Acute Liver Allograft Rejection Research Articles

Computational identification of novel potential genetic pathogenesis and otherwise biomarkers in acute liver allograft rejection

Acute cellular rejection (ACR) is a prevalent postoperative complication following liver transplantation (LT), exhibiting an increasing incidence of morbidity and mortality. However, the molecular mechanisms of ACR following LT remain unclear. To explore the genetic pathogenesis and identify biomarkers of ACR following LT, three relevant Gene Expression Omnibus (GEO) datasets consisting of data on ACR or non-ACR patients after LT were comprehensively investigated by computational analysis. A total of 349 upregulated and 260 downregulated differentially expressed genes (DEGs) and eight hub genes (ISG15, HELZ2, HNRNPK, TIAL1, SKIV2L2, PABPC1, SIRT1, and PPARA) were identified. Notably, HNRNPK, TIAL1, and PABPC1 exhibited the highest predictive potential for ACR with AUCs of 0.706, 0.798, and 0.801, respectively. KEGG analysis of hub genes revealed that ACR following LT was predominately associated with ferroptosis, protein processing in the endoplasmic reticulum, complement and coagulation pathways, and RIG-I/NOD/Toll-like receptor signaling pathway. According to the immune cell infiltration analysis, γδT cells, NK cells, Tregs, and M1/M2-like macrophages had the highest levels of infiltration. Compared to SIRT1, ISG15 was positively correlated with γδT cells and M1-like macrophages but negatively correlated with NK cells, CD4+ memory T cells, and Tregs. In conclusion, this study identified eight hub genes and their potential pathways, as well as the immune cells involved in ACR following LT with the greatest levels of infiltration. These findings provide a new direction for future research on the underlying mechanism of ACR following LT.

Luteolin attenuates acute liver allograft rejection in rats by inhibiting T cell proliferation and regulating T cell subsets.

Allograft rejection continues to be a significant cause of morbidity and graft failure for liver transplant recipients. Existing immunosuppressive regimens have many drawbacks, thus safe and effective long-term immunosuppressive regimens are still required. Luteolin (LUT), a natural component found in many plants, has a variety of biological and pharmacological effects and shows good anti-inflammatory activity in inflammatory and autoimmune diseases. Nevertheless, it remains unclear how it affects acute organ rejection after allogeneic transplantation. In this study, a rat liver transplantation model was constructed to investigate the effect of LUT on acute rejection of organ allografts. We found that LUT significantly protected the structure and function of liver grafts, prolonged recipient rat survival, ameliorated T cell infiltration, and downregulated proinflammatory cytokines. Moreover, LUT inhibited the proliferation of CD4+ T cells and Th cell differentiation but increased the proportion of Tregs, which is the key to its immunosuppressive effect. In vitro, LUT also significantly inhibited CD4+ T cell proliferation and Th1 differentiation. There may be important implications for improving immunosuppressive regimens for organ transplantation as a result of this discovery.

Successful treatment of acute antibody-mediated rejection of liver allograft with imlifidase: A case report

Although the incidence of acute antibody mediated rejection in liver transplantation is low, the consequences of acute antibody mediated rejection can be devastating, often leading to severe fibrotic changes and early graft loss. Conventional treatment modalities for management of moderate-to-severe acute antibody mediated rejection in liver transplant continue to rely on of corticosteroids, plasmapheresis, and intravenous immunoglobulin. However, management of refractory, severe antibody mediated rejection remains without a clear gold-standard approach. This case report describes successful first use of Imlifidase, an Ig-G degrading enzyme, for management of acute refractory antibody mediated rejection following orthotopic liver transplant. This 41-year-old woman developed acute antibody meditated rejection and donor specific antibodies within two weeks of undergoing an A2 to O liver transplant. Following unsuccessful treatment with conventional modalities, treatment with Imlifidase resulted in normalization of liver function, resolution of antibody mediated rejection on surveillance biopsy, and disappearance of donor specific antibodies. Imlifidase could represent a promising treatment for refractory antibody mediated rejection in liver transplantation and warrants further study.

Killer Cell Immunoglobulin-like Receptors (KIR) and Human Leucocyte Antigen C (HLA-C) Increase the Risk of Long-Term Chronic Liver Graft Rejection.

