Peroxiredoxin 1 aggravates acute kidney injury by promoting inflammation through Mincle/Syk/NF-κB signaling

Lymphocytes and innate immune cells in acute kidney injury and repair

Acute kidney injury (AKI) is a common and serious disease entity that affects native kidneys and allografts but for which no specific treatments exist. Complex intrarenal inflammatory processes driven by lymphocytes and innate immune cells have key roles in the development and progression of AKI. Many studies have focused on prevention of early injury in AKI. However, most patients with AKI present after injury is already established. Increasing research is therefore focusing on mechanisms of renal repair following AKI and prevention of progression from AKI to chronic kidney disease. CD4+ and CD8+ T cells, B cells and neutrophils are probably involved in the development and progression of AKI, whereas regulatory T cells, double-negative T cells and type 2 innate lymphoid cells have protective roles. Several immune cells, such as macrophages and natural killer T cells, can have both deleterious and protective effects, depending on their subtype and/or the stage of AKI. The immune system not only participates in injury and repair processes during AKI but also has a role in mediating AKI-induced distant organ dysfunction. Targeted manipulation of immune cells is a promising therapeutic strategy to improve AKI outcomes.

Mefunidone alleviates silica-induced inflammation and fibrosis by inhibiting the TLR4-NF-κB/MAPK pathway and attenuating pyroptosis in murine macrophages

AIMS

Silicosis is the most common and severe type of pneumoconiosis, imposing a substantial disease burden and economic loss on patients and society. The pathogenesis and key targets of silicosis are not yet clear, and there are currently no effective treatments available. Therefore, we conducted research on mefunidone (MFD), a novel antifibrotic drug, to explore its efficacy and mechanism of action in murine silicosis.

METHODS

Acute 7-day and chronic 28-day silicosis models were constructed in C57BL/6J mice by the intratracheal instillation of silica and subsequently treated with MFD to assess its therapeutic potential. The effects of MFD on silica-induced inflammation, pyroptosis, and fibrosis were further investigated using immortalized mouse bone marrow-derived macrophages (iBMDMs).

RESULTS

In the 7-day silica-exposed mouse models, MFD treatment significantly alleviated pulmonary inflammation and notably reduced macrophage infiltration into the lung tissue. RNA-sequencing analysis of silica-induced iBMDMs followed by gene set enrichment analysis revealed that MFD profoundly influenced cytokine-cytokine receptor interactions, chemokine signaling, and the toll-like receptor signaling pathways. MFD treatment also markedly reduced the secretion of inflammatory cytokines and chemokines from silica-exposed iBMDMs. Moreover, MFD effectively downregulated the activation of the TLR4-NF-κB/MAPK signaling pathway induced by silica and mitigated the upregulation of pyroptosis markers. Additionally, MFD treatment significantly suppressed the activation of fibroblasts and alveolar epithelial cells co-cultured with silica-exposed mouse macrophages. Ultimately, in the 28-day silica-exposed mouse models, MFD administration led to a substantial reduction in the severity of pulmonary fibrosis.

CONCLUSION

MFD mitigates silica-induced pulmonary inflammation and fibrosis in mice by suppressing the TLR4-NF-κB/MAPK signaling pathway and reducing pyroptotic responses in macrophages. MFD could potentially emerge as a novel therapeutic agent for the treatment of silicosis.

Remifentanil represses oxidative stress to relieve hepatic ischemia/reperfusion injury via regulating BACH1/PRDX1 axis

BACKGROUND

Hepatic ischemia-reperfusion injury (HIRI) is a major cause of liver dysfunction after clinical liver surgery, which seriously affects the prognosis of patients. Remifentanil (RE) has been verified to attenuate HIRI. However, its therapeutic mechanism is still unclear. This study aimed to explore the protective mechanism of RE against HIRI.

METHODS

A mouse HIRI model and an in vitro model of hypoxia/reoxygenation (H/R)-stimulated AML12 hepatocytes were established. Liver histopathological changes were evaluated by hematoxylin and eosin (HE) staining. Oxidative stress damage was assessed by malondialdehyde (MDA), superoxide dismutase (SOD), and reactive oxygen species (ROS) levels. Liver function was determined by serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH). and adenosine triphosphate (ATP) levels. Cell counting kit-8 (CCK-8) assessed cell viability. Apoptosis was measured by terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) and flow cytometry. The levels of inflammatory factors were detected by enzyme-linked immunosorbent assay (ELISA) kits. The differentially expressed genes were evaluated by mRNA microarray analysis. Western blotting and real-time quantitative polymerase chain reaction (RT-qPCR) were conducted to detect molecule expression. The binding of BTB and CNC homology 1 (BACH1) to peroxiredoxin 1 (PRDX1) was validated by chromatin immunoprecipitation (ChIP) and dual luciferase reporter assay.

RESULTS

RE treatment improved liver function, and repressed oxidative stress damage and apoptosis in HIRI mice. Nine differentially expressed genes in the liver tissues of HIRI mice were selected by microarray analysis, among which BACH1 was down-regulated and PRDX1 was up-regulated after RE treatment. In addition, BACH1 directly bound to the promoter region of PRDX1 to inhibit its transcription and expression, which led to oxidative stress injury. BACH1 overexpression or PRDX1 silencing could counteract the beneficial effects of RE against HIRI.

CONCLUSION

RE suppressed oxidative stress injury and inflammation via inactivation of the BACH1/PRDX1 axis, thereby ameliorating HIRI. Our findings enrich the understanding of the protective mechanisms of RE against HIRI, and provide novel evidence for its clinical application.

