Physical exercise as a human model of limited inflammatory response

1998 ◽  
Vol 76 (5) ◽  
pp. 589-597 ◽  
Author(s):  
Pang N Shek ◽  
Roy J Shephard

An inflammatory response represents a fundamental series of humoral and cellular reaction cascades in response to infection, tissue injury, and related insults. An excessive response is commonly seen under the pathological conditions of trauma, sepsis, and burns. It is becoming increasingly evident that most, if not all, of the distinguishing features of a classical inflammatory response are detectable in an exercising individual, namely mobilization and activation of granulocytes, lymphocytes, and monocytes; release of inflammatory factors and soluble mediators; involvement of active phase reactants; and activation of the complement and other reactive humoral cascade systems. While the manifestation of many exercise-induced immune and related changes has been reported and confirmed repeatedly, the underlying mechanisms triggering and modulating the elicited immune responses are, at best, poorly understood. Unlike the exaggerated and sometimes uncontrollable inflammatory response in septic and trauma patients resulting in morbidity and mortality, strenuous and severe exercise normally elicits an inflammatory response of a subclinical nature to facilitate the repairing process for site-specific tissue damage. Regardless of the inciting event, for example trauma, infection, or exercise, and given an appropriate triggering signal, a remarkably similar sequence of inflammatory reactions can be reproduced in the affected host. Therefore, physical exercise and training represent an acceptable and good model for the study of limited inflammatory responses in humans.Key words: trauma, infection, exercise, inflammatory response, cytokines.

2019 ◽  
Vol 65 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Hong Xiao Cui ◽  
Xiu Rong Xu

Rabbit is susceptible to intestinal infection, which often results in severe inflammatory response. To investigate whether the special community structure of rabbit intestinal bacteria contributes to this susceptibility, we compared the inflammatory responses of isolated rabbit crypt and villus to heat-treated total bacteria in pig, chicken, and rabbit ileal contents. The dominant phylum in pig and chicken ileum was Firmicutes, while Bacteroidetes was dominant in rabbit ileum. The intestinal bacteria from rabbit induced higher expression of toll-like receptor 4 (TLR4) in rabbit crypt and villus (P < 0.05). TLR2 and TLR3 expression was obviously stimulated by chicken and pig intestinal bacteria (P < 0.05) but not by those of rabbit. The ileal bacteria from those three animals all increased the expression of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) in crypts and villus (P < 0.05). Chicken and pig ileal bacteria also stimulated the expression of anti-inflammatory factors interferon beta (IFN-β) and IL-10 (P < 0.05), while those of rabbit did not (P > 0.05). In conclusion, a higher abundance of Gram-negative bacteria in rabbit ileum did not lead to more expressive pro-inflammatory cytokines in isolated rabbit crypt and villus, but a higher percentage of Lactobacillus in chicken ileum might result in more expressive anti-inflammatory factors.


Author(s):  
Geoffrey Bellingan ◽  
Brijesh V. Patel

Inflammation is the beneficial host response to foreign challenge or tissue injury that ultimately leads to the restoration of tissue structure and function. Critical illness is associated with an overwhelming and prolonged inflammatory activation. Resolution of the inflammatory response is an active process that requires removal of the inciting stimuli, cessation of the pro-inflammatory response, a timely coordinated removal of tissue leukocyte infiltration, a conversion from ‘toxic’ to reparative tissue environment, and restoration of normal tissue structure and function. Mortality may result from deficits in these resolution mechanisms. Improved delivery of critical care through prevention of harm and removal of stimuli has already delivered significant mortality benefits. Most critically-ill patients present with uncontrolled inflammation, hence anti-inflammatory strategies ameliorating this response are likely to be too late and thus futile. Rather, strategies augmenting endogenous pathways involved in the control and appropriate curtailment of such inflammatory responses may promote resolution, repair, and catabasis. Recent evidence showing that inflammation does not simply ‘fizzle out’, but its resolution involves an active and coordinated series of events. Dysfunction of these resolution checkpoints alters the normal inflammatory pathway, and is implicated in the induction and maintenance of states such as ARDS and sepsis. Improved understanding of resolution biology should provide translational pathways to not only improve survival, but also to prevent long-term morbidity resulting from tissue damage.


