Elevated hemoglobin levels in renal transplant recipients with polycystic kidney disease versus other etiologies: exploring mechanisms and implications for outcomes.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD)-related end-stage kidney disease (ESKD) often necessitates transplantation. However, the impact of ADPKD on post-transplant outcomes, specifically hemoglobin levels, remains unknown. METHODS: We retrospectively analyzed 513 Kidney Transplant Recipients (KTRs), of whom 81 had ESKD due to ADPKD (20 with pre-transplant native nephrectomy and 61 without). Hemoglobin levels were evaluated at multiple time intervals post-transplant. RESULTS: Kidney transplant recipients with ADPKD vs. KTRs with ESKD due to other causes exhibited significantly higher hemoglobin levels in repeated measurement analysis. Multivariable analyses confirmed ADPKD as an independent predictor for elevated hemoglobin levels. In a multivariable logistic regression analysis, the odds for maximum hemoglobin > 15 mg/dL at 3-12 months post-transplant were more than twice as high in ADPKD patients vs. all the other KTRs (Odds Ratio [OR] 2.31, 95% Confidence Interval [CI] 1.3-4.13, p < 0.001). Pre-transplant native nephrectomy revealed a trend toward lower hemoglobin levels. Elevated hemoglobin levels were linked to improved estimated glomerular filtration rate (eGFR) at one year post-transplant. Patient survival was enhanced among KTRs with ADPKD compared to other ESKD causes. CONCLUSIONS: Kidney transplant recipients with ADPKD exhibited elevated hemoglobin levels post-transplant, possibly due to prolonged native kidney erythropoietin production. These elevated hemoglobin levels were linked to improved outcomes, including allograft function and patient survival. Future research should further investigate the underlying mechanisms driving favorable ADPKD KTR outcomes.

Assessing Health-Related Quality of Life in Non-Directed Versus Directed Kidney Donors: Implications for the Promotion of Non-Directed Donation.

Living kidney donation has increased significantly, but little is known about the post-donation health-related quality of life (HRQoL) of non-directed donors (NDs) vs. directed donors (DDs). We thus examined the outcomes of 112 living kidney donors (82 NDs, 30 DDs). For the primary outcomes-namely, the mean physical component summary (PCS) and mental component summary (MCS) scores of the 12-item Short Form Survey (SF-12) questionnaire-scores were significantly higher for the NDs vs. the DDs (PCS: +2.69, MCS: +4.43). For secondary outcomes, NDs had shorter hospital stays (3.4 vs. 4.4 days), returned to physical activity earlier (45 vs. 60 days), exercised more before and after donation, and continued physical activity post-donation. Regression analyses revealed that donor type and white blood cell count were predictive of the PCS-12 score, and donor type was predictive of the MCS-12 score. Non-directed donation was predictive of a shorter hospital stay (by 0.78 days, p < 0.001) and the odds of having PCS-12 and MCS-12 scores above 50 were almost 10 and 16 times higher for NDs, respectively (p < 0.05). These findings indicate the safety and potential benefits of promoting non-directed donation. However, careful selection processes must be maintained to prevent harm and exploitation.

Is autoimmune diabetes caused by aberrant immune activity or defective suppression of physiological self-reactivity?

Two competing hypotheses are proposed to cause autoimmunity: evasion of a sporadic self-reactive clone from immune surveillance and ineffective suppression of autoreactive clones that arise physiologically. We question the relevance of these hypotheses to the study of type 1 diabetes, where autoreactivity may accompany the cycles of physiological adjustment of ß-cell mass to body weight and nutrition. Experimental evidence presents variable and conflicting data concerning the activities of both effector and regulatory T cells, arguing in favor and against: quantitative dominance and deficit, aberrant reactivity and expansion, sensitivity to negative regulation and apoptosis. The presence of autoantibodies in umbilical cord blood of healthy subjects and low incidence of the disease following early induction suggest that suppression of self-reactivity is the major determinant factor.

Depletion of naïve lymphocytes with fas ligand ex vivo prevents graft-versus-host disease without impairing T cell support of engraftment or graft-versus-tumor activity.

Graft-versus-host disease (GVHD) can be prevented by Fas-mediated selective depletion of host-sensitized donor lymphocytes ex vivo. We tested the hypothesis that Fas-mediated depletion of lymphocytes in the absence of host-specific antigenic stimulation can alleviate GVHD. Brief exposure (24 hours) of unstimulated donor lymphocytes to Fas ligand (FasL) ex vivo results in balanced apoptosis of CD8(+) and CD4(+) subsets with preferential depletion of CD62L and CD69, increased T regulatory fractions, and sustained responses to stimulation. This procedure ameliorates weight loss and improves the clinical and histologic score of skin and gastrointestinal GVHD with and without concurrent transplantation of hematopoietic progenitors and irrespective of conditioning-induced tissue injury. Although FasL-resistant donor T cells are less potent effectors of GVHD, they facilitate hematopoietic progenitor engraftment when infused with or after the graft and retain the potential to elaborate graft-versus-tumor reactions. These findings in a preclinical model together with the known trophic effects of FasL on primitive hematopoietic progenitors suggest that brief ex vivo incubation of hematopoietic grafts with FasL may improve the outcome and safety of clinical T cell-replete allogeneic and haploidentical transplants.

