Protective role of kallistatin in oxygen-glucose deprivation and reoxygenation in human umbilical vein endothelial cells

OBJECTIVE

Ischemia-reperfusion (IR) injury is implicated in various clinical diseases. Kallistatin attenuates oxidative stress, and its deficiency has been associated with poor neurological outcomes after cardiac arrest. The present study investigated the antioxidant mechanism through which kallistatin prevents IR injury.

METHODS

Human umbilical vein endothelial cells (HUVECs) were transfected with small interfering RNA (siRNA) targeting the human kallistatin gene (SERPINA4). Following SERPINA4 knockdown, the level of kallistatin expression was measured. To induce IR injury, HUVECs were exposed to 24 h of oxygen-glucose deprivation and reoxygenation (OGD/R). To evaluate the effect of SERPINA4 knockdown on OGD/R, cell viability and the concentration of kallistatin, endothelial nitric oxide synthase (eNOS) and total NO were measured.

RESULTS

SERPINA4 siRNA transfection suppressed the expression of kallistatin in HUVECs. Exposure to OGD/R reduced cell viability, and this effect was more pronounced in SERPINA4 knockdown cells compared with controls. SERPINA4 knockdown significantly reduced kallistatin concentration regardless of OGD/R, with a more pronounced effect observed without OGD/R. Furthermore, SERPINA4 knockdown significantly decreased eNOS concentrations induced by OGD/R (P<0.01) but did not significantly affect the change in total NO concentration (P=0.728).

CONCLUSION

The knockdown of SERPINA4 resulted in increased vulnerability of HUVECs to OGD/R and significantly affected the change in eNOS level induced by OGD/R. These findings suggest that the protective effect of kallistatin against IR injury may contribute to its eNOS-promoting effect.

Taurodeoxycholate ameliorates DSS-induced colitis in mice

BACKGROUND

Inflammatory bowel disease (IBD) is typically managed using medications such as 5-aminosalicylic acid (5-ASA), glucocorticoids, anti-TNFα Ab, or anti-IL-12/23 Ab. However, some patients do not respond well to these treatments or frequently experience relapses. Therefore, alternative therapeutic options are needed. Since the activation of the inflammasome is crucial to the pathogenesis of IBD, inhibiting the inflammasome may be beneficial for patients.

MATERIALS AND METHODS

We tested the efficacy of taurodeoxycholate (TDCA), which is a known G-protein coupled receptor 19 (GPCR19) agonist, in a mouse colitis model induced by dextran sodium sulfate (DSS).

RESULTS

In the mouse colitis model, TDCA prevented loss of body weight, shortening of the colon, production of pro-inflammatory cytokines, infiltration of pro-inflammatory cells, and mucosal ulceration in the colon. In vitro, TDCA inhibited the activation of NF-κB in bone marrow-derived macrophages (BMDMs) by activating the cAMP-PKA axis. TDCA downregulated the expression of purinergic receptor P2X7 (P2X7R) and enhanced the colocalization of P2X7R with GPCR19, and inhibited the Ca2+ mobilization of BMDMs when stimulated with ATP or BzATP, which plays a pivotal role in activating the NLRP3 inflammasome (N3I) via P2X7R. TDCA inhibited the oligomerization of NLRP3-ASC and downregulated the expression of NLRP3 and ASC, as well as suppressed the maturation of pro-caspase-1 and pro-IL-1β. TDCA also increased the percentage of M2 macrophages while decreasing the number of M1 macrophages, Th1, Th2, and Th17 cells in the colon.

CONCLUSION

TDCA ameliorated DSS-induced colitis in mice, possibly by inhibiting both the priming phase (via the GPCR19-cAMP-PKA-NF-κB axis) and the activation phase (via the GPCR19-P2X7R-NLRP3-Caspase 1-IL-1β axis) of N3I signaling.

CD115- monocytic myeloid-derived suppressor cells are precursors of OLFM4high polymorphonuclear myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) consist of monocytic (M-) MDSCs and polymorphonuclear (PMN-) MDSCs that contribute to an immunosuppressive environment in tumor-bearing hosts. However, research on the phenotypic and functional heterogeneity of MDSCs in tumor-bearing hosts and across different disease stage is limited. Here we subdivide M-MDSCs based on CD115 expression and report that CD115^- M-MDSCs are functionally distinct from CD115⁺ M-MDSCs. CD115^- M-MDSCs increased in bone marrow and blood as tumors progressed. Transcriptome analysis revealed that CD115^- M-MDSCs expressed higher levels of neutrophil-related genes. Moreover, isolated CD115^- M-MDSCs had higher potential to be differentiated into PMN-MDSCs compared with CD115⁺ M-MDSCs. Of note, CD115^- M-MDSCs were able to differentiate into both olfactomedin 4 (OLFM4)^hi and OLFM4^lo PMN-MDSCs, whereas CD115⁺ M-MDSCs differentiated into a smaller proportion of OLFM4^lo PMN-MDSCs. In vivo, M-MDSC to PMN-MDSC differentiation occurred most frequently in bone marrow while M-MDSCs preferentially differentiated into tumor-associated macrophages in the tumor mass. Our study reveals the presence of previously unrecognized subtypes of CD115^- M-MDSCs in tumor-bearing hosts and demonstrates their cellular plasticity during tumorigenesis.

Taurodeoxycholate, a GPCR19 agonist, ameliorates atopic dermatitis in Balb/c mice

Keratinocytes are pivotal cells in the pathogenesis of atopic dermatitis (AD) as much as Th2 cells. In this sense, regulation of pro-inflammatory features of keratinocytes might be useful for AD patients. P2X7R-mediated activation of NLRP3 inflammasome (N3I) in keratinocytes and myeloid cells plays crucial roles in AD. Nonetheless, inhibition of P2X7R has not been feasible because of polymorphisms and ubiquitous expression of P2X7R. Here, we report that GPCR19 colocalizes with P2X7R and a GPCR19 agonist (taurodeoxycholate, TDCA) inhibits the activation of P2X7R. Noncistronically, TDCA inhibits NF-kB activation via the adenylate cyclase-PKA pathway and BzATP-mediated Ca⁺⁺ mobilization. Cistronically, TDCA suppresses the expression of P2X7R and N3I components in keratinocytes. NLRP3 oligomerization and the production of mature IL-1β and IL-18 was suppressed by TDCA treatment in keratinocytes. Topical TDCA treatment ameliorates proinflammatory features of AD in mice induced by DNCB, MC903 or oxazolone. Taken together, a GPCR19 agonist such as TDCA might inhibit P2X7R-mediated N3I activation of keratinocytes, which is crucial for the pathogenesis of AD. This article is protected by copyright. All rights reserved.

