Combination of aspirin with essential fatty acids is superior to aspirin alone to prevent or ameliorate sepsis or ARDS

Carrimycin ameliorates lipopolysaccharide and cecal ligation and puncture-induced sepsis in mice

Carrimycin (CA), sanctioned by China's National Medical Products Administration (NMPA) in 2019 for treating acute bronchitis and sinusitis, has recently been observed to exhibit multifaceted biological activities, encompassing anti-inflammatory, antiviral, and anti-tumor properties. Despite these applications, its efficacy in sepsis treatment remains unexplored. This study introduces a novel function of CA, demonstrating its capacity to mitigate sepsis induced by lipopolysaccharide (LPS) and cecal ligation and puncture (CLP) in mice models. Our research employed in vitro assays, real-time quantitative polymerase chain reaction (RT-qPCR), and RNA-seq analysis to establish that CA significantly reduces the levels of pro-inflammatory cytokines, namely tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6), in response to LPS stimulation. Additionally, Western blotting and immunofluorescence assays revealed that CA impedes Nuclear Factor Kappa B (NF-κB) activation in LPS-stimulated RAW264.7 cells. Complementing these findings, in vivo experiments demonstrated that CA effectively alleviates LPS- and CLP-triggered organ inflammation in C57BL/6 mice. Further insights were gained through 16S sequencing, highlighting CA's pivotal role in enhancing gut microbiota diversity and modulating metabolic pathways, particularly by augmenting the production of short-chain fatty acids in mice subjected to CLP. Notably, a comparative analysis revealed that CA's anti-inflammatory efficacy surpasses that of equivalent doses of aspirin (ASP) and TIENAM. Collectively, these findings suggest that CA exhibits significant therapeutic potential in sepsis treatment. This discovery provides a foundational theoretical basis for the clinical application of CA in sepsis management.

Mendelian Randomization Analysis Reveals Causal Associations of Polyunsaturated Fatty Acids with Sepsis and Mortality Risk

INTRODUCTION

Despite numerous observational studies reporting a positive correlation between polyunsaturated fatty acids (PUFAs) and the risk of sepsis and mortality, the causation of such an association has yet to be firmly established. Thus, our study aimed to undertake the Mendelian randomization (MR) approach to scrutinize the potential causalities of PUFAs with sepsis and mortality risk.

METHODS

We conducted the MR investigation using genome-wide association study (GWAS) summary statistics of PUFAs [including omega-3 fatty acids (omega-3), omega-6 fatty acids (omega-6), the ratio of omega-6 to omega-3 fatty acids (omega-6:3), docosahexaenoic acid (DHA), linoleic acid (LA)], sepsis, and sepsis mortality. We utilized the GWAS summary data from the UK Biobank. To establish reliable causality, we employed the inverse-variance weighted (IVW) method as the primary analytical approach, together with four additional MR methods. In addition, we performed heterogeneity and horizontal pleiotropy assessments using Cochrane's Q test and MR-Egger intercept test, respectively. Finally, we performed a series of sensitivity analyses to enhance the precision and veracity of our findings.

RESULTS

The IVW method showed that genetically predicted omega-3 [odd ratio (OR) 0.914, 95% confidence interval (CI) 0.845-0.987, P = 0.023] and DHA (OR 0.893, 95% CI 0.815-0.979, P = 0.015) were suggestively linked to a decreased risk of sepsis. Furthermore, genetically predicted DHA (OR 0.819, 95% CI 0.681-0.986, P = 0.035) was suggestively associated with a reduced risk of sepsis-related death. Conversely, the omega-6:3 ratio (OR 1.177, 95% CI 1.011-1.371, P = 0.036) was suggestively linked to an increased risk of sepsis-induced mortality. On the basis of the MR-Egger intercept assessment, it appears that our MR examination was not influenced by any horizontal pleiotropy (all P > 0.05). Moreover, the reliability of the estimated causal association was confirmed by the sensitivity analyses.

