The Immunomodulatory Activity of C3 Binding Glycoprotein (C3bgp) is Mediated by the Complement Receptor Type III and Mitogen-Activated Protein Kinase Signal Transduction Pathways

Immune role of the complement component 6 gene and its associated novel miRNA, miR-727, in half-smooth tongue sole (Cynoglossus semilaevis)

The complement component 6 (C6) gene is a component of the membrane attack complex (MAC), which causes rapid lytic destruction of bacteria. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene stability, including that of immune genes. However, current research on the function of C6 and its regulation by miRNAs is lacking. In the present study, we identified and characterized C6 and a novel miRNA, miR-727 (designated CsC6 and Cse-miR-727, respectively), of the half-smooth tongue sole (Cynoglossus semilaevis) that responded to infection with Vibrio anguillarum, a Gram-negative pathogen of marine fish. The full-length cDNA of CsC6 contained a 256 bp 5' untranslated region (5'-UTR), a 2820 bp open reading frame (ORF) encoding 939 amino acids, and a 205 bp 3'-UTR. SMART analysis showed that CsC6 contains typical C6 domains, including three TSP1 domains, one LDLa domain, one MACPF domain, two CCP domains and two FIMAC domains. CsC6 and Cse-miR-727 are widely expressed in the 13 tissues of half-smooth tongue sole, and their expression in immune tissues is significantly changed after V. anguillarum infection, generally showing an inverse trend. We confirmed that CsC6 was the target gene of Cse-miR-727 using the dual luciferase reporter assay and that Cse-miR-727 regulated CsC6 at the protein level using quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. The hepatic expression levels of not only the MAC components C7, C8α, C8β, C8γ and C9 but also the MAPKs, NF-κβ, AP-1, IL1β, IL6 and TNFα, which are involved in many signaling pathways, changed significantly in half-smooth tongue sole following stimulation with the Cse-miR-727 agomir and inhibitor. This evidence suggested that CsC6 could be mediated by Cse-miR-727 to affect MAC assembly and immune signaling pathways in half-smooth tongue soles. To our best knowledge, this study is the first to investigate the regulatory mechanism and immune response of complement genes mediated by miRNAs in fish.

Proteomic analysis of differentially expressed whey proteins in Guanzhong goat milk and Holstein cow milk by iTRAQ coupled with liquid chromatography-tandem mass spectrometry

Guanzhong goat and Holstein cow milk are the major milks supplied in China. Whey proteins play an important role in immune defense for newborn mammals. This study aimed to analyze the differentially expressed whey proteins of Guanzhong goat milk and Holstein cow milk by using isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics techniques. A total of 165 whey proteins were quantified, 114 of which differed significantly in abundance in goat and cow milks. According to the "up_keywords," in the online DAVID tool (https://david.ncifcrf.gov/home.jsp), 75% of these differentially expressed whey proteins were related to the category of "signal." Gene Ontology analyses classified these differentially expressed proteins into biological processes, cellular components, and molecular functions. The most common biological process was response to stress, the most common cellular component was related to extracellular region, and the most prevalent molecular function was binding. Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that these proteins were mainly involved in the complement and coagulation cascade pathways. The results improve our understanding of the different biological properties of whey proteins in goat and cow milks.

Effect of a Small Selective Inhibitor of C-Jun N-Terminal Kinase on the Inducible mRNA Expression of Interleukin-6 and Interleukin-18

BACKGROUND:

The expression of many inducible genes, involved in cell growth and differentiation as cytokine genes are regulated by receptor-activated intracellular signalling pathways, including the c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase pathway.

AIM:

We examined the involvement of the JNK signalling pathway in the regulation of the inducible interleukin-6 (IL-6) and interleukin-18 (IL-18) gene expression at the transcriptional level.

METHODS:

Peripheral blood mononuclear cells (PBMC) from healthy donors were stimulated with lipopolysaccharide (LPS) and C3 binding glycoprotein (C3bgp) with or without SP600125 and cultured for 6 h. After mRNA isolation, a qRT-PCR was performed.

