Role of inducible nitric oxide synthase-derived nitric oxide in lipopolysaccharide plus interferon-gamma-induced pulmonary inflammation

Exposure of mice to lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma) increases nitric oxide (NO) production, which is proposed to play a role in the resulting pulmonary damage and inflammation. To determine the role of inducible nitric oxide synthase (iNOS)-induced NO in this lung reaction, the responses of inducible nitric oxide synthase knockout (iNOS KO) versus C57BL/6J wild-type (WT) mice to aspirated LPS + IFN-gamma were compared. Male mice (8-10 weeks) were exposed to LPS (1.2 mg/kg) + IFN-gamma (5000 U/mouse) or saline. At 24 or 72 h postexposure, lungs were lavaged with saline and the acellular fluid from the first bronchoalveolar lavage (BAL) was analyzed for total antioxidant capacity (TAC), lactate dehydrogenase (LDH) activity, albumin, tumor necrosis factor-alpha (TNF-alpha), and macrophage inflammatory protein-2 (MIP-2). The cellular fraction of the total BAL was used to determine alveolar macrophage (AM) and polymorphonuclear leukocyte (PMN) counts, and AM zymosan-stimulated chemiluminescence (AM-CL). Pulmonary responses 24 h postexposure to LPS + IFN-gamma were characterized by significantly decreased TAC, increased BAL AMs and PMNs, LDH, albumin, TNF-alpha, and MIP-2, and enhanced AM-CL to the same extent in both WT and iNOS KO mice. Responses 72 h postexposure were similar; however, significant differences were found between WT and iNOS KO mice. iNOS KO mice demonstrated a greater decline in total antioxidant capacity, greater BAL PMNs, LDH, albumin, TNF-alpha, and MIP-2, and an enhanced AM-CL compared to the WT. These data suggest that the role of iNOS-derived NO in the pulmonary response to LPS + IFN-gamma is anti-inflammatory, and this becomes evident over time.     

S-亚硝基-N-乙酰-DL-青霉安对巨噬细胞诱导型一氧化氮合酶的影响

目的 观察S-亚硝基-N-乙酰-DL-青霉胺（SNAP）对RAW 264.7诱导型一氧化氮合酶（iNOS）表达的影响,探讨NO在动脉粥样硬化（炎症）过程中的作用.方法 以RAW 264.7巨噬细胞为研究对象,分为空白对照组、SNAP组,采用不同浓度（30、100、300、400、500μmol/L）的SNAP对巨噬细胞进行干预24 h,应用RT-PCR法检测RAW 264.7巨噬细胞iNOS mRNA的表达,采用Western blotting技术检测iNOS蛋白的表达.结果 与空白对照组比较,不同浓度SNAP（30、100、300、400、500 μmol/L）组iNOS mRNA的表达比空白对照组均明显降低（P＜0.05）,不同浓度SNAP（30、100、300 μmol/L）组iNOS蛋白表达明显低于空白对照组（P＜0.05）.结论 NO可以抑制巨噬细胞自身iNOS mRNA基因转录,降低iNOS的合成而发挥负反馈作用.     

花色素苷诱导小鼠巨噬细胞一氧化氮生成及其机制

目的研究花色素苷对小鼠腹腔巨噬细胞一氧化氮(NO)合成的诱导作用及其机制。方法用CCK-8试剂检测花色素苷对小鼠脾细胞增殖的影响;硝酸盐还原酶法检测小鼠腹腔巨噬细胞NO含量;荧光法检测一氧化氮合酶(NOS)活性;RT-PCR检测iNOS mRNA的表达。结果花色素苷可促进小鼠脾细胞增殖,诱导小鼠腹腔巨噬细胞合成NO,提高NOS活性,其中矢车菊素-3-葡萄糖苷能够诱导iNOS mRNA的表达。结论花色素苷能够促进脾细胞的增殖,诱导小鼠腹腔巨噬细胞合成NO,使巨噬细胞激活,具有一定的免疫调节活性。     

