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(Hypertension. 1999;34:e10.)
© 1999 American Heart Association, Inc.
Letters to the Editor - Web |
Regulatory Natural Antibodies in Hypertension?
Department of Physiology, Institute of Postgraduate Studies, Universiti Malaya, Lumpur, Malaysia
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To the Editor:
We read with interest the recent report by Wu et al1 on the reduction of both IgG and IgM autoantibodies to oxidized LDL (OxLDL) in individuals with borderline hypertension compared with normotensive controls. We would like to extend the implication of their data with results from our own studies of natural antibodies in healthy persons.
We recently detected in all normal human serum (NHS), natural antibodies to oxysterols (including cholesterol epoxide, 7keto-, 19hydroxy-, and 7hydroxy- cholesterol), which are main components of LDL that have undergone oxidative modification.2 The consistent presence of anti-oxysterol (and by extension, anti-OxLDL) was postulated to be important in regulating the concentration and bioactivity of OxLDL (which comes from either a dietary source or from in vivo oxidation3 ), which is thought to be involved in endothelial dysfunction and other events in the atherogenic process. The lowered serum anti-OxLDL in Wu et al’s study might therefore be related to this suggestion.
An additional role of natural antibodies in regulating blood pressure is also indicated by the finding of natural antibodies that recognize renin, angiotensin II, and catecholamines.4 5 6 Diet appears to influence this natural humoral immunoreactivity. We have also observed autoantibodies to aldosterone in normal subjects. In an ELISA system, all eleven NHS that were tested contained specific IgG and IgA, and 8 of the 11 sera also had IgM antialdosterone antibodies (S.A. et al, unpublished data, 1999).
Natural antibodies are thought to function as immunotransporters in addition to being involved in the physiological clearance of aged molecules and cell membrane fragments.7 The natural antibody binding of hormones involved in vascular and blood volume control of arterial pressure may serve to modulate and maintain an appropriate hormonal level amidst physiological fluctuations. Dietary determinants that affect blood pressure may thus act through antioxidative/pro-oxidative factors and vascular modulators as well as the level of natural antibody activity.8 9 It would be of interest if Wu and coworkers could also analyze their hypertensive serum samples for autoantibodies to some of the above hormones.
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1. Wu R, De Faire U, Lemne C, Witztum JL, Frostegard J. Autoantibodies to OxLDL are decreased in individuals with borderline hypertension. Hypertension. 1999;33:53–59.
2. Cheng HM, Sundram K. Cholesterol oxides and natural autoantibodies. Artherosclerosis. 1998;141:347–348.
3. Osada K, Inoue T, Nakamura S, Sugano M. Dietary soybean protein moderates the deleterious disturbance of lipid metabolism caused by exogenous oxidised cholesterol in rats. Biochim Biophys Acta. 1999;1427:337–350.[Medline] [Order article via Infotrieve]
4.
Castedo M, Pelletier L, Pasquier R, Guettier C, Huygen
K, Michel JB, Druet P. Anti-renin T cells trigger normal B cells to
produce anti-renin antibodies and normalize blood pressure in
spontaneous hypertensive rats. Int Immunol. 1993;12:1569–1576.
5. Pogozheva AV, Rozanova IA, Miagkova MA, Sorokovoi KV, Panchenko ON, Trubacheva ZN. Effect of antiatherosclerotic diet enriched with polyunsaturated omega-3 fatty acids on the level of natural antibodies to catecholamines in patients with cardiovascular diseases [in Russian]. Vopr Pitan. 1998;4:32–35.
6. Rozanova IA, Pogozheva AV, Miagkova MA, Savitskaia IA. Effect of anti-atherosclerotic diet with polyunsaturated omega-3 fatty acids on natural antibodies to bradykinin and angiotensin II in patients with cardiovascular diseases [in Russian]. Vopr Pitan. 1998;2:32–34.
7. Cheng HM. Natural cryptic antibodies. Autoimmunity. 1998;27:99–108.[Medline] [Order article via Infotrieve]
8. Sata M, Walsh K. Oxidised LDL activates Fas-mediated endothelial cell apoptosis. J Clin Invest. 1998;102:1682–1689.[Medline] [Order article via Infotrieve]
9.
Cheng HM, Sundram K. Oxidised LDL, diet and natural
antibodies. Amer J Clin Nutr. 1999;70:104–105.
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