Exploring low grade inflammation by soluble urokinase plasminogen activator receptor levels in schizophrenia: a sex-dependent association with depressive symptoms.

BACKGROUND: There is evidence of increased low grade inflammation (LGI) in schizophrenia patients. However, the inter-individual variation is large and the association with demographic, somatic and psychiatric factors remains unclear. Our aim was to explore whether levels of the novel LGI marker soluble urokinase plasminogen activator receptor (suPAR) were associated with clinical factors in schizophrenia and if such associations were sex-dependent. METHOD: In this observational study a total of 187 participants with schizophrenia (108 males, 79 females) underwent physical examination and assessment with clinical interviews (Positive and Negative Syndrome Scale (PANSS), Calgary Depression Scale for Schizophrenia (CDSS), Alcohol Use Disorder Identification Test (AUDIT), and Drug Use Disorder Identification Test (DUDIT)). Blood levels of suPAR, glucose, lipids, and high sensitivity C-reactive protein (hsCRP) were determined and body mass index (BMI) calculated. Multivariable linear regression analyses were used adjusting for confounders, and sex interaction tested in significant variables. RESULTS: Adjusting for sex, age, current tobacco smoking and BMI, we found that levels of hsCRP and depressive symptoms (CDSS) were positively associated with levels of suPAR (p < 0.001). The association between suPAR and CDSS score was significant in females (p < 0.001) but not in males. Immune activation measured by hsCRP was not associated with depressive symptoms after adjusting for BMI. CONCLUSION: Our findings indicate that increased suPAR levels are associated with depressive symptoms in females with schizophrenia, suggesting aberrant immune activation in this subgroup. Our results warrant further studies, including longitudinal follow-up of suPAR levels in schizophrenia and experimental studies of mechanisms.

Diabetic ketoacidosis and diabetes associated with antipsychotic exposure among a previously diabetes-naive population with schizophrenia: a nationwide nested case-control study.

AIMS/HYPOTHESIS: Diabetic ketoacidosis (DKA) is a potentially fatal metabolic emergency of both type 1 and type 2 diabetes. Although there is a reduced risk of type 1 diabetes in schizophrenia, the incidence of DKA is tenfold higher than that of the general population. Thus, we aimed to investigate associations between exposure to antipsychotic medication (within 3 months prior to event) and DKA, type 1 diabetes and type 2 diabetes. We also reported related, clinically relevant outcomes. METHODS: Using a nested case-control study design, we identified cases of DKA, type 1 diabetes and type 2 diabetes in a previously diabetes-naive population with schizophrenia in Denmark from 1995 to 2014. Cases were matched (by age, sex and year of schizophrenia onset) 1:5 to schizophrenic control individuals who were alive and had not emigrated prior to event. Conditional logistic regression was used to compute ORs with 95% CIs. Other outcomes included diabetes aetiology of DKA, in-hospital mortality, DKA readmissions and temporal trends of use of insulin and oral glucose-lowering agents. RESULTS: Of 29,955 individuals with schizophrenia, we identified 28 individuals with DKA, 90 with type 1 diabetes and 2140 with type 2 diabetes. These were matched to 137, 410 and 9861 individuals in the control group, respectively. Antipsychotic exposure was associated with DKA (OR 2.60; 95% CI 1.06, 6.38) and type 2 diabetes (OR 1.64; 95% CI 1.48, 1.83). A trend towards increased risk of type 1 diabetes was found but remained insignificant (OR 1.38; 95% CI 0.84, 2.29). Diabetes aetiology of DKA was type 1 in eight cases and type 2 in 14 cases. Of the remaining six cases of DKA, aetiology could not be determined, as four were fatal within 8 days and for two, no prescriptions for insulin and oral glucose-lowering agents were redeemed. Of all DKA cases, six had more than one episode of DKA, and of all type 1 diabetes and type 2 diabetes cases, four and 11, respectively, had at least one episode. Use of insulin and oral glucose-lowering agents was higher among individuals with DKA relative to those with type 1 diabetes and type 2 diabetes. CONCLUSIONS/INTERPRETATION: Antipsychotic exposure was associated with DKA and type 2 diabetes in a previously diabetes-naive schizophrenia population. Antipsychotic-associated DKA is relevant not only for psychiatrists but also for other physicians who may manage and admit such patients.

