Definitions for every part
of the IgAN chain reaction

APRIL (A PRoliferation-Inducing Ligand) is an immune messenger (cytokine). APRIL plays a central role in IgA nephropathy.

In IgAN, the cytokine APRIL can tell B cells (a type of blood cell that is part of the immune system) to produce an abnormal antibody called Gd-IgA1.

The abnormal antibody Gd-IgA1 is the first step in the chain reaction known as the 4-hit process. This can lead to kidney damage.

An autoantibody is an antibody (immune defense factor) that targets the body’s own tissues and substances.

Antibodies are specialized proteins that the immune system uses to fight infections.

In IgA nephropathy, autoantibodies are made that can bind to the abnormal antibody called Gd-IgA1.

These autoantibodies bind together with Gd-IgA1 to form clusters (immune complexes) that can become lodged in the kidneys, causing inflammation and triggering further kidney damage.

B cells are a type of blood cell that produces antibodies.

B cells are part of the immune system. In IgA nephropathy, the cytokine called APRIL signals B cells to produce IgA, including Gd-IgA1, an abnormal antibody that can contribute to kidney inflammation and damage.

Berger’s disease is another name for IgA nephropathy.

Jean Berger, a French nephrologist, along with Nicole Hinglais, were the first people to describe the disease in 1968.

A biopsy is a procedure in which a small sample of kidney tissue is removed for examination.

In IgA nephropathy, a biopsy is the only way to definitely confirm an IgAN clinical diagnosis.

Kidney biopsies can also help confirm the presence of the abnormal antibody called Gd-IgA1 and autoantibodies in the kidney and determine how much kidney damage has been caused by this progressive, chronic, autoimmune kidney disease.

A blood urea nitrogen (BUN) test is a blood test that measures the amount of urea, a waste product, in your blood. High levels can signal your kidneys aren’t filtering properly.

An autoimmune disease occurs when the immune system attacks the body’s own tissues. Many autoimmune diseases are chronic conditions, which means they will probably have to be managed for the rest of a person’s life. IgA nephropathy is called a kidney disease because it involves autoimmune activity that leads to kidney damage. In IgA nephropathy, the immune system targets the abnormal antibody called Gd-IgA1. This leads to autoantibodies being made that attack Gd-IgA1.

Chronic kidney disease (CKD) is a long-term condition where the kidneys gradually lose their ability to filter blood. IgA nephropathy is a leading cause of CKD.

The complement system is a part of the immune system that enhances the body’s defense against infections. It can also contribute to inflammation.

In IgA nephropathy, it is activated by immune complexes (clusters) formed by the abnormal antibody Gd-IgA1 and autoantibodies grouping together.

This can lead to increased inflammation and kidney damage.

The complement pathway, a key component of the complement system, plays a role in driving immune responses.

When activated, it may contribute to the progression of IgA nephropathy by worsening kidney inflammation and injury.

Cytokines are small proteins that help your immune system communicate with the rest of your body.

APRIL is a cytokine that plays a key role in IgA nephropathy by promoting the constant production of the abnormal antibody called Gd-IgA1, which can lead to kidney damage.

Dialysis is a treatment that helps remove waste products from the blood when the kidneys can no longer perform this function. In IgA nephropathy, dialysis may be needed if the kidneys fail due to long-term damage from the disease.

eGFR (estimated glomerular filtration rate) is a measure of kidney function.

It estimates how well your kidneys are filtering your blood. Monitoring eGFR gives doctors additional information about how the kidneys are functioning.

This measurement, alongside others, helps nephrologists to assess the progression of IgA nephropathy.

ESKD (end-stage kidney disease) is the final stage of kidney disease where the kidneys lose nearly all their function.

If not properly managed, IgA nephropathy can progress to ESKD due to ongoing kidney damage.

Over time, this damage can lead to kidney failure, which may lead to dialysis or the need for a kidney transplant.

Fatigue is a common symptom of kidney disease, including IgA nephropathy. It can result from waste buildup in the blood or the development of anemia. Both fatigue and anemia may result from kidney damage.

Fibrosis is the scarring of kidney tissue. In IgA nephropathy, fibrosis develops because of chronic inflammation caused by the abnormal antibody called Gd-IgA1 and autoantibody immune clusters, and it can lead to permanent kidney damage and loss of kidney function.

The level of fibrosis in kidneys is assessed using a kidney biopsy.

Gd-IgA1 (galactose-deficient IgA1) is an abnormal antibody produced in IgA nephropathy.

APRIL is a driver of the production of Gd-IgA1, which triggers the 4-hit process and can cause kidney inflammation and damage.

The glomerulus is a part of the nephron that filters blood in the kidneys, like a small sieve.

