Galectin-3 contributes to acute cardiac dysfunction and toxicity by increasing oxidative stress and fibrosis in doxorubicin-treated mice

BACKGROUND

Doxorubicin (DOX) leads to cardiovascular toxicity through direct cardiomyocyte injury and inflammation. We aimed to study the role of Galectin-3 (Gal-3), a β-galactosidase binding lectin associated with inflammation and fibrosis in DOX-induced acute cardiotoxicity in mice.

METHODS

Male C57 and Gal-3 knockout (KO) mice were given a single dose of DOX (15 mg/kg, i.p) or placebo. Serum creatine phosphokinase (CPK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and cardiac thiobarbituric acid-reactive substance (TBARS) were measured at 3 days to assess cardiac injury and oxidative stress. Cardiac remodeling and function were studied by echocardiography and catheterization at 7 days. Myocardial fibrosis was quantified in picrosirius red stained slices.

RESULTS

Absence of Gal-3 tended to reduce the mortality after DOX. DOX significantly increased CPK, LDH, AST and TBARS while treated Gal-3 KO mice showed reduced injury and oxidative stress. After 7 days, adverse remodeling, fibrosis and dysfunction in treated-C57 mice were severely affected while those effects were prevented by absence of Gal-3.

CONCLUSION

In summary, genetic deletion of Gal-3 prevented cardiac damage, adverse remodeling and dysfunction, associated with reduced cardiac oxidative stress and fibrosis. Understanding the contribution of GAL-3 to doxorubicin-induced cardiac toxicity reinforces its potential use as a therapeutic target in patients with several cancer types.

Studies on the contribution of PPAR Gamma to tuberculosis physiopathology

Introduction

Tuberculosis (TB) is a major health problem characterized by an immuno-endocrine imbalance: elevated plasma levels of cortisol and pro- and anti-inflammatory mediators, as well as reduced levels of dehydroepiandrosterone. The etiological agent, Mycobacterium tuberculosis (Mtb), is captured by pulmonary macrophages (Mf), whose activation is necessary to cope with the control of Mtb, however, excessive activation of the inflammatory response also leads to tissue damage. Glucocorticoids (GC) are critical elements to counteract the immunoinflammatory reaction, and peroxisome proliferator-activated receptors (PPARs) are also involved in this regard. The primary forms of these receptors are PPARϒ, PPARα, and PPARβ/δ, the former being the most involved in anti-inflammatory responses. In this work, we seek to gain some insight into the contribution of PPARϒ in immuno-endocrine-metabolic interactions by focusing on clinical studies in pulmonary TB patients and in vitro experiments on a Mf cell line.

Methods and results

We found that TB patients, at the time of diagnosis, showed increased expression of the PPARϒ transcript in their peripheral blood mononuclear cells, positively associated with circulating cortisol and related to disease severity. Given this background, we investigated the expression of PPARϒ (RT-qPCR) in radiation-killed Mtb-stimulated human Mf. The Mtb stimulation of Mf derived from the human line THP1 significantly increased the expression of PPARϒ, while the activation of this receptor by a specific agonist decreased the expression of pro- and anti-inflammatory cytokines (IL-1β and IL-10). As expected, the addition of GC to stimulated cultures reduced IL-1β production, while cortisol treatment together with the PPARϒ agonist lowered the levels of this proinflammatory cytokine in stimulated cultures. The addition of RU486, a glucocorticoid receptor antagonist, only reversed the inhibition produced by the addition of GC.

Conclusion

The current results provide a stimulating background for further analysis of the interconnection between PPARs and steroid hormones in the context of Mtb infection.

Genetic Deletion of Galectin-3 Exacerbates Age-Related Myocardial Hypertrophy and Fibrosis in Mice

BACKGROUND/AIMS

Aging is accompanied by progressive and adverse cardiac remodeling characterized by myocardial hypertrophy, fibrosis, and dysfunction. We previously reported that galectin-3 (Gal-3) is a critical regulator of inflammation and fibrosis associated with hypertensive heart disease and myocardial infarction. Nevertheless, the role and mechanism of Gal-3 in age-related cardiac remodeling have not been previously investigated. We hypothesized that Gal-3 plays a critical role in cardiac aging and that its deficiency exacerbates the underlying mechanisms of myocardial hypertrophy and fibrosis.

METHODS

Male C57BL/6 (control) (n=24) and Gal-3 knockout (KO) (n=29) mice were studied at 24 months of age to evaluate the role of Gal-3 in cardiac aging. We assessed 1) survival rate; 2) systolic blood pressure (SBP) by plethysmography; 3) myocardial hypertrophy, apoptosis, and fibrosis by quantification of histological and immunohistochemical analysis; 4) cardiac expression of angiotensin (Ang) II, Ang (1-7) by Radioimmunoassay; 5) transforming growth factor-β (TGF-β), sirtuin (SIRT) 1, SIRT 7 and metalloproteinase 9 (MMP-9) by RT-qPCR and 6) ventricular remodeling and function by echocardiography.