Chronic liver rejection (CR) represents a complex clinical situation because many patients do not respond to increased immunosuppression. Killer cell immunoglobulin-like receptors/Class I Human Leukocyte Antigens (KIR/HLA-I) interactions allow for predicting Natural Killer (NK) cell alloreactivity and influence the acute rejection of liver allograft. However, its meaning in CR liver graft remains controversial. KIR and HLA genotypes were studied in 513 liver transplants using sequence-specific oligonucleotides (PCR-SSO) methods. KIRs, human leucocyte antigen C (HLA-C) genotypes, KIR gene mismatches, and the KIR/HLA-ligand were analyzed and compared in overall transplants with CR (n = 35) and no-chronic rejection (NCR = 478). Activating KIR (aKIR) genes in recipients (rKIR2DS2+ and rKIR2DS3+) increased CR compared with NCR groups (p = 0.013 and p = 0.038). The inhibitory KIR (iKIR) genes in recipients rKIR2DL2+ significantly increased the CR rate compared with their absence (9.1% vs. 3.7%, p = 0.020). KIR2DL3 significantly increases CR (13.1% vs. 5.2%; p = 0.008). There was no influence on NCR. CR was observed in HLA-I mismatches (MM). The absence of donor (d) HLA-C2 ligand (dC2−) ligand increases CR concerning their presence (13.1% vs. 5.6%; p = 0.018). A significant increase of CR was observed in rKIR2DL3+/dC1− (p = 0.015), rKIR2DS4/dC1− (p = 0.014) and rKIR2DL3+/rKIR2DS4+/dC1− (p = 0.006). Long-term patient survival was significantly lower in rKIR2DS1+rKIR2DS4+/dC1− at 5–10 years post-transplant. This study shows the influence of rKIR/dHLA-C combinations and aKIR gene-gene mismatches in increasing CR and KIR2DS1+/C1-ligands and the influence of KIR2DS4+/C1-ligands in long-term graft survival.

Renal clearable polyfluorophore nanosensors for early diagnosis of cancer and allograft rejection.

Optical nanoparticles are promising diagnostic tools; however, their shallow optical imaging depth and slow clearance from the body have impeded their use for in vivo disease detection. To address these limitations, we develop activatable polyfluorophore nanosensors with biomarker-triggered nanoparticle-to-molecule pharmacokinetic conversion and near-infrared fluorogenic turn-on response. Activatable polyfluorophore nanosensors can accumulate at the disease site and react with disease-associated proteases to undergo in situ enzyme-catalysed depolymerization. This disease-specific interaction liberates renal-clearable fluorogenic fragments from activatable polyfluorophore nanosensors for non-invasive longitudinal urinalysis and outperforms the gold standard blood and urine assays, providing a level of sensitivity and specificity comparable to those of invasive biopsy and flow cytometry analysis. In rodent models, activatable polyfluorophore nanosensors enable ultrasensitive detection of tumours (1.6 mm diameter) and early diagnosis of acute liver allograft rejection. We anticipate that our modular nanosensor platform may be applied for early diagnosis of a range of diseases via a simple urine test.

High Mobility Group Box 1 Contributes to the Acute Rejection of Liver Allografts by Activating Dendritic Cells.

Acute rejection induced by the recognition of donor alloantigens by recipient T cells leads to graft failure in liver transplant recipients. The role of high mobility group box 1 (HMGB1), an inflammatory mediator, in the acute allograft rejection of liver transplants is unknown. Here, rat orthotopic liver transplantation was successfully established to analyze the expression pattern of HMGB1 in liver allografts and its potential role in promoting the maturation of dendritic cells (DCs) to promote T cell proliferation and differentiation. Five and 10 days after transplantation, allografts showed a marked upregulation of HMGB1 expression accompanied by elevated levels of serum transaminase and CD3+ and CD86+ inflammatory cell infiltration. Furthermore, in vitro experiments showed HMGB1 increased the expressions of co-stimulatory molecules (CD80, CD83, and MHC class II) on bone marrow-derived DCs. HMGB1-pulsed DCs induced naive CD4+ T cells to differentiate to Th1 and Th17 subsets secreting IFN-γ and IL-17, respectively. Further in vivo experiments confirmed the administration of glycyrrhizic acid, a natural HMGB1 inhibitor, during donor liver preservation had therapeutic effects by reducing inflammation and hepatocyte damage reflected by a decline in serum transaminase and prolonged allograft survival time. These results suggest the involvement of HMBG1 in acute liver allograft rejection and that it might be a candidate therapeutic target to avoid acute rejection after liver transplantation.

