医学生物高技术研究动态

本文阐述了生物技术的发展背景，生物技术的发展动态，重点论述了生物技术在细菌感染、癌症、艾滋病治疗方面的应用进展，本文最后提出了生物技术研究尚待解决的问题。     

无血清培养细胞HICSF的自分泌生长因子的检测

为了探讨无血清培养细胞ＨＩＣＳＦ的自分泌调控机制，采用ＲＴ－ＰＣＲ技术检测生长因子ｂＦＧＦ，ＴＧＦβ１和细胞因子ＩＬ－６，ＩＬ－８，Ｇ－ＣＳＦ以及细胞因子受体ＩＬ－６Ｒ和ＩＬ－８Ｒ在ＨＩＣＳＦ细胞及其同基因来源的血清培养细胞ＨＩＣ中的表达状况，同时用＾３Ｈ－ＴｄＲ掺入法观察重组ＩＬ－６和ＴＧＦβ１对这２种细胞生长的影响，以观察癌细胞在有血清和无血清培养条件下部分生长因子和细胞因子的表达及反应性差异     

Central IL-1 differentially regulates peripheral IL-6 and TNF synthesis

Centrally given interleukin (IL)-1 is known to induce a rapid rises in blood IL-6. To extend this and to examine the mechanism by which this occurs, the effects of intracerebroventricular (icv) injection of human recombinant IL-1β on mRNA expression of IL-6 and tumour necrosis factor (TNF) in the spleen and liver were examined in rats. Icv injection of IL-1 produced a rapid rise of the tissue mRNA levels of IL-6 and TNF in both organs, prior to and/or in parallel with an increase in their serum levels. Pretreatment with chlorisondamine, a ganglionic blocking agent, inhibited the IL-6 responses, while it had little influence on the TNF responses. The results suggest that brain IL-1 induces peripheral production of IL-6, but not of TNF, through autonomic nervous system activation. Received 27 October 1997; received after revision 15 December 1997; accepted 12 January 1998     

Tumor necrosis factor α in the pathogenesis of cerebral malaria

Physiologically in the brain, cytokines such as tumor necrosis factor-alpha (TN) are released by the immune system and can modulate neurological responses. Conversely, the central nervous system (CNS) is also able to modulate cytokine production. In the case of CNS disorders, cytokine release may be modified. Cerebral malaria (CM) is a complication of Plasmodium falciparum infection in humans and is characterized by a reversible encephalopathy with seizures and loss of consciousness. Central clinical signs are partly due to sequestration of parasitized red blood cells in the brain microvasculature due to interactions between parasite proteins and adhesion molecules. TNF is produced and released by host cells following exposure to various malarial antigens. The increase of TNF release is responsible for the overexpression of adhesion molecules. This article reviews the involvement of TNF in cerebral malaria and the relation with all the processes involved in this pathology. It shows that (i) TNF levels are increased in plasma and brain but with no clear correlation between TNF levels and occurrence and severity of CM; (ii) TNF is responsible for intercellular adhesion molecule-1 upregulation in CM, the relation being less clear for other adhesion molecules; (iii) TNF receptors are upregulated in CM, with TNF receptor 2 (TNFR2) showing a higher upregulation than TNFR1 in vivo; (iv) in murine CM, low doses of TNF seem to protect from CM, whereas excess TNF induces CM and anti-TNF therapies (antibodies, pentoxifylline) did not show any efficiency in protection from CM. Moreover, the involvement of lymphotoxin a, which shares with TNF the same receptors with similar affinity, appears to be an interesting target for further investigation.Received 4 December 2002; received after revision 7 February 2003; accepted 14 February 2003     

