Biomedical subjects

R Hällgren

Publications and source records attributed to R Hällgren.

At least 109 records · Page 6Linked to original sources

PubMed1990

Signs of increased leakage over the jejunal mucosa during gliadin challenge of patients with coeliac disease.

Intestinal secretion rates of albumin, hyaluronan, and beta 2-microglobulin (beta 2-micro) were determined under basal conditions and after gliadin challenge of coeliac patients and healthy controls by the use of a jejunal perfusion technique. A new tube system was used where a jejunal segment is isolated between balloons and then perfused with a balanced salt solution. Under basal conditions the secretion rate of albumin was similar in the patients and controls while the secretion rate of the glycosaminoglycan hyaluronan, a high molecular weight connective tissue component, was increased more than two times in coeliac patients. Beta 2-micro was secreted in on average three-fold rates in coeliacs compared with controls. All three substances were secreted at a higher rate in patients with active disease than in those with inactive disease defined by morphological damage in small bowel biopsies. The concentrations in jejunal perfusion fluids relative to serum levels in the coeliac patients were for albumin 0.0007, beta 2-micro 0.10, and for hyaluronan 1.94. Challenge with a single dose of gliadin into the jejunal segment gave within 60 min a significant, about two-fold, increase of the secretion rates of all three measured substances. The appearance of hyaluronan could reflect a gliadin induced mucosal oedema with an enhanced leakage from the interstitial/lymph fluid, rich in this glycosaminoglycan. The observed parallel increases in the jejunal secretion of albumin and beta 2-micro after gliadin challenge are best explained by a similar mechanism.

Adult↗

PubMed1990

A mast cell secretagogue, compound 48/80, prevents the accumulation of hyaluronan in lung tissue injured by ionizing irradiation.

Irradiation with a single dose of 30 Grey on the basal regions of the lungs of Sprague-Dawley rats induced a peribronchial and alveolar inflammation. Infiltration of mast cells in the edematous alveolar interstitial tissue and also in the peribronchial tissue were characteristic features of the lesion. The appearance of mast cells was already seen 4 wk after irradiation and by weeks 6 to 8 there was a heavy infiltration. The staining properties suggested that they were connective tissue-type mast cells. The infiltration of mast cells was paralleled by an accumulation of hyaluronan (hyaluronic acid) in the alveolar interstitial tissue 6 and 8 wk after irradiation. The recovery of hyaluronan (HA) during bronchoalveolar lavage (BAL) of the lungs also increased at this time. Treatment with a mast cell secretagogue, compound 48/80, induced a distinct reduction of granulated mast cells in the alveolar tissue. Regular treatment with compound 48/80 from the time of irradiation considerably reduced the HA recovery during BAL and the HA accumulation in the interstitial tissue but did not affect the interstitial infiltration of mononuclear cells and polymorphonuclear leukocytes. By contrast, an accumulation of HA in the alveolar interstitial space was induced when compound 48/80 was given not until mast cell infiltration of the lung had started. The effects of compound 48/80 indicate that the connective tissue response after lung irradiation is dependent on whether or not mast cell degranulation is induced before or after the mast cell infiltration of the alveolar tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Accumulation of hyaluronan (hyaluronic acid) in myocardial interstitial tissue parallels development of transplantation edema in heart allografts in rats.

By using biotin-labeled proteoglycan core protein, hyaluronan (hyaluronic acid; HA) was visualized in rat heart grafts at different times (2, 4, and 6 d) after transplantation. In normal, nontransplanted hearts HA was present in the adventitia of arteries and veins and in the myocardial interstitial tissue. An increased accumulation of HA was evident in the edematous interstitial tissue, infiltrated with lymphocytes, on day 4 after allogeneic transplantation, and was even more pronounced by day 6. No apparent increase in HA was seen in syngeneic grafts. Biochemical assay of HA in heart tissue demonstrated that the myocardial content of HA had increased 60% by day 2 after transplantation in allogeneic as well as syngeneic grafts, indicating that surgical trauma may induce some HA accumulation in heart grafts. The extractable amount of HA declined during the following days in the syngeneic grafts, but increased progressively during the development of rejection in the allogeneic grafts, and increased on average three times by day 6. The relative water content also increased progressively during rejection of allogeneic grafts and correlated with the HA accumulation. The interstitial accumulation of HA, a glycosaminoglycan with unique water-binding qualities, is presumably implicated in the development of interstitial edema during rejection of heart grafts.

