1.
Rodríguez-Piñeiro, Ana María, et al.
(författare)
The colonic mucus protection depends on the microbiota
2015
Ingår i: Gut microbes. - : Informa UK Limited. - 1949-0976 .- 1949-0984. ; 6:5, s. 326-30
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt) abstract
The intestinal mucus is a pivotal part of our intestinal protection. It provides slow diffusion of protective molecules, trapping of luminal material as bacteria and smooth transport in the small intestine. In colon it restricts bacterial access to the epithelium limiting the responses to the enormous bacterial load present at this location. The development of these systems depends on the microbiota composition as seen in our recent study comparing the mucus phenotype in 2 colonies kept in different husbandries within the same SPF animal facility. One colony had impenetrable colonic mucus while the other colony had more penetrable mucus. The mucus phenotypes were transmitted via the microbiota and clear differences in its composition could be detected. Candidates associated with the different colonies were identified but the observed mucus difference could not be assigned to a specific bacterium.
2.
Bratanis, Eleni
(författare)
Bacterial antibody hydrolyzing enzymes – as bacterial virulence factors and biotechnological tools
2019
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Antibodies are an essential part of the human immune system, and antibody mediated immunity has been an area of interest for many researchers for almost a century. An accumulation of knowledge regarding antibody structure, glycosylation and receptor interactions has contributed to the current understanding of antibody mediated immunity. It has more recently become evident how bacteria and other microorganisms evade host recognition and eradication through specific antibody degradation or modification. The importance of antibody glycosylation and how glycan modification can fine-tune the elicited immune response has also contributed to the development of antibody-based drugs with improved clinical efficacy. In turn these insights have paved the way and created a need for the development of biotechnological methods and tools to specifically engineer antibodies with defined properties, for analysis to ensure quality and safety, and for improved antibody purification.This thesis highlights the importance of glycosylation for antibody function and presents different aspects and applications of antibody modifications by bacteria. We show, for the first time, activity of the IgG-specific Streptococcal endoglycosidase EndoS during Streptococcus pyogenes infection, clearly demonstrating that EndoS contributes to S. pyogenes pathogenesis and bacterial survival in the context of adaptive immunity. Further this thesis presents the use of bacterial enzymes as antibody modifying tools and their potential as binding reagents for selective antibody purification. The identification and characterization of two novel proteases, BspK and BspE exhibiting unique IgG and IgA cleavage profiles respectively, from Bdellovibrio bacteriovorus highlights the potential of using Bdellovibrio as a source for the identification of novel enzymes with biotechnological applications. Finally, I present the development of a novel method for selective antibody purification, using the inactive variants of the bacterial enzymes EndoS and EndoS2, ensuring the purification of native, correctly folded and modified antibodies.
3.
4.
Munthe, Christian, 1962
(författare)
Etiska aspekter på regenerativ medicin : Ethical aspects on regenerative medicine
2003
Ingår i: SNIB-konferensen 2003, Chalmers tekniska högskola, Göteborg, 16-18 maj 2003.
Konferensbidrag (övrigt vetenskapligt/konstnärligt) abstract
Inom den regenerativa medicinen strävar man efter att ersätta skadat eller sjukligt biologiskt mänskligt material (celler, organ, kroppsdelar) med nya biologiska komponenter. Området aktualiserar en rad etiska frågeställningar vad gäller (1) produktionen av ersättningsmaterialet (t.ex. embryonala stamceller eller införskaffande av transplantationsvävnad från donatorer), (2) risker i samband med försök på människa (genmodifierat material, material från djur), samt (3) gränserna för hur långt man bör gå i denna slags försök att förlänga människans livsspann. Föredraget ger en kort översikt över dessa frågeställningar, ståndpunkter och argument i debatten kring dem.
5.
