Biomedical subjects

Wei Liu

Publications and source records attributed to Wei Liu.

At least 379 records · Page 21Linked to original sources

PubMed2003

[The experimental study of tissue engineered autologous cartilage using chitosan-gelatin complex scaffolds].

OBJECTIVE: To investigate whether man-made porous chitosan-gelatin complex scaffold was a appropriate scaffold for tissue engineering cartilage. METHODS: Chondrocytes isolated from Changfeng crossbred swines' auricular cartilage were seeded onto chitosan- gelatin scaffolds to be cultured in a three dimensional environment. The chondrocyte- polymer constructs were implanted into the subcutaneous tissue of the swines' abdomenal wall. Specimens were harvested and analyzed by gross observation, histology, type II collagen immunohistochemistry and biochemistry after 10 and 16 weeks in vivo respectively. RESULTS: H.E staining showed cartilage was formed, and chondrocytes were enclosed in lacuna with histological characteristics similar to natural cartilage. Some clusters of neocartilage surrounded by fibrous tissues were observed. Elastic fibres were observed in the mesenchyma of cartilage 16 weeks after by Vehoeff's staining. Immunohistochemical staining of the neocartilage with anti- type II collagen showed the presence of type II collagen in the ECM of tissue engineered cartilage. The proteoglycans content in tissue engineered cartilage was close to that of natural swine's auricular cartilage. CONCLUSION: The experiments demonstrated that using chitosan-gelatin complex scaffold we can generate autologous cartilage on animals with normal immune system. Porous chitosan- gelatin complex scaffolds may be a suitable scaffolds for tissue engineered cartilage.

Animals↗

PubMed2003

[Glucose uptake of activated platelets and the influence by integrin antibodies].

OBJECTIVE: To study the signal transduction in the course of energy metabolism of platelets, and to provide a new theoretical basis for clinical application of the anti-activation of platelets by the monoantibody of integrin GPIIb/IIIa. METHODS: With or without the block of integrin GPIIb/IIIa monoantibody 10E5 and/or integrin alpha v beta 3 monoantibody 609, the uptake rate of tritium-labeled 2-deoxyglucose([3H]2-DG) by platelets activated by thrombin was counted in a liquid scintillation counter. The relationship between the energy metabolism of platelets and platelet integrin was investigated by the course of glucose uptake of individual vivo platelets. RESULTS: Compared with unactivated platelets, the glucose uptake of activated platelets increased, and it could be blocked by monoantibody 10E5 and partly blocked by 609. CONCLUSION: The glucose uptake of activated platelets can be suppressed by monoantibody 10E5, and the intergrin family is associated with the signal transduction of platelet energy metabolism. Integrin GPIIb/IIIa may play an important role in the procedure of platelet energy metabolism.

Blood Glucose↗

PubMed2003

[Microsurgery for intracranial aneurysm, clinical analysis of 1,041 cases].

OBJECTIVE: To study the effect of microsurgery on incranial aneurysm and factors influential in prognosis. METHODS: A retrospective analysis was made on the clinical data of 1,041 patients, 505 males and 536 females, aged 44.2 +/- 12.6, with incranial aneurysm treated by microsurgery 1988 approximately 2001, including clipping of aneurysm (982 cases, 94.3%), isolating of the aneurysm (32 cases, 3.1%), and coating of the aneurysm (27 cases, 2.6%). RESULTS: 93 patients (8.9%) had multiple aneurysms. 357 aneurysms (31.2%) were in the posterior communicating artery, 261 (22.8%) in the anterior communicating artery, 210 (18.4%) in the internal carotid artery, 158 (13.8%) in the middle cerebral artery, 63 (5.5%) in the anterior cerebral artery, 59 (5.2%) in the vertebral-basilar artery, and 35 (3.1%) in the posterior cerebral artery. The overall operative mortality was 1.8%. Angiography performed post-operationally showed that the aneurysm was occluded in 978 patients (99.6%). The prognosis was related to the age of patient (P = 0.001), Hunt and Hess grading before operation (P = 0.001), diameter of aneurysm (P = 0.000), and whether the aneurysm ruptures during operation (P = 0.006), and was not related to the gender of patient (P = 0.059). CONCLUSION: Clipping of the aneurysm is considered the best treatment. Microinvasive neurosurgery has improved significantly the effect of treatment of intracranial aneurysm. Factors influencing prognosis after operation include the age of patient, Hunt and Hess grading before operation, diameter of aneurysm, and whether the aneurysm ruptures during operation.

