Transplantation Within 6 Months of Registration does not Enhance Survival for Patients with Perihilar Cholangiocarcinoma.

OBJECTIVES: Determine if timing of transplantation affects patient mortality. BACKGROUND: Neoadjuvant therapy and liver transplantation has emerged as an excellent treatment option for select patients with perihilar cholangiocarcinoma (pCCA). However, the optimal timing of transplantation is not known. METHODS: We reviewed all patients registered for a standardized pCCA protocol between 1996 - 2020 at our center. After adjusting for confounders, we examined the association of waiting time with patient mortality in an intention-to-treat cohort (n=392) and those who received a liver transplant (n=256). RESULTS: The median (interquartile range) time from registration to transplant or drop out was 5.74 (3.25-7.06) months. Compared to a short wait time (0-3 months), longer waiting times did not affect all-cause mortality: (3-6 months) hazard ratio (HR) 0.98; 95% CI 0.52-1.84; (6-9 months) HR 0.80; 95% CI 0.39-1.65; (9-12 months) HR 0.56; 95% CI 0.26-1.22. Subgroups with a shorter waiting time had similar survival to those with long waiting times: living donor available HR 0.97; 95% CI 0.67-1.42; AB or B blood group HR 0.93; 95% CI 0.62-1.39. Longer waiting times were associated with decreased all-cause mortality after transplantation (HR 0.92; 95% CI 0.87-0.97). This benefit began after a 6 month waiting time minimum (HR 0.53; 95% CI 0.26-1.10) and increased further after 9 months (HR; 0.43 95% CI 0.20-0.93). Waiting time was not associated with residual adenocarcinoma in the explant (odds ratio 0.99; 95% CI 0.98-1.00). CONCLUSIONS: A waiting time of at least 6 months will optimize results with transplantation without affecting overall (intention-to-treat) patient survival.

Impact of pancreas transplantation alone on kidney function: A multicenter clinical cohort study.

Pancreas transplantation alone (PTA) is a ß cell replacement option for selected patients with type 1 diabetes mellitus; concerns have been raised regarding deterioration in kidney function (KF) after PTA. This retrospective multicenter study assessed actual impact of transplantation and immunosuppression on KF in PTA recipients at three Transplant Centers. The primary composite endpoint 10 years after PTA was >50% eGFR decline, eGFR < 30 mL/min/1.73 m2 , and/or receiving a kidney transplant (KT). Overall, 822 PTA recipients met eligibility. Median baseline and 10-year eGFR (mL/min/1.73 m2 ) were 76.3 (58.1-100.8) and 51.3 (35.3-65.9), respectively. Primary composite endpoint occurred in 98 patients (53.5%) with 45 experiencing a >50% decrease in eGFR by 10 years post-transplant, 38 eGFR < 30 mL/min/1.73 m2 and 49 requiring KT. KF declined most significantly within 6 months post-PTA, more often in females and patients with better preserved GFR up to 5 years with 11.6% kidney failure at 10 years. Patient survival and death-censored graft survival were both 68% at 10 years with overall graft thrombosis rate 8%. KF declined initially after PTA but stabilized with further slow progression. In conclusion, prospective intervention studies are needed to test renal sparing interventions while gathering more granular data.

Prospective Cohort Study Examining the Ability of Performance-Based and Self-Reported Frailty Measures to Predict 30-Day Rehospitalizations After Kidney Transplantation.

Performance-based measures of frailty are associated with healthcare utilization after kidney transplantation (KT) but require in-person assessment. A promising alternative is self-reported frailty. The goal of this study was to examine the ability of performance-based and self-reported frailty measures to predict 30-day rehospitalizations after KT. We conducted a prospective, observational cohort study involving 272 adults undergoing KT at Mayo Clinic in Minnesota, Florida, or Arizona. We simultaneously measured frailty before KT using the physical frailty phenotype (PFP), the short physical performance battery (SPPB), and self-report (the Patient-Reported Outcomes Measurement Information System [PROMIS] 4-item physical function short form v2.0). Both the PFP and self-reported frailty were independently associated with more than a 2-fold greater odds of 30-day rehospitalizations, while the SPPB was not. To our knowledge, this is the first study to assess the prognostic value of all three of the above frailty measures in patients undergoing KT. The PFP is more prognostic than the SPPB when assessing the risk of 30-day rehospitalizations; self-reported frailty can complement the PFP but not replace it. However, the 4-item survey assessing self-reported frailty represents a simple way to identify patients undergoing KT surgery who would benefit from interventions to lower the risk of rehospitalizations.

