Therapeutic potential of targeting Tfr/Tfh cell balance by low-dose-IL-2 in active SLE: a post hoc analysis from a double-blind RCT study

Abstract

Objective: To investigate the regulation of T follicular regulatory (Tfr) and T follicular (Tfh) cell subtypes by low-dose IL-2 in systemic lupus erythematosus (SLE) in a randomized, double-blind, placebo-controlled clinical trial.

Methods: A post hoc analysis was performed in a randomized cohort of SLE patients (n=60) receiving low-dose IL-2 therapy (n=30) or placebo (n=30), along with the standard of care treatment. The primary endpoint was the attainment of SLE responder index-4 (SRI-4) at week 12 in the trial. Twenty-three healthy controls were enrolled for T cell subset detection at the same time as the trial. The t-stochastic neighbor embedding (tSNE) analysis of CD4 T subsets based on immune cells flow cytometry markers was performed to distinguish Tfh, Tfh1, Tfh2, Tfh17, and Tfr cell subsets.

Results: Compared with HC, the frequency of Tfr (CXCR5+PD-1low Treg and CXCR5+PD-1high Treg) cells was significantly reduced, while the pro-inflammatory Tfh cells were increased in patients with SLE. The imbalanced Tfh cell was associated with several pathogenic factors (anti-dsDNA antibodies (r=0.309, P=0.027) and serum IL-17 (r=0.328, P=0.021)) and SLE Disease Activity Index (SLEDAI) score (r=0.273, P=0.052). Decreased CXCR5+PD-1low Treg/Tfh and CXCR5+PD-1low Treg/Tfh17 were both associated with increased immunoglobulin M (IgM) (r=-0.448, P=0.002 and r=-0.336, P=0.024, respectively). Efficacy of low-dose IL-2 therapy was associated with a restored Tfr/Tfh cell balance.

Conclusion: These data support the hypothesis that promotion of Tfr is associated with decreased disease activities and that low-dose IL-2 therapy can recover Tfr/Tfh immune balance.

Trial registration number: ClinicalTrials.gov Registries ( NCT02465580 ).

Keywords: Low-dose interleukin-2; Systemic lupus erythematosus; T follicular helper cell; T follicular regulatory cell.

Conflict of interest statement

The authors declare that they have no competing of interests.

Figures

Fig. 1

tSNE analysis of CD4 T subsets based on immune cells flow cytometry markers. tSNE, t-stochastic neighbor embedding

Fig. 2

The correlations between CD4 T cell subsets and clinical characters in SLE. SLEDAI, SLE Disease Activity Index. ESR, erythrocyte sedimentation rate. C3, complement 3. C4, complement 4. IFN-α, interferon-α. IL-2, Interleukin-2. IL-21, interleukin-21. IL-7, interleukin-7. IFN-γ, interferon-γ. IL-17, interleukin-17. IL-10, interleukin-10. TGF-β, tumor necrosis factor-β. The scale color of the filled squares indicates the strength of the correlation (r) and whether it is negative (blue) or positive (red). **, P

Fig. 3

The correlations between CD4 T cell subsets and B cells and immunoglobulins in SLE. B, B cell. Plasma B, plasma B cell. Switched B, switched memory B cells. IgA, immunoglobulin A. IgG, immunoglobulin G. IgM, immunoglobulin M. AnuA, anti-nucleosome antibodies. dsDNA, anti-double stranded DNA antibodies. The scale color of the filled squares indicates the strength of the correlation (r) and whether it is negative (blue) or positive (red). *, P

Fig. 4

The response of clinical and immune cells to low-dose IL-2 (n=30) and placebo (n=30) therapy in SLE. A Relative change of disease activity value and patient number. B Relative change of ratios at baseline and week 12. C Relative change of Treg subsets at baseline and week 12. D Relative change of Tfh subsets at baseline and week 12. BILAG, British Isles Lupus Assessment Group. SLEDAI, Safety of Estrogens in Lupus Erythematosus National Assessment version of the SLE Disease Activity Index. SRI-4, SLE Responder Index-4. PGA, physician’s global assessment. All data here were normalized to baseline values to show relative changes. In detail, all baseline data and data after therapy were divided by the value of baseline. #, absolute number, cells/μl. %, proportion of cells in lymphocyte