Animals↗

PubMed1990

High-dose corticosteroids during bleomycin-induced alveolitis in the rat do not suppress the accumulation of hyaluronan (hyaluronic acid) in lung tissue.

A single intratracheal injection of bleomycin in rats induced, 4 days later, a considerable accumulation of hyaluronan (hyaluronate, hyaluronic acid) in the lung tissue. This connective tissue reaction was quantified biochemically by analysing hyaluronan (HA) in bronchoalveolar lavage fluid (BAL) and lung tissue extracts. The molecular weight of the HA recovered during lavage was 0.2-0.3 X 10(6) daltons. The HA accumulation was related to an increase in lung water content and associated with an increased influx of eosinophils, neutrophils and lymphocytes into BAL fluid. High-dose corticosteroid treatment (prednisolone 15 mg.kg-1 bw per day) to bleomycin injured rats had no effect on the lung tissue content of HA, the recovery of HA during BAL or the molecular weight of HA accumulated in the alveolar space. Furthermore, steroids did not influence the increased lung water content, or the appearance of inflammatory cells in lavage fluid. These findings indicate that the early connective tissue response to the bleomycin lung injury is mediated by a mechanism which is unaffected by systemic high-dose corticosteroids.

Adrenal Cortex Hormones↗

PubMed1990

Accumulation of hyaluronan in bronchoalveolar lavage fluid is independent of iron-, complement- and granulocyte-depletion in bleomycin-induced alveolitis in the rat.

Previous studies on bleomycin-induced alveolitis in rats have demonstrated a transient histological accumulation of hyaluronan (hyaluronate or hyaluronic acid) in the alveolar interstitium, corresponding to increases in hyaluronan (HA) levels in bronchoalveolar lavage (BAL) fluid and lung tissue extracts. The accumulation of HA was related to the influx of inflammatory cells, especially polymorphonucleated cells (PMNs) in BAL fluid and the increase in lung water. In this study we have investigated the influence of iron, complement and PMN dependent mechanisms on the early connective response of the lung in the bleomycin rat model. Iron depletion had no effect on HA or the cellular composition of lavage fluid recovered on day 4 post bleomycin. Treatment of bleomycin-injured rats with cobra venom factor (CVF), totally neutralized complement haemolytic activity but had no effect on lavage HA or the cell invasion in BAL. Treatment with anti-neutrophil serum (ANS), reduced blood and lavage PMN by 70-80%, but had no influence on HA levels in BAL. These results suggest that regulatory mechanisms other than those dependent on iron, complement activation or PMN recruitment are responsible for HA accumulation in this fibrosing alveolitis animal model.

Animals↗

PubMed1990

Cutaneous polyarteritis nodosa associated with Crohn's disease. Report and review of the literature.

A 31-year-old white woman with biopsy verified cutaneous polyarteritis nodosa diagnosed in 1981, developed 6 years later recurrent abdominal pains, rectal bleeding and weight loss. Barium enema demonstrated typical changes of Crohn's disease with fistula in the terminal ileum. Her resected ileum showed granulomatous transmural ileitis without vasculitis. Only corticosteroids and cyclophosphamide controlled the cutaneous and the gastrointestinal symptoms until she was treated with sulfasalazine. The association between cutaneous polyarteritis nodosa and Crohn's disease is discussed and the treatment of earlier reported cases is reviewed.

Adrenal Cortex Hormones↗

PubMed1989

Cold-induced reversible myocardial ischaemia in systemic sclerosis.

The effect of cold provocation on myocardial perfusion was studied in 21 patients with systemic sclerosis and 8 healthy controls. The cold provocation was designed not to cause a pain reaction, and no rise in heart rate/blood pressure product occurred during provocation. Myocardial perfusion was assessed by measurement of thallium uptake by imaged single photon emission computed tomography. No patient had clinical evidence of cardiac involvement, but abnormal electrocardiographic (ECG) findings were found in 5. In 12 patients cold-induced reversible perfusion defects were found; 9 of these also had permanent defects. A further 3 patients had permanent perfusion defects but no reversible defects. The permanent and/or reversible perfusion defects were not related to age among the patients and were not seen in any of the healthy controls, whose age distribution was similar. The reversible and permanent defects were not related to other features of systemic sclerosis, nor to the ECG findings. It is concluded that abnormalities in myocardial perfusion are common in systemic sclerosis and may be present without apparent clinical myocardial involvement. A cold-induced vasopastic process in the myocardial circulation might contribute to the development of the patchy myocardial fibrosis seen in patients with systemic sclerosis.