Antipsychotic-associated psoriatic rash - a case report.

BACKGROUND: Antipsychotics are a heterogeneous group of drugs. Although, antipsychotics have been used for years, unexpected side effects may still occur. With this case report we focus on a possible association between psoriasis and antipsychotics. Data on the patient's course of psychiatric disease, onset of psoriasis and its evolution were extracted from the patient's medical files. CASE PRESENTATION: We present a case of a 21-year-old female diagnosed with schizophrenia. She was initially treated with quetiapine, and later switched to aripiprazole due to weight gain. After initiation of antipsychotic treatment, the patient suffered from severe psoriasis lesions. CONCLUSIONS: Antipsychotics may possess immunological properties that may be involved in immune-mediated conditions, such as psoriatic rash. Further studies are warranted to determine causality and mechanism.

Eosinophilic myocarditis during treatment with olanzapine - report of two possible cases.

BACKGROUND: Drug-induced eosinophilic myocarditis is a life-threatening and frequently overlooked condition. The prevalence of myocarditis in clozapine-treated patients may be as high as 3 %. An association between olanzapine and myocarditis has not previously been described, but given the chemical similarity between olanzapine and clozapine, we hypothesized the existence of such an association. We searched the spontaneous adverse drug reports database of the Danish Health and Medicines Authority for olanzapine and myocarditis in the period from October 21, 1996 to - June 03, 2015. We identified two fatal cases of eosinophilic myocarditis associated with the use of olanzapine. CASE PRESENTATION: Case 1 was a 39-year-old Caucasian man with known substance abuse and schizophrenia. He was found dead in his home. Olanzapine was prescribed at day -54, and dose at time of death was 40 mg/day. Post-mortem toxicological examination demonstrated presence of olanzapine, morphine, venlafaxine and oxazepam. Syringes indicating substance abuse were found in his home. Case 2 was a 36-year-old Caucasian man diagnosed with schizophrenia was found dead unexpectedly. There was no history of substance abuse. Current treatment was olanzapine 20 mg/day +5 mg as PRN (prescribed for almost 4 years), aripiprazole 30 mg/day (prescribed for 6 months) and mirtazapine 30 mg/day (prescribed for 6 months). Both cases of eosinophilic myocarditis were confirmed by autopsy findings and both patients received olanzapine in doses exceeding the recommendations. CONCLUSION: Olanzapine may have contributed to and/or worsened the two reported fatal cases of myocarditis. Additional studies are required to establish a causal link between olanzapine and eosinophilic myocarditis.

Protein tyrosine phosphatases and the immune response.

Reversible tyrosine phosphorylation of proteins is a key regulatory mechanism for numerous important aspects of eukaryotic physiology and is catalysed by kinases and phosphatases. Together, cells of the immune system express at least half of the 107 protein tyrosine phosphatase (PTP) genes in the human genome, most of which encode multidomain proteins that contain protein- and phospholipid-interaction domains. Here, we discuss the diverse but specific, and important, roles that PTPs have in immune cells, focusing mainly on T and B cells, and we highlight recent evidence that even subtle alterations in PTPs can cause immune dysfunction and human disease.

LYP inhibits T-cell activation when dissociated from CSK.

Lymphoid tyrosine phosphatase (LYP) and C-terminal Src kinase (CSK) are negative regulators of signaling mediated through the T-cell antigen receptor (TCR) and are thought to act in a cooperative manner when forming a complex. Here we studied the spatiotemporal dynamics of the LYP-CSK complex in T cells. We demonstrate that dissociation of this complex is necessary for recruitment of LYP to the plasma membrane, where it downmodulates TCR signaling. Development of a potent and selective chemical probe of LYP confirmed that LYP inhibits T-cell activation when removed from CSK. Our findings may explain the reduced TCR-mediated signaling associated with a single-nucleotide polymorphism that confers increased risk for certain autoimmune diseases, including type 1 diabetes and rheumatoid arthritis, and results in expression of a mutant LYP that is unable to bind CSK. Our compound also represents a starting point for the development of a LYP-based treatment of autoimmunity.

Autoimmune-associated lymphoid tyrosine phosphatase is a gain-of-function variant.

