Zuojin Liu

Protective effect of glutamine-enriched early enteral nutrition on intestinal mucosal barrier injury after liver transplantation in rats

BACKGROUND The effect of glutamine-enriched early enteral nutrition (Gln-EEN) on intestinal mucosal barrier injury after liver transplantation (LT) remains uncertain. METHODS The Wistar-to-Wistar rat LT model was used to explore the protective effect of Gln-EEN. Morphologic changes of intestinal mucosa, levels of intestinal malondialdehyde and secretory immunoglobulin (sIgA), plasma endotoxin, D-lactic acid, serum tumor necrosis factor-alpha (TNF-alpha), rates of bacterial translocation, and expression of intestinal nuclear factor-kappaB, TNF-alpha, and intercellular adhesion molecule-1 were determined. RESULTS After LT, intestinal mucosa was damaged seriously. At 12, 24, and 48 hours posttransplantation, levels of intestinal sIgA were decreased; levels of malondialdehyde, endotoxin, D-lactic acid, and TNF-alpha, the ratio of bacterial translocation, and the expression of intestinal nuclear factor-kappaB, TNF-alpha, and intercellular adhesion molecule-1 all were increased. However, changes in earlier-mentioned parameters in recipients treated with Gln-EEN were attenuated remarkably at 24 to 48 hours. CONCLUSIONS Our data show that Gln-EEN is a potent protectant against intestinal mucosal barrier injury after LT.

Suppression of histone deacetylase 11 promotes expression of IL-10 in Kupffer cells and induces tolerance following orthotopic liver transplantation in rats.

BACKGROUND Suppression of histone deacetylase 11 (HDAC11) can promote IL-10 expression in mouse macrophages RAW264.7 and induce immune tolerance. This study is to further investigate the role of HDAC11 in tolerance induction via Kupffer cells (KCs) following orthotopic liver transplantation (OLT) in rats. MATERIALS AND METHODS KCs isolated from BALB/c mice were divided into pHDAC11, adHDAC11, and pCV group (treated with HADC11-shRNA, adenovirus encoding HDAC11, and control vector, respectively). IL-10 expression was determined after lipopolysaccharide treatment. The expression of MHC-II and co-stimulatory molecules on KCs surface was evaluated by flow cytometry. T cell proliferation was measured by [(3)H]-thymidine incorporation after culturing with aforementioned three groups, treated KCs, respectively. OLT was performed in rats after Ad-HDAC11 and pHDAC11 treatment. Blood samples were collected for biochemical studies, and postoperative survival was examined. RESULTS IL-10 expression was inhibited and promoted by Ad-HDAC11 and HDAC11-shRNA in KCs, respectively. MHC-II and co-stimulatory molecules on KCs surface as well as T cell proliferation were significantly inhibited and induced in pHDAC11 and Ad-HDAC11 compared with pCV, respectively. Serum IL-2, TNF-α, and IFN-γ levels were significantly lower in pHDAC11 and higher in Ad-HDAC11 compared with pCV, respectively, while IL-4 and IL-10 were the reverse. Postoperative survival, liver function, and histology were different among the three groups. CONCLUSIONS Suppression of HDAC11 can promote IL-10 expression in KCs and induce tolerance following OLT in rats. Consequently, HDAC11 may be a key component of this immune regulation system and a promising target for development of novel drugs of gene therapy for inducing tolerance in clinical liver transplantation.

The role of Kupffer cells in hepatic diseases.

&NA; Kupffer cells (KCs) constitute 80–90% of the tissue macrophages present in the body. Essential to innate and adaptive immunity, KCs are responsible for the swift containment and clearance of exogenous particulates and immunoreactive materials which are perceived as foreign and harmful to the body. Similar to other macrophages, KCs also sense endogenous molecular signals that may result from perturbed homeostasis of the host. KCs have been implicated in host defense and the pathogenesis of various hepatic diseases, including endotoxin tolerance, liver transplantation, nonalcoholic fatty liver disease, and alcoholic liver disease. In this review, we summarized some novel findings associated with the role of KCs in hepatic diseases, such as the origin and mechanisms KCs polarization, molecular basis for caspase‐1 activation called “non‐canonical inflammasome pathway” involving the cleavage of Gsdmd by caspase‐11, the important role of microRNA in liver transplantation, and so on. A better understanding of KCs biological characteristics and immunologic function in liver homeostasis and pathology may pave the way to investigate new diagnostic and therapeutic approaches for hepatic diseases. HighlightsCytoplasmic LPS can activate macrophage via TLR4‐independent pathway that results in activation of the enzyme caspase‐11.The negative regulators associated with endotoxin tolerance in KCs include IRAK‐M, SHIP1, and SCOS1 and Twist‐2.KCs are responsible for the initiation of the pro‐inflammatory response in IRI.KCs are involved in liver immune tolerance through inducing apoptosis of T cells.KCs release IL‐1&bgr; that promotes development of NAFLD by activating TLR4, TLR9 and NLRP3 inflammasome pathways.

