TSC1 Affects the Process of Renal Ischemia-Reperfusion Injury by Controlling Macrophage Polarization

MiR-21 suppression in macrophages promotes M2-like polarization and attenuates kidney ischemia-reperfusion injury

MicroRNA-21 (miR-21) is one of the most frequently upregulated miRNAs in response to kidney ischemia-reperfusion (IR) injury, exhibiting both protective and pathogenic effects depending on the cell type, disease state, and target signaling. In this study, we analyzed the function of miR-21 in various cell types to elucidate its role in ischemia-induced inflammation and acute kidney injury (AKI). Utilizing a mouse model of IR injury, we observed significant upregulation of miR-21 in renal tubular epithelial cells and macrophages following IR. Deletion of miR-21 in macrophages mitigated IR-induced pro-inflammatory cytokine production and AKI. However, conditional deletion of miR-21 in proximal tubules or nonproximal tubules did not protect the kidneys against these effects. Mechanistically, miR-21 inhibition promoted M2-like polarization in macrophages and suppressed M1-like polarization and proinflammatory cytokine production in kidneys. In vitro, miR-21 knockdown in the mouse macrophage cell line Raw246.7 or genetic deletion of miR-21 in bone marrow-derived macrophages (BMDMs) increased the percentage of CD206+ cells (M2 phenotype) while decreasing the percentage of CD86+ cells (M1 phenotype) and the expressions of proinflammatory cytokines. Overexpression of miR-21 in Raw264.7 cells reduced the percentage of CD206+ cells. Furthermore, we demonstrated that signal transducer and activator of transcription 3 (STAT3) was a target gene of miR-21 in macrophages, and miR-21 deletion promoted M2 macrophage polarization via STAT3 activation. In conclusion, miR-21 plays a role in regulating macrophage polarization, and the blockade of miR-21/STAT3 signaling may represent a novel therapeutic strategy for the prevention or treatment of AKI.

Comprehensive Analysis of RNA Methylation-Regulated Gene Signature and Immune Infiltration in Ischemia/Reperfusion-Induced Acute Kidney Injury

INTRODUCTION

The morbidity and mortality of acute kidney injury (AKI) are increasing. Epigenetic regulation and immune cell infiltration are thought to be involved in AKI. However, the relationship between epigenetic regulation and immune cell infiltration in AKI has not been elucidated. This study was conducted to identify the differentially expressed genes (DEGs), differentially expressed RNA methylation genes (DEMGs), and infiltrated immune cells in the kidneys of ischemia-reperfusion induced-acute kidney injury (IRI-AKI) models and further explore their relationships in IRI-AKI.

METHODS

This is a bioinformatic analysis using R programming language in 3 selected IRI-AKI datasets from the Gene Expression Omnibus (GEO) database, including 16 IRI-AKI kidney tissues and 10 normal kidney tissues. The DEGs were screened, and enrichment pathways were analyzed using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The DEMGs and core DEMGs were identified using the R package. The ROC curve was plotted to predict disease occurrence of 7 core DEMGs. The correlation of 7 core DEMGs and other genes was analyzed using Pearson's correlation test. The gene set enrichment analysis (GSEA) of each DEMG was conducted using the R package. The upstream miRNAs and transcript factors of 7 core DEMGs were predicted based on the RegNetwork database and Cytoscape software. The STITCH database was used to predict the possible binding compounds of the 7 core DEMGs. Immune cell infiltration in kidney tissues between the IRI-AKI group and control group was evaluated using the R package.

RESULTS

A total of 2,367 DEGs were obtained, including 1,180 upregulated and 1,187 downregulated genes in IRI-AKI kidney associated with the cell structure, proliferation, molecule binding/interaction, and signaling pathways such as the leukocyte migration and chemokine signaling pathways. Ten DEMGs were identified, with Ythdf1, Rbm15, Trmt6, Hnrnpc, and Dnmt1 being significantly upregulated, while Lrpprc, Cyfip2, Mettl3, Ncbp2, and Nudt7 were significantly downregulated in IRI-AKI tissues. The molecules interacting with 7 core DEMGs were identified. Significant changes in the infiltration of 8 types of immune cells were observed in IRI-AKI kidneys compared to normal controls. The significant correlation between 6 core DEMGs and the infiltration of immune cells was observed.

CONCLUSION

IRI may induce AKI through RNA methylation to regulate the expression of genes involved in immune cell infiltration.

