Shuchita Tiwari

The Heme Oxygenase System Selectively Enhances the Anti-Inflammatory Macrophage-M2 Phenotype, Reduces Pericardial Adiposity, and Ameliorated Cardiac Injury in Diabetic Cardiomyopathy in Zucker Diabetic Fatty Rats

Cardiac function is adversely affected by pericardial adiposity. We investigated the effects of the heme oxygenase (HO) inducer, hemin on pericardial adiposity, macrophage polarization, and diabetic cardiopathy in Zucker diabetic fatty rats (ZDFs) with use of echocardiographic, quantitative real-time polymerase chain reaction, Western immunoblotting, enzyme immunoassay, and spectrophotometric analysis. In ZDFs, hemin administration increased HO activity; normalized glycemia; potentiated insulin signaling by enhancing insulin receptor substrate 1(IRS-1), phosphatidylinositol-3-kinase (PI3K), and protein kinase B (PKB)/Akt; suppressed pericardial adiposity, cardiac hypertrophy, and left ventricular longitudinal muscle fiber thickness, a pathophysiological feature of cardiomyocyte hypertrophy; and correspondingly reduced systolic blood pressure, total peripheral resistance, and pro-inflammatory/oxidative mediators, including nuclear factor κB (NF-κB), cJNK, c-Jun-N-terminal kinase (cJNK), endothelin (ET-1), tumor necrosis factor α (TNF-α), interleukin (IL)–6, IL-1β, activating protein 1 (AP-1), and 8-isoprostane, whereas the HO inhibitor, stannous mesoporphyrin, nullified the effects. Furthermore, hemin reduced the pro-inflammatory macrophage M1 phenotype, but enhanced the M2 phenotype that dampens inflammation. Because NF-κB activates TNFα, IL-6, and IL-1β and TNF-α, cJNK, and AP-1 impair insulin signaling, the high levels of these cytokines in obesity/diabetes would create a vicious cycle that, together with 8-isoprostane and ET-1, exacerbates cardiac injury, compromising cardiac function. Therefore, the concomitant reduction of pro-inflammatory cytokines and macrophage infiltration coupled to increased expressions of IRS-1, PI3K, and PKB may account for enhanced glucose metabolism and amelioration of cardiac injury and function in diabetic cardiomyopathy. The hemin-induced preferential polarization of macrophages toward anti-inflammatory macrophage M2 phenotype in cardiac tissue with concomitant suppression of pericardial adiposity in ZDFs are novel findings. These data unveil the benefits of hemin against pericardial adiposity, impaired insulin signaling, and diabetic cardiomyopathy and suggest that its multifaceted protective mechanisms include the suppression of inflammatory/oxidative mediators.

Intensive resistance exercise induces lymphocyte apoptosis via cortisol and glucocorticoid receptor-dependent pathways

Intensive endurance exercise is known to induce lymphocyte apoptosis, which might affect immune function. Less is known about the effects of resistance exercise on apoptosis and its underlying mechanisms. In this study, subjects performed an intensive resistance test (IRT) and a moderate resistance test, and lymphocyte apoptosis, apoptosis-related parameters, and underlying mechanisms were investigated. IRT induced a significant increase of lymphocyte apoptosis 3 h after exercise, which was accompanied by a significant decrease of mitochondrial membrane potential, a reduction of Bcl-2, and an upregulation of the CD95 receptor. Blood lactate, IL-6, C-reactive protein, and cortisol increased significantly 3 h after IRT. A significant correlation was observed between the increase of apoptosis and cortisol levels 3 h after IRT. Incubation of freshly isolated lymphocytes in IRT serum indicated an important role of serum correlates for apoptosis induction. Selective incubation of lymphocytes in concentrations of selected serum parameters corresponding to levels found post in IRT serum demonstrated a major role for cortisol in apoptosis induction. This result was confirmed by attenutation of apoptosis after addition of mifepristone before incubation in IRT serum. In summary, resistance exercise induced lymphocyte apoptosis in an intensity-dependent way. Furthermore, cortisol signaling via glucocorticoid receptors might be an important mechanism for lymphocyte apoptosis after resistance exercise.

