ROCK1 regulates sepsis-induced acute kidney injury via TLR2-mediated endoplasmic reticulum stress/pyroptosis axis

miR-16-5p aggravates sepsis-associated acute kidney injury by inducing apoptosis

Sepsis-associated acute kidney injury (S-AKI) is a common disease in pediatric intensive care units (ICU) with high morbidity and mortality. The newly discovered results indicate that microRNAs (miRNAs) play an important role in the diagnosis and treatment of S-AKI and can be used as markers for early diagnosis. In this study, the expression level of miR-16-5p was found to be significantly upregulated about 20-fold in S-AKI patients, and it also increased by 1.9 times in the renal tissue of S-AKI mice. Receiver operating characteristic (ROC) curve analysis showed that miR-16-5p had the highest predictive accuracy in the diagnosis of S-AKI (AUC = 0.9188). In vitro, the expression level of miR-16-5p in HK-2 cells treated with 10 μg/mL lipopolysaccharide (LPS) increased by more than 2 times. In addition, LPS-exposed renal tissue and HK-2 cells lead to upregulation of inflammatory cytokines IL-6, IL-1β, TNF-a, and kidney damage molecules kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL). However, inhibition of miR-16-5p significantly mitigated LPS expose-mediated kidney injury and inflammation. Furthermore, LPS-exposed HK-2 cells increased more than 1.7-fold the expression levels of Bax and caspase-3, decreased 3.2-fold the expression level of B-cell lymphoma-2 (Bcl-2), and significantly promoted the occurrence of apoptosis. MiR-16-5p mimic further increased LPS-induced apoptosis in HK-2 cells. Nevertheless, inhibition of miR-16-5p significantly attenuated this effect. In summary, up-regulation of miR-16-5p expression can significantly aggravate renal injury and apoptosis in S-AKI, which also proves that miR-16-5p can be used as a potential biomarker to promote early identification of S-AKI.

EIF2AK2 protein targeted activation of AIM2-mediated PANoptosis promotes sepsis-induced acute kidney injury

BACKGROUND

Acute kidney injury (AKI) frequently occurs as a complication of sepsis. PANoptosis refers to a type of inflammatory programmed cell death that exhibits key characteristics of apoptosis, necroptosis, and pyroptosis. Here, we evaluated the role of absent in melanoma 2 (AIM2) and eukaryotic translation initiation factor 2 alpha kinase 2 (EIF2AK2) in septic AKI.

METHODS

A septic AKI model was created through cecal ligation and puncture (CLP), while an in vitro model was developed using lipopolysaccharide (LPS)-stimulated HK2 cells. Hematoxylin and eosin (HE), Periodic acid-Schiff (PAS), and TUNEL staining were conducted to assess kidney injury in mice. Levels of serum creatinine (Scr) and blood urea nitrogen (BUN) were detected by kits. Gene expression was detected utilizing RT-qPCR, and Western blot was used to test protein levels. Immunofluorescence was employed to measure EIF2AK2 and AIM2 expression in mouse kidney tissue. Lactate dehydrogenase (LDH) activity assay was conducted to evaluate cytotoxicity. Co-immunoprecipitation (Co-IP) was performed to verify the binding relationship between EIF2AK2 and AIM2.

RESULTS

AIM2 expression was increased in the renal tissue of mice subjected to CLP. Activation of the inflammasome and PANoptosis were observed in the renal tissue of CLP mice. AIM2 depletion attenuated PANoptosis in LPS-treated HK-2 cells. Additionally, EIF2AK2 could directly target AIM2, leading to a positive regulation of AIM2 expression. Notably, EIF2AK2 induced PANoptosis through upregulating AIM2 in HK-2 cells stimulated by LPS.

CONCLUSIONS

Our results revealed the important role of EIF2AK2-induced AIM2 upregulation in the activation of PANoptosis during septic AKI.

