犬尿氨酸氨基转移酶和犬尿喹啉酸在自发性高血压大鼠中的变化

目的 犬尿氨酸氨基转移酶(KAT)催化犬尿氨酸(KYN)生成犬尿喹啉酸(KYNA).研究表明中枢KAT及KYNA可能参与血压调节,但外周KAT变化及KYNA生成与血压的关系尚无报道.检测肾脏KATⅡ基因表达,KAT活性,及尿KYNA含量在自发性高血压大鼠(SHR)和WKY大鼠(正常对照组)的变化.方法 采用实时定量PCR技术检测KATⅡ基因表达,高效液相色谱(HPLC)检测尿KYNA及KAT活性(通过测定其酶促反应产物KYNA).结果 虽然肾皮质和肾髓质KATⅡ基因mRNA表达在SHR与WKY之间差异无统计学意义(P>0.05);但SHR肾皮质KAT的活性显著低于WKY[(0.563±0.037) vs (1.037±0.131)μmol/(g·min),P=0.017].同时发现SHR组尿KYNA含量在显著低于WKY组[(7.8±1.8) vs (19.9±3.5)μmol/24 h,P=0.013].相关分析显示,肾皮质KAT的活性(r=-0.418, P=0.023)和尿KYNA含量(r=-0.723,P=0.001)与血压都呈显著负相关.结论 SHR大鼠肾皮质KAT活性降低及尿KYNA含量减少,提示除中枢KAT及KYNA变化外,肾皮质KAT活性变化导致的KYNA改变亦可能影响血压.     

犬尿喹啉酸及3-羟基犬尿氨酸与阿尔茨海默病的相关性研究

目的探讨犬尿氨酸(KYN)通路主要代谢产物犬尿喹啉酸(KYNA)和3-羟基犬尿氨酸(3-HK)与AD的关系,以及KYN通路限速酶犬尿氨酸3-单加氧酶(KMO)基因多态性与AD的相关性。方法选取AD患者198例为AD组和健康体检者192例为对照组,采用简易智能状态检查量表(MMSE)、蒙特利尔认知评估量表(MoCA)、日常生活活动能力量表(ADL)、临床痴呆评定量表(CDR)评估,检测各组KMOrs2275163、rs1053230等位基因频率和基因型频率。结果 AD组MMSE和MoCA评分明显低于对照组,ADL和CDR评分明显高于对照组(P0.05,P0.01)。AD组血浆KYN水平明显低于对照组,KYNA、3-HK及3-HK/KYN明显高于对照组[(1.2±0.2)mmol/L vs(1.3±0.2)mmol/L,P=0.043;(40.0±8.8)nmol/L vs(28.4±9.2)nmol/L,P=0.036;(108.5±14.6)nmol/L vs(35.2±5.6)nmol/L,P=0.011;(94.3±11.9)vs(28.9±9.5),P=0.016]。对照组与AD组rs2275163、rs1053230等位基因频率及基因型频率比较,差异无统计学意义(P0.05)。结论 KYN通路代谢产物水平在AD患者中发生变化,在AD发病过程中可能发挥作用,可能成为AD诊断的血清学标志物。     

吲哚胺2,3-二加氧酶抑制剂对慢性脑低灌注大鼠认知功能损害的行为学改善

目的观察使用吲哚胺2,3-二加氧酶(IDO)抑制剂后慢性脑低灌注大鼠认知功能损害的行为学改善,及血犬尿氨酸(KYN)、犬尿喹啉酸(KYNA)水平的变化。方法雄性Wistar大鼠30只,随机分为假手术组,对照组和IDO抑制剂组,各10只,后2组采用改良的永久性双侧颈总动脉结扎术制作慢性脑低灌注大鼠模型。Morris水迷宫检测大鼠空间学习与记忆能力变化,高效液相色谱-荧光检测法检测血KYN、KYNA的水平,免疫组织化学检测大鼠海马CA1区IFN-γ、TNF-α表达。结果与假手术组比较,对照组IFN-γ、TNF-α表达明显升高(P<0.05);与对照组比较,IDO抑制剂组大鼠第4、5天逃避潜伏期缩短,平台象限游泳距离百分比增加,KYN[(15.33±0.90)μmol/L vs(1.69±0.94)μmol/L]及KYNA[(39.51±3.81)μmol/L vs(25.66±6.80)μmol/L]水平明显降低(P<0.05),但IFN-γ、TNF-α表达无显著差异(P>0.05)。结论 IDO抑制剂不影响炎性因子表达,但可减少血KYN及KYNA表达,可改善慢性脑低灌注所致的认知功能损害的空间学习及记忆能力。     

