MCP-induced protein 1 attenuates sepsis-induced acute lung injury by modulating macrophage polarization via the JNK/c-Myc pathway

Peficitinib alleviated acute lung injury by blocking glycolysis through JAK3/STAT3 pathway

Peficitinib is a selective Janus kinase (JAK3) inhibitor recently developed and approved for the treatment of rheumatoid arthritis in Japan. Glycolysis in macrophages could induce NOD-like receptor (NLR) family and pyrin domain-containing protein 3 (NLRP3) inflammasome activation, thus resulting in pyroptosis and acute lung injury (ALI). The aim of our study was to investigate whether Peficitinib could alleviate lipopolysaccharide (LPS)-induced ALI by inhibiting NLRP3 inflammasome activation. Wild type C57BL/6J mice were intraperitoneally injected with Peficitinib (5 or 10 mg·kg-1·day-1) for 7 consecutive days before LPS injection. The results showed that Peficitinib pretreatment significantly relieved LPS-induced pulmonary edema, inflammation, and apoptosis. NLRP3 inflammasome and glycolysis in murine lung tissues challenged with LPS were also blocked by Peficitinib. Furthermore, we found that the activation of JAK3/signal transducer and activator of transcription 3 (STAT3) was also suppressed by Peficitinib in mice with ALI. However, in Jak3 knockout mice, Peficitinib did not show obvious protective effects after LPS injection. In vitro experiments further showed that Jak3 overexpression completely abolished Peficitinib-elicited inhibitory effects on pyroptosis and glycolysis in LPS-induced RAW264.7 macrophages. Finally, we unveiled that LPS-induced activation of JAK3/STAT3 was mediated by toll-like receptor 4 (TLR4) in RAW264.7 macrophages. Collectively, our study proved that Peficitinib could protect against ALI by blocking JAK3-mediated glycolysis and pyroptosis in macrophages, which may serve as a promising candidate against ALI in the future.

Identification of PIK3R5 as a hub in septic myocardial injury and the cardioprotective effects of Psoralidin

BACKGROUND

Myocardial injury is a severe complication of sepsis, resulting in substantial morbidity and mortality. Psoralidin (PSO), derived from the seeds of Psoralea corylifolia L., has garnered considerable attention due to its potent pharmacological effects, including anti-inflammatory and antibacterial effects.

PURPOSE

Our previous work conducted affirmed that PSO has a protective effect on sepsis and septic myocardial injury, however the specific molecular mechanisms need further clarification.

STUDY DESIGN

This objective of this study was to use three analytic modalities and bioinformatics methods to identify potential targets, followed by experimental verification.

METHODS

A series of experiments methods (including echocardiography, HE, western blot, qPCR, RNA-seq, network pharmacology) were used to evaluate the effects of PSO against sepsis and septic myocardial injury in cecal ligation and puncture (CLP)-injured BALB/c mice and lipopolysaccharide (LPS)-injured HL-1 cardiomyocytes.

RESULTS

Firstly, a group of sepsis-related genes were identified by integrating database surveys, RNA-seq analysis, and weighted gene co-expression network analysis (WCGNA). Subsequently, the pharmacological targets of PSO were predicted. Furthermore, the identification of phosphoinositide 3- kinase regulatory subunit 5 (PIK3R5) as a crucial hub gene was accomplished via protein-protein interaction network and molecular docking approach. In vivo experiments showed that PSO treatment alleviated septic myocardial injury, as evidenced by improved cardiac function indicators and inflammation response. Similar results were obtained in vitro experiments. Importantly, the expression of PI3KR5 was decreased in the myocardium and cardiomyocytes, and the effect was reversed by PSO treatment.

CONCLUSION

This study systematically revealed the key targets of PSO in the treatment of septic myocardial injury. These findings offer valuable insights into disease-drug targets, which have certain clinical significance to exploring disease biomarkers and potential therapeutic targets for septic patients.

Ghrelin/GHSR Axis Induced M2 Macrophage and Alleviated Intestinal Barrier Dysfunction in a Sepsis Rat Model by Inactivating E2F1/NF-κB Signaling

Sepsis is an inflammatory reaction disorder state that is induced by infection. The activation and regulation of the immune system play an essential role in the development of sepsis. Our previous studies have shown that ghrelin ameliorates intestinal dysfunction in sepsis. Very little is known about the mechanism of ghrelin and its receptor (GHSR) on the intestinal barrier and the immune function of macrophage regulation. Our research is to investigate the regulatory effect and molecular mechanism of the ghrelin/GHSR axis on intestinal dysfunction and macrophage polarization in septic rats. A rat model of sepsis was established by cecal ligation and puncture (CLP) operation. Then, the sepsis rats were treated with a ghrelin receptor agonist (TZP-101) or ghrelin inhibitor (obestatin). The results suggested that TZP-101 further enhanced ghrelin and GHSR expressions in the colon and spleen of septic rats and obestatin showed the opposite results. Ghrelin/GHSR axis ameliorated colonic structural destruction and intestinal epithelial tight junction injury in septic rats. In addition, the ghrelin/GHSR axis promoted M2-type polarization of macrophages, which was characterized by the decreases of IL-1β, IL-6, and TNF-α, as well as the increase of IL-10. Mechanistically, the ghrelin/GHSR axis promoted E2F2 expression and suppressed the activation of the NF-κB signaling pathway in septic rats. Collectively, targeting ghrelin/GHSR during sepsis may represent a novel therapeutic approach for the treatment of intestinal barrier injury.

