Kupffer Cell Activation Research Articles

Hyperglycemia aggravates acute liver injury by promoting liver‐resident macrophage NLRP3 inflammasome activation via the inhibition of AMPK/mTOR‐mediated autophagy induction

Although the detrimental effects of diabetes mellitus/hyperglycemia have been observed in many liver disease models, the function and mechanism of hyperglycemia regulating liver‐resident macrophages, Kupffer cells (KCs), in thioacetamide (TAA)‐induced liver injury remain largely unknown. In this study, we evaluated the role of hyperglycemia in regulating NOD‐like receptor family pyrin domain‐containing 3 protein (NLRP3) inflammasome activation by inhibiting autophagy induction in KCs in the TAA‐induced liver injury model. Type I diabetes/hyperglycemia was induced by streptozotocin treatment. Compared with the control group, hyperglycemic mice exhibited a significant increase in intrahepatic inflammation and liver injury. Enhanced NLRP3 inflammasome activation was detected in KCs from hyperglycemic mice, as shown by increased gene induction and protein levels of NLRP3, cleaved caspase‐1, apoptosis‐associated speck‐like protein containing a caspase recruitment domain and interleukin‐1β, compared with control mice. NLRP3 inhibition by its antagonist CY‐09 effectively suppressed inflammasome activation in KCs and attenuated liver injury in hyperglycemic mice. Furthermore, inhibited autophagy activation was revealed by transmission electron microscope detection, decreased LC3B protein expression and p‐62 protein degradation in KCs isolated from TAA‐stressed hyperglycemic mice. Interestingly, inhibited 5′ AMP‐activated protein kinase (AMPK) but enhanced mammalian target of rapamycin (mTOR) activation was found in KCs from TAA‐stressed hyperglycemic mice. AMPK activation by its agonist 5‐aminoimidazole‐4‐carboxamide ribonucleotide (AICAR) or mTOR signaling knockdown by small interfering RNA restored autophagy activation, and subsequently, inhibited NLRP3 inflammasome activation in KCs, leading to ultimately reduced TAA‐induced liver injury in the hyperglycemic mice. Our findings demonstrated that hyperglycemia aggravated TAA‐induced acute liver injury by promoting liver‐resident macrophage NLRP3 inflammasome activation via inhibiting AMPK/mTOR‐mediated autophagy. This study provided a novel target for prevention of toxin‐induced acute liver injury under hyperglycemia.

Kupffer Cells Mediate Systemic Antifungal Immunity

Patients with liver dysfunction have increased susceptibility to fungal infections. A recently published article (Sun et al.) describes the potential mechanism underlying this association, which maps to the antifungal activity of liver-resident Kupffer cells. This research highlights the importance of understanding tissue-specific immune responses in disease pathogenesis.

Rat multicellular 3D liver microtissues to explore TGF-β1 induced effects

Chronic liver damage can lead to fibrosis, encompassing hepatocellular injury, activation of Kupffer cells (KC), and activation of hepatic stellate cells (HSC). Inflammation and TGF-β1 are known mediators in the liver fibrosis adverse outcome pathway (AOP). The aim of this project was to develop a suitable rodent cell culture model for the investigation of key events involved in the development of liver fibrosis, specifically the responses to pathophysiological stimuli such as TGF-β1 and LPS-triggered inflammation.We optimized a single step protocol to purify rat primary hepatocytes (Hep), HSC and KC cells to generate 3D co-cultures based on the hanging drop method.This primary multicellular model responded to the profibrotic cytokine TGF-β1 (1 ng/mL) with signs of hepatocellular damage, inflammation and ultimately HSC activation (increase in αSMA expression). LPS elicited an inflammatory response characterized by increased expression of cytokines.3D-monocultures comprising only Hep displayed different responses, underlying that parenchymal and non-parenchymal cells need to be present in the system to recapitulate fibrosis. The data also suggest that pre-activated HSC may reverse to a quiescent phenotype in 3D, probably due to the more physiological conditions.