Exosomes on the development and progression of renal fibrosis

Renal fibrosis is a prevalent pathological alteration that occurs throughout the progression of primary and secondary renal disorders towards end-stage renal disease. As a complex and irreversible pathophysiological phenomenon, it includes a sequence of intricate regulatory processes at the molecular and cellular levels. Exosomes are a distinct category of extracellular vesicles that play a crucial role in facilitating intercellular communication. Multiple pathways are regulated by exosomes produced by various cell types, including tubular epithelial cells and mesenchymal stem cells, in the context of renal fibrosis. Furthermore, research has shown that exosomes present in bodily fluids, including urine and blood, may be indicators of renal fibrosis. However, the regulatory mechanism of exosomes in renal fibrosis has not been fully elucidated. This article reviewed and analysed the various mechanisms by which exosomes regulate renal fibrosis, which may provide new ideas for further study of the pathophysiological process of renal fibrosis and targeted treatment of renal fibrosis with exosomes.

Targeting Macrophages in Organ Transplantation: A Step Toward Personalized Medicine

Organ transplantation remains the most optimal strategy for patients with end-stage organ failure. However, prevailing methods of immunosuppression are marred by adverse side effects, and allograft rejection remains common. It is imperative to identify and comprehensively characterize the cell types involved in allograft rejection, and develop therapies with greater specificity. There is increasing recognition that processes mediating allograft rejection are the result of interactions between innate and adaptive immune cells. Macrophages are heterogeneous innate immune cells with diverse functions that contribute to ischemia-reperfusion injury, acute rejection, and chronic rejection. Macrophages are inflammatory cells capable of innate allorecognition that strengthen their responses to secondary exposures over time via "trained immunity." However, macrophages also adopt immunoregulatory phenotypes and may promote allograft tolerance. In this review, we discuss the roles of macrophages in rejection and tolerance, and detail how macrophage plasticity and polarization influence transplantation outcomes. A comprehensive understanding of macrophages in transplant will guide future personalized approaches to therapies aimed at facilitating tolerance or mitigating the rejection process.

Transcriptomics-based exploration of shared M1-type macrophage-related biomarker in acute kidney injury after kidney transplantation and acute rejection after kidney transplantation

BACKGROUND

Macrophage type 1 (M1) cells are associated with both acute kidney injury (AKI) during kidney transplantation and acute rejection (AR) after kidney transplantation. Our study explored M1-related biomarkers involved in both AKI and AR and their potential biological functions.

METHODS

Based on the Gene Expression Omnibus (GEO) database, the immune cell infiltration levels and differentially expressed genes were examined in AKI and AR in the kidney transplantation; M1-related genes shared in AKI and AR were identified using weighted gene co-expression analysis (WGCNA) system. Subsequently, protein-protein interaction (PPI) networks and machine learning methods to identify Hub genes and construct diagnostic models. Both AKI model and AR rat models were built to validate the expressions of Hub genes and test the injury phenotype, oxidative stress markers, and inflammatory factors. Finally, the transcription factor (TF)-Hub gene and micro-RNA (miRNA)-Hub gene regulatory networks were constructed based on identified Hub genes.

RESULTS

Out of 2167 differential expression genes (DEGs) in AKI and 2100 DEGs in AR, four M1-related Hub genes were obtained by PPI networks and machine learning methods, namely GBP2, TYROBP, CCR5, and TLR8. The calibration curves in the nomogram diagnostic model for these four Hub genes suggested the same predictive probability as an ideal model for AKI and AR after kidney transplantation (AUC values of the area under the ROC curve were all >0.7). The same observations were confirmed in ischemia reperfusion injury (IRI) and AR rat models by identifying common four Hub genes (GBP2, TYROBP, TLR8, and CCR5). Western blots showed that these four Hub genes were significantly different in rat models of IRI and AR (all p<0.05). Compared with the control group, IRI and AR groups showed aggravated histopathological damage and increased secretion of oxidative stress markers and inflammatory factors in rat kidneys (all p<0.05). Finally, TF-Hub and miRNA-Hub gene regulatory networks were constructed to provide a theoretical basis for the regulation of Hub genes.

CONCLUSION

We identified four macrophage M1-related Hub genes shared among AKI and AR after kidney transplantation. These genes may be considered for diagnosis of AKI and AR after kidney transplantation.

