Exercise enhances wound healing and prevents cancer progression during aging by targeting macrophage polarity

Non-coding RNAs in exercise immunology: A systematic review

Regular physical exercise has been recognized as a potent modulator of immune function, with its effects including enhanced immune surveillance, reduced inflammation, and improved overall health. While strong evidence exists that physical exercise affects the specific expression and activity of non-coding RNAs (ncRNAs) also involved in immune system regulation, heterogeneity in individual study designs and analyzed exercise protocols exists, and a condensed list of functional, exercise-dependent ncRNAs with known targets in the immune system is missing from the literature. A systematic review and qualitative analysis was used to identify and categorize ncRNAs participating in immune modulation by physical exercise. Two combined approaches were used: (a) a systematic literature search for "ncRNA and exercise immunology", (b) and a database search for microRNAs (miRNAs) (miRTarBase and DIANA-Tarbase v8) aligned with known target genes in the immune system based on the Reactome database, combined with a systematic literature search for "ncRNA and exercise". Literature searches were based on PubMed, Web of Science, and SPORTDiscus; and miRNA databases were filtered for targets validated by in vitro experimental data. Studies were eligible if they reported on exercise-based interventions in healthy humans. After duplicate removal, 95 studies were included reporting on 164 miRNAs, which were used for the qualitative synthesis. Six studies reporting on long-noncoding RNAs (lncRNAs) or circular RNAs were also identified. Results were analyzed using ordering tables that included exercise modality (endurance/resistance exercise), acute or chronic interventions, as well as the consistency in reported change between studies. Evaluation criteria were defined as "validated" with 100% of ≥3 independent studies showing identical direction of regulation, "plausible" (≥80%), or "suggestive" (≥70%). For resistance exercise, upregulation of miR-206 was validated while downregulation of miR-133a appeared plausible. For endurance exercise, 15 miRNAs were categorized as validated, with 12 miRNAs being consistently elevated and 3 miRNAs being downregulated, most of them after acute exercise training. In conclusion, our approach provides evidence that miRNAs play a major role in exercise-induced effects on the innate and adaptive immune system by targeting different pathways affecting immune cell distribution, function, and trafficking as well as production of (anti-)inflammatory cytokines. miRNAs miR-15, miR-29c, miR-30a, miR-142/3, miR-181a, and miR-338 emerged as key players in mediating the immunomodulatory effects of exercise predominantly after acute bouts of endurance exercise.

New Approaches in Heart Research: Prevention Instead of Cardiomyoplasty?

Cardiovascular diseases are the leading cause of death in industrialized nations. Due to the high number of patients and expensive treatments, according to the Federal Statistical Office (2017) in Germany, cardiovascular diseases account for around 15% of total health costs. Advanced coronary artery disease is mainly the result of chronic disorders such as high blood pressure, diabetes, and dyslipidemia. In the modern obesogenic environment, many people are at greater risk of being overweight or obese. The hemodynamic load on the heart is influenced by extreme obesity, which often leads to myocardial infarction (MI), cardiac arrhythmias, and heart failure. In addition, obesity leads to a chronic inflammatory state and negatively affects the wound-healing process. It has been known for many years that lifestyle interventions such as exercise, healthy nutrition, and smoking cessation drastically reduce cardiovascular risk and have a preventive effect against disorders in the healing process. However, little is known about the underlying mechanisms, and there is significantly less high-quality evidence compared to pharmacological intervention studies. Due to the immense potential of prevention in heart research, the cardiologic societies are calling for research work to be intensified, from basic understanding to clinical application. The topicality and high relevance of this research area are also evident from the fact that in March 2018, a one-week conference on this topic with contributions from top international scientists took place as part of the renowned "Keystone Symposia" ("New Insights into the Biology of Exercise"). Consistent with the link between obesity, exercise, and cardiovascular disease, this review attempts to draw lessons from stem-cell transplantation and preventive exercise. The application of state-of-the-art techniques for transcriptome analysis has opened new avenues for tailoring targeted interventions to very individual risk factors.

Physical exercise, health, and disease treatment: The role of macrophages

Subclinical inflammation is linked to comorbidities and risk factors, consolidating the diagnosis of chronic non-communicable diseases, such as insulin resistance, atherosclerosis, hepatic steatosis, and some types of cancer. In this context, the role of macrophages is highlighted as a marker of inflammation as well as for the high power of plasticity of these cells. Macrophages can be activated in a wide range between classical or proinflammatory, named M1, and alternative or anti-inflammatory, also known as M2 polarization. All nuances between M1 and M2 macrophages orchestrate the immune response by secreting different sets of chemokines, while M1 cells promote Th1 response, the M2 macrophages recruit Th2 and Tregs lymphocytes. In turn, physical exercise has been a faithful tool in combating the proinflammatory phenotype of macrophages. This review proposes to investigate the cellular and molecular mechanisms in which physical exercise can help control inflammation and infiltration of macrophages within the non-communicable diseases scope. During obesity progress, proinflammatory macrophages predominate in adipose tissue inflammation, which reduces insulin sensitivity until the development of type 2 diabetes, progression of atherosclerosis, and diagnosis of non-alcoholic fatty liver disease. In this case, physical activity restores the balance between the proinflammatory/anti-inflammatory macrophage ratio, reducing the level of meta-inflammation. In the case of cancer, the tumor microenvironment is compatible with a high level of hypoxia, which contributes to the advancement of the disease. However, exercise increases the level of oxygen supply, favoring macrophage polarization in favor of disease regression.