Inhibition of focal adhesion kinase 2 results in a macrophage polarization shift to M2 which attenuates local and systemic inflammation and reduces heterotopic ossification after polysystem extremity trauma

Introduction

Heterotopic ossification (HO) is a complex pathology often observed in combat injured casualties who have sustained severe, high energy polytraumatic extremity injuries. Once HO has developed, prophylactic therapies are limited outside of surgical excision. Tourniquet-induced ischemia injury (IR) exacerbates trauma-mediated musculoskeletal tissue injury, inflammation, osteogenic progenitor cell development and HO formation. Others have shown that focal adhesion kinase-2 (FAK2) plays a key role in regulating early inflammatory signaling events. Therefore, we hypothesized that targeting FAK2 prophylactically would mitigate extremity trauma induced IR inflammation and HO formation.

Methods

We tested whether the continuous infusion of a FAK2 inhibitor (Defactinib, PF-573228; 6.94 µg/kg/min for 14 days) can mitigate ectopic bone formation (HO) using an established blast-related extremity injury model involving femoral fracture, quadriceps crush injury, three hours of tourniquet-induced limb ischemia, and hindlimb amputation through the fracture site. Tissue inflammation, infiltrating cells, osteogenic progenitor cell content were assessed at POD-7. Micro-computed tomography imaging was used to quantify mature HO at POD-56.

Results

In comparison to vehicle control-treated rats, FAK2 administration resulted in no marked wound healing complications or weight loss. FAK2 treatment decreased HO by 43%. At POD-7, marked reductions in tissue proinflammatory gene expression and assayable osteogenic progenitor cells were measured, albeit no significant changes in expression patterns of angiogenic, chondrogenic and osteogenic genes. At the same timepoint, injured tissue from FAK-treated rats had fewer infiltrating cells. Additionally, gene expression analyses of tissue infiltrating cells resulted in a more measurable shift from an M1 inflammatory to an M2 anti-inflammatory macrophage phenotype in the FAK2 inhibitor-treated group.

Discussion

Our findings suggest that FAK2 inhibition may be a novel strategy to dampen trauma-induced inflammation and attenuate HO in patients at high risk as a consequence of severe musculoskeletal polytrauma.

Salidroside ameliorated the pulmonary inflammation induced by cigarette smoke via mitigating M1 macrophage polarization by JNK/c-Jun

Pulmonary inflammation induced by cigarette smoke (CS) promoted the development of chronic obstructive pulmonary disease (COPD), and macrophage polarization caused by CS modulated inflammatory response. Previous studies indicated that salidroside exerted therapeutic effects in COPD, but the anti-inflammatory mechanisms were not clear. This study aimed to explore the effects and mechanisms of salidroside on macrophage polarization induced by CS. Wistar rats received passively CS exposure and were treated intraperitoneally with salidroside at a low, medium or high dose. Lung tissues were stained with hematoxylin-eosin. Emphysema and inflammatory scores were evaluated by histomorphology. Lung function, cytokines, and cell differential counts in BALF were detected. The macrophage polarization was determined by immunohistochemistry in lung tissues. Alveolar macrophages (AMs) were isolated and treated with cigarette smoke extract (CSE), salidroside or inhibitors of relative pathways. The polarization status was determined by qPCR, and the protein level was detected by Western blotting. CS exposure induced emphysema and lung function deterioration. The inflammatory scores, cytokines level and neutrophils counts were elevated after CS exposure. Salidroside treatment partly ameliorated above abnormal. CS exposure activated M1 and M2 polarization of AMs in vivo and in vitro, and salidroside mitigated M1 polarization induced by CS. CSE activated the JNK/c-Jun in AMs and the M1 polarization of AMs was inhibited by the inhibitors of JNK and AP-1. Salidroside treatment deactivated the JNK/c-Jun, which indicated that salidroside mitigated the M1 polarization of AMs induced by CS via inhibiting JNK/c-Jun. Salidroside treatment ameliorated the pulmonary inflammation and M1 polarization of AMs induced by CS, and the process might be mediated by the deactivation of JNK/c-Jun.

The role of macrophages polarization in sepsis-induced acute lung injury

Sepsis presents as a severe infectious disease frequently documented in clinical settings. Characterized by its systemic inflammatory response syndrome, sepsis has the potential to trigger multi-organ dysfunction and can escalate to becoming life-threatening. A common fallout from sepsis is acute lung injury (ALI), which often progresses to acute respiratory distress syndrome (ARDS). Macrophages, due to their significant role in the immune system, are receiving increased attention in clinical studies. Macrophage polarization is a process that hinges on an intricate regulatory network influenced by a myriad of signaling molecules, transcription factors, epigenetic modifications, and metabolic reprogramming. In this review, our primary focus is on the classically activated macrophages (M1-like) and alternatively activated macrophages (M2-like) as the two paramount phenotypes instrumental in sepsis' host immune response. An imbalance between M1-like and M2-like macrophages can precipitate the onset and exacerbate the progression of sepsis. This review provides a comprehensive understanding of the interplay between macrophage polarization and sepsis-induced acute lung injury (SALI) and elaborates on the intervention strategy that centers around the crucial process of macrophage polarization.

Huoluo Xiaoling Pellet promotes microglia M2 polarization through increasing MCPIP1 expression for ischemia stroke alleviation