The Heme Oxygenase System and Type-1 Diabetes

Diabetes is a complex endocrine/metabolic disease with many related complications including micro-vascular and macrovascular problems such as cardiomyopathy, nephropathy, neuropathy and retinopathy. Generally, type-1 diabetes is caused by autoimmune- mediated destruction of pancreatic beta cells leading to insulin deficiency. This is usually accompanied by dyslipidemia, enhanced hyperglycemia-mediated oxidative stress, endothelial-cell dysfunction and apoptosis. For decades, type-1 diabetes has been traditionally known as insulin-dependent, while type-2 as non-insulin dependent diabetes. However, it is becoming increasingly clear that insulin deficiency and insulin resistance are manifested in both forms of diabetes at different stages. Thus, it may be time revisit the nomenclature and adjust it to reflect these observations of insulin deficiency and insulin resistance in both forms of diabetes to avoid ambiguity when discussing forms of diabetes. Emerging evidence indicates that the heme-oxygenase (HO) system and related products including carbon monoxide, ferritin and biliverdin are capable of suppressing immune/inflammatory response, and abate oxidative stress and apoptosis. More importantly, upregulating the HO-system increases pancreatic beta-cell insulin release and reduce hyperglycemia in different diabetic models. Similarly, carbon monoxide, a product of the HO-catalyzed degradation of heme also enhances insulin production and improves glucose metabolism. Since excessive immune/inflammatory responses coupled to elevated apoptosis are among the cardinal pathophysiological features of type-1 diabetes, this review highlights the role of the HO-system and related products such as carbon monoxide and bilirubin in the modulation of apoptosis and immune response, and the beneficial effects of the HO-system in the pathogenesis of type-1 diabetes and related cardiometabolic complications.

The Role of Obesity in Cardiomyopathy and Nephropathy

The growing incidence of obesity and related complications such as cardiomyopathy and nephropathy remains a global health challenge. Many pathophysiological factors including inflammation, oxidative stress and endothelial dysfunction are implicated in obesity- induced abnormalities in the heart and kidney. Moreover, obesity and nutrient-overload are associated with the activation of different inflammatory/oxidative signaling pathways such as endoplasmic reticulum stress, nuclear factor-kappaB (NF-κB), toll-like-receptor-4 (TLR4) and the renin-angiotensin-aldosterone system (RAAS). The pathophysiological role of RAAS, TLR4 and NF-κB in perturbing physiological milieu is well acknowledged. Several pharmacological agents have been formulated to target one or more of these pathways. Although significant strides have been made in elucidating mechanisms implicated in obesity-related cardio-renal diseases, much still has to be done. The pathophysiology of cardiomyopathy and nephropathy is complex and multifaceted. Besides NF-κ B, TLR4, RAAS and inflammatory mediators such as cytokines and chemokines, a wide spectrum of different factors including, the environment, diets, lifestyles, genetics and epigenetics are also involved. With such multifactorial etiology, it remains a daunting challenge to identify the factor(s) that initiate the activation and propagation of adverse stimuli that eventually lead to cardiomyopathy and/or nephropathy in obese individuals. Similarly, the mechanisms of such activation and propagation should be clearly elucidated. Should these hurdles be overcome, there would be a greater likelihood for the development of more-effective therapeutic strategies for the prevention, treatment and management of obesity-induced cardiomyopathy and nephropathy. The present review examines the role of inflammation, oxidative stress and endothelial dysfunction in obesity-induced abnormalities in heart and kidney.

