Hypertension vaccine

Many heart attacks, strokes, hypertensive crises and other consequences of high blood pressure could have been avoided if all hypertensive patients punctually followed doctors' prescriptions about the need for constant intake of medications that reduce blood pressure.

A key role in the blood pressure regulation system belongs to angiotensin II, which stimulates the contraction of blood vessels. It also stimulates the synthesis of a hormone that promotes the retention of water and sodium ions in the body, which further increases blood pressure. For the treatment of hypertension, in addition to diuretics that promote the excretion of water, angiotensin II receptor blockers are traditionally used, which reduce the sensitivity of blood vessel smooth muscle cells to angiotensin, and inhibitors of the angiotensin converting enzyme necessary for its synthesis.

Scientists of the Swiss biotech company Cytos have created a vaccine, the introduction of which 2-3 times a year can replace the use of traditional antihypertensive drugs and make life easier for millions of hypertensive patients. The new vaccine also acts on angiotensin II, but its effects are much more long-term compared to the effects of traditional drugs.

The vaccine consists of virus–like particles (blue in the figure) covered with receptors (yellow) that bind angiotensin II molecules when they enter the bloodstream. The immune system, attacking an obviously viral particle, stumbles upon the angiotensin II molecules covering it, and after vaccination, part of the immune cells in the body continues to destroy the angiotensin molecules they encounter in the bloodstream.

The developers tested their vaccine on 72 patients with hypertension – moderate and severe. The test participants were randomly divided into 3 groups, one of which received a low dose of the vaccine, the second – a high dose, and the third – a placebo. The day before the drug was administered, to obtain information about the baseline blood pressure level, each participant was provided with a sensor that registers pressure every 15 minutes for 24 hours.

Repeated vaccinations of patients were carried out one and three months after the initial administration of the drug. Throughout the trial period, participants reported all side effects by phone. Two weeks after the last vaccination, they used the sensor again to register the pressure level during the day.

Almost all participants tolerated the vaccination relatively well. Among the minimal side effects observed, some noted flu-like symptoms and mild irritation at the injection site.

The most pronounced decrease in blood pressure was observed when large doses of the vaccine were administered. During the day and at night, the pressure level in all patients remained almost constant, and in the early morning (which doctors did not expect) there was a pronounced decrease in pressure. Perhaps this is due to the fact that at night the body produces a small amount of angiotensin II molecules, the antibodies synthesized by immune cells are practically not consumed during this period and cope with their function more effectively in the morning.

According to Martin Bachmann, head of the Cytos research department, lowering blood pressure in the morning reduces the risk of heart attacks and strokes, often developing in the morning, when people usually have a sharp increase in blood pressure, and medications taken before bedtime already lose their activity. In any case, a vaccine that has been active for a long period of time is an attractive alternative to the daily medication regimen, which many patients do not adhere to.

However, there are a number of questions regarding the long-lasting and potentially irreversible effect of the vaccine. It must be remembered that in everyday life, situations regularly arise in which an increase in pressure is necessary – for example, when climbing stairs and other physical exertion. In addition, it is unclear what effect the constant stimulation of the immune system will have on the production of antibodies against the body's own protein. At the same time, Bachman claims that the analysis of blood samples of participants in clinical trials of the vaccine did not reveal any changes in the state of the immune system.

In the coming months, Cytos plans to find a pharmaceutical partner to conduct more extensive trials of the vaccine and work on selecting its optimal dosages, including for patients with mild forms of hypertension.

Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of TechnologyReview

17.03.2008