Huoluo Xiaoling Pellet (HXP), a Chinese patent medicine, is commonly administered for the treatment of treat ischemic strokes. MCPIP1, an inducible suppressor of the inflammatory response, is a regulator of microglial M2 polarization. This study aimed to explore whether HXP can promote microglial M2 polarization by upregulating MCPIP1 expression, consequently mitigating cerebral ischemic injury. Our study involved 85 Sprague-Dawley rats (weighing 250-280 g). We established middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation-reoxygenation (OGD/R) models with MCPIP1 knockdown to assess the effects of HXP on ischemic strokes. Our findings show that HXP reduced brain water content, improved neurological function, and inhibited the expression of inflammatory factors in the brain tissues of MCAO rats. The neuroprotective effects of HXP on cerebral ischemic injuries were compromised by MCPIP1 knockdown. Immunofluorescence results indicated that the expression of microglia marker Iba1 and M2 phenotypic marker CD206 was upregulated in MCAO rats and OGD/R-treated microglia. Administration of HXP significantly reduced Iba1 expression and facilitated CD206 expression, an effect that was counteracted by sh-MCPIP1 transfection. Western blotting revealed that HXP treatment augmented the expression of MCPIP1, microglial M2 marker proteins (CD206 and Arg1), and PPARγ, while reducing the expression of microglial M1 marker proteins (CD16 and iNOS) in MCAO rats and OGD/R-induced microglia. MCPIP1 knockdown suppressed HXP-mediated upregulation of MCPIP1, CD206, Arg1, and PPARγ, as well as the downregulation of CD16 and iNOS. Our findings suggest that HXP primarily ameliorates ischemic stroke through the upregulation of MCPIP1, which in turn induces microglial M2 polarization.

Intermittent fasting attenuates lipopolysaccharide-induced acute lung injury in mice by modulating macrophage polarization

Acute lung injury (ALI) is a spectrum of acute and life-threatening pulmonary inflammatory conditions. Treatment of ALI remains a clinical challenge. Recently, intermittent fasting (IF) has been shown to improve health and alleviate many diseases. In this study, we tested whether IF attenuated ALI and investigated the mechanism underlying this process. In vivo, the effects of IF on ALI were evaluated in a lipopolysaccharide (LPS)-induced murine ALI model. We found that two times of 24-h fasting in a week before ALI efficiently ameliorated LPS-induced lung injury in mice, characterized by alleviated lung lesions, wet-to-dry weight ratio, myeloperoxidase activity, malondialdehyde content, and lower levels of tumor necrosis factor-α, interleukin-6, and interleukin-1β. In vitro, functional assays were conducted to assess IF on the inflammatory response and macrophage polarization of bone marrow-derived macrophages (BMDMs) treated with LPS or IL-4. And PPARγ antagonist GW9662 and AMPK siRNA were used to test the role of PPARγ and AMPK in the IF-mediated improvement of ALI. The results showed that IF (serum deprivation) suppressed macrophage M1 activation and promoted M2 activation in LPS-treated BMDMs. While, IF also augmented macrophage M2 polarization in IL-4-treated BMDMs. Further mechanistic studies showed that the promotive effect of IF on M2 polarization was related to the activation of the PPARγ and AMPK pathways. In conclusion, this study suggests that IF enhances M2 polarization by activating the AMPK and PPARγ pathways, thus facilitating anti-inflammatory response and ameliorating ALI.

The Sphingosine Kinase 2 Inhibitor Opaganib Protects Against Acute Kidney Injury in Mice

Introduction

Acute kidney injury (AKI) is a common multifactorial adverse effect of surgery, circulatory obstruction, sepsis or drug/toxin exposure that often results in morbidity and mortality. Sphingolipid metabolism is a critical regulator of cell survival and pathologic inflammation processes involved in AKI. Opaganib (also known as ABC294640) is a first-in-class experimental drug targeting sphingolipid metabolism that reduces the production and activity of inflammatory cytokines and, therefore, may be effective to prevent and treat AKI.

Methods

Murine models of AKI were used to assess the in vivo efficacy of opaganib including ischemia-reperfusion (IR) injury induced by either transient bilateral occlusion of renal blood flow (a moderate model) or nephrectomy followed immediately by occlusion of the contralateral kidney (a severe model) and lipopolysaccharide (LPS)-induced sepsis. Biochemical and histologic assays were used to quantify the effects of oral opaganib treatment on renal damage in these models.

Results

Opaganib suppressed the elevations of creatinine and blood urea nitrogen (BUN), as well as granulocyte infiltration into the kidneys, of mice that experienced moderate IR from transient bilateral ligation. Opaganib also markedly decreased these parameters and completely prevented mortality in the severe renal IR model. Additionally, opaganib blunted the elevations of BUN, creatinine and inflammatory cytokines following exposure to LPS.

Conclusion

The data support the hypotheses that sphingolipid metabolism is a key mediator of renal inflammatory damage following IR injury and sepsis, and that this can be suppressed by opaganib. Because opaganib has already undergone clinical testing in other diseases (cancer and Covid-19), the present studies support conducting clinical trials with this drug with surgical or septic patients at risk for AKI.

Macrophage Polarization and Reprogramming in Acute Inflammation: A Redox Perspective

Macrophage polarization refers to the process by which macrophages can produce two distinct functional phenotypes: M1 or M2. The balance between both strongly affects the progression of inflammatory disorders. Here, we review how redox signals regulate macrophage polarization and reprogramming during acute inflammation. In M1, macrophages augment NADPH oxidase isoform 2 (NOX2), inducible nitric oxide synthase (iNOS), synaptotagmin-binding cytoplasmic RNA interacting protein (SYNCRIP), and tumor necrosis factor receptor-associated factor 6 increase oxygen and nitrogen reactive species, which triggers inflammatory response, phagocytosis, and cytotoxicity. In M2, macrophages down-regulate NOX2, iNOS, SYNCRIP, and/or up-regulate arginase and superoxide dismutase type 1, counteract oxidative and nitrosative stress, and favor anti-inflammatory and tissue repair responses. M1 and M2 macrophages exhibit different metabolic profiles, which are tightly regulated by redox mechanisms. Oxidative and nitrosative stress sustain the M1 phenotype by activating glycolysis and lipid biosynthesis, but by inhibiting tricarboxylic acid cycle and oxidative phosphorylation. This metabolic profile is reversed in M2 macrophages because of changes in the redox state. Therefore, new therapies based on redox mechanisms have emerged to treat acute inflammation with positive results, which highlights the relevance of redox signaling as a master regulator of macrophage reprogramming.

