ABSTRACT
OBJECTIVES: In patients with non-tuberculous mycobacterial pulmonary disease (NTM-PD), the response to treatment is evaluated based on microbiological, clinical, and radiological data. However, little is known about the dynamics of CT findings. The aim of this study was to evaluate CT changes in NTM-PD in order to define radiological criteria for treatment success. METHODS: Retrospective multicenter study (Hannover, Heidelberg, Gauting). Sixty patients with NTM-PD and at least two consecutive CT scans were included. Scoring for NTM-PD was performed by evaluating variables of bronchiectasis, mucus plugging, bronchiolitis, cavities, nodules, and consolidations on an ordinal scale from 0 to 3. Differences between baseline and follow-up were calculated, and patients with/without cultural conversion were compared using the Mann-Whitney U-test. For paired comparison of the two consecutive CT scans the Wilcoxon test was used. RESULTS: Comparing patients with and without culture conversion, there were significant differences in temporal changes of bronchiectasis (p < 0.001), cavities (p = 0.006), bronchiolitis (p < 0.001), consolidations (p = 0.004), and total score (p < 0.001). Nodules showed no significant differences between groups (p = 0.060). The Wilcoxon test showed significant differences between both CTs in patients with a microbiological cure for the total score (p < 0.001), cavities (p = 0.005), bronchiolitis (p < 0.001), and consolidations (p = 0.021) with a decrease after microbiological cure, whereas bronchiectasis (p = 0.102) and nodules (p = 0.18) stayed stable. In the case of persistently positive cultures, there was an increase in the total score (p = 0.010) which was attributable to progressive bronchiectasis (p < 0.001). CONCLUSION: Cavities, consolidations, and bronchiolitis are useful to assess treatment response, whereas bronchiectasis and nodules may remain stable despite successful treatment. CLINICAL RELEVANCE STATEMENT: Cavities, consolidations, and bronchiolitis can assess treatment response whereas bronchiectasis and nodules may remain stable despite successful treatment. In persistently positive cultures, bronchiectasis showed an increase over time indicating that NTM-PD is a progressive chronic disease. KEY POINTS: Little is known about CT changes in nontuberculous mycobacteria pulmonary disease (NTM-PD) and criteria to evaluate treatment response. In the case of culture conversion, cavities and bronchiolitis decreased whereas bronchiectasis and nodules remained stable. Cavities and bronchiolitis can evaluate treatment response in NTM, but bronchiectasis and nodules may persist despite successful treatment.
ABSTRACT
BACKGROUND: The aim of this retrospective study was to investigate the implementation of measures to prevent perioperative COVID-19 in thoracic surgery during the first wave of the COVID-19 pandemic 2020 allowing a continued surgical treatment of patients. METHODS: The implemented preventive measures in patient management of the thoracic surgery department of the Asklepios Lung Clinic Munich-Gauting, Germany were retrospectively analyzed. Postoperative COVID-19 incidence before and after implementation of preventive measures was investigated. Patients admitted for thoracic surgical procedures between March and May 2020 were included in the study. Patient characteristics were analyzed. For the early detection of putative postoperative COVID-19 symptoms, typical post-discharge symptomatology of thoracic surgery patients was compared to non-surgical patients hospitalized for COVID-19. RESULTS: Thirty-five surgical procedures and fifty-seven surgical procedures were performed before and after implementation of the preventive measures, respectively. Three patients undergoing thoracic surgery before implementation of preventive measures developed a COVID-19 pneumonia post-discharge. After implementation of preventive measures, no postoperative COVID-19 cases were identified. Fever, dyspnea, dry cough and diarrhea were significantly more prevalent in COVID-19 patients compared to normally recovering thoracic surgery patients, while anosmia, phlegm, low energy levels, body ache and nausea were similarly frequent in both groups. CONCLUSIONS: Based on the lessons learned during the first pandemic wave, we here provide a blueprint for successful easily implementable preventive measures minimizing SARS-CoV-2 transmission to thoracic surgery patients perioperatively. While symptoms of COVID-19 and the normal postoperative course of thoracic surgery patients substantially overlap, we found dyspnea, fever, cough, and diarrhea significantly more prevalent in COVID-19 patients than in normally recovering thoracic surgery patients. These symptoms should trigger further diagnostic testing for postoperative COVID-19 in thoracic surgery patients.
