Pressor and subpressor angiotensin II administration. Two experimental models of hypertension

BACKGROUND: The neutrophil elastase inhibitor, secretory leucocyte protease inhibitor (SLPI), is a potential therapeutic tool in inflammatory lung diseases such as cystic fibrosis and pulmonary emphysema. The distribution and disappearance in the lung of aerosolised recombinant SLPI (rSLPI) was investigated in healthy humans and in patients with cystic fibrosis or alpha 1-antitrypsin-associated emphysema. METHODS: To distinguish aerosolised rSLPI from endogenous SLPI the recombinant inhibitor was radiolabelled with 99m-technetium (99mTc) pertechnetate. Distribution and disappearance of aerosolised 99mTc-rSLPI in the lungs were studied by gamma radiation imaging. RESULTS: The deposition of 99mTc-rSLPI in normal volunteers was homogeneous in all lung lobes, while in patients with cystic fibrosis or emphysema only well ventilated areas showed deposition of the aerosol. The disappearance rate of 99mTc-rSLPI was biexponential. The half life of the rapid phase was 0.2-2.8 hours, while that of the slow phase was more than 24 hours. CONCLUSIONS: Future aerosol therapy with rSLPI will be most beneficial for well ventilated lung tissue that needs protection against neutrophil derived elastase. It may be more difficult to neutralise the burden of elastase in poorly ventilated, highly inflamed areas as are seen in cystic fibrosis.     

Secretory leukoprotease inhibitor: partnering alpha 1-proteinase inhibitor to combat pulmonary inflammation

Secretory leukoprotease inhibitor (SLPI) is a low molecular weight serine proteinase inhibitor, notably of neutrophil elastase (NE), which is synthesised and secreted by the pulmonary epithelium. SLPI plays an important role in limiting NE-induced pulmonary inflammation and, significantly, it also possesses anti-HIV activity. SLPI is a significant component of the anti-NE shield in the lung which has different reactivity from, and is therefore complementary to, the anti-NE action of alpha 1-proteinase inhibitor (alpha 1-PI). Inhaled recombinant SLPI (rSLPI) could prove beneficial in partnership with alpha 1-PI in the treatment of a number of inflammatory lung disorders including emphysema, chronic bronchitis, cystic fibrosis, and adult respiratory distress syndrome.     

Metastatic choriocarcinoma presenting as multiple intracerebral haemorrhages: the role of imaging in the elucidation of the pathology

Eighteen-year-old adolescents with alpha1-antitrypsin (alpha1AT) deficiency have mostly normal lung function tests. We hypothesized that compensatory increases in other protease inhibitors and/or a decreased leukocyte activity might favorably affect the protease/protease-inhibitor balance in alpha1AT-deficient adolescents. At the age of 18 y 46 PiZZ (severe deficiency), 22 PiSZ (moderate deficiency), and 41 control subjects were studied. The plasma protease inhibitors alpha2-macroglobulin (alpha2M), alpha1-antichymotrypsin (Achy), and secretory leukocyte protease inhibitor (SLPI) were studied, and the protease elastase complexed with alpha1AT (HEAT) and neutrophil gelatinase-associated lipocalin (NGAL) as indicators of neutrophil leukocyte activity. Significantly higher concentrations of alpha2M were found in PiZ (p < 0.0001) and PiSZ (p < 0.0001) individuals compared with control subjects. The PiZZ and SZ adolescents had low levels of NGAL (p < 0.0001). Low levels of HEAT were found in PiZZ subjects (p < 0.0005). Higher concentrations of Achy were found in PiZZ (p < 0.04) and PiSZ (p < 0.05) individuals. Increased concentrations of alpha2M and Achy combined with decreased levels of HEAT and NGAL, indicating decreased leukocyte activity may, to some extent, compensate for the protease/protease inhibitor imbalance in the alpha1AT-deficiency state.     

