Neuroimmune regulation of microglial activity involved in neuroinflammation and neurodegenerative diseases

Vanillic acid ameliorates diethyl phthalate and bisphenol S-induced oxidative stress and neuroinflammation in the hippocampus of experimental rats

Long-term adverse effects on human health are caused by exogenous compounds that alter the functions of biological systems, especially neuroendocrine disruptors like diethyl phthalate (DEP) and bisphenol S (BPS). Although vanillic acid (VA) has pertinent neuropharmacological characteristics, its effect against DEP + BPS-induced neurotoxicity has not been explored. This study proposed that VA may offer protection against the neurotoxicity caused by DEP + BPS. Thirty male Wistar rats were randomly distributed across five groups: a control group receiving DMSO, a group exposed to a mixture of BPS and DEP, two BPS + DEP-exposed groups treated with VA at doses of 25 mg/kg or 50 mg/kg, and a nonexposed group treated with 50 mg VA/kg. After 21 days, the hippocampal tissues were processed for biochemical analyses. Our results indicate that exposure to DEP + BPS upregulated neurosignaling mediators (NTPDase, ADA, MAO-A, and Ca2+), inhibited others (AChE and Ca2+/Mg2+-ATPase), decreased hippocampus antioxidants (GSH, GPx, CAT, and SOD), and elevated markers of oxidative stress/damage (NO, H2O2, MDA, and AOPP). AR, BAX, TNF-α, BAK1, and IL-1β expressions were upregulated, while IL-10 and BDNF expressions were downregulated. NF-κB and caspase-3/9 pathways were also upregulated. Co-treatment with vanillic acid remarkably precluded these neurotoxic outcomes by improving neurosignaling, augmenting antioxidant status, abrogating oxidative damage, inflammation (TNF-α, IL-1β), and apoptosis (BAX, BAK1, caspase-3/9). Vanillic acid also restored IL-10 and BDNF levels, thereby exhibiting neuroprotective effects, corroborated by histological examinations. We posit vanillic acid as a safe and effective therapeutic agent against neurotoxicity occasioned by exposure to neuroendocrine disruptors.

"Inflamed" depression: A review of the interactions between depression and inflammation and current anti-inflammatory strategies for depression

Depression is a common mental disorder, the effective treatment of which remains a challenging issue worldwide. The clinical pathogenesis of depression has been deeply explored, leading to the formulation of various pathogenic hypotheses. Among these, the monoamine neurotransmitter hypothesis holds a prominent position, yet it has significant limitations as more than one-third of patients do not respond to conventional treatments targeting monoamine transmission disturbances. Over the past few decades, a growing body of research has highlighted the link between inflammation and depression as a potential key factor in the pathophysiology of depression. In this review, we first summarize the relationship between inflammation and depression, with a focus on the pathophysiological changes mediated by inflammation in depression. The mechanisms linking inflammation to depression as well as multiple anti-inflammatory strategies are also discussed, and their efficacy and safety are assessed. This review broadens the perspective on specific aspects of using anti-inflammatory strategies for treating depression, laying the groundwork for advancing precision medicine for individuals suffering from "inflamed" depression.

HIV-associated neurocognitive disorder: key implications of the microbiota-gut-brain axis

HIV-associated neurocognitive disorder (HAND) is now recognized to be relatively common in people living with HIV (PLWH), and remains a common cause of cognitive impairment. Unfortunately, the fundamental pathogenic processes underlying this specific outcome of HIV infection have not as yet been fully elucidated. With increased interest in research related to the microbiota-gut-brain axis, the gut-brain axis has been shown to play critical roles in regulating central nervous system disorders such as Alzheimer's disease and Parkinson's disease. PLWH are characterized by a particular affliction, referred to as gut-associated dysbiosis syndrome, which provokes an alteration in microbial composition and diversity, and of their associated metabolite composition within the gut. Interestingly, the gut microbiota has also been recognized as a key element, which both positively and negatively influences human brain health, including the functioning and development of the central nervous system (CNS). In this review, based on published evidence, we critically discuss the relevant interactions between the microbiota-gut-brain axis and the pathogenesis of HAND in the context of HIV infection. It is likely that HAND manifestation in PLWH mainly results from (i) gut-associated dysbiosis syndrome and a leaky gut on the one hand and (ii) inflammation on the other hand. In other words, the preceding features of HIV infection negatively alter the composition of the gut microbiota (microbes and their associated metabolites) and promote proinflammatory immune responses which singularly or in tandem damage neurons and/or induce inadequate neuronal signaling. Thus, HAND is fairly prevalent in PLWH. This work aims to demonstrate that in the quest to prevent and possibly treat HAND, the gut microbiota may ultimately represent a therapeutically targetable "host factor."

Insulin resistance in the retina: possible implications for certain ocular diseases

Insulin resistance (IR) is becoming a worldwide medical and public health challenge as an increasing prevalence of obesity and metabolic disorders. Accumulated evidence has demonstrated a strong relationship between IR and a higher incidence of several dramatically vision-threatening retinal diseases, including diabetic retinopathy, age-related macular degeneration, and glaucoma. In this review, we provide a schematic overview of the associations between IR and certain ocular diseases and further explore the possible mechanisms. Although the exact causes explaining these associations have not been fully elucidated, underlying mechanisms of oxidative stress, chronic low-grade inflammation, endothelial dysfunction and vasoconstriction, and neurodegenerative impairments may be involved. Given that IR is a modifiable risk factor, it may be important to identify patients at a high IR level with prompt treatment, which may decrease the risk of developing certain ocular diseases. Additionally, improving IR through the activation of insulin signaling pathways could become a potential therapeutic target.

Microglial response to aging and neuroinflammation in the development of neurodegenerative diseases

ABSTRACT

Cellular senescence and chronic inflammation in response to aging are considered to be indicators of brain aging; they have a great impact on the aging process and are the main risk factors for neurodegeneration. Reviewing the microglial response to aging and neuroinflammation in neurodegenerative diseases will help understand the importance of microglia in neurodegenerative diseases. This review describes the origin and function of microglia and focuses on the role of different states of the microglial response to aging and chronic inflammation on the occurrence and development of neurodegenerative diseases, including Alzheimer's disease, Huntington's chorea, and Parkinson's disease. This review also describes the potential benefits of treating neurodegenerative diseases by modulating changes in microglial states. Therefore, inducing a shift from the neurotoxic to neuroprotective microglial state in neurodegenerative diseases induced by aging and chronic inflammation holds promise for the treatment of neurodegenerative diseases in the future.

