Activation of cannabinoid-2 receptor protects against Pseudomonas aeruginosa induced acute lung injury and inflammation

Gut microbiota contributes to protection against porcine deltacoronavirus infection in piglets by modulating intestinal barrier and microbiome

BACKGROUND

Gut microbiota plays a critical role in counteracting enteric viral infection. Our previous study demonstrated that infection of porcine deltacoronavirus (PDCoV) disturbs gut microbiota and causes intestinal damage and inflammation in piglets. However, the influence of gut microbiota on PDCoV infection remains unclear.

RESULTS

Firstly, the relationship between gut microbiota and disease severity of PDCoV infection was evaluated using 8-day-old and 90-day-old pigs. The composition of gut microbiota was significantly altered in 8-day-old piglets after PDCoV infection, leading to severe diarrhea and intestinal damage. In contrast, PDCoV infection barely affected the 90-day-old pigs. Moreover, the diversity (richness and evenness) of microbiota in 90-day-old pigs was much higher compared to the 8-day-old piglets, suggesting the gut microbiota is possibly associated with the severity of PDCoV infection. Subsequently, transplanting the fecal microbiota from the 90-day-old pigs to the 3-day-old piglets alleviated clinical signs of PDCoV infection, modulated the diversity and composition of gut microbiota, and maintained the physical and chemical barrier of intestines. Additionally, metabolomic analysis revealed that the fecal microbiota transplantation (FMT) treatment upregulated the swine intestinal arginine biosynthesis, FMT significantly inhibited the inflammatory response in piglet intestine by modulating the TLR4/MyD88/NF-κB signaling pathway.

CONCLUSIONS

PDCoV infection altered the structure and composition of the gut microbiota in neonatal pigs. FMT treatment mitigated the clinical signs of PDCoV infection in the piglets by modulating the gut microbiota composition and intestinal barrier, downregulating the inflammatory response. The preventive effect of FMT provides novel targets for the development of therapeutics against enteropathogenic coronaviruses. Video Abstract.

Activating Dectin-1/SOCS1 signaling attenuates pseudomonas aeruginosa-induced lung injury

OBJECTIVE

To investigate the role of Dectin-1 in alleviating Pseudomonas aeruginosa (PA)-induced lung injury and its underlying mechanism.

METHODS

Wild-type and Dectin-1 knockout (KO) C57BL/6 mice were exposed to PAvia intratracheal instillation. PAO1 strains were cultured, inactivated, and quantified. MHS cells were used in vitro. Curdlan was employed to activate Dectin-1 signaling, and SOCS1 expression was modulated through genetic manipulation. Levels of Dectin-1, Syk, p-Syk, SOCS1, p-p65, and p65 were assessed. Lung injury was evaluated using H&E and TUNEL staining, cell counts and protein content in bronchoalveolar lavage fluid (BALF), the lung tissue wet/dry ratio, and seven-day survival rates. Bacterial burden in the lung was assessed by PA colony formation. Inflammatory responses were measured by TNF-α, IL-6, and IL-1β levels in BALF, as well as the p-p65/p65 ratio in lung or cell lysates. Apoptosis rates in cells were determined by flow cytometry.

RESULTS

Dectin-1 expression was downregulated in the lungs and MHS cells following PA infection. Dectin-1 depletion exacerbated PA-induced lung injury. Activation of Dectin-1 by curdlan significantly alleviated PA-induced lung injury. PA infection reduced SOCS1 expression, and SOCS1 interference exacerbated the inflammatory response and apoptosis in MHS cells, nullifying the protective effects of curdlan. Overexpression of SOCS1 significantly reduced inflammation and apoptosis in both MHS cells and Dectin-1 KO mice.

CONCLUSIONS

Activation of Dectin-1 significantly mitigates PA-induced lung injury, with SOCS1 playing a critical role in this process.

