Increased perforin expression in multiple sclerosis patients during exacerbation of disease in peripheral blood lymphocytes

Modulation of Suppressive Activity and Proliferation of Human Regulatory T Cells by Splice-Switching Oligonucleotides Targeting FoxP3 Pre-mRNA

The maturation, development, and function of regulatory T cells (Tregs) are under the control of the crucial transcription factor Forkhead Box Protein 3 (FoxP3). Through alternative splicing, the human FoxP3 gene produces four different splice variants: a full-length variant (FL) and truncated variants with deletions of each of exons 2 (∆2 variant) or 7 (∆7 variant) or a deletion of both exons (∆2∆7 variant). Their involvement in the biology of Tregs as well as their association with autoimmune diseases remains to be clarified. The aim of this work was to induce a single FoxP3 splice variant in human Tregs by splice switching oligonucleotides and to monitor their phenotype and proliferative and suppressive activity. We demonstrated that Tregs from peripheral blood from patients with multiple sclerosis preferentially expressed truncated splice variants, while the FL variant was the major variant in healthy donors. Tregs with induced expression of truncated FoxP3 splice variants demonstrated lower suppressive activity than those expressing FL variants. Reduced suppression was associated with the decreased expression of Treg-associated suppressive surface molecules and the production of cytokines. The deletion of exons 2 and/or 7 also reduced the cell proliferation rate. The results of this study show an association between FoxP3 splice variants and Treg function and proliferation. The modulation of Treg suppressive activity by the induction of the FoxP3 FL variant can become a promising strategy for regenerative immunotherapy.

Axonal damage in multiple sclerosis

Multiple sclerosis is a debilitating disease of the central nervous system that has been characteristically classified as an immune-mediated destruction of myelin, the protective coating on nerve fibers. Although the mechanisms responsible for the immune attack to central nervous system myelin have been the subject of intense investigation, more recent studies have focused on the neurodegenerative component, which is cause of clinical disability in young adults and appears to be only partially controlled by immunomodulatory therapies. Here, we review distinct, but not mutually exclusive, mechanisms of pathogenesis of axonal damage in multiple sclerosis patients that are either consequent to long-term demyelination or independent from it. We propose that the complexity of axonal degeneration and the heterogeneity of the underlying pathogenetic mechanisms should be taken into consideration for the design of targeted therapeutic intervention.

The pathology of multiple sclerosis is the result of focal inflammatory demyelination with axonal damage

Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system manifested morphologically by inflammation, demyelination, axonal loss and gliosis. The inflammatory lesions are characterized by massive infiltration by a heterogeneous population of cellular and soluble mediators of the immune system, including T cells, B cells, macrophages and mi croglia, as well as a broad range of cytokines, chemokines, antibodies, complement and other toxic substances. The appearance of such lesions is associated with clinical relapses. Recent detailed immunopathological studies of early, acute lesions revealed profound heterogeneity in the patterns of demyelination and the factors of the immune system involved. During remission, resolution of inflammation is the main factor which leads to clinical improvement of patients. However, the immune system can play a beneficial role at this stage, promoting remyelination perhaps by production of growth factors such as BDNF. In contrast, the progressive irreversible neurological deficit in multiple sclerosis is associated with neurodegenerative processes resulting in axonal and neuronal loss. The mechanisms behind damage to axons in multiple sclerosis lesions are poorly understood. However, the close proximity of areas with prominent axonal loss and areas containing inflammatory infiltrates (e. g., T cells, macrophages) suggest that axonal damage is closely associated with inflammation. Different soluble or cellular mediators of the immune response have been shown to damage axons in experimental systems, and these may be responsible for neurodegeneration in human disease.

