Increased levels of 3-hydroxykynurenine parallel disease severity in human acute pancreatitis

Inhibition of kynurenine 3-monooxygenase (KMO) protects against multiple organ dysfunction (MODS) in experimental acute pancreatitis (AP). We aimed to precisely define the kynurenine pathway activation in relation to AP and AP-MODS in humans, by carrying out a prospective observational study of all persons presenting with a potential diagnosis of AP for 90 days. We sampled peripheral venous blood at 0, 3, 6, 12, 24, 48, 72 and 168 hours post-recruitment. We measured tryptophan metabolite concentrations and analysed these in the context of clinical data and disease severity indices, cytokine profiles and C-reactive protein (CRP) concentrations. 79 individuals were recruited (median age: 59.6 years; 47 males, 59.5%). 57 met the revised Atlanta definition of AP: 25 had mild, 23 moderate, and 9 severe AP. Plasma 3-hydroxykynurenine concentrations correlated with contemporaneous APACHE II scores (R(2) = 0.273; Spearman rho = 0.581; P < 0.001) and CRP (R(2) = 0.132; Spearman rho = 0.455, P < 0.001). Temporal profiling showed early tryptophan depletion and contemporaneous 3-hydroxykynurenine elevation. Furthermore, plasma concentrations of 3-hydroxykynurenine paralleled systemic inflammation and AP severity. These findings support the rationale for investigating early intervention with a KMO inhibitor, with the aim of reducing the incidence and severity of AP-associated organ dysfunction

Genetic polymorphisms associated with the inflammatory response in bacterial meningitis

BACKGROUND Bacterial meningitis (BM) is an infectious disease that results in high mortality and morbidity. Despite efficacious antibiotic therapy, neurological sequelae are often observed in patients after disease. Currently, the main challenge in BM treatment is to develop adjuvant therapies that reduce the occurrence of sequelae. In recent papers published by our group, we described the associations between the single nucleotide polymorphisms (SNPs) AADAT +401C > T, APEX1 Asn148Glu, OGG1 Ser326Cys and PARP1 Val762Ala and BM. In this study, we analyzed the associations between the SNPs TNF -308G > A, TNF -857C > T, IL-8 -251A > T and BM and investigated gene-gene interactions, including the SNPs that we published previously. METHODS The study was conducted with 54 BM patients and 110 healthy volunteers (as the control group). The genotypes were investigated via primer-introduced restriction analysis-polymerase chain reaction (PIRA-PCR) or polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) analysis. Allelic and genotypic frequencies were also associated with cytokine and chemokine levels, as measured with the x-MAP method, and cell counts. We analyzed gene-gene interactions among SNPs using the generalized multifactor dimensionality reduction (GMDR) method. RESULTS We did not find significant association between the SNPs TNF -857C > T and IL-8 -251A > T and the disease. However, a higher frequency of the variant allele TNF -308A was observed in the control group, associated with changes in cytokine levels compared to individuals with wild type genotypes, suggesting a possible protective role. In addition, combined inter-gene interaction analysis indicated a significant association between certain genotypes and BM, mainly involving the alleles APEX1 148Glu, IL8 -251 T and AADAT +401 T. These genotypic combinations were shown to affect cyto/chemokine levels and cell counts in CSF samples from BM patients. CONCLUSIONS In conclusion, this study revealed a significant association between genetic variability and altered inflammatory responses, involving important pathways that are activated during BM. This knowledge may be useful for a better understanding of BM pathogenesis and the development of new therapeutic approaches

5-Hydroxyanthranilic acid, a tryptophan metabolite, generates oxidative stress and neuronal death via p38 activation in cultured cerebellar granule neurones

The essential amino acid tryptophan is primarily metabolised through the kynurenine pathway, some components of which may be neurotoxic. We have now examined the potential toxicity of several kynurenine metabolites in relation to the generation of oxidative stress and activation of cell death signalling pathways in cultured cerebellar granule neurons. 3-Hydroxykynurenine (3HK), 3-hydroxyanthranilic acid (3HAA) and 5-hydroxyanthranilic acid (5HAA) induced cell death which increased with exposure time and compound concentration. The neurotoxic effects of 3HK, 3HAA and 5HAA were prevented by catalase, but not by superoxide dismutase. In addition, Western blot analysis demonstrated p38 activation due to 3HK or 5HAA treatment, although caspase-3 activation was not evident in either case. The results indicate that kynurenine metabolites can be neurotoxic via a caspase-3 independent mechanism, and that the minor metabolite 5HAA is as potent a toxin as the better documented compounds 3HK and 3HA

Vitamin B6 reduces hippocampal apoptosis in experimental pneumococcal meningitis

BACKGROUND Bacterial meningitis caused by Streptococcus pneumoniae leads to death in up to 30% of patients and leaves up to half of the survivors with neurological sequelae. The inflammatory host reaction initiates the induction of the kynurenine pathway and contributes to hippocampal apoptosis, a form of brain damage that is associated with learning and memory deficits in experimental paradigms. Vitamin B6 is an enzymatic cofactor in the kynurenine pathway and may thus limit the accumulation of neurotoxic metabolites and preserve the cellular energy status. The aim of this study in a pneumococcal meningitis model was to investigate the effect of vitamin B6 on hippocampal apoptosis by histomorphology, by transcriptomics and by measurement of cellular nicotine amide adenine dinucleotide content. METHODS AND RESULTS Eleven day old Wistar rats were infected with 1x10(6) cfu/ml of S. pneumoniae and randomized for treatment with vitamin B6 or saline as controls. Vitamin B6 led to a significant (p > 0.02) reduction of hippocampal apoptosis. According to functional annotation based clustering, vitamin B6 led to down-regulation of genes involved in processes of inflammatory response, while genes encoding for processes related to circadian rhythm, neuronal signaling and apoptotic cell death were mostly up-regulated. CONCLUSIONS Our results provide evidence that attenuation of apoptosis by vitamin B6 is multi-factorial including down-modulation of inflammation, up-regulation of the neuroprotective brain-derived neurotrophic factor and prevention of the exhaustion of cellular energy stores. The neuroprotective effect identifies vitamin B6 as a potential target for the development of strategies to attenuate brain injury in bacterial meningitis

