Inhibition of Immunoproteasome Attenuates NLRP3 Inflammasome Response by Regulating E3 Ubiquitin Ligase TRIM31

Excessive secretion of pro-inflammatory cytokines leads to the disruption of intestinal barrier in inflammatory bowel disease (IBD). The inflammatory cytokine tumor necrosis factor alpha (TNFα) induces the assembly of the NLRP3 inflammasome, resulting in the augmented secretion of inflammatory cytokines implicated in the pathogenesis of inflammatory bowel disease (IBD). TNFα has also been known to induce the formation of immunoproteasome (IP), which incorporates immunosubunits LMP2, LMP7, and MECL-1. Inhibition of IP activity using the IP subunit LMP2-specific inhibitor YU102, a peptide epoxyketone, decreased the protein levels of NLRP3 and increased the K48-linked polyubiquitination levels of NLRP3 in TNFα-stimulated intestinal epithelial cells. We observed that inhibition of IP activity caused an increase in the protein level of the ubiquitin E3 ligase, tripartite motif-containing protein 31 (TRIM31). TRIM31 facilitated K48-linked polyubiquitination and proteasomal degradation of NLRP3 with an enhanced interaction between NLRP3 and TRIM31 in intestinal epithelial cells. In addition, IP inhibition using YU102 ameliorated the symptoms of colitis in the model mice inflicted with dextran sodium sulfate (DSS). Administration of YU102 in the DSS-treated colitis model mice caused suppression of the NLRP3 protein levels and accompanied inflammatory cytokine release in the intestinal epithelium. Taken together, we demonstrated that inhibiting IP under inflammatory conditions induces E3 ligase TRIM31-mediated NLRP3 degradation, leading to attenuation of the NLRP3 inflammatory response that triggers disruption of intestinal barrier.

Reduced secretion of LCN2 (lipocalin 2) from reactive astrocytes through autophagic and proteasomal regulation alleviates inflammatory stress and neuronal damage

LCN2/neutrophil gelatinase-associated lipocalin/24p3 (lipocalin 2) is a secretory protein that acts as a mammalian bacteriostatic molecule. Under neuroinflammatory stress conditions, LCN2 is produced and secreted by activated microglia and reactive astrocytes, resulting in neuronal apoptosis. However, it remains largely unknown whether inflammatory stress and neuronal loss can be minimized by modulating LCN2 production and secretion. Here, we first demonstrated that LCN2 was secreted from reactive astrocytes, which were stimulated by treatment with lipopolysaccharide (LPS) as an inflammatory stressor. Notably, we found two effective conditions that led to the reduction of induced LCN2 levels in reactive astrocytes: proteasome inhibition and macroautophagic/autophagic flux activation. Mechanistically, proteasome inhibition suppresses NFKB/NF-κB activation through NFKBIA/IκBα stabilization in primary astrocytes, even under inflammatory stress conditions, resulting in the downregulation of Lcn2 expression. In contrast, autophagic flux activation via MTOR inhibition reduced the intracellular levels of LCN2 through its pre-secretory degradation. In addition, we demonstrated that the N-terminal signal peptide of LCN2 is critical for its secretion and degradation, suggesting that these two pathways may be mechanistically coupled. Finally, we observed that LPS-induced and secreted LCN2 levels were reduced in the astrocyte-cultured medium under the above-mentioned conditions, resulting in increased neuronal viability, even under inflammatory stress.Abbreviations: ACM, astrocyte-conditioned medium; ALP, autophagy-lysosome pathway; BAF, bafilomycin A1; BTZ, bortezomib; CHX, cycloheximide; CNS, central nervous system; ER, endoplasmic reticulum; GFAP, glial fibrillary acidic protein; GFP, green fluorescent protein; JAK, Janus kinase; KD, knockdown; LCN2, lipocalin 2; LPS, lipopolysaccharide; MACS, magnetic-activated cell sorting; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; MTOR, mechanistic target of rapamycin kinase; NFKB/NF-κB, nuclear factor of kappa light polypeptide gene enhancer in B cells 1, p105; NFKBIA/IκBα, nuclear factor of kappa light polypeptide gene enhancer in B cells inhibitor, alpha; OVEX, overexpression; SLC22A17, solute carrier family 22 member 17; SP, signal peptide; SQSTM1, sequestosome 1; STAT3, signal transducer and activator of transcription 3; TNF/TNF-α, tumor necrosis factor; TUBA, tubulin, alpha; TUBB3/β3-TUB, tubulin, beta 3 class III; UB, ubiquitin; UPS, ubiquitin-proteasome system.