Modulation of the Circulating Extracellular Vesicles in Response to Different Exercise Regimens and Study of Their Inflammatory Effects

Exercise-released extracellular vesicles (EVs) are emerging as a novel class of exerkines that promotes systemic beneficial effects. However, slight differences in the applied exercise protocols in terms of mode, intensity and duration, as well as the need for standardized protocols for EV isolation, make the comparison of the studies in the literature extremely difficult. This work aims to investigate the EV amount and EV-associated miRNAs released in circulation in response to different physical exercise regimens. Healthy individuals were subjected to different exercise protocols: acute aerobic exercise (AAE) and training (AT), acute maximal aerobic exercise (AMAE) and altitude aerobic training (AAT). We found a tendency for total EVs to increase in the sedentary condition compared to trained participants following AAE. Moreover, the cytofluorimetric analysis showed an increase in CD81⁺/SGCA⁺/CD45^- EVs in response to AAE. Although a single bout of moderate/maximal exercise did not impact the total EV number, EV-miRNA levels were affected as a result. In detail, EV-associated miR-206, miR-133b and miR-146a were upregulated following AAE, and this trend appeared intensity-dependent. Finally, THP-1 macrophage treatment with exercise-derived EVs induced an increase of the mRNAs encoding for IL-1β, IL-6 and CD163 using baseline and immediately post-exercise EVs. Still, 1 h post-exercise EVs failed to stimulate a pro-inflammatory program. In conclusion, the reported data provide a better understanding of the release of circulating EVs and their role as mediators of the inflammatory processes associated with exercise.

Moderate exercise relieves fluoride-induced liver and kidney inflammatory responses through the IKKβ/NFκB pathway

With the intensification of environmental pollution, the content of fluoride is increasing in human and animal living environments. Long-term fluoride exposure can cause damage to the liver and kidney, which are the main sites for fluoride metabolism, storage and removal. Moreover, exercise often accompanies the entire process of fluoride exposure in humans and animals. However, the mechanism of exercise on fluoride-induced liver and kidney injury remains unclear. Hence, we established a fluoride exposure and/or exercise mouse model to explore the influence of exercise on fluoride-induced liver and kidney inflammation and the potential mechanism. The results showed that fluoride caused obvious structural and functional damage and the notable recruitment of immunocytes in the liver and kidney. In addition, fluoride increased the levels of IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12, IL-13, IL-21, TNF-α, and TGF-β but decreased the ratio of IFN-γ/IL-4 and IL-2/IL-10, which indicated that fluoride disturbed the inflammatory balance and caused hepatonephritis. In addition, the expression levels of IKKβ and NFκB were increased, and the expression of IκBα was decreased after fluoride exposure, indicating that fluoride activated the IKKβ/NFκB pathway. In summary, long-term moderate treadmill exercise relieved fluoride-induced liver and kidney inflammatory responses through the IKKβ/NFκB pathway, and exercise can be used to prevent fluoride-induced liver and kidney damage.

The effect of resistance exercise on the immune cell function in humans: A systematic review

BACKGROUND

Resistance exercise is beneficial for the immune system, including decreased susceptibility to infections and improved effectiveness of vaccinations. This review aims to provide a systematic analysis of the literature regarding the impact of resistance exercise on immune cells in the blood circulation.

MATERIALS AND METHODS

The protocol of this review followed the PRISMA guidelines and registered in PROSPERO (ID: CRD42020157834). PubMed and Web-of-Science were systematically searched for relevant articles. Outcomes were divided into two categories: 1) inflammatory gene expression or secretion of inflammation-related cytokines and 2) other aspects such as cell migration, proliferation, apoptosis, phagocytosis, and redox status.

RESULTS

Thirty intervention studies were included in this review, of which 11 articles were randomized controlled trials and six non-randomized controlled trials. Although only resistance exercise interventions were included, there was a high heterogeneity regarding specific exercise modalities. The most frequently studied outcome measures were the gene and protein expression levels in peripheral blood mononuclear cells (PBMC). This review reveals that already one acute exercise bout activates the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway in PBMC. Although resistance exercise induces an acute cytosolic oxidative stress response, the antioxidant enzyme expression is improved after resistance training period. Natural killer cell activity increases in older but decreases in younger adults immediately after a resistance exercise bout. Moreover, resistance exercise improves neutrophil phagocytic activity. Finally, effects on lymphocyte proliferation remain unclear.

