Dual peptides-modified cationic liposomes for enhanced Lung cancer gene therapy by a gap junction regulating strategy.

BACKGROUND: Gene therapy for lung cancer has emerged as a novel tumor-combating strategy for its superior tumor specificity, low systematical toxicity and huge clinical translation potential. Especially, the applications of microRNA shed led on effective tumor ablation by directly interfering with the crucial gene expression, making it one of the most promising gene therapy agents. However, for lung cancer therapy, the microRNA treatment confronted three bottlenecks, the poor tumor tissue penetration effect, the insufficient lung drug accumulation and unsatisfied gene transfection efficiency. To address these issues, an inhalable RGD-TAT dual peptides-modified cationic liposomes loaded with microRNA miR-34a and gap junction (GJ) regulation agent all-trans retinoic acid (ATRA) was proposed, which was further engineered into dry powder inhalers (DPIs). RESULTS: Equipped with a rough particle surface and appropriate aerodynamic size, the proposed RGD-TAT-CLPs/ARTA@miR-34a DPIs were expected to deposit into the deep lung and reach lung tumor lesions guided by targeting peptide RGD. Assisted by cellular transmembrane peptides TAT, the RGD-TAT-CLPs/ARTA@miR-34a was proven to be effectively internalized by cancer cells, enhancing gene transfection efficiency. Then, the GJ between tumor cells was upregulated by ARTA, facilitating the intercellular transport of miR-34a and boosting the gene expression in the deep tumor. CONCLUSION: Overall, the proposed RGD-TAT-CLPs/ARTA@miR-34a DPIs could enhance tumor tissue penetration, elevate lung drug accumulation and boost gene transfection efficiency, breaking the three bottlenecks to enhancing tumor elimination in vitro and in vivo. We believe that the proposed RGD-TAT-CLPs/ARTA@miR-34a DPIs could serve as a promising pulmonary gene delivery platform for multiple lung local disease treatments.

Repair of extrahepatic bile duct defect using a collagen patch in a Swine model.

Extrahepatic bile duct (EBD) injury can happen during surgery. To repair a defect of the EBD and prevent postoperative biliary complications, a collagen membrane was designed. The collagen material was porous, biocompatible, and degradable and could maintain its shape in bile soaking for about 4 weeks. The goal was to induce rapid bile duct tissue regeneration. Twenty Chinese experimental hybrid pigs were used in this study and divided into a patch group and a control group. A spindle-shaped defect (20 mm × 6 mm) was made in the anterior wall of the lower EBD in the swine model, and then the defect was reconstructed using a collagen patch with a drainage tube and wrapped with greater omentum. Ultrasound was performed at 2, 4, 8, and 12 weeks postoperatively. Liver function tests and white blood cell count (WBC) were measured. Hematoxylin-eosin staining, cytokeratin 7 immunohistochemical staining, and Van Gieson's staining of EBD were used. The diameter and thickness of the EBD at the graft site were measured. There was no significant difference in liver function tests or WBC in the patch group compared with the control group. No evidence of leakage or stricture was observed, but some pigs developed biliary sludge or stone at 4 and 8 weeks. The drainage tube was lost within 12 weeks. The neo-EBD could withstand normal biliary pressure 2 weeks after surgery. Histological study showed the accessory glands and epithelial cells gradually regenerated at graft sites from 4 weeks, with increasing vessel infiltration and decreasing inflammation. The collagen fibers became regular with full coverage of epithelial cells. The statistical analysis of diameter and thickness showed no stricture formation at the graft site, but the EBD wall was slightly thicker than in the normal bile duct due to collagen fiber deposition. The structure of the neo-EBD was similar to that of the normal EBD. The collagen membrane patch associated with a drainage tube and wrapped with greater omentum effectively induced the regeneration of the EBD defect within 12 weeks.

Revealing the Development Patterns of the Mandibular Glands of Apis mellifera carnica Based on Transcriptomics and Morphology.

