Disruption of glycosylation enhances ubiquitin-mediated proteasomal degradation of Shadoo in Scrapie-infected rodents and cultured cells

Shadoo (Sho) is an N-glycosylated glycophosphatidylinositol-anchored protein that is expressed in the brain and exhibits neuroprotective properties. Recently, research has shown that a reduction of Sho levels may reflect the presence of PrPSc in the brain. However, the possible mechanism by which prion infection triggers down-regulation of Sho remains unclear. In the present study, Western blot and immunohistochemical assays revealed that Sho, especially glycosylated Sho, declined markedly in the brains of five scrapie agent-infected hamsters and mice at the terminal stages. Analyses of the down-regulation of Sho levels with the emergence of PrPSc C2 proteolytic fragments did not identify close association in all tested scrapie-infected models. To further investigate the mechanism of depletion of Sho in prion disease, a Sho-expressing plasmid with HA tag was introduced into a scrapie-infected cell line, SMB-S15, and its normal cell line, SMB-PS. Western blot assay revealed dramatically decreased Sho in SMB-S15 cells, especially its glycosylated form. Proteasome inhibitor MG132 reversed the decrease of nonglycosylated Sho, but had little effect on glycosylated Sho. N-acetylglucosamine transferase inhibitor tunicamycin efficiently reduced the glycosylations of Sho and PrPC in SMB-PS cells, while two other endoplasmic reticulum stress inducers showed clear inhibition of diglycosylated PrPC, but did not change the expression level and profile of Sho. Furthermore, immunoprecipitation of HA-Sho illustrated ubiquitination of Sho in SMB-S15 cells, but not in SMB-PS cells. We propose that the depletions of Sho in scrapie-infected cell lines due to inhibition of glycosylation mediate protein destabilization and subsequently proteasome degradation after modification by ubiquitination.

Macromolecular prodrug of dexamethasone prevents particle-induced peri-implant osteolysis with reduced systemic side effects

Aseptic implant loosening related to implant wear particle-induced inflammation is the most common cause of failure after joint replacement. Modulation of the inflammatory reaction to the wear products represents a rational approach for preventing aseptic implant failure. Long-term treatment using anti-inflammatory agents, however, can be associated with significant systemic side effects due to the drugs' lack of tissue specificity. To address this issue, N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-dexamethasone conjugate (P-Dex) was developed and evaluated for prevention of wear particle-induced osteolysis and the loss of fixation in a murine prosthesis failure model. Daily administration of free dexamethasone (Dex) was able to prevent wear particle-induced osteolysis, as assessed by micro-CT and histological analysis. Remarkably, monthly P-Dex administration (dose equivalent to free Dex treatment) was equally effective as free dexamethasone, but was not associated with systemic bone loss (a major adverse side effect of glucocorticoids). The reduced systemic toxicity of P-Dex is related to preferential targeting of the sites of wear particle-induced inflammation and its subcellular sequestration and retention by local inflammatory cell populations, resulting in sustained therapeutic action. These results demonstrate the feasibility of utilizing a macromolecular prodrug with reduced systemic toxicity to prevent wear particle-induced osteolysis.

Abortive cell cycle events in the brains of scrapie-infected hamsters with remarkable decreases of PLK3/Cdc25C and increases of PLK1/cyclin B1

Polo-like kinases (PLKs) consist of a family of kinases which play critical roles during multiple stages of cell cycle progression. Increase of PLK1 and decrease of PLK3 are associated with the developments and metastases of many types of human malignant tumors; however, the situations of PLKs in prion diseases are less understood. Using Western blots and immunohistochemical and immunofluorescent assays, marked increase of PLK1 and decrease of PLK3 were observed in the brains of scrapie strain 263K-infected hamsters, presenting obviously a time-dependent phenomenon along with disease progression. Similar alterations of PLKs were also detected in a scrapie infectious cell line SMB-S15. Both PLK1 and PLK3 were observed in neurons by confocal microscopy. Accompanying with the changes of PLKs in the brains of 263K-infected hamsters, Cdc25C and its phosphorylated forms (p-Cdc25C-Ser198 and p-Cdc25C-Ser216) were significantly down-regulated, whereas Cyclin B1 and PCNA were obviously up-regulated, while phospho-histone H3 remained almost unchanged. Moreover, exposure of the cytotoxic peptide PrP106-126 on the primary cultured cortical neuron cells induced similar changes of cellular PLKs and some cell cycle-related proteins, such as Cdc25C and its phosphorylated forms, phospho-histone H3. Those results illustrate obviously aberrant expressions of cell cycle regulatory proteins in the prion-infected neurons, which may lead to the cell cycle arrest at M phase. Possibly due to the ill-regulation of some key cell cycle events during prion infection, together with the fact that neurons are unable to complete mitosis, the cell cycle reentry in prion-infected neurons is definitely abortive, which may lead to neuron apoptosis and neuron degeneration.

