Decrease in fat de novo synthesis and chemokine ligand expression in non-alcoholic fatty liver disease caused by inhibition of mixed lineage kinase domain-like pseudokinase.

BACKGROUND AND AIM: Receptor-interacting serine/threonine kinase 3 and mixed lineage kinase domain-like pseudokinase (MLKL) have gained attention as apoptosis alternate cell death signaling molecules. We aimed to evaluate the role of MLKL in non-alcoholic fatty liver disease (NAFLD). METHODS: Hepatic tissue MLKL expression was compared between NAFLD patients and healthy controls. High-fat diet was fed to wild-type and MLKL-knockout (KO) mice for 12 weeks. Brown adipose fat tissue was measured by [18 F]-fluorodeoxyglucose positron emission tomography. Energy expenditure was measured by indirect calorimetry. Anti-MLKL effects were also evaluated in in vitro setting using U937 and HepG2 cells. RESULTS: Hepatic tissue MLKL expression increased in NAFLD patients compared with healthy controls. MLKL expression increased according to the degree of steatosis, ballooning, and inflammation. High-fat diet-fed MLKL-KO mice displayed decreased alanine aminotransferase, triglycerides, liver weight, NAFLD activity score (6.3 vs 3.5, P < 0.001), steatosis score (3.0 vs 1.8, P < 0.001), inflammation, and ballooning degeneration compared with wild-type mice. SREBP1c, fatty acid synthase, and SCD-1 expressions decreased in MLKL-KO mice. Adipose tissue F4/80-positive crown-like structures were also reduced in MLKL-KO mice. HepG2 cells treated with necrosulfonamide (an MLKL inhibitor) showed reduced Nile red staining and reduced SREBP1c and SCD-1 expressions. Stimulation of necroptosis using lipopolysaccharide + caspase inhibitor (zVAD) increased CXCL1/2 expressions in U937 monocyte cells. Lipopolysaccharide + zVAD-induced increased expressions of CXCL1/2 were reduced with necrosulfonamide treatment. CONCLUSIONS: Mixed lineage kinase domain-like pseudokinase inhibition has protective effects in non-alcoholic steatohepatitis by decreasing hepatic de novo fat synthesis and chemokine (C-X-C motif) ligand expressions.

Effect of Stem Cell Treatment on Acute Liver Failure Model Using Scaffold.

BACKGROUND: Injecting MSCs via blood vessel is most commonly used method, which has a major drawback of safety. The aim of our study was to evaluate efficacy using scaffold-loaded MSCs in acute liver failure model. METHOD: Acute liver failure was induced in mice using thioacetamide (TAA) (200 mg/kg, i.p) once a day for two consecutive days. The animals were divided in four acute liver failure groups: (1) TAA; (2) empty scaffold; (3) MSCs injected through tail vein; (4) MSC + Scaffold, scaffold loaded with MSCs, to evaluate the mortality and changes in liver function. Polylactic-co-glycolic acid scaffold alone and loaded with human MSCs was implanted on mice dorsum. RESULTS: TAA dose was titrated until one-third mortality rate was achieved. TAA (200 mg/kg) once daily for two consecutive days was injected to establish the acute liver failure model. The mortality of TAA and scaffold groups was 55.9% and 63.2%, respectively. Although, mortality of MSC-TV group decreased 14.7% as compared to TAA group (p = 0.200), MSC + Scaffold group had the lowest mortality (31.4%) (p = 0.013). Cells implanted in PLGA biomaterial were survived until 3 weeks, and their function was increased. Area of hepatic inflammation and necrosis was significantly reduced in MSC-TV and MSC + Scaffold groups; but there was no difference between the two groups. Gene expressions related to inflammation were significantly decreased in MSC-TV and MSC + Scaffold groups compared to TAA group. In MSC + Scaffold group, no migration of stem cells to liver tissue was observed. Although, not all cells in scaffold were stained, some of them were differentiated into hepatocyte-like cells which stained positive for PAS and CYP2E1 antibody. CONCLUSION: Scaffold loaded with MSCs showed protective effects via paracrine signaling on acute liver failure model.