RESULTS

We found that aged Gal-3 KO mice had a lower survival rate and exhibited exacerbated myocardial hypertrophy and fibrosis without changes in SBP. Similarly, myocardial apoptosis and MMP-9 mRNA expression was significantly increased in the hearts of Gal-3 KO mice compared to controls. Additionally, cardiac Ang II and TGF-β expression were higher in aged Gal-3 KO mice while SIRT1 and SIRT7 expression were reduced.

CONCLUSION

Our findings strongly suggest that Gal-3 is involved in age-related cardiac remodeling by regulating critical mechanisms associated with the development of pathological hypertrophy. The gene deletion of Gal-3 reduced the lifespan and markedly increased age-dependent mechanisms of myocardial hypertrophy, apoptosis, and fibrosis, including Ang-II, TGF-β, and MMP-9. At the same time, there was diminished cardiac-specific expression of SIRT1 and SIRT7, which are extensively implicated in delaying age-dependent cardiomyopathies.

Genetic Deletion of Galectin-3 Alters the Temporal Evolution of Macrophage Infiltration and Healing Affecting the Cardiac Remodeling and Function after Myocardial Infarction in Mice

We studied the role of galectin-3 (Gal-3) in the expression of alternative activation markers (M2) on macrophage, cytokines, and fibrosis through the temporal evolution of healing, ventricular remodeling, and function after myocardial infarction (MI). C57BL/6J and Gal-3 knockout mice (Lgals3^-/-) were subjected to permanent coronary ligation or sham. We studied i) mortality, ii) macrophage infiltration and expression of markers of alternative activation, iii) cytokine, iv) matrix metalloproteinase-2 activity, v) fibrosis, and vi) cardiac function and remodeling. At 1 week post-MI, lack of Gal-3 markedly attenuated F4/80+ macrophage infiltration and significantly increased the expression of Mrc1 and Chil1, markers of M2 macrophages at the MI zone. Levels of IL-10, IL-6, and matrix metalloproteinase-2 were significantly increased, whereas tumor necrosis factor-α, transforming growth factor-β, and fibrosis were remarkably attenuated at the infarct zone. In Gal-3 knockout mice, scar thinning ratio, expansion, and cardiac remodeling and function were severely affected from the onset of MI. At 4 weeks post-MI, the natural evolution of fibrosis in Gal-3 knockout mice was also affected. Our results suggest that Gal-3 is essential for wound healing because it regulates the dynamics of macrophage infiltration, proinflammatory and anti-inflammatory cytokine expression, and fibrosis along the temporal evolution of MI in mice. The deficit of Gal-3 affected the dynamics of wound healing, thus aggravating the evolution of remodeling and function.

P6297Genetic mutation of galectin-3 altered the temporal evolution of macrophage polarization and healing affecting the post myocardial infarct remodeling in mice

Background

Myocardial infarction (MI) is a dynamic process that leads to ventricular remodeling (VR) and largely to heart failure (HF). Previous studies established that Galectin-3 (Gal-3) is highly increased in the infarct zone from the beginning of MI and also that it is a prognostic marker of HF.

Purpose

We aimed to study the effects of genetic deletion of Gal-3 on macrophage (MΦ) infiltration, cytokines expression, fibrosis and MMP-2 activity as well as VR and function after MI in mice.

Methods

Male C57BL/6J and Gal-3 KO mice were subjected to permanent coronary ligature or sham. At 1 week post-MI LV function and VR were studied by echocardiography. We also studied in the infarct zone: 1) F4/80+ MΦ infiltration by flow cytometry; 2) M2 macrophage polarization by detection of mannose receptor (MR) and chitinase-3-like protein-3 (YM1) phenotype markers by rt-qPCR; 3) mRNA expression of TNF-α, IL-6, IL-10 and TGF-β; 4) MMP-2 activity by zymography and 5) fibrosis by histology.

Results

Results are expressed as X±SEM; *p<0.05 C57 MI vs Gal-3 KO MI. After 1 week post-MI, the pulmonary congestion assessed by the lung weight/body weight ratio (mg/g) was 9±0.4, 8±0.5 and 9±0.4 in C57 sham, Gal-3 KO sham and C57 MI, respectively, nevertheless it was severely increased to 15±1.2* in infarcted Gal-3 KO mice. MΦ infiltration, cytokine expression and MMP-2 activity in the infarct zone are shown in the table.

Table 1 Groups F4/80+ MR YM1 TNF-α IL-6 IL-10 TGF-β MMP-2 MΦ (%) (A.U.) (A.U.) (A.U.) (A.U.) (A.U.) (A.U.) (A.U.) C57 MI 5.6±0.9 (8) 0.5±0.2 (3) 1.7±0.4 (3) 26±0.3 (3) 1.7±0.5 (3) 0.7±0.03 (3) 1.8±0.5 (3) 1±0.1 (5) Gal-3 KO MI 2.6±0.4* (8) 1.8±0.4*(8) 4.2±0.4* (8) 0.4±0.5* (8) 6.7±0.9 * (8) 2.8±0.3 * (8) 0.5±0.2 * (8) 2±0.4* (6) A.U.: Arbitrary units. In MR, YM1, TNF-α, IL-6, IL-10 and TGF-β represent mRNA expression. In MMP-2 represent gelatinolytic activity. Number of samples is shown between parentheses.

