Conference Agenda

Introduction: Bipolar disorder (BD) is a severe psychiatric condition with unknown etiology and no established biomarkers. This study aimed to characterize the cerebrospinal fluid (CSF) proteome in BD and identify potential protein biomarkers for the disease.

Method: We employed high-resolution nano-liquid chromatography-mass spectrometry to quantify over 2,000 CSF proteins in a total of 375 individuals from two independent cohorts. Case-control comparisons of protein abundance were conducted, followed by differential abundance analyses across BD subtypes.

Results: A total of 135 proteins were associated with BD in the first cohort (5% FDR), with 41 replicated in the second cohort. Compared to controls, BD cases exhibited lower abundance of brain-expressed proteins involved in neuronal cell-cell-interactions and synaptic functions (e.g., APP, NPTX2, NRXN1, NRXN2), and higher abundance of peripherally expressed proteins involved in for example lipid metabolic processes (e.g., APOA4, APOL1), complement pathways (e.g., C4, C4BPA) and extracellular matrix organization (e.g., VTN, LUM). Differential abundance analyses across the bipolar subtypes revealed that these alterations were primarily driven by the BD1 subtype of bipolar disorder.

Conclusion: This study represents the first large-scale untargeted profiling of the CSF proteome in BD. The identified proteins suggest potential contributions from both neuronal and peripheral processes to BD pathophysiology. Further studies are warranted to validate these findings and elucidate the functional roles of these proteins in BD.

Background: While displaying the in vitro pharmacological profile of a dopamine D₂ antagonist and partial 5-HT_2A agonist, the so-called dopamine stabiliser (-)-OSU6162 enhances locomotion in inactive animals but dampens it in active animals. While this profile could be due to preferential antagonism of dopaminergic autoreceptors combined with antagonism of a subpopulation of postsynaptic D₂ receptors, it cannot explain the plethora of behavioural effects displayed by (-)-OSU6162, including antidepressant-like, anxiolytic-like, and antipsychotic-like effects, while (unlike other D₂ antagonists) never causing catalepsy.

Objectives: To explore the mechanisms of action of (-)-OSU6162.

Methods: First, the interaction between (-)-OSU6162 and the dopamine releaser amphetamine with respect to impact on extracellular dopamine levels (assessed using in vivo microdialysis) and on locomotor activity was assessed in rats. Second, the impact of (-)-OSU6162 on locomotion in mice treated with the D₁/D₂ agonist apomorphine after having been deprived of presynaptic dopamine activity by reserpine pre-treatment was explored.

Results: (-)-OSU6162 potentiated an amphetamine-induced increase in extracellular dopamine levels in the dorsal rat striatum but blocked the locomotor response to amphetamine. While these results might suggest that (-)-OSU6162 antagonizes both D₂ autoreceptors and postsynaptic D₂ receptors, the compound did not counter a locomotor-stimulatory effect of the D₁/D₂ agonist apomorphine in monoamine-depleted mice. On the contrary, the combined administration of (-)-OSU6162 and apomorphine caused a synergistic impact on locomotion that was blocked by the 5-HT_2A antagonist MDL 100907. Arguing against (-)-OSU6162 acting merely as a 5-HT_2A partial agonist in this situation, a similar synergistic effect could however not be achieved with the combined treatment of apomorphine and the 5-HT_2A agonist psilocybin.

Conclusion: The results suggest the impact of (-)-OSU6162 to include the interaction of antagonism of D₂autoreceptors, positive allosteric modulation of postsynaptic D₂ receptors, and partial agonism of the 5-HT_2Areceptor.

Background: The Karolinska Schizophrenia Project (KaSP) focuses on exploring the underlying mechanisms of schizophrenia. The project recruits first-episode psychosis (FEP) patients and healthy controls (HC) for comparative studies.

Objectives: The project's goals are to assist in schizophrenia diagnosis, predict the efficacy of antipsychotic treatments, and understand psychosis pathophysiology by examining related metabolic pathways and proteomics signatures.

Methods: Our recent study employed untargeted metabolomics, utilizing ultra-high pressure liquid chromatography and time-of-flight mass spectroscopy. We analyzed cerebrospinal fluid (CSF) and serum samples from 25 FEP patients at baseline and 18-month follow-up, alongside samples from 21 HCs. In another study, we sought to investigate the CSF proteomic signatures associated with FEP. Using 16-plex tandem mass tag (TMT) mass spectrometry, we examined the relative protein quantification of CSF samples from 15 individuals diagnosed with FEP and 15 age-and-sex-matched healthy controls (HC). We have used unsupervised and supervised multi-omics integration to methods to identify signature proteins in CSF.

Findings: The metabolomic analysis revealed distinct psychosis-associated metabolites in both CSF (eight) and serum (32). Notably, increased CSF serotonin (5-HT) levels were observed in FEP patients. This finding was further validated in an extended cohort through reversed-phase high-pressure liquid chromatography. The proteomics analysis revealed sixteen differentially expressed proteins. Unsupervised multi-omics approach revealed different factors associated with immune response and complement activation systems which was not revealed in single omics data modalities.

Conclusion: The integrative multi-omics analysis offers important insights into the pathophysiology of schizophrenia. Through a comprehensive approach combining both metabolomics and proteomics, we have identified important pathway that could help us understand schizophrenia pathophysiology. Notably, the application of unsupervised and supervised multi-omics integration methods unveiled critical factors related to immune response and complement activation systems, aspects not discernible through single-omics analyses.

