Monocytes are a population of mononuclear lekocytes. The aim of this thesis was to select a suitable methodology for the isolation of monocytes and their cultivation into dendritic cells. For the experiment, bovine blood was taken from vena jugularis externa. This blood was used to isolate monocytes based on the density gradient of OptiPrep solution and Histopaque solution. The results showed that the method of isolation based on the density gradient of the Histopaque solution and the magnetic separation appeared to be a more efficient method. The monocyte population was cultured for 72 hours. Cells were analyzed by light microscopy and CD14 positive cells appeared to be transformed into dendritic cells. The purity of these cell population was determined by flow cytometry. Dendritic cells have a wide range of utility mainly in immunotherapy of various diseases and also play an important role in cancer therapy.

The macrophage receptors that mediate phagocytosis of Borrelia burgdorferi, the Lyme disease spirochete, are unknown despite this cell type's importance in promoting pathogen clearance and inflammation-mediated tissue damage. We now demonstrate that the β2 integrin, Complement Receptor 3 (CR3), mediates the phagocytosis of opsonized and non-opsonized spirochetes by murine macrophages and human monocytes. Although, expression of the surface proteins, CspA and OspE, protects B. burgdorferi from complement-mediated phagocytosis, the versatility of CR3 counteracts the ability of B. burgdorferi to interfere with complement activation and complement-derived opsonins, thus minimizing the bacteria's anti-complement strategy. Interaction of the spirochete with the integrin is not sufficient to internalize B. burgdorferi; however, phagocytosis occurs when the GPI-anchored protein, CD14, is coexpressed in CHO-CR3 cells. CR3-mediated phagocytosis occurs independently of MyD88-induced or inside-out signals but requires the translocation of the integrin to cholesterol rich membrane microdomains. Interestingly, the absence of CR3 leads to marked increases in production of TNF in vitro and in vivo, in spite of reduced spirochetal uptake. Overall, our data establish CR3 as a MyD88-independent phagocytic receptor for B. burgdorferi that also participates in the modulation of the proinflammatory output of macrophages. Macrophages are critical cellular components of the immune response to infectious agents. During infection with B. burgdorferi, macrophages infiltrate the cardiac tissue and induce the activation of invariant NKT cells, leading to the production of the protective cytokine IFNγ. The interaction of macrophages with infectious agents leads to the activation of several signaling cascades, including mitogen activated protein kinases, such as p38 MAP kinase. We now demonstrate that p38 MAP kinase-mediated responses are critical components to the immune response during infection with B. burgdorferi. The inhibition of p38 MAP kinase does not alter the ability of macrophages to phagocytose B. burgdorferi; however, inhibition of p38 during infection with B. burgdorferi results in increased carditis. Through the generation of transgenic mice that express a dominant negative form of p38 MAP kinase specifically in macrophages, we demonstrate that this kinase regulates the production of the iNKT attracting chemokine, MCP-1 and the infiltration of these cells to the cardiac tissue during infection. Overall, the inhibition of p38 MAP kinase during infection with B. burgdorferi specifically in macrophages results in the deficient infiltration of iNKT cells and their diminished production of IFNγ, leading to increased bacterial burdens and inflammation. These results show that p38 MAP kinase provides critical checkpoints for the protective immune response to the spirochete during infection of the heart.

