Palmitic acid and trans-4-hydroxy-3-methoxycinnamate, the active ingredients of Yaobishu formula, reduce inflammation and pain by regulating gut microbiota and metabolic changes after lumbar disc herniation to activate autophagy and the Wnt/β-catenin pathway

Causal Relationship Between Gut Microbiota, Blood Metabolites, and Intervertebral Disc Degeneration: A Two-Step, Two-Sample Bidirectional Mendelian Randomization Study

Background

Some studies have shown that gut microbiota may be associated with intervertebral disc degeneration. However, the causal effects between gut microbiota and IVDD and whether blood metabolites act as a mediator remain unclear. The objective of this study was to investigate the causal relationship between gut microbiota and intervertebral disc herniation, with a focus on the potential mediating role of blood metabolites.

Methods

Gut microbiota, blood metabolites, and IVDD data were identified from large-scale genome-wide association studies (GWAS) summary data. Then we used Mendelian randomization analysis to investigate the causal relationships between gut microbiota, blood metabolites, and intervertebral disc degeneration, using the inverse variance-weighted method as the primary outcome measure. Subsequently, we conducted sensitivity analyses to ascertain the robustness of the results by testing for heterogeneity and horizontal pleiotropy. In addition, we explored blood metabolites as a mediating factor in the pathway from gut microbiota to IVDD.

Results

We identified 6 taxa that were strongly associated with the incidence of intervertebral disc herniation. There were 8 positive and 13 negative causal effects between genetic liability in the blood metabolites and IVDD. The mediation analysis revealed that the connections among genus Comamonas B, family Halomonadaceae, family UBA6960, and IVDD were mediated by ADP to glycine ratio, 1,3-dimethylurate levels, 3-hydroxy-2-methylpyridine sulfate levels, and Histidine levels. Each of these accounted for 7.77%, 9.04%, 12.56%, and 11.76%, respectively.

Conclusions

Our study provides evidence supporting a potential causal relationship between certain microbial taxa and intervertebral disc degeneration. This study focuses on the mediation of specific blood metabolites, which suggests that they may represent potential targets for intervention.

Exploring the role of gut microbiota in intervertebral disc degeneration: insights from bidirectional Mendelian randomization analysis

OBJECTIVE

Although previous studies have indicated a potential association between the gut microbiota and intervertebral disc degeneration (IVDD), the precise nature of this relationship remains unclear. The objective of this study is to further explore the potential causal relationship between gut microbiota and IVDD using a bidirectional Mendelian randomization approach, with the aim of identifying potential microbial characteristics associated with IVDD.

METHODS

Using the data from genome-wide association studies (GWAS) involving 412 gut microbiota species and 227,388 controls and 29,508 cases of IVDD. Inverse variance weighted (IVW) was used as the primary Mendelian randomization (MR) analysis, complemented by weighted median, MR-Egger regression, weighted mode and simple mode methods. Extensive sensitivity analyses were performed to confirm the robustness of the results and to assess heterogeneity and horizontal pleiotropy.

RESULTS

This study revealed a positive genetic predisposition between 6 types of gut microbiota and IVDD through the IVW method, indicating that increased levels of these microbiota may lead to a higher risk of IVDD. Conversely, 6 types of gut microbiota were found to have negative effects on IVDD, suggesting that increased levels of these microbiota may have a protective effect against IVDD. Reverse MR analysis results revealed such possibilities as 1 positive and 5 negative causal relationships between IVDD and gut microbiota. The results of Cochran's Q test, MR-Egger regression, and MR-PRESSO analysis from the bidirectional Mendelian randomization all yielded p-values greater than 0.05, indicating that there is no significant heterogeneity or pleiotropy in the genetic effect analysis between gut microbiota and IVDD.

CONCLUSION

We used a bidirectional Mendelian randomization approach to identify various gut microbiota associated with IVDD. Our findings lay the foundation for further exploration of the pathogenesis and treatment strategies of gut microbiota and IVDD, and provide new possibilities for research on biomarkers of IVDD-related metabolic microbiota.

A Mendelian randomization study to reveal gut-disc axis: causal associations between gut microbiota with intervertebral disc diseases

PURPOSE

Emerging evidence suggests a link between gut microbiota and intervertebral disc diseases (IDDs); however, the causal relationships remain unclear. This study aimed to evaluate the causal effects of gut microbiota on the risk of cervical disc disorders (CDD), other intervertebral disc disorders (OIDD), pyogenic intervertebral disc infections, and discitis, shedding light on the potential "gut-disc axis".

