Relationship between TH1/TH2 cytokines and immune tolerance in liver transplantation in rats

The role of natural killer T cells in liver transplantation

Natural killer T cells (NKTs) are innate-like lymphocytes that are abundant in the liver and participate in liver immunity. NKT cells express both NK cell and T cell markers, modulate innate and adaptive immune responses. Type I and Type II NKT cells are classified according to the TCR usage, while they recognize lipid antigen in a non-classical major histocompatibility (MHC) molecule CD1d-restricted manner. Once activated, NKT cells can quickly produce cytokines and chemokines to negatively or positively regulate the immune responses, depending on the different NKT subsets. In liver transplantation (LTx), the immune reactions in a series of processes determine the recipients' long-term survival, including ischemia-reperfusion injury, alloresponse, and post-transplant infection. This review provides insight into the research on NKT cells subpopulations in LTx immunity during different processes, and discusses the shortcomings of the current research on NKT cells. Additionally, the CD56-expressing T cells are recognized as a NK-like T cell population, they were also discussed during these processes.

Myd88 knockdown with RNA interference induces in vitro immune hyporesponsiveness in dendritic cells from rhesus monkeys

Immature dendritic cells (imDCs) are activated and mature to initiate an adaptive immune response, resulting in allograft rejection and transplantation failure. Myeloid differentiation factor 88 (Myd88) is a key factor in the Toll-like receptor (TLR) signaling pathway. Here, we investigated the effect of Myd88 silencing on DC function and immune response. CD34 + cells were isolated from the bone marrow of rhesus monkeys by the immunomagnetic bead method and then infected with an adenovirus expressing Myd88-specific short hairpin RNA (sh-Myd88). sh-NC (nontargeting negative control)- or sh-Myd88-infected DCs were treated with lipopolysaccharide (LPS) for another 48 h to induce DCS maturation. The maturation of DCs was identified by immunofluorescence staining for MHCII, CD80, and CD86. DC apoptosis was examined using Annexin V/PI staining. DC-related cytokine levels (IFN-γ and IL-12) were assessed by ELISA. A mixed lymphocyte reaction (MLR) was performed to test the effect of Myd88-silenced DCs on T lymphocytes in vitro. The results showed that compared with control or sh-NC-infected DCs, Myd88-silenced DCs had lower MHCII, CD80, CD86, and DC-related cytokine (IFN-γ and IL-12) levels. Myd88 did not affect the apoptosis of DCs. MLR demonstrated that Myd88 silencing could effectively block LPS-activated T cell proliferation in vitro. These data were consistent with the characteristics of tolerogenic DCs. In conclusion, our data indicated that Myd88 silencing could inhibit the maturation of imDCs and alleviate immune rejection, which provides a reference for immune tolerance in clinical liver transplantation.

Gastrodin Ameliorates Acute Rejection via IRE1α/TRAF2/NF-κB in Rats Receiving Liver Allografts

Background

Liver transplantation (LT) is currently an effective treatment for end-stage liver disease, but the occurrence of acute rejection (AR) is still the main problem to be solved. The present study aimed to evaluate the effect of gastrodin (GAS) on LT.

Methods

Rat transplant models were established and divided into SHAM, LT, GAS-L (50 mg/kg GAS), and GAS-H (100 mg/kg GAS) groups. The liver function, inflammatory factors, liver histopathology, survival of rats, number of M2-type macrophages, liver cell apoptosis, and pathway proteins were assayed at 7 days and 14 days after the operations.

Results

With increasing GAS concentrations, liver function, expression of proinflammatory factors in the liver, and expression of M2-type molecules in macrophages were significantly improved, and the survival time of rats was significantly prolonged (P < 0.05). All rats treated with low or high doses of GAS were judged to have nondeterministic acute rejection. Flow cytometry showed that liver cell apoptosis was decreased significantly in the GAS-L and GAS-H groups after GAS administration compared with apoptosis and differentiation in the LT group (P < 0.05). Expression levels of Caspase-3, Bad, and Bax proteins were decreased, and the expression of the antiapoptotic protein Bcl-2 was increased in the GAS-L and GAS-H groups (P < 0.05). Mechanistically, the ERS-related IRE1α/TRAF2/NF-κB pathway was suppressed by GAS, and GAS acted mainly on intrahepatic macrophages to affect AR and reduce ROS production (P < 0.05).