CONCLUSION

Our study supported the casual effect between PUFAs and susceptibility to sepsis and sepsis-related death. Our findings underline the importance of specific PUFAs levels, particularly for individuals with a genetic susceptibility to sepsis. Further research is needed to confirm these findings and investigate the underlying mechanisms.

Lipoxin alleviates oxidative stress: a state-of-the-art review

OBJECTIVE

This review aims to summarize the capability of lipoxin in regulating oxidative stress.

BACKGROUND

Oxidative stress is defined as an imbalance between the production of free radicals and the antioxidant system, and it is associated with the existence of a large number of oxidation products, such as reactive oxygen species (ROS) and reaction nitrogen species (RNS), causing damage to human tissues through immunoinflammatory responses. Therefore, reducing oxidative stress is vital to alleviate pathological damage. Lipoxin, an acronym for lipoxygenase interaction product, is a bioactive autacoid metabolite of arachidonic acid made by various cell types. Previous studies have shown that lipoxin is associated with a variety of biological functions, including anti-inflammatory, regulating immune responses, promoting the repair of damaged cells, etc. The deficiency of lipoxin is a critical pathological mechanism in different diseases. Moreover, the ability of lipoxin to attenuate oxidative stress is noteworthy, thereby protecting the human body from diverse diseases.

METHODS

We searched papers from PubMed database using search terms, such as lipoxin, lipoxin A4, oxidative stress, and other relevant terms.

RESULTS

A total of 103 articles published over the past 20 years were identified for inclusion. We summarized the capability of lipoxin in regulating oxidative stress and mechanism.

CONCLUSION

Lipoxin is provided with a protective role in attenuating oxidative stress.

Classic Signaling Pathways in Alveolar Injury and Repair Involved in Sepsis-Induced ALI/ARDS: New Research Progress and Prospect

Sepsis is a common critical clinical disease with high mortality that can cause approximately 10 million deaths worldwide each year. Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is a common clinical complication of sepsis, which occurs primarily as diffuse alveolar injury, hypoxemia, and respiratory distress. The mortality rate of ALI/ARDS is as high as 30%-40%, which greatly endangers human health. Due to the unclear pathogenesis of ALI/ARDS, its treatment is still a worldwide problem. At present, clinical treatment mainly relies on lung-protective ventilation, prone position ventilation, and fluid management. However, there is a lack of effective and specific treatment measures. In recent years, domestic and foreign scholars have committed to basic research on ALI/ARDS, trying to further clarify its pathogenesis and find new targets and methods for the treatment of ALI/ARDS. In this review, we summarize the signaling pathways related to alveolar injury and repair in sepsis-induced ALI/ARDS and their latest research progress. They include the NF-κB, JAK2/STAT3, mitogen-activated protein kinase (MAPK), mTOR, and Notch signaling pathways. Understanding the molecular mechanisms of these signaling pathways in sepsis-induced ALI/ARDS may provide new targets and ideas for the clinical treatment of this disease.

Short-term protective effect of octreotide on the lungs of rats with experimentally induced sepsis

BACKGROUND

Acute respiratory distress syndrome is a devastating complication of severe sepsis. Preclinical models suggest that direct lung injury begins with attack to the lung epithelium, but indirect lung injury results from systemic endothelial damage due to inflammatory mediators. The aim of the present study was to explore the effect of octreotide on lungs in a surgically induced sepsis model in rats.

METHODS

We used 32 male Sprague Dawley rats and divided into four groups. Group 1: Normal (non-operative and orally fed control, n=8); Group 2: Sham operated (n=8); Group 3: Cecal ligation and puncture (CLP) (untreated group, n=8); and Group 4: CLP and 100 µg/kg octreotide i.p. (n=8). For sepsis, CLP procedure was performed on 16 rats to induce a sepsis model. All groups were analyzed, their blood was taken for arterial blood gas analysis. For histological examination, lung tissues were removed and sections were prepared.

