Prevention of hyperacute rejection in a model of orthotopic liver xenotransplantation from pig to baboon using polytransgenic pig livers (CD55, CD59, and H-transferase)

INTRODUCTION

The search for alternative sources for transplant organs leads us to the search for animals as an inexhaustible source of organs. The objective of this study was to analyze whether livers from polytransgenic pigs expressing the human complement regulatory proteins CD55 (hDAF), CD59, and alfa alpha1,2-fucosyltransferase (H-transferase), protected against hyperacute rejection after orthotopic liver xenotransplantation to a baboon and also to study pig liver function in a nonhuman primate.

MATERIALS AND METHODS

Nine liver transplants from pig to baboon were divided into two groups: a control group (n = 4) of genetically unmodified pigs and an experimental group (n = 5) of pigs transgenic for CD55, CD59, and H-transferase as donors. All the donating piglets obtained through hysterectomy were maintained in specific pathogen-free conditions. The selection of transgenic pig donors followed demonstration of transgene expression using monoclonal antibodies (antiCD55, antiCD59) and immunohistological studies on liver biopsies.

RESULTS

All animals in the control group developed hyperacute rejection with survival rates less than 16 hours without function of transplanted livers. In the experimental group none of the animals suffered hyperacute rejection. Survival in this group was between 13 and 24 hours. The livers were functional, producing bile and maintaining above 35% prothrombin activity. Only in one case was there primary dysfunction of the xenograft.

CONCLUSION

Polytransgenic livers for complement regulatory proteins prevent hyperacute rejection when xenotransplanted into a baboon.

Protection against hyperacute xenograft rejection of transgenic rat hearts expressing human decay accelerating factor (DAF) transplanted into primates

BACKGROUND

Production of transgenic pigs for multiple transgenes is part of a potential strategy to prevent immunological events involved in xenograft rejection. Use of a genetically engineerable rodent as a donor in primates could allow testing in vivo of the effects of different transgenes on controlling xenograft rejection. As a first step in the development of a donor containing multiple transgenes, transgenic rats for human decay-accelerating factor (DAF) were used as heart donors to test their resistance against complement (C)-mediated rejection by non-human primates.

MATERIALS AND METHODS

Transgenic rats were generated by using a construct containing the human DAF cDNA under the transcriptional control of the endothelial cell (EC)-specific human ICAM-2 promoter. DAF expression was evaluated by immunohistology and by FACS analysis of purified ECs. Resistance of transgenic hearts against C-mediated damage was evaluated by ex vivo perfusion with human serum and by transplantation into cynomolgus monkeys.

RESULTS

Immunohistological analysis of DAF expression in several organs from two transgenic lines showed uniform expression on the endothelium of all blood vessels. ECs purified from transgenic hearts showed 50% DAF expression compared to human ECs and >70% reduction of C-dependent cell lysis compared to control rat ECs. Hemizygous transgenic hearts perfused with human serum showed normal function for >60 min vs. 11. 2 +/- 1.7 min in controls. Hemi- or homozygous transgenic hearts transplanted into cynomolgus monkeys showed longer survival (15.2 +/- 7 min and >4.5 hr, respectively) than controls (5.5 +/- 1.4 min). In contrast to hyperacutely rejected control hearts, rejected homozygous DAF hearts showed signs of acute vascular rejection (AVR) characterized by edema, hemorrhage, and an intense PMN infiltration.

CONCLUSIONS

We demonstrate that endothelial-specific DAF expression increased heart transplant survival in a rat-to-primate model of xenotransplantation. This will aid in the analysis of AVR and of new genes that may inhibit this form of rejection, thus helping to define strategies for the production of transgenic pigs.

Anti-transglutaminase antibodies and coeliac disease

BACKGROUND

Anti-endomysial antibodies have high specificity for coeliac disease but measurements are limited by the requirement for monkey oesophagus, a substrate that is expensive, and of limited availability and ethical acceptance. Tissue transglutaminase has recently been identified as the endomysial autoantigen in coeliac disease.

AIMS

To examine the validity of serum tissue transglutaminase antibody levels in patients with coeliac disease and to assess their sensitivity and specificity against standard serological tests.

