Induction of osteoclastogenesis in an in vitro model of Gaucher disease is mediated by T cells via TNF-α

Gaucher disease is a lysosomal storage disorder caused by deficiency of glucocerebrosidase enzymatic activity leading to accumulation of its substrate glucocerebrosidase mainly in macrophages. Skeletal disorder of Gaucher disease is the major cause of morbidity and is highly refractory to enzyme replacement therapy. However, pathological mechanisms of bone alterations in Gaucher disease are still poorly understood. We hypothesized that cellular alteration in Gaucher disease produces a proinflammatory milieu leading to bone destruction through enhancement of monocyte differentiation to osteoclasts and osteoclasts resorption activity. Against this background we decided to investigate in an in vitro chemical model of Gaucher disease, the capacity of secreted soluble mediators to induce osteoclastogenesis, and the mechanism responsible for this phenomena. We demonstrated that soluble factors produced by CBE-treated PBMC induced differentiation of osteoclasts precursors into mature and active osteoclasts that express chitotriosidase and secrete proinflammatory cytokines. We also showed a role of TNF-α in promoting osteoclastogenesis in Gaucher disease chemical model. To analyze the biological relevance of T cells in osteoclastogenesis of Gaucher disease, we investigated this process in T cell-depleted PBMC cultures. The findings suggest that T cells play a role in osteoclast formation in Gaucher disease. In conclusion, our data suggests that in vitro GCASE deficiency, along with concomitant glucosylceramide accumulation, generates a state of osteoclastogenesis mediated in part by pro-resorptive cytokines, especially TNF-α. Moreover, T cells are involved in osteoclastogenesis in Gaucher disease chemical model.     

Highly aggregated antibody therapeutics can enhance the in vitro innate and late-stage T-cell immune responses

Aggregation of biotherapeutics has the potential to induce an immunogenic response. Here, we show that aggregated therapeutic antibodies, previously generated and determined to contain a variety of attributes (Joubert, M. K., Luo, Q., Nashed-Samuel, Y., Wypych, J., and Narhi, L. O. (2011) J. Biol. Chem. 286, 25118-25133), can enhance the in vitro innate immune response of a population of naive human peripheral blood mononuclear cells. This response depended on the aggregate type, inherent immunogenicity of the monomer, and donor responsiveness, and required a high number of particles, well above that detected in marketed drug products, at least in this in vitro system. We propose a cytokine signature as a potential biomarker of the in vitro peripheral blood mononuclear cell response to aggregates. The cytokines include IL-1β, IL-6, IL-10, MCP-1, MIP-1α, MIP-1β, MMP-2, and TNF-α. IL-6 and IL-10 might have an immunosuppressive effect on the long term immune response. Aggregates made by stirring induced the highest response compared with aggregates made by other methods. Particle size in the 2-10 μm range and the retention of some folded structure were associated with an increased response. The mechanism of aggregate activation at the innate phase was found to occur through specific cell surface receptors (the toll-like receptors TLR-2 and TLR-4, FcγRs, and the complement system). The innate signal was shown to progress to an adaptive T-cell response characterized by T-cell proliferation and secretion of T-cell cytokines. Investigating the ability of aggregates to induce cytokine signatures as biomarkers of immune responses is essential for determining their risk of immunogenicity.     

Evaluation of a robotic system for the recovery of peripheral blood mononuclear cells

Investigations into immune responses are often based upon recovery of peripheral blood mononuclear cells (PBMC). To this purpose, the recovery of PBMC by gradient centrifugation is labour-intensive and requires a reasonable level of skill by the laboratory technician. Thus, we set out to determine whether laboratory automation equipment could be used for the recovery of PBMC from blood samples of horses, pigs and cattle, based on the Ficoll-Paque gradient centrifugation technique. Mixing of blood samples with PBS, layering of diluted blood onto Ficoll-Paque gradients, recovery of separated PBMC in RPMI 1640 medium were performed using an automated robotic system, the SBF200 (AM Robotic Systems, Warrington, UK) under laminar air flow conditions. Tubes were tagged with bar codes and manually placed after gradient centrifugation into a tube reader to measure the volume and position of the PBMC layer. The results of the automated procedure compared very well to those of the manual one in terms of percent cell recovery, sterility and cell viability. Also, a high throughput of samples could be implemented: with the integration of cell counting it should be possible for 96 blood samples to be processed, including the production of aliquots, by one person in a day.     

