Late-onset endothelin receptor blockade in hypertensive heterozygous REN-2 transgenic rats

Our previous studies in heterozygous Ren-2 transgenic rats (TGR) have shown that early treatment with selective endothelin (ET)(A) receptor blockade is superior to nonselective ET(A/B) receptor blockade. The aim of this study was to evaluate the role of the ET system in male heterozygous TGR with established hypertension (late-onset treatment). TGR and control Hannover Sprague-Dawley (HanSD) rats were fed a high-salt diet and were treated concomitantly with the nonselective ET(A/B) receptor blocker bosentan or the selective ET(A) receptor blocker atrasentan from day 52 of age on. Survival rate was partly increased by bosentan and fully normalized with atrasentan. Bosentan transiently decreased blood pressure (BP), whereas atrasentan significantly reduced BP as early as one week after the start of the treatment. This effect persisted for the whole experimental period. Atrasentan also substantially reduced cardiac hypertrophy, proteinuria, glomerulosclerosis and left ventricle ET-1 content. Bosentan improved and atrasentan almost restored podocyte architecture and reversed changes in podocyte phenotype represented by the expression of CD 10, desmin and vimentin. Our results demonstrate that selective ET(A) receptor blockade has more favorable effects than nonselective ET(A/B) receptor blockade and, unlike observed in homozygous TGR, ET(A) receptor blockade has similar effects in heterozygous rats with established hypertension as in young animals with developing hypertension.     

Endogenous conversion of ω‐6 to ω‐3 polyunsaturated fatty acids in fat‐1 mice attenuated intestinal polyposis by either inhibiting COX‐2/β‐catenin signaling or activating 15‐PGDH/IL‐18

Omega‐3 polyunsaturated fatty acids (ω‐3PUFAs) have inhibitory effects in various preclinical cancer models, but their effects in intestinal polyposis have never been examined. As attempts have been made to use nutritional intervention to counteract colon cancer development, in this study we evaluated the effects of ω‐3 PUFAs on intestinal polyposis in the Apc^Min/+ mouse model. The experimental groups included wild‐type C56BL/6 mice, Apc^Min/+ mice, fat‐1 transgenic mice expressing an n‐3 desaturase to enable ω‐3 PUFA synthesis, and Apc^Min/+ × fat‐1 double‐transgenic mice; all mice were 20 weeks of age. Small intestines were collected for gross and pathologic evaluation, including assessment of polyp number and size, followed by immunohistochemical staining and Western blotting. After administration of various concentrations of ω‐3 PUFAs, PUFA levels were measured in small intestine tissue by GC/MS/MS analysis to compare with PUFA synthesis of between C57BL6 and fat‐1mice. As a result, ω‐3 PUFAs significantly attenuated Apc mutation–induced intestinal polyposis accompanied with significant inhibition of Wnt/β‐catenin signaling, COX‐2 and PGE_2, but induced significant levels of 15‐PGDH. In addition, significant induction of the inflammasome‐related substrates as IL‐1β and IL‐18 and activation of caspase‐1 was observed in Apc^Min/+ × fat‐1 mice. Administration of at least 3 g/60 kg ω‐3 PUFAs was equivalent to ω‐3 PUFAs produced in fat‐1 mice and resulted in significant increase in the expression of IL‐1β, caspase‐3 and IL‐18, as seen in Apc^Min/+ × fat‐1 mice. We conclude that ω‐3PUFAs can prevent intestinal polyp formation by inhibition of Wnt/β‐catenin signaling, but increased levels of 15‐PGDH and IL‐18.     

ESAT-6-specific CD4 T cell responses to aerosol Mycobacterium tuberculosis infection are initiated in the mediastinal lymph nodes

CD4⁺ T cell responses to aerosol Mycobacterium tuberculosis (Mtb) infection are characterized by the relatively delayed appearance of effector T cells in the lungs. This delay in the adaptive response is likely critical in allowing the bacteria to establish persistent infection. Because of limitations associated with the detection of low frequencies of naïve T cells, it had not been possible to precisely determine when and where naïve antigen-specific T cells are first activated. We have addressed this problem by using early secreted antigenic target 6 (ESAT-6)-specific transgenic CD4 T cells to monitor early T cell activation in vivo. By using an adoptive transfer approach, we directly show that T cell priming to ESAT-6 occurs only after 10 days of infection, is initially restricted to the mediastinal lymph nodes, and does not involve other lymph nodes or the lungs. Primed CD4 T cells rapidly differentiated into proliferating effector cells and ultimately acquired the ability to produce IFN-γ and TNF-α ex vivo. Initiation of T cell priming was enhanced by two full days depending on the magnitude of the challenge inoculum, which suggests that antigen availability is a factor limiting the early CD4 T cell response. These data define a key period in the adaptive immune response to Mtb infection.     

