Successful suppression of the early rejection of pig islets in monkeys

Primary nonfunction (PNF) is seen very frequently after xenogeneic transplantation of islets of Langerhans. In a pig-to-rat model we recently observed that no PNF occurs when the islets are kept in culture at 37 degrees C for 1-2 weeks prior to transplantation. In order to investigate the rejection mechanisms in a preclinical model, we transplanted cultured porcine islets under the capsule of both kidneys in four cynomolgous monkeys. Islets were isolated from adult sows by means of digestion with Liberase in University of Wisconsin solution (UWS). The digest was purified by a density gradient of OptiPrep in UWS. Highly purified (>95%) islets were cultured 1-2 weeks in RPMI. All monkeys showed significant titers of preformed anti-pig antibodies. The immunosuppression of the monkeys consisted of cyclophosphamide (Cy) (2 days), cyclosporin A (CsA), and prednisolone. Anticipating a fast rejection we carried out nephrectomies at different time points within 2 weeks after transplantation. Following unilateral nephrectomy, well-preserved islets with no signs of rejection were observed between 3 and 7 days posttransplant. Later, between days 11 and 15 posttransplant, histology in the first three animals demonstrated no islets. In the fourth monkey histology on day 11 showed islets with excellent morphology and some small focal infiltrates. The highest CsA blood levels (around 1000 ng/ml) were found in animals with the best graft survival. We conclude that cultured porcine islets can be grafted without hyperacute rejection in monkeys with preformed anti-pig antibodies. In the presence of high levels of CsA only marginal signs of a cellular immune response were observed 11 days after transplantation.

Oral efficacy of the macrolide immunosuppressant SDZ RAD and of cyclosporine microemulsion in cynomolgus monkey kidney allotransplantation

BACKGROUND

40-O-(2-Hydroxyethyl)-rapamycin (SDZ RAD) is a novel, potent, macrolide immunosuppressant. Its efficacy in rodent transplantation models provided the rationale for us to evaluate the compound in a more relevant, large animal transplantation model.

METHODS

Life-supporting kidney allotransplantation was performed in cynomolgus monkeys: rejection was inferred from a rise in serum creatinine or urea and was subsequently confirmed by histopathology. This model was validated with the microemulsion formulation of cyclosporine (i.e., Neoral). Two studies with a microemulsion formulation of SDZ RAD were performed. First, in a dose-finding study, the SDZ RAD dose was reduced in a stepwise fashion until rejection occurred, either with SDZ RAD as monotherapy, or in combination with a fixed, suboptimal dose of cyclosporine. Second, an efficacy study was performed in which two fixed SDZ RAD doses (0.75 and 1.50 mg/kg/ day) were evaluated in monotherapy and compared with the same doses of rapamycin (sirolimus). All immunosuppressants were administered once daily by gastric gavage.

RESULTS

Untreated control animals rejected their grafts between 4 and 8 days after transplantation. Cyclosporine (initially at 150 mg/kg/day, reduced to 100 mg/kg/day 2 weeks after transplantation) yielded long-term (>100 days) rejection-free allograft survival in four of five animals. A 10 mg/kg/day dose of cyclosporine led to rejection between 10 and 27 days after transplantation and was considered suboptimal. In the dose-finding study with SDZ RAD monotherapy, rejection occurred in most of the cases (four of six animals) when a dose level of 0.63 mg/kg/day had been reached. Combined with suboptimal cyclosporine, this threshold SDZ RAD dose was about 2-fold lower. In the efficacy study, median graft survival with histologically proven rejection was 32 days (range 8-91 days, n=6) for 0.75 mg(kg/day SDZ RAD and 59 days (range 28-85 days, n=6) for 1.50 mg/kg/day SDZ RAD. For sirolimus, median graft survival was 43 days (range 5-103 days, n=7) for the 0.75 mg/kg/day dose and 56 days (range 8-103 days, n=8) for the 1.50 mg/kg/day dose. There was no statistically significant difference in efficacy between SDZ RAD and sirolimus.

CONCLUSION

SDZ RAD, in the absence of any other immunosuppressant and at doses that do not show any overt toxicity, considerably prolongs rejection-free survival of cynomolgus monkeys after life-supporting kidney allotransplantation.

