Nogo-B: A potential indicator for hepatic cirrhosis and regulator in hepatic stellate cell activation

Endothelial Nogo-B Suppresses Cancer Cell Proliferation via a Paracrine TGF-β/Smad Signaling

Nogo-B has been reported to play a critical role in angiogenesis and the repair of damaged blood vessels; however, its role in the tumor microenvironment remains unclear. Here, we observed the differential expression of Nogo-B in endothelial cells from hepatocellular carcinoma (HCC) and glioma samples. Downregulation of Nogo-B expression correlated with the malignant phenotype of cancer and a poor prognosis for patients. In subsequent studies, endothelial Nogo-B inhibition robustly promoted the growth of HCC or glioma xenografts in nude mice. Intriguingly, endothelial Nogo-B silencing dramatically suppressed endothelial cell expansion and tumor angiogenesis, but potently enhanced the proliferation of neighboring HCC and glioma cells. Based on the results of the ELISA assay, Nogo-B silencing reduced TGF-β production in endothelial cells, which attenuated the phosphorylation and nuclear translocation of Smad in neighboring cancer cells. The endothelial Nogo-B silencing-mediated increase in cancer cell proliferation was abolished by either a TGF-β neutralizing antibody or TGF-β receptor inhibitor, indicating the essential role for TGF-β in endothelial Nogo-B-mediated suppression of cancer growth. These findings not only broaden our understanding of the crosstalk between cancer cells and endothelial cells but also provide a novel prognostic biomarker and a therapeutic target for cancer treatments.

The regulatory role and mechanism of autophagy in energy metabolism-related hepatic fibrosis

Hepatic fibrosis is a key pathological process of chronic liver diseases, caused by alcohol, toxic and aberrant energy metabolism. It progresses to cirrhosis or even hepatic carcinoma without effective treatment. Studies have shown that autophagy has important regulatory effects on hepatic stellate cells (HSCs) energy metabolism, and then affect the activation state of HSCs. Autophagy maintains hepatic energy homeostasis, and the dysregulation of autophagy can lead to the activation of HSCs and the occurrence and development of hepatic fibrosis. It is necessary to explore the mechanism of autophagy in energy metabolism-related hepatic fibrosis. Herein, the current study summarizes the regulating mechanisms of autophagy through different targets and signal pathways in energy metabolism-related hepatic fibrosis, and discusses the regulatory effect of autophagy by natural plant-derived, endogenous and synthetic compounds for the treatment of hepatic fibrosis. A better comprehension of autophagy in hepatic stellate cells energy metabolism-related hepatic fibrosis may provide effective intervention of hepatic fibrosis, explore the potential clinical strategies and promote the drug treatment of hepatic fibrosis.

Transcriptome analysis reveals the molecular mechanism of Yiqi Rougan decoction in reducing CCl4-induced liver fibrosis in rats

Background

Liver fibrosis develops from various chronic liver diseases, and there is currently a lack of specific treatment strategies. Yiqi Rougan decoction (YQRG) is a traditional Chinese medicine that has shown durative effects in the treatment of liver fibrosis; however, the mechanism associated with YQRG-related improvements in liver fibrosis remains to be experimentally determined. This study evaluated the therapeutic effect of YQRG on carbon tetrachloride (CCl₄)-induced liver fibrosis in rats and its molecular mechanism.

Methods

We used low-, medium-, and high-dose YQRG to treat CCl₄-induced liver fibrosis in rats, followed by assessment of liver injury and fibrosis according to liver appearance, body weight, liver mass index, histopathologic examination, and serum testing. Additionally, we performed transcriptome analysis using RNA-sequencing (RNA-seq) technology, including cluster, Gene Ontology (GO), and pathway analyses, to identify differentially expressed genes (DEGs), and protein and gene expression were detected by immunofluorescence (IFC), western blot and real-time quantitative PCR.

