Thymic alterations during Paracoccidioides brasiliensis infection
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1
State University of Campinas, Brazil
Thymus is a lymphoid organ responsible for the development and maturation of T lymphocytes. To exercise this function, the thymic microenvironment should be preserved by a fine control of chemokines and growth factors released by stromal components. Such soluble thymus components directly influence the migration of T lymphocyte precursors from perivascular space to the region cortical and subsequent migration to the medullar region. Despite its importance, the thymus has been reported as a target organ in several pathologic conditions, e.g. infections. Studies from our laboratory have shown that experimental infection with Paracoccidioides brasiliensis (Pb), the causative agent of the most prevalent systemic mycosis in South America, is able to invade the thymus and to induce thymic microenvironmental changes. Herein, thymuses from mice infected with the P. brasiliensis virulent isolate (Pb18) in its yeast phase were analyzed for thymic index, changes in thymic architecture, accumulation of adipose tissue, and expression of matrix metalloproteinases (MMPs) as well as their tissue inhibitors (TIMPs). Our results show severe thymic atrophy, which is accompanied by loss of its architecture and replacement of stromal cells by adipose tissue. Besides, an enhanced expression and widespread distribution of MMP-2, MMP-9, TIMP-1 and TIMP-2 were observed in thymus from Pb-infected animals. We assume that these thymic alterations are related to the high death of thymocytes and premature egress of immature thymocytes to the peripheral lymphoid organs. Our results reinforce the idea that thymic compartment disturbances may be involved in the immunossupressive phenomenon frequently associated to Pb infection.
Acknowledgements
Fapesp#2008/58604-0.
Keywords:
MMP-2,
MMP-9,
Thymus,
Thimic Atrophy,
Paracoccidioides brasiliensis
Conference:
15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013.
Presentation Type:
Abstract
Topic:
Immune-mediated disease pathogenesis
Citation:
Di Gangi
R,
Da Costa
TA,
Rovarotto
CF,
Thomé
R and
Vernaud
LC
(2013). Thymic alterations during Paracoccidioides brasiliensis infection.
Front. Immunol.
Conference Abstract:
15th International Congress of Immunology (ICI).
doi: 10.3389/conf.fimmu.2013.02.00080
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Received:
08 Mar 2013;
Published Online:
22 Aug 2013.
*
Correspondence:
Mrs. Liana Maria C Vernaud, State University of Campinas, Campinas, Brazil, verinaud@unicamp.br