Conclusion

GAS ameliorated AR by inhibiting the IRE1α/TRAF2/NF-κB pathway in LT.

[Effects of Panax notoginseng saponins on liver graft rejection in rats and the mechanisms]

OBJECTIVE

To investigate the effects of Panax notoginseng saponins (PNS) on the functional status of Kupffer cells (KCs) and immune environment after liver transplantation and explore the possible mechanisms.

METHODS

KCs were isolated from rats and assessed for phagocytic activity and viability using ink and Trypan blue staining. The cells were exposed to lipopolysaccharide (LPS) alone or in combination with PNS treatment at 0, 10 or 20 μmol/L. The expressions of the inflammatory factors and the oxidative stress products in the cells and the supernatant were assayed with Western blotting and ELISA; the expression of CD206 was detected using immunofluorescence assay, and the expressions of NF-κB and Keap1-Nrf2-ARE pathway proteins were detected using Western blotting. We established an orthotopic liver transplantation (LT) model in rats and assessed the effect of 200 mg/kg PNS on the graft function, inflammatory factors, pathology of the liver tissue, hepatocyte apoptosis and survival time of the rats in comparison with those in rats receiving a sham operation or PBS treatment following LT.

RESULTS

Treatment with PNS significantly lowered the levels of inflammatory factors and oxidative stress products and increased the levels of interleukin-10 (IL-10) and SOD in a concentration-dependent manner in the KCs (P < 0.05). Immunofluorescence assay showed that PNS treatment obviously increased the expression of CD206 in the KCs. PNS treatment also significantly reduced the expressions of IRAK4, p-IKKα, p-IκBα, p-p65 and Keap1 proteins and increased the expression levels of Nrf2 and ARE proteins in the KCs (P < 0.05). In the rat models of LT, PNS treatment significantly improved the liver graft function, lowered the expression of the pro-inflammatory factors, and reduced hepatocyte apoptosis as compared with PBS treatment. PNS treatment obviously alleviated pathological changes in the liver graft and significantly prolonged the survival time of the rats following LT (P < 0.05). In addition, injection of GdCl3 to block KC function resulted in severe acute graft rejection in the rats regardless of PNS treatment (P > 0.05).

CONCLUSIONS

PNS can reduce inflammatory response and oxidative stress in activated KCs by inhibiting NF-κB and Keap1-Nrf2-ARE pathways and promote the polarization of KCs into M2 phenotype to prolong the survival time of rats after LT.

Heme oxygenase-1-transduced bone marrow mesenchymal stem cells in reducing acute rejection and improving small bowel transplantation outcomes in rats

Background

We determined whether bone marrow mesenchymal stem cells (BMMSCs) transduced with heme oxygenase-1 (HO-1), a cytoprotective and immune-protective factor, could improve outcomes for small bowel transplantation (SBTx) in rats.

Methods

We performed heterotopic SBTx from Brown Norway rats to Lewis rats, before infusing Ad/HO-1-transduced BMMSCs (Ad/HO-1/BMMSCs) through the superficial dorsal veins of the penis. Respective infusions with Ad/BMMSCs, BMMSCs, and normal saline served as controls. The animals were sacrificed after 1, 5, 7, or 10 days. At each time point, we measured small bowel histology and apoptosis, HO-1 protein and mRNA expression, natural killer (NK) cell activity, cytokine concentrations in serum and intestinal graft, and levels of regulatory T (Treg) cells.

Results

The saline-treated control group showed aggravated acute cellular rejection over time, with mucosal destruction, increased apoptosis, NK cell activation, and upregulation of proinflammatory and immune-related mediators. Both the Ad/BMMSC-treated group and the BMMSC-treated group exhibited attenuated acute cellular rejection at an early stage, but the effects receded 7 days after transplantation. Strikingly, the Ad/HO-1/BMMSC-treated group demonstrated significantly attenuated acute cellular rejection, reduced apoptosis and NK cell activity, and suppressed concentrations of inflammation and immune-related cytokines, and upregulated expression of anti-inflammatory cytokine mediators and increased Treg cell levels.

