Expression of a tumor necrosis factor-alpha transgene in murine lung causes lymphocytic and fibrosing alveolitis. A mouse model of progressive pulmonary fibrosis

Analysis of tumor necrosis factor-alpha, lymphotoxin-alpha, tumor necrosis factor receptor II, and interleukin-6 polymorphisms in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by chronic inflammation that is associated with structural damage of the lung and fibrosis. Although the etiology of IPF is unknown, it is likely to involve an interaction between environmental and multiple genetic components. Animal models of pulmonary fibrosis have shown that proinflammatory mediators are critical at both the inflammatory and fibrotic stages of the disease. Genetic variants exist in genes encoding proinflammatory mediators, as well as in genes encoding their receptors, which makes these genes candidates for the pathogenesis of IPF. In the present study, we examined 12 biallelic polymorphisms in the genes for tumor necrosis factor (TNF)-alpha (+488[G/A], -238[G/A], -308[G/A]), lymphotoxin (LT)-alpha (+720[C/A], +365[C/G], and +249[A/G], determining haplotypes LT-alpha1 to LT-alpha4), tumor necrosis factor-receptor 2 (TNF-RII) (gb:M32315: 676[T/G], 1663[A/G], 1668[T/G], 1690[C/T]), and interleukin- (IL)-6 (promoter -174[G/C], intron 4[A/G]). We also examined the haplotypes determined by the three biallelic polymorphisms in each of the TNF-alpha and LT-alpha genes. As compared with a normal control population, the IPF group showed no significant deviations in genotype, allele, or haplotype frequencies. Surprisingly, in the IPF population, but not in the control population, an increased frequency of cocarriage of the IL-6 intron 4G and the TNF-RII 1690C alleles was observed, despite the location of the two genes on different chromosomes. Moreover, using impairment of carbon monoxide transfer (DL(CO)) adjusted for duration of dyspnea as a marker of rapidity of disease progression, we found that the IL-6 intron 4GG genotype was the only genotype independently associated with lower DL(CO) levels. These findings, if independently confirmed, will be the first to suggest that disease progression in IPF may be linked to a particular genetic marker or to functional polymorphisms in other genes near that marker.

Evidence for epigenetic mechanisms that silence both basal and immune-stimulated transcription of the IL-8 gene

It is becoming increasingly clear that epigenetic silencing of gene transcription plays a critical role in the regulation of gene expression in many biological processes. Tight regulation of immunomodulatory substances that are important for the initiation of the inflammatory cascade, such as chemoattractive cytokines, is essential to prevent initiation of unrestrained immune activation. Using the Caco-2 intestinal cell line as a model, we reveal two distinctly different mechanisms by which the gene for the neutrophil chemoattractive cytokine IL-8 is silenced. Nuclear run-on studies, as well as stably transfected reporter and marked minigene constructs, demonstrate that cellular differentiation inhibits immune-activated transcription of the IL-8 gene, a mechanism that is dependent on histone deacetylase activity. Unexpectedly, this silencing mechanism does not involve previously described regulatory elements in the IL-8 promoter but rather cis-acting regions located at a distance from the IL-8 gene locus. Genomic elements distant to the immediate IL-8 locus are also required to silence aberrant basal transcriptional activity of the IL-8 promoter in the absence of immune activation. However, in this case, silencing occurs in a histone deacetylase-independent fashion. These findings were confirmed in transgenic mice in which, in the absence of these elements, aberrant IL-8 gene activity was present primarily in the intestinal tract. Epigenetic silencing of cytokine gene transcription through distant genomic elements is an important level of gene regulation that may be relevant to the pathogenesis of immunologic disease states.

A new function of green tea: prevention of lifestyle-related diseases

In the normal human life span, there occur lifestyle-related diseases that may be preventable with nontoxic agents. This paper deals with the preventive activity of green tea in some lifestyle-related diseases. Green tea is one of the most practical cancer preventives, as we have shown in various in vitro and in vivo experiments, along with epidemiological studies. Among various biological effects of green tea, we have focused on its inhibitory effect on TNF-alpha gene expression mediated through inhibition of NF-kappaB and AP-1 activation. Based on our recent results with TNF-alpha-deficient mice, TNF-alpha is an endogenous tumor promoter. TNF-alpha is also known to be a central mediator in chronic inflammatory diseases such as rheumatoid arthritis and multiple sclerosis. We therefore hypothesized that green tea might be a preventive agent for chronic inflammatory diseases. To test this hypothesis, TNF-alpha transgenic mice, which overexpress TNF-alpha only in the lungs, were examined. The TNF-alpha transgenic mouse is an animal model of human idiopathic pulmonary fibrosis which also frequently develops lung cancer. Expressions of TNF-alpha and IL-6 were inhibited in the lungs of these mice after treatment with green tea in drinking water for 4 months. In addition, judging from the results of a prospective cohort study in Saitama Prefecture, Japan, green tea helps to prevent cardiovascular disease. In this study, a decreased relative risk of death from cardiovascular disease was found for people consuming over 10 cups of green tea a day, and green tea also had life-prolonging effects on cumulative survival. These data suggest that green tea has preventive effects on both chronic inflammatory diseases and lifestyle-related diseases (including cardiovascular disease and cancer), resulting in prolongation of life span.

Association of tumor necrosis factor-alpha and interleukin-1 gene polymorphisms with silicosis

Silicosis, an interstitial lung disease prevalent among miners, sand blasters, and quarry workers, is manifested as a chronic inflammatory response leading to severe pulmonary fibrotic changes. Proinflammatory cytokines, such as TNFalpha and IL-1, produced in the lung by type II epithelial cells and alveolar macrophages, have been strongly implicated in the formation of these lesions. Recently, a number of single nucleotide polymorphisms (SNPs), which quantitatively affect mRNA synthesis, have been identified in the TNFalpha promoter and IL-1 gene cluster and their frequency is associated with certain chronic inflammatory diseases. To assess the role of these SNPs in silicosis, we examined their frequency in 325 ex-miners with moderate and severe silicosis and 164 miners with no lung disease. The odds ratio of disease for carriers of the minor variant, TNFalpha (-238), was markedly higher for severe silicosis (4.0) and significantly lower for moderate silicosis (0.52). Regardless of disease severity, the odds ratios of disease for carriers of the IL-1RA (+2018) or TNFalpha (-308) variants were elevated. There were no significant consistent differences in the distribution of the IL-1alpha (+4845) or IL-1beta (+3953) variants with respect to disease status. In addition, several significant gene-gene and gene-gene-environment interactions were observed. Different associations between moderate cases and controls versus severe cases and controls were also observed in a number of these multigene comparisons. These studies suggest that gene-environment interactions involving cytokine polymorphisms play a significant role in silicosis by modifying the extent of and susceptibility to disease.

FTS reduces bleomycin-induced cytokine and chemokine production and inhibits pulmonary fibrosis in mice

Bleomycin (BLM), an antitumour drug, is known to cause interstitial pneumonia followed by pulmonary fibrosis, and has often been used to produce an animal model of pulmonary fibrosis. In the present study, we examined the effect of a nonapeptide thymic hormone, facteur thymique serique (FTS), on the murine lung fibrosis induced by intratracheal instillation of BLM. Treatment with FTS ameliorated BLM-induced fibrotic changes in a dose-dependent manner, as indicated by the reduced accumulation of hydroxyproline (HP). In addition, FTS suppressed BLM-induced cellular inflammatory response in the lungs, as evidenced by inhibition of increased lung weight, reduced accumulation of inflammatory leucocytes, including lymphocytes and neutrophils, but not macrophages, and less pronounced histopathological changes. Finally, BLM challenge increased the local synthesis of proinflammatory cytokines, TNF-alpha and IL-1beta and chemokines, MCP-1, MIP-1alpha RANTES, MIP-2 and KC, while administration of FTS suppressed the production of these cytokines, except for MCP-1. These effects of FTS were observed only when mice received intratracheal instillation with BLM. Considered collectively, our results indicated that FTS treatment ameliorated the cellular inflammatory responses and fibrotic changes in the lungs caused by BLM and such inhibition was well correlated with reduced synthesis of several fibrosis-related cytokines, and suggested that FTS may be potentially useful for the treatment of pulmonary fibrosis.

