Role of alpha- and beta-adrenoreceptors in rat monocyte/macrophage function at rest and acute exercise

Sedentary Behaviour Impairs Skeletal Muscle Repair Modulating the Inflammatory Response

This study investigated whether sedentary behaviour modulates skeletal-muscle repair and tissue inflammatory response after cardiotoxin (CTX)-induced injury. Singly caged rats spent 8 weeks either as a sedentary group (SED, n = 15) or as a control group (EX, n = 15)—caged with running wheels for voluntary running. All rats had each tibial anterior muscle infused either with CTX (CTX; right muscle) or saline solution (Sham; left muscle) and were sacrificed (n = 5 per group) on the 1st, 7th, and 15th day post-injection (dpi). Histological and immunohistochemical analyses were used to calculate myotube percentage and fibrosis accretion, and quantify the number of neutrophils and M1 and M2 macrophage subtypes. The SED group showed an increased number of both neutrophils and M1 macrophages (7th and 15th dpi) compared to the EX group (p < 0.01). The EX group showed an increased number of M2 macrophages on the 1st dpi. On the 7th dpi, the SED group showed a lower myotube percentage compared to the EX group (p < 0.01) and on the 15th dpi showed only 54% of normal undamaged fibres compared to 90% from the EX group (p < 0.01). The SED group showed increased fibrosis on both the 7th and 15th dpi. Our results show that sedentary behaviour affects the inflammatory response, enhancing and prolonging the Th1 phase, and delays and impairs the SMR process.

Elevated Extracellular HSP72 and Blunted Heat Shock Response in Severe COVID-19 Patients

Aims: We hypothesized that critically ill patients with SARS-CoV-2 infection and insulin resistance would present a reduced Heat Shock Response (HSR), which is a pathway involved in proteostasis and anti-inflammation, subsequently leading to worse outcomes and higher inflammation. In this work we aimed: (i) to measure the concentration of extracellular HSP72 (eHSP72) in patients with severe COVID-19 and in comparison with noninfected patients; (ii) to compare the HSR between critically ill patients with COVID-19 (with and without diabetes); and (iii) to compare the HSR in these patients with noninfected individuals. Methods: Sixty critically ill adults with acute respiratory failure with SARS-CoV-2, with or without diabetes, were selected. Noninfected subjects were included for comparison (healthy, n = 19 and patients with diabetes, n = 22). Blood samples were collected to measure metabolism (glucose and HbA1c); oxidative stress (lypoperoxidation and carbonyls); cytokine profile (IL-10 and TNF); eHSP72; and the HSR (in vitro). Results: Patients with severe COVID-19 presented higher plasma eHSP72 compared with healthy individuals and noninfected patients with diabetes. Despite the high level of plasma cytokines, no differences were found between critically ill patients with COVID-19 with or without diabetes. Critically ill patients, when compared to noninfected, presented a blunted HSR. Oxidative stress markers followed the same pattern. No differences in the HSR (extracellular/intracellular level) were found between critically ill patients, with or without diabetes. Conclusions: We demonstrated that patients with severe COVID-19 have elevated plasma eHSP72 and that their HSR is blunted, regardless of the presence of diabetes. These results might explain the uncontrolled inflammation and also provide insights on the increased risk in developing type 2 diabetes after SARS-CoV-2 infection.

Chaperone duality: the role of extracellular and intracellular HSP70 as a biomarker of endothelial dysfunction in the development of atherosclerosis

The 70-kDa heat shock proteins (HSP70) may provide relevant information about the endothelial dysfunction in cardiovascular diseases. Located in the intracellular milieu (iHSP70), they are essential chaperones that inhibit nuclear factor kappa B activation, stimulate nitric oxide production and superoxide dismutase activity, and inhibit apoptosis. However, under stressful conditions, HSP70 can be released into the extracellular medium (eHSP70) and act as an inflammatory mediator. Although studies have reported the vasoprotective role of iHSP70, the evidence regarding eHSP70 is contradictory. eHSP70 can activate NFκB and activator protein-1, thus stimulating the release of inflammatory cytokines and production of reactive oxygen species. Due to the antagonistic nature of HSP70 according to its location, the eHSP70/iHSP70 ratio (Heck index) has been proposed as a better marker of inflammatory status; however, more studies are required to confirm this hypothesis. Therefore, this review summarises studies that, together, describe the role of HSP70 in endothelial dysfunction.