Salmonella enterica serovar Typhimurium is an important cause of gastroenteritis in the United States and the developing world. Biofilm growth is an significant mechanism, which S. Typhimurium utilizes to contaminate food products and survive in the environment. Biofilms are also an important part of the infectious process for many pathogenic bacteria. As part of the biofilm, S. Typhimurium produces an extracellular matrix consisting of cellulose, extracellular DNA, and most importantly, the amyloid protein curli. Similar to amyloids associated with human diseases, curli is recognized by the innate immune system through Toll-Like Receptors (TLRs). Here, we studied the immune receptors recognizing curli as well as interactions between eDNA and curli during biofilm development in order to glean a better understanding of these complex bacterial communities and the immune response to them. Recently, our lab demonstrated that curli fibers are recognized by the TLR2/TLR1 complex. CD14 has been shown to be a common adaptor protein for TLR2/TLR1 complex in response to one of its ligands, tri-acylated lipopeptide, Pam3CSK4. In order to study the role of CD14 in the immune receptor complex recognizing curli, we utilized HeLa 57A cells, a human cervical cancer cell line that has a stably transfected luciferase reporter for Nf-κB activation. When these cells were transiently transfected with TLR2 and TLR1 together or with the addition of membrane-bound CD14, NfκB activation was enhanced by the presence of CD14 in response to purified curli, GST-tagged curli subunit (GST-CsgA), and the control lipopeptide Pam3CSK4. Soluble CD14 also increased NfκB activation in response to purified curli. Bone marrow derived macrophages (BMDM) from wild type (C57BL/6) mice produced more IL-6 and nitric oxide in response to stimulation with purified curli, GST-CsgA, and Pam3CSK4, than BMDMs deficient in CD14. Binding assays demonstrated direct binding of curli to all members of this hypothesized trimolecular complex, TLR2, TLR1, and CD14. Utilizing synthetic peptides corresponding to the fourth and fifth repeat of the CsgA monomer, CsgA R4-5, and its modified version, CsgA R4-5N122A deficient in forming amyloid fibers, we also showed that binding to CD14, and CD14 enhancement of IL-6 production required the fibrillar amyloid structure of curli. To study interactions between curli and eDNA in biofilms and the resulting immune response generated to composites formed by these ECM components, we analyzed biofilms of GFP expressing S. Typhimurium using confocal laser scanning microscopy (CLSM). Staining for amyloids with Congo Red revealed the presence of curli in the biofilms and staining with propidium iodide demonstrated the presence of extracellular DNA in the biofilms. Co-staining with TOTO-1, a nucleic acid stain, and Congo Red showed co-localization of the fluorescent signal for these molecules within the biofilms. DNase I treatment of the biofilms produced no significant change in biofilm thickness by confocal microscopy signifying that the biofilm, possibly eDNA, was resistant to DNase treatment. This was further confirmed by the presence of DNA in purified curli fibers, which were treated twice with DNase and RNase. Polymerization assays showed acceleration of amyloid polymerization in the presence of DNA from both bacteria and salmon sperm. CLSM of bone marrow derived dendritic cells demonstrated that DCs are able to sample antigens from biofilms. BMDCs also produced robust quantities of proinflammatory cytokines in response to wild type, msbB, and ΔfliCfljB S. Typhimurium biofilms and purified amyloid/DNA composites as measured by ELISA. Using BMDCs deficient in TLR2 and TLR9, we found that this cytokine production was partially dependent on TLR2, but did not require TLR9. Together, these findings significantly broaden our understanding of S. Typhimurium biofilms and the immune response to ECM components present in its biofilms. We now understand that a trimolecular complex of TLR2/TLR1/CD14 is required for full response to curli by innate immune cells. We also discerned that interactions between biofilm components aid biofilm development and create composites that are highly immunogenic. This new information enhances the need to explore the interaction between composite ligands and the immune system rather than only studying ligands individually. / Microbiology and Immunology

In einer Vielzahl von Arbeiten konnten anti-inflammatorische Eigenschaften von Ethylpyruvat (EP) aufgezeigt werden. An verschiedenen Modellen der Sepsis, des hämorrhagischen Schocks, von Verbrennungsschäden, des Apoplex oder der Ischämie und Reperfusion wurde bei der Behandlung mit EP ein protektiver Effekt sowie eine verminderte Produktion von pro-inflammatorischen Zytokinen nachgewiesen. Als biochemische Grundlage wurde die Interaktion von EP mit dem Transkriptionsfaktor NF-κB identifiziert, die spezifischen Regulationsmechanismen konnten bisher allerdings nicht zufriedenstellend aufgeklärt werden. In dieser Arbeit wurde als eine neue mögliche Erklärung für die anti-inflammatorischen Eigenschaften des EP und weiterer α-oxo-Karbonsäureester die Inhibierung der Glyoxalase I (Glo-I) aufgezeigt. In vitro-Experimente zur Enzymaktivität belegten die Hemmung der Glo-I durch EP, während α-Hydroxy-Karbonsäureester wie L-Ethyllaktat (EL) keine inhibierenden Eigenschaften aufwiesen. Dennoch waren sowohl EP als auch EL und weitere Laktatester in der Lage, die LPS-induzierte Produktion von pro-inflammatorischen Zytokinen wie IL-1β, IL-6, IL-8 und TNF-α von humanen immunkompetenten Zellen zu supprimieren und die Expression von Immunrezeptoren wie HLA-DR, CD14 und CD91 zu modulieren. Somit konnten erstmals anti-inflammatorische Eigenschaften von Laktatestern nachgewiesen sowie eine Verbindung zwischen den Glyoxalase-Enzymen und dem Immunsystem etabliert werden. Diese und weitere Ergebnisse zur Einflussnahme der Karbonsäureester auf die Zellvitalität präsentieren das Glyoxalasesystem als mögliches Ziel neuer Therapiekonzepte für die Immunsuppression und bestätigen dessen Bedeutung für die Entwicklung von Anti-Tumor-Agenzien.