RESULTS

In histological examination, if we compare CLP + Octreotide with only CLP group in CLP + Octreotide group decreased inflammatory cell infiltration in alveolar and interstitial area as well as edema, bleeding, when CLP group was compared with octreotide group, all histopathological parameters improved significantly and the severity index decreased from 3 to 1. For arterial blood gas, when CLP and octreotide groups were compared with CLP group, it was observed that there was a significant change in favor of healing and that they almost came up to controls and sham group.

CONCLUSION

It could be hypothesized that it would be beneficial to administer octreotide for ameliorate lung injury state in sepsis patients.

A high docosahexaenoic acid diet alters lung inflammation and recovery following repetitive exposure to aqueous organic dust extracts

Agricultural workers, especially those who work in swine confinement facilities, are at increased risk for developing pulmonary diseases including asthma, chronic obstructive pulmonary disease, and chronic bronchitis due to exposures to fumes, vapors, and organic dust. Repetitive exposure to agricultural dust leads to unresolved inflammation, a common underlying mechanism that worsens lung disease. Besides occupational exposure to dusts, diet also significantly contributes to inflammation and disease progression. Since DHA (docosahexaenoic acid), a polyunsaturated omega-3 fatty acid and its bioactive metabolites have key roles in inflammation resolution, we rationalized that individuals chronically exposed to organic dusts can benefit from dietary modifications. Here, we evaluated the role of DHA in modifying airway inflammation in a murine model of repetitive exposure to an aqueous extract of agricultural dust (three-week exposure to swine confinement dust extract, HDE) and after a one-week resolution/recovery period. We found that mice fed a high DHA diet had significantly increased bronchoalveolar lavage fluid (BALF) levels of DHA-derived resolvins and lower TNFα along with altered plasma levels of endocannabinoids and related lipid mediators. Following the one-week recovery we identified significantly reduced BALF cellularity and cytokine/chemokine release along with increased BALF amphiregulin and resolvins in DHA diet-fed versus control diet-fed mice challenged with HDE. We further report observations on the effects of repetitive HDE exposure on lung Ym1+ and Arg-1+ macrophages. Overall, our findings support a protective role for DHA and identify DHA-derived resolvins and endocannabinoids among the potential mediators of DHA in altering airway inflammation in chronic agricultural dust exposure.

A rat model to investigate quality of recovery after abdominal surgery

Introduction

Major advances in therapies to optimize recovery after surgery have been limited by the lack of an animal model that can mimic major domains of postoperative sickness behavior in humans. We hypothesized that the integration of commonly impaired domains of quality of recovery in humans could be reproduced in a rat model.

Objectives

To create a rat model that can mimic surgical recovery in humans.

Methods

Adult male Sprague-Dawley rats were used in the development of a quality of recovery score after surgery. Six physiological parameters or behaviors were tested in naive, sham, and laparotomized animals. A quality of recovery score was constructed and ranged from 18 (no impairment) to 0 (gross impairment). We treated animals with a nutraceutical intervention consisting of aspirin and eicosapentaenoic acid. Inflammatory markers and specialized proresolving mediators were measured in serum and the intestinal mucosa of rats, respectively.

Results

We observed a significant reduction in quality of recovery scores on postoperative days 1 (median, interquartile: 6 [4.75-8.25] vs naive rats: 17.5 [15.5-18]), 2 (median, interquartile: 13 [11.25-13.25], P < 0.001 vs naive rats: 17 [17-18], P = 0.001), and 3 (median, interquartile: 14.5 [13.5-16] vs naive rats: 17 [15.75-18], P < 0.02). Surgery promoted a significant increase in the concentrations of inflammatory cytokines, but it reduced levels of interleukin-12p70 and macrophage colony-stimulating factor. Lipoxin B4 and 13-HODE were significantly higher in laparotomized rats. Aspirin + eicosapentaenoic acid substantially improved recovery scores and modulated the postsurgical inflammatory response.

Conclusion

Our novel rat model can be used to study mechanisms governing surgical recovery in rats.