Normal-Tension Glaucoma and Potential Clinical Links to Alzheimer's Disease

Glaucoma is a group of optic neuropathies and the world's leading cause of irreversible blindness. Normal-tension glaucoma (NTG) is a subtype of glaucoma that is characterized by a typical pattern of peripheral retinal loss, in which the patient's intraocular pressure (IOP) is considered within the normal range (<21 mmHg). Currently, the only targetable risk factor for glaucoma is lowering IOP, and patients with NTG continue to experience visual field loss after IOP-lowering treatments. This demonstrates the need for a better understanding of the pathogenesis of NTG and underlying mechanisms leading to neurodegeneration. Recent studies have found significant connections between NTG and cerebral manifestations, suggesting NTG as a neurodegenerative disease beyond the eye. Gaining a better understanding of NTG can potentially provide new Alzheimer's Disease diagnostics capabilities. This review identifies the epidemiology, current biomarkers, altered fluid dynamics, and cerebral and ocular manifestations to examine connections and discrepancies between the mechanisms of NTG and Alzheimer's Disease.

Exogenous monosodium glutamate exacerbates lipopolysaccharide-induced neurobehavioral deficits, oxidative damage, neuroinflammation, and cholinergic dysfunction in rat brain

Extensive experimental evidence points to neuroinflammation and oxidative stress as major pathogenic events that initiate and drive the neurodegenerative process. Monosodium glutamate (MSG) is a widely used food additive in processed foods known for its umami taste-enhancing properties. However, concerns about its potential adverse effects on the brain have been raised. Thus, the present study investigated the impact of MSG on lipopolysaccharide (LPS)-induced neurotoxicity in rat brains. Wistar rats weighing between 180 g and 200 g were randomly allocated into four groups: control (received distilled water), MSG (received 1.5 g/kg/day), LPS (received 250 µg/kg/day), and LPS + MSG (received LPS, 250 µg/kg, and MSG, 1.5 g/kg). LPS was administered intraperitoneally for 7 days while MSG was administered orally for 14 days. Our results showed that MSG exacerbated LPS-induced impairment in locomotor and exploratory activities in rats. Similarly, MSG exacerbated LPS-induced oxidative stress as evidenced by increased levels of malondialdehyde (MDA) with a concomitant decrease in levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione-s-transferase (GST) in the brain tissue. In addition, MSG potentiated LPS-induced neuroinflammation, as indicated by increased levels of pro-inflammatory cytokines such as interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) as well as myeloperoxidase (MPO) and nitric oxide (NO) in the brain. Moreover, MSG aggravated LPS-induced cholinergic dysfunction, as demonstrated by increased activity of acetylcholinesterase (AChE) in the brain. Further, we found a large number of degenerative neurons widespread in hippocampal CA1, CA3 regions, cerebellum, and cortex according to H&E staining. Taken together, our findings suggest that MSG aggravates LPS-induced neurobehavioral deficits, oxidative stress, neuroinflammation, cholinergic dysfunction, and neurodegeneration in rat brains.

Intracerebellar injection of monocytic immature myeloid cells prevents the adverse effects caused by stereotactic surgery in a model of cerebellar neurodegeneration

BACKGROUND

Myeloid-derived suppressor cells (MDSCs) constitute a recently discovered bone-marrow-derived cell type useful for dealing with neuroinflammatory disorders. However, these cells are only formed during inflammatory conditions from immature myeloid cells (IMCs) that acquire immunosuppressive activity, thus being commonly gathered from diseased animals. Then, to obtain a more clinically feasible source, we characterized IMCs directly derived from healthy bone marrow and proved their potential immunosuppressive activity under pathological conditions in vitro. We then explored their neuroprotective potential in a model of human cerebellar ataxia, the Purkinje Cell Degeneration (PCD) mouse, as it displays a well-defined neurodegenerative and neuroinflammatory process that can be also aggravated by invasive surgeries.

METHODS

IMCs were obtained from healthy bone marrow and co-cultured with activated T cells. The proliferation and apoptotic rate of the later were analyzed with Tag-it Violet. For in vivo studies, IMCs were transplanted by stereotactic surgery into the cerebellum of PCD mice. We also used sham-operated animals as controls of the surgical effects, as well as their untreated counterparts. Motor behavior of mice was assessed by rotarod test. The Purkinje cell density was measured by immunohistochemistry and cell death assessed with the TUNEL technique. We also analyzed the microglial phenotype by immunofluorescence and the expression pattern of inflammation-related genes by qPCR. Parametric tests were applied depending on the specific experiment: one or two way ANOVA and Student's T test.

RESULTS

IMCs were proven to effectively acquire immunosuppressive activity under pathological conditions in vitro, thus acting as MDSCs. Concerning in vivo studios, sham-operated PCD mice suffered detrimental effects in motor coordination, Purkinje cell survival and microglial activation. After intracranial administration of IMCs into the cerebellum of PCD mice, no special benefits were detected in the transplanted animals when compared to untreated mice. Nonetheless, this transplant almost completely prevented the impairments caused by the surgery in PCD mice, probably by the modulation of the inflammatory patterns.

CONCLUSIONS

Our work comprise two main translational findings: (1) IMCs can be directly used as they behave as MDSCs under pathological conditions, thus avoiding their gathering from diseased subjects; (2) IMCs are promising adjuvants when performing neurosurgery.

Anti-inflammatory and antioxidative actions of tacrolimus (FK506) on human microglial HMC3 cell line

Microglial cells are indispensable for the normal development and functioning of neurons in the central nervous system, where they play a crucial role in maintaining brain homeostasis by surveilling the microenvironment for signs of injury or stress and responding accordingly. However, in neurodegenerative diseases, the density and phenotypes of microglial cells undergo changes, leading to chronic activation and inflammation. Shifting the focus from neurons to microglia in drug discovery for neurodegenerative diseases has become an important therapeutic target. This study was aimed to investigate the potential of Tacrolimus (FK506) an FDA-approved calcineurin inhibitor, to modulate the pathology of neurodegenerative diseases through anti-inflammatory and antioxidative effects on microglial activation. The human microglia clone 3 (HMC3) cells were exposed to 1 μg/mL LPS in the presence and absence of doses of FK506. Survival rates of cells were determined using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) method. Morphological evaluation of cells showed that FK506 restored the normal morphology of activated microglia. Furthermore, FK506 treatment increases the total antioxidant capacity and reduces the total oxidative capacity, indicating its potential antioxidant effects. Data from ELISA and RT-PCR analyses showed that LPS abolished its promoting effects on the release of proinflammatory IL-1β and IL-6 cytokines in HMC3 cells, reflecting the anti-inflammatory effect of FK506. These findings support the idea that FK506 could be a promising therapeutic agent for neurodegenerative diseases by modulating microglial activation and reducing inflammation and oxidative stress.

