Regulation of Allergic Immune Responses by Microbial Metabolites

Emerging evidence demonstrates that the microbiota plays an essential role in shaping the development and function of host immune responses. A variety of environmental stimuli, including foods and commensals, are recognized by the host through the epithelium, acting as a physical barrier. Two allergic diseases, atopic dermatitis and food allergy, are closely linked to the microbiota, because inflammatory responses occur on the epidermal border. The microbiota generates metabolites such as short-chain fatty acids and poly-γ-glutamic acid (γPGA), which can modulate host immune responses. Here, we review how microbial metabolites can regulate allergic immune responses. Furthermore, we focus on the effect of γPGA on allergic T helper (Th) 2 responses and its therapeutic application.

Mecanismos de activación de las células T asesinas naturales invariantes (iNKT) / Mecanismos de ativação das células T assassinas naturais invariantes (iNKT) / Activation mechanisms of invariant natural killer T cells (iNKTs)

Aunque se ha logrado un conocimiento amplio acerca de las células T asesinas naturales (iNKT), aún no existe consenso sobre sus mecanismos de activación. Dichas células reconocen diferentes antígenos glicolipídicos presentados por medio de la molécula CD1d, los cuales pueden ser endógenos, exógenos derivados de organismos como bacterias y sintéticos desarrollados para aplicaciones clínicas. Existe mucho interés en entender cómo estas distintas variantes glicolipídicas inducen diferentes tipos de polarización, pero ha sido muy difícil llegar a un consenso, debido a que la respuesta depende de varios factores como la naturaleza, la internalización y el procesamiento de los glicolípidos. Además, la activación de las células iNKT la determinan el tipo y estado de activación de la célula presentadora de antígeno, las moléculas coestimuladoras, los mecanismos de transactivación y la localización de los complejos CD1d-glicolípido en distintas microrregiones de la membrana plasmática, como las balsas lipídicas. Esta revisión explora la evidencia sobre los factores que afectan la activación de las células iNKT con el fin de entender su potencial inmunomodulador.

A great amount of knowledge on natural killer T cells (iNKTs) is now available, but a consensus about their activation mechanisms has not been reached. These cells recognize different glycolipid antigens through the CD1d molecule. Such antigens may be endogenous, derived from bacteria (foreign) and synthetic, the latter have been developed for clinical applications. There exists much interest in understanding how these different glycolipid compounds induce different types of polarization, but it has been difficult to reach a consensus due to the fact that responses depend on different factors such as: the nature of the molecule, the internalization process and the presentation of the glycolipids. Moreover, activation of iNKT cells is determined by the type and state of the antigen presenting cell, the co-stimulatory molecules, the transactivation mechanisms and the location of the glycolipid-CD1d complexes on the plasma membrane, such as the lipid rafts. This review explores the evidence about the factors that affect activation of iNKT cells in order to understand their immune-modulatory potential.

Ainda que se conseguiu um conhecimento amplo a respeito das células T assassinas naturais (iNKT), ainda não existe consenso sobre seus mecanismos de ativação. Ditas células reconhecem diferentes antígenos glicolipídicos apresentados por meio da molécula CD1d, os quais pode ser: endógenos, exógenos derivados de organismos como bactérias e sintéticos desenvolvidos para aplicações clínicas. Existe muito interesse em entender como estas diferentes variantes glicolipídicas induzem diferentes tipos de polarização, mas foi muito difícil chegar a um consenso, devido a que a resposta depende de vários fatores como a natureza, a internalização e o processamento dos glicolípidos. Ademais, a ativação das células iNKT a determinam o tipo e estado de ativação da célula apresentadora de antígeno, as moléculas co-estimuladoras, os mecanismos de transativação e a localização dos complexos CD1d-glicolípido em diferentes microrregiões da membrana plasmática, como as balsas lipídicas. Esta revisão explora a evidência sobre os fatores que afetam a ativação das células iNKT com o fim de entender seu potencial imunomodulador.

Effects of immunostimulator CH2 b on mixed peptides derived from glucose-6-phosphate isomerase induces arthritis / 中国免疫学杂志

Objective:To explore the effect of the synthetic immunomodulator CH 2b with a thiazolidin-4-one ring on the pathogenesis of rheumatoid arthritis (RA) mice induced by glucose-6-phosphate isomerase(GPI) mixed peptides.Methods:hGPI325-339 ,hGPI469-483 peptide fragments were mixed with complete freund′s adjuvant fully ,DBA/1 mice were givien subcutaneous injection of the emulsifiers,pertussis toxin to strengthen immunity.And then RA mice were intervened with α-GalCer and CH2b,the changes of body weight ,ankle joint symptoms scores were observed .The joint tissues stained with hematoxylin and eosin ( HE) was used to evaluate the inflammatory cells.Fluorescence-activated cell sorting ( FACS) was used to detect the frequency changes of iNKT cells .Cytometric bead array(CBA) was used to analyze the levels of serum cytokines TNF-α,IL-6,IL-4,IFN-γ.Results: Compared with the model group,α-GalCer,CH2b could reduce the inflammation of the model mice ,significantly improve the body weight growth and the joint swelling(P0.05).Conclusion:Immunomodulator CH2b by activating iNKT cells affect the secretion of inflammatory cytokines ,and it relieved the GPI induced arthritis .

