Effects of voluntarily consumed sweetened alcohol and naringin on cardiac function in male and female Sprague-Dawley rats.

This study assessed the impact of sweetened alcohol and naringin on cardiac function in Sprague-Dawley rats. Male (n = 40) and female (n = 40) rats were allocated to control, sweetened alcohol (SOH), naringin (NA), and sweetened alcohol with naringin (SOH + NA) groups. SOH and SOH + NA rats received 10% alcohol + 20% fructose in gelatine; SOH + NA and NA rats received 50 mg/kg naringin in gelatine daily for 10 weeks. Echocardiography was performed to assess left ventricular (LV) function. LV cardiomyocyte diameters and collagen area fraction were determined by H&E and picrosirius-red staining, respectively. In males, sweetened alcohol and naringin did not affect cardiac function. Female SOH rats had increased LV end-diastolic posterior wall (p = 0.04), relative wall thicknesses (p = 0.01), and LV cardiomyocyte diameters (p = 0.005) compared with control. Female SOH and SOH + NA had reduced lateral e' and e'/a' and increased E/e' (p < 0.0001). Female SOH (p = 0.01) and SOH + NA (p = 0.04) rats had increased LV collagen area fraction compared with controls. In males, neither sweetened alcohol nor naringin affected cardiac geometry or diastolic function. In females, sweetened alcohol induced concentric remodelling, impaired LV relaxation, and elevated filling pressures. Naringin may have the potential to improve the sweetened alcohol-induced concentric remodelling; however, it did not ameliorate diastolic dysfunction in females.

Tumor Necrosis Factor-α Mediates Inflammation-induced Early-Stage Left Ventricular Systolic Dysfunction.

ABSTRACT: Elevated systemic inflammation contributes to pathogenesis of heart failure with preserved ejection fraction (HFpEF), but molecular mechanisms are poorly understood. Although left ventricular (LV) diastolic dysfunction is the main cause of HFpEF, subclinical systolic dysfunction also contributes. We have previously shown that rats with collagen-induced arthritis (CIA) have systemic inflammation, LV diastolic dysfunction, and that increased circulating TNF-α contributes to inflammation-induced HFpEF pathogenesis, but does not mediate LV diastolic dysfunction in CIA rats. Contribution of systemic inflammation to dysfunction of the active process of LV diastolic and systolic function are unknown. In the present study, we used the CIA rat model to investigate the effects of systemic inflammation and TNF-α blockade on systolic function, and mRNA expression of genes involved in active diastolic relaxation and of myosin heavy chain (MyHC) isoforms. Collagen inoculation and TNF-α blockade did not affect LV mRNA expression of genes that mediate active LV diastolic function. Collagen-induced inflammation impaired LV global longitudinal strain ( P = 0.03) and velocity ( P = 0.04). This impairment of systolic function was prevented by TNF-α blockade. Collagen inoculation decreased mRNA expression of α-MyHC ( Myh6, P = 0.03) and increased expression of ß-MyHC ( Myh7, P = 0.0002), a marker, which is upregulated in failing hearts. TNF-α blockade prevented this MyHC isoform-switch. These results show that increased circulating TNF-α changes the relative expression of MyHC isoforms, favoring ß-MyHC, which may underlie changes in contractile function that impair systolic function. Our results indicate that TNF-α initiates early-stage LV systolic, rather than LV diastolic dysfunction.

Interleukin-6 Blockers Improve Inflammation-Induced Lipid Metabolism Impairments but Induce Liver Fibrosis in Collagen-Induced Arthritis.