Anti-Neuroinflammatory Effects of Arecae pericarpium on LPS-Stimulated BV2 Cells

Arecae pericarpium (AP), the fruit peel of the betel palm, is a traditional Oriental herbal medicine. AP is used to treat various diseases and conditions, such as ascites, edema, and urinary retention, in traditional Korean medicine. Recent studies have demonstrated its anti-obesity and antibacterial effects; however, its anti-neuroinflammatory effects have not yet been reported. Therefore, we investigated the anti-neuroinflammatory effects of AP on lipopolysaccharide (LPS)-stimulated mouse microglia in this study. To determine the anti-neuroinflammatory effects of AP on BV2 microglial cells, we examined the production of nitric oxide (NO) using Griess assay and assessed the mRNA expression levels of inflammatory mediators, such as inducible NO synthase (iNOS) and cyclooxygenase (COX)-2, and pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, using a real-time reverse transcription-polymerase chain reaction. Furthermore, we determined the levels of mitogen-activated protein kinases and IκBα via Western blotting to understand the regulating mechanisms of AP. AP treatment decreased NO production in LPS-stimulated BV2 cells. Additionally, AP suppressed the expression of iNOS and COX-2 and the production of pro-inflammatory cytokines. AP also inhibited the activation of p38 and nuclear factor-kappa B (NF-κB) in LPS-stimulated BV2 cells. Therefore, AP exerts anti-neuroinflammatory effects via inactivation of the p38 and NF-κB pathways.

Mesenchymal Stem Cell-Macrophage Crosstalk Provides Specific Exosomal Cargo to Direct Immune Response Licensing of Macrophages during Inflammatory Responses

Neurodegenerative diseases (NDDs) continue to be a significant healthcare problem. The economic and social implications of NDDs increase with longevity. NDDs are linked to neuroinflammation and activated microglia and astrocytes play a central role. There is a growing interest for stem cell-based therapy to deliver genes, and for tissue regeneration. The promise of mesenchymal stem cells (MSC) is based on their availability as off-the-shelf source, and ease of expanding from discarded tissues. We tested the hypothesis that MSC have a major role of resetting activated microglial cells. We modeled microglial cell lines by using U937 cell-derived M1 and M2 macrophages. We studied macrophage types, alone, or in a non-contact culture with MSCs. MSCs induced significant release of exosomes from both types of macrophages, but significantly more of the M1 type. RNA sequencing showed enhanced gene expression within the exosomes with the major changes linked to the inflammatory response, including cytokines and the purinergic receptors. Computational analyses of the transcripts supported the expected effect of MSCs in suppressing the inflammatory response of M1 macrophages. The inflammatory cargo of M1 macrophage-derived exosomes revealed involvement of cytokines and purinergic receptors. At the same time, the exosomes from MSC-M2 macrophages were able to reset the classical M2 macrophages to more balanced inflammation. Interestingly, we excluded transfer of purinergic receptor transcripts from the co-cultured MSCs by analyzing these cells for the identified purinergic receptors. Since exosomes are intercellular communicators, these findings provide insights into how MSCs may modulate tissue regeneration and neuroinflammation.

Regulation of Pain Perception by Microbiota in Parkinson Disease

Pain perception involves current stimulation in peripheral nociceptive nerves and the subsequent stimulation of postsynaptic excitatory neurons in the spinal cord. Importantly, in chronic pain, the neural activity of both peripheral nociceptors and postsynaptic neurons in the central nervous system is influenced by several inflammatory mediators produced by the immune system. Growing evidence has indicated that the commensal microbiota plays an active role in regulating pain perception by either acting directly on nociceptors or indirectly through the modulation of the inflammatory activity on immune cells. This symbiotic relationship is mediated by soluble bacterial mediators or intrinsic structural components of bacteria that act on eukaryotic cells, including neurons, microglia, astrocytes, macrophages, T cells, enterochromaffin cells, and enteric glial cells. The molecular mechanisms involve bacterial molecules that act directly on neurons, affecting their excitability, or indirectly on non-neuronal cells, inducing changes in the production of proinflammatory or anti-inflammatory mediators. Importantly, Parkinson disease, a neurodegenerative and inflammatory disorder that affects mainly the dopaminergic neurons implicated in the control of voluntary movements, involves not only a motor decline but also nonmotor symptomatology, including chronic pain. Of note, several recent studies have shown that Parkinson disease involves a dysbiosis in the composition of the gut microbiota. In this review, we first summarize, integrate, and classify the molecular mechanisms implicated in the microbiota-mediated regulation of chronic pain. Second, we analyze the changes on the commensal microbiota associated to Parkinson disease and propose how these changes affect the development of chronic pain in this pathology. SIGNIFICANCE STATEMENT: The microbiota regulates chronic pain through the action of bacterial signals into two main locations: the peripheral nociceptors and the postsynaptic excitatory neurons in the spinal cord. The dysbiosis associated to Parkinson disease reveals increased representation of commensals that potentially exacerbate chronic pain and reduced levels of bacteria with beneficial effects on pain. This review encourages further research to better understand the signals involved in bacteria-bacteria and bacteria-host communication to get the clues for the development of probiotics with therapeutic potential.

Analyzing Facial Asymmetry in Alzheimer's Dementia Using Image-Based Technology

Several studies have demonstrated accelerated brain aging in Alzheimer's dementia (AD). Previous studies have also reported that facial asymmetry increases with age. Because obtaining facial images is much easier than obtaining brain images, the aim of this work was to investigate whether AD exhibits accelerated aging patterns in facial asymmetry. We developed new facial asymmetry measures to compare Alzheimer's patients with healthy controls. A three-dimensional camera was used to capture facial images, and 68 facial landmarks were identified using an open-source machine-learning algorithm called OpenFace. A standard image registration method was used to align the three-dimensional original and mirrored facial images. This study used the registration error, representing landmark superimposition asymmetry distances, to examine 29 pairs of landmarks to characterize facial asymmetry. After comparing the facial images of 150 patients with AD with those of 150 age- and sex-matched non-demented controls, we found that the asymmetry of 20 landmarks was significantly different in AD than in the controls (p < 0.05). The AD-linked asymmetry was concentrated in the face edge, eyebrows, eyes, nostrils, and mouth. Facial asymmetry evaluation may thus serve as a tool for the detection of AD.

