Olfactory receptor responding to gut microbiota-derived signals plays a role in renin secretion and blood pressure regulation

Olfactory receptors in neural regeneration in the central nervous system

Olfactory receptors are crucial for detecting odors and play a vital role in our sense of smell, influencing behaviors from food choices to emotional memories. These receptors also contribute to our perception of flavor and have potential applications in medical diagnostics and environmental monitoring. The ability of the olfactory system to regenerate its sensory neurons provides a unique model to study neural regeneration, a phenomenon largely absent in the central nervous system. Insights gained from how olfactory neurons continuously replace themselves and reestablish functional connections can provide strategies to promote similar regenerative processes in the central nervous system, where damage often results in permanent deficits. Understanding the molecular and cellular mechanisms underpinning olfactory neuron regeneration could pave the way for developing therapeutic approaches to treat spinal cord injuries and neurodegenerative diseases like Alzheimer's disease. Olfactory receptors are found in almost any cell of every organ/tissue of the mammalian body. This ectopic expression provides insights into the chemical structures that can activate olfactory receptors. In addition to odors, olfactory receptors in ectopic expression may respond to endogenous compounds and molecules produced by mucosal colonizing microbiota. The analysis of the function of olfactory receptors in ectopic expression provides valuable information on the signaling pathway engaged upon receptor activation and the receptor's role in proliferation and cell differentiation mechanisms. This review explores the ectopic expression of olfactory receptors and the role they may play in neural regeneration within the central nervous system, with particular attention to compounds that can activate these receptors to initiate regenerative processes. Evidence suggests that olfactory receptors could serve as potential therapeutic targets for enhancing neural repair and recovery following central nervous system injuries.

The mitochondria-gut microbiota crosstalk - A novel frontier in cardiovascular diseases

Cardiovascular diseases (CVDs), including hypertension, atherosclerosis, and cardiomyopathy among others, remain the leading cause of global morbidity and mortality. Despite advances in treatment, the complex pathophysiology of CVDs necessitates innovative approaches to improve patient outcomes. Recent research has uncovered a dynamic interplay between mitochondria and gut microbiota, fundamentally altering our understanding of cardiovascular health. However, while existing studies have primarily focused on individual components of this axis, this review examines the bidirectional communication between these biological systems and their collective impact on cardiovascular health. Mitochondria, serving as cellular powerhouses, are crucial for maintaining cardiovascular homeostasis through oxidative phosphorylation (OXPHOS), calcium regulation, and redox balance. Simultaneously, the gut microbiota influences cardiovascular function through metabolite production, barrier integrity maintenance, and immune system modulation. The mitochondria-gut microbiota axis operates through various molecular mechanisms, including microbial metabolites such as trimethylamine N-oxide (TMAO), short-chain fatty acids (SCFA), and secondary bile acids, which directly influence mitochondrial function. Conversely, mitochondrial stress signals and damage-associated molecular patterns (DAMPs) affect gut microbial communities and barrier function. Key signalling pathways, including AMP-activated protein kinase (AMPK), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and the silent information regulator 1-peroxisome proliferator-activated receptor gamma coactivator 1-alpha (SIRT1-PGC-1α) axis, integrate these interactions, highlighting their role in CVD pathogenesis. Understanding these interactions has revealed promising therapeutic targets, suggesting new therapies aimed at both mitochondrial function and gut microbiota composition. Thus, this review provides a comprehensive framework for leveraging the mitochondria-gut microbiota axis in providing newer therapeutics for CVDs by targeting the AMPK/SIRT-1/PGC-1α/NF-κB signalling.

A highly active angiotensin I-converting enzyme inhibitory peptide KAKW designed based on the role of C-terminal residue, and its antihypertensive effects on spontaneously hypertensive rats

Angiotensin converting enzyme (ACE) inhibitory peptide KAKP with IC50 of 7.23 ± 0.30 μM was identified from trypsin hydrolysate of pistachio (Pistacia vera L.) through multiple purifications. A series of peptides were designed based on KAKP to reveal the role of the C-terminal residue in the ACE inhibition, including KAK-Xaa (hydrophobic residue), KAK and KAPK. The designed peptide KAKW exhibited a superior ACE inhibitory effect with IC50 of 2.02 ± 0.20 μM. Molecular docking discovered that the hydrophobic C-terminal residues with ring structure facilitated the interaction with Zn2+ and π-π interactions within the ACE active pocket. Isothermal titration calorimetry revealed that the thermodynamic property of KAKW was enthalpy-driven with a lower Kd (57.7 nM) than KAKP (141 nM). KAKW could decrease 20 mmHg SBP at 4 h and 18 mmHg DBP at 6 h during the acute trial of spontaneously hypertensive rats (SHRs), compared to that Lisinopril dropped 33 mmHg SBP and 28 mmHg DBP at 2 h. After a subacute administration of KAKW for 4 w, the strong inhibition of 61.6 % serum ACE activity and the reduction of 33.3 % angiotensin Ⅱ level were achieved. Although KAKW was less potent than Lisinopril, it provided a more moderate and sustained reduction in blood pressure, beneficial for long-term hypertension management. Meanwhile, KAKW ameliorated gut microbiota dysbiosis in SHRs and increased the levels of fecal short-chain fatty acids, demonstrating advantages over Lisinopril in modulating gut microbiota. This work provides a novel scheme for structure-activity study and a prospective candidate for hypertension management.

Impact of gender and reproductive states on diets and intestinal microbiota in Pratt's leaf-nosed bats (Hipposideros pratti)

Lactation represents a critical evolutionary adaptation in mammals, imposing heightened nutritional demands that drive shifts in foraging behavior and intestinal microbiota to optimize nutrient acquisition. In the sexually dimorphic Pratt's leaf-nosed bat (Hipposideros pratti), males exhibit enlarged transverse lobes posterior to the nasal leaf, a morphological trait may influence echolocation dynamics and dietary niche partitioning. This provides an opportunity to examine dietary and microbiota differences between genders and across various reproductive states. Using high-throughput sequencing of fecal samples from male (HPM), non-lactating female (HPF), and lactating female (HPFL) H. pratti collected in late June, we identified gender- and physiology-linked ecological strategies. While dietary diversity indices showed no significant intergroup differences, compositional analysis revealed distinct prey preferences: both HPM and HPFL predominantly consumed Coleoptera, whereas HPF favored Diptera. Coleoptera's larger size and nutrient profile-rich in leucine, isoleucine, and chitin-likely optimize energy efficiency for HPFL, reducing foraging effort while supplying amino acids critical for mammary gland function and immunity. Gender-based differences were observed in intestinal microbiota diversity, with females demonstrating higher diversity indices compared to males. Males showed a notable abundance of Clostridium sensu stricto 1, a proteolytic genus associated with Coleoptera digestion but linked to inflammatory risks via pathogenic strains. The HPFL group exhibited microbiota enriched in Lactococcus (chitinolytic taxa) and lactation-adapted symbionts: Lachnoclostridium may suppress pro-inflammatory responses via acetate production, while Pseudonocardia may enhance calcium homeostasis and antimicrobial defense. This study advances understanding of host-microbe coadaptation in mitigating life-history trade-offs and highlights ecological drivers of microbiota plasticity in insectivorous bats.

The gut microbiota and aging: interactions, implications, and interventions

The human microbiota, a complex ecosystem of microorganisms inhabiting various body sites, particularly the gut, plays a crucial role in maintaining health and influencing disease susceptibility. Dysbiosis, characterized by alterations in microbial composition and diversity, has been implicated in numerous diseases, including those associated with aging. This review examines the complex relationship between gut microbiota and aging, highlighting the age-associated gut microbiota alterations, the factors contributing to these changes, the links between microbiota and age-related diseases, and the potential of interventions targeting the microbiome to extend lifespan and improve health outcomes in the elderly. Further research is needed to unravel the intricate mechanisms underlying the interplay between the microbiome and aging, paving the way for innovative strategies to promote healthy aging.