Idiopathic pneumonia syndrome after bone marrow transplantation: the role of pre-transplant radiation conditioning and local cytokine dysregulation in promoting lung inflammation and fibrosis

Pulmonary complications and graft-vs.-host disease (GVHD) remain severe threats to survival after bone marrow transplantation (BMT). Idiopathic pneumonia syndrome (IPS) accounts for nearly 50% of all the cases of interstitial pneumonitis after BMT. IPS is characterized by an early inflammatory phase followed by chronic inflammation and fibrosis of lung tissue; however, the immunopathogenesis of this disease is not yet clearly understood. This biphasic syndrome has been reported to be associated with pre-transplant radiation conditioning in some studies while others have suggested that GVHD or autoimmune phenomena may be responsible for its development. The early post-BMT phase is characterized by the presence of inflammatory cytokines whose net effect is to promote lymphocyte influx into lungs with minimal fibrosis, that leads to an acute form of graft-vs.-host reaction-mediated pulmonary tissue damage. Gradual changes over time in leucocyte influx and activation lead to dysregulated wound repair mechanisms resulting from the shift in the balance of cytokines that promote fibrosis. Using data from new animal models of IPS and information from studies of human IPS, we hypothesize that cytokine-modulated immunological mechanisms which occur during the acute and chronic phases after bone marrow transplantation lead to the development of the progressive, inflammatory, and fibrotic lung disease typical of idiopathic pneumonia syndrome.

Intra-amniotic endotoxin: chorioamnionitis precedes lung maturation in preterm lambs

The inflammatory and lung maturational effects of intra-amniotic exposure to endotoxin were assessed in fetal lambs. Five hours to 25 days after intra-amniotic injection of endotoxin, preterm lambs were delivered at 119-125 days gestation. Intra-amniotic endotoxin caused an inflammatory cell infiltration in amnion/chorion at 5 h, which persisted for 25 days. At 5-15 h after endotoxin, amnion/chorion cytokine mRNAs increased [12- to 26-fold for interleukin (IL)-1beta, IL-6, and IL-8 mRNA and 3-fold for tumor necrosis factor-alpha mRNA]. At 1-2 days after endotoxin, lung cytokine mRNAs increased 6- to 49-fold. Endotoxin caused modest changes in peripheral white blood cell counts and no significant cytokine mRNA responses in fetal liver, placenta, or jejunum. Lung maturation, as characterized by increased lung volumes and alveolar saturated phosphatidylcholine, occurred at 7 days and persisted for 25 days after endotoxin. We conclude that exposure to a single dose of intra-amniotic endotoxin causes inflammation and increases in cytokine mRNA in amnion/chorion and the fetal lung before lung maturation, consistent with the hypothesis that proinflammatory cytokines signal lung maturation.

Multiple courses of antenatal glucocorticoid treatment and fetal outcome

Thanks to the US National Institutes of Health Consensus Conference, the odds of antenatal use of glucocorticoids for preventing severe neonatal complications of premature delivery have significantly increased these last years. The belief that neonatal benefits last up to 7 days after the first course and administration of further courses is safe has led many obstetricians to prescribe multiple antenatal glucocorticoid courses. Whether multiple courses offer an advantage over a single course has not been demonstrated. In contrast, there are accumulating evidence suggesting that this practice may have short and long-term side effects. The potential benefits and side effects of multiple antenatal courses of glucocorticoids, extrapolated from experimental data and observational studies, are detailed in this review. Until the results of ongoing randomized trials with long term follow-up are available, the practice of giving multiple courses of glucocorticoids to women should be considered with the greatest caution.

Overexpression of tumor necrosis factor-alpha produces an increase in lung volumes and pulmonary hypertension

Tumor necrosis factor (TNF)-alpha is a key proinflammatory cytokine that is thought to be important in the development of pulmonary fibrosis, whereas its role in pulmonary emphysema has not been as thoroughly documented. In the present study, TNF-alpha was overexpressed in alveolar type II cells under the control of the human surfactant protein C promoter. In this report, we further characterized the pulmonary abnormalities and provided a physiological assessment of these mice. Histopathology of the lungs revealed chronic inflammation, severe alveolar air space enlargement and septal destruction, and bronchiolitis. However, pulmonary fibrosis was very limited and only seen in the subpleural, peribronchiolar, and perivascular regions. Physiological assessment showed an increase in lung volumes and a decrease in elastic recoil characteristic of emphysema; there was no evidence of restrictive lung disease characteristic of pulmonary fibrosis. In addition, the mice raised in ambient conditions in Denver developed pulmonary hypertension. Gelatinase activity was increased in the lavage fluid from these lungs. These results suggest that in these mice TNF-alpha contributed to the development of pulmonary emphysema through chronic lung inflammation and activation of the elastolytic enzymes but by itself was unable to produce significant pulmonary fibrosis.

Tumour necrosis factor-alpha production in fibrosing alveolitis is macrophage subset specific

BACKGROUND

Previous studies have revealed that tumour necrosis factor (TNF)-alpha is upregulated in fibrosing alveolitis (FA) in humans. The aim of this study was to compare the TNF-alpha secretory profile of alveolar macrophages (AMs) and peripheral blood monocytes (Mos) of patients with cryptogenic FA and systemic sclerosis (SSc), a rheumatological disorder in which lung fibrosis can occur. In particular, we wished to assess whether TNF-alpha levels differ between SSc patients with FA (FASSc) and a nonfibrotic group.

METHODS

The reverse haemolytic plaque assay was used to evaluate the secretion of cytokine at a single cell level while immunostaining allowed subtyping of AMs and Mos.

RESULTS

This study demonstrated a difference in total TNF-alpha levels produced by AMs when the levels in subjects with FA (cryptogenic FA and FASSc) were compared to levels in either SSc patients without FA (P = 0.0002) or normal healthy controls (P < 0.001). In addition, AMs from patients with FASSc secreted more TNF-alpha than those of patients with no FA (P = 0.003). In contrast, there were no significant differences in Mo TNF-alpha secretion between the groups. A positive correlation was found between total TNF-alpha level and number of neutrophils obtained by bronchoalveolar lavage from patients with FA (r = 0.49, P < 0.04). Finally, it was demonstrated that there was significant heterogeneity of TNF-alpha secretion and that a numerically significant subset of mononuclear phagocytes, RFD7, was responsible for more than 80% of TNF-alpha production.

CONCLUSION

By demonstrating the primary cell source of TNF-alpha in FASSc, more accurately targeted, possibly localized, anti-TNF strategies might be employed with success in the future.

Antenatal endotoxin and glucocorticoid effects on lung morphometry in preterm lambs

In utero inflammation may accelerate fetal lung maturation but may also play a role in the pathogenesis of chronic lung disease. We examined the impact of endotoxin, a potent proinflammatory stimulus, on structural and functional maturation of preterm sheep lungs. Date bred ewes received 20 mg Escherichia coli endotoxin or saline by ultrasound guided intra-amniotic injection at 119 d gestation. A comparison group of animals received 0.5 mg/kg betamethasone, a known maturational agent, at 118 d gestation. Lambs were delivered by cesarean section at 125 d (term = 150 d) and ventilated for 40 min. Lung function data are reported elsewhere. Total and differential white cell counts were performed on amniotic fluid and fetal lung fluid samples. Morphometric analyses were performed on inflation fixed right upper lobes. Total cell count increased slightly but not significantly in both amniotic fluid and fetal lung fluid. Both endotoxin and betamethasone had similar effects on alveolarization: average alveolar volume increased by approximately 20% and total alveolar number decreased by almost 30%. Both treatments led to thinning of alveolar walls, although this was statistically significant in the betamethasone-treated group only. Although antenatal endotoxin leads to striking improvements in postnatal lung function, this may be at the expense of normal alveolar development.

