cytidylyl-3--5--guanosine and Lupus-Erythematosus--Systemic

Systemic lupus erythematosus (SLE) is a multifactorial disease of unknown etiology. Characteristic features of SLE include (1) polyclonal B cell activation, (2) overexpression of the immune stimulatory cytokine interleukin-6 (IL-6), (3) defective tolerance to self antigens, and (4) production of anti-DNA antibodies (Ab). Bacterial infection has been suspected as a triggering factor for lupus. Bacterial DNA differs from vertebrate DNA in the frequency and methylation of CpG dinucleotides. These CpG motifs in bacterial DNA induce a variety of immune effects, including (1) polyclonal activation of murine and human B cells, (2) IL-6 secretion, and (3) resistance to apoptosis, thereby potentially allowing the survival of autoreactive cells. These results suggest that microbial DNA could therefore be a pathogenic factor in SLE. SLE patients have elevated levels of circulating plasma DNA which is reportedly enriched in hypomethylated CpGs. Genomic DNA is also hypomethylated in SLE. The purpose of this review is to summarize the immune effects of CpG motifs and to present the evidence for their possible involvement in the pathogenesis of SLE.

Topics: Base Sequence; Dinucleoside Phosphates; DNA, Bacterial; Humans; Lupus Erythematosus, Systemic; Molecular Sequence Data

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease associated with aberrant activation of T and B lymphocytes for the production of inflammatory cytokines and autoreactive antibodies. Animal studies of SLE have indicated that Toll-like receptors (TLR) are important in the pathogenesis of murine lupus. In the present clinical study, differential protein expressions of TLR-1-9 of monocytes and different lymphocyte subsets from patients with SLE and normal control subjects were determined by flow cytometry. Results showed that the expression of intracellular TLRs (TLR-3, -8, -9) and extracellular TLRs (TLR-1, -2, -4, -5, -6) were elevated in monocytes, CD4(+) T lymphocytes, CD8(+) T lymphocytes and B lymphocytes of SLE patients compared to control subjects (all P < 0.001). Moreover, cell surface expression of TLR-4 on CD4(+) T lymphocytes and CD8(+) T lymphocytes, and TLR-6 on B lymphocytes, were correlated positively with SLE disease activity index (SLEDAI) (TLR-4 on CD4(+) T lymphocytes and CD8(+) T lymphocytes: r = 0.536, P = 0.04; r = 0.713, P = 0.003; TLR-6 in B lymphocytes: r = 0.572, P = 0.026). In concordance with the above results, there is an observable increased relative induction (%) of inflammatory cytokine interleukin (IL)-1beta, IL-6, IL-10 and IL-12, chemokines CCL2, CXCL8, CCL5 and CXCL10 from peripheral blood mononuclear cells (PBMC) upon differential stimulation by PolyIC (TLR-3 ligand), lipopolysaccharide (TLR-4 ligand), peptidoglycan (TLR-2 ligand), flagellin (TLR-5 ligand), R837 (TLR-7 ligand) and CpG DNA (TLR-9 ligand) in SLE patients compared to controls. These results suggest that the innate immune response for extracellular pathogens and self-originated DNA plays immunopathological roles via TLR activation in SLE.

Topics: Adult; Aminoquinolines; B-Lymphocytes; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Chemokines; Dinucleoside Phosphates; Female; Flagellin; Humans; Imiquimod; Immunity, Innate; Interferon Inducers; Interleukins; Leukocytes, Mononuclear; Lipopolysaccharides; Lupus Erythematosus, Systemic; Middle Aged; Monocytes; Peptidoglycan; Poly I-C; RNA; Severity of Illness Index; Toll-Like Receptors; Tumor Necrosis Factor-alpha; Young Adult