Serum secretory leukoprotease inhibitor levels to diagnose pneumonia in the elderly

A novel in vitro cell model of the proteinase/antiproteinase balance observed in alpha-1 antitrypsin deficiency

Background: Alpha-1 antitrypsin deficiency (AATD) is a genetic condition resulting from mutations in the alpha-1 antitrypsin (AAT) protein, a major systemic antiproteinase, resulting in reduced/no release of AAT, disrupting the proteinase/antiproteinase balance. A sustained imbalance can cause structural changes to the lung parenchyma, leading to emphysema. Predicting and assessing human responses to potential therapeutic candidates from preclinical animal studies have been challenging. Our aims were to develop a more physiologically relevant in vitro model of the proteinase/antiproteinase balance and assess whether the data generated could better predict the efficacy of pharmacological candidates to inform decisions on clinical trials, together with expected biomarker responses. Methods: We developed an in vitro model assessing the proteinase/antiproteinase balance by the changes in the fibrinogen cleavage products of neutrophil elastase (NE) and proteinase 3 (PR3). This allowed the assessment of physiological and pharmaceutical neutrophil serine proteinase (NSP) inhibitors to determine the putative threshold at which the maximal effect is achieved. Results: AAT significantly reduced NE and PR3 activity footprints, with the maximal reduction achieved at concentrations above 10 μM. The inhibitor MPH966 alone also significantly reduced NE footprint generation in a concentration-dependent manner, leveling out above 100 nM but had no effect on the PR3 footprint. At levels of AAT consistent with AATD, MPH966 had an additive effect, reducing the NE activity footprint more than either inhibitor alone. Conclusion: Our results support an inhibitor threshold above which the activity footprint generation appears resistant to increasing dosage. Our model can support the testing of inhibitors, confirming activity biomarkers as indicators of likely pharmaceutical efficacy, the assessment of NSP activity in the pathophysiology of emphysema, and the likely function of biological or pharmacological inhibitors in disease management.

The Alpha-Tocopherol Form of Vitamin E Boosts Elastase Activity of Human PMNs and Their Ability to Kill Streptococcus pneumoniae

Despite the availability of vaccines, Streptococcus pneumoniae remains a leading cause of life-threatening infections, such as pneumonia, bacteremia and meningitis. Polymorphonuclear leukocytes (PMNs) are a key determinant of disease course, because optimal host defense requires an initial robust pulmonary PMN response to control bacterial numbers followed by modulation of this response later in infection. The elderly, who manifest a general decline in immune function and higher basal levels of inflammation, are at increased risk of developing pneumococcal pneumonia. Using an aged mouse infection model, we previously showed that oral supplementation with the alpha-tocopherol form of vitamin E (α-Toc) decreases pulmonary inflammation, in part by modulating neutrophil migration across lung epithelium into alveolar spaces, and reverses the age-associated decline in resistance to pneumococcal pneumonia. The objective of this study was to test the effect of α-Toc on the ability of neutrophils isolated from young (22–35 years) or elderly (65–69 years) individuals to migrate across epithelial cell monolayers in response to S. pneumoniae and to kill complement-opsonized pneumococci. We found that basal levels of pneumococcal-induced transepithelial migration by PMNs from young or elderly donors were indistinguishable, suggesting that the age-associated exacerbation of pulmonary inflammation is not due to intrinsic properties of PMNs of elderly individuals but rather may reflect the inflammatory milieu of the aged lung. Consistent with its anti-inflammatory activity, α-Toc treatment diminished PMN migration regardless of donor age. Unexpectedly, unlike previous studies showing poor killing of antibody-opsonized bacteria, we found that PMNs of elderly donors were more efficient at killing complement-opsonized bacteria ex vivo than their younger counterparts. We also found that the heightened antimicrobial activity in PMNs from older donors correlated with increased activity of neutrophil elastase, a serine protease that is required to kill pneumococci. Notably, incubation with α-Toc increased PMN elastase activity from young donors and boosted their ability to kill complement-opsonized pneumococci. These findings demonstrate that α-Toc is a potent modulator of PMN responses and is a potential nutritional intervention to combat pneumococcal infection.

