Immune communication between the intestinal microbiota and the cardiovascular system

Macrophages in vascular disease: Roles of mitochondria and metabolic mechanisms

Macrophages are a dynamic cell type of the immune system implicated in the pathophysiology of vascular diseases and are a major contributor to pathological inflammation. Excessive macrophage accumulation, activation, and polarization is observed in aortic aneurysm (AA), atherosclerosis, and pulmonary arterial hypertension. In general, macrophages become activated and polarized to a pro-inflammatory phenotype, which dramatically changes cell behavior to become pro-inflammatory and infiltrative. These cell types become cumbersome and fail to be cleared by normal mechanisms such as autophagy. The result is a hyper-inflammatory environment causing the recruitment of adjacent cells and circulating immune cells to further augment the inflammatory response. In AA, this leads to excessive ECM degradation and chemokine secretion, ultimately causing macrophages to dominate the immune cell landscape in the aortic wall. In atherosclerosis, monocytes are recruited to the vascular wall, where they polarize to the pro-inflammatory phenotype and induce inflammatory pathway activation. This leads to the development of foam cells, which significantly contribute to neointima and necrotic core formation in atherosclerotic plaques. Pro-inflammatory macrophages, which affect other vascular diseases, present with fragmented mitochondria and corresponding metabolic dysfunction. Targeting macrophage mitochondrial dynamics has proved to be an exciting potential therapeutic approach to combat vascular disease. This review will summarize mitochondrial and metabolic mechanisms of macrophage activation, polarization, and accumulation in vascular diseases.

Hexane extract from black soldier fly prepupae: A novel immunomodulatory strategy against Aeromonas hydrophila infection in zebrafish

Background and Aim

Aeromonas hydrophila infections in fish result in significant financial losses within aquaculture. Previous research indicates black soldier fly (BSF) prepupae provide immunomodulatory benefits through their fatty acids, chitin, and proteins. The study evaluated the impact of hexane extract from black soldier fly prepupae (HEBP) on interleukin (IL)-4 and IL-10 cytokine expression in zebrafish, both infected and uninfected with A. hydrophila.

Materials and Methods

Adult zebrafish (aged 4-5 months) was assigned to a negative control group (fed commercial feed), a positive control group (commercial feed + A. hydrophila infection at 107 colony-forming unit/mL), and three treatment groups (T1, T2, T3) that received HEBP at doses of 1000; 2000 and 4000 mg/kg feed for 30 days, respectively. A. hydrophila infection was introduced on day 31 through immersion. Analysis of IL-4 and IL-10 expression in the head kidney trunk region (body without head and tail) through quantitative polymerase chain reaction was conducted on day 33.

Results

The HEBP modulated the immune response to A. hydrophila infection at a concentration of 1000 mg/kg feed, as evidenced by an increase in IL-4 and IL-10 expression in the groups not infected with the bacteria. However, these cytokines were decreased in the infected groups.

Conclusion

A feed concentration of 1000 mg/kg HEBP was identified as optimal for cytokine modulation. This discovery marks a significant advancement in the development and benefit of a natural extract-based immunomodulator in a zebrafish model, which is potentially immunotherapeutic against bacterial infections in fish for the aquaculture industry.

Akkermansia muciniphila extracellular vesicles have a protective effect against hypertension

Akkermansia muciniphila (Am) shows a beneficial role as a probiotic in the treatment of metabolic syndrome. However, the mechanism remains to be elucidated. We tested the hypothesis that Am extracellular vesicles (AmEVs) have a protective effect against hypertension. Extracellular vesicles purified from anaerobically cultured Am were characterized by nanoparticle tracking analysis, transmission electron microscopy, and silver stain after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). AmEVs (1.0 × 1010 log particles/L) or vehicles were added into organ baths to induce vasorelaxation. In addition, AmEVs (1.0 × 108 or 1.0 × 109 particles/kg) or vehicles were injected into the tail veins of Wistar-Kyoto rats (WKYs) and spontaneously hypertensive rats (SHRs) weekly for 4 weeks. Peripheral blood mononuclear cells (PBMCs) and splenocytes isolated from both rat strains were analyzed by flow cytometry, RT-qPCR, and western blot. AmEVs affected neither vascular contraction nor endothelial relaxation in thoracic aortas. Moreover, AmEVs protected against the development of hypertension in SHRs without a serious adverse reaction. Additionally, AmEVs increased the population of T regulatory (Treg) cells and tended to reduce proinflammatory cytokines. These results indicate that AmEVs have a protective effect against hypertension without a serious adverse reaction. Therefore, it is foreseen that AmEVs may be utilized as a novel therapeutic for the treatment of hypertension.

