The Emerging Role of Ferroptosis in Sepsis, Opportunity or Challenge?

Integrative bioinformatics analysis reveals CGAS as a ferroptosis-related signature gene in sepsis and screens the potential natural inhibitors of CGAS

Sepsis is a fatal organ dysfunction characterized by the simultaneous hyperinflammation and immunosuppression. Nowadays, the early precision intervention of sepsis is challenging. Ferroptosis is involved in the development of sepsis. The current study aimed to find out the signature genes of sepsis with network topology analysis and machine learning, and further provide the potential natural compounds for sepsis with virtual screening and in vitro validation. In this study, five genes namely CGAS, DPP4, MAPK14, PPARG and TXN were identified as ferroptosis-related signature genes for sepsis by network topological analysis, machine learning algorithms, and external datasets verification. The results of immune infiltration analysis confirmed these genes were significantly associated with the infiltration abundance of some immune cells including neutrophil, macrophage, plasmacytoid dendritic cell and activated dendritic cell. Moreover, coniferin, 5-O-caffeoylshikimic acid, and psoralenoside were initially identified as the natural inhibitors of CGAS by virtual screening. However, further in vitro study on macrophages revealed coniferin and psoralenoside had better inhibitory activities on CGAS. In summary, the present study pointed out the importance of CGAS in sepsis, and discovered novel natural inhibitors of CGAS.

Targeting ferroptosis offers therapy choice in sepsis-associated acute lung injury

Sepsis-associated acute lung injury (SALI) is a common complication of sepsis, consisting of a dysfunctional host response to infection-mediated heterogenous complexes. SALI is reported in up to 50 % of patients with sepsis and causes poor outcomes. Despite high incidence, there is a lack of understanding in its pathogenesis and optimal treatment. A better understanding of the molecular mechanisms underlying SALI may help produce better therapeutics. The effects of altered cell-death mechanisms, such as non-apoptotic regulated cell death (RCD) (i.e., ferroptosis), on the development of SALI are beginning to be discovered, while targeting ferroptosis as a meaningful target in SALI is increasingly being recognized. Here, we outline how a susceptible lung alveoli may develop SALI. Then we discuss the general mechanisms underlying ferroptosis, and how it contributes to SALI. We then outline the chemical structures of the emerging agents or compounds that can protect against SALI by inhibiting ferroptosis, summarizing their potential pharmacological effects. Finally, we highlight key limitations and possible strategies to overcome them. This review suggests that a detailed mechanistic and biological understanding of ferroptosis can foster the development of pharmacological antagonists in the treatment of SALI.

The Emerging Scenario of Ferroptosis in Pancreatic Cancer Tumorigenesis and Treatment

Pancreatic cancer remains one of the most lethal forms of cancer. Currently, there is a lack of effective drug treatments for pancreatic cancer. However, as a newly discovered form of non-apoptotic cell death, ferroptosis has garnered increasing attention in relation to pancreatic cancer. Understanding the role of ferroptosis in the tumorigenesis and treatment of pancreatic cancer may enable more effective clinical trials and treatments for pancreatic cancer and may minimize side effects or restrict the emergence of drug resistance. In this review, we summarize the current knowledge regarding the process and underlying mechanisms of ferroptosis, as well as its dual role in both promoting tumorigenesis and facilitating treatment strategies for pancreatic cancer. Additionally, how ferroptosis is implicated in the development of pancreatitis and insulin resistance, indicating that ferroptosis may play an important role in the risk of pancreatitis- and insulin-resistance-related pancreatic cancers, is also addressed.

Oxidative/Nitrosative Stress and Brain Involvement in Sepsis: A Relationship Supported by Immunohistochemistry

Background and Objectives: A large amount of recent evidence suggests that cellular inability to consume oxygen could play a notable part in promoting sepsis as a consequence of mitochondrial dysfunction and oxidative stress. The latter could, in fact, represent a fundamental stage in the evolution of the "natural history" of sepsis. Following a study previously conducted by the same working group on heart samples, the present research project aims to evaluate, through an immunohistochemical study, the existence and/or extent of oxidative stress in the brains of subjects who died due to sepsis and define, after reviewing the literature, its contribution to the septic process to support the use of medications aimed at correcting redox anomalies in the management of septic patients. Materials and Methods: 10 cases of subjects who died in healthcare facilities with ante-mortem clinical-laboratory signs that allowed the diagnosis of septic shock were selected as case studies, and 1 case of a subject who died immediately following a road traffic accident was used as a negative control. Samples of the cerebral cortex were then taken, fixed in formalin, and subjected to sections on which an immunohistochemical study was performed using anti-NOX-2, NT, iNOS, and 8-OHdG antibodies. Results: The results emerging from the present study demonstrate that despite a variable expressivity for the NT, iNOS, and NOX2 markers, the brain samples demonstrated univocal and high positivity for the 8-OHdG marker. Conclusions: This would allow us to hypothesize how, regardless of the mechanism of production of ROS and NOS (iNOS or NOX2 mediated) and the pathophysiological mechanisms that are triggered during sepsis, oxidative damage to DNA represents the event to which this whole process leads and, in fact, in the literature, is directly correlated to sepsis-dependent mortality. Neurons, conversely, appear to be more sensitive to oxidative stress because of a low number of protective or scavenger molecules (catalase, glutathione peroxidase, GSH, or vitamin E). Therefore, despite reduced production, the manifestation of the damage remains high. This evidence, together with that of the previous study, can only support the introduction of substances with an antioxidant function in the guidelines for the treatment of sepsis.

