High-level expression of viral interleukin-10 in cardiac allografts fails to prolong graft survival

Regenerative medicine of the kidney

End stage renal disease is a major health problem in this country and worldwide. Although dialysis and kidney transplantation are currently used to treat this condition, kidney regeneration resulting in complete healing would be a desirable alternative. In this review we focus our attention on current therapeutic approaches used clinically to delay the onset of kidney failure. In addition we describe novel approaches, like Tissue Engineering, Stem cell Applications, Gene Therapy, and Renal Replacement Therapy that may one day be possible alternative therapies for patients with the hope of delaying kidney failure or even stopping the progression of renal disease.

Other Transgenic Animal Models Used in Cardiovascular Studies

Previous chapters have described a large number of transgenic animal models used to study specific cardiovascular syndromes. This chapter will fill in some gaps. Many of these transgenic animals were developed to study normal and/or abnormal physiological responses in other organ systems, or to study basic biochemical and molecular reactions or pathways. These models were then discovered to also have effects on the cardiovascular system, some of them unanticipated.

A word of caution, particularly when highly inbred mouse strains are used to develop transgenic models - not all strains of a particular species are created equal. When cardiovascular parameters of age- and sex-matched A/J and C57BL/6J inbred mice were compared the C57BL/6J mice demonstrated eccentric physiologic ventricular hypertrophy, increased ventricular function, lower heart rates, and increased exercise endurance.¹

Viral IL-10 gene transfer prolongs rat islet allograft survival

Islet transplantation is a potential cure for diabetes. However, allotransplant rejection severely limits its clinical application. In this study, we sought to transfect rat islets with an adenoviral vector containing the viral IL-10 (vIL-10) gene and examine its efficacy in preventing graft rejection. The immunosuppressive effect of vIL-10 is reported but its efficacy is somehow debatable in transplantation model. vIL-10 transfected islets were transplanted into streptozotocin-induced diabetic rats. Blood glucose, serum vIL-10 concentration, graft histology, and graft cytokine expression were used to monitor graft function up to day 21 after transplantation. Transfected islets released a large amount of vIL-10 protein without affecting their viability and functional integrity. When we transplanted the transfected islets into allogeneic hosts, the survival of grafted islets was not significantly increased. However, the combined use of vIL-10 and subtherapeutic doses of CsA (cyclosporine) significantly prolonged graft survival beyond that achieved with either agent alone (p < 0.001). vIL-10 and CsA-treated rats contain high level of vIL-10 in serum, which is evidenced by the inhibition of allogeneic mixed lymphocyte reaction (MLR). Histological analysis additionally revealed the presence of viable islets up to 21 days. IL-10 mRNA expression in grafted liver was higher and IFN-gamma mRNA was lower in vIL-10 and CsA-treated animals, compared with other groups. The synergistic effect of this combination therapy is potentially correlated with the induction of inhibitory cytokine secretion and downregulation of proinflammatory cytokine secretion from host cells.

Novel immunosuppression: R348, a JAK3- and Syk-inhibitor attenuates acute cardiac allograft rejection

BACKGROUND

Janus kinase (JAK)3 is crucial for signal transduction downstream of various cytokine receptors in immune cells. This is the first report on the novel JAK3 inhibitor R348.

METHODS

(1) Detailed pharmacokinetic data were obtained in rats; (2) multiple in vitro enzyme inhibition assays were performed to characterize the drug; (3) prevention of acute rejection was investigated in animals treated with different doses of R348 or rapamycin for 5 days; and (4) cardiac allograft survival after a 10-day treatment period was studied for various regimens of R348, tacrolimus, or rapamycin; combination indices were calculated to evaluate drug interactions.

RESULTS

(1) Plasma levels of R348's active metabolite R333 sustained high for 8 hr or more, depending on the dose. (2) In vitro enzyme assays showed potent inhibition of JAK3- and Syk-dependent pathways. (3) R348 40 mg/kg preserved graft function, significantly reduced graft infiltration, and decreased histologic ISHLT rejection scores on postoperative day 5. Results were similar to those of rapamycin 3 mg/kg. Likewise, both drugs significantly reduced the cellular Th1 and Th2 immune responses, as determined by enzyme-linked immunosorbent assays. Intragraft inflammatory cytokine upregulation was similarly suppressed by R348 and rapamycin. R348 10 mg/kg was subtherapeutic. (4) Allograft survival was similar for R348 20 and 40 mg/kg, which was comparable with therapeutically dosed tacrolimus or rapamycin. In combination regimens, R348 demonstrated highly beneficial synergistic interactions with tacrolimus.

CONCLUSIONS

R348 is a promising novel JAK3/Syk-inhibitor with favorable pharmacokinetics and biological activity. It effectively diminishes acute cardiac allograft rejection and is suitable for combination regimens with tacrolimus.