A-family anti-inflammatory cyclopentenone prostaglandins: A novel class of non-statin inhibitors of HMG-CoA reductase

Disruption of the intracellular lipid balance leading to cholesterol accumulation is one of the features of cells that participate in the development of atherosclerotic lesions. Evidence form our laboratory indicates that anti-inflammatory cyclopentenone prostaglandins (cyPGs) of A- and J-family deviate lipid metabolism from the synthesis of cholesterol and cholesteryl esters to the synthesis of phospholipids in foam-cell macrophages. cyPGs possessing an α,β-unsaturated cyclopentane ring are highly electrophilic substances able to promptly react with reactive cysteines of intracellular molecules through Michael addition. On the other hand, HMG-CoA reductase (HMGCR), the enzyme responsible for the rate-limiting step in cholesterol biosynthesis, presents critically reactive cysteines at the entry of catalytic domain, particularly Cys561, that could be target of cyPG inhibition. In the present study, we showed that cyPGs (but not other non-α,β-unsaturated PGs) physically interact with HMGCR, in a dithiothreitol- and β-mercaptoethanol-sensitive way, and block the activity of the catalytic subunit of the enzyme (IC₅₀ for PGA₂ = 0.17 μM). PGA₂ inhibits HMGCR activity in cultured rat and human macrophages/macrophage-foam cells and leads to enhanced expression of HMGCR protein, as observed with statins. In cell culture models, PGA₂ effectively inhibits the reductase at non-toxic doses (e.g., 1 μM) that block cell proliferation thus suggesting that part of the well-known antiproliferative effect of PGA₂ may be due to its ability of blocking HMGCR activity, as cells cannot proliferate without a robust cholesterogenesis. Therefore, besides the powerfully anti-inflammatory and antiproliferative effects, the anticholesterogenic effects of PGA₂ should be exploited in atherosclerosis therapeutics.

Role of adrenergic receptor signalling in neuroimmune communication

Neuroimmune communication plays a crucial role in maintaining homeostasis and promptly responding to any foreign insults. Sympathetic nerve fibres are innervated into all the lymphoid organs (bone marrow, thymus, spleen, and lymph nodes) and provide a communication link between the central nervous system (CNS) and ongoing immune response in the tissue microenvironment. Neurotransmitters such as catecholamines (epinephrine and norepinephrine) bind to adrenergic receptors present on most immune and non-immune cells, establish a local neuroimmune-communication system, and help regulate the ongoing immune response. The activation of these receptors varies with the type of receptor-activated, target cell, the activation status of the cells, and timing of activation. Activating adrenergic receptors, specifically β-adrenergic signalling in immune cells leads to activation of the cAMP-PKA pathway or other non-canonical pathways. It predominantly leads to immune suppression such as inhibition of IL-2 secretion and a decrease in macrophages phagocytosis. This review discusses the expression of different adrenergic receptors in various immune cells, signalling, and how it modulates immune cell function and contributes to health and diseases. Understanding the neuroimmune communication through adrenergic receptor signalling in immune cells could help to design better strategies to control inflammation and autoimmunity.

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Primary and secondary lymphoid organs are innervated with sympathetic nerve fibres.

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Adrenergic receptor expression on immune and non-immune cells establishes a local neuroimmune communication system.

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Adrenergic receptor signalling in immune cells controls the differentiation and function of various immune cells.

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Modulating adrenergic receptor signalling with a specific agonist or antagonist also affect the immune response.

