Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients.

BACKGROUND: Immunosuppressed organ-transplant recipients have an increased incidence of, and mortality from, skin cancer. Nicotinamide (vitamin B3) enhances the repair of ultraviolet (UV) radiation-induced DNA damage, reduces the cutaneous immunosuppressive effects of UV radiation, and reduces the incidence of keratinocyte cancers (including squamous-cell and basal-cell carcinomas) and actinic keratoses among high-risk immunocompetent patients. Whether oral nicotinamide is useful for skin-cancer chemoprevention in organ-transplant recipients is unclear. METHODS: In this phase 3 trial, we randomly assigned, in a 1:1 ratio, organ-transplant recipients who had had at least two keratinocyte cancers in the past 5 years to receive 500 mg of nicotinamide or placebo twice daily for 12 months. Participants were examined for skin lesions by dermatologists at 3-month intervals for 12 months. The primary end point was the number of new keratinocyte cancers during the 12-month intervention period. Secondary end points included the numbers of squamous-cell and basal-cell carcinomas during the 12-month intervention period, the number of actinic keratoses until 6 months after randomization, safety, and quality of life. RESULTS: A total of 158 participants were enrolled, with 79 assigned to the nicotinamide group and 79 to the placebo group. The trial was stopped early owing to poor recruitment. At 12 months, there were 207 new keratinocyte cancers in the nicotinamide group and 210 in the placebo group (rate ratio, 1.0; 95% confidence interval, 0.8 to 1.3; P = 0.96). No significant between-group differences in squamous-cell and basal-cell carcinoma counts, actinic keratosis counts, or quality-of-life scores were observed. Adverse events and changes in blood or urine laboratory variables were similar in the two groups. CONCLUSIONS: In this 12-month, placebo-controlled trial, oral nicotinamide therapy did not lead to lower numbers of keratinocyte cancers or actinic keratoses in immunosuppressed solid-organ transplant recipients. (Funded by the National Health and Medical Research Council; ONTRANS Australian New Zealand Clinical Trials Registry number, ACTRN12617000599370.).

Pretransplant screening for coronary artery disease: data are required before practice change.

Declining rates of peritransplant cardiovascular death, an increasing burden of pretransplant tests, and concerns about the effectiveness of screening candidates for coronary artery disease have led many transplant programs to de-escalate screening protocols. Recent Kidney Disease: Improving Global Outcomes and American Heart Association scientific statements and guidelines neatly summarize current evidence, but also identify areas of need. Here, we argue that key questions should be addressed by adequately powered clinical trials before our long-held screening paradigms are completely rewritten.

Balanced crystalloid solution versus saline in deceased donor kidney transplantation (BEST-Fluids): a pragmatic, double-blind, randomised, controlled trial.

BACKGROUND: Delayed graft function (DGF) is a major adverse complication of deceased donor kidney transplantation. Intravenous fluids are routinely given to patients receiving a transplant to maintain intravascular volume and optimise graft function. Saline (0·9% sodium chloride) is widely used but might increase the risk of DGF due to its high chloride content. We aimed to test our hypothesis that using a balanced low-chloride crystalloid solution (Plasma-Lyte 148) instead of saline would reduce the incidence of DGF. METHODS: BEST-Fluids was a pragmatic, registry-embedded, multicentre, double-blind, randomised, controlled trial at 16 hospitals in Australia and New Zealand. Adults and children of any age receiving a deceased donor kidney transplant were eligible; those receiving a multi-organ transplant or weighing less than 20 kg were excluded. Participants were randomly assigned (1:1) using an adaptive minimisation algorithm to intravenous balanced crystalloid solution (Plasma-Lyte 148) or saline during surgery and up until 48 h after transplantation. Trial fluids were supplied in identical bags and clinicians determined the fluid volume, rate, and time of discontinuation. The primary outcome was DGF, defined as receiving dialysis within 7 days after transplantation. All participants who consented and received a transplant were included in the intention-to-treat analysis of the primary outcome. Safety was analysed in all randomly assigned eligible participants who commenced surgery and received trial fluids, whether or not they received a transplant. This study is registered with Australian New Zealand Clinical Trials Registry, (ACTRN12617000358347), and ClinicalTrials.gov (NCT03829488). FINDINGS: Between Jan 26, 2018, and Aug 10, 2020, 808 participants were randomly assigned to balanced crystalloid (n=404) or saline (n=404) and received a transplant (512 [63%] were male and 296 [37%] were female). One participant in the saline group withdrew before 7 days and was excluded, leaving 404 participants in the balanced crystalloid group and 403 in the saline group that were included in the primary analysis. DGF occurred in 121 (30%) of 404 participants in the balanced crystalloid group versus 160 (40%) of 403 in the saline group (adjusted relative risk 0·74 [95% CI 0·66 to 0·84; p<0·0001]; adjusted risk difference 10·1% [95% CI 3·5 to 16·6]). In the safety analysis, numbers of investigator-reported serious adverse events were similar in both groups, being reported in three (<1%) of 406 participants in the balanced crystalloid group versus five (1%) of 409 participants in the saline group (adjusted risk difference -0·5%, 95% CI -1·8 to 0·9; p=0·48). INTERPRETATION: Among patients receiving a deceased donor kidney transplant, intravenous fluid therapy with balanced crystalloid solution reduced the incidence of DGF compared with saline. Balanced crystalloid solution should be the standard-of-care intravenous fluid used in deceased donor kidney transplantation. FUNDING: Medical Research Future Fund and National Health and Medical Research Council (Australia), Health Research Council (New Zealand), Royal Australasian College of Physicians, and Baxter.

