O sistema complemento participa da patogenia da Doença Hepática Alcoólica (DHA), onde C3 contribui para o acúmulo de triglicerídeos (tg) e C5 para injúria e inflamação hepática. Investigamos o papel de C5 em modelo de DHA aplicando as linhagens B6 e A/J, e geramos a linhagem congênica B6.A-Hc0 (B6 C5def). B6 e A/J foram tratados com dieta contendo ou não etanol, ou maltodextrina, por 6, 8 e 10 semanas. Em ambas as linhagens a dieta com etanol induziu hepatomegalia, acúmulo de tg e redução de IL6 e IL12 hepáticos ao longo das semanas. Os A/J tratados com etanol exibiram aumento de leucócitos circulantes, IL10 e NO hepáticos e menor acúmulo de tg hepáticos em relação aos B6. Os B6 tratados com etanol exibiram redução de IL1b, IL10 e NO hepáticos. Tratando a linhagem congênica por 10 semanas com a dieta com etanol observamos aumento de IL17 e IL10 e redução de IL1b e TGFb hepáticos nos B6.A-Hc0 em relação aos B6. Independentemente da dieta, houve aumento sérico de AST, FA, albumina, colesterol, tg e redução hepática de IL6, IL12 e IFNg nos B6.A-Hc0. Portanto, C5 promoveu um ambiente hepático pró-inflamatório e pareceu influenciar os valores séricos das enzimas de função e síntese hepática, citocinas e do perfil lipídico no modelo de DHA. / The complement system may be involved in the pathogenesis of Alcoholic Fatty Liver Disease (ALD). Murine models of ALD showed that C3 contributes to the accumulation of triglycerides (tg) in liver and the C5 seems to be involved with hepatic inflammation. We here investigated the contribution of C5 in ALD using C57Bl/6 (B6) and A/J (C5 deficient), and B6 C5 deficient congenic mice (B6.A-Hc0). B6 and A/J were treated with modified diet containing ethanol or maltodextrin for 6-10 weeks. In both strains, the ethanol diet induced hepatomegaly, increased liver tg and decreased IL6 and IL12 levels. However, total blood leukocytes counting, IL10 and NO liver production increased only in A/J. In addition, only in B6 the IL1b levels increased while IL10 and NO decreased in liver. A/J mice suffered more inflammatory damage and accumulated less liver tg than B6. In B6.A-Hc0 IL17 and IL10 increased while of IL1b and TGFb decreased when compared to B6. Independently of the diet, levels of AST, FA, albumin, cholesterol, tg increased in B6.A-Hc0 serum and IL6, IL12 and IFNg reduced in liver. In conclusion, C5 promoted a pro-inflammatory environment in the liver and influenced the serum levels of hepatic enzymes, cytokines and lipid profile.

O sistema complemento parece ter surgido com o aparecimento de C3 e fator B (FB), os únicos componentes encontrados nos organismos mais primitivos, o que sugere que a via alternativa seja a mais antiga. Fragmentos de cDNA codificantes para FB (Lox-FB) e C3 (Lox-C3) foram sintetizados a partir do RNA total isolado da glândula de veneno de Loxosceles laeta e amplificados por técnicas de RACE-PCR. Lox-FB apresenta uma organização de domínios clássica, composta por domínios CCP, vWFA e de serino protease. Os aminoácidos envolvidos na ligação ao C3b são conservados, no entanto, a tríade catalítica clássica não foi encontrada. Lox-C3 apresenta uma configuração de domínios similar a do C3 humano, contendo dois sítios putativos de processamento: um entre as cadeias α e γ, e outro entre as cadeias α e β, indicando que Lox-C3 seja composto por três cadeias. As análises filogenéticas indicaram que Lox-C3 e Lox-FB são mais próximos evolutivamente aos componentes equivalentes da aranha Hasarius adansoni, com valores de identidade de 53% e 43%, respectivamente. / The complement system seems to have arisen with the appearance of C3 and factor B (FB), the only components found in the most primitive organisms, suggesting that the alternative pathway is the oldest. cDNA fragments coding for the complement factor B (Lox-FB) and C3 (Lox-C3) were synthesized from total RNA Loxosceles laeta venom gland and amplified using RACE-PCR techniques. Lox-FB has a classical domain organization in mosaic, composed by CCPs, vWFA and serine protease domains. The amino acids involved in binding to C3b are conserved, however, the classical calatytic triad was not found. Lox-C3 presents a similar configuration of domains to C3 human and has two putative processing sites: the first one is located between α and γ chains and other between α and β chains, indicating that Lox-C3 is composed by three chains. The phylogenetic analyses indicated that Lox-C3 and Lox-FB are evolutionary closer to the equivalent components of Hasarius adansoni, with identity values of 53% and 43%, respectively.

