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It is an autoimmune disorder (type II hypersensitivity reaction) having the presence of antibodies against non-collagenous domain of a3 chain of collagen IV causing destruction of basement membrane in renal glomeruli and pulmonary alveoli.
Life-threatening autoimmune disease that affects the lungs and the kidneys.
The disease affects young men more commonly and is associated with smoking, viral infections or exposure to hydrocarbon solvents (workers in dry cleaning industry).
Cause
- Genetic
- Or the disease may occur because of a combination of other factors.
- These include exposure to certain chemicals, such as dry cleaning chemicals or the weed killer Paraquat. Viral infections, smoking, or medicines may also play a role.
Pathophysiology
- Goodpasture syndrome is due to circulating autoantibodies directed at the glomerular basement membrane.
- The resulting crescentic glomerulonephritis is the result of the antigenantibody complexes that form at the basement membrane.
- The autoantibodies activate the complement system in the basement membrane, causing tissue injury.
- This binding of autoantibodies can be seen as a linear deposition of immunoglobulins along the basement membrane.
- The inflammatory response in that area results in the typical picture of glomerulonephritis.
- The alveolar basement membrane shares the same collagen target as that of the glomerulus. The main component of the basement membrane is type 4 collagen, which can be expressed as six different chains, from alpha 1 to alpha 6.
- Despite the presence of circulating antibodies in anti-glomerular basement membrane disease, pulmonary symptoms are not always observed.
- An inciting lung injury seems to make pulmonary symptoms more likely.
- In a healthy individual, the alveolar endothelium acts as a barrier to the anti-basement membrane antibodies.
- However, if an insult results in increased permeability of the alveolar capillaries, it leads to the trespassing of autoantibodies, which then bind to the basement membrane.
- Strong evidence for genetic involvement exists and patients with certain human leukocyte antigen (HLA) types are found to be more susceptible to disease and exhibit a poor prognosis.
Histologically
- The alveoli show focal necrosis, intra-alveolar hemorrhage, presence of hemosiderin laden macrophages and hypertrophy of type II Pneumocytes.
- The renal involvement is in the form of either focal proliferative or crescentic glomerulonephritis.
- Immunofluorescence studies show linear deposits of immunoglobulins along alveolar septa and GBM
Symptoms
- Coughing up blood,
- Difficulty breathing,
- Nosebleeds
- Fatigue and anemia.
- When the disease affects the kidneys, patients may have blood in the urine, swelling of the legs and high blood pressure.
- If the kidney disease is very severe, patients may notice that they are passing only small amounts of urine and may have nausea and vomiting as well.
Diagnosis
- Blood tests to check how your kidneys are working and look for antibodies in your blood.
- Urine test to check for blood or protein.
- CT scan or chest X-ray to look for lung damage.
- Bronchoscopy to examine your lungs.
- Kidney biopsy, to look for glomerulonephritis (inflammation of the kidneys) and to check for anti-GBM antibodies in the kidney tissue.
Treatment
Immunosuppressive medicines. These medicines keep your immune system from making antibodies. They can also make you at greater risk for infections. So you may also be prescribed antibiotics. |
Corticosteroids. Used to decrease inflammation and tissue damage which helps control bleeding in your lungs. |
Plasmapheresis. This is a process in which blood plasma is removed, cleaned of harmful antibodies, and then returned to your body. It is usually given with steroids. |
