Faculty Bibliography

Current methods to remove donor-specific HLA antibody (DSA) from sensitized patients remain imperfect. We tested novel approaches to desensitization using an animal model of allogeneic sensitization with skin grafts from dark agouti (DA) to Lewis rats. At the peak IgG alloantibody response we transplanted DA kidneys into nephrectomized Lewis recipients (n = 6) and all died within 10 days from antibody-mediated rejection (AMR). Allogeneic hematopoietic stem cell transplants (HSCT) from DA donors failed to engraft after lethal or sub-lethal irradiation. Sensitized rats given lethal irradiation plus syngeneic green fluorescent protein (GFP) + HSCT had repopulation of blood, spleen, thymus and lymph nodes by GFP+ cells. At 2 months after HSCT, serum DSA levels were reduced 60-70% and DSA (IgG) production in cultured splenocytes was also significantly decreased. However, there was only a modest improvement in graft survival from an average of 6.5 to 13.9 (n = 9) days. Adding seven daily doses of fludarabine to the preconditioning regimen resulted in long-term survival (>90 days) in 7 out of 10 rat kidney allografts. We conclude that syngeneic HSCT performed after preconditioning with irradiation and fludarabine can reduce DSA, prevent DSA rebound and AMR, enabling successful transplantation in animals with strong antibody reactivity to the donor MHC.

BACKGROUND: Bortezomib has been used to reduce HLA antibody in patients either before transplantation or as treatment for antibody-mediated rejection (AMR). Reports on its efficacy show mixed results. The mechanism of action of this agent is via proteasome inhibition. The primary route of synthesis of HLA class I molecules is dependent on peptide generation by the proteasome, whereas that of class II is not. We observed a differential effect of bortezomib on class I versus class II antibody and hypothesized that this was related to a reduced expression of class I HLA antigens. METHODS: The effect of bortezomib on HLA antibody levels was evaluated in 13 patients who were desensitized for incompatible renal transplantation. We calculated the percent difference in HLA antibody level before and after bortezomib treatment and the impact of bortezomib on HLA expression in lymphocytes of healthy control subjects. RESULTS: On average, the level of HLA class I donor-specific antibody (DSA) decreased by 32%, whereas that of class II DSA increased by 29%. In vitro bortezomib treatment of lymphocytes resulted in a mean decrease of 23% in MHC class I expression on B lymphocytes and no change (+1.08%) in MHC class II expression (P=0.0003). The amount of intracellular class I molecules was reduced by a mean of 29% with bortezomib. CONCLUSION: These data indicate that bortezomib reduces HLA class I antibody more effectively than class II antibody. This difference may be due to the reduced expression of class I molecules resulting from treatment with this proteasome inhibitor.

The impact of kidney donation on the ability to change or initiate health or life insurance following donation is unknown. To quantify this risk, we surveyed 1046 individuals who donated a kidney at our center between 1970 and 2011. Participants were asked whether they changed or initiated health or life insurance after donation, and if they had any difficulty doing so. Among 395 donors who changed or initiated health insurance after donation, 27 (7%) reported difficulty; among those who reported difficulty, 15 were denied altogether, 12 were charged a higher premium and 8 were told they had a preexisting condition because they were kidney donors. Among 186 donors who changed or initiated life insurance after donation, 46 (25%) reported difficulty; among those who reported difficulty, 23 were denied altogether, 27 were charged a higher premium and 17 were told they had a preexisting condition because they were kidney donors. In this single-center study, a high proportion of kidney donors reported difficulty changing or initiating insurance, particularly life insurance. These practices by insurers create unnecessary burden and stress for those choosing to donate and could negatively impact the likelihood of live kidney donation among those considering donation.

Incompatible live donor kidney transplantation (ILDKT) offers a survival advantage over dialysis to patients with anti-HLA donor-specific antibody (DSA). Program-specific reports (PSRs) fail to account for ILDKT, placing this practice at regulatory risk. We collected DSA data, categorized as positive Luminex, negative flow crossmatch (PLNF) (n = 185), positive flow, negative cytotoxic crossmatch (PFNC) (n = 536) or positive cytotoxic crossmatch (PCC) (n = 304), from 22 centers. We tested associations between DSA, graft loss and mortality after adjusting for PSR model factors, using 9669 compatible patients as a comparison. PLNF patients had similar graft loss; however, PFNC (adjusted hazard ratio [aHR] = 1.64, 95% confidence interval [CI]: 1.15-2.23, p = 0.007) and PCC (aHR = 5.01, 95% CI: 3.71-6.77, p < 0.001) were associated with increased graft loss in the first year. PLNF patients had similar mortality; however, PFNC (aHR = 2.04; 95% CI: 1.28-3.26; p = 0.003) and PCC (aHR = 4.59; 95% CI: 2.98-7.07; p < 0.001) were associated with increased mortality. We simulated Centers for Medicare & Medicaid Services flagging to examine ILDKT's effect on the risk of being flagged. Compared to equal-quality centers performing no ILDKT, centers performing 5%, 10% or 20% PFNC had a 1.19-, 1.33- and 1.73-fold higher odds of being flagged. Centers performing 5%, 10% or 20% PCC had a 2.22-, 4.09- and 10.72-fold higher odds. Failure to account for ILDKT's increased risk places centers providing this life-saving treatment in jeopardy of regulatory intervention.

