Emilio Arteaga-Solis

Adiponectin Regulates Bone Mass via Opposite Central and Peripheral Mechanisms through FoxO1

The synthesis of adiponectin, an adipokine with ill-defined functions in animals fed a normal diet, is enhanced by the osteoblast-derived hormone osteocalcin. Here we show that adiponectin signals back in osteoblasts to hamper their proliferation and favor their apoptosis, altogether decreasing bone mass and circulating osteocalcin levels. Adiponectin fulfills these functions, independently of its known receptors and signaling pathways, by decreasing FoxO1 activity in a PI3-kinase-dependent manner. Over time, however, these local effects are masked because adiponectin signals in neurons of the locus coeruleus, also through FoxO1, to decrease the sympathetic tone, thereby increasing bone mass and decreasing energy expenditure. This study reveals that adiponectin has the unusual ability to regulate the same function in two opposite manners depending on where it acts and that it opposes, partially, leptins influence on the sympathetic nervous system. It also proposes that adiponectin regulation of bone mass occurs through a PI3-kinase-FoxO1 pathway.

Proteoglycan desulfation determines the efficiency of chondrocyte autophagy and the extent of FGF signaling during endochondral ossification

Cartilage extracellular matrix (ECM) contains large amounts of proteoglycans made of a protein core decorated by highly sulfated sugar chains, the glycosaminoglycans (GAGs). GAGs desulfation, a necessary step for their degradation, is exerted by sulfatases that are activated by another enzyme, Sulfatase-Modifying Factor 1 (SUMF1), whose inactivation in humans leads to severe skeletal abnormalities. We show here that despite being expressed in both osteoblasts and chondrocytes Sumf1 does not affect osteoblast differentiation. Conversely, in chondrocytes it favors ECM production and autophagy and promotes proliferation and differentiation by limiting FGF signaling. Thus, proteoglycan desulfation is a critical regulator of chondrogenesis.

Prenatal Polycyclic Aromatic Hydrocarbon, Adiposity, Peroxisome Proliferator-Activated Receptor (PPAR) γ Methylation in Offspring, Grand-Offspring Mice

Rationale Greater levels of prenatal exposure to polycyclic aromatic hydrocarbon (PAH) have been associated with childhood obesity in epidemiological studies. However, the underlying mechanisms are unclear. Objectives We hypothesized that prenatal PAH over-exposure during gestation would lead to weight gain and increased fat mass in offspring and grand-offspring mice. Further, we hypothesized that altered adipose gene expression and DNA methylation in genes important to adipocyte differentiation would be affected. Materials and Methods Pregnant dams were exposed to a nebulized PAH mixture versus negative control aerosol 5 days a week, for 3 weeks. Body weight was recorded from postnatal day (PND) 21 through PND60. Body composition, adipose cell size, gene expression of peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer-binding proteins (C/EBP) α, cyclooxygenase (Cox)-2, fatty acid synthase (FAS) and adiponectin, and DNA methylation of PPAR γ, were assayed in both the offspring and grand-offspring adipose tissue. Findings Offspring of dams exposed to greater PAH during gestation had increased weight, fat mass, as well as higher gene expression of PPAR γ, C/EBP α, Cox2, FAS and adiponectin and lower DNA methylation of PPAR γ. Similar differences in phenotype and DNA methylation extended through the grand-offspring mice. Conclusions Greater prenatal PAH exposure was associated with increased weight, fat mass, adipose gene expression and epigenetic changes in progeny.

Sulfatases are determinants of alveolar formation.

Alveolar formation or alveolarization is orchestrated by a finely regulated and complex interaction between growth factors and extracellular matrix proteins. The lung parenchyma contains various extracellular matrix proteins including proteoglycans, which are composed of glycosaminoglycans (GAGs) linked to a protein core. Although GAGs are known to regulate growth factor distribution and activity according to their degree of sulfation the role of sulfated GAG in the respiratory system is not well understood. The degree of sulfation of GAGs is regulated in part, by sulfatases that remove sulfate groups. In vertebrates, the enzyme Sulfatase-Modifying Factor 1 (Sumf1) activates all sulfatases. Here we utilized mice lacking Sumf1(-/-) to study the importance of proteoglycan desulfation in lung development. The Sumf1(-/-) mice have normal lungs up until the onset of alveolarization at post-natal day 5 (P5). We detected increased deposition of sulfated GAG throughout the lung parenchyma and a decrease in alveolar septa formation. Moreover, stereological analysis showed that the alveolar volume is 20% larger in Sumf1(-/-) as compared to wild type (WT) mice at P10 and P30. Additionally, pulmonary function test was consistent with increased alveolar volume. Genetic experiments demonstrate that in Sumf1(-/-) mice arrest of alveolarization is independent of fibroblast growth factor signaling. In turn, the Sumf1(-/-) mice have increased transforming growth factor β (TGFβ) signaling and in vivo injection of TGFβ neutralizing antibody leads to normalization of alveolarization. Thus, absence of sulfatase activity increases sulfated GAG deposition in the lungs causing deregulation of TGFβ signaling and arrest of alveolarization.

