Gut-Lung Crosstalk in Sepsis-Induced Acute Lung Injury

Multi-metabolomics and intestine microbiome analysis: YZC extract ameliorates septic-ALI by modulating intestine microbiota to reduce TMAO/NLRP3 signaling

BACKGROUND

Sepsis causes inflammation in response to infection, often leading to acute lung injury (ALI). Yazhicao (Commelina communis L., YZC) is widely distributed in the global tropics and has good anti-respiratory inflammatory activity; however, the protection of YZC against septic-ALI has not been established.

PURPOSE

The role of YZC in septic-ALI will be investigated in this study.

METHODS AND RESULTS

In this study, YZC was shown to inhibit excessive inflammation and alleviate septic-ALI. Network pharmacology predicts that Quercetin, Acacetin and Diosmetin have the potential to serve as the pharmacological substance basis of YZC in alleviating septic-ALI. The metabolomics results indicated that YZC could improve the metabolic disorders caused by septic-ALI, which were mostly concerned with energy metabolism and amino acid metabolism, with Trimethylamine (TMA)/Trimethylamine N-oxide (TMAO) being potential small molecule metabolic markers for the clinical diagnosis and treatment of septic-ALI. YZC inhibits the initiation and progression of septic-ALI by controlling the TMA/TMAO metabolites. Our results also suggest that YZC protects the intestinal barrier from damage. Furthermore, our research indicated that YZC reduces TMAO synthesis by inhibiting TMA production through remodeling the intestine microbiota. We investigated the mechanism of YZC-mediated protection against septic-ALI and showed that YZC reduced the expression of proteins associated with NLRP3 inflammatory vesicles in the lung by inhibiting the expression of NF-κB.

CONCLUSION

These results show that YZC inhibits the NF-κB/NLRP3 signaling pathway by regulating metabolic and intestinal flora disorders in septic-ALI mice to reduce TMAO synthesis. This study presents a theoretical groundwork for the advancement of novel medications and clinical use of YZC to enhance septic-ALI and furnishes a theoretical rationale for regulating intestinal microbiota as a therapeutic instrument to treat sepsis and septic-ALI.

Exploring immune-related pathogenesis in lung injury: Providing new insights Into ALI/ARDS

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) represent a significant global burden of morbidity and mortality, with lung injury being the primary cause of death in affected patients. The pathogenesis of lung injury, however, remains a complex issue. In recent years, the role of the immune system in lung injury has attracted extensive attention worldwide. Despite advancements in our understanding of various lung injury subtypes, significant limitations persist in both prevention and treatment. This review investigates the immunopathogenesis of ALI/ARDS, aiming to elucidate the pathological processes of lung injury mediated by dendritic cells (DCs), natural killer (NK) cells, phagocytes, and neutrophils. Furthermore, the article expounds on the critical contributions of gut microbiota, inflammatory pathways, and cytokine storms in the development of ALI/ARDS.

Exploring the lung-gut direction of the gut-lung axis in patients with ARDS

Acute respiratory distress syndrome (ARDS) represents a life-threatening inflammatory reaction marked by refractory hypoxaemia and pulmonary oedema. Despite advancements in treatment perspectives, ARDS still carries a high mortality rate, often due to systemic inflammatory responses leading to multiple organ dysfunction syndrome (MODS). Indeed, the deterioration and associated mortality in patients with acute lung injury (LI)/ARDS is believed to originate alongside respiratory failure mainly from the involvement of extrapulmonary organs, a consequence of the complex interaction between initial inflammatory cascades related to the primary event and ongoing mechanical ventilation-induced injury resulting in multiple organ failure (MOF) and potentially death. Even though recent research has increasingly highlighted the role of the gastrointestinal tract in this process, the pathophysiology of gut dysfunction in patients with ARDS remains mainly underexplored. This review aims to elucidate the complex interplay between lung and gut in patients with LI/ARDS. We will examine various factors, including systemic inflammation, epithelial barrier dysfunction, the effects of mechanical ventilation (MV), hypercapnia, and gut dysbiosis. Understanding these factors and their interaction may provide valuable insights into the pathophysiology of ARDS and potential therapeutic strategies to improve patient outcomes.

Mechanisms underlying the synergistic effects of chuanxiong combined with Chishao on treating acute lung injury based on network pharmacology and molecular docking combined with preclinical evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

The herb pair of Chuanxiong Rhizome (Ligusticum chuanxiong Hort., Chuanxiong in Chinese, CX) and Paeoniae Radix Rubra (Paeonia lactiflora Pall. Or Paeonia veitchii Lynch, Chishao in Chinese, CS) is a famous blood activating and stasis resolving pair that is often found in traditional Chinese medicine (TCM) formulas for the treatment of acute lung injury (ALI). However, the relationship of CX-CS herb pair to ALI and its underlying mechanisms are unclear.

AIM OF THE STUDY

The study explored the effect and mechanisms of CX-CS herb pair in LPS induced ALI by network pharmacology and molecular docking combined with preclinical evaluation.

MATERIALS AND METHODS

The related targets of the active compounds of CX-CS herb pair in regulating ALI were screened by network pharmacology. PPI was constructed and the potential pathways were investigated by GO and KEGG. The contribution of each active ingredient of CX-CS herb pair to ALI were calculated by network-based efficacy. The interactions between potential targets and active ingredients were evaluated by molecular docking. LPS stimulated RAW264.7 cells and mice model experiments were adopted to verify the effect of CX-CS herb pair on ALI.

RESULTS

A total of 25 compounds and 193 targets were identified in the CX-CS herb pair, of which 19 compounds and 64 targets were associated with ALI, and six compounds including baicalin, ellagic acid, baicalein, beta-sitosterol, paeoniflorin and ferulic acid accounted for 93.12% of the total combination index for ALI prevention. The CX-CS herbal pair against ALI was associated with PI3K/AKT and MAPK signaling pathways by GO and KEGG analysis. The screened active compounds showed good affinity for TNF, MAPK, and AKT by molecular docking. In vitro and in vivo tests showed that CX combined with CS synergistically inhibited LPS-induced ALI at 1:3, suppressed the release of TNF-α, IL-1β and IL-6, inhibited the accumulation of ROS, as well as regulated the content of SOD, MDA and GSH. Meanwhile, the herb pair was effective in inhibiting the expression of p38, ERK, IκBα, p65, caspase 3, PARP, and up-regulating the levels of AKT and Bcl-2/Bax.

CONCLUSIONS

Our study confirmed the synergistic effect of CX-CS herb pair on the prevention of ALI by inhibiting inflammation, oxidative stress, and apoptosis through MAPK/NF-κB and PI3K/AKT signaling pathways.

Preventive Effect of the Total Polyphenols from Nymphaea candida on Sepsis-Induced Acute Lung Injury in Mice via Gut Microbiota and NLRP3, TLR-4/NF-κB Pathway

This study aimed to investigate the preventive effects of the total polyphenols from Nymphaea candida (NCTP) on LPS-induced septic acute lung injury (ALI) in mice and its mechanisms. NCTP could significantly ameliorate LPS-induced lung tissue pathological injury in mice as well as lung wet/dry ratio and MPO activities (p < 0.05). NCTP could significantly decrease the blood leukocyte, neutrophil, monocyte, basophil, and eosinophil amounts and LPS contents in ALI mice compared with the model group (p < 0.05), improving lymphocyte amounts (p < 0.05). Moreover, compared with the model group, NCTP could decrease lung tissue TNF-α, IL-6, and IL-1β levels (p < 0.05) and downregulate the protein expression of TLR4, MyD88, TRAF6, IKKβ, IκB-α, p-IκB-α, NF-κB p65, p-NF-κB p65, NLRP3, ASC, and Caspase1 in lung tissues (p < 0.05). Furthermore, NCTP could inhibit ileum histopathological injuries, restoring the ileum tight junctions by increasing the expression of ZO-1 and occludin. Simultaneously, NCTP could reverse the gut microbiota disorder, restore the diversity of gut microbiota, increase the relative abundance of Clostridiales and Lachnospiraceae, and enhance the content of SCFAs (acetic acid, propionic acid, and butyric acid) in feces. These results suggested that NCTP has preventive effects on septic ALI, and its mechanism is related to the regulation of gut microbiota, SCFA metabolism, and the TLR-4/NF-κB and NLRP3 pathways.