Histologic and Metabolic Derangement in High-Fat, High-Fructose, and Combination Diet Animal Models.

BACKGROUND: We used high-fat (HF), high-fructose (HFr), and combination diets to create a dietary animal model of nonalcoholic fatty liver disease (NAFLD). Comparison of both clinical phenotypes has not been well defined. The purpose of this study was to compare histologic and metabolic characteristics between diets in an animal model of NAFLD. METHODS: NAFLD was induced in rats by feeding them HF, HFr, and combination (HF + HFr) diets for 20 weeks. The degree of intrahepatic fat accumulation, inflammation, and oxidative stress was evaluated. Metabolic derangements were assessed by the oral glucose tolerance test and the intrahepatic insulin signal pathway. RESULTS: Body weight gain and intrahepatic fat accumulation were more prominent in the HF feeding group than in the HFr group. The expressions of NOX-4 and TLR-4 were higher in the HF and HFr combination groups than in the HF-only group. Other intrahepatic inflammatory markers, MCP-1, TNF-α, and endoplasmic reticulum stress markers, were the highest in the HF + HFr combination group. Although intrahepatic fat deposition was less prominent in the HFr diet model, intrahepatic inflammation was noted. CONCLUSIONS: Intrahepatic inflammation and metabolic derangements were more prominent in the HF and HFr combination model than in the HF monodiet model.

SOX trio decrease in the articular cartilage with the advancement of osteoarthritis.

SOX trio (SOX-5, SOX-6, and SOX-9) maintain the chondrocytic phenotypes and are vital for chondrogenesis in embryonic development. The purpose of this study is to investigate the change in the expression of SOX trio with the advancement of osteoarthritis (OA) in human articular cartilage (AC). Human OA samples from eight patients were obtained from the distal femoral condyles during total knee arthroplasty. Minimally OA cartilage taken from areas with no obvious surface defects on lateral condyles was compared with advanced OA cartilage obtained from areas within 1 cm of overt lesion located on medial condyle surface. SOX-5, SOX-6, and SOX-9 gene expressions significantly decreased by 41% (p = 0.047), 46% (p = 0.047), and 56% (p = 0.029) in advanced OA area compared with the minimally OA area. There was a significant decrease in aggrecan and type II collagen (COL2A1) gene expressions by 73% (p = 0.029) and 65% (p = 0.029), respectively, in advanced OA area compared with the minimally OA area. From Western blotting and immunohistochemistry, SOX-5, SOX-6, SOX-9, type II collagen, and aggrecan protein expressions also significantly decreased in advanced OA cartilage compared with minimally OA cartilage. DNA methylation study of SOX-9 promoter regions revealed no difference in the epigenetic status between the two areas. It is concluded that SOX trio gene and protein decreased with advancement of OA in human articular cartilage.

The Use of Foxa2-Overexpressing Adipose Tissue-Derived Stem Cells in a Scaffold System Attenuates Acute Liver Injury.

Background/Aims: For the clinical application of stem cell therapy, functional enhancement is needed to increase the survival rate and the engraftment rate. The purpose of this study was to investigate functional enhancement of the paracrine effect using stem cells and hepatocyte-like cells and to minimize stem cell homing by using a scaffold system in a liver disease model. Methods: A microporator was used to overexpress Foxa2 in adipose tissue-derived stem cells (ADSCs), which were cultured in a poly(lactic-co-glycolic acid) (PLGA) scaffold. Later, the ADSCs were cultured in hepatic differentiation medium for 2 weeks by a 3-step method. For in vivo experiments, Foxa2-overexpressing ADSCs were loaded in the scaffold, cultured in hepatic differentiation medium and later were implanted in the dorsa of nude mice subjected to acute liver injury (thioacetamide intraperitoneal injection). Results: Foxa2-overexpressing ADSCs showed greater increases in hepatocyte-specific gene markers (alpha fetoprotein [AFP], cytokeratin 18 [CK18], and albumin), cytoplasmic glycogen storage, and cytochrome P450 expression than cells that underwent the conventional differentiation method. In vivo experiments using the nude mouse model showed that 2 weeks after scaffold implantation, the mRNA expression of AFP, CK18, dipeptidyl peptidase 4 (CD26), and connexin 32 (CX32) was higher in the Foxa2-overexpressing ADSCs group than in the ADSCs group. The Foxa2-overexpressing ADSCs scaffold treatment group showed attenuated liver injury without stem cell homing in the thioacetamide-induced acute liver injury model. Conclusions: Foxa2-overexpressing ADSCs applied in a scaffold system enhanced hepatocyte-like differentiation and attenuated acute liver damage in an acute liver injury model without homing effects.

