Abstract The purpose of this study was to develop sensitive and specific laboratory diagnostic methods for the demonstration of pneumococcal surface antigens or pneumococcus-specific antibodies in clinical samples. The work took account of epidemiological aspects of both pneumococcal disease and nasopharyngeal carriage of pneumococcus. We first compared the sensitivity of pneumococcal culture and antigen detection methods in nasopharyngeal samples in a developing country setting and then investigated the possibility of improving the sensitivity of the antigen detection by introducing an enrichment step in the procedure. — Further investigations were designed to determine the validity of pneumolysin-specific immune complex bound antibody assay as a tool for diagnosing pneumococcal ALRI in a developing country setting. Finally, we developed an enzyme immunoassay for the detection of pneumococcal capsular polysaccharide antigens, using type-specific antibodies produced in-house in rabbits through immunisation with an in-house-produced pneumococcal whole cell vaccine. The method was tested in nasopharyngeal and middle ear fluid samples. The first results indicated that antigen detection might be more sensitive than culture in demonstrating pneumococci in URT, particularly in children with prior antimicrobial therapy. Antigen detection is a feasible method for studies on pneumococci in developing countries. For type-specific demonstration of S. pneumoniae, detection of pneumococcal antigen after an enrichment step proved a sensitive method that can be applied for epidemiologic study purposes, e.g., in vaccine trials, in areas without ready access to a good microbiology laboratory. Determination of IC-bound pneumolysin IgG antibodies appears to be a useful method for species-specific diagnosis of pneumococcal infections. The results indicating pneumococcal aetiology in ALRI patients in this study compare well with the best results obtained by the use of lung aspirates. Increasing the number of serial samples improves the sensitivity of the assay, but even two samples provide more positive findings than other methods currently in routine use. Criteria of positivity need to be confirmed in subsequent larger studies with both healthy controls and patients with confirmed pneumococcal disease. It is also important to control the findings in patients with pneumonia of non-pneumococcal origin. The novel enzyme immunoassay was shown to work well with enrichment culture samples, with an almost 100% sensitivity compared with the culture. Middle ear fluid samples were too diluted for the enzyme immunoassay method used, and only 74% sensitivity compared with culture was achieved. Provided that adequate samples can be obtained, the method will be a useful complement to the current laboratory methods used to diagnose pneumococcal disease. With the existence of a broad spectrum of microbiological and immunological methods, it is imperative to seek international consensus for standard methods to demonstrate pneumococcus. Otherwise it is very difficult to compare results from different clinical studies. A WHO Working Group recently proposed a standard method for detecting upper respiratory carriage of pneumococcus, but a lot of work remains to be done in other areas of research on pneumococcal infections.

