Hepatic IR Research Articles

366.7: NAFLD aggravates hepatic IR injury by inhibiting hepatocyte Nrf2 and activating macrophage STING signaling.

366.7: NAFLD aggravates hepatic IR injury by inhibiting hepatocyte Nrf2 and activating macrophage STING signaling.

Protective Effects of Stem Cells and Vitamin D3 Against Hepatic Ischemia/Reperfusion Injury in Rats

Abstract Background Liver transplantation is one of the most efficient life-saving treatments for various end-stage hepatic diseases. However, hepatic ischemic reperfusion injury (IRI) remains a major problem in liver surgeries morbidities and mortalities. Stem cells (SCs) have been recently received increasing attention for cell-based therapy, especially in regenerative medicine, including liver diseases. Aim to investigate the effect of vitamin D and Bone Marrow Mesenchymal Stem Cells (BM- MSCs) solely or combined on hepatic IR injury. Methods Sixty adult male Wister rats were allocated into 5 groups; Sham, IR: underwent hepatic IR, vit. D-IR: received vit. D in a dose of 500 IU/Kg/day, by gavage, 5 days/week for 2 weeks, then subjected to hepatic IR, Stem cell-IR: received single IV injection of 1 × 106 BM-MSCs prior to hepatic IR and Combined-IR: received both vit. D and BM-MSCs prior to hepatic IR. All rats were subjected to estimation of Liver index (LI), assessment of serum levels of alanine, aspartate transaminases (ALT, AST) and vitamin D, hepatic tissue levels of Malondialdehyde (H.MDA), Superoxide dismutase (H.SOD), Interleukin-2, 10 (H.IL-2, H.IL-10), Caspase-3 (H.Casp-3), H.LC3B and hepatocyte growth factor (H.HGF), as well as histopathological liver examination and scoring. Results Hepatic IR resulted in significant elevation of ALT, AST and H.MDA, H.IL-2, H. Casp- 3 as well as significant reduction in LI, vit. D, H.SOD, H.IL-10, H.LC3B and H.HGF with evident hepatic sinusoidal congestion, cytoplasmic vacuolation and cellular necrosis. Treatment either solely or in combination mitigate these changes with the combined treatment showed the best results compared to the individual use. Conclusion In vivo coadministration of vitamin D and BM-MSCs prior to hepatic IR attenuated hepatocellular damage through preventing oxidative stress and inflammatory response, augmenting autophagic, regenerative capacity and anti-apoptotic effect.

Adipose Tissue Insulin Resistance Correlates with Disease Severity in Pediatric Metabolic Dysfunction-Associated Steatotic Liver Disease: A Prospective Cohort Study

ObjectivesTo assess the role of adipose tissue insulin resistance (Adipo-IR) in the pathogenesis of pediatric metabolic dysfunction-associated steatotic liver disease (MASLD) and to determine Adipo-IR evolution during a lifestyle intervention program. Study designIn this prospective, cohort study, children and adolescents with severe obesity were recruited between July 2020 and December 2022 at an inpatient pediatric rehabilitation center. Treatment consisted of dietary intervention and physical activity. Liver steatosis and fibrosis were evaluated using ultrasound and transient elastography with controlled attenuation parameter and liver stiffness measurement. Every 4 to 6 months, anthropometric measurements, serum biochemical analysis, ultrasound and elastography were repeated. Adipo-IR was estimated by the product of the fasting serum insulin times the fasting free fatty acid concentration and hepatic IR by the homeostatic model assessment for insulin resistance (HOMA-IR), respectively. Results56% of 200 patients with obesity had evidence of steatosis on ultrasound and 26% were diagnosed with fibrosis (≥F2). Adipo-IR increased progressively from lean controls to patients with obesity to patients with MASLD and MASLD with fibrosis. Adipo-IR was already elevated in patients with only mild steatosis (p = 0.0403). Patients with more insulin-sensitive adipose tissue exhibited lower liver fat content (p < 0.05) and serum alanine transaminase levels (p = 0.001). Adipo-IR correlated positively with visceral adipose tissue weight, waist circumference, and the visceral adipose tissue/gynoid adipose tissue ratio (p < 0.001), but not with total body fat percentage (p = 0.263). After 4 to 6 months of lifestyle management, both MASLD and Adipo-IR improved. ConclusionsOur data suggest that Adipo-IR is associated with the presence of pediatric MASLD, particularly steatosis.

