Radiotherapy dose and survival outcomes in human papillomavirus positive oropharyngeal cancer.

OBJECTIVE: To evaluate the effect of definitive radiotherapy dose on survival in patients with human papillomavirus positive oropharyngeal carcinoma. METHODS: Human papillomavirus positive oropharyngeal carcinoma patients staged T1-3 and N0-2c, who received definitive radiotherapy (fraction sizes of 180 cGy to less than 220 cGy), were identified from the National Cancer Database 2010-2014 and stratified by radiation dose (50 Gy to less than 66 Gy, or 66 Gy or more). RESULTS: A total of 2173 patients were included, of whom 124 (6 per cent) received a radiation dose of 50 Gy to less than 66 Gy. With a median follow up of 33.8 months, patients had a 3-year overall survival rate of 88.6 per cent (95 per cent confidence interval = 87.1-90.1 per cent). On multivariate Cox analysis, a radiotherapy dose of 50 Gy to less than 66 Gy (hazard ratio = 0.95, 95 per cent confidence interval = 0.52-1.74, p = 0.86) was not a predictor of increased mortality risk. CONCLUSION: Human papillomavirus positive oropharyngeal carcinoma patients had excellent outcomes with definitive radiotherapy doses of 50 Gy to less than 66 Gy. These results further support patients enrolling into clinical trials for radiation dose de-escalation.

Periodontal disease severity is associated with micronutrient intake.

BACKGROUND: This study aimed to examine if specific micronutrients were associated with periodontal disease using data from the US National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014. METHODS: Participants who were aged 30 years or more and received complete periodontal examinations were included. Regression analyses were performed to determine associations of variables of interest with periodontal disease. RESULTS: Data of 6415 NHANES participants were included in the analysis. Multivariable analysis revealed that less intake of vitamin A (adjusted odds ratio (aOR) = 1.784), vitamin B1 (aOR = 1.334), vitamin C (aOR = 1.401), vitamin E (aOR = 1.576), iron (aOR = 1.234), folate (aOR = 1.254) and phosphorus (aOR = 1.280) was associated with increased severity of periodontal disease. Compared with the highest level of vitamin D intake, the second highest level of vitamin D intake was associated with lower severity of periodontal disease (aOR = 0.727). CONCLUSIONS: Insufficient intake of vitamin A, B1, C and E, iron, folate and phosphorus was significantly associated with severity of periodontal disease. Results of the present study suggest that the above micronutrients may be increased in the diet or taken as dietary supplements in order to reduce severity of periodontal disease.

Cryopreservation of gemmae of Marchantia polymorpha L. (Marchantiophyta, Marchantiaceae) without prior pretreatment.

BACKGROUND: Successful cryopreservation of gametophytic material of bryophytes requires pretreatment with sucrose or abscisic acid. Compared to gametophyte materials, spore and gemmae cryopreservation may be more efficient, simple and stable systems for storing large amounts of genetic diversity of bryophytes within a small space. However, there has still been no attempt at cryopreserving bryophyte gemmae. OBJECTIVE: The aim of this study is to determine whether bryophyte gemmae with differing levels of desiccation tolerance could survive and germinate after cryopreservation without prior encapsulation and pretreatment. MATERIALS AND METHODS: Gemmae of Marchantia polymorpha L. were dried with silica gel for different times and then rapidly cooled in liquid nitrogen. RESULTS: The germination level of fresh gemmae was 95 % After 3 h predrying and 1 d in LN, germination was 68 % and was still up to 59 % after storage for 75 days. CONCLUSION: We conclude that the natural desiccation tolerance of bryophyte gemmae permits cryopreservation without prior pretreatment other than drying.

Corticosterone mediates stress-related increased intestinal permeability in a region-specific manner.

