Complementary immunoregulatory effects of Bifidobacterium longum 1714TM associated exopolysaccharide and tryptophan metabolism

Distress Intolerance, Kynurenic Acid, and Schizophrenia

Inhibition of Dendritic Cell Differentiation by Fumaric Acid Esters

Kynurenic acid (KYNA), an endogenous neuroprotectant with antiexcitotoxic, antioxidant, and anti-inflammatory effects, is synthesized through the tryptophan-kynurenine (KYN) pathway. We investigated whether brain KYN or KYNA levels were affected by asphyxia in a translational piglet model of hypoxic–ischemic encephalopathy (HIE). We also studied brain levels of the putative blood–brain barrier (BBB) permeable neuroprotective KYNA analogue SZR72, and whether SZR72 or therapeutic hypothermia (TH) modified KYN or KYNA levels. KYN, KYNA, and SZR72 levels were determined using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry in five brain regions 24 h after 20 min of asphyxia in vehicle-, SZR72- and TH-treated newborn piglets (n = 6-6-6) and naive controls (n = 4). Endogenous brain KYN levels (median range 311.2–965.6 pmol/g) exceeded KYNA concentrations (4.5–6.0 pmol/g) ~100-fold. Asphyxia significantly increased cerebral KYN and KYNA levels in all regions (1512.0–3273.9 and 16.9–21.2 pmol/g, respectively), increasing the KYN/Tryptophan-, but retaining the KYNA/KYN ratio. SZR72 treatment resulted in very high cerebral SZR72 levels (13.2–33.2 nmol/g); however, KYN and KYNA levels remained similar to those of the vehicle-treated animals. However, TH virtually ameliorated asphyxia-induced elevations in brain KYN and KYNA levels. The present study reports for the first time that the KYN pathway is altered during HIE development in the piglet. SZR72 readily crosses the BBB in piglets but fails to affect cerebral KYNA levels. Beneficial effects of TH may include restoration of the tryptophan metabolism to pre-asphyxia levels.

IntroductionThe kynurenine pathway of tryptophan catabolism has come into the spotlight of schizophrenia research since its catabolites exert neuroactive effects. A strong body of evidence suggests that kynurenic acid, a catabolite of kynurenine pathway, acts as the only endogenous NMDA receptor antagonist leading to the weakening of circuits in layer III of dorsolateral prefrontal cortex of schizophrenia patients. Studies exploring the levels of kynurenic acid and other metabolites of tryptophan in peripheral blood did not yield any definite conclusions.ObjectivesPrimary objective of this study was to assess differences in concentrations of key constituents of kynurenic pathway in blood plasma – tryptophan (TRP), kynurenine (KYN) and kynurenic acid (KYNA) between schizophrenia patients (SCZ) and healthy controls (HC). Secondary objective was to explore correlations between these concentrations and clinical characteristics.MethodsIn our two-centre prospective case-control study we measured plasma concentrations of TRP, KYN and KYNA in 36 healthy controls (HC) and 38 schizophrenia (SCZ) patients during acute exacerbation and remission and explored the correlations with clinical parameters using PANSS scale. The patients were matched with HC by age, sex and body mass index and exclusion criteria included obesity class 2 or higher, any concomitant organic mental or neurological disorder, acute or chronic inflammatory disease, and use of immunomodulatory drugs or psychoactive substances.ResultsTRP concentrations were significantly higher in HC than in SCZ patients in acute phase (p<0,001) and remission (p<0,001), while SCZ patients in acute phase had significantly higher TRP levels than in remission (p<0,01). Levels of KYNA and KYN were significantly lower in SCZ patients than in HC both in acute phase and remission, all with high statistical significance (p<0,001). There was no statistically significant difference between acute phase and remission neither for KYN (p>0,05), nor for KYNA (p>0,05). There was no correlation of plasma levels of TRP, KYN and KYNA with total PANSS score, PANSS positive scale score, PANSS negative scale score and PANSS general psychopathology scores, both in acute phase and remission (p>0,05). Also, there was no correlation between plasma levels of TRP, KYN and KYNA in SCZ patients in remission with improvements measured with PANSS scale (p>0,05).ConclusionsAlthough there are concerns about the value of measurement of metabolites of kynurenine pathway in the peripheral blood, our data suggest that significantly decreased levels of KYN and KYNA could suggest that disrupted TRP degradation in SCZ patients may be reflected in the peripheral blood as well. Further studies of peripheral levels of kynurenine pathway metabolites on larger samples should also explore effects of antipsychotic therapy, but also their correlation with other clinical parameters such as neurocognition.Disclosure of InterestNone Declared

