Pathological mechanisms and crosstalk among different forms of cell death in systemic lupus erythematosus

Intricating connections: the role of ferroptosis in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory and autoimmune disease with multiple tissue damage. However, the pathology remains elusive, and effective treatments are lacking. Multiple types of programmed cell death (PCD) implicated in SLE progression have recently been identified. Although ferroptosis, an iron-dependent form of cell death, has numerous pathophysiological features similar to those of SLE, such as intracellular iron accumulation, mitochondrial dysfunction, lipid metabolism disorders and concentration of damage associated-molecular patterns (DAMPs), only a few reports have demonstrated that ferroptosis is involved in SLE progression and that the role of ferroptosis in SLE pathogenesis continues to be neglected. Therefore, this review elucidates the potential intricate relationship between SLE and ferroptosis to provide a reliable theoretical basis for further research on ferroptosis in the pathogenesis of SLE.

Identification and validation of key autophagy-related genes in lupus nephritis by bioinformatics and machine learning

INTRODUCTION

Lupus nephritis (LN) is one of the most frequent and serious organic manifestations of systemic lupus erythematosus (SLE). Autophagy, a new form of programmed cell death, has been implicated in a variety of renal diseases, but the relationship between autophagy and LN remains unelucidated.

METHODS

We analyzed differentially expressed genes (DEGs) in kidney tissues from 14 LN patients and 7 normal controls using the GSE112943 dataset. Key modules and their contained genes were identified utilizing weighted gene co-expression network analysis (WGCNA). Differentially expressed autophagy-related genes (DE-ARGs) among DEGs, key module genes and autophagy-related genes (ARGs) were obtained by venn plot, and subjected to protein-protein interaction network construction. Two machine learning methods were applied to identify signature genes. The area under the receiver operating characteristic (ROC) curves was used to assess the accuracy of the signature genes. We also analyzed immune cell infiltration in LN. Additionally, the association between key genes and kidney diseases was predicted. Finally, key genes expression in kidney was verified by clinical samples and animal experiments.

RESULTS

A total of 10304 DEGs were identified in GSE1129943 and 29 modules were identified in WGCNA. Among them, the brown module and coral 2 module exhibited significant correlation with LN (cor = 0.86, -0.84, p<0.001). Machine learning techniques identified 5 signature genes, but only 2 were validated in the external dataset GSE32591, namely MAP1LC3B (AUC = 0.920) and TNFSF10 (AUC = 0.937), which are involved in autophagy and apoptosis. Immune infiltration analysis suggested that these key genes may be associated with immune cell infiltration in LN. In addition, these genes have been linked to a variety of renal diseases, and their expression was verified in kidney tissues in LN patients and lupus mice.

CONCLUSION

MAP1LC3B and TNFSF10 may be key autophagy-related genes in LN. These key genes have the potential to provide new insights into the molecular diagnosis and treatment of LN.

Serum HMGB-1 released by ferroptosis and necroptosis as a novel potential biomarker for systemic lupus erythematosus

High mobility group box proterin-1 (HMGB-1) is a multifunctional protein that can be released by various programmed cell deaths (PCDs), such as necroptosis and ferroptosis. PCDs play a critical role in the pathogenesis of systemic lupus erythematosus (SLE). However, the role of HMGB-1 in the process of SLE remains unclear. This study aims to demonstrate the potential diagnosing role of serum HMGB-1 in SLE that released by necroptosis and ferroptosis. We found that the serum levels of HMGB-1, receptor-interacting protein kinase 3 (RIPK3) /mixed lineage kinase domain-like protein (MLKL) related with necroptosis, and metabolites associated with ferroptosis were significantly upregulated in SLE patients compared to HC individuals. These serum levels were positively correlated with SLE disease activity. Additionally, the serum level of HMGB-1 showed a strong positive correlated with the levels of RIPK3/MLKL and ferroptosis metabolites. Moreover, the serum level of HMGB-1 was correlated with renal involvement and high-antinuclear antibodies (ANA) titer. After SLE serum and interferon γ (IFN-γ) treatment in vitro, the level of necroptosis and ferroptosis markers were activated and HMGB1 was released both in HEK293 and HK2 cells. Clinically, HMGB-1 was considered as a significant independent risk factor in SLE serum by binary logistic assay. Notably, HMGB-1 exhibited outstanding diagnostic ability for SLE by the area under the curve (AUC) in receiver operating characteristic (ROC) curve analysis. Taken together, our study indicates that the serum level of HMGB-1 is a promising biomarker for the diagnosis and monitoring of SLE.