Coronavirus infection (SARS-CoV-2) in obesity and diabetes comorbidities: is heat shock response determinant for the disease complications?

Chronic inflammation is involved in the pathogenesis of several metabolic diseases, such as obesity and type 2 diabetes mellitus (T2DM). With the recent worldwide outbreak of coronavirus disease (SARS-CoV-2), it has been observed that individuals with these metabolic diseases are more likely to develop complications, increasing the severity of the disease and a poorer outcome. Coronavirus infection leads to the activation of adaptive and innate immune responses, resulting in massive inflammation (to so called cytokine storm), which in turn can lead to damage to various tissues, septic shock and multiple organ failure. Recent evidence suggests that the common link between metabolic diseases and SARS-CoV-2 is the inflammatory response (chronic/low-grade for metabolic diseases and acute/intense in coronavirus infection). However, the ability of the infected individuals to resolve the inflammation has not yet been explored. The heat shock response (HSR), an important anti-inflammatory pathway, is reduced in patients with metabolic diseases and, consequently, may impair inflammation resolution and control in patients with SARS-CoV-2, thus enabling its amplification and propagation through all tissues. Herein, we present a new hypothesis that aims to explain the increased severity of SARS-CoV-2 infection in people with metabolic diseases, and the possible benefits of HSR-inducing therapies to improve the inflammatory profile in these patients.

Heat shock response to exercise in pancreatic islets of obese mice

Chronic obesity imposes an organismal state of low-grade inflammation because the physiological resolution of inflammation is progressively repressed giving rise to cellular senescence and its accompanying Senescence-Associated Secretory Phenotype (SASP), which avoids apoptosis but perpetuates the relay of inflammatory signals from adipose tissue toward the rest of the body. Conversely, resolution of inflammation depends on the integrity of heat shock response (HSR) pathway that leads to the expression of cytoprotective and anti-inflammatory protein chaperones of the 70 kDa family (HSP70). However, chronic exposure to the aforementioned injuring factors leads to SASP, which, in turn, suppresses the HSR. A main metabolic tissue severely jeopardized by obesity-related dysfunctions is the endocrine pancreas, particularly β-cells of the islets of Langerhans. Because exercise is a powerful inducer of HSR and predicted to alleviate negative health outcomes of obesity, we sought whether obesity influence HSP70 expression in pancreatic islets and other metabolic tissues (adipose tissue and skeletal muscle) of adult B6.129SF2/J mice fed on a high-fat diet (HFD) for 13 weeks since the weaning and whether acute exercise as well as moderate-intensity exercise training (8 weeks) could interfere with this scenario. We showed that acute exercise of moderate intensity protects pancreatic islets against cytokine-induced cell death. In addition, acute exercise challenge time-dependently increased islet HSP70 that peaked at 12 h post-exercise in both trained and untrained mice fed on a control diet, suggesting an adequate HSR to exercise training. Unexpectedly, however, neither exercise training nor acute exercise challenges were able to increase islet HSP70 contents in trained mice submitted to HFD, but only in untrained HFD animals. In parallel, HFD disrupted glycemic status which is accompanied by loss of muscular mass resembling sarcopenic obesity that could not be rescued by exercise training. These results suggest that exercise influences HSR in pancreatic islets but obesity undermines islet, muscle and adipose tissue HSR, which is associated with metabolic abnormalities observed in such tissues.

Induction chemotherapy reduces extracellular heat shock protein 72 levels, inflammation, lipoperoxidation and changes insulin sensitivity in children and adolescents newly diagnosed with acute lymphoblastic leukemia

Background

Acute lymphoblastic leukemia (ALL) is associated with higher levels of pro-inflammatory cytokines and oxidative stress. Recently, the levels of extracellular heat shock protein 72 (eHSP72) were found to be elevated in ALL, and its elevation associated with poor prognosis. Therefore, considering the possible role of eHSP72 as a modulator of the immunological system and metabolism, the aim of this study was to describe the response of eHSP72 to the induction phase of chemotherapy, along with metabolic, inflammatory and oxidative stress markers, in children and adolescents newly diagnosed with ALL.

