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Biomedical subjects

K K Eklund

Publications and source records attributed to K K Eklund.

At least 19 recordsLinked to original sources
PubMed2005

Chemically modified tetracycline (CMT)-3 inhibits histamine release and cytokine production in mast cells: possible involvement of protein kinase C.

OBJECTIVE: To find novel inhibitors of mast cell function we have studied the effect of a potent, non-antimicrobial, chemically modified tetracycline, CMT-3 or COL-3, on key functions of mast cells. METHODS AND RESULTS: In the presence of 25 microM CMT-3, the 48/80-induced histamine release from rat serosal mast cells was inhibited significantly, to 43.0 +/- 7.3% of control. Similarly, the activation-induced secretion of TNF-alpha and IL-8 by HMC-1 cells were decreased in the presence of 25 microM CMT-3 to 13.5 +/- 4.1% and 9.7 +/- 1.1% of control, respectively. CMT-3 did not cause intracellular accumulation of TNF-alpha but instead it reduced the expression of TNF-alpha mRNA in HMC-1 cells. Moreover, CMT-3 was found to significantly inhibit the protein kinase C (PKC) activity with IC(50) value of 31 microM. CMT-3 inhibited effectively both human recombinant PKCalpha and PKCdelta isoforms. In comparison to doxycycline, CMT-3 was more effective as an inhibitor of both cytokine production and PKC activity. CONCLUSIONS: Considering the central role of PKC in mast cell activation, PKC inhibition could, at least partially, explain the observed inhibitory effects of CMT-3. The inhibition of the key proinflammatory functions of mast cells by CMT-3 suggests its potential clinical usefulness in the treatment of allergic and inflammatory disorders.

Animals↗
PubMed2005

Inhibition of c-kit tyrosine kinase by imatinib mesylate induces apoptosis in mast cells in rheumatoid synovia: a potential approach to the treatment of arthritis.

BACKGROUND: Mast cells have been implicated in the pathogenesis of arthritis, but elucidation of their precise role has been hampered by a lack of efficient and selective inhibitors of their function. OBJECTIVE: To elucidate the role of mast cells in the pathogenesis of rheumatoid arthritis (RA) and to assess whether apoptosis of cultured and synovial tissue mast cells can be induced by inhibiting mast cell growth factor receptor, c-kit tyrosine kinase. METHODS AND RESULTS: Double staining with tumour necrosis factor (TNF) alpha and tryptase antibodies showed the presence of TNFalpha positive mast cells in human rheumatoid synovial tissue. Selective activation of mast cells by anti-IgE resulted in production of TNFalpha in synovial tissue cultures. Inhibition of the c-kit tyrosine kinase with imatinib mesylate (1.0-10 micromol/l) induced profound apoptosis in cultured mast cells as judged by typical apoptotic morphology, increased number of apoptotic nucleosomes, and activation of caspases 8 and 9. Importantly, imatinib also induced apoptosis of mast cells in explant cultures of synovial tissue obtained from patients with RA as judged by a TUNEL assay. Inhibition of c-kit tyrosine kinase was accompanied by significant reduction of TNFalpha production in synovial tissue cultures. CONCLUSION: Mast cells may have a role in the pathogenesis of RA, and inhibition of c-kit may be a new means of inhibiting mast cell activity and of abrogating the contribution of mast cells to synovial inflammation in RA.

Animals↗
PubMed2001

Ethanol infusion increases ANP and p21 gene expression in isolated perfused rat heart.

Whether alcohol-induced heart failure is caused by a direct toxic effect of ethanol, metabolites, or whether it is a secondary result of neurohumoral, hormonal, or nutritional factors is not clear. To address this question a Langendorff retrograde coronary perfusion model of rat heart was used to study the effect of 0.5% (v/v) ethanol (n = 7) and 0.5 mM acetaldehyde (n = 9) on left ventricular expression of ANP, BNP, p53, p21, TNF-alpha,bax, bcl-2 as well as on DNA-fragmentation. Ethanol infusion of 150 min duration significantly induced both ANP and p21 mRNA expression of ventricular myocardium compared with hearts infused with vehicle (n = 8). Acetaldehyde did not exert any significant effects on any of the parameters studied, although the mean expression of TNF-alpha tended to be lower in the acetaldehyde-treated hearts than in control hearts. No evidence of increased DNA-fragmentation was found in ethanol or acetaldehyde treated groups. We conclude that ethanol per se is capable of inducing genes associated with hypertrophy and impaired function of the heart whereas a significant apoptosis is not involved in the initial phase of alcohol-induced cardiac injury.

