Kristina Forsman-Semb

Positional identification of TNFSF4, encoding OX40 ligand, as a gene that influences atherosclerosis susceptibility

Ath1 is a quantitative trait locus on mouse chromosome 1 that renders C57BL/6 mice susceptible and C3H/He mice resistant to diet-induced atherosclerosis. The quantitative trait locus region encompasses 11 known genes, including Tnfsf4 (also called Ox40l or Cd134l), which encodes OX40 ligand. Here we report that mice with targeted mutations of Tnfsf4 had significantly (P ≤ 0.05) smaller atherosclerotic lesions than did control mice. In addition, mice overexpressing Tnfsf4 had significantly (P ≤ 0.05) larger atherosclerotic lesions than did control mice. In two independent human populations, the less common allele of SNP rs3850641 in TNFSF4 was significantly more frequent (P ≤ 0.05) in individuals with myocardial infarction than in controls. We therefore conclude that Tnfsf4 underlies Ath1 in mice and that polymorphisms in its human homolog TNFSF4 increase the risk of myocardial infarction in humans.

Regulatory cross‐talk between adhesin operons in Escherichia coli: inhibition of type 1 fimbriae expression by the PapB protein

Pathogenic Escherichia coli often carry determinants for several different adhesins. We show a direct communication between two adhesin gene clusters in uropathogenic E.coli: type 1 fimbriae (fim) and pyelonephritis‐associated pili (pap). A regulator of pap, PapB, is a key factor in this cross‐talk. FimB recombinase turns on type 1 fimbrial expression, and PapB inhibited phase transition by FimB in both off‐to‐on and on‐to‐off directions. On‐to‐off switching requiring FimE was increased by PapB. By analysis of FimB– and FimE–LacZ translational fusions it was concluded that the increase in on‐to‐off transition rates was via an increase in FimE expression. Inhibition of FimB‐promoted switching was via a different mechanism: PapB inhibited FimB‐promoted in vitro recombination, indicating that FimB activity was blocked at the fim switch. In vitro analyses showed that PapB bound to several DNA regions of the type 1 fimbrial operon, including the fim switch region. These data show that Pap expression turns off type 1 fimbriae expression in the same cell. Such cross‐talk between adhesin gene clusters may bring about appropriate expression at the single cell level.

Identification of a susceptibility locus for migraine with and without aura on 6p12.2-p21.1

Migraine is the most common type of chronic episodic headache. To find novel susceptibility genes for familial migraine with and without aura, a genomewide screen was performed in a large family from northern Sweden. Evidence of linkage was obtained on chromosome 6p12.2-p21.1, with a maximum two-point lod score of 5.41 for marker D6S452. The patients with migraine shared a common haplotype of 10 Mb between markers D6S1650 and D6S1960.

Quantitative Trait Loci Analysis for Plasma HDL-Cholesterol Concentrations and Atherosclerosis Susceptibility Between Inbred Mouse Strains C57BL/6J and 129S1/SvImJ

Objective—The C57BL/6 (B6) and 129 mouse inbred strains differ markedly in plasma HDL-cholesterol concentrations and atherosclerosis susceptibility after a high-fat diet consumption. To identify loci controlling these traits, we performed quantitative trait loci (QTL) analysis. Methods and Results—We fed a high-fat diet to 294 (B6x129S1/SvImJ)F2 females for 14 weeks, measured plasma HDL concentrations and size of aortic fatty-streak lesions, genotyped F2 females, and performed QTL analysis. HDL concentrations were affected by six loci:Hdlq14 and Hdlq15 on chromosome 1 (peaks cM 80 and cM 104, logarithm of odds [LOD] 5.3 and 9.7, respectively); Hdlq16 on chromosome 8 (cM 44, LOD 2.6); Hdlq17 on chromosome 9 (cM 24, LOD 2.9); Hdlq18 on chromosome 12 (cM 20, LOD 5.9); and Hdlq19 on chromosome 2 (cM 90), which interacted with Hdlq15. Atherosclerosis susceptibility was affected by five loci:Ath17 on chromosome 10 (cM 34, LOD 6.6); Ath18 on chromosome 12 (cM 16, LOD 3.7); Ath19 (chromosome 11, cM 60), which interacted with Ath18; and Ath20 (chromosome 10, cM 10), which interacted with Ath21 (chromosome 12, cM 50). Conclusions—We identified six loci for HDL and five loci for atherosclerosis susceptibility in a (B6x129S1/SvImJ)F2 intercross.