Abstract Streptococcus pneumoniae, pneumococcus, is a common cause of respiratory tract infections and also a common inhabitant of the upper respiratory tract of healthy people. At present, 93 different polysaccharide types have been identified and in addition to them, unencapsulated pneumococci are found especially in healthy carriers. Pneumococci are usually identified by using a bacterial culture combined with biochemical or immunochemical tests. Recently, new DNA-based methods, such as PCR, have been applied. Many PCR methods that detect pneumococci are targeted at genes which encode virulence factors such as pneumolysin, autolysin and pneumococcal surface antigen A. S. pneumoniae is a common causative agent of otitis media. In clinical trials, xylitol has been shown to decrease the occurrence of otitis media but the mechanism of action is not known. Xylitol has been shown to reduce pneumococcal growth and adherence to nasopharyngeal cells and its effect on the appearance of the pneumococcal polysaccharide structure has been shown by electron microscopy. Xylitol has also been demonstrated to inhibit biofilm formation of Staphylococcus aureus and Pseudomonas aeruginosa. Biofilms have been associated with otitis media and pneumococci have been shown to form biofilms. The purpose of this work was to study the role of capsular and other virulence genes in pneumococcal infection and biofilm formation. A new PCR method was developed to detect the pneumococcal capsule and it appeared to have potential when studying the pneumococcal etiology of pneumonia. Widely used PCR methods were used to study pneumococcal isolates, and conflicting results were obtained when the results were compared with conventional immunochemical methods. In addition, xylitol was shown to inhibit capsular gene expression and biofilm formation of pneumococci. Glucose and fructose appeared to enhance biofilm formation. The conflicting results between PCR and immunochemical methods suggest that further identification methods are needed in the diagnosis of pneumococcal infection. The observed inhibitory effect of xylitol on pneumococcal capsule gene expression and biofilm formation may partly explain the efficacy of xylitol in preventing acute otitis media in previous clinical trials. / Tiivistelmä Streptococcus pneumoniae, pneumokokki, on yleinen hengitystieinfektioiden aiheuttaja, joka esiintyy myös hengitysteiden normaalifloorassa. Pneumokokilla tunnetaan 93 kapselityyppiä ja näiden lisäksi etenkin oireettomilta nielukantajilta löytyy kapselittomia pneumokokkeja. Pneumokokin tunnistamiseen käytetään yleensä viljelyä sekä bio- ja immunokemiallisia testejä ja sittemmin tunnistuksen tukena on käytetty geeniteknologisia menetelmiä, kuten PCR. Useissa pneumokokin tunnistuksessa käytettävissä PCR-menetelmissä on käytetty kohdegeeninä virulenssitekijöitä, kuten pneumolysiiniä, autolysiinia ja pneumokokin pinta-antigeeni A:ta koodaavia geenejä. Pneumokokki on yleinen korvatulehdusten aiheuttaja. Kliinisissä tutkimuksissa ksylitolin on havaittu vähentävän korvatulehduksia, mutta vaikutusmekanismi on vielä epäselvä. Ksylitolin on osoitettu vähentävän pneumokokin kasvua ja kiinnittymistä nenänielun soluihin ja sen vaikutus polysakkaridikapselin ulkomuotoon on osoitettu elektronimikroskopialla. Ksylitolin on myös todettu vähentävän biofilminmuodostusta Staphylococcus aureus, ja Pseudomonas aeruginosa –bakteereilla. Biofilmin muodostuksen on ehdotettu liittyvän krooniseen korvatulehdukseen. Aiemmissa tutkimuksissa pneumokokin on osoitettu muodostavan biofilmejä. Työn tarkoituksena oli tutkia kapseli- ja muiden virulenssigeenien merkitystä pneumokokki-infektion diagnostiikassa ja biofilminmuodostuksessa. Työssä kehitettiin uusi PCR-menetelmä pneumokokin kapselin osoittamiseksi ja sillä todettiin olevan käyttömahdollisuuksia keuhkokuumeen pneumokokkietiologiaa tutkittaessa. Yleisesti käytettyjä PCR-menetelmiä tutkittiin pneumokokki-isolaateilla ja havaittiin vakavia ristiriitoja näiden ja perinteisten, immunokemiallisten tunnistusmenetelmien välillä. Lisäksi tutkimuksessa havaittiin ksylitolin vähentävän pneumokokin kapseligeenien ekspressiota ja biofilmin muodostusta. Sen sijaan glukoosi ja fruktoosi lisäsivät biofilmin muodostusta. Tutkimustulokset osoittivat ristiriidan perinteisten immunokemiallisten ja PCR-menetelmien välillä ja antavat aihetta uusien, tarkempien menetelmien käyttöönotolle pneumokokki-infektion diagnostiikassa. Tutkimuksen havainnot ksylitolin vaikutuksesta pneumokokin kapseligeeniekspressioon ja biofilmin muodostukseen voivat osittain selittää kliinisissä tutkimuksissa havaittua ksylitolin ehkäisevää vaikutusta korvatulehduksiin.

