Clodronate, an inhibitor of the vesicular nucleotide transporter, ameliorates steatohepatitis and acute liver injury

AbstractThe vesicular nucleotide transporter (VNUT) is responsible for the vesicular storage and release of ATP from various ATP-secreting cells, and it plays an essential role in purinergic signaling. Although extracellular ATP and its degradation products are known to mediate various inflammatory responses via purinoceptors, whether vesicular ATP release affects steatohepatitis and acute liver injury is far less understood. In the present study, we investigated the effects of clodronate, a potent and selective VNUT inhibitor, on acute and chronic liver inflammation in mice. In a model of methionine/choline-deficient diet-induced non-alcoholic steatohepatitis (NASH), the administration of clodronate reduced hepatic inflammation, fibrosis, and triglyceride accumulation. Clodronate also protected mice against high-fat/high-cholesterol diet-induced steatohepatitis. Moreover, prophylactic administration of clodronate prevented d-galactosamine and lipopolysaccharide-induced acute liver injury by reducing inflammatory cytokines and hepatocellular apoptosis. In vitro, clodronate inhibited glucose-induced vesicular ATP release mediated by VNUT and reduced the intracellular level and secretion of triglycerides in isolated hepatocytes. These results suggest that VNUT-dependent vesicular ATP release plays a crucial role in the recruitment of immune cells, cytokine production, and the aggravation of steatosis in the liver. Pharmacological inhibition of VNUT may provide therapeutic benefits in liver inflammatory disorders, including NASH and acute toxin-induced injury.

Download Full-text

CD36 deficiency ameliorates drug-induced acute liver injury in mice

Molecular Medicine ◽

10.1186/s10020-021-00325-z ◽

2021 ◽

Vol 27 (1) ◽

Author(s):

Chen Zhang ◽

Xiao Shi ◽

Zhongping Su ◽

Chao Hu ◽

Xianmin Mu ◽

...

Keyword(s):

Liver Injury ◽

Western Blot ◽

Kinase Inhibitor ◽

Inflammatory Responses ◽

Acute Liver Injury ◽

Protein Adducts ◽

Sterile Inflammation ◽

Inflammatory Factor ◽

Cd36 Deficiency ◽

Significant Difference

Abstract Background Acetaminophen (APAP) overdose causes hepatotoxicity and even acute liver failure. Recent studies indicate that sterile inflammation and innate immune cells may play important roles in damage-induced hepatocytes regeneration and liver repair. The scavenger receptor CD36 has its crucial functions in sterile inflammation. However, the roles of CD36 in APAP induced acute liver injury remain unclear and warrant further investigation. Methods WT C57BL/6 J and CD36−/− mice were intraperitoneally injected with APAP (300 mg/kg) after fasting for 16 h. Liver injury was evaluated by serum alanine aminotransferase (ALT) level and liver tissue hematoxylin and eosin (H&E) staining. Liver inflammatory factor expression was determined by real-time polymerase chain reaction (PCR). The protein adducts forming from the metabolite of APAP and the metabolism enzyme cytochrome P450 2E1 (CYP2E1) levels were measured by Western blot. Liver infiltrating macrophages and neutrophils were characterized by flow cytometry. RNA sequencing and Western blot were used to evaluate the effect of damage-associated molecular patterns (DAMP) molecule high mobility group B1 (HMGB1) on WT and CD36−/− macrophages. Moreover, PP2, a Src kinase inhibitor, blocking CD36 signaling, was applied in APAP model. Results The expression of CD36 was increased in the liver of mice after APAP treatment. Compared with WT mice, APAP treated CD36−/− mice show less liver injury. There was no significant difference in APAP protein adducts and CYP2E1 expression between these two strains. However, reduced pro-inflammatory factor mRNA expression and serum IL-1β level were observed in APAP treated CD36−/− mice as well as infiltrating macrophages and neutrophils. Moreover, CD36 deficiency impaired the activation of c-Jun N-terminal kinase (JNK) caused by APAP. Interestingly, the lack of CD36 reduced the activation of extracellular regulated protein kinases (Erk) and v-akt murine thymoma viral oncogene homolog (Akt) induced by HMGB1. RNA transcription sequencing data indicated that HMGB1 has a different effect on WT and CD36−/− macrophages. Furthermore, treatment with PP2 attenuated APAP induced mouse liver injury. Conclusion Our data demonstrated that CD36 deficiency ameliorated APAP-induced acute liver injury and inflammatory responses by decreasing JNK activation. CD36 might serve as a new target to reduce acute liver injury.

