La clairance mucociliaire est un processus physico-chimique qui sert à transporter et éliminer le mucus bronchique. Pour cela, des milliards d'appendices de taille micrométrique, que l'on nomme cils, recouvrent l'épithélium respiratoire. Ces cils propulsent le mucus en suivant un motif périodique comprenant une phase de poussée où leur pointe peut pénétrer dans le mucus, et une phase de récupération où ils sont totalement immergés dans le fluide périciliaire. Un dysfonctionnement de ce processus peut engendrer de nombreux problèmes de santé. Il a été observé expérimentalement que les cils ne battent pas aléatoirement, mais synchronisent leurs battements avec leurs voisins, formant ainsi des ondes métachronales. Toutefois, les observations in vivo sont extrêmement difficiles à réaliser, et les propriétés de ces ondes restent mal connues. Dans cette thèse, nous utilisons un solveur Lattice Boltzmann - Frontière Immergée afin de reproduire un épithélium bronchique et étudier l'émergence, ainsi que les capacités de transports et de mélanges, de ces ondes / The mucociliary clearance process is a physico-chemical process which aims is to transport and eliminate bronchial mucus. To do so, billions of micro-sized appendages, called cilia, cover the respiratory epithelium. These cilia propel the mucus by performing a periodical pattern composed of a stroke phase where their tips can enter the mucus layer, and a recovery phase where the cilia are completely immersed in the periciliary liquid layer. A failure of this process may induce numerous health problems. It has been experimentally observed that cilia do not beat randomly, but instead adapt their beatings accordingly to their neighbours, forming metachronal waves. However, in vivo observations are extremely difficult to perfom, and the properties of these waves remain poorly understood. In this thesis, we use a Lattice Boltzmann - Immersed Boundary solver to reproduce a bronchial epithelium and study the emergence, as well as the transport and mixing capacities, of these waves

Dos peixes peçonhentos encontrados no Brasil os bagres destacam-se pelo número de acidentes provocados. O objetivo deste trabalho foi caracterizar os componentes tóxicos presentes na peçonha e no muco. Obtivemos uma média protéica de 3,1 mg/mL (peçonha) e 1,4 mg/mL (muco). O perfil eletroforético da peçonha e do muco possui poucas bandas protéicas. O fracionamento isolou 11 frações para peçonha e 13 frações para o muco. Com relação às atividades biológicas avaliadas, as frações peptídicas induziram danos teciduais ao passo que as frações protéicas induziram processo inflamatório. Isolamos duas frações com atividade antimicrobiana para cada secreção. Isolamos uma toxina de 65,1 kDa que apresenta homologia com Wap65 e análise por microscopia intravital revelou que esta proteína causa aumento dos leucócitos rolantes assim como a presença de leucócitos aderidos ao endotélio. Nossos resultados indicam uma diferença entre os componentes protéicos e peptídicos do muco e da peçonha. Finalmente, conseguimos isolar e caracterizar a proteína Wap65 da peçonha deste peixe. / Of the venomous fish found in Brazil, catfish noteworthy for the number of accidents they cause. The objective of this study was to characterize the toxic compounds present in the venom and mucus. We obtained an average protein intake of 3,1 mg / mL (venom) and 1,4 mg / mL (mucus). The electrophoretic profile of venom and mucus has a few protein bands. Fractionation isolated 11 fractions to the venom and 13 fractions to the mucus. With respect to biological activities evaluated, the peptide fractions induced tissue damage while the protein fractions induced inflammation. We isolated two fractions with antimicrobial activity for each sample. We isolated a toxin of 65,1 kDa which shows homology with Wap65 and intravital microscopy analysis revealed that this protein causes an increase in leukocyte rolling as well as the presence of leukocytes adhered to the endothelium. Our results indicate a difference between the peptide and protein components of mucus and venom. Finally, we isolate and characterize the protein Wap65 from the venom of this fish.