Conclusion

Our data suggest that Ad/HO-1-transduced BMMSCs have a reinforced effect on reducing acute rejection and protecting the outcome of SBTx in rats.

Mesenchymal stem cells improve the outcomes of liver recipients via regulating CD4+ T helper cytokines in rats

BACKGROUND

Bone marrow mesenchymal stem cells (BMMSCs) exert immunosuppressive activities in transplantation. This study aimed to determine whether BMMSCs reduce acute rejection and improve outcomes of liver transplantation in rats.

METHODS

Orthotopic liver transplantation from Lewis to Brown Norway rats was performed, which was followed by the infusion of BMMSCs through the penile superficial dorsal vein. Normal saline infusion was used as a control. Animals were sacrificed at 0, 24, 72, or 168 hours after BMMSCs infusion. Liver grafts, and recipient serum and spleen tissues were obtained. Histopathology, apoptosis, serum liver enzymes, serum cytokines, and circulating regulatory T (Treg), Th1, Th2 and Th17 cells were assessed at each time point.

RESULTS

BMMSCs significantly attenuated acute rejection and improved the survival rate of allogeneic liver transplantation recipients. Liver enzymes and liver apoptosis were significantly alleviated. The levels of the Th1/Th2 ratio-associated cytokines such as IL-2 and IFN-gamma were significantly reduced and IL-10 was significantly increased. The levels of the Th17/Tregs axis-associated cytokines such as IL-6, IL-17, IL-23, and TNF-alpha were significantly reduced, whereas TGF-beta concentration was significantly increased. Moreover, flow cytometry analysis showed that the infusion of BMMSCs significantly increased Th2 and Treg cells and decreased Th1 and Th17 cells.

CONCLUSION

BMMSCs had immunomodulatory effects, attenuated acute rejection and improved outcomes of allogeneic liver transplantation in rats by regulating the levels of cytokines associated with Th1/Th2 and Th17/Treg ratios.

Immunologic Predictors of Liver Transplantation Outcomes in HIV-HCV Co-Infected Persons

Liver disease is a leading cause of mortality among HIV-infected persons in the highly active anti-retroviral therapy (HAART) era. Hepatitis C Virus (HCV) co-infection is prevalent in, and worsened by HIV; consequently many co-infected persons require liver transplantation (LT). Despite the need, post-LT outcomes are poor in co-infection. We examined predictors of outcomes post-LT. Immunologic biomarkers of immune activation, microbial translocation, and Th1/Th2 skewing were measured pre-LT in participants enrolled in a cohort of HIV infected persons requiring solid organ transplant (HIVTR). Predictive biomarkers were analyzed in Cox-proportional hazards models; multivariate models included known predictors of outcome and biomarkers from univariate analyses. Sixty-nine HIV-HCV co-infected persons with available pre-LT samples were tested: median (IQR) CD4+ T-cell count was 286 (210–429) cells mm^-3; 6 (9%) had detectable HIV RNA. Median (IQR) follow-up was 2.1 (0.7–4.0) years, 29 (42%) people died, 35 (51%) had graft loss, 22 (32%) were treated for acute rejection, and 14 (20%) had severe recurrent HCV. In multivariate models, sCD14 levels were significantly lower in persons with graft loss post-LT (HR 0.10 [95%CI 0.02–0.68]). IL-10 levels were higher in persons with rejection (HR 2.10 [95%CI 1.01–4.34]). No markers predicted severe recurrent HCV. Monocyte activation pre-LT may be mechanistically linked to graft health in HIV-HCV co-infection.

Immune monitoring of immunosuppression withdrawal of liver transplant recipients

Several studies have shown that some liver transplant recipients may tolerate immunosuppression withdrawal. Mechanisms and biomarkers of tolerance are not well known.

METHODS

Twenty-four LT patients with immunosuppression side-effects underwent progressive immunosuppression withdrawal. Peripheral lymphocyte populations and secretion of cytokines were analyzed at baseline and during withdrawal until tolerance (n = 15) or rejection (n = 9), as well as 3 months after tolerance achievement or rejection resolution (as follow-up). Immunological markers were compared among groups.

