Shank2 identifies a subset of glycinergic neurons involved in altered nociception in an autism model

BACKGROUND

Autism Spectrum Disorders (ASD) patients experience disturbed nociception in the form of either hyposensitivity to pain or allodynia. A substantial amount of processing of somatosensory and nociceptive stimulus takes place in the dorsal spinal cord. However, many of these circuits are not very well understood in the context of nociceptive processing in ASD.

METHODS

We have used a Shank2^-/- mouse model, which displays a set of phenotypes reminiscent of ASD, and performed behavioural and microscopic analysis to investigate the role of dorsal horn circuitry in nociceptive processing of ASD.

RESULTS

We determined that Shank2^-/- mice display increased sensitivity to formalin pain and thermal preference, but a sensory specific mechanical allodynia. We demonstrate that high levels of Shank2 expression identifies a subpopulation of neurons in murine and human dorsal spinal cord, composed mainly by glycinergic interneurons and that loss of Shank2 causes the decrease in NMDAR in excitatory synapses on these inhibitory interneurons. In fact, in the subacute phase of the formalin test, glycinergic interneurons are strongly activated in wild type (WT) mice but not in Shank2^-/- mice. Consequently, nociception projection neurons in laminae I are activated in larger numbers in Shank2^-/- mice.

LIMITATIONS

Our investigation is limited to male mice, in agreement with the higher representation of ASD in males; therefore, caution should be applied to extrapolate the findings to females. Furthermore, ASD is characterized by extensive genetic diversity and therefore the findings related to Shank2 mutant mice may not necessarily apply to patients with different gene mutations. Since nociceptive phenotypes in ASD range between hyper- and hypo-sensitivity, diverse mutations may affect the circuit in opposite ways.

CONCLUSION

Our findings prove that Shank2 expression identifies a new subset of inhibitory interneurons involved in reducing the transmission of nociceptive stimuli and whose unchecked activation is associated with pain hypersensitivity. We provide evidence that dysfunction in spinal cord pain processing may contribute to the nociceptive phenotypes in ASD.

CLARITY increases sensitivity and specificity of fluorescence immunostaining in long-term archived human brain tissue

BACKGROUND

Post mortem human brain tissue is an essential resource to study cell types, connectivity as well as subcellular structures down to the molecular setup of the central nervous system especially with respect to the plethora of brain diseases. A key method is immunostaining with fluorescent dyes, which allows high-resolution imaging in three dimensions of multiple structures simultaneously. Although there are large collections of formalin-fixed brains, research is often limited because several conditions arise that complicate the use of human brain tissue for high-resolution fluorescence microscopy.

RESULTS

In this study, we developed a clearing approach for immunofluorescence-based analysis of perfusion- and immersion-fixed post mortem human brain tissue, termed human Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging / Immunostaining / In situ hybridization-compatible Tissue-hYdrogel (hCLARITY). hCLARITY is optimized for specificity by reducing off-target labeling and yields very sensitive stainings in human brain sections allowing for super-resolution microscopy with unprecedented imaging of pre- and postsynaptic compartments. Moreover, hallmarks of Alzheimer's disease were preserved with hCLARITY, and importantly classical 3,3'-diaminobenzidine (DAB) or Nissl stainings are compatible with this protocol. hCLARITY is very versatile as demonstrated by the use of more than 30 well performing antibodies and allows for de- and subsequent re-staining of the same tissue section, which is important for multi-labeling approaches, e.g., in super-resolution microscopy.

CONCLUSIONS

Taken together, hCLARITY enables research of the human brain with high sensitivity and down to sub-diffraction resolution. It therefore has enormous potential for the investigation of local morphological changes, e.g., in neurodegenerative diseases.

