HIV-1 triggers apoptosis in primary osteoblasts and HOBIT cells through TNFalpha activation

Several HIV-1 infected patients show bone loss and osteopenia/osteoporosis during the course of disease. The mechanisms underlying this degenerative process are largely unsettled and it has not been determined yet whether bone dysfunction is linked to HIV-1-mediated direct and/or indirect effects on osteoblasts/osteoclasts cross-talk regulation. This study investigated the effects of HIV-1(IIIb) and HIV-1(ADA) strains on osteoblasts using the osteoblast-derived cell line (HOBIT) and primary human osteoblasts as cellular models. The challenge of these cell cultures by both HIV-1 strains triggered a significant apoptosis activation unrelated to viral infection, since proviral HIV-1 DNA and supernatant HIV-1 RNA were not detected by real time PCR or b-DNA assays respectively. Under the experimental conditions, even heat-inactivated HIV-1 or cross-linked recombinant gp120 treatment of HOBIT and osteoblasts induced programmed cell death, suggesting that apoptosis is regulated by the interaction between HIV-1 gp120 and cell membrane. The analysis of cell culture supernatants showed a significant up-regulation of TNFalpha, a pleiotropic protein considered an apoptosis inducer in the osteoblast model. In fact, pretreatment of HOBIT and osteoblast cell cultures with anti-TNFalpha polyclonal antibody tackled effectively HIV-1 related induction of cell apoptosis. As a whole, these results indicate that HIV-1 may impair bone mass structure homeostasis by TNFalpha regulated osteoblast apoptosis.     

Placental cytokine and chemokine production in HIV-1-infected women: trophoblast cells show a different pattern compared to cells from HIV-negative women

In utero transmission of HIV-1 has been demonstrated and may account for around 10-20% of all materno-fetal HIV-1 transmission. The possible routes for such transmission are transannexial or transplacental. In both cases, the microenvironment (cytokines and chemokines) at the placental interface could be an important regulatory factor in viral transmission. We therefore performed explant cultures of placental villi, and isolated purified trophoblasts, from term placentae obtained from HIV-1-seropositive and HIV-1-seronegative women in order to assess and compare the cytokine and chemokine secretion profiles using ELISA and semiquantitative RT-PCR. No major differences could be seen in the secretions of cytokines and chemokines at the level of whole placental tissue in HIV-1-positive and HIV-1-negative women. However, variations were observed in the expression of inflammatory cytokines and chemokines from trophoblastic cells, depending on the status of HIV-1 infection of the mothers but not the babies, all of which remained uninfected. The significance of these data is discussed.     

Apoptosis-induced inhibition of CD1d-mediated antigen presentation: different roles for caspases and signal transduction pathways

The stimulation of programmed cell death can either enhance or inhibit antigen presentation by classic major histocompatibility complex molecules. In the current study, we report that the induction of apoptosis by topoisomerase I inhibition or elevation of intracellular ceramide levels substantially impairs CD1d-mediated antigen presentation. In the former case, such a reduction occurred via the regulation of both the p38 mitogen-activated protein kinases and protein kinase C delta signal transduction pathways as well as the caspase cascade, whereas the latter was p38-(but not caspase)-dependent. Confocal microscopic analysis showed an altered intracellular distribution of CD1d following the inhibition topoisomerase I or by an increase in intracellular ceramide levels, that was prevented by p38 and caspase inhibitors. Thus, the induction of apoptosis in antigen presenting cells severely compromises CD1d-mediated antigen presentation by multiple mechanisms.     

