ABSTRACT
Optimal fetal lung growth requires anion-driven fluid secretion into the lumen of the developing organ. The fetus is hypercalcemic compared to the mother and here we show that in the developing human lung this hypercalcaemia acts on the extracellular calcium-sensing receptor, CaSR, to promote fluid-driven lung expansion through activation of the cystic fibrosis transmembrane conductance regulator, CFTR. Several chloride channels including TMEM16, bestrophin, CFTR, CLCN2 and CLCA1, are also expressed in the developing human fetal lung at gestational stages when CaSR expression is maximal. Measurements of Cl(-)-driven fluid secretion in organ explant cultures show that pharmacological CaSR activation by calcimimetics stimulates lung fluid secretion through CFTR, an effect which in humans, but not mice, was also mimicked by fetal hypercalcemic conditions, demonstrating that the physiological relevance of such a mechanism appears to be species-specific. Calcimimetics promote CFTR opening by activating adenylate cyclase and we show that Ca(2+)-stimulated type I adenylate cyclase is expressed in the developing human lung. Together, these observations suggest that physiological fetal hypercalcemia, acting on the CaSR, promotes human fetal lung development via cAMP-dependent opening of CFTR. Disturbances in this process would be expected to permanently impact lung structure and might predispose to certain postnatal respiratory diseases.
Subject(s)
Cystic Fibrosis Transmembrane Conductance Regulator/metabolism , Fetal Organ Maturity , Lung/embryology , Lung/metabolism , Organogenesis , Receptors, Calcium-Sensing/metabolism , Adenylyl Cyclases/metabolism , Animals , Anoctamin-1 , Bestrophins , Chloride Channels/genetics , Chloride Channels/metabolism , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Extracellular Space , Eye Proteins/metabolism , Fetus , Gene Expression Regulation, Developmental , Humans , Hypercalcemia/genetics , Hypercalcemia/metabolism , Immunohistochemistry , Ion Channel Gating , Ion Channels/metabolism , Mice , Models, BiologicalABSTRACT
Considerable evidence shows a key role for protein modification in the adverse effects of chemicals; however, the interaction of diesel exhaust particles (DEP) with proteins and the resulting biological activity remains unclear. DEP and carbon black (CB) suspensions with and without bovine serum albumin (BSA) were used to elucidate the biological effects of air pollutants. The DEP and CB samples were then divided into suspensions and supernatants. Two important goals of the interaction of DEP with BSA were as follows: (1) understanding BSA modification by particles and (2) investigating the effects of particles bound with BSA and the corresponding supernatants on cellular oxidative stress and inflammation. We observed significant free amino groups production was caused by DEP. Using liquid chromatography-mass spectrometry (LC-MS), we observed that BSA was significantly oxidised by DEP in the supernatants and that the peptides ETYGDMADCCEK, MPCTEDYLSLILNR and TVMENFVAFVDK, derived BSA-DEP conjugates, were also oxidised. In A549 cells, DEP-BSA suspensions and the corresponding supernatants reduced 8-hydroxy-2'-deoxyguanosine (8-OHdG) production and increased interleukin-6 (IL-6) levels when compared to DEP solutions without BSA. Our findings suggest that oxidatively modified forms of BSA caused by DEP could lead to oxidative stress and the activation of inflammation.
Subject(s)
Air Pollutants/chemistry , Serum Albumin, Bovine/chemistry , Vehicle Emissions/analysis , 8-Hydroxy-2'-Deoxyguanosine , Air Pollutants/toxicity , Amino Acid Sequence , Animals , Cattle , Cell Line, Tumor , Chromatography, High Pressure Liquid , Deoxyguanosine/analogs & derivatives , Deoxyguanosine/metabolism , Humans , Interleukin-6/metabolism , Mass Spectrometry , Oxidation-Reduction , Oxidative Stress/drug effects , Peptides/analysis , Peptides/chemistry , Serum Albumin, Bovine/metabolism , Serum Albumin, Bovine/pharmacology , Vehicle Emissions/toxicityABSTRACT
BACKGROUND: Silver nanoparticles (AgNPs) have been associated with the exacerbation of asthma; however, the immunological basis for the adjuvant effects of AgNPs is not well understood. OBJECTIVE: The aim of the study reported here was to investigate the allergic effects of AgNP inhalation using proteomic approaches. METHODS: Allergen provoked mice were exposed to 33 nm AgNPs at 3.3 mg/m(3). Following this, bronchoalveolar lavage fluid (BALF) and plasma were collected to determine protein profiles. RESULTS: In total, 106 and 79 AgNP-unique proteins were identified in the BALF of control and allergic mice, respectively. Additionally, 40 and 26 AgNP-unique proteins were found in the plasma of control and allergic mice, respectively. The BALF and plasma protein profiles suggested that metabolic, cellular, and immune system processes were associated with pulmonary exposure to AgNPs. In addition, we observed 18 proteins associated with systemic lupus erythematosus that were commonly expressed in both control and allergic mice after AgNP exposure. Significant allergy responses were observed after AgNP exposure in control and allergic mice, as determined by ovalbumin-specific immunoglobulin E. CONCLUSION: Inhaled AgNPs may regulate immune responses in the lungs of both control and allergic mice. Our results suggest that immunology is a vital response to AgNPs.
