Histological and lipid peroxidation changes after administration of 2-acetylaminofluorene in a rat liver injury model following selective periportal and pericentral damage

Natural immunoglobulin M initiates an inflammatory response important for both hepatic ischemia reperfusion injury and regeneration in mice

Complement plays a role in both hepatic ischemia reperfusion (IR) injury (IRI) and liver regeneration, but it is not clear how complement is activated in either process. We investigated the role of self-reactive immunoglobulin M (IgM) antibodies in activating complement after hepatic IR and liver resection. Natural IgM antibodies that recognize danger-associated molecular patterns (neoepitopes) activate complement following both hepatic IR and liver resection. Antibody-deficient Rag1^-/- mice were protected from hepatic IRI, but had increased hepatic injury and an impaired regenerative response after 70% partial hepatectomy (PHx). We identified two IgM monoclonal antibodies (mAbs) that specifically reversed the effect of Rag1 deficiency in both models; B4 (recognizes Annexin IV) and C2 (recognizes subset of phospholipids). Focusing on the B4-specific response, we demonstrated sinusoidal colocalization of IgM and C3d in Rag1^-/- mice that were reconstituted with B4 mAb, and furthermore that the Annexin IV neoepitope is specifically and similarly expressed after both hepatic IR and PHx in wild-type (WT) mice. A single-chain antibody construct (scFv) derived from B4 mAb blocked IgM binding and reduced injury post-IR in WT mice, although, interestingly, B4scFv did not alter regeneration post-PHx, indicating that anti-Annexin IV antibodies are sufficient, but not necessary, for the regenerative response in the context of an entire natural antibody repertoire. We also demonstrated expression of the B4 neoepitope in postischemic human liver samples obtained posttransplantation and a corollary depletion in IgM recognizing the B4 and C2 neoepitopes in patient sera following liver transplantation. Conclusion: These data indicate an important role for IgM in hepatic IRI and regeneration, with a similar cross-species injury-specific recognition system that has implications for the design of neoepitope targeted therapeutics. (Hepatology 2018;67:721-735).

Preliminary Characterization, Antioxidant and Hepatoprotective Activities of Polysaccharides from Taishan Pinus massoniana Pollen

The objectives of the present study were to characterize the chemical composition, antioxidant activity and hepatoprotective effect of the polysaccharides from Taishan Pinus massoniana pollen (TPPPS). HPLC analysis showed that TPPPS was an acidic heteropolysaccharide with glucose and arabinose as the main component monosaccharides (79.6%, molar percentage). Fourier transform-infrared spectroscopy (FT-IR) analysis indicated that the spectra of TPPPS displayed infrared absorption peaks characteristic of polysaccharides. In in vitro assays TPPPS exhibited different degrees of dose-dependent antioxidant activities , and this was further verified by suppression of CCl₄-induced oxidative stress in the liver with three tested doses of TPPPS (100, 200, and 400 mg/kg bw) in rats. Pretreatment with TPPPS significantly decreased the levels of alanine aminotransferase (AST), aspartate aminotransferase (ALT), alkaline phosphatase (ALP), lactic dehydrogenase (LDH) and malondialdehyde (MDA) against CCl₄ injuries, and elevated the activities of superoxide dismutase (SOD) as well as glutathione peroxidase (GSH-Px). Histopathological observation further confirmed that TPPPS could protect the liver tissues from CCl₄-induced histological alternation. These results suggest that TPPPS has strong antioxidant activities and significant protective effect against acute hepatotoxicity induced by CCl₄. The hepatoprotective effect may partly be related to its free radical scavenging effect, increasing antioxidant activity and inhibiting lipid peroxidation.

