Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries. The Y402H polymorphism in complement factor H (CFH) is a common and important risk factor, where CFH is an inhibitor of the alternative complement pathway. The disease-associated protein variant (CFH402H) binds poorly to aged human macular Bruch’s membrane (BM), a site of AMD formation. Heparan sulphate (HS) is the major binding site for CFH in this extracellular matrix. Unlike CFH402Y, CFH402H binds poorly to lowly sulphated HS. The aim of this research was to investigate the presence and distribution of proteoglycan (PG) core proteins and glycosaminoglycans (GAGs) in the normal adult human macula, and to analyse potential changes with age in the quantity and composition of HS and other potential molecular determinants of disease in BM. Post mortem human eye tissue was obtained from consenting donors (age range 18-93 years), and either dissected into tissue layers or used to produce frozen macular tissue sections. Proteomic analysis of different retinal tissue layers was performed by tandem mass spectrometry. Immunofluorescence microscopy was undertaken on the macular tissue sections. Compositional analysis of HS in BM was performed by 2-aminoacridone labelling of HS disaccharides and reverse phase high performance liquid chromatography against reference HS disaccharide standards. PG core proteins were identified in BM and other macular tissue layers, including members of the basement membrane, hyalectan and short leucine-rich repeat PG families. HS, chondroitin sulphate, dermatan sulphate and hyaluronan were present throughout the retina and choroid, but keratan sulphate only in the sclera. The mean quantity of HS in BM was 47% lower (p=0.006) in old donors (n=13, 64-92 years), compared to young donors (n=6; 26-39 years). The mean level of HS sulphation was also lower in old donors, e.g. 34% vs. 39% (p=0.02) N-sulphated HS. The mean level of HS in macular BM by immunohistochemistry was approximately 50% lower (p=0.02) in old donors (n=10, 18-93 years), and the mean level of the HS PG core protein perlecan was reduced by 85% (p=0.01; n=18, 27-90 years). High levels of complement activation (C3b and membrane attack complex) were observed in some young donors. Reduced HS was associated with increased complement activation in some donors (r2 0.30). A combination of proteomics and immunohistochemistry approaches has provided the first comprehensive analysis of the presence and distribution of PG core proteins and their associated GAG chains throughout the macular layers of the normal adult human retina. These demonstrate a differential distribution according to PG core protein, GAG class and GAG sulphation state. The quantity of HS decreases substantially with age in human BM, and its sulphation level also decreases. The presence of less HS in old BM would make fewer binding sites available for CFH, and could contribute to AMD pathogenesis through increased complement activation. This idea is supported by the observation that reduced HS is associated in some individuals with increased C3b in BM. These findings have important implications for unravelling mechanisms of ocular disease and planning novel therapeutic strategies, particularly in the case of AMD.

No description available.

C1QTNF5 is a 25kDa short chain collagen of unknown function which is mutated in late-onset retinal macular degeneration (L-ORMD). L-ORMD is an autosomal dominant disease characterised by sub-retinal pigment epithelial deposits leading to photoreceptor death and visual loss and shows several similarities to age-related macular degeneration (AMD). A Tyr402His polymorphism in complement factor H (CFH), a regulatory protein in the innate immune system, has been associated with increased risk of AMD. C1QTNF5 and CFH are both expressed and secreted by the retinal pigment epithelium (RPE) which supports photoreceptors and is responsible for phagocytosis of shed rod photoreceptor outer segments (ROS). The properties of the normal C1QTNF5 and disease-associated Ser163Arg mutation were examined in detail, including protein characterisation, cellular processing and function. Recombinant wild type and mutant C1QTNF5 were produced and their multimerisation and solubility functions compared. Both proteins were found to be soluble and to form similar multimeric species which were resistant to reducing conditions, as seen in other short chain collagens. Due to the similarities between LORMD and AMD, a proposed interaction between C1QTNF5 and CFH was investigated. CFH is composed of 20 short consensus repeats (SCR) and interactions were confirmed between C1QTNF5 and both CFH and SCR modules 7-8 and 19-20. CFH showed a greater affinity for mutant C1QTNF5 compared with wild type on the basis of surface plasmon resonance assays. Stably transfected RPE-derived cell lines were created which expressed either wild type or mutant C1QTNF5. Both proteins were found to be secreted and showed similar cellular processing with no evidence of aggregation or retention of the mutant protein within the endoplasmic reticulum. In order to investigate C1QTNF5 function, phagocytosis of ROS by the stably transfected cell lines was carried out. Cells expressing wild type C1QTNF5 showed greater ROS phagocytosis compared with mutant C1QTNF5-expressing or untransfected cells. Addition of anti-C1QTNF5 antibody increased ROS phagocytosis further. In summary, it is proposed that wild type and mutant C1QTNF5 are secreted by the RPE where they interact with CFH. C1QTNF5 is also shown to have a role in ROS phagocytosis, with mutation in C1QTNF5 affecting phagocytosis efficiency, which may contribute to sub-RPE deposit formation. The results suggest that CFH may also be involved in this process, suggesting a common pathogenic pathway between L-ORMD and AMD.

