Additionally, IL-21 levels were significantly increased in samples from patients with Systemic Lupus Erythematosus (mean+/- SD: n = 14, 202.64 +/- 111.47 fg/mL, p = .0001 for Quanterix SiMoA and 275.4 +/- 174.66 fg/mL p = .0001 for MSD S-PLEX®) as well as in samples from patients with Sjögren's Syndrome (mean+/- SD: n = 11, 122.18 +/- 84.50 fg/mL, p = .0029 for Quanterix SiMoA and 183.64 +/- 153.00 fg/mL, p = .0082 for MSD S-PLEX®) when compared to healthy donors (mean+/- SD: n = 11, 38.1 +/- 27.8 fg/mL for Quanterix SiMoA and 58.1 +/- 30.7 fg/mL for MSD S-PLEX®).
Altogether, our results indicate that β2-Glycoprotein I is able to elicit a local Interleukin-17/Interleukin-21 and Interferon-γ inflammation in lupus-antiphospholipid syndrome patients that might lead, if unabated, to plaque instability and subsequent arterial thrombosis, suggesting that the T helper 17/T helper 1 pathway may represent a novel target for the prevention and treatment of the disease.
We aimed to determine whether single nucleotide polymorphisms (SNP) near the IL-21 gene have significant association with SLE susceptibility and the T helper-related inflammatory cytokine profile of SLE patients.
Anti-IL-21 treatment also led to a reduction in GC B cells, CD138<sup>hi</sup> plasmablasts, IFN-γ-dependent IgG2c production, and autoantibodies, indicating that Tfh cell-derived IL-21 is critical for pathological B cell cues in lupus.
Here, we evaluated ROCK activity in a new SLE cohort, and an RA cohort, and assessed the ability of distinct inhibitors of the ROCK pathway to suppress production of IL-17 and IL-21 by SLE T cells or human Th17 cells.
Given the inconsistent results from these studies, the present meta-analysis aimed to obtain a more precise estimate of the association between IL-21rs907715 and rs2221903 polymorphisms and SLE.
Moreover, genotypes carrying the IL-21rs2055979 A variant allele were associated with increased IL-21 levels compared to the homozygous wild-type genotype in patients with SLE.
T cells contribute to lupus pathogenesis by secreting pro-inflammatory cytokines such as IL-17, and by interacting with B cells and secreting helper factors such as IL-21 that promote production of IgG autoantibodies.
However, genetic deficiency of IL-21 associates with inflammatory bowel diseases and blockade of IL-21 in the early phases exacerbates the disease progression in some models of rheumatoid arthritis and systemic lupus erythematosus, thus suggesting a dual role of IL-21 in the control of immune-mediated diseases.
Active SLE patients had 4-fold higher IL-21 mRNA and increased levels of intracellular IL-21 in peripheral blood CD4+ T cells (mean±SD fluorescence intensity, 1.7±0.1 in active versus 0.9±0.3 in inactive SLE and controls, p=0.035).
Our results show for a first time that IL2-IL21 region seems to play a role in the response to rituximab in SLE patients but not in other autoimmune diseases.
In conclusion, our findings suggest that a SNP (rs2221903) and CC haplotype (rs2221903 and rs907715) of the IL-21 gene is associated with SLE in the Chinese population.