Clinical significance of serum levels of secretory leukocyte protease inhibitor in patients with systemic sclerosis

We aimed to investigate the clinical significance of serum levels of secretory leukocyte protease inhibitor (SLPI), which is widely expressed in lung tissues and serves as a useful marker reflecting the activity of various lung diseases, in patients with systemic sclerosis (SSc). Serum SLPI levels were measured by a specific enzyme-linked immunosorbent assay (ELISA) in 58 SSc patients and 16 healthy controls. Serum SLPI levels in diffuse cutaneous SSc and in limited cutaneous SSc with interstitial lung disease (ILD) were significantly higher than those in healthy controls (43.1 ± 18.4 vs. 30.9 ± 3.76 ng/ml, p < 0.05 and 39.8 ± 10.3 vs. 30.9 ± 3.76 ng/ml, p < 0.01, respectively). The incidences of decreased percent diffusing capacity for carbon monoxide (%DLco) and decreased percent vital capacity (%VC) were significantly greater in SSc patients with elevated SLPI levels than in those with normal levels (73 vs. 31%, p < 0.01 and 24 vs. 4%, p < 0.05, respectively). Furthermore, serum SLPI levels were inversely correlated with %DLco (r = -0.40, p < 0.01), while they were positively correlated with surfactant protein D (r = 0.28, p < 0.05). Longitudinal study revealed the association of serum SLPI levels with the disease activity of SSc-ILD. SLPI serves as a useful serum marker for evaluating SSc-ILD.

Secretory leukocyte protease inhibitor levels in cervicovaginal secretion of elderly women

OBJECTIVE

Secretory leukocyte protease inhibitor (SLPI) is a potent inhibitor of human leukocyte elastase. The aim of the present study was to examine whether there is an association between the SLPI concentration in the cervicovaginal secretion (CS) and vaginal complaints of post-menopausal women.

METHODS

Uterine cervix tissues and CS of peri- or post-menopausal women were obtained. SLPI was assayed by ELISA. To determine the level of SLPI mRNA and the localization of SLPI protein in the uterine cervix, we performed RT-PCR and immunochemical staining, respectively.

RESULTS

The levels of SLPI in the CS of post-menopausal women with vaginal complaints were significantly lower that those of post-menopausal women without vaginal complaints. The levels of SLPI in the CS of post-menopausal women were lower that those of peri-menopausal women and post-menopausal women treated with hormone replacement therapy. Positive staining was observed in epithelial cells of the cervix of elderly women, however, the intensity was weaker than that in peri-menopausal women. Positive staining was also observed in gland cells of the cervix of peri-menopausal women, but not in those of post-menopausal women. SLPI transcripts were detected in the cervix of post-menopausal women. The treatment of post-menopausal women with vaginal estrogen increased the concentrations of SLPI in CS of post-menopausal women.

CONCLUSIONS

The present findings suggest that the decreased amount of SLPI in the CS of post-menopausal women might be one of the causes of the symptoms of post-menopausal women and contribute to the immunodefense mechanisms of the elderly women.

Suppression of macrophage responses to bacterial lipopolysaccharide (LPS) by secretory leukocyte protease inhibitor (SLPI) is independent of its anti-protease function

Secretory leukocyte protease inhibitor (SLPI), a potent serine protease inhibitor, has been shown to suppress macrophage responses to bacterial lipopolysaccharide (LPS). SLPI contains two topologically superimposable domains. Its C-terminal domain binds and inhibits target proteases. It is not clear whether SLPI's anti-protease function plays a role in the LPS-inhibitory action of SLPI. Four single amino acid substitution mutants of SLPI, M73G, M73F, M73E and M73K, were generated. Wild type SLPI is a potent inhibitor of chymotrypsin and elastase. Mutants M73G and M73F selectively lost inhibitory function towards chymotrypsin and elastase, respectively, whereas mutants M73K and M73E inhibited neither elastase nor chymotrypsin. Macrophage cell lines were established from RAW264.7 cells to stably express each SLPI mutant. Expression of the SLPI protease inhibition mutants suppressed NO and TNF production in response to LPS in a similar fashion as wild type SLPI. Expression of truncated forms of SLPI, containing only its N-terminus or its C-terminus, was similarly sufficient to confer inhibition of LPS responses. Thus, the LPS-inhibitory action of SLPI is independent of its anti-protease function.