Inhibition of nitric oxide production from lipopolysaccharide-treated RAW 264.7 cells by synthetic flavones: Structure-activity relationship and action mechanism

Recent investigations have shown that certain flavonoids, especially flavone derivatives, inhibit nitric oxide (NO) production by inducible NO synthase (iNOS) in macrophages, which contribute their anti-inflammatory action. For the purpose of finding the optimized chemical structures of flavonoids that inhibit NO production, various A- and B-ring substituted flavones were synthesized and evaluated for their inhibitory activity using lipopolysaccharide-treated RAW 264.7 cells. It was found that the optimal chemical structures were A-ring 5,7-dihydroxyflavones having the B-ring 2',3'-dihydroxy or 3',4'-dihydroxy or 3',4'-hydroxy/methoxy (methoxy/hydroxy) groups. These structurally optimized compounds were revealed to be down-regulators of iNOS induction, but not direct iNOS inhibitors. Of these derivatives that were evaluated, 2',3',5,7-tetrahydroxyflavone and 3',4',5,7-tetrahydroxyflavone (luteolin) showed the strongest inhibition. The IC50 values for these compounds were 19.7 and 17.1 microM, respectively. Therefore, these compounds may have a potential as new anti-inflammatory agents.     

Effect of a selective inducible nitric oxide synthase inhibitor on intraocular nitric oxide production in endotoxin-induced uveitis rabbits: in vivo intraocular microdialysis study

Inducible nitric oxide (NO) synthase (iNOS) is believed to contribute to the pathogenesis of endotoxin-induced uveitis (EIU). In the present study, we investigated the inhibitory effects of N(G)-nitro-L-arginine methyl ester (L-NAME), a non-selective NOS inhibitor, and S,S'-1,4-phenylene-bis(1,2-ethanediyl)bis-isothiourea (PBITU), a potent and selective iNOS inhibitor, on intraocular NO production in EIU rabbits using an in vivo intraocular microdialysis technique. The flare level in the anterior chamber increased from 1h after the injection of 100 micro g/kg lipopolysaccharide (LPS), and continued to increase for 24h. Aqueous humor protein concentrations were significantly increased at 24h after LPS-injection. These changes were significantly reduced by L-NAME (10mg/kg) and PBITU (1mg/kg), but not by D-NAME (10mg/kg). The increase in NO(2)(-) and NO(3)(-) levels in the dialysate induced by LPS was significantly inhibited by L-NAME (10mg/kg) and PBITU (1mg/kg), but not by D-NAME (10mg/kg). These results suggest that activation of iNOS may play a key role in the development of EIU, and selective inhibitors of iNOS may have therapeutic applications in the treatment of EIU.     

Role of nitric oxide produced by constitutive and inducible nitric oxide synthases in the mouse gastric fundus

In the present study, the role of nitric oxide (NO) produced by constitutive and inducible nitric oxide synthases (cNOS and iNOS, resepctively) on the contraction and relaxation of fundus in normal and lipopolysaccharide (LPS)-treated mice was examined. A whole fundic ring isolated from mice pretreated with reserpine was mounted in an organ bath containing Krebs' solution with 0.001 mmol/L atropine. Rings were contracted initially by 5-hydroxytryptamine (5-HT; 0.03 mmol/L) before relaxation was induced using ATP (0.03 mmol/L), ADP (0.03 mmol/L), pentoxifylline (0.002 mmol/L), electrical field stimulation (EFS; 50 V, 1 msec, 50 Hz, 3 min) and L-arginine (0.05 mmol/L). All drugs and EFS induced significant relaxation of isolated rings. The relaxations induced were significantly inhibited by N(G)-nitro-L-arginine methyl ester (L-NAME; 1.0 mmol/L). However, the iNOS inhibitors L-N(6)-(1-iminoethyl) lysine hydrochloride (L-NIL; 1.0 mmol/L) and amino guanidine (AMG; 1.0 mmol/L) had no significant effect on tissue relaxation. Then, the relaxant effects of 0.03 mmol/L ATP were tested on precontracted isolated fundic rings taken from 10 mg/kg LPS-treated animals. The non-selective NOS inhibitor L-NAME (10 mg/kg), the iNOS inhibitors L-NIL (3 mg/kg) and AMG (20 mg/kg) and betamethasone (0.1 mg/kg) were used to examine the role of NO produced by iNOS in the relaxation responses. It was found that the level of contraction induced by 0.03 mmol/L 5-HT in rings isolated from LPS-treated animals was significantly (P < 0.5) less than that in rings from untreated mice. However, precontracted tissues from LPS-treated mice were significantly relaxed by ATP and the relaxation response to ATP was significantly inhibited by L-NIL, ANG and betamethasone, but not by L-NAME. We suggest that, in LPS-treated mice, the production of NO from iNOS produces a reduction in the contractile response, as well as a decrease in NO formation by cNOS, resulting in changes to smooth muscle cell function.     