Mechanisms of Sepsis-Induced Acute Lung Injury and Advancements of Natural Small Molecules in Its Treatment

Sepsis-induced acute lung injury (ALI), characterized by widespread lung dysfunction, is associated with significant morbidity and mortality due to the lack of effective pharmacological treatments available clinically. Small-molecule compounds derived from natural products represent an innovative source and have demonstrated therapeutic potential against sepsis-induced ALI. These natural small molecules may provide a promising alternative treatment option for sepsis-induced ALI. This review aims to summarize the pathogenesis of sepsis and potential therapeutic targets. It assembles critical updates (from 2014 to 2024) on natural small molecules with therapeutic potential against sepsis-induced ALI, detailing their sources, structures, effects, and mechanisms of action.

Therapeutic potential of ADSC-EV-derived lncRNA DLEU2: A novel molecular pathway in alleviating sepsis-induced lung injury via the miR-106a-5p/LXN axis

This study investigates the molecular mechanisms by which extracellular vesicles (EVs) derived from adipose-derived mesenchymal stem cells (ADSCs) promote M2 polarization of macrophages and thus reduce lung injury caused by sepsis. High-throughput sequencing was used to identify differentially expressed genes related to long non-coding RNA (lncRNA) in ADSC-derived EVs (ADSC-EVs) in sepsis lung tissue. Weighted gene co-expression network analysis (WGCNA) was employed to predict the downstream target genes of the lncRNA DLEU2. The RNAInter database predicted miRNAs that interact with DLEU2 and LXN. Functional and pathway enrichment analyses were performed using GO and KEGG analysis. A mouse model of sepsis was established, and treatment with a placebo or ADSC-EVs was administered, followed by RT-qPCR analysis. ADSC-EVs were isolated and identified. In vitro cell experiments were conducted using the mouse lung epithelial cell line MLE-12, mouse macrophage cell line RAW264.7, and mouse lung epithelial cell line (LEPC). ADSC-EVs were co-cultured with RAW264.7 and MLE-12/LEPC cells to study the regulatory mechanism of the lncRNA DLEU2. Cell viability, proliferation, and apoptosis of lung injury cells were assessed using CCK-8, EdU, and flow cytometry. ELISA was used to measure the levels of inflammatory cytokines in the sepsis mouse model, flow cytometry was performed to determine the number of M1 and M2 macrophages, lung tissue pathology was evaluated by H&E staining, and immunohistochemistry was conducted to examine the expression of proliferation- and apoptosis-related proteins. High-throughput sequencing and bioinformatics analysis revealed enrichment of the lncRNA DLEU2 in ADSC-EVs in sepsis lung tissue. Animal and in vitro cell experiments showed increased expression of the lncRNA DLEU2 in sepsis lung tissue after treatment with ADSC-EVs. Furthermore, ADSC-EVs were found to transfer the lncRNA DLEU2 to macrophages, promoting M2 polarization, reducing inflammation response in lung injury cells, and enhancing their viability, proliferation, and apoptosis inhibition. Further functional experiments indicated that lncRNA DLEU2 promotes M2 polarization of macrophages by regulating miR-106a-5p/LXN, thereby enhancing the viability and proliferation of lung injury cells and inhibiting apoptosis. Overexpression of miR-106a-5p could reverse the biological effects of ADSC-EVs-DLEU2 on MLE-12 and LEPC in vitro cell models. Lastly, in vivo animal experiments confirmed that ADSC-EVs-DLEU2 promotes high expression of LXN by inhibiting the expression of miR-106a-5p, further facilitating M2 macrophage polarization and reducing lung edema, thus alleviating sepsis-induced lung injury. lncRNA DLEU2 in ADSC-EVs may promote M2 polarization of macrophages and enhance the viability and proliferation of lung injury cells while inhibiting inflammation and apoptosis reactions, thus ameliorating sepsis-induced lung injury in a mechanism involving the regulation of the miR-106a-5p/LXN axis.

LL-37 improves sepsis-induced acute lung injury by suppressing pyroptosis in alveolar epithelial cells

BACKGROUND

LL-37 (also known as murine CRAMP) is a human antimicrobial peptide that plays a crucial role in innate immune defence against sepsis through various mechanisms. However, its involvement in sepsis-induced lung injury remains unclear.

OBJECTIVES

This work investigates the impact of LL-37 on pyroptosis generated by LPS in alveolar epithelial cells. The research utilizes both in vivo and in vitro sepsis-associated acute lung injury (ALI) models to understand the underlying molecular pathways.

METHODS

In vivo, an acute lung injury model induced by sepsis was established by intratracheal administration of LPS in C57BL/6J mice, which were subsequently treated with low-dose CRAMP (recombinant murine cathelicidin, 2.5 mg.kg-1) and high-dose CRAMP (5.0 mg.kg-1). In vitro, pyroptosis was induced in a human alveolar epithelial cell line (A549) by stimulation with LPS and ATP. Treatment was carried out with recombinant human LL-37, or LL-37 was knocked out in A549 cells using small interfering RNA (siRNA). Subsequently, haematoxylin and eosin staining was performed to observe the histopathological changes in lung tissues in the control group and sepsis-induced lung injury group. TUNEL and PI staining were used to observe DNA fragmentation and pyroptosis in mouse lung tissues and cells in the different groups. An lactate dehydrogenase (LDH) assay was performed to measure the cell death rate. The expression levels of NLRP3, caspase1, caspase 1 p20, GSDMD, NT-GSDMD, and CRAMP were detected in mice and cells using Western blotting, qPCR, and immunohistochemistry. ELISA was used to assess the levels of interleukin (IL)-1β and IL-18 in mouse serum, bronchoalveolar lavage fluid (BALF) and lung tissue and cell culture supernatants.

RESULTS

The expression of NLRP3, caspase1 p20, NT-GSDMD, IL 18 and IL1β in the lung tissue of mice with septic lung injury was increased, which indicated activation of the canonical pyroptosis pathway and coincided with an increase in CRAMP expression. Treatment with recombinant CRAMP improved pyroptosis in mice with lung injury. In vitro, treatment with LPS and ATP upregulated these classic pyroptosis molecules, LL-37 knockdown exacerbated pyroptosis, and recombinant human LL-37 treatment alleviated pyroptosis in alveolar epithelial cells.

CONCLUSION

These findings indicate that LL-37 protects against septic lung injury by modulating the expression of classic pyroptotic pathway components, including NLRP3, caspase1, and GSDMD and downstream inflammatory factors in alveolar epithelial cells.

Pathophysiology of acute lung injury in patients with acute brain injury: the triple-hit hypothesis

It has been convincingly demonstrated in recent years that isolated acute brain injury (ABI) may cause severe dysfunction of peripheral extracranial organs and systems. Of all potential target organs and systems, the lung appears to be the most vulnerable to damage after ABI. The pathophysiology of the bidirectional brain-lung interactions is multifactorial and involves inflammatory cascades, immune suppression, and dysfunction of the autonomic system. Indeed, the systemic effects of inflammatory mediators in patients with ABI create a systemic inflammatory environment ("first hit") that makes extracranial organs vulnerable to secondary procedures that enhance inflammation, such as mechanical ventilation (MV), surgery, and infections ("second hit"). Moreover, accumulating evidence supports the knowledge that gut microbiota constitutes a critical superorganism and an organ on its own, potentially modifying various physiological functions of the host. Furthermore, experimental and clinical data suggest the existence of a communication network among the brain, gastrointestinal tract, and its microbiome, which appears to regulate immune responses, gastrointestinal function, brain function, behavior, and stress responses, also named the "gut-microbiome-brain axis." Additionally, recent research evidence has highlighted a crucial interplay between the intestinal microbiota and the lungs, referred to as the "gut-lung axis," in which alterations during critical illness could result in bacterial translocation, sustained inflammation, lung injury, and pulmonary fibrosis. In the present work, we aimed to further elucidate the pathophysiology of acute lung injury (ALI) in patients with ABI by attempting to develop the "double-hit" theory, proposing the "triple-hit" hypothesis, focused on the influence of the gut-lung axis on the lung. Particularly, we propose, in addition to sympathetic hyperactivity, blast theory, and double-hit theory, that dysbiosis and intestinal dysfunction in the context of ABI alter the gut-lung axis, resulting in the development or further aggravation of existing ALI, which constitutes the "third hit."