A SNP in the gene PTPN22 is associated with type 1 diabetes, rheumatoid arthritis, lupus, Graves thyroiditis, Addison disease and other autoimmune disorders. T cells from carriers of the predisposing allele produce less interleukin-2 upon TCR stimulation, and the encoded phosphatase has higher catalytic activity and is a more potent negative regulator of T lymphocyte activation. We conclude that the autoimmune-predisposing allele is a gain-of-function mutant.

T cell-signaling network analysis reveals distinct differences between CD28 and CD2 costimulation responses in various subsets and in the MAPK pathway between resting and activated regulatory T cells.

To uncover signaling system differences between T cell stimuli and T cell subsets, phosphorylation status of 18 signaling proteins at six different time points following TCR triggering and CD28/CD2 costimulation was examined in human T cell subsets by phospho-epitope-specific flow cytometry of fluorescent cell barcoded samples, thereby providing a high-resolution signaling map. Compared with effector/memory T cells, naive T cells displayed stronger activation of proximal signaling molecules after TCR triggering alone. Conversely, distal phosphorylation events, like pErk and pS6-ribosomal protein, were stronger in effector/memory subsets. CD28 costimulation specifically induced signaling necessary for proper NF-κB activation, whereas CD2 signaled more strongly to S6-ribosomal protein. Analysis of resting regulatory T cells (rTregs; CD4(+)CD45RA(+)FOXP3(+)) and activated regulatory T cells (actTregs; CD4(+)CD45RA(-)FOXP3(++)) revealed that, although rTregs had low basal, but inducible, Erk activity, actTregs displayed high basal Erk phosphorylation and little or no Akt activation. Interestingly, the use of Mek inhibitors to block Erk activation inhibited activation-dependent FOXP3 upregulation in rTregs, their transition to actTregs, and the resulting increase in suppressive capacity. In summary, our systems approach unraveled distinct differences in signaling elicited by CD28 and CD2 costimulation and between rTregs and actTregs. Blocking rTreg transition to highly suppressive actTregs by Mek inhibitors might have future therapeutic applications.

Alterations in inflammatory markers after a 12-week exercise program in individuals with schizophrenia-a randomized controlled trial.

Background: In individuals with schizophrenia, inflammation is associated with depression, somatic comorbidity and reduced quality of life. Physical exercise is known to reduce inflammation in other populations, but we have only limited knowledge in the field of schizophrenia. We assessed inflammatory markers in plasma samples from individuals with schizophrenia participating in an exercise intervention randomized controlled trial. We hypothesized that (i) physical exercise would reduce levels of inflammatory markers and (ii) elevated inflammatory status at baseline would be associated with improvement in cardiorespiratory fitness (CRF) following intervention. Method: Eighty-two individuals with schizophrenia were randomized to a 12-week intervention of either high-intensity interval training (HIIT, n = 43) or active video gaming (AVG, n = 39). Participants were assessed at baseline, post intervention and four months later. The associations between exercise and the inflammatory markers soluble urokinase plasminogen activator receptor, c-reactive protein, tumor necrosis factor (TNF), soluble TNF receptor 1 and interleukin 6 (IL-6) were estimated using linear mixed effect models for repeated measures. For estimating associations between baseline inflammation and change in CRF, we used linear regression models. Results: Our main findings were (i) TNF and IL-6 increased during the intervention period for both groups. Other inflammatory markers did not change during the exercise intervention period; (ii) baseline inflammatory status did not influence change in CRF during intervention, except for a positive association between baseline IL-6 levels and improvements of CRF to post intervention for both groups. Conclusion: In our study, HIIT and AVG for 12-weeks had no reducing effect on inflammatory markers. Patients with high baseline IL-6 levels had a positive change in CRF during intervention. In order to increase our knowledge regarding association between inflammatory markers and exercise in individuals with schizophrenia, larger studies with more frequent and longer exercise bout duration are warranted.

TCR-induced downregulation of protein tyrosine phosphatase PEST augments secondary T cell responses.

