Novel Interplay Between Sonic Hedgehog and Transforming Growth Factor-β1 in Human Nonalcoholic Steatohepatitis

Pirfenidone ameliorates liver steatosis by targeting the STAT3-SCD1 axis

OBJECTIVE

Previous studies reported that pirfenidone (PFD) is associated with liver disease. However, the effects of pirfenidone on energy metabolism and hepatic lipid accumulation are still poorly understood.

METHODS

In this study, C57BL/6J mice were randomly divided into two groups, and fed a normal chow diet (NCD) or a high-fat diet (HFD) for 16 weeks. At the end of the eighth week, half of the mice fed on both diets were treated with PFD. Biochemical and lipid metabolism-related indices were analyzed. Furthermore, Hepa 1-6 cells and mouse primary hepatocytes (MPHs) were incubated with PFD with or without free fatty acid (FFA) treatment. Then, stattic (a p-STAT3 inhibitor) or Ad-shSTAT3 was used to further elucidate the effects of Signal Transducer and Activator of Transcription 3 (STAT3) signaling on PFD regulation of hepatic steatosis.

RESULTS

PFD ameliorated obesity and hepatic lipid deposition in HFD mice by decreasing stearoyl-CoA desaturase 1 (SCD1) expression and upregulating p-STAT3 in the liver. In Hepa 1-6 cells and MPHs, PFD also down-regulated the expression of SCD1. STAT3 inhibition treatment eliminated the benefits of PFD on both SCD1 and hepatic steatosis.

CONCLUSION

In summary, our data reveal that PFD may play an important role in mitigating hepatic steatosis in a STAT3-SCD1-dependent manner.

[Transforming growth factor-β1 induces transformation of rat meningeal fibroblasts into myofibroblasts by upregulating Shh signaling]

OBJECTIVE

To investigate the effect of TGF-β1 on Shh signaling pathway during the transformation of meningeal fibroblasts into myofibroblasts.

METHODS

Primary meningeal fibroblasts were isolated from neonatal (24 h) SD rats and purified using type Ⅳ collagenase. The isolated cells were treated with 10 ng/mL TGF-β1 alone or in combination with 20 μmol/L SB-431542 (a TGF-β1 receptor inhibitor) for 72 h, and the changes in proliferation and migration abilities of the fibroblasts were assessed with CCK-8 assay and cell scratch test. The expression of fibronectin (Fn) was detected with immunofluorescence assay, and Western blotting was performed to examine the expressions of Fn, α-SMA and Shh protein in the cells; the expression of Shh mRNA was detected with real-time fluorescence quantitative PCR.

RESULTS

TGF-β1 treatment obviously enhanced the proliferation and migration of primary meningeal fibroblasts (P < 0.05), and promoted the transformation of meningeal fibroblasts into myofibroblasts and the secretion of Fn (P < 0.05). TGF-β1 treatment also upregulated the expression of Shh at both protein and mRNA levels (P < 0.05). Treatment with SB-431542 partially blocked the effect of TGF-β1 on the transformation of meningeal fibroblasts (P < 0.05).

CONCLUSION

TGF-β1 can induce the transformation of meningeal fibroblasts into myofibroblasts by up-regulating Shh expression in Sonic Hedgehog signaling pathway.

Hepatic stellate cell activation by TGFβ induces hedgehog signaling and endoplasmic reticulum stress simultaneously