Adolescent↗

PubMed2003

[Inhibiting scar formation in rat cutaneous wounds by blocking TGF-beta signaling].

OBJECTIVE: TGF-beta plays a key role in wound scarring. This study explored the possibility of using gene therapy to inhibit wound scarring by blocking TGF-beta signaling. METHODS: In vitro, human normal dermal fibroblasts were infected with recombinant adenoviruses of truncated TGF-beta receptor II (tTGF-betaRII, 100 pfu/cell) and beta-galactosidase (beta-gal, 100 pfu/cell), and their effects on regulating TGF-beta1 gene expression were analyzed by Northern blot. For gene therapy, beta-gal and tTGF-betaRII viruses (1 x 10(9) pfu)were injected intradermally at left and right side of dorsal skin of newborn Sprague-Dawley rats (n = 15) respectively. A full-thickness incisional wound (0.5 cm long) was created at the injection sites of each rat 2 days post-injection. An incisional wound was similarly created in the middle part of the dorsal skin of tTGF-betaRII transgenic mice (n = 5) and control mice (n = 5). Wound tissues of rats and mice were harvested at various time points post-wounding for histological and immunohistochemical analysis. Scar area in tissue section was measured by Image-Pro Plus software. RESULTS: Over-expression of tTGF-betaRII markedly reduced TGF-beta1 gene expression in dermal fibroblasts. Adenovirus mediated gene expression in skin reached a peak level 2 - 3 days post-injection, and decreased gradually at 5 - 7 days. Two weeks post-wounding, histology and quantitative analysis demonstrated that relative scar area in the wounds of transgenic mice and control mice were 136,969.8 +/- 66,339 and 474,641.6 +/- 227,396 respectively, the scar area of transgenic wounds was 29 percent of control area (P < 0.05). In all rats, wounds transfected with tTGF-betaRII gene healed with much less scarring (relative scar area 128,311.2 +/- 36,764.6) than control wounds (251,189.1 +/- 62,544.7) of the same rat, with a 45% reduction of scar area in average (P < 0.001). In addition, the tTGF-betaRII expression also decreased inflammation and TGF-beta1 production in treated wounds, and promoted the repair of panniculus muscle in treated wounds. CONCLUSIONS: Adenovirus mediated over-expression of tTGF-betaRII can block TGF-beta signaling and inhibit wound scarring, and thus can serve as a gene therapy strategy to control wound scarring.

Adenoviridae↗

PubMed2003

Bone morphogenetic protein 4 (BMP4): a regulator of capsule chondrogenesis in the developing mouse inner ear.

Formation of the cartilaginous otic capsule is directed by otic epithelial-periotic mesenchymal interactions. In response to induction by otic epithelium, condensations of mesenchyme appear in the periotic region and form a chondrified otic capsule that serves as the template for the subsequent formation of the endochondral bony labyrinth. Previous studies indicate that members of the transforming growth factor beta superfamily, including transforming growth factor beta(1), participate in guiding these tissue interactions. In this study, we report the localization of bone morphogenetic protein 4 (BMP4) to the mesenchymal and epithelial-derived tissues of the mouse inner ear between 10.5 and 14 days of embryonic development. We demonstrate modulation of chondrogenesis in cultured mouse periotic mesenchyme by exogenous BMP4 protein and investigate the function of endogenous BMP4 in otic capsule chondrogenesis. We show that in the presence of the BMP antagonist, Noggin, otic capsule chondrogenesis is suppressed in culture in a dose-dependent manner. Consistent with this finding, addition of BMP4-specific antisense oligonucleotide to cultures of mouse periotic mesenchyme containing otic epithelium decreases levels of endogenous BMP4 protein and suppresses the chondrogenic response of the cultured periotic mesenchyme, providing evidence of the necessity for BMP4 in mediating otic capsule chondrogenesis. Supplementation of either Noggin- or BMP4 antisense oligonucleotide-treated cultures with BMP4 protein can restore the extent of chondrogenesis to normal levels. Our findings support BMP4 as an essential mediator of chondrogenesis in the developing otic capsule in situ.