Regulation of secretory leukocyte proteinase inhibitor (SLPI) and elastase-specific inhibitor (ESI/elafin) in human airway epithelial cells by cytokines and neutrophilic enzymes

The regulation of the activity of potentially harmful proteinases secreted by neutrophils during inflammation is important for the prevention of excessive tissue injury. Secretory leukocyte proteinase inhibitor (SLPI), also called antileukoprotease (ALP) or mucus proteinase inhibitor (MPI), is a serine proteinase inhibitor that has been found in a variety of mucous secretions and that is secreted by bronchial epithelial cells. We recently reported the presence of SLPI and of an elastase-specific inhibitor (ESI), also called elafin, in the supernatants of two cell lines, NCI-H322 and A549, which have features of Clara cells and type II alveolar cells, respectively. We showed in addition that epithelial cell lines produce the elastase-specific inhibitor as a 12 to 16 kD precursor of the elafin molecule (6 kD) called pre-elafin. In the present study, we show that NCI-H322 cells produced higher amounts of both inhibitors than A549 cells and that basal production of SLPI in both cell lines is higher than the production of elafin/pre-elafin. In addition, we show that interleukin-1 beta and tumor necrosis factor induce significant SLPI expression and are major inducers of elafin/pre-elafin expression. Moreover, induction is greater in A549 cells than in NCI-H322 cells. The implications of these findings for the peripheral airways are twofold: (1) alveolar epithelial cells may respond to cytokines secreted during the onset of inflammation by increasing their antiprotease shield; (2) elafin/pre-elafin seems to be a true local "acute phase reactant" whereas SLPI, in comparison, may be less responsive to local inflammatory mediators.     

Protective effects of an aptamer inhibitor of neutrophil elastase in lung inflammatory injury

Neutrophils play an important part in the development of acute inflammatory injury. Human neutrophils contain high levels of the serine protease elastase, which is stored in azurophilic granules and is secreted in response to inflammatory stimuli. Elastase is capable of degrading many components of extracellular matrix [1-4] and has cytotoxic effects on endothelial cells [5-7] and airway epithelial cells. Three types of endogenous protease inhibitors control the activity of neutrophil elastase, including alpha-1 protease inhibitor (alpha-1PI), alpha-2 macroglobulin and secreted leukoproteinase inhibitor (SLPI) [8-10]. A disturbed balance between neutrophil elastase and these inhibitors has been found in various acute clinical conditions (such as adult respiratory syndrome and ischemia-reperfusion injury) and in chronic diseases. We investigated the effect of NX21909, a selected oligonucleotide (aptamer) inhibitor of elastase, in an animal model of acute lung inflammatory disease [11-14]. This inhibitor was previously selected from a hybrid library of randomized DNA and a small-molecule irreversible inhibitor of elastase (a valine diphenyl ester phosphonate, Fig. 1), by the blended SELEX process [15]. We show that NX21909 inhibits lung injury and neutrophil influx in a dose-dependent manner, the first demonstration of efficacy by an aptamer in an animal disease model.     

Effect of fluticasone propionate on sputum of patients with chronic bronchitis and emphysema

The effects of fluticasone propionate (FP) on sputum chemotactic activity, elastase inhibitory potential, albumin concentrations, and peripheral neutrophil function were studied in a group of patients with clinically stable, smoking-related chronic bronchitis and emphysema. Seventeen patients (50 to 75 yr of age) were entered into a double-blind, placebo-controlled study of 1.5 mg inhaled FP/d for 8 wk. Following treatment with FP the chemotactic activity of the sputum sol phase was lower than the corresponding values for the placebo group (p < 0.01). Values fell from a mean of 21.75 (+/- 1.58) during the run-in period to 18.37 (+/- 1.46; p < 0.01) after 4 wk and 17.63 (+/- 1.86; p < 0.05) after 8 wk treatment returning to 22.08 (+/- 1.26) cell/field after the washout period. The neutrophil elastase inhibitory capacity of the sputum sol phase increased (p < 0.025) with treatment from a mean of 0.177 microM elastase inhibited/L (+/- 0.05) pretreatment to 0.413 microM (+/- 0.054) after 4 wk and 0.415 microM (+/- 0.054) after 8 wk returning to 0.270 microM (+/- 0.07) after the washout period. Treatment with FP did not result in a change in the peripheral neutrophil functions studied or sputum albumin and myeloperoxidase concentrations. The results suggest that FP may play a protective role in these patients through a reduction in the chemotactic activity of lung secretions and potentially a reduction in the recruitment of neutrophils to the lung, and also by directly affecting the proteinase/antiproteinase balance, in favor of antiproteinases, within lung secretions.     