Tinospora cordifolia modulates the seminal parameters, leakage of intracellular enzymes and seminal antioxidants in equilibrated and cryopreserved semen of Sahiwal bulls

The present study was undertaken to assess the effects of stem extract of Tinospora cordifolia (Giloy or Guduchi) in the semen extender on seminal parameters, leakage of intracellular enzymes and antioxidants in semen of Sahiwal bull. A total of 48 ejaculates from four bulls were selected for the study. Spermatozoa of 25×10⁶ were incubated in 100, 300 and 500 μg of stem extract of Guduchi as Gr II, III and IV, respectively and pre-freeze and post-thaw semen samples were analysed for seminal parameters (motility, viability, total sperm abnormality; TSA, plasma membrane integrity; PMI, and acrosomal integrity; AcI), intracellular enzymes (aspartate aminotransferase; AST and lactate dehydrogenase; LDH) and seminal antioxidants (superoxide dismutase; SOD and catalase) in comparison with an untreated control group (Gr I). The results revealed that stem extract treated semen had significantly (p<0.05) higher motility, viability, PMI, AcI, SOD and catalase and had significantly (p<0.05) lower TSA, AST and LDH compared to those in untreated control group at pre-freeze and post-thaw stages. Semen treated with 100 μg stem extract /25×10⁶ spermatozoa had significantly (p<0.05) higher motility, viability, PMI, AcI, SOD and catalase and had significantly (p<0.05) lower TSA, AST and LDH compared to those in control, 300, and 500 μg treated groups at pre-freeze and post-thaw stages. Further, these seminal parameters and antioxidants were showing decreasing trend and TSA and leakage of intra-cellular enzymes were showing increasing trend from Gr II to Gr IV at pre-freeze and post-thaw stages. Thus, 100 μg/25×10⁶ spermatozoa were optimum or suitable dose for cryopreservation of Sahiwal bull semen. The study concluded that T. cordifolia stem extract 100 μg/25×10⁶ spermatozoa in the semen extender can be effectively utilized to reduce the oxidative stress and improve the pre-freeze and post-thaw seminal parameters in Sahiwal bull. However, further studies on effects of different concentrations of stem extract on in-vitro or in-vivo fertility trials are to be conducted to assess the impact of the stem extract supplementation in the semen extender on field pregnancy outcome in bovine species.

Super-Resolution Microscopy Reveals a Direct Interaction of Intracellular Mycobacterium tuberculosis with the Antimicrobial Peptide LL-37

The antimicrobial peptide LL-37 inhibits the growth of the major human pathogen Mycobacterium tuberculosis (Mtb), but the mechanism of the peptide–pathogen interaction inside human macrophages remains unclear. Super-resolution imaging techniques provide a novel opportunity to visualize these interactions on a molecular level. Here, we adapt the super-resolution technique of stimulated emission depletion (STED) microscopy to study the uptake, intracellular localization and interaction of LL-37 with macrophages and virulent Mtb. We demonstrate that LL-37 is internalized by both uninfected and Mtb infected primary human macrophages. The peptide localizes in the membrane of early endosomes and lysosomes, the compartment in which mycobacteria reside. Functionally, LL-37 disrupts the cell wall of intra- and extracellular Mtb, resulting in the killing of the pathogen. In conclusion, we introduce STED microscopy as an innovative and informative tool for studying host–pathogen–peptide interactions, clearly extending the possibilities of conventional confocal microscopy.

Synaptic FUS Localization During Motoneuron Development and Its Accumulation in Human ALS Synapses

Mutations in the fused in Sarcoma (FUS) gene induce cytoplasmic FUS aggregations, contributing to the neurodegenerative disease amyotrophic lateral sclerosis (ALS) in certain cases. While FUS is mainly a nuclear protein involved in transcriptional processes with limited cytoplasmic functions, it shows an additional somatodendritic localization in neurons. In this study we analyzed the localization of FUS in motoneuron synapses, these being the most affected neurons in ALS, using super-resolution microscopy to distinguish between the pre- and postsynaptic compartments. We report a maturation-based variation of FUS localization in rodent synapses where a predominantly postsynaptic FUS was observed in the early stages of synaptic development, while in mature synapses the protein was entirely localized in the axonal terminal. Likewise, we also show that at the synapse of human motoneurons derived from induced pluripotent stem cells of a healthy control, FUS is mainly postsynaptic in the early developmental stages. In motoneurons derived from ALS patients harboring a very aggressive juvenile FUS mutation, increased synaptic accumulation of mutated FUS was observed. Moreover increased aggregation of other synaptic proteins Bassoon and Homer1 was also detected in these abnormal synapses. Having demonstrated changes in the FUS localization during synaptogenesis, a role of synaptic FUS in both dendritic and axonal cellular compartments is probable, and we propose a gain-of-toxic function due to the synaptic aggregation of mutant FUS in ALS.