Acetaldehyde↗
PubMed2001

Effect of age and body weight on neurohumoral variables in healthy Cavalier King Charles spaniels.

OBJECTIVE: To evaluate the effect of age and body weight on several neurohumoral variables that are commonly altered in heart failure in Cavalier King Charles Spaniels. ANIMALS: 17 healthy privately owned Cavalier King Charles Spaniels, 10 males and 7 females, ranging in age from 0.4 to 9.7 years, and ranging in body weight from 6.6 to 12.2 kg. PROCEDURE: The clinical condition of the dogs was evaluated by physical examination, thoracic radiography, and echocardiography. Plasma nitrate and nitrite (P-NN), N-terminal atrial natriuretic and brain natriuretic peptides (NT-ANP and BNP, respectively), endothelin (ET-1), urine cyclic guanosine monophosphate (U-cGMP), and urine nitrate and nitrite (U-NN) concentrations were analyzed. RESULTS: Plasma concentrations of NT-ANP and P-NN increased significantly with age, but plasma NT-ANP and P-NN also correlated significantly, irrespective of age. A modest increase of left atrial size did not explain the increase of NT-ANP and P-NN with age. Concentration of ET-1 correlated positively with heart rate; heart rate did not change with age. Weight had a negative impact on NT-ANP, P-NN, and U-cGMP concentrations and left atrial relative size. CONCLUSIONS AND CLINICAL RELEVANCE: Age-matched controls are essential for evaluation of NT-ANP and P-NN concentrations and left atrial size. Weight may alter reference values of plasma NT-ANP, P-NN, and urine cGMP concentrations. Natriuretic peptides can be used as further evidence that heart failure exists. The increased plasma concentrations of NT-ANP (but not BNP) and P-NN with aging reflect neurohumoral physiologic changes that must be distinguished from pathologic changes in patients with heart failure.

Age Factors↗
PubMed2000

Ethanol inhibits IgE-induced degranulation and cytokine production in cultured mouse and human mast cells.

Activated mast cells (MC) can produce a wide variety of potent inflammatory mediators. Excessive alcohol consumption is known to lead to immune deficiency and propensity for pneumonias in particular. As MCs are important in the first line of defence of mucosal membranes we have studied the effect of ethanol (EtOH) on several MC functions. EtOH attenuated dose dependently IgE-induced degranulation of mouse bone marrow derived mast cells (mBMMC) as reflected by the release of granule associated beta-hexosaminidase (beta-hex). A mean of 26 +/- 7% inhibition of beta-hex release was observed in the presence of 5/1000 (86 mM) EtOH and nearly complete inhibition in the presence of 20/1000 (344 mM) ethanol. The IgE-induced degranulation of mBMMC cultured with EtOH for seven days was inhibited to a similar degree as the degranulation of mBMMC exposed to EtOH for only one hour. Inclusion of 5/1000 (86 mM) ethanol in the medium reduced tumour necrosis factor (TNF)-alpha and interleukin (IL)-8 production in human mast cell line (HMC-1) cells by 55 +/- 7% and 19 +/- 5%, respectively, and the presence of 20/1000 (344 mM) ethanol inhibited the expression 81 +/- 12% and 59 +/- 14% respectively. These results suggest that, in contrast to previous assumption, ethanol inhibits several critical MC functions at least in vitro. This inhibition of mediator, and cytokine release in particular, could contribute to the immune deficiency associated with chronic alcohol consumption.

Animals↗
PubMed1998

Mast cells in bronchiectasis.

