Interleukin secretion, proteoglycan and procollagen alpha(1)(I) gene expression in Crouzon fibroblasts treated with basic fibroblast growth factor

Unexpected artefacts and occult pathologies under CBCT

Purpose

To present the most frequent occult pathologies unexpectedly encountered via cone-beam computed tomography (CBCT), with particular reference to the diagnostic role of the dentist and that of the radiographer, with a view to clarifying where the diagnostic responsibility lies.

Material and methods

A narrative literature review on the most diffused occult pathologies under CBCT was conducted, with iconographical guide as an example for each category.

Results

The most frequent forms of unexpected pathologies encountered are: the presence of foreign bodies, airway anomaly, and the presence of radio-opacity or -transparency in the maxillofacial district.

Conclusions

The orthodontists must know that they are responsible to recognize these frequent, and potentially serious, pathologies of the head and neck. If the dentist feels unable to take on this responsibility, he or she should, however, be sure to have the scans read by a specialist radiologist.

Cleft palate only: current concepts

Cleft palate only (CPO) is one of the most common congenital malformations worldwide. The etiopathogenesis of CPO is not completely understood. Environmental factors, such as smoking, alcohol consumption, intake of drugs during pregnancy, advanced paternal age, have been demonstrated to be a risk of CPO, but conflicting results have also been published. Insufficient intake of folic acid during the pregnancy has been suggested to increase the risk for CPO. The demonstrated risk for siblings and the higher risk for monozygotic twins suggest a genetic etiopathogenesis for CPO. In some cases of CPO a prevalent mode of inheritance has been reported, but oligogenic models with reduced penetrance, and the risk related to environmental factors have also been proved. One of the first manifestations associated with CPO is difficulty with feeding. Aerophagia is a problem in these infants with CPO and requires more frequent burping and slower feeding. The inability to generate intraoral breath pressure due to nasal air emission in CPO children frequently manifests as articulation difficulties, particularly consonant weakness, and unintelligible speech. Hearing disorders are prevalent among individuals with CPO, as a result of chronic otitis media with effusion due to eustachian tube dysfunction. A multidisciplinary team is essential to manage the many aspects of CPO. In treating CPO, the reconstructive surgeon works in cooperation with otolaryngologists, dentists and orthodontists, speech pathologists, audiologists, geneticists, psychiatrists, maxillofacial surgeons, social workers, and prosthodontists. CPO can be considered a genetically complex disease, but new knowledge and new therapeutic approaches have greatly improved the quality of life of these children. Prenatal diagnosis is an important step in the treatment of this disease.

New insights in orofacial cleft: epidemiological and genetic studies on italian samples

Cleft of the lip and/or palate (CL±P) is the most common congenital craniofacial anomaly affecting around 1 in 700 live births worldwide. Clefts of the human face can be classified anatomically as cleft lip only (CL), cleft palate only (CP), cleft lip and palate (CLP) or a combined group of cleft lip with or without cleft palate (CL±P), based on differences in embryologic development. CL±P has a genetic base and several linkage and association analyses have been performed in order to obtain important information about the role of candidate genes in its onset; not less important are gene-environment interactions that play an increasing role in its aetiology. In CL±P, several loci have been seen associated with the malformation, and, in some cases, a specific gene mapping in a locus has also been identified as susceptibility factor. In CP, one gene has been found, but many more are probably involved. In this short review the genetic studies carried out on CL±P, and the interaction with environmental factors (alcohol, smoking, drugs) are discussed.

A synthetic peptide from transforming growth factor-beta1 type III receptor prevents myocardial fibrosis in spontaneously hypertensive rats

AIM

We investigated whether P144, a synthetic peptide from transforming growth factor-beta(1) (TGF-beta(1)) type III receptor betaglycan, exhibits cardiac antifibrotic properties.

METHODS AND RESULTS

The study was carried out in one group of 10-week-old normotensive Wistar-Kyoto rats treated with vehicle (V-WKY), one group of 10-week-old spontaneously hypertensive rats treated with vehicle (V-SHR), and one group of 10-week-old SHR treated with P144 (P144-SHR) for 12 weeks. Two more groups of 10-week-old untreated WKY and SHR were used to assess baseline values of the parameters tested. In addition, the effects of P144 on rat cardiac fibroblasts stimulated with TGF-beta(1) were also studied. Compared with V-WKY, V-SHR exhibited significant increases in the myocardial expression of phosphorylated Smad2, 38 and 42 kDa connective tissue growth factor (CTGF) isoforms, procollagen alpha1 (I) mRNA, and collagen type I protein, as well as in the expression of lysyl oxidase (LOX) mRNA and protein, collagen cross-linking and deposition. P144 administration was associated with significant reduction in all these parameters in P144-SHR. TGF-beta(1)-stimulated fibroblasts exhibited significant increases in phosphorylated Smad2, 38 and 42 kDa CTGF proteins, and procollagen alpha(1) (I) mRNA compared with control fibroblasts. No significant differences were found in these parameters between fibroblasts incubated with TGF-beta(1) and P144 and control fibroblasts.