Pathological mechanisms and crosstalk among various cell death pathways in cardiac involvement of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prevalent autoimmune disease primarily characterized by the involvement of multiple systems and organs. Cardiovascular disease is the primary cause of mortality in patients with SLE, though the mechanisms underlying the increased cardiovascular risk in SLE patients remain unclear. Recent studies indicate that abnormal activation of programmed cell death (PCD) signaling and the crosstalk among various forms of cell death are critical in the immunopathogenesis of SLE. Furthermore, apoptosis, necroptosis, pyroptosis, NETosis, and ferroptosis are recognized as key cellular processes in the pathogenesis of SLE and are closely linked to cardiac involvement. This review uniquely explores the intricate crosstalk between apoptosis, necroptosis, and other cell death pathways, discussing their roles and interactions in the pathogenesis of cardiac involvement in SLE. Investigating the interplay between PCD signaling and cardiac involvement in SLE in understanding the disease's underlying mechanisms and offers opportunities for new therapeutic interventions. The integration of precision medicine and innovative strategies targeting these complex pathways holds promise for enhancing the treatment prospects of SLE with cardiac involvement.

Molecular characterization analysis of PANoptosis-related genes in colorectal cancer based on bioinformatic analysis

Colorectal cancer (CRC) ranks as the third most prevalent cancer globally and stands as the second principal contributor to cancer-related fatalities. Recently, emerging research has emphasized the role of pan apoptosis (PANoptosis) in tumor development and anti-tumor therapy. In the course of this investigation, we meticulously identified and conducted a correlation analysis between differentially expressed genes associated with PANoptosis in CRC (CPAN_DEGs) and the proportion of immune cells. Subsequently, we formulated a prognostic score based on the CPAN_DEGs. Further our analysis revealed a noteworthy reduction in UNC5D mRNA expression within HCT116, HT29 and SW480 cells, as validated by qRT-PCR assay. Furthermore, scrutinizing the TCGA database unveiled a distinctive trend wherein individuals with the low UNC5D expression exhibited significantly reduced overall survival compared to their counterparts with the high UNC5D levels. The drug susceptibility analysis of UNC5D was further performed, which showed that UNC5D was corassociated with the sensitivity of CRC to 6-Thioguanine. The outcomes of our investigation underscore the mechanisms by which PANoptosis influences immune dysregulation as well as prognostic outcome in CRC.

C5a-C5aR1 axis controls mitochondrial fission to promote podocyte injury in lupus nephritis

Podocytes are essential to maintaining the integrity of the glomerular filtration barrier, but they are frequently affected in lupus nephritis (LN). Here, we show that the significant upregulation of Drp1S616 phosphorylation in podocytes promotes mitochondrial fission, leading to mitochondrial dysfunction and podocyte injury in LN. Inhibition or knockdown of Drp1 promotes mitochondrial fusion and protects podocytes from injury induced by LN serum. In vivo, pharmacological inhibition of Drp1 reduces the phosphorylation of Drp1S616 in podocytes in lupus-prone mice. Podocyte injury is reversed when Drp1 is inhibited, resulting in the alleviation of proteinuria. Mechanistically, complement component C5a (C5a) upregulates the phosphorylation of Drp1S616 and promotes mitochondrial fission in podocytes. Moreover, the expression of C5a receptor 1 (C5aR1) is notably upregulated in podocytes in LN. C5a-C5aR1 axis-controlled phosphorylation of Drp1S616 and mitochondrial fission are substantially suppressed when C5aR1 is knocked down by siRNA. Moreover, lupus-prone mice treated with C5aR inhibitor show reduced phosphorylation of Drp1S616 in podocytes, resulting in significantly less podocyte damage. Together, this study uncovers a novel mechanism by which the C5a-C5aR1 axis promotes podocyte injury by enhancing Drp1-mediated mitochondrial fission, which could have significant implications for the treatment of LN.