Subject(s)
COVID-19 , Thoracic Surgery , Thoracic Surgical Procedures , Aftercare , Humans , Pandemics , Patient Discharge , Retrospective Studies , SARS-CoV-2 , Thoracic Surgical Procedures/adverse effectsABSTRACT
EvA (Emphysema versus Airway disease) is a multicentre project to study mechanisms and identify biomarkers of emphysema and airway disease in chronic obstructive pulmonary disease (COPD). The objective of this study was to delineate objectively imaging-based emphysema-dominant and airway disease-dominant phenotypes using quantitative computed tomography (QCT) indices, standardised with a novel phantom-based approach.441 subjects with COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 1-3) were assessed in terms of clinical and physiological measurements, laboratory testing and standardised QCT indices of emphysema and airway wall geometry.QCT indices were influenced by scanner non-conformity, but standardisation significantly reduced variability (p<0.001) and led to more robust phenotypes. Four imaging-derived phenotypes were identified, reflecting "emphysema-dominant", "airway disease-dominant", "mixed" disease and "mild" disease. The emphysema-dominant group had significantly higher lung volumes, lower gas transfer coefficient, lower oxygen (PO2 ) and carbon dioxide (PCO2 ) tensions, higher haemoglobin and higher blood leukocyte numbers than the airway disease-dominant group.The utility of QCT for phenotyping in the setting of an international multicentre study is improved by standardisation. QCT indices of emphysema and airway disease can delineate within a population of patients with COPD, phenotypic groups that have typical clinical features known to be associated with emphysema-dominant and airway-dominant disease.
Subject(s)
Phenotype , Pulmonary Disease, Chronic Obstructive/diagnostic imaging , Pulmonary Disease, Chronic Obstructive/physiopathology , Pulmonary Emphysema/diagnostic imaging , Tomography, X-Ray Computed/standards , Adult , Aged , Europe , Female , Forced Expiratory Volume , Humans , Male , Middle Aged , Respiratory System/physiopathology , SpirometryABSTRACT
Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is a chronic inflammatory lung disease caused by infection with non-tuberculous mycobacteria (NTM). International guidelines provide evidence-based recommendations on appropriate diagnosis and treatment strategies, but there is a need for sharing day-to-day best practice between treatment centers to optimize patient care. This is particularly valuable for rare diseases like NTM-PD. In this cross-sectional analysis of NTM-PD management in Germany, medical and administrative staff from seven treatment centers were interviewed to identify best practice in the diagnosis, treatment, and ongoing management of patients with NTM-PD, including related hospital infrastructure and administration processes. A prioritization led to a collection of best practices for the management of patients with NTM-PD in Germany, which is presented here. Selected current best practices included performance of regular sputum tests for diagnosis, use of medical reports, and regular follow-up visits as well as increased interaction between physicians across different specialties. Future best practices that may be implemented to overcome current barriers comprised disease awareness activities, patient empowerment, and new approaches to enhance physician interaction. Challenges related to their implementation are also discussed and will help to raise disease awareness. The presented best practices may guide and optimize patient management in other centers.