The mandibular gland in worker bees synthesizes and secretes the organic acids present in royal jelly, and its development directly affects yield and quality. Therefore, we aimed to analyze the differences in morphology and gene expression in the mandibular glands of Apis mellifera carnica worker bees of different ages (3, 6, 9, 12, and 16 d). We dissected their mandibular glands and performed morphological and transcriptomic analyses to investigate the development of the mandibular gland and the molecular regulatory mechanisms involved in royal jelly secretion. Microscopy revealed that mandibular gland development is likely completed in the early stages. There were no significant differences in the structural morphology or organelles involved in the secretion of royal jelly at different ages. Transcriptomics revealed a total of 1554 differentially expressed genes, which were mainly involved in fat metabolism, lipid transport, and energy metabolism. The extracellular matrix-receptor interaction pathway was significantly enriched and contributed to the royal jelly secretion process. These results elucidate the genetic basis of the role of the mandibular gland in royal jelly secretion in A. mellifera and provide a reference for the genetic improvement of bees with high royal jelly production in the future.

Evaluation of two decellularization methods in the development of a whole-organ decellularized rat liver scaffold.

AIM: Hepatic tissue engineering is considered as a possible alternative to liver transplantation for end-stage liver disease. Several methods of decellularization of xenogeneic liver are available to produce three-dimensional organ scaffolds for engineering liver tissues. However, rare studies have examined and compared the effectiveness of different methods on the structure and composition of intact decellularized liver extracellular matrix. METHODS: Two decellularization methods were adopted herein. Their effects on collagen, elastin, glycosaminoglycans (GAGs), hepatocyte growth factor (HGF) content and influence to the function of hepatocytes cultured in scaffolds were examined and compared. RESULTS: The complete tissue decellularization was successfully achieved after treatment with sodium dodecyl sulphate (SDS) and Triton X-100. The total absence of nuclear structures and removal of viable cells were confirmed by haematoxylin-eosin staining and scanning electron microscopy. Collagen was preserved after both treatments. However, the elastin content decreased to about 20% and 60%, the GAGs content decreased to about 10% and 50% and the HGF content decreased to about 20% and 60% of the native liver level after SDS and Triton X-100 treatment respectively. The Triton X-100-treated scaffolds were much superior than SDS-treated scaffolds in supporting liver-specific function, including albumin secretion (P = 0.001), urea synthesis (P = 0.002), ammonia elimination (P = 0.007) and mRNA expression levels of drug metabolism enzymes. CONCLUSION: This study suggested that liver extracellular matrix scaffolds constructed using perfusion of Triton X-100 as described herein might provide a more effective and ideal material for the usage in tissue engineering and regenerative medicine approaches.

CtsR regulation in mcsAB-deficient Gram-positive bacteria.

CtsR is an important repressor that modulates the transcription of class III stress genes in Gram-positive bacteria. In Bacillus subtilis, a model Gram-positive organism, the DNA binding activity of CtsR is regulated by McsAB-mediated phosphorylation of the protein where phosphorylated CtsR is a substrate for degradation by the ClpCP complex. Surprisingly, the mcsAB genes are absent from many Gram-positive bacteria, including streptococci; therefore, how CtsR activity is modulated in those bacteria remains unknown. Here we show that the posttranslational modulation of CtsR activity is different in Streptococcus mutans, a dental pathogen. We observed that of all of the Clp-related proteins, only ClpL is involved in the degradation of CtsR. Neither ClpP nor ClpC had any effect on the degradation of CtsR. We also found that phosphorylation of CtsR on a conserved arginine residue within the winged helix-turn-helix domain is necessary for modulation of the repressor activity of CtsR, as demonstrated by both in vitro and in vivo assays. We speculate that CtsR is regulated posttranslationally by a different mechanism in S. mutans and possibly in other streptococci.

An Atypical Case of Monomicrobial Clostridioides difficile Septicemia With No Gastrointestinal Manifestations.

An uncommon case of monomicrobial Clostridioides difficile septicemia in a 63-year-old man was reported in Zhejiang, China. Once diagnosed, vancomycin treatment cleared the infections. The patient had no remarkable medical history, and the inspection showed no overt gastrointestinal symptoms, though C. difficile was detected in his stool samples. However, we later defined that the C. difficile strain isolated from the blood sample was different from the one isolated from his stool using the whole genome sequencing analysis. By retrospective analysis of his medical record, we noticed that the man had a recent tooth extraction thus the bacterium may have invaded through the root canal. Therefore, we suggest that oral C. difficile colonization may be a potential risk factor for severe C. difficile septicemia, which could be clinically alarming.