Microbiota-derived acetate suppresses sympathetic outflow via olfactory receptor 59 in the rostral ventrolateral medulla

BACKGROUND

Dysbiosis of gut microbiota is closely associated with the development of hypertension, yet the underlying mechanism remains unclear. In this study, we aimed to elucidate the molecular mechanisms through which microbiota-derived acetate regulates sympathetic activity and arterial blood pressure (ABP). Bulk RNA sequencing was used to determine the expression of short-chain fatty acids receptors in the rostral ventrolateral medulla (RVLM). We examined the influence of olfactory receptor 59 (Olr59) on renal sympathetic nerve activity (RSNA) and ABP in anesthetized rats. The effect of Olr59 on the excitability of RVLM neurons was assessed through calcium imaging. Moreover, the 24-hour ambulatory blood pressure of conscious rats was recorded using radiotelemetry. The RNA sequencing results indicated that Olr59 was the most highly expressed short-chain fatty acids receptor in the rat RVLM and was upregulated in spontaneously hypertensive rats (SHR). Injection of the Olr59 agonist acetate or β-ionone into the RVLM reduced ABP and RSNA. However, administration of Olr59 antagonist or the knockdown of Olr59 in RVLM neurons did not significantly alter ABP, but it counteracted the hypotensive effect of acetate within the RVLM. Application of acetate or β-ionone to isolated brain slices mainly inhibited calcium signal in spinally-projecting RVLM neurons. Furthermore, overexpression of Olr59 in RVLM neurons via adeno-associated virus reduced ABP in SHR. Microbiota-derived acetate inhibits sympathetic activity and decreases blood pressure via Olr59 in the RVLM. Thus, Olr59 represents a promising new target for the treatment of hypertension.

Promising odor-based therapeutics targeting ectopic olfactory receptor proteins in cancer: A review

Cancer remains a formidable adversary in global health, necessitating the development of innovative strategies to curb the proliferation, invasion, and metastasis of cancer cells for effective treatment outcomes. Traditional cancer therapies often fall short in addressing the diverse therapeutic requirements of patients. Consequently, the exploration of novel therapeutic targets has become increasingly vital. Olfactory receptors (ORs) belonging to the G protein-coupled receptor (GPCR) subfamily, are present in non-nasal tissues and contribute to a wide range of physiological functions. ORs are specifically expressed in malignant tumors and have emerged as potential biomarkers for cancer detection. They can regulate diverse tumor biological behaviors and are involved in the development of malignant tumors, indicating that they might serve as potential targets for cancer treatment. This paper provides a comprehensive review of the ectopic expression of ORs, their functions in malignancies and odor-based therapeutics targeting ectopic olfactory receptors (EORs) in cancer, and aims to clarify their connection with cancer, providing new clues for probing the tumor biology and developing therapeutic strategies against cancer.

The Causality between Gut Microbiota and Hypertension and Hypertension-related Complications: A Bidirectional Two-Sample Mendelian Randomization Analysis

BACKGROUND

Recent studies have highlighted a connection between gut microbiota and hypertension, yet the precise nature of this relationship remains unclear.

OBJECTIVE

This research aims to analyze the causal link between gut microbiota and hypertension, along with associated complications, utilizing two-sample bidirectional Mendelian randomization (MR).

MATERIALS AND METHODS

Summary data from genome-wide association studies (GWAS) meta-analyses, including gut microbiota GWAS data from 24 cohorts, and the latest GWAS data for hypertension-related conditions were acquired. Employing various MR methods, including Inverse-variance weighted (IVW), MR-Egger, Weighted Median, Simple Mode, and Weighted Mode, we investigated the association between gut microbiota and hypertension-related conditions. Sensitivity analyses were conducted for result stability, and reverse MR analysis assessed the potential for reverse causality.

RESULTS

The Mendelian randomization analysis involving 199 microbial taxa and four phenotypes identified 46 microbial taxa with potential causal links to hypertension and its complications. Following Bonferroni correction, genus.Victivallis showed a robust causal relationship with hypertension (OR = 1.08, 95% CI = 1.04-1.12, P = 9.82e-5). This suggests an 8% increased risk of hypertension with each unit rise in genus.Victivallis abundance.

CONCLUSION

In conclusion, this study establishes a causal connection between gut microbiota and hypertension, along with common associated complications. The findings unveil potential targets and evidence for future hypertension and complication treatment through gut microbiota interventions, offering a novel avenue for therapeutic exploration.

"Gut Microbiota as a Therapeutic Target for Hypertension: Challenges and Insights for Future Clinical Applications" "Gut Microbiota and Hypertension Therapy"

PURPOSE OF REVIEW

Systemic hypertension is a major risk factor for cardiovascular disease and remains challenging to manage despite the widespread use of antihypertensive medications and lifestyle modifications. This review explores the role of gut microbiota in hypertension development and regulation, highlighting key mechanisms such as inflammation, gut-brain axis modulation, and bioactive metabolite production. We also assess the potential of microbiota-targeted therapies for hypertension management.

RECENT FINDINGS

Emerging evidence indicates that microbial dysbiosis, high-salt diets, and gut-derived metabolites such as short-chain fatty acids (SCFAs) and bile acids significantly influence blood pressure regulation. Preclinical and early clinical studies suggest that interventions targeting gut microbiota, including probiotics, prebiotics, synbiotics, fecal microbiota transplantation (FMT), and dietary modifications, may help modulate hypertension. However, variability in gut microbiota composition among individuals and limited human trial data pose challenges to translating these findings into clinical practice. While microbiota-based therapies show promise for hypertension management, further research is needed to establish their efficacy and long-term effects. Large-scale, standardized clinical trials are crucial for understanding the therapeutic potential and limitations of gut microbiota interventions. A deeper understanding of the gut-hypertension axis could lead to novel, personalized treatment strategies for hypertension.

Microbiome-based dietary supplements for better development and healthy brain

Microbiome-based dietary supplements have gained attention for their role in enhancing brain development and cognitive health. The gut microbiome influences neurological functions through the gut-brain axis, impacting neurotransmitter production, immune regulation, and metabolic pathways. Dysbiosis is linked to neurological disorders such as Alzheimer's, Parkinson's, and autism spectrum disorders. This chapter explores dietary interventions targeting the microbiome, emphasising probiotics, prebiotics, and postbiotics. Additionally, AI and machine learning are transforming microbiome research by enabling personalised supplementation strategies tailored to individual gut profiles. Ethical challenges, including data privacy and algorithmic bias, are also discussed. Advances in big data analytics and predictive modelling are paving the way for precision-targeted interventions to optimise brain health. While microbiome-based therapies hold great promise, further clinical validation and regulatory frameworks are needed to ensure their efficacy and accessibility. This chapter highlights the future potential of microbiome-targeted strategies in neuroprotection and cognitive well-being.

Conversion Reaction of Stable-Isotope Oxygen Labeling of Carboxylic Acids for Accurate Screening LC-MS/MS Assay: Application of Behavioral Changes of Short-Chain Fatty Acids in Sports Athletes under Exercise Loading

Short-chain fatty acids (SCFAs) have attracted considerable interest as potential biomarkers, therapeutic targets, and nutritional factors in athletic training. SCFAs are typically produced by the intestinal microbiome and exhibit various structural forms, including linear- and branched-chain types. In particular, branched-chain SCFAs have been associated with muscle metabolism during exercise loading. Consequently, accurate and efficient analytical methods are essential for identifying these biomarkers. Liquid chromatography-tandem mass spectrometry is a suitable and accurate technique for SCFA analysis; however, stable isotope calibrations are required for all analytes. Because of technological limitations, the available species are restricted to certain types of SCFAs. To address this issue, this study performed a simple conversion reaction involving the incorporation of 18O into the carboxyl group. Specifically, oxygen atoms in the carboxyl groups were substituted with 18O sourced from commercially available H218O. An SCFA mixture standard solution was successfully labeled under optimized conditions, and the SIL purity and amount were sufficient for isotope dilution (95.2-96.9%, 250 assays using 10 μL of H218O). Moreover, no reversion to 16O was observed during storage or analysis. Analytical validation was performed in human serum using the substituted isotopic standard mixture, achieving good accuracy (90-110%) and precision (<10% relative standard deviation) across three concentration levels. Finally, changes in SCFA patterns were examined in athletes during exercise loading.