Animals↗

PubMed2003

Impact of perioperative treatment of recombinant human growth hormone on cell immune function and intestinal barrier function: randomized, double-blind, controlled trial.

The objective of this study was to evaluate the effects of recombinant human growth hormone (GH) on cell immune function, intestinal barrier function, and outcome. A placebo-controlled randomized double-blind trial was performed, with 20 patients undergoing abdominal surgery enrolled in the study. The patients in the study group received GH (0.3 IU/kg/day) subcutaneously from day 3 before operation until day 7 after operation. The patients in the control group received placebo injections. All the patients were given isonitrogenic (0.15 g N/kg/day) and isocaloric (20 kcal/kg/day) parenteral nutrition from preoperative day 1 through postoperative day (POD) 6. The serum GH and insulin-like growth factor-1 (IGF-1) levels, intestinal permeability, peripheral CD4+/CD8+ lymphocyte subsets, and routine blood and biochemistry analyses were evaluated before and after GH treatment. In the study group a significant increase in serum levels of GH and IGF-1 was observed on PODs 3 and 7. A significant decrease in the CD4+ subset population and the CD4+/CD8+ ratio was observed in the control group on POD 7 compared with preoperative studies, whereas no change was observed in the study group. The lactulose/mannitol excretion (L/M) ratio in the control group was elevated significantly on POD 7 compared with that before operation ( p = 0.01), whereas the L/M ratio in the study group did not change compared to preoperative values ( p = 0.08). No adverse reactions were related to the administration. There were no differences observed in operation-related complications or postoperative hospital stays between the two groups. This small pilot study suggests that GH attenuated the depression in cellular immunity following surgical stress and possibly reduced the increase in intestinal permeability that occurs following operation. Further studies of a large group of patients are needed to determine if these changes can be translated into improved outcome in surgical patients.

Adult↗

PubMed2003

Role of side-chain conformational entropy in transmembrane helix dimerization of glycophorin A.

Dimerization of the transmembrane domain of glycophorin A is mediated by a seven residue motif LIxxGVxxGVxxT through a combination of van der Waals and hydrogen bonding interactions. One of the unusual features of the motif is the large number of beta-branched amino acids that may limit the entropic cost of dimerization by restricting side-chain motion in the monomeric transmembrane helix. Deuterium NMR spectroscopy is used to characterize the dynamics of fully deuterated Val80 and Val84, two essential amino acids of the dimerization motif. Deuterium spectra of the glycophorin A transmembrane dimer were obtained using synthetic peptides corresponding to the transmembrane sequence containing either perdeuterated Val80 or Val84. These data were compared with spectra of monomeric glycophorin A peptides deuterated at Val84. In all cases, the deuterium line shapes are characterized by fast methyl group rotation with virtually no motion about the C(alpha)-C(beta) bond. This is consistent with restriction of the side chain in both the monomer and dimer due to intrahelical packing interactions involving the beta-methyl groups, and indicates that there is no energy cost associated with dimerization due to loss of conformational entropy. In contrast, deuterium NMR spectra of Met81 and Val82, in the lipid interface, reflected greater motional averaging and fast exchange between different side-chain conformers.

Computer Simulation↗

PubMed2003

Measured summertime concentrations of particulate components, Hg0, and speciated polycyclic aromatic hydrocarbons at rural sites in New York State.