The over-expression of Pim-2 promote the tumorigenesis of prostatic carcinoma through phosphorylating eIF4B

BACKGROUND

Cell experiments have found Pim-2 may take part in the tumorigenesis of prostatic carcinoma (PCA). More direct evidences are needed, and the detailed anti-apoptotic mechanism of Pim-2 in PCA cells is still unknown.

METHODS

Pim-2 expression levels were compared between benign prostatic hyperplasia (BPH) tissues and PCA tissues using real time PCR and Western blot, respectively. Then Pim-2 expression levels were detected in PCA cell lines DU-145 and LNCaP, as well as in nontumorous prostatic epithelial cell lines RWPE-1 and PNT1a, using real time PCR and Western blot, respectively. The co-expression of Pim-2 and eukaryotic initiation factor 4B (eIF4B) was examined by immunofluorescence cytochemistry using laser scanning confocal microscope. Finally, Pim-2 SiRNA was transfected into DU-145 cells and Pim-2 was transfected into RWPE-1 cells, and the level of Pim-2 and phosphorylated eukaryotic initiation factor 4B (p-eIF4B) were detected, as well as the apoptosis rate.

RESULTS

The Pim-2 mRNA and protein level were significantly higher in PCA tissues than those in BPH tissues. The Pim-2 mRNA and protein level in DU-145 and LNCaP cells were significantly higher than those in RWPE-1 and PNT1a cells. Pim-2 and eIF4B could co-express in DU-145 cells. Pim-2 level determined the phosphorylation level of eIF4B and the apoptosis rate of prostatic cells. The higher Pim-2 expressed, the more eIF4B phosphorylated, then the less cell got apoptosis, and vice versa.

CONCLUSION

Pim-2 was over-expressed in PCA cell lines and tissues. It may inhibit the apoptosis of PCA cells through phosphorylating eIF4B, thus promote the tumorigenesis of PCA.

Osteoarthritis pain mechanisms: basic studies in animal models

OBJECTIVE

Osteoarthritis (OA) is a complex and painful disease of the whole joint. At present there are no satisfying agents for treating OA. To promote OA research and improved treatment, this review summarizes current preclinical evidence on the development of OA.

METHODS

Preclinical OA research was searched and key findings are summarized and commented.

RESULTS

Mechanisms of OA-associated pain have been studied in rodent knee OA models produced by intra-knee injection of the chondrocyte glycolytic inhibitor mono-iodoacetate (MIA), surgery, or spontaneous development in some species. These models are clinically relevant in terms of histological damage and functional changes, and are used to study mechanisms underlying mechanical, thermal, ambulatory, body weight supporting-evoked, and ongoing OA pain. Recent peripheral, spinal, and supraspinal biochemical and electrophysiological studies in these models suggest that peripheral pro-inflammatory mediators and neuropeptides sensitize knee nociceptors. Spinal cytokines and neuropeptides promote OA pain, and peripheral and spinal cannabinoids inhibit OA pain respectively through cannabinoid-1 (CB1) and CB1/CB2 receptors. TRPV1 and metalloproteinases contribute and supraspinal descending facilitation of 5-hydroxytryptamine (5-HT)/5-HT 3 receptors may also contribute to OA pain. Conditioned place preference tests demonstrate that OA pain induces aversive behaviors, suggesting the involvement of brain. During OA, brain functional connectivity is enhanced, but at present it is unclear how this change is related to OA pain.

CONCLUSION

Animal studies demonstrate that peripheral and central sensitization contributes to OA pain, involving inflammatory cytokines, neuropeptides, and a variety of chemical mediators. Interestingly, brainstem descending facilitation of 5-HT/5-HT3 receptors plays a role OA pain.