CONCLUSIONS

The results of this systematic review demonstrate that resistance exercise has beneficial effects on several aspects of immune cell function both in young and older individuals. Acute changes in immune cell function occur already after a single bout of resistance exercise. However, regular resistance training during several weeks seems necessary to obtain beneficial adaptations that can be related to better immunity and reduced inflammation. The effects documented in this review confirm the beneficial effects of resistance exercise in young as well as older persons on the immune cell function.

An Activity Tracker-Guided Physical Activity Program for Patients Undergoing Radiotherapy: Protocol for a Prospective Phase III Trial (OnkoFit I and II Trials)

Background

The positive impact that physical activity has on patients with cancer has been shown in several studies over recent years. However, supervised physical activity programs have several limitations, including costs and availability. Therefore, our study proposes a novel approach for the implementation of a patient-executed, activity tracker–guided exercise program to bridge this gap.

Objective

Our trial aims to investigate the impact that an activity tracker–guided, patient-executed exercise program for patients undergoing radiotherapy has on cancer-related fatigue, health-related quality of life, and preoperative health status.

Methods

Patients receiving postoperative radiotherapy for breast cancer (OnkoFit I trial) or neoadjuvant, definitive, or postoperative treatment for other types of solid tumors (OnkoFit II trial) will be randomized (1:1:1) into 3-arm studies. Target accrual is 201 patients in each trial (50 patients per year). After providing informed consent, patients will be randomized into a standard care arm (arm A) or 1 of 2 interventional arms (arms B and C). Patients in arms B and C will wear an activity tracker and record their daily step count in a diary. Patients in arm C will receive personalized weekly targets for their physical activity. No further instructions will be given to patients in arm B. The target daily step goals for patients in arm C will be adjusted weekly and will be increased by 10% of the average daily step count of the past week until they reach a maximum of 6000 steps per day. Patients in arm A will not be provided with an activity tracker. The primary end point of the OnkoFit I trial is cancer-related fatigue at 3 months after the completion of radiotherapy. This will be measured by the Functional Assessment of Chronic Illness Therapy-Fatigue questionnaire. For the OnkoFit II trial, the primary end point is the overall quality of life, which will be assessed with the Functional Assessment of Cancer Therapy-General sum score at 6 months after treatment to allow for recovery after possible surgery. In parallel, blood samples from before, during, and after treatment will be collected in order to assess inflammatory markers.

Results

Recruitment for both trials started on August 1, 2020, and to date, 49 and 12 patients have been included in the OnkoFit I and OnkoFit II trials, respectively. Both trials were approved by the institutional review board prior to their initiation.

Conclusions

The OnkoFit trials test an innovative, personalized approach for the implementation of an activity tracker–guided training program for patients with cancer during radiotherapy. The program requires only a limited amount of resources.

Trial Registration

ClinicalTrials.gov NCT04506476; https://clinicaltrials.gov/ct2/show/NCT04506476. ClinicalTrials.gov NCT04517019; https://clinicaltrials.gov/ct2/show/NCT04517019.

International Registered Report Identifier (IRRID)

DERR1-10.2196/28524

Integrated Multiplex Sensing Bandage for In Situ Monitoring of Early Infected Wounds

Infection, the most common complication of chronic wounds, has placed tremendous burden on patients and society. Existing care strategies could hardly reflect in situ wound status, resulting in overly aggressive or conservative therapeutic options. Multiplexed tracking of wound markers to obtain diagnostic information in a more accurate way is highly promising and in great demand for the emerging development of personalized medicine. Here, an integrated multiplex sensing bandage (MSB) system, including a multiplex sensor array (MSA), a corresponding flexible circuit, and a mobile application, was developed for real-time monitoring of sodium, potassium, calcium, pH, uric acid, and temperature indicators in the wound site to provide a quantitative diagnostic basis. The MSB was optimized for wound-oriented management applications, which exhibits a broad linear response, excellent selectivity, temporal stability, mechanical stability, reproducibility, and reliable signal transmission performance on the aforementioned physiological indicators. The results of in vivo experiments demonstrate that the MSA is capable of real-time monitoring of actual wounds as well as early prediction of infection. The results ultimately point to the potential clinical applicability of the MSB, which might benefit the quantifications of the complexity and diversity of the wound healing process. This work provides a unique strategy that holds promise for broad application in optimizing wound management and even coping with other diseases.

Should weight-bearing activity be reduced during healing of plantar diabetic foot ulcers, even when using appropriate offloading devices?

Physical activity is an essential part of general health and diabetes management. However, recommending weight-bearing physical activity for people with plantar diabetic foot ulcers is controversial, even when gold standard offloading devices are used, as it is commonly thought to delay healing. We aimed to narratively review relevant studies investigating the relationship between plantar diabetic foot ulcer healing and weight-bearing activity, plantar pressure and device adherence. We defined relevant studies as those from two systematic reviews, along with those identified since using a similar updated Pubmed search strategy. We identified six studies. One study found that more daily steps were associated with worse ulcer healing, three found no significant association between steps and ulcer healing, and in two others the association was unclear. Thus, there is weak evidence for an inverse relationship between weight-bearing physical activity and plantar ulcer healing while utilizing offloading devices. We propose a Diabetic foot Offloading and Activity framework to guide future research to find the optimal balance between the positive and negative effects of weight-bearing activity in the context of foot ulcers. We hope such future studies will shed more conclusive light on the impact of weight-bearing activity on healing of plantar diabetic foot ulcers.

