Mesenchymal Stem Cell-Derived Exosomes Attenuate TLR7-Mediated Mast Cell Activation

BACKGROUND@#Mast cells are immune sentinels in the skin that respond to a wide range of pathological and environmental stimuli; they owe their function to the expression of Toll-like receptors (TLRs). We previously found that tonsilderived mesenchymal stem cells (T-MSCs) were able to effectively attenuate TLR7-mediated skin inflammation in mice, which was accompanied by an increase in mast cell number. The present study investigated whether T-MSC extracellular vesicles, such as exosomes, are able to regulate mast cell activation in response to TLR7 stimulation. @*METHODS@#The HMC-1 human mast cell line was treated with a TLR7 agonist in the presence or absence of T-MSC exosomes, and the levels of expressed inflammatory cytokines were assessed. Additionally, mice were repeatedly injected with a TLR7 agonist with or without interval treatments with T-MSC exosomes and assessed dermal distribution of mast cells and related immune cells. @*RESULTS@#We showed that T-MSC exosomes containing microRNAs that target inflammatory cytokines significantly reduced the expression of inflammatory cytokines in TLR7 agonist-treated HMC-1 cells. In addition, T-MSC exosomes inhibited the increase in the number of both dermal mast cells and CD14-positive cells in TLR7 agonist-treated mice. @*CONCLUSION@#Our data suggest that T-MSC exosomes have regulatory effects on mast cell activation under inflammatory conditions, including TLR7 stimulation.

Escherichia coli pap Genes as well as Adenovirus Type 11 and Type 21, and BK Virus were Involved with Severe Urinary Tract Infection in Infants

In infants, urinary tract infections (UTIs) are quite common and primarily caused by bacterial pathogens. However, little research has been conducted regarding the relationship between uropathogenic bacteria, virulent genes, and uropathogenic viruses that might induce UTIs in infants. In this study, we evaluated infants with UTIs to determine the influence of bacterial virulent genes and type of viral infections on clinical aspects. First, we detected 44 cases of bacterial UTI from 600 suspected cases in infants and children. We detected E. coli urovirulence genes (kps, usp, pap, ireA, and cnf), two enteropathogenic E. coli genes (bfpA, and eae) and four S. aureus and S. epidermidis genes (mecA, pvl, bbp, and icaA) in urine samples from infant UTI cases. We also simultaneously detected hematuria-related adenovirus type 11, 21, and BK virus (BKV) in urine samples by PCR. As a result, E. coli was the most prevalent bacteria and in Dimercaptosuccinic acid (DMSA)-positive UTI cases, the uropathogenic E. coli virulence factor pap was significantly high. We found that BKV detection was significantly higher in DMSA-positive UTI infants (89%) compared with 50% of non-UTI (no bacteria detected) cases. These results are indicative of combined multiple bacterial and viral infections and show severe infant pyelonephritis.

Oral Tolerance Increased the Proportion of CD8+ T Cells in Mouse Intestinal Lamina Propria

BACKGROUND: Oral tolerance is defined by the inhibition of immune responsiveness to a protein previously exposed via the oral route. Protein antigens exposed via the oral route can be absorbed through the mucosal surfaces of the gastrointestinal tract and can make physical contact with immune cells residing in the intestinal lamina propria (LP). However, the mechanisms of oral tolerance and immune regulation in the intestines currently remain to be clearly elucidated. METHODS: In order to determine the effect of oral protein antigen intake (ovalbumin, OVA) on the intestinal LP, we assessed the expression profile of the T cell receptor and the co-receptors on the cells from the intestines of the tolerant and immune mouse groups. RESULTS: We determined that the proportion of OVA-specific B cells and gamma delta T cells had decreased, but the CD8alpha beta and CD8alpha alpha T cells were increased in the LP from the tolerant group. The proportion of CD8+ T cells in the spleen did not evidence any significant differences between treatment groups. CONCLUSION: These results indicate that CD8+ T cells in the intestinal LP may perform a regulatory role following antigen challenge via the oral route.