Chenna Narendra, Sudeep
(författare)
Systemic and local regulation of experimental arthritis by IFN-α, dendritic cells and uridine
2017
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
In this thesis, we have studied the immunological processes of joint inflammation that may be targets for future treatment of patients with arthritis. We focus on the immune-modulating properties of interferon-α (IFN-α) and uridine in experimental arthritis. The nucleoside uridine, which is regarded a safe treatment has anti-inflammatory properties notably by inhibiting tumor necrosis factor (TNF) release. Because the inflamed synovium in rheumatoid arthritis (RA) is characterised by pathogenic TNF-production, uridine could potentially be away to ameliorate arthritis. Systemic administration of uridine had no effect on antigeninduced arthritis (AIA), which is a T-cell dependent model where animals are immunized twice (sensitization) with bovine serum albumin (mBSA), before local triggering of arthritis by intra-articular antigen (mBSA) re-challenge. In contrast, intra-articular administration of uridine clearly down modulated development of AIA in a dose dependent manner and inhibited the expression of synovial adhesion molecules, influx of inflammatory leukocytes and synovial expression of TNF and interleukin 6, but did not affect systemic levels of proinflammatory cytokines or antigen-specific T-cell responses. Local administration of uridine may thus be a viable therapeutic option for treatment of arthritis in the future.Viral double-stranded deoxyribonucleic acid (dsRNA), a common nucleic acid found in most viruses, can be found in the joints of RA patients and local deposition of such viral dsRNA induces arthritis by activating IFN-α. Here we show that arthritis induced by dsRNA can be mediated by IFN-producing dendritic cells in the joint and this may thus explain why viral infections are sometimes associated with arthritis.Earlier, to study the effect of dsRNA and IFN-α in an arthritis model, that like RA, is dependent on adaptive immunity, dsRNA and IFN-α were administered individually during the development of AIA. Both molecules clearly protected against AIA in a type I IFN receptor-dependent manner but were only effective if administered in the sensitization phase of AIA. Here we show that the anti-inflammatory effect of IFN-α is critically dependent on signalling via transforming growth factor β (TGF-β) and the enzymatic activity of indoleamine 2,3 dioxygenase 1 (IDO). The IDO enzyme is produced by plasmacytoid DC and this cell type was critically required both during antigen sensitization and in the arthritis phase of AIA for the protective effect of IFN-α against AIA. In contrast, TGF-β and the enzymatic activity of IDO were only required during sensitization, which indicate that they are involved in initial steps of tolerogenic antigen sensitization. In this scenario, IFN- α first activates the enzymatic activity of IDO in pDC, which converts Tryptophan to Kynurenine, which thereafter activates TGF-β. Common for IDO-expressing pDC, Kyn and TGF-β is their ability to induce development of regulatory T cells (Tregs). We found that Tregs were crucial for IFN-α-mediated protection against AIA, but only in the arthritis phase. In line with this, adoptive transfer of Tregs isolated from IFN-α treated mice to recipient animals in the arthritis phase clearly protected against AIA. The numbers of Tregs were not significantly altered by IFN-α but IFN-α increased the suppressive capacity of Tregs against antigen-induced proliferation. This enhanced suppressive activity of Tregs in the arthritis phase was dependent on the earlier activated enzyme IDO1 during the sensitization phase of AIA. Thus, presence of IFN-α at the time of antigen sensitization activates the enzymatic activity of IDO, which generates Tregs with enhanced suppressive capacity that upon antigen re-challenge prevents inflammation. We have thus identified one example of how immune tolerance can be developed, that may be a future way to combat autoimmunity.
6.
Düringer, Caroline, et al.
(författare)
HAMLET; a novel tool to identify apoptotic pathways in tumor cells.
2005
Ingår i: Application of apoptosis to cancer treatment.. - Berlin/Heidelberg : Springer-Verlag. - 9781402033032 ; , s. 223-245
Bokkapitel (övrigt vetenskapligt/konstnärligt) abstract
Tumor cells often carry mutations in genes that control cell survival, and become resistant to signals that trigger cell death. Yet, some cell death pathways remain intact in tumor cells. If identified, these pathways might be exploited to selectively remove tumor cells. HAMLET (human α-lactalbumin made lethal to tumor cells) is a protein-lipid complex derived from human milk that activates cell death programs in tumor cells but not in healthy differentiated cells. We use HAMLET as a tool to identify apoptosis and apoptosis-like cell death mechanisms in tumor cells and to understand if these mechanisms differ between tumor and healthy cells. HAMLET interacts with the cell surface, translocates into the cytoplasm and accumulates in cell nuclei, where it disrupts the chromatin. Recent in vivo studies have shown that HAMLET maintains the tumoricidal activity in glioblastoma, papilloma and bladder cancer models, with no significant side effects. The results suggest that HAMLET should be explored as a new therapeutic agent with selectivity for the tumor and with little toxicity for adjacent healthy tissue. Such therapies are a much-needed complement to conventional treatments, to reduce the side effects and improve the selectivity.
