Salivary Metabolomics Reveals that Metabolic Alterations Precede the Onset of Schizophrenia.

Schizophrenia is a complex and highly heterogeneous mental illness with a prodromal period called clinical high risk (CHR) for psychosis before onset. Metabolomics is greatly promising in analyzing the pathology of complex diseases and exploring diagnostic biomarkers. Therefore, we conducted salivary metabolomics analysis in 83 first-episode schizophrenia (FES) patients, 42 CHR individuals, and 78 healthy controls with ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The mass spectrometry raw data have been deposited on the MetaboLights (ID: MTBLS3463). We found downregulated aromatic amino acid metabolism, disturbed glutamine and nucleotide metabolism, and upregulated tricarboxylic acid cycle in FES patients, which existed even in the CHR stage and became more intense with the onset of the schizophrenia. Moreover, differential metabolites can be considered as potential diagnostic biomarkers and indicate the severity of the different clinical stages of disease. Furthermore, three disordered pathways were closely related to peripheral indicators of inflammatory response, oxidative stress, blood-brain barrier damage, and salivary microbiota. These results indicate that the disorder of oral metabolism occurs earlier than the onset of schizophrenia and is concentrated and intensified with the onset of disease, which may originate from the dysbiotic salivary microbiota and cause the onset of schizophrenia through the peripheral inflammatory response and redox system, suggesting the importance of oral-brain connection in the pathogenesis of schizophrenia.

Hypoxia-induced cysteine metabolism reprogramming is crucial for the tumorigenesis of colorectal cancer.

Metabolic reprogramming is a hallmark of human cancer, and cancer-specific metabolism provides opportunities for cancer diagnosis, prognosis, and treatment. However, the underlying mechanisms by which metabolic pathways affect the initiation and progression of colorectal cancer (CRC) remain largely unknown. Here, we demonstrate that cysteine is highly enriched in colorectal tumors compared to adjacent non-tumor tissues, thereby promoting tumorigenesis of CRC. Synchronously importing both cysteine and cystine in colorectal cancer cells is necessary to maintain intracellular cysteine levels. Hypoxia-induced reactive oxygen species (ROS) and ER stress regulate the co-upregulation of genes encoding cystine transporters (SLC7A11, SLC3A2) and genes encoding cysteine transporters (SLC1A4, SLC1A5) through the transcription factor ATF4. Furthermore, the metabolic flux from cysteine to reduced glutathione (GSH), which is critical to support CRC growth, is increased due to overexpression of glutathione synthetase GSS in CRC. Depletion of cystine/cysteine by recombinant cyst(e)inase effectively inhibits the growth of colorectal tumors by inducing autophagy in colorectal cancer cells through mTOR-ULK signaling axis. This study demonstrates the underlying mechanisms of cysteine metabolism in tumorigenesis of CRC, and evaluates the potential of cysteine metabolism as a biomarker or a therapeutic target for CRC.

Identification of adolescent patients with depression via assessment of the niacin skin flushing response.

BACKGROUND: Depressive disorder (DD) affects approximately 20 % of adolescents worldwide, but it is underdiagnosed due to the lack of objective biomarkers. Niacin skin flushing response (NSFR) is an objective and noninvasive biomarker of adult depression; however, its effectiveness has not been assessed in adolescents. METHODS: This study included 198 adolescents with 50 % healthy controls (HC). Linear mixed-effects model and multiple linear regression analyses were performed to assess differences in NSFR between the DD and HC groups. Logistic regression models based on NSFR were constructed, and the area under curve (AUC) was calculated to evaluate the performance of models. Spearman correlations were calculated to assess the relationships between NSFR and disease duration and hormone levels associated with puberty. RESULTS: Adolescents with DD displayed significantly attenuated and delayed NSFR compared to HC. NSFR effectively distinguished DD patients from HC with AUC values of 0.719 (sensitivity = 0.844) and 0.721 (sensitivity = 0.829) determined in the discovery and validation sets, respectively. Within the DD group, the maximum degree of NSFR was negatively correlated with the disease duration (r = -0.28, p = 0.011), and the overall degree of NSFR was positively associated with prolactin (r = 0.29, p = 0.039) and thyroxine (r = 0.29, p = 0.027) levels. LIMITATIONS: Future investigations will be necessary to confirm our results in an independent sample set. CONCLUSIONS: This study provides the first evidence of the utility of NSFR as an objective auxiliary diagnostic biomarker for adolescent depression. It provides new clues to understand the pathophysiology of the disease, and helps promote precise diagnosis, treatment, and prognostic evaluation of adolescent depression.

