Indiana University-Purdue University Indianapolis (IUPUI) / Rationale: CD55 down-regulation on airway epithelium correlates with local complement activation observed in hypoxia-associated pulmonary diseases. Therefore, we hypothesized that induction of hypoxia inducible factor 1 alpha (HIF-1α) in hypoxic airway epithelium, mediates CD55 down-regulation. Methods: Chetomin and HIF-1α siRNA inhibited HIF-1α in hypoxic SAECs (1% O2), and mice lungs (10% O2). DMOG mediated HIF-1α stabilization in normoxic SAECs and mice lungs (21% O2). Transduction of SAECs with AdCA5 also stabilized HIF-1α. CD55 and CA9 transcripts were measured by RT-PCR. CD55 and HIF-1α protein expression was assessed by western blots. In vivo, immunohistochemistry (IHC) confirmed CD55 and HIF-1α expression. C3a and C5a levels in bronchoalveolar lavage fluid (BALF) were measured by ELISA. Results: HIF-1α was induced in 6 hour hypoxic SAECs (p<0.05), but CD55 transcripts were repressed (p&lt;0.05). CD55 protein was down-regulated by 72 hours (p<0.05). CA9 transcripts were elevated by 48 -72 hours (p<0.05 and p<0.01, respectively). In vivo, CD55 transcripts and protein were down- regulated by 24 hours post-hypoxia (p<0.01) which corresponded to complement activation (p<0.05) in BALF. However, CA9 was increased (p<0.01). Chetomin (100nM) treatment in 6 hour hypoxic SAECs, recovered CD55 transcripts (p<0.01) and protein (p<0.05), but down-regulated CA9 (p<0.05). Similarly, in vivo chetomin (1mg/ml) treatment recovered CD55 protein (p<0.01) and down-regulated CA9 (p<0.01). Silencing HIF-1α (50nM) in hypoxic SAECs restored CD55 transcripts by 6 hours (p<0.05), and protein expression by 24 hours (p<0.05). However, CA9 was repressed (p<0.01). In vivo silencing of HIF-1α (50µg) restored CD55 protein expression (p<0.05) but down-regulated CA9 (p<0.05). Stabilizing HIF-1α in normoxic SAECs via DMOG (1µM), down-regulated CD55 transcripts and protein (p<0.01), but increased CA9 within 6-24 hours (p<0.05 and p<0.01, respectively). HIF-1α induction by DMOG (1mg/ml) in normoxic mice lungs down-regulated CD55 transcripts (p<0.01) and protein (p<0.01), but increased CA9 (p<0.05). Induction of HIF-1α in AdCA5 (50 PFUs/cell) transduced normoxic SAECs, resulted in CD55 protein down-regulation (p<0.05), but increased CA9 (p<0.001). Conclusions: HIF-1α down-regulates CD55 on airway epithelium. Targeting this mechanism may be a potential therapeutic intervention for attenuating complement activation in hypoxic pulmonary diseases.

OBJETIVOS: Correlacionar o nível de expressão das proteínas reguladoras do complemento (Cregs) CD55, CD59, CD35 e CD46 nos linfócitos B em uma coorte de pacientes com artrite reumatoide (AR) iniciando terapia com rituximabe (RTX) com a depleção e tempo de repopulação destas células no sangue periférico, associando, ainda, o nível de expressão destas proteínas à resposta clínica conforme os critérios do Colégio Americano de Reumatologia (ACR). MÉTODOS: Dez pacientes com AR receberam duas infusões de RTX 1g separadas por intervalo de 14 dias. Análises imunofenotípicas para detecção de CD19, CD55, CD59, CD35 e CD46 foram realizadas pré-infusão e após 1, 2, 6, 12, 18 e 24 meses ou até recaída clínica. Depleção de linfócitos B no sangue periférico foi definida como valor de CD19 menor que 0,005x109/l no total de leucócitos. Resposta ACR20 em 6 meses foi considerada positiva e recaída clínica foi definida como perda dessa resposta. A não obtenção de ACR20 em 6 meses foi considerada falha de resposta ao tratamento. RESULTADOS: Dez mulheres com mediana de 49 anos e DAS28 basal de 5,6; nove delas soropositivas para fator reumatoide foram acompanhadas. Repopulação de linfócitos B ocorreu em 2 meses em cinco pacientes e em 6 meses nas demais. Houve correlação entre o nível de expressão basal de CD46 com o tempo de repopulação (coeficiente de correlação de -0,733, p=0,016). Tendência semelhante foi detectada com CD35, porém sem significância estatística (coeficiente de correlação de -0,522, p=0,12). Não houve associação entre resposta clínica e expressão das proteínas regulatórias do complemento. CONCLUSÕES: Expressão aumentada de CD46 foi preditora de repopulação mais precoce de linfócitos B em pacientes com AR tratados com RTX. Estudos com amostras maiores serão necessários para avaliar associação das demais Cregs. / OBJECTIVES: To correlate the level of expression of the complement regulatory proteins (Cregs) CD55, CD59, CD35, and CD46 on B cells from a cohort of 10 patients with rheumatoid arthritis (RA) initiating treatment with rituximab (RTX) with the depletion and time of repopulation of these cells in peripheral blood, additionally correlating the level of expression of these proteins to clinical response according to the criteria of the American College