Estrogen and Progesterone Therapy and Meningiomas

Meningiomas are common intracranial tumors with a female predominance. Their etiology is still poorly documented. The role of sexual hormones has long been evoked, and data have been conflicting across studies. However, a dose-dependent relationship between the incidence and growth of meningiomas and hormonal treatment with the progestin cyproterone acetate (CPA) has recently been established. CPA-associated meningiomas seem to be mainly located in the anterior and middle skull base, are more likely to be multiple, may harbor P1K3CA mutations in up to one-third of cases, and are more common with a longer duration of treatment. A similar but lower risk of meningiomas has been recently reported with the use of chlormadinone acetate and nomegestrol acetate as progestin treatments. Concerning hormonal replacement therapy (HRT) in menopausal patients, evidence from epidemiological studies seem to favor an increased risk of meningiomas in treated patients although a recent study failed to show an increased growth of meningiomas in HRT treated vs nontreated patients. Until larger studies are available, it seems wise to recommend avoiding HRT in patients with meningiomas. Evidence from published data does not seem to support an increased risk of meningiomas with oral contraceptive oral contraceptive (OR) use. Data are too scarce to conclude on fertility treatments. Based on studies demonstrating the expression of hormonal receptors in meningiomas, therapies targeting these receptors have been tried but have failed to show an overall favorable clinical outcome in meningioma treatment.

The ITGAV rs3738919-C allele is associated with rheumatoid arthritis in the European Caucasian population: a family-based study

The integrin αvβ3, whose αv subunit is encoded by the ITGAV gene, plays a key role in angiogenesis. Hyperangiogenesis is involved in rheumatoid arthritis (RA) and the ITGAV gene is located in 2q31, one of the suggested RA susceptibility loci. Our aim was to test the ITGAV gene for association and linkage to RA in a family-based study from the European Caucasian population.

Two single nucleotide polymorphisms were genotyped by PCR-restriction fragment length polymorphism in 100 French Caucasian RA trio families (one RA patient and both parents), 100 other French families and 265 European families available for replication. The genetic analyses for association and linkage were performed using the comparison of allelic frequencies (affected family-based controls), the transmission disequilibrium test, and the genotype relative risk.

We observed a significant RA association for the C allele of rs3738919 in the first sample (affected family-based controls, RA index cases 66.5% versus controls 56.7%; P = 0.04). The second sample showed the same trend, and the third sample again showed a significant RA association. When all sets were combined, the association was confirmed (affected family-based controls, RA index cases 64.6% versus controls 58.1%; P = 0.005). The rs3738919-C allele was also linked to RA (transmission disequilibrium test, 56.5% versus50% of transmission; P = 0.009) and the C-allele-containing genotype was more frequent in RA index cases than in controls (RA index cases 372 versus controls 339; P = 0.002, odds ratio = 1.94, 95% confidence interval = 1.3–2.9).

The rs3738919-C allele of the ITGAV gene is associated with RA in the European Caucasian population, suggesting ITGAV as a new minor RA susceptibility gene.

HSPD1 is not a major susceptibility gene for rheumatoid arthritis in the French Caucasian population

The heat shock 60-kDa protein 1 (HSP60) is involved in immune and inflammatory reactions, which are hallmarks of rheumatoid arthritis (RA). HSP60 is encoded by the HSPD1 gene located on 2q33, one of the suggested RA susceptibility loci in the French Caucasian population. Our aim was to test whether HSPD1 is a major susceptibility gene by studing families from the French Caucasian population. Three single nucleotide polymorphisms (SNPs) were studied in 100 RA trio families, and 100 other families were used for replication. Genetic analyses were performed by comparing allelic frequencies, by applying the transmission disequilibrium test, and by assessing the genotype relative risk. We observed a significant RA association for the C/C genotype of rs2340690 in the first sample. However, this association was not confirmed when the second sample was added. The two other SNPs and the haplotype analysis did not give any significant results. We conclude that HSPD1 is not a major RA susceptibility gene in the French Caucasian population.

Paget's disease of bone in the French population: novel SQSTM1 mutations, functional analysis, and genotype-phenotype correlations

Mutation screening of the SQSTM1 gene in 94 French patients with PDB revealed two novel point-mutations (A381V and L413F) and two new compound heterozygous genotypes (P392L/A381V and P392L/A390X). Functional analysis showed an increased level of SQSTM1/p62 protein in PDB patients and truncated forms of the protein encoded by the A390X allele. Clinical data indicate that PDB patients with SQSTM1 mutation are younger at PDB diagnosis and have more extensive bone lesions.

INTRODUCTION

Paget's disease of bone (PDB) is a common chronic disease of the skeleton, with a strong genetic component. A recurrent mutation (P392L) was first identified on chromosome 5, in the Sequestosome 1 (SQSTM1) gene. Several other mutations of the SQSTM1 gene have been described in PDB patients, affecting the ubiquitin-associated domain (UBA) of the SQSTM1/p62 protein. The objectives of this study were to evaluate the frequency of the SQSTM1 mutations in French PBD patients, to study the expression of the SQSTM1/p62 protein, and to search for genotype-phenotype correlations.

MATERIALS AND METHODS

Blood was obtained from 94 unrelated French PDB patients and 100 controls for mutation screening of exons 7 and 8, encoding for the UBA domain of SQSTM1. Epstein-Barr virus (EBV)-immortalized B-cell lymphocytes were established from 13 patients, giving access to functional analysis of the gene and the SQSTM1/p62 expressions using real-time PCR and Western blot.

RESULTS

Mutations of the SQSTM1 gene were identified in 12 of the 94 PDB patients (13%). Eight patients carried P392L. Two novel missense mutations were identified: L413F and A381V. This A381V mutation and A390X were found in distinct patients already carriers of P392L. The SQSTM1/p62 protein expression in PDB patients increased when zero, one, or two mutations were present, and SQSTM1 truncated forms were associated with the A390X mutation. The mean age of PDB diagnosis was younger in patients with the SQSTM1 mutation. PDB was more extensive in patients who carried a SQSTM1 mutation.

CONCLUSIONS

Mutations of SQSTM1 are present in the French population. PDB patients with and without the SQSTM1 mutation have an increased level of SQSTM1/p62, caused by overproduction of the protein, probably involved in the pathophysiology of PDB. The presence of the SQSTM1 mutation may be a worsening factor for PDB.

Linkage proof for PTPN22, a rheumatoid arthritis susceptibility gene and a human autoimmunity gene

The tyrosine phosphatase PTPN22 allele 1858T has been associated with rheumatoid arthritis (RA) and other autoimmune diseases. RA is the most frequent of those multifactorial diseases. The RA association was usually restricted to serum rheumatoid factor positive disease (RF+). No interaction was shown with HLA-DRB1, the first RA gene. Many case-control studies replicated the RA association, showing an allele frequency increase of approximately 5% on average and large variations of population allele frequencies (2.1-15.5%). In multifactorial diseases, the final proof for a new susceptibility allele is provided by departure from Mendel's law (50% transmission from heterozygous parents). For PTPN22-1858T allele, convincing linkage proof was available only for type 1 diabetes. We aimed at providing this proof for RA. We analyzed 1,395 West European Caucasian individuals from 465 "trio" families. We replicated evidence for linkage, demonstrating departure from Mendel's law in this subset of early RA onset patients. We estimated the overtransmission of the 1858T allele in RF+ families: T = 63%, P < 0.0007. The 1858T allele frequency increased from 11.0% in controls to 17.4% in RF+ RA for the French Caucasian population and the susceptibility genotype (1858T/T or T/C) from 20.2% to 31.6% [odds ratio (OR) = 1.8 (1.2-2.8)]. In conclusion, we provided the linkage proof for the PTPN22-1858T allele and RF+ RA. With diabetes and RA, PTPN22 is therefore a "linkage-proven" autoimmunity gene. PTPN22 accounting for approximately 1% of the RA familial aggregation, many new genes could be expected that are as many leads to definitive therapy for autoimmune diseases.

