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Elafin is a potent reversible inhibitor of the pro-inflammatory proteases leukocyte elastase and protease 3. It is currently in clinical development for the use in postoperative inflammatory diseases. We investigated the pharmacokinetics of (99m)Tc-labeled elafin ((99m)Tc-Elafin) in blood and individual organs in rat after bolus intravenous injection using the single photon emission tomography (SPECT). (99m)Tc-Elafin predominantly accumulated in the kidney reaching a maximum of 8.5% ± 0.1% of the injected dose per gram (ID/g) at 5 min post injection (p.i) and decreased only slowly during 24 h. In contrast, the initially high radio activity recorded in the other organs rapidly decreased parallel to the radioactivity detected in blood. The blood kinetics fits to a two compartment kinetics model. The radio activity in the dissected kidney was 4.98 ± 1.24%ID/g 24 h p.i, while in other organs, including the brain, no accumulation of (99m)Tc-Elafin was detected. At this time point 30% of the detected radioactivity in the kidney was identified to be not metabolized (99m)Tc-Elafin. In conclusion, the blood and organ-specific kinetic data provide a basis for planning of adequate dosing regimens and the high accumulation of intact elafin in the kidney favors clinical developments targeting inflammatory kidney diseases, such as chronic allograft nephropathy after kidney transplantation., (Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

Elafin is an endogenous human protein composed of an N-terminal transglutaminase substrate motif and a C-terminal WAP (whey acidic protein)-domain with antiproteolytic properties. Elafin is expressed predominantly in epithelial tissue and potently inhibits the neutrophil-derived serine proteases elastase and proteinase-3 by a competitive tight-binding mechanism. Furthermore, it inhibits EVE (endogenous vascular elastase). Studies on several animal models show that antiprotease augmentation with human elafin is an effective strategy in the treatment of inflammatory vascular, systemic and pulmonary diseases and of inflammation triggered by reperfusion injury. This raises the possibility that elafin might be effective in the treatment of a variety of human inflammatory diseases. In a Phase I clinical trial, elafin was well tolerated. Phase II trials are underway to investigate the therapeutic effects of elafin on post-operative inflammation and the clinical consequences of major surgery. Of particular interest is the reduction of post-operative morbidity after oesophagus cancer surgery, coronary artery bypass surgery and kidney transplantation.

Purpose of Review: Neutrophil cells have been considered mainly as innate immune cells directed against microbial threats. Their serine proteases neutrophil elastase, proteinase 3 and cathepsin G are main constituents and are released at sites of inflammation. During recent years it became clear that neutrophil serine proteases act as regulators of cell signaling and immune regulation., Recent Findings: Neutrophils are able to form so-called neutrophil extracellular traps. Recent studies showed that these extracellular traps might be involved in small vessel vasculitis and lupus nephritis. Neutrophil serine proteases in concert with externalized nucleosomes promote thrombus formation inside blood vessels. This event helps retain bacteria inside liver microvessels and thereby prevents the extravasation of pathogens. Moreover, neutrophil serine proteases act as alternative processing enzymes of pro-inflammatory cytokines IL-1β and IL-18 in vivo and modulate other inflammation-related control mechanisms such as progranulin inactivation, matrix metalloproteinase-9 activation and IL-6 inactivation. Recent studies point to an involvement of neutrophil elastase in lung cancer by inducing mitogenesis after entering the cells., Summary: The knowledge of the different functions of neutrophils is still expanding. Recent findings underline the importance of neutrophil serine proteases as key mediators of inflammatory processes and point to novel strategies against inflammatory disorders.

Human gammadelta T cells rapidly secrete pro-inflammatory cytokines in response to T cell receptor-dependent recognition of pyrophosphates produced by many bacteria and parasites. In further support of an important role of gammadelta T cells in the immune defence against infection, human gammadelta T cells have been shown to produce the antimicrobial peptide LL37/cathelicidin. In this study, we have investigated whether gammadelta T cells can produce additional antimicrobial peptides. To this end, we have screened human gammadelta T cell clones by RT-PCR for mRNA expression of a broad range of antimicrobial peptides. While alpha-defensins were absent and beta-defensins (HBD1) present only in rare gammadelta T cell clones, elafin mRNA was induced by supernatant of Pseudomonas aeruginosa grown under static conditions. Elafin is a protease inhibitor that also displays antimicrobial activity. Constitutive intracellular expression of elafin was demonstrated by flow cytometry and Western blot analysis. Furthermore, trappin-2 (pre-elafin) could be immunoprecipitated in cell lysates but also in the supernatant of gammadelta T cells stimulated by Ps. aeruginosa supernatant. Taken together, our studies reveal a novel effector function of gammadelta T cells which might be important for local immune defence.