The Role of Gut-Derived Microbial Antigens on Liver Fibrosis Initiation and Progression.

Intestinal dysbiosis has recently become known as an important driver of gastrointestinal and liver disease. It remains poorly understood, however, how gastrointestinal microbes bypass the intestinal mucosa and enter systemic circulation to enact an inflammatory immune response. In the context of chronic liver disease (CLD), insults that drive hepatic inflammation and fibrogenesis (alcohol, fat) can drastically increase intestinal permeability, hence flooding the liver with gut-derived microbiota. Consequently, this may result in exacerbated liver inflammation and fibrosis through activation of liver-resident Kupffer and stellate cells by bacterial, viral, and fungal antigens transported to the liver via the portal vein. This review summarizes the current understanding of microbial translocation in CLD, the cell-specific hepatic response to intestinal antigens, and how this drives the development and progression of hepatic inflammation and fibrosis. Further, we reviewed current and future therapies targeting intestinal permeability and the associated, potentially harmful anti-microbial immune response with respect to their potential in terms of limiting the development and progression of liver fibrosis and end-stage cirrhosis.

Aflatoxin B1 enhances pyroptosis of hepatocytes and activation of Kupffer cells to promote liver inflammatory injury via dephosphorylation of cyclooxygenase-2: an in vitro, ex vivo and in vivo study.

Aflatoxin B1 (AFB1), a food contaminant derived from Aspergillus fungi, has been reported to cause hepatic immunotoxicity via inflammatory infiltration and cytokines release. As a pro-inflammatory factor, cyclooxygenase-2 (COX-2) is widely involved in liver inflammation induced by xenobiotics. However, the mechanism by which AFB1-induced COX-2 regulates liver inflammatory injury via hepatocytes-Kupffer cells (KCs) crosstalk remains unclear and requires further elucidation. Here, we established a COX-2 upregulated model with AFB1 treatment in vivo (C57BL/6 mice, 1mg/kg body weight, i.g, 4weeks) and in vitro (human liver HepaRG cells, 1μM for 24h). In vivo, AFB1-treated mice exhibited NLRP3 inflammasome activation, inflammatory infiltration, and increased recruitment of KCs. In vitro, dephosphorylated COX-2 by protein phosphatase 2A (PP2A)-B55δ promoted NLRP3 inflammasome activation, including mitochondrial translocation of NLRP3, caspase 1 cleavage, and IL-1β release. Moreover, phosphorylated COX-2 at serine 601 (p-COX-2Ser601) underwent endoplasmic reticulum (ER) retention for proteasome degradation. Furthermore, pyroptosis and inflammatory response induced by AFB1 were relieved with COX-2 genetic (siPTGS2) intervention or pharmaceutic (celecoxib, 30mg/kg body weight, i.g, 4weeks) inhibition of COX-2 via NLRP3 inflammasome suppression in vivo and in vitro. Ex vivo, in a co-culture system with murine primary hepatocytes and KCs, activated KCs induced by damaged signals from pyroptotic hepatocytes, formed a feedback loop to amplify NLRP3-dependent pyroptosis of hepatocytes via pro-inflammatory signaling, leading to liver inflammatory injury. Taken together, our data suggest a novel mechanism that protein quality control of COX-2 determines the intracellular distribution and activation of NLRP3 inflammasome, which promotes liver inflammatory injury via hepatocytes-KCs crosstalk.