Host response to initial and challenge infections, following treatment, of Gyrodactylus bullatarudis and G. turnbulli (Monogenea) on the guppy (Poecilia reticulata)

Patients homozygous for the Z allele of alpha-1-antitrypsin (alpha 1AT) have very low serum levels and are predisposed to emphysema. There have also been reports of emphysema being associated with the heterozygous phenotype FZ. To investigate whether F alpha 1AT was dysfunctional, the inhibitory activity of F alpha 1AT against human neutrophil elastase (HNE) was compared with that of common alpha 1AT phenotypes. Time-dependent inhibition of HNE by alpha 1AT was used to calculate the association rate constant (k assoc) for M, MZ, FM, FZ, F (partially purified from FZ or FS), Z and S alpha 1AT phenotypes in human sera. The results for k assoc at 25 degrees C were 9.1 (SD 0.9), 9.7 (SD 0.9), 8.0 (SD 0.8), 4.0 (SD 0.4), 4.2 (SD 0.8), 5.1 (SD 0.6) and 8.6 (SD 0.6) x 10(6) M-1s-1 respectively. F was found to have reduced activity much like that of Z, the alpha 1AT most commonly associated with emphysema. MZ (low risk for disease) and FZ heterozygotes had similar intermediate alpha 1AT levels. However the in vivo inhibition time for FZ was almost three times longer than for MZ, indicating greater exposure to proteolytic damage from free elastase for FZ than MZ individuals. In conclusion, F alpha 1AT is expressed in serum at low normal levels but is dysfunctional in its ability to inhibit HNE. Individuals who coinherit the F and a deficiency allele such as Z or Null, are likely to have a high risk for the development of emphysema. The disease risk for F homozygotes remains to be determined.     

Oncostatin M, but not interleukin-6 or leukemia inhibitory factor, stimulates expression of alpha1-proteinase inhibitor in A549 human alveolar epithelial cells

Alpha-1 proteinase inhibitor (A1-Pi) is the main serine proteinase inhibitor found in human plasma and is a potent elastase inhibitor in various tissues, including lung. A1-Pi is expressed and induced in liver during inflammatory responses but can also be produced by epithelial cells. Since hepatocyte A1-Pi production is stimulated by interleukin-6 (IL-6) and other gp130-cytokines, such as leukemia inhibitory factor (LIF) and oncostatin M (OM), we investigated the role of these cytokines in regulating A1-Pi in lung epithelial cells. We show that OM, a monocyte and T cell product, can specifically and potently induce A1-Pi production in lung-derived A549 alveolar (epithelial) cells, as well as in liver-derived HepG2 cells. Both A1-Pi protein (as detected by ELISA and Western blots) and mRNA levels were enhanced 20-fold to 30-fold in A549 cells. OM was also able to stimulate the expression of tissue inhibitor of metalloproteinase-1 in these cells. Interestingly, other members of the IL-6 family (IL-6 and LIF) had little or no effect on A549 cells, and proinflammatory cytokines, such as IL-1 beta and tumor necrosis factor-alpha (TNF-alpha) also had no stimulatory effect on A1-Pi synthesis in A549 cells. Costimulation with IL-1 beta resulted in a decrease in A1-Pi production from OM-stimulated A549 cells. However, IL-6 production was synergistically enhanced. OM was also able to stimulate A1-Pi production from a bronchial epithelial primary cell line, whereas an intestinal epithelial cell line HT29 responded to IL-6 but not OM. These results suggest that lung levels A1-Pi could be derived not only from liver and inflammatory cells but also from epithelial cells, which can be upregulated on stimulation by OM. This may have implications for regulation of local activity of human neutrophil elastase (HNE) in such diseases as emphysema and cystic fibrosis.     

Neutrophil serine proteinases and defensins in chronic obstructive pulmonary disease: effects on pulmonary epithelium

