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Cardiovascular involvement in human and experimental leptospirosis: pathologic findings and immunohistochemical
T de Brito1, C F Morais, P H Yasuda
1Faculty of Medicine, Department of Pathology, University of São Paulo, Brazil.
Insights
Leptospirosis causes inflammation in heart tissues, including myocarditis and coronary arteritis, and affects major blood vessels. These findings suggest leptospirosis is a systemic vasculitis impacting the cardiovascular system.
Area of Science:
- Cardiovascular Pathology
- Infectious Diseases
- Medical Microbiology
Background:
- Leptospirosis is a zoonotic disease with potential systemic manifestations.
- The cardiovascular impact of leptospirosis, particularly in severe cases, requires further elucidation.
Purpose of the Study:
- To investigate the cardiac and vascular pathology in human leptospirosis cases.
- To correlate histopathological findings with the presence of Leptospira interrogans.
- To examine the effects of experimental Leptospira infection on cardiac tissue.
Main Methods:
- Human autopsy hearts (n=20) were examined for myocarditis, conduction tissue inflammation, coronary arteritis, and aortitis.
- Immunohistochemistry was used to detect Leptospira antigen deposits.
- Experimental model using guinea pigs (n=12) inoculated with L. interrogans serovar icterohaemorrhagiae.
Main Results:
- Interstitial myocarditis observed in 50% of cases, correlating with conduction tissue inflammation.
- Acute coronary arteritis found in 70% of cases, significantly associated with myocarditis.
- Aortitis present in 57.8% of cases; Leptospira antigen deposits identified in coronary arteries and aorta.
- Experimental infection induced focal myocarditis and antigen deposition in guinea pigs.
Conclusions:
- Leptospirosis can manifest as a systemic vasculitis affecting the heart and major vessels.
- Inflammation of the myocardium and vasculature is a significant feature of severe leptospirosis.
- Bacterial components or toxins likely contribute to endothelial damage and inflammation during the septicaemic phase.
Abstract:
Twenty hearts from patients dying of leptospirosis were studied. Interstitial myocarditis was found in 50% of the cases, and a significant statistical correlation was observed between myocarditis and the inflammatory involvement of the conduction tissue. Acute coronary arteritis, affecting the main branches of the coronary arteries, was observed in 70% of the cases, and this finding also correlates significantly with interstitial myocarditis. Aortitis was found in 57.8% of the cases. When serum against L. interrogans serovar icterohaemorrhagiae was used, focal IP antigen deposits were observed in the coronary arteries and in the aorta. Experimental data from 12 guinea-pigs inoculated with L. interrogans serovar icterohaemorrhagiae showed a focal myocarditis involving mainly the subendocardial and pericoronary heart tissue, with IP antigen deposits in the same sites. Leptospirosis might be visualized as a generalized illness resembling other infectious vasculitides. The heart and main vessels are involved during the septicaemic phase of the disease, and bacterial migration, toxin(s), enzymes and/or antigenic products liberated by bacterial lysis might account for the increased endothelial permeability with antigen deposits and inflammation.