Heiko Knoop

Expression pattern of the deoxyribonuclease 1 gene: lessons from the Dnase1 knockout mouse.

The tissue distribution of deoxyribonuclease 1 (DNASE1, DNase I), a Ca2+ and Mg2+/Mn2+-dependent secretory endonuclease, has previously been investigated. However, most of these studies did not account for the existence of different members of the DNASE1 gene family, did not differentiate between endogenous DNASE1 protein synthesis and its extracellular occurrence or were not performed with methods allowing both a sensitive and a specific detection. Now we re-examined the DNASE1 gene expression pattern by taking advantage of the Dnase1 knockout mouse model. Direct comparison of samples derived from wild-type (Dnase1+/+) and knockout (Dnase1-/-) mice allowed an unambiguous detection of Dnase1 gene expression at the mRNA and protein level. For the detection of Dnase1 activity, we developed a highly sensitive nuclease zymogram method. We observed high Dnase1 gene expression in the parotid and submandibular gland as well as in the kidney and duodenum, intermediate expression in the ileum, mesenterial lymph nodes, liver, ventral prostate, epididymis, ovary and stomach, and low expression in the sublingual, preputial, coagulation and pituitary gland. We report for the first time the lachrymal and thyroid glands, the urinary bladder and the eye to be Dnase1-expressing organs as well. Since Dnase1 knockout mice with the 129xC57Bl/6 mixed genetic background have indicated the protection against an anti-DNA autoimmune response as a new physiological function of Dnase1, knowledge of the physiological sites of its synthesis might prove helpful to find new therapeutic strategies.

Frequent Detection of Latent Tuberculosis Infection among Aged Underground Hard Coal Miners in the Absence of Recent Tuberculosis Exposure

Background Miners are at particular risk for tuberculosis (TB) infection due to exposure to silica dust and silicosis. The objectives of the present observational cohort study were to determine the prevalence of latent TB infection (LTBI) among aged German underground hard coal miners with silicosis or chronic obstructive pulmonary disease (COPD) using two commercial interferon-gamma release assays (IGRAs) and to compare their performance with respect to predictors of test positivity. Methods Between October 2008 and June 2010, miners were consecutively recruited when routinely attending pneumoconiosis clinics for an expert opinion. Both IGRAs, the QuantiFERON®-TB Gold In-Tube (QFT) and the T-SPOT®.TB (T-SPOT), were performed at baseline. A standardized clinical interview was conducted at baseline and at follow-up. The cohort was prospectively followed regarding the development of active TB for at least two years after inclusion of the last study subject. Independent predictors of IGRA positivity were calculated using logistic regression. Results Among 118 subjects (mean age 75 years), none reported recent exposure to TB. Overall, the QFT and the T-SPOT yielded similarly high rates of positive results (QFT: 46.6%; 95% confidence interval 37.6–55.6%; T-SPOT: 61.0%; 95% confidence interval 52.2–69.8%). Positive results were independently predicted by age ≥80 years and foreign country of birth for both IGRAs. In addition, radiological evidence of prior healed TB increased the chance of a positive QFT result fivefold. While 28 subjects were lost to follow-up, no cases of active TB occurred among 90 subjects during an average follow-up of >2 years. Conclusions Considering the high prevalence of LTBI, the absence of recent TB exposure, and the currently low TB incidence in Germany, our study provides evidence for the persistence of specific interferon-gamma responses even decades after putative exposure. However, the clinical value of current IGRAs among our study population, although probably limited, remains uncertain.

The role of respiratory infections in chronic obstructive pulmonary disease

ZusammenfassungDie Morbiditäts- und Mortalitätsraten der chronisch-obstruktiven Lungenerkrankung (COPD) sind heute schon erheblich und werden in naher Zukunft noch weiter ansteigen. Somit gewinnt diese Erkrankung zunehmend an volkswirtschaftlicher Bedeutung. Die Kenntnisse der zugrundeliegenden Mechanismen erscheinen daher von besonderer Relevanz, vor allem weil bislang noch keine kurativen Therapieansätze vorhanden sind.Atemwegsinfektionen wurden in den letzten Jahren zunehmend als wesentliche Auslöser der Exazerbation der Erkrankung objektiviert. Es zeigt sich aber auch, dass ihnen eine wichtige Bedeutung bei der Pathogenese der Erkrankung zukommen könnte, was zu neuen therapeutischen Perspektiven führen würde.Ziel dieser Übersicht ist es daher, die Atemwegsentzündung bei der COPD zu beschreiben und die besondere Rolle von Atemwegsinfektionen darzustellen.AbstractMorbidity and mortality of chronic obstructive pulmonary disease (COPD) are considerable and still increasing. The disease is gaining increasing socioeconomic importance. The knowledge of underlying mechanisms is of special relevance because of the lack of a curative therapy.Respiratory infections have been identified as the most important triggers of acute exacerbations but recent data suggest that they might also play an important role in COPD pathogenesis. This knowledge might offer new therapeutic perspectives in the future.The aim of this review is, therefore, to describe the inflammatory processes involved and to specify the role of respiratory infections in this context.