Abstract Porphyromonas gingivalis, the major causative bacterium of periodontitis, contributes significantly to elevated proteolytic activity at periodontal pockets owing to the presence of both bacteria and host, predominantly neutrophil-derived, serine proteases. Normally the activity of the latter enzymes is tightly regulated by endogenous proteins, including elafin, a potent neutrophil elastase and proteinase 3 inhibitor released from epithelial cells at sites of inflammation. Here, we report that all three gingipains (HRgpA, RgpB, and Kgp) have the ability to degrade elafin, with RgpB being far more efficient than other gingipains. RgpB efficiently inactivates the inhibitory activity of elafin at subnanomolar concentrations through proteolysis limited to the Arg22-Cys23 peptide bond within the surface loop harboring the inhibitor active site. Notably, elafin resists inactivation by several Staphylococcus aureus-derived serine and cysteine proteases, confirming the high stability of this protein against proteolytic degradation. Therefore, we conclude that elafin inactivation by RgpB represents a specific pathogenic adaptation of P. gingivalis to disturb the protease-protease inhibitor balance in the infected gingival tissue. This contributes to enhanced degradation of host proteins and generation of a pool of peptides serving as nutrients for this asaccharolytic pathogen.

Elafin (or skin-derived antileukoprotease) and secretory leukocyte protease inhibitor (SLPI) are serine antiproteases antagonizing human neutrophil elastase (HNE), thereby preventing tissue injury from excessive release of proteolytic enzymes by inflammatory cells. Furthermore, elafin and SLPI are "defensin-like" molecules with broad antimicrobial activity. The balance between proteases and antagonists may critically determine inflammatory processes in Crohn's disease (CD) and ulcerative colitis (UC). Real-time PCR was performed to quantitate colonic, proinflammatory cytokine IL-8, protease (HNE), and antiprotease mRNA (elafin and SLPI) in a total of 340 biopsies from 117 patients (47 CD, 45 UC, 25 controls). Histological inflammation was scored, and HNE, elafin, and SLPI were localized and semiquantified by immunostaining in 51 colonic paraffin sections (23 CD, 11 UC, 17 controls). Proinflammatory IL-8, degree of histological inflammation, and granulocyte content were similar in UC and CD. Elafin stained predominantly in the epithelium and SLPI in mucosal inflammatory cells. HNE mRNA levels and immunostaining were increased equally in both forms of inflammatory bowel disease. Levels of mRNA and immunostaining of the antiproteases elafin and SLPI were enhanced strongly in inflamed versus noninflamed UC. It is surprising that comparing inflamed versus noninflamed CD, this increase was significantly less pronounced for elafin and even lacking for SLPI. Despite comparable degrees of inflammation and protease levels, the induction of both antiproteases was attenuated in CD. This could contribute to the transmural depth of tissue destruction in CD. Elafin and SLPI may be added to the list of defensin-like peptides with diminished induction in CD versus UC.