Streptococcus pneumoniae é um importante agente causador de pneumonia, meningite e septicemia. O alto custo e a cobertura limitada da vacina conjugada atual reforçam a necessidade de se desenvolver uma vacina mais abrangente e acessível. A proteína de superfície de pneumococo A (PspA) é imunogênica e protetora em modelos animais; porém, devido à sua diversidade - há 6 clados e 3 famílias de PspA - uma vacina baseada em PspA deverá incluir fragmentos das duas famílias prevalentes (1 e 2). Neste estudo, foram produzidos fragmentos contendo a região N-terminal de PspA das famílias 1 e 2, e proteínas híbridas - contendo fusões destes fragmentos. Os anticorpos gerados contra os híbridos reconheceram PspAs nativas das duas famílias, foram capazes de se ligar a bactérias íntegras, e de aumentar a deposição de complemento em sua superfície. Finalmente, a imunização de camundongos com os híbridos foi capaz de proteger contra desafio com pneumococos contendo PspAs diversas, mostrando que estes seriam candidatos promissores na composição de uma vacina anti-pneumocócica. / Streptococcus pneumoniae is an important cause of pneumonia, meningitis and septicaemia. The high cost and limited coverage of the available conjugate vaccine reinforce the need for cost effective strategies, with broader coverage. Pneumococcal Surface Protein A (PspA) is immunogenic and protective in animal models; however, due to its diversity - there are six clades and threee families of PspA - a PspA based vaccine should include fragments of each major family (1 and 2). In the present study, we have produced fragments of the N-terminal region of PspAs families 1 and 2, and hybrid proteins - containing fusions of these fragments. Sera made against the hybrids induced antibodies that recognized PspAs from both families; these sera were also able to bind pneumococcal strains bearing diverse PspAs, and to increase complement deposition on their surface. Finally, immunization of mice with PspA hybrids was protective against challenge with pneumococci bearing diverse PspAs, showing that these hybrids should constitute promising candidates in an anti-pneumococcal vaccine.

Embora camundongos sejam resistentes à infecção por Leptospira interrogans, eles têm sido pouco utilizados para se entender os mecanismos imunes efetores contra esta bactéria. Adler & Faine mostraram em 1976 que esta resistência é dependente da resposta imune, uma vez que camundongos imunossuprimidos tornavam-se suscetíveis à L. interrogans. Outros autores mostraram que camundongos portadores de imunodeficiência grave combinada também morriam após inoculação de L. interrogans. Sabendo da importância do Sistema Complemento em infecções bacterianas, investigamos se animais C5 deficientes (C5-) são mais suscetíveis à infecção por L. interrogans que animais C5 normais (C5+). Observamos que camundongos C5- possuem menores porcentagens de linfócitos T CD8+ na circulação periférica e maiores níveis de IL-12p40 no rim e de TNF e IL-6 no pulmão que os animais C5+. Animais C57Bl/6 (B6) C5+ possuem maior porcentagem de linfócitos T CD4+ que B6 C5-, além de lesões hepáticas mais intensas, mostrando um efeito dependente de C5 e do fundo genético dos camundongos. / Although mice are resistant to Leptospira interrogans infection, they are not usual models to study the imune response against this bacteria. Adler and Faine demonstrated in 1976 the importance of the imune response, since immunosuppressed mice were suceptible to L. interrogans. Other authors showed that mice that had severe combined immunodeficiency also died when inoculated with L. interrogans. Due to the activity of the Complement System in infections, we analyzed whether C5 deficient (C5-) mice are more susceptible than C5 sufficient (C5+) mice to L. interrogans infection. C5- mice have lower percentages of T CD8+ lymphocytes in peripheral circulation and upper levels of IL-12p40 in the kidney and TNF and IL-6 in the lungs than C5+ mice. C57Bl/6 (B6) C5+ mice has higher percentages of T CD4+ lymphocytes than B6 C5- mice, in addition to stricter liver injures, exhibiting an effect dependent of C5 and of the genetic background.

