Acute kidney injury (AKI) is caused by a variety of diseases, which leads to acute renal function decline, azotemia, water and electrolyte disorders and acid-base balance disorders. Metabolomics is a research method that can quantitatively analyze all metabolites in an organism and find the relative relationship between metabolites and physiological and pathological changes. In recent years, several metabolites screened based on metabolomics have been proposed as potential biomarkers to assess the early development and prognosis of AKI and for the discovery of unknown potential therapeutic targets. Based on metabolomics, this paper reviews the risk prediction, early diagnosis, disease monitoring, prognosis assessment and the application of corresponding drugs for AKI, so as to provide reference for precision medicine.
Humans ; Acute Kidney Injury/metabolism* ; Metabolomics ; Prognosis ; Biomarkers ; Precision Medicine

Acute kidney injury (AKI) refers to a clinical syndrome in which renal function declines rapidly in a short period of time caused by various pathological factors. During the development of AKI, renal tubules with the functions of reabsorption and excretion are prone to cell death due to external pathological stimuli, which is an important cause of impaired renal function. In recent years, a variety of new cell death pathways have been gradually recognized. Researchers have now found that regulated cell death (RCD), such as necroptosis, pyroptosis and ferroptosis, are important regulatory mechanisms of AKI. This article will summarize the research advances of various types of RCD involved in the process of AKI, aiming to deepen the understanding of AKI and provide innovative thoughts for the clinical treatment of AKI.
Acute Kidney Injury/metabolism* ; Cell Death ; Humans ; Kidney/metabolism* ; Necroptosis ; Necrosis/pathology* ; Regulated Cell Death

Klotho is highly expressed in the kidney, while soluble Klotho is detectable in the blood, urine, and cerebrospinal fluid, and has multiple hormone-like functions. The role of Klotho in kidney injury has attracted more and more attentions from researchers. Emerging evidence revealed that the transient deficiency of Klotho is an early event of acute kidney injury (AKI), whereas, in chronic kidney disease, this deficiency is sustained not only in the kidney, but also in other organ systems. Therefore, Klotho could be a potential biomarker for early diagnosis of AKI, as well as for its progression to chronic kidney disease. Moreover, Klotho might have therapeutic value to renal injury. Nevertheless, there are only few studies on the involvement of Klotho in post AKI repair. This review focused on the role of Klotho in not only kidney injury, but also its repair, in particular the relationship between Klotho and cell fate (autophagy/apoptosis/necrosis), repair/regeneration, Wnt/β-catenin and erythropoietin receptor, one of the Klotho effectors.
Acute Kidney Injury ; metabolism ; Biomarkers ; Disease Progression ; Glucuronidase ; physiology ; Humans ; Kidney ; metabolism ; pathology ; Signal Transduction

OBJECTIVE: To investigate protective effect of Cordyceps sinensis (CS) through autophagy-associated adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway in acute kidney injury (AKI)-induced acute lung injury (ALI). METHODS: Forty-eight male Sprague-Dawley rats were divided into 4 groups according to a random number table, including the normal saline (NS)-treated sham group (sham group), NS-treated ischemia reperfusion injury (IRI) group (IRI group), and low- (5 g/kg·d) and high-dose (10 g/kg·d) CS-treated IRI groups (CS1 and CS2 groups), 12 rats in each group. Nephrectomy of the right kidney was performed on the IRI rat model that was subjected to 60 min of left renal pedicle occlusion followed by 12, 24, 48, and 72 h of reperfusion. The wet-to-dry (W/D) ratio of lung, levels of serum creatinine (Scr), blood urea nitrogen (BUN), inflammatory cytokines such as interleukin- β and tumor necrosis factor- α, and biomarkers of oxidative stress such as superoxide dismutase, malonaldehyde (MDA) and myeloperoxidase (MPO), were assayed. Histological examinations were conducted to determine damage of tissues in the kidney and lung. The protein expressions of light chain 3 II/light chain 3 I (LC3-II/LC3-I), uncoordinated-51-like kinase 1 (ULK1), P62, AMPK and mTOR were measured by Western blot and immunohistochemistry, respectively. RESULTS: The renal IRI induced pulmonary injury following AKI, resulting in significant increases in W/D ratio of lung, and the levels of Scr, BUN, inflammatory cytokines, MDA and MPO (P<0.01); all of these were reduced in the CS groups (P<0.05 or P<0.01). Compared with the IRI groups, the expression levels of P62 and mTOR were significantly lower (P<0.05 or P<0.01), while those of LC3-II/LC3-I, ULK1, and AMPK were significantly higher in the CS2 group (P<0.05 or P<0.01). CONCLUSION CS had a potential in treating lung injury following renal IRI through activation of the autophagy-related AMPK/mTOR signaling pathway in AKI-induced ALI.
Rats ; Male ; Animals ; AMP-Activated Protein Kinases/metabolism* ; Cordyceps/metabolism* ; Rats, Sprague-Dawley ; Kidney/pathology* ; Acute Kidney Injury/metabolism* ; Signal Transduction ; TOR Serine-Threonine Kinases/metabolism* ; Reperfusion Injury/metabolism* ; Cytokines/metabolism* ; Acute Lung Injury/drug therapy* ; Mammals/metabolism*