Previous physical exercise alters the hepatic profile of oxidative-inflammatory status and limits the secondary brain damage induced by severe traumatic brain injury in rats

KEY POINTS

An early inflammatory response and oxidative stress are implicated in the signal transduction that alters both hepatic redox status and mitochondrial function after traumatic brain injury (TBI). Peripheral oxidative/inflammatory responses contribute to neuronal dysfunction after TBI Exercise training alters the profile of oxidative-inflammatory status in liver and protects against acute hyperglycaemia and a cerebral inflammatory response after TBI. Approaches such as exercise training, which attenuates neuronal damage after TBI, may have therapeutic potential through modulation of responses by metabolic organs. The vulnerability of the body to oxidative/inflammatory in TBI is significantly enhanced in sedentary compared to physically active counterparts.

ABSTRACT

Although systemic responses have been described after traumatic brain injury (TBI), little is known regarding potential interactions between brain and peripheral organs after neuronal injury. Accordingly, we aimed to investigate whether a peripheral oxidative/inflammatory response contributes to neuronal dysfunction after TBI, as well as the prophylactic role of exercise training. Animals were submitted to fluid percussion injury after 6 weeks of swimming training. Previous exercise training increased mRNA expression of X receptor alpha and ATP-binding cassette transporter, and decreased inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor (TNF)-α and interleukin (IL)-6 expression per se in liver. Interestingly, exercise training protected against hepatic inflammation (COX-2, iNOS, TNF-α and IL-6), oxidative stress (decreases in non-protein sulfhydryl and glutathione, as well as increases in 2',7'-dichlorofluorescein diacetate oxidation and protein carbonyl), which altered hepatic redox status (increases in myeloperoxidase and superoxide dismutase activity, as well as inhibition of catalase activity) mitochondrial function (decreases in methyl-tetrazolium and Δψ, as well as inhibition of citrate synthase activity) and ion gradient homeostasis (inhibition of Na⁺ ,K⁺ -ATPase activity inhibition) when analysed 24 h after TBI. Previous exercise training also protected against dysglycaemia, impaired hepatic signalling (increase in phosphorylated c-Jun NH2-terminal kinase, phosphorylated decreases in insulin receptor substrate and phosphorylated AKT expression), high levels of circulating and neuronal cytokines, the opening of the blood-brain barrier, neutrophil infiltration and Na⁺ ,K⁺ -ATPase activity inhibition in the ipsilateral cortex after TBI. Moreover, the impairment of protein function, neurobehavioural (neuromotor dysfunction and spatial learning) disability and hippocampal cell damage in sedentary rats suggests that exercise training also modulates peripheral oxidative/inflammatory pathways in TBI, which corroborates the ever increasing evidence regarding health-related outcomes with respect to a physically active lifestyle.

Bone marrow-derived mesenchymal stem cells effectively regenerate fibrotic liver in bile duct ligation rat model

Mesenchymal stem cells (MSCs) have attracted lots of attention for the treatment of acute liver failure and end-stage liver diseases. This study aimed at investigating the fundamental mechanism by which bone marrow-derived MSCs (BM-MSCs) induce liver regeneration of fibrotic liver in rats. Rats underwent bile duct ligation (BDL) surgery and four weeks later they were treated with either BM-MSCs (3 × 10(6) cells /rat, once, tail vein injection) or silymarin (100 mg/kg, daily, orally) for four weeks. Liver function tests and hepatic oxidative stress were determined. Hepatic injury and fibrosis were assessed by H and E, Sirus red staining and immunohistochemical expression of α-smooth muscle actin (α-SMA). Hepatocyte growth factor (HGF) and the gene expression of cytokeratin-19 (CK-19) and matrix metalloproteinase-2 (MMP-2) in liver tissue were determined. BDL induced cholestatic liver injury characterized by elevated ALT and AST activities, bilirubin and decreased albumin. The architecture damage was staged as Metavir score: F3, A3. Fibrosis increased around proliferating bile duct as indicated by sirus red staining and α-SMA immunostaining. Fibrogenesis was favored over fibrolysis and confirmed by decreased HGF with increased expression of CK-19, but decreased MMP-2 expression. BM-MSCs treatment restored deteriorated liver functions and restored the histological changes, resolved fibrosis by improving liver regenerative capabilities (P < 0.001), increases in HGF and MMP-2 mRNA and downregulating CK-19 mRNA. Sliymarin, however, induced similar but less prominent effects compared to BM-MSCs. In conclusion, liver regenerative capabilities can be stimulated by BM-MSCs via augmentation of HGF that subsequently up-regulate MMP-2 mRNA while downregulating CK-19 mRNA.

