Ligand-competent fractalkine receptor is expressed on exosomes

Expression of chemokine receptor CX3CR1 is reportedly restricted to several cell types including natural killer cells, cytotoxic T cells, monocytes, and macrophages. However, its expression and function on exosomes, which are nanosized extracellular vesicles known to act as mediators of intercellular communications, remain unclear. Here, we investigated CX3CR1 expression on exosomes isolated from various cell types. Although we found that all the exosomes tested in our study highly expressed CX3CR1, this chemokine receptor was expressed only inside, but barely on, their source cells. Moreover, exosomal CX3CR1 was capable of binding soluble CX3CL1. Therefore, our study suggests that CX3CR1 is a novel and ligand-competent exosome receptor.     

Plasmodium berghei: quantitation of in vitro effects of antimalarial drugs on exoerythrocytic development by a ribosomal RNA probe

A stage-specific ribosomal RNA probe has been used to quantitate exoerythrocytic development of Plasmodium berghei in primary cultures of mouse hepatocytes. Parasite rRNA could be detected as soon as 6 hr after sporozoite invasion and was increased during schizogony to a maximum at 48 hr, when mature schizonts were identified by microscopy. As few as 10 exoerythrocytic schizonts could be detected by filter blot hybridization, followed by autoradiography and liquid scintillation counting. By hybridizing the culture rRNA samples with either parasite-specific or universal rRNA probes, the in vitro tissue schizonticidal activity and hepatotoxicity of primaquine, two of its analogues, and pyrimethamine, could be assessed. After a 48-hr exposure of the culture to serial dilutions of each drug, a quantitative relationship was demonstrated between the decrease of the parasite rRNA and the increase of the drug concentrations. No significant parasite-specific rRNA could be detected at the concentration achieving complete inhibition of schizont formation but causing no cytotoxic effects on host hepatocytes. In contrast to microscopic-based assays, this molecular approach provides an objective and quantitative in vitro method for rapid screening and evaluation of tissue schizonticidal antimalarials.     

Irisin supports integrin-mediated cell adhesion of lymphocytes

Irisin, a myokine released from skeletal muscle, has recently been found to act as a ligand for the integrins αVβ5, αVβ1, and α5β1 expressed on mesenchymal cells, thereby playing an important role in the metabolic remodeling of the bone, skeletal muscle and adipose tissues. Although the immune-modulatory effects of irisin in chronic inflammation have been documented, its interactions with lymphocytic integrins have yet to be elucidated. Here, we show that irisin supports the cell adhesion of human and mouse lymphocytes. Cell adhesion assays using a panel of inhibitory antibodies to integrins have shown that irisin-mediated lymphocyte adhesion involves multiple integrins including not only α4β1 and α5β1, but also leukocyte-specific αLβ2 and α4β7. Importantly, mouse lymphocytic TK-1 cells that lack the expression of β1 integrins have exhibited αLβ2- and α4β7-mediated cell adhesion to irisin. Irisin has also been demonstrated to bind to purified recombinant integrin αLβ2 and α4β7 proteins. Thus, irisin represents a novel ligand for integrin αLβ2 and α4β7, capable of supporting lymphocyte cell adhesion independently of β1 integrins. These results suggest that irisin may play an important role in regulating lymphocyte adhesion and migration in the inflamed vasculature.     

Prevalence of human papillomavirus infection,distribution of viral types and risk factors in cervical samples from human immunodeficiency virus-positive women attending three human immunodeficiency virus-acquired immune deficiency syndrome reference centres in northeastern Brazil

Human immunodeficiency virus (HIV)-positive patients have a greater prevalence of coinfection with human papillomavirus (HPV) is of high oncogenic risk. Indeed, the presence of the virus favours intraepithelial squamous cell lesion progression and may induce cancer. The aim of this study was to evaluate the prevalence of HPV infection, distribution of HPV types and risk factors among HIV-positive patients. Cervical samples from 450 HIV-positive patients were analysed with regard to oncotic cytology, colposcopy and HPV presence and type by means of polymerase chain reaction and sequencing. The results were analysed by comparing demographic data and data relating to HPV and HIV infection. The prevalence of HPV was 47.5%. Among the HPV-positive samples, 59% included viral types of high oncogenic risk. Multivariate analysis showed an association between HPV infection and the presence of cytological alterations (p = 0.003), age greater than or equal to 35 years (p = 0.002), number of partners greater than three (p = 0.002), CD4⁺ lymphocyte count < 200/mm³ (p = 0.041) and alcohol abuse (p = 0.004). Although high-risk HPV was present in the majority of the lesions studied, the low frequency of HPV 16 (3.3%), low occurrence of cervical lesions and preserved immunological state in most of the HIV-positive patients were factors that may explain the low occurrence of precancerous cervical lesions in this population.     

Kinetics of uranous iron and ferrous iron oxidation by thiobacillus ferrooxidans

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