Endothelin receptor-antagonists suppress lipopolysaccharide-induced cytokine release from alveolar macrophages of non-smokers, smokers and COPD subjects

Smoking-induced COPD is characterized by chronic airway inflammation, which becomes enhanced by bacterial infections resulting in accelerated disease progression called exacerbation. Alveolar macrophages (AM) release endothelin-1 (ET-1), IL-6, CCL-2 and MMP-9, all of which are linked to COPD pathogenesis and exacerbation. ET-1 signals via ETA- and ETB-receptors (ETAR, ETBR). This is blocked by endothelin receptor antagonists (ERAs), like bosentan, which targets both receptors, ETAR-selective ambrisentan and ETBR-specific BQ788. Therefore, ERAs could have anti-inflammatory potential, which might be useful in COPD and other inflammatory lung diseases. We hypothesized that ERAs suppress cytokine release from AM of smokers and COPD subjects induced by lipopolysaccharide (LPS), the most important immunogen of gram-negative bacteria. AM were isolated from the broncho-alveolar lavage (BAL) of n=29 subjects (11 non-smokers, 10 current smokers without COPD, 8 smokers with COPD), cultivated and stimulated with LPS in the presence or absence of ERAs. Cytokines were measured by ELISA. Endothelin receptor expression was investigated by RT-PCR and western blot. AM expressed ETAR and ETBR mRNA, but only ETBR protein was detected. LPS and ET-1 both induced IL-6, CCL-2 and MMP-9. LPS-induced IL-6 release was increased in COPD versus non-smokers and smokers. Bosentan, ambrisentan and BQ788 all partially reduced all cytokines without differences between cohorts. Specific ETBR inhibition was most effective. LPS induced ET-1, which was exclusively blocked by BQ788. In conclusion, LPS induces ET-1 release in AM, which in turn leads to CCL-2, IL-6 and MMP-9 expression rendering AM sensitive for ERAs. ERAs could have anti-inflammatory potential in smoking-induced COPD.

Die Rolle von Atemwegsinfektionen bei der chronisch-obstruktiven Lungenerkrankung

ZusammenfassungDie Morbiditäts- und Mortalitätsraten der chronisch-obstruktiven Lungenerkrankung (COPD) sind heute schon erheblich und werden in naher Zukunft noch weiter ansteigen. Somit gewinnt diese Erkrankung zunehmend an volkswirtschaftlicher Bedeutung. Die Kenntnisse der zugrundeliegenden Mechanismen erscheinen daher von besonderer Relevanz, vor allem weil bislang noch keine kurativen Therapieansätze vorhanden sind.Atemwegsinfektionen wurden in den letzten Jahren zunehmend als wesentliche Auslöser der Exazerbation der Erkrankung objektiviert. Es zeigt sich aber auch, dass ihnen eine wichtige Bedeutung bei der Pathogenese der Erkrankung zukommen könnte, was zu neuen therapeutischen Perspektiven führen würde.Ziel dieser Übersicht ist es daher, die Atemwegsentzündung bei der COPD zu beschreiben und die besondere Rolle von Atemwegsinfektionen darzustellen.AbstractMorbidity and mortality of chronic obstructive pulmonary disease (COPD) are considerable and still increasing. The disease is gaining increasing socioeconomic importance. The knowledge of underlying mechanisms is of special relevance because of the lack of a curative therapy.Respiratory infections have been identified as the most important triggers of acute exacerbations but recent data suggest that they might also play an important role in COPD pathogenesis. This knowledge might offer new therapeutic perspectives in the future.The aim of this review is, therefore, to describe the inflammatory processes involved and to specify the role of respiratory infections in this context.

Die Rolle von Atemwegsinfektionen bei der chronisch-obstruktiven Lungenerkrankung@@@The Role of Respiratory Infections in Chronic Obstructive Pulmonary Disease

ZusammenfassungDie Morbiditäts- und Mortalitätsraten der chronisch-obstruktiven Lungenerkrankung (COPD) sind heute schon erheblich und werden in naher Zukunft noch weiter ansteigen. Somit gewinnt diese Erkrankung zunehmend an volkswirtschaftlicher Bedeutung. Die Kenntnisse der zugrundeliegenden Mechanismen erscheinen daher von besonderer Relevanz, vor allem weil bislang noch keine kurativen Therapieansätze vorhanden sind.Atemwegsinfektionen wurden in den letzten Jahren zunehmend als wesentliche Auslöser der Exazerbation der Erkrankung objektiviert. Es zeigt sich aber auch, dass ihnen eine wichtige Bedeutung bei der Pathogenese der Erkrankung zukommen könnte, was zu neuen therapeutischen Perspektiven führen würde.Ziel dieser Übersicht ist es daher, die Atemwegsentzündung bei der COPD zu beschreiben und die besondere Rolle von Atemwegsinfektionen darzustellen.AbstractMorbidity and mortality of chronic obstructive pulmonary disease (COPD) are considerable and still increasing. The disease is gaining increasing socioeconomic importance. The knowledge of underlying mechanisms is of special relevance because of the lack of a curative therapy.Respiratory infections have been identified as the most important triggers of acute exacerbations but recent data suggest that they might also play an important role in COPD pathogenesis. This knowledge might offer new therapeutic perspectives in the future.The aim of this review is, therefore, to describe the inflammatory processes involved and to specify the role of respiratory infections in this context.