Decidual NK Cells Transfer Granulysin to Selectively Kill Bacteria in Trophoblasts.

Maternal decidual NK (dNK) cells promote placentation, but how they protect against placental infection while maintaining fetal tolerance is unclear. Here we show that human dNK cells highly express the antimicrobial peptide granulysin (GNLY) and selectively transfer it via nanotubes to extravillous trophoblasts to kill intracellular Listeria monocytogenes (Lm) without killing the trophoblast. Transfer of GNLY, but not other cell death-inducing cytotoxic granule proteins, strongly inhibits Lm in human placental cultures and in mouse and human trophoblast cell lines. Placental and fetal Lm loads are lower and pregnancy success is greatly improved in pregnant Lm-infected GNLY-transgenic mice than in wild-type mice that lack GNLY. This immune defense is not restricted to pregnancy; peripheral NK (pNK) cells also transfer GNLY to kill bacteria in macrophages and dendritic cells without killing the host cell. Nanotube transfer of GNLY allows dNK to protect against infection while leaving the maternal-fetal barrier intact.

The Kaposi's sarcoma-associated herpesvirus viral interleukin 6 gene affects metastasis and expression of B cell markers in a murine xenograft model.

Kaposi's sarcoma-associated herpesvirus (KSHV) is a cancer-causing virus in humans, primarily affecting AIDS patients. KSHV causes a range of cancers including Kaposi's sarcoma, pleural effusion lymphoma and multicentric Castleman's disease. Current methods available for treating these cancers are relatively ineffective, and new targets for therapy are needed. The KSHV viral homolog of interleukin-6 gene (vIL-6) may play a significant role in tumor development and may serve as a new anti-cancer target, but its role in tumor formation is only partially understood. Here, a novel animal model was used to study how vIL-6 affects tumor development. Highly immune-deficient Rag2-/-γc-/- mice were transplanted with an immortalized human B cell line (BJAB) harboring either wild-type (WT) KSHV or a mutant strain lacking vIL-6 ΔvIL-6). Solid tumors developed and total tumor mass and the number of tumors were characterized. The vIL-6 gene had no significant impact on tumor mass, but significantly more tumors were detected when vIL-6 was present. Significant differences in expression of B cell markers in cells from extracted tumors were detected based upon the presence of vIL-6. B cell markers in tumor cells were also compared to the same cell type in culture, prior to xenotransplantation; B cell markers were mostly downregulated during tumor formation and these changes did not differ based upon the presence of vIL-6. The only marker that significantly increased in expression during tumor development was CD30. Tumor blood vessels were quantified to determine if more angiogenesis occurred with vIL-6-expressing virus, but there was no significant difference. These data indicate that vIL-6 plays a role in KSHV tumor formation in B cells in vivo. Further investigation into how vIL-6 manipulates CD30 expression may shed insight into KSHV oncogenesis, and may identify how vIL-6 can be targeted.

Genome Sequences of 19 Novel Erwinia amylovora Bacteriophages.

Erwinia amylovora is the causal agent of fire blight, a devastating disease affecting some plants of the Rosaceae family. We isolated bacteriophages from samples collected from infected apple and pear trees along the Wasatch Front in Utah. We announce 19 high-quality complete genome sequences of E. amylovora bacteriophages.