Endogenous PGI2 signaling through IP inhibits neutrophilic lung inflammation in LPS-induced acute lung injury mice model

Gut microbiome and serum metabolome alterations associated with lactose intolerance (LI): a case‒control study and paired-sample study based on the American Gut Project (AGP)

Lactose intolerance (LI) is a prevalent condition characterized by gastrointestinal symptoms that arise following lactose consumption. Recent evidence suggests that the gut microbiome may influence lactose levels in the gut. However, there is limited understanding regarding the alterations in microbiota and metabolism between individuals with LI and non-LI. This study conducted a paired-sample investigation utilizing data from the American Gut Project (AGP) and performed metagenomic and untargeted metabolomic analyses in a Chinese cohort to explore the interaction between the gut microbiome and serum metabolites. In addition, fecal microbiota transplantation (FMT) experiments were conducted to further examine the impact of the LI-associated gut microbiome on inflammatory outcomes. We identified 14 microbial genera that significantly differed between LI and controls from AGP data. Using a machine learning approach, group separation was predicted based on seven species and nine metabolites in the Chinese cohort. Notably, increased levels of Escherichia coli in the LI group were negatively correlated with several metabolites, including PC (22:6/0:0), indole, and Lyso PC, while reduced levels of Faecalibacterium prausnitzii and Eubacterium rectale were positively correlated with indole and furazolidone. FMT-LI rats displayed visceral hypersensitivity and an altered gut microbiota composition compared to FMT-HC rats. Metagenomic and metabolomic analyses revealed an enrichment of MAPK signaling in LI, which was confirmed by FMT-LI rats showing higher expression of ERK and RAS, along with increased concentrations of proinflammatory cytokines. This study provides valuable insights into the disrupted microbial and metabolic traits associated with LI, emphasizing potential microbiome-based approaches for its prevention and treatment.

IMPORTANCE

Lactose intolerance (LI) is a prevalent condition characterized by gastrointestinal symptoms after lactose consumption due to a deficiency of lactase. There is limited understanding regarding the microbiota and metabolic alterations between individuals with LI and non-LI. This study represents the first exploration to investigate metagenomic and metabolomic signatures among subjects with lactose intolerance as far as our knowledge. We identified 14 microbial genera in the Western cohort and 7 microbial species, along with 9 circulating metabolites in the Chinese cohort, which significantly differed in LI patients. Metagenomic and metabolomic analyses revealed an enrichment of MAPK signaling in LI patients. This finding was confirmed by FMT-LI rats, exhibiting increased expression of ERK and RAS, along with higher concentrations of pro-inflammatory cytokines. Our study provides insights into the disrupted functional and metabolic traits of the gut microbiome in LI, highlighting potential microbiome-based approaches for preventing and treating LI.

Prostacyclin synthase deficiency exacerbates systemic inflammatory responses in lipopolysaccharide-induced septic shock in mice

OBJECTIVES

Sepsis is a systemic inflammatory disorder characterized by life-threateningorgan dysfunction resulting from a dysregulated host response to infection. Prostacyclin (PGI2) is a bioactive lipid produced by PGI synthase (PGIS) and is known to play important roles in inflammatory reactions as well as cardiovascular regulation. However, little is known about the roles of PGIS and PGI2 in systemic inflammatory responses such as septic shock.

METHODOLOGY

Systemic inflammation was induced by intraperitoneal injection of 5 mg/kg lipopolysaccharide (LPS) in wild type (WT) or PGIS knockout (KO) mice. Selexipag, a selective PGI2 receptor (IP) agonist, was administered 2 h before LPS injection and again given every 12 h for 3 days.

RESULTS

Intraperitoneal injection of LPS induced diarrhea, shivering and hypothermia. These symptoms were more severe in PGIS KO mice than in WT micqe. The expression of Tnf and Il6 genes was notably increased in PGIS KO mice. In contrast, over 95% of WT mice survived 72 h after the administration of LPS, whereas all of the PGIS KO mice had succumbed by that time. The mortality rate of LPS-administrated PGIS KO mice was improved by selexipag administration.

CONCLUSION

Our study suggests that PGIS-derived PGI2 negatively regulates LPS-induced symptoms via the IP receptor. PGIS-derived PGI2-IP signaling axis may be a new drug target for systemic inflammation in septic shock.

