Pam2CSK4 and Pam3CSK4 induce iNOS expression via TBK1 and MyD88 molecules in mouse macrophage cell line RAW264.7.

OBJECTIVE: The aim of this study was to investigate the involvement of TLR adaptor molecules, such as TRIF, MyD88, and TBK1 in the induction of iNOS and nitric oxide (NO) production in Pam2CSK4 and Pam3CSK4-treated mouse macrophages. METHOD: Mouse macrophage cell line (RAW264.7) was transfected with trif, myd88, and tbk1 siRNAs before stimulated with Pam2CSK4 and Pam3CSK4. The iNOS gene and protein expression were determined by RT-PCR and immunoblotting, respectively. The NO production was determined by Griess reaction assay. RESULTS: The results showed that the induction of iNOS expression and NO production by Pam2CSK4 and Pam3CSK4 were diminished in tbk1 and myd88-depleted mouse macrophages but not trif-depleted cells. CONCLUSION: These results suggested that the TBK1 and MyD88 molecules were essential for the induction of iNOS expression and NO production by both Pam2CSK4 and Pam3CSK4 via TLR2 signaling.

Burkholderia pseudomallei induces IL-23 production in primary human monocytes.

Burkholderia pseudomallei, a gram-negative intracellular bacterium, is a causative agent of melioidosis. The bacterium has been shown to induce the innate immune response, particularly pro-inflammatory cytokine production in several of both mouse and human cell types. In the present study, we investigate host immune response in B. pseudomallei-infected primary human monocytes. We discover that wild-type B. pseudomallei is able to survive and multiply inside the primary human monocytes. In contrast, B. pseudomallei LPS mutant, a less virulent strain, is susceptible to host killing during bacterial infection. Moreover, microarray result showed that wild-type B. pseudomallei but not B. pseudomallei LPS mutant is able to activate gene expression of IL-23 as demonstrated by the up-regulation of p19 and p40 subunit expression. Consistent with gene expression analysis, the secretion of IL-23 analyzed by ELISA also showed that wild-type B. pseudomallei induces a significantly higher level of IL-23 secretion than that of B. pseudomallei LPS mutant. These results implied that IL-23 may be an important cytokine for the innate immune response during B. pseudomallei infection. The regulation of IL-23 production may drive the different host innate immune responses between patients and may relate to the severity of melioidosis.

Incidence and risk factors of blastocystis infection in orphans at the Babies' Home, Nonthaburi Province, Thailand.

BACKGROUND: Blastocystis infection is one of the most common intestinal protozoan infections reported in Thai population of all age groups for which epidemiological information is important to understand patterns of transmission for developing methods ofprevention and control for each specific group. The authors aimed to study prevalence, incidence and riskfactors associated with Blastocystis infection in orphans and childcare workers. Additionally, subtypes ofBlastocystis were identified MATERIAL AND METHOD: A retrospective cohort study of Blastocystis sp. was conducted in orphans aged less than 5 years and their childcare workers at Babies' Home, Nonthaburi Province, Thailand. A base line survey was conducted in December 2009 and afollow-up survey was conducted in April 2010. A total of 336 and 331 stool samples were collected. Blastocystis infection was examined using short-term in vitro cultivation in Jones's medium supplemented with 10% fetal calf serum. To analyze subtypes ofBlastocystis sp., PCR-RFLP of the small subunit ribosomal RNA gene was performed. RESULTS: Theprevalence ofBlastocystis infection in December 2009 and April 2010 were 8.1% and 13.3%, respectively The inlcidence rate ofBlastocystis infection was 1.6/100 person-months. Subtype analysis ofBlastocystis sp. in December 2009 and in April 2010 showed that subtype 3 was the most predominant (76% and 76%), followed by subtype 1 (16% and 20%), and unidentified subtype (8% and 4%), respectively. Subtype 3 is of human origin, thus person-to-person transmission is considered a major route ofBlastocystis infection in this population. CONCLUSION: Person-to-person transmission of Blastocystis infection in orphans living in the same house had been proposed, thus the prevalence and incidence of Blastocystis infection could be used to reflect the hygienic condition in the orphanage. Infection prevention and control practice can be effectively implemented.

An Epidemiological Survey of Opisthorchis viverrini Infection in a Lightly Infected Community, Eastern Thailand.

Human liver fluke infection caused by Opisthorchis viverrini increases the risk of cholangiocarcinoma (CCA) reported along the Mekong basin including Thailand, Lao People's Democratic Republic (PDR), Cambodia, and Vietnam. The highest incidence of CCA has been reported in northeastern Thailand where liver fluke infection is prevalent. This study aimed to investigate the prevalence of O. viverrini infection in a northeastern-descendent community in rural Sa Kaeo Province, eastern Thailand, using stool examination and molecular technique. The Kato-Katz method was performed to determine eggs per gram (EPG) for infection intensity. Phosphate-buffered saline-ethyl acetate concentration was used to prepare specimens for polymerase chain reaction (PCR) and restriction fragment length polymorphism of the internal transcribed spacer 2 (ITS2) region of the ribosomal RNA. From 1,245 specimens, 105 (8.4%) samples were identified as Opisthorchis-like eggs from stool examination, and all positive specimens indicated light infection (< 1,000 EPG). From positive Opisthorchis-like egg samples, 55.2% (58/105) were identified as O. viverrini eggs from ITS2-PCR assay for which low infection intensity might result in a negative PCR result (44.8%). Using multiple logistic regression analysis, males were at 3.1 times higher risk of acquiring O. viverrini infection than females. From phylogenetic analysis, in eastern Thailand, nucleotide sequences of O. viverrini were grouped as a monoclade as those isolated from Greater Mekong, Vietnam, Myanmar, and west Siberia. The results revealed that the surveyed community is a low-grade endemic area of O. viverrini infection. Thus, data from this study can be used to improve health-promoting programs and activities to control the infection and its subsequent CCA.