Real-world registry-based study on apremilast use in psoriasis and psoriatic arthritis in Finland.

Objectives: This study assessed the position of apremilast in the treatment pathway of psoriasis (PsO) and psoriatic arthritis (PsA) in Finnish clinical practice, compared the characteristics of apremilast and biologic therapy users, evaluated persistence with apremilast and identified factors influencing treatment discontinuation.

Method: This retrospective study used data from Finnish national health registries. The target group was identified based on L40* diagnosis and medication records between 2015 and 2018.

Novel perspectives on the transcytotic route in osteoclasts.

We analyzed the characteristics of degraded bone matrix-delivering vesicles along the transcytotic route from the ruffled border to the functional secretory domain (FSD) in bone-penetrating osteoclasts. Cells of rat or human origin were cultured on bovine bone slices and analyzed via confocal microscopy. Helix pomatia lectin binding indicated that transcytotic vesicles expose aberrant N-acetylgalactosamine glycoconjugates, which is associated with a poor prognosis for a range of metastasizing human adenocarcinomas.

Osteoclast ruffled border has distinct subdomains for secretion and degraded matrix uptake.

Subosteoclastic bone resorption is a result of HCl and proteinase secretion through a late endosome-like bone facing membrane domain called ruffled border. As bone matrix is degraded, it enters osteoclasts' transcytotic vesicles for further processing and is then finally exocytosed to the intercellular space. The present study clarifies the spatial relationship between these vesicle fusion and matrix uptake processes at the ruffled border.

PYK2 autophosphorylation, but not kinase activity, is necessary for adhesion-induced association with c-Src, osteoclast spreading, and bone resorption.

Proline-rich tyrosine kinase 2 (PYK2) is the main adhesion-induced kinase in bone-resorbing osteoclasts. Previous studies have shown that ligation of alpha(v)beta(3) integrin in osteoclasts induces c-Src-dependent tyrosine phosphorylation and PYK2 activation, leading to cytoskeletal rearrangement, migration, and polarization of these cells. In this study, we examined the role of PYK2 kinase activity and its major autophosphorylation site in adhesion-dependent signaling and cytoskeletal organization during osteoclast spreading and migration.

Alendronate inhibits invasion of PC-3 prostate cancer cells by affecting the mevalonate pathway.

Breast and prostate cancer preferentially metastasize in the skeleton, inducing locally increased bone resorption by osteoclasts. Bisphosphonates (BPs), potent inhibitors of osteoclasts and bone resorption, are able to reduce metastatic bone lesions, but the metastasis-related cellular target molecules for BPs have not yet been identified. In osteoclasts, nitrogen-containing BPs inhibit the function of the mevalonate pathway, impairing the prenylation and activation of small GTPases.

Enhanced invasion and tumor growth of fibroblast growth factor 8b-overexpressing MCF-7 human breast cancer cells.

Fibroblast growth factor 8 (FGF-8) is a secreted heparin-binding protein, which has mitogenic and transforming activity. Increased expression of FGF-8 has been found in human breast cancer, and it has a potential autocrine role in its progression. Human FGF-8 is alternatively spliced to generate four protein isoforms (a, b, e, and f).

Abnormal localisation and hyperclustering of (alpha)(V)(beta)(3) integrins and associated proteins in Src-deficient or tyrphostin A9-treated osteoclasts.

The non-receptor tyrosine kinase Src was shown to be essential for osteoclast function in vivo. We have previously reported that engagement of (alpha)(v)(beta)(3) integrin in osteoclasts induces tyrosine phosphorylation and activation of the adhesion kinase PYK2 and the adaptor protein p130(Cas) in a Src-dependent manner. The objective of this study was to analyse the role of c-Src in the (alpha)(v)(beta)(3) integrin-dependent recruitment of signalling and cytoskeletal molecules in osteoclasts during bone resorption.

Inhibition of osteoclast function by adenovirus expressing antisense protein-tyrosine kinase 2.

Osteoclast activation is initiated by adhesion to bone, cytoskeletal rearrangement, formation of the sealing zone, and formation of the polarized ruffled membrane. Previous findings suggest that protein-tyrosine kinase 2 (PYK2), a cytoplasmic kinase related to focal adhesion kinase, participates in these events. This study examines the role of PYK2 in adhesion-mediated signaling and osteoclast function, using PYK2 antisense.

Integrins and signaling in osteoclast function.

Integrins are heterodimeric adhesion receptors that mediate cell-matrix and cell-cell interactions. Osteoclasts highly express the alphavbeta3 integrin, which binds to a variety of extracellular matrix proteins including vitronectin, osteopontin and bone sialoprotein. RGD-containing peptides, RGD-mimetics and alphavbeta3 blocking antibodies inhibit bone resorption in vitro and in vivo, suggesting that this integrin plays an important role in osteoclast function.