Neutrophils have the capacity to accumulate in high numbers in the lung during infection and inflammation. Because they play an important role in host defence against infection, but may also cause tissue injury, these cells are thought to be involved in the pathogenesis of various inflammatory lung disorders, including chronic bronchitis and chronic obstructive pulmonary disease. Neutrophil products that may mediate tissue injury at sites of neutrophil-dominated inflammation include the neutrophil serine proteinases elastase, cathepsin G and proteinase 3, and the nonenzymatic defensins. One of the targets of the neutrophil is the lung epithelium, and in vitro studies have revealed that both the serine proteinases and neutrophil defensins markedly affect the integrity of the epithelial layer, decrease the frequency of ciliary beat, increase the secretion of mucus, and induce the synthesis of epithelium-derived mediators that may influence the amplification and resolution of neutrophil-dominated inflammation. Both neutrophil elastase and defensins induce the release of the neutrophil chemoattractant chemokine interleukin-8 from respiratory epithelial cells. The alpha1-proteinase inhibitor (alpha1-PI) is a well-characterized inhibitor of neutrophil elastase, that also blocks the cytotoxic and stimulatory activity of defensins towards epithelial cells. The elastase inhibitory activity of alpha1-PI is also abrogated by the binding of defensins to this inhibitor. Incubation of epithelial cells with neutrophil defensins in combination with either elastase or cathepsin G resulted in decreased effects on the epithelial cells compared with those observed when the cells were incubated with defensins, elastase or cathepsin G separately. These results suggest that neutrophil defensins and serine proteinases cause injury and stimulate epithelial cells to produce chemokines that attract more neutrophils to the site of inflammation. The effects of neutrophil defensins and serine proteinases on epithelial cells appear to be restricted by proteinase inhibitors and by inhibitory interactions between these sets of neutrophil granule proteins.     

Inhibition of murine neutrophil serine proteinases by human and murine secretory leukocyte protease inhibitor

Human secretory leukocyte protease inhibitor (SLPI) is a predominant physiologic inhibitor of elastase and cathepsin G, proinflammatory serine proteases released by activated neutrophils. In order to fully evaluate the potential pharmacologic efficacy of human SLPI in animal models of inflammation, it is critical to know the potency of the inhibitor for corresponding proteases from the species of interest. In this report, we compare the inhibitory activity of human and murine SLPI against elastase and cathepsin G from both species. Human and murine neutrophil elastase and cathepsin G display comparable Km values for their specific peptide substrates. Murine SLPI inhibits murine neutrophil elastase and cathepsin G with Ki values of 5 and 0.12 nM, respectively, while human SLPI inhibits the both murine serine proteases with Ki's of 0.02 nM. In contrast, murine SLPI inhibits human neutrophil elastase and cathepsin G with Ki values of 1.4 and 90 nM, respectively, while human SLPI inhibits the proteases with Ki's of 0.3 and 10 nM, respectively. These results demonstrate species-specific variations in the protease inhibitory activities of SLPI. Such variations should be considered in the evaluation of the activity of human SLPI in murine pharmacologic models.     

Mechanism-based inhibitors of serine proteinases based on the Gabriel-Colman rearrangement

Neutrophil-derived mediators such as, for example, the serine proteinase elastase, cathepsin G and proteinase 3, play a critical role in inflammatory lung disease. This report describes the design, synthesis and in vitro inhibitory activity of some novel mechanism-based inhibitors of human leukocyte elastase and cathepsin G. The design of the inhibitors is based on the Gabriel-Colman rearrangement. The behavior of the synthesized compounds toward elastase and cathepsin G with respect to inhibitory prowess, mode of interaction, specificity, etc., has been found to be dependent on the recognition and reactivity elements present in each inhibitor.     

Highly potent irreversible inhibitors of neutrophil elastase generated by selection from a randomized DNA-valine phosphonate library

We incorporated a phosphonate irreversible inhibitor of neutrophil elastase into a randomized DNA library and, using the SELEX process, iteratively selected these assemblies for the most potent elastase inhibitors. The inhibitors were selected against purified elastase and against secreted elastase in the presence of activated neutrophils. Very active aptamer inhibitors were obtained by both methods, with second-order rate constants for inactivation of human neutrophil elastase ranging (1-3) x 10(8) M(-1) min(-1). These rates exceed those of any reported irreversible inhibitor of elastase and exceed the previous best phosphonate inhibitors by 80-fold. The selected inhibitors are also significantly more potent than alpha-1 proteinase inhibitor in blocking degradation of elastin by activated neutrophils. In contrast to a previous experiment [Smith et al. (1995) Chem. Biol. 2, 741-750], a single-enantiomer form of the valyl phosphonate was used rather than a racemic mixture. Our analysis shows that this use of a chirally resolved valyl phosphonate results in selection of much more potent inhibitors and that these inhibitors specifically potentiate a single enantiomeric form of the phosphonate.     

