Sex differences in achieving guideline-recommended heart rate control among a large sample of patients at risk for sudden cardiac arrest.

Background: Despite known clinical benefits, guideline-recommended heart rate (HR) control is not achieved for a significant proportion of patients with HF with reduced ejection fraction. The wearable cardioverter-defibrillator (WCD) provides continuous HR monitoring and alerts that could aid medication titration. Objective: This study sought to evaluate sex differences in achieving guideline-recommended HR control during a period of WCD use. Methods: Data from patients fitted with a WCD from 2015 to 2018 were obtained from the manufacturer's database (ZOLL). The proportion of patients with adequate nighttime resting HR control at the beginning of use (BOU) and at the end of use (EOU) were compared by sex. Adequate HR control was defined as having a nighttime median HR <70 beats/min. Results: A total of 21,440 women and a comparative sample of 17,328 men (median 90 [IQR 59-116] days of WCD wear) were included in the final dataset. Among patients who did not receive a shock, over half had insufficient HR control at BOU (59% of women, 53% of men). Although the proportion of patients with resting HR ≥70 beats/min improved by EOU, 43% of women and 36% of men did not achieve guideline-recommended HR control. Conclusion: A significant proportion of women and men did not achieve adequate HR control during a period of medical therapy optimization. Compared with men, a greater proportion of women receiving WCD shocks had insufficiently controlled HR in the week preceding ventricular tachyarrhythmia/ventricular fibrillation and 43% of nonshocked women, compared with 36% of men, did not reach adequate HR control during the study period. The WCD can be utilized as a remote monitoring tool to record HR and inform adequate uptitration of beta-blockers, with particular focus on reducing the treatment gap in women.

Wearable Cardioverter Defibrillator-Guided 6-Min Walk Test Performed at Home Is Accurate and Reliable: RESULTS OF THE TRENDS STUDY.

PURPOSE: The 6-min walk test (6MWT) is broadly used to evaluate the functional ability of patients with heart failure (HF). The purpose of this study was to evaluate the accuracy and reliability of the wearable cardioverter defibrillator (WCD)-guided 6MWT performed at home by patients with HF versus in-clinic testing. METHODS: Patients (n = 197) with HF and a low ejection fraction prescribed a WCD were randomized to 2 groups. Group 1 completed an in-clinic clinician-guided 6MWT while wearing the WCD; results were recorded by the clinician. Group 2 completed a WCD-guided 6MWT, also performed in the clinic; results were recorded by the WCD accelerometer. Both groups performed weekly unsupervised WCD-guided 6MWTs at home, with results recorded by the WCD. RESULTS: The initial in-clinic 6MWT showed no significant group difference in distance walked (group 1 = 306 m; group 2 = 297 m). For patients in group 2 who completed at least one 6MWT at home, there was a 15-step decrease between the in-clinic WCD-guided 6MWT and the first at-home 6MWT, 558 and 543 median steps (P = .001), respectively. Among patients with at least 8 weekly home WCD-guided 6MWTs (n = 70), there was no significant difference in the number of steps walked during the 6MWT from week to week. CONCLUSIONS: Results of the in-clinic 6MWT are similar between clinician-guided and WCD-guided patients across objective distances. Distances walked with a WCD-guided walk test were consistent whether conducted in the clinic or at home and were reliable over time.

Long-term use of the wearable cardioverter defibrillator in patients with explanted ICD.