H2S alleviated sepsis-induced acute kidney injury by inhibiting PERK/Bax-Bcl2 pathway

To investigate the protective mechanisms of hydrogen sulfide (H2S) in sepsis-induced acute kidney injury (SAKI), we conducted an in vivo study using a SAKI mouse model induced by intraperitoneal lipopolysaccharide (LPS) injection. Following 6 h of LPS injection, levels of tumor necrosis factor-alpha (TNF-α) and blood urea nitrogen (Bun) were significantly elevated in mouse plasma. In the kidneys of SAKI mice, expression of H2S-generating enzymes cysteinyl-tRNA synthetase (CARS), cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS) was markedly downregulated, while glucose-regulated protein 78 (GRP78), activating transcription factor 6 (ATF6), phosphorylated protein kinase R-like endoplasmic reticulum kinase/protein kinase R-like endoplasmic reticulum kinase (p-PERK/PERK), and B-cell lymphoma-2 recombinant protein X/B-cell lymphoma-2 (Bax/Bcl2) expression was significantly upregulated. H2S improved renal function and attenuated renal histopathological changes in SAKI mice, thereby alleviating LPS-induced endoplasmic reticulum stress (ERS). Additionally, it inhibited the expression of p-PERK/PERK and Bax/Bcl2. After inhibiting CSE activity with dl-propargylglycine (PPG i. p.), the renal tissue pathology in LPS-induced AKI mice was further exacerbated, leading to enhanced activation of the PERK/Bax-Bcl2 pathway. Our findings suggest that endogenous H2S influences the pathogenesis of SAKI, while exogenous H2S protects against LPS-induced AKI by inhibiting the PERK/Bax-Bcl2 pathway involved in ERS.

Caffeine and neonatal acute kidney injury

Acute kidney injury is one of the most threatening diseases in neonates, with complex pathogenesis and limited treatment options. Caffeine is a commonly used central nervous system stimulant for treating apnea in preterm infants. There is compelling evidence that caffeine may have potential benefits for preventing neonatal acute kidney injury, but comprehensive reports are lacking in this area. Hence, this review aims to provide a summary of clinical data on the potential benefits of caffeine in improving neonatal acute kidney injury. Additionally, it delves into the molecular mechanisms underlying caffeine's effects on acute kidney injury, with a focus on various aspects such as oxidative stress, adenosine receptors, mitochondrial dysfunction, endoplasmic reticulum stress, inflammasome, autophagy, p53, and gut microbiota. The ultimate goal of this review is to provide information for healthcare professionals regarding the link between caffeine and neonatal acute kidney injury and to identify gaps in our current understanding.

The roles of pyroptosis in genitourinary diseases

Pyroptosis, a form of programmed cell death distinct from apoptosis and necrosis, is thought to be closely associated with the pathogenesis of diseases. Recently, the association between pyroptosis and urinary diseases has attracted considerable attention, and a comprehensive review focusing on this issue is not available. In this study, we reviewed the role of pyroptosis in the development and progression of benign urinary diseases and urinary malignancies. Based on this, pyroptosis has been implicated in the development of urinary diseases. In summary, this review sheds light on future research directions and provides novel ideas for using pyroptosis as a powerful tool to fight urinary diseases.

Pyroptosis: The Determinator of Cell Death and Fate in Acute Kidney Injury

Background

Acute kidney injury (AKI) is kidney damage that leads to a rapid decline in function. AKI primarily occurs when the tubular epithelium is damaged, causing swelling, loss of brush margin, and eventual apoptosis. Research has shown that tubular epithelial cell damage in AKI is linked to cell cycle arrest, autophagy, and regulation of cell death.

Summary

Pyroptosis, a type of programmed cell death triggered by inflammation, is believed to play a role in the pathophysiology of AKI. Cumulative evidence has shown that pyroptosis is the main cause of tubular cell death in AKI. Thus, targeted intervention of pyroptosis may be a promising therapeutic approach for AKI. This review delves deep into the cutting-edge research surrounding pyroptosis in the context of AKI, shedding light on its intricate mechanisms and potential implications for clinical practice. Additionally, we explore the exciting realm of potential preclinical treatment options for AKI, aiming to pave the way for future therapeutic advancements.

Key Messages

Pyroptosis, a highly regulated form of cell death, plays a crucial role in determining the fate of cells during the development of AKI. This intricate process involves the activation of inflammasomes, which are multi-protein complexes that initiate pyroptotic cell death. By understanding the mechanisms underlying pyroptosis, researchers aim to gain insights into the pathogenesis of AKI and potentially identify new therapeutic targets for this condition.

