Interaction of sex and diabetes in Asian patients with heart failure with mildly reduced left ventricular ejection fraction.

INTRODUCTION: The impact of sex and diabetes mellitus (DM) on patients with heart failure with mildly reduced ejection fraction (HFmrEF) is not well elucidated. This study aims to evaluate sex differences in the clinical profile and outcomes in Asian HFmrEF patients with and without DM. METHODS: Patients admitted nationally for HFmrEF (ejection fraction 40-49%) between 2008 and 2014 were included and followed up until December 2016. The primary outcome was all-cause mortality. Secondary outcomes included cardiovascular (CV) death and/or heart failure (HF) rehospitalisations. RESULTS: A total of 2,272 HFmrEF patients (56% male) were included. More women had DM than men (60% versus 55%, P=0.013). Regardless of DM status, HFmrEF females were older, less likely to smoke, had less coronary artery disease, narrower QRS and lower haemoglobin compared to men. The odds of having DM decreases in smokers who are women as opposed to men (Pinteraction =0.017). In multivariate analysis, DM reached statistical analysis for all-cause mortality and combined CV mortality or HF rehospitalisation in both men and women. However, the results suggest that there may be sex differences in terms of outcomes. DM (vs non-DM) was less strongly associated with increased all-cause mortality (adjusted hazards ratio [adj HR] 1.234 vs adj HR 1.290, Pinteraction <0.001] but more strongly associated with the combined CV death/HF rehospitalisation (adj HR 1.429 vs adj HR 1.317, Pinteraction =0.027) in women (vs men). CONCLUSION: Asian women with HFmrEF had a higher prevalence of DM, with differences in clinical characteristics, compared to men. While diabetes conferred poor outcomes regardless of sex, there were distinct sex differences. These highlight the need for sex-specific management strategies.

The role of pre-existing cross-reactive antibodies in determining the efficacy of vaccination in humans: study protocol for a randomized controlled trial.

BACKGROUND: Epidemic viral diseases have become more prevalent.. Among the various strategies to prevent such epidemics, vaccination is the most cost-effective. However, populations that are immunized are typically already exposed to multiple previous vaccinations or natural infections. Studies from this and other laboratories have revealed that pre-existing dengue antibodies can either inhibit or enhance subsequent dengue infection depending on the pre-existing antibody levels. While cross-reactive antibody is potentially pathogenic in dengue, how it impacts immune response to vaccination is unclear. Aggregated at the site of vaccination and the respective draining lymph nodes are antigen-presenting and immune regulatory cells that express Fc receptors and play pivotal roles in determining the magnitude and polarity of the immune response. Vaccine uptake by these antigen-presenting cells may thus be either inhibited or enhanced when vaccines are opsonized with cross-reactive antibodies. DESIGN: In view of the limited knowledge on how cross-reactive antibodies affect vaccination outcome, we propose a study that exploits the known cross reactivity between Japanese encephalitis (JE) virus antibody and yellow fever (YF) vaccine. We hypothesize that cross-reactive antibodies impact antibody response to YF at the point vaccination in a concentration-dependent manner by altering both vaccine uptake and the innate immune response by antigen presenting cells. We will structure an open-label clinical trial on sequential vaccination with JE and YF vaccines, with different time intervals between vaccinations. This would test immune response to YF vaccination in subjects with different titer of cross-reactive JE vaccine-derived antibodies. The clinical materials obtained in the trial will drive basic laboratory investigations directed at elucidating how heterologous antibody affect vaccination at the molecular level. YF neutralizing antibody titer will be measured using plaque reduction neutralization test against the vaccine strain YF17D. Innate immune response will be characterized genetically using either microarray or digital PCR (or both). The innate immune response will also be characterized at the protein and metabolite level using Luminex bead technology and lipidomic/metabolomic approaches. DISCUSSION: This proposed study represents one of the first to examine the role of cross-reactive antibodies in modulating immune responses to vaccines, the findings of which may re-shape vaccination strategy. TRIAL REGISTRATION: Clinical Trials.gov registration number: NCT01943305 (3 September 2013).