Effect of Gallic Acid Treatment on Hepatic Tissue in Ischemia-Reperfusion

Aim: Hepatic IR occurs in many clinical conditions such as liver injury, liver hemorrhage and shock, surgical resection, and transplantation. In our study, it is aimed to investigate whether gallic acid (GA) can be used for hepatoprotective purposes, histopathologically.&#x0D; Study Desıgn: 24 Wistar albino male rats were divided into 3 groups (n:8). Surgical procedures were done under general anesthesia. A 4 cm midline abdominal incision were opened to observe hepatoduodenal ligament. The portal vein and hepatic artery was closed with a rubber band and silk suture, and ischemia was performed for 60 minutes. The suture was opened and hepatic reperfusion was performed for 6 hours. 50 mg/kg Gallic Acid was administered to the rats in this group by intraperitoneal route once a day for 14 days.&#x0D; Results: Normal histology of lvier was observed with regular vena centralis, endothelial cells, hepatocytes and sinusoid. In IR group, blood vessels were dilated and congested with cell infiltrations. Hepatocytes were degenerated with irregular sinusoides and hyperplasic Kupfer cells. IR+GA group, mononuclear cell infiltration continued with thickening of the basement membrane of the vessels. Vacuolated hepatocyte was observed. GA treatment alleviasted the pathologies occurred due to IR injury.&#x0D; Conclusion: It was thought that the cellular damage in the inflammation signal, which started as a result of the cessation of blood flow after ischemia-reperfusion injury, affects the classical lobule of the liver especially around the vena, and may cause necrotic changes by increasing cell apoptosis due to functional nutritional deficiency.&#x0D; Keywords: liver, ischemia, reperfusion, gallic acid, histology

P21-activated kinase 4 inhibition protects against liver ischemia/reperfusion injury: Role of nuclear factor erythroid 2-related factor 2 phosphorylation.

p21-activated kinase 4 (PAK4), an oncogenic protein, has emerged as a promising target for anticancer drug development. Its role in oxidative stress conditions, however, remains elusive. We investigated the effects of PAK4 signaling on hepatic ischemia/reperfusion (I/R) injury. Hepatocyte- and myeloid-specific Pak4 knockout (KO) mice and their littermate controls were subjected to a partial hepatic I/R (HIR) injury. We manipulated the catalytic activity of PAK4, either through genetic engineering (gene knockout, overexpression of wild-type [WT] or dominant-negative kinase) or pharmacological inhibitor, coupled with a readout of nuclear factor erythroid 2-related factor 2 (Nrf2) activity, to test the potential function of PAK4 on HIR injury. PAK4 expression was markedly up-regulated in liver during HIR injury in mice and humans. Deletion of PAK4 in hepatocytes, but not in myeloid cells, ameliorated liver damages, as demonstrated in the decrease in hepatocellular necrosis and inflammatory responses. Conversely, the forced expression of WT PAK4 aggravated the pathological changes. PAK4 directly phosphorylated Nrf2 at T369, and it led to its nuclear export and proteasomal degradation, all of which impaired antioxidant responses in hepatocytes. Nrf2 silencing in liver abolished the protective effects of PAK4 deficiency. A PAK4 inhibitor protected mice from HIR injury. PAK4 phosphorylates Nrf2 and suppresses its transcriptional activity. Genetic or pharmacological suppression of PAK4 alleviates HIR injury. Thus, PAK4 inhibition may represent a promising intervention against I/R-induced liver injury.

Single Point Insulin Sensitivity Estimator in Pediatric Non-Alcoholic Fatty Liver Disease.