RESULTS

The percentages of CD3+CD4+ cells progressively decreased in both groups. CD3+CD8+ cells gradually increased in tolerant patients. B lymphocytes gradually decreased in tolerant and initially in non-tolerant patients, reverting at rejection. Regulatory T cells progressively increased until rejection in non-tolerants, decreasing to basal levels after renewing immunosuppression; no significant changes were found in tolerant patients. The percentages and absolute counts of natural killer cells significantly increased in both groups, being more evident in tolerant patients. The secretion of several cytokines was higher in non-tolerant patients when rejection was diagnosed.

CONCLUSIONS

The greater increase of natural killer cells in tolerant patients suggests their potential role in the tolerance phenomenon.

Kupffer cells and liver transplantation

Nowadays, liver transplantation is globally considered the most effective treatment for end-stage liver diseases. Ischemia-reperfusion (I/R) injury and immune rejection response (IRR) are the two major imperfections which severely affect the recipients' prognosis and survival rate without satisfactory clinical management strategies. Therefore, exploring effective methods to improve I/R injury and IRR have important clinical significance under circumstances of shortage of donor livers. Kupffer cells (KCs) are the largest population of antigen representing cells (APCs) which settle in the liver. As the first defensive line of the live, KCs exhibit various biological effects. However, the exact mechanisms responsible for the role of KCs in I/R injury and IRR remain elusive. We hereby review the current finding about the role of KCs in I/R injury and IRR.

Preconditioning donor livers with cromolyn or compound 48/80 prolongs recipient survival in a rat orthotopic liver transplantation model

BACKGROUND

Acute rejection (AR) remains a challenge in organ transplantation. Preconditioning donor organs can reduce AR and prolong survival. Whether preconditioning with cromolyn (CRM), a mast cell (MC) stabilizer, or compound 48/80 (CMP 48/80), a MC degranulator, can alleviate AR and prolong survival has not been studied.

METHODS

We used the male-DA-to-female-Lewis-rat orthotopic liver transplantation (OLT) model. Donors were preconditioned with CRM in a MC stabilizing way (CRM group) or CMP 48/80 in a MC depleting way (CMP 48/80 group). Rats preconditioned with phosphate-buffered saline were used as controls (PBS group). After preconditioning, OLT surgeries were carried out. OLT male-Lewis-to-female-Lewis-rats were used as the syngeneic group (syngeneic group).

RESULTS

Rats in the PBS group developed AR rapidly and died at 7.40 ± 1.14 days. Rats in the CRM and CMP 48/80 groups had significantly slower rejections and died at day 17.40 ± 1.67 or 14.20 ± 2.28, respectively (P < .05). Rats in the syngeneic group survived more than 60 days. Rejection activity indexes (RAIs) and liver functions were all alleviated through CRM or CMP 48/80 preconditioning. Interferon-γ messenger RNA (mRNA) expressions were reduced and interleukin-10 mRNA levels were higher in allografts in the CRM and CMP 48/80 groups, compared with the PBS group. These were confirmed by testing serum interferon-γ and interlerkin-10.

CONCLUSION

Preconditioning donor livers with CRM or CMP 48/80 can reduce AR and prolong survival of recipients after OLT.

Gadolinium chloride suppresses acute rejection and induces tolerance following rat liver transplantation by inhibiting Kupffer-cell activation

The aim of the present study was to investigate the mechanism by which gadolinium chloride (GdCl₃) inhibits Kupffer cell (KC) activation and its ability to suppress acute rejection and induce tolerance following liver transplantation in rats. Rats were randomly divided into control, liver transplantation with GdCl₃ pretreatment and liver transplantation with normal saline pretreatment groups. The survival rate, liver function, hepatic pathological histology, cytokine levels in the liver and bile, activity of nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) in KCs, and expression levels of membranous molecules on the KCs were observed. It was identified that the one-month survival rate in the GdCl₃ group was significantly higher compared with that in the saline group (P<0.05). The liver function in the GdCl₃ group gradually recovered following transplantation surgery; however, it progressively deteriorated in the saline group. There were minor changes of hepatic pathological histology in the GdCl₃ group, whereas changes typical of acute rejection occurred in the saline group. In the GdCl₃ group, the levels of interferon γ and interleukin (IL)-2 were significantly lower whereas the levels of IL-10 were significantly higher compared with those in the control and saline groups (all P<0.01). The IL-4 levels in the GdCl₃ and control groups were similar. The activity of NF-κB in the saline group was significantly higher compared with those in the control and GdCl₃ groups (P<0.01). The expression levels of major histocompatibility complex-II, cluster of differentiation (CD)80 and CD86 on the KC membranes in the GdCl₃ group was significantly lower compared with those in the control group (P<0.05); however, these membranous proteins were highly expressed in the saline group. These data indicate that GdCl₃ efficiently inhibits the immunological activity of KCs, suppresses acute rejection and induces tolerance following liver allograft transplantation in rats.