Cisplatin and oxaliplatin inhibit gap junctional communication by direct action and by reduction of connexin expression, thereby counteracting cytotoxic efficacy.

Cisplatin [cis-diamminedichloroplatinum(II)]/oxaliplatin [1,2-diamminocyclohexane(trans-1)oxolatoplatinum(II)] toxicity is enhanced by functional gap junctions between treated cells, implying that inhibition of gap junctions may decrease cytotoxic activity of these platinum-based agents. This study investigates the effect of gap junction modulation by cisplatin/oxaliplatin on cytotoxicity in a transformed cell line. The effects were explored using junctional channels expressed in transfected HeLa cells and purified hemichannels. Junctional channels showed a rapid, dose-dependent decrease in dye coupling with exposure to cisplatin/oxaliplatin. With longer exposure, both compounds also decreased connexin expression. Both compounds inhibit the activity of purified connexin hemichannels, over the same concentration range that they inhibit junctional dye permeability, demonstrating that inhibition occurs by direct interaction of the drugs with connexin protein. Cisplatin/oxaliplatin reduced the clonogenic survival of HeLa cells at low density and high density in a dose-dependent manner, but to a greater degree at high density, consistent with a positive effect of gap junctional intercellular communication (GJIC) on cytotoxicity. Reduction of GJIC by genetic or pharmacological means decreased cisplatin/oxaliplatin toxicity. At low cisplatin/oxaliplatin concentrations, where effects on connexin channels are minimal, the toxicity increased with increased cell density. However, higher concentrations strongly inhibited GJIC, and this counteracted the enhancing effect of greater cell density on toxicity. The present results indicate that inhibition of GJIC by cisplatin/oxaliplatin decreases their cytotoxicity. Direct inhibition of GJIC and reduction of connexin expression by cisplatin/oxaliplatin may thereby compromise the effectiveness of these compounds and be a factor in the development of resistance to this class of chemotherapeutic agents.

Strain-Dependent Recognition of a Unique Degradation Motif by ClpXP in Streptococcus mutans.

Streptococcus mutans, a dental pathogen, has a remarkable ability to cope with environmental stresses. Under stress conditions, cytoplasmic proteases play a major role in controlling the stability of regulatory proteins and preventing accumulation of damaged and misfolded proteins. ClpXP, a well-conserved cytoplasmic proteolytic system, is crucial in maintaining cellular homeostasis in bacteria. ClpX is primarily responsible for recognition of substrates and subsequent translocation of unfolded substrates into the ClpP proteolytic compartment for degradation. In Escherichia coli, ClpX recognizes distinct motifs present at the C-terminal end of target proteins. However, recognition sequences for ClpXP in other bacteria, including S. mutans, are not known. In this study, using two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE) analysis, we have identified several putative substrates for S. mutans ClpXP. SsbA, which encodes a small DNA binding protein, is one such substrate that is degraded by ClpXP. By sequential deletions, we found that the last 3 C-terminal amino acids, LPF, are sufficient for ClpXP-mediated degradation. Addition of LPF at the C-terminal end of green fluorescent protein (GFP) rendered the protein completely degradable by ClpXP. Alterations of this tripeptide motif impeded ClpXP-mediated degradation. However, recognition of LPF by ClpXP is highly specific to some S. mutans strains (UA159, UA130, and N3209) since not all S. mutans strains recognize the motif. We speculate that an adaptor protein is involved in either substrate recognition or substrate degradation by ClpXP. Nevertheless, this is the first report of a unique recognition sequence for ClpXP in streptococci. IMPORTANCE Regulated proteolysis in bacteria is an important biological process that maintains protein homeostasis. ClpXP, an intracellular proteolytic complex, is the primary protease that is responsible for protein turnover. While the substrates for ClpXP were identified in Escherichia coli, the substrates for vast majority of bacteria are currently unknown. In this study, we identified a unique substrate for ClpXP-mediated degradation in Streptococcus mutans, a dental pathogen. We also found that a small motif composed of 3 amino acids is sufficient for ClpXP-mediated degradation. Identification of this motif will clearly help us to understand the pathogenesis of this organism and other related pathogens.