Inhibitory effects of diallyl sulfide on the activation of Kupffer cell in lipopolysaccharide/d-galactosamine-induced acute liver injury in mice

Abstract Diallyl sulfide (DAS) is an effective bioactive organosulfur compound extracted from garlic. This study aimed to explore whether the protective effect of DAS on lipopolysaccharide (LPS)/ d -galactosamine ( d -GalN) induced acute liver injury was associated with the regulation of Kupffer cell (KC) activation. The results indicated that DAS administration protected mice from LPS/D-GalN-induced histopathological damage and serum aminotransferase elevation and also showed more pronounced beneficial effects than GdCl3 administration. The F4/80+ or CD11b+ KC immunohistochemistry results showed that DAS administration suppressed LPS/D-GalN-induced KC activation. DAS administration also suppressed LPS/D-GalN-triggered production of TNF-α, IL-1β, MCP-1 and NO in the liver or serum, which was in line with the mRNA expression of TNF-α, IL-1β, IL-6, MCP-1 and iNOS in the liver. Taken together, these findings reveal that the protective effects of DAS on LPS/D-GalN-induced acute liver injury may be achieved by inhibiting the activation of KC, thereby suppressing the secretion of various proinflammatory mediators.

Ceria Nanoparticles Meet Hepatic Ischemia-Reperfusion Injury: The Perfect Imperfection.

The mononuclear phagocyte system (MPS, e.g., liver, spleen) is often treated as a "blackbox" by nanoresearchers in translating nanomedicines. Often, most of the injected nanomaterials are sequestered by the MPS, preventing their delivery to the desired disease areas. Here, this imperfection is exploited by applying nano-antioxidants with preferential liver uptake to directly prevent hepatic ischemia-reperfusion injury (IRI), which is a reactive oxygen species (ROS)-related disease. Ceria nanoparticles (NPs) are selected as a representative nano-antioxidant and the detailed mechanism of preventing IRI is investigated. It is found that ceria NPs effectively alleviate the clinical symptoms of hepatic IRI by scavenging ROS, inhibiting activation of Kupffer cells and monocyte/macrophage cells. The released pro-inflammatory cytokines are then significantly reduced and the recruitment and infiltration of neutrophils are minimized, which suppress subsequent inflammatory reaction involved in the liver. The protective effect of nano-antioxidants against hepatic IRI in living animals and the revealed mechanism herein suggests their future use for the treatment of hepatic IRI in the clinic.

Exogenous PP2A inhibitor exacerbates the progression of nonalcoholic fatty liver disease via NOX2-dependent activation of miR21.

Nonalcoholic fatty liver disease (NAFLD) is an emerging global pandemic. Though significant progress has been made in unraveling the pathophysiology of the disease, the role of protein phosphatase 2A (PP2A) and its subsequent inhibition by environmental and genetic factors in NAFLD pathophysiology remains unclear. The present report tests the hypothesis that an exogenous PP2A inhibitor leads to hepatic inflammation and fibrogenesis via an NADPH oxidase 2 (NOX2)-dependent pathway in NAFLD. Results showed that microcystin (MC) administration, a potent PP2A inhibitor found in environmental exposure, led to an exacerbation of NAFLD pathology with increased CD68 immunoreactivity, the release of proinflammatory cytokines, and stellate cell activation, a process that was attenuated in mice that lacked the p47phox gene and miR21 knockout mice. Mechanistically, leptin-primed immortalized Kupffer cells (a mimicked model for an NAFLD condition) treated with apocynin or nitrone spin trap 5,5 dimethyl-1- pyrroline N-oxide (DMPO) had significantly decreased CD68 and decreased miR21 and α-smooth muscle actin levels, suggesting the role of NOX2-dependent reactive oxygen species in miR21-induced Kupffer cell activation and stellate cell pathology. Furthermore, NOX2-dependent peroxynitrite generation was primarily responsible for cellular events observed following MC exposure since incubation with phenylboronic acid attenuated miR21 levels, Kupffer cell activation, and inflammatory cytokine release. Furthermore, blocking of the AKT pathway attenuated PP2A inhibitor-induced NOX2 activation and miR21 upregulation. Taken together, we show that PP2A may have protective roles, and its inhibition exacerbates NAFLD pathology via activating NOX2-dependent peroxynitrite generation, thus increasing miR21-induced pathology.NEW & NOTEWORTHY Protein phosphatase 2A inhibition causes nonalcoholic steatohepatitis (NASH) progression via NADPH oxidase 2. In addition to a novel emchanism of action, we describe a new tool to describe NASH histopathology.

