Hickson, LaTonya J.

AbstractCell stress may give rise to insuperable growth arrest, which is defined as cellular senescence. Stenotic kidney (STK) ischemia and injury induced by renal artery stenosis (RAS) may be associated with cellular senescence. Mesenchymal stem cells (MSCs) decrease some forms of STK injury, but their ability to reverse senescence in RAS remains unknown. We hypothesized that RAS evokes STK senescence, which would be ameliorated by MSCs. Mice were studied after 4 weeks of RAS, RAS treated with adipose tissue‐derived MSCs 2 weeks earlier, or sham. STK senescence‐associated β‐galactosidase (SA‐β‐Gal) activity was measured. Protein and gene expression was used to assess senescence and the senescence‐associated secretory phenotype (SASP), and staining for renal fibrosis, inflammation, and capillary density. In addition, senescence was assessed as p16+ and p21+ urinary exosomes in patients with renovascular hypertension (RVH) without or 3 months after autologous adipose tissue‐derived MSC delivery, and in healthy volunteers (HV). In RAS mice, STK SA‐β‐Gal activity increased, and senescence and SASP marker expression was markedly elevated. MSCs improved renal function, fibrosis, inflammation, and capillary density, and attenuated SA‐β‐Gal activity, but most senescence and SASP levels remained unchanged. Congruently, in human RVH, p21+ urinary exosomes were elevated compared to HV, and only slightly improved by MSC, whereas p16+ exosomes remained unchanged. Therefore, RAS triggers renal senescence in both mice and human subjects. MSCs decrease renal injury, but only partly mitigate renal senescence. These observations support exploration of targeted senolytic therapy in RAS.

AbstractBackgroundFrailty and decreased functional status are risk factors for adverse kidney transplant (KT) outcomes. Our objective was to examine the efficacy of an exercise intervention on frailty and decreased functional status in a cohort of patients with advanced chronic kidney disease (CKD).MethodsWe conducted a prospective study involving 21 adults with ≥stage 4 CKD who were (a) frail or pre‐frail by Fried phenotype and/or (b) had lower extremity impairment [short physical performance battery score ≤10]. The intervention consisted of two supervised outpatient exercise sessions per week for 8 weeks.ResultsAmong our cohort, median participant age was 62 years (interquartile range, 53‐67) and 85.7% had been evaluated for KT. Following the study, participants reported satisfaction with the intervention and multiple frailty parameters improved significantly, including fatigue, physical activity, walking time, and grip strength. Lower extremity impairment also improved (90.5%‐61.9%, P = .03). No study‐related adverse events occurred.ConclusionsPreliminary data from this study suggest that a supervised, outpatient exercise intervention is safe, acceptable, feasible, and associated with improved frailty parameters, and lower extremity function, in patients with advanced CKD. Further studies are needed to confirm these findings and determine whether this prehabilitation strategy improves KT outcomes.

Cellular senescence, a permanent arrest of cell proliferation, is characterized by a senescence-associated secretory phenotype (SASP), which reinforces senescence and exerts noxious effects on adjacent cells. Recent studies have suggested that transplanting small numbers of senescent cells suffices to provoke tissue inflammation. We hypothesized that senescent cells can directly augment renal injury. Primary scattered tubular-like cells (STCs) acquired from pig kidneys were irradiated by 10 Gy of cesium radiation, and 3 wk later cells were characterized for levels of senescence and SASP markers. Control or senescent STCs were then prelabeled and injected (5 × 105 cells) into the aorta of C57BL/6J mice. Four weeks later, renal oxygenation was studied in vivo using 16.4-T magnetic resonance imaging and function by plasma creatinine level. Renal markers of SASP, fibrosis, and microvascular density were evaluated ex vivo. Per flow cytometry, irradiation induced senescence in 80–99% of STCs, which showed increased gene expression of senescence and SASP markers, senescence-associated β-galactosidase staining, and cytokine levels (especially IL-6) secreted in conditioned medium. Four weeks after injection, cells were detected engrafted in the mouse kidneys with no evidence for rejection. Plasma creatinine and renal tissue hypoxia increased in senescent compared with control cells. Senescent kidneys were more fibrotic, with fewer CD31+ endothelial cells, and showed upregulation of IL-6 gene expression. Therefore, exogenously delivered senescent renal STCs directly injure healthy mouse kidneys. Additional studies are needed to determine the role of endogenous cellular senescence in the pathogenesis of kidney injury and evaluate the utility of senolytic therapy.