Ablation of mitophagy receptor FUNDC1 accentuates septic cardiomyopathy through ACSL4-dependent regulation of ferroptosis and mitochondrial integrity

Sepsis evokes compromised myocardial function prompting heart failure albeit target therapy remains dismal. Our study examined the possible role of mitophagy receptor FUNDC1 in septic cardiomyopathy. A sepsis model was established using cecal ligation and puncture (CLP) in FUNDC1 knockout (FUNDC1-/-) and WT mice prior to the evaluation of cardiac morphology, echocardiographic and cardiomyocyte contractile, oxidative stress, apoptosis, necroptosis, and ferroptosis. RNAseq analysis depicted discrepant patterns in mitophagy, oxidative stress and ferroptosis between CLP-challenged and control murine hearts. Septic patients displayed cardiac injury alongside low plasma FUNDC1 and iron levels. CLP evoked interstitial fibrosis, cardiac dysfunction (lowered ejection fraction, fractional shortening, shortening/relengthening velocity, peak shortening and electrically-stimulated intracellular Ca2+ rise, alongside increased LV end systolic diameter and relengthening duration), O2- buildup, apoptosis, necroptosis, and ferroptosis (downregulated GPX4 and SLC7A11), the responses of which were accentuated by FUNDC1 ablation. In particular, levels of lipid peroxidation enzyme acyl-CoA synthetase long-chain family member 4 (ACSL4) were upregulated following CLP procedure, with a more pronounced response in FUNDC1-/- mice. Co-immunoprecipitation and interaction interface revealed an evident interaction between FUNDC1 and ACSL4. In vitro studies revealed that the endotoxin lipopolysaccharide provoked cardiomyocyte contractile and lipid peroxidation anomalies, the responses were reversed by the mitophagy inducer oleanolic acid, inhibition of ACSL4 and ferroptosis. These findings favor a role for FUNDC1-ACSL4-ferroptosis cascade in septic cardiomyopathy.

Epigenetic mechanism of EZH2-mediated histone methylation modification in regulating ferroptosis of alveolar epithelial cells in sepsis-induced acute lung injury

Sepsis-induced acute lung injury (SI-ALI) leads to significant deaths in critically ill patients worldwide. This study explores the mechanism of EZH2 regulating ferroptosis of alveolar epithelial cells (AECs) in SI-ALI. In vitro cell model and in vivo mouse lung injury model of sepsis were established. EZH2 expression in lung tissues was intervened by sh-EZH2, followed by H&E staining observation of lung tissue pathological changes. EZH2, H3K27me3, USP10, GPX4, and ACSL4 expressions were determined by qRT-PCR or Western blot. ROS, GSH, and iron ion levels were detected using fluorescent labeling and reagent kits, respectively. ChIP analyzed the enrichment of EZH2 and H3K27me3 on USP10 promoter. The binding between USP10 and GPX4, and the ubiquitination level of GPX4 were detected using Co-IP. EZH2 was highly expressed in lung tissues of SI-ALI mice. EZH2 silencing alleviated ALI and ferroptosis of AECs; EZH2 increased the H3K27me3 level on USP10 promoter through histone methylation. USP10 stabilized GPX4 protein expression through ubiquitination; inhibition of USP10 partially reversed the inhibitory effect of EZH2 silencing on ferroptosis of AECs. In conclusion, EZH2 depresses USP10 expression by promoting histone H3K27me3 modification on USP10 promoter, thereby enhancing ubiquitination degradation of GPX4 and ultimately facilitating ferroptosis of AECs in sepsis.

The possible mechanisms of ferroptosis in sepsis-associated acquired weakness

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection, and its morbidity and mortality rates are increasing annually. It is an independent risk factor for intensive care unit-acquired weakness (ICU-AW), which is a common complication of patients in ICU. This situation is also known as sepsis-associated acquired weakness (SAW), and it can be a complication in more than 60% of patients with sepsis. The outcomes of SAW are often prolonged mechanical ventilation, extended hospital stays, and increased morbidity and mortality of patients in ICUs. The pathogenesis of SAW is unclear, and an effective clinical treatment is not available. Ferroptosis is an iron-dependent type of cell death with unique morphological, biochemical, and genetic features. Unlike other forms of cell death such as autophagy, apoptosis, and necrosis, ferroptosis is primarily driven by lipid peroxidation. Cells undergo ferroptosis during sepsis, which further enhances the inflammatory response. This process leads to increased cell death, as well as multi-organ dysfunction and failure. Recently, there have been sporadic reports suggesting that SAW is associated with ferroptosis, but the exact pathophysiological mechanisms remain unclear. Therefore, we reviewed the possible pathogenesis of ferroptosis that leads to SAW and offer new strategies to prevent and treat SAW.

Sepsis‑induced cardiac dysfunction and pathogenetic mechanisms (Review)

Sepsis is a manifestation of the immune and inflammatory response to infection, which may lead to multi‑organ failure. Health care advances have improved outcomes in critical illness, but it still remains the leading cause of death. Septic cardiomyopathy is heart dysfunction brought on by sepsis. Septic cardiomyopathy is a common consequence of sepsis and has a mortality rate of up to 70%. There is a lack of understanding of septic cardiomyopathy pathogenesis; knowledge of its pathogenesis and the identification of potential therapeutic targets may reduce the mortality rate of patients with sepsis and lead to clinical improvements. The present review aimed to summarize advances in the pathogenesis of cardiac dysfunction in sepsis, with a focus on mitochondrial dysfunction, metabolic changes and cell death modalities and pathways. The present review summarized diagnostic criteria and outlook for sepsis treatment, with the goal of identifying appropriate treatment methods for this disease.