脑组织过表达犬尿氨酸酶的转基因小鼠对血压的影响

目的本研究旨在构建脑组织选择性过表达犬尿氨酸酶（Kynu）的转基因小鼠,在整体水平研究KYNU活性增强对血压的影响。方法构建在神经元特异性烯醇酶（NSE）启动子控制下的大鼠Kynu表达载体,采用受精卵原核注射的方法获得脑组织过表达Kynu的转基因小鼠。采用PCR鉴定转基因阳性小鼠;荧光实时定量逆转录PCR（Real Time RT-PCR）、蛋白免疫印迹技术（Western blot）免疫组织化学方法检测转基因的表达;高效液相色谱（HPLC）检测KYNU的活性;鼠尾法测量小鼠血压。结果转基因小鼠与同窝阴性对照小鼠相比,脑干组织中KYNU的表达有显著的差异（P〈0.01）,不同发育阶段转基因小鼠脑干组织Kynu活性与同窝阴性对照小鼠相比,存在显著差异（12周,0.1613±0.0153 vs.0.0019±0.0002 nmol/min/mg,P〈0.01;35周,0.5817±0.1476vs. 0.0038±0.0004 nmol/min/mg,P〈0.05;〉1年,0.1909±0.0115 vs.0.0036±0.0011 nmol/min/ mg,P〈0.01）。但两组小鼠的收缩压没有显著差异（12周,113.6±3.9 Vs.109.3±2.3 mmHg,P〉0.05;35周,114.6±2.5 vs.113.1±4.2 mmHg,P〉0.05;〉1年,121.3±2.6 vs.123.9±3.5 mmH8,P〉0.05）。给予游泳应激刺激后,两组小鼠间的血压也无显著差别。结论脑干组织Kynu的过表达并没有引起日间的和应激的血压值改变,KYNU在血压调节中的作用有待于进一步的研究。     

依那普利和氯沙坦对自发性高血压大鼠肾皮质环核苷酸水平的影响

目的　观察肾脏环磷酸腺苷 (cAMP)、环磷酸鸟苷 (cGMP)和一氧化氮 (NO)水平与高血压的关系 ,以及依那普利和氯沙坦降压治疗对自发性高血压大鼠 (SHR)肾皮质cAMP、cGMP和NO水平的影响。方法　 14周龄雄性SHR分三组 (n=6) :依那普利组 15mg·kg- 1·d- 1灌胃 ;氯沙坦组 3 7 5mg·kg- 1·d- 1灌胃 ;SHR对照组以等量蒸馏水灌胃。Wistar kyoto(WKY)对照组亦以等量蒸馏水灌胃。采用放射免疫法及Griess法检测肾皮质cAMP、cGMP、血管紧张素Ⅱ (AngⅡ )和NO代谢产物亚硝酸盐 (NO3 - )水平。结果　SHR对照组肾皮质AngⅡ含量较WKY组显著升高 (P <0 0 1) ;与SHR对照组相比 ,依那普利组AngⅡ含量显著降低 (P <0 0 1) ,氯沙坦组AngⅡ含量增加 (P <0 0 5)。与WKY相比 ,SHR对照组cAMP水平低于WKY组 (P <0 0 1) ,依那普利组cAMP水平明显高于SHR对照组 (P <0 0 5) ,氯沙坦组cAMP较SHR对照组有升高趋势 ,但无显著性差异 (P >0 0 5) ;SHR对照组肾皮质NO3 - 、cGMP含量较WKY组显著减少 (P <0 0 1) ;依那普利治疗组NO3- 、cGMP含量较SHR对照组显著增加 (P <0 0 1) ,氯沙坦组与SHR对照组相比 ,NO3 - 、cGMP含量增加(分别为P <0 0 1,P <0 0 5) ,各组NO3- 水平与cGMP水平呈正相关 (r =0 8689,P <0 0 1)。结论　SHR肾     