Human relaxin-2 attenuates hepatic steatosis and fibrosis in mice with non-alcoholic fatty liver disease

Human relaxin-2 reduces hepatic fibrosis in mice. However, the effects of relaxin-2 on hepatic steatosis and fibrosis in animals with non-alcoholic fatty liver disease (NAFLD) remain to be elucidated. C57BL/6 mice fed a high-fat diet (HFD) or methionine–choline-deficient (MCD) diet were randomly assigned to receive recombinant human relaxin-2 (25 or 75 μg/kg/day) or vehicle for 4 weeks. In HFD-fed mice, relaxin-2 decreased systemic insulin resistance and reduced body weight, epididymal fat mass and serum leptin and insulin concentrations. In livers of HFD-fed mice, relaxin-2 attenuated steatosis and increased phosphorylation of insulin receptor substrate-1, Akt and endothelial nitric oxide synthase (eNOS), and activated genes that regulate fatty acid oxidation and suppressed acetyl-CoA carboxylase. Relaxin-2 had no direct anti-steatotic effect on primary mouse hepatocytes, but S-nitroso-N-acetylpenicillamine attenuated palmitic acid-induced steatosis and activated genes regulating fatty acid oxidation in hepatocytes. In mice fed an MCD diet, relaxin-2 attenuated steatosis, inflammation and fibrosis. Relaxin-2 increased eNOS and Akt phosphorylation and transcript levels of cytochrome P450-4a10 and decreased acetyl-CoA carboxylase in MCD-fed mouse livers. Moreover, expression levels of Kupffer cell activation, hepatic stellate cell activation and hepatocyte apoptosis were decreased in MCD diet-fed mice receiving relaxin-2. In conclusion, relaxin-2 reduces hepatic steatosis by activating intrahepatic eNOS in HFD-fed mice and further attenuates liver fibrosis in MCD diet-fed mice. Therefore, human relaxin-2 is a potential therapeutic treatment for NAFLD.

The role of the gut microbiome in chronic liver disease: the clinical evidence revised.

SummaryRecent research has suggested a role for the intestinal microbiota in the pathogenesis and potential treatment of a wide range of liver diseases. The intestinal microbiota and bacterial products may contribute to the development of liver diseases through multiple mechanisms including increased intestinal permeability, chronic systemic inflammation, production of short-chain fatty acids and changes in metabolism. This suggests a potential role for pre-, pro- and synbiotic products in the prevention or treatment of some liver diseases. In addition, there is emerging evidence on the effects of faecal microbial transplant. Herein, we discuss the relationship between the intestinal microbiota and liver diseases, as well as reviewing intestinal microbiota-based treatment options that are currently being investigated.

Studies on the Effects of Carbonated Soft Drink Additives and Simultaneous Consumption of Carbonated Soft Drink with Ascorbic Acid on Histological Parameters of Male Mice

Sodium benzoate and ascorbic acid are the most significant additives in carbonated soft drink. The effect of consuming these additives singly and simultaneous consumption of carbonated soft drink with ascorbic acid were investigated to understand histopathological alterations in both liver cells and testis. Expermental mice were grouped into 7 different sets and five of the groups were adminstered 4 mg/kg body weight of the treatments, while the other two groups served as normal and vehicle control. The histological results reveal presence of activated Kupffer cells, sinusoidal widening and cytoplasmic vacuolation in the liver of mice exposed to carbonated soft drink, sodium benzoate and sodium benzoate with ascorbic acid, while in addition to these, there were severe cellular and granular casts in group administered carbonated soft drink with ascorbic acid. Severe cellular casts and granular cast is an indication of hepatic diseases. Carbonated soft drink, sodium benzoate, ascorbic acid and sodium benzoate with ascorbic acid did not alter the histopathology of the testis, but simultaneous consumption of carbonated soft drink with ascorbic acid might prevent the formation of new stem cells and may hinder them from dividing to specialized cells.