As raias são peixes peçonhentos e estão frequentemente associadas a acidentes em seres humanos, principalmente na região Norte do Brasil, favorecidos pelo hábito desses peixes de permanecerem no fundo de águas rasas e pela contínua utilização humana dos rios. Os ferrões das raias causam lesões dolorosas, edema, necrose, e o muco que recobre toda a extensão do corpo desses peixes pode aumentar a gravidade desses ferimentos. O objetivo deste trabalho foi avaliar a resposta imunológica induzida pelo muco de Paratrygon aiereba nativo ou irradiado por raios gama de 60Co em modelos animais. Foram realizados ensaios imunoenzimáticos e Western blotting para verificar a resposta humoral e reatividade cruzada dos soros provenientes de camundongos Swiss e coelhos New Zealand previamente imunizados contra o veneno, muco nativo ou irradiado. A indução da produção de anticorpos in vitro, as subclasses de IgG e a quantificação de citocinas foram analisados. Além de realizados ensaios de soroneutralização da atividade edematogênica in vitro e in vivo e de viabilidade celular. Os dados foram analisados estatisticamente por meio de análise de variância. O protocolo de imunização possibilitou a obtenção de soros com títulos satisfatórios de anticorpos policlonais. O muco e veneno de P. aiereba são imunogênicos e apresentam reatividade antigênica. O muco nativo ou irradiado induziu a produção de anticorpos IgG e esses reconheceram antígenos presentes no muco de outras espécies de raias. Células esplênicas de animais imunizados contra o muco irradiado produziram IFN-γ, TNF- α e IL-10 e também foi observada a produção sérica de TNF-α (grupo imunizado contra o muco irradiado) e de IL-6 e IL-17 (grupo imunizado contra o muco nativo). O soro anti-muco irradiado reduziu a atividade edematogênica in vitro, ao contrária da in vivo que não foi neutralizada. Os resultados corroboram o uso da radiação ionizante, com produção de anticorpos altamente responsivos e melhor resposta imune, além de comprovar que o muco de Paratrygon aiereba foi capaz de estimular resposta imune adaptativa celular e humoral. / Freshwater stingrays are venomous animals, frequently associated with accidents in northern Brazil where the shallow waters and the human use of the rivers favour close proximity between the fish and potential victims. Ray stings induce painful lesions, edema, necrosis, and the mucus that covers the body of these fishes may increase the severity of the wounds. The aim of this work was to evaluate the immune response induced by native or 60Co Paratrygon aiereba mucus in animal models. Enzyme linked immunosorbent assays and western blots were performed to compare humoral immune response as well as cross reactivity using antibodies raised in mice or rabbits against venom or mucus, the latter either in its native or irradiated form. Antibody production in vitro, immunoglobulins subclasses and cytokines production were evaluated. Immunization resulted in good levels of antibodies. Interestingly, both the mucus and the venom share many cross reactive components. Furthermore, antibodies raised against native mucus or its irradiated counterpart were cross-reactive against the mucus of other stingray species. Splenic cells from mice immunized with irradiated mucus secreted IFN-γ, TNF-α and IL-10. The serum raised against irradiated mucus reduced edematogenic activity in vitro, but not in vivo, when the venom and the serum are injected separately. Our results corroborate the potential of ionizing radiation as a detoxifying agent for immunogens, with production of high antibody titers and, that the highly abundant mucus of freshwater stingrays contains basically the same repertoire of antigens as the venom, inducing the synthesis of high levels of neutralizing antibodies.

