Alpha 1-proteinase inhibitor in psoriasis: reduced activity in symptom-free patients and during flare

Calcitriol inhibits keratinocyte proliferation by upregulating leukocyte elastase inhibitor (serpin B1)

Calcitriol had been proved to be effective for treatment of psoriasis vulgaris. However, the molecular events leading to the normalization of keratinocyte differentiation had not been fully explored. The aim of the study was to evaluate the role of calcitriol and serpin B1 in human keratinocyte cell line (HaCaT) proliferation. Proteins extracted from calcitriol-treated and untreated HaCaT were separated by 2-D differential gel electrophoresis (2DE). Then, the 2DE profiles were analyzed to screen for differentially expressed proteins, which were identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry. The upregulation of serpin B1 was confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis. The effect of serpin B1 on HaCaT proliferation was analyzed by RNA interference experiments, methylthiazoletetrazolium assay and flow cytometry. Reproducible 2-DE profiles of HaCaT were established. The result that serpin B1 was upregulated in the calcitriol-treated group was confirmed by qRT-PCR and western blot analysis. Calcitriol could inhibit proliferation of HaCaT at the concentration of 10(-9) -10(-6 ) mol/L. HaCaT proliferation was promoted when serpin B1 was interfered. The inhibition effect of calcitriol was stopped after serpin B1 was interfered. Serpin B1 was overexpressed in calcitriol-treated HaCaT cells and may play an important role in inhibiting HaCaT proliferation by calcitriol.

Critical role of neutrophils for the generation of psoriasiform skin lesions in flaky skin mice

Although T cell dysregulation is thought to underlie the pathogenesis of psoriasis, prominent infiltration and microabscess formation by neutrophils is a distinctive hallmark feature of this common disorder. The exact role of neutrophils in the pathogenesis of psoriasiform alterations in vivo, however, is unknown. Similar to human psoriasis, flaky skin mice (fsn/fsn) revealed a prominent infiltrate of neutrophils, and microabscesses within the hyperproliferative epidermis were associated with de novo expression of intercellular adhesion molecule-1. Intraperitoneal injection with the neutrophil-depleting RB6-8C5 monoclonal antibody (anti-Ly-6G) resulted in a dramatic reduction of the epidermal thickness by 58% compared with isotype-treated animals (p < 0.001). In addition, epidermal microabscesses were conspicuously absent (p < 0.001), and cutaneous neutrophils and T cells, but not mast cells or dendritic cells, were markedly reduced in anti-Ly-6G-treated mice. Proinflammatory cytokines, including tumor necrosis factor alpha and interleukin-1, were also downregulated. Therapeutic effects occurred as early as 4 d after beginning of treatment. Wildtype skin was not affected. When the integrin alphaMbeta2 (CD11b/CD18), which mediates neutrophil localization through binding to intercellular adhesion molecule-1, was blocked in vivo with the M1/70 monoclonal antibody, the epidermal thickness was reduced by 31% (p < 0.002), and neutrophil and T cell accumulation was diminished compared with control animals. Likewise, treatment of fsn/fsn mice with the MP1-22E9 monoclonal antibody neutralizing granulocyte macrophage-colony stimulating factor, a cytokine stimulating neutrophils by upregulating alphaMbeta2, resulted in significant reduction of inflammation and acanthosis by 30% (p < 0.003). These results demonstrate a critical pathogenic role of neutrophils for hyperproliferative inflammatory lesions in fsn/fsn mice, suggesting that blocking neutrophil function may have therapeutic benefit in some human skin disorders.

Neuropeptides in psoriasis: possible role of beta-endorphin in the pathomechanism of the disease

BACKGROUND

An increased concentration of neuropeptides in psoriatic lesional skin may be responsible for alterations in the neurogenic erythematous response and transmission of stimuli through sensory nerve fibers (sensation of pruritus).

METHODS

Increasing doses of capsaicin from 0.125 to 4 micrograms/cm2 were applied to nonlesional psoriatic skin to establish the minimal dose that induced the substance P-mediated neurogenic response in 30 patients with psoriasis. Plasma beta-endorphin was quantitated in 71 psoriatics by radioimmunoassay using NEN 1251-RIA kit.

RESULTS

The mean beta-endorphin concentration was increased about 2-fold compared to normals, whereas doses of capsaicin needed to induce erythema were higher (1-4 micrograms/cm2) in psoriatics (mainly in patients with type II psoriasis) than in healthy subjects (0.125-0.25 microgram/cm2).

