MicroRNA-874-3p/ADAM (A Disintegrin and Metalloprotease) 19 Mediates Macrophage Activation and Renal Fibrosis After Acute Kidney Injury

SNORD3A Regulates STING Transcription to Promote Ferroptosis in Acute Kidney Injury

Acute kidney injury (AKI) signifies a sudden and prolonged decline in kidney function characterized by tubular cell death and interstitial inflammation. Small nucleolar RNAs (snoRNAs) play pivotal roles in oxidative stress and inflammation, and may play an important role in the AKI process, which remains elusive. an elevated expression of Snord3a is revealed in renal tubules in response to AKI and demonstrates that Snord3a deficiency alleviates renal injury in AKI mouse models. Notably, the deficiency of Snord3a exhibits a mitigating effect on the stimulator of interferon genes (STING)-associated ferroptosis phenotypes and the progression of tubular injury. Mechanistically, Snord3a is shown to regulate the STING signaling axis via promoting STING gene transcription; administration of Snord3a antisense oligonucleotides establishes a significant therapeutic advantage in AKI mouse models. Together, the findings elucidate the transcription regulation mechanism of STING and the crucial roles of the Snord3a-STING axis in ferroptosis during AKI, underscoring Snord3a as a potential prognostic and therapeutic target for AKI.

Role of renal tubular epithelial cells and macrophages in cisplatin-induced acute renal injury

Acute kidney injury (AKI) is a clinical syndrome characterized by a sudden and continuous decline in renal function. The drug cisplatin is commonly used as chemotherapy for solid tumors, and cisplatin-induced acute kidney injury (CI-AKI), which is characterized by acute tubular necrosis and inflammation, frequently occurs in tumor patients. Renal tubular epithelial cells (RTECs) are severely damaged early in this process and play an important role in renal tubular injury and the recruitment of immune cells. Macrophages are the most common infiltrating immune cells in the kidney and have a significant impact on CI-AKI and subsequent repair. This article reviews the latest research progress on the effects of RTECs and macrophages on CI-AKI and their interactions in AKI to provide a direction for identifying therapeutic targets for treating AKI.

miR-146b-5p downregulates IRAK1 and ADAM19 to suppress trophoblast proliferation, invasion, and migration in miscarriage†

A large proportion of miscarriages are classified as unexplained miscarriages since no cause is identified. No reliable biomarkers or treatments are available for these pregnancy losses. While our transcriptomic sequencing has revealed substantial upregulation of miR-146b-5p in unexplained miscarriage villous tissues, its role and associated molecular processes have yet to be fully characterized. Our work revealed that relative to samples from normal pregnancy, miR-146b-5p was significantly elevated in villous tissues from unexplained miscarriage patients and displayed promising diagnostic potential. Moreover, miR-146b-5p agomir contributed to higher rates of embryonic resorption in ICR mice. When overexpressed in HTR-8/SVneo cells, miR-146b-5p attenuated the proliferative, invasive, and migratory activity of these cells while suppressing the expression of MMP9 and immune inflammation-associated cytokines, including IL1B, IL11, CXCL1, CXCL8, and CXCL12. Conversely, inhibition of its expression enhanced proliferation, migration, and invasion abilities. Mechanistically, IL-1 receptor-associated kinase-1 and a disintegrin and metalloproteinase 19 were identified as miR-146b-5p targets regulating trophoblast function, and silencing IL-1 receptor-associated kinase-1 had similar effects as miR-146b-5p overexpression, while IL-1 receptor-associated kinase-1 overexpression could partially reverse the inhibitory impact of this microRNA on trophoblasts. miR-146b-5p may inhibit trophoblast proliferation, migration, invasion, and implantation-associated inflammation by downregulating IL-1 receptor-associated kinase-1 and a disintegrin and metalloproteinase 19, participating in the pathogenesis of miscarriage and providing a critical biomarker and a promising therapeutic target for unexplained miscarriage.

Relationship between ferroptosis and mitophagy in renal fibrosis: a systematic review

