Peripheral Immunosenescence and Central Neuroinflammation: A Dangerous Liaison - A Dietary Approach

Chronic Stress as a Risk Factor for Type 2 Diabetes: Endocrine, Metabolic, and Immune Implications

BACKGROUND

Chronic stress is a condition of pressure on the brain and whole body, which in the long term may lead to a frank disease status, even including type 2 diabetes (T2D). Stress activates the hypothalamus-pituitary-adrenal axis with release of glucocorticoids (GCs) and catecholamines, as well as activation of the inflammatory pathway of the immune system, which alters glucose and lipid metabolism, ultimately leading to beta-cell destruction, insulin resistance and T2D onset. Alteration of the glucose and lipid metabolism accounts for insulin resistance and T2D outcome. Furthermore, stress-related subversion of the intestinal microbiota leads to an imbalance of the gut-brain-immune axis, as evidenced by the stress-related depression often associated with T2D. A condition of generalized inflammation and subversion of the intestinal microbiota represents another facet of stress-induced disease. In fact, chronic stress acts on the gut-brain axis with multiorgan consequences, as evidenced by the association between depression and T2D. Oxidative stress with the production of reactive oxygen species and cytokine-mediated inflammation represents the main hallmarks of chronic stress. ROS production and pro-inflammatory cytokines represent the main hallmarks of stress-related disorders, and therefore, the use of natural antioxidant and anti-inflammatory substances (nutraceuticals) may offer an alternative therapeutic approach to combat stress-related T2D. Single or combined administration of nutraceuticals would be very beneficial in targeting the neuro-endocrine-immune axis, thus, regulating major pathways involved in T2D onset. However, more clinical trials are needed to establish the effectiveness of nutraceutical treatment, dosage, time of administration and the most favorable combinations of compounds. Therefore, in view of their antioxidant and anti-inflammatory properties, the use of natural products or nutraceuticals for the treatment of stress-related diseases, even including T2D, will be discussed. Several evidences suggest that chronic stress represents one of the main factors responsible for the outcome of T2D.

Healthy lifestyles and wellbeing reduce neuroinflammation and prevent neurodegenerative and psychiatric disorders

Since the mid-20th century, Western societies have considered productivity and economic outcomes are more important than focusing on people's health and wellbeing. This focus has created lifestyles with high stress levels, associated with overconsumption of unhealthy foods and little exercise, which negatively affect people's lives, and subsequently lead to the development of pathologies, including neurodegenerative and psychiatric disorders. Prioritizing a healthy lifestyle to maintain wellbeing may slow the onset or reduce the severity of pathologies. It is a win-win for everyone; for societies and for individuals. A balanced lifestyle is increasingly being adopted globally, with many doctors encouraging meditation and prescribing non-pharmaceutical interventions to treat depression. In psychiatric and neurodegenerative disorders, the inflammatory response system of the brain (neuroinflammation) is activated. Many risks factors are now known to be linked to neuroinflammation such as stress, pollution, and a high saturated and trans fat diet. On the other hand, many studies have linked healthy habits and anti-inflammatory products with lower levels of neuroinflammation and a reduced risk of neurodegenerative and psychiatric disorders. Sharing risk and protective factors is critical so that individuals can make informed choices that promote positive aging throughout their lifespan. Most strategies to manage neurodegenerative diseases are palliative because neurodegeneration has been progressing silently for decades before symptoms appear. Here, we focus on preventing neurodegenerative diseases by adopting an integrated "healthy" lifestyle approach. This review summarizes the role of neuroinflammation on risk and protective factors of neurodegenerative and psychiatric disorders.

Therapeutic approaches of nutraceuticals in the prevention of Alzheimer's disease

Alzheimer's disease (AD) is a neurological illness that causes memory loss over time. Currently, available pharmaceutical medicines and products are limited, and they have side effects at a higher price. Researchers and scientists have observed significant effects of nutraceuticals. Various preclinical and clinical studies were investigated for the Anti-Alzheimer's activity of nutraceuticals. The increasing ability of the pathogenesis of AD has led to the analysis of novel therapeutic targets, including the pathophysiological mechanisms and distinct cascades. So, current improvement will show the most adequate and prominent nutraceuticals and suggested concise mechanisms involving autophagy regulation, anti-inflammatory, antioxidant, mitochondrial homeostasis, and others. The effects of nutraceuticals cannot be ignored; it is important to investigate high-quality clinical trials. Given the potential of nutraceuticals to battle AD as multi-targeted therapies, it's vital to evaluate them as viable lead compounds for drug discovery and development. To the best of the authors 'knowledge, modification of blood-brain barrier permeability, bioavailability, and aspects of randomized clinical trials should be considered in prospective investigations. PRACTICAL APPLICATIONS: Advancements in molecular diagnostic and fundamentals have implemented particular usefulness for drug evaluation. An excess of experimental knowledge occurs regarding the effect of nutraceuticals on AD. There are various preclinical and clinical studies that have been done on nutraceuticals. In addition, various substitute inhibit and enhance some pathophysiological levels associated with AD. Nutraceuticals are easily available and have fewer side effects with cost-effective advantages. However, further investigations and clinical trials are required to encourage its effect on disease.

