Die Surfactantkonversion als enzymatischer Prozeß : Ist das Surfactantprotein SP-B ein Substrat der Konvertase?

Das in der Alveole der Säugerlungen vorkommende Surfactantmaterial kann in sogenannte small und large surfactant aggregates aufgetrennt werden. Zu den large surfactant aggregates zählen Lamellarkörperchen und tubuläres Myelin, also die biophysikalisch hochaktiven Präkursoren des interfacialen Surfactantfilms. Unter den Prämissen einer akuten respiratorischen Insuffizienz ist wiederholt festgestellt worden, dass die Verteilung zwischen den large surfactant aggregates und small surfactant aggregates sehr zugunsten der small surfactant aggregates verschoben ist. Hieraus resultierend findet sich ein Übergewicht dieser, biophysikalisch weitgehend inaktiven, Abbauprodukte des Grenzflächenfilms. Vor diesem Hintergrund wurde in der vorliegenden Doktorarbeit der Fragestellung nachgegangen, wodurch die alveoläre Umwandlung der large in die small surfactant aggregates, ein als Surfactantkonversion bezeichneter Vorgang, vermittelt wird, und ob diese Surfactantkonversion ein enzymatisch getriggerter Prozess ist. Zur Beantwortung dieser Frage wurde als Ausgangsmaterial eine gepoolte bronchoalveoläre Lavage von gesunden Kaninchen, sowie ein rekonstituiertes Surfactantmaterial verwendet. Methodisch kamen weiterhin chromatographische, elektrophoretische, biophysikalische Verfahren, sowie Enzymaktivitäts-Assays zur Anwendung. Zunächst einmal konnte festgestellt werden, dass für die weitreichende Konversion von Surfactant in vitro in der Tat die Gegenwart einer Esterase notwendig ist. Weiterhin ergab sich im Rahmen der Rekonstitutionsversuche mit variablen Surfactant-Apoproteinen ebenfalls der Hinweis, dass vor allen Dingen der relative Gehalt an SP-B einen weitreichenden Einfluss auf den Konversionsgrad ausübt. Bei der Untersuchung der Herkunft der Esteraseaktivität in der BAL zeigte sich, dass im Überstand der resuspendierten Zellen der bronchoalveolären Lavage, wie auch im Zelllysat erhebliche Mengen an Esteraseaktivität nachweisbar waren. Weiterhin wurde festgestellt, dass unter den Bedingungen einer in vitro Konversion die Esteraseaktivität in den Subfraktionen alveolären Surfactans zeitabhängig abfiel. So war in den large surfactant aggregates 42 min nach Beginn der in vitro Konversion überhaupt keine Esteraseaktivität und nur noch etwa ein Viertel der Amidaseaktivität nachweisbar. Auf der Suche nach dem möglichen Substrat dieser Esterase wurde sowohl für die natürliche, wie auch für isoliert mit - an Sepharose gekoppelter - Esterase inkubiertem Surfactantprotein B der Nachweis erbracht, dass im Rahmen des Konversionsprozesses das dimere SP-B abgebaut und ein Spaltprodukt in einem Molekulargewichtsbereich von 11-14 kDa neu auftritt. Eine aminoterminale Sequenzierung dieses Spaltproduktes ergab zweifelsfrei den Nachweis eines Surfactantprotein B entstammenden Proteins und zwar des aminoterminalen Anteils des SP-B. Dieses Spaltprodukt konnte durch ein neu entwickeltes HPLC-Verfahren zur Auftrennung der hydrophoben Surfactantproteine aus der BAL weiter aufgereinigt werden. Zusammenfassend ergibt sich auf der Basis der hier vorliegenden Daten der Befund, dass die Umwandlung von large in small surfactant aggregates und der hiermit verbundene Verlust der Oberflächenaktivität nicht nur von der Größe der Oberflächenveränderung, sondern zudem von der Gegenwart einer enzymatischen Aktivität abhängig sind. Im Rahmen der hier durchgeführten Untersuchung konnte der Nachweis einer Esteraseaktivität sowohl in den Zellen der BAL, wie auch im zellfreien Überstand erbracht werden. Als mögliches Substrat dieser Aktivität konnte das Surfactantprotein B identifiziert werden, für welches das Auftreten eines 11-14 kDa großen Spaltproduktes einwandfrei belegt werden konnte. Aus der Kenntnis dieser Ergebnisse leiten sich mögliche neue Therapieoptionen für das Acute Respiratory Distress Syndrome, wie auch für den Ventilator Induced Lung Injury ab, bei denen Verschiebungen des alveolären Surfactantpools zugunsten der small surfactant aggregates wiederholt beschrieben worden sind.The alveolar surfactant pool can be separated into the \u27large surfactant aggregates\u27 (LSA) and the \u27small surfactant aggregates\u27 (SSA). The LSA, including lamellar bodies and tubular myelin, represent the biophysically highly active precursors of the interfacial surfactant film. Under cyclic area changes LSA are converted into the SSA (surfactant conversion). In contrast to LSA the SSA are clearly less surface active. Under clinical conditions of the acute respiratory distress syndrome, the balance of LSA to SSA is found to be switched in favour of SSA. Under these conditions, the alveolar surfactant pool predominantly consists of the largely inactive small surfactant aggregates, thus favouring impairment of gas exchange and lung function. Drawn against this background we aimed to elucidate the mechanisms of the conversion process. To answer this question pooled bronchoalveolar lavages of healthy rabbits and reconstituted surfactant preparations were subjected to repetitive surface area changes in vitro and extend of conversion was analysed. Besides chromatographic, electrophoretic and biophysical techniques, enzyme activity assays were applied for experimental investigations. It was found that an esterase activity is necessary for the induction of surfactant conversion under cyclic surface area changes. Experiments with various concentrations of the different surfactant proteins SP-A, SP-B or SP-C in reconstituted lipid mixtures revealed that only SP-B has a profound impact on the extent of in vitro conversion. Enzyme activity assays showed high esterase activity in complete cell suspensions of bronchoalveolar lavage and cell lysates. Under conditions of in vitro conversion, the esterase activity was found to decline in dependency of the incubation time, resulting in complete loss of esterase activity after 42 min of in vitro conversion. With emphasis on the potential role of surfactant proteins as substrates of esterase activity, we could show that in vitro conversion of BAL as well as incubation of isolated SP-B with sepharose linked esterase would result in a cleavage of dimeric SP-B and detection of a new protein band with a molecular range of 11-14 kilodalton. Amino terminal sequencing revealed that this protein truly represents a cleavage product of the amino terminal part of SP-B. Further purification of the cleavage product was performed by a new developed HPLC method for separation from other hydrophobic surfactant proteins and phospholipids. In summary the presented data support the conclusion that conversion of large surfactant aggregates to small surfactant aggregates not only depends on cyclic changes of the air-liquid interface, but also on the presence of an esterase activity. This esterase activity was detected in the cytosolic fraction of BAL cells, mostly alveolar macrophages. A SP-B cleavage product with a molecular range of 11-14 kilodalton was identified upon in vitro incubation of esterase with SP-B and after in vitro conversion of a rabbit BAL pool, suggesting that SP-B is a substrate of the alveolar esterase. These data may help to identify new molecular targets to treat acute respiratory distress syndrome and ventilator induced lung injury

