Acute kidney disease: an overview of the epidemiology, pathophysiology, and management

Metabolic Syndrome Components and Its Impact on Acute Kidney Injury After Total Joint Arthroplasty

BACKGROUND

Metabolic syndrome (MetS) is an independent risk factor for postoperative complications. This study aimed to evaluate the associated risk of MetS for perioperative complications, especially urinary complications, in patients who underwent primary total knee arthroplasty (TKA) or total hip arthroplasty (THA).

METHODS

We used a publicly available all-payer administrative database to identify patients undergoing TKA and THA from 2016 to 2020. The primary exposure of interest was MetS. Multivariable adjusted models based on propensity score matching were used to evaluate the association of MetS components with acute kidney injury (AKI), urinary tract infection (UTI), and acute posthemorrhagic anemia (APHA) in patients who underwent TKA and THA. A counterfactual-based mediation analysis was conducted to investigate the mediating effect of APHA on the relationship between MetS and AKI.

RESULTS

The analysis included 2,097,940 (16.4% with MetS) THA and 3,073,310 (24.0% with MetS) TKA adult hospitalizations. Multivariable adjustment analysis indicated MetS was associated with an increased risk of AKI (odds ratio [OR] 1.78, 95% confidence interval [CI] 1.69 to 1.89 for THA; OR 1.88, 95% CI 1.79 to 1.96 for TKA), UTI (OR 1.13, 95% CI 1.03 to 1.23 for THA; OR 1.26, 95% CI 1.17 to 1.35 for TKA), and APHA (OR 1.17, 95% CI 1.14 to 1.20 for THA; OR 1.7, 95% CI 1.15 to 1.19 for TKA). The risk of AKI increased with the number of MetS components, with ORs ranging from 2.58 to 9.46 in TKA patients and from 2.22 to 5.75 in THA patients. This increase was particularly associated with diabetes and hypertension, which were the most significant associated risk factors. Furthermore, APHA mediated the association between MetS and AKI.

CONCLUSIONS

The prevalence of MetS is increasing in TKA and THA patients. Metabolic syndrome was associated with increased risk of AKI, UTI, and APHA. The risk of AKI increased with each additional MetS component, with diabetes and hypertension contributing most. In addition, APHA may play a partial mediating role in MetS-induced AKI.

Lymphocytes and innate immune cells in acute kidney injury and repair

Acute kidney injury (AKI) is a common and serious disease entity that affects native kidneys and allografts but for which no specific treatments exist. Complex intrarenal inflammatory processes driven by lymphocytes and innate immune cells have key roles in the development and progression of AKI. Many studies have focused on prevention of early injury in AKI. However, most patients with AKI present after injury is already established. Increasing research is therefore focusing on mechanisms of renal repair following AKI and prevention of progression from AKI to chronic kidney disease. CD4+ and CD8+ T cells, B cells and neutrophils are probably involved in the development and progression of AKI, whereas regulatory T cells, double-negative T cells and type 2 innate lymphoid cells have protective roles. Several immune cells, such as macrophages and natural killer T cells, can have both deleterious and protective effects, depending on their subtype and/or the stage of AKI. The immune system not only participates in injury and repair processes during AKI but also has a role in mediating AKI-induced distant organ dysfunction. Targeted manipulation of immune cells is a promising therapeutic strategy to improve AKI outcomes.

Acknowledging acute kidney disease following ureteroscopy and laser lithotripsy: results from a tertiary care referral center

BACKGROUND

Acute kidney disease (AKD) is a recently described syndrome consisting of kidney function abnormalities lasting less than 3 months. Little is known regarding AKD following ureteroscopy (URS) and laser lithotripsy.

OBJECTIVE

To evaluate the occurrence and evolution of AKD in stone patients treated with URS.