Peripheral Inflammatory Markers in Autism Spectrum Disorder and Attention Deficit/Hyperactivity Disorder at Adolescent Age

Autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD) are associated with immune dysregulation. We aimed to estimate the pro- and anti-inflammatory activity/balance in ASD and ADHD patients at a little-studied adolescent age with respect to sex. We evaluated 20 ASD patients (5 girls, average age: 12.4 ± 1.9 y), 20 ADHD patients (5 girls, average age: 13.4 ± 1.8 y), and 20 age- and gender-matched controls (average age: 13.2 ± 1.9 y). The evaluated parameters included (1) white blood cells (WBCs), neutrophils, monocytes, lymphocytes, platelets, platelet distribution width (PDW), mean platelet volume, and derived ratios, as well as (2) cytokines-interferon-gamma, interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, and IL-10, tumor necrosis factor-alpha (TNF-α), and derived profiles and ratios. ASD adolescents showed higher levels of WBC, monocytes, IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, and IL-10, macrophages (M)1 profile, and anti-inflammatory profile than the controls, with ASD males showing higher monocytes, IL-6 and IL-10, anti-inflammatory profile, and a lower T-helper (Th)1/Th2+T-regulatory cell ratio than control males. The ADHD adolescents showed higher levels of PDW, IL-1β and IL-6, TNF-α, M1 profile, proinflammatory profile, and pro-/anti-inflammatory ratio than the controls, with ADHD females showing a higher TNF-α and pro-/anti-inflammatory ratio than the control females and ADHD males showing higher levels of IL-1β and IL-6, TNF-α, and M1 profile than the control males. Immune dysregulation appeared to be different for both neurodevelopmental disorders in adolescence.

Looking to the Future of the Role of Macrophages and Extracellular Vesicles in Neuroinflammation in ALS

Neuroinflammation is a common pathological feature of amyotrophic lateral sclerosis (ALS). Although scientific evidence to date does not allow defining neuroinflammation as an ALS trigger, its role in exacerbating motor neuron (MNs) degeneration and disease progression is attracting research interest. Activated CNS (Central Nervous System) glial cells, proinflammatory peripheral and infiltrated T lymphocytes and monocytes/macrophages, as well as the immunoreactive molecules they release, represent the active players for the role of immune dysregulation enhancing neuroinflammation. The crosstalk between the peripheral and CNS immune cells significantly correlates with the survival of ALS patients since the modification of peripheral macrophages can downregulate inflammation at the periphery along the nerves and in the CNS. As putative vehicles for misfolded protein and inflammatory mediators between cells, extracellular vesicles (EVs) have also drawn particular attention in the field of ALS. Both CNS and peripheral immune cells release EVs, which are able to modulate the behavior of neighboring recipient cells; unfortunately, the mechanisms involved in EVs-mediated communication in neuroinflammation remain unclear. This review aims to synthesize the current literature regarding EV-mediated cell-to-cell communication in the brain under ALS, with a particular point of view on the role of peripheral macrophages in responding to inflammation to understand the biological process and exploit it for ALS management.

Prior exposure to stress exacerbates neuroinflammation and causes long-term behavior changes in sepsis

Background

Neuroinflammation can occur during sepsis and is now regarded as the main mechanism underlying various related central nervous system (CNS) disorders. Another well-known factor causing neuroinflammation is psychological stress. In the current study, we examined the effects of prior exposure to stress on sepsis-induced neuroinflammation and CNS symptoms.

Experimental procedure

Balb/c mice were subjected to wet bedding stress for 2 days, then lipopolysaccharide (LPS) was intraperitoneally administered. For examining the neuroinflammation, the expression of proinflammatory cytokines and NF-κB activity in the brain was analyzed by RT-PCR and ELISA-based assay. Additionally, immunohistochemical study using Iba-1 was performed. Finally, behavior tests were examined one month after LPS treatment.

Result and conclusion

Stress exposure induced the upregulation of IL-1β, IL-6 and TNFα mRNA in the cerebral cortex 4 h after LPS administration. Suggesting an underlying mechanism, LPS-induced NF-κB activation was significantly upregulated with stress in the brain. Histologically, microglia in the cerebral cortex were reactive and became more abundant with stress, while these effects were further increased with LPS injection. Behavioral analysis conducted showed a significant increase of anxiety-like behaviors in the stressed mice. These results suggest that prior exposure to stress exacerbates neuroinflammation during sepsis and induces long-term behavior changes.

Neuroprotection by Abdominal Ultrasound in Lipopolysaccharide-Induced Systemic Inflammation

Systemic inflammation is associated with intestinal inflammation and neuroinflammation by imbalancing the gut-brain axis. Low-intensity pulsed ultrasound (LIPUS) has neuroprotective and anti-inflammatory effects. This study explored LIPUS's neuroprotective effects against lipopolysaccharide (LPS)-induced neuroinflammation through transabdominal stimulation. Male C57BL/6J mice were intraperitoneally injected with LPS (0.75 mg/kg) daily for seven days, and abdominal LIPUS was applied to the abdominal area for 15 min/day during the last six days. One day after the last LIPUS treatment, biological samples were collected for microscopic and immunohistochemical analysis. Histological examination showed that LPS administration leads to tissue damage in the colon and brain. Transabdominal LIPUS stimulation attenuated colonic damage, reducing histological score, colonic muscle thickness, and villi shortening. Furthermore, abdominal LIPUS reduced hippocampal microglial activation (labeled by ionized calcium-binding adaptor molecule-1 [Iba-1]) and neuronal cell loss (labeled by microtubule-associated protein 2 [MAP2]). Moreover, abdominal LIPUS attenuated the number of apoptotic cells in the hippocampus and cortex. Altogether, our results indicate that abdominal LIPUS stimulation attenuates LPS-induced colonic inflammation and neuroinflammation. These findings provide new insights into the treatment strategy for neuroinflammation-related brain disorders and may facilitate method development through the gut-brain axis pathway.

Escalating Bi-Directional Feedback Loops between Proinflammatory Microglia and Mitochondria in Ageing and Post-Diagnosis of Parkinson's Disease

Parkinson's disease (PD) is a chronic and progressive age-related neurodegenerative disease affecting up to 3% of the global population over 65 years of age. Currently, the underlying physiological aetiology of PD is unknown. However, the diagnosed disorder shares many common non-motor symptoms associated with ageing-related neurodegenerative disease progression, such as neuroinflammation, microglial activation, neuronal mitochondrial impairment, and chronic autonomic nervous system dysfunction. Clinical PD has been linked to many interrelated biological and molecular processes, such as escalating proinflammatory immune responses, mitochondrial impairment, lower adenosine triphosphate (ATP) availability, increasing release of neurotoxic reactive oxygen species (ROS), impaired blood brain barrier integrity, chronic activation of microglia, and damage to dopaminergic neurons consistently associated with motor and cognitive decline. Prodromal PD has also been associated with orthostatic hypotension and many other age-related impairments, such as sleep disruption, impaired gut microbiome, and constipation. Thus, this review aimed to present evidence linking mitochondrial dysfunction, including elevated oxidative stress, ROS, and impaired cellular energy production, with the overactivation and escalation of a microglial-mediated proinflammatory immune response as naturally occurring and damaging interlinked bidirectional and self-perpetuating cycles that share common pathological processes in ageing and PD. We propose that both chronic inflammation, microglial activation, and neuronal mitochondrial impairment should be considered as concurrently influencing each other along a continuum rather than as separate and isolated linear metabolic events that affect specific aspects of neural processing and brain function.

