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

The impact of allergen exposure and specific immunotherapy on circulating blood cells in allergic rhinitis

Allergic rhinitis (AR) is an IgE-mediated inflammatory disease of the nasal mucosa with well described local immune responses during allergen exposure. The frequent association of AR with general extra-nasal symptoms and other allergic conditions, such as conjunctivitis and asthma, however, support a more systemic disease impact. In addition to acute elevation of soluble inflammatory mediators in periphery blood, a growing number of studies have reported changes in circulating blood cells after specific nasal allergen challenge or environmental allergen exposure. These findings imply an involvement of specific blood leukocyte subsets, thrombocytes and recently, erythrocytes. This review summarizes the circulating blood cell dynamics associated with allergen exposure in AR subjects reported so far. Additionally, the impact of therapy, particularly allergen-specific immunotherapy (AIT), the only currently available causal treatment reducing AR-related symptoms, is further considered in this context.

Impetiginized Dyshidrotic Eczema

A 16 years old female patient, affected by atopic dermatitis and rhinoconjunctivitis allergica since childhood, requested a dermatologic consultation for lesions which had appeared after 3 months of local treatment with clobethasole propionate. The histological analysis confirmed the diagnosis of dyshidrotic eczema and the microbiological smears demonstrated a significant infection with Staphylococcus aureus. The risk of developing corticosteroids’ side-effects depends on the potency of the product, extended period of use and the volume of product applied. Clobetasol propionate is a group I- highly potent corticosteroid, which should be used for a maximum period of 2 weeks. Several authors have found that this agent has cumulative depot effect, persisting in the epidermis for 4 days after only one application. Taking together these observations, sustained by the clinical case presented above, we can conclude that the infectious risks associated with topical corticosteroid treatment must not be neglected, particularly since treated patients are fragile, and frequently have multiple well-known risk factors.

Plasma adrenomedullin levels in children with asthma: any relation with atopic dermatitis?

BACKGROUND

Asthma is a chronic, inflammatory disease of the airway, and adrenomedullin (ADM) may have some effects against bronchoconstriction. However, the role(s) of ADM in asthmatic children have not been evaluated yet. The aims of this study were to determine if there are any changes in plasma ADM levels during acute asthma attack, and to search for any association between allergen sensitivity and ADM level in asthmatic children.

METHODS

Twenty-seven children with acute asthma attack, ranging in age from 5 to 15 years were investigated and compared with 20 controls. Plasma ADM levels (ng/mL) were measured by ELISA method.

RESULTS

No significant difference was found in ADM levels between the controls and patients in either the acute attack or remission period. Plasma ADM levels were significantly higher in the acute attack (p=0.043) compared to the remission period in patients who were considered as having a "severe attack" according to GINA (Global Initiative for Asthma) classification. There were statistically significant correlations between the patients' AlaTOP and Food Panel 7 levels and plasma ADM levels in the acute attack period (p=0.010, p=0.001, respectively). The ADM levels in patients with a history of atopic dermatitis were significantly higher in the acute attack period compared to those without a history of atopic dermatitis (p=0.007).

CONCLUSION

We speculate that ADM may have a role in children with atopic dermatitis, and may also have a role in the immuno-inflammatory process of asthma.

CD8+ T cell activation and differentiation in allergic asthma and the impact of cytomegalovirus serological status