A functional drug delivery platform for targeting and imaging cancer cells based on Pluronic F127.

Functional polymeric micelles play an important role in the efficient delivery of therapeutic drugs into tumours. In this study, a functional drug delivery platform with ligands for targeting and fluorescent imaging was designed based on Pluronic F127 (PF127). Using folic acid (FA) and fluorescein isothiocyanate (FITC) to chemically conjugate with PF127, two functional polymers, Pluronic F127-FA (PF127-FA) and Pluronic F127-FITC (PF127-FITC), were synthesized. Solasodine-loaded micelles were then prepared via the thin-film hydration method. By employing A549 and HeLa cells, the results of in vitro cell assays performed using confocal laser scanning microscopy and flow cytometry suggested that the proposed micelles could provide the desired specific targeting and fluorescent imaging functions. In addition, the results of in vitro cytotoxicity experiments showed that the growth inhibition rates of A549 and HeLa cells treated with solasodine-loaded micelles were remarkably higher than those of cells treated with free solasodine. Solasodine-loaded micelles exhibited a more distinct inhibitory effect against HeLa cells than against A549 cells. Thus, an effective drug delivery system for targeting and imaging cancer cells was developed.

[Effect of sustained-release basic fibroblast growth factor on healing of bile duct defect in pigs].

OBJECTIVE: To investigate the effects of sustained-release basic fibroblast growth factor (bFGF) on healing of bile duct defect. METHODS: A model of bile duct wall defect (2 cm in length and 1/3-2/3 of the bile duct circumference in width) was made in 24 pigs (male or female, weighing 15-30 kg), and then defect was repaired with sustained-release bFGF collagen membrane (2.0 cm x 1.0 cm x 0.5 cm in size) in the experimental group (n=12) or with collagen membrane (2.0 cm x 1.0 cm x 0.5 cm in size) alone in the blank control group (n=12). Another 4 healthy pigs were used to obtain normal bile duct as normal control group. The survival condition of pigs was observed after operation; at 1, 2, and 3 months after operation, the blood sampling was collected to test the changes of liver function, and the bile duct specimens were harvested to count the microvessel density (MVD) and submucosal gland by HE staining and immunohistochemistry staining; and at 3 months after operation, cholangiography examination was done. RESULTS: All the animals survived to completion of the experiment. Intra-abdominal adhesion was serious in the experimental and blank control groups at 1 week after operation, but the adhesion was markedly improved in the experimental group when compared with the blank control group with time passing. The liver function test showed that alkaline phosphatase in the experimental group was significantly lower than that in the blank control group at 2 and 3 months (P < 0.05), but no significant difference in aspartate aminortransferase, total bilirubin, and albumin was found among 3 groups (P > 0.05). The histology and immunohistochemistry staining observations showed that the regeneration rates of submucosal glands and epithelium in the experimental group were faster than those in the blank control group; defect was covered with the epithelium at 2 months, and the structure was similar to that of normal control group at 3 months; and the edema and inflammation infiltration were reduced when compared with the blank control group. The counts of MVD and submucosal gland were significantly higher than those in blank control group and normal control group at 1 month after operation (P < 0.05), and then decreased and remained at normal levels at 2 months after operation. There was a positive correlation between submucosal gland counting and MVD counting in 3 groups after operation (P < 0.01). The cholangiography examination showed no biliary dilatation or cholelithiasis after 3 months in experimental group and blank control group. CONCLUSION: Sustained-release bFGF can promote healing of bile duct defect by accelerating the vascularization, gland regeneration, and epithelialization.

Right ventricular outflow tract patch reconstruction in anomalous origin of right coronary artery.