Renal fibrosis, characterised by glomerulosclerosis and tubulointerstitial fibrosis, is a typical pathological alteration in the progression of chronic kidney disease (CKD) to end-stage renal disease (ESRD). However, the limited and expensive options for treating renal fibrosis place a heavy financial burden on patients and healthcare systems. Therefore, it is significant to find an effective treatment for renal fibrosis. Ferroptosis, a non-traditional form of cell death, has been found to play an important role in acute kidney injury (AKI), tumours, neurodegenerative diseases, and so on. Moreover, a growing body of research suggests that ferroptosis might be a potential target of renal fibrosis. Meanwhile, mitophagy is a type of selective autophagy that can selectively degrade damaged or dysfunctional mitochondria as a form of mitochondrial quality control, reducing the production of reactive oxygen species (ROS), the accumulation of which is the main cause of renal fibrosis. Additionally, as a receptor of mitophagy, NIX can release beclin1 to induce mitophagy, which can also bind to solute carrier family 7 member 11 (SLC7A11) to block the activity of cystine/glutamate antitransporter (system Xc-) and inhibit ferroptosis, thereby suggesting a link between mitophagy and ferroptosis. However, there have been only limited studies on the relationship among mitophagy, ferroptosis and renal fibrosis. In this paper, we review the mechanisms of mitophagy, and describe how ferroptosis and mitophagy are related to renal fibrosis in an effort to identify potential novel targets for the treatment of renal fibrosis.

Serum IL-12p40: A novel biomarker for early prediction of minimal change disease relapse following glucocorticoids therapy

Background

Minimal change disease (MCD) has a high recurrence rate, but currently, no biomarker can predict its recurrence. To this end, this study aimed at identifying potential serum cytokines as valuable biomarkers for predicting the risk of MCD recurrence.

Materials and methods

Raybiotech 440 cytokine antibody microarray was used to detect the serum samples of eight relapsed, eight non-relapsed MCD patients after glucocorticoid treatment, and eight healthy controls. The differentially expressed cytokines were confirmed by enzyme-linked immunosorbent assay (ELISA) with serum samples from 29 non-relapsed and 35 relapsed MCD patients. The study used the receiver operating characteristic (ROC) curve analysis to investigate the sensitivity and specificity of a serum biomarker for predicting the MCD relapse.

Results

Serum IL-12p40 levels increased significantly in the relapsed group. The Area Under the ROC Curve (AUC) of IL-12p40 was 0.727 (95%CI: 0.597-0.856; P < 0.01). The RNA-sequencing analysis and qPCR assay performed on the IL-12 treated mouse podocytes and the control group showed increased expression of podocyte damage genes, such as connective tissue growth factor (CTGF), matrix metallopeptidase 9 (MMP9), secreted phosphoprotein 1 (SPP1), and cyclooxygenase-2 (COX-2) in the former group.

Conclusion

IL-12p40 may serve as a new biomarker for predicting the risk of MCD recurrence after glucocorticoid treatment, and it may be involved in the pathogenesis and recurrence of MCD.

A circular RNA, circPTPN14, increases MYC transcription by interacting with FUBP1 and exacerbates renal fibrosis

Fibrosis is a relentlessly progressive and irreversible cause of organ damage, as in chronic kidney disease (CKD), but its underlying mechanisms remain elusive. We found that a circular RNA, circPTPN14, is highly expressed in human kidneys with biopsy-proved chronic interstitial fibrosis, mouse kidneys subjected to ischemia/reperfusion (IR) or unilateral ureteral obstruction (UUO), and TGFβ1-stimulated renal tubule epithelial cells (TECs). The intrarenal injection of circPTPN14 shRNA alleviated the progression of fibrosis in kidneys subjected to IR or UUO. Knockdown of circPTPN14 in TECs inhibited TGFβ1-induced expression of profibrotic genes, whereas overexpressing circPTPN14 increased the profibrotic effect of TGFβ1. The profibrotic action of circPTPN14 was ascribed to an increase in MYC transcription. The binding of circPTPN14 to the KH3 and KH4 domains of far upstream element (FUSE) binding protein 1 (FUBP1) enhanced the interaction between FUBP1 and FUSE domain, which was required for the initiation of MYC transcription. In human kidneys (n = 30) with biopsy-proved chronic interstitial fibrosis, the expression of circPTPN14 positively correlated with MYC expression. Taken together these studies show a novel mechanism in the pathogenesis of renal fibrosis, mediated by circPTPN14, which can be a target in the diagnosis and treatment of CKD.

Faecalibacterium prausnitzii Attenuates CKD via Butyrate-Renal GPR43 Axis

BACKGROUND

Despite available clinical management strategies, chronic kidney disease (CKD) is associated with severe morbidity and mortality worldwide, which beckons new solutions. Host-microbial interactions with a depletion of Faecalibacterium prausnitzii in CKD are reported. However, the mechanisms about if and how F prausnitzii can be used as a probiotic to treat CKD remains unknown.

METHODS

We evaluated the microbial compositions in 2 independent CKD populations for any potential probiotic. Next, we investigated if supplementation of such probiotic in a mouse CKD model can restore gut-renal homeostasis as monitored by its effects on suppression on renal inflammation, improvement in gut permeability and renal function. Last, we investigated the molecular mechanisms underlying the probiotic-induced beneficial outcomes.