ABSTRACT
Tuberculosis (TB) is one of the leading causes of death by an infectious disease. It remains a major health burden worldwide, in part due to misdiagnosis. Therefore, improved diagnostic tests allowing the faster and more reliable diagnosis of patients with active TB are urgently needed. This prospective study examined the performance of the new molecular whole-blood test T-Track® TB, which relies on the combined evaluation of IFNG and CXCL10 mRNA levels, and compared it to that of the QuantiFERON®-TB Gold Plus (QFT-Plus) enzyme-linked immunosorbent assay (ELISA). Diagnostic accuracy and agreement analyses were conducted on the whole blood of 181 active TB patients and 163 non-TB controls. T-Track® TB presented sensitivity of 94.9% and specificity of 93.8% for the detection of active TB vs. non-TB controls. In comparison, the QFT-Plus ELISA showed sensitivity of 84.3%. The sensitivity of T-Track® TB was significantly higher (p < 0.001) than that of QFT-Plus. The overall agreement of T-Track® TB with QFT-Plus to diagnose active TB was 87.9%. Out of 21 samples with discordant results, 19 were correctly classified by T-Track® TB while misclassified by QFT-Plus (T-Track® TB-positive/QFT-Plus-negative), and two samples were misclassified by T-Track® TB while correctly classified by QFT-Plus (T-Track® TB-negative/QFT-Plus-positive). Our results demonstrate the excellent performance of the T-Track® TB molecular assay and its suitability to accurately detect TB infection and discriminate active TB patients from non-infected controls.
ABSTRACT
Numbers of non-tuberculous mycobacteria (NTM) pulmonary diseases (PD) have been repeatedly reported as increasing over the last decades, particularly in Europe. Sound epidemiological data are however missing for most European regions. This study calculated prevalence and incidence of NTM recovered from patients' lungs in Germany, the largest Central European country, over a five-year period. It furthermore determined regional particularities of NTM species and results from susceptibility testing. 22 German NTM laboratories provided their mycobacteriological diagnostic data of 11,430 NTM isolates recovered from 5998 pulmonary patients representing 30% of all notified NTM-PD cases of Germany from 2016 to 2020. NTM incidence and prevalence were calculated for every study year. The presented epidemiological indicators are particularly reliant as TB surveillance data were used as a reference and TB notification reaches almost 100% in Germany. Laboratory incidence and prevalence of NTM recovered from respiratory samples ranged from 4.5-4.9 and from 5.3-5.8/100,000 for the population of Germany, respectively, and did not change over the five-year study period. Prevalence and incidence were stable also when stratifying for facultative pathogenic NTM, M. avium/intracellulare complex (MAIC), and M. abscessus/chelonae complex (MABSC). The proportion of NTM with drug susceptibility testing (DST) increased from 27.3% (2016) to 43.8% (2020). The unchanging laboratory NTM prevalence/incidence in Germany represents a "ceiling" of possible NTM-PD notification when diagnostic strategies do not change in the coming years. A notable increase in NTM-DST may indicate better notification of NTM-PD and/or awareness of new clinical guidelines but still remains below clinical needs.
Subject(s)
Lung Diseases , Mycobacterium tuberculosis , Humans , Nontuberculous Mycobacteria , Prevalence , Incidence , Laboratories , Microbial Sensitivity Tests , Lung Diseases/microbiologyABSTRACT
BACKGROUND: High-flow nasal cannula (HFNC) therapy is a helpful tool in the treatment of hypoxaemic respiratory failure. However, the clinical parameters predicting the effectiveness of HFNC in coronavirus-19 disease (COVID-19) patients remain unclear. METHODS: Sixteen COVID-19 patients undergoing HFNC in the Asklepios Lung Clinic Munich-Gauting, Germany between 16 March and 3 June 2020 were retrospectively included into the study. Seven patients successfully recovered after HFNC (Group 1), while 9 patients required intubation upon HFNC failure (Group 2). Relevant predictors for an effective HFNC therapy were analysed on day 0 and 4 after HFNC initiation via receiver operating characteristics. RESULTS: The groups did not differ significantly in terms of age, sex, body mass index, and comorbidities. Five patients died in Group 2 upon disease progression and HFNC failure. Group 1 required a lower oxygen supplementation (FiO2 0.46 [0.31-0.54] vs. 0.72 [0.54-0.76], P = 0.022) and displayed a higher PaO2/FiO2 ratio (115 [111-201] vs. 93.3 [67.2-145], P = 0.042) on day 0. In Group 2, fever persisted on day 4 (38.5 [38.0-39.4]°C vs. 36.5 [31.1-37.1]°C, P = 0.010). Serum C-reactive protein (CRP) levels > 108 mg L-1 (day 0) and persistent oxygen saturation < 89% and PaO2/FiO2 ratio < 91 (day 4) were identified as significant predictors for HFNC failure (area under curve 0.929, 0.933, and 0.893). CONCLUSIONS: Elevated oxygen saturation, decreased FiO2 and reduced serum CRP on day 4 significantly predict HFNC effectiveness in COVID-19 patients. Based on these parameters, larger prospective studies are necessary to further investigate the effectiveness of HFNC in the treatment of COVID-19-associated hypoxaemic respiratory failure.