Survival after kidney transplantation compared with ongoing dialysis for people over 70 years of age: A matched-pair analysis.

Kidney transplantation offers improved survival and quality of life compared to dialysis for most recipients; however, benefits for elderly patients (>70 years) remain uncertain. Using the Australia and New Zealand Dialysis and Transplant Registry (2009-2019), elderly transplant recipients were matched to a waitlisted dialysis patient by age, cause of end-stage kidney disease, and dialysis duration (paired controls). We censored dialysis patients at the time of transplant. Survival was compared using stratified Cox regression. Elderly transplant recipients (KTRs) (n = 465) were matched to waitlisted pairs. Transplant group mortality initially exceeded dialysis due to excess infection-related deaths (1.9 transplant versus 0.3 dialysis/100 patient-years, P = .03). Beyond month 9, a progressive survival benefit in favor of transplantation was apparent. Over a median follow-up of 1.7 years, mortality was 38% lower for KTRs (95% confidence interval 0.41-0.94, P = .02), and 5-year survival was 80% KTRs vs 53% dialysis (P < .001). Recipients of living and standard criteria donor kidneys acquired immediate survival advantage compared with dialysis, while recipients of expanded criteria donor's kidneys experienced elevated risk of death for the first 17 months. Compared with remaining on dialysis, elderly KTRs incur an increased risk of early posttransplant mortality but thereafter may anticipate progressively superior survival rates.

The living kidney donor profile index fails to discriminate allograft survival: implications for its use in kidney paired donation programs.

The inclusion of blood group- and human leukocyte antigen-compatible donor and recipient pairs (CPs) in kidney paired donation (KPD) programs is a novel strategy to increase living donor (LD) transplantation. Transplantation from a donor with a better Living Donor Kidney Profile Index (LKDPI) may encourage CP participation in KPD programs. We undertook parallel analyses using data from the Scientific Registry of Transplant Recipients and the Australia and New Zealand Dialysis and Transplant Registry to determine whether the LKDPI discriminates death-censored graft survival (DCGS) between LDs. Discrimination was assessed by the following: (1) the change in the Harrell C statistic with the sequential addition of variables in the LKDPI equation to reference models that included only recipient factors and (2) whether the LKDPI discriminated DCGS among pairs of prognosis-matched LD recipients. The addition of the LKDPI to reference models based on recipient variables increased the C statistic by only 0.02. Among prognosis-matched pairs, the C statistic in Cox models to determine the association of the LKDPI with DCGS was no better than chance alone (0.51 in the Scientific Registry of Transplant Recipient and 0.54 in the Australia and New Zealand Dialysis and Transplant Registry cohorts). We conclude that the LKDPI does not discriminate DCGS and should not be used to promote CP participation in KPD programs.

Obesity is Associated With Delayed Graft Function in Kidney Transplant Recipients: A Paired Kidney Analysis.

