Mesenchymal stem cells restore CCl4‐induced liver injury by an antioxidative process

We have investigated BM (bone marrow)‐derived MSCs (mesenchymal stem cells) for the treatment of liver injury. It was hypothesized that MSC‐mediated resolution of liver injury could occur through an antioxidative process. After being injected with CCl₄ (carbon tetrachloride), mice were injected with syngenic BM‐derived MSCs or normal saline. Oxidative stress activity of the MSCs was determined by the analysis of ROS (reactive oxygen species) and SOD (superoxide dismutase) activity. In addition, cytoprotective genes of the liver tissue were assessed by real‐time PCR and ARE (antioxidant‐response element) reporter assay. Up‐regulated ROS of CCl₄‐treated liver cells was attenuated by co‐culturing with MSCs. Suppression of SOD by adding an SOD inhibitor decreased the effect of MSCs on injured liver cells. MSCs significantly increased SOD activity and inhibited ROS production in the injured liver. The gene expression levels of Hmox‐1 (haem oxygenase‐1), BI‐1 (Bax inhibitor‐1), HGF (hepatocyte growth factor), GST (glutathione transferase) and Nrf2 (nuclear factor‐erythoid 2 p45 subunit‐related factor 20), attenuated by CCl₄, were increased up to basal levels after MSC transplantation. In addition, MSCs induced an ARE, shown by luciferase activity, which represented a cytoprotective response in the injured liver. Evidence of a new cytoprotective effect is shown in which MSCs promote an antioxidant response and supports the potential of using MSC transplantation as an effective treatment modality for liver disease.     

Prophylactic and Therapeutic Potential of Acetyl‐l‐carnitine against Acetaminophen‐Induced Hepatotoxicity in Mice

Prophylactic and therapeutic effects of acetylcarnitine against acetaminophen‐induced hepatotoxicity were studied in mice. To evaluate the prophylactic effects of acetylcarnitine, mice were supplemented with acetylcarnitine (2 mmol/kg/day per oral (p.o.) for 5 days) before a single dose of acetaminophen (350 mg/kg intraperitoneal (i.p.)). Animals were sacrificed 6 h after acetaminophen injection. Acetaminophen significantly increased the markers of liver injury, hepatic reactive oxygen species, and nitrate/nitrite, and decreased hepatic glutathione (GSH) and the antioxidant enzymes. Acetylcarnitine supplementation resulted in reversal of all biochemical parameters toward the control values. To explore the therapeutic effects of acetylcarnitine, mice were given a single dose of acetylcarnitine (0.5, 1, and 2 mmol/kg p.o.) 1.5 h after acetaminophen. Animals were sacrificed 6 h after acetaminophen. Acetylcarnitine administration resulted in partial reversal of liver injury only at 2 mmol/kg p.o. At equimolar doses, N‐acetylcystiene was superior as therapeutic agent to acetylcarnitine. However, acetylcarnitine potentiated the effect of N‐acetylcystiene in the treatment of acetaminophen toxicity.     

The Protective Roles of IL‐6 Trans‐Signaling Regulated by ADAM9 on the Liver in Carbon Tetrachloride‐Induced Liver Injury in Mice

Our study was undertaken to evaluate the important role that a disintegrin and metalloproteinase 9 (ADAM9) regulates IL‐6 trans‐signaling in carbon tetrachloride (CCl₄)‐induced liver injury in mice. Mice were divided into four groups. Each group respectively received mineral oil injection, CCl₄ injection, anti‐ADAM9 monoclonal antibody (mAb) pretreatment and CCl₄ injection, anti‐ADAM9 mAb and recombinant mouse ADAM9 molecules pretreatment with CCl₄ injection. Our results showed that anti‐ADAM9 mAb pretreatment significantly aggravated liver injury, inhibited IL‐6 trans‐signaling, which led to downregulation of proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), upregulation of Caspase3, cytochrome P450 2E1 (CYP2E1), and hepatocytes apoptosis at 24 h after CCl₄ injection. Recombinant ADAM9 molecules pretreatment reversed the impact of anti‐ADAM9 mAb pretreatment in mice. In conclusion, our study suggested that ADAM9 could regulate the hepatocytes proliferation, apoptosis, angiogenesis, and CYP2E1 expression by activating IL‐6 trans‐signaling and play important protective roles during CCl₄‐induced liver injury in mice.     

