Identification of hub ferroptosis-related genes and immune infiltration in lupus nephritis using bioinformatics

Advances in research on immunocyte iron metabolism, ferroptosis, and their regulatory roles in autoimmune and autoinflammatory diseases

Autoimmune diseases commonly affect various systems, but their etiology and pathogenesis remain unclear. Currently, increasing research has highlighted the role of ferroptosis in immune regulation, with immune cells being a crucial component of the body's immune system. This review provides an overview and discusses the relationship between ferroptosis, programmed cell death in immune cells, and autoimmune diseases. Additionally, it summarizes the role of various key targets of ferroptosis, such as GPX4 and TFR, in immune cell immune responses. Furthermore, the release of multiple molecules, including damage-associated molecular patterns (DAMPs), following cell death by ferroptosis, is examined, as these molecules further influence the differentiation and function of immune cells, thereby affecting the occurrence and progression of autoimmune diseases. Moreover, immune cells secrete immune factors or their metabolites, which also impact the occurrence of ferroptosis in target organs and tissues involved in autoimmune diseases. Iron chelators, chloroquine and its derivatives, antioxidants, chloroquine derivatives, and calreticulin have been demonstrated to be effective in animal studies for certain autoimmune diseases, exerting anti-inflammatory and immunomodulatory effects. Finally, a brief summary and future perspectives on the research of autoimmune diseases are provided, aiming to guide disease treatment strategies.

Functional consequence of Iron dyshomeostasis and ferroptosis in systemic lupus erythematosus and lupus nephritis

Systemic lupus erythematosus (SLE) and its renal manifestation Lupus nephritis (LN) are characterized by a dysregulated immune system, autoantibodies, and injury to the renal parenchyma. Iron accumulation and ferroptosis in the immune effectors and renal tubules are recently identified pathological features in SLE and LN. Ferroptosis is an iron dependent non-apoptotic form of regulated cell death and ferroptosis inhibitors have improved disease outcomes in murine models of SLE, identifying it as a novel druggable target. In this review, we discuss novel mechanisms by which iron accumulation and ferroptosis perpetuate immune cell mediated pathology in SLE/LN. We highlight intra-renal dysregulation of iron metabolism and ferroptosis as an underlying pathogenic mechanism of renal tubular injury. The basic concepts of iron biology and ferroptosis are also discussed to expose the links between iron, cell metabolism and ferroptosis, that identify intracellular pro-ferroptotic enzymes and their protein conjugates as potential targets to improve SLE/LN outcomes.

APOC1 reduced anti-PD-1 immunotherapy of nonsmall cell lung cancer via the transformation of M2 into M1 macrophages by ferroptosis by NRF2/HO-1

The treatment strategy for nonsmall cell lung cancer (NSCLC) has always been a hot topic of concern, and its treatment strategies are also emerging. This experiment wants to know the effects of apolipoprotein C1 (APOC1) in immunotherapy of NSCLC. APOC1 mRNA and protein expression were upregulated in lung cancer tissue of patients with NSCLC. programmed cell death protein 1 (PD-1) mRNA expression was negatively correlated with PD-1 mRNA expression in patients. The survival rate of APOC1 high expression was lower than that of low expression in patients with NSCLC. APOC1 gene reduced the transformation of M2 into M1 macrophages (TMMM). APOC1 gene promoted cell growth, and the gene reduced ferroptosis of NSCLC. APOC1-induced nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (NRF2/HO-1) signaling pathway. Sh-APOC1 gene reduced cell growth in mice of NSCLC through the inhibition of NRF2/HO-1 signaling pathway. The inhibition of NRF2 reduced the TMMM by APOC1. The activation of NRF2 reduced the TMMM by si-APOC1. In conclusion, APOC1 reduced anti-PD-1 immunotherapy of NSCLC via the TMMM by ferroptosis by NRF2/HO-1, suggesting that targeting this mechanism of APOC1 may be a feasible strategy for anti-PD-1 immunotherapy for NSCLC.

Network pharmacology and molecular docking to elucidate the common mechanism of hydroxychloroquine treatment in lupus nephritis and IgA nephropathy

OBJECTIVE

Hydroxychloroquine (HCQ), characterized by a broad effect on immune regulation, has been widely used in the treatment of autoimmune glomerulonephritis such as lupus nephritis (LN) and immunoglobulin A nephropathy (IgAN). The current research investigates whether HCQ plays a role in the treatment of LN and IgAN through common mechanisms since the pathogenesis of both LN and IgAN is closely related to immune complex deposition, complement activation, and ultimately inflammation.