Dysregulation of a novel miR-1825/TBCB/TUBA4A pathway in sporadic and familial ALS

Genetic and functional studies suggest diverse pathways being affected in the neurodegenerative disease amyotrophic lateral sclerosis (ALS), while knowledge about converging disease mechanisms is rare. We detected a downregulation of microRNA-1825 in CNS and extra-CNS system organs of both sporadic (sALS) and familial ALS (fALS) patients. Combined transcriptomic and proteomic analysis revealed that reduced levels of microRNA-1825 caused a translational upregulation of tubulin-folding cofactor b (TBCB). Moreover, we found that excess TBCB led to depolymerization and degradation of tubulin alpha-4A (TUBA4A), which is encoded by a known ALS gene. Importantly, the increase in TBCB and reduction of TUBA4A protein was confirmed in brain cortex tissue of fALS and sALS patients, and led to motor axon defects in an in vivo model. Our discovery of a microRNA-1825/TBCB/TUBA4A pathway reveals a putative pathogenic cascade in both fALS and sALS extending the relevance of TUBA4A to a large proportion of ALS cases.

The Effect of the Canine ABCB1-1Δ Mutation on Sedation after Intravenous Administration of Acepromazine

BACKGROUND

Dog breeds with the ABCB1-1Δ mutation have substantially truncated nonfunctional P-glycoprotein. Dogs homozygous for this mutation (mut/mut) are susceptible to the toxic adverse effects of ivermectin, loperamide, and vincristine. Anecdotal reports suggested ABCB1 mut/mut dogs showed increased depth and duration of acepromazine sedation.

HYPOTHESIS/OBJECTIVES

That ABCB1 mut/mut dogs have increased depth and duration of sedation after acepromazine IV compared to normal dogs (nor/nor).

ANIMALS

Twenty-nine rough-coated collies were divided into 3 groups of dogs based on their ABCB1 genotype: 10 mut/mut, 10 mut/nor, and 9 nor/nor.

METHODS

Dogs were given 0.04 mg/kg of acepromazine IV. Level of sedation, heart rate, respiratory rate, and blood pressure were recorded for 6 hours after acepromazine administration. Area under the curves (AUCs) of the normalized sedation score results were calculated and compared.

RESULTS

The median sedation scores for ABCB1 mut/mut dogs were higher than nor/nor dogs at all time points and were higher in mut/nor dogs for the first 2 hours. These differences were not found to be significant for any individual time point (P > .05). The median sedation score AUC for mut/mut dogs was significantly higher than nor/nor dogs (P = .028), but the AUC for mut/nor dogs was not (P = .45). There were no significant differences between groups for heart rate, respiratory rate, and blood pressure (P > .05).

CONCLUSIONS AND CLINICAL IMPORTANCE

In ABCB1 mut/mut dogs acepromazine dose rates should be reduced and careful monitoring performed during sedation.