Inflammaging and Immunosenescence in the Post-COVID Era: Small Molecules, Big Challenges

Aging naturally involves a decline in biological functions, often triggering a disequilibrium of physiological processes. A common outcome is the altered response exerted by the immune system to counteract infections, known as immunosenescence, which has been recognized as a primary cause, among others, of the so-called long-COVID syndrome. Moreover, the uncontrolled immunoreaction leads to a state of subacute, chronic inflammatory state known as inflammaging, responsible in turn for the chronicization of concomitant pathologies in a self-sustaining process. Anti-inflammatory and immunosuppressant drugs are the current choice for the therapy of inflammaging in post-COVID complications, with contrasting results. The increasing knowledge of the biochemical pathways of inflammaging led to disclose new small molecules-based therapies directed toward different biological targets involved in inflammation, immunological response, and oxidative stress. Herein, paying particular attention to recent clinical data and preclinical literature, we focus on the role of endocannabinoid system in inflammaging, and the promising therapeutic option represented by the CB2R agonists, the role of novel ligands of the formyl peptide receptor 2 and ultimately the potential of newly discovered monoamine oxidase (MAO) inhibitors with neuroprotective activity in the treatment of immunosenescence.

Cannabinoid receptor deficiencies drive immune response dynamics in Salmonella infection

This study investigated the roles of cannabinoid receptors 1 and 2 (CB1R and CB2R) in regulating host responses to Salmonella Typhimurium in C57BL/6 mice. The absence of both receptors significantly impaired host resilience, as evidenced by increased weight loss, deteriorated body condition, and reduced survival following infection. Notably, CB1R deficiency resulted in more pronounced weight loss and heightened susceptibility to bacterial proliferation, as demonstrated by increased Salmonella dissemination to organs. In addition, both CB1R and CB2R knockout mice exhibited alterations in immune cell recruitment and cytokine production. CB1R-KO mice displayed increased T cell and macrophage populations, whereas CB2R-KO mice showed a reduction in NK cells, indicating receptor-specific effects on immune cell mobilization. Cytokine profiling of macrophages post-infection revealed that CB1R-KO mice had reduced IL-10 levels, along with increased IL-6 and TGF-β, suggesting a dysregulated polarization state that combines pro-inflammatory and regulatory elements. In contrast, CB2R-KO mice exhibited a profile consistent with a more straightforward pro-inflammatory shift. Furthermore, microbiota analysis demonstrated that CB2R-KO mice experienced significant gut dysbiosis, including reduced levels of beneficial Lactobacillus and Bifidobacterium species and an increase in pro-inflammatory Alistipes species post-infection. Functional microbiome analysis further indicated declines in key metabolic pathways, such as the Bifidobacterium shunt, L-glutamine biosynthesis, and L-lysine biosynthesis, suggesting microbiota-driven immune dysregulation. Together, these findings highlight the distinct, non-redundant roles of CB1R and CB2R in modulating innate immunity, host defense, and microbiota composition during bacterial infections.

NAT10 induces mitochondrial dysfunction in lung epithelial cells by acetylating HMGB1 to exacerbate Pseudomonas aeruginosa-induced acute lung injury

BACKGROUND

Pseudomonas aeruginosa (PA) is a major pathogen that causes pneumonia and acute lung injury (ALI). Dysregulated NAT10 expression is associated with inflammatory and infectious diseases, but its role in PA-induced ALI remains unclear.

METHODS

A mouse pneumonia model was established by intratracheal injection of PA, and lentivirus-mediated NAT10 interference and HMGB1 overexpression vectors were administered via the tail vein. Lung mechanics, protein content, total cell counts, neutrophil counts, inflammatory factor levels in bronchoalveolar lavage fluid (BALF), and lung bacterial load were assessed 24 h after PA injection. HE staining was performed to evaluate lung structural damage. Intracellular oxidative stress levels in mouse lung epithelial cells (TC-1 cells) were measured by detecting ROS and MDA levels. Mitochondrial function was analyzed by testing the mitochondrial membrane potential, cytoplasmic accumulation of cytochrome C, mtDNA copy number, and ATP production. An N4-acetylcytidine (ac4C)-RNA immunoprecipitation assay was conducted to assess the ac4C level of HMGB1 mRNA.