Factors associated with severe dry eye in primary Sjögren´s syndrome diagnosed patients

Introduction Primary Sjögren?s syndrome (pSS) is an autoimmune disease, characterized by lymphocytic infiltration of exocrine glands and other organs, resulting in dry eye, dry mouth and extraglandular systemic findings. Objective To explore the association of severe or very severe dry eye with extraocular involvement in patients diagnosed with primary Sjögren?s syndrome. Methods SJOGRENSER registry is a multicenter cross-sectional study of pSS patients. For the construction of our main variable, severe/very severe dry eye, we used those variables that represented a degree 3?4 of severity according to the 2007 Dry Eye Workshop classification. First, bivariate logistic regression models were used to identify the effect of each independent variable on severe/very severe dry eye. Secondly, multivariate analysis using regression model was used to establish the independent effect of patient characteristics. Results Four hundred and thirty-seven patients were included in SJOGRENSER registry; 94% of the patients complained of dry eye and 16% developed corneal ulcer. Schirmer?s test was pathological in 92% of the patients; 378 patients presented severe/very severe dry eye. Inflammatory articular involvement was significantly more frequent in patients with severe/very severe dry eye than in those without severe/very severe dry eye (82.5 vs 69.5%, p = 0,028). Inflammatory joint involvement was associated with severe/very severe dry eye in the multivariate analysis, OR 2.079 (95% CI 1.096?3.941). Conclusion Severe or very severe dry eye is associated with the presence of inflammatory joint involvement in patients with pSS. These results suggest that a directed anamnesis including systemic comorbidities, such as the presence of inflammatory joint involvement or dry mouth in patients with dry eye, would be useful to suspect a pSS

