%0 Generic
%9 Doctoral Dissertation
%A Zaccard, Colleen R.
%D 2015
%F pittir:24493
%K dendritic cells, CD40L, tunneling nanotubes, Th1 cells, inflammation, reticulation, HIV-1, trans-infection, intercellular communication
%T Tunneling nanotube networks in dendritic cell communication and HIV-1 trans-infection
%U http://d-scholarship-dev.library.pitt.edu/24493/
%X The ability of dendritic cells (DC) to mediate CD4+ T cell help for cellular immunity is guided by instructive signals received during maturation, and the resulting pattern of DC responsiveness to the Th signal, CD40L.  Furthermore, the professional transfer of antigenic information from migratory to lymph node-residing DC is critical for the effective induction of cellular immune responses.  Here we report that, in addition to their enhanced IL-12p70 producing capacity, human DC matured in the presence of inflammatory mediators of type-1 immunity (DC1) are uniquely programmed to develop networks of tunneling nanotubes (TNTs) in response to CD40L-expressing CD4+ Th cells or recombinant CD40L.  This immunologic process of ‘reticulation’ facilitates intercellular trafficking of endosome-associated vesicles and antigen, and is regulated by the opposing roles of IFN-g and IL-4.  The initiation of reticulation represents a novel helper function of CD40L and a superior mechanism of intercellular communication possessed by DC1, as well as a pathway for exploitation by pathogens for direct cell-cell spread.  Importantly, DC1 possess a superior ability to transmit HIV-1 to CD4+ T cells compared to DC2.  DC1 highly express Siglec-1, the lectin associated with HIV-1 capture by mature DC, while DC2 fail to do so, indicating differential ability of polarized DC to acquire virus.  Furthermore, CD40L signaling is critical for DC1-mediated HIV-1 trans-infection, as demonstrated by the abolition of transmission upon treatment with CD40L-specific blocking antibody.  TNT formation is dependent on F-actin and cholesterol-rich lipid rafts, as DC1 trans-infection was abrogated by pre-treatment with latrunculin A or simvastatin, which depolymerize actin or inhibit cholesterol synthesis, respectively, at concentrations that also inhibited TNT networks.  Additionally, HIV-1-like-particle-pulsed DC1 were co-cultured with CD4+ T cells in the setting of reticulation, and live-cell super-resolution imaging revealed strong supporting evidence for TNT-mediated HIV-1 transmission.  Finally, high ICAM-1 surface expression was previously linked to enhanced DC1 trans-infection, and we visualized ICAM-1 puncti localization to TNTs.  These data demonstrate a role for reticulation in DC1-driven HIV-1 trans-infection in addition to its immunologic function, which impacts public health by providing a rationale for exploration of therapeutic strategies to target this process and interrupt HIV-1 transmission.