Leaky gut biomarkers in depression and suicidal behavior

Abstract

Objective

Inflammation is associated with major depressive disorder ( MDD) and suicidal behavior. According to the ‘leaky gut hypothesis’, increased intestinal permeability may contribute to this relationship via bacterial translocation across enterocytes. We measured plasma levels of gut permeability markers, in patients with a recent suicide attempt ( rSA), MDD subjects with no history of a suicide attempt (ns MDD), and healthy controls ( HC), and related these markers to symptom severity and inflammation.

Method

We enrolled rSA ( n = 54), ns MDD ( n = 13), and HC ( n = 17). Zonulin, intestinal fatty acid binding protein (I‐ FABP), soluble CD14, and interleukin‐6 ( IL‐6) were quantified in plasma. Montgomery–Åsberg Depression Rating Scale ( MADRS) and Suicide Assessment Scale ( SUAS) were used for symptom assessments.

Results

The rSA group displayed higher I‐ FABP and lower zonulin levels compared with both the ns MDD and the HC groups (all P < 0.001). IL‐6 correlated positively with I‐ FABP ( r = 0.24, P < 0.05) and negatively with zonulin ( r = −0.25, P < 0.05). In all subjects, I‐ FABP levels correlated positively with MADRS ( r = 0.25, P < 0.05) and SUAS scores ( r = 0.38, P < 0.001), and the latter correlation was significant also in the ns MDD group ( r = 0.60, P < 0.05).

Conclusion

The ‘leaky gut hypothesis’ may improve our understanding of the link between inflammation and suicidal behavior. These findings should be considered preliminary until replicated in larger cohorts.