Epidermal hyperproliferation and neutrophil infiltration are major histopathological changes observed in psoriasis. Neutrophils contain human leukocyte elastase (HLE), which is released at sites of inflammation. HLE is present in psoriatic lesions and induces keratinocyte hyperproliferation in vitro and in vivo. To determine the molecular mechanisms linking a proteolytic effect of HLE and epidermal hyperproliferation, we examined the effects of HLE-induced signaling in human keratinocytes. Application of 100 nM HLE resulted in a transient calcium influx in FURA2-loaded human HaCaT keratinocytes observed by single-cell fluorescence imaging. The calcium signal was concentration dependent and was inhibited by addition of the HLE inhibitors elafin and secretory leukocyte protease inhibitor. The calcium signal was neither inhibited by pertussis toxin, cholera, or by pre-stimulation with trypsin. Incubation with the tyrosine kinase inhibitor genistein, a protein kinase C inhibitor, as well as incubation with neutralizing EGFR antibodies abolished the HLE-induced calcium influx. The supernatants of HLE-treated keratinocytes induced a calcium signal in separately cultured keratinocytes. This could be inhibited by the addition of anti-TGF-alpha antibodies. Application of HLE-induced keratinocyte proliferation, which could be inhibited by neutralizing of anti-EGFR and anti-TGF-alpha antibodies. Herein we demonstrate that HLE induces keratinocyte proliferation by proteolytic activation of an EGFR signaling cascade involving TGF-alpha.

Circulating human neutrophils from patients with severe inflammatory disorders such as erysipelas and sepsis are specifically desensitized to complement factor C5a stimulation but not to stimulation with other stimuli like N-formyl-methionyl-leucyl-phenylalanine (FMLP), interleukin-8 (IL-8), leukotriene B4 (LTB4), or platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine). In this study, we raised the question whether factors released from polymorphonuclear leukocytes (PMNs) can specifically down-regulate C5a-dependent neutrophil functions. When neutrophils were preincubated with either neutrophil lysates or neutrophil degranulation supernatants, a complete inhibition of C5a-stimulated beta-glucuronidase release and chemotaxis could be observed, whereas FMLP-, IL-8-, LTB4- or PAF-dependent functions were not affected. Serine protease inhibitors like phenylmethylsulfonyl fluoride, antileukoprotease, or elafin abolished this effect. High-performance liquid chromatography of neutrophil degranulation supernatants revealed pronounced inhibition of C5a-dependent neutrophil functions in fractions exerting elastase or cathepsin G activity, but not in fractions exerting proteinase 3 activity. Using purified human leukocyte elastase (HLE), C5a responses like intracellular calcium influx, beta-glucuronidase release, and chemotaxis were also specifically inhibited. Our experiments show that the release of HLE or cathepsin G from neutrophils specifically down-regulates the responsiveness of neutrophils to C5a. Elastase and cathepsin G may therefore play an important role in the down-regulation of acute inflammation.

Human keratinocytes are known to express the protease-activated receptors, PAR-1 and PAR-2. Activation of PAR-1 results in increased proliferation, whereas PAR-2 activation results in decreased keratinocyte proliferation. Trypsin activates PAR-1 and in higher concentrations, PAR-2. The aim of this study was to evaluate the overall effect of trypsin on keratinocyte proliferation in a mouse in vivo and in vitro model. Daily topical application of 0.3-300 pmol trypsin/cm2 on hairless mouse skin induced dose-dependent epidermal hyperproliferation as determined by an increase in 5-bromo-2'-deoxyuridine incorporation of up to eight-fold in basal keratinocytes and an up to three-fold increase in keratinocyte layers. This was accompanied by an increased transepidermal water loss. These effects of trypsin were abolished by the addition of the trypsin inhibitor n-p-tosyl-l-lysine-chloromethyl ketone. Histological analysis revealed acanthosis, hypergranulosis, and spongiosis in the epidermis as well as vasodilatation and an inflammatory infiltrate in the upper dermis. In the murine keratinocyte cell line PAM-212 activation of PAR-1 with specific activating peptides resulted in a calcium influx and an increase of proliferation, whereas activation of PAR-2 caused a diminished proliferation. Incubation with trypsin, PAR-1-, and PAR-2-activating peptides induced cytokine-induced neutrophil chemoattractant (KC) mRNA expression as a marker for inflammation in PAM-212 in a dose-dependent manner. In conclusion, our results suggest that trypsin induces in vivo epidermal proliferation and inflammation. Proliferation seems not to be signaled by PAR activation, but PAR-2-induced KC chemokine expression may contribute in part to trypsin-induced inflammation.