Regulatory T cells and chronic immune activation in human immunodeficiency virus 1 (HIV-1)-infected children

The function of CD4⁺ T cells with regulatory activity (T_regs) is the down-regulation of immune responses. This suppressive activity may limit the magnitude of effector responses, resulting in failure to control human immunodeficiency virus 1 (HIV-1) infection, but may also suppress chronic immune activation, a characteristic feature of HIV-1 disease. We evaluated the correlation between viral load, immune activation and T_regs in HIV-1-infected children. Eighty-nine HIV-1-infected children (aged 6–14 years) were included in the study and analysed for HIV-1 plasmaviraemia, HIV-1 DNA load, CD4 and CD8 cell subsets. T_reg cells [CD4⁺ CD25^highCD127^lowforkhead box P3 (FoxP3^high)] and CD8-activated T cells (CD8⁺CD38⁺) were determined by flow cytometry. Results showed that the number of activated CD8⁺CD38⁺ T cells increased in relation to HIV-1 RNA plasmaviraemia (r = 0·403, P < 0·0001). The proportion of T_regs also correlated positively with HIV-1 plasmaviraemia (r = 0·323, P = 0·002), but correlated inversely with CD4⁺ cells (r = −0·312, P = 0·004), thus suggesting a selective expansion along with increased viraemia and CD4⁺ depletion. Interestingly, a positive correlation was found between the levels of T_regs and CD8⁺CD38⁺ T cells (r = 0·305, P = 0·005), and the percentage of T_regs tended to correlate with HIV-1 DNA load (r = 0·224, P = 0·062). Overall, these findings suggest that immune activation contributes to the expansion of T_reg cells. In turn, the suppressive activity of T_regs may impair effector responses against HIV-1, but appears to be ineffective in limiting immune activation.     

成骨细胞分化与信号转导研究进展

成骨细胞在骨的生长、发育及形成过程中起重要作用，其分化受严格调控，通过多种信号途径实现对成骨细胞的定向分化。综述了G蛋白信号调节因子、BMP／Smads、MAPK、PI3-k以及细胞因子等信号通路在成骨细胞定向分化方面的研究进展。     

成骨细胞分化与信号转导研究进展

成骨细胞在骨的生长、发育及形成过程中起重要作用,其分化受严格调控,通过多种信号途径实现对成骨细胞的定向分化。综述了G蛋白信号调节因子、BMP/Smads、MAPK、PI3-k以及细胞因子等信号通路在成骨细胞定向分化方面的研究进展。     

埃兹蛋白参与调控的信号转导通路研究进展

埃兹蛋白（Ezrin）是细胞骨架连接蛋白（Ezrin-Radixin-Moesin,ERM）家族成员之一,主要分布于细胞皮层。Ezrin作为膜蛋白和肌动蛋白连接蛋白,在调控细胞的形态、生长、生存、黏附、增殖和迁徙等生物学功能中发挥重要作用。其作用机制复杂,涉及Rho、PKA、PKC、MAPK及细胞凋亡等多条信号传导通路。因此,研究Ezrin相关的信号转导,对认识疾病的发展及治疗具有重要意义。     

Intracellular and cell-free (infectious) HIV-1 in rectal mucosa.

The intestinal mucosa contains most of the total lymphocyte pool and plays an important role in viral transmission, but only slight attention has been given to the immunological and virological aspects of human immunodeficiency virus-1 (HIV-1) infection at this site. In this study, before initiating or changing antiretroviral therapy, paired blood samples and rectal biopsies (RB) were obtained from 26 consecutive HIV-infected subjects. HIV-1 isolation and biological characterization, DNA, and HIV-1 RNA titration were assessed, as were in vitro tumor necrosis factor-alpha (TNF-alpha) and interleukin-beta (IL-1beta) spontaneous production. The rate of HIV-1 isolation from peripheral blood mononuclear cells (PBMCs) and RBs was 75% and 58%, respectively. All RB-derived isolates were nonsyncytium inducing (NSI), independent of the phenotype of blood-derived isolates. Proviral DNA and detectable HIV-1 RNA levels were measured in 100% and 77% of RBs, respectively. A statistical correlation was observed between HIV-1 DNA and HIV-1 RNA levels in rectal mucosa (P = 0.0075), whereas no correlation was found between these levels in blood samples (P > 0.05). Antiretroviral treatment did not seem to influence HIV-1 detection in RBs. Higher levels of in vitro proinflammmatory cytokine production were found in the RBs of most infected patients when compared with healthy controls. Therefore, the rectal mucosa is an important HIV-1 reservoir that demonstrates a discordant viral evolution with respect to blood. Both the virus type and the mucosa pathway of immunoactive substances might have important implications for therapeutic decision-making and monitoring and could influence the bidirectional transmission of HIV-1 in mucosal surfaces.     

