PubMed: 28400318

Title
Hemopexin counteracts systolic dysfunction induced by heme-driven oxidative stress.
Journal
Free radical biology & medicine
Volume
108
Issue
None
Pages
452-464
Date
2017-07-01
Authors
Vinchi F | Ingoglia G | Petrillo S | Tolosano E | Altruda F | Cimino J | De Franceschi L | Ghigo A | Hirsch E | Kreitmeier K | Maier LS | Rex N | Sag CM | Silengo L | Wagner S

Evidence 2552a14cf6

As expected, α-tocopherol treatment prevented ROS accumulation and the induction of anti-oxidant genes in the heart (Figure 6A, B and see Figure 8 in [37]).

Evidence 4a6c2e153a

Consistently, we measured increased lipid peroxidation in both cells and tissues exposed to free heme, which can be rescued by α-tocopherol, an agent able to react with lipid radicals and interrupt the oxidation reaction.

Evidence c633e00eae

Heme promotes endothelial dysfunction by inducing the expression of adhesion molecules and reducing nitric oxide (NO) availability, which causes vasoconstriction [9-14].

Evidence 6a862391eb

As well as NAC, Hx co-treatment significantly improved systolic Ca2+ transients and accelerated Ca2+ transient decay kinetics, which resulted in a significant improvement of cardiomyocyte contractility (Figure 4A-E).

Evidence 450903f5e9

Moreover, heme-derived ROS induce the proliferation of smooth muscle cells, that participate in vasculopathy associated with atherosclerosis and hypertension [15].

Evidence 579f51c4d8

In agreement with data on pro-oxidant effects of heme in neonatal mouse CMs (Figure 1D-F), oxidative stress was significantly increased in adult rat CMs exposed to free heme (see Figure 1 in [37]).

Evidence 5e0a188dc4

Consistently, the mRNA levels of Glutathione reductase (Gsr), -Glutamylcysteine synthetase (-Gcs) and thioredoxin reductase (Thiored red), anti-oxidant systems important in resistance of cardiac cell to oxidative damage [40, 41], were increased to a higher extent in CMs treated with either albumin heme or heme alone, compared to cells treated with Hx-heme (Figure 1F and see Figure 3 in [37]).

Evidence 393cde8bd6

These data collectively indicate that heart free heme accumulating when Hx is lost is responsible for systolic dysfunction.

Evidence 8882c0f19b

Excess production of reactive oxygen species (ROS) has been implicated in progression of chronic heart failure as well as in other cardiovascular disorders including ischemia-reperfusion injury and cardiovascular complications of hemolytic diseases [2-7].

Evidence 1f9f8552f7

Mechanistically, heme-derived ROS may directly modify Ca2+ handling proteins (such as the RyR2 or SERCA2a) [35, 57], and may also activate intracellular stress kinases, such as CaMKII [58], which in turn phosphorylate the same Ca2+ effectors and ultimately exacerbate Ca2+ mishandling.

Evidence 0a797f53b4

Hx-heme-treated CMs were protected from heme accumulation, compared to cells treated with albumin-heme or heme alone (Figure 1A), indicating that Hx prevents heme entry in cardiac cells.

Evidence a5273b36f8

Being heme a well-known pro-oxidant agent [17], we then evaluated ROS levels in CMs exposed to heme alone or bound to either Hx or albumin. In the presence of Hx-heme complexes, CMs were protected from ROS formation, if compared to CMs treated with either albumin-heme complexes or heme alone (Figure 1D).

Evidence 260a0728fc

Consistently, HO-1 mRNA and protein levels were higher in hearts from Hx-/- mice than in controls (Figure 2B). Immunohistochemistry for HO-1 on heart sections indicated higher HO-1 expression in cardiomyocytes from Hx-/- mice than in wild-type animals (Figure 2B).

Evidence d243a7e8bd

Moreover, in CMs the heme-mediated induction of the iron exporter Ferroportin (Fpn) was abrogated by Hx treatment while the down-regulation of the iron importer Transferrin receptor 1 (TfR1) was significantly reduced by Hx (see Figure 3 in [37]) further indicating that Hx limits heme-iron accumulation within the cell.

Evidence fa52e0b878

Moreover, the mRNA levels of Fpn and Flvcr1a were increased in Hx-/- mice, whereas those of the iron importers Divalent Metal Transporter 1 (Dmt1) and Tfr1 were decreased (see Figure 4 in [37]).

Evidence 0300ad7998

Consistently, Hx treatment blunted heme-mediated induction of the heme exporter Feline Leukemia Virus subgroup C Receptor 1(Flvcr1) [31, 38, 39] in H9c2 cells (see Figure 3 in [37]).

Evidence 52d6216bb0

Staining of CMs with a fluorescent probe for specific detection of mitochondrial superoxide (Mito-sox) confirmed lower oxidative stress in cells exposed to Hx-heme than in those exposed to albumin-heme or heme alone (Figure 1E).

Evidence 8dd3599914

Both ROS and lipid peroxidation were increased in the heart of Hx-/- mice compared to that of wild-type animals (Figure 2C, D).

Evidence 01f5e48370

The data were reproduced in H9c2 cells in which we were also able to demonstrate that Hx limits protein nitrosylation, another hallmark of cellular oxidative damage (see Figure 2 in [37]).

Evidence be596ad734

Consistently, the oxidative stress responsive gene Gsr was up-regulated in the heart of Hx-/- mice compared to wild-type animals (Figure 2E).

Evidence c9699eaec7

Cardiac contractility was severely impaired in 3 month-old Hx-/- mice compared to wild-type controls, as evidenced by significantly lower fractional shortening (FS) and ejection fraction (EF) (Figure 3A-C).

Evidence 92839ee6cf

Consistently, CaMKII-dependent phosphorylation of RyR2 (Ser-2814) and Phospholamban (PLB) (Thr-17) were significantly higher in Hx-/- hearts than in wild-type controls (Figure 5C, D).

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If you find BEL Commons useful in your work, please consider citing: Hoyt, C. T., Domingo-Fernández, D., & Hofmann-Apitius, M. (2018). BEL Commons: an environment for exploration and analysis of networks encoded in Biological Expression Language. Database, 2018(3), 1–11.