Niacin promotes revascularization and recovery of limb function in diet-induced obese mice with peripheral ischemia

Metabolomics analysis of anaphylactoid reactions induced by Xueshuantong injection in normal and immunocompromised mice

Background

Xueshuantong injection (Lyophilized) (XSTI) is widely used to treat cardiovascular and cerebrovascular diseases. However, anaphylactoid reactions (ARs) are frequently reported as one of its side effects, and the mechanisms of ARs and their relationship with the different immune status are still not well understood.

Purpose

This article aims to examine the sensitizing effect of XSTI, explore the impact of normal and immunocompromised states on ARs, and analyze AR-related metabolic pathways by metabolomics.

Methods

An immunocompromised mouse model was established through intraperitoneal injection of cyclophosphamide (CTX). Normal and immunocompromised mice were then treated with normal saline (NS), histamine (HIS), and XSTI, respectively. Behavioral responses, auricle blue staining, and Evans blue (EB) exudation were used as indices to evaluate the sensitization of XSTI on both normal and immunocompromised mice. Subsequently, ARs models with different immune statuses were established, and validated by measuring four serum indicators using enzyme-linked immunosorbent assay (ELISA). Finally, LC-MS metabolomics analysis was performed on mouse serum to evaluate the metabolic pathways.

Results

The intensity of ARs induced by XSTI in mice was found to increase with the administered dose, with normal mice exhibiting higher AR intensities compared to immunocompromised mice. Metabolomic analysis revealed significant metabolic changes in XSTI-treated mice. The metabolic pathways predicted from these different metabolites include biotin metabolism, histidine metabolism, glycerolipid metabolism, bile secretion, arachidonic acid metabolism, sphingolipid metabolism, niacin and nicotinamide metabolism, tryptophan metabolism, steroid biosynthesis, and arginine and proline metabolism.

Conclusion

Research indicated that the sensitization of XSTI is dose-dependent, and mice with weakened immune functions exhibit lower sensitivity. Through metabolomics research, the differential metabolites in mice were analyzed, and the metabolic pathways inducing ARs were predicted. This study offers guidance on safe medication from the perspective of organism susceptibility and lays a foundation for research on the potential mechanisms of ARs.

The Pleiotropic Effects of Lipid-Modifying Interventions: Exploring Traditional and Emerging Hypolipidemic Therapies

Atherosclerotic cardiovascular disease poses a significant global health issue, with dyslipidemia standing out as a major risk factor. In recent decades, lipid-lowering therapies have evolved significantly, with statins emerging as the cornerstone treatment. These interventions play a crucial role in both primary and secondary prevention by effectively reducing cardiovascular risk through lipid profile enhancements. Beyond their primary lipid-lowering effects, extensive research indicates that these therapies exhibit pleiotropic actions, offering additional health benefits. These include anti-inflammatory properties, improvements in vascular health and glucose metabolism, and potential implications in cancer management. While statins and ezetimibe have been extensively studied, newer lipid-lowering agents also demonstrate similar pleiotropic effects, even in the absence of direct cardiovascular benefits. This narrative review explores the diverse pleiotropic properties of lipid-modifying therapies, emphasizing their non-lipid effects that contribute to reducing cardiovascular burden and exploring emerging benefits for non-cardiovascular conditions. Mechanistic insights into these actions are discussed alongside their potential therapeutic implications.

NAD+: An Old but Promising Therapeutic Agent for Skeletal Muscle Ageing

More than a century after the discovery of nicotinamide adenine dinucleotide (NAD+), our understanding of the molecule's role in the biology of ageing continues to evolve. As a coenzyme or substrate for many enzymes, NAD+ governs a wide range of biological processes, including energy metabolism, genomic stability, signal transduction, and cell fate. NAD+ deficiency has been recognised as a bona fide hallmark of tissue degeneration, and restoring NAD+ homeostasis helps to rejuvenate multiple mechanisms associated with tissue ageing. The progressive loss of skeletal muscle homeostasis with age is directly associated with high morbidity, disability and mortality. The aetiology of skeletal muscle ageing is complex, involving mitochondrial dysfunction, senescence and stem cell depletion, autophagy defects, chronic cellular stress, intracellular ion overload, immune cell dysfunction, circadian clock disruption, microcirculation disorders, persistent denervation, and gut microbiota dysbiosis. This review focuses on the therapeutic potential of NAD+ restoration to alleviate the above pathological factors and discusses the effects of in vivo administration of different NAD+ boosting strategies on skeletal muscle homeostasis, aiming to provide a reference for combating skeletal muscle ageing.