Artesunate Induces Ferroptosis in Hepatic Stellate Cells and Alleviates Liver Fibrosis via the ROCK1/ATF3 Axis

Background and Aims

Development of fibrosis in chronic liver disease requires activation of hepatic stellate cells (HSCs) and leads to a poor outcome. Artesunate (Art) is an ester derivative of artemisinin that can induce ferroptosis in HSCs, and activated transcriptional factor 3 (ATF3) is an ATF/CREB transcription factor that is induced in response to stress. In this study, we examined the role of the Rho-associated protein kinase 1 (ROCK1)/ATF3 axis in Art-induced ferroptosis in HSCs.

Methods

HSC activation and ferroptosis were studied in vitro by western blotting, polymerase chain reaction, immunofluorescence, and other assays. ATF3 electrophoretic mobility and ROCK1 protein stability were assayed by western blotting. Immunoprecipitation was used to detect the interaction of ROCK1 and ATF3, as well as ATF3 phosphorylation. A ubiquitination assay was used to verify ROCK1 degradation. Atf3-interfering and Rock1-overexpressing mice were constructed to validate the anti-hepatic fibrosis activity of Art in vivo.

Results

Art induced ferroptosis in HSCs following glutathione-dependent antioxidant system inactivation resulting from nuclear accumulation of unphosphorylated ATF3 mediated by ROCK1-ubiquitination in vitro. Art also decreased carbon tetrachloride-induced liver fibrosis in mice, which was reversed by interfering with Atf3 or overexpressing Rock1.

Conclusions

The ROCK1/ATF3 axis was involved in liver fibrosis and regulation of ferroptosis, which provides an experimental basis for further study of Art for the treatment of liver fibrosis.

Platelet Exosome-Derived miR-223-3p Regulates Pyroptosis in the Cell Model of Sepsis-Induced Acute Renal Injury by Targeting Mediates NLRP3

BACKGROUND

The present study investigated the roles and mechanisms of platelet-derived exosomes in sepsis-induced acute renal injury.

METHODS

The blood samples of septic patients and healthy controls were collected for clinical examination. The plasma levels of miR-223-3p and NLRP3 mRNA were analyzed by qRT-PCR and the serum IL-1β and creatinine levels were quantified by enzyme-linked immunosorbent assay (ELISA). C57BL/6 mice injected with LPS (lipopolysaccharide) were employed as the animal model for sepsis-induced acute renal injury. Human coronary artery endothelial cells (HCAECs) were treated with TNF-α as a cellular model for sepsis-induced endothelial damages.

RESULTS

The number of PMP (platelet-derived microparticles) in patients with sepsis was increased. The level of miR-223-3p in the platelet exosomes isolated from the serum sample in patients with sepsis was significantly lower than that of the healthy controls. The level of miR-223-3p was also decreased in the platelet exosomes of mouse model with sepsis-induced acute renal injury. Downregulating miR-223-3p promoted sepsis-induced acute renal injury in mice model, while the administration of miR-223-3p reduced the inflammation in endothelial cells of sepsis-induced acute renal injury. NLRP3 (NLR Family Pyrin Domain Containing 3) was identified as one target of miR-223-3p in the platelet exosomes of sepsis-induced acute kidney injury. miR-223-3p attenuated NLRP3-induced pyroptosis in endothelial cell model of sepsis-induced acute kidney injury.

CONCLUSION

Our data suggest that platelet exosome-derived miR-223-3p negatively regulates NLRP3-dependent inflammasome to suppress pyroptosis in endothelial cells. Decreased miR-223-3p expression promotes the inflammation in sepsis-induced acute renal injury. Targeting miR-223-3p may be developed into a therapeutic approach for sepsis-induced acute renal injury.

Research Progress of Pyroptosis in Renal Diseases

Kidney diseases, particularly Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD), are identified as global public health issues affecting millions of individuals. In addition, the frequency of renal diseases in the population has increased dramatically and rapidly in recent years. Renal disorders have become a significant public health burden. The pathophysiology of renal diseases is significantly connected with renal cell death, including apoptosis, necrosis, necroptosis, ferroptosis, pyroptosis, and autophagy, as is now recognized. Unlike other forms of cell death, pyroptosis is a unique planned cell death (PCD). Scientists have proven that pyroptosis is crucial in developing various disorders, and this phenomenon is gaining increasing attention. It is considered a novel method of inflammatory cell death. Intriguingly, inflammation is among the most significant pathological characteristics of renal disease. This study investigates the effects of pyroptosis on Acute Kidney Injury (AKI), Chronic Kidney Disease (CKD), Diabetic Nephropathy (DN), Immunoglobulin A (IgA) Nephropathy, and Lupus Nephritis (LN) to identify novel therapeutic targets for kidney diseases.

