Recent studies have demonstrated that therapies targeting the innate immune system have the potential to provide transient, non-specific protection from a variety of infectious organisms; however, the potential of enhancing the efficacy of such treatments using nano-scale delivery platforms requires more in depth evaluation. As such, we employed a nanolipoprotein (NLP) platform to enhance the efficacy of innate immune agonists. Here, we demonstrate that the synthetic Toll-like receptor (TLR) agonists monophosphoryl lipid A (MPLA) and CpG oligodeoxynucleotides (CpG) can be readily incorporated into NLPs. Conjugation of MPLA and CpG to NLPs (MPLA:NLP and CpG:NLP, respectively) significantly enhanced their immunostimulatory profiles both in vitro and in vivo compared to administration of agonists alone, as evidenced by significant increases in cytokine production, cell surface expression of activation markers, and upregulation of immunoregulatory genes. Importantly, enhancement of cytokine production by agonist conjugation to NLPs was also observed in primary human dendritic cells. Furthermore, BALB/c mice pretreated with CpG:NLP constructs survived a lethal influenza challenge whereas pretreatment with CpG alone had no effect on survival.

Chronic immune activation despite long-term therapy poses an obstacle to immune recovery in HIV infection. The role of antigen presenting cells (APCs) in chronic immune activation during HIV infection remains to be fully determined. APCs, the frontline of immune defense against pathogens, are capable of distinguishing between pathogens and non-pathogenic, commensal bacteria. We hypothesized that HIV infection induces dysfunction in APC immune recognition and response to some commensal bacteria and that this may promote chronic immune activation. Therefore we examined APC inflammatory cytokine responses to commensal lactobacilli. We found that APCs from HIV-infected patients produced an enhanced inflammatory response to Lactobacillus plantarum WCFS1 as compared to APCs from healthy, HIV-negative controls. Increased APC expression of TLR2 and CD36, signaling through p38-MAPK, and decreased expression of MAP kinase phosphatase-1 (MKP-1) in HIV infection was associated with this heightened immune response. Our findings suggest that chronic HIV infection enhances the responsiveness of APCs to commensal lactobacilli, a mechanism that may partly contribute to chronic immune activation.