Organometallic nucleosides induce non-classical leukemic cell death that is mitochondrial-ROS dependent and facilitated by TCL1-oncogene burden

Background

Redox stress is a hallmark of the rewired metabolic phenotype of cancer. The underlying dysregulation of reactive oxygen species (ROS) is interconnected with abnormal mitochondrial biogenesis and function. In chronic lymphocytic leukemia (CLL), elevated ROS are implicated in clonal outgrowth and drug resistance. The pro-survival oncogene T-cell leukemia 1 (TCL1) is causally linked to the high threshold towards classical apoptosis in CLL. We investigated how aberrant redox characteristics and bioenergetics of CLL are impacted by TCL1 and if this is therapeutically exploitable.

Methods

Bio-organometallic chemistry provided compounds containing a cytosine nucleobase, a metal core (ferrocene, ruthenocene, Fe(CO)₃), and a 5’-CH2O-TDS substituent. Four of these metal-containing nucleoside analogues (MCNA) were tested for their efficacy and mode of action in CLL patient samples, gene-targeted cell lines, and murine TCL1-transgenic splenocytes.

Results

The MCNA showed a marked and selective cytotoxicity towards CLL cells. MCNA activity was equally observed in high-risk disease groups, including those of del11q/del17p cytogenetics and of clinical fludarabine resistance. They overcame protective stromal cell interactions. MCNA-evoked PARP-mediated cell death was non-autophagic and non-necrotic as well as caspase- and P53-independent. This unconventional apoptosis involved early increases of ROS, which proved indispensible based on mitigation of MCNA-triggered death by various scavengers. MCNA exposure reduced mitochondrial respiration (oxygen consumption rate; OCR) and induced a rapid membrane depolarization (∆ΨM). These characteristics distinguished the MCNA from the alkylator bendamustine and from fludarabine. Higher cellular ROS and increased MCNA sensitivity were linked to TCL1 expression. The presence of TCL1 promoted a mitochondrial release of in part caspase-independent apoptotic factors (AIF, Smac, Cytochrome-c) in response to MCNA. Although basal mitochondrial respiration (OCR) and maximal respiratory capacity were not affected by TCL1 overexpression, it mediated a reduced aerobic glycolysis (lactate production) and a higher fraction of oxygen consumption coupled to ATP-synthesis.

Conclusions

Redox-active substances such as organometallic nucleosides can confer specific cytotoxicity to ROS-stressed cancer cells. Their P53- and caspase-independent induction of non-classical apoptosis implicates that redox-based strategies can overcome resistance to conventional apoptotic triggers. The high TCL1-oncogenic burden of aggressive CLL cells instructs their particular dependence on mitochondrial energetic flux and renders them more susceptible towards agents interfering in mitochondrial homeostasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0378-1) contains supplementary material, which is available to authorized users.

Sleep-disordered breathing and inappropriate defibrillator shocks in chronic heart failure

PURPOSE

Supraventricular tachyarrhythmias are a major cause of inappropriate defibrillator shocks. Sleep-disordered breathing (SDB) is a known risk factor for atrial fibrillation (AF). We hypothesized that Cheyne-Stokes respiration (CSA) and obstructive sleep apnea (OSA) have an impact on inappropriate defibrillator discharges in patients witch chronic heart failure (CHF) and cardiac resynchronization therapy with defibrillator (CRT-D).

METHODS

In this study, 172 patients with CHF (LVEF ≤ 45 %, NYHA-class ≥ 2) and CRT-D underwent overnight polygraphy; 54 had no SDB (apnea-hypopnea index < 5/h), 59 had OSA, and 59 had CSA. During follow-up (36 months), inappropriate defibrillator shocks were documented.

