Secretory Phospholipase A2 Digital Expression Analysis in Colon Adenocarcinoma

BACKGROUND/AIM

Phospholipases A2 represent a family of enzymes that regulate the metabolism of phospholipids by hydrolyzing them into fatty acids. Secretory phospholipase A2 (SPLA2) catalyzes the calcium-dependent 2-acyl groups hydrolysis to produce 3-sn-phosphoglycerides. This study aimed to investigate SPLA2 expression in colon adenocarcinoma (CA).

MATERIALS AND METHODS

Thirty (n=30) formalin-fixed, paraffin-embedded primary CA tissue sections were used and analyzed. Immunohistochemistry was performed using an anti-SPLA2 antibody. Digital image analysis was also implemented for evaluating objectively the corresponding protein expression levels.

RESULTS

Increased SPLA2 protein expression (high & moderate immunostaining levels) was observed in 23/30 (76.6%) cases, whereas 7/30 (23.4%) CA tissues demonstrated low protein levels. High expression levels were detected in 9/30 (30%) cases. SPLA2 overall expression was strongly associated with tumor diameter (p=0.004), whereas other statistically significant associations were not observed (stage: p=0.971, inflammatory infiltration: p=0.795; carcinoma location: p=0.340; differentiation grade: p=0.748; sex: p=0.369; ulceration: p=0.433).

CONCLUSION

SPLA2 over-expression is observed in significant subsets of CAs correlating with advanced tumor growth progression (increased diameter). SPLA2 seems to influence endogenous cell responses by its crucial enzymatic activity and can potentially be a biomarker for monitoring CA patients.

Impact of peroxiredoxin-6 expression on colon adenocarcinoma

PURPOSE

Peroxiredoxins (Prdxs) represent a family of proteins that act as antioxidant enzymes and are involved in a variety of metabolic functions including mainly the intracellular hydrogen peroxide (H2O2) levels reduction. Especially, Prdx-6 protein encoded by the PRDX6 gene (1q25.1) regulates also phospholipid modifications and induces response to oxidative stress and injuries. Our aim was to investigate the expression of Prdx-6 in colon adenocarcinoma (CA).

METHODS

A series of 30 formalin-fixed, paraffin-embedded primary CAs tissue sections were used and analyzed. Immunohistochemistry was performed using an anti-Prdx-6 antibody. Digital image analysis was also implemented for evaluating objectively the protein expression levels on the corresponding stained cells.

RESULTS

Prdx-6 protein overexpression (increased immunostaining levels) was observed in 12/30 (40%) cases, whereas 18/30 (60%) CA tissues demonstrated low to moderate protein levels, respectively. Prdx-6 overall expression was strongly associated with the stage of the examined tumors (p=0.011), whereas other statistical significances were not assessed (inflammatory infiltration: p=0.364; carcinoma location: p=0.93; differentiation grade: p=0.517; tumor diameter: p=0.983; ulceration: p=0.622).

CONCLUSIONS

Prdx-6 overexpression is observed in a significant subset of CAs correlating with aggressive biological behavior (advanced stage). Prdx-6 is a crucial enzyme for oxidative stress/injury endogenous cell response and should be an interesting agent as a biomarker and potential therapeutic target.

Phospholipases A2 as biomarkers in ARDS

Acute respiratory distress syndrome (ARDS) is a multifactorial life-threatening lung injury, characterized by diffuse lung inflammation and increased alveolocapillary barrier permeability. The different stages of ARDS have distinctive biochemical and clinical profiles. Despite the progress of our understanding on ARDS pathobiology, the mechanisms underlying its pathogenesis are still obscure. Herein, we review the existing literature about the implications of phospholipases 2 (PLA2s), a large family of enzymes that catalyze the hydrolysis of fatty acids at the sn-2 position of glycerophospholipids, in ARDS-related pathology. We emphasize on the versatile way of participation of different PLA2s isoforms in the distinct ARDS subgroup phenotypes by either potentiating lung inflammation and damage or by preserving the normal lung. Current research supports that PLA2s are associated with the progression and the outcome of ARDS. We herein discuss the transcellular communication of PLA2s through secreted extracellular vesicles and suggest it as a new mechanism of PLA2s involvement in ARDS. Thus, the elucidation of the spatiotemporal features of PLA2s expression may give new insights and provide valuable information about the risk of an individual to develop ARDS or advance to more severe stages, and potentially identify PLA2 isoforms as biomarkers and target for pharmacological intervention.

