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Birkelo BC, Koyner JL, Ostermann M, Bhatraju PK. The Road to Precision Medicine for Acute Kidney Injury. Crit Care Med 2024; 52:1127-1137. [PMID: 38869385 DOI: 10.1097/ccm.0000000000006328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
OBJECTIVES Acute kidney injury (AKI) is a common form of organ dysfunction in the ICU. AKI is associated with adverse short- and long-term outcomes, including high mortality rates, which have not measurably improved over the past decade. This review summarizes the available literature examining the evidence of the need for precision medicine in AKI in critical illness, highlights the current evidence for heterogeneity in the field of AKI, discusses the progress made in advancing precision in AKI, and provides a roadmap for studying precision-guided care in AKI. DATA SOURCES Medical literature regarding topics relevant to precision medicine in AKI, including AKI definitions, epidemiology, and outcomes, novel AKI biomarkers, studies of electronic health records (EHRs), clinical trial design, and observational studies of kidney biopsies in patients with AKI. STUDY SELECTION English language observational studies, randomized clinical trials, reviews, professional society recommendations, and guidelines on areas related to precision medicine in AKI. DATA EXTRACTION Relevant study results, statements, and guidelines were qualitatively assessed and narratively synthesized. DATA SYNTHESIS We synthesized relevant study results, professional society recommendations, and guidelines in this discussion. CONCLUSIONS AKI is a syndrome that encompasses a wide range of underlying pathologies, and this heterogeneity has hindered the development of novel therapeutics for AKI. Wide-ranging efforts to improve precision in AKI have included the validation of novel biomarkers of AKI, leveraging EHRs for disease classification, and phenotyping of tubular secretory clearance. Ongoing efforts such as the Kidney Precision Medicine Project, identifying subphenotypes in AKI, and optimizing clinical trials and endpoints all have great promise in advancing precision medicine in AKI.
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Affiliation(s)
- Bethany C Birkelo
- Division of Nephrology, Department of Medicine, University of Minnesota, Minneapolis, MN
| | - Jay L Koyner
- Section of Nephrology, Department of Medicine, University of Chicago, Chicago, IL
| | - Marlies Ostermann
- Department of Critical Care and Nephrology, King's College London, Guy's and St. Thomas' Hospital, London, United Kingdom
| | - Pavan K Bhatraju
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Washington, Seattle, WA
- Kidney Research Institute, University of Washington, Seattle, WA
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Maeda A, Inokuchi R, Bellomo R, Doi K. Heterogeneity in the definition of major adverse kidney events: a scoping review. Intensive Care Med 2024:10.1007/s00134-024-07480-x. [PMID: 38801518 DOI: 10.1007/s00134-024-07480-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 05/03/2024] [Indexed: 05/29/2024]
Abstract
Acute kidney injury (AKI) is associated with persistent renal dysfunction, the receipt of dialysis, dialysis dependence, and mortality. Accordingly, the concept of major adverse kidney events (MAKE) has been adopted as an endpoint for assessing the impact of AKI. However, applied criteria or observation periods for operationalizing MAKE appear to vary across studies. To evaluate this heterogeneity for MAKE evaluation, we performed a systematic scoping review of studies that employed MAKE as an AKI endpoint. Four major academic databases were searched, and we identified 122 studies with increasing numbers over time. We found marked heterogeneity in applied criteria and observation periods for MAKE across these studies, with some even lacking a description of criteria. Moreover, 13 different observation periods were employed, with 30 days and 90 days as the most common. Persistent renal dysfunction was evaluated by estimated glomerular filtration rate (34%) or serum creatinine concentration (48%); however, 37 different definitions for this component were employed in terms of parameters, cut-off criteria, and assessment periods. The definition for the dialysis component also showed significant heterogeneity regarding assessment periods and duration of dialysis requirement (chronic vs temporary). Finally, MAKE rates could vary by 7% [interquartile range: 1.7-16.7%] with different observation periods or by 36.4% with different dialysis component definitions. Our findings revealed marked heterogeneity in MAKE definitions, particularly regarding component assessment and observation periods. Dedicated discussion is needed to establish uniform and acceptable standards to operationalize MAKE in terms of selection and applied criteria of components, observation period, and reporting criteria for future trials on AKI and related conditions.
