Biomedical subjects

Sonja Matthiesen

Publications and source records attributed to Sonja Matthiesen.

5 recordsLinked to original sources

PubMed2006

Muscarinic receptors mediate stimulation of human lung fibroblast proliferation.

Airway remodeling is a structural alteration associated with chronic inflammatory and obstructive airway diseases, wherein fibroblasts are crucially involved. The present study investigates whether lung fibroblast proliferation is influenced by muscarinic mechanisms. For this purpose, expression of muscarinic receptors in MRC-5 human lung fibroblasts was characterized by semiquantitative RT-PCR, and the effects of muscarinic agonists and antagonists on ((3)H)-thymidine incorporation as a measure of proliferative activity were studied under different culture conditions. MRC-5 fibroblasts express mRNA encoding different subtypes of muscarinic receptors (M(2) > M(3) > M(4), traces for M(5) and no M(1)). Expression of M(2) and M(3) receptors was confirmed at the protein level by immunoblot analysis. Under different culture conditions, carbachol (up to 10 microM) or oxotremorine (10 microM) stimulated ((3)H)-thymidine incorporation, with maximum increases between about 40 and 100%. The stimulatory effect of 10 microM carbachol was prevented by pretreatment with pertussis toxin and antagonized in a concentration-dependent manner by the muscarinic receptor antagonists tiotropium, AQ-RA 741, AF-DX 384, 4-diphenylacetoxy-N-methylpiperidine methoiodide, himbacine, p-fluorohexahydrosiladifenidol, and pirenzepine, with concentrations producing 50% inhibition of 14 pM, 24, 64, 127, 187, 452 nM, and 1.5 microM, respectively. Primary human lung fibroblasts were also found to express mRNA for muscarinic receptors (M(2) > M(1) > M(3), traces for M(4) and no M(5)), and showed a pertussis toxin-sensitive proliferative response to muscarinic receptor stimulation. In conclusion, proliferation of human lung fibroblasts can be stimulated by activation of muscarinic receptors with a pharmacologic profile correlating best to M(2) receptors.

Cell Line↗

PubMed2006

Control by cholinergic mechanisms.

In the respiratory tract acetylcholine is neurotransmitter in ganglia and postganglionic parasympathetic nerves, but in addition is paracrine mediator released from various non-neuronal cells. Almost every cell type present in the respiratory tract expresses nicotinic and muscarinic receptors and therefore appears to be a target for acetylcholine. The present review describes the mechanisms of synthesis and release of acetylcholine from neuronal and non-neuronal cells and the differential control mechanisms. The different cholinoceptors, multiple nicotinic and muscarinic receptors and their signalling are outlined and their involvement in the modulation of the function of various target cells, smooth muscles, nerves, surface epithelial, secretory cells, fibroblasts and inflammatory cells is discussed in detail.

Acetylcholine↗

PubMed2005

Increased arginase activity in cystic fibrosis airways.

RATIONALE: Airway nitric oxide concentrations are reduced in cystic fibrosis (CF). Arginases compete for L-arginine, the substrate of nitric oxide synthesis. OBJECTIVES: We hypothesized that increased arginase activity may be one factor contributing to nitric oxide deficiency in CF. MEASUREMENTS: We therefore studied sputum arginase activity, exhaled nitric oxide, and pulmonary function in patients with cystic fibrosis. RESULTS: Mean (+/- SEM) sputum arginase activity was significantly higher in patients admitted for pulmonary exacerbation compared with patients with stable disease (1.032 +/- 0.148 vs. 0.370 +/- 0.091 U/mg protein, p = 0.004). Fourteen days of intravenous antibiotic treatment resulted in significantly decreased sputum arginase activity in all patients (p = 0.0002). However, arginase activity was still significantly (p = 0.0001) higher in CF sputum after treatment for exacerbation compared with induced sputum from healthy control subjects (0.026 +/- 0.006 U/mg protein). Negative correlations were found for sputum arginase activity at admission with FEV1 (r = -0.41, p = 0.01), as well as changes in arginase activity with percent change in FEV1 during antibiotic therapy (r = -0.4, p < 0.01) in CF. Exhaled nitric oxide in CF was positively correlated to FEV1 (r = 0.34, p = 0.007), and in patients admitted for pulmonary exacerbation negatively correlated to sputum arginase activity (r = -0.45, p = 0.03). CONCLUSIONS: These data suggest that increased sputum arginase activity contributes to nitric oxide deficiency in CF lung disease and may be relevant in the pathogenesis of CF airway disease.

Adolescent↗

PubMed2005

A mouse model for cystic biliary dysgenesis in autosomal recessive polycystic kidney disease (ARPKD).

Autosomal recessive polycystic kidney disease (ARPKD) is an important cause of liver- and renal-related morbidity and mortality in childhood. Recently, PKHD1, the gene encoding the transmembrane protein polyductin, was shown to be mutated in ARPKD patients. We here describe the first mouse strain, generated by targeted mutation of Pkhd1. Due to exon skipping, Pkhd1ex40 mice express a modified Pkhd1 transcript and develop severe malformations of intrahepatic bile ducts. Cholangiocytes maintain a proliferative phenotype and continuously synthesize TGF-beta1. Subsequently, mesenchymal cells within the hepatic portal tracts continue to synthesize collagen, resulting in progressive portal fibrosis and portal hypertension. Fibrosis did not involve the hepatic lobules, and we did not observe any pathological changes in morphology or function of hepatocytes. Surprisingly and in contrast to human ARPKD individuals, Pkhd1ex40 mice develop morphologically and functionally normal kidneys. In conclusion,our data indicate that subsequent to formation of the embryonic ductal plate, dysgenesis of terminally differentiated bile ducts occurs in response to the Pkhd1ex40 mutation. The role of polyductin in liver and kidney may be functionally divergent, because protein domains essential for bile duct development do not affect nephrogenesis in our mouse model.

Animals↗

PubMed2002

Identification and characterization of Pkhd1, the mouse orthologue of the human ARPKD gene.

PKHD1, the gene mutated in human autosomal recessive polycystic kidney disease has recently been identified. Its translation products are predicted to belong to a superfamily of proteins involved in the regulation of cellular adhesion and repulsion. One notable aspect of the gene is its unusually complex pattern of splicing. This study shows that mouse Pkhd1 and its translation products have very similar properties to its human orthologue. Mouse Pkhd1 extends over approximately 500 kb of genomic DNA, includes a minimum of 68 nonoverlapping exons, and exhibits a complex pattern of splicing. The longest ORF encodes a protein of 4059aa predicted to have an N-terminal signal peptide, multiple IPTs and PbH1 repeats, a single transmembrane span (TM), and a short cytoplasmic C-terminus. Although the protein sequence is generally well conserved (approximately 73% average identity), the C-termini share only 55% identity. The pattern of Pkhd1 expression by in situ hybridization was also examined in developing and adult mouse tissues over a range of ages (E12.5 to 3 mo postnatal). High levels of expression were present in renal and biliary tubular structures at all time points examined. Prominent Pkhd1 signals were also found in a number of other organs and tissues. Tissue-specific differences in transcript expression were revealed through the use of single exon probes. These data show that key features of human PKHD1 are highly conserved in the mouse and suggest that the complicated pattern of splicing is likely to be functionally important.

Animals↗