Plos Med:维生素D不足增加多发性硬化患病风险

<正>近日,来自加拿大麦吉尔大学的研究人员在国际学术期刊plos medicine上发表了一项最新研究进展,他们结合遗传分析和实际观察结果发现低水平的维生素D与多发性硬化发生风险增加有关。多发性硬化是一种可以使人变得非常虚弱,并特定性地针对中枢神经系统白质,导致其脱髓鞘的自身免疫性疾病。这种疾病常见于年龄在20岁到40岁之间的年轻人,到目前为止仍然没有治愈多发性硬化的方法。虽然一些观察证据表明体内低水平的维生素D与多发性硬化发生风险有关,但是由于这些研究中的多发性硬化病人常常同时具有其他可能导致发病风险增加的未知因素,因此很难找到低水平维生素D与多发性     

少突胶质前体细胞分化调控在多发性硬化病理发生中的意义

多发性硬化是一类中枢神经系统炎症性脱髓鞘疾病,其发病原因目前尚未明确。深入地研究该疾病的发生发展机制将为临床预防及治疗提供更有效的帮助。髓鞘是中枢神经系统重要的生理结构,主要发挥保护轴突和加速神经冲动传导的作用。在成年中枢神经系统,髓鞘损伤后可以由少突胶质前体细胞经增殖、迁移和分化而重新形成,即髓鞘再生。然而,在慢性多发性硬化症患者的病灶中,由于少突胶质前体细胞分化障碍,导致髓鞘再生减弱,进而造成轴突损伤和神经元丢失,发生不可逆的神经功能障碍,是进展型多发性硬化发生的重要原因。因此,研究进展型多发性硬化患者病灶中少突胶质前体细胞的分化障碍及其相关信号机制对于临床治疗和药物开发具有重要意义。本综述将着眼于少突胶质前体细胞的分化调控机制,分析其在进展型多发性硬化病理发生中的作用和意义,并讨论了相关的潜在治疗靶点。     

血清IL-16、CCL27及TRAIL与多发性硬化病情严重程度的相关性及其预测价值

摘要 目的：探讨血清白细胞介素-16（IL-16）、CC趋化因子配体27（CCL27）及肿瘤坏死因子相关凋亡诱导配体（TRAIL）与多发性硬化病情严重程度的相关性及其预测价值,为多发性硬化的诊断提供理论依据。方法：以2018年1月-2022年10月本院收治的多发性硬化患者72例为研究对象,依据症状严重程度分为急性发作期（n=40）及缓解期（n=32）,另选取同期于本院接受体检的健康志愿者65例为对照组。以酶联免疫吸附法（ELISA）测定所有研究对象的血清IL-16、CCL27、TRAIL水平。以Spearman相关性分析血清IL-16、CCL27、TRAIL水平与多发性硬化病情严重程度的相关性,绘制受试者特征曲线（ROC）分析血清IL-16、CCL27、TRAIL水平对多发性硬化病情严重程度的预测价值。结果：研究组的血清IL-16、CCL27、TRAIL水平高于对照组（P<0.05）;急性发作期患者的血清IL-16、CCL27、TRAIL水平高于缓解期患者（P<0.05）。Spearman相关性分析显示,血清IL-16、CCL27、TRAIL水平与多发性硬化的病情严重程度呈正相关（r=0.436,0.461,0.447,P<0.05）。ROC曲线分析结果显示,血清IL-16、CCL27、TRAIL水平联合预测多发性硬化病情严重程度的曲线下面积（AUC）为0.939,显著优于各指标单独评估。结论：血清IL-16、CCL27、TRAIL水平与多发性硬化的发生、发展密切相关,早期检测血清IL-16、CCL27、TRAIL水平对多发性硬化病情具有一定的预测价值,且联合预测的价值更高。     

个体化补充维生素D与多发性硬化疾病治疗的探讨

维生素D不仅在骨骼代谢及钙平衡中发挥着重要作用,而且具有免疫调节、抗炎及神经细胞保护功能等。这提示我们,VD在自身免疫性疾病如多发性硬化中可能发挥着重要的作用。流行病学调查及临床数据显示,低VD水平或VD代谢失调是诱发多发性硬化的危险因素之一。另有研究报道,VD血清浓度与多发性硬化的疾病活动和进展呈反相关。但是,这些数据并不是没有争议的,VD在多发性硬化治疗和预防中的作用还有着很多需要回答的问题。现有的以VD补充作为治疗MS措施的临床干预研究中得到的临床数据并不具备得出结论的能力,并且有些数据之间甚至是相互矛盾。     