Significant NK cell activation associated with decreased cytolytic function in peripheral blood of HIV-1-infected patients

One of the hallmarks of HIV-1 infection is represented by the finding of massive T cell activation in peripheral blood lymphocytes of infected patients. An impairment of NK cell function during HIV-1 infection is also detected, and is associated with decreased expression of natural cytotoxicity receptors (NCR). In this study we tried to determine whether also NK cells are affected by relevant activation and whether this could be associated with decreased NK cell function. In 18 viremic HIV-1-infected patients, freshly drawn purified peripheral NK cells displayed significant levels of activation with an incomplete pattern (HLA-DR(+)CD69(+)CD25(-)NKp44(-)). Activated (HLA-DR(+)CD69(+)) peripheral NK cells expressed an NCR(dull) phenotype as determined by cytofluorometric analysis in all the patients, and did not derive from a homogeneous/oligoclonal expansion in vivo as analyzed by expression of HLA-specific inhibitory NK cell receptors. As determined by cytotoxicity assays, activated NK cells showed a decreased cytolytic function in HIV-1-infected patients. Thus, the decrease in NK cell function observed during HIV-1 infection is associated not only with decreased NCR expression, but also with significant and incomplete NK cell activation in vivo. These results suggest a consistent continuous involvement of the innate immune response in the failure to control viral replication.     

Defective T-lymphocyte signal transduction and function in leukocyte adhesion deficiency

The lymphocyte function-associated antigen-1 (LFA-1) molecule is a cell surface heterodimeric protein that directly mediates cellular adhesion. However, it remains unclear whether LFA-1 molecules are also involved in transmembrane signaling and in the subsequent regulation of cellular functions. Previous attempts to evaluate this issue have been hampered by (1) the ubiquitous expression of LFA-1 on normal lymphoid cells, (2) the limited availability of assays for cellular activation that are not affected by cellular adhesion, and (3) the difficulties in interpreting studies where anti-LFA-1 mAbs are used to alternatively block or stimulate this antigen. In order to avoid these pitfalls, we first isolated and cloned T lymphocytes from a patient with leukocyte adhesion deficiency (LAD), an inherited disorder in which the defective expression of leukocyte integrins results in the production of LFA-1^– T lymphocytes. Different T-cell lines from this patient and from normal individuals were then stimulated through their T-cell antigen receptor complex and were then tested for three aspects of cellular activation: (1) transmembrane signaling (i.e., phospho-inositide turnover), (2) lymphokine secretion (i.e., release of lymphotoxin), and (3) their capacity to mediate cellular cytotoxicity (using murine anti-CD3-producing hybridoma cells as targets). Using assay systems that did not involve LFA-1-mediated adhesion to antigen-presenting cells or target cells, the T-cell lines from the LAD patient were found to be intrinsically defective in all three of these parameters of T cell activation. However, the defects in transmembrane signaling and lymphokine secretion were relative rather than absolute, as the cells were fully responsive to the maximal receptor stimuli provided by immobilized anti-CD3 mAbs or phytohemagglutinin. Our findings suggest that the leukocyte integrins act not only as cellular adhesion molecules, but also directly affect transmembrane signaling during T-cell activation.     

Intracellular mechanisms of glutaminergic and cholinergic signal transduction in the cerebral cortex

A complex method was used to study the effects of acetylcholine and glutamine on the dynamics of calcium and polyphosphoinositide regulatory system activities over prolonged periods of time in the mammalian cerebral cortex, after exposure to these substances in baseline conditions and in conditions of developing adaptive responses. Adaptive responses were induced by transient hypoxia with oxymetacil as an antioxidant. Agonist stimulation of choline and glutamate receptors produced prolonged calcium and phosphoinositide responses in cortical structures; these had specific characteristics after exposure to glutamate and acetylcholine. During the development of adaptive responses, these changes underwent significant modifications. The functional importance of these effects is discussed. Laboratory for the Regulation of Brain Neuron Function (M. O. Samoilov, Director), I. P. Pavlov Institute of Physiology, St. Petersburg. Translated from Fiziologicheskii Zhurnal im. I. M. Sechenova, Vol. 81, No. 8, pp. 51–56, August, 1995.     