Inhibition of immunoproteasome attenuates NLRP3 inflammasome formation in tumor necrosis factor α-stimulated intestinal epithelial cell

Excessive release of inflammatory cytokines has been considered as a major cause of chronic inflammation, resulting in intestinal barrier disruption that leads to inflammatory bowel disease (IBD). Tumor necrosis factor α (TNFα) is one of the well-known inflammatory cytokines that activates formation of NLRP3 inflammasome, thus resulting in excessive secretion of inflammatory cytokines causing IBD. Although immunoproteasome inhibitors have been reported to inhibit inflammatory cytokine release, immunoproteasome inhibition has not yet been addressed for attenuation of NLRP3 inflammasome activity in intestinal epithelial cell. Here, we observed that NLRP3 inflammasome assembly was attenuated by peptide epoxyketone YU102, a LMP2 subunit immunoproteasome inhibitor, in intestinal epithelial cell. YU102 also inhibited maturation of active caspase-1 and secretion of IL-1β, which are subsequent inflammatory cascade after the formation of NLRP3 inflammasome. Progression of epithelial-mesenchymal transition and increase of cellular permeability, which were induced by TNFα, were also suppressed through inhibition of immunoproteasome. Furthermore, we found that YU102 does not inhibit degradation of IкBα and its following NF-кB activation that leads to transcription of NLRP3. These findings suggest that inhibition of immunoproteasome with YU102 offers a potential therapeutic premise for prevention of TNFα-induced chronic inflammation through attenuation of NLRP3 inflammasome assembly.

Homologous expression and quantitative analysis of T3SS-dependent secretion of TAP-tagged XoAvrBs2 in Xanthomonas oryzae pv. oryzae induced by rice leaf extract

Xanthomonas oryzae pv. oryzae (Xoo) produces a putative effector, XoAvrBs2. We expressed XoAvrBs2 homologously in Xoo with a TAP-tag at the C-terminus to enable quantitative analysis of protein expression and secretion. Addition of rice leaf extracts from both Xoo-sensitive and Xoo-resistant rice cultivars to the Xoo cells induced expression of the XoAvrBs2 gene at the transcriptional and translational levels, and also stimulated a remarkable amount of XoAvrBs2 secretion into the medium. In a T3SS-defective Xoo mutant strain, secretion of the TAPtagged XoAvrBs2 was blocked. Thus, we elucidated the transcriptional and translational expressions of the XoAvrBs2 gene in Xoo was induced in vitro by the interaction with rice and the induced secretion of XoAvrBs2 was T3SSdependent. It is the first report to measure the homologous expression and secretion of XoAvrBs2 in vitro by rice leaf extract. Our system for the quantitative analysis of effector protein expression and secretion could be generally used for the study of host-pathogen interactions.

Differences in microstructural alterations of the hippocampus in Alzheimer disease and idiopathic normal pressure hydrocephalus: a diffusion tensor imaging study

BACKGROUND AND PURPOSE

DTI can be used to assess the degradation of WM tracts by measuring the FA and MD. Decreased FA/increased MD values in the AD hippocampus have been reported by many studies. In contrast, only a few studies reported on hydrocephalus by using the DTI technique. In elderly patients with dementia and with dilated ventricles, it is often difficult to differentiate iNPH from AD with visual measurements on MR imaging. The aim of this study was to investigate the changes of microstructural integrity of the hippocampus in iNPH by using DTI and determining whether this method could be a new diagnostic tool to differentiate iNPH from AD.

MATERIALS AND METHODS

We recruited 43 participants (15 healthy controls, 15 patients with AD, and 13 patients with iNPH). The FA and MD values were measured by using the region-of-interest method in the hippocampal head, body, and tail on both sides. Clinical history, neurologic examination, and neuropsychological assessment were included.

RESULTS

The FA values were the lowest in the patients with AD, the patients with iNPH, and the healthy controls in this order. The MD values were the highest in the same order. These findings were consistent in the 3 subdivisions of the bilateral hippocampal regions. Hippocampal volume was not different between patients with iNPH and AD.

CONCLUSIONS

The microstructural alterations of the hippocampus were more sensitive than the volumetric changes in AD and iNPH. DTI analysis might be a useful tool for discriminating AD from iNPH.

