Cotton dust-mediated lung epithelial injury

Airway responses to the inhalation of cotton dust and cotton bract extracts

BACKGROUND

Exposure to dust in the cotton industry is associated with respiratory dysfunction. Healthy subjects challenged with cotton bract extract (CBE) develop transient airway hyperresponsiveness. CBE, a major component of cotton dust, is potentially an important agent for studying byssinosis.

OBJECTIVES

To compare airway responses to cotton dust extract (CDE) and CBE in healthy subjects.

METHODS

In 21 healthy, non-smoking subjects we compared the effects of CBE and CDE in a double-blind random order, following a 10-min aerosol inhalation. The response to methacholine (MCh) 2 h following CBE or CDE was measured. Lung function was recorded using maximal (MEFV) and partial expiratory flow volume (PEFV) curves, measuring MEF at 60% of baseline vital capacity below total lung capacity [MEF40%(P)] on the PEFV curve. Responders were subjects who developed a 20% or greater fall in MEF40%(P) following extract challenge. Endotoxin levels were low for CBE (5.71 EU/mg) and CDE (31.88 EU/mg).

RESULTS

There were 18 responders to CBE and 17 responders to CDE. The average maximal falls in MEF40%(P) were 70 +/- 4.9 and 70 +/- 4.4% of baseline (nonsignificant) following CBE and CDE, respectively. All subjects enhanced their MCh response following CBE or CDE. The MCh dose which reduced MEF40%(P) by 40% was identical for CBE and CDE (1.3 microg/ml).

CONCLUSIONS

We conclude that CBE and CDE exert similar physiologic effects.

Apoptotic neutrophils undergoing secondary necrosis induce human lung epithelial cell detachment

Clearance of apoptotic neutrophils by alveolar macrophages plays an important role in the resolution phase of lung inflammation. If not cleared, apoptotic neutrophils are postulated to release histotoxic granular contents. Since numerous cellular proteins are degraded during apoptosis, we sought to determine whether functional serine proteinases are indeed released by apoptosing neutrophils in vitro. In a coculture system, cytokine-activated neutrophils induced detachment in the human epithelial cell line, A549. This process was CD18- and serine proteinase-dependent. Early apoptotic neutrophils induced significant detachment, but live, senescent, resting neutrophils and terminal, secondary necrotic neutrophils had a different effect. This detachment process was CD18-independent but serine proteinase-dependent. Similarly, detachment occurred with primary human small airway epithelial cells. Notably, epithelial cell detachment correlated with the transition of early apoptotic neutrophils to secondary necrosis and with the accumulation of elastase in the supernatant. The membrane integrity of lung epithelial cells was damaged in advance of significant cell detachment. These observations suggest that not only live activated neutrophils but also apoptosing neutrophils can reveal functional elastase activities. Furthermore, the rapidity of the transition emphasizes the importance of the prompt clearance of apoptotic neutrophils before they progress to secondary necrosis at the site of lung inflammation.

Apoptotic neutrophils undergoing secondary necrosis induce human lung epithelial cell detachment

Clearance of apoptotic neutrophils by alveolar macrophages plays an important role in the resolution phase of lung inflammation. If not cleared, apoptotic neutrophils are postulated to release histotoxic granular contents. Since numerous cellular proteins are degraded during apoptosis, we sought to determine whether functional serine proteinases are indeed released by apoptosing neutrophils in vitro. In a coculture system, cytokine-activated neutrophils induced detachment in the human epithelial cell line, A549. This process was CD18- and serine proteinase-dependent. Early apoptotic neutrophils induced significant detachment, but live, senescent, resting neutrophils and terminal, secondary necrotic neutrophils had a different effect. This detachment process was CD18-independent but serine proteinase-dependent. Similarly, detachment occurred with primary human small airway epithelial cells. Notably, epithelial cell detachment correlated with the transition of early apoptotic neutrophils to secondary necrosis and with the accumulation of elastase in the supernatant. The membrane integrity of lung epithelial cells was damaged in advance of significant cell detachment. These observations suggest that not only live activated neutrophils but also apoptosing neutrophils can reveal functional elastase activities. Furthermore, the rapidity of the transition emphasizes the importance of the prompt clearance of apoptotic neutrophils before they progress to secondary necrosis at the site of lung inflammation.