2011 ◽  
Vol 39 (2) ◽  
pp. 688-693 ◽  
Author(s):  
Jason P. McMorrow ◽  
Evelyn P. Murphy

Inflammation is paradoxical; it is essential for protection following biological, chemical or physical stimuli, but inappropriate or misdirected inflammation is responsible for tissue injury in a variety of inflammatory diseases. The polarization of immune cells is critical in controlling the stages of inflammatory response. The acute phase of inflammation is characterized by a T-lymphocyte:Th2 cytokine profile and involves a co-ordinated migration of immune cells to the site of injury where production of cytokines and acute-phase proteins brings about healing. However, persistent inflammation can result in inappropriate and prolonged T-lymphocyte:Th1 cytokine-mediated action and reaction of self-molecules, leading to a chronic phase in diseases such as RA (rheumatoid arthritis), Ps (psoriasis) and atherosclerosis. The inflammatory response is also controlled by activated macrophage cells, with classically activated (M1) cells producing a wide variety of pro-inflammatory mediators, while alternatively activated (M2) macrophages participate in anti-inflammatory response. Members of the NR4A subfamily (NR4A1/NUR77, NR4A2/NURR1 and NR4A3/NOR1) of orphan NRs (nuclear receptors) have emerged as key transcriptional regulators of cytokine and growth factor action in diseases affecting our aging population. As ligand-independent and constitutively active receptors, the activity of these transcription factors is tightly controlled at the level of expression, post-translational modification and subcellular localization. NR4A subfamily members are aberrantly expressed in inflamed human synovial tissue, psoriatic skin, atherosclerotic lesions, lung and colorectal cancer cells. Significantly, prolonged or inappropriate inflammatory responses contribute to the pathogenesis of these diseases. In activated cells, NR4A receptors are rapidly and potently induced, suggesting that these receptors may act as important transcriptional mediators of inflammatory signals. NR4A receptors may contribute to the cellular processes that control inflammation, playing a critical part in the contribution of chronic inflammation or they may have a protective role, where they may mediate pro-resolution responses. Here, we will review the contribution of the NR4A orphan NRs to integration of cytokine signalling in inflammatory disorders.


2020 ◽  
Author(s):  
Yang Jiao ◽  
Jianjian Wang ◽  
Huixue Zhang ◽  
Yuze Cao ◽  
Yang Qu ◽  
...  

Abstract Background Microglia are rapidly activated after ischemic stroke and participate in the occurrence of neuroinflammation, which exacerbates the injury of ischemic stroke. Receptor Interacting Serine Threonine Kinase 1 (RIPK1) is thought to be involved in the development of inflammatory responses, but its role in ischemic microglia remains unclear. Here, we applied recombinant human thioredoxin-1 (rhTrx-1), a potential neuroprotective agent, to explore the role of rhTrx-1 in inhibiting RIPK1-mediated neuroinflammatory responses in microglia. Method Middle cerebral artery occlusion (MCAO) and Oxygen and glucose deprivation (OGD) were conducted for in vivo and in vitro experimental stroke models. The expression of RIPK1 in microglia after ischemia was examined. The inflammatory response of microglia was analyzed after treatment with rhTrx-1 and Necrostatin-1 (Nec-1, inhibitors of RIPK1), and the mechanisms were explored. In addition, the effects of rhTrx-1 on neurobehavioral deficits and cerebral infarct volume were examined. Results RIPK1 expression was detected in microglia after ischemia. Molecular docking results showed that rhTrx-1 could directly bind to RIPK1. In vitro experiments found that rhTrx-1 reduced necroptosis, mitochondrial membrane potential damage, Reactive oxygen species (ROS) accumulation and NLR Family, pyrin domain-containing 3 protein (NLRP3) inflammasome activation by inhibiting RIPK-1 expression, and regulated microglial M1/M2 phenotypic changes, thereby reducing the release of inflammatory factors. Consistently, in vivo experiments found that rhTrx-1 treatment attenuated cerebral ischemic injury by inhibiting the inflammatory response. Conclusion Our study demonstrates the role of RIPK1 in microglia-arranged neuroinflammation after cerebral ischemia. Administration of rhTrx-1 provides neuroprotection in ischemic stroke-induced microglial neuroinflammation by inhibiting RIPK1 expression.