Bronchiectasis (BE) is a chronic severe inflammatory lung disease characterized by frequent bacterial infections and polymorphonuclear neutrophil-dominated inflammatory reaction. We have attempted to elucidate the role of mast cells (MCs) in BE lung inflammation by measuring in the bronchoalveolar lavage fluid (BALF) the MC-derived tryptase levels by radioimmunoassay and immunoblotting and also by measuring the tryptase-like activities in 36 BE patients and in 14 healthy controls. The amount of MC in the lung tissue was assessed by immunohistochemical staining of resected lung tissue samples. Based on the clinical and radiological parameters the patients were divided into subgroups according to the severity of the disease. The MC tryptase concentrations (microg/L; median (range)) in BALF of BE patients were higher compared to healthy controls (4.7(1.4-20.1) and 2.0 (0.1-3.5), respectively, P < 0.01). Tryptase concentrations in the groups of mild, moderate and severe BE were 3.8 (0.9-10.8), 4.3 (3.0-12.6) and 9.6 (1.2-20.1), respectively. All the values differed significantly from those observed in the healthy controls. The tryptase-like activities (nmol/sec/L) in BE patients were also markedly increased (174 (31-2874)) compared to healthy controls (28 (9-45) P < 0.0001). The tryptase-like activities in the patient subgroups were 45 (36-598) in mild, 91 (31-1437) in moderate and 1336 (37-2874) in severe BE. Again, all values differed significantly from those observed in the healthy controls. Moreover, immunoblot experiments disclosed the most intensive immunoreactivity of the 27.5 kD tryptase monomer in BALF of patients with severe BE followed by weaker immunoreactivity in groups of moderate and mild BE and in healthy controls. No significant difference could be observed in the amount of tryptase-positive cells between BE patients and controls. However, the presence of degranulated MCs was more evident in BE lung tissue. Significant correlation could also be observed between the degree of activation of latent procollagenase and tryptase concentration (r = 0.8, P = 0.0004) in BALF of individual BE patients. The observed strong correlation between tryptase levels and disease severity suggests that MCs may be involved in the inflammatory reaction in the BE lung. Importantly, the high levels of tryptase, observed also in patients with mild BE, suggests that activation of and proteinase release from MCs may be one of the reasons for the perpetuation of tissue injury even during the clinically quiescent periods in BE.

Adult↗
PubMed1997

Glucocorticoids inhibit the cytokine-induced proliferation of mast cells, the high affinity IgE receptor-mediated expression of TNF-alpha, and the IL-10-induced expression of chymases.

Mast cells are a heterogeneous family of immune cells that, when activated through their high affinity IgE receptors (Fc epsilonRI), release various granule mediators (e.g., neutral proteases and serglycin proteoglycans) and proinflammatory cytokines (e.g., IL-6 and TNF-alpha). We and others have shown that the growth and differentiation of immature, nontransformed mouse bone marrow-derived mast cells (mBMMC) can be regulated in vitro by IL-3, IL-10, and c-kit ligand. We now report that glucocorticoids inhibit the c-kit ligand- and IL-3-induced proliferation of mBMMC, the Fc epsilonRI-mediated expression of TNF-alpha, and the IL-10-mediated expression of the two chymases designated mouse mast cell protease (mMCP)-1 and mMCP-2. In contrast, glucocorticoids induce mBMMC to increase their expression of serglycin proteoglycan and carboxypeptidase A. As assessed by nuclear run-on and RNA blot analyses, dexamethasone inhibited the IL-10-mediated expression of mMCP-1 and mMCP-2, primarily by inducing rapid degradation of their transcripts. The stimulative effect on serglycin proteoglycan expression and the inhibitory effect on chymase expression were dose and time dependent and glucocorticoid specific. These findings indicate that glucocorticoids exert profound and diverse effects on the growth, cytokine expression, and granule differentiation of mouse mast cells, and that at least some of this regulation occurs through a post-transcriptional mechanism.

Animals↗
PubMed1997

Role of nitric oxide in Sjögren's syndrome.