BackgroundAttenuated insulin-sensitivity (IS) is a central feature of pediatric non-alcoholic fatty liver disease (NAFLD). We recently developed a new index, single point insulin sensitivity estimator (SPISE), based on triglycerides, high-density-lipoprotein and body-mass-index (BMI), and validated by euglycemic-hyperinsulinemic clamp-test (EHCT) in adolescents. This study aims to assess the performance of SPISE as an estimation of hepatic insulin (in-)sensitivity. Our results introduce SPISE as a novel and inexpensive index of hepatic insulin resistance, superior to established indices in children and adolescents with obesity.Materials and MethodsNinety-nine pubertal subjects with obesity (13.5 ± 2.0 years, 59.6% males, overall mean BMI-SDS + 2.8 ± 0.6) were stratified by MRI (magnetic resonance imaging) into a NAFLD (>5% liver-fat-content; male n=41, female n=16) and non-NAFLD (≤5%; male n=18, female n=24) group. Obesity was defined according to WHO criteria (> 2 BMI-SDS). EHCT were used to determine IS in a subgroup (n=17). Receiver-operating-characteristic (ROC)-curve was performed for diagnostic ability of SPISE, HOMA-IR (homeostatic model assessment for insulin resistance), and HIRI (hepatic insulin resistance index), assuming null hypothesis of no difference in area-under-the-curve (AUC) at 0.5.ResultsSPISE was lower in NAFLD (male: 4.8 ± 1.2, female: 4.5 ± 1.1) than in non-NAFLD group (male 6.0 ± 1.6, female 5.6 ± 1.5; P< 0.05 {95% confidence interval [CI]: male NAFLD 4.5, 5.2; male non-NAFLD 5.2, 6.8; female NAFLD 4.0, 5.1, female non-NAFLD 5.0, 6.2}). In males, ROC-AUC was 0.71 for SPISE (P=0.006, 95% CI: 0.54, 0.87), 0.68 for HOMA-IR (P=0.038, 95% CI: 0.48, 0.88), and 0.50 for HIRI (P=0.543, 95% CI: 0.27, 0.74). In females, ROC-AUC was 0.74 for SPISE (P=0.006), 0.59 for HOMA-IR (P=0.214), and 0.68 for HIRI (P=0.072). The optimal cutoff-level for SPISE between NAFLD and non-NAFLD patients was 5.18 overall (Youden-index: 0.35; sensitivity 0.68%, specificity 0.67%).ConclusionSPISE is significantly lower in juvenile patients with obesity-associated NAFLD. Our results suggest that SPISE indicates hepatic IR in pediatric NAFLD patients with sensitivity and specificity superior to established indices of hepatic IR.

N-acetylgalactosaminyltransferase-4 protects against hepatic ischemia/reperfusion injury by blocking apoptosis signal-regulating kinase 1 N-terminal dimerization.

Ischemia-reperfusion (I/R) injury is an inevitable complication of liver transplantation (LT) and compromises its prognosis. Glycosyltransferases have been recognized as promising targets for disease therapy, but their roles remain open for study in hepatic I/R (HIR) injury. Here, we aim to demonstrate the exact function and molecular mechanism of a glycosyltransferase, N-acetylgalactosaminyltransferase-4 (GALNT4), in HIR injury. By an RNA-sequencing data-based correlation analysis, we found a close correlation between GALNT4 expression and HIR-related molecular events in a murine model. mRNA and protein expression of GALNT4 were markedly up-regulated upon reperfusion surgery in both clinical samples from subjects who underwent LT and in a mouse model. We found that GALNT4 deficiency significantly exacerbated I/R-induced liver damage, inflammation, and cell death, whereas GALNT4 overexpression led to the opposite phenotypes. Our in-depth mechanistic exploration clarified that GALNT4 directly binds to apoptosis signal-regulating kinase 1 (ASK1) to inhibit its N-terminal dimerization and subsequent phosphorylation, leading to a robust inactivation of downstream c-Jun N-terminal kinase (JNK)/p38 and NF-κB signaling. Intriguingly, the inhibitory capacity of GALNT4 on ASK1 activation is independent of its glycosyltransferase activity. GALNT4 represents a promising therapeutic target for liver I/R injury and improves liver surgery prognosis by inactivating the ASK1-JNK/p38 signaling pathway.

Beta cell functionality and hepatic insulin resistance are major contributors to type 2 diabetes remission and starting pharmacological therapy: from CORDIOPREV randomized controlled trial