Alpha-1-antitrypsin PLowell: a normally functioning variant present in low concentration

BACKGROUND: Alpha-1-antitrypsin deficiency is associated with a high risk for the development of emphysema, particularly for phenotype Pi ZZ, which is both deficient and an abnormal inhibitor of the powerful proteolytic enzyme, human neutrophil elastase. The rare variant PLowell is also expressed at abnormally low levels, but its anti-elastase activity has not been described. AIM: To study the anti-elastase activity of alpha-1-antitrypsin PLowell and compare it to the common M, S and Z proteins. METHOD: Alpha-1-antitrypsin from a female patient aged 75 years with the rare genotype PLowell NullBellingham was studied for its ability to inhibit human neutrophil elastase in a time dependent manner. RESULTS: PLowell has near normal function as an inhibitor of human neutrophil elastase with an association rate constant of 7.4 x 10(6) M-1 S-1 at 25 degrees C, similar to that of M and S. CONCLUSION: Alpha-1-antitrypsin PLowell is associated with a severe deficiency of alpha-1-antitrypsin similar to Z, but unlike that protein it has near normal function as an anti-elastase.     

Treatment of subdural effusion with hydrocephalus after ruptured intracranial aneurysm clipping

This study examined the role of cysteine proteinases and their inhibitor in the development of emphysema in comparison with neutrophil elastase (NE) complexed with alpha1-protease inhibitor (NE-alpha1-PI), which was previously demonstrated to be increased in bronchoalveolar lavage (BAL) fluid from subjects with subclinical emphysema. Eight nonsmokers and 31 current smokers with (n=17) and without (n=14) emphysema, as evidenced by lung computed tomographic scans, were studied. The concentrations of immunologically detected cathepsin L and cystatin C, but not cathepsin B, were significantly increased in BAL fluid from the smokers with emphysema compared with those without emphysema, although the activity of cathepsin L, measured using a synthetic substrate and cathepsin L, released from cultured alveolar macrophages at 24 h, did not show any significant difference between the two groups. When comparison was made only for the subjects aged <60 yrs, the difference between the two groups disappeared for cathepsin L, but remained for NE-alpha1-PI. There was no significant correlation between the level of cathepsin L and that of NE-alpha1-PI in BAL fluid from the subjects with emphysema. In conclusion, increased levels of cathepsin L and cystatin C were demonstrated in bronchoalveolar lavage fluid from subjects with subclinical emphysema. However, the roles of cathepsin L and neutrophil elastase in the development of emphysema may vary between subjects and between the young and the old.     

Long-term therapy of alpha 1-antitrypsin-deficiency-associated pulmonary emphysema with human alpha 1-antitrypsin

alpha 1-antitrypsin (alpha 1-AT) deficiency is a genetic disorder characterized by low serum levels of alpha 1-AT and a high risk of pulmonary emphysema at a young age. The resulting surplus of proteases, mainly of neutrophil elastase, can be balanced by i.v. augmentation with alpha 1-AT. However, it is not clear if affected patients benefit from long-term augmentation therapy and no long-term safety data are available. We examined 443 patients with severe alpha 1-AT deficiency and pulmonary emphysema receiving weekly i.v. infusions of 60 mg/kg body weight alpha 1-AT in addition to their regular medication. The progression of the disease was assessed by repeated lung function measurements, particularly the decline in forced expiratory volume in 1 second (delta FEV1). 443 patients with alpha 1-AT deficiency tolerated augmentation therapy well with few adverse reactions. The delta FEV1 in 287 patients with available follow-up data was 57.1 +/- 31.1 ml per year. Stratified for baseline FEV1, the decline was 35.6 +/- 21.3 ml in the 108 patients with an initial FEV1 < 30% and 64.0 +/- 26.4 ml in the 164 with 30% < FEV1 < or = 65% of predicted normal (p = 0.0008). The remaining 15 patients had an initial FEV1 > 65%. Long-term treatment with i.v. alpha 1-antitrypsin in patients with severe alpha 1-Pi deficiency is feasible and safe. The decline in forced expiratory volume in one second is related to the initial forced expiratory volume in one second as in alpha 1-antitrypsin deficient patients not receiving augmentation therapy.     