A new technique to repair tetralogy of Fallot or double-outlet right ventricle with an anomalous right coronary artery arising from the left anterior descending coronary artery and crossing the right ventricular outflow tract is described. The right coronary artery was mobilized, transected, and re-implanted into the ascending aorta. The right ventricular outflow tract and ventricle septal defect were repaired through a ventriculotomy and pulmonary arteriotomy. The right ventricular outflow tract and pulmonary annulus were reconstructed with a pericardial patch. Five consecutive patients underwent this technique between August 2007 and October 2008. The indications of the electrocardiograms were no heart ischemia in all patients at mean follow-ups conducted at 5 to 19 months. All the patients were in New York Heart Association functional class I at the time of last follow-up.

2-aminoethoxydiphenyl borate directly inhibits channels composed of connexin26 and/or connexin32.

2-aminoethoxydiphenyl borate (2-APB), a commonly used blocker of IP3-induced calcium ion release and of store-operated channels, inhibits gap junction conductance when applied to cultured cells. The character and pharmacology of this inhibition was explored using 1) hemichannels composed of connexin32 (Cx32) and/or connexin26 (Cx26) purified from native sources and from transfected HeLa cells in which the connexin had a cleavable C-terminal epitope tag and 2) the corresponding junctional channels. Using reconstituted hemichannels in a liposome-based transport-specific fractionation assay (TSF), 2-APB reversibly inhibited homomeric Cx32 and heteromeric Cx26/Cx32 channels from native tissue and their tagged forms from HeLa cells. The IC50-TSF value of the inhibition was approximately 47 microM at pH 6.5. 2-APB did not inhibit tagged homomeric Cx26 channels even after tag cleavage (leaving several amino acids at the carboxyl terminus). Protonated 2-APB is the inhibitory agent, but channel sensitivity to 2-APB also increases as pH is lowered. To help define the chemical requirements for inhibition, the effects of four structural analogs of 2-APB were determined. The inhibitory action of 2-APB was shown to be distinct from that of aminosulfonates. 2-APB and its analogs, except phenytoin, inhibited dye-coupling through junctional channels formed by all the tagged channel forms except Cx26, consistent with the TSF studies. However 2-APB significantly inhibited dye coupling between cells expressing untagged Cx26, suggesting that an unmodified C terminus is required for action on Cx26 channels. These results show that protonated 2-APB directly and reversibly inhibits connexin channels composed of Cx26 and/or Cx32 and suggest involvement of the carboxyl-terminal domain.

Biochemical requirements for inhibition of Connexin26-containing channels by natural and synthetic taurine analogs.

Previous work has shown that protonated taurine and aminosulfonate pH buffers, including HEPES, can directly and reversibly inhibit connexin channels that contain connexin26 (Cx26) (Bevans, C. G., and Harris, A. L. (1999) J. Biol. Chem. 274, 3711-3719). The structural requirements for this inhibition were explored by studies of the effects of structural analogs of taurine on the activity of Cx26-containing reconstituted hemichannels from native tissue. Several analogs inhibited the channels, with a range of relative affinities and efficacies. Each active compound contains a protonated amine separated from an ionized sulfonate or sulfinate moiety by several methylene groups. The inhibition is eliminated if the sulfonate/sulfinate moiety or the amine is not present. Compounds that contain a protonated amine but lack a sulfonate/sulfinate moiety do not inhibit but do competitively block the effect of the active compounds. Compounds that lack the protonated amine do not significantly inhibit or antagonize inhibition. The results suggest involvement of the protonated amine in binding and of the ionized sulfur-containing moiety in effecting the inhibition. The maximal effect of the inhibitory compounds is enhanced when a carboxyl group is linked to the alpha-carbon. Inhibition but not binding is stereospecific, with l-isomers being inhibitory and the corresponding d-isomers being inactive but able to antagonize inhibition by the l-isomers. Whereas not all connexins are sensitive to aminosulfonates, the well defined structural requirements described here argue strongly for a highly specific regulatory interaction with some connexins. The finding that cytoplasmic aminosulfonates inhibit connexin channels whereas other cytoplasmic compounds antagonize the inhibition suggests that gap junction channels are regulated by a complex interplay of cytoplasmic ligands.