Non-classical anti-inflammatory drugs (NCAIDs) ameliorates brain inflammation and improves memory in Alzheimer’s diseases mice model

Alzheimer’s disease (AD) is the most common cause of dementia due to inflammatory neurodegeneration in the brain. Neuroinflammation caused by damage associated molecular pattern (DAMP: Aβ, ATP) leads to neuronal apoptosis. From our study HY209, a NCAIDs and a TGR5 agonist, inhibits neuroinflammation and neurodegeneration. In vitro, HY209 suppressed NLRP3-ASC oligomerization and production of mature IL-1β/IL-18 in microglia cells by Aβ ± ATP. HY209 inhibited Ca++ influx incurred by ATP or BzATP (P2X7 agonists). Ca++ influx of microglia from TGR5 KO was like that of P2X7 KO compared to wild type mice in response to BzATP. Suggesting that TGR5 is essential in P2X7-mediated Ca++ signaling and HY209 might play a role as an inverse agonist for TGR5 colocalized with P2X7. HY209 activates adenylate cyclase and cAMP. cAMP inhibits priming phase of inflammasomal activation, suppresses pro-inflammatory cytokine (TNF-α) production and oligomerization of NLRP3-ASC complex. Indicating that HY209 suppresses both priming and activation phase of NLRP3 inflammasome. In the 5x Familial Alzheimer’s disease (5xFAD) mice model, HY209 (1 mpk, i.p. or 30 mpk, p.o.) improves memory function, decreases Aβ plaque and neuronal apoptosis in the brain. Structure activity relationships were studied to screen out more potent HY209 derivatives (next generation NCAIDs) with increased bioavailability and higher BBB permeability. Considering efficacies of NSAIDs, PPARγ agonists, specific inhibitors (for TNF-α, ROS, RAGE, HMG-CoA, p38 MAPK, P2X7 and NLRP3) targeting limited number of proinflammatory pathways, NCAIDs could ameliorate broad spectrum of neuroinflammation that is crucial in preventing neurodegeneration and improving cognition and memory in AD.

GPCR19 Regulates P2X7R-Mediated NLRP3 Inflammasomal Activation of Microglia by Amyloid β in a Mouse Model of Alzheimer's Disease

Amyloid β (Aβ) and/or ATP activate the NLRP3 inflammasome (N3I) via P2X7R in microglia, which is crucial in neuroinflammation in Alzheimer’s disease (AD). Due to polymorphisms, subtypes, and ubiquitous expression of P2X7R, inhibition of P2X7R has not been effective for AD. We first report that taurodeoxycholate (TDCA), a GPCR19 ligand, inhibited the priming phase of N3I activation, suppressed P2X7R expression and P2X7R-mediated Ca⁺⁺ mobilization and N3I oligomerization, which is essential for production of IL-1β/IL-18 by microglia. Furthermore, TDCA enhanced phagocytosis of Aβ and decreased the number of Aβ plaques in the brains of 5x Familial Alzheimer’s disease (5xFAD) mice. TDCA also reduced microgliosis, prevented neuronal loss, and improved memory function in 5xFAD mice. The pleiotropic roles of GPCR19 in P2X7R-mediated N3I activation suggest that targeting GPCR19 might resolve neuroinflammation in AD patients.

Role of inflammasomes in neuroinflammation after ischemic stroke

Ischemic stroke is a devastating disease for which there is no effective medical treatment. In the era of extensive reperfusion strategies, established neuroprotectant candidates and novel therapeutic drugs with better targets are promising for treatment of acute ischemic stroke. Such targets include the inflammasome pathway, which contributes significantly to the pathogenesis of ischemic stroke. Following ischemic stroke, damage-associated molecular patterns from damaged cells activate inflammasomes, incur inflammatory responses, and induce cell death. Therefore, inhibiting inflammasome pathways has great promise for treatment of ischemic stroke. However, the efficacy and safety of inflammasome inhibitors remain controversial, and better upstream targets are needed for effective modulation. Herein, the roles of the inflammasome in ischemic injury caused by stroke are reviewed and the potential of neuroprotectants targeting the inflammasome is discussed.

Detection of Salmonella genes in stool samples of children aged 5 years and younger in urban and rural areas of Bangladesh

INTRODUCTION

Typhoid incidence in children is higher in urban areas than in rural areas of Bangladesh. This study examined whether healthy urban children harboured higher levels of Salmonella genes than healthy rural children.

METHODOLOGY

Stool samples from 140 children were studied: 70 from rural areas and 70 from urban metropolitan areas.

RESULTS

The stool samples of urban children contained more Salmonella genes (median 4, IQR 3-4) than those of rural children (median 3, IQR 3-4). This suggests that urban Bangladeshi children have more Salmonella genes in their guts than rural children. Especially, in those under 12 months of age, the Salmonella gene prevalence in urban children was unique. They had more Salmonella genes (median 4, IQR 4-5) than rural children in the same age group (median 3, IQR 2.5-4). We also found more Salmonella genes in urban children who drank tap water (median 4, IQR 3-5) than in rural children whose water source was tube well water (median 3, IQR 2-4) and boiled pond water (median 3, IQR 3-3.5). However, there was no significant difference of Salmonella genes between urban children who drank tap-water and children whose water source was a tube well (median 4, IQR 3-4).

CONCLUSIONS

These data suggest that the urban environment, including the drinking water supply system, increases the likelihood of healthy children in urban areas harbouring more potentially pathogenic Salmonella organisms in their gut than found in rural healthy children.

Peripheral natural killer cells and myeloid-derived suppressor cells correlate with anti-PD-1 responses in non-small cell lung cancer

Inhibition of immune checkpoint proteins like programmed death 1 (PD-1) is a promising therapeutic approach for several cancers, including non-small cell lung cancer (NSCLC). Although PD-1 ligand (PD-L1) expression is used to predict anti-PD-1 therapy responses in NSCLC, its accuracy is relatively less. Therefore, we sought to identify a more accurate predictive blood biomarker for evaluating anti-PD-1 response. We evaluated the frequencies of T cells, B cells, natural killer (NK) cells, polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), mononuclear myeloid-derived suppressor cells (M-MDSCs), and Lox-1+ PMN-MDSCs in peripheral blood samples of 62 NSCLC patients before and after nivolumab treatment. Correlation of immune-cell population frequencies with treatment response, progression-free survival, and overall survival was also determined. After the first treatment, the median NK cell percentage was significantly higher in responders than in non-responders, while the median Lox-1+ PMN-MDSC percentage showed the opposite trend. NK cell frequencies significantly increased in responders but not in non-responders. NK cell frequency inversely correlated with that of Lox-1+ PMN-MDSCs after the first treatment cycle. The NK cell-to-Lox-1+ PMN-MDSC ratio (NMR) was significantly higher in responders than in non-responders. Patients with NMRs ≥ 5.75 after the first cycle had significantly higher objective response rates and longer progression-free and overall survival than those with NMRs <5.75. NMR shows promise as an early predictor of response to further anti-PD-1 therapy.

Taurodeoxycholate, a master key locking both priming and activation signal necessary for inflammasomal activation of microglia by Amyloid beta in Alzheimer’s diseases

Alzheimer’s disease (AD) is an inflammatory neurodegenerative condition characterized by deposition of amyloid beta (Abeta) in the brain and origins dementia. Neuronal apoptosis following neuroinflammation by Abeta impairs cognition and memory. In this study we focused on Taurodeoxyxcholate (TDCA) is an active bile acid derivative with potent anti-inflammatory function.

In 5× Familial Alzheimer’s disease (5xFAD) mice model, chronic administration of TDCA in 5xFAD mice improved learning and memory in different memory test compared with PBS group. TDCA treatment significantly decreased neuronal apoptosis, load of Abeta plaques, the number of activated GFAP+ astrocytes and Iba-1+ microglia in different brain region of 5xFAD mice. CD11bhiGr1intF4/80+ myeloid cells in brain and spleen increased significantly in TDCA-treated group compared to PBS-treated group when brain single cell were immune-stained. In vitro, TDCA increased phagocytosis of Abeta. TDCA suppressed NLRP3-ASC oligomerization and production of mature IL-1β/IL-18 in Microglia by Abeta. TDCA inhibited Ca++ influx incurred by ATP or BzATP (P2X7 agonists). Compared with wild type, Ca++ influx of macrophages from TGR5 KO mice was like that of P2X7 KO mice in response to BzATP, suggesting that TDCA might play role as an inverse agonist for TGR5 complexed with P2X7. TDCA activates adenylate cyclase and cAMP inhibit priming phase of inflammasomal activation and oligomerization of NLRP3-ASC complex, suggesting that TDCA suppresses both priming and activation phase of NLRP3 inflammasome. TDCA and its novel chemical derivatives could be better choice in ameliorating broad spectrum of neuroinflammation to improve cognition and memory in AD patients.

