Nicotinamide mononucleotides alleviated neurological impairment via anti-neuroinflammation in traumatic brain injury

Impact of increasing one-carbon metabolites on traumatic brain injury outcome using pre-clinical models

Traumatic brain injury is a major cause of death and disability worldwide, affecting over 69 million individuals yearly. One-carbon metabolism has been shown to have beneficial effects after brain damage, such as ischemic stroke. However, whether increasing one-carbon metabolite vitamins impacts traumatic brain injury outcomes in patients requires more investigation. The aim of this review is to evaluate how one-carbon metabolites impact outcomes after the onset of traumatic brain injury. PubMed, Web of Science, and Google Scholar databases were searched for studies that examined the impact of B-vitamin supplementation on traumatic brain injury outcomes. The search terms included combinations of the following words: traumatic brain injury, dietary supplementation, one-carbon metabolism, and B-vitamins. The focus of each literature search was basic science data. The year of publication in the literature searches was not limited. Our analysis of the literature has shown that dietary supplementation of B-vitamins has significantly improved the functional and behavioral recovery of animals with traumatic brain injury compared to controls. However, this improvement is dosage-dependent and is contingent upon the onset of supplementation and whether there is a sustained or continuous delivery of vitamin supplementation post-traumatic brain injury. The details of supplementation post-traumatic brain injury need to be further investigated. Overall, we conclude that B-vitamin supplementation improves behavioral outcomes and reduces cognitive impairment post-traumatic brain injury in animal model systems. Further investigation in a clinical setting should be strongly considered in conjunction with current medical treatments for traumatic brain injury-affected individuals.

Fucoxanthin ameliorates traumatic brain injury by suppressing the blood-brain barrier disruption

Fucoxanthin is the most abundant marine carotenoid extracted from seaweed. Our previous study has shown that fucoxanthin inhibited oxidative stress after traumatic brain injury (TBI). However, the effects of fucoxanthin on TBI-induced blood-brain barrier (BBB) destruction have not been well understood. In the present study, we found that fucoxanthin improved neurological dysfunction, reduced brain edema, attenuated cortical lesion volume, and decreased dendrites loss after TBI in vivo. Moreover, fucoxanthin suppressed BBB leakage, preserved tight junction (TJ) and adherens junction (AJ) proteins, and inhibited MMP-9 expression. Furthermore, fucoxanthin alleviated apoptosis and ferroptosis, and activated mitophagy in endothelial cells (ECs) after TBI. However, the protection of fucoxanthin on BBB was attenuated when mitophagy was inhibited. Importantly, fucoxanthin also provided protective effects in bEnd.3 cells after TBI. Taken together, our results suggested that fucoxanthin played a key role in the protection of BBB after TBI through mitophagy.

Bone Allograft Acid Lysates Change the Genetic Signature of Gingival Fibroblasts

Bone allografts are widely used as osteoconductive support to guide bone regrowth. Bone allografts are more than a scaffold for the immigrating cells as they maintain some bioactivity of the original bone matrix. Yet, it remains unclear how immigrating cells respond to bone allografts. To this end, we have evaluated the response of mesenchymal cells exposed to acid lysates of bone allografts (ALBA). RNAseq revealed that ALBA has a strong impact on the genetic signature of gingival fibroblasts, indicated by the increased expression of IL11, AREG, C11orf96, STC1, and GK-as confirmed by RT-PCR, and for IL11 and STC1 by immunoassays. Considering that transforming growth factor-β (TGF-β) is stored in the bone matrix and may have caused the expression changes, we performed a proteomics analysis, TGF-β immunoassay, and smad2/3 nuclear translocation. ALBA neither showed detectable TGF-β nor was the lysate able to induce smad2/3 translocation. Nevertheless, the TGF-β receptor type I kinase inhibitor SB431542 significantly decreased the expression of IL11, AREG, and C11orf96, suggesting that other agonists than TGF-β are responsible for the robust cell response. The findings suggest that IL11, AREG, and C11orf96 expression in mesenchymal cells can serve as a bioassay reflecting the bioactivity of the bone allografts.