A critical role for alveolar macrophages in elicitation of pulmonary immune fibrosis

Hapten immune pulmonary interstitial fibrosis (HIPIF) is induced by a recall cell-mediated immune response against the hapten 2,4, 6-trinitrobenzene sulphonic acid (TNBS) in the lung. Studies here dissect the role of the cellular components of the bronchoalveolar lavage (BAL) cells (alveolar macrophages [AMs] versus monocytes and immature dendritic cells) in the fibrogenic inflammatory response. BAL cells from HIPIF mice were generally more activated and produced a greater amount of tumour necrosis factor-alpha (TNF-alpha) than controls. Liposome-encapsulated dichloromethylene diphosphonate (Cl(2)MDP) that was inoculated intranasally (i.n.) into mice selectively depleted AMs. Following AM depletion, the number of TNF-alpha-containing cells was reduced, and both the number of immune inflammatory cells recruited into the alveolar space and the subsequent collagen deposition (hydroxyproline) were decreased in the sensitized and intratracheally (i.t.) challenged mice. In conclusion, AMs are required, in part, for the development of pulmonary fibrosis in HIPIF because AM-derived factors such as TNF-alpha are needed for initiation of chemokine and cytokine pathways and accumulation of immune inflammatory cells.

Hyporesponsiveness of donor cells to lipopolysaccharide stimulation reduces the severity of experimental idiopathic pneumonia syndrome: potential role for a gut-lung axis of inflammation

Idiopathic pneumonia syndrome (IPS) is a major complication of allogeneic bone marrow transplantation (BMT). We have shown that experimental IPS is associated with increased levels of LPS and TNF-alpha in the bronchoalveolar lavage (BAL) fluid. We hypothesized that the deleterious effects of these inflammatory mediators in the lung may be linked to gut injury that develops after BMT. To test this hypothesis, we used mouse strains that differ in their sensitivity to LPS as donors in an experimental BMT model. Lethally irradiated C3FeB6F(1) hosts received BMT from either LPS-sensitive or LPS-resistant donors. Five weeks after BMT, LPS-resistant BMT recipients had significantly less lung injury compared with recipients of LPS-sensitive BMT. This effect was associated with reductions in TNF-alpha secretion (both in vitro and in vivo), BAL fluid LPS levels, and intestinal injury. The relationship between TNF-alpha, gut toxicity, and lung injury was examined further by direct cytokine blockade in vivo; systemic neutralization of TNF-alpha resulted in a significant reduction in gut histopathology, BAL fluid LPS levels, and pulmonary dysfunction compared with control-treated animals. We conclude that donor resistance to endotoxin reduces IPS in this model by decreasing the translocation of LPS across the intestinal border and systemic and pulmonary TNF-alpha production. These data demonstrate a potential etiologic link between gut and lung damage after BMT and suggest that methods that reduce inflammatory responses to LPS, and specifically, those that protect the integrity of the gut mucosa, may be effective in reducing IPS after BMT.

Surfactant components modulate fibroblast apoptosis and type I collagen and collagenase-1 expression

During lung injury, fibroblasts migrate into the alveolar spaces where they can be exposed to pulmonary surfactant. We examined the effects of Survanta and surfactant protein A (SP-A) on fibroblast growth and apoptosis and on type I collagen, collagenase-1, and tissue inhibitor of metalloproteinase (TIMP)-1 expression. Lung fibroblasts were treated with 100, 500, and 1,000 microg/ml of Survanta; 10, 50, and 100 microg/ml of SP-A; and 500 microg/ml of Survanta plus 50 microg/ml of SP-A. Growth rate was evaluated by a formazan-based chromogenic assay, apoptosis was evaluated by DNA end labeling and ELISA, and collagen, collagenase-1, and TIMP-1 were evaluated by Northern blotting. Survanta provoked fibroblast apoptosis, induced collagenase-1 expression, and decreased type I collagen affecting mRNA stability approximately 10-fold as assessed with the use of actinomycin D. Collagen synthesis and collagenase activity paralleled the gene expression results. SP-A increased collagen expression approximately 2-fold and had no effect on collagenase-1, TIMP-1, or growth rate. When fibroblasts were exposed to a combination of Survanta plus SP-A, the effects of Survanta were partially reversed. These findings suggest that surfactant lipids may protect against intraluminal fibrogenesis by inducing fibroblast apoptosis and decreasing collagen accumulation.

Lung development and function in preterm infants in the surfactant treatment era

Mortality of infants of < 1-kg birth weight has decreased because of surfactant treatments, antenatal glucocorticoid treatments, and new ventilation strategies. However, many of these infants develop a chronic lung disease characterized by an arrest of lung development and interference with alveolarization. Antenatal glucocorticoids can induce early lung maturation clinically, but new information from transgenic and other experimental models indicates that traditional explanations for glucocorticoid effects on the developing lung are inadequate. These very preterm infants have lungs with small lung gas volumes and delicate lung tissue that are susceptible to injury with the initiation of ventilation and subsequent ventilation. Antenatal proinflammatory exposures are frequent in very preterm infants, and postnatal injury is associated with elevations of proinflammatory cytokines in the lungs. One hypothesis is that proinflammatory cytokines can promote or interfere with lung development as well as promote lung injury. Mechanisms of lung injury being characterized in the adult lung may have unique characteristics in the developing lung.

Increased risk of fibrosing alveolitis associated with interleukin-1 receptor antagonist and tumor necrosis factor-alpha gene polymorphisms

Fibrosing alveolitis (FA) is characterized by persistent inflammation and elevated production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1beta), and interleukin-1 receptor antagonist (IL-1ra) in the lung. Single base variations at position +2018 in the IL-1ra gene (IL-1RN) and position -308 in the TNF-alpha gene (TNF-A) are overrepresented in other chronic inflammatory disease populations. We have tested the hypothesis that predisposition to FA may also be influenced by these polymorphisms by genotyping 88 cases and matched controls from England and 61 cases and 103 unmatched controls from Italy. The rarer allele for IL-1RN and TNF-A was designated allele 2 in each case. For IL-1RN allele 2, in the English group, the relative odds of FA were increased in homozygous subjects by an odds ratio (OR) of 10.2 (95% confidence intervals [CI], 1.26 to 81.4; p = 0.03) and for carriers by an OR of 1.85 (95% CI, 0.94 to 3.63; p = 0.075). In the Italian population, the risk of FA was increased, in IL-1RN allele 2 homozygotes (OR, 2.54; 95% CI, 0.68 to 9.50; p = 0.2) and in carriers (OR 2.40; 95% CI, 1.26 to 4.60; p = 0.008). Carriage of TNF-A allele 2 was also associated with increased risk of FA in the English (OR, 1.85; 95% CI, 0.94 to 3.63; p = 0.075) and Italian (OR, 2.50; 95% CI, 1.14 to 5.47; p = 0.022) populations. These data suggest IL-1RN (+2018) allele 2 and TNF-A (-308) allele 2 confer increased risk of developing FA and, therefore, that unopposed IL-1beta and/or excessive TNF-alpha may play a pathophysiologic role in this condition.

Interstitial fibrosis and growth factors

Interstitial pulmonary fibrosis (IPF) is scarring of the lung caused by a variety of inhaled agents including mineral particles, organic dusts, and oxidant gases. The disease afflicts millions of individuals worldwide, and there are no effective therapeutic approaches. A major reason for this lack of useful treatments is that few of the molecular mechanisms of disease have been defined sufficiently to design appropriate targets for therapy. Our laboratory has focused on the molecular mechanisms through which three selected peptide growth factors could play a role in the development of IPF. Hundreds of growth factors and cytokines could be involved in the complex disease process. We are studying platelet-derived growth factor because it is the most potent mesenchymal cell mitogen yet described, transforming growth factor beta because it is a powerful inducer of extracellular matrix (scar tissue) components by mesenchymal cells, and tumor necrosis factor alpha because it is a pleiotropic cytokine that we and others have shown is essential for the development of IPF in animal models. This review describes some of the evidence from studies in humans, in animal models, and in vitro, that supports the growth factor hypothesis. The use of modern molecular and transgenic technologies could elucidate those targets that will allow effective therapeutic approaches.

