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Biomedical subjects

J A Lindgren

Publications and source records attributed to J A Lindgren.

At least 19 recordsLinked to original sources
PubMed2002

Uncoupled regulation of leukotriene C4 synthase in platelets from aspirin-intolerant asthmatics and healthy volunteers after aspirin treatment.

BACKGROUND: We have reported that thromboxane A2 induces suppression of leukotriene (LT) C4 synthase activity in human platelets. AIM: In the present study, we describe a mechanism whereby aspirin treatment can lead to increased formation of LTC4, which is a potent bronchoconstrictor and inflammatory mediator. This mechanism is also demonstrated to be present in platelets from aspirin-intolerant asthmatics (AIA). METHODS: The effect of arachidonic acid or platelet agonists on LTC4 synthase activity was investigated in platelets obtained from healthy volunteers, aspirin-intolerant asthmatics or aspirin-tolerant asthmatics after in vivo treatment or in vitro pre-incubation with aspirin. RESULTS: Incubation of normal platelets with arachidonic acid or collagen provoked approximately 50% reduction of platelet LTC4 synthase activity, as determined by the conversion of LTA4 to LTC4. However, the inhibitory effect of arachidonic acid or collagen was not observed after oral administration of aspirin prior to collection of the platelets. Arachidonic acid-induced inhibition of LTC4 synthase activity was totally abolished in platelets collected from peripheral blood already 30 min after aspirin ingestion but was fully restored in platelets collected 3 to 7 days after the administration of aspirin. Treatment of platelet suspensions with aspirin in vitro dose-dependently counteracted the suppressive effect of arachidonic acid on LTC4 formation, with total reversal at approximately 40 microm. In contrast, the major aspirin metabolite, salicylic acid did not alter arachidonic acid-induced reduction of LTC4 synthase activity. Similarly, LTC4 synthase activity in platelets from AIA and aspirin-tolerant asthmatics (ATA) was reduced by approximately 50% after pre-treatment with arachidonic acid in vitro. Again the inhibitory effect was abolished when platelets were pre-incubated in the presence of aspirin. CONCLUSION: The results indicate that oral aspirin administration can lead to uncoupling of thromboxane A2-dependent negative feedback mechanisms, which may normally restrict the production of cysteinyl leukotrienes. This mechanism can be of potential interest in aspirin-induced asthma.

Adult↗
PubMed2000

15-Lipoxygenation of leukotriene A(4). Studies Of 12- and 15-lipoxygenase efficiency to catalyze lipoxin formation.

The unstable epoxide leukotriene (LT) A(4) is a key intermediate in leukotriene biosynthesis, but may also be transformed to lipoxins via a second lipoxygenation at C-15. The capacity of various 12- and 15-lipoxygenases, including porcine leukocyte 12-lipoxygenase, a human recombinant platelet 12-lipoxygenase preparation, human platelet cytosolic fraction, rabbit reticulocyte 15-lipoxygenase, soybean 15-lipoxygenase and human eosinophil cytosolic fraction, to catalyze conversion of LTA(4) to lipoxins was investigated and standardized against the ability of the enzymes to transform arachidonic acid to 12- or 15-hydroxyeicosatetraenoic acids (HETE), respectively. The highest ratio between the capacity to produce lipoxins and HETE (LX/HETE ratio) was obtained for porcine leukocyte 12-lipoxygenase with an LX/HETE ratio of 0.3. In addition, the human platelet 100000xg supernatant 12-lipoxygenase preparation and the human platelet recombinant 12-lipoxygenase and human eosinophil 100000xg supernatant 15-lipoxygenase preparation possessed considerable capacity to produce lipoxins (ratio 0.07, 0.01 and 0.02 respectively). In contrast, lipoxin formation by the rabbit reticulocyte and soybean 15-lipoxygenases was much less pronounced (LX/HETE ratios <0.002). Kinetic studies of the human lipoxygenases revealed lower apparent K(m) for LTA(4) (9-27 microM), as compared to the other lipoxygenases tested (58-83 microM). The recombinant human 12-lipoxygenase demonstrated the lowest K(m) value for LTA(4) (9 microM) whereas the porcine leukocyte 12-lipoxygenase had the highest V(max). The profile of products was identical, irrespective of the lipoxygenase used. Thus, LXA(4) and 6S-LXA(4) together with the all-trans LXA(4) and LXB(4) isomers were isolated. Production of LXB(4) was not observed with any of the lipoxygenases. The lipoxygenase inhibitor cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate was considerably more efficient to inhibit conversion of LTA(4) to lipoxins, as compared to the inhibitory effect on 12-HETE formation from arachidonic acid (IC(50) 1 and 50 microM, respectively) in the human platelet cytosolic fraction.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed2000