Super-Resolution Microscopy Reveals Presynaptic Localization of the ALS/FTD Related Protein FUS in Hippocampal Neurons

Fused in Sarcoma (FUS) is a multifunctional RNA-/DNA-binding protein, which is involved in the pathogenesis of the neurodegenerative disorders amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). A common hallmark of these disorders is the abnormal accumulation of mutated FUS protein in the cytoplasm. Under normal conditions FUS is confined to the nuclear compartment, in neurons, however, additional somatodendritic localization can be observed. In this study, we carefully analyzed the subcellular localization of endogenous FUS at synaptic sites of hippocampal neurons which are among the most affected cell types in FTD with FUS pathology. We could confirm a strong nuclear localization of FUS as well as its prominent and widespread neuronal expression throughout the adult and developing rat brain, particularly in the hippocampus, the cerebellum and the outer layers of the cortex. Intriguingly, FUS was also consistently observed at synaptic sites as detected by neuronal subcellular fractionation as well as by immunolabeling. To define a pre- and/or postsynaptic localization of FUS, we employed super-resolution fluorescence localization microscopy. FUS was found to be localized within the axon terminal in close proximity to the presynaptic vesicle protein Synaptophysin1 and adjacent to the active zone protein Bassoon, but well separated from the postsynaptic protein PSD-95. Having shown the presynaptic localization of FUS in the nervous system, a novel extranuclear role of FUS at neuronal contact sites has to be considered. Since there is growing evidence that local presynaptic translation might also be an important mechanism for plasticity, FUS - like the fragile X mental retardation protein FMRP - might act as one of the presynaptic RNA-binding proteins regulating this machinery. Our observation of presynaptic FUS should foster further investigations to determine its role in neurodegenerative diseases such as ALS and FTD.

Biotin-conjugated fusogenic liposomes for high-quality cell purification

Purification of defined cell populations from mixed primary cell sources is essential for many biomedical and biotechnological applications but often very difficult to accomplish due to missing specific surface markers. In this study, we developed a new approach for efficient cell population separation based on the specific membrane fusion characteristics of distinct cell types upon treatment with fusogenic liposomes. When such liposomes are conjugated with biotin, specific cell populations can be efficiently surface functionalized by biotin after liposomal treatment while other populations remain unlabeled. Due to the high affinity of biotin for avidin-like proteins, biotin functionalized cells are ideal targets for conjugation of e.g. avidin tagged magnetic beads, fluorophores or antibodies with bioanalytical relevance. Here, based on the differential biotinylation of distinct cell populations high quality separation of cardiac fibroblasts from myocytes, and cerebromicrovascular endothelial cells from fibroblasts was successfully established.

A new paradigm to understand and treat diabetic neuropathy

The clinical symptoms of diabetic neuropathy (DN) manifest in a time dependent manner as a positive symptoms (i. e. pain, hypersensitivity, tingling, cramps, cold feet etc.) during its early stages and by a loss of function (i. e. loss of sensory perception, delayed wound healing etc.) predominating in the later stages. Elevated blood glucose alone cannot explain the development and progression of DN and the lowering of blood glucose is insufficient in preventing and/or reversing neuropathy in patients with type 2 diabetes. Recently it has been shown that the endogenous reactive metabolite methylglyoxal (MG) can contribute to the gain of function via post-translational modification in DN of neuronal ion channels involved in chemosensing and action potential generation in nociceptive nerve endings. Dicarbonyls, such as MG, that are elevated in diabetic patients, modify DNA as well as extra- and intracellular proteins, leading to the formation of advanced glycation endproducts (AGEs). Increased formation of AGEs leads to increased cellular stress, dysfunction and ultimately cell death. The interaction of AGE-modified proteins through cell surface receptors, such as RAGE, can lead to increased cellular activation and sustained inflammatory responses, which are the molecular hallmarks of the later, degenerative, stages of DN. The direct and indirect effects of dicarbonyls on nerves or neuronal microvascular network provides a unifying mechanism for the development and progression of DN. Targeting the accumulation of MG and/or prevention of RAGE interactions may therefore provide new, more effective, therapeutic approaches for the treatment of DN.

