Agata Kosmaczewska

The significance of Treg cells in defective tumor immunity

Regulatory T cells (Treg) enriched in FoxP3+, glucocorticoid-induced TNF receptor+, and cytotoxic T-lymphocyte-associated antigen-4+ exert a potential to suppress effector T cells in the periphery. These cells exist in markedly higher proportions within tumor-infiltrating lymphocytes, peripheral blood lymphocytes, and/or regional lymph node lymphocytes of patients with cancer and their frequencies are suggested to be strongly related to tumor progression and inversely correlated with the efficacy of treatment. Tumor-specific Treg cells require ligand-specific activation and cell-to-cell contact to exert their suppressive activity on tumor-specific effector cells (CD8+ cytotoxic T lymphocytes and CD4+ Th cells), which includes decreased cytotoxity, proliferation, and Th1 cytokine secrection. Depletion or blockade of Treg cells can enhance immune protection from tumor-associated antigens that are expressed as self antigens. Recent studies revealed that lymphoma T cells might adopt a Treg profile as well. Studies assessing the influence of chemotherapy on Treg cells have also been included in this review.

Stimulated peripheral production of interferon-gamma is related to fatigue and depression in multiple sclerosis

OBJECTIVES The aim of the study was to evaluate the stimulated production of interferon-gamma (IFNγ) by peripheral CD3+CD4+ T lymphocytes in patients with multiple sclerosis (MS) with regard to the degree of fatigue, and to investigate relationships between immunological parameters, level of depression and clinical variables. METHODS Forty MS patients (30 women, 10 men, aged 22-60 years): 20 fatigued and 20 non-fatigued were involved in the study. Fatigue was evaluated using the Fatigue Severity Scale (FSS) and Modified Fatigue Impact Scale (MFIS), depression level - using Beck Depression Inventory (BDI). Production of IFNγ by stimulated peripheral blood CD3+CD4+ T lymphocytes, assessed using flow cytometry, was compared between MS patients with different levels of fatigue and controls. Correlations were searched out between immunological findings and BDI, age, duration and course of MS, relapse rate, disability (assessed in Expanded Disability Status Scale - EDSS) and its progression. RESULTS Stimulated production of IFNγ by CD3+CD4+ T lymphocytes was higher in severely fatigued patients in comparison with non-fatigued ones and controls, tended to correlate with FSS and MFIS, and correlated with BDI. No relationships were found between immunological findings and disease-related variables. CONCLUSION Stimulated production of IFNγ by peripheral CD3+CD4+ T lymphocytes is related to fatigue and depression in MS patients.

The CTLA-4 gene polymorphisms are associated with CTLA-4 protein expression levels in multiple sclerosis patients and with susceptibility to disease

Cytotoxic T‐lymphocyte antigen‐4 (CTLA‐4) is an important molecule in the down‐regulation of T‐cell activation. A study was undertaken to evaluate the association of the CTLA‐4 gene polymorphisms −319C/T, +49A/G, (AT)n, CT60A/G and Jo31G/T with the levels of membrane CTLA‐4 (mCTLA‐4) and cytoplasmic CTLA‐4 (cCTLA‐4) in CD4+ T lymphocytes from patients with multiple sclerosis (MS) and with susceptibility to MS, and the course of the disease. It was found that the Jo31GG and CT60GG genotypes were associated with decreased mean fluorescence intensity (MFI) of total CTLA‐4 (mCTLA‐4 + cCTLA‐4) molecules in CD4+ T cells from both relapsing‐remitting (RR) and secondary progressive (SP) MS patients compared with others. Consequently, possessing the Jo31G allele and/or the CT60G allele were associated with susceptibility to MS. The percentages of cells expressing mCTLA‐4 and cCTLA‐4 in RR patients were higher in carriers of the alleles non‐predisposing to MS (namely CT60A and Jo31T), but the percentages of corresponding cells were unexpectedly significantly lower in SP patients than in RR patients. Increased risk of paresthesia and pyramidal signs as a first manifestation of disease, and earlier transition to the SP form in those patients, was also noted. It is hypothesized that the decreasing frequencies of cells expressing immunosuppressive mCTLA‐4 and cCTLA‐4 in carriers of alleles non‐predisposing to MS (i.e. CT60A and Jo31T) may lead to inadequate down‐regulation of ongoing T‐cell responses in these patients and, as a consequence, earlier progression of disease from the RR form to the SP form.