DAMGO in the central amygdala alleviates the affective dimension of pain in a rat model of inflammatory hyperalgesia

Pain has sensory-discriminative and emotional-affective dimensions. Recent studies show that the affective component can be assessed with a conditioned place avoidance (CPA) test. We hypothesized that systemic morphine before a post-conditioning test would more potently attenuate the affective aspect compared to the sensory component and that [d-Ala2-N-Me-Phe4, Gly-ol5]-enkephalin (DAMGO), a μ-selective opioid receptor agonist, injected into the central nucleus of the amygdala (CeA) would reduce established CPA. A rat model of inflammatory pain, produced by a complete Freund adjuvant (CFA) injection into the hind paw, was combined with a CPA test. Three experiments were performed on adult male Sprague-Dawley rats. Systemic morphine (0.5 or 1.0mg/kg) in Experiment 1, intrathecal (i.t.) morphine (2.5 μg/rat) in Experiment 2, and intra-CeA DAMGO (7.7-15.4 ng/0.4 μl) in Experiment 3 were given to CFA-injected rats (n=6-8/group) prior to a post-conditioning test. Saline-injected rats were used as control. Time spent in a pain-paired compartment was recorded twice, before conditioning and after a post-conditioning test. Paw withdrawal latency (PWL) to a noxious thermal stimulus was measured before experiment at day-1 and after the post-conditioning test; hyperalgesia was defined as a decrease in PWL. The data showed that CFA-injected rats had significantly negative CPA compared to those of saline-injected rats (P<0.05). Low-dosage systemic morphine significantly (P<0.05) reduced CFA-induced CPA but had no effect on PWL. I.t. morphine did not inhibit the display of CPA but significantly increased PWL, suppressing hyperalgesia (P<0.05). Intra-CeA DAMGO significantly inhibited the display of CPA compared to saline (P<0.05) but had no effect on PWL. The data demonstrate that morphine attenuates the affective component more powerfully than it does the sensory and suggests that the sensory and the emotional-affective dimensions are underpinned by different mechanisms.

Celastrol protects kidney against ischemia-reperfusion-induced injury in rats

BACKGROUND

Ischemia-reperfusion (IR) causes various damages in renal tissues, which is exacerbated by hypoxia-induced excessive inflammation and deteriorates the prognosis of patients after kidney surgery. Celastrol is a potent inflammation inhibitor that has little toxicity. In this report, we investigated whether celastrol protects against IR-induced renal injury in rats.

MATERIALS AND METHODS

Renal IR injury was induced by occlusion of the bilateral renal pedicles for 45 min followed by reperfusion for 6 h. Celastrol or vehicle solution was intraperitoneally injected 30 min before renal ischemia, respectively. Renal histology, function, and pro-inflammatory cytokines and mediators were assessed. The effect of celastrol on nuclear translocation of nuclear factor kappa B (NF-κB) was also measured.

RESULTS

Celastrol significantly suppressed elevation of the renal function markers and the lipid peroxidation level, alleviated renal tubular damage, and decreased the levels of tumor necrosis factor-α, interleukin-1β, and monocyte chemotactic protein-1 (MCP-1) messenger RNA in kidney caused by IR. Moreover, celastrol prevented IR-induced expression of pro-inflammatory mediators, which was associated with suppression of nuclear translocation of NF-κB subunit p65.

CONCLUSIONS

Celastrol ameliorated the acute kidney injury caused by IR, which was associated with inhibiting local NF-κB activation and inflammation. Our findings suggest that celastrol could be useful for preventing IR-induced renal injury.

Abnormally upregulated αB-crystallin was highly coincidental with the astrogliosis in the brains of scrapie-infected hamsters and human patients with prion diseases

αB-crystallin is a member of the small heat shock protein family constitutively presenting in brains at a relatively low level. To address the alteration of αB-crystallin in prion disease, the αB-crystallin levels in the brains of scrapie agent 263 K-infected hamsters were analyzed. The levels of αB-crystallin were remarkably increased in the brains of 263 K-infected hamsters, showing a time-dependent manner along with incubation time. Immunohistochemical (IHC) and immunofluorescent (IFA) assays illustrated more αB-crystallin-positive signals in the regions of the cortex and thalamus containing severe astrogliosis. Double-stained IFA verified that the αB-crystallin signals colocalized with the enlarged glial fibrillary acidic protein-positive astrocytes, but not with neuronal nuclei-positive cells. IHC and IFA of the serial brain sections of infected hamsters showed no colocalization and correlation between PrP(Sc) deposits and αB-crystallin increase. Moreover, increased αB-crystallin deposits were observed in the brain sections of parietal lobe of a sporadic Creutzfeldt-Jakob disease (sCJD) case, parietal lobe and thalamus of a G114V genetic CJD case, and thalamus of a fatal family insomnia (FFI) case, but not in a parietal lobe of FFI where only very mild astrogliosis was addressed. Additionally, the molecular interaction between αB-crystallin and PrP was only observed in the reactions of recombinant proteins purified from Escherichia coli, but not either in that of brain homogenates or in that of the cultured cell lysates expressing human PrP and αB-crystallin. Our data indicate that brain αB-crystallin is abnormally upregulated in various prion diseases, which is coincidental with astrogliosis. Direct interaction between αB-crystallin and PrP seems not to be essential during the pathogenesis of prion infection.