Pathologic role of stressed-induced glucocorticoids in drug-induced liver injury in mice

We previously reported that acetaminophen (APAP)-induced liver injury (AILI) in mice is associated with a rise in serum levels of the glucocorticoid (GC), corticosterone. In the current study, we provide evidence that endogenous GC play a pathologic role in AILI. Specifically, pretreatment of mice with the GC receptor (GCR) inhibitor, RU486 (mifepristrone), protected normal but not adrenalectomized mice from AILI, while pretreatment with dexamethasone, a synthetic GC, exacerbated AILI. RU486 did not affect the depletion of whole liver reduced GSH or the formation of APAP-protein adducts. It also had no effects on the formation of reactive oxygen species or the depletion of mitochondrial GSH or ATP. While RU486 pretreatment also protected against halothane-induced liver injury, it exacerbated concanavalin A (ConA)- and carbon tetrachloride (CCl₄)-induced liver injury, demonstrating the complexity of GC effects in different types of liver injury. Conclusion: These results suggest that under certain conditions, elevated levels of GC might represent a previously unappreciated risk factor for liver injury caused by APAP and other drugs through the diverse biological processes regulated by GCR.     

β‐Hydroxybutyrate exacerbates lipopolysaccharide/ d‐galactosamine‐induced inflammatory response and hepatocyte apoptosis in mice

β‐Hydroxybutyrate (BHB), one of ketone body, has been traditionally regarded as an alternative carrier of energy, but recent studies found that BHB plays versatile roles in inflammation. It has been previously reported that the level BHB declined in mice with lipopolysaccharide (LPS)/d ‐galactosamine (d ‐Gal)‐induced liver damage, but the pathological significance remains unclear. In the present study, the pathophysiological roles of BHB in LPS/d ‐Gal‐induced hepatic damage has been investigated. The results indicated pretreatment with BHB further enhanced LPS/d ‐Gal‐induced elevation of aspartate aminotransferase and alanine aminotransferase, exacerbated the histological abnormalities and increased the mortality. Pretreatment with BHB upregulated the level of tumor necrosis factor α and interleukin‐6 in plasma, promoted the activities of caspase‐3, caspase‐8, and caspase‐9 and increased the count of terminal deoxynucleotidyl transferase dUTP nick end labeling‐positive cells. In addition, post‐insult supplement with BHB also potentiated LPS/d ‐Gal‐induced apoptotic liver damage. Therefore, BHB might be a detrimental factor in LPS/d ‐Gal‐induced liver injury via enhancing the inflammation and the apoptosis in the liver.     

Carbonyl Traps as Potential Protective Agents against Methimazole‑Induced Liver Injury

Liver injury is a deleterious adverse effect associated with methimazole administration, and reactive intermediates are suspected to be involved in this complication. Glyoxal is an expected reactive intermediate produced during methimazole metabolism. Current investigation was undertaken to evaluate the role of carnosine, metformin, and N‐acetyl cysteine as putative glyoxal (carbonyl) traps, against methimazole‐induced hepatotoxicity. Methimazole (100 mg/kg, intraperitoneally) was administered to intact and/or glutathione (GSH)?depleted mice and the role of glyoxal trapping agents was investigated. Methimazole caused liver injury as revealed by an increase in serum alanine aminotransferase and aspartate aminotransferase. Moreover, lipid peroxidation and protein carbonylation occurred significantly in methimazole?treated animals’ liver. Hepatic GSH reservoirs were decreased, and inflammatory cells infiltration was observed in liver histopathology. Methimazole?induced hepatotoxicity was severe in GSH‐depleted mice and accompanied with interstitial hemorrhage and necrosis of the liver. Glyoxal trapping agents effectively diminished methimazole‐induced liver injury both in intact and/or GSH?depleted animals.     

