Genome homeostasis defects drive enlarged cells into senescence.

Cellular senescence refers to an irreversible state of cell-cycle arrest and plays important roles in aging and cancer biology. Because senescence is associated with increased cell size, we used reversible cell-cycle arrests combined with growth rate modulation to study how excessive growth affects proliferation. We find that enlarged cells upregulate p21, which limits cell-cycle progression. Cells that re-enter the cell cycle encounter replication stress that is well tolerated in physiologically sized cells but causes severe DNA damage in enlarged cells, ultimately resulting in mitotic failure and permanent cell-cycle withdrawal. We demonstrate that enlarged cells fail to recruit 53BP1 and other non-homologous end joining (NHEJ) machinery to DNA damage sites and fail to robustly initiate DNA damage-dependent p53 signaling, rendering them highly sensitive to genotoxic stress. We propose that an impaired DNA damage response primes enlarged cells for persistent replication-acquired damage, ultimately leading to cell division failure and permanent cell-cycle exit.

Too big not to fail: emerging evidence for size-induced senescence.

Cellular senescence refers to a permanent and stable state of cell cycle exit. This process plays an important role in many cellular functions, including tumor suppression. It was first noted that senescence is associated with increased cell size in the early 1960s; however, how this contributes to permanent cell cycle exit was poorly understood until recently. In this review, we discuss new findings that identify increased cell size as not only a consequence but also a cause of permanent cell cycle exit. We highlight recent insights into how increased cell size alters normal cellular physiology and creates homeostatic imbalances that contribute to senescence induction. Finally, we focus on the potential clinical implications of these findings in the context of cell cycle arrest-causing cancer therapeutics and speculate on how tumor cell size changes may impact outcomes in patients treated with these drugs.

Telehealth versus face-to-face visits: A comprehensive outpatient perspective-based cohort study of patients with kidney disease.

BACKGROUND: Telenephrology has become an important health care delivery modality during the COVID-19 pandemic. However, little is known about patient perspectives on the quality of care provided via telenephrology compared to face-to-face visits. We aimed to use objective data to study patients' perspectives on outpatient nephrology care received via telenephrology (phone and video) versus face-to-face visits. METHODS: We retrospectively studied adults who received care in the outpatient Nephrology & Hypertension division at Mayo Clinic, Rochester, from March to July 2020. We used a standardized survey methodology to evaluate patient satisfaction. The primary outcome was the percent of patients who responded with a score of good (4) or very good (5) on a 5-point Likert scale on survey questions that asked their perspectives on access to their nephrologist, relationship with care provider, their opinions on the telenephrology technology, and their overall assessment of the care received. Wilcoxon rank sum tests and chi-square tests were used as appropriate to compare telenephrology versus face-to-face visits. RESULTS: 3,486 of the patient encounters were face-to-face, 808 phone and 317 video visits. 443 patients responded to satisfaction surveys, and 21% of these had telenephrology encounters. Established patients made up 79.6% of telenephrology visits and 60.9% of face-to-face visits. There was no significant difference in patient perceived access to health care, satisfaction with their care provider, or overall quality of care between patients cared for via telenephrology versus face-to-face. Patient satisfaction was also equally high. CONCLUSIONS: Patient satisfaction was equally high amongst those patients seen face-to-face or via telenephrology.

Rituximab-Associated Flare of Cryoglobulinemic Vasculitis.