Validation of the reshaped shared epitope HLA-DRB1 classification in rheumatoid arthritis

Recently, we proposed a classification of HLA-DRB1 alleles that reshapes the shared epitope hypothesis in rheumatoid arthritis (RA); according to this model, RA is associated with the RAA shared epitope sequence (72–74 positions) and the association is modulated by the amino acids at positions 70 and 71, resulting in six genotypes with different RA risks. This was the first model to take into account the association between the HLA-DRB1 gene and RA, and linkage data for that gene. In the present study we tested this classification for validity in an independent sample. A new sample of the same size and population (100 RA French Caucasian families) was genotyped for the HLA-DRB1 gene. The alleles were grouped as proposed in the new classification: S₁ alleles for the sequences A-RAA or E-RAA; S₂ for Q or D-K-RAA; S_3D for D-R-RAA; S_3P for Q or R-R-RAA; and X alleles for no RAA sequence. Transmission of the alleles was investigated. Genotype odds ratio (OR) calculations were performed through conditional logistic regression, and we tested the homogeneity of these ORs with those of the 100 first trio families (one case and both parents) previously reported. As previously observed, the S₂ and S_3P alleles were significantly over-transmitted and the S₁, S_3D and X alleles were under-transmitted. The latter were grouped as L alleles, resulting in the same three-allele classification. The risk hierarchy of the six derived genotypes was the same: (by decreasing OR and with L/L being the reference genotype) S₂/S_3P, S₂/S₂, S_3P/S_3P, S₂/L and S_3P/L. The homogeneity test between the ORs of the initial and the replication samples revealed no significant differences. The new classification was therefore considered validated, and both samples were pooled to provide improved estimates of RA risk genotypes from the highest (S₂/S_3P [OR 22.2, 95% confidence interval 9.9–49.7]) to the lowest (S_3P/L [OR 4.4, 95% confidence interval 2.3–8.4]).

New classification of HLA-DRB1 alleles supports the shared epitope hypothesis of rheumatoid arthritis susceptibility

OBJECTIVE

The shared epitope hypothesis was formulated to explain the involvement of HLA-DRB1 in rheumatoid arthritis (RA). However, several studies, which considered only the HLA-DRB1 alleles shown to be associated with RA risk, rejected this hypothesis. In this report, we propose that a different classification of HLA-DRB1 alleles be considered, based on the amino acid sequence at position 70-74.

METHODS

The fit of both HLA-DRB1 classifications was tested in 2 groups of RA patients. All subjects were recruited through the European Consortium on Rheumatoid Arthritis Families, and included 100 patients with isolated RA and 132 patients with at least 1 affected sibling.

RESULTS

The new classification produced risk estimates that fit all of the observed data, i.e., the distribution of the HLA-DRB1 genotype in the 2 patient groups, and the distribution of parental alleles shared by affected sibpairs. The risk of developing RA under this new classification depends on whether the RAA sequence occupies position 72-74 but is modulated by the amino acid at position 71 (K confers the highest risk, R an intermediate risk, A and E a lower risk) and by the amino acid at position 70 (Q or R confers a higher risk than D).

CONCLUSION

A new classification based on amino acid sequence allows us to show that the shared epitope RAA sequence at position 72-74 explains the data, with the risk of developing RA modulated by the amino acids at positions 70 and 71.

Dense genome-wide linkage analysis of rheumatoid arthritis, including covariates

OBJECTIVE

Rheumatoid arthritis (RA) is a heterogeneous disease that exhibits a complex genetic component. Previous RA genome scans confirmed the involvement of the HLA region and generated data on suggestive signals at non-HLA regions, albeit with few overlaps in findings between studies. The present study was undertaken to detect potential RA gene regions and to estimate the number of true RA gene regions, taking into account the heterogeneity of RA, through performance of a dense genome scan.

METHODS

In a study of 88 French Caucasian families (105 RA sibpairs), 1,088 microsatellite markers were genotyped (3.3-cM genome scan), and a multipoint model-free linkage analysis was performed. The statistical assessment of the results relied on 10,000 computer simulations. A covariate-based multipoint model-free linkage analysis was performed on the locations of regions with suggestive evidence for linkage.

RESULTS

Involvement of the HLA region was strongly confirmed (P = 6 x 10(-5)), and 19 non-HLA regions showed suggestive evidence for linkage (P < 0.05); 9 of these overlapped with regions suggested in other published RA genome scans. A routine 12-cM genome scan with the same families would have detected only 7 of the 19 regions, including only 4 of the 9 overlapping regions. From the 10,000 computer simulations, we estimated that 8 +/- 4 regions (mean +/- SD) were true-positives. RA covariate-based analysis provided additional linkage evidence for 3 regions, with age at disease onset, erosions, and HLA-DRB1 shared epitope as covariates.

CONCLUSION

The results of this study provide evidence of 19 non-HLA RA gene regions, with an estimate of 8 +/- 4 as true-positives, and provide additional evidence for 3 regions from covariate-based analysis.

Extractable polysaccharides of Panax quinquefolius L. (North American ginseng) root stimulate TNFalpha production by alveolar macrophages

We have investigated the immunostimulatory activity of the medicinal plant Panax quinquefolius L. (North American ginseng). Rat alveolar macrophages were treated with different extracts from 4-year old roots, and tumour necrosis factor alpha (TNF) production was used as a measure of immunostimulatory activity. Aqueous extracts of P. quinquefolius root (1-100 microg/ml) were found to significantly stimulate alveolar macrophage TNF release. Both a P. quinquefolius methanol extract containing ginsenosides (but no polysaccharides), and pure ginsenoside-Rb1, the major ginsenoside present in P. quinquefolius, were found to be inactive as TNF-stimulating agents. Significant TNF-stimulating activity was found in the extractable polysaccharide fraction, which was hydrolyzed and found to contain glucose, galactose, arabinose, rhamnose, and mannose. This represents the first evidence that North American ginseng exerts cytokine-stimulating activity on macrophages.

Studying, Working, and Living in Another EU Country

This study assessed the willingness of French youth to go and study or work for some time in another EU country. We examined three types of questions: (a) What is the overall level of willingness to go in another EU country? Does age, gender or socioeconomic status (SES) of the family influence this overall level? Which country do French youth prefer to go to? (b) Is a four-factor Push-Anti-Push-Pull-Anti-Pull model able to account for data regarding attitudes toward other countries and attitudes toward France? (c) Is this model able to predict willingness to go and study or work in another EU country, both generally and for individual countries? The overall level of willingness to go to other EU countries was not very high. Except for the United Kingdom the mean response was always located closer to the “No” pole than to the “Quite possible” pole. Gender, age, and educational level of the father did not play a role. Participants clearly preferred the United Kingdom and Spain to Germany or The Netherlands. Exploratory factor analysis showed a clearly interpretable Push-Anti-Push-Pull-Anti-Pull solution, and confirmatory factor analysis showed that this structure fits the attitudes data very well according to the usual indices. This general model, however, did not explain much of the “intent-to-go” variance. In addition, specific Pull attractiveness considerations (liking and knowing the country) played, beyond the general Push-Pull model, a notable role in the determination of willingness to go and study or work in each of the 14 EU countries.

Stimulation of interleukin-1 and -6 production in alveolar macrophages by the neotropical liana, Uncaria tomentosa (uña de gato)

Two extracts of different collections of the traditional medicine uña de gato (Uncaria tomentosa) from Peru were characterized by High Pressure Liquid Chromatography as containing approximately 6 mg/g total oxindole content prior to studies with alveolar macrophages. The plant preparations greatly stimulated IL-1 and IL-6 production by rat macrophages in a dose dependent manner in the range of 0.025-0.1 mg/ml. They were also able to enhance IL-1 and -6 in lipopolysaccharide-stimulated macrophages. The results suggest a strong immunostimulant action of this plant.

Differential effects of macrophage- and granulocyte-macrophage colony-stimulating factors on cytokine gene expression during rat alveolar macrophage differentiation into multinucleated giant cells (MGC): role for IL-6 in type 2 MGC formation

Macrophage colony-stimulating factor (M-CSF) and granulocyte-macrophage (GM)-CSF stimulate the differentiation of rat alveolar macrophages (AM) into multinucleated giant cells (MGC) with distinct phenotypes (type 1 and type 2 MGC). In the present study, we analyzed the profile of cytokine gene expression induced respectively, by M-CSF and GM-CSF during rat AM differentiation using reverse transcription-PCR. Enhanced mRNA expression for IL-1alpha, TNF-alpha, and TGF-beta1 was observed 3 h after treatment with M-CSF (50 U/ml) or GM-CSF (50 U/ml). In contrast, IL-6 mRNA expression was increased by GM-CSF but not M-CSF. Kinetic analysis indicated that GM-CSF stimulated IL-6 expression early (1.5 h), with maximal effect observed at 24 h and up to 5 days thereafter. Increased mRNA levels for IL-6 were associated with higher IL-6 activity in the culture media of differentiating AM. IL-6 activity was stimulated 3 h after treatment with GM-CSF and increased with time (up to 5 days). Interestingly, addition of exogenous IL-6 (20-100 ng/ml) alone or in combination with GM-CSF to AM cultures increased slightly and selectively the formation of MGC with type 2 phenotype. Conversely, neutralization of endogenous IL-6 during AM differentiation into MGC inhibited significantly (up to 50%) the formation of type 2 MGC. These results suggest a role for IL-6 in the formation of type 2 MGC and provide some insights into the mechanisms of MGC formation and the processes that regulate it positively.