Degeneracy in epilepsy: multiple routes to hyperexcitable brain circuits and their repair

Due to its complex and multifaceted nature, developing effective treatments for epilepsy is still a major challenge. To deal with this complexity we introduce the concept of degeneracy to the field of epilepsy research: the ability of disparate elements to cause an analogous function or malfunction. Here, we review examples of epilepsy-related degeneracy at multiple levels of brain organisation, ranging from the cellular to the network and systems level. Based on these insights, we outline new multiscale and population modelling approaches to disentangle the complex web of interactions underlying epilepsy and to design personalised multitarget therapies.

Pathological mechanisms of neuroimmune response and multitarget disease-modifying therapies of mesenchymal stem cells in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by the degeneration of dopaminergic neurons in the substantia nigra (SN); the etiology and pathological mechanism of the disease are still unclear. Recent studies have shown that the activation of a neuroimmune response plays a key role in the development of PD. Alpha-synuclein (α-Syn), the primary pathological marker of PD, can gather in the SN and trigger a neuroinflammatory response by activating microglia which can further activate the dopaminergic neuron's neuroimmune response mediated by reactive T cells through antigen presentation. It has been shown that adaptive immunity and antigen presentation processes are involved in the process of PD and further research on the neuroimmune response mechanism may open new methods for its prevention and therapy. While current therapeutic regimens are still focused on controlling clinical symptoms, applications such as immunoregulatory strategies can delay the symptoms and the process of neurodegeneration. In this review, we summarized the progression of the neuroimmune response in PD based on recent studies and focused on the use of mesenchymal stem cell (MSC) therapy and challenges as a strategy of disease-modifying therapy with multiple targets.

Bacillus Calmette-Guérin Tokyo-172 vaccine provides age-related neuroprotection in actively induced and spontaneous experimental autoimmune encephalomyelitis models

Multiple sclerosis is the most common immune-mediated disorder affecting the central nervous system in young adults but still has no cure. Bacillus Calmette-Guérin (BCG) vaccine is reported to have non-specific anti-inflammatory effects and therapeutic benefits in autoimmune disorders including multiple sclerosis. However, the precise mechanism of action of BCG and the host immune response to it remain unclear. In this study, we aimed to investigate the efficacy of the BCG Tokyo-172 vaccine in suppressing experimental autoimmune encephalomyelitis (EAE). Groups of young and mature adult female C57BL/6J mice were BCG-vaccinated 1 month prior or 6 days after active EAE induction using myelin oligodendrocyte glycoprotein (MOG)35-55 peptide. Another group of 2D2 TCRMOG transgenic female mice was BCG-vaccinated before and after the onset of spontaneous EAE. BCG had an age-associated protective effect against active EAE only in wild-type mice vaccinated 1 month before EAE induction. Furthermore, the incidence of spontaneous EAE was significantly lower in BCG vaccinated 2D2 mice than in non-vaccinated controls. Protection against EAE was associated with reduced splenic T-cell proliferation in response to MOG35-55 peptide together with high frequency of CD8+ interleukin-10-secreting T cells in the spleen. In addition, microglia and astrocytes isolated from BCG-vaccinated mice showed polarization to anti-inflammatory M2 and A2 phenotypes, respectively. Our data provide new insights into the cell-mediated and humoral immune mechanisms underlying BCG vaccine-induced neuroprotection, potentially useful for developing better strategies for the treatment of MS.

Activation of retinal glial cells contributes to the degeneration of ganglion cells in experimental glaucoma

Elevation of intraocular pressure (IOP) is a major risk factor for neurodegeneration in glaucoma. Glial cells, which play an important role in normal functioning of retinal neurons, are well involved into retinal ganglion cell (RGC) degeneration in experimental glaucoma animal models generated by elevated IOP. In response to elevated IOP, mGluR I is first activated and Kir4.1 channels are subsequently inhibited, which leads to the activation of Müller cells. Müller cell activation is followed by a complex process, including proliferation, release of inflammatory and growth factors (gliosis). Gliosis is further regulated by several factors. Activated Müller cells contribute to RGC degeneration through generating glutamate receptor-mediated excitotoxicity, releasing cytotoxic factors and inducing microglia activation. Elevated IOP activates microglia, and following morphological and functional changes, these cells, as resident immune cells in the retina, show adaptive immune responses, including an enhanced release of pro-inflammatory factors (tumor neurosis factor-α, interleukins, etc.). These ATP and Toll-like receptor-mediated responses are further regulated by heat shock proteins, CD200R, chemokine receptors, and metabotropic purinergic receptors, may aggravate RGC loss. In the optic nerve head, astrogliosis is initiated and regulated by a complex reaction process, including purines, transmitters, chemokines, growth factors and cytokines, which contributes to RGC axon injury through releasing pro-inflammatory factors and changing extracellular matrix in glaucoma. The effects of activated glial cells on RGCs are further modified by the interplay among different types of glial cells. This review is concluded by presenting an in-depth discussion of possible research directions in this field in the future.

Tissue-resident immune cells in the pathogenesis of multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system (CNS) in which genetic and environmental factors contribute to disease progression. Both innate and adaptive immune cells, including T cells, B cells, activated macrophages and microglia, have been identified to be involved in the pathogenesis of MS, leading to the CNS inflammation, neurodegeneration and demyelination. In recent years, there has been considerable progress in understanding the contribution of tissue-resident immune cells in the pathogenesis of MS.

METHODS

We performed a keyword-based search in PubMed database. We combined "multiple sclerosis" with keywords, such as tissue-resident memory T cells, microglia to search for relevant literatures in PubMed.

RESULTS AND CONCLUSION

In this review, we comprehensively describe the characteristics of tissue-resident memory T cells and microglia, summarize their role in the pathogenesis of MS, and discuss their interaction with other immune cells in the CNS.

Role of the Peli1-RIPK1 Signaling Axis in Methamphetamine-Induced Neuroinflammation

Severe neurological inflammation is one of the main symptoms of methamphetamine (meth)-induced brain injury. Studies have demonstrated that meth exposure facilitates neuroinflammation via Pellino E3 ubiquitin protein ligase 1 (Peli1)-mediated signaling. However, the involved mechanisms remain incompletely understood. Herein, we used Peli1^-/- mice and Peli1-knockdown microglial BV2 cells to decipher the roles of Peli1 and downstream signaling in meth-induced neuroinflammation. After meth administration for seven consecutive days, Peli1^-/- mice exhibited better learning and memory behavior and dramatically lower interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6 levels than wild-type mice. Moreover, in vitro experiments revealed that Peli1 knockdown significantly attenuated the meth-induced upregulation of cytokines. Besides, meth markedly activated and increased the levels of receptor-interacting protein kinase 1 (RIPK1), and Peli1 knockout or knockdown prevented these effects, indicating that RIPK1 participated in meth-induced Peli1-mediated inflammation. Specifically, treating the cells with necrostatin-1(Nec-1), an antagonist of RIPK1, remarkably inhibited the meth-induced increase in IL-1β, TNF-α, and IL-6 expression, confirming the involvement of RIPK1 in Peli1-mediated neuroinflammation. Finally, meth induced a dramatic transfer of the mixed lineage kinase domain-like protein, a downstream effector of RIRK1, to the cell membrane, disrupting membrane integrity and causing cytokine excretion. Therefore, targeting the Peli1-RIPK1 signaling axis is a potentially valid therapeutic approach against meth-induced neuroinflammation.