Immunization with mixed peptides derived from glucose-6-phosphate isomerase induces rheumatoid arthritis in DBA/1 mice / 中国病理生理杂志

[ ABSTRACT] AIM:To establish an animal model of rheumatoid arthritis ( RA) in DBA/1 mice induced by im-munodominant mixed peptides derived from glucose-6-phosphate isomerase (GPI).METHODS: The DBA/1 mice were immunized with emulsified mixed peptide fragments of hGPI 325-339+hGPI469-483 or single peptide hGPI325-339 in com-plete Freund′s adjuvant by subcutaneous injection to induce the model of RA .Body weight , ankle joint symptom scores , the pathological change of the ankle joint , the levels of CD4 +T cells in the spleen and peripheral blood , the proportion of iNKT cells in the peripheral blood , and the levels of TNF-αand IL-6 in serum were detected to evaluate and analyze the model.RESULTS:The hind paw of the model mice appeared red swelling on the 8th day, and then aggravated gradually to the limbs.The red swelling reached peak on the 14th day, and then relieved gradually .Inflammation response dominated by lymphocytes and monocytes was observed in the ankle joint .The inflammatory effect of mixed peptides was more obvious than that of the single one (P<0.05).Compared with control group and the mice treated with single peptide , the weight gain was slow, the amount of CD4 +T cells in the peripheral blood and spleen were increased , the proportion of peripheral iNKT cells in the inflammatory peak was decreased (P<0.05), and the serum level of TNF-αwas increased significantly ( P<0.05) in the mice treated with mixed peptide fragments .CONCLUSION: The immunological characteristics of RA model induced by mixed GPI peptides in DBA/1 mice is closer to that in RA patients , especially in the immunopathology of iNKT cells.Therefore, this model can be used as a new tool for studying the mechanism and immunological intervention of RA.

Study of the correlation between the percentage of iNKT cells and the ratio of IFN-γ/IL-4 in patients with rheumatoid arthritis / 中华微生物学和免疫学杂志

Objective To investigate the alterations of invariant nature killer T( iNKT) cells in peripheral blood samples from patients with rheumatoid arthritis ( RA) and to clarify the correlation between the percentage of iNKT cells and the ratio of IFN-γ/IL-4 in order to further understand the significance of iNKT cells in the development of RA.Methods Peripheral blood mononuclear cells ( PBMCs) were isola-ted from 70 patients with RA and 40 healthy subjects.Among them, thirty patients in the stage of inactive RA were involved in a follow-up study.Fluorescence activated cell sorting ( FACS) was used to detect the percentage of iNKT cells.PBMCs were cultured in vitro for analysis of cytokine production.The dynamic changes of iNKT cells in percentages were analyzed by FACS.MILLIPLEX MAP Human Cytokine/Chemo-kine kit was used to measure the secretion of IFN-γand IL-4 in serum samples and culture media of PBMCs. The expression of IFN-γand IL-4 in iNKT cells at mRNA level were analyzed by RT-PCR.Results Com-pared with the healthy subjects, the patients with active RA showed the delayed proliferation of iNKT cells and the decreased percentages and proliferation rates of iNKT cells (P0.05).The ratios of IFN-γ/IL-4 in serum samples and culture media of PBMCs were increased in patients with active RA as compared with those in patients with inactive RA and healthy subjects (P0.05).Compared with healthy subjects and patients with inactive RA, patients with active RA showed increased transcriptional level of IFN-γand decreased transcriptional level of IL-4.No significant differences with the expression of IFN-γand IL-4 in iNKT cells at mRNA level were observed between healthy subjects and patients with inactive RA.The per-centage of iNKT cells was negatively related to the IFN-γ/IL-4 ratio in patients with RA (P<0.05).Con-clusion Decreased percentage and impaired function of iNKT cells were detected in patients with RA. iNKT cells were closely related to the development and disease activity of RA.