The value of five scoring systems in predicting the prognosis of patients with sepsis-associated acute respiratory failure

Our study aimed to identify the optimal scoring system for predicting the prognosis of patients with sepsis-associated acute respiratory failure (SA-ARF). All data were taken from the fourth version of the Markets in Intensive Care Medicine (MIMIC-IV) database. Independent risk factors for death in hospitals were confirmed by regression analysis. The predictive value of the five scoring systems was evaluated by receiving operating characteristic (ROC) curves. Kaplan‒Meier curves showed the impact of acute physiology score III (APSIII) on survival and prognosis in patients with SA-ARF. Decision curve analysis (DCA) identified a scoring system with the highest net clinical benefit. ROC curve analysis showed that APS III (AUC: 0.755, 95% Cl 0.714-0.768) and Logical Organ Dysfunction System (LODS) (AUC: 0.731, 95% Cl 0.717-0.7745) were better than Simplified Acute Physiology Score II (SAPS II) (AUC: 0.727, 95% CI 0.713-0.741), Oxford Acute Severity of Illness Score (OASIS) (AUC: 0.706, 95% CI 0.691-0.720) and Sequential Organ Failure Assessment (SOFA) (AUC: 0.606, 95% CI 0.590-0.621) in assessing in-hospital mortality. Kaplan‒Meier survival analysis patients in the high-APS III score group had a considerably poorer median survival time. The DCA curve showed that APS III may provide better clinical benefits for patients. We demonstrated that the APS III score is an excellent predictor of in-hospital mortality.

Gut microbiota and its metabolic products in acute respiratory distress syndrome

The prevalence rate of acute respiratory distress syndrome (ARDS) is estimated at approximately 10% in critically ill patients worldwide, with the mortality rate ranging from 17% to 39%. Currently, ARDS mortality is usually higher in patients with COVID-19, giving another challenge for ARDS treatment. However, the treatment efficacy for ARDS is far from satisfactory. The relationship between the gut microbiota and ARDS has been substantiated by relevant scientific studies. ARDS not only changes the distribution of gut microbiota, but also influences intestinal mucosal barrier through the alteration of gut microbiota. The modulation of gut microbiota can impact the onset and progression of ARDS by triggering dysfunctions in inflammatory response and immune cells, oxidative stress, cell apoptosis, autophagy, pyroptosis, and ferroptosis mechanisms. Meanwhile, ARDS may also influence the distribution of metabolic products of gut microbiota. In this review, we focus on the impact of ARDS on gut microbiota and how the alteration of gut microbiota further influences the immune function, cellular functions and related signaling pathways during ARDS. The roles of gut microbiota-derived metabolites in the development and occurrence of ARDS are also discussed.

Knockdown of angiopoietin-like 4 suppresses sepsis-induced acute lung injury by blocking the NF-κB pathway activation and hindering macrophage M1 polarization and pyroptosis

OBJECTIVE

Sepsis-induced acute lung injury (ALI) is a life-threatening disease. Macrophage pyroptosis has been reported to exert function in ALI. We aimed to investigate the mechanisms of ANGPTL4-mediated cell pyroptosis in sepsis-induced ALI, thus providing new insights into the pathogenesis and prevention and treatment measures of sepsis-induced ALI.

METHODS

In vivo animal models and in vitro cell models were established by cecal ligation and puncture (CLP) method and lipopolysaccharide-induced macrophages RAW264.7. ANGPTL4 was silenced in CLP mice or macrophages, followed by the determination of ANGPTL4 expression in bronchoalveolar lavage fluid (BALF) or macrophages. Lung histopathology was observed by H&E staining, with pathological injury scores evaluated and lung wet and dry weight ratio recorded. M1/M2 macrophage marker levels (iNOS/CD86/Arg1), inflammatory factor (TNF-α/IL-6/IL-1β/iNOS) expression in BALF, cell death and pyroptosis, NLRP3 inflammasome, cell pyroptosis-related protein (NLRP3/Cleaved-caspase-1/caspase-1/GSDMD-N) levels, NF-κB pathway activation were assessed by RT-qPCR/ELISA/flow cytometry/Western blot, respectively.

RESULTS

ANGPTL4 was highly expressed in mice with sepsis-induced ALI, and ANGPTL4 silencing ameliorated sepsis-induced ALI in mice. In vivo, ANGPTL4 silencing repressed M1 macrophage polarization and macrophage pyroptosis in mice with sepsis-induced ALI. In vitro, ANGPTL4 knockout impeded LPS-induced activation and pyroptosis of M1 macrophages and hindered LPS-induced activation of the NF-κB pathway in macrophages.

CONCLUSION

Knockdown of ANGPTL4 blocks the NF-κB pathway activation, hinders macrophage M1 polarization and pyroptosis, thereby suppressing sepsis-induced ALI.

Rhei Radix et Rhizoma in Xuanbai-Chengqi decoction strengthens the intestinal barrier function and promotes lung barrier repair in preventing severe viral pneumonia induced by influenza A virus

ETHNOPHARMACOLOGICAL RELEVANCE

Xuanbai-Chengqi decoction (XCD) is a traditional prescription for treating multiple organ injuries, which has been used to manage pneumonia caused by various pathogens. However, the effects of XCD on repairing pulmonary/intestinal barrier damage remain unclear, and there is a need to understand the compatibility mechanism of rhubarb.

AIM OF THE STUDY

This work aims to investigate the protective effect and mechanism of XCD on the pulmonary/intestinal barrier guided by the theory of "gut-lung concurrent treatment". Moreover, we elucidate the compatibility mechanism of rhubarb in XCD.

MATERIALS AND METHODS

An H1N1 virus-infected mouse model was adopted to investigate the reparative effects of XCD on the lung-intestinal barrier by assessing lung-intestinal permeability. Additionally, the characterization of type I alveolar epithelial cells (AT1) and type II alveolar epithelial cells (AT2) was performed to evaluate the damage to the alveolar epithelial barrier. The specific barrier-protective mechanisms of XCD were elucidated by detecting tight junction proteins and the epithelial cell repair factor IL-22. The role of rhubarb in XCD to pneumonia treatment was investigated through lung tissue transcriptome sequencing and flow cytometry.

RESULTS

XCD significantly improved lung tissue edema, inflammation, and alveolar epithelial barrier damage by regulating IL-6, IL-10, and IL-22, which, could further improve pulmonary barrier permeability when combined with the protection of alveolar epithelial cells (AT1 and AT2) as well as inhibition of H1N1 virus replication. Simultaneously, XCD significantly reduced intestinal inflammation and barrier damage by regulating IL-6, IL-1β, and tight junction protein levels (Claudin-1 and ZO-1), improving intestinal barrier permeability. The role of rhubarb in the treatment of pneumonia is clarified for the first time. In the progression of severe pneumonia, rhubarb can significantly protect the intestinal barrier, promote the repair of AT2 cells, and inhibit the accumulation of CD11b+Ly6Gvariable aberrant neutrophils by regulating the S100A8 protein.

CONCLUSION

In summary, our findings suggest that rhubarb in XCD plays a critical role in protecting intestinal barrier function and promoting lung barrier repair in preventing severe viral pneumonia caused by influenza A virus.

Lung microbiome: new insights into the pathogenesis of respiratory diseases

The lungs were long thought to be sterile until technical advances uncovered the presence of the lung microbial community. The microbiome of healthy lungs is mainly derived from the upper respiratory tract (URT) microbiome but also has its own characteristic flora. The selection mechanisms in the lung, including clearance by coughing, pulmonary macrophages, the oscillation of respiratory cilia, and bacterial inhibition by alveolar surfactant, keep the microbiome transient and mobile, which is different from the microbiome in other organs. The pulmonary bacteriome has been intensively studied recently, but relatively little research has focused on the mycobiome and virome. This up-to-date review retrospectively summarizes the lung microbiome's history, composition, and function. We focus on the interaction of the lung microbiome with the oropharynx and gut microbiome and emphasize the role it plays in the innate and adaptive immune responses. More importantly, we focus on multiple respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), fibrosis, bronchiectasis, and pneumonia. The impact of the lung microbiome on coronavirus disease 2019 (COVID-19) and lung cancer has also been comprehensively studied. Furthermore, by summarizing the therapeutic potential of the lung microbiome in lung diseases and examining the shortcomings of the field, we propose an outlook of the direction of lung microbiome research.

Radix Sanguisorbae Improves Intestinal Barrier in Septic Rats via HIF-1 α/HO-1/Fe2+ Axis

OBJECTIVE

To investigate whether Radix Sanguisorbae (RS, Diyu) could restore intestinal barrier function following sepsis using a cecal ligation and puncture (CLP)-induced septic rat model and lipopolysaccharide (LPS)-challenged IEC-6 cell model, respectively.