EIF2α/ATF4 pathway enhances proliferation of mesangial cell via cyclin D1 during endoplasmic reticulum stress in IgA nephropathy

IgA nephropathy (IgAN) is an essential cause of kidney failure and end-stage kidney disease worldwide. Mesangial hypercellularity is an important characteristic of IgAN, but the underlying mechanism remains unclear. Endoplasmic reticulum (ER) stress is a series of stress responses to restore the function of endoplasmic reticulum. We aimed to explore how ER stress functioned in kidneys of IgAN. We first examined ER stress in IgAN kidneys in vivo and in vitro, by testing the levels of ER stress associated proteins (BIP, p-eIF2α and ATF4). Our results showed that ER stress was activated in IgAN patients, mice and cell model. ER stress activation was related to the distribution of IgA deposition and the degree of mesangial proliferation. To determine the role of ER stress in mesangial cell (MC) proliferation of IgAN, we then tested the levels of ER stress and MC proliferation (cyclin D1, cell viability and cell cycle) through inhibiting ER stress associated proteins. After inhibiting ER stress associated proteins, ER stress was inactivated and cell proliferation was inhibited in MCs. We also explored the correlation between ER stress in the glomerulus and the clinical outcomes of IgAN patients in a prospective study. Patients with lower expression of p-eIF2α or ATF4 had higher rates of hematuria remission, proteinuria remission and clinical remission. In summary, our work outlines that in IgAN, ER stress mediated by eIF2α/ATF4 pathway promotes MC proliferation via up-regulating the expression of cyclin D1. Furthermore, p-eIF2α and ATF4 in the glomerulus negatively correlate with the clinical remission of IgAN patients.

Knockout of Erbin promotes pyroptosis via regulating NLRP3/caspase-1/Gasdermin D pathway in sepsis-induced acute kidney injury

BACKGROUND

This study aims to investigate the correlation between Erbin and sepsis, and the role of Erbin on the pyroptosis pathway in acute kidney injury caused by sepsis and NLRP3/caspase-1/Gasdermin D pathway.

METHODS

In the study, lipopolysaccharide (LPS) treatment or cecal ligation and puncture (CLP) surgery on mice were used to stimulate the in vitro and in vivo sepsis-induced renal injury model. The male C57BL/6 of wild-type mice (WT) and Erbin-knockout mice (Erbin-/-, EKO) were randomly divided into four groups (WT + Sham, WT + CLP, EKO + Sham, EKO + CLP). Inflammatory cytokine, renal function, pyroptotic cell numbers and the levels of protein and mRNA expression of pyroptosis, including the NLRP3 (all P < 0.05), were analyzed and found increase in Erbin-/- mice with CLP and LPS-induced HK-2 cells.

RESULTS

The inhibited of Erbin shows a renal damaged effect by promoting NLRP3 inflammasome-mediated pyroptosis in SI-AKI.

CONCLUSION

This study demonstrated a novel mechanism by which Erbin regulates NLRP3 inflammasome-mediated pyroptosis in SI-AKI.

Liensinine pretreatment reduces inflammation, oxidative stress, apoptosis, and autophagy to alleviate sepsis acute kidney injury

Liensinine is mainly derived from alkaloids extracted and isolated from lotus seeds (Nelumbo nucifera Gaertn). It possesses anti-inflammatory, and antioxidant, according to contemporary pharmacological investigations. However, the effects and therapeutic mechanisms of liensinine on acute kidney injury (AKI) models of sepsis are unclear. To gain insight into these mechanisms, we established a sepsis kidney injury model by LPS injection of mice treated with liensinine, and stimulation of HK-2 with LPS in vitro and treated with liensinine and inhibitors of p38 MAPK, JNK MAPK. We first found that liensinine significantly reduced kidney injury in sepsis mice, while suppressing excessive inflammatory responses, restoring renal oxidative stress-related biomarkers, reducing increased apoptosis in TUNEL-positive cells and excessive autophagy, and that this process was accompanied by an increase in JNK/ p38-ATF 2 axis. In vitro experiments further demonstrated that lensinine reduced the expression of KIM-1, NGAL, inhibited pro- and anti-inflammatory secretion disorders, regulated the activation of the JNK/p38-ATF 2 axis, and reduced the accumulation of ROS, as well as the reduction of apoptotic cells detected by flow cytometry, and that this process played the same role as that of p38 MAPK, JNK MAPK inhibitors. We speculate that liensinine and p38 MAPK, JNK MAPK inhibitors may act on the same targets and could be involved in the mechanism of alleviating sepsis kidney injury in part through modulation of the JNK/p38-ATF 2 axis. Our study demonstrates that lensinine is a potential drug and thus provides a potential avenue for the treatment of AKI.