Differential effects of macrophage- and granulocyte-macrophage colony-stimulating factors on cytokine gene expression during rat alveolar macrophage differentiation into multinucleated giant cells (MGC): role for IL-6 in type 2 MGC formation

Macrophage colony-stimulating factor (M-CSF) and granulocyte-macrophage (GM)-CSF stimulate the differentiation of rat alveolar macrophages (AM) into multinucleated giant cells (MGC) with distinct phenotypes (type 1 and type 2 MGC). In the present study, we analyzed the profile of cytokine gene expression induced respectively, by M-CSF and GM-CSF during rat AM differentiation using reverse transcription-PCR. Enhanced mRNA expression for IL-1alpha, TNF-alpha, and TGF-beta1 was observed 3 h after treatment with M-CSF (50 U/ml) or GM-CSF (50 U/ml). In contrast, IL-6 mRNA expression was increased by GM-CSF but not M-CSF. Kinetic analysis indicated that GM-CSF stimulated IL-6 expression early (1.5 h), with maximal effect observed at 24 h and up to 5 days thereafter. Increased mRNA levels for IL-6 were associated with higher IL-6 activity in the culture media of differentiating AM. IL-6 activity was stimulated 3 h after treatment with GM-CSF and increased with time (up to 5 days). Interestingly, addition of exogenous IL-6 (20-100 ng/ml) alone or in combination with GM-CSF to AM cultures increased slightly and selectively the formation of MGC with type 2 phenotype. Conversely, neutralization of endogenous IL-6 during AM differentiation into MGC inhibited significantly (up to 50%) the formation of type 2 MGC. These results suggest a role for IL-6 in the formation of type 2 MGC and provide some insights into the mechanisms of MGC formation and the processes that regulate it positively.

M-CSF and GM-CSF promote alveolar macrophage differentiation into multinucleated giant cells with distinct phenotypes

Multinucleated giant cells (MGC) are a hallmark of granulomatous reactions but the mechanisms that regulate their formation are unknown. To address this issue, we cultured resident alveolar macrophages (AM) from rat lung and examined the effects of defined cytokines on AM differentiation and MGC formation. The presence of MGC was found after 3 days in culture with maximal numbers obtained at 7 days and thereafter (up to 21 days). Macrophage colony-stimulating factor (M-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) (25-75 U/mL) stimulated the formation of MGC (up to 4-fold), whereas interleukin (IL) -3, IL-10, and interferon-gamma (IFN-gamma) had no stimulatory effect. Interestingly, MGC with distinct phenotypes were observed in AM cultures: (1) spherical MGC with 3-16 nuclei, dense cytoplasm, and lower expression of beta3 integrin (Type 1) and (2) irregular MGC with 3-30 nuclei, thin and vacuolated cytoplasm, and higher expression of beta3 integrin (Type 2). Furthermore, the actions of M-CSF and GM-CSF on AM were found to be different. GM-CSF promoted, in AM cultures, the appearance of an elongated fibroblastoid phenotype and stimulated mostly the formation of Type 2 MGC. In contrast, M-CSF did not cause significant change in the general morphology of regular AM but stimulated the appearance of both Type 1 and Type 2 MGC. Reverse transcriptase-polymerase chain reaction analysis demonstrated that, under these conditions, M-CSF induced GM-CSF gene expression in AM. In addition, neutralizing antibodies against M-CSF selectively decreased the formation of Type 1 MGC, whereas neutralizing anti-GM-CSF inhibited Type 2 formation. These data suggest that M-CSF promotes AM differentiation into Type 1 MGC, whereas GM-CSF stimulates the formation of Type 2 and that M-CSF and GM-CSF may selectively regulate in an autocrine fashion AM differentiation into distinct MGC.

Distinctive profile of alveolar macrophage-derived cytokine release induced by fibrogenic and nonfibrogenic mineral dusts

Groups of 7 Wistar rats each received a single intratracheal instillation of either saline (control), UICC chrysotile B asbestos (5 mg), or very short 4T30 chrysotile asbestos fibers (5 mg). Five animals in each group were killed at 1, 3, and 6 wk posttreatment and analyzed by bronchoalveolar lavage (BAL) for BAL cell populations and cytokine production in conjunction with histopathological assessment of lung tissue. Chrysotile B and short 4T30 chrysotile fibers induced chronic inflammatory reactions characterized by alveolar macrophage (AM) accumulation that resulted, respectively, in lung fibrosis and resolving granuloma. Alveolar macrophages (AM) obtained from rats treated with UICC chrysotile B and short 4T30 chrysotile produced enhanced levels of interleukin-1 (IL-1) and interleukin-6 (IL-6), both spontaneously and in response to lipopolysaccharide (LPS). A different pattern of response was observed for tumor necrosis factor-alpha (TNF-alpha). Fibrogenic chrysotile B caused biphasic changes characterized by significant inhibition of LPS-induced TNF-alpha release by AM 1 and 3 wk after treatment, followed by stimulation of spontaneous and LPS-induced TNF-alpha at 6 wk. In contrast, no significant change in spontaneous and LPS-induced TNF-alpha release was seen with AM from animals with resolving granuloma (4T30 group). Thus, modulation of AM-derived TNF-alpha was correlated under these conditions with the fibrogenic potential of asbestos dusts. These data support a role for TNF-alpha in fibrosis and suggest that TNF-alpha may represent a useful marker of lung damage induced by fibrogenic dusts.

Effects of amiodarone-induced phospholipidosis on pulmonary host defense functions in rats

The effect of the induction of pulmonary phospholipidosis by amiodarone on selected pulmonary host defense functions was studied in male Fischer-344 rats. One week of daily amiodarone treatment resulted in a 4.5-fold increase in total phospholipid in alveolar macrophages recovered from the lungs by bronchoalveolar lavage. The presence of the phospholipidosis had no effect on the phagocytosis of heat-killed yeast cells, the induction of luminol-dependent chemiluminescence, or the spontaneous release of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), or spontaneous and LPS-stimulated release of IL-1 by alveolar macrophages in vitro. In contrast, the LPS-stimulated release of IL-6 and TNF-alpha by phospholipidotic alveolar macrophages was enhanced compared with control cells. The pulmonary clearance of Listeria monocytogenes following intratracheal administration of the bacteria was not affected by the phospholipidotic condition. It appears that, in the context of the functions studied, the induction of pulmonary phospholipidosis by amiodarone does not impair pulmonary host defense processes in rats, and may actually be associated with the augmentation of some activities.

Histogranin, a modified histone H4 fragment endowed with N-methyl-D-aspartate antagonist and immunostimulatory activities

Histogranin is a naturally-occurring pentadecapeptide with a structure 80% homologous with that a fragment-(86-100) of histone H4. First isolated from bovine adrenal medulla, the peptide was also shown to be present in the pituitary, brain, adrenal glands, blood plasma, lungs and spleen. At the subcellular level, histogranin is concentrated in secretory vesicles and it is released from perfused bovine adrenal glands 15-35 min after stimulation with carbamylcholine as opposed to catecholamines and [Leu5]enkephalin which are released immediately after stimulation. Rat brain membranes possess specific binding sites for [125I][Ser1]histogranin with characteristics of a receptor, namely high affinity, saturability, reversibility and sensitivity to heat and proteolytic enzyme treatments. Intracerebroventricular injections of synthetic histogranin (10-100 nmol) in mice protect them against N-methyl-D-aspartate (NMDA)-induced convulsions without affecting convulsions induced by (R,S)-alpha-amino-3-hydroxy -5-methyl-4-isoxazole-propionate (AMPA), kainate and bicuculline. The peptide also binds to specific sites on human peripheral blood mononuclear cells and it evokes the release of tumor necrosis factor-alpha (TNF), interleukin-1 (IL-1) and interleukin-6 (IL-6) from isolated rat macrophages in culture. Since the structure of histone H4 is considered as one of the most conservative, it is presumed that histogranin possesses its own precursor and that its gene is distinctly expressed.