Analysis and characterisation of biomolecules using mass spectrometry has advanced over the past decade due to improvements in instrument design and capability; relevant use of complementary techniques; and available experimental and in silico data for comparison with cutting-edge research. This thesis presents ion mobility data, collected on an in-house modified QToF mass spectrometer (the MoQTOF), for a number of protein systems. Two haemoproteins, cytochrome c and haemoglobin, have been characterised and rotationally-averaged collision cross-sections for a number of multimeric species are presented. Intact multiply-charged multimers of the form [xCyt c + nH]z+ where x = 1 (monomer), x = 2 (dimer) and x = 3 (trimer) for cytochrome c have been elucidated and for species with x ≥ 2, reported for the first time. Fragment ions possibly attributed to a novel fragmentation mechanism, native electron capture dissociation, are reported with a brief discussion into their possible production from the dissociation of the gas-phase dimer species. Haemoglobin monomer globin subunits, dimers and intact tetramer have been successfully transferred to the gas phase, and their cross-sections elucidated. Comparisons with in silico computational data have been made and a discussion of the biologically-active tetramer association/dissociation technique is presented. Three further proteins have been studied and their gas-phase collision cross-sections calculated. Two regions of the large Factor H (fH) complement glycoprotein, fH 10-15 and fH 19-20, have been characterised for the first time by ion mobility-mass spectrometry. Much work using nuclear magnetic resonance spectroscopy has previously been achieved to produce structural information of these protein regions, however further biophysical characterisation using mass spectrometry may aid in greater understanding of the interactions these two specific regions have with other biomolecules. The DNA-binding core domain of the tumour suppressor p53 has been characterised and cross-sections produced in the presence and absence of the zinc metal ion that may control the domain’s biological activity. Within this core domain, p53 inactivation mutations have been shown to occur in up to 50% of human cancers, therefore the potential exists to further cancer-fighting activity through research on this region. Anterior Gradient-2 (AGR2) protein facilitates downregulation of p53 in an as yet unclear mechanism. Recent work using peptide aptamers has demonstrated that this downregulation can be disrupted and levels of p53 restored. Collision cross-sections for six peptide aptamers have been calculated, as well as cross-sections for multimers of AGR2 protein. A complex between one aptamer with the protein has also been elucidated. Use of the commercially available Synapt HDMS ion mobility-mass spectrometer at Waters MS Technologies Centre (Manchester, UK) allowed data to be collected for both Factor H protein regions and for the DNA-binding core domain of p53. Data are compared in the appropriate chapters with data collected using the MoQTOF.