Docosahexaenoic Acid Inhibits Proliferation of EoL-1 Leukemia Cells and Induces Cell Cycle Arrest and Cell Differentiation

Τhe effect of docosahexaenoic acid (DHA, an omega-3 polyunsaturated fatty acid) upon the proliferation of EoL-1 (Eosinophilic leukemia) cell line was assessed, while additional cellular events during the antiproliferative action were recorded. DHA inhibited EoL-1 cells growth dose-dependently by inducing growth arrest at G0/1 phase of the cell cycle. After DHA addition to the cells, the expression of MYC oncogene was decreased, PTAFR-mRNA overexpression was observed which was used as a marker of differentiation, and PLA2G4A-mRNA increase was recorded. The enzymatic activities of phospholipase A₂ (PLA₂), a group of hydrolytic enzymes, whose action precedes and leads to PAF biosynthesis through the remodeling pathway, as well as platelet activating factor acetylhydrolase (PAFAH) which hydrolyses and deactivates PAF, were also measured. DHA had an effect on the levels of both the intracellular and secreted activities of PLA₂ and PAFAH. The inflammatory cytokines IL-6 and TNF-α were also detected in high levels. In conclusion, DHA-induced EoL-1 cells differentiation was correlated with downregulation of MYC oncogene, overexpression of PTAFR and PLA2G4A-mRNAs, increase of the inflammatory cytokines production, and alteration of the enzymatic activities that regulate PAF levels. DHA is a natural substance and the understanding of its action on EoL-1 cells on molecular level could be useful in further investigation as a future therapeutic tool against F/P ⁺ hypereosinophilic syndrome.

Effect of azithromycin on the LPS-induced production and secretion of phospholipase A2 in lung cells

Azithromycin is a member of macrolides, utilized in the treatment of infections. Independently, these antibiotics also possess anti-inflammatory and immunomodulatory properties. Phospholipase A2 isotypes, which are implicated in the pathophysiology of inflammatory lung disorders, are produced by alveolar macrophages and other lung cells during inflammatory response and can promote lung injury by destructing lung surfactant. The aim of the study was to investigate whether in lung cells azithromycin can inhibit secretory and cytosolic phospholipases A2, (sPLA2) and (cPLA2), respectively, which are induced by an inflammatory trigger. In this respect, we studied the lipopolysaccharide (LPS)-mediated production or secretion of sPLA2 and cPLA2 from A549 cells, a cancer bronchial epithelial cell line, and alveolar macrophages, isolated from bronchoalveolar lavage fluid of ARDS and control patients without cardiopulmonary disease or sepsis. Pre-treatment of cells with azithromycin caused a dose-dependent decrease in the LPS-induced sPLA2-IIA levels in A549 cells. This inhibition was rather due to reduced PLA2G2A mRNA expression and secretion of sPLA2-IIA protein levels, as observed by western blotting and indirect immunofluorescence by confocal microscopy, respectively, than to the inhibition of the enzymic activity per se. On the contrary, azithromycin had no effect on the LPS-induced production or secretion of sPLA2-IIA from alveolar macrophages. The levels of LPS-induced c-PLA2 were not significantly affected by azithromycin in either cell type. We conclude that azithromycin exerts anti-inflammatory properties on lung epithelial cells through the inhibition of both the expression and secretion of LPS-induced sPLA2-IIA, while it does not affect alveolar macrophages.

Influence of propofol and volatile anaesthetics on the inflammatory response in the ventilated lung

BACKGROUND

The immunomodulatory effects of volatile anaesthetics in vitro and the protective effect of propofol in lung injury spurred us to study the effects of volatile anaesthetics and propofol on lung tissue in vivo.