IL35 attenuated LPS-induced acute lung injury by regulating macrophage polarization

BACKGROUND

Interleukin 35 (IL35) has been reported to play a role in acute lung injury (ALI); however, the current results regarding the relationship between IL35 and ALI are inconsistent. Therefore, we aimed to further determine the function of IL35 in ALI in mice and the potential mechanism in this paper.

MATERIALS AND METHODS

Hematoxylin-eosin (HE) staining and Masson staining were used to evaluate lung injury in mice. Immunohistochemical staining was used to evaluate the expression of IL35 p35, TLR4 and MD2 and the Bax/Bcl2 and p-P65/P65 ratios. The expression levels of IL35 EBi3, CD68, CD206 and MPO were assessed by immunofluorescence staining. RT-PCR was used to examine the expression levels of IL1β and IL6. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining was performed to detect apoptotic cells.

RESULTS

Overexpression of IL35 alleviated LPS-induced ALI in mice. IL35 overexpression decreased the expression of CD68 and increased the expression of CD206 in mice with ALI. Furthermore, upregulation of IL35 expression obviously reduced the expression of MPO, IL1β and IL6 in the lung tissues of mice with ALI. Mechanistically, IL35 suppressed the TLR4/NFκB-P65 pathway, leading to the promotion of the M1 to M2 macrophage transition and alleviation of inflammation in mice with ALI.

CONCLUSIONS

IL35 relieved LPS-induced inflammation and ALI in mice by regulating M1/M2 macrophage polarization and inhibiting the activation of the TLR4/NFκB-P65 pathway.

Paraquat Induces Lung Injury via miR-199-Mediated SET in a Mouse Model

Objective: To explore the molecular mechanism of lung injury caused by paraquat (PQ) poisoning by investigating miR-199-mediated SET.

Methods: A paraquat poisoning model was established in C57BL/6 male mice via intraperitoneal injection of paraquat. The mice were transfected with miR-199 siRNA and or mimic. After 14 days of treatment, pathophysiological changes of the lung were observed and lung tissue was analyzed via Hematoxylin-Eosin staining. The levels of miR-199, SETs, surfactant protein SP-A and SP-B, and inflammatory and oxidative factors were analyzed by qPCR, Western Blot, and ELISA kits.

Results: A acute lung-injury (ALI) model was established using PQ treatment and confirmed with edema of pulmonary endothelium with low electronic density of endothelial cytoplasm, presence of protein-rich fluid, and numerous erythrocytes in alveolar space, concentric figures of damaged tubular myelin, alveolar destruction, and increase in inflammatory cell numbers. Compared with the control group, miR-199 and SET levels were reduced in the PQ-treated group. miR-199 siRNA increased the SET level, inflammatory and oxidative levels, and reduced the levels of SP-A and SP-B, and miR-199 mimic reduced the SET level, inflammatory and oxidative levels, and increased the levels of SP-A and SP-B. PQ treatment reduced miR-199 level.

Conclusion: Paraquat induces ALI by affecting miR-199-mediated SET.

miR‑223 ameliorates thalamus hemorrhage‑induced central poststroke pain via targeting NLRP3 in a mouse model

Central poststroke pain (CPSP) is a central neuropathic pain syndrome that occurs following a stroke and mainly manifests as pain and paresthesia in the body region corresponding to the brain injury area. At present, due to the lack of clinical attention given to CPSP, patients suffer from long-term pain that seriously affects their quality of life. Current literature indicates that microRNA (miR)-223 can impede inflammation and prevent collateral damage. The NLR family pyrin domain containing 3 (NLRP3) inflammasome induces IL-18 and IL-1β secretion and maturation and participates in the inflammatory response. Previous evidence has confirmed that miR-223 can negatively regulate NLRP3 in the development of inflammatory responses. However, whether the miR-223 targeting of NLRP3 is involved in CPSP remains unclear. In the present study, the expression of miR-223 was detected by reverse transcription-quantitative PCR analysis. The expression levels of NLRP3, caspase-1, ASC, IL-18, IL-1β, ERK1/2, p-ERK1/2 and GFAP were detected by western blot analysis. The results demonstrated that thalamic hemorrhagic stroke triggered by microinjection of collagenase Ⅳ (Coll IV) into the ventral posterior lateral (VPL) nucleus results in pain hypersensitivity. miR-223 expression level were significantly reduced in the CPSP model. The expression levels of NLRP3, caspase-1, ASC, IL-18 and IL-1β were significantly increased in the CPSP model. The expression level of GFAP was detected to determine astrocyte activation. The results demonstrated that astrocyte activation induced by Coll IV produced a CPSP model. The p-ERK1/2 expression level was demonstrated to be significantly increased in the CPSP model. The introduction of an miR-223 agomir significantly attenuated thalamic pain and significantly decreased the levels of NLRP3, caspase-1, ASC and proinflammatory cytokines (IL-18 and IL-1β). Furthermore, introducing a miR-223 antagomir into the VPL nucleus of naïve mice mimicked thalamic pain and significantly increased the levels of NLRP3, caspase-1, ASC and proinflammatory cytokine levels (IL-18 and IL-1β). These results indicated that miR-223 inhibited NLRP3 inflammasome activity (caspase-1, NLRP3 and ASC), which ameliorated thalamus hemorrhage-induced CPSP in mice via NLRP3 downregulation. In conclusion, these results may determine the mechanisms underlying CPSP and facilitate development of targeted therapy for CPSP.

LncRNA TCONS_00145741 Knockdown Prevents Thrombin-Induced M1 Differentiation of Microglia in Intracerebral Hemorrhage by Enhancing the Interaction Between DUSP6 and JNK

Background: The differentiation of microglia from M1 to M2 exerts a pivotal role in the aggression of intracerebral hemorrhage (ICH), and long non-coding RNAs (lncRNAs) are associated with the differentiation of microglia. However, the underlying mechanism had not been fully clarified.