In order to assess whether previous hepatic IR (Hepatic-IRfasting) and beta-cell functionality could modulate type 2 diabetes remission and the need for starting glucose-lowering treatment, newly-diagnosed type 2 diabetes participants who had never received glucose-lowering treatment (190 out of 1002) from the CORonary Diet Intervention with Olive oil and cardiovascular PREVention study (a prospective, randomized and controlled clinical trial), were randomized to consume a Mediterranean or a low-fat diet. Type 2 diabetes remission was defined according to the American Diabetes Association recommendation for levels of HbA1c, fasting plasma glucose and 2h plasma glucose after oral glucose tolerance test, and having maintained them for at least 2 consecutive years. Patients were classified according to the median of Hepatic-IRfasting and beta-cell functionality, measured as the disposition index (DI) at baseline. Cox proportional hazards regression determined the potential for Hepatic-IRfasting and DI indexes as predictors of diabetes remission and the probability of starting pharmacological treatment after a 5-year follow-up. Low-Hepatic-IRfasting or high-DI patients had a higher probability of diabetes remission than high-Hepatic-IRfasting or low-DI subjects (HR:1.79; 95% CI 1.06-3.05; and HR:2.66; 95% CI 1.60-4.43, respectively) after a dietary intervention with no pharmacological treatment and no weight loss. The combination of low-Hepatic-IRfasting and high-DI presented the highest probability of remission (HR:4.63; 95% CI 2.00-10.70). Among patients maintaining diabetes, those with high- Hepatic-IRfasting and low-DI showed the highest risk of starting glucose-lowering therapy (HR:3.24;95% CI 1.50-7.02). Newly-diagnosed type 2 diabetes patients with better beta-cell functionality and lower Hepatic-IRfasting had a higher probability of type 2 diabetes remission in a dietary intervention without pharmacological treatment or weight loss, whereas among patients not achieving remission, those with worse beta-cell functionality and higher Hepatic-IRfasting index had the highest risk of starting glucose-lowering treatment after 5 years of follow-up.

Sevoflurane Postconditioning Attenuates Hepatic Ischemia-Reperfusion Injury by Limiting HMGB1/TLR4/NF-κB Pathway via Modulating microRNA-142 in vivo and in vitro.

Preconditioning of sevoflurane (Sevo) has been demonstrated to protect the liver from ischemia/reperfusion (I/R) injury. However, it is unknown whether it has hepatoprotective when given at the onset of reperfusion (postconditioning), a protocol with more clinical impact. The present study aimed to explore the hepatoprotective effects of Sevo postconditioning against hepatic IR injury in vivo and in vitro and the possible mechanisms. Using a mouse model of hepatic I/R, Sevo postconditioning significantly improved hepatic injury after reperfusion, as demonstrated by reduced AST, ALT, and LDH serum levels and reduced histologic damage in liver tissues. Furthermore, Sevo postconditioning could suppress the apoptosis, inhibit oxidative stress and inflammatory response in liver tissue of HIRI mice, as well as improve the survival rate of HIRI mice. Through analyzing GSE72314 from the gene expression omnibus (GEO) database, it was demonstrated that microRNA (miR)-142 is downregulated by HIRI, which was reversed by Sevo treatment. Further investigation showed that agomiR-142 injection could enhance the hepatoprotective effects of Sevo postconditioning on I/R injury, while antagomiR-142 reversed these effects in mice. Notably, high mobility group box 1 (HMGB1), an important inflammatory factor, was directly targeted by miR-142 in hepatic cells, and we further found that Sevo could inhibit the expression of HMGB1 through up-regulating miR-142 expression in HIRI mice model. In addition, we found that I/R injury induced the activation of TLR4/NF-κB inflammatory pathway was partially suppressed by Sevo postconditioning, and miR-142 mediated the regulatory role of Sevo postconditioning. In line with the in vivo results, Sevo treatment improved the cell viability, inhibited cell apoptosis, oxidative stress and inflammatory response in vitro HIRI model, while these effects were reversed by antagomiR-142 transfection. Collectively, our findings demonstrated that Sevo postconditioning counteracts the downregulation of miR-142 provoked by I/R, in turn decreased the expression of HMGB1, blocking TLR4/NF-κB pathway activation, thus improving hepatic I/R injury. Our data suggest that Sevo may be a valuable alternative anaesthetic agent in liver transplantation and major liver surgeries.

Pemafibrate Pretreatment Attenuates Apoptosis and Autophagy during Hepatic Ischemia-Reperfusion Injury by Modulating JAK2/STAT3β/PPARα Pathway.