Histone acetylation is one of the epigenetic modifications. Histone acetylation, which is catalyzed by histone acetyltransferases and negatively regulated by histone deacetylases, plays an important role in a variety of cellular physiological and pathophysiological processes. Recent studies have shown that histone deacetylases are involved in a variety of pathophysiological responses to acute kidney injury, such as apoptosis, dedifferentiation, proliferation and regeneration. This article reviews the role and underlying mechanism of histone deacetylases in acute kidney injury induced by ischemia reperfusion, nephrotoxicants, sepsis and rhabdomyolysis.
Acetylation ; Acute Kidney Injury ; Histone Acetyltransferases/metabolism* ; Histone Deacetylases/metabolism* ; Humans ; Protein Processing, Post-Translational

Acute kidney injury (AKI) is a common clinical syndrome and an independent risk factor of chronic kidney disease and end-stage renal failure. At present, the treatments of AKI are still very limited and the morbidity and mortality of AKI are rising. Non-coding RNAs (ncRNAs), including microRNAs, long non-coding RNAs and circular RNAs (circRNAs), are RNAs that are transcribed from the genome, but not translated into proteins. It has been widely reported that ncRNA is involved in AKI caused by ischemia reperfusion injury (IRI), drugs and sepsis through different molecular biological mechanisms, such as apoptosis and oxidative stress response. Therefore, ncRNAs are expected to become a new target for clinical prevention and treatment of AKI and a new biomarker for early warning of the occurrence and prognosis of AKI. Here, the role and mechanism of ncRNA in AKI and the research progress of ncRNA as biomarkers are reviewed.
Acute Kidney Injury/metabolism* ; Humans ; MicroRNAs/metabolism* ; RNA, Circular ; RNA, Long Noncoding/genetics* ; RNA, Untranslated/genetics* ; Reperfusion Injury/genetics*

Acute kidney injury is a serious global health problem and determinant of morbidity and mortality. Recent advancements in the field of stem cell research raise hopes for stem cell-based regenerative approaches to treat acute kidney diseases. In this review, the authors summarized the latest research advances of the adult resident renal progenitor cells (ARPCs) on kidney repair, the role of ARPCs on tubular regeneration after acute kidney injury, the current understanding of the mechanisms related to ARPC activation and modulation, as well as the challenges that remain to be faced.
Acute Kidney Injury ; physiopathology ; Antigens, CD ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Humans ; Kidney ; physiopathology ; Kidney Tubules ; physiopathology ; Receptors, CXCR ; metabolism ; Regeneration ; physiology ; Reperfusion Injury ; physiopathology ; Stem Cells ; physiology

