Influence of sacubitril/valsartan on hibernating myocardium in patients with chronic heart failure with reduced ejection fraction

Funding Acknowledgements

Type of funding sources: None.

Background

Myocardial viability particularly hibernating myocardium is one of the critical parameters for the assessment of the long-term prognosis of patients with ischemic etiology heart disease. Purpose of the study was to evaluate the influence of angiotensin receptor neprilysin inhibitor - sacubitril/valsartan on hibernating myocardium in patients with ischemic etiology chronic heart failure with reduced ejection fraction.

Material and Methods

One hundred and twenty patients with chronic heart failure with reduced ejection fraction (EF<40%) were enrolled in the study (mean age 58.2±14.6 years, male=53%). Patients were divided into two groups by sixty. Group I patients were assigned sacubitril/valsartan while Group II were assigned valsartan in addition to the standard treatment. Hibernating myocardium were assessed with echocardiography with dopamine test. All statistical analysis were assessed using STATA software.

Results

Ejection fraction and the wall motion score has been improved in both groups from baseline (P<0.05), however when we compared two groups, sacubitril/valsartan group tended to have more positive effect on ejection fraction (from 32.2±8.2% to 43.6±12.4% vs. from 31.7±8.0% to 37.2±10.3%, P<0.05) and the wall motion score (from 2.34±0.5 to 1.92±0.4 vs. 2.36±0.6 to 2.15±0.45, P<0.05) compared to valsartan group. Diastolic and systolic wall thickness has been improved in both groups from baseline (P<0.05), however there were not statistically significant changes between groups (P>0.05). When we analyzed by gender there were not significant changes between male and female (P<0.05).

Conclusion

Sacubitril/valsartan improves myocardial viability in patients with ischemic etiology chronic heart failure with reduced ejection fraction. Further studies with large amount of patients are required to clarify exact mechanisms.

Elicitation of pneumovirus-specific B cell responses by a prefusion-stabilized respiratory syncytial virus F subunit vaccine

Respiratory syncytial virus (RSV) is a substantial cause of morbidity and mortality globally. A candidate RSV prefusion (pre-F)-stabilized subunit vaccine, DS-Cav1, has previously been shown to elicit potent and durable neutralizing activity in a phase 1 clinical trial in healthy adults. Here, we used fluorescently labeled probes and flow cytometry to evaluate the antigen specificity and phenotype of RSV F-specific B cells longitudinally after DS-Cav1 immunization. Peripheral blood mononuclear cells (PBMCs) collected at time points before the first immunization through the end of the trial at 44 weeks were assessed by flow cytometry. Our data demonstrate a rapid increase in the frequency of pre-F-specific IgG⁺ and IgA⁺ B cells after the first immunization and a modest increase after a second immunization at week 12. Nearly all F-specific B cells down-regulated CD21 and up-regulated the proliferation marker CD71 after the first immunization, with less pronounced activation after the second immunization. Memory B cells (CD27⁺CD21⁺) specific for pre-F remained elevated above baseline at 44 weeks after vaccination. DS-Cav1 vaccination also activated human metapneumovirus (HMPV) cross-reactive B cells capable of binding prefusion-stabilized HMPV F protein and increased HMPV F-binding antibodies and neutralizing activity for HMPV in some participants. In summary, vaccination with RSV pre-F resulted in the expansion and activation of RSV and HMPV F-specific B cells that were maintained above baseline for at least 10 months and could contribute to long-term pneumovirus immunity.

Vaccination with prefusion-stabilized respiratory syncytial virus fusion protein induces genetically and antigenically diverse antibody responses

An effective vaccine for respiratory syncytial virus (RSV) is an unrealized public health goal. A single dose of the prefusion-stabilized fusion (F) glycoprotein subunit vaccine (DS-Cav1) substantially increases serum-neutralizing activity in healthy adults. We sought to determine whether DS-Cav1 vaccination induces a repertoire mirroring the pre-existing diversity from natural infection or whether antibody lineages targeting specific epitopes predominate. We evaluated RSV F-specific B cell responses before and after vaccination in six participants using complementary B cell sequencing methodologies and identified 555 clonal lineages. DS-Cav1-induced lineages recognized the prefusion conformation of F (pre-F) and were genetically diverse. Expressed antibodies recognized all six antigenic sites on the pre-F trimer. We identified 34 public clonotypes, and structural analysis of two antibodies from a predominant clonotype revealed a common mode of recognition. Thus, vaccination with DS-Cav1 generates a diverse polyclonal response targeting the antigenic sites on pre-F, supporting the development and advanced testing of pre-F-based vaccines against RSV.

Glycan Masking Focuses Immune Responses to the HIV-1 CD4-Binding Site and Enhances Elicitation of VRC01-Class Precursor Antibodies

An important class of HIV-1 broadly neutralizing antibodies, termed the VRC01 class, targets the conserved CD4-binding site (CD4bs) of the envelope glycoprotein (Env). An engineered Env outer domain (OD) eOD-GT8 60-mer nanoparticle has been developed as a priming immunogen for eliciting VRC01-class precursors and is planned for clinical trials. However, a substantial portion of eOD-GT8-elicited antibodies target non-CD4bs epitopes, potentially limiting its efficacy. We introduced N-linked glycans into non-CD4bs surfaces of eOD-GT8 to mask irrelevant epitopes and evaluated these mutants in a mouse model that expressed diverse immunoglobulin heavy chains containing human IGHV1-2^∗02, the germline VRC01 V_H segment. Compared to the parental eOD-GT8, a mutant with five added glycans stimulated significantly higher proportions of CD4bs-specific serum responses and CD4bs-specific immunoglobulin G⁺ B cells including VRC01-class precursors. These results demonstrate that glycan masking can limit elicitation of off-target antibodies and focus immune responses to the CD4bs, a major target of HIV-1 vaccine design.

Intra-lymph node injection of biodegradable polymer particles

Generation of adaptive immune response relies on efficient drainage or trafficking of antigen to lymph nodes for processing and presentation of these foreign molecules to T and B lymphocytes. Lymph nodes have thus become critical targets for new vaccines and immunotherapies. A recent strategy for targeting these tissues is direct lymph node injection of soluble vaccine components, and clinical trials involving this technique have been promising. Several biomaterial strategies have also been investigated to improve lymph node targeting, for example, tuning particle size for optimal drainage of biomaterial vaccine particles. In this paper we present a new method that combines direct lymph node injection with biodegradable polymer particles that can be laden with antigen, adjuvant, or other vaccine components. In this method polymeric microparticles or nanoparticles are synthesized by a modified double emulsion protocol incorporating lipid stabilizers. Particle properties (e.g. size, cargo loading) are confirmed by laser diffraction and fluorescent microscopy, respectively. Mouse lymph nodes are then identified by peripheral injection of a nontoxic tracer dye that allows visualization of the target injection site and subsequent deposition of polymer particles in lymph nodes. This technique allows direct control over the doses and combinations of biomaterials and vaccine components delivered to lymph nodes and could be harnessed in the development of new biomaterial-based vaccines.