Hepatic ischemia-reperfusion injury (HIRI) is a common phenomenon in liver transplantation and liver surgery. This article is aimed at clarifying the role of pemafibrate in HIRI through JAK2/STAT3β/PPARα. In the experiment, we divided Balb/c into seven groups, namely, normal control (NC), Sham, PEM (1.0 mg/kg), IRI, IRI + PEM (0.1 mg/kg), IRI + PEM (0.5 mg/kg), and IRI + PEM (1.0 mg/kg). We used biochemical assay, histopathological evaluation, immunohistochemistry, RT-PCR and qRT-PCR, ELISA analysis, and other methods to determine the level of serum AST, ALT, IL-1β, and TNF-α in the liver at three time points (2 h, 8 h, and 24 h) after reperfusion of apoptosis factor, autophagy factor, and the JAK2/STAT3/PPARα content in tissues. Our experiment results showed that the pemafibrate can effectively reduce the level of hepatic IR injury. In addition, pemafibrate has anti-inflammatory, antiapoptotic, and antiautophagy effects, which are mediated by the JAK2/STAT3β/PPARα pathway.

Protective effects of gastrodin pretreatment on mouse hepatic ischemia‑reperfusion occurring through antioxidant and anti‑apoptotic mechanisms

Hepatic ischemia-reperfusion injury (HIRI) often occurs following surgical procedures such as liver resection and transplantation. However, despite its clinical prominence, to the best of our knowledge, there remain no effective strategies to treat HIRI. Therefore, the aim of present study was to identify therapeutic agents that can exert beneficial effects against HIRI. The present study found that following hepatic IR modeling in mice, gastrodin (Gas) pretreatment improved the IR outcomes in terms of the serum biochemical indexes (alanine transaminase and aspartate transaminase), tissue biochemical indexes (superoxide dismutase, malondialdehyde and reduced glutathione content) and tissue pathology (H&E staining). In addition, compared with those in the IR + vehicle group, the IR + Gas group showed upregulated expression levels of nuclear erythroid 2-related factor 2, heme oxygenase 1 and Bcl-2 as detected by western blotting and reverse transcription-quantitative PCR. The mRNA and protein expression levels of Bax and caspase-3 were downregulated in the IR + Gas group compared with the IR + vehicle group. Concurrently, no significant differences were observed in the parameters between the Sham + vehicle and the Sham + Gas groups, indicating that Gas pretreatment may not cause liver damage. In conclusion, the findings of the present study revealed that Gas pretreatment exerted a protective effect in HIRI through both antioxidant and anti-apoptotic mechanisms.

Fenofibrate Ameliorates Hepatic Ischemia/Reperfusion Injury in Mice: Involvements of Apoptosis, Autophagy, and PPAR-α Activation.

Hepatic ischemia and reperfusion injury is characterized by hepatocyte apoptosis, impaired autophagy, and oxidative stress. Fenofibrate, a commonly used antilipidemic drug, has been verified to exert hepatic protective effects in other cells and animal models. The purpose of this study was to identify the function of fenofibrate on mouse hepatic IR injury and discuss the possible mechanisms. A segmental (70%) hepatic warm ischemia model was established in Balb/c mice. Serum and liver tissue samples were collected for detecting pathological changes at 2, 8, and 24 h after reperfusion, while fenofibrate (50 mg/kg, 100 mg/kg) was injected intraperitoneally 1 hour prior to surgery. Compared to the IR group, pretreatment of FF could reduce the inflammatory response and inhibit apoptosis and autophagy. Furthermore, fenofibrate can activate PPAR-α, which is associated with the phosphorylation of AMPK.

Lipoprotein Insulin Resistance Index Reflects Liver Fat Content in Patients With Nonalcoholic Fatty Liver Disease.

The recently developed lipoprotein insulin resistance index (LP‐IR) incorporates lipoprotein particle numbers and sizes and is considered to reflect both hepatic and peripheral IR. As tissue IR is a strong component of nonalcoholic fatty liver disease (NAFLD) pathogenesis, we aimed to assess the degree by which LP‐IR associates with hepatic fat content. This was a single‐center retrospective analysis of patients with NAFLD. LP‐IR, the homeostasis model assessment of insulin resistance (HOMA‐IR), and adipose tissue IR (Adipo‐IR) were measured simultaneously. Liver fat content was estimated by FibroScan controlled attenuated parameter. Associations were assessed using Spearman’s correlation and multivariate linear regression. The study included 61 patients. LP‐IR was correlated with HOMA‐IR (ρ = 0.30; P = 0.02), typically thought to reflect hepatic IR, but not with Adipo‐IR (ρ = 0.15; P = 0.25). Liver fat content was significantly associated with Adipo‐IR (ρ = 0.48; P < 0.001), LP‐IR (ρ = 0.35; P = 0.005), and to a lesser degree with HOMA‐IR (ρ = 0.25; P = 0.051). The association of liver fat with LP‐IR was limited to patients without diabetes (ρ = 0.60; P < 0.0001), whereas no association was seen in those with diabetes. In a multivariate model, Adipo‐IR, LP‐IR, and diabetes were independently associated with liver fat and together explained 35% of the variability in liver fat. Conclusion: LP‐IR is a reasonable measure of IR in non‐diabetic patients with NAFLD and is associated with hepatic fat content. Although adipose tissue is the major contributor to liver fat, the additional contribution of nonadipose tissues can be easily estimated using LP‐IR.