Obesity is increasingly prevalent among candidates for kidney transplantation. Existing studies have shown conflicting post-transplant outcomes for obese patients which may relate to confounding bias from donor-related characteristics that were unaccounted for. We used ANZDATA Registry data to compare graft and patient survival between obese (BMI >27.5 kg/m2 Asians; >30 kg/m2 non-Asians) and non-obese kidney transplant recipients, while controlling for donor characteristics by comparing recipients of paired kidneys. We selected transplant pairs (2000-2020) where a deceased donor supplied one kidney to an obese candidate and the other to a non-obese candidate. We compared the incidence of delayed graft function (DGF), graft failure and death by multivariable models. We identified 1,522 pairs. Obesity was associated with an increased risk of DGF (aRR = 1.26, 95% CI 1.11-1.44, p < 0.001). Obese recipients were more likely to experience death-censored graft failure (aHR = 1.25, 95% CI 1.05-1.49, p = 0.012), and more likely to die with function (aHR = 1.32, 95% CI 1.15-1.56, p = 0.001), versus non-obese recipients. Long-term patient survival was significantly worse in obese patients with 10- and 15-year survival of 71% and 56% compared to 77% and 63% in non-obese patients. Addressing obesity is an unmet clinical need in kidney transplantation.

ABO Incompatible Kidney Transplantation Without B-cell Depletion is Associated With Increased Early Acute Rejection: A Single-Center Australian Experience.

We performed a single-center retrospective cohort study of 66 consecutive ABO incompatible kidney transplants (ABOiKT) performed without B-cell depleting therapy. Outcomes were compared to an earlier era performed with rituximab (n = 18) and a contemporaneous cohort of ABO compatible live donor transplants (ABOcKT). Acute rejection within 3 months of transplant was significantly more common after rituximab-free ABOiKT compared to ABOiKT with rituximab (OR 8.8, p = 0.04) and ABOcKT (OR 2.9, p = 0.005) in adjusted analyses. Six recipients of rituximab-free ABOiKT experienced refractory antibody mediated rejection requiring splenectomy, and a further two incurred early graft loss with no such episodes amongst ABOiKT with rituximab or ABOcKT cohorts. Patient and graft survival were similar between groups over a median follow-up of 3.1 years. This observational evidence lends strong support to the continued inclusion of rituximab in desensitization protocols for ABOiKT.

Nutrition in the Management of Kidney Transplant Recipients.

Kidney transplantation offers patients with end stage kidney disease the best outcomes. Concentration on nutrition is pivotal throughout the transplant life course. Nutritional requirements change during each phase of transplantation, from pretransplant evaluation and wait-time, acute transplantation, maintenance and ultimately declining graft function, and care should be taken to consider each stage. In this article we concentrate on addressing each phase, with additional focus on current hot topics of dysglycaemia management and on the impact of diet on gut microbiome.

Interleukin-33 Exacerbates IgA Glomerulonephritis in Transgenic Mice Overexpressing B Cell Activating Factor.

BACKGROUND: The cytokine IL-33 is an activator of innate lymphoid cells 2 (ILC2s) in innate immunity and allergic inflammation. B cell activating factor (BAFF) plays a central role in B cell proliferation and differentiation, and high levels of this protein cause excess antibody production, including IgA. BAFF-transgenic mice overexpress BAFF and spontaneously develop glomerulonephritis that resembles human IgA nephropathy. METHODS: We administered IL-33 or PBS to wild-type and BAFF-transgenic mice. After treating Rag1-deficient mice with IL-33, with or without anti-CD90.2 to preferentially deplete ILC2s, we isolated splenocytes, which were adoptively transferred into BAFF-transgenic mice. RESULTS: BAFF-transgenic mice treated with IL-33 developed more severe kidney dysfunction and proteinuria, glomerular sclerosis, tubulointerstitial damage, and glomerular deposition of IgA and C3. Compared with wild-type mice, BAFF-transgenic mice exhibited increases of CD19+ B cells in spleen and kidney and ILC2s in kidney and intestine, which were further increased by administration of IL-33. Administering IL-33 to wild-type mice had no effect on kidney function or histology, nor did it alter the number of ILC2s in spleen, kidney, or intestine. To understand the role of ILC2s, splenocytes were transferred from IL-33-treated Rag1-deficient mice into BAFF-transgenic mice. Glomerulonephritis and IgA deposition were exacerbated by transfer of IL-33-stimulated Rag1-deficient splenocytes, but not by ILC2 (anti-CD90.2)-depleted splenocytes. Wild-type mice infused with IL-33-treated Rag1-deficient splenocytes showed no change in kidney function or ILC2 numbers or distribution. CONCLUSIONS: IL-33-expanded ILC2s exacerbated IgA glomerulonephritis in a mouse model. These findings indicate that IL-33 and ILC2s warrant evaluation as possible mediators of human IgA nephropathy.

