Effect of Exchangeable Ions in Natural and Modified Zeolites on Ag Content,Ag Nanoparticle Formation and Their Antibacterial Activity

To broaden the application of silver nanoparticles (AgNPs), which are well-known antibacterial agents, they are supported on different substrates to prevent aggregation, increase their surface area and antibacterial efficiency, and to be separated from the system more effectively at the end of treatment. To produce nanocomposites that consist of silver nanoparticles on natural and modified zeolites, silver ions (Ag⁺) were loaded onto zeolite (natural, Na-modified, H-modified) and then thermally reduced to AgNPs. The effect of the exchangeable cations in zeolite on Ag⁺ uptake, AgNPs formation, size and morphology was investigated by the TEM, SEM, EDX, XPS, UV-vis, XRD and BET methods. The silver amount in the nanocomposites decreased in the following order Na-modified zeolite > natural zeolite > H-modified zeolite. Microscopic techniques showed formation of AgNPs of 1–14 nm on natural and Na-modified zeolite, while the diameter of metal particles on H-modified zeolite was 12–42 nm. Diffuse reflectance UV-vis and XPS methods revealed the presence of both silver ions and AgNPs in the materials indicating that partial reduction of Ag⁺ ions took place upon heating at 400 °C in air. Additionally, antibacterial properties of the nanocomposites were tested against Escherichia coli, and it was found that Ag–containing composites originating from the Na-modified zeolite demonstrated the highest activity.     

Non-Thermal Plasma Reduction of Ag+ Ions into Silver Nanoparticles in Open Atmosphere under Statistically Optimized Conditions for Biological and Photocatalytic Applications

An environmentally friendly non-thermal DC plasma reduction route was adopted to reduce Ag⁺ ions at the plasma–liquid interface into silver nanoparticles (AgNPs) under statistically optimized conditions for biological and photocatalytic applications. The efficiency and reactivity of AgNPs were improved by statistically optimizing the reaction parameters with a Box–Behnken Design (BBD). The size of the AgNPs was chosen as a statistical response parameter, while the concentration of the stabilizer, the concentration of the silver salt, and the plasma reaction time were chosen as independent factors. The optimized parameters for the plasma production of AgNPs were estimated using a response surface methodology and a significant model p < 0.05. The AgNPs, prepared under optimized conditions, were characterized and then tested for their antibacterial, antioxidant, and photocatalytic potentials. The optimal conditions for these three activities were 3 mM of stabilizing agent, 5 mM of AgNO₃, and 30 min of reaction time. Having particles size of 19 to 37 nm under optimized conditions, the AgNPs revealed a 82.3% degradation of methyl orange dye under UV light irradiation. The antibacterial response of the optimized AgNPs against S. aureus and E. coli strains revealed inhabitation zones of 15 mm and 12 mm, respectively, which demonstrate an antioxidant activity of 81.2%.     

Statistically Optimized Production of Saccharides Stabilized Silver Nanoparticles Using Liquid–Plasma Reduction Approach for Antibacterial Treatment of Water

Various conventional approaches have been reported for the synthesis of nanomaterials without optimizing the role of synthesis parameters. The unoptimized studies not only raise the process cost but also complicate the physicochemical characteristics of the nanostructures. The liquid–plasma reduction with optimized synthesis parameters is an environmentally friendly and low-cost technique for the synthesis of a range of nanomaterials. This work is focused on the statistically optimized production of silver nanoparticles (AgNPs) by using a liquid–plasma reduction process sustained with an argon plasma jet. A simplex centroid design (SCD) was made in Minitab statistical package to optimize the combined effect of stabilizers on the structural growth and UV absorbance of AgNPs. Different combinations of glucose, fructose, sucrose and lactose stabilizers were tested at five different levels (−2, −1, 0, 1, 2) in SCD. The effect of individual and mixed stabilizers on AgNPs growth parameters was assumed significant when p-value in SCD is less than 0.05. A surface plasmon resonance band was fixed at 302 nm after SCD optimization of UV results. A bond stretching at 1633 cm⁻¹ in FTIR spectra was assigned to C=O, which slightly shifts towards a larger wavelength in the presence of saccharides in the solution. The presence of FCC structured AgNPs with an average size of 15 nm was confirmed from XRD and EDX spectra under optimized conditions. The antibacterial activity of these nanoparticles was checked against Staphylococcus aureus and Escherichia coli strains by adopting the shake flask method. The antibacterial study revealed the slightly better performance of AgNPs against Staph. aureus strain than Escherichia coli.     

