N-acetylcysteine protects hepatocytes from hypoxia-related cell injury

Chemical approaches targeting the hurdles of hepatocyte transplantation: mechanisms, applications, and advances

Hepatocyte transplantation (HTx) has been a novel cell-based therapy for severe liver diseases, as the donor livers for orthotopic liver transplantation are of great shortage. However, HTx has been confronted with two main hurdles: limited high-quality hepatocyte sources and low cell engraftment and repopulation rate. To cope with, researchers have investigated on various strategies, including small molecule drugs with unique advantages. Small molecules are promising chemical tools to modulate cell fate and function for generating high quality hepatocyte sources. In addition, endothelial barrier, immune responses, and low proliferative efficiency of donor hepatocytes mainly contributes to low cell engraftment and repopulation rate. Interfering these biological processes with small molecules is beneficial for improving cell engraftment and repopulation. In this review, we will discuss the applications and advances of small molecules in modulating cell differentiation and reprogramming for hepatocyte resources and in improving cell engraftment and repopulation as well as its underlying mechanisms.

4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) exposure induces hepatotoxicity and nephrotoxicity - role of oxidative stress, mitochondrial dysfunction and pathways of cytotoxicity

Objective

Bisphenol A (BPA) is a ubiquitous pollutant worldwide and 4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) is considered a major active metabolite of BPA with a wide range of potent toxicological properties. However, its adverse outcome pathway (AOP) on the hepatic and renal system has not yet been explored.

Methods

Hence, the current study evaluated its effect on cell survival, oxidative stress, and apoptosis. In addition, the influence of signalling pathways on cytotoxicity and ROS generating enzymes (NOX2 and XO) on oxidative stress was explored by siRNA knockdown experiments. Further, its molecular interaction with SOD, CAT, and HSA (molecular docking and dynamics) was evaluated and validated with spectroscopy (fluorescence and FTIR) based methods.

Results

The outcome indicates that MBP exposure dose dependently increased the cytotoxic response, oxidative stress, and apoptosis in both hepatocytes and kidney cells. Further, MAPK signalling pathways and oxidative stress influenced the overall cytotoxic response in both cells. In addition, the stimulatory (NOX2 and XO) and inhibitory (SOD and CAT) effects of MBP were observed, along with a robust interaction with HSA.

Conclusions

The overall observation illustrates that MBP exposure adversely impacts hepatic and renal cells through oxidative stress and relevant molecular pathways which may connect the missing links during risk assessment of BPA.

Ex vivo gene editing and cell therapy for hereditary tyrosinemia type 1

BACKGROUND

We previously demonstrated the successful use of in vivo CRISPR gene editing to delete 4-hydroxyphenylpyruvate dioxygenase (HPD) to rescue mice deficient in fumarylacetoacetate hydrolase (FAH), a disorder known as hereditary tyrosinemia type 1 (HT1). The aim of this study was to develop an ex vivo gene-editing protocol and apply it as a cell therapy for HT1.

METHODS

We isolated hepatocytes from wild-type (C57BL/6J) and Fah-/- mice and then used an optimized electroporation protocol to deliver Hpd-targeting CRISPR-Cas9 ribonucleoproteins into hepatocytes. Next, hepatocytes were transiently incubated in cytokine recovery media formulated to block apoptosis, followed by splenic injection into recipient Fah-/- mice.

RESULTS

We observed robust engraftment and expansion of transplanted gene-edited hepatocytes from wild-type donors in the livers of recipient mice when transient incubation with our cytokine recovery media was used after electroporation and negligible engraftment without the media (mean: 46.8% and 0.83%, respectively; p=0.0025). Thus, the cytokine recovery medium was critical to our electroporation protocol. When hepatocytes from Fah-/- mice were used as donors for transplantation, we observed 35% and 28% engraftment for Hpd-Cas9 ribonucleoproteins and Cas9 mRNA, respectively. Tyrosine, phenylalanine, and biochemical markers of liver injury normalized in both Hpd-targeting Cas9 ribonucleoprotein and mRNA groups independent of induced inhibition of Hpd through nitisinone, indicating correction of disease indicators in Fah-/- mice.

CONCLUSIONS

The successful liver cell therapy for HT1 validates our protocol and, despite the known growth advantage of HT1, showcases ex vivo gene editing using electroporation in combination with liver cell therapy to cure a disease model. These advancements underscore the potential impacts of electroporation combined with transplantation as a cell therapy.