Stem cell-mediated delivery of SPIO-loaded gold nanoparticles for the theranosis of liver injury and hepatocellular carcinoma

The treatment of liver injuries or hepatocellular carcinoma (HCC) has been hindered by the lack of efficient drug delivery. Even with the help of nanoparticles or other synthetic delivering agents, a large portion of the dose is still sequestered in the reticuloendothelial system. As an alternative, adipose-derived mesenchymal cells (AD-MSCs), which have the capability of homing to the injured liver, can be used as a unique carrier for theranostic agents. Theranostic agents must have the capacity for being non-toxic to host cells during transportation, and for timely activation once they arrive at the injury sites. In this study, we loaded AD-MSCs with superparamagnetic iron oxide-coated gold nanoparticles (SPIO@AuNPs) and tested their effects against liver injury and HCC in cells and in mice. SPIO@AuNP is a non-toxic magnetic resonance (MR)-active contrast agent that can generate heat when irradiated with near-infrared laser. Our results showed that SPIO@AuNPs were successfully transfected into AD-MSCs without compromising either cell viability (P > 0.05) or cell differentiability. In vivo MR imaging and histologic analysis confirmed the active homing of AD-MSCs. Upon laser irradiation, the SPIO@AuNP-loaded AD-MSCs could thermally ablate surrounding HCC tumor cells. SPIO@AuNP-loaded AD-MSCs proved a promising theranostic approach for injured liver and HCC.

Dissecting the complement pathway in hepatic injury and regeneration with a novel protective strategy

A novel site-targeted murine complement inhibitor, CR2-CD59, specifically inhibits the terminal membrane attack complex. This inhibitor dissects the complement pathway to protect against liver injury while promoting regeneration in mouse models of liver resection and acute liver failure.

Liver resection is commonly performed under ischemic conditions, resulting in two types of insult to the remnant liver: ischemia reperfusion injury (IRI) and loss of liver mass. Complement inhibition is recognized as a potential therapeutic modality for IRI, but early complement activation products are also essential for liver regeneration. We describe a novel site-targeted murine complement inhibitor, CR2-CD59, which specifically inhibits the terminal membrane attack complex (MAC), and we use this protein to investigate the complement-dependent balance between liver injury and regeneration in a clinical setting of pharmacological inhibition. CR2-CD59 did not impact in vivo generation of C3 and C5 activation products but was as effective as the C3 activation inhibitor CR2-Crry at ameliorating hepatic IRI, indicating that the MAC is the principle mediator of hepatic IRI. Furthermore, unlike C3 or C5 inhibition, CR2-CD59 was not only protective but significantly enhanced hepatocyte proliferation after partial hepatectomy, including when combined with ischemia and reperfusion. Remarkably, CR2-CD59 also enhanced regeneration after 90% hepatectomy and improved long-term survival from 0 to 70%. CR2-CD59 functioned by increasing hepatic TNF and IL-6 levels with associated STAT3 and Akt activation, and by preventing mitochondrial depolarization and allowing recovery of ATP stores.

Snailase preparation of ginsenoside M1 from protopanaxadiol-type ginsenoside and their protective effects against CCl4-induced chronic hepatotoxicity in mice