of Rheumatology (ACR). METHODS: Ten patients with RA received two 1g RTX infusions within 14 day intervals. Immunophenotype analyses for CD19, CD55, CD59, CD35 and CD46 were performed before the infusion and at 1, 2, 6, 12, 18 and 24 months or until recurrence. Depletion of B cells on peripheral blood was defined as the CD19 count < 0.005x109/l. ACR20 at 6 months was considered a good clinical response and recurrence was defined as loss of this response. RESULTS: Ten women with median age of 49 years and basal DAS28 of 5.6 were monitored; 9 were seropositive for rheumatoid factor. Repopulation of B cells occurred within 2 months in 5 patients and within 6 months in the remaining women. There was correlation between the basal level of CD46 expression and the time to achieve repopulation (correlation coefficient -0.733, p=0.016). A similar trend was observed with the CD35, but without statistical significance (correlation coefficient - 0.522, p=012). There was no association between clinical response and the complement regulatory proteins. CONCLUSIONS: Increased CD46 expression predicted earlier repopulation of B cells in RA patients treated with RTX. Studies with larger samples are necessary to assess the association with the other Cregs.

OBJETIVOS: Correlacionar o nível de expressão das proteínas reguladoras do complemento (Cregs) CD55, CD59, CD35 e CD46 nos linfócitos B em uma coorte de pacientes com artrite reumatoide (AR) iniciando terapia com rituximabe (RTX) com a depleção e tempo de repopulação destas células no sangue periférico, associando, ainda, o nível de expressão destas proteínas à resposta clínica conforme os critérios do Colégio Americano de Reumatologia (ACR). MÉTODOS: Dez pacientes com AR receberam duas infusões de RTX 1g separadas por intervalo de 14 dias. Análises imunofenotípicas para detecção de CD19, CD55, CD59, CD35 e CD46 foram realizadas pré-infusão e após 1, 2, 6, 12, 18 e 24 meses ou até recaída clínica. Depleção de linfócitos B no sangue periférico foi definida como valor de CD19 menor que 0,005x109/l no total de leucócitos. Resposta ACR20 em 6 meses foi considerada positiva e recaída clínica foi definida como perda dessa resposta. A não obtenção de ACR20 em 6 meses foi considerada falha de resposta ao tratamento. RESULTADOS: Dez mulheres com mediana de 49 anos e DAS28 basal de 5,6; nove delas soropositivas para fator reumatoide foram acompanhadas. Repopulação de linfócitos B ocorreu em 2 meses em cinco pacientes e em 6 meses nas demais. Houve correlação entre o nível de expressão basal de CD46 com o tempo de repopulação (coeficiente de correlação de -0,733, p=0,016). Tendência semelhante foi detectada com CD35, porém sem significância estatística (coeficiente de correlação de -0,522, p=0,12). Não houve associação entre resposta clínica e expressão das proteínas regulatórias do complemento. CONCLUSÕES: Expressão aumentada de CD46 foi preditora de repopulação mais precoce de linfócitos B em pacientes com AR tratados com RTX. Estudos com amostras maiores serão necessários para avaliar associação das demais Cregs. / OBJECTIVES: To correlate the level of expression of the complement regulatory proteins (Cregs) CD55, CD59, CD35, and CD46 on B cells from a cohort of 10 patients with rheumatoid arthritis (RA) initiating treatment with rituximab (RTX) with the depletion and time of repopulation of these cells in peripheral blood, additionally correlating the level of expression of these proteins to clinical response according to the criteria of the American College of Rheumatology (ACR). METHODS: Ten patients with RA received two 1g RTX infusions within 14 day intervals. Immunophenotype analyses for CD19, CD55, CD59, CD35 and CD46 were performed before the infusion and at 1, 2, 6, 12, 18 and 24 months or until recurrence. Depletion of B cells on peripheral blood was defined as the CD19 count < 0.005x109/l. ACR20 at 6 months was considered a good clinical response and recurrence was defined as loss of this response. RESULTS: Ten women with median age of 49 years and basal DAS28 of 5.6 were monitored; 9 were seropositive for rheumatoid factor. Repopulation of B cells occurred within 2 months in 5 patients and within 6 months in the remaining women. There was correlation between the basal level of CD46 expression and the time to achieve repopulation (correlation coefficient -0.733, p=0.016). A similar trend was observed with the CD35, but without statistical significance (correlation coefficient - 0.522, p=012). There was no association between clinical response and the complement regulatory proteins. CONCLUSIONS: Increased CD46 expression predicted earlier repopulation of B cells in RA patients treated with RTX. Studies with larger samples are necessary to assess the association with the other Cregs.