METHODS

Seventy-two common targets were obtained related to the common mechanism of HCQ treatment of LN and IgAN. Targets associated with LN and IgAN were collected based on DisGeNET, GeneCards, and OMIM databases. Possible HCQ targets were obtained from the PubChem database and PharmMapper databases. The overlapping targets of HCQ ingredients, IgAN, and LN were discovered via the Venn 2.1.0 online platform. Through the DAVID database, the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted. Cytoscape (v3.9.1) was used to build a protein-protein interaction (PPI) network. Molecular docking was performed by using AutoDockTools 1.5.6 software and PyMol software to match the binding activity between HCQ and the 10 core targets.

RESULTS

The results showed that core targets (including MMP 2, PPARG, IL-2, MAPK14, MMP 9, and SRC), three signaling pathways (including the PI3K-Akt, AGE-RAGE, and MAPK), and cell differentiation (including Th1, Th2, and Th17) might be related to the body's immunity and inflammation. These results suggested that HCQ might act on targets and pathways involved in inflammation and immune regulation to exert a common effect on the treatment of LN and IgAN.

CONCLUSIONS

The current study provided new evidence for the protective mechanism and clinical utility of HCQ against LN and IgAN.

Ferroptosis and secondary nephrosis

Secondary nephrosis is a series of chronic kidney diseases secondary to other underlying diseases, mainly manifesting as structural and functional abnormalities of the kidneys and metabolic disorders. It is one of the important causes of end-stage renal disease, with high morbidity and significant harm. Iron is an essential metal element in human cells, and ferroptosis is a non-traditional form of iron-dependent cell death, and its main mechanisms include iron accumulation, lipid metabolism disorders, abnormal amino acid metabolism, and damage to the antioxidant system. Recently studies have found that ferroptosis is involved in the occurrence and progression of secondary nephrosis, and the mechanism of ferroptosis in different secondary nephrosis vary. Therefore, an in-depth and systematic understanding of the association between ferroptosis and secondary nephrosis, as well as their specific regulatory mechanisms, can provide a theoretical basis for the diagnosis, prevention, treatment, and prognosis assessment of secondary nephrosis, laying the foundation for exploring new clinical therapeutic targets for secondary nephrosis.

Role of ferroptosis in chronic kidney disease

Chronic kidney disease (CKD) has historically been a significant global health concern, profoundly impacting both life and well-being. In the process of CKD, with the gradual loss of renal function, the incidence of various life-threatening complications, such as cardiovascular diseases, cerebrovascular accident, infection and stroke, is also increasing rapidly. Unfortunately, existing treatments exhibit limited ability to halt the progression of kidney injury in CKD, emphasizing the urgent need to delve into the precise molecular mechanisms governing the occurrence and development of CKD while identifying novel therapeutic targets. Renal fibrosis, a typical pathological feature of CKD, plays a pivotal role in disrupting normal renal structures and the loss of renal function. Ferroptosis is a recently discovered iron-dependent form of cell death characterized by lipid peroxide accumulation. Ferroptosis has emerged as a potential key player in various diseases and the initiation of organ fibrosis. Substantial evidence suggests that ferroptosis may significantly contribute to the intricate interplay between CKD and its progression. This review comprehensively outlines the intricate relationship between CKD and ferroptosis in terms of iron metabolism and lipid peroxidation, and discusses the current landscape of pharmacological research on ferroptosis, shedding light on promising avenues for intervention. It further illustrates recent breakthroughs in ferroptosis-related regulatory mechanisms implicated in the progression of CKD, thereby providing new insights for CKD treatment. Video Abstract.

Ferroptosis of CD163+ tissue-infiltrating macrophages and CD10+ PC+ epithelial cells in lupus nephritis

Background

Dysregulation of cell death and defective clearance of dying cells are closely related to the pathogenesis of lupus nephritis (LN). However, the contribution of a recently discovered form of programmed cell death (PCD) called ferroptosis to LN has not been explored in detail. The purpose of this study was to investigate the role of ferroptosis and its associated metabolic pathways in the pathogenesis of LN.

