Unexpected Medical Conditions Discovered During Live Donor Kidney Evaluation: Single Center Study

OBJECTIVES

Living donor kidney transplantation (LDKT) is the preferred method of treatment for patients with end-stage kidney disease. Potential living kidney donors (PLKD) are evaluated through a thorough medical, psychological and surgical work-up to ensure successful transplantation with minimal risks to all parties involved. The transplant center at Rhode Island Hospital has noticed an increasing number of PLKDs excluded from donation due to conditions newly diagnosed during the screening process. Our objective is to understand the local trends underlying the high PLKD exclusion rates in the context of newly diagnosed conditions, age, race, and sex of the excluded donors.

STUDY DESIGN AND METHODS

Our study is a retrospective electronic medical record review of the 429 PLKDs screened at Rhode Island Hospital Kidney Transplant Center between December 2012 and April 2023. Age, race, gender, relationship to recipient, and reasons for exclusion were collected from the medical record for each PLKD.

CONCLUSION

115 of the 429 total PLKDs screened were excluded for newly diagnosed conditions, the most common of which were renal issues (49%), diabetes mellitus (33%), and hypertension (13%), with many comorbid diagnoses. While these donors were able to receive proper treatment after their diagnosis, the earliest intervention possible yields the best prognosis. The high prevalence of treatable yet undiagnosed conditions raise many public health concerns, such as primary care gaps or discontinuous healthcare, and increases awareness about the importance of follow-up care for the excluded PLKDs.

Obstructive Uropathy due to Bilateral Sliding Hernia in a Renal Transplant Patient with Incidental RCC in Native Kidney

BACKGROUND

Ureteral obstruction is a common complication after kidney transplantation. Ureteral obstruction caused by inguinal hernia, however, is a rare complication of transplantation and requires urgent surgical repair to prevent allograft loss.  Case presentation: A 58-year-old man presented with allograft dysfunction 18-years after renal transplant. He was compliant with medications and given the long duration of allograft survival, a primary renal etiology was suspected. Thus, the initial work-up included allograft biopsy that was unremarkable. Three months later, worsening allograft function prompted further evaluation. At this time, allograft ultrasound and computed tomography led to the diagnosis of ureteral obstruction due to uretero-inguinal herniation of left kidney transplant secondary to bilateral sliding inguinal hernias. The patient was also found to have incidental renal cell carcinoma of the left native kidney. A percutaneous nephrostomy tube was placed and then followed by surgical repair with ureteral reimplantation, herniorrhaphy with mesh, and left native nephrectomy.

CONCLUSIONS

Mechanical obstruction can occur years after kidney transplantation. Even though it is uncommon, ureteral obstruction due to inguinal herniation is critical. Early detection of this complication and surgery can salvage the allograft and prolong function.

ABBREVIATIONS

RCC: renal cell carcinoma; PCN: Percutaneous Nephrostomy; ACKD: Acquired Cystic Kidney Disease.

Sleep duration and cognitive function among older adults with chronic kidney disease: results from the National Health and Nutrition Examination Survey (2011-2014)

BACKGROUND

Short and long sleep durations are associated with cognitive dysfunction. Given the increased prevalence of sleep abnormalities in the chronic kidney disease (CKD) population, we tested whether the association between sleep duration and cognitive function differed between older adults with and without CKD.

METHODS

This was a study of 3215 older adults (age ≥60 years) enrolled in the National Health and Nutrition Examination Survey (2011-14) evaluating sleep duration, cognitive function (immediate recall, delayed recall, verbal fluency, executive function and processing speed and global cognition) and kidney function. We quantified the association between sleep duration and cognitive function using linear regression and tested whether the associations differed among those with CKD and without using a Wald test for interaction.

RESULTS

Among 3215 participants, 13.3% reported 2-5 hours of sleep/day, 75.2% reported 6-8 hours, and 11.5% reported ≥9 hours. Persons with CKD were more likely to sleep ≥9 hours [odds ratio 1.73 (95% confidence interval 1.22-2.46)]. Among participants with CKD, those with a sleep duration ≥9 hours demonstrated worse global cognitive function (P for interaction = .01), immediate recall (P for interaction = .01) and verbal fluency (P for interaction = .004) than those with a sleep duration of 6-8 h; no differences were observed for participants with CKD who slept 2-5 hours. Among participants without CKD, sleep was not associated with any measures of cognitive function.

CONCLUSIONS

Longer sleep duration is associated with worse cognitive function only among persons with CKD, and global cognition, delayed recall and verbal fluency are particularly affected. Studies should identify interventions to improve sleep patterns and quality in this population.

Ethical analysis examining the prioritisation of living donor transplantation in times of healthcare rationing

The transplant community has faced unprecedented challenges balancing risks of performing living donor transplants during the COVID-19 pandemic with harms of temporarily suspending these procedures. Decisions regarding postponement of living donation stem from its designation as an elective procedure, this despite that the Centers for Medicare and Medicaid Services categorise transplant procedures as tier 3b (high medical urgency-do not postpone). In times of severe resource constraints, health systems may be operating under crisis or contingency standards of care. In this manuscript, the United Network for Organ Sharing Ethics Workgroup explores prioritisation of living donation where health systems operate under contingency standards of care and provide a framework with recommendations to the transplant community on how to approach living donation in these circumstances.To guide the transplant community in future decisions, this analysis suggests that: (1) living donor transplants represent an important option for individuals with end-stage liver and kidney disease and should not be suspended uniformly under contingency standards, (2) exposure risk to SARS-CoV-2 should be balanced with other risks, such as exposure risks at dialysis centres. Because many of these risks are not quantifiable, donors and recipients should be included in discussions on what constitutes acceptable risk, (3) transplant hospitals should strive to maintain a critical transplant workforce and avoid diverting expertise, which could negatively impact patient preparedness for transplant, (4) transplant hospitals should consider implementing protocols to ensure early detection of SARS-CoV-2 infections and discuss these measures with donors and recipients in a process of shared decision-making.

Inhibition of MLL1-menin interaction attenuates renal fibrosis in obstructive nephropathy

Mixed lineage leukemia 1 (MLL1), a histone H3 lysine 4 (H3K4) methyltransferase, exerts its enzymatic activity by interacting with menin and other proteins. It is unclear whether inhibition of the MLL1-menin interaction influences epithelial-mesenchymal transition (EMT), renal fibroblast activation, and renal fibrosis. In this study, we investigated the effect of disrupting MLL1-menin interaction on those events and mechanisms involved in a murine model of renal fibrosis induced by unilateral ureteral obstruction (UUO), in cultured mouse proximal tubular cells and renal interstitial fibroblasts. Injury to the kidney increased the expression of MLL1 and menin and H3K4 monomethylation (H3K4me1); MLL1 and menin were expressed in renal epithelial cells and renal interstitial fibroblasts. Inhibition of the MLL1-menin interaction by MI-503 administration or siRNA-mediated silencing of MLL1 attenuated UUO-induced renal fibrosis, and reduced expression of α-smooth muscle actin (α-SMA) and fibronectin. These treatments also inhibited UUO-induced expression of transcription factors Snail and Twist and transforming growth factor β1 (TGF-β1) while expression of E-cadherin was preserved. Moreover, treatment with MI-503 and transfection with either MLL siRNA or menin siRNA inhibited TGF-β1-induced upregulation of α-SMA, fibronectin and Snail, phosphorylation of Smad3 and AKT, and downregulation of E-cadherin in cultured renal epithelial cells. Finally, MI-503 was effective in abrogating serum or TGFβ1-induced transformation of renal interstitial fibroblasts to myofibroblasts in vitro. Taken together, these results suggest that targeting disruption of the MLL1-menin interaction attenuates renal fibrosis through inhibition of partial EMT and renal fibroblast activation.