Brain microglia were activated in sporadic CJD but almost unchanged in fatal familial insomnia and G114V genetic CJD

Background

Microglial activations have been described in different subtypes of human prion diseases such as sporadic Creutzfeldt-Jakob disease (CJD), variant CJD, Kuru and Gerstmann-Sträussler-Scheinker disease (GSS). However, the situation of microglia in other genetic prion diseases such as fatal familial insomnia (FFI) and familial CJD remains less understood. The brain microglia was evaluated comparatively between the FFI, G114V and sCJD cases in the study.

Methods

Specific Western blots, immunohistochemical and immunofluorescent assays were used to detect the changes of microglia and ELISA tests were used for levels of inflammatory cytokines.

Results

Western blots, immunohistochemical and immunofluorescent assays illustrated almost unchanged microglia in the temporal lobes of FFI and G114V gCJD, but obviously increased in those of sCJD. The Iba1-levels maintained comparable in six different brain regions of FFI and G114V cases, including thalamus, cingulate gyrus, frontal cortex, parietal cortex, occipital cortex and temporal cortex. ELISA tests for inflammatory cytokines revealed significantly up-regulated IL-1β, IL-6 and TNF-α in the brain homogenates from sCJD, but not in those from FFI and G114V gCJD.

Conclusion

Data here demonstrates silent brain microglia in FFI and G114V gCJD but obviously increased in sCJD, which reflects various pathogenesis of different human prion diseases subtypes.

Development of inclusion complex of brinzolamide with hydroxypropyl-β-cyclodextrin

Glaucoma is an accumulative optic neuropathy resulted from increasing intraocular pressure. Brinzolamide (BRZ) is a kind of carbonic anhydrase inhibitors for glaucoma treatment. In this study, brinzolamide-hydroxypropyl-β-cyclodextrin (BRZ-HP-β-CD) inclusion complex was prepared by solvent evaporation method to improve the solubility of BRZ and enhance the therapeutic effect of BRZ. The formation of the inclusion complex was confirmed by Fourier transform infrared spectroscopy, differential scanning calorimeter and nuclear magnetic resonance spectroscopy. The solubility of BRZ increased about 10-fold after the formation of the BRZ-HP-β-CD inclusion complex. The in vitro corneal accumulative permeability of the inclusion complex increased 2.91-fold compared to the commercial available formulation (AZOPT(®)). In addition, BRZ-HP-β-CD inclusion complex (0.5% BRZ) had an equivalent efficiency of lowering intraocular pressure with AZOPT(®) (1% BRZ) in vivo. These results identified the BRZ-HP-β-CD inclusion complex might have a promising future as a novel formulation of BRZ for glaucoma treatment.

Mouse lymphatic endothelial cell targeted probes: anti-LYVE-1 antibody-based magnetic nanoparticles

Purpose

To investigate the specific targeting property of lymphatic vessel endothelial hyaluronan receptor-1 binding polyethylene glycol-coated ultrasmall superparamagnetic iron oxide (LYVE-1-PEG-USPIO) nanoparticles to mouse lymphatic endothelial cells (MLECs).

Methods

A ligand specific target to lymphatic vessels was selected by immunohistochemical staining on the sections of a Lewis subcutaneous transplanted tumor. The z-average hydrodynamic diameter (HD), zeta potential, and the relaxivity of PEG-USPIO and LYVE-1-PEG-USPIO nanoparticles were determined with a laser particle analyzer and magnetic resonance T₂ spin echo sequence, respectively. Prussian blue staining and transmission electron microscopy (TEM) of nanoparticle labeled cells were performed to determine the nanoparticles’ binding form. Magnetic resonance imaging (MRI) was performed in vitro to evaluate the signal enhancement on the T₂ spin echo sequence of the nanoparticle labeled cells. The iron content of the labeled cells after the Prussian blue staining and MRI scanning was determined by atomic absorption spectroscopy (AAS).