Roles of prostaglandins in immunosuppression

Prostaglandins (PGs) play a crucial and multifaceted role in various physiological processes such as intercellular signaling, inflammation regulation, neurotransmission, vasodilation, vasoconstriction, and reproductive functions. The diversity and biological significance of these effects are contingent upon the specific types or subtypes of PGs, with each PG playing a crucial role in distinct physiological and pathological processes. Particularly within the immune system, PGs are essential in modulating the function of immune cells and the magnitude and orientation of immune responses. Hence, a comprehensive comprehension of the functions PG signaling pathways in immunosuppressive regulation holds substantial clinical relevance for disease prevention and treatment strategies. The manuscript provides a review of recent developments in PG signaling in immunosuppressive regulation. Furthermore, the potential clinical applications of PGs in immunosuppression are also discussed. While research into the immunosuppressive effects of PGs required further exploration, targeted therapies against their immunosuppressive pathways might open new avenues for disease prevention and treatment.

Effects of ferulic acid on growth performance and intestinal oxidation indexes of Jilin white geese under lipopolysaccharide-induced oxidative stress

In geese breeding, due to the frequent influence of drugs and environmental and other factors, geese are extremely prone to oxidative stress, which adversely affects growth and development, geese meat quality, down production, and severely affects the development of the geese industry. Ferulic acid from plant extracts can be used as a feed additive, which is safe and non-toxic, and it can exert certain therapeutic effects on oxidative stress in geese. This experiment investigated the effect of ferulic acid on the growth performance, organs indices, and intestinal oxidative indices of Jilin white geese under lipopolysaccharide-induced oxidative stress. Geese were randomly divided into six groups: C (blank control), L (lipopolysaccharide control), F1 (60 mg/kg ferulic acid), F2 (120 mg/kg ferulic acid), F3 (180 mg/kg ferulic acid), and F4 (240 mg/kg ferulic acid). Groups L and F1-F4 were injected intraperitoneally with 0.5 mg/kg lipopolysaccharide and group C with an equivalent volume of normal saline on days 14,17 and 20, and 10 animals from each group were randomly selected for slaughter on day 21. The results showed that: 1) On day 14, the final body weight and average daily feed intake were significantly higher in group F3 than in group L, and on day 21, the final body weight was significantly higher in group F3 than in group L. 2) The thymus index was significantly higher in group F4 than in group L. 4) In the duodenum, MDA activity was reduced in group C compared with that in group L. 5) In the jejunum and ileum, MDA was significantly lower in group F3 than in group L. These results show that the addition of 180 mg/kg of ferulic acid to the diet can promote the growth of geese and alleviate the damage caused by oxidative stress in all intestinal segments.

Potential mouse models of coronavirus-related immune injury

Basic research for prevention and treatment of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues worldwide. In particular, multiple newly reported cases of autoimmune-related diseases after COVID-19 require further research on coronavirus-related immune injury. However, owing to the strong infectivity of SARS-CoV-2 and the high mortality rate, it is difficult to perform relevant research in humans. Here, we reviewed animal models, specifically mice with coronavirus-related immune disorders and immune damage, considering aspects of coronavirus replacement, viral modification, spike protein, and gene fragments. The evaluation of mouse models of coronavirus-related immune injury may help establish a standardised animal model that could be employed in various areas of research, such as disease occurrence and development processes, vaccine effectiveness assessment, and treatments for coronavirus-related immune disorders. COVID-19 is a complex disease and animal models cannot comprehensively summarise the disease process. The application of genetic technology may change this status.

The urinary lipid profile in cats with idiopathic cystitis

Although feline idiopathic cystitis (FIC) distresses of many cats, its pathogenesis is unknown and the diagnosis is challenging. Polyunsaturated fatty acids (PUFAs) are metabolized into various lipid mediators. Lipid mediators such as prostaglandins (PGs) modulate inflammation and many of them are excreted into the urine. Thus, the investigation of the urinary lipid profile may reveal pathogenesis and help diagnosis of FIC. We collected urine samples from five FIC cats by spontaneous urination and analyzed 158 types of lipid mediators in urines using liquid chromatography-mass spectrometry. The urinary levels of PUFAs were higher in FIC compared to those of the healthy group. The excretions of a major inflammatory mediator, PGD2, were less in FIC. Other well-known inflammatory mediators such as PGE2, PGI2, and their metabolites did not show a difference. In contrast, the levels of PGF2α and its 2 metabolites and PGF3α were higher in FIC. These results may provide new insights into the future management of cat FIC.