OBJECTIVE: To measure levels of salivary nitrite (NO2-) and to localize nitric oxide synthases (NOS) in the labial salivary glands (LSGs) of patients with Sjögren's syndrome (SS). METHODS: NO2- was measured by the Griess reaction. LSGs were analyzed using NADPH-diaphorase histochemical and immunohistochemical studies to determine the constitutive NOS (neuronal [ncNOS] and endothelial [ecNOS]) and inducible NOS (iNOS) isoforms. RESULTS: The NO2- concentration (mean +/- SEM 307 +/- 51 microM versus 97 +/- 16 microM; P < 0.05) and output (166 +/- 46 nmoles/minute versus 37 +/- 7 nmoles/minute) were increased in SS patients compared with healthy control subjects. NADPH-diaphorase was found in some nerve fibers and endothelial cells, and, in SS, was found in myoepithelial, acinar, and ductal epithelial cells, but in only a few inflammatory cells. In SS, ncNOS-immunoreactive nerve fibers were sparse and ecNOS was found in a minority of the CD31-positive vascular endothelial cells and acinar cells, whereas iNOS was localized in myoepithelial, acinar, and ductal epithelial cells, often together with tumor necrosis factor alpha. CONCLUSION: Nitrite was found in normal human saliva. NO produced by ncNOS probably acts as a nonadrenergic, noncholinergic neurotransmitter, whereas that produced by ecNOS exerts a vasodilatory effect. SS patients had increased NO2- concentrations, with most of the superfluous salivary NO being produced not by the immigrant inflammatory cells, but rather, by the resident salivary gland cells. NO may contribute to inflammatory damage and acinar cell atrophy in SS.

Adult↗
PubMed1997

Potentiative effects of neutral proteinases in an inflamed lung: relationship of neutrophil procollagenase (proMMP-8) to plasmin, cathepsin G and tryptase in bronchiectasis in vivo.

We attempted to study the possible relationships between neutrophil-type procollagenase/pro-matrix metalloproteinase (MMP-8) and the serine proteinases plasmin, cathepsin G and tryptase in bronchiectasis. The presence of the plasmin/plasminogen system and plasmin-, cathepsin G- and tryptase-like activities were compared to the activity of endogenously activated MMP-8 in bronchoalveolar lavage (BAL) fluid in 38 bronchiectasis patients and in 14 healthy controls by means of immunohistochemistry, Western-blot and substrate-based functional assays. In contrast to cathepsin G- and tryptase-like activities, the plasmin/plasminogen activator system in BAL fluid was observed to have a relatively weak activation stage and no correlation with disease severity. Neither plasmin-like activities nor concentrations of plasminogen activators from the bronchiectatic patients differed significantly from the values of healthy controls. Immunolocation of plasminogen activator inhibitor-1 showed a marked, but not significant, increase in bronchiectatic lung as compared to controls. In contrast to cathepsin G- and tryptase-like activities, with their strong and significant correlation with endogenously activated collagenase (r=0.9; p=0.0001; and r=0.6; p=0.03, respectively), no correlations were observed between plasmin-like and endogenously activated collagenase (r=0.3; p=0.2) in bronchiectasis. These findings suggest that cathepsin G- and tryptase-like activities may act as potent pro-matrix metalloproteinase-8 activators in patients with bronchiectasis, whereas the plasminogen activator/plasmin cascade was shown to be down-regulated.

Adolescent↗
PubMed1996

Mast cell-derived tryptase in odontogenic cysts.

Inflammatory and developmental cysts of the jaws are relatively common bone destructive lesions in the human maxillofacial skeleton but their pathogenesis is still poorly understood. In this study the role of mast cells (MC), and mast cell tryptase in particular, was evaluated in the pathophysiology of bone resorption and jaw cyst formation in different types of cysts. The distribution of MC and the amount of tryptase in histological tissue sections were determined by immunohistochemistry using monoclonal antihuman tryptase antibodies and the results were quantitated by using an image analyzing system. The amount of tryptase was further studied by Western-blotting and measurement of trypsin-like activity from the neutral salt extracts obtained from different types of jaw cysts. In contrast to control tissue, high trypsin-like activities and abundant immunoreactive tryptase were observed in the extracts of all types of cysts studied (radicular, dentigerous and keratocyst). In tissue sections the highest amount of tryptase-positive staining was observed in radicular cysts (mean 6.2% of reference area) and the lowest amount in keratocysts (mean 2.1% of reference area, P < 0.01). MC were found to be located in inflammatory cell-rich tissue areas and just beneath the cyst epithelium. Importantly, MC located at the border of bone were observed to be degranulated, indicating high activity of MC and release of tryptase at the regions of early bone destruction. Based on previous findings addressing the role of mast cell tryptase in proteolytic cascades, and the known association of MC with osteoporosis, we suggest that mast cells and mast cell tryptase may contribute significantly to jaw cyst tissue remodelling during growth of a cyst, and to the destruction of the surrounding bone, resulting in jaw cyst expansion.