Prevention of renal allograft rejection in primates by blocking the B7/CD28 pathway

BACKGROUND

There is accumulating evidence that blockade of the costimulatory pathways offers a valid approach for immune suppression after solid organ transplantation. In this study, the efficacy of anti-CD80 and anti-CD86 monoclonal antibodies (mAbs) in combination with cyclosporine (CsA) to prevent renal allograft rejection was tested in non-human primates.

METHODS

Rhesus monkeys were transplanted with a partly major histocompatibility complex-matched kidney on day 0. Anti-CD80 and anti-CD86 mAbs were administered intravenously daily for 14 days starting at day - 1. CsA was given intramuscularly for 35 days starting just after transplantation. The kidney function was monitored by determining serum creatinine levels.

RESULTS

The combination of anti-CD80 and anti-CD86 mAbs completely abrogated the mixed lymphocyte reaction. Untreated rhesus monkeys rejected the kidney allograft in 5-7 days. Treatment with anti-CD80 plus anti-CD86 mAbs resulted in a significantly prolonged graft survival of 28+ 7 days (P=0.025). There were no clinical signs of side effects or rejection during treatment. Kidney graft rejection started after the antibody therapy was stopped. The anti-mouse antibody response was delayed from day 10 to 30 after the first injection. No difference in graft survival was observed between animals treated with CsA alone or in combination with anti-CD80 and anti-CD86 mAbs. However, treatment with anti-CD80 and anti-CD86 mAbs reduced development of vascular rejection.

CONCLUSIONS

In combination, anti-CD80 and antiCD86 mAbs abrogate T-cell proliferation in vitro, delay the anti-mouse antibody response in vivo, and prevent graft rejection and development of graft vascular disease in a preclinical vascularized transplant model in non-human primates.

Prolonged skin graft survival by administration of anti-CD80 monoclonal antibody with cyclosporin A

Costimulation via the B7/CD28 pathway is an important signal for the activation of T cells. Maximal inhibition of T-cell activation and the induction of alloantigen-specific nonresponsiveness in vitro was achieved using anti-CD80 monoclonal antibody (mAb) in combination with cyclosporin A (CsA). Based on this knowledge, the efficacy of the prophylactic treatment of anti-CD80 mAb and CsA on allogeneic skin graft survival was tested in a preclinical rhesus monkey model. No side effects have been observed. Administration of anti-CD80 mAb resulted in high mAb serum levels that decreased to undetectable values around day 7. At the same time, the anti-mouse antibody response started to develop. The anti-CD80 mAb bound to peripheral blood mononuclear cells and was detectable in lymph node and grafted skin during the treatment period. The skin graft survival time of untreated or suboptimally CsA-treated rhesus monkeys was 10 days. Treatment with CsA (blood levels of 100-160 ng/ml) in combination with anti-CD80 mAb (0.5 mg/kg) resulted in a significantly increased skin graft survival time to 14 days. Eventually, skin grafts in all rhesus monkeys were rejected, which coincided with an increase in helper and cytotoxic T-cell frequency and induction of an antibody response directed against the donor antigens. Therefore, treatment of anti-CD80 mAb in combination with CsA has significant immunosuppressive potency, but was unable to induce donor-specific nonresponsiveness in skin graft recipients.

The effects of interferon beta treatment on arthritis

OBJECTIVE

To determine whether interferon beta (IFN-beta) therapy might have a beneficial effect on arthritis, we evaluated the effect of IFN-beta on collagen type II-induced arthritis (CIA) in rhesus monkeys and conducted a pilot study in patients with rheumatoid arthritis (RA).

METHODS

Four rhesus monkeys with CIA were treated with 10 x 10(6) U (MIU)/kg mammalian cell-derived recombinant IFN-beta (Rebif; Ares-Serono) s.c. daily for 1 week. Subsequently, 12 patients with active RA were treated for 12 weeks with purified natural fibroblast IFN-beta (Frone, Ares-Serono) s.c. 3 times weekly at the following dosages: 6 MIU (n = 4), 12 MIU (n = 4) and 18 MIU (n = 4).

RESULTS

Rapid clinical improvement during IFN-beta therapy was observed in three of the four rhesus monkeys with CIA. There was also a marked decrease in serum C-reactive protein (CRP) levels with a subsequent increase after discontinuation of the treatment in all monkeys. The 10 RA patients who completed the study exhibited on average gradual improvement of tender and swollen joint counts, patient's assessment of pain, and patient's and doctor's global assessment (all P < 0.05). The health assessment questionnaire and serum CRP levels also tended to decrease, but this was not statistically significant; 40% of the patients fulfilled the ACR criteria for 20%, improvement, whereas none fulfilled the ACR criteria for 50% improvement 12 weeks after initiation of treatment. There was no clear dose response relationship.