Hepatocellular carcinoma recurrence after acute liver allograft rejection treatment: A multicenter European experience

BackgroundDuring the last decades, several risk factors for the recurrence of hepatocellular carcinoma (HCC) after liver transplantation (LT) have been investigated. However, the impact of two important drivers of oncogenesis, namely the immunosuppression and the treatment of acute cellular rejection (ACR) have been marginally addressed. This study aimed at investigating the impact of ACR treatment on the incidence of tumor recurrence in a large European HCC-LT population. MethodsSeven hundred and eighty-one adult patients transplanted between February 1, 1985 and June 30, 2016 were retrospectively analyzed. After propensity score match, 116 patients treated for ACR using steroid boluses were compared with 115 patients who did not present any ACR or a histologic but clinical irrelevant ACR. ResultsSteroid boluses treated patients had a 18-fold higher overall incidence of HCC recurrence than those non-treated patients (16.4% vs. 0.9%; P<0.0001). At multivariate Cox regression analysis, steroid boluses used to treat ACR were an independent risk factor for HCC recurrence (HR=14.2; 95% CI: 1.8–110.4; P = 0.010). ConclusionsThe decision to treat ACR as well as to reinforce immunosuppression load should be cautiously taken in view of the presented results. Prospective studies are needed to further elucidate the clinical impact of immunosuppression on HCC recurrence after transplantation.

A risk assessment model of acute liver allograft rejection by genetic polymorphism of CD276.

BackgroundLiver transplantation is an effective therapy for end‐stage liver diseases and acute liver failure. After the operation, however, recipients may suffer grafts loss induced by alloimmune reaction, which is termed as acute allograft rejection. The interaction between costimulatory molecules, CD276, and its ligand, TREML2, promotes T cell‐mediated immune response, as well as acute or chronic allograft rejection. Our research aimed at correlating genetic polymorphisms of CD276/TREML2 with acute rejection, and evaluating its prognostic value of acute rejection after liver transplantation.MethodsThe study enrolled a total of 388 recipients. Among them, acute allograft rejection was observed in 54 cases. We performed single nucleotide polymorphism genotyping of CD276, including rs11072431, rs11574495, rs12593558, rs12594627, rs2127015, rs3816661 and rs7176654, and TREML2, including rs4714431, rs6915083, rs7754593, and rs9394767 from preoperative peripheral blood genome DNA.ResultsWe found rs2127015 of CD276, rs6915083 and rs7754593 of TREML2, and HBV infection as well were associated with acute rejection. And, rs2127015 influences CD276 expression. Moreover, we established a risk assessment model, composited by statistically proved risk factors.ConclusionBy integrating both clinical and genetic variables, liver transplant recipients can be categorized into different risk groups, and might benefit from individualized therapies.

Circulating CXCR3-CCR6-CXCR5+CD4+ T cells are associated with acute allograft rejection in liver transplantation

Circulating T follicular helper (cTFH) cells have been demonstrated to be involved in B-cell-mediated alloreactive responses in kidney and liver transplantation; however, whether these cells are involved in acute liver allograft rejection after liver transplantation, and which subsets are involved, remains to be clarified. The present study aimed to investigate the profiles of cTFH cells in acute liver allograft rejection, including the CXC motif receptor 3 (CXCR3)+ chemokine receptor 6 (CCR6)− subset, the CXCR3−CCR6− subset, and the CXCR3−CCR6+ subset. Twelve liver transplant patients with acute rejection (AR) and 20 with no acute rejection (NAR) were enrolled in the study. The results showed that the proportion of CXCR3-CCR6-CXCR5+CD4+ T cells was significantly increased and the proportion of CXCR3−CCR6+CXCR5+CD4+ T cells was significantly decreased in patients with AR compared with patients with NAR. In addition, the proportion of CXCR3-CCR6-CXCR5+CD4+ T cells was positively correlated with the proportion of B cells in patients with AR. The level of serum interleukin (IL)-21 was higher in the AR group than in the NAR groups. Furthermore, the proportion of CXCR3-CCR6-CXCR5+CD4+ T cells was positively correlated with alanine amino transferase (ALT), whereas the proportion of CXCR3−CCR6+ CXCR5+CD4+ T cells was negatively correlated with ALT. B cells and TFH cells were detected in follicular-like structures in liver allograft tissues from patients with AR. These results suggest that CXCR3-CCR6-CXCR5+CD4+ T cells may be involved in acute allograft rejection after liver transplantation.

