C-reactive protein is not a biomarker of depression severity in drug-naïve obese patients with metabolic syndrome

Background Metabolic syndrome (MetS) is highly prevalent among adults and is frequently accompanied by depressive symptoms. While high-sensitivity C-reactive protein (hsCRP) has been proposed as a potential indicator of depression, existing evidence remains inconclusive. Objective This study aimed to determine whether increased serum hsCRP or other immune-metabolic biomarkers are associated with depressive symptoms in drug-naïve individuals with obesity and MetS. Methods A total of 88 drug-naïve patients with obesity and MetS but without coronary-artery disease were enrolled and serum levels of neuro-immune and metabolic biomarkers were assessed. Results In MetS, the severity of depression, as assessed using the von Zerssen Depression Rating (VZDR) scale was significantly associated with interleukin (IL)-6, leukocyte numbers, triglyceride x glucose (Tyg) index, low-density lipoprotein cholesterol, Apolipoprotein B (all positively) and mean platelet volume (MPV), visfatin and adiponectin (all negatively). There were no significant associations between hsCRP and severity of depression. In MetS patients, hsCRP is strongly associated with increased leukocyte numbers, alkaline phosphatase, γ-glutamyl transferase, uric acid, platelet numbers and MPV, thereby shaping a distinct subtype of MetS, which is not related to depression. Conclusions Our findings indicate that depressive symptoms in MetS patients are associated with immune–metabolic biomarkers indicating immune activation, atherogenicity and insulin resistance, but not with hsCRP. The reason is that hsCRP in MetS is a biomarker of a specific MetS subtype that is characterized by megakaryopoiesis, hepatocyte activation, and uric acid production, which were not associated with depression.