title: Early matrix metalloproteinase-9 inhibition post-myocardial infarction worsens cardiac dysfunction by delaying inflammation resolution.
abstract: Matrix metalloproteinase-9 (MMP-9) is robustly elevated in the first week post-myocardial infarction (MI). Targeted deletion of the MMP-9 gene attenuates cardiac remodeling post-MI by reducing macrophage infiltration and collagen accumulation through increased apoptosis and reduced inflammation. In this study, we used a translational experimental design to determine whether selective MMP-9 inhibition early post-MI would be an effective therapeutic strategy in mice. We enrolled male C57BL/6J mice (3-6months old, n=116) for this study. Mice were subjected to coronary artery ligation. Saline or MMP-9 inhibitor (MMP-9i; 0.03μg/day) treatment was initiated at 3h post-MI and the mice were sacrificed at day (D) 1 or 7 post-MI. MMP-9i reduced MMP-9 activity by 31±1% at D1 post-MI (p<0.05 vs saline) and did not affect survival or infarct area. Surprisingly, MMP-9i treatment increased infarct wall thinning and worsened cardiac function at D7 post-MI. While MMP-9i enhanced neutrophil infiltration at D1 and macrophage infiltration at D7 post-MI, CD36 levels were lower in MMP-9i compared to saline, signifying reduced phagocytic potential per macrophage. Escalation and prolongation of the inflammatory response at D7 post-MI in the MMP-9i group was evident by increased expression of 18 pro-inflammatory cytokines (all p<0.05). MMP-9i reduced cleaved caspase 3 levels at D7 post-MI, consistent with reduced apoptosis and defective inflammation resolution. Because MMP-9i effects on inflammatory cells were significantly different from previously observed MMP-9 null mechanisms, we evaluated pre-MI (baseline) systemic differences between C57BL/6J and MMP-9 null plasma. By mass spectrometry, 34 plasma proteins were significantly different between groups, revealing a previously unappreciated altered baseline environment pre-MI when MMP-9 was deleted. In conclusion, early MMP-9 inhibition delayed inflammation resolution and exacerbated cardiac dysfunction, highlighting the importance of using translational approaches in mice.
authors.affiliation: San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.
authors.forename: Rugmani Padmanabhan
authors.initials: RP
authors.lastname: Iyer
authors.affiliation: San Antonio Cardiovascular Proteomics Center, USA; Brody School of Medicine, Department of Physiology, East Carolina University, Greenville, NC, USA.
authors.forename: Lisandra E
authors.initials: LE
authors.lastname: de Castro Brás
authors.affiliation: San Antonio Cardiovascular Proteomics Center, USA.
authors.forename: Nicolle L
authors.initials: NL
authors.lastname: Patterson
authors.affiliation: Millipore Sigma (A business of Merck KGaA, Darmstadt, Germany), Natick, MA, USA.
authors.forename: Manishabrata
authors.initials: M
authors.lastname: Bhowmick
authors.affiliation: San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Flynn
authors.affiliation: Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.
authors.forename: Majdouline
authors.initials: M
authors.lastname: Asher
authors.affiliation: San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.
authors.forename: Presley L
authors.initials: PL
authors.lastname: Cannon
authors.affiliation: San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.
authors.forename: Kristine Y
authors.initials: KY
authors.lastname: Deleon-Pennell
authors.affiliation: San Antonio Cardiovascular Proteomics Center, USA; Florida Atlantic University, Boca Raton, FL, USA.
authors.forename: Gregg B
authors.initials: GB
authors.lastname: Fields
authors.affiliation: San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA; Research Service, G.V. (Sonny) Montgomery Veterans Affairs Medical Center, Jackson, MS, USA. Electronic address: mllindsey@umc.edu.
authors.forename: Merry L
authors.initials: ML
authors.lastname: Lindsey
mesh_terms: D000818:Animals; D017209:Apoptosis; D015415:Biomarkers; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D004789:Enzyme Activation; D005109:Extracellular Matrix / Q000378:metabolism; D015870:Gene Expression; D007150:Immunohistochemistry; D007249:Inflammation / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D018836:Inflammation Mediators / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009026:Mortality; D009203:Myocardial Infarction / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D020556:Neutrophil Infiltration; D034622:RNA Interference; D018754:Ventricular Dysfunction / Q000235:genetics / Q000378:metabolism*; D018487:Ventricular Dysfunction, Left / Q000235:genetics / Q000378:metabolism / Q000473:pathology
chemical_list: D015415:Biomarkers; D016207:Cytokines; D018836:Inflammation Mediators; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9
keywords: Apoptosis; Inhibitor; MMP-9; Macrophage; Myocardial infarction; Neutrophil; Proteomics