Pulmonary toxicity of dust generated during weaving of carpets

The dust generated during weaving (carpet dust) tibbati, knotted and tuffted carpets in carpet industry was studied for its toxicity in vitro and in vivo. Carpet dust (0.5, 1.0, 2.5 and 5.0 mg/1 x 10(6) cells) caused in vitro cytotoxicity in rat alveolar macrophages (AM) in a concentration-dependent manner. The cytotoxic, inflammatory and oxidative responses were observed in bronchoalveolar lavage fluid (BALF) of rats at 1, 4, 8 and 16 days after exposure. Rats were intratracheally exposed at 5 mg/rat individually to all three types of carpet dust. All types of carpet dusts produced increased AM, lymphocytes (PMN) population in BALF suggesting their inflammatory reactions. Cytotoxic nature of carpet dust was shown by the increased activities of lactate dehydrogenase (LDH) and acid phosphatase (AP) in BALF. Increased AM population and in vitro cytotoxicity due to carpet dusts have shown some correlation with the levels of LDH and AP activities in BALF. The gradual enhanced profile of hydrogen peroxide (H2O2) and nitric oxide (NO) along with depletion of reduced glutathione (GSH) in AM due to these carpet dusts are suggestive of their oxidant nature. The enzyme activities of both glutathione peroxidase (GPx) and glutathione reductase (GR) in AM were marginally reduced in exposed rats. In conclusion, the data suggest the cytotoxic, inflammatory and oxidant nature of carpet dusts. It is extrapolated that health effects on carpet weavers would be associated with the concentration and nature of airborne dust generated during weaving of carpets.

Influence of cigarette smoking on crocidolite-induced ferritin release by human alveolar macrophages

Alveolar macrophages (AMs) mobilize iron from the surface of iron-containing minerals such as asbestos and synthesize ferritin for intracellular iron storage or secretion. Although the synthesis of iron-free ferritin (apoferritin) provides antioxidant protection, the secretion of iron-containing ferritin by AMs could increase the availability of catalytic iron in the lungs. Cigarette smoking may promote the secretion of ferritin by AMs after iron acquisition from mineral sources, because smokers' AMs are iron loaded. The first objective of this study was to determine whether ferritin secretion/release by AMs after in vitro exposure to crocidolite asbestos is enhanced by cigarette smoking. The second objective was to assess whether exogenous ferritin-bound iron could enhance the toxicity of crocidolite to lung cells in vitro. AMs recovered from nonsmokers (n = 8) or smokers (n = 8) were exposed to crocidolite or titanium dioxide (TiO2)(1 x 10(6) AMs, 50 to 200 microg/mL) for up to 18 hours. AMs exposed to crocidolite but not TiO2 showed increased cell content of iron and ferritin and increased cell supernatant ferritin concentrations. Increases in iron and ferritin content were similar for AMs recovered from smokers and those recovered from nonsmokers; however, increases in supernatant ferritin were >7-fold greater for smokers' AMs than for nonsmokers' AMs (P < .001). Exposure of A549 cells, a lung cancer-derived cell line, to crocidolite (50 to 200 microg/mL, 18 hours) caused dose-dependent cell death as indicated by lactate dehydrogenase release. The addition of ferritin (> or = 500 mg/mL) but not apoferritin to culture media enhanced crocidolite-induced LDH release (P < .01). These findings suggest that cigarette smoking and crocidolite exposure have synergistic effects that promote ferritin release by AMs, which could catalyze oxidative injury to other alveolar cells.

Effect of cotton, hemp, and flax dust extracts on lung permeability in the guinea pig

Byssinosis is an occupational lung disease in textile mill workers exposed to the respirable dusts of cotton, hemp, and flax. This study investigated the influence of aqueous extracts from these dusts on overall lung permeability in the guinea pig as an index of respiratory epithelial damage. Lung permeability was assessed by absorption into blood from the lung of inhaled technetium-99m diethylenetriamine penta-acetate (Tc-DTPA) using gamma-scintigraphy. The half-life for Tc-DTPA absorption (t1/2) was significantly reduced following a 4-week inhalation treatment with cotton, hemp, or flax dust extracts when compared to saline control. There was at least a partial return to normal permeability 7 days after stopping treatment. A single inhalation of extract did not affect the t1/2, but increased the number of neutrophils in bronchoalveolar lavage fluid 24 h postexposure. Neutrophil migration into the airspaces therefore appeared to precede the increased lung permeability. Long-term exposure was not associated with respiratory epithelial shedding, suggesting that the increased permeability reflects a loss of epithelial tight junction integrity arising from repeated exposure to as yet undefined agents in these dusts.