OBJECTIVES: To evaluate the effectiveness of wearable cardioverter defibrillator (WCD) use in protecting patients from sudden cardiac arrest (SCA) while they were treated in nonhospital settings until re-implantation of an Implantable cardioverter-defibrillator (ICD) was feasible. We sought to determine whether the WCD could be successfully utilized long term (≥1 year) after ICD extraction in patients at continued risk of SCD in which ICD re-implantation was not practical. BACKGROUND: ICDs have proven to improve mortality in patients for both secondary and primary prevention of SCA. Increased ICD implantation in older patients with comorbid conditions has resulted in higher rates of cardiac device infections. Currently, a wearable cardioverter defibrillator (WCD) is an alternative management for SCA prevention in specific cases. METHODS: This a retrospective analysis based on consecutive WCD patients who underwent ICD explant due to device-related infections or mechanical reasons between April 2007 and July 2014. A total of 102 patients were identified from the national database maintained by ZOLL (Pittsburgh, PA, USA). We analyzed the reason for WCD use, demographic information, device data, compliance and duration of WCD use, detected arrhythmias and therapies, and reason for discontinuing WCD use. RESULTS: In these long term WCD users, average length of WCD use was 638 ±â€¯361 days. Nine patients (8.8%) had a sustained ventricular arrhythmia that was successfully resuscitated by the WCD. Six patients (5.8%) experienced inappropriate shocks. Two patients (1.9%) died of asystole events while wearing the WCD and an additional 10 patients died while not monitored by the WCD. Thirty-nine patients (38.2%) ended WCD use when a new ICD was implanted and 15 patients (14.7%) were still wearing the WCD at the time of analysis. CONCLUSIONS: We found that extending use of the WCD to ≥1 year is a safe and effective alternative treatment for patients with explanted ICDs who are not pacemaker dependent.

The US Experience of the Wearable Cardioverter-Defibrillator in Pediatric Patients.

BACKGROUND: Certain pediatric patients are at risk for sudden cardiac death. The wearable cardioverter-defibrillator (WCD) can be used in clinical situations in which implantable cardioverter-defibrillator placement is not ideal. The objectives of the study are to examine the effectiveness, safety, and compliance of the WCD in the identification and treatment of life-threatening ventricular arrhythmias in pediatric patients. METHODS: All United States pediatric patients <18 years who wore a WCD, from 2009 to 2016 were retrospectively reviewed. RESULTS: In total, 455 patients were identified. The median age was 15 (3-17) years, median duration of WCD use was 33 (1-999) days and median patient wear time was 20.6 (0.3-23.8) hours per day. The population was divided into 2 groups: (1) patients with implantable cardioverter-defibrillator problem, n=63 and (2) patients with nonimplantable cardioverter-defibrillator problem, n=392. Wear time per day was >20 hours in both groups. Wear duration was shorter in the implantable cardioverter-defibrillator problem group, 26 days versus 35 days, P<0.05. There were 7 deaths (1.5%); all not wearing WCD at time of death. Eight patients (1.8%) received at least 1 WCD shock treatment. Of the 6 patients (1.3%) who had appropriate therapy, there were 7 episodes of either polymorphic ventricular tachycardia or ventricular fibrillation with a total of 13 treatments delivered. All episodes were successfully converted and the patients survived. CONCLUSIONS: The WCD has overall adequate compliance with appropriate wear times and wear durations in pediatric patients. The WCD is safe and effective in treating ventricular arrhythmias that can lead to sudden cardiac death in pediatric patients.

Outcomes after asystole events occurring during wearable defibrillator-cardioverter use.

AIM: To examine whether wearable cardioverter defibrillator (WCD) alarms for asystole improve patient outcomes and survival. METHODS: All asystole episodes recorded by the WCD in 2013 were retrospectively analyzed from a database of device and medical record documentation and customer call reports. Events were classified as asystole episodes if initial presenting arrhythmia was asystole (< 10 beats/minor ≥ 5 s pause). Survival was defined as recovery at the scene or arrival to a medical facility alive, or not requiring immediate medical attention. Episodes occurring in hospitals, nursing homes, or ambulances were considered to be under medical care. Serious asystole episodes were defined as resulting in unconsciousness, hospital transfer, or death. RESULTS: Of the total 51933 patients having worn the WCD in 2013, there were 257 patients (0.5%) who had asystole episodes and comprised the study cohort. Among the 257 patients (74% male, median age 69 years), there were 264 asystole episodes. Overall patient survival was 42%. Most asystoles were considered "serious" (n = 201 in 201 patients, 76%), with a 26% survival rate. All 56 patients with "non-serious" asystole episodes survived. Being under medical care was associated with worse survival of serious asystoles. Among acute survivors, 20% later died during WCD use (a median 4 days post asystole episode). Of the 86 living patients at the end of WCD use period, 48 (56%) received ICD/pacemaker and 17 (20%) improved their condition. CONCLUSION: Survival rates after asystole in patients with WCD are higher than historically reported survival rates. Those under medical care at time of asystole exhibited lower survival.

