1 September 2015 in Research in Microbiology
1 March 2018 in Arteriosclerosis, Thrombosis, and Vascular Biology
Objective—: Inhibition of mineral crystal formation is a crucial step in ectopic calcification. Serum calciprotein particles (CPPs) have been linked to chronic kidney disease (CKD) calcification propensity, but additional knowledge is required to understand their function, assemblage, and composition. The role of other circulating nanostructures, such as extracellular vesicles (EVs) in vascular calcification is currently unknown. Here, we investigated the association of GRP (Gla-rich protein) with circulating CPP and EVs and the role of CKD CPPs and EVs in vascular calcification. Approach and Results—: Biological CPPs and EVs were isolated from healthy and CKD patients and comparatively characterized using ultrastructural, analytic, molecular, and immuno-based techniques. Our results show that GRP is a constitutive component of circulating CPPs and EVs. CKD stage 5 serum CPPs and EVs are characterized by lower levels of fetuin-A and GRP, and CPPs CKD stage 5 have increased mineral maturation, resembling secondary CPP particles. Vascular smooth muscle cell calcification assays reveal that CPPs CKD stage 5 and EVs CKD stage 5 are taken up by vascular smooth muscle cells and induce vascular calcification by promoting cell osteochondrogenic differentiation and inflammation. These effects were rescued by incubation of CPPs CKD stage 5 with γ-carboxylated GRP. In vitro, formation and maturation of basic calcium phosphate crystals was highly reduced in the presence of γ-carboxylated GRP, fetuin-A, and MGP (matrix gla protein), and a similar antimineralization system was identified in vivo. Conclusions—: Uremic CPPs and EVs are important players in the mechanisms of widespread calcification in CKD. We propose a major role for cGRP as inhibitory factor to prevent calcification at systemic and tissue levels.
15 February 2013 in Journal of Toxicology and Environmental Health, Part A
Farmers are occupationally exposed to many respiratory hazards at work and display higher rates of asthma and respiratory symptoms than other workers. Dust is one of the components present in poultry production that increases risk of adverse respiratory disease occurrence. Dust originates from poultry residues, molds, and feathers and is biologically active as it contains microorganisms. Exposure to dust is known to produce a variety of clinical responses, including asthma, chronic bronchitis, chronic airways obstructive disease (COPD), allergic alveolitis, and organic dust toxic syndrome (ODTS). A study was developed to determine particle contamination in seven poultry farms and correlate this with prevalence rate of respiratory defects and record by means of a questionnaire the presence of clinical symptoms associated with asthma and other allergy diseases by European Community Respiratory Health Survey. Poultry farm dust contamination was found to contain higher concentrations of particulate matter (PM) PM5 and PM10. Prevalence rate of obstructive pulmonary disorders was higher in individuals with longer exposure regardless of smoking status. In addition, a high prevalence for asthmatic (42.5%) and nasal (51.1%) symptoms was noted in poultry workers. Data thus show that poultry farm workers are more prone to suffer from respiratory ailments and this may be attributed to higher concentrations of PM found in the dust. Intervention programs aimed at reducing exposure to dust will ameliorate occupational working conditions and enhance the health of workers.
1 February 2015 in Arteriosclerosis, Thrombosis, and Vascular Biology
Objective—: Vascular and valvular calcifications are pathological processes regulated by resident cells, and depending on a complex interplay between calcification promoters and inhibitors, resembling skeletal metabolism. Here, we study the role of the vitamin K–dependent Gla-rich protein (GRP) in vascular and valvular calcification processes. Approach and Results—: Immunohistochemistry and quantitative polymerase chain reaction showed that GRP expression and accumulation are upregulated with calcification simultaneously with osteocalcin and matrix Gla protein (MGP). Using conformation-specific antibodies, both γ-carboxylated GRP and undercarboxylated GRP species were found accumulated at the sites of mineral deposits, whereas undercarboxylated GRP was predominant in calcified aortic valve disease valvular interstitial cells. Mineral-bound GRP, MGP, and fetuin-A were identified by mass spectrometry. Using an ex vivo model of vascular calcification, γ-carboxylated GRP but not undercarboxylated GRP was shown to inhibit calcification and osteochondrogenic differentiation through α-smooth muscle actin upregulation and osteopontin downregulation. Immunoprecipitation assays showed that GRP is part of an MGP–fetuin-A complex at the sites of valvular calcification. Moreover, extracellular vesicles released from normal vascular smooth muscle cells are loaded with GRP, MGP, and fetuin-A, whereas under calcifying conditions, released extracellular vesicles show increased calcium loading and GRP and MGP depletion. Conclusions—: GRP is an inhibitor of vascular and valvular calcification involved in calcium homeostasis. Its function might be associated with prevention of calcium-induced signaling pathways and direct mineral binding to inhibit crystal formation/maturation. Our data show that GRP is a new player in mineralization competence of extracellular vesicles possibly associated with the fetuin-A–MGP calcification inhibitory system. GRP activity was found to be dependent on its γ-carboxylation status, with potential clinical relevance.