Involvement of Specific Mechanism in Plasmid DNA Uptake by Mouse Peritoneal Macrophages

Guo

The Journal of Immunology

et al. 2011

The utility of DNA vaccines has been limited by their failure to elicit sufficiently potent immune responses in many human applications, whereas DNA vaccinations in mice have been very successful. However, the underlying mechanisms remain unknown. We hypothesize that serum amyloid P component (SAP), which has a species-specific, DNA-binding ability, contributes to the differences between human and mice and then limits DNA vaccine’s efficacy in vivo. In our study, DNA vaccine-induced adaptive immune responses were also significantly decreased in the human SAP (hSAP) transgenic mice. Using human promonocytic cell line THP-1–derived macrophages as a cell model, we found that cells incubated with a hSAP–DNA complex showed significant defects in innate immune activations, whereas mouse SAP had similar, albeit very weak, activities. hSAP also significantly inhibited the functions of two identified DNA sentinels, high-mobility group B protein 1 and antimicrobial peptide LL37, and redirected DNA update to FcRs leading to endocytosis and endosomal degradation. We also found that a chemical SAP inhibitor strongly recovered the suppressed innate immune responses to DNA in the presence of human serum and enhanced the immunogenicity of DNA vaccines in vivo. Our data indicated that SAP is a key negative regulator for innate immune responses to DNA and may be partly responsible for the insufficient immune responses after DNA vaccinations in humans. SAP suppression may be a novel strategy for improving efficacy of human DNA vaccines and requires further clinical investigations.

Section: Hsap Changes Dna Uptake Manner From Macropinocytosis To Endosupporting

confidence: 92%

Human Serum Amyloid P Functions as a Negative Regulator of the Innate and Adaptive Immune Responses to DNA Vaccines

Guo

The Journal of Immunology

et al. 2011

“…Several membrane proteins have been shown to play a role in binding and uptake of natural and synthetic DNA, but with the exception of Mac-1 and Scavenger Receptor A (SRA), putative oligonucleotide binding proteins have not been characterized either structurally or functionally [36,[41][42][43][44][45][46]. Benimetskaya et al [31] demonstrated that Mac-1 can bind oligonucleotides, but its role as a protein involved in binding of high molecular weight DNA has not yet been addressed.…”

Section: Discussionmentioning

confidence: 99%

“…This conclusion is supported by the finding that neutrophil stimulation by bacterial DNA also occurs under Ca 2+ -and Mg 2+ -free conditions. We performed a number of experiments designed to analyze involvement of SRA in neutrophil activation by bacterial DNA; agents such as polyinosinic acid, dextran sulfate, and fucoidan, which block DNA binding to SRA [43][44][45][46], exhibited intrinsic neutrophil stimulatory activity (not shown), perhaps reflecting their capacity to interact with molecules other than SRA, such as CD18 and L-selectin [47,48]. More importantly, all the agents additively potentiated neutrophil activation induced by bacterial DNA, suggesting that SRA is not involved in this process (Trevani, unpublished results).…”

Section: Discussionmentioning

confidence: 99%

Bacterial DNA activates human neutrophils by a CpG‐independent pathway

et al. 2003

Bacterial DNA stimulates macrophages, monocytes, B lymphocytes, NK cells, and dendritic cells in a CpG-dependent manner. In this work we demonstrate that bacterial DNA, but not mammalian DNA, induces human neutrophil activation as assessed by L-selectin shedding, CD11b upregulation, and stimulation of cellular shape change, IL-8 secretion, and cell migration. Induction of these responses is not dependent on the presence of unmethylated CpG motifs, as neutrophil stimulatory properties were neither modified by CpG-methylation of bacterial DNA nor reproduced by oligonucleotides bearing CpG motifs. We found that human neutrophils express Toll-like receptor (TLR) 9 mRNA. However, as expected for a CpG-independent mechanism, activation does not involve a TLR9-dependent signaling pathway; neutrophil stimulation was not prevented by immobilization of bacterial DNA or by wortmannin or chloroquine, two agents that inhibit TLR9 signaling. Of note, both singlestranded and double-stranded DNA were able to induce activation, suggesting that neutrophils might be activated by bacterial DNA at inflammatory foci even in the absence of conditions required to induce DNA denaturation. Our findings provide the first evidence that neutrophils might be alerted to the presence of invading bacteria through recognition of its DNA via a novel mechanism not involving CpG motifs.

“…The involvement of scavenger receptors in the hepatic uptake of pDNA has also been supported by a single-pass rat perfusion study 75) and an uptake study using primary cultured mouse peritoneal macrophages. 76,77) …”

Section: Distribution Characteristic Of Pdna Following the Systemic Imentioning

confidence: 99%

Lipid Carrier Systems for Targeted Drug and Gene Delivery

2005

Self Cite

For effective chemotherapy, it is necessary to deliver therapeutic agents selectively to their target sites, since most drugs are associated with both beneficial effects and side effects. The use of lipid dispersion carrier systems, such as lipid emulsions and liposomes, as carriers of lipophilic drugs has attracted particular interest. A drug delivery system can be defined as a methodology for manipulating drug distribution in the body. Since drug distribution depends on the carrier, administration route, particle size of the carrier, lipid composition of the carrier, electric charge of the carrier and ligand density of the targeting carrier, these factors must be optimized. Recently, the lipid carrier system has also been applied to gene delivery systems for gene therapy. However, in both drug and gene medicine cases, a lack of cell-selectivity limits the wide application of this kind of drug and/or gene therapy. Therefore, lipid carrier systems for targeted drug and gene delivery must be developed for the rational therapy. In this review, we shall focus on the progress of research into lipid carrier systems for drug and gene delivery following systemic or local injection.