Methods

Nineteen patients were recruited and analysed before and after the induction phase of chemotherapy (with 28 days of duration). Blood samples were taken for the analysis of C-reactive protein (CRP), levels of lipoperoxidation, insulin (and HOMA-IR), cortisol, glucose, lipid profile and eHSP72.

Results

We found that induction phase of chemotherapy leads to a drop in glucose levels (from 101.79±19 to 75.8±9.7 mg/dL), improvements on inflammation (CRP levels, p<0.01) and oxidative stress (TBARS levels, p<0.01), reduction on eHSP72 (p=0.03) and improved insulin sensitivity (HOMA-IR, p=0.02).

Conclusion

Our results indicate that eHSP72 may have an immune and metabolic role and could be used as a marker of the treatment success and metabolic changes in children with ALL.

Effects of High-Intensity Interval and Moderate-Intensity Continuous Exercise on Inflammatory, Leptin, IgA, and Lipid Peroxidation Responses in Obese Males

Purpose: To compare the effects of a single high-intensity interval exercise session (HIIE) with a moderate-intensity continuous exercise session (MICE) on the inflammatory profile, IgA levels, and lipid peroxidation in sedentary obese males.

Methods: Ten sedentary obese men (age 28.5 ± 2.7 years; BMI 35.9 ± 4.9 kg/m²; body fat 40.6 ± 2.0%) performed three experimental sessions, on separate days with 1 week wash-out period between interventions, according to a randomized order: (1) HIIE: 10 × 60 s at 90% of the HR_max alternated by 60 s of active recovery; (2) MICE: 20 min at 70% of the HR_max; (3) Rest—control. Blood and saliva samples were collected before, immediately after and 60 min after the end of each session in order to analyse serum levels of cytokines, IgA, and lipoperoxidation markers.

Results: Leptin levels decreased immediately after HIIE (P = 0.033) and was different from the MICE (P = 0.025). IFN-γ levels were reduced immediately after (P = 0.032) and 60 min after HIIE (P = 0.003) compared to baseline, and it also increased IL-4 levels immediately after exercise (P = 0.007) compared to resting values. MICE promoted an increase in IFN-γ levels immediately after exercise (P = 0.025) and 60 min after exercise (P = 0.004) in relation to baseline. Both exercise conditions increased IL-6 levels up to 60 min after exercise (P < 0.05). The IFN-γ/IL-4 ratio decreased immediately after (P = 0.002) and 60 min after HIIE (P = 0.005) in relation to pre-exercise. No changes were found for IgA-S and TBARS for any of the conditions.

Conclusion: A single HIIE session is able to decrease IFN-γ/IL-4 ratio, indicating an anti-inflammatory response, without alterations in the function of the mucosal immune system and lipoperoxidation. On the other hand, a brief session of MICE induced changes in the pattern of cytokines associated with increased cellular immune function.

Nitric oxide-heat shock protein axis in menopausal hot flushes: neglected metabolic issues of chronic inflammatory diseases associated with deranged heat shock response

BACKGROUND

Although some unequivocal underlying mechanisms of menopausal hot flushes have been demonstrated in animal models, the paucity of similar approaches in humans impedes further mechanistic outcomes. Human studies might show some as yet unexpected physiological mechanisms of metabolic adaptation that permeate the phase of decreased oestrogen levels in both symptomatic and asymptomatic women. This is particularly relevant because both the severity and time span of hot flushes are associated with increased risk of chronic inflammatory disease. On the other hand, oestrogen induces the expression of heat shock proteins of the 70 kDa family (HSP70), which are anti-inflammatory and cytoprotective protein chaperones, whose expression is modulated by different types of physiologically stressful situations, including heat stress and exercise. Therefore, lower HSP70 expression secondary to oestrogen deficiency increases cardiovascular risk and predisposes the patient to senescence-associated secretory phenotype (SASP) that culminates in chronic inflammatory diseases, such as obesities, type 2 diabetes, neuromuscular and neurodegenerative diseases.