Elafin is a skin-derived serine-protease inhibitor. It is thought to be important to prevent human leukocyte elastase-mediated tissue damage and might play an important role in maintaining the integrity of the human epidermis. Recent studies have provided evidence for an antimicrobial activity of elafin against P. aeruginosa. As gram-negative infections typically occur in barrier-disrupted skin we were interested to determine whether supernatants of the gram-negative bacteria P. aeruginosa and Escherichia coli were capable of inducing elafin expression. Supernatants of various P. aeruginosa strains stimulated elafin mRNA-expression and protein release, whereas supernatants of E. coli did not induce elafin expression. In non-differentiated cells the relative increase of elafin mRNA was much higher (100-fold) than in differentiated cells (sixfold), although the latter exhibited higher constitutive mRNA-expression (150-fold). However, concentrations of secreted elafin were similar in differentiated and non-differentiated cells after stimulation. We could not confirm a bactericidal effect against P. aeruginosa as described previously but observed that its growth was inhibited as demonstrated for different strains in liquid cultures. Growth of E. coli was not affected by elafin. In conclusion, the data presented in this paper suggest that elafin represents an innate immune response factor induced by secreted products of P. aeruginosa. Besides its elastase inhibitory potency elafin is an antimicrobial agent against P. aeruginosa.

Mycosis fungoides is a rare cutaneous lymphoma. Dissemination to extra-cutaneous sites occurs at advanced stages of disease. Laryngeal manifestations of mycosis fungoides have been reported in only 13 cases in the available literature. We present a further calla of mycosis fungoides of the larynx at the terminal stage of disease with an additional manifestation in the left maxillary sinus and review the cases published to date. To our knowledge this is the first reported case of mycosis fungoides with laryngeal and paranasal sinus manifestation. Concluding from the present case and from literature therapy should be palliative to improve quality of life.

Neutrophil infiltration and epidermal hyperproliferation are major histopathologic changes observed in psoriasis. Neutrophils contain human leukocyte elastase, which is thought to be released during neutrophil infiltration of the epidermis. As active human leukocyte elastase is known to be present in psoriatic lesions we were interested whether human leukocyte elastase induces hyperproliferation in keratinocytes in vitro and in vivo. In the cultured murine keratinocyte cell line PAM-212 concentrations of human leukocyte elastase from 1 to 30 nM induced significant proliferation as determined by 5-bromo-2'-deoxy-uridine-incorporation. Daily topical application of 0.043-434.8 pmol human leukocyte elastase per cm2 skin on hairless mice induced a concentration-dependent epidermal hyperproliferation and an increase in 5-bromo-2'-deoxy-uridine incorporation of up to 5-fold in basal keratinocytes within 3 d. Hyperproliferation resulted in a up to 2-fold increase of keratinocyte layers. Histologic analysis revealed marked vasodilatation but no inflammatory infiltrate. Application of porcine pancreatic elastase (3-300 pmol per cm2 skin) resulted in similar epidermal changes as observed for human leukocyte elastase. Hyperproliferative effects of human leukocyte elastase in vitro and in vivo were abolished by the addition of elastase inhibitors, such as elafin, anti-leukoprotease, and alpha1-protease inhibitor. In summary, human leukocyte elastase induces proliferation in murine keratinocytes in concentrations, which can be found on the skin surface of psoriatic lesions. These results may provide an explanation for the epidermal hyperproliferation observed in psoriasis.

Recently, several new genes have been discovered in various species which are homologous to the well-characterized human epithelial proteinase inhibitor elafin/SKALP (skin-derived anti-leukoproteinase). Because of the high degree of conservation and the similarities in genomic organization, we propose that these genes belong to a novel gene family. At the protein level, the family members are defined by: (1) an N-terminal domain consisting of a variable number of repeats with the consensus sequence Gly-Gln-Asp-Pro-Val-Lys that can act as an anchoring motif by transglutaminase cross-linking, and (2) a C-terminal four-disulphide core or whey acidic protein (WAP) domain, which harbours a functional motif involved in binding of proteinases and possibly other proteins. We have proposed the name trappin gene family as a unifying nomenclature for this group of proteins (trappin is an acronym for TRansglutaminase substrate and wAP domain containing ProteIN, and refers to its functional property of 'getting trapped' in tissues by covalent cross-linking). Analysis of the trappin family members shows extensive diversification in bovidae and suidae, whereas the number of primate trappins is probably limited. Recent biochemical and cell biological data on the human trappin family member elafin/SKALP suggest that this molecule is induced in epidermis by cellular stress. We hypothesize that trappins play an important role in the regulation of inflammation and in protection against tissue damage in stratified epithelia.

