Histone deacetylase 6 deficiency protects the liver against ischemia/reperfusion injury by activating PI3K/AKT/mTOR signaling.

Liver transplantation (LT) is the only effective method to treat end-stage liver disease. Hepatic ischemia-reperfusion injury (IRI) continues to limit the prognosis of patients receiving LT. Histone deacetylase 6 (HDAC6) is a unique HDAC member involved in inflammation and apoptosis. However, its role and mechanism in hepatic IRI have not yet been reported. We examined HDAC6 levels in liver tissue from LT patients, mice challenged with liver IRI, and hepatocytes subjected to hypoxia/reoxygenation (H/R). In addition, HDAC6 global-knockout (HDAC6-KO) mice, adeno-associated virus-mediated liver-specific HDAC6 overexpressing (HDAC6-LTG) mice, and their corresponding controls were used to construct hepatic IRI models. Hepatic histology, inflammatory responses, and apoptosis were detected to assess liver injury. The molecular mechanisms of HDAC6 in hepatic IRI were explored in vivo and in vitro. Moreover, the HDAC6-selective inhibitor tubastatin A was used to detect the therapeutic effect of HDAC6 on liver IRI. Together, our results showed that HDAC6 expression was significantly upregulated in liver tissue from LT patients, mice subjected to hepatic I/R surgery, and hepatocytes challenged by hypoxia/reoxygenation (H/R) treatment. Compared with control mice, HDAC6 deficiency mitigated liver IRI by inhibiting inflammatory responses and apoptosis, whereas HDAC6-LTG mice displayed the opposite phenotype. Further molecular experiments show that HDAC6 bound to and deacetylated AKT and HDAC6 deficiency improved liver IRI by activating PI3K/AKT/mTOR signaling. In conclusion, HDAC6 is a key mediator of hepatic IRI that functions to promote inflammation and apoptosis via PI3K/AKT/mTOR signaling. Targeting hepatic HDAC6 inhibition may be a promising approach to attenuate liver IRI.

Sirtuin4 alleviates severe acute pancreatitis by regulating HIF-1α/HO-1 mediated ferroptosis.

Acute pancreatitis (AP) is a common emergency of the digestive system and serious cases can develop into severe acute pancreatitis (SAP), which ortality rates up to 30%. Sirtuin4 (SIRT4) is a member of the sirtuin family, and plays a key role in inflammation and oxidative stress. However, the potential role of SIRT4 in SAP has yet to be elucidated. In the present study, we found that the expression level of SIRT4 in human AP was downregulated by screening a public database, suggesting that SIRT4 may play a role in AP. Subsequently, we used L-arginine (L-Arg) to induce SAP in SIRT4 knockout (SIRT4_KO) and SIRT4 overexpression (AAV_SIRT4) mice. The results showed that the pancreatic tissue injury and related lung and kidney injury were serious in SIRT4_KO mice after SAP induction, but were significantly reduced in AAV_SIRT4 mice. More importantly, we found that the levels of antioxidant factors GSH and SOD were decreased in SIRT4_KO mice, and the production of oxidative products and lipid peroxidation markers was increased, suggesting that SIRT4 was involved in inflammation and oxidative stress during SAP. Further studies showed that the absence or overexpression of SIRT4 affected the expression level of Hypoxia-inducible factor-1α (HIF-1α) after SAP induction, and regulated the expression of ferroptosis related proteins by mediating HIF-1α/HO-1 pathway. Collectively, our study revealed that SIRT4 plays a protective role in SAP by regulating the HIF-1α/HO-1 pathway to inhibit ferroptosis.

[Predictive value of serum chlorine and interleukin-6 combined with coagulation indexes on severity of severe acute pancreatitis].

OBJECTIVE: To explore the predictive value of combined detection of serum interleukin-6 (IL-6), chloride (Cl-), D-dimer and fibrin degradation products (FDP) for severity of acute pancreatitis (AP). METHODS: From December 2020 to March 2022, 132 AP patients who met the criteria for inclusion were screened for retrospective analysis from 292 AP patients admitted in emergency surgery at the First Affiliated Hospital of Zhengzhou University and they were divided into severe acute pancreatitis (SAP) group and non-SAP group, with 63 in SAP group and 69 in non-SAP group, according to classification criteria. The data including lab results, abdominal doppler ultrasound and chest and abdominal CT, etc. The bedside index for severity in acute pancreatitis (BISAP) score was calculated. Multivariate Logistic regression analysis was carried out to find the risk factors for the severity of AP patients. The receiver operator characteristic curve (ROC) was drawn to judge the clinical predictive value of each factor. RESULTS: A total of 132 AP patients were enrolled. The serum IL-6, D-dimer, FDP levels and the BISAP score in SAP group were significantly higher than those in non-SAP group [serum IL-6 (ng/L): 62.73 (21.54, 187.47) vs. 8.22 (4.13, 14.70), D-dimer (mg/L): 5.36 (2.94, 8.25) vs. 0.94 (0.42, 2.21), FDP (mg/L): 13.54 (6.76, 22.45) vs. 3.20 (2.50, 6.10), BISAP score: 2.00 (1.00, 3.00) vs. 1.00 (0, 2.00), all P < 0.05], while the serum Cl- level was significantly lower than that of non-SAP group (mmol/L: 97.90±4.86 vs. 101.73±4.32, P < 0.05). Multivariate Logistic regression analysis showed that increased levels of IL-6 [odds ratio (OR) = 1.02, 95% confidence interval (95%CI) was 1.01-1.04], D-dimer (OR = 1.21, 95%CI was 1.05-1.40) and decreased Cl- level (OR = 0.88, 95%CI was 0.79-0.98) were risk factors for SAP (all P < 0.05). The ROC curve analysis showed that the area under the ROC curve (AUC) of IL-6, Cl-, D-dimer and FDP combined to predict the severity of AP patients was larger (0.89), and the sensitivity (82.50%) and specificity (85.50%) were higher. CONCLUSIONS: Compared with single index, the combined detection of serum IL-6, Cl-, D-dimer and FDP is more precise in determining the condition of AP.