Objective Activin A, an inflammatory mediator implicated in cellular senescence-induced adipose tissue dysfunction and profibrotic kidney injury, may become a new target for the treatment of diabetic kidney disease (DKD) and chronic kidney diseases. We tested the hypothesis that human DKD-related injury leads to upregulation of activin A in blood and urine and in a human kidney cell model. We further hypothesized that circulating activin A parallels kidney injury markers in DKD. Research design and methods In two adult diabetes cohorts and controls (Minnesota, USA; Galway, Ireland), the relationships between plasma (or urine) activin A, estimated glomerular filtration rate (eGFR) and DKD injury biomarkers were tested with logistic regression and correlation coefficients. Activin A, inflammatory, epithelial-mesenchymal-transition (EMT) and senescence markers were assayed in human kidney (HK-2) cells incubated in high glucose plus transforming growth factor-β1 or albumin. Results Plasma activin A levels were elevated in diabetes (n=206) compared with controls (n=76; 418.1 vs 259.3 pg/mL; p<0.001) and correlated inversely with eGFR (r s =−0.61; p<0.001; diabetes). After eGFR adjustment, only albuminuria (OR 1.56, 95% CI 1.16 to 2.09) and tumor necrosis factor receptor-1 (OR 6.40, 95% CI 1.08 to 38.00) associated with the highest activin tertile. Albuminuria also related to urinary activin (r s =0.65; p<0.001). Following in vitro HK-2 injury, activin, inflammatory, EMT genes and supernatant activin levels were increased. Conclusions Circulating activin A is increased in human DKD and correlates with reduced kidney function and kidney injury markers. DKD-injured human renal tubule cells develop a profibrotic and inflammatory phenotype with activin A upregulation. These findings underscore the role of inflammation and provide a basis for further exploration of activin A as a diagnostic marker and therapeutic target in DKD.

Background and objectives Dialysis is a preference-sensitive decision where prognosis may play an important role. Although patients desire risk prediction, nephrologists are wary of sharing this information. We reviewed the performance of prognostic indices for patients starting dialysis to facilitate bedside translation. Design, setting, participants, & measurements Systematic review and meta-analysis following the PRISMA guidelines. We searched Ovid MEDLINE, Ovid Embase, Ovid Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus for eligible studies of patients starting dialysis published from inception to December 31, 2018. Selection Criteria: Articles describing validated prognostic indices predicting mortality at the start of dialysis. We excluded studies limited to prevalent dialysis patients, AKI and studies excluding mortality in the first 1–3 months. Two reviewers independently screened abstracts, performed full text assessment of inclusion criteria and extracted: study design, setting, population demographics, index performance and risk of bias. Pre-planned random effects meta-analysis was performed stratified by index and predictive window to reduce heterogeneity. Results Of 12,132 articles screened and 214 reviewed in full text, 36 studies were included describing 32 prognostic indices. Predictive windows ranged from 3 months to 10 years, cohort sizes from 46 to 52,796. Meta-analysis showed discrimination area under the curve (AUC) of 0.71 (95% confidence interval, 0.69 to 073) with high heterogeneity ( I 2 =99.12). Meta-analysis by index showed highest AUC for The Obi, Ivory, and Charlson comorbidity index (CCI)=0.74, also CCI was the most commonly used (ten studies). Other commonly used indices were Kahn-Wright index (eight studies, AUC 0.68), Hemmelgarn modification of the CCI (six studies, AUC 0.66) and REIN index (five studies, AUC 0.69). Of the indices, ten have been validated externally, 16 internally and nine were pre-existing validated indices. Limitations include heterogeneity and exclusion of large cohort studies in prevalent patients. Conclusions Several well validated indices with good discrimination are available for predicting survival at dialysis start.

