Induction of Death Receptor CD95 and Co-stimulatory Molecules CD80 and CD86 by Meningococcal Capsular Polysaccharide-Loaded Vaccine Nanoparticles

Abstract

ABSTRACT. Neisseria meningitidis is a leading cause of bacterial meningitis and sepsis, and its capsular polysaccharides (CPS) are a major virulence factor in meningococcal infections and form the basis for serogroup designation and protective vaccines. We formulated a novel nanovaccine containing meningococcal CPS as an antigen encapsulated in albumin-based nanoparticles (NPs) that does not require chemical conjugation to a protein carrier. These nanoparticles are taken up by antigen-presenting cells and act as antigen depot by slowly releasing the antigen. In this study, we determined the ability of CPS-loaded vaccine nanoparticles to induce co-stimulatory molecules, namely CD80, CD86, and CD95 that impact effective antigen presentation. Co-stimulatory molecule gene induction and surface expression on macrophages and dendritic cells pulsed with meningococcal CPS-loaded nanoparticles were investigated using gene array and flow cytometry methods. Meningococcal CPS-loaded NP significantly induced the surface protein expression of CD80 and CD86, markers of dendritic cell maturation, in human THP-1 macrophages and in murine dendritic cells DC2.4 in a dose-dependent manner. The massive upregulation was also observed at the gene expression. However, high dose of CPSloaded NP, but not empty NP, induced the expression of death receptor CD95 (Fas) leading to reduced TNF-α release and reduction in cell viability. The data suggest that high expression of CD95 may lead to death of antigen-presenting cells and consequently suboptimal immune responses to vaccine. The CPSloaded NP induces the expression of co-stimulatory molecules and acts as antigen depot and can spare antigen dose, highly desirable criteria for vaccine formulations.

Analysis of novel meningococcal vaccine formulations

“…The recent advances in the field of nanotechnology facilitated the development of novel meningococcal vaccine formulation that mimics conjugation effects by encapsulation into albumin-based nanoparticle matrices. 8,13,14 The spherical shaped micro and nanoparticles are biological mimics of N. meningitidis bacteria, therefore present to immune system as invader but without the ability to cause disease. The novel meningococcal vaccine nanoparticles formulation encapsulates meningococcal CPS polymers in a biodegradable material that slowly release antigens, therefore enhance antigen presentation by exerting antigen depot effect.…”

“…The antigenicity of meningococcal vaccine delivered in nanoparticles is significantly higher when compared to vaccine delivered in solution. 13 In addition, the antigenicity of meningococcal vaccine nanoparticles formulation is greatly enhanced when combined with adjuvants like Alum or MF59 also encapsulated in nanoparticles. 8 These adjuvants are approved by Federal and Drug Administration (FDA) to be used with licensed vaccines.…”

“…Technically, human monocyte derived cells can serve as antigen presenting cells (APCs) when pulsed with various doses of vaccine antigens in a tissue culture plate scaled down to a 96-well microtiter plate as previously described. 8,13,14 An array of innate immune responses can be measured including cytokines release, phagocytosis, autophagy induction, cellular viability and apoptosis, as well as the expression of dendritic cell maturation and antigen presentation markers MHC I, MHC II, CD40, CD80, CD83 and CD86. 8,13,14,21 Meningococcal vaccine-induced innate immune responses Neisseria meningitidis capsular polysaccharides (CPS) that form the basis of vaccine, are recognized via TLR2 and TLR4-MD-2 and elicit the release of cytokines and chemokines from macrophages.…”

Nanoparticles in Vaccine Delivery

“…These include peptide amphiphile micelles [9], pH responsive polymer-based nanoparticles [10], cationic liposomes [11], polysaccharide-based nanoparticles [12], and nanoparticles formed from biodegradable polymers such as p o l y l a c t i c -c o -g l y c o l i d e ( P L G A ) [ 1 3 -1 5 ] and polyanhydrides [16]. This theme issue includes a comprehensive review by Jewell and colleagues on the topic of harnessing biomaterials to engineer the lymph node microenvironment for immunity or tolerance [17].…”

“…It was also shown that this vaccine strategy did not induce autoimmunity. D'Souza and colleagues report on the induction of death receptor CD95 and co-stimulatory molecules CD80 and CD86 by meningococcal capsular polysaccharide-loaded vaccine nanoparticles [12]. Neisseria meningitidis is the primary cause of bacterial meningitis and sepsis worldwide, and virulence is mostly dependent on capsular polysaccharides (CPS) that define at least 12 serogroups and are an attractive target for protective vaccines.…”