Results

The results showed that YQRG effectively alleviated CCl₄-induced liver injury and fibrosis in rats, including observations of improved liver function, decreased activity of hepatic stellate cells (HSCs), and decreased extracellular matrix (ECM) deposition. Moreover, we identified downregulated and upregulated DEGs in the model group relative to the control and YQRG-treated groups, with GO analysis revealing their enrichment in biological processes, such as endoplasmic reticulum stress (ERS), apoptosis, and autophagy. Furthermore, pathway analysis showed that YQRG treatment downregulated the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase/Akt (PI3K/AKT) signalling pathways and upregulated other signalling pathways, including those related to peroxisome proliferator-activated receptors(PPAR) and AMP-activated protein kinase(AMPK), with these findings subsequently verified experimentally.

Conclusion

These findings showed that YQRG improved CCl₄-induced liver fibrosis through multiple mechanisms and pathways, offering critical insight into the YQRG-related therapeutic mechanism and promoting further research into its potential application.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00552-w.

Role of serum Nogo-B as a biomarker for diagnosis of chronic liver diseases and its severity

Background

Nogo-B is one of the members of the reticulon family. Nogo-B influences the proliferation of the hepatic stellate cells inducing liver fibrotic changes. We aimed at measuring the serum levels of Nogo-B in patients with chronic liver disease (CLD) with different etiologies. Ninety subjects were included, 18 of them were normal healthy individuals and 72 had liver disease (fibrosis/cirrhosis) with different etiologies: post-hepatitis C infection, post-hepatitis B infection, NASH, and autoimmune hepatitis. Serum Nogo-B was assessed using ELISA. Patients were subdivided according to the Child-Pugh score into 3 groups: group 1—Child A (24 patients); group 2—Child B (24 patients); and group 3—Child C (24 patients).

Results

Serum Nogo-B levels were found to be significantly higher in patients (1477.92 ± 1113.50) when compared with healthy control (301.28 ± 180.87) (p < 0.001). There was a statistically significant difference in serum Nogo-B level between the three sub-groups of patients (p < 0.001). A positive correlation was found between serum Nogo-B and MELD score (r = 0.46, p-value < 0.001). However, there was no correlation found between Nogo-B and FIB-4 index or APRI score. There was a significant positive correlation between serum Nogo-B level and coagulation profile and serum bilirubin. An inverse correlation was found between serum Nogo-B with serum albumin. A ROC curve was done to examine the validity of Nogo-B in the diagnosis of liver cirrhosis, and the area under the curve was found to be 0.979, a cutoff value of 600 with a sensitivity of 97.2% and a specificity of 94.4% (p-value < 0.001).

Conclusion

Nogo-B had a high value in the identification of patients with any severity of CLD. There is a highly significant correlation between Nogo-B and the synthetic function of the liver; it could be used as a measure of hepatic functional reserve.

Nogo-B promotes epithelial-mesenchymal transition in lung fibrosis via PERK branch of the endoplasmic reticulum stress pathway

Background

Idiopathic pulmonary fibrosis (IPF) is a fatal chronic pulmonary fibrosis disease and pathological mechanisms of fibrogenesis in IPF are still to be elucidated. Here, we investigated the potential role of Nogo-B in pulmonary fibrogenesis.

Methods

A mouse model of pulmonary fibrosis was established by intratracheal injection of bleomycin (BLM). Lung epithelial cells MLE-12 and TC-1 JHU-1 were cultured for TGF-β treatment. The extent of lung fibrosis was evaluated using hematoxylin and eosin (HE) staining and Masson staining in model mice and Nogo-B knockout mice. The protein levels of Nogo-B, endoplasmic reticulum stress (ERS) sensors including PERK, IRE1α, ATF6 and epithelial-mesenchymal transition (EMT) markers including E-cadherin and N-cadherin, vimentin were assayed by Western blotting respectively after Nogo-B knockdown or overexpression with lentivirus. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate cytokine levels of TGF-β, TNF-α, IL-1β, IL-6 and IL-10 in bronchoalveolar lavage fluid (BALF).

