Joanna Lukawska

Real-time differential tracking of human neutrophil and eosinophil migration in vivo

BACKGROUND Hitherto, in vivo studies of human granulocyte migration have been based on indiscriminate labeling of total granulocyte populations. We hypothesized that the kinetics of isolated human neutrophil and eosinophil migration through major organs in vivo are fundamentally different, with the corollary that studying unseparated populations distorts measurement of both. METHODS Blood neutrophils and eosinophils were isolated on 2 separate occasions from human volunteers by using Current Good Manufacturing Practice CD16 CliniMACS isolation, labeled with technetium 99m-hexamethylpropyleneamine oxime, and then reinfused intravenously. The kinetics of cellular efflux were imaged over 4 hours. RESULTS Neutrophils and eosinophils were isolated to a mean purity of greater than 97% and greater than 95%, respectively. Activation of neutrophils measured as an increase in their CD11b mean fluorescence intensity in whole blood and after isolation and radiolabeling was 25.98 ± 7.59 and 51.82 ± 17.44, respectively, and was not significant (P = .052), but the mean fluorescence intensity of CD69 increased significantly on eosinophils. Analysis of the scintigraphic profile of lung efflux revealed exponential clearance of eosinophils, with a mean half-life of 4.16 ± 0.11 minutes. Neutrophil efflux was at a significantly slower half-life of 13.72 ± 4.14 minutes (P = .009). The migration of neutrophils and eosinophils was significantly different in the spleen at all time points (P = .014), in the liver at 15 minutes (P = .001), and in the bone marrow at 4 hours (P = .003). CONCLUSIONS The kinetics of migration of neutrophils and eosinophils through the lung, spleen, and bone marrow of human volunteers are significantly different. Study of mixed populations might be misleading.

Allergy to vitamin B12: two cases of successful desensitization with cyanocobalamin

Panrico and Bimbo (Bimbo S.A.U., Barcelona, Spain) bread extracts revealed IgE-binding bands at 12–17 kDa, in all extracts, 28 kDa in broad been extract, 50 kDa in all extracts except Hacendado bread extract and >50 kDa in all extracts (Fig. 1). Preincubation of serum from the patient with the broad been extract resulted in complete inhibition of IgE-binding to presliced extract proteins. These results demonstrate the existence of common allergenic structures between broad bean and commercial presliced breads, probably caused by the presence of broad bean flour (including Hacendado bread, with no broad bean flour declared on the label). Peanut and soy are considered the legumes most frequently involved in human food allergy in Anglo-Saxon countries and Japan. However, in Spain with a typical Mediterranean diet, lentils are implied in 78% of children allergic to legumes, chick-peas in 72%, peas in 36% and peanuts in 36% (3, 4). There is another legume, broad bean from which allergy has not been reported. It is a dicotyledonous plant belonging to Fabales order and Papilionaceae family that adapts to any kind of soil, favoured by coastal climates and moderated temperatures. They are consumed ripe or cooked and lately we can found it as flour in some kind of breads and soups. Bernhisel-Broadbent discovered that most of their 41 legume-allergic patients were allergic to only one legume (5). However, in Spain the majority of the patients have symptoms with more than one legume (median three legumes) (6) and, in contrast, white bean, green bean and soy are well tolerated by children allergic to legumes. In conclusion, we have demonstrated the existence of allergens from broad beans in a slice of bread that caused a type-I reaction in a legume-allergic patient. It should be recommended an extensive labelling of commercial foods to avoid unexpected reactions in susceptible allergic patients.