Association between CXCL9/10 polymorphisms and acute rejection of liver allograft.

While increased serum concentrations of CXCL9/10 are associated with acute cellular rejection (ACR) occurrence, the association between CXCL9/10 single nucleotide polymorphisms (SNPs) and ACR after liver transplantation (LT) remains unknown.In the present case-control study, polymorphisms of CXCL9 (rs10336) and CXCL10 (rs3921) were determined by polymerase chain reaction in 215 liver transplant recipients. ACR was defined as biopsy proven within 6 months after LT. As selected SNPs were in 3'-UTR region, their possible association with protein synthesis was assessed by measuring the plasma concentration of CXCL9/10 in a cohort of 40 new transplant patients using ELISA.There was no association between CXCL9/10 genotypes and overall incidence of ACR. However, patients with CXCL9 genotype AA developed ACR earlier than patients with GG genotype (P = .003), with similar results for CXCL10 gene (CC vs GG; P = .005). There was no statistically significant difference in plasma concentrations of CXCL9/10 between the rejectors and the non-rejectors. Of note, patients with AA CXCL9 genotype had significantly higher CXCL9 plasma concentrations than patients with AG (P = .01) or GG genotype (P = .045).In conclusion, the SNPs of CXCL9 (rs10336) and CXCL10 (rs3921) are not associated with the incidence of ACR. However, patients with CXCL9 genotype AA developed ACR earlier and the same genotype was associated with greater plasma concentrations suggesting the involvement of CXCL9 mediated processes in ACR development.

A Pilot Study of Mesenchymal Stem Cell Therapy for Acute Liver Allograft Rejection.

Acute allograft rejection remains common after liver transplantation despite modern immunosuppressive agents. In addition, the long‐term side effects of these regimens, including opportunistic infections, are challenging. This study evaluated the safety and clinical feasibility of umbilical cord‐derived mesenchymal stem cell (UC‐MSC) therapy in liver transplant patients with acute graft rejection. Twenty‐seven liver allograft recipients with acute rejection were randomly assigned into the UC‐MSC infusion group or the control group. Thirteen patients received one infusion of UC‐MSCs (1 × 106/kg body weight); one patient received multiple UC‐MSC infusions; 13 patients were used as controls. All enrolled patients received conventional immunosuppressive agents with follow‐up for 12 weeks after UC‐MSC infusions. No side effects occurred in treated patients. Four weeks after UC‐MSC infusions, alanine aminotransferase levels had decreased markedly and remained lower throughout the 12‐week follow‐up period. Importantly, allograft histology was improved after administration of UC‐MSCs. The percentage of regulatory T cells (Tregs) and the Treg/T helper 17 (Th17) cell ratio were significantly increased 4 weeks after infusions; in contrast, the percentage of Th17 cells showed a decreasing trend. In controls, the percentages of Tregs and Th17 cells and the Treg/Th17 ratio were statistically unchanged from the baseline measurements. Transforming growth factor beta 1 and prostaglandin E2 were increased significantly after UC‐MSC infusions; by contrast, there were no significant changes in controls. Our data suggest that UC‐MSC infusion for acute graft rejection following liver transplantation is feasible and may mediate a therapeutic immunosuppressive effect. Stem Cells Translational Medicine 2017;6:2053–2061

Sinusoid endotheliitis as a histological parameter for diagnosing acute liver allograft rejection