FAK-mediated phosphorylation at Y464 regulates p85ß nuclear translocation to promote tumorigenesis of ccRCC by repressing RB1 expression.

PI3K regulatory subunit p85s normally stabilizes and regulates catalytic subunit p110s in the cytoplasm. Recent studies show that p110-free p85s in the nucleus plays important roles in biological processes. However, the mechanisms by which p85s translocate into the nucleus remain elusive. Here, we describe the mechanism by which p85ß translocates into the nucleus to promote ccRCC tumorigenesis. Phosphorylation of p85ß at the Y464 by FAK facilitates its nuclear translocation in the kidney through enhancing the binding of p85ß to KPNA1. PIK3R2/p85ß is highly expressed in ccRCC samples and associated with overall survival of ccRCC patients. Nuclear but not cytoplasmic p85ß performs oncogenic functions by repressing RB1 expression and regulating the G1/S cell cycle transition. Nuclear p85ß represses RB1 expression by stabilizing histone methyltransferase EZH1/EZH2 proteins. Last, the FAK inhibitor defactinib significantly suppresses the tumor growth of ccRCC with high p85ß Y464 levels.

Shotgun metagenomics reveals abnormal short-chain fatty acid-producing bacteria and glucose and lipid metabolism of the gut microbiota in patients with schizophrenia.

Evidence has shown that the gut microbiota is closely related to the pathogenesis of schizophrenia, but temporal changes in the gut microbiota of patients with schizophrenia (SZ) during treatment remain unclear. Here, to evaluate temporal changes in the gut microbiota in schizophrenia, we performed whole-genome shotgun metagenomics on fecal samples from 36 healthy controls (HCs) and 19 baseline-period patients, and followed up with patients upon treatment. Compared to that in HCs, beta diversity in SZ was significantly distinct. The genera Bacteroides, Prevotella and Clostridium were the top 3 altered genera between SZ and HCs, and the Bacteroides-Prevotella ratio was significantly increased in SZ. Thirty-three percent of differentially abundant species were short-chain fatty acid (SCFA)-producing bacteria. Functional analysis showed that glucose and lipid metabolism of the gut microbiota was decreased in SZ compared with those in HCs. The abundances of two rate-limiting enzymes in glucose and lipid metabolism, phosphofructokinase (PFK) and acetyl-CoA carboxylase (ACC), were significantly decreased in SZ, and differentially abundant metabolism-related enzymes were significantly associated with SCFA-producing bacteria. Next, we found that the abundance of SCFA-producing bacteria also changed after treatment and that Clostridium was significantly negatively correlated with the total positive and negative syndrome scale (PANSS) score in patients. Functional analysis showed that glycoside hydrolase family 30 incrementally increased in abundance during treatment and were significantly associated with SCFA-producing bacteria. Our findings help to provide evidence for the role of gut microbiota in the occurrence and development of schizophrenia.

Targeted metabolomics reveals aberrant profiles of serum bile acids in patients with schizophrenia.

Emerging evidence indicates that bile acids (BAs), which are signaling molecules that regulate metabolism and inflammation, appear to be dysregulated in schizophrenia (SZ). Further investigation is warranted to comprehensively characterize BA profiles in SZ. To address this, we analyzed serum BA profiles in 108 drug-free patients with SZ and in 108 healthy controls (HCs), divided into a discovery set (n = 119) and a validation set (n = 97), using ultraperformance liquid chromatography triple quadrupole mass spectrometry. Forty serum BAs were detected and absolutely quantified using calibration curves. Global BA profiling showed differences in SZ and HC groups in both discovery and validation sets. The concentrations of chenodeoxycholic acid, ursodeoxycholic acid, 3ß-chenodeoxycholic acid, 7-ketolithocholic acid, 3-dehydrocholic acid, total BAs, and unconjugated BAs were significantly lower in patients with SZ compared with HCs in the two sample sets. The BA deconjugation potentials by gut microbiota and the affinity index of the farnesoid X receptor (FXR) were notably decreased in SZ patients compared to those of HCs. Conjugated BAs and BA deconjugation potentials differed in SZ patients with first versus recurrent episodes, although similar BA profiles were observed in both groups. In addition, a panel of 8 BA variables acted as a potential auxiliary diagnostic biomarker in discriminating SZ patients from HCs, with area under the curve values for receiver operating characteristic curves of 0.758 and 0.732 and for precision-recall curves of 0.750 and 0.714 in the discovery and validation sets, respectively. This study has provided compelling evidence of comprehensive characteristics of circulating BA metabolism in patients with SZ and promoted a deeper understanding of the role of BAs in the pathophysiology of this disease, possibly via the gut microbiota-FXR signaling pathway.