Results

Nogo-B expression was up-regulated in lung tissues of fibrosis model mice and alveolar epithelial cells. Nogo-B knockdown significantly attenuated lung fibrogenesis, downregulated the levels of inflammatory cytokines, inhibited EMT as well as decreased the level of phosphor-PERK/PERK but not the levels of phosphor-IRE1α/IRE1α and c-ATF6. Additionally, a potential efficacy of PERK blockade was demonstrated in improving the extent of lung fibrosis in model mice.

Conclusions

This study discovered that involvement of Nogo-B in pulmonary fibrogenesis was associated with the PERK branch of ERS pathway and EMT. Nogo-B could be considered as a potential therapeutic target for the treatment of IPF.

Rosiglitazone alleviates intrahepatic cholestasis induced by α-naphthylisothiocyanate in mice: The role of circulating 15-deoxy-Δ12,14 -PGJ2 and Nogo

BACKGROUND AND PURPOSE

Intrahepatic cholestasis is mainly caused by dysfunction of bile secretion and has limited effective treatment. Rosiglitazone is a synthetic agonist of PPARγ, whose endogenous agonist is 15-deoxy-Δ^12,14 -PGJ₂ (15d-PGJ₂ ). Reticulon 4B (Nogo-B) is the detectable Nogo protein family member in the liver and secreted into circulation. Here, we determined if rosiglitazone can alleviate intrahepatic cholestasis in mice.

EXPERIMENTAL APPROACH

Wild-type, hepatocyte-specific PPARγ or Nogo-B knockout mice received intragastric administration of α-naphthylisothiocyanate (ANIT) and/or rosiglitazone, followed by determination of intrahepatic cholestasis and the involved mechanisms. Serum samples from primary biliary cholangitis (PBC) patients and non-PBC controls were analysed for cholestasis-related parameters.

KEY RESULTS

Rosiglitazone prevented wild type, but not hepatocyte-specific PPARγ deficient mice from developing ANIT-induced intrahepatic cholestasis by increasing expression of bile homeostatic proteins, reducing hepatic necrosis, and correcting abnormal serum parameters and enterohepatic circulation of bile. Nogo-B knockout provided protection similar to that of rosiglitazone treatment. ANIT-induced intrahepatic cholestasis decreased 15d-PGJ₂ but increased Nogo-B in serum, and both were corrected by rosiglitazone. Nogo-B deficiency in the liver increased 15d-PGJ₂ production, thereby activating expression of PPARγ and bile homeostatic proteins. Rosiglitazone and Nogo-B deficiency also alleviated cholestasis-associated dyslipidemia. In addition, rosiglitazone reduced symptoms of established intrahepatic cholestasis in mice. In serum from PBC patients, the decreased 15d-PGJ₂ and increased Nogo-B levels were significantly correlated with classical cholestatic markers.

CONCLUSIONS AND IMPLICATIONS

Levels of 15d-PGJ₂ and Nogo are important biomarkers for intrahepatic cholestasis. Synthetic agonists of PPARγ could be used for treatment of intrahepatic cholestasis and cholestasis-associated dyslipidemia.

Identification of Nogo-B as a new molecular target of peroxisome proliferator-activated receptor gamma

Nonalcoholic fatty liver disease (NAFLD) is a fast-growing chronic liver disease worldwide which can lead to liver cirrhosis. Peroxisome proliferator-activated receptor γ (PPARγ), a ligand-activated transcription factor, plays an important role in lipogenesis. Increased Nogo-B expression can be determined in the liver of cirrhosis patients. However, the effect of PPARγ activation on hepatic Nogo-B expression remains unknown. In this study, we found PPARγ activation by rosiglitazone or dephosphorylation increased Nogo-B expression at mRNA and protein levels in HepG2 cells and mouse primary hepatocytes. Furthermore, we identified a PPARγ response element (PPRE) in Nogo-B promoter and found PPARγ enhanced Nogo-B transcription in a PPRE-dependent manner. ChIP assay further confirms rosiglitazone enhanced the binding of PPARγ to Nogo-B promoter. Using a liver specific PPARγ deficient mice, we determined the critical role of PPARγ expression in regulating hepatic Nogo-B expression. Increased glucose and palmitate in culture medium activated Nogo-B and PPARγ expression in mouse primary hepatocytes, and corresponding, high-fat diet (HFD) induced fatty liver associated with increased hepatic Nogo-B and PPARγ expression in mice. Similarly, serum Nogo-B levels in patients with NAFLD were increased. However, rosiglitazone treatment reduced HFD-induced fatty liver and Nogo-B expression. In summary, our study identifies Nogo-B as a new molecular target of PPARγ, and suggests increased Nogo-B might be a potential indicator for NAFLD.