Changes in Glomerular Volume, Sclerosis, and Ischemia at 5 Years after Kidney Transplantation: Incidence and Correlation with Late Graft Failure.

SIGNIFICANCE STATEMENT: Glomerular volume, ischemic glomeruli, and global glomerulosclerosis are not consistently assessed on kidney transplant biopsies. The authors evaluated morphometric measures of glomerular volume, the percentage of global glomerulosclerosis, and the percentage of ischemic glomeruli and assessed changes in these measures over time to determine whether such changes predict late allograft failure. All three features increased from transplant to five-year biopsy. Kidneys with smaller glomeruli at 5 years had more global glomerulosclerosis and a higher percentage of ischemic-appearing glomeruli. Smaller glomeruli and increasing percentages of global glomerulosclerosis and ischemic glomeruli at 5 years predicted allograft failure. Only increased percentage of ischemic glomeruli predicted allograft failure at 5 years independent of all Banff scores. Glomerular changes reflect pathologic processes that predicted allograft loss; measuring them quantitatively might enhance the current Banff system and provide biomarkers for intervention trials. BACKGROUND: Histology can provide insight into the biology of renal allograft loss. However, studies are lacking that use quantitative morphometry to simultaneously assess changes in mean glomerular volume and in the percentages of globally sclerosed glomeruli (GSG) and ischemic-appearing glomeruli in surveillance biopsies over time to determine whether such changes are correlated with late graft failure. METHODS: We used digital scans of surveillance biopsies (at implantation and at 1 and 5 years after transplantation) to morphometrically quantify glomerular volume and the percentages of GSG and ischemic-appearing glomeruli in a cohort of 835 kidney transplants. Cox proportional hazards models assessed the risk of allograft failure with these three glomerular features. RESULTS: From implantation to 5 years, mean glomerular volume increased by nearly 30% (from 2.8×10 6 to 3.6×10 6 µm 3 ), mean percentage of GSG increased from 3.2% to 13.2%, and mean percentage of ischemic-appearing glomeruli increased from 0.8% to 9.5%. Higher percentages of GSG and ischemic-appearing glomeruli at 5-year biopsy predicted allograft loss. The three glomerular features at 5-year biopsy were related; the percentage of GSG and the percentage of ischemic glomeruli were positively correlated, and both were inversely correlated to glomerular volume. At 5 years, only 5.3% of biopsies had ≥40% ischemic glomeruli, but 45% of these grafts failed (versus 11.6% for <40% ischemic glomeruli). Higher Banff scores were more common with increasing percentages of GSG and ischemia, but at 5 years, only the percentage of ischemic glomeruli added to predictive models adjusted for Banff scores. CONCLUSIONS: Glomerular changes reflect important pathologic processes that predict graft loss. Measuring glomerular changes quantitatively on surveillance biopsies, especially the proportion of ischemic-appearing glomeruli, may enhance the current Banff system and be a useful surrogate end point for clinical intervention trials. PODCAST: This article contains a podcast at.

Convolutional Neural Networks for the Evaluation of Chronic and Inflammatory Lesions in Kidney Transplant Biopsies.

In kidney transplant biopsies, both inflammation and chronic changes are important features that predict long-term graft survival. Quantitative scoring of these features is important for transplant diagnostics and kidney research. However, visual scoring is poorly reproducible and labor intensive. The goal of this study was to investigate the potential of convolutional neural networks (CNNs) to quantify inflammation and chronic features in kidney transplant biopsies. A structure segmentation CNN and a lymphocyte detection CNN were applied on 125 whole-slide image pairs of periodic acid-Schiff- and CD3-stained slides. The CNN results were used to quantify healthy and sclerotic glomeruli, interstitial fibrosis, tubular atrophy, and inflammation within both nonatrophic and atrophic tubuli, and in areas of interstitial fibrosis. The computed tissue features showed high correlation with Banff lesion scores of five pathologists (A.A., A.Dend., J.H.B., J.K., and T.N.). Analyses on a small subset showed a moderate correlation toward higher CD3+ cell density within scarred regions and higher CD3+ cell count inside atrophic tubuli correlated with long-term change of estimated glomerular filtration rate. The presented CNNs are valid tools to yield objective quantitative information on glomeruli number, fibrotic tissue, and inflammation within scarred and non-scarred kidney parenchyma in a reproducible manner. CNNs have the potential to improve kidney transplant diagnostics and will benefit the community as a novel method to generate surrogate end points for large-scale clinical studies.