Allergic asthma is a chronic inflammatory T helper 2 (Th2)-associated disease. There is evidence that the atopic milieu affects the development of CD8(+) T cells in patients. We therefore analysed activation and differentiation states of CD8(+) T cells in asymptomatic patients regarding the cytomegalovirus serological status. Memory CD8(+) T cells (CCR5(high)CD3(+)CD8(+)), memory/effector cells (CD27(+)CD28(-)CD3(+)CD8(+)), effector cells (CD27(-)CD28(-)CD3(+)CD8(+)) and activated CD8(+) T cells (CD11b(+)CD3(+)CD8(+)) were identified by flow cytometry in peripheral blood of 19 (seven cytomegalovirus (CMV)(+)/12 CMV(-)) patients with allergic asthma (AA) and 21 (seven CMV(+)/14 CMV(-)) healthy controls (HC). Effector and activated CD8(+) T cells were significantly elevated in CMV(+) HC compared to CMV(-) HC. There was a non-significant trend for reduced percentages of effector CD8(+) T cells in CMV(+) AA (median: 10.4%, range: 4.4-33.8%) compared to CMV(+) HC (median: 23.1%, range: 10.7-54.1%; P = 0.128) and in CMV(-) AA (median: 4.1%, range: 0.6-13.4%) compared to CMV(-) HC (median: 5.7%, range: 0.2-17.0%; P = 0.085). Activated CD8(+) T cells were reduced significantly in CMV(+) AA (median: 17.0%, range: 6.0-29.4%) compared to CMV(+) HC (median: 40.4%, range: 18.9-67.0%; P = 0.004) and showed a non-significant trend in CMV(-) AA (median: 15.0%, range: 2.9-24.0%) compared to CMV(-) HC (median: 20.2%, range: 5.8-71.0%; P = 0.060). Activated CD8(+) T cells are significantly reduced in CMV(+) patients with allergic asthma. Furthermore, a trend for an impaired terminal CD8(+) T cell differentiation is observed in CMV(+) and CMV(-) patients with asthma.

Decrease of cytotoxic T cells in allergic asthma correlates with total serum immunglobulin E

BACKGROUND

Allergic asthma has been linked to an increase in T-helper type 2-like cytokines and T cells, but there is growing evidence for a role of lymphocyte-mediated cytotoxic mechanisms in the pathogenesis of asthma. Therefore, we investigated the cytotoxic potential of different lymphocyte subpopulations in patients with allergic asthma.

METHODS

Granzyme A, B, K, and perforin expression in peripheral blood lymphocytes was analyzed using flow cytometry. Soluble granzymes were measured in serum using specific enzyme-linked immunosorbent assays.

RESULTS

Asthmatics had significantly decreased percentages of granzyme and perforin-positive CD4 T cells compared with non-atopic controls. In patients with asthma, the granzyme B and perforin-positive subset of CD8(+) T cells and natural killer T cells, which represent more differentiated cell populations, were significantly reduced, while this was not observed in the less differentiated granzyme K(+) subsets. In addition, the serum concentrations of granzyme B were significantly reduced in patients with asthma, while granzyme K concentrations were not different. Interestingly, there was a negative correlation between granzyme A, B and perforin expression in T cell subsets as well as serum granzyme B concentrations and total serum immunglobulin E. In CD3-negative natural killer cells, no differences in granzyme or perforin expression between patients with asthma and controls were detected.

CONCLUSION

In allergic asthma, cytotoxic T lymphocyte subsets of a more differentiated phenotype are significantly decreased and this is correlated to serum immunglobulin E levels.

A novel flow cytometric assay focusing on perforin release mechanisms of cytotoxic T lymphocytes

CD8(hi+) cytotoxic T lymphocytes (CTL) are major players in immune defense. In addition, they contribute to the maintenance of immune homeostasis. We now describe a hitherto unavailable, but simple assay to determine ex vivo lytic granule-based cytotoxic functions of human CD8(hi+) CTL subgroups in a clinical setting, under target cell free conditions. Ficoll-isolated peripheral blood lymphocytes from 17 healthy volunteers were stimulated either by phorbol 12-myristate 13-acetate (PMA) in combination with ionomycin or by antibody mediated crosslinking of the CD3 molecule on the T cell surface. Using perforin as a marker for lytic granules, the reduction of CTL granules over time intervals up to 120 min was quantified by FACScan flow cytometry. The kinetics of perforin reduction were compared to the kinetics of NA-CBZ-L-lysine-thiobenzyl ester hydrochloride (BLT)-esterase release and of CD63 upregulation. The reduction in the perforin(+) portion of CD8(hi+) CTLs was correlated inversely with BLT-esterase release and CD63 upregulation. At 30 and 120 min after PMA/ionomycin stimulation, 55 +/- 14% and 42 +/- 14%, respectively, of CD8(hi+) CTLs still stained perforin(+) (time point 0 min = 100%). Perforin-granule release induced by CD3-crosslinking occurred as fast within 30 min (55 +/- 17%), but over the 120 min time interval it was not as complete when compared to PMA/ionomycin-stimulated perforin-reduction. Thus, the combination of an established degranulation assay with the power of immuno flow cytometry allows one to investigate the cytotoxic capability of CTL-subtypes and the kinetics of perforin-granule release. In addition, the assay may prove useful in the elucidation of intracellular signaling cascades governing the perforin-granule release process.

