Kulachart Jangpatarapongsa

Plasmodium vivax parasites alter the balance of myeloid and plasmacytoid dendritic cells and the induction of regulatory T cells

Immunity induced by Plasmodium vivax infections leads to memory T‐cell recruitment and activation during subsequent infections. Here, we investigated the role of regulatory T cells (Treg) in coordination with the host immune response during P. vivax infection. Our results showed a significant increase in the percentage of FOXP3+ Treg, IL‐10‐secreting Type I Treg (Tr1) and IL‐10 levels in patients with acute P. vivax infection as compared with those found in either naïve or immune controls. The concurrent increase in the Treg population could also be reproduced in vitro using peripheral blood mononuclear cells from naïve controls stimulated with crude antigens extracted from P. vivax‐infected red blood cells. Acute P. vivax infections were associated with a significant decrease in the numbers of DC, indicating a general immunosuppression during P. vivax infections. However, unlike P. falciparum infections, we found that the ratio of myeloid DC (MDC) to plasmacytoid DC (PDC) was significantly lower in acute P. vivax patients than that of naïve and immune controls. Moreover, the reduction in PDC may be partly responsible for the poor antibody responses during P. vivax infections. Taken together, these results suggest that P. vivax parasites interact with DC, which alters the MDC/PDC ratio that potentially leads to Treg activation and IL‐10 release.

Detection of Vibrio cholerae using the intrinsic catalytic activity of a magnetic polymeric nanoparticle.

A novel and sensitive magnetic polymeric nanoparticle (MPNP)-polymerase chain reaction-colorimetry (magneto-PCR-colorimetry) technique was developed for detection of Vibrio cholerae ( V. cholerae ). The technique involved an amplification of V. cholerae DNA on the surface of an MPNP and then employed the intrinsic catalytic activity of the MPNP to detect the target gene by colorimetry. An amino-modified forward primer was covalently labeled onto the MPNP surface which would bind to PCR product during PCR cycling. By employing the catalytic activity of the MPNP, the analysis of PCR product bound MPNP yielded a sensitivity of 10(3) CFU/mL of V. cholerae in buffer system within 4 h. The specificity and efficiency of the technique were investigated by using various bacterial DNAs in drinking and tap water.

Immune response to Plasmodium vivax has a potential to reduce malaria severity.

Plasmodium falciparum infection causes transient immunosuppression during the parasitaemic stage. However, the immune response during simultaneous infections with both P. vivax and P. falciparum has been investigated rarely. In particular, it is not clear whether the hosts immune response to malaria will be different when infected with a single or mixed malaria species. Phenotypes of T cells from mixed P. vivax–P. falciparum (PV‐PF) infection were characterized by flow cytometry, and anti‐malarial antibodies in the plasma were determined by an enzyme‐linked immunosorbent assay. We found the percentage of CD3+δ2+‐T cell receptor (TCR) T cells in the acute‐mixed PV‐PF infection and single P. vivax infection three times higher than in the single P. falciparum infection. This implied that P. vivax might lead to the host immune response to the production of effector T killer cells. During the parasitaemic stage, the mixed PV‐PF infection had the highest number of plasma antibodies against both P. vivax and P. falciparum. Interestingly, plasma from the group of single P. vivax or P. falciparum malaria infections had both anti‐P. vivax and anti‐P. falciparum antibodies. In addition, antigenic cross‐reactivity of P. vivax or P. falciparum resulting in antibodies against both malaria species was shown in the supernatant of lymphocyte cultures cross‐stimulated with either antigen of P. vivax or P. falciparum. The role of δ2 ± TCR T cells and the antibodies against both species during acute mixed malaria infection could have an impact on the immunity to malaria infection.

In vitro cytotoxicity evaluation of natural rubber latex film surface coated with PMMA nanoparticles.

In order to increase surface roughness of the sulphur-prevulcanized natural rubber (SPNR) film and, hence, decrease the direct contact between the rubber and skin, the poly(methyl methacrylate) (PMMA) latex particles were deposited onto the SPNR film grafted with polyacrylamide (SPNR-g-PAAm). The surface coverage of PMMA particles on the SPNR-g-PAAm increased with increasing latex immersion time, particle size and concentration. Prior to the in vitro cytotoxicity evaluation on L-929 fibroblasts, the SPNR and SPNR-g-PAAm coated with PMMA particles were extracted by using the culture medium. Results showed that the cytotoxicity effect could be significantly reduced by coating PMMA particles onto the rubber film. At the extract concentrations of < or =12.5% for 24h at 37 degrees C, no toxicity potential was detected. The study will be helpful for development of gloves designed for the hypersensitive person.

Reduction of cytotoxicity of natural rubber latex film by coating with PMMA-chitosan nanoparticles.

Poly(methyl methacrylate) (PMMA) latex stabilized by chitosan (CS) oligomer was synthesized via the miniemulsion polymerization. By using 1% CS solution (in 0.1M acetic acid), the spherical PMMA-CS particles with an average size of 380 nm were obtained. The positive zeta potentials at pH 2-7 confirmed the presence of CS as the outermost layer of the latex particles. Therefore, these particles directly interacted with the indigenous non-rubbers at the surface of sulphur prevulcanized natural rubber (SPNR) film. The deposition of PMMA-CS particles caused an increase in surface roughness of the coated SPNR film as a function of latex concentration and immersion time. The simple coating of the rubber substrate with PMMA-CS particles effectively reduced the in vitro cytotoxicity on L-929 cells. This study would be, therefore, helpful for development of latex gloves designed for hypersensitive users.

