Enhanced expression of Fas Ligand (FasL) in the lower airways of patients with fibrotic interstitial lung diseases (ILDs)

The exact role of FasL, and particularly its soluble and membrane-bound forms, in the development of chronic ILDs and lung fibrosis has not been extensively explored. We aimed at analyzing membrane-bound FasL expression on alveolar macrophages (AM) and lymphocytes (AL) as well as soluble FasL (sFasL) levels in bronchoalveolar lavage (BAL) from ILDs patients, incl. pulmonary sarcoidosis (PS), hypersensitivity pneumonitis (HP), silicosis, asbestosis, idiopathic pulmonary fibrosis (IPF), nonspecific interstitial pneumonia (NSIP), and healthy subjects (n = 89, 12, 7, 8, 23, 6, 17, respectively). In IPF, significantly increased percentage of AM FasL(+) and CD8(+)FasL(+) cells as well as sFasL levels in BAL were found. Increased sFasL levels were also observed in HP. NSIP and asbestosis were characterized by higher AM FasL(+) relative number; CD8(+)FasL(+) population was expanded in asbestosis only. There was a significant decline in AL FasL(+) percentage in PS and HP. Vital capacity was negatively correlated with sFasL levels, AM FasL(+) and CD8(+)FasL(+) cell relative count. CD4(+)FasL(+) and CD8(+)FasL(+) percentage strongly correlated with BAL neutrophilia, an unfavorable prognostic factor in lung fibrosis. The concurrent comparative BAL analysis of FasL expression indicates that FasL(+) AM and AL (mainly Tc cells) comprise an important element of the fibrotic process, mostly in IPF. FasL might play a crucial role in other fibrosis-complicated ILDs, like NSIP and asbestosis.     

Expression of insulin-like growth factor-I (IGF-I) in alveolar macrophages and lymphocytes obtained by bronchoalveolar lavage (BAL) in interstitial lung diseases (ILD). Assessment of IGF-I as a potential local mitogen and antiapoptotic cytokine

Little is known about IGF-I expression in the alveolar lymphocytes (AL), and about local role of IGF-I in physiological conditions and in interstitial lung diseases. Bronchoalveolar lavage was carried out in patients with silicosis, asbestosis, idiopathic pulmonary fibrosis (IPF) and sarcoidosis, as well as in control subjects (n = 13, 9, 12, 56, 15, resp). Alveolar macrophages (AM) and lymphocytes (AL) were studied for (1) IGF-I, BCL-2, Fas and Fas Ligand expression and (2) cell cycle (incl. sub-G1 peak of late apoptosis) with propidium iodide (PI). Flow cytometry (FC) and immunocytochemistry were used. AL early apoptosis was detected by Annexin V FITC/PI staining. IGF-I was present in AL of all tested groups. The number of IGF-I positive AL was significantly higher in IPF (52 +/- 6.7%) and in later (II and III) stages of sarcoidosis (39 +/- 7.8 vs 16 +/- 4.0% in controls, p < 0.05). Increased BCL-2 expression in AL was detected in IPF and sarcoidosis. In all tested groups, AL were almost exclusively Fas+ T cells. Generally, a low number of AL entered apoptosis; no significant differences were found between patient groups, except decreased apoptosis rate in sarcoidosis (0.60 +/- 0.17 vs 1.15 +/- 0.33% in controls, p < 0.05). Proportion of AL positive for IGF-I was significantly correlated with parameters reflecting AL and AM cell proliferation and BCL-2 expression (e.g. AL IGF-I+ vs AM in S phase of cell cycle: r(S) = +0.50, p = 0.001), but not with apoptosis. The results show that human alveolar lymphocytes express IGF-I in normal conditions, as well as in ILD. The proportion of IGF-I+ lymphocytes was significantly increased in IPF and at later stages of sarcoidosis. In our material there was no evidence for profibrogenic or antiapoptotic activity of IGF-I. We suggest that IGF-I originating from AL may be locally active as a mitogen for alveolar macrophages and lymphocytes in ILD.     