Daily PM2.5 samples, Hg0 and speciated polycyclic aromatic hydrocarbon (PAH) were simultaneously collected at Potsdam and Stockton site in NY during the summers of 2000 and 2001. Samples for determination of the mass concentration and chemical composition of the PM2.5 were obtained with a speciation network PM2.5 sampler. Chemical composition including trace elemental composition, water-soluble ions, and elemental carbon were analyzed. Elemental mercury and PAHs were sampled separately. Daily PM2.5 concentrations ranged from 0.47 to 53.7 microg m(-3) at the Potsdam site, and from 0.82 to 47.23 microg m(-3) at the Stockton site with large daily differences between the two sites. Potsdam consistently had lower mass values than Stockton. The greatest contributors to the PM2.5 mass (generally >0.1 microg/m(3)) were sulfate, nitrate, ammonium, and BC at both sites. Seventeen PAHs were identified at each site in 2000 and the average total concentrations were 3.2 ng/m(3) and 2.9 ng/m(3) at the Potsdam and Stockton sites, respectively. The mean vapor phase mercury concentration at the Potsdam site (2.4 +/-1.2 ng m(-3), n=93) was higher than that at the Stockton site (1.2 +/- 1.0 ng m(-3), n=60) in 2000, whereas in 2001, the average concentrations were 1.1 ng m(-3) and 1.6 ng m(-3) at the Potsdam and Stockton sites, respectively. In general, vapor phase mercury concentrations increased with increasing ambient temperature at the Stockton site in 2000. These differences in values between 2000 and 2001 can be largely explained by distinct differences in the meteorological regimes that dominated in the different years.

Aerosols↗

PubMed2003

Reproductive health indicators for China's rural areas.

We report community-based development of reproductive health indicators for China's rural areas. To generate these indicators, we sequenced two participatory techniques known as nominal group process and Delphi survey methodology. Nominal group process entailed grassroots reproductive health workers' generating indicators, followed by refinement and prioritization of these indicators through a consensus-building Delphi process among nationally and internationally known reproductive health experts. Major criteria for the indicators were practicality, feasibility, and measurability within China's rural areas. We explain the importance of establishing these indicators for application in rural China and other developing countries as a complement to the World Health Organization's reproductive health indicators for global monitoring; present the identified indicators; and describe lessons learned from field testing in low-, middle-, and high-income counties of China's countryside.

Adult↗

PubMed2003

Spontaneous hair-cell renewal following gentamicin exposure in postnatal rat utricular explants.

We have established an in vitro model of long-time culture of 4-day-old rat utricular maculae to study aminoglycoside-induced vestibular hair-cell renewal in the mammalian inner ear. The explanted maculae were cultured for up to 28 days on the surface of a membrane insert system. In an initial series of experiments utricles were exposed to 1 mM of gentamicin for 48 h and then allowed to recover in unsupplemented medium or in medium supplemented with the anti-mitotic drug aphidicolin. In a parallel control series, explants were not exposed to gentamicin. Utricles were harvested at specified time points from the second through the 28th day in vitro. Whole-mount utricles were stained with phalloidin-fluorescein isothiocyanate and their stereociliary bundles visualized and counted. In a second experimental series 2'-bromo-5'deoxyuridine labeling was used to confirm the antimitotic efficacy of aphidicolin. Loss of hair-cell stereociliary bundles was nearly complete 3 days after exposure to gentamicin, with the density of stereociliary bundles only 3-4% of their original density. Renewal of hair-cell bundles was abundant (i.e. 15x increase) in cultures in unsupplemented medium, with a peak of stereociliary bundle renewal reached after 21 days in vitro. A limited amount of hair-cell renewal also occurred in the presence of the anti-mitotic drug, aphidicolin. These results suggest that spontaneous renewal of hair-cell stereociliary bundles following gentamicin damage in utricular explants predominantly follows a pathway that includes mitotic events, but that a small portion of the hair-cell stereociliary bundle renewal does not require mitotic activity.

