Reprogramming Macrophage Metabolism and its Effect on NLRP3 Inflammasome Activation in Sepsis

Shear-Thinning Hydrogel for Delayed Delivery of a Small Molecule Metalloproteinase Inhibitor Attenuates Myocardial Infarction Remodeling

Strategic delivery of hydrogels to the newly formed myocardial infarction (MI) is an area of active investigation and offers high target specificity for releasing a small molecule therapeutic payload. This study examined the effects of delayed post-MI delivery (pigs, 3 days post-MI) of a shear-thinning hydrogel which encapsulated and released a small molecule matrix metalloproteinase inhibitor. The results demonstrated the feasibility and efficacy of targeted delivery of a shear-thinning injectable hydrogel containing a small molecule matrix metalloproteinase inhibitor to attenuate post-MI remodeling.

Jing Si Herbal Tea Modulates Macrophage Polarization and Inflammatory Signaling in LPS-Induced Inflammation

Background: Sepsis is a lethal disease due to uncontrolled inflammatory responses. Macrophages play an important role in sepsis-associated inflammation. Jing Si Herbal Tea (JSHT) is a plant-based regimen with anti-inflammatory properties designed to treat respiratory diseases; however, its underlying therapeutic mechanism remains unclear. This study aimed to investigate the effects of JSHT on macrophage polarization and inflammatory signaling in lipopolysaccharide (LPS)-induced inflammation to provide therapeutic approaches for inflammatory diseases. Methods: RAW264.7 cells were stimulated with LPS (1 µg/mL for 16 h) to induce inflammatory responses and treated by JSHT (0.0125% concentration for 4 h) in the experimental groups (Control, JSHT, LPS, Pre-JSHT, and Post-JSHT groups). We investigated the protein and cytokine expression levels using western blotting and enzyme-linked immunosorbent assay (ELISA). Macrophage morphology was observed using immunofluorescence staining. The polarization surface markers were detected by flow cytometry. Results: In the LPS group, the expressions of the inflammatory signaling (pERK, pJNK, and nuclear NFκB) and the pro-inflammatory cytokine levels (TNF-α, IL-1β, and IL-6) were significantly increased, with M1 polarization (CD68+/CD80+) compared to the Control group. In the Pre-JSHT and Post-JSHT groups, the expressions of the inflammatory signaling and the pro-inflammatory cytokine levels were significantly decreased, with a higher M2 polarization ratio (CD163+/CD206+) compared to the LPS group. RAW264.7 cells exhibited filopodia protruding from the cell surface in the LPS group, which were inhibited in the Pre-JSHT and Post-JSHT groups. Conclusions: LPS induced M1 polarization with elevated inflammatory signaling and cytokine levels, while JSHT not only decreased M1 polarization but also promoted M2 polarization with decreased inflammatory responses. We propose JSHT as a potential anti-inflammatory agent against LPS-induced inflammation.

Development of macrophage-associated genes prognostic signature predicts clinical outcome and immune infiltration for sepsis

Sepsis is a major global health problem, causing a significant burden of disease and death worldwide. Risk stratification of sepsis patients, identification of severe patients and timely initiation of treatment can effectively improve the prognosis of sepsis patients. We procured gene expression datasets for sepsis (GSE54514, GSE65682, GSE95233) from the Gene Expression Omnibus and performed normalization to mitigate batch effects. Subsequently, we applied weighted gene co-expression network analysis to categorize genes into modules that exhibit correlation with macrophage activity. To pinpoint macrophage-associated genes (MAAGs), we executed differential expression analysis and single sample gene set enrichment analysis. We then established a prognostic model derived from four MAAGs that were significantly differentially expressed. Functional enrichment analysis and immune infiltration assessments were instrumental in deciphering the biological mechanisms involved. Furthermore, we employed principal component analysis and conducted survival outcome analyses to delineate molecular subgroups within sepsis. Four novel MAAGs-CD160, CX3CR1, DENND2D, and FAM43A-were validated and used to create a prognostic model. Subgroup classification revealed distinct molecular profiles and a correlation with 28-day survival outcomes. The MAAGs risk score was developed through univariate Cox, LASSO, and multivariate Cox analyses to predict patient prognosis. Validation of the risk score upheld its prognostic significance. Functional enrichment implicated ribonucleoprotein complex biogenesis, mitochondrial matrix, and transcription coregulator activity in sepsis, with an immune infiltration analysis indicating an association between MAAGs risk score and immune cell populations. The four MAAGs exhibited strong diagnostic capabilities for sepsis. The research successfully developed a MAAG-based prognostic model for sepsis, demonstrating that such genes can significantly stratify risk and reflect immune status. Although in-depth mechanistic studies are needed, these findings propose novel targets for therapy and provide a foundation for future precise clinical sepsis management.

Polymeric Particle BAM15 Targeting Macrophages Attenuates the Severity of LPS-Induced Sepsis: A Proof of Concept for Specific Immune Cell-Targeted Therapy

Macrophage polarization requires different energy sources and metabolic processes. Therefore, cell energy interference to alter macrophage functions has been proposed as a treatment for severe inflammatory diseases, including sepsis. In this study, targeting cell energy using BAM15 (a mitochondrial uncoupling agent) in human THP-1 and mouse RAW264.7 macrophages prominently interfered with M1 but not M2 polarization. Free BAM15 (BAM15) and BAM15-loaded PLGA particles (BAM15 particles) reduced the inflammatory response of M1 macrophages and enhanced the expression of M2 signature genes with the restoration of mitochondrial activity (extracellular flux analysis) in RAW264.7 cells. Furthermore, BAM15 particles but not BAM15 showed specific effects on the inflammatory response of macrophages but not neutrophils, and the particles were actively captured by splenic and liver macrophages in vivo. Administration of BAM15 and BAM15 particles attenuated the severity of sepsis in LPS-induced sepsis mice. Interestingly, BAM15 particles but not BAM15 alleviated LPS-induced liver injury by reducing hepatic inflammation. Our findings substantiate the superior efficacy of macrophage-targeted therapy using a BAM15 particle-delivery system and provide further support for clinical development as a potential therapy for severe inflammatory diseases.

Kurarinone exerts anti-inflammatory effect via reducing ROS production, suppressing NLRP3 inflammasome, and protecting against LPS-induced sepsis

Kurarinone, a major lavandulyl flavanone found in the roots of Sophora flavescens aiton, has been reported to exhibit anti-inflammatory and anti-oxidative activities in lipopolysaccharide (LPS)-induced macrophages; however, the effects of kurarinone on the activation of NLRP3 inflammasome and the protective effects against sepsis have not been well investigated. In this study, we aimed to investigate the impacts of kurarinone on NLRP3 inflammasome activation in lipopolysaccharide (LPS)-induced macrophages and its protective effects against sepsis in vivo. Secretion of pro-inflammatory cytokines, activation of MAPKs and NF-κB signaling pathways, formation of NLRP3 inflammasome, and production of reactive oxygen species (ROS) by LPS-induced macrophages were examined; additionally, in vivo LPS-induced endotoxemia model was used to investigate the protective effects of kurarinone in sepsis-induced damages. Our experimental results demonstrated that kurarinone inhibited the expression of iNOS and COX-2, suppressed the phosphorylation of MAPKs, attenuated the production of TNF-α, IL-6, nitric oxide (NO) and ROS, repressed the activation of the NLRP3 inflammasome, and impeded the maturation and secretion of IL-1β and caspase-1. Furthermore, the administration of kurarinone attenuated the infiltration of neutrophils in the lung, kidneys and liver, reduced the expression of organ damage markers, and increased the survival rate in LPS-challenged mice. Collectively, our study demonstrated that kurarinone can protect against LPS-induced sepsis damage and exert anti-inflammatory effects via inhibiting MAPK/NF-κB pathways, attenuating NLRP3 inflammasome formation, and preventing intracellular ROS accumulation, suggesting that kurarinone might have potential for treating sepsis and inflammation-related diseases.

Role of Macrophage lncRNAs in Mediating Inflammatory Processes in Atherosclerosis and Sepsis

Long noncoding RNAs (lncRNAs) are molecules >200 bases in length without protein-coding functions implicated in signal transduction and gene expression regulation via interaction with proteins or RNAs, exhibiting various functions. The expression of lncRNAs has been detected in many cell types, including macrophages, a type of immune cell involved in acute and chronic inflammation, removal of dead or damaged cells, and tissue repair. Increasing evidence indicates that lncRNAs play essential roles in macrophage functions and disease development. Additionally, many animal studies have reported that blockage or modulation of lncRNA functions alleviates disease severity or morbidity rate. The present review summarizes the current knowledge regarding lncRNAs expressed in macrophages, focusing on their molecular targets and the biological processes regulated by them during the development of inflammatory diseases such as atherosclerosis and sepsis. Possible application of this information to lncRNA-targeting therapy is also discussed. The studies regarding macrophage lncRNAs described in this review can help provide valuable information for developing treatments for various pathological conditions involving macrophages.