Inflammatory process of CD8+ CD28- T cells in induced sputum from asthmatic patients

Previously unreported CD8⁺CD28⁻ and CD8⁺CD28⁺ T-cell subsets occur in healthy individuals and expand in patients suffering from autoimmune disease. Here we studied, for the first time, the expression of CD8⁺CD28⁺, CD8⁺CD28⁻, and CD8⁺CD56⁺ subpopulations in induced sputum from asthmatics. Using sputum samples, purified CD8⁺ T cells were stained for surface antigen CD28, CD56, FITC-conjugated anti-perforin, and anti-IFN-γ. Cytotoxic activity was evaluated in a chromium releasing test. Induced sputum CD8⁺CD28⁻ T cells were found to be more expanded and expressed low levels of IFN-γ in severe asthmatics than mild asthma and age-matched healthy controls. The predominance of CD8⁺CD28⁻ T cells can be in part explained by the expansion of CD8⁺CD56⁺. CD8⁺CD28⁻ T cells from severe asthmatics produced high intracytoplasmic perforin and exerted a potent cytotoxic activity. Considering their phenotyping and functional properties, the CD8⁺CD28⁻ T-cell subset may constitute an intermediate phenotype in the process of CD8⁺ T-cell differentiation of effector-type cells in severe asthmatics. Functional studies showed that CD8⁺CD28⁻ T cells had cytotoxic function.

Tc1/Tc2 ratio in the inflammatory process in patients with Behçet's disease

BACKGROUND: Peripheral blood CD8+ T cells expressing interferon gamma and interleukin-4 (IL-4), and lacking CD28 molecules, were responsible for the dynamic interplay between peripheral blood and inflammatory sites. INTRODUCTION: The aim of the current study was to define in Behçet's disease (BD), CD8+ T-cell subsets using CD28 and CD11b monoclonal antibodies, and the characterization of the Tc1/Tc2 ratio and perforin expression. METHODS: Flow cytometry was used for intracytoplasmic cytokines and perforin expression. Effector cells were investigated by adhesion of CD8+ T cells to human microvascular endothelial cells and by chemotaxis using beta-chemokine. RESULTS: Interferon-gamma-producing CD8+ T cells in active and remission BD patients were increased, which induce a significant increase of the Tc1:Tc2 ratio in BD. CD8(+)CD28(-)CD11b+ T cells were found to be more expanded in BD patients than in age-matched healthy controls. The expression of CD11b molecules in active BD allowed to CD8(+)CD28+/CD8(+)CD28- subsets to adhere to human microvascular endothelial cells, with more efficiency in BD. Using MIP-1alpha, we observed that the migratory process of CD28(-)CD11b(+) is more important in BD. CD28(-)CD11b+ exhibited an increased perforin expression in BD patients. CONCLUSION: Taken together these results suggest the presence of immune activation, probably in response to a profound inflammation affecting BD patients. The physiopathological significance of these results were toward autoimmune diseases and/or infectious process.

Perforin expression is upregulated in the epidermis of psoriatic lesions

BACKGROUND

There are currently very few data regarding the role of cell-mediated cytotoxicity in psoriasis. Both cytotoxic T lymphocytes and natural killer (NK) cells mediate cytotoxicity reactions, mainly by two distinct pathways, the perforin/granzyme and the Fas/Fas ligand pathway.

OBJECTIVES

To study the expression and distribution of perforin, T- and NK-cell subsets in psoriatic lesional and nonlesional skin.

METHODS

Skin biopsy specimens from both lesional and nonlesional skin of 11 patients with chronic plaque psoriasis and eight healthy controls were analysed by immunohistochemistry.

RESULTS

We found a significant increase in CD4+ and CD8+ cells in psoriatic lesions compared with nonlesional and healthy skin. The expression of CD16+ NK cells was significantly lower in lesions compared with healthy skin. Perforin expression was significantly enhanced in the epidermis of psoriatic lesions.

CONCLUSIONS

Perforin expression is upregulated in the epidermis of psoriatic lesions, suggesting a potential role for perforin in the creation of the psoriatic plaque.

