The mannose receptor (MR) is a C-type lectin expressed by dendritic cells (DCs). We have investigated the ability of MR to recognize glycosylated allergens. Using a gene silencing strategy, we have specifically inhibited the expression of MR on human monocyte-derived DCs. We show that MR mediates internalization of diverse allergens from mite (Der p 1 and Der p 2), dog (Can f 1), cockroach (Bla g 2), and peanut (Ara h 1) through their carbohydrate moieties. All of these allergens bind to the C-type lectin-like carbohydrate recognition domains 4–7 of MR. We have also assessed the contribution of MR to T cell polarization after allergen exposure. We show that silencing MR expression on monocyte-derived DCs reverses the Th2 cell polarization bias, driven by Der p 1 allergen exposure, through upregulation of IDO activity. In conclusion, our work demonstrates a major role for MR in glycoallergen recognition and in the development of Th2 responses.

Surface Ig (sIg) of follicular lymphoma (FL) is vital for tumor cell survival. We found previously that the Ig in FL is unusual, because the variable region genes carry sequence motifs for N-glycan addition. These are introduced by somatic mutation and are tumor specific. Unexpectedly, added glycans terminate at high mannose, suggesting a potentially important interaction of FL cells with mannose-binding lectins of the innate immune system. We have now identified mannosylated IgM at the surface of primary lymphoma cells. Recombinant lectin domains of the mannose receptor (MR) or DC-SIGN bind mannosylated Igs in vitro and bind to FL cells, signaling sIgM-associated increases in intracellular Ca 2+ . Lectins also bind to normal B cells but fail to signal. In contrast, anti-Ig signaled similarly in both FL and normal B cells. Mannosylation patterns were mimicked by FL Ig-derived single-chain Fvs (scFv), providing probes for potential receptors. Mannosylated scFv bound specifically to the lectin domains of the MR and DC-SIGN and blocked signaling. Mannosylated scFv also bound to DC-SIGN on the surface of dendritic cells. This unique lymphoma-specific interaction of sIg with lectins of innate immunity reveals a potential route for microenvironmental support of tumor cells, mediated via the key B-cell receptor.B cell | B-cell receptor | B-cell lymphoma | immunoglobulin

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Allergens are initiators of both innate and adaptive immune responses. They are recognised at the site of entry by epithelial and dendritic cells (DCs), both of which activate innate inflammatory circuits that can collectively induce Th2 immune responses. In an attempt to have a better understanding of the role of carbohydrates in the recognition and uptake of allergens by the innate immune system, we defined common glycosylation patterns in major allergens. This was done using labelled lectins and showed that allergens like Der p 1 (Dermatophagoides pteronyssinus group 1), Fel d 1 (Felis domisticus), Ara h 1 (Arachis hypogaea), Der p 2 (Dermatophagoides pteronyssinus group 2), Bla g 2 (Blattella germanica) and Can f 1 (Canis familiaris) are glycosylated and that the main dominant sugars on these allergens are 1–2, 1–3 and 1–6 mannose. These observations are in line with recent reports implicating the mannose receptor (MR) in allergen recognition and uptake by DCs and suggesting a major link between glycosylation and allergen recognition. We then looked at TSLP (Thymic Stromal Lymphopoietin) cytokine secretion by lung epithelia upon encountering natural Der p 1 allergen. TSLP is suggested to drive DC maturation in support of allergic hypersensitivity reactions. Our data showed an increase in TSLP secretion by lung epithelia upon stimulation with natural Der p 1 which was carbohydrate dependent. The deglycosylated preparation of Der p 1 exhibited minimal uptake by DCs compared to the natural and hyperglycosylated recombinant counterparts, with the latter being taken up more readily than the other preparations. Collectively, our data indicate that carbohydrate moieties on allergens play a vital role in their recognition by innate immune cells, implicating them in downstream deleterious Th2 cell activation and IgE production.

