DNA methylation biomarkers in asthma and rhinitis: Are we there yet?

The study of epigenetics has improved our understanding of mechanisms underpinning gene-environment interactions and is providing new insights in the pathophysiology of respiratory allergic diseases. We reviewed the literature on DNA methylation patterns across different tissues in asthma and/or rhinitis and attempted to elucidate differentially methylated loci that could be used to characterize asthma or rhinitis. Although nasal and bronchial epithelia are similar in their histological structure and cellular composition, genetic and epigenetic regulation may differ across tissues.

Differential Effects of Toll-Like Receptor Activation and Differential Mediation by MAP Kinases of Immune Responses in Microglial Cells.

Microglial activation is believed to play a role in many psychiatric and neurodegenerative diseases. Based largely on evidence from other cell types, it is widely thought that MAP kinase (ERK, JNK and p38) signalling pathways contribute strongly to microglial activation following immune stimuli acting on toll-like receptor (TLR) 3 or TLR4. We report here that exposure of SimA9 mouse microglial cell line to immune mimetics stimulating TLR4 (lipopolysaccharide-LPS) or TLR7/8 (resiquimod/R848), results in marked MAP kinase activation, followed by induction of nitric oxide synthase, and various cytokines/chemokines.

1997 William J. Stickel Gold Award. Morphological and biochemical properties of metatarsophalangeal joint cartilage.

Although there is sparse information concerning the properties of foot-joint cartilages, knowledge of the morphology and biochemistry of these cartilages is important in the study of changes that occur in the development of osteoarthritis. Normal first and fifth metatarsophalangeal joints were chosen for comparison because of the difference between these two joints in the prevalence of osteoarthritis, particularly with advancing age. The authors' study shows that there is no age-related decrease in articular-cartilage thickness; however, there is an age-related decrease in the chondrocyte density in the superficial zone in both joints.

Interleukin-1alpha and beta in growth plate cartilage are regulated by vitamin D metabolites in vivo.

Matrix remodeling plays a prominent role in growth plate calcification. Since interleukin-1 (IL-1) has been implicated in stimulating proteinase production and inhibiting matrix synthesis in articular cartilage, we examined whether IL-1 was present in growth plate and whether the vitamin D metabolites, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3; 1,25) and 24,25(OH)2D3 (24,25), regulate the level of IL-1 found in this tissue. Sprague-Dawley rats were placed on normal (Normal rats) or rachitogenic diet (-VDP rats).

Articular cartilage. Part II. The osteoarthritic joint.

Articular hyaline cartilage, though a metabolically active tissue, has limited capacity for repair. Though the integrity of the cartilage is dependent upon a certain level of force placed upon it, excessive force leads to damage. It is when the breakdown of the cartilage exceeds the capacity of the cartilage for repair that osteoarthritis results.

Articular cartilage. Part I. The normal joint.

Articular hyaline cartilage is of interest to both the clinician and the basic scientist because of its unique physical and chemical properties which are a consequence of its biochemical composition. Although it is a tissue which is hypocellular, avascular, and also lacks nerves and lymphatics, it is active in synthesis and degradation. Articular cartilage responds to the forces to which it is subjected and, in this way, maintains its integrity as long as those forces do not exceed the tissue's capacity for repair or permanently change the biologic response of the cells.

Effects of antirheumatic drugs on the interleukin-1 alpha induced synthesis and activation of proteinases in articular cartilage explants in culture.

Three human cytokines (interleukin-1 alpha, interleukin-1 beta and tumor necrosis factor-alpha), added into the medium of bovine or rabbit articular cartilage explant cultures, stimulated the synthesis and activation of various proteinases. Proteoglycan degradation, measured by assaying for sulfated glycosaminoglycans released into the medium, was correlated with the proteinase stimulation. Several antirheumatic drugs were tested in a similar tissue culture system as potential inhibitors of the interleukin-1 alpha mediated stimulation of proteinase and PGE2 syntheses.

Isolation and partial characterization of neutrophil elastase inhibitors from bovine vitreous and aorta.

Bovine vitreous body and aorta contain extractable leukocyte elastase inhibitors, which were purified by gel filtration and affinity chromatography on agarose-pancreatic elastase. The purified inhibitor preparation from aorta was resolved by polyacrylamide gel electrophoresis into a main band migrating slightly faster than commercial Trasylol and a more weakly stained band migrating close to chymotrypsinogen. The purified inhibitor preparation from both sources inhibited, in a competitive fashion, purified human leukocyte elastase and was ineffective against bovine trypsin and leukocyte cathepsin G or collagenase.

