KIM-1-mediated anti-inflammatory activity is preserved by MUC1 induction in the proximal tubule during ischemia-reperfusion injury

Dexmedetomidine mitigates acute kidney injury after coronary artery bypass grafting: a prospective clinical trial

INTRODUCTION AND OBJECTIVES

To evaluate the impact of dexmedetomidine impact on cardiac surgery-associated acute kidney injury (CSA-AKI), kidney function, and metabolic and oxidative stress in patients undergoing coronary artery bypass grafting with heart-lung machine support.

METHODS

A randomized double-masked trial with 238 participants (50-75 years) undergoing coronary artery bypass grafting was conducted from January 2021 to December 2022. The participants were divided into Dex (n=119) and NS (n = 119) groups. Dex was administered at 0.5 mcg/kg over 10minutes, then 0.4 mcg/kg/h until the end of surgery; the NS group received equivalent saline. Blood and urine were sampled at various time points pre- and postsurgery. The primary outcome measure was the incidence of CSA-AKI, defined as the occurrence of AKI within 96hours after surgery.

RESULTS

The incidence of CSA-AKI was significantly lower in the Dex group than in the NS group (18.26% vs 32.46%; P=.014). Substantial increases were found in estimated glomerular filtration rate value at T4-T6 (P<.05) and urine volume 24hours after surgery (P<.01). Marked decreases were found in serum creatinine level, blood glucose level at T1-T2 (P<.01), blood urea nitrogen level at T3-T6 (P<.01), free fatty acid level at T2-T3 (P<.01), and lactate level at T3-T4 (P<.01).

CONCLUSIONS

Dex reduces CSA-AKI, potentially by regulating metabolic disorders and reducing oxidative stress. Registered with the Chinese Clinical Study Registry (No. ChiCTR2100051804).

Unraveling Chronic Cardiovascular and Kidney Disorder through the Butterfly Effect

Chronic Cardiovascular and Kidney Disorder (CCKD) represents a growing challenge in healthcare, characterized by the complex interplay between heart and kidney diseases. This manuscript delves into the "butterfly effect" in CCKD, a phenomenon in which acute injuries in one organ lead to progressive dysfunction in the other. Through extensive review, we explore the pathophysiology underlying this effect, emphasizing the roles of acute kidney injury (AKI) and heart failure (HF) in exacerbating each other. We highlight emerging therapies, such as renin-angiotensin-aldosterone system (RAAS) inhibitors, SGLT2 inhibitors, and GLP1 agonists, that show promise in mitigating the progression of CCKD. Additionally, we discuss novel therapeutic targets, including Galectin-3 inhibition and IL33/ST2 pathway modulation, and their potential in altering the course of CCKD. Our comprehensive analysis underscores the importance of recognizing and treating the intertwined nature of cardiac and renal dysfunctions, paving the way for more effective management strategies for this multifaceted syndrome.

The effects of apoptosis inhibitor of macrophage in kidney diseases

Kidney disease is a progressive and irreversible condition in which immunity is a contributing factor that endangers human health. It is widely acknowledged that macrophages play a significant role in developing and causing numerous kidney diseases. The increasing focus on the mechanism by which macrophages express apoptosis inhibitor of macrophages (AIM) in renal diseases has been observed. AIM is an apoptosis inhibitor that stops different things that cause apoptosis from working. This keeps AIM-bound cell types alive. Notably, the maintenance of immune cell viability regulates immunity. As our investigation progressed, we concluded that AIM has two sides when it comes to renal diseases. AIM can modulate renal phagocytosis, expedite the elimination of renal tubular cell fragments, and mitigate tissue injury. AIM can additionally exacerbate the development of renal fibrosis and kidney disease by prolonging inflammation. IgA nephropathy (IgAN) may also worsen faster if more protein is in the urine. This is because IgA and immunoglobulin M are found together and expressed. In the review, we provide a comprehensive overview of prior research and concentrate on the impacts of AIM on diverse subcategories of nephropathies. We discovered that AIM is closely associated with renal diseases by playing a positive or negative role in the onset, progression, or cure of kidney disease. AIM is thus a potentially effective therapeutic target for kidney diseases.