A cell-penetrating helical peptide as a potential HIV-1 inhibitor

The capsid domain of the human immunodeficiency virus type 1 (HIV-1) Gag polyprotein is a critical determinant of virus assembly, and is therefore a potential target for developing drugs for AIDS therapy. Recently, a 12-mer α-helical peptide (CAI) was reported to disrupt immature- and mature-like capsid particle assembly in vitro; however, it failed to inhibit HIV-1 in cell culture due to its inability to penetrate cells. The same group reported the X-ray crystal structure of CAI in complex with the C-terminal domain of capsid (C-CA) at a resolution of 1.7 Å. Using this structural information, we have utilized a structure-based rational design approach to stabilize the α-helical structure of CAI and convert it to a cell-penetrating peptide (CPP). The modified peptide (NYAD-1) showed enhanced α-helicity. Experiments with laser scanning confocal microscopy indicated that NYAD-1 penetrated cells and colocalized with the Gag polyprotein during its trafficking to the plasma membrane where virus assembly takes place. NYAD-1 disrupted the assembly of both immature- and mature-like virus particles in cell-free and cell-based in vitro systems. NMR chemical shift perturbation analysis mapped the binding site of NYAD-1 to residues 169-191 of the C-terminal domain of HIV-1 capsid encompassing the hydrophobic cavity and the critical dimerization domain with an improved binding affinity over CAI. Furthermore, experimental data indicate that NYAD-1 most likely targets capsid at a post-entry stage. Most significantly, NYAD-1 inhibited a large panel of HIV-1 isolates in cell culture at low micromolar potency. Our study demonstrates how a structure-based rational design strategy can be used to convert a cell-impermeable peptide to a cell-permeable peptide that displays activity in cell-based assays without compromising its mechanism of action. This proof-of-concept cell-penetrating peptide may aid validation of capsid as an anti-HIV-1 drug target and may help in designing peptidomimetics and small molecule drugs targeted to this protein.     

Generation, affinity maturation, and characterization of a human anti-human NKG2D monoclonal antibody with dual antagonistic and agonistic activity

In humans, NKG2D is an activating receptor on natural killer (NK) cells and a costimulatory receptor on certain T cells and plays a central role in mediating immune responses in autoimmune diseases, infectious diseases, and cancer. Monoclonal antibodies that antagonize or agonize immune responses mediated by human NKG2D are considered to be of broad and potent therapeutic utility. Nonetheless, monoclonal antibodies to NKG2D that are suitable for clinical investigations have not been published yet. Here, we describe the generation, affinity maturation, and characterization of a fully human monoclonal antibody to human NKG2D. Using phage display technology based on a newly generated naïve human Fab library in phage display vector pC3C followed by a tandem chain shuffling process designed for minimal deviation from natural human antibody sequences, we selected a human Fab, designated KYK-2.0, with high specificity and affinity to human NKG2D. KYK-2.0 Fab blocked the binding of the natural human NKG2D ligands MICA, MICB, and ULBP2 as potently as a commercially available mouse anti-human NKG2D monoclonal antibody in immunoglobulin G (IgG) format. Conversion of KYK-2.0 Fab to IgG1 resulted in subnanomolar avidity for human NKG2D. KYK-2.0 IgG1 was found to selectively recognize defined subpopulations of human lymphocytes known to express NKG2D, that is, the majority of human CD8+, CD16+, and CD56+ cells as well as a small fraction of human CD4+ cells. In solution, KYK-2.0 IgG1 interfered with the cytolytic activity of ex vivo expanded human NK cells. By contrast, immobilized KYK-2.0 IgG1 was found to strongly induce human NK cell activation. The dual antagonistic and agonistic activity promises a wide range of therapeutic applications for KYK-2.0 IgG1 and its derivatives.     