Role of the lung in accumulation and metabolism of xenobiotic compounds--implications for chemically induced toxicity

The mammalian lung is exposed to and affected by many airborne and bloodborne foreign compounds. This review summarizes the role of lung in accumulation and metabolism of xenobiotics, some of which are spontaneously reactive or are metabolically activated to toxic intermediates. The specific architectural arrangement of mammalian lung favors that so-called pneumophilic drugs are filtered out of the blood and are retained within the tissue as shown in particular for amphetamine, chlorphentermine, amiodarone, imipramine, chlorpromazine, propranolol, local anaesthetics, and some miscellaneous therapeutics. There is strong evidence that intrapulmonary distribution activity and regulation of drug-metabolizing enzymes in lung is distinct from liver. This review focuses on the metabolic rate of selected compounds in lung such as 5-fluoro-2'-deoxyuridine, local anesthetics, nicotine, benzo(alpha)pyrene, ipomeanol, 4-methylnitrosamino-1-(3-pyridyl)-1-butanone. It is widely accepted that the formation of radical species is a key event in the pneumotoxic mechanisms induced by bleomycin, paraquat, 3-methylindole, butylhydroxytoluene, or nitrofurantoin. Finally, methodological approaches to assess the capacity of lung to eliminate foreign compounds as well as biochemical features of the pulmonary tissue are evaluated briefly.

Woodworkers' exposure to tannins

The tannin concentration of hard- and soft-wood dust was determined in dust powder and in samples on filters. It varied from 1.6 +/- 0.3 mg g-1 (+/- SD) for fir, which is a soft wood, to 80 +/- 30 mg g-1 (+/- SD) for oak, which is a hard wood. The low detection limit of the spectrophotometric method (1.5 micrograms per sample) made the analysis possible with no interference from cellulose ester filters. In five woodworking shops the concentrations of the total dust varied from 0.2 to 20 mg m-3, while those of tannins varied from 2 to 341 micrograms m-3. As hard woods like oak or mahogany have a higher tannin concentration than soft woods, tannin concentration analysis in wood dust can be used as an indicator of exposure to hard-wood dust.

Tannin content of tea and coffee

The tannin content of over-the-counter Indian tea, of green coffee beans and of the roasted coffee beans prepared from the same green beans was determined with a radial diffusion-protein precipitation technique and with a spectrophotometric method. The green beans contained 6.6 +/- 0.6 mg g-1 weight tannic acid equivalents as found by protein precipitation (n = 5, +/- SD) or 6.8 +/- 2.3 mg g-1 by spectrophotometry. The same figures for roasted beans were 18 +/- 1.7 and 17 +/- 2.7 mg g-1, respectively. Tea contained 37 +/- 2.6 mg g-1 weight tannic acid equivalents as analysed by spectrophotometry and 24 +/- 2.8 mg g-1 by the protein precipitation technique. The latter finding may show that the biological reactivity of tannins is variable, although no major changes in the tannin-precipitated albumin occurred as shown by electrophoretic analysis. Both methods provide an easy analysis of the reportedly carcinogenic plant tannins.

Cotton condensed tannin: a potent modulator of alveolar macrophage host-defense function