Sepsis-mediated renal dysfunction: Pathophysiology, biomarkers and role of phytoconstituents in its management

Sepsis has evolved as an enormous health issue amongst critically ill patients. It is a major risk factor that results in multiple organ failure and shock. Acute kidney injury (AKI) is one of the most frequent complications underlying sepsis, which portends a heavy burden of mortality and morbidity. Thus, the present review is aimed to provide an insight into the recent progression in the molecular mechanisms targeting dysregulated immune response and cellular dysfunction involved in the development of sepsis-associated AKI, accentuating the phytoconstituents as eligible candidates for attenuating the onset and progression of sepsis-associated AKI. The pathogenesis of sepsis-mediated AKI entails a complicated mechanism and is likely to involve a distinct constellation of hemodynamic, inflammatory, and immune mechanisms. Novel biomarkers like neutrophil gelatinase-associated lipocalin, soluble triggering receptor expressed on myeloid cells 1, procalcitonin, alpha-1-microglobulin, and presepsin can help in a more sensitive diagnosis of sepsis-associated AKI. Many bioactive compounds like curcumin, resveratrol, baicalin, quercetin, and polydatin are reported to play an important role in the prevention and management of sepsis-associated AKI by decreasing serum creatinine, blood urea nitrogen, cystatin C, lipid peroxidation, oxidative stress, IL-1β, TNF-α, NF-κB, and increasing the activity of antioxidant enzymes and level of PPARγ. The plant bioactive compounds could be developed into a drug-developing candidate in managing sepsis-mediated acute kidney injury after detailed follow-up studies. Lastly, the gut-kidney axis may be a more promising therapeutic target against the onset of septic AKI, but a deeper understanding of the molecular pathways is still required.

Comprehensive analysis of endoplasmic reticulum stress-associated genes signature of ulcerative colitis

Background

Endoplasmic reticulum stress (ERS) is a critical factor in the development of ulcerative colitis (UC); however, the underlying molecular mechanisms remain unclear. This study aims to identify pivotal molecular mechanisms related to ERS in UC pathogenesis and provide novel therapeutic targets for UC.

Methods

Colon tissue gene expression profiles and clinical information of UC patients and healthy controls were obtained from the Gene Expression Omnibus (GEO) database, and the ERS-related gene set was downloaded from GeneCards for analysis. Weighted gene co-expression network analysis (WGCNA) and differential expression analysis were utilized to identify pivotal modules and genes associated with UC. A consensus clustering algorithm was used to classify UC patients. The CIBERSORT algorithm was employed to evaluate the immune cell infiltration. Gene Set Variation Analysis (GSVA), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to explore potential biological mechanisms. The external sets were used to validate and identify the relationship of ERS-related genes with biologics. Small molecule compounds were predicted using the Connectivity Map (CMap) database. Molecular docking was performed to simulate the binding conformation of small molecule compounds and key targets.

Results

The study identified 915 differentially expressed genes (DEGs) and 11 ERS-related genes (ERSRGs) from the colonic mucosa of UC patients and healthy controls, and these genes had good diagnostic value and were highly correlated. Five potential small-molecule drugs sharing tubulin inhibitors were identified, including albendazole, fenbendazole, flubendazole, griseofulvin, and noscapine, among which noscapine exhibited the highest correlation with a high binding affinity to the targets. Active UC and 10 ERSRGs were associated with a large number of immune cells, and ERS was also associated with colon mucosal invasion of active UC. Significant differences in gene expression patterns and immune cell infiltration abundance were observed among ERS-related subtypes.

