T Cells Aid in Limiting Pathogen Burden and in Enhancing B1 and B2 Cell Antibody Responses to Membrane Glycolipid and the Surface Lipoprotein Decorin-Binding Protein A during Borrelia burgdorferi Infection: A Dissertation

Murine infection by the Lyme disease spirochete, B. burgdorferi, results in the generation of pathogen-specific antibody that can provide protection against Lyme disease, but the cells involved in this response are poorly characterized. T cells are not required for generating a protective antibody response to B. burgdorferi infection, but their exact role in providing protection against tissue colonization had not been previously determined. We found that TCRβxδ;-/- mice were susceptible to high pathogen loads and decreased antibody titers, but inhibition of CD40L-dependent interactions resulted in partial protection suggesting that a portion of the help provided by T cells was not dependent on CD40L-CD40 interactions between T and B cells. RAG1-/- mice reconstituted with either un-fractionated or B1-enriched peritoneal cells from previously infected mice generated B. burgdorferi-specific antibody, and upon spirochetal challenge suffered significantly lower levels of pathogen load in the joint and heart. Peritoneal cells from previously infected TCRβxδ-/- mice or B2-enriched or B1-purified peritoneal cells conferred little to only moderate protection, suggesting T cells play an important role in protection against spirochetal infection the joint. Consistent with this, T cells from previously infected donor mice, when transferred with B1 or B2 cells into RAG1-/- mice, generated increased antibody titers and were capable of diminishing bacterial burden in the joint and heart. A previously identified class of protective antibody is directed against the spirochetal surface lipoprotein DbpA, and we found that DbpA is a prominent protein antigen recognized by RAG1-/- mice reconstituted with B1-enriched peritoneal cells. Additionally, we found that mice reconstituted with B1 cells also make antibody directed towards the spirochetal glycolipid antigen, BbGL-IIc, which is recognized by Vα14iNKT cells. Consistent with the idea that T cells are important in providing protection against spirochetal infection, RAG1-/- mice reconstituted with B1 and T cells generated a more robust response against DbpA and BbGL-IIc. These results support the hypothesis that T cells act with B1 cells in a CD40L-independent manner to promote the production of antibodies that play an important role in protection of the joint from spirochetal infection.Immunology and Microbiolog

(De-) Oiling Inflammasomes

Activation of inflammasome signaling can produce harmful inflammation. In this issue of Immunity, Yan et al. (2013) suggest that omega-3 fatty acids commonly found in marine oils can suppress activation of NLRP3 and NLRP1b inflammasomes

(De-) oiling inflammasomes

Activation of inflammasome signaling can produce harmful inflammation. In this issue of Immunity, Yan et al. (2013) suggest that omega-3 fatty acids commonly found in marine oils can suppress activation of NLRP3 and NLRP1b inflammasomes

Inflammasomes and host defenses against bacterial infections

The inflammasome has emerged as an important molecular protein complex which initiates proteolytic processing of pro-IL-1β and pro-IL-18 into mature inflammatory cytokines. In addition, inflammasomes initiate pyroptotic cell death that may be independent of those cytokines. Inflammasomes are central to elicit innate immune responses against many pathogens, and are key components in the induction of host defenses following bacterial infection. Here, we review recent discoveries related to NLRP1, NLRP3, NLRC4, NLRP6, NLRP7, NLRP12 and AIM2-mediated recognition of bacteria. Mechanisms for inflammasome activation and regulation are now suggested to involve kinases such as PKR and PKCδ, ligand binding proteins such as the NAIPs, and caspase-11 and caspase-8 in addition to caspase-1. Future research will determine how specific inflammasome components pair up in optimal responses to specific bacteria

Inflammasomes and host defenses against bacterial infections

The inflammasome has emerged as an important molecular protein complex which initiates proteolytic processing of pro-IL-1β and pro-IL-18 into mature inflammatory cytokines. In addition, inflammasomes initiate pyroptotic cell death that may be independent of those cytokines. Inflammasomes are central to elicit innate immune responses against many pathogens, and are key components in the induction of host defenses following bacterial infection. Here, we review recent discoveries related to NLRP1, NLRP3, NLRC4, NLRP6, NLRP7, NLRP12 and AIM2-mediated recognition of bacteria. Mechanisms for inflammasome activation and regulation are now suggested to involve kinases such as PKR and PKCδ, ligand binding proteins such as the NAIPs, and caspase-11 and caspase-8 in addition to caspase-1. Future research will determine how specific inflammasome components pair up in optimal responses to specific bacteria

Serum cytokine profiles associated with specific adjuvants used in a DNA prime-protein boost vaccination strategy.

In recent years, heterologous prime-boost vaccines have been demonstrated to be an effective strategy for generating protective immunity, consisting of both humoral and cell-mediated immune responses against a variety of pathogens including HIV-1. Previous reports of preclinical and clinical studies have shown the enhanced immunogenicity of viral vector or DNA vaccination followed by heterologous protein boost, compared to using either prime or boost components alone. With such approaches, the selection of an adjuvant for inclusion in the protein boost component is expected to impact the immunogenicity and safety of a vaccine. In this study, we examined in a mouse model the serum cytokine and chemokine profiles for several candidate adjuvants: QS-21, Al(OH)3, monophosphoryl lipid A (MPLA) and ISCOMATRIX™ adjuvant, in the context of a previously tested pentavalent HIV-1 Env DNA prime-protein boost formulation, DP6-001. Our data revealed that the candidate adjuvants in the context of the DP6-001 formulation are characterized by unique serum cytokine and chemokine profiles. Such information will provide valuable guidance in the selection of an adjuvant for future AIDS vaccine development, with the ultimate goal of enhancing immunogenicity while minimizing reactogenicity associated with the use of an adjuvant. More significantly, results reported here will add to the knowledge on how to include an adjuvant in the context of a heterologous prime-protein boost vaccination strategy in general

Adjuvant-dependent cytokine profiles in the context of a DNA prime-protein boost HIV vaccine (113.23)

Abstract Heterologous prime-boost vaccination approaches have emerged as a promising strategy to generate protective immunity against a variety of pathogens in animal and human studies. Our previous studies demonstrated that HIV-1 gp120 DNA vaccine prime-protein boost elicits improved neutralizing antibody responses. To understand the mechanisms that regulate the immune responses in prime-boost vaccination strategy, current studies were designed to define the cytokine profiles associated with different adjuvants used in such regimens. A polyvalent vaccine DP6-001, including gp120 antigens from 5 different primary viral isolates, was used as the model vaccine. Any influence of endotoxin associated with DNA plasmid preparation was first excluded, as regular DNA preparations did not elicit different immune response when tested in vivo against endotoxin-free DNA preparations. Next we studied the effects of several adjuvants, QS-21, alum, and MPL, on the immunogenicity of DP6-001 in a mouse model. gp120-specific antibody and T cell responses, and innate cytokine production, were monitored at time points after immunizations and at termination. Our results indicate that different adjuvants may generate unique cytokine profiles and improve the immunogenicity of DP6-001. This study may provide valuable information in selection of an adjuvant for inclusion in future prime-boost vaccination strategies, with the goal of enhancing immunogenicity while minimizing reactogenicity.</jats:p