Effects of Melatonin‐Aided Therapy on the Glutathione Antioxidant System Activity and Liver Protection

Acute hepatitis results from oxidative stress triggered by hepatotoxic drugs causing liver injury and the activation of caspases cascade. The glutathione antioxidant system protects against reactive oxygen species and mitigates development of these processes. The effectiveness of silymarin, a polyphenolic flavonoid, essenthiale, composed of phosphatidyl choline, and melaxen, a melatonin‐correcting drug, as hepatoprotectors has been investigated. The variation of 6‐sulfatoxymelatonin (aMT6s), resulting from the biotransformation of melatonin, and GSH has been measured. The activities of caspase‐1 and caspase‐3, glutathione antioxidant system, and NADPH‐generating enzymes were determined. The aMT6s decreases in patients with drug hepatitis and recovers with administration of mexalen. GSH increased in the presence of the studied hepatoprotectors. Pathologically activated caspase‐1 and caspase‐3 decreased their activities in the presence of hepatoprotectors with melaxen showing the highest effect. The positive effect of melatonin appears to be related to the suppression of decompensation of the glutathione antioxidant system functions, recovery of liver redox status, and the attenuation of inhibition of the NADPH supply.     

Sirt1–hypoxia‐inducible factor‐1α interaction is a key mediator of tubulointerstitial damage in the aged kidney

Although it is known that the expression and activity of sirtuin 1 (Sirt1) decrease in the aged kidney, the role of interaction between Sirt1 and hypoxia‐inducible factor (HIF)‐1α is largely unknown. In this study, we investigated whether HIF‐1α could be a deacetylation target of Sirt1 and the effect of their interaction on age‐associated renal injury. Five‐week‐old (young) and 24‐month‐old (old) C57Bl/6J mice were assessed for their age‐associated changes. Kidneys from aged mice showed increased infiltration of CD68‐positive macrophages, higher expression of extracellular matrix (ECM) proteins, and more apoptosis than young controls. They also showed decreased Sirt1 expression along with increased acetylated HIF‐1α. The level of Bcl‐2/adenovirus E1B‐interacting protein 3, carbonic anhydrase 9, Snail, and transforming growth factor‐β1, which are regulated by HIF‐1α, was significantly higher in aged mice suggesting that HIF‐1α activity was increased. In HK‐2 cells, Sirt1 inhibitor sirtinol and siRNA‐mediated knockdown of Sirt1 enhanced apoptosis and ECM accumulation. During hypoxia, Sirt1 was down‐regulated, which allowed the acetylation and activation of HIF‐1α. Resveratrol, a Sirt1 activator, effectively prevented hypoxia‐induced production of ECM proteins, mitochondrial damage, reactive oxygen species generation, and apoptosis. The inhibition of HIF‐1α activity by Sirt1‐induced deacetylation of HIF‐1α was confirmed by Sirt1 overexpression under hypoxic conditions and by resveratrol treatment or Sirt1 overexpression in HIF‐1α‐transfected HK‐2 cells. Finally, we confirmed that chronic activation of HIF‐1α promoted apoptosis and fibrosis, using tubular cell‐specific HIF‐1α transgenic mice. Taken together, our data suggest that Sirt1‐induced deacetylation of HIF‐1α may have protective effects against tubulointerstitial damage in aged kidney.     

Expression of Glucose‐6‐Phosphate Dehydrogenase and 6‐Phosphogluconate Dehydrogenase in Oxidative Stress Induced by Long‐Term Iron Toxicity in Rat Liver

Reactive oxygen species (ROS) are highly reactive and oxygen‐containing molecules that are derived by metabolic activities or from environmental sources. Toxicity of heavy metals including iron has the ability to generate ROS in all living organisms. The pentose phosphate pathway enzymes, which are glucose 6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase, produce nicotinamide adenine dinucleotide phosphate (NADPH) that enables cells to counterbalance the oxidative stress via the action of the glutathione system. The results presented here have shown that toxic and nontoxic levels of iron have a strong effect on the expression of both genes. While toxic levels of iron exhibited significant changes in enzyme activity, nontoxic levels had no effect on enzymes in rat liver. Our results are the first evidence to elucidate how oxidative stress induced by long‐term iron toxicity affects both enzymes at the enzymatic and molecular level and also to determine any possible correlation between the enzymatic and molecular levels.     