Neisseria meningitidis is an obligate human pathogen causing over 1000 cases of meningococcal disease within the U.K., 10 % of which result in long-term disability or fatality. 10-70 % of the population carry N. meningitidis in their nasopharynx, the natural reservoir of this bacterium, as a commensal. The host-pathogen interactions of this species are complex and a greater understanding of the molecular mechanisms involved in pathogenesis and immune evasion is required. Three aspects of N. meningitidis pathogenesis were explored in this study. One mechanism of immune evasion which promotes serum resistance of N. meningitidis is recuitment of complement factor H through domains 6 and 7 (fH₆₇) by factor H binding protein (fHbp). In this study, mouse fH₆₇ was recombinantly expressed and purified. fHbp did not bind mouse fH₆₇ at physiologically relevant protein concentrations. The structure of mouse fH₆₇ was solved, showing differences in domain orientation and surface chemistry compared to the human version of this protein, potentially accounting for the host specificity of this interaction. Type IV pili (T4P) are crucial adhesins of N. meningitidis, the fibre of which is composed of thousands of copies of PilE. A method was developed to recombinantly produce large quantities of this protein from a variety of meningococcal strains and the structure was solved of one PilE protein. Subsequent analysis was performed with the PilE proteins investigating their interaction with the putative pilus receptor CD46 and human epithelia as well as their immunogenicity. A method was also established to produce PilC, the proposed tip-assocoated adhesin of T4P. ZapE has recently been identified as an important protein in pathogen colonisation, functioning as an ATPase linked to Z-ring formation in bacterial cell fission. Both N. meningitidis and E. coli ZapE were recombinantly produced. The domain boundaries were mapped and ATPase activity was confirmed. No interaction was seen with FtsZ but DNA binding and modulation was observed by shift assays, the exact function of which remains to be elucidated in future studies.

<p>Age-related macular degeneration is one of the leading causes of vision loss in the world. While identification of various environmental risk factors including but not limited to smoking, ethnicity, and diet have been reported to contribute to the complex etiology of AMD, age and genetics remain the largest susceptibility factors in its pathogenesis. Initially, with the identification of the common Y402H variant in CFH, approximately 35% of the genetic determinants of AMD had been identified with the majority remaining unknown. Therefore, we set forth to A) identify additional AMD susceptibility genes that contribute to AMD through the use to next generation sequencing technologies and B) to assess associated alleles for pathogenicity in the attempt to interpret their functional contributions to AMD outcome as observed via patient serum and zebrafish analysis. In doing such, we have identified both common and rare variants that contribute to the heritability of AMD. Additionally, we report one of the first instances of a rare variant significantly increasing disease onset and a gene with increased rare mutational burden in AMD patients. All together adding to our understanding of the genetics of AMD and potentially leading to putative therapeutic targets.</p> / Dissertation

Borrelia hermsii, the primary etiological agent of tick-borne relapsing fever in North America, binds the complement regulatory protein factor H (FH) as a means of evading opsonophagocytosis and the alternative pathway of complement. The sequence of the gene encoding the FH-binding protein has been determined. The protein is unique to B. hermsii and has been designated FhbA. Analyses of B. hermsii isolates revealed that FhbA is expressed by 24 of the 25 isolates tested. fhbA was demonstrated to be a single genetic locus through pulsed-field gel electrophoresis, restriction digest, and hybridization analyses, and all isolates possessing fhbA carry it on a 200 kb linear plasmid, whereas isolates that lack fhbA instead carry a 170 kb linear plasmid.To investigate the molecular basis of the interaction between FhbA and FH, truncated FhbA proteins were generated and tested for FH binding. Binding required both N- and C-terminal domains indicating conformational determinants are needed for FH binding. Further mutagenesis established that two C-terminal coiled-coil domains and a loop are involved in the interaction with FH. Potential variation in FhbA among isolates was analyzed by DNA sequence analysis. Two FhbA types, FhbAl and FhbA2, were delineated. Both FhbA types share a conserved C terminus containing the coiled-coil structures involved in binding FH. Additionally, it was demonstrated through whole-cell adsorption and ALBI assays that B. hermsii also binds FHL-1. To assess the specificity of the immune response to FhbA, recombinant FhbAl and FhbA2 were screened with serum from infected mice and humans. FhbA was found to be expressed and antigenic during infection. To localize the epitopes of FhbAl and FhbA2, truncations were screened with infection serum. The epitopes were determined to be conformational. Lastly, type-specific PCR primers were generated to implement rapid differentiation of strains bearing fhbA1 versus fhbA2.Together, these analyses indicate that FH/FHL-1 binding is a prevalent virulence mechanism allowing complement evasion by B. hermsii and provide insight into the antigenic structure of FhbA. Additionally, the data can be applied to the future development of species-specific diagnostic tools and will advance the studies on the epidemiology of relapsing fever in North America.