After 1 week post-MI, LV end diastolic dimension was increased from 4.4±0.1 to 4.8±0.2* at the same time that ejection fraction (%) was significantly reduced from 47±2 to 38±3* in C57+MI (13) and Gal-3 KO+MI (16) respectively. Collagen concentration in the infarct zone was significantly reduced from 30±1.2% (6) to 17±0.5* % (8) in C57 and Gal-3 KO respectively.

Conclusion(s)

Gal-3 is an essential regulatory factor for the early wound healing since it regulates the dynamics of the reparative process through the phenotypic profile of MΦ, the pro- and anti-inflammatory cytokines expression and fibrosis along the temporal evolution of MI in mice. The deficit of Gal-3 diminished the infiltration of MΦ altering its phenotypic polarization and consequently, the dynamics of the wound healing as well as aggravating the functional and structural evolution of cardiac remodeling.

Acknowledgement/Funding

Argentine Agency for Promotion of Science and Technology (PICT 2014-2320), University of Buenos Aires (UBACyT 20020170100619BA)

PPARγ ligand treatment inhibits cardiac inflammatory mediators induced by infection with different lethality strains of Trypanosoma cruzi

Trypanosoma cruzi (T. cruzi), the etiological agent of Chagas' disease, causes cardiac alterations in the host. Although the main clinical manifestations arise during the chronic stage, the mechanisms leading to heart damage develop early during infection. In fact, an intense inflammatory response is observed from acute stage of infection. Recently, peroxisome proliferator-activated receptors (PPARs) have attracted research interest due to their participation in the modulation of inflammation. In this work we addressed the role of 15-Deoxy-∆(12,14) ProstaglandinJ2 (15dPGJ2), a PPARγ natural ligand in the regulation of inflammatory mediators, in acute and chronic experimental mouse models of Chagas' disease with the RA and K98 T. cruzi strains, respectively. This work demonstrates that 15dPGJ2 treatment inhibits the expression and activity of inducible nitric oxide synthase (NOS2) as well as TNF-α and IL-6 mRNA levels. Also, expression and activity of metalloproteinases 2 (MMP-2) and 9 (MMP9) were inhibited by 15dPGJ2. Moreover GW9662, a specific PPARγ antagonist, revealed the participation of other signaling pathways since, in GW9662 presence, 15dPJG2 had a partial effect on the inhibition of inflammatory parameters in the acute model of infection. Accordingly, NF-κB activation was demonstrated, assessing p65 nuclear translocation in the hearts of infected mice with both T. cruzi strains. Such effect was inhibited after 15dPGJ2 treatment. Our findings support the concept that in vivo PPARγ and NF-κB pathways are implicated in the inhibitory effects of 15dPGJ2 on inflammatory mediators at different times depending on whether the infection is caused by the lethal or non-lethal T. cruzi strain.

Modulation of inflammatory response and parasitism by 15-Deoxy-Δ(12,14) prostaglandin J(2) in Trypanosoma cruzi-infected cardiomyocytes

Trypanosoma cruzi infection produces an intense inflammatory response in diverse tissues including the heart. The inflammatory reaction is critical for the control of the parasites' proliferation and evolution of Chagas disease. 15-Deoxy-Δ(12,14) prostaglandin J(2) (15dPGJ2) can repress the inflammatory response in many experimental models. However, the precise role of peroxisome proliferator-activated receptor γ (PPARγ) ligands in T. cruzi infection or in Chagas disease is poorly understood. This work reports the first evidence that 15dPGJ2 treatment increases the number of intracellular parasites as shown by fluorescence microscopy and it is also able to inhibit the expression and activity of different inflammatory enzymes such as inducible nitric oxide synthase (NOS-2), matrix metalloproteinases 2 and 9 (MMP-2, MMP-9), as well as pro-inflammatory cytokine (TNF-α and IL-6) mRNA expression in neonatal mouse cardiomyocytes after T. cruzi infection. Transfection of cardiomyocytes with small interfering RNA (siRNA) induces silencing of PPARγ and impairs the effects of 15dPGJ2 on the modulation of pro-inflammatory enzymes. Moreover, transfection restores the ability of these cells to control the intracellular growth of T. cruzi. We also found that PPARγ-independent pathways are involved, since 15dPGJ2 also exerts its effect through extracellular signal-regulated kinases-mitogen-activated protein kinase (Erk-MAPK) and nuclear factor-κB (NF-κB). The use of specific pharmacological inhibitors confirmed these findings. Our data point out that 15dPGJ2 is a potent modulator of the inflammatory process and regulator of parasites growth through PPARγ-dependent and independent (Erk-MAPK- and NF-κB) pathways in T. cruzi infected neonatal cardiac cells.