Assessment of the association between constipation and atherosclerosis in cardiovascular and cerebrovascular diseases: a systematic review and meta-analysis

INTRODUCTION

Cardiovascular and cerebrovascular diseases remain leading causes of morbidity and mortality worldwide, with atherosclerosis as a key underlying mechanism.

METHODS

A systematic review was conducted of studies published between 2000 and August 2024, sourced from PubMed, Web of Science, Cochrane, and EMBASE databases. Twelve studies, involving 5,772,682 adults across six countries, met predefined inclusion criteria. Study quality was assessed using the Newcastle-Ottawa Scale (NOS) and the Agency for Healthcare Research and Quality (AHRQ) scale. A meta-analysis was performed to quantify the association.

RESULTS

The meta-analysis revealed a statistically significant association between constipation and atherosclerosis-related cardiovascular and cerebrovascular diseases, with a pooled odds ratio of 1.18 (95 % CI: 1.08-1.30). This finding indicates that individuals with constipation may face an elevated risk of these conditions.

CONCLUSIONS

These findings suggest that constipation could serve as a potential risk factor or marker warranting further investigation in clinical and mechanistic studies.

Renal Ghrelin-Family GPR39 Receptor and Urinary Concentrating Ability

Key Points

Background

Low-calorie intake is associated with substantial changes in volume distribution and volume status in the body, resulting in reduced circulatory volume and a reduction in BP. Activation of the orphan receptor GPR39 dampens food intake and causes weight loss in a glucagon like peptide-1–dependent fashion. We speculated that appetite-regulating signaling might also be responsible for the circulatory volume contraction observed in response to anorectic states.

Methods

To assess the effect of GPR39 fluid homeostasis, we combined in vivo, ex vivo, and in vitro studies to assess the effect of a selective GPR39 agonist (Cpd1324).

Results

Oral gavage of Cpd1324 dose-dependently increased the water intake of wild-type (WT) C57BL/6J mice only and was completely absent in global GPR39 knockout mice. GPR39 is expressed in the distal convoluted tubule and collecting duct of the kidney, and WT mice exclusively showed Cpd1324-induced increase in urine production, increased K+ excretion, and reduced urine concentrating capacity both at baseline and after an 8-hour water restriction compared with vehicle controls. Correspondingly, Cpd1324 reduced AVP-induced cAMP production and directly counteracted the AVP-induced water permeability in perfused cortical collecting ducts. Moreover, specific GPR39 activation reduced the baseline and AVP-stimulated abundance of phosphorylated pS256-aquaporin 2 and pT58-Na+-Cl− cotransporter and diminished the AVP-stimulated pS269-aquaporin 2 abundance in renal tubular suspensions. These effects were seen exclusively in GPR39 WT mice and not in knockout mice.

Conclusions

These data suggest that Cpd1324 directly targets renal GPR39 to induce increased diuresis and consequently stimulate drinking behavior. We conclude that the activation of GPR39 causes diuresis by opposing AVP-induced Na+ and Cl− reabsorption in the distal convoluted tubule and water reabsorption in the collecting duct.

Restorative Effects of Short-Chain Fatty Acids on Corneal Homeostasis Disrupted by Antibiotic-Induced Gut Dysbiosis

The gut microbiota plays a crucial regulatory role in various physiological processes, yet its impact on corneal homeostasis remains insufficiently understood. Here, the effects of antibiotic-induced gut dysbiosis (AIGD) and germ-free conditions were investigated on circadian gene expression, barrier integrity, nerve density, and immune cell activity in the corneas of mice. Both AIGD and germ-free conditions significantly disrupted the overall transcriptomic profile and circadian transcriptomic oscillations in the cornea, as indicated by RNA sequencing. These molecular disturbances were accompanied by a reduction in corneal epithelial thickness, nerve density, corneal sensitivity, and compromised barrier function. Notably, supplementation with short-chain fatty acids (SCFAs) significantly restored corneal integrity in AIGD mice. Further single-cell sequencing revealed that SCFA receptors G-protein-coupled receptor 109A (Hcar2), olfactory receptor 78 (Olfr78), and G-protein-coupled receptor 43 (Ffar2) are expressed in corneal epithelial basal cells, embryonically derived macrophages, perivascular cells, and γδ T cells, respectively. In conclusion, this study demonstrated that the gut microbiota plays a critical role in corneal physiology by regulating circadian gene expression and maintaining barrier function. These findings enhance our understanding of the gut-eye axis, highlighting the cornea as a target for microbiota-derived metabolic signals and underlining the potential therapeutic value of SCFAs in treating corneal dysfunction.

Roles of sensory receptors in non-sensory organs: the kidney and beyond

Olfactory receptors (ORs), taste receptors and opsins are well-known for their pivotal roles in mediating the senses of smell, taste and sight, respectively. However, in the past two decades, research has shown that these sensory receptors also regulate physiological processes in a variety of non-sensory tissues. Although ORs, taste receptors and opsins have all been shown to have physiological roles beyond their traditional locations, most work in the kidney has focused on ORs. To date, renal ORs have been shown to have roles in blood pressure regulation (OLFR78 and OLFR558) and glucose homeostasis (OLFR1393). However, sensory receptors remain drastically understudied outside of traditional sensory systems, in part because of inherent challenges in studying these receptors. Increased knowledge of the physiological and pathophysiological roles of sensory receptors has the potential to substantially improve understanding of the function of numerous organs and systems, including the kidney. In addition, most sensory receptors are G protein-coupled receptors, which are considered to be the most druggable class of proteins, and thus could potentially be exploited as future therapeutic targets.

Changes in kidney functions following acute infusion of low molecular weight polyvinylpyrrolidone in male rats

Polyvinylpyrrolidone (PVP), a water-soluble homopolymer, has been widely used in food, beverage, medical, and experimental tissue preparations. However, the effect of PVP on renal functions remains unknown. We investigated the acute administration of low MW of PVP on renal functions and whether it produces a toxic effect on the kidney. Renal clearance experiments were performed in rats and showed PVP infusion elicited significant diuretic and natriuretic effects. Urine volume, absolute (ENa), and fractional (FENa) Na+ excretion were significantly increased. A relatively small kaliuretic effect was also observed. After 2 h of PVP infusion, blood urea nitrogen (BUN) and urinary concentrations of beta-N-glucosaminidase (NAG) did not change significantly. Alpha-1-microglobulin, an indicator of proximal tubule absorption ability, excretion increased 12-fold, indicating that a large portion of the fluid and Na+ loss is due to reduced absorption in the proximal tubule. The 24-fold increase in ENa and the 12-fold increase in α1-microglobulin excretion suggest that fluid and electrolyte absorption were also reduced in other nephron segments. We conclude that acute low molecular weight PVP infusion produces diuretic and natriuretic effects due to the osmotically induced reduction of proximal tubular absorption, and acute PVP infusion does not cause renal damage.

Molecules-mediated bidirectional interactions between microbes and human cells

Complex molecules-mediated interactions, which are based on the bidirectional information exchange between microbes and human cells, enable the defense against diseases and health maintenance. Recently, diverse single-direction interactions based on active metabolites, immunity factors, and quorum sensing signals have largely been summarized separately. In this review, according to a simplified timeline, we proposed the framework of Molecules-mediated Bidirectional Interactions (MBI) between microbe and humans to decipher and understand their intricate interactions systematically. About the microbe-derived interactions, we summarized various molecules, such as short-chain fatty acids, bile acids, tryptophan catabolites, and quorum sensing molecules, and their corresponding human receptors. Concerning the human-derived interactions, we reviewed the effect of human molecules, including hormones, cytokines, and other circulatory metabolites on microbial characteristics and phenotypes. Finally, we discussed the challenges and trends for developing and deciphering molecule-mediated bidirectional interactions and their potential applications in the guard of human health.