Selection of reliable biomarkers from PCR array analyses using relative distance computational model: Methodology and proof-of-concept study

10.1371/journal.pone.0083954PLoS ONE812-POLN

Positional Cloning of a Type 2 Diabetes Quantitative Trait Locus; Tomosyn-2, a Negative Regulator of Insulin Secretion

We previously mapped a type 2 diabetes (T2D) locus on chromosome 16 (Chr 16) in an F2 intercross from the BTBR T (+) tf (BTBR) Lepob/ob and C57BL/6 (B6) Lepob/ob mouse strains. Introgression of BTBR Chr 16 into B6 mice resulted in a consomic mouse with reduced fasting plasma insulin and elevated glucose levels. We derived a panel of sub-congenic mice and narrowed the diabetes susceptibility locus to a 1.6 Mb region. Introgression of this 1.6 Mb fragment of the BTBR Chr 16 into lean B6 mice (B6.16BT36–38) replicated the phenotypes of the consomic mice. Pancreatic islets from the B6.16BT36–38 mice were defective in the second phase of the insulin secretion, suggesting that the 1.6 Mb region encodes a regulator of insulin secretion. Within this region, syntaxin-binding protein 5-like (Stxbp5l) or tomosyn-2 was the only gene with an expression difference and a non-synonymous coding single nucleotide polymorphism (SNP) between the B6 and BTBR alleles. Overexpression of the b-tomosyn-2 isoform in the pancreatic β-cell line, INS1 (832/13), resulted in an inhibition of insulin secretion in response to 3 mM 8-bromo cAMP at 7 mM glucose. In vitro binding experiments showed that tomosyn-2 binds recombinant syntaxin-1A and syntaxin-4, key proteins that are involved in insulin secretion via formation of the SNARE complex. The B6 form of tomosyn-2 is more susceptible to proteasomal degradation than the BTBR form, establishing a functional role for the coding SNP in tomosyn-2. We conclude that tomosyn-2 is the major gene responsible for the T2D Chr 16 quantitative trait locus (QTL) we mapped in our mouse cross. Our findings suggest that tomosyn-2 is a key negative regulator of insulin secretion

A Genome Wide Association Scan of Bovine Tuberculosis Susceptibility in Holstein-Friesian Dairy Cattle

peer-reviewedBackground: Bovine tuberculosis is a significant veterinary and financial problem in many parts of the world. Although many factors influence infection and progression of the disease, there is a host genetic component and dissection of this may enlighten on the wider biology of host response to tuberculosis. However, a binary phenotype of presence/absence of infection presents a noisy signal for genomewide association study. Methodology/Principal Findings: We calculated a composite phenotype of genetic merit for TB susceptibility based on disease incidence in daughters of elite sires used for artificial insemination in the Irish dairy herd. This robust measure was compared with 44,426 SNP genotypes in the most informative 307 subjects in a genome wide association analysis. Three SNPs in a 65 kb genomic region on BTA 22 were associated (i.e. p,1025, peaking at position 59588069, p = 4.0261026) with tuberculosis susceptibility. Conclusions/Significance: A genomic region on BTA 22 was suggestively associated with tuberculosis susceptibility; it contains the taurine transporter gene SLC6A6, or TauT, which is known to function in the immune system but has not previously been investigated for its role in tuberculosis infection

History, epidemiology and regional diversities of urolithiasis

Archeological findings give profound evidence that humans have suffered from kidney and bladder stones for centuries. Bladder stones were more prevalent during older ages, but kidney stones became more prevalent during the past 100 years, at least in the more developed countries. Also, treatment options and conservative measures, as well as ‘surgical’ interventions have also been known for a long time. Our current preventive measures are definitively comparable to those of our predecessors. Stone removal, first lithotomy for bladder stones, followed by transurethral methods, was definitively painful and had severe side effects. Then, as now, the incidence of urolithiasis in a given population was dependent on the geographic area, racial distribution, socio-economic status and dietary habits. Changes in the latter factors during the past decades have affected the incidence and also the site and chemical composition of calculi, with calcium oxalate stones being now the most prevalent. Major differences in frequency of other constituents, particularly uric acid and struvite, reflect eating habits and infection risk factors specific to certain populations. Extensive epidemiological observations have emphasized the importance of nutritional factors in the pathogenesis of urolithiasis, and specific dietary advice is, nowadays, often the most appropriate for prevention and treatment of urolithiasis

Genomic Sequence Analysis of Granulovirus Isolated from the Tobacco Cutworm, Spodoptera litura