OBJECTIVE AND RATIONALE

This review focuses on HSP70 and its accompanying heat shock response (HSR), which is an anti-inflammatory and antisenescent pathway whose intracellular triggering is also oestrogen-dependent via nitric oxide (NO) production. The main goal of the manuscript was to show that the vasomotor symptoms that accompany hot flushes may be a disguised clue for important neuroendocrine alterations linking oestrogen deficiency to the anti-inflammatory HSR.

SEARCH METHODS

Results from our own group and recent evidence on hypothalamic control of central temperature guided a search on PubMed and Google Scholar websites.

OUTCOMES

Oestrogen elicits rapid production of the vasodilatory gas NO, a powerful activator of HSP70 expression. Whence, part of the protective effects of oestrogen over cardiovascular and neuroendocrine systems is tied to its capacity of inducing the NO-elicited HSR. The hypothalamic areas involved in thermoregulation (infundibular nucleus in humans and arcuate nucleus in other mammals) and whose neurons are known to have their function altered after long-term oestrogen ablation, particularly kisspeptin-neurokinin B-dynorphin neurons, (KNDy) are the same that drive neuroprotective expression of HSP70 and, in many cases, this response is via NO even in the absence of oestrogen. From thence, it is not illogical that hot flushes might be related to an evolutionary adaptation to re-equip the NO-HSP70 axis during the downfall of circulating oestrogen.

WIDER IMPLICATIONS

Understanding of HSR could shed light on yet uncovered mechanisms of menopause-associated diseases as well as on possible manipulation of HSR in menopausal women through physiological, pharmacological, nutraceutical and prebiotic interventions. Moreover, decreased HSR indices (that can be clinically determined with ease) in perimenopause could be of prognostic value in predicting the moment and appropriateness of starting a HRT.

Acute exercise boosts cell proliferation and the heat shock response in lymphocytes: correlation with cytokine production and extracellular-to-intracellular HSP70 ratio

Exercise stimulates immune responses, but the appropriate "doses" for such achievements are unsettled. Conversely, in metabolic tissues, exercise improves the heat shock (HS) response, a universal cytoprotective response to proteostasis challenges that are centred on the expression of the 70-kDa family of intracellular heat shock proteins (iHSP70), which are anti-inflammatory. Concurrently, exercise triggers the export of HSP70 towards the extracellular milieu (eHSP70), where they work as pro-inflammatory cytokines. As the HS response is severely compromised in chronic degenerative diseases of inflammatory nature, we wondered whether acute exercise bouts of different intensities could alter the HS response of lymphocytes from secondary lymphoid organs and whether this would be related to immunoinflammatory responses. Adult male Wistar rats swam for 20 min at low, moderate, high or strenuous intensities as per an overload in tail base. Controls remained at rest under the same conditions. Afterwards, mesenteric lymph node lymphocytes were assessed for the potency of the HS response (42 °C for 2 h), NF-κB binding activity, mitogen-stimulated proliferation and cytokine production. Exercise stimulated cell proliferation in an "inverted-U" fashion peaking at moderate load, which was paralleled by suppression of NF-κB activation and nuclear location, and followed by enhanced HS response in relation to non-exercised animals. Comparative levels of eHSP70 to iHSP70 (H-index) matched IL-2/IL-10 ratios. We conclude that exercise, in a workload-dependent way, stimulates immunoinflammatory performance of lymphocytes of tissues far from the circulation and this is associated with H-index of stress response, which is useful to assess training status and immunosurveillance balance.