The Mediterranean Diet, Its Microbiome Connections, and Cardiovascular Health: A Narrative Review

The Mediterranean diet (MD), rich in minimally processed plant foods and in monounsaturated fats but low in saturated fats, meat, and dairy products, represents one of the most studied diets for cardiovascular health. It has been shown, from both observational and randomized controlled trials, that MD reduces body weight, improves cardiovascular disease surrogates such as waist-to-hip ratios, lipids, and inflammation markers, and even prevents the development of fatal and nonfatal cardiovascular disease, diabetes, obesity, and other diseases. However, it is unclear whether it offers cardiovascular benefits from its individual components or as a whole. Furthermore, limitations in the methodology of studies and meta-analyses have raised some concerns over its potential cardiovascular benefits. MD is also associated with characteristic changes in the intestinal microbiota, mediated through its constituents. These include increased growth of species producing short-chain fatty acids, such as Clostridium leptum and Eubacterium rectale, increased growth of Bifidobacteria, Bacteroides, and Faecalibacterium prausnitzii species, and reduced growth of Firmicutes and Blautia species. Such changes are known to be favorably associated with inflammation, oxidative status, and overall metabolic health. This review will focus on the effects of MD on cardiovascular health through its action on gut microbiota.

Targeted arginine metabolomics combined with metagenomics revealed the potential mechanism of Pueraria lobata extract in treating myocardial infarction

The extraction methods for traditional Chinese medicine (TCM) may have varying therapeutic effects on diseases. Currently, Pueraria lobata (PL) is mostly extracted with ethanol, but decoction, as a TCM extraction method, is not widely adopted. In this study, we present a strategy that integrates targeted metabolomics, 16 s rDNA sequencing technology and metagenomics for exploring the potential mechanism of the water extract of PL (PLE) in treating myocardial infarction (MI). Using advanced analytical techniques like ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), we comprehensively characterized PLE's chemical composition. Further, we tested its efficacy in a rat model of MI induced by ligation of the left anterior descending branch of the coronary artery (LAD). We assessed cardiac enzyme levels and conducted echocardiograms. UPLC-MS/MS was used to compare amino acid differences in serum. Furthermore, we investigated fecal samples using 16S rDNA sequencing and metagenomic sequencing to study intestinal flora diversity and function. This study demonstrated PLE's effectiveness in reducing cardiac injury in LAD-ligated rats. Amino acid metabolomics revealed significant improvements in serum levels of arginine, citrulline, proline, ornithine, creatine, creatinine, and sarcosine in MI rats, which are key compounds in the arginine metabolism pathway. Enzyme-linked immunosorbent assay (ELISA) results showed that PLE significantly improved arginase (Arg), nitric oxide synthase (NOS), and creatine kinase (CK) contents in the liver tissue of MI rats. 16 s rDNA and metagenome sequencing revealed that PLE significantly improved intestinal flora imbalance in MI rats, particularly in taxa such as Tuzzerella, Desulfovibrio, Fournierella, Oscillibater, Harryflintia, and Holdemania. PLE also improved the arginine metabolic pathway in the intestinal microorganisms of MI rats. The findings indicate that PLE effectively modulates MI-induced arginine levels and restores intestinal flora balance. This study, the first to explore the mechanism of action of PLE in MI treatment considering amino acid metabolism and intestinal flora, expands our understanding of the potential of PL in MI treatment. It offers fresh insights into the mechanisms of PL, guiding further research and development of PL-based medicines.

Acupuncture modulates the gut microbiota in Alzheimer's disease: current evidence, challenges, and future opportunities

Alzheimer's disease, one of the most severe and common neurodegenerative diseases, has no effective cure. Therefore it is crucial to explore novel and effective therapeutic targets. The gut microbiota - brain axis has been found to play a role in Alzheimer's disease by regulating the neuro-immune and endocrine systems. At the same time, acupuncture can modulate the gut microbiota and may impact the course of Alzheimer's disease. In this Review, we discuss recent studies on the role of acupuncture on the gut microbiota as well current challenges and future opportunities of acupuncture as potential treatment for the prevention and treatment of Alzheimer's disease.

Integrated characterizations of intestinal bacteria and transcriptomics revealed the acute stress response to carbonate alkalinity in white shrimp Penaeusvannamei

The impact of carbonate alkalinity in saline-alkaline water on aquatic organisms, particularly Penaeus vannamei, a significant species in aquaculture, remains a critical area of study. To elucidate the acute response mechanisms of P. vannamei to elevated carbonate alkalinity environments, we utilized 16S rRNA gene and transcriptome sequencing technologies to analyze intestinal bacteria and gene expressions within various tissues. Our investigation revealed notable changes in specific intestinal bacterial OTUs, whose abundances varied preceding the overall bacterial community, indicating the sensitivity to carbonate alkalinity exposure. These shifts are accompanied by a simplification in bacterial networks and alterations in pathogenic OTUs, notably Aeromonas OTU. Concurrently, gene expression variations were observed across the hepatopancreas, gills, muscles, and intestines, with decreasing numbers of DEGs in the mentioned order. Annotation of these DEGs revealed enrichments in pathways related to transport, catabolism, immune responses, circulatory functions, and lipid metabolism. Notably, correlations between specific intestinal bacterial OTUs and gene expression shifts were identified across these tissues. Several OTUs, attributed to Rhizobiales, Saccharimonadales, Acidovora, and Aeromona, exhibited a correlation with DEGs in all four tissues, primarily associated with amino acid metabolism, signal transduction, and transport and catabolism pathways. Our study provides comprehensive insights into the dynamic responses of P. vannamei to elevated carbonate alkalinity stress. These findings contribute crucial knowledge for effective P. vannamei cultivation in saline-alkaline water, advancing our understanding in this field.