Inhibition of MD2‐dependent inflammation attenuates the progression of non‐alcoholic fatty liver disease

Non‐alcoholic fatty liver disease (NAFLD) can progress to the more serious non‐alcoholic steatohepatitis (NASH), characterized by inflammatory injury and fibrosis. The pathogenic basis of NAFLD progressing to NASH is currently unknown, but growing evidence suggests MD2 (myeloid differentiation factor 2), an accessory protein of TLR4, is an important signalling component contributing to this disease. We evaluated the effectiveness of the specific MD2 inhibitor, L6H21, in reducing inflammatory liver injury in a relevant high‐fat diet (HFD) mouse model of NASH and in the palmitic acid (PA)‐stimulated human liver cell line (HepG2). For study, genetic knockout (MD2^?/?) mice were fed a HFD or control diet for 24 weeks, or wild‐type mice placed on a similar diet regimen and treated with L6H21 for the last 8 or 16 weeks. Results indicated that MD2 inhibition with L6H21 was as effective as MD2 knockout in preventing the HFD‐induced hepatic lipid accumulation, pro‐fibrotic changes and expression of pro‐inflammatory molecules. Direct challenge of HepG2 with PA (200 μM) increased MD2‐TLR4 complex formation and expression of pro‐inflammatory and pro‐fibrotic genes and L6H21 pre‐treatment prevented these PA‐induced responses. Interestingly, MD2 knockout or L6H21 increased expression of the anti‐inflammatory molecule, PPARγ, in liver tissue and the liver cell line. Our results provide further evidence for the critical role of MD2 in the development of NASH and conclude that MD2 could be a potential therapeutic target for NAFLD/NASH treatment. Moreover, the small molecule MD2 inhibitor, L6H21, was an effective and selective investigative agent for future mechanistic studies of MD2.     

ARRB1 ameliorates liver ischaemia/reperfusion injury via antagonizing TRAF6‐mediated Lysine 6‐linked polyubiquitination of ASK1 in hepatocytes

Hepatic ischaemia/reperfusion (I/R) injury is a major clinical problem during liver surgical procedures, which usually lead to early transplantation failure and higher organ rejection rate, and current effective therapeutic strategies are still limited. Therefore, in‐depth exploring of the molecular mechanisms underlying liver I/R injury is key to the development of new therapeutic methods. β‐arrestins are multifunctional proteins serving as important signalling scaffolds in numerous physiopathological processes, including liver‐specific diseases. However, the role and underlying mechanism of β‐arrestins in hepatic I/R injury remain largely unknown. Here, we showed that only ARRB1, but not ARRB2, was down‐regulated during liver I/R injury. Hepatocyte‐specific overexpression of ARRB1 significantly ameliorated liver damage, as demonstrated by decreases in serum aminotransferases, hepatocellular necrosis and apoptosis, infiltrating inflammatory cells and secretion of pro‐inflammatory cytokines relative to control mice, whereas experiments with ARRB1 knockout mice gotten opposite effects. Mechanistically, ARRB1 directly interacts with ASK1 in hepatocytes and inhibits its TRAF6‐mediated Lysine 6‐linked polyubiquitination, which then prevents the activation of ASK1 and its downstream signalling pathway during hepatic I/R injury. In addition, inhibition of ASK1 remarkably abolished the disruptive effect result from ARRB1 deficiency in liver I/R injury in vivo, indicating that ASK1 was required for ARRB1 function in hepatic I/R injury. In conclusion, we proposed that ARRB1 is a novel protective regulator during liver I/R injury, and modulation of the regulatory axis between ARRB1 and ASK1 could be a novel therapeutic strategy to prevent this pathological process.     

Anti‐interleukin‐5‐neutralizing antibody attenuates caradiac injury and cadiac dysfunction by aggravating the inflammatory response in doxorubicin‐treated mice

Previous studies have demonstrated that interleukins (ILs) are closely associated with doxorubicin (DOX)‐induced cardiac injury. IL‐5 is an important member of the IL family, and this study was performed to investigate whether IL‐5 affects DOX‐induced cardiac injury and its underlying mechanisms. The cardiac IL‐5 expression was first detected and the results showed that cardiac IL‐5 levels were significantly lower in DOX‐treated mice, and IL‐5 was mainly derived from cardiac macrophage (Mø). In addition, some DOX‐treated mice received an injection of anti‐IL‐5‐neutralizing antibody (nAb), and we found that treatment with a mouse anti‐IL‐5 nAb significantly upregulated the levels of myocardial injury markers, aggravated cardiac dysfunction, increased M1 macrophage (Mø1) and decreased M2 macrophage (Mø2) differentiation, and promoted apoptotic marker expression. Furthermore, the effect of mouse IL‐5 nAb on DOX‐induced Mø differentiation and its role on mouse cardiomyocyte (MCM) cells apoptosis were detected in vitro, and the results exhibited that mouse IL‐5 nAb promoted Mø1 differentiation but inhibited Mø2 differentiation in vitro and alleviated apoptosis in MCM cells. Our results found a mouse anti‐IL‐5 nAb‐aggravated DOX‐induced cardiac injury and dysfunction by alleviating the inflammatory response and myocardial cell apoptosis.     

