| Parasitic infections regulate/alter the host immune response. Helminth infections, such as Schistosoma mansoni, induce immunosuppressive and Type 2 immunity which causes CD4+ T helper (Th) 2 cell differentiation. S. mansoni immunoregulation research focuses on secreted molecules, namely secreted glycans such as Lacto-N-fucopentaose III (LNFPIII) and Lewis X. The LNFPIII/LewisX glycans drive Type 2 immunity complete with in vivo IgE production, eosinophil recruitment, and alternative activated macrophage maturation. However, little has been revealed on the in vitro signaling behaviors of LNPFIII/Lewis X. Within this thesis, we will explore the upstream and downstream signaling behaviors of LNFPIII in macrophages in comparison to the Type 1 immunomodulator Lipopolysaccharide (LPS), a pathogen associated molecular pattern from gram negative bacterium. The signaling behavior of LPS is well documented. LPS, like LNFPIII, interact with Toll Like Receptor 4 (TLR4) within a complex lipid raft structure on the plasma membrane surface. The LPS intracellular signaling cascade involves recruitment of the TIR adaptors MyD88/TRIF, which ultimately leads to MAPK activation and NFkappaB translocation, which drives CD4+ Th1 cell differentiation. In contrast, LNFPIII activation promotes MAPK Erk and NFkB translocation to drive CD4+ Th2 cell differentiation. We compared LNFPIII and LPS signaling, using Affymetrix Genome Mouse Arrays and SuperArray Oligonucleotide Arrays, as well as Rule Based Medicine Analyte Arrays to identify a unique gene expression and protein production profile for LNFPIII in comparison to LPS. LNFPIII has an intermediate expression profile that is less robust in comparison to LPS. Through Ingenuity Pathway Analysis of gene expression, the involvement of potential Type 2 immune responders Erk and NFkappaB were confirmed in LNFPIII signaling, in addition to Raf, RasGRF1, Syk, and Trib1. Furthermore, the upstream Src-Raf-Erk signaling cascade was identified to be independent of downstream NFkappaB activation in LNFPIII and LPS induced signaling. LNFPIII induced NFkappaB activation was found to be TLR4/MyD88-dependent and TLR2/TRIF-independent. Recent studies have identified that LPS induced TRIF signaling is endosome-dependent; however, our studies demonstrate that LNFPIII induced gene expression and NFkappaB activation is partially endosome dependent. Overall, LNFPIII induces a unique signaling repertoire that mediates an immunosuppressant host immune response. |