7.
Heyman, Lovisa
(författare)
Berries in Prevention of Metabolic Disease – focus on obesity, diabetes and gut microbiota
2015
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
The increasing prevalence of obesity is a worldwide health problem closely linked to diet and lifestyle factors. Obesity is associated with increased risk of several metabolic disorders including insulin resistance, nonalcoholic fatty liver disease and type 2 diabetes. Hence, there is a great need to identify dietary strategies for the prevention of obesity and related diseases. This thesis investigates the potential of different berries to mediate beneficial health effects in a mouse model of diet-induced obesity and prediabetes. We found that supplementation with lingonberries, blackcurrants and bilberries reduced body weight gain, insulin resistance, low-grade inflammation and hepatic lipid accumulation in C57BL/6J mice fed a high-fat diet. Supplementation with raspberries, crowberries, blackberries or prunes had no or small effects, whereas açai berries promoted development of obesity and fatty liver compared to the control group receiving high-fat diet without berries. Global hepatic gene expression analysis revealed that the phenotype in the lingonberry and bilberry groups was coupled to an anti-inflammatory effect, including downregulation of acute-phase proteins and inflammatory mediators. Mice receiving açai displayed an upregulation of steatosis markers and genes related to lipid synthesis, in line with the exacerbation of high-fat-induced fatty liver in these mice. The HELP-tagging assay was used to identify differentially methylated CpG sites in the lingonberry group compared to the high-fat control group. Lingonberries induced genome-wide and specific alterations of DNA methylation, however the significance of these findings remains to be established. Furthermore, different batches of lingonberries were found to have different capacity to prevent obesity. However lingonberries prevented low-grade inflammation, metabolic endotoxemia and modified the gut microbiota of high-fat fed mice, including increasing the Firmicutes/Bacteroidetes ratio. These findings were independent of effects on body weight gain and achieved regardless of the source of berries. The capacity of lingonberries to counteract negative outcomes of an unhealthy diet should be further evaluated in humans, including assessment of anti-inflammation and microbiota modulation. The generated knowledge about berries and their effects on metabolism may be useful in designing future dietary strategies aimed at preventing metabolic disease.
8.
9.
Skoog, Emma C, 1983
(författare)
Helicobacter spp. interactions with mucins: adhesion and mucin regulation of pathogen proliferation and gene expression
2014
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Helicobacter pylori colonizes the gastric mucosa of approximately half of the world’s population and is a risk factor for gastritis, peptic ulcers and gastric cancer. H. pylori is surrounded by, and adheres to, the heavily glycosylated mucins that build up the mucus layer. The carbohydrate structures on the mucins that act as ligands for H. pylori vary between individuals and change during disease. In this thesis, we investigated how H. pylori interacts with differently glycosylated mucins by analyzing adhesion, proliferation, gene expression and the resulting effect on virulence to host cells. We found that mucins can interfere with H. pylori proliferation, partly dependent on binding to the mucins and the presence of known antimicrobial structures, but also observed an inhibition of H. pylori proliferation independent of these two factors. The gene expression of H. pylori varied greatly in the response to differently glycosylated mucins. Expression of the virulence factor CagA increased in response to some mucins, presumably by Fur-dependent regulation as a result of binding via the SabA adhesin. The varying interaction of H. pylori and mucins resulted in alterations in the response of infected gastric epithelial cells in vitro. There are several Helicobacter species that commonly infects other animals, but can also infect and cause disease in humans. Their modes of interaction with mucins are unclear. We examined the adhesion of two non-H. pylori Helicobacter species to differently glycosylated gastric mucins and mucosal tissue from a range of animals. Our results demonstrated that they can adhere to mucins and gastric tissue via specific glycan structures that change during infection, although the binding ability to human mucins are lower than that of H. pylori. In addition, there are other bacteria in the stomach that may interfere with mucin interactions of Helicobacter spp. We showed that Lactobacillus species isolated from the same stomachs as H. pylori did not compete for the same mucin ligands and did not markedly change how co-isolated H. pylori interact with the mucins. In summary, H. pylori adhesion to human mucins differs from that of other Helicobacter spp. and is not affected by co-colonizing Lactobacillus spp. The interactions of H. pylori to mucins affect proliferation and expression of virulence factors that may influence the colonization ability, virulence and host response and ultimately play a role in the development of symptoms displayed in the host.