Results

The anti-LYVE-1 antibody was used as the specific ligand to synthesize the target probe to the MLECs. The mean z-average HDs of the LYVE-1-PEG-USPIO and PEG-USPIO nanoparticles were 57.42 ± 0.31 nm and 47.91 ± 0.73 nm, respectively, and the mean zeta potentials of the LYVE-1-PEG-USPIO and PEG-USPIO nanoparticles were 12.38 ± 4.87 mV and 2.57 ± 0.83 m V, respectively. The relaxivities of the LYVE-1-PEG-USPIO and PEG-USPIO nanoparticles were 185.48 mM⁻¹s⁻¹ and 608.32 mM⁻¹s⁻¹. Cells binding nanoparticles were visualized as blue granules in the Prussian blue staining. The TEM results of the labeled cells showed the specific localization of nanoparticles. The AAS results of labeled cells after the Prussian blue staining and MRI scanning showed that the LYVE-1-PEG-USPIO nanoparticles had good binding selectivity for MLECs. MRI results indicated that the PEG-USPIO and LYVE-1-PEG-USPIO nanoparticles could generate contrast on T₂-weighted imaging, and the correlation between R₂ and the iron content of the labeled cells was significantly positive.

Conclusion

This study demonstrated that LYVE-1-PEG-USPIO nanoparticles might potentially be used as an MRI contrast agent for targeting MLECs, and the magnetic properties of LYVE-1-PEG-USPIO nanoparticles were suitable for MRI.

Radiation dose study of 64-slice spiral CT coronary angiography: a paired design

To compare image noise and radiation dose differences between prospective and retrospective ECG-gated computed tomography (CT) coronary artery imaging with 64-slice spiral CT (64-MSCT) in a paired design. Prospective and retrospective ECG-gated CT coronary angiography was performed among 20 out-patients with suspected coronary artery diseases. If one protocol failed, chose the other instead. The differences in effective dose (ED), image noise, contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) between the two scan protocols were compared. Usual causes of failures were analysed for each. The average ED of retrospective and prospective protocol was 21.6±2 and 6.0±1.2 mSv, respectively. There was a significant statistical difference in the two protocols (p < 0.05 and 6.16e(-14)). The image noise and SNR between the two protocols made no differences (p=0.71, 0.26, >0.05). The average image noise and SNR of retrospective and prospective protocol were (27.95±2.82, 28.66±2.9) and (12.15±1.83, 10.9±1.17). The CNR of retrospective and prospective protocol was (14.52±1.59) and (17.3±2.09), respectively. There was a statistical difference (p < 0.05 and 0.045). The prospective protocol can lower the ED of 64-MSCT a lot than the retrospective protocol. The image noise and SNR made no differences, whereas the prospective protocol gave a better CNR result.

Flotillin-1 mediates PrPc endocytosis in the cultured cells during Cu²⁺ stimulation through molecular interaction

Flotillins are membrane association proteins consisting of two homologous members, flotillin-1 (Flot-1) and flotillin-2 (Flot-2). They define a clathrin-independent endocytic pathway in mammal cells, which are also distinct from some other endocytosis mechanisms. The implicated cargoes of the flotillin-dependent pathway are mainly some GPI-anchored proteins, such as CD59 and Thy-1, which positionally colocalize with flotillins at the plasma membrane microdomains. To see whether flotillins are involved in the endocytosis of PrP(C), the potential molecular interaction between PrP(C) and flotillins in a neuroblastoma cell line SK-N-SH was analyzed. Co-immunoprecipitation assays did not reveal a detectable complex in the cell lysates of a normal feeding situation. After stimulation of Cu(2+), PrP(C) formed a clear complex with Flot-1, but not with Flot-2. Immunofluorescent assays illustrated that PrP(C) colocalized well with Flot-1, and the complexes of PrP(C)-Flot-1 shifted from the cell membrane to the cytoplasm along with the treatment of Cu(2+). Down-regulating the expression of Flot-1 in SK-N-SH cells by Flot-1-specific RNAi obviously abolished the Cu(2+)-stimulated endocytosis process of PrP(C). Moreover, we also found that in the cell line human embryonic kidney 293 (HEK293) without detectable PrP(C) expression, the distribution of cellular Flot-1 maintained almost unchanged during Cu(2+) treatment. Cu(2+)-induced PrP(C)-Flot-1 molecular interaction and endocytosis in HEK293 cells were obtained when expressing wild-type human PrP (PrP(PG5)), but not in the preparation expressing octarepeat-deleted PrP (PrP(PG0)). Our data here provide direct evidences for the molecular interaction and endocytosis of PrP(C) with Flot-1 in the presence of copper ions, and the octarepeat region of PrP(C) is critical for this process, which strongly indicates that the Flot-1-dependent endocytic pathway seems to mediate the endocytosis process of PrP(C) in the special situation.