Role of NLRP3 inflammasome in the pathogenesis of alcoholic liver disease

Chronic excess alcohol intake triggers the formation of enterogenic endotoxemia. TLR4 ligand localization activates nuclear transcription factor NF-κB by inducing the up-regulation of NLRP3 inflammasome and the biologically inactive IL-1β and IL-18 precursors to form initiation of pro-inflammatory signals. Under the influence of ethanol, the damaged hepatocyte release uric acid, and adenosine triphosphate and induces NLRP3 inflammasome assembly and functional activation in Kupffer cells to promote the release of inflammatory mediators, such as interleukin-1β and interleukin-18, that cascade mediates inflammation and drive alcoholic liver disease from steatosis to inflammation and fibrosis. The NLRP3 inflammasome acts as a ligand-sensing element and plays an important role in mediating the immune and inflammatory response in the course of alcoholic liver disease. Thus, exploring the activation mechanism of NLRP3 inflammasome and its pathogenic role may provide a new idea in the clinical treatment of alcoholic liver disease.

1865-P: Dual Chemokine Receptor CCR2/CCR5 Antagonist Cenicriviroc Ameliorates Lipotoxicity-Induced Insulin Resistance and NASH in Mice

Hepatic lipid accumulation drives innate immunity with recruitment of bone marrow-derived macrophages and activation of liver-resident Kupffer cells, leading to insulin resistance and nonalcoholic steatohepatitis (NASH) development. However, treatment options that target macrophage/Kupffer cells recruitment or activation to halt the insulin resistance and NASH remain limited. A C-C chemokine receptor 2 (CCR2) plays a central role in macrophage recruitment. In addition, we reported that a different C-C chemokine receptor, CCR5, promotes insulin resistance and hepatic steatosis by regulating macrophage M1/M2 status. Here, we investigated the effect of cenicriviroc (CVC), a dual CCR2 and CCR5 receptor antagonist in a lipotoxic model of NASH with hepatic fibrosis and insulin resistance. Eight-week-old C57BL/6 mice were fed a high-cholesterol, high-fat (CL) diet or a CL diet containing 0.015% CVC (CL+CVC) for 12 weeks. The liver histology, insulin sensitivity, and fibrogenesis were examined. The CVC administration decreased the increase in plasma ALT levels as well as liver triglyceride, cholesterol, and TBARS levels caused by the CL diet. In addition, CVC improved glucose intolerance and hyperinsulinemia in the CL group and augmented the insulin signal, assessed by IRβ and Akt phosphorylation in the liver. Flow cytometry analysis revealed that mice fed CL+CVC had 72% fewer CD11c+CD206- M1-like macrophages, but 94% more CD11c-CD206+M2-like macrophages than CL group, indicating that CVC caused an M2-dominant shift in macrophages/Kupffer cells in the liver. Furthermore, CVC attenuated hepatic fibrosis by repressing the activation of hepatic stellate cells (HSCs) and decreasing hydroxyproline content. Thus, CVC ameliorated lipotoxicity-induced insulin resistance and NASH with hepatic fibrosis by polarizing M2 macrophage and attenuating HSC activation. Disclosure T. Ota: None. G. Chen: None. M. Nagashimada: None. Funding Japan Ministry of Education, Culture, Sports, Science and Technology

Impact of renal ischemia/reperfusion injury on the rat Kupffer cell as a remote cell: A biochemical, histological, immunohistochemical, and electron microscopic study