National experience with long-term use of the wearable cardioverter defibrillator in patients with cardiomyopathy.

PURPOSE: The wearable cardioverter defibrillator (WCD) is generally used for short periods of sudden cardiac death (SCD) risk; circumstances may occasionally result in prolonged use (over 1 year). The aim of this study was to determine the benefits and risks of prolonged use in patients with systolic heart failure (HF). METHODS: ZOLL's post-market US database included adult patients (≥18 years) with ischemic and/or non-ischemic cardiomyopathy (ICM, NICM) and at least 1 year of use. Cox-regression was used to identify factors associated with survival with WCD use, and reasons for stopping use were entered as time-dependent factors. RESULTS: Among 220 patients, age (mean ± SD) 55.4 ± 14.8 years, WCD use 451.4 ± 289.9 days, and 67.3 % were male and their left ventricle ejection fraction (EF) averaged 20.9 ± 7.2 %. Eighty-nine (40.5 %) were continuing WCD use at the last follow-up. Thirty-six (16.4 %) and 56 (25.5 %) patients discontinued WCD use because of EF recovery and implantable cardioverter (ICD) implantation, respectively. Nine patients (4.1 %) received appropriate shock therapy for 13 episodes of sustained ventricular tachyarrhythmia with 12 (92.3 %) successful shocks. One patient died of refractory ventricular fibrillation. One patient died from sinus bradycardia transitioning to asystole. Eight patients (3.6 %) had nine episodes of non-fatal inappropriate shocks. CONCLUSIONS: Long-term use of the WCD is safe and effective. Recovery of EF was seen in significant number of patients even after 1 year of WCD use.

The Wearable Cardioverter Defibrillator in Nonischemic Cardiomyopathy: A US National Database Analysis.

BACKGROUND: The wearable cardioverter defibrillator (WCD) is often used in patients at risk of sudden cardiac death (SCD) who are not yet candidates for an implantable cardioverter defibrillator (ICD). Newly diagnosed cardiomyopathy may be reversible, and a WCD may protect patients during the initial period of risk. We evaluate the benefit and compliance of the WCD in patients with nonischemic cardiomyopathy (NICM). METHODS: We reviewed a national database of patients with NICM who used WCDs and who self-reported a history of excess alcohol use, although other causes of cardiomyopathy could not be excluded. The database contained demographic data, initial ejection fraction (EF), reason for WCD prescription, compliance and use data, any detected arrhythmias, therapies, and reason for discontinuing WCD. Statistical analyses were performed using SAS, version 9.3 (SAS Institute, Cary, NC). RESULTS: Of the 127 patients, 88% were men with a mean age of 52.6 ± 11.0 years. The mean initial EF was 19.9% ± 7.4%. Patients wore the WCD for a median of 51 days and a median daily use of 18.0 hours per day. The most common reasons for discontinuing the WCD were improvement in EF (33%) or ICD implantation (23.6%). Seven patients (5.5%) had 9 sustained ventricular arrhythmia events, which were successfully treated with 100% conversion. There were 11 deaths (8.6%) during 100 days of follow-up. No deaths resulted from WCD shock failure or undersensing. CONCLUSIONS: NICM may have a significant risk of ventricular arrhythmias and death in the first few months. The WCD delivered appropriate therapy in 5.5% of patients. This study suggests that a WCD may be effective temporary prophylaxis for prevention of SCD in patients with newly diagnosed NICM.

