Sweet regulation - The emerging immunoregulatory roles of hexoses

BACKGROUND

It is widely acknowledged that dietary habits have profound impacts on human health and diseases. As the most important sweeteners and energy sources in human diets, hexoses take part in a broad range of physiopathological processes. In recent years, emerging evidence has uncovered the crucial roles of hexoses, such as glucose, fructose, mannose, and galactose, in controlling the differentiation or function of immune cells.

AIM OF REVIEW

Herein, we reviewed the latest research progresses in the hexose-mediated modulation of immune responses, provided in-depth analyses of the underlying mechanisms, and discussed the unresolved issues in this field.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Owing to their immunoregulatory effects, hexoses affect the onset and progression of various types of immune disorders, including inflammatory diseases, autoimmune diseases, and tumor immune evasion. Thus, targeting hexose metabolism is becoming a promising strategy for reversing immune abnormalities in diseases.

Empagliflozin improves kidney senescence induced by D-galactose by reducing sirt1-mediated oxidative stress

Sodium-glucose cotransporter-2 (SGLT-2) inhibitors have received widespread attention because of their significant protective effects on the kidney. Previous studies have shown that Sirt1, as which is an antiaging protein, is closely related to the maintenance of redox homeostasis. The goal of this study was to determine whether empagliflozin could ameliorate D-galactose-induced renal senescence in mice, and examine the possible mechanisms of Sirt1. We constructed a rapid ageing model in mice by administering D-galactose. An ageing model was constructed by treating cells with high glucose. Treadmill and Y-maze tests were used to assess exercise tolerance and learning memory ability. Pathologically stained sections were used to assess kidney injury. Tissue and cell senescence were evaluated by senescence-associated β-galactosidase staining. The expression levels of P16, SOD1, SOD2 and Sirt1 were detected by immunoblotting. D-gal-treated mice exhibited significant age-related changes, as measured by behavioural tests and ageing marker protein levels. empagliflozin alleviated these ageing manifestations. In addition, Sirt1, SOD1 and SOD2 levels were downregulated in model mice and upregulated by empagliflozin treatment. Empagliflozin had similar protective effects at the cellular level, and these effects were reduced by the Sirt1 inhibitor. Empagliflozin has an antiaging effect, which may be related to reducing Sirt1-mediated oxidative stress.

Beneficial effects of whey protein peptides on muscle loss in aging mice models

Aging-related muscle loss is a hallmark of aging and is the cause of some negative outcomes. An optimized diet and supplements have a positive effect in slowing down the process of muscle loss. D-galactose(d-gal) has been used widely to develop aging model. This study explored the beneficial effects of whey protein peptides (WPPs) on sarcopenia in d-gal-induced aging mice. A total of 72 SPF male C57BL/6N mice were used in this study. Sixty mice were modeled by injected intraperitoneally with d-gal (100 mg/kg body weight for 6 weeks), and the other 12 mice were used as control, and injected with the same amount of normal saline. After 6 weeks, the modeled mice were randomly divided into the model control group, whey protein group (1.5 g/kg^*bw), and three WPPs intervention groups (0.3 g/kg^*bw, 1.5 g/kg^*bw, 3.0 g/kg^*bw), according to serum malondialdehyde (MDA) level. The test samples were orally given to mice by daily garaged. During the 30 days intervention period, the model control group, whey protein group, and WPPs group continued receiving intraperitoneal injections of d-gal, whereas the control group continued receiving intraperitoneal injections of normal saline. The results showed that WPPs could significantly improve the grip strength of aged mice. WPPs could significantly increase lean mass of aged mice and increase muscle weight of gastrocnemius and extensor digitorum longus. WPPs could significantly increase the level of insulin-like growth factor-1 (IGF-1) and reduce level of interleukin (IL)-1, IL-6, tumor necrosis factor-alpha (TNF-α) in serum. WPPs could affect the muscle fiber size in d-gal-induced aging mice. Its specific mechanism may be related to the activation of IGF-1/Akt/mTOR protein synthesis signaling pathway and reduction of the level of inflammation. These results indicate that WPPs can improve aging-related sarcopenia. Compared with whey protein, WPPs supplement seems a better form for sarcopenia.

