Patients with AKI experience higher rates of heart failure (HF). This study seeks to identify criteria to assess the risk of heart failure post-hospitalization, with a special focus on AKI patients. We hypothesized that the combined use of 9 vascular biomarkers would predict future heart failure events after AKI. Using a study of 1497 hospitalized patients with and without AKI, we found that these 9 vascular biomarkers successfully stratified patients into different risk groups for HF, and were able to improve prediction of HF when added to routine clinical variables. Using the ASSESS-AKI cohort, we performed an unsupervised spectral cluster analysis with 9 plasma biomarkers measured at 3 months post-hospitalization [Angiopoietin (angpt)-1, angpt-2, vascular endothelial growth factor (VEGF)-A, VEGF-C, VEGF-d, VEGF receptor 1 (R1), solubleTie-2 (sTie-2), placental growth factor (PlGF), and basic fibroblast growth factor (bFGF)] in 1,497 patients, half of whom had AKI. We used a Cox regression analysis to evaluate the associations between the clusters and HF. Models were adjusted for demographics, cardiovascular disease risk factors, medications, ICU status, lung disease, sepsis, clinical center, and 3-month post-discharge serum creatinine and proteinuria. We calculated change in the area under the curve (AUC) for the prediction of HF or death at 3 years by adding the biomarkers to a clinical model selected by a penalized regression with LASSO. We also calculated a net reclassification index for the addition of the biomarkers to the clinical model. Three biomarker-derived clusters were identified: Cluster 1 [n = 302, Vascular Injury (Injury) Phenotype] had higher levels of injury markers, whereas Cluster 2 [n = 728, Vascular Repair (Repair) Phenotype] had higher levels of repair markers. Cluster 3 (n = 467) had lower levels of all markers (Dormant Phenotype). Across the entire cohort, those with the Injury Phenotype had twofold higher risk of a HF event compared to the Repair Phenotype [aHR 2.24 (95

Methylthioadenosine phosphorylase (MTAP) is a key enzyme in purine metabolism that may influence cellular responses to injury. We evaluated the effects of prophylactic MTAP inhibition in mouse models of ischemia-reperfusion and cisplatin-induced acute kidney injury (AKI). MTAP inhibition was confirmed by the accumulation of methylthioadenosine. Treated mice showed reduced renal injury and decreased tubular damage. Transcriptomic analysis revealed protection from inflammatory and stress pathways while maintaining oxidative phosphorylation, fatty acid metabolism, and epithelial integrity-related genes. Analysis of human single-cell RNA sequencing data from the Kidney Precision Medicine Project indicated that MTAP is highly expressed in kidney injury marker-positive adaptive proximal tubule cells, which display both reparative and maladaptive features during AKI. These findings highlight MTAP as a potential therapeutic target for modulating injury responses in AKI.NEW & NOTEWORTHY We show that prophylactic MTAP inhibition protects against experimental AKI in mice. Transcriptomic data indicate that MTAP inhibition suppresses epithelial stress and maladaptive repair-related gene programs. Single-cell analysis of human AKI biopsies supports a role for MTAP in injured proximal tubule subpopulations, identifying it as a potential therapeutic target in AKI.

Acute kidney injury (AKI) increases mortality risk and predisposes individuals to chronic kidney disease. Metabolic pathways play a crucial role in AKI pathophysiology. Here, we investigate the potential of methylthioadenosine phosphorylase (MTAP) inhibition as a novel renoprotective strategy in AKI. Using AKI mouse models, we demonstrate that a small molecule MTAP inhibitor significantly reduces kidney injury markers and improves renal histology. RNA sequencing reveals that MTAP inhibition modulates pathways associated with inflammation, oxidative phosphorylation, and cell survival. Additionally, analysis of human single-cell RNA sequencing data links MTAP expression to kidney injury marker in AKI. This study provides evidence of MTAP inhibition as a potential therapeutic strategy for AKI, highlighting metabolic dysregulation as a target for future clinical interventions.