Download Full-text

Characterization and Evaluation of HGF-Loaded PLGA Nanoparticles in a CCl4-Induced Acute Liver Injury Mouse Model

Journal of Nanomaterials ◽

10.1155/2019/7936143 ◽

2019 ◽

Vol 2019 ◽

pp. 1-13

Author(s):

Chuxi Lin ◽

Xueer Wang ◽

Nuyun Liu ◽

Qing Peng ◽

Yang Li ◽

...

Keyword(s):

Liver Injury ◽

Mouse Model ◽

Acute Liver Injury ◽

Redox Homeostasis ◽

Plga Nanoparticles ◽

Physical Characteristics ◽

Sod Activity ◽

Therapeutic Benefits ◽

Antioxidant Proteins ◽

Drug Free

Liver injury can be caused by various harmful factors since the liver is considered the key organ for detoxifying endogenous and exogenous substances. Hepatocyte growth factor (HGF) can regulate redox homeostasis through the expression of antioxidant proteins when the liver is under injury. However, HGF is easily degraded. In this study, we produced three kinds of HGF-loaded poly(lactic-co-glycolic) acid (PLGA) nanoparticles with an initial addition of 2 μg HGF (NPs-HGF-2 μg), 4 μg HGF (NPs-HGF-4 μg), and drug-free nanoparticles (NPs) using the W/O/W emulsion-solvent evaporation method in accordance with our patent. The morphology and physical characteristics were analyzed, and effects of HGF-loaded PLGA nanoparticles on a CCl4-induced acute liver injury mouse model were investigated and compared with HGF solutions. We observed that the morphology and the physical characteristics of the nanoparticles were almost the same, with similar sizes, polydispersity, and zeta potential. HGF-loaded PLGA nanoparticles maintained higher HGF concentrations for a longer period of time in blood and liver tissues. HGF-loaded PLGA nanoparticles increased the SOD activity and GPX levels, decreased the MDA levels in the liver, reduced the necrotic areas of the liver, and decreased the levels of AST, ALT, ALP, T-BIL, BUN, and Scr in blood. In conclusion, our technique for preparing HGF-loaded PLGA nanoparticles was stable and the products were of good quality. HGF-loaded PLGA nanoparticles could provide greater therapeutic benefits on CCl4-induced acute liver injury, including antilipid peroxidation and a reduction in indicator enzymes of liver injury.

Download Full-text

S100A6 Promotes Inflammation and Infiltration of Mononuclear/Macrophages via the p-P38 and p-JNK Pathways in Acute Liver Injury

10.21203/rs.3.rs-1161048/v1 ◽

2021 ◽

Author(s):

He Tong ◽

Li Wang ◽

Kefan Zhang ◽

Jing Shi ◽

yongshuai Wu ◽

...

