Harvard researchers have found that M. morganii may contribute to depression by producing an inflammatory molecule.
- Biochemical analyses reveal how the gut bacterium Morganella morganii may contribute to some cases of major depressive disorder.
- The bacterium incorporates an environmental contaminant into one of its molecules, triggering inflammation — a known factor in disease development.
- These findings suggest the contaminant could serve as a biomarker and further support the idea that major depressive disorder may have autoimmune connections.
Reference: “Unusual Phospholipids from Morganella morganii Linked to Depression” by Sunghee Bang, Yern-Hyerk Shin, Sung-Moo Park, Lei Deng, R. Thomas Williamson, Daniel B. Graham, Ramnik J. Xavier and Jon Clardy, 16 January 2025, Journal of the American Chemical Society.
ABSTRACT: A multifactorial association study detected a probable causal connection between the prevalence of Morganella morganii in the gut microbiome and the incidence of major depressive disorder (MDD) in the human host. A bioassay-guided fractionation approach identified bacterially produced metabolites that induced pro-inflammatory immune responses. The metabolites are unusual phospholipids that resemble conventional cardiolipins, in which diethanolamine (DEA) replaces the central glycerol. These molecular chimeras of endogenous metabolites from phospholipid biosynthetic pathways and the industrially produced micropollutant DEA activate TLR2/TLR1 receptors and induce the production of pro-inflammatory cytokines, especially IL-6. Their activity in conventional immunomodulatory assays largely parallels that of immunogenic cardiolipins with conventional structures. The molecular mechanism connecting these chimeric cardiolipins to MDD is supported by other studies and has implications for conditions other than MDD.
DOI: 10.1021/jacs.4c15158 Link to the paper under discussion: https://pubs.acs.org/doi/10.1021/jacs.4c15158 PDF Link: https://pubs.acs.org/doi/epdf/10.1021/jacs.4c15158?ref=article_openPDF
Looks like IL-6 production is the mechanism of ramping up inflammatory response.