Trehalose-6-Phosphate-Mediated Toxicity Determines Essentiality of OtsB2 in Mycobacterium tuberculosis In Vitro and in Mice.

Trehalose biosynthesis is considered an attractive target for the development of antimicrobials against fungal, helminthic and bacterial pathogens including Mycobacterium tuberculosis. The most common biosynthetic route involves trehalose-6-phosphate (T6P) synthase OtsA and T6P phosphatase OtsB that generate trehalose from ADP/UDP-glucose and glucose-6-phosphate. In order to assess the drug target potential of T6P phosphatase, we generated a conditional mutant of M. tuberculosis allowing the regulated gene silencing of the T6P phosphatase gene otsB2. We found that otsB2 is essential for growth of M. tuberculosis in vitro as well as for the acute infection phase in mice following aerosol infection. By contrast, otsB2 is not essential for the chronic infection phase in mice, highlighting the substantial remodelling of trehalose metabolism during infection by M. tuberculosis. Blocking OtsB2 resulted in the accumulation of its substrate T6P, which appears to be toxic, leading to the self-poisoning of cells. Accordingly, blocking T6P production in a ΔotsA mutant abrogated otsB2 essentiality. T6P accumulation elicited a global upregulation of more than 800 genes, which might result from an increase in RNA stability implied by the enhanced neutralization of toxins exhibiting ribonuclease activity. Surprisingly, overlap with the stress response caused by the accumulation of another toxic sugar phosphate molecule, maltose-1-phosphate, was minimal. A genome-wide screen for synthetic lethal interactions with otsA identified numerous genes, revealing additional potential drug targets synergistic with OtsB2 suitable for combination therapies that would minimize the emergence of resistance to OtsB2 inhibitors.

Interleukin-26 activates macrophages and facilitates killing of Mycobacterium tuberculosis.

Tuberculosis-causing Mycobacterium tuberculosis (Mtb) is transmitted via airborne droplets followed by a primary infection of macrophages and dendritic cells. During the activation of host defence mechanisms also neutrophils and T helper 1 (TH1) and TH17 cells are recruited to the site of infection. The TH17 cell-derived interleukin (IL)-17 in turn induces the cathelicidin LL37 which shows direct antimycobacterial effects. Here, we investigated the role of IL-26, a TH1- and TH17-associated cytokine that exhibits antimicrobial activity. We found that both IL-26 mRNA and protein are strongly increased in tuberculous lymph nodes. Furthermore, IL-26 is able to directly kill Mtb and decrease the infection rate in macrophages. Binding of IL-26 to lipoarabinomannan might be one important mechanism in extracellular killing of Mtb. Macrophages and dendritic cells respond to IL-26 with secretion of tumor necrosis factor (TNF)-α and chemokines such as CCL20, CXCL2 and CXCL8. In dendritic cells but not in macrophages cytokine induction by IL-26 is partly mediated via Toll like receptor (TLR) 2. Taken together, IL-26 strengthens the defense against Mtb in two ways: firstly, directly due to its antimycobacterial properties and secondly indirectly by activating innate immune mechanisms.

Neurofunctional modulation of brain regions by distinct forms of motor cognition and movement features.

Extrastriate, parietal, and frontal brain regions are differentially involved in distinct kinds of body movements and motor cognition. Using functional magnetic resonance imaging, we investigated the neural mechanisms underlying the observation and mental imagery of meaningful face and limb movements with or without objects. The supplementary motor area was differentially recruited by the mental imagery of movements while there were differential responses of the extrastriate body area (EBA) during the observation conditions. Contrary to most previous reports, the EBA responded to face movements, albeit to a lesser degree than to limb movements. The medial wall of the intraparietal sulcus and adjacent intraparietal cortex was selectively recruited by the processing of meaningful upper limb movements, irrespective of whether these were object-related or not. Besides reach and grasp movements, the intraparietal sulcus may thus be involved in limb gesture processing, that is, in an important aspect of human social communication. We conclude that subregions of a frontal-parietal network differentially interact during the cognitive processing of body movements according to the specific motor-related task at hand and the particular movement features involved.

Validation and update of a lymph node metastasis prediction model for breast cancer.

PURPOSE: This study aimed to validate and update a model for predicting the risk of axillary lymph node (ALN) metastasis for assisting clinical decision-making. METHODS: We included breast cancer patients diagnosed at six Dutch hospitals between 2011 and 2015 to validate the original model which includes six variables: clinical tumor size, tumor grade, estrogen receptor status, lymph node longest axis, cortical thickness and hilum status as detected by ultrasonography. Subsequently, we updated the original model using generalized linear model (GLM) tree analysis and by adjusting its intercept and slope. The area under the receiver operator characteristic curve (AUC) and calibration curve were used to assess the original and updated models. Clinical usefulness of the model was evaluated by false-negative rates (FNRs) at different cut-off points for the predictive probability. RESULTS: Data from 1416 patients were analyzed. The AUC for the original model was 0.774. Patients were classified into four risk groups by GLM analysis, for which four updated models were created. The AUC for the updated models was 0.812. The calibration curves showed that the updated model predictions were better in agreement with actual observations than the original model predictions. FNRs of the updated models were lower than the preset 10% at all cut-off points when the predictive probability was less than 12.0%. CONCLUSIONS: The original model showed good performance in the Dutch validation population. The updated models resulted in more accurate ALN metastasis prediction and could be useful preoperative tools in selecting low-risk patients for omission of axillary surgery.

"Intermittent claudication intermittence" as a manifestation of adventitial cystic disease communicating with the knee joint.

In this report, we describe a patient with adventitial cystic disease of the popliteal artery, in which direct communication via a duct-like structure between the cystic lesion and the knee-joint synovium resulted in recurrent episodes of intermittent claudication and complete symptom-free intervals (intermittent claudication intermittence). This unusual observation could shed more light on the debated etiology of the disease. Moreover, it emphasizes the importance of complete excision of the cyst along with the presenting anatomic connection with the knee joint.