Impaired Membrane Lipid Homeostasis in Schizophrenia.

BACKGROUND AND HYPOTHESIS: Multiple lines of clinical, biochemical, and genetic evidence suggest that disturbances of membrane lipids and their metabolism are probably involved in the etiology of schizophrenia (SCZ). Lipids in the membrane are essential to neural development and brain function, however, their role in SCZ remains largely unexplored. STUDY DESIGN: Here we investigated the lipidome of the erythrocyte membrane of 80 patients with SCZ and 40 healthy controls using ultra-performance liquid chromatography-mass spectrometry. Based on the membrane lipids profiling, we explored the potential mechanism of membrane phospholipids metabolism. STUDY RESULTS: By comparing 812 quantified lipids, we found that in SCZ, membrane phosphatidylcholines and phosphatidylethanolamines, especially the plasmalogen, were significantly decreased. In addition, the total polyunsaturated fatty acids (PUFAs) in the membrane of SCZ were significantly reduced, resulting in a decrease in membrane fluidity. The accumulation of membrane oxidized lipids and the level of peripheral lipid peroxides increased, suggesting an elevated level of oxidative stress in SCZ. Further study of membrane-phospholipid-remodeling genes showed that activation of PLA2s and LPCATs expression in patients, supporting the imbalance of unsaturated and saturated fatty acyl remodeling in phospholipids of SCZ patients. CONCLUSIONS: Our results suggest that the mechanism of impaired membrane lipid homeostasis is related to the activated phospholipid remodeling caused by excessive oxidative stress in SCZ. Disordered membrane lipids found in this study may reflect the membrane dysfunction in the central nervous system and impact neurotransmitter transmission in patients with SCZ, providing new evidence for the membrane lipids hypothesis of SCZ.

Salivary microbiome profiling reveals a dysbiotic schizophrenia-associated microbiota.

Schizophrenia is a debilitating mental disorder and often has a prodromal period, referred to as clinical high risk (CHR) for psychosis, prior to the first episode. The etiology and pathogenesis of schizophrenia remain unclear. Despite the human gut microbiome being associated with schizophrenia, the role of the oral microbiome, which is a vital player in the mouth-body connection, is not well understood. To address this, we performed 16S rRNA gene sequencing to investigate the salivary microbiome in 85 patients with drug-naïve first-episode schizophrenia (FES), 43 individuals at CHR, and 80 healthy controls (HCs). The salivary microbiome of FES patients was characterized by higher α-diversity and lower ß-diversity heterogeneity than those of CHR subjects and HCs. Proteobacteria, the predominant phylum, was depleted, while Firmicutes and the Firmicutes/Proteobacteria ratio was enriched, in a stepwise manner from HC to CHR to FES. H2S-producing bacteria exhibited disease-stage-specific enrichment and could be potential diagnostic biomarkers for FES and CHR. Certain salivary microbiota exhibited disease-specific correlation patterns with symptomatic severities, peripheral pro-inflammatory cytokines, thioredoxin, and S100B in FES. Furthermore, the metabolic functions from inferred metagenomes of the salivary microbiome were disrupted in FES, especially amino acid metabolism, carbohydrate metabolism, and xenobiotic degradation. This study has established a link between salivary microbiome alterations and disease initiation and provided the hypothesis of how the oral microbiota could influence schizophrenia.

Dysregulation of phospholipase and cyclooxygenase expression is involved in Schizophrenia.