Lymphocyte deficiency alters the transcriptomes of oligodendrocytes, but not astrocytes or microglia

Though the brain was long characterized as an immune-privileged organ, findings in recent years have shown extensive communications between the brain and peripheral immune cells. We now know that alterations in the peripheral immune system can affect the behavioral outputs of the central nervous system, but we do not know which brain cells are affected by the presence of peripheral immune cells. Glial cells including microglia, astrocytes, oligodendrocytes, and oligodendrocyte precursor cells (OPCs) are critical for the development and function of the central nervous system. In a wide range of neurological and psychiatric diseases, the glial cell state is influenced by infiltrating peripheral lymphocytes. However, it remains largely unclear whether the development of the molecular phenotypes of glial cells in the healthy brain is regulated by lymphocytes. To answer this question, we acutely purified each type of glial cell from immunodeficient Rag2-/- mice. Interestingly, we found that the transcriptomes of microglia, astrocytes, and OPCs developed normally in Rag2-/- mice without reliance on lymphocytes. In contrast, there are modest transcriptome differences between the oligodendrocytes from Rag2-/- and control mice. Furthermore, the subcellular localization of the RNA-binding protein Quaking, is altered in oligodendrocytes. These results demonstrate that the molecular attributes of glial cells develop largely without influence from lymphocytes and highlight potential interactions between lymphocytes and oligodendrocytes.

Blood Biomarkers in Patients with Parkinson's Disease: A Review in Context of Anesthetic Care

Parkinson's disease (PD) is the second most common inflammatory neurodegenerative disorder after dementia. Preclinical and epidemiological data strongly suggest that chronic neuroinflammation slowly induces neuronal dysfunction. Activated microglia secrete several neurotoxic substances, such as chemokines and proinflammatory cytokines, which may promote blood-brain barrier (BBB) permeabilization. CD4⁺ T cells comprise proinflammatory cells such as T helper (Th) 1 and Th17 cells, as well as anti-inflammatory cells such as Th2 and T regulatory cells (Tregs). Th1 and Th17 cells can be detrimental to dopamine neurons, whereas Th2 and Tregs are neuroprotective. The results of studies on the serum levels of cytokines such as IFN-γ and TNF-α secreted by Th1 T cells, IL-8 and IL-10 secreted by Th2 T cells, and IL-17 secreted by Th17 cells in PD patients are not uniform. In addition, the relationships between serum cytokine levels and motor and non-motor symptoms of PD are controversial. Surgical stress and anesthesia induce inflammatory responses by disturbing the balance between pro- and anti-inflammatory cytokines, which may exacerbate the neuroinflammatory response in PD patients. Here we review studies on blood inflammatory biomarkers in PD patients and discuss the roles of surgery and anesthesia in PD progression.

Beneficial effects of tannic acid on comorbid anxiety in cecal ligation and puncture-induced sepsis in rats and potential underlying mechanisms

Sepsis-associated encephalopathy (SAE), a neurological dysfunction caused by sepsis, is the most common complication among septic ICU patients. Given the major role of inflammation in the pathophysiology of sepsis-induced anxiety, an extreme and early manifestation of SAE, the present study examined whether tannic acid, as an anti-inflammatory agent, has anxiolytic effects in cecal ligation and puncture (CLP)-induced sepsis. Forty male Wistar rats were assigned to four groups: (1) sham; (2) sham + tannic acid; (3) sepsis and (4) sepsis + tannic acid. Sepsis was induced by cecal ligation and puncture model. Animals in the sham + tannic acid and sepsis + tannic acid groups received tannic acid (20 mg/kg, i.p.), 6, 12, and 18 h after the sepsis induction. Twenty-four hours after the sepsis induction, systolic blood pressure and sepsis score were assessed. Anxiety-related behaviors were evaluated using elevated plus-maze and dark-light transition tests. Moreover, inflammatory markers (TNF-α and IL-6) and oxidative stress parameters (MDA and SOD) were measured in the brain tissue while protein levels (GABAA receptors and IL-1β) were assessed in the hippocampus. Administration of tannic acid significantly improved sepsis score and hypotension induced by sepsis. Anxiety-related behaviors showed a significant decrease in the sepsis + tannic acid group compared to the sepsis group. Tannic acid caused a significant decrease in the brain inflammatory markers and a remarkable improvement in the brain oxidative status compared to the septic rats. Tannic acid prevented animals from decreasing GABAA receptors and increasing IL-1β protein levels in the hippocampus compared to the sepsis group. This study indicated that tannic acid mitigated anxiety-related behaviors through decreasing inflammation and oxidative stress and positively modifying IL-1β/GABAA receptor pathway. Therefore, tannic acid shows promise as an efficacious treatment for comorbid anxiety in septic patients.

TiO2-Nanowired Delivery of Chinese Extract of Ginkgo biloba EGb-761 and Bilobalide BN-52021 Enhanced Neuroprotective Effects of Cerebrolysin Following Spinal Cord Injury at Cold Environment

Military personnel during combat or peacekeeping operations are exposed to extreme climates of hot or cold environments for longer durations. Spinal cord injury is quite common in military personnel following central nervous system (CNS) trauma indicating a possibility of altered pathophysiological responses at different ambient temperatures. Our previous studies show that the pathophysiology of brain injury is exacerbated in animals acclimated to cold (5 °C) or hot (30 °C) environments. In these diverse ambient temperature zones, trauma exacerbated oxidative stress generation inducing greater blood-brain barrier (BBB) permeability and cell damage. Extracts of Ginkgo biloba EGb-761 and BN-52021 treatment reduces brain pathology following heat stress. This effect is further improved following TiO₂ nanowired delivery in heat stress in animal models. Several studies indicate the role of EGb-761 in attenuating spinal cord induced neuronal damages and improved functional deficit. This is quite likely that these effects are further improved following nanowired delivery of EGb-761 and BN-52021 with cerebrolysin-a balanced composition of several neurotrophic factors and peptide fragments in spinal cord trauma. In this review, TiO₂ nanowired delivery of EGb-761 and BN-52021 with nanowired cerebrolysin is examined in a rat model of spinal cord injury at cold environment. Our results show that spinal cord injury aggravates cord pathology in cold-acclimated rats and nanowired delivery of EGb-761 and BN-52021 with cerebrolysin significantly induced superior neuroprotection, not reported earlier.