Protein phosphorylation by protein kinases is a key mechanizm that enables both eukaryotic and prokaryotic organizm sense and read environmental signals and convert these signals into changes in gene expression and thus proper biological response. One of the main phosphorylation systems in bacteria consists of eukaryotic-like Ser/ Thr protein kinases. The genome of human pathogen Streptococcus pneumoniae contains single Ser/ Thr protein kinase StkP. StkP regulates virulence, competence, stress resistance, gene expression and plays an important role in the regulation of cell division cycle. Analysis of phosphoproteome maps of both wild type and ΔstkP mutant strain of S. pneumoniae showed that in vivo StkP phosphorylates several putative substrates including the cell division protein DivIVA (NOVÁKOVÁ et al., 2010). DivIVA in S. pneumoniae is localized at midcell and at the cell poles. It was proposed to be primarily involved in the formation and maturation of the cell poles (FADDA et al., 2007). The aim of this thesis was to investigate phosphorylation of the cell division protein DivIVA in S. pneumoniae. Gene divIVA was cloned, expressed in E. coli and protein was purified via affinity chromatography. Phosphorylation of DivIVA by StkP was examined in a kinase assay. We confirmed that DivIVA is a direct...

C-reactive protein (CRP) is a part of the innate immune system, is synthesized in the liver, its blood level increases in inflammatory states, and it binds to Streptococcus pneumoniae. The conformation of CRP is altered under conditions mimicking an inflammatory milieu and this non-native CRP also binds to immobilized/aggregated/pathogenic proteins. Experiments in mice have revealed that one of the functions of CRP is to protect against pneumococcal infection. For protection, CRP must be injected into mice within two hours of administering pneumococci, thus, CRP is protective against early-stage infection but not against late-stage infection. It is unknown how CRP protects or why CRP does not protect against late-stage infection. The hypotheses are that the protection requires complement activation by CRP-pneumococci complexes and that CRP cannot protect if pneumococci have time to recruit complement inhibitor factor H on their surface to become complement attack-resistant. To test these hypotheses, we generated CRP mutants by site-directed mutagenesis: a mutant that binds to pneumococci but does not activate complement and a mutant that binds to immobilized factor H. We found that mutant CRP incapable of activating complement was not protective against infection and that mutant CRP capable of binding to factor H was protective against both early and late stage infections. Additional experiments showed that CRP enhances the effects of the antibiotic clarithromycin in reducing bacteremia in infected mice. Moreover, we observed that mutant CRP capable of binding to factor H bound to several proteins immobilized on plastic, suggesting that CRP recognizes a pattern, probably an amyloid-like structure, on immobilized proteins. Indeed, mutant CRP, after binding to amyloid b peptides, prevented the formation of pathogenic amyloid fibrils. Lastly, employing a hepatic cell line, we investigated the mechanism of CRP expression in response to pro-inflammatory cytokines. We found that the transcription factor C/EBPb and two C/EBP-binding sites on the CRP promoter were critical for inducing CRP expression. We conclude that complement activation is necessary for CRP-mediated protection against infection, that CRP functions in two structural conformations, that CRP and clarithromycin act synergistically, that CRP has anti-amyloidogenic properties, and the increased CRP expression requires C/EBPb.