Lactate elevation is a well-characterized biomarker of mitochondrial dysfunction, but its role in diabetic kidney disease (DKD) is not well defined. Urine lactate was measured in patients with type 2 diabetes (T2D) in 3 cohorts (HUNT3, SMART2D, CRIC). Urine and plasma lactate were measured during euglycemic and hyperglycemic clamps in participants with type 1 diabetes (T1D). Patients in the HUNT3 cohort with DKD had elevated urine lactate levels compared with age- and sex-matched controls. In patients in the SMART2D and CRIC cohorts, the third tertile of urine lactate/creatinine was associated with more rapid estimated glomerular filtration rate decline, relative to first tertile. Patients with T1D demonstrated a strong association between glucose and lactate in both plasma and urine. Glucose-stimulated lactate likely derives in part from proximal tubular cells, since lactate production was attenuated with sodium-glucose cotransporter-2 (SGLT2) inhibition in kidney sections and in SGLT2-deficient mice. Several glycolytic genes were elevated in human diabetic proximal tubules. Lactate levels above 2.5 mM potently inhibited mitochondrial oxidative phosphorylation in human proximal tubule (HK2) cells. We conclude that increased lactate production under diabetic conditions can contribute to mitochondrial dysfunction and become a feed-forward component to DKD pathogenesis.

1UT Health Science Center San Antonio, San Antonio, TX, [email protected] 2University of Texas Medical Branch Office of University Advancement: The University of Texas Medical Branch at Galveston Development Office 3UT Southwestern: The University of Texas Southwestern Medical Center 4The University of Texas Health Science Center at San Antonio

COVID-19, with persistent and new onset of symptoms such as fatigue, post-exertional malaise, and cognitive dysfunction that last for months and impact everyday functioning, is referred to as Long COVID under the general category of post-acute sequelae of SARS-CoV-2 infection (PASC). PASC is highly heterogenous and may be associated with multisystem tissue damage/dysfunction including acute encephalitis, cardiopulmonary syndromes, fibrosis, hepatobiliary damages, gastrointestinal dysregulation, myocardial infarction, neuromuscular syndromes, neuropsychiatric disorders, pulmonary damage, renal failure, stroke, and vascular endothelial dysregulation. A better understanding of the pathophysiologic mechanisms underlying PASC is essential to guide prevention and treatment. This review addresses potential mechanisms and hypotheses that connect SARS-CoV-2 infection to long-term health consequences. Comparisons between PASC and other virus-initiated chronic syndromes such as myalgic encephalomyelitis/chronic fatigue syndrome and postural orthostatic tachycardia syndrome will be addressed. Aligning symptoms with other chronic syndromes and identifying potentially regulated common underlining pathways may be necessary for understanding the true nature of PASC. The discussed contributors to PASC symptoms include sequelae from acute SARS-CoV-2 injury to one or more organs, persistent reservoirs of the replicating virus or its remnants in several tissues, re-activation of latent pathogens such as Epstein-Barr and herpes viruses in COVID-19 immune-dysregulated tissue environment, SARS-CoV-2 interactions with host microbiome/virome communities, clotting/coagulation dysregulation, dysfunctional brainstem/vagus nerve signaling, dysautonomia or autonomic dysfunction, ongoing activity of primed immune cells, and autoimmunity due to molecular mimicry between pathogen and host proteins. The individualized nature of PASC symptoms suggests that different therapeutic approaches may be required to best manage specific patients.

Summary The most abundant cellular divalent cations, Mg2+ (mM) and Ca2+ (nM-μM), antagonistically regulate divergent metabolic pathways with several orders of magnitude affinity preference, but the physiological significance of this competition remains elusive. In mice consuming a Western diet, genetic ablation of the mitochondrial Mg2+ channel Mrs2 prevents weight gain, enhances mitochondrial activity, decreases fat accumulation in the liver, and causes prominent browning of white adipose. Mrs2 deficiency restrains citrate efflux from the mitochondria, making it unavailable to support de novo lipogenesis. As citrate is an endogenous Mg2+ chelator, this may represent an adaptive response to a perceived deficit of the cation. Transcriptional profiling of liver and white adipose reveals higher expression of genes involved in glycolysis, β-oxidation, thermogenesis, and HIF-1α-targets, in Mrs2−/− mice that are further enhanced under Western-diet-associated metabolic stress. Thus, lowering mMg2+ promotes metabolism and dampens diet-induced obesity and metabolic syndrome.

