Interleukin-33 Signaling Controls the Development of Iron-Recycling Macrophages.

Splenic red pulp macrophages (RPMs) contribute to erythrocyte homeostasis and are required for iron recycling. Heme induces the expression of SPIC transcription factor in monocyte-derived macrophages and promotes their differentiation into RPM precursors, pre-RPMs. However, the requirements for differentiation into mature RPMs remain unknown. Here, we have demonstrated that interleukin (IL)-33 associated with erythrocytes and co-cooperated with heme to promote the generation of mature RPMs through activation of the MyD88 adaptor protein and ERK1/2 kinases downstream of the IL-33 receptor, IL1RL1. IL-33- and IL1RL1-deficient mice showed defective iron recycling and increased splenic iron deposition. Gene expression and chromatin accessibility studies revealed a role for GATA transcription factors downstream of IL-33 signaling during the development of pre-RPMs that retained full potential to differentiate into RPMs. Thus, IL-33 instructs the development of RPMs as a response to physiological erythrocyte damage with important implications to iron recycling and iron homeostasis.

T cells selectively filter oscillatory signals on the minutes timescale.

T cells experience complex temporal patterns of stimulus via receptor-ligand-binding interactions with surrounding cells. From these temporal patterns, T cells are able to pick out antigenic signals while establishing self-tolerance. Although features such as duration of antigen binding have been examined, our understanding of how T cells interpret signals with different frequencies or temporal stimulation patterns is relatively unexplored. We engineered T cells to respond to light as a stimulus by building an optogenetically controlled chimeric antigen receptor (optoCAR). We discovered that T cells respond to minute-scale oscillations of activation signal by stimulating optoCAR T cells with tunable pulse trains of light. Systematically scanning signal oscillation period from 1 to 150 min revealed that expression of CD69, a T cell activation marker, reached a local minimum at a period of ∼25 min (corresponding to 5 to 15 min pulse widths). A combination of inhibitors and genetic knockouts suggest that this frequency filtering mechanism lies downstream of the Erk signaling branch of the T cell response network and may involve a negative feedback loop that diminishes Erk activity. The timescale of CD69 filtering corresponds with the duration of T cell encounters with self-peptide-presenting APCs observed via intravital imaging in mice, indicating a potential functional role for temporal filtering in vivo. This study illustrates that the T cell signaling machinery is tuned to temporally filter and interpret time-variant input signals in discriminatory ways.

TRIM2, a novel member of the antiviral family, limits New World arenavirus entry.

Tripartite motif (TRIM) proteins belong to a large family with many roles in host biology, including restricting virus infection. Here, we found that TRIM2, which has been implicated in cases of Charcot-Marie-Tooth disease (CMTD) in humans, acts by blocking hemorrhagic fever New World arenavirus (NWA) entry into cells. We show that Trim2-knockout mice, as well as primary fibroblasts from a CMTD patient with mutations in TRIM2, are more highly infected by the NWAs Junín and Tacaribe virus than wild-type mice or cells are. Using mice with different Trim2 gene deletions and TRIM2 mutant constructs, we demonstrate that its antiviral activity is uniquely independent of the RING domain encoding ubiquitin ligase activity. Finally, we show that one member of the TRIM2 interactome, signal regulatory protein α (SIRPA), a known inhibitor of phagocytosis, also restricts NWA infection and conversely that TRIM2 limits phagocytosis of apoptotic cells. In addition to demonstrating a novel antiviral mechanism for TRIM proteins, these studies suggest that the NWA entry and phagocytosis pathways overlap.

Wogonoside attenuates the articular cartilage injury and the infiltration of Th1/Th2-type cytokines in papain-induced osteoarthritis in rat model via inhibiting the NF-κB and ERK1/2 activation.

