Lack of cathepsin activities alter or prevent the development of lung granulomas in a mouse model of sarcoidosisReport as inadecuate

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Respiratory Research

, 12:13

First Online: 01 December 2011Received: 09 September 2010Accepted: 20 January 2011


BackgroundRemodeling of lung tissues during the process of granuloma formation requires significant restructuring of the extra-cellular matrix and cathepsins K, L and S are among the strongest extra-cellular matrix degrading enzymes. Cathepsin K is highly expressed in various pathological granulomatous infiltrates and all three enzymes in their active form are detected in bronchoalveolar lavage fluids from patients with sarcoidosis. Granulomatous inflammation is driven by T-cell response and cathepsins S and L are actively involved in the regulation of antigen presentation and T-cell selection. Here, we show that the disruption of the activities of cathepsins K, L, or S affects the development of lung granulomas in a mouse model of sarcoidosis.

MethodsApolipoprotein E-deficient mice lacking cathepsin K or L were fed Paigen diet for 16 weeks and lungs were analyzed and compared with their cathepsin-expressing littermates. The role of cathepsin S in the development of granulomas was evaluated using mice treated for 8 weeks with a potent and selective cathepsin S inhibitor.

ResultsWhen compared to wild-type litters, more cathepsin K-deficient mice had lung granulomas, but individually affected mice developed smaller granulomas that were present in lower numbers. The absence of cathepsin K increased the number of multinucleated giant cells and the collagen content in granulomas. Cathepsin L deficiency resulted in decreased size and number of lung granulomas. Apoe- mice treated with a selective cathepsin S inhibitor did not develop lung granulomas and only individual epithelioid cells were observed.

ConclusionsCathepsin K deficiency affected mostly the occurrence and composition of lung granulomas, whereas cathepsin L deficiency significantly reduced their number and cathepsin S inhibition prevented the formation of granulomas.

Electronic supplementary materialThe online version of this article doi:10.1186-1465-9921-12-13 contains supplementary material, which is available to authorized users.

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Author: Andriy O Samokhin - Jacques Yves Gauthier - M David Percival - Dieter Brömme


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