Antileukoprotease (ALP), also known as mucous protease inhibitor or secretory leukoprotease inhibitor, resembles one of the major antiproteases present in human body fluids. It is capable of preventing proteolytic degradation of extracellular matrix proteins by neutrophil-derived serine proteases. ALP was isolated from human callus and detected in supernatants of cultured human primary keratinocytes. ALP mRNA was constitutively expressed in keratinocytes and the expression was not significantly affected by TNF alpha or Interferon gamma stimulation. In microbicidal assays recombinant ALP exhibited antimicrobial activity against several human skin associated microorganisms like P. aeruginosa, S. aureus, S. epidermidis, and C. albicans, indicating that ALP may actively participate in mechanisms allowing homeostasis of bacterial and yeast colonization on human skin. Thus, ALP represents a major soluble serine protease inhibitor and antimicrobial agent expressed in human skin and seems to contribute to the high resistance of the epidermis against proteolysis and infections.

Tamol is widely used in the therapy of inflammatory dermatoses. It has pronounced astringent properties and is able to inactivate the neutrophil-derived elastase. Since plasminogen activation and release of mast cell chymase may occur in acute dermatitis, we investigated the inhibitory properties of tamol for these enzymes. Tamol proved to be a potent inhibitor of plasmin and mast cell chymase in concentrations relevant for use in dermatotherapy. The inhibition of mast cell chymase and plasmin by tamol was linear and non-competitive. The inactivation of proteolytic enzymes with the capacity to degrade extracellular-matrix proteins may be one of the major clinical effects of tamol in the treatment of acute inflammatory dermatoses.

Although intolerance reaction to analgesics are not uncommon, there is still a lack of standardized procedures to diagnose the problem. We retrospectively analyzed results of scratch tests as well as oral challenges with analgesics in order to evaluate risk and diagnostic relevance of these procedures. In 1987-1992 a total of 650 patients with supposed intolerance to drugs were tested by oral challenge. Among them were 98 patients with a positive history of intolerance to non-aspirin analgesics. In 56 patients the intolerance could be verified by oral challenge. In order of decreasing frequency, the most likely agents were propyphenazone, diclofenac, metamizole, ibuprofen, carbamazepine, indomethacin, phenazone (antipyrine), and paracetamol (acteaminophen). Oral provocation showed clear dose-response relationships. For propyphenazone, the half-effective provocation dose was the same for all symptoms (cutaneous, nasal, bronchial, anaphylactoid). Scratch testing was not of diagnostic significance. Standardized test protocols starting with low dose oral challenges are suitable and helpful in minimizing the risk of severe side effects.

The stratum corneum chymotryptic enzyme (SCCE) has been previously purified from human stratum corneum and resembles a chymotryptic serine endopeptidase involved in physiological detachment of corneocytes from human stratum corneum. From human stratum corneum two inhibitory activities of SCCE could be extracted. These were due to serine protease inhibitors already known to be present in human epidermis, antileukoprotease (secretory leukocyte protease inhibitor) and elafin (skin-derived antileukoprotease). The Inhibition of SCCE by antileukoprotease shows a hyperbolic, mixed type inhibition with an equilibrium dissociation constant of 63 n. Antileukoprotease also inhibits detachment of corneocytes from human plantar callus in vitro almost completely (>96%). In addition, elafin was shown to be a weak inhibitor for SCCE activity, and elafin significantly reduces the shedding of corneocytes. Thus, antileukoprotease, which is known to be produced by human keratinocytes, is likely to be the major physiological inhibitor of SCCE in the epidermis. It seems to be involved in the regulation of desquamation under physiological and pathophysiological conditions.