Mesenchymal stromal/stem cells (MSCs) belong to the endogenous cellular reparative system, and can be used exogenously in cell-based therapy. MSCs release extracellular vesicles (EVs), including exosomes and microvesicles, which mediate some of their therapeutic activity through intercellular communication. We have previously demonstrated that metabolic syndrome (MetS) modifies the cargo packed within swine EV, but whether it influences their phenotypical characteristics remains unclear. This study tested the hypothesis that MetS shifts the size distribution of MSC-derived EVs. Adipose tissue-derived MSC-EV subpopulations from Lean ( n = 6) and MetS ( n = 6) pigs were characterized for number and size using nanoparticle-tracking analysis, flow cytometry, and transmission electron microscopy. Expression of exosomal genes was determined using next-generation RNA-sequencing (RNA-seq). The number of EV released from Lean and MetS pig MSCs was similar, yet MetS-MSCs yielded a higher proportion of small-size EVs (202.4 ± 17.7 nm vs. 280.3 ± 15.1 nm), consistent with exosomes. RNA-seq showed that their EVs were enriched with exosomal markers. Lysosomal activity remained unaltered in MetS-MSCs. Therefore, MetS alters the size distribution of MSC-derived EVs in favor of exosome release. These observations may reflect MSC injury and membrane recycling in MetS or increased expulsion of waste products, and may have important implications for development of adequate cell-based treatments.

Abstract Adipose tissue inflammation and dysfunction are associated with obesity‐related insulin resistance and diabetes, but mechanisms underlying this relationship are unclear. Although senescent cells accumulate in adipose tissue of obese humans and rodents, a direct pathogenic role for these cells in the development of diabetes remains to be demonstrated. Here, we show that reducing senescent cell burden in obese mice, either by activating drug‐inducible “suicide” genes driven by the p16 Ink4a promoter or by treatment with senolytic agents, alleviates metabolic and adipose tissue dysfunction. These senolytic interventions improved glucose tolerance, enhanced insulin sensitivity, lowered circulating inflammatory mediators, and promoted adipogenesis in obese mice. Elimination of senescent cells also prevented the migration of transplanted monocytes into intra‐abdominal adipose tissue and reduced the number of macrophages in this tissue. In addition, microalbuminuria, renal podocyte function, and cardiac diastolic function improved with senolytic therapy. Our results implicate cellular senescence as a causal factor in obesity‐related inflammation and metabolic derangements and show that emerging senolytic agents hold promise for treating obesity‐related metabolic dysfunction and its complications.

BACKGROUNDAlthough posthospitalization care transitions programs (CTP) are highly diverse, their overall program thoroughness is most predictive of their success.OBJECTIVETo identify components of a successful homebased CTP and patient characteristics that are most predictive of reduced 30‐day readmissions.DESIGNRetrospective cohort.PATIENTSA total of 315 community‐dwelling, hospitalized, older adults (≥60 years) at high risk for readmission (Elder Risk Assessment score ≥16), discharged home over the period of January 1, 2011 to June 30, 2013.SETTINGMidwest primary care practice in an integrated health system.INTERVENTIONEnrollment in a CTP during acute hospitalization.MEASUREMENTSThe primary outcome was all‐cause readmission within 30 days of the first CTP evaluation. Logistic regression was used to examine independent variables, including patient demographics, comorbidities, number of medications, completion, and timing of program fidelity measures, and prior utilization of healthcare.RESULTSThe overall 30‐day readmission rate was 17.1%. The intensity of follow‐up varied among patients, with 17.1% and 50.8% of the patients requiring one and ≥3 home visits, respectively, within 30 days. More than half (54.6%) required visits beyond 30 days. Compared with patients who were not readmitted, readmitted patients were less likely to exhibit cognitive impairment (29.6% vs 46.0%; P = .03) and were more likely to have high medication use (59.3% vs 44.4%; P = .047), more emergency department (ED; 0.8 vs 0.4; P = .03) and primary care visits (4.0 vs 3.0; P = .018), and longer cumulative time in the hospital (4.6 vs 2.5 days; P = .03) within 180 days of the index hospitalization. Multivariable analysis indicated that only cognitive impairment and previous ED visits were important predictors of readmission.CONCLUSIONSNo single CTP component reliably predicted reduced readmission risk. Patients with cognitive impairment and polypharmacy derived the most benefit from the program.