Effect of polynucleotides on the inhibition of neutrophil elastase by mucus proteinase inhibitor and alpha 1-proteinase inhibitor

DNA released from neutrophils at sites of inflammation may modulate tissue proteolysis. We used tRNA and synthetic polynucleotides as models of DNA to study the influence of polynucleotides on the inhibition of neutrophil elastase by its endogenous inhibitors alpha1-proteinase inhibitor (alpha1-PI) and mucus proteinase inhibitor (MPI). Affinity chromatography showed that polynucleotides form electrostatic complexes with elastase and MPI but not with alpha1-PI, the highest affinity being for MPI. The tight-binding partial inhibition of elastase by polynucleotides was used to calculate the Kd of the elastase-polynucleotide complexes which ranged from 4 microM to 21 nM. One mole of tRNA was able to bind 9 mol of elastase. Polydeoxycytosine and tRNA significantly impaired the reversible inhibition of elastase by MPI: they moderately increased the rate of enzyme-inhibitor association, strongly enhanced the rate of complex dissociation, and lowered the enzyme-inhibitor affinity by factors of 34 and 134, respectively. The two polynucleotides also decreased the rate of the irreversible inhibition of elastase by alpha1-PI by factors of 30 and 3, respectively. Polynucleotides also changed the mechanism of inhibition of elastase by the two inhibitors from a one-step inhibition reaction to a two-step binding mechanism. Our data may help explain why proteolysis may occur at sites of inflammation despite the presence of active proteinase inhibitors.     

Drug-induced lupus erythematosus

alpha 1-Antitrypsin (AT) is the principal serum inhibitor of proteolytic enzymes such as neutrophil elastase. AT can exist as over 90 different genetically determined variants known as the Pi system; the three most important variants are type M (90% of population) and types S and Z, two of the commoner abnormal variants. Homozygotes of type Z have a severe reduction in the serum AT concentration and may develop pulmonary emphysema or hepatic cirrhosis. Heterozygotes of type SZ have a less severe reduction in serum AT concentration and the association with clinical disease is less clear. The S and Z variants are found mainly among those of European stock. The gene frequency for Pi type Z is highest on the north-western seaboard of the continent and the mutation seems likely to have arisen in southern Scandinavia. The distribution of type S is quite different; the gene frequency is highest in the Iberian peninsula and the mutation is likely to have arisen in that region. A population survey for determining the number of type Z homozygotes in a given community is important for planning purposes now that AT replacement therapy is potentially available.     

Human lysosomal elastase. Catalytic and immunological properties

1. The elastase of human spleen was shown to exhibit endopeptidase activity against azo-casein and elastin. 2. Activity against several synthetic substrates was detected, and benzyloxycarbonyl-L-alanine 2-naphthyl ester was found to be a good substrate for routine use. 3. The enzyme showed a broad pH optimum in the range of 8.2-9.2 against azo-casein and the synthetic substrate. 4. The effect of inhibitors on the spleen elastase showed it to be a serine proteinase with a specificity similar to that of porcine pancreatic elastase. 5. Specific antisera were raised against the enzyme, and it was shown to be immunologically identical with the lysosomal elastase of human neutrophil leucocytes.     

Constitutive and inducible expression of SKALP/elafin provides anti-elastase defense in human epithelia

Skin-derived antileukoproteinase (SKALP), also known as elafin, is a serine proteinase inhibitor first discovered in keratinocytes from hyperproliferative human epidermis. In addition to the proteinase inhibiting domain which is directed against polymorphonuclear leukocyte (PMN) derived enzymes such as elastase and proteinase 3, SKALP contains multiple transglutaminase (TGase) substrate domains which enable crosslinking to extracellular and cell envelope proteins. Here we show that SKALP is constitutively expressed in several epithelia that are continuously subjected to inflammatory stimuli, such as the oral cavity and the vagina where it co-localizes with type 1 TGase. All epithelia from sterile body cavities are negative for SKALP. In general, stratified squamous epithelia are positive, whereas pseudostratified epithelia, simple/glandular epithelia and normal epidermis are negative. SKALP was found in fetal tissues of the oral cavity from 17 wk gestation onwards where it continued to be expressed up to adult life. Remarkably, in fetal epidermis SKALP was found from week 28 onwards, but was downregulated to undetectable levels in neonatal skin within three months, suggesting a role during pregnancy in feto-maternal interactions or in the early maturation phase of the epidermis. Immunoelectron microscopy revealed the presence of SKALP in secretory vesicles including the lamellar granules. In culture models for epidermal keratinocytes we found that expression of the endogenous SKALP gene provided protection against cell detachment caused by purified elastase or activated PMNs. Addition of exogenous recombinant SKALP fully protected the keratinocytes against PMN-dependent detachment whereas superoxide dismutase and catalase were only marginally effective. These findings strongly suggest that the constitutive expression of SKALP in squamous epithelia, and the inducible expression in epidermis participate in the control of epithelial integrity, by inhibiting PMN derived proteinases.