MicroRNA-451 Attenuates the Inflammatory Response of Activated Microglia by Downregulating Nucleotide Binding Oligomerization Domain-Like Receptor Protein 3

BACKGROUND

Spinal cord injury is the most common problem encountered during spinal surgery. After the initial trauma, the disruption of the blood-brain barrier and subsequent microglia activation result in extensive inflammatory responses. Inflammasomes are large protein complexes that are essential during inflammation. One of the most studied inflammasome components, nucleotide binding oligomerization domain-like receptor protein 3 (NLRP; nucleotide binding oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing 3), is widely expressed in the central nervous system. Previous research has shown that microRNA-451 (miR-451) might play a role in regulating inflammatory conditions.

METHODS

Using bioinformatics analysis, we found that NLRP3 is a direct target of miR-451. This in silico prediction was confirmed using dual-luciferase reporter gene assays. To further demonstrate that miR-451 influenced microglial NLRP3 production, we activated microglial cells with lipopolysaccharides.

RESULTS

Activating microglial cells with lipopolysaccharides resulted in the production of NLRP3 inflammasomes and the secretion of the proinflammatory cytokines interleukin-1β and interleukin-18. We were able to demonstrate that overexpression of miR-451 suppressed this NLRP3-induced proinflammatory cascade of events.

CONCLUSIONS

Our findings have highlighted the potential anti-inflammatory role of miR-451 in reducing the secondary neuronal damage after spinal cord injury.

DiHuangYin decoction protects dopaminergic neurons in a Parkinson's disease model by alleviating peripheral inflammation

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disease, which brings increasing threaten for human health and is still lacking of satisfied treatment. Recently, numerous studies have also demonstrated the effect of particular subsets of CD4+ T cells on PD pathology. Th17 cells played an important role in the pathogenesis of PD. Traditional Chinese medicine has been widely used to treat PD clinically, and has a tremendous potential in clinical drug development.

PURPOSE

The aim of this study was to verify the therapeutic effects of DHY on PD mice model, and investigate the underlying molecular mechanisms.

METHODS

Herein, we verified the effects of a traditional Chinese medicine formula, named DiHuangYin (DHY), on the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced mouse model of PD through behavioral and histopathological tests. High-resolution mass spectrometry combined with molecular networking was applied for substance profiling of DHY. Based on the chemical compositions of DHY, network pharmacology was performed. Immunofluorescence and ELISA were used to evaluate the expressions of cytokines in peripheral immune system. qPCR and immunofluorescence were used to detect the inflammation infiltration of central nervous system.

RESULTS

DHY improves the motor function and prevents the loss of dopaminergic neurons in the MPTP induced mouse model of PD. 118 components of DHY were identified or tentatively characterized based on the MS/MS data and molecular networking. Network pharmacology suggested IL-17 signaling pathway and neuroactive ligand-receptor interaction as the important targets. Compared to the MPTP-intoxicated mice, the DHY group showed a decreased number of Th17 cells from splenocytes and a decreased level of IL-17A in the serum. On the other hand, less inflammatory infiltration was found in the midbrain of DHY treatment mice which might be associated with the attenuated peripheral inflammation.

CONCLUSIONS

Though the underlying pharmacological mechanism of DHY is still lacking, we provided evidence that DHY decoction could protect dopaminergic neurons by mitigating peripheral inflammation.

Interleukin 22 and its association with neurodegenerative disease activity

It is worth noting that neuroinflammation is well recognized as a symptom of neurodegenerative diseases (NDs). The regulation of neuroinflammation becomes an attractive focus for innovative ND treatment technologies. There is evidence that IL-22 is associated with the development and progression of a wide assortment of NDs. For example, IL-22 can activate glial cells, causing them to generate pro-inflammatory cytokines and encourage lymphocyte infiltration in the brain. IL-22 mRNA is highly expressed in Alzheimer’s disease (AD) patients, and a high expression of IL-22 has also been detected in the brains of patients with other NDs. We examine the role of IL-22 in the development and treatment of NDs in this review, and we believe that IL-22 has therapeutic potential in these diseases.

A microengineered Brain-Chip to model neuroinflammation in humans

Species differences in brain and blood-brain barrier (BBB) biology hamper the translation of findings from animal models to humans, impeding the development of therapeutics for brain diseases. Here, we present a human organotypic microphysiological system (MPS) that includes endothelial-like cells, pericytes, glia, and cortical neurons and maintains BBB permeability at in vivo relevant levels. This human Brain-Chip engineered to recapitulate critical aspects of the complex interactions that mediate neuroinflammation and demonstrates significant improvements in clinical mimicry compared to previously reported similar MPS. In comparison to Transwell culture, the transcriptomic profiling of the Brain-Chip displayed significantly advanced similarity to the human adult cortex and enrichment in key neurobiological pathways. Exposure to TNF-α recreated the anticipated inflammatory environment shown by glia activation, increased release of proinflammatory cytokines, and compromised barrier permeability. We report the development of a robust brain MPS for mechanistic understanding of cell-cell interactions and BBB function during neuroinflammation.

Exacerbated immune response of the brain to peripheral immune challenge in post-septic mice

BACKGROUND

Mounting evidence indicates that sepsis can induce long-lasting brain dysfunction. Recently, it has been proposed that the brain may become more sensitive to systemic inflammation if microglial cells are already primed. Microglial priming has been demonstrated in aging, traumatic brain injury, and neurodegenerative diseases. There is evidence suggesting that systemic inflammation may also prime microglia. This study aimed to investigate the brain's response to a second immune challenge in sepsis survivors and the possible role of microglial priming.

METHODS

Adult BALB/c mice were intraperitoneally (ip) injected with 5 mg/kg lipopolysaccharide (LPS) for sepsis induction. One month later, mice received a second immune challenge (LPS, 0.33 mg/kg). A cohort of mice was sacrificed 2 h post-LPS injection to measure inflammatory mediators mRNA expression. The second cohort of mice was tested on a battery of behavioral tests and then sacrificed, and brain tissues were removed for biochemical analyses.

RESULTS

Results showed that in septic mice, secondary LPS challenge induced heightened neuroinflammation compared to the control mice, as evident by a significant increase of IL-1β, TNF-α, and iNOS mRNA expression. In the immunochallenged septic mice, the anti-inflammatory cytokine IL-10 expression was also significantly increased compared to the control mice. Sepsis induction significantly disrupted the recognition ability in the novel object recognition, but the second immune challenge had no significant effect. However, immunochallenged septic mice exhibited more anxiety-like behavior in the marble burying task and intensive depressive-like behavior in the forced swim test. Additionally, the second immune challenge reduced arginase-1 levels in septic but not control mice. On the other hand, CIITA levels were increased more significantly in the LPS injected control mice compared to septic mice. Neither sepsis nor the second immune challenge significantly affected inhibitory avoidance behavior and Aβ_1-42 levels in brain tissue.