Targeting inflammatory monocytes by immune-modifying nanoparticles prevents acute kidney allograft rejection.

Inflammatory monocytes are a major component of the cellular infiltrate in acutely rejecting human kidney allografts. Since immune-modifying nanoparticles (IMPs) bind to circulating inflammatory monocytes via the specific scavenger receptor MARCO, causing diversion to the spleen and subsequent apoptosis, we investigated the therapeutic potential of negatively charged, 500-nm diameter polystyrene IMPs to prevent kidney allograft rejection. Kidney transplants were performed from BALB/c (H2d) to C57BL/6 (H2b) mice in two groups: controls (allo) and allo mice infused with IMPs. Groups were studied for 14 (acute rejection) or 100 (chronic rejection) days. Allo mice receiving IMPs exhibited superior survival and markedly less acute rejection, with better kidney function, less tubulitis, and diminished inflammatory cell density, cytokine and cytotoxic molecule expression in the allograft and lower titers of donor-specific IgG2c antibody in serum at day 14, as compared to allo mice. Cells isolated from kidneys from allo mice receiving IMPs showed reduced Ly6Chi monocytes, CD11b+ cells and NKT+ cells compared to allo mice. IMPs predominantly bound CD11b+ cells in the bloodstream and CD11b+ and CD11c-B220+ marginal zone B cells in the spleen. In the spleen, IMPs were found predominantly in red pulp, colocalized with MARCO and expression of cleaved caspase-3. At day 100, allo mice receiving IMPs exhibited reduced macrophage M1 responses but were not protected from chronic rejection. IMPs afforded significant protection from acute rejection, inhibiting both innate and adaptive alloimmunity. Thus, our current experimental findings, coupled with our earlier demonstration of IMP-induced protection in kidney ischemia-reperfusion injury, identify IMPs as a potential induction agent in kidney transplantation.

Factors Associated With Advanced Colorectal Neoplasia in Patients With CKD.

RATIONALE & OBJECTIVE: The risk of developing colorectal cancer in patients with chronic kidney disease (CKD) is twice that of the general population, but the factors associated with colorectal cancer are poorly understood. The aim of this study was to identify factors associated with advanced colorectal neoplasia in patients with CKD. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: Patients with CKD stages 3-5, including those treated with maintenance dialysis or transplantation across 11 sites in Australia, New Zealand, Canada, and Spain, were screened for colorectal neoplasia using a fecal immunochemical test (FIT) as part of the Detecting Bowel Cancer in CKD (DETECT) Study. EXPOSURE: Baseline characteristics for patients at the time of study enrollment were ascertained, including duration of CKD, comorbidities, and medications. OUTCOME: Advanced colorectal neoplasia was identified through a 2-step verification process with colonoscopy following positive FIT and 2-year clinical follow-up for all patients. ANALYTICAL APPROACH: Potential factors associated with advanced colorectal neoplasia were explored using multivariable logistic regression. Sensitivity analyses were performed using grouped LASSO (least absolute shrinkage and selection operator) logistic regression. RESULTS: Among 1,706 patients who received FIT-based screening-791 with CKD stages 3-5 not receiving kidney replacement therapy (KRT), 418 receiving dialysis, and 497 patients with a functioning kidney transplant-117 patients (6.9%) were detected to have advanced colorectal neoplasia (54 with CKD stages 3-5 without KRT, 34 receiving dialysis, and 29 transplant recipients), including 9 colorectal cancers. The factors found to be associated with advanced colorectal neoplasia included older age (OR per year older, 1.05 [95% CI, 1.03-1.07], P<0.001), male sex (OR, 2.27 [95% CI, 1.45-3.54], P<0.001), azathioprine use (OR, 2.99 [95% CI, 1.40-6.37], P=0.005), and erythropoiesis-stimulating agent use (OR, 1.92 [95% CI, 1.22-3.03], P=0.005). Grouped LASSO logistic regression revealed similar associations between these factors and advanced colorectal neoplasia. LIMITATIONS: Unmeasured confounding factors. CONCLUSIONS: Older age, male sex, erythropoiesis-stimulating agents, and azathioprine were found to be significantly associated with advanced colorectal neoplasia in patients with CKD.

