Deficiencies of the T and natural killer cell system in major depressive disorder: T regulatory cell defects are associated with inflammatory monocyte activation.

BACKGROUND: In a previous study, we found an up-regulated inflammatory monocyte gene expression profile in major depressive disorder (MDD) patients aged ⩾ 28 years and a down-regulated inflammatory gene expression profile in MDD patients aged<28 years. In the same sample of patients, we aimed to investigate immune dysregulation in the lymphocyte arm of the immune system, particularly in the context of the described monocyte (de-)activation states. METHODS: From deep frozen leukocytes, circulating percentages of monocytes, lymphocytes, B, T, and natural killer (NK) cells, and various functional subsets of T and T helper (Th) cells (Th1, Th2, Th17, and natural T regulatory cells) were measured in N=50 MDD patients and N=58 age- and gender-matched healthy controls (HC). In addition, serum levels of interleukin (IL)-6, sCD25, IL-7, IL-3, SCF, IGF-BP2, and EGF were evaluated. RESULTS: MDD patients were in general characterized by an impaired maturation of Th2 cells, Th17 cells, and NK cells and by decreased serum levels of IL-7 and sCD25. MDD patients aged ⩾ 28 years additionally exhibited decreased percentages of CD4(+)CD25(high)FoxP3(+) T regulatory cells, next to signs of the above described partial T cell defects. Natural T regulatory cells were inversely associated with the pro-inflammatory state of the monocytes (r=-.311; p=.034) that characterized this patient subgroup. CONCLUSIONS: Deficiencies of the NK and T (regulatory) cell system and inflammatory monocyte immune activation co-occur as partly interrelated phenomena within the same MDD patients.

Antisense oligonucleotide therapy corrects splicing in the common Stargardt disease type 1-causing variant ABCA4 c.5461-10T>C.

Stargardt disease type 1 (STGD1) is the most common hereditary form of maculopathy and remains untreatable. STGD1 is caused by biallelic variants in the ABCA4 gene, which encodes the ATP-binding cassette (type 4) protein (ABCA4) that clears toxic byproducts of the visual cycle. The c.5461-10T>C p.[Thr1821Aspfs∗6,Thr1821Valfs∗13] variant is the most common severe disease-associated variant, and leads to exon skipping and out-of-frame ABCA4 transcripts that prevent translation of functional ABCA4 protein. Homozygous individuals typically display early onset STGD1 and are legally blind by early adulthood. Here, we applied antisense oligonucleotides (AONs) to promote exon inclusion and restore wild-type RNA splicing of ABCA4 c.5461-10T>C. The effect of AONs was first investigated in vitro using an ABCA4 midigene model. Subsequently, the best performing AONs were administered to homozygous c.5461-10T>C 3D human retinal organoids. Isoform-specific digital polymerase chain reaction revealed a significant increase in correctly spliced transcripts after treatment with the lead AON, QR-1011, up to 53% correct transcripts at a 3 µM dose. Furthermore, western blot and immunohistochemistry analyses identified restoration of ABCA4 protein after treatment. Collectively, we identified QR-1011 as a potent splice-correcting AON and a possible therapeutic intervention for patients harboring the severe ABCA4 c.5461-10T>C variant.

An activated set point of T-cell and monocyte inflammatory networks in recent-onset schizophrenia patients involves both pro- and anti-inflammatory forces.

We recently described a pro-inflammatory gene expression signature in the monocytes of 60% of patients with recent-onset schizophrenia (SCZ). Here we investigated whether the T-cell system is also in a pro-inflammatory state. A detailed fluorescence-activated cell sorting (FACS) analysis, e.g. of CD3+CD25+ T cells, IFN-γ+, IL-4+, IL-17A+ (CD4+) lymphocytes and CD4+CD25highFoxP3+ regulatory T cells, was performed on peripheral blood of 26 patients with recent-onset SCZ (in 19 of whom the inflammatory gene expression signature of the monocyte had been determined) and in age-/gender-matched healthy controls. Various relevant T-cell cytokines, e.g. sCD25, IFN-γ, IL-17A and IL-4, were measured in serum by a multiplex assay. We detected: (a) not only higher percentages of pro-inflammatory-prone monocytes, activated CD3+CD25+ T cells and pro-inflammatory Th17 cells in patients, but also higher percentages of anti-inflammatory CD4+CD25highFoxP3+ regulatory T cells and IL-4+ lymphocytes; (b) that this activated T-cell set point was reflected in significantly raised serum levels of sCD25; (c) that the up-regulation of IL-4+-containing lymphocytes was predominantly found in patients characterized by a monocyte pro-inflammatory set point; and (d) that regulatory T-cell and Th17-cell numbers were higher in patients irrespective of the pro-inflammatory state of the monocytes. Our data do not support the concept that the T-cell system is in a simple pro-inflammatory state in recent-onset SCZ, but do show that the monocyte and T-cell networks are activated and involve both pro- and anti-inflammatory forces. This suggests control within an activated inflammatory system.

