β2 Adrenergic Regulation of the Phagocytic and Microbicide Capacity of Macrophages from Obese and Lean Mice: Effects of Exercise

The β2-adrenergic receptor agonist formoterol attenuates necrosis and apoptosis in the rat myocardium under experimental stress-induced cardiac injury

BACKGROUND

Currently, there is no effective therapy for takotsubo syndrome (stress-induced cardiac injury in humans) in the clinics. It has previously been shown that β2-adrenergic receptor (β2-AR) agonist formoterol reduces cardiomyocyte injury in experimental takotsubo syndrome.

OBJECTIVES

The aim of this study was to investigate whether formoterol prevents apoptosis and necrosis of cardiomyocytes and endothelial cells in stress-induced cardiomyopathy.

METHODS

Stress-induced cardiac injury was induced by immobilization of rats for 2, 6, and 24 hours.

RESULTS

The myocardium of stressed rats showed a reduction in contractility and histological manifestations of cardiomyocyte damage: karyopyknosis, perinuclear edema of cardiomyocytes and endothelial cells, and microcirculation disturbances augmented with extended exposure to stress. In addition, apoptosis of endothelial cells was detected 6 hours after the onset of stress and peaked at 24 hours. Apoptosis of cardiomyocytes significantly gained only after 24 hours of stress exposure. These morphological alterations were associated with increased levels of serum creatine kinase-MB, syndecan-1, and thrombomodulin after 24 hours of stress. Administration of β2-AR agonist formoterol (50 μg/kg) four times during 24-hour stress exposure led to the improvement in myocardial inotropy, decrease in the severity of histological signatures, reduction in the number of TUNEL-positive cardiomyocytes, serum creatine kinase-MB, syndecan-1, and thrombomodulin levels.

CONCLUSION

Present data suggest that apoptosis and necrosis of cardiomyocytes and necrosis of endothelial cells in stress-induced cardiac injury can be mitigated by activation of the β2-AR. However, formoterol did not eliminate completely cardiomyocyte apoptosis, histological alterations, or endothelium injury markers under stress.

Obesity-compromised immunity in post-COVID-19 condition: a critical control point of chronicity

Post-COVID-19 condition is recognized as a multifactorial disorder, with persistent presence of viral antigens, discordant immunity, delayed viral clearance, and chronic inflammation. Obesity has emerged as an independent risk factor for both SARS-CoV-2 infection and its subsequent sequelae. In this study, we aimed to predict the molecular mechanisms linking obesity and post-COVID-19 distress. Viral antigen-exposed adipose tissues display remarkable levels of viral receptors, facilitating viral entry, deposition, and chronic release of inflammatory mediators and cells in patients. Subsequently, obesity-associated inflammatory insults are predicted to disturb cellular and humoral immunity by triggering abnormal cell differentiation and lymphocyte exhaustion. In particular, the decline in SARS-CoV-2 antibody titers and T-cell exhaustion due to chronic inflammation may account for delayed virus clearance and persistent activation of inflammatory responses. Taken together, obesity-associated defective immunity is a critical control point of intervention against post-COVID-19 progression, particularly in subjects with chronic metabolic distress.

Exercise Cuts Both Ways with ROS in Remodifying Innate and Adaptive Responses: Rewiring the Redox Mechanism of the Immune System during Exercise

Nearly all cellular functions depend on redox reactions, including those of immune cells. However, how redox reactions are rearranged to induce an immune response to the entry of pathogens into the host is a complex process. Understanding this scenario will facilitate identification of the roles of specific types of reactive oxygen species (ROS) in the immune system. Although the detrimental effect of ROS could support the innate immune system, the adaptive immune system also requires a low level of ROS in order to stimulate various molecular functions. The requirements and functions of ROS vary in different cells, including immune cells. Thus, it is difficult to understand the specific ROS types and their targeting functions. Incomplete transfer of electrons to a specific target, along with failure of the antioxidant response, could result in oxidative-damage-related diseases, and oxidative damage is a common phenomenon in most immune disorders. Exercise is a noninvasive means of regulating ROS levels and antioxidant responses. Several studies have shown that exercise alone boosts immune functions independent of redox reactions. Here, we summarize how ROS target various signaling pathways of the immune system and its functions, along with the possible role of exercise in interfering with immune system signaling.

