Asian Zika virus can acquire generic African-lineage mutations during in utero infection.

The Zika virus 2015 epidemic showed an unusual phenotype for human flaviviruses, specifically fetal infection. We previously showed that in utero inoculation with the Asian Zika virus isolated from the human sample causes persistent infection in porcine fetuses. Here, we characterized the evolution of the Asian Zika virus in the fetal brain and placenta. Interestingly, the Asian Zika virus acquired generic African lineage K101R (A408G) and R1609 K (G4932A) mutations during in utero infection. Both African mutations were nonsynonymous and had a high frequency of nearly 100% in the fetal brain. Then, we synthetically generated the wild-type Asian variant and fetal brain-specific variant with generic African-lineage K101R and R1609 K mutations. In mosquito C6/36 cells, but not in human and pig cells, the fetal brain-specific variant showed higher virus loads compared to the Asian wild-type prototype. While in utero infection with both variants caused comparable virus loads in the placenta and amniotic fluids, fetuses injected with the fetal brain-specific variant had the trend to higher virus loads in lymph nodes. Also, introduced K101R and R1609 K mutations were stable and had high nearly 100% frequency at 28 days after in utero inoculation in both directly injected and trans-infected fetuses. These findings evoke concerns because Zika persists in pig herds and mosquitoes on farms in Mexico. It will be essential to identify how persistent in utero infection affects virus evolution and whether in utero-emerged Zika variants have the potential for shedding into the environment, more efficient transmission, and more aggressive infection phenotypes.

Deficiency of leukocyte-specific protein 1 (LSP1) alleviates asthmatic inflammation in a mouse model.

BACKGROUND: Asthma is a major cause of morbidity and mortality in humans. The mechanisms of asthma are still not fully understood. Leukocyte-specific protein-1 (LSP-1) regulates neutrophil migration during acute lung inflammation. However, its role in asthma remains unknown. METHODS: An OVA-induced mouse asthma model in LSP1-deficient (Lsp1-/-) and wild-type (WT) 129/SvJ mice were used to test the hypothesis that the absence of LSP1 would inhibit airway hyperresponsiveness and lung inflammation. RESULTS: Light and electron microscopic immunocytochemistry and Western blotting showed that, compared with normal healthy lungs, the levels of LSP1 were increased in lungs of OVA-asthmatic mice. Compared to Lsp1-/- OVA mice, WT OVA mice had higher levels of leukocytes in broncho-alveolar lavage fluid and in the lung tissues (P < 0.05). The levels of OVA-specific IgE but not IgA and IgG1 in the serum of WT OVA mice was higher than that of Lsp1-/- OVA mice (P < 0.05). Deficiency of LSP1 significantly reduced the levels of IL-4, IL-5, IL-6, IL-13, and CXCL1 (P < 0.05) but not total proteins in broncho-alveolar lavage fluid in asthmatic mice. The airway hyper-responsiveness to methacholine in Lsp1-/- OVA mice was improved compared to WT OVA mice (P < 0.05). Histology revealed more inflammation (inflammatory cells, and airway and blood vessel wall thickening) in the lungs of WT OVA mice than in those of Lsp1-/- OVA mice. Finally, immunohistology showed localization of LSP1 protein in normal and asthmatic human lungs especially associated with the vascular endothelium and neutrophils. CONCLUSION: These data show that LSP1 deficiency reduces airway hyper-responsiveness and lung inflammation, including leukocyte recruitment and cytokine expression, in a mouse model of asthma.

Integrin alpha-v/beta3 expression in equine lungs and jejunum.

Integrin alpha-v/beta3 (αvß3) recognizes arginine-glycine-aspartic acid (RGD) sequences and has important functions in cell adhesion, signaling, and survival. However, the expression of integrin αvß3 in the equine lungs and jejunum is not well understood. The objective of this study was to explore the hitherto unknown expression of integrin αvß3 in the lungs and jejuna of the horse using light and electron immunocytochemistry. Immunohistochemistry showed integrin αvß3 on the epithelium, the immune cells in Peyer's patches, the smooth muscle, and the endothelium of equine jejuna. In equine lungs, we recognized integrin αvß3 on the endothelium of blood vessels, the alveolar septa, the bronchial lymph nodes, and the cartilages, although the expression of integrin αvß3 was weak on the epithelium of bronchioles. In conclusion, these are the first data to show the expression of integrin αvß3 in equine lungs and jejuna.

L'intégrine alpha-v/beta3 (αvß3) reconnaît les séquences arginine-glycine-acide aspartique (RGD) et a d'importantes fonctions dans l'adhésion cellulaire, la signalisation et la survie. Toutefois, l'expression de l'intégrine αvß3 dans les poumons et le jéjunum équins n'est pas bien comprise. L'objectif de la présente étude était d'explorer l'expression inconnue jusqu'à ce jour de l'intégrine αvß3 dans les poumons et le jéjunum du cheval en utilisant l'immunohistochimie photonique et électronique. L'immunohistochimie a montré l'intégrine αvß3 sur l'épithélium, les cellules immunitaires des plaques de Peyer, le muscle lisse et l'endothélium du jéjunum équin. Dans les poumons équins, nous avons reconnu l'intégrine αvß3 sur l'endothélium des vaisseaux sanguins, les septas alvéolaires, les noeuds lymphatique bronchiaux et les cartilages, quoique l'expression de l'intégrine αvß3 était faible sur l'épithélium des bronchioles. En conclusion, ceci représente les premiers résultats qui démontrent l'expression de l'intégrine αvß3 dans les poumons et le jéjunum équins.(Traduit par Docteur Serge Messier).

Leukocyte-specific protein 1 regulates neutrophil recruitment in acute lung inflammation.

The mechanisms of excessive migration of activated neutrophils into inflamed lungs, credited with tissue damage, are not fully understood. We explored the hitherto unknown expression of leukocyte-specific protein 1 (LSP1) in human and mouse lungs and neutrophils and examined its role in neutrophil migration in acute lung inflammation. Autopsied septic human lungs showed increased LSP1 labeling in epithelium, endothelium, and leukocytes, including in their nuclei compared with normal lungs. We induced acute lung inflammation through intranasal administration of E. coli lipopolysaccharide (LPS) (80 µg) in LSP1-deficient (Lsp1(-/-)) and wild-type (WT) 129/SvJ mice. Immunocytochemistry and Western blots showed increased expression of LSP1 and phosphorylated LSP1 in lungs of LPS-treated WT mice. Histology showed more congestion, inflammation, and Gr-1(+) neutrophils in lung of WT mice than Lsp1(-/-) mice. LPS-treated WT mice had significantly more neutrophils in bronchoalveolar lavage (BAL) and myeloperoxidase levels in lungs compared with Lsp1(-/-) mice. However, there were no differences in lung tissue and BAL concentrations of keratinocyte-derived chemokine, monocyte chemoattractant protein-1, macrophage inflammatory protein-1α and -1ß, vascular permeability, and phosphorylated p38 MAPK between LPS-treated WT and Lsp1(-/-) mice, whereas TNF-α concentration was higher in BAL fluid from LPS-treated WT. Immunoelectron microscopy showed increased LSP1 in the nuclei of LPS-treated neutrophils. We also found increased levels of phosphorylated LSP1 associated with plasma membrane, nucleus, and cytosol at various times after LPS treatment of murine bone marrow-derived neutrophils, suggesting its role in modulation of neutrophil cytoskeleton and the membrane. These data collectively show increased expression of LSP1 in inflamed mouse and human lungs and its role in neutrophil recruitment and lung inflammation.