依那普利和氯沙坦对自发性高血压大鼠同型半胱氨酸、环磷酸腺苷水平的影响

目的观察依那普利和氯沙坦降压治疗对自发性高血压大鼠(SHR)血浆同型半胱氨酸(Hcy)、叶酸、维生素B12(VB12)和肾脏血管紧张素Ⅱ(AngⅡ)、环磷酸腺苷(cAMP)水平的影响。方法14w龄雄性SHR分三组。依那普利组15mg/(kg·d)灌胃;氯沙坦组37.5mg/(kg·d)灌胃;SHR对照组及WistarKyoto大鼠(WKY)对照组均以等量蒸馏水灌胃。2w后测定血浆Hcy、叶酸、VB12水平及肾皮质cAMP、AngⅡ含量。结果SHR对照组与WKY对照组相比血浆Hcy、叶酸水平无显著性差异(P>0.05);VB12升高(P<0.05);WKY组及SHR对照组的血压水平与Hcy、VB12水平无显著相关(r=-0.11,P=0.718),血浆Hcy与VB12水平负相关(r=-0.8131,P<0.05);依那普利、氯沙坦对Hcy、叶酸及VB12水平无影响;与SHR对照组相比,依那普利组AngⅡ含量减少(P<0.01);氯沙坦组AngⅡ含量增加(P<0.05);SHR对照组肾皮质cAMP水平低于WKY对照组(P<0.01);依那普利组cAMP显著高于SHR对照组(P<0.01)。结论在满足适量摄入叶酸并且无过量蛋氨酸负荷条件下,Hcy可能没有参与对SHR基础血压的影响;依那普利和氯沙坦对SHR血浆Hcy、叶酸、VB12水平无影响;SHR肾皮质cAMP水平的下降可能并非继发于高血压;依那普利可通过增加SHR肾皮质cAMP水平发挥有益作用。     

奥美沙坦通过延髓腹外侧区AT1受体减弱自发高血压大鼠血管紧张素Ⅱ引发的中枢性升压反应

目的 探讨奥美沙坦对自发性高血压大鼠(SHR)外源性血管紧张素Ⅱ(AngⅡ)引发的中枢性升压反应的影响以及与延髓腹外侧头端区(RVLM)血管紧张素Ⅱ1型受体(AT1)的关系.方法 实验大鼠分为SHR对照组(n=20,正常饮水)、奥美沙坦组(n=20,给予奥美沙坦30 mg·kg-1·d-1)和WKY组(n=20,WKY大鼠,正常饮水).4 w后,三组大鼠腹腔麻醉,开颅定位RVLM后,股动静脉插管,观察注射AngⅡ前后血压和心率.采用逆转录-聚合酶链反应(RT-PCR)和免疫印迹方法检测各组RVLM内AT1受体mRNA和蛋白的水平,并进行光密度测定.结果 饲养中奥美沙坦组鼠尾血压能够达标.RVLM微量注射AngⅡ后三组大鼠的平均动脉压(MAP)不同程度升高,奥美沙坦组MAP升高幅度明显低于SHR组[(26.3±0.75)vs(47.2±1.41)mmHg,P＜0.01],但仍高于WKY组[(21.5±0.72)mmHg,P＜0.05].三组大鼠心率(HR)均有所升高,但差异无统计学意义.奥美沙坦组RVLM内AT1受体mRNA平均光密度明显低于SHR组[(0.94±0.41) vs (2.41±0.37),P＜0.01],但高于WKY组(0.81±0.22,P＜0.05).奥美沙坦组RVLM内AT1受体蛋白平均光密度明显低于SHR组[(0.51±0.09) vs (0.93±0.07),P＜0.01)],但高于WKY组(0.43±0.03,P＜0.05).结论 长期口服奥美沙坦能够通过降低RVLM组织中AT1受体水平,显著减弱SHR RVLM区微量注射AngⅡ引起的升压反应.     

