Non-Thermal Plasma Jet-Treated Medium Induces Selective Cytotoxicity against Mycobacterium tuberculosis-Infected Macrophages.

Plasma-treated media (PTM) serve as an adjuvant therapy to postoperatively remove residual cancerous lesions. We speculated that PTM could selectively kill cells infected with Mycobacterium tuberculosis (Mtb) and remove postoperative residual tuberculous lesions. We therefore investigated the effects of a medium exposed to a non-thermal plasma jet on the suppression of intracellular Mtb replication, cell death, signaling, and selectivity. We propose that PTM elevates the levels of the detoxifying enzymes, glutathione peroxidase, catalase, and ataxia-telangiectasia mutated serine/threonine kinase and increases intracellular reactive oxygen species production in Mtb-infected cells. The bacterial load was significantly decreased in spleen and lung tissues and single-cell suspensions from mice intraperitoneally injected with PTM compared with saline and untreated medium. Therefore, PTM has the potential as a novel treatment that can eliminate residual Mtb-infected cells after infected tissues are surgically resected.

Mycobacterium tuberculosis Rv2145c Promotes Intracellular Survival by STAT3 and IL-10 Receptor Signaling.

Although Mycobacterium tuberculosis (Mtb) is an intracellular pathogen in phagocytic cells, the factors and mechanisms by which they invade and persist in host cells are still not well understood. Characterization of the bacterial proteins modulating macrophage function is essential for understanding tuberculosis pathogenesis and bacterial virulence. Here we investigated the pathogenic role of the Rv2145c protein in stimulating IL-10 production. We first found that recombinant Rv2145c stimulated bone marrow-derived macrophages (BMDMs) to secrete IL-10, IL-6 and TNF-α but not IL-12p70 and to increase the expression of surface molecules through the MAPK, NF-κB, and TLR4 pathways and enhanced STAT3 activation and the expression of IL-10 receptor in Mtb-infected BMDMs. Rv2145c significantly enhanced intracellular Mtb growth in BMDMs compared with that in untreated cells, which was abrogated by STAT3 inhibition and IL-10 receptor (IL-10R) blockade. Expression of Rv2145c in Mycobacterium smegmatis (M. smegmatis) led to STAT3-dependent IL-10 production and enhancement of intracellular growth in BMDMs. Furthermore, the clearance of Rv2145c-expressing M. smegmatis in the lungs and spleens of mice was delayed, and these effects were abrogated by administration of anti-IL-10R antibodies. Finally, all mice infected with Rv2145c-expressing M. smegmatis died, but those infected with the vector control strain did not. Our data suggest that Rv2145c plays a role in creating a favorable environment for bacterial survival by modulating host signals.

Effects of povidone-iodine composite on the elimination of bacterial biofilm.

BACKGROUND: Povidone-iodine (PVP-I) is well known as an antiseptic and exhibits extensive activity against various pathogens. However, due to its uniquely unpleasant nature, it cannot be used locally to deactivate various sinonasal pathogens. Therefore, we developed a PVP-I composite that blocks the unpleasant odor of PVP-I for use as a local antiseptic in the sinonasal cavity and evaluated its effect on bacterial biofilm's formation and elimination in in vivo and in vitro models. METHODS: MTT, lactate dehydrogenase, and live/dead staining assay were performed to examine the cellular toxicity of PVP-I composites on the primary human nasal epithelial and RPMI 2650 cells. Crystal violet assay was performed to quantify bacterial biofilm after treating with various agents, including PVP-I and antibiotics. Hematoxylin-and-eosin staining, live/dead staining assay, and scanning electron microscopy were conducted to evaluate the effect of PVP-I on biofilm formation in a mice biofilm model. RESULTS: It was observed that the PVP-I composite did not have any significant toxic effect on the nasal epithelial cells. Furthermore, the PVP-I composite effectively inhibited the formation of bacterial biomass within a dose-dependent manner after 48 hours of incubation with Pseudomonas aeruginosa and Staphylococcus aureus. In mice, it effectively eliminated biofilm from the mucosa of the nasal cavity and maxillary sinus at the tested concentrations. CONCLUSION: The results of this study indicate that the PVP-I composite is a promising compound that could be used locally to prevent the formation of biofilms and to eliminate them from the sinonasal cavity.

Novel Cytoplasmic Bacteriocin Compounds Derived from Staphylococcus epidermidis Selectively Kill Staphylococcus aureus, Including Methicillin-Resistant Staphylococcus aureus (MRSA).

Staphylococcus aureus (S. aureus) is one of the well-known agents causing atopic dermatitis (AD) in susceptible individuals, and Staphylococcus epidermidis (S. epidermidis) produces class I thermostable bacteriocins that can selectively kill S. aureus, suggesting protective roles against AD. There is a large need for developing precise therapies only to target S. aureus and not to harm the beneficial microbiome. On the agar well diffusion assay, live planktonic S. epidermidis showed clear zones of inhibition of S. aureus growth, but heat-killed cells and cell-free supernatants did not show this. These results would lead us to hypothesize that cytoplasmic bacteriocin from S. epidermidis will be a promising agent to inhibit S. aureus growth. Therefore, we have extracted a novel thermolabile cytoplasmic bacteriocin from S. epidermidis using trichloroactic acid (TCA)/acetone precipitation method after cell lysis with a SDS-containing buffer. These bacteriocin selectively exhibited antimicrobial activity against S. aureus and methicillin-resistance Staphylococcus aureus (MRSA), presenting no active actions against S. epidermidis, E. coli, and Salmonella Typhimurium. The extracted cytoplasmic bacteriocin compounds revealed several diffuse bands of approximately 40-70 kDa by SDS-PAGE. These findings suggest that these cytoplasmic bacteriocin compounds would be a great potential means for S. aureus growth inhibition and topical AD treatment.

Characterization of an Anti-gout Xanthine Oxidase Inhibitor from Pleurotus ostreatus.

We selected Pleurotus ostreatus from among several edible mushrooms because it has high anti-gout xanthine oxidase (XOD) inhibitory activity. The maximal amount of XOD inhibitor was extracted when the Pleurotus ostreatus fruiting body was treated with distilled water at 40℃ for 48 hr. The XOD inhibitor thus obtained was purified by Sephadex G-50 gel permeation chromatography, ultrafiltration, C18 solid phase extraction chromatography and reverse-phase high-performance liquid chromatography with 3% of solid yield, and its XOD inhibitory activity was 0.9 mg/mL of IC50. The purified XOD inhibitor was a tripeptide with the amino acid sequence phenylalanine-cysteine-histidine and a molecular weight of 441.3 Da. The XOD inhibitor-containing ultrafiltrates from Pleurotus ostreatus demonstrated dose-dependent anti-gout effects in a Sprague-Dawley rat model of potassium oxonate-induced gout, as shown by decreased serum urated levels at doses of 500 and 1,000 mg/kg, although the effect was not as great as that achieved with the commercial anti-gout agent, allopurinol when administered at a dose of 50 mg/kg.

Growth characteristics and physiological functionality of yeasts in pear marc extracts.

Kluyveromyces fragilis KCTC 7260 and Saccharomyces cerevisiae KCTC 7904, which both grew well in pear marc extract, were selected and their growth profiles and physiological functionalities were determined. Both of the selected yeasts established maximal growth by 20 hr of cultivation at 30℃ in pear marc extract. The cell-free extracts showed high antihypertensive angiotensin I-converting enzyme inhibitory activity of 68.9% and 52.1%, respectively. The extracts also displayed 9.2 U/mL and 12.0 U/mL of protease activity, respectively.