Enhanced TARC production by dust-mite allergens and its modulation by immunosuppressive drugs in PBMCs from patients with atopic dermatitis

Normal pressure hydrocephalus (NPH) is a potentially reversible neurological syndrome commonly characterized by gait disturbance, urinary incontinence, and dementia. Hydrocephalus e-vacuo (He-v) is also characterized by the occurrence of dementia but does not show gait disturbance or urinary incontinence and has no evident cerebrospinal fluid (CSF) pressure elevation. Kynurenic acid (KYNA), an endogenous metabolite of the L-kynurenine (L-KYN) pathway of L-tryptophan (L-TRP) degradation, is an antagonist of glutamate N-methyl-D-aspartic acid and alpha-7 nicotinic cholinergic receptors that have been linked to dementia. We investigated KYNA, L-KYN, and L-TRP levels in human CSF and serum during the aging process in 30 healthy control individuals. In addition, clinical parameters and L-TRP metabolites in CSF and serum were evaluated in four patients with NPH and five with He-v. KYNA, L-KYN, and L-TRP levels in CSF and serum were determined using highperformance liquid chromatography. Healthy controls showed a significant decrease in serum albumin with age. Compared with their corresponding controls and unlike patients with He-v, patients with NPH (age ≤ 50 years) had significant increases in CSF protein (241%, p < 0.001), CSF albumin (246%, p < 0.001), CSF IgG (328%, p < 0.001), and CSF:serum IgG (321%, p < 0.001) and CSF:serum albumin (257%, p < 0.001) ratios. Controls had significant increases in KYNA, L-KYN, and L-TRP levels in the CSF with advancing age but not in the serum. Compared with the corresponding controls, KYNA levels were significantly increased in the CSF of patients with NPH (141%, p < 0.05) and He-v (225%; p < 0.01). Additionally, the serum levels of KYNA were increased in patients with NPH and He-v to 161% and 156% of controls, respectively (both p < 0.01). The serum levels of L-KYN and L-TRP were significantly reduced in patients with He-v but not in patients with NPH. C-reactive protein, as a marker of inflammation, was significantly increased in the serum of patients with He-v but not in patients with NPH, compared with the corresponding controls. The aging process is related to elevated CSF levels of KYNA, L-KYN, and L-TRP levels. There are significant differences in clinical parameters between the two forms of hydrocephalus and these differences might have diagnostic utility. The occurrence of dementia in patients with either form of hydrocephalus might be at least partly related to elevated KYNA levels in the CNS and/or periphery.

Patients with schizophrenia show elevated brain levels of the neuroactive tryptophan metabolite kynurenic acid (KYNA). This astrocyte-derived mediator acts as a neuroprotectant and modulates sensory gating and cognitive function. We measured the levels of KYNA in the cerebrospinal fluid (CSF) of patients with bipolar disorder and healthy volunteers to investigate the putative involvement of KYNA in bipolar disorder. We obtained CSF by lumbar puncture from 23 healthy men and 31 euthymic men with bipolar disorder. We analyzed the samples using high-performance liquid chromatography. Patients with bipolar disorder had increased levels of KYNA in their CSF compared with healthy volunteers (1.71 nM, standard error of the mean [SEM] 0.13 v. 1.13 nM, SEM 0.09; p = 0.002. The levels of KYNA were positively correlated with age among bipolar patients but not healthy volunteers. The influence of ongoing drug treatment among patients cannot be ruled out. We conducted our study during the euthymic phase of the disease. Brain KYNA levels are increased in euthymic men with bipolar disorder. In addition, KYNA levels increased with age in these patients. These findings indicate shared mechanisms between bipolar disorder and schizophrenia. Elevated levels of brain KYNA may provide further insight to the pathophysiology and progression of bipolar disorder.