HY209 ameliorates atopic dermatitis through NF-KB and P38 inhibition

HY209 has been reported to be a ligand for the membrane G protein–coupled receptor, TGR5. HY209 could inhibit inflammatory responses in sepsis by increasing number of immunosuppressive myeloid-derived suppressor cells (MDSC), suggesting the potent role of HY209 in the treatment of atopic dermatitis (AD). Here HY209 was evaluated whether it controls inflammatory immune responses in AD. We employed mouse AD model using a topical treatment of dinitrochlorobenzene (DNCB) on the dorsal skin of Balb/c mice. HY209-treated mice showed significantly reduction in Th2 immune responses, shown as lower IgE serum, and inhibition of T cells mast cells, eosinophilia and neutrophil recruitment accompanied with reduced in epidermal and dermal thickness in skin of HY209 treated mice. Interestingly, regulatory T cells noticeably increased upon to HY209 treatment along with inhibition of type 2 cytokines production. Proteogenomic analyses of mouse skin demonstrated upregulated expression of molecules responsible for tissue regeneration and downregulated expression of proinflammatory molecules. Consistent with these findings, in vitro data indicated that HY209 decreased production of thymic stromal lymphopoietin (TSLP) and CCL17 (TARC) through inhibition of NF-KB and MAPK (P38) pathway. Taken together, HY209 ameliorates AD in mice by normalizing Th1/Th2 imbalance immune responses and inhibiting various pro-inflammatory responses via TGR5-cAMP-PKA axis, Suggesting HY209 could be a promising therapeutic candidate for AD.

HY209 alleviates inflammation in colitis mice through NLRP3 inflammasome inhibition

The anti-inflammatory effects of HY209 have been identified in sepsis. However, the anti-inflammatory potential of HY209 in colitis has not yet been investigated. In here, we evaluated the therapy efficacy of HY209 in an acute colitis mice model which induced by using dextran sulfate sodium (DSS). Compare to vehicle mice, HY209 treated mice showed significantly less body weight loss, lower disease activity index, longer colon length, as well as a lower histology disease scores. Meanwhile, the expression of pro-inflammatory cytokines (TNF-α, IL-1ß, IL-6) were reduced in colon tissue after HY209 treatment. Furthermore, HY209 treated mice significantly reduced inflammatory macrophage, but increased anti-inflammatory macrophage in lamina propria. In vitro, HY209 showed a strong inhibition to LPS and ATP/BzATP activated NLRP3 inflammasome formation in the bone marrow derived macrophages (BMDMs). In summary, our findings demonstrated that HY209 alleviates inflammation in colitis mice through NLRP3 inflammasome inhibition, discovery the potential of HY209 as a therapeutic option for colitis.

Expansion of Myeloid-Derived Suppressor Cells Correlates with Renal Progression in Type 2 Diabetic Nephropathy

Type 2 diabetic nephropathy (T2DN) progresses with an increasingly inflammatory milieu, wherein various immune cells are relevant. Herein, we investigated the levels of myeloid-derived suppressor cells (MDSCs) and their clinical implication in patients with T2DN. A total of 91 subjects (T2DN, n=80; healthy, n=11) were recruited and their PBMCs were used for flow cytometric analysis of polymorphonuclear (PMN-) and monocytic (M-) MDSCs, in addition to other immune cell subsets. The risk of renal progression was evaluated according to the quartiles of MDSC levels using the Cox model. The proportion of MDSCs in T2DN patients was higher than in healthy individuals (median, 6.7% vs. 2.5%). PMN-MDSCs accounted for 96% of MDSCs, and 78% of PMN-MDSCs expressed Lox-1. The expansion of PMN-MDSCs was not related to the stage of T2DN or other kidney disease parameters such as glomerular filtration rate and proteinuria. The production of ROS in PMN-MDSCs of patients was higher than in neutrophils of patients or in immune cells of healthy individuals, and this production was augmented under hyperglycemic conditions. The 4th quartile group of PMN-MDSCs had a higher risk of renal progression than the 1st quartile group, irrespective of adjusting for multiple clinical and laboratory variables. In conclusion, PMN-MDSCs are expanded in patients with T2DN, and may represent as an immunological biomarker of renal progression.

Proteomic Analysis of Amniotic Fluid Proteins for Predicting the Outcome of Emergency Cerclage in Women with Cervical Insufficiency

We aimed to identify novel biomarkers in amniotic fluid (AF) that predict the outcome of emergency cerclage in women with cervical insufficiency. This retrospective cohort study included 40 singleton pregnant women who received emergency cerclage for cervical insufficiency (17-25 weeks) and underwent amniocentesis. Label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify AF proteins in pooled samples (n = 16) using a nested case-control approach. The six candidate biomarkers of interest were validated by enzyme-linked immunosorbent assays (ELISA) in the final cohort (n = 40). The differentially expressed proteins (DEPs) were analyzed by pathway analysis software. The primary outcome measure was failure of emergency cerclage [defined as spontaneous preterm delivery (SPTD) at < 34 weeks of gestation after cerclage placement]. Sixty-eight proteins were differentially expressed (P < 0.001) in AF from SPTD cases and near-term controls, of which 44 (64.7%) were upregulated and 24 (35.3%) were downregulated. Validation by ELISA confirmed that AF from women with cerclage failure contained significantly higher levels of myeloperoxidase, lactoferrin, glucose-6-phosphate isomerase, lipocalin-2, and lymphocyte cytosolic protein 1, the first four of which were independent of cervical dilatation at presentation. The five pathways with the most differentially regulated proteins were actin cytoskeleton signaling, acute phase response signaling, ILK signaling, glycolysis, and gluconeogenesis. Proteomic analyses of AF in this study identified DEPs and specific protein pathways related to poor prognosis after emergency cerclage for cervical insufficiency. Four novel independent biomarkers in AF for cerclage failure have been identified using proteomics.

Differential interleukin-1β induction by uropathogenic Escherichia coli correlates with its phylotype and serum C-reactive protein levels in Korean infants

Urinary tract infection (UTI) is one of the most common bacterial infections in infants less than age 1 year. UTIs frequently recur and result in long-term effects include sepsis and renal scarring. Uropathogenic Escherichia coli (UPEC), the most prevalent organism found in UTIs, can cause host inflammation via various virulence factors including hemolysin and cytotoxic necrotizing factors by inducing inflammatory cytokines such as interleukin (IL)-1β. However, the ability of each UPEC organism to induce IL-1β production may differ by strain. Furthermore, the correlation between differential IL-1β induction and its relevance in pathology has not been well studied. In this study, we isolated UPEC from children under age 24 months and infected bone-marrow derived macrophages with the isolates to investigate secretion of IL-1β. We found that children with higher concentrations of C-reactive protein (CRP) were more likely to harbor phylotype B2 UPEC strains that induced more IL-1β production than phylotype D. We also observed a significant correlation between serum CRP level and in vitro IL-1β induction by phylotype B2 UPEC bacteria. Our results highlight the diversity of UPEC in terms of IL-1β induction capacity in macrophages and suggest a potential pathogenic role in UTIs by inducing inflammation in infants.