Methods: The expression profile of lncRNAs in thrombin-induced primary microglia was analyzed by RNA sequencing. Under thrombin treatment, the effect of lncRNA TCONS_00145741 on the differentiation of microglia was determined by immunofluorescence staining, quantitative real-time PCR, and Western blot. The potential mechanism and related signaling pathways of TCONS_00145741 in the M1 and M2 differentiation of microglia in ICH were assessed by Gene Ontology analysis, flow cytometry, RNA pull-down, RNA Immunoprecipitation, and RNA fluorescence in situ hybridization followed by immunofluorescence analysis.

Results: LncRNA TCONS_00145741 expression was elevated in the thrombin-induced primary microglia, and the interference with TCONS_00145741 restrained the M1 differentiation of microglia and facilitated the M2 differentiation under thrombin treatment. The interference with TCONS_00145741 restrained the activation of the JNK pathway in microglia under thrombin treatment and repressed the JNK phosphorylation levels by enhancing the interaction between DUSP6 and JNK. In vivo experiments further illustrated that the interference with TCONS_00145741 alleviated ICH.

Conclusion: LncRNA TCONS_00145741 knockdown prevented thrombin-induced M1 differentiation of microglia in ICH by enhancing the interaction between DUSP6 and JNK. This study might provide a promising target for the clinical treatment of ICH.

Macrophage Polarization and Its Role in Liver Disease

Macrophages are important immune cells in innate immunity, and have remarkable heterogeneity and polarization. Under pathological conditions, in addition to the resident macrophages, other macrophages are also recruited to the diseased tissues, and polarize to various phenotypes (mainly M1 and M2) under the stimulation of various factors in the microenvironment, thus playing different roles and functions. Liver diseases are hepatic pathological changes caused by a variety of pathogenic factors (viruses, alcohol, drugs, etc.), including acute liver injury, viral hepatitis, alcoholic liver disease, metabolic-associated fatty liver disease, liver fibrosis, and hepatocellular carcinoma. Recent studies have shown that macrophage polarization plays an important role in the initiation and development of liver diseases. However, because both macrophage polarization and the pathogenesis of liver diseases are complex, the role and mechanism of macrophage polarization in liver diseases need to be further clarified. Therefore, the origin of hepatic macrophages, and the phenotypes and mechanisms of macrophage polarization are reviewed first in this paper. It is found that macrophage polarization involves several molecular mechanisms, mainly including TLR4/NF-κB, JAK/STATs, TGF-β/Smads, PPARγ, Notch, and miRNA signaling pathways. In addition, this paper also expounds the role and mechanism of macrophage polarization in various liver diseases, which aims to provide references for further research of macrophage polarization in liver diseases, contributing to the therapeutic strategy of ameliorating liver diseases by modulating macrophage polarization.

LncRNA-Cox2 regulates macrophage polarization and inflammatory response through the CREB-C/EBPβ signaling pathway in septic mice

LncRNA-Cox2 has been reported to regulate macrophage polarization, and the activation of macrophages is a major participant in the pathogenesis of sepsis. Therefore, we explored whether lncRNA-Cox2 was involved in the progression of sepsis. In this study, we established a cecal ligation and puncture (CLP) mouse model and found that silencing lncRNA-Cox2 in CLP mice improved the 7-day survival rate, and alleviated the increase of blood bacterial burdens, systemic inflammatory response, and pulmonary dysfunction induced by CLP. Besides, interference with lncRNA-Cox2 declined the percentage of M1 macrophages and increased the percentage of M2 macrophages in the spleens of CLP mice. In vitro, the knockdown of lncRNA-Cox2 suppressed LPS-induced inflammation and M1 macrophage marker expression, and promoted M2 macrophage marker expression in primary peritoneal macrophages and RAW264.7 cells. Moreover, lncRNA-Cox2 induced CREB phosphorylation by binding to CREB, and increased phosphorylated-CREB enrichment in the C/EBPβ promoter region, so as to promote C/EBPβ transcription, thereby activating the CREB-C/EBPβ cascade. In addition, overexpressing lncRNA-Cox2 enhanced the effect of LPS on inflammation and macrophage polarization, which was reversed by treatment with 666-15 (an inhibitor of CREB). In conclusion, silencing lncRNA-Cox2 restrained the progression of sepsis in mice by modulating macrophage polarization and inflammatory response through suppressing CREB-C/EBPβ pathway.

Mechanosensitive cation channel Piezo1 contributes to ventilator-induced lung injury by activating RhoA/ROCK1 in rats

Background

Mechanical ventilation can induce or aggravate lung injury, which is termed ventilator-induced lung injury (VILI). Piezo1 is a key element of the mechanotransduction process and can transduce mechanical signals into biological signals by mediating Ca²⁺ influx, which in turn regulates cytoskeletal remodeling and stress alterations. We hypothesized that it plays an important role in the occurrence of VILI, and investigated the underlying mechanisms.

Methods

High tidal volume mechanical ventilation and high magnitude cyclic stretch were performed on Sprague–Dawley rats, and A549 and human pulmonary microvascular endothelial cells, respectively, to establish VILI models. Immunohistochemical staining, flow cytometry, histological examination, enzyme-linked immunosorbent assay, western blotting, quantitative real-time polymerase chain reaction and survival curves were used to assess the effect of Piezo1 on induction of lung injury, as well as the signaling pathways involved.

Results

We observed that Piezo1 expression increased in the lungs after high tidal volume mechanical ventilation and in cyclic stretch-treated cells. Mechanistically, we observed the enhanced expression of RhoA/ROCK1 in both cyclic stretch and Yoda1-treated cells, while the deficiency or inhibition of Piezo1 dramatically antagonized RhoA/ROCK1 expression. Furthermore, blockade of RhoA/ROCK1 signaling using an inhibitor did not affect Piezo1 expression. GSMTx4 was used to inhibit Piezo1, which alleviated VILI-induced pathologic changes, water content and protein leakage in the lungs, and the induction of systemic inflammatory mediators, and improved the 7-day mortality rate in the model rats.