Ramelteon attenuates renal ischemia and reperfusion injury through reducing mitochondrial fission and fusion and inflammation

Background

Renal ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury (AKI). This study explored the function and mechanisms of ramelteon on IRI-induced AKI.

Methods

Mice were randomly divided into five groups: Sham, IRI, IRI + ramelteon (0.3 mg/kg), IRI + ramelteon (1 mg/kg), and IRI + ramelteon (3 mg/kg). Mice were intraperitoneally treated with ramelteon for 7 days before IRI. IRI was accomplished by bilateral renal artery clamping for 30 minutes, after which the clamps were removed for blood reperfusion. HK-2 cells were randomly divided into five groups: control, hypoxia/reoxygenation (H/R), H/R + ramelteon (10 nM), H/R + ramelteon (30 nM), and H/R + ramelteon (60 nM). HK-2 cells were prophylactically treated with ramelteon and then exposed to H/R.

Results

Ramelteon attenuated renal injury, inhibited cell apoptosis, decreased reactive oxygen species (ROS) generation, and suppressed levels of interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β). Ramelteon decreased apoptosis-related protein Bax and TLR4-related proteins (TLR4, MyD88, p-IκBα, and p-p65 NF-κB), enhanced apoptosis-related protein Bcl-2. Furthermore, ramelteon increased mitochondrial membrane potential in H/R cells. Mitochondrial-related proteins (Drp1, Fis1, and Mff) were abated, whereas Mfn1 and Mfn2 were enhanced in H/R induced cells.

Conclusions

Ramelteon attenuates renal injury induced by IRI and H/R, which is involved in apoptosis, mitochondrial damage, and inflammation.

Hypoxia controls expression of kidney-pathogenic MUC1 variants

The interplay between genetic and environmental factors influences the course of chronic kidney disease (CKD). In this context, genetic alterations in the kidney disease gene MUC1 (Mucin1) predispose to the development of CKD. These variations comprise the polymorphism rs4072037, which alters splicing of MUC1 mRNA, the length of a region with variable number of tandem repeats (VNTR), and rare autosomal-dominant inherited dominant-negative mutations in or 5' to the VNTR that causes autosomal dominant tubulointerstitial kidney disease (ADTKD-MUC1). As hypoxia plays a pivotal role in states of acute and chronic kidney injury, we explored the effects of hypoxia-inducible transcription factors (HIF) on the expression of MUC1 and its pathogenic variants in isolated primary human renal tubular cells. We defined a HIF-binding DNA regulatory element in the promoter-proximal region of MUC1 from which hypoxia or treatment with HIF stabilizers, which were recently approved for an anti-anemic therapy in CKD patients, increased levels of wild-type MUC1 and the disease-associated variants. Thus, application of these compounds might exert unfavorable effects in patients carrying MUC1 risk variants.

Co-administration of angiotensin II and simvastatin triggers kidney injury upon heme oxygenase-1 deficiency

Kidneys are pivotal organ in iron redistribution and can be severely damaged in the course of hemolysis. In our previous studies, we observed that induction of hypertension with angiotensin II (Ang II) combined with simvastatin administration results in a high mortality rate or the appearance of signs of kidney failure in heme oxygenase-1 knockout (HO-1 KO) mice. Here, we aimed to address the mechanisms underlying this effect, focusing on heme and iron metabolism. We show that HO-1 deficiency leads to iron accumulation in the renal cortex. Higher mortality of Ang II and simvastatin-treated HO-1 KO mice coincides with increased iron accumulation and the upregulation of mucin-1 in the proximal convoluted tubules. In vitro studies showed that mucin-1 hampers heme- and iron-related oxidative stress through the sialic acid residues. In parallel, knock-down of HO-1 induces the glutathione pathway in an NRF2-depedent manner, which likely protects against heme-induced toxicity. To sum up, we showed that heme degradation during heme overload is not solely dependent on HO-1 enzymatic activity, but can be modulated by the glutathione pathway. We also identified mucin-1 as a novel redox regulator. The results suggest that hypertensive patients with less active HMOX1 alleles may be at higher risk of kidney injury after statin treatment.