Alpha-galactosylceramide loaded tumor cells in combination with TLR9 agonists induce potent anti-tumor responses in a murine model of colon cancer / 中华微生物学和免疫学杂志

Objective To design a new cancer vaccine by using alpha-galactosylceramide (α-Galcer,α-GC) loaded tumor cells in combination with TLR 9 ligand and to evaluate its therapeutic effects on colon canc-er in mice.Methods MC38 cells were transfected with lentivirus (GFP-CD1d) to prepare CD1d-MC38 cells. The expression of CD1d molecules in CD1d-MC38 cells was detected by fluorescence microscopy , RT-PCR and flow cytometry.The sorted CD1d-MC38 cells were loaded with α-Galcer to prepare CD1d-MC38/α-GC complex. Flow cytometry was performed to evaluate the efficiency of combination .A mouse model of colon cancer was es-tablished to investigate the therapeutic effects of α-Galcer loaded tumor cells in combination with TLR 9 ligand ( CD1d-MC38/α-GC+CpG1826) on colon cancer in mice by analyzing tumor growth and mice survival time .Im-munohistochemical staining was used to detect CD 4+T and CD8+T infiltrating lymphocytes in tumor tissues .Re-sults The MC38 cancer cells that expressed CD 1d and GFP were successfully constructed , among which 98.10%±2.53%were positive for CD1d.Moreover, the CD1d-MC38 cells could combine with α-Galcer effec-tively in a dose and time dependent manner .Compared with PBS treated group ,α-GC treated group and TLR9 ligand treated group , the experimental vaccine strategy was sufficient to inhibit the growth of established tumors and prolong survival of tumor-bearing mice (P<0.01).Immunohistochemistry analysis revealed that levels of CD4+T cells and CD8+T cells in experiment group were significantly higher than those in groups treated with PBS,α-GC and TLR9 ligand (P<0.01).Conclusion CD1d-MC38/α-GC in combination with CpG1826 could efficiently inhibit the growth of established tumors and prolong survival of tumor-bearing mice .Immunohisto-chemistry analysis revealed that CD 4+T cells and CD8+T cells played important roles in anti-tumor immunity.

Papel de las células nkt invariantes en la respuesta inmune anti-viral: [revisión] / Role of invariant nkt cells in the anti-viral immune response: [review]

Las células T asesinas naturales con receptor de células T invariante y restringidas por la molécula CD1d (iNKT) son un subgrupo de linfocitos con potente actividad inmunorreguladora; su respuesta casi inmediata y la capacidad de producir citoquinas tanto Th1 como Th2 son factores determinantes en el desarrollo de la respuesta inmune innata y adaptativa. El papel fisiológico de las células iNKT se ha documentado ampliamente en la respuesta anti-tumoral, el desarrollo de la tolerancia en los órganos inmunoprivilegiados y el control de las reacciones autoinmunes. A pesar de la demostrada potencia inmunomoduladora de las células iNKT, hasta el momento se conoce poco de su acción en la respuesta inmune anti-infecciosa, en particular en el ser humano y contra los virus patógenos. Este artículo sintetiza los resultados de una búsqueda en las principales bases de datos biomédicas (Pubmed, Medline y OVID), e incluye los estudios realizados para caracterizar estas células y evaluar su papel en la interacción del hospedero con los virus. Las células iNKT participan en la respuesta inmune antiviral, aunque de una manera diferente según el tipo de virus; incluso, podrían estar comprometidas en los daños mediados por mecanismos inmunes. En el ser humano, las células iNKT son aparentemente esenciales en la respuesta inmune contra el virus Varicela Zoster, mientras que todavía hay controversia sobre su función en el control de otros virus. Los modelos animales han aportado las primeras evidencias sobre el potencial de la manipulación terapéutica específica de este subgrupo de linfocitos.

Natural killer T cells with an invariant T-cell receptor and restricted by CD1d (iNKT) are a subgroup of lymphocytes with a very strong immunoregulatory potential; their quick response and their ability to produce Th1 and Th2 cytokines are determinant factors that influence the development of innate and adaptive immune responses. The physiological role of iNKT cells has been well documented in anti-tumor immune responses, the development of tolerance in immune-privileged organs and the control of autoimmune diseases. Despite the fact that the immunoregulatory potential of these cells has been well documented, less is known regarding their role in the immune response against infectious agents, in particular to human pathogenic viruses. This paper synthesizes the search in the most important biomedical data bases (Pubmed, Medline, OVID), including studies on the phenotypic characterization of these cells and functional studies that evaluated their role in the interaction between hosts and viruses. iNKT cells have a heterogeneous participation during the anti-viral immune responses, depending on the type of virus; indeed, in some instances the iNKT-cell responses can be involved in the tissue damage associated to the anti-viral responses. In humans, iNKT cells are apparently essential for an effective immune response against Varicella Zoster virus, while it is still controversial their role in the control of other viral infections. Studies in animal models have shown the first evidences on the therapeutic potential of this lymphocyte subpopulation.