Sex-based differences in respiratory disease outcomes are well recognized. However, the underlying immunological mechanisms driving this dimorphism remain incompletely understood. While sex hormones influence immune cell development and function, the role of commensal microbes in shaping sex-specific lung immunity has not been explored. Here, we used single-cell RNA sequencing (scRNAseq) and flow cytometry to profile lung immune cells in male and female mice housed under specific pathogen-free (SPF) or germ-free (GF) conditions. Under SPF conditions, males exhibited a striking myeloid bias, with increased monocytes and macrophages, along with broad upregulation of inflammatory mediators, including S100a8, S100a9, and Il1b, across multiple cell types, and enrichment of TNF and interferon (IFN) signaling pathways. In contrast, females displayed lymphocyte-skewed profiles, with higher frequencies of T cells and natural killer (NK) cells. Interestingly, these sex-based differences in immune composition and inflammatory programs were largely absent in GF mice, indicating that microbial exposure amplifies baseline immunological dimorphism between males and females. Notably, select sex-associated features, including female-biased NK cell enrichment, persisted irrespective of microbial status, suggesting intrinsic, microbiota-independent programming. Together, these findings indicate that commensal microbes modulate sex-specific lung immunity by amplifying pre-existing intrinsic differences, highlighting the intersection of extrinsic (microbial) and intrinsic (sex-linked) factors in shaping baseline mucosal immunity.

Sex-based differences in respiratory disease outcomes are well recognized. However, the underlying immunological mechanisms driving this dimorphism remain incompletely understood. While sex hormones influence immune cell development and function, the role of commensal microbes in shaping sex-specific lung immunity has not been explored. Here, we used single-cell RNA sequencing (scRNAseq) and flow cytometry to profile lung immune cells in male and female mice housed under specific pathogen-free (SPF) or germ-free (GF) conditions. Under SPF conditions, males exhibited a striking myeloid bias, with increased monocytes and macrophages, along with broad upregulation of inflammatory mediators, including S100a8, S100a9, and Il1b, across multiple cell types, and enrichment of TNF and interferon (IFN) signaling pathways. In contrast, females displayed lymphocyte-skewed profiles, with higher frequencies of T cells, B cells, and natural killer (NK) cells. Interestingly, these sex-based differences in immune composition and inflammatory programs were largely absent in GF mice, suggesting that microbial exposure influences baseline immunological dimorphism between males and females. Notably, select sex-associated immune differences, including female-biased NK cell enrichment, persisted irrespective of microbial status, suggesting intrinsic, microbiota-independent programming. Together, these findings indicate that commensal microbes may modulate sex-specific lung immunity, potentially amplifying pre-existing intrinsic differences, highlighting the intersection of extrinsic (microbial) and intrinsic (sex-linked) factors in shaping baseline mucosal immunity.

Vaccination with Klebsiella pneumoniae OmpX and the Th17 adjuvant LTA1 elicits lung CD4+ tissue-resident memory (TRM) Th17 cells that provide serotype-independent protection against K. pneumoniae, but vaccine efficacy declines as TRM numbers wane. To define the mechanisms sustaining these cells, we developed an ovalbumin (OVA) model with tetramer enrichment to track antigen-specific CD4+ TRM cells over time. Serial single-cell RNA sequencing on days 30, 90, and 184 after LTA1/OVA immunization revealed persistent glycolytic signatures across all time points, while ornithine decarboxylase 1 (Odc1), although required for Th17 differentiation in vitro, was dispensable for TRM maintenance in vivo. Inhibition of glycolysis with 2-deoxy-D-glucose impaired IL-17A production both in vivo and in precision-cut lung slice (PCLS) cultures which preserve functional TRM cells ex vivo. These findings identify glycolysis as a key metabolic pathway sustaining lung CD4+ Th17 TRM effector function and highlight PCLS as an ex vivo model.