Alveolar macrophages are the resident airway cells primarily responsible for the protection of the lungs against inhaled toxins and other biologically active material. A number of functional capabilities constitute their host-defense function. They can phagocytize and inactivate foreign material by production of reactive oxygen intermediates or the action of hydrolytic enzymes. In the absence of phagocytosis, macrophages can secrete reactive oxygen intermediates or enzymes that inactivate extracellular biologically active material. They also can secrete metabolites of arachidonic acid and other cytokines that contribute to the inflammatory response of the lungs. Macrophages also secrete a variety of peptide and lipid chemotactic factors that lead to the recruitment of other inflammatory cells into the airways. The condensed tannins, which constitute a significant percentage of the water soluble compounds present in respirable cotton mill dust, dramatically alter the host-defense function of alveolar macrophages in vitro. Tannin inhibits both phagocytosis and production of reactive oxidants in a dose-dependent manner with EC50's of 16 micrograms/mL and 3 micrograms/mL, respectively. This inhibition dramatically decreases the ability of resident alveolar macrophages to clear and detoxify potentially harmful inhaled particles. However, at similar concentrations, tannin stimulates the dose-dependent secretion (EC50 = 15 micrograms/mL) of a low molecular weight lipid neutrophil chemotactic factor that could result in an inflammatory reaction with the recruitment of neutrophils into the lungs. At slightly higher concentrations, tannin promotes the dose-dependent release of arachidonic acid from the macrophage membranes (EC50 = 65 micrograms/mL), which could also contribute to the local inflammatory reaction. Finally, tannin also causes secretion of the cytokine, interleukin-1, from the monocyte precursors of macrophages with an EC50 of 32 micrograms/mL. Interleukin-1 has been implicated as one of the causative agents in the development of fever.

In vitro studies of mechanisms of lung injury in the rodent

In order to better define the responses of lung cells to potentially pathogenic insults, primary cell cultures of dissociated respiratory epithelial cells have been established. These epithelial cells have been obtained from various areas of the respiratory tract ranging from the trachea to the alveolus and the cultures have been demonstrated to mimic the differnetiated state of these cell types as observed in situ. Several procedures which enhance the differentiated state have been evaluated, which include maintenance on more physiologically-relevant substrata, such as collagen gels, use of defined serum-free medium and use of air/liquid interface systems. These approaches have allowed intracellular responses of respiratory epithelium to toxic insult to be better defined.

Signal transducing mechanisms in human platelets stimulated by cotton bract tannin

Cotton bract tannin is a potent stimulus for platelet aggregation and secretion. Tannin has been shown to stimulate the phosphorylation of two 19-kD and 47-kD cytosolic proteins in platelets, but earlier steps in signal transducing mechanisms of platelet activation are unknown. In this study, measurements of 32P-labeled phospholipids, 14C-labeled arachidonic acid, and levels of intracellular free calcium (Ca2+) were performed before and after the addition of thrombin (1 U/ml) or various concentrations of tannin to human platelets. The results showed that tannin induced a dose-dependent synthesis of phosphatidic acid, an early and transient hydrolysis of phosphatidylinositol monophosphate and bisphosphate, a transient synthesis of diacylglycerol, and a release of arachidonic acid metabolites. The kinetics of phosphatidic acid, diacylglycerol, and arachidonic acid metabolite synthesis were similar after platelet stimulation by tannin (75 micrograms/ml) or thrombin. Tannin also induced a reversible rise of intracellular Ca2+ due to a mobilization of the internal stores and an influx of extracellular Ca2+. These results suggest that cotton bract tannin, as thrombin, activates human platelets by phospholipase C and A2 activations, release of diacylglycerol, and mobilization of intracellular free Ca2+.

Modulation of inflammatory cell function by cotton bract tannin: changes in the capacity of alveolar macrophages and neutrophils to produce hydrogen peroxide

Inhalation of cotton mill dust leads to the development of the occupational lung disease byssinosis in a portion of the exposed workers. Condensed tannins present in the dust have biologic activities consistent with the hypothesis that they are one of the etiologic agents for the disease. Inhalation of either cotton dust or tannin provokes an acute inflammatory response characterized by the influx of neutrophils into the airways. The secretion of a low-molecular-weight, lipid neutrophil chemotactic factor from the alveolar macrophages in response to tannin stimulation appears to be important in this inflammatory process. In these studies, the effect of tannin the ability of alveolar macrophages and neutrophils to produce hydrogen peroxide was examined. Low concentrations of tannin itself induced a modest production of hydrogen peroxide from conditioned rabbit alveolar macrophages, while higher concentrations failed to induce peroxide production. In the presence of an independent stimulator of peroxide production (concanavalin A), tannin inhibited peroxide production at all concentrations examined. Aqueous extracts of cotton mill dust (CDE) had an identical effect on peroxide production in a manner that indicated that the tannin present in the dust was responsible for the effect. Like its direct effect on macrophage peroxide production, tannin induced modest peroxide production in human neutrophils. However, unlike its effect on macrophages, tannin enhanced the peroxide production induced by the presence of an independent stimulator (phorbol myristate acetate). CDE had a similar effect on peroxide production, but the dose-response curves suggested that only the high-molecular-weight polymers of tannin present in the CDE were able to enhance peroxide production.(ABSTRACT TRUNCATED AT 250 WORDS)

