Cathepsin S is a cysteine protease in the papain family that digests antigens as part of the adaptive immune response, activates receptors, and is associated with extracellular matrix degradation in autoimmune diseases and cancer. A comprehensive review of the literature revealed potential pH- and redox-dependent specificity switches in the proteolytic specificity of cathepsin S. These were investigated through the digestion of peptides across a variety of pH and redox conditions. These experiments confirmed both pH- and redox-dependent patterns of proteolytic specificity, with narrowed specificity in alkaline and oxidizing conditions. An analysis of publicly available structures of cathepsin S identified a lysine residue which descends into the S3 pocket of the active site above pH 7.0, acting as a pH-dependent gate. Energy minimization of crystal structures show disorder in the loops which make up the active site of the protein, which increases in disorder when the disulfide bonds on the surface of cathepsin S are reduced. This is explored as a potential mechanism for the redox-dependent specificity identified in the digest experiments. These specificity switches may contribute to pathological structural damage attributed to cathepsin S, as pH and redox dysregulation are features of several cathepsin S-associated diseases. / Doctor of Philosophy / Proteases are protein enzymes that break the bonds of other proteins, cleaving them into pieces. Cathepsin S is a protease that has many important roles in the body. If you have ever become immune to something, it is thanks to cathepsin S. Proteases can't cleave every protein: they are limited to specific sequences, and this is called proteolytic specificity. It is usually determined by the shape and charge of the active site of the enzyme. The purpose of this set of experiments was to find out whether two environmental factors change the specificity of cathepsin S: pH (the balance of proton donors and acceptors), and redox state (the balance of electron donors and acceptors). By combining cathepsin S with short proteins of varying sequences in different pH and redox conditions, we found that both of these conditions impact which sequences cathepsin S can cleave most easily. We identified areas of the structure of cathepsin S that are likely responsible for these specificity switches. The pH-dependence can be explained by an amino acid that bends down into the active site of cathepsin S at high pH, closing off part of the pocket and limiting what protein sequences can fit into it. The redox-dependence may be explained by bonds on the surface of cathepsin S being broken in some environments, making the active site more flexible and able to accept more protein sequences. These specificity switches may explain the destructive behavior of cathepsin S in a variety of diseases, since in many of these diseases, pH and redox states get out of balance.

No abstract available. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1996.

Cathepsin S is a protease important in major histocompatibility complex (MHC) class II antigen presentation and also in degrading the extracellular matrix. Studies, most of them experimental, have shown that cathepsin S is involved in different pathological conditions such as obesity, inflammation, atherosclerosis, diabetes, and cancer.    The overall hypothesis of this report is that high levels of circulating cathepsin S, is a biomarker that reflects pathology induced by inflammation and obesity. The overall aim of this report was to investigate possible associations between circulating cathepsin S, inflammation, glucometabolic disturbance, and its associated diseases in the community. As cathepsin S appears to be a novel risk marker for several pathological conditions, we also wanted to examine the effect of dietary intervention on circulating cathepsin S concentrations.    This thesis is based on data from three community-based cohorts, the Uppsala longitudinal study of adult men (ULSAM), the prospective investigation of the vasculature in Uppsala seniors (PIVUS), and a post-hoc study from the randomized controlled NORDIET trial.    In the first study, we identified a cross-sectional positive association between serum cathepsin S and two markers of cytokine-mediated inflammation, CRP and IL-6. These associations were similar in non-obese individuals. In longitudinal analyses, higher cathepsin S at baseline was associated with higher CRP and IL-6 levels after six years of follow-up. In the second study, we identified a cross-sectional association between increased serum levels of cathepsin S and reduced insulin sensitivity. These associations were similar in non-obese individuals. No significant association was observed between cathepsin S and insulin secretion. In longitudinal analysis, higher cathepsin S levels were associated with an increased risk of developing diabetes during the six-year follow-up. In the third study, we found that higher serum levels of cathepsin S were associated with increased mortality risk. Moreover, in the ULSAM cohort, serum cathepsin S was independently associated with cause-specific mortality from cardiovascular disease and cancer. In the fourth study, we identified that adherence to an ad libitum healthy Nordic diet for 6 weeks slightly decreased the levels of plasma cathepsin S in normal or marginally overweight individuals, relative to the control group. Changes in circulating cathepsin S concentrations were correlated with changes in body weight, LDL-C, and total cholesterol.    Conclusion: This thesis shows that circulating cathepsin S is a biomarker that independently reflects inflammation, insulin resistance, the risk of developing diabetes, and mortality risk. Furthermore, a Nordic diet moderately reduced cathepsin S levels in normal-weight and overweight men and women. This effect may be partially mediated by diet-induced weight loss and possibly by reduced LDL-C concentrations.