BACKGROUND: Chronic psychological stress (CPS) is associated with increased intestinal epithelial permeability and visceral hyperalgesia. It is unknown whether corticosterone (CORT) plays a role in mediating alterations of epithelial permeability in response to CPS. METHODS: Male rats were subjected to 1-h water avoidance (WA) stress or subcutaneous CORT injection daily for 10 consecutive days in the presence or absence of corticoid receptor antagonist RU-486. The visceromotor response (VMR) to colorectal distension (CRD) was measured. The in situ single-pass intestinal perfusion was used to measure intestinal permeability in jejunum and colon simultaneously. KEY RESULTS: We observed significant decreases in the levels of glucocorticoid receptor (GR) and tight junction proteins in the colon, but not the jejunum in stressed rats. These changes were largely reproduced by serial CORT injections in control rats and were significantly reversed by RU-486. Stressed and CORT-injected rats demonstrated a threefold increase in permeability for PEG-400 (MW) in colon, but not jejunum and significant increase in VMR to CRD, which was significantly reversed by RU-486. In addition, no differences in permeability to PEG-4000 and PEG-35 000 were detected between control and WA groups. CONCLUSIONS & INFERENCES: Our findings indicate that CPS was associated with region-specific decrease in epithelial tight junction protein levels in the colon, increased colon epithelial permeability to low molecular weight macromolecules which were largely reproduced by CORT treatment in control rats and prevented by RU-486. These observations implicate a novel, region-specific role for CORT as a mediator of CPS-induced increased permeability to macromolecules across the colon epithelium.

Effect of aging on the morphology of bitumen by atomic force microscopy.

Effect of aging on the morphology of bitumen was investigated. Two bitumens were aged according to the thin film oven test (TFOT), pressure aging vessel (PAV) test and ultraviolet (UV) radiation, respectively. The morphology of the binders before and after aging was characterized by atomic force microscopy. The physical properties and chemical compositions of the binders were also measured. The results showed that aging affected the bitumen morphology significantly. Aging increased the overall surface stiffness of the bitumen and made the bitumen surface more solid-like. The extent of these changes was dependent on aging conditions. TFOT decreased the contrast between the dispersed domains and the matrix, which contributed to the single-phase trend of the binders. The effect of PAV aging on morphology of the binders was dependent on the base bitumen. In one case, it further accelerated the single-phase trend of bitumen in comparison with that after TFOT. In the other case, it caused the phase separation of bitumen. In both cases, PAV aging increased the surface roughness of the binders obviously. As a result of UV aging, the contrast between the matrix phase and dispersed phase was increased due to the difference in sensitivity to UV radiation of the bitumen molecules, which caused or further promoted the phase separation in the binders. Regardless of the aging procedure carried out, a strong correlation was observed between the changes in morphology and physical properties as well as chemical compositions of the binders before and after aging.

Enzyme replacement therapy for mucopolysaccharidosis VI (Maroteaux-Lamy syndrome): experience in Hong Kong.

Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome) is a very rare inherited lysosomal storage disease. We evaluated the efficacy and safety of weekly infusions of recombinant human arylsulfatase B as enzyme replacement therapy for two patients in whom this condition was advanced. The primary outcome variables were the distance walked in a 6-minute walk test, forced vital capacity, and ejection fraction. The secondary outcome variables were the number of stairs climbed in a 3-minute stair climbing test, joint mobility, urinary glycosaminoglycan excretion, auto-continuous positive airway pressure study and liver size. After 24 weeks of treatment, patient A walked 40 m (36%) and patient B walked 66 m (58%) more in the walk test than at baseline. After 48 weeks, in patient A the corresponding improvements were 142 m (129%) in the walk test and 33 stairs (60%) in the 3-minute stair climbing test, and in patient B the respective improvements were 198 m (174%) and 77 stairs (140%). There was a significant decline in urinary glycosaminoglycan excretion and improvement in range of motion of joints in both patients. The auto-continuous positive airway pressure study revealed improvements in patient A, while other efficacy variables remained static. There were no drug-related adverse events or allergic reactions reported during and after the infusions of recombinant human arylsulfatase B. Recombinant human arylsulfatase B significantly improves endurance and reduces urinary glycosaminoglycan excretion. The drug is generally safe and well tolerated.

Six placenta permeability-related genes: molecular characterization and expression analysis in pigs.

The nutrient transportation ability of placenta depends on placental size, vascular density and permeability. Regulation of angiogenesis in the placenta is critical for successful gestation. Placenta vascularity exhibits disparity in different gestation stages and different pig breeds. To investigate the expression of genes related to permeability in the porcine placenta of different gestation stages and breeds, molecular cloning and gene expression analysis of six porcine genes, vascular endothelial growth factor (VEGF), VEGF-R1, VEGF-R2, endothelial nitric oxide synthase (eNOS), vascular endothelial cadherin (CDH5) and ß-arrestin2 (Arrb2), were performed in this study. The results demonstrated that from gestation day 33 to day 90, Landrace exhibited significant increase (P < 0.05) in placental VEGF and Arrb2 mRNA expression. Moreover, expression levels of VEGF, VEGF-R1, VEGF-R2 and eNOS mRNA were higher (P < 0.01) in the placenta of Erhualian than those in Landrace on day 90 of gestation. In contrast, CDH5 placental mRNA expression level exhibited significant decrease (P < 0.05) from day 33 to day 90 gestation in Landrace. Erhualian placental CDH5 and Arrb2 expression levels were significantly lower (P < 0.01) than those in Landrace conceptuses on day 90 of gestation. Our study offered new data on the expression of genes in VEGF signal transduction pathway in porcine placenta.