Knockdown of microRNA-155 in Kupffer cells results in immunosuppressive effects and prolongs survival of mouse liver allografts

BACKGROUND

Our previous studies have shown that Kupffer cells (KCs) play a crucial role in postoperative pathologic changes. Recent reports have demonstrated that microRNA-155 (miR-155) is associated with inflammation and upregulation of proinflammatory mediators in the peripheral blood and allografts of transplant patients. However, the precise mechanism for this remains unknown.

METHODS

KCs isolated from BALB/c mice were transfected with miR-155 mimic or inhibitor. Levels of suppressor of cytokine signaling 1/Janus kinase/signal transducer and activator of transcription (SOCS1/JAK/STAT) proteins and surface molecules (MHC-II, CD40, and CD86) were then measured. T-cell proliferation and apoptosis were evaluated in mixed lymphocyte reactions. Orthotopic liver transplantation was performed in mice after miR-155 short hairpin RNA lentivirus treatment, and postoperative survival, liver function and histology, and mRNA and protein expression were analyzed.

RESULTS

miR-155 knockdown in KCs decreased MHC-II, CD40, and CD86 expression, suppressed antigen-presenting function, and affected SOCS1/JAK/STAT inflammatory pathways. In addition, KCs transfected with miR-155 inhibitor and cocultured with T lymphocytes showed reduced T-cell responses but a greater number of apoptotic T cells. Finally, miR-155 suppression in graft liver prolonged liver allograft survival and improved liver function. The changes were closely associated with the levels of T helper 1 and 2 (Th1/Th2) cytokines and T-cell apoptosis, but a direct mechanistic link in vivo was not established.

CONCLUSION

These data suggest miR-155 regulates the balance of Th1/Th2 cytokines and the maturation and function of KCs in mice. miR-155 repression in KCs positively regulates KC function toward immunosuppression and prolongs liver allograft survival.

Multi-scale optical imaging of the delayed type hypersensitivity reaction attenuated by rapamycin

Neutrophils and monocytes/macrophages (MMs) play important roles in the development of cell-mediated delayed type hypersensitivity (DTH). However, the dynamics of neutrophils and MMs during the DTH reaction and how the immunosuppressant rapamycin modulates their behavior in vivo are rarely reported. Here, we take advantage of multi-scale optical imaging techniques and a footpad DTH reaction model to non-invasively investigate the dynamic behavior and properties of immune cells from the whole field of the footpad to the cellular level. During the classic elicitation phase of the DTH reaction, both neutrophils and MMs obviously accumulated at inflammatory foci at 24 h post-challenge. Rapamycin treatment resulted in advanced neutrophil recruitment and vascular hyperpermeability at an early stage (4 h), the reduced accumulation of neutrophils (> 50% inhibition ratio) at 48 h, and the delayed involvement of MMs in inflammatory foci. The motility parameters of immune cells in the rapamycin-treated reaction at 4 h post-challenge displayed similar mean velocities, arrest durations, mean displacements, and confinements as the classic DTH reaction at 24 h. These results indicate that rapamycin treatment shortened the initial preparation stage of the DTH reaction and attenuated its intensity, which may be due to the involvement of T helper type 2 cells or regulatory T cells.

Protective role of Shenfu on ischemia-reperfusion injury of rat liver grafts

AIMS

We sought to investigate the protective role of Shenfu (SF),a traditional Chinese formulation comprising Radix Ginseng and Radix Aconitum Carmichaeli on ischemia-reperfusion injury in rat liver grafts.

METHODS

Ninety-six male Sprague Dawley rats were used as donors (n = 48) and recipients (n = 48) of orthotopic liver transplantation. They were randomly divided into a control group with donor livers injected with saline through the portal vein immediately after recovery versus the SF group, with livers injected with SF. Each group was further divided into 3 subgroups equally to obtain bood and hepatic tissues samples at 2, 4, and 6 hours reperfusion.