ER-residential Nogo-B accelerates NAFLD-associated HCC mediated by metabolic reprogramming of oxLDL lipophagy

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome that elevates the risk of hepatocellular carcinoma (HCC). Although alteration of lipid metabolism has been increasingly recognized as a hallmark of cancer cells, the deregulated metabolic modulation of HCC cells in the NAFLD progression remains obscure. Here, we discovers an endoplasmic reticulum-residential protein, Nogo-B, as a highly expressed metabolic modulator in both murine and human NAFLD-associated HCCs, which accelerates high-fat, high-carbohydrate diet-induced metabolic dysfunction and tumorigenicity. Mechanistically, CD36-mediated oxLDL uptake triggers CEBPβ expression to directly upregulate Nogo-B, which interacts with ATG5 to promote lipophagy leading to lysophosphatidic acid-enhanced YAP oncogenic activity. This CD36-Nogo-B-YAP pathway consequently reprograms oxLDL metabolism and induces carcinogenetic signaling for NAFLD-associated HCCs. Targeting the Nogo-B pathway may represent a therapeutic strategy for HCC arising from the metabolic syndrome.

Plasma Nogo-A and placental growth factor levels are associated with portal hypertension in patients with liver cirrhosis

BACKGROUND

Clinically significant portal hypertension (CSPH) and severe portal hypertension (SPH) increase the risk for decompensation and life-threatening complications in liver cirrhosis. Pathologic angiogenesis might contribute to the formation of these conditions. Placental growth factor (PlGF) and Nogo-A protein are biomarkers of pathological angiogenesis, but data on their role in liver cirrhosis and portal hypertension is scarce.

AIM

To determine plasma levels of PlGF and Nogo-A in patients with liver cirrhosis, CSPH, SPH and potential to predict portal hypertension.

METHODS

A cohort of 122 patients with hepatitis C virus and/or alcohol-induced liver cirrhosis with characterized hepatic venous pressure gradient (HVPG) were included in the study. Demographic data, medical history, Child-Turcotte-Pugh and Model of End Stage liver disease score, clinical chemistry, liver stiffness values were recorded on the day of the procedure prior HVPG measurement. The degree of portal hypertension was determined by the invasive HVPG measurement. Nogo-A and PlGF plasma levels were evaluated using enzyme linked immunosorbent assay. The control group consisted of 30 healthy age- and sex- matched individuals.

RESULTS

Peripheral PlGF levels were higher and Nogo-A levels were lower in patients with liver cirrhosis (23.20 vs 9.85; P < 0.0001 and 2.19 vs 3.12; P = 0.004 respectively). There was a positive linear correlation between peripheral levels of PlGF and HVPG (r = 0.338, P = 0.001) and negative linear correlation between the peripheral Nogo-A levels and HVPG (r = -0.267, P = 0.007). PlGF levels were higher in CSPH and SPH (P = 0.006; P < 0.0001) whereas Nogo-A levels were lower (P = 0.01; P < 0.033). Area under the curve for the diagnosis of CSPH for PlGF was 0.68 (P = 0.003) and for Nogo-A - 0.67 (P = 0.01); for SPH 0.714 (P < 0.0001) and 0.65 (P = 0.014) respectively. PlGF levels were higher and Nogo-A levels were lower in patients with esophageal varices (P < 0.05). PlGF cut-off value of 25 pg/mL distinguished patients with CSPH at 55.7% sensitivity and 76.7% specificity; whereas Nogo-A cut-off value of 1.12 ng/mL was highly specific (93.1%) for the diagnosis of CSPH.