Automated scoring of total inflammation in renal allograft biopsies.

BACKGROUND: Computer-assisted scoring is gaining prominence in the evaluation of renal histology; however, much of the focus has been on identifying larger objects such as glomeruli. Total inflammation impacts graft outcome, and its quantification requires tools to identify objects at the cellular level or smaller. The goal of the current study was to use CD45 stained slides coupled with image analysis tools to quantify the amount of non-glomerular inflammation within the cortex. METHODS: Sixty renal transplant whole slide images were used for digital image analysis. Multiple thresholding methods using pixel intensity and object size were used to identify inflammation in the cortex. Additionally, convolutional neural networks were used to separate glomeruli from other objects in the cortex. This combined measure of inflammation was then correlated with rescored Banff total inflammation classification and outcomes. RESULTS: Identification of glomeruli on biopsies had high fidelity (mean pixelwise dice coefficient of .858). Continuous total inflammation scores correlated well with Banff rescoring (maximum Pearson correlation .824). A separate set of thresholds resulted in a significant correlation with alloimmune graft loss. CONCLUSIONS: Automated scoring of inflammation showed a high correlation with Banff scoring. Digital image analysis provides a powerful tool for analysis of renal pathology, not only because it is reproducible and can be automated, but also because it provides much more granular data for studies.

Multiple abnormal peripheral blood gene expression assay results are correlated with subsequent graft loss after kidney transplantation.

BACKGROUND: The aim of this study was to correlate peripheral blood gene expression profile (GEP) results during the first post-transplant year with outcomes after kidney transplantation. METHODS: We conducted a prospective, multicenter observational study of obtaining peripheral blood at five timepoints during the first post-transplant year to perform a GEP assay. The cohort was stratified based on the pattern of the peripheral blood GEP results: Tx-all GEP results normal, 1 Not-TX had one GEP result abnormal and >1 Not-TX two or more abnormal GEP results. We correlated the GEP results with outcomes after transplantation. RESULTS: We enrolled 240 kidney transplant recipients. The cohort was stratified into the three groups: TX n = 117 (47%), 1 Not-TX n = 59 (25%) and >1 Not-TX n = 64 (27%). Compared to the TX group, the >1 Not-TX group had lower eGFR (p < .001) and more chronic changes on 1-year surveillance biopsy (p = .007). Death censored graft survival showed inferior graft survival in the >1 Not-TX group (p < .001) but not in the 1 Not-TX group. All graft losses in the >1 Not-TX group occurred after 1-year post-transplant. CONCLUSIONS: We conclude that a pattern of persistently Not-TX GEP assay correlates with inferior graft survival.

Risk factors and outcomes of Pneumocystis pneumonia in solid organ transplant recipients: Impact of posttransplant lymphoproliferative disorder.

BACKGROUND: Pneumocystis jirovecii pneumonia (PJP) is a potentially fatal infection afflicting the immunocompromised population, including solid organ transplant (SOT) recipients. Several risk factors have been described; however, little is known regarding the risk of PJP in SOT recipients with posttransplant lymphoproliferative disorder (PTLD). METHODS: We performed a nested case-control study of SOT recipients diagnosed with PJP from 2000 to 2020. PJP was defined as positive microscopy or polymerase chain reaction testing with compatible symptoms and radiographic findings. Control patients were matched 2:1 by year of first transplant, first transplanted organ, transplant center, and sex. Multivariable conditional logistic regression was performed to test associations with PJP and Cox regression analyzed post-PJP outcomes. RESULTS: Sixty-seven PJP cases were matched to 134 controls. The most common transplant was kidney (55.2%). Fourteen patients had a history of PTLD, 12 of whom developed PJP. After adjusting for age, acute rejection, cytomegalovirus infection, PJP prophylaxis, and lymphopenia (lymphocyte count < .5 × 109 /L), PTLD was independently associated with PJP (OR 14.0, 95% CI 1.7-114.5; p = .014). Lymphopenia was also a significant association (OR 8.2, 95% CI 3.2-20.7; p < .001). PJP was associated with mortality within 90 days of diagnosis (p < .001), but not after 90 days (p = .317). PJP was also associated with 90-day death-censored renal allograft loss (p = .026). CONCLUSIONS: PTLD is independently associated with PJP after adjustment for recognized risk factors. This is likely influenced by PTLD-directed chemotherapy, particularly rituximab-containing regimens. PJP is associated with early mortality, but this effect is not persistent after 90 days. PJP prophylaxis should be considered in SOT recipients with PTLD.