Dendritische Zellen (DZ) sind essentiell für die Aktivierung von Immunantworten. Drei Flt3-abhängige DZ Populationen aus dem Blut bestehend aus konventionellen (kDZ) BDCA1+ DZs und BDCA3+ DZs und plasmazytoide DZs wurden bereits beschrieben. Hier wurden zum ersten Mal sich aus Monozyten entwickelnde DZ (moDZ), genauer BDCA1+CD14+ pro-inflammatorische DZ (pro-iDZ) aus periphärem Blut unter homöostatischen Bedingungen identifiziert. Isolierte pro-iDZ sekretierten spontan große Mengen an pro-inflammatorischen Zytokinen, die kDZ reifen ließen und T Zell Proliferation unterstützten. Sie waren BDCA1+CD14- DZ und CD14+CD16- Monozyten in der TH17 Zell Induktion überlegen. Pro-iDZ ähnliche BDCA1+CD14+ Zellen konnten durch imaging cycler microscopy in Geweben von Patienten die an Psoriasis, Dermatomyositis oder entzündetem Halonävus erkrankt waren identifiziert werden. Ihr Fehlen in gesunder Haut deutete eine Rekrutierung von pro-iDZs in entzündetes Gewebe an. Eine Verwandtschaftsanalyse von pro-iDZ zwischen Monozyten, kDZ des Blutes und in vitro generierten moDZ auf genomweiter Ebene wies auf einen monozytären Ursprung hin. Anylse mittels funktioneller Annotation auf differentiell exprimierten Genen zwischen pro-iDZ und Monozyten zeigte eine DZ spezifische Gensignatur auf. Diese Gene waren insgesamt in der gleichen Weise wie in kDZ und moDZ reguliert, das eine Entwicklung von Monozyten nach DZ nahelegte. Dieses Entwicklungskonzept wurde insofern unterstützt, indem unter entzündlichen Bedingungen kultivierte CD14+CD16- Monozyten BDCA1 Expression und DZ Funktion erlangten. Da pro-iDZ sehr ähnlich zu BDCA1+CD14+ Zellen aus entzündeter Haut waren und beide große Konvergenz mit zuvor beschriebenen BDCA1+CD14+ inflammatorischen DZ (infDZ) aus entzündeten Geweben aufwiesen, können pro-iDZ als direkte infDZ Vorläufer angesehen werden. Dadurch und wegen ihrer monozytären Herkunft können pro-iDZ als Beweis für die humane Differenzierung von Monozyten nach DZ in vivo betrachtet werden. / Dendritic cells (DCs) are critical for the activation of immune responses. Three Flt3-dependent blood DC populations including conventional BDCA1+ DCs and BDCA3+ DCs (cDCs) and plasmacytoid DCs were described previously. This work identifies for the first time human peripheral blood monocyte derived BDCA1+CD14+ pro-inflammatory DCs (pro-iDCs) during steady state. Isolated pro-iDCs spontaneously secreted high amounts of pro-inflammatory cytokines, which matured cDCs and promoted T cell proliferation. They were superior in priming TH17 cells when compared to BDCA1+CD14- DCs and CD14+CD16- monocytes. BDCA1+CD14+ cells resembling blood pro-iDCs as identified by imaging cycler microscopy were found in samples from patients suffering from psoriasis, dermatomyositosis and inflamed halo nevus. Their absence in healthy donor’s skin indicated a recruitment of pro-iDCs to sites of inflammation. Analysis of the developmental relationship of pro-iDCs between monocytes, blood cDCs and in vitro generated monocyte derived DCs (moDCs) on whole genome level strongly suggested a monocytic origin. Functional annotation analysis of differentially regulated genes between monocytes and pro-iDCs revealed a DC specific gene signature. In addition, these genes were overall regulated in the same way in blood cDCs and moDCs, indicating an ongoing development of pro-iDCs from monocytes towards DCs. This developmental concept was supported as CD14+CD16- monocytes cultured under inflammatory conditions gained BDCA1 expression and DC function. Since pro-iDCs were highly similar to BDCA1+CD14+ cells found in inflamed skin and as both showed a marked convergence with BDCA1+CD14+ inflammatory DCs (infDCs) present in inflamed tissues described previously, pro-iDCs can be regarded as immediate precursors of infDCs. Thus, in respect of a monocytic origin and a presumably inflammatory DC fate, pro-iDCs may constitute a missing link to prove human moDC differentiation in vivo.