Keyword(s):

Liver Injury ◽

Inflammatory Response ◽

Inflammatory Responses ◽

Acute Liver Injury ◽

S100 Protein ◽

Inflammatory Cells ◽

Liver Cells ◽

Danger Signal ◽

Tnf Α

Abstract BackgroundThe phagocytic S100 protein, which mediates inflammatory responses and recruits inflammatory cells to sites of tissue damage, has long been known to be expressed in cells of myeloid origin. S100A6 belongs to the A group of the S100 protein family of Ca2+-binding proteins. Currently, the mechanism by which S100A6 mediates the inflammatory response and recruits inflammatory cells to the tissue injury site is unknown.MethodsA mouse model of carbon tetrachloride (CCl4)-induced acute liver injury (ALI) was established, and the transcriptomes of postinjury 2d and 5d liver tissues were sequenced. Enzyme-linked immunosorbent assay was used to determine the expression of inflammatory factors (TNF-α, IL-1β, IL-6, and IL-8) in the supernatant of the liver. Immunohistochemical analysis confirmed the expression of S100A6 in the liver cells. In vitro experiments proved the pro-inflammatory function of S100A6, and western blotting (WB) showed that the pathways were activated. The transwell experiment showed the infiltration of mononuclear/macrophages.ResultsWe found that S100A6 is highly expressed in liver cells during the most severe period of ALI, suggesting that it acts as an endogenous danger signal and has a pro-inflammatory function. In vitro, the mouse S100A6 recombinant protein was used to stimulate liver Kupffer cells to promote the secretion of TNF-α, IL-1β, IL-6, and IL-8. Further mechanistic experiments revealed that S100A6 acts as an endogenous danger signal to activate p-P38 and p-JNK downstream of the TLR4 and P65 pathways. Similarly, transcriptome data showed that S100A6 can activate the inflammatory response in Kuffer cells. WB revealed that S100A6 had no significant effect on cell apoptosis. To continue to explore the mechanism of monocyte/macrophage infiltration, we found that TNF-α stimulates liver cells as the main source of CCL2. TNF-α can initiate the p-P38 and p-JNK pathways of liver cells to produce CCL2, thereby recruiting the infiltration of mononuclear/macrophages. ConclusionsTaken together, S100A6 is an endogenous danger signal that mediates inflammatory responses and recruits inflammatory cells to sites of tissue damage.

Download Full-text

The protein tyrosine kinase SYK regulates the alternative p38 activation in liver during acute liver inflammation

Scientific Reports ◽

10.1038/s41598-019-54335-3 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Bo-Ram Bang ◽

Kyung Ho Han ◽

Goo-Young Seo ◽

Michael Croft ◽

Young Jun Kang

Keyword(s):

Cell Death ◽

Liver Injury ◽

Host Defense ◽

Protein Tyrosine Kinase ◽

Inflammatory Responses ◽

Acute Liver Injury ◽

Critical Role ◽

Liver Inflammation ◽

Hepatocyte Death

AbstractTwo distinct p38 signaling pathways, classical and alternative, have been identified to regulate inflammatory responses in host defense and disease development. The role of alternative p38 activation in liver inflammation is elusive, while classical p38 signaling in hepatocytes plays a role in regulating the induction of cell death in autoimmune-mediated acute liver injury. In this study, we found that a mutation of alternative p38 in mice augmented the severity of acute liver inflammation. Moreover, TNF-induced hepatocyte death was augmented by a mutation of alternative p38, suggesting that alternative p38 signaling in hepatocytes contributed more significantly to the pathology of acute liver injury. Furthermore, SYK-Vav-1 signaling regulates alternative p38 activation and the downregulation of cell death in hepatocytes. Therefore, it is suggested that alternative p38 signaling in the liver plays a critical role in the induction and subsequent pathological changes of acute liver injury. Collectively, our results imply that p38 signaling in hepatocytes plays a crucial role to prevent excessive liver injury by regulating the induction of cell death and inflammation.