Practical ethical concerns in allocation of pig kidneys to humans

The fundamental ethical question of whether pig organs should be transplanted into humans has been settled, as recent surgeries demonstrating proof of concept demonstrate. Other issues need to be considered and reconciled before xenotransplantation of pig kidneys becomes a solution to the organ shortage for people waiting for a kidney transplant or as a viable alternative to the deceased donor or living donor human kidneys. Human trials will be needed beyond brain-dead individuals to show that xenotransplantation is safe from immunologic and infectious standpoints. Transplant centers will need to show that xenotransplantation provides a long-term benefit to recipients and is financially viable. If trials are successful and receive regulatory approval, pig xenotransplants may become another option for people waiting for a kidney. Before patients are discharged with a functioning xenograft, practical issues with ethical implications remain.

Inhibition of polycomb repressive complex 2 by targeting EED protects against cisplatin-induced acute kidney injury

Polycomb repressive complex 2 (PRC2) is a multicomponent complex with methyltransferase activity that catalyzes trimethylation of histone H3 at lysine 27 (H3K27me3). Interaction of the epigenetic reader protein EED with EZH2, a catalytic unit of PRC, allosterically stimulates PRC2 activity. In this study, we investigated the role and underlying mechanism of the PRC2 in acute kidney injury (AKI) by using EED226, a highly selective PRC2 inhibitor, to target EED. Administration of EED226 improved renal function, attenuated renal pathological changes, and reduced renal tubular cell apoptosis in a murine model of cisplatin‐induced AKI. In cultured renal epithelial cells, treatment with either EED226 or EED siRNA also ameliorated cisplatin‐induced apoptosis. Mechanistically, EED226 treatment inhibited cisplatin‐induced phosphorylation of p53 and FOXO3a, two transcriptional factors contributing to apoptosis, and preserved expression of Sirtuin 3 and PGC1α, two proteins associated with mitochondrial protection in vivo and in vitro. EED226 was also effective in enhancing renal tubular cell proliferation, suppressing expression of multiple inflammatory cytokines, and reducing infiltration of macrophages to the injured kidney. These data suggest that inhibition of the PRC2 activity by targeting EED can protect against cisplatin‐induced AKI by promoting the survival and proliferation of renal tubular cells and inhibiting inflammatory response.

Efficacy of remdesivir for hospitalized COVID-19 patients with end stage renal disease

BACKGROUND

Since the beginning of corona virus disease 2019 (COVID-19) pandemic, there has been a widespread use of remdesivir in adults and children. There is little known information about its outcomes in patients with end stage renal disease who are on dialysis.

AIM

To assess the clinical outcomes with use of remdesivir in adult patients with end stage kidney failure on hemodialysis.

METHODS

A retrospective, multicenter study was conducted on patients with end stage renal disease on hemodialysis that were discharged after treatment for COVID-19 between April 1, 2020 and December 31, 2020. Primary endpoints were oxygen requirements, time to mortality and escalation of care needing mechanical ventilation.

RESULTS

A total of 45 patients were included in the study. Twenty patients received remdesivir, and 25 patients did not receive remdesivir. Most patients were caucasian, females with diabetes mellitus and hypertension being the commonest comorbidities. There was a trend towards reduced oxygen requirement (beta = -25.93, X² (1) = 6.65, P = 0.0099, probability of requiring mechanical ventilation (beta = -28.52, X² (1) = 22.98, P < 0.0001) and mortality (beta = -5.03, X² (1) = 7.41, P = 0.0065) in patients that received remdesivir compared to the control group.

CONCLUSION

Larger studies are justified to study the effects of remdesivir in this high-risk population with end stage kidney disease on dialysis.

Low-Dose Valganciclovir Prophylaxis Is Safe and Cost-Saving in CMV-Seropositive Kidney Transplant Recipients

Introduction: Observational studies suggest that low-dose valganciclovir prophylaxis (450 mg daily for normal renal function) is as effective as and perhaps safer than standard-dose valganciclovir (900 mg daily) in preventing CMV infection among kidney transplant recipients. However, this practice is not supported by current guidelines due to concerns for breakthrough infection from resistant CMV, mainly in high-risk CMV donor-seropositive/recipient-seronegative kidney transplant recipients. Standard-dose valganciclovir is costly and possibly associated with higher incidence of neutropenia and BKV DNAemia. Our institution adopted low-dose valganciclovir prophylaxis for intermediate-risk (seropositive) kidney transplant recipients in January 2018. Research Question: To analyze the efficacy (CMV DNAemia), safety (BK virus DNAemia, neutropenia, graft loss, and death), and cost savings associated with this change. Design: We retrospectively compared the above outcomes between CMV-seropositive kidney transplant recipients who received low-dose and standard-dose valganciclovir, transplanted within our institution, between 1/19/2014 and 7/15/2019, using propensity score-adjusted competing risk analyses. We also compared cost estimates between the two dosing regimens, for 3 months of prophylaxis, and for different percentage of patient-weeks with normal renal function, using the current average wholesale price of valganciclovir. Results: We studied 179 CMV-seropositive kidney transplant recipients, of whom 55 received low-dose and 124 standard-dose valganciclovir. The majority received nonlymphocyte depleting induction (basiliximab). Low-dose valganciclovir was at least as effective and safe as, and more cost-saving than standard-dose valganciclovir. Conclusion: This single-center study contributes to mounting evidence for future guidelines to be adjusted in favor of low-dose valganciclovir prophylaxis in CMV-seropositive kidney transplant recipients.

New Insights Into the Effects of Individual Chinese Herbal Medicines on Chronic Kidney Disease

The clinical and experimental study into the effects of Chinese herbal medicines on chronic kidney disease has evolved over the past 40 years with new insight into their mechanism and evidence of their clinical effects. Among the many traditional Chinese herbs examined in chronic renal disease, five were found to have evidence of sufficient clinical efficacy, high frequency of use, and well-studied mechanism. They are: Abelmoschus manihot and Huangkui capsule, Salvia miltiorrhiza and its components (tanshinone II A, salvianolic acid A and B); Rhizoma coptidis and its monomer berberine; Tripterygium wilfordii and its components (triptolide, tripterygium glycosides); Kudzu root Pueraria and its monomer Puerarin. These Chinese herbal medications have pharmaceutical effects against fibrosis, inflammation and oxidative stress and also promote renal repair and regeneration. This article reviews their clinical efficacy, anti-fibrotic effects in animal models, and molecular mechanism of action.

Kidney Disease among People Who Are Incarcerated

CKD affects 15% of US adults and is associated with higher morbidity and mortality. CKD disproportionately affects certain populations, including racial and ethnic minorities and individuals from disadvantaged socioeconomic backgrounds. These groups are also disproportionately affected by incarceration and barriers to accessing health services. Incarceration represents an opportunity to link marginalized individuals to CKD care. Despite a legal obligation to provide a community standard of care including the screening and treatment of individuals with CKD, there is little evidence to suggest systematic efforts are in place to address this prevalent, costly, and ultimately fatal condition. This review highlights unrealized opportunities to connect individuals with CKD to care within the criminal justice system and as they transition to the community, and it underscores the need for more evidence-based strategies to address the health effect of CKD on over-represented communities in the criminal justice system.