多发性硬化实验动物模型的研究与应用进展

多发性硬化(multiple sclerosis,MS)是一种中枢神经系统慢性炎症性脱髓鞘疾病,为临床神经系统的疑难重病,基本病理特征包括炎症浸润,原发性脱髓鞘和胶质细胞活化等。其病理过程、发病机制的研究以及治疗药物的筛选和评价都需要合适的动物模型。本文从其发病机制、致病特点与适应范围等方面对MS模型研究进展进行介绍。     

哈佛大学开发“T细胞疫苗”

美国哈佛大学医学部的神经学家David A.Hafler首次开发了对自身免疫疾患有效的T细胞疫苗,并在Bringhanrn and Woman's医院(波士顿)的神经性疾患中心给3名脑脊髓多发性硬化(multiple sclerosis, MS)患者使用了这种疫苗。这是1989年4月中旬在芝加哥召开的美国神经学会上发表的。脑脊髓多发性硬化一旦发病,免疫机能就会突然失常,杀伤T细胞就会破坏脑及被     

细胞自噬在多发性硬化中的作用

多发性硬化(multiple sclerosis,MS)是一种以白质脱髓鞘、胶质细胞增殖、轴突损伤和进行性神经功能障碍为主要特点的中枢神经系统慢性炎症脱髓鞘疾病,其病因和发病机制尚未完全明确。既往在对MS及其动物模型实验性自身免疫性脑脊髓炎的研究中发现了细胞自噬也参与了其发病,涉及到的主要有T淋巴细胞、B淋巴细胞、小胶质细胞、少突胶质细胞、星形胶质细胞、树突状细胞、神经元。因此,本文将对以上细胞自噬在MS中的作用进行综述,以期为研究MS的发病机制和治疗研究提供参考。     

缓解-复发型多发性硬化和化脓性脑膜炎患者IL-12p40、IFN-γ水平的研究

目的:探讨白细胞介素-12p40(IL-12P40)及干扰素-γ(IFN-γ)在缓解-复发型多发性硬化(RRMS)和化脓性脑膜炎(BM)发病中的作用。方法:选取RRMS急性期患者24例,BM8例及作为对照组的非炎性神经系统疾病(NIND)患者12例,应用ELISA法测定受试者血清及脑脊液中IL-12p40、IFN-γ水平。结果:与NIND组相比,RRMS组血清中IL-12p40水平显著下降,IFN-γ水平显著升高,BM组脑脊液中IL-12p40、IFN-γ水平显著升高。结论:IL-12p40、IFN-γ参与了多发性硬化及化脓性脑膜炎发病的免疫病理过程。     

适用于MR成像的多发性硬化大鼠模型的研究进展

多发性硬化(MS)是中青年非外伤性致残的最常见原因,但是MS的发病机制迄今尚不完全明了。核磁共振成像(MRI)是目前诊断、监测MS的重要手段。实验性自身免疫性脑脊髓炎(EAE)是公认的研究人类MS的动物模型,MRI为EAE模型的评估提供直接、客观的影像学依据。理想的EAE大鼠模型不仅有助于开展对MS的防治、发病机理、相关药物开发等多方面的研究,而且为MRI提供合适的研究平台,对MS早期诊断、病情的监测和评价提供重要线索。     

CD8+T细胞在多发性硬化中的致病性作用

多发性硬化是T细胞介导的自身免疫性疾病。先前对它的研究大多集中在CD4 T细胞的致病和调节性作用上,但是,近几年来越来越多的证据表明CD8 T细胞也参与多发性硬化的病理损伤过程。 CD8 T细胞存在于MS病灶部位,髓鞘抗原特异性CD8 T细胞也从MS患者的血液和脑脊液中分离得到,CD8 T细胞通过直接杀伤或释放细胞因子和趋化因子等间接参与MS的病理过程。本文就近几年关于CD8 T细胞在多发性硬化中的致病性作用的研究进展予以介绍。     

A subgenomic segment of Theiler's murine encephalomyelitis virus RNA causes demyelination

The DA strain of Theiler's murine encephalomyelitis virus (TMEV) causes a persistent central nervous system (CNS) infection of mice with a restricted virus gene expression and induces an inflammatory demyelinating disease that is thought to be immune mediated and a model of multiple sclerosis (MS). The relative contribution of virus vis-à-vis the immune system in the pathogenesis of DA-induced white matter disease remains unclear, as is also true in MS. To clarify the pathogenesis of DA-induced demyelination, we used Cre/loxP technology to generate a transgenic mouse that has tamoxifen (Tm)-inducible expression of a subgenomic segment of DA RNA in oligodendrocytes and Schwann cells. Tm-treated young transgenic mice developed progressive weakness leading to death, with abnormalities of oligodendrocytes and Schwann cells and demyelination, but without inflammation, demonstrating that DA virus can play a direct pathogenic role in demyelination. Tm treatment of mice at a later age resulted in milder disease, with evidence of peripheral nerve remyelination and focal fur depigmentation; surviving weak mice had persistent expression of the recombined transgene in the CNS, suggesting that the DA subgenomic segment can cause cellular dysfunction but not death, possibly similar to the situation seen during DA virus persistence. These studies demonstrate that DA RNA or a DA protein(s) is toxic to myelin-synthesizing cells. This Cre/loxP transgenic system allows for spatially and temporally controlled expression of the viral transgene and is valuable for clarifying nonimmune (and immune) mechanisms of demyelination induced by TMEV as well as other viruses.     