We report that the protein tyrosine phosphatase PTP-PEST is expressed in resting human and mouse CD4(+) and CD8(+) T cells, but not in Jurkat T leukemia cells, and that PTP-PEST protein, but not mRNA, was dramatically downregulated in CD4(+) and CD8(+) primary human T cells upon T cell activation. This was also true in mouse CD4(+) T cells, but less striking in mouse CD8(+) T cells. PTP-PEST reintroduced into Jurkat at levels similar to those in primary human T cells, was a potent inhibitor of TCR-induced transactivation of reporter genes driven by NFAT/AP-1 and NF-kappaB elements and by the entire IL-2 gene promoter. Introduction of PTP-PEST into previously activated primary human T cells also reduced subsequent IL-2 production by these cells in response to TCR and CD28 stimulation. The inhibitory effect of PTP-PEST was associated with dephosphorylation the Lck kinase at its activation loop site (Y394), reduced early TCR-induced tyrosine phosphorylation, reduced ZAP-70 phosphorylation and inhibition of MAP kinase activation. We propose that PTP-PEST tempers T cell activation by dephosphorylating TCR-proximal signaling molecules, such as Lck, and that down-regulation of PTP-PEST may be a reason for the increased response to TCR triggering of previously activated T cells.

Removal of C-terminal SRC kinase from the immune synapse by a new binding protein.

The Csk tyrosine kinase negatively regulates the Src family kinases Lck and Fyn in T cells. Engagement of the T-cell antigen receptor results in a removal of Csk from the lipid raft-associated transmembrane protein PAG/Cbp. Instead, Csk becomes associated with an approximately 72-kDa tyrosine-phosphorylated protein, which we identify here as G3BP, a phosphoprotein reported to bind the SH3 domain of Ras GTPase-activating protein. G3BP reduced the ability of Csk to phosphorylate Lck at Y505 by decreasing the amount of Csk in lipid rafts. As a consequence, G3BP augmented T-cell activation as measured by interleukin-2 gene activation. Conversely, elimination of endogenous G3BP by RNA interference increased Lck Y505 phosphorylation and reduced TCR signaling. In antigen-specific T cells, endogenous G3BP moved into a intracellular location adjacent to the immune synapse, but deeper inside the cell, upon antigen recognition. Csk colocalization with G3BP occurred in this "parasynaptic" location. We conclude that G3BP is a new player in T-cell-antigen receptor signaling and acts to reduce the amount of Csk in the immune synapse.

A switch-variant model integrates the functions of an autoimmune variant of the phosphatase PTPN22.

The R620W polymorphism in protein tyrosine phosphatase nonreceptor type 22 (PTPN22) predisposes carriers to several autoimmune diseases. Two papers in Science Immunology and Science Signaling on this human disease-associated variant lead us to propose a new "switch-of-function" model.

Effect of a physical activity intervention on suPAR levels: A randomized controlled trial.

OBJECTIVES: Soluble urokinase-type plasminogen activator receptor (suPAR) is a novel inflammatory marker, associated with lifestyle diseases and mortality risk. No studies have investigated whether physical activity may reduce suPAR levels using a randomized controlled design. DESIGN AND METHODS: suPAR and C-reactive protein (CRP) levels were determined in blood samples from a previous randomized controlled trial with Pakistani immigrants in Norway, 2008. The study included physically inactive men that were randomized to an intervention group (supervised group exercises) or a control group and followed for 5 months. A linear regression model was used and adjusted for age, inactivity level at baseline, and mean difference in CRP levels. RESULTS: Overall, 80 and 53 participants were included in the intervention and control group, respectively. Obesity and smoking were associated with higher suPAR levels at baseline. The intervention group had a mean suPAR level of 2.65 (95% CI=2.48-2.78)ng/mL at baseline compared to 2.80 (95% CI=2.65-2.95)ng/mL at post-test, and thereby significantly increased suPAR levels after intervention (p=0.02). In the control group, mean suPAR level significantly increased from 2.93 (95% CI=2.68-3.16)ng/mL at baseline to 3.09 (95% CI=2.81-3.38)ng/mL at post-test (p=0.04). When comparing change from baseline to post-test in suPAR levels for the intervention group versus the control group, no significant change in the unadjusted model was found (ß=-0.002, 95% CI=-0.219-0.215). Similar results were found for CRP levels. CONCLUSION: There was no change in suPAR levels after regular exercise compared to a control group implying that suPAR rather reflects underlying harmful inflammatory responses associated with disease development.

Protein tyrosine phosphatase PTPN22 in human autoimmunity.