Olfactory Receptors and Tumorigenesis: Implications for Diagnosis and Targeted Therapy

Olfactory receptors (ORs) are a class of G protein-coupled receptors (GPCR) widely distributed in olfactory sensory neurons and various non-olfactory tissues, serving significant physiological and pathological functions in the human body. Increasing evidence reveals the heightened expression of olfactory receptors in tumorous tissues and cells alongside normal tissues. Olfactory receptors have demonstrated influence over tumor cell proliferation and metastasis, establishing a close relationship with tumor initiation and progression. This review highlights the specific molecular actions and signaling pathways of olfactory receptors in the development of human tumors. The potential for precise tumor diagnosis and targeted therapy through therapeutic targeting of olfactory receptors as an adjunct anticancer treatment strategy is being considered.

Exploring the Potential of Stem Cells in Modulating Gut Microbiota and Managing Hypertension

Hypertension, commonly known as high blood pressure, is a significant health issue that increases the risk of cardiovascular diseases, stroke, and renal failure. This condition broadly encompasses both primary and secondary forms. Despite extensive research, the underlying mechanisms of systemic arterial hypertension-particularly primary hypertension, which has no identifiable cause and is affected by genetic and lifestyle agents-remain complex and not fully understood. Recent studies indicate that an imbalance in gut microbiota, referred to as dysbiosis, may promote hypertension, affecting blood pressure regulation through metabolites such as short-chain fatty acids and trimethylamine N-oxide. Current antihypertensive medications face limitations, including resistance and adherence issues, highlighting the need for novel therapeutic approaches. Stem cell therapy, an emerging field in regenerative medicine, shows promise in addressing these challenges. Stem cells, with mesenchymal stem cells being a prime example, have regenerative, anti-inflammatory, and immunomodulatory properties. Emerging research indicates that stem cells can modulate gut microbiota, reduce inflammation, and improve vascular health, potentially aiding in blood pressure management. Research has shown the positive impact of stem cells on gut microbiota in various disorders, suggesting their potential therapeutic role in treating hypertension. This review synthesizes the recent studies on the complex interactions between gut microbiota, stem cells, and systemic arterial hypertension. By offering a thorough analysis of the current literature, it highlights key insights, uncovers critical gaps, and identifies emerging trends that will inform and guide future investigations in this rapidly advancing field.

The microbiome and acute organ injury: focus on kidneys

The microbiome of critically ill patients is significantly altered by both effects of the illnesses and clinical interventions provided during intensive care. Studies have shown that manipulating the microbiome can prevent or modulate complications of critical illness in experimental models and preliminary clinical trials. This review aims to discuss general concepts about the microbiome, including mechanisms of modifying acute organ dysfunction. The focus will be on the effects of microbiome modulation during experimental acute kidney injury (excluding septic acute kidney injury) and comparison with other experimental acute organ injuries commonly seen in critically ill patients.

Microbiome-Based Therapeutics for Salt-Sensitive Hypertension: A Scoping Review

The purpose of this scoping review was to provide a comprehensive understanding of the current knowledge concerning the gut microbiome and SCFAs as emerging treatments for salt-sensitive hypertension. Relevant animal and human studies were identified via PubMed through August 2024. Twenty-four human (n = 9) and animal (n = 15) trials were included. Most human studies were observational (n = 6), aiming to compare gut microbiota differences between hypertensive and normotensive individuals. Three human studies evaluated microbiome-based interventions either via a sodium-restricted diet (n = 2) or prebiotic supplementation (n = 1). Fifteen animal trials involving either mice or rats were identified, all of which were interventional. These included dietary changes (n = 9), probiotic treatments (n = 1), postbiotic primarily bacterial metabolites (n = 4), and live biotherapeutic products (n = 4). All interventions were effective in decreasing blood pressure. Microbiome-based therapies as biologic modifiers for salt-sensitive hypertension are emerging. Substantial knowledge gaps remain, warranting further research to fully explore this promising therapeutic avenue.

Cardiac energy metabolic disorder and gut microbiota imbalance: a study on the therapeutic potential of Shenfu Injection in rats with heart failure

Objective

To investigate the relationship between heart failure (HF) and gut microbiota-mediated energy metabolism, and to explore the role of Shenfu Injection in this process.

Materials and methods

In this study, Adriamycin-induced chronic heart failure (CHF) rat model was used and randomly divided into the blank control group (Normal, n = 9), HF control group (Model, n = 12), Shenfu Injection treatment group (SFI, n = 9), and positive drug control group (TMZ, n = 9). The changes in gut microbiota structure were analyzed by 16S rRNA high-throughput sequencing, the content of short-chain fatty acids (SCFAs) was detected by targeted metabolomics technology, and cardiac function and energy metabolism-related indicators were evaluated.

Results

Myocardial energy metabolism in HF rats was disordered, characterized by reduced fatty acid oxidation, enhanced anaerobic glycolysis of glucose, mitochondrial damage, and decreased ATP content; The gut microbiota of HF rats was imbalanced, with a reduction in beneficial bacteria, an increase in conditional pathogenic bacteria, and impaired intestinal barrier function; Both Shenfu Injection and trimetazidine improved myocardial energy metabolism and cardiac function, but Shenfu Injection was more significant in regulating gut microbiota and improving intestinal health; The production of SCFAs from the gut microbiota of HF rats increased, which may be closely related to myocardial energy metabolism; SCFAs-producing bacteria Akkermansia and Blautia played a key role in the development of HF, and their abundance was positively correlated with SCFAs content.

Conclusion

Shenfu Injection in treating HF may improve myocardial energy metabolism and intestinal health by regulating gut microbiota, especially the abundance of SCFAs-producing bacteria Akkermansia and Blautia, thereby exerting therapeutic effects. This provides theoretical support for treatment strategies based on gut microbiota.

Advancements in the Pathogenesis, Diagnosis, and Therapeutic Implications of Intestinal Bacteria

Intestinal bacteria form one of the most complex microbial communities in the human body, playing a crucial role in maintaining host health and contributing to the development of various diseases. Here, we provide a comprehensive overview of the composition and function of intestinal bacteria, the factors affecting their homeostasis, and their association and mechanisms with a range of diseases (e.g., inflammatory bowel diseases, colorectal cancer, metabolic diseases). Additionally, their advanced potential in disease diagnosis and treatment is highlighted. Therapies, such as chemotherapy, radiotherapy, and immunotherapy, are significantly impacted by intestinal bacteria, with research indicating that bacteria can enhance chemoimmunotherapy efficiency by affecting T cell recruitment and immune cell infiltration. Fecal microbiota transplantation has emerged as a promising option for treating recurrent Clostridium difficile infections and certain metabolic and neurological disorders. Gut bacteria-related serum metabolites serve as non-invasive indicators for diagnosing CRC, while fecal immunochemical tests offer promising applications in CRC screening. Future research is needed to better understand the causal relationships between intestinal bacteria and diseases, develop more precise diagnostic tools, and evaluate the effectiveness and safety of microbiome-targeted therapies in clinical treatment. This study provides deeper insights into the role of intestinal bacteria in human health and disease, providing a scientific basis for innovative therapeutic strategies that have the potential to transform the landscape of healthcare.

Navigating the microbial maze: unraveling the connection between gut microbiome and pediatric kidney and urinary tract disease

The gut microbiome is made up of trillions of bacteria, viruses, archaea, and microbes that play a significant role in the maintenance of normal physiology in humans. Recent research has highlighted the effects of the microbiome and its dysbiosis in the pathogenesis and maintenance of kidney disease, especially chronic kidney disease (CKD) and its associated cardiovascular disease. While studies have addressed the kidney-microbiome axis in adults, how dysbiosis may uniquely impact pediatric kidney disease patients is not well-established. This narrative review highlights all relevant studies focusing on the microbiome and pediatric kidney disease that were published between 7/2015 and 7/2023. This review highlights pediatric-specific considerations including growth and bone health as well as emphasizing the need for increased pediatric research. Understanding microbiome-kidney interactions may allow for novel, less invasive interventions such as dietary changes and the use of probiotics to improve preventive care and ameliorate long-term morbidity and mortality in this vulnerable population.

Short-Chain Fatty Acids: Promising Therapeutic Targets for Respiratory Syncytial Virus Infection

The intestinal microbiota is a complex community of organisms present in the human gastrointestinal tract, some of which can produce short-chain fatty acids (SCFAs) through the fermentation of dietary fiber. SCFAs play a major role in mediating the intestinal microbiota's regulation of host immunity and intestinal homeostasis. Respiratory syncytial virus (RSV) can cause an imbalance between anti-inflammatory and proinflammatory responses in the host. In addition, changes in SCFA levels and the structure of the intestinal microbiota have been observed after RSV infection. Therefore, there may be a link between SCFAs and RSV infection, and SCFAs are expected to be therapeutic targets for RSV infection.