The role of perforin-mediated apoptosis in lichen planus lesions

Lichen planus is recognized as a T-cell-mediated disease. Histologically, it is characterized by the formation of colloid bodies representing apoptotic keratinocytes. The apoptotic process mediated by CD8(+) cytotoxic T lymphocytes (CTLs) and NK cells mainly involves two distinct pathways: the perforin/granzyme pathway and the Fas/FasL pathway. So far, little is known regarding the role of perforin-mediated apoptosis in lichen planus. In the present study, the expression and distribution of perforin, T and NK cell subsets in the epidermis and dermis of lesional and nonlesional lichen planus skin were studied. Skin biopsy specimens from lesional and nonlesional skin of ten patients with lichen planus and eight healthy persons were analysed by immunohistochemistry. Significant accumulation of T cells, particularly of CD4(+) and CD8(+) subsets, was found in both epidermis and dermis of lichen planus lesions compared with nonlesional and healthy skin. There were no significant differences in the incidence of NK cells (CD16(+) and CD56(+)) between lesional, nonlesional and healthy skin. Perforin expression was significantly upregulated in the epidermis of lichen planus lesions. In conclusion, accumulation of perforin(+) cells in the epidermis of lichen planus lesions suggest a potential role of perforin in the apoptosis of basal keratinocytes.

Routine flow cytometric immuno-staining of T-cell perforin is preserved using diethylene glycol for erythrocyte-lysis but lost by the use of ammonium chloride

The system of perforin-containing lytic granules of cytotoxic lymphocytes plays an important role in the immune defense machinery. Investigating the capacity and efficacy of this system in and ex vivo is helpful to understand immune responses and their modulation by therapeutic interventions. With regard to its pathophysiological function, we recently demonstrated a substantial increase of perforin-positive CD8+ T cells in the peripheral blood of patients with acute exacerbated psoriasis and severe generalized drug reactions, and, in marked contrast, a highly significant perforin-depletion and a perforin-hyperreleasability in atopic dermatitis (AD). To streamline the perforin staining procedure, isolation of peripheral blood mononuclear cells (PBMC) by Ficoll density centrifugation was to be replaced by lysis of erythrocytes. Ammonium chloride lysis, however, reduced the perforin content of CD8+ T cells substantially (up to 75-100%) as compared with Ficoll isolation of PMC. Incubation of cells in concanamycin A, a selective inhibitor of H+-ATPases, resulted in a similar loss of perforin staining pointing to the critical influence of lysosomal pH. Using diethylene glycol-mediated erythrocyte lysis, perforin was well preserved to be readily detectable by immuno flow cytometry. Representative examples of the application of this optimized perforin staining procedure as well as accumulated data are given for various dermatological disorders (psoriasis, atopic dermatitis, cutaneous drug reactions, graft-versus-host disease (GVHD) with strong involvement of the cytotoxic T-cell population. Our findings may help to explain recent conflicting reports about a widely varying range of the portion of perforin-positive cells in healthy individuals as a reflection of such artificial methodological influences.

Perforin expression in peripheral blood lymphocytes and skin-infiltrating cells in patients with lichen planus

BACKGROUND

Current evidence suggests that lichen planus is a T-cell-mediated autoimmune disease in which cytotoxic mechanisms have been poorly investigated.

OBJECTIVES

We investigated the expression of perforin in subpopulations of peripheral blood lymphocytes (PBL) in exacerbation and remission phases of the disease as well as in skin lesions.

METHODS

We performed a simultaneous detection of perforin (intracellular molecule) and cell surface antigens on PBL by flow cytometry, and skin lesions were investigated by immunohistochemistry.

RESULTS

The most interesting finding was a significant increase of perforin expression in cytotoxic T lymphocytes (CD3+ perforin+ cells) in the exacerbation phase of disease (P < 0.05), which was mostly located in the CD8+ subpopulation (CD8+ perforin+) (P < 0.01). Using immunohistochemistry we confirmed the infiltration of T lymphocytes in skin lesions, especially of CD4+ and CD8+ phenotypes, compared with uninvolved (P < 0.05) and healthy skin (P < 0.01). The expression of perforin was also significantly higher in lesional skin compared with nonlesional and healthy skin (P < 0.05).

