The role of ferroptosis in ischemic stroke has been hotly debated recently, but the mechanism is not clearly clarified. It has been reported that the NLRP3 inflammasome is essential for the progression of ischemic stroke. Whether the ferroptosis after ischemic stroke mediated by the activation of NLRP3 inflammasome is still not reported. In this study, we investigated the effect of NLRP3 deficiency on ferroptosis following cerebral ischemia-reperfusion injury (CIRI) in vivo and in vitro. In vivo, we used C57BL/6J mice and NLRP3^-/- mice to establish a model of middle cerebral artery occlusion (MCAO). After 3 days of reperfusion, we assessed neurological function and then performed TTC staining to measure the infarct volume. Besides, we measured the expression of NLRP3 inflammasome-related proteins and the ferroptosis-inhibiting protein glutathione peroxidase 4 (GPX4) by western blotting (WB) and immunofluorescence (IF). Moreover, we evaluated the levels of ferroptosis-related factors (Fe²⁺, MDA and GSH) in the infarct area by using appropriate kits. Furthermore, we used WB to measure the expression of Kelch-like epichlorohydrin-associated protein 1 (Keap1) and nuclear factor erythroid 2-related factor 2 (Nrf2), which participate in the progression of ischemic stroke. In vitro, we knocked down NLRP3 with small interfering RNAs (siRNAs) and established an oxygen glucose deprivation/Reperfusion (OGD/R) model in BV2 cells to simulate ischemic conditions. Next, we assessed the viability of BV2 cells by the Cell Counting Kit (CCK)-8 cytotoxicity assay. Moreover, we used WB to measure the expression of NLRP3, IL-1β, GPX4, Keap1 and Nrf2 proteins which are involved in CIRI. Three days after MCAO, the NLRP3^-/- mice exhibited smaller cerebral infarct volumes and lower neurological deficit scores. The expression of NLRP3 inflammasome-associated proteins (IL-18 and IL-1β) and Keap1/Nrf2 signaling pathway moleculars (Keap1 and Nrf2) in mice brain tissue and BV2 cells were inhibited by NLRP3 knockout/knockdown, while the expression of GPX4, one of the ferroptosis-related factors was increased. Furthermore, the contents of Fe²⁺ and MDA in the brain tissues of NLRP3^-/- mice were decreased, while the content of GSH were increased significantly. Inhibition of the NLRP3 inflammasome alleviates CIRI by inhibiting ferroptosis and inflammation, possibly through a mechanism of the Keap1-Nrf2 pathway.

Background: Sepsis-induced organ failure and high mortality are largely ascribed to the failure of bacterial clearance from the infected tissues. Recently, probiotic bacteria-released extracellular vesicles (BEVs) have been implicated as critical mediators of intercellular communication which are widely involved in the regulation of the inflammatory response. However, their functional role in macrophage phagocytosis during sepsis has never been explored. Methods: BEVs were collected from three different strains of probiotics including Lactiplantibacillus plantarum WCFS1 (LP WCFS1), Lactobacillus rhamnosus Gorbach-Goldin (LGG), and Escherichia coli Nissle 1917 (EcN), or from LGG cultured under three pH conditions (pH5-acid, pH6.5-standard, pH8-akaline) through differential centrifugation, filtration, and ultracentrifugation of their culture supernatants. In vitro phagocytosis was measured in Raw264.7 cells and bone marrow-derived macrophages using pHrodo red E. coli BioParticles. The in vivo therapeutic effects of BEVs were tested using a feces-injection-in-peritoneum (FIP) model of polymicrobial sepsis. Results: LGG-derived EVs (BEV^LGG) were the best among these three probiotics BEVs in stimulating macrophages to take up bacteria. Furthermore, BEV^LGG collected from pH8 culture condition (BEV^pH8) exhibited the strongest capacity of phagocytosis, compared with BEV^pH5 and BEV^pH6.5. Treatment of septic mice with BEV^pH8 significantly prolonged animal survival; increased bacterial clearance from the blood, peritoneal lavage fluid, and multiple organs; and decreased serum levels of pro-inflammatory cytokines/chemokines, as well as reduced multiple organ injuries, in comparison with control-treated septic mice. Mechanistically, RNA-seq and bioinformatic analysis identified that the FPR1/2 signaling was remarkably activated, along with its downstream pathways (PI3K-Akt-MARCO and NADPH-ROS) in BEV^pH8-treated macrophages, compared with control cells. Accordingly, pre-addition of Boc2, a specific antagonist of FPR1/FPR2, to macrophages significantly attenuated BEV^pH8-mediated phagocytosis, compared to controls. Conclusions: This study demonstrates that LGG-derived BEVs may have therapeutic effects against sepsis-induced organ injury and mortality through enhancing FPR1/2-mediated macrophage phagocytosis.