The Utility of Pre- and Post-Transplant Oral Glucose Tolerance Tests: Identifying Kidney Transplant Recipients With or at Risk of New Onset Diabetes After Transplant.

Background: New onset diabetes after transplant (NODAT) is common in kidney transplant recipients (KTRs). Identifying patients at risk prior to transplant may enable strategies to mitigate NODAT, with a pre-transplant oral glucose tolerance test (OGTT) suggested by the KDIGO 2020 Guidelines for this purpose. Methods: We investigated the utility of pre- and post-transplant OGTTs to stratify risk and diagnose NODAT in a retrospective, single-centre cohort study of all non-diabetic KTRs transplanted between 2003 and 2018. Results: We identified 597 KTRs who performed a pre-transplant OGTT, of which 441 had their post-transplant glycaemic status determined by a clinical diagnosis of NODAT or OGTT. Pre-transplant dysglycaemia was identified in 28% of KTRs and was associated with increasing age (p < 0.001), BMI (p = 0.03), and peritoneal dialysis (p < 0.001). Post-transplant dysglycaemia was common with NODAT and impaired glucose tolerance (IGT) occurring in 143 (32%) and 121 (27%) patients, respectively. Pre-transplant IGT was strongly associated with NODAT development (OR 3.8, p < 0.001). Conclusion: A pre-transplant OGTT identified candidates at increased risk of post-transplant dysglycaemia and NODAT, as diagnosed by an OGTT. Robust prospective trials are needed to determine whether various interventions can reduce post-transplant risk for candidates with an abnormal pre-transplant OGTT.

Rapidly progressive crescentic diabetic nephropathy: two case reports.

Crescents are not a well recognised feature of diabetic nephropathy. We present two cases of patients presenting with a rapid decline in renal function and subacute onset of nephrotic syndrome. Glomerulonephritis screening was negative, and renal biopsy revealed non-necrotising cellular crescents and typical features of late-stage diabetic nephropathy. We review the literature for diabetic nephropathy with crescents and explore possible underlying mechanisms.

Relationship Between Urinary Phosphate and All-Cause and Cardiovascular Mortality in a National Population-Based Longitudinal Cohort Study.

OBJECTIVES: High dietary phosphate intake may lead to adverse outcomes including cardiovascular disease (CVD). Urinary phosphate excretion, a marker of intestinal phosphate absorption, may be a more reliable marker of phosphate homeostasis in steady state than serum phosphate. Studies report good agreement between urine phosphate-to-creatinine ratio (uPiCr) and 24-hour urinary phosphate; however, whether uPiCr is associated with increased risk of CVD or mortality remains uncertain. This study aimed to assess the relationship between uPiCr and all-cause and CVD mortality. DESIGN AND METHODS: This is an observational longitudinal cohort study using data from the population-based national Australian Diabetes, Obesity and Lifestyle study (n = 10,014 participants). Non-linear association between uPiCr and all-cause and CVD mortality was assessed using fractional polynomial transformations. Cox proportional hazards regression models were used to estimate adjusted hazard ratios for all-cause and CVD mortality. RESULTS: Median age [interquartile range] was 50 [41-62] years, and 46% were male. Median uPiCr was 1.38 [1.02-1.79] mmol/mmol. Median follow-up time was 16.9 years with 1,735 deaths. uPiCr was associated with all-cause and CVD mortality in univariate models and when adjusted for age and gender. However, associations were not significant in multivariate models. Sensitivity analyses excluding participants with chronic kidney disease (CKD) revealed a significant J-shaped association between uPiCr and all-cause mortality. Urine phosphate alone showed an association with increased all-cause mortality in a similar J-shape relationship. CONCLUSION: Although no association between uPiCr and all-cause and CVD mortality was observed in multivariate analyses in the whole cohort, a significant relationship between uPiCr and mortality in those without CKD suggests that uPiCr may have predictive validity for future adverse outcomes in people with no CKD.

Death after Kidney Transplantation: An Analysis by Era and Time Post-Transplant.

