Intestinal microbiota and melatonin in the treatment of secondary injury and complications after spinal cord injury

Effect of bacteriocin RSQ01 on milk microbiota during pasteurized milk preservation

Milk has high risk for microbial contamination. RSQ01, a bacteriocin, previously has shown potentiality for pasteurized milk preservation. This study analyzed the effects of RSQ01 on milk microbiota by comparison of bacterial number and composition in 3 pasteurized milk groups: controls without RSQ01, treatment group with the addition of 2× MIC (low concentration), and treatment group with the addition of 4× MIC RSQ01 (high concentration). Integrated 16S ribosomal DNA sequencing and metagenomics of these groups after 3 d of storage showed inhibition of RSQ01 on microbiota diversity. Pathogenic bacteria such as Salmonella showed a decrease in relative abundance after RSQ01 treatment, whereas probiotic bacteria such as Lactococcus showed an increase, indicating that RSQ01 contributed to milk preservation by maintaining a low abundance of pathogens and a relatively high abundance of probiotics. Further investigations revealed that milk preservation was primarily attributed to the ability of RSQ01 to decrease the relative abundance of genes related to metabolism of energy and nutrients (e.g., vitamins, lipids, and AA) of microbiota, with change of genetic, environmental, and cellular processes. Interestingly, RSQ01 generally reduced the relative abundance of virulence factors and quorum-sensing-related genes in microbiota, likely reducing virulence and resistance. The findings provided insights into microbiomics mechanisms regarding pasteurized milk preservation of bacteriocins.

Tanshinone IIA Promotes Functional Recovery After Spinal Cord Injury by Inhibiting Neuron and Oligodendrocyte Ferroptosis Through the GPX4/ACSL4 Axis

Spinal cord injury (SCI) induces severe functional impairments and involves intricate secondary injury mechanisms. Tanshinone IIA (TIIA), a key bioactive component of Salvia miltiorrhiza, exhibits neuroprotective potential, yet its role in ferroptosis regulation post-SCI remains undefined. This study explored the protective effects and underlying mechanisms of TIIA in SCI. In a rat SCI model, TIIA markedly enhanced hind limb motor function and preserved histopathological integrity while mitigating mitochondrial damage, ferroptosis, and oxidative stress. TIIA attenuated ferroptosis by reducing reactive oxygen species (ROS), malondialdehyde (MDA), and acyl-CoA synthetase long-chain family member 4 (ACSL4) while elevating glutathione (GSH), superoxide dismutase (SOD), and glutathione peroxidase 4 (GPX4) levels. Mechanistically, TIIA suppressed ferroptosis through modulation of the GPX4/ACSL4 axis. The ferroptosis inducer RSL3 abrogated these protective effects, further validating this mechanism. These findings highlight the therapeutic potential of TIIA in SCI by targeting the GPX4/ACSL4 pathway to attenuate ferroptosis and promote functional recovery.

Melatonin supplementation: new insights into health and disease

BACKGROUND

Melatonin supplementation has gained considerable attention for its potential health impacts. This study aimed to review the recent literature on melatonin supplementation and its implications in areas such as obesity, diabetes, gut microbiome, neurodegenerative diseases, cancer, sports performance, sleep quality, psychiatric disorders, pediatrics, pregnancy, and respiratory health. Additionally, assess the supplementation protocols, potential adverse effects, associated risks, and symptoms observed during supplementation.

METHODS

An extensive search was conducted across multiple databases, including PubMed, Scielo, Web of Science, CrossRef, and Google Scholar, focusing on publications from 2011 to 2024. A total of 71 articles were collected and analyzed.

