Optimal Combination of VNTR Typing for Discrimination of Isolated Mycobacterium tuberculosis in Korea / 결핵및호흡기질환

BACKGROUND: Variable-number tandem repeat (VNTR) typing is a promising method to discriminate the Mycobacterium tuberculosis isolates in molecular epidemiology. The purpose of this study is to determine the optimal VNTR combinations for discriminating isolated M. tuberculosis strains in Korea. METHODS: A total of 317 clinical isolates collected throughout Korea were genotyped by using the IS6110 restriction fragment length polymorphism (RFLP), and then analysed for the number of VNTR copies from 32 VNTR loci. RESULTS: The results of discriminatory power according to diverse combinations were as follows: 25 clusters in 83 strains were yielded from the internationally standardized 15 VNTR loci (Hunter-Gaston discriminatory index [HGDI], 0.9958), 25 clusters in 65 strains by using IS6110 RFLP (HGDI, 0.9977), 14 clusters in 32 strains in 12 hyper-variable VNTR loci (HGDI, 0.9995), 6 clusters in 13 strains in 32 VNTR loci (HDGI, 0.9998), and 7 clusters in 14 strains of both the 12 hyper-variable VNTR and IS6110 RFLP (HDGI, 0.9999). CONCLUSION: The combination of 12 hyper-variable VNTR typing can be an effective tool for genotyping Korean M. tuberculosis isolates where the Beijing strains are predominant.

Intracellular Signaling Pathways that Regulate Macrophage Chemokine Expression in Response to Mycobacterium abscessus

Mycobacterium abscessus (Mabc) is an emerging human pathogen. Less is known about the host immune response to Mabc than to M. tuberculosis. Here, we examined the intracellular signaling pathways that govern the expression of chemokines including (C-C motif) ligand 2 (CCL2) and (C-X-C motif) ligand 2 (CXCL2) in macrophages after infection with Mabc. Specifically, Mabc triggered the generation of reactive oxygen species (ROS) and the production of CCL2 and CXCL2 in murine bone marrow-derived macrophages (BMDMs). Mabc-induced CCL2, but not CXCL2, was dependent on the generation of ROS. Toll-like receptor (TLR) 2, MyD88, but not TRIF, was required for Mabc-induced CCL2 and CXCL2 expression. Additionally, Mabc infection significantly induced nuclear factor (NF)-kappaB nuclear translocation and luciferase activity. The activation of NF-kappaB was required for Mabc-induced CCL2, but not CXCL2 expression. Moreover, Mabc-induced ROS generation was required for NF-kappaB activation. Treatment of BMDMs with Mabc rapidly induced the activation of mitogen-activated protein kinase (MAPKs) pathways. Interestingly, CCL2 expression was dependent on the activation of JNK and ERK1/2 pathways, whereas it was negatively regulated by the p38 MAPK pathway. In contrast, Mabc-dependent CXCL2 expression was not regulated by MAPK pathways. These data suggest that intracellular ROS generation is required for innate and inflammatory responses during Mabc infection of macrophages.