BACKGROUND: Mortality risk after kidney transplantation can vary significantly during the post-transplant course. A contemporary assessment of trends in all-cause and cause-specific mortality at different periods post-transplant is required to better inform patients, clinicians, researchers, and policy makers. METHODS: We included all first kidney-only transplant recipients from 1980 through 2018 from the Australia and New Zealand Dialysis and Transplant Registry. We compared adjusted death rates per 5-year intervals, using a piecewise exponential survival model, stratified by time post-transplant or time post-graft failure. RESULTS: Of 23,210 recipients, 4765 died with a functioning graft. Risk of death declined over successive eras, at all periods post-transplant. Reductions in early deaths were most marked; however, recipients ≥10 years post-transplant were 20% less likely to die in the current era compared with preceding eras (2015-2018 versus 2005-2009, adjusted hazard ratio, 0.80; 95% confidence interval, 0.69 to 0.90). In 2015-2018, cardiovascular disease was the most common cause of death, particularly in months 0-3 post-transplant (1.18 per 100 patient-years). Cancer deaths were rare early post-transplant, but frequent at later time points (0.93 per 100 patient-years ≥10 years post-transplant). Among 3657 patients with first graft loss, 2472 died and were not retransplanted. Death was common in the first year after graft failure, and the cause was most commonly cardiovascular (50%). CONCLUSIONS: Reductions in death early and late post-transplant over the past 40 years represent a major achievement. Reductions in cause-specific mortality at all time points post-transplant are also apparent. However, relatively greater reductions in cardiovascular death have increased the prominence of late cancer deaths.

Gut Microbial Metabolites Induce Donor-Specific Tolerance of Kidney Allografts through Induction of T Regulatory Cells by Short-Chain Fatty Acids.

BACKGROUND: Short-chain fatty acids derived from gut microbial fermentation of dietary fiber have been shown to suppress autoimmunity through mechanisms that include enhanced regulation by T regulatory cells (Tregs). METHODS: Using a murine kidney transplantation model, we examined the effects on alloimmunity of a high-fiber diet or supplementation with the short-chain fatty acid acetate. Kidney transplants were performed from BALB/c(H2d) to B6(H2b) mice as allografts in wild-type and recipient mice lacking the G protein-coupled receptor GPR43 (the metabolite-sensing receptor of acetate). Allograft mice received normal chow, a high-fiber diet, or normal chow supplemented with sodium acetate. We assessed rejection at days 14 (acute) and 100 (chronic), and used 16S rRNA sequencing to determine gut microbiota composition pretransplantation and post-transplantation. RESULTS: Wild-type mice fed normal chow exhibited dysbiosis after receiving a kidney allograft but not an isograft, despite the avoidance of antibiotics and immunosuppression for the latter. A high-fiber diet prevented dysbiosis in allograft recipients, who demonstrated prolonged survival and reduced evidence of rejection compared with mice fed normal chow. Allograft mice receiving supplemental sodium acetate exhibited similar protection from rejection, and subsequently demonstrated donor-specific tolerance. Depletion of CD25+ Tregs or absence of the short-chain fatty acid receptor GPR43 abolished this survival advantage. CONCLUSIONS: Manipulation of the microbiome by a high-fiber diet or supplementation with sodium acetate modified alloimmunity in a kidney transplant model, generating tolerance dependent on Tregs and GPR43. Diet-based therapy to induce changes in the gut microbiome can alter systemic alloimmunity in mice, in part through the production of short-chain fatty acids leading to Treg cell development, and merits study as a potential clinical strategy to facilitate transplant acceptance.

Dietary Fiber Protects against Diabetic Nephropathy through Short-Chain Fatty Acid-Mediated Activation of G Protein-Coupled Receptors GPR43 and GPR109A.

BACKGROUND: Studies have reported "dysbiotic" changes to gut microbiota, such as depletion of gut bacteria that produce short-chain fatty acids (SCFAs) through gut fermentation of fiber, in CKD and diabetes. Dietary fiber is associated with decreased inflammation and mortality in CKD, and SCFAs have been proposed to mediate this effect. METHODS: To explore dietary fiber's effect on development of experimental diabetic nephropathy, we used streptozotocin to induce diabetes in wild-type C57BL/6 and knockout mice lacking the genes encoding G protein-coupled receptors GPR43 or GPR109A. Diabetic mice were randomized to high-fiber, normal chow, or zero-fiber diets, or SCFAs in drinking water. We used proton nuclear magnetic resonance spectroscopy for metabolic profiling and 16S ribosomal RNA sequencing to assess the gut microbiome. RESULTS: Diabetic mice fed a high-fiber diet were significantly less likely to develop diabetic nephropathy, exhibiting less albuminuria, glomerular hypertrophy, podocyte injury, and interstitial fibrosis compared with diabetic controls fed normal chow or a zero-fiber diet. Fiber beneficially reshaped gut microbial ecology and improved dysbiosis, promoting expansion of SCFA-producing bacteria of the genera Prevotella and Bifidobacterium, which increased fecal and systemic SCFA concentrations. Fiber reduced expression of genes encoding inflammatory cytokines, chemokines, and fibrosis-promoting proteins in diabetic kidneys. SCFA-treated diabetic mice were protected from nephropathy, but not in the absence of GPR43 or GPR109A. In vitro, SCFAs modulated inflammation in renal tubular cells and podocytes under hyperglycemic conditions. CONCLUSIONS: Dietary fiber protects against diabetic nephropathy through modulation of the gut microbiota, enrichment of SCFA-producing bacteria, and increased SCFA production. GPR43 and GPR109A are critical to SCFA-mediated protection against this condition. Interventions targeting the gut microbiota warrant further investigation as a novel renoprotective therapy in diabetic nephropathy.