Risk factors and prophylaxis for nocardiosis in solid organ transplant recipients: A nested case-control study.

BACKGROUND: Nocardia is an opportunistic pathogen that primarily affects immunocompromised individuals, including solid organ transplant (SOT) recipients. Up to 2.65% of SOT recipients develop nocardiosis; however, few studies have examined risk factors and prophylaxis for nocardiosis. METHODS: We performed a multicenter, matched nested case-control study of adult SOT recipients with culture-confirmed nocardiosis from 2000 through 2020. Controls were matched up to 2:1 by sex, first transplanted organ, year of transplant, transplant center, and adequate post-transplant follow-up. Multivariable conditional logistic regression was performed to analyze associations with nocardiosis. Cox proportional hazards regression compared 12-month mortality between infection and uninfected patients. RESULTS: One hundred and twenty-three SOT recipients were matched to 245 uninfected controls. Elevated calcineurin inhibitor level, acute rejection, cytomegalovirus infection, lymphopenia, higher prednisone dose, and older age were significantly associated with nocardiosis while trimethoprim-sulfamethoxazole prophylaxis was protective (odds ratio [OR] .34; 95% confidence interval [CI] .13-.84). The effect of prophylaxis was similar, though not always statistically significant, in sensitivity analyses that only included prophylaxis dosed more than twice-per-week (OR .30; 95% CI .11-.80) or restricted to years 2015-2020 (OR .33, 95% CI .09-1.21). Nocardiosis was associated with increased 12-month mortality (hazard ratio 5.47; 95% confidence interval 2.42-12.35). CONCLUSIONS: Multiple measures of immunosuppression and lack of trimethoprim-sulfamethoxazole prophylaxis were associated with nocardiosis in SOT recipients. Effectiveness of prophylaxis may be related to trimethoprim-sulfamethoxazole dose or frequency. Trimethoprim-sulfamethoxazole should be preferentially utilized over alternative agents in SOT recipients with augmented immunosuppression or signs of heightened immunocompromise.

Estimating alloantibody levels in highly sensitized renal allograft candidates: Using serial dilutions to demonstrate a treatment effect in clinical trials.

Small reductions in calculated panel-reactive antibody (cPRA) are associated with increased kidney transplantation in 100% cPRA patients. However, the high level of antibody in these patients is such that desensitization may reduce antibody but not cPRA, thus the cPRA change on undiluted serum with desensitization is an insensitive measure of effectiveness. We evaluated cPRA reduction, calculated per antibody titer, as a desensitization trial endpoint. To accomplish this, two serum samples from 20 kidney transplant candidates with cPRA ≥99.9% (100%) were obtained and serially diluted in triplicate to determine the titer of individual human leukocyte antigen (HLA) antibody specificities. CPRA was computed per dilution to identify the titer at which cPRA drops below 98%. Inter- and intra-assay variability and changes overtime were determined. The dilution needed to reach a cPRA <98% was within 1 titer for replicates from the same sample, with 90% (36/40) concordance. This indicates that only changes >2 titers can be deemed clinically meaningful. The median (IQR) titer difference was 0 (0-1) from baseline to follow-up within 12 months. The cPRA per titer also risk-stratified candidates for trial inclusion. In conclusion, determining the cPRA per titer is a reliable approach to simplify complex antibody data and an ideal endpoint for desensitization trials.

Association of Aspirin Treatment With Cardiac Allograft Vasculopathy Progression and Adverse Outcomes After Heart Transplantation.