Sepsis is a severe systemic inflammatory syndrome characterized by a dysregulated immune response to infection, often leading to high mortality rates. The intestine, owing to its distinct structure and physiological environment, plays a pivotal role in the pathophysiology of sepsis. It functions as the “central organ” or “engine” in the progression of sepsis, with intestinal injury exacerbating the condition. Despite the availability of current therapies that offer partial symptom relief, they fall short of adequately protecting the intestinal barrier. In this study, an advanced nanodrug formulation (OLA@MΦ NPs) is developed by coating macrophage membranes onto polymeric organic nanoparticles encapsulating olaparib. When loaded into pH‐responsive capsules, an intestine‐decipher engineered capsule (cp‐OLA@MΦ NPs) is successfully formulated. Upon oral administration in septic mice, these capsules withstand gastric acid and release their contents in the intestine, specifically targeting injured tissues. The released OLA@MΦ NPs effectively neutralize pro‐inflammatory cytokines via macrophage membrane receptors, while olaparib inhibits intestinal epithelial parthanatos (a form of programmed cell death) by suppressing poly(ADP‐ribose) polymerase 1 (PARP1) activation. This strategy significantly reduces bacterial translocation, slows the progression of sepsis, and enhances survival in septic mice, thus presenting a promising therapeutic approach for sepsis in clinical applications.

Polyamines, characterized by their polycationic nature, are ubiquitously present in all organisms and play numerous cellular functions. Among polyamines, spermidine stands out as the predominant type in both prokaryotic and eukaryotic cells. The PotD-PotABC protein complex in Escherichia coli , belonging to the adenosine triphosphate–binding cassette transporter family, is a spermidine-preferential uptake system. Here, we report structural details of the polyamine uptake system PotD-PotABC in various states. Our analyses reveal distinct “inward-facing” and “outward-facing” conformations of the PotD-PotABC transporter, as well as conformational changes in the “gating” residues (F222, Y223, D226, and K241 in PotB; Y219 and K223 in PotC) controlling spermidine uptake. Therefore, our structural analysis provides insights into how the PotD-PotABC importer recognizes the substrate-binding protein PotD and elucidates molecular insights into the spermidine uptake mechanism of bacteria.

Sepsis refers to a complex syndrome associated with physiological, pathological, and biochemical abnormalities resulted from infection. Sepsis is the major cause of acute respiratory distress syndrome (ARDS). Extracellular vesicles (EVs) are serving as new messengers to mediate cell-cell communication in vivo. Non-coding RNAs, proteins and metabolites encapsulated by EVs could result in either pro-inflammatory or anti-inflammatory effects in the recipient cells. Pathogens or host cells derived EVs play an important role in pathogens infection during the occurrence and development of sepsis and ARDS. Additionally, we summarize the potential application for EVs in diagnosis, prevention and treatment for sepsis and ARDS.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), the prime causes of morbidity and mortality in critically ill patients, are usually treated by general supportive treatments. Endoplasmic reticulum autophagy (ER-phagy) maintains cellular homeostasis by degrading damaged endoplasmic reticulum (ER) fragments and misfolded proteins. ER-phagy is crucial for maintaining ER homeostasis and improving the internal environment. ER-phagy has a particular role in some aspects, such as immunity, inflammation, cell death, pathogen infection, and collagen quality. In this review, we summarized the definition, epidemiology, and pathophysiology of ALI/ARDS and described the regulatory mechanisms and functions of ER-phagy as well as discussed the potential role of ER-phagy in ALI/ARDS from the perspectives of immunity, inflammation, apoptosis, pathogen infection, and fibrosis to provide a novel and effective target for improving the prognosis of ALI/ARDS.