CONCLUSION

The data suggest that IFN-beta treatment has a beneficial effect on arthritis.

Caddisflies (Trichoptera: Hydropsychidae) used for evaluating water quality of large European rivers

In many European rivers, biodiversity has declined dramatically, and especially riverine insects have disappeared during the past decades. It remains unclear whether poor water quality or deteriorated habitats are limiting the distribution of sensitive aquatic insects in these rivers. The aim of this study, therefore, was to find out if water quality alone is limiting the distribution of these insects in rivers that have suffered from anthropogenic disturbances. To this purpose, caddisflies of the genus Hydropsyche, which are representative riverine insect species, were incubated in two large European rivers, the Rhine and the Meuse. Survival of caddisflies in the River Rhine was fairly high, while there was almost no survival in the River Meuse in three out of five field experiments. The incubations of Hydropsyche in the River Meuse provide evidence that even adequate structural habitat would be insufficient for the reestablishment of Hydropsyche species. The factors limiting the distribution of Hydropsyche species change with the changing constitution of the water; there is not one (group of) compound(s) responsible for the poor water quality. Besides chemical factors, physical factors (like oxygen and current velocity) may be limiting in the River Meuse for Hydropsyche species.

Complete withdrawal of immunosuppression in kidney allograft recipients: a prospective study in rhesus monkeys

BACKGROUND

We previously reported the successful withdrawal of immunosuppression in kidney-allografted rhesus monkeys. Recipients had received pretransplant blood transfusions and cyclosporine (CsA) immunosuppression for 6 to 12 months. One animal is still alive at more than 15 years after transplantation. Our hypothesis was that the sharing of a single DR antigen between blood donor and recipient, and the sharing of the same DR antigen with the kidney donor, may be beneficial to allograft survival. We now report on the results from a prospective study.

METHODS

The animals received three pretransplant blood transfusions from a single donor sharing one DR antigen with the recipient. Subsequently, a life-supporting kidney from a donor sharing the same DR antigen was transplanted. CsA was given for at least 6 months after transplantation.

RESULTS

Two animals rejected their graft at 5-8 weeks after cessation of CsA treatment. One animal is still alive at 700 days after transplantation. This animal showed MLR nonreactivity to its kidney donor, similar to the animal at more than 15 years after transplantation.

CONCLUSION

These results demonstrate that withdrawal of immunosuppression may be a realistic option in kidney graft patients under careful immunological monitoring of donor-specific immunity.

Asymptomatic synovitis precedes clinically manifest arthritis

OBJECTIVE

It has been hypothesized that asymptomatic synovitis may precede clinical manifestations of arthritis in the earliest phase of rheumatoid arthritis (RA). To obtain more insight into this disease phase, we investigated the immunohistologic features of synovial tissue (ST) from the knee joints of rhesus monkeys with induced arthritis and from RA patients with both clinically involved and clinically uninvolved knee joints.

METHODS

Serial ST biopsy specimens from the knee joints of 4 rhesus monkeys that had been immunized with type II collagen and ST from 10 RA patients were investigated. Eight patients without inflammatory joint disease served as controls.

RESULTS

In ST from immunized monkeys, an influx of macrophages was observed well before the occurrence of arthritis. Signs of inflammation were also demonstrated in ST from clinically uninvolved knee joints of all RA patients evaluated. The ST was characterized in particular by infiltration with macrophages and by the expression of macrophage-derived cytokines.

CONCLUSION

The findings support the view that asymptomatic synovitis precedes clinically manifest arthritis in both early and established RA. This implies that the debut of RA already represents a chronic phase of the disease.

Characterization of the ABO blood group genes in macaques: evidence for convergent evolution

The ABO blood group system is known to act as a major transplantation barrier in primates. Different primate species share the presence of A and B antigens. The polymorphism of the macaque ABO blood group genes was analyzed by cloning and sequencing the exon 7 region. In the case of the rhesus macaque (Macaca mulatta) and cynomolgus monkey (Macaca fascicularis) we were able to identify ABO blood group gene segments which cluster into two lineages, namely: *A/*O1 and *B. In addition allelic variation was observed. The 2 amino acid replacements at positions 266 and 268, which are thought to be crucial for A or B transferase activity, could be confirmed for both macaque species. Comparison of primate sequences shows that A and B reactivity was generated independently from each other in the hominoids and Old World monkey lineages. Hence, the primate A and B blood group genes are subject to convergent evolution.

