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Integrated Inflammatory and Gut Microbial Signatures in Major Depressive Disorder: A Case-Control Study

Nour Dabboussi1,2, Espérance Debs3, Marc Bouji4

  • 1Laboratory of Research in Physiology and Pathophysiology, Faculty of Medicine, Saint Joseph University of Beirut, Beirut 1107 2020, Lebanon.

Brain Sciences
|July 28, 2026
PubMed
Abstract

Insights

Major depressive disorder (MDD) is linked to specific gut bacteria, not systemic inflammation, in Lebanese adults. This study highlights potential microbial targets for understanding depression and the gut-brain axis.

Area of Science:

  • Neuroscience
  • Microbiology
  • Psychiatry

Background:

  • Major depressive disorder (MDD) involves inflammation and the microbiota-gut-brain axis.
  • Limited data exists on neuroimmune-microbiome interactions in depression, especially in Middle Eastern and North African (MENA) populations.
  • Diet's role in these interactions remains under-explored in depression.

Purpose of the Study:

  • To investigate associations between MDD, systemic inflammatory markers, and gut microbiota composition in Lebanese adults.
  • To address the scarcity of research on these interactions within the MENA region.
  • To explore potential diet-influenced neuroimmune-microbiome links in depression.

Main Methods:

  • Cross-sectional case-control study involving 46 adults with MDD and 25 healthy controls.
  • Measured plasma C-reactive protein (CRP) and interleukin-6 (IL-6).
  • Characterized gut microbiota using 16S rRNA gene sequencing, adjusting for BMI, diet, and medication.

Main Results:

  • MDD was not independently associated with CRP or IL-6; BMI was a key inflammation determinant.
  • MDD showed enrichment of specific genera (e.g., Dorea, Collinsella) and depletion of others (e.g., Christensenella).
  • No difference in alpha diversity; beta diversity showed modest differences.

Conclusions:

  • Specific gut microbial taxa may influence gut-brain signaling in MDD.
  • These findings suggest potential microbial targets for understanding MDD and systemic inflammation.
  • Further longitudinal and mechanistic studies are needed to confirm causality.
Keywords:
16S rRNA sequencingC-reactive proteinLebanese populationgut microbiotainflammationinterleukin-6major depressive disorder

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