CONCLUSION

Plasma PlGF levels were higher while Nogo-A levels were lower in patients with liver cirrhosis and portal hypertension. Biomarkers showed moderate predictive value in determining CSPH and SPH.

Inhibition of Nogo-B promotes cardiac hypertrophy via endoplasmic reticulum stress

AIMS

Nogo-B is a key endoplasmic reticulum (ER) protein that regulates ER stress signaling. However, its role in cardiac hypertrophy remains poorly understood. ER stress is interrelated with autophagy in the process of cardiac hypertrophy. Therefore, we aimed to test the hypothesis that both ER stress and autophagy signaling mediate the function of Nogo-B in cardiac hypertrophy.

MAIN METHODS

Rat models of transverse aortic constriction (TAC), neonatal rat cardiomyocytes (NRCMs) stimulated with norepinephrine (Ne) and primary cardiac fibroblasts treated with transforming growth factor β1 (TGF-β1) were used in this study. The expression of Nogo-B and markers of ER stress were determined by quantitative RT-PCR, western blotting and immunofluorescence. Autophagy was measured by monitoring autophagic flux. Specific small interfering RNA (siRNA) of Nogo-B was transfected to investigate the role of Nogo-B in regulating cardiac hypertrophy.

KEY FINDINGS

In TAC-induced hypertrophic heart tissues, Ne-treated hypertrophic cardiomyocytes and TGF-β1-stimulated cardiac fibroblasts, the expression of Nogo-B, and markers of ER stress were significantly elevated. Impairment of autophagic flux was observed in the activated cardiac fibroblasts. Down-regulation of Nogo-B by siRNA further exacerbated Ne-induced cardiomyocyte hypertrophy and TGF-β1-induced cardiac fibroblast activation. Gene silencing of Nogo-B promoted the activation of the ER stress pathway and the impairment of autophagic flux. Moreover, inhibition of Nogo-B activated the protein kinase RNA-like ER kinase (PERK)/activating transcriptional factor 4 (ATF4) and activating transcriptional factor 6 (ATF6) branches of ER stress pathways.

SIGNIFICANCE

These findings suggest that inhibition of Nogo-B promotes cardiomyocyte hypertrophy and cardiac fibroblast activation by activating the PERK/ATF4 signaling pathway and defects of autophagic flux.

The role of novel cytokines in inflammation: Defining peripheral artery disease among patients with coronary artery disease

Coronary artery disease (CAD) patients with concomitant peripheral artery disease (PAD) experience more extensive and calcified atherosclerosis, greater lesion progression and more common coronary events compared to patients with CAD only. To characterize the distinct features of this aggressive atherosclerotic disease, we studied novel cytokines that code different stages of atherogenesis. One hundred and eighty consecutive subjects (60 patients into each group of CAD+PAD, CAD and controls) were recruited among patients with stable angina pectoris scheduled for coronary angiography. An ankle-brachial index (ABI) ≤0.9 was determined as occlusive PAD. Fasting serum tumor necrosis factor (TNF)-like antigen 1A (TL1A) and its receptor death receptor 3 (DR3), NOGO-B (reticulon 4B) and its receptor NUS1, high-sensitivity C-reactive protein (hsCRP), A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) 1, 4, 5 and interleukin (IL) 6 levels were determined. Serum hsCRP and DR3/TL1A concentrations were similar and higher than controls in the CAD and CAD+PAD groups. Levels of NOGO-B and its receptor NUS1 were increased and ADAMTS-5 was decreased in patients with CAD+PAD. Independent predictors of ABI in multivariate analysis were smoking (B = -0.13, p = 0.04), NUS1 (B = -0.88, p < 0.001), ADAMTS-5 (B = 0.63, p < 0.001) and SYNTAX score (B = -0.26, p < 0.001). Similarly, smoking (OR = 5.5, p = 0.019), SYNTAX score (OR = 1.2, p < 0.001), NUS1 (OR = 14.4, p < 0.001), ADAMTS-5 (OR = 1.1, p < 0.001) and age (OR = 1.1, p = 0.042) independently predicted the involvement of peripheral vasculature in logistic regression. The diagnostic performance of these cytokines to discriminate CAD+PAD were AUC 0.79 ( p < 0.001) for NUS1 and 0.37 ( p = 0.013) for ADAMTS-5. We report herein that circulating cytokines can give clues to the ongoing atherosclerotic process and the extent of vascular involvement in which distinct features of ADAMTS-5 and NUS1 make them promising cytokines for future research.

