Obesity is often marked by chronic, low-grade inflammation, which is believed to contribute to metabolic disturbances associated with this condition. Chih-Hao Lee and colleagues show that injection of a known immunomodulatory glycan, one found in mother's milk and in S. mansoni egg extract, results in improved metabolic function of the adipose tissue and liver in a mouse dietary-mediated obesity model. Parasitic worms express host-like glycans to attenuate the immune response of human hosts. The therapeutic potential of this immunomodulatory mechanism in controlling the metabolic dysfunction that is associated with chronic inflammation remains unexplored. We demonstrate here that administration of lacto-N-fucopentaose III (LNFPIII), a LewisX-containing immunomodulatory glycan found in human milk and on parasitic helminths, improves glucose tolerance and insulin sensitivity in diet-induced obese mice. This effect is mediated partly through increased interleukin-10 (Il-10) production by LNFPIII-activated macrophages and dendritic cells, which reduces white adipose tissue inflammation and sensitizes the insulin response of adipocytes. Concurrently, LNFPIII treatment upregulates nuclear receptor subfamily 1, group H, member 4 (Fxr-α, also known as Nr1h4) to suppress lipogenesis in the liver, conferring protection against hepatosteatosis. At the signaling level, the extracellular signal-regulated kinase (Erk)-activator protein 1 (Ap1) pathway seems to mediate the effects of LNFPIII on both inflammatory and metabolic pathways. Our results suggest that LNFPIII may provide new therapeutic approaches to treat metabolic diseases.

Vaccination remains the most effective public health tool to prevent infectious diseases. Many vaccines are marginally effective and need enhancement for immunocompromised, elderly, and very young populations. To enhance immunogenicity, we exploited the biphasic property of the (RADA)4 synthetic oligopeptide to create VacSIM (vaccine self-assembling immune matrix), a new delivery method. VacSIM solution can easily be mixed with antigens, organisms, and adjuvants for injection. Postinjection, the peptides self-assemble into hydrated nanofiber gel matrices, forming a depot with antigens and adjuvants in the aqueous phase. We believe the depot provides slow release of immunogens, leading to increased activation of antigen-presenting cells that then drive enhanced immunogenicity. Using recombinant hepatitis B virus surface antigen (rHBsAg) as a model immunogen, we compared VacSIM delivery to delivery in alum or complete Freund's adjuvant (CFA). Delivery of the rHBsAg antigen to mice via VacSIM without adjuvant elicited higher specific IgG responses than when rHBsAg was delivered in alum or CFA. Evaluating IgG subtypes showed a mixed Th1/Th2 type response following immunization with VacSIM, which was driven further toward Th1 with addition of CpG as the adjuvant. Increased specific IgG endpoint titers were observed in both C57BL/6 and BALB/c mice, representative of Th1 and Th2 environments, respectively. Restimulation of splenocytes suggests that VacSIM does not cause an immediate proinflammatory response in the host. Overall, these results suggest that VacSIM, as a new delivery method, has the potential to enhance immunogenicity and efficacy of numerous vaccines.

The milk pentasaccharide LNFPIII has therapeutic action for metabolic and autoimmune diseases and prolongs transplant survival in mice when presented as a neoglycoconjugate. Within LNFPIII is the Lewis^x trisaccharide, expressed by many helminth parasites. In humans, LNFPIII is found in human milk and also known as stage-specific embryonic antigen-1. LNFPIII-NGC drives alternative activation of macrophages and dendritic cells via NFκB activation in a TLR4 dependent mechanism. However, the connection between LNFPIII-NGC activation of APCs, TLR4 signaling and subsequent MAP kinase signaling leading to anti-inflammatory activation of APCs remains unknown. In this study we determined that the innate receptor CD14 was essential for LNFPIII-NGC induction of both ERK and NFkB activation in APCs. Induction of ERK activation by LNFPIII-NGC was completely dependent on CD14/TLR4-Ras-Raf1/TPL2-MEK axis in bone marrow derived dendritic cells (BMDCs). In addition, LNFPIII-NGC preferentially induced the production of Th2 “favoring” chemokines CCL22 and matrix metalloprotease protein-9 in a CD14 dependent manner in BMDCs. In contrast, LNFPIII-NGC induces significantly lower levels of Th1 “favoring” chemokines, MIP1α, MIP1β and MIP-2 compared to levels in LPS stimulated cells. Interestingly, NGC of the identical human milk sugar LNnT, minus the alpha 1–3 linked fucose, failed to activate APCs via TLR4/MD2/CD14 receptor complex, suggesting that the alpha 1–3 linked fucose in LNFPIII and not on LNnT, is required for this process. Using specific chemical inhibitors of the MAPK pathway, we found that LNFPIII-NGC induction of CCL22, MMP9 and IL-10 production was dependent on ERK activation. Over all, this study suggests that LNFPIII-NGC utilizes CD14/TLR4-MAPK (ERK) axis in modulating APC activation to produce anti-inflammatory chemokines and cytokines in a manner distinct from that seen for the pro-inflammatory PAMP LPS. These pathways may explain the in vivo therapeutic effect of LNFPIII-NGC treatment for inflammation based diseases.

The mechanism of alternative activation of antigen-presenting cells (APCs) is largely unknown. Lacto-N-fucopentaose III (LNFPIII) is a biologically conserved pentasaccharide that contains the Lewis^xtrisaccharide. LNFPIII conjugates and schistosome egg antigens, which contain the Lewis^xtrisaccharide, drive alternative activation of APCs and induce anti-inflammatory responsesin vivo, preventing inflammation-based diseases, including psoriasis, transplant organ rejection, and metabolic disease. In this study, we show that LNFPIII conjugates and schistosome egg antigens interact with APCs via a receptor-mediated process, requiring internalization of these molecules through a clathrin/dynamin-dependent but caveolus-independent endocytic pathway. Using inhibitors/small interfering RNA (siRNA) against dynamin and clathrin, we show for the first time that endocytosis of Lewis^x-containing glycans is required to drive alternative maturation of antigen-presenting cells and Th2 immune responses. We identified mouse SIGNR-1 as a cell surface receptor for LNFPIII conjugates. Elimination of SIGNR-1 showed no effect on uptake of LNFPIII conjugates, suggesting that other receptors bind to and facilitate uptake of LNFPIII conjugates. We demonstrate that disruption of actin filaments partially prevented the entry of LNFPIII conjugates into APCs and that LNFPIII colocalizes with both early and late endosomal markers and follows the classical endosomal pathway leading to lysosome maturation. The results of this study show that the ability of LNFPIII to induce alternative activation utilizes a receptor-mediated process that requires a dynamin-dependent endocytosis. Thus, key steps have been defined in the previously unknown mechanism of alternative activation that ultimately leads to induction of anti-inflammatory responses.