To investigate the protective effects of protopanaxadiol-type ginsenoside (PDG) and its metabolite ginsenoside M1 (G-M1) on carbon tetrachloride (CCl₄)-induced chronic liver injury in ICR mice, we carried out conversion of protopanaxadiol-type ginsenosides to ginsenoside M1 using snailase. The optimum time for the conversion was 24 h at a constant pH of 4.5 and an optimum temperature of 50 °C. The transformation products were identified by high-performance liquid chromatography and electrospray ion-mass spectrometry. Subsequently, most of PDG was decomposed and converted into G-M1 by 24 h post-reaction. During the study on hepatoprotective in a mice model of chronic liver injury, PDG or G-M1 supplement significantly ameliorated the CCl₄-induced liver lesions, lowered the serum levels of select hepatic enzyme markers (alanine aminotransferase, ALT, and aspartate aminotransferase, AST) and malondialdehyde and increased the activity of superoxide dismutase in liver. Histopathology of the liver tissues showed that PDG and G-M1 attenuated the hepatocellular necrosis and led to reduction of inflammatory cell infiltration. Therefore, the results of this study show that PDG and G-M1 can be proposed to protect the liver against CCl₄-induced oxidative injury in mice, and the hepatoprotective effect might be attributed to amelioration of oxidative stress.

A complement-dependent balance between hepatic ischemia/reperfusion injury and liver regeneration in mice

Massive liver resection and small-for-size liver transplantation pose a therapeutic challenge, due to increased susceptibility of the remnant/graft to ischemia reperfusion injury (IRI) and impaired regeneration. We investigated the dual role of complement in IRI versus regeneration in mice. Complement component 3 (C3) deficiency and complement inhibition with complement receptor 2-complement receptor 1-related protein y (CR2-Crry, an inhibitor of C3 activation) provided protection from hepatic IRI, and while C3 deficiency also impaired liver regeneration following partial hepatectomy (PHx), the effect of CR2-Crry in this context was dose dependent. In a combined model of IRI and PHx, either C3 deficiency or high-dose CR2-Crry resulted in steatosis, severe hepatic injury, and high mortality, whereas low-dose CR2-Crry was protective and actually increased hepatic proliferative responses relative to control mice. Reconstitution experiments revealed an important role for the C3a degradation product acylation-stimulating protein (ASP) in the balance between inflammation/injury versus regeneration. Furthermore, liver regeneration was dependent on the putative ASP receptor, C5L2. Several potential mechanisms of hepatoprotection and recovery were identified in mice treated with low-dose CR2-Crry, including enhanced IL-6 expression and STAT3 activation, reduced hepatic ATP depletion, and attenuated oxidative stress. These data indicate that a threshold of complement activation, involving ASP and C5L2, promotes liver regeneration and suggest a balance between complement-dependent injury and regeneration.

Therapeutic value of melatonin in an experimental model of liver injury and regeneration

Melatonin has marked antioxidant properties. The aim of the present study was to evaluate the therapeutic effect of melatonin on acute liver injury induced in rats by carbon tetrachloride (CCl4), allyl alcohol (AA) and their combination. A total of 108 male Wistar rats were divided into 12 experimental groups according to their treatment regimen (n = 5-10 rats in each group). Melatonin (100 mg/kg body weight, BW) was administered 6 hr (a) after a single dose of CCl4 (intragastrically 0. 66 mL/kg BW diluted 1:1 v/v with corn oil); (b) a single dose of AA (intraperitonealy, 0.62 mmol/kg BW 1:50 v/v in 0.9% saline solution); and (c) a combination of the above substances. Rats were sacrificed at 24 and 48 hr post-toxin administration and the therapeutic effect of melatonin was investigated by assessment of histopathological changes and lipid peroxidation alterations determined by measuring tissue malondialdehyde plus 4-hydroxy-nonenal (MDA + 4-HNE), plasma MDA and plasma levels of liver enzymes. The levels of a key antioxidant, glutathione (GSH), were measured in liver tissue homogenates. Hepatic necrosis was significantly reduced in the melatonin-treated rats 48 hr after administration of CCl4, AA and CCl4 + AA. The levels of hepatic enzymes in plasma were found to be significantly reduced at 24 and 48 hr in the CCl4 + AA treated rats after melatonin administration. Additionally, MDA and MDA + 4-HNE concentrations were significantly reduced at 24 and 48 hr time-points in all groups that received melatonin. GSH levels were decreased in liver after the toxic substances administration, whereas melatonin reversed this effect. In conclusion, a single dose of melatonin decreased hepatic injury induced by CCl4, AA and CCl4 + AA. The inhibition of the oxidative stress and therefore lipid peroxidation by melatonin in CCl4 and AA administered animals, may constitute the protective mechanism of melatonin against acute liver injury.

