John P. Vella

Germline Mutations in the Extracellular Domains of the 55 kDa TNF Receptor, TNFR1, Define a Family of Dominantly Inherited Autoinflammatory Syndromes

Autosomal dominant periodic fever syndromes are characterized by unexplained episodes of fever and severe localized inflammation. In seven affected families, we found six different missense mutations of the 55 kDa tumor necrosis factor receptor (TNFR1), five of which disrupt conserved extracellular disulfide bonds. Soluble plasma TNFR1 levels in patients were approximately half normal. Leukocytes bearing a C52F mutation showed increased membrane TNFR1 and reduced receptor cleavage following stimulation. We propose that the autoinflammatory phenotype results from impaired downregulation of membrane TNFR1 and diminished shedding of potentially antagonistic soluble receptor. TNFR1-associated periodic syndromes (TRAPS) establish an important class of mutations in TNF receptors. Detailed analysis of one such mutation suggests impaired cytokine receptor clearance as a novel mechanism of disease.

Donor Toll-like receptor 4 contributes to ischemia and reperfusion injury following human kidney transplantation

While studies in animal models have linked Toll-like receptor (TLR) 4 signaling to kidney injury induced by ischemia and reperfusion, the relevance of TLR4 activation to allograft injury in human kidney transplants is unknown. Here we show that TLR4 is constitutively expressed within all donor kidneys but is significantly higher in deceased-, compared with living-donor organs. Tubules from deceased- but not living-donor kidneys also stained positively for high-mobility group box-1 (HMGB1), a known endogenous TLR4 ligand. In vitro stimulation of human tubular cells with HMGB1, in a TLR4-dependent system, confirmed that HMGB1 can stimulate proinflammatory responses through TLR4. To assess the functional significance of TLR4 in human kidney transplantation, we determined whether TLR4 mutations that confer diminished affinity for HMGB1 influence intragraft gene-expression profiles and immediate graft function. Compared with kidneys expressing WT alleles, kidneys with a TLR4 loss-of-function allele contained less TNFα, MCP-1, and more heme oxygenase 1 (HO-1), and exhibited a higher rate of immediate graft function. These results represent previously undetected evidence that donor TLR4 contributes to graft inflammation and sterile injury following cold preservation and transplantation in humans. Targeting TLR4 signaling may have value in preventing or treating postischemic acute kidney injury after transplantation.

EFFECT OF RENAL TRANSPLANTATION ON BIOMARKERS OF INFLAMMATION AND OXIDATIVE STRESS IN END-STAGE RENAL DISEASE PATIENTS

Background. Chronic kidney disease patients have a high prevalence of inflammation and oxidative stress, and this has been associated with the excess cardiovascular morbidity and mortality observed in this population. Because maintenance hemodialysis is ineffective in controlling these factors, we hypothesized that restoration of kidney function by transplantation would be required to improve uremic inflammation and oxidative stress. Methods. This was a prospective cohort study evaluating time-dependent changes in biomarkers of inflammation and oxidative stress before and after renal transplantation. Nineteen end-stage renal disease (ESRD) patients (age 38.3±13.7 years, 58% male, 95% white, 21% diabetic) undergoing living-donor renal transplantation were enrolled. C-reactive protein (CRP), interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, protein-associated carbonyl content, and F2-isoprostanes were assessed at 1 week pretransplantation and at 1 week and 2 months posttransplantation. Results. Pretransplant levels of the pro-inflammatory proteins IL-6, TNF-α, and CRP, as well as the oxidative stress markers plasma protein carbonyls and F2-isoprostanes, were significantly elevated in ESRD patients compared with healthy control subjects. We observed rapid and significant declines in all of these biomarkers after transplantation that persisted for 2 months. Conclusions. Our findings indicate that restoration of renal function by transplantation improves the chronic inflammation and increased oxidative stress associated with uremia, which may contribute to the improved survival afforded to ESRD patients by renal transplantation.

Regulatory functions of self-restricted MHC class II allopeptide-specific Th2 clones in vivo

We studied T-cell clones generated from grafts of rejecting and tolerant animals and investigated the regulatory function of Th2 clones in vitro and in vivo. To prevent allograft rejection, we treated LEW strain recipient rats of WF strain kidney grafts with CTLA4Ig to block CD28-B7 costimulation. We then isolated epitope-specific T-cell clones from the engrafted tissue, using a donor-derived immunodominant class II MHC allopeptide presented by recipient antigen-presenting cells. Acutely rejected tissue from untreated animals yielded self-restricted, allopeptide-specific T-cell clones that produced IFN-gamma, whereas clones from tolerant animals produced IL-4 and IL-10. Adoptive transfer into naive recipients of Th1 clones, but not Th2 clones, induced alloantigen-specific delayed-type hypersensitivity (DTH) responses. In addition, Th2 clones suppressed DTH responses mediated by Th1 clones in vivo and blocked Th1 cell proliferation and IFN-gamma production in vitro. A pilot human study showed that HLA-DR allopeptide-specific T-cell clones generated from patients with chronic rejection secrete Th1 cytokines, whereas those from patients with stable graft function produce Th2 cytokines in response to donor-specific HLA-DR allopeptides. We suggest that self-restricted alloantigen-specific Th2 clones may regulate the alloimmune responses and promote long-term allograft survival and tolerance.