Gene correlation network analysis to identify regulatory factors in sepsis

BACKGROUND AND OBJECTIVES

Sepsis is a leading cause of mortality and morbidity in the intensive care unit. Regulatory mechanisms underlying the disease progression and prognosis are largely unknown. The study aimed to identify master regulators of mortality-related modules, providing potential therapeutic target for further translational experiments.

METHODS

The dataset GSE65682 from the Gene Expression Omnibus (GEO) database was utilized for bioinformatic analysis. Consensus weighted gene co-expression netwoek analysis (WGCNA) was performed to identify modules of sepsis. The module most significantly associated with mortality were further analyzed for the identification of master regulators of transcription factors and miRNA.

RESULTS

A total number of 682 subjects with various causes of sepsis were included for consensus WGCNA analysis, which identified 27 modules. The network was well preserved among different causes of sepsis. Two modules designated as black and light yellow module were found to be associated with mortality outcome. Key regulators of the black and light yellow modules were the transcription factor CEBPB (normalized enrichment score = 5.53) and ETV6 (NES = 6), respectively. The top 5 miRNA regulated the most number of genes were hsa-miR-335-5p (n = 59), hsa-miR-26b-5p (n = 57), hsa-miR-16-5p (n = 44), hsa-miR-17-5p (n = 42), and hsa-miR-124-3p (n = 38). Clustering analysis in 2-dimension space derived from manifold learning identified two subclasses of sepsis, which showed significant association with survival in Cox proportional hazard model (p = 0.018).

CONCLUSIONS

The present study showed that the black and light-yellow modules were significantly associated with mortality outcome. Master regulators of the module included transcription factor CEBPB and ETV6. miRNA-target interactions identified significantly enriched miRNA.

PCTR1 ameliorates lipopolysaccharide-induced acute inflammation and multiple organ damage via regulation of linoleic acid metabolism by promoting FADS1/FASDS2/ELOV2 expression and reducing PLA2 expression

Gram-negative bacterial infection causes an excessive inflammatory response and acute organ damage or dysfunction due to its outer membrane component, lipopolysaccharide (LPS). Protectin conjugates in tissue regeneration 1 (PCTR1), an endogenous lipid mediator, exerts fundamental anti-inflammation and pro-resolution during infection. In the present study, we examined the properties of PCTR1 on the systemic inflammatory response, organic morphological damage and dysfunction, and serum metabolic biomarkers in an LPS-induced acute inflammatory mouse model. The results show that PCTR1 reduced serum inflammatory factors and ameliorated morphological damage and dysfunction of the lung, liver, kidney, and ultimately improved the survival rate of LPS-induced acute inflammation in mice. In addition, metabolomics analysis and high performance liquid chromatography-mass spectrometry revealed that LPS-stimulated serum linoleic acid (LA), arachidonic acid (AA), and prostaglandin E2 (PGE2) levels were significantly altered by PCTR1. Moreover, PCTR1 upregulated LPS-inhibited fatty acid desaturase 1 (FADS1), fatty acid desaturase 2 (FADS2), and elongase of very long chain fatty acids 2 (ELOVL2) expression, and downregulated LPS-stimulated phospholipase A2 (PLA2) expression to increase the intrahepatic content of AA. However, these effects of PCTR1 were partially abrogated by a lipoxin A4 receptor (ALX) antagonist (BOC-2). In summary, via the activation of ALX, PCTR1 promotes the conversion of LA to AA through upregulation of FADS1, FADS2, and ELOVL2 expression, and inhibits the conversion of bound AA into free AA through downregulation of PLA2 expression to decrease the serum AA and PGE2 levels.

