Quantitative polymerase chain reaction analysis reveals marked overexpression of interleukin-1β, interleukin-10 and interferon-γ mRNA in the lymph nodes of lupus-prone mice

Abstract

The nature of the stimuli driving autoantibody production in systemic lupus erythematosus (SLE) is unclear, but cytokines are believed to play an important role. Since cytokines primarily appear to act locally at the tissue level, we analysed mRNA expression of several cytokines (IL-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IFNγ, TNFα, TNFβ and TGFβ1) in the lymph nodes of lupus-prone mice, in models of early onset disease. We constructed a multispecific competitor fragment that allowed quantification of these cytokine transcripts by competitive PCR assay. The results reveal considerable overexpression of IL-1β, IL-10 and IFNγ transcripts in SLE-prone MRL- lpr lpr ( MRL l ) and BXSB male (BXSBm) mice, but with some strain differences. IFNγ was most markedly augmented in MRL l mice (in some cases over 100-fold greater than control mice), IL-1β was most severely overexpressed in BXSBm mice while IL-10 was equally increased in both strains. In addition, TGFβ1 expression was moderately elevated in the lymph nodes of BXSBm (but not MRL l ) mice. We found no abnormality in the expression of the other cytokines. Cytokine transcript levels were only slightly altered at 4 weeks of age, but were elevated from 10 to 22 weeks of age. The latter phase corresponds to a period where lupus-like disease escalates, resulting in frequent mortality. Interestingly, our results do not reveal a clear Th1 or Th2 cytokine expression pattern in these lupus-prone mice. IL-1β, IFNγ and IL-10 are pleiotropic cytokines with pro-inflammatory and B-cell stimulatory effects. These results point to certain cytokines as potential targets for immunotherapy in lupus.