Differential proteolytic enzyme activity in eosinophilic and neutrophilic asthma

RATIONALE

Asthma is characterized by both chronic inflammation and remodeling of the airways. Proteases are important mediators of inflammation, cytokine activation, and tissue remodeling.

OBJECTIVES

This study investigated matrix metalloproteinase-9 (MMP-9) and neutrophil elastase (NE) enzyme activity in the sputum of subjects with different inflammatory phenotypes of asthma (eosinophilic, neutrophilic, and paucigranulocytic asthma) and in healthy control subjects.

METHODS AND MEASUREMENTS

Nonsmoking adults with asthma and healthy control subjects underwent hypertonic saline challenge and sputum induction. Selected sputum portions were dispersed with dithiothreitol and assayed for MMP-9 and NE enzyme activity.

MAIN RESULTS

Subjects with eosinophilic asthma had significantly more active MMP-9 (39 ng/ml) compared with those with neutrophilic asthma (10 ng/ml) and control subjects (2.5 ng/ml, p < 0.01). Although there were high levels of total MMP-9 in neutrophilic asthma (5,273 ng/ml), most (> 99%) was inactivated (and bound to tissue inhibitor of metalloproteinase-1). In neutrophilic asthma, more subjects had NE activity (39%) compared with both healthy control subjects (0%), subjects with eosinophilic asthma (6%), or subjects with paucigranulocytic asthma (0%, p < 0.05). There were strong and consistent positive correlations between interleukin-8, neutrophils, and proteolytic enzymes. MMP-9 was inversely correlated with NE (r = -0.93).

CONCLUSIONS

Proteolytic enzyme activity in asthma is dependent on the underlying inflammatory phenotype and is differentially regulated with MMP-9 activity a feature of eosinophilic inflammation, and active NE in neutrophilic inflammation.

Plasma secretory leukocyte protease inhibitor in febrile patients

OBJECTIVES

Secretory leukocyte protease inhibitor (SLPI) forms an integral part of the lung's defence, by its antimicrobial activity and by its ability to neutralize serine proteases that are released by granulocytes into the inflammatory exudate. Here, we investigate in febrile patients admitted to hospital whether plasma SLPI can serve as a marker of lung infection.

METHODS

We prospectively determined the SLPI concentration in 152 febrile patients (median 73 [inter-quantile range (IQR): 58-82] year; 50% male) admitted to hospital because of infection of the airways (n = 44) or pneumonia (n = 108; i.e. consolidation on chest X-ray), and in 48 febrile patients (78 [IQR: 71-85] year; 52% male) admitted because of pyelonephritis, as well as afebrile age-matched controls (n = 38). In addition, erythrocyte sedimentation rate (ESR), peripheral blood leukocytes, plasma TNFalpha and IL-10, and parameters of the APACHE-II score were determined on admission.

RESULTS

In febrile patients, SLPI was significantly increased (P < 0.001) compared with afebrile controls (63 [IQR: 50-76] ng/mL): plasma SLPI (113 [IQR: 83-176] ng/mL) was highest (P < 0.005) in patients with pneumonia compared with other groups (88 [IQR: 70-118] ng/mL). Only in patients with pneumonia, bacteremia significantly increased (P < 0.01) SLPI concentrations. Using a radiological classification of pulmonary infiltrates based on their size, it was found that plasma SLPI was proportional to the extent of lung tissue involved: the median concentration increased from 95 [IQR: 74-139] ng/mL in unilateral segmental consolidation up to 271 [IQR: 180-460] ng/mL in bilateral lobar consolidations. In a multivariate analysis, the association between SLPI and extent of consolidation was about two-fold stronger than, and independent of, the association between SLPI and erythrocyte sedimentation rate, TNFalpha, and parameters of the composite APACHE-II score, such as heart rate and blood pressure, that reflect severity of illness.