Adult↗

PubMed1989

Metal content of neutrophil granules is altered in chronic inflammation.

The mass fraction of certain elements was measured in isolated granulocytes and isolated granulocyte granule fractions from patients with active inflammatory arthritides (N = 6) and healthy controls (N = 6). The patients had significantly increased amounts of Ca in the granulocytes, in the specific and light azurophil granules, but normal Ca amounts in the dense azurophil granules. Sr was below the detection limit in the granulocytes and granule fraction from controls, but it appeared in high concentrations in the granulocytes and all granule fractions from the patients. The patients had considerably increased granulocyte amounts of Mn but only slightly increased Mn concentrations in the specific granules. Mn was not detectable in azurophil granules from patients and controls. A prominent accumulation of Fe was seen in the granulocytes from the patients, together with an Fe accumulation in the specific granules. Fe was below the detection limit in azurophil granules from patients and controls. The patients had reduced granulocyte Zn and reduced amounts of Zn in the dense and light azurophil granules but normal Zn amounts in the specific granules. The results obtained indicate that the granulocyte accumulation of Ca, Sr, and Fe observed during chronic inflammation is associated with corresponding granule accumulation of these metals; the considerable Mn accumulation in granulocytes during inflammation is not localized in their granules; and the granule subpopulations differ in their capacity to store certain metals.

Arthritis↗

PubMed1989

Neutrophil and eosinophil involvement of the small bowel in patients with celiac disease and Crohn's disease: studies on the secretion rate and immunohistochemical localization of granulocyte granule constituents.

PURPOSE: The concentrations of myeloperoxidase (MPO), a neutrophil granule constituent, and eosinophil cationic protein (ECP), a specific eosinophil granule protein, were measured in jejunal perfusion fluid in an attempt to elucidate the neutrophil and eosinophil involvement of the small bowel in health and disease. PATIENTS AND METHODS: The control group consisted of 14 males and two females. Ten patients (seven males and three females) with Crohn's disease and seven patients (two males and five females) with celiac disease were also studied; in addition, one patient with relapsing giardiasis, one patient with giardiasis and complete absence of plasma cells in small intestinal lamina propria, and one patient with selective IgA deficiency and no IgA plasma cells in duodeno-jejunal lamina propria were evaluated. Segmental perfusion of the jejunum was performed according to a previously described method. MPO and ECP were measured by radioimmunoassays. RESULTS: In healthy control subjects, the concentrations of both granule proteins were in a narrow range and much higher than would have been anticipated from passive leakage from circulating blood. In patients with celiac disease, the perfusion fluid concentrations of MPO and ECP were on average 3.5 and eight times, respectively, higher than the values seen in the controls. The jejunal segment perfused in patients with Crohn's disease was endoscopically and histologically normal. The perfusion fluid concentrations of MPO and ECP were increased 3.5 and two times, respectively, compared with that in the control subjects. Both patient groups and the control group had similar perfusion fluid concentrations of albumin. Data on MPO and ECP expressed as jejunal secretion rates gave the same differences between patients and controls as just described for the jejunal fluid concentrations. Immunohistochemical studies of jejunal biopsy specimens from another group of patients with celiac disease demonstrated a prominent extracellular deposit of ECP in the lamina propria of the atrophic intestinal mucosa, whereas the release of neutrophil constituents (cathepsin G, MPO) was scarce. In Crohn's disease, an extracellular degranulation of ECP and, to a lesser extent, of cathepsin G was observed in relation to ulcerations only. CONCLUSION: Data obtained indicate that the local release of neutrophil and eosinophil granule components is enhanced in the jejunal tissue from patients with celiac sprue and Crohn's disease. The prominent extracellular deposit of eosinophil granule constituents with cytotoxic properties at the site of inflammatory intestinal lesions in celiac sprue might reflect a pathophysiologic mechanism.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMed1989

Hyaluronic acid and type III procollagen peptide in jejunal perfusion fluid as markers of connective tissue turnover.