CONCLUSIONS

The data indicate that increased beta-endorphin in psoriatic skin might affect both substance P-mediated neurogenic inflammation and transmission of sensory stimuli due to local antinociceptive effects of this opioid. The differences in the neurogenic response in type I and II psoriasis may be related to the degradation of substance P and beta-endorphin by neutral proteinases in the lesional skin.

Laboratory findings and pathology of psoriatic arthritis

Over recent years there has been a great deal of interest in the immunology, molecular biology and pathology of psoriasis and PsA. The pathogenetic mechanisms in PsA are less well understood than those described for psoriasis. There are almost certainly genetic and immune components. What is not clear is whether there is a primary immune defect or whether unknown stimuli lead to the recruitment of the immune system and establishment of the disease; nor is it absolutely clear whether PsA is an extension of psoriasis in certain prone individuals. Vascular abnormalities are the earliest histopathological changes to occur in the psoriatic plaque and are also prominent in the psoriatic synovium. Espinoza et al (1982) have suggested there may be a primary vascular defect in PsA. The fact that vascular changes occur before infiltration of immunocompetent cells and are the first changes to resolve with treatment of psoriasis is likely to be significant. Abnormalities in the cellular kinetics and growth factor sensitivity of keratinocytes, fibroblasts and synoviocytes have been highlighted previously. The ability of these cells to produce growth factors and express HLA class II antigens demonstrates the potential for them to initiate and maintain inflammation. The development and possible increased incidence of PsA in patients with such profound immunodeficiency as acquired immune deficiency syndrome suggests that T helper cells do not play a significant role in the establishment of the disease (Arnett et al, 1991). Previously, many immune changes were described. Unfortunately they are non-specific and do not indicate a fundamental defect or marker of PsA. Vasey (1985) has suggested that insidious exposure to Gram-positive bacteria from the gut, tonsils and psoriatic plaques results in chronically stimulated monocytes, macrophages and dendritic cells. These cells are able to migrate throughout the body. Repeated microtrauma may result in the homing of these cells to sites of injury in the skin, synovium and tendons. Interaction with genetically hyperactive synoviocytes and keratinocytes with concomitant release of growth factors may precipitate early lesions of psoriasis and PsA. This hypothesis needs to be substantiated, but it ties together some of the varying observations seen. Many abnormal laboratory findings have been described. Unfortunately, none of the serological changes is sufficiently specific to be of great help in diagnosis. CRP levels and the ESR remain the best promise as markers of the inflammatory component of the arthritis, while other indicators correlate with certain facets of the disease pathology, but as yet have not found a true niche in the management of PsA.(ABSTRACT TRUNCATED AT 400 WORDS)

Decreased specific anti-elastase activity in the uninvolved skin of patients with psoriasis

Inhibitory activities against elastase, chymotrypsin and trypsin were studied in the fluid from experimentally developed suction blisters in the uninvolved skin of patients with psoriasis. These activities determined by spectrophotometry of specific synthetic low molecular weight substrates were compared with respective antiproteinase activities in sera of 32 patients with psoriatic lesions, ten patients in remission, and ten healthy volunteers. A marked reduction (29.2%) in the specific elastase inhibitory activity of blister fluid was found in patients with psoriasis when compared with normal subjects (p less than 0.05), since neither chymotrypsin nor trypsin inhibitory activities were altered. This reduction was despite about a 30% increase in the elastase inhibitory activity in the sera of these patients, which was related presumably to their increased activity of alpha 1-proteinase inhibitor, the main serum antiserine proteinase inhibitor. A decreased blister fluid:serum elastase inhibition ratio was shown in a large majority of patients with psoriasis, even in symptomless patients. The deficiency in specific elastase inhibitory activity of suction blister fluid was predominantly associated with early onset of psoriasis, guttate lesions and inactive lesions, skin involvement less than 20% of body surface, duration of relapse shorter than 2 months, and frequent relapses. These data indicate that the uninvolved skin of patients with psoriasis contains low concentrations of specific elastase tissue inhibitor, which deficiency might result in an excessive in vivo hydrolytic activity of neutrophil elastase released from migrating cells in the psoriatic skin.

Basement membrane zone as a target for human neutrophil elastase in psoriasis

Human neutrophil elastase was found, by indirect immunofluorescence using rabbit anti-elastase anti-serum, to be bound to basement membrane of psoriatic plaques in vivo. The enzyme was also identified inside the migrating neutrophils in the reticular dermis and dermal papillae, as well as outside the cells in micro-abscesses in psoriatic skin. In vitro incubation of normal skin with human neutrophil elastase resulted in the destruction of hemidesmosomes and separation of the epidermis from the dermis above localizations of bullous pemphigoid antigen. These findings are direct evidence that human neutrophil elastase could play a role in psoriasis in in vivo destruction of the epidermal-dermal junction.