Deciphering olfactory receptor binding mechanisms: a structural and dynamic perspective on olfactory receptors

Olfactory receptors, classified as G-protein coupled receptors (GPCRs), have been a subject of scientific inquiry since the early 1950s. Historically, investigations into the sensory mechanisms of olfactory receptors were often confined to behavioral characteristics in model organisms or the expression of related proteins and genes. However, with the development of cryo-electron microscopy techniques, it has gradually become possible to decipher the specific structures of olfactory receptors in insects and humans. This has provided new insights into the binding mechanisms between odor molecules and olfactory receptors. Furthermore, due to the rapid advancements in related fields such as computer simulations, the prediction and exploration of odor molecule binding to olfactory receptors have been progressively achieved through molecular dynamics simulations. Through this comprehensive review, we aim to provide a thorough analysis of research related to the binding mechanisms between odor molecules and olfactory receptors from the perspectives of structural biology and molecular dynamics simulations. Finally, we will provide an outlook on the future of research in the field of olfactory receptor sensory mechanisms.

Putting Nose into Reproduction: Influence of Nasal and Reproductive Odourant Signaling on Male Reproduction

Odourant receptors (ORs) are not restricted only to the nose, but also occur in many other organs and tissues, including the reproductive system. In fact, ORs are the most heavily expressed in testis than in any other extra-nasal tissue. Accumulating evidence suggests that olfactory and reproductive systems are both structurally and functionally linked and that these interconnections can influence various aspects of reproduction. In this article, we first review our current understanding of these interconnections and then collate accumulated evidence on the presence of ORs in the male reproductive system and sperm cells. We then investigate the potential role of female reproductive tract odourants in sperm chemotaxis and selection. Finally, since the existing evidence especially for sperm odor sensing capability and its physiological function are controversial, we also review potential reasons for the controversy and propose some ways to resolve the debate. Collectively, we conclude that reproductive odourant signaling may play an important, although currently largely unclear role in many key processes directly related to male fertility. However, since we lack holistic understanding of the functional significance of ORs and odor sensing pathways of the male reproductive system, more empirical research is warranted.

Changes in Microbiome in Patients with Kidney Injury after Allogeneic Hematopoietic Stem Cell Transplantation

Key Points

Changes in microbiome diversity index are common in patients with stem cell transplant. Changes in microbiome diversity do not explain the high incidence of AKI in patients with stem cell transplant.

Background

AKI is a common complication of allogeneic hematopoietic cell transplantation (allo-HCT) that increases the risk of mortality. By contrast, higher diversity of intestinal microbiota at the time of neutrophil engraftment has been associated with lower mortality. We aimed to better understand kidney outcomes in relation to changes in gut diversity in this patient population, hypothesizing that patients with lower microbiome diversity at baseline and at engraftment were at higher risk of developing kidney complications.

Methods

We performed a single-center retrospective study of 419 hematopoietic cell transplant recipients from 2014 to 2017 at our institution whose gut microbiota were analyzed. We defined AKI and CKD on the basis of Kidney Disease Improving Global Outcomes criteria and eGFR using the CKD Epidemiology Collaboration equation. We defined gut microbiome diversity using Shannon and Simpson reciprocal diversity indices, with higher levels indicating more diverse microbiota.

Results

Simpson reciprocal diversity index and Shannon diversity index were 21.8 (interquartile range [IQR], 13.7–35.2; range, 1.6–102.5) and 3.7 (IQR, 3.2–4.2; range, 0.7–5.2) in our cohort at baseline and 6.3 (IQR, 3.7–10.4) and 2.3 (IQR, 1.7–2.8) at periengraftment, respectively. Of the 419, 263 patients (63%) developed any grade AKI in 100 days after hematopoietic cell transplantation and 114 (27%) developed grade 2+ AKI. There were no significant differences in microbiome diversity at baseline or periengraftment in patients who developed post-transplant AKI or CKD, respectively, in comparison with those who did not develop kidney complications.

Conclusions

Our findings do not support the existence of a link between baseline or periengraftment gut diversity and the risk of development of AKI or CKD in patients undergoing allo-HCT. This study highlights the complex and multifactorial etiology of AKI in allo-HCT recipients and the need for additional prospective and mechanistic studies.

Yellow Fluorescent Protein Quenching Assay for Analyzing Odorant Receptor Activity

Odorant receptors (ORs), recognized as the largest subfamily of G protein-coupled receptors (GPCR), are increasingly identified as membrane proteins crucial not only in nasal but also in various extra-nasal biological processes. However, researching the functions of these extra-nasal ORs is challenging due to the limited availability of ligands, posing a significant barrier to comprehensive studies. Large-scale screening with in vitro assays, such as the halide-sensitive yellow fluorescent protein (YFP) quenching assay, is crucial for deorphanizing ORs. This protocol employs the YFP quenching assay to identify OR-ligand interactions, thereby advancing OR deorphanization research.

Image-Based cAMP Sensor Assay for Analyzing Odorant Receptor Activity

Odorant receptors (ORs), the largest subfamily of G-protein-coupled receptors (GPCRs), are transmembrane proteins essential for olfactory perception. Recent research has revealed their expression in nonolfactory tissues, highlighting their potential as novel drug targets. However, the functional analysis of ORs beyond nasal tissues is constrained by limited availability of suitable ligands. Conventional in vitro methods for studying OR-ligand interactions via cAMP often face challenges in large-scale applications. This protocol introduces an advanced cAMP assay employing the Pink Flamindo sensor, a cAMP fluorescence sensor that normally does not exhibit fluorescence but shows fluorescence when combined with cAMP. This enables the real-time visualization of OR-ligand interactions through an imaging-based method. This technique significantly aids in the deorphanization of ORs.

Gut microbiota-derived short-chain fatty acid suppresses the excitability of rat nociceptive secondary neurons via G-protein-coupled receptor 41 signaling

Short-chain free fatty acids (SCFAs) are generated by gut microbiota through anaerobic fermentation of dietary fibers. Although gut microbiota-derived SCFAs modulate voltage-gated Ca2+ channels via G-protein-coupled receptor 41 (GPR41) in isolated sympathetic ganglion neurons, the influence of SCFAs, specifically propionic acid (PA), on the excitability of nociceptive neurons under in vivo conditions has yet to be ascertained. In the current study we assessed whether systemic PA administration diminishes the excitability of nociceptive trigeminal spinal nucleus caudalis (SpVc) wide-dynamic range neurons responding to mechanical stimulation. Extracellular single-unit recordings from SpVc wide-dynamic range neurons were performed in anesthetized rats after mechanical stimulation of the orofacial region. PA significantly and reversibly inhibited the mean firing frequency of SpVc neurons in response to both non-noxious and noxious mechanical stimuli in a dose-dependent manner. Simultaneous administration of a GPR41 inhibitor abolished the PA-induced inhibited firing rate of SpVc neurons, indicating that systemic PA decreased the excitability of nociceptive secondary trigeminal neurons by activating GPR41 signaling-mediated inhibition of voltage-gated Ca2+ channels in the central terminals of the SpVc. Modulation of trigeminal nociception by systemic SCFA administration indicates that gut microbiota-derived SCFAs could be effective analgesic agents for relieving trigeminal pain, creating a new therapeutic strategy for the management of trigeminal pain, including clinical pain.