BACKGROUND: Patients with cryoglobulinemic vasculitis (CV) can develop disease flare after rituximab administration. The objective of our study was to describe the prevalence, clinical characteristics, predisposing factors, and outcomes of patients with rituximab-associated flare of CV. METHODS: We conducted a retrospective study in a tertiary referral center until March 25, 2020. RESULTS: Among 64 patients with CV who received rituximab therapy in our center, 14 (22%) developed disease flare. Median age was 67.5 years. Seven patients (50%) had type II CV and the other half had either type I (n = 6) or type III (n = 1). Twelve patients (86%) had an underlying B-cell lymphoproliferative disorder as the cause of their CV. CV flare occurred after a median time of 5.5 days (range: 2-8 days). The organ systems most involved were the skin (n = 10), kidneys (n = 5), and peripheral nerves (n = 3). Five patients (36%) developed acute kidney injury (AKI), 3 of whom presented with nephritic syndrome secondary to biopsy-proven membranoproliferative glomerulonephritis. Treatment was directed against the underlying disease in addition to supportive care. Patients who developed flare were more likely to have B-cell lymphoproliferative disorder as the underlying etiology of their CV (P = 0.03). Eight patients (57%) died after a median time of 27 months. CONCLUSIONS: Rituximab-associated flare can occur in all types of CV, tends to arise approximately 2 days and less than 1 week after rituximab administration, and is more likely to happen in patients with an underlying B-cell lymphoproliferative disorder. It does not indicate treatment failure, and rituximab should not be abandoned altogether. AKI is a common manifestation, and mortality rate at 2 years is high.

Ultrasonographic Assessment of Extravascular Lung Water in Hospitalized Patients Requiring Hemodialysis: A Prospective Observational Study.

INTRODUCTION: Sonographic technologies can estimate extravascular lung water (EVLW) in hemodialysis (HD) patients. This study investigated the suitability of a handheld scanner in contrast to a portable scanner for quantifying EVLW in hospitalized patients requiring HD. METHODS: In this prospective study, 54 hospitalized HD patients were enrolled. Bedside lung ultrasound was performed within 30 min before and after dialysis using handheld (phased array transducer, 1.7-3.8 MHz) and portable (curved probe, 5-2 MHz) ultrasound devices. Eight lung zones were scanned for total B-lines number (TBLN). The maximum diameter of inferior vena cava (IVC) was measured. We performed Passing-Bablok regression, Deming regression, Bland-Altman, and logistic regression analysis. RESULTS: The 2 devices did not differ in measuring TBLN and IVC (p > 0.05), showing a high correlation (r = 0.92 and r = 0.51, respectively). Passing-Bablok regression had a slope of 1.11 and an intercept of 0 for TBLN, and the slope of Deming regression was 1.02 within the CI bands of 0.94 and 1.11 in the full cohort. TBLN was logarithmically transformed for Bland-Altman analysis, showing a bias of 0.06 (TBLN = 1.2) between devices. The slope and intercept of the Deming regression in IVC measurements were 0.77 and 0.46, respectively; Bland-Altman plot showed a bias of -0.07. Compared with predialysis, TBLN significantly (p < 0.001) decreased after dialysis, while IVC was unchanged (p = 0.16). Univariate analysis showed that cardiovascular disease (odds ratio [OR] 8.94 [2.13-61.96], p = 0.002), smoking history (OR 5.75 [1.8-20.46], p = 0.003), and right pleural effusion (OR 5.0 [1.2-25.99], p = 0.03) were strong predictors of EVLW indicated by TBLN ≥ 4. CONCLUSION: The lung and IVC findings obtained from handheld and portable ultrasound scanners are comparable and concordant. Cardiovascular disease and smoking history were strong predictors of EVLW. The use of TBLN to assess EVLW in hospitalized HD patients is feasible. Further studies are needed to determine if TBLN can help guide volume removal in HD patients.

Biomarkers, Clinical Features, and Rechallenge for Immune Checkpoint Inhibitor Renal Immune-Related Adverse Events.