Estrogen deprivation does not affect vascular heat shock response in female rats: a comparison with oxidative stress markers

Hot flashes, which involve a tiny rise in core temperature, are the most common complaint of peri- and post-menopausal women, being tightly related to decrease in estrogen levels. On the other hand, estradiol (E2) induces the expression of HSP72, a member of the 70 kDa family of heat shock proteins (HSP70), which are cytoprotective, cardioprotective, and heat inducible. Since HSP70 expression is compromised in age-related inflammatory diseases, we argued whether the capacity of triggering a robust heat shock (HS) response would be still present after E2 withdrawal. Hence, we studied the effects of HS treatment (hot tub) in female Wistar rats subjected to bilateral ovariectomy (OVX) after a 7-day washout period. Twelve h after HS, the animals were killed and aortic arches were surgically excised for molecular analyses. The results were compared with oxidative stress markers in the plasma (superoxide dismutase, catalase, and lipoperoxidation) because HSP70 expression is also sensitive to redox regulation. Extracellular (plasma) to intracellular HSP70 ratio, an index of systemic inflammatory status, was also investigated. The results showed that HS response was preserved in OVX animals, as inferred from HSP70 expression (up to 40% rise, p < 0.01) in the aortas, which was accompanied by no further alterations in oxidative stress, hematological parameters, and glycemic control either. This suggests that the lack of estrogen per se could not be solely ascribed as the unique source of low HSP70 expression as observed in long-term post-menopausal individuals. As a consequence, periodic evaluation of HSP70 status (iHSP70 vs. eHSP70) may be of clinical relevance because decreased HS response capacity is at the center of the onset of menopause-related dysfunctions.

Physical exercise associated with NO production: signaling pathways and significance in health and disease

Here we review available data on nitric oxide (NO)-mediated signaling in skeletal muscle during physical exercise. Nitric oxide modulates skeletal myocyte function, hormone regulation, and local microcirculation. Nitric oxide underlies the therapeutic effects of physical activity whereas the pharmacological modulators of NO-mediated signaling are the promising therapeutic agents in different diseases. Nitric oxide production increases in skeletal muscle in response to physical activity. This molecule can alter energy supply in skeletal muscle through hormonal modulation. Mitochondria in skeletal muscle tissue are highly abundant and play a pivotal role in metabolism. Considering NO a plausible regulator of mitochondrial biogenesis that directly affects cellular respiration, we discuss the mechanisms of NO-induced mitochondrial biogenesis in the skeletal muscle cells. We also review available data on myokines, the molecules that are expressed and released by the muscle fibers and exert autocrine, paracrine and/or endocrine effects. The article suggests the presence of putative interplay between NO-mediated signaling and myokines in skeletal muscle. Data demonstrate an important role of NO in various diseases and suggest that physical training may improve health of patients with diabetes, chronic heart failure, and even degenerative muscle diseases. We conclude that NO-associated signaling represents a promising target for the treatment of various diseases and for the achievement of better athletic performance.

The regulatory roles of NADPH oxidase, intra- and extra-cellular HSP70 in pancreatic islet function, dysfunction and diabetes

The 70 kDa heat-shock protein (HSP70) family is important for a dynamic range of cellular processes that include protection against cell stress, modulation of cell signalling, gene expression, protein synthesis, protein folding and inflammation. Within this family, the inducible 72 kDa and the cognate 73 kDa forms are found at the highest level. HSP70 has dual functions depending on location. For example, intracellular HSP70 (iHSP70) is anti-inflammatory whereas extracellular HSP70 (eHSP70) has a pro-inflammatory function, resulting in local and systemic inflammation. We have recently identified a divergence in the levels of eHSP70 and iHSP70 in subjects with diabetes compared with healthy subjects and also reported that eHSP70 was correlated with insulin resistance and pancreatic β-cell dysfunction/death. In the present review, we describe possible mechanisms by which HSP70 participates in cell function/dysfunction, including the activation of NADPH oxidase isoforms leading to oxidative stress, focusing on the possible role of HSPs and signalling in pancreatic islet α- and β-cell physiological function in health and Type 2 diabetes mellitus.