Cellular and humoral mechanisms of vascularized allograft rejection induced by indirect recognition of donor MHC allopeptides.

INTRODUCTION To investigate the role and mechanisms of indirect allorecognition in allograft rejection, we studied whether priming T cells with donor-derived MHC allopeptides could accelerate rejection in a vascularized allograft model. METHODS Lewis recipients of fully mismatched Wistar Furth cardiac allografts were immunized before transplantation with donor MHC allopeptides. RESULTS Animals immunized with immunogenic class II MHC allopeptides rejected their grafts in a significantly accelerated fashion compared with controls. Additional studies demonstrated that a single immunodominant RT1.D (HLA-DR like) allopeptide was responsible for accelerating the rejection process. Histological analysis of rejected allografts revealed marked vascular rejection in the accelerated, although not the control, group as well as severe cellular rejection. Peak production of IgM and IgG donor-specific alloantibodies was detected by flow cytometry 1 week earlier in the sera of the accelerated group compared with the control group. Immunohistological analysis of grafts from the accelerated compared with the control group showed increased endothelial deposition of IgG2b, C3, and fibrin, and up-regulation of class II MHC molecule expression. Increased intragraft expression of interferon-y and the interferon-gamma-induced chemokines, inducible protein-10 and Mig, and infiltration by activated mononuclear cells expressing CXCR3, the receptor for inducible protein-10 and Mig, was also seen. CONCLUSION These novel data provide evidence of a definitive link between indirect allorecognition of donor-derived MHC class II peptides and the cellular and humoral mechanisms of vascularized allograft rejection.

Tubular Expression of KIM-1 Does not Predict Delayed Function After Transplantation

Injured epithelial cells of the proximal tubule upregulate the glycoprotein kidney injury molecule 1 (KIM-1), suggesting its potential as a biomarker of incipient kidney allograft injury. It is unknown whether KIM-1 expression changes in kidney allografts with delayed graft function (DGF), which often follows ischemia-reperfusion injury. Here, we prospectively measured KIM-1 RNA and protein expression in preperfusion biopsies of 30 living- and 85 deceased-donor kidneys and correlated the results with histologic and clinical outcomes after transplantation. We detected KIM-1 expression in 62% of deceased-donor kidneys and only 13% of living-donor kidneys (P < 0.0001). The level of KIM-1 expression before reperfusion correlated inversely with renal function at the time of procurement and correlated directly with the degree of interstitial fibrosis. Surprising, however, we did not detect a significant correlation between KIM-1 staining intensity and the occurrence of DGF. Our findings are consistent with a role for KIM-1 as an early indicator of tubular injury but do not support tissue KIM-1 measurement before transplantation to identify kidneys at risk for DGF.

Inhibition of allorecognition by a human class II MHC–derived peptide through the induction of apoptosis

The interaction of the T-cell receptor with the major histocomatibility complex (MHC)-peptide complex is central to T-cell activation. Variation in the nature of the peptide bound within the groove of the MHC molecule may result in an altered T-cell response. Because some naturally processed peptides bound within the groove of the class II MHC molecule are derived from the MHC molecules themselves, we studied the inhibitory effects of synthetic class II MHC peptides on alloimmune responses in vitro. Three peptides derived from a highly conserved region of the class II MHC alpha chains inhibited the rat mixed lymphocyte response (MLR) in a dose-dependent manner, with the human HLA-DQA1 peptide also inhibiting the human and mouse MLR. No effect was seen on mitogen-induced T-cell proliferation. HLA-DQA1 inhibited cytolytic T lymphocyte (CTL) generation in a dose-response fashion, with no reduction in preformed CTL killing, suggesting that the inhibitory effect is targeted at CD4(+) T-cell function. Cell-cycle analysis by flow cytometry showed that restimulation of primed T cells in the presence of HLA-DQA1 resulted in increased apoptosis, whereas unstimulated cells were not affected. These data demonstrate that synthetic peptides derived from highly conserved regions of the class II MHC alpha chain can alter CD4(+) T-lymphocyte alloimmune responses in vitro, and this effect is mediated by the induction of apoptosis in activated T cells.

Direct and Indirect Costs Following Living Kidney Donation: Findings From the KDOC Study.

Some living kidney donors (LKDs) incur costs associated with donation, although these costs are not well characterized in the United States. We collected cost data in the 12 mo following donation from 182 LKDs participating in the multicenter prospective Kidney Donor Outcomes Cohort (KDOC) Study. Most LKDs (n = 167, 92%) had one direct cost or more following donation, including ground transportation (86%), health care (41%), meals (53%), medications (36%), lodging (23%), and air transportation (12%). LKDs missed 33 072 total work hours, 40% of which were unpaid and led to

Predonation Direct and Indirect Costs Incurred by Adults Who Donated a Kidney: Findings From the KDOC Study

302 175 in lost wages (mean

Kidney allograft biopsy: timing to complications

1660). Caregivers lost