Background: Bath PUVA has been shown to be an effective alternative treatment for psoriasis with fewer systemic side effects than oral methoxsalen (8-MOP). The cost of 8-MOP and the need for a bath unit have prevented wider use of this treatment., Objective: We investigated the safety and efficacy of sheet bath PUVA by restricting the volume of the psoralen/bath water solution to 10 L with the aid of a polyethylene sheet., Methods: Fifty-eight patients with chronic plaque-type psoriasis were treated with bath PUVA in a concentration of 0.5 mg of 8-MOP per liter of water., Results: The group required a median of 17 baths (95% confidence interval [CI], 14-20) for clearance. Total UVA dose for the entire group was 26 J/cm2(95% CI, 18-47)., Conclusion: Sheet bath PUVA is safe, efficient, and easy. This regimen can significantly reduce the amount of 8-MOP required, thereby resulting in a favorable cost/benefit ratio.

Prurigo simplex subacuta is a chronic pruritic condition of unknown aetiology. The skin lesions respond to topical corticosteroids, UV-A and UV-B therapy only to a limited degree. Ten patients suffering from prurigo simplex subacuta were treated with foil bath PUVA at a concentration of 0.5 mg 8-methoxypsoralen/l. Using the foil bath method the volume of the psoralen/bath-water solution is restricted to 10 l with the aid of polyethylene foil. The group required a median of 13 (95% CI: 9-19) baths for clearance. The total UV-A dose for the whole group was 19 (95% CI:5-30) J/cm2. Bath PUVA is a safe and well-tolerated therapy in the treatment of prurigo simplex subacuta.

Recently, human leukocyte elastase has been detected in human eosinophils. Reinvestigating these findings, 2.5 pg active human leukocyte elastase (E.C. 3.4.21.37) were found per neutrophil isolated from peripheral blood, whereas the elastase activity of eosinophil preparations was linearly correlated with the content of contaminating neutrophils. Also spontaneous or stimulated release of active elastase was absent in eosinophils. By immunohistochemistry no elastase immunoreactivity could be demonstrated in human eosinophils. Therefore, we conclude that human eosinophils do not contain considerable amounts of human leukocyte elastase.

Polymorphonuclear leukocytes contain well-defined proteolytic enzymes in their azurophilic granules that can be released into tissues during inflammation, producing a localized excess of proteases that causes a protease-antiprotease imbalance with subsequent tissue destruction. The antiproteolytic compounds of the epidermis, such as the protease inhibitors elafin and antileukoprotease, are thought to counteract the proteolytic tissue damage. We investigated the urine of patients suffering from inflammatory skin conditions (e.g., erysipelas, psoriasis) for the presence of urinary antiprotease activities. Purification of elastase-inhibitory activities from pooled urine samples by cation exchange high-performance liquid chromatography and preparative and analytical reverse-phase high-performance liquid chromatography yielded two different types of inhibitors. One was a cationic, acid-stable, and elastase-specific inhibitor of M(r) 6,000 by size-exclusion high-performance liquid chromatography. N-terminal amino acid sequence analysis of the first 28 residues showed identity with elafin, an elastase-specific inhibitor recently isolated from psoriatic scales. The second anti-protease activity was due to two forms of urinary bikunin, the inhibitory subunit of inter-alpha-inhibitor. Both bikunin fragments, with M(r) 4,000 and 16,000, were identified by N-terminal amino acid sequence analysis of the first 10 residues and were characterized by an antiproteolytic profile against human leukocyte elastase, cathepsin G, and trypsin. Urinary protease inhibitors may serve as diagnostic markers of inflammatory diseases.

Balneo-phototherapy, in which salt baths are followed by UV-B irradiation, has proved successful in the treatment of psoriasis. Because of practical problems, the major one of which is the large turnover of bath solution volumes, balneotherapy has so far been limited to specialized treatment centres. With the aid of a polyethylene foil the volume of bathing solutions needed can be reduced to a total of 41 per bath. Balneotherapy using small bath solution volumes for total body treatment can now be applied as an outpatient regimen for salt bath and bath-PUVA therapy. The methods for establishing balneotherapy with restricted water volumes and the advantages of bath-PUVA over conventional oral psoralen therapy are described.

