ANCA Vasculitis - Types, Causes, Symptoms, and Treatment

What Is ANCA Vasculitis?

ANCA vasculitis is an autoimmune condition that affects the blood vessels. ANCA can be expanded to anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV). This condition occurs when certain antibody receptors bind to immune cells called neutrophils. This binding can over-activate the immune system leading to a series of reactions. Neutrophils, the immune cells, affect the body's small blood vessels. This can cause inflammation of the blood vessels. Inflammation is the body’s defense mechanism that helps remove the threat to the body. The effect of this reaction can be felt in various parts of the body, such as the stomach, kidneys, skin, and intestines. The symptoms of AAV can vary depending on its location. This immune system overreaction is believed to be genetic and environmentally acquired. Depending on the symptoms and other factors, such as microscopic observation, this condition can be classified into three main sub-categories.

What Are the Types of AAV?

ANCA vasculitis can be subdivided into three main categories. This classification is achieved based on the symptoms coupled with microscopic findings. This classification helps in the treatment of the condition. The classification of AAV is as follows:

• Microscopic Polyangiitis (MPA): MPA patients ordinarily experience various side effects like kidney conditions, skin conditions, and nerve injury. This condition is frequently associated with recurrent fever and weight loss. MPO-ANCAs is the antibody that is associated with MPA.

• Granulomatosis With Polyangiitis (GPA): This condition is characterized by the formation of granulomas in the blood vessels. Granulomas are a group of immune cells that attach to the lining of the blood vessels. This type of AAV was also known as Wegener's granulomatosis. Patients with this condition have damage to the blood vessels of various organs such as kidneys, lungs, and respiratory organs.

• Eosinophilic Granulomatosis With Polyangiitis (EGPA): This category of AAV affects only the gastrointestinal and respiratory systems. Other organs can be affected, but it is very rare. Clusters of immune cells called granulomas also cause this condition. One variation in this type of AAV is that the immune clusters are primarily made of eosinophils, not neutrophils. Eosinophils are also a type of immune cell. This condition presents with asthma-like symptoms hence its diagnosis may be difficult. Accurate diagnosis of this condition is possible only through microscopic examination.

What Is the Occurrence of AAV?

This condition is not very uncommon. AAV is known to affect at least one out of every 50,000. This condition affects both men and women equally. More cases were reported in the middle-aged population. While considering racial predilection, this condition most commonly affects the white population.

What Is Meant by Autoimmune Condition?

In absolutely healthy individuals, the immune framework recognizes unfamiliar trespassers and produces antibodies that kill them before they can cause any harm to the body. An autoimmune condition occurs when the insusceptible framework produces unusual autoantibodies that target sound cells and tissue. In AAV, autoantibodies called ANCAs are found at raised levels and attached to immune cells called neutrophils. This causes the accentuation of neutrophils, which then, at that point, are attached to the lining of the veins and discharge harmful granules. This activates the immune response leading to damage to the vasculature, causing swelling. Antibodies focusing on the proteinase 3 (PR3) or the myeloperoxidase (MPO) proteins on neutrophils are the most widely recognized ANCAs in individuals with AAV, each subsequent in unmistakable sickness signs. Rarely can ANCAs target other proteins as well.

What Are the Causes of AAV?

There is no single reason for the occurrence of this condition. This condition can be caused by a single source or can occur due to a mixture of various factors. The causes can be genetic, environmental, or even an infection. The factors causing AAV include the following:

• Genetic: Genetic factors have the strongest association with AAV. The alterations in genetic factors such as the MHC (major histocompatibility complex) are believed to cause this condition. Any alterations to MHC can alter the protein structure of the antibodies produced. These alterations to the MHC can happen through familial inheritance or even mutations.

• Silica Inhalation: Silica is a metal found in various places and materials. Inhalation of silica can affect a person’s respiratory system. It is believed that silica, when inhaled in greater amounts, can stimulate the occurrence of AAV. Silica can be found in asbestos sheets, pesticides, and industrial chemicals.

• Cocaine: Prolonged use of cocaine can have various detrimental effects on health. AAV is one of them. The exact link between cocaine misuse and AAV is not completely understood. However, cocaine users were found to be affected by AAV.

• Infections: Certain bacterial or viral infections have been known to be a prelude to AAV. After the infection by an organism, it is known that the body is on high vigil. This can cause the immune system to overreact. This can, in turn, lead to autoimmune conditions such as AAV.

What Are the Symptoms of AAV?

AAV is known to affect various parts of the body. Hence, the symptoms of AAV depend on the organ affected. Therefore, the various symptoms of AAV according to the system affected may include the following:

Renal Symptoms: When AAV affects the renal system, the following effects may be seen in the kidneys.

1. Blood in the urine.
2. Change the urine color to brown.
3. Foamy urine.
4. Elevated blood pressure due to the effect on the renal vasculature.

Respiratory Symptoms: When AAV affects the respiratory system, it may cause trachea inflammation. The symptoms may include difficulty breathing, changes in voice, continuous cough, sinus infections, ear infections, and discharges from the nose.

Nervous System Symptoms: Nervous system symptoms may include

1. Weakness of the muscles.
2. Tingling sensation.
3. Numbness in the affected region.
4. Pricking-like sensation.
5. Frequent headaches and dizziness.
6. Seizures are also possible in some cases.

Gastrointestinal Symptoms: When AAV affects the stomach, the symptoms may include:

1. Stomach aches and cramps.
2. Nausea and vomiting.
3. Watery stools or diarrhea.
4. Blood in feces.
5. Weight loss without any apparent reason.

Muscular Symptoms: Muscular symptoms may include muscular weakness, cramps, and severe pain.

How Is AAV Diagnosed?

• A doctor can diagnose AAV by reviewing the physical and laboratory findings. The lab tests help identify the type of AAV that aids in its diagnosis. Blood and urine analyses will be performed to obtain a definitive result. Sometimes the doctor may even perform a biopsy of the vascular tissues to check for granuloma formation.

• The doctor may suggest imaging studies to substantiate the blood and urine analyses. The imaging studies may include X-rays and CT (computed tomography) scans. Depending on the need, the patient may also require other specific tests, such as endoscopy or bronchoscopy.

How Is AAV Treated?

• While there is no single solution for AAV, various medications are accessible to deal with the condition. These decrease and, at times, resolve the vascular inflammation and the associated swelling.

• Patients ordinarily go through two treatment periods. The first one usually aims at resolving the condition at hand. The second treatment is a maintenance treatment that aims at preventing recurrence.

• The medicines utilized greatly rely upon sickness seriousness and subtype, yet most are intended to bring down the overactive immune system. This type of treatment usually involves the usage of steroids such as Methotrexate, Corticosteroids, and Rituximab.

Conclusion:

AAV is one such medical condition that does not have any specific causes or symptoms. It is believed to be caused due to a mix of genetic and environmental factors. It affects various body systems, such as the lungs, gastrointestinal, and kidneys. Most of its symptoms can overlap with the symptoms of various other conditions. Hence, a medical opinion should be obtained soon if any of the above-mentioned symptoms are observed.