RESULTS

In all, 17 patients had inappropriate defibrillator shocks (9.9 %; eight oversensing due to lead fractures, five caused by atrial fibrillation, four because of sinus tachycardia). Mean event-free survival time was 33.5 ± 1.2 months in the CSA group, 35.2 ± 0.7 months in the OSA group, and 32.1 ± 1.5 months in the no SDB group, respectively (CSA vs. no SDB p = 0.63; OSA vs. no SDB p = 0.31; CSA vs. OSA p = 0.45). Stepwise Cox proportional hazard regression analysis revealed an independent association for age (per year: hazard ratio 0.90, 95 % confidence interval 0.85-0.96, p < 0.001), but not for any kind of SDB.

CONCLUSIONS

SDB was not associated with inappropriate defibrillator shocks. We assume this is due to the low incidenceand low proportion of inappropriate therapies in response to AF.

Involvement of Toll-like receptors on Helicobacter pylori-induced immunity

Dendritic cells (DCs) play a major role in the innate immune response since they recognize a broad repertoire of PAMPs mainly via Toll-like receptors (TLRs). During Helicobacter pylori (H. pylori) infection, TLRs have been shown to be important to control cytokine response particularly in murine DCs. In the present study we analyzed the effect of blocking TLRs on human DCs. Co-incubation of human DCs with H. pylori resulted in the release of the pro-inflammatory cytokines IL-12p70, IL-6 and IL-10. Release of IL-12p70 and IL-10 was predominantly influenced when TLR4 signaling was blocked by adding specific antibodies, suggesting a strong influence on subsequent T cell responses through TLR4 activation on DCs. Co-incubation of H. pylori-primed DC with allogeneic CD4+ T cells resulted in the production of IFN-γ and IL-17A as well as the expression of Foxp3, validating a mixed Th1/Th17 and Treg response in vitro. Neutralization of TLR4 during H. pylori infection resulted in significantly decreased amounts of IL-17A and IFN-γ and reduced levels of Foxp3-expressing and IL-10-secreting T cells. Our findings suggest that DC cytokine secretion induced upon TLR4-mediated recognition of H. pylori influences inflammatory and regulatory T cell responses, which might facilitate the chronic bacterial persistence.

A new peroral mother-baby endoscope system for biliary tract disorders

AIM: To investigate a new mother-baby system, consisting of a peroral cholangioscope and a duodenoscope in patients regarding its feasibility.

METHODS: In the study period from January 2007 to February 2010, 76 consecutive patients (33 men, 43 women; mean age 63 years old) were included in this pilot series. Endoluminal images and biopsies were obtained from 55 patients with indeterminate strictures, while 21 patients had fixed filling defects. The diagnostic accuracy of peroral cholangioscopy (POCS) in the visualization of strictures and tissue sampling was evaluated, and therapeutic success was monitored. Follow-up was performed over at least 9 mo.

RESULTS: A total of 55 patients had indeterminate strictures. Using the criteria “circular stenosis” and “irregular surface or margins”, POCS correctly described 27 out of 28 malignant biliary strictures and 25 out of 27 benign lesions (sensitivity, 96.4%; specificity, 92.6%, diagnostic accuracy 94.5%). Visually targeted forceps biopsies were performed in 55 patients. Tissue sampling during POCS revealed malignancy in 18 of 28 cases (sensitivity: 64.3%). In 21 patients with fixed filling defects, 10 patients with bile duct stones were successfully treated with conventional stone removal. Nine patients with difficult stones (5 giant stones and 4 intrahepatic stones) were treated with visually guided laser lithotripsy. Two patients in the group with unclear fixed filling defects had bile duct adenoma or papillary tumors and were surgically treated.

CONCLUSION: The new 95 cm POCS allows for accurate discrimination of strictures and fixed filling defects in the biliary tree, provides improved sensitivity of endoscopically guided biopsies and permits therapeutic approaches for difficult intrahepatic stones.

Echocardiographic particle image velocimetry for the evaluation of diastolic function in hypertrophic nonobstructive cardiomyopathy

AIMS

To use particle image velocimetry (PIV) echocardiography for the evaluation of diastolic dysfunction (DD) in patients with hypertrophic nonobstructive cardiomyopathy (HNCM).