INTRODUCTION: Immune checkpoint inhibitors (ICIs) are effective in treating several cancers; however, acute kidney injury (AKI) can occur as part as an immune-related adverse event (iRAE). Biomarkers at the time of AKI diagnosis may help determine whether they are ICI- related and guide therapeutic strategies. METHODS: In this retrospective study, we reviewed patients with cancer treated with ICI therapy between 2014 and 2020 who developed AKI (defined as a ≥1.5-fold increase in serum creatinine [SCr]) that was attributed to ICI (ICI-AKI) and compared them with an adjudicated non-ICI-AKI group. Clinical and laboratory features, including SCr, serum C-reactive protein (CRP), and urine retinol binding protein/urine creatinine (uRBP/Cr) levels at AKI event were evaluated. RESULTS: There were 37 patients with ICI-AKI and 13 non-ICI-AKI referents in the cohort for analysis. At time of AKI, SCr, CRP, and uRBP/Cr were significantly higher in the ICI-AKI compared with the non-ICI-AKI patients (median [interquartile range (IQR)] SCr 2.0 [1.7, 2.9] vs. 1.5 [1.3, 1.6] mg/dl, serum CRP 54.0 [33.7, 90.0] vs. 3.5 [3.0, 7.9] mg/l, and uRBP/Cr 1927 [1174, 46,522] vs. 233 [127, 989] µg/g Cr, respectively, P < 0.05 for all). Compared with the referent group, time from ICI initiation to AKI was shorter in the ICI-AKI patients. Among the ICI-AKI group, complete renal recovery occurred in 39% of patients by 3 months; rechallenge occurred in 16 (43%) of patients, of whom 3 (19%) had recurrence of AKI. CONCLUSION: Our findings suggest that serum CRP and uRBP/Cr may help to differentiate AKI due to ICI from other causes.

Immunotherapy-Related Acute Kidney Injury.

Nephrotoxicity associated with immunotherapy is increasingly being encountered in clinical practice. Drugs that augment the immune system to eradicate cancer are revolutionary in the field of oncology. Older generation immunotherapies such as high-dose interleukin and interferon-alpha are now being replaced with more effective immune checkpoint inhibitors and chimeric antigen receptor T-cell therapies, which have shown promising results in numerous clinical trials. Unfortunately, these treatments come with a unique baggage of adverse effects including nephrotoxicity. This onconephrology review summarizes the immunotherapies currently in use and their kidney-related toxicities, pathophysiology, and their management.

Hemoglobinuria in the Early Poststem-Cell-Transplant Period: Risk Factors and Association with Outcomes.

Background: Information on risk factors of hemoglobinuria after hematopoietic stem-cell transplant (HSCT) and its association with AKI, mortality, and engraftment is limited. Methods: We conducted a retrospective cohort study on all consecutive adults that underwent HSCT from January 6, 1999, to November 6, 2017. The study included 6039 patients that underwent bone marrow transplantation (BMT), umbilical cord blood, and peripheral blood stem-cell transplantation (PBSCT). Results: Early post-HSCT, AKI occurred in 393 (7%) patients, and 52 (0.9%) patients had post-HSCT hemoglobinuria. Post-HSCT hemoglobinuria was associated with graft type (BMT+Cord), underlying disease (lymphoma, acute leukemia), and fludarabine-based conditioning regimen. Post-HSCT hemoglobinuria was associated with early (48-72 hours) post-HSCT AKI. Graft type (BMT+Cord) was associated with AKI among patients with hemoglobinuria. AKI in patients with hemoglobinuria was associated with delayed platelet engraftment and delayed WBC engraftment but not 100-day mortality. Conclusion: Close monitoring is recommended in this patient group to facilitate a good engraftment outcome.

The Insulin Receptor Adaptor IRS2 is an APC/C Substrate That Promotes Cell Cycle Protein Expression and a Robust Spindle Assembly Checkpoint.

Insulin receptor substrate 2 (IRS2) is an essential adaptor that mediates signaling downstream of the insulin receptor and other receptor tyrosine kinases. Transduction through IRS2-dependent pathways is important for coordinating metabolic homeostasis, and dysregulation of IRS2 causes systemic insulin signaling defects. Despite the importance of maintaining proper IRS2 abundance, little is known about what factors mediate its protein stability. We conducted an unbiased proteomic screen to uncover novel substrates of the Anaphase Promoting Complex/Cyclosome (APC/C), a ubiquitin ligase that controls the abundance of key cell cycle regulators. We found that IRS2 levels are regulated by APC/C activity and that IRS2 is a direct APC/C target in G1 Consistent with the APC/C's role in degrading cell cycle regulators, quantitative proteomic analysis of IRS2-null cells revealed a deficiency in proteins involved in cell cycle progression. We further show that cells lacking IRS2 display a weakened spindle assembly checkpoint in cells treated with microtubule inhibitors. Together, these findings reveal a new pathway for IRS2 turnover and indicate that IRS2 is a component of the cell cycle control system in addition to acting as an essential metabolic regulator.