Subject(s)
COVID-19 , COVID-19/therapy , Humans , Oxygen , Oxygen Inhalation Therapy , Prospective Studies , Retrospective StudiesABSTRACT
INTRODUCTION: Infectious complications represent a major cause of morbidity and mortality in hairy cell leukemia (HCL) patients. Due to the immunosuppressive nature of the disease, these patients are frequently affected by opportunistic infections and rare pathogens. Furthermore, cytotoxic chemotherapy might lead to poor or even fatal outcomes in the setting of an active infection. CASE PRESENTATION: We report the case of a 62-year-old HCL patient who presented with recurrent fever episodes, pancytopenia, and mediastinal lymphadenopathy. A treatment decision against purine analogs and for rituximab mono was made as lymph node tissue revealed disseminated Mycobacterium kansasii infection. Together with specific antimycobacterial treatment, rituximab mono led to complete hematologic remission after 6 months without aggravating the accompanying infection. CONCLUSION: Here, we demonstrate successful treatment of HCL with rituximab in a patient with concomitant disseminated M. kansasii infection.
Subject(s)
Leukemia, Hairy Cell , Mycobacterium Infections, Nontuberculous , Opportunistic Infections , Rituximab/therapeutic use , Humans , Leukemia, Hairy Cell/complications , Leukemia, Hairy Cell/drug therapy , Middle Aged , Mycobacterium Infections, Nontuberculous/diagnosis , Mycobacterium Infections, Nontuberculous/drug therapy , Mycobacterium kansasii , Opportunistic Infections/diagnosis , Opportunistic Infections/drug therapyABSTRACT
PURPOSE: This study aimed to identify predictive (bio-)markers for COVID-19 severity derived from automated quantitative thin slice low dose volumetric CT analysis, clinical chemistry and lung function testing. METHODS: Seventy-four COVID-19 patients admitted between March 16th and June 3rd 2020 to the Asklepios Lung Clinic Munich-Gauting, Germany, were included in the study. Patients were categorized in a non-severe group including patients hospitalized on general wards only and in a severe group including patients requiring intensive care treatment. Fully automated quantification of CT scans was performed via IMBIO CT Lung Texture analysis™ software. Predictive biomarkers were assessed with receiver-operator-curve and likelihood analysis. RESULTS: Fifty-five patients (44% female) presented with non-severe COVID-19 and 19 patients (32% female) with severe disease. Five fatalities were reported in the severe group. Accurate automated CT analysis was possible with 61 CTs (82%). Disease severity was linked to lower residual normal lung (72.5% vs 87%, p = 0.003), increased ground glass opacities (GGO) (8% vs 5%, p = 0.031) and increased reticular pattern (8% vs 2%, p = 0.025). Disease severity was associated with advanced age (76 vs 59 years, p = 0.001) and elevated serum C-reactive protein (CRP, 92.2 vs 36.3 mg/L, p < 0.001), lactate dehydrogenase (LDH, 485 vs 268 IU/L, p < 0.001) and oxygen supplementation (p < 0.001) upon admission. Predictive risk factors for the development of severe COVID-19 were oxygen supplementation, LDH >313 IU/L, CRP >71 mg/L, <70% normal lung texture, >12.5% GGO and >4.5% reticular pattern. CONCLUSION: Automated low dose CT analysis upon admission might be a useful tool to predict COVID-19 severity in patients.