Modulation of lung local immune responses by oral administration of a herbal medicine Sho-saiko-to

Sho-saiko-to (SST), a Chinese/Japanese herbal medicine (Kampo medicine) widely used to treat chronic hepatitis in Japan, is known to modulate immune responses, and thus its immunomodulating activity may be responsible for its bi-directional effects on the lungs as therapeutic efficacy in various lung diseases and involvement in development of interstitial pneumonia. We administered SST to BALB/c mice orally and examined the lung tissue levels of pro/anti-inflammatory cytokines, interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), and the effects of SST on acute lung injury induced by instillation of lipopolysaccharide (LPS) or IL-1. Although SST had no effect on lung TNF-alpha or IL-1beta level, it increased IL-6. Investigation of active fractions of SST suggested that multiple ingredients were supposed to be responsible for IL-6-inducing activity. Liquiritigenin, a metabolite of liquiritin which is one of the major ingredients in SST enhanced in vitro IL-6 production in anti-CD3 monoclonal antibody (anti-CD3 mAb)-stimulated lung mononuclear cells in a cell-type specific and dose-dependent manner. SST suppressed LPS-induced lung injury at the later phase when lung leak was evident while being ineffective on initial neutrophil sequestration to the lung in these models. These findings suggest that SST modulates lung inflammation by regulating local immune response.

Introduction of the interleukin-10 gene into mice inhibited bleomycin-induced lung injury in vivo

Interleukin (IL)-10 has been shown to reduce many inflammatory reactions. We investigated the in vivo effects of IL-10 on a bleomycin-induced lung injury model. Hemagglutinating virus of Japan (HVJ)-liposomes containing a human IL-10 expression vector (hIL10-HVJ) or a balanced salt solution as a control (Cont-HVJ) was intraperitoneally injected into mice on day -3. This was followed by intratracheal instillation of bleomycin (0.8 mg/kg) on day 0. Myeloperoxidase activity of bronchoalveolar lavage fluid and tumor necrosis factor-alpha mRNA expression in bronchoalveolar lavage fluid cells on day 7 and hydroxyproline content of the whole lung on day 21 were inhibited significantly by hIL10-HVJ treatment. However, Cont-HVJ treatment could not suppress any of these parameters. We also examined the in vitro effects of IL-10 on the human lung fibroblast cell line WI-38. IL-10 significantly reduced constitutive and transforming growth factor-beta-stimulated type I collagen mRNA expression. However, IL-10 did not affect the proliferation of WI-38 cells induced by platelet-derived growth factor. These data suggested that exogenous IL-10 may be useful in the treatment of pulmonary fibrosis.

Adenoviral E3-14.7K protein in LPS-induced lung inflammation

The adenoviral E3-14.7K protein is a cytoplasmic protein synthesized after adenoviral infection. To assess the contribution of E3-14. 7K-sensitive pathways in the modulation of inflammation by the respiratory epithelium, inflammatory responses to intratracheal lipopolysaccharide (LPS) and tumor necrosis factor (TNF)-alpha were assessed in transgenic mice bearing the adenoviral E3-14.7K gene under the direction of the surfactant protein (SP) C promoter. When E3-14.7K transgenic mice were administered LPS intratracheally, lung inflammation as indicated by macrophage and neutrophil accumulation in bronchoalveolar lavage fluid was decreased compared with wild-type control mice. Lung inflammation and epithelial cell injury were decreased in E3-14.7K mice 24 and 48 h after LPS administration. Intracellular staining for surfactant proprotein (proSP) B, proSP-C, and SP-B was decreased and extracellular staining was markedly increased in wild-type mice after LPS administration, consistent with LPS-induced lung injury. In contrast, intense intracellular staining of proSP-B, proSP-C, and SP-B persisted in type II cells of E3-14.7K mice, whereas extracellular staining of proSP-B and proSP-C was absent. Inhibitory effects of intratracheal LPS on SP-C mRNA were ameliorated by expression of the E3-14.7K gene. Similar to the response to LPS, lung inflammation after intratracheal administration of TNF-alpha was decreased in E3-14.7K transgenic mice. Levels of TNF-alpha after LPS administration were similar in wild-type and E3-14.7K-bearing mice. Cell-selective expression of E3-14.7K in the respiratory epithelium inhibited LPS- and TNF-alpha-mediated lung inflammation, demonstrating the critical role of respiratory epithelial cells in LPS- and TNF-alpha-induced lung inflammation.

Changes in pulmonary histology and exfoliated bronchoalveolar cells induced by in vivo introduction of the tumor necrosis factor-alpha gene

An inflammatory cytokine, tumor necrosis factor (TNF)-alpha, has been implicated in the pathogenesis of inflammatory lung diseases such as interstitial pneumonia (IP). To clarify the role of the inflammatory cytokine in the pathogenesis of lung inflammation, we introduced a murine TNF-alpha gene into murine lungs by the hemagglutinating virus of Japan (HVJ)-liposome method. Seven days after the TNF-alpha gene introduction resulted in marked cellular infiltration of alveoli, and mild histological change was observed 28 days after the gene introduction. Electron microscopic analysis revealed minimal deposition of collagen fibrils. Analysis of the BAL revealed that the total cell number was markedly increased 3 and 7 days after the gene introduction, and more than 90% of the cells were macrophages. The increase in the cell number was returned to below the normal level 28 days after the gene introduction. During the development of IP, TNF-alpha may regulate pathologic change of the pulmonary interstitium and alveolar cells.

Secondary alveolar echinococcosis in lymphotoxin-alpha and tumour necrosis factor-alpha deficient mice: exacerbation of Echinococcus multilocularis larval growth is associated with cellular changes in the periparasitic granuloma

The availability of mice carrying a deletion of LT-alpha and tumour necrosis factor (TNF)-alpha genes enabled us to investigate the role of the TNF during alveolar echinococcosis. We compared the growth rate of Echinococcus multilocularis in LT-alphaTNF-alpha +/+ mice to that of mice having either no or only one LT-alphaTNF-alpha functionnal allele. LT-alphaTNF-alpha -/- mice harboured a significantly higher parasite burden than did the other two populations at 5, 10, and 15 weeks of infection, and they did not survive thereafter. Liver metacestodes removed from these mice were alive and the dehydrogenase activities of peritoneal metacestodes were decreased. Liver lesions regressed in most wild-type mice. Indeed, dead parasites were cordoned by granulomas containing numerous macrophages and lymphocytes leading to focal liver fibrosis at an early stage of infection. In contrast, most of LT-alphaTNF-alpha -/- mice harboured metacestodes interspersed with leucocytes, realising purulent abscesses with secondary extensive irregular fibrosis at a late stage of infection. Heterozygous mice had behavioural characteristics intermediate between homozygous mutants and wild-type mice. Levels of E. multilocularis-specific delayed-type hypersensitivity and serum antibodies were slightly decreased in LT-alphaTNF-alpha -/- mice. This study shows that TNF-alpha and/or LT-alpha genes play an essential role in the immune protection mechanisms against E. multilocularis at the site of infection.

Idiopathic pneumonia after bone marrow transplantation: cytokine activation and lipopolysaccharide amplification in the bronchoalveolar compartment

OBJECTIVE

To determine whether idiopathic pneumonia syndrome (IPS), a form of noninfectious lung injury that follows bone marrow transplantation, is associated with cytokine activation and increased susceptibility to lipopolysaccharide (LPS).

DESIGN

Case series.

SETTING

Tertiary referral center for marrow transplantation.

PATIENTS

Recipients with biopsy-confirmed IPS; normal volunteers and marrow transplant recipients without IPS were analyzed as controls.

MEASUREMENTS AND MAIN RESULTS

Levels of lymphocyte and macrophage-derived cytokines as well as components of the LPS, LPS-binding protein (LBP), and CD14 system in bronchoalveolar lavage (BAL) fluid were determined. We found evidence of increased vascular permeability (BAL protein) and inflammatory cytokine activation (interleukin-1, interleukin-2, interleukin-6, and tumor necrosis factor-alpha) in patients with IPS. Patients without IPS had BAL fluid cytokine and protein levels that were similar to levels in BAL fluid from normal volunteers. Moreover, components of the LPS amplification system (LBP and soluble CD14) were increased in patients with IPS but not in patients without IPS.

CONCLUSIONS

These results provide direct evidence for proinflammatory cytokine activation in IPS and suggest that these patients might be at increased risk for LPS-mediated injury through the LBP amplification pathway.