RESULTS:

Regarding IL-6 and IL-18 mRNA expression, donors were divided into two groups of high and low responders. SP600125 inhibited significantly IL-6 mRNA transcription in the high responder group and did not influence the transcription level in the low responder group. Concerning IL-18 mRNA, we detect the significant effect of SP600125 on the inducible mRNA in high responder group upon C3bgp stimulation.

CONCLUSION:

JNK transduction pathway is involved in the production of IL-6 mRNA, after LPS and C3bgp stimulation. We suggest that the inhibition of JNK may be beneficial only for higher responding patients during the treatment of inflammatory and autoimmune diseases.

Effect of a Histone Deacetylases Inhibitor of IL-18 and TNF-Alpha Secretion in Vitro

BACKGROUND:

Interleukin-18 (IL-18) and Tumor Necrosis Factor-alpha (TNF-α) are proinflammatory cytokines that increased the development of Th1 immune response, but have a different type of regulation of the gene expression. Whereas TNF-α has an inducible expression, IL-18 is translated as an inactive protein and required proteolytic cleavage by Casp-1 in inflammasome complexes.

AIM:

To investigate the effect of the histone deacetylases inhibitor Suberoylanilide Hydroxamic Acid (SAHA) on the gene expression and secretion of both cytokines, IL-18 and TNF-α, according to their contribution to the cancer development and anticancer immunity.

METHODS:

Isolated peripheral blood mononuclear cells (PBMC) were stimulated with LPS and C3bgp with or without SAHA. Cytokine production was assessed by ELISA at 6 and 24h.

RESULTS:

IL-18 and TNF-α secretion was significantly increased at 6h and 24h in response to stimulation. TNF-α production from stimulated PBMC was downregulated by SAHA at 6 and 24h. Treatment with SAHA does not inhibit the secretion of IL-18 significantly either at 6 or 24h of stimulation.

CONCLUSION:

The inhibition of histone deacetylases by SAHA does not influence the inflammasome-dependent production of immunologically active IL-18. In contrast, the production of proinflammatory TNF-α in cultures was mediated by the activity of HDAC class I and class II enzymes.

Epigenetic imprinting by commensal probiotics inhibits the IL-23/IL-17 axis in an in vitro model of the intestinal mucosal immune system

The pathophysiology of IBD is characterized by a complex interaction between genes and the environment. Genetic and environmental differences are attributed to the heterogeneity of the disease pathway and to the epigenetic modifications that lead to altered gene expression in the diseased tissues. The epigenetic machinery consists of short interfering RNA, histone modifications, and DNA methylation. We evaluated the effects of Bifidobacterium breve (DSMZ 20213) and LGG (ATCC 53103), as representatives of commensal probiotics on the expression of IL-17 and IL-23, which play an important role in IBD, and on the epigenetic machinery in a 3D coculture model composed of human intestinal HT-29/B6 or T84 cells and PBMCs. The cells were treated with LPS in the presence or absence of bacteria for 48 h, and the expression of IL-17, IL-23, and CD40 at the mRNA and protein levels was assessed using TaqMan qRT-PCR and ELISA, respectively. Western blotting was used to assess the expression of the MyD88, the degradation of IRAK-1 and IκBα, the expression of the NF-κB p50/p65 subunits, the p-p38 MAPK and p-MEK1, as well as histone modifications. NF-κB activity was assessed by NF-κB-dependent luciferase reporter gene assays. The accumulation of Ac-H4 and DNA methylation was quantitatively assessed using colorimetric assays. B. breve and LGG diminished the LPS-induced expression of IL-17, IL-23, CD40, and histone acetylation, while slightly enhancing DNA methylation. These effects were paralleled by a decrease in the nuclear translocation of NF-κB, as demonstrated by a decrease in the expression of MyD88, degradation of IRAK-1 and IκBα expression of the nuclear NF-κB p50/p65 subunits, p-p38 MAPK and p-MEK1, and NF-κB-dependent luciferase reporter gene activity in LPS-stimulated cells. B. breve and LGG may exert their anti-inflammatory effects in the gut by down-regulating the expression of the IBD-causing factors (IL-23/IL-17/CD40) associated with epigenetic processes involving the inhibition of histone acetylation and the optimal enhancement of DNA methylation, reflected in the limited access of NF-κB to gene promoters and reduced NF-κB-mediated transcriptional activation. We describe a new regulatory mechanism in which commensal probiotics inhibit the NF-κB-mediated transcriptional activation of IBD-causing factors (IL-23/IL-17/CD40), thereby simultaneously reducing histone acetylation and enhancing DNA methylation.

