title: Plaque Size Is Decreased but M1 Macrophage Polarization and Rupture Related Metalloproteinase Expression Are Maintained after Deleting T-Bet in ApoE Null Mice.
abstract: BACKGROUND
  Thelper1 (Th1) lymphocytes have been previously implicated in atherosclerotic plaque growth but their role in plaque vulnerability to rupture is less clear. We investigated whether T-bet knockout that prevents Th1 lymphocyte differentiation modulates classical (M1) macrophage activation or production of matrix degrading metalloproteinases (MMPs) and their tissue inhibitors, TIMPs.
  
  
  RESULTS
  We studied the effect of T-bet deletion in apolipoproteinE (ApoE) knockout mice fed a high fat diet (HFD) or normal chow diet (ND). Transcript levels of M1/M2 macrophage polarization markers, selected MMPs and TIMPs were measured by RT-qPCR in macrophages isolated from subcutaneous granulomas or in whole aortae. Immunohistochemistry of aortic sinus (AS) and brachiocephalic artery (BCA) plaques was conducted to quantify protein expression of the same factors. Deletion of T-bet decreased mRNA for the M1 marker NOS-2 in granuloma macrophages but levels of M2 markers (CD206, arginase-1 and Ym-1), MMPs-2, -9, -12, -13, -14 and -19 or TIMPs-1 to -3 were unchanged. No mRNA differences were observed in aortic extracts from mice fed a HFD for 12 weeks. Moreover, AS and BCA plaques were similarly sized between genotypes, and had similar areas stained for NOS-2, COX-2, MMP-12 and MMP-14 proteins. T-bet deletion increased MMP-13, MMP-14 and arginase-1 in AS plaques. After 35 weeks of ND, T-bet deletion reduced the size of AS and BCA plaques but there were no differences in the percentage areas stained for M1 or M2 markers, MMPs-12, -13, -14, or TIMP-3.
  
  
  CONCLUSIONS
  Absence of Th1 lymphocytes is associated with reduced plaque size in ApoE knockout mice fed a normal but not high fat diet. In either case, M1 macrophage polarization and expression of several MMPs related to plaque instability are either maintained or increased.
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Tsaousi
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Hayes
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Karina
authors.initials: K
authors.lastname: Di Gregoli
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Bond
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Laura
authors.initials: L
authors.lastname: Bevan
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Anita C
authors.initials: AC
authors.lastname: Thomas
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Newby
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000378:metabolism; D001011:Aorta / Q000473:pathology; D001057:Apolipoproteins E / Q000172:deficiency* / Q000378:metabolism; D001202:Ascitic Fluid / Q000166:cytology; D016764:Cell Polarity / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism; D059305:Diet, High-Fat; D005434:Flow Cytometry; D017353:Gene Deletion; D006099:Granuloma / Q000473:pathology; D007150:Immunohistochemistry; D008055:Lipids / Q000097:blood; D008262:Macrophage Activation / Q000187:drug effects; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010641:Phenotype; D058226:Plaque, Atherosclerotic / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013154:Spleen / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000172:deficiency*; D019714:Tissue Inhibitor of Metalloproteinases / Q000235:genetics / Q000378:metabolism; D000098815:T-bet Transcription Factor
chemical_list: D000950:Antigens, Ly; D001057:Apolipoproteins E; D016207:Cytokines; D008055:Lipids; C494192:Ly-6C antigen, mouse; D012333:RNA, Messenger; D020825:T-Box Domain Proteins; D000098815:T-bet Transcription Factor; D019714:Tissue Inhibitor of Metalloproteinases; D016173:Macrophage Colony-Stimulating Factor; D020782:Matrix Metalloproteinases