Interferon-gamma and interleukin-4 reciprocally regulate CD8 expression in CD8+ T cells

The CD8 co-receptor can modulate CD8⁺ T cell function through its contributions to T cell receptor (TCR) binding and signaling. Here we show that IFN-γ and IL-4 exert opposing effects on the expression of CD8α mRNA and surface CD8 protein during CD8⁺ T cell activation. IL-4 caused down-regulation of surface CD8 on ovalbumin (OVA)_257–264-specific TCR-transgenic OT-I CD8⁺ T cells activated with OVA_257–264-coated antigen presenting cells or polyclonal stimuli, and on wild type CD8⁺ T cells activated with polyclonal stimuli. This effect was enhanced in each case when the cells lacked a functional IFN-γ or IFN-γR gene. When WT or IFN-γ-deficient OT-I CD8⁺ T cells were analyzed 9 days after co-injection with control or IL-4-expressing OVA⁺ tumor cells into RAG-2^−/−γc^−/− mice, CD8 levels were highest on WT donor cells from mice that received the control tumor and lowest on IFN-γ-deficient donor cells from mice that received the IL-4-expressing tumor. The latter CD8^low cells displayed markedly impaired binding of OVA_257–264/MHC tetramers and peptide/MHC-dependent degranulation. The data reveal an unexpected role for IFN-γ in tuning the CD8 co-receptor during primary CD8⁺ T cell activation both in vitro and in vivo.     

Resistance to age-dependent thymic atrophy in long-lived mice that are deficient in pregnancy-associated plasma protein A

Pregnancy-associated plasma protein A (PAPPA) is a metalloproteinase that controls the tissue availability of insulin-like growth factor (IGF). Homozygous deletion of PAPPA in mice leads to lifespan extension. Since immune function is an important determinant of individual fitness, we examined the natural immune ecology of PAPPA^−/− mice and their wild-type littermates reared under specific pathogen-free condition with aging. Whereas wild-type mice exhibit classic age-dependent thymic atrophy, 18-month-old PAPPA^−/− mice maintain discrete thymic cortex and medulla densely populated by CD4⁺CD8⁺ thymocytes that are capable of differentiating into single-positive CD4 and CD8 T cells. Old PAPPA^−/− mice have high levels of T cell receptor excision circles, and have bone marrows enriched for subsets of thymus-seeding progenitors. PAPPA^−/− mice have an overall larger pool of naive T cells, and also exhibit an age-dependent accumulation of CD44⁺CD43⁺ memory T cells similar to wild-type mice. However, CD43⁺ T cell subsets of old PAPPA^−/− mice have significantly lower prevalence of 1B11 and S7, glycosylation isoforms known to inhibit T cell activation with normal aging. In bioassays of cell activation, splenic T cells of old PAPPA^−/− mice have high levels of activation antigens and cytokine production, and also elicit Ig production by autologous B cells at levels equivalent to young wild-type mice. These data suggest an IGF-immune axis of healthy longevity. Controlling the availability of IGF in the thymus by targeted manipulation of PAPPA could be a way to maintain immune homeostasis during postnatal development and aging.     