METHODS

This study included 50 individuals, thereof 30 patients with DD due to HNCM and 20 healthy individuals who served as controls. HNCM patients were divided into 3 groups according to DD severity. All subjects underwent clinical assessment, exercise testing, and standard as well as PIV echocardiography.

RESULTS

Energy dissipation was higher in DD patients than in the control group. The severity of flow pattern disturbance corresponded to the degree of DD. In a subgroup of 20 HNCM patients we found significant correlations between invasive measured left ventricular end-diastolic pressure and noninvasive PIV parameters for intraventricular pressure differences and filling. Inter-observer variability (mean difference ± 1.96 SD) for all tested PIV measurements was good.

CONCLUSION

According to DD severity, patients with HNCM have disturbed intraventricular flow and reduced intraventricular pressure differences, consistent with a reduced intraventricular suction. PIV echocardiography appears to be feasible for detailed analysis of ventricular vortex flow in DD conditions. Further research using PIV echocardiography in different cardiac pathologies seems warranted.

Determining the role of fibrosis in hypertrophic cardiomyopathy

Fibroblast activity within the heart may be considered a basically constructive process. Hyperactivity of fibroblasts, however, may result in the accumulation of extracellular matrix proteins with adverse effects on cardiac structure and function including electrical instability and increased risk of arrhythmogenic cardiac death. The detection of cardiac fibrosis by dedicated imaging techniques, mainly gadolinium-enhanced MRI, holds promise to refine patient management in a variety of cardiac conditions. This review aims to summarize the current knowledge regarding fibrosis in hypertrophic cardiomyopathy.

Sleep-disordered breathing in patients undergoing transfemoral aortic valve implantation for severe aortic stenosis

BACKGROUND

We examined the prevalence of sleep-disordered breathing (SDB) in patients with severe aortic valve stenosis (AS) and the impact of transfemoral aortic valve implantation (TAVI) on SDB.

METHODS

79 patients underwent cardiorespiratory polygraphy (PG) before TAVI (CoreValve™), 62 of them a second PG after the procedure.

RESULTS

Forty-nine (62 %) patients had obstructive sleep apnea (OSA), 25 (32 %) central sleep apnea (CSA), and 5 (6 %) presented without significant SDB (apnea-hypopnea index (AHI) < 5/h). Among the 62 patients evaluated before and after TAVI, 36 (58 %) had OSA, 22 (36 %) CSA, and 4 patients (7 %) no SDB. AHI was significantly higher in CSA patients than in OSA patients (34.5 ± 18.3 vs. 18.0 ± 12.6/h, p < 0.001). Successful TAVI had a significant impact on CSA but not on OSA: CSA patients with optimal TAVI results experienced a significant reduction in central respiratory events (AHI 39.6 ± 19.6-23.1 ± 16.0/h, p = 0.035), while no changes were detected in OSA patients (AHI 18.8 ± 13.0-20.25 ± 13.4/h, p = 0.376). In contrast, in patients who developed at least moderate periprosthetic aortic regurgitation (AR > I), CSA increased significantly (AHI 26.3 ± 13.2-39.2 ± 18.4/h, p = 0.036), whereas no acute change was seen in patients with OSA (AHI 10.5 ± 7.8-12.5 ± 5.0/h, p = 0.5).

CONCLUSION

OSA and CSA are prevalent in more than 90 % of patients undergoing TAVI for severe aortic valve stenosis. Successful TAVI had no significant impact on OSA but improved CSA. In case of an acute change from pressure overload (aortic stenosis) to acute volume overload (aortic regurgitation after TAVI), central, but not obstructive, sleep apnea deteriorated.