Ergonomic study of a vertical rope-pulling task from a scaffolding.

The purpose of this study is to explore and assess manual material handling problems involving a vertical rope-pulling task from a scaffold (VRPS). Twenty-five young male Chinese subjects were recruited to participate in this study. The psychophysical method was used to investigate the effects of the rope material (nylon and hemp), rope diameter (6/8'' and 4/8''), object size (bucket diameter 28 cm and 36 cm), operating with and without gloves on the maximum acceptable rope-pulling weight (MAWR), rating of perceived exertion (RPE) and heart rate, respectively. The results showed that the maximum acceptable rope-pulling weights were significantly affected by the rope material, rope diameter, object size and wearing or not wearing gloves. The MAWR for the hemp rope, coarse rope, small object size and without gloves was significantly greater than that for the nylon rope, fine rope, large object size and with gloves, respectively. However, the effect of the rope material, rope diameter, object size and with and without gloves on heart rate was not significant. The mean RPE response was significantly influenced by the rope material, object size and wearing or not wearing gloves. The most stressed body parts were the arms, fingers and wrists. The interaction effect between the rope material and wearing or not wearing gloves was significant. Generally, the VRPS for workers using hemp rope without gloves or using nylon rope without gloves was better than that for the other combinations.

Polycyclic aromatic hydrocarbons in leaf cuticles and inner tissues of six species of trees in urban Beijing.

Leaf samples of six tree species were collected along urban roadsides and a campus site in Beijing for measurement of polycyclic aromatic hydrocarbons (PAHs). PAHs in leaves were attributed to two fractions, leaf cuticles and inner leaf tissues, using sequential extraction. Total concentrations of 16 PAHs in the cuticles and the inner tissues were 69.3+/-64.6 microg g(-1) (d.w.) and 1.07+/-0.2 microg g(-1) (d.w.) at roadside and 57.5+/-52.6 microg g(-1) and 0.716+/-0.2 microg g(-1) on campus, respectively. The lipid-normalized inner tissue PAHs varied from 5.8 microg g(-1) to 15.0 microg g(-1). Similarities in PAH spectra between leaf cuticles and airborne particles and between the inner tissues and gaseous phase imply that airborne particulates and gaseous PAHs are likely the sources of PAHs for cuticles and the inner tissues, respectively. Difficulty in migration of heavier PAHs into inner tissues could be another reason.

Particle size distributions of polycyclic aromatic hydrocarbons in rural and urban atmosphere of Tianjin, China.

The size distributions of 16 polycyclic aromatic hydrocarbons (PAHs) and particle mass less than 10 microm in aerodynamic diameter (Dp) were measured using a nine-stage low-volume cascade impactor at rural and urban sites in Tianjin, China in the winter of 2003-2004. The particles exhibited the trimodal distribution with the major peaks occurring at 0.43-2.1 and 9.0-10.0 microm for both urban and rural sites. The concentrations of the total PAH (sum of 16 PAH compound) at rural site were generally less than those of urban site. Mean fraction of 76.5% and 63.9% of the total PAH were associated with particles of 0.43-2.1 microm at rural and urban sites, respectively. Precipitation, temperature, wind speed and direction were the important meteorological factors influencing the concentration of PAHs in rural and urban sites. The distributions of PAHs concentration with respect to particle size were similar for rural and urban samples. The PAHs concentrations at the height of 40 m were higher than both of 20 and 60 m at urban site, but the mass median diameter (MMD) of total PAH increased with the increasing height. The mid-high molecular weight (278 >or= MW >or= 202) PAHs were mainly associated with fine particles (Dp or=MW >or=178) PAHs were distributed in both of fine and coarse particle. The fraction of PAHs associated with coarse particles (Dp>2.1 microm) decreased with increasing molecular weight. The relatively consistent distribution of PAHs seemed to indicate the similar combustion source of PAHs at both of rural and urban sites. The fine differences of concentration and distribution of PAHs at different levels at urban site suggested that the different source and transportation path of particulate PAHs.

