Dendritic cell-based immunization ameliorates pulmonary infection with highly virulent Cryptococcus gattii.

Cryptococcosis due to a highly virulent fungus, Cryptococcus gattii, emerged as an infectious disease on Vancouver Island in Canada and surrounding areas in 1999, causing deaths among immunocompetent individuals. Previous studies indicated that C. gattii strain R265 isolated from the Canadian outbreak had immune avoidance or immune suppression capabilities. However, protective immunity against C. gattii has not been identified. In this study, we used a gain-of-function approach to investigate the protective immunity against C. gattii infection using a dendritic cell (DC)-based vaccine. Bone marrow-derived dendritic cells (BMDCs) efficiently engulfed acapsular C. gattii (Δcap60 strain), which resulted in their expression of costimulatory molecules and inflammatory cytokines. This was not observed for BMDCs that were cultured with encapsulated strains. When Δcap60 strain-pulsed BMDCs were transferred to mice prior to intratracheal R265 infection, significant amelioration of pathology, fungal burden, and the survival rate resulted compared with those in controls. Multinucleated giant cells (MGCs) that engulfed fungal cells were significantly increased in the lungs of immunized mice. Interleukin 17A (IL-17A)-, gamma interferon (IFN-γ)-, and tumor necrosis factor alpha (TNF-α)-producing lymphocytes were significantly increased in the spleens and lungs of immunized mice. The protective effect of this DC vaccine was significantly reduced in IFN-γ knockout mice. These results demonstrated that an increase in cytokine-producing lymphocytes and the development of MGCs that engulfed fungal cells were associated with the protection against pulmonary infection with highly virulent C. gattii and suggested that IFN-γ may have been an important mediator for this vaccine-induced protection.

Identification of aberrant transcription termination at specific gene loci with DNA hypomethylated transcription termination sites caused by DNA methyltransferase deficiency.

CpG methylation of genomic DNA is a well-known repressive epigenetic marker in eukaryotic transcription, and DNA methylation of promoter regions is correlated with gene silencing. In contrast to the promoter regions, the function of DNA methylation during transcription termination remains to be elucidated. A recent study revealed that mouse DNA methyltransferase 3a (Dnmt3a) mainly functions in de novo methylation in the promoter and gene body regions, including transcription termination sites (TTSs), during development. To investigate the relationship between DNA methylation overlapping the TTSs and transcription termination, we performed bioinformatics analysis using six pre-existing Dnmt-/- mouse cell datasets: four types of neurons (three Dnmt3a-/- and one Dnmt1-/- mutants) and two types of embryonic fibroblasts (MEFs) (Dnmt3a-/- and Dnmt3b-/- mutants). Combined analyses using methylome and transcriptome data revealed that read counts downstream of hypomethylated TTSs were increased in three types of neurons (two Dnmt3a-/- and one Dnmt1-/- mutants). Among these, an increase in chimeric transcripts downstream of the TTSs was observed in Dnmt3a-/- mature olfactory sensory neurons and Dnmt3a-/- agouti-related peptide (protein)-producing neurons, thereby indicating that read-through occurs in hypomethylated TTSs at specific gene loci in these two mutants. Conversely, in Dnmt3a-/- MEFs, we detected reductions in read counts downstream of hypomethylated TTSs. These results indicate that the hypomethylation of TTSs can both positively and negatively regulate transcription termination, dependent on Dnmt and cell types. This study is the first to identify the aberrant termination of transcription at specific gene loci with DNA hypomethylated TTSs attributable to Dnmt deficiency.

Development and characterization of a unique anti-IgE mouse monoclonal antibody cross-reactive between human and canine IgE.

BACKGROUND: The efficacy assessment of human anti-IgE monoclonal antibodies (mAbs) in animal models before clinical trials is hampered due to the lack of cross-reactivity of anti-IgE mAbs between species. OBJECTIVE: We developed CRE-DR (an anti-dog IgE monoclonal antibody), an anti-IgE mouse mAb that recognizes canine and human IgE, and then examined its IgE specificity and cross-reactivity between three animal and human species. METHODS: After mouse immunization with a synthetic peptide derived from canine IgE (282 NTNDWIEGETYYC294 ), we generated a hybridoma producing CRE-DR. The CRE-DR purified from the ascites of hybridoma-inoculated mice was used for ELISA and Western blot analysis to examine reactivity to dog, human, and rodent IgEs as well as recombinant bovine serum albumin (BSA)-conjugated to canine, human, and rodent IgE amino acid peptides corresponding to the immunizing sequence. We then performed enzyme-linked immunosorbent assays (ELISAs) for dog IgE using sera from dogs with atopic dermatitis (AD) after inhibition with canine IgE and IgG. The amino acid sequence recognized by CRE-DR was identified by ELISA using synthetic peptides. RESULTS: CRE-DR is a monoclonal mouse IgG1κ specific for dog IgE, and the ELISA values in atopic dog sera were inhibited by dog IgE, but not dog IgG. The binding of CRE-DR to human IgE was relatively maintained, but not to rodent IgEs, which results were confirmed with the BSA-conjugated IgE peptides of the various species. The CRE-DR reactivity was supported by the comparison of amino acid sequence of CRE-DR epitope, DWIEGETYYC, in dog IgE; one, two, and three amino acids were substituted in the human, rat, and mouse IgE epitopes, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: CRE-DR is a mAb cross-reactive to dog and human IgEs, which can allow the use of a dog model of allergy to test the efficacy of a CRE-DR-derived anti-IgE therapeutic mAb before human clinical trials.