Imaging Inflammation in Asthma: Real Time, Differential Tracking of Human Neutrophil and Eosinophil Migration in Allergen Challenged, Atopic Asthmatics in Vivo

Background It is important to study differential inflammatory cellular migration, particularly of eosinophils and neutrophils, in asthma and how this is influenced by environmental stimuli such as allergen exposure and the effects of anti asthma therapy. Methods We isolated blood neutrophils and eosinophils from 12 atopic asthmatic human volunteers (Group 1 — four Early Allergic Responders unchallenged (EAR); Group 2 — four Early and Late Allergic Responders (LAR) challenged; Group 3 — four EAR and LAR challenged and treated with systemic corticosteroids) using cGMP CD16 CliniMACS. Cells were isolated prior to allergen challenge where applicable, labelled with 99mTc-HMPAO and then re-infused intravenously. The kinetics of cellular influx/efflux into the lungs and other organs were imaged via scintigraphy over 4 h, starting at 5 to 6 h following allergen challenge where applicable. Results Neutrophils and eosinophils were isolated to a mean (SD) purity of 98.36% (1.09) and 96.31% (3.0), respectively. Asthmatic neutrophils were activated at baseline, mean (SD) CD11bHigh cells 46 (10.50) %. Isolation and radiolabelling significantly increased their activation to > 98%. Eosinophils were not activated at baseline, CD69+ cells 1.9 (0.6) %, increasing to 38 (3.46) % following isolation and labelling. Analysis of the kinetics of net eosinophil and neutrophil lung influx/efflux conformed to a net exponential clearance with respective mean half times of clearance 6.98 (2.18) and 14.01 (2.63) minutes for Group 1, 6.03 (0.72) and 16.04 (2.0) minutes for Group 2 and 5.63 (1.20) and 14.56 (3.36) minutes for Group 3. These did not significantly differ between the three asthma groups (p > 0.05). Conclusions Isolation and radiolabelling significantly increased activation of eosinophils (CD69) and completely activated neutrophils (CD11bHigh) in all asthma groups. Net lung neutrophil efflux was significantly slower than that of eosinophils in all asthma study groups. There was a trend for pre-treatment with systemic corticosteroids to reduce lung retention of eosinophils following allergen challenge.

Antibiotic Allergy, When to Test, Challenge or Desensitise

Antibiotics are widely used for treatment of bacterial infections and for prophylaxis during instrumental procedures and in certain conditions such as immunodeficiency and splenectomy. Hypersensitivity (allergic) reactions are unpredictable and can occur in some patients even if they have taken the antibiotic in the past with no reaction. Drug allergy accounts for 11.3% of all adverse drug reactions. Drug allergy drugs can be generally classified (according to the World Allergy Organization) based on timing of symptoms into immediate (Immunoglobulin E (IgE) mediated) occurring within 1 hour and delayed (non IgE mediated) allergic reactions occurring after 1 hour. Many patients are mislabeled with drug allergy especially when the diagnosis is made based on history alone. In such cases, a referral to an allergist is important to confirm or exclude allergy through a detailed clinical history, in vitro and/or in vivo testing, as over diagnosis of drug allergy leads to the unnecessary use of broader spectrum and expensive antibiotics contributing to the emergence of multidrug resistant pathogens. Also, in cases of confirmed drug allergy it is important to establish potential cross reactivity with other drugs. Equally, patients with confirmed drug allergy, who have an absolute requirement for the drug or cross reactive drug (as in penicillin allergic females with syphilis) can undergo a process of desensitization in order to complete their treatment through induction of temporary tolerance of the drug.

The effect of prednisolone on Tc99m-HMPAO pure eosinophil and neutrophil radiolabelling efficiency, and their kinetics in vivo, in real time