Activation of hepatic stellates (HSCs) is known as the major cause of initiation and progression of liver fibrosis. A wide array of events occurs during HSC activation including induction of hedgehog (Hh) signaling and endoplasmic reticulum (ER) stress. Targeting HSC activation may provide promising insights into liver fibrosis treatment. In this regard, establishing in vitro models which can mimic the molecular pathways of interest is very important. We aimed to activate HSC in which Hh signaling and ER stress are stimulated simultaneously. We used 5 ng/ml TGFβ to activate LX-2 cells, HSC cell line. Gene expression analysis using qRT-PCR, immunostaining and immunoblotting were performed to show HSC activation associated markers. Furthermore, the migration capacity of the TGFβ treated cells is evaluated. The results demonstrated that major fibrogenic markers including collagen1a, lysyl oxidase, and tissue inhibitor of matrix metalloproteinase 1 genes are up-regulated significantly. In addition, our immunofluorescence and immunoblotting results showed that protein levels of GLI-2 and XBP1, were enhanced. Moreover, we found that TGFβ treatment reduced the migration of LX-2 cells. Our results are compatible with high throughput data analysis with respect to differentially expressed genes of activated HSC compared to the quiescent ones. Moreover, our findings suggest that quercetin can reduce fibrogenic markers of activated HSCs as well as osteopontin expression, a target gene of hedgehog signaling.

Hedgehog Pathway Inhibitors against Tumor Microenvironment

Targeting the hedgehog (HH) pathway to treat aggressive cancers of the brain, breast, pancreas, and prostate has been ongoing for decades. Gli gene amplifications have been long discovered within malignant glioma patients, and since then, inhibitors against HH pathway-associated molecules have successfully reached the clinical stage where several of them have been approved by the FDA. Albeit this success rate implies suitable progress, clinically used HH pathway inhibitors fail to treat patients with metastatic or recurrent disease. This is mainly due to heterogeneous tumor cells that have acquired resistance to the inhibitors along with the obstacle of effectively targeting the tumor microenvironment (TME). Severe side effects such as hyponatremia, diarrhea, fatigue, amenorrhea, nausea, hair loss, abnormal taste, and weight loss have also been reported. Furthermore, HH signaling is known to be involved in the regulation of immune cell maturation, angiogenesis, inflammation, and polarization of macrophages and myeloid-derived suppressor cells. It is critical to determine key mechanisms that can be targeted at different levels of tumor development and progression to address various clinical issues. Hence current research focus encompasses understanding how HH controls TME to develop TME altering and combinatorial targeting strategies. In this review, we aim to discuss the pros and cons of targeting HH signaling molecules, understand the mechanism involved in treatment resistance, reveal the role of the HH pathway in anti-tumor immune response, and explore the development of potential combination treatment of immune checkpoint inhibitors with HH pathway inhibitors to target HH-driven cancers.

Increased atherogenic lipoprotein profile in children with non-alcoholic steatohepatitis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has been shown to be an independent risk factor for cardiovascular disease. In adults, histologic severity of non-alcoholic steatohepatitis (NASH) is associated with a more atherogenic profile.

OBJECTIVE

To assess cardiovascular disease risk by lipoprotein profile in children with NAFLD and compare to histologic assessment of severity.

METHODS

Nuclear magnetic resonance lipoprotein profile including lipoprotein particle sizes, apolipoproteins and the lipoprotein insulin resistance (LP-IR) index was measured in serum samples collected from 76 children at the time of a clinically indicated liver biopsy for NAFLD. Liver histology was scored using the NASH Clinical Research Network criteria and grouped into NASH or non-NASH.

RESULTS

Children with NASH had higher apolipoprotein B to apolipoprotein AI, ApoB/ApoAI (0.56 [IQR, 0.45-0.70] vs 0.66 [IQR, 0.56-0.79], P = .02) and higher LP-IR index (61 ± 21.9 vs 68 ± 17.3, P = .05) compared to children with non-NASH. Severity of hepatocyte ballooning was associated with higher ApoB/ApoAI ratios (P = .01), while high-density lipoprotein size was inversely associated with hepatic fat accumulation (P = .04).

CONCLUSION

While dyslipidaemia is common among children with NAFLD, this data suggests severity of the histologic features is closely associated with severity of cardiometabolic risk. Further studies are needed to understand the role of treatment of NASH in children to prevent future cardiometabolic disease.

