• IMMUNE NETWORK
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• v.8 no.1
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• pp.1-6
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• 2008

Apoptosis signal-regulating kinase 1 (ASK1), a mitogen- activated protein kinase kinase kinase, plays pivotal roles in stress responses. In addition, ASK1 has emerged as a key regulator of immune responses elicited by pathogen-associated molecular patterns (PAMPs) and endogenous danger signals. Recent studies have demonstrated that reactive oxygen species (ROS)-dependent activation of ASK1 is required for LPS-stimulated cytokine production as well as extracellular ATP-induced apoptosis in immune cells. The mechanism of ROS-dependent regulation of ASK1 activity by thioredoxin and TRAFs has been well characterized. In this review, we focus on the molecular details of the activation of ASK1 and its involvement in innate immunity.

• BMB Reports
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• v.46 no.7
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• pp.376-381
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• 2013

It is unknown how soluble pattern-recognition receptors in blood, such as mannose-binding lectin (MBL) and ficolins, modulate mast cell-mediated inflammatory responses. We investigate how mouse MBL-A or ficolin-A regulate mouse bone marrow-derived mast cells (mBMMCs)-derived inflammatory response against bacterial lipopolysaccharide (LPS) stimulation. LPS-mediated pro-inflammatory cytokine productions on mBMMCs obtained from Toll-like receptor4 (TLR4)-deficient mice, TLR2-defficient mice, and their wildtype, were specifically attenuated by the addition of either mouse MBL-A or ficolin-A in a dose-dependent manner. However, the inhibitory effects by mouse MBL-A or ficolin-A were restored by the addition of mannose or N-acetylglucosamine, respectively. These results suggest that mouse MBL-A and ficolin-A bind to LPS via its carbohydrate-recognition domain and fibrinogen-like domain, respectively, whereby cytokine production by LPS-mediated TLR4 in mBMMCs appears to be down-regulated, indicating that mouse MBL and ficolin may have an inhibitory function toward mouse TLR4-mediated excessive inflammation on the mast cells.

• Journal of Veterinary Science
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• v.24 no.5
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• pp.72.1-72.16
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• 2023

Background: Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) on the surface of Streptococcus dysgalactiae, coded with gapC, is a glycolytic enzyme that was reported to be a moonlighting protein and virulence factor. Objective: This study assessed GAPDH as a potential immunization candidate protein to prevent streptococcus infections. Methods: Mice were vaccinated subcutaneously with recombinant GAPDH and challenged with S. dysgalactiae in vivo. They were then evaluated using histological methods. rGAPDH of mouse bone marrow-derived dendritic cells (BMDCs) was evaluated using immunoblotting, reverse transcription quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay methods. Results: Vaccination with rGAPDH improved the survival rates and decreased the bacterial burdens in the mammary glands compared to the control group. The mechanism by which rGAPDH vaccination protects against S. dysgalactiae was investigated. In vitro experiments showed that rGAPDH boosted the generation of interleukin-10 and tumor necrosis factor-α. Treatment of BMDCs with TAK-242, a toll-like receptor 4 inhibitor, or C29, a toll-like receptor 2 inhibitor, reduced cytokines substantially, suggesting that rGAPDH may be a potential ligand for both TLR2 and TLR4. Subsequent investigations showed that rGAPDH may activate the phosphorylation of MAPKs and nuclear factor-κB. Conclusions: GAPDH is a promising immunization candidate protein for targeting virulence and enhancing immune-mediated protection. Further investigations are warranted to understand the mechanisms underlying the activation of BMDCs by rGAPDH in a TLR2- and TLR4-dependent manner and the regulation of inflammatory cytokines contributing to mastitis pathogenesis.