Immunity to Malaria in Plasmodium vivax Infection: A Study in Central China

Background P. vivax infection is characterised by relapsing fever, indicating reinfection by previously hidden parasites in the host. Relapsed infection can lead to the activation of the memory T cell pool, which may lead to protective immunity. This study aims to characterise immune responses in acute P. vivax-infected patients living in an area of central China characterised by only P. vivax infection. Methodology/Principal Findings We conducted a cross-sectional immune-phenotypic analysis of adults using the following inclusion criteria: acute P. vivax infection (N = 37), a history of P. vivax infection (N = 17), and no known history of P. vivax infection (N = 21). We also conducted a 2-week longitudinal analysis following acute P. vivax infection, in which PBMC proliferation was measured in response to P. vivax and P. falciparum blood stage lysates. Using flow cytometry, we showed elevated memory T cells in the blood during acute P. vivax infection. The levels of γδ T cells were two-fold higher than those measured in naive controls. This result suggested that in the two populations, memory and γδ T cells promptly responded to P. vivax parasites. Interestingly, P. falciparum antigens stimulated T cells obtained from P. vivax-infected patients during a day 14-convalescence, whereas lymphocytes from the naïve control group responded to a lower degree of convalescence. Conclusions/Significance Cell-mediated immunity during the convalescent period of the P. vivax-infected hosts was comprised of T cells that were specifically able to recognise P. falciparum antigens. Although the magnitude of the response was only half that measured after stimulation with P. vivax antigens, the matter of cross-antigenic stimulation is of great interest.

Detection of Campylobacter DNA using magnetic nanoparticles coupled with PCR and a colorimetric end-point system

Campylobacter is an important food-borne pathogen causing acute gastroenteritis worldwide. Magnetic nanoparticle-based PCR coupled with streptavidin-horseradish peroxidase and a substrate was used for colorimetric detection. Forward primers conjugated to magnetic nanoparticles facilitated separation and concentration of Campylobacter DNA in a sample matrix. After PCR, a green color developed and was observed using the unaided eye, or detected using a spectrophotometer. High specificity and sensitivity of the 100 fg DNA/PCR reaction were achieved in pure culture experiments. The technique was applied for detection of Campylobacter on naturally contaminated chicken skin. All positive results were in agreement with results achieved using a conventional culture method. The magnetic nanoparticle-PCR-enzyme linked gene assay was practical and useful for detection of Campylobacter in complex matrices with PCR-interfering substances.

Fluorescent chitosan functionalized magnetic polymeric nanoparticles: Cytotoxicity and in vitro evaluation of cellular uptake

Nanoparticles possessing magnetic and fluorescent properties were fabricated by the covalent attachment of fluorescein isothiocyanate onto magnetic polymeric nanoparticles functionalized by chitosan. The synthesized magnetic polymeric nanoparticles-chitosan/fluorescein isothiocyanate were successfully used for labeling the living organ and blood-related cancer cells, i.e., HeLa, Hep G2, and K562 cells. The cytotoxicity test of nanoparticles at various incubation times indicated the high cell viability (>90%) without morphological change. The confocal microscopy revealed that they could pass through cell membrane within 2 h for K562 cells and 3 h for HeLa and Hep G2 cells and then confine inside cytoplasm of all types of tested cells for at least 24 h. Therefore, the synthesized magnetic polymeric nanoparticles-chitosan/fluorescein isothiocyanate would potentially be used as cell tracking in theranostic applications.

Composite Nanoparticles on the Natural Rubber Latex Glove for Reduction of Surface Friction and Cytotoxicity

Poly(methyl methacrylate) (PMMA) particles were deposited via the Layer-by-Layer technique onto sulphur prevulcanized natural rubber latex film grafted with polyacrylamide (SPNR-g-PAAm). Besides an increase in surface hardness and roughness, hence, decrease of the surface friction of SPNR glove, a direct contact between skin and rubber film was reduced. Consequently, it was expected that the allergic problem to certain sensitive individuals and cytotoxic potential caused by the leachable non-rubbers (proteins) and lubricant powder sprinkled onto SPNR glove would be lowered. The SPNR and SPNR-g-PAAm coated with PMMA particles were extracted by using the culture medium and subjected to the in vitro cytotoxicity evaluation on L-929 fibroblasts. Results showed that the cytotoxicity was effectively reduced by coating PMMA particles onto the grafted rubber film. In order to improve both the binding ability with SPNR and antimicrobial activity, the PMMA-chitosan core-shell particles were prepared for further depositing onto the non-grafted SPNR film. Moreover, the nanocapsules containing an aqueous core of disinfectant agent (chlorhexidine digluconate) and poly(methyl acrylate) or sulphur prevulcanized skim rubber shell were prepared for being embedded in SPNR glove.

Magnetic Nanoparticles PCR Enzyme-Linked Gene Assay for Quantitative Detection of BCR/ABL Fusion Gene in Chronic Myelogenous Leukemia

Magnetic nanoparticles (MNPs) have been widely used in medical diagnostic research. In this work, two technologies, MNPs and polymerase chain reaction (PCR), were combined to increase detection sensitivity and specificity. A novel technique based on the MNPs‐PCR enzyme‐linked gene assay (MELGA) was developed for detection of the BCR/ABL abnormal gene in chronic myelogenous leukemia (CML) patients.