Potential Therapeutic Effects of Short-Chain Fatty Acids on Chronic Pain

Differential cortical aspartate uptake across the oestrous cycle is associated with changes in gut microbiota in Wistar-Kyoto rats

Pain and psychological stress are intricately linked, with sex differences evident in disorders associated with both systems. Glutamatergic signalling in the central nervous system is influenced by gonadal hormones via the hypothalamic-pituitary-adrenal axis and is central in pain research. Emerging evidence supports an important role for the gut microbiota in influencing pain signalling. Here, the functional activity of excitatory amino acid transporters (EAATs) in the anterior cingulate cortex (ACC) and lumbosacral spinal cord of male and female Wistar-Kyoto rats, an animal model of comorbid visceral hypersensitivity and enhanced stress responsivity, was investigated across the oestrous cycle. Correlations between the gut microbiota and changes in the functional activity of the central glutamatergic system were also investigated. EAAT function in the lumbosacral spinal cord was similar between males and females across the oestrous cycle. EAAT function was higher in the ACC of dioestrus females compared to proestrus and oestrus females. In males, aspartate uptake in the ACC positively correlated with Bacteroides, while aspartate uptake in the spinal cord positively correlated with the relative abundance of Lachnospiraceae NK4A136. Positive associations with aspartate uptake in the spinal cord were also observed for Alistipes and Bifidobacterium during oestrus, and Eubacterium coprostanoligenes during proestrus. Clostridium sensu stricto1 was negatively associated with aspartate uptake in the ACC in males and dioestrus females. These data indicate that glutamate metabolism in the ACC is oestrous stage-dependent and that short-chain fatty acid-producing bacteria are positively correlated with aspartate uptake in males and during specific oestrous stages in females.

Role of Vitamin D Status and Alterations in Gut Microbiota Metabolism in Fibromyalgia-Associated Chronic Inflammatory Pain

Background/Objectives: Several studies suggest gut microbiota metabolites as important immuno-modulators in inflammatory pain. We aimed to investigate the relationship between vitamin D status and gut dysbiosis markers in fibromyalgia (FM)-associated chronic inflammation. Methods: Blood samples were collected from sixty-eight female FM patients (49.9 ± 12.35 years). Pain intensity was assessed by FIQ-R. The serum levels of the pro-inflammatory cytokines TNF-α, IL-1β, IL-6, IL-17, IFN-γ, as well as those of vitamin D (25(OH)D3) and the kynurenine/tryptophan ratio (Kyn/Trp) were determined by ELISA and HPLC, respectively. The plasma levels of the SCFAs acetate, butyrate, and propionate were detected by GC-MS. Results: A mean FIQ-R score indicated that the patients could be classified as having moderate FM. The mean levels of all cytokines, but IL-6 and IL-1β, were higher than the normal reference values. The highest concentrations of cytokines were observed in patients showing the highest FIQ-R scores and the lowest 25(OH)D3 levels. Deficient levels of acetate were found paralleled by an increase in Kyn/Trp. The highest acetate concentrations were detected in patients with the lowest FIQ-R scores and 25(OH)D3 levels. Significantly negative correlations were found between 25(OH)D3 concentrations and FIQ-R scores (p = 0.007) as well as IL-17 levels (p = 0.002) and between acetate and TNF-α (p = 0.040) as well as FIQ-R scores (p = 0.028), while significantly positive correlations were observed between Kyn/Trp and IL-17 (p = 0.027) as well as IFN-γ (p = 0.003). Conclusions: Our preliminary data suggest that the vitamin D status along with altered gut microbiota metabolism plays a major role in FM-related inflammatory pain. Replication of these findings in a larger cohort is required to provide additional insights.

Unlocking Cardioprotective Potential of Gut Microbiome: Exploring Therapeutic Strategies

The microbial community inhabiting the human gut resembles a bustling metropolis, wherein beneficial bacteria play pivotal roles in regulating our bodily functions. These microorganisms adeptly break down resilient dietary fibers to fuel our energy, synthesize essential vitamins crucial for our well-being, and maintain the delicate balance of our immune system. Recent research indicates a potential correlation between alterations in the composition and activities of these gut microbes and the development of coronary artery disease (CAD). Consequently, scientists are delving into the intriguing realm of manipulating these gut inhabitants to potentially mitigate disease risks. Various promising strategies have emerged in this endeavor. Studies have evidenced that probiotics can mitigate inflammation and enhance the endothelial health of our blood vessels. Notably, strains such as Lactobacilli and Bifidobacteria have garnered substantial attention in both laboratory settings and clinical trials. Conversely, prebiotics exhibit anti-inflammatory properties and hold potential in managing conditions like hypertension and hypercholesterolemia. Synbiotics, which synergistically combine probiotics and prebiotics, show promise in regulating glucose metabolism and abnormal lipid profiles. However, uncertainties persist regarding postbiotics, while antibiotics are deemed unsuitable due to their potential adverse effects. On the other hand, TMAO blockers, such as 3,3-dimethyl-1-butanol, demonstrate encouraging outcomes in laboratory experiments owing to their anti-inflammatory and tissue-protective properties. Moreover, fecal transplantation, despite yielding mixed results, warrants further exploration and refinement. In this comprehensive review, we delve into the intricate interplay between the gut microbiota and CAD, shedding light on the multifaceted approaches researchers are employing to leverage this understanding for therapeutic advancements.

Genetically predicted causal effects of gut microbiota on spinal pain: a two-sample Mendelian randomization analysis

Background

Observational studies have hinted at a correlation between the gut microbiota and spinal pain (SP). However, the impact of the gut microbiota on SP remains inconclusive.

Methods

In this study, we employed a two-sample Mendelian randomization (MR) analysis to explore the causal relationship between the gut microbiota and SP, encompassing neck pain (NP), thoracic spine pain (TSP), low back pain (LBP), and back pain (BP). The compiled gut microbiota data originated from a genome-wide association study (GWAS) conducted by the MiBioGen consortium (n = 18,340). Summary data for NP were sourced from the UK Biobank, TSP from the FinnGen Biobank, and LBP from both the UK Biobank and FinnGen Biobank. Summary data for BP were obtained from the UK Biobank. The primary analytical approach for assessing causal relationships was the Inverse Variance Weighted (IVW) method, supplemented by various sensitivity analyses to ensure result robustness.

Results

The IVW analysis unveiled 37 bacterial genera with a potential causal relationship to SP. After Benjamini-Hochberg corrected test, four bacterial genera emerged with a strong causal relationship to SP. Specifically, Oxalobacter (OR: 1.143, 95% CI 1.061-1.232, P = 0.0004) and Tyzzerella 3 (OR: 1.145, 95% CI 1.059-1.238, P = 0.0007) were identified as risk factors for LBP, while Ruminococcaceae UCG011 (OR: 0.859, 95% CI 0.791-0.932, P = 0.0003) was marked as a protective factor for LBP, and Olsenella (OR: 0.893, 95% CI 0.839-0.951, P = 0.0004) was recognized as a protective factor for low back pain or/and sciatica. No significant heterogeneity or horizontal pleiotropy was observed through alternative testing methods.

Conclusion

This study establishes a causal relationship between the gut microbiota and SP, shedding light on the "gut-spine" axis. These findings offer novel perspectives for understanding the etiology of SP and provide a theoretical foundation for potential interventions targeting the gut microbiota to prevent and treat SP.