Cellular and molecular mechanisms of asbestos-induced fibrosis

Pleural and pulmonary fibrosis (asbestosis) are ramifications of occupational exposures to asbestos fibers, a diverse family of ubiquitous, naturally-occurring minerals. The pathogenesis of asbestos-associated fibrosis involves the participation of a number of cell types and is characterized by an early and persistent inflammatory response that involves the generation of oxidants, growth factors, chemokines, and cytokines. These mediators may also contribute directly to cell injury, proliferation, and fibrogenesis. After interaction with cells, asbestos fibers trigger a number of signaling cascades involving mitogen-activated protein kinases (MAPK) and nuclear factor kappa-B (NF-kappaB). Activation of transcription factors such as NF-kappaB and activator protein-1 (AP-1) may be linked to increases in early response genes (e.g., c-jun and c-fos) which govern proliferation, apoptosis, and inflammatory changes in the cells of the lung. The goal of this article is to review the cellular and molecular mechanisms of asbestos-induced fibrosis that may be critical to the development of effective treatment regimens.

Soluble tumor necrosis factor (TNF) receptors p55 and p75 and interleukin-10 downregulate TNF-alpha activity during the lung response to silica particles in NMRI mice

We have found reduced activity of tumor necrosis factor (TNF)-alpha accompanying resolving and fibrosing alveolitis induced in NMRI mice by mineral particles (MnO2 and SiO2, respectively), which is in apparent contradiction to the well-recognized proinflammatory and profibrotic activities of this cytokine. The objective of this study was to examine the mechanisms involved in this paradoxical response in NMRI mice. Although lung tissue messenger RNA (mRNA) levels for TNF-alpha were transiently (up to 15 d) and persistently (up to 120 d) upregulated in the resolving and fibrosing models, respectively, these changes were not accompanied by a parallel release of TNF-alpha protein, which was respectively transiently and persistently downregulated in bronchoalveolar lavage fluid and bronchoalveolar lavage cell cultures. The downregulation of the TNF-alpha protein was concurrent with the accumulation of recruited polymorphonuclear neutrophils (PMNs) in alveoli, and coculture experiments showed that PMN explanted from the lungs of mice treated with silica particles were able to downregulate the expression of TNF-alpha protein by naive alveolar macrophages. In addition, PMN depletion prevented the downregulation of TNF-alpha induced by silica, further establishing the role of PMNs in the downregulation of TNF-alpha. The possible degradation of TNF-alpha by proteolytic enzymes could be excluded. Marked increases in soluble p55 and p75 TNF receptors (sTNF-R), as well as in interleukin (IL)-10, paralleled the downregulation of TNF-alpha protein. The role of these mediators in the observed reduction of TNF-alpha activity was confirmed by immunoneutralizing the activity of p55 and p75 sTNF-R and by using IL-10-deficient animals. Because IL-10 also exerts profibrotic activity in addition to its antiinflammatory activity, the protracted overproduction of IL-10 observed in fibrosing alveolitis may help the understanding of why, in NMRI mice treated with silica particles, lung fibrosis develops in association with a downregulation of TNF-alpha.

On the role of tumor necrosis factor and receptors in models of multiorgan failure, rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease

The specific role of the tumor necrosis factor (TNF)/TNF receptor (TNFR) system in disease pathogenesis still remains an unresolved puzzle. Recent studies in transgenic and knockout animals, where the pathogenic influence of genetically perturbed TNF expression has been evaluated, indicate that several pathways of TNF/TNFR action may contribute independently or in concert to initiate, promote or downregulate disease pathogenesis. Evidently, organ-specific inflammatory or autoimmune pathology may ensue due to sustained activation by TNF of innate immune cells and inflammatory responses, which may consequently lead to tissue damage and to organ-specific chronic pathology. However, more cryptic functions of this molecule may be considered to play a significant part in the development of TNF-mediated pathologies. Direct interference of TNF with the differentiation, proliferation or death of specific pathogenic cell targets may be an alternative mechanism for disease initiation or progression. In addition to these activities, there is now considerable evidence to suggest that TNF may also directly promote or downregulate the adaptive immune response. It is therefore evident that no general scenario may adequately describe the role of TNF in disease pathogenesis. In this article, we aim to place these diverse functions of TNF/TNFRs into context with the development of specific pathology in murine models of multiorgan failure, rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease.

A novel pathway for tumor necrosis factor-alpha and ceramide signaling involving sequential activation of tyrosine kinase, p21(ras), and phosphatidylinositol 3-kinase

Treatment of confluent rat2 fibroblasts with C2-ceramide (N-acetylsphingosine), sphingomyelinase, or tumor necrosis factor-alpha (TNFalpha) increased phosphatidylinositol (PI) 3-kinase activity by 3-6-fold after 10 min. This effect of C2-ceramide depended on tyrosine kinase activity and an increase in Ras-GTP levels. Increased PI 3-kinase activity was also accompanied by its translocation to the membrane fraction, increases in tyrosine phosphorylation of the p85 subunit, and physical association with Ras. Activation of PI 3-kinase by TNFalpha, sphingomyelinase, and C2-ceramide was inhibited by tyrosine kinase inhibitors (genistein and PP1). The stimulation of PI 3-kinase by sphingomyelinase and C2-ceramide was not observed in fibroblasts expressing dominant-negative Ras (N17) and the stimulation by TNFalpha was decreased by 70%. PI 3-kinase activation by C2-ceramide was not modified by inhibitors of acidic and neutral ceramidases, and it was not observed with the relatively inactive analog, dihydro-C2-ceramide. It is proposed that activation of Ras and PI 3-kinase by ceramide can contribute to signaling effects of TNFalpha that occur downstream of sphingomyelinase activation and result in increased fibroblasts proliferation.

Reduced tumor necrosis factor-alpha and transforming growth factor-beta1 expression in the lungs of inbred mice that fail to develop fibroproliferative lesions consequent to asbestos exposure

Tumor necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta mRNA and protein expression and the degree of fibroproliferative response to inhaled asbestos fibers are clearly reduced in the 129 inbred mouse strain as compared with typical fibrogenesis observed in the C57BL/6 inbred strain. The C57BL/6 mice showed prominent lesions at bronchiolar-alveolar duct (BAD) junctions where asbestos fibers deposit and responding macrophages accumulate. The 129 mice, however, were generally indistinguishable from controls even though the numbers of asbestos fibers deposited in the lungs of all exposed animals were the same. Quantitative morphometry of H&E-stained lung sections comparing the C57BL/6 and 129 mice showed significantly less mean cross-sectional area of the BAD junctions in the 129 animals, apparent at both 48 hours and 4 weeks after exposure. In addition, fewer macrophages had accumulated at these sites in the 129 mice. Nuclear bromodeoxyuridine immunostaining demonstrated that the number of proliferating cells at first alveolar duct bifurcations and in adjacent terminal bronchioles was significantly reduced in the 129 strain compared with C57BL/6 mice at 48 hours after exposure (P < 0.01). TNF-alpha and TGF-beta1 gene expression, as measured by in situ hybridization, was reduced in the 129 mice at 48 hours after exposure, and expression of TNF-alpha and TGF-beta1 protein, as measured by immunohistochemistry, was similarly reduced or absent in the 129 animals. We postulate that the protection afforded the 129 mice is related to reduction of growth factor expression by the bronchiolar-alveolar epithelium and lung macrophages.

Intratracheal injection of adenovirus containing the human MnSOD transgene protects athymic nude mice from irradiation-induced organizing alveolitis

PURPOSE

A dose and volume limiting factor in radiation treatment of thoracic cancer is the development of fibrosis in normal lung. The goal of the present study was to determine whether expression prior to irradiation of a transgene for human manganese superoxide dismutase (MnSOD) or human copper/zinc superoxide dismutase (Cu/ZnSOD) protects against irradiation-induced lung damage in mice.

