技术资料

Ab-targeted vaccination involves targeting a receptor of choice expressed by dendritic cells (DCs) with Ag-coupled Abs. Currently,there is little consensus as to which criteria determine receptor selection to ensure superior Ag presentation and immunity. In this study,we investigated parameters of DC receptor internalization and determined how they impact Ag presentation outcomes. First,using mixed bone marrow chimeras,we established that Ag-targeted,but not nontargeted,DCs are responsible for Ag presentation in settings of Ab-targeted vaccination in vivo. Next,we analyzed parameters of DEC205 (CD205),Clec9A,CD11c,CD11b,and CD40 endocytosis and obtained quantitative measurements of internalization speed,surface turnover,and delivered Ag load. Exploiting these parameters in MHC class I (MHC I) and MHC class II (MHC II) Ag presentation assays,we showed that receptor expression level,proportion of surface turnover,or speed of receptor internalization did not impact MHC I or MHC II Ag presentation efficiency. Furthermore,the Ag load delivered to DCs did not correlate with the efficiency of MHC I or MHC II Ag presentation. In contrast,targeting Ag to CD8(+) or CD8(-) DCs enhanced MHC I or MHC II Ag presentation,respectively. Therefore,receptor expression levels,speed of internalization,and/or the amount of Ag delivered can be excluded as major determinants that dictate Ag presentation efficiency in setting of Ab-targeted vaccination. View Publication

Enterovirus type 71 (EV71) and coxsackievirus A 16 (CA16) are the major pathogens of human hand,foot,and mouth disease (HFMD). In our previous study,intramuscular immunization with the inactivated EV71 vaccine elicited effective immunity,while immunization with the inactivated CA16 vaccine did not. In this report,we focused on innate immune responses elicited by inactivated EV71 and CA16 antigens administered intradermally or intramuscularly. The distributions of the EV71 and CA16 antigens administered intradermally or intramuscularly were not obviously different,but the antigens were detected for a shorter period of time when administered intradermally. The expression levels of NF-kappaB pathway signaling molecules,which were identified as being capable of activating DCs,ILCs,and T cells,were higher in the intradermal group than in the intramuscular group. Antibodies for the EV71 and CA16 antigens colocalized with ILCs and DCs in skin and muscle tissues under fluorescence microscopy. Interestingly,ILC colocalization decreased over time,while DC colocalization increased over time. ELISpot analysis showed that coordination between DCs and ILCs contributed to successful adaptive immunity against vaccine antigens in the skin. EV71 and/or CA16 antigen immunization via the intradermal route was more capable of significantly increasing neutralizing antibody titers and activating specific T cell responses than immunization via the intramuscular route. Furthermore,neonatal mice born to mothers immunized with the EV71 and CA16 antigens were 100{\%} protected against wild-type EV71 or CA16 viral challenge. Together,our results provide new insights into the development of vaccines for HFMD. View Publication

We investigated the contribution of host immune cells to bacterial killing in a whole-blood bactericidal activity (WBA) assay,an ex vivo model used to test efficacy of drugs against mycobacterium tuberculosis (Mtb). We performed WBA assays with immuno-magnetic depletion of specific cell types,in the presence or absence of rifampicin. Innate immune cells decreased Mtb growth in absence of drug,but appeared to diminish the cidal activity of rifampicin,possibly attributable to intracellular bacterial sequestration. Adaptive immune cells had no effect with or without drug. The WBA assay may have potential for testing adjunctive host-directed therapies acting on phagocytic cells. View Publication

BACKGROUND Atopy and viral respiratory tract infections synergistically promote asthma exacerbations. IgE cross-linking inhibits critical virus-induced IFN-α responses of plasmacytoid dendritic cells (pDCs),which can be deficient in patients with allergic asthma. OBJECTIVE We sought to determine whether reducing IgE levels in vivo with omalizumab treatment increases pDC antiviral IFN-α responses in inner-city children with asthma. METHODS PBMCs and pDCs isolated from children with exacerbation-prone asthma before and during omalizumab treatment were stimulated ex vivo with rhinovirus and influenza in the presence or absence of IgE cross-linking. IFN-α levels were measured in supernatants,and mRNA expression of IFN-α pathway genes was determined by using quantitative RT-PCR (qRT-PCR) in cell pellets. FcεRIα protein levels and mRNA expression were measured in unstimulated cells by using flow cytometry and qRT-PCR,respectively. Changes in these outcomes and associations with clinical outcomes were analyzed,and statistical modeling was used to identify risk factors for asthma exacerbations. RESULTS Omalizumab treatment increased rhinovirus- and influenza-induced PBMC and rhinovirus-induced pDC IFN-α responses in the presence of IgE cross-linking and reduced pDC surface FcεRIα expression. Omalizumab-induced reductions in pDC FcεRIα levels were significantly associated with a lower asthma exacerbation rate during the outcome period and correlated with increases in PBMC IFN-α responses. PBMC FcεRIα mRNA expression measured on study entry significantly improved an existing model of exacerbation prediction. CONCLUSIONS These findings indicate that omalizumab treatment augments pDC IFN-α responses and attenuates pDC FcεRIα protein expression and provide evidence that these effects are related. These results support a potential mechanism underlying clinical observations that allergic sensitization is associated with increased susceptibility to virus-induced asthma exacerbations. View Publication