AIMTo investigated the feasibility of using sinusoidal endotheliitis (SE) as a histological marker for liver allograft rejection.METHODSWe compared the histological features of 88 liver allograft biopsies with acute cellular rejection (ACR) and 59 cases with no evidence of ACR. SE was scored as: (1) focal linear lifting up of the endothelial cells by lymphocytes with no obvious damage to adjacent hepatocytes; (2) focal disruption of the endothelial lining by a cluster of subendothelial lymphocytes (a group of > 3 lymphocytes); and (3) severe confluent endotheliitis with hemorrhage and adjacent hepatocyte loss.RESULTSThe sensitivity and specificity of SE was 81% and 85%, respectively. Using SE as the only parameter, the positive predictive value for ACR (PPV) was 0.89, whereas the negative predictive value for ACR (NPV) was 0.75. The correlation between RAI and SE was moderate (R = 0.44, P < 0.001) (Figure 3A), whereas it became strong (R = 0.65, P < 0.001) when correlating SE with the venous endotheliitis activity index only.CONCLUSIONOur data suggest that SE scoring could be a reliable and reproducible supplemental parameter to the existing Banff schema for diagnosing acute liver allograft rejection.

Risk factors for acute liver allograft rejection and their influences on treatment outcomes of rescue therapy in living donor liver transplantation.

Several clinical factors are reportedly correlated with acute cellular rejection (ACR) after liver transplantation. However, the factors that determine the response to rescue therapies remain unclear. A prospective database of 413 consecutive adult patients who underwent living donor liver transplantation (LDLT) was reviewed. Ninety-nine (24%) patients developed ACR after LDLT. A multivariate analysis revealed that a positive T-lymphocytotoxic test (odds ratio [OR], 3.85; P=.017), HLA-DR mismatch (OR, 2.99; P=.013), autoimmune disease (OR, 2.61; P=.001), and a younger recipient age (OR, 0.60 for +10years; P<.001) were independent risk factors for ACR. Among these, autoimmune disease was significantly correlated with refractoriness to the standard rescue therapy (53% vs 30%, P=.02) and relapse of cellular rejection (34% vs 16%, P=.04). After rescue therapy, 98 of the 99 (99%) patients eventually recovered from ACR and graft loss was observed in only one patient. None of the risk factors for ACR impaired both graft survival and overall survival after LDLT. Autoimmune liver disease is associated with refractoriness to rescue therapy for ACR and the relapse of rejection. However, ACR does not affect the long-term outcomes of LDLT if it is well controlled.