Influenza A viral replication is blocked by inhibition of the inositol-requiring enzyme 1 (IRE1) stress pathway

Known therapies for influenza A virus infection are complicated by the frequent emergence of resistance. A therapeutic strategy that may escape viral resistance is targeting host cellular mechanisms involved in viral replication and pathogenesis. The endoplasmic reticulum (ER) stress response, also known as the unfolded protein response (UPR), is a primitive, evolutionary conserved molecular signaling cascade that has been implicated in multiple biological phenomena including innate immunity and the pathogenesis of certain viral infections. We investigated the effect of influenza A viral infection on ER stress pathways in lung epithelial cells. Influenza A virus induced ER stress in a pathway-specific manner. We showed that the virus activates the IRE1 pathway with little or no concomitant activation of the PERK and the ATF6 pathways. When we examined the effects of modulating the ER stress response on the virus, we found that the molecular chaperone tauroursodeoxycholic acid (TUDCA) significantly inhibits influenza A viral replication. In addition, a specific inhibitor of the IRE1 pathway also blocked viral replication. Our findings constitute the first evidence that ER stress plays a role in the pathogenesis of influenza A viral infection. Decreasing viral replication by modulating the host ER stress response is a novel strategy that has important therapeutic implications.     

MyD88-dependent immune activation mediated by human immunodeficiency virus type 1-encoded Toll-like receptor ligands

Immune activation is a major characteristic of human immunodeficiency virus type 1 (HIV-1) infection and a strong prognostic factor for HIV-1 disease progression. The underlying mechanisms leading to immune activation in viremic HIV-1 infection, however, are not fully understood. Here we show that, following the initiation of highly active antiretroviral therapy, the immediate decline of immune activation is closely associated with the reduction of HIV-1 viremia, which suggests a direct contribution of HIV-1 itself to immune activation. To propose a mechanism, we demonstrate that the single-stranded RNA of HIV-1 encodes multiple uridine-rich Toll-like receptor 7/8 (TLR7/8) ligands that induce strong MyD88-dependent plasmacytoid dendritic cell and monocyte activation, as well as accessory cell-dependent T-cell activation. HIV-1-encoded TLR ligands may, therefore, directly contribute to the immune activation observed during viremic HIV-1 infection. These data provide an initial rationale for inhibiting the TLR pathway to directly reduce the chronic immune activation induced by HIV-1 and the associated immune pathogenesis.     

Cell contact-mediated signaling of monocytes by stimulated T cells: a major pathway for cytokine induction

T lymphocytes are currently thought to play a pivotal part in the pathogenesis of chronic inflammatory diseases. However, the mechanism(s) by which they exert their pathogenic effect remain(s) elusive. Contact-mediated signaling of monocytes by stimulated T cells is a potent pro-inflammatory mechanism that triggers massive up-regulation of the pro-inflammatory cytokines interleukin-1 (IL-1) and tumor necrosis factor-a (TNF-alpha) that play an important part in chronic destructive diseases such as rheumatoid arthritis and multiple sclerosis. To date cell-cell contact is the only endogenous mechanism to be described that displays such an activity in monocyte-macrophages which are classically stimulated in vitro by bacterial products such as LPS or non-specific stimuli such as phorbol esters or poorly activated by soluble cytokines such as IFN-gamma. Since direct cellular contact occurs at the inflammatory site, we hypothesized that this mechanism is relevant to the pathogenesis of chronic inflammatory disorders. This review aims at summarizing the state of the art and importance of contact-mediated monocyte activation by stimulated T lymphocytes.     