Hepatic stellate cells as key target in liver fibrosis

Progressive liver fibrosis, induced by chronic viral and metabolic disorders, leads to more than one million deaths annually via development of cirrhosis, although no antifibrotic therapy has been approved to date. Transdifferentiation (or "activation") of hepatic stellate cells is the major cellular source of matrix protein-secreting myofibroblasts, the major driver of liver fibrogenesis. Paracrine signals from injured epithelial cells, fibrotic tissue microenvironment, immune and systemic metabolic dysregulation, enteric dysbiosis, and hepatitis viral products can directly or indirectly induce stellate cell activation. Dysregulated intracellular signaling, epigenetic changes, and cellular stress response represent candidate targets to deactivate stellate cells by inducing reversion to inactivated state, cellular senescence, apoptosis, and/or clearance by immune cells. Cell type- and target-specific pharmacological intervention to therapeutically induce the deactivation will enable more effective and less toxic precision antifibrotic therapies.

An endoplasmic reticulum protein, Nogo-B, facilitates alcoholic liver disease through regulation of kupffer cell polarization

Nogo-B (Reticulon 4B) is an endoplasmic reticulum (ER) resident protein that regulates ER structure and function. Because ER stress is known to induce M2 macrophage polarization, we examined whether Nogo-B regulates M1/M2 polarization of Kupffer cells and alters the pathogenesis of alcoholic liver disease (ALD). M1 and M2 phenotypes were assessed in relation to Nogo-B expression and disease severity in liver specimens from ALD patients (NCT01875211). Liver specimens from wild-type (WT) and Nogo-B knockout (KO) mice fed a control or Lieber-DeCarli ethanol liquid diet (5% ethanol) for 6 weeks were analyzed for liver injury and steatosis. Kupffer cells isolated from WT and Nogo-B KO mice were assessed for M1 and M2 activation. A significant positive correlation was observed between Nogo-B positive Kupffer cells and disease severity in ALD patients (n = 30, r = 0.66, P = 0.048). Furthermore, Nogo-B-positive Kupffer cells were correlated with M1 activation (inducible nitric oxide synthase) (r = 0.50, P = 0.05) and negatively with markers of M2 status (CD163) (r = -0.48, P = 0.07) in these patients. WT mice exhibited significantly increased liver injury (P < 0.05) and higher hepatic triglyceride levels (P < 0.01) compared with Nogo-B KO mice in response to chronic ethanol feeding. Nogo-B in Kupffer cells promoted M1 polarization, whereas absence of Nogo-B increased ER stress and M2 polarization in Kupffer cells.

CONCLUSION

Nogo-B is permissive of M1 polarization of Kupffer cells, thereby accentuating liver injury in ALD in humans and mice. Nogo-B in Kupffer cells may represent a new therapeutic target for ALD. (Hepatology 2017;65:1720-1734).

Sustained HSP25 Expression Induces Clasmatodendrosis via ER Stress in the Rat Hippocampus

Heat shock protein (HSP) 25 (murine/rodent 25 kDa, human 27 kDa) is one of the major astroglial HSP families, which has a potent anti-apoptotic factor contributing to a higher resistance of astrocytes to the stressful condition. However, impaired removals of HSP25 decrease astroglial viability. In the present study, we investigated whether HSP25 is involved in astroglial apoptosis or clasmatodendrosis (autophagic astroglial death) in the rat hippocampus induced by status epilepticus (SE). Following SE, HSP25 expression was transiently increased in astrocytes within the dentate gyrus (DG), while it was sustained in CA1 astrocytes until 4 weeks after SE. HSP25 knockdown exacerbated SE-induced apoptotic astroglial degeneration, but mitigated clasmatodendrosis accompanied by abrogation of endoplasmic reticulum (ER) stress without changed seizure susceptibility or severity. These findings suggest that sustained HSP25 induction itself may result in clasmatodendrosis via prolonged ER stress. To the best of our knowledge, the present study demonstrates for the first time the double-edge properties of HSP25 in astroglial death induced by SE.

