Background: Evidence has implicated the translocation of commensal Gram-negative bacteria
(Gram-B) due to leaky gut in the pathophysiology of depression and physio-somatic symptoms (e.g.
fatigue, pain, irritable bowel syndrome, malaise, etc.). In addition, the leaky gut may contribute to immune-
inflammatory activation and oxidative stress. This study investigated whether bacterial translocation
is associated with perinatal depression and anxiety scores and with prenatal physio-somatic symptoms
and immune-inflammatory biomarkers, including the tryptophan catabolite (TRYCAT) pathway.
Method: Data were collected in pregnant women at the end of term (T1) and 4-6 weeks after delivery
(T2) as well as in non-pregnant controls. We examined the associations between serum IgM/IgA responses
to Gram-B at the end of term and depression (Edinburgh Postnatal Depression Scale -EPDS)
and anxiety (Spielberger’s State Anxiety Inventory -STAI) symptoms.
Results: Levels of C-reactive protein, zinc, haptoglobin, hematocrit and IgA/IgM responses to 9 TRYCATs
were also measured. No significant associations of the IgA/IgM responses to Gram-B with prenatal
depression and anxiety were observed. Increased IgA/IgM responses to Gram-B predict higher
levels of haptoglobin, hematocrit and TRYCATs, in particular quinolinic acid and the quinolinic acid /
kynurenic acid ratio. IgA responses to Gram-B were significantly lowered in pregnant women compared
to age-matched non-pregnant women, while IgM responses were significantly elevated in participants
with alcohol consumption. Physio-somatic symptoms at the end of term were significantly associated
with IgM responses to Klebsiella pneumonia. Postnatal anxiety was significantly predicted by
IgA responses to Pseudomonas aeruginosa.
Conclusions: Our findings suggest that pregnancy may protect against bacterial translocation, while
alcohol use may increase bacterial translocation. The results suggest that end of term mucosa-derived
immune responses to Gram-B contribute to immune activation, physio-somatic symptoms at the end of
term and postnatal anxiety.
Highlights: • Immune responses to Gram - Bacteria associate with physio-somatic symptoms in pregnancy.
• IgA responses to Pseudomonas aeruginosa predict anxiety symptoms after delivery.
• Pregnancy may have a protective effect against bacterial translocation.
• Alcohol use increases leaky gut and bacterial translocation.