Inhibition of the K+ channel KCa3.1 ameliorates T cell–mediated colitis

The calcium-activated K⁺ channel KCa3.1 plays an important role in T lymphocyte Ca²⁺ signaling by helping to maintain a negative membrane potential, which provides an electrochemical gradient to drive Ca²⁺ influx. To assess the role of KCa3.1 channels in lymphocyte activation in vivo, we studied T cell function in KCa3.1^−/− mice. CD4 T helper (i.e., Th0) cells isolated from KCa3.1^−/− mice lacked KCa3.1 channel activity, which resulted in decreased T cell receptor–stimulated Ca²⁺ influx and IL-2 production. Although loss of KCa3.1 did not interfere with CD4 T cell differentiation, both Ca²⁺ influx and cytokine production were impaired in KCa3.1^−/− Th1 and Th2 CD4 T cells, whereas T-regulatory and Th17 function were normal. We found that inhibition of KCa3.1^−/− protected mice from developing severe colitis in two mouse models of inflammatory bowel disease, which were induced by (i) the adoptive transfer of mouse naïve CD4 T cells into rag2^−/− recipients and (ii) trinitrobenzene sulfonic acid. Pharmacologic inhibitors of KCa3.1 have already been shown to be safe in humans. Thus, if these preclinical studies continue to show efficacy, it may be possible to rapidly test whether KCa3.1 inhibitors are efficacious in patients with inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis.     

PD-1+ memory phenotype CD4+ T cells expressing C/EBPα underlie T cell immunodepression in senescence and leukemia

Although altered T cell function plays a part in immunosenescence, the mechanisms remain uncertain. Here we identify a bona fide age-dependent PD-1⁺ memory phenotype (MP) CD4⁺ T cell subpopulation that hardly proliferates in response to T cell receptor (TCR) stimulation and produces abundant osteopontin at the cost of typical T cell lymphokines. These T cells demonstrate impaired repopulation in Rag2^−/− mice, but a homeostatic proliferation in γ-ray–irradiated mice. These T cells also reveal a unique molecular signature, including a strong expression of C/EBPα normally expressed in myeloid-lineage cells, with diminished c-Myc and cyclin D1. Transduction of Cebpa in regular CD4⁺ T cells inhibited the TCR-mediated proliferation with c-Myc and cyclin D1 repression and caused a striking activation of Spp1 encoding osteopontin along with concomitant repression of T cell lymphokine genes. Although these T cells gradually increase in number with age and become predominant at the senescent stage in normal mice, the generation is robustly accelerated during leukemia. In both conditions, their predominance is associated with the diminution of specific CD4⁺ T cell response. The results suggest that global T cell immunodepression in senescence and leukemia is attributable to the increase in PD-1⁺ MP CD4⁺ T cells expressing C/EBPα.     

The immunodominant myeloperoxidase T-cell epitope induces local cell-mediated injury in antimyeloperoxidase glomerulonephritis

Microscopic polyangiitis is an autoimmune small-vessel vasculitis that often manifests as focal and necrotizing glomerulonephritis and renal failure. Antineutrophil cytoplasmic Abs (ANCAs) specific for myeloperoxidase (MPO) play a role in this disease, but the role of autoreactive MPO-specific CD4⁺ T cells is uncertain. By screening overlapping peptides of 20 amino acids spanning the MPO molecule, we identified an immunodominant MPO CD4⁺ T-cell epitope (MPO_409–428). Immunizing C57BL/6 mice with MPO_409–428 induced focal necrotizing glomerulonephritis similar to that seen after whole MPO immunization, when MPO was deposited in glomeruli. Transfer of an MPO_409–428-specific CD4⁺ T-cell clone to Rag1^−/− mice induced focal necrotizing glomerulonephritis when glomerular MPO deposition was induced either by passive transfer of MPO-ANCA and LPS or by planting MPO_409–428 conjugated to a murine antiglomerular basement membrane mAb. MPO_409–428 also induced biologically active anti-MPO Abs in mice. The MPO_409–428 epitope has a minimum immunogenic core region of 11 amino acids, MPO_415–426, with several critical residues. ANCA-activated neutrophils not only induce injury but lodged the autoantigen MPO in glomeruli, allowing autoreactive anti-MPO CD4⁺ cells to induce delayed type hypersensitivity-like necrotizing glomerular lesions. These studies identify an immunodominant MPO T-cell epitope and redefine how effector responses can induce injury in MPO-ANCA–associated microscopic polyangiitis.     