IL-10 inhibits endothelium-dependent T cell costimulation by up-regulation of ILT3/4 in human vascular endothelial cells

Effects of IL-10 on endothelium-dependent T cell activation have not been investigated in detail. We confirm expression of the IL-10 receptor and effective signaling via STAT-3 in human umbilical vein endothelial cells (HUVEC). In CD4 T cell cocultures with HUVEC, pretreatment of endothelial cells with IL-10 resulted in significant dose-dependent inhibition of CD4 T cell proliferation, which also occurred when IL-10 was removed after pretreatment before starting cocultures. Th1/Th2 polarization of proliferated T cells, endothelial nitric oxide (NO), or IL-12 production were unchanged. However, IL-10 stimulation resulted in up-regulation of SOCS-3, a negative regulator of cytokine secretion, and induction of the inhibitory surface molecules immunoglobulin-like transcript 3 and 4 (ILT3/ILT4) in EC, potentially involving glucocorticoid-induced leucine zipper (GILZ). Addition of blocking antibodies against ILT3/ILT4 to EC/T cell cocultures resulted in nearly complete reestablishment of T cell proliferation. In contrast, addition of soluble ILT3 or overexpression of ILT3 in cocultures significantly reduced T cell proliferation. No induction of foxp3+ regulatory T cells was seen. In conclusion, the T cell costimulatory potential of human EC is markedly suppressed by IL-10 due to up-regulation of ILT3/ILT4, obviously not involving generation of Treg. This identifies a novel action of IL-10 in EC and a potential therapeutical target for local immunomodulation.

Autoreactivity to self H-2Kb peptides in TAP1 mice. Intravenous administration of H-2Kb class I-derived peptides induces long-term survival of grafts from C57BL/6 donors

We and others have previously shown that TAP1-/- mice (H-2b) reject grafts from donors without major histocompatibility complex (MHC) disparity that express wild-type levels of H-2b class I molecules (C57BL/6, TAP1+/+ mice). In this same model, we also showed that subcutaneous priming of TAP1-/- mice with synthetic peptides derived from the H-2Kb molecule accelerated graft rejection and that in vivo depletion of CD4+ T cells induced a significant prolongation of graft survival, suggesting an important role for CD4 T cells. We hypothesize that, in this model, rejection is triggered by the recognition of class I molecules or derived peptides, in an inflammatory microenvironment, by a functionally altered autoreactive T-cell repertoire that escapes the control of peripheral regulatory mechanisms. In the present study, we analysed the cellular autoreactivity induced by synthetic peptides derived from the H-2Kb sequence in naive and TAP1-/- mice transplanted with C57BL/6 grafts, and investigated whether intravenous modulation of autoreactivity to these peptides induced transplantation tolerance. We showed that TAP1-/- mice have peripheral autoreactive T cells that recognize H-2Kb peptides. A significant amplification of proliferation against these peptides was detected in TAP1-/- mice that rejected grafts, indicating that the inflammatory context of transplantation induced peripheral expansion of these autoreactive T cells. Furthermore, intravenous injection of H-2Kb-derived peptides significantly prolonged graft survival in some animals. In these mice (> 100 days graft survival), we observed intragraft inhibition of interferon-gamma and interleukin-10 expression, suggesting that these cytokines have an active role during the rejection. In conclusion, our present data indicate that inflammatory autoreactive T cells directed against H-2Kb peptides can be inhibited in the periphery to prolong graft survival in TAP1-/- mice.

Graft coronary artery disease in murine cardiac allografts: proposal to meet the need for standardized assessment

BACKGROUND

Inconsistency exists in assessing the severity of graft coronary artery disease (GCAD) in studies that use mouse models. The central issue associated with this inconsistency is the lack of a standardized approach for assessing mouse GCAD.

METHODS

We propose a new histologic definition of GCAD based on 3 successive stages (endotheliitis, premature lesion, and mature lesion) that mark the progression of this condition. In addition to these qualitative measures of GCAD, we propose including 2 additional morphometric parameters (percentage of luminal narrowing and intima-to-media ratio) and a measure of distribution (percentage of affected vessels) in the routine quantification of GCAD.

RESULTS

We introduce 2 new mouse models of GCAD as examples that satisfy these criteria.

CONCLUSION

The proposed assessment criteria may simplify data collection and interpretation of results in various models of GCAD.

Unexpected effects of viral interleukin-10-secreting dendritic cells in vivo: preferential inhibition of TH2 responses

Viral interleukin (IL)-10 (vIL-10) has been widely described as an immunoregulatory cytokine that does not possess the T-cell costimulatory activities of cellular IL-10; it was therefore believed to be a more potent tolerogenic mediator. The immunosuppressive properties of this cytokine are partly attributed to its capacity to render dendritic cells (DCs) unable to undergo full maturation and to activate T cells. We reported here that myeloid DCs retrovirally transduced with vIL-10 had an impaired production of IL-12 and a decreased expression of MHC class II molecules but had minor defects in costimulatory molecule expression and no alteration on CCR5 and CCR7 expression. In mixed leukocyte reaction, vIL-10-transduced C57BL/6 bm12 (MHC class II mismatch) DCs had a reduced capacity to stimulate C57BL/6 wild-type CD4+ T-cell proliferation. We show that bm12 vIL-10-transduced DC administration in CD8-/- C57BL/6 mice promoted IFN-gamma production, down-regulated TH2-type cytokine production, and did not induce skin graft tolerance. These findings suggest that vIL-10-transduced DC may surprisingly facilitate Th1-type inflammatory responses in vivo.