Critical roles of SMYD2 lysine methyltransferase in mediating renal fibroblast activation and kidney fibrosis

SET and MYND domain protein 2 (SMYD2) is a lysine methyltransferase that mediates histone H3 lysine 36 trimethylation (H3K36me3) and acts as a regulator of tumorgenesis and cystic growth. However, its role in renal fibrosis remains unknown. In this study, we found that SMYD2 was highly expressed in the murine kidney of renal fibrosis induced by unilateral ureteral obstruction, and primarily located in interstitial fibroblasts and renal tubular epithelial cells. Pharmacological inhibition of SMYD2 with AZ505, a highly selective inhibitor of SMYD2, protected against renal fibrosis and inhibited activation/proliferation of renal interstitial fibroblasts and conversion of epithelial cells to a profibrotic phenotype in this model. In cultured renal interstitial fibroblasts, treatment with AZ505 or silencing of SMYD2 by specific siRNA also inhibited serum- or TGF-β1-induced activation and proliferation of renal interstitial fibroblasts. Mechanistic studies showed that SMYD2 inhibition reduced phosphorylation of several profibrotic signaling molecules, including Smad3, extracellular signal-regulated kinase 1/2, AKT, signal transducer and activator of transcription-3 and nuclear factor-κB in both injured kidney and cultured renal fibroblasts. AZ505 was also effective in suppressing renal expression of Snail and Twist, two transcriptional factors that mediate renal partial epithelial-mesenchymal transition and fibrosis. Conversely, AZ505 treatment prevented downregulation of Smad7, a renoprotective factor in vivo and in vitro. These results indicate that SMYD2 plays a critical role in mediating conversion of epithelial cells to a profibrotic phenotype, renal fibroblast activation and renal fibrogenesis, and suggest that SMYD2 may be a potential target for the treatment of chronic fibrosis in kidney disease.

Nephrotoxicity in immune checkpoint inhibitor therapy: a pharmacovigilance study

BACKGROUND

Immune checkpoint inhibitor (ICI) therapy has demonstrated impressive clinical benefits across cancers. However, adverse drug reactions (ADR) occur in every organ system, often due to autoimmune syndromes. We sought to investigate the association between ICI therapy and nephrotoxicity using a pharmacovigilance database, hypothesizing that inflammatory nephrotoxic syndromes, would be reported more frequently in association with ICIs.

METHODS

We analyzed VigiBase, the WHO pharmacovigilance database, to identify renal ADRs (rADRs), such as nephritis, nephropathy, and vascular disorders, reported in association with ICI therapy. We performed a disproportionality analysis to explore if rADRs were reported at a different rate with one of the ICI drugs compared to rADRs in the entire database, using an empirical Bayes estimator as a significance screen and defining the effect size with a reporting odds ratio (ROR).

RESULTS

We found 2,341 rADR for all examined ICI drugs, with a disproportionality signal solely for nephritis (ROR 3.67, 95% CI: 3.34-4.04). Examining the different drugs separately, pembrolizumab, nivolumab, and ipilimumab+nivolumab combination therapy had significantly higher reporting odds of nephritis than the other ICI drugs (ROR 4.54, 95%CI: 3.81-5.4; ROR 3.94, 95%CI: 3.40-4.56; ROR 3.59, 95%CI: 2.71-4.76; respectively).

CONCLUSIONS

Using a pharmacovigilance method, we found increased odds of nephritis when examining renal ADRs associated with ICI therapy. Pembrolizumab, nivolumab, and a combination of ipilimumab plus nivolumab showed the highest odds. Clinicians should consider these findings and be aware of the increased risk of nephritis, especially in patients treated with pembrolizumab, when administering ICI therapy.

Porcine models of acute kidney injury

Pigs represent a potentially attractive model for medical research. Similar body size and physiological patterns of kidney injury that more closely mimic those described in humans make larger animals attractive for experimentation. Using larger animals, including pigs, to investigate the pathogenesis of acute kidney injury (AKI) also serves as an experimental bridge, narrowing the gap between clinical disease and preclinical discoveries. This article compares the advantages and disadvantages of large versus small AKI animal models and provides a comprehensive overview of the development and application of porcine models of AKI induced by clinically relevant insults, including ischemia-reperfusion, sepsis, and nephrotoxin exposure. The primary focus of this review is to evaluate the use of pigs for AKI studies by current investigators, including areas where more information is needed.

Frailty and Kidney Transplantation

Two significant policy changes, one in the way people are put forward for kidney transplants and the other in the way in which kidneys are distributed to people on the waiting list, make the question of whether someone is too frail to receive a transplant all the more relevant, particularly in Rhode Island. An executive order signed by President Donald Trump1 stresses that efforts to treat kidney disease need to concentrate on providing more people with kidney transplants and increasing the number of organs transplanted rather than discarded. An effort to decrease waiting times for kidneys in large metropolitan areas2 potentially means that younger, more desirable kidneys will be shipped out of New England, leaving longer waiting times and less desirable organs for transplantation in our region. The net effect of these changes may mean that potential older or more frail recipients could be faced with accepting kidneys from older or less desirable donors or spend more time on the waiting list and never receive a credible kidney offer. This raises the specter of poor outcomes from marginally functioning kidneys transplanted into marginally functioning recipients or increased rates of death on the waiting list. While organ allocation policies are beyond the ability of transplant nephrologists in Rhode Island to change, we will need to assess patients more closely for signs of frailty and work with referring doctors to reverse frailty when possible so that patients can take advantage of a kidney transplant even if the organ isn't ideal. This article will review the concept of frailty; how to asses it in general and in the context of a transplant evaluation; the risk of frailty in transplant outcomes and the benefits of transplant in reversing frailty; whether markers of frailty can be improved and whether that improves transplant outcomes.

Epidermal Growth Factor Receptor: A Potential Therapeutic Target for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease worldwide and the major cause of renal failure among patients on hemodialysis. Numerous studies have demonstrated that transient activation of epidermal growth factor receptor (EGFR) pathway is required for promoting kidney recovery from acute injury whereas its persistent activation is involved in the progression of various chronic kidney diseases including DKD. EGFR-mediated pathogenesis of DKD is involved in hemodynamic alteration, metabolic disturbance, inflammatory response and parenchymal cellular dysfunction. Therapeutic intervention of this receptor has been available in the oncology setting. Targeting EGFR might also hold a therapeutic potential for DKD. Here we review the functional role of EGFR in the development of DKD, mechanisms involved and the perspective about use of EGFR inhibitors as a treatment for DKD.

Coronavirus Disease 2019 in Kidney Transplant Recipients: Single-Center Experience and Case-Control Study

Background

Kidney transplant recipients (KTR) are considered high-risk for morbidity and mortality from coronavirus disease 2019 (COVID-19). However, some studies did not show worse outcomes compared to non-transplant patients and there is little data about immunosuppressant drug levels and secondary infections in KTR with COVID-19. Herein, we describe our single-center experience with COVID-19 in KTR.

Methods

We captured KTR diagnosed with COVID-19 between March 1, 2020 and May 18, 2020. After exclusion of KTR on hemodialysis and off immunosuppression, we compared the clinical course of COVID-19 between hospitalized KTR and non-transplant patients, matched by age and sex (controls).

Results. Eleven KTR were hospitalized and matched with 44 controls. One KTR and 4 controls died (case fatality rate: 9.1%). There were no significant differences in length of stay or clinical outcomes between KTR and controls. Tacrolimus or sirolimus levels were >10 ng/mL in 6 out of 9 KTR (67%). Bacterial infections were more frequent in KTR (36.3%), compared with controls (6.8%, P = .02).

Conclusions

In our small case series, unlike earlier reports from the pandemic epicenters, the clinical outcomes of KTR with COVID-19 were comparable to those of non-transplant patients. Calcineurin or mammalian target of rapamycin inhibitor (mTOR) levels were high. Bacterial infections were more common in KTR, compared with controls.

Histone demethylase JMJD3 protects against renal fibrosis by suppressing TGFβ and Notch signaling and preserving PTEN expression

Rationale: The Jumonji domain containing-3 (JMJD3), a specific histone demethylase for trimethylation on histone H3 lysine 27 (H3K27me3), is associated with the pathogenesis of many diseases, but its role in renal fibrosis remains unexplored. Here we examined the role of JMJD3 and mechanisms involved in the activation of renal fibroblasts and development of renal fibrosis.

Methods: Murine models of 5/6 surgical nephrectomy (SNx) and ureteral unilateral obstruction (UUO) were used to assess the effect of a specific JMJD3 inhibitor, GSKJ4, and genetic deletion of JMJD3 from FOXD1 stroma-derived renal interstitial cells on the development of renal fibrosis and activation of renal interstitial fibroblasts. Cultured rat renal interstitial fibroblasts (NRK-49F) and mouse renal tubular epithelial cells (mTECs) were also used to examine JMJD3-mediated activation of profibrotic signaling.

