Kidney vascular congestion exacerbates acute kidney injury in mice

Malnutrition stratified by marasmus and kwashiorkor in adult patients with heart failure

Malnutrition is classified into marasmus and kwashiorkor in children. However, the clinical significance of these aspects is unclear in adult patients with heart failure (HF). We divided 2308 adult patients with HF into four groups according to marasmus type (body mass index < 18.5 kg/m2) and kwashiorkor type (serum albumin < 3.4 g/dL) malnutrition: Group C (no malnutrition, n = 1511, 65.5%), Group M (marasmus type malnutrition, n = 133, 5.8%), Group K (kwashiorkor type malnutrition, n = 554, 24.0%) and Group MK (marasmic-kwashiorkor type malnutrition, n = 110, 4.8%). Group M showed the lowest blood pressure. Groups K and MK showed higher levels of B-type natriuretic peptide. Right atrial pressure was lowest in Groups M and MK. Kaplan-Meir analysis demonstrated that Group MK had the lowest event-free rate of all-cause death and cardiac death. In the multivariable Cox proportional hazard analysis, Groups M, K, and MK were associated with all-cause death (hazard ratio 1.790, 1.657 and 2.313, respectively) and cardiac death (hazard ratio 2.053, 1.855 and 3.001, respectively) compared to Group C as a reference. Marasmus type and kwashiorkor type malnutrition are associated with distinct profiles and high mortality, and marasmic-kwashiorkor type malnutrition has the poorest prognosis.

Renal Congestion in Heart Failure: Insights in Novel Diagnostic Modalities

Heart failure is increasingly prevalent and is estimated to increase its burden in the following years. A well-reported comorbidity of heart failure is renal dysfunction, where predominantly changes in the patient's volume status, tubular necrosis or other mechanical and neurohormonal mechanisms seem to drive this impairment. Currently, there are established biomarkers evaluating the patient's clinical status solely regarding the cardiovascular or renal system. However, as the coexistence of heart and renal failure is common and related to increased mortality and hospitalization for heart failure, it is of major importance to establish novel diagnostic techniques, which could identify patients with or at risk for cardiorenal syndrome and assist in selecting the appropriate management for these patients. Such techniques include biomarkers and imaging. In regards to biomarkers, several peptides and miRNAs indicative of renal or tubular dysfunction seem to properly identify patients with cardiorenal syndrome early on in the course of the disease, while changes in their serum levels can also be helpful in identifying response to diuretic treatment. Current and novel imaging techniques can also identify heart failure patients with early renal insufficiency and assess the volume status and the effect of treatment of each patient. Furthermore, by assessing the renal morphology, these techniques could also help identify those at risk of kidney impairment. This review aims to present all relevant clinical and trial data available in order to provide an up-to-date summary of the modalities available to properly assess cardiorenal syndrome.

Chloroquine Intervenes Nephrotoxicity of Nilotinib through Deubiquitinase USP13-Mediated Stabilization of Bcl-XL

Nephrotoxicity has become prominent due to the increase in the clinical use of nilotinib, a second-generation BCR-ABL1 inhibitor in the first-line treatment of Philadelphia chromosome-positive chronic myeloid leukemia. To date, the mechanism of nilotinib nephrotoxicity is still unknown, leading to a lack of clinical intervention strategies. Here, it is found that nilotinib could induce glomerular atrophy, renal tubular degeneration, and kidney fibrosis in an animal model. Mechanistically, nilotinib induces intrinsic apoptosis by specifically reducing the level of BCL2 like 1 (Bcl-XL) in both vascular endothelial cells and renal tubular epithelial cells, as well as in vivo. It is confirmed that chloroquine (CQ) intervenes with nilotinib-induced apoptosis and improves mitochondrial integrity, reactive oxygen species accumulation, and DNA damage by reversing the decreased Bcl-XL. The intervention effect is dependent on the alleviation of the nilotinib-induced reduction in ubiquitin specific peptidase 13 (USP13) and does not rely on autophagy inhibition. Additionally, it is found that USP13 abrogates cell apoptosis by preventing excessive ubiquitin-proteasome degradation of Bcl-XL. In conclusion, the research reveals the molecular mechanism of nilotinib's nephrotoxicity, highlighting USP13 as an important regulator of Bcl-XL stability in determining cell fate, and provides CQ analogs as a clinical intervention strategy for nilotinib's nephrotoxicity.

Cardiorenal Syndrome in the Hospital

The cardiorenal syndrome refers to a group of complex, bidirectional pathophysiological pathways involving dysfunction in both the heart and kidney. Upward of 60% of patients admitted for acute decompensated heart failure have CKD, as defined by an eGFR of <60 ml/min per 1.73 m 2 . CKD, in turn, is one of the strongest risk factors for mortality and cardiovascular events in acute decompensated heart failure. Although not well understood, the mechanisms in the cardiorenal syndrome include venous congestion, arterial underfilling, neurohormonal activation, inflammation, and endothelial dysfunction. Arterial underfilling may lead to activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, leading to sodium reabsorption and vasoconstriction. Venous congestion likely also mediates and perpetuates these maladaptive pathways. To rule out intrinsic kidney disease that is distinct from the cardiorenal syndrome, one should obtain a careful history, review longitudinal eGFR trends, assess albuminuria and proteinuria, and review the urine sediment and kidney imaging. The hallmark of the cardiorenal syndrome is intense sodium avidity and diuretic resistance, often requiring a combination of diuretics with varying pharmacological targets, and monitoring of urinary response to guide escalations in therapy. Invasive means of decongestion may be required including ultrafiltration or KRT such as peritoneal dialysis, which is often better tolerated from a hemodynamic perspective than intermittent hemodialysis. Strategies for increasing forward perfusion in states of low cardiac output and cardiogenic shock may include afterload reduction and inotropes and, in the most severe cases, mechanical circulatory support devices, many of which have kidney-specific considerations.