Therapeutic potential of MCC950, a specific inhibitor of NLRP3 inflammasome in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder with a pathogenesis that remains incompletely understood, resulting in limited treatment options. MCC950, a highly specific NLRP3 inflammasome inhibitor, effectively suppresses the activation of NLRP3, thus reducing the production of caspase-1, the pro-inflammatory cytokines IL-1β and IL-18. This review highlights the pivotal role of NLRP3 inflammasome activation pathways in the pathogenesis of SLE and discusses the potential therapeutic application of MCC950 in SLE. Notably, it comprehensively elucidates the mechanism of MCC950 targeting the NLRP3 pathway in SLE treatment, outlining its potential role in regulating autophagy and necroptosis. The insights gained contribute to a deeper understanding of the value of MCC950 in SLE therapy, serving as a robust foundation for further research and potential clinical applications.

Leveraging Lymphatic System Targeting in Systemic Lupus Erythematosus for Improved Clinical Outcomes

The role of advanced drug delivery strategies in drug repositioning and minimizing drug attrition rates, when applied early in drug discovery, is poised to increase the translational impact of various therapeutic strategies in disease prevention and treatment. In this context, drug delivery to the lymphatic system is gaining prominence not only to improve the systemic bioavailability of various pharmaceutical drugs but also to target certain specific diseases associated with the lymphatic system. Although the role of the lymphatic system in lupus is known, very little is done to target drugs to yield improved clinical benefits. In this review, we discuss recent advances in drug delivery strategies to treat lupus, the various routes of drug administration leading to improved lymph node bioavailability, and the available technologies applied in other areas that can be adapted to lupus treatment. Moreover, this review also presents some recent findings that demonstrate the promise of lymphatic targeting in a preclinical setting, offering renewed hope for certain pharmaceutical drugs that are limited by efficacy in their conventional dosage forms. These findings underscore the potential and feasibility of such lymphatic drug-targeting approaches to enhance therapeutic efficacy in lupus and minimize off-target effects of the pharmaceutical drugs. SIGNIFICANCE STATEMENT: The World Health Organization estimates that there are currently 5 million humans living with some form of lupus. With limited success in lupus drug discovery, turning to effective delivery strategies with existing drug molecules, as well as those in the early stage of discovery, could lead to better clinical outcomes. After all, effective delivery strategies have been proven to improve treatment outcomes.