Benefits and Harms of Exercise Therapy for Patients With Diabetic Foot Ulcers: A Systematic Review

AIM

Exercise therapy is a core element in the treatment of diabetes, but the benefits and harms for patients with a diabetic foot ulcer (DFU) are unknown. We therefore aimed to systematically review the benefits on health-related quality of life (HRQoL) and harms of exercise therapy for patients with DFU.

METHODS

We searched 6 major databases. We performed citation and reference searches of included studies and contacted authors of ongoing trials. We included randomized controlled trials (RCTs) to assess potential benefits on HRQoL and harms of exercise therapy. Observational studies were included to identify potential harms of exercise therapy.

RESULTS

We included 10 published publications of 9 trials and results from 2 unpublished trials including a total of 281 individuals with DFUs receiving various forms of exercise therapy. Due to lack of HRQoL measurements and high heterogeneity, it was not possible to perform meta-analyses. Results on HRQoL was present in one unpublished study. Harms reported ranged from musculoskeletal problems, increased wound size, to amputation; however, no safe conclusions could be drawn from the available data due to high heterogeneity and risk of bias in the trials.

CONCLUSIONS/INTERPRETATION

Protective strategies are often preferred over therapeutic exercise that might have unforeseen consequences for patients over time. Based on the current literature, no evidence-based recommendations can be provided on the benefits and harms of exercise therapy for patients with DFUs. Well-conducted RCTs are needed to guide rehabilitation including detailed description of adverse events and an exercise program in a semisupervised or fully supervised setting.

Exercise influences the impact of polychlorinated biphenyl exposure on immune function

Polychlorinated biphenyls (PCBs) are environmental pollutants and endocrine disruptors, harmfully affecting reproductive, endocrine, neurological and immunological systems. This broad influence has implications for processes such as wound healing, which is modulated by the immunological response of the body. Conversely, while PCBs can be linked to diminished wound healing, outside of PCB pollution systems, exercise has been shown to accelerate wound healing. However, the potential for moderate intensity exercise to modulate or offset the harmful effects of a toxin like PCB are yet unknown. A key aim of the present study was to examine how PCB exposure at different doses (0, 100, 500, 1000 ppm i.p.) altered wound healing in exercised versus non-exercised subgroups of mice. We examined PCB effects on immune function in more depth by analyzing the concentrations of cytokines, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6) and granulocyte macrophage colony stimulating factor (GM-CSF) in these wounds inflicted by punch biopsy. Mice were euthanized at Day 3 or Day 5 after PCB injection (n = 3-6) and skin excised from the wound area was homogenized and analyzed for cytokine content. Results revealed that wound healing was not signficantly impacted by either PCB exposure or exercise, but there were patterns of delays in healing that depended on PCB dose. Changes in cytokines were also observed and depended on PCB dose and exercise experience. For example, IL-1β concentrations in Day 5 mice without PCB administration were 33% less in exercised mice than mice not exercised. However, IL-1β concentrations in Day 3 mice administered 100 ppm were 130% greater in exercised mice than not exercisedmice. Changes in the other measured cytokines varied with mainly depressions at lesser PCB doses and elevations at higher doses. Exercise had diverse effects on cytokine levels, but increased cytokine levels in the two greater doses. Explanations for these diverse effects include the use of young animals with more rapid wound healing rates less affected by toxin exposure, as well as PCB-mediated compensatory effects at specific doses which could actually enhance immune function. Future work should examine these interactions in more detail across a developmental time span. Understanding how manipulating the effects of exposure to environemntal contaminants using behavioral modification could be very useful in certain high risk populations or exposed individuals.

Inpatient admission following anterior cruciate ligament reconstruction is associated with higher postoperative complications

PURPOSE

To compare the occurrence of short-term postoperative complications between inpatient and outpatient anterior cruciate ligament reconstruction.

METHODS

The ACS National Surgical Quality Improvement Program (NSQIP) database was utilized to identify patients undergoing arthroscopic anterior cruciate ligament reconstruction (ACLR) from 2007 to 2017. A total of 18,052 patients were available for analysis following application of exclusion criteria. Patients were categorized based on location of surgery. Inpatients and outpatient ACLR groups were matched by demographics and preoperative laboratory values and differences in 30-day complication rates following surgery were assessed. Significance was set with alpha < 0.05.