A decreased production of IL12 in vitro is associated with isolation of cytopathic HIV-1 strains in HIV-1-infected patients

The changes in type 1 (IL12, IFNγ, IL2) and type 2 (IL4, IL10) cytokine profiles may be associated with virological parameters of progression of the disease in HIV-1-infected patients. The production of cytokines was studied in LPS + PHA-activated whole-blood culture in HIV-1-infected individuals at different stages of the disease. The association was investigated between IL12p40 and IL12p70 profiles and other cytokines (IFNγ, IL4, IL10), as well as the isolation of cytopathogenic HIV-1 strains. The phenotype of HIV strains was studied by a micromethod based on P4 cell line, allowing detection of cytopathic effects of HIV-1 isolates (syncytium-induction and cell-killing without syncytium induction). The individual variations in IL12p40 and IL12p70 production were limited in the healthy controls. Low values were observed in HIV-1-infected patients. The production of IL12 (p40 and p70) and the IL12p70/IL4 ratio and the IFNγ/IL4 ratio were significantly lower in patients with cytopathic isolates compared with patients with noncytopathic isolates, and a correlation was obtained between the values of IL12 (IL12p40 and IL12p70) and those of IFNγ/IL4 ratio. There was no increase in the secretion of IL4 and IL10 in patients with cytopathic strains compared with other patients. The results indicate a decreased production of type 1 cytokines (IL12, IFNγ) in the presence of a relatively preserved production of type 2 cytokines (IL4, IL10) in HIV-1-infected patients. In conclusion, the defect of production of IL12 by whole blood is associated with virological correlates of progression of HIV-1 disease. J. Med. Virol. 55:209–214, 1998. © 1998 Wiley-Liss, Inc.     

Activation of HIV-1-specific immune responses to an HIV-1 vaccine constructed from a replication-defective adenovirus vector using various combinations of immunization protocols

We constructed a recombinant replication defective adenovirus vector containing the env gene (Ad-Bal) derived from macrophage-trophic HIV-1 (HIV-1 Bal). We then immunized mice with this vector using several administration routes and protocols, and examined the immune response. When the Ad-Bal viral vector (over 1 x 10(7) pfu) was injected subcutaneously, both humoral and cell-mediated immunities were induced. However, immune response induced by the Ad-Bal vector alone was weaker than that induced by the recombinant vaccinia viral vector. We then employed the following three immunization protocols: (l) DNA vaccination followed by immunization with the Ad-Bal; (2) vaccination using the Ad-Bal vector followed by DNA vaccination; and (3) DNA vaccination followed by Ad-Bal infection and passive transfer of dendritic cells (DCs) infected with the Ad-Bal. Among the three protocols, the last gave the strongest humoral and cell-mediated immunity. These results suggest that the combination of DNA vaccination, Ad-Bal vector infection and passive transfer of Ad-Bal-infected DCs can induce strong immunity against HIV-1 Bal.     

慢性心力衰竭的细胞信号转导机制

慢性心力衰竭（chronicheartfailure，CHF）是指各种原因引起心脏泵功能受损，致使心输出量减少，不能满足机体组织代谢需要，并出现心室充盈压升高、体（肺）循环淤血的临床综合征。近年来随着人口老龄化的出现，以及冠心病急性心肌梗塞死亡率的下降，CHF的发病率呈上升趋势，在美国每年有50万人发生心力衰竭’‘’。CHF严重影响老年人生活质量，是发达国家患病率和死亡率最高的疾病之一。CHF发生与发展过程中，多种基因、生理和环境因素共同作用，造成与心肌收缩蛋白功能和兴奋．收缩耦联相关的分子发生变化，如肌球蛋白头部CaZ”－…     