CONCLUSION

SLPI is an indicator of the presence and extent of pneumonia in febrile patients admitted to hospital. In patients with an infection with its primary source located outside the lung, plasma SLPI likely reflects the mucosal response to circulating inflammatory mediators reflecting severity of illness.

Secretory leukocyte protease inhibitor in punch biopsies from human colonic mucosa

Secretory leukocyte protease inhibitor (SLPI) is a well-known protease inhibitor. Its function is thought to be protease/protease-inhibitor balance. Free proteolytic activity, mainly pancreatic elastase, anionic trypsin and granulocytic elastase, has been demonstrated in faecal extracts from patients with ulcerative colitis. We wanted to verify that SLPI is actually secreted from normal human colonic mucosa. Also, we wanted to ascertain whether studies of SLPI secretion based on punch biopsies were dependent on biopsy area or on biopsy circumference. Normal colonic mucosa was sampled during surgery for colonic cancer. A total of 36 samples from four patients were used. Mucosa preparation was carried out using a punch biopsy technique, and samples of 3, 4 and 6 mm diameter were used. All media contained SLPI at varying concentrations. When expressed in terms of the sample area, the secretion per millimetre-squared seemed to decrease with increasing area. When calculated as secretion per circumference, secretion seemed to be constant. In conclusion, SLPI was secreted from normal human colonic mucosa. The SLPI secretion seemed dependent on the circumference of the biopsy rather than on the area of the biopsy.

Secretion and gene expression of secretory leukocyte protease inhibitor by human airway submucosal glands

Submucosal glands were isolated within 4 h of death from tracheae and bronchi obtained from autopsied lungs, and the secretory response of secretory leukocyte protease inhibitor (SLPI) was examined with ELISA and a secretory index. Although human neutrophil elastase (HNE) at low concentrations increased SLPI secretion above the control level (i.e., 149% of control level at 10(-11) M), HNE at high concentrations significantly decreased it below the control level (i.e., 16% of control level at 10(-7) M). The decrease in SLPI concentration was shown to result from the degradation of SLPI by excessive HNE. Methacholine induced significant secretion (i.e., 363% of control level at 10(-5) M) that was abolished by both M(1) and M(3) receptor antagonists. A semiquantitative analysis of SLPI mRNA by RT-PCR and Southern blot showed that compared with the superficial epithelium, submucosal glands had a 30-fold or higher level of SLPI mRNA. Both HNE and methacholine significantly increased the level of SLPI mRNA in submucosal glands in a dose-dependent manner (i.e., 357% of control level at 10(-7) M and 175% of control level at 10(-5) M, respectively). These findings indicate that human airway submucosal glands can transcribe 30-fold or more SLPI mRNA than the superficial epithelium and that SLPI mRNA transcription and secretion are regulated by both HNE and muscarinic receptors.

Differential diagnosis between community-acquired pneumonia and non-pneumonia diseases of the chest in the emergency ward

Background: The differential diagnosis of community-acquired pneumonia and some non-pneumonia diseases involving the chest may sometimes be cumbersome. Adding some objective variables to the diagnostic strategy may be helpful.We evaluated the main objective variables that are usually available in the emergency ward and that may be valuable in this differential diagnosis. Methods: We recorded epidemiological, clinical, and analytical data, as well as that obtained from physical examination, from 284 consecutive patients diagnosed in the emergency ward as having community-acquired pneumonia. The diagnosis was reviewed by the investigators applying pre-set diagnostic criteria. Statistical analysis was then performed comparing data from patients with a definitive diagnosis of community-acquired pneumonia with those with a final diagnosis of non-pneumonia disease excluding acute exacerbations of chronic bronchitis. Results: In the univariate analysis, C-reactive protein (difference of means 93 mg/l; 95% C.I. 47, 140), erythrocyte sedimentation rate (d.m. 19 mm/h; 95% C.I. 3, 35), leukocyte count (d.m. 3.5x10(9)/l; 95% C.I. 0.5, 6.4), and temperature (d.m. 0.5 degrees C; 95% C.I. 0.1, 0.9) discriminated between community-acquired pneumonia and non-pneumonia diseases. In the multivariate analysis, only C-reactive protein remained in the equation. Conclusions: C-reactive protein, erythrocyte sedimentation rate, leukocyte count, and temperature were measurable variables that proved to be useful in the differential diagnosis between community-acquired pneumonia and non-pneumonia diseases. C-reactive protein appears to be the most suitable for this purpose.