Inhibition of miR‐103a‐3p suppresses lipopolysaccharide‐induced sepsis and liver injury by regulating FBXW7 expression

Inflammation, apoptosis, and oxidative stress are involved in septic liver dysfunction. Herein, the role of miR‐103a‐3p/FBXW7 axis in lipopolysaccharides (LPS)‐induced septic liver injury was investigated in mice. Hematoxylin‐eosin staining was used to evaluate LPS‐induced liver injury. Quantitative real‐time polymerase chain reaction was performed to determine the expression of microRNA (miR) and messenger RNA, and western blot analysis was conducted to examine the protein levels. Dual‐luciferase reporter assay was used to confirm the binding between miR‐103a‐3p and FBXW7. Both annexin V‐fluoresceine isothiocyanate/propidium iodide staining and caspase‐3 activity were employed to determine cell apoptosis. First, miR‐103a‐3p was upregulated in the septic serum of mice and patients with sepsis, and miR‐103a‐3p was elevated in the septic liver of LPS‐induced mice. Then, interfering miR‐103a‐3p significantly decreased apoptosis by suppressing Bax expression and upregulating Bcl‐2 levels in LPS‐induced AML12 and LO2 cells, and septic liver of mice. Furthermore, inhibition of miR‐103a‐3p repressed LPS‐induced inflammation by downregulating the expression of tumor necrosis factor, interleukin 1β, and interleukin 6 in vitro and in vivo. Meanwhile, interfering miR‐103a‐3p obviously attenuated LPS‐induced overactivation of oxidation via promoting expression of antioxidative enzymes, including catalase, superoxide dismutase, and glutathione in vitro and in vivo. Moreover, FBXW7 was a target of miR‐103a‐3p, and overexpression of FBXW7 significantly ameliorated LPS‐induced septic liver injury in mice. Finally, knockdown of FBXW7 markedly reversed anti‐miR‐103a‐3p‐mediated suppression of septic liver injury in mice. In conclusion, interfering miR‐103a‐3p or overexpression of FBXW7 improved LPS‐induced septic liver injury by suppressing apoptosis, inflammation, and oxidative reaction.     

IL‐6 Trans‐Signaling Plays Important Protective Roles in Acute Liver Injury Induced by Acetaminophen in Mice

Our study was undertaken to evaluate the important role of interleukin‐6 (IL‐6) trans‐signaling in acetaminophen (AAP)‐induced liver injury. A soluble gp130 protein (sgp130Fc) exclusively inhibits IL‐6 trans‐signaling, whereas an IL‐6/soluble IL‐6 receptor (sIL‐6R) fusion protein (hyper‐IL‐6) mimics IL‐6 trans‐signaling. Using these tools, we investigated the role of IL‐6 trans‐signaling in AAP‐induced liver injury. Blockade of IL‐6 trans‐signaling during AAP‐induced liver injury remarkably increased the levels of serum aspartate aminotransferase and alanine aminotransferase; lowered the level of serum sIL‐6R; aggravated liver injury; inhibited the expression of phosphorylation of STAT3 (pSTAT3), proliferating cell nuclear antigen, vascular endothelial growth factor, and glycogen synthesis; and induced the expression of Caspase3, cytochrome P450 2E1 (CYP2E1), and hepatocyte apoptosis in the liver of mice. In summary, our study suggested that IL‐6 trans‐signaling plays important protective roles by regulating the hepatocyte proliferation and apoptosis, angiogenesis, CYP2E1 expression, and glycogen metabolism during AAP‐induced liver injury in mice.     