Aberrant expression of active leukotriene C(4) synthase in CD16(+) neutrophils from patients with chronic myeloid leukemia.

Elevated leukotriene (LT)C(4) synthase activity was observed in peripheral blood granulocyte suspensions from patients with chronic myeloid leukemia (CML). Magnetic cell sorting (MACS) with CD16 monoclonal antibodies (mAbs), which were used to fractionate granulocytes from CML patients and healthy individuals, yielded highly purified suspensions of CD16(+) neutrophils. The purity of these cell fractions was verified by extensive morphologic examination. Reverse transcriptase-polymerase chain reaction (RT-PCR) analyses, demonstrating the absence of interleukin-4 messenger RNA (IL-4 mRNA), further confirmed the negligible contamination of eosinophils in these fractions. Notably, purified CML CD16(+) neutrophils from all tested patients transformed exogenous LTA(4) to LTC(4). These cells also produced LTC(4 )after activation with ionophore A23187 or the chemotactic peptide fMet-LeuPhe (N-formylmethionyl-leucyl-phenylalanine). Subcellular fractionation revealed that the enzyme activity was exclusively distributed to the microsomal fraction. Expression of LTC(4) synthase mRNA in CML CD16(+) neutrophils was confirmed by RT-PCR. Furthermore, Western blot analyses consistently demonstrated expression of LTC(4) synthase at the protein level in CML CD16(+) neutrophils, whereas expression of microsomal glutathione S-transferase 2 occurred occasionally. Expectedly, LTC(4) synthase activity or expression of the protein could not be demonstrated in CD16(+) neutrophil suspensions from any of the healthy individuals. Instead, these cells, as well as CML CD16(+) neutrophils, transformed LTA(4) to LTB(4). The results indicate that aberrant expression of LTC(4) synthase is a regular feature of morphologically mature CML CD16(+) neutrophils. This abnormality, possibly associated with malignant transformation, can lead to increased LTC(4) synthesis in vivo. Such overproduction may be of pathophysiological relevance because LTC(4 )has been demonstrated to stimulate proliferation of human bone marrow-derived myeloid progenitor cells. (Blood. 2000;95:1456-1464)

Antigens, CD↗
PubMed2000

Impaired leukotriene C4 generation in granulocytes from protein-energy malnourished chronically ill elderly.

OBJECTIVE: The dysregulation of the immune and inflammatory systems observed in protein-energy malnutrition (PEM) may be partly due to perturbation of essential fatty acid metabolism. In this study, we assessed the calcium ionophore A23187-induced generation of the arachidonate metabolites leukotriene B4 (LTB4) and leukotriene C4 (LTC4) in isolated granulocyte suspensions. DESIGN: Case-control study. SETTING: A university-affiliated acute care hospital in urban Stockholm. SUBJECTS: Fourteen severely malnourished elderly subjects with stable non-malignant disorders (age 74 +/- 1 years, mean +/- SEM) and 12 healthy age-matched controls were examined. MAIN OUTCOME MEASURES: Leukotrienes were analysed by high-performance liquid chromatography. Body mass index (BMI, kg m-2) and delayed cutaneous hypersensitivity (DCH) reaction were determined. RESULTS: BMI was 16. 5 +/- 0.5 and 26.2 +/- 0.9 kg m-2 (mean +/- SE) in the malnourished group and controls (P < 0.001), respectively. DCH was 8.5 mm (median) in patients and 29.5 mm in controls (P < 0.001). LTC4 generation in granulocytes from PEM patients was half of that of controls (9.1 +/- 2.0 vs. 17.8 +/- 5.2 pmol mL-1, P < 0.05) when cells were stimulated with 0.2 micromol L-1 of A23187, and 13.7 +/- 2.5 and 27.2 +/- 7.5 pmol mL-1, respectively (NS), upon stimulation with 1.0 micromol L-1 of A23187. LTB4 production in PEM patients and controls did not differ at any of the two calcium ionophore concentrations. LTC4 production correlated with BMI (r = 0.41, P < 0.05), but there was no significant correlation between DCH and LTB4 or LTC4 production. CONCLUSION: Protein-energy malnutrition is accompanied by perturbation of leukotriene synthesis, which may be one factor underlying the dysregulation of inflammatory responses in the depleted patient.

