72 kDa Extracellular Heat Shock Protein (eHsp72), Norepinephrine (NE), and the Innate Immune Response Following Moderate Exercise. In: Asea AAA, Pedersen BK, editors. Heat Shock Proteins and Whole Body Physiology. Dordrecht: Springer Netherlands; 2010. pp. 327-50. [DOI: 10.1007/978-90-481-3381-9_19]

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.

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

Macrophages are crucial in the inflammation associated with obesity. Exercise is the main non-pharmacological strategy against obesity, not only for improving metabolic impairment, but also because of its anti-inflammatory effects, particularly those mediated by β2 adrenergic receptors (β2-AR). Nevertheless, these anti-inflammatory effects could immunocompromise the innate response against pathogen challenge. Thus, the objective of this work was to evaluate the effect of obesity, and of exercise in this condition, on the β2 adrenergic regulation of the innate function of macrophages. High fat diet-induced obese C57BL/6J mice were used to evaluate the effects of acute and regular exercise on the phagocytic and microbicide capacities of peritoneal macrophages. Selective β2-AR agonist terbutaline (1 µM) decreased the phagocytic and microbicide activities of macrophages from control lean and obese sedentary animals. While acute exercise did not modify the inhibitory capacity of terbutaline, regular exercise abolished this inhibitory effect. These effects cannot be explained only by changes in the surface expression of β2-AR. In conclusion, (1) obesity does not alter the β2-AR-mediated decrease of the innate response of macrophages and (2) regular exercise can revert the inhibitory effect of terbutaline on the phagocytic activity of macrophages, although obesity seems to hinder this immunophysiological adaptation.

Housing temperature influences the pattern of heat shock protein induction in mice following mild whole body hyperthermia

PURPOSE

Researchers studying the murine response to stress generally use mice housed under standard, nationally mandated conditions as controls. Few investigators are concerned whether basic physical aspects of mouse housing could be an additional source of stress, capable of influencing the subsequent impact of an experimentally applied stressor. We have recently become aware of the potential for housing conditions to impact important physiological and immunological properties in mice.

MATERIALS AND METHODS

Here we sought to determine whether housing mice at standard temperature (ST; 22 °C) vs. thermoneutral temperature (TT; 30 °C) influences baseline expression of heat shock proteins (HSPs) and their typical induction following a whole body heating.

RESULTS

There were no significant differences in baseline expression of HSPs at ST and TT. However, in several cases, the induction of Hsp70, Hsp110 and Hsp90 in tissues of mice maintained at ST was greater than at TT following 6 h of heating (which elevated core body temperature to 39.5 °C). This loss of HSP induction was also seen when mice housed at ST were treated with propranolol, a β-adrenergic receptor antagonist, used clinically to treat hypertension and stress.

CONCLUSIONS

Taken together, these data show that housing temperature significantly influences the expression of HSPs in mice after whole body heating and thus should be considered when stress responses are studied in mice.

Fibromyalgia: anti-inflammatory and stress responses after acute moderate exercise

Fibromyalgia (FM) is characterized in part by an elevated inflammatory status, and "modified exercise" is currently proposed as being a good therapeutic help for these patients. However, the mechanisms involved in the exercise-induced benefits are still poorly understood. The objective was to evaluate the effect of a single bout of moderate cycling (45 min at 55% VO2 max) on the inflammatory (serum IL-8; chemotaxis and O2 (-) production by neutrophils; and IL-1β, TNF-α, IL-6, IL-10, and IL-18 release by monocytes) and stress (cortisol; NA; and eHsp72) responses in women diagnosed with FM compared with an aged-matched control group of healthy women (HW). IL-8, NA, and eHsp72 were determined by ELISA. Cytokines released by monocytes were determined by Bio-Plex® system (LUMINEX). Cortisol was determined by electrochemoluminiscence, chemotaxis was evaluated in Boyden chambers and O2 (-) production by NBT reduction. In the FM patients, the exercise induced a decrease in the systemic concentration of IL-8, cortisol, NA, and eHsp72; as well as in the neutrophil's chemotaxis and O2 (-) production and in the inflammatory cytokine release by monocytes. This was contrary to the completely expected exercise-induced increase in all those biomarkers in HW. In conclusion, single sessions of moderate cycling can improve the inflammatory status in FM patients, reaching values close to the situation of aged-matched HW at their basal status. The neuroendocrine mechanism seems to be an exercise-induced decrease in the stress response of these patients.

Combined activity of post-exercise concentrations of NA and eHsp72 on human neutrophil function: role of cAMP

Extracellular heat shock proteins of 72 kDa (eHsp72) and noradrenaline (NA) can act as "danger signals" during exercise-induced stress by activating neutrophil function (chemotaxis, phagocytosis, and fungicidal capacity). In addition, post-exercise concentrations of NA increase the expression and release of Hsp72 by human neutrophils, and adrenoreceptors and cAMP are involved in the stimulation of neutrophils by eHsp72. This suggests an interaction between the two molecules in the modulation of neutrophils during exercise-induced stress. Given this context, the aim of the present investigation was to study the combined activity of post-exercise circulating concentrations of NA and eHsp72 on the neutrophil phagocytic process, and to evaluate the role of cAMP as intracellular signal in these effects. Results showed an accumulative stimulation of chemotaxis induced by NA and eHsp72. However, while NA and eHsp72, separately, stimulate the phagocytosis and fungicidal activity of neutrophils, when they act together they do not modify these capacities of neutrophils. Similarly, post-exercise concentrations of NA and eHsp72 separately increased the intracellular level of cAMP, but NA and eHsp72 acting together did not modify the intracellular concentration of cAMP. These results confirm that cAMP can be involved in the autocrine/paracrine physiological regulation of phagocytosis and fungicidal capacity of human neutrophils mediated by NA and eHsp72 in the context of exercise-induced stress.

Adrenoreceptors are involved in the stimulation of neutrophils by exercise-induced circulating concentrations of Hsp72: cAMP as a potential "intracellular danger signal"

Recently, the terms "stress mediators" or "danger signals" have come to be used to describe endogenous molecules that can be released in stress situations and activate the innate immune system even in the absence of antigenic stimuli. There is evidence suggesting that extracellular heat shock proteins of 72  kDa (eHsp72), together with noradrenaline (NA), are candidates as danger signals during exercise-induced stress, interacting in the activation of neutrophils. Previous studies have shown that the post-exercise circulating concentration of eHsp72 activates the phagocytic process of neutrophils with the participation of toll-like receptor 2, but that other receptors must also be involved. The present investigation evaluates the role of adrenoreceptors in the activation of the chemotaxis, phagocytosis, and fungicidal capacity of neutrophils by the post-exercise circulating concentration of eHsp72. The results showed that intact α- and β-adrenoreceptors are necessary for the stimulation of all stages of the phagocytic process by eHsp72. Also, eHsp72 increased the intracellular levels of cAMP, suggesting that it is an "intracellular danger signal" during stress-induced activation of neutrophils mediated by extracellular heat shock proteins. These results can contribute to better understanding the mechanisms involved in the regulation of the innate immune response mediated by "danger signals" during exercise, and probably during other stress situations.