Negative allometry of docosahexaenoic acid in the fowl lung and pulmonary surfactant phospholipids

In a recent study (Comp. Biochem. Physiol. B. (2010)155: 301-308) we reported that the fatty acids (FA) of the avian (7 species) total lung phospholipids (PL) (i.e. lung parenchyma and surfactant together) provide allometric properties. To test whether this allometric scaling also occurs in either of the above components, in six gallinaceous species, in a body weight range from 150 g (Japanese quail, Coturnix coturnix japonica) to 19 kg (turkey, Meleagris gallopavo) the PL FA composition (mol%) was determined in the pulmonary surfactant, in native and in thoroughly lavaged lungs (referred to as lung parenchyma). In all three components docosahexaenoic acid (DHA) showed significant and negative allometric scaling (B = -0.056, -0.17 and -0.1, respectively). Surfactant PLs provided further negative allometry for palmitic acid and the opposite was found for palmitoleate and arachidonate. In the lung parenchymal PLs increasing body weight was matched with shorter chain FAs (average FA chain length) and competing n6 and n3 end-product fatty acids (positive allometry for arachidonic acid and negative for DHA). Negative allometric scaling was found for the tissue malondialdehyde concentration in the native and lavaged lungs (B = -0.1582 and -0.1594, respectively). In these tissues strong correlation was found between the MDA concentration and DHA proportion (r = 0.439 and 0.679, respectively), denoting the role of DHA in shaping the allometric properties and influencing the extent of in vivo lipid peroxidation of membrane lipids in fowl lungs.     

RNA interference as a gene silencing therapy for mutant MYOC protein in primary open angle glaucoma

Bronchoalveolar lavage (BAL) is a useful diagnostic tool in interstitial lunge diseases (ILD). However, differential cell counts are often non specific and immunocytochemistry is time consuming. Staining of glyoproteins by periodic acid Schiff (PAS) reaction may help in discriminating different forms of ILD. In addition, PAS staining is easy to perform. BAL cells from patients with idiopathic pulmonary fibrosis (IPF) (n = 8), sarcoidosis (n = 9), and extrinsic allergic alveolitis (EAA) (n = 2) were investigated. Cytospins from BAL cells were made and cells were stained using Hemacolor quick stain and PAS staining. Lymphocytic alveolitis was found in sarcoidosis and EAA whereas in IPF both lymphocytes and neutrophils were increased. PAS positive cells were significantly decreased in EAA compared to IPF and sarcoidosis (25.5% ± 0.7% vs 59.8% ± 25.1% and 64.0% ± 19.7%, respectively) (P < 0.05). No significant correlation between PAS positive cells and inflammatory cells was observed. These results suggest that PAS staining of BAL cells may provide additional information in the differential diagnosis of ILD. Further studies ware warranted to evaluate PAS staining in larger numbers of BAL from patients with ILD.     

Increased levels of free circulating DNA in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is difficult to diagnose because of numerous interstitial lung diseases with similar symptoms. As serum DNA has proven useful for early lung cancer detection, we aimed to define the relevance of this marker in discriminating IPF from other fibrotic and nonfibrotic/nonmalignant lung diseases. DNA was quantified in 191 subjects: 64 healthy individuals, 58 patients with IPF, 17 patients with nonspecific pulmonary fibrosis (13 idiopathic nonspecific interstitial pneumonia, 4 chronic hypersensitivity pneumonitis), and 52 patients with other diffuse/nonmalignant lung diseases. The median value of free DNA in IPF patients was 61.1 ng/mL (range 7.1-405), which was significantly higher than that of healthy donors (median 6.8, range 2.2-184) (p<0.001) and that of patients with other diffuse/nonmalignant lung diseases (median 28.0, range 4.2-281) (p=0.004). The area under the ROC curve was 0.926 (95% CI 0.879-0.973) when IPF patients were compared with healthy donors, and 0.702 (95% CI 0.609-0.796) when a comparison was made with non-IPF pulmonary diseases. In conclusion, we observed significantly higher levels of free circulating DNA in patients with IPF than in those with other fibrotic or diffuse/nonmalignant lung diseases.     

