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T regulatory cells are involved in the peripheral tolerance mechanisms. From many years, the research has been going on to substantiate the involvement of T regulatory cells in systemic lupus erythematosus (SLE) in humans. The important subsets of T regulatory cells are CD4+ and CD25+ T cells that act as the suppressor T cells in the which, it inhibits the "activation and effector function of autoreactive T cells". Skaguchi et al first studied the deficiency of CD4+ and CD25+ subsets in the T-cells and the outcome of the test was the development of autoimmune diseases (T-cell mediated). The inadequate supply of CD4+ and CD25+ T cells to the organs can lead to the development of multiple autoimmune diseases. Along with the CD4+ and CD25+ molecules the expression of the FoxP3 in the intracellular cells are important as they help in regulating the T cells and inhibiting the chances of developing the autoimmunity in humans. CD45Ro+ is the other activating marker that can help in indicating the role of T regular cells in SLE. SLE is autoimmune disease that also links with the multiple defects in the person suffering from this disease. From the previous studies, it has been hypothesized that the defect in the T regulatory cells leads to the pathogenesis of the SLE. The various markers of T regulatory cells can be tested which, can lend a hand in knowing the defects in the T regulatory cells in SLE or the tolerance mechanisms in the SLE.
Materials and Methods:
For the material in the test, we can study the group of patients with SLE in an active and inactive state along with the group of the healthy controls to compare the results between them. The peripheral blood molecular cells (PBMC) are used to test the level of CD4+ and CD25+ T cells. The cell separation (High gradient magnetic sorting) method and flow cytometry can be valuable for the separation of CD4+ CD25- and CD4+ CD25+. Other methods such as Real time PCR or using assay method or cytokine detection can be lend a good hand in knowing the role of T regulatory cells in SLE.
To determine that the T regulatory cells are involved in SLE in human we need to contrast the occurrence of CD4+ CD25+, CD4+CD25+CD45+ and FoxP3 protein. We can also correlate the results with the other diseases or production of autoantibodies. If the T regulatory cells are involved in the development of SLE in humans then the levels of CD4+CD25+ should show significant difference between the SLE patient and the healthy control. If the experiment is carried out to test the involvement of T regulatory cells in SLE then the following results should be expected for the confirmation its involvement.
From the expected results of the CD4+CD25+ Treg, level in SLE patient should be lower then the healthy control. The CD69 (early activation marker) and CD71 (late activation marker) were also measured as for the comparison with the SLE patients and healthy controls. From the above figure 1, the level of CD4+CD25+ Treg in the active SLE is lower when compared to the SLE inactive and healthy controls. The comparison of CD4+CD25+ Treg and CD4+CD25+CD45Ro+ T cells in SLE and HC. To make a distinction in the T cells the FOXP3+ expression is the most important marker. At some point, it is hard to differentiate the levels of FOXP3+ in CD4+ from the SLE and HC. However, the level of CD25+ cells in the SLE patients (CD4+FoxP3+) is higher when compared with the healthy controls. From the study, it can be hypothesized that the failing in conversion from FoxP3+CD25- to FoxP3+CD25+ leads to the reduction in the CD4+ CD25+ T cells in SLE patients. The above statement could be factual as the level FoxP3+CD25- cells in SLA patients were higher. The
CD4+CD25+ T reg level measured in SLE patients shows decreased levels in comparison with HC and inactive SLE patients. Similarly, the FoxP3 protein levels in the CD4+CD25high are higher in the healthy control, while the SLE patients show lower level of FoxP3 protein level.
Other important factors that can contribute more light on T regulatory cells involved in development of SLE are the TNF, IL-12 and IL-2. Valencia. en al conducted a series of experiment which reveal that the impairment in the T regulatory cells in SLE patients. The reason that leads to the impairment of T regulatory cells is TNFRII. In the CD4+CD25+ subset the factor TNFRII levels are higher (That is the level of TNF in the SLE patient is higher and the level of CD4+CD25high is lower). This could be due to the over production of TNFRII in SLE patient. Similarly, IL-2 also contributes in suppression of CD4+CD25+ T cells by intervene with cell-cell contact.
The specificity and the pathogenesis of T regulatory cells remains a mystery as the mechanisms of tissue injury that arises in the SLE patients is still unclear. Although the test results shows the defect in T regulatory cells in SLE patients, the above test results could not be counted as the confirmatory test. Several reasons that encounter the criteria that leads difficultly in confirmation of teat results. For example, the CD25 molecule is a discomfited marker because not all the CD4 + CD25+ T cells are T regulatory cells, it is difficult to differentiate between CD25+ from CD25- T cells in humans, and even their findings do not present the suppressive activity. In humans, the located portion of CD25+ in the CD4+CD25+ T cells has the high density and helps in functioning of T regulatory cells. Due to this reason, it is required to verify an imperfection in the CD4+CD25high T regulatory cells in SLE patients. Other possibility that might help to clear the role of T regulatory cells in SLE is the use of corticosteroids or other drugs. For example, if the level of CD4+CD25+ T cells/ FoxP3 increases by treating with corticosteroids to SLE patients. However, the potential of treating SLE patients therapeutically using T regulatory cells hold a great challenge in future.