BACKGROUND: Enhanced platelet reactivity may play a role in cardiac allograft vasculopathy (CAV) progression. The use of antiplatelet agents after heart transplantation (HT) has been inconsistent and although aspirin (ASA) is often a part of the medication regimen after HT, limited evidence is available on its benefit. METHODS AND RESULTS: CAV progression was assessed by measuring the difference in plaque volume and plaque index between the last follow-up and the baseline coronary intravascular ultrasound examination. Overall, 529 HT recipients were retrospectively analyzed (337 had ≥2 intravascular ultrasound studies). The progression in plaque volume (P = .007) and plaque index (P = .002) was significantly attenuated among patients treated with early ASA (within the first year after HT). Over a 6.7-year follow-up, all-cause mortality was lower with early ASA compared with late or no ASA use (P < .001). No cardiac deaths were observed in the early ASA group, and the risk of CAV-related graft dysfunction was significantly lower in this group (P = .03). However, the composite of all CAV-related events (cardiac death, CAV-related graft dysfunction, or coronary angioplasty) was not significantly different between the groups (P = .16). CONCLUSIONS: Early ASA use after HT may delay CAV progression and decrease mortality and CAV-related graft dysfunction, but does not seem to affect overall CAV-associated events.

Progressive decline of function in renal allografts with normal 1-year biopsies: Gene expression studies fail to identify a classifier.

Histologic findings on 1-year biopsies such as inflammation with fibrosis and transplant glomerulopathy predict renal allograft loss by 5 years. However, almost half of the patients with graft loss have a 1-year biopsy that is either normal or has only interstitial fibrosis. The goal of this study was to determine if there was a gene expression profile in these relatively normal 1-year biopsies that predicted subsequent decline in renal function. Using transcriptome microarrays we measured intragraft mRNA levels in a retrospective Discovery cohort (170 patients with a normal/minimal fibrosis 1-year biopsy, 54 with progressive decline in function/graft loss and 116 with stable function) and developed a nested 10-fold cross-validated gene classifier that predicted progressive decline in renal function (positive predictive value = 38 ± 34%%; negative predictive value = 73 ± 30%, c-statistic = .59). In a prospective, multicenter Validation cohort (270 patients with Normal/Interstitial Fibrosis [IF]), the classifier had a 20% positive predictive value, 85% negative predictive value and .58 c-statistic. Importantly, the majority of patients with graft loss in the prospective study had 1-year biopsies scored as Normal or IF. We conclude predicting graft loss in many renal allograft recipients (i.e., those with a relatively normal 1-year biopsy and eGFR > 40) remains difficult.

Mesangial expansion at 5 years predicts death and death-censored graft loss after renal transplantation.

Death with a functioning graft and death-censored renal allograft failure remain major problems for which effective preventative protocols are lacking. The retrospective cohort study aimed to determine whether histologic changes on a 5-year surveillance kidney biopsy predict adverse outcomes after transplantation in recipients who had: both Type 2 diabetes (T2DM) and obesity (BMI ≥ 30 kg/m2 ) at the time of transplantation (T2DM/Obesity, n = 75); neither (No T2DM/No obesity, n = 78); No T2DM/Obesity (n = 41), and T2DM/No obesity (n = 47). On 5-year biopsies, moderate-to-severe mesangial expansion was more common in the T2DM/Obesity group (Banff mm score ≥2 = 49.3%; Tervaert classification MS ≥ 2b = 26.7%) compared to the other groups (p < .001 for both scores). Risk factors included older age, higher BMI, HbA1C, and triglycerides at 1-year post-transplant. Moderate-to-severe mesangial expansion correlated with death with function (HR 1.74 (1.01, 2.98), p = .045 Banff and 1.89 (1.01, 3.51) p = .045 Tervaert) and with death-censored graft loss (HR 3.2 (1.2, 8.8), p = .02 Banff and HR 3.8 (1.3, 11.5), p = .01 Tervaert) over a mean of 11.6 years of recipient follow-up post-transplant. These data suggest that mesangial expansion in recipients with T2DM and obesity may reflect systemic vascular injury and might be a novel biomarker to predict adverse outcomes post renal transplant.

The need for novel trial designs, master protocols, and research consortia in transplantation.

Large multicenter, randomized controlled trials are the paradigm for determining the efficacy and safety of new therapies. However, applying this classical approach to many areas of transplantation is difficult. For most types of organ transplants, the number of transplants performed is too small for such a trial (lung, pancreas, or vascular composite transplantation are examples). In larger populations such as kidney transplantation, the major unmet needs commonly involve small subsets of patients (antibody-mediated rejection, recurrent renal disease, etc). This issue is not unique to transplantation and has been successfully overcome in other areas of medicine. In oncology, for example, novel trial designs such as adaptive trial design and master protocols are now relatively common. In addition, the existence of multicenter, ongoing clinical research consortia have greatly enhanced the successful implementation of these novel trial designs. In this manuscript, we examine how novel trial designs, master protocols, and research consortia might enhance studies in transplantation aimed at the regulatory approval of new agents. Our premise is that more efficient approaches to clinical trials already exist and, through a coordinated effort by researchers, the pharmaceutical industry, and regulatory bodies like the FDA, they can be implemented in transplantation.