O objetivo do presente trabalho foi propiciar o acesso in vivo ao epitélio respiratório e estudar a frequência de batimento ciliar (FBC) e a diferença de potencial transepitelial (DP) em um modelo murino de doença alérgica das vias aéreas induzida por ovoalbumina. Camundongos Swiss foram sensibilizados com ovoalbumina (OVA) através de duas injeções intraperitoneais de alérgico com o adjuvante hidróxido de alumínio (dias 0 e 14) e quatro inalações de OA 1% (dias 22, 24, 26 e 28). O grupo controle (S) foi tratado com salina 0,9 % seguindo o mesmo protocolo. Após 48h da última inalação, os camundongos foram anestesiados, a traquéia foi exposta longitudinalmente (1x4 mm) e o epitélio pode ser visualizado. A FBC foi mensurada pela técnica estroboscópica antes (basal) e logo após a administração inalatória das drogas (salbutamol e brometo de ipratrópio). A DP foi mensurada nos grupos S e OVA. Foram avaliados o lavado broncoalveolar e o remodelamento do epitélio da cavidade nasal, traquéia e vias aéreas distais. Nenhuma diferença foi encontrada na FBC basal entre os grupos (OVA e S), no entanto o grupo OVA mostrou uma DP basal significativamente menor. A inalação de salbutamol (3.5.10-3M ou 3.5.10-4M) elevou a FBC nos grupos estudados (p<0,05). O brometo de ipratrópio (10- 4M e 6.10-4M) não influenciou a FBC basal. Nossos resultados mostraram que é possível avaliar a FBC e a DP in vivo em um modelo murino de doença pulmonar alérgica crônica, e indicam que o processo inflamatório não afeta a FBC, mas contribui para o aumento de muco nas vias aéreas com conseqüências deletérias ao transporte mucociliar facilitando a retenção / The aim of the present work was to propitiate the in vivo assessment of the respiratory epithelium. The effects of salbutamol and ipratropium bromide on ciliary beat frequency (CBF) in a murine model of allergic airway disease were addressed. Transepithelial electric potential difference (PD) was also measured in order to verify the integrity of the epithelial barrier. Mice were sensitized with ovalbumin (OVA) by two intraperitoneal injections of allergen (days 0 and 14) and four inhalations of OVA 1% (days 22, 24, 26 and 28). The control group was treated with saline following the same procedures. After 48 hs of the last inhalation, mice were anesthetized, trachea was opened longitudinally (1 x 4 mm) and the ciliated epithelium could be visualized. CBF was measured by a modification on the videoscopic technique. We measured the CBF before and just after the administration of aerosolized substances. The PD was also measured on groups OVA and S. Additionally, the eosinophil cell count was measured on broncoalveolar lavage (BAL) in order to access the magnitude of airway inflammation. No difference on baseline CBF was noticed between groups (OVA and S), however the OVA group had a significantly lower PD. The administration of aerosolized capsaicin (3.10-9M) and salbutamol (3.5.10-3M or 3.5.10-4M) increased CBF in all groups studied. Ipratropium bromide (10-4M and 6.10- 4M) did not influence the CBF. The eosinophil cell count in broncoalveolar lavage was higher in OVA group compared to S group. CBF and PD results indicate that the inflammatory process does not affect the ciliary beat frequency but augments the amount of mucus in the airway, with deleterious consequences to the mucociliary transport facilitating mucus retention. Our results demonstrated for the first time the possibiliy of studying airway epithelium in an in vivo murine model of allergic airway disease

Os caracóis terrestres pertencem às famílias Achatinidae (África) e Helicidae (Europa). A espécie mais conhecida é a Achatina fulica (Gigante africano), sendo a mais recomendada para as regiões tropicais e subtropicais devido a sua capacidade de adaptação a estes climas. O muco de caracóis terrestres Achatina sp tem sido pesquisado devido sua atividade cicatrizante, além da atividade antibacteriana. A suplementação (plantas com finalidades cicatrizantes definidas como: confrei, papaína e centelha asiática nas rações destes animais) teve o propósito de caracterizar a composição glicoproteica do muco, considerando o bem-estar do animal, haja vista que os mesmos não foram sacrificados. Fez-se uso de uma metodologia envolvendo a coleta através de estímulo manual da glândula podal, responsável pela secreção do muco. Metodologia esta divergente de alguns autores que fizeram uso de estímulo elétrico com corrente elétrica nos animais para a coleta do muco, método este que vai contra os propósitos de bem-estar animal. Este estudo, além de utilizar uma metodologia menos drástica e prejudicial aos animais, permitiu que os mesmos retornassem ao seu ambiente de criação. As análises realizadas por testes colorimétricos e espectroscópicos, constataram que as alterações apresentadas nos testes foram muito semelhantes; no entanto, mostraram uma variação significativa na composição glicoproteica dos mucos analisados. / The terrestrial snails belong to the families Achatinidae (Africa) and Helicidae (Europe). The most known species is the Achatina fulica (Giant African), being the most recommended for the tropical and subtropical regions due its capacity of adaptation to these climates. Mucus of terrestrial snails Achatina sp has been searched had its wound healing activity, beyond the antibacterial activity. The suplementation (plants with defined wound healing purposes as comfrey, papain and centella asiatic in the rations of these animals) had the intention to characterize the glycoprotein composition of mucus, considering well-being of the animal, since the same ones had not been sacrificed. Using a methodology holding the collection through manual stimulation of the podal, responsible gland for the secretion of mucus. This methodology is divergent of some authors who had used electric stimulation with electric current on the animals for the collection of mucus, method contrary to the intentions of animal well-being. This study, beyond using a less drastic and harmful methodology to the animals, allowing that the same ones returned to its own creation environment. The analyses carried through for color and spectroscopy tests, evidenced that the alterations presented in the tests had been very similar; however, showed a significant variation in the glycoproteic composition of the analysed mucus.