Cathepsin S is a protease important in major histocompatibility complex (MHC) class II antigen presentation and also in degrading the extracellular matrix. Studies, most of them experimental, have shown that cathepsin S is involved in different pathological conditions such as obesity, inflammation, atherosclerosis, diabetes, and cancer. The overall hypothesis of this report is that high levels of circulating cathepsin S, is a biomarker that reflects pathology induced by inflammation and obesity. The overall aim of this report was to investigate possible associations between circulating cathepsin S, inflammation, glucometabolic disturbance, and its associated diseases in the community. As cathepsin S appears to be a novel risk marker for several pathological conditions, we also wanted to examine the effect of dietary intervention on circulating cathepsin S concentrations. This thesis is based on data from three community-based cohorts, the Uppsala longitudinal study of adult men (ULSAM), the prospective investigation of the vasculature in Uppsala seniors (PIVUS), and a post-hoc study from the randomized controlled NORDIET trial. In the first study, we identified a cross-sectional positive association between serum cathepsin S and two markers of cytokine-mediated inflammation, CRP and IL-6. These associations were similar in non-obese individuals. In longitudinal analyses, higher cathepsin S at baseline was associated with higher CRP and IL-6 levels after six years of follow-up. In the second study, we identified a cross-sectional association between increased serum levels of cathepsin S and reduced insulin sensitivity. These associations were similar in non-obese individuals. No significant association was observed between cathepsin S and insulin secretion. In longitudinal analysis, higher cathepsin S levels were associated with an increased risk of developing diabetes during the six-year follow-up. In the third study, we found that higher serum levels of cathepsin S were associated with increased mortality risk. Moreover, in the ULSAM cohort, serum cathepsin S was independently associated with cause-specific mortality from cardiovascular disease and cancer. In the fourth study, we identified that adherence to an ad libitum healthy Nordic diet for 6 weeks slightly decreased the levels of plasma cathepsin S in normal or marginally overweight individuals, relative to the control group. Changes in circulating cathepsin S concentrations were correlated with changes in body weight, LDL-C, and total cholesterol. Conclusion: This thesis shows that circulating cathepsin S is a biomarker that independently reflects inflammation, insulin resistance, the risk of developing diabetes, and mortality risk. Furthermore, a Nordic diet moderately reduced cathepsin S levels in normal-weight and overweight men and women. This effect may be partially mediated by diet-induced weight loss and possibly by reduced LDL-C concentrations.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-06-27T19:16:23Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) José Luiz de Figueiredo_TESE DE DOUTORADO_SA.pdf: 20285168 bytes, checksum: 2ae5d11950e2cb6dc18e886511b1c189 (MD5) / Made available in DSpace on 2016-06-27T19:16:23Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) José Luiz de Figueiredo_TESE DE DOUTORADO_SA.pdf: 20285168 bytes, checksum: 2ae5d11950e2cb6dc18e886511b1c189 (MD5) Previous issue date: 2015-08-24 / Doença renal crônica acelera o desenvolvimento de ateroscleroses. A catepsina S é uma potente protease que quebra as fibras de elastina na parede das artérias e gera peptídeos bioativos de elastina, promovendo inflamação e