BACKGROUND: Interleukin-6 (IL-6) receptor blockers improve systemic inflammation, however, their inconsistent effects on lipid metabolism and drug-induced liver injuries warrant further investigation. This study aimed to determine the effects of IL-6 receptor blocker therapy on lipid metabolism and liver morphology in collagen-induced arthritis. METHODS: Sixty three Sprague Dawley rats were divided into control (n = 24), inflammation (n = 24), and IL-6 blocker (n = 15) groups. Inflammation was induced in the inflammation and IL-6- blocker groups using Bovine type-II collagen and incomplete Freund's adjuvant. At first signs of arthritis, the IL-6 blocker group received an IL-6 blocker, tocilizumab for six weeks. Serum concentrations of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and ATP-binding cassette transporter-A1 (ABCA1) were measured. Liver fibrosis was determined by histological stains and liver enzymes were measured using the colorimetric-chemistry analyzer. RESULTS: In the inflammation group, HDL-C and ABCA1 were reduced compared to control (p < 0.0001 and p = 0.04, respectively) and IL-6 blocker (p = 0.0003 and p < 0.0001, respectively) groups. LDL-C was increased in the inflammation compared to control (p = 0.02). Markers of liver fibrosis were increased in the IL-6 blocker group compared to control and inflammation groups (picrosirius red collagen area fraction: p < 0.0001 and p = 0.0008, respectively; Masson's trichrome collagen area fraction: p = 0.0002 and p = 0.01, respectively). Alkaline phosphatase concentrations were increased in the IL-6 blocker group compared to the control (p < 0.0001) and inflammation (p = 0.002) groups. CONCLUSION: IL-6 blockers ameliorated inflammation-induced lipid metabolism impairments, however they induced liver fibrosis. Although IL-6 blockers may reduce inflammation-induced metabolic impairments in chronic inflammatory disorders, routine monitoring of liver function is warranted while on treatment.

Increased protein phosphatase 5 expression in inflammation-induced left ventricular dysfunction in rats.

BACKGROUND: Titin phosphorylation contributes to left ventricular (LV) diastolic dysfunction. The independent effects of inflammation on the molecular pathways that regulate titin phosphorylation are unclear. METHODS: We investigated the effects of collagen-induced inflammation and subsequent tumor necrosis factor-α (TNF-α) inhibition on mRNA expression of genes involved in regulating titin phosphorylation in 70 Sprague-Dawley rats. LV diastolic function was assessed with echocardiography. Circulating inflammatory markers were quantified by enzyme-linked immunosorbent assay and relative LV gene expression was assessed by Taqman® polymerase chain reaction. Differences in normally distributed variables between the groups were determined by two-way analysis of variance (ANOVA), followed by Tukey post-hoc tests. For non-normally distributed variables, group differences were determined by Kruskal-Wallis tests. RESULTS: Collagen inoculation increased LV relative mRNA expression of vascular cell adhesion molecule 1 (VCAM1), pentraxin 3 (PTX3), and inducible nitric oxide synthase (iNOS) compared to controls, indicating local microvascular inflammation. Collagen inoculation decreased soluble guanylate cyclase alpha-2 (sGCα2) and soluble guanylate cyclase beta-2 (sGCß2) expression, suggesting downregulation of nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate (NO-sGC-cGMP) signaling. Inhibiting TNF-α prevented collagen-induced changes in VCAM1, iNOS, sGCα2 and sGCß2 expression. Collagen inoculation increased protein phosphatase 5 (PP5) expression. Like LV diastolic dysfunction, increased PP5 expression was not prevented by TNF-α inhibition. CONCLUSION: Inflammation-induced LV diastolic dysfunction may be mediated by a TNF-α-independent increase in PP5 expression and dephosphorylation of the N2-Bus stretch element of titin, rather than by TNF-α-induced downregulation of NO-sGC-cGMP pathway-dependent titin phosphorylation. The steady rise in number of patients with inflammation-induced diastolic dysfunction, coupled with low success rates of current therapies warrants a better understanding of the systemic signals and molecular pathways responsible for decreased titin phosphorylation in development of LV diastolic dysfunction. The therapeutic potential of inhibiting PP5 upregulation in LV diastolic dysfunction requires investigation.

The effect of TNF-α inhibitor treatment on microRNAs and endothelial function in collagen induced arthritis.