Mesenchymal stem cells (MSCs) constitute an important repair system, but may be impaired by exposure to cardiovascular risk factors. Consequently, adipose tissue-derived MSCs from pigs with the metabolic syndrome (MetS) show decreased vitality. A growing number of microRNAs (miRNAs) are recognized as key modulators of senescence, but their role in regulating senescence in MSC in MetS is unclear. We tested the hypothesis that MetS upregulates in MSC expression of miRNAs that can serve as post-transcriptional regulators of senescence-associated (SA) genes. MSCs were collected from swine abdominal adipose tissue after 16 weeks of Lean or Obese diet ( n = 6 each). Next-generation miRNA sequencing (miRNA-seq) was performed to identify miRNAs up-or down-regulated in MetS-MSCs compared with Lean-MSCs. Functional pathways of SA genes targeted by miRNAs were analyzed using gene ontology. MSC senescence was evaluated by p16 and p21 immunoreactivity, H2AX protein expression, and SA-β-Galactosidase activity. In addition, gene expression of p16, p21, MAPK3 (ERK1) and MAPK14, and MSC migration were studied after inhibition of SA-miR-27b. Senescence biomarkers were significantly elevated in MetS-MSCs. We found seven upregulated miRNAs, including miR-27b, and three downregulated miRNAs in MetS-MSCs, which regulate 35 SA genes, particularly MAPK signaling. Inhibition of miR-27b in cultured MSCs downregulated p16 and MARP3 genes, and increased MSC migration. MetS modulates MSC expression of SA-miRNAs that may regulate their senescence, and the p16 pathway seems to play an important role in MetS-induced MSC senescence.

Background and objectives Withdrawal from maintenance hemodialysis before death has become more common because of high disease and treatment burden. The study objective was to identify patient factors and examine the terminal course associated with hemodialysis withdrawal, and assess patterns of palliative care involvement before death among patients on maintenance hemodialysis. Design, setting, participants, & measurements We designed an observational cohort study of adult patients on incident hemodialysis in a midwestern United States tertiary center, from January 2001 to November 2013, with death events through to November 2015. Logistic regression models evaluated associations between patient characteristics and withdrawal status and palliative care service utilization. Results Among 1226 patients, 536 died and 262 (49% of 536) withdrew. A random sample (10%; 52 out of 536) review of Death Notification Forms revealed 73% sensitivity for withdrawal. Risk factors for withdrawal before death included older age, white race, palliative care consultation within 6 months, hospitalization within 30 days, cerebrovascular disease, and no coronary artery disease. Most withdrawal decisions were made by patients (60%) or a family member (33%; surrogates). The majority withdrew either because of acute medical complications (51%) or failure to thrive/frailty (22%). After withdrawal, median time to death was 7 days (interquartile range, 4–11). In-hospital deaths were less common in the withdrawal group (34% versus 46% nonwithdrawal, P =0.003). A third (34%; 90 out of 262) of those that withdrew received palliative care services. Palliative care consultation in the withdrawal group was associated with longer hemodialysis duration (odds ratio, 1.19 per year; 95% confidence interval, 1.10 to 1.3; P <0.001), hospitalization within 30 days of death (odds ratio, 5.78; 95% confidence interval, 2.62 to 12.73; P <0.001), and death in hospital (odds ratio, 1.92; 95% confidence interval, 1.13 to 3.27; P =0.02). Conclusions In this single-center study, the rate of hemodialysis withdrawals were twice the frequency previously described. Acute medical complications and frailty appeared to be driving factors. However, palliative care services were used in only a minority of patients.