Mannose-binding lectin promoter and structural gene variants in sarcoidosis

BACKGROUND

Sarcoidosis is a chronic granulomatous disease of unknown aetiology. Studies have suggested that the causative agent may be an infectious micro-organism. The mannose binding lectin (MBL) is involved in innate immunity to a wide range of micro-organisms. Mutations in the promoter region and exon 1 of the MBL gene occur with high frequency and are associated with reduced serum levels of MBL and increased susceptibility to microbial diseases. This study investigated whether MBL variants predispose to sarcoidosis by increasing their susceptibility to micro-organisms.

METHODS

MBL gene promoter and exon 1 variants were detected by sequence specific primer polymerase chain reaction (SSP-PCR) in 167 UK Caucasian sarcoidosis patients and 164 control subjects. Severity of pulmonary disease outcome among patients was assessed by radiography after a minimum of 4 years from disease onset and classified as mild, moderate, and severe disease categories, accordingly.

RESULTS

MBL variant frequencies were similar in patients and controls studied. Among sarcoidosis patients, the frequencies of variants were similar regardless of severity of disease outcome. The average patient ages at time of diagnosis were similar for all MBL genotypes.

CONCLUSIONS

MBL gene variants do not appear to influence susceptibility to sarcoidosis, age of disease onset, or severity of disease.

Polymorphic analysis of the high-affinity tumor necrosis factor receptor 2

The tumor necrosis factor receptor 2 (TNF-RII, CD120b, TNF-R p75/80) gene has recently been characterised. It is located on chromosome 1p362 and consists of 10 exons and 9 introns A number of biallelic polymorphisms have been found in exons 4, 6, 9 and 10 based on differences between published sequences. In this study we have used polymerase chain reaction methodology in association with sequence-specific primers (PCR-SSP) incorporating mismatches at the 3' end to identify these polymorphisms. We were able to confirm the presence of a single biallelic polymorphism in exon 6 corresponding to a (T/G) at nucleotide 676 of TNF-RII mRNA (gb:M32315) which results in an amino acid change and three biallelic polymorphisms in exon 10 (in the3'UTR) corresponding to (A/G) at nucleotide 1663, (T/G) at nucleotide 1668 and a (C/T) at nucleotide 1690 of gb:M32315, whereas no polymorphisms were observed in exons 4 and 9. Here we report that in 192 unrelated UK Caucasian individuals the allele frequencies determined by direct counting were: 676-T (0.77), 1663-G (0.51), 1668-T (0.95), and 1690-T (0.64) and the calculated gene frequencies were; 676-T (0.52), 676-G (0.12); 1663-G (0.30), 1663-A (0.28); 1668-T (0.77), 1668-G (0.025); and 1690-T (0.40), 1690-C (0.20). Furthermore, the presence of an A allele at nucleotide position 1663 was found to be strongly associated with the presence of a C allele at nucleotide position 1690 and a G allele at nucleotide position 1668 whereas the presence of a G allele at position 1663 was associated with the absence of a C allele at nucleotide position 1690.

Different cytokine profiles in cryptogenic fibrosing alveolitis and fibrosing alveolitis associated with systemic sclerosis: a quantitative study of open lung biopsies

Differences in the inflammatory response and prognosis of cryptogenic fibrosing alveolitis (CFA) and that associated with systemic sclerosis (FASSc) are beginning to emerge. It is hypothesized that these differences may be reflected in a distinct pattern of T-helper (Th)-1 and Th-2-type cytokines. Open lung biopsies were obtained from clinically well-documented cases of CFA and FASSc and, as a control, compared with grossly and histologically normal parenchyma obtained from smokers whose lungs were resected for cancer (n=5 in each group). In situ hybridization (ISH) was applied to the samples using anti-sense and sense 35S-labelled riboprobes to detect messenger ribonucleic acid (mRNA) for interleukins (IL)-2, IL-4, IL-5 and interferon (IFN)-gamma. Between 52-91% of cells expressing the cytokines studied were present in the alveolar interstitium rather than in lumenal cells or the alveolar epithelial lining. The highest values for all four cytokines were present in the patients with FASSc, i.e., 22-39 ISH positive cells x mm(-2) alveolar tissue compared with 1-19 cells x mm(-2) and 4-5 cell x mm(-2) in CFA and control subjects, respectively. Whereas the proportions of the four cytokines in FASSc were similar to the control subjects, IL-4 and IL-5 predominated significantly in CFA (p<0.001). For example, the ratio of IL-5 to IFN-gamma was 22:1 in CFA, significantly higher than in the cases with FASSc (2:1) or the control subjects (4:1) (p<0.05). In conclusion, cryptogenic fibrosing alveolitis is an inflammatory condition which is characterized, like asthma, by a predominance of gene expression for T-helper-2-type regulatory cytokines, whereas cryptogenic fibrosing alveolitis associated with systemic sclerosis appears to have a distinct mixed T-helper-1/T-helper-2 functional phenotype and a greater number of cells expressing each of these pro-inflammatory cytokines.