CONCLUSIONS

Our results clearly show the upregulation of perforin expression in peripheral blood as well as in lesions of patients with lichen planus and therefore suggest an important role for perforin in this autoimmune disease.

The defect of the perforin granule system in cytotoxic T lymphocytes of atopic patients - are perforin reduction and hyperreleasability of clinical relevance? Zum Defekt des Perforin-Granulasystems zytotoxischer T-Lymphozyten bei Patienten mit Atopie - Sind Perforin-Reduktion und -Hyperreleasability klinisch relevant?

Perforin-containing lytic granules are secretory lysosomes of cytotoxic lymphocytes. They act as a negative regulator of activated T cells, control immunoglobulin production, contribute to the regulation of the TH1/TH2 balance, and occupy a central role in anti-viral defense mechanisms. This review focuses on recent evidence for a fundamental defect in the lymphocytic perforin system of atopic patients, namely perforin reduction and the hyperreleasability of perforin granules. These findings are set in relation to the immune imbalance in atopy, which is characterized by a weakly restrained proliferation of allergen-specific T and B cells, a predominance of Ttype-2 cytokines, and an increased susceptibility to cutaneous infections. In the context of the wellknown defect of secretory lysosomes in mast cells and keratinocytes of atopic patients, the possibility of a cell type-independent major pathological factor in atopy is discussed: pan-cellular reduction and hyperreleasability of secretory lysosomes.

Dual functions of fractalkine/CX3C ligand 1 in trafficking of perforin+/granzyme B+ cytotoxic effector lymphocytes that are defined by CX3CR1 expression

Fractalkine/CX3C ligand 1 and its receptor CX3CR1 are known to mediate both cell adhesion and cell migration. Here we show that CX3CR1 defines peripheral blood cytotoxic effector lymphocytes commonly armed with intracellular perforin and granzyme B, which include NK cells, gammadelta T cells, and terminally differentiated CD8(+) T cells. In addition, soluble fractalkine preferentially induced migration of cytotoxic effector lymphocytes. Furthermore, interaction of cytotoxic effector lymphocytes with membrane-bound fractalkine promoted subsequent migration to the secondary chemokines, such as macrophage inflammatory protein-1beta/CC ligand 4 or IL-8/CXC ligand 8. Thus, fractalkine expressed on inflamed endothelium may function as a vascular regulator for cytotoxic effector lymphocytes, regardless of their lineage and mode of target cell recognition, through its ability to capture them from blood flow and to promote their emigration in response to other chemokines.

Increased cytotoxic T cells with effector phenotype in aplastic anemia and myelodysplasia

OBJECTIVE

We hypothesized that an active autoimmune process in aplastic anemia (AA) corresponds to the expansion of cytotoxic lymphocytes (CTLs) displaying mature effector phenotype. We determined whether the numbers of effector CTLs in blood of patients with bone marrow failure syndromes are elevated and correlate with the disease activity and responsiveness to immunosuppression.

PATIENTS AND METHODS

We analyzed samples from patients with AA, myelodysplastic syndrome (MDS), polytransfused patients with nonimmune-mediated hematologic disease, and normal controls for the presence of effector T lymphocytes using four-color flow cytometry. Expression of CD57 and loss of CD28 on CD8+CD3+ CTL were used as markers for the terminal effector phenotype. In addition, intracellular staining for perforin and granzyme B was preformed. The numbers of effector CTL did not differ between healthy individuals and hematologic controls and the two groups were pooled.