Almost all transplanted solid organs are exposed to some degree of ischemia-reperfusion (IR) damage. It is interesting to know that this IR damage affects various remote tissues including the liver and resulted in serious adverse effects. Liver injury triggers different responses of liver tissue especially Kupffer cells (KCs). The goal of this current study is to assess the biochemical and morphological changes of hepatic KCs after the induction of renal ischemia-reperfusion (RIR) and point out their role in remote liver injury after RIR.Sixteen male Sprague-Dawley rats were randomly divided into two equal groups: Group I; sham group. Group II; renal ischemia reperfusion (IR) group in which rats were exposed to renal ischemia for 45 min followed by renal reperfusion for 48 h. Three rats from each group were subjected to charcoal injection to evaluate KCs activity. Specimens of rat liver from each group were obtained and processed for biochemical, light microscopic and ultramicroscopic examination. The current results showed elevated serum levels of AST and ALT. The liver HGF-α protein expression increased in IR group compared to the sham group. In IR group, numerous charcoal labeled KCs were observed mainly localized around the central vein. Scanning electron micrographs showed complex primary and secondary foot process of the KCs. Ultrastructural study showed KCs with multiple cytoplasmic vacuoles, lysosomes and mitochondria, rough endoplasmic reticulum and ribosomes. Immuno-histochemical study showed more tumor necrosis factor-α (TNF-α) expression in KCs than the sham group. These results collectively demonstrated that renal IR produced biochemical and morphological changes in the liver KCs and theses cells might have a role in the remote liver injury after renal IR. This might be one of the mechanisms through which RIR affects the liver.

Frontline Science: Concanavalin A-induced acute hepatitis is attenuated in vitamin D receptor knockout mice with decreased immune cell function.

The vitamin D receptor (VDR) is a nuclear receptor for the active form of vitamin D, 1α,25-dihydroxyvitamin D3 , and regulates various physiologic processes, such as bone and calcium metabolism, cellular proliferation and differentiation, and immunity. VDR is highly expressed in the intestine, kidney, bone, and macrophages, but is expressed at a low level in the liver. The liver is a major metabolic organ and also acts as an immune gateway for dietary nutrients and xenobiotics. In this study, we investigated the function of VDR in hepatic immune cells, such as Kupffer cells/macrophages, utilizing VDR knockout (KO) mice. We showed that VDR is functionally expressed in hepatic mononuclear cells, specifically resident Kupffer cells. We examined the role of VDR in acute hepatitis induced by concanavalin A (Con-A) and found that Con-A-induced hepatitis is attenuated in VDR-KO mice compared to wild-type (WT) mice. Con-A-induced hepatitis is known to be mediated by NKT cell activation, cytokine production, and reactive oxygen species (ROS) production in Kupffer cells/macrophages. However, the proportions of Kupffer cells/macrophages and the NKT cell activation were similar in the liver of WT and VDR-KO mice and inflammatory cytokine gene expression was increased in VDR-KO mice. On the other hand, plasma and hepatic ROS levels were decreased in the liver of VDR-KO mice compared to WT mice. The phagocytic activity of resident Kupffer cells and hepatic neutrophils were also decreased in VDR-KO mice. Therefore, VDR is necessary for Con-A-induced acute hepatitis and plays an important role in hepatic immune cell functions.

The positive effect of metformin and metronidazole on the diabetic rats experimentally

Diabetes mellitus is considering most serious disease of endocrine, it affecting large number of people in worldwide. This study was performed to insured the effect of combination of metformin and metronidazole on disorder in metabolic that concomitant with injection of alloxan IP induced diabetes in rats. In this study forty male rats: divided into four groups including control group G1, alloxn group (150 mg/kg single dose) G2, alloxn group orally treated with metformin (150mg/kg/BW) G3, and alloxn group orally treated with metformin (150mg/kg/BW) and metronidazole (500mg/kg/BW) G4. The experiment last for 14 days. The result shows marked increase in MDA, glucose and also in liver enzymes, lipid profiles and even observed disorder in kidney function test by increased in the creatinine, urea, and uric acid levels. In addition to study the histological changes in diabetic liver of rats characterized by kupffer cells activation, dilation and congestion of central vein and hepatic sinusoids. Administration of metformin and combination of metformin and metronidazole, result in significant reduction return abnormal parameters to the normal values. Also correct the abnormal histological changes of liver.