The adjuvant effects of saponins, derived from the South American tree Quilaja Saponaria, are currently included in several injected vaccines. LT(R192G/L211A), or dmLT has been developed based on over 35 years of research on the use of bacterial ADP-ribosylating enterotoxins as adjuvants, including injected and oral delivery in Phase 1 and 2 clinical trials. While both adjuvants have been pursued independently, they have not been pursued together. Here, we explored combinations of saponin and dmLT adjuvant (SDA) for oral and sublingual delivery. First, we tested SDA combinations in a monocyte cell line (THP-1) to identify specific ratios with optimal activation of antigen presentation by upregulation of surface markers (MHC-II, CD86, CD40) and cytokine secretion (IL-1 beta, IFN-gamma). Next, we explored dosing combinations for evidence of vesicle structures by cyro-electron microscopy. Lastly, we identified that sublingual vaccination with SDA and protein antigen achieved equivalent or better antibody responses than an intramuscular injection. This is the first combination adjuvant designed for oral delivery to achieve all the benefits of mucosal, needle-free vaccination without issues of poor systemic immunity Supported by NIH/NIAID contract # 75N93023C00045 and R01AI166682-01 Vaccines and Immunotherapy (VAC)

Toll-like receptor 7 (Tlr7) deficiency-accelerated severe COVID-19 is associated with reduced production of interferons (IFNs). However, the underlying mechanisms remain elusive. To address these questions, we utilize Tlr7 and Irf7 deficiency mice, single-cell RNA analysis together with bone marrow transplantation approaches. We demonstrate that at the early phase of infection, SARS-CoV-2 causes the upregulation of Tlr7, Irf7, and IFN pathways in the lungs of the infected mice. The deficiency of Tlr7 and Irf7 globally and/or in immune cells in mice increases the severity of COVID-19 via impaired IFN activation in both immune and/or non-immune cells, leading to increased lung viral loads. These effects are associated with reduced IFN alpha and gamma levels in the circulation. The deficiency of Tlr7 tends to cause the reduced production and nuclear translocation of interferon regulatory factor 7 (IRF7) in the lungs of the infected mice, indicative of reduced IRF7 activation. Despite higher amounts of lung viral antigen, Tlr7 or Irf7 deficiency resulted in substantially reduced production of antibodies against SARS-CoV-2, thereby delaying the viral clearance. These results highlight the importance of the activation of TLR7 and IRF7 leading to IFN production on the development of innate and adaptive immunity against COVID-19.

Lung tissue resident memory (TRM) cells are thought to play crucial roles in lung host defense. We have recently shown that immunization with the adjuvant LTA1 (derived from the A1 domain of E. coli heat labile toxin) admixed with OmpX from K. pneumoniae can elicit antigen specific lung Th17 TRM cells that provide serotype independent immunity to members of the Enterobacteriaceae family. However, the upstream requirements to generate these cells are unclear. Single-cell RNA-seq showed that vaccine-elicited Th17 TRM cells expressed high levels of IL-1R1, suggesting that IL-1 family members may be critical to generate these cells. Using a combination of genetic and antibody neutralization approaches, we show that Th17 TRM cells can be generated independent of caspase-1 but are compromised when IL-1α is neutralized. Moreover IL-1α could serve as a molecular adjuvant to generate lung Th17 TRM cells independent of LTA1. Taken together, these data suggest that IL-1α plays a major role in vaccine-mediated lung Th17 TRM generation.

