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Updated: Jun 18, 2025
Microbiota Analysis Using Two-step PCR and Next-generation 16S rRNA Gene Sequencing
Published on: October 15, 2019
Gut microbiota linked to hydrocephalus through inflammatory factors: a Mendelian randomization study
Yingjie Shen1, Changyu Li2, Xi Zhang1
1Department of Neurosurgery, National Health Commission Key Laboratory of Cell Transplantation, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.
Background:
The gut microbiota (GM) has been implicated in neurological disorders, but the relationship with hydrocephalus, especially the underlying mechanistic pathways, is unclear. Using Mendelian randomization (MR), we aim to discover the mediating role of inflammatory factors in the relationship between GM and hydrocephalus.
Methods:
After removing confounders, univariable and multivariable MR analyses were performed using summary statistics to assess the causal relationships between GM, inflammatory factors (IL-17A and IL-27), and types of hydrocephalus. Meta-analyses were used to reconcile the differences in MR results between different hydrocephalus sources. Finally, mediator MR analyses were applied to determine the mediating effect of inflammatory factors. Various sensitivity analysis methods were employed to ensure the reliability and stability of the results.
Results:
After correction for P-values, Firmicutes (phylum) (OR, 0.34; 95%CI, 0.17-0.69; P = 2.71E-03, P FDR = 2.44E-02) significantly reduced the risk of obstructive hydrocephalus. The remaining 18 different taxa of GM had potential causal relationships for different types of hydrocephalus. In addition, Firmicutes (phylum) decreased the risk of obstructive hydrocephalus by increasing levels of IL-17A (mediating effect = 21.01%), while Eubacterium ruminantium group (genus) increased the risk of normal-pressure hydrocephalus by decreasing levels of IL-27 (mediating effect = 7.48%).
Conclusion:
We reveal the connection between GM, inflammatory factors (IL-17A and IL-27), and hydrocephalus, which lays the foundation for unraveling the mechanism between GM and hydrocephalus.
Insights
The gut microbiota influences hydrocephalus risk. Certain bacteria, like Firmicutes, may reduce obstructive hydrocephalus risk by modulating IL-17A levels, while others impact normal-pressure hydrocephalus via IL-27.
Area of Science:
- Microbiome research
- Neurology
- Immunology
Background:
- The gut microbiota's role in neurological disorders is increasingly recognized.
- Specific mechanisms linking gut bacteria to hydrocephalus remain largely unexplored.
- Inflammatory factors may mediate the gut microbiota-hydrocephalus axis.
Purpose of the Study:
- To investigate the causal relationship between gut microbiota composition and hydrocephalus.
- To identify the mediating role of inflammatory factors, specifically IL-17A and IL-27, in this relationship.
- To elucidate potential mechanistic pathways between the gut microbiota and hydrocephalus.
Main Methods:
- Mendelian randomization (MR) analyses utilizing summary statistics.
- Assessment of causal links between gut microbiota taxa, IL-17A, IL-27, and hydrocephalus types.
- Mediator MR analyses to quantify the indirect effects of gut microbiota on hydrocephalus via inflammatory factors.
- Sensitivity analyses to ensure result robustness.
Main Results:
- The phylum Firmicutes was associated with a reduced risk of obstructive hydrocephalus (OR, 0.34; P=2.71E-03).
- Firmicutes decreased obstructive hydrocephalus risk by increasing IL-17A levels (mediating effect = 21.01%).
- The genus Eubacterium ruminantium group increased normal-pressure hydrocephalus risk by decreasing IL-27 levels (mediating effect = 7.48%).
Conclusions:
- Gut microbiota composition is causally linked to hydrocephalus risk.
- Inflammatory factors IL-17A and IL-27 mediate the relationship between specific gut bacteria and hydrocephalus.
- These findings provide a foundation for understanding the gut microbiota-brain axis in hydrocephalus pathogenesis.