The Heme Oxygenase System Rescues Hepatic Deterioration in the Condition of Obesity Co-Morbid with Type-2 Diabetes

The prevalence of non-alcoholic fatty-liver disease (NAFLD) is increasing globally. NAFLD is a spectrum of related liver diseases that progressive from simple steatosis to serious complications like cirrhosis. The major pathophysiological driving of NAFLD includes elevated hepatic adiposity, increased hepatic triglycerides/cholesterol, excessive hepatic inflammation, and hepatocyte ballooning injury is a common histo-pathological denominator. Although heme-oxygenase (HO) is cytoprotective, its effects on hepatocyte ballooning injury have not been reported. We investigated the effects of upregulating HO with hemin or inhibiting it with stannous-mesoporphyrin (SnMP) on hepatocyte ballooning injury, hepatic adiposity and inflammation in Zucker-diabetic-fatty rats (ZDFs), an obese type-2-diabetic model. Hemin administration to ZDFs abated hepatic/plasma triglycerides and cholesterol, and suppressed several pro-inflammatory cytokines and chemokines including, TNF-α, IL-6, IL-1β, macrophage-inflammatory-protein-1α (MIP-1α) and macrophage-chemoattractant-protein-1 (MCP-1), with corresponding reduction of the pro-inflammatory M1-phenotype marker, ED1 and hepatic macrophage infiltration. Correspondingly, hemin concomitantly potentiated the protein expression of several markers of the anti-inflammatory macrophage-M2-phenotype including ED2, IL-10 and CD-206, alongside components of the HO-system including HO-1, HO-activity and cGMP, whereas the HO-inhibitor, SnMP abolished the effects. Furthermore, hemin attenuated liver histo-pathological lesions like hepatocyte ballooning injury and fibrosis, and reduced extracellular-matrix/profibrotic proteins implicated in liver injury such as osteopontin, TGF-β1, fibronectin and collagen-IV. We conclude that hemin restore hepatic morphology by abating hepatic adiposity, suppressing macrophage infiltration, inflammation and fibrosis. The selective enhancement of anti-inflammatory macrophage-M2-phenotype with parallel reduction of pro-inflammatory macrophage-M1-phenotype and related chemokines/cytokines like TNF-α, IL-6, IL-1β, MIP-1α and MCP-1 are among the multifaceted mechanisms by which hemin restore hepatic morphology.

Therapeutic Interventions for Advanced Glycation-End Products and its Receptor- Mediated Cardiovascular Disease

Advanced glycation end products (AGEs) are heterogeneous group of molecules formed from nonenzymatic reaction of reducing sugars with amino group of proteins, lipids, and nucleic acid. Interaction of AGEs with its cell-bound receptor (RAGE) results in generation of oxygen radicals, nuclear factor kappa-β, proinflammatory cytokines and cell adhesion molecules, and is involved in the pathophysiology of cardiovascular diseases (CVD). Circulating soluble forms of RAGE (sRAGE) and endo-secretory RAGE (esRAGE) compete with RAGE for ligand binding and function as a decoy. This paper describes the endogenous and exogenous (high dietary AGEs, and cooking food under high dry heat, elevated pH, and longer period) sources of AGEs. AGERAGE- mediated CVD includes atherosclerosis, coronary artery disease, carotid artery disease, hypertension, peripheral vascular diseases, heart failure, cardiomyopathy, and microangiopathy. The therapeutic interventions with reduction in AGEs and RAGE, and elevation in sRAGE has been reported for the treatment of AGE-RAGEmediated CVD. Reduction in levels of AGEs can be achieved by reduction in consumption of food containing low amount of AGEs, cooking food at low temperature, moist heat, and shorter duration. AGE formation can be reduced with drugs, vitamins and stoppage of cigarette smoking. Statins, telmisartan, and curcumin have been used for suppression of RAGE. Statins, ACE-inhibitors, Rosiglitazone and vitamin D have been used to increase levels of sRAGE. Finally exogenous administration of sRAGE can be helpful in amelioration of CVD. In conclusion, AGE-RAGE-mediated CVD could be attenuated with reduction in consumption of AGEs, suppression of RAGE and elevation of sRAGE.

Heme oxygenase system and hypertension: a comprehensive insight.