Inflammation resolution and specialized pro-resolving lipid mediators in CNS diseases

Introduction: Inflammation resolution induced by specialized pro-resolving lipid mediators (SPMs) is a new concept. The application of SPMs is a promising therapeutic strategy that can potentially supersede anti-inflammatory drugs. Most CNS diseases are associated with hyperreactive inflammatory damage. CNS inflammation causes irreversible neuronal loss and permanent functional impairments. Given the high mortality and morbidity rates, the investigation of therapeutic strategies to ameliorate inflammatory damage is necessary.Areas covered: In this review, we explore inflammation resolution in CNS disorders. We discuss the underlying mechanisms and dynamic changes of SPMs and their precursors in neurological diseases and examine how this can potentially be incorporated into the clinic. References were selected from PubMed; most were published between 2010 and 2019.Expert opinion: Inflammation resolution is a natural process that emerges after acute or chronic inflammation. The evidence that SPMs can effectively ameliorate hyperreactive inflammation, shorten resolution time and accelerate tissue regeneration in CNS disorders. Adjuvants and nanotechnology offer opportunities for SPM drug design; however, more preclinical studies are necessary to investigate basic, critical issues such as safety.

Arachidonic acid and other unsaturated fatty acids and some of their metabolites function as endogenous antimicrobial molecules: A review

Our body is endowed with several endogenous anti-microbial compounds such as interferon, cytokines, free radicals, etc. However, little attention has been paid to the possibility that lipids could function as antimicrobial compounds. In this short review, the antimicrobial actions of various polyunsaturated fatty acids (PUFAs, mainly free acids) and their putative mechanisms of action are described. In general, PUFAs kill microbes by their direct action on microbial cell membranes, enhancing generation of free radicals, augmenting the formation of lipid peroxides that are cytotoxic, and by increasing the formation of their bioactive metabolites, such as prostaglandins, lipoxins, resolvins, protectins and maresins that enhance the phagocytic action of leukocytes and macrophages. Higher intakes of α-linolenic and cis-linoleic acids (ALA and LA respectively) and fish (a rich source of eicosapentaenoic acid and docosahexaenoic acid) might reduce the risk pneumonia. Previously, it was suggested that polyunsaturated fatty acids (PUFAs): linoleic, α-linolenic, γ-linolenic (GLA), dihomo-GLA (DGLA), arachidonic (AA), eicosapentaenoic (EPA), and docosahexaenoic acids (DHA) function as endogenous anti-bacterial, anti-fungal, anti-viral, anti-parasitic, and immunomodulating agents. A variety of bacteria are sensitive to the growth inhibitory actions of LA and ALA in vitro. Hydrolyzed linseed oil can kill methicillin-resistant Staphylococcus aureus. Both LA and AA have the ability to inactivate herpes, influenza, Sendai, and Sindbis virus within minutes of contact. AA, EPA, and DHA induce death of Plasmodium falciparum both in vitro and in vivo. Prostaglandin E1 (PGE1) and prostaglandin A (PGA), derived from DGLA, AA, and EPA inhibit viral replication and show anti-viral activity. Oral mucosa, epidermal cells, lymphocytes and macrophages contain and release significant amounts of PUFAs on stimulation. PUFAs stimulate NADPH-dependent superoxide production by macrophages, neutrophils and lymphocytes to kill the invading microorganisms. Cytokines induce the release of PUFAs from cell membrane lipid pool, a potential mechanism for their antimicrobial action. AA, EPA, and DHA give rise to lipoxins (LXs), resolvins, protectins, and maresins that limit and resolve inflammation and have antimicrobial actions. Thus, PUFAs and their metabolites have broad antimicrobial actions.

Identification of key pathogenic genes of sepsis based on the Gene Expression Omnibus database

