NAD+/NADH dysregulation revealed by 31P‐MRS in the Gclm KO mouse.
Radek Skupienski (Lausanne | CH)
Schizophrenia (SZ), a major psychiatric disease, is a developmental syndrome involving decreased connectivity deriving from both genetic and environmental factors. The reciprocal interaction of oxidative stress and NMDAR hypofunction leading to impairment of inhibitory interneurons and neural synchronization may represent one core pathophysiology. Nicotinamide Adenine dinucleotide NADH (reduced form) and NAD+ (oxidized form) are cofactors of energy producing pathways. Their ratio RX (NAD+/NADH) reflects the cellular oxidoreductive state. Oxidative stress and redox dysregulation have been suggested in various neurological diseases including Schizophrenia, Parkinson’s and Alzheimer’s diseases as well as aging. The in vivo measurement of redox state and NAD contents has recently been available and demonstrated in cat and human brains by 31P-MRS. We previously demonstrated the feasibility of such measurement in mouse brain, however in vivo measurement of these indices during brain development has never been attempted.
With the aim to identify biomarkers for early detection of SZ, we investigated in vivo the redox and glutamate (Glu) systems during neurodevelopment in the glutathione (GSH) deficient gclm-KO mice. The NAD+/NADH (RX) and the neurochemical profile were determined using 31P- and 1H-MRS respectively.
In wild type (WT) mice, an increase of RX was observed from postnatal day P20 to P250, due to an increase of [NAD+] and a decrease of [NADH]. Gclm-KO mice showed a much more pronounced increase of RX during development which was significantly higher as compared to WT at P90. Consistently high redox-ratio, reflecting high frontal oxidative status was associated with low GSH level in gclm-KO mice. Glutamine/Glutamate ratio was negatively correlated with GABA in WT animals at P90 while the correlation was disrupted in gclm-KO. Moreover at P40 low GABA was associated with low NADH in glcm-KO. This may reflect an impairment of the inhibitory circuitry.
In this study we demonstrated first: the feasibility of longitudinal measurement of NAD+, NADH and RX in mice brains during development at 14.1T which opens widely the prospect of studying longitudinally the energy metabolism and redox dysfunction in mouse models of brain pathologies. Secondly we are on the good way to identify molecular mechanism affecting brain development and regulation in the gclm-KO mice, which could be relevant for the pathophysiology of schizophrenia.
Mitochondrial dysfunction in Early Psychosis Patients: a translational study
Ines Khadimallah (Prilly-Lausanne | CH)
Mitochondria play a pivotal role in regulating cellular functions including bioenergetics, calcium homeostasis, redox signaling, and apoptotic cell death, all crucial for neuronal activity, sprouting, development and survival. Impairments in mitochondrial structure, network dynamics, electron transport system activity, transcriptome, proteome and in sequence of mitochondrial-relevant genes both in brain and in peripheral cells are implicated in schizophrenia (SZ). As oxidative stress appears as a common hub in SZ pathophysiology, it is vital to understand the interplay between mitochondrial dysfunction and redox impairment, and to clarify if redox susceptibility confers a predisposition to mitochondrial impairments in SZ patients. Here we investigated (1) oxidative stress impact on mitochondrial integrity in the redox dysregulated Gclm-KO mice (70% decrease in glutathione level and oxidative stress from juvenile stage until adulthood); (2) mitochondrial response to stress in early psychosis patients (EPP); (3) impact of redox susceptibility (GCLC high-risk genotypes) on mitochondrial markers.
Effect of oxidative stress on mitochondrial morphology: ultrastructural changes in mPFC of Gclm-KO mice characterized by electron microscopy.
Fibroblasts from EPP and healthy controls were used to assess mitochondrial characteristics (complex 1 subunit alterations, fusion/fission and pro-/anti-apoptotic markers) in basal and oxidative stress conditions.
We found an increased of mitochondrial damage in Gclm-KO mice compared to wild-type mice in parallel to oxidative stress, suggesting impaired energy production and ROS generation.
Profiling of mitochondrial response to oxidative stress in EPP fibroblasts showed altered levels of mitochondrial markers. Discriminant analysis revealed that the response to oxidative stress of mitochondrial markers efficiently separate EPP from controls and individuals with different redox susceptibility (i.e. different polymorphism in GCLC gene). Mitochondria profiling in patients’ fibroblasts thus appears as a powerful approach for patients’ stratification.