Conclusion

The results suggest that ERS plays a vital role in UC pathogenesis, and noscapine may be a promising therapeutic agent for UC by affecting ERS.

lncRNA NEAT1 mediates LPS-induced pyroptosis of BEAS-2B cells via targeting miR-26a-5p/ROCK1 axis

Acute lung injury (ALI) is an adverse disease of the respiratory system, and one of its prevalent causes is sepsis induction. Cell pyroptosis facilitates the progression of ALI and lncRNAs play critical roles in ALI. Thus, this research seeks to investigate the specific mechanism of NEAT1 in sepsis-ALI.BEAS-2B cells were exposed to lipopolysaccharide (LPS) to construct a cell model of sepsis-induced ALI. The gene and protein expression were assessed using qRT-PCR and western blot. Cell viability was identified by CCK-8. Cell death was discovered using PI staining. The secretion of IL-1β and IL-18 was examined using ELISA. The interconnections among NEAT1, miR-26a-5p, and ROCK1 were confirmed using starbase, luciferase assay, and RIP.LPS treatment augmented NEAT1 and ROCK1 levels while mitigating miR-26a-5p level in BEAS-2B cells. Additionally, LPS treatment facilitated cell death and cell pyroptosis, whereas NEAT1 silencing could reverse these effects in BEAS-2B cells. Mechanistically, NEAT1 positively mediated ROCK1 expression by targeting miR-26a-5p. Furthermore, miR-26a-5p inhibitor offset NEAT1 depletion-mediated suppressive effects on cell death and cell pyroptosis. ROCK1 upregulation decreased the inhibitory impacts produced by miR-26a-5p overexpression on cell death and cell pyroptosis. Our outcomes demonstrated NEAT1 could reinforce LPS-induced cell death and cell pyroptosis by repressing the miR-26a-5p/ROCK1 axis, thereby worsening ALI caused by sepsis. Our data indicated NEAT1, miR-26a-5p, and ROCK1 might be biomarkers and target genes for relieving sepsis-induced ALI.

Toll-like receptors 2 and 4 stress signaling and sodium-glucose cotransporter-2 in kidney disease

Kidney disease is the 6th fastest-growing cause of death and a serious global health concern that urges effective therapeutic options. The inflammatory response is an initial reaction from immune and parenchymal cells in kidney diseases. Toll-like receptors (TLR) 2 and 4 are highly expressed by various kidney cells and respond to 'signaling danger' proteins, such as high mobility group box binding protein 1 (HMGB1) and prompt the progression of kidney disease by releasing inflammatory mediators. Burgeoning reports suggest that both SGLT2 and ER stress elevates TLR2/4 signaling via different axis. Moreover, SGLT2 signaling aggravates inflammation under the disease condition by promoting the NLR family pyrin domain-containing three inflammasomes and ER stress. Intriguingly, TLR2/4 downstream adaptors activate ER stress regulators. The above-discussed interactions imply that TLR2/4 does more than immune response during kidney disease. Here, we discuss in detail evidence of the roles and regulation of TLR2/4 in the context of a relationship between ER stress and SGLT2. Also, we highlighted different preclinical studies of SGLT2 inhibitors against TLR2/4 signaling in various kidney diseases. Moreover, we discuss the observational and interventional evidence about the relation between TLR2/4, ER stress, and SGLT2, which may represent the TLR2/4 as a potential therapeutic target for kidney disease.

Chemokine CCL2 from proximal tubular epithelial cells contributes to sepsis-induced acute kidney injury