Adolescent↗
PubMed1996

Mast cells in loosening of totally replaced hips.

This study evaluated mast cells in tissue around loose total hip implants. Interface and pseudocapsular tissues were obtained from 6 patients with a loose hip prosthesis. Mast cells were labeled with monoclonal mouse antihuman antibodies against tryptase and chymase in avidin-biotin-peroxidase complex staining and were quantitated morphometrically by means of a semiautomatic Kontron image analyzer. Almost all mast cells in situ were chymase-positive and tryptase-positive connective tissue cells. The mean number of such cells per mm2 of tissue increased in this rank order: interface (9.98 +/- 5.03 cells) < pseudocapsule (15.85 +/- 4.99 cells) < control knee synovium (25.08 +/- 8.64 cells). Mast cells in periprosthetic tissue, in contrast to normal knee synovial tissue, exhibited granule release. Mast cells around loose hip prostheses appeared to be activated by connective tissue mast cells. These were found in diminished numbers and in a degranulated state in the interface tissue between implant and bone. Mast cell activation in loco may thus lead to significant local production and/or release of proinflammatory mast cell mediators. Prevention of mast cell activation (degranulation) could prove useful in the postponement of loosening of the totally replaced hip.

Aged↗
PubMed1994

Mouse bone marrow-derived mast cells (mBMMC) obtained in vitro from mice that are mast cell-deficient in vivo express the same panel of granule proteases as mBMMC and serosal mast cells from their normal littermates.

The ear, skin, and purified serosal mast cells of WBB6F1/J-(+/+) (WB-(+/+)) and WCB6F1/J-(+/+) (WC-(+/+)) mice contain high steady-state levels of the transcripts that encode mouse mast cell protease (mMCP) 2, mMCP-4, mMCP-5, mMCP-6, and mouse mast cell carboxypeptidase A (mMC-CPA). In contrast, no mast cell protease transcripts are present in abundance in the ear and skin of WBB6F1/J-W/Wv (W/Wv) and WCB6F1/J-Sl/Sld (Sl/Sld) mice which are mast cell-deficient in vivo due to defects in their c-kit and c-kit ligand genes, respectively. We now report that the immature bone marrow-derived mast cells (mBMMC) obtained in vitro with recombinant interleukin 3 (rIL-3) or WEHI-3 cell conditioned medium from WB-(+/+), WC-(+/+), W/Wv, and Sl/Sld mice all contain high steady-state levels of the mMCP-2, mMCP-4, mMCP-5, mMCP-6, and mMC-CPA transcripts. As assessed immunohistochemically, mMCP-2 protein and mMCP-5 protein are also present in the granules of mBMMC from WB-(+/+), WC-(+/+), and W/Wv mice. That Sl/Sld and W/Wv mBMMC contain high steady-state levels of five granule protease transcripts expressed by the mature serosal, ear, and skin mast cells of their normal +/+ littermates suggests that c-kit-mediated signal transduction is not essential for inducing transcription of these protease genes. Because rIL-4 inhibits the rIL-10-induced expression of mMCP-1 and mMCP-2 in BALB/cJ mBMMC, the ability of rIL-4 to influence protease mRNA levels in WC-(+/+) mBMMC and W/Wv mBMMC was investigated. Although rIL-10 induced expression of the mMCP-1 transcript in WC-(+/+) and W/Wv mBMMC, rIL-4 was not able to suppress the steady-state levels of the mMCP-1 transcript or any other protease transcript in these cultured mast cells. Thus, not only do BALB/cJ mBMMC express fewer granule proteases than mBMMC from mast cell-deficient strains and their normal littermates but the subsequent induction of late-expressed proteases in BALB/cJ mBMMC is more tightly regulated by IL-3 and IL-4.