OBJECTS: Osteoarthritis is the most common joint disease and a major cause of functional limitation and pain in adults. This study aims to investigate the effect of wogonoside (WOG) on the progression of knee osteoarthritis (KOA) in model rats. MATERIALS AND METHODS: Rats KOA models were established and treated with different doses of WOG (10 mg/kg, 20 mg/kg and 30 mg/kg). The degree of cartilage injury was detected by Mankin scores via HE/Alcian blue staining. The levels of IFN-γ and IL-4 in peripheral blood and synovial fluid and the Th1/Th2 ratio were detected by flow cytometry. The model mice were injected with NF-κB p65 or ERK1/2 inhibitors or activators to further investigate the effect of WOG on KOA. RESULTS: WOG significantly improved cartilage tissue damage and reduced the Mankins score. WOG down-regulated the level of IFN-γ while up-regulated the expression of IL-4, which maintained the balance of Th1/Th2 cells. Further studies showed that the expression of NF-κB p65, phosphorylated p65, cytoplasmic ERK1/2 and nuclear ERK1/2 were all inhibited by WOG. The results of reverse verification experiments showed that the activator of NF-κB p65 and ERK1/2 weakened the protective effect of WOG on KOA, and the inhibitor of NF-κB p65ERK1/2 enhanced the protective effect of WOG on KOA. CONCLUSIONS: WOG inhibited the activation of NF-κB and ERK1/2 to alleviate the articular cartilage injury and Th1/th2 cytokine infiltration in KOA rats.

The inhibition of Src kinase suppresses the production of matrix metalloproteinases in from synovial fibroblasts and inhibits MAPK and STATs pathways

Background/aim: The purpose of this study was to investigate the antiarthritic potentials of the inhibition of Src kinase in vivo and in vitro settings. Materials and methods: Arthritis was induced by intradermal injection of chicken type II collagen combined with incomplete Freund's adjuvant (collagen induced arthritis [CIA] model) in Wistar albino rats. One day after the onset of arthritis, dasatinib, a potent Src kinase inhibitor, (5 mg/kg/day) was given via oral gavage. Tissue Src, Fyn, MAPK and STAT mRNA expressions were determined by real-time polymerase chain reaction. On the other hand, fibroblast like synoviocytes (FLSs) were harvested patients with rheumatoid arthritis (RA) undergoing surgical knee joint replacement. FLSs were stimulated with cytokines and dasatinib was added in different concentrations. MMP ­1, ­3, and ­13 levels in FLSs culture were determined by ELISA. Results: The tissue mRNA expressions of Src, Fyn, MAPK and STATs were increased in the arthritis CIA group compared to the control group. Their mRNA expressions in the CIA + dasatinib group were decreased and similar in the control group. In in vitro setting, MMP ­1, ­3, and ­13 expressions from FLSs induced by IL-1ß and TNF-α were increased, while dasatinib suppressed their productions from FLSs. Conclusion: The present study shows that the inhibition of Src kinase has antiarthritic potentials in both in vivo and in vitro settings. Src kinase inhibition may be candidate to further research in human RA.

Serum ERK1/2 proteins fluctuating with HBV infection report frequency of viral-specific CD8+ T cells and predict IFNα therapeutic effect in chronic hepatitis B patients.

Chronic hepatitis B (CHB) is a life-threatening disease caused by HBV infection. Our previous work proved that activation of ERK1/2 and STAT3 signaling was involved in HBV tolerance. We herein investigated clinical significances of serum ERK1/2 and STAT3 proteins in CHB. Results showed that ERK1/2 and STAT3 were fluctuated with natural history of CHB. In addition, STAT3 was found to be positively correlated to the elevation of ALT, AST and GGT, while ERK1 was negatively correlated to decreases of TP and ALB. Also, there was a positive correlation between the anti-HBc antibody and ERK1, ERK2 or STAT3 in HBeAg-negative patients. Strikingly, serum ERK1 and ERK2 could reflect level of HBsAg-specific CD8+ T cells. A model composed with baseline ERK1 and ERK2 levels had a high accuracy to predict the effect of IFNα treatment. In conclusion, serum ERK1, ERK2 and STAT3 could serve as novel biomarkers in chronic HBV infections.

Lactic acid suppresses IgE-mediated mast cell function in vitro and in vivo.