• Journal of Microbiology and Biotechnology
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• v.29 no.5
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• pp.704-712
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• 2019

Although nanometric dead Lactobacillus plantarum has emerged as a potentially important modulator of immune responses, its underlying mechanism of action has not been fully understood. This study aimed to identify the detailed biochemical mechanism of immune modulation by micronized and heat-treated L. plantarum LM1004 (MHT-LM1004, <$1{\mu}m$ in size). MHT-LM1004 was prepared from L. plantarum LM1004 via culture in a specifically designed membrane bioreactor and heat treatment. MHT-LM1004 was shown to effectively induce the secretion of $TNF-{\alpha}$ and IL-6 and the mRNA expression of inducible nitric oxide synthase (iNOS). MHT-LM1004 enhanced the expression of TLR-2, phosphorylation of MAPKs (ERK), and nuclear translocation of $NF-{\kappa}B$ in a dose-dependent manner. Oral administration of MHT-LM1004 ($4{\times}10^9$ or $4{\times}10^{11}cells/kg$ mouse body weight) increased the splenocyte proliferation and serum cytokine levels. These results suggested that MHT-LM1004 effectively enhances early innate immunity by activating macrophages via the TLR-2/MAPK/$NF-{\kappa}B$ signalling pathway and that this pathway is one of the major routes in immune modulation by the Lactobacillus species.

• Korean Journal of Poultry Science
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• v.40 no.2
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• pp.83-89
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• 2013

iNOS (Inducible nitric oxide synthase) and TLR-4 (Toll-like Receptor-4) play crucial roles in innate immunity of poultry. iNOS has been mapped to chicken chromosome 14 and implicated in a variety of chicken diseases. iNOS possesses potent antimicrobial activity, including the inhibition of microbes replication in vitro. TLR-4 is a pathogen associated molecular-pattern receptor for bacterial product, such as LPS (lipopolysaccharides) found in Gram negative bacteria, that triggers pro-inflammatory cytokine expression after engagement with ligands. In the previous studies, genetic analysis of iNOS and TLR-4 revealed the possible association of mutation in these genes with the intestinal microflora of cecum when infected with Salmonella spp. This study was aimed to augment previous findings, which show the association of iNOS (C14513T) and TLR-4 (G4409T) polymorphisms with economic traits in Korean Native Black (KNB), Rhode Island Red (RIR) and Cornish chickens. Investigation in the effect of SNPs on economic traits (layday, layw, layno, bw150, bw270, layw270) was conducted. iNOS (C14513T) had a significant effect on the average body weight at 270 days of age (p<0.05) in both KNB and RIR, whereas TLR-4 (G4409T) showed no significant correlation with all traits (p>0.05). The results obtained from using the candidate genes can be useful for the genetic improvement of body weight in both KNB and RIR breeds.

• Biomolecules & Therapeutics
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• v.24 no.6
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• pp.638-649
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• 2016

In the previous study, the rhizome mixture of Anemarrhena asphodeloides and Coptis chinensis (DW2007), improved TNBS-, oxazolone-, or DSS-induced colitis in mice by regulating macrophage activation. Therefore, to understand the effect of DW2007 on the T cell differentiation involved in the adaptive immunity, we measured its effect on both Th17 and Treg cell differentiation in splenocytes, in the lamina propria of mice with DSS-induced colitis (DIC), and in the spleens of mice with collagen-induced arthritis (CIA). Results showed that DW2007 potently inhibited the differentiation of splenocytes into Th17 cells, but increased Treg cell differentiation in vitro. In the colon of wild type and $TLR4^{-/-}$ mice with DIC, DW2007 potently suppressed DSS-induced colon shortening and myeloperoxidase activity. DW2007 also suppressed collagen-induced paw thickening, clinical index, and myeloperoxidase activity in CIA mice. Overall, DW2007 potently suppressed Th17 cell differentiation in mice with CIA and DIC, but increased Treg cell differentiation. Moreover, DW2007 strongly inhibited the expression of TNF-${\alpha}$ and IL-$1{\beta}$, as well as the activation of NF-${\kappa}B$. Based on these findings, DW2007 may ameliorate inflammatory diseases by regulating the innate immunity via the inhibition of macrophage activation and the adaptive immunity via the correction of disturbed Th17/Treg cells.