Inducible nitric oxide synthase as a target for osteoarthritis treatment

Introduction: Inducible nitric oxide synthase (iNOS) is the enzyme responsible for the production of nitric oxide (NO), a major proinflammatory and destructive mediator in osteoarthritis (OA).

Areas covered: This is a comprehensive review of the recent literature on the involvement of iNOS in osteoarthritis and its potential to be used as a target for OA treatment. Evidence from in vitro, in vivo and human studies was systematically collected using medical search engines. Preclinical studies have focused on the effect of direct and indirect iNOS inhibitors in both animal and human tissues. Apart from direct inhibitors, common pharmacological agents, herbal and dietary medicines as well as hyperbaric oxygen, low level laser and low intensity pulsed ultrasound have been shown to exhibit a chondroprotective effect by inhibiting the expression of iNOS.

Expert opinion: Data support the further investigation of iNOS inhibitors for the treatment of OA in human studies and clinical trials. Indirect iNOS inhibitors such as interleukin 1 inhibitors also need to be studied in greater detail. Finally, human studies need to be conducted on the herbal and dietary medicines and on the non-invasive, non-pharmacological treatments.     

New inhibitors of nitric oxide production from the seeds of Myristica fragrans

Six dihydrobenzofuran type neolignans were isolated from the dried ripe seeds of Myristica fragrans Houtt. (family: Myristicaceae) and their chemical structures were identified as licarin B (1), 3′-methoxylicarin B (2), myrisfrageal A (3), isodihydrocainatidin (4), dehydrodiisoeugenol (5), and myrisfrageal B (6), respectively, on the basis of spectroscopic data analyses. Among them, compounds 3 and 6 are new compounds. Compounds 1–6 showed inhibition of nitric oxide production in lipopolysaccharide-activated murine monocyte-macrophage RAW264.7 with IC₅₀ values of 53.6, 48.7, 76.0, 36.0, 33.6, and 45.0 μM, respectively. These values were compared to those of the positive controls, indomethacin and L-N⁶-(1-iminoethyl)-lysine, which have IC₅₀ values of 65.3 and 27.1 μM, respectively. Further compounds 3, 5 and 6 suppressed LPS-induced iNOS mRNA expression in a does-dependent manner in RAW 264.7 cells assayed by real-time RT-PCR. Compounds 3, 5 and 6 may inhibit NO overproduction via inhibition of iNOS mRNA expression. The results provided valuable information for further investigation of compounds 1–6 as anti-inflammatory and chemopreventive agents.     