Exhaled nitric oxide is increased in active fibrosing alveolitis

STUDY OBJECTIVES

Interstitial inflammation is a major aggravating factor in fibrosing lung disease associated with scleroderma (FASSc) and cryptogenic fibrosing alveolitis (CFA). Exhaled nitric oxide (NO) production is increased in asthma and bronchiectasis and reflects the degree of inflammation. We investigated whether measuring levels of exhaled NO is valuable in assessing disease activity in patients with CFA and patients with FASSc.

MEASUREMENTS AND RESULTS

NO levels were measured in 11 patients with CFA (mean age +/- SEM, 58 +/- 12 years old; 5 were male) and 17 patients with FASSc (mean age, 48 +/- 9 years old; 5 were male), and they were compared to BAL cell counts and lung function. Patients with CFA and FASSe had elevated NO levels (11.2 +/-1.0 parts per billion [ppb] and 9.8 +/- 1.0 ppb, respectively; p > 0.05), whereas in a group of 13 nonsmoking normal subjects, the NO levels were not elevated (6.9 +/- 0.5 ppb; p < 0.05). Patients with FASSc (n = 8) who had active BAL (defined as either lymphocytes > 14%, neutrophils > 4%, or eosinophils > 3%) had significantly higher NO levels (13.2 +/- 1.8 ppb), and neutrophil (16.5 +/- 4.0%) and lymphocyte (26.8 +/- 3.4%) BAL cell counts than did patients with FASSc who had inactive BAL (6.7 +/- 1.2 ppb; 1.3 +/- 1.0% and 7.5 +/- 1.3%, respectively; p < 0.05). There was a significant correlation between exhaled NO and lymphocyte cell count in patients with FASSc (r = 0.58; p < 0.05). All patients with CFA had active BAL; however, those treated with corticosteroids (12.9 +/- 1.0% ppb, p < 0.05) had lower NO levels (9.0 +/- 1 ppb) and higher BAL lymphocyte cell couits (16.6 +/- 2.0%) than did those not treated with corticosteroids (7.2 +/- 1.7%; p < 0.05).

CONCLUSIONS

We conclude that exhaled NO may be a useful addition to BAL cell counts in disease monitoring.

Detection of human retrovirus 5 in patients with arthritis and systemic lupus erythematosus

OBJECTIVE

To examine whether human retrovirus 5 (HRV-5) infection is associated with autoimmune rheumatic disease.

METHODS

DNA from patients with various disorders including inflammatory diseases and from normal subjects was tested by nested polymerase chain reaction (PCR) for HRV-5 proviral DNA. Positive results were confirmed by DNA sequencing.

RESULTS

HRV-5 proviral DNA was detected in 53% of synovial samples from arthritic joints, in 12% of blood samples from patients with rheumatoid arthritis (RA), and in 16% of blood samples from patients with systemic lupus erythematosus. In contrast, it was not detectable by PCR of affected tissues from patients with several other autoimmune diseases and was found in only 1 of >200 tissue specimens obtained at autopsy from non-RA patients. Sequence analysis of the amplified viral segment showed genetic variation between samples with maintenance of the open reading frame, typical of a replicating infectious retrovirus.

CONCLUSION

This is the first report of the frequent detection of HRV-5 in any disease. We propose that the possible involvement of HRV-5 in autoimmune and rheumatic disease should be investigated further.