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Affiliation(s)
- Akinori Maeda
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia
- Department of Emergency and Critical Care Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Ryota Inokuchi
- Department of Emergency and Critical Care Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
- Department of Clinical Engineering, The University of Tokyo Hospital, Tokyo, Japan
| | - Rinaldo Bellomo
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia
- Data Analytics Research and Evaluation Centre, The University of Melbourne and Austin Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia
- Australian and New Zealand Intensive Care Research Centre, Monash University, Melbourne, VIC, Australia
- Department of Intensive Care, The Royal Melbourne Hospital, Melbourne, Australia
| | - Kent Doi
- Department of Emergency and Critical Care Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
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3
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Siew ED. Do Novel Biomarkers Have Utility in the Diagnosis and Prognosis of AKI?: Commentary. KIDNEY360 2023; 4:1670-1671. [PMID: 38153791 PMCID: PMC10917109 DOI: 10.34067/kid.0000000000000240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 07/31/2023] [Indexed: 12/30/2023]
Affiliation(s)
- Edward D Siew
- Division of Nephrology and Hypertension, Vanderbilt Center for Kidney Disease (VCKD) and Integrated Program for Acute Kidney Injury (AKI), Vanderbilt University Medical Center, Nashville, Tennessee and Tennessee Valley Health Systems (TVHS), Nashville Veterans Affairs Hospital, Tennessee
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Bullen AL, Fregoso A, Ascher SB, Shlipak MG, Ix JH, Rifkin DE. Markers of Kidney Tubule Dysfunction and Major Adverse Kidney Events. Nephron Clin Pract 2023; 147:713-716. [PMID: 37524063 DOI: 10.1159/000531946] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/09/2023] [Indexed: 08/02/2023] Open
Abstract
BACKGROUND Serum creatinine and albuminuria are primary markers of glomerular function and injury, respectively. Tubular secretion, acid-base homeostasis, protein reabsorption, among other tubular functions, are largely ignored. This mini-review aimed to discuss how two tubular functions, secretion, and acid-base homeostasis are associated with major adverse kidney events (MAKEs). SUMMARY Proximal tubular secretion is an essential function that allows the elimination of endogenous substances and drugs. Recently discovered endogenous markers in urine and plasma allow a noninvasive way of assessing tubular secretion markers. Several studies have found an association between these markers and a higher risk of chronic kidney disease (CKD) progression and mortality. In a study we recently performed among patients with CKD and at risk of cardiovascular events, lower tubular secretion was associated with an increased risk of acute kidney injury and metabolic acidosis, independent of baseline eGFR and albuminuria. The kidney tubules also play a crucial role in acid-base homeostasis. Although the standard clinical assessment of acidosis consists of measuring serum bicarbonate, urinary ammonium excretion decreases before over metabolic acidosis. Urinary ammonium excretion is associated with CKD progression, a higher risk of kidney failure, and an increased mortality risk, independent of baseline eGFR and albuminuria. KEY MESSAGES Novel biomarkers of kidney tubular health consistently associate with MAKEs, above and beyond baseline eGFR, albuminuria, and other CKD risk factors. Tubular markers may provide new opportunities to improve kidney prognosis, drug dosing, and monitoring for adverse events.
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Affiliation(s)
- Alexander L Bullen
- Nephrology Section, Veterans Affairs San Diego Healthcare System, La Jolla, California, USA
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, San Diego, California, USA
| | - Alma Fregoso
- School of Medicine, University of California San Diego, San Diego, California, USA
| | - Simon B Ascher
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, California, USA
- Division of Hospital Medicine, University of California Davis, Sacramento, California, USA
| | - Michael G Shlipak
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, California, USA
| | - Joachim H Ix
- Nephrology Section, Veterans Affairs San Diego Healthcare System, La Jolla, California, USA
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, San Diego, California, USA
| | - Dena E Rifkin
- Nephrology Section, Veterans Affairs San Diego Healthcare System, La Jolla, California, USA
- Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, San Diego, California, USA
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5
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Liu C, Liu Y, Wang C, Guo Y, Cheng Y, Qian H, Zhao Y. Lycopene-Loaded Bilosomes Ameliorate High-Fat Diet-Induced Chronic Nephritis in Mice through the TLR4/MyD88 Inflammatory Pathway. Foods 2022; 11:foods11193042. [PMID: 36230117 PMCID: PMC9564075 DOI: 10.3390/foods11193042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/06/2022] [Accepted: 09/16/2022] [Indexed: 11/27/2022] Open
Abstract
Chronic kidney disease caused by a high-fat diet (HFD)-induced metabolic syndrome has received widespread attention. Lycopene has a wide range of biological activities and can improve a variety of chronic diseases through anti-inflammatory effects. In this study, HFD-fed mice were used as a metabolic syndrome model to evaluate the protective effect of lycopene in a sustained-release vehicle (bilosomes) in the small intestine against renal injury and to determine whether the TLR4/MyD88 pathway and related metabolic pathways are involved in this process. The results showed that lycopene bilosomes alleviated HFD-induced kidney damage, as evidenced by lower serum urea nitrogen, creatinine, and uric acid levels. Histopathology studies showed that lycopene bilosomes attenuated HFD-induced tubular cell and glomerular injury. In addition, Elisa, RT-PCR, and Western blotting results showed that lycopene bilosomes also reduced the expression of inflammatory factors such as TLR4, MyD88, NF-kB, TNF-a, and IL-6 in mouse kidneys. The mechanism was to attenuate renal inflammatory response by inhibiting the TLR4/MyD88 inflammatory pathway. These findings suggested that lycopene can alleviate nephritis and metabolic disorders caused by HFD, inhibiting the TLR4/MyD88 inflammatory pathway and its downstream pro-inflammatory cytokines and further regulating the vitamin K metabolism, beta-alanine metabolism, and glutathione metabolism pathways to relieve chronic nephritis.