自发性高血压大鼠肾上腺髓质素2水平的变化

背景 肾上腺髓质素2(ADM2)是2004年2月由日本学者所报道的,被认为是降钙素/降钙素基因相关肽超家族的一个新肽.这与2003年11月美国斯坦福大学Dr.Roh等人发现的垂体中叶素在核苷酸和氨基酸序列上完全一致,二者被认为是同物异名.该家族的已有成员包括肾上腺髓质素、降钙素基因相关肽、降钙素和胰岛淀粉样多肽.目前研究结果表明,肾上腺髓质素2参与了心血管的调节.目的 研究自发性高血压大鼠(SHR)血浆ADM2[即:垂体中叶素(IMD)]的含量和在组织中水平的升降、基因表达的变化、血浆ADM2含量与血压和心质量/体质量(HM/BM)的相互关系.方法 11周龄的雄性SHR 8只为实验组,同龄的雄性Wistar Kyoto(WKY)大鼠8只为对照组.放射免疫分析方法测定血浆和组织中ADM2的含量;RT-PCR方法测定组织中ADM2的mRNA表达;心室导管方法测定血压和心功能的变化.结果 1)与WKY大鼠相比,SHR的血浆、心肌和主动脉中ADM2的含量显著增高,分别为50.0%[(317.2±25.2)vs(211.4±15.0)ng/L,P＜0.01]、46.5%[(293.6±34.7)vs(200.4±21.6)ng/g,P＜0.05]和32.1%[(1009.0±50.1) vs(763.8±35.0)ng/g,P＜0.01];2)SHR心肌和主动脉中ADM2的mRNA水平高于WKY大鼠,分别升高76.11%[(0.75±0.33)vs(0.46±0.26)%,P＜0.05]和171.1%[(1.43±0.36)%vs(0.66±0.35)%,P＜0.01];3)实验组的ADM2血浆含量和收缩压呈显著负相关(r=-0.822,P＜0.05).结论 ADM2作为一种心血管的活性肽,在血压调节和心肌保护过程中具有重要的意义.     

犬尿氨酸代谢与血压调节

色氨酸犬尿氨酸代谢通路涉及一系列酶促反应，生成多种具有生物活性的化合物，参与许多病理生理过程。近年来发现其代谢途径中犬尿氨酸酶、犬尿氨酸氨基转移酶的催化反应产物可能与血压的调节有关。本文就目前色氨酸犬尿氨酸代谢通路与血压调节关系的相关研究进行论述。     

依那普利和氯沙坦对自发性高血压大鼠肾皮质环核苷酸水平的影响

目的观察肾脏环磷酸腺苷(cAMP)、环磷酸鸟苷(cGMP)和一氧化氮(NO)水平与高血压的关系,以及依那普利和氯沙坦降压治疗对自发性高血压大鼠(SHR)肾皮质cAMP、cGMP和NO水平的影响.方法 14周龄雄性SHR分三组(n=6)依那普利组15 mg*kg-1*d-1灌胃;氯沙坦组37.5 mg*kg-1*d-1灌胃;SHR对照组以等量蒸馏水灌胃.Wistar-kyoto(WKY)对照组亦以等量蒸馏水灌胃.采用放射免疫法及Griess法检测肾皮质cAMP、cGMP、血管紧张素Ⅱ(AngⅡ)和NO代谢产物亚硝酸盐(NO3-)水平.结果 SHR对照组肾皮质Ang Ⅱ含量较WKY组显著升高(P<0.01);与SHR对照组相比,依那普利组Ang Ⅱ含量显著降低(P<0.01),氯沙坦组Ang Ⅱ含量增加(P<0.05).与WKY相比,SHR对照组cAMP水平低于WKY组(P<0.01),依那普利组cAMP水平明显高于SHR对照组(P<0.05),氯沙坦组cAMP较SHR对照组有升高趋势,但无显著性差异(P>0.05);SHR对照组肾皮质NO3-、cGMP含量较WKY组显著减少(P<0.01);依那普利治疗组NO3-、cGMP含量较SHR对照组显著增加(P<0.01),氯沙坦组与SHR对照组相比,NO3-、cGMP含量增加(分别为P<0.01,P<0.05),各组NO3-水平与cGMP水平呈正相关(r=0.8689,P<0.01).结论 SHR肾皮质cAMP、cGMP 显著低于WKY,依那普利和氯沙坦均可升高SHR的cGMP水平,依那普利还可改善SHR肾cAMP代谢.     

