Lupus nephritis pathophysiology: Difference between revisions
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Revision as of 03:31, 15 June 2018
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Lupus nephritis Microchapters |
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Lupus nephritis pathophysiology On the Web |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2], Raviteja Guddeti, M.B.B.S. [3] , Aida Javanbakht, M.D.
Overview
Pathophysiology
Systemic lupus erythematosus (SLE, or lupus) is an autoimmune disease. This means there is a problem with the body's immune system.
Normally, the immune system helps protect the body from harmful substances. But in patients with an autoimmune disease, the immune system cannot tell the difference between harmful substances and healthy ones. As a result, the immune system attacks otherwise healthy cells and tissue.
Overview
The exact pathogenesis of [disease name] is not fully understood.
OR
It is thought that [disease name] is the result of / is mediated by / is produced by / is caused by either [hypothesis 1], [hypothesis 2], or [hypothesis 3].
OR
[Pathogen name] is usually transmitted via the [transmission route] route to the human host.
OR
Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.
OR
[Disease or malignancy name] arises from [cell name]s, which are [cell type] cells that are normally involved in [function of cells].
OR
The progression to [disease name] usually involves the [molecular pathway].
OR
The pathophysiology of [disease/malignancy] depends on the histological subtype.
Pathophysiology
Pathogenesis
Immune system, genetic, and environmental factors are considered in the pathogenesis of LN.
- Immune system [1]:
- Plasma cells and B lymphocytes:
plasma cells(PC) and B cells produce autoantibodies.
B cells in LN patients have more MicroRNAs (miRNAs) which modulate gene expression [2]. Over expression of the miR-30a could lower the level of Lyn (type of protein tyrosine kinases), and lower level of Lyn may cause deposition of immune complexes in the kidney [3][4].
High number of PCs in the medulla and activation of B cells cause proteinuria and severe damage in LN.
Overexpression of apolipoprotein L1 (APOL1), a protein that induce autophagic cell death, may cause fibrosis in renal and ESRD in patients with LN [5] [6].
Low level of myotubularin-related phosphatase 3 (MTMR3), types of the phosphatidylinositol 3-phosphate that plays a role in initiating autophagy, may cause LN [7].
Macrophages play role in presenting antigens, removing of dying cells, and producing cytokines. Increase expression of Sialoadhesin (Sn), a macrophage-restricted adhesion molecule may play a role in causing sever LN [8].
- Inflammatory cytokines:
Tumor necrosis factor (TNF) is a cytokine (cell signaling protein) that play role in inflammation process. One of the sub types of TNF is TNF-like weak inducer of apoptosis (TWEAK) which has an important role in causing LN [9]. Fn14 ( TWEAK receptor) is interacted with TWEAK on renal mesangial, endothelial, tubular cells and podocytes [10]. This interactions produce multiple inflammatory mediators which lead to LN.
Increased expression of interferon alpha (IFN-α) inducible RNA transcripts by mononuclear cells.
- Repair impairment and Tissue Scarring:
Impairment in regulation and repair may cause tissue scars like [11]:
- Necrosis and extracellular matrix production cause global glomerulosclerosis [12].
- Fibrinogen leakage in to Bowman’s space cause epithelial cell hyperproliferation. Accumulation of epithelial cells make glomerular crescent. In severe LN, epithelial cells produce extra amount of matrix in Bowman’s space, which result in glomerulosclerosis [13].
- Exaggerated healing response cause hyperproliferation of mesangial and endothelial cells, and podocyte loss cause damage in renal.
- Environmental factors:
- Geographical distribution :
LN is more severe in African, Hispanics and Asian patients with SLE. LN is associated with temperature and season [14]. most flares are happening in spring and hot weather.
- Infections:
- May cause more antibodies production by B cells.
- Include:
- Ultraviolet (UV) light:
- Can stimulate B-cells to produce more antibodies
- May activate macrophages, interfere with antigen processing, and therefore increase the degree of autoimmunity.
- Diet:
Genetics
interaction and mutation between below genes from multiple categories may cause severe LN[15] [16] [17] [18].
- STAT4 [19]- TNFSF4 (OX40L) [20]- IKZF1 [21]- IRF5 [22]- TLR9 [23]- TNFAIP3 (A20) [24]- TNIP3 (ABIN3) [25]- ACE [26]- KLK [27]- FCGR2A, 3A, 3B [28]- ITGAM [29] [30] [31]- HLA DR and BLK [32].
Epigenetic modification [33]:
Hypomethylated genes in B lymphocytes activate transcription, and cause production of many anti-DNA antibodies[34].
- Histone modifications:
Histone is a protein in chromatin that play role in gene regulation.
Acetylation of histones are concidered targets for autoantibodies in LN.
- MicroRNAs:
Non-coding RNA sequences that play role in gene regulation by degradation of mRNA and protein translation blockage.
Some miRNAs are increased in LN like miR-142-3p and miR-181 and some are decreased like miR-106a, miR-17, miR-20a, miR-92a and miR-203 [35].
These changes cause dysregulation of genes and LN.
Associated Conditions
Gross Pathology
- On gross pathology: Hypertrophy and pallor of the kidney.
Microscopic Pathology
6 classification for LN on microscopy:
Class | Name | Light Microscopy | Light microscopy previews | Electron microscopy |
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I | Minimal mesangial lupus nephritis | Normal | Immune deposits in mesangial | |
II | Mesangial proliferative lupus nephritis | Mesangial widening and hypercellularity | Immune deposits in subepithelial or subendothelial | |
III | Focal lupus nephritis | Necrotizing and sclerosing lesions in < 50% glomeruli | Fibrinoid necrosis and crescents in glomeruli, Immune deposits in subendothelial space of the glomerular capillary and mesangium | |
IV | Diffuse lupus nephritis | mesangial, endocapillary and mesangiocapillary involvement > 50% | Diffuse wire loop deposits, extensive subendothelial deposits | |
V | Lupus membranous nephropathy | thickening of capillary of the glomeruli | Global or segmental subepithelial immune deposits | |
VI | Advanced sclerosing lupus nephritis | Sclerosis of the glomeruli > 90% | Global or segmental subepithelial immune deposits |
Accumulation of epithelial cells makes glomerular crescent.
Videos{{#ev:youtube|Tw07BFaDEo0}} References
References |