O paciente, um menino brasileiro de família japonesa e pais consagüíneos, é portador de deficiência concomitante de C9 (C9D) e Fator (F) H. Detectamos níveis reduzidos de FH (16,8µg/mL), C3 e FB no seu soro. O Western Blot confirmou a ausência da proteína de 150 kDa (FH). Sua mãe também apresentou níveis reduzidos de FH (140,5µg/mL), C3 e FB, enquanto o pai e a irmã apresentaram níveis reduzidos de FH. C9 também estava reduzido no soro do paciente (5,6µg/mL). O seqüenciamento do cDNA de FH do paciente revelou a presença de uma substituição homozigota G453A, codificando uma His127Arg. Esta substituição é também homozigota na mãe e provavelmente altera a estrutura terciária do FH e/ou seu perfil de secreção, uma vez que o FH é produzido pelos fibroblastos do paciente. O seqüenciamento de fragmentos do DNA genômico de C9 do paciente revelou a ausência da mutação Arg95, principal causa de C9D entre japoneses. O paciente é portador de uma mutação missense que possivelmente impede a secreção de FH, contudo, não pudemos identificar mutações envolvidas na C9D do paciente. / Our proband, Brazilian from a family of Japanese descent and history of consanguinity, carries C9 (C9D) and FH deficiencies. He was referred with severe recurrent pneumonia. FH (16,8 µg/mL), C3 and FB were present in the patient at low levels. Western blot assays confirmed the complete absence of 150 kDa (FH). His mother also had FH (140,5 µg/mL), C3 and FB low levels, while his father and sister presented only FH low levels. C9 was present in low levels (5,6 µg/mL) and only a very faint ~70 kDa band (expected size) was detected. Sequencing of proband?s FH cDNA revealed a homozygous G453A substitution, encoding a His127Arg. This substitution is also homozygous in the mother and may alter FH protein tertiary structure and/or its secretion profile, as we detected FH production in patient?s fibroblast. Sequencing of proband?s C9 genomic DNA fragments revealed the absence of Arg95 mutation, main cause of C9D in other C9D Japanese patients. The proband carries a missense mutation that may impair the FH secretion, but we couldn?t identify mutations explaining its C9D.

Nosso grupo estudou paciente com antecedente de infecções graves e deficiência homozigota Fator H (mutação CG453T&rarr;CA453T). Esta mutação leva a troca de códon Arg127His na molécula de Fator H (FH) resultando em acúmulo deste no retículo endoplasmático. Quando tratada a cultura de fibroblastos do paciente com curcumina in vitro, estes apresentaram aumento de secreção do FH, que mesmo mutado, apresentava função reguladora preservada. Neste protocolo, foi utilizado Theracurmin® (curcumina nanopartículada) para tratar a deficiência de FH deste paciente. Em avaliação prévia ao tratamento, foi diagnosticado lúpus com grau de atividade SLEDAI 4/105. No tratamento experimental, foram avaliados nível plasmático de curcumina e tetrahidrocurcumina. O paciente não apresentou sintomas adversos. Foi possível identificar que os níveis de curcumina e seus metabólitos se relacionaram a discreto aumento de FH detectado por Western Blot, porém sem normalização do FH e C3. O grau de atividade do lúpus se manteve estável ao longo de todo o tratamento. / Our group investigated a patient with a past of severe infections and homozygous deficiency Factor H (mutation CG453T &rarr; CA453T). This mutation leads to Arg127His codon exchange in the Factor H (FH) molecule resulting in accumulation of this protein in the endoplasmic reticulum. Once the culture of fibroblasts of the patient was treated with curcumin in vitro, they presented increased secretion of FH, which had his regulatory function. In this protocol, Theracurmin® (nanoparticle curcumin) was used to treat the FH deficiency of this patient. In pre-treatment evaluation, the pacient was diagnosed lupus with SLEDAI grade of activity 4/105. In the experimental treatment, plasma levels of curcumin and tetrahydrocurcumin were evaluated. The patient hasn\'t had adverse symptoms. It was possible to identify that the levels of curcumin and its metabolites were related to the discrete increase of FH detected by Western Blot, but without normalization of FH and C3. The degree of lupus activity remained stable throughout the treatment.