Methods

The composite gene expression scores were calculated by averaging the z-scored transformed log2 expressed genes within each form of PCD and pathway. Immunohistochemistry and immunofluorescence assays were used to verify the bioinformatics results.

Results

We determined that ferroptosis is prominently and specifically elevated in the glomerular compartment of LN patients compared to other forms of PCD and kidney disease. This finding was then verified by immunohistochemical staining of 4-HNE (a key indicator for ferroptosis) expression in our own cohort (P < 0.0001). Intercorrelation networks were observed between 4-HNE and blood urea nitrogen, SLE disease activity index, serum creatinine, and complement 4, and negatively correlated with glomerular filtration rate in our own LN cohort (P < 0.05). Furthermore, enhanced iron metabolism and reduced fatty acid synthesis may be the most important factors for ferroptosis within the glomerulus. Through analysis of a single cell sequencing dataset and verification of immunohistochemical and immunofluorescence staining, aberrantly activated lipid peroxidation in CD163+ macrophages and CD10+ PC+ (pyruvate carboxylase) epithelial cells indicated that they may be undergoing ferroptosis in the glomerular compartment.

Conclusions

Two dysregulated genes, CD163 and PC, were identified and verified that were significantly associated with lipid peroxidation. Targeting ferroptosis in CD163+ macrophages and CD10+ PC+ epithelial cells may provide novel therapeutic approaches in LN.

Machine learning identifies ferroptosis-related genes as potential diagnostic biomarkers for osteoarthritis

Background

Osteoarthritis (OA) is one of the most common forms of degenerative arthritis and a major cause of pain and disability. Ferroptosis, a novel mode of cell death, has been verified to participate in the development of OA, but its mechanism is still unclear. This paper analyzed the ferroptosis-related genes (FRGs) in OA and explored their potential clinical value.

Methods

We downloaded data through the GEO database and screened for DEGs. Subsequently, FRGs were obtained using two machine learning methods, LASSO regression and SVM-RFE. The accuracy of the FRGs as disease diagnosis was identified using ROC curves and externally validated. The CIBERSORT analyzed the immune microenvironment rug regulatory network constructed through the DGIdb. The competitive endogenous RNA (ceRNA) visualization network was constructed to search for possible therapeutic targets. The expression levels of FRGs were verified by qRT-PCR and immunohistochemistry.

Results

In this study, we found 4 FRGs. The ROC curve showed that the combined 4 FRGs had the highest diagnostic value. Functional enrichment analysis showed that the 4 FRGs in OA could influence the development of OA through biological oxidative stress, immune response, and other processes. qRT-PCR and immunohistochemistry verified the expression of these key genes, further confirming our findings. Monocytes and macrophages are heavily infiltrated in OA tissues, and the persistent state of immune activation may promote the progression of OA. ETHINYL ESTRADIOL was a possible targeted therapeutic agent for OA. Meanwhile, ceRNA network analysis identified some lncRNAs that could regulate the FRGs.

Conclusion

We identify 4 FRGs (AQP8, BRD7, IFNA4, and ARHGEF26-AS1) closely associated with bio-oxidative stress and immune response, which may become early diagnostic and therapeutic targets for OA.

Novel Insight into Ferroptosis in Kidney Diseases

BACKGROUND

Various kidney diseases such as acute kidney injury, chronic kidney disease, polycystic kidney disease, renal cancer, and kidney stones, are an important part of the global burden, bringing a huge economic burden to people around the world. Ferroptosis is a type of nonapoptotic iron-dependent cell death caused by the excess of iron-dependent lipid peroxides and accompanied by abnormal iron metabolism and oxidative stress. Over the past few decades, several studies have shown that ferroptosis is associated with many types of kidney diseases. Studying the mechanism of ferroptosis and related agonists and inhibitors may provide new ideas and directions for the treatment of various kidney diseases.

SUMMARY

In this review, we discuss the differences between ferroptosis and other types of cell death such as apoptosis, necroptosis, pyroptosis, cuprotosis, pathophysiological features of the kidney, and ferroptosis-induced kidney injury. We also provide an overview of the molecular mechanisms involved in ferroptosis and events that lead to ferroptosis. Furthermore, we summarize the possible clinical applications of this mechanism among various kidney diseases.

KEY MESSAGE

The current research suggests that future therapeutic efforts to treat kidney ailments would benefit from a focus on ferroptosis.