These results indicate that mitochondrial abnormalities as observed in SZ mouse model and patients may result from a redox dysregulation. These abnormalities may enhance ROS production, impair mitochondria clearance and motility and altogether lower energy production at sites with high energetic demand (e.g. at synapses or in parvalbumin interneurons).
N-acetyl-cysteine treatment and environmental enrichment reversed the long-lasting effect of oxidative stress on PVI circuitry: relevance for schizophrenia
Daniella Dwir (Prilly | CH)
A hallmark of the pathophysiology of schizophrenia is a dysfunction of parvalbumin-expressing fast-spiking interneurons (PVI), which are essential for neuronal synchrony during sensory and cognitive processing. Oxidative stress and inflammation, as observed in schizophrenia, affects the highly metabolically active PVI. Some schizophrenia patients have decreased brain glutathione (GSH) levels due to genetic and functional origin. GSH dysregulation, by increasing vulnerability to oxidative stress and inflammation during early development leads to impaired cortical circuitry, specifically the PVI and the perineuronal nets (PNN) that surround them. We tested whether a combined treatment of N-acetyl-cysteine (NAC) and enriched environment (EE), during adolescent, prevents the deleterious effect of oxidative insult on PVI and PNN.
We used a transgenic mouse model with GSH deficit (GCLM KO) that shows SZ related phenotype, increased oxidative stress and microglia activation. GCLM KO and WT mice were treated with a dopamine reuptake inhibitor, the GBR-12909 dihydrochloride (GBR), to induce an additional oxidative stress, from postnatal day (PND) 10 to 20. Then, GBR-injected mice were subjected to NAC and EE during adolescent period. Finally, morphological and functional analysis were conducted on adult animals.
Here, we confirmed previous findings that an additional oxidative stress (GBR) in early postnatal days (P10-20) led to long-lasting effects in adult GCLM KO: increase in oxidative stress, activation of microglia, increase in MMP9-IR, and PVI and PNN impairment. These effects were completely reversed by the combination of NAC treatment (given between P21-35) and EE (during P35-56). Interestingly, MMP9-IR was also reversed by NAC treatment alone. The fast rhythmic oscillations reflecting neuronal synchronization of PVI was decreased in the GBR-treated GCLM KO, and recovered by NAC/EE.
Thus, an early oxidative insult induces long-lasting effects on PVI and PNN, which can be reversed by a combined NAC and EE, even after the challenge. In analogy, individuals carrying genetic risks to redox dysregulation potentially vulnerable to early-life insults could benefit from a combined pharmacological and psycho-social therapy.
Correlation of microglial activation with white matter changes in dementia with Lewy bodies
Nicolas Nicastro (Cambridge, United Kingdom | GB)
Aims: Dementia with Lewy bodies (DLB) is the second-leading degenerative dementia after Alzheimer’s disease. Neuropathologically, it is characterized by alpha-synuclein protein deposition with variable degree of concurrent Alzheimer pathology. Neuroinflammation is increasingly recognized as a significant contributor of degeneration. We aimed to examine the relationship between microglial activation as measured with [11C]-PK11195 brain PET and MR diffusion tensor imaging (DTI) in DLB.
Methods: nineteen clinically probable DLB and 20 similarly aged controls underwent structural MRI with T1-weighted and 3T DTI sequences. Eighteen DLB subjects also underwent [11C]-PK11195 PET imaging. Tract-Based Spatial Statistics (TBSS) were performed to compare DTI parameters in DLB relative to controls and identify associations of [11C]-PK11195 binding with white matter integrity.
Results: TBSS showed widespread changes in all DTI parameters in the DLB group compared to controls (Threshold Free Cluster Enhancement (TFCE) p < 0.05). [11C]-PK11195 binding in parietal cortices also correlated with widespread lower mean and radial diffusivity (TFCE p < 0.05).
Conclusion: Our study demonstrates that higher PK11195 binding is associated with a relative preservation of white matter, positioning neuroinflammation as a potential early marker in the DLB pathogenic cascade.
Slow wave promotes sleep-dependent plasticity during stroke recovery
Laura Facchin (bern | CH)
Aim: Clinical and experimental studies suggest a positive role for sleep in brain plasticity during stroke recovery. Here, we investigate the role of Slow Wave (SW) oscillations during sleep on motor recovery following ischemic stroke using optogenetic techniques and in vivo electrophysiology in mice.