Subject(s)
COVID-19 , Cone-Beam Computed Tomography , Female , Humans , Lung/diagnostic imaging , Male , Middle Aged , Retrospective Studies , SARS-CoV-2 , Severity of Illness Index , Tomography, X-Ray ComputedABSTRACT
Chronic obstructive pulmonary disease (COPD) is a destructive inflammatory disease and the genes expressed within the lung are crucial to its pathophysiology. We have determined the RNAseq transcriptome of bronchial brush cells from 312 stringently defined ex-smoker patients. Compared to healthy controls there were for males 40 differentially expressed genes (DEGs) and 73 DEGs for females with only 26 genes shared. The gene ontology (GO) term "response to bacterium" was shared, with several different DEGs contributing in males and females. Strongly upregulated genes TCN1 and CYP1B1 were unique to males and females, respectively. For male emphysema (E)-dominant and airway disease (A)-dominant COPD (defined by computed tomography) the term "response to stress" was found for both sub-phenotypes, but this included distinct up-regulated genes for the E-sub-phenotype (neutrophil-related CSF3R, CXCL1, MNDA) and for the A-sub-phenotype (macrophage-related KLF4, F3, CD36). In E-dominant disease, a cluster of mitochondria-encoded (MT) genes forms a signature, able to identify patients with emphysema features in a confirmation cohort. The MT-CO2 gene is upregulated transcriptionally in bronchial epithelial cells with the copy number essentially unchanged. Both MT-CO2 and the neutrophil chemoattractant CXCL1 are induced by reactive oxygen in bronchial epithelial cells. Of the female DEGs unique for E- and A-dominant COPD, 88% were detected in females only. In E-dominant disease we found a pronounced expression of mast cell-associated DEGs TPSB2, TPSAB1 and CPA3. The differential genes discovered in this study point towards involvement of different types of leukocytes in the E- and A-dominant COPD sub-phenotypes in males and females.
Subject(s)
Disease Susceptibility , Gene Expression , Leukocytes/metabolism , Mitochondria/genetics , Pulmonary Disease, Chronic Obstructive/etiology , Pulmonary Disease, Chronic Obstructive/metabolism , Respiratory Mucosa/metabolism , Biomarkers , Computational Biology/methods , Female , Gene Expression Profiling , Humans , Kruppel-Like Factor 4 , Leukocytes/immunology , Leukocytes/pathology , Male , Mitochondria/metabolism , Pulmonary Disease, Chronic Obstructive/pathology , Respiratory Mucosa/immunology , Respiratory Mucosa/pathology , Sex Factors , TranscriptomeABSTRACT
BD MAX MDR-TB assay is a new molecular platform for the detection of Mycobacterium tuberculosis complex (MTBC) in clinical specimens and simultaneous detection of resistance toward isoniazid and rifampicin. This study assessed the assay's diagnostic accuracy by using pre-characterized MTBC culture-negative (n = 257), smear-negative/MTBC culture-positive (n = 93), and smear-positive/MTBC culture-positive (n = 153) respiratory specimens. Compared with culture, the overall sensitivity and specificity of BD MAX MDR-TB were 86.6% and 100%, respectively; sensitivities for smear-positive and smear-negative samples were 100% and 64.5%. Sensitivity and specificity for isoniazid and rifampicin resistance were 58.3% (biased low due to sample collection strategy in low prevalence setting), 99.3%, 100%, and 98.2%, compared with phenotypic drug resistance testing and 100%, 99.4%, 100%, and 99.4%, compared with GenoType MTBDRplus. In conclusion, BD MAX MDR-TB is an accurate assay for the diagnostic detection of MTBC in respiratory samples and its resistance toward the most important anti-TB drugs isoniazid and rifampicin. Due to its medium to high throughput, good validity, and ease of use, the assay will be of great benefit for medium-sized to large TB diagnostic centers.