Mast cells have functional plasticity affected by their tissue microenvironment, which greatly impacts their inflammatory responses. Because lactic acid (LA) is abundant in inflamed tissues and tumors, we investigated how it affects mast cell function. Using IgE-mediated activation as a model system, we found that LA suppressed inflammatory cytokine production and degranulation in mouse peritoneal mast cells, data that were confirmed with human skin mast cells. In mouse peritoneal mast cells, LA-mediated cytokine suppression was dependent on pH- and monocarboxylic transporter-1 expression. Additionally, LA reduced IgE-induced Syk, Btk, and ERK phosphorylation, key signals eliciting inflammation. In vivo, LA injection reduced IgE-mediated hypothermia in mice undergoing passive systemic anaphylaxis. Our data suggest that LA may serve as a feedback inhibitor that limits mast cell-mediated inflammation.

HIV-1 infection modulates IL-24 expression which contributes to cell apoptosis in vitro.

Although interleukin-24 (IL-24) has been extensively explored in the immunopathologies of autoimmune diseases, neoplasms, and infections, its role in HIV-1 infection has not been thoroughly elucidated to date. Therefore, the objective of this study was to evaluate the gene and protein expressions of IL-24 at the initial moments of HIV infection in PBMCs. Due to the pro-apoptotic role of IL-24, we evaluated the protein expression of caspase-3, as well as Annexin V/Propidium Iodide flow cytometry and phosphorylation of ERK, which may induce an apoptotic signal block when phosphorylated. The results of this study demonstrated that HIV-1 infection had an impact on the gene and protein expressions of IL-24 and ERK. Annexin V/Propidium Iodide assay demonstrated decrease in the mechanisms of apoptosis in infected cells after incubation of IL-24 neutralizing antibody. Studies on how HIV-1 regulates IL-24 expression may play a role in characterizing viral persistence mechanisms and designing antiretroviral strategies.

Silica nanoparticles as an enhancer in the IL-1ß-induced inflammation cycle of A549 cells.

Objective: The industrial production and combustion of coal can produce silica nanoparticles (nano-SiO2). It enters the human body mainly through the respiratory tract and exerts a toxic effect. However, whether nano-SiO2 can increase the IL-1ß-induced inflammatory expression in A549 cells has not been tested. Therefore, the synergistic toxicity of nano-SiO2 and IL-1ß to A549 was observed in our study. Materials and methods: We exposed A549 cells to nano-SiO2 (0, 100, 500, and 1000 µg/ml) for 12 and 24 h. The effect of nano-SiO2 on the viability of A549 cells was observed by the CCK-8 method. The A549 cells were exposed to nano-SiO2 (1 mg/mL) and cytokine IL-1ß (10 ng/mL) for 4 h, and we detected the expression of IL-1ß and IL-6 cytokines by real time quantitative polymerase chain (RT-qPCR) and enzyme linked immunosorbent assay (ELISA). The expression of ß-Actin, I-κB, phospho-ERK1/2 (P-ERK1/2), total-ERK1/2 (T-ERK1/2), phospho-JNK (P-JNK), total-JNK (T-JNK), phospho-P38 (P-P38), and total-P38 (T-P38) in A549 cells was detected by the Western Blot method. Results: The nano-SiO2 treatment resulted in a time-dependent decrease in the viability of A549 cells. The synergistic effect of nano-SiO2 and IL-1ß was observed on the new production of IL-1ß and IL-6 in A549 cells. The Western blot results showed that nano-SiO2 can increase the expression of IL-1ß and IL-6 by promoting the phosphorylation of ERK1/2 and elevating the phosphorylation of I-κB by IL-1ß. IL-1ß and IL-6 were induced by nano-SiO2, and the IL-1ß treatment with 20 µM of I-κBα phosphorylation inhibitor (PD98059) and 20 µM of ERK1/2 inhibitor (BAY11-7082) for 1 h was significantly lower than that of the control group in A549 cells. Discussion and conclusion: These results indicated that nano-SiO2 had a toxic effect on A549 cells, and this effect could increase IL-1ß on the A549 cell-induced inflammatory response. The results suggested that the release of IL-1ß and IL-6 in A549 was enhanced by the synergistic IL-1ß-induced phosphorylation of ERK1/2 and I-κB. This process is similar to a snowball, and it is possible that IL-1ß is continuously produced and repeatedly superimposed in A549 cells to produce an inflammatory effect; then, a vicious circle occurs, and an inflammatory storm is accelerated.

PM2.5 upregulates rat mesenteric arteries 5-HT2A receptor via inflammatory-mediated mitogen-activated protein kinases signaling pathway.