Wearable cardioverter-defibrillator use in patients perceived to be at high risk early post-myocardial infarction.

OBJECTIVES: The aim of this study was to describe usage of the wearable cardioverter-defibrillator (WCD) during mandated waiting periods following myocardial infarction (MI) for patients perceived to be at high risk for sudden cardiac arrest (SCA). BACKGROUND: Current device guidelines and insurance coverage require waiting periods of either 40 days or 3 months before implanting a cardioverter-defibrillator post-myocardial infarction (MI), depending on whether or not acute revascularization was undertaken. METHODS: We assessed characteristics of and outcomes for patients who had a WCD prescribed in the first 3 months post-MI. The WCD medical order registry was searched for patients who were coded as having had a "recent MI with ejection fraction ≤35%" or given an International Classification of Diseases, Ninth Revision 410.xx diagnostic code (acute MI), and then matched to device-recorded data. RESULTS: Between September 2005 and July 2011, 8,453 unique patients (age 62.7 ± 12.7 years, 73% male) matched study criteria. A total of 133 patients (1.6%) received 309 appropriate shocks. Of these patients, 91% were resuscitated from a ventricular arrhythmia. For shocked patients, the left ventricular ejection fraction (LVEF) was ≤30% in 106, 30% to 35% in 17, >36% in 8, and not reported in 2 patients. Of the 38% of patients not revascularized, 84% had a LVEF ≤30%; of the 62% of patients revascularized, 77% had a LVEF ≤30%. The median time from the index MI to WCD therapy was 16 days. Of the treated patients, 75% received treatment in the first month, and 96% within the first 3 months of use. Shock success resulting in survival was 84% in nonrevascularized and 95% in revascularized patients. CONCLUSIONS: During the 40-day and 3-month waiting periods in patients post-MI, the WCD successfully treated SCA in 1.4%, and the risk was highest in the first month of WCD use. The WCD may benefit individual patients selected for high risk of SCA early post-MI.

Wearable defibrillator use in heart failure (WIF): results of a prospective registry.

BACKGROUND: Heart failure (HF) patients have a high risk of death, and implantable cardioverter defibrillators (ICDs) are effective in preventing sudden cardiac death (SCD). However, a certain percentage of patients may not be immediate candidates for ICDs, particularly those having a short duration of risk or an uncertain amount of risk. This includes the newly diagnosed patients, as well as those on the cardiac transplant list or NYHA class IV heart failure patients who do not already have an ICD. In these patients, a wearable cardioverter defibrillator (WCD) may be used until long term risk of SCD is defined. The purpose of this study was to determine the incidence of SCD in this population, and the efficacy of early defibrillation by a WCD. METHODS: Ten enrolling centers identified 89 eligible HF patients who were either listed for cardiac transplantation, diagnosed with dilated cardiomyopathy, or receiving inotropic medications. Data collected included medical history, device records, and outcomes (including 90 day mortality). RESULTS: Out of 89 patients, final data on 82 patients has been collected. Patients wore the device for 75±58 days. Mean age was 56.8±13.2, and 72% were male. Most patients (98.8%) were diagnosed with dilated cardiomyopathy with a low ejection fraction (<40%) and twelve were listed for cardiac transplantation. Four patients were on inotropes. There were no sudden cardiac arrests or deaths during the study. Interestingly, 41.5% of patients were much improved after WCD use, while 34.1% went on to receive an ICD. CONCLUSIONS: In conclusion, the WCD monitored HF patients until further assessment of risk. The leading reasons for end of WCD use were improvement in left ventricular ejection fraction (LVEF) or ICD implantation if there was no significant improvement in LVEF.

Characteristics and outcomes of peripartum versus nonperipartum cardiomyopathy in women using a wearable cardiac defibrillator.