Rationale: To identify barriers and opportunities for Ph.D., basic and translational scientists to be fully integrated into clinical units. Objectives: In 2022, an ad hoc committee of the American Thoracic Society developed a project proposal and workshop to identify opportunities and barriers for scientists who do not practice medicine to develop successful careers and achieve tenure-track faculty positions in clinical departments and divisions within academic medical centers (AMCs) in the United States. Methods: This document focuses on results from a survey of adult and pediatric pulmonary, critical care, and sleep medicine division chiefs as well as a survey of workshop participants, including faculty in departmental and school leadership roles in both basic science and clinical units within U.S. AMCs. Results: We conclude that full integration of non-clinically practicing basic and translational scientists into the clinical units, in addition to their traditional placements in basic science units, best serves the tripartite mission of AMCs to provide care, perform research, and educate the next generation. Evidence suggests clinical units do employ Ph.D. scientists in large numbers, but these faculty are often hired into non-tenure track positions, which do not provide the salary support, start-up funds, research independence, or space often associated with hiring in basic science units within the same institution. These barriers to success of Ph.D. faculty in clinical units are largely financial. Conclusions: Our recommendation is for AMCs to consider and explore some of our proposed strategies to accomplish the goal of integrating basic and translational scientists into clinical units in a meaningful way.

Pneumocystis is the most common fungal pulmonary infection in children under the age of 5 years. In children with primary immunodeficiency, Pneumocystis often presents at 3–6 months of age, a time period that coincides with the nadir of maternal IgG and when IgM is the dominant Ig isotype. Because B cells are the dominant antigen-presenting cells for Pneumocystis, we hypothesized the presence of fungal-specific IgMs in humans and mice and that these IgM specificities would predict T cell antigens. We detected fungal-specific IgMs in human and mouse sera and utilized immunoprecipitation to determine whether any antigens were similar across donors. We then assessed T cell responses to these antigens and found anti-Pneumocystis IgM in WT mice, Aicda–/– mice, and in human cord blood. Immunoprecipitation of Pneumocystis murina with human cord blood identified shared antigens among these donors. Using class II MHC binding prediction, we designed peptides with these antigens and identified robust peptide-specific lung T cell responses after P. murina infection. After mice were immunized with 2 of the antigens, adoptive transfer of vaccine-elicited CD4+ T cells showed effector activity, suggesting that these antigens contain protective Pneumocystis epitopes. These data support the notion that germline-encoded IgM B cell receptors are critical in antigen presentation and T cell priming in early Pneumocystis infection.

Abstract With mortality rates ranging from 30% to 70%, carbapenem-resistant Klebsiella pneumoniae (Kp) is a significant public health threat. With growing incidence of drug resistance, it is imperative to develop alternative strategies to combat these severe infections. One novel immunotherapy is adoptive T cell transfer therapy using T cells genetically modified to express a T cell receptor (TCR) specific to an antigen of interest. Though successful against cancers and viral infections, this strategy has yet to be utilized for bacterial infections. Our study’s objective was to validate adoptive transfer as an immunotherapy against Kp infections using CD4 T cells from immunized mice. Further, we sought to identify TCRs specific to Kp epitopes for the generation of engineered Kp specific T cells. CD45.1 WT mice were intratracheally vaccinated with outer membrane protein X (OmpX) adjuvanted with heat-labile enterotoxin A1 twice at three weeks apart. Lung and splenic CD4 T cells from immunized mice were transferred into CD45.2 WT mice, followed by a challenge with Kp ST258 C4 strain. Immunized CD4 T cells were sequenced by single cell TCRseq to identify Kp specific TCR sequences. OmpX immunization resulted in a robust population of Kp specific Th17 cells in the lungs. Adoptive transfer of lung, but not splenic T cells from immunized mice significantly reduced bacterial burdens in challenged mice. Additionally, we identified 7 enriched TCR sequences that may be Omp specific. We have confirmed the efficacy of adoptive T cell transfer therapy against Kp infections using T cells from immunized mice. Moving forward we will validate our TCR sequences as Kp specific to genetically engineer both primary and cell line T cells for future therapeutic studies.