Macrophage polarization and signaling in diabetic kidney disease: a catalyst for disease progression

Diabetic kidney disease (DKD) is a serious complication of diabetes affecting millions of people worldwide. Macrophages, a critical immune cell type, are central players in the development and progression of DKD. In this comprehensive review, we delve into the intricate role of macrophages in DKD, examining how they can become polarized into proinflammatory M1 or anti-inflammatory M2 phenotypes. We explore the signaling pathways involved in macrophage recruitment and polarization in the kidneys, including the key cytokines and transcription factors that promote M1 and M2 polarization. In addition, we discuss the latest clinical studies investigating macrophages in DKD and explore the potential of hypoglycemic drugs for modulating macrophage polarization. By gaining a deeper understanding of the mechanisms that regulate macrophage polarization in DKD, we may identify novel therapeutic targets for this debilitating complication of diabetes. This review provides valuable insights into the complex interplay between macrophages and DKD, shedding light on the latest developments in this important area of research. This review aims to enhance understanding of the role that macrophages play in the pathogenesis of DKD.

Transcriptome-based exploration of potential molecular targets and mechanisms of selenomethionine in alleviating renal ischemia-reperfusion injury

Renal ischemia-reperfusion injuries (IRIs) are one of the leading causes of acute kidney injuries (AKIs). Selenium, as an essential trace element, is able to antioxidant stress and reduces inflammatory responses. The regulation mechanism of selenomethionine, one of the major forms of selenium intake by humans, is not yet clear in renal IRIs. Therefore, we aimed to explore the key targets and related mechanisms of selenomethionine regulation in renal IRIs and provide new ideas for the treatment of selenomethionine with renal IRIs. We used transcriptome sequencing data from public databases as well as animal experiments to explore the key target genes and related mechanisms regulated by selenomethionine in renal IRI. We found that selenomethionine can effectively alleviate renal IRI by a mechanism that may be achieved by inhibiting the MAPK signaling pathway. Meanwhile, we also found that the key target of selenomethionine regulation in renal IRI might be selenoprotein GPX3 based on the PPI protein interaction network and machine learning. Through a comprehensive analysis of bioinformatic techniques and animal experiments, we found that Gpx3 might serve as a key gene for the regulation of selenomethionine in renal IRIs. Selenomethionine may exert a protective effect against renal IRI by up-regulating GPX3, inhibiting the MAPK signaling pathway, increased production of antioxidants, decreasing inflammation levels, mitigation of apoptosis in renal tubular epithelial cells, this reduces renal histopathological damage and protects renal function. Providing a theoretical basis for the mechanism of selenomethionine actions in renal IRIs.

GOLPH3 promotes endotoxemia-induced liver and kidney injury through Golgi stress-mediated apoptosis and inflammatory response

Sepsis is a serious clinical condition characterized by a systemic inflammatory response, a leading cause of acute liver and kidney injury, and is associated with a high morbidity and mortality. Understanding the molecular mechanisms underlying the acute liver and kidney injury is crucial for developing an effective therapy. Golgi apparatus plays important roles and has various substrates mediating cellular stress responses. Golgi phosphoprotein 3 (GOLPH3), linking Golgi membranes to the cytoskeleton, has been identified as an important oncogenic regulator; however, its role in endotoxemia-induced acute liver and kidney injury remains elusive. Here, we found that upregulation of GOLPH3 was associated with endotoxemia-induced acute liver and kidney injury. Lipopolysaccharide (LPS) treatment increased Golgi stress and fragmentation, and associated pro-inflammatory mediator (Tnfα, IL-6, and IL-1β) production in vivo and in vitro. Interestingly, the downregulation of GOLPH3 significantly decreased LPS-induced Golgi stress and pro-inflammatory mediators (Tnfα, IL-6, Mcp1, and Nos2), and reversed apoptotic cell deaths in LPS-treated hepatocytes and renal tubular cells. GOLPH3 knockdown also reduced inflammatory response in LPS-treated macrophages. The AKT/NF-kB signaling pathway was suppressed in GOLPH3 knockdown, which may be associated with a reduction of inflammatory response and apoptosis and the recovery of Golgi morphology and function. Taken together, GOLPH3 plays a crucial role in the development and progression of acute liver and kidney injury by promoting Golgi stress and increasing inflammatory response and apoptosis, suggesting GOLPH3 as a potential therapeutic target for endotoxemia-induced tissue injury.

