Relevance of lymphocytes in collateral artery growth (arteriogenesis)

Konda, Kumaraswami (2022): Relevance of lymphocytes in collateral artery growth (arteriogenesis). Dissertation, LMU München: Medizinische Fakultät

Abstract

Arteriogensis is a natural bypass growth of preexisting arteriole to fully functioning arteries that rescue organs from ischemic damage and necrosis. Neutrophil extravasation and mast cell degranulation are the early cellular events in this process. The Role of B cells in arteriogenesis has never been studied. There is contradictory evidence of CD4+ and CD8+ T cells role in arteriogenesis. My study aims to identify the role of lymphocytes in arteriogenesis. Using Rag1 KO mice, I found lack of B and T cells Rag1 KO mice showed impaired arteriogenesis. Macrophage phenotype analysis in perivascular space revealed that impaired arteriogenic response in Rag1 KO mice was associated with increased number of inflammatory (CD68+MRC1-) macrophages and reduced number of regenerative (CD68+MRC1+) macrophages indicating the role of adaptive immune system in resolving the inflammation and facilitate the collateral artery growth. Next, in WT mice, CD20 mediated B cell depletion resulted in impaired arteriogenesis associated with the reduced regenerative macrophage accumulation. Not only B cells, but fraction of CD20+ T cells and eosinophils were also depleted by CD20 depletion. Flow cytometry analysis showed that CD20 expression was not limited to B cells but also other cell types, i.e., CD4 T cells, CD8 T cells, γδ T cells, and eosinophils. Imaging cytometry using two clones of CD20 antibodies confirms this observation and explains why CD20 depletion affected CD4 T cells, γδ T cells, and eosinophils. These results draw a tentative conclusion on the role of B cells in arteriogenesis. B cell-deficient (JHT KO) mice provide a better alternative to study the role of B cells in arteriogenesis. B cell-deficient mice showed reduced arteriogenesis; however, inflammatory (CD68+MRC1-) and regenerative (CD68+MRC1+) macrophage accumulation were not affected by B cells absence. Histology immunofluorescence analysis showed the presence of CD20+ cells in B cell-deficient mice, and these cells might be the reason why B cell-deficient mice have similar macrophages compared to WT mice. CD20 depletion in B cell-deficient mice showed a strong negative effect on arteriogenesis, associated with an increased number of inflammatory (CD68+MRC1-) macrophages and decreased regenerative (CD68+MRC1+) macrophages. Next, analysis from TCRα KO mice showed me that lack of CD4 and CD8 T cells does not impact arteriogenesis and favored regenerative (CD68+MRC1+) macrophage accumulation. Nevertheless, surprisingly, γδ T cell depletion negatively affected arteriogenesis in TCRα KO mice and WT mice. Furthermore, γδ T cell depletion also reduced the regenerative (CD68+MRC1+) macrophage accumulation. My study, for the first time, identified the involvement of γδ T cell in arteriogenesis. γδ T cells expressing IFN-γ in arteriogenesis. Macrophage activation status analysis showed that CD169 (Siglec-1) expression decreased in γδ T cell depleted mice. CD169 macrophages showed vascular growth-promoting properties as analyzed by expression of IL-10 and PDGFβ. In conclusion, my study provides convincing evidence of the contribution of B cells and γδ T cells in collateral artery growth (arteriogenesis).

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften ; 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• Fakultäten: Medizinische Fakultät
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 27. Juli 2022
• 1. Bericht­erstatter:in: Deindl, Elisabeth