Polycyclic aromatic hydrocarbons in dustfall in Tianjin, China.

Atmospheric dustfall samples from 23 locations in Tianjin, China, were collected and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs) classified by the Environmental Protection Agency as priority pollutants from March 2002 to March 2003. SigmaPAH16 (sum of 16 PAH compounds) concentrations in the dustfall collected during heating season ranged from 2.5 to 85.5 mug/g, while that during the non-heating season varied from 1.0 to 48.2 microg/g dry weight. The dominant components in the heating season included naphthalene, phenanthrene, fluoranthene, and chrysene, while naphthalene, fluorene, phenanthrene, and fluoranthene were dominant during the non-heating season. Compared with the non-heating season, the heating season was characterized by a higher fraction of high-molecular-weight PAHs with four to six rings with exception of the samples from the east industrial area. The east industrial area had more significant correlations between individual PAH compounds, and more discrete triangular components of three-, four-, five- and six-ring PAHs. No significant correlations were observed between the PAHs concentrations and total organic carbon (TOC) in the dustfall samples. The deposition fluxes of sigmaPAH15 (sum of 15 PAHs except naphthalene), sigmaPAH6 (sum of 6 carcinogenic PAHs recommended by IARC) and benzo[a]pyrene (BaP) from atmospheric deposition to the whole area were estimated as 1911, 196, and 53 microg/m2/year, respectively. The deposition rates for PAH compounds in the east industrial area were higher than those in the urban and rural areas. Furthermore, the deposition contribution of PAHs during domestic heating season in winter was not significant relative to the annual inputs.

Contamination of rivers in Tianjin, China by polycyclic aromatic hydrocarbons.

Tianjin urban/industrial complex is highly polluted by some persistent organic pollutants. In this study, the levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were tested in sediment, water, and suspended particulate matter (SPM) samples in 10 rivers in Tianjin. The total concentration of 16 PAHs varied from 0.787 to 1943 microg/g dry weight in sediment, from 45.81 to 1272 ng/L in water, and from 0.938 to 64.2 microg/g dry weight in SPM. The levels of PAHs in these media are high in comparison with values reported from other river and marine systems. Variability of total concentrations of PAHs in sediment, water, and SPM from nine different rivers is consistent with each other. No obvious trends of total PAHs concentration variations were found between upstream and downstream sediment, water, and SPM samples for most rivers, which indicate local inputs and disturbances along these rivers. The spatial distributions of three-phase PAHs are very similar to each other, and they are also similar to those found in topsoil. However, their chemical profiles are significantly different from that of topsoil. The change of profiles is consistent with the different aqueous transport capability of 16 PAHs. Low molecular weight PAHs predomination suggests a relatively recent local source and coal combustion source of PAHs in the study area.

Psychophysical determination of load carrying capacity for a 1-h work period by Chinese males.

This study used the psychophysical approach to examine the effects of container width, the presence or absence of container handles, and different load-carrying frequencies and distances on the maximum acceptable weight carried and the resulting response (heart rate and rating of perceived exertion) by well-conditioned males for a 1-h work period. After training, 12 male subjects performed a load-carrying task at knuckle height. Each subject performed 30 different carrying combinations. The conditions examined were container width, from 15.2 to 55.9 cm; carrying frequency, from 1 carry to 5 carries/min; and carrying distance from 1 to 6 m. The results were compared with prior studies and led to the following conclusions: (1) the use of container handles leads to the subjects carrying a significantly higher maximum acceptable weight than when containers do not have handles, which differs from the results of a previous study by Morrissey and Liou; (2) there were significant reductions in the maximum acceptable carrying weight with increases in container width, frequency and distance; (3) the presence or absence of container handles, different frequencies and load-carrying distances had significant effects on heart rate, although the effect of container width was not significant. In addition, the various frequencies and distances for load carrying had significant interaction effects on heart rate; (4) the effects of various frequencies and load-carrying distances on the rating of perceived exertion were statistically significant. The most stressed body parts were the wrists and arms.

E-cadherin expression and PSA secretion in human prostate epithelial cells.

