Autophagy facilitates antibody-enhanced dengue virus infection in human pre-basophil/mast cells.

BACKGROUND: Dengue virus (DENV) infection can cause severe hemorrhagic disease in humans. Although the pathogenic mechanisms underlying severe DENV disease remain unclear, one of the possible contributing factors is antibody-dependent enhancement (ADE) which occurs when sub-neutralizing antibodies derived from a previous DENV infection enhance viral infection through interaction between virus-antibody complexes and FcR-bearing cells, such as macrophages and basophil/mast cells. Although recent reports showed that DENV induces autophagy, the relationship between antibody-enhanced DENV infection and autophagy is not clear. METHODOLOGY/PRINCIPAL FINDINGS: We showed that sub-neutralizing antibodies derived from dengue patient sera enhanced DENV infection and autophagy in the KU812 pre-basophil-like cell line as well as the HMC-1 immature mast cell line. Antibody-enhanced DENV infection of KU812 cells increased the number of autophagosome vesicles, LC3 punctation, LC3-II accumulation, and p62 degradation over that seen in cells infected with DENV alone. The percentages of DENV envelope (E) protein-positive cells and LC3 puncta following antibody-enhanced DENV infection of KU812 cells were reduced by the autophagy inhibitor 3-MA. Antibody-enhanced DENV infection of HMC-1 cells showed co-localization of DENV E protein and dsRNA with autophagosomes, which was inhibited by 3-MA treatment. Furthermore, DENV infection and replication were reduced when KU812 cells were transfected with the autophagy-inhibiting Atg4BC74A mutant. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate a significant induction of autophagy in antibody-enhanced DENV infection of pre-basophil-like KU812 and immature mast cell-like HMC-1 cells. Also, autophagy plays an important role in DENV infection and replication in these cells. Given the importance of ADE and FcR-bearing cells such as monocytes, macrophages and basophil/mast cells in dengue disease, the results provide insights into dengue pathogenesis and therapeutic means of control.

Protection against dengue virus infection in mice by administration of antibodies against modified nonstructural protein 1.

BACKGROUND: Infection with dengue virus (DENV) may cause life-threatening disease with thrombocytopenia and vascular leakage which are related to dysfunction of platelets and endothelial cells. We previously showed that antibodies (Abs) against DENV nonstructural protein 1 (NS1) cross-react with human platelets and endothelial cells, leading to functional disturbances. Based on sequence homology analysis, the C-terminal region of DENV NS1 protein contains cross-reactive epitopes. For safety in vaccine development, the cross-reactive epitopes of DENV NS1 protein should be deleted or modified. METHODOLOGY/PRINCIPAL FINDINGS: We tested the protective effects of Abs against full-length DENV NS1, NS1 lacking the C-terminal amino acids (a.a.) 271-352 (designated ΔC NS1), and chimeric DJ NS1 consisting of N-terminal DENV NS1 (a.a. 1-270) and C-terminal Japanese encephalitis virus NS1 (a.a. 271-352). The anti-ΔC NS1 and anti-DJ NS1 Abs showed a lower binding activity to endothelial cells and platelets than that of anti-DENV NS1 Abs. Passive immunization with anti-ΔC NS1 and anti-DJ NS1 Abs reduced DENV-induced prolonged mouse tail bleeding time. Treatment with anti-DENV NS1, anti-ΔC NS1 and anti-DJ NS1 Abs reduced local skin hemorrhage, controlled the viral load of DENV infection in vivo, synergized with complement to inhibit viral replication in vitro, as well as abolished DENV-induced macrophage infiltration to the site of skin inoculation. Moreover, active immunization with modified NS1 protein, but not with unmodified DENV NS1 protein, reduced DENV-induced prolonged bleeding time, local skin hemorrhage, and viral load. CONCLUSIONS/SIGNIFICANCE: These results support the idea that modified NS1 proteins may represent an improved strategy for safe and effective vaccine development against DENV infection.

Endothelial cell surface expression of protein disulfide isomerase activates ß1 and ß3 integrins and facilitates dengue virus infection.

Infection with dengue virus (DENV) causes diseases ranging from mild dengue fever to severe hemorrhage or shock syndrome. DENV infection of endothelial cells may cause cell apoptosis or vascular leakage and result in clinical illness of hemorrhage. However, the endothelial cell molecules involved in DENV infection and the mechanisms governing virus-cell interactions are still uncertain. Since protein disulfide isomerase (PDI) reducing function at the cell surface was shown to be required for entry of certain viruses and bacteria, we explored the role of PDI expressed on endothelial cell surface in DENV infection. Using siRNA to knock down PDI, DENV infection was reduced which could be reversed by treating cells with a reducing agent Tris(2-carboxyethyl)phosphine hydrochloride (TCEP). DENV-induced PDI surface expression was mediated through the Lys-Asp-Glu-Leu (KDEL) receptor-Src family kinase signal pathway. Furthermore, cell surface PDI colocalized with ß1 and ß3 integrins after DENV infection, and the activation of integrins was blocked by PDI inhibition. Finally, blockade of PDI inhibited DENV entry into endothelial cells. Our findings suggest a novel mechanism whereby surface PDI which causes integrin activation is involved in DENV entry, and DENV infection further increases PDI surface expression at later time points. These findings may have implications for anti-DENV drug design.

Psychological profile of Taiwanese female cosmetic surgery candidates: understanding their motivation for cosmetic surgery.

BACKGROUND: Psychological processes consisting of body image and self-esteem are considered key to the motivation for cosmetic surgery (CS). The current study aimed to investigate such processes as well as social support, perception of other people's opinion, and sex life satisfaction of Taiwanese female CS candidates. Further analyses were conducted to identify which processes predicted motivation for CS. METHOD: Questionnaires comprising subscales of the Multidimensional Body-Self Relations Questionnaire, the Rosenberg Self-Esteem Scale, the Perception of Other Peoples' Opinion Scale, and social support and sex life questions were completed by Taiwanese female CS candidates (n = 85) preoperatively. The results were compared with those for a sex-matched nonsurgical control group (n = 105) as well as previously published data and reference norms. Correlation and multiple regression analysis also was conducted to identify any relationship between variables as well as which variable best predicted the likelihood of a patient having surgery. RESULTS: A total of 29 CS candidates (34.1%) reported before their surgical consultation that they would "very likely" or "likely" have CS, and 54 (63.5%) received support from all three social groups, namely, family, friends, and partner. The body image (appearance evaluation, orientation, and body area satisfaction) of the CS candidates was not significantly different from that of the control group. The former had significantly higher self-esteem and perception of other people's opinion scores. Self-esteem was positively correlated with appearance evaluation (r = 0.484; p < 0.01) and body area satisfaction (r = 0.494; p < 0.01). Body area satisfaction had a fair degree of negative correlation with the likelihood of having CS (r = -0.413; p < 0.01). Regression analysis indicated that only body area dissatisfaction predicted the likelihood of having CS, accounting for 29.4% of the total variance. CONCLUSIONS: The results of this study indicate that the Taiwanese female CS candidates did not have higher body image dissatisfaction or greater body image investment than the control group. However, body area dissatisfaction was the only significant predictor for the likelihood of having CS, a feature not previously recognized in Asian CS candidates. The higher self-esteem of the CS candidates opposes the view that low self-esteem is a principal motivating factor for CS.