Tissue-specific down-regulation of RIPK 2 in Mycobacterium leprae-infected nu/nu mice.

RIPK 2 is adapter molecule in the signal pathway involved in Toll-like receptors. However, there has been no reported association between receptor-interacting serine/threonine kinase 2 (RIPK 2) expression and the infectious diseases involving mycobacterial infection. This study found that its expression was down-regulated in the footpads and skin but was up-regulated in the liver of Mycobacterium leprae-infected nu/nu mice compared with those of the M. leprae non-infected nu/nu mice. It was observed that the interlukin-12p40 and interferon-gamma genes involved in the susceptibility of M. leprae were down-regulated in the skin but were up-regulated in the liver. Overall, this suggests that regulation of RIPK 2 expression is tissue-specifically associated with M. leprae infection

Comparison of Two Mice Strains, A/J and C57BL/6, in Caspase-1 Activity and IL-1β Secretion of Macrophage to Mycobacterium leprae Infection

A/J mice were found to have amino acid differences in Naip5, one of the NOD-like receptors (NLRs) involved in the cytosolic recognition of pathogen-associated molecular patterns and one of the adaptor proteins for caspase-1 activation. This defect was associated with a susceptibility to Legionella infection, suggesting an important role for Naip5 in the immune response also to other intracellular pathogens, such as Mycobacterium leprae. In this study, the immune responses of macrophages from A/J mice against M. leprae were compared to those of macrophages from C57BL/6 mice. Infection with M. leprae induced high levels of TNF-α production and NF-κB activation in A/J and C57BL/6 macrophages. Caspase-1 activation and IL-1β secretion were also induced in both macrophages. However, macrophages from A/J mice exhibited reduced caspase-1 activation and IL-1β secretion compared to C57BL/6 macrophages. These results suggest that NLR family proteins may have a role in the innate immune response to M. leprae

Circulating endothelial progenitor cells as a new marker of endothelial dysfunction or repair in acute stroke

BACKGROUND AND PURPOSE: Understanding on distinct subsets of endothelial progenitor cells may provide insights of endothelial dysfunction or repair in the acute ischemic event. Recent in vitro data have reported the colony-forming unit (CFU) and outgrowth cell population as a subset of endothelial progenitor cells. In this study, we undertook to validate the significance of CFU number and outgrowth cell yield in acute stroke. METHODS: Mononuclear cells were isolated from the peripheral blood of 75 patients with acute stroke, 45 patients with chronic stroke, and 40 age-matched healthy volunteers. CFU numbers were counted after culturing them for 7 days, and outgrowth cell appearance was measured during the 2 months of culture. Endothelial progenitor cell function was also evaluated by matrigel plate assays. Independent parameters predicting CFU number and outgrowth cell yield were assessed using logistic regression analysis. RESULTS: The CFU numbers and tube formation abilities in matrigel assays were significantly reduced in patients with acute stroke compared with patients with chronic stroke or healthy control subjects. Moreover, patients with large artery atherosclerosis had much lower CFU numbers and functional activities than ones with cardioembolism. Outgrowth cells were isolated from 10% of healthy control subjects and 22% of patients with chronic stroke during the cultures, but from 71% of patients with stroke. Multivariate analysis identified glycosylated hemoglobin and National Institutes of Health Stroke Scale on admission as significant independent predictors of a low CFU number and a high isolation frequency of outgrowth cells, respectively. CONCLUSIONS: CFU number may thus represent an accumulated endothelial progenitor cell dysfunctional status, whereas outgrowth cell appearance may reflect the resilience of the systemic circulation to acute ischemic stress

Influence of B1 Inhomogeneity on Pharmacokinetic Modeling of Dynamic Contrast-Enhanced MRI: A Simulation Study

Objective: To simulate the B1-inhomogeneity-induced variation of pharmacokinetic parameters on DCE-MRI. Materials and Methods: B1-inhomogeneity-induced flip angle (FA) variation was estimated in a phantom study. Monte Carlo simulation was performed to assess the FA-deviation-induced measurement error of the pre-contrast R1, contrast-enhancement ratio, Gd concentration, and two-compartment pharmacokinetic parameters (Ktrans, ve and vp). Results: B1-inhomogeneity resulted in -23% ~ 5% fluctuations (95% confidence interval (CI) of % error) of FA. The 95% CIs of FA-dependent % errors in the gray matter and blood were as follows: -16.7% - 61.8% and -16.7% - 61.8% for the pre-contrast R1, -1.0% - 0.3% and -5.2% - 1.3% for the contrast-enhancement ratio, and -14.2% - 58.1% and -14.1% - 57.8% for the Gd concentration, respectively. These resulted in -43.1% - 48.4% error for Ktrans, -32.3% - 48.6% error for the ve, and -43.2% - 48.6% error for vp. The pre-contrast R1 was more vulnerable to FA error than the contrast-enhancement ratio, and was therefore a significant cause of the Gd-concentration error. For example, a -10% FA error led to a 23.6% deviation in the pre-contrast R1, -0.4% in the contrast-enhancement ratio, and 23.6% in the Gd concentration. In a simulated condition with a 3% FA error in a target lesion and a -10% FA error in a feeding vessel, the % errors of the pharmacokinetic parameters were -23.7% for Ktrans, -23.7% for ve, and -23.7% for vp. Conclusion: Even a small degree of B1-inhomogeneity can cause a significant error in the measurement of pharmacokinetic parameters on DCE-MRI, while the vulnerability of the pre-contrast R1 calculations to FA deviations is a significant cause of the miscalculation.ope

M. leprae interacts with the human epidermal keratinocytes, neonatal (HEKn) via the binding of laminin-5 with α-dystroglycan, integrin-β1, or -β4.

Although Mycobacterium leprae (M.leprae) is usually found in macrophages and nerves of the dermis of patients with multibacillary leprosy, it is also present in all layers of the epidermis, basal, suprabasal, prickle cells, and keratin layers. However, the mechanism by which M.leprae invades the dermis remains unknown, whereas the underlying mechanism by which M.leprae invades peripheral nerves, especially Schwann cells, is well defined. M. leprae binds to the α-dystroglycan (DG) of Schwann cells via the interaction of α-DG and laminin (LN) -α2 in the basal lamina, thus permitting it to become attached to and invade peripheral nerves. In the current study, we investigated the issue of how M.leprae is phagocytosed by human epidermal keratinocytes, neonatal (HEKn). LN-5 is the predominant form of laminin in the epidermis and allows the epidermis to be stably attached to the dermis via its interaction with α/β-DG as well as integrins that are produced by keratinocytes. We therefore focused on the role of LN-5 when M. leprae is internalized by HEKn cells. Our results show that M.leprae preferentially binds to LN-5-coated slides and this binding to LN-5 enhances its binding to HEKn cells. The findings also show that pre-treatment with an antibody against α-DG, integrin-β1, or -β4 inhibited the binding of LN-5-coated M.leprae to HEKn cells. These results suggest that M. leprae binds to keratinocytes by taking advantage of the interaction of LN-5 in the basal lamina of the epidermis and a surface receptor of keratinocytes, such as α-DG, integrin-β1, or -β4