Tryptophan metabolism and indoleamine 2,3-dioxygenase expression in coeliac disease

We have investigated the possible role of the metabolism of tryptophan and activity of the enzyme indoleamine 2,3-dioxygenase (IDO) in the immune regulation of coeliac disease (CD). Serum concentrations of tryptophan and its metabolites kinurenines were determined by high performance liquid chromatography in 24 patients with CD, seven patients with Crohn's disease and five healthy patients. We detected an increase of kynurenine (4.2 micromol/l +/- 0.27 versus 2.6 micromol/l +/- 0.54, P < 0002) and of the kynurenine/tryptophan ratio in supernatants of coeliac patients (11.5 micromol/l +/- 1.01 versus 6.5 micromol/l +/- 1.57, P < 0005) in comparison with healthy patients, respectively, and we found no differences with Crohn's disease patients. Immunohistochemistry analysis of intestinal biopsies from CD patients showed an increased expression of IDO, interferon-gamma, interleukin-10 and transforming growth factor-beta. Our data suggest that a mechanism(s) dependent on tryptophan catabolism might regulate the immune responses in CD.     

Correlation between tryptophan metabolism and the state of melaninogenesis

A study of the excretion of tryptophan metabolites and activity of liver tryptophan pyrrolase in black and white rabbits showed that the levels of kynurenin, kynurenic and xanthurenic acids, 3-hydroxykynurenin, anthranilic acid, and 5-hydroxyindoleacetic acid determined in the original urine before L-tryptophan loading differed in the two groups. No 3-hydroxyanthranilic acid was found in the original urine of the rabbits. After administration of L-tryptophan to albino rabbits, a sharp increase was observed in the excretion of all tryptophan metabolites investigated, but in black rabbits there was a sharper increase in the excretion of kynurenic and xanthurenic acids. The liver tryptophan pyrrolase reacts more intensively in white than in black rabbits to administration of L-tryptophan.Department of Biochemistry, Turkmenian Medical Institute, Ashkhabad. (Presented by Academician of the Academy of Medical Sciences of the USSR S. S. Debov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 12, pp. 1441–1444, December, 1976.     

Effective antiretroviral therapy reduces degradation of tryptophan in patients with HIV-1 infection

Antiretroviral therapy (ART) has a significant impact on HIV-1 RNA levels, the CD4 cell count, and immune activation. We examined whether these changes are associated with a change in the rate of tryptophan degradation (expressed as the kynurenine to tryptophan ratio, kyn/trp) as an estimate for the activity of interferon-gamma inducible enzyme indoleamine (, )-dioxygenase (IDO). Plasma levels of tryptophan, kynurenine, and neopterin were measured pretherapy and 6 months postinitiation of therapy in 45 patients with HIV-1 RNA levels of less than 1000 copies/ml 6 months after initiation of ART. Before ART, the patients had decreased tryptophan and increased kynurenine concentrations compared to healthy controls. During ART, average tryptophan levels increased; in the same time kynurenine and kyn/trp decreased (P < 0.001), although not to normal levels. Since pretherapy tryptophan concentrations correlated inversely with neopterin, and kynurenine correlated with viral load and neopterin but not with CD4 cell count, the data support the view that HIV production may induce immune activation and consequently tryptophan is degraded at a higher rate. In agreement, kyn/trp positively correlated with neopterin (r(s) = 0.60, P < 0.001), with virus load (r(s) = 0.37, P = 0.013), and very weakly with CD4(+) cells counts (r(s) = 0.30, P = 0.049). The change in the kyn/trp ratio during ART correlated more strongly with the change in neopterin levels (r(s) = 0.49, P = 0.001) than with the change in HIV RNA levels and weakly with the CD4 cell count. The data underscore the fact that both neopterin production and tryptophan degradation are triggered by immune activation. Tryptophan degradation is increased in HIV infection and partially reversed under ART. The data agree with the concept that immune activation is the common background of IDO activation which may be an important factor underlying T-cell hyporesponsiveness.     