Influence of septic shock upon phosphatidylcholine remodeling mechanism in rat lung

Septic shock in rats lead to pulmonary disorders associated with alterations of phospholipid metabolism. The ratio between phosphatidylcholine and lysophosphatidylcholine is lowered both in lung tissue and in pulmonary surfactant because enzymes of phosphatidylcholine remodeling mechanism are distinctly affected by septic shock. Specific activity of phospholipase A2 is enhanced 5-fold while specific activities of lysolecithin acyltransferase and lysolecithin : lysolecithin acyltransferase are only slightly increased or remain unchanged. Beyond that, palmitic acid content of lung tissue phosphatidylcholine is significantly reduced and replaced mainly by arachidonic acid. The release of this fatty acid by action of phospholipase A2 may lead via intermediates to the generation of potent mediators such as prostaglandins, thromboxane or slow-reacting substance.     

Measurement of MMP-9 and -12 degraded elastin (ELM) provides unique information on lung tissue degradation

ABSTRACT: BACKGROUND: Elastin is an essential component of selected connective tissues that provides a unique physiological elasticity. Elastin may be considered a signature protein of lungs where matrix metalloprotease (MMP) -9-and -12, may be considered the signature proteases of the macrophages, which in part are responsible for tissue damage during disease progression. Thus, we hypothesized that a MMP-9/-12 generated fragment of elastin may be a relevant biochemical maker for lung diseases. METHODS: Elastin fragments were identified by mass-spectrometry and one sequence, generated by MMP-9 and -12 (ELN-441), was selected for monoclonal antibody generation and used in the development of an ELISA. Soluble and insoluble elastin from lung was cleaved in vitro and the time-dependent release of fragments was assessed in the ELN-441 assay. The release of ELN-441 in human serum from patients with chronic obstructive pulmonary disease (COPD) (n = 10) and idiopathic pulmonary fibrosis (IPF) (n = 29) were compared to healthy matched controls (n = 11). RESULTS: The sequence ELN-441 was exclusively generated by MMP-9 and -12 and was time-dependently released from soluble lung elastin. ELN-441 levels were 287% higher in patients diagnosed with COPD (p < 0.001) and 124% higher in IPF patients (p < 0.0001) compared with controls. ELN-441 had better diagnostic value in COPD patients (AUC 97%, p = 0.001) than in IPF patients (AUC 90%, p = 0.0001). The odds ratios for differentiating controls from COPD or IPF were 24 [2.06-280] for COPD and 50 [2.64-934] for IPF. CONCLUSIONS: MMP-9 and -12 time-dependently released the ELN-441 epitope from elastin. This fragment was elevated in serum from patients with the lung diseases IPF and COPD, however these data needs to be validated in larger clinical settings.     

Surface activity following natural surfactant treatment in premature lambs

Premature lambs with respiratory failure [CO2 partial pressure (PCO2) greater than 70 Torr] were treated with 50 mg/kg 3H-labeled natural surfactant by tracheal instillation. Minimum surface tensions of sequential samples suctioned from the airways fell from 25 +/- 3 dyn/cm before treatment to 8 +/- 5 dyn/cm after treatment and again rose to 32 +/- 2 dyn/cm at death. Minimum surface tensions of alveolar wash samples taken at death were 27 +/- 4 dyn/cm, whereas surfactant fractions reisolated from the alveolar washes lowered surface tension to under 10 dyn/cm. The alveolar washes, surfactant reisolated from the alveolar washes, and natural surfactant had similar phospholipid compositions; however, the alveolar washes contained about 40 times more protein per micromole phosphatidylcholine. The natural surfactant used for treatment apparently was inactivated by an inhibitor of surfactant function. After intravenous injections of [14C]palmitic acid, labeled saturated phosphatidylcholine appeared on the airways, indicating endogenous synthesis and secretion. However, the specific activity of the 3H-labeled saturated phosphatidylcholine in the natural surfactant used for treatment decreased by only 30 +/- 4% in the alveolar wash; thus the treatment dose was not diluted to a large extent by endogenous pools.     