METHODS

Twenty-seven pigs were randomized to 4-h general anaesthesia with propofol (8 mg/kg/h, group P, n=9), sevoflurane [minimum alveolar concentration (MAC)=1.0, group S, n=9) or desflurane (MAC=1.0, group D, n=9). Four healthy animals served as the no-ventilation group. Bronchoalveolar lavage fluid (BALF) was obtained to measure the cell counts, platelet-activating factor acetylhydrolase (PAF-AcH), phospholipase A(2) (PLA(2)) and superoxide dismutase (SOD) activity. Lung tissues were evaluated histologically and for caspase-3 expression.

RESULTS

Volatile anaesthetics reduced PAF-AcH levels without affecting PLA(2) activity and resulted in decreased alveolar macrophage and increased lymphocyte counts in BALF (sevoflurane: 29 ± 23%; desflurane: 26 ± 6%, both P<0.05 compared with 4 ± 2% in the no-ventilation group). These findings were accompanied by atelectasis and inflammatory cells' infiltration in the inhalational anaesthetics groups. Also, sevoflurane reduced SOD activity and both sevoflurane and desflurane induced significant caspase-3 expression. In contrast, propofol resulted in a minor degree of inflammation and preserved BALF cells' composition without triggering apoptosis.

CONCLUSION

Halogenated anaesthetics seem to trigger an immune lymphocytic response in the lung, inducing significant apoptosis and impairment of PAF-AcH. In contrast, propofol preserves anti-inflammatory and anti-oxidant defences during mechanical ventilation, thus preventing the emergence of apoptosis.

Phospholipase A2 subclasses in acute respiratory distress syndrome

Phospholipases A2 (PLA2) catalyse the cleavage of fatty acids esterified at the sn-2 position of glycerophospholipids. In acute lung injury-acute respiratory distress syndrome (ALI-ARDS) several distinct isoenzymes appear in lung cells and fluid. Some are capable to trigger molecular events leading to enhanced inflammation and lung damage and others have a role in lung surfactant recycling preserving lung function: Secreted forms (groups sPLA2-IIA, -V, -X) can directly hydrolyze surfactant phospholipids. Cytosolic PLA2 (cPLA2-IVA) requiring Ca2+ has a preference for arachidonate, the precursor of eicosanoids which participate in the inflammatory response in the lung. Ca(2+)-independent intracellular PLA2s (iPLA2) take part in surfactant phospholipids turnover within alveolar cells. Acidic Ca(2+)-independent PLA2 (aiPLA2), of lysosomal origin, has additionally antioxidant properties, (peroxiredoxin VI activity), and participates in the formation of dipalmitoyl-phosphatidylcholine in lung surfactant. PAF-AH degrades PAF, a potent mediator of inflammation, and oxidatively fragmented phospholipids but also leads to toxic metabolites. Therefore, the regulation of PLA2 isoforms could be a valuable approach for ARDS treatment.

Phospholipases A2 and platelet-activating-factor acetylhydrolase in patients with acute respiratory distress syndrome*

OBJECTIVE

Phospholipases A2 (PLA2) comprise a family of enzymes probably implicated in the development of acute respiratory distress syndrome (ARDS). The aim was to investigate PLA2 activities and characteristics in bronchoalveolar lavage (BAL) fluid, BAL cells, and plasma from patients with ARDS by a fluorometric method.

DESIGN

Prospective, controlled study.

SETTING

Fourteen-bed polyvalent intensive care unit in a university hospital.

PATIENTS

A total of 31 mechanically ventilated patients, 20 with and 11 without ARDS, were studied.

INTERVENTION

BAL was performed by fiberoptic bronchoscopy in mechanically ventilated patients with a controlled mechanical ventilation mode.

MEASUREMENTS

PLA2 and platelet-activating-factor acetylhydrolase were determined in BAL fluid, cells, and plasma. For the classification of PLA2-specific inhibitors, Western blot analysis and their biochemical characteristics were used.