Pulmonary artery targeted therapy in treatment of COVID-19 related ARDS. Literature review

INTRODUCTION

The most grievous complication of the COVID-19 is the acute respiratory distress syndrome. A specific, rescue treatment for rapidly deteriorating patients should emerge to improve respiratory function and help patients to survive the most challenging period. Drugs used in targeted therapy of pulmonary arterial hypertension (PAH) appears to be suitable for this task and this article describes their potential for treatment of severe cases of COVID-19.

METHODS

The authors reviewed the following databases for randomized controlled trials, reviews and meta-analyses published up to July 2020: Pubmed, Scopus, Google Scholar, Cochrane Database and ClinicalKey. The authors included every study contributory to the assessment of the potential of drugs used in targeted PAH therapy in treatment of COVID-19.

RESULTS

Endothelin receptor antagonists, phosphodiesterase 5 inhibitors, riociguat and prostacyclin have proven ani-inflammatory effect and reduce pulmonary artery blood pressure, lung oedema and remodelling. Bosentan shows antiviral properties and sildenafil, as well as epoprostenol, inhibits apoptosis of lung epithelial cells. Among patients with lung lesions the decrease of pulmonary blood pressure can lead to increase of ventilation/perfusion mismatch and decrease of blood oxygenation.

CONCLUSIONS

Among all assessed drugs bosentan, sildenafil and epoprostenol appear to be most promising and a combination of these drugs should be considered due to synergism. The targeted PAH therapy in treatment of COVID-19 associated ARDS could be a useful tool saving lives of patients with severe SARS-CoV-2 infection, however, its introduction should be investigated and monitored very carefully as it can lead to transient deterioration of patient condition.

Prostaglandin I2 (PGI2) inhibits Brucella abortus internalization in macrophages via PGI2 receptor signaling, and its analogue affects immune response and disease outcome in mice

To date, the implications of prostaglandin I2 (PGI₂), a prominent lipid mediator for modulation of immune responses, has not been clearly understood in Brucella infection. In this study, we found that cyclooxygenase-2 (COX-2) was significantly expressed in both infected bone marrow-derived macrophages (BMMs) and RAW 264.7 cells. Prostaglandin I2 synthase (PTGIS) expression was not significantly changed, and PGI₂receptor (PTGIR) expression was downregulated in BMMs but upregulated in RAW 264.7 macrophages at late infection. Here, we presented that PGI₂, a COX-derived metabolite, was produced by macrophages during Brucella infection and its production was regulated by COX-2 and IL-10. We suggested that PGI₂ and selexipag, a potent PGI₂ analogue, inhibited Brucella internalization through IP signaling which led to down-regulation of F-actin polymerization and p38α MAPK activity. Administration with selexipag suppressed immune responses and resulted in a notable reduction in bacterial burden in spleen of Brucella-challenged mice. Taken together, our study is the first to characterize PGI₂ synthesis and its effect in evasion strategy of macrophages against Brucella infection.