Kynurenine plays an immunosuppressive role in 2,4,6-trinitrobenzene sulfate-induced colitis in mice

BACKGROUND Inflammatory bowel disease,such as Crohn’s disease and ulcerative colitis,is characterized by chronic intestinal inflammation leading to intestinal mucosal damage.Inflammatory bowel disease causes dysregulation of mucosal T cell responses,especially the responses of CD4+T cells.Previously,we demonstrated that indoleamine-2,3-dioxygenase plays an immunosuppressive role in 2,4,6-trinitrobenzene sulfate(TNBS)-induced colitis.Although indoleamine-2,3-dioxygenase exerts immunosuppressive effects by altering the local concentration of tryptophan(Trp)and immunomodulatory Trp metabolites,the specific changes in immune regulation during colitis caused by Trp metabolites and its related enzymes remain unclear.AIM To investigate role of kynurenine 3-monooxygenase(KMO)in TNBS-induced colitis and involvement of Trp metabolites in maintenance of intestinal homeostasis.METHODS Colitis was induced in eight-week-old male KMO+/+or KMO−/−mice of C57BL/6N background using TNBS.Three days later,the colon was used for hematoxylin-eosin staining for histological grading,immunohistochemical or immunofluorescence staining for KMO,cytokines,and immune cells.Inflammatory and anti-inflammatory cytokines were measured using quantitative RT-PCR,and kynurenine(Kyn)pathway metabolites were measured by high-performance liquid chromatography.The cell proportions of colonic lamina propria and mesenteric lymph nodes were analyzed by flow cytometry.RESULTS KMO expression levels in the colonic mononuclear phagocytes,including dendritic cells and macrophages increased upon TNBS induction.Notably,KMO deficiency reduced TNBS-induced colitis,resulting in an increased frequency of Foxp3+regulatory T cells and increased mRNA and protein levels of antiinflammatory cytokines,including transforming growth factor-βand interleukin-10.CONCLUSION Absence of KMO reduced TNBS-induced colitis via generation of Foxp3+regulatory T cells by producing Kyn.Thus,Kyn may play a therapeutic role in colon protection during colitis.     

Upregulated Kynurenine Pathway Enzymes in Aortic Atherosclerotic Aneurysm: Macrophage Kynureninase Downregulates Inflammation

Aims: Inflammation and hypertension contribute to the progression of atherosclerotic aneurysm in the aorta. Vascular cell metabolism is regarded to modulate atherogenesis, but the metabolic alterations that occur in atherosclerotic aneurysm remain unknown. The present study aimed to identify metabolic pathways and metabolites in aneurysmal walls and examine their roles in atherogenesis. Methods: Gene expression using microarray and metabolite levels in the early atherosclerotic lesions and aneurysmal walls obtained from 42 patients undergoing aortic surgery were investigated (early lesion n =11, aneurysm n =35) and capillary electrophoresis–time-of-flight mass spectrometry (early lesion n =14, aneurysm n =38). Using immunohistochemistry, the protein expression and localization of the identified factors were examined (early lesion n =11, non-aneurysmal advanced lesion n =8, aneurysm n =11). The roles of the factors in atherogenesis were analyzed in macrophages derived from human peripheral blood mononuclear cells. Results: Enrichment analysis using 35 significantly upregulated genes (log2 ratio, ＞3) revealed the alteration of the kynurenine pathway. Metabolite levels of tryptophan, kynurenine, and quinolinic acid and the kynurenine-to-tryptophan ratio were increased in the aneurysmal walls. Gene and protein expression of kynureninase and kynurenine 3-monooxygenase were upregulated and localized in macrophages in the aneurysmal walls. The silencing of kynureninase in the cultured macrophages enhanced the expression of interleukin-6 and indoleamine 2,3-dioxygenase 1. Conclusion: Our study suggests the upregulation of the kynurenine pathway in macrophages in aortic atherosclerotic aneurysm. Kynureninase may negatively regulate inflammation via the kynurenine pathway itself in macrophages.     

Alteration of fecal tryptophan metabolism correlates with shifted microbiota and may be involved in pathogenesis of colorectal cancer