Impact of Obstructive Sleep Apnoea on Type 2 Diabetes and Vice Versa

Type 2 diabetes and obstructive sleep apnoea (OSA) are diseases with high prevalence and major public health impact. There is evidence that OSA is independently associated with alterations in glucose metabolism. Furthermore, OSA is a significant risk factor for the development of type 2 diabetes. Possible causes might be intermittent hypoxaemia and sleep fragmentation with increased oxidative stress and sympathetic activity, which are typical features of OSA. OSA might also be a reason for ineffective treatment of type 2 diabetes. There is further evidence that the treatment of OSA by continuous positive airway pressure (CPAP) therapy might improve glucose metabolism. On the other hand, there are also hints in the literature that type 2 diabetes might induce sleep apnoea, especially in patients with autonomic neuropathy, but that OSA also facilitates the development of neuropathy in terms of mutual interactions between OSA, type 2 diabetes and diabetic neuropathy. Based on the current scientific data, clinicians have to be aware of the relations between OSA and type 2 diabetes, both from the sleep medical and the diabetological point of view.

Treatment of Cheyne-Stokes respiration reduces arrhythmic events in chronic heart failure

OBJECTIVE

This study aimed to investigate whether adequate treatment of Cheyne-Stokes respiration (CSR) reduces the risk of arrhythmic events in patients with chronic heart failure (CHF).

METHODS

A cohort of 403 registry patients with CHF (LVEF≤45%, NYHA-class≥2) and implanted cardioverter-defibrillator devices (ICD) was studied. They underwent overnight polygraphy, with 221 having mild or no CSR (apnea-hypopnea index [AHI]<15/h), and 182 having moderate to severe CSR (AHI>15/h). Latter ones were offered therapy with adaptive servoventilation (ASV), which 96 patients accepted and 86 rejected. During follow-up (21± 15 months) defibrillator therapies were recorded in addition to clinical and physiologic measures of heart failure severity.

RESULTS

Event-free survival from (a) appropriate cardioverter-defibrillator therapies and (b) appropriately monitored ventricular arrhythmias was shorter in the untreated CSR group compared to the treated CSR and the no CSR group. Stepwise Cox proportional hazard regression analysis showed untreated CSR (a: hazard ratio [HR] 1.99, 95% confidence interval [CI] 1.46-2.72, P < 0.001; b: HR 2.19, 95%CI 1.42-3.37, P < 0.001), but not treated CSR (a: HR 1.06, 95%CI 0.74-1.50; P = 0.77; b: HR 1.21, 95%CI 0.75-1.93, P = 0.43) was an independent risk factor. The treated CSR group showed improvements in cardiac function and respiratory stability compared to the untreated CSR group.

CONCLUSION

This study demonstrates a decrease of appropriate defibrillator therapies by ASV treated CSR in patients with CHF and ICD. A reduced exposure to hyperventilation, hypoxia, and improvement in indices of CHF severity and neurohumoral disarrangements are potential causative mechanisms.

The importance of training in echocardiography: a validation study using pocket echocardiography

AIMS

To investigate the training effect in echocardiography by using recent hand-held ultrasound scanners (HANDs).

METHODS

In this prospective study, 320 consecutive patients were scanned with HAND by an inexperienced ultrasonographer over a period of 8 weeks. Imaging studies were compared with high-end echocardiography as gold standard. Segmental endocardial border delineation was scored to describe image quality. Assessment of left ventricular dimensions, regional/global left ventricular function and grading of valve disease were compared.

RESULTS

A significant reduction in examination duration, improvement in image quality, substantial agreement in functional assessment (κ > 0.61, P < 0.01) and wall motion scoring (κ=0.67, P < 0.01) could be observed over time. The correlation in left ventricular measurements was excellent (r > 0.98, P < 0.01). The detection of valve diseases and pericardial effusions was sufficient, but the grading only moderate (κ < 0.6).

CONCLUSION

Well-grounded training in echocardiography leads to a rapid improvement in image acquisition and interpretation over a period of a few weeks. Basic diagnostic findings could be interpreted with high accuracy after short training. Interpretation of complex findings remained difficult. The time needed to carry out an examination using pocket echocardiography could not be reduced to less than 3-4 min per patient. New educational concepts are warranted.

Endoscopic stent therapy in patients with chronic pancreatitis: A 5-year follow-up study

AIM: This study analyzed clinical long-term outcomes after endoscopic therapy, including the incidence and treatment of relapse.

