Küpffer cells promote acute rejection via induction of Th17 differentiation in rat liver allografts

BACKGROUND

Th17, a newly identified CD4+ T-cell subset, has been implicated in transplant rejection. Differentiation of Th17 cells is associated with transforming growth factor-β (TGF-β) and interleukin-6 (IL-6), which are the main products of Küpffer cells.

OBJECTIVE

To determine whether Küpffer cells promote acute liver allograft rejection by inducing Th17 cell differentiation.

METHODS

A rat model of allogeneic liver transplantation using Dark Agouti (DA) to Brown Norway (BN) rats was established with or without gadolinium chloride (GdCl(3)) pretreatment. Isogeneic liver transplantation (BN to BN) was performed as a control. Concentrations of cytokines secreted by Küpffer cells or Th17-related cytokines detected in the liver and peripheral blood were analyzed using immunohistochemistry assays, flow cytometry, and enzyme-linked immunosorbent assays. Survival differences were compared between treatment groups. In vitro, Küpffer cells from liver grafts were isolated and co-cultured with naïve CD4 T cells.

RESULTS

Both Küpffer cells and Th17 cells infiltrated liver allografts, accompanied by an increase in concentrations of IL-6 and TGF-β. Pretreatment with GdCl(3) attenuated intragraft infiltration of Küpffer cells and Th17 cells, and decreased IL-6 and TGF-β concentrations. Liver function improved after pretreatment, and mean (SD) survival time was prolonged, compared with the control group (16.33 [0.96] days vs 11.50 [0.99] days, respectively; P < .01). In vitro, Küpffer cells from livers with allografts secreted significantly higher concentrations of IL-6 and TGF-β and induced Th17 differentiation more effectively compared with livers with isografts (30.8% vs 8.1%, respectively).

CONCLUSION

Küpffer cells have the potential to induce Th17 cells by secreting IL-6 and TGF-β, and as a result, promote acute liver allograft rejection.

Naloxone in the management of hepatic encephalopathy

BACKGROUND/AIM

This study aimed to assess the effectiveness and safety of naloxone in the management of hepatic encephalopathy (HE).

METHODS

Cochrane collaboration methodology was used in a meta-analysis of randomized controlled trials of naloxone therapy for HE.

RESULTS

Seventeen randomized trials were identified with 15 studies involving 1054 patients meeting criteria for inclusion. Naloxone use was associated with a significant improvement in HE [relative risk (RR) 1.46; 95% confidence interval (CI) 1.27-1.67; P = 0.0005]. This comparison showed statistical heterogeneity (P < 0.10, and χ2 = 44.93). Subgroup analysis indicated naloxone administered parenterally by intermittent or continuous infusions to be effective (RR 1.34; 95% CI 1.17-1.53; P < 0.0001). A significant in trials by infusion route (RR 1.42; 95% CI 1.19-1.69; P < 0.0001) interaction was observed.

CONCLUSIONS

Naloxone may improve HE. However, published data are limited.

Immune suppression produced by intrathymic inoculation with xenogeneic antigen and whole-body γ-irradiation in a pig-to-monkey heart transplantation model

OBJECTIVE

To validate the use of pig-to-monkey transplantation as an experimental animal model for study of the induction of immune suppression of cardiac xenografts via intrathymic inoculation with xenogeneic spleen cells and whole-body γ-irradiation.

MATERIALS AND METHODS

Donors (Meishan pigs) and recipients (Rhesus monkeys) were randomized into 3 groups. Group 2 was the control group; group 2 received whole-body irradiation, and group 3 received whole-body irradiation and intrathymic inoculation. In each group, survival time of heterotopic heart xenografts in monkeys were observed. A mixed lymphocyte reaction assay with (3)H thymidine was used to examine changes in lymphocyte function in all groups on the day of transplantation. In each group, recipient serum was harvested for analysis of IL-2 and IL-10 concentrations.

RESULTS

Mean (SD) survival time of donor hearts in group 3 was significantly longer (91.1 [22.8] hours) than in group 1 (36.6 [5.8] hours) (P < .01). The results of mixed lymphocyte reaction assay demonstrated a significant reduction in the stimulation index in group 3 compared with groups 1 and 2 (P < .01) when recipient splenocytes responded to the donor stimulator. The IL-2 concentration in recipients in all groups was much higher during rejection of xenografts than before transplantation (P < .01).

CONCLUSION

These results suggest that pretreatment with intrathymic inoculation or whole-body irradiation induces T-cell immunosuppression. The IL-2 concentration is closely correlated with xenograft rejection.

Vertebral fractures in the elderly may not always be "osteoporotic"

INTRODUCTION

Vertebral fractures in the elderly are often assumed to be "osteoporotic" and require anti-osteoporosis therapy. However, some of these fractures may represent traumatic injuries to vertebrae that have comparatively normal bone mineral density (BMD). We hypothesize that radiographic appearances can be used to differentiate between "osteoporotic" fractures of vertebrae with low BMD and strength, and "traumatic" fractures of vertebrae with normal BMD and strength.