CSNK1A1/CK1α suppresses autoimmunity by restraining the CGAS-STING1 signaling

STING1 (stimulator of interferon response cGAMP interactor 1) is the quintessential protein in the CGAS-STING1 signaling pathway, crucial for the induction of type I IFN (interferon) production and eliciting innate immunity. Nevertheless, the overactivation or sustained activation of STING1 has been closely associated with the onset of autoimmune disorders. Notably, the majority of these disorders manifest as an upregulated expression of type I interferons and IFN-stimulated genes (ISGs). Hence, strict regulation of STING1 activity is paramount to preserve immune homeostasis. Here, we reported that CSNK1A1/CK1α, a serine/threonine protein kinase, was essential to prevent the overactivation of STING1-mediated type I IFN signaling through autophagic degradation of STING1. Mechanistically, CSNK1A1 interacted with STING1 upon the CGAS-STING1 pathway activation and promoted STING1 autophagic degradation by enhancing the phosphorylation of SQSTM1/p62 at serine 351 (serine 349 in human), which was critical for SQSTM1-mediated STING1 autophagic degradation. Consistently, SSTC3, a selective CSNK1A1 agonist, significantly attenuated the response of the CGAS-STING1 signaling by promoting STING1 autophagic degradation. Importantly, pharmacological activation of CSNK1A1 using SSTC3 markedly repressed the systemic autoinflammatory responses in the trex1-/- mouse autoimmune disease model and effectively suppressed the production of IFNs and ISGs in the PBMCs of SLE patients. Taken together, our study reveals a novel regulatory role of CSNK1A1 in the autophagic degradation of STING1 to maintain immune homeostasis. Manipulating CSNK1A1 through SSTC3 might be a potential therapeutic strategy for alleviating STING1-mediated aberrant type I IFNs in autoimmune diseases.Abbreviations: BMDMs: bone marrow-derived macrophages; cGAMP: cyclic GMP-AMP; CGAS: cyclic GMP-AMP synthase; HTDNA: herring testes DNA; IFIT1: interferon induced protein with tetratricopeptide repeats 1; IFNA4: interferon alpha 4; IFNB: interferon beta; IRF3: interferon regulatory factor 3; ISD: interferon stimulatory DNA; ISGs: IFN-stimulated genes; MEFs: mouse embryonic fibroblasts; PBMCs: peripheral blood mononuclear cells; RSAD2: radical S-adenosyl methionine domain containing 2; SLE: systemic lupus erythematosus; STING1: stimulator of interferon response cGAMP interactor 1; TBK1: TANK binding kinase 1.

Exploring the role of LIAS-related cuproptosis in systemic lupus erythematosus

BACKGROUND

Cuproptosis is a novel mode of cell death, which is strongly related to energy metabolism in mitochondria and regulated by protein lipoylation. Currently, the molecular mechanisms of cuproptosis-related genes (CRGs) involved in systemic lupus erythematosus (SLE) largely remained unclear, our study is aimed to explore the mechanisms of cuproptosis and CRGs involved in SLE.

METHODS

Bulk RNA-seq datasets were collected to display the expressions of CRGs in peripheral blood mononuclear cells (PBMCs) of SLE and healthy individuals, and then ROC analysis was used to establish the diagnostic models of CRGs. Next, the immune infiltration analyses were applied to reveal the difference of immune cells infiltration in LIAS-low and LIAS-high group. Additionally, WGCNA analysis was performed to find the gene modules significantly correlated with the LIAS expression level. We also performed the functional enrichment analyses for LIAS-related gene modules to determine the potential pathways involved in the development of SLE. Finally, scRNA-seq dataset was used to cluster immune cell subsets, reveal the activated pathways, and study cell-cell interactions in LIAS-low and LIAS-high cells.

RESULT

We found CDKN2A was significantly increased and LIAS was significantly decreased in SLE patients compared with healthy individuals. The AUC score showed that LIAS had a great diagnostic value than other CRGs. Additionally, the results of immune infiltration analyses showed that immune cells proportion were diverse in LIAS-low and LIAS-high samples. The gene sets related to LIAS expression level were involved in dephosphorylation of JAK1 by SHP1, phosphorylation of STAT2, cytokine signaling in immune system, expression of interferon-alpha and beta, inhibition of JAK kinase activity by SOCS1/3, and so on. Finally, the results of cell-cell communication showed that CCL- (CCL5 + CCR1) and ANNEXIN- (ANXA1 + FPR1) might play an essential role in the communication network between LIAS-low and LIAS-high cells.

CONCLUSION

Above findings inferred that LIAS-mediated cuproptosis might involve in a comprehensive cellular and molecular mechanism to cause the occurrence and development of SLE.