Mincle receptor in macrophage and neutrophil contributes to the unresolved inflammation during the transition from acute kidney injury to chronic kidney disease

Background

Recent studies have demonstrated a strong association between acute kidney injury (AKI) and chronic kidney disease (CKD), while the unresolved inflammation is believed to be a driving force for this chronic transition process. As a transmembrane pattern recognition receptor, Mincle (macrophage-inducible C-type lectin, Clec4e) was identified to participate in the early immune response after AKI. However, the impact of Mincle on the chronic transition of AKI remains largely unclear.

Methods

We performed single-cell RNA sequencing (scRNA-seq) with the unilateral ischemia-reperfusion (UIR) murine model of AKI at days 1, 3, 14 and 28 after injury. Potential effects and mechanism of Mincle on renal inflammation and fibrosis were further validated in vivo utilizing Mincle knockout mice.

Results

The dynamic expression of Mincle in macrophages and neutrophils throughout the transition from AKI to CKD was observed. For both cell types, Mincle expression was significantly up-regulated on day 1 following AKI, with a second rise observed on day 14. Notably, we identified distinct subclusters of Minclehigh neutrophils and Minclehigh macrophages that exhibited time-dependent influx with dual peaks characterized with remarkable pro-inflammatory and pro-fibrotic functions. Moreover, we identified that Minclehigh neutrophils represented an "aged" mature neutrophil subset derived from the "fresh" mature neutrophil cluster in kidney. Additionally, we observed a synergistic mechanism whereby Mincle-expressing macrophages and neutrophils sustained renal inflammation by tumor necrosis factor (TNF) production. Mincle-deficient mice exhibited reduced renal injury and fibrosis following AKI.

Conclusion

The present findings have unveiled combined persistence of Minclehigh neutrophils and macrophages during AKI-to-CKD transition, contributing to unresolved inflammation followed by fibrosis via TNF-α as a central pro-inflammatory cytokine. Targeting Mincle may offer a novel therapeutic strategy for preventing the transition from AKI to CKD.

Rodent models of AKI and AKI-CKD transition: an update in 2024

Despite known drawbacks, rodent models are essential tools in the research of renal development, physiology, and pathogenesis. In the past decade, rodent models have been developed and used to mimic different etiologies of acute kidney injury (AKI), AKI to chronic kidney disease (CKD) transition or progression, and AKI with comorbidities. These models have been applied for both mechanistic research and preclinical drug development. However, current rodent models have their limitations, especially since they often do not fully recapitulate the pathophysiology of AKI in human patients, and thus need further refinement. Here, we discuss the present status of these rodent models, including the pathophysiologic compatibility, clinical translational significance, key factors affecting model consistency, and their main limitations. Future efforts should focus on establishing robust models that simulate the major clinical and molecular phenotypes of human AKI and its progression.

Characterization of macrophages in ischemia-reperfusion injury-induced acute kidney injury based on single-cell RNA-Seq and bulk RNA-Seq analysis

Acute kidney injury (AKI) is a complex disease, with macrophages playing a vital role in its progression. However, the mechanism of macrophage function remains unclear and strategies targeting macrophages in AKI are controversial. To address this issue, we used single-cell RNA-seq analysis to identify macrophage sub-types involved in ischemia-reperfusion-induced AKI, and then screened for associated hub genes using intersecting bulk RNA-seq data. The single-cell and bulk RNA-seq datasets were obtained from the Gene Expression Omnibus (GEO) database. Screening of differentially-expressed genes (DEGs) and pseudo-bulk DEG analyses were used to identify common hub genes. Pseudotime and trajectory analyses were performed to investigate the progression of cell differentiation. CellChat analysis was performed to reveal the crosstalk between cell clusters. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were used to identify enriched pathways in the cell clusters. Immunofluorescence and RT-PCR were preformed to validate the expression of the identified hub genes. Four hub genes, Vim, S100a6, Ier3, and Ccr1, were identified in the infiltrated macrophages between normal samples and those 3 days after ischemia-reperfusion renal injury (IRI); all were associated with the progression of IRI-induced AKI. Increased expression of Vim, S100a6, Ier3, and Ccr1 in infiltrated macrophages may be associated with inflammatory responses and may mediate crosstalk between macrophages and renal tubular epithelial cells under IRI conditions. Our results reveal that Ier3 may be critical in AKI, and that Vim, S100a6, Ier3, and Ccr1 may act as novel biomarkers and potential therapeutic targets for IRI-induced AKI.

Peroxiredoxin-1 as a molecular chaperone that regulates glutathione S-transferase P1 activity and drives mutidrug resistance in ovarian cancer cells

Ovarian cancer is among the most prevalent gynecological malignancies around the globe. Nonetheless, chemoresistance continues to be one of the greatest obstacles in the treatment of ovarian cancer. Therefore, understanding the mechanisms of chemoresistance and identifying new treatment options for ovarian cancer patients is urgently required. In this study, we found that the mRNA and protein expression levels of PRDX1 were significantly increased in cisplatin resistant A2780/CDDP cells. Cell survival assays revealed that PRDX1 depletion substantially increased ovarian cancer cell sensitivity to cisplatin, docetaxel, and doxorubicin. Additionally, PRDX1 significantly increased GSTP1 activity, resulting in multidrug resistance. Biochemical experiments showed that PRDX1 interacted with GSTP1 through Cysteine 83, which regulated GSTP1 activity as well as chemotherapy resistance in ovarian cancer cells. Our findings indicate that the molecular chaperone activity of PRDX1 is a promising new therapeutic target for ovarian cancer.