β-Arrestin-2 attenuates hepatic ischemia-reperfusion injury by activating PI3K/Akt signaling.

Hepatic ischemia-reperfusion injury (IRI) remains a common complication during liver transplantation (LT), partial hepatectomy and hemorrhagic shock in patients. As a member of the G protein-coupled receptors adaptors, ARRB2 has been reported to be involved in a variety of physiological and pathological processes. However, whether β-arrestin-2 affects the pathogenesis of hepatic IRI remains unknown. The goal of the present study was to determine whether ARRB2 protects against hepatic IR injury and elucidate the underlying mechanisms. To this end, 70% hepatic IR models were established in ARRB2 knockdown mice and wild-type littermates, with blood and liver samples collected at 1, 6 and 12 h after reperfusion to evaluate liver injury. The effect of ARBB2 on PI3K/Akt signaling during IR injury was evaluated in vivo, and PI3K/Akt pathway regulation by ARRB2 was further assessed in vitro. Our results showed that ARRB2 knockdown aggravates hepatic IR injury by promoting the apoptosis of hepatocytes and inhibiting their proliferation. In addition, ARRB2 deficiency inhibited PI3K/Akt pathway activation, while the administration of the PI3K/Akt inhibitor PX866 resulted in severe IR injury in mice. Furthermore, the liver-protecting effect of ARRB2 was shown to depend on PI3K/Akt pathway activation. In summary, our results suggest that β-Arrestin-2 protects against hepatic IRI by activating PI3K/Akt signaling, which may provide a novel therapeutic strategy for treating liver ischemia-reperfusion injury.

P1 Efectos del tratamiento con N-acetil-cisteína en ratas tratadas con una dieta rica en fructosa: ¿reversión o prevención?

Introducción: la sobrecarga de fructosa promueve estrés oxidativo (EO) que induce daño metabólico, IR hepática y respuesta inflamatoria local, alteraciones similares a las observadas en el SM humano. La NAC (N-acetil-cisteína) posee capacidad antioxidante, provee sustratos para la síntesis de GSH y presenta una elevada absorción a nivel hepático.Objetivos: estudiar los efectos de la administración de NAC por vía oral e i.p. a distintas dosis, sobre las alteraciones endócrino-metabólicas inducidas por la dieta rica en fructosa.Materiales y métodos: se utilizaron ratas SpragueDawley macho de 60 días de vida que se dividieron en 6 grupos y se alimentaron 21 días ad libitum. El grupo control recibió dieta comercial estándar y agua corriente; el grupo fructosa (F) tuvo acceso a dieta comercial estándar con el agregado de fructosa al 10% en el agua de bebida. Para el tratamiento con NAC se administró en la bebida junto con la fructosa asegurando una dosis diaria de 25 mg/día (FN25), también se ensayaron 1 g/l y 2 g/l (FN1 y FN2) por 21 días y vía i.p. 50 mg/kg en solución fisiológica los últimos 5 días de tratamiento (FN50). Culminado el tratamiento, se sacrificaron los animales y se determinaron en suero: glucemia, trigliceridemia, colesterol total y HDL, AST, ALT, ácido úrico y TBARS séricos y se calcularon los índices glucemia-trigliceridemia (Glu-TG), trigliceridemia/HDL (TG/HDL) y AST/ALT. A nivel hepático se determinó la actividad de las enzimas glucoquinasa (GQ) y fructoquinasa (FQ) así como contenido de glucógeno.

Human Antigen R (HuR): A Regulator of Heme Oxygenase-1 Cytoprotection in Mouse and Human Liver Transplant Injury.