Ex vivo visualization of human ciliated epithelium and quantitative analysis of induced flow dynamics by using optical coherence tomography: EX VIVO VISUALIZATION OF HUMAN CILIATED EPITHELIUM

Cilia‐driven mucociliary clearance is an important self‐defense mechanism of great clinical importance in pulmonary research. Conventional light microscopy possesses the capability to visualize individual cilia and its beating pattern but lacks the throughput to assess the global ciliary activities and flow dynamics. Optical coherence tomography (OCT), which provides depth‐resolved cross‐sectional images, was recently introduced to this area.

Infant rhinitis and watery eyes predict school-age exercise-induced wheeze, emergency department visits and respiratory-related hospitalizations

BACKGROUND Rhinitis and conjunctivitis are often linked to asthma development through an allergic pathway. However, runny nose and watery eyes can result from nonallergic mechanisms. These mechanisms can also underlie exercise-induced wheeze (EIW), which has been associated with urgent medical visits for asthma, independent of other indicators of asthma severity or control. OBJECTIVE To test the hypothesis that rhinitis or watery eyes without cold symptoms (RWWC) in infancy predict development of EIW and urgent respiratory-related medical visits at school age, independent of seroatopy. METHODS Within a prospective birth cohort of low-income, urban children (n = 332), RWWC was queried during the first year of life. Relative risks (RRs) for EIW, emergency department (ED) visits, and hospitalizations for asthma and other breathing difficulties at 5 to 7 years of age were estimated with multivariable models. Seroatopy was determined at 7 years of age. RESULTS Infant RWWC was common (49% of children) and predicted school-age EIW (RR, 2.8; P < .001), ED visits (RR, 1.8; P = .001), and hospitalizations (RR, 9.8; P = .002). These associations were independent of infant wheeze. They were also independent of birth order, an indicator of increased risk of exposure to viruses in infancy, and infant ear infections, an indicator of sequelae of upper airway infections. The association between infant RWWC and ED visits at 5 to 7 years of age was attenuated (RR, 1.2; P = .23) when EIW at 5 to 7 years of age was included in the model, suggesting EIW mediates the association. Adjustment for seroatopy did not diminish the magnitudes of any of these associations. CONCLUSION These findings suggest a nonallergic connection between infant nonwheeze symptoms and important consequences of urban respiratory health by school age through EIW.

Associations between Parasympathetic Activity in the Month after Birth and Wheeze at Age 2–3 Years