METHODS AND MATERIALS

Athymic Nude (Nu/J) mice were intratracheally injected with 10(9) plaque-forming units (PFU) of a replication-incompetent mutant adenovirus construct containing the gene for either human MnSOD, human copper/zinc superoxide dismutase (Cu/ZnSOD) or LacZ. Four days later the mice were irradiated to the pulmonary cavity to doses of 850, 900, or 950 cGy. To demonstrate adenoviral infection, nested reverse transcriptase-polymerase chain reaction (RT-PCR) was carried out with primers specific for either human MnSOD or Cu/ZnSOD transgene on freshly explanted lung, trachea, or alveolar type II cells, and immunohistochemistry was used to measure LacZ expression. RNA was extracted on day 0, 1, 4, or 7 after 850 cGy of irradiation from lungs of mice that had previously received adenovirus or had no treatment. Slot blot analysis was performed to quantitate RNA expression for IL-1, tumor necrosis factor (TNF)-alpha, TGF-beta, MnSOD, or Cu/ZnSOD. Lung tissue was explanted and tested for biochemical activity of MnSOD or Cu/ZnSOD after adenovirus injection. Other mice were sacrificed 132 days after irradiation, lungs excised, frozen in OCT, (polyvinyl alcohol, polyethylene glycol mixture) sectioned, H&E stained, and evaluated for percent of the lung demonstrating organizing alveolitis.

RESULTS

Mice injected intratracheally with adenovirus containing the gene for human MnSOD had significantly reduced chronic lung irradiation damage following 950 cGy, compared to control mice or mice injected with adenovirus containing the gene for human Cu/ZnSOD or LacZ. Immunohistochemistry for LacZ protein in adenovirus LacZ (Ad-LacZ)-injected mice demonstrated expression of LacZ in both the upper and lower airway. Nested RT-PCR showed lung expression of MnSOD and Cu/ZnSOD for at least 11 days following infection with each respective adenovirus construct. Nested RT-PCR using primers specific for human MnSOD demonstrated increased expression of the human MnSOD transgene in the trachea and alveolar type II cells 4 days after virus injection on the day of irradiation. At this time point, increased biochemical activity of MnSOD and Cu/ZnSOD respectively, was detected in lungs from these two adenovirus groups, compared to each other or to control or adenovirus LacZ mice. Slot blot analysis of RNA from lungs of mice in each group following 850 cGy irradiation demonstrated decreased expression of mRNA for interleukin-I (IL-1), TNF-alpha, and transforming growth factor-beta (TGF-beta) in the MnSOD adenovirus-injected mice, compared to irradiated control, LacZ, or Cu/ZnSOD adenovirus-injected, irradiated mice. Mice receiving adenovirus MnSOD showed decreased organizing alveolitis at 132 days in all three dose groups, compared to irradiated control or Ad-LacZ, or Ad-Cu/ZnSOD mice.

CONCLUSIONS

Overexpression of MnSOD in the lungs of mice prior to irradiation prevents irradiation-induced acute and chronic damage quantitated as decreased levels of mRNA for IL-1, TNF-alpha, and TGF-beta in the days immediately following irradiation, and decrease in the percent of lung demonstrating fibrosis or organizing alveolitis at 132 days. These data provide a rational basis for development of gene therapy as a method of protection of the normal lung from acute and chronic sequelae of ionizing irradiation.

The involvement of Fas-Fas ligand pathway in fibrosing lung diseases

Pulmonary fibrosis begins with alveolitis, which progresses to destruction of lung tissue and excess collagen deposition. This process could be the result of DNA damage and a form of apoptosis. Therefore, we hypothesized that Fas ligand (FasL), which induces apoptosis in cells expressing Fas antigen (Fas), is associated with pulmonary fibrosis. We examined frozen lung tissues from seven patients with idiopathic pulmonary fibrosis (IPF), and bronchoalveolar lavage fluid (BALF) cells from 19 patients with IPF and from 17 patients with interstitial pneumonia associated with collagen vascular diseases (CVD-IP). We used five frozen lungs with normal lung parenchyma and BALF cells from 10 patients with solitary pulmonary nodule as controls. Reverse transcription-polymerase chain reaction (RT-PCR) showed that FasL messenger RNA (mRNA) was expressed in BALF cells from all patients with IPF and from 15 of 16 patients with CVD-IP. FasL mRNA was not detected in BALF cells except in one of 10 controls. RT in situ PCR detected FasL mRNA in inflammatory cells in BALF from patients with IPF. Immunohistochemistry detected FasL protein in infiltrating lymphocytes and granulocytes in all of seven frozen lung tissues of IPF, but in none of five control lung tissues. Additionally, the expression of Fas appeared to be upregulated in bronchiolar and alveolar epithelial cells in IPF compared with normal lung parenchyma by immunohistochemistry. We conclude that Fas and FasL were upregulated in fibrosing lung diseases and may associate with DNA damage or apoptosis of bronchiolar and alveolar epithelial cells in this disorder.

TNF-alpha receptor knockout mice are protected from the fibroproliferative effects of inhaled asbestos fibers

We have demonstrated that C57BL/6-129 hybrid mice with genes for both the 55kd and 75kd receptors for TNF-alpha knocked out (TNF-alphaRKO) fail to develop fibroproliferative lesions after asbestos exposure. There is good evidence that TNF-alpha plays a major role in mediating interstitial pulmonary fibrosis. Our findings support this view and we present here new data obtained by in situ hybridization showing that expression of the genes coding for transforming growth factor alpha (TGF-alpha) and platelet-derived growth factor A-chain (PDGF-A) is reduced in the TNF-alphaRKO mice compared with control animals. In accordance with this observation, data on bromodeoxyuridine (BrdU) incorporation in the lungs of the TNF-alphaRKO mice show no increases over unexposed control animals. In contrast, wild-type control mice exposed to asbestos exhibit 15- to 20-fold increases in BrdU uptake and consequently develop fibrogenic lesions. Even though the levels of TNF-alpha gene expression and protein production were increased in the asbestos-exposed TNF-alphaRKO mice, the lack of receptor signaling protected the mice from developing fibroproliferative lesions. We agree with the view that TNF-alpha is essential for the development of interstitial pulmonary fibrosis and postulate that TNF-alpha mediates its effects through activation of other growth factors such as PDGF and TGF-alpha that control cell growth and matrix production.

Evidence of phenotypic alteration as a cause of systolic dysfunction in the failing heart

This article describes the phenotype of dilated cardiomyopathy in humans and describes parallel studies in experimental models that support or refute the relevance of these changes to the development of the heart failure phenotype.

Morphometric analysis of insulin-like growth factor-I localization in lung tissues of patients with idiopathic pulmonary fibrosis

Insulin-like growth factor-I (IGF-I) has been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF) through its ability to stimulate fibroblast proliferation and collagen synthesis. However, although alveolar macrophages (AM) have been shown to express this growth factor, it is likely to also have other cellular sources. We sought to determine the distribution of cells expressing IGF-I in lung tissues obtained from 10 patients with IPF and 10 control subjects. We evaluated the levels of IGF-I and of a macrophage/monocyte-specific marker, CD68, by immunocytochemistry and quantified by morphometry. In control subjects, IGF-I was localized principally to AM. In contrast, in IPF patients IGF-I was localized to AM, interstitial macrophages, alveolar epithelial cells, and ciliated columnar epithelial cells. The normalized volume density (Vv) of IGF-I-positive (IGF-I+) interstitial macrophages (Vv of IGF-I+ interstitial macrophages/Vv of lung x 100) was increased in patients with IPF as compared with control subjects, and the ratio of Vv of IGF-I+ to CD68(+) interstitial macrophages correlated with: (1) the degree of clinical impairment in patients with IPF as measured by their clinical-radiologic-physiologic (CRP) score; and (2) the degree of collagen deposition in the interstitium. These findings support a role for interstitial macrophages as a source of IGF-I in IPF.

Cytokine Interaction and Immune Responses during Schistosoma mansoni Infection

Of the estimated 200 million people infected with Schistosoma, a subset develop severe life-threatening disease. Adult Schistosoma mansoni are refractory to the immune response and are long-lived, causing chronic exposure to parasite antigen. Although the adult worms themselves are not antigenically inert, it is the parasite eggs that, by accumulating in the liver and traversing the intestinal wall, place a complex series of often-conflicting demands on the host's immune system. In this article, Laura Rosa Brunet, David Dunne and Edward Pearce discuss data from experimental studies in the mouse and field studies in endemic areas that combine to suggest that it is a failure to juggle this immunological conflict that results in severe disease.

