Trypanosoma cruzi infection induces up-regulation of cardiac muscarinic acetylcholine receptors in vivo and in vitro

• Published in: Brazilian journal of medical and biological research Vol. 41; no. 9; pp. 796 - 803
• Main Authors: Peraza-Cruces, K, Gutiérrez-Guédez, L, Castañeda Perozo, D, Lankford, C R, Rodríguez-Bonfante, C, Bonfante-Cabarcas, R
• Format: Journal Article
• Language: English; Portuguese
• Published: Brazil Associação Brasileira de Divulgação Científica 01.09.2008
• Subjects: Animals; BIOLOGY; Chagas disease; Chagas Disease - blood; Chagas Disease - metabolism; Chronic Disease; Enzyme-Linked Immunosorbent Assay; Immunogenic theory; Interferon-alpha - blood; Interleukin-1beta - blood; Interleukin-6 - blood; Leukocytes, Mononuclear - chemistry; Male; MEDICINE, RESEARCH & EXPERIMENTAL; Muscarinic acetylcholine receptor; Myocytes, Cardiac - chemistry; Neurogenic theory; Rats; Rats, Sprague-Dawley; Receptors, Muscarinic - analysis; Receptors, Muscarinic - metabolism; Super-sensitivity; Trypanosoma cruzi; Up-Regulation; Chagas disease; Neurogenic theory; Super-sensitivity; Muscarinic acetylcholine receptor; Trypanosoma cruzi; Immunogenic theory
• ISSN: 0100-879X; 1414-431X; 1414-431X; 0100-879X
• DOI: 10.1590/S0100-879X2008000900009

The pathogenesis of chagasic cardiomyopathy is not completely understood, but it has been correlated with parasympathetic denervation (neurogenic theory) and inflammatory activity (immunogenic theory) that could affect heart muscarinic acetylcholine receptor (mAChR) expression. In order to further understand whether neurogenic and/or immunogenic alterations are related to changes in mAChR expression, we studied two models of Trypanosoma cruzi infection: 1) in 3-week-old male Sprague Dawley rats chronically infected with T. cruzi and 2) isolated primary cardiomyocytes co-cultured with T. cruzi and peripheral blood mononuclear cells (PBMC). Using [3H]-quinuclidinylbenzilate ([3H]-QNB) binding assays, we evaluated mAChR expression in homogenates from selected cardiac regions, PBMC, and cultured cardiomyocytes. We also determined in vitro protein expression and pro-inflammatory cytokine expression in serum and cell culture medium by ELISA. Our results showed that: 1) mAChR were significantly (P < 0.05) up-regulated in right ventricular myocardium (means +/- SEM; control: 58.69 +/- 5.54, N = 29; Chagas: 72.29 +/- 5.79 fmol/mg, N = 34) and PBMC (control: 12.88 +/- 2.45, N = 18; Chagas: 20.22 +/- 1.82 fmol/mg, N = 19), as well as in cardiomyocyte transmembranes cultured with either PBMC/T. cruzi co-cultures (control: 24.33 +/- 3.83; Chagas: 43.62 +/- 5.08 fmol/mg, N = 7 for both) or their conditioned medium (control: 37.84 +/- 3.84, N = 4; Chagas: 54.38 +/- 6.28 fmol/mg, N = 20); 2) [(3)H]-leucine uptake was increased in cardiomyocytes co-cultured with PBMC/T. cruzi-conditioned medium (Chagas: 21,030 +/- 2321; control 10,940 +/- 2385 dpm, N = 7 for both; P < 0.05); 3) plasma IL-6 was increased in chagasic rats, IL-1beta, was increased in both plasma of chagasic rats and in the culture medium, and TNF-alpha level was decreased in the culture medium. In conclusion, our results suggest that cytokines are involved in the up-regulation of mAChR in chronic Chagas disease.