Yih Jyh Lin

THE INNATE IMMUNE RESPONSE AND ACTIVATION OF COAGULATION IN α1,3-GALACTOSYLTRANSFERASE GENE-KNOCKOUT XENOGRAFT RECIPIENTS

Background. The role of the innate immune system in the development of thrombotic microangiopathy (TM) after α1,3-galactosyltransferase gene-knockout (GTKO) pig organ transplantation in primates is uncertain. Methods. Twelve organs (nine hearts, three kidneys) from GTKO pigs were transplanted into baboons that received no immunosuppressive therapy, partial regimens, or a full regimen based on costimulation blockade. After graft failure, histologic and immunohistologic examinations were carried out. Results. Graft survival of less than 1 day was prolonged to 2 to 12 days with partial regimens (acute humoral xenograft rejection) and to 5 and 8 weeks with the full regimen (TM). Clinical or laboratory features of consumptive coagulopathy occurred in 7 of 12 baboons. Immunohistochemistry demonstrated IgM, IgG, and complement deposition in most cases. Histopathology demonstrated neutrophil and macrophage infiltrates, intravascular fibrin deposition, and platelet aggregation (TM). Grafts showed expression of primate tissue factor (TF), with increased mRNA levels, and TF was also expressed on baboon macrophages/monocytes infiltrating the graft. Conclusions. Our data suggest that (1) irrespective of the presence or absence of the adaptive immune response, early or late xenograft rejection is associated with activation of the innate immune system; and (2) porcine endothelial cell activation and primate TF expression by recipient innate immune cells may both contribute to the development of TM.

In vitro investigation of pig cells for resistance to human antibody-mediated rejection.

Although human complement‐dependent cytotoxicity (CDC) of α1,3‐galactosyltransferase gene‐knockout (GTKO) pig cells is significantly weaker than that of wild‐type (WT) cells, successful xenotransplantation will require pigs with multiple genetic modifications. Sera from healthy humans were tested by (i) flow cytometry for binding of IgM/IgG, and (ii) CDC assay against peripheral blood mononuclear cells and porcine aortic endothelial cells from five types of pig – WT, GTKO, GTKO transgenic for H‐transferase (GTKO/HT), WT transgenic for human complement regulatory protein CD46 (CD46) and GTKO/CD46. There was significantly higher mean IgM/IgG binding to WT and CD46 cells than to GTKO, GTKO/HT, and GTKO/CD46, but no difference between GTKO, GTKO/HT, and GTKO/CD46 cells. There was significantly higher mean CDC to WT than to GTKO, GTKO/HT, CD46, and GTKO/CD46 cells, but no difference between GTKO and GTKO/HT. Lysis of GTKO/CD46 cells was significantly lower than that of GTKO or CD46 cells. CD46 expression provided partial protection against serum from a baboon sensitized to a GTKO pig heart. GTKO/CD46 cells were significantly resistant to lysis by human serum and sensitized baboon serum. In conclusion, the greatest protection from CDC was obtained by the combination of an absence of Gal expression and the presence of CD46 expression, but the expression of HT appeared to offer no advantage over GTKO. Organs from GTKO/CD46 pigs are likely to be significantly less susceptible to CDC.

Allosensitized humans are at no greater risk of humoral rejection of GT‐KO pig organs than other humans

Abstract:  Background:  The availability of pigs homozygous for α1,3‐galactosyltransferase gene‐knockout (GT‐KO) has enabled study of the incidence and cytotoxicity of primate antibodies directed to antigens other than Galα1,3Gal (Gal), termed non‐Gal antigens.

A review of obturator hernia and a proposed algorithm for its diagnosis and treatment.

The aim of this article is to provide a review of six patients with the various stages of obturator hernia and a diagnostic and therapeutic strategy in suspected cases. Obturator hernia is relatively rare and is a diagnostic challenge. It is a significant cause of intestinal obstruction, especially in emaciated elderly women with chronic disease. A palpable groin mass is not common in these patients because the hernia mass is usually concealed beneath the pectineus muscle. The high mortality is directly related to the delayed recognition, with resultant ruptured gangrenous bowel, and to the high incidence of patients with concurrent medical illness. A total of six patients with obturator hernias were treated at this hospital between 1994 and 2004, and one of these patients was diagnosed and treated by elective laparoscopy. We reviewed these six cases and examined the clinical presentation, age, body weight, associated medical conditions, preoperative diagnosis, operative findings, complications, and outcome in this retrospective study. We concluded that we cannot shorten the time from onset of symptoms to admission, but what we can do is to make a rapid evaluation and surgical intervention to reduce the morbidity and mortality from obturator hernia. The approaches to different presentation of obturator hernia and diagnostic role of CT scan are also discussed.

Randomised clinical trial: comparison of two everolimus dosing schedules in patients with advanced hepatocellular carcinoma

Deregulation of mammalian target of rapamycin (mTOR) signalling is common in human hepatocellular carcinoma (HCC).

Reappraisal of HLA Antibody Analysis and Crossmatching in Kidney Transplantation

Enzyme-linked immunosorbent assay (ELISA) and flow cytometric techniques have been introduced to overcome the limited sensitivity and specificity of the CDC assay. This retrospective study used lambda antigen tray-mixed screening and Luminex HLA class I and II specificity assays to re-examine: (1) the accuracy with which detection of HLA antibody and specificity by ELISA predicts pretransplantation National Institutes of Health (NIH)/Centers for Disease Control and Prevention (CDC) crossmatch; and (2) a comparison of Luminex and ELISA methods to detect HLA antibodies. Sera from 481 patients awaiting kidney transplantation were tested using the ELISA method lambda antigen tray-mixed and using NIH-CDC to determine how well HLA antibodies detected using ELISA predicted crossmatches using CDC. Pretransplantation sera from 48 patients with follow-up data were retested using both ELISA lambda antigen tray-mixed and Luminex to compare the efficacy of the 2 methods.

Suppressive efficacy and proliferative capacity of human regulatory T cells in allogeneic and xenogeneic responses.

Background. An understanding of the mechanisms that suppress the human anti-pig cellular response is key for xenotransplantation. We have compared the ability of human regulatory T cells (Tregs) to suppress xenogeneic and allogeneic responses in vitro. Methods. Human peripheral blood mononuclear cells (PBMC), CD4+T cells, or CD4+CD25−T cells were stimulated with irradiated human or wild type (WT) or &agr;1,3-galactosyltransferase gene-knockout (GT-KO) pig PBMC in the presence or absence of human CD4+CD25highTregs. In separate experiments, 5- (and 6)-carboxyfluorescein diacetate succinimidyl ester-labeled human CD4+T cells were stimulated with human or pig PBMC. The expansion and precursor frequencies of allo- and xeno-reacitve Tregs were assessed by labeling with FoxP3 mAb and flow cytometric analysis. Results. The responses of human PBMC, CD4+T cells, and CD4+CD25−T cells to pig PBMC were stronger than to human PBMC (P<0.05). Human anti-GT-KO responses were weaker than anti-WT responses (P<0.05). Human CD4+CD25highTregs suppressed proliferation of CD4+CD25−T cells to both human and pig PBMC stimulator cells with the same efficiency. Alloreactive CD4+CD25+FoxP3high responder T cells proliferated more than their xenoreactive counterparts (P<0.05), although xenoreactive CD4+CD25+T cells proliferated more than alloreactive cells (P<0.05). There was no difference in precursor frequency between allo- and xeno-reactive CD4+CD25+FoxP3high cells. Conclusions. Human T-cell responses to pig cells are stronger than to allogeneic cells. The human response to GT-KO PBMC is weaker than to WT PBMC. Although human Tregs can suppress both responses, expansion of CD4+CD25+FoxP3high cells against pig PBMC is weaker than against human PBMC. More human Tregs may be required to suppress the stronger xenogeneic response.