Design of Green Silver Nanoparticles Based on Primula Officinalis Extract for Textile Preservation

The present study aims to bring an addition to biomass resources valorization for environmental-friendly synthesis of nanoparticles. Thus, the green synthesis of silver nanoparticles (AgNPs) was performed, using a novel and effective reducing agent, Primula officinalis extract. The synthesis was optimized by monitoring the characteristic absorption bands, using UV–Vis spectroscopy, and by evaluating the size and physical stability. The phenolic consumption was established using Folin-Ciocâlteu method (1.40 ± 0.42 mg, representing ~5% from the total amount of poly--phenols) and the antioxidant activity was evaluated using chemiluminescence and TEAC methods. The optimum ratio extract to Ag ions was 1:3, for which the AgNPs presented a zeta potential value of −29.3 ± 1.2 mV and particles size of 5–30 nm. For characterization, EDS and XRD techniques were used, along with microscopy techniques (TEM). The AgNPs dispersions were applied on natural textile samples (cotton and wool), as a novel antimicrobial treatment for textile preservation. The treated fabrics were further characterized in terms of chromatic parameters and antimicrobial effect against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Penicillium hirsutum strains. The high percentages of bacterial reduction, >99%, revealed that the AgNPs produced are a good candidate for textiles preservation against microbial degradation.     

The Kv channel blocker 4-aminopyridine enhances Ag+ uptake: a scanning electrochemical microscopy study of single living cells

We report that silver ion (Ag⁺) uptake is enhanced by 4-aminopyridine (4-AP), a well known voltage-sensitive potassium ion channel (K_v) blocker. Both bacterial (Escherichia coli) and mammalian (3T3 fibroblast) cells were used as model systems. Ag⁺ uptake was monitored with a scanning electrochemical microscope with an amperometric Ag⁺ ion-selective electrode (Ag⁺-ISE) and the respiration rates of E. coli cells were measured by oxygen reduction at an ultramicroelectrode. The results showed that not only the amount but also the rate of silver uptake by the cells increased significantly when 4-AP was added to the solution. For fibroblasts, the Ag⁺ uptake rate was 4.8 × 10⁷ ions per cell per sec without 4-AP compared with 1.0 × 10⁸ ions per cell per sec with 0.2 mM 4-AP. For E. coli cells, the uptake rate was 1.5 × 10⁴ ions per cell per sec without 4-AP vs. 3.5 × 10⁴ ions per cell per sec with 0.5 mM 4-AP and 5.9 × 10⁴ ions per cell per sec with 1 mM 4-AP. Thus, 4-AP might be useful where silver is used as antimicrobial agent to speed its uptake.     

Biogenic Synthesis and Characterization of Antioxidant and Antimicrobial Silver Nanoparticles Using Flower Extract of Couroupita guianensis Aubl.

Couroupita guianensis Aubl. is an important medicinal tree. This tree is rich in various phytochemicals, and is therefore used as a potent antioxidant and antibacterial agent. This plant is also used for the treatment of various diseases. Here, we have improved its medicinal usage with the biosynthesis of silver nanoparticles (AgNPs) using Couroupita guianensis Aubl. flower extract as a reducing and capping agent. The biosynthesis of the AgNPs reaction was carried out using 1 mM of silver nitrate and flower extract. The effect of the temperature on the biosynthesis of AgNPs was premeditated by room temperature (25 °C) and 60 °C. The continuous stirring of the reaction mixture at room temperature for approximately one hour resulted in the successful formation of AgNPs. A development of a yellowish brown color confirmed the formation of AgNPs. The efficacious development of AgNPs was confirmed by the characteristic peaks of UV–Vis, X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy spectra. The biosynthesized AgNPs exhibited significant free radical scavenging activity through a DPPH antioxidant assay. These AgNPs also showed potent antibacterial activity against many pathogenic bacterial species. The results of molecular dynamics simulations also proved the average size of NPs and antibacterial potential of the flower extract. The observations clearly recommended that the green biosynthesized AgNPs can serve as effective antioxidants and antibacterial agents over the plant extract.     