Aged↗
PubMed2000

Purification, characterization, and cDNA sequencing of cytosolic phospholipase A(2) from equine neutrophils.

It has been demonstrated that equine neutrophils, but not eosinophils, require exogenous arachidonic acid for calcium ionophore A23187-induced leukotriene synthesis. Because cytosolic phospholipase A(2) (cPLA(2)) plays an essential role in leukotriene formation in leukocytes, we investigated the presence of a functional cPLA(2) in equine neutrophils. To determine whether cPLA(2) from neutrophils was catalytically active, we purified the enzyme >6,500 fold with 3% recovery from equine neutrophils. The full-length cDNA sequence encoded a 749-amino acid protein. The deduced amino acid sequence demonstrated 95% identity with human and mouse cPLA(2), as well as 83 and 73% identity with chicken and zebra fish cPLA(2) protein, respectively. The equine cPLA(2) possessed some properties that distinguished the equine enzyme from the human enzyme. First, the enzyme activity of the equine cPLA(2) was differently influenced by cations as compared with the human cPLA(2). Second, the equine neutrophil cPLA(2) migrated as an approximately 105-kDa protein, in comparison with human cPLA(2) which migrated as a 110-kDa protein. A difference between equine neutrophils and eosinophils in the degree of phosphorylation of the cPLA(2) protein was observed. Thus, the cPLA(2) protein from eosinophils was constitutively phosphorylated, while the cPLA(2) protein from neutrophils was unphosphorylated. In summary, these results demonstrate that equine neutrophils indeed express an active cPLA(2) protein but that there is a difference in the degree of phosphorylation of the cPLA(2) protein between equine neutrophils and eosinophils. This difference might explain the difference between the two cell types in the capacity to produce leukotrienes from endogenous substrate.

Amino Acid Sequence↗
PubMed1999

The effects of an endurance ride on metabolism and neutrophil function.

The effects of an endurance ride on neutrophil functions in endurance-trained horses were evaluated and related to metabolic changes and changes in cortisol concentrations. Blood samples were taken from 7 horses (aged 9-15 years) one day before, and then 30-60 min, 1 day and 8 days after the ride. The race resulted in elevated serum cortisol levels (< 465 nmol/l) and an increased neutrophil:lymphocyte ratio. Immediately post race, the neutrophil ability to engulf yeast was increased. One day after the race, a decrease in leukotriene B4 production (approximately 40%) and in the respiratory burst (approximately 75%) was observed. Blood glucose concentration remained unchanged, as did serum lactate, which was low. After the race, the muscle glycogen stores were about 33% of the values noted after 8 days of recovery. Histochemical staining showed that 22 +/- 2% of the muscle fibres were totally depleted of glycogen. CK activity increased significantly from 40 +/- 10 mmol/min pre-race to 228 +/- 38 mmol/min post race. It was concluded that both hormonal and metabolic changes occurred during an endurance ride, which not only triggered neutrophil activation, but also induced alterations in their functional capacities.

Animals↗
PubMed1998

Effects of 1-chloro-2,4,6-trinitrobenzene on 5-lipoxygenase activity and cellular leukotriene synthesis.