Results: JMJD3 and H3K27me3 expression levels were upregulated in the kidney of mice subjected to SNx 5/6 and UUO. Pharmacological inhibition of JMJD3 with GSKJ4 or genetic deletion of JMJD3 led to worsening of renal dysfunction as well as increased deposition of extracellular matrix proteins and activation of renal interstitial fibroblasts in the injured kidney. This was coincident with decreased expression of Smad7 and enhanced expression of H3K27me3, transforming growth factor β1 (TGFβ1), Smad3, Notch1, Notch3 and Jagged1. Inhibition of JMJD3 by GSK J4 or its specific siRNA also resulted in the similar responses in cultured NRK-49F and mTECs exposed to serum or TGFβ1. Moreover, JMJD3 inhibition augmented phosphorylation of AKT and ERK1/2 in vivo and in vitro.

Conclusion: These results indicate that JMJD3 confers anti-fibrotic effects by limiting activation of multiple profibrotic signaling pathways and suggest that JMJD3 modulation may have therapeutic effects for chronic kidney disease.

530. COVID-19 in kidney transplant recipients: Single-center experience and case-control study

Background

Organ transplant recipients (OTR) are considered high-risk for morbidity and mortality from COVID-19. Case-fatality rates (CFR) vary significantly in different case series, and some patients were still hospitalized at the time of analyses. To our knowledge, no case-control study of COVID-19 in OTR has been published to-date.

Methods

We captured kidney transplant recipients (KTR) diagnosed with COVID-19 between 3/1 and 5/18/2020. After exclusion of KTR on hemodialysis and off immunosuppression (IS), we compared the clinical course of COVID-19 between hospitalized KTR and non-transplant patients, matched by sex and age (controls). All patients were discharged from the hospital or died.

Results

16 KTR had COVID-19. All 3 KTR off IS, who were excluded from further analyses, survived. Median age was 54 (range: 34–65) years; 5/13 KTR (38.4%) were men. Median time from transplant was 41 (range: 1–203) months. Two KTR, both transplanted >10 years ago, were managed as outpatients. IS was reduced in 12/13 (92.3%), most often by discontinuation of the antimetabolite. IL6 levels were >1,000 (normal: < 5) pg/mL in 3 KTR. Tacrolimus or sirolimus levels were >10 ng/mL in 6/9 KTR (67%) (Table 1). Eleven KTR were hospitalized (84.6%) and matched with 44 controls. One KTR, the only one treated with hydroxychloroquine, died (CFR 5.8%; 7.6% in KTR on IS; 9% in hospitalized KTR on IS). Four controls died (CFR: 9%; state CFR: 5.2%; inpatient CFR: 16.6%). There were no significant differences in length of stay or worst oxygenation status between hospitalized KTR and controls. Four KTR (30.7%), received remdesivir, 4 convalescent plasma, 3 (23%) tocilizumab. KTR received more often broad-spectrum antibiotics, convalescent plasma or tocilizumab, compared to controls (Table 2).

Table 1

Table 2

Conclusion

Unlike early reports from the pandemic epicenters, the clinical course and outcomes of KTR with COVID-19 in our small case series were comparable to those of non-transplant patients. Calcineurin or mTOR inhibitor levels were high, likely due to diarrhea and COVID-19-related hepatic dysfunction. Extremely high IL6 levels were common. The role of IS and potential benefits from investigational treatments remain to be elucidated. A larger multi-institutional study is underway.

Disclosures

All Authors: No reported disclosures

576. Half-dose Valganciclovir Prophylaxis is Safe and Cost-effective in CMV Seropositive Renal Transplant Recipients

Background

Observational studies suggest that half-dose valganciclovir (VGV) prophylaxis (450 mg daily for normal renal function) is as effective as full-dose (900 mg daily) in preventing CMV infection among kidney transplant recipients (KTR). However, this practice is not supported by current guidelines, for fear of selecting resistance, mainly in high-risk, i.e. donor CMV seropositive/recipient negative (D+/R-) KTR. Full-dose VGV is costly, and possibly associated with higher incidence of neutropenia and BK viremia. Our institution adopted half-dose VGV prophylaxis for R+ KTR in January 2018.

Methods

We included R+ KTR transplanted between 1/1/2014 and 12/31/2018 at our center. Data were censored at 1-year post-transplant, graft loss or death. Primary outcomes were early (&lt; 6 months from transplant) and any CMV viremia. Secondary outcomes were neutropenia, BK viremia, graft loss and death. Categorical variables were compared with χ 2 or Fisher’s exact tests, continuous variables with the Mann-Whitney test. We used log-rank and Gray’s tests to compare cumulative incidence of outcomes, after adjustment by propensity score for differences in baseline characteristics.

Results

106 R+ KTR received full-dose and 35 half-dose VGV. Antithymocyte globulin (ATG) induction was associated with significantly higher cumulative incidence of both early (P=0.017) and any (P=0.02) CMV viremia, compared to basiliximab induction (Fig. 1). After adjusting for gender and induction regimen, we noted a signal for higher cumulative incidence of any (P=0.044), but not early (P=0.598) CMV viremia in the full-dose VGV group (Fig. 2). There were no significant differences (P &gt;0.1) in incidence of neutropenia, BK viremia, graft loss or death between the two groups. Cost savings were estimated at $2630 per CMV R+ KTR (Table 1).

Table 1. Comparison of outcomes and cost between the two anti-CMV prophylaxis groups. Data are presented as n (%), unless otherwise indicated.

Conclusion

In our pilot series, half-dose VGV was at least as effective as full-dose VGV in preventing CMV viremia in R+ RTR, and less costly. If larger scale studies verify generalizability of these results, half-dose VGV may be considered as standard of care for R+ KTR. In KTR, the antimetabolite probably contributes to neutropenia more than VGV prophylaxis.

Disclosures

All Authors: No reported disclosures

Inpatient Dialysis Planning During the COVID-19 Pandemic: A Single-Center Experience and Review of the Literature

BACKGROUND

COVID-19 has created havoc in healthcare systems worldwide, including shortages in equipment and supplies for dialysis in the acute setting.

METHODS

We compared our planning and experience at a tertiary care academic medical center to recommendations in the literature.

RESULTS

Published literature and our experience underscored the need to plan for adequate dialysis equipment, particularly for continuous renal replacement therapy in the ICU setting, adequate nursing, and flexible scheduling of chronic patients to accommodate the surge in acute patients. We discovered other "shortages" not mentioned in the literature: shortages in the number of portable reverse osmosis (RO) machines needed to prepare dialysis water, inadequate number of rooms in units designated for COVID-19 patients with plumbing for dialysis, and lack of temperature blending valves on sinks that necessitated using cold water only, and damaging the RO membranes. We identified the need for cooperation between nephrology and critical care medicine, hospital-based and community nephrologists and community dialysis units as well as nephrologists at other hospitals in the region. We turned to guidance from the hospital ethics committee.

CONCLUSION

Planning for an expected surge in hospitalized patients requiring RRT demands coordination between critical care, dialysis and nursing services as well as community and hospital providers to make certain there are adequate dialysis resources. Our experience suggests that continuous dialysis is in greatest demand early in the illness, and that plans to increase supplies should be put in place. But, planning should also focus on unforeseen hospital-specific infrastructure shortages that can develop over time and hamper intermittent dialysis delivery to all patients who require treatment.

