Immunological investigations of the cerebrospinal fluid in patients with recent onset psychotic disorders: A study protocol

Levels of cytokines in the cerebrospinal fluid of patients with psychotic disorders compared to individually matched healthy controls

BACKGROUND

Increased peripheral cytokine levels have been observed in patients with psychotic disorders; however, large high-quality studies with individually matched healthy controls have been lacking regarding cytokines in cerebrospinal fluid (CSF) of individuals with psychotic disorders.

METHODS

Patients diagnosed with a non-organic, non-affective psychotic disorder (ICD-10: F20/22-29) within a year prior to inclusion and individually age- and sex-matched healthy controls were included by identical in- and exclusion criteria's except for the psychiatric diagnoses. All participants were aged 18-50 years and individuals with neurological or immunological disorders were excluded. CSF cytokines were analyzed with MesoScale V-PLEX neuroinflammation panel. Co-primary outcomes were CSF interleukin-6 (IL-6) and IL-8.

RESULTS

We included 104 patients and 104 healthy controls, matching on age, sex and BMI. No significant differences were found for the primary outcomes IL-6 (relative mean difference (MD): 0.97, 95 %CI: 0.84-1.11, p = 0.637) or IL-8 (MD: 1.01, 95 %CI: 0.93-1.09, p = 0.895). Secondary analyses found patients to have higher IL-4 (MD: 1.30, 95 %CI: 1.04-1.61, p = 0.018), a trend towards higher IFN-γ (MD: 1.26, 95 %CI: 0.99-1.59, p = 0.056), and lower IL-16 (MD: 0.83, 95 %CI: 0.74-0.94, p = 0.004) than healthy controls, though not significant after correction for multiple testing. IL-8 and IL-16 were found positively associated with CSF white blood cells and CSF/serum albumin ratio. The study was limited by 77.9 % of the patients being on antipsychotic treatment at time of intervention, and that levels of nine of the 26 cytokines were below lower limit of detection (LLOD) in >50 % of samples; however, for the primary outcomes IL-6 and IL-8 more than 99.5 % of the samples were above LLOD and for IL-8 all samples exceeded the lower limit of quantification (LLOQ).

CONCLUSIONS

We found no evidence of increased IL-6 and IL-8 in patients with recent-onset psychotic disorders in contrary to previous findings in meta-analyses of CSF cytokines. Secondary analyses found indication of higher IL-4, decreased IL-16, and borderline increased IFN-γ in patients, neither of which have previously been reported on in CSF analyses of individuals with psychotic disorders.

Antineuronal antibodies in cerebrospinal fluid and serum of 104 patients with psychotic disorders compared to 104 individually matched healthy controls

BACKGROUND

Antineuronal antibodies can cause psychotic symptoms, particularly NMDAR antibodies; however, studies on the prevalence of antineuronal antibodies in cerebrospinal fluid (CSF) and serum of patients with psychotic disorders compared to matched healthy controls are sparse.

METHODS

We included 104 patients with a first-time diagnosis of a psychotic disorder within one year prior to inclusion (50 % outpatients) and 104 individually matched healthy controls, all without any known immunological conditions. CSF and serum were tested for IgG antibodies (Abs) against NMDAR NR1-subunit, GAD65, LGI1, CASPR2, AMPAR1, AMPAR2 and GABAb-receptor B1/B2 using commercial fixed cell-based assays (CBAs) (Euroimmun). Positive samples were retested with CBA twice, and tested with tissue-based assays (TBA). Primary outcomes were the presence of any of the seven anti-neuronal antibodies in CSF or serum. Secondarily, we analyzed the prevalence of each autoantibody.

RESULTS

No antineuronal IgG antibodies were consistently found in any CSF sample and NMDAR-antibodies were not consistently present in any of the 208 participants, neither in CSF nor serum. CASPR2-Abs were consistently found in the serum of one patient and one control, and one healthy control, without diabetes, was seropositive for GAD65-Abs. CASPR2 borderline seropositivity was additionally found in one patient and two controls. All samples positive on CBA were negative on TBA.

