This review evaluates the role of autoimmune response as a cause of hypertension.

This review evaluated new theories regarding the role of the immune response as a cause of hypertension.

There are multiple causes of hypertension (high blood pressure), including damage to the blood vessels and to the kidneys. Because there are a variety of causes, there is no one treatment that works for all patients. Finding the appropriate treatment depends on understanding the underlying cause.

Recent evidence has suggested that hypertension may also be caused by an autoimmune response (in which the immune system attacks healthy body tissue). Blood pressure is partially controlled by angiotensin 2 type 1 receptors (AT1). When AT1 receptors are activated, blood pressure increases. An autoimmune response can produce agonistic autoantibodies (AT1-AA), which cause the AT1Rs to become overactive, leading to increased blood pressure.  The current review examines the role AT1-AA plays as a cause of hypertension and how this knowledge can direct treatments.

Various factors are known to be associated with the development of hypertension (high blood pressure), but in many cases the cause of hypertension remains unknown. Since medical ability to control hypertension is still limited, and many patients remain uncontrolled despite optimal treatment, research aimed at understanding new mechanisms behind the development of the disease is of high importance.

Recent evidence suggests that an autoimmune response, in which the immune system responds to normal, healthy tissue, is associated with the development of hypertension. Blood pressure is known to be controlled in part by angiotensin 2 type 1 (AT1) receptors. When AT1 receptors are activated, blood pressure increases. An autoimmune response and production of antibodies which stimulate the AT1 receptors (referred to as AT1 auto-antibodies, or AT1-AA), is a possible cause for the development of hypertension. The current review examined the role AT1-AA in the development of hypertension and how this knowledge can help direct treatment.

AT1-AA was originally discovered to play a key role in preeclampsia, or hypertension during pregnancy. It has since been found to be involved in hypertension outside of pregnancy as well. AT1-AA was found in 59% of patients with refractory hypertension (hypertension that does not respond to treatment). Patients with higher blood pressures were found to have higher levels of AT1-AA.

Detecting AT1-AA in a patient can help to direct hypertension treatment. AT1-AA raises blood pressure by overactivating the AT1 receptors. Research has shown that blocking these receptors with drug treatments such as angiotensin receptor blockers (ARBs) can be more effective at lowering blood pressure than other common hypertension treatments, such as ACE inhibitors (which do not affect the AT1 receptors). 

AT1-AA was originally discovered as a cause of preeclampsia, or hypertension during pregnancy. It has since been found to be associated with hypertension outside of pregnancy as well. One study reports that AT1-AA were found in 59% of patients with refractory hypertension (hypertension that does not respond to medical treatment). A similar study has reported that patients with higher blood pressure values were also found to have higher levels of AT1-AA in their blood.

Over recent years, drugs that block the action of the AT1 receptors, also referred to as angiotensin receptor blockers (ARBs) have been prescribed to hypertensive patients with increasing popularity. However, ARB's are one of many drugs used in the treatment of hypertension. Not all hypertensive patients are necessarily treated with ARB's, and many patients remain uncontrolled without ever attempting the use of this class of drug.

This review concludes that an autoimmune response can be an important cause of hypertension. This review also highlights the importance of understanding the underlying cause of hypertension in order to best determine treatments for the specific needs of the patient.

This review concluded that an autoimmune response involving AT1-AA is found in many cases of uncontrolled hypertension. The exact role of AT1-AA in the development of hypertension, and which patients could benefit most from the use of angiotensin receptor blockers, is deserving of thorough investigation.