METHODS

73 cadaveric specimens (each comprising two vertebrae with the intervening intervertebral disc and ligaments) were obtained from donors aged 42 to 91 (mean 74) years. Areal BMD was measured in the lateral projection for each vertebral body, using DXA. Each specimen was secured in metal cups containing dental plaster, and compressed to failure at 3mm/s on a computer-controlled materials testing machine. Mechanical failure was detected by a reduction in the gradient of the load-deformation curve. Compressive deformation for each specimen was limited to 4mm in order to prevent gross destruction of the vertebra. Radiographs, obtained before and after mechanical loading, were assessed by an experienced radiologist (GJ) who was blinded to BMD and mechanical data. The algorithm-based qualitative method (ABQ) was used to assign each specimen to two possible outcomes: no discernible fracture of either vertebra, or fracture. The latter were further classified into specimens with osteoporotic fracture and those with traumatic fracture, by applying additional criteria for differential diagnosis. The relationship of failure load to BMD was tested using correlation. BMD and failure load for the three diagnostic outcomes were compared using one-way analysis of variance (ANOVA).

RESULTS

Failure load was proportional to BMD (R=0.63, p<0.001). "Osteoporotic," "traumatic" and "no discernible" fractures were reported in 16, 26 and 31 specimens respectively. "Traumatic" fracture specimens had higher BMD and failed at higher loads than "osteoporotic" fracture specimens (p<0.05).

CONCLUSIONS

Some vertebral fractures in the elderly may be traumatic rather than osteoporotic in origin. Our radiological criteria help to differentiate between them.

Video-assisted repair of cervical lung hernia

Lung hernia is an extremely rare condition and the treatments vary. We report a case of cervical lung hernia without any trauma. The patient underwent video-assisted repair with a satisfactory result.

Role of human CYP1A1 and NAT2 in 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine-induced mutagenicity and DNA adducts

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is carcinogenic in multiple organs and numerous species. Bioactivation of PhIP is initiated by PhIP N(2)-hydroxylation catalysed by cytochrome P450s. Following N-hydroxylation, O-acetylation catalysed by N-acetyltransferase 2 (NAT2) is considered a further possible activation pathway. Genetic polymorphisms in NAT2 may modify cancer risk following exposure. Nucleotide excision repair-deficient Chinese hamster ovary (CHO) cells stably transfected with human cytochrome P4501A1 (CYP1A1) and a single copy of either NAT2*4 (rapid acetylator) or NAT2*5B (slow acetylator) alleles were used to test the effect of CYP1A1 and NAT2 polymorphism on PhIP genotoxicity. Cells transfected with NAT2*4 had significantly higher levels of N-hydroxy-PhIP O-acetyltransferase (p = 0.0150) activity than cells transfected with NAT2*5B. Following PhIP treatment, CHO cell lines transfected with CYP1A1, CYP1A1/NAT2*4 and CYP1A1/NAT2*5B each showed concentration-dependent cytotoxicity and hypoxanthine phosphoribosyl transferase (hprt) mutagenesis not observed in untransfected CHO cells. dG-C8-PhIP was the primary DNA adduct formed and levels were dose dependent in transfected CHO cells in the order: CYP1A1 < CYP1A1 and NAT2*5B < CYP1A1 and NAT2*4, although levels did not differ significantly (p > 0.05) following one-way analysis of variance. These results strongly support activation of PhIP by CYP1A1 with little effect of human NAT2 genetic polymorphism on mutagenesis and DNA damage.

Activity identification of chimeric anti-caspase-3 mRNA hammerhead ribozyme in vitro and in vivo

To study the expression activity of various vectors containing anti-caspase-3 ribozyme cassettes in vivo, and to further study the role of caspas-3 in the apoptotic pathway, we constructed anti-caspase-3 hammerhead ribozyme embedded into the human snRNA U6, and detected the activity of the ribozyme in vitro and in vivo. Meanwhile we compared it with the self-cleaving hammerhead ribozymes that we previously studied, and with the general ribozyme, cloned into RNA polymerase II expression systems. The results showed that the three ribozymes, p1.5RZ107, pRZ107 and pU6RZ107 had the correct structure, and that they could cleave caspase-3 mRNA exactly to produce two fragments: 143nt/553nt. p1.5RZ107 has the highest cleavage efficiency in vitro, almost 80%. However, the U6 chimeric ribozyme, pU6RZ107, has the highest cleavage activity in vivo, almost to 65%, though it has lower cleavage activity in vitro. The cleavage results demonstrated that the pU6RZ107, the U6 chimeric ribozyme, could more efficiently express and downregulate the level of caspase-3 in vivo, and the ribozyme could provide an alternative approach to the research into the mechanism of apoptosis and human gene therapy also.