Evaluation of acute and subacute toxicity of sodium taurodeoxycholate in rats

Taurodeoxycholate (TDCA) inhibits various inflammatory responses suggesting potential clinical application. However, the toxicity of TDCA has not been evaluated in detail in vivo. We investigated the acute toxicity and 4-week repeated-dose toxicity of TDCA following intravenous infusion under Good Laboratory Practice regulations. In the sighting study of acute toxicity, one of two rats (one male and one female) treated with 300 mg/kg TDCA died with hepatotoxicity, suggesting that the approximate 50% lethal dose of TDCA is 300 mg/kg. Edema and discoloration were observed at the injection sites of tails when rats were infused with 150 mg/kg or higher amount of TDCA once. In 4-week repeated-dose toxicity study, no treatment-related mortality or systemic changes in hematology and serum biochemistry, organ weights, gross pathology, or histopathology were observed. However, the tail injection site showed redness, discharge, hardening, and crust formation along with histopathological changes such as ulceration, edema, fibrosis, and thrombosis when rats were infused with 20 mg/kg TDCA. Taken together, TDCA induced no systemic toxicity or macroscopic lesions at the injection site at a dose of 10 mg/kg/day, which is 33 times higher than the median effective dose observed in a mouse sepsis model. These findings suggest that TDCA might have a favorable therapeutic index in clinical applications.

Nonclinical toxicology studies with sodium taurodeoxycholate: acute and subacute toxicity in dogs

Sodium taurodeoxycholate (TDCA) has been investigated for various inflammatory disorders such as sepsis. We recently evaluated nonclinical safety profile of TDCA using rats infused intravenously. As a series of preclinical safety investigations, we further conducted toxicity studies with TDCA delivered to dogs via intravenous administration under Good Laboratory Practice regulation in this study. In dose range-finding study (dose escalation study), dogs given with TDCA at a dose of 150 mg/kg showed marked changes in clinical signs, hematology, and serum biochemistry. And biochemical markers of liver damage and local skin lesions were observed following intravenous infusion of 100 mg/kg TDCA, suggesting that 100 mg/kg was chosen as the highest dose of TDCA for 4-week repeated-dose toxicity study using dogs. Despite no treatment-related significant changes in body weight, food consumption, ophthalmoscopy, and urinalysis, skin lesions were observed at the injection site of animals administered with higher than 50 mg/kg of TDCA along with biochemical and histopathological changes associated with liver injury. However, most of off-target effects were found to be reversible since these were recovered after stopping TDCA infusion. These findings indicate that the no-observed-adverse-effect-level (NOAEL) for TDCA in dogs was considered to be 5 mg/kg/d. Taken together, our results provide important toxicological profiles regarding the safe dose of TDCA for drug development or clinical application.

Taurodeoxycholate Increases the Number of Myeloid-Derived Suppressor Cells That Ameliorate Sepsis in Mice

Bile acids (BAs) control metabolism and inflammation by interacting with several receptors. Here, we report that intravenous infusion of taurodeoxycholate (TDCA) decreases serum pro-inflammatory cytokines, normalizes hypotension, protects against renal injury, and prolongs mouse survival during sepsis. TDCA increases the number of granulocytic myeloid-derived suppressor cells (MDSCLT) distinctive from MDSCs obtained without TDCA treatment (MDSCL) in the spleen of septic mice. FACS-sorted MDSCLT cells suppress T-cell proliferation and confer protection against sepsis when adoptively transferred better than MDSCL. Proteogenomic analysis indicated that TDCA controls chromatin silencing, alternative splicing, and translation of the immune proteome of MDSCLT, which increases the expression of anti-inflammatory molecules such as oncostatin, lactoferrin and CD244. TDCA also decreases the expression of pro-inflammatory molecules such as neutrophil elastase. These findings suggest that TDCA globally edits the proteome to increase the number of MDSCLT cells and affect their immune-regulatory functions to resolve systemic inflammation during sepsis.

Cardiolipin activates antigen-presenting cells via TLR2-PI3K-PKN1-AKT/p38-NF-kB signaling to prime antigen-specific naïve T cells in mice

Mitochondrial defects and antimitochondrial cardiolipin (CL) antibodies are frequently detected in autoimmune disease patients. CL from dysregulated mitochondria activates various pattern recognition receptors, such as NLRP3. However, the mechanism by which mitochondrial CL activates APCs as a damage-associated molecular pattern to prime antigen-specific naïve T cells, which is crucial for T-cell-dependent anticardiolipin IgG antibody production in autoimmune diseases is unelucidated. Here, we show that CL increases the expression of costimulatory molecules in CD11c⁺ APCs both in vitro and in vivo. CL activates CD11c⁺ APCs via TLR2-PI3K-PKN1-AKT/p38MAPK-NF-κB signaling. CD11c⁺ APCs that have been activated by CL are sufficient to prime H-Y peptide-specific naïve CD4⁺ T cells and OVA-specific naïve CD8⁺ T cells. TLR2 is necessary for anti-CL IgG antibody responses in vivo. Intraperitoneal injection of CL does not activate CD11c⁺ APCs in CD14 KO mice to the same extent as in wild-type mice. CL binds to CD14 (Kd = 7 × 10^-7 M). CD14, but not MD2, plays a role in NF-kB activation by CL, suggesting that CD14⁺ macrophages contribute to recognizing CL. In summary, CL activates signaling pathways in CD11c⁺ APCs through a mechanism similar to gram (+) bacteria and plays a crucial role in priming antigen-specific naïve T cells.

Pattern of Respiratory Deterioration in Sporadic Amyotrophic Lateral Sclerosis According to Onset Lesion by Using Respiratory Function Tests

Most amyotrophic lateral sclerosis (ALS) patients show focal onset of upper and lower motor neuron signs and spread of symptoms to other regions or the other side clinically. Progression patterns of sporadic ALS are unclear. The aim of this study was to evaluate the pattern of respiratory deterioration in sporadic ALS according to the onset site by using respiratory function tests. Study participants included 63 (42 cervical-onset [C-ALS] and 21 lumbosacral-onset [L-ALS]) ALS patients and 31 healthy controls. We compared respiratory function test parameters among the 3 groups. Age was 57.4±9.6 (mean±SD), 60.8±9, and 60.5±7 years, and there were 28, 15, and 20 male participants, in the C-ALS, L-ALS, and control groups, respectively. Disease duration did not differ between C-ALS and L-ALS patients. Sniff nasal inspiratory pressure (SNIP) was significantly low in C-ALS patients compared with controls. Maximal expiratory pressure (MEP) and forced vital capacity percent predicted (FVC% predicted) were significantly low in C-ALS and L-ALS patients compared with controls. Maximal inspiratory pressure to maximal expiratory pressure (MIP:MEP) ratio did not differ among the 3 groups. Eighteen C-ALS and 5 L-ALS patients were followed up. ΔMIP, ΔMEP, ΔSNIP, ΔPEF, and ΔFVC% predicted were higher in C-ALS than L-ALS patients without statistical significance. Fourteen C-ALS (77.8%) and 3 L-ALS (60%) patients showed a constant MIP:MEP ratio above or below 1 from the first to the last evaluation. Our results suggest that vulnerability of motor neurons in sporadic ALS might follow a topographic gradient.