BACKGROUND: Schizophrenia (SZ) is a severe mental disease with highly heterogeneous clinical manifestations and pathological mechanisms. Schizophrenia is linked to abnormalities in cell membrane phospholipids and blunting of the niacin skin flush response, but the associations between these phenotypes and its molecular pathogenesis remain unclear. This study aimed to describe the PLA2/COX pathway, the key link between phospholipids and niacin flush, and to illustrate the pathogenic mechanisms in schizophrenia that mediate the above phenotypes. METHODS: A total of 166 patients with schizophrenia and 54 healthy controls were recruited in this study and assigned to a discovery set and a validation set. We assessed the mRNA levels of 19 genes related to the PLA2/COX cascade in leukocytes by real-time PCR. Plasma IL-6 levels were measured with an ELISA kit. Genetic association analysis was performed on PLA2G4A and PTGS2 to investigate their potential relationship with blunted niacin-skin response in an independent sample set. FINDINGS: Six of the 19 genes in the PLA2/COX pathway exhibited significant differences between schizophrenia and healthy controls. The disturbance of the pathway indicates the activation of arachidonic acid (AA) hydrolysis and metabolization, resulting in the abnormalities of membrane lipid homeostasis and immune function, further increasing the risk of schizophrenia. On the other hand, the active process of AA hydrolysis from cell membrane phospholipids and decreased transcription of CREB1, COX-2 and PTGER4 may explain the reported findings of a blunted niacin response in schizophrenia. The significant genetic associations between PLA2G4A and PTGS2 with the niacin-skin responses further support the inference. INTERPRETATION: These results suggested that the activation of AA hydrolysis and the imbalance in COX-1 and COX-2 expression are involved in the pathogenesis of schizophrenia and blunting of the niacin flush response. FUNDING: This work was supported by the National Key R&D Program of China (2016YFC1306900, 2016YFC1306802); the National Natural Science Foundation of China (81971254, 81771440, 81901354); Interdisciplinary Program of Shanghai Jiao Tong University (ZH2018ZDA40, YG2019GD04, YG2016MS48); Grants of Shanghai Brain-Intelligence Project from STCSM (16JC1420500); Shanghai Key Laboratory of Psychotic Disorders (13DZ2260500); and Shanghai Municipal Science and Technology Major Project (2017SHZDZX01); China Postdoctoral Science Foundation (2018M642029, 2018M630442, 2019M661526, 2020T130407); Natural Science Foundation of Shanghai (20ZR1426700); and Startup Fund for Youngman Research at SJTU (19 × 100040033).

Decreased serum apolipoprotein A4 as a potential peripheral biomarker for patients with schizophrenia.

Recent evidence supports an association between lipid metabolism dysfunction and the pathology of schizophrenia which has led to the search for peripheral blood-based biomarkers. The purpose of this study was to investigate the proteins involved in lipid metabolism (especially apolipoprotein) and to explore their potential as biomarkers for schizophrenia. Using multiple reaction monitoring mass spectrometry (MRM-MS), we quantified 22 proteins in serum samples of 109 healthy controls (HCs) and 111 patients with schizophrenia (SCZ), who were divided into discovery and validation sets. We found serum apolipoprotein A4 (ApoA4) to be significantly decreased in SCZ patients compared to HCs (p=1.61E-05). Moreover, the serum ApoA4 level served as an effective diagnostic tool, achieving area under the receiver operating characteristic curves (AUROC) of 0.840 in the discovery set and 0.791 in the validation set. Additionally, apolipoprotein F (ApoF), angiotensinogen (AGT), and alpha1-antichymotrypsin (ACT) levels were significantly higher in patients with schizophrenia than in healthy controls. These proteins combined with ApoA4, provided higher diagnostic accuracy for schizophrenia in the discovery set (AUROC=0.901) and in the validation set (AUROC=0.879). Our results suggest that the serum level of ApoA4 is a novel potential biomarker for schizophrenia. The proteins identified in this study expand the pool of biomarker candidates for schizophrenia and may be linked to the underlying mechanism of the disease.

Attenuated and delayed niacin skin flushing in schizophrenia and affective disorders: A potential clinical auxiliary diagnostic marker.