METHODS

Totally 224 rats were divided into 4 groups including a control, sham, CLP and RS group according to a random number table. The rats in the control group were administrated with Ringer's lactate solution (30 mL/kg) with additional dopamine [10 µ g/(kg·min)] and given intramuscular injections of cefuroxime sodium (10 mg/kg) 12 h following CLP. The rats in the RS group were administrated with RS (10 mg/kg) through tail vein 1 h before CLP and treated with RS (10 mg/kg) 12 h following CLP. The rats in the sham group were only performed abdominal surgery without CLP. The rats in the CLP group were performed with CLP without any treatment. The other steps were same as control group. The effects of RS on intestinal barrier function, mesenteric microvessels barrier function, multi-organ function indicators, inflammatory response and 72 h survival window following sepsis were observed. In vitro, the effects of RS on LPS-challenged IEC-6 cell viability, the expressions of zona occludens-1 (ZO-1) and ferroptosis index were evaluated by cell counting kit-8, immunofluorescence and Western blot analysis. Bioinformatic tools were applied to investigate the pharmacological network of RS in sepsis to predict the active compounds and potential protein targets and pathways.

RESULTS

The sepsis caused severe intestinal barrier dysfunction, multi-organ injury, lipid peroxidation accumulation, and ferroptosis in vivo. RS treatment significantly prolonged the survival time to 56 h and increased 72-h survival rate to 7/16 (43.75%). RS also improved intestinal barrier function and relieved intestinal inflammation. Moreover, RS significantly decreased lipid peroxidation and inhibited ferroptosis (P<0.05 or P<0.01). Administration of RS significantly worked better than Ringer's solution used alone. Using network pharmacology prediction, we found that ferroptosis and hypoxia inducible factor-1 (HIF-1 α) signaling pathways might be involved in RS effects on sepsis. Subsequent Western blot, ferrous iron measurements, and FerroOrange fluorescence of ferrous iron verified the network pharmacology predictions.

CONCLUSION

RS improved the intestinal barrier function and alleviated intestinal injury by inhibiting ferroptosis, which was related in part to HIF-1 α/heme oxygenase-1/Fe2+ axis.

Design and synthesis of novel hederagonic acid analogs as potent anti-inflammatory compounds capable of protecting against LPS-induced acute lung injury

Acute lung injury (ALI) presents a significant clinical challenge due to its high mortality rates and the lack of effective treatment strategies. The most effective approaches to treating ALI include disrupting inflammatory cascades and associated inflammatory damage within the lung. Hederagenin was utilized as a core skeleton to design and synthesize 33 hederagonic acid derivatives. Among these derivatives, compound 29 demonstrated potent anti-inflammatory activity without inducing cytotoxicity, inhibiting nitric oxide (NO) release by 78-86 %. Detailed structure-activity relationship studies and the reverse virtual screening of ALI-related targets revealed that compound 29 exhibits a high affinity for the STING protein. Mechanistic studies revealed that compound 29 suppresses macrophage activation, inhibits the nuclear translocation of IRF3 and p65, and disrupts the STING/IRF3/NF-κB signaling pathway, thereby attenuating the inflammatory response. The in vivo administration of compound 29 was sufficient to protect against lipopolysaccharide (LPS)-induced ALI by suppressing the production of inflammatory mediators, including IL-6, TNF-α, and IFN-β, thereby preserving lung tissue integrity. These results substantiate the anti-inflammatory efficacy of compound 29, both in vitro and in vivo, indicating its potential as a promising lead compound in ALI treatment strategies.

Lactobacillus rhamnosus (LR) ameliorates pulmonary and extrapulmonary acute respiratory distress syndrome (ARDS) via targeting neutrophils

Pulmonary and extrapulmonary acute respiratory distress syndrome (ARDS) is a life-threatening respiratory failure associated with high mortality. Despite progress in our understanding of the pathological mechanism causing the crippling illness, there are currently no targeted pharmaceutical treatments available for it. Recent discoveries have emphasized the existence of a potential nexus between gut and lung health fueling novel approaches including probiotics for the treatment of ARDS. We thus investigated the prophylactic-potential of Lactobacillus rhamnosus-(LR) in lipopolysaccharide (LPS)-induced pulmonary and cecal ligation puncture (CLP) induced extrapulmonary ARDS mice. Our in-vivo findings revealed that pretreatment with LR significantly ameliorated vascular-permeability (edema) of the lungs via modulating the neutrophils along with significantly reducing the expression of inflammatory-cytokines in the BALF, lungs and serum in both pulmonary and extrapulmonary mice-models. Interestingly, our ex-vivo immunofluorescence and flow cytometric data suggested that mechanistically LR via short chain fatty acids (butyrate being the most potent and efficient in ameliorating the pathophysiology of both pulmonary and extra-pulmonary ARDS) targets the phagocytic and neutrophils extracellular traps (NETs) releasing potential of neutrophils. Moreover, our in-vivo data further corroborated our ex-vivo findings and suggested that butyrate exhibits enhanced potential in ameliorating the pathophysiology of ARDS via reducing the infiltration of neutrophils into the lungs. Altogether, our study establishes the prophylactic role of LR and its associated metabolites in the prevention and management of both pulmonary and extrapulmonary ARDS via targeting neutrophils.

ASTRAGALOSIDE Ⅳ MODULATES GUT MACROPHAGES M1/M2 POLARIZATION BY RESHAPING GUT MICROBIOTA AND SHORT CHAIN FATTY ACIDS IN SEPSIS

ABSTRACT

M1 macrophage-mediated inflammation is critical in sepsis. We previously found the protective role of astragaloside intravenous (AS-IV) in sepsis-associated gut impairment, whose specific mechanism remains unknown. Gut microbiota modulates gut homeostatic balance to avoid excessive inflammation. Here, we aimed to investigate effects of AS-IV on gut macrophages polarization and potential roles of gut microbiota and short chain fatty acids (SCFAs) in septic gut damage. Mice were pretreated by AS-IV gavage for 7 days before cecal ligation and puncture. M1 polarization of gut lamina propria macrophages (LpMs) was promoted by cecal ligation and puncture, accompanied by abnormal cytokines release and intestinal barrier dysfunction. NLRP3 inflammasome was activated in M1 LpMs. 16S rRNA sequencing demonstrated gut microbiota imbalance. The levels of acetate, propionate, and butyrate in fecal samples decreased. Notably, AS-IV reversed LpMs M1/M2 polarization, lightened gut inflammation and barrier injury, reduced NLRP3 inflammasome expression in LpMs, restored the diversity of gut microbiome, and increased butyrate levels. Similarly, these benefits were mimicked by fecal microbiota transplantation or exogenous butyrate supplementation. In Caco-2 and THP-1 cocultured model, LPS and interferon γ caused THP-1 M1 polarization, Caco-2 barrier impairment, abnormal cytokines release, and high NLRP3 inflammasome expression in THP-1 cells, all of which were mitigated by butyrate administration. However, these protective effects of butyrate were abrogated by NLRP3 gene overexpression in THP-1. In conclusion, AS-IV can ameliorate sepsis-induced gut inflammation and barrier dysfunction by modulating M1/M2 polarization of gut macrophages, whose underlying mechanism may be restoring gut microbiome and SCFA to restrain NLRP3 inflammasome activation.

Activation of toll-like receptor 4/nuclear factor-kappa B signaling by triggering a receptor expressed on myeloid cells 1 promotes alveolar macrophage M1 polarization and exacerbates septic acute lung injury

BACKGROUND

Septic acute lung injury (ALI) is a life-threatening condition commonly occurring in the intensive care unit. Inflammation is considered as the basic pathological response of septic ALI. Triggering receptor expressed on myeloid cells 1 (TREM1) is a member of the immunoglobulin superfamily receptors that regulates the inflammatory response. However, the role of TREM1 in septic ALI has not yet been reported.

METHODS

Cell viability was tested using the MTT assay. TdT-mediated dUTP nick end labeling assay and flow cytometry were used for apoptosis. The level of protein was detected using western blot analysis. The levels of tumor necrosis factor-α and interleukin-1β were assessed using enzyme-linked immunosorbent assay. The lactate dehydrogenase content was assessed using the assay kit. Myeloperoxidase activity was determined using an assay. Histology of lung tissue was further analyzed through hematoxylin-eosin staining.

RESULTS

We found that TREM1 knockdown by transfection with si-TREM1 inhibited lipopolysaccharide (LPS)-induced cell apoptosis of alveolar macrophage cell line MH-S. The LPS stimulation caused M1 polarization of MH-S cells, which could be reversed by TREM1 knockdown. In vivo assays proved that si-TREM1 injection improved lung injury and inflammation of cecal ligation and puncture-induced ALI in mice. In addition, TREM1 knockdown suppressed the activation of toll-like receptor 4/nuclear factor-kappa B signaling, implying the involvement of TLR4 in the effects of TREM1 in response to LPS stimulation.