In IgA nephropathy, Gd-IgA1 and autoantibody immune complexes (clusters) get trapped in the glomerulus, causing inflammation (glomerulonephritis).

This can lead to kidney damage and loss of kidney function.

Glomerulonephritis is inflammation of the glomeruli, the kidney’s filtering units.

In IgA nephropathy, glomerulonephritis occurs when Gd-IgA1 immune complexes become trapped in the kidneys, straining function and causing inflammation. This can lead to kidney damage and loss of kidney function.

Hematuria, or blood in the urine, is a common symptom of IgA nephropathy. It occurs when Gd-IgA1 immune complexes damage the kidney’s filters, allowing red blood cells to leak into the urine. When there is a lot of blood in the urine, the urine may be pink or cola-colored.

Hematuria, or blood in the urine, is another marker of kidney damage in IgA nephropathy.

It can occur when the kidney’s filters are damaged by immune complexes (clusters) containing Gd-IgA1 and autoantibodies.

High blood pressure refers to an increase in the amount of force that blood places on blood vessels as it moves through the body. Your kidneys help regulate your blood pressure.

IgA1 is a type of antibody that helps protect the body against infections.

In IgA nephropathy, an abnormal form of IgA called Gd-IgA1 is produced and can contribute to kidney damage and disease progression.

IgA nephropathy is a progressive, chronic, autoimmune kidney disease where the immune system produces an abnormal form of IgA called Gd-IgA1.

This abnormal antibody causes kidney inflammation and damage and can lead to progressive kidney disease.

An immune complex forms when Gd-IgA1 binds with autoantibodies, creating clusters that get trapped in the kidneys.

This triggers inflammation and damage in the kidneys and can lead to disease progression in IgA nephropathy.

An immune response is the body’s reaction to what it perceives as a threat.

In IgA nephropathy, the immune system targets Gd-IgA1. This can eventually lead to kidney damage and loss of kidney function.

The immune system works to keep germs and other foreign substances out of the body and tries to destroy any that get in.

It’s made up of a complicated network of cells and organs.

It protects the body from infection, cancer, and other conditions.

Inflammation in IgA nephropathy is caused by immune complexes (clusters), of the abnormal antibody called Gd-IgA1 and autoantibodies, that become trapped in the kidneys.

This inflammation can lead to scarring, and eventually kidney damage and loss of kidney function.

A kidney transplant involves replacing damaged kidneys with healthy ones from a donor.

It may be a necessity for individuals with IgA nephropathy who reach end-stage kidney disease (ESKD) due to damage caused by the disease.

A nephron is the basic functional unit of the kidney.

It is responsible for filtering blood and producing urine.

Damage to nephrons in IgA nephropathy can impair the kidneys’ ability to filter blood properly.

Nephron damage in IgA nephropathy occurs when immune complexes (clusters), made up of the abnormal antibody Gd-IgA1 and autoantibodies, get stuck in the kidneys.

This damage can impair the nephrons’ ability to filter blood and regulate fluid balance.

Potassium is an essential mineral that the body needs to function properly. In IgA nephropathy, you may need to watch your potassium intake to help prevent extra strain on your kidneys, since they are responsible for maintaining the right potassium balance in your blood.

Proteinuria is the presence of excess protein in the urine, often a sign of kidney damage. Foamy urine may be a sign of proteinuria.

In IgA nephropathy, proteinuria occurs when Gd-IgA1 immune complexes damage the kidneys’ filters.

Proteinuria is a key marker of kidney damage in IgA nephropathy.

As Gd-IgA1 clusters cause damage to the kidneys’ filters, protein can leak into the urine, indicating impaired kidney function.

Renal refers to anything related to the kidneys.

Renal function is often monitored in IgA nephropathy since the disease can progressively impair the kidneys’ ability to filter waste and regulate fluid balance.

Scarring, or fibrosis, occurs because of chronic kidney inflammation in IgA nephropathy.

Abnormal antibody immune clusters cause lasting damage to the kidneys’ filtering structures (glomeruli), leading to scarring and eventual loss of kidney function.

The level of scarring in kidneys is assessed using a kidney biopsy.

The 4-hit process is a sequence of immune system events that lead to kidney damage in IgA nephropathy.

APRIL is one of the main drivers of the harmful chain reaction known as the 4-hit process. It starts the production of Gd-IgA1, leading to an inflammatory response that can damage kidneys over time that is irreversible.

Sodium is a chemical element found in nature and in the body. Sodium is essential for life and plays a key role in nerve function and fluid balance in living organisms. Your kidneys help tightly regulate the levels of sodium in your blood.

Supportive care includes measures to help manage symptoms and slow disease progression.

This may involve blood pressure control, medications to reduce proteinuria, and lifestyle changes to protect kidney health.