10.
Wilms, Torben, 1973-
(författare)
Squamous cell carcinoma of the head and neck, focusing on Epstein-Barr-virus, programmed cell death ligand 1 and serum lipoproteins
2021
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Background: Squamous cell carcinoma of the head and neck (SCCHN)comprises a large group of tumours including the oral cavity and nasopharyngealarea, and typically affects older males in association with alcohol/tobacco usage.Within the oral cavity, the mobile tongue is the most common site for tumourdevelopment. The incidence of squamous cell carcinoma of the oral tongue(SCCOT) is increasing in younger people, which has been suggested to associatewith other than the traditional risk factors for this disease. Two common humanoncogenic viruses, human papillomavirus (HPV) and Epstein-Barr virus (EBV)are connected to certain types of SCCHN, in oropharynx and nasopharynxrespectively. The receptor programmed cell death 1 (PD)-1 and its ligandprogrammed cell death ligand 1 (PD-L1) are particularly relevant in immunecheckpoint control, and elevated levels have been seen in various cancer types. Alink between hyperlipidemia and cancer risk has previously been suggested. Theaim of this thesis was to investigate risk factors and prognostic features forSCCHN, by focusing on EBV, PD-L1 and serum lipoproteins.Materials and methods: Ninety-eight cases of SCCOT and 15 cases of tonsillarsquamous cell carcinoma were examined for the presence of EBV-encodedribonucleic acids (EBERs), EBV deoxyribonucleic acid (DNA) and the proteinEBV-encoded nuclear antigen-1 (EBNA-1), using in situ hybridisation,polymerase chain reaction (PCR) and immunohistochemistry respectively. Onehundred and one cases of SCCOT were examined for expression of PD-L1 intumour and surrounding immune cells using Ventana SP263immunohistochemistry assay and a QuickScore (QS) method. An estimation oftumour-infiltrating immune cells was also performed in 25 of the patients.Circulating levels of PD-L1 were measured using an electrochemiluminescenceassay platform in serum from 30 patients. Finally, serum samples from 106patients and 28 healthy controls were investigated for levels of total cholesterol,low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides andlipoprotein(a).Results: In the first study, using an in situ hybridisation kit no EBER transcriptswere detected. No EBV DNA was identified with PCR analysis, andimmunohistochemistry for EBNA-1 was also negative. In the second study, highertumour cell PD-L1 levels were found in females than males (p = 0.019). Forpatients with low PD-L1 in tumour cells, better survival was shown in males thanfemales (overall survival p = 0.021, disease-free survival p = 0.020). Tumourinfiltrating natural killer (NK) T cells, immature dendritic cells (DCs) and M1macrophages correlated positively with tumour cell PD-L1 (p < 0.05). In the laststudy, the only lipoprotein showing significant difference in concentration iiibetween healthy controls and patients was HDL (p = 0.012). Kaplan-Meiersurvival curves showed that patients with high levels of total cholesterol or LDLhad better survival than patients with normal levels (p = 0.028 and p = 0.007respectively). Adjusting for the effects of age at diagnosis, TNM stage and weightchange, multivariate Cox regression models showed LDL to be an independentprognostic factor for both overall (p = 0.010) and disease-free survival (p =0.018).Conclusion: We excluded EBV as a potential player in SCCOT in both old andyoung patients and highlight the importance of appropriate controls for EBVencoded RNA in-situ hybridization (EBER-ISH) when investigating EBV inhuman diseases. Regarding PD-L1, our data supported the significance of genderon tumour cell PD-L1 expression and demonstrated combined effects of genderand PD-L1 levels on clinical outcome in patients with SCCOT. Data also indicatedthe involvement of specific immune cell types in PD-L1-regulated immuneevasion. Looking at serum lipoproteins, we found high LDL levels to be beneficialfor survival outcome in patients with SCCHN. Furthermore, the use of cholesterollowering medicine for prevention or management of SCCHN needs to be carefullyevaluated.
