1Universitätsklinikum Würzburg Deutsches Zentrum für Herzinsuffizienz Würzburg, Deutschland; 2Universitätsklinikum Würzburg Medizinische Klinik und Poliklinik I Würzburg, Deutschland
Aim: Previous studies have reported the presence of heart-reactive antibodies in patients with myocardial infarction (MI) and heart failure (HF). Nevertheless, the relevant antibodies produced in response to MI have not yet been fully identified. Likewise, the dynamics of post-MI B cell activation hav not yet been established in patients. In the present study we sought to longitudinally characterize the dynamic changes in the circulating memory B-cell and plamablast compartments, and the plasma reactivity profile in the prospective cohort of MI patients (ANTIK-MI study)
Methods: For this purpose, serial peripheralblood samples from 10 MI patients were collected index event (baseline), day 5, month 4 and month 12 post MI,to obtain PBMCs and plasma. Longitudinal flow cytometry analyses were performed to monitor the relative frequencies of total B cells (singlets, live CD45+ CD19+), naïve B cells (CD38-CD27-), memory B cells (CD27+ CD38-) and plasmablasts (CD27+CD28+). The MI patients showed a heterogenous response in terms of circulating B cell compartiments, but a stark increase in the frequencies of circulating Plasmablast was observed on day 5 on 4/10 patients post-MI. Next, plasma samples from the MI patients were incubated with induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM) and the presence of cardiomyocyte-reactive antibodies was detected with fluorochrome-conjugated anti-human IgGs (indirect immunofluorescence). This approach revealed the presence of heart-reactive antibodies in 4/10 MI patients, in contrast to absent reactivity in healthy control patients. Complementary, plasma samples were incubated with iPSC-CM protein extract that have been separated by molecular weight in a modified immunoblot assay. This assay revealed that 7/10 MI patients exhibited cardiac antibody reactivity, in contrast to non-specific reactivity healthy controls. Each responder MI patient showed a distinct and non-overlapping reactivity profile, against proteins with different molecular weights. Within these findings it was a noticeably discovery that the heart specific antibody antigen reactivity of the patient samples was present since the day of the ischemic event and was constantly visable for all of the other timepoints.
Conclusion: Our findings confirm that some MI patients show a rapid mobilization / expansion of circulating plasmablasts concomitant with the production of heart-reactive antibodies. All responder patients showed antibody reactivity already at index hospitalization, suggesting that cardiac autoimmune responses precede the MI. A possible connection to atherogenesis process might be investigated in the future.