MircoRNA-145 promotes activation of hepatic stellate cells via targeting krüppel-like factor 4

Krüppel-like Factor 4 (KLF4), a target gene of miR-145, can negatively regulate lung fibrosis. However, the potential role of KLF4 and miR-145 in hepatic stellate cells (HSCs) activation or in hepatic fibrosis keeps unclear. This study aims to characterize miR-145 and KLF4 in activated HSCs and liver cirrhotic, and the underlying molecular basis. miR-145 was significantly up-regulated, while KLF4 was dramatically down-regulated during the activation of rat primary HSCs and TGF-βtreated HSCs. Furthermore, miR-145 mimics induced and inhibition of miR-145 reduced α-SMA and COL-I expression in primary HSCs. Additionally, the mRNA and protein levels of KLF4 in the liver of cirrhotic patients and rats were significantly down-regulated. α-SMA and COL-I were increased after inhibition of KLF4 by specific shRNA in primary HSCs. Forced KLF4 expression led to a reduction of α-SMA and COL-I expression in HSCs. miR-145 promotes HSC activation and liver fibrosis by targeting KLF4.

Knockdown of histidine-rich calcium-binding protein (HRC) suppresses liver fibrosis by inhibiting the activation of hepatic stellate cells

The histidine-rich calcium-binding protein (HRC) is a regulator of Ca²⁺ homeostasis and it plays a significant role in hepatocellular carcinoma (HCC) progression. However, the relationship between HRC and liver fibrogenesis is still unknown. Our data demonstrates that HRC was upregulated in fibrotic liver and activated hepatic stellate cells (HSCs). TGF-β treatment increased α-SMA and HRC expression dose-dependently in HSCs. Repression of HRC reduced α-SMA, CTGF and collagen expression, and inhibited HSC proliferation and migration. In addition, we found that the anti-fibrosis effect of HRC knockdown was associated with endoplasmic reticulum (ER) stress. Silencing of HRC decreased the expression of ER stress and autophagy markers. Moreover, ER stress agonist thapsigargin (TG) enhanced, whereas ER stress antagonist 4-phenylbutyric acid (4-PBA) alleviated HSCs activation and autophagy. In conclusion, these data indicate that depletion of HRC inhibited HSC activation through the ER stress pathway, and HRC may be a potential regulator of liver fibrosis.

Interactions between Autophagy and Inhibitory Cytokines

Autophagy is a degradative pathway that plays an essential role in maintaining cellular homeostasis. Most early studies of autophagy focused on its involvement in age-associated degeneration and nutrient deprivation. However, the immunological functions of autophagy have become more widely studied in recent years. Autophagy has been shown to be an intrinsic cellular defense mechanism in the innate and adaptive immune responses. Cytokines belong to a broad and loose category of proteins and are crucial for innate and adaptive immunity. Inhibitory cytokines have evolved to permit tolerance to self while also contributing to the eradication of invading pathogens. Interactions between inhibitory cytokines and autophagy have recently been reported, revealing a novel mechanism by which autophagy controls the immune response. In this review, we discuss interactions between autophagy and the regulatory cytokines IL-10, transforming growth factor-β, and IL-27. We also mention possible interactions between two newly discovered cytokines, IL-35 and IL-37, and autophagy.