Subject(s)
Molecular Diagnostic Techniques/methods , Mycobacterium tuberculosis/genetics , Tuberculosis, Multidrug-Resistant/genetics , Tuberculosis, Multidrug-Resistant/microbiology , Genetic Markers , Humans , Isoniazid/pharmacology , Isoniazid/therapeutic use , Mycobacterium tuberculosis/drug effects , Reference Standards , Rifampin/pharmacology , Rifampin/therapeutic use , Tuberculosis, Multidrug-Resistant/drug therapyABSTRACT
The novel coronavirus disease 2019 is a highly contagious viral infection caused by the severe acute respiratory syndrome coronavirus 2 virus. Its rapid spread and severe clinical presentation influence patient management in all specialties including thoracic surgery. We report 3 cases of coronavirus disease 2019 occurring in patients shortly after thoracotomy and thoracoscopy procedures, illustrating the imminent threat of severe acute respiratory syndrome coronavirus 2 infection for thoracic surgery patients.
Subject(s)
Betacoronavirus , Coronavirus Infections/diagnosis , Cross Infection/diagnosis , Lung Neoplasms/surgery , Pneumonectomy/adverse effects , Pneumonia, Viral/diagnosis , Postoperative Complications/diagnosis , Adenocarcinoma/pathology , Adenocarcinoma/surgery , Aged , COVID-19 , Carcinoma, Squamous Cell/pathology , Carcinoma, Squamous Cell/surgery , Coronavirus Infections/etiology , Coronavirus Infections/therapy , Cross Infection/etiology , Cross Infection/therapy , Female , Humans , Lung Neoplasms/pathology , Male , Middle Aged , Pandemics , Pneumonia, Viral/etiology , Pneumonia, Viral/therapy , Postoperative Complications/etiology , Postoperative Complications/therapy , SARS-CoV-2 , Thoracoscopy/adverse effects , Thoracotomy/adverse effectsABSTRACT
Chronic obstructive pulmonary disease (COPD) is induced by cigarette smoking and characterized by inflammation of airway tissue. Since smokers with COPD have a higher risk of developing lung cancer than those without, we hypothesized that they carry more mutations in affected tissue. We called somatic mutations in airway brush samples from medium-coverage whole genome sequencing data from healthy never and ex-smokers (n = 8), as well as from ex-smokers with variable degrees of COPD (n = 4). Owing to the limited concordance of resulting calls between the applied tools we built a consensus, a strategy that was validated with high accuracy for cancer data. However, consensus calls showed little promise of representing true positives due to low mappability of corresponding sequence reads and high overlap with positions harbouring known genetic polymorphisms. A targeted re-sequencing approach suggested that only few mutations would survive stringent verification testing and that our data did not allow the inference of any difference in the mutational load of bronchial brush samples between former smoking COPD cases and controls. High polyclonality in airway brush samples renders medium-depth sequencing insufficient to provide the resolution to detect somatic mutations. Deep sequencing data of airway biopsies are needed to tackle the question.