A leptospirose é uma zoonose causada por leptospiras patogênicas. Para estabelecer a infecção, estas bactérias desenvolveram estratégias de escape ao sistema complemento. Neste trabalho demonstramos que o sobrenadante de cultura de leptospiras patogênicas é capaz de inibir as três vias do complemento. Observamos que esse sobrenadante possui atividade proteolítica sobre C3, C3b e iC3b, além do FB (via alternativa), C2 e C4b (via clássica e das lectinas). As proteínas C3, C4, C2 e FB também foram clivadas quando soro humano normal (SHN) foi utilizado como fonte de complemento. Demonstramos que as proteases atuam em conjunto com os reguladores do hospedeiro Fator I e Fator H na clivagem de C3b. As clivagens foram inibidas pela 1,10-fenantrolina, sugerindo a participação de metaloproteases. Metaloproteases de leptospira da família das termolisinas foram produzidas como proteínas recombinantes e clivaram C3 no SHN. Concluímos que proteases de leptospiras patogênicas podem desativar moléculas do complemento e são potencias alvos para novas terapias em leptospirose. / Leptospirosis is a zoonotic disease caused by pathogenic Leptospira. To establish the infection, these bacteria have developed strategies to escape the complement system. In this work, we demonstrate that culture supernatant from pathogenic Leptospira is capable of inhibiting the three complement pathways. We observe that this supernatant possess proteolytic activity under C3, C3b and iC3b, FB (alternative pathway), C2 and C4b (classical and lectin pathways). The proteins C3, C4, C2 and FB were also cleaved when normal human serum (NHS) was used as a source of complement. We demonstrate that these proteases act together with the host regulators Factor I and Factor H in C3b cleavage. The cleavages were inhibited by 1,10-phenanthroline, suggesting the involvement of metalloproteinases. Leptospira metalloproteinases from the thermolysin family were produced as recombinant proteins and cleaved C3 in NHS. We concluded that proteases from pathogenic Leptospira can inactivate complement molecules and are potential targets for new therapies in leptospirosis.

C3 glomerulopathy (C3G) encompasses a group of severe renal diseases characterized by “dominant C3” deposition in the renal glomerulus. Patients typically present as nephritic nephrotics, with hematuria, hypertension, heavy proteinuria and edema. Within ten years of diagnosis, 50% of affected patients progress to end-stage renal disease and require dialysis or renal transplantation. No treatment is available to halt disease progression and thus both disease recurrence and allograft loss are common after transplantation. Genetic studies of C3G have firmly implicated dysregulation of the alternative pathway (AP) of complement in disease pathogenesis. In addition to genetic factors, acquired factors like autoantibodies can also exaggerate AP activity in the circulation to cause C3G. Although AP dysregulation in the circulation (i.e. fluid-phase dysregulation) has been well studied in these patients, AP activity in the glomerular microenvironment is not well understood. In this body of work, we used MaxGel, an ex-vivo surrogate for the glomerular extracellular matrix, to study AP activity and regulation. We showed that C3 convertase can be assembled on MaxGel and elucidated the dynamics of its formation and decay in the presence of complement regulators. We confirm that on MaxGel factor H (fH) inhibits C3 convertase formation and accelerates its decay, while properdin has a stabilizing effect. We also show that the complement factor H-related proteins (FHRs) are vital to the regulation of AP activity. Consistent with our MaxGel data, CFHR gene-fusion events have been reported as genetic drivers of disease in a few familial cases of C3G. One such familial case in which we identified and characterized the rearrangement event results from a novel CFHR5-CFHR2 fusion gene. The fusion gene is translated into a circulating FHR-5/-2 protein that consists of the first two SCRs of FHR-5 followed by all four SCRs of FHR-2. The structural repetition of SCR1-2 followed by another SCR1-2 motif facilitates the formation of complex FHR-1, FHR-2 and FHR-5 multimers, which have enhanced affinity for C3b and by out-competing fH, lead to impaired C3 convertase regulation in the glomerular microenvironment. Finally, we tested gene therapy as a tool to rescue the disease phenotype and restore fluid-phase AP complement control in a mouse model of C3G (Cfh-/-/huCR1-Tg mice). Using the piggyBac transposon system, we introduced a construct derived from complement regulator 1 (CR1) into Cfh-/-/huCR1-Tg mice. Delivery of sCR1-AC via hydrodynamic tail vein injection provided constitutive circulatory expression of sCR1-AC, and in animals followed for 6 months, we found that long-term expression of this complement regulator rescued the renal phenotype. These results suggest that sCR1 may be a potential therapy for patients with this disease.