RESULTS

We observed significant depletion of Faecalibacterium in the patients with CKD in both Western (n=283) and Eastern populations (n=75). Supplementation of F prausnitzii to CKD mice reduced renal dysfunction, renal inflammation, and lowered the serum levels of various uremic toxins. These are coupled with improved gut microbial ecology and intestinal integrity. Moreover, we demonstrated that the beneficial effects in kidney induced by F prausnitzii-derived butyrate were through the GPR (G protein-coupled receptor)-43.

CONCLUSIONS

Using a mouse CKD model, we uncovered a novel beneficial role of F prausnitzii in the restoration of renal function in CKD, which is, at least in part, attributed to the butyrate-mediated GPR-43 signaling in the kidney. Our study provides the necessary foundation to harness the therapeutic potential of F prausnitzii for ameliorating CKD.

Mitophagy induced by UMI-77 preserves mitochondrial fitness in renal tubular epithelial cells and alleviates renal fibrosis

Renal fibrosis is the final common outcome of chronic kidney disease (CKD), which remains a huge challenge due to a lack of targeted treatment. Growing evidence suggests that during the process of CKD, the integrity and function of mitochondria in renal tubular epithelial cells (TECs) are generally impaired and strongly connected with the progression of renal fibrosis. Mitophagy, a selective form of autophagy, could remove aberrant mitochondria to maintain mitochondrial homeostasis. Deficiency of mitophagy has been reported to aggravate renal fibrosis. However, whether induction of mitophagy could alleviate renal fibrosis has not been stated. In this study, we explored the effect of mitophagy activation by UMI-77, a compound recently verified to induce mitophagy, on murine CKD model of unilateral ureteral obstruction (UUO) in vivo and TECs in vitro. In UUO mice, we found the changes of mitochondrial damage, ROS production, transforming growth factor (TGF)-β1/Smad pathway activation, as well as epithelial-mesenchymal transition phenotype and renal fibrosis, and these changes were ameliorated by mitophagy enhancement using UMI-77. Moreover, TEC apoptosis, nuclear factor (NF)-κB signaling activation, and interstitial inflammation after UUO were significantly mitigated by augmented mitophagy. Then, we found UMI-77 could effectively and safely induce mitophagy in TECs in vitro, and reduced TGF-β1/Smad signaling and downstream profibrotic responses in TGF-β1-treated TECs. These changes were restored by a mitophagy inhibitor. In conclusion, we demonstrated that mitophagy activation protected against renal fibrosis through improving mitochondrial fitness, downregulating TGF-β1/Smad signaling and alleviating TEC injuries and inflammatory infiltration in kidneys.

ADAMs family in kidney physiology and pathology

A disintegrin and metalloproteinases (ADAMs) family are proteolytic transmembrane proteases that modulate diverse cell functions and coordinate intercellular communication. ADAMs are responsible for regulating cell proliferation, differentiation, migration, and organ morphogenesis in kidney development. Abnormally activated ADAMs drive inflammation and fibrosis in response to kidney diseases such as acute kidney injury, diabetic kidney disease, polycystic kidney disease, and chronic allograft nephropathy. ADAM10 and ADAM17, known as the most characterized members of ADAMs, are extensively investigated in kidney diseases. Notably, ADAM proteases have the potential to be targets for developing novel treatment approaches in kidney diseases.

DNA demethylase Tet2 suppresses cisplatin-induced acute kidney injury

Demethylase Tet2 plays a vital role in the immune response. Acute kidney injury (AKI) initiation and maintenance phases are marked by inflammatory responses and leukocyte recruitment in endothelial and tubular cell injury processes. However, the role of Tet2 in AKI is poorly defined. Our study determined the degree of renal tissue damage associated with Tet2 gene expression levels in a cisplatin-induced AKI mice model. Tet2-knockout (KO) mice with cisplatin treatment experienced severe tubular necrosis and dilatation, inflammation, and AKI markers' expression levels than the wild-type mice. In addition, the administration of Tet2 plasmid protected Tet2-KO mice from cisplatin-induced nephrotoxicity, but not Tet2-catalytic-dead mutant. Tet2 KO was associated with a change in metabolic pathways like retinol, arachidonic acid, linolenic acid metabolism, and PPAR signaling pathway in the cisplatin-induced mice model. Tet2 expression is also downregulated in other AKI mice models and clinical samples. Thus, our results indicate that Tet2 has a renal protective effect during AKI by regulating metabolic and inflammatory responses through the PPAR signaling pathway.