5-Lipoxygenase (EC 1.13.11.34) is the key enzyme in the regulation of leukotriene synthesis. Here, the effects of various substituted nitrobenzene compounds on 5-lipoxygenase activity and the formation of leukotriene B4 (LTB4) were studied in polymorphonuclear leukocytes (PMNL), B lymphocytes, and human whole blood. 1-Chloro-2,4,6-trinitrobenzene (TNCB) was found to inhibit calcium ionophore A23187-induced leukotriene synthesis in PMNL in a biphasic manner. Thus, 1.0 microM TNCB caused 50% inhibition of LTB4 formation, but only 16% inhibition was found at 10 times higher concentration. In contrast, this higher concentration of TNCB activated the synthesis of LTB4 when PMNL were stimulated with arachidonic acid alone, demonstrating that TNCB can exert both stimulatory and inhibitory effects on leukotriene synthesis depending on the experimental conditions. The inhibitory effect of 1.0 microM TNCB on ionophore A23187-induced leukotriene synthesis could be circumvented by addition of exogenous arachidonic acid. At high concentrations of TNCB (25-100 microM), the drug blocked ionophore A23187-induced leukotriene synthesis. TNCB also inhibited LTB4 formation in B lymphocytes, as well as in human whole blood. The activity of recombinant 5-lipoxygenase was inhibited by TNCB, and reduced glutathione or beta-mercaptoethanol counteracted this inhibition. This suggests that TNCB might inhibit 5-lipoxygenase by alkylating thiol groups. TNCB possessed a high specificity for 5-lipoxygenase with only modest inhibitory effects on 12-lipoxygenase (EC 1.13.11.31), 15-lipoxygenase (EC 1.13.11.12), and phospholipase A2 (EC 3.1.1.4) activities. Taken together, these results show that TNCB can both specifically inhibit and stimulate leukotriene formation and might be useful in further studies on the regulation of 5-lipoxygenase.

Arachidonate 12-Lipoxygenase↗
PubMed1998

Demonstration of leukotriene-C4 synthase in platelets and species distribution of the enzyme activity.

Human platelets have been demonstrated to possess leukotriene (LT)-C4 synthase activity and may thus be involved in transcellular 5(S)-hydroxy-6(R)-S-glutathionyl-7,9-trans-11,14-cis-eicosatetraenoic acid (LTC4) synthesis. In this study, platelets from seven different species were screened for LTC4 synthase activity. Very high enzyme activity was observed in suspensions of bovine platelets, with approximately 70% conversion of 5(S)-trans-5,6-oxido-7,9-trans-11,14-cis-eicosatetraenoic acid (LTA4) to LTC4. The capacity of equine platelets to produce LTC4 was similar to that of human platelets. In addition, ovine, rabbit, and rat platelets also produced LTC4 after incubation with LTA4. The results demonstrate that LTC4 synthase activity is a common feature among platelets from various species. In contrast, porcine platelets failed to transform LTA4 to LTC4. Instead, these cells produced 5(S),12(R)-dihydroxy-6,14-cis-8,10-trans-eicosatetraenoic acid (LTB4), indicating the presence of LTA4 hydrolase in porcine platelets. A protein with a molecular mass of approximately 18 kDa and LTC4 synthase activity was solubilised from lyophilised bovine platelet concentrates and purified to near homogeneity by affinity chromatography and gel filtration. The N-terminal amino acid sequence of this protein was analysed and found to be almost identical to the corresponding sequence of human LTC4 synthase (17 of 18 amino acid residues identical). Kinetic analysis of partially purified bovine platelet LTC4 synthase revealed Km (for LTA4) and Vmax values of 3.3 microM and 521 nmol x mg protein(-1) x min(-1), respectively. In addition, the presence of a mRNA transcript encoding LTC4 synthase was demonstrated in equine platelets by reverse transcription (RT) PCR using primers derived from the human LTC4 synthase cDNA sequence. Cloning and sequencing of the PCR fragment corresponding to a region near the N-terminus demonstrated very high identity between equine and human leukotriene-C4 synthase in this region. In summary, the present study establishes that platelets contain LTC4 synthase and indicates that this enzyme is widely distributed among platelets from various species.