α-Hederin regulates macrophage polarization to relieve sepsis-induced lung and liver injuries in mice

Sepsis is one of the most fatal inflammatory diseases with multiple organ failure caused by pathological infection. α-Hederin, a monodesmosidic triterpenoid saponin, has many biological activities including anti-inflammation. This study aimed to investigate the effect of α-Hederin on lung and liver injuries in septic mice. Mice underwent cecal ligation and puncture-induced sepsis were intraperitoneally injected with 0.3 or 3 mg/kg α-Hederin. α-Hederin treatment dose-dependently attenuated the lung and liver injuries in septic mice. Correspondingly, α-Hederin significantly decreased malondialdehyde production, increased the levels of superoxide dismutase and glutathione in lung tissues, reduced serum alanine aminotransferase and aspartate aminotransferase activities, and suppressed the levels of TNF-α and IL-6 in both tissues and in the serum. Moreover, α-Hederin augmented CD206 level and inhibited the productions of CD86 and iNOS in lung and liver tissues of septic mice. Importantly, p-p65/p65 was suppressed, whereas IκB was elevated by α-Hederin. In conclusion, α-Hederin could improve the lung and liver injuries in mice with sepsis by regulating macrophage M1/M2 polarization and inhibiting the activation of NF-κB signaling pathway.

Prim-O-glucosycimifugin attenuates liver injury in septic mice by inhibiting NLRP3 inflammasome/caspase-1 signaling cascades in macrophages

BACKGROUND

Liver dysfunction and liver failure are serious complications of sepsis, directly leading to septic progression and death. Now, there is no specific therapeutics available for sepsis-related liver dysfunction. Prim-O-glucosylcimifugin (POG), a chromone richest in the roots of Saposhnikovia divaricata (Turcz.) Schischk, is usually used to treat headache, rheumatoid arthritis and tetanus. While, the underlying mechanisms of POG against sepsis-induced liver damage and dysfunction are still not clear.

PURPOSE

To study the anti-sepsis effect of POG, and its pharmacological mechanism to protect liver injury by weakening the function of macrophages in septic livers through inhibiting NOD-like receptor protein 3 (NLRP3) inflammasome pathway.

METHOD

In vivo experiments, septic mouse model was induced by cecal ligation and puncture (CLP), and then the mortality was detected, liver inflammatory damages and plasma biomarkers of liver injury were evaluated by histopathological staining and biochemical assays, respectively. In vitro experiments, mouse primary peritoneal macrophages were treated with lipopolysaccharide (LPS) and ATP, and then the activated-inflammasomes, macrophage migration and polarization were detected by ASC immunofluorescence staining, transwell and flow cytometry assays, respectively. NLRP3 inflammasome components NLRP3, caspase-1, IL-1β and IL-18 protein expressions were detected using western blot assays, and the contents of IL-1β and IL-18 were measured by ELISA assays.

RESULTS

POG treatment significantly decreased the mortality, liver inflammatory damages, hepatocyte apoptosis and plasma biomarkers of liver injury in CLP-challenged male WT mice, which were comparable to those in ibuprofen (a putative anti-inflammatory drug)-supplemented septic male WT mice and septic NLRP3 deficient-male mice. POG supplementation significantly suppressed NLRP3 inflammasome activation in septic liver tissues and cultured macrophages, by significantly reducing NLRP3, cleaved-caspase-1, IL-1β and IL-18 levels, the activated-inflammasome ASC specks, and macrophage infiltration and migration, as well as M1-like polarization, but significantly increasing M2-like polarization. These findings were similar to the pharmacological effects of ibuprofen, NLRP3 deficiency, and a special NLRP3 inhibitor, MCC950.

CONCLUSION

POG protected against sepsis by inhibiting NLRP3 inflammasome-mediated macrophage activation in septic liver and attenuating liver inflammatory injury, indicating that it may be a potential anti-sepsis drug candidate.