Whole-body PET acceptance test in 2D and 3D using NEMA NU 2-2001 protocol

Integrated PET/CT has emerged as an integral component of oncology management because of its unique potential of providing both functional and morphological images in a single imaging session. In this work, performance of the ‘bismuth germinate (BGO) crystal’-based PET of a newly installed Discovery ST PET/CT was evaluated in 2D and 3D mode for whole-body scanning using National Electrical Manufacturers Association (NEMA) NU 2-2001 protocol and the recommended phantoms. During the entire measurements, the system operates with an energy window of 375-650 keV and 11.7 ns coincidence time window. The set of tests performed were spatial resolution, sensitivity, scatter fraction (SF) and counting rate performance. The average transaxial and axial spatial resolution measured as full width at half maximum (FWHM) of the point spread function at 1 cm (and 10 cm) off-axis was 0.632 (0.691) and 0.491 (0.653) cm in 2D and 0.646 (0.682) and 0.54 (0.601) cm in 3D respectively. The average sensitivity for the two radial positions (R = 0 cm and R = 10 cm) was 2.56 (2.63) cps/kBq in 2D and 11.85 (12.14) cps/kBq in 3D. The average scatter fraction was 19.79% in 2D and 46.19% in 3D. The peak noise equivalent counting rate (NECR) evaluated with single random subtraction was 89.41 kcps at 49 kBq/cc in 2D and 60 kcps at 12 kBq/cc in 3D acquisition mode. The NECR with delayed random subtraction was 61.47 kcps at 40.67 kBq/cc in 2D and 45.57 kcps at 16.45 kBq/cc in 3D. The performance of the PET scanner was satisfactory within the manufacturer-specified limits. The test result of PET shows excellent system sensitivity with relatively uniform resolution throughout the FOV, making this scanner highly suitable for whole-body studies.

Radiation therapy with implanted cardiac pacemaker devices: a clinical and dosimetric analysis of patients and proposed precautions

AIMS

To report the radiation planning dosimetric aspects and clinical outcomes of patients with implanted cardiac pacemakers.

MATERIALS AND METHODS

Between 2005 and 2009, eight patients with in situ cardiac pacemakers of varied primary site were treated at our hospital. All patients underwent computed tomography-based treatment planning. The target volumes, organs at risk and pacemaker device were all contoured. A treatment plan optimally covering the target area and maximally sparing the pacemaker was generated. All patients were evaluated at baseline, during radiotherapy and after radiotherapy conclusion by a cardiologist as well as pacemaker company personnel.

RESULTS

The median age at presentation was 67 (range 53-77) years. There were three men with head and neck primaries, two men with lung primaries and three women with breast primaries. The prescribed dose ranged from 45 to 70 Gy in 25-35 fractions with a daily dose of 1.8-2.0 Gy. Four patients had the pacemaker implanted on the same side as the radiotherapy target. The dose ranges for the minimum, mean and maximum doses to the pacemaker were 0.06-2.0, 0.07-20.6 and 0.14-60.0 Gy, respectively. Radiation therapy was safely delivered in all patients without any untoward effects. At 5 months of median follow-up, all patients were well with no malfunction of the pacemaker.

CONCLUSION

A series of eight patients with in situ pacemakers treated with radiotherapy is reported. Radiotherapy can be safely delivered in patients with implanted cardiac pacemakers. However, it mandates a cautious approach in planning and treatment delivery to ensure the least possible dose to the pacemaker. Close liaison with the cardiologist and a pacemaker clinic before, during and after the course of treatment is essential to ensure patient safety.

Accelerated partial breast irradiation with interstitial brachytherapy as the sole modality of radiation for women with low risk early stage breast cancer