A properdina tem a capacidade de estabilizar o complexo enzimático C3bBb, com função de C3-convertase da Via Alternativa, capaz de clivar moléculas de C3, gerando C3a e C3b. Diferentes trabalhos têm sugerido que a properdina pode se ligar diretamente à superficie de um patógeno independentemente complexo enzimático C3bBb. No que diz respeito à interação de properdina com Leptospira tanto patogênica quanto não patogênica, nada se conhece na literatura. Neste trabalho demostramos que tanto a properdina presente no SHN, quanto purificada e todos os seus oligômeros interagiram com tais espiroquetas. Também observamos que a ligação da properdina pode acontecer diretamente na superfície da bactéria ou após ligação prévia do fragmento C3b. Observamos também, que na presença de SHN estas bactérias foram totalmente eliminadas, no entanto, 70% das bactérias sobreviveram quando incubadas com SHD-P. Já a adição de properdina purificada ao SHD-P provoca uma marcante diminuição no número de leptospiras viáveis. Avaliamos também quais proteínas bacterianas teriam a capacidade de se ligar à properdina. Entre as proteínas recombinantes de L. interrogans, apenas a lipoproteína LIC11087, uma proteína presente unicamente na superfície de leptospiras patogênicas, interagiu com a properdina. Todos os oligômeros de properdina presentes no SHN interagiram com a lipoproteína LIC11087. Determinamos por quantificação do complexo enzimático usando anti-Factor B policlonal que a properdina apresenta uma significativa atividade reguladora quando se depositava na superfície das bactérias não patogênicas, promovendo desta maneira, a formação da C3-convertase da Via Alternativa. Constatamos também nos sorovares patogênicos, pouca atividade reguladora pela properdina quando estas leptospiras foram pré-incubadas com a proteína. Também encontramos que a ligação da properdina na superfície de leptospiras contribui para um aumento da fagocitose por polimorfonucleares humanos de leptospiras, principalmente das não patogênicas. Nossos dados obtidos até o momento sugerem que a properdina liga-se na superfície das leptospiras patogênicas e não patogênicas; participa no processo de eliminação de leptospiras não patogênicas pela Via Alternativa; e, após sua deposição na superfície das bactérias, contribui para a formação de uma C3-convertase nas bactérias não patogênicas, diferente ao modelo tradicional. / Properdin is a positive regulatory protein that stabilizes the C3- and C5-convertases of the alternative pathway. Several studies have suggested that properdin can bind directly to the surface of a pathogen regardless enzyme complex C3bBb. With regard to the interaction of properdin with both pathogenic Leptospira and non-pathogenic, nothing is known in the literature. In this work we demonstrate that both properdin present in SHN and purified and all their oligomers interacted with spirochetes and of properdin can binding directly on the surface of bacteria or after prior binding of C3b fragment. We also observed that the Activation of the alternative pathway of complement is crucial for killing non-pathogenic L. biflexa and properdin acts effectively since this bacterium proliferates in P-depleted human serum. Since the addition of purified properdin the SHD-P causes a marked decrease in the number of viable leptospires. We also evaluated bacterial proteins which have the ability to bind to properdin. Among several recombinant leptospiral membrane proteins tested, lipoprotein LIC11087, present only in pathogenic Leptospira, was the ligand for P, P2, P3 and P4. Determined by quantifying the enzyme complex using polyclonal anti-factor B that properdin presents a significant regulatory activity when deposited on the surface of non-pathogenic bacteria, thereby promoting the formation of C3 convertase Alternative pathway. We found also in pathogenic serovars, little regulatory activity by properdin when they were preincubated leptospires with the protein. We also found that the binding of properdin in leptospiras surface contributes to increased phagocytosis of leptospira by human polymorphonuclear, mainly from non-pathogenic. Our data obtained suggest that properdin binds to Leptospira species and may play an important role to limit the proliferation of non-pathogenic Leptospira; participates in leptospiras elimination process nonpathogenic Via Alternative; and, after deposition on the surface of bacteria, it contributes to the formation of a C3 convertase in non-pathogenic bacteria, different from the traditional model.