The labelling of pulmonary surfactant phosphatidylcholine in 19-31-days-old lambs

The labelling of surfactant phosphatidylcholine and disaturated phosphatidylcholine was studied in 19-31-days-old lambs. Following the placement of small bore tracheal catheters, the animals were given radioactively labelled palmitic acid and/or choline by intravenous injection and multiple samples were recovered from the distal airways of each animal via a small catheter. The specific activities of the phosphatidylcholine and/or disaturated phosphatidylcholine were measured in these samples of surfactant. The labelled phospholipids accumulated in the samples of surfactant in a linear fashion; the mean time required to reach maximal specific activities in phosphatidylcholine and saturated phosphatidylcholine with either palmitic acid or choline as precursor was 28 h. Subsequently the specific activities of the labelled phospholipids from the surfactant samples decreased semi-logarithmically. The mean t1/2 for phosphatidylcholine and disaturated phosphatidylcholine labelled with radioactive palmitic acid was 35 h. The saturated phosphatidylcholine labelled with radioactive choline had a t1/2 of 251 h. The results demonstrate that surfactant labelling studies can be done by multiple sampling of single large animals.     

Altered function of pulmonary surfactant in fatty acid lung injury

To determine whether acute fatty acid lung injury impairs pulmonary surfactant function, we studied anesthetized ventilated rabbits given oleic acid (55 mg/kg iv, n = 11) or an equivalent volume of saline (n = 8). Measurements of pulmonary mechanics indicated a decrease in dynamic compliance within 5 min of injury and a decrease in lung volume that was disproportionately large at low pressures, consistent with diminished surfactant activity in vivo. Bronchoalveolar lavage fluid obtained 1 h after injury had significantly increased erythrocytes and total leukocytes, largely polymorphonuclear cells. The phospholipid content and composition of the cell-free fraction had only minor changes from those of controls, but the protein content was increased 35-fold. Measurements of lavage surface activity in vitro showed an increase in average minimum surface tension from 1.3 +/- 0.4 (SE) dyn/cm in controls to 20.2 +/- 3.9 dyn/cm in injured animals. The alterations in static pressure-volume curves and decrease in lavage surface activity suggest a severe alteration of surfactant function in this form of lung injury that occurs despite the presence of normal amounts of surfactant phospholipids.     

Unilateral radiation pneumonitis in sheep: physiological changes and bronchoalveolar lavage

Radiation pneumonitis is a life-threatening result of therapeutic thoracic irradiation, yet its mechanisms are poorly understood. We studied the effects of unilateral lung irradiation (3,000 rad) in sheep from the immediate response to the later development of radiation pneumonitis. We defined radiation pneumonitis by its diagnostic clinical feature, radiographic infiltration of the irradiated zone with a straight margin corresponding to the radiation port. The immediate response in the few hours after irradiation was characterized by cough, labored respiration, hypoxemia (arterial PO2 decreased 19 Torr), mild pulmonary hypertension (pulmonary arterial pressure increased 20%), and lymphopenia. Hemodynamics and gas exchange returned to normal by day 2 but became abnormal again before or during radiation pneumonitis at 32 +/- 2 days. Respiratory distress, hypoxemia, and pulmonary hypertension recurred during radiation pneumonitis. Bronchoalveolar lavage during radiation pneumonitis contained increased neutrophils (19 +/- 4%, control = 7%), increased protein (0.27 +/- 0.1 g/dl, control = 0.12 +/- 0.03), and severely impaired ability to lower surface tension. Alveolar macrophages from both lungs during unilateral radiation pneumonitis exhibited impaired generation of superoxide after phorbol myristate (only a 30% increase). Normal control alveolar macrophages increased superoxide production after stimulation greater than 400%. We conclude that unilateral lung irradiation in sheep causes a mild immediate response followed by radiation pneumonitis at 1 mo. Unilateral radiation pneumonitis in this model is associated with ipsilateral neutrophilic alveolitis, increased bronchoalveolar lavage protein, and impaired surfactant function, as well as bilateral functional abnormalities of alveolar macrophages.     