The discovery that a single-nucleotide polymorphism (SNP) in lymphoid tyrosine phosphatase (LYP), encoded by the PTPN22 gene, is associated with type 1 diabetes (T1D) has now been verified by numerous studies and has been expanded to rheumatoid arthritis, juvenile rheumatoid arthritis (JRA), systemic lupus erythematosus, Graves' disease, generalized vitiligo and other human autoimmune diseases. In this paper, we discuss the association of PTPN22 with autoimmunity, the biochemistry of the PTPN22-encoded phosphatase, and the molecular mechanism(s) by which the disease-predisposing allele contributes to the development of human disease.

Diabetic ketoacidosis in patients exposed to antipsychotics: a systematic literature review and analysis of Danish adverse drug event reports.

RATIONALE: Patients exposed to second-generation antipsychotics (SGAs) have approximately 10 times increased risk of diabetic ketoacidosis (DKA) compared with the general population. However, as DKA is a rare complication of type 2 diabetes mellitus, and susceptible patients exposed to antipsychotics may rapidly develop DKA independently of treatment duration and weight gain, this is rather suggestive of type 1 diabetes mellitus (T1DM) or latent autoimmune diabetes in adults. OBJECTIVES: We performed a systematic review of current studies regarding antipsychotic-associated DKA with type 1 etiology and analyzed Danish adverse drug event (ADE) reports (previously unpublished cases). METHODS: PubMed, Embase, and the Cochrane Library were searched for all relevant studies, and the Danish Medicines Agency retrieved ADE reports using the Danish ADE database (up to date as of June 28, 2016). Diagnosis of antipsychotic-associated DKA with type 1 etiology was either considered confirmed or possible depending on authors' conclusions in the studies and/or clinical aspects. In addition, clinico-demographic risk factors were extracted. RESULTS: A total of 655 records and 11 ADE reports were identified, and after screening for eligibility, we included 21 case reports/series and two ADE reports (n = 24). No relevant clinical studies were included. Although fatal cases were identified, these were excluded because of diagnostic uncertainties (n = 15). DKA occurred in 15 males (62.5 %) and nine females (37.5 %), with a mean age ± standard deviation of 34.8 ± 12.4 years. Median time to DKA was 5 months (interquartile range: 1.4-11 months). Associated antipsychotics were olanzapine (n = 9, 36 %), aripiprazole (n = 6, 24 %), risperidone (n = 6, 24 %), clozapine (n = 3, 12 %), and quetiapine (n = 1, 4 %). Nine patients (37.5 %) were confirmedly diagnosed with T1DM following DKA resolution, whereas 15 patients (62.5 %) had possible T1DM. In 22 patients (91.7 %), ongoing insulin treatment was required for glycemic control. CONCLUSIONS: Increased awareness of the potential risk of antipsychotic-associated DKA and subsequent T1DM diagnosis, with insulin requirements for glycemic control, is warranted. The underlying mechanisms are poorly understood but most probably multifactorial. Certainly, further studies are warranted. Clinicians must utilize appropriate monitoring in susceptible patients and consider the possibility of continuing antipsychotic treatment with appropriate diabetic care.

Molecular mechanisms for protein kinase A-mediated modulation of immune function.

Protein kinase A (PKA) is a serine/threonine kinase that regulates a number of cellular processes important for immune activation and control. Modulation of signal transduction by PKA is a complex and diverse process, and differential isozyme expression, holoenzyme composition and subcellular localization contribute specificity to the PKA signalling pathway. In lymphocytes, phosphorylation by PKA has been demonstrated to regulate antigen receptor-induced signalling both by altering protein-protein interactions and by changing the enzymatic activity of target proteins. PKA substrates involved in immune activation include transcription factors, members of the MAP kinase pathway and phospholipases. The ability of PKA type I to regulate activation of signalling components important for formation of the immunological synapse, demonstrates that the cAMP signalling pathway can directly modulate proximal events in lymphocyte activation. Furthermore, the recent discovery that PKA regulates Src kinases through modulation of Csk, supports the notion that PKA is involved in the fine-tuning of immune receptor signalling in lipid rafts.

Soluble urokinase-type plasminogen activator receptor levels in patients with schizophrenia.