RESULTS

At each phase, the SF group, showed significantly higher bile production (P < .05) with lower serum levels of alanine aminotransferase and tumor necrosis factor-α, and nuclear factor-κB expression in the hepatic tissues. (P < .05). SF group hepatic tissues showed less injury compared with controls.

CONCLUSION

SF injection seemed to protect hepatocytes from injury during the early reperfusion phase and to improve subsequent rat liver graft function.

The role of invariant NKT cells in liver transplant tolerance in rats

OBJECTIVE

The aim of this study was to investigate the role of invariant natural killer T (iNKT) cells in liver transplant tolerance in rats.

METHODS

Animals were randomly divided into 3 groups. The α-galactosylceramide (α-GalCer) group underwent injection through the caudal vein; the saline group received the same dose of saline and the control group received no treatment. Ten rats in each group were examined for survival the others were humanely killed on the seventh day posttransplantation. Liver tissues were used to assess histopathologic changes. Real-time polymerase chain reaction (PCR) was performed to determine the relative expressions of messanger RNAs of Th1/Th2-related cytokine (mRNAs) in the liver allograft. The serum levels of related cytokines were determined using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Allograft survival was significantly higher among the α-galactosylceramide α-GalCer group than the saline or control groups. The histopathology showed mild changes in the α-galactosylceramide α-GalCer compared with the other 2 groups. Real-time PCR showed the relative expression of Th1-related cytokine interferen (IFN)-γ mRNA to be significantly lower in the α-galactosylceramide α-GalCer compared with the other 2 groups, while the Th2-related cytokine interleukin (IL)-10 mRNA was much higher. The ELISA results confirmed these differential expressions.

CONCLUSION

The iNKT cells may play a pivotal role in liver transplant tolerance due to their regulatory functions on the Th1/Th2 imbalance. iNKT cells should be considered to be significant targets because of their attractive specificity and induction of liver allograft tolerance.

A crucial role of IL-17 and IFN-γ during acute rejection of peripheral nerve xenotransplantation in mice

Nerve injuries causing segmental loss require nerve grafting. However, autografts and allografts have limitations for clinical use. Peripheral nerve xenotransplantation has become an area of great interest in clinical surgery research as an alternative graft strategy. However, xenotransplant rejection is severe with cellular immunity, and Th1 cells play an important role in the process. To better understand the process of rejection, we used peripheral nerve xenografts from rats to mice and found that mononuclear cells expressing IFN-γ and IL-17 infiltrated around the grafts, and IFN-γ and IL-17 producing CD4+ and CD8+ T cells increased during the process of acute rejection. The changes of IL-4 level had no significant difference between xenotransplanted group and sham control group. The rejection of xenograft was significantly prevented after the treatment of IL-17 and IFN-γ neutralizing antibodies. These data suggest that Th17 cells contribute to the acute rejection process of peripheral nerve xenotransplant in addition to Th1 cells.

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.

Mechanism of immune hyporesponsiveness induced by recipient- derived immature dendritic cells in liver transplantation rat

OBJECTIVE

To investigate the mechanism of immune hyporesponsiveness induced by donor-antigen- unloaded recipient-derived immature dendritic cell (imDC) of liver grafts in rats.

METHODS

Forty Sprague-Dawley rats (donor) and forty male Wistar rats (recipient) were randomly divided into 4 groups: control, cyclosporine A (CsA), mature DC (mDC), and imDC groups respectively, with 10 donor rats and 10 recipient rats in each group. Recipient rats in CsA group were treated with 10 mg•kg⁻¹•d⁻¹ CsA starting day 2 after the transplantation. Recipients in the mDC or imDC groups were given Wistar rat derived mDCs (1 × 10⁶/rat) or imDCs (1 × 10⁶/rat) via dorsal vein of the penis respectively 1 day before the transplantation. In each group, 5 recipients were kept for determination of survival time and the other 5 rats were executed at day 10 after transplantation. Blood samples were collected for the measurement of serum alanine aminotransferase (ALT), total bilirubin (TBIL), interleukin 2 (IL-2), interferon gamma (IFN-γ), IL-4, and IL-10 levels. Liver tissue was harvested for HE staining and acute rejection evaluation. Expression levels of Fas-L/Fas in the grafts were detected by immunohistochemical staining; and Western blot was used to detect the expression level of Scurfin.