Alveolar macrophage inhibition of lung-associated NK activity: involvement of prostaglandins and transforming growth factor-beta 1

Natural killer (NK) activity plays an important role in host defense. It is likely that this defensive role is shaped by compartmental and local environmental factors. The present study investigated the regulatory effects of alveolar macrophages (AM) on lung-associated NK activity. AM and lung lymphocytes (LL) were permitted to interact in a two-chamber system which prohibited cell contact but supported diffusion of soluble factors. AM were found to inhibit NK activity from LL in a time-dependent and reversible manner. The inhibitory event was shown to be mediated by soluble factors acting upon a post-binding event(s) in the lytic pathway of LL. AM inhibition was sensitive to indomethacin treatment (10(-5) M), which caused a decrease in prostaglandin E2 (PGE2) concentrations. Quantitation of PGE2 levels and treatment of LL with exogenous PGE2 indicated that the inhibitory effect could not be exclusively due to PGE2. It was subsequently found that exogenous transforming growth factor-beta 1 (TGF-beta 1) also inhibited LL NK activity and that treatment of inhibitory AM supernatant with a neutralizing antibody to TGF-beta 1 adsorbs up to 55% of its inhibitory activity. Moreover, the amount of TGF-beta 1 found in AM-LL co-culture media (25 pg/mL) correlated well with the level of NK inhibition observed. By contrast, platelet-derived growth factor and nitric oxide did not play a significant role in mediating AM suppression. Taken together, the data suggest that AM inhibit lung NK activity by interfering with post-binding lytic event(s) through the production of PGE2 and TGF-beta 1.

Up-regulation of cytokine production in alveolar macrophages by histogranin, a novel endogenous pentadecapeptide

Recently, histogranin (HN), a newly found pentadecapeptide, was shown to enhance tumor necrosis factor (TNF) production by alveolar macrophages (AM). In this study, we have investigated whether HN was present in tissues rich with immune cells and further explored the effect of HN and [Ser1]HN on the production of TNF and other key cytokines. Relatively high levels of immunoreactive (ir)-HN were found in rat lung (14.9 pmol/g) and spleen (12.3 pmol/g), indicating its localization in close proximity to macrophages/monocytes and lymphocytes. Furthermore, HN and [Ser1]HN (10(-8)-10(-7) M) stimulated basal and lipopolysaccharide (LPS)-induced interleukin 1 (IL-1) mRNA expression and IL-1 release from rat AM. [Ser1]HN also stimulated basal and LPS-induced interleukin-6 (IL-6) release. Although HN did not affect the kinetics of cytokine production, the maximal enhancing effect of HN was seen at 3 h for TNF, 6 h for IL-1 and 18 h for IL-6. These data indicate that HN can up-regulate a cytokine cascade involving TNF, IL-1 and IL-6 and suggest a role for this endogenous peptide in immune regulation.

Characterization of histogranin receptors in human peripheral blood lymphocytes

Histogranin (HN), a peptide recently isolated from bovine adrenal medulla, is also present in the spleen. In present studies, specific high affinity binding sites for HN were characterized on membrane preparations of human lymphocytes by radioligand binding. [125I]-[Ser1]HN binding was found to be dependent on time and protein concentration and to be sensitive to trypsin treatment. The binding displayed high affinity (Kd = 1.1 +/- 0.3 nM) and saturability (Bmax = 40.2 +/- 5.0 fmol/mg protein), and it was reversed upon addition of unlabelled [Ser1]HN and closely related peptides. The relative potency of various fragments in displacing [125I][Ser1]HN binding indicated that the active core of the molecule resides inside the C-terminal fragment, HN-(6-15). Interestingly, depressed patients displayed a marked decrease in the binding activity (from 15.4 to 8.55 fmol/mg protein at 0.5 nM of [125I][Ser1]HN). The presence of high affinity HN binding sites on lymphocytes provides evidence for a modulatory role for HN in the regulation of lymphocyte functions.

Simplified high throughput protocol for northern hybridization

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Bidirectional modulation of TNF-alpha production by alveolar macrophages in asbestos-induced pulmonary fibrosis

Bronchoalveolar lavage (BAL) cells were isolated from rats 1, 3, and 6 weeks after a single intratracheal instillation of saline, UICC chrysotile asbestos (5 mg), or silica (5 mg). In asbestos-exposed rats, the pulmonary response was characterized by a significant increase in the number of alveolar macrophages (AMs) and the appearance of fibrotic lesions within 1 week. By contrast, mixed macrophage and neutrophil accumulations were observed in the silica group without evidence of fibrosis. Tumor necrosis factor-alpha (TNF-alpha) production by lipopolysaccharide (LPS)-stimulated BAL cells from asbestos-treated rats was significantly lower than controls 1 and 3 weeks after exposure. However, by 6 weeks higher levels of TNF-alpha production were noticeable in this group. Decreases in LPS-induced TNF-alpha production were also observed with BAL cells from silica-treated animals at all time points studied. Lower levels of TNF-alpha were not related to decreased BAL cell viability or the presence of a significant proportion of neutrophils in the silica group. Furthermore, biphasic changes in TNF-alpha production seen in the asbestos group were correlated with concomitant decreases (3 weeks) and increases (6 weeks) in levels of TNF-alpha mRNA in AMs. These data indicate that lower levels of TNF-alpha resulted from inhibition at the gene expression level and provide evidence for bidirectional modulation of TNF-alpha production by AMs during inflammatory reactions.

Effects of hyperthermia on natural killer cells: inhibition of lytic function and microtubule organization

Cells with natural killer activity (NK) may play an important role in host defence against tumour cells. The lytic function of NK cells is very sensitive to hyperthermic inactivation. However, cells with NK activity isolated from rat spleen and exposed to 41-42.5 degrees C for 30 min could partially recover their cytotoxic activity after incubation at 37 degrees C. The recovered cytotoxicity was still NK-specific, as it only resulted in the lysis of YAC-1 sensitive targets, and could not lyse NK-resistant P815 mastocytoma cells. Conjugate formation assay using NK cells labelled with specific monoclonal antibody (mAb) 3.2.3 indicated that the binding of NK cells to targets was not significantly affected by heat treatment. Compared to controls, however, microtubule organizing centre (MTOC) reorientation towards the region of intercellular contact was reduced by 40% in heated effector cells. This was accompanied by a greater inhibition (62-77%) of NK lytic activity. Kinetic analysis indicated that MTOC reorientation capacity recovered following incubation at 37 degrees C. MTOC recovery was maximal 4 h after treatment whereas that of lytic activity peaked at 6 h. These data indicate that NK cells recover NK-specific lytic activity after heat inactivation. Moreover, our study demonstrates that hyperthermia interferes with post-binding MTOC reorientation, and further supports a role for microtubule in secretory processes involved in NK-mediated cytolysis.

Bombesin-related peptides modulate interleukin-1 production by alveolar macrophages

We have tested the effect of bombesin (BN) and BN-related peptides on the production of interleukin-1 (IL-1) by rat alveolar macrophages. BN incubated with AM alone had no direct effect on IL-1 release. However, at concentrations ranging from 10(-11) M to 10(-6) M, BN significantly enhanced IL-1 release by AM activated with lipopolysaccharide (LPS). A typically U-shaped dose-response relationship was observed with maximal effect obtained between 10(-9) M and 10(-8) M. BN also potentiated the stimulatory effects of other IL-1 inducers including muramyl dipeptide (MDP) and granulocyte-macrophage colony stimulating factor (GM-CSF). The 2- to 3-fold enhancement in IL-1 production seen with BN was blocked by the bombesin receptor antagonist [Leu13,-psi(CH2NH)Leu14]-Bombesin. Furthermore, bombesin-related peptides, gastrin-releasing peptides, (GRP)-27 and GRP-10 also potentiated the stimulatory effects of LPS whereas Neuromedin B (NeB) had no effect. These results suggest that BN-related peptides might play an important role as local modulator(s) of cytokine production and inflammatory reactions in the lung.

