Abnormal granulocyte morphology in patients with psoriasis

The NET, the trap and the pathogen: neutrophil extracellular traps in cutaneous immunity

Neutrophil extracellular traps (NETs), large chromatin structures casted with various proteins, are externalized by neutrophils upon induction by both self- and non-self-stimuli. It has become clear that NETs are potent triggers of inflammation in autoimmune skin diseases. Moreover, the ability of NETs to trap pathogens suggests a crucial role in innate host defense. However, the outcome of the encounter between pathogens and NETs remains highly controversial. Here, we discuss recent insights into the morphology and formation of NETs, their role in skin inflammation and how NETs might contribute to host protection in skin infection.

Mast cells and neutrophils release IL-17 through extracellular trap formation in psoriasis

IL-17 and IL-23 are known to be absolutely central to psoriasis pathogenesis because drugs targeting either cytokine are highly effective treatments for this disease. The efficacy of these drugs has been attributed to blocking the function of IL-17-producing T cells and their IL-23-induced expansion. However, we demonstrate that mast cells and neutrophils, not T cells, are the predominant cell types that contain IL-17 in human skin. IL-17(+) mast cells and neutrophils are found at higher densities than IL-17(+) T cells in psoriasis lesions and frequently release IL-17 in the process of forming specialized structures called extracellular traps. Furthermore, we find that IL-23 and IL-1β can induce mast cell extracellular trap formation and degranulation of human mast cells. Release of IL-17 from innate immune cells may be central to the pathogenesis of psoriasis, representing a fundamental mechanism by which the IL-23-IL-17 axis mediates host defense and autoimmunity.

Domain structure of erythrocyte membranes in psoriasis: an EPR study

Membrane fluidity of erythrocytes from psoriatic patients in active and inactive period of the disease was studied by electron paramagnetic resonance (EPR). Comparison of simulated and experimental EPR spectra of erythrocyte membranes from controls and psoriatics showed that they are essentially superimposition of three components; two regions with a high degree of order of the lipid acyl chains and one region with poor alignments of hydrocarbon chains (with a small order parameter). In psoriatic erythrocytes not only the portion of the most rigid domain was enlarged, but also the order parameter of this domain was increased, while the order parameters of two other domains were the same than in normal erythrocytes. Results obtained in this article showed that the portion of the most rigid domain (W(A)) better correlated with polymorphonuclear elastase (PMN elastase) than with PASI score. Additionally, correlation between PMN elastase and W(A) in the active period of the disease was observed to be higher than in the inactive period. Therefore, portion of the most ordered domain (W(A)) seems to be a good marker for evaluation of the disease activity in psoriatic patients.

Characterization of skin-infiltrating lymphocytes in patients with psoriasis

In this study, skin-infiltrating cells in psoriasis patients were characterized in biopsies from both involved and uninvolved skin. Histologic examination of biopsies showed the presence of both CD4+ and CD8+ T cells and the lack of B lymphocytes. Skin biopsies were also placed in tissue culture medium supplemented with human serum, interleukin-2 (IL-2), and irradiated autologous blood lymphocytes. T lymphocytes grew from both plaques and univolved skin biopsies and consisted of a heterogeneous population of T-cell subsets. The immunophenotypic analysis of cultured cells was comparable to the histologic examination on frozen section, i.e., there was a greater number of CD4/CDw29+ cells than CD8+/CD45+ cells. Cultures were tested in the primed lymphocyte test (PLT) and cell-mediated lympholysis (CML) assays. All cultures tested demonstrated secondary proliferative but not cytolytic reactivity. The PLT results indicate that the cell cultures generated are autoreactive. This autoreactivity was found to be directed against non-human leukocyte antigens (HLA), i.e., minor HLA with some restriction to major HLA antigens.

Neutrophil leukocyte morphology, cigarette smoking, and palmoplantar pustulosis

Neutrophil leukocyte morphology was examined in whole blood films from 20 patients with palmoplantar pustulosis (PPP) and 32 healthy controls. In the PPP patients, there was a significant increase in the number of neutrophils having polarized morphology or membrane ruffling; however, there was no significant difference in neutrophil morphology between cigarette smokers and nonsmokers, suggesting that the epidemiologic link between smoking and PPP is not explained by increased polarization of peripheral blood neutrophils.

Myeloperoxidase of polymorphonuclear leukocytes in psoriasis vulgaris

The specific activity of myeloperoxidase (MPO), an enzyme located in the primary granules of polymorphonuclear leukocytes, was measured in patients with psoriasis vulgaris and compared with that in patients with atopic dermatitis and in healthy subjects. MPO catalyzes the oxidation of guaiacol into tetraguaiacol in the presence of H2O2. The activity was determined by photometric measurement of tetraguaiacol. The specific MPO activity showed no statistically significant difference between the healthy subjects and the patients with atopic dermatitis. In comparison to these two groups the specific MPO activity of the psoriatic patients showed a slight reduction which was, however, not statistically significant.

Increased IgG Fc and C3 rosette-forming capacity of granulocytes from patients with psoriasis

In the present work the proportions of IgG Fc and C3 rosette-forming granulocytes were studied in patients with severe psoriasis. The percentages of erythrocyte-antibody and C3 rosette-forming granulocytes from psoriasis patients were significantly higher than those of healthy individuals. Sera from patients with psoriasis did not influence the rosette formation by granulocytes from healthy persons. The increased IgG Fc and C3 receptor activities of granulocytes in psoriasis may account for the hyperactivity of these cells enhancing the susceptibility of the polymorphonuclears for at least some naturally occurring stimuli.