Research Progress of Cordyceps sinensis and Its Fermented Mycelium Products on Ameliorating Renal Fibrosis by Reducing Epithelial-to-Mesenchymal Transition

Renal fibrosis is a hallmark and common outcome of various chronic kidney diseases (CKDs) and manifests pathologically as accumulation and deposition of extracellular matrix (ECM) in the kidney. Epithelial-to-mesenchymal transition (EMT) has been shown to be an important mechanism involved in renal fibrosis. Cordyceps sinensis, a traditional Chinese medicine, has long been used for the treatment of renal fibrosis. As research on the mycelium of C. sinensis progressed, a variety of medicines developed from fermented mycelium were used to treat CKD. However, their efficacies and mechanisms have not been fully summarized. In this review, five medicines developed from fermented mycelium of C. sinensis are presented. The pharmacodynamic effects of C. sinensis on different animal models of renal fibrosis are summarized. The in vitro studies and related mechanisms of C. sinensis on renal cells are detailed. Finally, the application and efficacy of these five commercial medicines that meet national standards in different types of CKD are summarized. From this review, it can be concluded that C. sinensis can alleviate various causes of renal fibrosis to some extent, and its mechanism is related to TGF-β1 dependent signaling, inhibition of inflammation, and improvement of renal function. Further research on rigorously designed, large-sample, clinically randomized controlled trial studies and detailed mechanisms should be conducted.

Emodin Alleviates Lupus Nephritis in Rats by Regulating M1/M2 Macrophage Polarization

Lupus nephritis (LN) is one of the most common clinical manifestations of systemic lupus erythematosus (SLE), causing death and disability. The current research study explored whether there was any improvement effect on LN after emodin administration. Network pharmacology was used to screen the target genes of emodin for the treatment of LN. LPS and IL-4 were employed for RAW264.7 macrophage M1/M2 polarization induction, and 0.1% HgCl2 was used for the LN rat model’s establishment. Flow cytometry was performed to detect the effect of 20, 40, and 80 µM emodin on RAW264.7 macrophage polarization. HE and PAS staining were subsequently conducted to detect 70 mg/kg emodin action on renal injury in LN rats. The effect of emodin on the content of urinary proteins and dsDNA antibodies was also determined. The results indicated that peroxisome proliferators-activated receptors gamma (PPARG) may be a target gene of emodin in LN, and emodin had no significant toxicity to macrophages at different concentrations. Compared with the control, emodin significantly inhibited LPS-induced polarization in M1 macrophages and improved that of IL-4-induced M2 macrophages. Besides, emodin alleviated kidney injury and markedly reduced the levels of urinary protein and dsDNA antibodies in rats. Moreover, after targeting interference with the PPARG expression, the improvement effect of emodin on LN is significantly reduced, indicating that emodin may relieve the symptoms of LN by activating the PPARG expression. Our study revealed that PPARG may be applied as a new therapy for LN.

GPX3 and GSTT1 as biomarkers related to oxidative stress during renal ischemia reperfusion injuries and their relationship with immune infiltration

Background

Renal ischemia reperfusion injuries (IRIs) are very common in clinical diagnoses and treatments, which are a common cause of impaired renal functions, worsening pathological damage, affecting disease progression and hindering recovery. Renal IRIs are an inflammatory disease mediated by the adaptive and innate immune system. There is a complex interaction between oxidative stress and immune cell infiltration. Therefore, we aimed to determine biomarkers associated with oxidative stress during renal IRIs and their relationship with immune cell infiltration.

Method

A differential gene expression analysis was made based on the GSE148420 dataset from the NCBI Gene Expression Comprehensive Database (GEO) combined with 92 oxidative-stress (OS)-related genes identified in the Molecular Signatures Database. Then we identified differentially-expressed genes (DEOSGs) associated with oxidative stress, which were used for gene ontology (GO) and a Kyoto Encyclopedia of Genomes (KEGG) enrichment analysis. At the same time, we used PPI protein interaction networks and Lasso regression analysis to identify key genes, which were verified by the validation sets GSE58438 and GSE71647, as well as Western Blot detection on rat renal IRI models. At the same time, PAS staining, HE staining and immunohistochemistry were used to detect tissue damage and expression of markers related to oxidative stress during renal ischemia-reperfusion. Single-gene enrichment analysis (GSEA) was used to further clarify the underlying biological functions of key genes. Cibersort was used to analyze the immune cell infiltration during renal IRI and the correlation of key genes with immune cells. At the same time, we constructed a network of transcription-factor (TF)-Hub genes and miRNA-Hub genes. DGIDB was used to predict drugs and molecular compounds that might interact with the Hub genes.