Les rétrovirus endogènes humains ont longtemps été considérés comme d'inactifs fossiles de l'ADN humain, mais leur abondance (8%) a récemment été révélée grâce au séquençage du génome humain. Plusieurs études indépendantes ont montré une association au niveau moléculaire entre le rétrovirus endogène humain MSRV de la famille HERV-W et la sclérose en plaques (SEP) ainsi que la schizophrénie (SCZ). Les éléments de la famille HERV-W codent pour une protéine d'enveloppe (Env) très immunopathogène. Cette protéine active une cascade autoimmune et inflammatoire via l'interaction du récepteur TLR4 avec les cellules présentatrices d'antigène, provoque une dérégulation du système immunitaire et induit une cytotoxicité particulière. Grâce à un test ELISA développé pour la détection des protéines HERV-W ex vivo, la présence significative d'une antigénémie MSRV-Env a pu être détectée chez environ 75% des patients SEP, alors que tous les contrôles sains étaient négatifs. Une antigénémie positive d'environ 50% chez des patients SCZ pour les protéines Env et Gag a également été rapportée, montrant une corrélation significative avec un sous-groupe de patients ayant un niveau élevé de protéine C-réactive. De plus, un modèle animal d'encéphalomyélite autoimmune expérimentale a pu être reproduit avec l'utilisation de la protéine Env. Ce modèle a montré des signes d'inflammation et de démyélinisation confirmées par des analyses IRM et histologiques, ainsi qu'une autoimmunité anti-myéline. Un anticorps monoclonal, sélectionné pour ses propriétés inhibitrices par rapport à l'activation du TLR4 par MSRV-Env, a été testé in vivo avec ce nouveau modèle animal et in vitro avec des cellules immunitaires. Une inhibition significative des symptômes cliniques en comparaison avec des contrôles non traités a été obtenue et l'innocuité du traitement a été vérifiée. L'interaction de la protéine Env du rétrovirus MSRV avec des facteurs environnementaux pourrait être à la source de la cascade inflammatoire en association avec la SEP ou la SCZ. Cette protéine représente une nouvelle cible thérapeutique dans le cadre du développement prometteur d'un anticorps thérapeutique monoclonal. L'ensemble des ces travaux a contribué à montrer qu'une partie des rétrovirus endogènes humains ont retenu leur activité, ce qui ouvre de nouvelles perspectives de recherche dans le domaine des maladies complexes humaines / Human endogenous retroviruses (HERVs) have long been considered as inactive fossils in human DNA, but recent sequencing of the human genome revealed that they are very abundant and constitute approximately (8%) of the human genomic sequences. Recent independent molecular studies have also shown an association between the MS-associated retrovirus MSRV of the human endogenous retroviruses type “W” (HERV-W) family and Multiple Sclerosis (MS), as well as Schizophrenia (SCZ). HERV-W elements encode a powerful immunopathogenic envelope protein (Env) that activates a proinflammatory and autoimmune cascade through interaction with Toll-Like receptor 4 (TLR4) on antigenpresenting cells, triggers dysregulation of the immune system and mediates a peculiar cellular toxicity. Using a specific ELISA immunoassay for ex-vivo measurement of HERV-W proteins, a highly significant prevalence of MSRV-Env antigenemia in MS sera (about 75%) was reported, whereas all healthy controls were negative. A positive Env and Gag antigenemia (about 50%) was also found in SCZ patients, and a significant correlation with an elevated level of C-reactive protein was shown in a subgroup of SCZ patients. Moreover, the MSRV-Env protein was shown to reproduce the hallmarks of an Experimental Autoimmune Encephalomyelitis, an animal model for MS, with major inflammatory demyelination confirmed by MRI