Tissue-resident memory (TRM) cells are thought to play a role in lung mucosal immunity to pathogens, but strategies to elicit TRM by mucosal vaccines have not yet been fully realized. Here, we formulated a vaccine composed of outer membrane protein (Omp) X from Klebsiella pneumoniae and LTA1 adjuvant that was administered by the intrapulmonary route. This vaccine elicited both TH1 and TH17 cells that shared transcriptional features with cells elicited by heat-killed K. pneumoniae. Antibody responses were required to prevent bacterial dissemination but dispensable for lung-specific immunity. In contrast, lung immunity required CD4+ T cells, STAT3 expression, and IL-17R signaling in fibroblasts. Lung-specific CD4+ T cells from OmpX+LTA1–immunized mice were observed homing to the lung and could mediate protection against infection in an adoptive transfer model. Vaccine-elicited TH17 cells showed reduced plasticity and were resistant to the immunosuppressant FK506 compared with TH1 cells, and TH17 cells conferred protection under conditions of transplant immunosuppression. These data demonstrate a promising vaccine strategy that elicits lung TRM cells and promotes serotype-independent immunity to K. pneumoniae.

Lower respiratory infections are among the leading causes of morbidity and mortality worldwide. These potentially deadly infections are further exacerbated due to the growing incidence of antimicrobial resistance. To combat these infections there is a need to better understand immune mechanisms that promote microbial clearance. This need in the context of lung infections has been further heightened with the emergence of SARS-CoV-2. Group 3 innate lymphoid cells (ILC3s) are a recently discovered tissue resident innate immune cell found at mucosal sites that respond rapidly in the event of an infection. ILC3s have clear roles in regulating mucosal immunity and tissue homeostasis in the intestine, though the immunological functions in lungs remain unclear. It has been demonstrated in both viral and bacterial pneumonia that stimulated ILC3s secrete the cytokines IL-17 and IL-22 to promote both microbial clearance as well as tissue repair. In this review, we will evaluate regulation of ILC3s during inflammation and discuss recent studies that examine ILC3 function in the context of both bacterial and viral pulmonary infections.