Exercise Prior to Lower Extremity Peripheral Artery Disease Improves Endurance Capacity and Hindlimb Blood Flow by Inhibiting Muscle Inflammation

Lower extremity peripheral artery disease (PAD) is associated with functional decline. Physical exercise has been proven to be an effective therapeutic strategy for PAD; however the effect of exercise initiated before PAD remains unknown. Here, we investigated the preventive effects of exercise on endurance capacity, hindlimb perfusion, and on polarization profile of circulating monocytes and limb muscle macrophages. ApoE^−/− mice were subjected to 5-week running wheel exercise or remained sedentary before induction of hindlimb ischemia. The two groups were thereafter kept sedentary. Exercised mice prior to PAD showed higher exhaustive treadmill running distance and time than sedentary mice. Preventive exercise also increased perfusion, arteriole density, and muscle regeneration in the ischemic hindlimb. Moreover, preventive exercise prevented ischemia-induced increased gene expression of pro-inflammatory M1 macrophages markers and cytokines in the ischemic muscle, while no changes were observed for anti-inflammatory M2 macrophage markers. Flow cytometry analysis showed that the proportion of circulating pro-inflammatory monocyte subtype decreased whereas that of anti-inflammatory monocytes increased with preventive exercise. Overall, we show that exercise initiated before PAD improves endurance performance and hindlimb perfusion in mice probably via inhibition of M1 macrophage polarization and inflammation in the ischemic muscle. Our study provides experimental evidence for a role of regular exercise in primary prevention of PAD.

Syncytialization and prolonged exposure to palmitate impacts BeWo respiration

Placental villous trophoblast mitochondrial respiratory function is critical for a successful pregnancy and environmental influences such as maternal obesity have been associated with respiratory impairment at term. More recently, a gestational high fat diet independent of maternal body composition, has been highlighted as a potential independent regulator of placental mitochondrial metabolism. The current study aimed to characterize the direct impact of a prolonged and isolated exposure to the dietary fatty acids Palmitate (PA) and Oleate (OA) upon placental cell mitochondrial respiratory function. BeWo cytotrophoblast (CT) and syncytiotrophoblast (SCT) cells were treated for 72 h with 100 µM PA, OA or PA+OA (P/O). Live-cell metabolic function was analyzed via the Seahorse XF Mito and Glycolysis Stress tests. Immunoblots and spectrophotometric activity assays were utilized to examine the protein expression and function of electron transport chain (ETC) complexes and key mitochondrial regulatory enzymes. Syncytialization of BeWo cells resulted reduced respiratory activity in conjunction with altered complex I and II activity and decreased pyruvate dehydrogenase (PDH) protein expression and activity. PA and P/O treatments were associated with increased basal and maximal respiratory activities in BeWo CT cells without alterations in protein expression or activity of individual ETC complexes and mitochondrial substrate regulators. The metabolic suppression in BeWo SCTs was consistent with that previously observed in primary human trophoblast cell cultures, while the observed increases in respiratory activity in PA-treated BeWo CTs may be indicative of an early timepoint of specific dietary saturated fat-mediated placental cell mitochondrial dysfunction.

Insight on Ameliorative Role of Selenium Nanoparticles and Niacin in Wound Healing on Adult Female Albino Mice

Background:

Wound healing is a complex process necessary for repairing damaged tissues and preventing infection. Selenium nanoparticles (Se NPs) were known due to their antioxidant and antimicrobial effects, also niacin has angiogenesis and antioxidant effects that are important in wound healing.

Objective:

The present study was conducted to investigate the effect of Se NPs and niacin in reducing and accelerating the wound healing time in mice.

Methods:

A simple wet chemical method has been modified to synthesize Se NPs in order to investigate their effect and niacin on reducing the wound healing in 80 adult female albino mice (250 mm2 full thickness open excision wound) that were divided into eight groups (10 mice/each). After 30-days, the mice were sacrificed, blood and tissue samples were taken for analysis.

Results:

The results showed that the percentage of wound area had been significantly reduced in Se NPs and niacin treated groups compared to the positive control. The level of Vascular Endothelial cell Growth Factor and Collagenase I in Se NPs and niacin groups significantly exceed those of other groups while Nitric Oxide (NO) was significantly decreased in treated groups. Liver and kidney functions showed the lower toxicity effect of Se NPs and niacin. Skin tissue showed the wound healing effect of Se NPs and niacin by regenerating skin layer compared to the positive group.

Conclusion:

Se NPs and niacin play an important role in accelerating and reducing the time of wound healing while they were antagonistic to each other.

Mitochondrial transplantation ameliorates acute limb ischemia

OBJECTIVE

Acute limb ischemia (ALI), the most challenging form of ischemia-reperfusion injury (IRI) in skeletal muscle tissue, leads to decreased skeletal muscle viability and limb function. Mitochondrial injury has been shown to play a key role in skeletal muscle IRI. In previous studies, we have demonstrated that mitochondrial transplantation (MT) is an efficacious therapeutic strategy to replace or to augment mitochondria damaged by IRI, allowing enhanced muscle viability and function in cardiac tissue. In this study, we investigated the efficacy of MT in a murine ALI model.