Subject(s)
Biomarkers , Genetic Association Studies , Genetic Predisposition to Disease , Lung/metabolism , Lung/pathology , Mutation , Pulmonary Disease, Chronic Obstructive/diagnosis , Pulmonary Disease, Chronic Obstructive/etiology , Aged , Biopsy , Cigarette Smoking/adverse effects , Computational Biology , DNA Mutational Analysis , Female , Humans , Male , Middle Aged , Reproducibility of Results , Respiratory Function Tests , Risk Factors , Severity of Illness Index , Whole Genome SequencingABSTRACT
BACKGROUND: Changes in microbial community composition in the lung of patients suffering from moderate to severe COPD have been well documented. However, knowledge about specific microbiome structures in the human lung associated with CT defined abnormalities is limited. METHODS: Bacterial community composition derived from brush samples from lungs of 16 patients suffering from different CT defined subtypes of COPD and 9 healthy subjects was analyzed using a cultivation independent barcoding approach applying 454-pyrosequencing of 16S rRNA gene fragment amplicons. RESULTS: We could show that bacterial community composition in patients with changes in CT (either airway or emphysema type changes, designated as severe subtypes) was different from community composition in lungs of patients without visible changes in CT as well as from healthy subjects (designated as mild COPD subtype and control group) (PC1, Padj = 0.002). Higher abundance of Prevotella in samples from patients with mild COPD subtype and from controls and of Streptococcus in the severe subtype cases mainly contributed to the separation of bacterial communities of subjects. No significant effects of treatment with inhaled glucocorticoids on bacterial community composition were detected within COPD cases with and without abnormalities in CT in PCoA. Co-occurrence analysis suggests the presence of networks of co-occurring bacteria. Four communities of positively correlated bacteria were revealed. The microbial communities can clearly be distinguished by their associations with the CT defined disease phenotype. CONCLUSION: Our findings indicate that CT detectable structural changes in the lung of COPD patients, which we termed severe subtypes, are associated with alterations in bacterial communities, which may induce further changes in the interaction between microbes and host cells. This might result in a changed interplay with the host immune system.
Subject(s)
Bacteria/classification , Lung/microbiology , Pulmonary Disease, Chronic Obstructive/diagnostic imaging , Sequence Analysis, DNA/methods , Tomography, X-Ray Computed/methods , Aged , Bacteria/genetics , Bacteria/isolation & purification , DNA Barcoding, Taxonomic/methods , DNA, Bacterial/genetics , DNA, Ribosomal/genetics , Female , Humans , Lung/diagnostic imaging , Male , Microbiota , Middle Aged , Prevotella/classification , Prevotella/genetics , Prevotella/isolation & purification , Pulmonary Disease, Chronic Obstructive/complications , RNA, Ribosomal, 16S/genetics , Streptococcus/classification , Streptococcus/genetics , Streptococcus/isolation & purificationABSTRACT
The transcription factor PU.1 plays a pivotal role in normal myeloid differentiation. PU.1(-/-) mice exhibit a complete block in myeloid differentiation. Heterozygous PU.1 mutations were reported in some patients with acute myeloid leukemia (AML), but not in AML with translocation t(8;21), which gives rise to the fusion gene AML1-ETO. Here we report a negative functional impact of AML1-ETO on the transcriptional activity of PU.1. AML1-ETO physically binds to PU.1 in t(8;21)(+) Kasumi-1 cells. AML1-ETO binds to the beta(3)beta(4) region in the DNA-binding domain of PU.1 and displaces the coactivator c-Jun from PU.1, thus down-regulating the transcriptional activity of PU.1. This physical interaction of AML1-ETO and PU.1 did not abolish the DNA-binding capacity of PU.1. AML1-ETO down-regulates the transactivation capacity of PU.1 in myeloid U937 cells, and the expression levels of PU.1 target genes in AML French-American-British (FAB) subtype M2 patients with t(8;21) were lower than in patients without t(8;21). Conditional expression of AML1-ETO causes proliferation in mouse bone marrow cells and inhibits antiproliferative function of PU.1. Overexpression of PU.1, however, differentiates AML1-ETO-expressing Kasumi-1 cells to the monocytic lineage. Thus, the function of PU.1 is down-regulated by AML1-ETO in t(8;21) myeloid leukemia, whereas overexpression of PU.1 restores normal differentiation.