Acoustic Maculae↗

PubMed2003

Expression and purification of Src I from sea anemone Sagartia rosea as a recombinant non-fusion protein.

The cDNA coding for an acidic actinoporin, Sagartia rosea cytolysin I (Src I), has been isolated, cloned into pGEM-T Easy Vector, and sequenced. The region encoding matured Src I was also cloned into prokaryotic expression vector pBV220 and expressed in Escherichia coli as a non-fusion protein in the form of inclusion body. Through washing and denaturation-renaturation step, the recombinant Src I was purified by Q Sepharose Fast Flow ion exchange chromatography and Phenyl Sepharose hydrophobic interaction chromatography. The two-step purification of Src I was effective, simple, and suitable for isolating large amount of high purity (above 95%) recombinant Src I.

Animals↗

PubMed2003

(Z,Z)-6,9-heneicosadien-11-one, labile sex pheromone of the whitemarked tussock moth, Orgyia leucostigma.

The whitemarked tussock moth (WMTM), Orgyia leucostigma (J. E. Smith), is a major pest of coniferous and deciduous trees in eastern Canada. Chemical identification of its sex pheromone depended primarily on GC-EAD and HPLC analysis, with confirmation of behavioral activity by wind tunnel and field tests. We identified (Z,Z)-6,9-heneicosadien-11-one (Z,Z-6,9-ket) at 4-5 ng/female as the only essential sex pheromone component. Also detected in female extracts were (Z)-6-heneicosen-11-one (Z6-ket) at 2.5 ng/female, (Z,E)-6,8-heneicosadien-11-one (Z,E-6.8-ket) at about 0.5 ng/female, and a trace amount of (Z,E)-6,9-heneicosadien-11-one. Traps containing as little as 1 microg of Z,Z-6,9-ket attracted males at low population levels, indicating it is a potent sex attractant. Traps baited with Z6-ket attracted few males, and in windtunnel bioassays it was at least 100-fold less attractive to males than Z,Z-6,9-ket. No improvement in trap catch occurred with the addition of Z6-ket in various binary mixtures with Z,Z-6,9-ket, including the female ratio, and a ternary mixture of Z,Z-6.9-ket, Z6-ket, and Z,E-6,8-ket in the 9:5:1 ratio detected in females was no better than Z,Z-6,9-ket alone. We attribute the presence of Z,E-6,8-ket and Z,E-6,9-ket in female extracts to the spontaneous and rapid stereospecific isomerization of Z,Z-6,9-ket at room temperature. Male flight began at sunset but peaked during the second half of the night.

Animals↗

PubMed2003

Tissue engineering of blood vessels with endothelial cells differentiated from mouse embryonic stem cells.

Endothelial cells (TEC3 cells) derived from mouse embryonic stem (ES) cells were used as seed cells to construct blood vessels. Tissue engineered blood vessels were made by seeding 8 106 smooth muscle cells (SMCs) obtained from rabbit arteries onto a sheet of nonwoven polyglycolic acid (PGA) fibers, which was used as a biodegradable polymer scaffold. After being cultured in DMEM medium for 7 days in vitro, SMCs grew well on the PGA fibers, and the cell-PGA sheet was then wrapped around a silicon tube, and implanted subcutaneously into nude mice. After 6~8 weeks, the silicon tube was replaced with another silicon tube in smaller diameter, and then the TEC3 cells (endothelial cells differentiated from mouse ES cells) were injected inside the engineered vessel tube as the test group. In the control group only culture medium was injected. Five days later, the engineered vessels were harvested for gross observation, histological and immunohistochemical analysis. The preliminary results demonstrated that the SMC-PGA construct could form a tubular structure in 6~8 weeks and PGA fibers were completely degraded. Histological and immunohistochemical analysis of the newly formed tissue revealed a typical blood vessel structure, including a lining of endothelial cells (ECs) on the lumimal surface and the presence of SMC and collagen in the wall. No EC lining was found in the tubes of control group. Therefore, the ECs differentiated from mouse ES cells can serve as seed cells for endothelium lining in tissue engineered blood vessels.