CONCLUSION

These results show that P144 inhibits TGF-beta(1)-dependent signalling pathway and collagen type I synthesis in cardiac fibroblasts. These effects may be involved in the ability of this peptide to prevent myocardial fibrosis in SHR.

FGF2 effects in periosteal fibroblasts bearing the FGFR2 receptor Pro253 Arg mutation

AIM

A growing number of mutations mapped in the receptor gene for fibroblast growth factor have been implicated in several cranial development disorders including the Apert and Crouzon syndromes. The present paper investigated cellular mechanisms underlying Apert phenotype, by analyzing the effects of FGF2 in primary cultures of Apert periosteal fibroblasts carrying the FGFR2 Pro253Arg mutation.

RESULTS

FGF2 administration significantly decreased extracellular matrix production in mutant cells by stimulating degradative enzymatic activities. Gene expression analysis revealed that decorin and biglycan, two proteoglycans involved in collagen fibrillogenesis, were more expressed in mutant cells and down-regulated by FGF2. FGF2 receptor binding showed little differences in high affinity receptor counts between mutant and wild-type cells, while we showed for the first time that low affinity receptors are significantly fewer in mutant cells. Differences were found in Crouzon syndrome, where both high and low affinity receptor counts were up-regulated.

CONCLUSIONS

The different mutation and low affinity receptor regulation in mutant receptors support the hypothesis that the impact on the activity of the ligand-receptor complex could allow distinct modes of FGF2 activation in Apert and Crouzon syndromes, which interfere with the FGFR2 signalling cascade.

Basic fibroblast growth factor alleviates brain injury following global ischemia reperfusion in rabbits

The aim of this study was to explore the protective effect of basic fibroblast growth factor (bFGF) on brain injury following global ischemia reperfusion and its mechanisms. Brain injury following global ischemia was induced by four vessels occlusion and systemic hypotension. Twenty-four rabbits were randomized into three groups: group A, only dissection of vessels; group B, intravenous infusion of normal saline after reperfusion for 6 h; group C, 30 microg/kg bFGF injected intravenously at the onset of reperfusion, then infused with 10 microg/(kg.h) for 6 h. Serum neuron specific enolase (NSE), S-100B, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), interleukin-8 (IL-8) were measured before ischemia, 30 min after ischemia, 0.5, 1, 3, 6 h after reperfusion. Brain water content was determined and cerebral histopathological damages were compared. NSE and S-100B were increased 1 h after reperfusion and reached their peaks 6 h after reperfusion, but were much higher in group B than those in group C 3, 6 h after reperfusion. In groups B and C, TNF-alpha was increased after ischemia and IL-1 and IL-8 were increased significantly 0.5 h after reperfusion, then reached their peaks 6 h, 3 h, 6 h after reperfusion respectively. TNF-alpha and IL-8 at the time points of 1 h and 3 h and IL-1 at 3 h and 6 h in group C were correspondingly lower than those in group B. These indices in group A were nearly unchanged. There were less severe cerebral histopathological damages in group C compared with group B, but no difference in brain water content. It could be concluded that bFGF alleviates brain injury following global ischemia and reperfusion by down-regulating expression of inflammatory factors and inhibiting their activities.

Apert and Crouzon syndromes: clinical findings, genes and extracellular matrix

Apert and Crouzon syndromes are well known craniostenosis. In the last 10 years several studies were performed to provide a better understanding of the etiology and pathogenesis of these diseases. Both have an autosomal dominant mode of transmission, and a mutation in the gene encoding for the fibroblast growth factor receptor 2 (FGFR2) is the cause in most patients. However, the fact that the same mutation can produce a wide range of phenotypic expression makes the mechanism of anomalous development more complex. The extracellular matrix (ECM) is composed of proteins, glycosaminoglycans, and cytokines that are secreted in an autocrine and paracrine manner and are able to modify the ECM. Fibroblast growth factors are complexed with heparan sulfate, a component of the ECM, before binding the FGFR2. Data exist about different expressions of cytokines and ECM macromolecule in craniostenosis-derived fibroblasts and osteoblasts. Changes in ECM composition could explain the altered osteogenic process and account for pathologic variations in cranial development in addition to the FGFR2 mutations.

P253R fibroblast growth factor receptor-2 mutation induces RUNX2 transcript variants and calvarial osteoblast differentiation

Unregulated fibroblast growth factor 2 (FGF2) signaling caused by mutations in the fibroblast growth factor receptor (FGFR2) leads to human craniosynostosis such as the Apert syndrome. In an in vitro control model of calvarial osteoblasts from Apert patients carrying the FGFR2 P253R mutation, we studied the changes in cellular phenotype and evaluated the effects of FGF2. Compared with wild-type controls, osteocalcin mRNA was down-regulated in Apert osteoblasts, Runt-related transcription factor-2 (RUNX2) mRNA was differentially spliced, and FGF2 secretion was greater. Total protein synthesis, fibronectin and type I collagen secretion were up-regulated, while protease and glycosidase activities and matrix metalloproteinase-13 (MMP-13) transcription were decreased, suggesting an altered ECM turnover. Adding FGF2 increased protease and glycosidase activities and down-regulated fibronectin and type I collagen secretion in Apert osteoblasts. High affinity FGF2 receptors were up-regulated in Apert osteoblasts and analysis of signal transduction showed elevated levels of Grb2 tyrosine phosphorylation and the Grb2-p85 beta association, which FGF2 stimulation strongly reduced. All together these findings suggest increased constitutive receptor activity in Apert mutant osteoblasts and an autocrine loop involving the FGF2 pathway in modulation of Apert osteoblast behavior.