Transition to persistent orofacial pain after nerve injury involves supraspinal serotonin mechanisms

The orofacial region is a major focus of chronic neuropathic pain conditions characterized by primary hyperalgesia at the site of injury and secondary hyperalgesia outside the injured zone. We have used a rat model of injury to the maxillary branch (V2) of the trigeminal nerve to produce constant and long-lasting primary hyperalgesia in the V2 territory and secondary hyperalgesia in territories innervated by the mandibular branch (V3). Our findings indicate that the induction of primary and secondary hyperalgesia depended on peripheral input from the injured nerve. In contrast, the maintenance of secondary hyperalgesia depended on central mechanisms. The centralization of the secondary hyperalgesia involved descending 5-HT drive from the rostral ventromedial medulla and the contribution of 5-HT3 receptors in the trigeminal nucleus caudalis (Vc), the homolog of the spinal dorsal horn. Electrophysiological studies further indicate that after nerve injury spontaneous responses and enhanced poststimulus discharges in Vc nociresponsive neurons were time-dependent on descending 5-HT drive and peripheral input. The induction phase of secondary hyperalgesia involved central sensitization mechanisms in Vc neurons that were dependent on peripheral input, whereas the maintenance phase of secondary hyperalgesia involved central sensitization in Vc neurons conducted by a delayed descending 5-HT drive and a persistence of peripheral inputs. Our results are the first to show that the maintenance of secondary hyperalgesia and underlying central sensitization associated with persistent pain depend on a transition to supraspinal mechanisms involving the serotonin system in rostral ventromedial medulla-dorsal horn circuits.

[Analysis of the expressions of alphaB-crystallin in the brain tissues of agent 263K-infected hamsters at terminal stage]

alphaB-crystallin is a member of the sHSP (Small heat shock protein) family, which plays an impor tant role in multiple neurodegeneration diseases. To give insight into the possible alternation and the role of aB-crystallin in prion disease, the alphaB-crystallin levels in the brain tissues of agent 263K-infected hamsters were evaluated. Western blots and IHC revealed that at the terminal stages of the diseases, the levels of alphaB-crystallin were increased up to 3-fold in the brain tissues of scrapie infected 263K hamsters compared with normal controls. Immunofluorescent assays revealed that the up-regulated alphaB-crystallin was mainly observed in astrocytes, but not in neurons. The co-localization between alphaB-crystallin and abnormal deposition of PrPsc in the brain tissues of the scrapie infected hamsters was not observed. The study may provide a foundation for further revealing the potential role of alphaB-crystallin in prion disease.

Development of polymeric nanocarrier system for early detection and targeted therapeutic treatment of peri-implant osteolysis

BACKGROUND

Extensive research has implicated inflammation as a necessary and causative factor in the development of peri-implant osteolysis, suggesting that such an inflammatory response is the sentinel event for the process. The potential to impact the clinical course of this condition is hampered by the lack of an effective medical therapy, as well as a limited ability for early detection prior to radiographically evident osteolysis. Advances in nanotechnology have allowed for the production of engineered water-soluble nanocarriers, which exploit changes in the microvascular architecture for selective distribution to inflamed tissues. Evaluation of the uptake of the nanocarriers in sites of inflammation has elucidated a novel mechanism of cellular uptake and retention of these particles.

PURPOSE

The current review discusses the development of a novel, biocompatible, water-soluble nanocarrier utilizing copolymers of N-(2-hydroxypropyl)methacrylamide (HPMA), conjugated to imaging and therapeutic agents for the detection and targeted treatment of inflammatory conditions.

METHODS

We performed Medline searches for the terms "periprosthetic osteolysis," "murine osteolysis model," "HPMA osteolysis," and "HPMA inflammation." These searches identified 631, 306, 1, and 6 articles, respectively. These were then manually searched for articles relevant to the development of mouse models for inflammatory osteolysis and the use of HPMA copolymer technology in mouse models of inflammation.

