Evidence for IFN-? up- and IL-4 downregulation late post-transplant in patients with good kidney graft outcome

Cytokine Dynamics and Herpesvirus Interactions in Pediatric Liver and Kidney Transplant Recipients: The Distinct Behavior of HCMV, HHV6, HHV7 and EBV

Pediatric solid organ transplant (SOT) recipients face a challenging balance between immunosuppression and graft rejection. While Epstein-Barr Virus (EBV) and cytomegalovirus (HCMV) are known contributors to post-transplant lymphoproliferative disease and graft rejection, respectively, the roles of herpesvirus 6 and 7 (HHV6 and HHV7) and the impact of these herpesviruses on cytokine levels remain unclear, leading to gaps in clinical practice. In this associative study, we measured 17 cytokines using a Bio-Plex assay in a meticulously curated plasma sample pool (N = 158) from pediatric kidney and liver transplant recipients over a one-year follow-up period. The samples included virus-negative and virus-positive cases, either individually or in combination, along with episodes of graft rejection. We observed that the elevation of IL-4, IL-8, and IL-10 correlated with graft rejection. These cytokines were elevated in samples where HCMV or HHV6 were detected alone or where EBV and HHV7 were co-detected. Interestingly, latent EBV, when detected independently, exhibited an immunomodulatory effect by downregulating cytokine levels. However, in co-detection scenarios with β-herpesviruses, EBV transitioned to a lytic state, also associating with heightened cytokinemia and graft rejection. These findings highlight the complex interactions between the immune response and herpesviruses in transplant recipients. The study advocates for enhanced monitoring of not only EBV and HCMV but also HHV6 and HHV7, providing valuable insights for improved risk assessment and targeted interventions in pediatric SOT recipients.

Acute Versus Chronic Administration of Calcineurin-Inhibitors Differentially Affect T-Cell Function

BACKGROUND

Calcineurin-inhibitors (CNI) are used in renal transplant patients (RTX) to prevent rejection. CNI mainly suppress T-cell mediated immunity but very little is known about the impact of long-term treatment with CNI on T-cell function.

OBJECTIVE

We investigated the immunological effects of long-term CNI intake in RTX patients in comparison to short-term CNI administration in healthy controls (HC).

METHODS

Blood was drawn from 30 RTX patients with long-term CNI treatment. In addition, blood was sampled from HC with short-term CNI treatment (four dosages) before the first and 2 hours after the last CsA intake. T-cells were analyzed for cytokine production, proliferation, and CD25 expression.

RESULTS

Short-term CNI reduced T-cell derived IL-2 and IFNγ as well as T-cell proliferation in HC. IFNγ was not suppressed in patients with long-term CNI treatment. IL-2 production, CD25 expression, and T-cell proliferation were enhanced in long-term CNI patients.

CONCLUSION

Suppression of IFNγ/IL-2 and T-cell proliferation is weaker during long-term CNI treatment in patients compared to short-term treatment in healthy subjects. Enhanced CD25 expression may lower the threshold for T-cell activation during long-term CNI treatment.

Immunogenicity of insulin-producing cells derived from human umbilical cord mesenchymal stem cells

Mesenchymal stem cells (MSCs) have been considered as hypo-immunogenic and immunosuppressive. However, a thorough understanding of the immunological properties after MSC differentiation in vitro and in vivo has not been reached. We asked whether it would be immunogenic after differentiation or influenced by the immune microenvironment after transplantation. In different disease models, the immunological changes of MSCs after differentiation greatly varied, with contradicting results. In order to clarify this, we used a modified four-step induction method to induce human umbilical cord MSCs (hUCMSCs) to differentiate into insulin-producing cells (IPCs), and investigate the immunological changes after differentiation and immune reactions after transplantation into diabetic mice. We found that the induced IPCs are hypo-immunogenic, lacking HLA-DR, CD40 and CD80 expression. Of note, we observed immune cell infiltration to peritoneal cavity and left kidney capsule after local transplantation of induced IPCs. This indicated that hUCMSC-derived IPCs maintained hypo-immunogenic in vitro, but became immunogenic after transplanting to the host, possibly due to the changes of immune microenvironment and thereafter immunological enhancement and immune cell infiltration.