Chronic obstructive pulmonary disease (COPD) is characterized by elevated concentrations of inflammatory cytokines and chronic lung inflammation (1). Tobacco use is a primary cause of COPD (2), though mechanisms leading to disease development remain unknown. Although management of COPD is possible, most patients will experience at least one exacerbation each year, representing a large burden on the healthcare system (2). Therefore, studies into mechanisms leading to COPD could highlight targets for immunotherapeutic development, helping to decrease the burden of this disease. Cigarette smoke has been shown to elicit the production of several inflammatory cytokines in bronchial epithelial cells, including the understudied IL-36 family, implicating these cytokines as potential players in smokinginduced chronic inflammation that could lead to COPD (3). To explore this possibility, in this issue of the Journal, Kovach and colleagues (pp. 173–182) report on their investigations into the relationship between IL-36 cytokine expression and lung inflammation in long-term smokers with and without COPD (4). Discovered two decades ago, the IL-36 cytokines belong to the IL-1 superfamily and consist of three agonists—IL-36a, IL-36b, and IL-36g—and the IL-36 receptor antagonist (IL-36Ra) (5). IL-36 agonists promote inflammation via IL-36R signaling (6), and they function primarily at barrier sites, including the skin, lung, and gut, where they can sufficiently initiate immune protection mechanisms against environmental challenges (7). Signaling through IL-36R results in MyD88-dependent activation of proinflammatory pathways leading to recruitment and activation of immune cells as well as antimicrobial activity (8). Importantly, IL-36 agonists also stimulate T cells and dendritic cells in the skin (9) and induce T-cell proliferation and polarization (10), suggesting that these cytokines serve as a bridge between the innate and adaptive immune systems. The inflammatory signals induced by IL-36 agonists are regulated by IL-36Ra, helping to maintain tissue homeostasis (11, 12). However, disruption of this balance is a hallmark of several inflammatory diseases, including psoriasis, inflammatory bowel disease, and arthritis (13). Given the role of IL-36 in inflammatory diseases, it is reasonable to expect that the dysregulation of IL-36 signaling could significantly contribute to smoking-induced COPD progression. Although studies have shown that both IL-36a and IL-36g exert proinflammatory effects in the lung (14–16) and are elevated upon infection with viruses or bacteria in vivo (17, 18), little is known about the role of IL-36 in long-term inflammation in the lung. Using cells isolated from wild-type mouse lungs, Kovach and colleagues first determined cell-specific production of IL-36 agonists. After stimulation with heat-killed Klebsiella pneumoniae, differential expression of IL-36 was observed, in which fibroblasts and macrophages displayed increased IL-36g expression and type II alveolar epithelial cells displayed increased IL-36a expression. To determine whether cigarette smoke could induce IL-36 agonist expression in human lung cells, primary bronchial epithelial cells from nonsmokers were treated with cigarette smoke components for up to 7 days. Interestingly, temporal differences in IL-36 agonist expression were observed, such that IL-36g was upregulated early before declining in expression, whereas IL-36a was upregulated later at Day 7. These results suggest a role for IL-36g in mediating an early innate immune response whereas IL-36a may contribute more to chronic inflammation in the context of cigarette smoke component stimulation. Knowing that cells in both mouse and human lungs are responsive to elements leading to COPD, the authors next investigated patient plasma and BAL fluid (BALF) samples collected from long-term smokers (LTS) with or without COPD. Generally, systemic IL-36a and IL-36g expression was found to be higher in LTS with or without COPD compared with nonsmoker control subjects. The exception to this was that little difference was observed between concentrations of IL-36g in plasma from LTS with COPD compared with nonsmokers, which could support the idea that IL-36g is elevated early in the immune response, serving a protective role. In addition, both IL-36a and IL-36g were elevated locally in LTS with and without COPD compared with nonsmokers, with a trend toward higher concentrations of IL-36 agonists in BALF from patients with COPD compared with BALF from patients without COPD, though this was not statistically significant. An intriguing discovery came upon the observation that IL-36a protein concentrations in BALF were found to correlate with declining lung function as measured by forced expiratory volume in 1 second and airway obstruction as measured by the forced expiratory volume in 1 second/forced vital capacity ratio, suggesting that IL-36a could be a potential diagnostic marker for worsening lung function in COPD. To further investigate IL-36 agonists in the inflammatory cytokine milieu, correlations between a panel of Th1 and Th17 cytokines and IL-36g and IL-36a were examined in BALF and plasma samples. Several positive correlations were found both locally and systemically, supporting the notion that elevated IL-36 agonist concentrations are associated with an elevated inflammatory response. Further investigation of immune cell responses to direct stimulation with IL-36 agonists using

Infections due to carbapenem-resistant Klebsiella pneumoniae have emerged as a global threat due to its widespread antimicrobial resistance. Transplant recipients and patients with hematologic malignancies have high mortality rate, suggesting host factors in susceptibility. We developed a model of pulmonary infection using ST258 strain C4, KPC-2 clone, which are predominant K. pneumoniae carbapenemase-producing (KPC-producing) bacteria, and demonstrated that Rag2-/- Il2rg-/- mice - but not WT C57BL/6 or Rag2-/- mice - were susceptible to this opportunistic infection. Using single cell RNA sequencing in infected Rag2-/- mice, we identified distinct clusters of Ifng+ NK cells and Il17a+, Il22+, and inducible T cell costimulatory molecule-positive (ICOS+) group 3 innate lymphoid cells (ILCs) that were critical for host resistance. As solid organ transplantation is a risk factor, we generated a more clinically relevant model using FK506 in WT C57BL/6 mice. We further demonstrated that immunotherapy with recombinant IL-22 treatment ameliorated the ST258 pulmonary infection in both FK506-treated WT mice and Rag2-/- Il2rg-/- mice via hepatic IL-22ra1 signaling. These data support the development of host-directed immunotherapy as an adjunct treatment to new antibiotics.

