Cigarette smoke extract induces a phenotypic shift in epithelial cells: involvement of HIF1α in mesenchymal transition

In COPD, matrix remodeling contributes to airflow limitation. Recent evidence suggests that next to fibroblasts, the process of epithelial-mesenchymal transition can contribute to matrix remodeling. CSE has been shown to induce EMT in lung epithelial cells, but the signaling mechanisms involved are largely unknown and subject of this study. EMT was assessed in A549 and BEAS2B cells stimulated with CSE by qPCR, Western blotting and immunofluorescence for epithelial and mesenchymal markers, as were collagen production, cell adhesion and barrier integrity as functional endpoints. Involvement of TGF-beta and HIF1 alpha signaling pathways were investigated. In addition, mouse models were used to examine the effects of CS on hypoxia signaling and of hypoxia per se on mesenchymal expression. CSE induced EMT characteristics in A549 and BEAS2B cells, evidenced by decreased expression of epithelial markers and a concomitant increase in mesenchymal marker expression after CSE exposure. Furthermore cells that underwent EMT showed increased production of collagen, decreased adhesion and disrupted barrier integrity. The induction of EMT was found to be independent of TGF-beta signaling. On the contrary, CS was able to induce hypoxic signaling in A549 and BEAS2B cells as well as in mice lung tissue. Importantly, HIF1 alpha knock-down prevented induction of mesenchymal markers, increased collagen production and decreased adhesion after CSE exposure, data that are in line with the observed induction of mesenchymal marker expression by hypoxia in vitro and in vivo. Together these data provide evidence that both bronchial and alveolar epithelial cells undergo a functional phenotypic shift in response to CSE exposure which can contribute to increased collagen deposition in COPD lungs. Moreover, HIF1 alpha signaling appears to play an important role in this process

Sex Differences in the Brain: A Whole Body Perspective

Most writing on sexual differentiation of the mammalian brain (including our own) considers just two organs: the gonads and the brain. This perspective, which leaves out all other body parts, misleads us in several ways. First, there is accumulating evidence that all organs are sexually differentiated, and that sex differences in peripheral organs affect the brain. We demonstrate this by reviewing examples involving sex differences in muscles, adipose tissue, the liver, immune system, gut, kidneys, bladder, and placenta that affect the nervous system and behavior. The second consequence of ignoring other organs when considering neural sex differences is that we are likely to miss the fact that some brain sex differences develop to compensate for differences in the internal environment (i.e., because male and female brains operate in different bodies, sex differences are required to make output/function more similar in the two sexes). We also consider evidence that sex differences in sensory systems cause male and female brains to perceive different information about the world; the two sexes are also perceived by the world differently and therefore exposed to differences in experience via treatment by others. Although the topic of sex differences in the brain is often seen as much more emotionally charged than studies of sex differences in other organs, the dichotomy is largely false. By putting the brain firmly back in the body, sex differences in the brain are predictable and can be more completely understood

Tissue specificity of mitochondrial adaptations in rats after 4 weeks of normobaric hypoxia

Purpose Exposure to hypoxia has been suggested to activate multiple adaptive pathways so that muscles are better able to maintain cellular energy homeostasis. However, there is limited research regarding the tissue specificity of this response. The aim of this study was to investigate the influence of tissue specificity on mitochondrial adaptations of rat skeletal and heart muscles after 4 weeks of normobaric hypoxia (FiO2: 0.10). Methods Twenty male Wistar rats were randomly assigned to either normobaric hypoxia or normoxia. Mitochondrial respiration was determined in permeabilised muscle fibres from left and right ventricles, soleus and extensorum digitorum longus (EDL). Citrate synthase activity and the relative abundance of proteins associated with mitochondrial biogenesis were also analysed. Results After hypoxia exposure, only the soleus and left ventricle (both predominantly oxidative) presented a greater maximal mass-specific respiration (+48 and +25%, p \u3c 0.05) and mitochondrial-specific respiration (+75 and +28%, p \u3c 0.05). Citrate synthase activity was higher in the EDL (0.63 ± 0.08 vs 0.41 ± 0.10 μmol min− 1 μg− 1) and lower in the soleus (0.65 ± 0.17 vs 0.87 ± 0.20 μmol min− 1 μg− 1) in hypoxia with respect to normoxia. There was a lower relative protein abundance of PGC-1α (−25%, p \u3c 0.05) in the right ventricle and a higher relative protein abundance of PGC-1β (+43%, p \u3c 0.05) in the left ventricle of rats exposed to hypoxia, with few differences for protein abundance in the other muscles. Conclusion Our results show a muscle-specific response to 4 weeks of normobaric hypoxia. Depending on fibre type, and the presence of ventricular hypertrophy, muscles respond differently to the same degree of environmental hypoxia

Phenotypic and metabolic features of mouse diaphragm and gastrocnemius muscles in chronic lung carcinogenesis: influence of underlying emphysema

Background: Muscle wasting negatively impacts the progress of chronic diseases such as lung cancer (LC) and emphysema, which are in turn interrelated. Objectives: We hypothesized that muscle atrophy and body weight loss may develop in an experimental mouse model of lung carcinogenesis, that the profile of alterations in muscle fiber phenotype (fiber type composition and morphometry, muscle structural alterations, and nuclear apoptosis), and in muscle metabolism are similar in both respiratory and limb muscles of the tumor-bearing mice, and that the presence of underlying emphysema may influence those events. Methods: Diaphragm and gastrocnemius muscles of mice with urethane-induced lung cancer (LC-U) with and without elastase-induced emphysema (E–U) and non-exposed controls (N = 8/group) were studied: fiber type composition, morphometry, muscle abnormalities, apoptotic nuclei (immunohistochemistry), and proteolytic and autophagy markers (immunoblotting) at 20- and 35-week exposure times. In the latter cohort, structural contractile proteins, creatine kinase (CK), peroxisome proliferator-activated receptor (PPAR) expression, oxidative stress, and inflammation were also measured. Body and muscle weights were quantified (baseline, during follow-up, and sacrifice). Results: Compared to controls, in U and E–U mice, whole body, diaphragm and gastrocnemius weights were reduced. Additionally, both in diaphragm and gastrocnemius, muscle fiber cross-sectional areas were smaller, structural abnormalities, autophagy and apoptotic nuclei were increased, while levels of actin, myosin, CK, PPARs, and antioxidants were decreased, and muscle proteolytic markers did not vary among groups. Conclusions: In this model of lung carcinogenesis with and without emphysema, reduced body weight gain and muscle atrophy were observed in respiratory and limb muscles of mice after 20- and 35-week exposure times most likely through increased nuclear apoptosis and autophagy. Underlying emphysema induced a larger reduction in the size of slow- and fast-twitch fibers in the diaphragm of U and E–U mice probably as a result of the greater inspiratory burden imposed onto this muscle.This study has been supported by CIBERES, RTICC RD12/0036/0040, PI07/0751 (FEDER), PI11/02029 (FEDER), PI13/08006 (FEDER), PI14/00713 (FEDER), and MINECO DPI2015-64221-C2-2 SEPAR 2009. None of the funding bodies have played any role in the data collection, analysis, interpretation of the results, or manuscript writing