Dementia is the top global public health threat of the twenty first century. Within the dementia spectrum, Alzheimer’s disease (AD) is the most common type of dementia that occurs with aging and accounts for about 60% - 80% of diagnosed cases. But currently available discoveries failed to develop disease-modifying therapies for all patients living with AD. Recent discoveries can only partially slow down cognitive decline in a small subset of patients with limited effectiveness. The heterogeneity and complexity of the pathophysiology of AD indicate that a single drug approach may not be sufficient to prevent disease onset and progression. Human umbilical cord blood cells (HUCBC) and lithium treatment have shown promise against numerous neurological conditions, including AD. Yet, they also show significant unwanted, adverse effects. To address this barrier to yield successful treatments, we employed two key modifications to these two treatment strategy. We used human umbilical cord blood derived serum (HUCBS, also labeled as CBS) rather than HUCBC. We also utilized ionic cocrystal of lithium salicylate l-proline (LISPRO, also labeled as LP) instead of usual lithium salt. Both HUCBS and LISPRO have been shown to have strong neuroprotective, anti-inflammatory properties in separate studies conducted in transgenic AD mouse models. The studies detailed herein independently investigated the effectiveness of biological (HUCBS) and pharmacological (LISPRO) approaches in modulating the pathology and cognitive impairments in AD mouse models (e.g., 5XFAD, 3XTg-AD, APPswe/PS1dE9, and Tg2576). While administration of HUCBC stimulate anti-inflammatory pathways shown in previous studies, we found that HUCBS markedly promoted neurotrophic soluble amyloid precursor protein alpha (sAPPα) through non-amyloidogenic amyloid precursor protein (APP) processing pathway compared to adult (ABS) and aged blood serum (AgBS) in Chinese hamster ovary cells expressing wild type APP (CHO/APPwt). Using chromatographic fractionation, mass-spectrometry, and targeting complement proteins in cord blood serum fraction (αCBSF), we discovered the source of sAPPα in HUCBS as C1 complement protein. Further, intraperitoneal administration of αCBSF via osmotic minipump for 6 weeks showed prevention of cognitive impairment in 5XFAD mice assessed by novel object recognition, and Y-maze test. A series of recent studies have shown that lithium can prevent both AD- and age-associated cognitive decline. But, current United States Food and Drug Administration-approved lithium pharmaceutics (carbonate and citrate forms) have a narrow therapeutic window and unstable pharmaceutics that can cause toxicity without monitoring. Here we investigated the safety, pharmacokinetics, and therapeutic efficacy of LISPRO (LP), lithium salicylate (LS), and lithium carbonate (LC) in cell culture and mouse (B6129SF2/J, Tg2576, and 3xTg-AD) models. Cytokine profiles from the brain, plasma and splenocytes demonstrated that 8-week oral treatment with LISPRO downregulates pro-inflammatory cytokines, upregulates anti-inflammatory cytokines and suppress renal cyclooxygenase 2 (COX2) expression in Tg2576 mice. Pharmacokinetic studies indicated that LISPRO provides significantly higher brain and more steady plasma lithium levels in both B6129SF2/J and transgenic Tg2576 mice compared with lithium carbonate. Oral administration of LISPRO for 28 weeks significantly reduced β-amyloid plaques and tau phosphorylation. In addition, LISPRO significantly elevated pre-synaptic (synaptophysin) and post-synaptic protein (post synaptic density protein 95) expression in brains from transgenic 3XTg-AD mice. Moreover, female APPswe/PS1dE9 mice at 4 months of age were orally treated with LP, LS, or LC for 8- to 9- months at 2.25 mmol lithium/kg/day followed by measuring body weight, internal organs’ growth, and cognitive and non-cognitive function. LISPRO treatment prevented cognitive decline compared with transgenic APPswe/PS1dE9 cohort, as shown by shorter escape latency during training and probe trials in the Morris water maze and longer contextual freezing time during fear conditioning. As expected, LISPRO treatment also reduced depression assayed by tail suspension test and irritability assessed with the touch escape test. But, lithium treatment did not alter anxiety or locomotor activity as assessed by open field, elevated plus maze or accelerated rotarod tests. Taken together, these data indicate that both biological HUCBS and pharmacological LISPRO treatment may prove to be viable effective strategy for ameliorating Alzheimer’s like pathology and cognitive impairment in preclinical models.