The Angiotensin-Converting Enzyme Inhibitor Lisinopril Mitigates Memory and Motor Deficits in a Drosophila Model of Alzheimer’s Disease

The use of angiotensin-converting enzyme inhibitors (ACEis) has been reported to reduce symptoms of cognitive decline in patients with Alzheimer’s disease (AD). Yet, the protective role of ACEis against AD symptoms is still controversial. Here, we aimed at determining whether oral treatment with the ACEi lisinopril has beneficial effects on cognitive and physical functions in a Drosophila melanogaster model of AD that overexpresses the human amyloid precursor protein and the human β-site APP-cleaving enzyme in neurons. We found a significant impairment in learning and memory as well as in climbing ability in young AD flies compared to control flies. After evaluation of the kynurenine pathway of tryptophan metabolism, we also found that AD flies displayed a >30-fold increase in the levels of the neurotoxic 3-hydroxykynurenine (3-HK) in their heads. Furthermore, compared to control flies, AD flies had significantly higher levels of the reactive oxygen species (ROS) hydrogen peroxide in their muscle-enriched thoraces. Lisinopril significantly improved deficits in learning and memory and climbing ability in AD flies. The positive impact of lisinopril on physical function might be, in part, explained by a significant reduction in ROS levels in the thoraces of the lisinopril-fed AD flies. However, lisinopril did not affect the levels of 3-HK. In conclusion, our findings provide novel and relevant insights into the therapeutic potential of ACEis in a preclinical AD model.     

Maternal oral contraceptive use and atopic diseases in the offspring

BACKGROUND: This study examined the association of maternal oral contraceptive (OC) use - before and after birth - and atopic manifestations in the offspring. METHODS: A total of 2754 East German children aged 5-14 years participated in a cross-sectional survey in 1998-99. The standardized parental questionnaire in 1998-99 included data on atopic diseases, socio-economic factors, parental atopy and maternal OC use. Specific immunoglobulin E against common inhalant allergens was measured by radioallergosorbent test (RAST). RESULTS: Maternal OC use before birth was associated with a higher risk of atopic diseases in the offspring compared with children of mothers who had never taken OC [asthma: odds ratio (OR) 1.6; 95% confidence interval (CI): 0.9-3.0; allergic rhinitis: OR 1.5; CI: 0.96-2.2; atopic eczema: OR 2.6; CI: 1.6-4.3; atopic sensitization: OR 1.5; CI: 0.97-2.2]. However, the effect estimates for maternal OC use after birth compared with the never users showed quite similar effects for these atopic conditions. No relations were observed between the prevalences of atopic diseases and maternal age at beginning of OC use, the duration of OC use, the type of contraceptive or maternal age at birth. CONCLUSION: This study raises doubts in a true biological association between OC use and atopic diseases.     

大肠杆菌生物合成中心代谢途径的改造及其对工程菌色氨酸产量的影响

目的改造大肠杆菌色氨酸生物合成的中心代谢途径，以进一步提高色氨酸产量。 方法根据ppsA和tktA基因序列分别合成引物行PCR扩增，将PCR扩增所得PLacO1-tktA-T1片段和pZA31质粒连接，经筛选鉴定正确的pZA31-tktA重组质粒和PCR扩增所得PLacO1-ppsA-T1片段连接，构建pZA31-ppsA-tktA重组质粒，并进行测序鉴定。将鉴定正确的pZA31-ppsA-tktA和pZE12-aroG^fbr-trpED^fbr重组质粒共转化至E.coli MG1655ΔRT-R，获得的重组菌株命名为E.coli MG1655ΔRT-R[pZA31-ppsA-tktA/pZE12-aroG^fbr-trpED^fbr]（工程菌）；以pZE12-aroG^fbr-trpED^fbr重组质粒转化至E.coli MG1655ΔRT-R得到的重组菌株E.coli MG1655ΔRT-R[pZE12-aroG^fbr-trpED^fbr]作为对照菌株，加入异丙基-β-D-硫代半乳糖苷（IPTG）诱导表达，3h后收集部分菌体行ppsA、tktA酶活性测定，其余发酵液继续培养4～5h后，监测调整培养基中葡萄糖浓度和pH值保持不变，48h后检测色氨酸产量。 结果PCR扩增所得片段均与预期DNA表达片段大小一致；pZA31-ppsA-tktA重组质粒测序显示，克隆的tktA和ppsA基因序列与报告序列完全相同。工程菌ppsA和tktA酶活性（U）与对照菌株比较，分别提高了3和3.5倍（分别为0.25±0.04vs.0.08±0.02，P〈0.05；0.21±0.03vs.0.06±0.02，P〈0.05）；色氨酸产量（g/L）与对照菌株比较，提高了1.3倍（1.10±0.05vs.0.80±0.05，P〈0.05）。 结论成功改造了大肠杆菌色氨酸生物合成的中心代谢途径，进一步提高了色氨酸产量，为构建高产色氨酸基因工程菌打下了基础。     