Hyaluronic acid (hyaluronate, HA) and type III procollagen N-terminal peptide were measured in jejunal perfusion fluid in an attempt to elucidate the turnover of connective tissue components in the small bowel in health and disease. In healthy controls (n = 16) the average concentration of hyaluronic acid in jejunal perfusion fluid was 12.2 +/- 2 micrograms/L (mean +/- SEM); the mean serum concentration was 22 +/- 7 micrograms/L. The type III procollagen N-terminal peptide concentration in jejunal fluid was 0.12 +/- 0.02 micrograms/L; the mean serum concentration was 12 +/- 0.7 micrograms/L. The albumin concentration in perfusion fluid was, on average, 0.04% of the serum values. Patients with celiac disease (n = 7) and Crohn's disease (n = 10) had normal serum levels of HA and type III procollagen N-terminal peptide. The jejunal secretion rate of HA was significantly increased in both disease groups and on average about three times higher than that in controls. The secretion rate of type III procollagen N-terminal peptide was not altered in celiac disease but increased more than three times in Crohn's disease. Habitual alcoholics investigated after alcohol withdrawal also had significantly increased jejunal secretion of HA but not of type III procollagen N-terminal peptide. In contrast, patients with alcoholic liver cirrhosis and similar ethanol intake had normal secretion of both substances. The findings of the study indicate that the secretion of HA into the jejunal lumen in health is considerable, possibly reflecting the rapid turnover of the intestinal mucosa. The enhanced jejunal secretion of HA in patients with celiac disease and Crohn's disease may be indicative of enhanced connective tissue response due to inflammation, but signs compatible with enhanced jejunal synthesis of type III collagen are only found in Crohn's disease. The HA secretion data in alcoholics might reflect (a) the active regeneration of the intestinal mucosa when ethanol is discontinued and (b) a possible role of the liver in this activity.

Adult↗

PubMed1989

Increased hyaluronic acid production in lung--a possible important factor in interstitial and alveolar edema during general anesthesia and in adult respiratory distress syndrome.

The tremendous swelling potential of hyaluronic acid (HA) is well established, however, the possible role of HA for interstitial and alveolar edema of the lung during general anesthesia and in adult respiratory distress syndrome (ARDS) has not received attention. Bronchoalveolar lavage (BAL) was therefore performed on 28 apparently lung-healthy patients; first 24 h prior to induction of general anesthesia and then--in the same lung segment--approximately 30 min after anesthesia induction with endotracheal intubation and mechanical ventilation with N2O in O2. The second BAL was undertaken prior to surgery. Another group of 11 patients with ARDS was also subjected to BAL. A third control group of 10 patients was investigated with BAL 24 h apart to see if a prior BAL influenced the second BAL. Prominent findings were that induction of general anesthesia was associated with significantly (P less than 0.001) increased amount of HA in BAL, on average 77 micrograms/l (range 24-181 micrograms/l) as compared with HA-level 24 h before anesthesia, where all values were below 20 micrograms/l. ARDS patients ranged from 72 to 1636 micrograms/l with a mean of 515 micrograms/l, which was significantly (P less than 0.001) higher than HA-level after induction of anesthesia. The control group that had BAL of the same lung segment 24 h apart did not show any increase in HA-level during the second BAL; with HA-level below 20 micrograms/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Challenge with gliadin induces eosinophil and mast cell activation in the jejunum of patients with celiac disease.

PURPOSE: The aim of this study was to clarify the role of eosinophils and mast cells in the small bowel in celiac disease. PATIENTS AND METHODS: Patients with celiac disease (n = 10) were investigated by perfusion of a closed jejunal segment. The concentrations of certain granule constituents from eosinophils, eosinophil cationic protein (ECP), and from mast cells/basophils, histamine, were measured and the jejunal secretion rates of these cellular markers were calculated. RESULTS: Compared with findings in healthy control subjects (n = 14), increased secretion rates were observed under basal conditions in patients with histopathologically active celiac disease. Gliadin, administered by perfusion to the jejunal segment, induced a fourfold increase in ECP secretion and a twofold increase of histamine secretion in patients with celiac disease (n = 7), but did not influence the secretion rates of these substances in healthy controls (n = 3). The secretion rate of ECP started to increase 20 minutes after challenge of the perfused segment with gliadin and reached maximum levels 40 minutes later. The secretion rate of histamine started to increase 40 minutes after gliadin administration. Concurrently with these inflammatory events, the secretion of albumin was doubled as a sign of increased mucosal leakage. CONCLUSION: These data indicate that eosinophils and mast cells are both involved in the early gliadin-induced reactions of the small intestine, and suggest that these cells are effector cells participating in the celiac lesion of the mucosa.