Amino Acid Sequence↗
PubMed1998

Expression of mRNA encoding neurotrophins and neurotrophin receptors in human granulocytes and bone marrow cells--enhanced neurotrophin-4 expression induced by LTB4.

The expression of neurotrophin and neurotrophin receptor mRNAs in human granulocytes and bone marrow cells was examined using ribonuclease protection assay and reverse transcription-polymerase chain reaction. The granulocytes expressed mRNA coding for nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-4 (NT-4), but not neurotrophin-3 (NT-3). Moreover, the inflammatory mediator leukotriene B4 (LTB4) up-regulated the expression of NT-4 mRNA in granulocytes, but did not affect the expression of other neurotrophin mRNAs. Granulocytes generally lacked expression of mRNA coding for neurotrophin receptors. In contrast, human bone marrow cells consistently expressed mRNA for trkB (the BDNF and NT-4 receptor) and displayed variable expression of mRNA coding for trkA (the tyrosine kinase NGF receptor) and LNGFR (the low-affinity NGF receptor), whereas mRNA for trkC (the NT-3 receptor) was not expressed. Contrary to granulocytes, normal bone marrow cells generally expressed only low levels of mRNA encoding BDNF and NT-4. Expression of mRNA encoding NGF and NT-3 was not detected. However, significantly increased expression of BDNF mRNA was observed when bone marrow cells from patients with chronic myeloproliferative disorders (MPD) were analyzed. The results suggest that neurotrophins may act as granulocyte-derived effector molecules and that human bone marrow cells may be targets for these compounds, in particular BDNF and NT-4.

Bone Marrow Cells↗
PubMed1998

Novel enzymatic abnormalities in AML and CML in blast crisis: elevated leucocyte leukotriene C4 synthase activity paralleled by deficient leukotriene biosynthesis from endogenous substrate.

Leukotrienes (LT) are inflammatory mediators which can also exert regulatory effects on human myelopoiesis. We have studied the LT-producing capacity of freshly isolated leucocyte suspensions (containing blast cells in variable proportions) from 41 patients with acute myeloid leukaemia (AML) or chronic myeloid leukaemia (CML) in blast crisis (CMLbc) at diagnosis or relapse/resistant disease. Leucocyte suspensions from 19/29 AML patients (66%), and 2/12 CMLbc patients (17%; P = 0.012) demonstrated deficient capacity to synthesize LT from endogenous substrate after ionophore A23187 stimulation. Thus, these cells produced < 8 pmol LTB4+LTC4/10(6) cells (< 20% of mean LT formation in leucocyte suspensions from 18 healthy subjects). Addition of exogenous arachidonic acid did not normalize the LT synthesis in poor-producing cell suspensions. Purified, morphologically mature granulocytes from two AML patients also failed to produce normal amounts of LT. In leucocyte suspensions from the remaining 20 AML/CMLbc patients A23187 provoked LT biosynthesis, with markedly increased production of LTC4, but decreased LTB4 formation. Furthermore, elevated conversion of exogenous LTA4 to LTC4 was noted in the patient samples, independent of their capacity to produce LT after A23187 stimulation. The percentage of blast cells in patient white blood cell differential counts correlated inversely with ionophore-induced LT synthesis, but positively with the conversion of exogenous LTA4 to LTC4. The results suggest elevated LTC4 synthase activity and suppressed 5-lipoxygenase activity as novel enzymatic features of myeloid leukaemia patients with immature phenotype.

Acute Disease↗
PubMed1996

Electrospray-collision-induced dissociation mass spectrometry of mono-, di- and tri-hydroxylated lipoxygenase products, including leukotrienes of the B-series and lipoxins.