BACKGROUND: Although several strategies for treating early antibody-mediated rejection (AMR) in kidney transplants have been investigated, evidence on treatment of late AMR manifesting after 6 months is sparse. In this single-center series, we present data on 23 consecutive patients treated for late AMR. METHODS: Late AMR was diagnosed using Banff 2007 criteria along with presence of donor-specific antibodies (DSA) and acute rise in serum creatinine (SCr). Response to therapy was assessed by improvement in SCr, histologic improvement, and decline in DSA strength. RESULTS: Overall, 17% (4/23) had documented nonadherence while 69% (16/23) had physician-recommended reduction in immunosuppression before AMR. Eighteen patients (78%) were treated with plasmapheresis or low-dose IVIg+rituximab; 11 (49%) with refractory AMR also received one to three cycles of bortezomib. While there was an improvement (P=0.02) in mean SCr (2.4 mg/dL) at the end of therapy compared with SCr at the time of diagnosis (2.9 mg/dL), this improvement was not sustained at most recent follow-up. Eleven (48%) patients had no histologic resolution on follow-up biopsy. Lack of histologic response was associated with older patients (odds ratio [OR]=3.17; P=0.04), presence of cytotoxic DSA at time of diagnosis (OR=200; P=0.04), and severe chronic vasculopathy (cv>/=2) on index biopsy (OR=50; P=0.06). CONCLUSIONS: A major setting in which late AMR occurred in our cohort was reduction or change in immunosuppression. Our data demonstrate an inadequate response of late AMR to current and novel (bortezomib) therapies. The benefits of therapy need to be counterweighed with potential adverse effects especially in older patients, large antibody loads, and chronic allograft vasculopathy.

BACKGROUND: The correlation between histopathologic phenotypes and allograft outcomes among patients desensitized for donor-specific antibody (HLA-incompatible) is unknown. METHODS: We analyzed 1-year biopsies from desensitized recipients transplanted between 1999 and 2010 and estimated graft survival for each histologic phenotype identified. Median time posttransplant for the 1-year biopsy was 367 days (interquartile range 357-388 days) and median follow-up of all patients post-1-year biopsy was 42 months (interquartile range 19.5-65 months). RESULTS: Transplant glomerulopathy was present in 25.0% of biopsies and resulted in worse graft survival (66.7% vs. 96.7%, P<0.001). C4d positivity and transplant glomerulopathy together portended exceptionally poor graft survival (33.3% vs. 97.2%, P<0.001). Microcirculation inflammation was prevalent, with glomerulitis and peritubular capillaritis found in 60.0% and 47.6% of 1-year biopsies, respectively. Glomerulitis was associated with worse graft survival (82.1% vs. 98.1%, P=0.004), whereas capillaritis was not (88.1% vs. 97.7% respectively, P=0.091). Among C4d-negative HLA-incompatible recipients (82.6% of biopsies), no difference in graft survival was observed between patients with or without microcirculation inflammation in contrast to previous reports by other investigators. Patients who had no C4d deposition, transplant glomerulopathy, or microcirculation inflammation had a 100.0% graft survival. On Cox regression analysis, no independent histopathological parameter was associated with graft survival. CONCLUSIONS: We have identified several histopathologic phenotypes in HLA-incompatible kidney recipients that correlate with allograft outcomes. Characterization of these phenotypes is the first step towards better understanding the pathophysiologic basis of chronic antibody-mediated allograft injury and individualizing therapeutic intervention.

BACKGROUND: Recipients of incompatible allografts are at increased risk of graft loss. We hypothesized that analysis of sequential biopsies from these grafts could define progression of graft lesions and identify features predictive of progression. METHODS: We studied the time course of histologic injury in 745 kidney graft biopsies from 129 patients transplanted with a positive crossmatch human leukocyte antigen-incompatible kidney between 2000 and 2010 (follow-up of 1-9 years). RESULTS: Graft survival was 98% at 1 year and 80% at 5 years after transplantation. Throughout follow-up, 70% of patients experienced rejection, with 52% showing subclinical rejection in the first year. Cell-mediated rejection was more frequent than antibody-mediated rejection throughout follow-up. Transplant glomerulopathy (TxGN; cg>/=1) developed in 47% of patients over the period of the study, as early as 3 months in a few patients. TxGN was preceded by glomerulitis in more than 90% of cases, with a median time interval of 12 months. Glomerulitis and detectable posttransplantation donor-specific antibodies were risk factors for TxGN (P<0.0001 and P<0.05). C4d-negative antibody-mediated rejection manifesting as capillaritis (g>/=1 and ptc>/=1) with detectable donor-specific antibodies was observed in some recipients (<20%). There was progressively higher average tubulointerstitial scarring (ci+ct) from 3 to 6 to 12 months (P<0.001). CONCLUSIONS: Despite good graft survival, a significant incidence of biopsy-proven rejection occurred in this subset of closely monitored human leukocyte antigen-incompatible recipients throughout follow-up. Microcirculation inflammation, particularly glomerulitis, irrespective of C4d, is associated with a high risk of development of TxGN at 1 year.