Increased parasympathetic activity (PSA) has been implicated in airway hyperreactivity and asthma morbidity (1–3). In a prospective birth cohort study, we previously observed that rhinitis and watery eye symptoms in infancy, which in older children and adults can result from increased PSA, predicted future exercise-induced wheeze at school age; however, objective measures of PSA were not made in that study (4). In newborns and infants, PSA assessments can be made during sleep by heart rate (HR) and high-frequency HR variability (HF-HRV) measurements in the resting or basal state, and by responses to a head-up tilt challenge, which provokes vagal withdrawal and activation (5, 6). Measures of HRV differ as a function of sleep state (7). Infant sleep states (active/REM or quiet) can be classified based on respiratory rate variability with the use of a recently developed algorithm (8). Using a prospective birth cohort study, we tested the hypothesis that increased basal HF-HRV and responses to tilt in HR and HF-HRV assessed in the first month of life would be associated with report of wheeze at age 2–3 years. Children living in South Dakota were enrolled in the Safe Passage Study, which was designed to investigate prenatal risks for sudden infant death syndrome and stillbirth (9). Cardiorespiratory function was evaluated for newborns (12–96 h after birth) and/or at age 1 month. PSA was summarized using three measures of HR and HRV for these analyses (methods described in Reference 6). Briefly, basal HF-HRV was defined as the variation in HR within the normal range of infant breathing rates using spectral analyses during a 10-minute baseline period. An acute change in HR to a 458 head-up tilt test was defined as the maximum minus the minimum HR recorded during the first 15 seconds after reaching the head-up position (median of up to three tilts). A sustained HRV response to head-up tilt was defined as the median value during the 30-second period immediately before each tilt subtracted from the median value during the last minute in the head-up position (z45 s after reaching the head-up position). Results were analyzed for both active sleep (AS) and quiet sleep (QS) epochs, although not all infants had epochs of both states. Newborn data were used when valid measures were available for both newborns and 1-month-old infants. Parents of a subset of participants (n = 312) answered the following question when their child was 2–3 years old: “In the past year, has your child had wheezing or whistling in the chest?” Generalized estimating equations were used to calculate the relative risk (RR) of wheeze at age 2–3 for an interquartile range increase in HRV measures, controlling for potential confounders and covariates. Of the 312 children, 22% had a report of wheeze at age 2–3 years. Wheeze was more common among boys than among girls (29% vs. 16%; P = 0.005). There was no significant difference in wheeze by race or exposure to prenatal alcohol or tobacco smoke (all P . 0.3). Among the 312 infants, HRV measures were available for AS and QS in n = 282 and n = 139 children, respectively. HR and HRV responses to tilt were available for AS and QS in n = 254 and n = 178 children, respectively. The prevalence of wheeze at age 2–3 years did not differ significantly (P . 0.05) among children with data for AS and QS. There were no associations between any of the HRV measures for AS and wheeze at age 2–3 years (Table 1). In a model adjusting for sex, gestational age, fetal alcohol and tobacco exposure, and study location, PSA-mediated changes in acute HR and sustained HRV in QS after the tilt challenge predicted wheeze at age 2–3 (Table 1). Inclusion of birth order (an indicator of risk of infection) in the models did not alter the effect estimates (i.e., a ,10% difference). The association with acute changes in HR appeared to be present among girls (RR, 2.6 [95% confidence interval, 1.3–5.3]; P = 0.006) but not boys (RR, 1.2 [0.62–2.3]; P = 0.60) (Pinteraction = 0.023; bivariate associations depicted in Figure 1). Our hypothesis of an association between altered PSA in infancy and subsequent asthma was based on findings from our New York City birth cohort, where we observed that infants with rhinitis or watery eye symptoms in the absence of a cold were more likely to have exercise-induced wheeze, emergency department visits, and hospitalizations for asthma and other breathing problems when they reached school age (4). This association was independent of allergic sensitization and suggested a PSA connection between rhinitis or watery eyes in infancy and subsequent bronchoconstriction. The findings we report here offer some support for this connection, at least with regard to a preschool-age wheeze outcome. It is also compelling that the association between HR responses to tilt in newborns and wheeze in toddlers was only observed among girls. Increasingly, asthma is being conceptualized to be caused by complex heterogeneous pathological processes, some of which are independent of allergic inflammation but dependent on sex (10). One limitation of this study is that wheeze (the result of airway narrowing) at age 2–3 years has multiple causes, some of which Supported by NIH grants U01/HD045935, U01HD055155-10, UG3AI02327901 and UG3 OD023279 (Environmental Influences on Child Health Outcomes program), and P30 ES09089.

Visualization of ex vivo human ciliated epithelium and induced flow using optical coherence tomography (Conference Presentation)

The ciliated epithelium is important to the human respiratory system because it clears mucus that contains harmful microorganisms and particulate matter. We report the ex vivo visualization of human trachea/bronchi ciliated epithelium and induced flow characterized by using spectral-domain optical coherence tomography (SD-OCT). A total number of 17 samples from 7 patients were imaged. Samples were obtained from Columbia University Department of Anesthesiology’s tissue bank. After excision, the samples were placed in Gibco Medium 199 solution with oxygen at 4°C until imaging. The samples were maintained at 36.7°C throughout the experiment. The imaging protocol included obtaining 3D volumes and 200 consecutive B-scans parallel to the head-to-feet direction (superior-inferior axis) of the airway, using Thorlabs Telesto system at 1300 nm at 28 kHz A-line rate and a custom built high resolution SDOCT system at 800nm at 32 kHz A-line rate. After imaging, samples were processed with H and E histology. Speckle variance of the time resolved datasets demonstrate significant contrast at the ciliated epithelium sites. Flow images were also obtained after injecting 10μm polyester beads into the solution, which shows beads traveling trajectories near the ciliated epithelium areas. In contrary, flow images taken in the orthogonal plane show no beads traveling trajectories. This observation is in line with our expectation that cilia drive flow predominantly along the superior-inferior axis. We also observed the protective function of the mucus, shielding the epithelium from the invasion of foreign objects such as microspheres. Further studies will be focused on the cilia’s physiological response to environmental changes such as drug administration and physical injury.