Class IIa HDAC inhibitor TMP195 alleviates lipopolysaccharide-induced acute kidney injury

Sepsis-associated acute kidney injury (SA-AKI) is associated with high mortality rates, but clinicians lack effective treatments except supportive care or renal replacement therapies. Recently, histone deacetylase (HDAC) inhibitors have been recognized as potential treatments for acute kidney injury and sepsis in animal models; however, the adverse effect generated by the use of pan inhibitors of HDACs may limit their application in people. In the present study, we explored the possible renoprotective effect of a selective class IIa HDAC inhibitor, TMP195, in a murine model of SA-AKI induced by lipopolysaccharide (LPS). Administration of TMP195 significantly reduced increased serum creatinine and blood urea nitrogen levels and renal damage induced by LPS; this was coincident with reduced expression of HDAC4, a major isoform of class IIa HDACs, and elevated histone H3 acetylation. TMP195 treatment following LPS exposure also reduced renal tubular cell apoptosis and attenuated renal expression of neutrophil gelatinase-associated lipocalin and kidney injury molecule-1, two biomarkers of tubular injury. Moreover, LPS exposure resulted in increased expression of BAX and cleaved caspase-3 and decreased expression of Bcl-2 and bone morphogenetic protein-7 in vivo and in vitro; TMP195 treatment reversed these responses. Finally, TMP195 inhibited LPS-induced upregulation of multiple proinflammatory cytokines/chemokines, including intercellular adhesion molecule-1, monocyte chemoattractant protein-1, tumor necrosis factor-α, and interleukin-1β, and accumulation of inflammatory cells in the injured kidney. Collectively, these data indicate that TMP195 has a powerful renoprotective effect in SA-AKI by mitigating renal tubular cell apoptosis and inflammation and suggest that targeting class IIa HDACs might be a novel therapeutic strategy for the treatment of SA-AKI that avoids the unintended adverse effects of a pan-HDAC inhibitor.

Successful recovery from COVID-19 in three kidney transplant recipients who received convalescent plasma therapy

Novel coronavirus disease 2019 (COVID‐19) is a highly infectious, rapidly spreading viral disease that typically presents with greater severity in patients with underlying medical conditions or those who are immunosuppressed. We present a novel case series of three kidney transplant recipients with COVID‐19 who recovered after receiving COVID‐19 convalescent plasma (CCP) therapy. Physicians should be aware of this potentially useful treatment option. Larger clinical registries and randomized clinical trials should be conducted to further explore the clinical and allograft outcomes associated with CCP use in this population.

Identification of histone deacetylase 8 as a novel therapeutic target for renal fibrosis

Histone deacetylases (HDACs) have been shown to alleviate renal fibrosis, however, the role of individual HDAC isoforms in this process is poorly understood. In this study, we examined the role of HDAC8 in the development of renal fibrosis and partial epithelial-mesenchymal transitions (EMT). In a murine model of renal fibrosis induced by unilateral ureteral obstruction (UUO), HDAC8 was primarily expressed in renal tubular epithelial cells and time-dependently upregulated. This occurred in parallel with the deacetylation of cortactin, a nonhistone substrate of HDAC8, and increased expression of three fibrotic markers: α-smooth muscle actin, collagen 1, and fibronectin. Administration of PCI34051, a highly selective inhibitor of HDAC8, restored acetylation of contactin and reduced expression of those proteins. PCI34051 treatment also reduced the number of renal tubular epithelial cells arrested at the G2/M phase of the cell cycle and suppressed phosphorylation of Smad3, STAT3, β-catenin, and expression of Snail after ureteral obstruction. In contrast, HDAC8 inhibition reversed UUO-induced downregulation of BMP7 and Klotho, two renoprotective proteins. In cultured murine proximal tubular cells, treatment with PCI34051 or specific HDAC8 siRNA was also effective in inhibiting transforming growth factor β1 (TGFβ1)-induced deacetylation of contactin, EMT, phosphorylation of Smad3, STAT3, and β-catenin, upregulation of Snail, and downregulation of BMP7 and Klotho. Collectively, these results suggest that HDAC8 activation is required for the EMT and renal fibrogenesis by activation of multiple profibrotic signaling and transcription factors, and suppression of antifibrotic proteins. Therefore, targeting HDAC8 may be novel therapeutic approach for treatment of renal fibrosis.

Blocking the histone lysine 79 methyltransferase DOT1L alleviates renal fibrosis through inhibition of renal fibroblast activation and epithelial-mesenchymal transition

Disruptor of telomeric silencing-1 like (DOT1L) protein specifically catalyzes the methylation of histone H3 on Lys79 (H3K79) and is implicated in tumors. But its role in tissue fibrosis remains unclear. Here we demonstrated that injury to the kidney increased DOT1L expression and H3K79 dimethylation in renal tubular epithelial cells and myofibroblasts in a murine model of unilateral ureteral obstruction. Administration of EPZ5676, a highly selective inhibitor of DOT1L, attenuated renal fibrosis. Treatment with EPZ5676 or DOT1L small interfering RNA also inhibited TGF-β1 and serum-induced activation of renal interstitial fibroblasts and epithelial-mesenchymal transition (EMT) in vitro. Moreover, blocking DOT1L abrogated injury-induced epithelial G₂/M arrest; reduced expression of Snail, Twist, and Notch1; and inactivated several profibrotic signaling molecules in the injured kidney, including Smad3, epidermal growth factor receptor, platelet-derived growth factor receptor, signal transducer and activator of transcription 3, protein kinase B, and NF-κB. Conversely, DOT1L inhibition increased expression of phosphatase and tensin homolog, a protein associated with dephosphorylation of tyrosine kinase receptors, and prevented decline in levels of Klotho and Smad7, 2 renoprotective factors. Thus, our data indicate that targeting DOT1L attenuates renal fibrosis through inhibition of renal fibroblasts and EMT by suppressing activation of multiple profibrotic signaling pathways while retaining expression of renoprotective factors.-Liu, L., Zou, J., Guan, Y., Zhang, Y., Zhang, W., Zhou, X., Xiong, C., Tolbert, E., Zhao, T. C., Bayliss, G., Zhuang, S. Blocking the histone lysine 79 methyltransferase DOT1L alleviates renal fibrosis through inhibition of renal fibroblast activation and epithelial-mesenchymal transition.

Application of nintedanib and other potential anti-fibrotic agents in fibrotic diseases

Nintedanib, a Food and Drug Administration-approved drug for the treatment of patients with idiopathic pulmonary fibrosis (IPK), inhibits both tyrosine kinase receptors and non-receptor kinases, and block activation of platelet-derived growth factor receptors, fibroblast growth factor receptor, vascular endothelial growth factor receptors, and Src family kinases. Preclinical and clinical studies have revealed the potent anti-fibrotic effect of nintedanib in IPK in human and animal models. Recent preclinical studies have also demonstrated the inhibitory effect of nintedanib on the development and progression of tissue fibrosis in other organs, including liver, kidney, and skin. The anti-fibrotic actions of nintedanib occur through a number of mechanisms, including blocking differentiation of fibroblasts to myofibroblasts, inhibition of epithelial-mesenchymal transition, and suppression of inflammation and angiogenesis. In this article, we summarize the mechanisms and efficacy of nintedanib in the treatment of fibrotic diseases in animal models and clinical trials, provide an update on recent advances in the development of other novel antifibrotic agents in preclinical and clinical study, and offer our perspective about the possible clinical application of these agents in fibrotic diseases.