Transgenic expression of Helicobacter pylori CagA induces gastrointestinal and hematopoietic neoplasms in mouse

Infection with cagA-positive Helicobacter pylori is associated with gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue (MALT) lymphoma of B cell origin. The cagA-encoded CagA protein is delivered into gastric epithelial cells via the bacterial type IV secretion system and, upon tyrosine phosphorylation by Src family kinases, specifically binds to and aberrantly activates SHP-2 tyrosine phosphatase, a bona fide oncoprotein in human malignancies. CagA also elicits junctional and polarity defects in epithelial cells by interacting with and inhibiting partitioning-defective 1 (PAR1)/microtubule affinity-regulating kinase (MARK) independently of CagA tyrosine phosphorylation. Despite these CagA activities that contribute to neoplastic transformation, a causal link between CagA and in vivo oncogenesis remains unknown. Here, we generated transgenic mice expressing wild-type or phosphorylation-resistant CagA throughout the body or predominantly in the stomach. Wild-type CagA transgenic mice showed gastric epithelial hyperplasia and some of the mice developed gastric polyps and adenocarcinomas of the stomach and small intestine. Systemic expression of wild-type CagA further induced leukocytosis with IL-3/GM-CSF hypersensitivity and some mice developed myeloid leukemias and B cell lymphomas, the hematological malignancies also caused by gain-of-function SHP-2 mutations. Such pathological abnormalities were not observed in transgenic mice expressing phosphorylation-resistant CagA. These results provide first direct evidence for the role of CagA as a bacterium-derived oncoprotein (bacterial oncoprotein) that acts in mammals and further indicate the importance of CagA tyrosine phosphorylation, which enables CagA to deregulate SHP-2, in the development of H. pylori-associated neoplasms.     

联合自杀基因及内皮抑素基因双靶点治疗膀胱癌的实验研究

目的 探讨基因重组腺相关病毒自杀基因及内皮抑素(KS)联合基因治疗膀胱癌的效果.方法 (1)通过重组腺相关病毒(rAAV)-增强绿色荧光蛋白(EGFP)转染膀胱肿瘤T24细胞,来确定rAAV对该细胞的转染情况及转染效率;(2)通过rAAV-胸苷激酶(TK)-核糖体插入位点(IRES)-ES(简称rAAV-TIE)体外转染T24膀胱肿瘤细胞及人脐静脉内皮细胞(HUVEC细胞),应用MTT法、流式细胞仪等方法 来检测其对T24细胞及HUVEC细胞凋亡的诱导作用;(3)构建裸鼠膀胱癌模型,分析rAAV-TIE联合基因治疗膀胱癌的体内效果.结果 (1)rAAV-EGFP转染T24细胞后可以表达携带的外源基因EGFP;(2)rAAV-TK、rAAV-TIE转染T24细胞72 h后,流式细胞仪检测结果 显示,rAAV-TK、rAAV-TIE两组凋亡率分别是34.12%和36.91%,明显高于空病毒转染组[rAAV-多克隆位点(MCS)组](3.08%)和空白对照组(0.84%);(3)瘤内注射rAAV-KS、rAAV-TK、rAAV-TIE大约9 d后,肿瘤生长受到显著抑制,治疗结束后:各组肿瘤的体积分别是:rAAV-Es组(0.75±0.08)cm3、rAAV-TK组(0.71±0.11)cm3、rAAV-r11E组(0.52±0.09)cm3、rAAV-MCS组(1.27±0.13)cm3和空白对照组(1.24±0.17)cm3,除rAAV-ES组与rAAV-TK组间比较差异无统计学意义外,其余组间比较差异均有统计学意义(均P<0.05).结论 体外和体内实验表明rAAV-TIE可有效抑制膀胱癌的血管生成和肿瘤的生长,能够双靶点基因治疗膀胱肿瘤.     

