Airway epithelium-shifted mast cell infiltration regulates asthmatic inflammation via IL-33 signaling.

Asthma is a heterogeneous syndrome that has been subdivided into physiologic phenotypes and molecular endotypes. The most specific phenotypic manifestation of asthma is indirect airway hyperresponsiveness (AHR), and a prominent molecular endotype is the presence of type 2 inflammation. The underlying basis for type 2 inflammation and its relationship to AHR are incompletely understood. We assessed the expression of type 2 cytokines in the airways of subjects with and without asthma who were extensively characterized for AHR. Using quantitative morphometry of the airway wall, we identified a shift in mast cells from the submucosa to the airway epithelium specifically associated with both type 2 inflammation and indirect AHR. Using ex vivo modeling of primary airway epithelial cells in organotypic coculture with mast cells, we show that epithelial-derived IL-33 uniquely induced type 2 cytokines in mast cells, which regulated the expression of epithelial IL33 in a feed-forward loop. This feed-forward loop was accentuated in epithelial cells derived from subjects with asthma. These results demonstrate that type 2 inflammation and indirect AHR in asthma are related to a shift in mast cell infiltration to the airway epithelium, and that mast cells cooperate with epithelial cells through IL-33 signaling to regulate type 2 inflammation.

Clinical utility of rosuvastatin and other statins for cardiovascular risk reduction among the elderly.

Age is one of the strongest predictors of cardiovascular disease (CVD) risk. Treatment with statins can significantly reduce CVD events and mortality in both primary and secondary prevention. Yet despite the high CVD risk among the elderly, there is underutilization of statins in this population (ie, the treatment-risk paradox). Few studies have investigated the use of statins in the elderly, particularly for primary prevention and, as a result, guidelines for treating the elderly are limited. This is likely due to: uncertainties of risk assessment in older individuals where the predictive value of individual risk factors is decreased; the need to balance the benefits of primary prevention with the risks of polypharmacy, health care costs, and adverse medication effects in a population with decreased life expectancy; the complexity of treating patients with many other comorbidities; and increasingly difficult social and economic concerns. As life expectancy increases and the total elderly population grows, these issues become increasingly important. JUPITER (Justification for the Use of statins in Prevention: an Intervention Trial Evaluating Rosuvastatin) is the largest primary prevention statin trial to date and enrolled a substantial number of elderly adults. Among the 5695 JUPITER participants ≥ 70 years of age, the absolute CVD risk reduction associated with rosuvastatin was actually greater than for younger participants. The implications of this JUPITER subanalysis and the broader role of statins among older adults is the subject of this review.

Radiosensitivity profiles from a panel of ovarian cancer cell lines exhibiting genetic alterations in p53 and disparate DNA-dependent protein kinase activities.

The variability of radiation responses in ovarian tumors and tumor-derived cell lines is poorly understood. Since both DNA repair capacity and p53 status can significantly alter radiation sensitivity, we evaluated these factors along with radiation sensitivity in a panel of sporadic human ovarian carcinoma cell lines. We observed a gradation of radiation sensitivity among these sixteen lines, with a five-fold difference in the LD50 between the most radiosensitive and the most radioresistant cells. The DNA-dependent protein kinase (DNA-PK) is essential for the repair of radiation induced DNA double-strand breaks in human somatic cells. Therefore, we measured gene copy number, expression levels, protein abundance, genomic copy and kinase activity for DNA-PK in all of our cell lines. While there were detectable differences in DNA-PK between the cell lines, there was no clear correlation with any of these differences and radiation sensitivity. In contrast, p53 function as determined by two independent methods, correlated well with radiation sensitivity, indicating p53 mutant ovarian cancer cells are typically radioresistant relative to p53 wild-type lines. These data suggest that the activity of regulatory molecules such as p53 may be better indicators of radiation sensitivity than DNA repair enzymes such as DNA-PK in ovarian cancer.

Architecture and flexibility of the yeast Ndc80 kinetochore complex.

Kinetochores mediate microtubule-chromosome attachment and ensure accurate segregation of sister chromatids. The highly conserved Ndc80 kinetochore complex makes direct contacts with the microtubule and is essential for spindle checkpoint signaling. It contains a long coiled-coil region with globular domains at each end involved in kinetochore localization and microtubule binding, respectively. We have directly visualized the architecture of the yeast Ndc80 complex and found a dramatic kink within the 560-A coiled-coil rod located about 160 A from the larger globular head. Comparison of our electron microscopy images to the structure of the human Ndc80 complex allowed us to position the kink proximal to the microtubule-binding end and to define the conformational range of the complex. The position of the kink coincides with a coiled-coil breaking region conserved across eukaryotes. We hypothesize that the kink in Ndc80 is essential for correct kinetochore geometry and could be part of a tension-sensing mechanism at the kinetochore.

Assembly of GMPCPP-bound tubulin into helical ribbons and tubes and effect of colchicine.

Microtubule assembly and disassembly is a complex structural process that does not proceed by simple addition and subtraction of individual subunits to and from a helical polymer, as would be the case for actin and other helical assemblies. The dynamic process of microtubule growth and shrinking involves short-lasting polymer forms that differ substantially from the microtubule itself and constitute crucial assembly and disassembly intermediates. Structural characterization thus depends on the stabilization of these brief intermediates and their preservation as polymeric assemblies. This paper gives experimental details on the polymerization of GMPCPP-tubulin into low-temperature, stable polymers that we propose to correspond to the early stages in microtubule assembly, and includes new data on the effect of colchicine on GMPCPP-tubulin polymerization. Finally, we add our thoughts on the possible biological meaning of tubulin polymerization versatility.