Methods: Ischemic stroke was caused in wild type mice using middle cerebral artery occlusion (MCAo). Following injections of CamkII-ChR2-EYFP (ChR2), CamkII-ArchT-EYFP (ArchT) and CamkII-mCherry (control) adeno-associated viruses (AAV) within the peri-lesional primary somatosensory forelimb (S1FL) cortex, SW-like oscillations were induced by optic stimulation of transfected pyramidal neurons. Randomly distributed single light pulses were delivered for 2 h sessions from post-stroke day 5, and consecutively every day until post-stroke day 15. Behavioural tests at post-stroke days 4, 7, 10 and 15 were used to assess the effect of optogenetically evoked SW on motor outcomes. The presence of puncta positive for the pre-synaptic marker vesicular glutamate transporter type 1 (Vglut1) and the post-synaptic density marker 95 (PSD-95) as a measure of axonal sprouting following MCAo and optogenetic SW-like oscillations induction.
Results: We showed that MCAo induced an increased amount of NREM sleep following ischemic stroke, where spontaneous ipsilesional SW where decreased in amplitude and positive slope compared to control animals. During optogenetic sessions, both ChR2 and ArchT stimulations of S1FL pyramidal neurons successfully induced SW sleep-like responses in ipsilateral and contralateral electroencephalography (EEG) traces. Behavioural testing showed that optogenetically-evoked SW significantly improved the recovery of fine motor movement as compared to control mice. Finally, SWs like evoked brain oscillations during NREM sleep induced increased axonal sprouting within both ipsilateral and contralateral hemispheres.
Conclusion: In line with the literature, our results suggest a positive role of sleep in motor recovery following ischemic stroke. Moreover, optogenetically-evoked SW sleep-like oscillations, targeting the activity of pyramidal neurons in the peri-lesional cortex, significantly promote functional outcomes after stroke and induced axonal sprouting in the ipsilateral as well as in the contralateral hemispheres.
Prediction of long-term outcomes in early psychosis: a new approach from topology
Margot Fournier (Prilly-Lausanne | CH)
Clinical and biological markers that quantify disease course or response to medication play a crucial role in treatment decision. The clinical heterogeneity of patients in the early phase of psychosis hampers the identification of such markers. Stratification is therefore a key step to tailor intervention and to improve functional deficits which critically contribute to long-term quality of life.
Topological data analysis (TDA) is a powerful approach to studying the shape of biological datasets. We applied TDA to stratify early psychosis patients according to their symptoms and assessed the predictive power of this stratification for long-term outcomes. We then searched for a biosignature of the groups, focusing on redox markers to as redox dysregulation/oxidative stress is proposed as a pathophysiological hub in schizophrenia.
• Subjects: early psychosis patients (mean age 25y) recruited from the Lausanne “Treatment and early intervention program”; test cohort, n=101; replication cohort, n=93.
• Stratification: the TDA algorithm Mapper was applied to the 30 item scores of the Positive And Negative Syndrome Scale.
• Outcomes after 3-year follow-up: scores of global or social and occupational functioning, the percentage of patients in symptomatic remission, working, or living independently.
• Metabolic profiling: blood levels of 29 amino acids and derivatives; activity of 3 antioxidant enzymes.
Three groups of patients were identified by TDA: group A, characterized by an overall low level of symptom, group B, by high positive and negative symptoms, and group C, by high negative symptoms. Importantly, group A had a high predictive value for good outcomes: patients in this group functioned better at follow-up than those from group B and C. We confirmed these results in the replication cohort. The metabolic biosignature suggests a better regulation of the anti-oxidant defenses in patients with better outcome (group A) and a deficient redox homeostasis in groups B and C.
Unsupervised data-driven topological analysis allowed patients’ stratification into clinically relevant subgroups and the detection of patients at risk for poor functional outcomes. This stratification was robust and its predictive power surpassed the one obtained with a standard clustering method. This approach, combined with mechanism based metabolic profile, should pave the way to personalized functional-disability preventive strategies at early stages of the disease.