RESULTS

In ARDS patients, increased PLA2 levels were detected in BAL fluid, BAL cells, and plasma compared with the control patients. PLA2 in BAL fluid was mainly type IIA secretory and cytosolic types. In plasma, type IIA secretory and cytosolic and a Ca-independent PLA2 were found. In BAL cells, a cytosolic form, probably a Ca-independent intracellular form, and a low activity of type IIA secretory PLA2 was also observed. Total PLA2 activity correlated inversely with Pao2/Fio2 ratio and positively with the mortality rate. Patients with direct ARDS exhibited higher PLA2 activity compared with patients with indirect ARDS. Platelet-activating-factor acetylhydrolase activity was higher in BAL fluid and plasma, but it was lower in BAL cells.

CONCLUSION

Ca-dependent, secretory, cytosolic, and Ca-independent forms of PLA2 and platelet-activating-factor acetylhydrolase could play important roles in the development or down-regulation of inflammation in ARDS, respectively.

Alterations in bronchoalveolar lavage fluid during ischemia-induced acute hepatic failure in the pig

The objective of this controlled experimental animal study was to evaluate whether acute hepatic failure (AHF) can cause acute lung injury (ALI) and to investigate possible pathophysiologic mechanisms. Seventeen domestic pigs were randomly assigned to AHF and sham groups. AHF was induced by surgical devascularization of liver in 10 animals. Seven animals were sham operated. Hemodynamics, lung mechanics, extravascular lung water (EVLW), and intracranial pressure, blood gas, liver function tests, and serum endotoxin levels were measured. Cells count, total protein, and phospholipids and phospholipases A(2) were determined in the bronchoalveolar lavage (BAL) fluid. Measurements were obtained after the insertion of central lines and 4 hours and 7 hours after the completion of the surgical procedure. Hemodynamic, biochemical, neuromonitoring, and histologic data confirmed the development of liver failure. Seven hours after devascularization, EVLW was higher in AHF (13.7 +/- 1.8 mL/kg) compared with the sham group (5.9 +/- 0.7 mL/kg) (P <.05); in AHF, increase of neutrophils (5% +/- 8% to 25% +/- 8%, P <.001), total protein (6.2 +/- 3.7 to 11.2 +/- 6.5 microg/mL, P <.048), and phospholipase A(2) (1.43 +/- 0.56 to 2.38 +/- 1.38 nmoL/mL/h, P <.03) and decrease in PAF-acetylhydrolase (0.114 +/- 0.128 to 0.039 +/- 0.038 nmol/mL/h, P <.01) compared with baseline were observed; total phospholipids decreased in AHF and increased in the sham model. Histologic examination confirmed lesions compatible with acute lung injury. In conclusion, AHF due to hepatic devascularization induced acute lung injury, confirmed by the increase of inflammatory cells in the alveoli as well as by histologic findings. The decreased PAF-AcH and the increased phospholipase A(2) may play a significant role in the perpetuation of inflammation accompanied by surfactant disorders.

Ventilator-associated pneumonia and atelectasis: evaluation through bronchoalveolar lavage fluid analysis

OBJECTIVE

Surfactant offers protection against alveolar collapse and contributes to the local defense mechanism, but it is unclear if surfactant alterations have a role in the development of atelectasis or ventilator-associated pneumonia (VAP). The present study was undertaken to monitor surfactant, as well as biochemical BAL fluid alterations, during the course of VAP and atelectasis in mechanically ventilated patients without primary cardiopulmonary disease, to elucidate the pathogenesis and to differentiate these two entities. DESIGN. Prospective controlled study.

SETTING

14-bed general ICU of a 750-bed University Hospital.

PATIENTS

Sixty-one ventilated patients, without primary cardiopulmonary disease-normal initial chest X-ray, satisfactory oxygenation (PaO(2)/FiO(2)>300 mmHg), and expected time of ventilation exceeding 2 weeks-were initially enrolled. Twelve of them developed VAP and eight lobar or segmental atelectasis during the 2-week study period.