Selective inhibition of class IIa histone deacetylases alleviates renal fibrosis

In this study, we examined the effect of MC1568, a selective class IIa histone deacetylase (HDAC) inhibitor, on the development and progression of renal fibrosis in a murine model of renal fibrosis induced by unilateral ureteral obstruction (UUO). All 4 class IIa HDAC isoforms, in particular HDAC4, were up-regulated in renal epithelial cells of the injured kidney. Administration of MC1568 immediately after UUO injury reduced expression of α-smooth muscle actin (α-SMA), fibronectin, and collagen 1. MC1568 treatment or small interfering RNA-mediated silencing of HDAC4 also suppressed expression of those proteins in cultured renal epithelial cells. Mechanistically, MC1568 abrogated UUO-induced phosphorylation of Smad3, NF-κB, and up-regulation of integrin ɑVβ6 in the kidney and inhibited TGF-β1-induced responses in cultured renal epithelial cells. MC1568 also increased renal expression of klotho, bone morphogenetic protein 7, and Smad7. Moreover, delayed administration of MC1568 at 3 d after ureteral obstruction reversed the expression of α-SMA, fibronectin, and collagen 1 and increased expression of matrix metalloproteinase (MMP)-2 and -9. Collectively, these results suggest that selectively targeting class IIa HDAC isoforms (in particular HDAC4) may inhibit development and progression of renal fibrosis by suppressing activation and expression of multiple profibrotic molecules and increasing expression of antifibrotic proteins and MMPs.-Xiong, C., Guan, Y., Zhou, X., Liu, L., Zhuang, M. A., Zhang, W., Zhang, Y., Masucci, M. V., Bayliss, G., Zhao, T. C., Zhuang, S. Selective inhibition of class IIa histone deacetylases alleviates renal fibrosis.

Targeting Regulatory T Cells for Transplant Tolerance: New Insights and Future Perspectives

Background

Organ transplantation is considered the ultimate therapy for end-stage organ disease. While pharmacologic immunosuppression is the mainstay of therapeutic strategies to prolong the survival of the graft, long-term use of immunosuppressive medications carries the risk of organ toxicity, malignancies, serious opportunistic infections, and diabetes. Therapies that promote recipient tolerance in solid organ transplantation are able to improve patient outcomes by eliminating the need for long-term immunosuppression.

Summary

Establishing tolerance to an allograft has become an area of intense study and would be the ideal therapy in clinical practice. The discovery of a subset of T cells naturally committed to perform immunoregulation has led to further investigation into their role in the immunopathogenesis of transplantation. Evidence suggests that regulatory T cells (Tregs) are fundamentally involved in promoting allograft tolerance. Efforts to characterize specific markers for Tregs, while challenging, have identified Foxp3 gene expression as a crucial step in promoting the tolerance-inducing features of Tregs. A number of approaches, including those based on targeting the glycogen synthase kinase 3β signaling pathway or activating the melanocortinergic pathway, have been tested as a way to promote Treg lineage commitment and maintenance as well as to facilitate immune tolerance. In order to be effective in clinical practice, Tregs must be allospecific and possess a specific phenotype to avoid suppression of other aspects of the immune system or increasing the risk of malignancy or infections. Multiple experimental and clinical studies have demonstrated the impact of currently used immunosuppressants on the immunoregulatory activities of Tregs and their Foxp3 expression status. Pharmacological induction of tolerogenic Tregs for inducing transplant tolerance, including epigenetic therapies, is in the ascendant.

Key Messages

Therapies that promote Treg function and survival may represent a novel strategy for achieving immune tolerance in transplant patients.

Targeting histone methyltransferase enhancer of zeste homolog-2 inhibits renal epithelial-mesenchymal transition and attenuates renal fibrosis

Enhancer of zeste homolog-2 (EZH2) is a methyltransferase that induces histone H3 lysine 27 trimethylation (H3K27me3) and functions as an oncogenic factor in many cancer types. Its role in renal epithelial-mesenchymal transition (EMT) remains unknown. In this study, we found that EZH2 and H3K27me3 were highly expressed in mouse kidney with unilateral ureteral obstruction and cultured mouse kidney proximal tubular (TKPT) cells undergoing EMT. Inhibition of EZH2 with 3-deazaneplanocin A (3-DZNeP) attenuated renal fibrosis, which was associated with preserving E-cadherin expression and inhibiting Vimentin up-regulation in the obstructed kidney. Treatment with 3-DZNeP or transfection of EZH2 siRNA also inhibited TGF-β1-induced EMT of TKPT cells. Injury to the kidney or cultured TKPT cells resulted in up-regulation of Snail-l family transcriptional repressor (Snail)-1 and Twist family basic helix-loop-helix (BHLH) transcription factor (Twist)-1, which are 2 transcription factors, and down-regulation of phosphatase and tensin homolog, a protein tyrosine phosphatase associated with inhibition of PI3K-protein kinase B (AKT) signaling; EZH2 inhibition or silencing reversed all those responses. 3-DZNeP was also effective in suppressing epithelial arrest at the G2/M phase and dephosphorylating AKT and β-catenin in vivo and in vitro. These data indicate that EZH2 activation contributes to renal EMT and fibrosis through activation of multiple signaling pathways and suggest that EZH2 has potential as a therapeutic target for treatment of renal fibrosis.-Zhou, X., Xiong, C., Tolbert, E., Zhao, T. C., Bayliss, G., Zhuang, S. Targeting histone methyltransferase enhancer of zeste homolog-2 inhibits renal epithelial-mesenchymal transition and attenuates renal fibrosis.

Pharmacological inhibition of Src kinase protects against acute kidney injury in a murine model of renal ischemia/reperfusion

Activation of Src kinase has been implicated in the pathogenesis of acute brain, liver, and lung injury. However, the role of Src in acute kidney injury (AKI) remains unestablished. To address this, we evaluated the effects of Src inhibition on renal dysfunction and pathological changes in a murine model of AKI induced by ischemia/reperfusion (I/R). I/R injury to the kidney resulted in increased Src phosphorylation at tyrosine 416 (activation). Administration of PP1, a highly selective Src inhibitor, blocked Src phosphorylation, improved renal function and ameliorated renal pathological damage. PP1 treatment also suppressed renal expression of neutrophil gelatinase-associated lipocalin and reduced apoptosis in the injured kidney. Moreover, Src inhibition prevented downregulation of several adherens and tight junction proteins, including E-cadherin, ZO-1, and claudins-1/−4 in the kidney after I/R injury as well as in cultured renal proximal tubular cells following oxidative stress. Finally, PP1 inhibited I/R–induced renal expression of matrix metalloproteinase-2 and -9, phosphorylation of extracellular signal–regulated kinases1/2, signal transducer and activator of transcription-3, and nuclear factor-κB, and the infiltration of macrophages into the kidney. These data indicate that Src is a pivotal mediator of renal epithelial injury and that its inhibition may have a therapeutic potential to treat AKI.

Cholesterol Crystal Embolism and Chronic Kidney Disease

Renal disease caused by cholesterol crystal embolism (CCE) occurs when cholesterol crystals become lodged in small renal arteries after small pieces of atheromatous plaques break off from the aorta or renal arteries and shower the downstream vascular bed. CCE is a multisystemic disease but kidneys are particularly vulnerable to atheroembolic disease, which can cause an acute, subacute, or chronic decline in renal function. This life-threatening disease may be underdiagnosed and overlooked as a cause of chronic kidney disease (CKD) among patients with advanced atherosclerosis. CCE can result from vascular surgery, angiography, or administration of anticoagulants. Atheroembolic renal disease has various clinical features that resemble those found in other kidney disorders and systemic diseases. It is commonly misdiagnosed in clinic, but confirmed by characteristic renal biopsy findings. Therapeutic options are limited, and prognosis is considered to be poor. Expanding knowledge of atheroembolic renal disease due to CCE opens perspectives for recognition, diagnosis, and treatment of this cause of progressive renal insufficiency.

Proliferative glomerulonephritis with monoclonal IgG deposits in two kidney allografts successfully treated with rituximab

Proliferative glomerulonephritis with monoclonal immunoglobulin G deposit (PGNMID), a recently described pathologic entity in native kidneys, has been recognized in kidney transplant patients, where it can present as either recurrent or de novo disease. There is no definitive treatment to date, in either population. Here, we present two cases of PGNMID in kidney allografts that illustrate the challenges of diagnostic approach and highlight the allograft outcome after treatment with rituximab as a potential treatment of this condition.