Systematic Review of the Safety of Immune Checkpoint Inhibitors Among Kidney Transplant Patients.

INTRODUCTION: Kidney transplant (Ktx) recipients are excluded from clinical trials of immune checkpoint inhibitors. The aim of this systematic review was to assess the safety of immune checkpoint inhibitors among Ktx patients. METHODS: A literature search was conducted using MEDLINE, EMBASE, and Cochrane Database from inception through April 2019. We included studies that reported outcomes of Ktx recipients who received immune checkpoint inhibitors for cancer treatment. Outcomes of interest were allograft rejection and/or allograft failure. RESULTS: Twenty-seven articles with a total of 44 Ktx patients treated with immune checkpoint inhibitor were identified. Of 44 Ktx patients, 18 were reported to have acute rejection. Median time from immune checkpoint inhibitors to acute rejection diagnosis was 24 (interquartile range, 10-60) days. Reported types of acute allograft rejection were cellular rejection (33%), mixed cellular and antibody-mediated rejection (17%), and unspecified type (50%). Fifteen (83%) had allograft failure and 8 (44%) died. Three patients had a partial remission (17%), 1 patient achieved cancer response (6%), and 5 patients had stable disease (28%). CONCLUSION: The findings of our study raise awareness of the increased risk for acute allograft rejection/failure following immune checkpoint inhibitors for cancer treatment among Ktx patients, in particular with programmed cell death 1 (PD-1) inhibitors. Future large-scale clinical studies are required to appraise the pathogenesis and plan optimal balanced therapy that helps sustain graft tolerance.

Clinical Features and Outcomes of Immune Checkpoint Inhibitor-Associated AKI: A Multicenter Study.

BACKGROUND: Despite increasing recognition of the importance of immune checkpoint inhibitor-associated AKI, data on this complication of immunotherapy are sparse. METHODS: We conducted a multicenter study of 138 patients with immune checkpoint inhibitor-associated AKI, defined as a ≥2-fold increase in serum creatinine or new dialysis requirement directly attributed to an immune checkpoint inhibitor. We also collected data on 276 control patients who received these drugs but did not develop AKI. RESULTS: Lower baseline eGFR, proton pump inhibitor use, and combination immune checkpoint inhibitor therapy were each independently associated with an increased risk of immune checkpoint inhibitor-associated AKI. Median (interquartile range) time from immune checkpoint inhibitor initiation to AKI was 14 (6-37) weeks. Most patients had subnephrotic proteinuria, and approximately half had pyuria. Extrarenal immune-related adverse events occurred in 43% of patients; 69% were concurrently receiving a potential tubulointerstitial nephritis-causing medication. Tubulointerstitial nephritis was the dominant lesion in 93% of the 60 patients biopsied. Most patients (86%) were treated with steroids. Complete, partial, or no kidney recovery occurred in 40%, 45%, and 15% of patients, respectively. Concomitant extrarenal immune-related adverse events were associated with worse renal prognosis, whereas concomitant tubulointerstitial nephritis-causing medications and treatment with steroids were each associated with improved renal prognosis. Failure to achieve kidney recovery after immune checkpoint inhibitor-associated AKI was independently associated with higher mortality. Immune checkpoint inhibitor rechallenge occurred in 22% of patients, of whom 23% developed recurrent associated AKI. CONCLUSIONS: This multicenter study identifies insights into the risk factors, clinical features, histopathologic findings, and renal and overall outcomes in patients with immune checkpoint inhibitor-associated AKI.

Acute Interstitial Nephritis and Checkpoint Inhibitor Therapy: Single Center Experience of Management and Drug Rechallenge.