Acute kidney injury (AKI) is a common critical clinical disease characterized by a sharp decline of renal function. Ischemia-reperfusion (IR) is one of the main causes of AKI. The mortality of AKI remains high due to the lack of early diagnosis and cause specific treatment. IR rapidly initiates innate immune responses, activates complement and innate immune cells, releasing a large number of injury-related molecules such as high mobility group box-1 (HMGB1), inflammatory mediators such as caspase-3, and then recruits immune inflammatory cells including M1 macrophages (Mϕ) to the microenvironment of injury, causing apoptosis and necrosis of renal tubular epithelial cells (TECs). Dead cells and associated inflammation further activate the adaptive immune system, which not only aggravates tissue damage, but also initiates M2 Mϕ participated inflammatory clearance, tissue repair and regeneration. Mϕ, professional phagocytes, and TECs, semi-professional phagocytes, can phagocytose around damaged cells including apoptotic Mϕ and TECs, which are key innate immune cells to regulate the outcome of injury, repair or fibrosis. In recent years, it has been found that erythropoietin (EPO) not only binds to the homodimeric receptor (EPOR)₂ to induce erythropoiesis, but also binds to the heterodimeric receptor EPOR/βcR, also known as innate repair receptor, which plays renoprotective roles. Properdin is the only positive regulator in the complement activation of alternative pathway. It also can effectively identify and bind to early apoptotic T cells and facilitate phagocytic clearing by Mϕ through a non-complement activation-dependent mechanism. Our previous studies have shown that Mϕ and TECs associated with EPO and its receptors and properdin are involved in IR injury and repair, but the underlying mechanism needs to be further explored. As an important carrier of cell-to-cell signal transmission, exosomes participate in the occurrence and development of a variety of renal diseases. The role of exosomes involved in the interaction between Mϕ and TECs in IR-induced AKI is not fully defined. Based on the available results in the role of Mϕ and TECs in renal IR-induced AKI, this review discussed the role of Mϕ polarization and interaction with TECs in renal IR injury, as well as the participation of EPO and its receptors, properdin and exosomes.
Acute Kidney Injury/metabolism* ; Animals ; Epithelial Cells/metabolism* ; Humans ; Ischemia/metabolism* ; Kidney ; Macrophages/physiology* ; Mice ; Mice, Inbred C57BL ; Reperfusion ; Reperfusion Injury

Acute Kidney Injury ; chemically induced ; enzymology ; Animals ; Disease Models, Animal ; Gentamicins ; Peptidyl-Dipeptidase A ; metabolism ; Rats

OBJECTIVETo assess the kidney oxygen bioavailability in acute renal failure using blood oxygen level dependent (BOLD) magnetic resonance (MR) imaging.

METHODSTwenty-one patients with acute renal failure, including 18 patients with oliguric renal failure, 1 nonoliguric acute renal failure and 2 functional renal failure were enrolled in the study; 20 healthy subjects served as controls. All subjects received renal functional MR examination. BOLD MR imaging with 16 gradient-recalled-echoes on a 1.5-T scanner were performed. R2(*)(1/sec) values of the cortex and medulla and R2(*) ratio of the medulla to cortex (R2(*) ratio of M/C) of the renal were recorded respectively.

RESULTSThe R2(*) values of the medulla was higher than those of the cortex in controls (17.64 +/-1.86/sec vs 13.73 +/-0.49/sec, P<0.00). The R2(*) ratio of M/C in controls was 1.28 +/-0.06. The R2(*) values of the medulla (13.31 +/-4.28/sec) and cortex (12.25 +/-2.41/sec) and the R2(* ) ratio of M/C (1.01 +/-0.25) in oliguric renal failure were lower than those in controls (P <0.05). Patients with functional renal failure and nonoliguric acute renal failure had higher R2(*) values in cortex and medulla and higher R2(*) ratio of M/C than those of controls.

CONCLUSIONBOLD MRI demonstrates that decreased R2(*) values of cortex and medulla suggest lower oxygen bioavailability in acute renal failure and decreased R2(*)ratio of M/C suggests the disappearance of a steep cortico-medullary gradient of oxygen.

Acute Kidney Injury ; diagnosis ; metabolism ; physiopathology ; Adult ; Biological Availability ; Female ; Humans ; Kidney ; metabolism ; physiopathology ; Kidney Function Tests ; methods ; Magnetic Resonance Imaging ; methods ; Male ; Middle Aged ; Oxygen ; blood ; metabolism