Antileukoprotease is known to be an antiproteolytic compound of mucous secretions in humans. While searching for peptide-like inhibitors of neutrophil-derived serine proteases in horny layers of human skin, we isolated a potent inhibitor of human leukocyte elastase (EC 3.4.21.37) and cathepsin G (EC 3.4.21.20) from psoriatic scales. This inhibitor showed inhibitory constants for human leukocyte elastase of approximately 0.5-2 x 10(-10) M and for cathepsin G of 2-4 x 10(-9) N. The N-terminal amino acid sequence of the purified peptide matched the sequence of antileukoprotease and both peptides showed the same M(r) on SDS-PAGE. Therefore, antileukoprotease may not only regulate serine protease activities in mucous secretions, but also in skin.

Elafin and antileukoprotease are potent peptide-like inhibitors of human leukocyte elastase and have been isolated from human skin and bronchial mucus. Elafin proved to be a potent inhibitor of proteinase 3, whereas other inhibitors of human leukocyte elastase such as antileukoprotease and eglin C proved to be much less effective.

Human leukocyte elastase (HLE) is a broad spectrum serine protease derived from neutrophils and macrophages. We developed an assay to determine HLE activity on the skin surface in patients with inflammatory skin diseases. HLE activity was absent in the skin of healthy controls. A massive increase of HLE activity was found in lesional skin of psoriasis (31 times), allergic contact dermatitis (55 times), and atopic dermatitis (35 times), but not in uninvolved skin of diseased patients. Therefore, this assay appears to represent a useful biochemical marker of epidermal inflammation. The presence of proteolytically active HLE in diseased epidermis, which is known to contain specific inhibitors of this enzyme, suggests a pathophysiologic role of this enzymatic activity in psoriasis, contact dermatitis, and atopic dermatitis.

Tannins of natural or synthetic origin are well-known adjuvants in topical anti-inflammatory therapy of skin diseases. In this study, the influence of synthetic tannin on neutrophil accumulation, enzyme release, and on the proinflammatory activity of neutrophil-derived enzymes was investigated. The results show that synthetic tannin (Tamol) specifically inhibits the neutrophil serine protease human leukocyte elastase (HLE) in an irreversible manner with a half-maximal inhibitory concentration (IC50) of 0.3 microgram/ml. Exogenous protein partially abolished the tannin-dependent HLE inhibition (IC50 of Tamol at 1% protein-concentration:1.0 microgram/ml). Synthetic tannin did not influence the activities of other neutrophil enzymes like Cathepsin G, beta-glucuronidase, and myeloperoxidase. The specificity of Tamol for HLE was further substantiated by the lack of inhibition of other serine proteases. Additionally, Tamol had no effect on f-met-leu-phe-induced neutrophil chemotaxis and did not alter enzyme degranulation of neutrophils in response to f-met-leu-phe and opsonized zymosan. We conclude from our results that the anti-inflammatory properties of synthetic tannin may at least in part be due to inactivation of the proinflammatory protease HLE.

Elafin, a human skin derived inhibitor of human leukocyte elastase, was tested for inhibitory activity against proteinase 3, an elastin degrading proteinase of neutrophils. The inhibitory activity of elafin was compared with antileukoprotease and eglin C. Elafin proved to be a potent inhibitor of elastin-FITC degradation showing an IC 50 of 9.5 x 10(-9) M. Potency was found to be more than 100-fold higher as compared with antileukoprotease and eglin C.

Human leukocyte elastase, a proteolytic enzyme of neutrophils, can be determined by a highly sensitive enzymatic assay. Bathing in hypertonic salt solutions allowed considerable amounts of human leukocyte elastase to be eluted from psoriatic lesions. Optimal elution was achieved with sodium chloride concentrations of 1 M and higher. Thirty patients with psoriasis of varying degrees of severity released significantly increased amounts of human leukocyte elastase following a 10-min bath in salt water. During daily treatment with salt water baths and UV-B radiation the elutable amounts of elastase decreased dramatically within a few days, reaching normal levels when the skin had cleared. Determination of human leukocyte elastase in salt water eluates of psoriatic skin seems to be useful for quantification of therapeutic effects. It appears conceivable that human leukocyte elastase plays a role in the psoriatic tissue reaction.