Causal Associations Between the Gut Microbiota and Hypertension-Related Traits Through Mendelian Randomization: A Cross-Sectional Cohort Study

Previous studies have suggested a link between the gut microbiome and hypertension-related traits like blood pressure. However, these reports are often limited by weak causal evidence. This study investigates the potential causal association between gut microbiota and hypertension-related traits using Mendelian randomization with summary data from genome-wide association studies. The inverse-variance weighted method revealed that the Clostridium innocuum group (Odds ratio [OR]: 1.0047, 95% confidence interval [CI]: 1.0004-1.0090, p = 0.0336), Eubacterium fissicatena group (OR: 1.0047, 95% CI: 1.0005-1.0088, p = 0.0266), Lachnospiraceae FCS020 group (OR: 1.0063, 95% CI: 1.0004-1.0122, p = 0.0361), and Olsenella (OR: 1.0044, 95% CI: 1.0001-1.0088, p = 0.0430) were associated with an increased risk of hypertension. Conversely, Flavonifractor (OR: 0.9901, 95% CI: 0.9821-0.9982, p = 0.0166), Parabacteroides (OR: 0.9874, 95% CI: 0.9776-0.9972, p = 0.0121), and Senegalimassilia (OR: 0.9907, 95% CI: 0.9842-0.9974, p = 0.0063) were associated with a decreased risk of hypertension. External validation with the Guangdong Gut Microbiome Project confirmed a negative correlation between Parabacteroides and hypertension, potentially through metabolic pathways. These findings provide further evidence supporting the hypothesis that microbes and their metabolites play a role in blood pressure regulation.

Peripheral chemoreceptor, a new player in metabolic sensing during physical exertion: a hypothetical scenario

The cardiorespiratory and metabolic response to exercise has been associated with meeting the organism's metabolic demands during physical exertion. Of note, an incremental exercise is characterized by 1) cardiodynamic phase related to cardiac output enhancement mainly determined by a positive chronotropic response, 2) ventilatory threshold one, associated with a significant contribution of cardiovascular and pulmonary ventilation, and 3) ventilatory threshold two, correlated with a tremendous increase in breathing and metabolic responses to exercise. Notably, it has been shown that the ventilatory response to exercise increases concomitantly with the release and accumulation of metabolites (i.e., lactate released from skeletal muscle). The principal peripheral chemoreceptors are the carotid bodies (CBs), allocated into the carotid bifurcation and demonstrated to respond to several stimuli, triggering autonomic and ventilatory responses. Indeed, in past and recent years, it has been shown that CB could respond to lactate in in vitro and in vivo preparations, eliciting an increase in CB activity and ventilation. However, not all evidence indicates that peripheral chemoreceptors respond to lactate. Thus, considering that CB chemoreceptors' role in lactate-dependent breathing response is not completely clear and their potential preponderance as metabolic sensors during exercise has not been thoroughly explored, the present review was focused on the possible role of CB chemoreceptors as metabolic sensors during physical exertion in a physiological context, proposing it as a new actor in exercise physiology.

Recent status and trends of innate immunity and the gut-kidney aixs in IgAN: A systematic review and bibliometric analysis

BACKGROUND

There is a significant global demand for precise diagnosis and effective treatment of IgA nephropathy (IgAN), with innate immunity, particularly the complement system, exerting a profound influence on its pathogenesis. Additionally, the gut-kidney axis pathway is vital in the emergence and development of IgAN.

METHODS

We conducted a comprehensive search in the Web of Science database, spanning from January 1, 2000 to December 18, 2023. The gathered literature underwent a visual examination through CiteSpace, VOSviewer, and Scimago Graphica to delve into authors, nations, organizations, key terms, and other pertinent elements.

RESULT

Between 2000 and 2023, a total of 720 publications were identified, out of which 436 publications underwent screening for highly relevant literature analysis. The average annual number of articles focusing on IgAN, innate immunity, and the gut-kidney axis is approximately 31, with an upward trend observed. In terms of research impact encompassing publication count and authorship, the United States emerged as the leading contributor. Prominent keywords included "complement", "activation", "microbe", "gut-kidney axis", "C4d deposition", "alternative pathway" and "B cells" along with other prospective hot topics.

CONCLUSION

The correlation between IgAN and innate immunity is a focal point in current scientific research. Recent literature underscores the significance of the gut-kidney axis, where intestinal microorganisms and metabolites may influence IgAN. The complement system, a key component of innate immunity, also has a crucial function.Advancements in prevention, diagnosis, and treatment hinge on unraveling this intricate relationship.

Olfactory Receptors and Aortic Aneurysm: Review of Disease Pathways

Aortic aneurysm, the pathological dilatation of the aorta at distinct locations, can be attributed to many different genetic and environmental factors. The resulting pathobiological disturbances generate a complex interplay of processes affecting cells and extracellular molecules of the tunica interna, media and externa. In short, aortic aneurysm can affect processes involving the extracellular matrix, lipid trafficking/atherosclerosis, vascular smooth muscle cells, inflammation, platelets and intraluminal thrombus formation, as well as various endothelial functions. Many of these processes are interconnected, potentiating one another. Newer discoveries, including the involvement of odorant olfactory receptors in these processes, have further shed light on disease initiation and pathology. Olfactory receptors are a varied group of G protein coupled-receptors responsible for the recognition of chemosensory information. Although they comprise many different subgroups, some of which are not well-characterized or identified in humans, odorant olfactory receptors, in particular, are most commonly associated with recognition of olfactory information. They can also be ectopically localized and thus carry out additional functions relevant to the tissue in which they are identified. It is thus the purpose of this narrative review to summarize and present pathobiological processes relevant to the initiation and propagation of aortic aneurysm, while also incorporating evidence associating these ectopically functioning odorant olfactory receptors with the overall pathology.

The role for ω-3 polyunsaturated and short chain fatty acids in hypertension: An updated view on the interaction with gut microbiota

As of 2024, arterial hypertension is still considered the leading modifiable cardiovascular risk factor and, due to high rates of undertreatment and poor blood pressure control, the major contributor to human morbidity and mortality. Development of new treatment options and better interventions in lifestyle correction have become a priority of experimental and clinical research. In the last decades, dietary supplementation of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) and generation of gut microbiota-derived short chain fatty acids (SCFAs) have surged as potential and promising interventions for hypertension and cardiovascular prevention. ω-3 PUFAs are considered "essential" fatty acids that can be obtained only from dietary sources. Although previous intervention trials were not consistent in reporting a significant benefit of ω-3 PUFAs, the recent REDUCE-IT trial has provided robust evidence in support of their role in cardiovascular prevention. Recent studies have also identified the intestinal microbiota as a potential player in the pathophysiology and progression of hypertension. Although this might occur through many pathways, generation of SCFAs that is highly dependent on dietary fiber intake is primarily involved, providing an additional target for the development of novel therapeutic strategies. For these reasons, some scientific societies currently recommend dietary supplementation of ω-3 PUFAs and fiber-containing foods in patients with hypertension. In this narrative review, we summarize the results of studies that examined the effects of ω-3 PUFAs and SCFAs on blood pressure, highlighting the mechanisms of action on the vascular system and their possible impact on hypertension, hypertension-related organ damage and, ultimately, cardiovascular outcomes.

Comprehensive Transcriptomic Analysis Reveals Cell-Type-Specific Roles of Human Odorant Receptors in Glioblastoma and the Tumor Microenvironment

Odorant receptors (ORs), which constitute approximately 50% of all human G protein-coupled receptors, are increasingly recognized for their diverse roles beyond odor perception, including functions in various pathological conditions like brain diseases and cancers. However, the roles of ORs in glioblastoma (GBM), the most aggressive primary brain tumor with a median survival of only 15 months, remain largely unexplored. Here, we performed an integrated transcriptomic analysis combining The Cancer Genome Atlas RNA-seq and single-cell RNA sequencing data from GBM patients to uncover cell-type-specific roles of ORs within the tumor and its microenvironment. Our findings reveal that ORs display distinct expression patterns, with OR51E1 enriched in pericytes linked to vascular remodeling and angiogenesis, OR2B11 associated with tumor-associated macrophages supporting immunosuppressive phenotypes, and OR2L13 correlated with synaptic activity in recurrent tumors, potentially mediating treatment-induced neuronal adaptations. These results highlight ORs as potential therapeutic targets, offering new insights into their regulatory roles in GBM progression, immune modulation, and treatment resistance.