Cytomegalovirus-Induced γδ T Cells During Rejection: An Ambivalent T Cell

To the Editor: From a large cohort, Shi et al recently observed that cytomegalovirus (CMV) D+R- serostatus was associated with protection against late acute rejection of liver allografts (1.Shi XL de Mare-Bredemeijer EL Tapirdamaz O CMV primary infection is associated with donor-specific T cell hyporesponsiveness and fewer late acute rejections after liver transplantation.Am J Transplant. 2015; 15 (et al): 2431-2442Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar). Although this finding appears very interesting, some immunological hypotheses proposed in this article deserve several comments. First, the conclusion that CD8+ T cells from CMV-infected patients displayed a donor-specific hyporesponsiveness may be challenged because (1.Shi XL de Mare-Bredemeijer EL Tapirdamaz O CMV primary infection is associated with donor-specific T cell hyporesponsiveness and fewer late acute rejections after liver transplantation.Am J Transplant. 2015; 15 (et al): 2431-2442Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar) there is no difference in the level of donor-specific alloresponse at 6 months posttransplantation between D+R-, R+, and D-R- patients; (2.Couzi L Pitard V Moreau JF Merville P Dechanet-Merville J. Direct and indirect effects of cytomegalovirus-induced gammadelta T cells after kidney transplantation.Front Immunol. 2015; 6: 3Crossref PubMed Scopus (50) Google Scholar) no change in the level of donor-specific alloresponse was evaluated between pretransplantation and 6 months; and (3.Puig-Pey I Bohne F Benitez C Characterization of gammadelta T cell subsets in organ transplantation.Transplant Int. 2010; 23 (et al): 1045-1055Crossref PubMed Scopus (55) Google Scholar) the assessment of the response to third party as a control representative of a normal immune response is questionable. These data could also be interpreted as an increase of the third-party alloresponse observed at 6 months posttransplantation in D+R- patients, which could reflect the emergence of CMV-specific CD8+ T cells. Second, Kwekkeboom’s group reported that CMV primary infection patients had high levels of Vδ1 γδ T cells, which have been associated with operational tolerance after liver transplantation by Sanchez-Fueyo’s team a few years ago. However, before that, we and others had demonstrated that Vδ1, Vδ3, and Vδ5 γδ T cells (also designated as Vδ2neg γδ T cells) underwent a dramatic and stable expansion after CMV infection, in all solid organ transplant recipients, immunodeficient children, neonates, pregnant women, and healthy individuals. Similarly to CMV-specific CD8+ T cells, they exhibit an effector/memory TEMRA phenotype. In vitro, Vδ2neg γδ T cell lines exhibit a robust cytotoxic effector function against CMV-infected cells. In vivo, γδ T cells confer protection against murine CMV (2.Couzi L Pitard V Moreau JF Merville P Dechanet-Merville J. Direct and indirect effects of cytomegalovirus-induced gammadelta T cells after kidney transplantation.Front Immunol. 2015; 6: 3Crossref PubMed Scopus (50) Google Scholar). Therefore, Shi et al confirm this association since they demonstrated that CMV primary infection patients showed the highest Vδ1/Vδ2 γδ T cell ratio. In 2010, Sanchez-Fueyo’s team revised their seminal interpretation and showed that the overlap in the distribution of markers based on γδ T cells prevented their use as potentially diagnostic biomarkers of tolerance (3.Puig-Pey I Bohne F Benitez C Characterization of gammadelta T cell subsets in organ transplantation.Transplant Int. 2010; 23 (et al): 1045-1055Crossref PubMed Scopus (55) Google Scholar). According to them, the Vδ1/Vδ2 γδ T cell ratio was thus related to CMV infection and not restricted to tolerant liver recipients, consistent with our previous observations. In an opposite view to this association of Vδ1/Vδ2 γδ T cell ratio with operational tolerance, we even recently involved Vδ2neg γδ T cells as a new effector in rejection. γδ T cells express a broad range of activatory molecules and among them the CD16 molecule (FcγRIIIA), which is required for antibody-dependent cell cytotoxicity (ADCC). We showed that CMV infection deeply reshapes the CD16+ lymphocyte compartment composition in CMV+ recipients who exhibit an equal amount of CD16+ natural killer (NK) cells and CD16+ Vδ2neg γδ T cells (4.Couzi L Pitard V Sicard X Antibody-dependent anti-cytomegalovirus activity of human gammadelta T cells expressing CD16 (FcgammaRIIIa).Blood. 2012; 119 (et al): 1418-1427Crossref PubMed Scopus (93) Google Scholar). We also demonstrated that CMV-induced CD16+ Vδ2neg γδ T cells could perform ADCC as well as NK cells by interacting with donor-specific antibodies and contribute to antibody-mediated microcirculation injuries during rejection (5.Bachelet T Couzi L Pitard V Cytomegalovirus-responsive gammadelta T cells: Novel effector cells in antibody-mediated kidney allograft microcirculation lesions.J Am Soc Nephrol. 2014; 25 (et al): 2471-2482Crossref PubMed Scopus (32) Google Scholar). This implication of CMV-induced Vδ2neg γδ T cells in antibody-mediated rejection seemingly contrasts with the regulatory function attributed to Vδ1 γδ T cells in this article (Figure 1). The authors of this manuscript have no conflicts of interest to disclose as described by the American Journal of Transplantation.

Inhibition of Interferon Regulatory Factor 4 Attenuates Acute Liver Allograft Rejection in Mice.

