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Research article - Peer-reviewed, 2021

Potential natural immunization against atherosclerosis in hibernating bears

Samal, Shailesh Kumar; Frobert, Ole; Kindberg, Jonas; Stenvinkel, Peter; Frostegard, Johan


Brown bears (Ursus arctos) hibernate for 5-6 months during winter, but despite kidney insufficiency, dyslipidemia and inactivity they do not seem to develop atherosclerosis or cardiovascular disease (CVD). IgM antibodies against phosphorylcholine (anti-PC) and malondialdehyde (anti-MDA) are associated with less atherosclerosis, CVD and mortality in uremia in humans and have anti-inflammatory and other potentially protective properties. PC but not MDA is exposed on different types of microorganisms. We determine anti-PC and anti-MDA in brown bears in summer and winter. Paired serum samples from 12 free ranging Swedish brown bears were collected during hibernation in winter and during active state in summer and analyzed for IgM, IgG, IgG1/2 and IgA anti-PC and anti-MDA by enzyme linked immunosorbent assay (ELISA). When determined as arbitrary units (median set at 100 for summer samples), significantly raised levels were observed in winter for anti-PC subclasses and isotypes, and for IgA anti-PC the difference was striking; 100 IQR (85.9-107.9) vs 782.3, IQR (422.8-1586.0; p<0.001). In contrast, subclasses and isotypes of anti-MDA were significantly lower in winter except IgA anti-MDA, which was not detectable. Anti-PCs are significantly raised during hibernation in brown bears; especially IgA anti-PC was strikingly high. In contrast, anti-MDA titers was decreased during hibernation. Our observation may represent natural immunization with microorganisms during a vulnerable period and could have therapeutic implications for prevention of atherosclerosis.

Published in

Scientific Reports
2021, volume: 11, number: 1, article number: 12120

Authors' information

Samal, Shailesh Kumar
Karolinska Institutet
Frobert, Ole
Orebro University
Norwegian Institute for Nature Research (NINA)
Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies
Stenvinkel, Peter
Karolinska Institutet
Frostegard, Johan
Karolinska Institutet

Sustainable Development Goals

SDG3 Good health and wellbeing

UKÄ Subject classification

Clinical Science

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