Background and AimsIschemia–reperfusion injury (IRI) represents a risk factor in liver transplantation (LT). We have shown that overexpression of heme oxygenase‐1 (HO‐1) mitigates hepatic IRI in LT recipients. Here, we hypothesized that human antigen R (HuR), the stabilizer of adenylate‐uridylate (AU)‐rich mRNAs, is required for hepatoprotection in LT.Approach and ResultsIn an experimental arm, HuR/HO‐1 protein expression was correlated with hepatic IRI phenotype. In an in vitro inflammation mimic model of hepatic warm IRI, induction of HuR/HO‐1 and cytoplasmic localization following cytokine preconditioning were detected in primary hepatocyte cultures, whereas HuR silencing caused negative regulation of HO‐1, followed by enhanced cytotoxicity. Using the HuR‐inhibitor, we showed that HuR likely regulates HO‐1 through its 3′ untranslated region and causes neutrophil activation (CD69+/lymphocyte antigen 6 complex locus G [Ly6‐G]). HuR silencing in bone marrow–derived macrophages decreased HO‐1 expression, leading to the induction of proinflammatory cytokines/chemokines. RNA sequencing of HuR silenced transcripts under in vitro warm IRI revealed regulation of genes thymus cell antigen 1 (THY1), aconitate decarboxylase 1 (ACOD1), and Prostaglandin E Synthase (PTGES). HuR, but not hypoxia‐inducible protein alpha, positively regulated HO‐1 in warm, but not cold, hypoxia/reoxygenation conditions. HuR modulated HO‐1 in primary hepatocytes, neutrophils, and macrophages under reperfusion. Adjunctive inhibition of HuR diminished microtubule‐associated proteins 1A/1B light chain 3B (LC3B), a marker for autophagosome, under HO‐1 regulation, suggesting a cytoprotective mechanism in hepatic IR. In a clinical arm, hepatic biopsies from 51 patients with LT were analyzed at 2 hours after reperfusion. Graft HuR expression was negatively correlated with macrophage (CD80/CD86) and neutrophil (Cathepsin G) markers. Hepatic IRI increased HuR/HO‐1 expression and inflammatory genes. High HuR–expressing liver grafts showed lower serum alanine aminotransferase/serum aspartate aminotransferase levels and improved LT survival.ConclusionsThis translational study identifies HuR as a regulator of HO‐1–mediated cytoprotection in sterile liver inflammation and a biomarker of ischemic stress resistance in LT.

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.

1746-P: Obese Youth with Type 1 Diabetes (T1D) Have Worse Hepatic Insulin Resistance (IR) Than Youth with Type 2 Diabetes (T2D)

Background: The epidemic of obesity is growing in the U.S. due to changes in diet and lifestyle. Similar trends are also now occurring in T1D youth and may worsen IR and associated cardiovascular risk. However, the impact of obesity on IR in each tissue is unknown in T1D. Thus, we evaluated adipose, hepatic and muscle IR in obese youth with T1D, compared to BMI-similar control or T2D youth. Methods: 20 youth with T1D (age 16.0±2.3 years; % female 55; BMI%ile 95th [97, 98]; HbA1c 8.7±1.6%), 20 youth with T2D (age 15.4±2.3; % female 52; BMI%ile 95th [98, 99]; HbA1c 8.5±2.4%) and 16 controls (age 14.8±1.8; % female 55; BMI%ile 97th [98, 99]) were included. In those with diabetes, glucose was controlled overnight by IV insulin to a target of ∼100 mg/dL. A 4-phase hyperinsulinemic-euglycemic clamp (basal, 10, 16 and 80 mU/m2/min of insulin [I]) with isotopic tracers was performed the following AM to assess adipose, hepatic and muscle IR, respectively. Free fatty acids (FFA), glucose rate of disappearance (Rd) and glycerol and glucose rate of appearance (Ra) and %suppression (basal to 80 phase) were calculated. Results: Participant age, sex, BMI and Tanner stage were similar between groups. HbA1c was similar in groups with diabetes. During the basal phase, glycerol Ra/I and glucose Ra/I were similar between groups, but FFA/I was highest in obese controls (p&amp;lt;0.001). At phase 10, glycerol Ra/I was similar between groups but FFA/I at phase 10 and 16 were similarly higher in T1D and T2D vs. controls (p=0.004, p&amp;lt;0.001). At phase 16, glucose Ra/I and glycerol Ra/I were highest in T1D (p&amp;lt;0.001, p&amp;lt;0.001). At phase 80, T1D vs. T2D had similarly lower %glycerol Ra suppression than controls (p&amp;lt;0.001) but higher glycerol Ra/I and glucose Rd in T1D vs. T2D (p=0.003, p=0.042). T1D youth and controls had similar glucose Rd (p=0.25). Conclusion: Obese youth with T1D have similar to worse adipose, worse hepatic, and less muscle IR than those with T2D. Treatment targeting obesity and IR is critically needed in T1D youth. Disclosure P. Wiromrat: None. M. Cree-Green: Advisory Panel; Self; Novo Nordisk Inc. B.C. Bergman: Consultant; Spouse/Partner; Novo Nordisk Inc., Sanofi US. Research Support; Self; Eli Lilly and Company. Speaker’s Bureau; Spouse/Partner; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc., Merck &amp; Co., Inc. K.L. Tommerdahl: None. A. Baumgartner: None. L. Pyle: None. K.J. Nadeau: None. Funding American Diabetes Association (7-11-CD-08 to K.J.N.); National Heart, Lung, and Blood Institute; National Institute of Diabetes and Digestive and Kidney Diseases; JDRF