BACKGROUNDGut tryptophan (Trp) metabolites are produced by microbiota and/or host metabolism. Some of them have been proven to promote or inhibit colorectal cancer (CRC) in vitro and animal models. We hypothesized that there is an alteration of gut Trp metabolism mediated by microbiota and that it might be involved in the pathogenesis of cancer in patients with CRC.AIMTo investigate the features of Trp metabolism in CRC and the correlation between fecal Trp metabolites and gut microbiota.METHODSSeventy-nine patients with colorectal neoplastic lesions (33 with colon adenoma and 46 with sporadic CRC) and 38 healthy controls (HCs) meeting the inclusion and exclusion criteria were included in the study. Their demographic and clinical features were collected. Fecal Trp, kynurenine (KYN), and indoles (metabolites of Trp metabolized by gut microbiota) were examined by ultraperformance liquid chromatography coupled to tandem mass spectrometry. Gut barrier marker and indoleamine 2,3-dioxygenase 1 (IDO1) mRNA were analyzed by quantitative real-time polymerase chain reaction. Zonula occludens-1 (ZO-1) protein expression was analyzed by immunohistochemistry. The gut microbiota was detected by 16S ribosomal RNA gene sequencing. Correlations between fecal metabolites and other parameters were examined in all patients.RESULTSThe absolute concentration of KYN [1.51 (0.70, 3.46) nmol/g vs 0.81 (0.64, 1.57) nmol/g, P = 0.036] and the ratio of KYN to Trp [7.39 (4.12, 11.72) × 10^-3 vs 5.23 (1.86, 7.99) × 10^-3, P = 0.032] were increased in the feces of patients with CRC compared to HCs, while the indoles to Trp ratio was decreased [1.34 (0.70, 2.63) vs 2.46 (1.25, 4.10), P = 0.029]. The relative ZO-1 mRNA levels in patients with CRC (0.27 ± 0.24) were significantly lower than those in HCs (1.00 ± 0.31) (P < 0.001), and the relative IDO1 mRNA levels in patients with CRC [1.65 (0.47-2.46)] were increased (P = 0.035). IDO1 mRNA levels were positively associated with the KYN/Trp ratio (r = 0.327, P = 0.003). ZO-1 mRNA and protein levels were positively correlated with the indoles/Trp ratio (P = 0.035 and P = 0.009, respectively). In addition, the genera Asaccharobacter (Actinobacteria) and Parabacteroides (Bacteroidetes), and members of the phylum Firmicutes (Clostridium XlVb, Fusicatenibacter, Anaerofilum, and Anaerostipes) decreased in CRC and exhibited a positive correlation with indoles in all subjects.CONCLUSIONAlteration of fecal Trp metabolism mediated by microbiota is associated with intestinal barrier function and tissue Trp metabolism, and may be involved in the pathogenesis of CRC.     

Inhibition by kynurenine metabolites of proinsulin synthesis in isolated pancreatic islets

Summary The effect of kynurenine metabolites on insulin biosynthesis was investigated in isolated pancreatic islets of the rat. Both quinaldic acid and 8-hydroxyquinaldic acid were found to produce significant inhibition of the proinsulin synthesis. However, the conversion process of proinsulin to insulin in the islet was not affected by these kynurenine metabolites. Furthermore, the inhibitory effect of these end-metabolites of kynurenine was characterized by preferential inhibition of proinsulin synthesis as distinct from non-insulin protein synthesis in the islet. In contrast to the significant inhibitory effect of quinaldic acid and 8-hydroxyquinaldic acid on proinsulin synthesis, xanthurenic acid and kynurenic acid were far less effective, and L-tryptophan, L-kynurenine, 3-hydroxyanthranilic acid and quinolinic acid showed little ability to inhibit proinsulin synthesis in islets. Preliminary data from this work were presented at the 9th Congress of the IDF, New Delhi, India (Excerpta Medica Foundation Congress Series no. 400; p. 8) and at the 2nd International Meeting on Tryptophan Metabolism, Madison/Wisc., U.S.A., August 10–12, 1977. On leave from the Department of Internal Medicine, Kanazawa University School of Medicine, Kanazawa, Japan.     

Kynurenine pathway alteration in acute pancreatitis and its role as a biomarker of infected necrosis