Development and outcomes of de novo donor-specific antibodies in low, moderate, and high immunological risk kidney transplant recipients.

De novo donor-specific antibodies (dnDSA) play an important role in antibody-mediated rejection (ABMR) and graft failure, yet their development in kidney transplant recipients (KTx) of higher immunological risk has not been characterized. We prospectively determined the incidence of dnDSA at 3 and 12 months posttransplant and assessed their associations with outcomes in recipients stratified by low, moderate, and high immunological risk. Adult KTx were screened for DSA pretransplant, months 3 and 12 posttransplant, and when clinically indicated. Outcomes included incidence of dnDSA, death-censored graft survival (DCGS), and ABMR. Of 371 recipients, 154 (42%) were transplanted across a pretransplant DSA that became undetectable by 12 months posttransplant in 78% of cases. dnDSA were detected in 16% (95% confidence interval [CI]: 12-20%) by 3 months and 23% (95% CI: 18-29%) by 12 months posttransplant. Incidence at 12 months was higher in the moderate (30%) and high-risk groups (29%) compared to the low-risk group (16%). dnDSA were associated with an increased risk of ABMR (hazard ratio [HR] 2.2; 95% CI: 1.1-4.4; P = .04) but were not an independent risk factor for DCGS. In conclusion, dnDSA were more frequent in transplant recipients of higher immune risk and associated with an increased risk of ABMR.

Screening for Asymptomatic Coronary Artery Disease in Waitlisted Kidney Transplant Candidates: A Cost-Utility Analysis.

RATIONALE & OBJECTIVE: On account of the high prevalence of cardiovascular disease in patients with kidney failure, clinical practice guidelines recommend regular screening for asymptomatic coronary artery disease (CAD) in patients on the kidney transplant waitlist. To date, the cost-effectiveness of such screening has not been evaluated. A Canadian-Australasian randomized controlled trial of screening kidney transplant candidates for CAD (CARSK) is currently is being conducted to answer this question. We conducted a cost-utility analysis to determine, before completion of the trial, the cost-effectiveness of no further screening versus regular screening for asymptomatic CAD and to evaluate potential influential variables that may affect results of the economic evaluation. STUDY DESIGN: A modeled cost-utility analysis. SETTING & POPULATION: A theoretical cohort of adult Australian and New Zealand kidney transplant candidates on the waitlist. INTERVENTION: No further screening for asymptomatic CAD versus regular protocolized screening (annual or second yearly) for CAD after kidney transplant waitlisting. OUTCOMES: Incremental cost-effectiveness ratio, reported as cost per quality-adjusted life-year (QALY). MODEL, PERSPECTIVES, & TIMEFRAME: Markov microsimulation model, health system perspective and over a lifetime horizon. RESULTS: In the base case, the incremental cost-effectiveness ratio of no further screening was $11,122 per QALY gained when compared with regular screening. No further screening increased survival by 0.49 life-year or 0.35 QALY. One-way sensitivity analyses identified the costs of transplantation in the first year and CAD prevalence as the most influential variables. Probabilistic sensitivity analyses showed that 94% of the simulations were cost-effective below a willingness-to-pay threshold of $50,000 per QALY gained. LIMITATIONS: Rates of cardiovascular events in waitlisted candidates and transplant recipients are limited in the contemporary era. The results may not be generalizable to populations outside Australia and New Zealand. CONCLUSIONS: No further screening for CAD after waitlisting is likely to be cost-effective and may improve survival. Precision around CAD prevalence estimates and health care resource use will reduce existing uncertainty.