The relationship between intra- and extra-cellular surfactant phospholipids in the lungs of rabbits and the effects of silica-induced lung injury.

Extensive homogenization of lung tissue by nitrogen decompression in a Parr disruption bomb increased by 5-fold the yields of low-density phospholipid (d = 1.06) achieved by other methods. This intracellular phospholipid preparation was high in phosphatidylcholines (84.3%), particularly disaturated phosphatidylcholine (51.2%). On the basis of its low density, composition, and morphological appearance, we concluded that this phospholipid was derived from the intracellular compartment of pulmonary surfactant. We examined the relationship between intra- and extra-cellular surfactant pools according to age, gender and silica-induced pulmonary injury. In normal animals the intracellular pool of surfactant phospholipids increased from 1.54 +/- 0.14 mg at 1 day after birth to 62.30 +/- 4.50 mg per pair of lungs after 31 months, and over the same time period the extracellular pool increased from 1.04 +/- 0.15 mg to 27.45 +/- 2.30 mg per pair of lungs. The ratio between the extracellular and intracellular pools of surfactant increased from 1.50 +/- 0.19 at 1 day after birth to 2.28 +/- 0.23 after 31 months of age. The ratio between the two pools was not influenced by gender, but was changed by the intratracheal injection of silica into the lungs. Intratracheal injection of silica dust increased the levels of surfactant in both compartments, but not to the same extent, indicating that the ratio between the pools could be changed by toxic materials. These data suggest the existence of a size relationship between the intra- and the extra-cellular pools of surfactant, a relationship which implies a common regulatory mechanism that can be disturbed during pulmonary injury.     

Glucose effects on lung surfactant kinetics in conscious pigs

The primary goal of this study was to investigate the effects of glucose infusion on surfactant phosphatidylcholine (PC) metabolic kinetics in the lungs. A new stable isotope tracer model was used in which [1,2-(13)C(2)]acetate and uniformly labeled [U-(13)C(16)]palmitate were infused in 12 normal overnight-fasted pigs to quantify lung surfactant kinetics with or without glucose infusion (24 mg. kg(-1). min(-1)). With glucose infusion, the rate of surfactant PC incorporation from de novo synthesized palmitate increased from the control value of 2.1 +/- 0.2 to 15.5 +/- 1.9 nmol PC-bound palmitate. h(-1). g wet lung(-1) (P < 0.05), whereas the incorporation rate from plasma preformed palmitate decreased from the control value of 20.9 +/- 1.9 to 11.6 +/- 1.1 nmol palmitate. h(-1). g wet lung(-1) (P < 0.05). The palmitate composition in lamellar body surfactant PC increased from the control value of 61.7 +/- 2.1% to 75.9 +/- 0.6% (P < 0.05). The surfactant PC secretion rate decreased from the control value of 239.0 +/- 26.1 to 81.9 +/- 5.3 nmol PC-bound palmitate. h(-1). g wet lung(-1) (P < 0.05). We conclude that, whereas surfactant secretion was inhibited by glucose infusion, neither total surfactant PC synthesis nor the surfactant PC pool size was significantly affected due to an increased reliance on de novo synthesized fatty acids.     