Research progress of gut microbiome and diabetic nephropathy

Diabetic nephropathy is an important complication of diabetic microvascular injury, and it is also an important cause of end-stage renal disease. Its high prevalence and disability rate significantly impacts patients' quality of life while imposing substantial social and economic burdens. Gut microbiota affects host metabolism, multiple organ functions, and regulates host health throughout the life cycle. With the rapid development of technology, researchers have found that gut microbiota is closely related to the progression of diabetic kidney disease. This review explores the role of gut microbiome in diabetic nephropathy summarizing proposed mechanisms of progression and focusing on microbial metabolites, intestinal barrier disruption, inflammation, filtration barrier damage and renal fibrosis. This review also examines the mechanism and limitations of current treatments, including drugs, fecal microbiota transplantation, and lifestyle changes, offering new perspectives on prevention and treatment.

Targeting Odorant Receptors in Adipose Tissue with Food-Derived Odorants: A Novel Approach to Obesity Treatment

Odorant receptors (ORs) have long been thought to serve as chemosensors located on the cilia of olfactory sensory neurons (OSNs) in the olfactory epithelium, where they recognize odorant molecules and comprise the largest family of seven transmembrane-domain G protein-coupled receptors (GPCRs). Over the last three decades, accumulating evidence has suggested that ORs are distributed in a variety of peripheral tissues beyond their supposed typical tissue expression in the olfactory epithelium. These ectopic ORs play a role in regulating various cellular, physiological, and pathophysiological phenomena in the body, such as regulation of hypertension, hepatic glucose production, cancer development, and chronic skin disease. Adipose tissue, the key organ in regulating obesity and energy metabolism, has been reported to take advantage of ectopic OR-mediated signaling. In this review, we summarize and provide an in-depth analysis of the current research on the key biological functions of adipose tissue ORs in response to food-derived odorants, as well as the molecular mechanisms underlying their activity.

Gut microbiota and healthy longevity

Recent progress on the underlying biological mechanisms of healthy longevity has propelled the field from elucidating genetic modification of healthy longevity hallmarks to defining mechanisms of gut microbiota influencing it. Importantly, the role of gut microbiota in the healthy longevity of the host may provide unprecedented opportunities to decipher the plasticity of lifespan on a natural evolutionary scale and shed light on using microbiota-targeted strategies to promote healthy aging and combat age-related diseases. This review investigates how gut microbiota affects healthy longevity, focusing on the mechanisms through which gut microbiota modulates it. Specifically, we focused on the ability of gut microbiota to enhance the intestinal barrier integrity, provide protection from inflammaging, ameliorate nutrientsensing pathways, optimize mitochondrial function, and improve defense against age-related diseases, thus participating in enhancing longevity and healthspan.

Endoplasmic reticulum stress in intestinal microecology: A controller of antineoplastic drug-related cardiovascular toxicity

Endoplasmic reticulum (ER) stress is extensively studied as a pivotal role in the pathological processes associated with intestinal microecology. In antineoplastic drug treatments, ER stress is implicated in altering the permeability of the mechanical barrier, depleting the chemical barrier, causing dysbiosis, exacerbating immune responses and inflammation in the immune barrier. Enteric dysbiosis and intestinal dysfunction significantly affect the circulatory system in various heart disorders. In antineoplastic drug-related cardiovascular (CV) toxicity, ER stress constitutes a web of relationships in the host-microbiome symbiotic regulatory loop. Therefore, understanding the holobiont perspective will help de-escalate spatial and temporal restrictions. This review investigates the role of ER stress-mediated gut microecological alterations in antineoplastic treatment-induced CV toxicity.

Microbial metabolite-receptor interactions in the gut microbiome

The gut microbiome impacts many physiological processes that greatly influence host health and disease. Metabolites produced by the gut microbiota have emerged as central players in regulating these biological pathways, often through the engagement of specific host receptors. Despite the importance of these microbial metabolites and receptors in human biology, the vast majority of these interactions remain uncharted due to the complex nature of the gut microbiome and the multitude of metabolites that these microbes produce. Here, we highlight recent developments in identifying such host-gut microbiota interactions, including characterization of bioactive metabolites and their mechanisms of action. Understanding these pathways will enable the development of prophylactics and therapeutics for treating many inflammatory diseases that are impacted by the gut microbiota.

Unraveling the Role of the Human Gut Microbiome in Health and Diseases

The human gut is a complex ecosystem that supports billions of living species, including bacteria, viruses, archaea, phages, fungi, and unicellular eukaryotes. Bacteria give genes and enzymes for microbial and host-produced compounds, establishing a symbiotic link between the external environment and the host at both the gut and systemic levels. The gut microbiome, which is primarily made up of commensal bacteria, is critical for maintaining the healthy host's immune system, aiding digestion, synthesizing essential nutrients, and protecting against pathogenic bacteria, as well as influencing endocrine, neural, humoral, and immunological functions and metabolic pathways. Qualitative, quantitative, and/or topographic shifts can alter the gut microbiome, resulting in dysbiosis and microbial dysfunction, which can contribute to a variety of noncommunicable illnesses, including hypertension, cardiovascular disease, obesity, diabetes, inflammatory bowel disease, cancer, and irritable bowel syndrome. While most evidence to date is observational and does not establish direct causation, ongoing clinical trials and advanced genomic techniques are steadily enhancing our understanding of these intricate interactions. This review will explore key aspects of the relationship between gut microbiota, eubiosis, and dysbiosis in human health and disease, highlighting emerging strategies for microbiome engineering as potential therapeutic approaches for various conditions.

Recent advancements in targeting the immune system to treat hypertension

Hypertension is the key leading risk factor for death globally, affecting ∼1.3 billion adults, particularly in low- and middle-income countries. Most people living with hypertension have uncontrolled high blood pressure, increasing their likelihood of cardiovascular events. Significant issues preventing blood pressure control include lack of diagnosis, treatment, and response to existing therapy. For example, monotherapy and combination therapy are often unable to lower blood pressure to target levels. New therapies are urgently required to tackle this issue, particularly those that target the mechanisms behind hypertension instead of treating its symptoms. Acting via an increase in systemic and tissue-specific inflammation, the immune system is a critical contributor to blood pressure regulation and is considered an early mechanism leading to hypertension development. Here, we review the immune system's role in hypertension, evaluate clinical trials that target inflammation, and discuss knowledge gaps in pre-clinical and clinical data. We examine the effects of anti-inflammatory drugs colchicine and methotrexate on hypertension and evaluate the blockade of pro-inflammatory cytokines IL-1β and TNF-α on blood pressure in clinical trials. Lastly, we highlight how we can move forward to target specific components of the immune system to lower blood pressure. This includes targeting isolevuglandins, which accumulate in dendritic cells to promote T cell activation and cytokine production in salt-induced hypertension. We discuss the potential of the dietary fibre-derived metabolites short-chain fatty acids, which have anti-inflammatory and blood pressure-lowering effects via the gut microbiome. This would limit adverse events, leading to improved medication adherence and better blood pressure control.

Ambient PMs pollution, blood pressure, potential mediation by short-chain fatty acids: A prospective panel study of young adults in China

BACKGROUND

The concurrent effects of particulate matter (PM) on both blood pressure (BP) and short-chain fatty acids (SCFAs) are insufficiently explored, with limited research on the potential mediating roles of SCFAs.

METHODS

In this prospective panel study with 4 follow-ups, we recruited 40 college students in Hefei, China, to assess the impacts of short-term exposure to PM (aerodynamic diameter ≤10 μm (PM10), ≤2.5 μm (PM2.5), and ≤1 μm (PM1)) on BP and SCFAs, along with potential mechanisms. Real-time PM data, urinary SCFAs levels, and BP indicators were systematically collected. Linear mixed-effects models assessed the relationships between PM, SCFAs, and BP. Mediation analyses explored SCFAs' mediating role in the PM-BP association.

RESULTS

PM exposure was positively linked to BP and negatively associated with SCFAs. For a 10 μg/m3 rise in PM10 at lag 0-72 h, there were notable reductions of 0.0019 % (95 %CI: -0.0028, -0.0010) in Acetic acid, 0.0262 % (-0.0369, -0.0155) in Propionic acid, and 0.0702 % (-0.1025, -0.0378) in Butyric acid. Systolic BP, diastolic BP, and mean arterial pressure (MAP) increased by 2.60 mmHg (0.96, 4.25), 2.24 mmHg (1.18, 3.31), and 2.36 mmHg (1.20, 3.53), respectively, per 10-μg/m3 rise in PM1 at lag 0-24 h. Decreased SCFAs levels explained significant portions (24.69-31.80 %) of the elevated MAP due to PM10. Stronger associations were found in females and individuals with abnormal BMI.