Coral reefs are biologically and economically important ecosystems underpinned by corals that are able to flourish in oligotrophic waters due to their mutualistic association with dinoflagellate symbionts (genus Symbiodinium). Symbiodinium are strictly intracellular, residing within the gastrodermal tissues of the coral host, and contributing the majority of the coral’s energy requirements. Coral reefs are in rapid decline due to a range of threats such as local human influences, bleaching (loss of Symbiodnium and/or reduction of pigment), disease and ocean acidification, to which links to climate change have been made. The close association of corals and a diverse community of microbes led to development of the coral holobiont hypothesis, in which a range of microorganisms (e.g Bacteria) form a functionally-relevant mutualistic relationship with corals and Symbiodinium. This thesis aimed to fill knowledge gaps in the coral holobiont hypothesis and the host-microbe interactions within this system, including pathogen interactions and coral immune system functioning. This thesis revealed that host-microbe interactions in corals are complex, and that the underlying mechanisms of immunity and symbiosis may be similar. The findings corroborate the idea that corals maintain specific bacterial communities that have potential probiotic and nutritional value. In particular, a group of common coral associates were identified, and it is suggested that members of this group are globally occurring key associates. Corals affected by a disease previously described as “White Syndrome” were observed to undergo pronounced changes in their microbial community structure in comparison to healthy colonies. However, in contrast to previous findings, no single pathogen could be identified as the causative agent of the disease syndrome, and it is speculated that corals experiencing altered health status result in a breakdown of the resident associated microbial community structure. Culturable bacterial isolates from corals were shown to affect the growth of each other and in particular some species had great inhibitory properties. Hence, the presence of some bacterial species has the potential to influence the all over structure of the coral associated microbial community. It was also shown that changed environmental conditions may alter the growth conditions for coral associated bacteria in mucus. It is suggested that increased replication is needed in studies of bacterial assemblages on corals, as variability between coral species and sites were observed. In addition, studies of the role of coral microbial communities in health and disease should broaden their focus to more thoroughly consider the role of the coral holobiont, especially with regards to the coral host. This thesis identified the first functional Pattern Recognition Protein (PRP), a C-type lectin named Millectin, in scleractinian corals. Millectin was isolated by affinity chromatography and was shown to bind to bacterial pathogens as well as coral Symbiodinium symbionts. Gene expression of Millectin was upregulated in response to immune stimuli and the lectin was further abundantly expressed in the tissues of corals, suggesting a major role for this protein in system functioning and immunity. Further research into Millectin and a complement factor C3 homolog suggested that these molecules may have been co-opted into the equally important role of symbiont recruitment. Gene expression analysis of C3 also indicated this molecule may be involved in responses to tissue trauma. Millectin shows variability in the binding region, and hence, is the earliest evolutionary representative to date of a variable PRP. This finding, and the observed ancestral relation with vertebrate homologs, provided further information on the evolution of the innate immune system and gives further insight into invertebrate immunity.