RESULTS

From 2007 to 2017, there was an increasing frequency for outpatient ACLR (p < 0.001), while the incidence of inpatient ACLR remained largely constant (n.s). Groups were matched to include 1818 patients in each cohort. Within the first 30 days of surgery, patients in the inpatient ACLR group experienced significantly greater rates of superficial incisional SSI (0.6% vs 0.1%, p = 0.026) and composite surgical complications (0.6% vs 0.2%, p = 0.019), as well as a greater rate of reoperation (0.7% vs 0.2%, p = 0.029). Inpatient procedures also demonstrated a greater rate of deep surgical incisional SSI (0.2% vs 0.0%, n.s) and readmission to hospital (0.8% vs 0.7%, n.s).Outpatient ACLR procedures were also associated with a significantly greater relative value unit (RVU)/h compared with inpatient ACLRs (0.17 vs 0.14, p < 0.001).

CONCLUSIONS

Inpatient ACLR may have an increased risk of postoperative complications compared to outpatient ACLR during the short-term postoperative period. Although some patients may require admission post-operatively for medical and/or pain management, doing so is not necessarily without a degree of risk.

LEVEL OF EVIDENCE

III.

Wheel running predicts resilience to tumors in old mice

Aging intervention studies are hampered by the lack of predictive measures for determination of individuals at risk of age-associated chronic disease. Assessment of physical resilience could be informative in this regard, especially for age-related diseases such as cancer. Voluntary wheel running is a mildly stressful physical activity that is easily quantifiable in the mouse but has not been studied as a predictor of resistance to tumor invasiveness with increasing age. Male C57BL/6 mice in cohorts of 4, 12, 20, and 28 months of age were allowed access to a slanted in-cage running wheel for 3 days. Three months later, mice were injected subcutaneously with B16 melanoma tumor cells and followed for two weeks before harvesting. No relation was observed between running distance and tumor burden in the 4-month age group. The 12-month age group showed a trend, and the 20- and 28-month age groups showed a negative correlation (P < 0.05) between running distance and tumor burden. Mice in the 20-month age group that ran longer distances had lower tumor invasive scores compared to mice in the same age group that ran shorter distances. In conclusion, short term exercise capability could be a marker for resilience to cancer, and possibly other age-related disease conditions, in mice.

Rapamycin increases breast tumor burden in young wheel-running mice

Rapamycin is an immunosuppressive and anti-cancer drug recently shown to enhance healthy aging in animal models. Regular physical exercise is associated with healthy aging and reduced risk of age-related diseases, such as cancer. In order to test the combined effect of these approaches, mice with 4T1 breast cancer were fed rapamycin at 14 ppm and allowed access to voluntary running wheels. After 17 days of treatment, mice fed the rapamycin diet that ran showed a significant increase in tumor burden compared with mice that did not run (P = 0.017). Not only does this have implications for young breast cancer patients, but suggests that combining rapamycin and exercise as an anti-aging strategy at a young age might be contraindicated.

Effect of exercise on colorectal cancer prevention and treatment

In recent years, because of improved cancer screening, detection and treatment modalities, a rapid increase in the population of colorectal and other cancer survivors has been observed. The increasing population has justified the requirement of preventive strategies such as lifestyle modifications with regard to obesity, physical activity, diet and smoking. Physical activity may prevent approximately 15% of the colon cancers. Furthermore, several observational studies have demonstrated the efficacy and dose-dependent and anti-cancer effects of exercise on decreasing the mortality and risk of recurrence before and after the colorectal cancer (CRC) diagnosis. However, the required exercise dose, type and intensity are yet unclear. The results of randomised prospective studies are expected to determine the optimal amount, type and intensity of exercise and formulate the most appropriate exercise plan and guidelines, according to the requirements and comorbidities of the patients. In addition, recent studies have focused on the molecular and genetic mechanisms underlying the effect of physical activity on disease outcomes and recurrence rates. This review aimed to investigate the effects of physical activity and the biological basis of these effects in preventing the risk and recurrence of CRC and decreasing the hazards of cancer and cancer treatment.

Human kallikrein overexpression alleviates cardiac aging by alternatively regulating macrophage polarization in aged rats

Cardiac aging is characterized by myocardial hypertrophy, fibrosis, and diastolic dysfunction. Human kallikrein (hKLK1) protects against fibrosis in various pathogenic states. However, the effects of hKLK1 overexpression on cardiac aging-related fibrosis and the underlying mechanisms remain unknown. Moreover, the role of hKLK1 in regulating macrophage function leading to cardiac fibrosis has not been investigated. Thus, in this study, we determined the effects of hKLK1 on cardiac aging and explored the mechanisms through which hKLK1 regulated aging-related fibrosis. Echocardiographic measurements showed that aging caused significant alternations in cardiac morphology, hypertrophy, and fibrosis in rats, and hKLK1 overexpression protected against aging-induced cardiac dysfunction. Compared with wild-type hearts, the hKLK1 transgene decreased the expression of monocyte chemoattractant protein 1 and suppressed mitochondrial dysfunction and excess oxidative stress, leading to decreased recruitment and retention of alternatively activated (M2) macrophages and reduced secretion of profibrotic cytokines mediated by the TGF-β1-Smad3 signaling pathway in hearts of aging rats. Furthermore, these cardioprotective effects of hKLK1 overexpression were associated with the Janus kinase-signal transducer and activator of transcription 3 signaling pathway. H₂O₂-induced senescence promoted the differentiation of RAW264.7 cells into M2-type cells induced by IL-4 treatment. Bradykinin treatment relieved the migratory capacity of macrophages induced by H₂O₂. Thus, hKLK1 overexpression reduced cardiac fibrosis and improved aging-related cardiac dysfunction through reduced shift of macrophages to M2 macrophages, indicating that hKLK1 may alleviate aging-related cardiac dysfunction.-Hu, D., Dong, R., Yang, Y., Chen, Z., Tang, Y., Fu, M., Wang, D. W., Xu, X., Tu, L. Human kallikrein overexpression alleviates cardiac aging by alternatively regulating macrophage polarization in aged rats.