Bombesin-like peptides in alveolar macrophage: increased release in pulmonary inflammation and fibrosis

Rat bronchoalveolar cells (99% alveolar macrophages (AM] were obtained by bronchoalveolar lavage and examined for their content of bombesin-like immunoreactivity (BLI) by radioimmunoassay (RIA), immunocytochemistry and high performance liquid chromatography (HPLC) analysis. Rat AM contained and released in their culture media significant levels of BLI, the major molecular form corresponding to gastrin-releasing peptide (GRP). Release of BLI by AM was not affected by in vitro activation of AM with lipopolysaccharide and muramyl dipeptide, but was enhanced following in vivo treatment with inflammatory agents. AM from animals with inflammation and fibrosis released higher levels of BLI than controls at 3 and 6 weeks after treatment. These changes were correlated with a significant increase in the proportion of low density mature AM as determined by Percoll density gradient fractionation. Together, our data indicate that increased release of BLI by AM may be related to AM maturation and support a role for bombesin-like peptides as modulator(s) of inflammatory reactions.

Influence of affinity of antibodies upon their detection by liquid phase radiobinding assay and solid phase enzyme linked immunosorbent assay. Demonstration using monoclonal antibodies raised against rDNA human proinsulin

Hybridomas producing proinsulin antibodies were cloned by limiting dilution of cell cultures obtained by fusion of splenocytes of immunized mice with immortal myeloma cells. Some proinsulin monoclonal antibodies crossreacted with labelled insulin but none did with labelled C-peptide indicating that the involved epitopes were at one of the insulin/C-peptide junctions or included in the insulin moiety. Hybridoma supernatants were assayed for IgG concentration by a solid phase assay and for ligand binding by a radiobinding assay and an enzyme linked immunosorbent assay. The half-life of immune complexes formed with radioligand was measured and, as expected, correlated with affinity as measured by the method of Scatchard. Antibody titres determined by enzyme linked immunosorbent assay did not correlate to those measured by radiobinding assay. IgG concentration correlated to enzyme linked immunosorbent assay titres but not to radiobinding assay titres. Finally, a significant correlation was found between radiobinding assay titre and the product of enzyme linked immunosorbent assay titre by the period of immune complexes. It is concluded that, except for very low affinity antibodies, enzyme linked immunosorbent assay is a capacity assay whereas radiobinding assay is influenced by both antibody concentration and affinity. The former assay is thus best suited to detecting low affinity antibodies whereas the latter is more efficient in the presence of low levels of high affinity antibodies.

Selective differences in macrophage populations and monokine production in resolving pulmonary granuloma and fibrosis

Alveolar macrophages (AM) and their production of interleukin-1-like activity (IL-1) and macrophage-derived growth factor for fibroblasts (MDGF) were examined during chronic inflammatory reactions leading to either granuloma formation or fibrosis. Groups of five rats each received, respectively, a single transtracheal injection of xonotlite, attapulgite, short chrysotile 4T30, UICC chrysotile B asbestos, or saline. One month later, such treatments induced either no change (xonotlite), granuloma formation (attapulgite and short chrysotile 4T30), or fibrosis (UICC chrysotile B). By 8 months, however, the granulomatous reactions had resolved or greatly diminished, whereas the fibrosis persisted irreversibly. Parallel examination of cell populations obtained by bronchoalveolar lavage revealed that multinucleated giant macrophages (MGC) were present in lavage fluids of animals with resolving granulomatous reactions but absent in those obtained from animals with lung fibrosis. Evaluation of monokine production by inflammatory macrophages also revealed significant differences. Enhanced production of IL-1-like activity was seen in both types of lung injury, although especially during the early stage (1 month) and decreased thereafter (8 months). By contrast, augmentation of MDGF production was observed in animals with lung fibrosis only and persisted up to 9 months. Taken together, these data indicate that production of selected cytokines, as well as AM differentiation along a given pathway, may modulate the outcome of a chronic inflammatory response.

Effects of biological response modifiers on lung natural killer activity

Natural killer (NK) activity plays an important role in host defense against tumors, especially once augmented by immunomodulators. It is likely that the modulation of NK cells is a reflection of the environment in which they reside. The current study was undertaken to characterize the response profile of lung interstitial lymphocyte natural killer (LLNK) activity to various biological response modifiers (BRM) in vitro after short term incubation (18h). The presented data show that treatment of lung lymphocytes with human recombinant interleukin 2 (rIL-2), purified rat interferon alpha/beta (IFN-alpha/beta), or murine recombinant tumor necrosis factor alpha (rTNF-alpha) resulted in a dose-dependent increase in LLNK activity. The maximum stimulation was similar for rIL-2 and IFN-alpha/beta, although a much higher concentration of IFN-alpha/beta was required to reach this level of stimulation. The maximum response to rTNF-alpha treatment was about half that seen with rIL-2 or IFN-alpha/beta and it, too, required a high concentration. By contrast, rat recombinant interferon gamma (rIFN-gamma) or murine recombinant interleukin 1 (rIL-1) failed to alter LLNK activity significantly when used alone. Furthermore, doses of IFN-alpha/beta and rTNF-alpha that had little enhancing effect were able to synergize with a suboptimal dose of rIL-2, whereas rIL-1 and rIFN-gamma failed to do so. These data demonstrate the response of lung NK activity to BRM treatment, which is important for the responsible and effective use of BRM. However the spectrum of lung NK cell response to BRM is smaller than that previously reported for NK cells from other anatomic compartments.

The effects of in vitro hyperthermia on natural killer activity from lung, blood and spleen

The in vitro effects of hyperthermia on natural killer (NK) activity from rat lung, peripheral blood and spleen were assessed. NK activity of all three compartments was very sensitive to heat shock. Exposure at 42.5 degrees C for 30 min resulted in more than 95% inhibition of NK activity. Conjugate-formation assays revealed that the mechanisms of hyperthermic NK inactivation are associated with post-binding lytic events. However, hyperthermia treated NK cells could partially recover their cytotoxic activity. Unheated lung lymphocytes (LL) were more sensitive to hyperthermic inhibition than spleen (SL) and blood (PBL) lymphocytes but they were also able to recover to a greater extent from such inactivation. Moreover, the responsiveness of NK cells from lung, blood and spleen to interleukin-2 (IL-2) and interferon (IFN-alpha/beta) was altered differently by heat shock. Hyperthermia treatment increased the ability of NK cells from blood to respond to IL-2 or IFN-alpha/beta. Similarly hyperthermia treated NK cells from spleen were more responsive to IFN-alpha/beta. By contrast such treatment did not change significantly the responsiveness of lung NK cells to these agents. Taken together, our findings indicate that NK cells from various compartments behave differently in response to hyperthermia treatment. Moreover, it suggests that hyperthermia treatment does not irreversibly comprise the host natural killer response and may even in some cases increase NK cell responsiveness to biological response modifiers (BRM).

Modulation of lung-associated natural killer activity by resident and activated alveolar macrophages

Alveolar macrophages (AM) freshly obtained by bronchoalveolar lavage suppressed significantly, in a dose-dependent fashion, lung interstitial lymphocytes cytotoxicity against the NK-sensitive target cells, YAC-1. Kinetic experiments revealed that AM-mediated suppression of NK activity was seen following short-term incubation of AM with lymphocytes (4 h) and was unchanged after a 24 h co-culture period. Freshly obtained lung lymphocytes and lymphocytes incubated for 24 h were similarly inhibited by AM. In addition, incubation of AM for 24 h did not abrogate their suppressive effect on lung NK activity. Interestingly, AM-conditioned media, also caused a significant inhibition of lung NK activity. Furthermore, in vitro activation of AM with lipopolysaccharide (LPS, 5 micrograms/ml) and muramyl dipeptide (MDP, 20 micrograms/ml) significantly enhanced the inhibitory effect of AM on lung NK activity. Similarly, in vivo activation of AM locally by intratracheal instillation of attapulgite, an inflammatory agent, resulted in greater AM-mediated down regulation. Taken together, these data indicate that lung NK activity is modulated by locally derived factors and suggest that pharmacologic manipulation of AM may play a determining role in the activation of lung NK activity by biological response modifiers (BRM).