Synthesis and Antioxidant Activity of 3‐(Pyridin‐2‐ylmethyl)‐1,3‐thiazinan(thiazolidin)‐4‐ones

The antioxidant properties of two series of thiazolidinones and thiazinanones were reported. The novel six‐membered thiazinanones were synthesized from the efficient multicomponent reaction of 2‐picolylamine (2‐aminomethylpyridine), arenaldehydes, and the 3‐mercaptopropionic acid in moderate to excellent yields. These novel compounds were fully identified and characterized by NMR and GC‐MS techniques. In vitro antioxidant activities of all compounds were evaluated by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2′‐azinobis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) tests. The antioxidant assays of thiobarbituric acid reactive species and total thiol content levels in the cerebral cortex and liver of rats were also performed. Thiazinanone 5a showed the best radical scavenging activity in DPPH and ABTS tests, as well as reduced lipid peroxidation and increased total thiol group in biological systems. Altogether, the results may be considered a good starting point for the discovery of a new radical scavenger.     

Exosomes derived from miR‐181‐5p‐modified adipose‐derived mesenchymal stem cells prevent liver fibrosis via autophagy activation

Proliferating hepatic stellate cells (HSCs) respond to liver damage by secreting collagens that form fibrous scar tissue, which can lead to cirrhosis if in appropriately regulated. Advancement of microRNA (miRNA) hepatic therapies has been hampered by difficulties in delivering miRNA to damaged tissue. However, exosomes secreted by adipose‐derived mesenchymal stem cells (ADSCs) can be exploited to deliver miRNAs to HSCs. ADSCs were engineered to overexpress miRNA‐181‐5p (miR‐181‐5p‐ADSCs) to selectively home exosomes to mouse hepatic stellate (HST‐T6) cells or a CCl4‐induced liver fibrosis murine model and compared with non‐targeting control Caenorhabditis elegans miR‐67 (cel‐miR‐67)‐ADSCs. In vitro analysis confirmed that the transfer of miR‐181‐5p from miR‐181‐5p‐ADSCs occurred via secreted exosomal uptake. Exosomes were visualized in HST‐T6 cells using cyc3‐labelled pre‐miRNA‐transfected ADSCs with/without the exosomal inhibitor, GW4869. The effects of miRNA‐181‐5p overexpression on the fibrosis associated STAT3/Bcl‐2/Beclin 1 pathway and components of the extracellular matrix were assessed. Exosomes from miR181‐5p‐ADSCs down‐regulated Stat3 and Bcl‐2 and activated autophagy in the HST‐T6 cells. Furthermore, the up‐regulated expression of fibrotic genes in HST‐T6 cells induced by TGF‐β1 was repressed following the addition of isolated miR181‐5p‐ADSC exosomes compared with miR‐67‐ADSCexosomes. Exosome therapy attenuated liver injury and significantly down‐regulated collagen I, vimentin, α‐SMA and fibronectin in liver, compared with controls. Taken together, the effective anti‐fibrotic function of engineered ADSCs is able to selectively transfer miR‐181‐5p to damaged liver cells and will pave the way for the use of exosome‐ADSCs for therapeutic delivery of miRNA targeting liver disease.     

Aging aggravated liver ischemia and reperfusion injury by promoting STING‐mediated NLRP3 activation in macrophages

Although aggravated liver injury has been reported in aged livers post‐ischemia and reperfusion (IR), the underlying mechanism of innate immune activation of aged macrophages is not well understood. Here, we investigated whether and how Stimulator of interferon genes (STING) signaling regulated macrophage proinflammatory activation and liver IR injury. Mice were subjected to hepatic IR in vivo. Macrophages isolated from IR‐stressed livers and bone marrow‐derived macrophages (BMDMs) from young and aged mice were used for in vitro studies. Enhanced nucleotide‐binding domain and leucine‐rich repeat containing protein 3 (NLRP3) activation was found in both livers and macrophages of aged mice post‐IR. NLRP3 knockdown in macrophages inhibited intrahepatic inflammation and liver injury in both young and aged mice. Interestingly, enhanced activation of the STING/ TANK‐binding kinase 1 (TBK1) signaling pathway was observed in aged macrophages post‐IR and mitochondria DNA (mtDNA) stimulation. STING suppression blocked over‐activation of NLRP3 signaling and excessive secretion of proinflammatory cytokines/chemokines in the mtDNA‐stimulated BMDMs from aged mice. More importantly, STING knockdown in macrophages abrogated the detrimental role of aging in aggravating liver IR injury and intrahepatic inflammation. Finally, peripheral blood from the recipients undergoing liver transplantation was collected and analyzed. The results showed that the elderly recipients had much higher levels of TNF‐α, IL‐6, IL‐1β, and IL‐18 post‐transplantation, indicating increased NLRP3 activation in lR‐stressed livers of elderly recipients. In summary, our study demonstrated that the STING‐NLRP3 axis was critical for the proinflammatory response of aged macrophages and would be a novel therapeutic target to reduce IR injury in elderly patients.     