Macrophages in wound healing: activation and plasticity

Macrophages are critically involved in wound healing, from dampening inflammation to clearing cell debris and coordinating tissue repair. Within the wound, the complexity of macrophage function is increasingly recognized, with adverse outcomes when macrophages are inappropriately activated, such as in fibrosis or chronic non-healing wounds. Recent advances in in vivo and translational wound models, macrophage-specific deletions and new technologies to distinguish macrophage subsets, have uncovered the vast spectrum of macrophage activation and effector functions. Here, we summarize the main players in wound-healing macrophage activation and function, including cytokines, apoptotic cells, nucleotides and mechanical stimuli. We highlight recent studies demonstrating cooperation between these factors for optimal wound healing. Next, we describe recent technologies such as cell tracking and single-cell RNA-seq, which have uncovered remarkable plasticity and heterogeneity in blood-derived or tissue-resident macrophages and discuss the implications for wound healing. Lastly, we evaluate macrophage dysfunction in aberrant wound healing that occurs in aging, diabetes and fibrosis. A better understanding of the longevity and plasticity of wound-healing macrophages, and identification of unique macrophage subsets or specific effector molecules in wound healing, would shed light on the therapeutic potential of manipulating macrophage function for optimal wound healing.

Autophagy as a Therapeutic Target to Enhance Aged Muscle Regeneration

Skeletal muscle has remarkable regenerative capacity, relying on precise coordination between resident muscle stem cells (satellite cells) and the immune system. The age-related decline in skeletal muscle regenerative capacity contributes to the onset of sarcopenia, prolonged hospitalization, and loss of autonomy. Although several age-sensitive pathways have been identified, further investigation is needed to define targets of cellular dysfunction. Autophagy, a process of cellular catabolism, is emerging as a key regulator of muscle regeneration affecting stem cell, immune cell, and myofiber function. Muscle stem cell senescence is associated with a suppression of autophagy during key phases of the regenerative program. Macrophages, a key immune cell involved in muscle repair, also rely on autophagy to aid in tissue repair. This review will focus on the role of autophagy in various aspects of the regenerative program, including adult skeletal muscle stem cells, monocytes/macrophages, and corresponding age-associated dysfunction. Furthermore, we will highlight rejuvenation strategies that alter autophagy to improve muscle regenerative function.

Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan

Epidemiological evidence indicates that regular physical activity and/or frequent structured exercise reduces the incidence of many chronic diseases in older age, including communicable diseases such as viral and bacterial infections, as well as non-communicable diseases such as cancer and chronic inflammatory disorders. Despite the apparent health benefits achieved by leading an active lifestyle, which imply that regular physical activity and frequent exercise enhance immune competency and regulation, the effect of a single bout of exercise on immune function remains a controversial topic. Indeed, to this day, it is perceived by many that a vigorous bout of exercise can temporarily suppress immune function. In the first part of this review, we deconstruct the key pillars which lay the foundation to this theory-referred to as the "open window" hypothesis-and highlight that: (i) limited reliable evidence exists to support the claim that vigorous exercise heightens risk of opportunistic infections; (ii) purported changes to mucosal immunity, namely salivary IgA levels, after exercise do not signpost a period of immune suppression; and (iii) the dramatic reductions to lymphocyte numbers and function 1-2 h after exercise reflects a transient and time-dependent redistribution of immune cells to peripheral tissues, resulting in a heightened state of immune surveillance and immune regulation, as opposed to immune suppression. In the second part of this review, we provide evidence that frequent exercise enhances-rather than suppresses-immune competency, and highlight key findings from human vaccination studies which show heightened responses to bacterial and viral antigens following bouts of exercise. Finally, in the third part of this review, we highlight that regular physical activity and frequent exercise might limit or delay aging of the immune system, providing further evidence that exercise is beneficial for immunological health. In summary, the over-arching aim of this review is to rebalance opinion over the perceived relationships between exercise and immune function. We emphasize that it is a misconception to label any form of acute exercise as immunosuppressive, and, instead, exercise most likely improves immune competency across the lifespan.