The role of vitamin D in the immunopathogenesis of allergic skin diseases

Vitamin D plays key roles in innate and adaptive immunity through the stimulation of Toll-like receptors, increasing pro-inflammatory cytokine production, and possibly enhancing T helper type 2 responses. These mechanisms may explain the growing body of evidence connecting vitamin D to allergic diseases, including asthma, food allergies, and allergic rhinitis. The data relating vitamin D to allergic skin diseases are equivocal with studies linking both high and low vitamin D levels to an increased risk of developing atopic dermatitis. In this paper, we describe the role of vitamin D in the immunopathogenesis of atopic dermatitis and other allergic skin diseases.     

Regulatory functions of B cells in allergic diseases

B cells are essentially described for their capacity to produce antibodies ensuring anti‐infectious immunity or deleterious responses in the case of autoimmunity or allergy. However, abundant data described their ability to restrain inflammation by diverse mechanisms. In allergy, some regulatory B‐cell subsets producing IL‐10 have been recently described as potent suppressive cells able to restrain inflammatory responses both in vitro and in vivo by regulatory T‐cell differentiation or directly inhibiting T‐cell‐mediated inflammation. A specific deficit in regulatory B cells participates to more severe allergic inflammation. Induction of allergen tolerance through specific immunotherapy induces a specific expansion of these cells supporting their role in establishment of allergen tolerance. However, the regulatory functions carried out by B cells are not exclusively IL‐10 dependent. Indeed, other regulatory mechanisms mediated by B cells are (i) the production of TGF‐β, (ii) the promotion of T‐cell apoptosis by Fas–Fas ligand or granzyme‐B pathways, and (iii) their capacity to produce inhibitory IgG4 and sialylated IgG able to mediate anti‐inflammatory mechanisms. This points to Bregs as interesting targets for the development of new therapies to induce allergen tolerance. In this review, we highlight advances in the study of regulatory mechanisms mediated by B cells and outline what is known about their phenotype as well as their suppressive role in allergy from studies in both mice and humans.     

Role of IL-9 in the pathophysiology of allergic diseases

Considerable evidence from both human and animal studies indicates that CD4(+) cells are the predominant cell type involved in the regulation of airway inflammation through the expression of T(H)2-type cytokines. The effects of T(H)2-type cytokines, particularly IL-4 and IL-5, on inflammatory and structural cells in airways have been studied in great detail. They were shown to be important for inflammatory cell maturation, activation and proliferation, IgE production, chemokine expression, mucus secretion, and bronchial hyperresponsiveness. Recent work has shown the potential importance of another T(H)2-type cytokine, IL-9. The development of transgenic mice overexpressing IL-9 has suggested a key role for this cytokine in the development of the asthmatic phenotype, including eosinophilic inflammation, bronchial hyperresponsiveness, elevated IgE levels, and increased mucus secretion. IL-9 has been shown to act on many cell types involved in asthma, including T cells, B cells, mast cells, eosinophils, neutrophils, and epithelial cells, and thus might be important in the pathophysiology of allergic asthma.     

Perinatal maternal application of Lactobacillus rhamnosus GG suppresses allergic airway inflammation in mouse offspring

BACKGROUND: Clinical studies indicate that maternal exposure to probiotic bacteria may protect from the development of allergic disease later in life. OBJECTIVE: The purpose of this study was to analyse the effects of a perinatal Lactobacillus rhamnosus GG (LGG) supplementation on the development of allergic disorders in offspring. METHODS: Female BALB/c mice received intragastric LGG every other day before conception, during pregnancy and lactation (perinatal supplementation group) or before conception and during pregnancy only (prenatal supplementation group). Cytokine expression of placental tissues was examined. Offspring of LGG-supplemented and sham-exposed mothers were sensitized to Ovalbumin (OVA), followed by aerosol allergen challenges. Development of experimental asthma was assessed by bronchoalveolar lavage analysis, lung histology and lung function measurement. Cytokine production of splenic mononuclear cells was analysed following in vitro stimulation. RESULTS: Intestinal colonization with LGG was observed in mother mice only, but not in the offspring. However, a reduced expression of TNF-alpha, IFN-gamma, IL-5 as well as IL-10 was observed in mice derived from perinatally LGG-supplemented mothers, whereas IL-13 and IL-4 expression remained unchanged. Moreover, in offspring of prenatally or perinatally LGG-supplemented mothers allergic airway and peribronchial inflammation as well as goblet cell hyperplasia were significantly reduced as compared with mice derived from non-supplemented mothers. In contrast, airway hyperresponsiveness to methacholine was not affected. Exposure to LGG during pregnancy only shifted the placental cytokine expression pattern with a markedly increased TNF-alpha level. CONCLUSION: Our data suggest that LGG may exert beneficial effects on the development of experimental allergic asthma, when applied in a very early phase of life. Immunological effects are, at least in parts, mediated via the placenta, probably by induction of pro-inflammatory cell signals.     