BACKGROUND: The etiology of schizophrenia remains largely unknown but alterations in the immune system may be involved. In addition to the psychiatric symptoms, schizophrenia is also associated with up to 20 years reduction in life span. Soluble urokinase-type plasminogen activator receptor (suPAR) is a protein that can be measured in blood samples and reflects the levels of inflammatory activity. It has been associated with mortality and the development of type 2 diabetes and cardiovascular disease. METHODS: suPAR levels in patients with schizophrenia were compared to healthy controls from the Danish Blood Donor Study. SuPAR levels were dichotomized at >4.0 ng/ml, which is considered the threshold for low grade inflammation. A multiple logistic regression model was used and adjusted for age, sex, and current smoking. RESULTS: In total we included 1009 subjects, 105 cases with schizophrenia (10.4%) and 904 controls (89.6%). The mean suPAR values were 4.01 ng/ml (SD = 1.43) for the cases vs 1.91 ng/ml (SD = 1.35) for the controls (P < .001). Multiple logistic regression with odds ratio (OR) for suPAR levels >4.0 ng/ml yielded: schizophrenia, OR: 46.15 95% CI 22.69-93.87, P < .001; age, OR: 1.02 95% CI 0.99-1.02, P = .15; male sex, OR: 0.70 95% CI 0.35-1.36, P = .29; and current smoking, OR: 3.51 95% CI 1.78-6.94, P < .001. CONCLUSIONS: Patients with schizophrenia had significantly higher suPAR levels than healthy controls. Further studies are warranted to clarify if elevated suPAR levels are involved in the pathophysiology of schizophrenia and/or the increased mortality found in patients with schizophrenia.

The autoimmune-predisposing variant of lymphoid tyrosine phosphatase favors T helper 1 responses.

The C1858T single nucleotide polymorphism in PTPN22, which is the gene encoding lymphoid tyrosine phosphatase (LYP), confers increased risk for various autoimmune disorders in Caucasians. Although the disease-associated LYP allele (LYP*W620) is a gain-of-function variant that has higher catalytic activity than the major allele (LYP*R620), it is still unclear how LYP*W620 predisposes for autoimmunity. Here, we compared both T cell signaling and T cell function in healthy human donors homozygous for either LYP*R620 or LYP*W620. Generally, the presence of LYP*W620 caused reduced proximal T cell antigen receptor-mediated signaling (e.g. ζ chain phosphorylation) but augmented CD28-associated signaling (e.g. AKT activation). Altered ligand binding properties of the two LYP variants could explain these findings since LYP*R620 interacted more strongly with the p85 subunit of PI3K. Variation in signaling between cells expressing either LYP*R620 or LYP*W620 also affected the differentiation of conventional CD4(+) T cells. For example, LYP*W620 homozygous donors displayed exaggerated Th1 responses (e.g. IFNγ production) and reduced Th17 responses (e.g. IL-17 production). Importantly, while regulatory T cells normally suppressed Th1-mediated IFNγ production in LYP*R620 homozygous individuals, such suppression was lost in LYP*W620 homozygous individuals. Altogether, these findings provide a molecular and cellular explanation for the autoimmune phenotype associated with LYP*W620.

Inhibition of lymphoid tyrosine phosphatase by benzofuran salicylic acids.

The lymphoid tyrosine phosphatase (Lyp, PTPN22) is a critical negative regulator of T cell antigen receptor (TCR) signaling. A single-nucleotide polymorphism (SNP) in the ptpn22 gene correlates with the incidence of various autoimmune diseases, including type 1 diabetes, rheumatoid arthritis, and systemic lupus erythematosus. Since the disease-associated allele is a more potent inhibitor of TCR signaling, specific Lyp inhibitors may become valuable in treating autoimmunity. Using a structure-based approach, we synthesized a library of 34 compounds that inhibited Lyp with IC(50) values between 0.27 and 6.2 µM. A reporter assay was employed to screen for compounds that enhanced TCR signaling in cells, and several inhibitors displayed a dose-dependent, activating effect. Subsequent probing for Lyp's direct physiological targets by immunoblot analysis confirmed the ability of the compounds to inhibit Lyp in T cells. Selectivity profiling against closely related tyrosine phosphatases and in silico docking studies with the crystal structure of Lyp yielded valuable information for the design of Lyp-specific compounds.