Bisphenol A (BPA) exposure aggravates hepatic oxidative stress and inflammatory response under hypertensive milieu - Impact of low dose on hepatocytes and influence of MAPK and ER stress pathways

Human exposure to the hazardous chemical, Bisphenol A (BPA), is almost ubiquitous. Due to the prevalence of hypertension (CVD risk factor) in the aged human population, it is necessary to explore its adverse effect in hypertensive subjects. The current study exposed the Nω-nitro-l-arginine methyl ester (L-NAME) induced hypertensive Wistar rats to human exposure relevant low dose of BPA (50 μg/kg) for 30 days period. The liver biochemical parameters, histopathology, immunohistochemistry, gene expression (RT-qPCR), trace elements (ICP-MS), primary rat hepatocytes cell culture and metabolomic (1H NMR) assessments were performed. Results illustrate that BPA exposure potentiates/aggravates hypertension induced tissue abnormalities (hepatic fibrosis), oxidative stress, ACE activity, malfunction of the antioxidant system, lipid abnormalities and inflammatory factor (TNF-α and IL-6) expression. Also, in cells, BPA increased ROS generation, mitochondrial dysfunction and lipid peroxidation without any impact on cytotoxicity and caspase 3 and 9 activation. Notably, BPA exposure modulate lipid metabolism (cholesterol and fatty acid) in primary hepatocytes. Finally, the influence of ERK1/2, p38MAPK, ER stress and oxidative stress during relatively high dose of BPA elicited cytotoxicity was observed. Therefore, a precise hazardous risk investigation of BPA exposure in hypertensive populations is highly recommended.

The association between N-acetylcysteine treatment and hepatic healing in patients with non-acetaminophen-induced liver injury in pediatric intensive care: A single-center retrospective study

OBJECTIVE

The aim of this study was to determine the association between the use of intravenous N-acetylcysteine (NAC) and hepatic healing in pediatric intensive care unit (PICU) patients with non-acetaminophen-induced hepatic injury, except for acute liver failure.

METHODS

The data of patients who received intravenous NAC as adjuvant therapy for transaminase levels more than sixfold normal values during their PICU stay between 2010 and 2014 were retrospectively collected from the medical records database. The patients who did not receive NAC with elevated transaminase levels during their PICU stay between 2014 and 2018 were also collected as the standard of care (SOC) cohort.

RESULTS

More than 50% of the liver injuries were secondary to acute hypoxia, hypotension, sepsis, and inflammation. The median number of elevated transaminase period (ETP) days of the NAC and SOC groups were 5 (IQR: 4) and 4 (IQR: 4), respectively (p = 0.17). There was no significant difference between the groups in terms of minimum and maximum laboratory values during ETP. There was no significant difference in terms of ETP and maximum ALT levels between the NAC and SOC groups in the hypoxia-hypotension subgroup.

CONCLUSION

This study did not show an association between indirect measures of hepatic healing and post-insult use of NAC in pediatric liver injury in the PICU setting.

Yi-Qi-Jian-Pi formula modulates the PI3K/AKT signaling pathway to attenuate acute-on-chronic liver failure by suppressing hypoxic injury and apoptosis in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Acute-on-chronic liver failure (ACLF) is a key complication of chronic hepatitis, with a relatively high mortality rate and limited treatment options, which dramatically threatens human lives. Yi-Qi-Jian-Pi formula (YQJPF) is a herbal compound commonly used to treat liver failure.

AIM OF THE STUDY

The purpose of this research is to discuss the potential molecular biological effect and mechanism of YQJPF in ACLF.

MATERIALS AND METHODS

In this study, we created a rat model of ACLF by CCl₄-, LPS- and D-Galactosamine (D-Gal) and an in vitro model of LPS-induced hepatocyte damage. The specific components of YQJPF and potential mechanism were explored based on bioinformatics analyses. Furthermore, we verified the effect of YQJPF on ACLF using immunohistochemistry, RT-qPCR, western blotting, and flow cytometry.

RESULTS

Our research demonstrated that, after YQJPF treatment, hepatocyte injury in rats was relieved. Bioinformatics analysis showed that PI3K/AKT, HIF-1, mitochondrial apoptosis pathways played prominent roles. YQJPF promoted HIF-1α protein expression and exerted protective effects against hypoxic injury, simultaneously reducing mitochondrial ROS production, suppressing hepatocyte apoptosis. Furthermore, we showed that YQJPF accelerates PI3K/AKT pathway activation, a known broad-spectrum inhibitor of PI3K. LY294002, which was used for reverse verification, suppressed the effect of YQJPF on hypoxic injury and ROS-mediated hepatocyte apoptosis.