Fine particulate matter (PM2.5 ) is an important environmental risk factor for cardiovascular diseases. However, little is known about the effects of PM2.5 on arteries. The present study investigated whether PM2.5 alters 5-hydroxytryptamine (5-HT) receptor expression and inflammatory mediators on rat mesenteric arteries, and examined the underlying mechanisms. Isolated rat mesenteric arteries segments were cultured with PM2.5 in the presence or absence of ERK1/2, JNK, and p38 pathway inhibitors. Contractile reactivity was monitored by a sensitive myograph. The expression of 5-HT2A/1B receptors and inflammatory mediators were studied by a real-time polymerase chain reaction and/or by immunohistochemistry. The phosphorylation of mitogen-activated protein kinases (MAPK) pathway was detected by Western blot. Compared with the fresh or culture alone groups, 1.0 µg/mL PM2.5 cultured for 16 hours significantly enhanced contractile response induced by 5-HT and increased 5-HT2A receptor mRNA and protein expressions, indicating PM2.5 upregulates 5-HT2A receptor. SB203580 (p38 inhibitor) and U0126 (ERK1/2 inhibitor) significantly decreased PM2.5 -induced elevated contraction and mRNA and protein expression of 5-HT2A receptor. Cultured with PM2.5 significantly increased the mRNA expression of inflammatory mediators (NOS2, IL-1ß, and TNF-α), while SB203580 decreased mRNA expression level of NOS2, IL-1ß, and TNF-α. SP600125 (JNK inhibitor) decreased mRNA expression level of TNF-α and IL-1ß. After PM2.5 exposure, the phosphorylation of p38 and ERK1/2 protein were increased. SB203580 and U0126 inhibited the PM2.5 caused increased phosphorylation protein of p38 and ERK1/2. In conclusion, PM2.5 induces inflammatory-mediated MAPK pathway in artery which subsequently results in enhanced vascular contraction responding to 5-HT via the upregulated 5-HT2A receptors.

Role of Signaling Molecules in the Regulation of Granulocytopoiesis during Stress-Inducing Stimulation.

The role of signaling molecules in synthesis of humoral regulators of granulocytopoiesis by the hematopoietic microenvironmental cells during stress was analyzed using specific inhibitors. The major role in stimulation of the synthesis of granulocytic CSF during stressful stimulation is played by PI3K/Akt signaling cascade. Nuclear transcription factor NF-κB plays an auxiliary role in the regulation of functional activity of the bone marrow mononuclears. However, this factor affects the synthesis of granulocytic CSF by CD4+ cells of the bone marrow in response to stressful stimulation. Different degree and specific character of involvement of the signaling proteins in the regulation of the production of humoral factors determining colony-stimulating activity are explained by changes in functional state of monocyte-derived macrophages in different periods of stress response.

NF-κB inducing kinase (NIK) is an essential post-transcriptional regulator of T-cell activation affecting F-actin dynamics and TCR signaling.

NF-κB inducing kinase (NIK) is the key protein of the non-canonical NF-κB pathway and is important for the development of lymph nodes and other secondary immune organs. We elucidated the specific role of NIK in T cells using T-cell specific NIK-deficient (NIKΔT) mice. Despite showing normal development of lymphoid organs, NIKΔT mice were resistant to induction of CNS autoimmunity. T cells from NIKΔT mice were deficient in late priming, failed to up-regulate T-bet and to transmigrate into the CNS. Proteomic analysis of activated NIK-/- T cells showed de-regulated expression of proteins involved in the formation of the immunological synapse: in particular, proteins involved in cytoskeleton dynamics. In line with this we found that NIK-deficient T cells were hampered in phosphorylation of Zap70, LAT, AKT, ERK1/2 and PLCγ upon TCR engagement. Hence, our data disclose a hitherto unknown function of NIK in T-cell priming and differentiation.

Spontaneous chondroma formation in CD2-Cre-driven Erk-deficient mice.