CONCLUSIONS

This study examined the proinflammatory role of TREM1 in septic ALI and its regulatory effect on alveolar macrophage polarization. These results suggest that TREM1 could potentially serve as a therapeutic target in the prevention and treatment of ALI.

Fuzhengjiedu formula exerts protective effect against LPS-induced acute lung injury via gut-lung axis

BACKGROUND

Acute lung injury (ALI) is distinguished by rapid and severe respiratory distress and prolonged hypoxemia. A traditional Chinese medicine (TCM), known as the Fuzhengjiedu formula (FZJDF), has been shown to have anti-inflammatory benefits in both clinical and experimental studies. The precise underlying processes, nevertheless, are yet unclear.

PURPOSE

This study sought to enlighten the protective mechanism of FZJDF in ALI through the standpoint of the gut-lung crosstalk.

METHODS

The impact of FZJDF on lipopolysaccharide (LPS)-induced ALI murine model were investigated, and the lung injury score, serum interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) expression were measured to confirm its anti-inflammatory effects. Additionally, gut microbiota analysis and serum and fecal samples metabolomics were performed using metagenomic sequencing and high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry, respectively.

RESULTS

FZJDF significantly induced histopathological changes caused by LPS-induced ALI as well as downregulated the serum concentration of IL-1β and TNF-α. Furthermore, FZJDF had an effect in gut microbiota disturbances, and linear discriminant effect size analysis identified signal transduction, cell motility, and amino acid metabolism as the potential mechanisms of action in the FZJDF-treated group. Several metabolites in the LPS and FZJDF groups were distinguished by untargeted metabolomic analysis. Correlations were observed between the relative abundance of microbiota and metabolic products. Comprehensive network analysis revealed connections among lung damage, gut microbes, and metabolites. The expression of glycine, serine, glutamate, cysteine, and methionine in the lung and colon tissues was dysregulated in LPS-induced ALI, and FZJDF reversed these trends.

CONCLUSION

This study revealed that FZJDF considerably protected against LPS-induced ALI in mice by regulating amino acid metabolism via the gut-microbiota-lung axis and offered thorough and in-depth knowledge of the multi-system linkages of systemic illnesses.

Lung protection of Chimonanthus nitens Oliv. essential oil driven by the control of intestinal disorders and dysbiosis through gut-lung crosstalk

This work aimed to investigate whether Chimonanthus nitens Oliv. essential oil (CEO)-mediated lung protection was implicated in gut-lung crosstalk. Results showed that CEO attenuated lung and intestinal impairment by improving histopathological changes and inhibiting TLR4/NF-κB signaling pathway in LPS-stimulated rats, suggesting that there might be a mechanism for its lung protection involved in gut-lung interaction through manipulating the overlap in pathological changes via the similar inflammatory response. Furthermore, CEO-triggered intestinal protection was in parallel with the mitigation of ROS production, apoptosis, Ca2+ transport and mitochondrial membrane potential loss in vivo, and its intestinal protection was confirmed in vitro through IEC-6 cells. Importantly, a combination with CEO and LPS significantly remodeled gut microbiota composition compared with LPS alone in rats, while no significant impact on lung microbiota. Therefore, CEO-exerted lung protection was linked to gut and lung interactions involvement with the control of intestinal disorders and dysbiosis.

Mechanism of exosomes from adipose-derived mesenchymal stem cells on sepsis-induced acute lung injury by promoting TGF-β secretion in macrophages

OBJECTIVE

Acute lung injury (ALI) caused by sepsis is a life-threatening condition characterized by uncontrollable lung inflammation. The current study sought to investigate the mechanism of adipose-derived mesenchymal stem cell-derived exosomes (ADMSC-Exos) in attenuating sepsis-induced ALI through TGF-β secretion in macrophages.

METHODS

Adipose-derived mesenchymal stem cell-derived exosomes (ADMSC-Exos) were extracted from ADMSCs and identified. Septic ALI mouse models were established via cecal ligation and puncture (CLP), followed by administration of ADMSC-Exos or sh-TGF-β lentiviral vector. Mouse macrophages (cell line RAW 264.7) were treated with lipopolysaccharide (LPS), co-cultured with Exos and splenic T cells, and transfected with TGF-β siRNA. The lung injury of CLP mice was evaluated, and levels of inflammatory indicators and macrophage markers were measured. The localization of macrophage markers and TGF-β was determined, and the level of TGF-β in lung tissues was measured. The effect of TGF-β knockdown on sepsis-induced ALI in CLP mice was evaluated, and the percentages of CD4+CD25+Foxp3+ Tregs in mononuclear cells/macrophages and Foxp3 levels in lung tissues/co-cultured splenic T cells were examined.

RESULTS

ADMSC-Exos were found to alleviate sepsis-induced ALI, inhibit inflammatory responses, and induce macrophages to secrete TGF-β in CLP mice. TGF-β silencing reversed the alleviating effect of ADMSC-Exos on sepsis-induced ALI. ADMSC-Exos also increased the number of Tregs in the spleen of CLP mice and promoted M2 polarization and TGF-β secretion in LPS-induced macrophages. After knockdown of TGF-β in macrophages in the co-culture system, the number of Tregs decreased, suggesting that ADMSC-Exos increased the Treg number by promoting macrophages to secrete TGF-β.

CONCLUSION

Our findings suggest ADMSC-Exos can effectively alleviate sepsis-induced ALI in CLP mice by promoting TGF-β secretion in macrophages.

Lactobacillus reuteri Ameliorates Lipopolysaccharide-Induced Acute Lung Injury by Modulating the Gut Microbiota in Mice

Acute lung injury (ALI) causes lung inflammation and edema as well as resulting in gut microbiota disorder. Probiotics, however, can improve the gut microbiota composition and modulate its immune response, playing an important role in ALI pathogenesis. Therefore, our study aims to investigate the effect of Lactobacillus reuteri on Lipopolysaccharide (LPS)-induced ALI in mice and to probe the mechanism of its synergistic modulatory effect on the lungs and intestines. We assessed the therapeutic effects of L. reuteri in the ALI mouse model by histopathology, alveolar lavage fluid and serum inflammatory factor analysis and explored microbiome and transcriptome alterations. L. reuteri intervention effectively attenuated lung tissue injury and significantly reduced the LPS-induced inflammatory response and macrophage and neutrophil infiltration. Additionally, L. reuteri improved the intestinal barrier function and remodeled the disordered microbiota. In conclusion, our study showed that L. reuteri attenuated the inflammatory response, ameliorated the pulmonary edema, repaired the intestinal barrier, and remodeled the gut microbiota in ALI mice. This study provides new perspectives on the clinical treatment of ALI.

Systemic cytokines inhibition with Imp7 siRNA nanoparticle ameliorates gut injury in a mouse model of ventilator-induced lung injury

Mechanical ventilation (MV) may negatively affect the lungs and cause the release of inflammatory mediators, resulting in extra-pulmonary organ dysfunction. Studies have revealed systemically elevated levels of proinflammatory cytokines in animal models of ventilator-induced lung injury (VILI); however, whether these cytokines have an effect on gut injury and the mechanisms involved remain unknown. In this study, VILI was generated in mice with high tidal volume mechanical ventilation (20 ml/kg). Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6 concentrations in serum and gut measured by ELISA showed significant elevation in the VILI mice. Significant increases in gut injury and PANoptosis were observed in the VILI mice, which were positively correlated with the serum levels of TNF-α, IL-1β, and IL-6. The VILI mice displayed intestinal barrier defects, decreased expressions of occludin and zonula occludin-1 (ZO-1), and increased expression of claudin-2 and the activation of myosin light chain (MLC). Importantly, intratracheal administration of Imp7 siRNA nanoparticle effectively inhibited cytokines production and protected mice from VILI-induced gut injury. These data provide evidence of systemic cytokines contributing to gut injury following VILI and highlight the possibility of targeting cytokines inhibition via Imp7 siRNA nanoparticle as a potential therapeutic intervention for alleviating gut injury following VILI.

