Heat-shock protein induction in adriamycin and picornavirus-infected cardiocytes

Both chemicals, such as the chemotherapy agent adriamycin, and viruses, such as the picornaviruses coxsackievirus B3 and encephalomyocarditis virus, cause metabolic injury in myocardial cells. This injury includes depression of cellular RNA and protein synthesis and production of oxygen free radicals which are known to induce increased expression of "heat-shock" or stress proteins (hsp). These hsp can stimulate potent T lymphocyte responses that may then contribute to cardiac damage associated with adriamycin therapy and picornavirus infections.

To determine whether adriamycin and the picornaviruses stimulate hsp expression, cultured neonatal myocardial cells from BALB/c Cum mice were treated with heat-shock, adriamycin and either infectious or ultraviolet irradiated (noninfectious) CVB3. The treated myocardial cell homogenates were subjected to polyacrylamide gel electrophoresis and Western blot analysis for 70 kilodalton hsp. To determine whether these treatments stimulated T lymphocyte responses (presumably to hsp), BALB/c Cum mice were injected with 0.1 ml complete Freund's adjuvant containing 0.1 mg of heat-killed mycobacterium tuberculosis, 10 mg/kg adriamycin or 5 x 10(4) plaque-forming units CVB3 intraperitoneally. Splenic lymphocytes obtained 7 days later from these animals were evaluated in a 51Cr release cytotoxicity assay to cultured myocytes treated with heat-shock, adriamycin or virus. Cytolytic T lymphocytes (CTL) were characterized as to T cell subset and T cell receptor (TcR) utilization treating CTL populations with anti-CD4 or anti-CD8 antibodies or with anti-alpha/beta TcR or anti-gamma/delta TcR antibodies.

Both adriamycin and infectious virus treatment of myocardial cells stimulated increased hsp expression. Ultraviolet irradiation of the virus prevents virus replication and failed to elicit hsp production in heart cells. Two types of CTL were detected. Animals injected with complete Freund's adjuvant virus, and adriamycin produced CD8+, gamma/delta TcR+ CTL that were not major histocompatibility complex antigen restricted since both CBA (H-2k) and BALB/c (H-2d) myocardial cells were lysed. Virus-specific CTL, belonging to the CD4+, alpha/beta TcR+ population, were detected in CVB3-infected mice.

Different agents that metabolically injure myocardial cells can induce increased expression of one or more hsp. CTL presumably directed to these hsp can cross-reactively lyse targets treated with any of the hsp inducing agents. This observation raises the question whether multiple exposures of individuals to dramatically different hsp-inducing agents might result in increasingly damaging immune responses.