Modulation of SOD1 Subcellular Localization by Transfection with Wild- or Mutant-type SOD1 in Primary Neuron and Astrocyte Cultures from ALS Mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurological disorder characterized by selective degeneration of motor neurons. Mutant superoxide dismutase 1 (SOD1) is often found as aggregates in the cytoplasm in motor neurons of various mouse models and familial ALS patients. The interplay between motor neurons and astrocytes is crucial for disease outcome, but the mechanisms underlying this phenomenon remain unknown. In this study, we investigated whether transient transfection with wild-type and mutant-type SOD1 may lead to amplification of mutant SOD1-mediated toxicity in cortical neurons and astrocytes derived from wild-type and mutant-type (human G93A-SOD1) mice. In transgenic mice expressing either wild- or mutant-type SOD1, we found that green fluorescent protein (GFP)-wtSOD1 was present in the cytoplasm and nuclei of wild-type cortical neurons and astrocytes, whereas GFP-mutant SOD1 was mainly cytoplasmic in wild- and mutant-type cortical neurons and astrocytes. These findings indicate that intracellular propagation of misfolding of GFP-wt or mtSOD1 are possible mediators of toxic processes involved in initiating mislocalization and aggregation. Here, we provide evidence that cytoplasmic aggregates induce apoptosis in G93A-SOD1 mouse cortical neurons and astrocytes and that the toxicity of mutant SOD1 in astrocytes is similar to the pathological effects of ALS on neurons in vitro. Collectively, our results indicate that mtSOD1 probably interacts with wtSOD1 via an unknown mechanism to produce augmented toxicity and may influence aggregate formation and apoptosis.

Functional manipulation of dendritic cells by photoswitchable generation of intracellular reactive oxygen species

Reactive oxygen species (ROS) play an important role in cellular signaling as second messengers. However, studying the role of ROS in physiological redox signaling has been hampered by technical difficulties in controlling their generation within cells. Here, we utilize two inert components, a photosensitizer and light, to finely manipulate the generation of intracellular ROS and examine their specific role in activating dendritic cells (DCs). Photoswitchable generation of intracellular ROS rapidly induced cytosolic mobilization of Ca(2+), differential activation of mitogen-activated protein kinases, and nuclear translocation of NF-κB. Moreover, a transient intracellular ROS surge could activate immature DCs to mature and potently enhance migration in vitro and in vivo. Finally, we observed that intracellular ROS-stimulated DCs enhanced antigen specific T-cell responses in vitro and in vivo, which led to delayed tumor growth and prolonged survival of tumor-bearing mice when immunized with a specific tumor antigen. Therefore, a transient intracellular ROS surge alone, if properly manipulated, can cause immature DCs to differentiate into a motile state and mature forms that are sufficient to initiate adaptive T cell responses in vivo.

GM-CSF-loaded chitosan hydrogel as an immunoadjuvant enhances antigen-specific immune responses with reduced toxicity

Background

The application of vaccine adjuvants has been vigorously studied for a diverse range of diseases in order to improve immune responses and reduce toxicity. However, most adjuvants have limited uses in clinical practice due to their toxicity.

Methods

Therefore, to reduce health risks associated with the use of such adjuvants, we developed an advanced non-toxic adjuvant utilizing biodegradable chitosan hydrogel (CH-HG) containing ovalbumin (OVA) and granulocyte-macrophage colony-stimulating factor (GM-CSF) as a local antigen delivery system.

Results

After subcutaneous injection into mice, OVA/GM-CSF-loaded CH-HG demonstrated improved safety and enhanced OVA-specific antibody production compared to oil-based adjuvants such as Complete Freund’s adjuvant (CFA) or Incomplete Freund’s adjuvant (IFA). Moreover, CH-HG system-mediated immune responses was characterized by increased number of OVA-specific CD4⁺ and CD8⁺ INF-γ⁺ T cells, leading to enhanced humoral and cellular immunity.

Conclusions

In this study, the improved safety and enhanced immune response characteristics of our novel adjuvant system suggest the possibility of the extended use of adjuvants in clinical practice with reduced apprehension about toxic side effects.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-014-0048-x) contains supplementary material, which is available to authorized users.

Transcriptional regulation of IFN-λ genes in hepatitis C virus-infected hepatocytes via IRF-3·IRF-7·NF-κB complex

Hepatitis C virus (HCV) infection in hepatocytes stimulates innate antiviral responses including the production of type III interferons (IFN-λ), including IL-28A, IL-28B, and IL-29. However, the molecular mechanism(s) regulating the expression of IFN-λ genes in HCV-infected hepatocytes remains undefined. In this study, we examined regulatory elements involved in the induction of IFN-λ genes following HCV infection in hepatocytes and further determined the binding of specific transcription factor(s) to promoter regions of IFN-λ genes. Our studies reveal that the regulatory portion for IL-28A, IL-28B, and IL-29 genes is localized to a 1-kb region in their respective promoters. Notably, interferon regulatory factor (IRF)-3 and -7 are the key transcriptional factors for the induction of IL-28A and IL-28B genes, whereas NF-κB is an additional requirement for the induction of the IL-29 gene. Ligation of Toll-like receptors (TLR) 3, 7, 8, and 9, which also activate IRFs and NF-κB, resulted in more robust production of IFN-λ than that observed with HCV infection, verifying the importance of TLR pathways in IFN-λ production. Furthermore, the addition of IFN-λ to HCV-infected hepatocytes decreased viral replication and produced a concurrent reduction in microRNA-122 (miR-122). The decrease in viral replication was enhanced by the co-administration of IFN-λ and miR-122 inhibitor (miRIDIAN), suggesting that such combinatorial therapies may be beneficial for the treatment of chronic HCV infection.

The effects of climate change and globalization on mosquito vectors: evidence from Jeju Island, South Korea on the potential for Asian tiger mosquito (Aedes albopictus) influxes and survival from Vietnam rather than Japan

Background

Climate change affects the survival and transmission of arthropod vectors as well as the development rates of vector-borne pathogens. Increased international travel is also an important factor in the spread of vector-borne diseases (VBDs) such as dengue, West Nile, yellow fever, chikungunya, and malaria. Dengue is the most important vector-borne viral disease. An estimated 2.5 billion people are at risk of infection in the world and there are approximately 50 million dengue infections and an estimated 500,000 individuals are hospitalized with dengue haemorrhagic fever annually. The Asian tiger mosquito (Aedes albopictus) is one of the vectors of dengue virus, and populations already exist on Jeju Island, South Korea. Currently, colder winter temperatures kill off Asian tiger mosquito populations and there is no evidence of the mosquitos being vectors for the dengue virus in this location. However, dengue virus-bearing mosquito vectors can inflow to Jeju Island from endemic area such as Vietnam by increased international travel, and this mosquito vector's survival during colder winter months will likely occur due to the effects of climate change.

Methods and Results

In this section, we show the geographical distribution of medically important mosquito vectors such as Ae. albopictus, a vector of both dengue and chikungunya viruses; Culex pipiens, a vector of West Nile virus; and Anopheles sinensis, a vector of Plasmodium vivax, within Jeju Island, South Korea. We found a significant association between the mean temperature, amount of precipitation, and density of mosquitoes. The phylogenetic analyses show that an Ae. albopictus, collected in southern area of Jeju Island, was identical to specimens found in Ho Chi Minh, Vietnam, and not Nagasaki, Japan.

Conclusion

Our results suggest that mosquito vectors or virus-bearing vectors can transmit from epidemic regions of Southeast Asia to Jeju Island and can survive during colder winter months. Therefore, Jeju Island is no longer safe from vector borne diseases (VBDs) due to the effects of globalization and climate change, and we should immediately monitor regional climate change to identify newly emerging VBDs.