Download Full-text

ATP-release drives inflammation with lysophosphatidylcholine

10.1101/2020.12.25.424382 ◽

2020 ◽

Author(s):

Sana Ismaeel ◽

Ayub Qadri

Keyword(s):

Inflammatory Cytokines ◽

Inflammatory Responses ◽

Purinergic Signaling ◽

Low Density Lipoprotein ◽

Neuronal Cells ◽

Atp Release ◽

Density Lipoprotein ◽

Independent Manner ◽

Caspase 1

AbstractLysophosphatidylcholine (LPC), a dominant lipid component of oxidized low-density lipoprotein, plays a major role in inflammation associated with atherosclerosis and neurodegenerative disorders. It activates inflammatory responses from macrophages, neuronal cells and endothelial cells. However, the exact mechanism by which LPC promotes inflammation remains incompletely understood. Here, we show that the production of inflammatory cytokines and cytotoxicity with LPC are both critically dependent on its ability to bring about release of ATP from cells. The induction of caspase-1-mediated IL-1β-release with LPC from TLR-primed macrophages and neuronal cells is reduced in presence of ATP-hydrolyzing enzyme, apyrase and the inhibitors of purinergic signaling. ATP released from LPC-treated cells also promotes an IL-12p70hi, low phagocytic and poorly co-stimulatory phenotype in macrophages in a caspase-1 – independent manner. Treatment with apyrase reduces production of inflammatory cytokines with LPC in vivo. These findings reveal a previously unappreciated pathway for generation of inflammatory responses with LPC, and these have significant implications for therapeutic intervention in chronic inflammatory disorders promoted by this lipid.

Download Full-text

Probenecid affects sarcoplasmic reticulum Ca2+ release and depresses contractile activation in mouse skeletal muscle

The Journal of General Physiology ◽

10.1085/jgp.2021ecc23 ◽

2021 ◽

Vol 154 (9) ◽

Author(s):

Francisco Jaque-Fernandez ◽

Bruno Allard ◽

Laloe Monteiro ◽

Aude Lafoux ◽

Corinne Huchet ◽

...

Keyword(s):

Skeletal Muscle ◽

Sarcoplasmic Reticulum ◽

Extracellular Space ◽

Purinergic Signaling ◽

Muscle Fibers ◽

Atp Release ◽

Extracellular Medium ◽

Mouse Muscle ◽

Therapeutic Benefits ◽

Ec Coupling

Pannexins are plasma membrane heptameric channels mediating ATP release from the cytosol to the extracellular space. Skeletal muscle activity is associated with Pannexin 1 (Panx1) channels activation, ATP release out to the extracellular space and subsequent activation of purinergic signaling pathways. In agreement, recent evidence has shown molecular and functional interactions between Panx1 and the excitation–contraction (EC) coupling machinery of skeletal muscle. In this framework, we tested whether pharmacological effectors of Panx1 affect EC coupling in differentiated muscle fibers. Using confocal detection of cytosolic Ca2+ in voltage-clamped mouse muscle fibers, we found that the Panx1 blocker probenecid (1 mM) affects intracellular Ca2+ handling and EC coupling: acute application of probenecid generates a rise in resting Ca2+ that also occurs in nominally Ca2+-free extracellular medium. This effect is associated with a reduction of Ca2+ release through the sarcoplasmic reticulum (SR) Ca2+ channel RYR1. The effect of probenecid persists with time, with muscle fibers incubated for 30 min in the presence of the drug exhibiting a 40% reduction in peak SR Ca2+ release. Under the same conditions, the other Panx1 blocker carbenoxolone (50 µM) produced a 70% reduction in peak SR Ca2+ release. Application of probenecid on electrically stimulated whole mouse muscle induced a slight rise in resting tension and a >50% reduction of tetanic force after 30 min of incubation. Our results provide further support for the strong links between Panx1 function and EC coupling. Because probenecid is used both in the clinic for several types of therapeutic benefits and as a hiding agent for doping in sport, our results question whether potential adverse muscular effects may have, so far, been overlooked.

Download Full-text

IL-22 ameliorates LPS-induced acute liver injury by autophagy activation through ATF4-ATG7 signaling

Cell Death and Disease ◽

10.1038/s41419-020-03176-4 ◽

2020 ◽

Vol 11 (11) ◽

Author(s):

Lujing Shao ◽

Xi Xiong ◽

Yucai Zhang ◽

Huijie Miao ◽

Yuqian Ren ◽

...