Mismatched effects of receptor interacting protein kinase-3 on hepatic steatosis and inflammation in non-alcoholic fatty liver disease.

AIM: To validate the effects of receptor interacting protein kinase-3 (RIP3) deletion in non-alcoholic fatty liver disease (NAFLD) and to clarify the mechanism of action. METHODS: Wild-type (WT) and RIP3 knockout (KO) mice were fed normal chow and high fat (HF) diets for 12 wk. The body weight was assessed once weekly. After 12 wk, the liver and serum samples were extracted. The liver tissue expression levels of RIP3, microsomal triglyceride transfer protein, protein disulfide isomerase, apolipoprotein-B, X-box binding protein-1, sterol regulatory element-binding protein-1c, fatty acid synthase, cluster of differentiation-36, diglyceride acyltransferase, peroxisome proliferator-activated receptor alpha, tumor necrosis factor-alpha (TNF-α), and interleukin-6 were assessed. Oleic acid treated primary hepatocytes from WT and RIP3KO mice were stained with Nile red. The expression of inflammatory cytokines, including chemokine (C-X-C motif) ligand (CXCL) 1, CXCL2, and TNF-α, in monocytes was evaluated. RESULTS: RIP3KO HF diet fed mice showed a significant gain in body weight, and liver weight, liver to body weight ratio, and liver triglycerides were increased in HF diet fed RIP3KO mice compared to HF diet fed WT mice. RIP3KO primary hepatocytes also had increased intracellular fat droplets compared to WT primary hepatocytes after oleic acid treatment. RIP3 overexpression decreased hepatic fat content. Quantitative real-time polymerase chain reaction analysis showed that the expression of very-low-density lipoproteins secretion markers (microsomal triglyceride transfer protein, protein disulfide isomerase, and apolipoprotein-B) was significantly suppressed in RIP3KO mice. The overall NAFLD Activity Score was the same between WT and RIP3KO mice; however, RIP3KO mice had increased fatty change and decreased lobular inflammation compared to WT mice. Inflammatory signals (CXCL1/2, TNF-α, and interleukin-6) increased after lipopolysaccharide and pan-caspase inhibitor (necroptotic condition) treatment in monocytes. Neutrophil chemokines (CXCL1, and CXCL2) were decreased, and TNF-α was increased after RIP3 inhibitor treatment in monocytes. CONCLUSION: RIP3 deletion exacerbates steatosis, and partially inhibits inflammation in the HF diet induced NAFLD model.

Does necroptosis have a crucial role in hepatic ischemia-reperfusion injury?

BACKGROUND: Previous studies have demonstrated protective effects of anti-receptor interacting protein kinase 1 (RIP1), a key necroptosis molecule. However, it is uncertain whether necroptosis has a crucial role in hepatic IR injury. Therefore, we evaluated the role of necroptosis in hepatic IR injury. METHOD: The IR mice underwent 70% segmental IR injury induced by the clamping of the hepatic artery and portal vein for 1 hr followed by reperfusion for 4 hr. The key necroptosis molecules (RIP1, RIP3, and MLKL) and other key molecules of regulated necrosis (PGAM5 and caspase-1) were evaluated in the warm IR injury model. A RIP1 inhibitor (necrostain-1s) and/or an anti-mitochondrial permeability transition (MPT)-mediated necrosis mediator (cyclosporine A, CyA) were administered before clamping. Necrotic injury was quantified using Suzuki's scoring system. qRT-PCR and western blot were performed to evaluate RIP1, RIP3, MLKL and PGAM5 expressions. RESULTS: RIP1, RIP3, MLKL and PGAM5 expression did not change in the hepatic IR injury model. Moreover, Nec1s pretreatment did not improve histology or biochemical markers. The overall Suzuki score (cytoplasmic vacuolization, sinusoidal congestion and hepatocytes necrosis) was increased in the RIP3(-/-) mice compared to the IR group (3.5 vs. 5, p = 0.026). CyA pretreatment and/or RIP3(-/-) mice decreased Bax/Bcl2 expression; however, it did lead to an overall change in the levels of AST, ALT and LDH or necrotic injury. The Bax/Bcl2 ratio and the expression of caspase-1 and caspase-3 did not increase in our hepatic IR injury model. CONCLUSION: Key necroptosis molecules did not increase in the necrosis-dominant hepatic IR injury model. Anti-necroptosis and/or cyclosporine-A treatment did not have an overall protective effect on necrosis-dominant hepatic IR injury.