The Combination of Citicoline and Nicotinamide Mononucleotide Induces Neurite Outgrowth and Mitigates Vascular Cognitive Impairment via SIRT1/CREB Pathway

Vascular dementia (VD) is characterized with vascular cognitive impairment (VCI), which currently has few effective therapies in clinic. Neuronal damage and white matter injury are involved in the pathogenesis of VCI. Citicoline has been demonstrated to exhibit neuroprotection and neurorepair to improve cognition in cerebrovascular diseases. Nicotinamide adenine dinucleotide (NAD+)-dependent sirtuin (SIRT) signaling pathway constitutes a strong intrinsic defense system against various stresses including neuroinflammation in VCI. Our hypothesis is that the combined use of citicoline and the precursor of NAD+, nicotinamide mononucleotide (NMN), could enhance action on cognitive function in VCI. We investigated the synergistic effect of these two drugs in the rat model of VCI by bilateral common carotid artery occlusion (BCCAO). Citicoline significantly enhanced neurite outgrowth in Neuro-2a cells, and the combination of citicoline and NMN remarkably induced neurite outgrowth in Neuro-2a cells and primary cortical neuronal cells with an optimal proportion of 4:1. In the rat model of BCCAO, when two drugs in combination of 160 mg/kg citicoline and 40 mg/kg NMN, this combination administrated at 7 days post-BCCAO significantly improved the cognitive impairment in BCCAO rats compared with vehicle group by the analysis of the Morris water maze and the novel object recognition test. This combination also decreased microglial activation and neuroinflammation, and protected white matter integrity indicated by the increased myelin basic protein (MBP) expression through activation of SIRT1/TORC1/CREB signaling pathway. Our results suggest that the combination of citicoline and NMN has a synergistic effect for the treatment of VD associated with VCI.

Nicotinamide Deteriorates Post-Stroke Immunodepression Following Cerebral Ischemia-Reperfusion Injury in Mice

(1) Background: Inducing experimental stroke leads to biphasic immune responses, where the early activation of immune functions is followed by severe immunosuppression accompanied by spleen and thymus atrophy. Nicotinamide, a water-soluble B-group vitamin, is a known neuroprotectant against brain ischemia in animal models. We examined the effect of nicotinamide on the central and peripheral immune response in experimental stroke models. (2) Methods: Nicotinamide (500 mg/kg) or saline was intravenously administered to C57BL/6 mice during reperfusion after transiently occluding the middle cerebral artery or after LPS injection. On day 3, the animals were examined for behavioral performance and were then sacrificed to assess brain infarction, blood-brain barrier (BBB) integrity, and the composition of immune cells in the brain, thymus, spleen, and blood using flow cytometry. (3) Results: Nicotinamide reduced brain infarction and microglia/macrophage activation following MCAo (p < 0.05). Similarly, in LPS-injected mice, microglia/macrophage activation was decreased upon treatment with nicotinamide (p < 0.05), suggesting a direct inhibitory effect of nicotinamide on microglia/macrophage activation. Nicotinamide decreased the infiltration of neutrophils into the brain parenchyma and ameliorated Evans blue leakage (p < 0.05), suggesting that a decreased infiltration of neutrophils could, at least partially, be the result of a more integrated BBB structure following nicotinamide treatment. Our studies also revealed that administering nicotinamide led to retarded B-cell maturation in the spleen and subsequently decreased circulating B cells in the thymus and bloodstream (p < 0.05). (4) Conclusions: Cumulatively, nicotinamide decreased brain inflammation caused by ischemia-reperfusion injury, which was mediated by a direct anti-inflammatory effect of nicotinamide and an indirect protective effect on BBB integrity. Administering nicotinamide following brain ischemia resulted in a decrease in circulating B cells. This warrants attention with respect to future clinical applications.