OBJETIVOS: Correlacionar o nível de expressão das proteínas reguladoras do complemento (Cregs) CD55, CD59, CD35 e CD46 nos linfócitos B em uma coorte de pacientes com artrite reumatoide (AR) iniciando terapia com rituximabe (RTX) com a depleção e tempo de repopulação destas células no sangue periférico, associando, ainda, o nível de expressão destas proteínas à resposta clínica conforme os critérios do Colégio Americano de Reumatologia (ACR). MÉTODOS: Dez pacientes com AR receberam duas infusões de RTX 1g separadas por intervalo de 14 dias. Análises imunofenotípicas para detecção de CD19, CD55, CD59, CD35 e CD46 foram realizadas pré-infusão e após 1, 2, 6, 12, 18 e 24 meses ou até recaída clínica. Depleção de linfócitos B no sangue periférico foi definida como valor de CD19 menor que 0,005x109/l no total de leucócitos. Resposta ACR20 em 6 meses foi considerada positiva e recaída clínica foi definida como perda dessa resposta. A não obtenção de ACR20 em 6 meses foi considerada falha de resposta ao tratamento. RESULTADOS: Dez mulheres com mediana de 49 anos e DAS28 basal de 5,6; nove delas soropositivas para fator reumatoide foram acompanhadas. Repopulação de linfócitos B ocorreu em 2 meses em cinco pacientes e em 6 meses nas demais. Houve correlação entre o nível de expressão basal de CD46 com o tempo de repopulação (coeficiente de correlação de -0,733, p=0,016). Tendência semelhante foi detectada com CD35, porém sem significância estatística (coeficiente de correlação de -0,522, p=0,12). Não houve associação entre resposta clínica e expressão das proteínas regulatórias do complemento. CONCLUSÕES: Expressão aumentada de CD46 foi preditora de repopulação mais precoce de linfócitos B em pacientes com AR tratados com RTX. Estudos com amostras maiores serão necessários para avaliar associação das demais Cregs. / OBJECTIVES: To correlate the level of expression of the complement regulatory proteins (Cregs) CD55, CD59, CD35, and CD46 on B cells from a cohort of 10 patients with rheumatoid arthritis (RA) initiating treatment with rituximab (RTX) with the depletion and time of repopulation of these cells in peripheral blood, additionally correlating the level of expression of these proteins to clinical response according to the criteria of the American College of Rheumatology (ACR). METHODS: Ten patients with RA received two 1g RTX infusions within 14 day intervals. Immunophenotype analyses for CD19, CD55, CD59, CD35 and CD46 were performed before the infusion and at 1, 2, 6, 12, 18 and 24 months or until recurrence. Depletion of B cells on peripheral blood was defined as the CD19 count < 0.005x109/l. ACR20 at 6 months was considered a good clinical response and recurrence was defined as loss of this response. RESULTS: Ten women with median age of 49 years and basal DAS28 of 5.6 were monitored; 9 were seropositive for rheumatoid factor. Repopulation of B cells occurred within 2 months in 5 patients and within 6 months in the remaining women. There was correlation between the basal level of CD46 expression and the time to achieve repopulation (correlation coefficient -0.733, p=0.016). A similar trend was observed with the CD35, but without statistical significance (correlation coefficient - 0.522, p=012). There was no association between clinical response and the complement regulatory proteins. CONCLUSIONS: Increased CD46 expression predicted earlier repopulation of B cells in RA patients treated with RTX. Studies with larger samples are necessary to assess the association with the other Cregs.