Acute liver allograft rejection is a serious complication after liver transplantation. Interferon regulatory factor 4 (IRF4) is expressed predominantly in the immune system and plays an important role in its development and function. However, the role of IRF4 in liver transplantation has never been investigated. In our current study, to evaluate the effect of IRF4 inhibition on recipient survival, IRF4 siRNA, or control siRNA, or PBS was injected into the liver allograft recipients through caudal vein. The survival time of mice treated with IRF4 siRNA (MST=31.5days) was prolonged significantly compared with that of mice treated with PBS (MST=6days) or control siRNA (MST=6.5days) (P<0.001). IRF4 siRNA treatment displays lower induction of pro-inflammatory levels, including TNF-α, IL-6 and IFN-γ, and higher induction of anti-inflammatory IL-10 levels. Administration of anti-IL-10 into IRF4 siRNA-treated mice resulted in shortened allograft survival and increased rejection scores. Furthermore, IRF4 inhibition promotes M2 macrophage differentiation invivo and invitro. And inhibition of macrophages with GdCl3 reverses the prolonged liver allograft survival and decreased liver rejection scores induced by IRF4 siRNA. In conclusion, inhibition of IRF4 attenuates acute liver allograft rejection in mice, and this is associated with promoted M2 macrophage differentiation.

Association between a gain-of-function variant of PTPN22 and rejection in liver transplantation.

The protein tyrosine phosphatase nonreceptor 22 gene (PTPN22) encodes a strong T-cell regulator called lymphoid protein tyrosine phosphatase. Previously, PTPN22 was described as a susceptibility gene for autoimmunity because it contains single nucleotide polymorphisms (SNPs) associated with several autoimmune diseases. One SNP (rs2476601; 1858G>A) has emerged as a particularly potent risk factor for autoimmunity. We address the question whether PTPN22 polymorphisms are also associated with acute rejection after liver transplantation. We investigated the influence of six PTPN22 SNPs on the susceptibility to acute liver allograft rejection. Consequently, we carried out a retrospective study genotyping 345 German liver recipients at six SNP loci, which include rs2488457 (-1123G>C), rs33996649 (788C>T), rs2476601 (1858G>A), rs1310182 (-852A>G), rs1217388 (-2200G>A), rs3789604 (64434T>G). Our study enrolled 165 recipients who did not develop rejection, 123 who showed one rejection episode, and 57 patients who suffered from multiple acute rejections after transplantation. The 1858A allele containing genotypes (GA+AA) and the 1858A allele had a significantly higher frequency in the group of patients with multiple rejection episodes (35.1% and 18.4%) compared to rejection-free patients (15.8% and 7.9%; P=0.022 and 0.023). In contrast, we could not detect any association between rejection and the other tested SNPs. Additionally, we identified one haplotype contributing to risk of multiple rejections, however, exhibiting no stronger impact than the 1858A allele alone. We conclude that the 1858G>A SNP may confer susceptibility to multiple acute liver transplant rejections in the German population.

CD152 and PD-1 Down-Regulation on CD8 T Cells Is Associated With Human Acute Liver Allograft Rejection

PurposeTo investigate CD152 and PD-1 expression on T lymphocytes and the function of CD152- and PD-1–positive CD8 T cells in human acute liver allograft rejection. Materials and methodsSixty-three patients undergoing liver transplantation were enrolled in this study, including 26 cases with acute allograft rejection (Gr-AR) and 37 cases with stable allograft liver function (Gr-SF). The expression of CD152 and PD-1 on T lymphocytes and the expression of granzyme and perforin on CD152- and PD-1–positive CD8 T cells in peripheral blood were analyzed using flow cytometry. ResultsThe peripheral CD4/CD8 ratio in Gr-AR was significantly lower than that in Gr-SF (P < .01). The expression of CD152 and PD-1 on CD8 and CD4 T cells was significantly lower in Gr-AR than in Gr-SF (all P < .01). The expression of granzyme B and perforin was significantly higher in Gr-AR than in Gr-SF (P < .01). ConclusionsDown-regulation of the expression of negative costimulatory molecules such as CD152 and PD-1 on CD8 T cells may be associated with human acute liver allograft rejection.

