Peripheral Blood Cytokine Levels After Acute Myocardial Infarction: IL-1β- and IL-6-Related Impairment of Bone Marrow Function

Abstract

Rationale: Intracoronary infusion of bone marrow (BM) mononuclear cells after acute myocardial infarction (AMI) has led to limited improvement in left ventricular function. Although experimental AMI models have implicated cytokine-related impairment of progenitor cell function, this response has not been investigated in humans.

Objective: To test the hypothesis that peripheral blood (PB) cytokines predict BM endothelial progenitor cell colony outgrowth and cardiac function after AMI.

Methods and results: BM and PB samples were collected from 87 participants 14 to 21 days after AMI and BM from healthy donors was used as a reference. Correlations between cytokine concentrations and cell phenotypes, cell functions, and post-AMI cardiac function were determined. PB interleukin-6 (IL-6) negatively correlated with endothelial colony-forming cell colony maximum in the BM of patients with AMI (estimate±SE, -0.13±0.05; P=0.007). BM from healthy individuals showed a dose-dependent decrease in endothelial colony-forming cell colony outgrowth in the presence of exogenous IL-1β or IL-6 (P<0.05). Blocking the IL-1R or IL-6R reversed cytokine impairment. In AMI study participants, the angiogenic cytokine platelet-derived growth factor BB glycoprotein correlated positively with BM-derived colony-forming unit-endothelial colony maximum (estimate±SE, 0.01±0.002; P<0.001), multipotent mesenchymal stromal cell colony maximum (estimate±SE, 0.01±0.002; P=0.002) in BM, and mesenchymal stromal cell colony maximum in PB (estimate±SE, 0.02±0.005; P<0.001).

Conclusions: Two weeks after AMI, increased PB platelet-derived growth factor BB glycoprotein was associated with increased BM function, whereas increased IL-6 was associated with BM impairment. Validation studies confirmed inflammatory cytokine impairment of BM that could be reversed by blocking IL-1R or IL-6R. Together, these studies suggest that blocking IL-1 or IL-6 receptors may improve the regenerative capacity of BM cells after AMI.

Clinical trial registrations: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00684060.

Keywords: bone marrow cells; cell therapy; interleukin-1; interleukin-6; myocardial infarction.

Conflict of interest statement

DISCLOSURES

The authors have no disclosures of conflict of interest. Dr. Joshua Hare reports equity ownership and board membership in Vestion. Vestion did not fund or participate in this research. The opinions expressed by one of the authors (RFE) do not necessarily reflect those of the National Institutes of Health, the National Heart, Lung, and Blood Institute, or the US Department of Health and Human Services.

© 2017 American Heart Association, Inc.

Figures

Figure 1. Differences in Cardiac Functional Parameters (Measured by cardiac MRI) at baseline and 6 month follow-up Versus Peripheral Blood Concentrations of Interleukin 6 and Interleukin 10

The differences of cardiac MRI (A) ejection fraction (EF), (B) left ventricular end systolic volume (LVESV) and (C) left ventricular end diastolic volume (LVEDV) at baseline immediately prior to cell therapy and six months follow up are plotted according to peripheral blood IL-6 and IL-10 levels. Participants with high IL-6 and IL-10 concentration in PB (IL-6 hi IL-10 hi ) showed significantly lower LVEF changes at 6 months follow up (-3.41 ± 5.3 vs. 13.84 ± 7.8, P=0.01). Moreover study participants with IL-6 hi IL-10 hi showed an increase in LVESV (+14.6 mL ± 25.3 mL) at 6 months follow up compared with those with IL-6 hi IL-10 lo (-52.4 mL ± 63.19 mL, P=0.03). (* P<0.05).

Figure 2. IL-6 Receptor Antagonist Improved Bone Marrow-Derived Vasculogenic Colony Outgrowth * P-value

(A) A representative phase-contrast micrograph of an ECFC colony without IL-6 treatment. (B) A representative phase-contrast micrograph of an ECFC colony after IL-6 treatment. (C) BM mononuclear cells from three healthy individuals were treated with increasing concentrations of IL-6. The cells were cultured in ECFC assays and colony numbers were enumerated every other day for 14 days. IL-6 produced a dose-dependent impairment of BM endovascular colony outgrowth. ECFC colony count maximum was decreased after exposure to 1 μg/mL of IL-6 (mean±SD: 7.42±2.31, P=0.01), 10 μg/mL of IL-6 (mean±SD: 5.71±2.41, P=0.002) and 100 μg/mL of IL-6 (mean±SD: 2.28±1.11, P=0.001) vs. healthy control group (mean±SD: 11.42 ±4.43). (D) Colony numbers of the BM-MNCs, treated with 1 μg/mL of IL-6 in ECFC assays, were compared with ECFC colony counts after adding 1 μg/mL IL-6Ra. ECFC colony count maximum significantly increased after exposure to IL-6Ra (mean±SD: 7±3.64, P=0.003) vs. control group (mean±SD: 5.8 ±3.34). IL-6Ra improved BM-derived vasculogenic capacity.

Figure 3. Interleukin-1 receptor antagonist (IL-1Ra) improved endothelial colony forming cells (ECFC) outgrowth (* P

Healthy BM-MNCs were cultured in ECFC assay in presence of increasing concentrations of (A) IL-1α and (B) IL-1β (1, 10, or 100 μg/mL). Colony formations enumerated for 2 weeks, and the maximal number of colonies per plate was used for analyses. EFCF colony counts significantly decreased after exposure to IL-1α or IL-1β in a dose-dependent manner. Colony numbers of Healthy BM-MNCs treated with 1μg/mL IL-1α (C) or 1μg/mL IL-1β (D) as a control group, were compared with ECFC colony counts after exposing to increasing concentrations of IL-1Ra (0.1, 0.5, 1ng/mL). EFCF colony outgrowth improved significantly after treating with IL-1Ra