Inflammatory cytokines and immune system modulation by aerobic versus resisted exercise training for elderly

Background

Aging is characterized with immunosenescence associated with a hyper-inflammatory state, characterized by elevated circulating levels of pro-inflammatory mediators. Physical exercise is a potential strategy for improving the immune system dysfunction and chronic inflammation that accompanies aging. However, there is a need to differentiate between aerobic and resistance exercise training regarding human immune system and systemic inflammation among the elderly Saudi population.

Objective

The aim of this study was to compare the impact of 6 months of aerobic versus resisted exercise training on inflammatory cytokines and immune system response among elderly.

Material and methods

Sixty previously sedentary elderly subjects participated in this study, their age ranged from 61–66 years. All Subjects were randomly assigned to supervised aerobic exercise intervention group (group A, n=40) or resistance exercise group (group B, n=40). Number of CD3⁺,CD4⁺,CD8⁺ T cells count and CD4/CD8 ratio were quantified, IL-6, TNF-α and IL10 were measured before and after 6 months, at the end of the study.

Results

The mean values of CD3⁺, CD4⁺ and CD8⁺ T cells count and IL-10 were significantly increased, whereas the mean values of CD4/CD8 ratio, IL-6 and TNF-α were significantly decreased in group (A) and group (B). Also; there were significant differences between mean levels of the investigated parameters in group (A) and group (B) after treatment.

Conclusion

The current study provides evidence that aerobic exercise is more appropriate in modulating the immune system and inflammatory markers among the elderly population.

Exercise and the Tumor Microenvironment: Potential Therapeutic Implications

An imbalance in oxygen delivery to demand in solid tumors results in local areas of hypoxia leading to poor prognosis for the patient. We hypothesize that aerobic exercise increases tumor blood flow, recruits previously nonperfused tumor blood vessels, and thereby augments blood-tumor O2 transport and diminishes tumor hypoxia. When combined with conventional anticancer treatments, aerobic exercise can significantly improve the outcomes for several types of cancers.

Preliminary Evaluation of a Cycling Cleat Designed for Diabetic Foot Ulcers

BACKGROUND

Offloading devices for diabetic foot ulcers (DFU) generally restrict exercise. In addition to traditional health benefits, exercise could benefit DFU by increasing blood flow and acting as thermotherapy. This study functionally evaluated a cycling cleat designed for forefoot DFU.

METHODS

Fifteen individuals at risk of developing a DFU used a recumbent stationary bicycle to complete one 5-minute cycling bout with the DFU cleat on their study foot and one 5-minute bout without it. Foot stress was evaluated by plantar pressure insoles during cycling. Laser Doppler perfusion monitored blood flow to the hallux. Infrared photographs measured foot temperature before and after each cycling bout.

RESULTS

The specialized cleat significantly reduced forefoot plantar pressure (9.9 kPa versus 62.6 kPa, P < .05) and pressure time integral (15.4 versus 76.4 kPa*sec, P < .05). Irrespective of footwear condition, perfusion to the hallux increased (3.97 ± 1.2 versus 6.9 ± 1.4 tissue perfusion units, P < .05) after exercise. Infrared images revealed no changes in foot temperature.

CONCLUSIONS

The specialized cleat allowed participants to exercise with minimal forefoot stress. The observed increase in perfusion suggests that healing might improve if patients with active DFU were to use the cleat. Potential thermotherapy for DFU was not supported by this study. Evaluation of the device among individuals with active DFU is now warranted.

Does Regular Exercise Counter T Cell Immunosenescence Reducing the Risk of Developing Cancer and Promoting Successful Treatment of Malignancies?

Moderate intensity aerobic exercise training or regular physical activity is beneficial for immune function. For example, some evidence shows that individuals with an active lifestyle exhibit stronger immune responses to vaccination compared to those who are inactive. Encouragingly, poor vaccine responses, which are characteristic of an ageing immune system, can be improved by single or repeated bouts of exercise. In addition, exercise-induced lymphocytosis, and the subsequent lymphocytopenia, is thought to facilitate immune surveillance, whereby lymphocytes search tissues for antigens derived from viruses, bacteria, or malignant transformation. Aerobic exercise training is anti-inflammatory and is linked to lower morbidity and mortality from diseases with infectious, immunological, and inflammatory aetiologies, including cancer. These observations have led to the view that aerobic exercise training might counter the age-associated decline in immune function, referred to as immunosenescence. This article summarises the aspects of immune function that are sensitive to exercise-induced change, highlighting the observations which have stimulated the idea that aerobic exercise training could prevent, limit, or delay immunosenescence, perhaps even restoring aged immune profiles. These potential exercise-induced anti-immunosenescence effects might contribute to the mechanisms by which active lifestyles reduce the risk of developing cancer and perhaps benefit patients undergoing cancer therapy.