Augmenter of liver regeneration promotes hepatic regeneration depending on the integrity of Kupffer cell in rat small-for-size liver transplantation

BACKGROUND Augmenter of liver regeneration (ALR) can promote hepatocyte proliferation and thereby augment liver mass restoration. This study was performed to further explore the mechanism of ALR on liver regeneration in small-for-size liver transplanted rats. METHODS Donor Sprague-Dawley rats were divided into a Kupffer cell (KC)-depleted group (pretreated with GdCl3) and KC-competent group and then further divided into two subgroups: the ALR subgroup (infused with 100 μg/kg ALR through the portal vein) and non-ALR subgroup. Only the median lobe was retained to establish the small-for-size liver transplantation model. Ten rats from each subgroup were used for the 7 d survival study. In addition, the nuclear factor κB activity, reperfusion injury, regeneration of the remnant liver, and tumor necrosis factor α and interleukin 6 expression levels were evaluated. RESULTS ALR could accelerate graft regeneration by increasing nuclear factor κB activity to induce tumor necrosis factor α and interleukin 6 expression in the KC-competent rats, which resulted in a higher 7 d survival rate. CONCLUSIONS ALR could enhance the hepatocellular proliferation of small-for-size liver grafts, and these effects appeared to deeply depend on the integrity of KCs.

Knockdown of interleukin-2 by shRNA-mediated RNA interference prolongs liver allograft survival.

Interleukin-2 (IL-2) plays a central role in T-cell activation, expansion, and homeostasis. The failure of IL-2 biosynthesis may play a critical role in tolerance induction. We tested the effect of IL-2 blockade by short hairpin RNA (shRNA) on regulating acute rejection in rat liver transplantation. To this end, we successfully designed and selected an effective interference plasmid, pIL-2B. The IL-2 mRNA expression level in the pIL-2B group was one-fifth of that in the no transfection group. Lewis to BN orthotopic liver transplant model was used to explore the effect of knockdown IL-2 by shRNA in vivo. Recipients treated with pIL-2-shRNA survived longer (median survival time of 16 d range 7-21 d) than those with empty vector (11; range 5-13) or saline (9; range 5-13) (P<0.05), and was inferior to those with CsA (24; range 13-36, P<0.05). The IL-2-shRNA attenuated acute rejection with decreased apoptosis of hepatocytes and reduced cytokine production of IL-2, tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) in the graft. Our results suggest that IL-2 targeting using RNA interference approach may be of potential interest in organ transplantation.

Blockade of inducible costimulator pathway to prevent acute rejection in rat liver transplantation

BACKGROUND The role of inducible costimulator (ICOS) in transplantation immunity remains unclear. METHODS A Lewis-to-Brown-Norway (BN) rat liver transplant model was used to explore the effect of ICOS blockade by small interference RNA. Recipient survival rate, number of CD25/ICOS-positive cells, ICOS mRNA and protein levels, and interferon-gamma and tumor-necrosis factor-alpha levels were determined. RESULTS Recipient survival was significantly prolonged in rats treated with RNA interference. On day 7 after transplantation, there was a diminished frequency of CD25/ICOS-positive cells and an increased frequency of apoptotic T cells. Furthermore, we found that ICOS blockade could inhibit mRNA and protein expression of ICOS, decrease plasma levels of interferon-gamma and tumor-necrosis factor-alpha, suppress cell infiltration into grafts, and promote tolerance in the interference group. CONCLUSIONS Our data demonstrate that RNA interference is a potent tool to down-modulate ICOS expression and protect allografts from acute rejection.

Monoacylglycerol Lipase: A Novel Potential Therapeutic Target and Prognostic Indicator for Hepatocellular Carcinoma

Monoacylglycerol lipase (MAGL) is a key enzyme in lipid metabolism that is demonstrated to be involved in tumor progression through both energy supply of fatty acid (FA) oxidation and enhancing cancer cell malignance. The aim of this study was to investigate whether MAGL could be a potential therapeutic target and prognostic indicator for hepatocellular carcinoma (HCC). To evaluate the relationship between MAGL levels and clinical characteristics, a tissue microarray (TMA) of 353 human HCC samples was performed. MAGL levels in HCC samples were closely linked to the degree of malignancy and patient prognosis. RNA interference, specific pharmacological inhibitor JZL-184 and gene knock-in of MAGL were utilized to investigate the effects of MAGL on HCC cell proliferation, apoptosis, and invasion. MAGL played important roles in both proliferation and invasion of HCC cells through mechanisms that involved prostaglandin E2 (PGE2) and lysophosphatidic acid (LPA). JZL-184 administration significantly inhibited tumor growth in mice. Furthermore, we confirmed that promoter methylation of large tumor suppressor kinase 1 (LATS1) resulted in dysfunction of the Hippo signal pathway, which induced overexpression of MAGL in HCC. These results indicate that MAGL could be a potentially novel therapeutic target and prognostic indicator for HCC.