Activation of complement in the discordant heart xenotransplantation of pig-to-monkey model and the impact of intrathymic inoculation of xenogeneic antigen combined with whole-body gamma-radiation

OBJECTIVE

This study investigated changes in complement in discordant heart xenotransplantation using a pig-to-monkey model as well as the impact of intrathymic inoculation (IT) with xenogeneic antigen combined with whole-body gamma-radiation (WBI).

METHODS

In this experiment, pigs and monkeys selected as donors and recipients, respectively, were randomly divided into three groups: a blank group (group A), a whole-body irradiation group (group B) and an irradiation plus intrathymic injection group (group C). In every group, monkeys underwent heterotopic heart xenotransplantation.

RESULTS

The results showed that the survival of donor hearts in group C was significantly longer than that of group A (P < .01). In mixed lymphocyte reactions, there was a significant reduction of the stimulation index in group C compared with group A. After xenotransplantation, the level of xenoreactive antibody in group C rose slower than that in group A or group B (P < .01). After rejection, the levels of CD46 and C3 declined greatly.

CONCLUSIONS

These results suggested that pretreatment with IT and WBI induced T-cell immunosuppression, restraining elicited xenoreactive antibody production of both immunoglobulin M and immunoglobulin G classes. However, it did not hinder complement activation via the classical pathway during hyperacute rejection and consequent xenograft rejection.

Lysophosphatidic acid-induced platelet shape change revealed through LPA(1-5) receptor-selective probes and albumin

Lysophosphatidic acid (LPA), a component of mildly-oxidized LDL and the lipid rich core of atherosclerotic plaques, elicits platelet activation. LPA is the ligand of G protein-coupled receptors (GPCR) of the EDG family (LPA(1-3)) and the newly identified LPA(4-7) subcluster. LPA(4), LPA(5) and LPA(7) increase cellular cAMP levels that would induce platelet inhibition rather than activation. In the present study we quantified the mRNA levels of the LPA(1-7) GPCR in human platelets and found a rank order LPA(4) = LPA(5) > LPA(7) > LPA(6) = LPA(2) >> LPA(1) > LPA(3). We examined platelet shape change using a panel of LPA receptor subtype-selective agonists and antagonists and compared them with their pharmacological profiles obtained in heterologous LPA(1-5) receptor expression systems. Responses to different natural acyl and alkyl species of LPA, and octyl phosphatidic acid analogs, alpha-substituted phosphonate analogs, N-palmitoyl-tyrosine phosphoric acid, N-palmitoyl-serine phosphoric acid were tested. All of these compounds elicited platelet activation and also inhibited LPA-induced platelet shape change after pre-incubation, suggesting that receptor desensitization is likely responsible for the inhibition of this response. Fatty acid free albumin (10 microM) lacking platelet activity completely inhibited platelet shape change induced by LPA with an IC(50) of 1.1 microM but had no effect on the activation of LPA(1,2,3,&5) expressed in endogenously non-LPA-responsive RH7777 cells. However, albumin reduced LPA(4) activation and shifted the dose-response curve to the right. LPA(5) transiently expressed in RH7777 cells showed preference to alkyl-LPA over acyl-LPA that is similar to that in platelets. LPA did not increase cAMP levels in platelets. In conclusion, our results with the pharmacological compounds and albumin demonstrate that LPA does not induce platelet shape change simply through activation of LPA(1-5), and the receptor(s) mediating LPA-induced platelet activation remains elusive.

Rapid, accurate determination of multidrug resistance in M. tuberculosis isolates and sputum using a biochip system

OBJECTIVE

To develop and evaluate a rapid biochip system for the determination of multidrug-resistant tuberculosis (MDR-TB) in Mycobacterium tuberculosis isolates and clinical sputum samples.

DESIGN

We developed a total solution-based system, including a biochip kit, apparatus for sample preparation, hybridisation, washing and data acquisition, and dedicated software for automated diagnosis. The biochip simultaneously identifies M. tuberculosis and detects the most commonly found mutations in the rpoB, katG and inhA genes. The system was assessed with 330 mycobacterial isolates and 129 sputum samples for rifampicin (RMP), and with 205 isolates and 105 sputum samples for isoniazid (INH), and then compared to DNA sequencing and conventional drug susceptibility testing (DST).

RESULTS

The entire biochip assay took 6 h. The concordance rate between the biochip assay and the DNA sequencing results was 100%. Compared to conventional DST, the concordance rates were 91.8% for isolates and 94.6% for sputum samples for RMP resistance, and 70.2% for isolates and 78.1% for sputum samples for INH resistance.

CONCLUSION

The biochip system provides a simple, rapid, reliable and accurate clinical assay for the parallel detection of M. tuberculosis and prevalent MDR-TB in a 6 h procedure, using either culture isolates or sputum samples for diagnosis.