Human carcinomas can metabolically incorporate and present the dietary non-human sialic acid Neu5Gc, which differs from the human sialic acid N-acetylneuraminic acid (Neu5Ac) by one oxygen atom. Tumor-associated Neu5Gc can interact with low levels of circulating anti-Neu5Gc antibodies, thereby facilitating tumor progression via chronic inflammation in a human-like Neu5Gc-deficient mouse model. Here we show that human anti-Neu5Gc antibodies can be affinity-purified in substantial amounts from clinically-approved intravenous IgG (IVIG) and used at higher concentrations to suppress growth of the same Neu5Gc-expressing tumors. Hypothesizing that this polyclonal spectrum of human anti-Neu5Gc antibodies also includes potential cancer biomarkers, we then characterize them in cancer and non-cancer patients’ sera, using a novel sialoglycan-microarray presenting multiple Neu5Gc-glycans and control Neu5Ac-glycans. Antibodies against Neu5Gcα2–6GalNAcα1-O-Ser/Thr (GcSTn) were found to be more prominent in patients with carcinomas than with other diseases. This unusual epitope arises from dietary Neu5Gc incorporation into the carcinoma marker Sialyl-Tn, and is the first example of such a novel mechanism for biomarker generation. Finally, human serum or purified antibodies rich in anti-GcSTn-reactivity kill GcSTn-expressing human tumors via complement-dependent-cytotoxicity or antibody-dependent-cellular-cytotoxicity. Such xeno-autoantibodies and xenoautoantigens have potential for novel diagnostics, prognostics and therapeutics in human carcinomas.

Flightless-I (fliI) is a novel member of the gelsolin family that is important for actin organization duringGelsolin is a Ca 2ϩ -and phosphatidylinositol 4,5-bisphosphate-regulated actin-binding protein (1). It has been implicated in the regulation of the actin cytoskeleton and the modulation of membrane-cytoskeletal cross-talks (2-4). Many gelsolin-like proteins have been identified and they appear to have evolved from an ancestral single segment gene that has duplicated multiple times to form proteins with 3-or 6-fold repeats (5). Recent three-dimensional structure analyses show that the segments within gelsolin (6), as well as segments from different gelsolin family members, have a similar core structure (7-9). Nevertheless, the gelsolin family of proteins have distinct actin binding characteristics and intracellular localizations. For example, unlike most gelsolin members, CapG is a nuclear as well as cytoplasmic protein (10) and it does not sever filaments (11). Therefore, the conserved residues in each protein appear to maintain the basic folds of the repeated segments, while actin binding per se involves residues customized for each segment and for each protein.Flightless I (fliI) 1 is a recently identified member of the gelsolin family (12). It was discovered as a mutation in Drosphila melanogaster that leads to flightlessness. This phenotype is accompanied by disorganization of the indirect flight muscle myofibrils (13). Other more severe fliI mutations lead to late larval or pupal death. Eggs lacking maternally supplied fliI show incomplete cellularization, abnormal furrow formation, and impaired gastrulation. Defective cellularization of the syncytial blastoderm is associated with a disorganized cortical actin cytoskeleton (14). The flightless and cellularization phenotypes suggest that fliI is required for actin organization during myogenesis and embryogenesis, respectively. The human flightless I (FLI) locus has been mapped to a region deleted in the Smith-Magenis syndrome (15), which is associated with a spectrum of developmental and behavioral abnormalities. The COOH-terminal half of human FLI has 31% identity and 52% similarity to human gelsolin (12), and has the same 6-fold segmental repeat typical of many gelsolin family members (Fig. 1A). Since FLI is more divergent from gelsolin than other gelsolin family members such as CapG, adseverin, and villin (1), it probably arose from the prototypical ancestral protein very early during phylogeny and evolved independently (16). Therefore, it is necessary to determine whether FLI is an actin-binding protein, and how it interacts with actin.The NH 2 -terminal half of FLI is distinct from that of the other previously identified gelsolin members. It contains 16 tandem 23-amino acid leucine-rich repeat motif (LRR) (12) (Fig. 1A) found in an emerging collection of proteins (17). Close

BackgroundAcne vulgaris afflicts more than fifty million people in the United State and the severity of this disorder is associated with the immune response to Propionibacterium acnes (P. acnes). Systemic therapies for acne target P. acnes using antibiotics, or target the follicle with retinoids such as isotretinoin. The latter systemic treatment is highly effective but also carries a risk of side effects including immune imbalance, hyperlipidemia, and teratogenicity. Despite substantial research into potential new therapies for this common disease, vaccines against acne vulgaris are not yet available.Methods and FindingsHere we create an acne vaccine targeting a cell wall-anchored sialidase of P. acnes. The importance of sialidase to disease pathogenesis is shown by treatment of a human sebocyte cell line with recombinant sialidase that increased susceptibility to P. acnes cytotoxicity and adhesion. Mice immunized with sialidase elicit a detectable antibody; the anti-sialidase serum effectively neutralized the cytotoxicity of P. acnes in vitro and P. acnes-induced interleukin-8 (IL-8) production in human sebocytes. Furthermore, the sialidase-immunized mice provided protective immunity against P. acnes in vivo as this treatment blocked an increase in ear thickness and release of pro-inflammatory macrophage inflammatory protein (MIP-2) cytokine.ConclusionsResults indicated that acne vaccines open novel therapeutic avenues for acne vulgaris and other P. acnes-associated diseases.

Propionibacterium acnes is a key pathogen involved in the progression of inflammation in acne vulgaris. We examined whether vaccination against P. acnes suppressed P. acnes-induced skin inflammation. Inactivation of P. acnes with heat was employed to create a P. acnes-based vaccine. Intranasal immunization in mice with this inactivated vaccine provoked specific antibodies against P. acnes. Most notably, immunization with inactivated vaccines generated in vivo protective immunity against P. acnes challenge and facilitated the resolution of ear inflammation in mice. In addition, antibodies elicited by inactivated vaccines effectively neutralized the cytotoxicity of P. acnes and attenuated the production of proinflammatory cytokine IL-8 in human sebocyte SZ95 cells. Intranasal immunization using heat-inactivated P. acnes-based vaccines provided a simple modality to develop acne vaccines. These observations highlight the concept that development of vaccines targeting microbial products may represent an alternative strategy to conventional antibiotic therapy.