LF 15-0195 Generates Synergistic Tolerance by Promoting Formation of CD4+CD25+CTLA4+ T Cells

Analysis of cytotoxic T-lymphocyte-associated antigen-4 and MMP-9 genes' methylation and their expression profiles with risk of non-alcoholic fatty liver disease

OBJECTIVE:

To investigate the effect of promoter methylation of cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) gene and matrix metalloproteinases (MMPs) on the risk of non-alcoholic fatty liver disease (NAFLD).

MATERIALS AND METHODS:

CTLA-4 and MMP-9 promoter methylation were investigated using a methylation-specific polymerase chain reaction (MS-PCR) in blood samples taken from 80 NAFLD individuals and 95 healthy controls. The expression levels of CTLA-4 and MMP-9 were also assessed in 10 blood and 9 liver tissues mRNA samples from NAFLD patients. These cases were compared to the blood (n = 10) samples of healthy controls with real-time quantitative reverse transcriptase PCR.

RESULTS:

No significant relationship was found for methylation of CTLA-4 and MMP-9 between cases and controls. The relative expression of CTLA-4 and MMP-9 mRNA in NAFLD was not significantly different compared to healthy control samples.

CONCLUSION:

For the first time, our outcomes indicate that the methylation status of CTLA-4 and MMP-9 genes has no significant function on the process of NAFLD.

Immunosuppression involving soluble CD83 induces tolerogenic dendritic cells that prevent cardiac allograft rejection

BACKGROUND

Dendritic cells (DCs) are crucial regulators of immunity and important in inducing and maintaining tolerance. Here, we investigated the potential of a novel DC-immunomodulating agent, soluble CD83 (sCD83), in inducing transplant tolerance.

METHODS

We used the C3H-to-C57BL/6 mouse cardiac transplantation model that exhibits a combination of severe cell-mediated rejection and moderate antibody-mediated rejection and investigated whether sCD83 could augment a combination therapy consisting of Rapamycin (Rapa) and anti-CD45RB monoclonal antibody (α-CD45) to prolong allograft survival.

RESULTS

Monotherapies consisting of Rapa and α-CD45 were incapable of preventing rejection. However, all treatments involving sCD83 were capable of (1) down-modulating expression of various DC surface molecules, such as major histocompatibility complex class II and costimulatory molecules, (2) reducing the allogeneic stimulatory capacity of the DCs, and (3) significantly inhibiting antidonor antibody responses. Most striking results were observed in the triple therapy-treated group, sCD83Rapaα-CD45, where cell-mediated rejection and antibody-mediated rejection were abrogated for over 100 days. Donor-specific tolerance was achieved in long-term surviving recipients, because donor skin transplants were readily accepted for an additional 100 days, whereas third-party skin grafts were rejected. Success of triple therapy treatment was accompanied by enhancement of tolerogenic-DCs that conferred antigen-specific protection on adoptive transfer to recipients of an allogeneic heart graft.

CONCLUSIONS

Our study revealed that sCD83 is capable of attenuating DC maturation and function, and inducing donor-specific allograft tolerance, in the absence of toxicity. Thus, sCD83 seems to be a safe and valuable counterpart to current DC-modulating agents.

Infusion of mesenchymal stem cells and rapamycin synergize to attenuate alloimmune responses and promote cardiac allograft tolerance

The inherent immunosuppressive properties and low immunogenicity of mesenchymal stems cells (MSCs) suggested their therapeutic potential in transplantation. We investigated whether MSCs could prolong allograft survival. Treatment involving infusion of MSCs into BALB/c recipients 24 hours after receiving a heart allograft from a C57BL/6 donor significantly abated rejection and doubled graft mean survival time compared to untreated recipients. Furthermore, combination therapy of MSCs and low-dose Rapamycin (Rapa) achieved long-term heart graft survival (>100 days) with normal histology. The treated recipients readily accepted donor skin grafts but rejected third-party skin grafts, indicating the establishment of tolerance. Tolerant recipients exhibited neither intragraft nor circulating antidonor antibodies, but demonstrated significantly high frequencies of both tolerogenic dendritic cells (Tol-DCs) and CD4(+)CD25(+)Foxp3(+)T cells in the spleens. Infusion of GFP(+)C57BL/6-MSCs in combination with Rapa revealed that the GFP-MSCs accumulated in the lymphoid organs and grafts of tolerant recipients. Thus, engraftment of infused MSCs within the recipient's lymphoid organs and allograft appeared to be instrumental in the induction of allograft-specific tolerance when administered in combination with a subtherapeutic dose of Rapamycin. This study supports the clinical applicability of MSCs in transplantation.