RESULTS

Recent studies highlight melatonin's promising antioxidant, anti-inflammatory, and immunomodulatory properties, particularly in improving sleep quality and addressing specific neurodegenerative diseases. Evidence supports its role in reducing anxiety in preoperative contexts and enhancing recovery under certain conditions in athletes. However, findings on melatonin's role in obesity, glycemic control, and gut microbiome regulation remain inconsistent and influenced by external factors such as diet and exercise. Similarly, evidence supporting its efficacy in cancer, psychiatric disorders, pregnancy, and pediatrics is limited and requires further research. For respiratory health, while melatonin's theoretical benefits include reducing oxidative stress and inflammation, current evidence is weak and largely preclinical. Concerns regarding adverse effects, including nightmares and grogginess, highlight the importance of thorough and careful monitoring. To ensure safety and effectiveness, supplementation protocols should be tailored to meet the unique needs of each individual.

CONCLUSION

Melatonin supplementation is not a universal solution but a potentially valuable tool in specific contexts. Its benefits are most evident in sleep regulation and certain neurodegenerative conditions. However, significant gaps in research, including inconsistent methodologies, small sample sizes, and limited data on long-term effects, necessitate further robust clinical trials. Individualized recommendations and cautious interpretation of findings are essential, particularly given the variability in outcomes based on study designs and populations.

Mental Health Disorders Due to Gut Microbiome Alteration and NLRP3 Inflammasome Activation After Spinal Cord Injury: Molecular Mechanisms, Promising Treatments, and Aids from Artificial Intelligence

Aside from its immediate traumatic effects, spinal cord injury (SCI) presents multiple secondary complications that can be harmful to those who have been affected by SCI. Among these secondary effects, gut dysbiosis (GD) and the activation of the NOD (nucleotide-binding oligomerization domain) like receptor-family pyrin-domain-containing three (NLRP3) inflammasome are of special interest for their roles in impacting mental health. Studies have found that the state of the gut microbiome is thrown into disarray after SCI, providing a chance for GD to occur. Metabolites such as short-chain fatty acids (SCFAs) and a variety of neurotransmitters produced by the gut microbiome are hampered by GD. This disrupts healthy cognitive processes and opens the door for SCI patients to be impacted by mental health disorders. Additionally, some studies have found an increased presence and activation of the NLRP3 inflammasome and its respective parts in SCI patients. Preclinical and clinical studies have shown that NLRP3 inflammasome plays a key role in the maturation of pro-inflammatory cytokines that can initiate and eventually aggravate mental health disorders after SCI. In addition to the mechanisms of GD and the NLRP3 inflammasome in intensifying mental health disorders after SCI, this review article further focuses on three promising treatments: fecal microbiome transplants, phytochemicals, and melatonin. Studies have found these treatments to be effective in combating the pathogenic mechanisms of GD and NLRP3 inflammasome, as well as alleviating the symptoms these complications may have on mental health. Another area of focus of this review article is exploring how artificial intelligence (AI) can be used to support treatments. AI models have already been developed to track changes in the gut microbiome, simulate drug-gut interactions, and design novel anti-NLRP3 inflammasome peptides. While these are promising, further research into the applications of AI for the treatment of mental health disorders in SCI is needed.

Spinal cord injury: pathophysiology, possible treatments and the role of the gut microbiota

Spinal cord injury (SCI) is a devastating pathological state causing motor, sensory, and autonomic dysfunction. To date, SCI remains without viable treatment for its patients. After the injury, molecular events centered at the lesion epicenter create a non-permissive environment for cell survival and regeneration. This newly hostile setting is characterized by necrosis, inflammation, demyelination, axotomy, apoptosis, and gliosis, among other events that limit locomotor recovery. This review provides an overview of the pathophysiology of SCI, highlighting the potential role of the gut microbiota in modulating the inflammatory response and influencing neurological recovery following trauma to the spinal cord. Emphasis on the bidirectional communication between the gut and central nervous system, known as the gut-brain axis is given. After trauma, the gut-brain/spinal cord axis promotes the production of pro-inflammatory metabolites that provide a non-permissive environment for cell survival and locomotor recovery. Therefore, any possible pharmacological treatment, including antibiotics and painkillers, must consider their effects on microbiome dysbiosis to promote cell survival, regeneration, and behavioral improvement. Overall, this review provides valuable insights into the pathophysiology of SCI and the evolving understanding of the role of the gut microbiota in SCI, with implications for future research and clinical practice.