MATERIALS AND METHODS

Data from 284 patients treated with URS for urinary stones were retrospectively analyzed. According to the KDIGO 2020 criteria, AKD was defined as postoperative acute kidney injury (AKI) occurrence, estimated glomerular filtration rate (eGFR) decrease ≥ 35%, or serum creatinine (SCr) increase ≥ 50%. AKI was defined as SCr increase ≥ 0.3 mg/dL or ≥ 50%. AKD evolution was evaluated 60 days post-URS. Data were analyzed using descriptive statistics. Univariable (UVA) and multivariable (MVA) logistic regression analyses tested the association of patients' characteristics and perioperative data with the occurrence of AKD.

RESULTS

Overall, postoperative AKD occurred in 32 (11.3%) patients. Recovery from AKD was found in 26 (82%) patients and persistent AKD occurred in 6 (18%) patients. At UVA, age at surgery (p = 0.05), baseline SCr (p = 0.02), baseline CKD category (p = 0.006), Charlson comorbidity index (p = 0.01), operative time (p = 0.04) and postoperative complications (< 0.001) were associated with AKD. At MVA, CKD category (OR 2.99, 95% CI = 1.4-6.3; p = 0.004), operative time (OR 1.01, 95% CI = 1.001-1.018; p = 0.023) and postoperative complications (OR 3.5, 95% CI = 1.46-8.49; p = 0.005) were independent predictors of AKD.

CONCLUSIONS

AKD is a frequent complication in patients treated with URS. Moreover, AKD persists in a non-neglectable percentage of patients at medium-term follow-up. Therefore, nephrological assessment should be considered, especially in high-risk patients. Current findings should be considered for the peri-operative management of stone patients.

Management of acute kidney disease in type 2 diabetes: the potential role of GLP-1 RAs and SGLT2-Is

Acute kidney disease (AKD) is defined as subacute damage and/or loss of kidney function occurring 7 to 90 days after acute kidney injury (AKI), and bearing a high risk of progression to chronic kidney disease. Current management of AKD is non-specific and includes prevention of repeated AKI, early and regular follow-up by a nephrologist, resumption and dose adjustment of statins and renin-angiotensin system inhibitors, optimization of blood pressure control, nutrition management, and nephrotoxin avoidance. Recently, SGLT2i and GLP1- RAs have emerged as potential therapeutic tools preventing the transition from acute to chronic kidney disease due to their efficacy in preserving renal function.

Machine learning approaches toward an understanding of acute kidney injury: current trends and future directions

Acute kidney injury (AKI) is a significant health challenge associated with adverse patient outcomes and substantial economic burdens. Many authors have sought to prevent and predict AKI. Here, we comprehensively review recent advances in the use of artificial intelligence (AI) to predict AKI, and the associated challenges. Although AI may detect AKI early and predict prognosis, integration of AI-based systems into clinical practice remains challenging. It is difficult to identify AKI patients using retrospective data; information preprocessing and the limitations of existing models pose problems. It is essential to embrace standardized labeling criteria and to form international multi-institutional collaborations that foster high-quality data collection. Additionally, existing constraints on the deployment of evolving AI technologies in real-world healthcare settings and enhancement of the reliabilities of AI outputs are crucial. Such efforts will improve the clinical applicability, performance, and reliability of AKI Clinical Support Systems, ultimately enhancing patient prognoses.

Impact of Renin-Angiotensin System Blockade on Mortality and Allograft Loss among Renal Transplant Recipients: A Systematic Review and Meta-Analysis

INTRODUCTION

The blockade of the renin-angiotensin system (RAS) has a beneficial effect on reducing the levels of proteinuria and blood pressure in patients with chronic kidney disease (CKD) and reduces the risk of developing end-stage kidney disease in CKD patients. Nonetheless, a debate persists regarding the impact of RAS inhibitors on outcomes such as mortality and graft survival in renal transplant patients. To assess the effect of RAS inhibitors on graft recipients in the past decade, we conducted a systematic review and meta-analysis.

METHODS

We searched Embase, PubMed, and the Cochrane Central Register of Clinical Trials from January 1, 2012, to August 1, 2022. We included 14 articles, comprising 5 randomized controlled trials (RCTs) and 9 cohort studies, including 45,377 patients. These studies compared patient or graft survival between an RAS inhibitor treatment arm and a control arm.