RESULTS

The survival time of CsA and imDC groups was significantly longer than that of control and mDC groups (all P < 0.05). The levels of serum ALT and TBIL in the control group (2072.20 ± 217.93 IU/L and 147.42 ± 22.02 µmol/L) and mDC group (2117.00 ± 285.13 IU/L and 141.58 ± 20.82 µmol/L) were significantly higher than those in the CsA group (59.68 ± 13.48 IU/L and 15.40 ± 2.13 µmol/L) or imDC group (50.80 ± 9.63 IU/L and 14.44 ± 3.49 µmol/L) (all P < 0.05). In the CsA and imDC groups, the levels of IL-2 (22.52 ± 3.75 pg/mL and 22.12 ± 3.90 pg/mL) and IFN-γ (309.20 ± 25.19 pg/mL and 321.00 ± 21.64 pg/mL) were significantly lower, but the levels of IL-4 (297.60 ± 25.07 pg/mL and 277.00 ± 22.47 pg/mL) and IL-10 (1226.00 ± 140.49 pg/mL and 1423.00 ± 106.39 pg/mL) were higher than those of the control (IL-2: 147.78 ± 12.80 pg/mL, IFN-γ: 1758.60 ± 106.22 pg/mL, IL-4: 17.40 ± 4.77 pg/mL, IL-10: 81.00 ± 9.47 pg/mL) and mDC groups (IL-2: 142.34 ± 9.29 pg/mL, IFN-γ: 1835.00 ± 82.63 pg/mL, IL-4: 15.60 ± 3.96 pg/mL, IL-10: 68.80 ± 11.23 pg/mL) (all P < 0.01). The expression level of Scurfin protein on CD4+ CD25+ T cells of the imDC group (1.34 ± 0.29) was significantly higher than that in the control (0.72 ± 0.13), CsA (0.37 ± 0.11), and mDC groups (0.78 ± 0.17) (all P < 0.05).

CONCLUSION

Donor-antigen-unloaded recipient-derived imDC is an effective treatment in inducing immune hyporesponsiveness through induction of T cell apoptosis, shift in Thl/Th2 balance, and proliferation of regulatory T cell.

The dynamic changes of Th17/Treg cytokines in rat liver transplant rejection and tolerance

Acute rejection is still a major cause of early graft loss and a risk factor for long-term recipient post-transplant survival. Recently, CD4(+) CD25(+) Foxp3(+) regulatory T (Treg) cells and Th17 cells have been described as two distinct subsets with opposing effects on autoimmunity and transplant immunity. We investigated the existence of Th17/Treg functional imbalance between tolerance and rejection groups during rat liver transplantation. Then, Th17/Treg functions on different levels were investigated comparatively between those two groups, including related cytokine secretion and key transcription factors. REJ groups revealed significant increase in Th17-related cytokine (IL-17, IL-6 and IL-23) and transcription factor (RORγt) levels and remarkable decrease in Treg-related cytokine (IL-10 and TGF-β1) and transcription factor (Foxp3) levels when compared to day-matched TOL groups from day 3 post-transplantation. Results indicated Th17/Treg functional imbalance between tolerance and rejection groups during rat liver transplantation, suggesting a potential role of Th17/Treg imbalance in pathogenesis of acute transplant rejection.

Emodin prolongs recipient survival time after orthotopic liver transplantation in rats by polarizing the Th1/Th2 paradigm to Th2