Levels of vaginal secretory leukocyte protease inhibitor are decreased in women with lower reproductive tract infections

OBJECTIVE

Secretory leukocyte protease inhibitor contributes resistance to primary human immunodeficiency virus infection in the oral cavity. However, the levels of this inhibitor in the genital tract of women with sexually transmitted diseases or vaginitis are not well described. The objective was to determine vaginal inhibitor levels in women with symptomatic and asymptomatic genital infections.

STUDY DESIGN

We tested 207 nonpregnant women for Neisseria gonorrhoeae, Trichomonas vaginalis, Chlamydia trachomatis, Candida species, and bacterial vaginosis by standard methods. A second group of symptom-free pregnant women (N = 231) was also studied. Secretory leukocyte protease inhibitor was measured by enzyme-linked immunosorbent assay, and results were compared by nonparametric methods.

RESULTS

Vaginal levels of secretory leukocyte protease inhibitor in both groups were significantly lower in women with any sexually transmitted disease than in those without infection (P<.0001). Patients with bacterial vaginosis and those with bacterial vaginosis with yeast vaginitis also had decreased levels (P<.025).

CONCLUSIONS

Levels of secretory leukocyte protease inhibitor in vaginal fluid are decreased in women with lower genital tract infection. This may represent a common mechanism of increasing susceptibility to infection with human immunodeficiency virus.

Increased secretory leukoprotease inhibitor in patients with nonsmall cell lung carcinoma

BACKGROUND

It is well known that acute pulmonary inflammation, such as that observed in pneumonia, elevates secretory leukoprotease inhibitor (SLPI) levels in serum. A previous report indicated that serum SLPI levels in lung carcinoma patients with concurrent pneumonia were significantly higher than in those in patients whose disease was unaccompanied by pneumonia or in healthy subjects. The authors hypothesized that serum SLPI may increase in patients with lung carcinoma, even carcinoma occurring without pneumonia, and that cells in lung carcinoma might produce SLPI.

METHODS

Serum SLPI levels in 58 patients with primary lung carcinoma unaccompanied by pneumonia and in 42 healthy subjects were measured by an enzyme immunoassay. Twenty-four specimens from 24 of the patients with primary lung carcinoma also were examined immunohistochemically using the rabbit antihuman SLPI antibody.

RESULTS

The results of the current study confirmed that the serum levels of SLPI in patients with primary lung carcinoma were higher than those in healthy subjects, and further found there was no significant correlation between serum SLPI levels and C-reactive protein in lung carcinoma patients without pneumonia. When classifying primary lung carcinoma by its histology, SLPI levels in patients with adenocarcinoma and squamous cell carcinoma were significantly higher than in those in patients with small cell lung carcinoma (SCLC). In patients with nonsmall cell lung carcinoma (NSCLC), the SLPI levels in the advanced group (International Union Against Cancer Stages III and IV disease; n = 35) were significantly elevated compared with the nonadvanced group (Stages I and II disease; n = 12), and such elevated SLPI levels were reduced in some cases by an efficient response to surgical therapy or chemotherapy. Immunohistochemical studies showed that all the NSCLC tissues were stained with anti-human SLPI antibody, whereas staining was not noted in any of the SCLC tissues.

CONCLUSIONS

The authors believe that the findings of the current study demonstrate that cells of NSCLC produce SLPI. Furthermore, they suggest that serum SLPI levels in serum may be a helpful marker in patients with NSCLC unaccompanied by pneumonia, and that SLPI also could be used as an immunohistochemical marker to distinguish between NSCLC and SCLC.