Emergence of MUC1 in Mammals for Adaptation of Barrier Epithelia

The mucin 1 (MUC1) gene was discovered based on its overexpression in human breast cancers. Subsequent work demonstrated that MUC1 is aberrantly expressed in cancers originating from other diverse organs, including skin and immune cells. These findings supported a role for MUC1 in the adaptation of barrier tissues to infection and environmental stress. Of fundamental importance for this evolutionary adaptation was inclusion of a SEA domain, which catalyzes autoproteolysis of the MUC1 protein and formation of a non-covalent heterodimeric complex. The resulting MUC1 heterodimer is poised at the apical cell membrane to respond to loss of homeostasis. Disruption of the complex releases the MUC1 N-terminal (MUC1-N) subunit into a protective mucous gel. Conversely, the transmembrane C-terminal (MUC1-C) subunit activates a program of lineage plasticity, epigenetic reprogramming and repair. This MUC1-C-activated program apparently evolved for barrier tissues to mount self-regulating proliferative, inflammatory and remodeling responses associated with wound healing. Emerging evidence indicates that MUC1-C underpins inflammatory adaptation of tissue stem cells and immune cells in the barrier niche. This review focuses on how prolonged activation of MUC1-C by chronic inflammation in these niches promotes the cancer stem cell (CSC) state by establishing auto-inductive nodes that drive self-renewal and tumorigenicity.

Heat acclimation ameliorated heat stress-induced acute kidney injury and prevented changes in kidney macrophages and fibrosis

Heatstroke can cause acute kidney injury (AKI), which reportedly progresses to chronic kidney disease. Kidney macrophages may be involved in such injury. Although heat acclimation (HA) provides thermal resilience, its renoprotective effect and mechanism remain unclear. To investigate heat stress-induced kidney injuries in mice and the mitigating effect of HA on them, male C57/BL6J mice were exposed to heat stress (40℃, 1 h), with or without 5-day HA (38℃, 3 h/day) prior to heat stress. Heat stress damaged kidney proximal tubules with elevation of urinary kidney injury molecule-1 (KIM-1). Kidney fibrosis was observed on day 7 and correlated with the urinary KIM-1 levels on day 3. Kidney resident macrophages decreased on day 1, whereas the number of infiltrating macrophages in the kidney did not change. Both subsets of macrophages polarized to the pro-inflammatory M1 phenotype on day 1; however, they polarized to the anti-inflammatory M2 phenotype on day 7. HA significantly ameliorated heat stress-induced proximal tubular damage and kidney fibrosis. HA substantially increased heat shock protein 70 (Hsp70) expression in the tubules before heat stress and reduced an elevation of cleaved caspase-3 expression after heat stress. HA also induced the Hsp70 expression of resident macrophages and prevented heat stress-induced changes in both subsets of kidney macrophages. These results provide pathophysiological data supporting the renoprotective effect of HA. Further studies are needed to confirm that HA can prevent kidney damage due to heat stress in humans.

Using Imaging Mass Cytometry to Define Cell Identities and Interactions in Human Tissues

In the evolving landscape of highly multiplexed imaging techniques that can be applied to study complex cellular microenvironments, this review characterizes the use of imaging mass cytometry (IMC) to study the human kidney. We provide technical details for antibody validation, cell segmentation, and data analysis specifically tailored to human kidney samples, and elaborate on phenotyping of kidney cell types and novel insights that IMC can provide regarding pathophysiological processes in the injured or diseased kidney. This review will provide the reader with the necessary background to understand both the power and the limitations of IMC and thus support better perception of how IMC analysis can improve our understanding of human disease pathogenesis and can be integrated with other technologies such as single cell sequencing and proteomics to provide spatial context to cellular data.