The activation of monocyte and T cell networks in patients with bipolar disorder.

OBJECTIVES: We recently described a monocyte pro-inflammatory state in patients with bipolar disorder (BD). We hypothesized that the CD4(+)T cell system is also activated and determined percentages of Th1, Th2, Th17 and CD4(+)CD25(high)FoxP3(+) regulatory T cells. METHODS: We carried out a detailed FACS analysis to determine the various T cell subsets and used frozen stored peripheral blood mononuclear cells (PBMC) of 38 BD patients (of whom we previously had tested monocytes for pro-inflammatory gene expression (Drexhage et al., 2010b; Padmos et al., 2008)) and of 22 age/gender matched healthy controls (HC). In addition the cytokines CCL2, IL-1ß, IL-6, TNF-α, PTX3, IL-10, IFN-γ, IL-17A, IL-4, IL-5 and IL-22 were measured in serum. RESULTS: (a) Serum sCD25 levels and percentages of anti-inflammatory CD4(+)CD25(high)FoxP3+ regulatory T cells were higher, the latter in BD patients <40 years of age. Percentages of Th1, Th2 and Th17 cells were normal. (b) Of the pro-inflammatory monocyte cytokines CCL2 and PTX3 were raised in serum. (c) The monocyte pro-inflammatory state and the raised percentages of CD4(+)CD25(high)FoxP3(+) regulatory T cells occurred independently from each other. (d) In BD patients positive for thyroid autoimmune disease a significantly reduced percentage of CD4(+)CD25(high)FoxP3(+) regulatory T cells was found as compared to BD patients without AITD. CONCLUSION: Our data show an enhancement of pro-inflammatory monocyte and anti-inflammatory T cell forces in BD patients. A lack of anti-inflammatory T cell forces co-occurred with AITD in BD patients.

Markers of neuroinflammation influence measures of cortical thickness in bipolar depression.

We tested if peripheral levels of cytokines and chemokines associate to grey matter volumes, cortical thickness and fMRI neural responses to a moral valence decision task in bipolar patients. ICAM1 and CCL4 negatively correlated with cortical thickness in Inferior Temporal Gyrus, and sCD25 in Parahippocampal Gyrus. TNF-α, Interleukine-8, and CCL2 correlated positively with cortical thickness in the Anterior Cingulate Cortex, and with lower BOLD responses to negative stimuli. Markers of immune activation are associated with measures of brain structural and functional integrity in bipolar depression.

Higher Baseline Proinflammatory Cytokines Mark Poor Antidepressant Response in Bipolar Disorder.

BACKGROUND: The clinical relevance of raised levels of circulating cytokines in bipolar disorder is still unclear. Cytokines influence neurotransmitters, neuroplasticity, and white matter integrity. An inconsistent literature suggests that higher cytokine levels could hamper antidepressant response. Total sleep deprivation (TSD) and light therapy (LT) prompt a rapid antidepressant response and can provide a model treatment to study predictors of response. METHODS: We studied at baseline 15 immune-regulating compounds in 37 consecutively admitted inpatients with a major depressive episode in the course of bipolar disorder (DSM-5 criteria) and in 24 controls. Thirty-one patients (84%) had a lifetime history of drug resistance. Patients were administered 3 TSD + LT cycles in 1 week (study period: 2010-2012). Data were analyzed with age- and false-discovery-rate-corrected analysis of variance and were tested as predictors in a regressive model. RESULTS: Twenty-three patients (62%) responded to treatment (Inventory of Depressive Symptomatology IDS-C score < 12). Five highly intercorrelated compounds (IL-8, MCP-1, IFN-γ, IL-6, TNF-α) showed higher levels in nonresponder patients as compared to responders, corrected for multiple comparisons (respectively F = 6.138, PFDR = .0134; F = 6.197, PFDR = .0134; F = 4.785, PFDR = .0255; F = 3.782, PFDR = .0441; F = 3.764, PFDR = .0441). A principal component analysis identified a single component that explained 84% of variance of these cytokines (Q² = 0.15), and a high factor score significantly predicted worse response (b = -0.692; W = 4.34, P = .037). A higher body mass index correlated with higher cytokines (r = 0.430, P = .010), indirectly hampering response (b = -0.0192, P = .013). CONCLUSIONS: Proinflammatory compounds reflecting an M1-like proinflammatory state of monocytes/macrophages are associated with a poor response to antidepressant TSD + LT treatment in bipolar depression.