Chronic inflammation causes dysregulated expression of microRNAs. Aberrant microRNA expression is associated with endothelial dysfunction. In this study we determined whether TNF-α inhibition impacted the expression of miRNA-146a-5p and miRNA-155-5p, and whether changes in the expression of these miRNAs were related to inflammation-induced changes in endothelial function in collagen-induced arthritis (CIA). Sixty-four Sprague-Dawley rats were divided into control (n = 24), CIA (n = 24) and CIA+etanercept (n = 16) groups. CIA and CIA+etanercept groups were immunized with bovine type-II collagen, emulsified in incomplete Freund's adjuvant. Upon signs of arthritis, the CIA+etanercept group received 10mg/kg of etanercept intraperitoneally, every three days. After six weeks of treatment, mesenteric artery vascular reactivity was assessed using wire-myography. Serum concentrations of TNF-α, C-reactive protein, interleukin-6, vascular adhesion molecule-1 (VCAM-1) and pentraxin-3 (PTX-3) were measured by ELISA. Relative expression of circulating miRNA-146a-5p and miRNA-155-5p were determined using RT-qPCR. Compared to controls, circulating miRNA-155-5p, VCAM-1 and PTX-3 concentrations were increased, and vessel relaxation was impaired in the CIA (all p<0.05), but not in the CIA+etanercept (all p<0.05) groups. The CIA group had greater miRNA-146a-5p expression compared to the CIA+etanercept group (p = 0.005). Independent of blood pressure, miRNA-146a-5p expression was associated with increased PTX-3 concentrations (p = 0.03), while miRNA-155-5p expression was associated with impaired vessel relaxation (p = 0.01). In conclusion, blocking circulating TNF-α impacted systemic inflammation-induced increased expression of miRNA-146a-5p and miRNA-155-5p, which were associated with endothelial inflammation and impaired endothelial dependent vasorelaxation, respectively.

TNF-α inhibitors reduce inflammation-induced concentric remodelling, but not diastolic dysfunction in collagen-induced arthritis.

OBJECTIVES: To determine biologic disease-modifying anti-rheumatic drug effects on inflammation-induced cardiac geometry and function changes. METHODS: Male and female Sprague-Dawley rats (n=92) were divided into four groups: control group, collagen-induced arthritis (CIA) group, anti-TNF-α group and anti-IL-6 group. Inflammation was induced by injecting bovine type-II collagen emulsified in incomplete Freund's adjuvant at the base of the tail, in all groups except the control group. Following the onset of arthritis, the anti-TNF-α group received etanercept, and the anti-IL-6 group received tocilizumab, for six weeks. Left ventricular (LV) geometry and function were assessed with echocardiography and circulating inflammatory markers were measured with ELISA. RESULTS: Relative wall thickness in the CIA and anti-IL-6 groups were increased compared to controls (p<0.001 and p=0.02, respectively). TNF-α inhibition protected against inflammation-induced LV concentric remodelling, as relative wall thickness in the anti-TNF-α group was similar to controls (p=0.55). Systolic function variables were not different between the groups. In all groups inoculated with collagen, myocardial relaxation (lateral e') were impaired compared to controls (all p<0.001). LV filling pressures (E/e') were increased in the CIA, anti-TNF-α and anti-IL-6 groups compared to controls (p<0.001, p<0.001 and p=0.05, respectively). Independent of concentric remodelling, circulating CRP concentrations were associated with decreased e' and increased E/e', while TNF-α concentrations were associated with E/A. CONCLUSIONS: TNF-α inhibition protected against inflammation-induced adverse cardiac remodelling, but not diastolic dysfunction. IL-6 receptors blocker effects on inflammation-induced cardiac changes were inconclusive. Systemic inflammation likely impacts LV concentric remodelling and diastolic dysfunction through distinct pathways.

Inflammation-induced left ventricular fibrosis is partially mediated by tumor necrosis factor-α.