Lineage-specific Cre Tg mice are widely used to delineate the functions of genes in a tissue-specific manner. Several T-cell-specific promoter cassettes have been developed; however, the activities of those promoters in non-T cells have not been investigated extensively. Here, we report that CD2-Cre-mediated deletion of Erk proteins by generating CD2-Cre × Erk1-/-Erk2flox/flox (Erk∆CD2-Cre) mice results in abnormal cartilage hyperplasia. Histological analysis revealed that this abnormality is caused by aberrant hyperplasia of chondrocytes. The presence of Erk-deficient T cells is not required for this chondroma formation, as it was similarly observed in the absence of T cells in a CD3ε-deficient background. In addition, adoptive transfer of bone marrow cells from Erk∆CD2-Cre mice to wild-type recipients did not cause chondroma formation, suggesting that Erk-deficient non-immune cells are responsible for this abnormality. By tracing Cre-expressed tissues using a ROSA26-STOP-RFP allele, we found that the chondroma emitted RFP fluorescence, indicating that functional Cre is expressed in hyperplastic chondrocytes in Erk∆CD2-Cre mice. Furthermore, RFP+ chondrocytes were also found in an Erk-sufficient background, albeit without aberrant growth. These results suggest that unexpected expression of CD2-driven Cre in chondrocytes generates Erk-deficient chondrocytes, resulting in hyperplastic cartilage formation. Recently, two independent reports showed that CD4-Cre-mediated Ras-Erk signaling ablation led to similar abnormal cartilage formation (Guittard, G., Gallardo, D. L., Li, W. et al. 2017. Unexpected cartilage phenotype in CD4-Cre-conditional SOS-deficient mice. Front. Immunol. 8:343; Wehenkel, M., Corr, M., Guy, C. S. et al. 2017. Extracellular signal-regulated kinase signaling in CD4-expressing cells inhibits osteochondromas. Front. Immunol. 8:482). Together with these reports, our study suggests that an unexpected link exists between T-like cell and chondrocyte lineages during ontogeny.

Imbalanced signal transduction in regulatory T cells expressing the transcription factor FoxP3.

FoxP3(+) T regulatory (Treg) cells have a fundamental role in immunological tolerance, with transcriptional and functional phenotypes that demarcate them from conventional CD4(+) T cells (Tconv). Differences between these two lineages in the signaling downstream of T-cell receptor-triggered activation have been reported, and there are different requirements for some signaling factors. Seeking a comprehensive view, we found that Treg cells have a broadly dampened activation of several pathways and signaling nodes upon TCR-mediated activation, with low phosphorylation of CD3ζ, SLP76, Erk1/2, AKT, or S6 and lower calcium flux. In contrast, STAT phosphorylation triggered by interferons, IL2 or IL6, showed variations between Treg and Tconv in magnitude or choice of preferential STAT activation but no general Treg signaling defect. Much, but not all, of the Treg/Tconv difference in TCR-triggered responses could be attributed to lower responsiveness of antigen-experienced cells with CD44(hi) or CD62L(lo) phenotypes, which form a greater proportion of the Treg pool. Candidate regulators were tested, but the Treg/Tconv differential could not be explained by overexpression in Treg cells of the signaling modulator CD5, the coinhibitors PD-1 and CTLA4, or the regulatory phosphatase DUSP4. However, transcriptome profiling in Dusp4-deficient mice showed that DUSP4 enhances the expression of a segment of the canonical Treg transcriptional signature, which partially overlaps with the TCR-dependent Treg gene set. Thus, Treg cells, likely because of their intrinsically higher reactivity to self, tune down TCR signals but seem comparatively more attuned to cytokines or other intercellular signals.

Anti-Inflammatory Effect of Melittin on Porphyromonas Gingivalis LPS-Stimulated Human Keratinocytes.

Periodontitis is a chronic inflammatory disease that contributes to the destruction of the gingiva. Porphyromonas gingivalis (P. gingivalis) can cause periodontitis via its pathogenic lipopolysaccharides (LPS). Melittin, a major component of bee venom, is known to have anti-inflammatory and antibacterial effects. However, the role of melittin in the inflammatory response has not been elucidated in periodontitis-like human keratinocytes. Therefore, we investigated the anti-inflammatory effects of melittin on a P. gingivalis LPS (PgLPS)-treated HaCaT human keratinocyte cell line. The cytotoxicity of melittin was measured using a human keratinocyte cell line, HaCaT, and a Cell Counting Kit-8. The effect of melittin on PgLPS-induced inflammation was determined with Western blot, real-time quantitative PCT, and immunofluorescence. PgLPS increased the expression of toll-like receptor (TLR) 4 and proinflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-8, and interferon-γ (IFN-γ). Moreover, PgLPS induced activation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), extracellular signal-regulated kinase (ERK), and protein kinase B/Akt. Melittin also inhibited the expression of proinflammatory cytokines by suppressing the activation of the NF-κB signaling pathway, ERK, and Akt. Melittin attenuates the PgLPS-induced inflammatory response and could therefore be applied in the treatment of periodontitis for anti-inflammatory effects.