O tabagismo está fortemente associado ao desenvolvimento da Doença Pulmonar Obstrutiva Crônica, porém poucos estudos que relatam alterações funcionais ou inflamatórias nas vias aéreas superiores em jovens são encontrados na literatura. Nosso objetivo foi investigar as alterações funcionais e inflamatórias nas vias aéreas superiores e inferiores em jovens tabagistas com idade igual ou inferior a 35 anos. Setenta e dois indivíduos participaram do estudo: 32 jovens não tabagistas (JNT) saudáveis (21±4 anos, 29 homens) e 40 jovens tabagistas subdivididos de acordo com a carga tabágica: menor que 2,5 anos-maço (< 2,5) (19±2 anos, 20 homens) e igual ou maior que 2,5 anos-maço (>= 2,5) (24 ± 5 anos, 17 homens e três mulheres). Foram avaliados os dados demográficos, os dados clínicos, os sintomas de desconforto das vias aéreas por meio do questionário SNOT-20, os volumes e capacidades pulmonares por meio do teste de função pulmonar, o transporte mucociliar nasal por meio do teste de tempo de trânsito da sacarina, a propriedade de superfície do muco nasal por meio do ângulo de contato, a inflamação na cavidade nasal por meio da contagem total e diferencial das células e citocinas em lavado nasal e a inflamação de vias aéreas inferiores por meio do pH do condensado do ar exalado. Observamos neste estudo que os jovens tabagistas >= 2,5 foram mais velhos comparados aos JNT e com os tabagistas < 2,5 (p < 0,01). Comparados com os JNT, os tabagistas >= 2,5 apresentaram maior índice de massa corporal (p=0,036), de frequência cardíaca (p=0,001) e de pressão arterial sistólica (p=0,036). Os tabagistas >= 2,5 apresentaram maior queixa sobre tosse (p=0,05) e secreção nasal escorrendo para a garganta (p=0,016) quando comparados com os JNT e tabagistas < 2,5. Não encontramos diferenças significativas na pontuação total do questionário SNOT-20 (p=0,140), nos valores do teste de função pulmonar e nos valores do ângulo de contato (p=0,803) entre os grupos. O tempo de trânsito da sacarina foi significativamente menor nos jovens tabagistas (5,9 ± 3,1 minutos) quando comparados aos JNT (7,7 ± 4,1 minutos, p=0,033). Na análise do lavado nasal encontramos maior número de células totais em tabagistas < 2,5 (48+-14) e tabagistas >= 2,5 (37+-25) comparados aos JNT (24+-12, p < 0,001). Encontramos também maior número de macrófagos (p=0,001), células ciliadas (p=0,008) e células caliciformes (p=0,004) nos tabagistas < 2,5 e tabagistas >= 2,5 quando comparados aos JNT, e maiores concentrações de mieloperoxidase nos tabagistas < 2,5 comparados aos tabagistas >= 2,5 (p=0,005). Os valores do pH do EBC foram menores em tabagistas >= 2,5 (7,65 ± 0,42) comparados com os tabagistas < 2,5 (7,83 ± 0,26) e com os JNT (7,90 ± 0,21, p=0,038). Por meio de análise de regressão linear, verificamos um efeito dose-dependente significativo do tabagismo sobre a redução dos valores do pH do EBC (r=-0,47, p < 0,001). Concluímos que o tabagismo em jovens tabagistas com idade igual ou inferior a 35 anos induz alterações do transporte mucociliar nasal, inflamação nasal e inflamação em vias aéreas inferiores e que essas alterações estão associadas à carga tabágica / Cigarette smoking is strongly associated with the development of Chronic Obstructive Pulmonary Disease, but few studies that reported functional or inflammatory changes in upper airway in young are found in the literature. We aimed to evaluate the effects of smoking on nasal mucociliary clearance, the mucus surface property and if there is inflammation in the nasal cavity and lower airways in young smokers aged less than 35 years. Of the 200 individuals contacted by telephone, 72 individuals entered in the study: 32 healthy young nonsmokers (YNS) (21 ± 4 years, 29 male) and 40 young smokers, subdivided