OBJECTIVE: To determine the mechanisms of inflammation-induced left ventricular (LV) remodeling and effects of blocking circulating tumor necrosis factor alpha (TNF-α) in a model of systemic inflammation. METHODS: Seventy Sprague-Dawley rats were divided into three groups: the control group, the collagen-induced arthritis (CIA) group, and the anti-TNF-α group. Inflammation was induced in the CIA and anti-TNF-α groups. Following the onset of arthritis, the anti-TNF-α group received the TNF-α inhibitor, etanercept, for 6 weeks. LV geometry and function were assessed with echocardiography. Circulating inflammatory markers were measured by ELISA and LV gene expression was assessed by comparative TaqMan® polymerase chain reaction. RESULTS: The LV relative gene expression of pro-fibrotic genes, transforming growth factor ß (TGFß) (p = 0.03), collagen I (Col1) (p < 0.0001), and lysyl oxidase (LOX) (p = 0.002), was increased in the CIA group compared with controls, consistent with increased relative wall thickness (p = 0.0009). Col1 and LOX expression in the anti-TNF-α group were similar to controls (both, p > 0.05) and tended to be lower compared to the CIA group (p = 0.06 and p = 0.08, respectively), and may, in part, contribute to the decreased relative wall thickness in the anti-TNF-α group compared to the CIA group (p = 0.03). In the CIA group, the relative gene expression of matrix metalloproteinase 2 (MMP2) and MMP9 was increased compared to control (p = 0.04) and anti-TNF-α (p < 0.0001) groups, respectively. CONCLUSION: Chronic systemic inflammation induces fibrosis and dysregulated LV extracellular matrix remodeling by increasing local cardiac pro-fibrotic gene expression, which is partially mediated by TNF-α. Inflammation-induced LV diastolic dysfunction is likely independent of myocardial fibrosis.

Associations of inflammatory markers with impaired left ventricular diastolic and systolic function in collagen-induced arthritis.

BACKGROUND: High-grade inflammation may play a pivotal role in the pathogenesis of left ventricular (LV) dysfunction. Evidence to support a role of systemic inflammation in mediating impaired LV function in experimental models of rheumatoid arthritis (RA) remains limited. The aim of the present study was to determine the effects of high-grade systemic inflammation on LV diastolic and systolic function in collagen-induced arthritis (CIA). METHODS: To induce CIA, bovine type-II collagen emulsified in incomplete Freund's adjuvant was injected at the base of the tail into 21 three-month old Sprague Dawley rats. Nine-weeks after the first immunisation, LV function was assessed by pulsed Doppler, tissue Doppler imaging and Speckle tracking echocardiography. Cardiac collagen content was determined by picrosirius red staining; circulating inflammatory markers were measured using ELISA. RESULTS: Compared to controls (n = 12), CIA rats had reduced myocardial relaxation as indexed by lateral e' (early diastolic mitral annular velocity) and e'/a' (early-to-late diastolic mitral annular velocity) and increased filling pressures as indexed by E/e'. No differences in ejection fraction and LV endocardial fractional shortening between the groups were recorded. LV global radial and circumferential strain and strain rate were reduced in CIA rats compared to controls. Higher concentrations of circulating inflammatory markers were associated with reduced lateral e', e'/a', radial and circumferential strain and strain rate. Greater collagen content was associated with increased concentrations of circulating inflammatory markers and E/e'. CONCLUSION: High-grade inflammation is associated with impaired LV diastolic function and greater myocardial deformation independent of haemodynamic load in CIA rats.

Associations of inflammatory markers and vascular cell adhesion molecule-1 with endothelial dysfunction in collagen-induced arthritis.

We determined the role of high-grade inflammation on endothelial function and its association with biomarkers of endothelial dysfunction in collagen-induced arthritis. Sprague-Dawley rats were divided into a control (n = 12) or collagen-induced arthritis (CIA; n = 21) group. To induce arthritis, Bovine-type-II collagen emulsified in incomplete Freund's adjuvant was injected at the base of the tail. Nine-weeks after the primary immunisation, vascular reactivity in mesenteric and saphenous arteries was assessed using a wire-myograph. Serum concentrations of inflammatory markers (tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), interleukin 1ß (IL-1ß), C-reactive protein (CRP)) and biomarkers of endothelial dysfunction (vascular cell adhesion molecule-1 (VCAM-1) and asymmetric dimethylarginine (ADMA)) were measured by ELISA. Acetylcholine-induced relaxation in mesenteric and saphenous arteries was impaired in CIA compared to controls (P < 0.05). Responses to sodium nitroprusside were similar between controls and CIA in mesenteric arteries and marginally impaired in saphenous arteries of CIA rats. Compared to controls, TNF-α, IL-6, IL-1ß, CRP (all P < 0.00001) and VCAM-1 (P = 0.02) were elevated in CIA. TNF-α (std ß(SE) = 0.39(0.16); P = 0.03), IL-6 (std ß(SE) = 0.37(0.17); P = 0.03), IL-1ß (std ß(SE) = 0.41(0.16); P = 0.02) and CRP (std ß(SE) = 0.36(0.17); P = 0.04) were associated with VCAM-1. Associations between inflammatory markers and the maximal relaxation (Emax) to acetylcholine in mesenteric arteries were no longer significant after adjusting for VCAM-1 (except for IL-1ß). VCAM-1 was inversely associated with the Emax to acetylcholine in mesenteric (std ß(SE) = -0.49(0.16); P = 0.01) but not in saphenous arteries (std ß(SE) = -0.06(0.18); P = 0.76). In conclusion, exposure to high-grade inflammation impairs endothelial-dependent relaxation. The inflammation-induced increase in VCAM-1 concentrations may contribute to the impaired endothelium-dependent relaxation in mesenteric arteries of CIA rats.