Streptococcus pneumoniae (S. pneumoniae) is a Gram-positive, encapsulated bacterium capable of causing significant morbidity and mortality throughout the world. A hallmark of S. pneumoniae infection is infiltration of neutrophils (PMNs) that assist in controlling the spread infection but may also contribute to pathology. Paradoxically, studies have shown that limiting PMN infiltration into the lumen of the lung during infection actually betters clinical outcome in experimental S. pneumoniae infection. The final step in PMN luminal trafficking is a Hepoxilin A3 (HXA3)-dependent migration across the pulmonary epithelium. HXA3 is a PMN chemoattractant that forms gradients along the polarized epithelial face, drawing PMNs from the basolateral to the apical surface during proinflammatory responses. HXA3 requires assistance of an integral- membrane protein transporter to escape the cell and form the gradient. The pulmonary HXA3 transporter is currently unidentified. In this work, we identify the pulmonary HXA3 transporter as the ATP-Binding Cassette Transporter (ABC transporter) Multi-drug Resistance Associated Protein 2 (ABCC2, MRP2). We demonstrate that MRP1 and MRP2 are divergent ABC- transporters that control transepithelial PMN migration through efflux of a distinct anti-inflammatory substance and the pro-inflammatory HXA3 in the context of Streptococcus pneumoniae infection. Enrichment of MRP2 on the plasma membrane requires detection of the bacterial virulence factors pneumolysin (PLY) and hydrogen peroxide. PLY and hydrogen peroxide not only coordinate MRP2 apical membrane enrichment but also influence HXA3-dependent PMN transepithelial migration. They influence migration through stimulation of epithelial intracellular calcium increases that are crucial for HXA3 production as well as MRP2 translocation to the plasma membrane. PLY and hydrogen peroxide are not sufficient in their signaling alone, however, and require at least one additional bacterial signal to induce HXA3/MRP2 proinflammatory activities.

Maternal obesity has significant consequences on the lifelong health of the developing child and rising global incidences make it one of the most common comorbidities during pregnancy. Offspring of obese mothers are at an increased risk of hospitalization for respiratory infections throughout childhood, which predispose these children to non-communicable respiratory diseases in later life. Animal models of maternal high fat diet (mHFD) feeding have observed common inflammatory outcomes with obesogenic models, but the effect on offspring varies with timing of the nutritional challenge and diet composition across studies. These studies demonstrate significant alterations to circulating and lung specific immune cells but the sequence of events that link maternal diet to these fetal outcomes are unclear, nor have they been tested in the context of a bacterial respiratory infection. Streptococcus pneumonaie is the most common causative pathogen of bacterial pneumonia and meningitis, making it of high clinical relevance. We aimed to investigate the effect of a mHFD (45% kcal from fat) during gestation and lactation, on offspring outcome and recovery from Streptococcus pneumoniae infection. Immunophenotyping, both before and after infection, revealed a hypo-inflammatory phenotype in circulating monocytes of the mHFD offspring with a decreased capacity to both initiate and terminate inflammatory responses. These offspring had significantly higher bacterial counts in lung tissues during infection and sustained cellular inflammation in survivors. In this thesis, we present foundational work on the detrimental influence of excess maternal nutrition on offspring immune function and infection outcomes, which may be involved in susceptibility to inflammatory and chronic disease in later life. A better understanding of this deep and lasting influence of the maternal environment will allow us to target preconception health as a form of harm reduction, informing stake holders and institutions to direct efforts towards DOHaD knowledge translation. / Thesis / Master of Science (MSc)

No description available.

Colonization is prerequisite for infection and transmission of Streptococcus pneumoniae, or pneumococcus. Currently available pneumococcal conjugate and pneumococcal polysaccharide vaccines can provide protection against a limited number of capsular serotypes. Implementation of vaccines has decreased the frequency of invasive pneumococcal disease and their colonization rates, but only in a serotype-dependent manner. This has led to serotype replacement in pneumococcal ecology and increased invasive disease caused by non-vaccine serotypes. Development of conserved protein-based vaccine that can provide protection against all pneumococcal serotypes is needed. Numerous surface proteins are conserved in all serotypes, and some are known to be involved in the colonization process. Understanding how pneumococcal surface proteins interact with host cells and determining their roles in colonization will aid in vaccine development. In this dissertation, we characterized host cell receptors of pneumococcal surface proteins, and proteins involved in biofilm formation, and their effect in colonization. We utilized a novel protein expression vector, pOS1, which can express secreted proteins with no LPS, IPTG induction, or cell lysis requirement. These expressed recombinant proteins were used for further investigation. We identified that human Annexin A2 (ANXA2) interacts with pneumococcal surface adhesion A (PsaA) protein. ANXA2 transduced cells showed significant increase in binding with pneumococcus compared to non-transduced cells. We conducted proteomic profiling of planktonic and biofilm membrane proteins and identified that two lipoproteins (AmiA, SP_0148) were overexpressed during biofilm formation. Isogenic mutants lacking these individual proteins showed decreased in biofilm formation compared to their parental strain. Deletion of SP_0148 led to decreased adhesion of pneumococcus to human nasopharyngeal epithelial cells (Detroit 562). These results increased our understanding of pneumococcal surface proteins involved in biofilm-formation and colonization as well as identifying new host receptors ligands for these adhesins.