Granulocyte colony stimulating factor treatment in non-alcoholic fatty liver disease: beyond marrow cell mobilization.

Protective effects of granulocyte colony stimulating factor (G-CSF) in acute liver injury via marrow cell mobilization have been reported in several studies. But exact mode of action and optimal protocol of G-CSF has been still doubt in chronic disease. Here we investigated mode of action and optimization of G-CSF as a treatment for non-alcoholic fatty liver disease (NAFLD). Various doses of conventional G-CSF (30 µg/kg once weekly, once daily for 5 days, twice weekly) and long acting G-CSF (30 µg/kg once a month) were evaluated in two kinds of NAFLD animal models to optimize the G-CSF protocol. G-CSF receptor expression highest increased in NAFLD model among various liver diseases compare to control (NAFLD: 14.7 times, alcohol hepatitis: 7.1 times, cirrhosis: 2.4 times, and ischemia reperfusion: 6.8 times). G-CSF treatment reduced intrahepatic fat accumulation, and inflammation in two kinds of NAFLD animal models. G-CSF increased PI3K/Akt expression in hepatocyte as well as decreased apoptotic drive (increased Bcl-2 expression and decreased Bax expression) in animal model. Five day consecutive G-CSF treatment and once a month long acting G-CSF increased marrow derived stem cell marker in peripheral blood. But twice a week conventional G-CSF treatment did not increased CD34+ cell in peripheral blood and liver neither. Not only high dose G-CSF (once daily for 5 days) but also hepatotropic dose G-CSF (twice a week) significantly reduced hepatocyte apoptosis via PI3K and Akt pathway activation without marrow cell mobilization in NAFLD animal model.

Osthol attenuates hepatic steatosis via decreased triglyceride synthesis not by insulin resistance.

AIM: To evaluate the effects of osthol on intrahepatic fat synthesis, ß-oxidation, inflammation, and insulin resistance by multifaceted analysis. METHODS: Sprague-Dawley rats (n = 30) were randomly divided into control, non-alcoholic fatty liver disease (NAFLD), and osthol groups. NAFLD and osthol groups were fed with a high-fat diet for 14 wk. After 8 wk of the high-fat diet, the osthol group also received osthol 20 mg/kg orally 5 times/wk. To assess the insulin resistance, oral glucose tolerance was performed at the end of 14 wk. Immunohistochemical (4-HNE, F4/80) and hematoxylin and eosin (HE) staining were performed on liver tissue extracts after animal sacrifice at 14 wk. SREBP1c, FAS, SCD-1, PPAR-α, CROT, MCP-1, IRS-1, and IRS-2 mRNA expressions were assessed with reverse transcription-polymerase chain reaction. RESULTS: HE staining revealed that, compared with the NAFLD group, the osthol group showed significantly decreased intrahepatic fat content (39.4% vs 21.0%; P = 0.021). SREBP1c expression in the NAFLD group increased compared to controls (P = 0.0001), while osthol treatment decreased SREBP1c expression compared with the NAFLD group (P = 0.0059). In the osthol group, intrahepatic FAS and SCD-1, which act downstream of SREBP1c, decreased significantly compared with the NAFLD group. Moreover, PPAR-α expression in the osthol group was also significantly higher than in the NAFLD group (P = 0.0147). CONCLUSION: Osthol treatment attenuated liver steatosis by decreasing de novo liver triglyceride synthesis and had nominal effects on insulin resistance and liver inflammation.

