Exercise Immunology Review

Respiratory viruses are the most frequent causative agents of disease in humans and thus also in elite athletes. The COVID-19 pandemic has recently emphasized the entire spectrum of respiratory tract infections worldwide. Understanding the basic elements of respiratory viral infections is a fundamental requirement from the perspective of etiological diagnostics, treatment, and prevention strategy planning, as well as resource allocation.

Macrophage accumulation in the adipose tissue and changes in their inflammatory phenotype is a hallmark of obesity-induced inflammation, notably forming inflammatory structures known as "crown-like structures (CLS)". Exercise can be a key strategy to improve inflammation-related complications, but it is crucial to consider that, although exercise generally exerts systemic and local anti-inflammatory effects, this depends on the basal inflammatory status and exercise modality. In this context, the "bioregulatory effect of exercise" implies to achieve the reduction or prevention of an excessive inflammatory response and also the preservation or stimulation of the innate response...

BACKGROUND: Exercise might exert anti-tumoral effects in adult cancers but this question remains open in pediatric tumors, which frequently show a different biology compared to adult malignancies. We studied the effects of an exercise intervention on physical function, immune variables and tumoral response in a preclinical model of a highly aggressive pediatric cancer, high-risk neuroblastoma (HR-NB). METHODS: 6-8-week-old male mice with orthotopically-induced HR-NB were assigned to a control (N = 13) or exercise (5-week combined [aerobic+resistance]) group (N = 17)...

BACKGROUND: Both acute and chronic exercise have profound effects on systemic metabolism and the immune system. While acute exercise transiently disturbs energy homeostasis and elicits acute inflammation, exercise training improves systemic metabolic capacity, lowers basal inflammation, and reduces infection risk. Accordingly, accumulating evidence indicates links between systemic and immune cell metabolism and suggests that cellular metabolism may be an important way exercise influences immune function...

BACKGROUND: In the pathogenesis of knee osteoarthritis (KOA), inflammatory mediators play an important role. However, the precise underlying mechanism by which regular exercise therapy (ET) exert effects on the immune system in KOA patients is unknown. OBJECTIVES: The aim of this systematic review was to investigate the basal and acute effects of ET on inflammatory biomarkers and brain derived neurotrophic factor (BDNF) in KOA patients. METHODS: PubMed, Web Of Science and PEDro were systematically searched for appropriate studies...

There is a knowledge gap regarding the consequences of exercise during acute infections in humans and contradictory findings in animal studies, compromising public health advice on the potential benefits of physical activity for immunity. Here, we carried out a meta-analysis of studies of the effects of moderate exercise (ME) and exercise until fatigue (EF) on symptom severity, morbidity and mortality during viral infection in animal models. The systematic review on PubMed, Scopus, Embase, Web of Science, Cochrane and EBSCOhost (CINAHL and SPORT Discus) identified 8 controlled studies, with 15 subgroups within them...

Individuals who participate in regular exercise over time have a markedly reduced risk of cardiovascular disease. Paradoxically, in susceptible individuals with underlying, often undiagnosed, disease states, exercise may acutely increase an individual's risk of cardiovascular events during and immediately following physical exertion. Exercise is thought to evoke conditions that trigger atheromatous plaque rupture or trigger life threatening arrhythmias in individuals with pre-existing, vulnerable coronary artery and inherited cardiovascular disease respectively...

BACKGROUND: The complement system is comprised of the classical, lectin and alternative pathways that result in the formation of: pro-inflammatory anaphylatoxins; opsonins that label cells for phagocytic removal; and, a membrane attack complex that directly lyses target cells. Complement-dependent cytotoxicity (CDC) - cell lysis triggered by complement protein C1q binding to the Fc region of antibodies bound to target cells - is another effector function of complement and a key mechanism-of-action of several monoclonal antibody therapies...

BACKGROUND: The nervous system integrates the immune system in the systemic effort to maintain or restore the organism's homeostasis. Acute bouts of exercise may alter the activity of specific pathways associated with neuroendocrine regulation of the immune system. OBJECTIVE: To examine the acute effects of heavy resistance exercise on biomarkers of neuroendocrine-immune regulation in healthy adults. METHODS: A systematic literature search was conducted using PubMed, Cochrane Controlled Trials Register, Web of Science and SportDiscus with no date restrictions up to March 2021...

Traumatic brain injury (TBI) is the largest cause of death and disability globally. The physical and psychosocial consequences after TBI can persist for prolonged periods, and lead to increased health care and economic burden. Exercise has shown promise over recent years as a mode of rehabilitation that alleviates multiple TBI symptoms; but there is a lack of controlled large-scale studies and limited research into the underlying mechanisms. This critical review draws from animal and human studies on exercise immunology to speculate on possible mechanisms that could underlie beneficial outcomes of exercise after TBI...