Rgl-exomiR-7972, a novel plant exosomal microRNA derived from fresh Rehmanniae Radix, ameliorated lipopolysaccharide-induced acute lung injury and gut dysbiosis

Plant-derived exosome-like nanoparticles (ELNs) have been proposed as a novel therapeutic tool for preventing human diseases. However, the number of well-verified plant ELNs remains limited. In this study, the microRNAs in ELNs derived from fresh Rehmanniae Radix, a well-known traditional Chinese herb for treating inflammatory and metabolic diseases, were determined by using microRNA sequencing to investigate the active components in the ELNs and the protection against lipopolysaccharide (LPS)-induced acute lung inflammation in vivo and in vitro. The results showed that rgl-miR-7972 (miR-7972) was the main ingredient in ELNs. It exerted stronger protective activities against LPS-induced acute lung inflammation than catalpol and acteoside, which are two well-known chemical markers in this herb. Moreover, miR-7972 decreased the production of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α), reactive oxygen species (ROS) and nitric oxide (NO) in LPS-exposed RAW264.7 cells, thereby facilitating M2 macrophage polarization. Mechanically, miR-7972 downregulated the expression of G protein-coupled receptor 161 (GPR161), activating the Hedgehog pathway, and inhibited the biofilm form of Escherichia coli via targeting virulence gene sxt2. Therefore, miR-7972 derived from fresh R. Radix alleviated LPS-induced lung inflammation by targeting the GPR161-mediated Hedgehog pathway, recovering gut microbiota dysbiosis. It also provided a new direction for gaining novel bioactivity nucleic acid drugs and broadening the knowledge on cross-kingdom physiological regulation through miRNAs.

Ficolin A knockout alleviates sepsis-induced severe lung injury in mice by restoring gut Akkermansia to inhibit S100A4/STAT3 pathway

Acute lung injury (ALI) is a life-threatening disease with high morbidity and mortality. Our previous results demonstrated that Ficolin A (FcnA) protected against lipopolysaccharide (LPS)-induced mild ALI via activating complement, however the mechanism of severe lung damage caused by sepsis remains unclear. This study aimed to investigate whether FcnA modulated gut microbiota to affect the progression of sepsis-induced severe ALI. Fcna^-/- and Fcnb^-/- C57BL/6 mice were applied to establish the ALI model by injection of LPS intraperitoneally. Mice were treated with antibiotics, fecal microbiota transplantation (FMT), and intratracheal administration of recombinant protein S100A4. Changes in body weight of mice were recorded, and lung injury were assessed. Then lung tissue wet/dry weight was calculated. We found knockout of FcnA, but not FcnB, alleviated sepsis-induced severe ALI evidenced by increased body weight change, decreased wet/dry weight of lung tissue, reduced inflammatory infiltration, decreased lung damage score, decreased Muc-2, TNF-α, IL-1β, IL-6, and Cr levels, and increased sIgA levels. Furthermore, knockout of FcnA restored gut microbiota homeostasis in mice. Correlation analysis showed that Akkermansia was significantly negatively associated with TNF-α, IL-1β, and IL-6 levels in serum and bronchoalveolar lavage fluid (BALF). Moreover, knockout of FcnA regulated gut microbiota to protect ALI through S100A4. Finally, we found knockout of FcnA alleviated ALI by inhibiting S100A4 via gut Akkermansia in mice, which may provide further insights and new targets into treating sepsis-induced severe lung injury.

RNF128 regulates neutrophil infiltration and myeloperoxidase functions to prevent acute lung injury

Acute lung injury (ALI) is characterised by severe pulmonary inflammation, alveolar-capillary barrier disruption, and pulmonary oedema. Therefore, establishing effective therapeutic targets for ALI prevention is crucial. The present study reports a novel function of RNF128 in regulating LPS-induced ALI. Severe lung damage and increased immune cell infiltration were detected in RNF128-deficient mice. In vitro experiments revealed that RNF128 inhibits neutrophil activation by binding to myeloperoxidase (MPO) and reducing its levels and activity. Moreover, RNF128 regulates alveolar macrophage activation and neutrophil infiltration by interacting with TLR4, targeting it for degradation, and inhibiting NF-κB activation, hence decreasing pro-inflammatory cytokines. Our results demonstrate for the first time that RNF128 is a negative regulator of MPO and TLR4 in neutrophils and alveolar macrophages, respectively. However, AAV9-mediated RNF128 overexpression alleviated lung tissue damage and reduced inflammatory cell infiltration. Thus, RNF128 is a promising therapeutic candidate for pharmacological interventions in ALI.

miR-126-5p expression in the plasma of patients with sepsis-induced acute lung injury and its correlation with inflammation and immune function

OBJECTIVE

This work was implemented to elucidate the miR-126-5p expression in the plasma of patients with sepsis-induced acute lung injury (ALI) and its correlation with inflammation and immune function.

METHODS

The peripheral blood of patients with sepsis-induced ALI was obtained, and the levels of inflammatory factors (interleukin-6 [IL-6], C-reactive protein [CRP], and procalcitonin [PCT]) were determined. Meanwhile, T lymphocyte subsets (CD3+, CD4+, and CD8+), and immunoglobulins (IgA, IgM, and IgG) were tested. miR-126-5p and TRAF6 mRNA expression in plasma was assessed. Receiver operating characteristic (ROC) curve was performed to assess the diagnostic accuracy of miR-126-5p in sepsis without ALI and sepsis with ALI. Correlation between miR-126-5p expression and clinical indicators was analyzed. The targets of miR-126-5p were predicted using the bioinformatics method, and the direct targets were verified through investigations.

RESULTS

miR-126-5p expression in plasma of patients with sepsis-induced ALI was reduced than that of patients with sepsis without ALI. miR-126-5p expression was negatively correlated with IL-6, CRP, and PCT but positively correlated with IgA, IgM, and IgG as well as CD3+, CD4+, and CD8+ in patients with sepsis-induced ALI. ROC curve suggested that miR-126-5p (AUC: 0.777; 95%CI: 0.689-0.866) could distinguish patients with sepsis with ALI from patients with sepsis without ALI. TRAF6 expression in patients with sepsis-induced ALI was higher than that in patients with sepsis without ALI. TRAF6 was a target gene of miR-126-5p, CONCLUSION: This research highlights that miR-126-5p is reduced in the plasma of patients with sepsis-induced ALI, and miR-126-5p relates to systemic inflammation and immune function indicators.

Circulating sepsis-related metabolite sphinganine could protect against intestinal damage during sepsis

Introduction

Sepsis is intricately linked to intestinal damage and barrier dysfunction. At present times, there is a growing interest in a metabolite-based therapy for multiple diseases.

Methods

Serum samples from septic patients and healthy individuals were collected and their metabonomics profiling assessed using Ultra-Performance Liquid Chromatography-Time of Flight Mass Spectrometry (UPLC-TOFMS). The eXtreme Gradient Boosting algorithms (XGBOOST) method was used to screen essential metabolites associated with sepsis, and five machine learning models, including Logistic Regression, XGBoost, GaussianNB(GNB), upport vector machines(SVM) and RandomForest were constructed to distinguish sepsis including a training set (75%) and validation set(25%). The area under the receiver-operating characteristic curve (AUROC) and Brier scores were used to compare the prediction performances of different models. Pearson analysis was used to analysis the relationship between the metabolites and the severity of sepsis. Both cellular and animal models were used to HYPERLINK "javascript:;" assess the function of the metabolites.

Results

The occurrence of sepsis involve metabolite dysregulation. The metabolites mannose-6-phosphate and sphinganine as the optimal sepsis-related variables screened by XGBOOST algorithm. The XGBoost model (AUROC=0.956) has the most stable performance to establish diagnostic model among the five machine learning methods. The SHapley Additive exPlanations (SHAP) package was used to interpret the XGBOOST model. Pearson analysis reinforced the expression of Sphinganine, Mannose 6-phosphate were positively associated with the APACHE-II, PCT, WBC, CRP, and IL-6. We also demonstrated that sphinganine strongly diminished the LDH content in LPS-treated Caco-2 cells. In addition, using both in vitro and in vivo examination, we revealed that sphinganine strongly protects against sepsis-induced intestinal barrier injury.

Discussion

These findings highlighted the potential diagnostic value of the ML, and also provided new insight into enhanced therapy and/or preventative measures against sepsis.