Nanog signaling in cancer promotes stem-like phenotype and immune evasion

Adaptation of tumor cells to the host is a major cause of cancer progression, failure of therapy, and ultimately death. Immune selection drives this adaptation in human cancer by enriching tumor cells with a cancer stem cell-like (CSC-like) phenotype that makes them resistant to CTL-mediated apoptosis; however, the mechanisms that mediate CSC maintenance and proliferation are largely unknown. Here, we report that CTL-mediated immune selection drives the evolution of tumor cells toward a CSC-like phenotype and that the CSC-like phenotype arises through the Akt signaling pathway via transcriptional induction of Tcl1a by Nanog. Furthermore, we found that hyperactivation of the Nanog/Tcl1a/Akt signaling axis was conserved across multiple types of human cancer. Inhibition of Nanog in a murine model of colon cancer rendered tumor cells susceptible to immune-mediated clearance and led to successful, long-term control of the disease. Our findings establish a firm link among immune selection, disease progression, and the development of a stem-like tumor phenotype in human cancer and implicate the Nanog/Tcl1a/Akt pathway as a central molecular target in this process.

Action of lipopolysaccharide on interstitial cells of cajal from mouse small intestine

BACKGROUND AND PURPOSE

Lipopolysaccharide (LPS) induces intestinal dysmotility by alteration of smooth muscle and enteric neuronal activities. However, there is no report on the modulatory effects of LPS on the interstitial cells of Cajal (ICCs). We investigated the effect of LPS and its signal transduction in ICCs.

METHODS

We performed whole-cell patch clamp and RT-PCR in cultured ICCs from mouse small intestine.

RESULTS

LPS suppressed the generation of pacemaker currents of ICCs. The mRNA transcripts for Toll-like receptor 4 (TLR4) were expressed in ICCs. However, the inhibitory action of LPS on pacemaker currents from TLR4(+/+) mice was not present in TLR4(-/-) mice. The inhibitory effects of LPS on ICCs were blocked by glibenclamide (an inhibitor of ATP-sensitive K(+) channels), NS-398 (a COX-2 inhibitor), AH6808 [a prostaglandin E(2) (PGE(2))-EP(2) receptor antagonist], ODQ (an inhibitor of guanylate cyclase) and L-NAME [an inhibitor of nitric oxide synthase (NOS)]. Furthermore, genistein and herbimycin A (tyrosine kinase inhibitors) blocked the LPS-induced inhibitory action on pacemaker activity in ICCs.

CONCLUSIONS

LPS can activate ICCs to release NO and PGE(2) through TLR4 activation. The released NO and PGE(2) inhibit pacemaker currents by activating ATP-sensitive K(+) channels. The LPS actions are mediated by tyrosine kinase signaling pathways.

A multifunctional core-shell nanoparticle for dendritic cell-based cancer immunotherapy

Dendritic cell-based cancer immunotherapy requires tumour antigens to be delivered efficiently into dendritic cells and their migration to be monitored in vivo. Nanoparticles have been explored as carriers for antigen delivery, but applications have been limited by the toxicity of the solvents used to make nanoparticles, and by the need to use transfection agents to deliver nanoparticles into cells. Here we show that an iron oxide-zinc oxide core-shell nanoparticle can deliver carcinoembryonic antigen into dendritic cells while simultaneously acting as an imaging agent. The nanoparticle-antigen complex is efficiently taken up by dendritic cells within one hour and can be detected in vitro by confocal microscopy and in vivo by magnetic resonance imaging. Mice immunized with dendritic cells containing the nanoparticle-antigen complex showed enhanced tumour antigen specific T-cell responses, delayed tumour growth and better survival than controls.

Enhancement of DNA vaccine potency by antigen linkage to IFN-γ-inducible protein-10

DNA vaccines have emerged as an attractive approach to generate antigen-specific T-cell immune response. Nevertheless, the potency of DNA vaccines still needs to be improved for cancer immunotherapy. In this study, we explored whether functional linkage of a Th1-polarizing chemokine, IP-10, to a model tumor antigen, human papillomavirus type 16 (HPV-16) E7, enhanced DNA vaccine potency. IP-10 linkage changed the location of E7 from the nucleus to the endoplasmic reticulum and led to the secretion of functionally chemoattractive chimeric IP-10/E7 protein. In addition, this linkage drastically enhanced the endogenous processing of E7 antigen through MHC class I. More importantly, we found that C57BL/6 mice intradermally vaccinated with IP-10/E7 DNA exhibited a dramatic increase in the number of E7-specific CD4(+) Th1 T-cells and CD8(+) T-cells and, consequently, were strongly resistant over the long term to E7-expressing tumors compared to mice vaccinated with wild-type E7 DNA. Thus, because of the increase in tumor antigen-specific T-cell immune responses obtained through both enhanced antigen presentation and chemoattraction, vaccination with DNA encoding IP-10 linked to a tumor antigen holds great promise for treating tumors.

Global gene expression profile of Orientia tsutsugamushi

Orientia tsutsugamushi, an obligate intracellular bacterium, is the causative agent of Scrub typhus. The control mechanisms for bacterial gene expression are largely unknown. Here, the global gene expression of O. tsutsugamushi within eukaryotic cells was examined using a microarray and proteomic approaches for the first time. These approaches identified 643 genes, corresponding to approximately 30% of the genes encoded in the genome. The majority of expressed genes belonged to several functional categories including protein translation, protein processing/secretion, and replication/repair. We also searched the conserved sequence blocks (CSBs) in the O. tsutsugamushi genome which is unique in that up to 40% of its genome consists of dispersed repeated sequences. Although extensive shuffling of genomic sequences was observed between two different strains, 204 CSBs, covering 48% of the genome, were identified. When combining the data of CSBs and global gene expression, the CSBs correlates well with the location of expressed genes, suggesting the functional conservation between gene expression and genomic location. Finally, we compared the gene expression of the bacteria-infected fibroblasts and macrophages using microarray analysis. Some major changes were the downregulation of genes involved in translation, protein processing and secretion, which correlated with the reduction in bacterial translation rates and growth within macrophages.

Modification of dendritic cells with interferon-gamma-inducible protein-10 gene to enhance vaccine potency

BACKGROUND

Dendritic cell (DC)-based vaccines have become a promising modality in cancer immunotherapy. However, their ability to initiate tumor antigen-specific T cell immunity is limited in various negative-feedback mechanisms. The rapid down-regulation of chemokines, such as the interferon inducible protein of 10 kDa (IP-10), which chemoattracts activated antigen-specific CD8+ T cells, would represent negative-feedback regulation. Therefore, we attempted to improve DC vaccine potency by introducing the IP-10 gene retrovirally aiming to replenish the chemoattractive activity of DCs.

METHODS

We introduced IP-10 gene into DC2.4 cells, referred to as DC-IP10, using a retroviral system. Nonsecretable mIP-10-expressing DCs (DC-mIP10) were also prepared to evaluate the effects of secretion in IP-10-mediated modulation of DC biology. Additionally, in vitro and in vivo activation of antigen-specific T lymphocytes and in vivo anti-tumor effects induced by DC-IP10 or DC-mIP10 were determined.