Association of kynurenine aminotransferase II gene C401T polymorphism with immune response in patients with meningitis

<p>Abstract</p> <p><b>Background</b></p> <p>The kynurenine (KYN) pathway has been shown to be altered in several diseases which compromise the central nervous system (CNS) including infectious diseases such as bacterial meningitis (BM). The aim of this study was to assess single nucleotide polymorphisms (SNPs) in four genes of KYN pathway in patients with meningitis and their correlation with markers of immune response in BM.</p> <p>Methods</p> <p>One hundred and one individuals were enrolled in this study to investigate SNPs in the following genes: indoleamine-2,3-dioxygenase (<it>IDO1 </it>gene), kynureninase (<it>KYNU </it>gene), kynurenine aminotransferase I (<it>CCBL1 </it>gene), and kynurenine aminotransferase II (<it>AADAT </it>gene). SNP analyses were performed by primer-introduced restriction analysis-PCR (PIRA-PCR) followed by RFLP. Cytokines were measured using multiplex bead assay while immunoglobulins (IG) by immunodiffusion plates and NF-kappaB and c-Jun by dot blot assay.</p> <p>Results</p> <p>The variant allele of SNP <it>AADAT</it>+401C/T showed prevalent frequency in patients with BM. A significant decrease (<it>p </it>< 0.05) in TNF-α, IL-1β, IL-6, MIP-1αCCL3 and MIP-1β/CCL4 levels was observed in BM patients homozygous (TT) to the SNP <it>AADAT</it>+401C/T. Furthermore, a significant (<it>p </it>< 0.05) decrease in cell count was observed in cerebrospinal fluid (CSF) from patients with TT genotype. In addition, an increase in the IgG level in adults (<it>p </it>< 0.05) was observed. The variant allele for <it>KYNU</it>+715G/A was found with low frequency in the groups, and the SNPs in <it>IDO1</it>+434T/G, <it>KYNU</it>+693G/A, <it>CCBL1</it>+164T/C, and <it>AADAT</it>+650C/T had no frequency in this population.</p> <p><b>Conclusions</b></p> <p>This study is the first report of an association of SNP <it>AADAT</it>+401C/T with the host immune response to BM, suggesting that this SNP may affect the host ability in recruitment of leukocytes to the infection site. This finding may contribute to identifying potential targets for pharmacological intervention as adjuvant therapy for BM.</p

Alterations on cellular redox states upon infection and implications for host cell homeostasis

The cofactors nicotinamide adenine dinucleotide (NAD+) and its phosphate form, NADP+, are crucial molecules present in all living cells. The delicate balance between the oxidized and reduced forms of these molecules is tightly regulated by intracellular metabolism assuring the maintenance of homeostatic conditions, which are essential for cell survival and proliferation. A recent cluster of data has highlighted the importance of the intracellular NAD+/NADH and NADP+/NADPH ratios during host-pathogen interactions, as fluctuations in the levels of these cofactors and in precursors' bioavailability may condition host response and, therefore, pathogen persistence or elimination. Furthermore, an increasing interest has been given towards how pathogens are capable of hijacking host cell proteins in their own advantage and, consequently, alter cellular redox states and immune function. Here, we review the basic principles behind biosynthesis and subcellular compartmentalization of NAD+ and NADP+, as well as the importance of these cofactors during infection, with a special emphasis on pathogen-driven modulation of host NAD+/NADP+ levels and contribution to the associated immune response.(undefined)info:eu-repo/semantics/publishedVersio

C-terminal truncation of IFN-γ\gamma inhibits proinflammatory macrophage responses and is deficient in autoimmune disease

International audienceControlled macrophage differentiation and activation in the initiation and resolution of inflammation is crucial for averting progression to chronic inflammatory and autoimmune diseases. Here we show a negative feedback mechanism for proinflammatory IFN-$\gamma$ activation of macrophages driven by macrophage-associated matrix metalloproteinase 12 (MMP12). Through C-terminal truncation of IFN-$\gamma$ at 135Glu↓Leu136 the IFN-$\gamma$ receptor-binding site was efficiently removed thereby reducing JAK-STAT1 signaling and IFN-$\gamma$ activation of proinflammatory macrophages. In acute peritonitis this signature was absent in Mmp12$^{–/–}$ mice and recapitulated in Mmp12$^{+/+}$ mice treated with a MMP12-specific inhibitor. Similarly, loss-of-MMP12 increases IFN-$\gamma$–dependent proinflammatory markers and iNOS$^+$/MHC class II$^+$ macrophage accumulation with worse lymphadenopathy, arthritic synovitis and lupus glomerulonephritis. In active human systemic lupus erythematosus, MMP12 levels were lower and IFN-$\gamma$ higher compared to treated patients or healthy individuals. Hence, macrophage proteolytic truncation of IFN-$\gamma$ attenuates classical activation of macrophages as a prelude for resolving inflammation