SARS-CoV-2 is a newly identified coronavirus that causes the respiratory disease called coronavirus disease 2019 (COVID-19). With an urgent need for therapeutics, we lack a full understanding of the molecular basis of SARS-CoV-2-induced cellular damage and disease progression. Here, we conducted transcriptomic analysis of human PBMCs, identified significant changes in mitochondrial, ion channel, and protein quality-control gene products. SARS-CoV-2 proteins selectively target cellular organelle compartments, including the endoplasmic reticulum and mitochondria. M-protein, NSP6, ORF3A, ORF9C, and ORF10 bind to mitochondrial PTP complex components cyclophilin D, SPG-7, ANT, ATP synthase, and a previously undescribed CCDC58 (coiled-coil domain containing protein 58). Knockdown of CCDC58 or mPTP blocker cyclosporin A pretreatment enhances mitochondrial Ca2+ retention capacity and bioenergetics. SARS-CoV-2 infection exacerbates cardiomyocyte autophagy and promotes cell death that was suppressed by cyclosporin A treatment. Our finengs reveal that SARS-CoV-2 viral proteins suppress cardiomyocyte mitochondrial function that disrupts cardiomyocyte Ca2+ cycling and cell viability.

Background The mechanisms underlying long-term sequelae after AKI remain unclear. Vessel instability, an early response to endothelial injury, may reflect a shared mechanism and early trigger for CKD and heart failure.Methods To investigate whether plasma angiopoietins, markers of vessel homeostasis, are associated with CKD progression and heart failure admissions after hospitalization in patients with and without AKI, we conducted a prospective cohort study to analyze the balance between angiopoietin-1 (Angpt-1), which maintains vessel stability, and angiopoietin-2 (Angpt-2), which increases vessel destabilization. Three months after discharge, we evaluated the associations between angiopoietins and development of the primary outcomes of CKD progression and heart failure and the secondary outcome of all-cause mortality 3 months after discharge or later.Results Median age for the 1503 participants was 65.8 years; 746 (50%) had AKI. Compared with the lowest quartile, the highest quartile of the Angpt-1:Angpt-2 ratio was associated with 72% lower risk of CKD progression (adjusted hazard ratio [aHR], 0.28; 95% confidence interval [CI], 0.15 to 0.51), 94% lower risk of heart failure (aHR, 0.06; 95% CI, 0.02 to 0.15), and 82% lower risk of mortality (aHR, 0.18; 95% CI, 0.09 to 0.35) for those with AKI. Among those without AKI, the highest quartile of Angpt-1:Angpt-2 ratio was associated with 71% lower risk of heart failure (aHR, 0.29; 95% CI, 0.12 to 0.69) and 68% less mortality (aHR, 0.32; 95% CI, 0.15 to 0.68). There were no associations with CKD progression. Conclusions A higher Angpt-1:Angpt-2 ratio was strongly associated with less CKD progression, heart failure, and mortality in the setting of AKI.

Diabetic kidney disease is the leading cause of kidney failure worldwide; in the USA, it accounts for over 50% of individuals entering dialysis or transplant programmes. Unlike other complications of diabetes, the prevalence of diabetic kidney disease has failed to decline over the past 30 years. Hyperglycaemia is the primary aetiological factor responsible for the development of diabetic kidney disease. Once hyperglycaemia becomes established, multiple pathophysiological disturbances, including hypertension, altered tubuloglomerular feedback, renal hypoxia, lipotoxicity, podocyte injury, inflammation, mitochondrial dysfunction, impaired autophagy and increased activity of the sodium-hydrogen exchanger, contribute to progressive glomerular sclerosis and the decline in glomerular filtration rate. The quantitative contribution of each of these abnormalities to the progression of diabetic kidney disease, as well as their role in type 1 and type 2 diabetes mellitus, remains to be determined. Sodium-glucose co-transporter 2 (SGLT2) inhibitors have a beneficial impact on many of these pathophysiological abnormalities; however, as several pathophysiological disturbances contribute to the onset and progression of diabetic kidney disease, multiple agents used in combination will likely be required to slow the progression of disease effectively.