Deep Learning-Based Histopathologic Assessment of Kidney Tissue.

BACKGROUND: The development of deep neural networks is facilitating more advanced digital analysis of histopathologic images. We trained a convolutional neural network for multiclass segmentation of digitized kidney tissue sections stained with periodic acid-Schiff (PAS). METHODS: We trained the network using multiclass annotations from 40 whole-slide images of stained kidney transplant biopsies and applied it to four independent data sets. We assessed multiclass segmentation performance by calculating Dice coefficients for ten tissue classes on ten transplant biopsies from the Radboud University Medical Center in Nijmegen, The Netherlands, and on ten transplant biopsies from an external center for validation. We also fully segmented 15 nephrectomy samples and calculated the network's glomerular detection rates and compared network-based measures with visually scored histologic components (Banff classification) in 82 kidney transplant biopsies. RESULTS: The weighted mean Dice coefficients of all classes were 0.80 and 0.84 in ten kidney transplant biopsies from the Radboud center and the external center, respectively. The best segmented class was "glomeruli" in both data sets (Dice coefficients, 0.95 and 0.94, respectively), followed by "tubuli combined" and "interstitium." The network detected 92.7% of all glomeruli in nephrectomy samples, with 10.4% false positives. In whole transplant biopsies, the mean intraclass correlation coefficient for glomerular counting performed by pathologists versus the network was 0.94. We found significant correlations between visually scored histologic components and network-based measures. CONCLUSIONS: This study presents the first convolutional neural network for multiclass segmentation of PAS-stained nephrectomy samples and transplant biopsies. Our network may have utility for quantitative studies involving kidney histopathology across centers and provide opportunities for deep learning applications in routine diagnostics.

Long-term outcomes of eculizumab-treated positive crossmatch recipients: Allograft survival, histologic findings, and natural history of the donor-specific antibodies.

We aimed to determine the long-term outcomes of eculizumab-treated, positive crossmatch (+XM) kidney transplant recipients compared with +XM and age-matched negative crossmatch (-XM) controls. We performed an observational retrospective study and examined allograft survival, histologic findings, long-term B-cell flow cytometric XM (BFXM), and allograft-loss-associated factors. The mean (SD) posttransplant follow-up was 6.3 (2.5) years in the eculizumab group; 7.6 (3.5), +XM control group; 7.9 (2.5), -XM control group. The overall and death-censored allograft survival rates were similar in +XM groups (P = .73, P = .48) but reduced compared with -XM control patients (P < .001, P < .001). In the eculizumab-treated group, 57.9% (11/19) of the allografts had chronic antibody-mediated rejection, but death-censored allograft survival was 76.6%, 5 years; 75.4%, 7 years. Baseline IgG3 positivity and BFXM ≥300 were associated with allograft loss. C1q positivity was also associated with allograft loss but did not reach statistical significance. Donor-specific antibodies appeared to decrease in eculizumab-treated patients. After excluding patients with posttransplant plasmapheresis, 42.3% (9/21) had negative BFXMs; 31.8% (7/22), completely negative single-antigen beads 1 year posttransplant. Eculizumab-treated +XM patients had reduced allograft survival compared with -XM controls but similar survival to +XM controls. BFXM and complement-activating donor-specific antibodies (by IgG3 and C1q testing) may be used for risk stratification in +XM transplantation.

Modeling graft loss in patients with donor-specific antibody at baseline using the Birmingham-Mayo (BirMay) predictor: Implications for clinical trials.

Predicting which renal allografts will fail and the likely cause of failure is important in clinical trial design to either enrich patient populations to be or as surrogate efficacy endpoints for trials aimed at improving long-term graft survival. This study tests our previous Birmingham-Mayo model (termed the BirMay Predictor) developed in a low-risk kidney transplant population in order to predict the outcome of patients with donor specific alloantibody (DSA) at the time of transplantation and identify new factors to improve graft loss prediction in DSA+ patients. We wanted define ways to enrich the population for future therapeutic intervention trials. The discovery set included 147 patients from Mayo Cohort and the validation set included 111 patients from the Paris Cohort-all of whom had DSA at the time of transplantation. The BirMay predictor performed well predicting 5-year outcome well in DSA+ patients (Mayo C statistic = 0.784 and Paris C statistic = 0.860). Developing a new model did not improve on this performance. A high negative predictive value of greater than 90% in both cohorts excluded allografts not destined to fail within 5 years. We conclude that graft-survival models including histology predict graft loss well, both in DSA+ cohorts as well as DSA- patients.

