Lupus nephritis is an

inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...

of the

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...

s caused by

systemic lupus erythematosus Lupus, technically known as systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Commo ...

(SLE), an

autoimmune disease An autoimmune disease is a condition arising from an abnormal immune response to a functioning body part. At least 80 types of autoimmune diseases have been identified, with some evidence suggesting that there may be more than 100 types. Nearly a ...

. It is a type of

glomerulonephritis Glomerulonephritis (GN) is a term used to refer to several kidney diseases (usually affecting both kidneys). Many of the diseases are characterised by inflammation either of the glomeruli or of the small blood vessels in the kidneys, hence the ...

in which the glomeruli become inflamed. Since it is a result of SLE, this type of glomerulonephritis is said to be ''secondary'', and has a different pattern and outcome from conditions with a ''primary'' cause originating in the kidney. The diagnosis of lupus nephritis depends on

blood test A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose test or a choles ...

urinalysis Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic e ...

, X-rays,

ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...

scans of the kidneys, and a

kidney biopsy Renal biopsy (also kidney biopsy) is a medical procedure in which a small piece of kidney is removed from the body for examination, usually under a microscope. Microscopic examination of the tissue can provide information needed to diagnose, m ...

. On urinalysis, a nephritic picture is found and red blood cell casts,

red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "hol ...

s and

proteinuria Proteinuria is the presence of excess proteins in the urine. In healthy persons, urine contains very little protein; an excess is suggestive of illness. Excess protein in the urine often causes the urine to become foamy (although this symptom ma ...

is found.

Classification

The

World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...

has divided lupus nephritis into five stages based on the biopsy. This classification was defined in 1982 and revised in 1995. Class IV disease ( Diffuse proliferative nephritis) is both the most severe, and the most common subtype. Class VI (advanced sclerosing lupus nephritis) is a final class which is included by most practitioners. It is thought to be due to the chronic

interferon Interferons (IFNs, ) are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten th ...

exposure.

Membranous nephropathy - mpas - very high mag

A tubuloreticular inclusion within capillary endothelial cells is also characteristic of lupus nephritis and can be seen under an electron microscope in all stages. It is not diagnostic however, as it exists in other conditions such as HIV infection.

Signs and symptoms

General symptoms of lupus nephritis include

Cause

The cause of lupus nephritis, a genetic predisposition, plays a significant role in lupus nephritis. Multiple

genes In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

, many of which are not yet identified, mediate this genetic predisposition. The

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

protects the human body from

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...

, and with immune system problems it cannot distinguish between harmful and healthy substances. Lupus nephritis affects approximately 3 out of 10,000 people.

Pathophysiology

The

pathophysiology Pathophysiology ( physiopathology) – a convergence of pathology with physiology – is the study of the disordered physiological processes that cause, result from, or are otherwise associated with a disease or injury. Pathology is ...

of lupus nephritis has

autoimmunity In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an "autoimmune disease". ...

contributing significantly. Autoantibodies direct themselves against nuclear elements. The characteristics of nephritogenic autoantibodies (lupus nephritis) are

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune respon ...

specificity directed at

nucleosome A nucleosome is the basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone proteins and resembles thread wrapped around a spool. The nucleosome is the fundame ...

, high affinity autoantibodies form intravascular immune complexes, and autoantibodies of certain isotypes activate

complement A complement is something that completes something else. Complement may refer specifically to: The arts * Complement (music), an interval that, when added to another, spans an octave ** Aggregate complementation, the separation of pitch-clas ...

Treatment

Drug regimens prescribed for lupus nephritis include

mycophenolate mofetil Mycophenolic acid (MPA) is an immunosuppressant medication used to prevent rejection following organ transplantation and to treat autoimmune conditions such as Crohn's disease and lupus. Specifically it is used following kidney, heart, and liv ...

(MMF), intravenous

cyclophosphamide Cyclophosphamide (CP), also known as cytophosphane among other names, is a medication used as chemotherapy and to suppress the immune system. As chemotherapy it is used to treat lymphoma, multiple myeloma, leukemia, ovarian cancer, breast cancer ...

with corticosteroids, and the immune suppressant

azathioprine Azathioprine (AZA), sold under the brand name Imuran, among others, is an immunosuppressive medication. It is used in rheumatoid arthritis, granulomatosis with polyangiitis, Crohn's disease, ulcerative colitis, and systemic lupus erythematosus, ...

with

corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are inv ...

s. MMF and cyclophosphamide with corticosteroids are equally effective in achieving remission of the disease, however the results of a recent systematic review found that

immunosuppressive drug Immunosuppressive drugs, also known as immunosuppressive agents, immunosuppressants and antirejection medications, are drugs that inhibit or prevent activity of the immune system. Classification Immunosuppressive drugs can be classified int ...

s were better than corticosteroids for renal outcomes. MMF is safer than cyclophosphamide with corticosteroids, with less chance of causing ovarian failure, immune problems or hair loss. It also works better than azathioprine with corticosteroids for maintenance therapy. A 2016 network meta-analysis, which included 32 RCTs of lupus nephritis, demonstrated that

tacrolimus Tacrolimus, sold under the brand name Prograf among others, is an immunosuppressive drug. After allogeneic organ transplant, the risk of organ rejection is moderate. To lower the risk of organ rejection, tacrolimus is given. The drug can also ...

and MMF followed by

maintenance were associated with a lower risk of serious infection when compared to other immunosuppressants or glucocorticoids. Individuals with lupus nephritis have a high risk for B-cell lymphoma (which begins in the immune system cells).

Prognosis

In those who have SLE, concomitant lupus nephritis is associated with a worse overall prognosis. 10-30% of people with lupus nephritis progress to kidney failure requiring dialysis, with the 5 year mortality rate of lupus nephritis being 5-25%. The proliferative forms of lupus nephritis are associated with a higher risk of progression to end stage kidney disease. Black and Hispanic people with lupus nephritis are more likely to present with severe disease at initial presentation (with more proteinuria and more extensive histopathologic changes) and progress to end stage kidney disease. This is thought to be due to socioeconomic factors but auto-antibodies strongly associated with lupus nephritis such as anti-Sm, anti-Ro and anti-ribonucleoprotein are also more commonly seen in Black and Hispanic people. Men with SLE tend to have more aggressive forms of lupus nephritis as well with a higher risk of progression to end stage kidney disease and higher risk of concurrent cardiovascular disease.

References

External links

{{Glomerular disease Rheumatology Kidney diseases