METHODS

C57BL/6J mice (male, 10-12 weeks) were used in a model of ALI. Ischemia was induced by applying a tourniquet on the left hindlimb. After 2 hours of ischemia, the tourniquet was released, and reperfusion of the hindlimb was re-established; either vehicle alone (n = 15) or vehicle containing mitochondria (n = 33) was injected directly into all the muscles of the hindlimb. Mitochondria were delivered at concentrations of 1 × 10⁶ to 1 × 10⁹ per gram wet weight to each muscle, and the animals were allowed to recover. Sham mice received no ischemia or injections but were anesthetized for 2 hours and allowed to recover. After 24 hours of recovery, limb function was assessed by DigiGait (Mouse Specifics Inc, Boston, Mass), and animals were euthanized; the gastrocnemius, soleus, and vastus medialis muscles were collected for analysis.

RESULTS

After 24 hours of hindlimb reperfusion, infarct size (percentage of total mass) and apoptosis were significantly decreased (P < .001, each) in the gastrocnemius, soleus, and vastus medialis muscles in MT mice compared with vehicle mice for all mitochondrial concentrations (1 × 10⁶ to 1 × 10⁹ per gram wet weight). DigiGait analysis at 24 hours of reperfusion showed that percentage shared stance time was significantly increased (P < .001) and stance factor was significantly decreased (P = .001) in vehicle compared with MT and sham mice. No significant differences in percentage shared stance time (P = .160) or stance factor (P = .545) were observed between MT and sham mice.

CONCLUSIONS

MT ameliorates skeletal muscle injury and enhances hindlimb function in the murine model of ALI.

Vitamin D intervention does not improve vascular regeneration in diet-induced obese male mice with peripheral ischemia

Vitamin D appears to either promote or inhibit neovascularization in a disease context-dependent manner. The effects of vitamin D, alone or in combination with niacin, on endothelial cell (EC) angiogenic function and on revascularization in obese animals with peripheral ischemia are unknown. Here, we report that supplementation of high palmitate medium with vitamin D, niacin or both vitamins increased EC tube formation, which relies primarily on cell migration, and also maintained tube stability over time. Transcriptomic analyses revealed that both vitamins increased stress response and anti-inflammatory gene expression. However, vitamin D decreased cell cycle gene expression and inhibited proliferation, while niacin induced stable expression of miR-126-3p and -5p and maintained cell proliferation in high palmitate. To assess vascular regeneration, diet-induced obese mice received vitamin D, niacin or both vitamins following hind limb ischemic injury. Niacin, but not vitamin D or combined treatment, improved recovery of hind limb use. Histology of tibialis anterior sections revealed no improvements in revascularization, regeneration, inflammation or fibrosis with vitamin D or combined treatment. In summary, although both vitamin D and niacin increased angiogenic function of EC cultures in high fat, only niacin improved recovery of hind limb use following ischemic injury in obese mice. It is possible that inhibition of cell proliferation by vitamin D in high-fat conditions limits vascular regeneration and recovery from peripheral ischemia in obesity.

Niacin promotes revascularization and recovery of limb function in diet-induced obese mice with peripheral ischemia

Niacin can reduce vascular disease risk in individuals with metabolic syndrome, but in light of recent large randomized controlled trials outcomes, its biological actions and clinical utility remain controversial. Niacin can improve endothelial function, vascular inflammation, and vascular regeneration, independent of correcting dyslipidemia, in various lean rodent models of vascular injury. Here, we tested whether niacin could directly improve endothelial cell angiogenic function during combined exposure to excess fatty acids and hypoxia, and whether intervention with niacin during continued feeding of western diet could improve revascularization and functional recovery in obese, hyperlipidemic mice with peripheral ischemia. Treatment with niacin (10 μmol/L) increased human microvascular endothelial cell angiogenic function during exposure to high fatty acids and hypoxia (2% oxygen), as determined by tube formation on Matrigel. To assess revascularization in vivo, we used western diet-induced obese mice with unilateral hind limb femoral artery ligation and excision. Treatment for 14 days postinjury with once daily i.p. injections of a low dose of niacin (50 mg/kg) improved recovery of hind limb use, in association with enhanced revascularization and decreased inflammation of the tibialis anterior muscle. These effects were concomitant with decreased plasma triglycerides, but not increased plasma apoAI. Thus, niacin improves endothelial tube formation under lipotoxic and hypoxic conditions, and moreover, promotes revascularization and functional hind limb recovery following ischemic injury in diet-induced obese mice with hyperlipidemia. These data may have implications for niacin therapy in the treatment of peripheral ischemic vascular disease associated with metabolic syndrome.