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Affiliation(s)
- Chang Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, No.1800 Lihu Avenue, Wuxi 214122, China
| | - Yu Liu
- Wuxi 9th People’s Hospital Affiliated to Soochow University, Wuxi 214122, China
| | - Ciwan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, No.1800 Lihu Avenue, Wuxi 214122, China
| | - Yahui Guo
- State Key Laboratory of Food Science and Technology, Jiangnan University, No.1800 Lihu Avenue, Wuxi 214122, China
| | - Yuliang Cheng
- State Key Laboratory of Food Science and Technology, Jiangnan University, No.1800 Lihu Avenue, Wuxi 214122, China
| | - He Qian
- State Key Laboratory of Food Science and Technology, Jiangnan University, No.1800 Lihu Avenue, Wuxi 214122, China
| | - Yong Zhao
- Thoracic and Cardiac Surgery, Affiliated Hospital of Jiangnan University, No.1000, He Feng Road, Wuxi 214122, China
- Correspondence:
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Thompson LE, Joy MS. Endogenous markers of kidney function and renal drug clearance processes of filtration, secretion, and reabsorption. CURRENT OPINION IN TOXICOLOGY 2022; 31:100344. [PMID: 36777447 PMCID: PMC9910221 DOI: 10.1016/j.cotox.2022.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The kidneys are responsible for maintaining physiologic homeostasis. The kidneys clear a variety of drugs and other substances through passive (filtration) and active processes that utilize transport proteins. Renal clearance is comprised of the processes of glomerular filtration, tubular secretion, and tubular reabsorption. Endogenous biomarkers, such as creatinine and cystatin C, are routinely used to estimate renal clearance. Understanding the contributing components of renal function and clearance, through the use of biomarkers, is necessary in elucidating the renal pharmacology of drugs and other substances. While exogenous markers of kidney function have been known for decades, several complexities have limited their usage. Several endogenous markers are being evaluated and hold promise to elucidate the individual components of kidney function that represent filtration, secretion, and reabsorption.
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Affiliation(s)
- Lauren E. Thompson
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Melanie S. Joy
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA,Division of Renal Diseases, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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7
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Metabolic mechanisms of acute proximal tubular injury. Pflugers Arch 2022; 474:813-827. [PMID: 35567641 PMCID: PMC9338906 DOI: 10.1007/s00424-022-02701-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/12/2022] [Accepted: 05/02/2022] [Indexed: 12/11/2022]
Abstract
Damage to the proximal tubule (PT) is the most frequent cause of acute kidney injury (AKI) in humans. Diagnostic and treatment options for AKI are currently limited, and a deeper understanding of pathogenic mechanisms at a cellular level is required to rectify this situation. Metabolism in the PT is complex and closely coupled to solute transport function. Recent studies have shown that major changes in PT metabolism occur during AKI and have highlighted some potential targets for intervention. However, translating these insights into effective new therapies still represents a substantial challenge. In this article, in addition to providing a brief overview of the current state of the field, we will highlight three emerging areas that we feel are worthy of greater attention. First, we will discuss the role of axial heterogeneity in cellular function along the PT in determining baseline susceptibility to different metabolic hits. Second, we will emphasize that elucidating insult specific pathogenic mechanisms will likely be critical in devising more personalized treatments for AKI. Finally, we will argue that uncovering links between tubular metabolism and whole-body homeostasis will identify new strategies to try to reduce the considerable morbidity and mortality associated with AKI. These concepts will be illustrated by examples of recent studies emanating from the authors' laboratories and performed under the auspices of the Swiss National Competence Center for Kidney Research (NCCR Kidney.ch).