Background: Patients with schizophrenia show elevated brain levels of the neuroactive tryptophan metabolite kynurenic acid (KYNA). This astrocyte-derived mediator acts as a neuroprotectant and modulates sensory gating and cognitive function. We measured the levels of KYNA in the cerebrospinal fluid (CSF) of patients with bipolar disorder and healthy volunteers to investigate the putative involvement of KYNA in bipolar disorder. Methods: We obtained CSF by lumbar puncture from 23 healthy men and 31 euthymic men with bipolar disorder. We analyzed the samples using high-performance liquid chromatography. Results: Patients with bipolar disorder had increased levels of KYNA in their CSF compared with healthy volunteers (1.71 nM, standard error of the mean [SEM] 0.13 v. 1.13 nM, SEM 0.09; p = 0.002. The levels of KYNA were positively correlated with age among bipolar patients but not healthy volunteers. Limitations: The influence of ongoing drug treatment among patients cannot be ruled out. We conducted our study during the euthymic phase of the disease. Conclusion: Brain KYNA levels are increased in euthymic men with bipolar disorder. In addition, KYNA levels increased with age in these patients. These findings indicate shared mechanisms between bipolar disorder and schizophrenia. Elevated levels of brain KYNA may provide further insight to the pathophysiology and progression of bipolar disorder.

BackgroundIntestinal homoeostasis is dependent on immunological tolerance to the microbiota.ObjectiveTo (1) determine if a probiotic could induce Foxp3 T cells in humans; (2) to elucidate the molecular mechanisms, which are...

Objective To induce monocyte-derived dendritic cells (MoDC) from acute myeloid leukemia (AML) and healthy persons by rhCD40L in normal human AB serum system in vitro and to identify the morphology and phenotype of MoDC. Methods Peripheral blood mononuclear cells (PBMNC) of AML and healthy persons were cultured in RPMI 1640 media including human AB serum, GM-CSF, rhIL-4 and rhCD40L, respectively. MoDC were identified by morphological features, surface antigen expression and the ability to stimulate T cells. Results After cultured for 7 days, MoDC displayed typical morphology with elongated dendritic process,and upregulation of the costimulatory molecules CD40,CD80,CD86 and CD83.The morphology and expression of costimulatory molecules were not significantly different between AML and healthy persons (P＞0.05),but were significantly different between rhCD40L group and without rhCD40L group (P＜0.05). MoDC had the ability to activate T cells, and there were no statistical differences between AML and healthy persons (P ＞0.05), but were significant differences between rhCD40L group and without rhCD40L group (P＜0.05). MoDC started to secrete IL-12 on day 5, and there was no statistical differences between AML and healthy persons(P＞0.05),and had differences between rhCD40L group and without rhCD40L group (P＜0.05).Conclusion MoDC can be cultured from the peripheral blood of AML and healthy persons.There were no significant differences in morphology and phenotype.Monocyted-derived DC can be used as an alternative to generate leukemia-specific cytotoxic T cells,especially in the presence of rhCD40L. Key words: Dendritic cells; Leukemia,myeloid,acute; rhCD40L

Toxoplasma gondii and Schizophrenia: Linkage Through Astrocyte-Derived Kynurenic Acid?