according to smoking history: less than 2.5 pack-years (< 2.5) (19 ± 2 years, 20 male) and 2.5 pack-years or more ( >= 2.5) (24 ± 5 years, 17 male and three female). We assessed demographic data, clinical data, SNOT-20 questionnaire for symptoms of airway discomfort, the volumes and lung capacities by the pulmonary function test, the nasal mucociliary clearance using the saccharine transit test, the mucus surface property by the contact angle, the inflammation in the nasal cavity by the total and differential count of cells and cytokines in nasal lavage and inflammation of the lower airways by the exhaled breath condensate pH. In this study, we observed that young smokers >= 2.5 were older compared to YNS and smokers < 2.5 (p < 0.01). Compared with YNS, smokers >= 2.5 had higher body mass index (p=0.036), heart rate (p=0.001) and systolic blood pressure (p=.036). Smokers >= 2.5 complained more about cough (p = 0.05) and post-nasal discharge (p=0.016) when compared to YNS and smokers < 2.5. No significant differences were found in the total score of the SNOT-20 (p=0.140), in the pulmonary function test and mucus contact angle (p=0.803) between groups. The saccharine transit time was significantly lower in young smokers (5.9 ± 3.1 minutes) compared to YNS (7.7 ± 4.1 minutes, p=0.033). The number of total cells in nasal lavage fluid were greater in smokers < 2.5 (48±14) and smokers >= 2.5 (37 ± 25) compared to YNS (24 ± 12, p < 0.001). We also found greater number of macrophages (p=0.001), ciliated cells (p=0.008) and goblet cells (p = 0.004) in smokers < 2.5 and smokers >= 2.5 compared to YNS and a higher concentration of myeloperoxidase in smokers < 2.5 compared to smokers >= 2.5 (p=0.005). The EBC pH were lower in smokers >= 2.5 (7.65 ± 0.42) compared with smokers < 2.5 (7.83 ± 0.26) and with YNS (7.90 ± 0.21, p=0.038). Linear regression analysis confirmed a significant dose-dependent effect of smoking in decreasing EBC pH (r= -0.47, p < 0.001). We conclude that cigarette smoking induces changes in nasal mucociliary clearance, nasal inflammation and inflammation in the lower airways in young smokers aged less than 35 years and these changes are associated with smoking history

O tabagismo está fortemente associado ao desenvolvimento da Doença Pulmonar Obstrutiva Crônica, porém poucos estudos que relatam alterações funcionais ou inflamatórias nas vias aéreas superiores em jovens são encontrados na literatura. Nosso objetivo foi investigar as alterações funcionais e inflamatórias nas vias aéreas superiores e inferiores em jovens tabagistas com idade igual ou inferior a 35 anos. Setenta e dois indivíduos participaram do estudo: 32 jovens não tabagistas (JNT) saudáveis (21±4 anos, 29 homens) e 40 jovens tabagistas subdivididos de acordo com a carga tabágica: menor que 2,5 anos-maço (< 2,5) (19±2 anos, 20 homens) e igual ou maior que 2,5 anos-maço (>= 2,5) (24 ± 5 anos, 17 homens e três mulheres). Foram avaliados os dados demográficos, os dados clínicos, os sintomas de desconforto das vias aéreas por meio do questionário SNOT-20, os volumes e capacidades pulmonares por meio do teste de função pulmonar, o transporte mucociliar nasal por meio do teste de tempo de trânsito da sacarina, a propriedade de superfície do muco nasal por meio do ângulo de contato, a inflamação na cavidade nasal por meio da contagem total e diferencial das células e citocinas em lavado nasal e a inflamação de vias aéreas inferiores por meio do pH do condensado do ar exalado. Observamos neste estudo que os jovens tabagistas >= 2,5 foram mais velhos comparados aos JNT e com os tabagistas < 2,5 (p < 0,01). Comparados com os JNT, os tabagistas >= 2,5 apresentaram maior índice de massa corporal (p=0,036), de frequência cardíaca (p=0,001) e de pressão