Stem Cell Factor (SCF) is a putative biomarker of antidepressant response.

Growth factors involved in neurogenesis and neuroplasticity could play a role in biological processes that drive depression recovery. Combined total sleep deprivation and morning light therapy (TSD + LT) can acutely reverse depressive symptoms, thus allowing to investigate the neurobiological correlates of antidepressant response. We tested if changes on plasma levels of Brain Derived Neurotrophic Factor (BDNF), S100 calcium binding protein B (S100-B), Stem Cell Factor (SCF), Insulin-like Growth Factor-Binding Protein 2 (IGFBP-2), Epidermal Growth Factor (EGF), Platelet-Derived Growth Factor-BB (PDGF-BB), and Vascular Endothelial Growth Factor (VEGF) are associated with response to TSD + LT in 26 inpatients affected by a major depressive episode in the course of bipolar disorder. Regional grey matter (GM) volumes were assessed at baseline, and BOLD fMRI neural responses to a moral valence decision task were recorded before and after treatment. 61.5 % of patients responded to treatment. SCF plasma levels increased significantly more in responders, and correlated with GM volumes in frontal and parietal cortical areas. The pattern of change of SCF also associated with both GM volumes and changes of BOLD fMRI neural responses in the anterior cingulate and medial prefrontal cortex. SCF is both a hematopoietic growth factor and a neurotrophic factor, involved in neuron-neuron and neuron-(micro) glia interactions, fostering neuronal growth and an anti-inflammatory milieu. We correlated SCF levels with antidepressant response and with functional and structural MRI measures in cortical areas that are involved in the cognitive generation and control of affect. SCF may be a candidate growth factor that contributes to neurotrophic and immune effects that are involved in the process of remission/recovery from depression.

Inflammatory cytokines influence measures of white matter integrity in Bipolar Disorder.

BACKGROUND: Bipolar Disorder (BD) is associated with elevated biomarkers of cell-mediated immune activation and inflammation and with signs of widespread disruption of white matter (WM) integrity in adult life. Consistent findings in animal models link WM damage in inflammatory diseases of the brain and serum levels of cytokines. METHODS: With an exploratory approach, we tested the effects of 22 serum analytes, including pro- and anti-inflammatory cytokines and neurotrophic/hematopoietic factors, on DTI measures of WM microstructure in a sample of 31 patients with a major depressive episode in course of BD. We used whole brain tract-based spatial statistics in the WM skeleton with threshold-free cluster enhancement of DTI measures of WM microstructure: axial (AD), radial (RD), and mean diffusivity (MD), and fractional anisotropy (FA). RESULTS: The inflammation-related cytokines TNF-α, IL-8, IFN-γ and IL-10, and the growth factors IGFBP2 and PDGF-BB, shared the same significant associations with lower FA, and higher MD and RD, in large overlapping networks of WM fibers mostly located in the anterior part of the brain and including corpus callosum, cingulum, superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculi, uncinate, forceps, corona radiata, thalamic radiation, internal capsule. CONCLUSIONS: Higher RD is thought to signify increased space between fibers, suggesting demyelination or dysmyelination. The pattern of higher RD and MD with lower FA suggests that inflammation-related cytokine and growth factor levels inversely associate with integrity of myelin sheaths. The activated inflammatory response system might contribute to BD pathophysiology by hampering structural connectivity in critical cortico-limbic networks.