Using computer-assisted morphometrics of 5-year biopsies to identify biomarkers of late renal allograft loss.

The current Banff scoring system was not developed to predict graft loss and may not be ideal for use in clinical trials aimed at improving allograft survival. We hypothesized that scoring histologic features of digitized renal allograft biopsies using a continuous, more objective, computer-assisted morphometric (CAM) system might be more predictive of graft loss. We performed a nested case-control study in kidney transplant recipients with a surveillance biopsy obtained 5 years after transplantation. Patients that developed death-censored graft loss (n = 67) were 2:1 matched on age, gender, and follow-up time to controls with surviving grafts (n = 134). The risk of graft loss was compared between CAM-based models vs a model based on Banff scores. Both Banff and CAM identified chronic lesions associated with graft loss (chronic glomerulopathy, arteriolar hyalinosis, and mesangial expansion). However, the CAM-based models predicted graft loss better than the Banff-based model, both overall (c-statistic 0.754 vs 0.705, P < .001), and in biopsies without chronic glomerulopathy (c-statistic 0.738 vs 0.661, P < .001) where it identified more features predictive of graft loss (% luminal stenosis and % mesangial expansion). Using 5-year renal allograft surveillance biopsies, CAM-based models predict graft loss better than Banff models and might be developed into biomarkers for future clinical trials.

Changes in the gut microbiome and fermentation products concurrent with enhanced longevity in acarbose-treated mice.

BACKGROUND: Treatment with the α-glucosidase inhibitor acarbose increases median lifespan by approximately 20% in male mice and 5% in females. This longevity extension differs from dietary restriction based on a number of features, including the relatively small effects on weight and the sex-specificity of the lifespan effect. By inhibiting host digestion, acarbose increases the flux of starch to the lower digestive system, resulting in changes to the gut microbiota and their fermentation products. Given the documented health benefits of short-chain fatty acids (SCFAs), the dominant products of starch fermentation by gut bacteria, this secondary effect of acarbose could contribute to increased longevity in mice. To explore this hypothesis, we compared the fecal microbiome of mice treated with acarbose to control mice at three independent study sites. RESULTS: Microbial communities and the concentrations of SCFAs in the feces of mice treated with acarbose were notably different from those of control mice. At all three study sites, the bloom of a single bacterial taxon was the most obvious response to acarbose treatment. The blooming populations were classified to the largely uncultured Bacteroidales family Muribaculaceae and were the same taxonomic unit at two of the three sites. Propionate concentrations in feces were consistently elevated in treated mice, while the concentrations of acetate and butyrate reflected a dependence on study site. Across all samples, Muribaculaceae abundance was strongly correlated with propionate and community composition was an important predictor of SCFA concentrations. Cox proportional hazards regression showed that the fecal concentrations of acetate, butyrate, and propionate were, together, predictive of mouse longevity even while controlling for sex, site, and acarbose. CONCLUSION: We observed a correlation between fecal SCFAs and lifespan in mice, suggesting a role of the gut microbiota in the longevity-enhancing properties of acarbose. Treatment modulated the taxonomic composition and fermentation products of the gut microbiome, while the site-dependence of the responses illustrate the challenges facing reproducibility and interpretation in microbiome studies. These results motivate future studies exploring manipulation of the gut microbial community and its fermentation products for increased longevity, testing causal roles of SCFAs in the observed effects of acarbose.

Relay optical function and pre-construction results of a Giant Steerable Science Mirror for a thirty meter telescope.

The Giant Steerable Science Mirror (GSSM) is the tertiary mirror system of the Thirty Meter Telescope (TMT) that relays optical beams from the secondary mirror to active instruments on Nasmyth platforms. One of the key technologies involved in GSSM functions is the error budget allocation from the system engineering of TMT. A novel approach of error analysis and allocation with strong adaptability, which is based on normalized Point Source Sensitivity (PSSn), is proposed. The relay optical function including the quality of the wavefront, the rationality of the mechanism, and the stability of the light were achieved based on the proposed method. The experiments validate the proposed method.