Role of alpha(v)beta(3) integrin in osteoclast migration and formation of the sealing zone.

The alpha(v)beta(3) integrin is abundantly expressed in osteoclasts and has been implicated in the regulation of osteoclast function, especially in cell attachment. However, in vivo studies have shown that echistatin, an RGD-containing disintegrin which binds to alpha(v)beta(3), inhibits bone resorption without changing the number of osteoclasts on the bone surface, suggesting inhibition of osteoclast activity. The objective of this study was to examine how occupancy of alpha(v)beta(3) integrins inhibits osteoclast function, using primary rat osteoclasts and murine pre-fusion osteoclast-like cells formed in a co-culture system.

Stable association of PYK2 and p130(Cas) in osteoclasts and their co-localization in the sealing zone.

Bone resorption is initiated by osteoclast attachment to the mineralized matrix, cytoskeletal reorganization, cellular polarization, and the formation of the sealing zone. The present study examines the interaction between PYK2 and p130(Cas) (Crk-associated substrate), suggested to be part of the signaling pathway initiated by osteoclast adhesion. Using murine osteoclast-like cells (OCLs) and their mononuclear precursors (pOCs), generated in a co-culture of bone marrow and osteoblastic MB1.

PYK2 in osteoclasts is an adhesion kinase, localized in the sealing zone, activated by ligation of alpha(v)beta3 integrin, and phosphorylated by src kinase.

Osteoclast activation is initiated by adhesion to the bone surface, followed by cytoskeletal rearrangement, the formation of the sealing zone, and a polarized ruffled membrane. This study shows that PYK2/CAKbeta/RAFTK, a cytoplasmic kinase related to the focal adhesion kinase, is highly expressed in rat osteoclasts in vivo. Using murine osteoclast-like cells (OCLs) or their mononuclear precursors (pOCs), generated in a coculture of bone marrow and osteoblastic MB1.

Inhibition of bone resorption in vitro by a peptide containing the cadherin cell adhesion recognition sequence HAV is due to prevention of sealing zone formation.

Cadherins are transmembrane glycoproteins usually mediating homophilic calcium-dependent cell-cell adhesion in a variety of cells and species. All classical cadherins share common structural and functional properties, one of which is the cell adhesion recognition (CAR) sequence HAV (His-Ala-Val). In the present work we have studied the effects of the cadherin CAR sequence-containing hexapeptide AHAVSE on osteoclasts, the main bone resorbing cells in well-characterized pit formation assay.

Phosphatidylinositol 3-kinase association with the osteoclast cytoskeleton, and its involvement in osteoclast attachment and spreading.

Osteoclast activation involves attachment to the mineralized bone matrix and reorganization of the cytoskeleton, leading to polarization of the cell. Signaling molecules, PI3-kinase, rho A, and pp60c-src, were shown to be essential for osteoclastic bone resorption. In this study we have focused on the involvement of these signaling molecules in the early event of osteoclast activation: attachment, spreading, and organization of the cytoskeleton.

Beta 1 integrins and osteoclast function: involvement in collagen recognition and bone resorption.

The extracellular matrix of bone is composed mainly of type I collagen. In this report we studied the role and collagen-binding properties of osteoclast integrins (alpha v, alpha 2, beta 1, and beta 3). Cell adhesion assays with rat osteoclasts and affinity chromatography/SDS-PAGE analysis with purified human osteoclast membranes demonstrated adhesion of osteoclasts to native type I collagen in a divalent cation and Arg-Gly-Asp (RGD)-dependent way via alpha 2 beta 1 integrin, whereas osteoclast adhesion to denatured collagen predominantly involved alpha v beta 3.

Different calcium sensitivity in osteoclasts on glass and on bone and maintenance of cytoskeletal structures on bone in the presence of high extracellular calcium.

The sensitivity of rat osteoclasts to increased extracellular calcium concentrations ([Ca2+]e) was investigated by single cell measurements of free cytosolic calcium concentrations ([Ca2+]i), by changes in microfilament organization of resorbing osteoclasts, and by in vitro bone resorption assays. Osteoclasts cultured on glass and on bone showed clear differences in their responses, as in 44% and 52% of osteoclasts on glass but in only 21% and 25% of osteoclasts on bone [Ca2+]i increased when [Ca2+]e was increased from 2 mM to 6 or 10 mM via perfusion, respectively. Bone resorption was inhibited without changes in the osteoclast numbers only by 10 mM [Ca2+]e in 2 day cultures.

Cytoskeletal changes in osteoclasts during the resorption cycle.