Endometrial stromal sarcomas: A retrospective analysis of 28 patients, single center experience for 20 years

16053

Background: Little is known about the pathogenesis, risk factors, optimal therapy or outcomes of endometrial stromal sarcoma (ESS). The aim of this study is to evaluate the behavior of ESS in relation to its clinical and pathogenic features and to find the better treatment strategy. Methods: A retrospective analysis was performed of 28 patients with histologically proven ESS treated at our institution between 1987 and 2006. Results: The median follow-up time was 54.7±63.1 months and 5-year survival rate was 82.0%. 16 (57.1%) patients were referred to our institution from private clinics for further treatment of the ESS. They were previously undergone either hysterectomy, myomectomy, or hysteroscopy for presumed benign gynecological conditions. 22 patients (81.5%) showed low grade and 5 patients (18.5%) showed high grade disease. A univariate analysis revealed that histologic grade according to mitotic count is associated with longer survival (p=0.004). However, among those with low grade tumor, 5/20 patients (25%) had recurrence and 2/21 (9.5%) had distant metastasis during the follow-up period. Except for 2 cases, 26 patients with ESS had hysterectomy for their primary treatment. Adjuvant treatment after surgery was performed in 14/26 cases (53.8%). Hormone therapy by progesterone, chemotherapy and/or radiotherapy individually did not influence the overall survival of the patients. However, postoperative adjuvant therapy group regardless of the treatment modality was associated with relatively increased overall survival when compared to the surgery only group (p=0.054). Conclusions: Differential diagnosis of ESS from other benign gynecologic diseases before surgery is a difficult problem. Furthermore, it is advised that postoperative adjuvant therapy should be performed after hysterectomy to prevent recurrence or distant metastasis.

No significant financial relationships to disclose.

Instability driven fragmentation of nanoscale fractal islands

Formation and evolution of fragmentation instabilities in fractal islands, obtained by deposition of silver clusters on graphite, are studied. The fragmentation dynamics and subsequent relaxation to the equilibrium shapes are controlled by the deposition conditions and cluster composition. Sharing common features with other materials' breakup phenomena, the fragmentation instability is governed by the length-to-width ratio of the fractal arms.

Preventive effect of germanium dioxide on the inhibition of gap junctional intercellular communication by TPA

Gap junctional intercellular communication (GJIC) is thought to be essential for maintaining cellular homeostasis and growth control. In order to detect any protective agent against tumor formation, we examined the anticarcinogenic effect of a germanium dioxide (GeO(2)) using a model system of GJIC in F344 rat liver epithelial cells, named WB cells. 12-O-tetradecanoylphorbol-13-acetate (TPA), known as tumor promoters, inhibited GJIC in the epithelial cells as determined by the scrape loading/dye transfer (SL/DT) assay. And GeO(2) recovered this inhibition of GJIC. Immunostaining of connexin 43 (Cx43) protein in WB cells indicated that TPA caused a loss of Cx43 protein from the cell membranes. However, GeO(2) treatment showed re-appearance of Cx43 protein on the membrane. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blots were analyzed to determine whether the test compounds might have altered the steady-state levels of gap junction mRNA and/or connexin protein levels or phosphorylation. The inhibition of GJIC by TPA in WB cells was correlated with the hyperphosphorylation of Cx43 as measured by mobility shifts of the western blot bands of Cx43. TPA induced hyperphosphorylation of Cx43 protein, while GeO(2) appeared to partially block this hyperphosphorylation. Here, we showed that pre- and co-incubation with GeO(2) in TPA-treated WB-cells abolished down-regulation of GJIC by TPA. These data suggest that GeO(2) may inhibit tumor promotion by enhancing GJIC.

The expression of pseudogene cyclin D2 mRNA in the human ovary may be a novel marker for decreased ovarian function associated with the aging process

PURPOSE

Our purpose was to investigate the expression pattern of cyclin D2 and pseudogene cyclin D2 mRNA in the human ovary with age.

METHODS

After extraction of the total RNA from ovarian tissues of 23 premenopausal patients, cyclin D2 and pseudogene cyclin D2 mRNAs were measured by the reverse transcription-polymerase chain reaction technique using cyclin D2 and pseudogene cyclin D2 specific primers. Analysis of the cyclin D2 and pseudogene cyclin D2 mRNA expression pattern with age and correlation analysis were carried out.