CONCLUSIONS

YQJPF ameliorates liver injury by suppressing hypoxic injury and ROS-mediated hepatocyte apoptosis by modulating the PI3K/AKT pathway.

Establishment of a hypobaric hypoxia-induced cell injury model in PC12 cells

To construct a hypobaric hypoxia-induced cell injury model. Rat pheochromocytoma PC12 cells were randomly divided into control group, normobaric hypoxia group and hypobaric hypoxia group. The cells in control group were cultured at normal condition, while cells in other two groups were cultured in normobaric hypoxia and hypobaric hypoxia conditions, respectively. CCK-8 method was used to detect cell viability to determine the optimal modeling conditions like the oxygen concentration, atmospheric pressure and low-pressure hypoxia time. The contents of lactate dehydrogenase (LDH), superoxide dismutase (SOD) and malondialdehyde (MDA) were detected by microplate method. The apoptosis ratio and cell cycle were analyzed by flow cytometry. The hypobaric hypoxia-induced cell injury model can be established by culturing for 24 h at 1% oxygen concentration and 41 kPa atmospheric pressure. Compared with the control group and normobaric hypoxia group, the activity of LDH and the content of MDA in hypobaric hypoxia group were significantly increased, the activity of SOD was decreased, the percentage of apoptosis was increased (all <0.05), and the cell cycle was arrested in G0/G1 phase. A stable and reliable cell injury model induced by hypobaric hypoxia has been established with PC12 cells, which provides a suitable cell model for the experimental study on nerve injury induced by hypoxia at high altitude.

Use of N-Acetylcysteine for Clozapine-Induced Acute Liver Injury: A Case Report and Literature Review

Purpose: To report a case of clozapine-induced hepatotoxicity managed with intravenous (IV) N-acetylcysteine (NAC) and summarize the available literature. Summary: A 46-year-old woman with history of bipolar disorder with psychotic features presented to the intensive care unit with asterixis and elevations in liver enzymes. The patient had been initiated on risperidone, clozapine, and lithium approximately 1 month prior to admission. After ruling out other possible non-drug etiologies, clozapine was suspected as the likeliest cause of the acute liver injury. Her acute liver injury was managed with the discontinuation of all antipsychotics, administration of IV NAC, and other standard of care supportive measures. Conclusion: Although clozapine has been associated with hepatitis and acute liver failure, there are no reports of NAC used in the management of clozapine-induced hepatotoxicity. NAC was used in our patient after considering the potential benefit and limited adverse effects. The role of NAC in non-acetaminophen-induced acute liver failure remains promising, but more research is warranted.

N-acetylcysteine maintains penile length and erectile function in bilateral cavernous nerve crush rat model by reducing penile fibrosis

Penile length shortening and erectile dysfunction are common complications after radical prostatectomy. Various methods have been used to maintain erectile function, but less attention has been paid to preserving penis length. N-acetylcysteine (NAC) has the effect of antioxidation and antifibrotic, which may be beneficial to improve those postoperative complications. This study investigated the effect of NAC on maintaining the penile length and the erectile function after bilateral cavernous nerve crush (BCNC) and its underlying mechanism. Twenty-four male rats were randomly divided into three groups: control group, BCNC group, and BCNC + NAC group. NAC or equal volume of saline was daily administrated by intragastric gavage for 4 weeks. The initial and end penile lengths were measured. Intracavernosal pressure/mean arterial pressure (ICP/MAP) ratio was calculated to assess erectile function. Hematoxylin–eosin staining, Masson's trichrome staining, immunohistochemistry, and Western blot were performed to explore cellular and molecular changes of the penis. Compared to the BCNC group, the penile length, ICP/MAP ratio and smooth muscle/collagen ratio in the BCNC + NAC group were improved significantly (all P < 0.05), and the expressions of endothelial nitric oxide synthase, α-smooth muscle actin, glutathione, and glutathione peroxidase 1 were significantly increased after NAC treated (all P < 0.05), along with the decreased expressions of hypoxia-inducible factor-1α, transforming growth factor-β1, collagen I, collagen III, collagen IV, malonaldehyde, and lysine oxidase (all P < 0.05). This study demonstrated that NAC could maintain penile length and partly improve erectile function. Possible mechanism is directly and/or indirectly related to antihypoxic and antifibrosis.