反义锁核酸在转基因小鼠体内阻断乙肝病毒C基因表达

目的 探讨针对乙肝病毒C基因反义锁核酸在转基因小鼠体内阻断病毒基因表达的效果.方法 各实验组经尾静脉给药后,采用real-time PCR、时间分辨免疫荧光技术、免疫组织化学法等技术分别检测血清HBV DNA、HBeAg含量及肝细胞内HBcAg的表达情况.结果 注射锁核酸后,对乙肝病毒核酸的复制和乙肝病毒e抗原的合成均有较强的抑制作用,注射后1、3 和5 d,HBV DNA的平均抑制率分别19.24％、39.20％和44.47％;HBeAg的平均抑制分别为30.71％、51.14％和63.46％;小鼠肝细胞的HBcAg阳性细胞数也较对照组明显减少.结论 针对乙肝病毒C基因的反义锁核酸在转基因小鼠体内能有效抑制病毒基因的复制和表达,提示C基因可作核酸药物治疗的有效靶位.     

Recipient Myd88 Deficiency Promotes Spontaneous Resolution of Kidney Allograft Rejection

The myeloid differentiation protein 88 (MyD88) adapter protein is an important mediator of kidney allograft rejection, yet the precise role of MyD88 signaling in directing the host immune response toward the development of kidney allograft rejection remains unclear. Using a stringent mouse model of allogeneic kidney transplantation, we demonstrated that acute allograft rejection occurred equally in MyD88-sufficient (wild-type [WT]) and MyD88^−/− recipients. However, MyD88 deficiency resulted in spontaneous diminution of graft infiltrating effector cells, including CD11b⁻Gr-1⁺ cells and activated CD8 T cells, as well as subsequent restoration of near-normal renal graft function, leading to long-term kidney allograft acceptance. Compared with T cells from WT recipients, T cells from MyD88^−/− recipients failed to mount a robust recall response upon donor antigen restimulation in mixed lymphocyte cultures ex vivo. Notably, exogenous IL-6 restored the proliferation rate of T cells, particularly CD8 T cells, from MyD88^−/− recipients to the proliferation rate of cells from WT recipients. Furthermore, MyD88^−/− T cells exhibited diminished expression of chemokine receptors, specifically CCR4 and CXCR3, and the impaired ability to accumulate in the kidney allografts despite an otherwise MyD88-sufficient environment. These results provide a mechanism linking the lack of intrinsic MyD88 signaling in T cells to the effective control of the rejection response that results in spontaneous resolution of acute rejection and long-term graft protection.     

葛花解酲方对乙醇性HBV转基因小鼠肝癌癌前病变细胞周期调控因子表达的影响

目的观察葛花解酲方对乙醇性HBV转基因小鼠肝癌癌前病变细胞周期蛋白D1(Cyclin D1)、周期蛋白依赖性激酶4(CDK4)及p27细胞周期调控因子蛋白表达的影响,探讨葛花解酲方阻断肝癌癌前病变的作用机制。方法将24只HBV转基因小鼠适应性饲养1周后,随机分为对照组、模型组、治疗组,每组8只。各组小鼠于22周末进行取材光镜观察肝组织病理学改变并用免疫组织化学法检测Cyclin D1、CDK4及p27KIP1蛋白的表达。结果与模型组比较,给药组肝组织病理形态学得到明显改善;与对照组比较,模型组Cyclin D1和CDK4阳性表达率显著升高(P0.05);与模型组比较,治疗组Cyclin D1和CDK4阳性表达率显著下降(P0.05);与对照组比较,模型组p27KIP1阳性表达率显著降低(P0.05),与模型组比较,治疗组p27KIP1阳性表达率显著升高(P0.05)。结论葛花解酲方可以通过下调癌基因Cyclin D1和CDK4的表达,上调抑癌基因p27KIP1的表达,从而达到保护肝脏损害、逆转肝癌癌前病变的作用。     

From classic to spontaneous and humanized models of multiple sclerosis: Impact on understanding pathogenesis and drug development

Multiple sclerosis (MS), a demyelinating disease of the central nervous system (CNS), presents as a complex disease with variable clinical and pathological manifestations, involving different pathogenic pathways. Animal models, particularly experimental autoimmune encephalomyelitis (EAE), have been key to deciphering the pathophysiology of MS, although no single model can recapitulate the complexity and diversity of MS, or can, to date, integrate the diverse pathogenic pathways. Since the first EAE model was introduced decades ago, multiple classic (induced), spontaneous, and humanized EAE models have been developed, each recapitulating particular aspects of MS pathogenesis. The advances in technologies of genetic ablation and transgenesis in mice of C57BL/6J background and the development of myelin-oligodendrocyte glycoprotein (MOG)-induced EAE in C57BL/6J mice yielded several spontaneous and humanized EAE models, and resulted in a plethora of EAE models in which the role of specific genes or cell populations could be precisely interrogated, towards modeling specific pathways of MS pathogenesis/regulation in MS. Collectively, the numerous studies on the different EAE models contributed immensely to our basic understanding of cellular and molecular pathways in MS pathogenesis as well as to the development of therapeutic agents: several drugs available today as disease modifying treatments were developed from direct studies on EAE models, and many others were tested or validated in EAE. In this review, we discuss the contribution of major classic, spontaneous, and humanized EAE models to our understanding of MS pathophysiology and to insights leading to devising current and future therapies for this disease.     

