Lymphocyte phenotypes in systemic sclerosis

Could Lymphocyte Profiling be Useful to Diagnose Systemic Autoimmune Diseases?

Considering the implications of B, T, and natural killer (NK) cells in the pathophysiology of systemic autoimmune diseases, the assessment of their distribution in the blood could be helpful for physicians in the complex process of determining a precise diagnosis. In primary Sjögren's syndrome, transitional and active naive B cells are increased and memory B cells are decreased compared to healthy controls and other systemic diseases. However, their utility to improve the accuracy of classification criteria has not been proven. In early untreated rheumatoid arthritis, proportions of regulatory T cells are constantly reduced, but other patterns are difficult to determine given the heterogeneity of published studies. In systemic lupus erythematosus, the lack of studies using large cohorts of patients and the diversity of the possible pathological mechanisms involved are also important impediments. Nevertheless, transitional B cell and plasma cell proportions are increased in most of the studies, the CD4/CD8 ratio is decreased, and the number of NK cells is reduced. Despite the low number of studies, anomalies of lymphocyte subset distribution was also described in ANCA-associated vasculitis, systemic scleroderma, and myositis. For now, flow cytometric analysis of lymphocyte subsets has focused mainly on specific subpopulations and is more useful for basic and translational research than for diagnostics in clinical practice. However, new modern methods such as mass cytometry and bioinformatics analyses may offer the possibility to simultaneously account for the relative proportions of multiple lymphocyte subsets and define a global profile in homogeneous groups of patients. The years to come will certainly incorporate such global lymphocyte profiling in reclassification of systemic autoimmune diseases.

T and NK Cell Phenotypic Abnormalities in Systemic Sclerosis: a Cohort Study and a Comprehensive Literature Review

Scleroderma (SSc) is a rare and heterogeneous immune-mediated disease involving the connective tissue and microvasculature whose pathogenesis remains unclear. Data concerning T and natural killer (NK) cell abnormalities and cytokine levels in the peripheral blood (PB) from patients with SSc are scarce, and the results are contradictory. The present study aimed to analyze the changes of T lymphocytes, NK cells, and T helper (Th)-related cytokines in the PB of patients with SSc in comparison to healthy individuals and its relation to disease subtype and stage, organ involvement, and nailfold capillaroscopic changes. A non-random convenience sample of 57 scleroderma patients was utilized. Fifty-five out of the 57 patients studied were women (97 %); 10 patients presented pre-scleroderma (pre-SSc) and 47 SSc: 34 limited cutaneous SSc (lcSSc) and 13 diffuse cutaneous SSc (dcSSc). Patients with SSc were classified in early (n = 7), intermediate (n = 10), and late (n = 30) disease. Blood samples were analyzed by flow cytometry for total T cells, CD4+ and CD8+ T cell subsets, total NK cells, and CD56+low and CD56+high NK cell subsets. T cells were further analyzed for the expression of the CD56 adhesion molecule and activation-related markers (HLA-DR, CD45RO). In addition, the serum levels of Th1-, Th2-, and Th17-related cytokines were measured by flow cytometry. Twenty-five healthy individuals recruited from the blood bank were used as controls. Patients had lower numbers of total lymphocytes and T cells comparing to healthy controls. Both CD4+ and CD8+ T cells were decreased, but differences were statistically significant only for CD8+ and CD8+ CD45RO+ T cells. These alterations were seen in patients with SSc but not in patients with pre-SSc, and, in general, they were more pronounced in patients with dcSSc than in patients with lcSSc, in patients with vascular involvement than in those without, as well as in patients having active and late nailfold capillaroscopic patterns. CD56+ T cells were also decreased in SSc patients, especially in those with active/late capillaroscopic patterns or with severe lung disease. Diminished numbers of circulating NK cells were also observed in patients with lcSSc and in those with early disease. No statistically significant changes were found in serum cytokine levels, as compared with controls. Patients with SSc had major alterations in circulating CD8+ and CD56+ T cells, as well as in NK cells, suggesting that these cells may play a relevant role in SSc pathogenesis, probably operating at different phases and/or at different organs. In addition, the serum levels of Th1, Th2, and Th17 cytokines did not provide useful information for evaluating T cell polarization in SSc.

Response of T-cell subpopulations to superantigen and recall antigen stimulation in systemic sclerosis

Background:

There is great disagreement regarding which effector T-cells are responsible for the pathogenesis of systemic sclerosis. Further, the possible role of superantigens in modulating the T-cell phenotype responsible for the immunopathogenesis of this disease and the response of these patients to common recall antigens have not been adequately determined.

Aims:

To investigate the T-cell subsets and activation markers in peripheral blood mononuclear cells of systemic sclerosis patients before and after stimulation with different bacterial superantigens and common recall antigens to better understand the immunopathogenesis of this disease.

Materials and Methods:

T-cells (CD3⁺) from 20 systemic sclerosis patients and 17 age-matched healthy controls were studied using flow cytometry for the expression of CD4, CD8, CD45RA, and CD45RO at baseline and upon stimulation with different superantigens and recall antigens. Patients were also tested for skin delayed hypersensitivity to common recall antigens.

Results:

The proportions of CD45RA⁺ (naive) and CD45RO⁺ (memory) CD4⁺ T-cells were found to be significantly higher in patients than in controls upon stimulation with bacterial superantigens. However, T-cells from these patients responded weakly to recall antigen stimulation, indicating a loss of specific memory cells. This was further supported by the skin delayed hypersensitivity test in which 16 patients were found to be anergic.

Conclusions:

Our findings suggest that both naïve (CD45RA⁺) and memory (CD45RO⁺) CD4⁺ superantigen-reactive T-cells are effector T-cells that may modulate the pathogenic autoantibody response in systemic sclerosis. Accumulation of these cells in these patients may result in increased risk of relapses and resistance to therapy.

Absolute count of T and B lymphocyte subsets is decreased in systemic sclerosis

Background

Previous reports on lymphocyte subpopulations in systemic sclerosis (SSc) are conflicting. Therefore, we aimed to investigate the lymphocyte subsets in SSc patients who were not on immunosuppressive therapy.

Methods

Lymphocyte subsets were assessed in the peripheral blood of SSc patients (n = 29) and healthy controls (n = 29) using the four colour flow cytometry method. Correlation studies were also performed in order to assess the relationship between lymphocyte subsets and clinical parameters.

Results

The absolute count of lymphocytes (P = 0.0042), CD3+ (P = 0.0014), CD4+ (P = 0.0070), CD8+ (P = 0.021), and CD19+ cells (P = 0.024) was significantly decreased in SSc patients when compared to healthy controls. CD4+/CD8+ ratio and the absolute count of CD56+ cells observed in SSc patients did not significantly differ from controls (P = 0.165; P = 0.632, respectively). There was no substantial relationship between the lymphocyte subset levels and clinical features (i.e., SSc subtype, autoantibody profiles, organ involvement), except for a significant inverse correlation of CD19+ cells and the modified Rodnan skin score (r = -0.43, P = 0.020).

Conclusion

Our data support previous reports indicating that subsets of T lymphocytes as well as B lymphocytes play a role in the pathogenesis of SSc.