Background: The objective of this case cohort study was to describe our experience in the care of patients with immune checkpoint inhibitor-related acute interstitial nephritis (ICI-AIN) including rechallenge. Methods: A descriptive case series of patients that received an ICI and had an AKI (defined as a ≥1.5-fold increase in serum creatinine) as an immune-related adverse event (irAE), with biopsy-proven or clinically suspected ICI-AIN from January 1, 2014 to December 1, 2018 at Mayo Clinic, Rochester. We studied details regarding diagnosis, clinical course, management, and outcomes of rechallenge of immunotherapy. Complete response (CR) was defined as return of kidney function back to baseline or <0.3 mg/dl above baseline creatinine; partial response (PR) was defined as creatinine >0.3 mg/dl from baseline, but less than twofold above the baseline by the end of steroid course. Results: A total of 14 cases of biopsy-proven (35%) or clinically suspected (65%) ICI-AIN was identified. All patients had their ICI withheld and 12 patients received steroids. Steroid regimens were highly variable. The starting equivalent dose of prednisone was higher in those that had a CR versus a PR (median 0.77 mg/kg versus 0.66 mg/kg). Proton pump inhibitors (PPIs) were used in 11 patients and were stopped in eight (73%) patients at the time of the AKI event. A CR was seen in five (63%) of the eight patients who discontinued PPIs. Rechallenge was attempted in four of the 14 patients: three were successful with no recurrence of AKI, but one patient had recurrent AKI and fatal pneumonitis. Conclusions: Careful review, withholding ICI and concomitant known AIN-inducing medications, along with prompt initial steroid management were the key in complete renal kidney recovery. A kidney biopsy should be strongly considered. Rechallenge of immunotherapy after a kidney irAE, although challenging, is possible and would need careful evaluation on an individual basis. Podcast: This article contains a podcast at https://www.asn-online.org/media/podcast/K360/2020_01_30_KID0000152019.mp3.

Polyubiquitin Chains Linked by Lysine Residue 48 (K48) Selectively Target Oxidized Proteins In Vivo.

Aims: Ubiquitin is a highly conserved protein modifier that heavily accumulates during the oxidative stress response. Here, we investigated the role of the ubiquitination system, particularly at the linkage level, in the degradation of oxidized proteins. The function of ubiquitin in the removal of oxidized proteins remains elusive because of the wide range of potential targets and different roles that polyubiquitin chains play. Therefore, we describe in detail the dynamics of the K48 ubiquitin response as the canonical signal for protein degradation. We identified ubiquitin targets and defined the relationship between protein ubiquitination and oxidation during the stress response. Results: Combining oxidized protein isolation, linkage-specific ubiquitination screens, and quantitative proteomics, we found that K48 ubiquitin accumulated at both the early and late phases of the stress response. We further showed that a fraction of oxidized proteins are conjugated with K48 ubiquitin. We identified ∼750 ubiquitinated proteins and ∼400 oxidized proteins that were modified during oxidative stress, and around half of which contain both modifications. These proteins were highly abundant and function in translation and energy metabolism. Innovation and Conclusion: Our work showed for the first time that K48 ubiquitin modifies a large fraction of oxidized proteins, demonstrating that oxidized proteins can be targeted by the ubiquitin/proteasome system. We suggest that oxidized proteins that rapidly accumulate during stress are subsequently ubiquitinated and degraded during the late phase of the response. This delay between oxidation and ubiquitination may be necessary for reprogramming protein dynamics, restoring proteostasis, and resuming cell growth.

Association between urologic malignancies and end-stage renal disease: A meta-analysis.

AIM: Previous studies have suggested a higher incidence of urologic malignancies in end-stage renal disease (ESRD) patients. However, incidence trends of urologic malignancies in ESRD patients remain unclear. The aims of the present study were: (i) to investigate the pooled incidence/incidence trends; and (ii) to assess the risk of urologic malignancies in ESRD patients. METHODS: A literature search was conducted using MEDLINE, EMBASE and Cochrane Database from inception through April 2017. Studies that reported incidence or odds ratios of urologic malignancies among ESRD patients were included. Pooled odds ratios (OR) and 95%CI were calculated using a random-effect model. The protocol for this meta-analysis is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42017067687). RESULTS: Nineteen observational studies with 1 931 073 ESRD patients were enrolled. The pooled estimated incidence of kidney cancer and urothelial cancers (carcinomas of the bladder, ureters, and renal pelvis) in ESRD patients were 0.3% (95%CI: 0.2-0.5%) and 0.5% (95%CI: 0.3-0.8%), respectively. Meta-regression showed significant positive correlation between incidence of urologic malignancies in ESRD patients and year of study (slopes = +0.05 and +0.07, P < 0.001 for kidney cancer and urothelial cancers, respectively). Compared to non-ESRD status, ESRD was significantly associated with both kidney cancer (pooled OR 6.04; 95% CI 4.70-7.77) and urothelial cancers (pooled OR 4.37; 95% CI 2.40-7.96). CONCLUSION: Our study demonstrates a significant association between ESRD and urologic malignancies. The overall estimated incidence rates of kidney cancer and urothelial cancers are 0.4% and 0.5%, respectively. There is a significant positive correlation between the incidence of urologic malignancies and year of study.

