Stage Dependent Aberrant Regulation of Cytokine-STAT Signaling in Murine Systemic Lupus Erythematosus

Abstract

Systemic lupus erythematosus (SLE) is a complex autoimmune disease of unknown etiology that involves multiple interacting cell types driven by numerous cytokines and autoimmune epitopes. Although the initiating events leading to SLE pathology are not understood, there is a growing realization that dysregulated cytokine action on immune cells plays an important role in promoting the inflammatory autoimmune state. We applied phospho-specific flow cytometry to characterize the extent to which regulation of cytokine signal transduction through the STAT family of transcription factors is disturbed during the progression of SLE. Using a panel of 10 cytokines thought to have causal roles in the disease, we measured signaling responses at the single-cell level in five immune cell types from the MRLlpr murine model. This generated a highly multiplexed view of how cytokine stimuli are processed by intracellular signaling networks in adaptive and innate immune cells during different stages of SLE pathogenesis. We report that robust changes in cytokine signal transduction occur during the progression of SLE in multiple immune cell subtypes including increased T cell responsiveness to IL-10 and ablation of Stat1 responses to IFNα, IFNγ, IL-6, and IL-21, Stat3 responses to IL-6, Stat5 responses to IL-15, and Stat6 responses to IL-4. We found increased intracellular expression of Suppressor of Cytokine Signaling 1 protein correlated with negative regulation of Stat1 responses to inflammatory cytokines. The results provide evidence of negative feedback regulation opposing inflammatory cytokines that have self-sustaining activities and suggest a cytokine-driven oscillator circuit may drive the periodic disease activity observed in many SLE patients.

Stat3 promotes IL-10 expression in lupus T cells through trans- activation and chromatin remodeling

“…Conflicting data exist regarding Stat5 in SLE (21,22). Although attenuated IL-2 expression in SLE T cells suggests reduced Stat5 activation (23)(24)(25), one study demonstrated increased Stat5 phosphorylation in SLE (22).…”

New technologies for autoimmune disease monitoring

“…Another study has demonstrated the ability to use correlational data obtained by phospho-specific flow cytometry to build directional, statistical maps of phospho-signaling networks within primary cells [8]. Although not yet utilized in any studies of T1D, the technique has been utilized in studies of an animal model of systemic lupus erythematosus (SLE) [9 • ]. SLE is a complex autoimmune disease of unknown cause that involves multiple interacting cell types driven by numerous cytokines and autoantigens.…”

“…Investigators in Dr Nolan’s laboratory applied phospho-specific flow cytometry to characterize the extent to which regulation of cytokine signal transduction through the STAT family of transcription factors was disturbed during the progression of SLE. Using a panel of 10 cytokines thought to have causal roles in the disease, they measured signaling responses at the singlecell level in five immune cell types from the MRLlpr mice [9 • ]. Their results suggested that negative feedback regulation opposed inflammatory cytokines that have self-sustaining activities, and suggested to them that a cytokine-driven oscillator circuit may drive the periodic disease activity observed in many SLE patients.…”

“…Because the cells are perturbed from their resting state, induced phenotypes corresponding to higher or lower levels of cytokine induction can be read. These may be more sensitive biomarkers of diseases such as autoimmunity, where resting levels of cytokines in blood are still mostly undetectable, but where dysregulation of cell signaling pathways may be visualized as changes in the induced state [9 • ]. The information thus gleaned is not as precise as that from, say, intracellular cytokine staining, where the production of cytokines is analyzed on a per-cell basis for each cell subset being interrogated.…”

“…It can also potentially be useful to track mitogen responses as well as antigen-specific T-cell responses because dysregulation of signaling networks in autoimmunity can extend beyond the self-reactive T cells [9 • ]. CD3 + CD28 stimulation, or an activating combination of CD2 antibodies, is potentially appropriate, physiologically relevant stimuli to use in this regard.…”