Conclusions

These findings indicate that Piezo1 affects the development and progression of VILI through promotion of RhoA/ROCK1 signaling.

The lncRNA CCAT2 Rs6983267 G Variant Contributes to Increased Sepsis Susceptibility in a Southern Chinese Population

Purpose

Accumulating evidence demonstrates that genetic susceptibility genes can be used as biomarkers to assess sepsis susceptibility, and genetic variation is associated with susceptibility and clinical outcomes in patients with sepsis and inflammatory disease. Although studies have shown that the lncRNA CCAT2 is involved in inflammatory diseases, it remains unclear whether CCAT2 gene polymorphisms are associated with susceptibility to inflammatory diseases, such as sepsis, in children.

Methods

We genotyped the rs6983267 CCAT2 polymorphism in 474 cases (pediatric sepsis) and 678 controls using TaqMan methods, and odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the strength of associations.

Results

Our results indicate that the rs6983267 T > G polymorphism is significantly associated with an increased risk of sepsis in children (TG and TT: adjusted OR = 1.311, 95% CI = 1.016–1.743, GG and TT: adjusted OR = 1.444, 95% CI = 1.025–2.034 dominant model: GG/TG vs TT adjusted OR = 1.362, 95% CI = 1.055–1.756). Furthermore, the risk effect was more pronounced in children younger than 60 months who were male and who had sepsis.

Conclusion

We found that the CCAT2 gene polymorphism rs6983267 T > G may be associated with an increased risk of pediatric sepsis in southern China. A larger multicenter study should be performed to confirm these results.

Wolf-Hirschhorn syndrome candidate 1 facilitates alveolar macrophage pyroptosis in sepsis-induced acute lung injury through NEK7-mediated NLRP3 inflammasome activation

Sepsis is a complex clinical syndrome with high incidence and mortality. Acute lung injury (ALI) is a common complication of sepsis. At present, there is no effective therapeutic strategy to treat ALI. The SET domain-containing histone methyltransferase Wolf-Hirschhorn syndrome candidate 1 (WHSC1) regulates cancer progression, while its role in sepsis-induced ALI remains unclear. Thus, this study aimed to study the effect of WHSC1 on sepsis-induced ALI and to explore the potential mechanism of action. In the study, LPS treatment induced lung injury. WHSC1 was highly expressed in LPS-induced ALI. Knockdown of WHSC1 attenuated LPS-induced ALI and pyroptosis in vivo. Besides, knockdown of WHSC1 attenuated LPS-induced alveolar macrophage pyroptosis in vitro. Furthermore, NIMA-related kinase-7 (NEK7) expression could be regulated by WHSC1, and NEK7 bound to NLRP3 in alveolar macrophages. Moreover, WHSC1 regulated alveolar macrophage pyroptosis through modulating NEK7-mediated NLRP3 inflammasome activation. In conclusion, WHSC1 was highly expressed in LPS-induced ALI. WHSC1 facilitated alveolar macrophage pyroptosis in sepsis-induced ALI through NEK7-mediated NLRP3 inflammasome activation. WHSC1 may be a valuable target for the therapy of sepsis-induced ALI.

Multifunctional RNase MCPIP1 and its Role in Cardiovascular Diseases

Monocyte chemoattractant protein-1 induced protein 1 (MCPIP1), one of the MCPIP family members, is characterized by the presence of both C-x8-C-x5-C-x3-H (CCCH)- type zinc finger and PilT-N-terminal domains. As a potent regulator of innate immunity, MCPIP1 exerts anti-inflammatory effects through its ribonuclease (RNase) and deubiquitinating enzyme activities to degrade cytokine mRNAs and inhibit nuclear factor- kappa B (NF-κB), respectively. MCPIP1 is expressed not only in immune cells but also in many other cell types, including cardiomyocytes, vascular endothelial cells (ECs) and smooth muscle cells (SMCs). Increasing evidence indicates that MCPIP1 plays a role in the regulation of cardiac functions and is involved in the processes of vascular diseases, such as ischemia-reperfusion (I/R) and atherosclerosis. To better understand the emerging roles of MCPIP1 in the cardiovascular system, we reviewed the current literature with respect to MCPIP1 functions and discussed its association with the pathogenesis of cardiovascular diseases and the implication as a therapeutic target.

The roles of macrophage polarization in the host immune response to sepsis

Sepsis is a life-threatening clinical syndrome caused by infection. Its pathogenesis is complex and entails coagulation dysfunction, inflammation, and immune disorders. Macrophages are important components of innate and adaptive immunity that are highly heterogeneous and plastic. They can polarize into a multi-dimensional spectrum of phenotypes with different functions relating to immune regulation in response to changes in the microenvironment of specific tissues. We reviewed studies that examined the role of macrophage polarization with a focus on the classical activated (M1-like) and alternative activated (M2-like) macrophages as the two main phenotypes involved in the host immune response to sepsis. A complex regulatory network is involved in the process of macrophage polarization, which is influenced by a variety of signaling molecules, transcription factors, epigenetic modifications, and metabolic reprogramming. M1-like macrophages release large quantities of pro-inflammatory mediators, while M2-like macrophages release large quantities of anti-inflammatory mediators. An imbalance between M1-like and M2-like macrophages induces the occurrence and development of sepsis. Therefore, targeted regulation of the process of macrophage polarization could be a useful approach to normalize the immune balance of the host, offering a new treatment modality for different stages of sepsis.