Fibronectin gene polymorphisms associated with fibrosing alveolitis in systemic sclerosis

Systemic sclerosis (SSc), a multisystem immunologic disease of unknown etiology, is commonly manifested in the lung as fibrosing alveolitis (FASSc). There is evidence to support the role of genetic factors in the predisposition to pulmonary fibrosis in SSc (HLA DR3/DR52a). This association is not complete and other candidate genes are likely involved. Of these, fibronectin is a growth factor known to play a crucial role in lung fibrosis. Our study investigated whether polymorphisms of the fibronectin gene are associated with lung fibrosis in SSc. Using the polymerase chain reaction and the restriction enzymes HaeIII, MspI, HindIII, and TaqI, we assessed the restriction fragment length polymorphisms (RFLPs) in 161 patients with SSc and 253 healthy control subjects from the United Kingdom. For each restriction enzyme, three genotypes were possible corresponding to the presence of the cutting site on neither, one, or both chromosomes (HaeIII AA, AB, BB; MspI CC, CD, DD; HindIII EE, EF, FF; TaqI GG, GH, HH). There was a significant decrease of genotype BB (FASSc: 17%, control: 34%; Pcorr = 0.006) with a reciprocal increase of genotype AB (FASSc: 62%, control: 46%; Pcorr = 0.022) in FASSc with the HaeIII RFLP. A significant decrease of genotype DD was observed in FASSc (FASSc: 28%, control: 41%; Pcorr = 0.038) with the MspI RFLP. The coassociation of genotypes AB (HaeIII RFLP) and CD (MspI RFLP) was present in 45% of the FASSc group (P = 0.0059), with an increased relative risk of developing fibrosing alveolitis of 1.988. We conclude that genotypes of the fibronectin gene are useful prognostic factors in SSc, helping to predict individuals likely to develop pulmonary fibrosis.

8-Isoprostane as a biomarker of oxidative stress in interstitial lung diseases

Oxidative stress contributes to the pathophysiology of interstitial lung diseases, such as cryptogenic fibrosing alveolitis (CFA), fibrosing alveolitis associated with systemic sclerosis (FASSc) and sarcoidosis. F2-isoprostanes are a series of prostaglandin (PG) F2-like compounds produced in vivo independent of cyclooxygenase, as products of the radical-catalyzed lipid peroxidation. Measurement of the concentrations of F2-isoprostanes has proved to be valuable in assessing oxidative stress in vivo. The aim of this study was to measure 8-epi-PGF2alpha concentrations, one of the most abundant F2-isoprostane in humans, in bronchoalveolar lavage (BAL) in normal subjects and to compare them to those observed in patients with CFA (n = 9), FASSc (n = 8) and sarcoidosis (n = 10). 8-epi-PGF2alpha was detectable in BAL fluid in normal subjects (9.6 +/- 0.8 pg/ml) and its concentrations were increased approximately 5-fold in patients with CFA (47.4 +/- 7.0, p < 0.001) and FASSc (43.2 +/- 3.3, p < 0. 001). 8-epi-PGF2alpha was also increased in patients with sarcoidosis, although to a lesser extent (12.0 +/- 0.70 pg/ml, p < 0. 01). No correlation between 8-epi-PGF2alpha and either lung function tests or BAL cell types was observed in any group of patients. Our study shows that the level of oxidative stress is enhanced in patients with interstitial lung diseases as reflected by increased concentrations of 8-epi-PGF2alpha in BAL fluid.

Sequential identification of apoptotic and necrotic cells on individual cytospin preparations

Here, we describe a simple methodology which allows the consecutive differentiation of apoptotic and necrotic cells on the same cytospin preparation of fresh and cultured cells. In this methodology, necrotic cells are initially identified on the cytospin preparations using trypan blue followed by the identification of in situ DNA fragmentation using the TUNEL assay. Identification of trypan blue and TUNEL positive cells in the same section permits the simultaneous assessment of necrotic and apoptotic cells.

The source and role of RANTES in interstitial lung disease

The chemokine "regulated on activation, normal T-cell expressed and secreted" (RANTES) is a potent eosinophil and lymphocyte attractant with particular preference for CD45RO+ T-cells and eosinophils. These cells accumulate in the lungs of patients with sarcoidosis and fibrosing alveolitis. The purpose of this study was to determine whether RANTES mediates the inflammatory cell influx in these diffuse lung diseases. Cell types and number of bronchoalveolar cells expressing RANTES protein were investigated by immunocytochemistry using lavage cells obtained from 22 patients and 11 control subjects. Subsequently, RANTES messenger ribonucleic acid (mRNA) was semiquantitated using reverse transcription polymerase chain reaction (RT-PCR) methodology in unseparated lavage cell pellets in 26 patients and 13 control subjects. Cells expressing RANTES mRNA were identified by in situ hybridization. RANTES protein expression in lower respiratory tract (LRT) cells was identified in all study groups. The percentage of RANTES+ lavage cells in sarcoidosis was higher than in controls. RANTES was localized in the cytoplasm, mainly in alveolar macrophages (CD68+ cells) in sarcoidosis, and both in alveolar macrophages and eosinophils in fibrosing alveolitis. The same cell types which expressed RANTES protein expressed RANTES mRNA, as assessed by in situ hybridization. Sarcoidosis patients had higher levels of RANTES mRNA than the other groups. RANTES protein was higher in individuals with abnormal lymphocyte numbers: RANTES protein and mRNA expression was significantly correlated with lavage CD45RO+ lymphocyte numbers. These results indicate that RANTES may mediate T-lymphocyte influx in diffuse lung disease, particularly sarcoidosis. Moreover, they suggest that the cellular source of RANTES is the alveolar macrophage in sarcoidosis, and both macrophages and eosinophils in fibrosing alveolitis.