Aim: Inflammatory bowel disease (IBD) is defined as a chronic relapsing idiopathic inflammation of the gastrointestinal tract. The two main clinical forms of this disease family are Crohn’s Disease (CD) and Ulcerative Colitis (UC). IBD affects an estimated 3.6 million individuals in Europe and North America. To date it is thought that IBD is the result of continual activation of the mucosal immune system. In order to better understand this disease family an in-house developed animal model was implemented and characterized with [18F]FDG (used to illustrate the increased glucose consumption associated with inflammatory processes) and also with TSPO 18 kDa radioligand [18F]DPA-714, an established radiotracer for the study of inflammation within the central nervous system. Materials and Methods: Colonic inflammation was induced in male Wistar rats weighing between 200-250 g by rectal administration of trinitrobenzenesulfonic acid (TNBS) at 4cm from the anal orifice. Control animals were administered, 0.9% aq. sodium chloride analogously. A Siemens Inveon PET/CT tomograph, dedicated to small animals, was used to acquire [18F]FDG images on day 7 post TNBS administration and [18F]DPA714 images the following day. Rats were then sacrificed by an i.v. injection of pentobarbital, and then the lower intestine was extracted and analyzed by immunohistochemistry to determine macrophage infiltration and the presence of TSPO. Results: PET image analysis clearly shows an important accumulation of both radiotracers within the intestinal walls of treated animals in comparison to control animals. Mean levels of [18F]FDG uptake in treated and control animals were 1.20 ± 0.56 %ID/cc and 0.43 ± 0.18 %ID/cc, respectively. Comparable results were found when using [18F]DPA-714, with mean level of uptake in treated and control animals of 1.21 ± 0.62 %ID/cc and 0.46 ± 0.23 %ID/cc, respectively. Immunohistochemistry analysis revealed a higher presence of macrophages in TNBS treated animals. Expression of TSPO was largely increased in the treated animals, when compared to the controls animals, and mainly localized in macrophages cells. Conclusion: Preliminary results seem to indicate that [18F]DPA-714 is an adapted tracer for the study of inflammation of IBD in our animal model. Beyond this, data demonstrating that [18F]DPA-714 could be used to characterize and quantify the level of inflammation during the disease evolution, within the TNBS treated animals, will also be presented. OP366 Surface displayed SNAP-tag as a novel tool for study of Grampositive bacterial infections. B. Mills, V. Steele, J. C. A. Luckett, R. O. Awais, P. Duncanson, V. Griffiths, A. Cockayne, M. Xu, I. Correa, A. C. Perkins, P. Williams, P. Hill; School of Molecular Medical Sciences, University of Nottingham, Nottingham, UNITED KINGDOM, Radiological and Imaging Sciences, University of Nottingham, Nottingham, UNITED KINGDOM, School of Biological and Chemical Sciences, Queen Mary University of London, London, UNITED KINGDOM, New England Biolabs, Inc, Ipswich, ME, UNITED STATES, School of Biosciences, University of Nottingham, Nottingham, UNITED KINGDOM. Introduction: The design of specific probes for in vivo molecular imaging of microbial infections remains one of the greatest challenges to overcome before useful, functional data can be obtained. An increasingly attractive approach for probe design is to express a ligand-binding protein within a cell, which may then covalently bind specific synthetic ligands with attached imaging moieties. One such labelling system is the commercially available SNAP-tag. SNAP-tag specifically and covalently binds O2-benzylguanine (BG) compounds, which may have fluorophores or other functional elements attached at the 4’ position of their benzyl ring. We have designed a BG ligand labelled with Tc, suitable for SPECT imaging. We propose to utilise this technology for the imaging of Staphylococcal infection in vivo with the view to investigate bacterial pathogenicity and to visualise the effect potential antimicrobials may have on bacterial load. Methods: The SNAP-tag gene was codon optimised for expression in the Gram positive bacterium Staphylococcus aureus and fused with an N-terminal spa secretion leader sequence and a Cterminal spa cell-wall anchoring domain. The N-terminal fusion directs the expressed SNAP-tag towards the cell exterior where the C-terminal domain is recognised by the cell-wall sorting enzyme sortase A, covalently anchoring SNAPtag in such a way that the ligand binding domain decorates the cell surface. A novel 99m Tc-HYNIC–NH-BG ligand for SPECT