Initiation and exacerbation of autoimmune demyelination of the central nervous system via virus-induced molecular mimicry: implications for the pathogenesis of multiple sclerosis

Epidemiological studies indicate that infectious agents are important in the pathogenesis of multiple sclerosis (MS). Our previous reports showed that the infection of SJL mice with a nonpathogenic variant of Theiler's murine encephalomyelitis virus (TMEV) engineered to express a naturally occurring Haemophilus influenzae-encoded molecular mimic (HI574-586) of an immunodominant self-myelin proteolipid protein epitope (PLP139-151) induced a rapid-onset demyelinating disease associated with the activation of PLP139-151-specific Th1 responses. The current results extend our previous findings in four critical respects. We show that disease initiation by the H. influenzae mimic is prevented by tolerance to the self PLP139-151 epitope, definitively proving the occurrence of infection-induced molecular mimicry. We demonstrate that the H. influenzae mimic epitope can be processed from the flanking sequences within the native mimic protein. We show that the H. influenzae mimic epitope only induces an immunopathologic self-reactive Th1 response and subsequent clinical disease in the context of the TMEV infection and not when administered in complete Freund's adjuvant, indicating that molecular mimicry-induced disease initiation requires virus-activated innate immune signals. Lastly, we show that the infection of SJL mice with TMEV expressing the H. influenzae mimic can exacerbate a previously established nonprogressive autoimmune disease of the central nervous system. Collectively, these findings illustrate the evolving mechanisms by which virus infections may contribute to both the initiation and exacerbation of autoimmune diseases, and they have important implications for MS pathogenesis.     

Persistent or Slow Viral Infections and Related Diseases

The discovery of persistent transmissible agents by veterinarians has led to striking advances in the infectious cause of neuropathies of human beings. There is evidence for persisting infection in congenital rubella and the herpes group of viruses including cytomegalovirus infections. Hepatitis types A and B are candidates for inclusion in the category of persisting viral infections.The rubeola or measles virus is established as a persistent virus which causes elevated antibodies in the serum and cerebrospinal fluid of many patients with severe demyelinating disease such as subacute sclerosing panencephalitis and multiple sclerosis. Elevated antibodies against vaccinia virus have been found in the cerebrospinal fluid of some patients with multiple sclerosis and neuromyelitis optica, a rare form of multiple sclerosis.     

Theiler's Murine Encephalomyelitis Virus (TMEV)-Induced Demyelination: A Model for Human Multiple Sclerosis

Numerous studies suggest that a viral infection, on the appropriate genetic background, may play an important pathogenetic role in the development of multiple sclerosis (MS). Among the several viral models of demyelination that have been investigated during the past two decades, Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease has emerged as one of the best because, similarly to MS, it is based on a combined viral-immune pathogenesis. This review highlights the following salient features of this model. TMEV-induced demyelinating disease is a chronic process, lasting for the life of the animals. Lesions consist of well-demarcated plaques of demyelination, which are strictly related to the presence of mononuclear cell infiltrates. Myelin degeneration is not due to direct viral cytopathic effects, but is rather dependent on the host immune response. Susceptibility/resistance to the disease is genetically regulated, and multiple genes both in and outside the major histocompatibility complex appear to be involved. The best immunological parameter that correlates with susceptibility is the ability of a murine strain to mount a delayed-type hypersensitivity (DTH) response to one or more viral epitopes. The importance of the DTH response against the virus in the pathogenesis of the disease is supported by the prevalent role of TH1 T-helper cells, known to be responsible for DTH responses, in inflamed CNS tissues. The role of DTH responses in the pathogenesis of demyelination is supported by the presence of numerous macrophages in affected CNS and by a direct relationship between the number of macrophages, their persistence in tissues, and the severity of lesions. Macrophages, in addition, are the main reservoir of the virus in the CNS, and their infectability correlates with susceptibility to the disease process. It is hypothesized that following the DTH response to the virus, activated lymphocytes recruit other inflammatory cells, particularly macrophages, into the infected CNS tissues. These nonspecifically recruited cells would secrete a number of proinflammatory molecules and proteases that would destroy myelin as a “bystander effect.”     

Downregulation of autophagy by herpesvirus Bcl-2 homologs

The critical role of the cellular autophagy pathway in viral infection and pathogenesis has become increasingly apparent. Mounting evidences suggest that viruses have developed different strategies to meticulously modulate intracellular autophagy for their own benefits, thereby either promoting efficient viral replication or facilitating viral persistence. While our understanding of these strategies is still in its incipient stage, recent advances demonstrate that gamma herpesvirus Bcl-2 homolog (vBcl-2), which protects virus-infected cells from apoptosis, also suppresses cellular autophagy pathway through its direct interaction with the autophagy protein Beclin1. Interestingly, vBcl-2 has evolved to harbor the enhanced anti-autophagic activity compared to its host counterpart, suggesting an important role of cellular autophagy in response to viral infection and virus-associated pathogenesis. Thus, a detailed study of vBcl-2-mediated regulation of autophagy signal transduction pathway may lead to a better understanding of not only how virus escapes from host innate immunity but also how autophagy regulates viral infection and environmental stresses.