Up-regulation of IL-8 secretion by alveolar macrophages from patients with fibrosing alveolitis: a subpopulation analysis

Neutrophil accumulation in the lower respiratory tract of patients with fibrosing alveolitis is thought to be facilitated by IL-8, a neutrophil chemoattractant primarily secreted by mononuclear phagocytes. The aims of this study were: (i) to explore IL-8 secretion by lung and blood mononuclear phagocytes in subjects with cryptogenic fibrosing alveolitis, systemic sclerosis with and without fibrosing alveolitis, sarcoidosis and normal individuals; (ii) to examine IL-8 secretory heterogeneity in alveolar macrophages and peripheral blood monocytes; and (iii) to correlate alveolar macrophage phenotypic profile to IL-8 secretion. We observed that more monocytes secreted IL-8 than autologous macrophages and that there was heterogeneity in the in vitro IL-8 secretion by alveolar macrophages and peripheral blood monocytes. IL-8 secretion by alveolar macrophages was significantly higher in subjects with fibrosing alveolitis compared with subjects without fibrosing alveolitis, due to a higher percentage of IL-8-secreting alveolar macrophages in the fibrotic group both in the absence (P < 0.002) and presence of lipopolysaccharide (LPS) (P < 0.04) and correlated with bronchoalveolar lavage neutrophil percentage. Using the MoAbs RFD1, RFD7 and RFD9, that distinguish subsets of alveolar macrophages, we have been able to identify associations between secretion of IL-8 and smaller cells and the cells identified by the MoAb RFD7. In situ hybridization of the bronchoalveolar lavage cell population revealed that alveolar macrophages are the predominant source of IL-8 in the lung. We conclude that there is an increased number of IL-8-secreting alveolar macrophages in the lungs of patients with fibrosing alveolitis, and IL-8 secretion by these cells is associated with specific phenotypic profile expression.

Diverse cellular TGF-beta 1 and TGF-beta 3 gene expression in normal human and murine lung

A role for transforming growth factor-beta 1, (TGF-beta 1) has been proposed in lung development and in the pathogenesis of pulmonary disease. However, previous studies have not delineated the cells expressing TGF-beta 1 in normal adult lung, nor compared its gene expression with that of other TGF-beta isoforms. We used digoxigenin-labelled riboprobes to localize TGF-beta 1 and TGF-beta 3 gene expression in normal adult human and mouse lung. This procedure was technically simple, providing excellent resolution. TGF-beta 1 and TGF-beta 3 messenger ribonucleic acid (mRNA) transcripts were detected in a wide variety of cells. In human lung, mRNA for both isoforms was localized to bronchiolar epithelium and alveolar macrophages. TGF-beta 1, but not TGF-beta 3 mRNA was detected in mesenchymal and endothelial cells. In murine tissue, TGF-beta 1, mRNA was localized to bronchiolar epithelium, Clara cells, mesenchymal cells, pulmonary endothelium and alveolar cells, including macrophages. TGF-beta 3 mRNA was similarly distributed but not detected in endothelium. In summary, using a nonisotopic technique in lung tissue, we have detailed the cells expressing the transforming growth factor-beta 1 and beta 3 genes in human and murine lung. There was widespread expression of these cytokines in normal lung consistent with autocrine or paracrine roles in regulating cellular turnover, immune defence and matrix protein metabolism.