Interactions between alveolar macrophage subpopulations modulate their migratory function

To better understand the mechanisms by which alveolar macrophages (AM) are attracted to local sites in the lung, the locomotion of AM in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP) was investigated. Total bronchoalveolar cells (99% AM) obtained by a nondiscriminating bronchoalveolar lavage procedure migrated toward FMLP over a range of concentrations of 10(-12) M to 10(-6) M. Dose-response experiments showed a biphasic response with two peaks of migration obtained respectively at 5 x 10(-10) M and 10(-8) M. Analysis in the presence and absence of a positive gradient of FMLP revealed that the first peak of migration (5 x 10(-10) M FMLP) corresponded predominantly to chemotactic activity whereas the second peak of migration (10(-8) M FMLP) was associated with chemokinetic activity. To further evaluate these activities of oriented (chemotaxis) vs. random (chemokinesis) migration, AM were separated into two fractions by a two-step bronchoalveolar lavage procedure. Whereas fraction 1 displayed exclusively chemokinesis in response to higher concentrations of FMLP (10(-8) M), fraction 2 was totally unresponsive to FMLP over a wide range of concentrations (5 x 10(-11) M - 10(-7) M). When both fractions were combined, however, the chemotactic response to low concentrations of FMLP (5 x 10(-10) M) was restored. Additional analysis of these two AM fractions indicated that fraction 1 AM had a significantly lower degree of adherence and aggregation than fraction 2 AM. These data suggest that cell-cell cooperation is important for AM chemotactic response to FMLP and that such interaction may involve changes in adherence and aggregation.

Neurotensin enhances IL-1 production by activated alveolar macrophages

Peptides may play a physiologic role in regulating immune responses and in triggering a variety of cellular events that modify the sensitivity of cells in the periphery. Neurotensin (NT) is present in the lung and it has been shown to bind to mouse peritoneal macrophages and influence their phagocytic ability. In this study, the effect of NT on the production of IL-1 by rat alveolar macrophages (AM) has been investigated. Although NT did not stimulate the release of IL-1 or increase the apparent intracellular pool of IL-1 when incubated with AM, there was significant cell changes, such as increased adherence, spreading, and altered shape. Furthermore, when AM were stimulated with LPS, both the intracellular and extracellular pools of IL-1 were significantly increased by NT. This effect was dose dependent and was observed at concentrations ranging from 10(-11) to 10(-6) M. NT did not modify the kinetics of LPS-induced IL-1 release nor the effects of a given suboptimal concentration of LPS. The release of IL-1 by various inducers, including muramyl dipeptide (MDP) and zymosan was also enhanced by NT, suggesting a general modulator role for this neuropeptide. When NT was added concomitantly with other potentiators of IL-1 production, such as IFN-gamma and leukotriene B4, no synergistic effect on IL-1 release was seen. Kinetics experiments showed that optimal enhancement of IL-1 production occurred when AM cultures were preincubated with NT before addition of MDP or when NT and MDP were present together at the initiation of the 24-h AM cultures. Taken together, our data suggest that NT acts early in the induction process of IL-1. Because IL-1 plays an important role both in the initiation of the immune response and in the local manifestations of inflammation, NT released in the vicinity of pulmonary blood vessels and the respiratory epithelium may modulate immunologically relevant responses in the lung microenvironment.

Neurotensin enhances IL-1 production by activated alveolar macrophages

Peptides may play a physiologic role in regulating immune responses and in triggering a variety of cellular events that modify the sensitivity of cells in the periphery. Neurotensin (NT) is present in the lung and it has been shown to bind to mouse peritoneal macrophages and influence their phagocytic ability. In this study, the effect of NT on the production of IL-1 by rat alveolar macrophages (AM) has been investigated. Although NT did not stimulate the release of IL-1 or increase the apparent intracellular pool of IL-1 when incubated with AM, there was significant cell changes, such as increased adherence, spreading, and altered shape. Furthermore, when AM were stimulated with LPS, both the intracellular and extracellular pools of IL-1 were significantly increased by NT. This effect was dose dependent and was observed at concentrations ranging from 10(-11) to 10(-6) M. NT did not modify the kinetics of LPS-induced IL-1 release nor the effects of a given suboptimal concentration of LPS. The release of IL-1 by various inducers, including muramyl dipeptide (MDP) and zymosan was also enhanced by NT, suggesting a general modulator role for this neuropeptide. When NT was added concomitantly with other potentiators of IL-1 production, such as IFN-gamma and leukotriene B4, no synergistic effect on IL-1 release was seen. Kinetics experiments showed that optimal enhancement of IL-1 production occurred when AM cultures were preincubated with NT before addition of MDP or when NT and MDP were present together at the initiation of the 24-h AM cultures. Taken together, our data suggest that NT acts early in the induction process of IL-1. Because IL-1 plays an important role both in the initiation of the immune response and in the local manifestations of inflammation, NT released in the vicinity of pulmonary blood vessels and the respiratory epithelium may modulate immunologically relevant responses in the lung microenvironment.

Changes in autacoid and neuropeptide contents of lung cells in asbestos-induced pulmonary fibrosis

The purpose of this study was to determine if asbestos-induced pulmonary fibrosis in the rat can affect the levels of autacoids and peptides in freshly isolated lung cells. Lung fibrosis was experimentally induced in rats by a single intratracheal instillation of 5 mg UICC Canadian chrysotile B fibers. Isolated lung cells were prepared from normal and from asbestos-exposed rats. These cells were also fractionated on bovine serum albumin (BSA) gradients. The contents of serotonin (5-HT), histamine (HIST), vasoactive intestinal peptide (VIP), and bombesin (BN) were measured in isolated total cell preparations as well as in density-fractionated cell populations from normal and from asbestos-exposed rats. Analysis of total lung cell preparation showed the presence of heterogeneous populations in normal rat lung. After asbestos exposure, there were significant changes in these cell populations as evidenced by significant increases in lymphocyte and mast cell numbers. In addition, increased levels of 5-HT, HIST, and VIP were observed in isolated lung cells obtained from rats exposed to asbestos 1, 3, and 6 months after instillation. BN content was unchanged 3 months after treatment, but was significantly increased at the 6 month-interval, suggesting a different pattern of response for this neuropeptide. Density fractionation of various cell populations further showed selective changes in specific cell fractions of lung after asbestos exposure. At 6 months, increased levels of 5-HT, HIST, and VIP were associated with cell fraction 7, whereas changes in BN content were found in cell fractions 2 and 3. Similarly, there was a significant increase of mast cells in fraction 7 at the 6-month interval.(ABSTRACT TRUNCATED AT 250 WORDS)

Asbestos-induced fibrosis in rats: increase in lung mast cells and autacoid contents

Adult male Wistar rats were treated with one tracheal instillation of 5 or 10 mg chrysotile B asbestos fibers in 0.5 ml saline, or 0.5 ml saline only (controls). Rats were killed at 1, 3, and 6 months postinstillation. Serotonin and histamine were quantitated in lung tissue homogenate using high-performance liquid chromatography with electrochemical and fluorometric detection, respectively. Serotonin was also quantitated in the cytoplasm of grouped (NEB) and individual (NEC) neuroendocrine cells and in mast cells using formaldehyde vapor-induced fluorescence and microspectrofluorometry, and density indices of NEBs, NECs, and mast cells were determined. Tissue edema, fibrotic lesions, and medial hypertrophy of pulmonary arterioles were assessed morphometrically. Test rats had higher pulmonary serotonin and histamine levels than controls at 1, 3, and 6 months. They also had higher cellular serotonin in NEBs at 1 month, but not in NECs, and tended to have higher serotonin levels in mast cells at 6 months. Mast cell numbers were higher among tests at 1 and 3 months, whereas NEBs and NECs were unchanged by asbestos. There was no difference between tests and controls in the amount of tissue edema at any time. However, all test rats had distinct lung lesions characterized by peribronchiolar fibrosis and bronchiolitis obliterans. No such lesions were present among control rats. Typically, mast cells were located immediately beneath the epithelial basal lamina of the bronchiolar fibrotic projections and at their stalks, whereas no mast cells were noted beneath normal epithelium, indicating a role of mast cells in asbestos-induced peribronchiolar fibrosis. Moreover, arteriolar medial hypertrophy at all three ages in conjunction with the increased levels of serotonin was an index of putative chronic pulmonary hypertension. Our results suggest that asbestos-induced rises in serotonin and histamine are due primarily to increased numbers of mast cells.