2019 ◽  
Vol 116 (7) ◽  
pp. 1357-1371 ◽  
Author(s):  
Laura Bevan ◽  
Zhi Wei Lim ◽  
Byrappa Venkatesh ◽  
Paul R Riley ◽  
Paul Martin ◽  
...  

Abstract Aims A robust inflammatory response to tissue injury is a necessary part of the repair process but the deposition of scar tissue is a direct downstream consequence of this response in many tissues including the heart. Adult zebrafish not only possess the capacity to regenerate lost cardiomyocytes but also to remodel and resolve an extracellular scar within tissues such as the heart, but this scar resolution process remains poorly understood. This study aims to characterize the scarring and inflammatory responses to cardiac damage in adult zebrafish in full and investigate the role of different inflammatory subsets specifically in scarring and scar removal. Methods and results Using stable transgenic lines, whole organ imaging and genetic and pharmacological interventions, we demonstrate that multiple inflammatory cell lineages respond to cardiac injury in adult zebrafish. In particular, macrophage subsets (tnfα+ and tnfα−) play prominent roles with manipulation of different phenotypes suggesting that pro-inflammatory (tnfα+) macrophages promote scar deposition following cardiac injury whereas tnfα− macrophages facilitate scar removal during regeneration. Detailed analysis of these specific macrophage subsets reveals crucial roles for Csf1ra in promoting pro-inflammatory macrophage-mediated scar deposition. Additionally, the multifunctional cytokine Osteopontin (Opn) (spp1) is important for initial scar deposition but also for resolution of the inflammatory response and in late-stage ventricular collagen remodelling. Conclusions This study demonstrates the importance of a correctly balanced inflammatory response to facilitate scar deposition during repair but also to allow subsequent scar resolution, and full cardiac regeneration, to occur. We have identified Opn as having both pro-fibrotic but also potentially pro-regenerative roles in the adult zebrafish heart, driving Collagen deposition but also controlling inflammatory cell resolution.


Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Mehwish A Mirza ◽  
Kathryn Bentivegna ◽  
Rodney Ritzel ◽  
Kaitlyn H Hajdarovic ◽  
Louise D McCullough ◽  
...  

Background and Purpose: Neonatal arterial ischemic stroke (NAIS) is an important cause of motor and cognitive impairment in children. Clinically, male infants are more vulnerable to ischemic insult and suffer more long-term deficits than female infants though the mechanisms remain elusive. Inflammatory processes are fundamental in the pathophysiology of ischemia as microglial activation initiates the inflammatory response after ischemia. Recent studies report a sexual dimorphism in microglia numbers and expression of activation markers in neonatal brains under normal conditions. How these basal sex differences in microglia affect NAIS remains largely unexplored. This study investigated sex differences in stroke phenotypes and inflammation triggered by NAIS. We hypothesize that ischemia induces sex-specific tissue injury in male and female neonates, which is related to differences in microglial activation and inflammatory responses. Methods: Male and female C57BL6 mice were subjected to 60-minute Rice-Vanucci Modeling at post-natal day 10 (P10) to induce NAIS. Stroke outcomes were measured at 24 hours, 72 hours and 7 days after stroke. Microglial activation and inflammatory responses were evaluated by flow cytometry, immunohistochemistry, and multiplex cytokine analysis. Results: At 24 hours no difference in infarct volumes (total infarct: male vs. female 46.6±7.2% vs. 43.2±9.3%, n=6/gp) and in Iba-1 staining of the ischemic brain were seen between male and female neonates. However, at 72 hours female neonates exhibited significantly smaller infarct size and improved behavior outcomes compared to males (total infarct: male vs. female 43.1±9.9% vs. 27.1±8.8%, n=6/gp, p <.05). Male animals demonstrated increased microglial activation and up-regulated inflammatory response compared to females at 72 hours. This male-specific phenotype was also seen at 7 days after injury. There was no difference in hormone levels at any of the three time points after stroke. Conclusions: Acute ischemia leads to an equivalent primary brain injury in male and female P10 mice. However, infarct damage worsens in males at sub-acute time points vs. females, as does the immune response. This sex difference independent of hormone levels exists in NAIS.