The first report of prostacyclin and its physiological roles in insects

Prostaglandins (PGs) mediate physiological processes of insects as well as mammals. Prostaglandin I₂ (PGI₂) is a relatively well-known eicosanoid with potent hormone-like actions on various tissues of vertebrates, however, its presence and biosynthetic pathway have not been described in insects. This study demonstrated that fat bodies of the lepidopteran species, Spodoptera exigua, contained ~ 3.6 pg/g PGI₂. To identify its biosynthetic pathway, a PGI₂ synthase gene of S. exigua (Se-PGIS) was predicted from a transcriptome of S. exigua; 25.6% homology with human PGIS was demonstrated. Furthermore, a predicted three-dimensional structure of Se-PGIS was demonstrated to be 38.3% similar to the human PGIS ortholog, including catalytic residues. Se-PGIS was expressed in all developmental stages of S. exigua and most abundant larval and adult stages; immune challenging of larvae significantly up-regulated these expression levels. The inducible expression of Se-PGIS expression was followed by a greater than four-fold increase in the concentration of PGI₂ in fat bodies 10 h after immune challenge. RNA interference (RNAi) against Se-PGIS was performed by injecting double-stranded RNA (dsRNA). Under these RNAi conditions, cellular immune responses (e.g., hemocyte-spreading behavior, nodulation, phenoloxidase activity) were not affected by bacterial challenge. The addition of PGI₂ to larvae treated with an eicosanoid biosynthesis inhibitor did not rescue the immunosuppression. Interestingly, PGI₂ injection significantly suppressed nodule formation in response to bacterial challenge. In addition to the negative effect of PGI₂ against immunity, the Se-PGIS-RNAi treatment significantly interfered with immature development and severely impaired oocyte development in female adults; the addition of PGI₂ to RNAi-treated females significantly recovered oocyte development. Se-PGIS RNAi treatment also impaired male fertility by reducing fecundity after mating with untreated females. These results suggest that PGI₂ acts as a negative regulator of immune responses initiated by other factors and mediates S. exigua development and reproduction.

Lipopolysaccharide-Induced Acute Lung Injury Is Associated with Increased Ran-Binding Protein in Microtubule-Organizing Center (RanBPM) Molecule Expression and Mitochondria-Mediated Apoptosis Signaling Pathway in a Mouse Model

Background

Acute lung injury (ALI) is a severe and life-threatening disorder treated in intensive care units. This study aimed to determine molecules or associated signaling pathways that are involved in lipopolysaccharide (LPS)-induced inflammation in an ALI model.

Material/Methods

An ALI mouse model was established by administering LPS (25 mg/kg via intratracheal instillation). Thirty-two ALI mice were divided into Model-4 h, Model-8 h, Model-12 h, and Model-24 h groups, while another 8 mice without LPS treatment were assigned as the Control group. Hematoxylin-eosin (HE) staining was used to evaluate inflammation of lung tissues. Wet weight/dry weight (W/D) ratio and myeloperoxidase (MPO) activity of lung tissue in ALI mice were evaluated. Expressions of Bcl-2, Bcl-XL, Bak, Bax, cleaved caspase-3 (C-caspase-3), and Ran-binding protein in microtubule-organizing center (RanBPM) were determined using Western blot analysis.

Results

LPS administration caused obvious inflammatory cell infiltration of lung tissues in ALI mice. The W/D ratio of ALI mouse lung tissues was significantly higher in Model groups than in the Control group (p<0.05). MPO activity of ALI mice was remarkably higher in Model groups compared to the Control group (p<0.05). LPS-induced ALI model mice exhibited significantly higher levels of C-caspase 3 lung tissues compared to the Control group (p<0.05). LPS-induced ALI model mice had significantly lower Bcl-XL/Bcl-2 and remarkably higher Bak/Bax expression compared with the Control group (p<0.05). LPS-induced ALI model mice displayed obviously higher RanBPM expression than in the Control group (p<0.05).

Conclusions

Lipopolysaccharide-induced acute lung injury is associated with increased RanBPM molecule expression and with mitochondria-mediated apoptosis signaling pathway in a mouse model.

A current view of G protein-coupled receptor - mediated signaling in pulmonary hypertension: finding opportunities for therapeutic intervention

Pathological vascular remodeling is observed in various cardiovascular diseases including pulmonary hypertension (PH), a disease of unknown etiology that has been characterized by pulmonary artery vasoconstriction, right ventricular hypertrophy, vascular inflammation, and abnormal angiogenesis in pulmonary circulation. G protein-coupled receptors (GPCRs) are the largest family in the genome and widely expressed in cardiovascular system. They regulate all aspects of PH pathophysiology and represent therapeutic targets. We overview GPCRs function in vasoconstriction, vasodilation, vascular inflammation-driven remodeling and describe signaling cross talk between GPCR, inflammatory cytokines, and growth factors. Overall, the goal of this review is to emphasize the importance of GPCRs as critical signal transducers and targets for drug development in PH.