The bacterium Streptococcus pneumoniae (pneumococcus), is considered to be a leading cause of morbidity and mortality globally, particularly in infants and the elderly. It is one of the most frequent causes of respiratory tract infections, which sporadically have the potential to develop into serious invasive symptoms including sepsis and meningitis. The development of effective vaccination against this pathogen is essential for reducing the morbidity and mortality it causes since the currently available vaccines can protect against only a limited number of the 100 pneumococci serotypes which target the polysaccharidic capsule of the bacterium. The potential use of conserved protein antigens could provide a defense to a wider range of serotypes and clonal types. The immunogenic properties of the proteins MalX and PrsA as well as their role in vital biological functions of S. pneumoniae have made them stand out as potential targets. MalX is a crucial membrane protein involved in the metabolism of maltose, whereas PrsA is a chaperone-like protein that is connected to the cell envelope. To understand these proteins' potential as vaccine candidates, it is essential to understand their immunogenic characteristics and physiological roles. In this project, we tried to characterize the two antigens to determine the functional significance of different regions and domains in antigen recognition and their expression dynamics in bacterial host. A better understanding of the antigenic properties of the PrsA and MalX proteins will drive the construction of improved versions of antigens for vaccine prototypes. Some approaches were used to clarify the structural characteristics and antigenic determinants associated with these proteins including, protein expression, purification, and structural characterization. Additionally, their expression in E. coli was examined using immunological assays including ELISA and Western blot. The identification of antigenic regions of these proteins also provides insight into how to develop epitope-based vaccinations that specifically target S. pneumoniae. This project discusses the possibility of using membrane vesicles (MVs) as a platform for vaccination. Membrane vesicles made from bacterial cells have innate immunogenic qualities that expose the immune system to a wide variety of antigens. Incorporating MalX and PrsA into such vesicles can improve the vaccine candidate's overall immunogenicity and effectiveness and trigger a stronger immune response against S. pneumoniae.

The transcription factor Krueppel-like factor (KLF) 4 fosters the pro-inflammatory immune response in macrophages and polymorphonuclear neutrophils (PMNs) when stimulated with Streptococcus pneumoniae, the main causative pathogen of community-acquired pneumonia (CAP). Here, we investigated the impact of KLF4 expression in myeloid cells such as macrophages and PMNs on inflammatory response and disease severity in a pneumococcal pneumonia mouse model and in patients admitted to hospital with CAP. We found that mice with a myeloid-specific knockout of KLF4 mount an insufficient early immune response with reduced levels of pro-inflammatory cytokines and increased levels of the anti-inflammatory cytokine interleukin (IL) 10 in bronchoalveolar lavage fluid and plasma and an impaired bacterial clearance from the lungs 24 hours after infection with S. pneumoniae. This results in higher rates of bacteremia, increased lung tissue damage, more severe symptoms of infection and reduced survival. Higher KLF4 gene expression levels in the peripheral blood of patients with CAP at hospital admission correlate with a favourable clinical presentation (lower sequential organ failure assessment (SOFA) score), lower serum levels of IL-10 at admission, shorter hospital stay and lower mortality or requirement of intensive care unit treatment within 28 days after admission. Thus, KLF4 in myeloid cells such as macrophages and PMNs is an important regulator of the early proinflammatory immune response and, therefore, a potentially interesting target for therapeutic interventions in pneumococcal pneumonia.