RESULTS

NAT10 deficiency hindered PA infection-induced increases in immune cell infiltration, inflammatory factor levels, bacterial load, and ultimately lung structural and functional damage. However, upregulation of HMGB1 effectively antagonized the protective effects of NAT10 silencing in vivo. NAT10 knockdown suppressed PA-induced oxidative stress, mitochondrial dysfunction, and apoptosis in vitro. Whereas, HMGB1 overexpression reversed the inhibitory effects of NAT10 downregulation on PA-induced TC-1 cell injury. Mechanistically, as an acetyltransferase, NAT10 enhanced HMGB1 mRNA stability and protein expression by promoting HMGB1 mRNA ac4C modification.

CONCLUSION

NAT10 facilitated mitochondrial dysfunction in lung epithelial cells and exacerbated PA-induced ALI by promoting the N4-acetylcytidine of HMGB1 mRNA.

Cannabinoid-2 Receptor Activation Attenuates Sulfur Mustard Analog 2-Chloroethyl-Ethyl-Sulfide-Induced Acute Lung Injury in Mice

Background: Exposure to sulfur mustard (SM; 2,2'-dichlorodiethyl sulfide) causes toxicity in the human body, particularly the lungs. The molecular mechanisms of SM-induced lung damage are elusive, and no effective treatments exist. This study explores the anti-inflammatory potential of cannabinoid receptor 2 (CB2R) activation in mitigating acute lung injury (ALI) and inflammation induced by 2-chloroethyl ethyl sulfide (CEES), a structural analog of SM. Methods: C57BL/6J mice were exposed to CEES via intratracheal administration to model ALI. CB2R activation was achieved through the intraperitoneal administration of HU308, a selective synthetic agonist. ALI and inflammation were evaluated at 48 h post-exposure to CEES. Bronchoalveolar lavage fluid (BALF) was collected to measure total cells, protein, and cytokines. Lung injury, inflammatory signaling in alveolar macrophages (AMs), and matrix metalloproteinase-9 (MMP-9) activity were assessed via histological analysis, immunoblotting, and gelatin zymography, respectively. Results: CEES exposure led to an increase in immune cell infiltration, pro-inflammatory cytokines (IL-6 and TNF-α), and pro-MMP9 levels in the BALF, which were significantly decreased by HU308 treatment. The activation of CB2R attenuated CEES-induced NF-κB activation and reduced pro-inflammatory M1 markers (iNOS, and Cox-2) but did not alter the increase in the M2 marker arginase-1. CB2R activation mitigated CEES-induced oxidative stress, as evidenced by lower levels of heme oxygenase-1 (HO-1) and reactive oxygen species (ROS) in mouse AMs. Additionally, 4-hydroxynonenal (4-HNE) levels were reduced in the lungs of HU308-treated mice but were elevated after CEES exposure. Conclusions: These findings suggest that CB2R activation alleviates CEES-induced ALI and inflammation in mice, supporting its potential as a therapeutic approach for vesicant-induced pulmonary injury.

The impact of different gastrointestinal reconstruction techniques on gut microbiota after gastric cancer surgery

Introduction

Gastric cancer is one of the common malignant tumors in the digestive tract, characterized by high incidence and mortality rates. This is particularly significant in China, where a large proportion of global new cases of gastric cancer and related deaths occur. In recent years, with the continuous development of molecular biology technology, people have gained a deeper understanding of the gastrointestinal microbiome, and studies have shown that it is closely related to the occurrence, development, and therapeutic response of gastric cancer. Although surgical intervention is crucial in significantly extending the survival of gastric cancer patients, the disruption of the balance of the intestinal microbiota caused by surgery itself should not be overlooked, as it may affect postoperative recovery.