Increased systolic blood pressure associated with hypertriglyceridemia in female Sprague-Dawley rats.

The effect of hyperlipidemia on the cardiovascular system is uncertain in females. The aim of the present study was to determine whether administration of a lipogenic diet alters cardiovascular parameters in female rats. Fifty female Sprague-Dawley rats were assigned into 2 groups of rats receiving a standard or a high-fat, high-sucrose diet (HFHS) for 6 weeks (n = 25 per group). Body mass, blood lipids concentrations, triglycerides clearance, blood pressures (BPs), systolic and diastolic functions, as well as vascular reactivity were assessed at the end of the diet intervention. At termination, body mass was similar between the 2 groups. Fasting blood triglycerides concentration (BTG) was greater in the HFHS group. Triglycerides clearance was impaired in the HFHS group. High-density lipoprotein (HDL) cholesterol concentration was lower in the HFHS group. The early-to-late diastolic filling velocity ratio (E/A) was lower in the HFHS group and negatively associated with BTG. The sensitivity (EC50) of mesenteric arteries to phenylephrine was greater in HFHS and was negatively associated with BTG, but not HDL. Systolic BP was higher in the HFHS group and was positively associated with BTG and HDL. The association between systolic BP and BTG was independent of other lipids measured. In conclusion, hypertriglyceridemia may have increased resistance arteries responsiveness to alpha-agonist and systolic BP in female rats.

Early Wave Reflection and Pulse Wave Velocity Are Associated with Diastolic Dysfunction in Rheumatoid Arthritis.

Rheumatoid arthritis (RA) impacts arterial and diastolic function. This study examined whether arterial properties can determine diastolic function in RA. In 173 RA patients, arterial function measures including carotid femoral pulse wave velocity (PWV), central systolic and pulse pressure, pulse pressure amplification, and the magnitude and timing of the forward and reflected waves were measured using applanation tonometry. Diastolic function parameters including the ratio of early-to-late transmitral velocity (E/A) and ratio of E to the mean of the lateral and septal wall myocardial tissue lengthening (e') were measured using echocardiography. The timing of the reflected wave was associated with E/A; PWV was related to E/e'. The timing of the reflected wave, forward wave magnitude, and pulse pressure amplification were associated with impaired relaxation; PWV was related to increased left ventricular (LV) filling pressure. Early wave reflection and PWV are associated with LV-impaired relaxation and increased filling pressure, respectively, in RA.

Effects of High Salt-Low Potassium Diet on Blood Pressure and Vascular Reactivity in Male Sprague Dawley Rats.

Sodium (Na) intake increases vascular reactivity. Whether low potassium (K) intake affects vascular reactivity-associated blood pressure (BP) changes is uncertain. This study aimed to determine whether Na-induced increases in BP and vascular reactivity are altered by low K intake. Male Sprague Dawley rats were assigned to 3 dietary groups for 6 weeks: a standard Na-K diet (control, n = 12), a high Na-normal K diet (HS-NormK, n = 12), and a high Na-low K diet (HS-LowK, n = 12). BP was measured at baseline and after the dietary intervention. Na and K excretions and vascular reactivity were measured after the dietary intervention. The Na/K ratio was significantly higher in the HS-LowK compared with the other groups. Systolic and diastolic BPs increased significantly in the HS-NormK and HS-LowK groups. In mesenteric arteries, the dose-response curves for phenylephrine-induced contractions shifted to the left and the EC50 (mean ± SD) was significantly lower in the HS-NormK (0.51 ± 0.17 µM, P = 0.003) and HS-LowK (0.69 ± 0.14 µM, P = 0.005) groups compared with the control (3.24 ± 0.79 µM). Systolic (r = -0.58 P = 0.002) and diastolic (r = -0.61 P = 0.001) BPs were associated with the EC50 of phenylephrine-induced contraction in mesenteric arteries. High Na intake induces increased alpha-1 receptor responsiveness in mesenteric arteries, which may be responsible for the increase in BP and is not affected by low dietary K intake.