Secretory leukocyte protease inhibitor, an inhibitor of neutrophil activation, is elevated in serum in human sepsis and experimental endotoxemia

OBJECTIVES

To document changes in serum secretory leukocyte protease inhibitor (SLPI) in human sepsis and in experimental endotoxemia in vivo. To compare changes in serum SLPI in human sepsis with changes in interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-alpha. To determine whether or not changes in SLPI correlate with the severity of multiple organ dysfunction syndrome as measured by the maximal multiple organ dysfunction score. Finally, because neutrophils have been implicated in tissue injury associated with organ dysfunction, to determine whether recombinant human SLPI blocks activation of isolated human neutrophils.

DESIGN

Case-control study and ex-vivo cellular assay.

SETTING

Surgical intensive care unit and clinical research center of university hospitals; laboratory of a medical school.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There was a significant dose-dependent elevation (50.2+/-4.0 ng/mL, p = .01) in plasma SLPI 12 hrs after administration of lipopolysaccharide to seven healthy adults (36.4+/-2.3 ng/mL). Further, serum concentrations of SLPI (132+/-15 ng/mL) were elevated in septic surgical patients compared with healthy controls (43+/-2 ng/mL, p < .01) and nonseptic surgical controls (69+/-10 ng/mL, p = .01). Serum SLPI concentrations correlated (r2 = .71, p < .01) better with organ dysfunction as measured by maximal multiple organ dysfunction score than did serum IL-6 (r2 = .49, p < .01), IL-10 (r2 = .05, p = .22), or TNF-alpha (r2 = .02, p = .44). We found that recombinant human SLPI in vitro inhibits TNF-alpha-induced hydrogen peroxide production by human neutrophils (ID50 = 1-2 microg/mL).

CONCLUSIONS

Serum SLPI is elevated in human sepsis and experimental endotoxemia. Maximal concentrations of serum SLPI correlate significantly with maximal multiple organ dysfunction scores in patients with sepsis. Secretory leukocyte protease inhibitor may function to limit ongoing neutrophil-mediated tissue injury associated with organ dysfunction.

Methods for quantitation of human neutrophil proteins, a survey

Neutrophils contain a variety of proteins that endow the cell with its capacity to migrate towards and eliminate microbial pathogens. Many of these proteins are largely or exclusively localized to neutrophils. It is therefore of interest to quantitate these proteins in a variety of clinical settings as well as in basic research. The aim of this survey is to give an introduction to some of the more commonly used methods for quantitation of neutrophil proteins and to discuss advantages and problems of the different methods and the relevance of quantitating neutrophil proteins in different biological settings.

Structure of the murine secretory leukoprotease inhibitor (Slpi) gene and chromosomal localization of the human and murine SLPI genes

Secretory leukoprotease inhibitor (SLPI) is a serine protease inhibitor involved in antineutrophil elastase protection at inflammatory sites. To elucidate both the function and regulation of SLPI in vivo, we isolated and characterized the mouse Slpi gene. An entire 3-kb mouse Slpi gene fragment was sequenced, including an 0. 8-kb 5'-flanking region, the 2.2-kb Slpi gene, and a 0.1-kb 3'-flanking region. The mouse Slpi gene spans 2,222 base pairs containing four exons and three introns. All splicing borders between exons and introns are conserved as predicted by GT-AG rules. Using primer extension analysis, the transcription start site was located 20 nucleotides upstream from the methionine (ATG) initiation codon. At the defined transcription start site, the sequence TCA+1GAGC is present. These results indicate that both mouse and human genomic structure are highly conserved. Using fluorescence in situ hybridization, we confirmed that, consistent with the genomic similarity, the human SLPI gene is localized on chromosome 20q12-13. 2 and the mouse homologue on chromosome 2H, which are syntenic with each other.