Background: Allergen uptake by DCs is central to allergic sensitization.Results: DC-SIGN recognizes major allergens from house dust mite and dog. However, silencing DC-SIGN leads to Th2 differentiation.Conclusion: DC-SIGN is a newly identified receptor for Der p 1 and Can f 1 that appears to support Th1 cell differentiation.Significance: Understanding of how allergic responses are selected and propagated is essential for developing novel therapies.

Objective: The aim of this study was to determine the distribution and antibiotic susceptibility patterns of bacterial strains isolated from patients with community-acquired urinary tract infections (UTIs) at the Infectious Diseases Hospital, Kuwait. Materials and Methods: The study was conducted over a 7-year period. Patient information was obtained from medical record files. Antibiotic-sensitivity testing was performed by disk diffusion. E test and double disk diffusion methods were used to study the production of extended spectrum β-lactamases. Results: Of the 14,042 urine samples processed, significant bacteriuria (>10⁵ cfu/ml) was detected in 1,606 (11.4%). The majority (74.5%) of the isolates were from women while the remaining 25.5% were from men. The majority of infections (75%) were due to Enterobacteriaceae, coagulase-negative staphylococci (10.3%) and group B streptococci (8.7%). Among the gram-negative enteric bacilli high prevalence of resistance to ampicillin, amoxicillin/clavulanic acid, cephalothin, and trimethoprim/sulfamethoxazole was observed. Increasing resistance to ciprofloxacin and gentamicin was observed in E. coli isolates over the 7 years. Multiple resistance was detected in 53.8 and 41% of E. coli and Klebsiella spp. strains, respectively. No glycopeptide-resistant enterococci were isolated. Conclusion: This study revealed that Enterobacteriaceae were the predominant bacterial pathogen of community-acquired UTIs in Infectious Diseases Hospital, Kuwait. It also demonstrated an increasing resistance to ciprofloxacin, gentamicin and the production of extended spectrum β-lactamase among UTI pathogens in the community.

BackgroundSampling the microenvironment at sites of microbial exposure by dendritic cells (DC) and their subsequent interaction with T cells in the paracortical area of lymph nodes are key events for initiating immune responses. Most of our knowledge of such events in human is based on in vitro studies performed in the absence of extracellular matrix (ECM) proteins. ECM in basement membranes and interstitial spaces of different tissues, including lymphoid organs, plays an important role in controlling specific cellular functions such as migration, intracellular signalling and differentiation. The aim of this study was, therefore, to investigate the impact of two abundant ECM components, fibronectin and laminin, on the phenotypical and functional properties of DC and how that might influence DC induced T-cell differentiation.Methodology/Principal FindingsHuman monocyte derived DC were treated with laminin and fibronectin for up to 48 hours and their morphology and phenotype was analyzed using scanning electron microscopy, flow cytometry and real time PCR. The endocytic ability of DC was determined using flow cytometry. Furthermore, co-culture of DC and T cells were established and T cell proliferation and cytokine profile was measured using H3-thymidine incorporation and ELISA respectively. Finally, we assessed formation of DC-T cell conjugates using different cell trackers and flow cytometry. Our data show that in the presence of ECM, DC maintain a ‘more immature’ phenotype and express higher levels of key endocytic receptors, and as a result become significantly better endocytic cells, but still fully able to mature in response to stimulation as evidenced by their superior ability to induce antigen-specific T cell differentiation.ConclusionThese studies underline the importance of including ECM components in in vitro studies investigating DC biology and DC-T cell interaction. Within the context of antigen specific DC induced T cell proliferation, inclusion of ECM proteins could lead to development of more sensitive assays.

A combination of patient amenorrhea, BMI, total testosterone, anti-Müllerian hormone, ovarian volume, ovarian stromal artery pulsatility index, and visceral fat area could be used to predict clomiphene-citrate treatment response in patients with PCOS experiencing infertility. ClinicalTrials.gov: NCT02269306.