Association Interleukin-4 and Interleukin-4 Receptor Gene Polymorphism and Acute Rejection and Graft Dysfunction After Kidney Transplantation

BACKGROUND

Cytokine genotypes have previously been studied in patients undergoing solid organ transplantation; certain polymorphisms have been implicated in the development of acute rejection (AR) and graft dysfunction (GD). Allograft outcomes determined, in part, by alloimmune responses is mainly mediated by T-cell responses, activated and driven by cytokines. Interleukin-4 (IL-4) is one such cytokine, which exerts its biological effects through binding to the IL-4 receptor (IL-4R) complex on target cells. In the present study, we investigated whether polymorphisms of the IL-4 and/or IL-4R gene were associated with susceptibility to acute AR and GD after kidney transplantation.

METHODS

We analyzed 2 single nucleotide polymorphism (SNPs) of IL-4 (rs2243250 and rs2070874) and 3 SNPs of IL-4R (rs1801275, rs2107356, and rs1805010) in 344 kidney transplant recipients. These patients included 62 of whom had developed AR and 215 of whom had GD in 1 year after kidney transplantation.

RESULTS

The AR group included 62 patients (45 men and 17 women). There was a statistically significant difference in the male-to-female ratio and the use of tacrolimus in the AR group. The GD group included 215 patients. Patients who developed GD were more likely to be older and have an underlying cause of end-stage renal disease that was unknown compared with patients who did not have GD, the cause of which was typically known. Among the SNPs examined, 1 of the SNPs in the IL-4R gene (ie, rs1801275) showed a statistical association with AR (co-dominant model, P = .061; dominant model, P = .019; and log-addictive model, P = .029). In addition, 1 of the IL-4R SNPs (ie, rs2107356) was statistically associated with GD (dominant model, P = .034). No significant difference in the IL-4 genotype was observed between the AR/GD and non-AR/non-GD subjects.

CONCLUSIONS

One IL-4R gene polymorphism (rs1801275) was associated with AR. In addition, a separate IL-4R SNP (rs2107356) was statistically associated with GD after kidney transplantation.

T-cell alloimmunity and chronic allograft dysfunction

Solid organ transplantation is the standard treatment to improve both the quality of life and survival in patients with various end-stage organ diseases. The primary barrier against successful transplantation is recipient alloimmunity and the need to be maintained on immunosuppressive therapies with associated side effects. Despite such treatments in renal transplantation, after death with a functioning graft, chronic allograft dysfunction (CAD) is the most common cause of late allograft loss. Recipient recognition of donor histocompatibility antigens, via direct, indirect, and semidirect pathways, is critically dependent on the antigen-presenting cell (APC) and elicits effector responses dominated by recipient T cells. In allograft rejection, the engagement of recipient and donor cells results in recruitment of T-helper (Th) cells of the Th1 and Th17 lineage to the graft. In cases in which the alloresponse is dominated by regulatory T cells (Tregs), rejection can be prevented and the allograft tolerated with minimum or no immunosuppression. Here, we review the pathways of allorecognition that underlie CAD and the T-cell effector phenotypes elicited as part of the alloresponse. Future therapies including depletion of donor-reactive lymphocytes, costimulation blockade, negative vaccination using dendritic cell subtypes, and Treg therapy are inferred from an understanding of these mechanisms of allograft rejection.

Lymphocyte activation markers may predict the presence of donor specific alloreactivity in pediatric living related liver transplant recipients