D-galactose induced dysfunction in mice hippocampus and the possible antioxidant and neuromodulatory effects of selenium

Aging is an ultimate reality that everyone has to face. D-galactose (D-gal) has been used extensively to develop aging model. Trace elements such as selenium (Se) have been used as a potential antioxidant for neuro-protection. The present work aims to develop therapeutic agents such as Se for the treatment of aging-induced neurological ailments such as anxiety, depression, and memory impairment. For this purpose, mice were treated with D-gal at a dose of 300 mg/ml/kg and various doses of Se (0.175 and 0.35mg/ml/kg) for 28 days. Behavioral tests were monitored after treatment days. After the behavioral assessment, mice were decapitated and their brains were collected. Hippocampi were removed from the brain for biochemical, neurochemical, and histopathological analysis. The present findings of behavioral analysis showed that D-gal-induced anxiety- and depression-like symptoms were inhibited by both doses of Se. D-gal-induced memory alteration was also prevented by repeated doses of Se (0.175 and 0.35mg/ml/kg). Biochemical analysis showed that D-gal-induced increase of oxidative stress and inflammatory markers and decrease of antioxidant enzymes and total protein contents in the hippocampus were prevented by Se administration. An increase in the activity of acetylcholinesterase was also diminished by Se. The neurochemical assessment showed that D-gal-induced increased serotonin metabolism and decreased acetylcholine levels in the hippocampus were restored by repeated treatment of Se. Histopathological estimations also exhibited; normalization of D-gal induced neurodegenerative changes. It is concluded that D-gal-induced dysfunction in mice hippocampus caused anxiety, depression, memory impairment, oxidative stress, neuro-inflammation, and histological alterations that were mitigated by Se via its antioxidant potential, anti-inflammatory property, and modulating capability of serotonergic and cholinergic functions.

Curcumin protects thymus against D-galactose-induced senescence in mice

Senescence-related decline of thymus affects immune function in the elderly population and contributes to the prevalence of many relevant diseases like cancer, autoimmune diseases, and other chronic diseases. In this study, we investigated the therapeutic effects of curcumin, an agent that could counter aging, and explored its optimal intake and the alteration of autoimmune regulator (Aire) after curcumin treatment in the D-galactose (D-gal)-induced accelerated aging mice. ICR mice were intraperitoneally injected with D-gal for 8 weeks to establish the accelerated aging model and given curcumin with 50, 100, and 200 mg/kg body weight per day by gavage, respectively, for 6 weeks. It indicated that the D-gal-treated mice developed structural changes in the thymi compared with the control group without D-gal and curcumin treatment. As the supplements of curcumin, it resulted in a restoration of the normal thymic anatomy with an increase of proliferating cells and a reduction of apoptotic cells in the thymi of the D-gal-induced aging model mice. Curcumin administration could also expand the expression level of Aire from mRNA level and protein level. The current study demonstrated that curcumin could ameliorate senescence-related thymus involution via upregulating Aire expression, suggesting that curcumin can rejuvenate senescence-associated alterations of thymus induced by D-gal accumulation.

Integration of lncRNA and mRNA profiles to reveal the protective effects of Codonopsis pilosula extract on the gastrointestinal tract of mice subjected to D‑galactose‑induced aging