Inflammation in the lungs of rats after deposition of dust collected from the air of wool mills: the role of epithelial injury and complement activation

In a previous study assessing respiratory symptoms in individuals employed in wool textile mills in the north of England relations between symptoms of chronic bronchitis, breathlessness and wheeze, and rhinitis and current exposure to airborne mass concentration of dust were shown. As preliminary steps in defining the potential hazard associated with dust from the air of wool mills the ability of inspirable dust, collected from the air of wool textile mills, to cause inflammation when injected into the lungs of rats was determined. Dusts were collected from the beginning of wool processing (opening) in one factory and from the middle (combing) and late (backwinding) stages of the process in two other factories. Ability of the dusts to cause inflammation was assessed by instillation into the lungs of rats followed by bronchoalveolar lavage. All the dusts caused some inflammation which peaked on day 1 and did not persist beyond one week. A distinctive aggregation response of mononuclear cells in the lavage, however, had a different time course, peaking at day 7. An attempt was made to determine how the wool mill dusts caused inflammation and experiments showed that the dusts themselves had no inherent chemotactic activity but that they did have a pronounced ability to generate chemotaxins in serum and so could activate complement in lung fluid. In addition, dust collected from ledges in the mills had the ability to injure epithelial cells in vitro which could also contribute to inflammation. A role for endotoxin in the inflammatory activity of the dusts was not discounted and a leachate of the dust had the ability to cause inflammation when injected into the lungs of rats. Wool mill dust is likely to be a complex mixture of materials and these experiments represent a preliminary approach to understanding the biological activity of the whole unfractionated dust and further studies are in progress to define more accurately the toxic material(s) in the dust.

Relationship of byssinosis to the generation of oxygen radicals by bract tissues of cotton plants

Byssinosis is a hazardous respiratory disorder of workers in natural fiber processing industries and, in the case of cotton, is caused by exposure to respirable dust generated from leafy trash associated with raw fibers. To understand the chemical characteristics of involucral trash components that might contribute to bysinosis, we examined the human airway constricting activity and oxygen radical generating activity of dry, frost-killed cotton bracts. In response to inhalation of aerosolized bract extracts, the expiratory flow rates of human volunteers at 40% of vital capacity during partial forced expiration decreased by 3 to 32%. These values enabled us to identify two potentially byssinogenically active bract specimens, a specimen virtually inactive, and a fourth intermediately so. Using spin trapping techniques of electron spin resonance spectrometry, we found that all specimens catalyzed the generation of hydroxyl (preponderantly) and superoxide radicals from hydrogen peroxide. However, the weakest constrictor was the most potent catalyst, and vice versa. This was consistent with transition metal content of the specimens; the most potent catalyst also contained the largest amounts of those metals, suggesting a Fenton-type reaction mechanisms. Other possibilities for the inverse relationship of airway constricting (byssinogenic) activity with oxygen radical generation are discussed. We also found that neither aflatoxin nor endotoxin, contingent contaminants of bracts, catalyzed oxygen radical production from hydrogen peroxide.

Tannin mediated alveolar macrophage protein phosphorylation

Experiments were designed to determine if cotton bract tannin, a component of cotton mill dust, would promote the phosphorylation of alveolar macrophage proteins in doses potentially achievable in vivo. Rabbit alveolar macrophages were loaded with 32PO4 and challenged with various doses of tannin for time periods ranging from two seconds to 120 minutes. Changes in protein phosphorylation began after two seconds and were maximal at five to fifteen minutes. Dose response studies using an exposure time of one hour showed phosphorylation changes began at 1 micrograms/mL and were maximal at 10 to 30 micrograms/mL. Phosphorylation changes were similar to but not identical to those induced by the protein kinase C activator, phorbol myristate acetate (PMA). Calcium ionophore, A-23187 had no clear effect either alone or in conjunction with PMA. These results indicate that cotton bract tannin is able to rapidly promote protein phosphorylation of alveolar macrophages at doses potentially achievable in vivo. Other mechanisms in addition to those of protein kinase C appear to be involved in this protein phosphorylation process.