Hepatitis B Virus X Protein Upregulates mTOR Signaling through IKKβ to Increase Cell Proliferation and VEGF Production in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), a major cause of cancer-related death in Southeast Asia, is frequently associated with hepatitis B virus (HBV) infection. HBV X protein (HBx), encoded by a viral non-structural gene, is a multifunctional regulator in HBV-associated tumor development. We investigated novel signaling pathways underlying HBx-induced liver tumorigenesis and found that the signaling pathway involving IκB kinase β (IKKβ), tuberous sclerosis complex 1 (TSC1), and mammalian target of rapamycin (mTOR) downstream effector S6 kinase (S6K1), was upregulated when HBx was overexpressed in hepatoma cells. HBx-induced S6K1 activation was reversed by IKKβ inhibitor Bay 11-7082 or silencing IKKβ expression using siRNA. HBx upregulated cell proliferation and vascular endothelial growth factor (VEGF) production, and these HBx-upregulated phenotypes were abolished by treatment with IKKβ inhibitor Bay 11-7082 or mTOR inhibitor rapamycin. The association of HBx-modulated IKKβ/mTOR/S6K1 signaling with liver tumorigenesis was verified in a HBx transgenic mouse model in which pIKKβ, pS6K1, and VEGF expression was found to be higher in cancerous than non-cancerous liver tissues. Furthermore, we also found that pIKKβ levels were strongly correlated with pTSC1 and pS6K1 levels in HBV-associated hepatoma tissue specimens taken from 95 patients, and that higher pIKKβ, pTSC1, and pS6K1 levels were correlated with a poor prognosis in these patients. Taken together, our findings demonstrate that HBx deregulates TSC1/mTOR signaling through IKKβ, which is crucially linked to HBV-associated HCC development.

A clustered ground‐glass hepatocyte pattern represents a new prognostic marker for the recurrence of hepatocellular carcinoma after surgery

The recurrence of hepatocellular carcinoma (HCC) after hepatectomy is a serious event. It has been demonstrated that different ground‐glass hepatocyte (GGH) patterns harbor specific hepatitis B virus (HBV) pre‐S deletion mutants and represent preneoplastic lesions in chronic HBV infection. In the current study, the authors investigated whether a specific GGH pattern in nontumorous liver tissues was associated with the recurrence of HBV‐related HCC after surgery.

Lin28B Is an Oncofetal Circulating Cancer Stem Cell-Like Marker Associated with Recurrence of Hepatocellular Carcinoma

By using an expressed sequence tag bioinformatic algorithm, we identified that Lin28 homolog B (Lin28B) may have an oncofetal expression pattern which may facilitate detecting cancer cells in adults. It is also reported to be a potential marker for cancer stem cells. Therefore, we sought to verify oncofetal-stemness characters of Lin28B and test its potential as a circulating cancer stem cell-like marker in adult HCC patients. Lin28B mRNA was examined in a panel of fetal tissue, adult tissue and tumors. Lin28B was over-expressed or knocked down in HepG2 cells to evaluate its potential as a stem cell-like marker. RT-qPCR for Lin28B was performed in the peripheral blood mononuclear cells from patients with HCC receiving surgery (n=96) and non-HCC controls (n=60) and analyzed its clinical significance. Lin28B showed an oncofetal expression pattern. Its overexpression could upregulate stemness markers (OCT4, Nanog and SOX2) and enhance tumorsphere formation in vitro. Lin28B knockdown had opposite effects. Circulating Lin28B was detected in peripheral blood mononuclear cells in 3 cases (5%) of non-HCC controls and 32 cases (33.3%) of HCC patients. In HCC patients, circulating Lin28B was associated with high tumor grade (P=0.046), large size (P=0.005), high AJCC stage (P=0.044) and BCLC stage (P=0.017). Circulating Lin28B was significantly associated with decreased recurrence-free survival (P<0.001). Circulating Lin28B separated early stage HCC into 2 recurrence-free survival curves (P=0.003). In multivariate analysis, circulating Lin28B was an independent variable associated with early recurrence (P=0.045) and recurrence in early stage HCC (P=0.006). In conclusion, the oncofetal gene Lin28B is a potential oncofetal cancer-stem-cell-like circulating tumor cell marker that correlates with HCC recurrence after hepatectomy. Circulating Lin28B could refine early AJCC stages. Our finding supports the possible use of a TNMC (C for circulating tumor cells) staging system in HCC.