10661

Purpose: The aim of the study is to evaluate the safety and feasibility of radical brachytherapy for accelerated partial breast irradiation (APBI) and to study the outcome with respect to local control and survival. Materials and Methods: During May 2000 to December 2004, 115 women participated in the ongoing prospective study of APBI using interstitial brachytherapy as the sole modality of radiation for early breast cancer. Women with age > 40 years, single tumour up to 3 cm without diffuse microcalcification and clinically negative axilla were considered suitable. Brachytherapy was done either intraoperatively during the breast conserving surgery or postoperatively using 2–4 planes. Tumor bed demarcation was done with radiopaque clips placed during surgery, CT scans, ultrasonography and/or fluoroscopy. Cavity with 1cm margin was treated based on orthogonal pair of X rays to a dose of 34 Gy in 10 fractions over 1 week with twice daily fractionation using high dose rate iridium source. Results: Implant was done postoperatively in 35 patients while in remaining patients it was done intraoperatively. Implant procedure was tolerated well by all the patients. In 8 patients only 3 or 4 fractions of HDR Brachytherapy were delivered and this was followed by 45 Gy/25 # whole breast radiation therapy for following reasons: positive nodes (4), EIC positive (3) and poor implant coverage (1). At a median follow up of 23 months, the actuarial local control rate is 100%. Three year actuarial disease free survival is 93% while the overall survival is 100%. Complications included fat necrosis in 5 and wound gape in 4 patients. Cosmesis was good to excellent in 60% of the patients. Conclusion: In this ongoing prospective study, APBI using radical interstitial implant was well tolerated and appears to be safe and feasible in appropriately selected patients. Further follow up is needed for confirm the long term safety of the procedure.

No significant financial relationships to disclose.

Hypohidrotic ectodermal dysplasia: a unique approach to esthetic and prosthetic management: a case report

Hypohidrotic ectodermal dysplasia is a rare congenital disease that affects several ectodermal structures. The condition is usually transmitted as an x-linked recessive trait, in which gene is carried by the females and manifested in males. Manifestations of the disease differ in severity and involve teeth, skin, hair, nails and sweat and sebaceous gland. Ectodermal dysplasia is usually a difficult condition to manage. Prosthodontically, because of the typical oral deficiencies, and afflicted individuals are quite young to receive extensive prosthodontic treatment, which restores their appearance and helps them, for the development of positive self-image. This case report describes the management of upper jaw with over denture with copings on existing teeth i.e. two permanent peg shaped centrals as well as lateral incisors. However with adequate of retainer lower denture was provided with a new treatment modality.

Ultrasonic nebulization of cationic lipid-based gene delivery systems for airway administration

PURPOSE

This study relates to the development of gene therapies for the treatment of lung diseases. It describes for the first time the use of ultrasonic nebulization for administration of plasmid/lipid complexes to the lungs to transfect lung epithelial cells.

METHODS

Plasmid complexed to cationic liposomes at a specific stoichiometric ratio was nebulized using an ultrasonic nebulizer. We assessed: (i) the stability of plasmid and plasmid/lipid complexes to ultrasonic nebulization, (ii) the in vitro activity of plasmid in previously nebulized plasmid/lipid complex, (iii) the in vivo transgene expression in lungs following intratracheal instillation of nebulized plasmid/lipid formulations compared to un-nebulized complexes, (iv) the emitted dose from an ultrasonic nebulizer using plasmid/lipid complexes of different size, and (v) the transgene expression in lungs following oral inhalation of aerosolized plasmid/lipid complex generated using an ultrasonic nebulizer.

RESULTS

Integrity of plasmid formulated with cationic lipids, and colloidal stability of the plasmid/lipid complex were maintained during nebulization. In contrast, plasmid alone formulated in 10% lactose was fragmented during nebulization. The efficiency of transfection of the complex before and after nebulization was comparable. Nebulization produced respirable aerosol particles. Oral exposure of rodents for 10 minutes to aerosol produced from the ultrasonic nebulizer resulted in transgene expression in lungs in vivo.

CONCLUSIONS

The performance characteristics of the ultrasonic nebulizer with our optimized plasmid/lipid formulations suggests that this device can potentially be used for administering gene medicines to the airways in clinical settings for the treatment of respiratory disorders.