Programmed cell death protein 1 inhibitor treatment is associated with acute kidney injury and hypocalcemia: meta-analysis.

Background: The aim of this meta-analysis was to assess the risks and incidence of nephrotoxicity and electrolyte abnormalities in patients receiving programmed cell death protein 1 (PD-1) inhibitors. Methods: We conducted a meta-analysis of clinical trials that monitored electrolyte levels and kidney functions during treatment with nivolumab or pembrolizumab by searching MEDLINE, EMBASE and the Cochrane Database from inception through April 2017. Our protocol is registered with International Prospective Register of Systematic Reviews; no.CRD42017060579. Results: A total of 48 clinical trials with a total of 11 482 patients were included. The overall pooled risk ratios (RR) of all acute kidney injury (AKI) and all electrolyte abnormalities in patients treated with PD-1 inhibitors were 1.86 [95% confidence interval (CI) 0.95-3.64] and 1.67 (95% CI 0.89-3.12), respectively. Compared with non-nephrotoxic controls, the pooled RR of AKI in patients treated with PD-1 inhibitors was 4.19 (95% CI 1.57-11.18). Prespecified subgroup analyses demonstrated a significant association between PD-1 inhibitors and hypocalcemia with a pooled RR of 10.87 (95% CI 1.40-84.16). The pooled estimated incidence rates of AKI and hypocalcemia in patients treated with PD-1 inhibitors were 2.2% (95% CI 1.5-3.0%) and 1.0% (95% CI 0.6-1.8%), respectively. Among patients who developed AKI with PD-1 inhibitors, the pooled estimated rate of interstitial nephritis was 16.6% (95% CI 10.2-26.0%). Conclusions: Treatment with PD-1 inhibitors is associated with a higher risk of AKI compared with non-nephrotoxic agents. It will be important to characterize the AKI patients to better understand the etiology behind the event. In addition, treatment with PD-1 inhibitors is associated with an increased risk of hypocalcemia. This study highlights a rare but serious adverse event of anti-PD-1 antibodies and we recommend, in addition to electrolytes panel, routine calcium monitoring.

Crystalglobulin-Induced Nephropathy and Keratopathy.

Crystalglobulinemia, a rare manifestation of monoclonal gammopathy, results from vascular deposition of crystallized monoclonal proteins leading to tissue injury. A 56-year-old man initially presented several years earlier with migratory polyarthralgias and blurry vision with no unifying diagnosis. Following an acute episode of malignant hypertension and rapidly progressive kidney failure, kidney biopsy was performed and was interpreted as idiopathic thrombotic microangiopathy. Further evaluation revealed an underlying monoclonal protein disorder. Slit-lamp biomicroscopy evaluation showed crystalline keratopathy. Re-evaluation of the kidney biopsy material with pronase staining confirmed crystalglobulin-induced nephropathy. The patient was initially treated with cyclophosphamide, bortezomib, and dexamethasone with partial response, followed by autologous stem cell transplantation with normalization of monoclonal protein studies, improvement in kidney function and joint symptoms, and decreased corneal deposits. His disease recurred but did not require additional treatment 1 year later. This case exemplifies the unique systemic presentation of diseases in the monoclonal gammopathy spectrum and emphasizes the need for a multidisciplinary approach when caring for these patients.