Down-Regulation of Nogo-B Expression as a Newly Identified Feature of Intrahepatic Cholangiocarcinoma

Nogo-B, located in the endoplasmic reticulum, is an isoform belonging to the reticulon protein family, which is expressed specifically in cholangiocytes and non-parenchymal cells in the liver. Nogo-B expression is down-regulated with the progression of liver fibrosis, but its distinct function in liver malignancies has not been fully clarified. We have hypothesized that Nogo-B expression may be altered in intrahepatic cholangiocarcinoma (ICC), a relatively rare type of primary liver cancer with highly malignant behavior. The present study aimed to investigate the relationship between Nogo-B expression, assessed by immunohistochemical staining, and clinicopathological factors and prognosis in 34 ICC patients. Positive expression was observed in 19 (56%) of 34 ICC specimens: 6 patients (18%) with positivity levels of 1+ (positive cells in 10-50% of cancer cells) and 13 patients (38%) with 2+ (positive cells over 50%). Importantly, the remaining 15 patients (44%) were categorized as negative expression (Nogo-B-positive cells, less than 10%). Conversely, the mass-forming type of ICC tended to express Nogo-B with the degree of 2+ positivity, compared to the periductal infiltration type (p = 0.064), and the mass-forming type showed a better 5-year survival rate (66% vs. 5%) after hepatectomy (p < 0.05). However, the degree of positivity was not associated with tumor relapse rate, disease-free and overall survival, although each of the periductal infiltration type, intrahepatic metastasis, larger tumor size, and lower microvessel counts was associated with lower survival rates. We propose that Nogo-B expression is down-regulated in ICC, the implication of which, however, remains to be investigated.

Endoplasmic reticulum (ER) stress protein responses in relation to spatio-temporal dynamics of astroglial responses to status epilepticus in rats

In the present study, we investigated whether endoplasmic reticulum (ER) stress is associated with neuronal- and astroglial-death in the hippocampus using LiCl-pilocarpine-induced status epilepticus (SE) rat model. Glucose-related protein (GRP) 78 and protein disulfide isomerase (PDI) expressions were transiently increased in CA1 neurons and dentate granule cells, and subsequently decreased in these cells following SE. GRP94 and calnexin (CNX) expression was gradually reduced in CA1 neurons, not in dentate granule cells. Phospho-protein kinase RNA (PKR)-like ER kinase (pPERK), phospho-eukaryotic initiation factor 2α (peIF2A) and CCAAT/enhancer-binding protein homologous protein (CHOP) immunoreactivities were observed in 17%, 12% and 7% of degenerating CA1 neurons, respectively. GRP 78 and PDI expressions were also up-regulated in reactive astrocytes within the CA1-3 regions. In the molecular layer of the dentate gyrus, PDI-positive astrocytes showed TUNEL signal, nuclear apoptosis inducing factor translocation and pPERK/peIF2A/CHOP immunoreactivities. Four weeks after SE, clasmatodendritic astrocytes showed pPERK peIF2A and CNX immunoreactivities without CHOP expression. These findings indicate that SE-induced ER stress may be associated with astroglial apoptosis and autophagic astroglial death in the regional-specific pattern.

The Value of Circulating Nogo-B for Evaluating Hepatic Functional Reserve in Patients with Cirrhosis

Objective. To examine Nogo-B in liver tissues and plasma of patients with liver cirrhosis and associate them with various clinical parameters. Materials and Methods. Nogo-B protein expression was examined by immunohistochemistry in 24 human fibrotic/cirrhotic liver specimens and 10 healthy controls. We determined plasma Nogo-B levels by enzyme-linked immunosorbent assay in 301 patients with liver cirrhosis and 153 healthy controls, and then analyzed various clinical parameters. Results. Nogo-B was mainly expressed in nonparenchymal cells in the liver and was marked increased in liver with significant fibrosis/cirrhosis compared to controls. Moreover, Metavir F4 showed a higher level of expression than F2. Plasma Nogo-B levels were significantly higher in cirrhotic patients than in healthy controls and were the highest in Child-Pugh class C patients. Plasma Nogo-B levels were positively correlated with Child-Pugh scores. However, there was no relationship between plasma Nogo-B levels and etiology of liver diseases, ALT, AST, platelet counts, and the severity of esophagogastric varices. Conclusions. Nogo-B is mainly expressed in hepatic nonparenchymal cells and is present in plasma. Abnormally high plasma levels of Nogo-B are associated with hepatic cirrhosis and Child-Pugh score, but not correlated with the grade of liver inflammation or portal hypertension. Plasma Nogo-B may be a novel surrogate marker to reflect liver function reserve.