Bacterial pneumonia causes augmented expression of the secretory leukoprotease inhibitor gene in the murine lung

The cDNA of murine secretory leukoprotease inhibitor (SLPI) was cloned from a mouse lung cDNA library. The amino acid sequence deduced from the cDNA showed 58 and 51% homology with those of human and porcine SLPI, respectively. A two-domain structure with similar amino acid sequences, four intradomain disulfide bonds, and high proline content, which are characteristics common to human and porcine SLPI, was also found in the mouse protein. The amino acid residues for the signal sequence and active site are also conserved in mouse SLPI. RNase protection assay showed the expression of the SLPI gene in liver, intestine, spleen, and epididymis, suggesting the distribution of SLPI in tissues other than lung and seminal vesicles. In the lung infected with Streptococcus pneumoniae strain FP1284, 10 h after inoculation of bacteria the number of SLPI mRNA transcripts was three times higher than baseline. The increased level of expression remained constant for at least 48 h. This result clearly contrasts to that obtained for spleen, in which the SLPI mRNA transcript level was mostly unchanged during the course of pneumonia. These facts suggested the local regulation of the SLPI gene expression in vivo in response to inflammatory stimuli at the site of inflammation.

Serum secretory leukoprotease inhibitor levels in chronic bronchitis and Sjögren's syndrome

Serum secretory leukoprotease inhibitor (SLPI) is synthesized and secreted by serous cells in airway glands, and the serum level is speculated to reflect airway gland hyperplasia. To test this hypothesis, we measured the serum SLPI in 38 clinically stable patients with chronic bronchitis (3F and 35M; 58 +/- 2 years, mean +/- S.E.M.) (group CB), 24 patients with Sjögren's syndrome (24F; 52 +/- 3 years) (group SG), and compared it with 12 healthy control subjects (6F and 6M; 54 +/- 3 years) (group CN) using an enzyme-linked immunosorbent assay (ELISA). The serum SLPI from group CB (105 +/- 8 ng/ml) was significantly higher than that from group CN (60 +/- 2 ng/ml) and further, it significantly correlated with sputum volume per day. Although the mean value of serum SLPI from group SG (64 +/- 5 ng/ml) was not different from that from group CN, serum SLPI significantly correlated with the duration of respiratory symptoms (cough and/or sputum) in group SG. In conclusion, serum SPLI level reflects airway gland hyperplasia, suggesting that SLPI measurement is a possible laboratory method to estimate airway glandular hyperplasia.

Modulation of secretory leukoprotease inhibitor gene expression in human bronchial epithelial cells by phorbol ester

Secretory leukoprotease inhibitor (SLPI), a 12-kD nonglycosylated serine antiprotease, helps to protect the epithelial surface of the airways from the destructive capacity of neutrophil elastase. Based on the recognition that SLPI levels can increase in the presence of airway inflammation, we hypothesized that inflammatory stimuli should modulate the expression of the SLPI gene in airway epithelial cells. To evaluate this, the modulation of SLPI gene expression with various inflammatory stimuli was evaluated in the HS-24 human bronchial epithelial cell line. After preliminary studies showed that several inflammatory mediators enhanced SLPI messenger RNA (mRNA) levels, PMA was used as a model inflammatory stimulus. PMA significantly increased the level of 0.7-kb SLPI mRNA transcripts in HS-24 cells in a dose- and time-dependent fashion and increased the amount of SLPI protein in the culture supernatant. Nuclear run-on analyses showed that the SLPI gene transcription rate increased approximately twofold after PMA stimulation. Transfection studies using fusion genes composed of fragments of up to 1.2 kb of the 5' flanking sequence of the SLPI gene and a luciferase reporter gene demonstrated potent promoter activity in the 131-bp segment (-115 to +16 relative to the transcription start site), and all longer segments up to 1.2 kb, whereas smaller segments showed low promoter activity. An 18-bp element (-98 to -115), in a region with homology to PMA-responsive regions in the Moloney murine leukemia virus enhancer and the IL-8 gene, was shown to be of importance in the level of transcription of the SLPI gene. However, this element was not responsible for the upregulation of SLPI gene expression by PMA. Evaluation of HS-24 cells in the presence of actinomycin D demonstrated that SLPI mRNA transcripts were very stable and became more so in the presence of PMA. Thus, SLPI gene expression in airway epithelial cells can be upregulated by an inflammatory stimulus, and this modulation is regulated at both the transcriptional and posttranscriptional levels. These mechanisms of SLPI upregulation likely play a role in defending the epithelial surface in the local milieu of inflammatory lung diseases.