Late-onset chronic inflammatory encephalopathy in immune-competent and severe combined immune-deficient (SCID) mice with astrocyte-targeted expression of tumor necrosis factor

To examine the role of tumor necrosis factor (TNF)-alpha in the pathogenesis of degenerative disorders of the central nervous system (CNS), transgenic mice were developed in which expression of murine TNF-alpha was targeted to astrocytes using a glial fibrillary acidic protein (GFAP)-TNF-alpha fusion gene. In two independent GFAP-TNFalpha transgenic lines (termed GT-8 or GT-2) adult (>4 months of age) animals developed a progressive ataxia (GT-8) or total paralysis affecting the lower body (GT-2). Symptomatic mice had prominent meningoencephalitis (GT-8) or encephalomyelitis (GT-2) in which large numbers of B cells and CD4+ and CD8+ T cells accumulated at predominantly perivascular sites. The majority of these lymphocytes displayed a memory cell phenotype (CD44high, CD62Llow, CD25-) and expressed an early activation marker (CD69). Parenchymal lesions contained mostly CD45+ high, MHC class II+, and Mac-1+ cells of the macrophage microglial lineage with lower numbers of neutrophils and few CD4+ and CD8+ T cells. Cerebral expression of the cellular adhesion molecules ICAM-1, VCAM-1, and MAdCAM as well as a number of alpha- and beta-chemokines was induced or upregulated and preceded the development of inflammation, suggesting an important signaling role for these molecules in the CNS leukocyte migration. Degenerative changes in the CNS of the GFAP-TNFalpha mice paralleled the development of the inflammatory lesions and included primary and secondary demyelination and neurodegeneration. Disease exacerbation with more extensive inflammatory lesions that contained activated cells of the macrophage/microglial lineage occurred in GFAP-TNFalpha mice with severe combined immune deficiency. Thus, persistent astrocyte expression of murine TNF-alpha in the CNS induces a late-onset chronic inflammatory encephalopathy in which macrophage/microglial cells but not lymphocytes play a central role in mediating injury.

Transfer of tumor necrosis factor-alpha to rat lung induces severe pulmonary inflammation and patchy interstitial fibrogenesis with induction of transforming growth factor-beta1 and myofibroblasts

Tumor necrosis factor-alpha is up-regulated in a variety of different human immune-inflammatory and fibrotic pulmonary pathologies. However, its precise role in these pathologies and, in particular, the mechanism(s) by which it may induce fibrogenesis are not yet elucidated. Using a replication-deficient adenovirus to transfer the cDNA of tumor necrosis factor-alpha to rat lung, we have been able to study the effect of transient but prolonged (7 to 10 days) overexpression of tumor necrosis factor-alpha in normal adult pulmonary tissue. We have demonstrated that local overexpression resulted in severe pulmonary inflammation with significant increases in neutrophils, macrophages, and lymphocytes and, to a lesser extent, eosinophils, with a peak at day 7. By day 14, the inflammatory cell accumulation had declined, and fibrogenesis became evident, with fibroblast accumulation and deposition of extracellular matrix proteins. Fibrotic changes were patchy but persisted to beyond day 64. To elucidate the mechanism underlying this fibrogenesis, we examined bronchoalveolar fluids for the presence of the fibrogenic cytokine transforming growth factor-beta1 and tissues for induction of alpha-smooth muscle actin-rich myofibroblasts. Transforming growth factor-beta1 was transiently elevated from day 7 (peak at day 14) immediately preceding the onset of fibrogenesis. Furthermore, there was a striking accumulation of myofibroblasts from day 7, with the most extensive and intense immunostaining at day 14, ie, coincident with the up-regulation of transforming growth factor-beta1 and onset of fibrogenesis. Thus, we have provided a model of tumor necrosis factor-alpha-mediated pulmonary inflammation and fibrosis in normal adult lung, and we suggest that the fibrogenesis may be mediated by the secondary up-regulation of transforming growth factor-beta1 and induction of pulmonary myofibroblasts.

Role of TNFR1 and TNFR2 in TNF-Induced Platelet Consumption in Mice

An injection of TNF in mice induced profound thrombocytopenia, due to an increase of platelet consumption, that was evident after 1 h and lasted for 3 days. This process was evident in mice that were genetically deficient in TNFR2 (p75) but not in mice lacking TNFR1 (p55), indicating that the process is mediated by TNFR1-bearing cells. To explore the site of action of TNF, labeled platelets from TNFR1 −/− or +/+ donors were transferred to TNFR1 −/− or +/+ recipients. TNF induced the consumption of platelets from TNFR1 −/− donors when injected into +/+ recipients, while platelets from +/+ donors were not consumed when present in TNFR1 −/− recipients; this finding indicates that TNF acts on the TNFR1 of host cells but does not act on platelets. The expression of TNFRs is consistent with this interpretation, since TNFRs were not detected on platelets by flow cytometry. In megakaryocytes, the expression of TNFR1 was detected by immunohistochemistry. These results indicate that TNF induces platelet consumption by acting not on platelets directly but on the TNFR1 of other cells, presumably increasing the release of factors with agonist activity for platelets.

TNF-alpha inhibits liver collagen-alpha 1(I) gene expression through a tissue-specific regulatory region

Although tumor necrosis factor-alpha (TNF-alpha) inhibits collagen-alpha 1(I) gene expression in cultured hepatic stellate cells, assessment of its effects on hepatic collagen expression is complicated by the confounding variables of tissue necrosis and inflammation. Therefore, we analyzed whether chronically elevated serum TNF-alpha affects constitutive hepatic collagen metabolism in vivo by inoculating nude mice with Chinese hamster ovary (CHO) cells secreting TNF-alpha (TNF-alpha mice) or with control CHO cells (control mice). Before the onset of weight loss, collagen synthesis and collagen gene expression were inhibited in the liver of TNF-alpha mice. In transgenic mice, after 8 h, TNF-alpha (500 ng at 0 and 5 h) inhibited the liver expression of the collagen-alpha 1(I)-human growth hormone (hGH) transgene containing the first intron and -440 bp of the 5' region. Similarly, in cultured hepatic stellate cells isolated from these transgenic animals, the -440 bp collagen-alpha 1(I)-hGH transgene was responsive to TNF-alpha treatment independent of the activation of these cells. Transfection studies in stellate cells allowed further characterization of this TNF-alpha-responsive segment to -220 bp of the 5' region. Because in the skin the inhibitory effect of TNF-alpha involves a regulatory region of the collagen-alpha 1(I) gene beyond -440 bp, we herein identify a novel tissue-specific regulation of collagen-alpha 1(I) gene by TNF-alpha.

Tumor necrosis factor alpha gene regulation: enhancement of C/EBPbeta-induced activation by c-Jun

Tumor necrosis factor alpha (TNF alpha) is a key regulatory cytokine whose expression is controlled by a complex set of stimuli in a variety of cell types. Previously, we found that the monocyte/macrophage-enriched nuclear transcription factor C/EBPbeta played an important role in the regulation of the TNF alpha gene in myelomonocytic cells. Abundant evidence suggests that other transcription factors participate as well. Here we have analyzed interactions between C/EBPbeta and c-Jun, a component of the ubiquitously expressed AP-1 complex. In phorbol myristate acetate (PMA)-treated Jurkat T cells, which did not possess endogenous C/EBPbeta, expression of c-Jun by itself had relatively little effect on TNF alpha promoter activity. However, the combination of C/EBPbeta and c-Jun was synergistic, resulting in greater than 130-fold activation. This effect required both the leucine zipper and DNA binding domains, but not the transactivation domain, of c-Jun, plus the AP-1 binding site centered 102/103 bp upstream of the transcription start site in the TNF alpha promoter. To determine if C/EBPbeta and c-Jun might cooperate to regulate the cellular TNF alpha gene in myelomonocytic cells, U937 cells that possess endogenous C/EBPbeta and were stably transfected with either wild-type c-Jun or the transactivation domain deletion mutant (TAM-67) were examined. U937 cells expressing ectopic wild-type c-Jun or TAM-67 secreted over threefold more TNF alpha than the control line in response to PMA plus lipopolysaccharide. Transient transfection of the U937 cells expressing TAM-67 suggested that TAM-67 binding to the -106/-99-bp AP-1 binding site cooperated with endogenous C/EBPbeta in the activation of the -120 TNF alpha promoter-reporter. DNA binding assays using oligonucleotides derived from the TNF alpha promoter suggested that C/EBPbeta and c-Jun interact in vitro and that the interaction may be DNA dependent. Our data demonstrate that the TNF alpha gene is regulated by the interaction of the ubiquitous AP-1 complex protein c-Jun and the monocyte/macrophage-enriched transcription factor C/EBPbeta and that this interaction contributes to the expression of the cellular TNF alpha gene in myelomonocytic cells. This interaction was unique in that it did not require the c-Jun transactivation domain, providing new insight into the cell-type-specific regulation of the TNF alpha gene.