RESULTS

The percentages of CD8+CD28- and CD8+CD28-CD57+ cells were significantly higher in AA and MDS patients than in controls. There was a trend toward a gradual decrease in the effector CTLs from the high values observed in untreated new patients and patients who did not respond to immunosuppression, intermediate levels for partial responders and complete responders, to the lowest levels seen in controls. However, severity of pancytopenia did not correlate with the size of the effector cell population. In contrast to CD57+ CTLs, expression of perforin or granzyme B in the cytotoxic effector cells did not differ in AA patients from those of controls.

CONCLUSIONS

Our results indicate that phenotypically defined effector CTLs are increased in AA and MDS and the effector phenotype may be useful to isolate and characterize antigen-specific T cells in AA in order to delineate the possible inciting or driving agents in AA.

Perforin hyperreleasability and depletion in cytotoxic T cells from patients with exacerbated atopic dermatitis and asymptomatic rhinoconjunctivitis allergica

BACKGROUND

As a plasma membrane pore-forming protein, perforin is essential for T-cell cytotoxicity mediated by lytic granules. Recent studies on the immune system of perforin knockout mice demonstrated striking similarities to the immunopathology of atopic diseases.

OBJECTIVE

We sought to investigate the perforin system of atopic patients.

METHODS

Monoclonal antibodies were used to characterize perforin-positive PBMCs of patients with exacerbated atopic dermatitis (AD) and asymptomatic rhinoconjunctivitis allergica (RCA) by means of immunoflow cytometry. In addition, a perforin release assay was developed to quantify the velocity of ionomycin and phorbol 12-myristate 13-acetate-induced secretion of lytic granules.

RESULTS

In atopic patients significantly fewer lymphocytes contained perforin-positive lytic granules compared with those of healthy control subjects (patients with AD: 14% +/- 5%, n = 13, P <.0001; patients with RCA: 24% +/- 5%, n = 9, P <.01; healthy control subjects: 33% +/- 11%, n = 13). Of all CD8(hi+) cytotoxic T lymphocytes (CTLs), only 18% +/- 9% and 17% +/- 12% were perforin-positive in patients with AD and RCA, respectively, compared with 44% +/- 13% in control subjects (P <.0001). In addition, perforin-positive CD8(hi+) CTLs of atopic patients released their perforin twice as fast and more completely than control CTLs. This means that 50% of initially perforin-positive CD8(hi+) CTLs from patients with AD and RCA released their perforin completely within 32 +/- 16 and 36 +/- 19 minutes, respectively, and an over 85% release was reached within 113 +/- 41 and 118 +/- 60 minutes, respectively. In CTLs of healthy control subjects, however, it took 64 +/- 40 minutes to achieve a 50% release of lytic granules, and an 85% depletion was not reached in 60% of healthy control subjects, even after 180 minutes.

CONCLUSION

The perforin hyperreleasability explains, at least in part, the decreased percentage of perforin-positive CD8(hi+) CTLs in atopic patients. These distortions in the system of lytic granules of atopic patients may contribute to the functional defects observed in T-cell cytotoxicity in vivo and in vitro in patients with AD and RCA.

Increase in perforin-positive peripheral blood lymphocytes in extrinsic and intrinsic asthma

The cause of asthma, which has been linked to a chronic, T-cell-mediated bronchial inflammation, remains unclear. A number of other T-lymphocyte-mediated, chronic inflammatory disorders have been associated with autoimmunity and there are data indicating that autoimmune phenomena might also be present in asthma. Expression of perforin, a cytotoxic molecule produced by lymphocytes, has been implicated in the pathogenesis of autoimmune diseases. We therefore tested the hypothesis that allergic and intrinsic asthma might be associated with an increase in lymphocytes producing perforin by comparing the expression of intracellular perforin in peripheral blood lymphocytes of patients with extrinsic asthma (n = 13), intrinsic asthma (n = 7), and healthy control subjects (n = 18). Lymphocytes were identified using flow cytometry and subdivided into CD3(+), CD4(+), CD8(+), CD16(+), and CD56(+) subpopulations after staining with appropriate monoclonal antibodies. The percentage of perforin-positive total lymphocytes was significantly elevated in patients with allergic as well as intrinsic asthma when compared with normal control subjects. Analysis of lymphocyte subpopulations also revealed a significant increase in the percentage of CD3(+), CD4(+), CD8(+), and CD56(+) cells expressing perforin in allergic asthma and a significant increase in the percentage of CD4(+) and CD56(+) cells in intrinsic asthma when compared with healthy control subjects. Perforin expression in CD4(+) cells in intrinsic asthma was also significantly elevated compared with allergic asthma. We conclude that allergic and intrinsic asthma is associated with increased expression of perforin in T-lymphocyte subsets.