Role of Treg in immune regulation of allergic diseases

Allergy is a Th2‐mediated disease that involves the formation of specific IgE antibodies against innocuous environmental substances. The prevalence of allergic diseases has dramatically increased over the past decades, affecting up to 30% of the population in industrialized countries. The understanding of mechanisms underlying allergic diseases as well as those operating in non‐allergic healthy responses and allergen‐specific immunotherapy has experienced exciting advances over the past 15 years. Studies in healthy non‐atopic individuals and several clinical trials of allergen‐specific immunotherapy have demonstrated that the induction of a tolerant state in peripheral T cells represent a key step in healthy immune responses to allergens. Both naturally occurring thymus‐derived CD4⁺CD25⁺FOXP3⁺ Treg and inducible type 1 Treg inhibit the development of allergy via several mechanisms, including suppression of other effector Th1, Th2, Th17 cells; suppression of eosinophils, mast cells and basophils; Ab isotype change from IgE to IgG4; suppression of inflammatory DC; and suppression of inflammatory cell migration to tissues. The identification of the molecules involved in these processes will contribute to the development of more efficient and safer treatment modalities.     

An NAD+ biosynthetic pathway enzyme functions cell non‐autonomously in C. elegans development

Background: Disruption of cellular metabolite levels can adversely impact development. Specifically, loss‐of‐function of the C. elegans NAD⁺ salvage biosynthesis gene PNC‐1 results in an array of developmental phenotypes. Intriguingly, PNC‐1 and its functional equivalent in vertebrates are secreted, but the contributions of the extracellular enzymes are poorly understood. We sought to study the tissue‐specific requirements for PNC‐1 expression and to examine the role of the secreted isoform. Results: A thorough analysis of PNC‐1 expression did not detect expression in tissues that require PNC‐1 function. Limited expression of both the secreted and intracellular PNC‐1 isoforms provided function at a distance from the tissues with phenotypes. We also find that the secreted isoform contributes to in vivo PNC‐1 activity. Furthermore, uv1 cell survival has the most stringent requirements in terms of PNC‐1 expression pattern or level. Conclusions: Using careful promoter analysis and a restricted expression approach, we have shown that both the secreted and the intracellular PNC‐1 isoforms function cell non‐autonomously, and that the PNC‐1a isoform is functionally relevant in vivo. Our work suggests a model where PNC‐1 function is provided cell non‐autonomously by a mix of intra and extracellular activity, most likely requiring NAD⁺ salvage metabolite transport between tissues. Developmental Dynamics 243:965–976, 2014. © 2014 Wiley Periodicals, Inc.     

Prevalence of allergic diseases in schoolchildren in relation to family history upper respiratory infections, and residential characteristics

The prevalences of asthma, allergic rhinitis (AR), and eczema were analyzed in relation to retrospective risk factors from birth in a questionnaire study of schoolchildren in two areas covering the whole climatic span of Sweden: the Göteborg area on the southwestern coast (7-year-olds, n = 1649) and Kiruna, a mining town in the northernmost inland mountains (7–9-year-olds, n = 832). The strongest background factor, a family history of the diseases, was more common in children with another strong risk factor, particularly for asthma: high frequency of upper respiratory tract infection (URTI). Other significant risk factors related to high indoor humidity caused an increased prevalence of both allergic diseases and URTI. Active mechanical ventilation of the homes caused a slight reduction of the prevalence of allergic diseases, and repainting or new wallpaper in the bedroom of the child after birth caused a moderately increased risk of allergic disease. This study illustrates the interaction between genetic and environmental risk factors with special emphasis on factors related to an unventilated indoor climate, which may have substantially contributed to the current increase of the diseases in the country.