Expression of Hemopexin in Acute Rejection of Rat Liver Allograft Identified by Serum Proteomic Analysis

Acute rejection (AR) and acceptance of allograft after liver transplantation (LTx) remain critical issues that need addressing to improve prognosis. We therefore performed rat orthotopic LTx and proteomic analyses to screen for immune response-related biomarkers in sera. Markers identified were validated at the mRNA and/or protein levels, and the molecules of interest were functionally explored. Compared with syngeneic controls, signs of AR as well as spontaneous acceptance were observed in hematoxylin and eosin-stained sections of liver allografts. In accordance with the severity of AR, 30 protein spots displaying significant changes in abundance were identified using two-dimensional differential gel electrophoresis. Ultimately, 14 serum proteins were sequenced and five spots of interest were identified as hemopexin (HPX). Expression of HPX was significantly and inversely associated with the severity of AR at both the mRNA and protein levels. In vitro, Mt-1, Ho-1, Fth, Ifn-γ, and Il-17 transcripts were significantly upregulated in lysates of lymphocytes stimulated with HPX, whereas Il-10 markedly was remarkably downregulated. Interferon-γ, IL-10, and IL-17 proteins in the supernatant of HPX-stimulated lymphocytes were significantly altered in keeping with the mRNA level. Our data facilitated the generation of a proteomic profile to enhance the understanding of rat liver AR. In view of finding that the HPX serum level is negatively associated with the severity of AR of rat liver allograft, we propose that in vitro treatment with HPX regulates cytokine expression in rat lymphocytes.

Prevention of acute liver allograft rejection by IL-10-engineered mesenchymal stem cells

Hepatic allograft rejection remains a challenging problem, with acute rejection episode as the major barrier for long-term survival in liver transplant recipients. To explore a strategy to prevent allograft rejection, we hypothesized that mesenchymal stem cells (MSCs) genetically engineered with interleukin-10 (IL-10) could produce beneficial effects on orthotopic liver transplantation (OLT) in the experimental rat model. Syngeneic MSCs transduced with IL-10 were delivered via the right jugular vein 30 min post-orthotopic transplantation in the rat model. To evaluate liver morphology and measure cytokine concentration, the blood and liver samples from each animal group were collected at different time-points (3, 5 and 7 days) post-transplantation. The mean survival time of the rats treated with MSCs-IL-10 was shown to be much longer than those treated with saline. According to Banff scheme grading, the saline group scores increased significantly compared with those in the MSCs-IL-10 group. Retinoid acid receptor-related orphan receptor gamma t (RORγt) expression was more increased in the saline group compared to those in the MSCs-IL-10 group in a time-dependent manner; forkhead box protein 3 (FoxP3) expression also decreased significantly in the saline group compared with those in the MSCs-IL-10 group in a time-dependent manner. The expression of cytokines [IL-17, IL-23, IL-6, interferon (IFN)-γ and tumour necrosis factor (TNF)-α] in the saline groups increased significantly compared with the time-point-matched MSCs-IL-10 group, whereas cytokine expression of (IL-10, TGF-β1) was deceased markedly compared to that in the MSCs-IL-10 group. These results suggest a potential role for IL-10-engineered MSC therapy to overcome clinical liver transplantation rejection.

Characteristics of Vδ1+ and Vδ2+ γδ T cell subsets in acute liver allograft rejection

BackgroundTo investigate the characteristics of γδ T cells as well as the Vδ1+ and Vδ2+ subsets in the peripheral blood in liver allograft recipients. MethodsSixty-three liver transplant recipients were enrolled in this study: 26 cases with acute allograft rejection (Gr-AR), and 37 cases with stable allograft liver function (Gr-SF). The frequencies of γδ T cells, the Vδ1+ and Vδ2+ subsets, and interleukin (IL)-10-producing Vδ1+ γδ T cells in the peripheral blood were analyzed by flow cytometry. The relationship between liver function parameters and the Vδ1+/Vδ2+ ratio was analyzed. ResultsThe frequency of the Vδ1+ subset and the Vδ1+/Vδ2+ ratio in Gr-SF was significantly higher than that in Gr-AR; in contrast, the frequency of the Vδ2+ subset in Gr-SF was markedly lower than that in Gr-AR. In addition, there was no significant difference in the frequency of γδ T cells between the Gr-AR and Gr-SF groups. Moreover, there was a significant negative correlation between the Vδ1+/Vδ2+ ratio with the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in Gr-AR. ConclusionsVδ1+ γδ T cells may have a potential role in maintaining stable graft liver function, and Vδ2+ γδ T cells may be associated with liver allograft rejection. The Vδ1+/Vδ2+ ratio could serve as a prognostic marker for acute rejection after liver transplantation.