The leaky gut and the gut microbiome in sepsis - targets in research and treatment

Both a leaky gut (a barrier defect of the intestinal surface) and gut dysbiosis (a change in the intestinal microbial population) are intrinsic to sepsis. While sepsis itself can cause dysbiosis, dysbiosis can worsen sepsis. The leaky gut syndrome refers to a status with which there is an increased intestinal permeability allowing the translocation of microbial molecules from the gut into the blood circulation. It is not just a symptom of gastrointestinal involvement, but also an underlying cause that develops independently, and its presence could be recognized by the detection, in blood, of lipopolysaccharides and (1→3)-β-D-glucan (major components of gut microbiota). Gut-dysbiosis is the consequence of a reduction in some bacterial species in the gut microbiome, as a consequence of intestinal mucosal immunity defect, caused by intestinal hypoperfusion, immune cell apoptosis, and a variety of enteric neuro-humoral-immunity responses. A reduction in bacteria that produce short-chain fatty acids could change the intestinal barriers, leading to the translocation of pathogen molecules, into the circulation where it causes systemic inflammation. Even gut fungi might be increased in human patients with sepsis, even though this has not been consistently observed in murine models of sepsis, probably because of the longer duration of sepsis and also antibiotic use in patients. The gut virobiome that partly consists of bacteriophages is also detectable in gut contents that might be different between sepsis and normal hosts. These alterations of gut dysbiosis altogether could be an interesting target for sepsis adjuvant therapies, e.g., by faecal transplantation or probiotic therapy. Here, current information on leaky gut and gut dysbiosis along with the potential biomarkers, new treatment strategies, and future research topics are mentioned.

Liquiritin exhibits anti-acute lung injury activities through suppressing the JNK/Nur77/c-Jun pathway

BACKGROUND

Licorice (Glycyrrhiza uralensis Fisch.), a well-known traditional medicine, is traditionally used for the treatment of respiratory disorders, such as cough, sore throat, asthma and bronchitis. We aim to investigate the effects of liquiritin (LQ), the main bioactive compound in licorice against acute lung injury (ALI) and explore the potential mechanism.

METHODS

Lipopolysaccharide (LPS) was used to induce inflammation in RAW264.7 cells and zebrafish. Intratracheal instillation of 3 mg/kg of LPS was used for induction an ALI mice model. The concentrations of IL-6 and TNF-α were tested using the enzyme linked immunosorbent assay. Western blot analysis was used to detect the expression of JNK/Nur77/c-Jun related proteins. Protein levels in bronchoalveolar lavage fluid (BALF) was measured by BCA protein assay. The effect of JNK on Nur77 transcriptional activity was determined by luciferase reporter assay, while electrophoretic mobility shift assay was used to examine the c-Jun DNA binding activity.

RESULTS

LQ has significant anti-inflammatory effects in zebrafish and RAW264.7 cells. LQ inhibited the expression levels of p-JNK (Thr183/Tyr185), p-Nur77 (Ser351) and p-c-Jun (Ser63), while elevated the Nur77 expression level. Inhibition of JNK by a specific inhibitor or small interfering RNA enhanced the regulatory effect of LQ on Nur77/c-Jun, while JNK agonist abrogated LQ-mediated effects. Moreover, Nur77-luciferase reporter activity was suppressed after JNK overexpression. The effects of LQ on the expression level of c-Jun and the binding activity of c-Jun with DNA were attenuated after Nur77 siRNA treatment. LQ significantly ameliorated LPS-induced ALI with the reduction of lung water content and BALF protein content, the downregulation of TNF-α and IL-6 levels in lung BALF and the suppression of JNK/Nur77/c-Jun signaling, which can be reversed by a specific JNK agonist.

CONCLUSION

Our results indicated that LQ exerts significant protective effects against LPS-induced inflammation both in vivo and in vitro via suppressing the activation of JNK, and consequently inhibiting the Nur77/c-Jun signaling pathway. Our study suggests that LQ may be a potential therapeutic candidate for ALI and inflammatory disorders.

Protective effects of Descurainia sophia seeds extract and its fractions on pulmonary edema by untargeted urine and serum metabolomics strategy

Background: Descurainia sophia seeds (DS) is a herbal medicine in traditional Chinese medicine (TCM) for treating lung diseases. We aimed to evaluate the therapeutic effect of DS and five of its fractions upon pulmonary edema (PE) through metabolomics analysis (MA) of urine and serum samples of rats. Methods: A PE model was established by intrathoracic injection of carrageenan. Rats were pretreated with DS extract or its five fractions (polysaccharides (DS-Pol); oligosaccharides (DS-Oli); flavonoid glycosides (DS-FG); flavonoid aglycone (DS-FA); fat oil fraction (DS-FO)) for seven consecutive days. Forty-eight hours after carrageenan injection, lung tissues were subjected to histopathology. MA of urine and serum was done by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry, respectively. Principal component analysis and orthogonal partial least squares-discriminant analysis were operated for the MA of rats and potential biomarkers related to treatment. Heatmaps and metabolic networks were constructed to explore how DS and its five fractions act against PE. Results: DS and its five fractions could all attenuate pathologic lung injury to different degrees, and DS-Oli, DS-FG, and DS-FO had a more potent effect compared with DS-Pol and DS-FA. DS-Oli, DS-FG, DS-FA, and DS-FO could regulate the metabolic profiles of PE rats, but DS-Pol was less potent. According to MA, the five fractions could improve PE to some degree due to their anti-inflammatory, immunoregulatory, and renoprotective activities by mediating the metabolism of taurine, tryptophan, and arachidonic acid. However, DS-Oli, DS-FG, and DS-FO had more important roles in edema-fluid reabsorption, and reduction of vascular leakage through regulating the metabolism of phenylalanine, sphingolipid and bile acid. Finally, heatmaps and hierarchical clustering analysis indicated DS-Oli, DS-FG, and DS-FO to be more efficacious than DS-Pol or DS-FA against PE. The five fractions of DS had a synergistic effect on PE from different aspects, thereby constituting the entire efficacy of DS. DS-Oli, DS-FG, or DS-FO could be used as an alternative to DS. Conclusion: MA combined with use of DS and its fractions provided novel insights into the mechanism of action of TCM.

Mechanism of miR-338-3p in sepsis-induced acute lung injury via indirectly modulating ATF4

Sepsis is recognized as an inflammation-related syndrome in response to invading pathogens. Many patients suffer from sepsis including transplant recipients. Lipopolysaccharide (LPS) is known to trigger sepsis-related organ dysfunction. This study expounded on the possible effect of microRNA (miR)-338-3p in sepsis-induced acute lung injury (ALI). Firstly, human bronchial epithelial cell line 16HBE received LPS treatment to establish the cell models of sepsis-induced ALI. The expression patterns of miR-338-3p, long non-coding RNA OPA-interacting protein 5 antisense transcript 1 (lncRNA OIP5-AS1), and activating transcription factor 4 (ATF4) in 16HBE cells were examined. Afterwards, 16HBE cell viability, the apoptosis rate, and the levels of inflammation and lactate dehydrogenase (LDH) were determined to assess the degree of cell injury. We disclosed that LPS treatment triggered 16HBE cell injury, downregulated miR-338-3p, and upregulated OIP5-AS1 and ATF4. miR-338-3p overexpression repressed LPS-induced 16HBE cell injury. miR-338-3p diminished OIP5-AS1 stability via binding to OIP5-AS1 and downregulated OIP5-AS1 expression and OIP5-AS1 can enhance ATF4 mRNA stability and upregulate ATF4 mRNA level. The rescue experiments showed that ATF4 overexpression aggravated LPS-induced 16HBE cell injury. Overall, miR-338-3p overexpression decreased OIP5-AS1 expression and stability and further downregulated ATF4 mRNA level, thereby mitigating LPS-induced 16HBE cell injury.

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 exaggerates multiple organ injury, inflammation, and immune cell imbalance by activating the NF-κB pathway in sepsis

Objective

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) modulates the inflammatory immune response and organ dysfunction, which are closely implicated in sepsis pathogenesis and progression. This study aimed to explore the role of MALT1 in sepsis-induced organ injury, immune cell dysregulation, and inflammatory storms.

Methods

Septic mice were constructed by intraperitoneal injection of lipopolysaccharide, followed by overexpression or knockdown of MALT1 by tail vein injection of the corresponding lentivirus. Mouse naïve CD4⁺ T cells and bone marrow-derived macrophages were treated with MALT1 overexpression/knockdown lentivirus plus lipopolysaccharide.