This is an observational study with the primary objective to measure donor-specific immune responses by pediatric liver transplant (LT) recipients, using cell surface expression of lymphocyte activation markers and cytokine secretion in mixed lymphocyte reactions. The secondary objective was to demonstrate possible mechanism(s) involved in those who demonstrated donor-specific hyporesponsiveness. Study participants included 17 recipients, their respective parental donors, the non-donor parent, as well as unrelated third party individuals. Within the CD4(+) population, two distinct patterns of CD69 and CD71 expressions were observed: recipients who had a lower percentage of CD4(+)CD69(+) and CD4(+)CD71(+) cells after donor versus non-donor stimulation (therefore a donor/non-donor ratio <1); and recipients who had a higher percentage of CD4(+)CD69(+) and CD4(+)CD71(+) cells after donor versus non-donor stimulation (therefore a donor/non-donor ratio ≥1). Eight recipients had the above defined ratio of <1, with significantly decreased interferon-γ secretion after donor versus non-donor stimulation. CD4(+)CD25(hi.)CD127- regulatory T cells from these eight recipients suppressed donor and non-donor cell induced proliferation. Suppression of proliferation was partially abrogated by interleukin-2. In conclusion, CD69 and CD71 cell surface expression with interferon-γ secretion can be used to identify two distinct populations in pediatric LT recipients. Both active regulation and anergy underlie donor specific hyporesponsiveness.

Donor-specific antibody levels and three generations of crossmatches to predict antibody-mediated rejection in kidney transplantation

BACKGROUND

This study evaluated the prognostic impact of pretransplant donor-specific anti-human leukocyte antigen antibodies (DSA) detected by single-antigen beads and compared the three generations of crossmatch (XM) tests in kidney transplantation.

METHODS

Thirty-seven T-cell complement-dependent cytotoxicity crossmatch (CXM) negative living donor kidney recipients with a retrospectively positive antihuman leukocyte antigen antibody screening assay were included. A single-antigen bead test, a flow cytometry XM, and a Luminex XM (LXM) were retrospectively performed, and the results were correlated with the occurrence of antibody-mediated rejections (AMRs) and graft function.

RESULTS

We found that (1) pretransplant DSA against class I (DSA-I), but not against class II, are predictive for AMR, resulting in a sensitivity of 75% and a specificity of 90% at a level of 900 mean fluorescence intensity (MFI); (2) with increasing strength of DSA-I, the sensitivity for AMR is decreasing to 50% and the specificity is increasing to 100% at 5200 MFI; (3) the LXM for class I, but not for class II, provides a higher accuracy than the flow cytometry XM and the B-cell CXM. The specificity of all XMs is increased greatly in combination with DSA-I values more than or equal to 900 MFI.

CONCLUSIONS

In sensitized recipients, the best prediction of AMR and consecutively reduced graft function is delivered by DSA-I alone at high strength or by DSA-I at low strength in combination with the LXM or CXM.

Role of T cells in graft rejection and transplantation tolerance

Transplantation is the most effective treatment for end-stage organ failure, but organ survival is limited by immune rejection and the side effects of immunosuppressive regimens. T cells are central to the process of transplant rejection through allorecognition of foreign antigens leading to their activation, and the orchestration of an effector response that results in organ damage. Long-term transplant acceptance in the absence of immunosuppressive therapy remains the ultimate goal in the field of transplantation and many studies are exploring potential therapies. One promising cellular therapy is the use of regulatory T cells to induce a state of donor-specific tolerance to the transplant. This article first discusses the role of T cells in transplant rejection, with a focus on the mechanisms of allorecognition and the alloresponse. This is followed by a detailed review of the current progress in the field of regulatory T-cell therapy in transplantation and the translation of this therapy to the clinical setting.

Association of high IFN-gamma plasma levels with low B-cell counts in renal transplant recipients with stable long-term graft function

Recently, we reported that patients with long-term stable good graft function had higher interferon-gamma (IFN-gamma) and lower IL-4 plasma levels late as compared with early post-transplant. These patients had more often detectable CD3(+)CD4(+)CD25(+)IFN-gamma(+)Foxp3(+) peripheral blood lymphocytes (PBL) late post-transplant than patients with impaired graft function. We therefore speculated that high plasma IFN-gamma late post-transplant might contribute to the maintenance of graft acceptance. Using ELISA and four-color flow cytometry, plasma cytokines and PBL subpopulations were measured in 65 renal transplant recipients with stable graft function late post-transplant. High IFN-gamma plasma levels were associated with low CD19(+) B PBL (r = -0.329; p = 0.009) and low activated CD3(+)CD8(+)DR(+) T PBL (r = -0.266; p = 0.035). Plasma IFN-gamma increased with time post-transplant (r = 0.288; p = 0.022) and was not associated with the dose of immunosuppressive drugs (p = n.s.). High plasma IFN-gamma was not associated with serum creatinine (r = 0.038; p = 0.765). Five patients showed evidence of chronic allograft nephropathy in previous biopsies and none of them exhibited increased plasma IFN-gamma. In patients with good long-term graft function, high IFN-gamma plasma levels were associated with low numbers of B PBL and activated CD8(+) T PBL. High IFN-gamma plasma levels might prevent the development of an immunological alloresponse and thereby contribute to the maintenance of graft acceptance.

Granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and other immunomodulatory therapies for the treatment of infectious diseases in solid organ transplant recipients

PURPOSE OF REVIEW

Infections continue to cause significant morbidity and mortality in SOT recipients despite major advances in immunosuppressive and antimicrobial regimens. Immunomodulatory cytokines provide a potential means to augment the host immune response to infection. This review will focus on cytokine therapy for the prophylaxis and treatment of infections in solid organ transplant recipients, and will speculate on the potential for further advances in the field.

RECENT FINDINGS

In kidney and liver transplant recipients, granulocyte colony-stimulating factor (G-CSF) has been used successfully to reverse ganciclovir-induced neutropenia or cytomegalovirus-induced neutropenia. Although G-CSF also reversed corticosteroid-induced suppression of the neutrophil respiratory burst in vitro, prophylactic G-CSF failed to reduce infections or mortality in nonneutropenic solid organ transplant recipients. Published clinical experience with granulocyte-macrophage colony-stimulating factor (GM-CSF) in this population has been limited to case reports and a small case series, whereas the use of macrophage colony-stimulating factor (M-CSF) or interferon-gamma (IFN-gamma) has not been systematically investigated in controlled clinical trials.

SUMMARY

Despite encouraging results in vitro and in preclinical models, immunomodulatory cytokines have not met expectations when administered to SOT recipients. Nonetheless, the principle of selective enhancement of innate immunity for the prevention and treatment of infections in this patient population has promise and warrants further study.

Observational support for an immunoregulatory role of CD3+CD4+CD25+IFN-gamma+ blood lymphocytes in kidney transplant recipients with good long-term graft outcome

There is evidence that interferon-gamma (IFN-gamma)-dependent interactions of dendritic cell (DC), T regulatory (Treg), and T suppressor (Ts) subpopulations contribute to allograft acceptance. We measured DC subsets, CD3+CD4+CD25+ (Treg phenotype) and CD3+CD8+CD28(-) (Ts phenotype) peripheral blood lymphocytes (PBL) expressing Foxp3, Th1 or Th2 cytokines, peripheral T- and B-cell counts, and plasma cytokines in 33 kidney transplant recipients with a serum creatinine of < or =1.8 mg/dl and 32 recipients with a serum creatinine of > or =2.0 mg/dl more than 100 days post-transplant. Cell subsets were measured in whole blood using four-color flow cytometry. Patients with increased creatinine had less frequently detectable CD3+CD4+CD25+IFN-gamma+ PBL than patients with good graft function (P = 0.017). In patients with good graft function, CD3+CD4+CD25+IFN-gamma+ PBL were associated with high Foxp3+, IL-2+, IL-12+, IL-4+, and IL-10+ CD3+CD4+CD25+ T PBL (P < 0.001), low CD3+CD8+CD28(-)Foxp3+ (P = 0.002), CD3+CD4+DR+ (P = 0.002), CD3+CD8+DR+ T (P = 0.005) and CD19+ B PBL (P = 0.005), and low lineage(-)HLA-DR+CD11c+CD123(-) DC1 (P = 0.006). Patients with impaired graft function did not show these associations. Additional flow cytometric analysis confirmed strong co-expression of IFN-gamma and Foxp3 by CD4+CD25+ PBL particularly in patients with good graft function. Our data support an immunoregulatory role of CD3+CD4+CD25+Foxp3+IFN-gamma+ cells in a subgroup of transplant recipients with good graft acceptance.