Collagen-induced arthritis in rhesus monkeys: evaluation of markers for inflammation and joint degradation

The objective of this study was to analyse parameters in rhesus monkey collagen-induced arthritis (CIA) with which the inflammation and destruction of the joints can be described in quantitative terms. CIA was induced in genetically susceptible and resistant monkeys, which can be distinguished on the basis of the dominant resistance marker Mamu-A26. The disease course was monitored daily using a semiquantitative scoring system. Plasma samples were collected once or twice weekly and analysed for C-reactive protein (CRP). Urines were collected overnight once a week and analysed for excretion rates of the collagen cross-links hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP). The results show that periods of active CIA are characterized by substantial weight loss and increased plasma CRP levels, followed shortly thereafter by increased excretion rates of the collagen cross-links HP and LP. Remission of the disease can be recognized by a decline in plasma CRP levels and especially an increase in body weight. The highest CRP levels were found in the most severely arthritic monkeys, indicating a possible relationship of the absolute plasma CRP levels to the severity of inflammation. During periods of active arthritis, increased excretion rates of collagen cross-links HP and LP in the urine were found. In particular, the major collagen cross-link in articular cartilage, HP, showed a strong increase (9- to 15-fold). The excretion rates of LP, which is considered as a bone-specific degradation marker, only increased 4- to 6-fold, thus indicating predominant destruction of cartilage and less of bone. In conclusion, the severity of CIA can be monitored in a quantitative manner using plasma CRP levels, urinary excretion rates of HP and LP, and body weights, superimposed on semiquantitative clinical scores. The parameters also facilitate a more objective assessment of the effect of anti-arthritic drugs in the model than with the clinical scores alone.

Flow cytometric analysis on reactivity of human T lymphocyte-specific and cytokine-receptor-specific antibodies with peripheral blood mononuclear cells of chimpanzee (Pan troglodytes), rhesus macaque (Macaca mulatta), and squirrel monkey (Saimiri sciureus)

There are relatively few monoclonal antibodies (mAb) that have been characterized for their applicability in studies on the immune system of various nonhuman primates. In the present study, we identified a large number of mAb that can be used in future immunological studies in three different nonhuman primates, i.e., chimpanzees, rhesus macaques, and squirrel monkeys. The reactivity of 161 anti-human mAb to T-cell antigens and cytokine receptors were tested on peripheral blood mononuclear cells (PBMC) from the three primate species by flow cytometric analysis. A total of 105 (65%), 73 (45%), and 68 (42%) antibodies reacted with PBMC from chimpanzees, rhesus macaques, and squirrel monkeys, respectively. Out of the 161 mAb, 38 reacted with all three species and 112 reacted with one or two of the species. No specific reaction was observed with mAb to receptors to GM-CSF, 4-1BB, FLT3, FLX2, common beta-chain, IL-1 (type I receptor), and IL-8.

Encephalitogenic potential of myelin basic protein-specific T cells isolated from normal rhesus macaques

Myelin basic protein (MBP)-specific T cells are implicated in the pathogenesis of multiple sclerosis and are targets of selective immunotherapies. However, autoantigen-specific T cells can also be isolated from healthy individuals. Their functional potential is unknown and obviously cannot be tested in humans. We approached this question in a closely related primate species, the rhesus monkey. CD4+ T cell lines specific for MBP were isolated from normal rhesus monkeys using the same primary limiting dilution technique that is now widely used to generate human autoreactive T cell clones in vitro. Three different epitopes were recognized by three rhesus T cell lines isolated from three different monkeys. Upon activation, all lines produced interferon-gamma, interleukin-2, tumor necrosis factor-alpha, and granulocyte/macrophage colony-stimulating factor but neither interleukin-4 nor transforming growth factor-beta. The MBP-specific T cells were injected intravenously without adjuvant into the nonirradiated autologous monkey. One of the three rhesus monkeys developed an encephalomyelitis with a pleocytosis in the spinal fluid and perivascular infiltrates in the leptomeninges, spinal nerve roots and cerebral cortex. The data demonstrate that the normal immune repertoire of a primate species contains MBP-specific CD4+ T cells that are able to induce an autoimmune encephalomyelitis upon transfer into the nonirradiated autologous recipient.