Total desmosines in plasma and urine correlate with lung function

The aim of the present study was to evaluate the relationship between the matrix degradation biomarkers, desmosine and isodesmosine (desmosines), and lung function. Plasma and creatinine-corrected urinary total desmosines (P- and U-desmosines, respectively), lung function and diffusing capacity of the lung for carbon monoxide (DL,CO) were measured in a cohort of subjects from the Swedish Twin Registry. Concentrations of U- and P-desmosines were measured in 349 and 318 subjects, respectively; approximately one-third of subjects had chronic obstructive pulmonary disease (COPD). Age, female sex, body mass index (BMI) and smoking were significantly associated with U-desmosines in a multiple linear regression analysis. In the overall population, after adjustments for age, sex, height, BMI and smoking, concentrations of U-desmosines were significantly correlated with all lung function measures, and P-desmosines with forced expiratory volume in 1 s and DL,CO (p<0.05). With the exception of residual volume versus P-desmosines, relationships between concentrations of desmosines and lung function measures were markedly stronger in subjects with COPD compared with those without COPD. These cross-sectional data showing associations between desmosines and several lung function variables suggest that desmosines, particularly U-desmosines, could be a useful biomarker of COPD status.

Overexpression of Prdx6 reduces H2O2 but does not prevent diet-induced atherosclerosis in the aortic root

The mammalian 1-Cys peroxiredoxin (Prdx6) is a unique member of the peroxiredoxin family of proteins capable of protecting cells from metal-catalyzed oxidative damage. We recently identified Prdx6 as a candidate for the quantitative trait locus Ath1, a gene responsible for a difference in diet-induced atherosclerosis susceptibility in mice. To investigate the role of Prdx6 in atherosclerosis, we generated transgenic mice that overexpress the Prdx6 allele from the Ath1-resistant 129/SvJ strain on an Ath1-susceptible C57BL/6J background. These mice expressed significantly elevated levels of Prdx6 mRNA and protein in multiple tissues including liver, aorta, and peritoneal macrophages, which accumulated significantly lower levels of hydrogen peroxide, revealing an enhanced antioxidant activity in these mice. However, overexpression of Prdx6 had no protective effect on LDL oxidation in vitro, and transgenic mice fed an atherogenic diet for 10 weeks did not possess an increased resistance to atherosclerosis nor did they maintain the high prediet plasma HDL levels consistent with the Ath1-resistant phenotype. In addition, the Prdx6 allele from the susceptible strain was shown to have a higher antioxidant activity than that of the resistant strains. These data suggest that the increased peroxidase activity attributable to Prdx6 overexpression in transgenic mice is not sufficient to protect mice from atherosclerosis, and that Prdx6 is not likely to be the gene underlying Ath1.

Efficacy, safety and effect on biomarkers of AZD9668 in cystic fibrosis

The aim of this study was to evaluate the safety and effect on clinical outcomes and biomarkers of inflammation and tissue damage of the neutrophil elastase inhibitor AZD9668 (60 mg twice daily orally for 4 weeks) in cystic fibrosis. This was a randomised, double-blind, placebo-controlled study. Primary outcome measures were sputum neutrophil count, lung function, 24-h sputum weight, BronkoTest® diary card data and health-related quality-of-life (revised cystic fibrosis quality-of-life questionnaire). Secondary end-points included sputum neutrophil elastase activity, inflammatory biomarkers in sputum and blood, urine and plasma desmosine (an elastin degradation marker), AZD9668 levels and safety parameters (adverse events, routine haematology, biochemistry, electrocardiogram and sputum bacteriology). 56 patients were randomised, of which 27 received AZD9668. There was no effect for AZD9668 on sputum neutrophil counts, neutrophil elastase activity, lung function or clinical outcomes, including quality of life. In the AZD9668 group, there was a trend towards reduction in sputum inflammatory biomarkers with statistically significant changes in interleukin-6, RANTES and urinary desmosine. The pattern of adverse events was similar between groups. Consistent reductions in sputum inflammatory biomarkers were seen in the AZD9668 group, and reduction in urinary desmosine suggests that AZD9668 impacts elastin cleavage by neutrophil elastase.