BACKGROUND: Peripartum cardiomyopathy (PPCM) mortality rates vary between 2% and 56%, with half occurring ≤12 weeks'; postpartum. Although risk factors for PPCM have been identified, predicting sudden cardiac death among PPCM patients remains difficult. This study describes the characteristics and outcomes of PPCM patients and controls referred for a wearable cardioverter defibrillator (WCD). METHODS AND RESULTS: Deidentified WCD medical orders between 2003 and 2009 and death index searches were used to characterize women (ages 17-43) with PPCM (n = 107) or matched nonpregnant women with nonischemic dilated cardiomyopathy (NIDCM; n = 159). Demographics were similar. WCD use averaged 124 ± 123 days and 96 ± 83 days among PPCM and NIDCM patients, respectively. No PPCM patients received an appropriate shock for ventricular tachycardia/ventricular fibrillation; 1 NIDCM patient received 2 successful shocks. No PPCM patient died during WCD use versus 11 concurrent NIDCM deaths. After WCD use, 3 PPCM and 13 NIDCM patients died, respectively. CONCLUSIONS: The mortality rate of 2.8% (over 3.0 ± 1.2 years) in PPCM patients is low compared to published data. The role of WCD therapy among PPCM patients deserves further study.

Wearable defibrillator in congenital structural heart disease and inherited arrhythmias.

Patients with congenital structural heart disease (CSHD) and inherited arrhythmias (IAs) are at high risk of ventricular tachyarrhythmias and sudden cardiac death. The present study was designed to evaluate the short- and long-term outcomes of patients with CSHD and IA who received a wearable cardioverter-defibrillator (WCD) for the prevention of sudden cardiac death. The study population included 162 patients with CSHD (n = 43) and IA (n = 119) who were prospectively followed up in a nationwide registry from 2005 to 2010. The mortality rates were compared using Kaplan-Meier survival analysis. The mean age of the study patients was 38 ± 27 years. The patients with CSHD had a greater frequency of left ventricular dysfunction (ejection fraction <30%) than did the patients with IA (37% vs 5%, respectively; p = 0.002). The predominant indication for WCD was pending genetic testing in the IA group and transplant listing in the CSHD group. Compliance with the WCD was similar in the 2 groups (91%). WCD shocks successfully terminated 3 ventricular tachyarrhythmias in the patients with IA during a median follow-up of 29 days of therapy (corresponding to 23 appropriate WCD shocks per 100 patient-years). No arrhythmias occurred in the patients with CSHD during a median follow-up of 27 days. No patients died while actively wearing the WCD. At 1 year of follow-up, the survival rates were significantly lower among the patients with CSHD (87%) than among the patients with IA (97%, p = 0.02). In conclusion, our data suggest that the WCD can be safely used in high-risk adult patients with IA and CSHD. Patients with IA showed a greater rate of ventricular tachyarrhythmias during therapy but significantly lower long-term mortality rates.

Tumor-derived exosomes confer antigen-specific immunosuppression in a murine delayed-type hypersensitivity model.

Exosomes are endosome-derived small membrane vesicles that are secreted by most cell types including tumor cells. Tumor-derived exosomes usually contain tumor antigens and have been used as a source of tumor antigens to stimulate anti-tumor immune responses. However, many reports also suggest that tumor-derived exosomes can facilitate tumor immune evasion through different mechanisms, most of which are antigen-independent. In the present study we used a mouse model of delayed-type hypersensitivity (DTH) and demonstrated that local administration of tumor-derived exosomes carrying the model antigen chicken ovalbumin (OVA) resulted in the suppression of DTH response in an antigen-specific manner. Analysis of exosome trafficking demonstrated that following local injection, tumor-derived exosomes were internalized by CD11c+ cells and transported to the draining LN. Exosome-mediated DTH suppression is associated with increased mRNA levels of TGF-ß1 and IL-4 in the draining LN. The tumor-derived exosomes examined were also found to inhibit DC maturation. Taken together, our results suggest a role for tumor-derived exosomes in inducing tumor antigen-specific immunosuppression, possibly by modulating the function of APCs.

