SUMMARYToll-like receptor 2 (TLR2) is a key mediator of the immune response to mycobacterial infections, and mutations in TLR2 have been shown to confer susceptibility to infection with mycobacteria. This study investigated the profiles of cytokines, such as interferon (IFN)-c, interleukin (IL)-10, IL-12 and tumour necrosis factor (TNF)-a in response to Mycobacterium leprae in peripheral blood mononuclear cells (PBMC) with the TLR2 mutation Arg677Trp, a recently reported polymorphism that is associated with lepromatous leprosy. In leprosy patients with the TLR2 mutation, production of IL-2, IL-12, IFN-c, and TNF-a by M. leprae-stimulated PBMC were significantly decreased compared with that in groups with wild-type TLR2. However, the cells from patients with the TLR2 mutation showed significantly increased production of IL-10. There was no significant difference in IL-4 production between the mutant and wild-type during stimulation. Thus, these results suggest that the TLR2 signal pathway plays a critical role in the alteration of cytokine profiles in PBMC from leprosy patients and the TLR2 mutation Arg677Trp provides a mechanism for the poor cellular immune response associated with lepromatous leprosy.

Bcl-2 interacting cell death suppressor (Bis), also known as Bag3 or CAIR-1, is involved in antistress and antiapoptotic pathways. In addition to Bcl-2, Bis binds to several proteins, suggesting it has diverse functions in normal and pathological conditions. To better define the physiological function of Bis in vivo, we developed bis-deficient mice with a cre-loxP system. Targeted disruption of exon 4 of the bis gene was demonstrated by Southern blotting and PCR, and Western blotting showed that no intact or truncated Bis protein was synthesized in bis(-/-) mice. While heterozygotes were fertile and appeared normal, Bis-deficient mice showed growth retardation and died by 3 wk after birth. The relative weight of the thymus and spleen was reduced and the total numbers of white blood cells, splenocytes, and thymocytes were significantly reduced compared with wild-type littermates. Serum profiles indicated significant hypoglycemia as well as decrease in triglyceride and cholesterol levels. Expression profiles of metabolic genes indicated that gluconeogenesis and beta-oxidation are activated in the liver of bis(-/-) mice. This activation, as well as a decrease in peripheral fat and an induction of fatty liver, appears to be an adaptive response to hypoglycemia. Our study reveals that the absence of Bis has considerable influences on postnatal growth and survival, possibly due to a nutritional impairment.

Mesenchymal stem cells (MSCs) are known to be effective in wound healing, but not much has been reported on quantitative correlations between MSCs injected into the wound site and MSCs that actually participate in wound healing. This study traced MSCs participating in wound healing by using small intestinal submucosa (SIS) as a cell carrier, identified their moving path and calculated the number of MSCs involved in wound healing. First, MSCs were isolated from the nude mouse and 1 Â 10 6 cells were seeded onto the centre of the SIS. MSC-seeded SIS complexes were injected onto full-thickness skin wounds made on the dorsum of nude mice. Tracing of MSC-seeded SIS complex transplanted to the wound site revealed that 27.6% of the MSCs were migrated to the wound site at the first attempt. Second, repeated injection of additional MSCs did not increase the number of MSCs participating in wound healing beyond a certain constant maximum amount. The number of MSCs present in the wound site remains constant in the range 2-3 Â 10 5 from day 1 to day 10. The expression of skin regenerationrelated growth factors was confirmed by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). MSCs participating in wound healing were found not only to suppress inflammation of the wound but also to increase the skin regeneration-related growth factors that enable the recovery of the skin. An optimal number of about 3 Â 10 5 MSCs injected into the site was found to adapt themselves to the skin wound-healing process effectively.

Rifampicin is a macrocyclic antibiotic which is used extensively for treatment against Mycobacterium tuberculosis and other mycobacterial infections. Recently, a number of studies have focused on the immune-regulatory effects of rifampicin. Therefore, we hypothesized that rifampicin may influence the TLR2 expression in LPS-activated RAW 264.7 cells. In this study, we determined that rifampicin suppresses LPS-induced TLR2 mRNA expression. The down-regulation of TLR2 expression coincided with decreased production of TNF-α. Since NF-κB is a major transcription factor that regulates genes for TLR2 and TNF-α, we examined the effect of rifampicin on the LPS-induced NF-κB activation. Rifampicin inhibited NF-κB DNA-binding activity in LPS-activated RAW 264.7 cells, while it did not affect IKKα/β activity. However, rifampicin slightly inhibited the nuclear translocation of NF-κB p65. In addition, rifampicin increased physical interaction between pregnane X receptor, a receptor for rifampicin, and NF-κB p65, suggesting pregnane X receptor interferes with NF-κB binding to DNA. Taken together, our results demonstrate that rifampicin inhibits LPS-induced TLR2 expression, at least in part, via the suppression of NF-κB DNA-binding activity in RAW 264.7 cells. Thus, the present results suggest that the rifampicin-mediated inhibition of TLR2 via the suppression of NF-κB DNAbinding activity may be a novel mechanism of the immune-suppressive effects of rifampicin.

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Bis (Bag3) is known to be involved in cell survival, migration, the regulating of chaperones, and protein quality control. We reported recently on the production of bis gene-deleted mice, which show early lethality within 3 wk after birth with a phenotype showing severe malnutrition and shrinkage of the thymus. In this report, we provide evidence to show that an intrinsic problem of adrenal gland is the the primary cause for the severe atrophy of the thymus in bis−/− mice. The bis−/− mice show significantly higher levels of corticosterone, but CRH and ACTH levels were considerably lower than those of wild littermates. The transcription of steroidogenic enzymes was increased in the adrenal glands of bis−/− mice, accompanied by an increase in the thickness of the zona reticularis. An analysis of thymus tissue from bis−/− mice revealed that the severe atrophy of the thymus is due to the specific loss of immature double-positive (CD4+CD8+) cortical thymocytes by apoptosis, as evidenced by immunohistochemical examination and flow cytometric analysis, which were restored by injection of an inhibitor of glucocorticoid synthesis. In vitro cultures of thymocytes with increasing doses of dexamethasone exhibited a similar degree of apoptosis between wild and bis−/− thymocytes. The corticosterone levels from fasted wild littermates were one-half those of bis−/− mice, although serum glucose levels were similar. Thus, the deletion of the bis gene resulted in the intrinsic defect in the adrenal gland, leading to a marked increase in glucocorticoid levels, probably upon starvation stress, which accounts for the massive apoptosis of the thymus.