and histology, as well as anti-myelin autoimmunity. An anti-Env monoclonal antibody, selected for its inhibiting effects on MSRV-Env interaction with TLR4 in human lymphoid cell cultures, was tested in vivo with this new MS model and also in vitro with human immune cells. Significant inhibition and prevention of clinical symptoms compared to untreated controls were observed. These rodent models are also useful for initial investigation of the safety of antibody, since the Env protein is not expressed in animal species except for non-human primates. A relationship between environmental factors and the pro-inflammatory MSRV-Env protein is thus a possible hypothesis regarding initiation of a pathogenic cascade leading to diseases such as MS and SCZ. The MSRV-Env protein now represents a novel target, and the neutralizing antibody being developed by GeNeuro, a promising therapeutical approach for the cure of these severe neurological diseases

Leukocytes are activated in women with preeclampsia, but the class of leukocyte most likely to cause vascular dysfunction is not known. We hypothesized that neutrophils may be the class of leukocyte most involved in causing this dysfunction because neutrophils are the most abundant of the leukocytes and their numbers increase during pregnancy. In this study we compared vascular infiltration of neutrophils (CD66b) with monocytes/macrophages (CD14) and lymphocytes (CD99) in normal non-pregnant women (NNP), normal pregnant women (NP), and preeclamptic women (PE). There was no significant difference in the infiltration of lymphocytes into the maternal vasculature in PE as compared to NNP or NP. There was significantly more neutrophil infiltration into the systemic vasculature in PE women than in NP and NNP women. Monocytes/macrophages were present in tissue but not in vessels. We speculate that neutrophils are the class of leukocyte that causes the majority of vascular cell dysfunction in preeclampsia.

Insulin-produzierende Zellen als Ersatz für die beim Diabetes mellitus Typ 1 zerstörten Betazellen stellen einen hochattraktiven Forschungsansatz dar. Ziel dieser Arbeit war, Insulin-positive Zellen aus in vitro modifizierten Blutmonozyten zu gewinnen. Blutmonozyten sind nicht nur, wie bereits seit längerem bekannt, in der Lage, sich in Makrophagen und dendritischen Zellen zu differenzieren, sondern auch in eine Vielzahl nicht-phagozytierender Zellen, wie z.B. Insulin-produzierender Zellen. Für die optimale Zelltherapie ist zu fordern, dass die gewünschten Zellen in vivo nicht nur ihre Funktion beibehalten, sondern dass von diesen Zellen auch kein immunologisches Risiko für den Patienten ausgeht. Eine dauerhafte Immunsuppression, wie sie für die Vollorgantransplantation notwendig ist, ist für Zelltransplantate nicht angebracht. Hier besteht Übereinkunft, dass Immunsuppressiva, wenn überhaupt, nur kurzfristig einzusetzen sind. Blutmonozyten lassen sich einfach gewinnen und stünden somit als autologer Zellersatz für eine mögliche Zelltherapie zur Verfügung. Ein wesentlicher Aspekt dieser Arbeit war, die in vitro Differenzierung von Blutmonozyten zu charakterisieren. Dabei sollte die Expression von Insulin, Gluka¬gon und dem Glukosetransporter Glut-2 nachgewiesen werden. Auch morpho¬logische Veränderungen während der Kultur sollten beobachtet werden. Die kultivierten Monozyten entwickelten sich mit zunehmender Kulturdauer eindeutig zu Makrophagen. Dabei waren zwei verschiedene Zellmorphologien zu unterscheiden: Der erste Zelltyp (Typ 1) war oval mit Ausläufern. Der zweite Zelltyp (Typ 2) war sehr groß, teilweise mit einem Durchmesser von über 500 μm, häufig von ovaler Form und polynukleär. Dieser Zelltyp wies zudem häufig einen breiten, um das Kerngebiet gruppierten Saum auf. Mit zunehmender