B7-1/2, but not PD-L1/2 molecules, are required on IL-10-treated tolerogenic DC and DC-derived exosomes for in vivo function.

Costimulatory molecules, such as B7-1/2 and PD-L1/2 play an important role in the function of APC. The regulation of the surface levels of costimulatory molecules is one mechanism by which APC maintain the balance between tolerance and immunity. We examined the contributions of B7-1/2 and PD-L1/2 to the function of IL-10-treated, immunosuppressive DC as well as therapeutic exosomes derived from these DC. IL-10 treatment of DC significantly downregulated surface expression of MHC II, B7-1, B7-2, and decreased levels of MHC I and PD-L2. IL-10 treatment of DC resulted in a modified costimulatory profile of DC-secreted exosomes with a reduction in B7-1, PD-L1 and PD-L2. We further demonstrate that absence of B7-1 or B7-2 on donor DC results in a loss of ability of IL-10-treated DC and their exosomes to suppress the delayed-type hypersensitivity response, whereas IL-10-treated DC deficient in PD-L1/2 as well as their secreted exosomes retained the ability to suppress delayed-type hypersensitivity responses. We conclude that B7-1 and B7-2, but not PD-L1 and PD-L2, on IL-10-treated DC and DC-derived exosomes play a critical role in immunosuppressive functions of both DC and exosomes.

Therapeutic effect of exosomes from indoleamine 2,3-dioxygenase-positive dendritic cells in collagen-induced arthritis and delayed-type hypersensitivity disease models.

OBJECTIVE: We have demonstrated previously that dendritic cells (DCs) modified with immunosuppressive cytokines, and exosomes derived from DCs can suppress the onset of murine collagen-induced arthritis (CIA) and reduce the severity of established arthritis. Indoleamine 2,3-dioxygenase (IDO) is a tryptophan-degrading enzyme that is important for immune regulation and tolerance maintenance. DCs expressing functional IDO can inhibit T cells by depleting them of essential tryptophan and/or by producing toxic metabolites, as well as by generating Treg cells. This study was undertaken to examine the immunosuppressive effects of bone marrow (BM)-derived DCs genetically modified to express IDO, and of exosomes derived from IDO-positive DCs. METHODS: BM-derived DCs were adenovirally transduced with IDO or CTLA-4Ig (an inducer of IDO), and the resulting DCs and exosomes were tested for their immunosuppressive ability in the CIA and delayed-type hypersensitivity (DTH) murine models. RESULTS: Both DCs and exosomes derived from DCs overexpressing IDO had an antiinflammatory effect in CIA and DTH murine models. The suppressive effects were partially dependent on B7 costimulatory molecules. In addition, gene transfer of CTLA-4Ig to DCs resulted in induction of IDO in the DCs and in exosomes able to reduce inflammation in an IDO-dependent manner. CONCLUSION: These results demonstrate that both IDO-expressing DCs and DC-derived exosomes are immunosuppressive and antiinflammatory, and are able to reverse established arthritis. Therefore, exosomes from IDO-positive DCs may represent a novel therapy for rheumatoid arthritis.

Modulation of the immune response using dendritic cell-derived exosomes.

Initial studies in our laboratory were focused on the use of dendritic cells (DC) genetically modified to express Th2-derived cytokines (i.e., interleukin [IL]-4 and IL-10) or apoptotic proteins (i.e., Fas Ligand [FasL]) to reduce inflammation in a mouse model of experimentally induced arthritis. Exosomes are nano-sized vesicles (40-100 nm diameter) released by different cell types, including DC, that contain many of the proteins thought to be involved in regulating the immune response. We have demonstrated that exosomes derived from immature DC treated with immunomodulatory cytokines (i.e., IL-10, IL-4) are able to inhibit inflammation in a murine footpad model of delayed-type hypersensitivity (DTH) and reduce the severity of established collagen-induced arthritis (CIA). In fact, the exosomes were as therapeutic as the parental DC. Because purified DC-derived exosomes are very stable vesicles, they may be a better approach for future treatment of arthritis and other autoimmune disorders than the more unstable DC. In this chapter we detail a protocol for preparing the exosomes produced by murine bone marrow-derived DC. We also review methods to assess the purity and concentration of purified exosomes, by using electron microscopy, Western blot analysis, and flow cytometry. Finally, we describe methods to assess the function of exosomes in vitro, using the mixed leukocytes reaction, and in vivo by means of DTH and an experimental model of CIA.

