Effect of exercise-induced Neutrophil maturation on skeletal muscle repair in vitro.

Neutrophils as first line defender initiate a cascade of healing process immediately after muscle injury. At muscle injury site, neutrophils remove damaged muscle fibers and recruit other immune cells and these functions show in mature neutrophils. In the previous study, physical exercise can mediate neutrophils' functional changes such as phagocytosis and chemotaxis, though there is no research on how exercise-induced neutrophils contribute the muscle regeneration. In this present study, we investigated the maturation of neutrophils after 4 weeks of mouse treadmill exercise and assessed wound healing assay to evaluate whether treatment with exercise-activated neutrophils is effective for skeletal muscle repair in vitro. In the exercise group, significantly higher mRNA levels of maturation markers compared to the sedentary group and exercise-activated neutrophils improved wound healing of mouse muscle cells. To confirm at the human cell level, based on the well-known fact that exercise increases circulating cortisol levels, neutrophil-like cells were treated with dexamethasone (dHL60 + dex) as exercise mimetics. dHL60 + dex had significantly higher mRNA levels of neutrophil maturation marker and improved wound healing of human skeletal muscle cells compared to the control. These findings suggest that exercise affects neutrophil maturation and that exercise-induced neutrophils contribute to skeletal muscle repair in vitro.

Distinct effect of exercise modes on mood-related behavior in mice.

Exercise can afford several benefits to combat mood disorders in both rodents and humans. Engagement in various physical activities upregulates levels of neurotrophic factors in several brain regions and improves mental health. However, the type of exercise that regulates mood and the underlying mechanisms in the brain remain elusive. Herein, we performed two distinct types of exercise and RNA sequencing analyses to investigate the effect of exercise on mood-related behaviors and explain the distinct patterns of gene expression. Specifically, resistance exercise exhibited reduced immobility time in the forced swim test when compared with both no exercise and treadmill exercise (in the aerobic training [AT] group). Interestingly, anxiety-like behaviors in the open field and nest-building tests were ameliorated in the AT group when compared with those in the control group; however, this was not observed in the RT group. To elucidate the mechanism underlying these different behavioral changes caused by distinct exercise types, we examined the shift in the gene expression pattern in the hippocampus, a brain region that plays a critical role in regulating mood. We discovered that 38 and 40 genes were altered in the AT and RT groups, respectively, compared with the control group. Both exercises regulated 16 common genes. Compared with the control group, mitogen-activated protein kinase (MAPK) was enriched in the AT group and phosphatidylinositol-3-kinase (PI3K)/AKT and neurotrophin signaling pathways were enriched in the RT group, as determined by bioinformatics pathway analysis. PCR results revealed that Cebpß expression was increased in AT group, and Dcx expression was upregulated in both groups. Our findings indicate that different exercise types may exert substantially distinct effects on mood-like behaviors. Accordingly, appropriate types of exercise can be undertaken based on the mood disorder to be regulated.

Potential involvement of neutrophils on exercise effects in breast cancer malignancy.

PURPOSE: This review aimed to comprehensively explore and elucidate multifaceted neutrophils in breast cancer, particularly in the context of physical activity. Neutrophils play a critical role in the tumor microenvironment and systemic immune response, despite their short half-life and terminal differentiation. Through a thorough review of research related to changes in immunity in breast cancer during exercise, this review aims to provide comprehensive insights into immunological changes, especially focusing on neutrophils. Recognizing that much of the existing research has predominantly focused on T cells and nature killer (NK) cells, our review seeks to shift the spotlight toward understanding how exercise affects neutrophils, a less-explored but critical immune response component in breast cancer. METHODS: This study involved an extensive review of the literature (from 2000 to 2023) using the PubMed, Science Direct, and Google Scholar databases. The keywords chosen for the searches were "immune cells and exercise," "exercise and breast cancer," "tumor microenvironment and neutrophils," and "neutrophils and exercise and breast cancers." RESULTS: Neutrophils in the tumor microenvironment can exhibit distinct phenotypes and functions. These differences have yielded conflicting results regarding tumor progression. Exercise plays a positive role in breast cancer and alters the immune system. Physical activity can quantitatively and functionally regulate neutrophils under various conditions such as metabolic disruption or senescence. CONCLUSION: This short communication outlines exercise-induced neutrophil diversification and its role in breast cancer progression, both within and systemically within the tumor microenvironment. Exercise may provide benefits through the potential neutrophil involvement in breast cancer.