Results

Compared with the control group, a total of 5456 differential genes (DEGs) were measured in the renal IRI group, 2486 of which were upregulated and 2970 were down-regulated. Among them, we found 30 DEGs (DEOSGs) associated with oxidative stress. The results of GO and KEGG enrichment analysis showed that these DEOSGs were mainly enriched in glutathione metabolism, the response to oxidative stress stimulation, the regulation of T cell activation and apoptosis signaling pathways. Through a protein interaction network (PPI) and a LASSO regression analysis, a total of two Hub genes were identified, namely GPX3 and GSTT1, which were validated through external validation sets and animal experiments. Through pathological methods, we found that the pathological damage of renal tissue and the expression of oxidative stress markers increased after renal ischemia-reperfusion. The results of GSEA showed that the Hub genes were related to oxidative stress pathways, apoptosis signaling pathways and immune-response-related signaling pathways. An immunoinfiltration correlation analysis showed that genes GPX3 and GSTT1 were significantly positively correlated with plasma cells and macrophage M0, while were negatively correlated with monocytes and macrophages M1 and M2. Using the Strust, Starbase and DGIDB database, we predicted that 81 transcription factors, 49 miRNAs and 13 drug or molecular compounds might interact with the Hub genes.

Conclusion

Through a comprehensive analysis of gene expression, our findings may provide new potential biomarkers for the pathogenesis of renal IRIs and a reliable basis for its early diagnosis as well as treatment.

Astragaloside IV Targets Macrophages to Alleviate Renal Ischemia-Reperfusion Injury via the Crosstalk between Hif-1α and NF-κB (p65)/Smad7 Pathways

(1) Background: Astragaloside IV (AS-IV) is derived from Astragalus membranous (AM), which is used to treat kidney disease. Macrophages significantly affect the whole process of renal ischemia-reperfusion (I/R). The regulation of macrophage polarization in kidneys by AS-IV was the focus. (2) Methods: Renal tubular injury and fibrosis in mice were detected by Hematoxylin and Eosin staining and Masson Trichrome Staining, separately. An ELISA and quantitative real-time polymerase chain reaction were used to explore the cytokine and mRNA expression. Western blot was used to determine protein expression and siRNA technology was used to reveal the crosstalk of signal pathways in RAW 264.7 under hypoxia. (3) Results: In the early stages of I/R injury, AS-IV reduced renal damage and macrophage infiltration. M1-associated markers were decreased, while M2 biomarkers were increased. The NF-κB (p65)/Hif-1α pathway was suppressed by AS-IV in M1. Moreover, p65 dominated the expression of Hif-1α. In the late stages of I/R injury, renal fibrosis was alleviated, and M2 infiltration also decreased after AS-IV treatment. Hif-1α expression was reduced by AS-IV, while Smad7 expression was enhanced. Hif-1α interferes with the expression of Smad7 in M2. (4) Conclusions: AS-IV promoted the differentiation of M1 to M2, relieving the proinflammatory response to alleviate the kidney injury during the early stages. AS-IV attenuated M2 macrophage infiltration to prevent kidney fibrosis during the later stages.

Identification of renal ischemia reperfusion injury subtypes and predictive strategies for delayed graft function and graft survival based on neutrophil extracellular trap-related genes

Background

Ischemia reperfusion injury (IRI) is an inevitable process in renal transplantation, which is closely related to serious postoperative complications such as delayed graft function (DGF), acute rejection and graft failure. Neutrophil extracellular traps (NETs) are extracellular DNA structures decorated with various protein substances released by neutrophils under strong signal stimulation. Recently, NETs have been found to play an important role in the process of IRI. This study aimed to comprehensively analyze the expression landscape of NET-related genes (NRGs) during IRI, identify clusters with different degrees of IRI and construct robust DGF and long-term graft survival predictive strategies.

Methods

The microarray and RNA-seq datasets were obtained from the GEO database. Differentially expressed NRGs (DE-NRGs) were identified by the differential expression analysis, and the NMF algorithm was used to conduct a cluster analysis of IRI samples. Machine learning algorithms were performed to screen DGF-related hub NRGs, and DGF and long-term graft survival predictive strategies were constructed based on these hub NRGs. Finally, we verified the expression of Cxcl1 and its effect on IRI and NETs generation in the mouse IRI model.