MHC class II+ exosomes in plasma suppress inflammation in an antigen-specific and Fas ligand/Fas-dependent manner.

Exosomes are 50- to 100-nm vesicles that are formed within the late endocytic compartment and released from a variety of cell types. Previously, we demonstrated that exosomes derived from dendritic cells transduced with adenoviral vectors expressing IL-10, IL-4, or Fas ligand (FasL) produce anti-inflammatory exosomes able to reduce inflammation in a murine paw delayed-type hypersensitivity model, suppress the onset on murine collagen-induced arthritis, and reduce the severity of established collagen-induce arthritis. In this study, we examined the ability of endogenous, blood-borne exosomes to regulate the immune response. Exosomes isolated from plasma of mice immunized to keyhole limpet hemocyanin, but not from naive or OVA-immunized mice, were able to suppress the keyhole limpet hemocyanin-specific delayed-type hypersensitivity inflammatory response. The anti-inflammatory effect was mediated by MHC class II(+) plasma exosomes that were also FasL(+) and CD11b(+), but CD11c(-). Moreover, the anti-inflammatory effect of the MHC class II(+) plasma-derived exosomes was, in part, dependent upon the presence of FasL in the exosomes and Fas in the recipient mouse. These results suggest that exosomes in the plasma, produced by MHC class II(+) and CD11b(+) cells, have the ability to suppress the immune response in an Ag-specific manner in part through a Fas/FasL-dependent manner.

Effective treatment of inflammatory disease models with exosomes derived from dendritic cells genetically modified to express IL-4.

In this study, we demonstrate that genetically modified bone marrow-derived dendritic cells (DC) and exosomes derived from the DC, expressing either secreted IL-4 or membrane-bound IL-4, can reduce the severity and the incidence of established collagen-induced arthritis and inhibit inflammation of delayed-type hypersensitivity (DTH) in mice. The ability of the DC and DC-derived exosomes to suppress the DTH response was MHC class II and, in part, Fas ligand/Fas dependent. The DC-derived exosomes were internalized by CD11c(+) DC in the dermis at the site of injection and in the draining lymph node as well as by CD11c(+) DC and F4/80(+) macrophages in the spleen. Moreover, adoptive transfer of CD11c(+) or CD3(+) splenic cells from mice treated with exosomes showed significant reduction of footpad swelling in the DTH model. These results demonstrate that administration of DC/IL-4 or exosomes derived from DC/IL-4 are able to modulate the activity of APC and T cells in vivo through a MHC class II and partly Fas ligand/Fas-dependent mechanism, resulting in effective treatment of established collagen-induced arthritis and suppression of the DTH inflammatory response. Thus, APC-derived exosomes could be used therapeutically for the treatment of autoimmune disease and inflammatory disorders.

Estrogen receptor regulation of quinone reductase in breast cancer: implications for estrogen-induced breast tumor growth and therapeutic uses of tamoxifen.