• IMMUNE NETWORK
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• v.13 no.5
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• pp.205-212
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• 2013

Dectin-1, which specifically recognizes ${\beta}$-glucan of fungal cell walls, is a non-Toll-like receptor (TLR) pattern recognition receptor and a representative of C-type lectin receptors (CLRs). The importance of Dectin-1 in innate immune cells, such as dendritic cells and macrophages, has previously been well studied. However, the function of Dectin-1 in B cells is very poorly understood. To determine the role of Dectin-1 in B cell activation, we first investigated whether mouse B cells express Dectin-1 and then assessed the effect of Dectin-1 stimulation on B cell proliferation and antibody production. Mouse B cells express mRNAs encoding CLRs, including Dectin-1, and surface Dectin-1 was expressed in B cells of C57BL/6 rather than BALB/c strain. Dectin-1 agonists, heat-killed Candida albicans (HKCA) and heat-killed Saccharomyces cerevisiae (HKSC), alone induced B cell proliferation but not antibody production. Interestingly, HKSC, HKCA, and depleted zymosan (a selective Dectin-1 agonist) selectively enhanced LPS-driven IgG1 production. Taken together, these results suggest that, during fungal infection, ${\beta}$-glucan-stimulated Dectin-1 may cooperate with TLR4 to specifically enhance IgG1 production by mouse B cells.

• IMMUNE NETWORK
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• v.21 no.6
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• pp.42.1-42.20
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• 2021

Eosinophils play critical roles in the maintenance of homeostasis in innate and adaptive immunity. Although primarily known for their roles in parasitic infections and the development of Th2 cell responses, eosinophils also play complex roles in other immune responses ranging from anti-inflammation to defense against viral and bacterial infections. However, the contributions of pattern recognition receptors in general, and NOD-like receptors (NLRs) in particular, to eosinophil involvement in these immune responses remain relatively underappreciated. Our in vivo studies demonstrated that NLRC4 deficient mice had a decreased number of eosinophils and impaired Th2 responses after induction of an allergic airway disease model. Our in vitro data, utilizing human eosinophilic EoL-1 cells, suggested that TLR2 induction markedly induced pro-inflammatory responses and inflammasome forming NLRC4 and NLRP3. Moreover, activation by their specific ligands resulted in caspase-1 cleavage and mature IL-1β secretion. Interestingly, Th2 responses such as secretion of IL-5 and IL-13 decreased after transfection of EoL-1 cells with short interfering RNAs targeting human NLRC4. Specific induction of NLRC4 with PAM3CSK4 and flagellin upregulated the expression of IL-5 receptor and expression of Fc epsilon receptors (FcεR1α, FcεR2). Strikingly, activation of the NLRC4 inflammasome also promoted expression of the costimulatory receptor CD80 as well as expression of immunoregulatory receptors PD-L1 and Siglec-8. Concomitant with NLRC4 upregulation, we found an increase in expression and activation of matrix metalloproteinase (MMP)-9, but not MMP-2. Collectively, our results present new potential roles of NLRC4 in mediating a variety of eosinopilic functions.

• Journal of Life Science
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• v.27 no.4
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• pp.482-499
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• 2017

Allergic diseases have increased over the past several decade worldwide including developing countries. Allergic inflammatory responses are caused by Th (T helper)2 immune responses, triggered by allergen ingestion by antigen presenting cells such as dendritic cells (DCs). Intestinal microorganisms control the metabolism and physiological functions of the host, contribute to early immune system maturation during the early life, and homeostasis and epithelial integrity during life. Bifidobacteria have strain-specific immunostimulatory properties in the Th1/Th2 balance, inhibit TSLP (thymic stromal lymphopoietin) and IgE expression, and promote Flg (Filaggrin) and FoxP3 (Treg) expression to alleviate allergies. In addition, unmethylated CpG motif ODN (oligodeoxynucleotides) is recognized by TLR (toll-like receptors)9 of B cells and plasmacytoid dendritic cells (pDCs) to induce innate and adaptive immune responses, while the butyrate produced by Clostridium butyricum activates the GPR (G-protein coupled receptors)109a signaling pathway to induce the expression of anti-inflammatory gene of pDCs, and directly stimulates the proliferation of thymically derived regulatory T (tTreg) cells through the activation of GPR43 or inhibits the activity of HADC (histone deacetylase) to differentiate naive $CD4^+$ T cells into pTreg cells through the histone H3 acetylation of Foxp3 gene intronic enhancer.