Differential effects of olmesartan and ramipril on inflammatory response after myocardial infarction in rats

Myocardial tissue changes detected by cardiac MRI in a patient with suspected systemic sarcoidosis

BACKGROUND

The role of cardiac magnetic resonance imaging in the early management of chronic cardiac inflammatory conditions is growing. Our case enlightens the benefit of quantitative mapping in the monitoring and treatment guidance in systemic sarcoidosis.

CASE PRESENTATION

We report about a 29-year-old man with an ongoing dyspnea and bihilar lymphadenopathy, suggesting sarcoidosis. Cardiac magnetic resonance showed high mapping values, but no scarring. In follow-ups, cardiac remodeling was noted; cardioprotective treatment normalized cardiac function and mapping markers. Definitive diagnosis was achieved in extracardiac lymphatic tissue during a relapse.

CONCLUSION

This case shows the role that mapping markers can play in the detection and treatment at early stage of systemic sarcoidosis.

Early ACEI/ARB use and in-hospital outcomes of acute myocardial infarction patients with systolic blood pressure <100 mmHg and undergoing percutaneous coronary intervention: Findings from the CCC-ACS project

Background

Few studies have evaluated whether acute myocardial infarction (AMI) patients with relatively low blood pressure benefit from early ACEI/ARB use in the era of percutaneous coronary intervention (PCI).

Objectives

This study evaluated the associations of ACEI/ARB use within 24 h of admission with in-hospital outcomes among AMI patients with SBP < 100 mmHg and undergoing PCI.

Methods

This study was based on the Improving Care for Cardiovascular Disease in China-ACS project, a collaborative registry and quality improvement project of the American Heart Association and the Chinese Society of Cardiology. Between November 2014 and December 2019, a total of 94,623 patients with AMI were enrolled. Of them, 4,478 AMI patients with SBP < 100 mmHg and undergoing PCI but without clinically diagnosed cardiogenic shock at admission were included. Multivariable logistic regression and propensity score-matching analysis were used to evaluate the association between early ACEI/ARB use and in-hospital major adverse cardiac events (MACEs), a combination of all-cause death, cardiogenic shock, and cardiac arrest.

Results

Of AMI patients, 24.41% (n = 1,093) were prescribed ACEIs/ARBs within 24 h of admission. Patients with early ACEI/ARB use had a significantly lower rate of MACEs than those without ACEI/ARB use (1.67% vs. 3.66%, p = 0.001). In the logistic regression analysis, early ACEI/ARB use was associated with a 45% lower risk of MACEs (odds ratio: 0.55, 95% CI: 0.33-0.93; p = 0.027). Further propensity score-matching analysis still showed that patients with early ACEI/ARB use had a lower rate of MACEs (1.96% vs. 3.93%, p = 0.009).

Conclusion

This study found that among AMI patients with an admission SBP < 100 mmHg undergoing PCI, early ACEI/ARB use was associated with better in-hospital outcomes. Additional studies of the early use of ACEIs/ARBs in AMI patients with relatively low blood pressure are warranted.

Immunomodulatory Activity of the Most Commonly Used Antihypertensive Drugs-Angiotensin Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers

This review article is focused on antihypertensive drugs, namely angiotensin converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), and their immunomodulatory properties reported in hypertensive patients as well as in experimental settings involving studies on animal models and cell lines. The immune regulatory action of ACEI and ARB is mainly connected with the inhibition of proinflammatory cytokine secretion, diminished expression of adhesion molecules, and normalization of CRP concentration in the blood plasma. The topic has significant importance in future medical practice in the therapy of patients with comorbidities with underlying chronic inflammatory responses. Thus, this additional effect of immune regulatory action of ACEI and ARB may also benefit the treatment of patients with metabolic syndrome, allergies, or autoimmune disorders.