Modes and Mechanisms of Salivary Gland Epithelial Cell Death in Sjogren's Syndrome

Sjogren's syndrome is an autoimmune disease in middle and old-aged women with a dry mucosal surface, which is caused by the dysfunction of secretory glands, such as the oral cavity, eyeballs, and pharynx. Pathologically, Sjogren's syndrome are characterized by lymphocyte infiltration into the exocrine glands and epithelial cell destruction caused by autoantibodies Ro/SSA and La/SSB. At present, the exact pathogenesis of Sjogren's syndrome is unclear. Evidence suggests epithelial cell death and the subsequent dysfunction of salivary glands as the main causes of xerostomia. This review summarizes the modes of salivary gland epithelial cell death and their role in Sjogren's syndrome progression. The molecular mechanisms involved in salivary gland epithelial cell death during Sjogren's syndrome as potential leads to treating the disease are also discussed.

Molecular characterization of PANoptosis-related genes with features of immune dysregulation in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease. PANoptosis is a novel form of programmed cell death involved in various inflammatory diseases. This study aimed to identify the differentially-expressed PANoptosis-related genes (PRGs) involved in immune dysregulation in SLE. Five key PRGs, including ZBP1, MEFV, LCN2, IFI27, and HSP90AB1, were identified. The prediction model with these 5 key PRGs showed a good diagnostic performance in distinguishing SLE patients from controls. These key PRGs were associated with memory B cells, neutrophils and CD8 + T cells. Besides, these key PRGs were significantly enriched in pathways involving the type I interferon responses and IL-6-JAK-STAT3 signaling. The expression levels of the key PRGs were validated in peripheral blood mononuclear cells (PBMCs) of patients with SLE. Our findings suggest that PANoptosis may be implicated in the immune dysregulation in SLE by regulating the interferons and JAK-STAT signaling pathways in memory B cells, neutrophils and CD8 + T cells.

Insights into the pathogenic role of neutrophils in systemic lupus erythematosus

PURPOSE OF REVIEW

Although dysregulated adaptive immune response has been considered as the main culprit for systemic lupus erythematosus (SLE), emerging studies have indicated that innate immunity, functioning upstream of adaptive immunity, acts as an important trigger of autoimmune diseases and promotes SLE development. Here, we have reviewed the most recent findings to highlight the influence of neutrophils on SLE pathogenesis.

RECENT FINDINGS

Neutrophils participate in SLE development mainly via promoting self-antigen exposure and autoantibody production, advocating the release of type I interferons (IFNs) and other pro-inflammatory cytokines, and mediating systemic tissue injury. A recent study revealed that neutrophil ferroptosis exerts a strong pathogenic effect in SLE, and that dysregulated innate immunity is adequate to disrupt the homeostasis of immune tolerance.

SUMMARY

Insights into the pathogenic role of neutrophils in SLE will contribute to a more comprehensive understanding of this disease and may propose novel clinical targets for accurate diagnosis and precision medicine.

Dioscin ameliorates silica-aggravated systemic lupus erythematosus via suppressing apoptosis and improving LC3-associated phagocytosis in MRL/lpr mice

Inhalation of silica not only directly leads to silicosis locally, but also results in various types of autoimmune diseases systemically, most commonly systemic lupus erythematosus (SLE). Little is known about the etiopathogenesis of silica-aggravated SLE to date, however, abnormal apoptosis and impaired apoptotic clearance have been reported to be closely related to the occurrence of SLE. LC3-associated phagocytosis (LAP) is a non-canonical form of autophagy, which plays a crucial role in mediating the clearance of apoptotic cells. Here we showed that the excessive accumulation of apoptotic debris in MRL/lpr mice exposed to silica might be due to the increased cell apoptosis and defective LAP caused by silica, thus accelerating the occurrence and progression of silica-aggravated SLE. Dioscin is an active ingredient in the family of Dioscoreaceae and is reported to possess multiple pharmacological activities, including anti-inflammatory, anti-apoptotic and autophagy-promoting properties. However, its role in SLE aggravated by silica exposure has not been investigated. In our study, we confirmed that dioscin decreased the accumulation of apoptotic debris by suppressing the excessive cell apoptosis and improving the LAP of immune cells in lung and spleen, leading to subsequent dramatically ameliorated lupus-like symptoms in silica-exposed MRL/lpr mice.