High Levels of TNF, Soluble TNF Receptors, Soluble ICAM-1, and IFN-γ, but Low Levels of IL-5, Are Associated with Hepatosplenic Disease in Human Schistosomiasis Mansoni

In a case-control study based in two areas of Kenya, hepatosplenic schistosomiasis mansoni was shown to be linked with low levels of IL-5 and with correspondingly high IFN-γ, TNF, and circulating soluble TNF receptor I (sTNFR-I), sTNFR-II, and sICAM-1. PBMC from the hepatosplenic cases responded to in vitro Ag stimulation with significantly higher levels of IFN-γ and TNF, but lower levels of IL-5, compared with nonhepatosplenic controls matched for age and infection intensity. Most of these correlations were confounded by differences between geographical areas. However, principle component analysis identified a high IFN-γ and TNF, and low IL-5 axis in the data as the first principle component; this was significantly associated with hepatosplenomegaly (p &lt; 0.0005) even after controlling for area. High plasma levels of sTNFR-I (p &lt; 0.001), sTNFR-II, (p &lt; 0.0001), and sICAM-1 (p &lt; 0.009) were also significantly associated with hepatosplenomegaly, independently of area, in the case of the soluble forms of both TNF receptors. These parameters were negatively related to IL-5. These results suggest that proinflammatory cytokines are involved in the hepatosplenic disease process in infected individuals who have low anti-inflammatory Th2 responses and that sTNFR may be a useful circulating marker for this disease process, perhaps reflecting the level of TNF activity in hepatic tissues.

Increased tumor necrosis factor-alpha (TNF-alpha) gene expression in parainfluenza type 1 (Sendai) virus-induced bronchiolar fibrosis

Increased airway resistance and airway hyperresponsiveness induced in rats by infection with parainfluenza type I (Sendai) virus is associated with bronchiolar fibrosis. To determine whether increased tumor necrosis factor (TNF)-alpha gene expression is an important regulatory event in virus-induced bronchiolar fibrosis, pulmonary TNF-alpha mRNA and protein expression was assessed in rat strains that are susceptible (Brown Norway; BN) and resistant (Fischer 344; F344) to virus-induced bronchiolar fibrosis. Virus-inoculated BN rats had increased TNF-alpha pulmonary mRNA levels (P < 0.05) and increased numbers of bronchiolar macrophages and fibroblasts expressing TNF-alpha protein compared with virus-inoculated F344 rats (P < 0.05). Virus inoculation also induced elevated TNF-alpha mRNA and protein levels (P < 0.05) in cultured rat alveolar macrophages (NR8383 cells). A 55-kd soluble TNF receptor-immunoglobulin G fusion protein (sTNFR-IgG) was used to inhibit TNF-alpha bioactivity in virus-inoculated BN rats. Treated rats had fewer proliferating bronchiolar fibroblasts, as detected by bromodeoxyuridine incorporation, compared with virus-inoculated control rats (P < 0.05). There was also increased mortality in p55sTNFR-IgG-treated virus-inoculated rats associated with increased viral replication and decreased numbers of macrophages and lymphocytes in bronchoalveolar lavage fluid (P < 0.05). The results of this study indicate that 1) Sendai virus can directly up-regulate TNF-alpha mRNA and protein expression in macrophages, 2) TNF-alpha is an important mediator of virus-induced bronchiolar fibrosis, and 3) TNF-alpha has a critical role in the termination of Sendai viral replication in the lung.

Idiopathic pneumonia syndrome in mice after allogeneic bone marrow transplantation

Pulmonary complications are a major clinical problem following allogeneic bone marrow transplantation (BMT), contributing to more than 30% of transplant-related mortalities. Idiopathic pneumonia syndrome is responsible for significant mortality among BMT patients. However, the etiology of injury to the lung parenchyma by this disease syndrome is unknown and it has been difficult to evaluate the cellular and molecular mechanisms underlying IPS in the absence of a suitable animal model. To study post-BMT lung disease during graft-versus-host disease (GVHD), we have developed a murine model that utilizes a semi-allogeneic parental --> F1 transplant strategy to induce a mild form of GVHD. Progressive inflammatory lung disease developed in animals with mild GVHD, as indicated by changes in immune cell distribution and cytokine expression in the lungs of transplanted animals. Histologic analysis of lung tissue from GVHD mice at 3 wk post-BMT showed minor immunopathologic changes compared with control mice. In contrast, lungs of GVHD mice at 12 wk displayed histopathologic hallmarks of interstitial pneumonitis, such as prominent perilumenal mononuclear cell infiltration and areas of alveolar congestion. Flow cytometric analysis of lung interstitial cells of GVHD mice revealed an increase in CD8+ T-cells at week 3, which decreased to normal levels by week 12 post-BMT. Simultaneously, the percentage of CD4+ T-cells increased progressively above normal levels and peaked at week 7 post-BMT. Analysis of cytokine mRNA expression in lung tissue indicated that steady state levels of interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, interferon-gamma, and IL-12 were significantly elevated in lungs of GVHD mice at 3 wk post-BMT compared with untreated controls. Mice that were transplanted with allogeneic bone marrow alone (BMT controls) also displayed elevated expression of these cytokines, although only IL-6 was significantly higher than in untreated controls. In contrast, at 12 wk after transplantation only TNF-alpha and IL-12 levels remained elevated in GVHD mice, suggesting prolonged macrophage activation. On the basis of these findings, we conclude that allogeneic bone marrow transplantation in this mouse model causes a progressive interstitial pneumonitis, which is characterized by an acute influx of CD8+ T-cells, followed in the chronic phase by a prominent accumulation of CD4+ T-cells, and is associated with persistent production of cytokines known to activate macrophages.

Immunophenotyping of lymphocytes in the lung interstitium and expression of osteopontin and interleukin-2 mRNAs in two different murine models of pulmonary fibrosis

In the surfactant protein C/tumor necrosis factor (SP-C/TNF) transgenic mouse, the TNF-alpha transgene is overexpressed in type II pneumocytes. Pulmonary lymphocytic infiltration develops which is followed by fibrotic changes including accumulation of fibroblasts and deposition of extracellular matrix. We hypothesized that lymphocytes played a role in the development of pulmonary fibrosis in this model. Lymphocytes were recovered from the interstitium of the lung and analyzed by flow cytometry. The absolute number of lymphocytes recovered from transgenic mice were approximately four times of that in littermates. Flow cytometric analysis showed the presence of gamma delta T cells and B1 cells in the former group but these cells were almost absent in the lung of non-transgenic littermates. We also studied lymphocytes accumulating in the lung during bleomycin (BLM)-induced pneumopathy. Serial analyses showed a progressive increase of CD4/CD8 ratio after injection of BLM, reaching a peak at day 14, then decreased to the normal level by day 48. Northern blot analysis of the lung showed an enhanced expression of interleukin (IL)-2 and osteopontin (OPN) mRNA in those two models of pulmonary fibrosis. Expansion of clonal alpha beta T cells as detected by reverse transcriptase-polymerase chain reaction/single strand conformation polymorphism (RT-PCR/SSCP) suggests involvement of antigen-driven mechanisms in the development of pulmonary fibrosis.