ImportanceAmong patients who had acute kidney injury (AKI) during hospitalization, there is a need to improve risk prediction such that those at highest risk for subsequent loss of kidney function are identified for appropriate follow-up.ObjectiveTo evaluate the association of post-AKI proteinuria with increased risk of future loss of renal function.Design, Setting, and ParticipantsThe Assessment, Serial Evaluation, and Subsequent Sequelae in Acute Kidney Injury (ASSESS-AKI) Study was a multicenter prospective cohort study including 4 clinical centers in North America included 1538 patients enrolled 3 months after hospital discharge between December 2009 and February 2015.ExposuresUrine albumin-to-creatinine ratio (ACR) quantified 3 months after hospital discharge.Main Outcomes and MeasuresKidney disease progression defined as halving of estimated glomerular filtration rate (eGFR) or end-stage renal disease.ResultsOf the 1538 participants, 769 (50%) had AKI durring hospitalization. The baseline study visit took place at a mean (SD) 91 (23) days after discharge. The mean (SD) age was 65 (13) years; the median eGFR was 68 mL/min/1.73 m2; and the median urine ACR was 15 mg/g. Overall, 547 (37%) study participants were women and 195 (13%) were black. After a median follow-up of 4.7 years, 138 (9%) participants had kidney disease progression. Higher post-AKI urine ACR level was associated with increased risk of kidney disease progression (hazard ratio [HR], 1.53 for each doubling; 95% CI, 1.45-1.62), and urine ACR measurement was a strong discriminator for future kidney disease progression (C statistic, 0.82). The performance of urine ACR was stronger in patients who had had AKI than in those who had not (C statistic, 0.70). A comprehensive model of clinical risk factors (eGFR, blood pressure, and demographics) including ACR provided better discrimination for predicting kidney disease progression after hospital discharge among those who had had AKI (C statistic, 0.85) vs those who had not (C statistic, 0.76). In the entire matched cohort, after taking into account urine ACR, eGFR, demographics, and traditional chronic kidney risk factors determined 3 months after discharge, AKI (HR, 1.46; 95% CI, 0.51-4.13 for AKI vs non-AKI) or severity of AKI (HR, 1.54; 95% CI, 0.50-4.72 for AKI stage 1 vs non-AKI; HR, 0.56; 95% CI, 0.07-4.84 for AKI stage 2 vs non-AKI; HR, 2.24; 95% CI, 0.33-15.29 for AKI stage 3 vs non-AKI) was not independently associated with more rapid kidney disease progression.Conclusions and RelevanceProteinuria level is a valuable risk-stratification tool in the post-AKI period. These results suggest there should be more widespread and routine quantification of proteinuria after hospitalized AKI.

Mg2+ is the most abundant divalent cation in metazoans and an essential cofactor for ATP, nucleic acids, and countless metabolic enzymes. To understand how the spatio-temporal dynamics of intracellular Mg2+ (iMg2+) are integrated into cellular signaling, we implemented a comprehensive screen to discover regulators of iMg2+ dynamics. Lactate emerged as an activator of rapid release of Mg2+ from endoplasmic reticulum (ER) stores, which facilitates mitochondrial Mg2+ (mMg2+) uptake in multiple cell types. We demonstrate that this process is remarkably temperature sensitive and mediated through intracellular but not extracellular signals. The ER-mitochondrial Mg2+ dynamics is selectively stimulated by L-lactate. Further, we show that lactate-mediated mMg2+ entry is facilitated by Mrs2, and point mutations in the intermembrane space loop limits mMg2+ uptake. Intriguingly, suppression of mMg2+ surge alleviates inflammation-induced multi-organ failure. Together, these findings reveal that lactate mobilizes iMg2+ and links the mMg2+ transport machinery with major metabolic feedback circuits and mitochondrial bioenergetics.

Interleukin-10 (IL-10), a cytokine with anti-inflammatory effects, is produced by renal parenchymal cells and bone marrow derived cells. Both endogenous and exogenous IL-10 are protective in cisplatin-induced acute kidney injury. However, the source of endogenous IL-10 in cisplatin-induced nephrotoxicity is not clear. Bone marrow chimera experiments in IL10-KO mice indicated that bone marrow derived cells were the primary source of IL-10 in cisplatin nephrotoxicity. Cell specific deletion of IL-10 in T regulatory cells and dendritic cells was accomplished using Foxp3 and CD11c driven cre recombination in IL10flox/flox mice, respectively. Upon treatment with cisplatin, both the IL10flox/flox and the Foxp3YFP-Cre x IL10flox/flox mice developed similar degrees of kidney injury. However, mice with the dendritic cell deletion of IL-10 showed more severe structural and functional changes in the kidney compared to the IL10flox/flox mice. These results indicate that IL-10 from dendritic cells but not from T regulatory cells offers significant endogenous protection against cisplatin induced nephrotoxicity.

Nutrient stress triggers transcriptional changes that limit Ca 2+ influx into mitochondria through the MCU.