雪莲提取物对脑缺血再灌注损伤小鼠皮层区一氧化氮合酶亚型表达的影响

目的 探讨雪莲提取物对脑缺血再灌注损伤后小鼠皮层3种一氧化氮合酶(NOS)亚型表达的影响.方法 32只健康雄性ICR小鼠完全随机分为假手术组、生理盐水组、雪莲注射液组和依达拉奉组,每组8只,分别给予生理盐水、雪莲注射液或依达拉奉7d后,制作大脑中动脉阻塞模型,缺血60 min再灌注24h后应用免疫组化染色观察计算缺血皮层区每个高倍镜视野下3种NOS亚型的表达.结果 脑缺血再灌注损伤后24h,生理盐水组小鼠皮层神经元型一氧化氮合酶(nNOS)、诱导型一氧化氮合酶(iNOS)及内皮型一氧化氮合酶(eNOS)表达分别为(14.0±4.8)个/HP、(15.0±5.5)个/HP、(18.2±5.5)个/HP,较假手术组[(2.1±0.8)个/HP,(1.3±0.6)个/HP,(3.3±1.9)个/HP]均明显上调(P均为0.000).雪莲注射液组模型制作后皮层nNOS及iNOS阳性细胞表达分别为(7.5±3.8)个/HP、(7.1±3.7)个/HP,较生理盐水组明显减少(P均为0.000);eNOS阳性细胞表达为(22.3±2.3)个/HP,与生理盐水组比较差异无统计学意义(P=0.072).结论 雪莲提取物通过抑制脑缺血再灌注损伤后nNOS及iNOS表达,从而发挥神经保护作用.     

Putative role of nitric oxide synthase isoforms in the changes of nitric oxide concentration in rat brain cortex and cerebellum following sevoflurane and isoflurane anaesthesia

We have previously observed an increase in nitric oxide (NO) content in rat brain cortex following halothane, sevoflurane or isoflurane anaesthesia. This study was undertaken in order to determine whether isoform-specific nitric oxide synthase (NOS) inhibitors and inducers could modify these increases in NO contents. Rats were subjected to isoflurane and sevoflurane anaesthesia with concomitant administration of neuronal nitric oxide synthase (nNOS) inhibitor 7-Nitro-indazole (7-NI), inducible nitric oxide synthase (iNOS) inhibitor 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) or lipopolysaccharide. NO concentration in different organs was measured by electron paramagnetic resonance (EPR) spectroscopy. 7-NI significantly decreased NO concentration in cerebellum but not in brain cortex, whereas AMT decreased NO in all the organs studied. Anaesthesia significantly increased NO concentration in brain cortex and decreased that in cerebellum. AMT abolished the NO increase in brain cortex. Anaesthesia enhanced the drastic increase in NO concentration in brain cortex after intraventricular lipopolysaccharide administration. Isoflurane was found to inhibit recombinant nNOS and iNOS activities at high concentrations (EC50=20 mM). Our data suggest a putative role for iNOS in the increase in NO levels produced by isoflurane and sevoflurane, whereas nNOS activity is probably inhibited during anaesthesia.     

Perthes病患髋一氧化氮浓度变化的研究

目的 探讨Perthes病和一氧化氮（NO）的关系。方法（1）检测20例Perthes病患侧和健侧髋关节液NO浓度。（2）运用Western blot分析6例Perthes病股头软骨及2例因其他原因病死患儿的正常股骨头软骨诱导型一氧化氮合酶（iNOS)表达。结果（1）Perthes病股骨头软骨中有iNOS表达，而正常股骨头软骨中无iNOS表达。结论Perthes病病变过程中有iNOS表达及NO产生，NO参与了Perthes病的形成、发展。     

香菇多糖对巨噬细胞一氧化氮和一氧化氮合酶活性的影响

目的研究香菇多糖(LTN)诱导巨噬细胞的一氧化氮(NO)生成和一氧化氮合酶(iNOS)的活性,探讨LTN的免疫调节作用机理.方法采用Griess反应和荧光法测定不同剂量的LTN作用小鼠腹腔巨噬细胞后NO的生成量和iNOS活性.观察mRNA转录抑制剂、蛋白质合成抑制剂和iNOS抑制剂对巨噬细胞NO的生成和iNOS活性的影响.结果LTN能使小鼠腹腔巨噬细胞NO生成增加,iNOS活性增高,并呈作用剂量依赖关系.3种抑制剂均能抑制LTN诱导的小鼠腹腔巨噬细胞N0的生成和iNOS活性.结论LTN能刺激小鼠腹腔巨噬细胞提高iNOS活性和NO的生成.提示LTN的免疫调节作用机制可能与LTN刺激巨噬细胞NO生成有关.     