Antiestrogens have found widespread use in the treatment of breast cancer (reviewed in ref. 1). There is also interest in the use of tamoxifen as a preventive agent for breast cancer. However, the mechanism for the antitumor effects of antiestrogens is relatively unknown. For the most part it is thought that the basis for the anticancer action of antiestrogens is the inhibition of estradiol (E2)-stimulated tumor growth. We have observed however that antiestrogens can activate detoxifying enzymes, like quinone reductase (NQO1), which protect cells against the toxic and tumor-promoting effects of carcinogens (2). Studies characterizing the molecular mechanisms behind the regulation of NQO1 by the Estrogen Receptor (ER) support an important role of the ER in pathways regulating antioxidant defenses. Moreover these findings represent a novel mechanism through which antiestrogens function. The activation of NQO1 may contribute to the beneficial anticancer and antioxidant activity of antiestrogens in breast cancer and possibly other estrogen target tissues. It is possible that the basis for some of the anticancer action of antiestrogens is that the induction of NQO1 inhibits the genotoxic effects induced by the oxidative metabolism of estrogens.

Differential induction of quinone reductase by phytoestrogens and protection against oestrogen-induced DNA damage.

Quinone reductase (QR) is a phase II detoxification enzyme that plays an important role in detoxifying quinones and may help maintain the antioxidant function of the cell. We have previously observed that QR is up-regulated by anti-oestrogens, but not oestrogen, in breast cancer cells via ERbeta (oestrogen receptor beta) transactivation. Such QR induction appears to protect breast cells against oestrogen-induced oxidative DNA damage, most likely by reducing reactive oestrogen metabolites termed catecholestrogen-quinones back to the hydroxy-catecholestrogens which may be conjugated. We now report that the phytoestrogens biochanin A, genistein and resveratrol also up-regulate QR expression in breast cancer cells. We observe that regulation can occur at the transcriptional level, preferentially through ERbeta transactivation at the electrophile response element of the QR gene promoter. By chromatin immunoprecipitation analysis, we show binding of ERalpha and ERbeta to the QR promoter, with increased ERbeta binding in the presence of resveratrol. Functional studies show that biochanin A and resveratrol, but not genistein, can significantly protect against oestrogen-induced oxidative DNA damage in breast cancer cells. Antisense technology was used to determine whether such protection was dependent on ERbeta or QR. Our results with resveratrol are consistent with our hypothesis that the protective ability of resveratrol is partially dependent on the presence of ERbeta and QR. In conclusion, we postulate that phytoestrogen-mediated induction of QR may represent an additional mechanism for breast cancer protection, although the effects may be specific for a given phytoestrogen.

Functional implications of antiestrogen induction of quinone reductase: inhibition of estrogen-induced deoxyribonucleic acid damage.

Recent studies have shown that the antiestrogens tamoxifen and raloxifene may protect against breast cancer, presumably because of a blockade of estrogen receptor (ER)-mediated transcription. Another possible explanation is that antiestrogen-liganded ER transcriptionally induces genes that are protective against cancer. We previously reported that antiestrogen-liganded ERbeta transcriptionally activates the major detoxifying enzyme quinone reductase (QR) [NAD(P)H:quinone oxidoreductase]. It has been established that metabolites of estrogen, termed catecholestrogens, can form DNA adducts and cause oxidative DNA damage. We hypothesize that QR inhibits estrogen-induced DNA damage by detoxification of reactive catecholestrogens. We report here that physiological concentrations of 17beta-estradiol cause oxidative DNA damage, as measured by levels of 8- hydroxydeoxyguanine, in ER-positive MCF7 breast cancer cells, MDA-MB-231 breast cancer cells (ERalpha negative/ERbeta positive) and nontumorigenic MCF10A breast epithelial cells (very low ER), which is dependent on estrogen metabolism. Estrogen-induced 8-hydroxydeoxyguanine was inversely correlated to QR and ERbeta levels and was followed by downstream induction of the DNA repair enzyme XPA. Trans-hydroxytamoxifen, raloxifene, and the pure antiestrogen ICI-182,780 protected against estradiol-mediated damage in breast cancer cells containing ERbeta. This is most likely due to the ability of these antiestrogens to activate expression of QR via ERbeta. We conclude that up-regulation of QR, either by overexpression or induction by tamoxifen, can protect breast cells against oxidative DNA damage caused by estrogen metabolites, representing a possible novel mechanism of tamoxifen prevention against breast cancer.