The gut microbiome in intravenous immunoglobulin-treated chronic inflammatory demyelinating polyneuropathy.

Background And Purpose: The gut microbiome is involved in autoimmunity. Data on its composition in chronic inflammatory demyelinating polyneuropathy (CIDP), the most common chronic autoimmune disorder of peripheral nerves, are currently lacking.

Methods: In this monocentric exploratory pilot study, stool samples were prospectively collected from 16 CIDP patients (mean age 58 ± 10 years, 25% female) before and 1 week after administration of intravenous immunoglobulin (IVIg). Gut microbiota were analyzed via bacterial 16S rRNA gene sequencing and compared to 15 age-matched healthy subjects (mean age 59 ± 15 years, 66% female).

Results: The gut microbiota of CIDP patients showed an increased alpha-diversity (p = 0.005) and enrichment of Firmicutes, such as Blautia (p = 0.0004), Eubacterium hallii (p = 0.0004), or Ruminococcus torques (p = 0.03), and of Actinobacteriota (p = 0.03) compared to healthy subjects. IVIg administration did not alter the gut microbiome composition in CIDP in this short-term observation (p = 0.95).

Conclusions: The gut microbiome in IVIg-treated CIDP shows distinct features, with increased bacterial diversity and enrichment of short-chain fatty acid producing Firmicutes. IVIg had no short-term impact on the gut microbiome in CIDP patients. As the main limitation of this exploratory pilot study was small cohort size, future studies also including therapy-naïve patients are warranted to verify our findings and to explore the impact of long-term IVIg treatment on the gut microbiome in CIDP.