CONCLUSIONS

We found no significant differences between patients and controls. Antineuronal IgG antibodies are very rare when screening a broad group of individuals with recent-onset psychotic disorders without other indications of autoimmune encephalitis. Thus, much larger studies are needed to conclude on potential contrasts in prevalence compared to healthy controls.

Cerebrospinal Fluid and Blood Biomarkers of Neuroinflammation and Blood-Brain Barrier in Psychotic Disorders and Individually Matched Healthy Controls

BACKGROUND AND HYPOTHESIS

Neuroinflammation and blood-brain barrier (BBB) dysfunction have been observed in patients with psychotic disorders. However, previous studies have mainly focused on selected patients and broad screenings of cerebrospinal fluid (CSF) of patients with recent onset psychosis compared to healthy controls are lacking.

STUDY DESIGN

We included 104 patients with recent onset psychotic disorder and 104 individually matched healthy controls. CSF and blood were analyzed for readily available markers assessing neuroinflammation and BBB dysfunction. Primary outcomes were CSF white blood cell count (WBC), total protein, IgG Index, and CSF/serum albumin ratio. Secondary outcomes included additional markers of inflammation and BBB, and analyses of association with clinical variables.

STUDY RESULTS

CSF/serum albumin ratio (Relative Mean Difference (MD): 1.11; 95%CI: 1.00-1.23; P = .044) and CSF/serum IgG ratio (MD: 1.17; 95%CI: 1.01-1.36; P = .036) was increased in patients compared to controls. A higher number of patients than controls had CSF WBC >3 cells/µl (seven vs. one, OR: 7.73, 95%CI: 1.33-146.49, P = .020), while WBC>5 cells/µl was found in two patients (1.9%) and no controls. Inpatients had higher serum WBC and neutrophil/lymphocyte ratio (all p-values for effect heterogeneity < .011). Mean CSF WBC (MD: 1.10; 95%CI: 0.97-1.26), protein (MD: 1.06; 95%CI: 0.98-1.15) and IgG index (MD: 1.05; 95%CI: 0.96-1.15) were not significantly elevated.

CONCLUSIONS

When comparing a broad group of patients with psychotic disorders with healthy controls, patients had increased BBB permeability, more patients had high CSF WBC levels, and inpatients had increased peripheral inflammation, consistent with the hypothesis of a subgroup of patients with increased activation of the immune system.

Neuroimmunological investigations of cerebrospinal fluid in patients with recent onset depression - a study protocol

BACKGROUND

A proinflammatory response has been suggested to be involved in the pathophysiology of depression in a subgroup of patients. However, comprehensive largescale studies on neuroimmunological investigations of the cerebrospinal fluid (CSF) are lacking and no largescale longitudinal CSF studies comparing patients with depression to healthy controls currently exist.

METHODS

A longitudinal case-control study including at least 100 patients with first time depression (ICD-10: F32) within the past year with ongoing symptoms and at least 100 sex and age matched healthy controls with collection of CSF, blood, and fecal samples. All individuals will be evaluated by neurological examination including neurological soft signs, interviewed for psychopathology assessment and have symptomatology evaluated by relevant rating scales. Level of functioning and quality of life will be evaluated by a panel of interview questions and rating scales, and cognitive function assessed by a relevant test battery. In addition, a large number of potential confounders will be registered (BMI, smoking status, current medication etc.). Primary outcomes: CSF white cell count, CSF/serum albumin ratio, CSF total protein levels, IgG index, CSF levels of IL-6 and IL-8, and the prevalence of any CNS-reactive autoantibody in CSF and/or blood.

SECONDARY OUTCOMES

exploratory analyses of a wide range of neuroimmunological markers and specific autoantibodies. Power calculations are computed for all primary outcomes based on previous CSF studies including patients with depression and healthy controls.

DISCUSSION

This study will represent the hitherto largest investigation of CSF in patients with recent onset depression compared to healthy controls. We expect to elucidate neuroimmunological alterations in individuals with depression and characterize an immunological profile paving the way for the development of effective treatments based on biomarkers.

TRIAL REGISTRATION

The study is approved by The Regional Committee on Health Research Ethics (Capital Region, j.no: H-16030985) and The Danish Data Protection Agency (j.no: RHP-2016-020, I-Suite no.: 04945).