Renal Function Alters Antihypertensive Regimens in Type 2 Diabetic Patients

To determine the prevalence of multidrug antihypertensive therapy (MDAT), records were evaluated for patients with both type 2 diabetes and hypertension during a 5-year period at Joslin Diabetes Center. Hypertension control was defined as requiring multiple drugs if three or more antihypertensive drugs were used, one of which must be a diuretic (unless patient is receiving dialysis), or use of four or more antihypertensive drugs, one of which a diuretic (unless patient is receiving dialysis) was established. The objective was to determine the prevalence of multidrug requirement for hypertensive therapy in relationship to four levels of renal function estimated by the Modification of Diet in Renal Disease formula for glomerular filtration rate (GFR). Among 10,151 patients, mean estimated GFR was 80 mL/min. Using standard (ASN) classification for renal function, we noted the following breakdown of MDAT use: Estimated GFR Drugs, Mean No. ≥3 Drugs, No. (%) ≥4 Drugs, No. (%) <30 3.1 379 (67) 214 (38) 30-60 2.7 1233 (55) 538 (24) 60-90 2.0 1279 (33) 458 (12) >90 1.5 600 (17) 185 (5) Prevalence of multidrug antihypertensive therapy is markedly increased in the presence of reduced renal function.

Cardiovascular-renal complications and the possible role of plasminogen activator inhibitor: a review

Since angiotensin increases the expression of plasminogen activator inhibitor (PAI), mechanisms associated with an actively functioning renin–angiotensin–aldosterone system can be expected to be associated with increased PAI-1 expression. These mechanisms are present not only in common conditions resulting in glomerulosclerosis associated with aging, diabetes or genetic mutations, but also in autoimmune disease (like scleroderma and lupus), radiation injury, cyclosporine toxicity, allograft nephropathy and ureteral obstruction. While the renin–angiotensin–aldosterone system and growth factors, such as transforming growth factor-beta (TGF-β), are almost always part of the process, there are rare experimental observations of PAI-1 expression without their interaction. Here we review the literature on PAI-1 and its role in vascular, fibrotic and oxidative injury as well as work suggesting potential areas of intervention in the pathogenesis of multiple disorders.

Role for urinary biomarkers in diagnosis of acute rejection in the transplanted kidney

Despite the introduction of potent immunosuppressive medications within recent decades, acute rejection still accounts for up to 12% of all graft losses, and is generally associated with an increased risk of late graft failure. Current detection of acute rejection relies on frequent monitoring of the serum creatinine followed by a diagnostic renal biopsy. This strategy is flawed since an alteration in the serum creatinine is a late clinical event and significant irreversible histologic damage has often already occurred. Furthermore, biopsies are invasive procedures that carry their own inherent risk. The discovery of non-invasive urinary biomarkers to help diagnose acute rejection has been the subject of a significant amount of investigation. We review the literature on urinary biomarkers here, focusing on specific markers perforin and granzyme B mRNAs, FOXP3 mRNA, CXCL9/CXCL10 and miRNAs. These and other biomarkers are not yet widely used in clinical settings, but our review of the literature suggests that biomarkers may correlate with biopsy findings and provide an important early indicator of rejection, allowing more rapid treatment and better graft survival.

Enhancer of Zeste Homolog 2 Inhibition Attenuates Renal Fibrosis by Maintaining Smad7 and Phosphatase and Tensin Homolog Expression

Enhancer of zeste homolog 2 (EZH2) is a methyltransferase that induces histone H3 lysine 27 trimethylation (H3K27me3) and functions as an oncogenic factor in many cancer types. However, the role of EZH2 in renal fibrogenesis remains unexplored. In this study, we found high expression of EZH2 and H3K27me3 in cultured renal fibroblasts and fibrotic kidneys from mice with unilateral ureteral obstruction and humans with CKD. Pharmacologic inhibition of EZH2 with 3-deazaneplanocin A (3-DZNeP) or GSK126 or siRNA-mediated silencing of EZH2 inhibited serum- and TGFβ1-induced activation of renal interstitial fibroblasts in vitro, and 3-DZNeP administration abrogated deposition of extracellular matrix proteins and expression of α-smooth muscle actin in the obstructed kidney. Injury to the kidney enhanced Smad7 degradation, Smad3 phosphorylation, and TGFβ receptor 1 expression, and 3-DZNeP administration prevented these effects. 3-DZNeP also suppressed phosphorylation of the renal EGF and PDGFβ receptors and downstream signaling molecules signal transducer and activator of transcription 3 and extracellular signal-regulated kinase 1/2 after injury. Moreover, EZH2 inhibition increased the expression of phosphatase and tensin homolog (PTEN), a protein previously associated with dephosphorylation of tyrosine kinase receptors in the injured kidney and serum-stimulated renal interstitial fibroblasts. Finally, blocking PTEN with SF1670 largely diminished the inhibitory effect of 3-DZNeP on renal myofibroblast activation. These results uncovered the important role of EZH2 in mediating the development of renal fibrosis by downregulating expression of Smad7 and PTEN, thus activating profibrotic signaling pathways. Targeted inhibition of EZH2, therefore, could be a novel therapy for treating CKD.

Activation of Sirtuin-1 Promotes Renal Fibroblast Activation and Aggravates Renal Fibrogenesis

Although activation of sirtuin-1 (SIRT1) has been shown to protect the kidney from acute injury, its role in renal fibrosis remains controversial since both inhibition and activation of SIRT1 have been reported to attenuate renal fibrosis. To resolve this conflict, we further examined the effect of SIRT1 activators on the activation of renal interstitial fibroblasts and development of renal fibrosis in vivo and in vitro. In a murine model of renal fibrosis induced by unilateral ureteral obstruction, administration of SRT1720 (N-[2-[3-(piperazin-1-ylmethyl)imidazo[2,1-b][1,3]thiazol-6-yl]phenyl]quinoxaline-2-carboxamide), a potent activator of SIRT1, accelerated deposition of collagen fibrils and increased expression of fibroblast activation markers (α-smooth muscle actin [α-SMA], collagen I, and fibronectin) in the obstructive kidney of mice. In cultured rat renal interstitial fibroblasts (NRK-49F), exposure of cells to SRT1720 or YK-3-237 (B-[2-methoxy-5-[(1E)-3-oxo-3-(3,4,5-trimethoxyphenyl)-1-propen-1-yl]phenyl]-boronic acid), another SIRT1 activator, also resulted in enhanced expression of α-SMA and fibronectin. Mechanistic studies showed that augmentation of renal fibrogenesis by SRT1720 is associated with elevated phosphorylation of epidermal growth factor receptor (EGFR) and platelet-derived growth factor receptor β (PDGFRβ). SRT1720 treatment also increased the phosphorylation of signal transducer and activator of transcription 3 and protein kinase B in the fibrotic kidney and NRK-49F cells. However, SRT1720 treatment did not affect expression of proliferating cell nuclear protein, a proliferation marker and activation of extracellular signal regulated kinase 1/2 in vitro and in vivo. These results indicate that SIRT1-activating compounds can provoke renal fibrogenesis through a mechanism involved in the activation of EGFR and PDGFR signaling pathways and suggest that long-term use of SIRT1 activators risks the development and progression of chronic kidney disease.

P2X7 receptor inhibition protects against ischemic acute kidney injury in mice

Activation of the purinergic P2X7 receptor (P2X7R) has been associated with the development of experimental nephritis and diabetic and hypertensive nephropathy. However, its role in acute kidney injury (AKI) remains unknown. In this study, we examined the effects of P2X7R inhibition in a murine model of ischemia-reperfusion (I/R)-induced AKI using A438079, a selective inhibitor of P2X7R. At 24 h after I/R, mice developed renal dysfunction and renal tubular damage, which was accompanied by elevated expression of P2X7R. Early administration of A438079 immediately or 6 h after the onset of reperfusion protected against renal dysfunction and attenuated kidney damage whereas delayed administration of A438079 at 24 h after restoration of perfusion had no protective effects. The protective actions of A438079 were associated with inhibition of renal tubule injury and cell death and suppression of renal expression of monocyte chemotactic protein-1 and regulated upon expression normal T cell expressed and secreted (RANTES). Moreover, I/R injury led to an increase in phosphorylation (activation) of extracellular signal-regulated kinases 1/2 in the kidney; treatment with A438079 diminished this response. Collectively, these results indicate that early P2X7R inhibition is effective against renal tubule injury and proinflammatory response after I/R injury and suggest that targeting P2X7R may be a promising therapeutic strategy for treatment of AKI.