Prostate-specific antigen (PSA) is the most widely used marker for the diagnosis of prostate cancer and is an independent predictor of prostatic capsular invasion. A number of studies have identified E-cadherin, a cell adhesion protein, as a potential invasion suppressor which is decreased in prostate adenocarcinoma. Our goal in the present study was to evaluate E-cadherin expression in primary cultures and determine the relationship between E-cadherin expression and PSA secretion in both primary cultures and the prostate tumor cell line, LNCaP. Immunohistochemical studies and Western blot analysis confirmed greater expression of E-cadherin in normal epithelial cells than tumor-derived prostate cells. This is the first report that the incubation of normal prostate epithelial cells with E-cadherin antibody increases the amount of PSA detected in the media of normal cells as well as in LNCaP. Since E-cadherin may function as an invasion suppressor, an understanding of the decreased expression of this adhesion factor and the impact on PSA secretion may aid in understanding epithelial tumorigenesis.

Coronary smooth muscle differentiation from proepicardial cells requires rhoA-mediated actin reorganization and p160 rho-kinase activity.

We recently reported that the first detectable expression of SMC-specific proteins during coronary smooth muscle cell (CoSMC) differentiation from isolated proepicardial cells was restricted to cells undergoing epithelial-to-mesenchymal transformation (EMT). The objectives of this study were to examine more closely the relation between actin cytoskeletal rearrangements and serum response factor (SRF)-dependent transcription, and to specifically test whether rhoA-GTPase signaling is required for CoSMC differentiation. We report here that PDGF-BB stimulates EMT and promotes SRF-dependent expression of SMC marker genes calponin, SM22alpha, and SMgamma(actin) (SMgammaA) in proepicardial cells. C3 exoenzyme or rhoGDI, inhibitors of rhoA signaling, blocked PDGF-BB-induced EMT, prevented actin reorganization into stress fibers, and inhibited CoSMC differentiation. Incubation with the selective p160 rho-kinase (p160RhoK) inhibitor Y27632 (RKI) blocked EMT, prevented the appearance of calponin and SMgammaA-positive cells, and abolished expression and nuclear localization of SRF. To test the role of RhoK signaling for CoSMC differentiation in vivo, quail proepicardial organs (PEOs) were pretreated with RKI or vehicle and then grafted into age-matched host chick embryos to produce a chimeric epicardium. The ability of grafted cells to participate in coronary vessel formation was monitored by staining with antibodies for quail cell nuclear antigen and SMC marker proteins. Proepicardial cells pretreated with RKI failed to form CoSMCs in vivo. Time course studies traced this deficiency to a failure of epicardial-derived mesenchymal cells to migrate into or survive within the myocardium. In summary, these data point to important roles for rhoA-RhoK signaling in molecular pathways controlling cytoskeletal reorganization, SRF-dependent transcription, and cell survival that are required to produce CoSMCs from proepicardial cells.

Involvement of mitogen-activated protein kinase in hippocampal long-term potentiation.

Mitogen-activated protein kinase (MAPK) cascade classically is thought to be involved in cellular transformation, including proliferation and differentiation. Recent behavioral studies suggest that MAPK may also have a role in learning and memory. Long-term potentiation (LTP), a candidate mechanism for learning and memory, has at least two distinct temporal phases: an early phase (E-LTP) which lasts for 1-2 h and a late phase (L-LTP) which can persist >/=3 h. Here, we report that PD 098059, a selective inhibitor of MAPK cascade, attenuates L-LTP induced by bath application of forskolin without affecting basal synaptic transmission. This effect was mimicked by direct injection of animals with MAPK antisense oligonucleotide into the hippocampal CA1 region. MAPK activity measured by using a synthetic peptide corresponding to the sequence surrounding the major site of phosphorylation of the myelin-basic protein by MAPK was enhanced by forskolin. The same antisense treatment also completely inhibited the increased MAPK activity. These results demonstrate an involvement of MAPK in the induction of L-LTP in the hippocampal CA1 neurons.

Dynamic changes in the characteristics of cationic lipidic vectors after exposure to mouse serum: implications for intravenous lipofection.