Cells, both eukaryotic and prokaryotic, are covered with complex and diverse glycoconjugates that dictate interactions with the environment. In addition, intracellular glycoconjugates play key roles in intracellular signaling. Methods to selectively label, image, and purify glycoconjugates are critical to understanding their biological functions. The challenge of specifically tagging glycoconjugates is compounded by the fact that these biopolymers are not primary gene products, and therefore not amenable to genetic tagging. Thus, methods to chemoselectively address specific glycoconjugates are essential tools for studying glycoconjugate localization and behavior. This chapter begins with a brief introduction to the diversity of eukaryotic glycosylation. This is followed by discussion of chemoselective and chemoenzymatic labeling reactions that take advantage of the endogenous reactivity of native carbohydrate structures to achieve selective labeling of specific glycoconjugate classes. Next, we describe the use of metabolic oligosaccharide engineering using unnatural sugar precursors to introduce non-native functionalities that can be used for chemoselective labeling reactions, thereby achieving selective labeling of eukaryotic glycoconjugates. We also discuss how mutually orthogonal bioorthogonal reactions can be used in a combinatorial fashion to label distinct glycoconjugates. While the majority of the chapter focuses on eukaryotic glycoconjugates, the final section highlights examples of the application of chemoselective labeling reactions to bacterial glycoconjugates, an exciting emerging area of research. These examples demonstrate that chemoselective labeling reactions are an enabling technology that is facilitating multiple aspects of glycoscience research.

Sialic-acid-mediated interactions play critical roles on the cell surface, providing an impetus for the development of methods to study this important monosaccharide. In particular, photo-cross-linking sialic acids incorporated onto cell surfaces have allowed covalent capture of transient interactions between sialic acids and sialic-acid-recognizing proteins via cross-linking. However, natural sialic acids also present on the cell surface compete with photo-cross-linking sialic acids in binding events, limiting cross-linking yields. In order to improve the utility of one such photo-cross-linking sialic acid, SiaDAz, we examined a number of sialidases, enzymes that remove sialic acids from glycoconjugates, to find one that would cleave natural sialic acids but remain inactive toward SiaDAz. Using this sialidase, we improved SiaDAz-mediated cross-linking of an antisialyl Lewis X antibody and of endoglin. This protocol can be applied generally to sialic-acid-mediated interactions and will facilitate identification of sialic acid binding partners.

Neuraminidases hydrolytically remove sialic acids from glycoconjugates. Neuraminidases are produced by both humans and their pathogens, and function in normal physiology and in pathological events. Identification of neuraminidase substrates is needed to reveal their mechanism of action, but high-throughput methods to determine glycan specificity of neuraminidases are limited. Here we use two glycan labeling reactions to monitor neuraminidase activity toward glycan substrates. While both periodate oxidation and aniline-catalyzed oxime ligation (PAL) and galactose oxidase and aniline-catalyzed oxime ligation (GAL) can be used to monitor neuraminidase activity toward glycans in microtiter plates, only GAL accurately measured neuraminidase activity toward glycans displayed on a commercial glass slide microarray. Using GAL, we confirm known linkage specificities of three pneumococcal neuraminidases and obtain new information about underlying glycan specificity.

Neuraminidases (sialidases) are enzymes that hydrolytically remove sialic acid from sialylated proteins and lipids. Neuraminidases are encoded by a range of human pathogens, including bacteria, viruses, fungi, and protozoa. Many pathogen neuraminidases are virulence factors, indicating that desialylation of host glycoconjugates can be a critical step in infection. Specifically, desialylation of host cell surface glycoproteins can enable these molecules to function as pathogen receptors or can alter signaling through the plasma membrane. Despite these critical effects, no unbiased approaches exist to identify glycoprotein substrates of neuraminidases. Here, we combine previously reported glycoproteomics methods with quantitative proteomics analysis to identify glycoproteins whose sialylation changes in response to neuraminidase treatment. The two glycoproteomics methods-periodate oxidation and aniline-catalyzed oxime ligation (PAL) and galactose oxidase and aniline-catalyzed oxime ligation (GAL)-rely on chemoselective labeling of sialylated and nonsialylated glycoproteins, respectively. We demonstrated the utility of the combined approaches by identifying substrates of two pneumococcal neuraminidases in a human cell line that models the blood-brain barrier. The methods deliver complementary lists of neuraminidase substrates, with GAL identifying a larger number of substrates than PAL (77 versus 17). Putative neuraminidase substrates were confirmed by other methods, establishing the validity of the approach. Among the identified substrates were host glycoproteins known to function in bacteria adherence and infection. Functional assays suggest that multiple desialylated cell surface glycoproteins may act together as pneumococcus receptors. Overall, this method will provide a powerful approach to identify glycoproteins that are desialylated by both purified neuraminidases and intact pathogens.

