自然杀伤细胞在肿瘤免疫治疗中的作用

自然杀伤(NK)细胞是人体先天免疫的核心组成部分,是肿瘤细胞免疫治疗和抗体免疫治疗的基础.NK细胞通过直接杀伤作用和释放细胞因子来共同控制肿瘤的生长和转移.目前,已开发出多种利用激活的NK细胞治疗肿瘤的方案.然而,癌症患者的NK细胞功能受损,抗癌能力下降,均限制了NK 细胞的临床疗效 .新的方案通过提高NK细胞的数量和杀伤功能来改善治疗效果. 利用体外长期激活、大规模培养临床使用的NK细胞是达成上述效果的最佳方法之一. 本综述讨论了NK细胞研究背景,NK细胞治疗的现状,尤其是体外培养扩增具有较强功能NK细胞的新方案.     

Development of multiplexed analysis for the photocatalytic activities of nanoparticles in aqueous suspension

A multiplexed assay technique to measure the photocatalytic activity (PCA) of nanoparticles (NPs) in aqueous suspension was developed based on the observation of TiO(2) NPs-photocatalytic oxidation rate of NADH by monitoring the fluorescence intensities. 96 sample solutions of a small volume (<150 μL) could be assayed in a single run without separation of NPs within 15 min. PCA values can be measured with high sensitivity and low experimental uncertainties through the observation at various concentrations of photocatalyst, substrate, aqueous protons and pH buffer ions in a short measurement time.     

Heterologous expression of manganese peroxidase in Aspergillus niger and its effect on phenanthrene removal from soil

A strain of Aspergillus niger, previously isolated from sugarcane bagasse because of its capacity to degrade phenanthrene in soil by solid culture, was used to express a manganese peroxidase gene (mnp1) from Phanerochaete chrysosporium, aiming at increasing its polycyclic aromatic hydrocarbons degradation capacity. Transformants were selected based on their resistance to hygromycin B and the discoloration induced on Poly R-478 dye by the peroxidase activity. The recombinant A. niger SBC2-T3 strain developed MnP activity and was able to remove 95% of the initial phenanthrene (400 ppm) from a microcosm soil system after 17 days, whereas the wild strain removed 72% under the same conditions. Transformation success was confirmed by PCR amplification using gene-specific primers, and a single fragment (1,348 bp long, as expected) of the recombinant mnp1 was amplified in the DNA from transformants, which was absent from the parental strain.     

Development of a chitosan nanofibrillar scaffold for skin repair and regeneration

The final goal of the present study was the development of a 3-D chitosan dressing that would shorten the healing time of skin wounds by stimulating migration, invasion, and proliferation of the relevant cutaneous resident cells. Three-dimensional chitosan nanofibrillar scaffolds produced by electrospinning were compared with evaporated films and freeze-dried sponges for their biological properties. The nanofibrillar structure strongly improved cell adhesion and proliferation in vitro. When implanted in mice, the nanofibrillar scaffold was colonized by mesenchymal cells and blood vessels. Accumulation of collagen fibrils was also observed. In contrast, sponges induced a foreign body granuloma. When used as a dressing covering full-thickness skin wounds in mice, chitosan nanofibrils induced a faster regeneration of both the epidermis and dermis compartments. Altogether our data illustrate the critical importance of the nanofibrillar structure of chitosan devices for their full biocompatibility and demonstrate the significant beneficial effect of chitosan as a wound-healing biomaterial.     

Abrupt telomere losses and reduced end-resection can explain accelerated senescence of Smc5/6 mutants lacking telomerase

The highly conserved Structural Maintenance of Chromosome (SMC) proteins are crucial for the formation of three essential complexes involved in high fidelity chromosome transmission during cell division. Recently, the Smc5/6 complex has been reported to be important for telomere maintenance in yeast and also in cancerous human ALT cells, where it could function in a homologous recombination-based (HR) telomere maintenance pathway. Here, we investigate the possible roles of the budding yeast Smc5/6 complex in maintaining appropriate chromosome end-structures allowing cell survival in absence of telomerase. The results show that cells harbouring mutant alleles of genes encoding Smc5/6-complex proteins rapidly stop growing after telomerase loss. Furthermore, this telomerase-induced growth arrest is much more pronounced as compared to cultures with a functional Smc5/6-complex. Bulk telomere sequence loss is not increased in the mutant cells and the evidence suggests that Smc5/6 slows senescence through a partially HR-independent pathway. We propose that in yeast, the Smc5/6-complex is required for efficient and timely termination of DNA replication and repair at telomeres to avoid stochastic telomere loss during cell division. Consistent with this hypothesis, sequencing of telomeres from telomerase-positive smc5/6 mutant cells revealed a higher frequency of telomere breakage events. Finally, the results also show that on dysfunctional telomeres, the generation of 3'-single stranded DNA is impaired, suggesting that the complex may also participate in the formation of single-stranded overhangs which are thought to be the substrates for telomere repeat replenishment in the absence of telomerase.     