arterial sistólica (p=0,036). Os tabagistas >= 2,5 apresentaram maior queixa sobre tosse (p=0,05) e secreção nasal escorrendo para a garganta (p=0,016) quando comparados com os JNT e tabagistas < 2,5. Não encontramos diferenças significativas na pontuação total do questionário SNOT-20 (p=0,140), nos valores do teste de função pulmonar e nos valores do ângulo de contato (p=0,803) entre os grupos. O tempo de trânsito da sacarina foi significativamente menor nos jovens tabagistas (5,9 ± 3,1 minutos) quando comparados aos JNT (7,7 ± 4,1 minutos, p=0,033). Na análise do lavado nasal encontramos maior número de células totais em tabagistas < 2,5 (48+-14) e tabagistas >= 2,5 (37+-25) comparados aos JNT (24+-12, p < 0,001). Encontramos também maior número de macrófagos (p=0,001), células ciliadas (p=0,008) e células caliciformes (p=0,004) nos tabagistas < 2,5 e tabagistas >= 2,5 quando comparados aos JNT, e maiores concentrações de mieloperoxidase nos tabagistas < 2,5 comparados aos tabagistas >= 2,5 (p=0,005). Os valores do pH do EBC foram menores em tabagistas >= 2,5 (7,65 ± 0,42) comparados com os tabagistas < 2,5 (7,83 ± 0,26) e com os JNT (7,90 ± 0,21, p=0,038). Por meio de análise de regressão linear, verificamos um efeito dose-dependente significativo do tabagismo sobre a redução dos valores do pH do EBC (r=-0,47, p < 0,001). Concluímos que o tabagismo em jovens tabagistas com idade igual ou inferior a 35 anos induz alterações do transporte mucociliar nasal, inflamação nasal e inflamação em vias aéreas inferiores e que essas alterações estão associadas à carga tabágica / Cigarette smoking is strongly associated with the development of Chronic Obstructive Pulmonary Disease, but few studies that reported functional or inflammatory changes in upper airway in young are found in the literature. We aimed to evaluate the effects of smoking on nasal mucociliary clearance, the mucus surface property and if there is inflammation in the nasal cavity and lower airways in young smokers aged less than 35 years. Of the 200 individuals contacted by telephone, 72 individuals entered in the study: 32 healthy young nonsmokers (YNS) (21 ± 4 years, 29 male) and 40 young smokers, subdivided according to smoking history: less than 2.5 pack-years (< 2.5) (19 ± 2 years, 20 male) and 2.5 pack-years or more ( >= 2.5) (24 ± 5 years, 17 male and three female). We assessed demographic data, clinical data, SNOT-20 questionnaire for symptoms of airway discomfort, the volumes and lung capacities by the pulmonary function test, the nasal mucociliary clearance using the saccharine transit test, the mucus surface property by the contact angle, the inflammation in the nasal cavity by the total and differential count of cells and cytokines in nasal lavage and inflammation of the lower airways by the exhaled breath condensate pH. In this study, we observed that young smokers >= 2.5 were older compared to YNS and smokers < 2.5 (p < 0.01). Compared with YNS, smokers >= 2.5 had higher body mass index (p=0.036), heart rate (p=0.001) and systolic blood pressure (p=.036). Smokers >= 2.5 complained more about cough (p = 0.05) and post-nasal discharge (p=0.016) when compared to YNS and smokers < 2.5. No significant differences were found in the total score of the SNOT-20 (p=0.140), in the pulmonary function test and mucus contact angle (p=0.803) between groups. The saccharine transit time was significantly lower in young smokers (5.9 ± 3.1 minutes) compared to YNS (7.7 ± 4.1 minutes, p=0.033). The number of total cells in nasal lavage fluid were greater in smokers < 2.5 (48±14) and smokers >= 2.5 (37 ± 25) compared to YNS (24 ± 12, p < 0.001). We also found greater number of macrophages (p=0.001), ciliated cells (p=0.008) and goblet cells (p = 0.004) in