Tumor formation involves the accumulation of a series of genetic alterations that are required for malignant growth. In most malignancies, genetic changes can be observed at the chromosomal level as losses or gains of whole or large portions of chromosomes. Here we provide evidence that tumor DNA may be horizontally transferred by the uptake of apoptotic bodies. Phagocytosis of apoptotic bodies derived from H-ras V12 -and human c-myc-transfected rat fibroblasts resulted in loss of contact inhibition in vitro and a tumorigenic phenotype in vivo. Fluorescence in situ hybridization analysis revealed the presence of rat chromosomes or of rat and mouse fusion chromosomes in the nuclei of the recipient murine cells. The transferred DNA was propagated, provided that the transferred DNA conferred a selective advantage to the cell and that the phagocytotic host cell was p53-negative. These results suggest that lateral transfer of DNA between eukaryotic cells may result in aneuploidy and the accumulation of genetic changes that are necessary for tumor formation.

Human immunodeficiency virus type 1 (HIV-1) infection of dendritic cells (DCs

Dendritic cells (DCs) are antigen-presenting cells with the capacity to prime naive T cells for efficient cellular responses against pathogens such as HIV-1. DCs are also susceptible to HIV-1 infection, which may impair their ability to induce immunity. Here, we examined the ability of HIV-1-infected, in vitro-derived DCs to respond to CD40 ligand (CD40L) stimulation with the aim to study events during early HIV-1 infection. HIV-1 BaL -infected p24 ؉ DCs were detected after only 3 days of exposure to highly concentrated virus. We show that HIV-1-infected DCs upregulated costimulatory molecules, but were skewed in their production of effector cytokines in response to CD40L stimulation. CD40L stimulation induced significant secretion of tumor necrosis factor ␣ (TNF␣) and interleukin 12 (IL-12) p70 from both HIV-1-exposed and unexposed DCs. Intracellular stainings of HIV-1-exposed DCs revealed that TNF␣ could be detected in both the p24 ؊ and p24 ؉ DCs, but IL-12 p70 could be found only in the p24 ؊ DCs. Thus, although p24 ؉ DCs showed a mature phenotype similar to p24 ؊ DCs after CD40L stimulation, they appeared to have an impaired cytokine profile. These observations suggest that HIV-1 infection disables DC function, a phenomenon that may be relevant for optimal induction of HIV-1-specific immune responses.

No abstract

Mucosal inflammation is characterized by increased expression of proinflammatory cytokines and chemoattractant chemokines, resulting in infiltration of immunocompetent cells. This study compared the degree of mucosal inflammation in human immunodeficiency virus type 1 (HIV-1)-infected gut mucosa with that in tissue samples from subjects with inflammatory bowel disease (IBD) and from healthy seronegative control subjects. Gut mucosal biopsy specimens were immunohistochemically stained and were evaluated by in situ imaging. There was significantly increased expression of HIV-1 coreceptors CCR5 and CXCR4, beta-chemokine RANTES, and macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, as well as increased numbers of T cells in lamina propria of HIV-1-infected patients. The results were similar in patients with IBD and in HIV-1-infected patients, suggesting increased inflammation in the colon of HIV-1-infected patients. To further investigate the effect of inflammation in HIV-1-infected lamina propria, treatments that reduce immune activation in lamina propria must be evaluated.

Nanoparticles accumulate a plethora of host factors on their surface (protein corona) in biological fluids, which influence the nanoparticle activity. Here we provide evidence for the existence of a rich viral protein corona and show its implications for viral infectivity, immune cell activation and catalysis of amyloid aggregation. We demonstrate that respiratory syncytial virus (RSV), a major cause of respiratory tract infections, accumulates a distinctive protein corona in different biofluids including: human plasma, human bronchoalveolar lavage fluid, non-human primate plasma and fetal bovine serum. Additionally, corona pre-coating differentially affects viral infectivity and its ability to activate human monocyte-derived dendritic cells (moDCs) depending on the biofluid.Furthermore, we demonstrate that cell-free RSV can bind and catalyze the amyloid aggregation of an amyloidogenic peptide derived from the islet amyloid polypeptide (IAPP) via surface-assisted nucleation.Similarly, we show that herpes simplex virus 1 (HSV-1) catalyzes the amyloid aggregation of the amyloid-beta (Aβ 42 ) peptide which is the major constituent of amyloid plaques in Alzheimer's disease. Our results provide a proof-of-concept for the presence of a viral protein corona layer that is dependent on the microenvironment and influences viral-host interactions. Additionally, the demonstration of viral nanosurface driven amyloid catalysis in an extracellular environment illustrates convergence between viral and amyloid pathologies suggesting a novel mechanistic link that warrants further investigation.

No abstract

Recognition of nucleic acids by endosomal Toll-like receptors (TLR) is essential to combat pathogens, but requires strict control to limit inflammatory responses. The mechanisms governing this tight regulation are unclear. We found that single-stranded oligonucleotides (ssON) inhibit endocytic pathways used by cargo destined for TLR3/4/7 signaling endosomes. Both ssDNA and ssRNA conferred the endocytic inhibition, it was concentration dependent, and required a certain ssON length. The ssON-mediated inhibition modulated signaling downstream of TLRs that localized within the affected endosomal pathway. We further show that injection of ssON dampens dsRNA-mediated inflammatory responses in the skin of non-human primates. These studies reveal a regulatory role for extracellular ssON in the endocytic uptake of TLR ligands and provide a mechanistic explanation of their immunomodulation. The identified ssON-mediated interference of endocytosis (SOMIE) is a regulatory process that temporarily dampens TLR3/4/7 signaling, thereby averting excessive immune responses.