METHODS

Genetic variation data for 202 gut microbiota taxa were obtained from the Dutch Microbiome Project, and disease outcome data were sourced from the FinnGen consortium. A Mendelian Randomization (MR) approach was employed to assess causal relationships, using genetic variants as instrumental variables. Sensitivity analyses, including tests for pleiotropy, heterogeneity, and reverse causation, ensured robust findings.

RESULTS

The study identified 20 gut microbial taxa with significant associations to IDDs. Notably, taxa within the Erysipelotrichaceae family showed consistent protective effects against OIDD after Bonferroni correction (P < 0.05). Associations between several species and specific diseases, such as Alistipes senegalensis with CDD and Ruminococcus lactaris with discitis, were also observed. Sensitivity analyses confirmed no evidence of confounding or reverse causation.

CONCLUSION

This study provides evidence of causal relationships between specific gut microbiota and IDDs, supporting the existence of a "gut-disc axis." The findings suggest that microbial dysbiosis may influence spinal health through systemic inflammation and immune regulation. These insights open new possibilities for microbiota-targeted interventions, such as probiotics or dietary modifications, to prevent or manage IDDs. However, further research is required to validate these therapeutic strategies.

FOXG1 interaction with SATB2 promotes autophagy to alleviate neuroinflammation and mechanical abnormal pain in rats with lumbar disc herniation

BACKGROUND

Most patients with lumbar disc herniation can be relieved or cured by surgical or non-surgical treatment; however, postoperative persistent radiculopathy is common. This study demonstrates the regulation of autophagy by the FOXG1/SATB2 axis in lumbar disc herniation (LDH).

METHODS

Rat dorsal root neurons were induced with TNF-α in vitro. Sprague Dawley (SD) rats were used to construct the LDH rat model, which was treated with L. paracasei S16 or oe-FOXG1. Paw withdrawal threshold or latency assay (PWT/L) was performed. Peripheral blood samples were collected and analysed using ELISA and miRNAseq. RT-qPCR was used to analyse the expression of FOXG1, LC3B, Beclin1, p62, and SATB2. TUNEL staining and flow cytometry were used to analyse apoptosis. The expression of Cyclin D1, PCNA, Ki67, FOXG1, SATB2, and autophagy proteins was measured using western blotting.

RESULTS

TNF-α induced low expression of FOXG1 and SATB2 in dorsal root ganglion (DRG) neurons of rats. TNF-α induced an increase in p62 protein and a decrease in LC3II/I and Beclin-1 proteins in neurons, which were blocked by oe-FOXG1. oe-FOXG1 suppressed inflammation and apoptosis in TNF-α-induced DRG neurons and LDH rats and promoted the expression of Cyclin D1, PCNA, and Ki67. Many miRNAs were increased in the peripheral blood of LDH rats, but decreased after L. paracasei S16 intervention. L. paracasei S16 affects miR-31a-5p and SATB2 expression. Dual luciferase reporter gene assay confirmed that miR-31a-5p bound to SATB2. Co-IP analysis confirmed the interaction between FOXG1 and SATB2. Silencing of SATB2 inhibited the beneficial effects of oe-FOXG1 in TNF-α-induced dorsal root ganglion neurons. Animal experiments further demonstrated that oe-FOXG1 improved LDH disease characteristics by downregulating PWT, PWL, inflammation, and apoptosis levels and upregulating SATB2-autophagy levels.

CONCLUSIONS

MiR-31a-5p/SATB2 is involved in the treatment of L. paracasei S16 in LDH rats. Overexpression of FOXG1 promotes autophagy through SATB2 to improve LDH levels This provides a new approach for the treatment of LDH.

Unveiling the Gut-Disc Axis: How Microbiome Dysbiosis Accelerates Intervertebral Disc Degeneration

The gut microbiome (GM), often referred to as the second genome of the human body, plays a crucial role in various metabolic processes and mediates the development of numerous diseases. Intervertebral disc degeneration (IDD) is an age-related degenerative spinal disease characterized by the loss of disc height, hydration, and integrity, leading to pain and reduced mobility. Although the pathogenesis of IDD is not fully understood, recent studies suggest that dysbiosis of the gut microbiome may accelerate the progression of IDD through multiple mechanisms. This article begins by discussing the potential relationship between GM dysbiosis and human diseases, followed by a comprehensive review of the regulatory mechanisms of GM in skeletal diseases within the gut-disc axis framework. Furthermore, it explores three potential pathways through which GM dysbiosis may mediate the development of IDD: immunomodulation, bacterial translocation and colonization, and the decomposition and absorption of intestinal metabolites. These pathways can disrupt disc cell homeostasis and promote degenerative changes. Finally, this paper summarizes for the first time the potential therapeutic approaches for delaying IDD by targeting the gut-disc axis, providing new insights into the pathogenesis and regenerative repair strategies for IDD.