Hypertension is a complex interplay of interrelated etiologies, and the leading risk factor for many cardiovascular morbidity and mortality worldwide. Cardinal pathophysiological features of hypertension include enhanced vascular inflammation, vascular remodeling, vascular contractility and increased oxidative stress. In response to oxidative, inflammatory or other noxious stimuli, many physiological pathways like the heme oxygenase (HO) system are activated in an attempt to counteract tissue insults. However, the pathophysiological activation of the HO system only results to a transient increase of HO activity that fall below the necessary threshold capable of activating the downstream signaling components of the HO system like the soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP) secondary messenger system. Therefore, a more robust potentiation of the HO system by pharmacological agents such as hemin, heme-arginate, cobalt protoporphyrin or through retroviral HO-1 gene delivery would be needed to surmount the threshold for cytoprotection. The HO system modulates cellular homeostasis. Importantly, the HO system plays a vital role in a wide spectrum of physiologic including the regulation of blood vessel tone. Alterations in the activity and expression of HO has been correlated to pathophysiology of hypertension and related complications such as hypertrophy, myocardial infarction and heart failure. Moreover, the cytoprotection exerted by HO is attributable to its catabolic products namely, carbon monoxide, bilirubin/biliverdin, and ferritin that are known to modulate immune, inflammatory and oxidative insults. The growing incidence of hypertension and associated cardiometabolic complications has prompted the need for the exploration of alternative therapeutic strategies like substances capable of potentiating the HO system. This review briefly, highlights the functional significance of the HO system and its downstream signaling molecules including bilirubin/biliverdin, carbon monoxide and ferritin as potential therapeutic modalities for the management of hypertension and its related co-morbid conditions.

Mechanisms by which heme oxygenase rescue renal dysfunction in obesity.

Obesity and excessive inflammation/oxidative stress are pathophysiological forces associated with kidney dysfunction. Although we recently showed that heme-oxygenase (HO) improves renal functions, the mechanisms are largely unclear. Moreover, the effects of the HO-system on podocyte cytoskeletal proteins like podocin, podocalyxin, CD2-associated-protein (CD2AP) and proteins of regeneration/repair like beta-catenin, Oct3/4, WT1 and Pax2 in renal tissue from normoglycemic obese Zucker-fatty rats (ZFs) have not been reported. Treatment with hemin reduced renal histo-pathological lesions including glomerular-hypertrophy, tubular-cast, tubular-atrophy and mononuclear cell-infiltration in ZFs. These were associated with enhanced expression of beta-catenin, Oct3/4, WT1, Pax2 and nephrin, an essential transmembrane protein required for the formation of the scaffoldings of the podocyte slit-diaphragm, permitting the filtration of small ions, but not massive excretion of proteins, hence proteinuria. Besides nephrin, hemin also enhanced other important podocyte-regulators including, podocalyxin, podocin and CD2AP. Correspondingly, important markers of renal dysfunction such as albuminuria and proteinuria were reduced, while creatinine clearance increased, suggesting improved renal function in hemin-treated ZFs. The renoprotection by hemin was accompanied by the reduction of inflammatory/oxidative mediators including, macrophage-inflammatory-protein-1α, macrophage-chemoattractant-protein-1 and 8-isoprostane, whereas HO-1, HO-activity and the total-anti-oxidant-capacity increased. Contrarily, the HO-inhibitor, stannous-mesoporphyrin nullified the reno-protection by hemin. Collectively, these data suggest that hemin ameliorates nephropathy by potentiating the expression of proteins of repair/regeneration, abating oxidative/inflammatory mediators, reducing renal histo-pathological lesions, while enhancing nephrin, podocin, podocalyxin, CD2AP and creatinine clearance, with corresponding reduction of albuminuria/proteinuria suggesting improved renal function in hemin-treated ZFs. Importantly, the concomitant potentiation regeneration proteins and podocyte cytoskeletal proteins are novel mechanisms by which hemin rescue nephropathy in obesity.