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Davidson JA, Robison J, Khailova L, Frank BS, Jaggers J, Ing RJ, Lawson S, Iguidbashian J, Ali E, Treece A, Soranno DE, Osorio-Lujan S, Klawitter J. Metabolomic profiling demonstrates evidence for kidney and urine metabolic dysregulation in a piglet model of cardiac surgery-induced acute kidney injury. Am J Physiol Renal Physiol 2022; 323:F20-F32. [PMID: 35532069 PMCID: PMC9236877 DOI: 10.1152/ajprenal.00039.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Acute kidney injury (AKI) is a common cause of morbidity after congenital heart disease surgery. Progress on diagnosis and therapy remains limited, however, in part due to poor mechanistic understanding and a lack of relevant translational models. Metabolomic approaches could help identify novel mechanisms of injury and potential therapeutic targets. In the present study, we used a piglet model of cardiopulmonary bypass with deep hypothermic circulatory arrest (CPB/DHCA) and targeted metabolic profiling of kidney tissue, urine, and serum to evaluate metabolic changes specific to animals with histological acute kidney injury. CPB/DHCA animals with acute kidney injury were compared with those without acute kidney injury and mechanically ventilated controls. Acute kidney injury occurred in 10 of 20 CPB/DHCA animals 4 h after CPB/DHCA and 0 of 7 control animals. Injured kidneys showed a distinct tissue metabolic profile compared with uninjured kidneys (R2 = 0.93, Q2 = 0.53), with evidence of dysregulated tryptophan and purine metabolism. Nine urine metabolites differed significantly in animals with acute kidney injury with a pattern suggestive of increased aerobic glycolysis. Dysregulated metabolites in kidney tissue and urine did not overlap. CPB/DHCA strongly affected the serum metabolic profile, with only one metabolite that differed significantly with acute kidney injury (pyroglutamic acid, a marker of oxidative stress). In conclusion, based on these findings, kidney tryptophan and purine metabolism are candidates for further mechanistic and therapeutic investigation. Urine biomarkers of aerobic glycolysis could help diagnose early acute kidney injury after CPB/DHCA and warrant further evaluation. The serum metabolites measured at this early time point did not strongly differentiate based on acute kidney injury. NEW & NOTEWORTHY This project explored the metabolic underpinnings of postoperative acute kidney injury (AKI) following pediatric cardiac surgery in a translationally relevant large animal model of cardiopulmonary bypass with deep hypothermic circulatory arrest. Here, we present novel evidence for dysregulated tryptophan catabolism and purine catabolism in kidney tissue and increased urinary glycolysis intermediates in animals who developed histological AKI. These pathways represent potential diagnostic and therapeutic targets for postoperative AKI in this high-risk population.
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Affiliation(s)
- Jesse A Davidson
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Justin Robison
- Department of Pediatrics, Washington University in St. Louis School of Medicine, St. Louis, United States
| | - Ludmila Khailova
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Benjamin S Frank
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - James Jaggers
- Department of Surgery, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Richard J Ing
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - Scott Lawson
- Heart Institute, Children's Hospital Colorado, Aurora, CO, United States
| | - John Iguidbashian
- Department of Surgery, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Eiman Ali
- Heart Institute, Children's Hospital Colorado, Aurora, CO, United States
| | - Amy Treece
- Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - Danielle E Soranno
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Suzanne Osorio-Lujan
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Jelena Klawitter
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
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Sathe NA, Bhatraju PK, Mikacenic C, Morrell ED, Mabrey FL, Liles WC, Wurfel MM. Relationships Between Age, Soluble Triggering Receptor Expressed on Myeloid Cells-1 (sTREM-1), and Mortality Among Critically Ill Adults: A Cohort Study. Shock 2022; 57:205-211. [PMID: 34812186 PMCID: PMC8969235 DOI: 10.1097/shk.0000000000001888] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Innate immune dysregulation may contribute to age-related differences in outcomes among critically ill adults. Soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) is an important innate immune marker with prognostic value in sepsis, but age-related differences have not been studied. METHODS This was a prospective cohort from a large tertiary care hospital enrolling adults from both medical and trauma-surgical intensive care units (ICUs). Plasma sTREM-1 was measured in participants within 24 h of ICU admission. We analyzed associations between age (≤50 and >50 years) and sTREM-1 using linear regression. We then examined associations between sTREM-1 and both 28-day mortality and persistent organ dysfunction (defined as need for dialysis, vasopressors, or invasive mechanical ventilation) 7 days following admission using relative risk regression. RESULTS Of 231 critically ill adults, older patients (n = 122) had higher prevalence of chronic disease and sepsis on enrollment than younger patients, but acute illness severity was similar. Age over 50 was associated with 27% higher sTREM-1 concentrations (95% CI 6%-53%), adjusted for sex and Charlson comorbidity index (CCI). Two-fold higher sTREM-1 was associated with 2.42-fold higher risk for mortality (95% CI 1.57, 3.73) and 1.86-fold higher risk for persistent organ dysfunction (95% CI 1.45, 2.39), adjusted for sex, CCI, and age. CONCLUSIONS sTREM-1 was elevated among critically ill older adults, and strongly associated with both death and persistent organ dysfunction. Immune responses associated with sTREM-1 may contribute to age-related differences in ICU outcomes, warranting further study as a potential therapeutic target in older adults.