Kulturdauer dominierte dieser Zelltyp die Kultur. Der Großteil der Typ 1-Zellen blieb CD14 positiv. Gab es CD14-negative Zellen in der Kultur, so gehörten sie mit großer Wahrscheinlichkeit zu den Typ 2-Zellen. Nur in den in vitro modifizierten, nicht aber in den frisch isolierten Monozyten waren Insulin, C-Peptid, Glukagon und GLUT-2 immunhistochemisch nachzu¬weisen. Mit zunehmender Kulturdauer dominierten stark adhärente Makrophagen die Kultur. Das aus ca. 5x106 Monozyten isolierte Insulin senkte den Blutzuckerspiegel diabetischer Mäuse innerhalb einer Stunde nach Injektion um 66,1±12,8 Prozent (n=5). Zum Vergleich: 170 pg Humaninsulin senkten den Blutzuckerspiegel um 84,2±8,4 Prozent (n=4). Insulin-negative Monozyten beeinflussten nicht den Blutzuckerspiegel diabeticher Mäuse. Zudem lassen erste elektronenmikroskopische Aufnahmen von in vitro modifizierten Monozyten Insulin-haltige Vesikel erkennen. Zum jetzigen Zeitpunkt ist gesichert, dass in vitro modifizierte Monozyten über biologisch aktives Insulin verfügen, das den Blutzuckerspiegel diabetischer Tiere senkt. Der Nachweis von C-Peptid deutet zudem darauf hin, dass es sich hierbei um de novo Insulin handelt. Dies bedeutet, dass das Insulin-Gen in den in vitro modifizierten Monozyten aktiv ist und sie Insulin mRNA exprimieren, die anschließend in Insulin translatiert wird. Der elektronenmikroskopische Nachweis Insulin-haltiger Granula deutet außerdem darauf hin, dass diese Zellen Insulin speichern können. Inwieweit sie jedoch auch zur Glukose-ab¬hängigen Insulin-Ausschüttung in der Lage sind, ist in weiteren Experimenten zu überprüfen. / Promising cell replacement strategies may restore insulin-secretion in patients with type 1 diabetes. Cells suitable for such a strategy must demonstrate prolonged function in vivo and should not induce immunological responses. A chronic immuno¬suppressive therapy which is requisite for organ grafts is not suitable for cell grafts. Peripheral human blood monocytes easily obtained from patients can be modified in vitro into insulin-positive cells and, therefore may be perfect for autologic cell replacement strategies. The purpose of this study was to characterise cultured monocytes for the presence of insulin and C-peptide as a well-defined indicator for insulin synthesis by immunohistochemistry. In addition, the expression of glucagon and the glucose transporter Glut-2 was proved. During culture, monocytes differentiated into cells with unique morphology. The cell type 1 showed a lengthy-oval shape with branches, like fibroblasts. The cell type 2 was very large, oval in shape and often polynuclear. These cells demonstrated the morphology of long-term cultured macrophages and dominated the culture in the course of time. Cultured monocytes were positive for insulin, C-peptide, glucagon and Glut-2 in contrast to freshly isolated monocytes. Evidence from the electron microscopy indicated that insulin-positive monocytes store their insulin in vesicles. Insulin isolated from 5x106 insulin-positive monocytes was able to reduce blood glucose levels of diabetic mice (> 22 mmol/L) about 66.1±12.8 percent (n=5) within one hour after injection. In comparison, 170 pg of human insulin decreased blood glucose levels of diabetic mice about 84.2±8.4 percent (n=4). Insulin-negative monocytes were unable to reduce blood glucose levels. In this study the possibility of modifying monocytes into insulin-positive cells during culture was confirmed. The detection of C-peptide supports the existence of de novo insulin within these cells which was stored in granula and biologically active. In further studies these cells have to prove whether they are really able to secrete insulin in a dose-dependent manner qualifying them as long-term cell replacements.