The inhibition of JNK and p38 MAPKs downregulates IL-10 and differentially affects c-Jun gene expression in human monocytes

Interleukin-10 is the most important anti-inflammatory cytokine that controls the progress of the immune response. The molecular mechanisms driving the IL10 gene regulation are not well understood. To gain insight into this process we studied the IL-10 expression on mRNA and protein levels, together with c-Jun, FOXP3 and RelA transcription factors gene expression in human monocytes. We investigated also, the involvement of JNK and p38 transduction pathways in IL-10, c-Jun, FOXP3 and RelA gene expression. The quantity determination of IL-10 was performed by ELISA. qRT-PCR was performed for the detection of mRNA transcripts. The pharmacological inhibitors SP600125 and SB202190 were used to explore JNK and p38 MAPKs involvement in IL10, c-Jun, FOXP3 and RelA gene expression. The measurement of IL-10 mRNA synthesis, triggered by lipopolysaccharide (LPS) or C3 binding glycoprotein (C3bgp) showed that stimulation with both inducers led to similar high level of IL-10 mRNA synthesis, whereas C3bgp was the stronger inducer of IL-10 production than LPS. JNK and p38 inhibition significantly decreased IL-10 expression in stimulated cells. C3bgp and LPS induced comparatively low expression of FOXP3, RelA and c-Jun mRNA in monocytes. The inhibition of p38 MAPK in stimulated monocytes resulted in significant enhancement of c-Jun mRNA synthesis suggesting the functional relation between p38 MAPK and c-Jun gene expression. We concluded that the IL10 gene transcription did not associate with enhancement of c-Jun, RelA and FOXP3 gene expression and strictly depended on the JNK and p38 MAPKs activation in stimulated human monocytes.

Differences in the inducible gene expression and protein production of IL-12p40, IL-12p70 and IL-23: involvement of p38 and JNK kinase pathways

The proper balance between IL-12p40-related cytokines controls the appearance of normal and pathological Th1 immune responses. In this study, we examined the inducible IL-12p40, IL-12p35 and IL-23p19 mRNA expression and protein production in human peripheral blood mononuclear cells (PBMC) and purified monocytes, isolated from healthy donors. We investigated how JNK and p38 MAPKs inhibitors influenced IL-12p40, IL-12p70 and IL-23 production. The cytokines' quantity determination was performed by ELISA. qRT-PCR was performed for mRNA transcripts detection. All stimuli tested induced higher level of IL-12p40 and IL-12p19 mRNAs. LPS was the strongest inducer of IL-12p40 mRNA, whereas C3bgp stimulated the highest expression of IL-23p19 mRNA in human monocytes. IL-12p40 and IL-23 protein production observed was increased in the highest level after C3bgp stimulation. The inhibition of both JNK and p38 augmented IL-12p40 production. The inhibition of p38 MAPK downregulated IL-23 production and upregulated IL-12p40 production in stimulated monocytes and PBMC. These results provide evidence that in human monocytes and PBMC p38 MAP kinase activation has an opposite effect on the IL-12p40 and IL-23 expression.