imaging was prepared by coupling BG to HYNIC and radiolabelling with NaTcO4 in the presence of tricine as co-ligand. Radiochemical yields >99% were obtained. nanoSPECT-CT imaging will be used to assess the functional data produced by using SNAP-tag expressing S. aureus cells in in vivo infection models. Results: We have demonstrated that SNAP-tag was expressed and exported to the cell wall where it was covalently anchored. Deletion of the sortase A enzyme prevented attachment of the SNAP-tag to the cell wall, as determined by Western blot. Once situated within the cell wall, SNAP-tag was functional and able to specifically bind cell-impermeable fluorescent BG ligands and our synthesised precursor HYNIC-NH2-BG ligand, as determined by confocal microscopy and fluorometry assay. Pilot in vivo studies for fluorescence optical imaging and nanoSPECT-CT imaging with the novel 99m Tc-HYNIC-NH-BG ligand are currently under development to visualise S. aureus infections in mouse models. Conclusions: This approach should allow a higher sensitivity to be achieved when investigating bacterial infections in real time compared to current molecular imaging techniques, thus allowing bacterial virulence and the potential effects of new antimicrobials to be assessed. OP367 Dual imaging of lipopolysaccharides (LPS) by SPECT-CT and Confocal Microscopy. M. Moreau, V. Duheron, B. Collin, W. Sali, C. Bernhard, C. Goze, T. Gautier, J. Pais de Barros, V. Deckert, F. Brunotte, L. Lagrost, F. Denat; ICMUB UMR CNRS 6302, Dijon, FRANCE, INSERM UMR866, Dijon, FRANCE, Centre Georges-François Leclerc, Dijon, FRANCE, Centre Hospitalier Universitaire, Dijon, FRANCE. Introduction: Lipopolysaccharides (LPS) or endotoxins are found inserted in the outer membrane of Gram-negative bacterias. Their appearance in blood stream triggers a massive secretion of pro-inflammatory cytokines in mammals. A controlled response allows the neutralization and elimination of LPS, whereas an excessive inflammatory response leads to severe circulatory and respiratory defects. It is the endotoxemic shock or septic shock that can leads to death. Many approaches are used to study LPS, including labeling with radiochemicals (3H, 125I, 99mTc or 51Cr) or with fluorophores (FITC, Alexa488, Bodipy). Bimodality is attracting more and more interest in the field of molecular imaging since the combination of two different techniques may provide complementary information, thus improving the accuracy of diagnosis. Combining nuclear modalities (PET or SPECT) with optical imaging is of particular interest, and the similar sensitivities of the two techniques allows to fuse the signaling moieties into a unique molecule, called monomolecular multimodality imaging agent (MOMIA), ensuring a same biodistribution of the two probes. Method: A recently described bimodal probe, namely DOTA-Bodipy-NCS, has been covalently attached to LPS. The integrity of the LPS after labeling procedure was checked by SDS-PAGE electrophoresis and βhydroxymyristate titration (BHM). Pro-inflammatory activity of LPS was assessed by quantification of cytokines released by differentiated THP-1 cells. This bioconjugate was then radiometallated for SPECT-CT biodistribution imaging. Results: DOTABodipy-LPS was metallated with 111In to yield a high specific activity (600 MBq.mg1), with a radiochemical purity >98 % after purification. Biodistribution of the radiolabeled compound was then evaluated in vivo in WT mice by SPECT-CT imaging. Radiolabeled LPS is rapidly eliminated from the bloodstream and accumulates in spleen and liver. Liver slices were then analyzed by confocal microscopy, and specific fluorescent signals in the cytoplasm of hepatocytes were detected, confirming the accumulation of 111In-DOTA-Bodipy-LPS in the liver. Conclusion: These results demonstrate the efficiency of the conjugation process of our bimodal probe. It made it possible to perform both non-invasive SPECT and ex vivo fluorescence imaging of LPS biodistribution, underlining its liver uptake for further detoxification. The 111In-DOTA-Bodipy-LPS probe arises here as a relevant tool to identify key components of LPS detoxification in vivo paving the way to therapeutic issues in the field of sepsis. Acknowlegement: Support was provided by the CNRS, the University of Burgundy, the Conseil Régional de Bourgogne. O P _ M o nd ay S178 Eur J Nucl Med Mol Imaging (2013) 40 (Suppl 2):S89–S567Affibody molecules constitute a class of small (7 kDa) scaffold proteins that can be engineered to have excellent tumor targeting properties. High reabsorption in kidneys complicates development of ...