Programmed cell death 1 (PD-1) regulates the effector function of CD8 T cells via PD-L1 expressed on target keratinocytes

Programmed cell death 1 (PD-1) is an inhibitory molecule expressed by activated T cells. Its ligands (PD-L1 and -L2; PD-Ls) are expressed not only by a variety of leukocytes but also by stromal cells. To assess the role of PD-1 in CD8 T cell-mediated diseases, we used PD-1-knockout (KO) OVA-specific T cell-receptor transgenic (Tg) CD8 T cells (OT-I cells) in a murine model of mucocutaneous graft-versus-host disease (GVHD). We found that mice expressing OVA on epidermal keratinocytes (K14-mOVA mice) developed markedly enhanced GVHD-like disease after transfer of PD-1-KO OT-I cells as compared to those mice transferred with wild-type OT-I cells. In addition, K14-mOVA × OT-I double Tg (DTg) mice do not develop GVHD-like disease after adoptive transfer of OT-I cells, while transfer of PD-1-KO OT-I cells caused GVHD-like disease in a Fas/Fas-L independent manner. These results suggest that PD-1/PD-Ls-interactions have stronger inhibitory effects on pathogenic CD8 T cells than does Fas/Fas-L-interactions. Keratinocytes from K14-mOVA mice with GVHD-like skin lesions express PD-L1, while those from mice without the disease do not. These findings reflect the fact that primary keratinocytes express PD-L1 when stimulated by interferon-γ in vitro. When co-cultured with K14-mOVA keratinocytes for 2 days, PD-1-KO OT-I cells exhibited enhanced proliferation and activation compared to wild-type OT-I cells. In addition, knockdown of 50% PD-L1 expression on the keratinocytes with transfection of PD-L1-siRNA enhanced OT-I cell proliferation. In aggregate, our data strongly suggest that PD-L1, expressed on activated target keratinocytes presenting autoantigens, regulates autoaggressive CD8 T cells, and inhibits the development of mucocutaneous autoimmune diseases.     

Molecular mechanisms regulating CD13‐mediated adhesion

CD13/Aminopeptidase N is a transmembrane metalloproteinase that is expressed in many tissues where it regulates various cellular functions. In inflammation, CD13 is expressed on myeloid cells, is up‐regulated on endothelial cells at sites of inflammation and mediates monocyte/endothelial adhesion by homotypic interactions. In animal models the lack of CD13 alters the profiles of infiltrating inflammatory cells at sites of ischaemic injury. Here, we found that CD13 expression is enriched specifically on the pro‐inflammatory subset of monocytes, suggesting that CD13 may regulate trafficking and function of specific subsets of immune cells. To further dissect the mechanisms regulating CD13‐dependent trafficking we used the murine model of thioglycollate‐induced sterile peritonitis. Peritoneal monocytes, macrophages and dendritic cells were significantly decreased in inflammatory exudates from global CD13^KO animals when compared with wild‐type controls. Furthermore, adoptive transfer of wild‐type and CD13^KO primary myeloid cells, or wild‐type myeloid cells pre‐treated with CD13‐blocking antibodies into thioglycollate‐challenged wild‐type recipients demonstrated fewer CD13^KO or treated cells in the lavage, suggesting that CD13 expression confers a competitive advantage in trafficking. Similarly, both wild‐type and CD13^KO cells were reduced in infiltrates in CD13^KO recipients, confirming that both monocytic and endothelial CD13 contribute to trafficking. Finally, murine monocyte cell lines expressing mouse/human chimeric CD13 molecules demonstrated that the C‐terminal domain of the protein mediates CD13 adhesion. Therefore, this work verifies that the altered inflammatory trafficking in CD13^KO mice is the result of aberrant myeloid cell subset trafficking and further defines the molecular mechanisms underlying this regulation.     

Extreme sarcoplasmic reticulum volume loss and compensatory T-tubule remodeling after Serca2 knockout

Cardiomyocyte contraction and relaxation are controlled by Ca(2+) handling, which can be regulated to meet demand. Indeed, major reduction in sarcoplasmic reticulum (SR) function in mice with Serca2 knockout (KO) is compensated by enhanced plasmalemmal Ca(2+) fluxes. Here we investigate whether altered Ca(2+) fluxes are facilitated by reorganization of cardiomyocyte ultrastructure. Hearts were fixed for electron microscopy and enzymatically dissociated for confocal microscopy and electrophysiology. SR relative surface area and volume densities were reduced by 63% and 76%, indicating marked loss and collapse of the free SR in KO. Although overall cardiomyocyte dimensions were unaltered, total surface area was increased. This resulted from increased T-tubule density, as revealed by confocal images. Fourier analysis indicated a maintained organization of transverse T-tubules but an increased presence of longitudinal T-tubules. This demonstrates a remarkable plasticity of the tubular system in the adult myocardium. Immunocytochemical data showed that the newly grown longitudinal T-tubules contained Na(+)/Ca(2+)-exchanger proximal to ryanodine receptors in the SR but did not contain Ca(2+)-channels. Ca(2+) measurements demonstrated a switch from SR-driven to Ca(2+) influx-driven Ca(2+) transients in KO. Still, SR Ca(2+) release constituted 20% of the Ca(2+) transient in KO. Mathematical modeling suggested that Ca(2+) influx via Na(+)/Ca(2+)-exchange in longitudinal T-tubules triggers release from apposing ryanodine receptors in KO, partially compensating for reduced SERCA by allowing for local Ca(2+) release near the myofilaments. T-tubule proliferation occurs without loss of the original ordered transverse orientation and thus constitutes the basis for compensation of the declining SR function without structural disarrangement.