IntroductionInfected pancreatic necrosis (IPN) is a major cause of mortality in acute pancreatitis (AP). Currently, no specific strategies are available to predict the development of IPN. Earlier we reported that persistent down-regulation of HLA-DR increases risk of developing IPN. Altered kynurenine pathway (KP) metabolites showed poor prognosis in sepsis. Here we evaluated the role of HLA-DR and KP in IPN.MethodsPatients with ANP and healthy controls were enrolled. Demographic and clinical parameters were recorded. Circulating interleukin (IL)-8, 6, 1β, 10, Tumor necrosis factor-α were quantified using flowcytometry. Plasma procalcitonin, endotoxin, and KP (tryptophan, kynurenine) concentrations were estimated using ELISA. qRT-PCR was conducted to evaluate mRNA expression of HLA-DR, IL-10, Toll like receptor-4 (TLR-4), and kynurenine-3-monooxygenase (KMO) genes on peripheral blood mononuclear cells. Plasma metabolites were quantified using gas chromatography mass spectrometry (GC-MS/MS). Standard statistical methods were used to compare study groups. Metaboanalyst was used to analyse/visualize the metabolomics data.ResultsWe recruited 56 patients in Cohort-1 (IPN:26,Non-IPN:30), 78 in Cohort-2 (IPN:57,Non-IPN:21), 26 healthy controls. Increased cytokines, endotoxin, and procalcitonin were observed in patients with IPN compared to Non-IPN. HLA-DR and KMO gene expressions were significantly down-regulated in IPN groups, showed positive correlation with one another but negatively correlated with IL-6 and endotoxin concentrations. Increased IDO and decreased plasma tryptophan were observed in IPN patients. Metabolome analysis showed significant reduction in several essential amino acids including tryptophan in IPN patients. Tryptophan, at a concentration of 9 mg/ml showed an AUC of 91.9 (95%CI 86.5–97.4) in discriminating IPN.ConclusionHLA-DR downregulation and KP alteration are related to IPN. The KP metabolite plasma tryptophan can act as a potential biomarker for IPN.     

Helicobacter pylori and serum kynurenine-tryptophan ratio in patients with colorectal cancer

AIM: To evaluate how Helicobacter pylori(H. pylori) is able to evade the immune response and whether it enhances systemic immune tolerance against colorectal cancer.METHODS: This prospective randomized study involved 97 consecutive colorectal cancer patients and 108 cancer-free patients with extra-digestive diseases. Colorectal cancer and cancer-free patients were assigned into subgroups according to H. pylori Ig G seropositivity. Exposure to H. pylori was determined by Ig G seropositivity which was detected by enzyme linked immunoassay(ELISA). Serum neopterin levels were measured by ELISA. Serum tryptophan, kynurenine, and urinary biopterin concentrations were measured by high performance liquid chromatography. Serum nitrite levels were detected spectrophotometrically. Serum indoleamine 2,3-dioxygenase activity was estimated by the kynurenine to tryptophan ratio and by assessing the correlation between serum neopterin concentrations and the kynurenine to tryptophan ratio. The frequencies of increased serum kynurenine to tryptophan ratio of H. pylori seronegative and seropositive colorectal cancer subgroups were estimated by comparing them with the average kynurenine to tryptophan ratio of H. pylori seronegative tumor-free patients.RESULTS: Compared with respective controls, in both H. pylori seronegative and seropositive colorectal cancer patients, while serum tryptophan levels were decreased(controls vs patients; seronegative: 20.37 ± 0.89 μmol/L vs 15.71 ± 1.16 μmol/L, P < 0.05; seropositive: 20.71 ± 0.81 μmol/L vs 14.97 ± 0.79 μmol/L, P < 0.01) the kynurenine to tryptophan ratio was significantly increased(controls vs patients; seronegative: 52.85± 11.85 μmol/mmol vs 78.91 ± 8.68 μmol/mmol, P < 0.01, seropositive: 47.31 ± 5.93 μmol/mmol vs 109.65 ± 11.50 μmol/mmol, P < 0.01). Neopterin concentrations in cancer patients were significantly elevated compared with controls(P < 0.05). There was a significant correlation between serum neopterin levels and kynurenine/tryptophan in control and colorectal cancer patients groups(r s = 0.494, P = 0.0001 and r s= 0.293, P = 0.004, respectively). Serum nitrite levels of H. pylori seropositive cancer cases were significantly decreased compared with seropositive controls(controls vs patients; 26.04 ± 2.39 μmol/L vs 20.41 ± 1.48 μmol/L, P < 0.05) The decrease in the nitrite levels of H. pylori seropositive cancer patients may be attributed to excessive formation of peroxynitrite and other reactive nitrogen species.CONCLUSION: A significantly high kynurenine/tryptophan suggested that H. pylori may support the immune tolerance leading to cancer development, even without an apparent upper gastrointestinal tract disease.