Intense inflammatory lesions and early development of interstitial
fibrosis of the myocardium and skeletal muscle with spontaneous regression,
have been described in
Calomys callosus
infected with
Trypanosoma cruzi
. The genetic types of collagen present in this model were investigated
through immunohistochemistry using specific antibodies, combined with histopathology
and Picro-Sirius staining of collagen.
Thirty-five calomys were infected with the Colombian strain of
T. cruzi
and sacrificed at 24, 30, 40, 60 and 90 days post-infection. Inflammatory
lesions and fibrogenesis were prominent at the early phase of infection
and significantly decreased during late infection. Immunoisotyping of the
matrix components was performed by indirect immunofluorescence on 5 µm
thick cryostat sections using specific antibodies against laminin, fibronectin
and isotypes I, III and IV of collagen. In the early phase, positive deposits
of all the matrix components were present, with predominance of fibronectin,
laminin and collagens types I and III in the myocardium and of types III
and IV in the skeletal muscles. From the 40th day, type IV collagen predominates
in the heart. At the late phase of infection (60th to 90th day), a clear
fragmentation and decrease of all the matrix components were detected. Findings
of the present study indicate that a modulation of the inflammatory process
occurs in the model of
C. callosus
, leading to spontaneous regression of fibrosis independent of the genetic
types of collagen involved in this process.