Adult↗

PubMed1989

Hyaluronan and type III procollagen peptide concentrations in bronchoalveolar lavage fluid in idiopathic pulmonary fibrosis.

The connective tissue components hyaluronan (hyaluronic acid) and type III procollagen peptide were measured in bronchoalveolar lavage fluid in 22 patients with idiopathic pulmonary fibrosis and 21 healthy control subjects. The patients with idiopathic pulmonary fibrosis had higher concentrations of hyaluronan (median 46 micrograms/l) and type III procollagen peptide (median 0.45 micrograms/l) than the healthy controls (9 and less than 0.02 micrograms/l; p less than 0.001). The patients had normal serum concentrations of hyaluronan and of the procollagen peptide, and albumin concentrations in lavage fluid similar to those of the control subjects. Neutrophil and lymphocyte counts in lavage fluid were increased on average 10 and two fold respectively in the patients with idiopathic pulmonary fibrosis and both correlated with the amount of hyaluronan recovered (p less than 0.05). An inverse correlation was seen between the transfer factor for carbon monoxide and hyaluronan concentrations in lavage fluid in the patients (p less than 0.05). Deterioration in lung function and radiographic progression were seen over six months in 12 of the patients. These patients had higher lavage fluid concentrations of hyaluronan and type III procollagen peptide than the patients whose disease was stable (p less than 0.01). Increased synthesis of hyaluronan and type III procollagen peptide in lung parenchyma may reflect activation or proliferation (or both) of pulmonary fibroblasts in idiopathic pulmonary fibrosis and seems to be linked to the severity and activity of the lung disease.

Adult↗

PubMed1989

Lung accumulation of hyaluronan parallels pulmonary edema in experimental alveolitis.

The glycosaminoglycan hyaluronan (HA, hyaluronate or hyaluronic acid) was quantified in rat lung during the development of bleomycin-induced lung injury. Extracted lung HA was measured by a radiometric assay. In control rats, the HA lung content was 95 +/- 5 (SE) micrograms/g of freeze-dried and homogenized lung tissue. After a single intratracheal instillation of bleomycin, the HA content of the lung increased significantly on day 1. Peak HA concentrations on days 3-7 averaged 70% higher than normal lung HA concentrations. From day 7 the HA concentrations progressively declined and had returned to normal by day 30. Qualitative assessment of lung HA has previously demonstrated that HA is accumulated in the edematous interstitial alveolar space during the alveolitis phase of bleomycin injury. Since high-molecular-weight HA has unique hydrophilic properties, another aim of the study was to elucidate the possible link between the increase in lung HA and the development of interstitial-alveolar edema postbleomycin. HA recovered by bronchoalveolar lavage from bleomycin-injured lungs increased with increasing total lung HA and had a mean molecular size of 220,000 +/- 50,000 (SE), indicating the minimum size of HA accumulated in the alveolar space. The relative lung water increased significantly on days 3-7 after bleomycin administration. A close relationship (P less than 0.001) and time dependence between the increase in relative lung water and the increase in lung HA were found.

Animals↗

PubMed1989

Increased hyaluronan (hyaluronic acid) levels in bronchoalveolar lavage fluid after histamine inhalation.

Hyaluronan (hyaluronic acid) appears in low concentrations in bronchoalveolar lavage fluid from healthy individuals, while increased amounts have been reported in lavage fluid from patients with interstitial lung diseases and allergic asthma. We have earlier reported a strong correlation between the appearance of lavage fluid mast cells and hyaluronan in patients with sarcoidosis and extrinsic allergic alveolitis. The central role of the mast cell in allergic asthma is well documented. In this study we have investigated if challenge with inhaled histamine, a major mast cell component, could influence the appearance of hyaluronan in bronchoalveolar lavage fluid. A more than twofold increase of hyaluronan was seen 24 h after challenge with histamine. This increase correlated with a less pronounced increase of albumin in lavage fluid. Histamine challenge also induced an increase of mast cells, lymphocytes, and granulocytes in the lavage fluid. The observed histamine effect on the hyaluronan recovery during lavage might be explained by a histamine-mediated leakage of interstitial fluid, rich in hyaluronan, to the alveolar space. Mast cell degranulation of histamine may partly underlie the appearance of increased amounts of hyaluronan in lavage fluid from patients with interstitial lung diseases and allergic asthma.

Adult↗

PubMed1989

The eosinophil component of the alveolitis in idiopathic pulmonary fibrosis. Signs of eosinophil activation in the lung are related to impaired lung function.