Melatonin Sources in Sheep Rumen and Its Role in Reproductive Physiology

In mammals, the melatonin (Mel) concentration in the gastrointestinal tract is 400 times greater than in the pineal gland. However, the origin of Mel in the gastrointestinal tract and its role in reproductive regulation remains unclear. Therefore, we analyzed three potential Mel sources (feed, microorganisms, and the rumen wall) for their contribution to high Mel levels in the rumen and their biological effects. The feed contained high Mel concentrations, and Mel in rumen fluid and blood peaked two hours after feeding. Rumen microbial analysis showed a strong positive correlation between Mel and specific microbes, including Megasphaera, Butyrivibrio, Acetobacter, and Olsenella. In vitro experiments indicated that rumen microorganisms synthesized Mel from tryptophan. The rumen wall also contains key enzymes, AANAT and HIOMT, which catalyze Mel synthesis and membrane receptors MT1 and MT2 that mediate the function of Mel, suggesting that the rumen wall synthesizes Mel. Mel peaked in both rumen fluid and blood two hours after feeding. Feeding also altered blood levels of Mel, Gonadotropin-releasing hormone (GnRH), Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), progesterone (P4), and Estradiol (E2), with a correlation between Mel and fluctuations in GnRH, LH, P4, and E2 levels. Our findings suggest that feed is the primary source of high Mel levels in the rumen and impacts reproductive hormone fluctuations. This study elucidates the origin of high rumen Mel concentrations and reveals that food intake affects the natural secretion of various hormones, offering a new perspective on food sources for regulating reproductive physiology.

Mechanisms of inflammation after ischemic stroke in brain-peripheral crosstalk

Stroke is a devastating disease with high morbidity, disability, and mortality, among which ischemic stroke is more common. However, there is still a lack of effective methods to improve the prognosis and reduce the incidence of its complications. At present, there is evidence that peripheral organs are involved in the inflammatory response after stroke. Moreover, the interaction between central and peripheral inflammation includes the activation of resident and peripheral immune cells, as well as the activation of inflammation-related signaling pathways, which all play an important role in the pathophysiology of stroke. In this review, we discuss the mechanisms of inflammatory response after ischemic stroke, as well as the interactions through circulatory pathways between peripheral organs (such as the gut, heart, lung and spleen) and the brain to mediate and regulate inflammation after ischemic stroke. We also propose the potential role of meningeal lymphatic vessels (MLVs)-cervical lymph nodes (CLNs) as a brain-peripheral crosstalk lymphatic pathway in ischemic stroke. In addition, we also summarize the mechanisms of anti-inflammatory drugs in the treatment of ischemic stroke.

Gut microbiota in neurological diseases: Melatonin plays an important regulatory role

Melatonin is a highly conserved molecule produced in the human pineal gland as a hormone. It is known for its essential biological effects, such as antioxidant activity, circadian rhythm regulator, and immunomodulatory effects. The gut is one of the primary known sources of melatonin. The gut microbiota helps produce melatonin from tryptophan, and melatonin has been shown to have a beneficial effect on gut barrier function and microbial population. Dysbiosis of the intestinal microbiota is associated with bacterial imbalance and decreased beneficial microbial metabolites, including melatonin. In this way, low melatonin levels may be related to several human diseases. Melatonin has shown both preventive and therapeutic effects against various conditions, including neurological diseases such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis. This review was aimed to discuss the role of melatonin in the body, and to describe the possible relationship between gut microbiota and melatonin production, as well as the potential therapeutic effects of melatonin on neurological diseases.

