Table 3 Included articles and their main Findings
From: Effects of inflammation on the kynurenine pathway in schizophrenia — a systematic review
Author, year | Sample size | Main findings | |
|---|---|---|---|
Controls | Patients | ||
A. Immunoglobulins | |||
Kanchanatawan et al. 2017 [40] | 40 | 84 clinically stable Sz outpatients | - Physiosomatic symptoms were significantly associated with IgA/IgM responses to TRYCATs, including increased IgA responses to 3 HK, picolinic acid, and xanthurenic acid and lowered IgA responses to QUIN acid and AA |
Kanchanatawan et al. 2018a [41] | 40 | 80 Sz outpatients, 40 deficit, and 40 non-deficit patients | - Deficit schizophrenia increased TRYCAT vs. controls and non-deficit - Both schizophrenia subgroups showed increased IgA responses to 3-OH-kynurenine - Negative symptoms positively correlated with increased IgA responses directed against picolinic acid and inversely with anthranilic acid without significant associations between positive ones and IgA responses to TRYCATs |
Kanchanatawan et al. 2018b [42] | |||
Bechter et al. 2010 [43] | 4100 | Inpatient Sz = 39, inpatient Af = 24 | - Intrathecal immune response in 9 patients (4 with schizophrenia) - Blood-brain barrier dysfunction in 18 patients (9 of them with schizophrenia) - Neopterin concentrations increased in 14 patients (8 of them with schizophrenia) - Absence of any significant changes in tryptophan nor kynurenine metabolites |
B. Interleukins | |||
Szymona et al. 2017 [44] | 45 | 51 Sz inpatients | - KYNA/3-HK ratio and IL-4 levels decreased - Negative correlation between IFN-α and 3-HK level - A positive correlation between KYNA and IFN-α |
Barry et al. 2009 [45] | 36 | 34 outpatients | - Significant higher kynurenine/tryptophan ratio in patients without significant correlation with IFN-γ values. |
Kim et al. 2009 [46] | 174 | 71 medication-free assessed on admission and discharge after 6 weeks | At admission: - Th1-specific IFN-γ and TNF-α, and Th2-related IL-6 were higher - Tryptophan was significantly lower - Th1-related IL-2 and Th2-specific IL-4 were significantly lower - Th1/Th2 ratio ([IFN-γ]/[IL-4]) correlated positively with the tryptophan breakdown index ([kynurenine]/plasma [tryptophan]) After six weeks of treatment: - A significant reduction of plasma IL-6 and TNF- α - Both mean tryptophan and kynurenine levels were significantly increased |
Schwieler et al. 2015 [47] | 37 | 23 Sz | - Correlation between IL-6 and KYNA-production |
Kegel et al. 2017 [48] | Outpatient (MZ) | Outpatient (DZ) | - Correlation between IL-8 and QUIN - Correlation between TNF-α and QUIN |
12 (2 single twins) | 11 (one single twin) | ||
C. C-reactive protein | |||
Wurfel et al. 2017 [49] | 92 | Inpatient MDD (N = 35), BD (N = 53), SzA (N = 40), acutely ill Sz (n = 21) | Sz patients versus MDD, BD and SZA subgroups showed no significant difference in KYNA/QUIN and compared to healthy controls |