Caffeic Acid Phenethyl Ester Possessing Various Immunomodulatory Effects Is a Potentially Effective Therapy for Asthma

A sensitive UPLC-MS/MS method for the simultaneous determination of the metabolites in the tryptophan pathway in rat plasma

Objective To investigate the frequencies of circulating dendritic cell (DC) subsets and the function of monocyte-derived dendritic cells in patients with hepatitis B-related acute-on-chronic liver failure. Methods Peripheral blood was collected from hepatitis B-related acute-on-chronic liver failure patients (ACLF, n=40) and chronic hepatitis B (CHB, n=40) as well as normal controls (NCs, n=20). Circulating myeloid dendritic cell (Mdc) and plasmic dendritic cell (pDC) frequencies in peripheral blood mononuclear cells (PBMC) were analyzed by flow cytometric analysis. Purified monocytes were isolated by combination of Histopaque-1.077 and CD14 Microbeads. Monocyte-derived dendritic cells (MoDCs) generated in vitro in the presence of interleukin (IL)-4 and granulocyte macrophage colony-stimulating factor upon activation by poly I∶C. Costimulatory molecule expression and allostimulatory mixed lymphocyte reaction (AMLR) of MoDCs were detected in patients with hepatitis B-related ACLF. Results The number of circulating mDC decreased only in patients with hepatitis B-related ACLF compared with that in normal controls. However, pDC numbers decreased in both CHB and ACLF patients. We observed a further decrease the pDC numbers in ACLF compared to CHB patients without statistical significance (P>0.05). MoDC from ACLF patients showed lower expression of costimulatory molecules CD80, CD86 and the mature marker CD83, as well as MHC Ⅱ molecule (HLA-DR) compared to CHB and NC group. Interestingly, MoDC impaired allostimulatory mixed lymphocyte reaction from ACLF patients compared to those in CHB patients and NCs. Conclusions Patients with hepatitis B-related ACLF have a significantly lower expression of surface markers and impaired AMLR of MoDC, as well as decreased number of circulating mDC and pDC, which may be partially related to HBV disease progression in these patients. Key words: Liver failure, acute/ME; Dendritic cells/ME

Background:Complex interaction of genetic defects with environmental factors seems to play a substantial role in the pathogenesis of inflammatory bowel disease (IBD). Accumulating data implicate a potential role of disturbed tryptophan metabolism in IBD. Kynurenic acid (KYNA), a derivative of tryptophan (TRP) along the kynurenine (KYN) pathway, displays cytoprotective and immunomodulating properties, whereas 3-OH-KYN is a cytotoxic compound, generating free radicals.Methods:The expression of lymphocytic mRNA encoding enzymes synthesizing KYNA (KAT I–III) and serum levels of TRP and its metabolites were evaluated in 55 patients with IBD, during remission or relapse [27 patients with ulcerative colitis (UC) and 28 patients with Crohn’s disease (CD)] and in 50 control individuals.Results:The increased expression of KAT1 and KAT3 mRNA characterized the entire cohorts of patients with UC and CD, as well as relapse–remission subsets. Expression of KAT2 mRNA was enhanced in patients with UC and in patients with CD in remission. In the entire cohorts of UC or CD, TRP levels were lower, whereas KYN, KYNA and 3-OH-KYN were not altered. When analysed in subsets of patients with UC and CD (active phase–remission), KYNA level was significantly lower during remission than relapse, yet not versus control. Functionally, in the whole groups of patients with UC or CD, the TRP/KYN ratio has been lower than control, whereas KYN/KYNA and KYNA/3-OH-KYN ratios were not altered. The ratio KYN/3-OH-KYN increased approximately two-fold among all patients with CD; furthermore, patients with CD with relapse, manifested a significantly higher KYNA/3-OH-KYN ratio than patients in remission.Conclusion:The presented data indicate that IBD is associated with an enhanced expression of genes encoding KYNA biosynthetic enzymes in lymphocytes; however, additional mechanisms appear to influence KYNA levels. Higher metabolic conversion of serum TRP in IBD seems to be followed by the functional shift of KYN pathway towards the arm producing KYNA during exacerbation. We propose that KYNA, possibly via interaction with aryl hydrocarbon receptor or G-protein-coupled orphan receptor 35, may serve as a counter-regulatory mechanism, decreasing cytotoxicity and inflammation in IBD. Further longitudinal studies evaluating the individual dynamics of TRP and KYN pathway in patients with IBD, as well as the nature of precise mechanisms regulating KYNA synthesis, should be helpful in better understanding the processes underlying the observed changes.