smokers < 2.5 and smokers >= 2.5 compared to YNS and a higher concentration of myeloperoxidase in smokers < 2.5 compared to smokers >= 2.5 (p=0.005). The EBC pH were lower in smokers >= 2.5 (7.65 ± 0.42) compared with smokers < 2.5 (7.83 ± 0.26) and with YNS (7.90 ± 0.21, p=0.038). Linear regression analysis confirmed a significant dose-dependent effect of smoking in decreasing EBC pH (r= -0.47, p < 0.001). We conclude that cigarette smoking induces changes in nasal mucociliary clearance, nasal inflammation and inflammation in the lower airways in young smokers aged less than 35 years and these changes are associated with smoking history

The intestinal mucosa is made up of complex secreted mucus layer consist of mainly mucin 2 (MUC2) and antimicrobial components that defend the underlining cellular barrier from intrusion by luminal microbiota and toxins. In inflammatory bowel diseases (IBD), the mucosal integrity is compromised. This can result from a combination of altered host genetics, gut immune responses and environment factors. However, it is the presence of intestinal bacteria that is central to the pathogenesis of IBD. As part of the dynamic gut microbial flora, mucolytic bacteria produce a wide range of glycosidases that are able to remove the outer oligosaccharide chains of MUC2, which allow other luminal bacteria to further degrade the mucin. We hypothesised that increased mucolytic bacteria will cause excessive degradation of the mucus layer, which in turn, allow more luminal bacteria to be in close proximity to the underlining epithelial cells resulting in inflammation. Consistent with our group’s previous semi-quantitative bacterial 16S rRNA gene clone library analysis, we found increased Ruminococcus gnavus in non-inflamed ulcerative colitis (UC) mucosa. R. gnavus was previously isolated by others based on its mucolytic property. In this study, we quantify total mucosa-associated bacteria and mucolytic bacteria, namely, R. gnavus, R. torques, Akkermansia muciniphila and bifidobacteria. We were able to show quantitatively that total mucosa-associated bacteria were increased in IBD. There was also a population shift in the mucosa-associated mucolytic bacteria, which were increased overall. There was significantly more R. gnavus in non-inflamed IBD biopsies. For the first time, we were also able to demonstrate that R. gnavus can degrade human MUC2 in vitro. To examine whether the numerical association of R. gnavus in IBD does have functional influence on intestinal inflammation and Paneth cell antimicrobial peptide gene expression, we fed mice with R. gnavus. Interestingly, R. gnavus feeding did not result in histological or molecular evidence of gut inflammation; however, it was able to specifically induce Paneth cell cryptdins and lysozyme P genes expression in 3 week old, antibiotic pre-treated C57BL/6 mice. This demonstrated that R. gnavus is not a pathogenic bacterium, which will directly cause colitis. However, the increased Paneth cell response suggested the need for host innate defence when R. gnavus is increased. Other than bacterial degradation, altered host genetics will also influence the mucus barrier. There is evidence to suggest that the MUC2 gene is highly unstable and is susceptible to gene copy number variation (CNV). Therefore, we hypothesised that MUC2 CNV is present, which may result in altered oligomerisation of the MUC2 glycoprotein causing endoplasmic reticulum stress of the goblet cells that appears to be characteristic of UC. Currently, our data partly support the presence of MUC2 CNV. However, further investigation is required to verify the MUC2 CNV identity. Only then can a high throughput methodology be designed to screen a large population for any association with IBD.