6-Gingerol attenuates ventilator-induced lung injury via anti-inflammation and antioxidative stress by modulating the PPARγ/NF-κBsignalling pathway in rats

Although mechanical ventilation (MV) is indispensable to life-support therapy in critically ill patients, it may promote or aggravatelunginjury known asventilator-inducedlunginjury(VILI). 6-Gingerol is the principal ingredient of ginger with potential anti-inflammatory and antioxidant properties in various diseases. Nevertheless, the role and mechanism of 6-gingerol in the process of VILI has not been explicitly investigated. In the study, we found that pre-treatment with 6-gingerol significantly improved the histological changes and pulmonary oedema, inhibited neutrophil accumulation and the release of early pro-inflammatory cytokines and MPO, and reduced oxidative stress reactions after high MV. Moreover, 6-gingerol treatment also increased PPARγ expression and decreased NF-κB activation in rats subjected to high MV. Furthermore, GW9662, a specific PPARγ inhibitor, was demonstrated to activatethe NF-κB pathway and cancele the protective role of 6-gingerol in VILI. This indicates that 6-gingerol exerted anti-inflammatory and antioxidative stress effects in VILI by activating PPARγ and inhibiting the NF-κBsignalling pathway.

Macrophages in Lung Injury, Repair, and Fibrosis

Fibrosis progression in the lung commonly results in impaired functional gas exchange, respiratory failure, or even death. In addition to the aberrant activation and differentiation of lung fibroblasts, persistent alveolar injury and incomplete repair are the driving factors of lung fibrotic response. Macrophages are activated and polarized in response to lipopolysaccharide- or bleomycin-induced lung injury. The classically activated macrophage (M1) and alternatively activated macrophage (M2) have been extensively investigated in lung injury, repair, and fibrosis. In the present review, we summarized the current data on monocyte-derived macrophages that are recruited to the lung, as well as alveolar resident macrophages and their polarization, pyroptosis, and phagocytosis in acute lung injury (ALI). Additionally, we described how macrophages interact with lung epithelial cells during lung repair. Finally, we emphasized the role of macrophage polarization in the pulmonary fibrotic response, and elucidated the potential benefits of targeting macrophage in alleviating pulmonary fibrosis.

Celastrol alleviates LPS-induced inflammation in BMDMs and acute lung injury in mice via inhibition of p-38 MAPK/MK2 signaling

Objective:

Celastrol is a compound extracted from a medicinal plant Tripterygium wilfordii which has a broad-spectrum anti-inflammatory effect in traditional medicine. However, the effect of celastrol on acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is still unknown.

Methods:

We reported that celastrol alleviated LPS-induced acute lung injury by H&E staining, MPO activity and the expression of cytokines in broncho-alveolar lavage fluid. The effect of celastrol on bone marrow-derived macrophages (BMDMs) after LPS treatment was measured by ELISA and Western blotting.

Results:

In vivo, celastrol reduced the LPS-induced lung edema and MPO activity of lung tissue. Furthermore, the production of inflammatory cytokines IL-6, TNF-α, and KC in bronchoalveolar lavage was reduced. In vitro, upon treatment of LPS, celastrol dose-dependently inhibited the expression of iNOS in BMDMs. Meanwhile, the expression of IL-6, TNF-α, and KC in BMDMs were also inhibited by celastrol treatment. Furthermore, we found that celastrol attenuated the phosphorylation of p38 MAPK and MK2, and inhibited the interaction between p38 MAPK and MK2.

Conclusion:

Our data indicate that celastrol has an anti-inflammatory effect on LPS-induced inflammatory response in vivo and in vitro, suggesting celastrol is a promising compound for the treatment of ALI and ARDS.

Monocyte Chemotactic Protein 1-Induced Protein 1 Is Highly Expressed in Inflammatory Bowel Disease and Negatively Regulates Neutrophil Activities

Monocyte chemotactic protein 1-induced protein 1 (MCPIP-1) is highly expressed in activated immune cells and plays an important role in negatively regulating immune responses. However, its role in regulating neutrophil functions in the pathogenesis of inflammatory bowel disease (IBD) is still unclear. Here, we found that MCPIP-1 was markedly increased at both the transcriptional and translational levels in inflamed mucosa of IBD patients compared with healthy controls, which was mainly expressed in neutrophils. Interestingly, MG-132, a proteasome inhibitor reducing the degradation of MCPIP-1, further facilitated neutrophils to express MCPIP-1 in vitro. Importantly, MCPIP-1 markedly downregulated the production of ROS, MPO, and proinflammatory cytokines (e.g., interleukin-1β, interleukin-6, tumor necrosis factor-α, interleukin-8, and interferon-γ) and suppressed the migration of IBD neutrophils. Consistently, the same functional changes were observed in neutrophils from mice with myeloid-targeted overexpression of MCPIP-1 as MG-132 did. Altogether, these findings suggest that MCPIP-1 plays a negative role in regulating neutrophil activities through suppressing the production of ROS, MPO, and proinflammatory cytokines and inhibiting the migration. MG-132 may partially modulate the function of neutrophils via the induction of MCPIP-1. Therefore, targeting MCPIP-1 or exogenous supplementation of MG-132 may provide a therapeutic approach in the treatment of IBD.