Background: Patients with burns are susceptible to organ failure, and there is indirect evidence that leukocytes may contribute to this process. They may change the expression of cell-surface receptors after certain stimuli, for example, the burn. We therefore aimed to assess the changes induced by the burn in the expression of leukocyte cell-surface receptors CD11b, CD14, CD16, and CD62L on the surface of PMNs and monocytes. We also wanted to examine the dynamics of this activation during the first week after the burn, and to relate it to the size of the injury. Methods: Ten patients with burns of andgt;15% (TBSA) were included in the study. Blood samples were collected on arrival and every consecutive morning during the first week. Healthy volunteers acted as controls. Results: PMN CD11b expression was increased. The extent of PMN CD11b expression correlated negatively to the size of the full thickness burn. Monocyte CD14 expression increased initially but there was no relation to the size of the burn. PMN CD16 expression decreased initially during the first days and the decrease was related to burn size. CD62L did not vary depending on the burn in either PMN or monocytes during the first week after the burn. Conclusion: This study showed that specific receptors on the surface of leukocytes (PMN CD11b, monocyte CD14 and PMN CD16) are affected by the burn. Expression of PMN CD11b and CD16 are related to burn size. Burn-induced effects on the expression of PMN receptors, such as PMN CD11b and CD16, may contribute to burn-induced infection susceptibility. / Original Publication: Joakim Johansson, Florence Sjögren, Mikael Bodelsson and Folke Sjöberg, Dynamics of leukocyte receptors after severe burns: An exploratory study, 2011, BURNS, (37), 2, 227-233. http://dx.doi.org/10.1016/j.burns.2010.08.015 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/

Human milk contains ~ 25 µg/mL of soluble cluster of differentiation 14 (sCD14) protein, a pattern recognition receptor (PRR) that triggers the innate immune system to respond to bacterial lipopolysaccharide (LPS). To date, the role of CD14 in the digestive tract of breast fed infants has not been well characterized and is the subject of this thesis. To investigate the biodistribution of proteins such as CD14 in vivo, a novel method for 14C radiolabeling of proteins to high specific radioactivity was developed using in vacuo methylation. Bovine serum albumin (BSA) and casein were used as test proteins to determine the following: 1) The efficacy of the in vacuo radiolabeling procedure; 2) The extent of incorporation of the 14C-label into the organs of oro-gastric gavaged 10 day old Sprague Dawley rats. [14C]BSA, [14C]casein and [14C]CD14 were prepared with specific radioactivities of 10 400, 10 800 and 163 000 dpm/µg, respectively. After feeding 6.25 µg of 14C-labeled proteins, quantifiable levels of 14C were found in the stomach, jejunum, duodenum, ileum, large intestine, intestinal luminal flushes, blood, liver, spleen and kidneys of rats. The accumulation of radiolabel in the organs of [14C]CD14 fed rats was temporally and spatially distinct from [14C]BSA and [14C]casein. Most notably, the label persisted in the stomach 480 min post-gavage. To design a neonate animal model for biodistribution, the segmental and total gastrointestinal transit times (GItt) were measured in two litters of 10 and 15 day old Sprague Dawley rat pups using barium sulfate. Ten day old rat pups that remained with and without the dam had a total gastrointestinal transit time of 13.8 ± 0.9 hr and 9.3 ± 0.7 hr, respectively. This decrease (p<0.05) in total gastrointestinal transit time in the absence of the dam was age dependent, as it was not observed (p>0.05) in the 15 day old rat pup litter. The immunological impact of an exogenous sCD14 source was examined in human peripheral blood mononuclear cells (PBMC). Pre-treatment of CD14+ monocytes with sCD14 had a protective effect, one of reducing the production of proinflammatory cytokines (TNF-α, IL-6, IL-8, IL-1β) when challenged with LPS. 14C was absorbed by neonate rats upon ingestion of [14C]CD14 and exposure to relatively high concentrations of rCD14 led to a reduction in inflammation. This may be beneficial to initial gut colonization in breast-fed newborns. / Alexander Graham Bell NSERC CGS M scholarship. Japan Society for the Promotion of Sciences, Summer in Japan Fellowship. Funded by the Canadian Institutes of Health Research, Institute of Nutrition Metabolism and Diabetes Grant #82816 “Fate and function of breast milk and recombinant human CD14 at mammary and newborn gastrointestinal mucosal epithelia”.