Amnestic syndrome in idiopathic Normal Pressure Hydrocephalus
Alma Lingenberg (Geneva | CH)
Background: Executive functions are classically impaired in idiopathic Normal Pressure Hydrocephalus (iNPH); however, some iNPH patients are also presenting with an amnestic syndrome of the hippocampal type similar to Alzheimer’s disease (AD). This study aims to disentangle the predictive factors of this amnestic syndrome in iNPH, especially the association with abnormal CSF biomarkers for AD.
Methods: One hundred consecutive iNPH patients (77.0 ± 6.6 years; 38% female, 12.0 ± 3.5 education years) assessed in the Division of Neurology, Geneva University Hospitals from 2011 to 2019 were included in this cross-sectional study. Episodic memory was evaluated with the Free and Cued Selective Recall Test (FCSRT) before CSF tap test. The main outcome was the sum of total recall scores on the FCSRT, with a value of < 40/48 indicating the presence of an amnestic syndrome of the hippocampal type. Independent samples t-tests or Pearson’s Chi-squared tests, as appropriate, were used to compare patients with and without an amnestic syndrome. Predictors of the memory profile were examined using post-imputation linear regressions.
Results: Thirty-eight iNPH patients (38%) were classified as amnestic (FCSRT sum of total recalls < 40/48). The amnestic iNPH patients were significantly less educated (10.2 ± 3.5 versus 13.1 ± 3.0 years, p-value < 0.001) and presented a more severe cognitive impairment (MMSE: 22.6 ± 3.3 versus 25.8 ± 2.8; p-value < 0.001) than the non-amnestic patients; they had a similar disease duration, white matter abnormalities and CSF biomarkers levels for AD. The level of education was associated with the FCSRT sum of total recalls in the multivariate model (β = 0.63; 95% CI [0.15;1.12]; p = 0.011), as well as the MMSE (β = 0.93; 95% CI [0.35;1.52]; p = 0.002), but not CSF biomarkers for AD.
Conclusions: Education and global cognition, but not a comorbid AD pathology, are associated with an amnestic syndrome of the hippocampal type in iNPH. These findings suggest that amnestic syndrome in iNPH does not reflect an underlying AD comorbidity that is frequent in patients with iNPH.
Systemic and CNS neuroinflammation is associated with neuropsychiatric symptoms
Christopher Clark (Thônex - Ge | CH)
AIMS: Systemic and CNS inflammation are linked to neuropsychiatric symptoms (NPS). Neuroinflammation is also associated with cerebrovascular and neurodegeneration processes and cognitive decline. Here, we sought to identify cerebrospinal fluid (CSF) and peripheral blood serum inflammation marker signatures associated with NPS in older subjects while taking into account cognitive impairment and core Alzheimer’s disease (AD) pathology. Associations between identified markers and structural imaging data were also assessed to establish their link with regional neurodegeneration.
METHODS: We administered the neuropsychiatric inventory (NPI-Q) questionnaire and quantified a panel of 28 neuroinflammatory markers and albumin using sandwich immunoassays in both CSF and serum as well as the levels of AD CSF biomarkers Aβ1-42, tau and p-tau181 in 87 older community-dwelling subjects with normal cognition or with cognitive impairment. Additionaly, morphometric data was obtained from magnetic resonance imaging scans in the same cohort. Regression models selected molecules associated with NPI-Q scores.
RESULTS: Mean age was 70 years, MMSE score 27, and NPI-Q score 2.5. The occurrence of NPS was associated with a specific combination of inflammatory markers in CSF independently of cognitive status: soluble intracellular adhesion molecule-1, C-reactive protein and IFN-γ induced 10kDa protein. This signature interacts with AD pathology at the level of soluble intracellular adhesion molecule-1 only. Severity of NPS was associated with thymus and activation-regulated chemokine. In serum, a distinct combination of markers including interleukin-6 and C-reactive protein are associated with NPS. Correcting these models for the CSF/serum albumin ratio, considered here as a marker of blood-brain barrier permeability, indicated that these signatures originate in the CNS. Specific inflammatory markers are also associated with individual NPI-Q categories. Furthermore, soluble intracellular adhesion molecule-1 was robustly associated with volumetric changes in hippocampus and the third ventricle. Interestingly, volume changes in these two areas are also associated with the occurrence of NPS.
CONCLUSION: This study shows that specific CSF and serum inflammatory marker signatures are associated with NPS. These signatures are independent of cognitive status, originate in the CNS and can be considered potential biomarkers of NPS and the underlying cerebral pathology.