Methods

This study was approved by the Biomedical Ethics Committee of Sichuan Mianyang 404 Hospital. A random sampling method was used to select patients who underwent gastric cancer surgery at the hospital from January 2023 to December 2023. All patients signed written informed consent forms. Standardized perioperative management was conducted for the patients in the study, including preoperative preparation, intraoperative handling, and postoperative treatment. Fecal samples were collected from patients before surgery (before bowel preparation) and around one week after surgery for 16S rRNA sequencing analysis, through which differential biomarkers and related functional genes were sought.

Results

The study results indicated that there was no significant difference in the diversity of the gut microbiota between the two groups. Compared with the R-Y group, the DTR surgical method significantly altered the structure of the gut microbiota, affecting the types, quantities, and proportions of intestinal bacteria. Furthermore, the DTR group exhibited poorer postoperative nutritional absorption capacity compared to the R-Y group, as indicated by a lower F/B ratio. The R-Y group showed a richer abundance of Bacteroidetes and a lower abundance of Proteobacteria, as well as a higher F/B ratio after surgery. These findings provide new insights into the changes in the gut microbiota following gastric cancer surgery, which may be of significant importance for postoperative recovery and long-term health management.

Discussion

This study reveals the impact of different gastrointestinal reconstruction techniques on the postoperative gut microbiota of gastric cancer patients, providing new insights into the physiological changes during the postoperative recovery period. Although there was no significant difference in microbial diversity between the DTR group and the R-Y group, the DTR group showed more pronounced changes in microbial structure postoperatively, which may be associated with an increased risk of postoperative infection. These findings emphasize the importance of considering the impact on the gut microbiota when selecting gastric cancer surgery methods. However, the study had a limited sample size and did not delve into changes in metabolites. Future studies should expand the sample size and conduct metabolomic analyses to further validate these preliminary findings.

The intricate interactions between inflammasomes and bacterial pathogens: Roles, mechanisms, and therapeutic potentials

Inflammasomes are intracellular multiprotein complexes that consist of a sensor, an adaptor, and a caspase enzyme to cleave interleukin (IL)-1β and IL-18 into their mature forms. In addition, caspase-1 and -11 activation results in the cleavage of gasdermin D to form pores, thereby inducing pyroptosis. Activation of the inflammasome and pyroptosis promotes host defense against pathogens, whereas dysregulation of the inflammasome can result in various pathologies. Inflammasomes exhibit versatile microbial signal detection, directly or indirectly, through cellular processes, such as ion fluctuations, reactive oxygen species generation, and the disruption of intracellular organelle function; however, bacteria have adaptive strategies to manipulate the inflammasome by altering microbe-associated molecular patterns, intercepting innate pathways with secreted effectors, and attenuating inflammatory and cell death responses. In this review, we summarize recent advances in the diverse roles of the inflammasome during bacterial infections and discuss how bacteria exploit inflammasome pathways to establish infections or persistence. In addition, we highlight the therapeutic potential of harnessing bacterial immune subversion strategies against acute and chronic bacterial infections. A more comprehensive understanding of the significance of inflammasomes in immunity and their intricate roles in the battle between bacterial pathogens and hosts will lead to the development of innovative strategies to address emerging threats posed by the expansion of drug-resistant bacterial infections.

Exploring the versatile roles of the endocannabinoid system and phytocannabinoids in modulating bacterial infections

The endocannabinoid system (ECS), initially identified for its role in maintaining homeostasis, particularly in regulating brain function, has evolved into a complex orchestrator influencing various physiological processes beyond its original association with the nervous system. Notably, an expanding body of evidence emphasizes the ECS's crucial involvement in regulating immune responses. While the specific role of the ECS in bacterial infections remains under ongoing investigation, compelling indications suggest its active participation in host-pathogen interactions. Incorporating the ECS into the framework of bacterial pathogen infections introduces a layer of complexity to our understanding of its functions. While some studies propose the potential of cannabinoids to modulate bacterial function and immune responses, the outcomes inherently hinge on the specific infection and cannabinoid under consideration. Moreover, the bidirectional relationship between the ECS and the gut microbiota underscores the intricate interplay among diverse physiological processes. The ECS extends its influence far beyond its initial discovery, emerging as a promising therapeutic target across a spectrum of medical conditions, encompassing bacterial infections, dysbiosis, and sepsis. This review comprehensively explores the complex roles of the ECS in the modulation of bacteria, the host's response to bacterial infections, and the dynamics of the microbiome. Special emphasis is placed on the roles of cannabinoid receptor types 1 and 2, whose signaling intricately influences immune cell function in microbe-host interactions.