ATTENUATION OF ENDOTOXIN-INDUCED OXIDATIVE STRESS AND MULTIPLE ORGAN INJURY BY 3,4-METHYLENEDIOXYPHENOL IN RATS

Endotoxin is a potent inducer of lipid peroxidation (LPO), which is associated with the development of endotoxemia. 3,4-Methylenedioxyphenol (sesamol) is one of the sesame oil lignans with a high anti-LPO effect. Whether sesamol can attenuate endotoxin-induced LPO and multiple organ injury is unknown. After a dose response for sesamol in endotoxin-challenged rats was established, experiments were conducted to assess its effects on hydroxyl radical, peroxynitrite, and superoxide anion counts, activities of superoxide dismutase, catalase, and glutathione peroxidase, as well as the production of nitric oxide (NO) and the expression of inducible NO synthase. In addition, the effects of sesamol on endotoxin-induced hepatic and renal injuries were assessed. Sesamol (a) dose dependently reduced serum LPO inendotoxin-challenged rats, (b) decreased hydroxyl radical and peroxynitrite, but not superoxide anion counts, (c)increased the activities of superoxide dismutase, catalase, and glutathione peroxidase in endotoxin-treated rats, (d)reduced NO production and inducible NO synthase expression, and (e) attenuated hepatic and renal injuries induced by endotoxin in rats. We concluded that sesamol might protect against organ injury by decreasing NO-associated LPO in endotoxemic rats.

The effect of N-acetylcysteine on pulmonary lipid peroxidation and tissue damage

BACKGROUND

We aimed to investigate the effect of N-acetylcysteine (NAC) on pulmonary lipid peroxidation and tissue damage in experimental obstructive jaundice (OJ) stimulated by lipopolysaccharide (LPS) in this study.

MATERIALS AND METHODS

We randomized 40 rats into five groups. Group A: Sham (n = 8); group B: OJ (n = 8); group C: OJ + lipopolysaccharide (LPS; n = 8); group D: OJ + NAC + LPS (n = 8); group E: OJ + LPS + NAC (n = 8). OJ was performed by common bile duct ligation and division in all groups except the sham group. At the fifth day, the rats were jaundiced. At the fifth day of OJ, LPS was injected 10 mg/kg intraperitoneally to the rats and at the tenth day, the rats were sacrificed in group C. In group D; at the fifth day of OJ, NAC was started 100 mg/kg subcutaneously and the same dose NAC injection repeated every day for 5 days. At the tenth day of OJ, LPS was injected 10 mg/kg intraperitoneally to the rats and then after 6 h they were sacrificed. In group E; 10 mg/kg LPS was administered intraperitoneally at fifth day of OJ and after then NAC was started 100 mg/kg subcutaneously and the same dose NAC injection repeated every day for 5 days and at the tenth day, the rats were sacrificed. Tissue samples were harvested through a midline incision, and lungs were resected and examined histopathologically and immunohistochemically for tissue damage scoring. The blood was taken by cardiac puncture and malondialdehyde (MDA), myeloperoxidase (MPO), and levels of total antioxidant status were detected with biochemical methods to evaluate lung tissue damage.

RESULTS

Increase in lung and serum MDA and MPO levels, as well as decrease in total antioxidant status, were observed in groups B and C when compared with the sham group (P = 0.0001, for each comparison). Furthermore, the lung tissue damage was observed in the same groups by histopathological examination when compared with sham group. There was significant decrease at serum and lung MPO and MDA levels after the NAC application in groups D and E, when compared with group C (P = 0.0001, for each comparison). Antioxidant status in groups D and E were increased in the presence of NAC (P = 0.0001, for each comparison). Lung histology was prevented relatively in group D when compared with groups B and C.

CONCLUSION

Results of the study indicate that NAC has protective effect on pulmonary lipid peroxidation and tissue damage before and after LPS administration.