Carbohydrates, in addition to their metabolic functions, serve important roles as receptors, ligands, and structural molecules for diverse biological processes. Insight into carbohydrate biology and mechanisms has been aided by metabolic oligosaccharide engineering (MOE). In MOE, unnatural carbohydrate analogs with novel functional groups are incorporated into cellular glycoconjugates and used to probe biological systems. While MOE has expanded knowledge of carbohydrate biology, limited metabolism of unnatural carbohydrate analogs restricts its use. Here we assess metabolism of SiaDAz, a diazirine-modified analog of sialic acid, and its cell-permeable precursor, Ac4ManNDAz. We show that the efficiency of Ac4ManNDAz and SiaDAz metabolism depends on cell type. Our results indicate that different cell lines can have different metabolic roadblocks in the synthesis of cell surface SiaDAz. These findings point to roles for promiscuous intracellular esterases, kinases, and phosphatases during unnatural sugar metabolism and provide guidance for ways to improve MOE.

Cholera toxin (CT) enters and intoxicates host cells after binding cell surface receptors using its B subunit (CTB). The ganglioside (glycolipid) GM1 is thought to be the sole CT receptor; however, the mechanism by which CTB binding to GM1 mediates internalization of CT remains enigmatic. Here we report that CTB binds cell surface glycoproteins. Relative contributions of gangliosides and glycoproteins to CTB binding depend on cell type, and CTB binds primarily to glycoproteins in colonic epithelial cell lines. Using a metabolically incorporated photocrosslinking sugar, we identified one CTB-binding glycoprotein and demonstrated that the glycan portion of the molecule, not the protein, provides the CTB interaction motif. We further show that fucosylated structures promote CTB entry into a colonic epithelial cell line and subsequent host cell intoxication. CTB-binding fucosylated glycoproteins are present in normal human intestinal epithelia and could play a role in cholera.

SESSION II: Glycan Regulation of Immunity and Infection I Modulation of the innate immune responses to pathogenic Escherichia coli by paired Siglec receptors in humans and in mice Poster #: LB1 || Abstract #: 229 Flavio Schwarz1,2,3, Corinna S. Landig1,2,3, Shoib Siddiqui1,2,3, Ismael Secundino1,4,7, Andrea GarciaBingman1, Joshua Olson4, Nissi Varki1,5, Victor Nizet1,4,6, Ajit Varki1,2,3 1Glycobiology Research and Training Center, 2Department of Cellular and Molecular Medicine, 3Department of Medicine, 4Department of Pediatrics, 5Department of Pathology, 6Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093; 7Instituto de Biotecnología, Universidad Nacional Autónoma de México Overlapping Substrate Specificity of Nucleotide Sugar Transporters in the Fungal Pathogen, Aspergillus Fumigatus Poster #: LB2 || Abstract #: 230 Juliana Yeung1, Mark Warwas1, Brandon Kwok1, Helen Croft1, Lindsay Woof1, Amrit Bath1, Tysha Donnelly1, Linda Pinto1, Joe Tiralongo2, Thomas Haselhorst2, Margo M. Moore1 1Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada ; 2Institute for Glycomics, Griffith University, Queensland, Australia