Sex-Specific Effects of Adrenergic-Induced Left Ventricular Remodeling in Spontaneously Hypertensive Rats.

OBJECTIVE: The aim of this work was to determine whether adrenergic-induced left ventricular (LV) dilation and eccentric remodeling in pressure-overload hypertrophy is sex specific. METHODS AND RESULTS: Chronic ß-adrenoreceptor activation was produced in male and female spontaneously hypertensive rats (SHRs) by means of daily administration of isoproterenol (ISO; 0.04 mg/kg daily) from 9 to 15 months of age. LV chamber dimensions were determined in vivo by means of echocardiography and ex vivo in isolated perfused heart preparations. The acute hemodynamic response to ISO, the degree of myocardial necrosis and apoptosis, and collagen distribution were also assessed. Female SHRs demonstrated inotropic and chronotropic responses to ISO similarly to male SHRs. Compared with control subjects (saline solution vehicle), following chronic ISO administration, LV end-diastolic diameter (mm) was increased in male (ISO 7.8 ± 0.3 vs control 6.6 ± 0.2; P < .001) but not in female (ISO 6.3 ± 0.2 vs control 6.2 ± 0.2; P = .23) SHRs. Similarly, compared with control, ISO administration increased the volume intercept of the LV end-diastolic pressure-volume relation (mL) in male (ISO 0.31 ± 0.02 vs control 0.22 ± 0.01; P < .0001) but not in female (ISO 0.17 ± 0.01 vs control 0.17 ± 0.01; P = 1.00) SHRs. Relative wall thickness was also decreased in male SHRs receiving ISO but not in female SHRs receiving ISO. Chronic ISO administration increased the percentage of area covered by interstitial collagen in male but not in female SHRs. Finally, chronic adrenergic stimulation failed to influence LV chamber or myocardial systolic function in either male or female SHRs. CONCLUSIONS: Male SHRs are more susceptible to adrenergic-induced LV dilation and eccentric LV remodeling than female SHRs. These effects are associated with increased collagen deposition. In pressure-overload hypertrophy, LV dilation and eccentric LV remodeling occur before LV dysfunction in male rats.

The Impact of Different Classification Criteria Sets on the Estimated Prevalence and Associated Risk Factors of Diastolic Dysfunction in Rheumatoid Arthritis.

This study compared the estimated prevalence and potential determinants of left ventricular (LV) diastolic dysfunction upon applying different classification criteria in rheumatoid arthritis (RA). LV diastolic function was assessed echocardiographically by pulsed Doppler (E/A), tissue Doppler (E/e', lateral and septal e'), and left atrial volume index in 176 RA patients. Relationships of traditional cardiovascular risk factors and RA characteristics with LV diastolic function and dysfunction according to previous and current criteria were determined in multivariate regression models. Waist-hip ratio was associated with E/A (standardised ß (SE) = -0.28 ± 0.09, p = 0.0002) and lateral e' (standardised ß (SE) = 0.26 ± 0.09, p = 0.01); low diastolic blood pressure was related to E/e' (standardised ß (SE) = -0.16 ± 0.08, p = 0.04). Diastolic dysfunction prevalence differed upon applying previous (59%) compared to current (22%) criteria (p < 0.0001). One SD increase in waist-hip ratio was associated with diastolic dysfunction when applying current criteria (OR = 2.61 (95% CI = 1.51-4.52), p = 0.0006), whereas one SD increase in diastolic blood pressure was inversely related to diastolic dysfunction upon using previous criteria (OR = 0.57 (95% CI = 0.40-0.81), p = 0.002). In conclusion, application of current and previous diastolic dysfunction criteria markedly alters the prevalence and risk factors associated with diastolic dysfunction in RA.