Expression of Signal-Transducing Zeta Chain in Peripheral Blood T Cells and Natural Killer Cells in Patients with Hodgkin's Disease in Different Phases of the Disease

A number of phenotypic and functional alterations have been described in T cells of cancer patients. These changes are believed to reflect an impaired T-cell mediated immunity, which in turn, may result in a decreased capacity to generate an effective antitumor response. Several mechanisms have been proposed to explain depressed immunity in cancer patients including tumor-derived suppressor factors, abnormal cytokine production, deletion or inactivation of tumor-reactive T-cells. To investigate the mechanism underlying the immunodeficiency in Hodgkins disease (HD) we studied the expression of T cell receptor zeta chain, which plays a vital role in the cascade of events leading to T and NK cell activation. The expression of the zeta chain of the T cell receptor/CD3 complex was analyzed by dual colour immunofluorescence on peripheral blood T lymphocytes: CD3+, CD4+, CD8+ and NK-cells (CD56+) in patients in different phases of the disease. Zeta chain was significantly reduced on CD3, CD4, CD8, and CD56 positive cells from patients in active phase of the disease compared with normal controls (p=0.05). In patients tested in complete clinical remission the values were normal except for the subpopulation of CD8+ cells in which the expression of zeta chain remained significantly reduced compared with controls. Downregulation of CD3/zeta-chain in PBLs and NK cells in active phase of HD- and to a lesser extent in clinical remission may contribute to immunodeficiency associated with the disease.

Alterations in the expression of signal-transducing CD3ζ chain in T cells from patients with chronic inflammatory/autoimmune diseases

The CD3ζ chain, a component of the T cell receptor (TCR)/CD3 complex, is considered to be a limiting factor in the assembly and transport of the TCR/CD3 complex to the cell surface and is crucial to receptor signaling function. Recent studies have demonstrated altered expression and function of this signal transduction molecule in T and natural killer cells in patients with chronic inflammatory/autoimmune diseases. In this review, current knowledge concerning the expression of CD3ζ chain as well as the mechanisms responsible for abnormal expression of this molecule in systemic lupus erythematosus, rheumatoid arthritis, and childhood idiopathic nephrotic syndrome are summarized.

Dysregulated Expression of Both the Costimulatory CD28 and Inhibitory CTLA-4 Molecules in PB T Cells of Advanced Cervical Cancer Patients Suggests Systemic Immunosuppression Related to Disease Progression

Cervical cancer (CC) occurs more frequently in women who are immunosuppressed, suggesting that both local and systemic immune abnormalities may be involved in the evolution of the disease. Costimulatory CD28 and inhibitory CTLA-4 molecules expressed in T cells play a key role in the balanced immune responses. There has been demonstrated a relation between CD28, CTLA-4, and IFN genes in susceptibility to CC, suggesting their importance in CC development. Therefore, we assessed the pattern of CD28 and CTLA-4 expression in T cells from PB of CC patients with advanced CC (stages III and IV according to FIGO) compared to controls. We also examined the ability of PBMCs to secrete IFN-gamma. We found lower frequencies of freshly isolated and ex vivo stimulated CD4 + CD28+ and CD8 + CD28+ T cells in CC patients than in controls. Loss of CD28 expression was more pronounced in the CD8+ T subset. Markedly increased proportions of CTLA-4+ T cells in CC patients before and after culture compared to controls were also observed. In addition, patients’ T cells exhibited abnormal kinetics of surface CTLA-4 expression, with the peak at 24 h of stimulation, which was in contrast to corresponding normal T cells, revealing maximum CTLA-4 expression at 72 h of stimulation. Of note, markedly higher IFN-gamma concentrations were shown in supernatants of stimulated PBMCs from CC patients. Conclusions: Our report shows the dysregulated CD28 and CTLA-4 expression in PB T cells of CC patients, which may lead to impaired function of these lymphocytes and systemic immunosuppression related to disease progression.

Peripheral blood Th17/Treg imbalance in patients with low-active systemic lupus erythematosus.

INTRODUCTION The balance between proinflammatory Th17 cells and regulatory T cells plays an important role in the pathogenesis of autoimmune diseases, including systemic lupus erythematosus (SLE). In particular, an increased ratio of Th17/Treg cells has been shown to correlate with active SLE and specific organ involvement. The aim of our study was to assess Th17 and Treg cell populations in peripheral blood (PB) of patients with clinically quiescent SLE, and to evaluate their correlation with organ involvement. MATERIAL/METHODS We performed flow cytometric analysis of studied T CD4+ cell subpopulations in PB from 21 patients with SLE and 13 healthy controls. Disease activity was measured with the SELENA-SLEDAI index; organ involvement was divided into renal, neurological and hematological. RESULTS A statistically significant difference (p<0.01) between the mean percentages of CD4+CD25highFoxP3+ Treg cells in SLE patients (18.57%) and healthy controls (32.08%) was observed. Similarly, proportions of functional CTLA-4+ Treg cells were markedly lower in SLE patients than in healthy controls--19.3% vs. 23.82% (p=0.03). In contrast, SLE patients exhibited a significantly increased frequency of circulating Th17 cells with the phenotype CD4+IL-17+ compared to controls--1.36 % vs 0.19% (p<0.01). Also the ratio of Th17 cells to Th1 cells was markedly higher in SLE patients than in the control group (p<0.01). We did not find any correlation of PB Th cell distribution with organ involvement in SLE patients examined. CONCLUSIONS Our report showed for the first time that systemic Th17/Treg imbalance occurred also in patients with low disease activity and in remission. We suggest that immunological alterations may precede clinical and laboratory symptoms of the disease activity.