Cytokines and proteoglycans

Cytokines play an important regulatory role in the metabolism of proteoglycans. Proteoglycans are found in plasma membranes, but predominantly in the extra-cellular matrix. In the latter they are quantitatively and qualitatively essential components. Especially in a tissue like cartilage without any blood vessels, the cells are dependent on cytokines for the communication among themselves in the extra-cellular matrix and also for communication with the outside world. Various cytokines have been found to be able to penetrate the extra-cellular matrix and inhibit, respectively stimulate the proteoglycan synthesis. Also, the degradation of proteoglycans can be stimulated, respectively inhibited by several cytokines. In addition, some cytokines have been found which regulate the effects of the other cytokines. With respect to proteoglycan metabolism a complex cytokine network is emerging.Furthermore it is becoming increasingly clear that proteoglycans are connected to the cytokine network by their own bioactive functions. First, they possibly possess cytokine activities themselves. Second, they can function as receptors, protectors, inactivators and storage ligands for cytokines. So the proteoglycans are clearly involved in the feedback signalling from the extra-cellular matrix to the cells that are synthesizing this extra-cellular matrix. Together with agonistic or antagonistic cytokines they are involved in the regulation of proteoglycan turnover during balanced or unbalanced metabolism in normal, respectively pathological situations.     

哮喘小鼠骨髓DC细胞因子mRNA的分析

通过体外诱导和扩增小鼠骨髓来源的树突状细胞(DC),研究其中的细胞因子mRNA表达,探讨DC在哮喘中可能的作用机制.为此,利用rmGM-CSF和rmIL-4体外诱导骨髓细胞分化为DC,采用多探针模板的核酸酶保护分析检测骨髓来源的DC中细胞因子mRNA的转录.结果表明,在两种细胞因子的作用下,从骨髓中可以诱导出大量的DC;核酸酶保护分析显示骨髓来源的DC中有IL-13,IL-9和IL-3mRNA的转录,并且哮喘组表达IL-13mRNA和IL-9mRNA的相对水平与对照组相比有明显的差异性,P<0.05;而IL-3mRNA的表达在两组鼠中的表达水平没有差异性,P>0.05.可以认为DC在哮喘的形成和发展中起重要作用,提示了靶向于DC的治疗可能成为哮喘治疗的新目标.     

The imidazoline RX871024 induces death of proliferating insulin-secreting cells by activation of c-jun N-terminal kinase

An insufficient number of insulin-producing β-cells is a major cause of defective control of blood glucose in both type 1 and type 2 diabetes. The aim of this study was to clarify whether the insulinotropic imidazolines can affect the survival of highly proliferating insulin-secreting cells, here exemplified by the MIN6 cell line. Our data demonstrate that RX871024, but not efaroxan, triggered MIN6 cell death and potentiated death induced by a combination of the pro-inflammatory cytokines interleukin-1β, interferon- γ and tumor necrosis factor-α. These effects did not involve changes in nitric oxide production but correlated with stimulation of c-jun N-terminal kinase (JNK) activity and activation of caspases-1, -3, -8 and -9. Our results suggest that the imidazoline RX871024 causes death of highly proliferating insulin-secreting cells, putatively via augmentation of JNK activity, a finding that may impact on the possibility of using compounds of similar activity in the treatment of diabetes. Received 13 December 2007; received after revision 5 February 2008; accepted 6 February 2008     

Mycobacterial lipoarabinomannans modulate cytokine production in human T helper cells by interfering with raft/microdomain signalling

Lipoarabinomannans (LAMs) are major lipoglycans of the mycobacterial envelope and constitute immunodominant epitopes of mycobacteria. In this paper, we show that mannose-capped (ManLAM) and non-mannose- capped (PILAM) mycobacterial lipoglycans insert into T helper cell rafts without apparent binding to known receptors. T helper cells modified by the insertion of PILAM responded to CD3 cross-linking by decreasing type 1 (IL-2 and IFN-) and increasing type 2 (IL-4 and IL-5) cytokine production. Modification by the mannose-capped ManLAMs had similar, but more limited effects on T helper cell cytokine production. When incorporated into isolated rafts, PILAMs modulated membrane-associated kinases in a dose-dependent manner, inducing increased phosphorylation of Src kinases and Cbp/PAG in Th1 rafts, while decreasing phosphorylation of the same proteins in Th2 rafts. Mycobacterial lipoglycans thus modify the signalling machineries of rafts/microdomains in T helper cells, a modification of the membrane organization that eventually leads to an overall enhancement of type 2 and inhibition of type 1 cytokine production.Received 9 September 2004; received after revision 14 October 2004; accepted 11 November 2004A. K. Shabaana and K. Kulangara made equal contributions to this work.