Neutrophil activation in fibrosing alveolitis: a comparison of lone cryptogenic fibrosing alveolitis and systemic sclerosis

Fibrosing alveolitis complicating systemic sclerosis (FASSc) carries a better prognosis than lone cryptogenic fibrosing alveolitis (CFA). We wanted to determine whether this improved prognosis is associated with differential neutrophil migration and activation in the lower respiratory tract. We therefore compared bronchoalveolar lavage (BAL) neutrophil numbers and levels of neutrophil-derived enzymes in FASSc, CFA and normal individuals. Bronchoalveolar lavage was performed on 45 subjects (FASSc n = 20; CFA n = 15; normals n = 10); cell counts and levels of neutrophil-derived enzymes, myeloperoxidase, elastase (total elastase and elastase/alpha 1 antitrypsin complexes), collagenase and lactoferrin were measured. Lung function testing was performed in subjects with fibrosing alveolitis. Significant differences in the levels of collagenase, myeloperoxidase and elastase/ alpha 1-antitrypsin complexes were present in the BAL fluid from the three groups. Patients with CFA had significantly higher neutrophil percentages and levels of collagenase and myeloperoxidase than those with FASSc. Disease extent, as judged by lung volumes and gas transfer, was comparable in the CFA and FASSc groups. Forced vital capacity (% predicted) was significantly lower in patients with evidence of increased neutrophil enzyme release than those without. We conclude that: 1) increased neutrophil migration to the lung is accompanied by release both of primary and secondary granule enzymes in cryptogenic fibrosing alveolitis; and 2) the lower amounts of neutrophil products in fibrosing alveolitis complicating systemic sclerosis may account for the improved prognosis, even when disease is as extensive as in cryptogenic fibrosing alveolitis.

Interleukin-8. Differential expression in lone fibrosing alveolitis and systemic sclerosis

Fibrosing alveolitis may occur alone (CFA) or in association with systemic sclerosis (FASSc). FASSc was recently shown to have a prognostic advantage over CFA. Because interleukin-8 (IL-8) is likely to be a major determinant of neutrophil alveolitis, we evaluated IL-8 expression in patients with CFA and FASSc and compared it with that in normal individuals and sarcoidosis and systemic sclerosis patients without pulmonary involvement (SSc no FA). IL-8 protein in bronchoalveolar lavage fluid (BALF) was assessed by immunoassay, and IL-8 mRNA expression was assessed using Northern analysis and reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization of lung parenchyma. Compared with normal subjects, IL-8 concentration was significantly greater in both CFA (p < 0.001) and FASSc groups (p < 0.05) but no different in sarcoidosis. The IL-8 concentration in CFA was higher than in FASSc (p < 0.01) and was related to BAL % neutrophils (rs = 0.48, p < 0.01). IL-8 mRNA expression evaluated by Northern analysis was seen only in patients with CFA and FASSc and was related to BAL % neutrophils (rs = 0.63, p < 0.01). We suggest that IL-8 is a key factor in the pathogenesis of fibrosing alveolitis and that the poorer prognosis of CFA compared with FASSc is related to higher levels of IL-8 within the lower respiratory tract.

Activation of peripheral blood mononuclear cells in bronchoalveolar lavage fluid from patients with sarcoidosis: visualisation of single cell activation products

BACKGROUND

Interstitial lung diseases are characterised by the recruitment of mononuclear cells to disease sites where maturation occurs and activation products, including lysozyme (LZM), are released. Analysis of in vitro cell culture supernatants for activation products masks the functional heterogeneity of cell populations. It is therefore necessary to examine the secretion of activation products by single cells to assess whether the activation of newly recruited mononuclear phagocytes at the sites of disease in the lung is uniform and controlled by the local microenvironment.

METHODS

The reverse haemolytic plaque assay was used to evaluate, at a single cell level, the ability of bronchoalveolar lavage (BAL) fluid from seven patients with sarcoidosis to activate Ficoll-Hypaque-separated peripheral blood mononuclear cells by comparison with BAL fluid from six normal volunteers and nine patients with systemic sclerosis. Monolayers of peripheral blood mononuclear cells and sheep red blood cells were cultured either alone or in the presence of 20% (v/v) BAL fluid with a polyclonal anti-LZM antibody. LZM/anti-LZM complexes bound to red blood cells surrounding the secreting cells were disclosed following complement lysis of red blood cells and quantification of plaque dimensions using microscopy and image analysis.

RESULTS

Bronchoalveolar lavage fluid from all the patients with sarcoidosis increased LZM secretion by peripheral blood mononuclear cells compared with unstimulated mononuclear cells. By contrast, BAL fluid from the other individuals had no effect on LZM secretion.

CONCLUSIONS

Single cells activated by BAL fluid can be evaluated by the reverse haemolytic plaque assay. BAL fluid from patients with sarcoidosis, but not from patients with systemic sclerosis or normal individuals, contains components capable of activating mononuclear phagocytes to secrete lysozyme.