RESULTS

Promising results in a small animal model of osteolysis have demonstrated the capability for detection prior to the development of bone loss, and have highlighted the utility of nanocarriers for selective drug delivery to the affected tissues.

CONCLUSIONS

Challenges to the clinical translation of HPMA nanocarriers in peri-implant osteolysis remain, and the future research directions necessary for human clinical application are reviewed.

[Value of multidetector CT on aiding intraoperative judgement of serosal invasion of gastric cancer]

OBJECTIVE

To explore the value of multidetector CT on aiding intraoperative judgement of serosal invasion of gastric cancer.

METHODS

Clinical data of 206 cases of gastric cancer undergoing radical surgery in the First Hosptial of China Medical University from August 2009 to June 2011 were analyzed retrospectively. Preoperative CT findings and intraoperative judgement of serosal invasion in gastric cancer were compared with pathological results in order to investigate their values.

RESULTS

The sensitivity and specificity of preoperative CT findings and intraoperative judgement of serosal invasion were 88.5%, 81.5% and 98.9%, 61.3%, respectively. The accuracy of preoperative CT in diagnosing serosal invasion was higher than that of intraoperative judgement, while the difference was not statistically significant (84.5% vs. 77.2%, P=0.060). The rates of serosal invasion of normal type, reactive type, nodular type, tendonoid type and color-diffused type were 0 (0/29), 2.5% (1/40), 40.5% (15/37), 59.2% (29/49), and 82.4% (42/51) respectively. The accuracy of preoperative CT in diagnosing serosal invasion of gastric cancer with tendonoid type was higher than that of intraoperative judgement, and the difference was statistically significant (61.2% vs. 87.8%, P=0.002).

CONCLUSIONS

Multidetector CT plays an important role in aiding intraoperation judgement of serosal invasion of gastric cancer. For gastric cancer with tendonoid and color-diffused macroscopic serosal appearance, surgeons should pay attention to the value of preoperative CT findings.

Chemokine signaling involving chemokine (C-C motif) ligand 2 plays a role in descending pain facilitation

OBJECTIVE

Despite accumulating evidence on a role of immune cells and their associated chemicals in mechanisms of pain, few studies have addressed the potential role of chemokines in the descending facilitation of persistent pain. The present study was undertaken to test the hypothesis that the chemokine (C-C motif) ligand 2 (CCL2) (commonly known as monocyte chemoattractant protein-1) signaling in the rostral ventromedial medulla (RVM), a pivotal structure in brainstem pain modulatory circuitry, is involved in descending pain facilitation in rats.

METHODS

An L5 spinal nerve ligation (SNL) was produced in rats under pentobarbital anesthesia. Western blot and immunohistochemistry were used to detect the expression levels of CCL2 and CCL2 receptor (CCR2), and examine their distributions compared with the neuronal marker NeuN as well as glial markers glial fibrillary acidic protein (GFAP, astroglial) and CD11b (microglial), respectively.

RESULTS

SNL induced an increase in CCL2 expression in the RVM, and this returned to the control level at 4 weeks after injury. The induced CCL2 colocalized with NeuN, but not with GFAP and CD11b. CCR2 was also upregulated by SNL in the RVM, and this increase lasted for at least 4 weeks. CCR2 was colocalized with CD11b but not GFAP. Few RVM neurons also exhibited CCR2 staining. Neutralizing CCL2 with an anti-CCL2 antibody (0.2-20 ng) or injecting RS-102895 (0.1-10 pmol), a CCR2b chemokine receptor antagonist, into the RVM on day 1 after SNL, significantly attenuated the established thermal and mechanical hypersensitivity. In addition, injection of recombinant rat CCL2 (0.03-3 pmol) into the RVM induced dose-dependent hyperalgesia, which was prevented by pretreatment with RS-102895 (10 pmol). Interleukin-1β (IL-1β), a potent inducer of neuronal CCL2, was also selectively upregulated in RVM reactive astrocytes. Injection of IL-1β (120 fmol) into the RVM induced behavioral hyperalgesia, which was blocked by RS-102895 (10 pmol). However, an IL-1 receptor antagonist (3 pmol) did not prevent CCL2 (3 pmol)-induced hyperalgesia. These results suggest that the effect of CCL2 is downstream to IL-1β signaling.

CONCLUSION

The IL-1β and CCL2-CCR2 signaling cascades play a role in neuron-glia-cytokine interactions and the descending facilitation of neuropathic pain.