Intravenous gene delivery via cationic lipidic vectors gives systemic gene expression particularly in the lung. In order to understand the mechanism of intravenous lipofection, a systematic study was performed to investigate the interactions of lipidic vectors with mouse serum emphasizing how serum affects the biophysical and biological properties of vectors of different lipid compositions. Results from this study showed that lipidic vectors underwent dynamic changes in their characteristics after exposure to serum. Addition of lipidic vectors into serum resulted in an immediate aggregation of vectors. Prolonged incubation of lipidic vectors with serum led to vector disintegration as shown in turbidity study, sucrose-gradient centrifugation analysis and fluorescence resonance energy transfer (FRET) study. Vector disintegration was associated with DNA release and degradation as shown in EtBr intercalation assay and DNA digestion study. Serum-induced disintegration of vectors is a general phenomenon for all cationic lipidic vectors tested in this study. Yet, vectors of different lipid compositions vary greatly in the rate of disintegration. There is an inverse correlation between the disintegration rate of lipidic vectors and their in vivo transfection efficiency. Vectors with a rapid rate of disintegration such as those containing dioleoyl-phosphatidylethanolamine (DOPE) poorly stayed in the lung and were barely active in transfecting cells. In contrast, cholesterol-containing vectors that had a rapid aggregation and a slow disintegration were highly efficient in transfecting cells in vivo. The results of this study explain why cationic lipidic vectors of different lipid compositions have a dramatic difference in their in vivo transfection efficiency. These results also suggest that the study of the interactions of lipidic vectors with serum may serve as a predictive model for the in vivo efficiency of a lipidic vector. Further study of the numerous interactions of lipidic vectors with serum might lead to the development of a vector which can deliver a gene to target cells in a tissue-specific manner.

Psychophysically determined infrequent lifting capacity of Chinese participants.

The aim of this study was to investigate the psychophysical infrequent lifting capacity (maximum acceptable weight of lift, MAWL) for a Chinese population. A nested-factorial experimental design with a participant factor nested within gender was employed. Forty-one Chinese participants (29 males, 12 females) participated in the study. Two frequencies (one lift every 8 h and one lift every 5 min) and six lifting heights (floor to knuckle, floor to shoulder, floor to reach, knuckle to shoulder, knuckle to reach, shoulder to reach) were evaluated. The results are compared with prior studies and they lead to the following conclusions. (1) The MAWLs were significantly affected by both the lifting frequency and lifting height. For lifting frequency, the MAWLs decreased markedly by nearly 30% from one lift every 8 h to one lift every 5 min. For lifting height, the MAWLs of the F-K was the greatest of all six lifting heights, followed by F-S, K-S, F-R, K-R and S-R was the smallest. (2) The MAWLs for Chinese females are significantly lower, but proportionately similar, to the MAWLs for Chinese males. (3) The Chinese participants had smaller capacities compared with the Occidental participants, and the rate of decrease in MAWL for the Chinese participants was much sharper than that of Occidental participants. (4) The MAWL of Chinese females was about 54-58% of the Chinese males, it is somewhat lower than those of 60-70% of the Occidental participants.

Crystallization and preliminary crystallographic analysis of the Escherichia coli tyrosine aminotransferase.

Tyrosine aminotransferase catalyzes transamination for both dicarboxylic and aromatic amino-acid substrates. The substrate-free Escherichia coli tyrosine aminotransferase (eTAT) bound with the cofactor pyridoxal 5'-phosphate (PLP) was crystallized in the trigonal space group P3(2). A low-resolution crystal structure of eTAT was determined by molecular-replacement methods. The overall folding of eTAT resembles that of the aspartate aminotransferases, with the two identical subunits forming a dimer in which each monomer binds a PLP molecule via a covalent bond linked to the epsilon-NH(2) group of Lys258. Comparison of the structure of eTAT with those of the open, half-open or closed form of chicken or E. coli aspartate aminotransferases shows the eTAT structure to be in the open conformation.

Effect of immune response on gene transfer to the lung via systemic administration of cationic lipidic vectors.

Cationic lipid-mediated intravenous gene delivery shows promise in treating pulmonary diseases including lung tumor metastases, pulmonary hypertension, and acute respiratory distress syndrome. Nevertheless, clinical applications of cationic lipidic vectors via intravenous administration are limited by their transient gene expression. In addition, repeated dosing is not effective at frequent intervals. In an effort to elucidate the mechanism of gene inactivation, we report in this study that cationic lipid-protamine-DNA (LPD) complexes, but not each component alone, can induce a high level of cytokine production, including interferon-gamma and tumor necrosis factor-alpha. Furthermore, we demonstrate that LPD administration triggers apoptosis in the lung, a phenomenon that may be mediated in part by the two cytokines. Treatment of mice with antibodies against the two cytokines prolongs the duration of gene expression and also improves lung transfection on a second administration of LPD. Although the mechanism underlying LPD-induced cytokine production is unclear, methylation of the DNA significantly decreased the level of both interferon-gamma and tumor necrosis factor-alpha, suggesting that unmethylated CpG sequences in plasmid DNA play an important role. These data suggest that decreasing the CpG-mediated immune response while not affecting gene expression may be a useful therapeutic strategy to improve cationic lipid-mediated intravenous gene delivery to the lung.