METHODS

Serum IgA anti-tissue transglutaminase antibody titres (measured by ELISA), IgA anti-gliadin antibody titres (measured by a commercial ELISA) and anti-endomysial antibody titres (measured by indirect immunofluorescence) were determined in 46 untreated and 14 treated patients biopsy-proven coeliac disease and 145 disease and healthy controls.

RESULTS

All patients with untreated coeliac disease were positive for anti-endomysial and anti-tissue transglutaminase antibodies (sensitivity 100%). Seventy-one per cent of treated coeliac patients were anti-tissue transglutaminase antibody negative. Five of 145 disease and healthy controls had low titres of anti-tissue transglutaminase antibody (specificity 97%); no controls were anti-endomysial antibody positive.

CONCLUSIONS

Our results demonstrated the sensitivity and specificity of IgA anti-tissue transglutaminase antibodies to correlate highly with anti-endomysial antibodies in the diagnosis of coeliac disease. The ELISA for IgA anti-tissue transglutaminase antibodies is quantitative and easy to perform and is a valid alternative to indirect immunofluorescence for anti-endomysial antibodies in screening for suspected coeliac disease.

Dual posttranscriptional targets of retinoic acid-induced gene expression

Retinoic acid-induced differentiation of the pre-osteoblastic cell line, UMR 201, is associated with a marked increase in the proficiency of posttranscriptional nuclear processing of alkaline phosphatase mRNA. In this study we attempted to correlate the posttranscriptional actions of retinoic acid with changes in phosphorylation, or abundance of spliceosome components, or both. Treatment with retinoic acid for periods of < or = 4 h resulted in dephosphorylation of nuclear U1 70K protein without affecting its abundance. Peptide mapping showed that U1 70K dephosphorylation was related to the disappearance of one specific phosphopeptide out of four major U1 70K phosphopeptides. A twofold decrease in mRNA expression of an isoform of alternative splicing factor that inhibits splicing was also observed over the same period. Tumor necrosis factor-alpha, which enhances the posttranscriptional action of retinoic acid, reduced U1 70K mRNA expression, while an inhibition of retinoic acid action by transforming growth factor-beta was associated with a marked increase in U1 70K mRNA levels. Our results draw attention to the complex interactions between short- and long-term alterations in the abundance and functional status of U1 70K, as well as SR proteins by growth and/or differentiation factors in the regulation of spliceosome formation and function.

Cadaver renal transplantation and HLA matching in Australia from 1971 to 1980. A report of the Australian and New Zealand Combined Dialysis and Transplant Registry

The influence of HLA matching on the survival of 2648 cadaver renal grafts carried out in Australian transplant units from January 1971 to October 1980 was analyzed. Survival of grafts well matched for the HLA-A and B antigens was significantly better than that of poorly matched grafts from 1 to 5 years after transplant. The improvement in survival was predominantly attributable to matching for the HLA-B locus antigens, matching for antigens of the HLA-A series contributing only marginally. Although survival of secondary grafts was slightly poorer than that of primary grafts, their survival was improved by HLA matching. No difference in survival on the basis of sex, blood group, or demonstrable presensitization to HLA could be shown, but the influence of HLA matching was greater in males than in females, in group A than group O subjects, and in subjects not sensitized to HLA. In all patient groups, HLA matching based on the number of incompatible antigens carried by the donor had greater prognostic value than matching based on the number of antigens shared by donor and recipient.

Aluminum associated bone disease: clinico-pathologic correlation

A chemical, aurine tricarboxylic acid was used to identify aluminum in bone in a group of chronic renal failure patients with severe osteomalacia. Thirteen out of 49 (26%) patients had a positive stain at the bone-osteoid junction. The presence of aluminum at the staining site was confirmed by electron dispersion x-ray analysis. The patients' biopsies staining negative with this clinical, although having high bone aluminum levels, had more significant features of hyperparathyroidism, both biochemically and histologically than those having a positive stain. The usefulness of this technique to diagnose presymptomatic aluminum related osteomalacia is emphasized.