MCP-1 and outcome in decompensated cirrhosis.

METHODS

Prospective study of 218 patients discharged from hospital after an admission for complications of cirrhosis. Urine and plasma levels of MCP-1 and other urine proinflammatroy biomarkers: osteopontin(OPN), trefoil-factor3 and liver-fatty-acid-binding protein were measured at admission. Urine non-inflammatory mediators cystatin-C, β2microglobulin and albumin were measured as control biomarkers. The relationship between these biomarkers and the 3-month hospital readmission, complications of cirrhosis, and mortality were assessed.

RESULTS

69 patients(32%) had at least one readmission during the 3-month period of follow-up and 30 patients died(14%). Urine MCP-1 and OPN levels, were associated with 3-month probability of readmission (0.85 (0.27-2.1) and 2003 (705-4586) ug/g creat vs 0.47 (0.2-1.1) and 1188 (512-2958) ug/g creat, in patients with and without readmission, respectively; p<0.05; median (IQR)). Furthermore, urine levels of MCP-1 were significantly associated with mortality (1.01 (1-3.6) vs 0.5 (0.2-1.1) μg/g creat, in dead and alive patients at 3 months; p<0.05). Patients with higher levels of urine MCP-1 (above percentile 75th) had higher probability of development of hepatic encephalopathy, bacterial infections or AKI. Urine MCP-1 was an independent predictive factor of hospital readmission and combined end-point of readmission or dead at 3 months. Plasma levels of MCP-1 did not correlated with outcomes.

CONCLUSION

Urine, but not plasma, MCP-1 levels are associated with hospital readmission, development of complications of cirrhosis, and mortality. These results suggest that in cirrhosis there is an inflammatory response that is associated with poor outcomes.