[Establishment of human cardiac C protein induced experimental autoimmune myocarditis model in rat]

To construct the recombinant plasmid of human cardiac C protein (CCP) peptide with immunogenicity and to express, purification and renature fusion protein. The fusion protein was injected to Lewis rats to establish experimental autoimmune myocarditis (EAM) model.

Total RNA was extracted from human heart and used as the template for reverse transcriptase-directed cDNA synthesis. The cDNA was then amplified by polymerase chain reaction (PCR) using oligonucleotide primers specific for CCP peptide with immunogenicity. Subsequently, the purified CCP peptide gene was cloned into PEASY-T1 vector and the ligated product was identified by PCR and DNA sequence analysis. Then the CCP target gene of positive clone was inserted into the pQE30, a prokaryotic expression vector, and the inserting plasmid was transformed into Escherichia coli. host M15. The positive clone extracted from the bacterium liquid was sieved by insertional inactivation sieve method and identified by PCR of bacterium liquid, CCP immunological peptide was purified and renatured in semipermeable membrane. EAM model in Lewis rats was induced by injection of mixture of 100 µg CCP fusion protein immunological peptide and 2.5 g/L completed Freund adjuvant from two double foot pad and subsequent abdominal injection of 0.5 µg pertussis toxin. Two, four, six, and eight weeks after immunization, hemodynamic evaluation was made and hearts underwent histological examination.

The DNA sequence analysis for cloning vector extraction revealed that the CCP target gene was cloned into pQE30 exactly. The DNA of 1000 bp length was obtained by PCR examination of bacterium liquid with transformation of express recombinants which were consistent with the expected size. Purified fusion protein in vertical slab gel electrophoresis showed 35 000 as expected. The recombinant CCP fusion protein existed in inclusion bodies of E. coli and amounted to 80% - 90% of the total protein. Hemodynamic and histological evaluations showed typical acute inflammatory responses at 2 weeks, subacute inflammatory and fibrosis changes at 4 weeks after injection, and signs of chronic dilated cardiomyopathy at 6 weeks post injection.

Combination of gene clone technique and histidine tag protein purification technique can be used to synthesize human cardiac C protein to induce EAM model in Lewis rat.