Collision-induced dissociation (CID) mass spectra were recorded on underivatized, hydroxylated lipoxygenase products, including S(S)-, 12(S)- and 15(S)-hydroxyeicosatetraenoic adds (HETE), leukotriene (LT) B4, LTB5, the LTB4 metabolites 20-OH-LTB4, 20-COOH-LTB4 and 10,11-dihydro-LTB4, the LTB4 isomers 6-trans-LTB4, 6-trans,12-epi-LTB4 and S(S),12(S)-dihydroxyeicosatetraenoic acid (diHETE) as well as S(S),6(R)-diHETE, 14(S), 15(R)-diHETE and lipoxin (LX) A4 and B4. Pseudomolecular [M-H]- parent ions were generated by electrospray ionization. The ions were accelerated to 4 keV, selected by the double focusing sectors Of 2 hybrid tandem mass spectrometer, decelerated to 400 eV and focused into a collision cell containing xenon. The resulting fragment ions were mass analysed by an orthogonal time-of-flight analyser. The CID spectra obtained were structurally informative allowing isomer differentiation.

Blood Platelets↗
PubMed1996

Breast cancer survival rates with mammographic screening: similar favorable survival rates for women younger and those older than 50 years.

PURPOSE: To evaluate the effect of a population-based mammographic screening program on breast cancer survival rates in women younger and in those older than 50 years of age. MATERIALS AND METHODS: A total of 56,881 women, aged 39-71 years, were invited to participate in mammographic screening one to four times during a 6 1/2-year period. RESULTS: A total of 671 cases of primary breast cancer were diagnosed, of which 472 (70%) cases were detected at screening. There was no substantial difference in stage distribution between women younger and those older than 50 years of age. The cumulative breast cancer survival rate for all women with breast cancer was 88% after 7 years; the cumulative breast cancer survival rates in women younger and in those older than 50 years of age were 92% and 87%, respectively. CONCLUSION: The similar breast cancer survival rates in women younger and in those older than 50 years suggest that mammographic screening can be effective in women aged 40-49 years.

Adult↗
PubMed1995

Phorbol ester-induced suppression of leukotriene C4 synthase activity in human granulocytes.

The effect of the protein kinase C activator, phorbol 12-myristate 13-acetate (PMA), on the metabolism of exogenous leukotriene (LT)A4 in human granulocytes was investigated. After incubation with LTA4 decreased levels of LTC4 but not LTB4 were observed in granulocyte suspensions pretreated with PMA. This finding could in part be ascribed to oxidative metabolism of LTC4, since PMA induced a rapid degradation of exogenously added LTC4. After blocking of LTC4 metabolism with the H2O2 scavenger catalase, a PMA-provoked suppression of the conversion of LTA4 to LTC4 was observed, indicating PKC-dependent regulation of LTC4 synthase activity. This effect, as well as PMA-induced degradation of LTC4 was prevented by specific protein kinase C inhibitors.

Calcimycin↗
PubMed1995

Receptor-mediated regulation of leukotriene C4 synthase activity in human platelets.

Human platelets possess a specific membrane-bound leukotriene (LT) C4 synthase, which catalyzes the conversion of LTA4 to LTC4. Stimulation of the receptors for thrombin, collagen or thromboxane A2 provoked inhibition of this enzyme, as judged by suppressed transformation of exogenous LTA4 to LTC4. Similarly, direct activation of protein kinase (PK) C with nanomolar concentrations of 4 beta-phorbol 12-myristate 13-acetate (PMA) inhibited the production of LTC4. Kinetic studies demonstrated that the inhibition induced by thrombin and PMA was non-competitive. Elevation of intracellular cAMP levels with carbacyclin did not affect basal LTC4 formation, but abolished the attenuation of platelet LTC4 synthase activity induced by the thromboxane receptor agonist U-46619. The unselective protein kinase inhibitor staurosporine prevented both receptor-mediated and PMA-induced suppression of LTC4 formation. In contrast, two selective PKC inhibitors, Ro 31-8220 and GF 109203X, reversed the inhibitory effect provoked by PMA, but failed to prevent thrombin-induced inhibition. Furthermore, the protein tyrosine phosphatase inhibitor, sodium orthovanadate, induced dose-dependent inhibition of LTC4 production in platelet sonicates. In conclusion, receptor-mediated activation of human platelets leads to decreased LTC4 synthase activity via phosphoregulation. Although the present results demonstrate that platelet LTC4 synthase can be regulated via PKC-dependent events, alternative mechanisms appears to be involved in the physiological regulation of this enzyme. The findings suggest the possible importance of protein tyrosine phosphorylations in this process.