INTERVENTIONS

An initial BAL was performed in all patients within 48 h from admission. Patients who developed VAP or atelectasis were subjected to a second and third BAL during and after the resolution of VAP or atelectasis, respectively.

MEASUREMENTS AND RESULTS

VAP and atelectasis resulted in a significant increase of total protein and markers of inflammation, such as PAF and neutrophils, which partially remitted after their resolution. Large surfactant aggregates, which contribute to surface tension decrease, were significantly reduced during both entities and remained low even after their resolution.

CONCLUSIONS

BAL alterations during VAP and atelectasis suggest increased alveolar-capillary permeability, severe surfactant abnormalities, and signs of local inflammatory reaction. These alterations are associated with the observed deteriorated gas exchange and lung mechanics and could predispose to further lung injury in ventilated patients.

Bronchoalveolar lavage alterations during prolonged ventilation of patients without acute lung injury

Mechanical ventilation deteriorates previously injured lung, but little is known about its effect on healthy human lung. This work was designed to assess the effect of prolonged mechanical ventilation on bronchoalveolar lavage (BAL) fluid composition of patients without acute lung injury. Twenty-two ventilated patients (tidal volume 8-10 mL x kg(-1), positive end-expiratory pressure 3-5 cmH2O) without lung injury, who did not develop any complication from the respiratory system during the 2-week study period, were studied. They were subjected to three consecutive BALs, the first during 36 h from intubation, the second at the end of the first week of mechanical ventilation and the third at the end of the second week of mechanical ventilation. Total BAL protein increased during mechanical ventilation (148 +/- 62, 381 +/- 288, 353 +/- 215 microg x mL(-1) BAL for the first, second and third BAL, respectively). In contrast, BAL phospholipids decreased (2.7 +/- 1.1, 1.4 +/- 0.6, 1.2 +/- 0.7 microg x mL(-1) BAL, respectively). Large surfactant aggregates were reduced and inflammatory markers, such as platelet activating factor (PAF), PAF-acetylhydrolase and neutrophils, significantly increased after 1 week, but partially remitted after 2 weeks of mechanical ventilation. In summary, this study demonstrates that prolonged mechanical ventilation even of patients without acute lung injury is associated with the presence of inflammatory markers and surfactant alterations.

Lipids are co-eluted with immunoglobulins G during purification by recombinant streptococcal protein G affinity chromatography

The efficiency of recombinant streptococcal protein G (rec-spG) affinity column chromatography in purifying immunoglobulins G (IgG) from lipids has been studied, with particular reference to IgG fractions from bronchoalveolar lavage (BAL) fluid and serum samples from different sources. It was found that the IgG fractions purified by rec-spG affinity column chromatography also contained cholesterol and phospholipids.

Immunoparalysis in patients with severe trauma and the effect of inhaled interferon-gamma

OBJECTIVE

To evaluate the local immune status in patients with severe trauma and the influence of interferon-gamma on patients with immunoparalysis.

PATIENTS

Fifty-two mechanically ventilated patients with severe multiple trauma.

SETTING

A 14-bed polyvalent intensive care unit.

INTERVENTIONS

The local immune status was evaluated by examining bronchoalveolar lavage fluid. Subsequently, the patients were divided into two groups: immunoparalyzed (group 1) and nonimmunoparalyzed (group 2). Immunoparalysis was defined as a decreased level of human leukocyte antigen-DR expression of alveolar macrophages in <30%. Patients with immunoparalysis were treated with 100 microg of inhaled recombinant human interferon-gamma, three times daily (group 1a, 11 patients) or placebo (group 1b, ten patients). A second bronchoalveolar lavage fluid was obtained 3 days after the initiation of therapy.

MEASUREMENTS

The alterations in human leukocyte antigen-DR expression, as well as in pro- and anti-inflammatory markers, such as platelet-aggregating factor, phospholipase A2, interleukin-1beta, platelet-aggregating factor acetylhydrolase, and interleukin-10, were evaluated in the bronchoalveolar lavage fluids.