Background: Spodoptera litura is a noctuid moth that is considered an agricultural pest. The larvae feed on a wide range of plants and have been recorded on plants from 40 plant families (mostly dicotyledons). It is a major pest of many crops. To better understand Spodoptera litura granulovirus (SpliGV), the nucleotide sequence of the SpliGV DNA genome was determined and analyzed. Methodology/Principal Findings: The genome of the SpliGV was completely sequenced. The nucleotide sequence of the SpliGV genome was 124,121 bp long with 61.2 % A+T content and contained 133 putative open reading frames (ORFs) of 150 or more nucleotides. The 133 putative ORFs covered 86.3 % of the genome. Among these, 31 ORFs were conserved in most completely sequenced baculovirus genomes, 38 were granulovirus (GV)-specific, and 64 were present in some nucleopolyhedroviruses (NPVs) and/or GVs. We proved that 9 of the ORFs were SpliGV specific. Conclusions/Significance: The genome of SpliGV is 124,121 bp in size. One hundred thirty-three ORFs that putatively encode proteins of 50 or more amino acid residues with minimal overlap were determined. No chitinase or cathepsin genes, which are involved in the liquefaction of the infected host, were found in the SpliGV genome, explaining why SpliGVinfected insects do not degrade in a typical manner. The DNA photolyase gene was first found in the genus Granulovirus. When phylogenic relationships were analyzed, the SpliGV was most closely related to Trichoplusia ni granulovirus (TnGV

Genetic causes of hypercalciuric nephrolithiasis

Renal stone disease (nephrolithiasis) affects 3–5% of the population and is often associated with hypercalciuria. Hypercalciuric nephrolithiasis is a familial disorder in over 35% of patients and may occur as a monogenic disorder that is more likely to manifest itself in childhood. Studies of these monogenic forms of hypercalciuric nephrolithiasis in humans, e.g. Bartter syndrome, Dent’s disease, autosomal dominant hypocalcemic hypercalciuria (ADHH), hypercalciuric nephrolithiasis with hypophosphatemia, and familial hypomagnesemia with hypercalciuria have helped to identify a number of transporters, channels and receptors that are involved in regulating the renal tubular reabsorption of calcium. Thus, Bartter syndrome, an autosomal disease, is caused by mutations of the bumetanide-sensitive Na–K–Cl (NKCC2) co-transporter, the renal outer-medullary potassium (ROMK) channel, the voltage-gated chloride channel, CLC-Kb, the CLC-Kb beta subunit, barttin, or the calcium-sensing receptor (CaSR). Dent’s disease, an X-linked disorder characterized by low molecular weight proteinuria, hypercalciuria and nephrolithiasis, is due to mutations of the chloride/proton antiporter 5, CLC-5; ADHH is associated with activating mutations of the CaSR, which is a G-protein-coupled receptor; hypophosphatemic hypercalciuric nephrolithiasis associated with rickets is due to mutations in the type 2c sodium–phosphate co-transporter (NPT2c); and familial hypomagnesemia with hypercalciuria is due to mutations of paracellin-1, which is a member of the claudin family of membrane proteins that form the intercellular tight junction barrier in a variety of epithelia. These studies have provided valuable insights into the renal tubular pathways that regulate calcium reabsorption and predispose to hypercalciuria and nephrolithiasis

Consumption of pasteurized human lysozyme transgenic goats’ milk alters serum metabolite profile in young pigs

Nutrition, bacterial composition of the gastrointestinal tract, and general health status can all influence the metabolic profile of an organism. We previously demonstrated that feeding pasteurized transgenic goats’ milk expressing human lysozyme (hLZ) can positively impact intestinal morphology and modulate intestinal microbiota composition in young pigs. The objective of this study was to further examine the effect of consuming hLZ-containing milk on young pigs by profiling serum metabolites. Pigs were placed into two groups and fed a diet of solid food and either control (non-transgenic) goats’ milk or milk from hLZ-transgenic goats for 6 weeks. Serum samples were collected at the end of the feeding period and global metabolite profiling was performed. For a total of 225 metabolites (160 known, 65 unknown) semi-quantitative data was obtained. Levels of 18 known and 4 unknown metabolites differed significantly between the two groups with the direction of change in 13 of the 18 known metabolites being almost entirely congruent with improved health status, particularly in terms of the gastrointestinal tract health and immune response, with the effects of the other five being neutral or unknown. These results further support our hypothesis that consumption of hLZ-containing milk is beneficial to health