Viral interleukin-10-engineered autologous hematopoietic stem cell therapy: a novel gene therapy approach to prevent graft rejection

The Epstein-Barr virus-encoded protein BCRF1 (viral interleukin [vIL]-10) is a biologically active homologue of cellular interleukin (IL)-10. In this study, a novel gene therapy approach to prolong allograft survival was designed. Autologous (syngeneic) hematopoietic progenitor/stem cell-enriched (HSC; lineage(-ve)) population derived from CBA/J mouse bone marrow were transduced with retrovirus encoding vIL-10 gene (vIL-10-HSC), ex vivo; vIL-10-HSC were injected (4-6 x 10(6) cells intravenously) into lethally (9.5 Gy) or sublethally (4 Gy) irradiated CBA/J mice. Six weeks after vIL-10-HSC administration, vascular heterotopic heart (C57BL/6) transplantation was performed. Ex vivo, the vIL-10-HSC produced 5.4 +/- 0.5 ng of vIL-10 protein/2 x 10(5) cells per 24 hr. In vivo, serum vIL-10 production was 187 +/- 205 pg/ml during 3-10 weeks after vIL-10-HSC administration. Cardiac allograft survival was prolonged (p < 0.004) in lethally (71 +/- 40 days) and sublethally (114 +/- 15 days) irradiated mice that received vIL-10-HSC compared to controls that received unengineered (UE) HSC or vector DNA-engineered HSC (12-16 days). However, secondary skin graft (C57BL/6) survival was not prolonged in cardiac allograft-tolerant animals. In the vIL-10-HSC-administered group, graft histopathology demonstrated mild arteritis/venulitis (grade 0.7) and rejection (grade 1.0). Intragraft expression of costimulatory molecules (B7.1, B7.2), cytokines (IL-2, IL-4, mIL-10, interferon [IFN]-gamma), and inducible nitric oxide synthase (iNOS) molecules was markedly lower in vIL-10-HSC-treated tolerant grafts that survived more than 100 days compared to vector DNA-HSC- or UE-HSC-treated controls. Furthermore, T lymphocytes derived from vIL-10-HSC-treated tolerant recipients demonstrated hyporeactivity to donor antigens in mixed lymphocyte cultures. Administration of autologous vIL-10-engineered HSC prior to organ transplantation prolonged cardiac allograft survival significantly.

Secreted Immunomodulatory Viral Proteins as Novel Biotherapeutics

Many viruses have learned to evade or subvert the host antiviral immune responses by encoding and expressing immunomodulatory proteins that protect the virus from attack by elements of the innate and acquired immune systems. Some of these viral anti-immune regulators are expressed as secreted proteins that engage specific host immune targets in the extracellular environment, where they exhibit potent anti-immune properties. We review here viral immunomodulatory proteins that have been tested as anti-inflammatory reagents in animal models of disease caused by excessive inflammation or hyperactivated immune pathways. The potential for such viral molecules for the development of novel drugs to treat immune-based or inflammatory disorders is discussed.

Viral interleukin-10 gene therapy to induce tolerance to solid organ transplants in mice

In this study, a novel gene therapy approach to prolong allograft survival was designed. Autologous (syngeneic) hematopoietic stem cell-enriched bone marrow cells (HSC; lin(-)) engineered with the vIL-10 gene (vIL-10-HSC) were injected (4 to 6 x 10(6) cells, i.v.) into lethally (9.5 Gy) or sublethally (4 Gy) irradiated CBA/J mice 6 weeks prior to allogeneic heart (C57BL/6) transplantation (Tx). Cardiac allograft survival was significantly (P <.004) prolonged in lethally (71 +/- 40 days) and sublethally (114 +/- 15 days) irradiated mice that received vIL-10-HSC compared to controls that received no HSC (11 +/- 1 days), unengineered HSC, or vector-DNA-engineered HSC (12 to 16 days). Tolerant graft histopathology demonstrated mild arteritis/venulitis (grade 0.7) and rejection (grade 1.0). Intragraft expression of costimulatory molecules (B7.1, B7.2), cytokines (IL-2, IL-4, mIL-10, IFN-gamma), and iNOS molecules were markedly lower in tolerant grafts that survived for >100 days; recipient T lymphocytes demonstrated hyporeactivity to donor and third-party antigens in mixed lymphocyte cultures. These findings have important implications and potential therapeutic applications in transplantation and autoimmune diseases.