Protein tyrosine phosphatases PTP-1B and TC-PTP play nonredundant roles in macrophage development and IFN-γ signaling

The control of tyrosine phosphorylation depends on the fine balance between kinase and phosphatase activities. Protein tyrosine phosphatase 1B (PTP-1B) and T cell protein tyrosine phosphatase (TC-PTP) are 2 closely related phosphatases known to control cytokine signaling. We studied the functional redundancy of PTP-1B and TC-PTP by deleting 1 or both copies of these genes by interbreeding TC-PTP and PTP-1B parental lines. Our results indicate that the double mutant (tcptp^−/−ptp1b^−/−) is lethal at day E9.5–10.5 of embryonic development with constitutive phosphorylation of Stat1. Mice heterozygous for TC-PTP on a PTP-1B–deficient background (tcptp^+/−ptp1b^−/−) developed signs of inflammation. Macrophages from these animals were highly sensitive to IFN-γ, as demonstrated by increased Stat1 phosphorylation and nitric oxide production. In addition, splenic T cells demonstrated increased IFN-γ secretion capacity. Mice with deletions of single copies of TC-PTP and PTP-1B (tcptp^+/−ptp1b^+/−) exhibited normal development, confirming that these genes are not interchangeable. Together, these data indicate a nonredundant role for PTP-1B and TC-PTP in the regulation of IFN signaling.     

Ligustrum lucidum Leaf Extract-Assisted Green Synthesis of Silver Nanoparticles and Nano-Adsorbents Having Potential in Ultrasound-Assisted Adsorptive Removal of Methylene Blue Dye from Wastewater and Antimicrobial Activity

Present study was conducted to investigate the adsorption and ultrasound-assisted adsorption potential of silver nanoparticles (AgNPs) and silver nanoparticles loaded on chitosan (AgCS composite) as nano-adsorbents for methylene blue (MB) removal. AgNPs were synthesized using leaf extract of Ligustrum lucidum, which were incorporated on the chitosan’s surface for modification. UV–Vis Spectroscopy, FTIR, XRD, SEM, and EDX techniques were used to confirm the synthesis and characterization of nanomaterials. Batch adsorption and sono-adsorption experiments for the removal of MB were executed under optimal conditions; for fitting the experimental equilibrium data, Langmuir and Freundlich’s isotherm models were adopted. In addition, the antimicrobial potential of the AgNPs and AgCS were examined against selected bacterial and fungal strains. UV–Vis spectroscopy confirmed AgNPs synthesis from the leaf extract of L. lucidum used as a reducer, which was spherical as exposed in the SEM analysis. The FTIR spectrum illustrated phytochemicals in the leaf extract of L. lucidum functioning as stabilizing agents around AgNPs and AgCS. Whereas, corresponding crystalline peaks of nanomaterial, including a signal peak at 3 keV indicating the presence of silver, were confirmed by XRD and EDX. The Langmuir model was chosen as an efficient model for adsorption and sono-adsorption, which exposed that under optimum conditions (pH = 6, dye initial concentration = 5 mg L⁻¹, adsorbents dosage = 0.005 g, time = 120 min, US power 80 W), MB removal efficiency of AgNPs was >70%, using ultrasound-assisted adsorption compared to the non-sonicated adsorption. Furthermore, AgNPs exhibited promising antibacterial potential against Staphylococcus aureus with the maximum zone of inhibition (14.67 ± 0.47 mm). It was concluded that the green synthesis approach for the large-scale production of metallic nanoparticles is quite effective and can be recommended for efficient and cost-effective way to eradicate dyes, particularly from textile wastewater.     

A reversion of an IL2RG mutation in combined immunodeficiency providing competitive advantage to the majority of CD8+ T cells

