Plasma cytokine and growth factor response to acute psychosocial stress in major depressive disorder.

BACKGROUND: Pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α are elevated in response to psychosocial stress; however, less is known about other inflammatory markers. METHODS: We explored response to the Trier Social Stress Test (TSST) of 16 cytokines and growth factors in patients with major depressive disorder (MDD, n = 12) vs. healthy volunteers (HV, n = 16). Outcomes were baseline and post-stress levels estimated by area under the curve (AUCi) and peak change over 3 timepoints. We also explored correlations between biomarkers and clinical characteristics. RESULTS: Baseline concentrations were higher in MDD for platelet-derived growth factor (PDGF)-AB/BB (p = 0.037, d = 0.70), granulocyte-macrophage colony-stimulating factor (GM-CSF, p = 0.033, d = 0.52), and IL-8 (p = 0.046, d = 0.74). After TSST, AUCi was higher in MDD for GM-CSF (p = 0.003, d = 1.21), IL-5 (p = 0.014, d = 1.62), and IL-27 (p = 0.041, d = 0.74). In MDD, depression severity correlated positively with soluble CD40L (sCD40L) for AUCi (Spearman's ρ = 0.76, p = 0.004) and with baseline vascular endothelial growth factor A (VEGFA, r = 0.85, p < 0.001), but negatively with baseline monokine induced by gamma interferon (MIG, aka CXCL9; r = -0.77, p = 0.003). CONCLUSIONS: Effect sizes were robust in this exploratory study, although interpretation of the results must be cautious, given small sample size and multiple comparisons. Differential study of stress-induced biomarkers may have important ramifications for MDD treatment.

Alkaptonuria Severity Score Index Revisited: Analysing the AKUSSI and Its Subcomponent Features.

BACKGROUND: Alkaptonuria (AKU) is a rare disorder with no licensed treatment; nitisinone may reduce symptoms and progression. The All Alkaptonuria Severity Score Index (AKUSSI) measures disease severity in clinical, joint and spine domains, with 57 subcomponent feature scores. Our primary aim was to assess tools for validating scores such as the AKUSSI by detecting relationships between features both before and during nitisinone treatment. METHODS: AKUSSI measurements from nitisinone-treated patients visiting the National AKU Centre between 01-Jun-2012 and 31-May-2016 were analysed pre-treatment, at first treatment and annually to Year 3 post-treatment. Principal component analysis (PCA) and redundancy analysis assessed whether any AKUSSI features contributed little information to the overall score. RESULTS: 65 AKU patients were included: 17 with a pre-treatment AKUSSI measurement (10 later received nitisinone) and 48 with a first measurement at their first treatment visit. In PCA, the first four principal components (PC1-PC4) explained ≥50% of AKUSSI variance at all visits (54.1-87.3%). Some features regularly dominated their domain's PC1: ears, aortic sclerosis, and nasal/temporal eye scores (clinical), pain-related scores (joint) and cervical, lumbar and thoracic spine scores (spine). Only the right-hand/wrist score was consistently redundant. Right eye (nasal) and left ear scores were redundant pre-treatment, potentially correlating with other dominant clinical PC1 features. CONCLUSIONS: PCA and redundancy analysis supported the AKUSSI as a robust AKU disease severity measure, although some AKUSSI features could be removed for simplicity. For small patient populations and rare diseases, PCA and redundancy analysis together can aid validation of disease severity metrics.