Peripheral interleukin-2 level is associated with negative symptoms and cognitive performance in schizophrenia

Abstract

Although several studies have pointed to a possible role of interleukin 2 (IL-2) in schizophrenia (SZ), association between IL-2 and the different groups of symptoms has not been explored. The objective of this study was to investigate a possible correlation of peripheral IL-2 levels with symptoms and cognitive performance in patients with SZ. In addition, we compared the plasma levels of IL-2 between patients with SZ and healthy controls. Twenty-nine chronically medicated outpatients with SZ according to DSM-IV were compared with twenty-six healthy controls. The patients were evaluated with the Positive and Negative Syndrome Scale (PANSS), the Calgary Depression Scale for Schizophrenia (CDSS), the Clinical Global Impression (CGI) and the Global Assessment of Functioning (GAF). All the participants had blood collected into EDTA tubes by venipuncture between 9:00 and 10:00AM. Plasma concentrations of IL-2 were determined by cytometric bead array. A computerized neuropsychological battery assessed verbal learning, verbal fluency, working memory, set shifting, executive function, inhibition and intelligence. Patients with SZ had lower levels of IL-2 than healthy controls (p<0.001). In the SZ group, IL-2 levels were positively correlated with scores in the digit span test (rho=0.416, P=0.025) and intelligence (rho=0.464, P=0.011). We also found a negative correlation between IL-2 and total score in the negative subscale of PANSS (rho=-0.447, p=0.015). Our findings suggest that IL-2 may be involved in the mechanisms related to cognitive deterioration and negative symptomatology in schizophrenia.

Association of inflammatory biomarkers with depressive symptoms and cognitive decline in a community-dwelling healthy older sample: A 3-year follow-up study

“…IL-2 gene deletion has been shown to alter the neuroimmunological status of the mouse hippocampus through dysregulation of cytokines produced by central nervous system (CNS) cells, which is associated with increased hippocampal neurogenesis in male mice (Beck et al, 2005). In patients with schizophrenia, IL-2 levels were reported to be positively correlated with digit span and intelligence, and to be negatively correlated with total score on the negative subscale of the Positive and Negative Syndrome Scale (PANSS) (Asevedo et al, 2014). To our knowledge, ours is the first study to find sIL-2R to be associated with current cognitive function in men.…”

Biomarkers in schizophrenia: A focus on blood based diagnostics and theranostics

“…There is evidence to suggest that the levels of some inflammatory molecules in blood are correlated with symptom severity in people with Sz [10,33,48,60,63,67] . For example, plasma levels of IL2 in people with Sz were reported to be positively correlated with the scores in cognitive tests of digit span test (r 2 = 0.17) and intelligence (r 2 = 0.19), and negatively correlated with the presence of negative symptoms (r 2 = 0.2 [67] ), levels of IL1β and TNFα mRNA in PBMC were positively correlated (r 2 = 0.17) with scores on the general psychopathology factor of the PANSS [48] and changes in serum IL-10 levels were significantly correlated with improvements in symptoms [i.e., negative, general psychopathology and total score (r 2 = 0.10.2)] among people with first-onset Sz [60] .…”

“…For example, plasma levels of IL2 in people with Sz were reported to be positively correlated with the scores in cognitive tests of digit span test (r 2 = 0.17) and intelligence (r 2 = 0.19), and negatively correlated with the presence of negative symptoms (r 2 = 0.2 [67] ), levels of IL1β and TNFα mRNA in PBMC were positively correlated (r 2 = 0.17) with scores on the general psychopathology factor of the PANSS [48] and changes in serum IL-10 levels were significantly correlated with improvements in symptoms [i.e., negative, general psychopathology and total score (r 2 = 0.10.2)] among people with first-onset Sz [60] . Levels of the chemokine, CCL11, were not only higher in people with Sz but were negatively correlated with performance on the working memory test (r 2 = 0.16) and positively corre lated with a cognitive flexibility task (r 2 = 0.26 [33] ).…”

“…In summary, people with Sz demonstrate a distinct profile of immune peptides, aberrant immunological responses, and changes of immune cell counts. For example, higher plasma levels of IL2 appears to be a promising Sz specific biomarker [47] which may reflect the clinical symptom as well as cognitive function [67] particularly since the levels decrease following treat ment with antipsychotic drugs [58,59] . Some of these changes in the immune system markers correlate with treatment responses and symptom profiles, suggesting they may be suitable theranostic markers.…”

Envolvimento Da Flora Intestinal Na Modulação De Doenças Psiquiátricas

“…Muitos pacientes esquizofrênicos também apresentam distúrbios gastrointestinais, evidenciando um possível envolvimento da composição da microbiota intestinal na patofisiologia da doença (146)(147)(148). Além disso, vários estudos têm demonstrado que o sistema imunológico está desregulado em pacientes esquizofrênicos, além de haver uma correlação entre o risco de desenvolver esquizofrenia e genes relacionados com o sistema imunológico (149)(150)(151)(152)(153), sugerindo uma possível modulação da flora intestinal. Nestes pacientes, citocinas pró-inflamatórias (ex.…”