Immunoregulation of lung fibroblast growth: alteration in asbestos-induced pulmonary fibrosis

Initial studies on mononuclear cell-fibroblast interactions have shown that stimulated human lymphocytes produced a fibroblast growth inhibitory factor and that asbestos, a fibrogenic dust, interferes with this process in vitro. To investigate the role of these interactions in pathologies characterized by pulmonary fibrosis, we used a rat model of asbestos-induced fibrosis. Rats received a single intratracheal instillation of either saline or 10 mg of chrysotile asbestos fibres. Three months after treatment, peripheral blood mononuclear leucocytes (PBML) supernatant fractions were prepared and their effects on lung fibroblast growth measured. As for human PBML, rat PBML stimulated with Concanavalin A (Con A) produced 24 h after initiation of the cultures a soluble factor which inhibits lung fibroblast DNA synthesis and growth in a dose-dependent fashion. By contrast, Con A-stimulated PBML from rats exposed to asbestos failed to produce significant levels of fibroblast growth inhibitory activity. No significant change of total PBML number or in the proportion of circulating mononuclear cell populations was observed. Furthermore, upon stimulation with lipopolysaccharide (LPS), monocytes from asbestotic animals retained their capacity to produce interleukin (IL-1), a mediator required for lymphokine production. Our study demonstrates that suppression of FGIF production by circulating PBML occurs in animals with lung fibrosis and suggests that mechanisms other than impairment of IL-1 production may be responsible for the suppressive effect of asbestos on the production of such fibroblast regulatory lymphokine.

Cytokine regulation of lung fibroblast proliferation. Pulmonary and systemic changes in asbestos-induced pulmonary fibrosis

A complex series of interactions between immunocompetent cells and fibroblasts exists. Because pulmonary fibrosis may result from an increased number of collagen-producing fibroblasts, we studied the production of fibroblast growth factors derived from alveolar macrophages (AM) and peripheral blood mononuclear leukocytes (PBML) during the development of asbestos-induced fibrosis. Three groups of rats received, respectively, a single intratracheal injection of saline (control), 5 mg of asbestos, and 10 mg of asbestos. Bronchoalveolar lavage (BAL) and PBML isolation were performed on each animal 1, 3, and 6 months after instillation. Differential cell analyses revealed no significant change in the BAL cell populations except for a small but significant increase in the proportion of lymphocytes in the 10-mg group at 1 month and in both asbestos groups at 3 months. Similar analyses of PBML revealed only a small reduction in total PBML in the 10-mg group at 6 months. Bronchoalveolar cells (98% AM) from control rats spontaneously released a fibroblast growth factor (FGF), whereas Con-A-stimulated PBML of the same animals produced fibroblast growth inhibitory activity (FGIF). One month after asbestos exposure, when fibrotic lesions were apparent, AM production of FGF was significantly enhanced, and such increase persisted for as long as 6 months. By contrast, no significant change in FGIF production by Con-A-stimulated PBML was seen at the 1-month interval. However, 3 months after exposure, there was a significant suppression of FGIF production by PBML from rats in the 10-mg group and at 6 months by PBML from rats in both asbestos groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of interleukin 2 and interferon gamma production by leukotriene B4 in human lymphocyte cultures

Interleukin 2 (IL-2) and interferon-gamma (IFN) production by human lymphocytes was significantly enhanced in the presence of leukotriene B4 (LTB4) and indomethacin. Depletion of the T8+ suppressor cell subset of human T cells resulted in enhanced lymphokine production and further augmentation by LTB4. These findings suggest that LTB4 can regulate immune responses through its modulation of lymphokine production.

Effects of chrysotile asbestos on DNA synthesis and growth of human embryonic lung fibroblasts

The in vitro effects of asbestos fibers on thymidine (TdR3H) incorporation and growth of lung fibroblasts have been studied. Incubation of human embryonic lung fibroblasts with UICC Chrysotile B asbestos for 48 hr caused a 3 to 5-fold increase of TdR3H incorporation as compared with control cultures. This increase was dose-dependent with optimal effect obtained with doses as low as 10 micrograms/ml and with cell density of 5 X 10(4) fibroblasts per culture. However, enhanced TdR3H incorporation in treated cells was not correlated with an overall increase of the fibroblast population compared with control cultures as evidenced by cell counts and microscopic examination. Fibroblasts exposed to relatively low concentrations of UICC chrysotile (5-10 micrograms/ml) displayed an initial decrease in cell number compared to controls during the first 24 hr of incubation. At 48 hr however, enhanced TdR3H incorporation occurred with a concomittant increase in cell number. Moreover, continuous exposure of fibroblast cultures to chrysotile (10 micrograms/ml) for a longer period of time led to sustained increase of TdR3H incorporation and resumption of cell proliferation. It is suggested that increased thymidine incorporation is directly related to the effectiveness of asbestos in inhibiting the growth of lung fibroblasts and that measurement of TdR3H incorporation may represent a sensitive means of assessing rapidly the biological activity of asbestos. The possible relevance of this activity to asbestos-induced fibrogenesis and tumorigenesis is also discussed.

Alveolar macrophage stimulation of lung fibroblast growth in asbestos-induced pulmonary fibrosis

Asbestotic lesions are characterized by macrophagic accumulation, fibroblast proliferation, and collagen deposition. To evaluate the potential involvement of alveolar macrophages in the subsequent fibrogenic reaction, the authors studied the effects of macrophages from normal and asbestos-treated rats upon lung fibroblast proliferation in vitro. Culture supernatants from bronchoalveolar (BAL) cells (99% macrophages) of normal rats stimulated lung fibroblast DNA synthesis and growth in a dose-dependent manner. Fibroblast growth factor (FGF) release by alveolar macrophages (AMs) was rapid (within 1 hour of incubation) and dependent on the number of AMs in culture. Moreover, culture supernatants from BAL cells of animals exposed to asbestos (single intratracheal injection) stimulated fibroblast proliferation to a greater degree than culture supernatants from BAL cells of control animals. Enhanced FGF production occurred 1 week after asbestos instillation and persisted up to 24 weeks. This change was accompanied in the early stages (1-4 weeks) by an increase in the total number of BAL cells which returned to control values by 12 weeks. Differential analysis of BAL cell populations showed a transient infiltration of neutrophils in the bronchoalveolar compartment followed by a significant accumulation of macrophages which persisted up to 1 month. Furthermore, lungs of asbestos-treated animals showed evidence of pathologic alterations characterized by fibroblast proliferation and collagen deposition. This study demonstrates that increased production of fibroblast growth factor by alveolar macrophages in vitro coincides with the development of asbestos-induced fibrosis. Prolonged stimulation of FGF release may contribute to excessive fibroblast proliferation and fibrosis.

Leukotrienes augment interleukin 1 production by human monocytes

The effects of leukotrienes (LT) on production of interleukin 1 (IL 1) by human peripheral blood monocytes were examined. LTB4 enhanced IL 1 production by lipopolysaccharide (LPS)-stimulated monocytes twofold to threefold, and the most efficient concentrations of LTB4 were 10(-8) to 10(-7) M. LTD4 also enhanced IL 1 production, but to a lesser extent than LTB4. Adherence-purified, but otherwise unstimulated, human monocytes could also be induced to produce IL 1 in response to LTB4. Similarly, IL 1 production by monocytes stimulated with the known IL 1 inducers muramyl dipeptide, silica, or zymosan was also enhanced by LTB4. Inhibition of cyclooxygenase with use of indomethacin during IL 1 production by LPS-treated monocytes enhanced thymocyte response to IL 1, but LTB4 further enhanced IL 1 production when added to indomethacin-treated monocyte cultures. Neither LTB4 nor indomethacin had any direct effect on thymocyte proliferation. Optimal enhancement of IL 1 production occurred when LPS and LTB4 were present together at the initiation of the 24-hr monocyte culture. Significant enhancement was also observed, however, when monocyte cultures were either preincubated with LTB4 before addition of LPS or cultured with LPS alone for 3 hr before addition of LTB4. These results indicate that leukotrienes can modulate IL 1 production by human monocytes and suggest that they may play a role in IL 1-mediated functions of monocytes in inflammatory and immune reactions.