Ras-related C3 Botulinum Toxin Substrate (Rac) and Src Family Kinases (SFK) Are Proximal and Essential for Phosphatidylinositol 3-Kinase (PI3K) Activation in Natural Killer (NK) Cell-mediated Direct Cytotoxicity against Cryptococcus neoformans.

The activity of Rac in leukocytes is essential for immunity. However, its role in NK cell-mediated anti-microbial signaling remains unclear. In this study, we investigated the role of Rac in NK cell mediated anti-cryptococcal killing. We found thatCryptococcus neoformansindependently activates both Rac and SFK pathways in NK cells, and unlike in tumor killing,Cryptococcusinitiated a novel Rac → PI3K → Erk cytotoxicity cascade. Remarkably, Rac was not required for conjugate formation, despite its essential role in NK cytotoxicity againstC. neoformans Taken together, our data show that, unlike observations with tumor cells, NK cells use a novel Rac cytotoxicity pathway in conjunction with SFK, to killC. neoformans.

Prostaglandins from Cytosolic Phospholipase A2α/Cyclooxygenase-1 Pathway and Mitogen-activated Protein Kinases Regulate Gene Expression in Candida albicans-infected Macrophages.

In Candida albicans-infected resident peritoneal macrophages, activation of group IVA cytosolic phospholipase A2(cPLA2α) by calcium- and mitogen-activated protein kinases triggers the rapid production of prostaglandins I2 and E2 through cyclooxygenase (COX)-1 and regulates gene expression by increasing cAMP. InC. albicans-infected cPLA2α(-/-)or COX-1(-/-)macrophages, expression ofI l10,Nr4a2, and Ptgs2 was lower, and expression ofTnfα was higher, than in wild type macrophages. Expression was reconstituted with 8-bromo-cAMP, the PKA activator 6-benzoyl-cAMP, and agonists for prostaglandin receptors IP, EP2, and EP4 in infected but not uninfected cPLA2α(-/-)or COX-1(-/-)macrophages. InC. albicans-infected cPLA2α(+/+)macrophages, COX-2 expression was blocked by IP, EP2, and EP4 receptor antagonists, indicating a role for both prostaglandin I2 and E2 Activation of ERKs and p38, but not JNKs, by C. albicansacted synergistically with prostaglandins to induce expression of Il10,Nr4a2, and Ptgs2. Tnfα expression required activation of ERKs and p38 but was suppressed by cAMP. Results using cAMP analogues that activate PKA or Epacs suggested that cAMP regulates gene expression through PKA. However, phosphorylation of cAMP-response element-binding protein (CREB), the cAMP-regulated transcription factor involved inIl10,Nr4a2,Ptgs2, andTnfα expression, was not mediated by cAMP/PKA because it was similar inC. albicans-infected wild type and cPLA2α(-/-)or COX-1(-/-)macrophages. CREB phosphorylation was blocked by p38 inhibitors and induced by the p38 activator anisomycin but not by the PKA activator 6-benzoyl-cAMP. Therefore, MAPK activation inC. albicans-infected macrophages plays a dual role by promoting the cPLA2α/prostaglandin/cAMP/PKA pathway and CREB phosphorylation that coordinately regulate immediate early gene expression.

Impairment of Hematopoietic Precursor Cell Activation during the Granulopoietic Response to Bacteremia in Mice with Chronic-Plus-Binge Alcohol Administration.

