Patients with schizophrenia show raised serum levels of the pro-inflammatory chemokine CCL2: association with the metabolic syndrome in patients?

Patients with schizophrenia show raised serum levels of the pro-inflammatory chemokine CCL2: Association with the metabolic syndrome in patients? Dear Editors, Serum levels of the pro-inflammatory cytokines IL-1β, IL-6 and TNF-α are raised in schizophrenia (Schuld et al., 2004). However, apart from these pro-inflammatory cyto-kines, chemokines play an important role in modulating brain function (Adler and Rogers, 2005). The system of chemokines and their receptors has been described as a major regulating system of the brain and the receptor for CCL2, CCR2, is expressed in the brain by astrocytes, microglia and neurons (Bajetto et al., 2002). CCL2 (Chemokine (C–C motif) ligand 2) is an important pro-inflammatory chemokine, playing a key role in the recruitment of monocytes to inflammatory foci (Kamei et al., 2006; Simeoni et al., 2004). Interestingly, a genotypic association was found between the A-2518G polymorph-ism of the CCL2 gene and resistance to anti-psychotic medication (Mundo et al., 2005) and a predominance of negative symptoms over positive symptoms (Pae et al., 2004). The A-2518G polymorphism affects the production of CCL2 (Mundo et al., 2005). However, it is unclear if CCL2 serum levels are changed in patients with schizo-phrenia. One study reported a normal level of CCL2 in the serum of a small group of institutionalized male patients (Teixeira et al., 2007), while another study reported an elevation of CCL2 in the cerebrospinal fluid of a small group of patients with psychosis serving as controls for a study on neuro-psychiatric lupus (Iikuni et al., 2006). Here we present a study on the CCL2 levels in the serum of 145 patients with chronic schizophrenia. Patients participated in a study on the prevalence of abnormalities in glucose metabolism in patients with schizophrenia or schizo-affective disorder treated with anti-psychotics; the demographic data, study design, hyperglycemia measurements , diabetes and metabolic syndrome definition and outcomes have been reported in detail before (Cohen et al., Fig. 1. a: CCL2 levels are significantly (p b 0.026) higher in patients with schizophrenia with the metabolic syndrome (diamond: n = 52, median 221.91 pg/ml, range up to 955.60 pg/ml) compared to patients without the metabolic syndrome (circle: n = 93, median 179.08 pg/ml, range up to 781.80 pg/ml), while the CCL2 levels of the latter group are significantly higher (p b 0.001) compared to the levels of healthy controls (quadrangle: n = 105, median 141.41 pg/ml, range up to 310.35 pg/ml). CCL2 levels are also significantly (p b …