High numbers of perforin mRNA expressing CSF cells in multiple sclerosis patients with gadolinium-enhancing brain MRI lesions

Enhanced expression of pro- and anti-inflammatory cytokines is a common finding in MS, but attempts to correlate cytokine expression with disease activity have produced conflicting results. In this paper, gadolinium-(Gd-)enhancing lesions on brain MRI were used as markers for active inflammation in patients with MS not treated with any immunomodulatory drugs. In parallel, in situ hybridization was used to detect blood and cerebrospinal fluid (CSF) mononuclear cells (MNC) expressing cytokine mRNA. An association was observed between numbers of perforin mRNA expressing CSF MNC and numbers of Gd-enhancing brain MRI lesions. Perforin mRNA expressing CSF MNC were not detected in any of the patients lacking active lesions on brain MRI. The expression of tumor necrosis factor-alpha, interleukin-10 (IL-10) and IL-12 mRNA in CSF MNC did not differ between MS patients with and without active MRI lesions. Based on the present finding, a role for perforin in the disruption of the blood-brain barrier in MS can be hypothesized.

Age-Related Decline of Perforin Expression in Human Cytotoxic T Lymphocytes and Natural Killer Cells

In this study a flow cytometric technique for detecting cytoplasmic perforin (P) has been used to quantify age-related changes in perforin expression in human peripheral blood lymphocytes (PBL). Proportions of P+ lymphocytes increased after birth, but declined rapidly after the age of 70 years. This was true for both T cells and CD16+ and CD56+ natural killer (NK) cells. Children showed in addition to high levels of perforin positive CD8+ cells a much higher proportion of CD4+P+ cells than the other age groups. In elderly individuals there was also a highly significant reduction in mean levels of perforin per cell as compared with all other groups (P < .05 to .001). Adult women had consistently higher mean levels of perforin per cell than adult men for all P+cell phenotypes. Functional tests clearly showed the deficiency in early spontaneous cytotoxic potential of PBL from elderly persons due to relative P deficiency, which can be corrected by stimulation of cytolytic cells with target cells and interleukin-2 (IL-2). The deficiency in cytolytic activity on the contact with target cells may have implications for antiviral and antitumor immunity in elderly persons.

Age-Related Decline of Perforin Expression in Human Cytotoxic T Lymphocytes and Natural Killer Cells

In this study a flow cytometric technique for detecting cytoplasmic perforin (P) has been used to quantify age-related changes in perforin expression in human peripheral blood lymphocytes (PBL). Proportions of P+ lymphocytes increased after birth, but declined rapidly after the age of 70 years. This was true for both T cells and CD16+ and CD56+ natural killer (NK) cells. Children showed in addition to high levels of perforin positive CD8+ cells a much higher proportion of CD4+P+ cells than the other age groups. In elderly individuals there was also a highly significant reduction in mean levels of perforin per cell as compared with all other groups (P < .05 to .001). Adult women had consistently higher mean levels of perforin per cell than adult men for all P+cell phenotypes. Functional tests clearly showed the deficiency in early spontaneous cytotoxic potential of PBL from elderly persons due to relative P deficiency, which can be corrected by stimulation of cytolytic cells with target cells and interleukin-2 (IL-2). The deficiency in cytolytic activity on the contact with target cells may have implications for antiviral and antitumor immunity in elderly persons.