Signaling through toll-like receptor 7/8 induces the differentiation of human bone marrow CD34+ progenitor cells along the myeloid lineage

Toll-like receptors (TLRs) play a key role in pathogen recognition and regulation of the innate and adaptive immune responses. Although TLR expression and signaling have been investigated in blood cells, it is currently unknown whether their bone marrow ancestors express TLRs and respond to their ligands. Here we found that TLRs (e.g. TLR4, TLR7 and TLR8) were expressed by freshly isolated human bone marrow (BM) hematopoietic CD34+ progenitor cells. Incubation of these primitive cells with TLR ligands such as immunostimulatory small interfering RNAs and R848, a specific ligand for TLR7/8, induced cytokine production (e.g. IL1-beta, IL6, IL8, TNF-alpha, GM-CSF). Moreover, TLR7/8 signaling induced the differentiation of BM CD34+ progenitors into cells with the morphology of macrophages and monocytic dendritic precursors characterized by the expression of CD13, CD14 and/or CD11c markers. By contrast, R848 ligand did not induce the expression of glycophorin A, an early marker for erythropoiesis. Collectively, the data indicate for the first time that human BM CD34+ progenitor cells constitutively express functional TLR7/TLR8, whose ligation can induce leukopoiesis without the addition of any exogenous cytokines. Thus, TLR signaling may regulate BM cell development in humans.     

Potent covalent inhibitors of bacterial urease identified by activity-reactivity profiling

Covalent enzyme inhibitors constitute a highly important group of biologically active compounds, with numerous drugs available on the market. Although the discovery of inhibitors of urease, a urea hydrolyzing enzyme crucial for the survival of some human pathogens, is a field of medicinal chemistry that has grown in recent years, covalent urease inhibitors have been rarely investigated until now. Forty Michael acceptor-type compounds were screened for their inhibitory activities against bacterial urease, and several structures exhibited high potency in the nanomolar range. The correlation between chemical reactivity towards thiols and inhibitory potency indicated the most valuable compound — acetylenedicarboxylic acid, with $K_i^1=42.5$ nM and $\text{log}{k}_{\mathit{GSH}}=-2.14$. Molecular modelling studies revealed that acetylenedicarboxylic acid is the first example of highly effective mode of binding based on simultaneous bonding to a cysteine residue and interaction with nickel ions present in the active site. Activity-reactivity profiling of reversible covalent enzyme inhibitors is a general method for the identification of valuable drug candidates.     

SLE患者PBMC凋亡状态及相关基因表达的研究

探讨外周血单个核细胞(PBMC)凋亡及其基因调控在系统性红斑狼疮(systemic lupus erythematosus,SLE)发病机制中的作用.用流式细胞仪(FCM)检测PBMC凋亡百分率及T细胞亚群的凋亡状态;用RT-PCR检测PBMC bcl-2和bax的mRNA表达;用FCM检测凋亡相关基因bcl-2,bax,fas,p53和c-myc的蛋白表达.结果显示,SLE患者PBMC凋亡百分率明显高于正常人,且活动期患者高于非活动期患者.SLE活动期患者CD4+,CD8+T细胞数明显低于正常人;非活动期患者CD8+T细胞数明显低于正常人,而CD4+T细胞数与正常人比较无统计学差异;SLE患者PBMC bcl-2和bax mRNA表达与正常人比较无统计学差异;SLE患者PBMC bcl-2,bax和fas蛋白表达明显高于正常人,p53和c-myc蛋白表达在各组之间无统计学差异.SLE患者PBMC凋亡百分率增高、外周血T细胞亚群的异常及bcl-2,bax和fas蛋白表达增高,在SLE发病机制中可能起了一定的作用.