Mutations in the common gamma chain (γ_c, CD132, encoded by the IL2RG gene) can lead to B⁺T⁻NK⁻ X-linked severe combined immunodeficiency, as a consequence of unresponsiveness to γc-cytokines such as interleukins-2, -7 and -15. Hypomorphic mutations in CD132 may cause combined immunodeficiencies with a variety of clinical presentations. We analyzed peripheral blood mononuclear cells of a 6-year-old boy with normal lymphocyte counts, who suffered from recurrent pneumonia and disseminated mollusca contagiosa. Since proliferative responses of T cells and NK cells to γc -cytokines were severely impaired, we performed IL2RG gene analysis, showing a heterozygous mutation in the presence of a single X-chromosome. Interestingly, an IL2RG reversion to normal predominated in both naïve and antigen-primed CD8⁺ T cells and increased over time. Only the revertant CD8⁺ T cells showed normal expression of CD132 and the various CD8⁺ T cell populations had a different T-cell receptor repertoire. Finally, a fraction of γδ⁺ T cells and differentiated CD4⁺CD27⁻ effector-memory T cells carried the reversion, whereas NK or B cells were repeatedly negative. In conclusion, in a patient with a novel IL2RG mutation, gene-reverted CD8⁺ T cells accumulated over time. Our data indicate that selective outgrowth of particular T-cell subsets may occur following reversion at the level of committed T progenitor cells.     

Amorphous–Crystalline Calcium Phosphate Coating Promotes In Vitro Growth of Tumor-Derived Jurkat T Cells Activated by Anti-CD2/CD3/CD28 Antibodies

A modern trend in traumatology, orthopedics, and implantology is the development of materials and coatings with an amorphous–crystalline structure that exhibits excellent biocopatibility. The structure and physico–chemical and biological properties of calcium phosphate (CaP) coatings deposited on Ti plates using the micro-arc oxidation (MAO) method under different voltages (200, 250, and 300 V) were studied. Amorphous, nanocrystalline, and microcrystalline statesof CaHPO₄ and β-Ca₂P₂O₇ were observed in the coatings using TEM and XRD. The increase in MAO voltage resulted in augmentation of the surface roughness R_a from 2.5 to 6.5 µm, mass from 10 to 25 mg, thickness from 50 to 105 µm, and Ca/P ratio from 0.3 to 0.6. The electrical potential (EP) of the CaP coatings changed from −456 to −535 mV, while the zeta potential (ZP) decreased from −53 to −40 mV following an increase in the values of the MAO voltage. Numerous correlations of physical and chemical indices of CaP coatings were estimated. A decrease in the ZP magnitudes of CaP coatings deposited at 200–250 V was strongly associated with elevated hTERT expression in tumor-derived Jurkat T cells preliminarily activated with anti-CD2/CD3/CD28 antibodies and then contacted in vitro with CaP-coated samples for 14 days. In turn, in vitro survival of CD4⁺ subsets was enhanced, with proinflammatory cytokine secretion of activated Jurkat T cells. Thus, the applied MAO voltage allowed the regulation of the physicochemical properties of amorphous–crystalline CaP-coatings on Ti substrates to a certain extent. This method may be used as a technological mechanism to trigger the behavior of cells through contact with micro-arc CaP coatings. The possible role of negative ZP and Ca²⁺ as effectors of the biological effects of amorphous–crystalline CaP coatings is discussed. Micro-arc CaP coatings should be carefully tested to determine their suitability for use in patients with chronic lymphoid malignancies.     

Effects of aging on human leukocytes (part II): immunophenotyping of adaptive immune B and T cell subsets

Immunosenescence results from a continuous deterioration of immune responses resulting in a decreased response to vaccines. A well-described age-related alteration of the immune system is the decrease of de novo generation of T and B cells. In addition, the accumulation of memory cells and loss of diversity in antigen specificities resulting from a lifetime of exposure to pathogens has also been described. However, the effect of aging on subsets of γδTCR⁺ T cells and Tregs has been poorly described, and the efficacy of the recall response to common persistent infections in the elderly remains obscure. Here, we investigated alterations in the subpopulations of the B and T cells among 24 healthy young (aged 19–30) and 26 healthy elderly (aged 53–67) individuals. The analysis was performed by flow cytometry using freshly collected peripheral blood. γδTCR⁺ T cells were overall decreased, while CD4⁺CD8⁻ cells among γδTCR⁺ T cells were increased in the elderly. Helios⁺Foxp3⁺ and Helios⁻Foxp3⁺ Treg cells were unaffected with age. Recent thymic emigrants, based on CD31 expression, were decreased among the Helios⁺Foxp3⁺, but not the Helios⁻Foxp3⁺ cell populations. We observed a decrease in Adenovirus-specific CD4⁺ and CD8⁺ T cells and an increase in CMV-specific CD4⁺ T cells in the elderly. Similarly, INFγ⁺TNFα⁺ double-positive cells were decreased among activated T cells after Adenovirus stimulation but increased after CMV stimulation. The data presented here indicate that γδTCR⁺ T cells might stabilize B cells, and functional senescence might dominate at higher ages than those studied here.