Z‐FA.FMK activates duodenal epithelial cell proliferation through oxidative stress,NF‐κB and IL‐1β in d‐GalN/TNF‐α‐administered mice

This study was designed to evaluate the effect of Z‐FA.FMK (benzyloxycarbonyl‐l ‐phenylalanyl‐alanine‐fluoromethylketone), a pharmacological inhibitor of cathepsin B, on the proliferation of duodenal mucosal epithelial cells and the cellular system that controls this mechanism in these cells in vivo. For this investigation, BALB/c male mice were divided into four groups. The first group received physiological saline, the second group was administered Z‐FA.FMK, the third group received d ‐GalN (d ‐galactosamine) and TNF‐α (tumour necrosis factor‐α) and the fourth group was given both d ‐GalN/TNF‐α and Z‐FA.FMK. When d ‐GalN/TNF‐α was administered alone, we observed an increase in IL‐1β‐positive and active NF‐κB‐positive duodenal epithelial cells, a decrease in PCNA (proliferative cell nuclear antigen)‐positive duodenal epithelial cells and an increase in degenerative changes in duodenum. On the other hand, Z‐FA.FMK pretreatment inhibited all of these changes. Furthermore, lipid peroxidation, protein carbonyl and collagen levels were increased, glutathione level and superoxide dismutase activity were decreased, while there was no change in catalase activity by d ‐GalN/TNF‐α injection. On the contrary, the Z‐FA.FMK pretreatment before d ‐GalN/TNF‐α blocked these effects. Based on these findings, we suggest that Z‐FA.FMK might act as a proliferative mediator which is controlled by IL‐1β through NF‐κB and oxidative stress in duodenal epithelial cells of d ‐GalN/TNF‐α‐administered mice.     

Tumour necrosis factor‐α promotes liver ischaemia‐reperfusion injury through the PGC‐1α/Mfn2 pathway

Tumour necrosis factor (TNF)‐α has been considered to induce ischaemia‐reperfusion injury (IRI) of liver which is characterized by energy dysmetabolism. Peroxisome proliferator–activated receptor‐γ co‐activator (PGC)‐1α and mitofusion2 (Mfn2) are reported to be involved in the regulation of mitochondrial function. However, whether PGC‐1α and Mfn2 form a pathway that mediates liver IRI, and if so, what the underlying involvement is in that pathway remain unclear. In this study, L02 cells administered recombinant human TNF‐α had increased TNF‐α levels and resulted in down‐regulation of PGC‐1α and Mfn2 in a rat liver IRI model. This was associated with hepatic mitochondrial swelling, decreased adenosine triphosphate (ATP) production, and increased levels of reactive oxygen species (ROS) and alanine aminotransferase (ALT) activity as well as cell apoptosis. Inhibition of TNF‐α by neutralizing antibody reversed PGC‐1α and Mfn2 expression, and decreased hepatic injury and cell apoptosis both in cell culture and in animals. Treatment by rosiglitazone sustained PGC‐1α and Mfn2 expression both in IR livers, and L02 cells treated with TNF‐α as indicated by increased hepatic mitochondrial integrity and ATP production, reduced ROS and ALT activity as well as decreased cell apoptosis. Overexpression of Mfn2 by lentiviral‐Mfn2 transfection decreased hepatic injury in IR livers and L02 cells treated with TNF‐α. However, there was no up‐regulation of PGC‐1α. These findings suggest that PGC‐1α and Mfn2 constitute a regulatory pathway, and play a critical role in TNF‐α‐induced hepatic IRI. Inhibition of the TNF‐α or PGC‐1α/Mfn2 pathways may represent novel therapeutic interventions for hepatic IRI.