Blood Platelets↗
PubMed1995

Liquid chromatography/mass spectrometry with collision-induced dissociation of arachidonic acid metabolites derivatized with aminobenzenesulphonic acid.

A fused-silica capillary high-performance liquid chromatography column (i.d. 0.25 mm) packed with octadecylsilane-bonded silica has been used on-line with continuous-flow negative-ion fast-atom bombardment (FAB) mass spectrometry for the separation and structural analysis of series of fatty acids and arachidonic acid metabolites derivatized with 4-aminobenzenesulphonic acid. Negative-ion FAB spectra of the derivatized lipids showed strong [M-H] pseudomolecular ions. Collision-induced dissociation of these anions produced structurally informative daughter ions, arising from charge-remote fragmentations.

Arachidonic Acids↗
PubMed1995

Ethanol affects leukotriene generation and leukotriene-induced functional responses in human polymorphonuclear granulocytes.

Since ethanol has been shown to inhibit the inflammatory response, we evaluated whether ethanol affected generation of leukotrienes in polymorphonuclear granulocytes (PMN) in vitro. Using the calcium ionophore A23187 as stimulus, the leukotriene B4 (LTB4) and leukotriene C4 (LTC4) generation were dose-dependently impaired by ethanol. No significant difference in the levels of the omega-oxidized metabolites was observed. However, the total LTB4 production (LTB4 plus omega-oxidized metabolites) was significantly decreased in the samples treated with ethanol. Furthermore, ethanol also modulated LTB4-induced functional responses. PMN aggregation, oxidative metabolism and elastase release were all inhibited in the presence of 1% ethanol (to 74 +/- 15%, 50 +/- 4% and 57 +/- 3% of controls, respectively). However, ethanol had no effect on intracellular calcium mobilization or on the change of the PMN membrane potential induced by either LTB4 or A23187. Thus, a possible mechanism for the reduced functional PMN responses in the presence of ethanol might be impaired generation of leukotrienes, but it is conceivable that ethanol impairs also other steps of the stimulus response coupling since the LTB4-induced functional responses were inhibited.

Calcimycin↗
PubMed1994

Expression of mRNA encoding neurotrophins and neurotrophin receptors in rat thymus, spleen tissue and immunocompetent cells. Regulation of neurotrophin-4 mRNA expression by mitogens and leukotriene B4.

The expression of neurotrophin and neurotrophin receptor mRNAs was examined using RNase protection assays and Northern-blot analysis in rat thymus, spleen tissue and immunocompetent mononuclear cells purified from these two organs. Nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin-4 mRNAs were all expressed in thymus and spleen tissue although at different levels, while immunocompetent cells expressed neurotrophin-3 and neurotrophin-4 mRNAs. Thymus and spleen tissue expressed mRNAs encoding the low-affinity nerve-growth-factor receptor, the non-neuronal TrkA I receptor, the truncated (kinase deficient) and full-length TrkB, and the TrkC receptor. Low-affinity nerve-growth-factor receptor and non-neuronal TrkA I mRNAs were detected in both thymus and spleen immunocompetent cells. In addition, thymus cells expressed neuronal TrkA II mRNA and spleen cells expressed truncated TrkB mRNA. The expression of TrkA I and TrkA II mRNAs was enhanced in both thymus and spleen cells after cell culture. Enhanced levels of neurotrophin-4 mRNA were observed in spleen immunocompetent cells after adrenalectomy. Moreover, the expression of neurotrophin-4 mRNA was up-regulated after stimulation of immune cells with the mitogens concanavalin A or lipopolysaccharide or with the inflammatory mediator leukotriene B4. This suggests that neurotrophin-4 could be secreted by immunocompetent cells and may be involved in inflammatory processes.

Adrenalectomy↗