Acute and chronic neuropsychiatric symptoms in novel coronavirus disease 2019 (COVID-19) patients: A qualitative review

The coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was declared a global pandemic by the World Health Organization (WHO) on March 11th, 2020. It has had unprecedented adverse effects on healthcare systems, economies, and societies globally. SARS-CoV-2 is not only a threat to physical health but has also been shown to have a severe impact on neuropsychiatric health. Many studies and case reports across countries have demonstrated insomnia, depressed mood, anxiety, post-traumatic stress disorder (PTSD), and cognitive change in COVID-19 patients during the acute phase of the infection, as well as in apparently recovered COVID-19 patients. The goal of this narrative review is to synthesize and summarize the emerging literature detailing the neuropsychiatric manifestations of COVID-19 with special emphasis on the long-term implications of COVID-19.

COVID-19 causes neuronal degeneration and reduces neurogenesis in human hippocampus

Recent investigations of COVID-19 have largely focused on the effects of this novel virus on the vital organs in order to efficiently assist individuals who have recovered from the disease. In the present study we used hippocampal tissue samples extracted from people who died after COVID-19. Utilizing histological techniques to analyze glial and neuronal cells we illuminated a massive degeneration of neuronal cells and changes in glial cells morphology in hippocampal samples. The results showed that in hippocampus of the studied brains there were morphological changes in pyramidal cells, an increase in apoptosis, a drop in neurogenesis, and change in spatial distribution of neurons in the pyramidal and granular layer. It was also demonstrated that COVID-19 alter the morphological characteristics and distribution of astrocyte and microglia cells. While the exact mechanism(s) by which the virus causes neuronal loss and morphology in the central nervous system (CNS) remains to be determined, it is necessary to monitor the effect of SARS-CoV-2 infection on CNS compartments like the hippocampus in future investigations. As a result of what happened in the hippocampus secondary to COVID-19, memory impairment may be a long-term neurological complication which can be a predisposing factor for neurodegenerative disorders through neuroinflammation and oxidative stress mechanisms.

Reducing neuroinflammation via therapeutic compounds and lifestyle to prevent or delay progression of Parkinson's disease

Parkinson's disease (PD) is the second most common age-associated neurodegenerative disorder and is characterised by progressive loss of dopamine neurons in the substantia nigra. Peripheral immune cell infiltration and activation of microglia and astrocytes are observed in PD, a process called neuroinflammation. Neuroinflammation is a fundamental response to protect the brain but, when chronic, it triggers neuronal damage. In the last decade, central and peripheral inflammation were suggested to occur at the prodromal stage of PD, sustained throughout disease progression, and may play a significant role in the pathology. Understanding the pathological mechanisms of PD has been a high priority in research, primarily to find effective treatments once symptoms are present. Evidence indicates that early life exposure to neuroinflammation as a consequence of life events, environmental or behaviour factors such as exposure to infections, pollution or a high fat diet increase the risk of developing PD. Many studies show healthy habits and products that decrease neuroinflammation also reduce the risk of PD. Here, we aim to stimulate discussion about the role of neuroinflammation in PD onset and progression. We highlight that reducing neuroinflammation throughout the lifespan is critical for preventing idiopathic PD, and present epidemiological studies that detail risk and protective factors. It is possible that introducing lifestyle changes that reduce neuroinflammation at the time of PD diagnosis may slow symptom progression. Finally, we discuss compounds and therapeutics to treat the neuroinflammation associated with PD.

Nutraceuticals-based therapeutic approach: recent advances to combat pathogenesis of Alzheimer's disease

Introduction: Alzheimer's disease (AD) is a progressive neurodegenerative disease accompanying memory deficits. The available pharmaceutical care has some limitations mostly entailing side effects, shelf-life, and patient's compliance. The momentous implications of nutraceuticals in AD have attracted scientists. Several preclinical studies for the investigation of nutraceuticals have been conducted.Areas covered: This review focuses on the potential use of a nutraceuticals-based therapeutic approach to treat and prevent AD. Increasing knowledge of AD pathogenesis has led to the discovery of new therapeutic targets including pathophysiological mechanisms and various cascades. Hence, the present contribution will attend to the most popular and effective nutraceuticals with proposed brief mechanisms entailing antioxidant, anti-inflammatory, autophagy regulation, mitochondrial homeostasis, and more. Therefore, even though the effectiveness of nutraceuticals cannot be dismissed, it is essential to do further high-quality randomized clinical trials.Expert opinion: According to the potential of nutraceuticals to combat AD as multi-target directed drugs, there is critical importance to assess them as feasible lead compounds for drug discovery and development. To the best of the authors' knowledge, modification of blood-brain barrier permeability, bioavailability, and features of randomized clinical trials should be considered in prospective studies.