"Hedgehog pathway": a potential target of itraconazole in the treatment of cancer

PURPOSE

Itraconazole is an antifungal drug that has been clinically used for over 30 years. In recent years, scholars have discovered that it possesses an anticancer effect. Moreover, its mechanism has been clarified to some degree. What deserves to be mentioned is that itraconazole acting on the Hedgehog pathway has made a new progress in the treatment of cancers. While interestingly, studies have demonstrated that the Hedgehog pathway is largely activated in different cancer cells.

RESULT

This review tries to highlight the effect of itraconazole on smoothened receptor (SMO) in the Hedgehog pathway, thereby reducing the glioma-associated oncogene homolog (GLI) release and finally exhibiting a range of anticancer effects, promoting apoptosis of cancer cells, and inhibiting proliferation by indirect inhibition of NF-κB pathway and inflammation, moreover, promoting the expression of cyclin-dependent kinase inhibitors, inhibiting the expression of target genes transcribed by GLI such as BCL-2 and Cyclin-D1. Besides, itraconazole increases the number of Bnip3, subsequently, inducing the dissociation of the Beclin-1/BCL-2 binding complex, as a result of ultimately promoting autophagy of cancer cells.

CONCLUSION

As a new anticancer drug, whether itraconazole eventually entering clinical application requires the joint eforts of all scholars. In any case, an in-depth study on itraconazole will bring new hope for cancer patients in the near future.

FGF21: An Emerging Therapeutic Target for Non-Alcoholic Steatohepatitis and Related Metabolic Diseases

The rising global prevalence of obesity, metabolic syndrome, and type 2 diabetes has driven a sharp increase in non-alcoholic fatty liver disease (NAFLD), characterized by excessive fat accumulation in the liver. Approximately one-sixth of the NAFLD population progresses to non-alcoholic steatohepatitis (NASH) with liver inflammation, hepatocyte injury and cell death, liver fibrosis and cirrhosis. NASH is one of the leading causes of liver transplant, and an increasingly common cause of hepatocellular carcinoma (HCC), underscoring the need for intervention. The complex pathophysiology of NASH, and a predicted prevalence of 3-5% of the adult population worldwide, has prompted drug development programs aimed at multiple targets across all stages of the disease. Currently, there are no approved therapeutics. Liver-related morbidity and mortality are highest in more advanced fibrotic NASH, which has led to an early focus on anti-fibrotic approaches to prevent progression to cirrhosis and HCC. Due to limited clinical efficacy, anti-fibrotic approaches have been superseded by mechanisms that target the underlying driver of NASH pathogenesis, namely steatosis, which drives hepatocyte injury and downstream inflammation and fibrosis. Among this wave of therapeutic mechanisms targeting the underlying pathogenesis of NASH, the hormone fibroblast growth factor 21 (FGF21) holds considerable promise; it decreases liver fat and hepatocyte injury while suppressing inflammation and fibrosis across multiple preclinical studies. In this review, we summarize preclinical and clinical data from studies with FGF21 and FGF21 analogs, in the context of the pathophysiology of NASH and underlying metabolic diseases.

Recent Insight into the Role of Fibrosis in Nonalcoholic Steatohepatitis-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most widespread tumors in the world and its prognosis is poor because of lack of effective treatments. Epidemiological studies show that non-alcoholic steatohepatitis (NASH) and advanced fibrosis represent a relevant risk factors to the HCC development. However little is known of pathophysiological mechanisms linking liver fibrogenesis to HCC in NASH. Recent advances in scientific research allowed to discover some mechanisms that may represent potential therapeutic targets. These include the integrin signaling, hepatic stellate cells (HSCs) activation, Hedgehog signaling and alteration of immune system. In the near future, knowledge of fibrosis-dependent carcinogenic mechanisms, will help optimize antifibrotic therapies as an approach to prevent and treat HCC in patients with NASH and advanced fibrosis.