Hepatoprotective properties of p-coumaric acid in a rat model of ischemia-reperfusion.

The liver as a highly metabolic organ, has a crucial role in human body. Its function is often impressed by changes of the blood flow, hypovolemic shock, transplantation, etc. Maintaining liver function is a major challenge and there are many approaches to potentiate this organ against different stresses. Antioxidants protect organs against oxidative stress. P-coumaric acid (PC) as an oxidant has many beneficial effects. Therefore, PC was used as a pretreatment to test its potential against oxidative stress induced by liver Ischemia-reperfusion injury in rats. In order to test the potential hepatoprotective effect of PC against IR injury, five groups of rats were used: Normal (NC; intact group); Sham; p-coumaric acid (PC); IR-CO, and PC-IR. PC, Sham, NC, PC-IR and IR-CO groups that received vehicle or p-coumaric acid at a dose of 100 mg/kg for 7 consecutive days as pretreatment before IR induction. Animals in PC-IR, and IR-CO groups underwent hepatic IR injury. Liver levels of antioxidants were determined and functional liver tests were done. Hematoxylin and eosin staining was done to determine the structural changes of the liver. Gene expression of caspase-3 was also assessed. Hepatic IR injury disrupted liver function by increasing the levels of AST, and ALT, and decreasing GSH, SOD and catalase. PC significantly decreased liver inflammation, reverted liver functional enzymes and antioxidants levels to normal, reduced the gene expression of caspase-3 in PC-IR rats compared to the IR-CO group. These findings revealed that PC through improving liver´s antioxidants, liver functional tests and down-regulating apoptotic gene protein, caspase-3, protects the liver against injury induced by IR.

Association of non-alcoholic fatty liver disease (NAFLD) and insulin resistance in type 2diabetes

Background Non-alcoholic fatty liver disease NAFLD is one of the leading causes of nonalcoholic steatohepatitis NASH cirrhosis and hepatocellular carcinoma and is a major risk factor in hepatic insulin resistance IR. IR appears to be a common pathophysiological link between NAFLD and type 2 diabetes mellitus T2DM and limited information is available on the association of NAFLD with IR in T2DM individuals. We decided to determine whether there is association of NAFLD with IR in T2DM subjects.Material amp Methods Study involving 151 53 males 98 females T2DM subjects were screened for NAFLD using abdominal ultrasound scanning clinical assessment and biochemical parameters. IR was calculated using HOMA-IR. Association between NAFLD and IR was tested by Chi-square analysis. Significant difference between NAFLD and non-NAFLD subgroups was analyzed by t-test and z-test.Results The prevalence of NAFLD IR and hypertension in T2DM subjects were found to be 73 81 and 80 respectively. There was no significant difference in the prevalence of these between male amp female. However the prevalence of obesity and central obesity was significantly high in females. The comparison between NAFLD and non-NAFLD subgroups showed significantly high prevalence of IR hypertension obesity central obesity elevated SGPT and TG in NAFLD group. However there was no significant difference in mean values of serum biochemical parameters except TG VLDL and SGPT. NAFLD showed strong association with IR OR 13.ConclusionThe study indicated high prevalence of NAFLD and IR and strong association between them in diabetic population.