Background: Chemotherapy cause severe sickness and cognitive disturbances (chemo-brain) in up to 75% of the patients receiving this treatment. These adverse effects are believed to be caused in part by an imbalance of pro- and anti-inflammatory cytokines and it has also been shown that the microbiota modulate the efficacy and toxicity of chemotherapy. Parasitic worms (helminths) can reduce inflammation, restore the gut barrier, and beneficially modulate the host microbiota. Molecules derived from parasite. Helminths are a novel source of biologic therapies, which directly modulate the immune response and microbiota.

Objectives: The objective of this project is to examine the protective effects of the parasite on chemotherapy-induced sickness and chemo-brain. Further, we will explore which underlying biological mechanims that are altered by the parasite. The ultimate goal is to alleviate chemotherapy-induced sickness and chemo-brain.

Methods: Once weekly for 4 weeks, Sprague-Dawley rats are treated with the chemotherapy drug doxorubicin (DOX) and parasite or vehicle. During the DOX+PARASITE treatment the animals are housed in Noldus Phenotyper cages which allow us to record home-cage behaviour. Subsequently, the animals undergo a battery of behavioural tests and tissue is collected. Microbiome, inflammatory markers, and monoamine levels will be examined.

Results: We have shown that parasite ameliorates chemotherapy induced weightloss – a proxy for sickness. We expect parasite to improve cognitive deficits caused by DOX and potentially depressive- and anxiety-like behaviour as well, likely through direct effects on the microbiota and restoration of gut integrity via replenishment of intestinal stem cells

Conclusion: Helminth improve chemotherapy-induced sickness and we expect that cognitive disturbances (chemo-brain) are also improved.

Examining the premise that changes in hormone levels impact mood, as evidenced in conditions such as premenstrual dysphoric disorder, perinatal depression, postpartum depression, and premenopausal depression, along with the consistent observation that major depressive disorder disproportionately affects women, with a lifetime prevalence twice as high as that in men, our objective was to investigate whether antidepressants might engage with the biological elements of this system, particularly estrogen receptor alpha (ERα), to produce their therapeutic effects.

We suggested that antidepressants may alter the activity of ERα. Furthermore, we proposed the possibility of a direct interaction with ERα for all antidepressants, irrespective of their pharmacological classification, with rapid-acting antidepressants preferentially interacting with membrane ERα and initiating non-genomic signaling.

We utilized various molecular and computational tools to demonstrate that ERα may mediate the effect of antidepressants. To further assess whether rapid-acting antidepressants preferentially affect membrane ERα, distinct genes whose expressions are dependent on the activation of either membrane-initiated or nuclear-initiated ERα signaling were studied. Finally, we studied the impact of essential heat-shock proteins in the response evoked by treatment with antidepressants.

Our findings suggested that almost all antidepressants are able to directly interact with ERα, in silico. Subsequent in vitro studies revealed that ketamine and imipramine increased the phosphorylation of ERα, an effect mitigated by pretreatment with fulvestrant. Inhibition of the palmitoylation process, through which ERα is localized to the membrane, resulted in reduced receptor activation, supporting the involvement of membrane-bound ERα in the observed molecular impact exerted by antidepressants. Rapid activation of ERα in MCF-7 cells further corroborated the potential involvement of extranuclear ERα that are associated with immediate estrogen signaling. These findings were also confirmed by employing immunoassay techniques and confocal microscopy.

In an attempt to explore whether estrogen can influence the antidepressant-like behavioral effects of ketamine in a selectively bred genetic animal model of depression, we examined whether such effects could be sex-specific and whether they varied across the estrous cycle in female depressed and non-depressed rats. However, we could not observe any significant sex-specific or estrous cycle-specific behavioral differences in these animals.

This work emphasizes the role of ERα in mood regulation, identifies ERα as a therapeutic target, and raises the possibility that the mechanism of action of all antidepressants may converge on sex steroid receptors. While further studies are warranted, targeting sex steroid receptors could hold promise for the development of novel antidepressant treatments.

The link between schizophrenia and dopamine (DA) is well established, and most antipsychotic medications work via DA D2-receptor antagonism. However, negative symptomatology is often either unaffected or exacerbated by treatment with D2-receptor blockade. This, taken together with imagining studies showing a connection between negative symptoms and low dopaminergic activity in the ventral striatum, suggests that negative symptoms might be alleviated by selective manipulation of ventral striatum DA. In this project we wanted to investigate the dopaminergic profiles of known psychosis-generating drugs versus non-psychosis-generating drugs in the ventral (nucleus accumbens, nAc) and dorsal subregions (dorsomedial striatum, DMS) of the striatum, and to find a way by which we can selectively elevate DA in the nAc in Wistar rats. To this end we used a custom-made dual microdialysis probe which allows for simultaneous sampling of the two brain regions within the same animal. In the first set of experiments, we investigated the dopaminergic profiles of psychosis-generating and non-psychosis-generating drugs. We found that psychosis-generating drugs (amphetamine and cocaine) robustly elevated extracellular DA in both nAc and DMS, whereas the other substances (ethanol, nicotine and morphine) primarily affected DA in the nAc. Building on this, and previous findings showing that, when combined, ethanol and nicotine have an additive effect on accumbal DA, we decided to attempt a selective manipulation of nAc DA by utilising similar pathways by which ethanol and nicotine elevate DA. To do we combined the partial nicotine acetylcholine receptor agonist varenicline with the glycine reuptake inhibitor Org24598. We showed that combination of partial nicotine agonism and glycine reuptake inhibition results in a pronounced elevation of nAc DA, whereas there was no significant effect on DMS DA. This suggest a pathway through which dopamine can be selectively manipulated as a potential route of treatment for negative symptoms in schizophrenia.