The role of alveolar type II cells in swine leptospirosis

Abstract

RESUMO.-[O papel das células alveolares tipo II na leptospirose suína.] Setenta e três suínos adultos de criação extensiva, abatidos em Teresina, no estado do Piauí e Timon, no estado do Maranhão, constituíram o grupo de estudo. O diagnóstico da leptospirose foi realizado utilizando a técnica de soroaglutinação microscópica (MAT), auxiliada por imunoistoquímica e reação em cadeia pela polimerase. A SAM registrou a ocorrência de anticorpos anti-leptospiras em 10,96% (8/73) dos suínos. A imunoistoquímica permitiu a visualização de antígenos de Leptospira spp. em pulmões de 87,67% (64/73) dos suínos. Havia hiperplasia do tecido linfoide associado ao brônquio e alterações circulatórias como, congestão do septo alveolar, hemorragia parenquimatosa e edema no interior de alvéolos. Os focos de inflamações pulmonares eram mais numerosos (p=0,0312) nos animais infectados, bem como o espessamento do septo alveolar (p=0,0006). A quantificação de células alveolares tipo II marcadas pelo anticorpo anti-TTF-1 (Thyroid This study aimed to investigate a possible relationship between alveolar type II cells and the inflammatory response to infection with Leptospira spp., and thus comprise a further element that can be involved in the pathogenesis of lung injury in naturally infected pigs. The study group consisted of 73 adult pigs that were extensively reared and slaughtered in Teresina, Piauí state, and Timon, Maranhão state, Brazil. The diagnosis of leptospirosis was made using the microscopic agglutination test (MAT) aided by immunohistochemistry and polymerase chain reaction. The MAT registered the occurrence of anti-Leptospira antibodies in 10.96% (8/73) of the pigs. Immunohistochemistry allowed for the visualization of the Leptospira spp. antigen in the lungs of 87.67% (64/73) of the pigs. There was hyperplasia of bronchus-associated lymphoid tissue and circulatory changes, such as congestion of alveolar septa, parenchymal hemorrhage and edema within the alveoli. Lung inflammation was more intense (p = 0.0312) in infected animals, which also showed increased thickening of the alveolar septa (p = 0.0006). Evaluation of alveolar type II (ATII) cells using an anti-TTF-1 (Thyroid Transcription Factor-1) antibody showed that there were more immunostained cells in the non-infected pigs (53.8%) than in the infected animals (46.2%) and that there was an inverse correlation between TTF-1 positive cells and the inflammatory infiltrate. There was no amplification of Leptospira DNA in the lung samples, but leptospiral DNA amplification was observed in the kidneys. The results of this study showed that a relationship exists between a decrease in alveolar type II cells and a leptospire infection. Thus, this work points to the importance of studying the ATII cells as a potential marker of the level of lung innate immune response during leptospirosis in pigs. Transcription Factor-1) mostrou que existia mais células imunocoradas em suínos não infectados (53,8%) comparados aos infectados (46,2%) e uma correlação inversa em relação ao infiltr...