IL-10 and IL-4 in Skin Allograft Survival Induced by T-Cell Depletion plus Deoxyspergualin

The mechanisms mediating T-cell depletion plus 15-deoxyspergualin (DSG)-induced prolonged allograft survival or tolerance are uncertain. The purpose of this study is to evaluate the role of IL-4 and IL-10 in prolonged allograft survival induced by T-cell depletion plus DSG. MHC mismatched skin allograft transplantation was performed, using wild-type and three separate knockout (i.e., IL-4–/–, Stat6–/-, or IL-10–/–) mice as recipients. Induction therapy consisted of T-cell depletion and or brief course of DSG. The data demonstrate that monotherapy with T-cell-depleting mAbs or DSG prolonged skin allograft survival, compared to controls, in wild-type Balb/c recipients [median survival time (MST) = 25 and 21 vs. 10 days, p < 0.007]. T-cell depletion plus DSG further augmented skin allograft survival in wild-type animals relative to monotherapy (MST = 35 days vs. 25 and 21 days, p < 0.006 vs. mAbs or DSG only), and was equally effective in IL-4–/– and Stat6–/– recipients. In contrast, combined therapy was no better than monotherapy in IL-10–/– animals (p > 0.05). Furthermore, skin allograft survival after combined therapy was shorter in IL-10–/– versus wild-type recipients (MST 20 and 41 days, respectively, p < 0.001). IL-4-mediated signaling through Stat6 is dispensable for prolonged allograft survival induced by T-cell depletion plus DSG. In contrast, IL-10 appears to be important for prolonged allograft survival induced by combined therapy in this model.

Generation of therapeutic dendritic cells and regulatory T cells for preventing allogeneic cardiac graft rejection

Tolerogenic dendritic cells (Tol-DCs) and regulatory T cells (Treg) are key factors in the induction and maintenance of transplantation tolerance. We previously demonstrated that ex vivo-isolated Tol-DCs promote Treg generation, and vice versa, in an in vitro co-culture system. Here we demonstrate the occurrence of such an immune regulatory feedback loop in vivo. Tol-DC generated in vitro by treatment with LF 15-0195 exhibited features of immature DC and express low levels of MHC class II, CD86 and CD40. These Tol-DCs were capable of augmenting CD4(+)CD25(+)CTLA4(+) and FoxP3(+) Treg cell numbers and activity in cardiac allograft recipients. On the other hand, Tol-DCs possessed an ability to generate Treg cells in vitro. The adoptive transfer of these in vitro-generated Treg cells resulted in an increase of Tol-DC in vivo, suggesting that an immune regulatory feedback loop, between Tol-DC and Treg, exists in vivo. Furthermore, the administration of in vitro-generated Tol-DCs or Treg cells prevented rejection of allografts. Co-administration of Tol-DC and Treg synergized efficacy of promoting allograft survival heart transplantation. The present study highlights the therapeutic potential of preventing allograft rejection using in vitro-generated Tol-DCs and Treg.

Antigen-specific therapy of rheumatoid arthritis

BACKGROUND

Immunotherapy offers the promise of antigen-specific suppression of pathological immune responses in conditions such as autoimmunity and organ transplantation. Substantial advances have been made in recent years in terms of understanding basic immunological mechanisms of autoreactivity, as well as clinically implementing immune-based therapies that are antigen nonspecific.

OBJECTIVE

To provide an integrated overview of the current state of the art in terms of antigen-specific tolerance induction, as well as to predict future directions for the field.

METHODS

Examples of successes and failures of antigen-specific immunotherapy were sought. Particular attention was paid to the well-established collagen II-induced model of arthritis.

RESULTS/CONCLUSIONS

Previous failures of antigen-specific immunotherapy were associated with lack of identification of clinically relevant antigens, as well as inappropriate tolerogenic methodologies. The advances in proteomics combined with novel gene-specific immune modulatory techniques place today's translational researchers in a unique position to tackle the problem of antigen-specific immunotherapeutic protocols.