The Na+/H+ antiporter in rat alveolar type II cells and its role in stimulated surfactant secretion

We used the pH-sensitive fluorescent probe 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) to identify Na+/H+ exchange in freshly isolated rat alveolar type II cells and alveolar type II cells in primary culture. The intracellular pH (pHi) of freshly isolated alveolar type II cells was 7.36 +/- 0.05 (n = 3). When freshly isolated alveolar type II cells were acid loaded with nigericin in sodium-free buffer, the pHi dropped to 6.59 +/- 0.04 and remained low in sodium-free buffer. When acid-loaded cells were subsequently incubated with NaCl, pHi increased in a dose-dependent manner. Amiloride (0.1 mM) inhibited the sodium-induced increase in pHi. When the acid-loaded cells were resuspended in an unbuffered choline chloride solution, the cells secreted H+ in a sodium-dependent and amiloride-inhibitable manner. Alveolar type II cell monolayers, which were cultured for 22 h on glass coverslips and then loaded with BCECF, had a resting pHi of 7.48 +/- 0.05 (n = 4). Nigericin acidified these cultured cells in the absence of sodium and NaCl increased the pHi of these acid loaded cells as observed in freshly isolated cells. Secretagogues of pulmonary surfactant, 12-O-tetradecanoylphorbol 13-acetate (TPA) and terbutaline, did not change pHi. Inhibition of the Na+/H+ antiporter by the addition of amiloride to a Na+ containing medium or the substitution of choline for Na+ did not inhibit stimulated phosphatidylcholine secretion. We conclude that pHi regulation in rat alveolar type II cells is in part mediated by an amiloride-sensitive Na+/H+ antiporter, but this system appears not to be involved in TPA- or terbutaline-induced pulmonary surfactant secretion in primary culture.     

Differential effects of saturated fatty acids on low density lipoprotein metabolism in the guinea pig.

Studies have shown that dietary fat saturation affects guinea pig plasma low density lipoprotein (LDL) levels by altering both LDL receptor-mediated catabolism and flux rates of LDL (Fernandez et al. 1992. J. Lipid Res. 33: 97-109). The present studies investigated whether saturated fatty acids of varying chain lengths have differential effects on LDL metabolism. Guinea pigs were fed 15% (w/w, 35% calories) fat diets containing either palm kernel oil (PK), 52% lauric acid/18% myristic acid; palm oil (PO), 43% palmitic acid/4% stearic acid; or beef tallow (BT), 23% palmitic acid/14% stearic acid. Plasma LDL cholesterol levels were significantly higher for animals fed the PK diet (P < 0.001) with values of 83 +/- 19 (n = 12), 53 +/- 8 (n = 12) and 44 +/- 16 (n = 10) mg/dl for PK, PO, and BT diets, respectively. The relative percentage composition of LDL was modified by fat type; however, LDL diameters and peak densities were not different between diets, indicating no effect of saturated fatty acid composition on LDL size. ApoB/E receptor-mediated LDL fractional catabolic rates (FCR) were significantly lower in animals fed the PK diet (P < 0.01) and LDL apoB flux rates were reduced (P < 0.01) in animals fed the BT diet. A correlation was found between plasma LDL levels and receptor-mediated LDL catabolism (r = -0.66, P < 0.01). A higher apoB/E receptor number (Bmax), determined by in vitro LDL binding to guinea pig hepatic membranes, was observed for animals fed BT versus PK or PO diets and Bmax values were significantly correlated with plasma LDL levels (r = -0.776, P < 0.001). These results indicate that saturated fatty acids of varying chain length have differential effects on hepatic apoB/E receptor expression and on LDL apoB flux rates which in part account for differences in plasma LDL cholesterol levels of guinea pigs fed these saturated fats.     

Role of lamellar inclusions in surfactant production: studies on phospholipid composition and biosynthesis in rat and rabbit lung subcellular fractions.