Cross-Talk Between Interleukin-6 and Transforming Growth Factor-β3Regulates Extracellular Matrix Production by Human Fibroblasts from Subjects with Non-Syndromic Cleft Lip and Palate

BACKGROUND

Transforming growth factor-beta (TGF-beta) interference with interleukin 6 (IL-6) activity and the role of the latter in early human embryonic development prompted us to examine the effects IL-6 on matrix synthesis and the effects of TGF-beta3 on IL-6 expression human cleft lip and palate (CLP) fibroblasts.

METHODS

Collagen and glycosaminoglycan (GAG) synthesis were determined by radiolabeled precursors and biglycan expression by Northern blotting before and after adding IL-6. The effects of TGF-beta3 on IL-6 production were assayed by evaluating IL-6 transcript by Northern blotting and IL-6 protein secretion by enzyme-linked immunosorbent assay.

RESULTS

The results showed that IL-6 elicited an inhibitory effect on collagen and GAG levels in CLP fibroblasts by lowering hyaluronan and dermatan sulfate secretion. IL-6 up-regulated biglycan expression, but less strongly than TGF-beta3. TGF-beta3 significantly down-regulated IL-6 transcript and secretion in CLP fibroblasts.

CONCLUSIONS

These data suggest the increase in matrix components that characterize the CLP fibroblast phenotype might be due to a concerted TGF-beta3-IL-6 action. We hypothesize changes in cross-talk between TGF-beta3 and IL-6 signal transduction pathways are involved in the induction of cleft palate.

Crouzon's syndrome: differential in vitro secretion of bFGF, TGFbeta I isoforms and extracellular matrix macromolecules in patients with FGFR2 gene mutation

In the Crouzon's syndrome the cranial morphogenic processes are altered due to the early fusion of cranial sutures. We analysed the phenotype of cultured fibroblasts from normal subjects and from Crouzon patients with a specific fibroblast growth factor receptor 2 mutation resulting in a Cys 342 Tyr substitution within the third immunoglobulin domain. Crouzon fibroblasts differed from normal fibroblasts in their extracellular matrix macromolecule accumulation. In Crouzon fibroblasts glycosaminoglycans and fibronectin were decreased and type I collagen increased. As transforming growth factors beta (TGF beta) and basic fibroblasts growth factor (bFGF) together regulate extracellular matrix deposition, we evaluated TGF beta(1), TGF beta(3) and bFGF production by Crouzon and normal fibroblasts. TGF beta(1), TGFb(3) and bFGF levels were lower while TGF beta(1) mRNA transcripts were higher in Crouzon cells. As the increased TGF beta(1) gene expression did not translate into a parallel increase of secreted TGF beta(1), control of TGF beta(1) secretion may be mainly post-transcriptional. Furthermore, adding bFGF increased TGF beta(1) and TGF beta(3) secretion, suggesting the drop may be due to the altered signal transduction of bFGF. These innovative data suggest the in vitro differences between normal and Crouzon fibroblasts may be due to an imbalance in TGF beta and bFGF levels which alters the microenvironment where morphogenesis takes place.

Basic fibroblast growth factor: effects on matrix remodeling, receptor expression, and transduction pathway in human periosteal fibroblasts with FGFR2 gene mutation

The Crouzon syndrome, which is associated with fibroblast growth factor receptor (FGFR2) mutations, is characterized by premature fusion of cranial sutures. We used an in vitro model of cultured periosteal fibroblasts from normal subjects and from Crouzon patients with FGFR2 mutation. We analyzed the matrix turnover rate and the effects of adding FGF2 by evaluating fibronectin synthesis and the activity of some proteolytic enzymes. To assess the role of some FGF signaling molecules involved in FGFR2 regulation, we studied Grb2 tyrosine phosphorylation and the phosphotyrosine proteins associated with Grb2. The iodinate FGF binding assay was performed to quantify FGFR expression. Compared with normal fibroblasts, fibronectin synthesis was decreased in Crouzon fibroblasts, and protease activities in cells and medium were enhanced, suggesting that excess fibronectin catabolism is present. Differences were more marked when FGF2 was added. Very few phosphoproteins were visible in anti-Grb2 immunoprecipitations from Crouzon fibroblasts, which showed a significant increase in the number of high-affinity and low-affinity FGF2 receptors. These results suggest that the abnormal genotype and the Crouzon cellular phenotype are related. To compensate the low levels of tyrosine phosphorylation, Crouzon cells might increase the numbers of FGFR2, thus increasing the cell surface binding sites for FGF2.