Sepsis is a life-threatening condition in which an uncontrolled inflammatory host response is triggered. The exact pathogenesis of sepsis remains unclear. The aim of the present study was to identify key genes that may aid in the diagnosis and treatment of sepsis. mRNA expression data from blood samples taken from patients with sepsis and healthy individuals was downloaded from the Gene Expression Omnibus database and differentially expressed genes (DEGs) between the two groups were identified. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and protein-protein interaction (PPI) network construction, was performed to investigate the function of the identified DEGs. Furthermore, for validation of these results, the expression levels of several DEGs were analyzed by reverse transcription quantitative-polymerase chain reaction (RT-qPCR) in three patients with sepsis and three healthy blood samples to support the results obtained from the bioinformatics analysis. Receiver operating characteristic analyses were also used to analyze the diagnostic ability of the identified DEGs for sepsis. The results demonstrated that a total of 4,402 DEGs, including 1,960 upregulated and 2,442 downregulated genes, were identified between patients with sepsis and healthy individuals. KEGG pathway analysis revealed that 39 DEGs were significantly enriched in toll-like receptor signaling pathways. The top 20 upregulated and downregulated DEGs were used to construct the PPI network. Hub genes with high degrees, including interleukin 1 receptor-associated kinase 3 (IRAK3), S100 calcium-binding protein (S100)A8, angiotensin II receptor-associated protein (AGTRAP) and S100A9, were demonstrated to be associated sepsis. Furthermore, RT-qPCR results demonstrated that IRAK3, adrenomedullin (ADM), arachidonate 5-lipoxygenase (ALOX5), matrix metallopeptidase 9 (MMP9) and S100A8 were significantly upregulated, while ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1) was upregulated but not significantly, in blood samples from patients with sepsis compared with healthy individuals, which was consistent with bioinformatics analysis results. Therefore, AGTRAP, IRAK3, ADM, ALOX5, MMP9, S100A8 and ENTPD1 were identified to have potential diagnostic value in sepsis. In conclusion, dysregulated levels of the AGTRAP, IRAK3, ADM, ALOX5, MMP9, S100A8 and ENTPD1 genes may be involved in sepsis pathophysiology and may be utilized as potential diagnostic biomarkers or therapeutic targets.

Hydroxytyrosol prevents reduction in liver activity of Δ-5 and Δ-6 desaturases, oxidative stress, and depletion in long chain polyunsaturated fatty acid content in different tissues of high-fat diet fed mice

Background

Eicosapentaenoic acid (EPA, C20:5n-3), docosahexaenoic acid (DHA, C22:6n-3) and arachidonic acid (AA, C20:4n-6) are long-chain polyunsaturated fatty acids (LCPUFAs) with relevant roles in the organism. EPA and DHA are synthesized from the precursor alpha-linolenic acid (ALA, C18:3n-3), whereas AA is produced from linoleic acid (LA, C18:2n-6) through the action of Δ5 and Δ6-desaturases. High-fat diet (HFD) decreases the activity of both desaturases and LCPUFA accretion in liver and other tissues. Hydroxytyrosol (HT), a natural antioxidant, has an important cytoprotective effects in different cells and tissues.

Methods

Male mice C57BL/6 J were fed a control diet (CD) (10% fat, 20% protein, 70% carbohydrates) or a HFD (60% fat, 20% protein, 20% carbohydrates) for 12 weeks. Animals were daily supplemented with saline (CD) or 5 mg HT (HFD), and blood and the studied tissues were analyzed after the HT intervention. Parameters studied included liver histology (optical microscopy), activity of hepatic desaturases 5 and 6 (gas-liquid chromatography of methyl esters derivatives) and antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase by spectrophotometry), oxidative stress indicators (glutathione, thiobarbituric acid reactants, and the antioxidant capacity of plasma), gene expression assays for sterol regulatory element-binding protein 1c (SREBP-1c) (qPCR and ELISA), and LCPUFA profiles in liver, erythrocyte, brain, heart, and testicle (gas-liquid chromatography).

Results

HFD led to insulin resistance and liver steatosis associated with SREBP-1c upregulation, with enhancement in plasma and liver oxidative stress status and diminution in the synthesis and storage of n-6 and n-3 LCPUFAs in the studied tissues, compared to animals given control diet. HT supplementation significantly reduced fat accumulation in liver and plasma as well as tissue metabolic alterations induced by HFD. Furthermore, a normalization of desaturase activities, oxidative stress-related parameters, and tissue n-3 LCPUFA content was observed in HT-treated rats over control animals.

Conclusions

HT supplementation prevents metabolic alterations in desaturase activities, oxidative stress status, and n-3 LCPUFA content in the liver and extrahepatic tissues of mice fed HFD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-017-0450-5) contains supplementary material, which is available to authorized users.