RESULTS

The meta-analysis revealed that RAS blockade was significantly associated with lower mortality in cohort studies (risk ratio [RR] = 0.66, 95% confidence interval [CI]: 0.55-0.79), reduced allograft loss in cohort studies (RR = 0.62, 95% CI: 0.54-0.71), and significant changes in systolic blood pressure in RCTs. Subgroup analysis of the groups of interest (interventions involving RAS blockade, follow-up period of ≥5 years) showed consistently reduced mortality (RR = 0.67, 95% CI: 0.56-0.81) and reduced allograft loss (RR = 0.61, 95% CI: 0.54-0.70).

CONCLUSIONS

Our results demonstrated that the application of RAS blockade among renal transplant recipients was associated with lower mortality and allograft loss in cohort studies but not in RCTs. More powered clinical trials are needed to evaluate the effects of RAS blockade in renal transplant recipients.

Time-restricted feeding protects against cisplatin-induced acute kidney injury in mice

BACKGROUND

Time-restricted feeding (TRF), devoid of calorie restriction, is acknowledged for promoting metabolic health and mitigating various chronic metabolic diseases. While TRF exhibits widespread benefits across multiple tissues, there is limited exploration into its impact on kidney function. In this study, our aim was to investigate the potential ameliorative effects of TRF on kidney damage in a mouse model of cisplatin-induced acute kidney injury (AKI).

METHODS

Cisplatin-induced AKI was induced through intraperitoneal injection of cisplatin into C57BL/6 male mice. Mice undergoing TRF were provided unrestricted access to standard chow daily but were confined to an 8-hour feeding window during the dark cycle for 2 weeks before cisplatin injection. The mice were categorized into four groups: control, TRF, cisplatin, and TRF + cisplatin.

RESULTS

The tubular damage score and serum creatinine levels were significantly lower in the TRF + cisplatin group compared to the cisplatin group. The TRF + cisplatin group exhibited reduced expression of phosphorylated nuclear factor kappa B, inflammatory cytokines, and F4/80-positive macrophages compared to the cisplatin group. Furthermore, oxidative stress markers for DNA, protein, and lipid were markedly decreased in the TRF + cisplatin group compared to the cisplatin group. TUNEL-positive tubular cells, cleaved caspase-3 expression, and the Bax/Bcl-2 ratio in the TRF + cisplatin group were lower than those in the cisplatin group.

CONCLUSION

TRF, without calorie restriction, effectively mitigated kidney damage by suppressing inflammatory reactions, oxidative stress, and tubular apoptosis in a mouse model of cisplatin-induced AKI. TRF holds promise as a novel dietary intervention for preventing cisplatin-induced AKI.

Double-negative T cells have a reparative role after experimental severe ischemic acute kidney injury