2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Naru Morita ◽  
Toshio Hosaka ◽  
Atsuko Kitahara ◽  
Toshitaka Murashima ◽  
Hirohisa Onuma ◽  
...  

Objective. A growing body of evidence indicates that AMP-activated protein kinase (AMPK) contributes to not only energy metabolic homeostasis but also the inhibition of inflammatory responses. However, the underlying mechanisms remain unclear. To elucidate the role of AMPK, in this study, we observed the effects of AMPK activation on monocyte chemoattractant protein-1 (MCP-1) release in mature 3T3-L1 adipocytes. Methods. We observed signal transduction pathways regulating MCP-1, which increased in obese adipocytes, in an in vitro model of hypertrophied 3T3-L1 adipocytes preloaded with palmitate. Results. Palmitate-preloaded cells exhibited significant increase in MCP-1 release and triglyceride (TG) deposition. Increased MCP-1 release and TG deposition were significantly decreased by an AMPK activator. In addition, the AMPK activator not only markedly diminished MCP-1 secretion but also augmented phosphorylation of nuclear factor-κB (NF-κB) and extracellular signal-regulated kinase (ERK) 1/2. In contrast, MCP-1 release suppression was abolished by the AMPK inhibitor compound C and the MEK inhibitor U0126. Conclusions. MCP-1 release from hypertrophied adipocytes is suppressed by AMPK activation through the NF-κB and ERK pathways. These findings provide evidence that AMPK plays a crucial role in ameliorating obesity-induced inflammation.


2009 ◽  
Vol 101 (S1) ◽  
pp. 1-45 ◽  
Author(s):  
P. C. Calder ◽  
R. Albers ◽  
J.-M. Antoine ◽  
S. Blum ◽  
R. Bourdet-Sicard ◽  
...  

Inflammation is a stereotypical physiological response to infections and tissue injury; it initiates pathogen killing as well as tissue repair processes and helps to restore homeostasis at infected or damaged sites. Acute inflammatory reactions are usually self-limiting and resolve rapidly, due to the involvement of negative feedback mechanisms. Thus, regulated inflammatory responses are essential to remain healthy and maintain homeostasis. However, inflammatory responses that fail to regulate themselves can become chronic and contribute to the perpetuation and progression of disease. Characteristics typical of chronic inflammatory responses underlying the pathophysiology of several disorders include loss of barrier function, responsiveness to a normally benign stimulus, infiltration of inflammatory cells into compartments where they are not normally found in such high numbers, and overproduction of oxidants, cytokines, chemokines, eicosanoids and matrix metalloproteinases. The levels of these mediators amplify the inflammatory response, are destructive and contribute to the clinical symptoms. Various dietary components including long chain ω-3 fatty acids, antioxidant vitamins, plant flavonoids, prebiotics and probiotics have the potential to modulate predisposition to chronic inflammatory conditions and may have a role in their therapy. These components act through a variety of mechanisms including decreasing inflammatory mediator production through effects on cell signaling and gene expression (ω-3 fatty acids, vitamin E, plant flavonoids), reducing the production of damaging oxidants (vitamin E and other antioxidants), and promoting gut barrier function and anti-inflammatory responses (prebiotics and probiotics). However, in general really strong evidence of benefit to human health through anti-inflammatory actions is lacking for most of these dietary components. Thus, further studies addressing efficacy in humans linked to studies providing greater understanding of the mechanisms of action involved are required.