A NOVEL RAT MODEL OF CONTRAST-INDUCED ACUTE KIDNEY INJURY BASED ON RENAL CONGESTION AND THE RENO-PROTECTION OF MITOCHONDRIAL FISSION INHIBITION

ABSTRACT

Contrast-induced acute kidney injury (CI-AKI) is a serious and common complication in patients receiving intravenous iodinated contrast medium (CM). Clinically, congestive heart failure is the most critical risk factor for CI-AKI and always leads to renal congestion for increased central venous pressure and fluid overload. Here, we aimed to investigate a novel CI-AKI rat model based on renal congestion. After the exploratory testing phase, we successfully constructed a CI-AKI rat model by inducing renal congestion by clamping the unilateral renal vein, removing the contralateral kidney, and a single tail vein injection of iohexol. This novel CI-AKI rat model showed elevated serum creatinine, urea nitrogen, and released tubular injury biomarkers (KIM-1 and NGAL), reduced glomerular filtration rate, and typical pathologic features of CM-induced tubular injury with extensive foamy degeneration, tubular edema, and necrosis. Electron microscopy and confocal laser scanning revealed excessive mitochondrial fission and increased translocation of Drp1 from the cytoplasm to the mitochondrial surface in tubular epithelial cells. As a Drp1 inhibitor, Mdivi-1 attenuated excessive mitochondrial fission and exerted reno-protection against CM injury. Simultaneously, Mdivi-1 alleviated oxidative stress, apoptosis, and inflammatory responses induced by CM toxicity. We concluded that renal congestion exacerbated CM toxicity and presented a novel CI-AKI rat model. Excessive mitochondrial fission plays a crucial role in CM reno-toxicity and is a promising target for preventing and treating CI-AKI.

Edema formation in congestive heart failure and the underlying mechanisms

Congestive heart failure (HF) is a complex disease state characterized by impaired ventricular function and insufficient peripheral blood supply. The resultant reduced blood flow characterizing HF promotes activation of neurohormonal systems which leads to fluid retention, often exhibited as pulmonary congestion, peripheral edema, dyspnea, and fatigue. Despite intensive research, the exact mechanisms underlying edema formation in HF are poorly characterized. However, the unique relationship between the heart and the kidneys plays a central role in this phenomenon. Specifically, the interplay between the heart and the kidneys in HF involves multiple interdependent mechanisms, including hemodynamic alterations resulting in insufficient peripheral and renal perfusion which can lead to renal tubule hypoxia. Furthermore, HF is characterized by activation of neurohormonal factors including renin-angiotensin-aldosterone system (RAAS), sympathetic nervous system (SNS), endothelin-1 (ET-1), and anti-diuretic hormone (ADH) due to reduced cardiac output (CO) and renal perfusion. Persistent activation of these systems results in deleterious effects on both the kidneys and the heart, including sodium and water retention, vasoconstriction, increased central venous pressure (CVP), which is associated with renal venous hypertension/congestion along with increased intra-abdominal pressure (IAP). The latter was shown to reduce renal blood flow (RBF), leading to a decline in the glomerular filtration rate (GFR). Besides the activation of the above-mentioned vasoconstrictor/anti-natriuretic neurohormonal systems, HF is associated with exceptionally elevated levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). However, the supremacy of the deleterious neurohormonal systems over the beneficial natriuretic peptides (NP) in HF is evident by persistent sodium and water retention and cardiac remodeling. Many mechanisms have been suggested to explain this phenomenon which seems to be multifactorial and play a major role in the development of renal hyporesponsiveness to NPs and cardiac remodeling. This review focuses on the mechanisms underlying the development of edema in HF with reduced ejection fraction and refers to the therapeutic maneuvers applied today to overcome abnormal salt/water balance characterizing HF.

Crosstalk between gut microbiota and renal ischemia/reperfusion injury

Renal ischemia-reperfusion injury (IRI) is the main cause of acute kidney injury and the cause of rapid renal dysfunction and high mortality. In recent years, with the gradual deepening of the understanding of the intestinal flora, exploring renal IRI from the perspective of the intestinal flora has become a research hotspot. It is well known that the intestinal flora plays an important role in maintaining human health, and dysbiosis is the change in the composition and function of the intestinal tract, which in turn causes intestinal barrier dysfunction. Studies have shown that there are significant differences in the composition of intestinal flora before and after renal IRI, and this difference is closely related to the occurrence and development of renal IRI and affects prognosis. In addition, toxins produced by dysregulated gut microbes enter the bloodstream, which in turn exacerbates kidney damage. This article reviews the research progress of intestinal flora and renal IRI, in order to provide new treatment ideas and strategies for renal IRI.

What We Have Learned so far From Single Cell Sequencing in Acute Kidney Injury

Acute Kidney injury is a major clinical problem associated with increased morbidity and mortality. Despite, intensive research the clinical outcome remains poor and apart from supportive therapy no other specific therapy exists. Single cell technologies have enabled us to get deeper insights into the transcriptome of individual cells in complex tissues like the kidney. With respect to kidney injury, this would allow us to better define the unique role of individual cell populations in the pathophysiology of acute kidney injury and progression to chronic kidney disease. In this mini review, we would like to give an overview and discuss the current major findings in the field of acute kidney injury through Single-Cell technologies.