Predictive effect of lipopolysaccharide-stimulated inflammatory cytokines on symptoms of generalized anxiety disorder

Background: Generalized anxiety disorder (GAD) is a relatively common mental disorder. Recently, inflammation, an important factor for the development of depression, has attracted increasing attention. Several studies have shown that inflammatory cytokines can affect the pathophysiological processes of several nervous system diseases. We hypothesized that there is a correlation between the levels of lipopolysaccharide (LPS)-stimulated inflammatory cytokines and the clinical symptoms of GAD.

Aim: To investigate the predictive effect of LPS-stimulated inflammatory cytokines on symptoms of GAD.

Methods: This was a cross-sectional study in which 89 patients with GAD diagnosed at The First Hospital of Hebei Medical University from January 2022 to December 2022 and 70 individuals without anxiety and depression (controls) during the same period were included. Fasting venous blood was collected from all the subjects in heparin tubes, and another 3 ml of blood was supplemented with LPS (10 ng/ml). The plasma levels of 12 cytokines [Interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-17A, IL-12p70, and IFN-α] were detected.

Results: Post-LPS stimulation, the levels of IL-1β, IL-6, IL-8, IL-10, and TNF-α in both the control and GAD groups were significantly elevated above those in the nonstimulated groups, with IL-6 and IL-8 showing marked increases. Increases in IL-8 and TNF-α were statistically significant in the GAD group (P < 0.05). IL-1β, IL-6, IL-8, IL-10, and TNF-α were found to be significantly correlated with Hamilton Anxiety Rating Scale (HAMA) scores (P < 0.05). A negative correlation was observed between IL-10 levels and HAMA scores. Further analysis revealed that TNF-α was associated with mental anxiety, whereas IL-1β, IL-8, and IL-10 were associated with physical anxiety symptoms, with IL-10 showing a negative correlation with physical anxiety. IL-6 was associated with both mental and physical aspects of anxiety.

Conclusion: The physical symptoms of GAD are related to inflammatory factors. IL-1β, IL-8, IL-10, and TNF-a can be used as predictors of physical or mental anxiety in patients with GAD.