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Affiliation(s)
- Neha A. Sathe
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Washington, Seattle, WA
| | - Pavan K. Bhatraju
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Washington, Seattle, WA
- Sepsis Center of Research Excellence-University of Washington (SCORE-UW)
| | - Carmen Mikacenic
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Washington, Seattle, WA
- Benaroya Research Institute, Seattle, WA
| | - Eric D. Morrell
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Washington, Seattle, WA
- Sepsis Center of Research Excellence-University of Washington (SCORE-UW)
| | - F. Linzee Mabrey
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Washington, Seattle, WA
| | - W. Conrad Liles
- Sepsis Center of Research Excellence-University of Washington (SCORE-UW)
- Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA
| | - Mark M. Wurfel
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Washington, Seattle, WA
- Sepsis Center of Research Excellence-University of Washington (SCORE-UW)
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Wee HN, Liu JJ, Ching J, Kovalik JP, Lim SC. The Kynurenine Pathway in Acute Kidney Injury and Chronic Kidney Disease. Am J Nephrol 2021; 52:771-787. [PMID: 34753140 PMCID: PMC8743908 DOI: 10.1159/000519811] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 09/15/2021] [Indexed: 12/12/2022]
Abstract
BACKGROUND The kynurenine pathway (KP) is the major catabolic pathway for tryptophan degradation. The KP plays an important role as the sole de novo nicotinamide adenine dinucleotide (NAD+) biosynthetic pathway in normal human physiology and functions as a counter-regulatory mechanism to mitigate immune responses during inflammation. Although the KP has been implicated in a variety of disorders including Huntington's disease, seizures, cardiovascular disease, and osteoporosis, its role in renal diseases is seldom discussed. SUMMARY This review summarizes the roles of the KP and its metabolites in acute kidney injury (AKI) and chronic kidney disease (CKD) based on current literature evidence. Metabolomics studies demonstrated that the KP metabolites were significantly altered in patients and animal models with AKI or CKD. The diagnostic and prognostic values of the KP metabolites in AKI and CKD were highlighted in cross-sectional and longitudinal human observational studies. The biological impact of the KP on the pathophysiology of AKI and CKD has been studied in experimental models of different etiologies. In particular, the activation of the KP was found to confer protection in animal models of glomerulonephritis, and its immunomodulatory mechanism may involve the regulation of T cell subsets such as Th17 and regulatory T cells. Manipulation of the KP to increase NAD+ production or diversion toward specific KP metabolites was also found to be beneficial in animal models of AKI. Key Messages: KP metabolites are reported to be dysregulated in human observational and animal experimental studies of AKI and CKD. In AKI, the magnitude and direction of changes in the KP depend on the etiology of the damage. In CKD, KP metabolites are altered with the onset and progression of CKD all the way to advanced stages of the disease, including uremia and its related vascular complications. The activation of the KP and diversion to specific sub-branches are currently being explored as therapeutic strategies in these diseases, especially with regards to the immunomodulatory effects of certain KP metabolites. Further elucidation of the KP may hold promise for the development of biomarkers and targeted therapies for these kidney diseases.
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Affiliation(s)
| | - Jian-Jun Liu
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore, Singapore
| | - Jianhong Ching
- Duke-NUS Medical School, Singapore, Singapore
- KK Research Centre, KK Women's and Children's Hospital, Singapore, Singapore
| | | | - Su Chi Lim
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore, Singapore
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
- Diabetes Centre, Admiralty Medical Centre, Singapore, Singapore
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