Pharmacological profile of FR260330, a novel orally active inducible nitric oxide synthase inhibitor

In this study, we examined effects of a newly synthesized chemical compound, FR260330, (2E)-3-(4-chlorophenyl)-N-[(1S)-2-oxo-2-{[2-oxo-2-(4-{[6-(trifluoromethyl)-4-pyrimidinyl]oxy}-1-piperidinyl)ethyl]amino}-1-(2-pyridinylmethyl)ethyl]acrylamide on nitric oxide (NO) production in rat splenocytes and human colon cancer cell line, DLD-1 cells. FR260330 inhibited NOx production dose dependently in both cells. In lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) treated murine macrophage cell line, RAW264.7, Western blot analysis with gel filtration chromatography revealed FR260330 might prevent dimerization of inducible nitric oxide synthase (iNOS), but had no effect on the expression of iNOS protein. Furthermore, oral administration of FR260330 reduced NOx production dose dependently in plasma from rats exposed to LPS (IC50=1.6 mg/kg). Meanwhile, higher dose (100 mg/kg) of oral administration of FR260330 did not change mean arterial blood pressure in rats. These results suggest that FR260330 might be a useful therapeutical approach to various inflammatory diseases, in which superoxide or peroxynitrite formed from iNOS-derived NO are involved.     

诱导型一氧化氮合酶在膀胱移行细胞癌中表达的临床意义

目的　探讨诱导型一氧化氮合酶 (iNOS)在膀胱移行细胞癌中表达及与临床病理特征的关系。方法　应用兔抗入iNOS多克隆抗体对 60例膀胱移行细胞癌和 10名正常人膀胱粘膜进行免疫组化染色 ,观察iNOS的表达情况。结果　膀胱移行细胞癌中阳性表达率为 63 .3 % ( 3 8/ 60 ) ,10名正常人膀胱粘膜中无阳性表达。iNOS在肿瘤中表达与患者年龄、性别、肿瘤分级无关 (P >0 .0 5 ) ;但浸润型肿瘤iNOS表达显著高于表浅型 ( P <0 .0 1) ,有淋巴结转移的肿瘤组iNOS表达高于无淋巴结转移组 ( P<0 .0 5 )。结论　iNOS在膀胱移行细胞癌中可能促进了肿瘤的浸润和转移 ,iNOS对膀胱移行细胞癌预后判断和基因治疗具有重要理论意义。     

诱导型一氧化氮合成酶在脑膜瘤中的表达及临床意义

目的 探讨诱导型一氧化氮合成酶(iNOS)在脑膜瘤中的表达和临床意义.方法 采用免疫组织化学SABC法检测iNOS在70例脑膜瘤和20例正常脑膜组织中的表达及与临床病理学特征之间的关系.结果 iNOS阳性物质主要定位于脑膜瘤细胞的胞质,iNOS在20例正常脑膜中均为阴性表达,而在脑膜瘤组织中有不同程度的阳性表达,iNOS阳性表达率为64.29％ (45/70),二者相比差异有统计学意义(P＜0.01).Ⅰ、Ⅱ、Ⅲ级不同分化程度的脑膜瘤组织均有iNOS蛋白阳性表达,且随分化程度和瘤周水肿分级升高逐渐增加,不同级别脑膜瘤各组间差异均有统计学意义(P＜0.05).而iNOS的表达与患者的年龄、性别、肿瘤部位和大小无关(均P＞0.05).结论 iNOS的表达与脑膜瘤细胞的分化程度、血管生成密切相关,可能会作为预测脑膜瘤生物学行为的重要指标之一.     