Results

This study revealed two IRI clusters (C1 and C2 clusters) with different molecular features and clinical characteristics. Cluster C1 was characterized by active metabolism, mild inflammation and lower incidence of DGF, while Cluster C2 was inflammation activated subtype with a higher incidence of DGF. Besides, based on DGF-related hub NRGs, we successfully constructed robust DGF and long-term graft survival predictive strategies. The mouse renal IRI model verified that Cxcl1 was significantly upregulated in renal tissues after IRI, and using a CXCL8/CXCL1 inhibitor could significantly improve renal function, alleviate renal tubular necrosis, tissue inflammatory response, and NET formation.

Conclusion

This study identified two distinct IRI clusters based on DE-NRGs and constructed robust prediction methods for DGF and graft survival, which can provide references for early prevention and individualized treatment of various postoperative complications after renal transplantation.

CCAAT/Enhancer-Binding Proteins in Fibrosis: Complex Roles Beyond Conventional Understanding

CCAAT/enhancer-binding proteins (C/EBPs) are a family of at least six identified transcription factors that contain a highly conserved basic leucine zipper domain and interact selectively with duplex DNA to regulate target gene expression. C/EBPs play important roles in various physiological processes, and their abnormal function can lead to various diseases. Recently, accumulating evidence has demonstrated that aberrant C/EBP expression or activity is closely associated with the onset and progression of fibrosis in several organs and tissues. During fibrosis, various C/EBPs can exert distinct functions in the same organ, while the same C/EBP can exert distinct functions in different organs. Modulating C/EBP expression or activity could regulate various molecular processes to alleviate fibrosis in multiple organs; therefore, novel C/EBPs-based therapeutic methods for treating fibrosis have attracted considerable attention. In this review, we will explore the features of C/EBPs and their critical functions in fibrosis in order to highlight new avenues for the development of novel therapies targeting C/EBPs.

Functional consequence of myeloid ferritin heavy chain on acute and chronic effects of rhabdomyolysis-induced kidney injury

Acute kidney injury (AKI) is a serious complication of rhabdomyolysis that significantly impacts survival. Myoglobin released from the damaged muscle accumulates in the kidney, causing heme iron-mediated oxidative stress, tubular cell death, and inflammation. In response to injury, myeloid cells, specifically neutrophils and macrophages, infiltrate the kidneys, and mediate response to injury. Ferritin, comprised of ferritin light chain and ferritin heavy chain (FtH), is vital for intracellular iron handling. Given the dominant role of macrophages and heme-iron burden in the pathogenesis of rhabdomyolysis, we studied the functional role of myeloid FtH in rhabdomyolysis-induced AKI and subsequent fibrosis. Using two models of rhabdomyolysis induced AKI, we found that during the acute phase, myeloid FtH deletion did not impact rhabdomyolysis-induced kidney injury, cell death or cell proliferation, suggesting that tubular heme burden is the dominant injury mechanism. We also determined that, while the kidney architecture was markedly improved after 28 days, tubular casts persisted in the kidneys, suggesting sustained damage or incomplete recovery. We further showed that rhabdomyolysis resulted in an abundance of disparate intra-renal immune cell populations, such that myeloid populations dominated during the acute phase and lymphoid populations dominated in the chronic phase. Fibrotic remodeling was induced in both genotypes at 7 days post-injury but continued to progress only in wild-type mice. This was accompanied by an increase in expression of pro-fibrogenic and immunomodulatory proteins, such as transforming growth factor-β, S100A8, and tumor necrosis factor-α. Taken together, we found that while the initial injury response to heme burden was similar, myeloid FtH deficiency was associated with lesser interstitial fibrosis. Future studies are warranted to determine whether this differential fibrotic remodeling will render these animals more susceptible to a second AKI insult or progress to chronic kidney disease at an accelerated pace.