Electronic supplementary material

The online version of this article (doi:10.1007/s11357-015-9829-2) contains supplementary material, which is available to authorized users.     

Silver Nanoparticles Effects on In Vitro Germination,Growth, and Biochemical Activity of Tomato,Radish, and Kale Seedlings

The interactions between nanoparticles and plant cells are still not sufficiently understood, and studies related to this subject are of scientific and practical importance. Silver nanoparticles (AgNPs) are one of the most commonly produced and used nanomaterials. This study aimed to investigate the influence of AgNPs applied at the concentrations of 0, 50, and 100 mg·L⁻¹ during the process of in vitro germination as well as the biometric and biochemical parameters of developed seedlings in three vegetable species: Solanum lycopersicum L. ‘Poranek’, Raphanus sativus L. var. sativus ‘Ramona’, and Brassica oleracea var. sabellica ‘Nero di Toscana’. The application of AgNPs did not affect the germination efficiency; however, diverse results were reported for the growth and biochemical activity of the seedlings, depending on the species tested and the AgNPs concentration. Tomato seedlings treated with nanoparticles, particularly at 100 mg·L⁻¹, had shorter shoots with lower fresh and dry weights and produced roots with lower fresh weight. Simultaneously, at the biochemical level, a decrease in the content of chlorophylls and carotenoids and an increase in the anthocyanins content and guaiacol peroxidase (GPOX) activity were reported. AgNPs-treated radish plants had shorter shoots of higher fresh and dry weight and longer roots with lower fresh weight. Treatment with 50 mg·L⁻¹ and 100 mg·L⁻¹ resulted in the highest and lowest accumulation of chlorophylls and carotenoids in the leaves, respectively; however, seedlings treated with 100 mg·L⁻¹ produced less anthocyanins and polyphenols and exhibited lower GPOX activity. In kale, AgNPs-derived seedlings had a lower content of chlorophylls, carotenoids, and anthocyanins but higher GPOX activity of and were characterized by higher fresh and dry shoot weights and higher heterogeneous biometric parameters of the roots. The results of these experiments may be of great significance for broadening the scope of knowledge on the influence of AgNPs on plant cells and the micropropagation of the vegetable species. Future studies should be aimed at testing lower or even higher concentrations of AgNPs and other NPs and to evaluate the genetic stability of NPs-treated vegetable crops and their yielding efficiency.     

Dendritic cell targeted HIV gag protein vaccine provides help to a DNA vaccine including mobilization of protective CD8+ T cells

To improve the efficacy of T cell–based vaccination, we pursued the principle that CD4⁺ T cells provide help for functional CD8⁺ T cell immunity. To do so, we administered HIV gag to mice successively as protein and DNA vaccines. To achieve strong CD4⁺ T cell immunity, the protein vaccine was targeted selectively to DEC-205, a receptor for antigen presentation on dendritic cells. This targeting helped CD8⁺ T cell immunity develop to a subsequent DNA vaccine and improved protection to intranasal challenge with recombinant vaccinia gag virus, including more rapid accumulation of CD8⁺ T cells in the lung. The helper effect of dendritic cell-targeted protein vaccine was mimicked by immunization with specific MHC II binding HIV gag peptides but not peptides from a disparate Yersinia pestis microbe. CD4⁺ helper cells upon adoptive transfer allowed wild-type, but not CD40^−/−, recipient mice to respond better to the DNA vaccine. The transfer also enabled recipients to more rapidly accumulate gag-specific CD8⁺ T cells in the lung following challenge with vaccinia gag virus. Thus, complementary prime boost vaccination, in which prime and boost favor distinct types of T cell immunity, improves plasmid DNA immunization, including mobilization of CD8⁺ T cells to sites of infection.