RESULTS

The modification of DC2.4 cells with the IP-10 gene resulted in the secretion of functionally chemoattractive IP-10 and, unexpectedly, a significant up-regulation of surface expression in co-stimulatory molecules, such as CD40 and CD80, compared to that of DCs with vector control (DC-no insert). DC-mIP10 also displayed the partially matured phenotypes but failed to recruit antigen-specific T cells in an in vitro cell culture system. Consistently, DC-IP10 generated more tumor antigen-specific CD8+ T cells and stronger anti-tumor effects in vaccinated mice than did control DCs and DC-mIP10.

CONCLUSIONS

The results obtained provide the groundwork for a future clinical translation of the chemokine-based genetic modification of DCs to increase their vaccine potency.

CD14 but not MD2 transmit signals from DAMP

Both pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) activate antigen-presenting cells, often through the same pattern recognition receptors (PRR), such as Toll-like receptors (TLR). The TLR4-CD14-MD2 and TLR2-CD14 complexes have been shown to play a role in the recognition of lipopolysaccharide (LPS) and peptidoglycan (PG), respectively. Since many DAMPs have also been known to activate TLR2 or TLR4 pathways, we dissected the role of each molecule in the receptor complexes (TLR2-D14-MD2) responding to DAMP (necrotic cells) or PAMP (LPS and PG). CD14 played a significant role in the activation of NF-kappaB in response to necrotic cells in the presence or absence of TLR2. However, MD2 did not play a significant role in NF-kappaB activation by necrotic cells. Intriguingly, MD2 did play a significant role in activating NF-kappaB by PG in the presence of TLR2-CD14. Compared with CD14(pos) B6 mice, CD14(neg) B6 mice showed delayed production of IL12p40 in response to necrotic cells in vivo. Microarray analysis showed that various pro-inflammatory genes of peritoneal cells were regulated in response to necrotic cells, in a CD14-dependent manner. The CD14 appears to recognize necrotic cells in addition to LPS, PG, apoptotic cells, and lipids, suggesting that CD14 might be a universal adaptor for DAMP and PAMP. On the contrary, MD2 recognizes only exogenous PAMP, when complexed with TLR2-CD14 or TLR4-CD14. Taken together, MD2 appears to discriminate between DAMP and PAMP.

Detection and hazard assessment of pathogenic microorganisms in medical wastes

This study was undertaken to investigate the types and concentrations of microbial agents in various medical wastes as well as to characterize their survivals in these wastes at different temperatures for microbial risk assessment. Medical wastes collected from 5 major hospitals in South Korea were classified and stored at three different temperatures (-20, 6, and 30 degrees C). Presence of various microorganisms such as pathogenic viruses and bacteria were investigated by both cultivation and by (RT)-PCR assays. A number of (opportunistic) pathogenic bacteria, including Pseudomonas spp., Lactobacillus spp., Staphylococcus spp., Micrococcus spp., Kocuria spp., Brevibacillus spp., Microbacterium oxydans, and Propionibacterium acnes, were identified from the various medical wastes. In addition, pathogenic viruses such as noroviruses and hepatitis B virus were also detected in one of the human tissue wastes. Commonly identified bacterial and viral pathogens such as Pseudomonas spp., Corynebacterium diphtheriae, Escherichia coli, Staphylococcus spp., and respiratory synctial virus (RSV) were inoculated into either gauzes or diapers, and their survivals were characterized. Viral agents such as RSV showed poor survival in most environmental conditions, and demonstrated that various pathogens could be present in medical wastes but that the associated health risk appeared to be low. However, medical waste should be carefully controlled and monitored to prevent nosocomial infection associated with the exposure to these wastes.

Partial role of TLR4 as a receptor responding to damage-associated molecular pattern

Part of pathogen-associated molecular pattern (PAMP) and damage-associated molecular pattern (DAMP) activate antigen-presenting cells through Toll-like receptors (TLRs) to initiate immune responses. However, controversy remains if TLR4 mediates DAMP signaling due to the confounding effects of potential LPS contamination. To test if TLR4 functions as a true receptor for DAMP, we compared TLR4(pos)- and TLR4(neg)-responders in vitro and in vivo after stimulation with whole necrotic cell (NC) lysates. Using CHO reporter cells transfected with anti-TLR4-siRNAs, TLR4 was found to partially mediate NF-kappaB activation in response to NC lysates. TLR4(neg) DCs exhibited less I-A(b) expression and nitric oxide secretion than TLR4(pos) DCs upon NC stimulation and this defect was well correlated with diminished presentation of H-Y antigen by TLR4(neg) DCs to I-A(b)-restricted CD4(pos) Marilyn T cells in vitro. Similarly, TLR4(neg) DCs showed significantly less expression of I-A(b), CD80, CD86, and CD40 than TLR4(pos) DCs when NC lysates were injected into peritoneal cavity. Finally, delayed type hypersensitivity response to OVA was significantly decreased in TLR4(neg) mice when NCs were used as an adjuvant. Taken together, our data support the idea that part of the endogenous ligands presented by NCs could activate APCs thru TLR4 and contribute to the development of antigen-specific adaptive immunity. Therefore, endogenous DAMP ligands themselves, not contaminated LPS, activate TLR4 signaling leading to activation of professional antigen-presenting cells.

TLR4-independent and PKR-dependent interleukin 1 receptor antagonist expression upon LPS stimulation

Dendritic cells (DCs) induce innate immune responses by recognizing bacterial LPS through TLR4 receptor complexes. In this study, we compared gene expression profiles of TLR4 knockout (TLR4(neg)) DCs and wild type (TLR4(pos)) DCs after stimulating with LPS. We found that the expression of various inflammatory genes by LPS were TLR4-independent. Among them, interleukin 1 receptor antagonist (IL-1rn) was of particular interest since IL-1rn is a potent natural inhibitor of proinflammatory IL-1. Using RT-PCR, real-time PCR, immunoblotting and ELISA, we demonstrated that IL-1rn was induced by DCs stimulated with LPS in the absence of TLR4. 2-Aminopurine, a pharmacological PKR inhibitor, completely abrogated LPS-induced expression of IL-1rn in TLR4(neg) DCs, suggesting that LPS-induced TLR4-independent expression of IL-1rn might be mediated by PKR pathways. Considering that IL-1rn is a physiological inhibitor of IL-1, TLR4-independent and PKR-dependent pathways might be crucial in counter-balancing proinflammatory effector functions of DCs resulted from TLR4-dependent activation by LPS.

Improved survival in experimental sepsis with conjugated cholic acids preventing activation of dendritic cells by LPS (134.48)

The incidence and mortality of sepsis have steadily increased during the last few decades. The development of targeted therapy has been hampered due to multiple targets of LPS. Here, we tested bioemulsifiers inhibiting interaction of LPS with dendritic cells (DCs) in vitro and in an experimental mouse model. We found that glycine-conjugated cholic acids (CCA) and taurine-CCA reduced LPS-mediated NF-κB activation by inhibiting LPS binding with target cells. CCAs were also able to inhibit expression of costimulatory molecules, production of inflammatory cytokines and NO of DCs by LPS. In addition, CCAs inhibit T cell proliferation by DCs activated with LPS. In vivo, CCA administration reduced blood proinflammatory cytokines and improved mice survival following LPS challenge. Considering functional impairment of DCs in sepsis patients, protecting DCs from hyperactivation by LPS might be crucial in the physiological outcome of sepsis. Taken together, CCA might mitigate the development of severe sepsis.

