Neutrophil-Mediated Cardiac Damage After Acute Myocardial Infarction: Significance of Defining a New Target Cell Type for Developing Cardioprotective Drugs
ANTIOXIDANTS & REDOX SIGNALING
Authors: El Kazzi, Mary; Rayner, Benjamin Saul; Chami, Belal; Dennis, Joanne Marie; Thomas, Shane Ross; Witting, Paul Kenneth
Abstract
Significance:Acute myocardial infarction (AMI) is a leading cause of death worldwide. Post-AMI survival rates have increased with the introduction of angioplasty as a primary coronary intervention. However, reperfusion after angioplasty represents a clinical paradox, restoring blood flow to the ischemic myocardium while simultaneously inducing ion and metabolic imbalances that stimulate immune cell recruitment and activation, mitochondrial dysfunction and damaging oxidant production. Recent Advances:Preclinical data indicate that these metabolic imbalances contribute to subsequent heart failure through sustaining local recruitment of inflammatory leukocytes and oxidative stress, cardiomyocyte death, and coronary microvascular disturbances, which enhance adverse cardiac remodeling. Both left ventricular dysfunction and heart failure are strongly linked to inflammation and immune cell recruitment to the damaged myocardium. Critical Issues:Overall, therapeutic anti-inflammatory and antioxidant agents identified in preclinical trials have failed in clinical trials. Future Directions:The versatile neutrophil-derived heme enzyme, myeloperoxidase (MPO), is gaining attention as an important oxidative mediator of reperfusion injury, vascular dysfunction, adverse ventricular remodeling, and atrial fibrillation. Accordingly, there is interest in therapeutically targeting neutrophils and MPO activity in the setting of heart failure. Herein, we discuss the role of post-AMI inflammation linked to myocardial damage and heart failure, describe previous trials targeting inflammation and oxidative stress post-AMI, highlight the potential adverse impact of neutrophil and MPO, and detail therapeutic options available to target MPO clinically in AMI patients.
Pretreatment of nafithromycin attenuates inflammatory response in murine lipopolysaccharide induced acute lung injury
CYTOKINE
Authors: Trivedi, Jinal; Shaikh, Javeed; Chavan, Nilesh; Thorve, Deepak; Chaudhary, Bhushan; Karade, Avinash; Gupta, Sangita; Patel, Anasuya; Bhagwat, Sachin
Abstract
Acute respiratory distress syndrome following an acute lung injury (ALI) is a life threatening inflammatory condition predominantly characterized by vascular protein leakage, neutrophil recruitment and overexpression of proinflammatory cytokines. Pulmonary and systemic bacterial infections are the major cause of ALI wherein the bacterial cell components play a crucial role. Macrolide/ketolide antibiotics are reported to possess immunomodulatory activity; as a result improved survival has been noted in pneumonia patients. Hence immunomodulatory activity of nafithromycin, a novel lactone ketolide antibacterial agent was assessed in the murine LPS induced ALI model. Vehicle, nafithromycin (100 mg/kg), azithromycin (600 mg/kg) and dexamethasone (20 mg/kg) were administered orally, 1 h prior to LPS challenge and bronchoalveolar lavage (BAL) fluid was collected thereafter at 18, 24 and 48 h to determine the total cell count, total protein, myeloperoxidase (MPO), tumor necrosis factor (TNF)-alpha and interleukin (IL)-6. Results from the current study showed that pretreatment with nafithromycin significantly reduced the total cell count, total protein, MPO, TNF-alpha and IL-6 levels in BAL fluid compared to LPS control group. Histopathological evaluations also suggest significant reduction in neutrophil infiltration by nafithromycin. Dexamethasone, a positive reference standard as expected exhibited potent anti-inflammatory activity. The immunomodulatory effect of nafithromycin at dose of 100 mg/kg was comparable to azithromycin dosed at 600 mg/kg. As a result of immunomodulatory activity, nafithromycin is expected to provide additional clinical benefits by resolving the secondary complications associated with severe pneumonia and thereby improving survival in such patients.