Genomic Organization of Human DLG4, the Gene Encoding Postsynaptic Density 95

Abstract : We have determined the exon‐intron organization and characterized the 5′‐flanking promoter region of DLG4. Encompassing ~30 kb, the DLG4 locus is composed of 22 exons that range in size from 28 to 1,218 nucleotides. All splice sites conform to the GT‐AG rule, except for the splice acceptor site of intron 5, which is TG instead of AG. Three different exons of DLG4 were found to be alternatively spliced in a subset of tissues. Two of these variants result in altered postsynaptic density 95 (PSD95) isoforms that dramatically truncate the protein. The third splicing variant represents an extension of exon 4 that encodes an additional 33‐amino acid segment. Analysis of the core promoter region for DLG4 suggests that the expression of this gene is controlled by a TATA‐less promoter using a single transcriptional start site embedded within a CpG island. DLG4 maps to a region on chromosome 17p13.1 known to contain a locus for autosomal dominant cone dystrophy 5. Scanning for mutations in the DLG4 coding region and splice sites was performed in 15 cone dystrophy patients, including probands from five families showing linkage to the DLG4 region. No disease‐causing mutations were identified in any patients, suggesting that DLG4 is not the causative gene for this genetic eye disorder.

Blood biomarkers and measures of pulmonary function-A study from the Swedish twin registry.

OBJECTIVE There is great need of biomarkers for research and clinical purposes in COPD. This study explored the relationships between ten putative plasma biomarkers of COPD and physiological measures of reduced lung function. METHODS FEV(1), FVC, residual volume/total lung capacity (RV/TLC) and CO diffusion capacity (D(L)CO) were assessed in 357 subjects from the Swedish Twin Registry. The lung function measures were studied in relation to plasma levels of desmosines, C-reactive protein (CRP), plasminogen inhibitor activator (PAI-1) concentration and activity, tissue inhibitor of metalloproteinase (TIMP-1), clara cell protein 16 (CC16), surfactant protein D (SPD), matrix metalloproteinase 9 (MMP-9), hepatocyte growth factor (HGF) and interleukin (IL)-8. RESULTS After adjustments for age, sex, height, BMI and smoking, FEV(1) was significantly associated with PAI-1 activity and desmosines. RV/TLC was significantly associated with CC16, PAI-1 concentration and PAI-1 activity, and D(L)CO was significantly associated with desmosines, TIMP-1 and CRP. When the multivariate analysis was restricted to subjects with COPD (i.e., FEV(1)/FVC < 0.70), CRP and desmosines were inversely associated with lung function. CONCLUSION Several biomarkers were associated with lung function in this cross-sectional study. Especially CRP and desmosines could be useful markers to assess disease severity in subjects with COPD.

Structural and functional studies of the fimbrial adhesin gene regulator PAPB from uropathogenic Escherichia coli

a) Purified PapB protein was shown to recognize a motif including a 9- bp repeat sequence containing T/A triplets at a conserved position. PapB binding was affected by distamycin, and the results were consistent with the possibility that the binding to DNA occurred through minor groove interaction. b) The DNA binding saturation results and visualization of DNA-PapB complex by AFM suggested that PapB can bind DNA in an oligomeric fashion. c) Mutations altering Arg61 or Cys65 caused deficiency in DNA binding, indicating that these residues are critical for PapB binding to DNA. Alanine substitutions at positions 35–36, 53–56, and 74–76 resulted in mutants that were impaired in oligomerization. d) The transcriptional efficiency of all the mutants was clearly reduced as compared with that of wild-type PapB, indicating that both DNA binding and oligomerization are required for PapB as a transcriptional regulator.