UVA1 radiation (340–400nm) interferes with the perforin-granule system of CD8hi+ cytotoxic T lymphocytes in vitro

UVA1-irradiation was introduced as an innovative and effective phototherapy of atopic dermatitis (AD) and other skin diseases. In AD, a defect of a central apoptosis inducing effector system involved in immunoregulation and immune defense, i.e., the system of perforin-granules in cytotoxic T lymphocytes (CTL), was recently reported: perforin-reduction and perforin-hyperreleasability. We now investigated UVA1-effects on the perforin-granule system in vitro. Peripheral blood CTLs were exposed in vitro to 10-100 J/cm2 UVA1 (340-400 nm), and to 30-150 mJ/cm2 UVB (280-315 nm) as a control. A time-dependent perforin-granule release was induced by phorbol 12-myristate 13-acetate (PMA) and ionomycin. This release was inhibited dose-dependently by UVA1, but not by UVB. An UVA1-dose dependent pattern of sensitive (80%) and insensitive (20%) individuals was found. The kinetics of perforin release in AD-CTLs, i.e. hyperreleasability, was normalized by 50 J/cm2 UVA1 in vitro. Sodium azide as a quencher of reactive oxygen species prevented the UVA1-mediated inhibition of perforin-granule release. Our data demonstrate for the first time a dose- and wavelength-dependent UVA1-effect in vitro on a major effector system of cytotoxic lymphocytes, the system of perforin-granules. This might contribute to the further understanding of immunomodulatory UVA1-effects in vivo.

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.

Imiquimod, a Toll-like receptor-7 agonist, induces perforin in cytotoxic T lymphocytes in vitro

Imiquimod (IMQ), an activator of Toll-like receptor-7 (TLR-7), induces by several routes a profound anti-viral and anti-tumor effect in vivo. Physiologically, the immune system is using perforin-containing granules of cytotoxic T lymphocytes (CTL) towards the same biological purpose. This functional synergism prompted our current experiments addressing the question whether IMQ may influence perforin-release and/or induce perforin in CTLs in vitro. In peripheral lymphocytes of healthy and diseased subjects, IMQ induced a significant increase of perforin(+) CTLs within 12h in all experiments performed. This effect was most pronounced in CTLs of patients suffering from atopic dermatitis, a model disorder for subnormal perforin expression: as compared to perforin(+) CTLs detected at time point zero (100%), up to 270% of perforin(+) CTLs were induced by 2.5 microg/ml [corrected] IMQ. Perforin release from peripheral blood CTLs after PMA/ionomycin-stimulation was not influenced significantly by IMQ. Thus, the biological activity of IMQ appears to exceed its previously known functions, inasmuch as it boosts up significantly the perforin-granule system.

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.

Advances in allergic skin diseases

During the past year there have been significant advances in our understanding of the mechanisms underlying allergic skin diseases. This article reviews some of these advances in atopic dermatitis and urticaria. The introduction of a new class of topical anti-inflammatory medications, topical calcineurin inhibitors, has significantly increased our treatment options and led to a rethinking of potential management approaches in atopic dermatitis.

Atopic dermatitis

Atopic dermatitis is a highly pruritic chronic inflammatory skin disorder affecting 10-20% of children worldwide. Symptoms can persist or begin in adulthood. It is also the most common cause of occupational skin disease in adults. This disease results from an interaction between susceptibility genes, the host's environment, pharmacological abnormalities, skin barrier defects, and immunological factors. New management approaches have evolved from advances in our understanding of the pathobiology of this common skin disorder.

Smallpox vaccination: Risk considerations for patients with atopic dermatitis

As the threat of bioterrorism with pathogenic microbes such as smallpox virus (Variola major) increases, the question of widespread voluntary vaccination with smallpox (vaccinia) vaccines is being carefully considered. A major challenge lies in the ability to protect the population from the disease while minimizing the considerable side effects from the vaccine. Individuals with active or quiescent atopic dermatitis are at increased risk for vaccinia complications. The nature of these complications and other considerations are summarized in this rostrum.