AIM: Schizophrenia and affective disorders all show high heterogeneity in clinical manifestations. A lack of objective biomarkers has long been a challenge in the clinical diagnosis of these diseases. In this study, we aimed to investigate the performance of niacin skin flushing in schizophrenia and affective disorders and determine its clinical potential as an auxiliary diagnostic marker. METHODS: In this case-control study, niacin skin-flushing tests were conducted in 613 patients (including 307 schizophrenia patients, 179 bipolar disorder patients, and 127 unipolar depression patients) and 148 healthy controls (HCs) with a modified method. Differences in niacin skin-flushing responses were compared with adjustment for gender, BMI, age, nicotine dependence, alcohol consumption and educational status. A diagnostic model was established based on a bivariate cut-off. RESULTS: Schizophrenia and affective disorders showed similar performance of niacin bluntness, characterized by attenuated flushing extent and reduced flushing rate. An innovative bivariate cut-off was established according to these two features, by which we could identify -patients with either schizophrenia or affective disorders from HCs with a sensitivity of 55.28%, a specificity of 83.56% and a positive predictive value of 93.66%. CONCLUSIONS: The niacin-induced skin flushing was prevalently blunted in patients with schizophrenia or affective disorders, indicating a promising potential as an auxiliary diagnostic marker in risk prediction and clinical management of these disorders. Additionally, the niacin-blunted subgroup implies a common biological basis in the investigated disorders, which provokes new thoughts in elucidating the pathological mechanisms.

Serum Metabolomic Profiling Based on Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry: Do the Dysfunctions of Metabolic Pathways Reveal a Universal Risk of Oxidative Stress in Schizophrenia?

Schizophrenia is a chronic, disabling, and complex mental illness, of which the pathogenesis remains elusive. To provide clues for the pathogenesis and etiology of schizophrenia, we performed serum metabolic profiling in 54 patients with schizophrenia and 54 matched healthy controls using Fourier transform-ion cyclotron resonance-mass spectrometry. Based on 94 differential metabolites identified, we discovered two dysregulated metabolic pathways in schizophrenia, including the upregulated arachidonic acid-related pathway and the downregulated aromatic amino acid-related pathway. Moreover, carnitine was identified as a promising diagnostic biomarker for schizophrenia with an area under the curve of 0.997. Given the antioxidant and pro-oxidant properties of these altered metabolites, these results pointed to an imbalance of the redox homeostasis in schizophrenia, which was further confirmed by a remarkable elevation of 8-hydroxydeoxyguanosine (8-OHdG), a reactive oxidative stress marker. Furthermore, correlation analyses demonstrated that 8-OHdG was negatively correlated with antioxidant biliverdin and positively related to oxidation products, 9-hydroxylinoleic acid and o-tyrosine, and that total antioxidant capacity was positively associated with antioxidant acetylcarnitine in schizophrenia. Our results lead to the hypothesis that the disturbed metabolic characteristics reveal enhanced oxidative stress, which in turn results in the damage of lipids, proteins, and DNA and ultimately promotes the development of schizophrenia.

An investigation of calcium-independent phospholipase A2 (iPLA2) and cytosolic phospholipase A2 (cPLA2) in schizophrenia.

Evidence indicates that abnormal phospholipase A2 (PLA2) levels and niacin insensitivity are present in individuals with schizophrenia. This study was designed to determine whether differences in plasma calcium-independent phospholipase A2 (iPLA2) and cytosolic phospholipase A2 (cPLA2) exist between those with schizophrenia and healthy controls, and to explore the correlation between PLA2s and the niacin skin reaction in schizophrenic patients. We performed ELISA experiments to measure the concentrations of plasma iPLA2 and cPLA2 and we conducted a series of niacin skin tests on schizophrenic patients from the Chinese Han population. In addition, a meta-analysis of the relationship between PLA2 and schizophrenia was conducted. The plasma concentration of iPLA2 in patients with schizophrenia was significantly higher than that in healthy controls while the plasma concentration of cPLA2 did not differ. The meta-analysis also revealed that the activity level of iPLA2 in individuals with schizophrenia was higher than that in healthy controls, whereas that of cPLA2 was not. Furthermore, a significant positive correlation was found between the concentration of iPLA2 and the score for the skin flushing response within 20 min. The abnormal plasma iPLA2 concentration and its relationship with the niacin skin test in schizophrenic patients has contributed to a deeper understanding of the pathology of schizophrenia, which may in turn provide new insights into the clinical diagnoses and treatment of schizophrenia.