桂枝汤苯丙烯类化合物对APP转基因AD小鼠学习记忆障碍的影响

目的:探讨桂枝汤苯丙烯类化合物(PCGZT)对APP转基因阿尔茨海默病(AD)小鼠模型记忆障碍影响及其部分作用机制。方法:按体重随机将3月龄APP695V717转基因小鼠随机分为模型组,阿司匹林组(20 mg·kg-1·d-1),脑复康组(600 mg·kg-1·d-1),石杉碱甲组(0.3 mg·kg-1·d-1)和PCGZT大、中、小剂量(64.4,32.2,16.1 mg·kg-1·d-1)组,每组10只;另取C57BL/6J小鼠10只作为空白组。各组小鼠每天给药1次,约10月龄时,进行Morris水迷宫实验和跳台实验,测定小鼠脑组织丙二醛(MDA)含量,血清中基质金属蛋白酶-2(MMP-2)和MMP-9含量。结果:与模型组比较,PCGZT可以减少APP转基因AD小鼠跳台反应时间,降低错误期总时间和错误次数,提高安全期总时间(P0.05);PCGZT小剂量组提高APP转基因AD小鼠在Morris迷宫实验中站台象限路程比率(P0.01)和站台象限时间比率(P0.05)。同时,PCGZT可以降低AD小鼠脑MDA含量(P0.05)和血清中MMP-9含量(P0.05),对MMP-2含量无影响。结论:PCGZT能够明显改善APP转基因AD小鼠学习记忆障碍,其作用机制可能涉及多个药物靶点。     

Induction of T-cell activation or anergy determined by the combination of intensity and duration of T-cell receptor stimulation, and sequential induction in an individual cell

It has been shown that anergic T cells have important roles in peripheral tolerance, although the precise mechanism for inducing anergy is still unclear. We analysed the kinetics of anergy induction at an individual cell level by flow cytometry. We first successfully obtained T helper type 1 (Th1) cells that had been made uniform with the level of interferon-gamma (IFN-gamma) production induced by antigen stimulation. We then used these Th1 cells to evaluate the degree of anergy for each Th1 cell treated with an anti-CD3 monoclonal antibody according to the level of IFN-gamma secretion. Our results demonstrate that anergic stimulation could induce both activation and anergy, depending on the duration and intensity of stimulation at the level of an individual cell. Each Th1 cell was first activated and then gradually became anergic depending on the duration of stimulation. The duration of the stimulus required for inducing anergy became shorter as the intensity of stimulation became stronger. We also show that the calcineurin signal controlled the induction of activation or anergy depending on the activity. This study contributes to better understanding of the precise mechanism for inducing T-cell anergy.     

Edible vaccines: current status and future

Edible vaccines hold great promise as a cost-effective, easy-to-administer, easy-to-store, fail-safe and socioculturally readily acceptable vaccine delivery system, especially for the poor developing countries. It involves introduction of selected desired genes into plants and then inducing these altered plants to manufacture the encoded proteins. Introduced as a concept about a decade ago, it has become a reality today. A variety of delivery systems have been developed. Initially thought to be useful only for preventing infectious diseases, it has also found application in prevention of autoimmune diseases, birth control, cancer therapy, etc. Edible vaccines are currently being developed for a number of human and animal diseases. There is growing acceptance of transgenic crops in both industrial and developing countries. Resistance to genetically modified foods may affect the future of edible vaccines. They have passed the major hurdles in the path of an emerging vaccine technology. Various technical obstacles, regulatory and non-scientific challenges, though all seem surmountable, need to be overcome. This review attempts to discuss the current status and future of this new preventive modality.     

Time‐dependent changes in proliferation,DNA damage and clock gene expression in hepatocellular carcinoma and healthy liver of a transgenic mouse model

Hepatocellular carcinoma (HCC) is highly resistant to anticancer therapy and novel therapeutic strategies are needed. Chronotherapy may become a promising approach because it may improve the efficacy of antimitotic radiation and chemotherapy by considering timing of treatment. To date little is known about time‐of‐day dependent changes of proliferation and DNA damage in HCC. Using transgenic c‐myc/transforming growth factor (TGFα) mice as HCC animal model, we immunohistochemically demonstrated Ki67 as marker for proliferation and γ‐H2AX as marker for DNA damage in HCC and surrounding healthy liver (HL). Core clock genes (Per1, Per2, Cry1, Cry2, Bmal 1, Rev‐erbα and Clock) were examined by qPCR. Data were obtained from samples collected ex vivo at four different time points and from organotypic slice cultures (OSC). Significant differences were found between HCC and HL. In HCC, the number of Ki67 immunoreactive cells showed two peaks (ex vivo: ZT06 middle of day and ZT18 middle of night; OSC: CT04 and CT16). In ex vivo samples, the number of γ‐H2AX positive cells in HCC peaked at ZT18 (middle of the night), while in OSC their number remained high during subjective day and night. In both HCC and HL, clock gene expression showed a time‐of‐day dependent expression ex vivo but no changes in OSC. The expression of Per2 and Cry1 was significantly lower in HCC than in HL. Our data support the concept of chronotherapy of HCC. OSC may become useful to test novel cancer therapies.