<p>Induction of collagen-induced arthritis (CIA), an animal model for human rheumatoid arthritis, is dependent on anti-collagen type II (CII) antibodies. The effector mechanism by which autoantibodies contribute to inflammatory reactions in autoimmune diseases is not well understood. In this thesis I have studied the effector pathways used by IgG anti-CII antibodies to initiate arthritis, namely the IgG Fc receptors (FcγRs) and the complement system. We have found that FcγRIII is crucial for development of CIA, as CII-immunized mice lacking this receptor do not develop arthritis and IgG1 and IgG2b anti-CII antibodies require FcγRIII to trigger arthritis when transferred to naïve mice. The antibody-mediated arthritis was further enhanced in mice deficient in the inhibitory FcγRIIB, indicating that FcγRIIB regulates the activation of FcγRIII. Furthermore, we demonstrate that FcγRIII exist as three distinct haplotypes in mice, FcγRIII:H, FcγRIII:V and FcγRIII:T. Mice expressing the FcγRIII:H haplotype are more susceptible to CIA than mice expressing the FcγRIII:V haplotype, indicating that certain FcγRIII haplotype predisposes for CIA. We also show that the most likely FcγRIII-expressing effector cell in CIA is the macrophage, since FcγRIII-expressing macrophages exclusively can induce arthritis in FcγRIII-deficient mice challenged for CIA.</p><p>The complement system was also investigated in development of CIA. We found that this effector pathway is also necessary for onset of arthritis, as CIA was inhibited by treatment with anti-complement factor 5 (C5) antibodies. C5-deficient mice could neither develop CIA unless provided with C5-containing sera. </p><p>Taken together, the work presented in this thesis indicates that FcγRs and the complement system are crucial for the induction of experimental arthritis. These findings are important for understanding the mechanisms behind rheumatoid arthritis and blocking of these effector pathways may in the future be used as treatment of rheumatoid arthritis. </p>

<p>Haptoglobin (Hp) is a serum protein known for its ability to form a tight complex with hemoglobin (Hb) and thereby inhibiting the oxidative activity of Hb. </p><p>Mammalian Hp is synthesized as a precursor (proHp) that undergoes proteolytic cleavage by a previously unidentified enzyme in the endoplasmic reticulum (ER). In this study, a proHp-cleaving enzyme was isolated from human serum and identified as complement C1r-like protein (C1rLP). Co-expression of C1rLP with proHp in mammalian cells resulted in cleavage of the latter protein in the ER. Mutation of either the active site serine residue in C1rLP or the arginine residue in the cleavage site of Hp abolished the cleavage of proHp by C1rLP. RNAi studies in mammalian cells identified the proHp-cleaving enzyme as C1rLP.</p><p>Hp has been found in all mammals studied to date but its presence in non-mammalian species has not been unambiguously shown. By searching currently available genomic DNA and cDNA sequence databases, a gene orthologous to mammalian <i>Hp</i> was found in bony fish. Hp-like protein expressed from this gene was demonstrated to be a major Hb protein in fish serum. Surprisingly, no Hp-like gene was found in the genomes of either frog or chicken. In chicken, a protein previously described as Hp was identified as PIT54, a member of a scavenger receptor cysteine-rich family of proteins. Interestingly, ostrich serum seemed to contain two Hb-binding proteins; one similar to PIT54 and one to mammalian Hp. We are not aware of any other case where the function of one gene has been taken over by another, completely unrelated gene</p><p>Fish Hp (fHp) is composed of a serine proteinase-related domain preceded by an extension consisting of several aminoa acids and a signal peptide. The extension contains a consensus motif for cleavage by subtilisin-like proprotein convertases (SPCs). fHp was found to be cleaved by SPCs in the Golgi complex.</p><p>Collectively, this thesis presents evidence that Hp has undergone significant changes during evolution with respect to its molecular organization and to the mechanism of its proteolytic cleavage.</p>