Results

In the lungs, livers, and kidneys of septic mice, MALT1 overexpression exaggerated their injuries, as shown by hematoxylin and eosin staining (all p < 0.05), elevated cell apoptosis, as reflected by the TUNEL assay and cleaved caspase-3 expression (p < 0.05 in the lungs and kidneys), and promoted macrophage infiltration, as illustrated by CD68 immunofluorescence (p < 0.05 in the lungs and kidneys). Meanwhile, in the blood, MALT1 overexpression reduced T-helper (Th)1/Th2 cells, increased Th17/regulatory T-cell ratios (both p < 0.05), promoted systematic inflammation, as revealed by tumor necrosis factor-α, interleukin-6, interleukin-1β, and C-reactive protein (all p < 0.05), elevated oxidative stress, as shown by nitric oxide (p < 0.05), superoxide dismutase, and malondialdehyde (p < 0.05), and enhanced liver and kidney dysfunction, as revealed by an automatic animal biochemistry analyzer (all p < 0.05 except for aspartate aminotransferase). However, MALT1 knockdown exerted the opposite effect as MALT1 overexpression. Ex vivo experiments revealed that MALT1 overexpression promoted the polarization of M1 macrophages and naïve CD4⁺ T cells toward Th2 and Th17 cells (all p < 0.05), while MALT1 knockdown attenuated these effects (all p < 0.05). Mechanistically, MALT1 positively regulated the nuclear factor-κB (NF-κB) pathway both in vivo and ex vivo (p < 0.05).

Conclusion

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 amplifies multiple organ injury, inflammation, oxidative stress, and imbalance of macrophages and CD4⁺ T cells by activating the NF-κB pathway in sepsis.

Altered gut microbiota in the early stage of acute pancreatitis were related to the occurrence of acute respiratory distress syndrome

Background

Acute respiratory distress syndrome (ARDS) is the most common cause of organ failure in acute pancreatitis (AP) patients, which associated with high mortality. Specific changes in the gut microbiota have been shown to influence progression of acute pancreatitis. We aimed to determine whether early alterations in the gut microbiota is related to and could predict ARDS occurrence in AP patients.

Methods

In this study, we performed 16S rRNA sequencing analysis in 65 AP patients and 20 healthy volunteers. The AP patients were further divided into two groups: 26 AP-ARDS patients and 39 AP-nonARDS patients based on ARDS occurrence during hospitalization.

Results

Our results showed that the AP-ARDS patients exhibited specific changes in gut microbiota composition and function as compared to subjects of AP-nonARDS group. Higher abundances of Proteobacteria phylum, Enterobacteriaceae family, Escherichia-Shigella genus, and Klebsiella pneumoniae, but lower abundances of Bifidobacterium genus were found in AP-ARDS group compared with AP-nonARDS groups. Random forest modelling analysis revealed that the Escherichia-shigella genus was effective to distinguish AP-ARDS from AP-nonARDS, which could predict ARDS occurrence in AP patients.

Conclusions

Our study revealed that alterations of gut microbiota in AP patients on admission were associated with ARDS occurrence after hospitalization, indicating a potential predictive and pathogenic role of gut microbiota in the development of ARDS in AP patients.

Upregulation of claudin‑4 by Chinese traditional medicine Shenfu attenuates lung tissue damage by acute lung injury aggravated by acute gastrointestinal injury

CONTEXT

Many studies have explored new methods to cure acute lung injury (ALI); however, none of those methods could significantly change the high mortality rate of ALI. Shenfu is a Chinese traditional medicine that might be effective against ALI.

OBJECTIVE

Our study explores the therapeutic potential of Shenfu in ALI.

MATERIALS AND METHODS

Male C57BL/6 mice were assigned to control, lipopolysaccharide (LPS) (500 µg/100 μL per mouse), and LPS + Shenfu (30 mL/kg) groups. Shenfu (10 µL/mL) was added to LPS (10 µg/mL) treated MLE-12 cells for 48 h in vitro. Male C57BL/6 mice were divided into four groups: LPS, LPS + 3% dextran sulphate sodium (DSS), 3% DSS + Shenfu, and LPS + 3% DSS + Shenfu.

RESULTS

Compared with the ALI group, Shenfu reduced wet/dry weight ratio (19.8%, 36.2%), and reduced the IL-2 (40.9%, 61.6%), IFN-γ (43.5%, 53.3%) TNF-α (54.1%, 42.1%), IL-6 (54.8%,70%), and IL-1β (39.9%, 65.1%), reduced serum uric acid (18.8%, 48.7%) and creatinine (17.4%, 41.1%). Moreover, Shenfu enhanced cell viability (17.2%, 59.9%) and inhibited cell apoptosis (63.0%) and p38/ERK phosphorylation in in vitro cultured epithelial cells with LPS stimulation. Mechanistically, Shenfu mediated the protective effect by upregulating claudin-4 expression. In addition, Shenfu could protect against both lung and intestinal epithelial damage in acute gastrointestinal injury-exacerbated ALI.

DISCUSSION AND CONCLUSIONS

Taken together, the results revealed the therapeutic effect and the underlying mechanism of Shenfu injection in an ALI in mouse model, indicating its clinical potential to treat patients with ALI.

Hydrogen Sulfide: A Gaseous Mediator and Its Key Role in Programmed Cell Death, Oxidative Stress, Inflammation and Pulmonary Disease

Hydrogen sulfide (H₂S) has been acknowledged as a novel gaseous mediator. The metabolism of H₂S in mammals is tightly controlled and is mainly achieved by many physiological reactions catalyzed by a suite of enzymes. Although the precise actions of H₂S in regulating programmed cell death, oxidative stress and inflammation are yet to be fully understood, it is becoming increasingly clear that H₂S is extensively involved in these crucial processes. Since programmed cell death, oxidative stress and inflammation have been demonstrated as three important mechanisms participating in the pathogenesis of various pulmonary diseases, it can be inferred that aberrant H₂S metabolism also functions as a critical contributor to pulmonary diseases, which has also been extensively investigated. In the meantime, substantial attention has been paid to developing therapeutic approaches targeting H₂S for pulmonary diseases. In this review, we summarize the cutting-edge knowledge on the metabolism of H₂S and the relevance of H₂S to programmed cell death, oxidative stress and inflammation. We also provide an update on the crucial roles played by H₂S in the pathogenesis of several pulmonary diseases. Finally, we discuss the perspective on targeting H₂S metabolism in the treatment of pulmonary diseases.

Tidy up - The unfolded protein response in sepsis

Pathogens, their toxic byproducts, and the subsequent immune reaction exert different forms of stress and damage to the tissue of the infected host. This stress can trigger specific transcriptional and post-transcriptional programs that have evolved to limit the pathogenesis of infectious diseases by conferring tissue damage control. If these programs fail, infectious diseases can take a severe course including organ dysfunction and damage, a phenomenon that is known as sepsis and which is associated with high mortality. One of the key adaptive mechanisms to counter infection-associated stress is the unfolded protein response (UPR), aiming to reduce endoplasmic reticulum stress and restore protein homeostasis. This is mediated via a set of diverse and complementary mechanisms, i.e. the reduction of protein translation, increase of protein folding capacity, and increase of polyubiquitination of misfolded proteins and subsequent proteasomal degradation. However, UPR is not exclusively beneficial since its enhanced or prolonged activation might lead to detrimental effects such as cell death. Thus, fine-tuning and time-restricted regulation of the UPR should diminish disease severity of infectious disease and improve the outcome of sepsis while not bearing long-term consequences. In this review, we describe the current knowledge of the UPR, its role in infectious diseases, regulation mechanisms, and further clinical implications in sepsis.

Acute Endotoxemia-Induced Respiratory and Intestinal Dysbiosis

Systemic inflammatory response syndrome (SIRS) is a severe condition characterized by systemic inflammation, which may lead to multiple organ failure, shock and death. SIRS is common in burn patients, pancreatitis and sepsis. SIRS is often accompanied by intestinal dysbiosis. However, the mechanism, role and details of microbiome alterations during the early phase of acute SIRS are not completely understood. The current study aimed to characterize the dynamic alterations of both the intestinal and respiratory microbiome at two timepoints during the early phase of acute SIRS (4 and 8 h after LPS) and link these to the host response in a mouse model of a LPS-induced lethal SIRS. Acute SIRS had no effect on the microbiome in the large intestine but induced a rapid dysbiosis in the small intestine, which resembled the microbiome alterations commonly observed in SIRS patients. Later in the disease progression, a dysbiosis of the respiratory microbiome was observed, which was associated with the MMP9 expression in the lungs. Although similar bacteria were increased in both the lung and the small intestine, no evidence for a gut-lung translocation was observed. Gut dysbiosis is commonly observed in diseases involving inflammation in the gut. However, whether the inflammatory response associated with SIRS and sepsis can directly cause gut dysbiosis was still unclear. In the current study we provide evidence that a LPS-induced SIRS can directly cause dysbiosis of the small intestinal and respiratory microbiome.