COVID-19, Mast Cells, Cytokine Storm, Psychological Stress, and Neuroinflammation

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new pandemic infectious disease that originated in China. COVID-19 is a global public health emergency of international concern. COVID-19 causes mild to severe illness with high morbidity and mortality, especially in preexisting risk groups. Therapeutic options are now limited to COVID-19. The hallmark of COVID-19 pathogenesis is the cytokine storm with elevated levels of interleukin-6 (IL-6), IL-1β, tumor necrosis factor-alpha (TNF-α), chemokine (C-C-motif) ligand 2 (CCL2), and granulocyte-macrophage colony-stimulating factor (GM-CSF). COVID-19 can cause severe pneumonia, and neurological disorders, including stroke, the damage to the neurovascular unit, blood-brain barrier disruption, high intracranial proinflammatory cytokines, and endothelial cell damage in the brain. Mast cells are innate immune cells and also implicated in adaptive immune response, systemic inflammatory diseases, neuroinflammatory diseases, traumatic brain injury and stroke, and stress disorders. SARS-CoV-2 can activate monocytes/macrophages, dendritic cells, T cells, mast cells, neutrophils, and induce cytokine storm in the lung. COVID-19 can activate mast cells, neurons, glial cells, and endothelial cells. SARS-CoV-2 infection can cause psychological stress and neuroinflammation. In conclusion, COVID-19 can induce mast cell activation, psychological stress, cytokine storm, and neuroinflammation.

Worse progression of COVID-19 in men: Is testosterone a key factor?

Background

The novel severe acute respiratory syndrome coronavirus (SARS‐CoV‐2) disease 2019 (COVID‐19) seems to have a worse clinical course among infected men compared with women, thus highlighting concerns about gender predisposition to serious prognosis. Therefore, androgens, particularly testosterone (T), could be suspected as playing a critical role in driving this excess of risk. However, gonadal function in critically ill men is actually unknown, mainly because serum T concentration is not routinely measured in clinical practice, even more in this clinical context.

Objective

To overview on possible mechanisms by which serum T levels could affect the progression of COVID‐19 in men.

Methods

Authors searched PubMed/MEDLINE, Web of Science, EMBASE, Cochrane Library, Google, and institutional websites for medical subject headings terms and free text words referred to “SARS‐CoV‐2,” “COVID‐19,” “testosterone,” “male hypogonadism,” “gender” “immune system,” “obesity,” “thrombosis” until May 19th 2020.

Results

T, co‐regulating the expression of angiotensin‐converting enzyme 2 and transmembrane protease serine 2 in host cells, may facilitate SARS‐CoV‐2 internalization. Instead, low serum T levels may predispose to endothelial dysfunction, thrombosis and defective immune response, leading to both impaired viral clearance and systemic inflammation. Obesity, one of the leading causes of severe prognosis in infected patients, is strictly associated with functional hypogonadism, and may consistently strengthen the aforementioned alterations, ultimately predisposing to serious respiratory and systemic consequences.

Discussion and conclusion

T in comparison to estrogen may predispose men to a widespread COVID‐19 infection. Low serum levels of T, which should be supposed to characterize the hormonal milieu in seriously ill individuals, may predispose men, especially elderly men, to poor prognosis or death. Further studies are needed to confirm these pathophysiological assumptions and to promptly identify adequate therapeutic strategies.

Oral Microbiota and Immune System Crosstalk: A Translational Research

BACKGROUND

Oral pathogens may exert the ability to trigger differently the activation of local macrophage immune responses, for instance Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans induce predominantly pro-inflammatory (M1-like phenotypes) responses, while oral commensal microbiota primarily elicits macrophage functions consistent with the anti-inflammatory (M2-like phenotypes).

METHODS

In healthy individuals vs. periodontal disease patients' blood samples, the differentiation process from monocyte to M1 and M2 was conducted using two typical growth factors, the granulocyte/macrophage colony stimulating factor (GM-CSF) and the macrophage colony stimulating factor (M-CSF).

RESULTS

In contrast with the current literature our outcomes showed a noticeable increase of macrophage polarization from healthy individuals vs. periodontal patients. The biological and clinical significance of these data was discussed.

CONCLUSIONS

Our translational findings showed a significant variance between control versus periodontal disease groups in M1 and M2 marker expression within the second group significantly lower skews differentiation of M2-like macrophages towards an M1-like phenotype. Macrophage polarization in periodontal tissue may be responsible for the development and progression of inflammation-induced periodontal tissue damage, including alveolar bone loss, and modulating macrophage function may be a potential strategy for periodontal disease management.