Animals↗
PubMed1993

Induction by IL-9 and suppression by IL-3 and IL-4 of the levels of chromosome 14-derived transcripts that encode late-expressed mouse mast cell proteases.

Immature, rIL-3-dependent mouse bone marrow-derived mast cells (BMMC) contain high steady-state levels of the mouse mast cell protease (mMCP) 5 transcript but undetectable levels of the mMCP-1, mMCP-2, or mMCP-4 transcripts even though all four of their genes reside at a locus on chromosome 14. These mast cells can be induced by recombinant c-kit ligand (rKL) to obtain high steady-state levels of the mMCP-4 transcript and by rIL-10 to obtain high steady-state levels of the mMCP-1 and mMCP-2 transcripts. rIL-3 and rKL both elicit the differentiation of progenitor cells into immature BMMC and then stimulate their proliferation. We now report that although rIL-9 alone has no effect on BMMC proliferation as assessed by their incorporation of [3H]thymidine, rIL-9 in combination with rKL enhances the long term viability of BMMC. Furthermore, rIL-9 in the presence of rKL stimulates mouse BMMC to undergo a phenotypic change by inducing accumulation of high steady-state levels of the mMCP-1 and mMCP-2 transcripts. In contrast, in BMMC, the presence of rIL-4 suppresses the rIL-9-induced accumulation of the mMCP-1 and mMCP-2 transcripts, the rIL-10-induced accumulation of the mMCP-1 and mMCP-2 transcripts, and the rKL-induced accumulation of the mMCP-4 transcript, but not the rIL-3-induced accumulation of the mMCP-5 transcript. The presence of rIL-3 also suppresses the rIL-9-induced accumulation of the mMCP-1 and mMCP-2 transcripts. Because of their counter-regulatory actions on the steady-state levels of transcripts that encode three late-expressed serine proteases in BALB/cJ mice, rIL-4 and rIL-3 both inhibit the final stages of differentiation and maturation of mast cells. Because rIL-4, unlike rIL-3, is neither an inducer of early-expressed proteases nor alone a proliferative factor for BMMC, the counterregulatory actions of rIL-3 and rIL-4 on differentiation and maturation of these mouse mast cells are independent of their other functions.

Animals↗
PubMed1992

Conformation of phosphatidylcholine in neat and cholesterol-containing liquid-crystalline bilayers. Application of a novel method.

The conformation of phosphatidylcholine in liquid-crystalline bilayers was studied with a novel, high-resolution method employing phosphatidylcholine species containing pyrenyl moieties in both acyl chains of variable length. Analysis of the intramolecular pyrene-pyrene collision data obtained for 30 such species in terms of a simple geometrical model showed that the sn-1 acyl chain penetrates, on the average, 0.84 +/- 0.11 methylene units (0.8 A) deeper into the bilayer than the sn-2 chain at 22 degrees C. A similar value was obtained at 37 degrees C. Since the penetration difference of the sn-1 and sn-2 acyl chains is inherently coupled to the conformation of the glycerol moiety, these data mean that the glycerol moiety of phosphatidylcholine is, on the average, only moderately tilted with respect to the bilayer plane in the liquid-crystalline state. This contrasts the perpendicular orientation observed previously for phosphatidylcholine crystals [Pearson, R. H., & Pascher, I. (1979) Nature 281, 499-501]. Importantly, addition of 50 mol % cholesterol, which is known to reduce dramatically the interactions between phosphatidylcholine molecules in bilayers, had only a small effect on the penetration difference of the acyl chains, strongly suggesting that the conformation of phosphatidylcholine in the liquid-crystalline state is determined largely by intramolecular, rather than intermolecular, interactions.

Chemistry, Physical↗