Lamellar inclusion bodies in the type II alveolar epithelial cell are believed to be involved in pulmonary surfactant production. However, it is not clear whether their role is that of synthesis, storage, or secretion. We have examined the phospholipid composition and fatty acid content of rabbit lung wash, lamellar bodies, mitochondria, and microsomes. Phosphatidylcholine and phosphatidylglycerol, the surface-active components of pulmonary surfactant, accounted for over 80% of the total phospholipid in lung wash and lamellar bodies but for only about 50% in mitochondria and microsomes. Phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and sphingomyelin accounted for over 40% of the total in mitochondria and microsomes but for only 6% in lung wash and 15% in lamellar bodies. The fatty acid composition of lamellar body phosphatidylcholine was similar to that of lung wash, but different from that of mitochondria and microsomes, in containing palmitic acid as a major component with little stearic acid and few fatty acids of chain length greater than 18 carbon atoms. The biosynthesis of phosphatidylcholine and phosphatidylglycerol was examined in the mitochondrial, microsomal, and lamellar body fractions from rat lung. Cholinephosphotransferase was largely microsomal. The activity in the lamellar body fraction could be attributed to microsomal contamination. The activity of glycerolphosphate phosphatidyltransferase, however, was high in the lamellar body fraction, although it was highest in the mitochondria and was also active in the microsomes. These data suggest that the lamellar bodies are involved both in the storage of the lipid components of surfactant and in the synthesis of at least one of those components, phosphatidylglycerol.     

Cytokine profile and proteome analysis in bronchoalveolar lavage of patients with sarcoidosis, pulmonary fibrosis associated with systemic sclerosis and idiopathic pulmonary fibrosis

The aim of this study was to analyze the type of immune response (Th1, Th2) and protein composition of bronchoalveolar lavage (BAL) of patients with sarcoidosis, pulmonary fibrosis associated with systemic sclerosis (SSc) and idiopathic pulmonary fibrosis (IPF). Flow cytometry analysis of intracellular cytokines revealed different patterns: in IPF and SSc Th2 profiles were predominant, whereas in sarcoidosis Th1 prevailed. The proteomic analysis of BAL fluid (BALF) showed that there were quantitative differences between the three diseases. These were more evident between sarcoidosis and IPF, confirming our previous observations, whereas SSc had an intermediate profile between the two, however with some peculiarities. Comparison of BALF protein maps, constructed with the same quantity of total proteins, enabled us to identify the main profiles of the three diseases: an increase in plasma protein prevalent in sarcoidosis and also present in SSc, though for fewer proteins with respect to IPF and a greater abundance of low molecular weight proteins, mainly locally produced, in IPF. These findings are in line with the different pathogenesis of these diseases: IPF is considered a prevalently fibrotic disorder limited to the lung, with intense local production of functionally different proteins, whereas sarcoidosis and SSc are systemic immunoinflammatory diseases.     

The in vivo labeling with acetate and palmitate of lung phospholipids from developing and adult rabbits

The labeling with radiolabeled acetate and palmitate of lung, microsomes isolated from lung, and surfactant phospholipids from adult, 3-day-old, and newborn rabbits was studied. The half-life of phosphatidylcholine from lung and microsomal fractions was shorter when labeled with acetate than when labeled with palmitate. Half-time values similarly measured for phosphatidylglycerol, phosphatidylinositol or phosphatidylethanolamine were not different for the two labels. Acetate and palmitate-labeled phospholipids appeared in the surfactant fraction with similar accumulation curves. The relative specific activities of acetate-labeled phosphatidylcholine from adult, 3-day-old, and newborn rabbits, respectively, were 1.30, 1.86 and 1.77 times those measured for those measured for the palmitate label. Surfactant phosphatidylinositol and phosphatidylethanolamine from 3-day-old animals similarly were labeled preferentially with acetate. However, phosphatidylglycerol purified from the surfactant fraction contained equivalent relative amounts of the acetate and palmitate labels in 3-day-old and adult rabbits. These results suggest that the type II pneumocyte may use acetate preferentially for the synthesis of palmitic acid which then is incorporated into surfactant phospholipids.     