Detection of Virulence Genes of Staphyloccus aureus and Staphylococcus epidermidis Isolated from Suprapubic Urine from Infants with Fever

While methicillin-resistant Staphylococcus aureus (MRSA) isolated from urinary tract infection (UTI) has recently increased in elderly adult urology patients, it has been only rarely reported in infants. Therefore, in this study to understand whether MRSA may be involved in UTI of infants who run fever without other apparent causes, we identified and counted S. aureus and S. epidermidis in suprapubic urine from 750 febrile infants via microbiological methods, and confirmed the counts via multiplex PCR. And we also detected four virulence genes, mecA, PVL, bbp and icaA genes for S. aureus and S. epidermidis via multiplex PCR in the same specimens. S. aureus (28 cases) counts were as follows: >10(4) CFU/ml (3/28), 10(2)~10(3) CFU/ml (1/28) and 10(4) CFU/ml (2/26), 10(2)~10(3) CFU/ml (4/26) and 10(2)~10(3) CFU/ml (20/26). S. aureus virulence genes were detected in 26 cases as mecA (16/26, 59.3%), PVL (17/26, 63.0%), bbp (7/26, 26.9%) and icaA (20/26, 76.9%). S. epidermidis virulence genes were detected in 22 cases as mecA (17/22, 81.0%), PVL (15/22, 71.4%), bbp (3/22, 13.6%) and icaA (13/22, 50.1%). Therefore, mecA, PVL and icaA genes of MRSA and MRSE were detected with high positivity in urines from infants with fever. The results demonstrate that community-acquired MRSA or MRSE may be responsible for UTI incidence in febrile infants.

Effect on Cell Cycle Progression by N-Myc Knockdown in SK-N-BE(2) Neuroblastoma Cell Line and Cytotoxicity with STI-571 Compound / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Neuroblastoma is a common tumor in childhood, and generally exhibits heterogeneity and a malignant progression. MYCN expression and amplification profiles frequently correlate with therapeutic prognosis. Although it has been reported that MYCN silencing causes differentiation and apoptosis in human neuroblastoma cells, MYCN expression influences the cytotoxic potential of chemotherapeutic drugs via the deregulation of the cell cycle. STI-571 may constitute a promising therapeutic agent against neuroblastoma, particularly in cases in which c-Kit is expressed preferentially in MYCN-amplified neuroblastoma. MATERIALS AND METHODS: To determine whether STI-571 exerts a synergistic effect on cytotoxicity with MYCN expression, we assessed apoptotic cell death and cell cycle distribution after 72 h of exposure to STI-571 with or with out treatment of SK-N-BE(2) neuroblastoma cells with MYCN siRNA. RESULTS: MYCN siRNA-treated SK-N-BE(2) cells did not affect apoptosis and cells were arrested in G0/G1 phase after STI-571 treatment. CONCLUSIONS: siRNA therapy targeted to MYCN may not be effective when administered in combination with STI-571 treatment in cases of neuroblastoma. Therefore, chemotherapeutic drugs that target S or G2-M phase may prove ineffective when applied to cells arrested in the G0/1 phase as the result of MYCN knockdown and STI-571 treatment.

Plasmodium falciparum Cultivation Using the Petri Dish: Revisiting the Effect of the 'Age' of Erythrocytes and the Interval of Medium Change

Differences in the characteristics of the culture conditions can influence the multiplication rate of Plasmodium falciparum. The Petri dish method is one of the most popular methods of cultivating this parasite. In many previous studies, ideal culture conditions of the Petri dish method were achieved by using erythrocytes collected from blood that had been stored for at least 2 weeks, with daily changes of the medium. In the present study, we studied the multiplication rate of P. falciparum in cultures containing erythrocytes of various ages together with changing the medium at various intervals of time. Our results strongly suggest that the rate of in vitro multiplication of P. falciparum was higher in freshly collected erythrocytes than in aged erythrocytes regardless of the anticoagulant and that when the parasitemia is lower than 8% with a hematocrit of 5%, the medium change interval can be as long as 48 hr without a great reduction in the rate of multiplication.

Evaluation of Anti-Malarial Effects of Mass Chemoprophylaxis in the Republic of Korea Army

Vivax malaria was endemic on the Korean peninsula for many centuries until the late 1970's when the Republic of Korea (ROK) was declared "malaria free". Since its re-emergence in 1993, the number of malaria cases in the military increased exponentially through 2000 near the demilitarized zone. Chemoprophylaxis with chloroquine and primaquine has been used in the ROK Army since 1997 in an attempt to reduce the number of the malaria cases throughout the ROK. Data show that chemoprophylaxis contributed, in part, to the decrease in the number of malaria cases among military personnel. However, mass chemoprophylaxis on a large scale in the ROK Army is unprecedented and extensive supervision and monitoring is warranted to determine its effectiveness and to monitor the appearance of chloroquine tolerant/resistant strains of Plasmodium vivax.