Lupus Nephritis

Lupus nephritis is an autoimmune disease that is caused by systematic lupus erythematous (SLE) and causes inflammation of the kidneys.1 Normally, the immune system is supposed to protect the human body from harmful and infectious elements. However, an autoimmune disease affects the immune system in a manner in which it cannot tell the difference between a healthy and harmful substance, which can lead to attacks on healthy cells and tissue indiscriminately.2 It is a disease that predominately afflicts women between the ages of 15 and 40 and affects 1 in 2,000 women within the United States.3 It was reported that African Americans are more susceptible to lupus nephritis, the disease is developed at a younger age, and are predisposed to end-stage kidney disease.4 Currently, there is no cure for the disease but treatment options are available for those that are affected.

Lupus nephritis is one of the most serious complications of SLE as it significantly affects the kidney and usually arises within 5 years of diagnosis.5 It occurs when "lupus autoantibodies affect the filtering structures (glomeruli) of your kidneys that results in kidney inflammation and may lead to blood in the urine, (hematuria), protein in the urine (proteinuria), impaired kidney function or even kidney failure."6

Lupus nephritis is categorized into six World Health Organization classes: I, normal; II, mesangial; III, focal proliferative; IV, diffuse proliferative; V, membranous; and VI, advanced sclerosing.3 Each class of lupus nephritis is examined in further detail below.

Class I. This class is defined as "minimal mesangial lupus nephritis with mesangial accumulation of immune complexes identified by immunofluorescence, or by immunofluorescence and electron microscopy, without concomitant light microscopic alterations."7

Class II. Class II is defined as mesangial lupus nephritis is characterized by "any degree of mesangial hypercellularity in association with mesangial immune deposits."7

Class III. Defined as focal lupus nephritis, this class involves less than 50% of all glomeruli, in which afflicted glomeruli are shown to have "segmental endocapillary proliferative lesions or inactive glomerular scars, with or without capillary wall necrosis and crescents, with subendothelial deposits."7

Class IV. This class is defined as diffuse lupus nephritis, which involves more than 50% of the glomeruli. The affected glomeruli are exposed to the same conditions as Class III along with the lesions being segmental.7

Class V. Class V is called membranous lupus nephritis and involves "global or segmental continuous granular subepithelial immune deposits, often with concomitant mesangial immune deposits."7

Class VI. In Class VI, the disease transitions into advanced-stage lupus nephritis in which biopsies have 90% or greater global glomerulosclerosis and that there is evidence of lupus nephritis causing sclerosis.7

The exact cause of lupus is not known. However, there are some causative factors of lupus nephritis, including environmental factors, viral infections, gender and genetics. Exposure to UV rays (particularly from sunlight) and chemical substances are known to trigger symptoms and could play a role in the development of the disease.1 Viral infections, including the one that causes mononucleosis, can also trigger lupus attacks. In regards to gender, lupus nephritis affects women with a ratio of 9:1.4 The reason why women may be so predisposed to lupus nephritis could be related to hormones, as women that are affected with this disease have much higher levels of estrogen and progesterone.1 Another risk factor is genetics.

According to a study conducted, there is evidence suggesting that genetic predisposition plays an important role in the development of both SLE and lupus nephritis.5 The disease is more prevalent in first-degree relatives of those affected, with a concordance rate of 10-12%.5 The concordance rate is much higher