Effector and naturally occurring regulatory T cells display no abnormalities in activation induced cell death in NOD mice.

BACKGROUND: Disturbed peripheral negative regulation might contribute to evolution of autoimmune insulitis in type 1 diabetes. This study evaluates the sensitivity of naïve/effector (Teff) and regulatory T cells (Treg) to activation-induced cell death mediated by Fas cross-linking in NOD and wild-type mice. PRINCIPAL FINDINGS: Both effector (CD25(-), FoxP3(-)) and suppressor (CD25(+), FoxP3(+)) CD4(+) T cells are negatively regulated by Fas cross-linking in mixed splenocyte populations of NOD, wild type mice and FoxP3-GFP trangeneess. Proliferation rates and sensitivity to Fas cross-linking are dissociated in Treg cells: fast cycling induced by IL-2 and CD3/CD28 stimulation improve Treg resistance to Fas-ligand (FasL) in both strains. The effector and suppressor CD4(+) subsets display balanced sensitivity to negative regulation under baseline conditions, IL-2 and CD3/CD28 stimulation, indicating that stimulation does not perturb immune homeostasis in NOD mice. Effective autocrine apoptosis of diabetogenic cells was evident from delayed onset and reduced incidence of adoptive disease transfer into NOD.SCID by CD4(+)CD25(-) T cells decorated with FasL protein. Treg resistant to Fas-mediated apoptosis retain suppressive activity in vitro. The only detectable differential response was reduced Teff proliferation and upregulation of CD25 following CD3-activation in NOD mice. CONCLUSION: These data document negative regulation of effector and suppressor cells by Fas cross-linking and dissociation between sensitivity to apoptosis and proliferation in stimulated Treg. There is no evidence that perturbed AICD in NOD mice initiates or promotes autoimmune insulitis.

Does lymphopenia preclude restoration of immune homeostasis? The particular case of type 1 diabetes.

Induction of hematopoietic chimerism initiates tolerizing processes that often restore control over autoimmune reactions: graft versus autoimmunity reaction. In view of the limited capacity of autologous bone marrow transplants and some cases of persistent autoimmune diabetes after allogeneic transplants, we hypothesize that the preparative conditioning regimens adopted from the oncological setting are suboptimal approaches to rebooting the immune system. In general, homeostatic expansion under lymphopenic conditions favors the recovery and development of cytotoxic T cells. Autoimmune diabetes is a particular case in which debulking is ineffective due to resistance of the effector cells to depletion by conventional immunosuppressive therapies. Furthermore, resetting of immune activity is impaired by lymphopenia-induced proliferation of residual diabetogenic clones and delayed recovery of suppressor cells. For control of the autoimmune reaction it is essential to design immunomodulatory approaches that overcome rejection while avoiding homeostatic expansion of residual diabetogenic clones.

Apoptosis of purified CD4+ T cell subsets is dominated by cytokine deprivation and absence of other cells in new onset diabetic NOD mice.

BACKGROUND: Regulatory T cells (Treg) play a significant role in immune homeostasis and self-tolerance. Excessive sensitivity of isolated Treg to apoptosis has been demonstrated in NOD mice and humans suffering of type 1 diabetes, suggesting a possible role in the immune dysfunction that underlies autoimmune insulitis. In this study the sensitivity to apoptosis was measured in T cells from new onset diabetic NOD females, comparing purified subsets to mixed cultures. PRINCIPAL FINDINGS: Apoptotic cells are short lived in vivo and death occurs primarily during isolation, manipulation and culture. Excessive susceptibility of CD25(+) T cells to spontaneous apoptosis is characteristic of isolated subsets, however disappears when death is measured in mixed splenocyte cultures. In variance, CD25(-) T cells display balanced sensitivity to apoptosis under both conditions. The isolation procedure removes soluble factors, IL-2 playing a significant role in sustaining Treg viability. In addition, pro- and anti-apoptotic signals are transduced by cell-to-cell interactions: CD3 and CD28 protect CD25(+) T cells from apoptosis, and in parallel sensitize naïve effector cells to apoptosis. Treg viability is modulated both by other T cells and other subsets within mixed splenocyte cultures. Variations in sensitivity to apoptosis are often hindered by fast proliferation of viable cells, therefore cycling rates are mandatory to adequate interpretation of cell death assays. CONCLUSIONS: The sensitivity of purified Treg to apoptosis is dominated by cytokine deprivation and absence of cell-to-cell interactions, and deviate significantly from measurements in mixed populations. Balanced sensitivity of naïve/effector and regulatory T cells to apoptosis in NOD mice argues against the concept that differential susceptibility affects disease evolution and progression.