Keyword(s):

Liver Injury ◽

Inflammatory Responses ◽

Acute Liver Injury ◽

Mrna Levels ◽

Protective Effects ◽

Activating Transcription Factor 4 ◽

Pre Treatment ◽

Underlying Mechanisms

Abstract Uncontrollable inflammatory response acts as a driver of sepsis-associated liver injury (SALI). IL-22 plays an important role in regulating inflammatory responses, but its role in SALI remains unknown. The aim of the study was to assess the association of serum IL-22 with SALI in pediatric patients and to enclose the underlying mechanisms of IL-22 involved in lipopolysaccharide (LPS) - induced acute liver injury (ALI) in mice. Serum IL-22 levels in patients with SALI were significantly lower than in septic patients without liver injury, and the area under receiver operating characteristic (ROC) curve of IL-22 for discriminating SALI was 0.765 (95% CI: 0.593–0.937). Pre-administration of recombinant murine IL-22 alleviated LPS-induced ALI in mice, and serum IL-6 levels and the mRNA levels of TNF-α, IL-1β, and IL-6 in livers were decreased in response to IL-22 pre-treatment in mice. More importantly, IL-22 pre-treatment activated hepatic autophagy mediated by activating transcription factor 4 (ATF4)-autophagy-related gene 7 (ATG7) signaling in vivo and in vitro in response to LPS administration. Moreover, knockdown of ATF4 in mice aggravated LPS-induced ALI, which was associated with suppressed ATG7-related autophagy. In addition, the protective effects of IL-22 on LPS-induced ALI was partially blocked by ATF4 knockdown, which was associated with lower expression of LC3II/I in the livers of ATF4 knockdown (HT or Atf4+/−) mice compared with wild-type mice (WT or Atf4+/+) mice. In conclusion, low serum IL-22 level is associated with SALI occurrence, and IL-22 pre-administration activates autophagy in hepatocytes and protects mice against LPS-induced ALI partially related to ATF4-ATG7 signaling pathway.

Download Full-text

Short-form Ron receptor is required for normal IFN-γ production in concanavalin A-induced acute liver injury

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00134.2006 ◽

2007 ◽

Vol 292 (1) ◽

pp. G253-G261 ◽

Cited By ~ 7

Author(s):

Cynthia C. Wetzel ◽

Mike A. Leonis ◽

Arlene Dent ◽

Meredith A. Olson ◽

Angela M. Longmeier ◽

...

Keyword(s):

Liver Injury ◽

Concanavalin A ◽

Inflammatory Responses ◽

Acute Liver Injury ◽

Ex Vivo ◽

Short Form ◽

Cell Receptor ◽

Ron Receptor ◽

Ifn Γ

Abrogation of Ron receptor tyrosine kinase function results in defects in macrophage activation and dysregulated acute inflammatory responses in vivo. Several naturally occurring constitutively active alternative forms of Ron have been identified, including from primary human tumors and tumor cell lines. One of these alternative forms, short-form (SF) Ron, is generated from an alternative start site in intron 10 of the Ron gene that eliminates most of the extracellular portion of the receptor and is overexpressed in several human cancers. To test the physiological significance of SF-Ron in vivo, mice were generated that solely express the full-length form of Ron (FL-Ron). Our results show that elimination of the capacity to express SF-Ron in vivo leads to augmented production of IFN-γ from splenocytes following stimulation ex vivo with either concanavalin A or anti-CD3/T cell receptor monoclonal antibody. Moreover, in a concanavalin A-induced murine model of acute liver injury, FL-Ron mice have increased production of serum INF-γ and serum alanine aminotransferase levels and worsened liver histology and overall survival compared with wild-type control mice. Taken together, these results suggest for the first time that SF-Ron impacts the progression of inflammatory immune responses in vivo and further support a role for the Ron receptor and its various forms in liver pathophysiology.

Download Full-text