RESULTS

A 489-bp cyclin D2 band and a 441-bp pseudogene cycin D2 mRNA band were detected in the human ovarian tissue. While cyclin D2 mRNA expression showed a decreasing tendency with age (P = 0.17), pseudogene cyclin D2 mRNA expression increased with age (P < 0.05). Pseudogene cyclin D2 mRNA expression showed a negative correlation with cyclin D2 mRNA (R = -0.35, P < 0.03).

CONCLUSION

The expression of pseudogene cyclin D2 mRNA in the human ovary increases with age, which may be a novel marker for decreased ovarian function associated with the aging process.

Changes in gallbladder motility in gastrectomized patients

OBJECTIVES

Gastric resection may predispose gallstone formation. However, the mechanism has not been clearly understood. To evaluate the relationship between gastric resection and gallstone formation, we compared gallbladder(GB) motility in gastrectomized patients and control subjects.

METHODS

We compared the GB volume and ejection fraction of the 46 gastrectomized patients with 37 healthy controls using real time ultrasonography.

RESULTS

GB volume increased significantly in the gastrectomized group in fasting (30.2 +/- 13.9 ml). The GB volume after a fatty meal was greater in the gastrectomized group (12.6 +/- 6.4 ml) than in the control group (4.3 +/- 3.3 ml) (p < 0.01). A significant reduction of ejection fraction was found in gastrectomized patients (56.9 +/- 13.0%) in comparison with the control group (75.5 +/- 16.1%) (p < 0.01). The GB ejection fraction had a poor correlation to the postoperative period (r = 0.232).

CONCLUSION

A gastrectomy appears to be a risk factor of GB dysmotility, which may play a major role in gallstone formation in gastrectomized patients.

Detection and differentiation of Listeria spp. by a single reaction based on multiplex PCR

The iap gene encodes the protein p60, which is common to all Listeria species. A previous comparison of the DNA sequences indicated conserved and species-specific gene portions. Based on these comparisons, a combination consisting of only five different primers that allows the specific detection and differentiation of Listeria species with a single multiplex PCR and subsequent gel analysis was selected. One primer was derived from the conserved 3' end and is specific for all Listeria species; the other four primers are specific for Listeria monocytogenes, L. innocua, L. grayi, or the three grouped species L. ivanovii, L. seeligeri, and L. welshimeri, respectively. The PCR method, which also enables the simultaneous detection of L. monocytogenes and L. innocua, was evaluated against conventional biotyping with 200 food hygiene-relevant Listeria strains. The results indicated the superiority of this technique. Thus, this novel type of multiplex PCR may be useful for rapid Listeria species confirmation and for identification of Listeria species for strains isolated from different sources.

Analysis of mesocarb analogues in urine and plasma of rats by high-performance liquid chromatography and thermospray liquid chromatography-mass spectrometry

The pharmacokinetics and metabolism of synthetic 2-hydroxymesocarb and 4-methyl-2-hydroxymesocarb analyzed by HPLC-DAD and thermospray LC-MS were studied in rats. Multistep liquid-liquid extraction (LLE) was used with diethyl ether at pH 7.0. The major metabolites of 2-hydroxymesocarb in both urine and plasma of the rat were the p-hydroxylated derivative of the phenylcarbamoyl group of the parent drug. The metabolites of 4-methyl-2-hydroxymesocarb in urine of rats may be the oxidized forms at the phenylcarbamoyl group of the parent drug. Absorption (ka) and elimination (ke) rate constants in plasma of 2-hydroxy-mesocarb were 0.0300 and 0.00485 min-1, respectively; those of 4-methyl-2-hydroxymesocarb were 0.0546 and 0.00797 min-1, respectively. The half-lives (t1/2) of 2-hydroxymesocarb and 4-methyl-2-hydroxymesocarb in plasma were 144 and 86 min, respectively.

Elephantiasis-like appearance of upper and lower extremities in Graves' dermopathy

Graves' dermopathy, affecting upper as well as lower extremities, is reported in a 50-year-old male patient addicted to multiple narcotic drugs. The narcotic drug administration routes include subcutaneous and intravenous injection in all limbs over a period of 29 years. The combination of drug injection trauma and Graves' dermopathy produced elephantiasis-like appearance of upper and lower limbs with impairment of their function; the left hand required amputation. Other features of Graves' disease, ie, hyperthyroidism and ophthalmopathy were severe and required multiple modes of therapy. Although the pathogenesis of Graves' dermopathy is unclear, it is surmised that trauma to skin might exacerbate it and preventive measures for trauma might be helpful in the management of dermopathy.