Inhibition of nitric oxide synthase by antisense techniques: investigations of the roles of NO produced by murine macrophages

1. An antisense approach to block nitric oxide (NO) synthesis was developed, complementing the widely used chemical inhibitors and overcoming problems associated with their use in studying the roles of NO.
2. Murine macrophage cell lines (J774.2) were generated expressing a 500 bp sequence from inducible NO synthase (iNOS) in either the antisense or sense orientation, driven by the SV40 promoter/enhancer region.
3. Messenger RNA derived from the transfected sequences was detected by a specific cDNA probe. Cells expressing sense and antisense iNOS RNA were characterized further.
4. The antisense lines produced 22–97% less NO than the sense lines on stimulation with lipopolysaccharide (LPS) in the range 1 ng ml⁻¹–10 μg ml⁻¹, as determined by nitrite production. One antisense line in particular, A10, expressed substantially less iNOS protein on LPS stimulation as determined by western blot analysis.
5. Adhesion of the antisense line, A10, to cytokine-stimulated murine endothelial cells (sEnd.1 line) was significantly higher than adhesion of the sense lines. There was a negative correlation between the amount of NO produced, as determined by nitrite accumulation, and the level of adhesion of the transfected lines. This indicates an anti-adhesive role of NO, produced by macrophages during the 15 min of the assay, in adhesion to endothelial cells.
6. This novel approach allowed the roles of NO in adhesion to be investigated with the substantial advantage that the contribution of NO produced rapidly by activated macrophages could be studied separately from that produced in a continuous manner by endothelial cells.
7. These lines, and the extension of this approach, will be of great use in dissecting the contributions of NO produced by different cell types to its many potential functions.

     

Differential modification of inflammatory enzymes in J774A.1 macrophages by ochratoxin A alone or in combination with lipopolysaccharide

Ochratoxin A (OTA) is a fungal metabolite with controversial immunomodulatory effects. A prolonged in vivo exposure to the mycotoxin may result in impaired immunity and decreased resistance to infections. In the present study, OTA modulation of lipopolysaccharide (LPS)-induced inflammatory process is described in the macrophagic cell line, J774A.1 in order to better understand the mechanisms underlying OTA immunotoxicity. OTA (30nM-100muM) induces a time and concentration dependent cytotoxic effect, increased when cells were co-stimulated with LPS (100ng/ml), a concentration that alone did not modify the cellular viability. Moreover, OTA (3muM) alone induces a significant increase in cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression, while at the highest concentration (10muM) a reduced expression of both enzymes was shown, consistently with the mycotoxin cytotoxic profile. The role of nuclear factor-kB (NF-kB) in the mycotoxin effect was also demonstrated. Conversely, when cells were co-stimulated with LPS, OTA showed a concentration-dependent reduction of COX-2 and iNOS expression and their respective metabolites (PGE(2) and NO). These results confirm the pro-inflammatory role of OTA by itself, and demonstrate the impaired capability of OTA-treated macrophages to respond properly to noxious stimuli, such as LPS, mimicking the environmental co-exposure to both compounds.     

一氧化氮合酶抑制剂的研究进展

一氧化氮（ｎｉｔｒｉｃｏｘｉｄｅ,ＮＯ）是一种能调节细胞多种功能的信息分子,它参与心血管、外周和中枢神经以及免疫等系统生理过程和生物信号的调节。体内组织中的ＮＯ由ＮＯ合酶（Ｎｉｔｒｉｃｏｘｉｄｅｓｙｎｔｈａｓｅ,ＮＯＳ）催化左旋精氨酸而合成,合成后的ＮＯ迅速跨膜扩散释放。各种调节ＮＯ释放的因素均作用于ＮＯＳ催化的化学反应过程,而体内影响该反应的ＮＯＳ在各组织的表达不同。特异性ＮＯＳ抑制剂通过调控ＮＯ的合成,对ＮＯＳ表达相关的各种疾病的预防和治疗具有重要的临床意义。本文对近年来ＮＯＳ抑制剂的研究进展作一概述。     

Distinct regulation of inner medullary collecting duct nitric oxide production from mice and rats

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