The Anti-Inflammatory Effect of Trichilia martiana C. DC. in the Lipopolysaccharide-Stimulated Inflammatory Response in Macrophages and Airway Epithelial Cells and in LPS-Challenged Mice

A number of species of the genus Trichilia (Meliaceae) exhibit anti-inflammatory effects. However, the effect of Trichilia martiana C. DC. (TM) on lipopolysaccharide (LPS)-induced inflammation has not, to the best of our knowledge, yet been determined. Therefore, in the present study, the antiinflammatory effect of TM on LPS-stimulated RAW264.7 macrophages was evaluated. The ethanol extract of TM (TMEE) significantly inhibited LPS-induced nitric oxide (NO), prostaglandin 2 (PGE₂), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). TMEE also reduced the levels of inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β and IL-6. The upregulation of mitogen-activated protein kinases (MAPKs) and NF-κB activation was revealed to be downregulated following TMEE pretreatment. Furthermore, TMEE was indicated to lead to the nucleus translocation of nuclear factor erythroid-derived 2-related factor 2 (Nrf2) and the expression of heme oxygenase-1 (HO-1). In H292 airway epithelial cells, the pretreatment of TMEE significantly downregulated the production of LPS-stimulated IL-1β, and TMEE was indicated to increase the expression of HO-1. In animal models exhibiting LPS-induced acute lung injury (ALI), treatment with TMEE reduced the levels of macrophages influx and TNF-α production in the bronchoalveolar lavage fluid (BALF) of ALI mice. Additionally, TMEE significantly downregulated the activation of ERK, JNK and IκB, and upregulated the expression of HO-1 in the lungs of ALI mice. In conclusion, the results of the current study demonstrated that TMEE could exert a regulatory role in the prevention or treatment of the endotoxin-mediated inflammatory response.

Cytosolic DNA-STING-NLRP3 axis is involved in murine acute lung injury induced by lipopolysaccharide

The role of NOD-like receptor protein 3 (NLRP3)-mediated pyroptosis in acute lung injury (ALI) has been well identified previously. Stimulator of interferon genes (STING) is an indispensable adaptor protein, which could regulate inflammation and pyroptosis during infection; however, its role in lipopolysaccharide (LPS)-induced ALI remains obscure. This study aimed to explore whether STING participated in the development of LPS-induced ALI as well as the underlying mechanism. We confirmed that LPS significantly enhanced the expression and phosphorylation of STING in lung tissue and primary macrophages from mice. STING deficiency relieved inflammation and oxidative stress in LPS-treated murine lungs and macrophages. Meanwhile, STING deficiency also abolished the activation of NLRP3 inflammasome and pyroptosis; however, NLRP3 overexpression by adenovirus offset the beneficial effects of STING deficiency in macrophages treated with LPS. Additionally, the level of mitochondrial DNA (mt-DNA) significantly increased in macrophages after LPS treatment. Intriguingly, although exogenous mt-DNA stimulation did not influence the level of STING, it could still trigger the phosphorylation of STING as well as pyroptosis, inflammation, and oxidative stress of macrophages. And the adverse effects induced by mt-DNA could be offset after STING was knocked out. Furthermore, the inhibition of the sensory receptor of cytosolic DNA (cyclic GMP-AMP synthase, cGAS) also blocked the activation of STING and NLRP3 inflammasome, meanwhile, it alleviated ALI without affecting the expression of STING after LPS challenge. Furthermore, cGAS inhibition also blocked the production of cGAMP induced by LPS, indicating that mt-DNA and cGAS could activate STING-NLRP3-mediated pyroptosis independent of the expression of STING. Finally, we found that LPS upregulated the expression of transcription factor c-Myc, which subsequently enhanced the activity of STING promoter and promoted its expression without affecting its phosphorylation. Collectively, our study disclosed that LPS could activate STING in a cytosolic DNA-dependent manner and upregulate the expression of STING in a c-Myc-dependent manner, which cooperatively contribute to ALI.

The immunomodulatory role of Regnase family RNA-binding proteins

RNA-binding proteins regulate RNA fate and govern post-transcriptional gene regulation. A new family of RNA-binding proteins is represented by regulatory RNases (Regnase, also known as Zc3h12 or MCPIP), which have emerged as important players in immune homoeostasis. Four members, Regnase1-4, have been identified to date. Here we summarize recent findings on the role of Regnase in the regulation of RNA biology and its consequences for cell functions and inflammatory processes.

Inhibition of the endoplasmic reticulum (ER) stress-associated IRE-1/XBP-1 pathway alleviates acute lung injury via modulation of macrophage activation

Background

Both endoplasmic reticulum (ER) stress and macrophage diversity contribute to inflammatory processes in lung injury. However, the interaction between ER stress and macrophage M1/M2 imbalance in lung inflammation remains unclear. The present study, thus, aimed to evaluate the role of ER stress-mediated macrophage phenotype changes in lipopolysaccharide (LPS)-induced acute lung injury (ALI).

Methods

Lung inflammation and injury were examined in a murine model of LPS-induced ALI with or without ER stress inhibitors. Alveolar macrophage (AM) polarization was determined by flow cytometry. Bone marrow-derived macrophages (BMDMs) were treated with either an ER stress inducer, inhibitor, or an IRE-1 endonuclease inhibitor before being polarized to an M1 and M2 phenotype. The macrophage polarization status was examined via RT-PCR and flow cytometry.

Results

Our results indicated that ER stress and IRE-1/XBP-1 signaling are activated in LPS-induced ALI. Furthermore, we observed that AM polarizes to an inflammatory phenotype upon exposure to LPS in the induction phase and an anti-inflammatory phenotype in the resolution phase of lung inflammation. Inhibition of ER stress attenuated the pathophysiological features of LPS-induced lung inflammation/injury, as evidenced by a decrease in bronchoalveolar lavage (BAL) protein levels, the number of inflammatory cells, and the expression level of inflammatory mediators. In addition, the ER stress inducer promoted M1 polarization and the switch from M2 to M1 in BMDMs, whereas inhibition of ER stress and XBP-1 splicing suppressed M1 but did not promote M2, both in vivo and in vitro.

Conclusions

Our results demonstrated that inhibition of the ER stress-associated IRE-1/XBP-1 signaling pathway suppresses M1 polarization and ameliorates LPS-induced lung injury. This indicates that the interaction between ER stress and macrophage polarization might be a novel therapeutic target for endotoxin-induced lung inflammatory disorders.