Kidney transplantations are seen to be a double-edge sword. Transplantations help to partially restore renal function, however there are a number of health-related co-morbidities associated with transplantation. Cardiovascular disease (CVD), malignancy and infections all limit patient and graft survival. Immunosuppressive medications alter innate and adaptive immunity and can result in immune dysfunction. Over suppression of the immune system can result in infections whereas under suppression can result in graft rejection...

BACKGROUND: The term immunometabolism describes cellular and molecular metabolic processes that control the immune system and the associated immune responses. Acute exercise and regular physical activity have a substantial influence on the metabolism and the immune system, so that both processes are closely associated and influence each other bidirectionally. SCOPE OF REVIEW: We limit the review here to focus on metabolic phenotypes and metabolic plasticity of T cells and macrophages to describe the complex role of acute exercise stress and regular physical activity on these cell types...

Despite evidence that monocyte migration is accentuated by central adiposity, the impact of physical activity (PA) and exercise, particularly in the post-prandial state, on limiting migration are not established. We hypothesised that PA and a single bout of walking exercise would be associated with reduced ex vivo monocyte tethering and migration in middleaged males with central obesity (CO). Objective levels of PA were measured for 7 days in lean males (LE, N=12, mean (SD) age 39 (10) years, waist circumference 81...

PURPOSE: Ageing is associated with alterations in the immune system as well as with alterations of the circadian rhythm. Immune cells show rhythmicity in execution of their tasks. Chronic inflammation (inflammaging), which is observed in the elderly, is mitigated by lifelong exercise. The aimed this study was to determine the acute effect of a maximal exercise test on clock genes, regulatory proteins and cytokine expression, and evaluate the effect of lifelong exercise on the expression of clock genes in subpopulations of effector-memory (EM) CD4+ and CD8+T cells and the association of these processes with the inflammatory profile...

BACKGROUND: Toll-like receptors (TLRs) are a family of transmembrane pattern recognition receptors that are mainly expressed on immune cells. Recognition of various exogenous and endogenous molecular patterns activates the TLR signalling cascade, which orchestrates an inflammatory immune response. Dysfunctional immune responses, including aberrant TLR signalling, are increasingly implicated in the associations between sedentarism, chronic low-grade systemic inflammation and various non-communicable diseases...

Many of the exercise-related health-promoting effects are attributed to beneficial immunomodulation. The restoration of immune homeostasis is context-dependent, meaning either to increase anti-inflammatory signaling to counteract disease progression of non-communicable (auto)inflammatory diseases or to enhance (local) activity of proinflammatory immune cells to slow down or inhibit cancer progression. Regulatory CD4+ T cells (Tregs) represent the main regulatory component of the adaptive immune system that fine-tunes inflammatory responses, keeps them in check and prevents long-lasting autoimmunity...

Numerous epidemiological studies have shown the existence of a relationship between exercise and reduced risk of different types of cancer. In vitro studies have identified a direct effect of exercise-conditioned human serum on cancer cell lines of the lung, breast, prostate, and colon. The aim of this systematic review with meta-analysis (SRM) was to estimate the magnitude of the effect that exercise-conditioned human serum produced on the viability of cancer cell cultures. The design followed the PRISMA guidelines and the TREND statement to assess the quality of information (QoI) in each study...

The hypothalamus plays a critical role in the control of food consumption and energy expenditure. Fatty diets can elicit an inflammatory response in specific hypothalamic cells, including astrocytes, tanycytes, and microglia, disrupting anorexigenic signals in region-specific hypothalamic neurons, contributing to overeating and body weight gain. In this study, we present an update regarding the knowledge of the effects of physical exercise on inflammatory signaling and circuits to control hunger in the hypothalamus in obesity conditions...

Atherosclerosis is a chronic inflammatory cardiovascular disease, which results from lipid accumulation in the blood vessel wall, forming a plaque, and ultimately restricting blood flow. The immune system plays a vital role in progression to plaque rupture. While recent evidence clearly indicates the anti-inflammatory function of regular exercise, the mechanisms by which regular exercise can modulate its pathophysiology is not well understood. In this review, we discuss how regular exercise can lower systemic inflammation directly via modulation of the immune system or indirectly via altered myokine concentrations and metabolites...

BACKGROUND: Regular exercise, particularly moderate-intensity continuous training (MICT), can improve immune function. Natural killer (NK) cells, a subset of lymphocytes that react to infections, are the most responsive innate immune cells to exercise, but the mechanisms underlying this are poorly understood. A type of exercise training that is gaining popularity in recent years is high-intensity interval training (HIIT), but how it affects NK cells is largely unknown. In fact, intense exercise has been traditionally viewed as a potential stressor to immune homeostasis...