Fibrocytes are a potential source of lung fibroblasts in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis is characterized by the accumulation of fibroblasts/myofibroblasts and aberrant remodeling of the lung parenchyma. However, the sources of fibroblasts in IPF lungs are unclear. Fibrocytes are circulating progenitors of fibroblasts implicated in wound healing and fibrosis. In this study we evaluated evidence for the presence of fibrocytes in the lung of patients with idiopathic pulmonary fibrosis by immunofluorescence and confocal microscopy. Fibrocytes were identified in tissues in 8 out of 9 fibrotic lungs. Combinations including CXCR4 and a mesenchymal marker stained significantly more fibrocytes/mm(2) of tissue compared with combinations using CD34 or CD45RO with mesenchymal markers: CXCR4/procollagen-I (10.3+/-2.9fibrocytes/mm(2)) and CXCR4/prolyl-4-hydroxylase (4.1+/-3.1), versus CD34/procollagen-I (2.8+/-3.0), CD34/alphaSMA (2.2+/-1.6) and CD45RO/prolyl-4-hydroxylase (1.3+/-1.6); p<0.003. There was a positive correlation between the abundance of fibroblastic foci and the amount of lung fibrocytes (r=0.79; p<0.02). No fibrocytes were identified in normal lungs. The fibrocyte attractant chemokine CXCL12 increased in plasma [median: 2707.5pg/ml (648.1-4884.7) versus 1751.5pg/ml (192.9-2686.0) from healthy controls; p<0.003)] and was detectable in the bronchoalveolar lavage fluid of 40% of the patients but not in controls. In the lung CXCL12 was strongly expressed by alveolar epithelial cells. A negative correlation between plasma levels of CXCL12 with lung diffusing capacity for carbon monoxide (DLCO) (r=-0.56; p<0.03) and oxygen saturation on exercise was found (r=-0.41; p<0.04). These findings indicate that circulating fibrocytes, likely recruited through the CXCR4/CXCL12 axis, may contribute to the expansion of the fibroblast/myofibroblast population in idiopathic pulmonary fibrosis.     

Myristic acid, unlike palmitic acid, is rapidly metabolized in cultured rat hepatocytes

This study was designed to examine and compare the metabolism of myristic and palmitic acids in cultured rat hepatocytes. [1-(14)C]-Labeled fatty acids were solubilized with albumin at 0.1 mmol/L in culture medium. Incubation with 24-hr cultured hepatocytes was carried out for 12 hr. Myristic acid was more rapidly (P < 0.05) taken up by the cells than was palmitic acid (86.9 +/- 0.9% and 68.3 +/- 5.7%, respectively, of the initial radioactivity was cleared from the medium after 4 hr incubation). Incorporation into cellular lipids, however, was similar after the same time (33.4 +/- 2.8% and 34.9 +/- 9.3%, respectively, of initial radioactivity). In the early phase of the incubation (30 min), myristic acid was more rapidly incorporated into cellular triglycerides than was palmitic acid (7.4 +/- 0.9% and 3.6 +/- 1.9%, respectively, of initial radioactivity). However, after 12 hr incubation, the radioactivity of cellular triglycerides, cellular phospholipids, and secreted triglycerides was significantly higher with palmitic acid as precursor. Myristic acid oxidation was significantly higher than that of palmitic acid (14.9 +/- 2.2% and 2.3 +/- 0.6%, respectively, of the initial radioactivity was incorporated into the beta-oxidation products after 4 hr). Myristic acid was also more strongly elongated to radiolabeled palmitic acid (12.2 +/- 0.8% of initial radioactivity after 12 hr) than palmitic acid was to stearic acid (5.1 +/- 1.3% of initial radioactivity after 12 hr). The combination of elongation and beta-oxidation results in the rapid disappearance of C14:0 in hepatocytes whereas C16:0 is esterified to form glycerolipids. This study provides evidence that myristic acid is more rapidly metabolized in cultured hepatocytes than is palmitic acid.