The toxicity of constituents of cedar and pine woods to pulmonary epithelium

Occupational exposure to cedar and pine woods and pine resin (colophony) can cause asthma and chronic lung disease. Prior studies suggest that plicatic and abietic acids are responsible for the asthmatic reactions that occur in cedar-wood and colophony workers; however, the etiologic mechanism(s) of the chronic lung disease is unknown. To determine if plicatic acid from cedar wood and abietic acid from pine resin could directly damage lung cells, we exposed monolayers of rat type II and human A549 alveolar epithelial cells, intact rat lungs, and rat tracheal explants to solutions of plicatic and abietic acids. As indices of injury, we measured lysis of alveolar epithelial cells with a 51Cr technique, quantitative desquamation of epithelial cells from tracheal explants, and histologic alterations in tracheal explants and intact lungs. Plicatic and abietic acids both caused dose- and time-dependent lysis of alveolar epithelial cells. Instillation of plicatic and abietic acids into rat lungs produced bronchial epithelial sloughing. Abietic acid also caused destruction of the alveolar epithelium. The addition of either acid to rat tracheal explants caused epithelial desquamation that was dose- and time-dependent. Our results suggest that plicatic acid, a unique constituent of cedar wood, and abietic acid, the major constituent in pine resin, can produce lytic damage to alveolar, tracheal, and bronchial epithelial cells. We hypothesize that repeated occupational exposure to these substances might promote the chronic lung damage observed in some cedar- and pine-wood workers and in electronic workers exposed to colophony.

Bronchial responsiveness after inhalation of cotton bract extract

This study examined nonspecific airway responsiveness to methacholine (MC) after inhalation of cotton bract extract (CBE). In a randomized double-blind, crossover trial, 13 healthy volunteers underwent an MC inhalation challenge test prior to inhalation of CBE and normal saline solution (NSS) aerosol sham as well as 2, 8, 24, and 168 h (7 days) later. The response parameter was the concentration of MC required to induce a 25% decrement in the maximal expiratory flow at 40% of the vital capacity below total lung capacity on the partial expiratory flow-volume curve (PC25MEF40%(P]. Five of 13 subjects demonstrated a ventilatory response to CBE with a 20% or larger decrement in the MEF40%(P); no subject demonstrated such change with NSS. For the group, the maximal decrement in MEF40%(P) was to 76.5 +/- 20.3% of baseline (mean +/- SD), occurring approximately 60 to 90 min after provocation, whereas the largest decrement after normal saline was to 88 +/- 10.6% of baseline, occurring immediately after inhalation. Changes in airway responsiveness to MC were transient. For example, the PC25MEF40%(P) for the group (mean +/- SD) was 51.3 +/- 41.1 mg/ml at baseline and 25.8 +/- 30.3 and 52.2 +/- 57.3 mg/ml at 2 and 8 h. After a pre-sham baseline of 50.4 +/- 43.2 mg/ml, PC25MEF40%(P) was 57.6 +/- 83.8 and 153.8 +/- 148 mg/ml at 2 and 8 h. Repeated measures ANOVA on these acute, same-day changes (i.e., 2 and 8 h after provocation) demonstrated a statistically significant effect of CBE on airway responsiveness (p = 0.048). These data demonstrate that inhalation of CBE, in addition to bronchospasm, causes a transient increase in airway responsiveness.

Evaluation of the contribution of tannin to the acute pulmonary inflammatory response against inhaled cotton mill dust

Anesthetized, intubated, and mechanically ventilated rabbits were exposed to aerosolized saline, cotton dust extract (CDE), or tannin for 5 minutes and lavaged 4 hours after exposure. Cell numbers and types present in the bronchoalveolar lavage fluid (BALF) were determined and the concentrations of thromboxane A2 (TxA2) and prostaglandin F2-alpha (PGF2-alpha) in the BALF were also analyzed. The saline control animals had increased numbers and percentage of polymorphonuclear leukocytes (PMN) in the BALF as well as increased levels of TxB2 and PGF2-alpha compared with unexposed animals. Exposure to CDE further increased the number and percentage of PMN and the level of PGF2-alpha but had no effect on TxA2 levels when compared with control animals. Tannin exposure increased PGF2-alpha levels to the same extent as CDE exposure. PMN also increased but to a lesser extent than with CDE. These results indicate that the inflammatory response to CDE is only partially due to the tannin present in CDE.