Animals↗

PubMed2003

Roles of OsCKI1, a rice casein kinase I, in root development and plant hormone sensitivity.

Casein kinases are critical in cell division and differentiation across species. A rice cDNA fragment encoding a putative casein kinase I (CKI) was identified via cDNA macroarray under brassinosteroid (BR) treatment, and a 1939-bp full-length cDNA, OsCKI1, was isolated and found to encode a putative 463-aa protein. RT-PCR and Northern blot analysis indicated that OsCKI1 was constitutively expressed in various rice tissues and upregulated by treatments with BR and abscisic acid (ABA). Enzymatic assay of recombinant OsCKI1 proteins expressed in Escherichia coli showed that the protein was capable of phosphorylating casein. The physiological roles of OsCKI1 were studied through antisense transgenic approaches, and homozygous transgenic plants showed abnormal root development, including fewer lateral and adventitious roots, and shortened primary roots as a result of reduced cell elongation. Treatment of wild-type plants with CKI-7, a specific inhibitor of CKI, also confirmed these functions of OsCKI1. Interestingly, in transgenic and CKI-7-treated plants, exogenously supplied IAA could restore normal root development, and measurement of free IAA content in CKI-deficient primary and adventitious roots revealed altered auxin content, indicating that OsCKI1 is involved in auxin metabolism or that it may affect auxin levels. Transgenic plants were less sensitive than control plants to ABA or BR treatment during germination, suggesting that OsCKI1 may be involved in various hormone-signaling pathways. OsCKI1-GFP fusion studies revealed the localization of OsCKI1 to the nucleus, suggesting a possible involvement in regulation of gene expression. In OsCKI1-deficient plants, differential gene expression was investigated using cDNA chip technology, and results indicated that genes related to signal transduction and hormone metabolism were indeed with altered expression.

Amino Acid Sequence↗

PubMed2003

Iron toxicity in organotypic cultures of hippocampal slices: role of reactive oxygen species.

Free iron has been assumed to potentiate oxygen toxicity by generating reactive oxygen species (ROS) via the iron-catalyzed Haber-Weiss reaction, leading to oxidative stress. ROS-mediated iron cytotoxicity may trigger apoptotic cell death. In the present study, we used iron treatment of organotypic cultures of hippocampal slices to study potential mechanisms involved in iron-induced neuronal damage. Exposure of mature hippocampal slices to ferrous sulfate resulted in concentration- and time-dependent cell death. After iron treatment, markers of ROS formation and lipid peroxidation, i.e. intensity of dichlorofluorescein (DCF) fluorescence and levels of thiobarbiturate reactive substances (TBARS), were significantly increased. Levels of cytochrome c were increased while levels of pro-caspase-9 and pro-caspase-3 were decreased in cytosolic fractions of iron-treated hippocampal slice cultures. Treatment of cultured slices with a synthetic catalytic ROS scavenger, EUK-134, provided between 50 and 70% protection against various parameters of cell damage and markers of oxidative stress. In addition, inhibition of caspase-3 activity by Ac-DEVDcho partially protected cells from iron toxicity. The combination of EUK-134 and Ac-DEVDcho resulted in an almost complete blockade of iron-induced damage. These results indicate that iron elicits cellular damage predominantly by oxidative stress, and that ROS-mediated iron toxicity may involve cytochrome c- and caspase-3-dependent apoptotic pathways.

Animals↗

PubMed2003

The calcimimetic AMG 073 reduces parathyroid hormone and calcium x phosphorus in secondary hyperparathyroidism.