Thioredoxin-interacting protein deficiency protects against severe acute pancreatitis by suppressing apoptosis signal-regulating kinase 1.

Acute pancreatitis is a common acute inflammatory abdominal disease. When acute pancreatitis progresses to severe acute pancreatitis (SAP), it can lead to systemic inflammation and even multiple organ failure. Thioredoxin-interacting protein (TXNIP) is an important protein involved in redox reactions of the inflammatory response. However, the specific role of TXNIP in SAP remains unclear. In this study, we investigated the role of thioredoxin interacting protein (TXNIP) in acute pancreatitis when induced by high doses of arginine. We found that pancreatic damage and the inflammatory response associated with acute pancreatitis were largely restrained in TXNIP knock-out mice but were enhanced in mice overexpressing TXNIP. Interestingly, the phosphorylation of p38, JNK, and ASK1 diminished in TXNIP-KO mice with pancreatitis in comparison with wild-type mice. The role of oxidative stress in SAP was explored in two models: TXNIP and AVV-TXNIP. TXNIP knockdown or the inhibition of ASK1 by gs-4997 abrogated the increase in p-p38, p-JNK, and p-ASK1 in AR42J cells incubated with L-Arg. The administration of gs-4997 to mice with pancreatitis largely reduced the upregulation of IL-6, IL-1ß, TNF-α, and MCP-1. Systemic inflammatory reactions and injury in the lungs and kidneys were assessed in TXNIP-KO and AVV-TXNIP mice with expected outcomes. In conclusion, TXNIP is a novel mediator of SAP and exerts action by regulating inflammatory responses and oxidative stress via the ASK1-dependent activation of the JNK/p38 pathways. Thus, targeting TXNIP may represent a promising approach to protect against SAP.

Inhibition of macrophage migration inhibitory factor (MIF) suppresses apoptosis signal-regulating kinase 1 to protect against liver ischemia/reperfusion injury.

Background: Hepatic ischemia-reperfusion (I/R) injury is a major complication leading to surgical failures in liver resection, transplantation, and hemorrhagic shock. The role of cytokine macrophage migration inhibitory factor (MIF) in hepatic I/R injury is unclear. Methods: We examined changes of MIF expression in mice after hepatic I/R surgery and hepatocytes challenged with hypoxia-reoxygenation (H/R) insult. Subsequently, MIF global knock-out mice and mice with adeno-associated-virus (AAV)-delivered MIF overexpression were subjected to hepatic I/R injury. Hepatic histology, the inflammatory response, apoptosis and oxidative stress were monitored to assess liver damage. The molecular mechanisms of MIF function were explored in vivo and in vitro. Results: MIF was significantly upregulated in the serum whereas decreased in liver tissues of mice after hepatic I/R injury. MIF knock-out effectively attenuated I/R -induced liver inflammation, apoptosis and oxidative stress in vivo and in vitro, whereas MIF overexpression significantly aggravated liver injury. Via RNA-seq analysis, we found a significant decreased trend of MAPK pathway in MIF knock-out mice subjected hepatic I/R surgery. Using the apoptosis signal-regulating kinase 1 (ASK1) inhibitor NQDI-1 we determined that, mechanistically, the protective effect of MIF deficiency on hepatic I/R injury was dependent on the suppressing of the ASK1-JNK/P38 signaling pathway. Moreover, we found MIF inhibitor ISO-1 alleviate hepatic I/R injury in mice. Conclusion: Our results confirm that MIF deficiency suppresses the ASK1-JNK/P38 pathway and protects the liver from I/R -induced injury. Our findings suggest MIF as a novel biomarker and therapeutic target for the diagnosis and treatment of hepatic I/R injury.

Galangin ameliorates severe acute pancreatitis in mice by activating the nuclear factor E2-related factor 2/heme oxygenase 1 pathway.

Acute pancreatitis (AP) is a common serious acute condition of the digestive system that remains a clinical challenge. Severe acute pancreatitis (SAP) in particular is characterized by high morbidity and mortality. The present study was designed to investigate the protective effect of Galangin (Gal), a natural flavonol obtained from lesser galangal, on L-arginine-induced SAP in mice and in AR42J cells. Amylase and lipase activities were measured and the histopathology of the pancreas, lung, and kidney was evaluated. Inflammation and oxidative stress were assessed using ELISA, western blotting, RT-PCR, and immunohistochemistry. Gal was shown to reduce proinflammatory cytokine production and reactive oxygen species (ROS) generation in vivo and in vitro. L-arginine treatment reduced the expression of components of the nuclear factor E2-related factor 2 (Nrf2) signaling pathway and the downstream protein heme oxygenase-1 (HO-1) in mice, whereas Gal increased their expression. Furthermore, the Nrf2/HO-1 pathway inhibitor brusatol prevented the anti-inflammatory and antioxidant effects of Gal in mice with SAP. Taken together, our results imply that Gal has protective effects in L-arginine-induced SAP that are induced by the upregulation of the Nrf2/HO-1 pathway, which has anti-inflammatory and antioxidant effects. Thus, Gal may represent a promising treatment for SAP.