Elevation of plasma neutrophil gelatinase-associated lipocalin (NGAL) levels in schizophrenia patients.

Background: Psychiatric diseases are usually accompanied by immune dysregulation and activation of the inflammatory response system. However, the characteristics of immunoinflammatory markers in psychiatric diseases are not well defined.

Methods: Seventy-three patients with psychiatric diseases were divided into four groups, including a schizophrenia group, an anxiety disorder group, a unipolar depression group, and a bipolar disorder group, according to the ICD-10 and DSM-IV codes. Neutrophil gelatinase-associated lipocalin (NGAL) and associated classical immunoinflammatory markers including C-reactive protein (CRP), Th1/Th2 cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ), total leukocyte count (TLC), and neutrophilic granulocyte percentage (NEU%) were analysed; patients with physical diseases were excluded to avoid confounders. Fifteen healthy, age- and gender-matched individuals served as controls.

Results: Compared with the corresponding values in the control group, the level of CRP in each psychiatric disease group, the levels of IFN-γ and NGAL in the schizophrenia group, and the NEU% in the depression group were significantly elevated (P < 0.05). Compared with the levels in the schizophrenia group, the levels of CRP in the bipolar disorder and depression groups, the level of IFN-γ in the bipolar disorder group, and the levels of NGAL in the anxiety disorder and depression groups were significantly decreased (P < 0.05). Compared with the depression group, the bipolar disorder group showed significant elevation the NGAL level.

Limitation: The sample size was relatively small.

Conclusions: Immunoinflammatory markers were elevated in patients with psychiatric diseases, especially schizophrenia. We are the first to report that the level of NGAL is significantly increased in schizophrenia patients.