Codonopsis pilosula is a type of traditional Chinese medicine that exerts an anti‑aging effect and can regulate the gastrointestinal (GI) system. The aim of the present study was to investigate the underlying molecular mechanisms responsible for the anti‑aging effects of Codonopsis pilosula in the GI tract of mice with D‑galactose‑induced aging. First, a successful mouse model of aging was established, and Codonopsis pilosula water extract was then used for treatment. The anti‑aging effects of Codonopsis pilosula on the GI tract were then detected from the perspectives of tissue structure, physiological function and cell ultrastructure. Finally, in order to explore the underlying molecular mechanisms, the expression profiles of lncRNAs and mRNAs in the stomach and intestine were examined using microarray technology. A total of 117 (41 lncRNAs and 76 mRNAs) and 168 (85 lncRNA sand 83 mRNAs) differentially expressed genes associated with the anti‑aging effects of Codonopsis pilosula were identified in the stomach and intestine, respectively. Through integrated analysis of the stomach and intestine, 4 hub RNAs, including 1 lncRNA (LOC105243318) and 3 mRNAs (Fam132a, Rorc and 1200016E24Rik) were identified, which may be associated with the anti‑aging effects of Codonopsis pilosula in the GI tract of aging mice. The Kyoto Encyclopedia of Genes and Genomes analysis revealed that the metabolic pathway was an important pathway underlying the anti‑aging effects of Codonopsis pilosula in the GI tract. On the whole, in the present study, 4 hub RNAs associated with these effects and their regulatory networks were found in the GI tract of aging mice. In addition, the metabolic pathway was found to play an important role in these anti‑aging effects in the GI tract.

miRNA-146a-5p mitigates stress-induced premature senescence of D-galactose-induced primary thymic stromal cells

Senescent thymic stromal cells (TSCs) producing senescence-associated secretory phenotype (SASP) may play a role at later phases of thymic involution. However, the etiology and mechanisms responsible for TSC senescence remain to be elucidated. In the present study, the effects of oxidative stress on TSCs and role of miRNA-146a-5p in stress-induced premature senescence (SIPS) were identified. D-galactose (D-gal) induced oxidative stress in primary TSCs and a limited cumulative oxidative stress induced premature senescence but not apoptosis of TSCs. miRNA-146a-5p overexpression can mitigate the SIPS by targeting tumor necrosis factor receptor-associated factor 6 (TRAF6) instead of increasing autophagy clearance. Furthermore, exogenous miRNA-146a-5p reversed the upregulation of chemokines including Cxcl5, pro-inflammatory cytokines, and antimicrobial peptides in TSCs with SIPS. In conclusion, the accumulated oxidative stress may be partially responsible for senescence in TSCs and modulation of miRNA-146a-5p may attenuate this process.

Integrative Analysis of Long Non-Coding RNAs (lncRNAs), miRNAs, and mRNA-Associated ceRNA Network in Lung Tissue of Aging Mice and Changes After Treatment with Codonopsis pilosula

Background

Codonopsis pilosula is a traditional Chinese medicine that has an anti-aging effect. However, the anti-aging effect of Codonopsis pilosula on the lungs remains largely unknown, and the molecular mechanism also needs to be further studied. Thus, we investigated the protective effect of Codonopsis pilosula on the lungs of aging mice, and explored the underlying molecular mechanism.

Material/Methods

We established an aging mouse model and then treated the mice with Codonopsis pilosula. Microarray analysis and bioinformatics methods were used to comprehensively analyze the lncRNA-miRNA-mRNA (ceRNA) network.

Results

Our results showed that we successfully established the aging mouse model. The microarray analysis showed that 138 lncRNAs, 128 mRNAs, and 7 miRNAs were significantly changed after aging, and 282 lncRNAs, 283 mRNAs, and 19 miRNAs were dysregulated after treatment with Codonopsis pilosula. To explore the signaling pathways involved, KEGG pathway analysis was performed. Compared with the ceRNA network in aging mice and after treatment with Codonopsis pilosula, we found that 3 mRNAs (Hif3a, Zbtb16, Plxna2) and 1 lncRNA (NONMMUT063872) were associated with the anti-aging effect of Codonopsis pilosula and they were validated by quantitative real-time polymerase chain reaction (qRT-PCR) analysis.

Conclusions

Our results showed that Codonopsis pilosula has a protective effect on the aging lung, and the ceRNA network plays an important role in the anti-aging effect of Codonopsis pilosula.