T lymphocyte subset imbalances in patients contribute to ankylosing spondylitis

Abstract

Ankylosing spondylitis is a chronic inflammatory rheumatic disease, which is characterized by inflammation of the spine and the sacroiliac joints. To date, the disease etiology remains unclear. In the present study, the correlation of T lymphocyte subset changes with the progression of ankylosing spondylitis was investigated. A total of 55 patients with ankylosing spondylitis (22 severe and 23 mild cases) and 20 healthy individuals were selected. Firstly, the punctured cells in the lesions and the serum were collected, and the lymphocytes and the peripheral blood mononuclear cells were prepared. Secondly, quantitative PCR, ELISA and flow cytometry analyses were carried out to detect the levels of a series of immunoglobulins, complements, helper T cells, cytotoxic T cells, regulatory cells and cytokines. The expression levels of α-globulin, γ-globulin, immunoglobulin (Ig)G, IgA, IgM, serum complement C3, and complement C4 were found to be significantly increased in ankylosing spondylitis patients. In addition, the percentage of Th1 and Th17 cells was found to be significantly higher in the ankylosing spondylitis groups (mild and severe) compared with the healthy individuals. As a result, the Th1/Th2 and Th17/Treg ratios were significantly higher in patients with ankylosing spondylitis. In addition, T lymphocyte subset ratio imbalances contributed to an increased expression of immune mediators, including interferon (IFN)-γ and interleukin (IL)-17A. The mRNA and protein expression levels of IFN-γ and IL-17A were found to be higher in the ankylosing spondylitis groups compared with the control group. The present study provided further evidence on the function and underlying mechanism of T lymphocyte subsets, which may be useful in the diagnosis and treatment of ankylosing spondylitis.

Keywords: T lymphocyte subsets; ankylosing spondylitis; cytokines; imbalance; inflammation.

Figure 1

Changes in (A) the percentage of CD3⁺, CD3⁺CD8⁻ and CD3⁺CD8⁺ cells and (B) the CD3⁺CD8⁻/CD3⁺CD8⁺ ratio among the control, mild ankylosing spondylitis and severe ankylosing spondylitis groups.

Figure 2

Th1/Th2 and Tc1/Tc2 ratio imbalance in patients with ankylosing spondylitis. The percentages of (A) Th1 and (B) Th2 cells, (C) Th1/Th2 ratio, percentages of (D) Tc1 and (E) Tc2 cells and (F) Tc1/Tc2 ratio are shown for the control, mild ankylosing spondylitis and severe ankylosing spondylitis groups. Different letters indicate a significant difference among the groups (P<0.05). Th, T helper; Tc, T cytotoxic.

Figure 3

Percentages of (A) Tc17, (B) Th17 and (C) Treg cells, as well as (D) the Th17/Treg ratio, are shown for the control, mild ankylosing spondylitis and severe ankylosing spondylitis groups. Different letters indicate a significant difference among the groups (P<0.05). Tc, T cytotoxic; Th, T helper; Treg, regulatory T.

Figure 4

Relative mRNA and protein expression levels of (A) IFN-γ, (B) IL-17A, (C) IL-4 and (D) TGF-β are shown for the control, mild ankylosing spondylitis and severe ankylosing spondylitis groups. Different letters indicate a significant difference among the groups (P<0.05). IFN, interferon; IL, interleukin; TGF, tumor growth factor.