Different patterns of activation markers expression and CD4+ T-cell responses to ex vivo stimulation in patients with clinically quiescent multiple sclerosis (MS)

Patients with relapsing-remitting (RR) and secondary progressive (SP) forms of multiple sclerosis (MS), although in long-term clinical remission, showed different patterns of increased expressions of the activation markers: CD69, CD40L, and both membrane/surface and cytoplasmic CTLA-4 (mCTLA-4 and cCTLA-4, respectively) in freshly isolated peripheral blood (PB) CD4+ T cells compared with controls. Also observed were dysregulated responses to ex vivo stimulation in both groups of MS patients accompanied by increased IFN-gamma synthesis. Our findings may suggest that the mechanisms leading to each clinical form of the disease may be heterogeneous.

High intracellular content of cyclin‐dependent kinase inhibitor p27Kip1 in early‐ and intermediate stage B‐cell chronic lymphocytic leukemia lymphocytes predicts rapid progression of the disease

Previous studies showed that peripheral blood lymphocytes of B‐cell chronic lymphocytic leukemia (B‐CLL) displayed a high intracellular level of cell cycle inhibitory protein p27Kip1. It has been suggested that its’ high expression may confer them survival advantage and lead to unfavorable prognosis, but the prognostic significance of p27Kip1 expression for previously untreated, non‐advanced stage B‐CLL was not established. We studied a relationship between the intracellular level of p27Kip1 of lymphocytes of early‐ and intermediate stage B‐CLL patients and their spontaneous apoptosis in vitro, as well as prognostic significance of p27Kip1 in B‐CLL lymphocytes for the risk of disease progression. Intracellular p27Kip1 content of peripheral blood lymphocytes obtained from 48 previously untreated 0–II Rai stage B‐CLL patients was determined by flow cytometry. The viability and apoptosis of those lymphocytes after 72‐h culture were also assessed. During the follow‐up period (6–71 months, median 59.5), we recorded the time elapsed to the doubling of lymphocyte count, progression to a higher Rai stage and the appearance of indications for cytostatic treatment. The p27Kip1 expression was neither correlated with initial lymphocyte count, CD38 expression, cell viability nor spontaneous apoptosis ratio after 72‐h culture. Higher p27Kip1 level was related to the probability of earlier occurrence of each of three above‐mentioned events. We did not find a prognostic significance of in vitro cell viability nor apoptosis as to the risk of disease progression. Our results indicate that elevated intracellular p27Kip1 level in leukemic lymphocytes of early‐ and intermediate stage B‐CLL patients contributes to rapid progression of the disease.

Rola subpopulacji limfocytów pomocniczych Th1, Th17 i Treg w patogenezie reumatoidalnego zapalenia stawów z uwzględnieniem przeciwzapalnego działania cytokin Th1

Dysregulation in the immune system plays an important role in the pathogenesis of rheumatoid arthritis (RA). The persistent nature of arthritis strengthens the suggestion of immune dysfunction, consisting in predominance of the pro-inflammatory response. It seems that both local and systemic immune abnormalities, including PBMC secreting abnormal levels of pro- and anti-inflammatory cytokines, may be involved in the evolution of the disease. Helper T cells (Th) differentiate towards Th1, Th2, Th17, and Treg cells according to the cytokine microenvironment. Active RA results from the imbalance in distribution of functional pro-inflammatory Th17 and anti-inflammatory Treg cells. Affected Th1 cytokine secretion observed in the course of RA contributes to the increase in IL-17 production and Th17 infiltration in the synovial tissue. Current studies have demonstrated that pro-inflammatory Th1 cytokines may also exert an anti-inflammatory action on the balance between Th17 and Treg cells by promotion of Treg differentiation. In the paper, we also show the influence of TNF-alpha and its inhibitors on the distribution of Th subpopulations in RA patients.