Mechanism of Action of Melatonin as a Potential Adjuvant Therapy in Inflammatory Bowel Disease and Colorectal Cancer

Inflammatory bowel disease (IBD), a continuum of chronic inflammatory diseases, is tightly associated with immune system dysregulation and dysbiosis, leading to inflammation in the gastrointestinal tract (GIT) and multiple extraintestinal manifestations. The pathogenesis of IBD is not completely elucidated. However, it is associated with an increased risk of colorectal cancer (CRC), which is one of the most common gastrointestinal malignancies. In both IBD and CRC, a complex interplay occurs between the immune system and gut microbiota (GM), leading to the alteration in GM composition. Melatonin, a neuroendocrine hormone, was found to be involved with this interplay, especially since it is present in high amounts in the gut, leading to some protective effects. Actually, melatonin enhances the integrity of the intestinal mucosal barrier, regulates the immune response, alleviates inflammation, and attenuates oxidative stress. Thereby, the authors summarize the multifactorial interaction of melatonin with IBD and with CRC, focusing on new findings related to the mechanisms of action of this hormone, in addition to its documented positive outcomes on the treatment of these two pathologies and possible future perspectives to use melatonin as an adjuvant therapy.

Gut microbiota changes in animal models of spinal cord injury: a preclinical systematic review and meta-analysis

BACKGROUND

An increasing number of studies show that the intestinal flora is closely related to spinal cord injury. Many researchers are exploring the changes in the richness, diversity, and evenness of intestinal flora in spinal cord injury animal models to identify the characteristic bacteria.

METHODS

A comprehensive literature search was conducted using three databases: PubMed, Embase, and Web of Science. A meta-analysis was performed using R 4.3.1 to evaluate the comparison of microbiota diversity, richness, and evenness and the relative abundance of intestinal microbiota in animals with spinal cord injury and blank controls.

RESULTS

Fifteen studies were included in the meta-analysis, of which 12 involved gut microbiota distribution indicators and 11 included intestinal microflora relative abundance indicators. Meta-analysis of high-dimensional indicators describing the distribution of the gut microbiota identified a substantial decline in the evenness and richness of the intestinal flora. In addition, the Actinobacteria phylum and Erysipelotrichales and Clostridiales orders were significantly different between the spinal cord injury and sham groups; therefore, they may be the characteristic bacteria in spinal cord injury models.

CONCLUSION

Our meta-analysis suggested that the gut microbiota in the spinal cord injury animal model group was altered compared with that in the control group, with varying degrees of changes in richness and evenness and potentially pathogenic characteristic flora. More rigorous methodological studies are needed because of the high heterogeneity and limited sample size. Further research is needed to clinically apply intestinal microbiota and potentially guide fecal microbiota transplantation therapy.

Melatonin, a natural antioxidant therapy in spinal cord injury

Spinal cord injury (SCI) is a sudden onset of disruption to the spinal neural tissue, leading to loss of motor control and sensory function of the body. Oxidative stress is considered a hallmark in SCI followed by a series of events, including inflammation and cellular apoptosis. Melatonin was originally discovered as a hormone produced by the pineal gland. The subcellular localization of melatonin has been identified in mitochondria, exhibiting specific onsite protection to excess mitochondrial reactive oxygen species and working as an antioxidant in diseases. The recent discovery regarding the molecular basis of ligand selectivity for melatonin receptors and the constant efforts on finding synthetic melatonin alternatives have drawn researchers' attention back to melatonin. This review outlines the application of melatonin in SCI, including 1) the relationship between the melatonin rhythm and SCI in clinic; 2) the neuroprotective role of melatonin in experimental traumatic and ischemia/reperfusion SCI, i.e., exhibiting anti-oxidative, anti-inflammatory, and anti-apoptosis effects, facilitating the integrity of the blood-spinal cord barrier, ameliorating edema, preventing neural death, reducing scar formation, and promoting axon regeneration and neuroplasticity; 3) protecting gut microbiota and peripheral organs; 4) synergizing with drugs, rehabilitation training, stem cell therapy, and biomedical material engineering; and 5) the potential side effects. This comprehensive review provides new insights on melatonin as a natural antioxidant therapy in facilitating rehabilitation in SCI.