Altered frequency of IL-10+ B cells in apolipoprotein E deficient mice with established atherosclerosis
-
1
Universidad de Antioquia, Instituto de Investigaciones Médicas, Facultad de Medicina, Sede de Investigación Universitaria, Colombia
-
2
Universidad de Antioquia, Instituto de Investigaciones Médicas, Facultad de Medicina, Colombia
-
3
Universidad CES, Facultad de Medicina, Colombia
Introduction
Cardiovascular diseases (CVD) are one of the main worldwide leading causes of death. Atherosclerosis, considered the most common cause of CVD, is an inflammatory process characterized by lipid accumulation, infiltration of immune cells and fibro-fatty plaque formation in the intima of large and medium caliber arteries.
In atheroma conformation, there is a pathological involvement of innate immune cells such as macrophages, and cells of the adaptive immune system such as T lymphocytes. Meanwhile, B cells have been attributed both protective and proatherogenic roles, which apparently depends on the subpopulation involved and the previous antigenic contact. In the last decade, the existence of B cells with regulatory functions and their role in different chronic inflammatory diseases was described. The regulation exerted by these cells mainly depends on IL-10 production, which inhibits the secretion of cytokines such as TNF-alpha and IFN-γ and the proliferation of CD4+CD25- T cells. It was suggested that regulatory B cells (Breg) could belong to three different subsets: a) Innate (Marginal zone-MZ and CD5+ cells), which produce IL-10 rapidly in response to stimuli such as Toll-like receptors ligands, b) Immature (Transitional 2-T2) and c) adaptive (Follicular-FO), that express IL-10 after long (48-72 h) CD40 stimulation in the presence or absence of other stimuli.
The role of IL-10+ B cells in the immunopathology of atherosclerosis is currently unknown. Hence, we evaluated the frequency and phenotype of subpopulations of IL-10+ B cells in spleen from apoE-/- mice with established atherosclerosis and control mice by flow cytometry.
Materials and methods
Female apoE-/- mice of 8 weeks-old were fed with high fat diet (HFD) during 12 weeks (defined as mice with established atherosclerosis). Wild type mice fed with standard diet or HFD corresponded to control groups. B cells were classified into CD5+ and CD5- populations. The later was subsequently divided into immature Transitional 1 like (T1-like) and T2, and mature MZ and FO cells, according to CD21 and CD23 expression.
The evaluation of the B cell subsets that produce IL-10 was performed by flow cytometry after two types of stimulation: Ex vivo for 5 h with lipopolysaccharide, phorbol 12-myristate 13-acetate (PMA) plus ionomycin, in the presence of monensin and brefeldin (L+PIMB). In vitro culture for 72 h with an antibody against CD40 and re-stimulation with L+PIMB during the last 5 h.
Results
An increase in the frequency of IL-10+ B cells was observed after ex vivo and in vitro cultures of splenocytes from mice with established atherosclerosis. IL-10+ B cells had high expression of CD19, CD1d and IgM, but variable of CD5, CD21 and CD23. In the ex vivo cultures, a reduction in the frequency of IL-10+ CD5+ and IL-10+ MZ subpopulations (innate regulatory B cells) and increased IL-10+ FO and IL-10+ T1-like B cells were observed in mice with established atherosclerosis.
In vitro, a lower frequency of IL-10+ T2 and IL-10+ FO B cell subsets (immature and adaptive regulatory B cells, respectively) and a higher frequency of IL-10+ MZ and IL-10+ like T1 B cells was observed in mice with established atherosclerosis. A positive correlation between cholesterol levels and frequency of splenic IL-10+ B cells (CD5+ and like T1 B cell phenotype) was found after ex vivo cultures.
Conclusion
These results suggest that atherosclerotic mice have a lower proportion of IL-10 producing innate, immature and adaptive B cell subpopulations, which probably contribute with the chronic inflammatory process present in atherosclerosis.
Acknowledgements
This work received financial support by the grants (Colciencias project number 111554431390) and Programa de Sostenibilidad Universidad de Antioquia 2014-2015
Keywords:
IL-10,
B cell,
Atherosclerosis,
Apolipoproteins E,
Breg
Conference:
IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología, Medellin, Colombia, 13 Oct - 16 Oct, 2015.
Presentation Type:
Poster Presentation
Topic:
Adaptive Immunity
Citation:
Rincón-Arévalo
H,
Castano
DM,
Villa-Pulgarín
J,
Ramírez-Pineda
JR,
Vásquez
GM and
Yassin
L
(2015). Altered frequency of IL-10+ B cells in apolipoprotein E deficient mice with established atherosclerosis.
Front. Immunol.
Conference Abstract:
IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología.
doi: 10.3389/conf.fimmu.2015.05.00047
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
24 Apr 2015;
Published Online:
14 Sep 2015.
*
Correspondence:
Dr. Diana M Castano, Universidad de Antioquia, Instituto de Investigaciones Médicas, Facultad de Medicina, Sede de Investigación Universitaria, Medellin, Colombia, dmcastano@gmail.com
Dr. Lina Yassin, Universidad CES, Facultad de Medicina, Medellin, Colombia, yascatorce@yahoo.com