Exercise and Adipose Tissue Immunity: Outrunning Inflammation

Chronic inflammation is considered a precipitating factor and possibly an underlying cause of many noncommunicable diseases, including cardiovascular disease, metabolic diseases, and some cancers. Obesity, which manifests in more than 650 million people worldwide, is the most common chronic inflammatory condition, with visceral adiposity thought to be the major inflammatory hub that links obesity and chronic disease. Adipose tissue (AT) inflammation is triggered or heightened in large part by (1) accelerated immune cell recruitment, (2) reshaping of the AT stromal-immuno landscape (e.g., immune cells, endothelial cells, fibroblasts, adipocyte progenitors), and (3) perturbed AT immune cell function. Exercise, along with diet management, is a cornerstone in promoting weight loss and preventing weight regain. This review focuses on evidence that increased physical activity reduces AT inflammation caused by hypercaloric diets or genetic obesity. The precise cell types and mechanisms responsible for the therapeutic effects of exercise on AT inflammation remain poorly understood. This review summarizes what is known about obesity-induced AT inflammation and immunomodulation and highlights mechanisms by which aerobic exercise combats inflammation by remodeling the AT immune landscape. Furthermore, key areas are highlighted that require future exploration and novel discoveries into the burgeoning field of how the biology of exercise affects AT immunity.

Immune Response to SARS-CoV-2 Infection in Obesity and T2D: Literature Review

In December 2019, a novel coronavirus known as SARS-CoV-2 was first detected in Wuhan, China, causing outbreaks of the coronavirus disease COVID-19 that has now spread globally. For this reason, The World Health Organization (WHO) declared COVID-19 a public health emergency in March 2020. People living with pre-existing conditions such as obesity, cardiovascular diseases, type 2 diabetes (T2D), and chronic kidney and lung diseases, are prone to develop severe forms of disease with fatal outcomes. Metabolic diseases such as obesity and T2D alter the balance of innate and adaptive responses. Both diseases share common features characterized by augmented adiposity associated with a chronic systemic low-grade inflammation, senescence, immunoglobulin glycation, and abnormalities in the number and function of adaptive immune cells. In obese and T2D patients infected by SARS-CoV-2, where immune cells are already hampered, this response appears to be stronger. In this review, we describe the abnormalities of the immune system, and summarize clinical findings of COVID-19 patients with pre-existing conditions such as obesity and T2D as this group is at greater risk of suffering severe and fatal clinical outcomes.

Unilateral section of the superior ovarian nerve induces first ovulation in the Zucker fatty (fa/fa) rat

Hyperactivity in the sympathetic nervous system has been shown to be related to the development of ovarian pathologies. In addition, obesity has been found to be associated with multiple reproductive anomalies and is considered a chronic stress condition of low intensity with changes in the peripheral sympathetic activity. Therefore, in the present study, we aimed to evaluate if the information reaching the ovaries through the superior ovarian nerve (SON) modifies the ovarian function of Zucker fatty rats. We performed a unilateral section of the SON at 32 days of age and autopsies were carried out on the day of the first vaginal estrus. The results showed that fatty animals do not ovulate on the day of the first vaginal estrus and exhibit an increase in catecholaminergic fibers and the presence of precystic structures in the ovaries, without changes in the onset of puberty or in the secretion of ovarian and hypophyseal hormones. We also found that the section of the right SON resulted in ovulation on the day of the first vaginal estrus, which was accompanied by a decrease in ovarian noradrenaline content. The section of the left SON caused a delay in puberty without changes in the rest of the parameters. These results provide functional evidence that the peripheral sympathetic innervation participates in the regulation of ovarian functions in an animal model of genetic obesity.

Diet-induced rodent models of obesity-related metabolic disorders-A guide to a translational perspective

Diet is a critical element determining human health and diseases, and unbalanced food habits are major risk factors for the development of obesity and related metabolic disorders. Despite technological and pharmacological advances, as well as intensification of awareness campaigns, the prevalence of metabolic disorders worldwide is still increasing. Thus, novel therapeutic approaches with increased efficacy are urgently required, which often depends on cellular and molecular investigations using robust animal models. In the absence of perfect rodent models, those induced by excessive consumption of fat and sugars better replicate the key aspects that are the root causes of human metabolic diseases. However, the results obtained using these models cannot be directly compared, particularly because of the use of different dietary protocols, and animal species and strains, among other confounding factors. This review article revisits diet-induced models of obesity and related metabolic disorders, namely, metabolic syndrome, prediabetes, diabetes and nonalcoholic fatty liver disease. A critical analysis focused on the main pathophysiological features of rodent models, as opposed to the criteria defined for humans, is provided as a practical guide with a translational perspective for the establishment of animal models of obesity-related metabolic diseases.