Alcohol abuse impairs immune defense. To study the effect of chronic-plus-binge alcohol exposure on the granulopoietic response, acute alcohol intoxication (intraperitoneal injection of 5 g alcohol/kg body weight) was introduced to mice chronically fed on the Lieber-DeCarli low-fat liquid alcohol diet for 5 weeks. Bacteremia was induced by intravenous injection of Escherichia coli Bacteremia caused a remarkable increase in marrow lin- c-kit+ Sca-1+ cells. Activation of cell proliferation supported the increase in marrow lin- c-kit+ Sca-1+ cells. Alcohol administration inhibited this activation of lin- c-kit+ Sca-1+ cells. The bone marrow of pair-fed control mice receiving intraperitoneal saline stored a large number of mature granulocytes expressing a high level of Gr1 (Gr1hi cells). The proportion of Gr1hi cells and the total number of Gr1+ cells were markedly reduced in the bone marrow, along with an increase in the ratio of Gr1+ granulocytes in peripheral white blood cells following bacteremia. E. coli infection stimulated proliferation of granulopoietic precursor cells, resulting in a marked increase in the ratio of immature Gr1lo cells in the bone marrow. Alcohol administration itself triggered marrow release of Gr1+ cells, resulting in reduction of the marrow granulocyte reserve with an elevation of granulocytes in the circulation. Alcohol also impaired activation of granulopoietic precursor proliferation following bacteremia. Alcohol disrupted lipopolysaccharide (LPS)-TLR4-ERK1/2-cyclin D1 signaling and inhibited upregulation of Sca-1 and C/EBPß expression by lineage-negative marrow cells in response to bacteremia. These results indicate that chronic-plus-binge alcohol exposure inhibits the granulopoietic response by disrupting key cell signaling for hematopoietic precursor cell activation and commitment to granulocyte lineage development.

Peripheral Lipopolysaccharide Challenge Induces Long-Term Changes in Tyrosine Hydroxylase Regulation in the Adrenal Medulla.

Immune activation can alter the activity of adrenal chromaffin cells. The effect of immune activation by lipopolysaccharide (LPS) on the regulation of tyrosine hydroxylase (TH) in the adrenal medulla in vivo was determined between 1 day and 6 months after LPS injection. The plasma levels of eleven cytokines were reduced 1 day after LPS injection, whereas the level for interleukin-10 was increased. The levels of all cytokines remained at control levels until 6 months when the levels of interleukin-6 and -4 were increased. One day after LPS injection, there was a decrease in TH-specific activity that may be due to decreased phosphorylation of serine 31 and 40. This decreased phosphorylation of serine 31 and 40 may be due to an increased activation of the protein phosphatase PP2A. One week after LPS injection, there was increased TH protein and increased phosphorylation of serine 40 that this was not accompanied by an increase in TH-specific activity. All TH parameters measured returned to basal levels between 1 month and 3 months. Six months after injection there was an increase in TH protein. This was associated with increased levels of the extracellular regulated kinase isoforms 1 and 2. This work shows that a single inflammatory event has the capacity to generate both short-term and long-term changes in TH regulation in the adrenal medulla of the adult animal. J. Cell. Biochem. 118: 2096-2107, 2017. © 2016 Wiley Periodicals, Inc.

Angiotensin II Regulates Dendritic Cells through Activation of NF-κB /p65, ERK1/2 and STAT1 Pathways.

BACKGROUND: Activation of dendritic cells (DCs) is necessary to initiate immune responses. Angiotensin II (Ang II) has been reported to have a proinflammatory and immunomodulatory function. However, the role of Ang II in regulation of DCs and the underlying mechanisms remain illdefined. METHODS: The effects of Ang II on the proliferation, maturation, phagocytosis, migration, and communication with T cells of DCs were analysed utilizing MTT, flow cytometry, ELISA, transwell assay and mixed lymphocyte culture. RESULTS: We found that Ang II treatment significantly inhibited proliferation and phagocytic activity of DCs, but promoted the DC maturation and migration well as the expression of pro-inflammatory cytokines by DCs. In addition, Ang II also stimulated DC-mediated T cell proliferation. These effects were associated with activation of p65/NF-κB, ERK1/2 and STAT1 signaling pathways in DCs. CONCLUSIONS: Our results demonstrate that Ang II activates DCs partially through p65/NF-κB, ERK1/2 and STAT1 pathways, and suggest a potential therapeutic target of DC-mediated inflammatory disorders.