calcificação vascular. Objetivo: Verificar os efeitos da inibição seletiva da catepsina S nas ateroscleroses de camundongos deficientes em apolipoproteína E (ApoE-/-) com doença renal crônica. Método: A doença renal crônica foi induzida por nefrectomia subtotal (5/6) em camundongos ApoE-/-, alimentados com uma dieta com alto teor de gorduras e colesterol. Os camundongos hipercolesterolêmicos, com doença renal crônica receberam essa dieta misturada com 6,6 ou 60 mg / kg do inibidor seletivo da catepsina S - RO5444101 ou a mesma dieta sem o inibidor seletivo da catepsina S (controle). Resultados: Camundongos com doença renal crônica tinham níveis plasmáticos significativamente mais elevados de osteopontina, osteocalcina e osteoprotegerina (204%, 148%, e 55%, respectivamente; p<0,05), que foram inibidos pelo RO5444101 (60%, 40%, e 36%, respectivamente; P<0,05). Imagens moleculares fluorescentes revelaram uma redução significativa na atividade da catepsina em camundongos tratados. O RO5444101 diminuiu também a atividade osteogênica. Avaliação histológica na placa aterosclerótica demonstrou que o RO5444101 reduziu a imunorreatividade da catepsina S (P<0,05), a degradação da elastina (P=0.01), o tamanho da placa (P=0.01), a acumulação de macrófagos (P<0,01), o fator de diferenciação do crescimento-15 (P=0.0001), a calcificação (atividade da fosfatase alcalina), P<0,01; e a osteocalcina, P<0,05). Além disso, o inibidor da catepsina S ou o siRNA significativamente diminuiu a expressão do fator de diferenciação do crescimento-15 e a proteína quimiotáctica de monócitos-1 numa linha de células de macrófagos de camundongos e macrófagos primários humanos. Conclusão: A inibição seletiva da catepsina S atenua a progressão de lesões ateroscleróticas em camundongos deficientes em apolipoproteína E com doença renal crônica. / Chronic kidney disease accelerates the development of atherosclerosis. Cathepsin S is a potent protease that cleaves elastin in the arteries wall and generates bioactive elastin peptides, promoting vascular inflammation and calcification. Objective: To verify the effects of selective inhibition of cathepsin S in atherosclerosis in apolipoprotein E deficient (ApoE-/-) mice with chronic kidney disease. Methods: chronic kidney disease was induced by a subtotal (5/6) nephrectomy in a high-fat high-cholesterol fed ApoE-/- mice. Hypercholesterolemic mice with CRD received a diet admixed with 6.6 or 60 mg/kg of the selective cathepsin S inhibitor RO5444101 or a diet without the selective inibidor of the catepsina S (control). Results: chronic kidney disease mice had significantly higher plasma levels of osteopontin, osteocalcin, and osteoprotegerin (204%, 148%, and 55%, respectively; P<0.05), which were inhibited by RO5444101 (60%, 40%, and 36%, respectively; P<0.05). Near-infrared fluorescence molecular imaging revealed a significant reduction in cathepsin activity in treated mice. RO5444101 decreased osteogenic activity. Histologic assessment in atherosclerotic plaque demonstrated that RO5444101 reduced immunoreactive cathepsin S (P<0.05), elastin degradation (P<0.01), plaque size (P<0.01), macrophage accumulation (P<0.01), growth differentiation factor-15 (P<0.0001), and calcification, alkaline phosphatase activity, (P<0.01); osteocalcin, (P<0.05). Furthermore, cathepsin S inhibitor or siRNA significantly decreased expression of growth differentiation factor-15 and monocyte chemotactic protein-1 in a murine macrophage cell line and human primary macrophages. Conclusion: The selective inhibition of cathepsin S attenuates the progression of atherosclerotic lesions in apolipoprotein E deficient mice with chronic kidney disease