Osteoclasts are large, multinucleated cells which change their shape and polarity according to their resorptive activity. At least in vitro, nonresorbing osteoclasts move on the bone surface and do not show clear evidence of apical-basolateral polarity. When stimulated for resorption, osteoclasts undergo a rapid reorganization of the cytoskeleton and appear clearly polarized.

Isolation and characterization of highly enriched, prefusion mouse osteoclastic cells.

This study describes the isolation and characterization of highly enriched mammalian osteoclast precursors, released by the "disintegrin" echistatin, from an osteoclast formation culture. Incubation of a 6-day coculture of mouse bone marrow cells and mouse osteoblastic cells (MB1.8) with echistatin (30 nM), an RGD-containing snake venom, for 20 min yielded an 88-95% pure population of tartrate-resistant acid phosphatase-positive cells, 1.

Effects of recombinant human osteogenic protein-1 on the differentiation of osteoclast-like cells and bone resorption.

Recombinant human OP-1 stimulated the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs) significantly and in a dose-dependent manner in rat bone marrow cell culture. Newly formed MNCs either induced by hOP-1 alone or with 1,25(OH)2D3 were also positive for vitronectin receptor and carbonic anhydrase II. Moreover, OP-1 markedly increased the capacity of 1,25(OH)2D3 to induce osteoclast-like cell formation and bone resorption in bone marrow cultures.

Spatial organization of microfilaments and vitronectin receptor, alpha v beta 3, in osteoclasts. A study using confocal laser scanning microscopy.

The primary function of the osteoclast is that of the major cell mediating bone resorption. They are actively migrating cells but during resorption they polarize to form a specialized tight attachment structure, the sealing zone, adjacent to the mineralized bone matrix. The processes of adhesion to, and migration on, bone involves cell adhesion molecules, integrins, interacting with their ligands in bone.

Mitochondrial carbonic anhydrase in osteoclasts and two different epithelial acid-secreting cells.

Acid secreting cells are rich in mitochondria and contain high levels of cytoplasmic carbonic anhydrase II. We have studied the ultrastructural distribution of a mitochondrial isoenzyme, carbonic anhydrase V, in two different acid-secreting epithelial cells, gastric parietal cells and kidney intercalated cells as well as in osteoclasts, which are the main bone resorbing cells. The mitochondria differ in carbonic anhydrase V content in these three acid-producing cells: gastric parietal cell mitochondria show strong immunolabelling for this isoenzyme, osteoclast mitochondria faint labelling and kidney intercalated cell mitochondria no labelling.

Vitronectin receptor has a role in bone resorption but does not mediate tight sealing zone attachment of osteoclasts to the bone surface.

During bone resorption, osteoclasts form a tight attachment, the sealing zone, around resorption lacunae. Vitronectin receptor has previously been shown to be expressed in osteoclasts and it has been suggested that it mediates the tight attachment at the sealing zone. In this study we have shown that glycine-arginine-glycine-aspartic acid-serine pentapeptide inhibits bone resorption by isolated osteoclasts and drastically changes the morphology of the osteoclasts.

Inhibition of bone resorption by a monoclonal antibody that reacts with a 150 kD membrane protein in chicken osteoclasts.

Bone resorption is a multistep process that includes the maturation of osteoclast precursors, the special attachment of fully differentiated osteoclasts to mineralized bone surface, and the dissolution of inorganic mineral, as well as the breakdown of organic matrix. We have produced a large panel of monoclonal antibodies directed against chicken osteoclasts to obtain specific probes for studying the function of osteoclasts. One of our antibodies, K20, inhibited bone resorption of isolated osteoclasts almost completely.

Kinetics of the osteoclast cytoskeleton during the resorption cycle in vitro.

Resorption and migration phases alternate in the life of the osteoclast. We have previously described a specific microfilament structure at the attachment sites in resorbing osteoclasts. In the present study we have examined microfilaments and microtubules in both resorbing and migrating rat osteoclasts cultured on bone slices.

Calcitonin, prostaglandin E2, and dibutyryl cyclic adenosine 3',5'-monophosphate disperse the specific microfilament structure in resorbing osteoclasts.

Bone resorbing osteoclasts form a specific microfilament structure at the attachment area, in which vinculin and talin appear as a double-circle structure and F-actin fills the space between these circles. This distribution of microfilaments is associated with the resorption lacunae, and F-actin, vinculin, and talin zones correspond roughly to the edges of the lacunae. In the present work, we examined by immunofluorescence the effects of calcitonin (CT) and prostaglandin E2 (PGE2), inhibitors of osteoclastic activity, as well as dibutyryl cyclic AMP (Bt2cAMP) and cytochalasin B, on the microfilament organization in resorbing osteoclasts.