The Edible Insect Gryllus bimaculatus Protects against Gut-Derived Inflammatory Responses and Liver Damage in Mice after Acute Alcohol Exposure.

Accumulation of reactive oxygen species (ROS) in response to excess alcohol exposure is a major cause of gut barrier disruption and lipopolysaccharide (LPS)-induced hepatic inflammation, as well as liver steatosis and apoptosis. This study was designed to investigate protective effects of the cricket Gryllus bimaculatus, an edible insect recognized by the Korea Food and Drug Administration, against acute alcoholic liver damage in mice. Administration of G. bimaculatus extracts (GBE) attenuated alcohol-induced steatosis and apoptotic responses in the liver and intestinal permeability to bacterial endotoxin. These protective effects were associated with suppression of ROS-mediated oxidative stress in both the liver and small intestine. Furthermore, in vivo and in vitro studies revealed that GBE inhibits LPS-induced Kupffer cell activation and subsequent inflammatory signaling. Importantly, the protective effects of GBE were more potent than those of silymarin, a known therapeutic agent for alcoholic liver diseases.

Glycine protects partial liver grafts from Kupffer cell-dependent ischemia-reperfusion injury without negative effect on regeneration.

Donor preconditioning with glycine prevents Kupffer cell-dependent reperfusion injury to liver grafts. Partial liver grafts need to regenerate and grow in size after transplantation; however, glycine inactivates Kupffer cells, which are important for hepatic regeneration. Thus, this study was designed to evaluate the impact of donor preconditioning with glycine after partial liver transplantation (pLTx). PLTx was performed in 28 female Sprague-Dawley rats. Glycine (1.5ml, 300mM; i.v.) was given to 14 live donors before organ procurement. Liver enzymes and histology were investigated 8h after reperfusion to index liver injury and leukocyte infiltration. Hepatic microperfusion and leukocyte-endothelium interaction were assessed using the in vivo fluorescence microscopy method. Ki-67 and TNF-α were detected by immunohistochemistry for regeneration and Kupffer cell activation. Glycine significantly increased survival from 0% in controls to 40%, while both liver enzyme levels and necrosis were decreased to about 50% of controls (p < 0.05). Sinusoidal blood flow increased by 40-80%, while leukocyte-endothelium interaction decreased to 30% of control values (p < 0.05). While Kupffer cell-derived TNF-α decreased to 70% of controls, there was no difference between groups in Ki-67 expression. Data presented here clearly demonstrate that glycine protects partial liver grafts from reperfusion injury without effects on regeneration.

Catestatin Improves Insulin Sensitivity by Promoting M1‐M2 Polarization and Inhibiting Obesity‐Induced Macrophage Infiltration and Gluconeogenesis in Liver