Connective tissue degradation by invasive rat bladder carcinomas: action of nonspecific proteinases on collagenous matrices.

The invasive RBTCC-8 rat bladder carcinoma cell line (passage number, greater than 100) and its derivates, the RBTCC-8 tumor isografts and the 1-RBTCC-8 daughter cell line (fourth passage), express proteolytic activities of broad substrate specificity, which allow them to efficiently degrade extracellular (collagenous) matrices. Cell-associated, collagenolytic activity is evidenced by the release of hydroxyproline from collagen substrates of types I and IV, by visualizing the low-molecular-weight collagen breakdown products on sodium dodecyl sulfate-polyacrylamide gels, and by the depth of invasion into extracellular matrices in our bone invasion assays. Fractionated by diethylaminoethyl column chromatography, the major collagenolytic activities against collagens of types I and IV coelute in a relatively narrow peak within a NaCl gradient.

Presence of fibronectin in articular cartilage in two animal models of osteoarthritis.

Fibronectin content was determined in articular cartilage in a spontaneous dog model and in a meniscectomy rabbit model of osteoarthritis. Determination of the fibronectin content of urea extracts of articular cartilage by an enzyme linked immunosorbent assay (ELISA) disclosed that degenerated cartilage contained from 10- to 40-fold more fibronectin than normal cartilage. The finding that cartilage fibronectin content was increased in both animal models suggests that elevated cartilage fibronectin content is a general feature of the osteoarthritic process.

Degradation of cartilage matrix by purified elastase and its control by an endogenous purified specific cartilage elastase inhibitor.

Unlabelled: We report here that an endogenous protein in cartilage is capable of inhibiting leukocyte elastase degradation of cartilage matrix. This inhibitor is specific for elastase. After 30 min of incubation, small amounts of the purified elastase are capable of releasing relatively large amounts of uronic acid positive material and relatively small amounts of collagenous and noncollagenous protein.

Identification, characterization and localization of a (Ca2+ + Mg2+)-activated purine nucleoside triphosphate phosphohydrolase from calcifying cartilage.

A purine nucleoside triphosphate phosphohydrolase (unspecified diphosphate phosphohydrolase, EC 3.6.1.

Studies on the mechanism of callus cartilage differentiation and calcification during fracture healing.

The morphologic and biochemical events during fracture callus cartilage differentiation and calcification are presented. 1. Histologic studies have demonstrated that unimmobilized fractures heal through endochondral ossification.

The differentiation and calcification of chondrocytes in primary cell cultures.

The cartilage from a non-immobilized fracture undergoes a series of morphological and biochemical changes resembling the in vivo differentiation and calcification in the epiphyseal plate. The studies reported here demonstrate that a homogeneous population of chondrocytes isolated from fracture callus fibrocartilage undergoes the same changes in vitro. Chondrocyte primary cultures were grown for 28 days during which time the morphological, histological and histochemical properties of the cultures were studied.

The ultrastructural cytology and chemical composition of fracture callus cartilage.

The differentiation and calcification of fracture callus cartilage studied by light microscopy resembles that of the epiphyseal plate cartilage. In this study, a correlation between the ultrastructural cytology and the chemical composition of the various cartilage types found in fracture callus was attempted. Fibrocartilage cells were very active with profuse secretion of collagen into the matrix.

Resolution, specificity and transphosphorylase activity of calcifying cartilage alkaline phosphatases.

The phosphate releasing activity from calf scapula cartilage was resolved by DEAE-cellulose chromatography into two distinct phosphatase activities. The activity eluted first from the column (phosphatase I) was active towards a variety of phosphate esters and several linear oligo phosphates including sodium pyrophosphate, while the second phosphatase activity (phosphatase II) was active only towards simple phosphate esters. Phosphatase I acted towards oligo phosphates in a stepwise fashion hydrolyzing one phosphate at a time.

Resolution, purification and characterization of the orthophosphate releasing activities from fracture callus calcifying cartilage.

Callus calcifying cartilage alkaline phosphatase was resolved by DEAE-cellulose column chromatography into two distinct phsophatase activities. The phosphatase activity which was eluted first from the column, (phosphatase I), was active towards a variety of phosphate esters, sodium pyrophosphatase and several linear polyphosphates, while the second phosphatase activity , (phosphatase II), was active toward simple phosphate esters but not towards sodium pyrophosphate and linear oligo or polyphosphates. All the phosphate esters, sodium pyrophosphate and polyphosphates at higher concentrations were inhibitory for phosphatase I.