METHODS: This study included 19 consecutive patients (12 male, 7 female, median age 54 years) with obstructive chronic pancreatitis who were admitted to the 2^nd Medical Department of the Technical University of Munich. All patients presented severe chronic pancreatitis (stage III°) according to the Cambridge classification. The majority of the patients suffered intermittent pain attacks. 6 of 19 patients had strictures of the pancreatic duct; 13 of 19 patients had strictures and stones. The first endoscopic retrograde pancreatography (ERP) included an endoscopic sphincterotomy, dilatation of the pancreatic duct, and stent placement. The first control ERP was performed 4 wk after the initial intervention, and the subsequent control ERP was performed after 3 mo to re-evaluate the clinical and morphological conditions. Clinical follow-up was performed annually to document the course of pain and the management of relapse. The course of pain was assessed by a pain scale from 0 to 10. The date and choice of the therapeutic procedure were documented in case of relapse.

RESULTS: Initial endoscopic intervention was successfully completed in 17 of 19 patients. All 17 patients reported partial or complete pain relief after endoscopic intervention. Endoscopic therapy failed in 2 patients. Both patients were excluded from further analysis. One failed patient underwent surgery, and the other patient was treated conservatively with pain medication. Seventeen of 19 patients were followed after the successful completion of endoscopic stent therapy. Three of 17 patients were lost to follow-up. One patient was not available for interviews after the 1^st year of follow-up. Two patients died during the 3^rd year of follow-up. In both patients chronic pancreatitis was excluded as the cause of death. One patient died of myocardial infarction, and one patient succumbed to pneumonia. All three patients were excluded from follow-up analysis. Follow-up was successfully completed in 14 of 17 patients. 4 patients at time point 3, 2 patients at time point 4, 3 patients at time point 5 and 2 patients at time point 6 and time point 7 used continuous pain medication after endoscopic therapy. No relapse occurred in 57% (8/14) of patients. All 8 patients exhibited significantly reduced or no pain complaints during the 5-year follow-up. Seven of 8 patients were completely pain free 5 years after endoscopic therapy. Only 1 patient reported continuous moderate pain. In contrast, 7 relapses occurred in 6 of the 14 patients. Two relapses were observed during the 1^st year, 2 relapses occurred during the 2^nd year, one relapse was observed during the 3^rd year, one relapse occurred during the 4^th year, and one relapse occurred during the 5^th follow-up year. Four of these six patients received conservative treatment with endoscopic therapy or analgesics. Relapse was conservatively treated using repeated stent therapy in 2 patients. Analgesic treatment was successful in the other 2 patients.

CONCLUSION: 57% of patients exhibited long-term benefits after endoscopic therapy. Therefore, endoscopic therapy should be the treatment of choice in patients being inoperable or refusing surgical treatment.

[The "asymptomatic" patient with chronic acquired heart valve disease]

An intervention for chronic acquired valvular heart disease may either be indicated in symptomatic patients to relieve symptoms and improve quality of life or in asymptomatic patients to improve long-term prognosis, e.g., by preventing disease-related complications like chronic heart failure or arrhythmias. For proper action according to current guidelines, the systematic evaluation of symptoms related to the underlying valve disease is of utmost importance. If a discrepancy between symptoms reported or not reported by the patients and the severity of the valve disease is supposed, true absence of symptoms and exercise tolerance should be verified by spiroergometry. In the truly asymptomatic patient with a severe valvular lesion, preservation of myocardial adaption to the chronic volume or pressure overload should be tested utilizing appropriate imaging techniques like radionuclide ventriculography under exercise conditions. The proper evaluation of the functional status is of growing importance in our aging population with its sedentary lifestyle. In this context, the results of a survey should be kept in mind, which indicated that a significant proportion of patients still have interventions too late during the natural history of their valve disease with symptoms of congestive heart failure, arrhythmias, and the risk of sudden cardiac death persisting after a primarily successful valve repair or replacement.