BACKGROUND: A need exists for a therapy that lowers parathyroid hormone (PTH) without increasing calcium x phosphorus in patients with secondary hyperparathyroidism. The calcimimetic AMG 073 increases the sensitivity of the parathyroid calcium-sensing receptor to extracellular calcium, thereby reducing PTH secretion. Consequently, AMG 073 may provide a novel therapy for secondary hyperparathyroidism. METHODS: Seventy-eight hemodialysis patients with secondary hyperparathyroidism were enrolled into this 18-week, double-blind, randomized, placebo-controlled, dose titration study. Daily oral AMG 073 doses were administered to determine the effect on PTH, serum calcium, phosphorus, and calcium x phosphorus. RESULTS: The mean baseline PTH was similar in patients administered AMG 073 or placebo (632 +/- 280.1 pg/mL vs. 637 +/- 455.9 pg/mL, respectively). PTH decreased by 26.0% in the AMG 073-treated group, compared with an increase of 22.0% in the placebo group (P < 0.001). A greater proportion in the AMG 073 group (38%) had a decrease in PTH >or=30%, compared with the placebo group (8%) (P = 0.001). Decreases in PTH were independent of baseline vitamin D usage. Patients receiving AMG 073 had an 11.9% decrease in calcium x phosphorus compared with a 10.9% increase in the placebo group (P < 0.001). Use of vitamin D sterols, as well as both calcium and noncalcium-containing phosphate binders. were similar between treatment groups. Administration of AMG 073 was safe and well tolerated in this 18-week study. CONCLUSIONS: The calcimimetic AMG 073 decreases both PTH and calcium x phosphorus levels in hemodialysis patients with secondary hyperparathyroidism.

Adult↗

PubMed2003

Extensive neoplastic cardiac infiltration in a patient with acute myelogenous leukemia: role of echocardiography.

We present the case of a 34-year-old man with a history of relapsed acute myelogenous leukemia with extensive metastatic infiltration of the endomyocardium. Transesophageal echocardiography revealed masses within all the cardiac chambers and associated vascular structures. Biopsy of the superior vena cava mass had the histological features of a granulocytic sarcoma (GS, chloroma). Massive involvement of the heart with GS is very rare, and only a few reports have been published in the literature.

Adult↗

PubMed2003

Cytokine regulation of IL-13Ralpha2 and IL-13Ralpha1 in vivo and in vitro.

BACKGROUND: IL-13 signals via a high-affinity receptor that includes IL-4Ralpha and IL-13Ralpha1 and binds to the decoy receptor IL-13Ralpha2. The processes that regulate the expression of these receptor subunits, however, are poorly defined. OBJECTIVE: These studies were designed to define the regulation of IL-13R components by T(H)2 and T(H)1 cytokines in vivo and in vitro. METHODS: Northern analysis, in situ hybridization, RT-PCR analysis, and immunoprecipitation were used to define the expression of IL-13Ralpha1 and IL-13Ralpha2 in lungs from lung targeted overexpression mice and lung fragments and cells in culture. RESULTS: IL-13Ralpha2 and IL-13Ralpha1 mRNA were detected at modest levels in lungs from control mice. In contrast, transgenic IL-13 caused a marked increase in IL-13Ralpha2 and IL-13Ralpha1 mRNA; this was most prominent in airway epithelial cells and macrophages. The effects of IL-13 on IL-13Ralpha2 were associated with comparable increases in protein production and were mediated by a blood leukocyte-independent and IL-4Ralpha-dependent mechanism. IL-13 stimulation of IL-13Ralpha1 was mediated via a blood leukocyte-dependent and partially IL-4Ralpha-dependent pathway. These effects were not specific for IL-13, because transgenic IL-4, IL-10, and IFN-gamma also stimulated IL-13Ralpha2 mRNA accumulation while stimulating-not altering and inhibiting-IL-13Ralpha1 mRNA accumulation, respectively. These regulatory events were mediated, at least in part, by direct effects of these cytokines, because IL-13, IL-4, and IFN-gamma had similar effects on IL-13Ralpha2 and/or IL-13Ralpha1 in epithelial cells and macrophages in in vitro culture. CONCLUSION: IL-13Ralpha2 and IL-13Ralpha1 are highly regulated in vivo and in vitro. These regulatory events might control IL-13 responses at sites of inflammation.

Animals↗