Cannabis effectiveness on immunologic potency of pulmonary contagion

Respiratory illnesses and its repercussions are becoming more prevalent worldwide. It is necessary to research both innovative treatment and preventative techniques. Millions of confirmed cases and fatalities from the COVID-19 epidemic occurred over the previous two years. According to the review research, cannabinoids are a class of medicines that should be considered for the treatment of respiratory conditions. Cannabinoids and inhibitors of endocannabinoid degradation have illustrated advantageous anti-inflammatory, asthma, pulmonary fibrosis, and pulmonary artery hypotension in numerous studies (in vitro and in vivo). It has been also noted that CB2 receptors on macrophages and T-helper cells may be particularly triggered to lower inflammation in COVID-19 patients. Since the majority of lung tissue contains cannabinoid receptors, cannabis can be an effective medical tool for treating COVID-19 as well as pulmonary infections. Notably, CB2 and CB1 receptors play a major role in immune system modulation and anti-inflammatory activities. In this review, we put forth the idea that cannabis might be helpful in treating pulmonary contagion brought on by viral integration, such as that caused by SARS-CoV-2, haemophilus influenza type b, Streptococcus pneumoniae, influenza virus, and respiratory syncytial virus. Also, a detailed overview of CB receptors, intricate mechanisms, is highlighted connecting link with COVID-19 viral structural modifications along with molecular basis of CB receptors in diminishing viral load in pulmonary disorders supported through evident literature studies. Further, futuristic evaluations on cannabis potency through novel formulation development focusing on in vivo/in vitro systems can produce promising results.

Baicalin ameliorates multidrug-resistant Pseudomonas aeruginosa induced pulmonary inflammation in rat via arginine biosynthesis

Multidrug-resistance (MDR) Pseudomonas aeruginosa (P. aeruginosa) is a lethal gram-negative pathogen causing hospital-acquired and ventilator-associated pneumonia, which is difficult to treat. Our previous studies confirmed that baicalin, an essential bioactive component in Scutellaria baicalensis Georgi, exhibited anti-inflammatory effects in an acute pneumonia rat model induced by MDR P. aeruginosa. However, this effect of baicalin in constrast its low bioavailability, and its mechanism of action is still unknown. Thus, this study investigated whether the therapeutic effects of baicalin against MDR P. aeruginosa acute pneumonia are owing to the regulation of gut microbiota and their metabolites using pyrosequencing of the 16S rRNA genes in rat feces and metabolomics. As a result, baicalin attenuated the inflammation by acting directly on neutrophils and regulated the production of the inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-10. The mechanisms were through down-regulation of TLR4 and inhibition of NF-κB. Furthermore, pyrosequencing of the 16S rRNA genes in rat feces revealed that baicalin regulated the composition of gut microbial communities. At the genus level, baicalin efficiently increased the abundance of Ligilactobacillus, Lactobacillus and Bacteroides, but decreased the abundance of Muribaculaceae and Alistipes. Further, arginine biosynthesis was analyzed as the core pathway regulated by baicalin via combination with predicting gut microbiota function and targeted metabolomics. In conclusion, this study has demonstrated that baicalin relieved inflammatory injury in acute pneumonia rat induced by MDR P. aeruginosa via arginine biosynthesis associated with gut microbiota. Baicalin could be a promising and effective adjunctive therapy for lung inflammation caused by MDR P. aeruginosa infection.