Activated lymphocytes reduce adherence of Aspergillus fumigatus

Lymphocytes comprise up to 30% of the cells present in human bronchoalveolar lavage fluid and thus could participate in host response to infectious Aspergillus fumigatus conidia. We have examined the possibility that lymphocytes might play a role during early infection by either damaging the fungus or interfering with adherence. When incubated with A. fumigatus conidia for 20 h, highly purified 5-day-old lymphocytes activated with either IL-2 or phytohaemagglutinin, but not untreated lymphocytes, were consistently able to reduce residual fungal biomass as estimated by a metabolic assay. T lymphocytes, but not NK cells, appeared to be responsible for this activity. Lymphocytes bound both A. fumigatus conidia and hyphae, and the antifungal activity of the lymphocytes required direct lymphocyte fungus contact. In a separate set of experiments using release of 51Cr from 51Cr-loaded fungi as an estimate of fungal damage, lymphocyte-induced loss of fungal biomass was found to be due to loss of fungal adherence rather than to direct fungal damage. The detached hyphae were also found to be metabolically intact and to have normal morphology by electron microscopy. These data demonstrate that IL-2- and phytohaemagglutinin-activated lymphocytes exhibit a contact-dependent ability to reduce adherence of germinating conidia of A. fumigatus to a surface.

Target specific optimization of cationic lipid-based systems for pulmonary gene therapy

PURPOSE

Cationic lipids are capable of transferring foreign genes to the pulmonary epithelium in vivo. It is becoming increasingly clear that factors other than lipid molecular structure also influence efficiency of delivery using cationic lipid systems. This study is aimed at evaluating the effect of formulation variables such as cationic lipid structure, cationic lipid/DNA ratio, particle size, co-lipid content and plasmid topology on transgene expression in the lung.

METHODS

The effect of varying the surface and colloidal properties of cationic lipid-based gene delivery systems was assessed by intratracheal instillation into rats. An expression plasmid encoding chloramphenicol acetyl transferase (CAT) was used to measure transgene expression.

RESULTS

Cationic lipid structure, cationic lipid/DNA ratio, particle size, co-lipid content and topology of the plasmid, were found to significantly affect transgene expression. Complexation with lipids was found to have a protective effect on DNA integrity in bronchoalveolar lavage fluid (BALF). DNA complexed with lipid showed enhanced persistence in rat lungs as measured by quantitative polymerase chain reaction.

CONCLUSIONS

Fluorescence microscopy analysis indicated that the instilled formulation reaches the lower airways and alveolar region. Data also suggests cationic lipid-mediated gene expression is primarily localized in the lung parenchyma and not infiltrating cells isolated from the BALF.

Oligonucleotide targeting to alveolar macrophages by mannose receptor-mediated endocytosis

Antisense oligonucleotides (ONs) have proven useful for selective inhibition of gene expression. However, their effective use is limited by inefficient cellular uptake and lack of cellular targeting. In this paper, we report a drug targeting system which utilizes mannose receptor-mediated endocytosis to enhance cellular uptake of ONs in alveolar macrophages (AMs). The system employs a molecular complex consisting of partially substituted mannosylated poly(L-lysine) (MPL), electrostatically linked to a 5' fluorescently labeled ON. Upon recognition by the macrophage mannose receptors, the MPL was internalized by the receptor-mediated pathway, co-transporting the ON. Our results indicate that the AMs treated with the MPL:ON complex exhibited a significant increase in ON uptake (up to 17-fold) over free ON-treated controls. Effective ON uptake was shown to require the recognition of the mannose moiety since unmodified polylysine was much less effective in promoting ON uptake. Specific internalization of the ON:MPL complex by the mannose receptor pathway was verified by competitive inhibition using mannosylated albumin. Under this condition, the ON complex uptake was inhibited. The requirement of mannose receptors for complex uptake was further demonstrated using a macrophage cell line, J774.1, which expresses a low level of mannose receptors. When treated with the complex, these cells showed no susceptibility to ON uptake, thus suggesting the targeting ability of the carrier system to the AMs. Following cellular internalization, the ON complex appeared largely accumulated in endocytic vesicles. Enhanced endosomal exit of the ON was achieved using a fusogenic peptide derived from the amino terminal sequence of influenza virus hemagglutinin HA2. Cytotoxicity studies showed that at the concentrations effectively enhancing ON uptake, both MPL and the fusogenic peptide caused no toxic effects to the cells, thereby suggesting their potential safety and utilization in vivo.