Damage-associated molecular patterns secreted from activated kidney cells initiate inflammatory response, a critical step in the development of sepsis-induced acute kidney injury (AKI). However, the underlying mechanism remains to be clarified. Here, we established a mouse model of sepsis-induced AKI through intraperitoneal injection of lipopolysaccharide (LPS), and demonstrated that LPS induced dramatical upregulation of C-C motif chemokine ligand 2 (CCL2) at both the mRNA and the protein levels in kidney, which was mainly expressed by tubular epithelial cells (TECs), especially by proximal TECs. Proximal tubule-specific ablation of CCL2 reduced LPS-induced macrophage infiltration, proinflammatory cytokine expression, and attenuated AKI. In vitro, using transwell migration assay, we found that deficiency of CCL2 in TECs decreased macrophage migration ability. However, myeloid-specific depletion of CCL2 could not protect the kidneys from the aforementioned effects. Mechanistically, LPS activated toll like receptor (TLR) 2 signaling in TECs, which induced activation of its downstream effector nuclear factor (NF)-κB. Blockade of TLR2 signaling or inhibition of NF-κB activation in TECs significantly suppressed LPS-induced CCL2 expression. Furthermore, ChIP analyses confirmed a direct binding of NF-κB p65 in the CCL2 promoter regein, and LPS increased the binding of NF-κB p65 to CCL2 promoter, suggesting that TLR2/NF-κB p65 regulates CCL2 expression in TECs. Together, these results demonstrate that endogenous CCL2 released from PTECs, not from myeloid cells was responsible for sepsis-induced kidney inflammation and AKI. Specificly targeting tubular TLR2/NF-κB/CCL2 signaling may be a potential therapeutic strategy for prevention or attenuation of septic AKI.

Integrated Single Cell and Bulk RNA-Seq Analysis Revealed Immunomodulatory Effects of Ulinastatin in Sepsis: A Multicenter Cohort Study

Sepsis is a leading cause of morbidity and mortality in the intensive care unit, which is caused by unregulated inflammatory response leading to organ injuries. Ulinastatin (UTI), an immunomodulatory agent, is widely used in clinical practice and is associated with improved outcomes in sepsis. But its underlying mechanisms are largely unknown. Our study integrated bulk and single cell RNA-seq data to systematically explore the potential mechanisms of the effects of UTI in sepsis. After adjusting for potential confounders in the negative binomial regression model, there were more genes being downregulated than being upregulated in the UTI group. These down-regulated genes were enriched in the neutrophil involved immunity such as neutrophil activation and degranulation, indicating the immunomodulatory effects of UTI is mediated via regulation of neutrophil activity. By deconvoluting the bulk RNA-seq samples to obtain fractions of cell types, the Myeloid-derived suppressor cells (MDSC) were significantly expanded in the UTI treated samples. Further cell-cell communication analysis revealed some signaling pathways such as ANEEXIN, GRN and RESISTIN that might be involved in the immunomodulatory effects of UTI. The study provides a comprehensive reference map of transcriptional states of sepsis treated with UTI, as well as a general framework for studying UTI-related mechanisms.

The pathological role of damaged organelles in renal tubular epithelial cells in the progression of acute kidney injury

Acute kidney injury (AKI) is a common clinical condition associated with high morbidity and mortality. The pathogenesis of AKI has not been fully elucidated, with a lack of effective treatment. Renal tubular epithelial cells (TECs) play an important role in AKI, and their damage and repair largely determine the progression and prognosis of AKI. In recent decades, it has been found that the mitochondria, endoplasmic reticulum (ER), lysosomes, and other organelles in TECs are damaged to varying degrees in AKI, and that they can influence each other through various signaling mechanisms that affect the recovery of TECs. However, the association between these multifaceted signaling platforms, particularly between mitochondria and lysosomes during AKI remains unclear. This review summarizes the specific pathophysiological mechanisms of the main TECs organelles in the context of AKI, particularly the potential interactions among them, in order to provide insights into possible novel treatment strategies.

The Programmed Cell Death of Macrophages, Endothelial Cells, and Tubular Epithelial Cells in Sepsis-AKI

Sepsis is a systemic inflammatory response syndrome caused by infection, following with acute injury to multiple organs. Sepsis-induced acute kidney injury (AKI) is currently recognized as one of the most severe complications related to sepsis. The pathophysiology of sepsis-AKI involves multiple cell types, including macrophages, vascular endothelial cells (ECs) and renal tubular epithelial cells (TECs), etc. More significantly, programmed cell death including apoptosis, necroptosis and pyroptosis could be triggered by sepsis in these types of cells, which enhances AKI progress. Moreover, the cross-talk and connections between these cells and cell death are critical for better understanding the pathophysiological basis of sepsis-AKI. Mitochondria dysfunction and oxidative stress are traditionally considered as the leading triggers of programmed cell death. Recent findings also highlight that autophagy, mitochondria quality control and epigenetic modification, which interact with programmed cell death, participate in the damage process in sepsis-AKI. The insightful understanding of the programmed cell death in sepsis-AKI could facilitate the development of effective treatment, as well as preventive methods.