Leukotrienes augment interleukin 1 production by human monocytes

The effects of leukotrienes (LT) on production of interleukin 1 (IL 1) by human peripheral blood monocytes were examined. LTB4 enhanced IL 1 production by lipopolysaccharide (LPS)-stimulated monocytes twofold to threefold, and the most efficient concentrations of LTB4 were 10(-8) to 10(-7) M. LTD4 also enhanced IL 1 production, but to a lesser extent than LTB4. Adherence-purified, but otherwise unstimulated, human monocytes could also be induced to produce IL 1 in response to LTB4. Similarly, IL 1 production by monocytes stimulated with the known IL 1 inducers muramyl dipeptide, silica, or zymosan was also enhanced by LTB4. Inhibition of cyclooxygenase with use of indomethacin during IL 1 production by LPS-treated monocytes enhanced thymocyte response to IL 1, but LTB4 further enhanced IL 1 production when added to indomethacin-treated monocyte cultures. Neither LTB4 nor indomethacin had any direct effect on thymocyte proliferation. Optimal enhancement of IL 1 production occurred when LPS and LTB4 were present together at the initiation of the 24-hr monocyte culture. Significant enhancement was also observed, however, when monocyte cultures were either preincubated with LTB4 before addition of LPS or cultured with LPS alone for 3 hr before addition of LTB4. These results indicate that leukotrienes can modulate IL 1 production by human monocytes and suggest that they may play a role in IL 1-mediated functions of monocytes in inflammatory and immune reactions.

Characterization of the bronchoalveolar cellular response in experimental asbestosis. Different reactions depending on the fibrogenic potential

Analysis of bronchoalveolar cell types and structure was performed during the development of asbestos-induced lung injury in the rat. Animals received single intratracheal injections of one of the following: saline (control), UICC chrysotile B asbestos (5 mg), or very short 4T30 chrysotile fibers (5 mg). Bronchoalveolar lavage (BAL) was performed at various intervals after instillation. Analysis of BAL fluid showed significant increase in inflammatory cells in response to asbestos, which persisted longer in animals treated with chrysotile B. Presence of numerous mitotic figures in BAL fluid of treated animals suggests that macrophage replication may contribute in part to this response. Differential cellular analysis indicated that after injection of long chrysotile fibers, which causes fibrotic lesions within 7 days, polymorphonuclear leukocytes (PMN) appear as early as Day 1 in significant concentration (40%) in the bronchoalveolar compartment and persist through Day 7 after treatment. From Day 7 to Day 21, multinucleated cells (MGC) were found in lavage fluid (5 to 8%). Most of these cells were binucleated, and none had more than 3 nuclei. By contrast, exposure to very short chrysotile fibers caused only a very transient influx of PMN on Day 1. By Day 7, there was a significant increase in MGC, which persisted through Day 21, at which time no fibrosis was apparent. Although most of these cells were binucleated, many cells had 3 or more nuclei. The giant cells were predominantly of the foreign body type, with MGC of the Langhans type also present.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary bombesin in experimentally induced asbestosis in rats

The pulmonary levels of immunoreactive bombesin in normal rat lungs and rat lungs exposed to asbestos were determined. Experimental asbestosis was induced in rats by a single intratracheal injection of 5 mg or 10 mg UICC standard Canadian Chrysotile B while sham-operated control rats received only the saline carrier. At 1, 3, 6, and 9 months following instillation, 5 animals of each group were sacrificed and the lungs removed. A section was kept for morphologic analysis, while the remaining portion was submitted to acid extraction and later measured for bombesin content by radioimmunoassay (RIA). The Chrysotile B-exposed tissues displayed the characteristic features typical of the fibrotic state associated with asbestosis one month following exposure and thereafter. The pulmonary bombesinlike immunoreactivity ranged from 4.5-7.5 pmoles/g tissue in normal rat lung, and these levels remained unchanged at 1 and 3 months after asbestos exposure. However at 6 and 9 months, significant increases ranging between 2 and 2.5 fold were observed. The initial increases in bombesin levels occurred at a later time (6 months) than those already observed for vasoactive intestinal peptide (VIP) (3 months). However, VIP levels plateaued at 9 months, while those of bombesin were still increasing. High-pressure liquid chromatography (HPLC) coupled with RIA demonstrates the presence of two bombesin-immunoreactive peaks in normal rat lung, the major one coeluting with the mammalian bombesinlike peptide gastrin-releasing peptide (GRP) and the other one being presumably a C-terminal portion of GRP. These data indicate that immunoreactive bombesin and VIP are selectively increased at different times following asbestos instillation and that these changes occur after the onset of fibrosis and the appearance of well-defined fibrotic lesions.

Collagenolytic activity from circulating polymorphonuclear leucocytes of patients with asbestosis

Levels of collagenolytic activity produced by circulating polymorphonuclear leucocytes (PMN) of patients exposed to asbestos and patients with asbestosis were found to be similar to those of normal controls.

Asbestos-related increase in pulmonary levels of vasoactive intestinal peptide (VIP)

Vasoactive intestinal peptide (VIP), leucine-enkephalin (Leu-Enk), dynorphin (Dyn), neurotensin (NT) and substance P (SP) were measured by radioimmunoassay in lung and bronchoalveolar lavage (BAL) fluids of sham operated control rats and rats exposed to asbestos (5 and 10 mg, single intratracheal injections) for 3 and 6 months. Among these peptides, VIP, Leu-Enk and Dyn were the most abundant with 6 to 25 pmoles per g of lung tissue as compared with 0.95 to 1.2 pmoles per g for the other neuropeptides. In the presence of asbestos, VIP levels were selectively increased up to 2.7 times in lung tissue and 4.3 times in BAL fluids. On high pressure liquid chromatography (HPLC), the immunoreactive VIP coeluted with synthetic VIP. It is concluded that this selective increase may be involved in the pathogenesis of asbestos-related diseases. Exposure to asbestos causes chronic inflammatory reactions in the lung which may lead to fibrosis (1) and increase the incidence of pleuropulmonary cancers (2). Little is known concerning the biochemical changes responsible for the deleterious effects of asbestos on pulmonary functions. Previous studies have documented the vast complexity and diversity of lung biochemistry including its ability to metabolize lipids, inactivate certain enzymes and produce physiologically active amines (3-6). Recently, the lung has been recognized as an important source of peptidergic substances. VIP and SP were reported to be localized in nerve terminals of the main airways and in axons of the parasympathetic conducts (7-11). Other neuropeptides including bombesin (12, 13), calcitonin (13, 14) and Leu-Enk (13) were also detected in the lung. However, these latter peptides were mainly confined to diffuse granule-containing cells also known as APUD cells (amine precursor uptake and decarboxylation cells) (15). The role of these neuropeptides in normal lung function and in pulmonary diseases is unknown. However, it has recently been demonstrated that APUD cells proliferate in the rat lung following asbestos inhalation (16) and lung exposure to carcinogens (17, 18). In addition, Moody et al. (19) and Sorenson et al. (20) have observed high levels of bombesin in human cell lines derived from small-cell lung carcinoma. It was then of particular interest to verify if lung exposure to asbestos can induce some changes in the levels of various neuropeptides. In the present study, we report that VIP is significantly increased in the lungs and BAL fluids of rats exposed to asbestos while no significant change in the levels of Leu-Enk, Dyn, NT and SP is observed.

In vitro suppression of fibroblast growth inhibitory lymphokine production by asbestos

Human peripheral blood mononuclear leucocytes (PBML) stimulated with concanavalin A (Con A) or phytohaemagglutinin (PHA) produced a soluble factor which inhibits lung fibroblast DNA synthesis and growth. Lymphocyte enriched preparations produced significant growth inhibitory activity in the presence of PHA whereas media from adherent mononuclear cells incubated in the presence of the mitogen did not contain similar activity. This fibroblast growth inhibitory factor (FGIF) was non-dialysable, heat stable and resistant to pH 5. FGIF was also resistant to treatment with chymotrypsin and phosphodiesterase but partially sensitive to treatment with trypsin. Interestingly, there was significant suppression of FGIF production by PBML cultured with PHA in the presence of low concentrations of chrysotile asbestos (5-25 micrograms/ml). In this regard, asbestos (25 micrograms/ml) was not cytotoxic for lymphocytes but had a damaging effect on monocytes as evidenced by the release of lactate dehydrogenase (LDH) a cytoplasmic enzyme, in their culture media. These findings indicate that stimulated lymphocytes have the ability to inhibit fibroblast proliferation by releasing FGIF and that asbestos interfere with this process. Thus, while FGIF may regulate the extent of connective tissue proliferation during normal repair process, suppression of its production by asbestos may contribute to excessive fibroblast accumulation and fibrosis.