Determination of uremic solutes in biological fluids of chronic kidney disease patients by HPLC assay

During chronic kidney disease (CKD), solutes called uremic solutes, accumulate in blood and tissues of patients. We developed an HPLC method for the simultaneous determination of several uremic solutes of clinical interest in biological fluids: phenol (Pol), indole-3-acetic acid (3-IAA), p-cresol (p-C), indoxyl sulfate (3-INDS) and p-cresol sulfate (p-CS). These solutes were separated by ion-pairing HPLC using an isocratic flow and quantified with a fluorescence detection. The mean serum concentrations of 3-IAA, 3-INDS and p-CS were 2.12, 1.03 and 13.03 μM respectively in healthy subjects, 3.21, 17.45 and 73.47 μM in non hemodialyzed stage 3-5 CKD patients and 5.9, 81.04 and 120.54 μM in hemodialyzed patients (stage 5D). We found no Pol and no p-C in any population. The limits of quantification for 3-IAA, 3-INDS, and p-CS were 0.83, 0.72, and 3.2 μM respectively. The within-day CVs were between 1.23 and 3.12% for 3-IAA, 0.98 and 2% for 3-INDS, and 1.25 and 3.01% for p-CS. The between-day CVs were between 1.78 and 5.48% for 3-IAA, 1.45 and 4.54% for 3-INDS, and 1.19 and 6.36% for p-CS. This HPLC method permits the simultaneous and quick quantification of several uremic solutes for daily analysis of large numbers of samples.     

Molecular regulations governing TREK and TRAAK channel functions

K+ channels with two-pore domain (K2p) form a large family of hyperpolarizing channels. They produce background currents that oppose membrane depolarization and cell excitability. They are involved in cellular mechanisms of apoptosis, vasodilatation, anesthesia, pain, neuroprotection and depression. This review focuses on TREK-1, TREK-2 and TRAAK channels subfamily and on the mechanisms that contribute to their molecular heterogeneity and functional regulations. Their molecular diversity is determined not only by the number of genes but also by alternative splicing and alternative initiation of translation. These channels are sensitive to a wide array of biophysical parameters that affect their activity such as unsaturated fatty acids, intra- and extracellular pH, membrane stretch, temperature, and intracellular signaling pathways. They interact with partner proteins that influence their activity and their plasma membrane expression. Molecular heterogeneity, regulatory mechanisms and protein partners are all expected to contribute to cell specific functions of TREK currents in many tissues.     

Increased endothelial cell-leukocyte interaction in murine schistosomiasis: possible priming of endothelial cells by the disease

Background and Aims

Schistosomiasis is an intravascular parasitic disease associated with inflammation. Endothelial cells control leukocyte transmigration and vascular permeability being modulated by pro-inflammatory mediators. Recent data have shown that endothelial cells primed in vivo in the course of a disease keep the information in culture. Herein, we evaluated the impact of schistosomiasis on endothelial cell-regulated events in vivo and in vitro.

Methodology and Principal Findings

The experimental groups consisted of Schistosoma mansoni-infected and age-matched control mice. In vivo infection caused a marked influx of leukocytes and an increased protein leakage in the peritoneal cavity, characterizing an inflamed vascular and cellular profile. In vitro leukocyte-mesenteric endothelial cell adhesion was higher in cultured cells from infected mice as compared to controls, either in the basal condition or after treatment with the pro-inflammatory cytokine tumor necrosis factor (TNF). Nitric oxide (NO) donation reduced leukocyte adhesion to endothelial cells from control and infected groups; however, in the later group the effect was more pronounced, probably due to a reduced NO production. Inhibition of control endothelial NO synthase (eNOS) increased leukocyte adhesion to a level similar to the one observed in the infected group. Besides, the adhesion of control leukocytes to endothelial cells from infected animals is similar to the result of infected animals, confirming that schistosomiasis alters endothelial cells function. Furthermore, NO production as well as the expression of eNOS were reduced in cultured endothelial cells from infected animals. On the other hand, the expression of its repressor protein, namely caveolin-1, was similar in both control and infected groups.

Conclusion/Significance

Schistosomiasis increases vascular permeability and endothelial cell-leukocyte interaction in vivo and in vitro. These effects are partially explained by a reduced eNOS expression. In addition, our data show that the disease primes endothelial cells in vivo, which keep the acquired phenotype in culture.