Advances in immunosuppressive drugs have improved the short-term survival of liver transplantation. However, drug toxicities have been a serious problem in patients after long-term administration. Therefore, it is necessary to develop a novel immunosuppressant with low-toxicity. We investigated the immunosuppressive effects of Emodin on acute graft rejection following liver transplantation in rats. The recipient rats of orthotopic liver transplantation were divided into groups as follows: isograft+NS group, allograft+NS group, and allograft+emodin group. The survival time of the recipients in each group was recorded. Histopathological changes in the liver, as well as serum concentrations of IL-2, TNF-α, and IL-10 and their expressions in liver tissue were determined. Our results showed that Emodin treatment prolonged liver allograft survival time and inhibited histopathologic changes of acute graft rejection. The rejection activity index in groups isograft+NS, allograft+NS, and allograft+emodin were 1.52 ± 0.37, 6.95 ± 0.75, and 4.23 ± 0.51, respectively (P < 0.01, isograft+NS group vs. allograft+emodin group and allograft+NS group vs. allograft+emodin group). The serum levels of IL-2 and TNF-α were down-regulated but that of IL-10 was up-regulated by Emodin. Serum levels of IL-2 and TNF-α were higher in allograft+NS group than the allograft+emodin group, but that of IL-10 showed opposite effects (P < 0.05 or 0.01). Changes in the expression of these cytokines in transplanted liver tissue were consistent with changes in serum concentrations. These results demonstrate that Emodin has therapeutic potentials for alleviating acute rejection following liver transplantation in rats and prolonging liver allograft survival. The mechanisms underlying this effect may be associated with polarizing the Th1/Th2 paradigm to Th2.

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.

Effect of emodin in suppressing acute rejection following liver allograft transplantation in rats

OBJECTIVE

To investigate the mechanism of action of emodin for suppressing acute allograft rejection in a rat model of liver transplantation.

METHODS

Brown Norway (BW) recipient rats of orthotopic liver transplantation (OLT) were divided into three groups, Group A receiving isografting (with BW rats as donor), Group B receiving allografting (with Lewis rats as donor), Group C receiving allografting and emodin treatment (50 mg/kg daily). They were sacrificed on day 7 of post-transplantation, and their hepatic histology, plasma cytokine levels, and T-cell subset expression were detected.

RESULTS

Compared with those in Group A, rats: in Group B exhibited severe allograft rejection with a rejection activity index (RAI) of 7.67+/-0.98, extensive hepatocellular apoptosis with an apoptosis index (AI) of 35.83+/-2.32, and elevated plasma levels of interleukin-2 (IL-2), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha), CD4(+) and CD4 CD4(+)/CD8(+) ratio. However, recipients in Group C showed a decrease in histological grade of rejection and hepatocellular apoptosis, as well as a decrease in plasma levels of IL-2, TNF-alpha, CD4(+) and CD4(+)/CD8(+) ratio, but elevated levels of IL-10 as compared with the allograft group.

CONCLUSION

Post-OLT acute rejection could be attenuated by emodin, its mechanism of action may be associated with protecting hepatocytes from apoptosis, polarizing the Th 1 paradigm to Th2, and inhibiting the proliferation of CD4(+) T cell in plasma.

Induction of allogeneic mixed chimerism by immature dendritic cells and bone marrow transplantation leads to prolonged tolerance to major histocompatibility complex disparate allografts

Mixed chimerism has been shown to lead to prolonged major histocompatibility complex (MHC) disparate allograft survival and immune-specific tolerance; however, traditional conditioning regimes often involve myeloablation, which may pose a significant safety risk. In this study we examined the use of donor C57BL/6 (H-2(b)) immature dendritic cells (imDCs) to tolerize the BALB/c (H-2(d)) recipient to bone marrow transplantation (BMT), allowing the induction of mixed chimerism without immunosuppression or myeloablation. We showed that successful mismatched bone marrow engraftment can be achieved using imDCs given up to 3 days prior to BMT and that mixed chimerism can be established and detected in excess of 100 days post-BMT without evidence of graft-versus-host disease. Furthermore, we showed that imDCs can suppress lymphocyte proliferation in response to mismatched MHC stimulation, leading to increased expression of interleukin (IL)-4 and IL-10 and decreased expression of IL-2 and interferon-gamma (IFN-gamma). The induction of stable chimeras through pre-conditioning of mice with donor imDCs followed by BMT led to tolerance, allowing the long-term survival (> 110 days) of mismatched cardiac allografts and the prolonged survival of mismatched skin allografts without the need for immunosuppression or myeloablation. Transplantation with third-party C3H allografts were rapidly rejected in this model, suggesting that immune-specific tolerance was achieved. The induction of immune-specific tolerance without the need for immunosuppression or myeloablation represents a significant advance in transplant immunology and may provide clinicians with a plausible alternative in combating organ rejection following transplantation.