CONCLUSIONS

Our study shows that PM exposure decreases urinary SCFAs levels, which partially mediate the impact of PM on elevated BP. These findings enhance our comprehension of the pathways linking PM exposure to BP changes.

The association between circulating short-chain fatty acids and blood pressure in Chinese elderly population

The gut microbiome primarily generates short-chain fatty acids (SCFAs) by fermenting dietary fibers. Though previous studies have linked SCFAs to blood pressure, there remains a lack of research on the relationship between SCFAs levels in the serum of elderly individuals and blood pressure. Based on this, we investigated the associations of serum SCFAs with blood pressure in Chinese older adults in a cross-sectional study. In this report, we recruited 1013 older adults over 60 years of age from June to September 2016 in Lu 'an City, China. Using Ultra High Performance Liquid Chromatography-Quadrupole-Exactive-Orbitrap-Mass Spectrometry (UHPLC-QE-Orbitrap MS), we measured the level of various SCFAs, including acetic acid (AA), propanoic acid (PA), butyric acid (BA), isobutyric acid (iso-BA), valeric acid (VA), isovaleric acid (iso-VA), and caproic acid (CA), in serum samples collected from Chinese elderly adults. The study recruited 1013 older adults in total. Multiple logistic regression analysis shows that AA (OR = 0.696, 95%CI: 0.501-0.966) and VA (OR = 0.713, 95%CI: 0.516-0.985) are negatively associated with hypertension. Linear regression analysis shows a negative correlation between AA (β = -3.89, 95% CI: -7.12 - -0.66) and the systolic blood pressure (SBP) levels, and a significant negative association between iso-VA (β = -2.11, 95% CI: -3.94 - -0.29) and diastolic blood pressure (DBP) levels. Whether in unadjusted or adjusted linear regression models, we all observe significant positive associations between CA and blood pressure levels. In the Bayesian kernel-machine regression (BKMR) models, the trends between the mixture of SCFAs and hypertension, SBP are inverse, but not significant; we also observe a significant negative correlation between AA and SBP, and a significant negative association between iso-VA and DBP levels, while CA is significantly positively correlated with SBP and DBP. Collectively, our results advocate for considering SCFA as a potential intervention to lower blood pressure, and especially AA may be a possible target for research. This may provide new perspectives for understanding the role of SCFAs in hypertension.

Type III Secretion System in Intestinal Pathogens and Metabolic Diseases

Modern lifestyle changes, especially the consumption of a diet high in salt, sugar, and fat, have contributed to the increasing incidence and prevalence of chronic metabolic diseases such as diabetes, obesity, and gout. Changing lifestyles continuously shape the gut microbiota which is closely related to the occurrence and development of metabolic diseases due to its specificity of composition and structural diversity. A large number of pathogenic bacteria such as Yersinia, Salmonella, Shigella, and pathogenic E. coli in the gut utilize the type III secretion system (T3SS) to help them resist host defenses and cause disease. Although the T3SS is critical for the virulence of many important human pathogens, its relationship with metabolic diseases remains unknown. This article reviews the structure and function of the T3SS, the disruption of intestinal barrier integrity by the T3SS, the changes in intestinal flora containing the T3SS in metabolic diseases, the possible mechanisms of the T3SS affecting metabolic diseases, and the application of the T3SS in the treatment of metabolic diseases. The aim is to provide insights into metabolic diseases targeting the T3SS, thereby serving as a valuable reference for future research on disease diagnosis, prevention, and treatment.

Engineered odorant receptors illuminate the basis of odour discrimination

How the olfactory system detects and distinguishes odorants with diverse physicochemical properties and molecular configurations remains poorly understood. Vertebrate animals perceive odours through G protein-coupled odorant receptors (ORs)1. In humans, around 400 ORs enable the sense of smell. The OR family comprises two main classes: class I ORs are tuned to carboxylic acids whereas class II ORs, which represent most of the human repertoire, respond to a wide variety of odorants2. A fundamental challenge in understanding olfaction is the inability to visualize odorant binding to ORs. Here we uncover molecular properties of odorant-OR interactions by using engineered ORs crafted using a consensus protein design strategy3. Because such consensus ORs (consORs) are derived from the 17 major subfamilies of human ORs, they provide a template for modelling individual native ORs with high sequence and structural homology. The biochemical tractability of consORs enabled the determination of four cryogenic electron microscopy structures of distinct consORs with specific ligand recognition properties. The structure of a class I consOR, consOR51, showed high structural similarity to the native human receptor OR51E2 and generated a homology model of a related member of the human OR51 family with high predictive power. Structures of three class II consORs revealed distinct modes of odorant-binding and activation mechanisms between class I and class II ORs. Thus, the structures of consORs lay the groundwork for understanding molecular recognition of odorants by the OR superfamily.

Flavonoids, gut microbiota and cardiovascular disease: Dynamics and interplay

Cardiovascular disease (CVD) remains the leading cause of global morbidity and mortality. Extensive efforts have been invested to explicate mechanisms implicated in the onset and progression of CVD. Besides the usual suspects as risk factors (obesity, diabetes, and others), the gut microbiome has emerged as a prominent and essential factor in the pathogenesis of CVD. With its endocrine-like effects, the microbiome modulates many physiologic processes. As such, it is not surprising that dysbiosis-by generating metabolites, inciting inflammation, and altering secondary bile acid signaling- could predispose to or aggravate CVD. Nevertheless, various natural and synthetic compounds have been shown to modulate the microbiome. Prime among these molecules are flavonoids, which are natural polyphenols mainly present in fruits and vegetables. Accumulating evidence supports the potential of flavonoids in attenuating the development of CVD. The ascribed mechanisms of these compounds appear to involve mitigation of inflammation, alteration of the microbiome composition, enhancement of barrier integrity, induction of reverse cholesterol transport, and activation of farnesoid X receptor signaling. In this review, we critically appraise the methods by which the gut microbiome, despite being essential to the human body, predisposes to CVD. Moreover, we dissect the mechanisms and pathways underlying the cardioprotective effects of flavonoids.

Metformin modulates microbiota and improves blood pressure and cardiac remodeling in a rat model of hypertension

AIMS

Metformin has been attributed to cardiovascular protection even in the absence of diabetes. Recent observations suggest that metformin influences the gut microbiome. We aimed to investigate the influence of metformin on the gut microbiota and hypertensive target organ damage in hypertensive rats.

METHODS

Male double transgenic rats overexpressing the human renin and angiotensinogen genes (dTGR), a model of angiotensin II-dependent hypertension, were treated with metformin (300 mg/kg/day) or vehicle from 4 to 7 weeks of age. We assessed gut microbiome composition and function using shotgun metagenomic sequencing and measured blood pressure via radiotelemetry. Cardiac and renal organ damage and inflammation were evaluated by echocardiography, histology, and flow cytometry.

RESULTS

Metformin treatment increased the production of short-chain fatty acids (SCFA) acetate and propionate in feces without altering microbial composition and diversity. It significantly reduced systolic and diastolic blood pressure and improved cardiac function, as measured by end-diastolic volume, E/A, and stroke volume despite increased cardiac hypertrophy. Metformin reduced cardiac inflammation by lowering macrophage infiltration and shifting macrophage subpopulations towards a less inflammatory phenotype. The observed improvements in blood pressure, cardiac function, and inflammation correlated with fecal SCFA levels in dTGR. In vitro, acetate and propionate altered M1-like gene expression in macrophages, reinforcing anti-inflammatory effects. Metformin did not affect hypertensive renal damage or microvascular structure.

CONCLUSION

Metformin modulated the gut microbiome, increased SCFA production, and ameliorated blood pressure and cardiac remodeling in dTGR. Our findings confirm the protective effects of metformin in the absence of diabetes, highlighting SCFA as a potential mediators.