RESULTS

In 21 of 52 (40%) patients, immunoparalysis was established. After interferon-gamma administration, the level of human leukocyte antigen-DR expression increased in group 1a from 17 +/- 5% to 46 +/- 9%. In parallel, platelet-aggregating factor and interleukin-1beta as well as the specific activities of phospholipase A2 and platelet-aggregating factor acetylhydrolase significantly increased. In contrast, interleukin-10 decreased after interferon-gamma therapy. In group 1b, no statistically significant changes appeared in the levels of human leukocyte antigen-DR expression or in the concentrations of inflammatory mediators. The incidence of ventilator-associated pneumonia was significantly lower in group 1a than in group 1b. The administration of interferon-gamma did not affect the outcome of the patients.

CONCLUSIONS

A significant proportion of multiply injured patients developed immunoparalysis. The administration of interferon-gamma resulted in the recovery of levels of human leukocyte antigen-DR expression in alveolar macrophages, influenced the inflammatory reaction, and decreased the incidence ventilator-associated pneumonia, without affecting the patients' outcome.

Autoantibodies to lipids in bronchoalveolar lavage fluid of patients with acute respiratory distress syndrome

OBJECTIVE

To investigate the presence of autoantibodies to lipids in the bronchoalveolar lavage (BAL) fluid from adult patients with acute respiratory distress syndrome (ARDS).

DESIGN

Analysis of immunoglobulin G (IgG) in BAL fluid by electrophoresis followed by immunoblotting and characterization of immunoglobulins as antilipid autoantibodies.

SETTING

Intensive care unit of a university hospital and two research university laboratories.

SUBJECTS

Twenty-seven mechanically ventilated patients in total, including nine patients with ARDS and two control groups.

INTERVENTIONS

Patients were ventilated with a mechanical ventilation mode. Six aliquots of 20-mL sterile normal saline at 37 degrees C were infused through the working channel of the bronchoscope.

MEASUREMENTS

Total protein, detection of IgG by electrophoresis followed by immunoblotting, and characterization of IgG by enzyme-linked immunosorbent assay using different lipids as target antigens.

MAIN RESULTS

Antiphospholipid autoantibodies are present in BAL fluid of ARDS patients. Among the phospholipids tested, phosphatidic acid and phosphatidylserine gave the most significant activity. The IgG fraction, purified from BAL fluids by affinity chromatography, gave the same pattern of binding as that of the BAL fluid.

CONCLUSION

The presence of antiphospholipid autoantibodies in BAL fluid suggests involvement of autoimmune mechanisms in the pathogenesis of ARDS.

The characteristics of bronchoalveolar lavage from a patient with antiphospholipid syndrome who developed acute respiratory distress syndrome

The purpose of this study was to investigate the biochemical characteristics as well as the occurrence and specificity of antiphospholipid antibodies in the bronchoalveolar lavage (BAL) fluid from a patient with both antiphospholipid antibodies syndrome (APS) and acute respiratory distress syndrome (ARDS). Proteins, lipids, cells and autoantibodies were determined. Immunoglobulins were purified with affinity chromatography. Autoantibody identification was assessed with enzyme-linked immunosorbent assay (ELISA) and with electrophoresis, followed by immunoblotting and revelation with antihuman IgG-peroxidase conjugate. Antiphospholipid antibodies were found to be present in the BAL fluid as well as in the serum from a patient with APS. Specifically, antiphosphatidylserine and antiphosphatidic acid IgG antibodies in the BAL fluid and antiphosphatidylcholine and anticardiolipin IgG antibodies in the serum were detected at high levels. BAL fluid protein and the percentage of neutrophils were found to be increased. A quantitative as well as qualitative deficiency of surfactant phospholipids was also observed. Antibodies directed against surfactant phospholipids could cause surfactant abnormalities and an inflammatory reaction. These disorders may be one of the causes of the ARDS or a factor in the perpetuation of the inflammation.