Featured article: induction of heme oxygenase with hemin improves pericardial adipocyte morphology and function in obese Zucker rats by enhancing proteins of regeneration.

Oxidative stress and inflammation are implicated in tissue remodeling, hypertrophy, and organ malfunction. Since heme-oxygenase (HO) is a cytoprotective enzyme with effects against oxidative stress and inflammation, we investigated the effects of upregulating HO with hemin on adipocyte hypertrophy, proteins of repair/regeneration including beta-catenin, Oct3/4 and Pax2 as well as pro-fibrotic/remodeling proteins like osteopontin and transforming growth factor-beta (TGF-β) in pericardial adipose tissue from obese Zucker rats (ZRs). Treatment with hemin significantly reduced pericardial adipose tissue inflammation/oxidative stress, suppressed osteopontin and TGF-β, and attenuated pericardial adipocyte hypertrophy in obese ZRs. These were associated with enhanced expression of the stem/progenitor-cell marker cKit; the potentiation of several proteins of regeneration including beta-catenin, Oct3/4, Pax2; and improved pericardial adipocyte morphology. Interestingly, the amelioration of adipocyte hypertrophy in hemin-treated animals was accompanied by improved adipocyte function, evidenced by increased levels of pericardial adipose tissue adiponectin. Furthermore, hemin significantly reduced hypertriglyceridemia and hypercholesteromia in obese ZRs. The protective effects of hemin were accompanied by robust potentiation HO activity and the total antioxidant capacity, whereas the co-administration of hemin with the HO inhibitor, stannous mesoporphyrin abolished the effects of hemin. These data suggest that hemin improves pericardial adipocyte morphology and function by enhancing proteins of repair and regeneration, while concomitantly abating inflammatory/oxidative insults and suppressing extracellular-matrix/profibrotic and remodeling proteins. The reduction of hypertriglyceridemia, hypercholesteromia, pericardial adiposity, and pericardial adipocyte hypertrophy with corresponding improvement of adipocyte morphology/function in hemin-treated animals suggests that HO inducers may be explored for the design of novel remedies against cardiac complications arising from excessive adiposity.

The Risk of Heart Failure and Cardiometabolic Complications in Obesity May Be Masked by an Apparent Healthy Status of Normal Blood Glucose

Although many obese individuals are normoglycemic and asymptomatic of cardiometabolic complications, this apparent healthy state may be a misnomer. Since heart failure is a major cause of mortality in obesity, we investigated the effects of heme-oxygenase (HO) on heart failure and cardiometabolic complications in obese normoglycemic Zucker-fatty rats (ZFs). Treatment with the HO-inducer, hemin, reduced markers of heart failure, such as osteopontin and osteoprotegerin, abated left-ventricular (LV) hypertrophy/fibrosis, extracellular matrix/profibrotic proteins including collagen IV, fibronectin, TGF-β1, and reduced cardiac lesions. Furthermore, hemin suppressed inflammation by abating macrophage chemoattractant protein-1, macrophage-inflammatory protein-1 alpha, TNF-α, IL-6, and IL-1β but enhanced adiponectin, atrial-natriuretic peptide (ANP), HO activity, insulin sensitivity, and glucose metabolism. Correspondingly, hemin improved several hemodynamic/echocardiographic parameters including LV-diastolic wall thickness, LV-systolic wall thickness, mean-arterial pressure, arterial-systolic pressure, arterial-diastolic pressure, LV-developed pressure, +dP/dt, and cardiac output. Contrarily, the HO-inhibitor, stannous mesoporphyrin nullified the hemin effect, exacerbating inflammatory/oxidative insults and aggravated insulin resistance (HOMA-index). We conclude that perturbations in insulin signaling and cardiac function may be forerunners to overt hyperglycemia and heart failure in obesity. Importantly, hemin improves cardiac function by suppressing markers of heart failure, LV hypertrophy, cardiac lesions, extracellular matrix/profibrotic proteins, and inflammatory/oxidative mediators, while concomitantly enhancing the HO-adiponectin-ANP axis.