Resistant hypertension in diabetes mellitus

Resistant hypertension in diabetes is associated with poor cardiovascular and renal outcomes. This brief review will examine the definitions and epidemiology of resistant hypertension and consider the differences between apparent resistant hypertension and truly resistant or refractory hypertension. It will review the role of the sympathetic nervous system in resistant hypertension. It will consider the relationship between obesity and leptin resistance and sympathetic signaling; the role of obstructive sleep apnea in resistant hypertension; and the role of aldosterone in resistant hypertension. It will conclude by mentioning briefly renal nerve ablation.

Class I HDAC activity is required for renal protection and regeneration after acute kidney injury

Activation of histone deacetylases (HDACs) is required for renal epithelial cell proliferation and kidney development. However, their role in renal tubular cell survival and regeneration after acute kidney injury (AKI) remains unclear. In this study, we demonstrated that all class I HDAC isoforms (1, 2, 3, and 8) were expressed in the renal epithelial cells of the mouse kidney. Inhibition of class I HDACs with MS-275, a highly selective inhibitor, resulted in more severe tubular injury in the mouse model of AKI induced by folic acid or rhabdomyolysis, as indicated by worsening renal dysfunction, increased neutrophil gelatinase-associated lipocalin expression, and enhanced apoptosis and caspase-3 activation. Blocking class I HDAC activity also impaired renal regeneration as evidenced by decreased expression of renal Pax-2, vimentin, and proliferating cell nuclear antigen. Injury to the kidney is accompanied by increased phosphorylation of epidermal growth factor receptor (EGFR), signal transducers and activators of transcription 3 (STAT3), and Akt. Inhibition of class I HDACs suppressed EGFR phosphorylation as well as reduced its expression. MS-275 was also effective in inhibiting STAT3 and Akt phosphorylation, but this treatment did not affect their expression levels. Taken together, these data suggest that the class I HDAC activity contributes to renal protection and functional recovery and is required for renal regeneration after AKI. Furthermore, renal EGFR signaling is subject to regulation by this class of HDACs.

Initiation of dialysis: a mini-review of a changing paradigm

A paradigm shift is occurring in the way nephrologists evaluate patients with progressive chronic kidney disease for initiation of maintenance renal replacement therapy. Serum creatinine and serum creatinine-based equations used to calculate an estimated glomerular filtration rate (eGFR) are not accurate approximations of renal function at low levels. Further complicating matters is a trend toward early initiation of dialysis, once considered beneficial since patients had better outcomes if they started dialysis before the onset of protein malnutrition. But recent data, including results of a large randomized controlled trial, suggest no benefit and possibly increased risk of death with early initiation of dialysis. This review will examine the data and where the field stands in deciding when to initiate dialysis.

Class I histone deacetylase activity is required for proliferation of renal epithelial cells

The process of renal regeneration after acute kidney injury is thought to recapitulate renal development, and proliferation of renal proximal tubular cells (RPTCs) is a critical step in the regenerative response. Recent studies indicate that class I histone deacetylases (HDACs) are required for embryonic kidney gene expression, growth, and differentiation. The role and underlying mechanisms of class I HDAC activation in RPTC proliferation, however, remain unclear. In this study, we used cultured RPTCs to examine this issue since four class I HDAC isoforms (1, 2, 3, and 8) are abundantly expressed in this cell type. Blocking class I HDAC activity with a highly selective inhibitor, MS-275, induced global histone H3 hyperacetylation, reduced RPTC proliferation, and diminished expression of cyclin D1 and proliferating cell nuclear antigen. Silencing HDAC1, 3, or 8 with small interfering RNA resulted in similar biological effects. Activation of epidermal growth factor receptor (EGFR) and signal transducers and activators of transcription 3 (STAT3) was required for RPTC proliferation, and STAT3 functioned downstream of EGFR. Treatment with MS-275 or knockdown of HDAC1, 3, or 8 suppressed EGFR expression and phosphorylation, and silencing HDAC1 and 3 also reduced STAT3 phosphorylation. However, HDAC2 downregulation did not affect RPTC proliferation and phosphorylation of EGFR and STAT3. Collectively, these data reveal a critical role of class I HDACs in mediating proliferation of renal epithelial cells through activation of the EGFR/STAT3 signaling pathway.

Sustained activation of EGFR triggers renal fibrogenesis after acute kidney injury

Severe acute kidney injury (AKI) is frequently accompanied by maladaptive repair and renal fibrogenesis; however, the molecular mechanisms that mediate these acute and chronic consequences of AKI remain poorly understood. In this study, we examined the role of epidermal growth factor receptor (EGFR) in these processes using waved-2 (Wa-2) mice, which have reduced EGFR activity, and their wild-type (WT) littermates after renal ischemia. Renal EGFR phosphorylation was induced within 2 days after ischemia, increased over time, and remained elevated at 28 days in WT mice, but this was diminished in Wa-2 mice. At the early stage of postischemia (2 days), Wa-2 mice developed more severe acute renal tubular damage with less reparative responses as indicated by enhanced tubular cell apoptosis, and reduced dedifferentiation and proliferation as compared to WT animals. At the late stage of postischemia (28 days), Wa-2 mice exhibited a less severe renal interstitial fibrosis as shown by reduced activation/proliferation of renal myofibroblasts and decreased deposition of extracellular matrix proteins. EGFR activation also contributed to cell cycle arrest at the G2/M phase, a cellular event associated with production of profibrogenetic factors, in the injured kidney. Collectively, these results indicate that severe AKI results in sustained activation of EGFR, which is required for reparative response of renal tubular cells initially, but eventually leads to fibrogenesis.

Blocking the class I histone deacetylase ameliorates renal fibrosis and inhibits renal fibroblast activation via modulating TGF-beta and EGFR signaling

BACKGROUND

Histone deacetylase (HDAC) inhibitors are promising anti-fibrosis drugs; however, nonselective inhibition of class I and class II HDACs does not allow a detailed elucidation of the individual HDAC functions in renal fibrosis. In this study, we investigated the effect of MS-275, a selective class I HDAC inhibitor, on the development of renal fibrosis in a murine model of unilateral ureteral obstruction (UUO) and activation of cultured renal interstitial fibroblasts.

METHODS/FINDINGS

The UUO model was established by ligation of the left ureter and the contralateral kidney was used as a control. At seven days after UUO injury, kidney developed fibrosis as indicated by deposition of collagen fibrils and increased expression of collagen I, fibronectin and alpha-smooth muscle actin (alpha-SMA). Administration of MS-275 inhibited all these fibrotic responses and suppressed UUO-induced production of transforming growth factor-beta1 (TGF-beta), increased expression of TGF-beta receptor I, and phosphorylation of Smad-3. MS-275 was also effective in suppressing phosphorylation and expression of epidermal growth factor receptor (EGFR) and its downstream signaling molecule, signal transducer and activator of transcription-3. Moreover, class I HDAC inhibition reduced the number of renal tubular cells arrested in the G2/M phase of the cell cycle, a cellular event associated with TGF-beta1overproduction. In cultured renal interstitial fibroblasts, MS-275 treatment inhibited TGF-beta induced phosphorylation of Smad-3, differentiation of renal fibroblasts to myofibroblasts and proliferation of myofibroblasts.

CONCLUSIONS AND SIGNIFICANCE

These results demonstrate that class I HDACs are critically involved in renal fibrogenesis and renal fibroblast activation through modulating TGF-beta and EGFR signaling and suggest that blockade of class I HDAC may be a useful treatment for renal fibrosis.