G蛋白参与C1q／C1qR系统介导的信号转导

ａｇｇ－Ｃ１ｑ可抑制人Ｔ细胞系Ｊｕｒｋａｔ和Ｍψ系Ｕ９３７细胞受霍乱毒素刺激的（ｃＡＭＰ）ｉ增高，而百日咳毒素能遏止人Ｂ细胞系Ｒａｊｉ细胞ａｇｇ－Ｃ１ｑ诱导的（ｃＡＭＰ）ｉ升高和Ｃ１ｑＲ交联所促成的磷脂酰肌醇水解。表明：Ｇ蛋白介入了Ｃ１ｑ／Ｃ１ｑＲ系统介导的信号转导途径。     

Evolution of transmitted HIV-1 drug resistance in HIV-1-infected patients in Italy from 2000 to 2010

Prevalence and predictors of transmitted drug resistance (TDR), defined as the presence of at least one WHO surveillance drug resistance mutation (SDRM), were investigated in antiretroviralna?ve HIV-1-infected patients, with a genotypic resistance test (GRT) performed ≤6 months before starting cART between 2000 and 2010. 3163 HIV-1 sequences were selected (69% subtype B). Overall, the prevalence of TDR was 12% (13.2% subtype B, 9% non-B). TDR significantly declined overall and for the single drug classes. Older age independently predicted increased odds of TDR, whereas a more recent GRT, a higher HIV-RNA and C vs. B subtype predicted lower odds of TDR.     

诱导HO-1基因表达的信号通路

血红素氧合酶（HO）的诱导型HO-1与其催化血红素降解生成的产物胆红素和CO一道，组成了机体重要的内源性保护系统，广泛参与抗炎与多种急慢性氧化应激损伤。多种理化因素通过不同的细胞内信号转导通路诱导HO-1的表达，这些信号通路涉及丝裂原活化蛋白激酶（MAPKs）、蛋白激酶C(PKC)、cAMP依赖的蛋白激酶A(PKA)、cGMP依赖蛋白激酶G（PKG）、酪氨酸蛋白激酶（TPK）、蛋白磷酸酶（PPs）、磷脂酰肌醇（-3）激酶（PI3K）/Akt     

巨噬细胞移动抑制因子的信号转导研究进展

巨噬细胞移动抑制因子(MIF)是一种重要的多功能细胞因子,在机体中分布广泛,可能参与了机体多种病理生理反应,其信号转导机制复杂而广泛,主要有激活细胞外信号调节激酶1/2(ERK1/2)信号转导途径、NF-κB途径,Jab 1途径等;与众多自身免疫疾病密切相关。     

CD4+ T cells from HIV-1-infected patients recognize wild-type and mutant human immunodeficiency virus-1 protease epitopes

Human immunodeficiency virus (HIV)-1 protease is a known target of CD8+ T cell responses, but it is the only HIV-1 protein in which no fully characterized HIV-1 protease CD4 epitopes have been identified to date. We investigated the recognition of HIV-1 protease by CD4+ T cells from 75 HIV-1-infected, protease inhibitor (PI)-treated patients, using the 5,6-carboxyfluorescein diacetate succinimidyl ester-based proliferation assay. In order to identify putative promiscuous CD4+ T cell epitopes, we used the TEPITOPE algorithm to scan the sequence of the HXB2 HIV-1 protease. Protease regions 4-23, 45-64 and 73-95 were identified; 32 sequence variants of the mentioned regions, encoding frequent PI-induced mutations and polymorphisms, were also tested. On average, each peptide bound to five of 15 tested common human leucocyte antigen D-related (HLA-DR) molecules. More than 80% of the patients displayed CD4+ as well as CD8+ T cell recognition of at least one of the protease peptides. All 35 peptides were recognized. The response was not associated with particular HLA-DR or -DQ alleles. Our results thus indicate that protease is a frequent target of CD4+ along with CD8+ proliferative T cell responses by the majority of HIV-1-infected patients under PI therapy. The frequent finding of matching CD4(+) and CD8+ T cell responses to the same peptides may indicate that CD4+ T cells provide cognate T cell help for the maintenance of long-living protease-specific functional CD8+ T cells.