Enhancement of dendritic cell-based vaccine potency by anti-apoptotic siRNAs targeting key pro-apoptotic proteins in cytotoxic CD8(+) T cell-mediated cell death

Dendritic cells (DCs) have become an important measure for the treatment of malignancies. Current DC preparations, however, generate short-lived DCs because they are subject to cell death from various apoptotic pressures. Antigen-specific CD8(+) cytotoxic T lymphocytes (CTLs) is one of the main obstacles to limit the DC-mediated immune priming since CTLs can recognize the target antigen expressing DCs as target cells and kill the DCs. CTLs secret perforin and serine protease granzymes during CTL killing. Perforin and serine protease granzymes induce the release of a number of mitochondrial pro-apoptotic factors, which are controlled by members of the BCL-2 family, such as BAK, BAX and BIM. FasL linking to Fas on DCs triggers the activation of caspase-8, which eventually leads to mitochondria-mediated apoptosis via truncation of BID. In this study, we tried to enhance the DC priming capacity by prolonging DC survival using anti-apoptotic siRNA targeting these key pro-apoptotic molecules in CTL killing. Human papillomavirus (HPV)-16 E7 antigen presenting DCs that were transfected with these anti-apoptotic siRNAs showed increased resistance to T cell-mediated death, leading to enhanced E7-specific CD8(+) T cell activation in vitro and in vivo. Among them, siRNA targeting BIM (siBIM) generated strongest E7-specific E7-specific CD8(+) T cell immunity. More importantly, vaccination with E7 presenting DCs transfected with siBIM was capable of generating a marked therapeutic effect in vaccinated mice. Our data indicate that ex vivo manipulation of DCs with siBIM may represent a plausible strategy for enhancing dendritic cell-based vaccine potency.

Apolipoproteins inhibit the innate immunity activated by necrotic cells or bacterial endotoxin

We suggested earlier that the hydrophobic portions (Hyppos) of molecules, which are normally embedded in the membranes of cells or the core of molecular structures so as to be separated from the aqueous environment, might serve as evolutionarily ancient alarm signals of injury or stress to initiate innate immune responses when they are exposed on the surface. Under normal physiological conditions, the Hyppos released from endogenous or exogenous sources might be handled by 'Hyppo-quenchers'in vivo to maintain the tissue homeostasis and immune modulation. To test this idea, we selected apolipoproteins, which have been known to transport blood lipids and play a role in a number of pathological inflammatory conditions. We examined their role as Hyppo-quenchers in early immune responses and found that apolipoproteins showed significant inhibition of the nuclear factor-kappaB-dependent gene expression in recombinant Chinese hamster ovary (CHO) cells and dendritic cells stimulated by necrotic cells or bacterial endotoxin. In addition, our results indicate that apolipoproteins could dramatically abrogate complement fixation on the surface of necrotic cells. These findings suggest that apolipoproteins, besides having known functions in lipid metabolism, also have a role in preventing the initiation of innate immunity, potentially through neutralizing Hyppos from injured cells or exogenous endotoxin.

Role of amphipathic helix of a herpesviral protein in membrane deformation and T cell receptor downregulation

Lipid rafts are membrane microdomains that function as platforms for signal transduction and membrane trafficking. Tyrosine kinase interacting protein (Tip) of T lymphotropic Herpesvirus saimiri (HVS) is targeted to lipid rafts in T cells and downregulates TCR and CD4 surface expression. Here, we report that the membrane-proximal amphipathic helix preceding Tip's transmembrane (TM) domain mediates lipid raft localization and membrane deformation. In turn, this motif directs Tip's lysosomal trafficking and selective TCR downregulation. The amphipathic helix binds to the negatively charged lipids and induces liposome tubulation, the TM domain mediates oligomerization, and cooperation of the membrane-proximal helix with the TM domain is sufficient for localization to lipid rafts and lysosomal compartments, especially the mutivesicular bodies. These findings suggest that the membrane-proximal amphipathic helix and TM domain provide HVS Tip with the unique ability to deform the cellular membranes in lipid rafts and to downregulate TCRs potentially through MVB formation.

Anti-inflammatory effects of 8-hydroxydeoxyguanosine in LPS-induced microglia activation: suppression of STAT3-mediated intercellular adhesion molecule-1 expression

To elucidate the roles of 8-hydroxydeoxyguanosine (oh(8)dG), the nucleoside of 8-hydroxyguanine (oh(8)Gua), we examined the effects of oh(8)dG upon LPS-induced intercellular adhesion molecule-1 (ICAM-1) expression and the underlying mechanisms in brain microglial cells. We found that oh(8)dG reduces LPS-induced reactive oxygen species (ROS) production, STAT3 activation, and ICAM-1 expression. oh(8)dG also suppresses pro-inflammatory cytokines, such as TNF-alpha, IL-6 and IFN-gamma. Overexpression of dominant negative STAT3 completely diminshed STAT3-mediated ICAM-1 transcriptional activity. Chromatin immunoprecipitation studies revealed that oh(8)dG inhibited recruitment of STAT3 to the ICAM-1 promoter, followed by a decrease in ICAM-1 expression. Using mice lacking a functional Toll-like receptor 4 (TLR4), we demonstrated that, while TLR4+/+ microglia were activated by LPS, TLR4-/- microglia exhibited inactivated STAT3 in response to LPS. Evidently, LPS modulates STAT3-dependent ICAM-1 induction through TLR4-mdiated cellular responses. Oh(8)dG apparently plays a role in anti-inflammatory actions via suppression of ICAM-1 gene expression by blockade of the TLR4-STAT3 signal cascade in inflammation-enhanced brain microglia. Therefore, oh(8)dG in the cytosol probably functions as an anti-inflammatory molecule and should be considered as a candidate for development of anti-inflammatory agents.

Chemokine and cytokine production in susceptible C3H/HeN mice and resistant BALB/c mice during Orientia tsutsugamushi infection

To understand the pathogenesis of scrub typhus, we examined chemokine and cytokine production in susceptible (C3H/HeN) and resistant (BALB/c) mice after infection with O. tsutsugamushi Gilliam. C3H/HeN mice produced high levels of chemokines macrophage inflammatory proteins 1 alpha (MIP-1 alpha ), MIP-2, monocyte chemoattractant protein 1 (MCP-1), and cytokines gamma-interferon (IFN-gamma ), interleukin-12 (IL-12), IL-10, and tumor necrosis factor alpha (TNF-alpha ) in response to O. tsutsugamushi infection, compared to BALB/c mice. Chemokine profiles in infected mice correlated well with the kinetics of inflammatory cell infiltration. Hyperproduction of chemokines and cytokines was observed in another susceptible-infection model (BALB/c-Karp). These results suggest that hyperproduction of chemokines and cytokines are associated with susceptibility during O. tsutsugamushi infection.

Down-regulation of gp96 by Orientia tsutsugamushi

gp96 plays a central role in innate as well as acquired immunity, maturation and chemotaxis of dendritic cells, Ab production, and cross-priming, and is a peptide acceptor in endoplasmic reticulum and an accessory to peptide loading of MHC class I molecules. The remarkable conservation of essential immunological properties of gp96 suggests their important roles during the evolution of the immune system. Considering their importance in immunity, immune evasion mechanisms of pathogens by modulating gp96 expression have been speculated. By differential display PCR, we observed that obligate intracellular bacteria, Orientia tsutsugamushi, inhibit gp96 expression of a macrophage cell line, J774A.1. Not only gp96 transcripts but also protein was lower than for null-infected cells. The down-regulation was also consistent in an endothelial cell line, HMEC-1, and in murine peritoneal cells. These data support the idea that gp96 may be one of the target molecules for the immune evasion by intracellular bacteria.