Immunopharmacology of Post-Myocardial Infarction and Heart Failure Medications

The immune system responds to acute tissue damage after myocardial infarction (MI) and orchestrates healing and recovery of the heart. However, excessive inflammation may lead to additional tissue damage and fibrosis and exacerbate subsequent functional impairment, leading to heart failure. The appreciation of the immune system as a crucial factor after MI has led to a surge of clinical trials investigating the potential benefits of immunomodulatory agents previously used in hyper-inflammatory conditions, such as autoimmune disease. While the major goal of routine post-MI pharmacotherapy is to support heart function by ensuring appropriate blood pressure and cardiac output to meet the demands of the body, several drug classes also affect a range of immunological pathways and modulate the post-MI immune response, which is crucial to take into account when designing future immunomodulatory trials. This review outlines how routine post-MI pharmacotherapy affects the immune response and may thus influence post-MI outcomes and development towards heart failure. Current key drug classes are discussed, including platelet inhibitors, statins, β-blockers, and renin⁻angiotensin⁻aldosterone inhibitors.

Qiliqiangxin Protects against Renal Injury in Rat with Cardiorenal Syndrome Type I through Regulating the Inflammatory and Oxidative Stress Signaling

Cardiorenal syndrome (CRS) is a frequently encountered clinical condition when the dysfunction of either the heart or kidneys amplifies the failure progression of the other organ. CRS remains a major global health problem. Qiliqiangxin (QLQX) is a traditional Chinese herbs medication, which can improve cardiac function, urine volume, and subjective symptoms in patients with chronic heart failure. In the present study, we aim to investigate the role of QLQX in the treatment of CRS type I and the possible mechanism through establishment of a rat model of myocardial infarction. Rats in CRS-Q group were orally treated with QLQX daily for 2 weeks or 4 weeks, while in sham group and CRS-C group were treated with saline at the same time. Enzyme-linked immunosorbent assay (ELISA) analysis showed that QLQX significantly reduced the levels of angiotensin II (AngII), brain natriuretic peptides (BNP), creatinine (CRE), cystatin C (CysC), tumor necrosis factor (TNF)-α, interleukin (IL)-6, microalbuminuria (MAU), and neutrophil gelatinase-associated lipocalin (NGAL) in plasma induced by myocardial infarction. Western blot analysis showed that QLQX significantly reduced the expressions of AngII, non-phagocytic cell oxidase (NOX)2, and B-cell lymphoma (Bcl)2 associated X protein (Bax), and increased the expressions of Bcl2 and Angiotensin II Type 1 receptor (ATR) in the kidney as compared with the CRS-C group. Fluorescence microscopy showed that the content of reactive oxygen species (ROS) was significantly reduced in the kidney as compared with the CRS-C group. We also examined the apoptosis level in kidney by using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining, and the result showed that QLQX significantly reduced the apoptosis level in kidney induced by myocardial infarction. Taken together, we suggest that QLQX may be a potentially effective drug for the treatment of CRS by regulating inflammatory/oxidative stress signaling.

Lack of vitamin D signalling per se does not aggravate cardiac functional impairment induced by myocardial infarction in mice