Advantages of Promoting Interleukin-10 by Silence of Histone Deacetylase 11 in Inducing Tolerance in Orthotopic Liver Transplantation in Rats

AIMS The aims of this study were to study the role of histone deacetylase 11 (HDAC11) in tolerance induction in orthotopic liver transplantation (OLT) in rats and to assess the advantages of gene therapy over the immunosuppressant FK506. METHODS Recipients were assigned to an acute rejection group (AcR; group I), an FK506 intervention group (group II), and a tolerance group (group III). Acute rejection (AcR) was graded by the Banff scheme and we examined postoperative survival. The messenger RNA (mRNA) and protein expressions of histone deacetylase 11 (HDAC11) and interleukin (IL) 10 in liver tissue were detected using real-time polymerase chain reaction (PCR) and Western blots, respectively. Plasma levels of tumor necrosis factor (TNF)-α, IL-2, and IL-10 were measured using enzyme-linked immunosorbent Assays. RESULTS Group I displayed severe, Group II had less, and Group III had no evidence of AR. The survivals among Group III were longer than those in Group I and Group II. IL-10 expression was promoted by HDAC11-shRNA at 7 days after OLT. Serum IL-2 and TNF-α levels were significantly lower among Group III compared with Groups I and II, whereas IL-10 showed the opposite result. CONCLUSIONS Silence of HDAC11 promotes IL-10 expression and leads to tolerance following OLT in rats. Thus HDAC11 is a promising target for gene therapy to induce tolerance with advantages over immunosuppressive drugs.

NBD peptides protect against ischemia reperfusion after orthotopic liver transplantation in rats.

BACKGROUND NBD (NEMO binding domain) peptides could selectively inhibit the inflammation induced NF-κB activity, while sparing the protective functions of basal NF-κB activity. The aim of this study was to determine whether NBD peptides inhibited the transcriptional activity of nuclear factor-κB (NF-κB) during liver transplant ischemia-reperfusion injury (IRI), without affecting its basal function. MATERIALS AND METHODS Sprague Dawley (SD) rats were performed orthotropic liver transplantation according to the Kamada technique. Donors were given NBD peptides (8 mg/kg, intraperitoneal) 2 h before surgery (n = 24) and the controls were treated with the same volume of physiologic saline (n = 24). An additional 16 animals in normal condition (did not undergo any surgery) were also divided into two groups and given the same treatment as above to assess the effect of NBD peptides on basal function. We analyzed levels of alanine aminotransferase (ALT), tumor necrosis factor (TNF-α), IKK (IκB kinase) complex phosphorylation, IκBα degradation, NF-κB transcriptional activity, apoptosis, and performed a morphologic study of liver tissues at 3, 6, and 24 h after portal vein reperfusion and in normal condition (n = 8). RESULTS Pretreatment with NBD peptides significantly improved liver function, attenuating liver parenchymal cell damage, apoptosis by down-regulating TNF-α level, inhibiting IKK complex phosphorylation, IκBα degradation, and NF-κB transcriptional activity, but had no effect in normal condition. CONCLUSION NBD peptides attenuated hepatic IRI by preventing NF-κB activation, without affecting basal NF-κB activity.

Bone marrow stromal cells attenuate LPS-induced mouse acute liver injury via the prostaglandin E 2-dependent repression of the NLRP3 inflammasome in Kupffer cells

The nucleotide-binding and oligomerization domain-like receptor 3 (NLRP3) inflammasome participates in the pathogenesis of acute liver injury during sepsis. Bone marrow mesenchymal stem cells (BMSCs) attenuate sepsis through prostaglandin E 2 (PGE2) by increasing the interleukin-10 (IL-10) production of macrophages; moreover, NLRP3 inflammasome assembly is effectively regulated by IL-10 during infection. Whether BMSCs have an effect on the activation of the NLRP3 inflammasome and its underlying mechanism is unclear. Administering of BMSCs to mice or KCs after LPS stimulating have improved liver function and reduced activation of NLRP3 inflammasome in KCs. The beneficial effect of BMSCs was enhanced by over-expression of PGE2 and eliminated by silence of PGE2. Additionally, The IL-10 levels in the serum and supernatant were increased by given BMSCs and further increase by PGE2 over-expressed BMSCs, but decreased markedly by PGE2 silenced BMSCs. Furthermore, extracellular signal-regulated kinase 1 (ERK1) inhibitor reduced IL-10 production in KCs and blocked the inhibitory effect of PGE2 on the activation of the NLRP3 inflammasome. Our data reveal a novel mechanism of BMSC-mediated suppression of the activation of KCs through the secretion of PGE2 by BMSCs, which promotes KCs to secrete IL-10, leading to the inhibition of the NLRP3 inflammasome in KCs.