TcpC Inhibits M1 but Promotes M2 Macrophage Polarization via Regulation of the MAPK/NF-κB and Akt/STAT6 Pathways in Urinary Tract Infection

Abstract

TcpC is a multifunctional virulence factor of Uropathogenic Escherichia coli (UPEC). Macrophages can differentiate into two different subsets M1 and M2 that play distinct roles in anti-infection immunity. Here, we investigate the influence of TcpC on M1/M2 polarization and the potential mechanisms. Our data showed that M1 markers CD86 and iNOS were significantly inhibited, while the M2 markers CD163, CD206 and Arg-1 were enhanced in macrophages in kidneys from the TcpC-secreting wild-type CFT073 (CFT073^wt)-infected pyelonephritis mouse model, compared with those in macrophages in kidneys from TcpC knockout CFT073 mutant (CFT073^Δtcpc)-infected mice. CFT073^wt or recombinant TcpC (rTcpC) treatment inhibits LPS + IFN-γ-induced CD80, CD86, TNF-α and iNOS expression, but promotes IL-4-induced CD163, CD206, Arg-1 and IL-10 expression in both human and mouse macrophage cell lines THP-1 and J774A.1. Moreover, rTcpC significantly attenuated LPS + IFN-γ-induced phosphorylation of p38, ERK, p50 and p65 but enhanced IL-4-induced phosphorylation of Akt and STAT6. These data suggest that TcpC inhibits M1 but promotes M2 macrophage polarization by down-regulation of p38, ERK/NF-κB and up-regulation of the Akt/STAT6 signaling pathway, respectively. Our findings not only illuminate the regulatory effects of TcpC on macrophage M1/M2 polarization and its related signaling pathways, but also provide a novel mechanism underlying TcpC-mediated immune evasion of macrophage-mediated innate immunity.

Simple Summary

We investigate the influence of TcpC, a multifunctional virulence factor of Uropathogenic Escherichia coli (UPEC), on M1/M2 macrophage polarization and the potential mechanisms. TcpC-secreting wild-type CFT073 (CFT073^wt) or recombinant TcpC (rTcpC) treatment inhibits LPS + IFN-γ-induced CD80, CD86, TNF-α and iNOS expression, but promotes IL-4-induced CD163, CD206, Arg-1 and IL-10 expression in CFT073^wt-infected pyelonephritis model mouse and both human and mouse macrophage cell lines THP-1 and J774A.1, respectively. Moreover, rTcpC significantly attenuated LPS + IFN-γ-induced phosphorylation of p38, ERK, p50 and p65 but en-hanced IL-4-induced phosphorylation of Akt and STAT6. These data suggest that TcpC inhibits M1 but promotes M2 macrophage polarization by down-regulation of p38, ERK/NF-κB and up-regulation of the Akt/STAT6 signaling pathway, respectively. Our findings not only illuminate the regulatory effects of TcpC on macrophage M1/M2 polarization and its related signaling pathways, but also provide a novel mechanism underlying TcpC-mediated immune evasion of macrophage-mediated innate immunity.

Identification of Subtypes and a Delayed Graft Function Predictive Signature Based on Ferroptosis in Renal Ischemia-Reperfusion Injury

Renal ischemia-reperfusion injury (IRI) is an inevitable process in kidney transplantation, leading to acute kidney injury, delayed graft function (DGF), and even graft loss. Ferroptosis is an iron-dependent regulated cell death in various diseases including IRI. We aimed to identify subtypes of renal IRI and construct a robust DGF predictive signature based on ferroptosis-related genes (FRGs). A consensus clustering analysis was applied to identify ferroptosis-associated subtypes of 203 renal IRI samples in the GSE43974 dataset. The FRG-associated DGF predictive signature was constructed using the Least Absolute Shrinkage and Selection Operator (LASSO), and its robustness was further verified in the validation set GSE37838. The present study revealed two ferroptosis-related patient clusters (pBECN1 and pNF2 cluster) in renal IRI samples based on distinct expression patterns of BECN1 and NF2 gene clusters. Cluster pBECN1 was metabolically active and closely correlated with less DGF, while pNF2 was regarded as the metabolic exhausted subtype with higher incidence of DGF. Additionally, a six-gene (ATF3, SLC2A3, CXCL2, DDIT3, and ZFP36) ferroptosis-associated signature was constructed to predict occurrence of DGF in renal IRI patients and exhibited robust efficacy in both the training and validation sets. High-risk patients tended to have more infiltration of dendritic cells, macrophages, and T cells, and they had significantly enriched chemokine-related pathway, WNT/β-catenin signaling pathway, and allograft rejection. Patients with low risks of DGF were associated with ferroptosis-related pathways such as glutathione and fatty acid metabolism pathways. In conclusion, patient stratification with distinct metabolic activities based on ferroptosis may help distinguish patients who may respond to metabolic therapeutics. Moreover, the DGF predictive signature based on FRGs may guide advanced strategies toward prevention of DGF in the early stage.