T cells mediate organ injury and repair. A proportion of unconventional kidney T cells called double-negative (DN) T cells (TCR+ CD4- CD8-), with anti-inflammatory properties, were previously demonstrated to protect from early injury in moderate experimental acute kidney injury (AKI). However, their role in repair after AKI has not been studied. We hypothesized that DN T cells mediate repair after severe AKI. C57B6 mice underwent severe (40 min) unilateral ischemia-reperfusion injury (IRI). Kidney DN T cells were studied by flow cytometry and compared with gold-standard anti-inflammatory CD4+ regulatory T cells (Tregs). In vitro effects of DN T cells and Tregs on renal tubular epithelial cell (RTEC) repair after injury were quantified with live-cell analysis. DN T cells, Tregs, CD4, or vehicle were adoptively transferred after severe AKI. Glomerular filtration rate (GFR) was measured using fluorescein isothiocyanate (FITC)-sinistrin. Fibrosis was assessed with Masson's trichrome staining. Profibrotic genes were measured with qRT-PCR. Percentages and the numbers of DN T cells substantially decreased during repair phase after severe AKI, as well as their activation and proliferation. Both DN T cells and Tregs accelerated RTEC cell repair in vitro. Post-AKI transfer of DN T cells reduced kidney fibrosis and improved GFR, as did Treg transfer. DN T cell transfer lowered transforming growth factor (TGF)β1 and α-smooth muscle actin (αSMA) expression. DN T cells reduced effector-memory CD4+ T cells and IL-17 expression. DN T cells undergo quantitative and phenotypical changes after severe AKI, accelerate RTEC repair in vitro as well as improve GFR and renal fibrosis in vivo. DN T cells have potential as immunotherapy to accelerate repair after AKI.NEW & NOTEWORTHY Double-negative (DN) T cells (CD4- CD8-) are unconventional kidney T cells with regulatory abilities. Their role in repair from acute kidney injury (AKI) is unknown. Kidney DN T cell population decreased during repair after ischemic AKI, in contrast to regulatory T cells (Tregs) which increased. DN T cell administration accelerated tubular repair in vitro, while after severe in vivo ischemic injury reduced kidney fibrosis and increased glomerular filtration rate (GFR). DN T cell infusion is a potential therapeutic agent to improve outcome from severe AKI.

Pre-treatment with β-hydroxybutyrate mitigates cisplatin-induced acute kidney injury

β-Hydroxybutyrate (β-HB), the primary circulating ketone body, plays a dual role as both a metabolic fuel and an endogenous signaling molecule, offering diverse systemic benefits. Recent studies have highlighted the renoprotective effects of exogenous β-HB therapy in various animal models of kidney disease. In this investigation, our goal was to assess whether pre-treatment with exogenous β-HB could alleviate kidney damage in a mouse model of cisplatin-induced acute kidney injury (AKI). Prior to cisplatin administration, intraperitoneal administration of β-HB was carried out, and the groups were classified into four: Sham, β-HB, cisplatin, and β-HB + cisplatin. The tubular damage score and serum creatinine levels were significantly lower in the β-HB + cisplatin group compared to the cisplatin group. Furthermore, the expression of phosphorylated NF-κB, inflammatory cytokines, and the quantity of F4/80-positive macrophages in the β-HB + cisplatin group were reduced compared to those in the cisplatin group. Additionally, oxidative stress markers for DNA, protein, and lipid in the β-HB + cisplatin group were markedly diminished compared to those in the cisplatin group. The number of TUNEL-positive and cleaved caspase 3-positive tubular cells in the β-HB + cisplatin group was lower than in the cisplatin group. Pre-treating with exogenous β-HB effectively mitigated kidney damage by suppressing inflammation, oxidative stress, and tubular apoptosis in cisplatin-induced AKI. Therefore, exogenous β-HB as a pre-treatment emerges as a promising and novel strategy for preventing cisplatin-induced AKI.

Exosome-Based Drug Delivery: Translation from Bench to Clinic

Exosome-based drug delivery is emerging as a promising field with the potential to revolutionize therapeutic interventions. Exosomes, which are small extracellular vesicles released by various cell types, have attracted significant attention due to their unique properties and natural ability to transport bioactive molecules. These nano-sized vesicles, ranging in size from 30 to 150 nm, can effectively transport a variety of cargoes, including proteins, nucleic acids, and lipids. Compared to traditional drug delivery systems, exosomes exhibit unique biocompatibility, low immunogenicity, and reduced toxicity. In addition, exosomes can be designed and tailored to improve targeting efficiency, cargo loading capacity, and stability, paving the way for personalized medicine and precision therapy. However, despite the promising potential of exosome-based drug delivery, its clinical application remains challenging due to limitations in exosome isolation and purification, low loading efficiency of therapeutic cargoes, insufficient targeted delivery, and rapid elimination in circulation. This comprehensive review focuses on the transition of exosome-based drug delivery from the bench to clinic, highlighting key aspects, such as exosome structure and biogenesis, cargo loading methods, surface engineering techniques, and clinical applications. It also discusses challenges and prospects in this emerging field.