<p>The gastric mucosa is frequently exposed to endogenously secreted hydrochloric acid of high acidity. Gastric mucosal defense mechanisms are arranged at different levels of the gastric mucosa and must work in unison to maintain its integrity. </p><p>In this thesis, several mechanisms underlying gastric mucosal resistance to strong acid were investigated in anesthetized rats and mice. The main findings were as follows:</p><p>Only when acid secretion occurred did the pH gradient in the mucus gel withstand back-diffusion of luminal acid (100 mM or 155 mM HCl), and keep the juxtamucosal pH (pH_jm) neutral. Thus, when no acid secretion occurred and the luminal pH was 0.8-1, the pH gradient was destroyed. </p><p>Bicarbonate ions, produced concomitant with hydrogen ions in the parietal cells during acid secretion and blood-borne to the surface epithelium, were carried transepithelially through a DIDS-sensitive transport. </p><p>Prostaglandin-dependent bicarbonate secretion seemed to be less important in maintaining a neutral pH_jm. </p><p>Removal of the loosely adherent mucus layer did not influence the maintenance of the pH_jm. Hence, only the firmly adherent mucus gel layer, approximately 80µm thick, seemed to be important for the pH_jm. </p><p>Staining of the mucus gel with a pH-sensitive dye revealed that secreted acid penetrated the mucus gel from the crypt openings toward the gastric lumen only in restricted paths (channels). One crypt opening was attached to one channel, and the channel was irreversibly formed during acid secretion. </p><p>Gastric mucosal blood flow increased on application of strong luminal acid (155 mM HCl). This acid-induced hyperemia involved the inducible but not the neural isoform of nitric oxide synthase. These results suggest a novel role for iNOS in gastric mucosal protection and indicate that iNOS is constitutively expressed in the gastric mucosa. </p><p>It is concluded that a pH gradient in the gastric mucus gel can be maintained during ongoing acid secretion, since the acid penetrates the mucus only in restricted channels and bicarbonate is carried from the blood to the lumen via a DIDS-sensitive transporter.</p>

The gastric mucosa is frequently exposed to endogenously secreted hydrochloric acid of high acidity. Gastric mucosal defense mechanisms are arranged at different levels of the gastric mucosa and must work in unison to maintain its integrity. In this thesis, several mechanisms underlying gastric mucosal resistance to strong acid were investigated in anesthetized rats and mice. The main findings were as follows: Only when acid secretion occurred did the pH gradient in the mucus gel withstand back-diffusion of luminal acid (100 mM or 155 mM HCl), and keep the juxtamucosal pH (pHjm) neutral. Thus, when no acid secretion occurred and the luminal pH was 0.8-1, the pH gradient was destroyed. Bicarbonate ions, produced concomitant with hydrogen ions in the parietal cells during acid secretion and blood-borne to the surface epithelium, were carried transepithelially through a DIDS-sensitive transport. Prostaglandin-dependent bicarbonate secretion seemed to be less important in maintaining a neutral pHjm. Removal of the loosely adherent mucus layer did not influence the maintenance of the pHjm. Hence, only the firmly adherent mucus gel layer, approximately 80µm thick, seemed to be important for the pHjm. Staining of the mucus gel with a pH-sensitive dye revealed that secreted acid penetrated the mucus gel from the crypt openings toward the gastric lumen only in restricted paths (channels). One crypt opening was attached to one channel, and the channel was irreversibly formed during acid secretion. Gastric mucosal blood flow increased on application of strong luminal acid (155 mM HCl). This acid-induced hyperemia involved the inducible but not the neural isoform of nitric oxide synthase. These results suggest a novel role for iNOS in gastric mucosal protection and indicate that iNOS is constitutively expressed in the gastric mucosa. It is concluded that a pH gradient in the gastric mucus gel can be maintained during ongoing acid secretion, since the acid penetrates the mucus only in restricted channels and bicarbonate is carried from the blood to the lumen via a DIDS-sensitive transporter.