Electroacupuncture alleviates affective pain in an inflammatory pain rat model

Pain has both sensory-discriminative and emotional-affective dimensions. Previous studies demonstrate that electroacupuncture (EA) alleviates the sensory dimension but do not address the affective. An inflammatory pain rat model, produced by a complete Freund adjuvant (CFA) injection into the hind paw, was combined with a conditioned place avoidance (CPA) test to determine whether EA inhibits spontaneous pain-induced affective response and, if so, to study the possibility that rostral anterior cingulate cortex (rACC) opioids underlie this effect. Male Sprague-Dawley rats (250-275 g, Harlan) were used. The rats showed place aversion (i.e. affective pain) by spending less time in a pain-paired compartment after conditioning than during a preconditioning test. Systemic non-analgesic morphine (0.5 and 1.0 mg/kg, i.p.) inhibited the affective reaction, suggesting that the affective dimension is underpinned by mechanisms different from those of the sensory dimension of pain. Morphine at 0.5 and at 1 mg/kg did not induce reward. Rats given EA treatment before pain-paired conditioning at GB 30 showed no aversion to the pain-paired compartment, indicating that EA inhibited the affective dimension. EA treatment did not produce reward or aversive effect. Intra-rACC administration of D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr amide (CTOP), a selective mu opioid receptor antagonist, but not norbinaltorphimine (nor-BNI), a selective kappa opioid receptor antagonist, blocked EA inhibition of the affective dimension. These data demonstrate that EA activates opioid receptors in the rACC to inhibit pain-induced affective responses and that EA may be an effective therapy for both the sensory-discriminative and the affective dimensions of pain.

[Study on the correlation between membrane protein Flotillin-1 and PrPc endocytosis]

OBJECTIVE

To explore whether the membrane-associated protein Flotillin-1 has relationship with endocytosis of PrPc.

METHODS

The expression of Flotillin-1 in different cell lines was detected with the method of Western Blot; the interaction between Flotillin-1 and PrPc in Cells which were treated with copper ions was observed using immunoprecipitation method.

RESULTS

(1) Flotillin-1 was widely expressed in many cell lines without significant difference in the amounts of expression level; (2) Only in the appearance of copper ions, the protein complexes of PrPc and Flotillin-1 can be detected with the method of IP, which were related to copper ions concentration and processing time.

CONCLUSION

The membrane-associated protein Flotillin-1 has the relationship with the endocytosis of PrPc.

Trigeminal-rostral ventromedial medulla circuitry is involved in orofacial hyperalgesia contralateral to tissue injury

BACKGROUND

Our previous studies have shown that complete Freund's adjuvant (CFA)-induced masseter inflammation and microinjection of the pro-inflammatory cytokine interleukin-1β (IL-1β) into the subnucleus interpolaris/subnucleus caudalis transition zone of the spinal trigeminal nucleus (Vi/Vc) can induce contralateral orofacial hyperalgesia in rat models. We have also shown that contralateral hyperalgesia is attenuated with a lesion of the rostral ventromedial medulla (RVM), a critical site of descending pain modulation. Here we investigated the involvement of the RVM-Vi/Vc circuitry in mediating contralateral orofacial hyperalgesia after an injection of CFA into the masseter muscle.

RESULTS

Microinjection of the IL-1 receptor antagonist (5 nmol, n=6) into the ipsilateral Vi/Vc attenuated the CFA-induced contralateral hyperalgesia but not the ipsilateral hyperalgesia. Intra-RVM post-treatment injection of the NK1 receptor antagonists, RP67580 (0.5-11.4 nmol) and L-733,060 (0.5-11.4 nmol), attenuated CFA-induced bilateral hyperalgesia and IL-1β induced bilateral hyperalgesia. Serotonin depletion in RVM neurons prior to intra-masseter CFA injection prevented the development of contralateral hyperalgesia 1-3 days after CFA injection. Inhibition of 5-HT(3) receptors in the contralateral Vi/Vc with direct microinjection of the select 5-HT(3) receptor antagonist, Y-25130 (2.6-12.9 nmol), attenuated CFA-induced contralateral hyperalgesia. Lesions to the ipsilateral Vc prevented the development of ipsilateral hyperalgesia but did not prevent the development of contralateral hyperalgesia.

CONCLUSIONS

These results suggest that the development of CFA-induced contralateral orofacial hyperalgesia is mediated through descending facilitatory mechanisms of the RVM-Vi/Vc circuitry.