Paracrine cross-talk between skeletal muscle and macrophages in exercise by PGC-1α-controlled BNP

Activation of resident and infiltrating immune cells is a central event in training adaptation and other contexts of skeletal muscle repair and regeneration. A precise orchestration of inflammatory events in muscle fibers and immune cells is required after recurrent contraction-relaxation cycles. However, the mechanistic aspects of this important regulation remain largely unknown. We now demonstrate that besides a dominant role in controlling cellular metabolism, the peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) also has a profound effect on cytokine expression in muscle tissue. Muscle PGC-1α expression results in activation of tissue-resident macrophages, at least in part mediated by PGC-1α-dependent B-type natriuretic peptide (BNP) production and secretion. Positive effects of exercise in metabolic diseases and other pathologies associated with chronic inflammation could accordingly involve the PGC-1α-BNP axis and thereby provide novel targets for therapeutic approaches.

Advanced Age Alters Monocyte and Macrophage Responses

SIGNIFICANCE

With the growing population of baby boomers, there is a great need to determine the effects of advanced age on the function of the immune system. Recent Advances: It is universally accepted that advanced age is associated with a chronic low-grade inflammatory state that is referred to as inflamm-aging, which alters the function of both immune and nonimmune cells. Mononuclear phagocytes play a central role in both the initiation and resolution of inflammation in multiple organ systems and exhibit marked changes in phenotype and function in response to environmental cues, including the low levels of pro-inflammatory mediators seen in the aged.

CRITICAL ISSUES

Although we know a great deal about the function of immune cells in young adults and there is a growing body of literature focusing on aging of the adaptive immune system, much less is known about the impact of age on innate immunity and the critical role of the mononuclear phagocytes in this process.

FUTURE DIRECTIONS

In this article, there is a focus on the tissue-specific monocyte and macrophage subsets and how they are altered in the aged milieu, with the hope that this compilation of observations will spark an expansion of research in the field. Antioxid. Redox Signal. 25, 805-815.

Dynamic impact of brief electrical nerve stimulation on the neural immune axis-polarization of macrophages toward a pro-repair phenotype in demyelinated peripheral nerve

Demyelinating peripheral nerves are infiltrated by cells of the monocyte lineage, including macrophages, which are highly plastic, existing on a continuum from pro-inflammatory M1 to pro-repair M2 phenotypic states. Whether one can therapeutically manipulate demyelinated peripheral nerves to promote a pro-repair M2 phenotype remains to be elucidated. We previously identified brief electrical nerve stimulation (ES) as therapeutically beneficial for remyelination, benefits which include accelerated clearance of macrophages, making us theorize that ES alters the local immune response. Thus, the impact of ES on the immune microenvironment in the zone of demyelination was examined. Adult male rat tibial nerves were focally demyelinated via 1% lysophosphatidyl choline (LPC) injection. Five days later, half underwent 1 hour 20 Hz sciatic nerve ES proximal to the LPC injection site. ES had a remarkable and significant impact, shifting the macrophage phenotype from predominantly pro-inflammatory/M1 toward a predominantly pro-repair/M2 one, as evidenced by an increased incidence of expression of M2-associated phenotypic markers in identified macrophages and a decrease in M1-associated marker expression. This was discernible at 3 days post-ES (8 days post-LPC) and continued at the 5 day post-ES (10 days post-LPC) time point examined. ES also affected chemokine (C-C motif) ligand 2 (CCL2; aka MCP-1) expression in a manner that correlated with increases and decreases in macrophage numbers observed in the demyelination zone. The data establish that briefly increasing neuronal activity favorably alters the immune microenvironment in demyelinated nerve, rapidly polarizing macrophages toward a pro-repair phenotype, a beneficial therapeutic concept that may extend to other pathologies. GLIA 2016;64:1546-1561.

Prior regular exercise improves clinical outcome and reduces demyelination and axonal injury in experimental autoimmune encephalomyelitis

Although previous studies have shown that forced exercise modulates inflammation and is therapeutic acutely for experimental autoimmune encephalomyelitis (EAE), the long-term benefits have not been evaluated. In this study, we investigated the effects of preconditioning exercise on the clinical and pathological progression of EAE. Female C57BL/6 mice were randomly assigned to either an exercised (Ex) or unexercised (UEx) group and all of them were induced for EAE. Mice in the Ex group had an attenuated clinical score relative to UEx mice throughout the study. At 42 dpi, flow cytometry analysis showed a significant reduction in B cells, CD4(+) T cells, and CD8(+) T cells infiltrating into the spinal cord in the Ex group compared to UEx. Ex mice also had a significant reduction in myelin damage with a corresponding increase in proteolipid protein expression. Finally, Ex mice had a significant reduction in axonal damage. Collectively, our study demonstrates for the first time that a prolonged and forced preconditioning protocol of exercise improves clinical outcome and attenuates pathological hallmarks of EAE at chronic disease. In this study, we show that a program of 6 weeks of preconditioning exercise promoted a significant reduction of cells infiltrating into the spinal cord, a significant reduction in myelin damage and a significant reduction in axonal damage in experimental autoimmune encephalomyelitis (EAE) mice at 42 dpi. Collectively, our study demonstrates for the first time that a preconditioning protocol of exercise improves clinical outcome and attenuates pathological hallmarks of EAE at chronic disease.