Epidemiological studies have linked vitamin D deficiency to an increased incidence of myocardial infarction and support a role for vitamin D signalling in the pathophysiology of myocardial infarction. Vitamin D deficiency results in the development of secondary hyperparathyroidism, however, the role of secondary hyperparathyroidism in the pathophysiology of myocardial infarction is not known. Here, we aimed to explore further the secondary hyperparathyroidism independent role of vitamin D signalling in the pathophysiology of myocardial infarction by inducing experimental myocardial infarction in 3-month-old, male, wild-type mice and in mice lacking a functioning vitamin D receptor. In order to prevent secondary hyperparathyroidism in vitamin D receptor mutant mice, all mice were maintained on a rescue diet enriched with calcium, phosphorus, and lactose. Surprisingly, survival rate, cardiac function as measured by echocardiography and intra-cardiac catheterisation and cardiomyocyte size were indistinguishable between normocalcaemic vitamin D receptor mutant mice and wild-type controls, 2 and 8 weeks post-myocardial infarction. In addition, the myocardial infarction-induced inflammatory response was similar in vitamin D receptor mutants and wild-type mice, as evidenced by a comparable upregulation in cardiac interleukin-1-β and tumor-necrosis-factor-α mRNA abundance and similar elevations in circulating interleukin-1-β and tumor-necrosis-factor-α. Our data suggest that the lack of vitamin D signalling in normocalcaemic vitamin D receptor mutants has no major detrimental effect on cardiac function and outcome post-myocardial infarction. Our study may have important clinical implications because it suggests that the secondary hyperparathyroidism induced by vitamin D deficiency, rather than the lack of vitamin D signalling per se, may negatively impact cardiac function post-myocardial infarction.

Ramipril and haloperidol as promising approaches in managing rheumatoid arthritis in rats

Rheumatoid arthritis (RA) is a challenging autoimmune disorder, whose treatments usually cause severe gastrointestinal, renal and other complications. We aimed to evaluate the beneficial anti-arthritic effects of an angiotensin converting enzyme (ACE) inhibitor, ramipril and a dopamine receptor blocker, haloperidol, on Complete Freund's Adjuvant-induced RA in adult female albino rats. Rats were allocated into a normal control group, an arthritis control group, two reference treatment groups receiving dexamethasone (1.5 mg/kg/day) and methotrexate (1 mg/kg/day), and two treatment groups receiving ramipril (0.9 mg/kg/day) and haloperidol (1 mg/kg/day). Serum rheumatoid factor, matrix metalloprotinease-3 (MMP-3) and cartilage oligomeric matrix protein as specific rheumatoid biomarkers, serum immunoglobulin G and antinuclear antibody as immunological biomarkers, serum tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10) as immunomodulatory cytokines, serum myeloperoxidase and C-reactive protein as inflammatory biomarkers, as well as malondialdehyde and glutathione reduced (GSH) as oxidative stress biomarkers were assessed. A histopathological study on joints and spleens was performed to support the results of biochemical estimations. Ramipril administration significantly corrected all the measured biomarkers, being restored back to normal levels except for MMP-3, TNF-α and IL-10. Haloperidol administration restored all the measured biomarkers back to normal levels except for TNF-α, IL-10 and GSH. In conclusion, ACE inhibitors represented by ramipril and dopamine receptor blockers represented by haloperidol may represent new promising protective strategies against RA, at least owing to their immunomodulatory, anti-inflammatory and antioxidant potentials.

Qiliqiangxin inhibits angiotensin II-induced transdifferentiation of rat cardiac fibroblasts through suppressing interleukin-6

Qiliqiangxin (QL), a traditional Chinese medicine, had long been used to treat chronic heart failure. Recent studies revealed that differentiation of cardiac fibroblasts (CFs) into myofibroblasts played an important role in cardiac remodelling and development of heart failure, however, little was known about the underlying mechanism and whether QL treatment being involved. This study aimed to investigate the effects of QL on angiotensin II (AngII)-induced CFs transdifferentiation. Study was performed on in vitro cultured CFs from Sprague–Dawley rats. CFs differentiation was induced by AngII, which was attenuated by QL through reducing transforming growth factor-β₁ (TGF-β₁) and α-smooth muscle actin (α-SMA). Our data showed that AngII-induced IL-6 mRNA as well as typeI and typeIII collagens were reduced by QL. IL-6 deficiency could suppress TGF-β₁ and α-SMA, and both IL-6 siRNA and QL-mediated such effect was reversed by foresed expression of recombined IL-6. Increase in actin stress fibres reflected the process of CFs differentiation, we found stress fibres were enhanced after AngII stimulation, which was attenuated by pre-treating CFs with QL or IL-6 siRNA, and re-enhanced after rIL-6 treatment. Importantly, we showed that calcineurin-dependent NFAT3 nuclear translocation was essential to AngII-mediated IL-6 transcription, QL mimicked the effect of FK506, the calcineurin inhibitor, on suppression of IL-6 expression and stress fibres formation. Collectively, our data demonstrated the negative regulation of CFs differentiation by QL through an IL-6 transcriptional mechanism that depends on inhibition of calcineurin/NFAT3 signalling.

Olmesartan decreased levels of IL-1β and TNF-α, down-regulated MMP-2, MMP-9, COX-2, RANK/RANKL and up-regulated SOCs-1 in an intestinal mucositis model

Methotrexate (MTX) is a pro-oxidant compound that depletes dihydrofolate pools and is widely used in the treatment of leukaemia and other malignancies. The efficacy of methotrexate is often limited by mucositis and intestinal injury, which are major causes of morbidity in children and adults. The aim of this study was to evaluate the effect of olmesartan (OLM), an angiotensin II receptor antagonist, on an Intestinal Mucositis Model (IMM) induced by MTX in Wistar rats. IMM was induced via intraperitoneal (i.p.) administration of MTX (7 mg/kg) for three consecutive days. The animals were pre-treated with oral OLM at 0.5, 1 or 5 mg/kg or with vehicle 30 min prior to exposure to MTX. Small intestinal homogenates were assayed for levels of the IL-1β, IL-10 and TNF-α cytokines, malondialdehyde and myeloperoxidase activity. Additionally, immunohistochemical analyses of MMP-2, MMP-9, COX-2, RANK/RANKL and SOCS-1 and confocal microscopy analysis of SOCS-1 expression were performed. Treatment with MTX + OLM (5 mg/kg) resulted in a reduction of mucosal inflammatory infiltration, ulcerations, vasodilatation and haemorrhagic areas (p<0.05) as well as reduced concentrations of MPO (p<0.001) and the pro-inflammatory cytokines IL-1β (p<0.001) and TNF-a (p<0.01), and increase anti-inflammatory cytocine IL-10 (p<0.05). Additionally, the combined treatment reduced expression of MMP-2, MMP-9, COX-2, RANK and RANKL(p<0.05) and increased cytoplasmic expression of SOCS-1 (p<0.05). Our findings confirm the involvement of OLM in reducing the inflammatory response through increased immunosuppressive signalling in an IMM. We also suggest that the beneficial effect of olmesartan treatment is specifically exerted during the damage through blocking inflammatory cytocines.

Olmesartan prevents cardiac rupture in mice with myocardial infarction by modulating growth differentiation factor 15 and p53

BACKGROUND AND PURPOSE

Cardiac rupture is a catastrophic complication that occurs after acute myocardial infarction (MI) and, at present, there are no effective pharmacological strategies for preventing this condition. Here we investigated the effect of the angiotensin II receptor blocker olmesartan (Olm) on post-infarct cardiac rupture and its underlying mechanisms of action.

EXPERIMENTAL APPROACH

C57Bl/6 mice with MI were treated with Olm, aldosterone (Aldo) or vehicle. Cultured neonatal cardiomyocytes and fibroblasts were exposed to normoxia or anoxia and treated with angiotensin II (Ang II), RNH6270 (active ingredient of Olm) or Aldo.

KEY RESULTS

The mortality rate and incidence of cardiac rupture in MI mice during the first week in the Olm-treated group were significantly lower than in the vehicle-treated group. Olm or RNH6270 reduced myeloperoxidase staining in the infarcted myocardium, decreased apoptosis in cultured cardiomyocytes and fibroblasts, as assessed by Hoechst staining and TUNEL assay, attenuated the accumulation of p53 and phosphorylated p53 and cleaved caspase 3 induced by MI or Ang II, as assessed by Western blotting, and up-regulated growth differentiation factor-15 (GDF-15). In cultured cardiomyocytes and fibroblasts, treatment with Ang II, Aldo or anoxia significantly down-regulated the expression of GDF-15.

CONCLUSIONS AND IMPLICATIONS

Olm prevents cardiac rupture through inhibition of apoptosis and inflammation, which is attributable to the down-regulation of p53 activity and up-regulation of GDF-15. Our findings suggest that early administration of an AT1 receptor anatagonist to patients with acute MI is a potential preventive approach for cardiac rupture.

The association between smoking quantity and hypertension mediated by inflammation in Chinese current smokers

OBJECTIVES

Previous studies indicated that cigarette smokers were more likely to develop hypertension, and both smoking and hypertension were associated with inflammation. Whether inflammation mediates the relationship of them is unclear. This study aims to examine whether inflammation mediates the association between smoking and hypertension.

METHODS

Nine hundred and eighty-four Chinese current smokers from a community-based chronic diseases survey in Guangzhou and Zhuhai were interviewed about sociodemographics, smoking, chronic conditions, and other health-related variables. Hypertension was defined according to 2007 European Society of Hypertension and European Society of Cardiology (ESH-ESC) Practice Guidelines. Inflammatory markers including C-reactive protein (CRP), interleukin (IL)-6, IL-1β, monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), and vascular cell adhesion molecule-1 (VCAM-1) were measured by flow cytometry. Logistic regressions were performed to assess the mediation of inflammation on the relationship between smoking quantity and hypertension.

RESULTS

We observed a positive association between smoking quantity and hypertension (P<0.05). After controlling for potential confounders, daily cigarette consumption was significantly associated with higher level of CRP and VCAM-1 and lower level of TNF-α among six measured inflammatory markers, and the current smokers with hypertension had significantly higher level of MCP-1 and CRP than those smokers who were normotensive. Furthermore, the association between smoking quantity and hypertension was mediated by CRP, which accounted for 58.59% of the estimated causal effect of smoking on hypertension.

CONCLUSION

We have confirmed previous observations that smoking quantity was positively associated with hypertension, and the results of our study suggested that the association between smoking and hypertension was probably mediated by CRP.

Activation of renal angiotensin type 1 receptor contributes to the pathogenesis of progressive renal injury in a rat model of chronic cardiorenal syndrome

Although chronic cardiac dysfunction is known to progressively exacerbate renal injury, a condition known as type 2 cardiorenal syndrome (CRS), the mechanism responsible is largely unknown. The present study was undertaken to clarify the mechanism of renal injury in rats with both unilateral nephrectomy (NX) and surgically induced myocardial infarction (MI), corresponding to a model of type 2 CRS. Compared with a control group, rats with both MI and NX (MI+NX) exhibited progressive proteinuria during the experimental period (34 wk after MI surgery), whereas proteinuria was not observed in rats with MI alone and was moderate in rats with NX alone. The proteinuria in rats with MI+NX was associated with renal lesions such as glomerulosclerosis and infiltration of mononuclear cells and upregulation of the renal proinflammatory and -fibrotic cytokine and angiotensin II type 1a receptor (AT1aR) genes. In contrast, plasma renin activity was lowered in rats with MI+NX. Immunohistochemistry revealed that the increased AT1R protein was present mainly in renal interstitial mononuclear cells. Olmesartan medoxomil, an AT1R blocker, markedly reduced the proteinuria and infiltration of mononuclear cells, whereas spironolactone, a mineralocorticoid receptor blocker, did not. The present findings demonstrate the pathogenetic role of renal interstitial AT1R signaling in a model of type 2 CRS, providing evidence that AT1R blockade can be a useful therapeutic option for this syndrome.

Influence of ramiprilat and losartan on ischemia reperfusion injury in rat hearts

Hypothesis/introduction: Our aim was to investigate whether a non-hypotensive dose of ramiprilat and losartan has myocardial protective effects during myocardial ischemia/reperfusion in vivo.

Materials and methods: Three groups of rats were given 10 mg/kg per day of losartan for one (L-1W), four (L-4W) or 10 (L-10W) weeks. Another three groups were given 50 µg/kg per day of ramiprilat for one (R-1W), four (R-4W) or 10 (R-10W) weeks. The animals underwent 30 min of left anterior descending artery occlusion and subsequent reperfusion for 120 min.

Results: Myocardial infarct size (IS) was reduced in R-1W (28.4 ± 6.3%, p < 0.001), R-4W (27.8 ± 7.4, p < 0.001), L-4W (31.8 ± 6%, p < 0.05) and L-10W (25.3 ± 5.7, p < 0.001) groups compared with a saline group (48.3 ± 7.8%). A significant reduction in the number of ventricular ectopic beats (VEBs) was noted in groups R-1W (209 ± 41, p < 0.01), R-4W (176 ± 39, p < 0.01), L-4W (215 ± 52, p < 0.05) and L-10W (191 ± 61, p < 0.01 vs. saline 329 ± 48). The incidence of irreversible ventricular fibrillation (VF) and mortality were decreased significantly only in L-10W group.

There were no significant decreases in episodes of VT, the incidence of irreversible VF and mortality in all of the groups treated with ramiprilat.

Conclusion: These data indicate that losartan and ramiprilat protect the heart against ischemia/reperfusion injury independently of their hemodynamic effects but in a time-dependent manner.

Patterning human stem cells and endothelial cells with laser printing for cardiac regeneration

Recent study showed that mesenchymal stem cells (MSC) could inhibit apoptosis of endothelial cells in hypoxic condition, increase their survival, and stimulate the angiogenesis process. In this project we applied Laser-Induced-Forward-Transfer (LIFT) cell printing technique and prepared a cardiac patch seeded with human umbilical vein endothelial cells (HUVEC) and human MSC (hMSC) in a defined pattern for cardiac regeneration. We seeded HUVEC and hMSC in a defined pattern on a Polyester urethane urea (PEUU) cardiac patch. On control patches an equal amount of cells was randomly seeded without LIFT. Patches were cultivated in vitro or transplanted in vivo to the infarcted zone of rat hearts after LAD-ligation. Cardiac performance was measured by left ventricular catheterization 8 weeks post infarction. Thereafter hearts were perfused with fluorescein tomato lectin for the assessment of functional blood vessels and stored for histology analyses. We demonstrated that LIFT-derived cell seeding pattern definitely modified growth characteristics of co-cultured HUVEC and hMSC leading to increased vessel formation and found significant functional improvement of infarcted hearts following transplantation of a LIFT-tissue engineered cardiac patch. Further, we could show enhanced capillary density and integration of human cells into the functionally connected vessels of murine vascular system. LIFT-based Tissue Engineering of cardiac patches for the treatment of myocardial infarction might improve wound healing and functional preservation.

Potential role of renin-angiotensin system blockade for preventing myocardial ischemia/reperfusion injury and remodeling after myocardial infarction

Experimental and clinical studies have demonstrated that myocardial ischemia induces activation of various components of the renin-angiotensin system (RAS), including angiotensinogen, renin, angiotensin-converting enzyme (ACE), angiotensins, and angiotensin receptors, in the acute phase of myocardial infarction and the postinfarction remodeling process. Pharmacological inhibition of the RAS by administration of renin inhibitors, ACE inhibitors, and angiotensin receptor blockers has shown beneficial effects on the pathological processes of myocardial infarction in both experimental animal studies and clinical trials. However, the potential mechanisms responsible for the cardioprotection of RAS inhibition remain unclear. In this review, we discuss roles of RAS blocking in the prevention of myocardial ischemia/reperfusion injury and postinfarction remodeling.

Ramipril mitigates radiation-induced impairment of neurogenesis in the rat dentate gyrus

BACKGROUND

Sublethal doses of whole brain irradiation (WBI) are commonly administered therapeutically and frequently result in late delayed radiation injuries, manifesting as severe and irreversible cognitive impairment. Neural progenitors within the subgranular zone (SGZ) of the dentate gyrus are among the most radiosensitive cell types in the adult brain and are known to participate in hippocampal plasticity and normal cognitive function. These progenitors and the specialized SZG microenvironment required for neuronal differentiation are the source of neurogenic potential in the adult dentate gyrus, and provide a continuous supply of immature neurons which may then migrate into the adjacent granule cell layer to become mature granule cell neurons. The extreme radiosensitivity of these progenitors and the SGZ microenvironment suggests the hippocampus as a prime target for radiation-induced cognitive impairment. The brain renin-angiotensin system (RAS) has previously been implicated as a potent modulator of neurogenesis within the SGZ and selective RAS inhibitors have been implicated as mitigators of radiation brain injury. Here we investigate the angiotensin converting enzyme (ACE) inhibitor, ramipril, as a mitigator of radiation injury in this context.

METHODS

Adult male Fisher 344 rats received WBI at doses of 10 Gy and 15 Gy. Ramipril was administered beginning 24 hours post-WBI and maintained continuously for 12 weeks.

RESULTS

Ramipril produced small but significant reductions in the deleterious effects of radiation on progenitor proliferation and neuronal differentiation in the rat dentate gyrus following 10 Gy-WBI, but was not effective following 15 Gy-WBI. Ramipril also reduced the basal rate of neurogenesis within the SGZ in unirradiated control rats.

CONCLUSIONS

Our results indicate that chronic ACE inhibition with ramipril, initiated 24 hours post-irradiation, may reduce apoptosis among SGZ progenitors and/or inflammatory disruption of neurogenic signaling within SGZ microenvironment, and suggest that angiotensin II may participate in maintaining the basal rate of granule cell neurogenesis.

Effect of early versus late AT(1) receptor blockade with losartan on postmyocardial infarction ventricular remodeling in rabbits

To characterize the temporal activation of the renin-angiotensin system after myocardial infarction (MI) in rabbits, we examined cardiac ANG II type 1 receptor (AT(1)R) expression and ANG II levels from 3 h to 35 days. The effects of losartan (12.5 mg.kg(-1).day(-1)) on functional and histomorphometric parameters when treatment was initiated early (3 h) and late (day 15) post-MI and maintained for different periods of time [short term (4 days), midterm (20 days), and long term (35 days)] were also studied. AT(1)R expression increased in the MI zone at 15 and 35 days (P < 0.05). ANG II levels increased (P < 0.05) in the non-MI zone at 24 h and in the MI zone as well as in plasma at 4 days and then progressively decreased until 35 days. The survival rate was significantly lower in untreated MI and early long-term-treated animals. Diastolic pressure-volume curves in MI at 35 and 56 days shifted to the right (P < 0.05). This shift was even more pronounced in long-term-treated groups (P < 0.05). Contractility decreased (P < 0.05 vs. sham) in the untreated and long-term-treated groups and was attenuated in the midterm-treated group. The early administration of losartan reduced RAM 11-positive macrophages from 4.15 +/- 0.05 to 3.05 +/- 0.02 cells/high-power field (HPF; P < 0.05) and CD45 RO-positive lymphocytes from 2.23 +/- 0.05 to 1.48 +/- 0.01 cells/HPF (P < 0.05) in the MI zone at 4 days. Long-term treatment reduced the scar collagen (MI: 70.50 +/- 2.35% and MI + losartan: 57.50 +/- 2.48, P < 0.05), determined the persistency of RAM 11-positive macrophages (3.02 +/- 0.13 cells/HPF) and CD45 RO-positive lymphocytes (2.77 +/- 0.58 cells/HPF, P < 0.05 vs. MI), and reduced the scar thinning ratio at 35 days (P < 0.05). Consequently, the temporal expressions of cardiac AT(1)R and ANG II post-MI in rabbits are different from those described in other species. Long-term treatment unfavorably modified post-MI remodeling, whereas midterm treatment attenuated this harmful effect. The delay in wound healing (early reduction and late persistency of inflammatory infiltrate) and adverse remodeling observed in long-term-treated animals might explain the unfavorable effect observed in rabbits.

Angiotensin II receptor antagonism reverts the selective cardiac BNP upregulation and secretion observed in myocarditis

The cardiac natriuretic peptides atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) are discoordinately regulated in myocardial inflammation associated with acute allograft rejection in humans and during in vitro exposure of cardiocyte cultures to some proinflammatory cytokines. We used experimental autoimmune myocarditis (EAM) to determine whether the discoordinate regulation of ANF and BNP was specific to the situations above or was generally associated with other types of myocardial inflammation. The dependency of this process to angiotensin signaling was also determined, given that previous work demonstrated beneficial effects of the angiotensin receptor blocker olmesartan in myocarditis. Histopathological changes, plasma and cardiac ANF, BNP, and selected cytokines gene expression as well as plasma cytokine levels using a cytokine array were determined in EAM, angiotensin receptor blocker-treated, and control rats. It was found that EAM specifically increases BNP but not ANF circulating levels, thus mimicking the findings in acute cardiac allograft rejection and the effect of some proinflammatory cytokines on cardiocyte cultures in vitro. Plasma cytokine array and real-time PCR revealed that lipopolysaccharide-induced CXC chemokine, monocyte chemotactic protein-1, and tissue inhibitor of metalloproteinase-1 were increased in plasma and in the myocardium of EAM rats. Olmesartan treatment reversed virtually all neuroendocrine and histopathological cardiac changes induced by EAM, thus providing a mechanistic insight into this phenomenon. It is concluded that the inflammatory process contributes specific cytokines, leading to the disregulation of cardiac ANF and BNP production observed during myocardial inflammation, and that this process is angiotensin receptor 1 dependent.

Inflammation in chronic heart failure

OBJECTIVE

To summarize findings regarding the association of inflammatory processes with chronic heart failure (HF).

DATA SOURCES

We conducted PubMed/MEDLINE searches (1966-January 2008) of primary literature using the following key words: ACE inhibitors, allopurinol, angiotensin-receptor antagonists, cardiomyopathy, chemokines, cytokines, diuretics, heart failure, inflammation, interleukins, HMG-CoA reductase inhibitors, immunotherapy, medications used in heart failure, thalidomide, tumor necrosis factor, and uric acid.

STUDY SELECTION AND DATA EXTRACTION

All articles that appeared to be relevant were read; of 305 articles examined, 87 were selected for discussion. Articles were selected if they were written in English and focused on any of the key words or appeared to have substantial content addressing inflammation in HF.

DATA SYNTHESIS

Cytokines, uric acid, and other inflammatory mediators are associated with physiologic effects that are also prominent features of HF (eg, reduced contractility and cardiac output, endothelial dysfunction, hypercoagulability, autonomic dysfunction as evidenced by reduced resting heart rate variability, insulin resistance). With the exception of elevated tumor necrosis factor-alpha as a cause of insulin resistance, it is not clear whether elevated inflammatory mediators directly cause HF signs and symptoms or whether they are incidental markers. Awareness of these associations has occurred relatively recently; there have been few clinical studies of efforts to directly modify inflammatory mediators. Most currently accepted drug therapies of HF reduce concentrations of circulating cytokines, but the significance of these findings awaits directed study.

CONCLUSIONS

Loss of myocardial function, autonomic dysfunction, and glucose intolerance are interrelated and linked by underlying chronic low-grade inflammation. Drug therapy with statins, pentoxifylline, and perhaps urate-lowering agents, in addition to current therapies, holds promise for treatment of HF.