The number of eosinophils and the concentrations of eosinophil cationic protein (ECP), a specific granule constituent of eosinophil granulocytes, were measured in bronchoalveolar lavage (BAL) fluid from patients (n = 22) with idiopathic pulmonary fibrosis (IPF). The median recovery of eosinophils during lavage performance was 4% (range, zero to 49) of the nonepithelial cells and significantly increased compared with the recovery in healthy control subjects (less than 1%) and in control patients with sarcoidosis (1%; range, zero to 7). The median BAL fluid concentration of ECP was in IPF 13.3 micrograms/L (range, 2 to 118) and significantly increased compared with the concentrations in healthy control subjects (2.7 micrograms/L; range, less than 2 to 8) and in control patients (6.6 micrograms/L; range, less than 2 to 64). The BAL fluid concentrations of myeloperoxidase (MPO) were also significantly increased in IPF, indicating a local neutrophil activation. A significant correlation was found between BAL fluid ECP and MPO, suggesting a common activator of eosinophils and neutrophils. BAL fluid eosinophils and ECP correlated with the reduced diffusion capacity of the lung but not with vital capacity or forced expiratory volume. It is concluded that eosinophil activation is part of the inflammatory process in IPF. ECP and other cytotoxic eosinophil products may play a pathophysiologic role for the lung damage in this disease.

Adult↗

PubMed1989

Accumulation of hyaluronan (hyaluronic acid) in the lung in adult respiratory distress syndrome.

The concentrations of hyaluronan (HA) were measured in bronchoalveolar lavage (BAL) fluid and serum from 12 patients with adult respiratory distress syndrome (ARDS). The median BAL fluid HA concentration was 353 micrograms/L, about six times higher than that seen in control patients (p less than 0.001). The median serum HA value was 619 micrograms/L, which was a 30-fold increase compared with that in the control patients (p less than 0.001). Another connective tissue component, type III procollagen peptide, was not recovered in significant amounts during lavage in patients with ARDS, but it appeared in the bloodstream in increased concentrations (p less than 0.001). Obtained recovery of HA during lavage of patients with ARDS cannot be explained by an enhanced passive leakage from the bloodstream because of increased alveolar-capillary permeability, but rather could reflect a mobilization of HA from lung interstitial tissue because of hydrostatic mechanisms. Alternatively, the appearance of HA in the alveolar space in ARDS might reflect an enhanced lung synthesis of HA. An increased HA production can possibly be mediated, directly or indirectly, by activated complement components, since a significant relationship was seen between increased plasma concentrations of C3a des Arg and BAL fluid HA (r = 0.61; p less than 0.05). The observed accumulation of HA in the small airways in ARDS may be expected to immobilize water and thereby contribute to the interstitial and alveolar edema. The inverse correlation (r = 0.71; p less than 0.01) seen between BAL fluid HA and pulmonary oxygenation index (PaO2/inspired oxygen fraction) supports such a hypothesis.

Adult↗

PubMed1989

Accumulation of hyaluronic acid in the alveolar interstitial tissue in bleomycin-induced alveolitis.

By using biotin-labeled proteoglycan core protein and an avidin-enzyme system, hyaluronic acid (HA) was visualized in the lungs of rats at different times (4, 10, and 20 days) after bleomycin injury. Four days after an intratracheal injection of bleomycin, HA was accumulated in the edematous alveolar septa of the focal areas with lung tissue injury. An interstitial cellular infiltrate of mainly lymphocytes was present. In normal rat lung, HA was not seen in the alveolar tissue but confined to peribronchial and perivascular spaces. Ten and twenty days after bleomycin administration, increasing numbers of macrophages were apparent in the alveolar space. Proliferating fibroblasts and deposition of collagen in the alveolar tissue were observed while the diffuse HA accumulation was becoming less prominent in the alveolar interstitial tissue. HA was more distinctly located in the surroundings of proliferating fibroblasts. A few scattered alveolar macrophages showed a positive staining for HA. An increased water content of the lung was most apparent 4 days after bleomycin administration. The accumulation of HA, a glycosaminoglycan with unique qualities to immobilize water, in the alveolar interstitium suggests a role for HA in the alveolar interstitial edema. The appearance of HA in alveolar macrophages might indicate that macrophage phagocytosis contributes to the elimination of HA from inflamed lung tissue.

Animals↗