Influence of Obesity and Exercise on β2-Adrenergic-Mediated Anti-Inflammatory Effects in Peritoneal Murine Macrophages

Obesity is a chronic low-grade inflammatory condition, and β2-adrenergic agonists as well as exercise have been proposed as anti-inflammatory strategies in obesity, so it is critical to accurately determine the effects of β2-adrenergic stimulation, especially when combined with other non-pharmacological therapies. The aim of this investigation was to determine the effect of β2-adrenergic activation on the inflammatory profile and phenotype of macrophages, and whether these effects could be affected by obesity and exercise in this condition. High-fat diet-induced obese and lean C57BL/6J mice were allocated to sedentary or exercised groups. The inflammatory profiles and phenotypes of their peritoneal macrophages were assessed by flow cytometry in the presence or absence of the selective β2-adrenergic receptor agonist terbutaline. β2-adrenergic activation caused global phenotypic anti-inflammatory effects in lean and obese sedentary mice, which were more drastic (also including anti-inflammatory effects on the cytokine profile) in obese animals. In exercised lean and obese animals, this anti-inflammatory effect is weaker and only evident by decreased iNOS and IL-8 expression, without changes in the anti-inflammatory markers. Therefore, β2-adrenergic activation leads to anti-inflammatory effects, but these effects are modulated by obesity in sedentary conditions, as well as by regular exercise; but not by obesity in trained conditions.

β2 Adrenergic Regulation of the Phagocytic and Microbicide Capacity of Circulating Monocytes: Influence of Obesity and Exercise

Obese individuals present anomalous immune/inflammatory responses with dysregulations in neuroendocrine responses and immune/stress feedback mechanisms. In this context, exercise and β2 adrenergic activation present monocyte-mediated anti-inflammatory effects that are modulated by obesity. However, these anti-inflammatory effects could immunocompromise the monocyte-mediated innate response against a pathogen challenge. Thus, the objective of this work was to evaluate the effect of obesity, and exercise in this condition, on the β2 adrenergic regulation of the phagocytic and microbicide capacity of circulating monocytes. C57BL/6J mice were allocated to different sedentary or exercised, lean or obese groups. Obese mice showed a lower monocyte-mediated innate response than that of lean mice. Globally, selective β2 adrenergic receptor agonist terbutaline decreased the innate response of monocytes from lean and obese sedentary animals, whereas exercise stimulated it. Exercise modulates β2 adrenergic regulation of the innate response in lean and obese animals, with a global stimulatory or neutral effect, thus abolishing the inhibitory effect of terbutaline occurring in sedentary animals. These effects cannot be explained only by changes in the surface expression of toll-like receptors. Therefore, in general, terbutaline does not hinder the effects of regular exercise, but regular exercise does abolish the effects of terbutaline in sedentary individuals.

Crescent-Like Lesions as an Early Signature of Nephropathy in a Rat Model of Prediabetes Induced by a Hypercaloric Diet

Diabetic nephropathy (DN) is a major microvascular complication of diabetes. Obesity and hyperlipidemia, fueled by unhealthy food habits, are risk factors to glomerular filtration rate (GFR) decline and DN progression. Several studies recommend that diabetic patients should be screened early (in prediabetes) for kidney disease, in order to prevent advanced stages, for whom the current interventions are clearly inefficient. This ambition greatly depends on the existence of accurate early biomarkers and novel molecular targets, which only may arise with a more thorough knowledge of disease pathophysiology. We used a rat model of prediabetes induced by 23 weeks of high-sugar/high-fat (HSuHF) diet to characterize the phenotype of early renal dysfunction and injury. When compared with the control animals, HSuHF-treated rats displayed a metabolic phenotype compatible with obese prediabetes, displaying impaired glucose tolerance and insulin sensitivity, along with hypertriglyceridemia, and lipid peroxidation. Despite unchanged creatinine levels, the prediabetic animals presented glomerular crescent-like lesions, accompanied by increased kidney Oil-Red-O staining, triglycerides content and mRNA expression of IL-6 and iNOS. This model of HSuHF-induced prediabetes can be a useful tool to study early features of DN, namely crescent-like lesions, an early signature that deserves in-depth elucidation.