2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1518-1518
Author(s):  
Sarah Berry ◽  
Mohsen Mazidi ◽  
Paul Franks ◽  
Ana Valdes ◽  
Naveed Sattar ◽  
...  

Abstract Objectives Postprandial glycemia (PPG) and lipemia (PPL) initiate an acute inflammatory response, which may be relevant to future CVD. We characterised the impact of PPL and PPG on inflammatory responses using traditional (IL-6) and emerging (glycoprotein acetyls; GlycA) biomarkers of inflammation in a large scale, tightly controlled study (PREDICT 1; NCT03479866) and an independent validation study (InterCardio; NCT03438084). Methods The PREDICT 1 dietary intervention study of 1102 healthy individuals from the US and UK, assessed the postprandial (0–6 h) metabolic responses to sequential mixed-nutrient meals (50 g fat and 85 g carb at 0 h; 22 g fat and 71 g carb at 4 h). Baseline microbial diversity (16S Shannon diversity) and visceral fat mass (VFM; based on DXA) were also measured. Results were validated in an independent randomised crossover trial (n = 50). For both studies, glucose, triacylglycerol (TG), IL-6 and GlycA were measured at multiple intervals. Results In PREDICT 1, GlycA and IL-6 concentrations increased significantly after meals (by 4.5 and 169%; peak 6 h, respectively) but were not correlated. Peak postprandial TG and glucose concentrations were strongly associated with GlycA (r = 0.832 and r = 0.239, respectively) but not IL-6. Machine learning with cross-validation, revealed that PPL was the strongest predictor of postprandial GlycA. There was evidence of an interaction; individuals with higher microbial diversity and lower VFM had an attenuated inflammatory response. Individuals eliciting an enhanced response (30% rise at 6 h) had higher predicted CVD risk compared to the rest of the cohort. In the InterCardio study, the postprandial inflammatory increase in GlycA was also significantly correlated with PPL and varied within the four different types of fat tested. Conclusions In the first study to investigate postprandial inflammation at scale, we observed that PPL was a stronger determinant of systemic inflammation compared with PPG. The clinically significant and variable postprandial inflammatory response, and its association with lipemia and glycemia, highlights the potential for personalized dietary strategies to lower postprandial metabolic responses to reduce low grade inflammatory related diseases. Funding Sources NIHR, Wellcome Trust, Zoe Global Ltd, BBSRC DRINC.


2021 ◽  
Vol 15 ◽  
Author(s):  
Yaru Xu ◽  
Ge Gao ◽  
Xiaoru Sun ◽  
Qidong Liu ◽  
Cheng Li

Postoperative delirium (POD) is one of the most important complications after surgery with general anesthesia, for which the neurotoxicity of general anesthetics is a high-risk factor. However, the mechanism remains largely unknown, which also hinders the effective treatment of POD. Here, we confirmed that a clinical concentration of the general anesthetic sevoflurane increased the expression of inflammatory factors and activated the caspase-3 by upregulating ATPase inhibitory factor 1 (ATPIF1) expression in microglia. Upregulation of ATPIF1 decreased the synthesis of ATP which is an important signaling molecule secreted by microglia. Extracellular supplementation with ATP attenuated the microglial inflammatory response and caspase-3 activation caused by sevoflurane or overexpression of ATPIF1. Additionally, the microglial inflammatory response further upregulated ATPIF1 expression, resulting in a positive feedback loop. Animal experiments further indicated that intraperitoneal injection of ATP significantly alleviated sevoflurane anesthesia-induced POD-related anxiety behavior and memory damage in mice. This study reveals that ATPIF1, an important protein regulating ATP synthesis, mediates sevoflurane-induced neurotoxicity in microglia. ATP supplementation may be a potential clinical treatment to alleviate sevoflurane-induced POD.


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