Electroporation-mediated transfer of Runx2 and Osterix genes to enhance osteogenesis of adipose stem cells.

In the present study, we tested the hypothesis that electroporation-mediated transfer of Runx2, Osterix, or both genes enhances the in vitro and in vivo osteogenesis from adipose stem cells (ASCs). ASCs were transfected with Runx2, Osterix, or both genes using electroporation, and further cultured in monolayer or in PLGA scaffold under osteogenic medium for 14 days, then analyzed for in vitro osteogenic differentiation. Transfected ASC-PLGA scaffold hybrids were also implanted on nude mice to test for in vivo ectopic bone formation. Runx2 and Osterix genes were strongly expressed in ASCs transfected with each gene on day 7, decreasing rapidly on day 14. Runx2 protein was strongly expressed in ASCs transfected with the Runx2 gene, while Osterix protein was strongly expressed in ASCs transfected with either or both Runx2 and Osterix genes. Overexpression of Runx2 and Osterix significantly increased the gene expression of osteogenic differentiation markers (alkaline phosphatase [ALP], osteocalcin [OCN], type I collagen [COL1A1], and bone sialoprotein [BSP]) in ASCs. Transfection of Runx2 and Osterix genes enhanced the protein expression of OCN, type I collagen, and BSP, as demonstrated by Western blot analysis, and ALP activity as well as enhancing mineralization in the monolayer culture and ASC-PLGA scaffold hybrids. Runx2- or Osterix-transfected ASC-PLGA scaffold hybrids promoted bone formation in nude mice after 6 weeks of in vivo implantation.

Influence of chondrocytes on the chondrogenic differentiation of adipose stem cells.

In this study, whether or not chondrogenic differentiation of adipose-derived stem cells (ASCs) could be enhanced by soluble factors from or coculture with chondrocytes was determined. In vitro pellet cultures were carried out in five ways using ASCs or chondrocytes in passage 3 as follows: #1, 2.5 × 105 ASCs were cultured in Dulbecco's modified Eagle's medium/F-12 supplemented with 1% ITS, 10⁻7 M dexamethasone, 50 µM ascorbate-2-phosphate, 50 µM L-proline, and 1 mM sodium pyruvate; #2, 2.5 × 105 chondrocytes were cultured in the same medium as #1: #3, 1.25 × 105 ASCs and 1.25 × 105 chondrocytes were mixed and cocultured in the same medium as #1; #4, 2.5 × 105 ASCs were cultured in a medium that was a 1:1 mixture of the same fresh medium as #1 and conditioned medium from chondrocyte culture (#2); #5, 2.5 × 105 ASCs were cultured in the same medium as #1 and 5 ng/mL of transforming growth factor-ß2 and 100 ng/mL of BMP-7. After 3 weeks, the glycosaminoglycan level that normalized to the DNA amount was significantly increased by 25% in ASCs treated with condition medium from chondrocyte cultures (p = 0.028) and by 37% in ASC-chondrocyte cocultures (p = 0.042). The glycosaminoglycan level was 37% greater in chondrocytes (p = 0.046) and 50% greater in ASCs cultured under growth factor cocktails than the control ASCs. The gene expression of SOX-9 significantly increased by >10-fold (p < 0.05) in ASCs treated with the conditioned medium from chondrocyte cultures and ASC-chondrocyte cocultures compared with the control ASCs; whereas COL2A1 significantly increased ~100-fold (p < 0.05) in either condition. COL10A1 gene expression increased by treating either with conditioned medium or with coculture (p < 0.05), but COL1A1 gene expression did not significantly change in either condition. Western blotting of SOX-9 and immunochemistry for types II, I, and X collagen largely parallel the results from gene expression studies. It is concluded that the signals from chondrocytes, in the form of soluble factors or by direct interaction, effectively promote chondrogenic differentiation of ASCs during in vitro pellet culture. This work may present a simple and innovative method for generating cartilaginous tissue from ASCs and shed a new light in cartilage tissue engineering from ASCs.