systemic lupus erythematosus (SLE)

Last edited 08/2021 and last reviewed 08/2021

Systemic lupus erythematosus is the classic prototype of a chronic, multisystem, inflammatory connective tissue disorder of autoimmune origin (1,2).

often follows a relapsing and remitting pattern (3)
the disease is characterised by the presence of a wide spectrum of autoantibodies (2)

98% of SLE patients have antinuclear antibodies (ANA) but are non-specific
anti-double-stranded DNA (dsDNA) seen in around 70% of cases is highly specific for SLE
other autoantibodies present in SLE patients include - anti-Smith, anti-ribosomal P and anti-proliferating cell nuclear antigen (PCNA) (3)

it is non-organ specific and characterised by vasculitis
due to its broad clinical presentation the disease may vary from rash and arthritis through anaemia and thrombocytopenia to serositis, nephritis, seizures, and psychosis (4)
SLE, as a chronic inflammatory disorder, is thought to be driven by autoantibodies that target multiple organ systems including joints, skin, and kidneys
- SLE is characterized by pathogenic autoantibodies that target specific tissues, however many additional cell types (for example B cells, T cells) and cytokines (for example type I interferon (IFN-I)-a) are involved in the inflammatory response (5)
- dysregulation of both adaptive and innate immunity plays a role in the pathogenesis of SLE
  - adaptive immunity and SLE
    - B cells play a central role in the pathogenesis of SLE, mainly by producing autoantibodies but also by producing cytokines and by presenting antigens to T cells
    - SLE can occur secondary to defective proteins that regulate T cells in the dysfunctional clearance of immune cells
      - thus part of the pathology of SLE may be due to loss of the immune tolerance and the persistence of attractive B- and T-cell populations
  - inate immunity and SLE
    - dysregulation of the innate immune system also contributes to SLE
    - immune complexes of autoantibodies with endogenous RNA and DNA can be taken up by plasmacytoid dendritic cells
      - leads to activation of toll-like receptor (TLR)7 and TLR9, respectively, and generates IFN-I
        
        IFN-I can lead to further augmentation of adaptive immunity by enhancing the antigen-presenting function of monocytes and dendritic cells and activating B cells

Clinical variants of lupus erythematosus

Some of the clinical variants of lupus erythematous include the following (6):

systemic lupus erythematosus (SLE)
cutaneous lupus erythematosus (CLE) (including subacute cutaneous lupus erythematosus (SCLE) and discoid lupus erythematosus (DLE))
child-onset lupus erythematosus
neonatal lupus erythematosus
drug-induced lupus erythematosus (DILE)

Reference: