Marcia Kiyomi Koike

Bradykinin B2 receptor antagonism attenuates inflammation, mast cell infiltration and fibrosis in remote myocardium after infarction in rats

1. Bradykinin may interfere with myocardial remodelling by promoting inflammation and mast cell activation or, alternatively, by counteracting angiotensin II‐dependent collagen accumulation. The aim of the present study was to investigate the role of bradykinin B2 receptor antagonism in inflammatory and mast cell infiltration, fibroplasia and fibrosis accumulation following myocardial infarction (MI).

Low coronary driving pressure early in the course of myocardial infarction is associated with subendocardial remodelling and left ventricular dysfunction

Subendocardial remodelling of the left ventricular (LV) non‐infarcted myocardium has been poorly investigated. Previously, we have demonstrated that low coronary driving pressure (CDP) early postinfarction was associated with the subsequent development of remote subendocardial fibrosis. The present study aimed at examining the role of CDP in LV remodelling and function following infarction. Haemodynamics were performed in Wistar rats immediately after myocardial infarction (MI group) or sham surgery (SH group) and at days 1, 3, 7 and 28. Heart tissue sections were stained with HE, Sirius red and immunostained for α‐actin. Two distinct LV regions remote to infarction were examined: subendocardium (SE) and interstitium (INT). Myocyte necrosis, leucocyte infiltration, myofibroblasts and collagen volume fraction were determined. Compared with SH, MI showed lower CDP and LV systolic and diastolic dysfunction. Necrosis was evident in SE at day 1. Inflammation and fibroplasia predominated in SE as far as day 7. Fibrosis was restricted to SE from day 3 on. Inflammation occurred in INT at days 1 and 3, but at a lower grade than in SE. CDP correlated inversely with SE necrosis (r = −0.65, P = 0.003, at day 1), inflammation (r = −0.76, P < 0.001, at day 1), fibroplasia (r = −0.47, P = 0.04, at day 7) and fibrosis (r = −0.83, P < 0.001, at day 28). Low CDP produced progressive LV expansion. Necrosis at day 1, inflammation at days 3 and 7, and fibroplasia at day 7 correlated inversely with LV function. CDP is a key factor to SE integrity and affects LV remodelling and function following infarction.

Dietary interesterified fat enriched with palmitic acid induces atherosclerosis by impairing macrophage cholesterol efflux and eliciting inflammation

Interesterified fats are currently being used to replace trans fatty acids. However, their impact on biological pathways involved in the atherosclerosis development was not investigated. Weaning male LDLr-KO mice were fed for 16weeks on a high-fat diet (40% energy as fat) containing polyunsaturated (PUFA), TRANS, palmitic (PALM), palmitic interesterified (PALM INTER), stearic (STEAR) or stearic interesterified (STEAR INTER). Plasma lipids, lipoprotein profile, arterial lesion area, macrophage infiltration, collagen content and inflammatory response modulation were determined. Macrophage cholesterol efflux and the arterial expression of cholesterol uptake and efflux receptors were also performed. The interesterification process did not alter plasma lipid concentrations. Although PALM INTER did not increase plasma cholesterol concentration as much as TRANS, the cholesterol enrichment in the LDL particle was similar in both groups. Moreover, PALM INTER induced the highest IL-1β, MCP-1 and IL-6 secretion from peritoneal macrophages as compared to others. This inflammatory response elicited by PALM INTER was confirmed in arterial wall, as compared to PALM. These deleterious effects of PALM INTER culminate in higher atherosclerotic lesion, macrophage infiltration and collagen content than PALM, STEAR, STEAR INTER and PUFA. These events can partially be attributed to a macrophage cholesterol accumulation, promoted by apoAI and HDL2-mediated cholesterol efflux impairment and increased Olr-1 and decreased Abca1 and Nr1h3 expressions in the arterial wall. Interesterified fats containing palmitic acid induce atherosclerosis development by promoting cholesterol accumulation in LDL particles and macrophagic cells, activating the inflammatory process in LDLr-KO mice.

The long-term outcome of patients with hypertensive cardiomyopathy

The prognosis of dilated cardiomyopathy due to hypertension (HT-DCM) is surprisingly unknown, particularly in the absence of coronary disease and diabetes. We aimed at investigating the long-term outcome and the predictors of mortality in patients with left ventricular systolic dysfunction exclusively due to hypertension. From October 1995 to May 2001, 90 consecutive patients with echocardiographic fractional shortening (FS) <30% and 29 control patients with FS ⩾30% were included. Obstructive coronary disease was excluded by dipyridamole myocardial perfusion imaging in all patients and coronary angiography in 60. After a mean follow-up of 4.3±1.6 years, the total mortality rate of HT-DCM was twice as much higher than that of patients without left ventricular systolic dysfunction (P=0.01). In HT-DCM, the 5-year mortality rate was 26%. Univariate analyses selected age and creatinine for being positively related to mortality, and body mass index, FS and blood pressure during follow-up for being negatively related to mortality. Neither the improvement of left ventricular FS nor the decrease in left ventricular mass index was related to survival. Multivariate analysis identified (hazard ratio; 95% confidence interval) age (1.08; 1.02–1.13), body mass index (0.86; 0.75–0.98), and baseline FS (0.88; 0.78–0.98) as independent predictors of mortality. In conclusion, poor survival in HT-DCM can be anticipated by the severity of left ventricular systolic dysfunction and advanced age. Instead of ominous signs, high blood pressure and body mass may predict a more favourable prognosis.

Increased intestinal production of α-defensins in aged rats with acute pancreatic injury

Acute pancreatitis is a life-threatening situation, frequently associated with uncontrolled local and systemic inflammation, and aging is associated with a worst prognosis. Antimicrobial peptides are ancient molecules that belong to innate immunity, produced by epithelial and immune cells, and are able to trigger a myriad of effector responses. We have hypothesized that antimicrobial peptides could play an important role during serious pancreatic injury. To investigate our hypothesis, α-defensin-5, α-defensin-7 and CRAMP gene expression levels were measured in the intestinal tissue of old and young rats submitted to chemical pancreatic damage. We found significantly higher levels of α-defensin-5 and α-defensin-7, but not CRAMP, in the samples from old mice. This increase was not associated with a worse systemic inflammatory response. We conclude that α-defensins may have a pivotal role during acute pancreatitis and that the elderly develops a more severe local, but not systemic inflammatory process.

Neuropeptides in the brain defense against distant organ damage

Delirium, or acute confusional state, is a common manifestation in diseases that originate outside the central nervous system, affecting 30-40% of elderly hospitalized patients and up to 80% of the critically ill, even though it remains unclear if severe systemic inflammation is able or not to induce cellular disturbances and immune activation in the brain. Neuropeptides are pleotropic molecules heterogeneously distributed throughout the brain and possess a wide spectrum of functions, including regulation of the inflammatory response, so we hypothesized that they would be the major alarm system in the brain before overt microglia activation. In order to investigate this hypothesis, we induced acute pancreatitis in 8-10week old rats and collected brain tissue, 12 and 24h following pancreatic injury, to measure neuropeptide and cytokine tissue levels. We found significantly higher levels of β-endorphin, orexin and oxytocin in the brain of rats submitted to pancreatic injury, when compared to healthy controls. Interestingly, these differences were not associated with increased local cytokine levels, putting in evidence that neuropeptide release occurred independently of microglia activation and may be a pivotal alarm system to initiate neurologic reactions to distant inflammatory non-infectious aggression.

Intestinal barrier dysfunction and increased COX-2 gene expression in the gut of elderly rats with acute pancreatitis.

BACKGROUND/OBJECTIVES The clinical course of acute pancreatitis can vary from mild to severe. In its most severe manifestation, acute pancreatitis is associated with an exacerbated systemic inflammatory response and high mortality rates. The severe form of acute pancreatitis is more frequent in elderly patients than in young patients, but the mechanisms underlying this difference are still under investigation. METHODS Rats were divided into two groups as follows: Group 1, young rats; and Group 2, old rats. Acute pancreatitis group was induced by a retrograde injection of a sodium taurocholate solution into the biliopancreatic duct. Using this model of acute pancreatic injury, we designed a study to investigate possible differences in microbial translocation and characteristics of the intestinal barrier between elderly and young rats. RESULTS There was a significantly higher number of bacterial colonies in the pancreas of elderly rats compared with young rats following pancreas injury, which was associated with a more severe local intestinal inflammatory response that included elevated gene expression of COX-2 and a decreased gene expression of tight junction proteins. CONCLUSIONS We conclude that intestinal damage during acute pancreatitis is exacerbated in elderly rats compared with young rats and that COX-2 inhibition could be a potential therapeutic target to offer tailored treatment for acute pancreatitis in the elderly.

Ischemic preconditioning attenuates remote pulmonary inflammatory infiltration of diabetic rats with an intestinal and hepatic ischemia-reperfusion injury

PURPOSE To assess ischemic preconditioning (IPC) effects in pulmonary lesion in intestinal and hepatic ischemia-reperfusion (IR) injury models using diabetic rats. METHODS Diabetes (DM) was induced in 28 male Wistar rats by alloxan (42 mg/kg, IV). After 28 days, severe DM rats were submitted to intestinal or hepatic IR injury with or without IPC. Intestinal IR (30 min of mesenteric artery occlusion and 30 min of reperfusion; n=6) and IPC groups (10 min ischemia, 10 min reperfusion, followed by intestinal IR; n=6), and Hepatic IR (30 min of hepatic pedicle occlusion and 30 min of reperfusion; n=5) and IPC groups (10 min ischemia, 10 min reperfusion, followed by hepatic IR; n=5), were compared to DM rats group (n=6). Plasmatic lactate, glycemia were measured before and after IR injury. Histomorphology of lung was performed counting inflammatory cells. Data was expressed in mean± SE. P<0.05. RESULTS Glycemia and lactate were similar among groups. IPC did not interfere in these parameters. On histological evaluation, IR increased inflammatory cells infiltration in pulmonary parenchyma compared to control in both IR injury models. IPC attenuated inflammatory infiltration in lungs. CONCLUSION Ischemic preconditioning protects against remote ischemia-reperfusion injury in lung on intestinal or hepatic ischemia-reperfusion model with acute diabetes.

Subendocardial fibrosis in remote myocardium results from reduction of coronary driving pressure during acute infarction in rats

OBJECTIVE To investigate the role of hemodynamic changes occurring during acute MI in subsequent fibrosis deposition within non-MI. METHODS By using the rat model of MI, 3 groups of 7 rats each [sham, SMI (MI <30%), and LMI (MI >30%)] were compared. Systemic and left ventricular (LV) hemodynamics were recorded 10 minutes before and after coronary artery ligature. Collagen volume fraction (CVF) was calculated in picrosirius red-stained heart tissue sections 4 weeks later. RESULTS Before surgery, all hemodynamic variables were comparable among groups. After surgery, LV end-diastolic pressure increased and coronary driving pressure decreased significantly in the LMI compared with the sham group. LV dP/dt max and dP/dt min of both the SMI and LMI groups were statistically different from those of the sham group. CVF within non-MI interventricular septum and right ventricle did not differ between each MI group and the sham group. Otherwise, subendocardial (SE) CVF was statistically greater in the LMI group. SE CVF correlated negatively with post-MI systemic blood pressure and coronary driving pressure, and positively with post-MI LV dP/dt min. Stepwise regression analysis identified post-MI coronary driving pressure as an independent predictor of SE CVF. CONCLUSION LV remodeling in rats with MI is characterized by predominant SE collagen deposition in non-MI and results from a reduction in myocardial perfusion pressure occurring early on in the setting of MI.

Heart injury following intestinal ischemia reperfusion in rats is attenuated by association of ischemic preconditioning and adenosine

PURPOSE To investigate the effect of ischemic preconditioning (IPC) and adenosine as strategies to protect cardiac injury caused by intestinal IR in rats, based on increasing in adenosine bioavailability and improvement of cell energy state by IPC. METHODS Male Wistar rats were submitted to 60 minutes of intestinal ischemia and 120 minutes of reperfusion. Intravenous injections of saline or Adenosine (AD) was administered five minutes before ischemia, five minutes before reperfusion and after 55 minutes reperfusion. Cardiac samples were obtained, fixed in formalin solution, embedded in paraffin, and sections of 5 μm were stained by hematoxylin-eosin. Histological analysis of myocardium was performed according occurrence of necrosis signs: piknosis, band contraction, eosinophilic cytoplasm, karyorrhexis and vacuolization (score - zero to 5). RESULTS The groups submitted to ischemia alone (I=4.0), and reperfusion (IR=4.5) showed highest level of lesion compared to the others (I+IPC=3.3, IR+IPC=3.6, I+AD=3.0, IR+AD=3.8). The most interesting result was association of IPC and AD in IR model (IR+IPC+AD=1.2, p=0.002), showing preservation of the heart tissue, with fibers showing typical cross-striations and nuclei characteristics. Rare and small areas of tissue necrosis was observed and suggestion of capillaries congestion. CONCLUSION Intestinal ischemia reperfusion promotes cardiac tissue injury. Ischemic preconditioning in association with adenosine is an efficient strategy to protect the heart against ischemia and reperfusion injury.