Lifespan Extension by Preserving Proliferative Homeostasis in Drosophila

Regenerative processes are critical to maintain tissue homeostasis in high-turnover tissues. At the same time, proliferation of stem and progenitor cells has to be carefully controlled to prevent hyper-proliferative diseases. Mechanisms that ensure this balance, thus promoting proliferative homeostasis, are expected to be critical for longevity in metazoans. The intestinal epithelium of Drosophila provides an accessible model in which to test this prediction. In aging flies, the intestinal epithelium degenerates due to over-proliferation of intestinal stem cells (ISCs) and mis-differentiation of ISC daughter cells, resulting in intestinal dysplasia. Here we show that conditions that impair tissue renewal lead to lifespan shortening, whereas genetic manipulations that improve proliferative homeostasis extend lifespan. These include reduced Insulin/IGF or Jun-N-terminal Kinase (JNK) signaling activities, as well as over-expression of stress-protective genes in somatic stem cell lineages. Interestingly, proliferative activity in aging intestinal epithelia correlates with longevity over a range of genotypes, with maximal lifespan when intestinal proliferation is reduced but not completely inhibited. Our results highlight the importance of the balance between regenerative processes and strategies to prevent hyperproliferative disorders and demonstrate that promoting proliferative homeostasis in aging metazoans is a viable strategy to extend lifespan

Cell distribution and cytokine levels in induced sputum from healthy subjects and patients with asthma after using different nebulizer techniques

Abstract Background Sputum induction is an important noninvasive method for analyzing bronchial inflammation in patients with asthma and other respiratory diseases. Most frequently, ultrasonic nebulizers are used for sputum induction, but breath-controlled nebulizers may target the small airways more efficiently. This treatment may produce a cell distribution similar to bronchoalveolar lavage (less neutrophils and more macrophages) and provide deeper insights into the underlying lung pathology. The goal of the study was to compare both types of nebulizer devices and their efficacy in inducing sputum to measure bronchial inflammation, i.e., cell composition and cytokines, in patients with mild allergic asthma and healthy controls. Methods The population of this study consisted of 20 healthy control subjects with a median age of 17 years, range: 8–25 years, and 20 patients with a median age of 12 years, range: 8–24 years, presenting with mild, controlled allergic asthma who were not administered an inhaled steroid treatment. We induced sputum in every individual using both devices on two separate days. The sputum weight, the cell composition and cytokine levels were analyzed using a cytometric bead assay (CBA) and by real-time quantitative PCR (qRT-PCR). Results We did not observe significant differences in the weight, cell distribution or cytokine levels in the sputum samples induced by both devices. In addition, the Bland-Altman correlation revealed good concordance of the cell distribution. As expected, eosinophils and IL-5 levels were significantly elevated in patients with asthma. Conclusions The hypothesis that sputum induction with a breath-controlled “smart” nebulizer is more efficient and different from an ultrasonic nebulizer was not confirmed. The Bland-Altman correlations showed good concordance when comparing the two devices. Trial registration NCT01543516 Retrospective registration date: March 5, 2012