ObjectiveComponents of the innate and adaptive immune system are affected in obesity and Type 2 diabetes (T2D) and inflammation participates in the pathogenesis of T2D. The activation of the resident Kupffer cells and monocyte (Mc)‐derived recruited macrophages (McMΦs) in the liver contributes to obesity‐induced insulin resistance (IR) and T2D. Here, we sought to determine whether the Chromogranin A (CgA) peptide Catestatin (CST: human CgA352–372) regulates recruitment of macrophages and modulates metabolism in insulin‐resistant diet‐induced obese (DIO) mice as well as M1–M2 polarization in human monocytes.Methods and ResultsCST treatment of DIO mice diminished the expression of gluconeogenic genes, attenuated expression of pro‐inflammatory genes, increased expression of anti‐inflammatory genes in McMΦs, and inhibited infiltration of McMΦs, leading to improvement of insulin sensitivity. To gain better insights into the mechanism of action of CST, we isolated CD14+ subsets of monocytes from buffy coats from healthy individuals. The monocytes were cultured with M‐CSF towards undifferentiated MΦs and subsequently polarized towards pro‐inflammatory and anti‐inflammatory phenotypes with GM‐CSF, IFN‐γ and LPS or M‐CSF and IL4, respectively. RNA sequencing of proinflammatory MΦs revealed that CST decreased expression of proinflammatory genes in proinflammatory (e.g., IL23A, FCRLA, and IL1A) as well as in anti‐inflammatory MΦs (e.g., IL11RA, SP140, NLRCS, and TRIM34). In anti‐inflammatory macrophages, CST increased expression of anti‐inflammatory genes. Consistent with gene expression, CST exposure to anti‐inflammatory MΦs enhanced IL‐10 production but not in pro‐inflammatory MΦs, whereas CST inhibited TNFα and IL‐6 production in both cultures.ConclusionWe conclude that (i) CST attenuated macrophage mediated inflammation, resulting in improved insulin sensitivity in obese mice. (ii) CST promoted M1–M2 polarization by decreasing expression of proinflammatory cytokines and increasing expression of ant‐iinflammatory cytokines.Support or Funding InformationSupported by grants from the VA (I01BX000323 to S.K.M.), and the NWO Gravitation Programme 2013 (ICI‐024.002.009 to G.v.d.B.), and a Vidi grant from the Netherlands Organization for Scientific Research (NWO‐ALW VIDI 864.14.001 to G.v.d.BG.v.d.B.).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Role of Jak3 in Kupffer‐cell mediated hepatic steatosis during obesity

BackgroundJanus kinase 3 (Jak3), a non‐receptor protein kinase, plays an essential role in hematopoietic cell‐growth and differentiation of intestinal epithelial mucosa. Previously, we have shown that loss of Jak3 exacerbates symptoms of obesity associated metabolic syndrome in a murine model of diet‐induced obesity through compromised intestinal barrier functions and induction of chronic low‐grade inflammation (CLGI). Though, recent studies suggest a strong linkage between CLGI and hepatic steatosis, the genetic regulation of intestinal dysbiosis and their role in hepatic steatosis is not known. In this report, we investigated the tissue‐specific role of Jak3 in maintaining hepatic homeostasis during obesity associated metabolic syndrome.MethodsIn order to test our hypothesis, we used a global Jak3 KO (Jak3−/−) mice model and compared its effect with either the intestinal epithelial specific Jak3 KO (Int Jak3 KO) mice or immune cell specific Jak3 KO (Imm Jak3 KO) mice in a model of diet‐induced obesity. The organs were collected at the end of the study period under aseptic conditions and analyzed using a combination of flowcytometric, confocal microscopy, and western analysis techniques.ResultsOur results show increased susceptibility to obesity associated metabolic syndrome in high‐fat diet treated Jak3−/− mice compared to their co‐housed littermates. Jak3−/− mice showed increased predisposition to CLGI, hepatic steatosis, increased liver to body weight ratio, and hyperglycemia compared to their co‐housed littermate controls. To determine the tissue specific role of Jak3, a high‐degree of association between CLGI and hepatic inflammation in Imm Jak3 KO mice, indicated a prominent role of hematopoietic Jak3 in maintaining Kupffer‐cell mediated hepatic steatosis. A differential flowcytometric assay showed an increased influx of monocytes, but reduced differentiation of residential Kupffer cells in imm Jak3 KO mice compared to its floxed control during diet‐induced obesity. Further, the same group of mice also showed an increased hepatic expression of TLR‐2 and TLR‐4 and a higher IL‐6, IL‐17 and Tnf‐α as compared to the control mice. Together, these results showed that a lack of Jak3 expression in immune cells leads to CLGI and a compromise in the activation of Kupffer cells coupled with increased extravasation of the circulating monocytes into the liver. This could lead to hepatic steatosis in obesity. In addition, we also found an increased Th17 effector function and simultaneous suppression of Treg cell proliferation in the absence of immune cell Jak3, when compared to its control mice, on treatment with HFD.ConclusionCollectively, these results indicate that Jak3 plays a major role in regulating the macrophage based hepatic homeostasis.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.