CONCLUSION

Our finding suggests that low-grade immune challenge can induce exacerbated behavioral change and exaggerated inflammatory response in the brain of post-septic mice.

Retinal Changes in Astrocytes and Müller Glia in a Mouse Model of Laser-Induced Glaucoma: A Time-Course Study

Macroglia (astrocytes and Müller glia) may play an important role in the pathogenesis of glaucoma. In a glaucoma mouse model, we studied the effects of unilateral laser-induced ocular hypertension (OHT) on macroglia in OHT and contralateral eyes at different time points after laser treatment (1, 3, 5, 8 and 15 days) using anti-GFAP and anti-MHC-II, analyzing the morphological changes, GFAP-labelled retinal area (GFAP-PA), and GFAP and MHC-II immunoreactivity intensities ((GFAP-IRI and MHC-II-IRI)). In OHT and contralateral eyes, with respect to naïve eyes, at all the time points, we found the following: (i) astrocytes with thicker somas and more secondary processes, mainly in the intermediate (IR) and peripheral retina (PR); (ii) astrocytes with low GFAP-IRI and only primary processes near the optic disc (OD); (iii) an increase in total GFAP-RA, which was higher at 3 and 5 days, except for at 15 days; (iv) an increase in GFAP-IRI in the IR and especially in the PR; (v) a decrease in GFAP-IRI near the OD, especially at 1 and 5 days; (vi) a significant increase in MHC-II-IRI, which was higher in the IR and PR; and (vii) the Müller glia were GFAP+ and MHC-II+. In conclusion, in this model of glaucoma, there is a bilateral macroglial activation maintained over time involved in the inflammatory glaucoma process.

A Dual Anti-Inflammatory and Anti-Proliferative 3-Styrylchromone Derivative Synergistically Enhances the Anti-Cancer Effects of DNA-Damaging Agents on Colon Cancer Cells by Targeting HMGB1-RAGE-ERK1/2 Signaling

The current anti-cancer treatments are not enough to eradicate tumors, and therefore, new modalities and strategies are still needed. Most tumors generate an inflammatory tumor microenvironment (TME) and maintain the niche for their development. Because of the critical role of inflammation via high-mobility group box 1 (HMGB1)–receptor for advanced glycation end-products (RAGE) signaling pathway in the TME, a novel compound possessing both anti-cancer and anti-inflammatory activities by suppressing the HMGB1-RAGE axis provides an effective strategy for cancer treatment. A recent work of our group found that some anti-cancer 3-styrylchromones have weak anti-inflammatory activities via the suppression of this axis. In this direction, we searched such anti-cancer molecules possessing potent anti-inflammatory activities and discovered 7-methoxy-3-hydroxy-styrylchromone (C6) having dual suppressive activities. Mechanism-of-action studies revealed that C6 inhibited the increased phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) under the stimulation of HMGB1-RAGE signaling and thereby suppressed cytokine production in macrophage-like RAW264.7 cells. On the other hand, in colorectal cancer HCT116 cells, C6 inhibited the activation of ERK1/2, cyclin-dependent kinase 1, and AKT, down-regulated the protein level of XIAP, and up-regulated pro-apoptotic Bax and caspase-3/7 expression. These alterations are suggested to be involved in the C6-induced suppression of cell cycle/proliferation and initiation of apoptosis in the cancer cells. More importantly, in cancer cells, the treatment of C6 potentiates the anti-cancer effects of DNA-damaging agents. Thus, C6 may be a promising lead for the generation of a novel class of cancer therapeutics.

A Comprehensive Review on Preclinical Evidence Based Neuroprotective Potential of Bacopa Monnieri Against Parkinson's Disease

Parkinson's diseaseis a chronic and gradually progressive neurodegenerative disorder triggered due to the loss of dopamine-releasing neurons in the region of substantianigra pars compacta characterized by the motor symptoms such as tremor, bradykinesia, akinesia, and postural instability. Proteinopathies, mitochondrial dysfunction induced dopaminergic neuronal deterioration, and gene mutations arethe hallmarks of Parkinson's disease. The bioactive components of Brahmi such as Bacoside A, Bacoside B, and Bacosaponins, belong to various chemical families. Brahmi's neuroprotective role includes reducing neuronal oxidative stress, dopaminergic neuronal degeneration, mitochondrial dysfunction, inflammation, aggregation inhibition of α-synuclein, and improvement of cognitive and learning behaviour. Researchers found that Bacopa monnieri significantly increased brain levels of glutathione, vitamin C, vitamin E, and vitamin A in rats exposed to cigarette smoke. Brahmi has a potent antioxidant property and neuroprotective effects against PD that help reduce oxidative stress, neuroinflammation and enhance the dopamine level. The review collates all the preclinical studies that prove the beneficial neuroprotective effect of Brahmi for treating PD.

Microbiota in neuroinflammation and synaptic dysfunction: a focus on Alzheimer's disease

BACKGROUND

The implication of gut microbiota in the control of brain functions in health and disease is a novel, currently emerging concept. Accumulating data suggest that the gut microbiota exert its action at least in part by modulating neuroinflammation. Given the link between neuroinflammatory changes and neuronal activity, it is plausible that gut microbiota may affect neuronal functions indirectly by impacting microglia, a key player in neuroinflammation. Indeed, increasing evidence suggests that interplay between microglia and synaptic dysfunction may involve microbiota, among other factors. In addition to these indirect microglia-dependent actions of microbiota on neuronal activity, it has been recently recognized that microbiota could also affect neuronal activity directly by stimulation of the vagus nerve.

MAIN MESSAGES

The putative mechanisms of the indirect and direct impact of microbiota on neuronal activity are discussed by focusing on Alzheimer's disease, one of the most studied neurodegenerative disorders and the prime cause of dementia worldwide. More specifically, the mechanisms of microbiota-mediated microglial alterations are discussed in the context of the peripheral and central inflammation cross-talk. Next, we highlight the role of microbiota in the regulation of humoral mediators of peripheral immunity and their impact on vagus nerve stimulation. Finally, we address whether and how microbiota perturbations could affect synaptic neurotransmission and downstream cognitive dysfunction.

CONCLUSIONS

There is strong increasing evidence supporting a role for the gut microbiome in the pathogenesis of Alzheimer's disease, including effects on synaptic dysfunction and neuroinflammation, which contribute to cognitive decline. Putative early intervention strategies based on microbiota modulation appear therapeutically promising for Alzheimer's disease but still require further investigation.

Microglia and HPA axis in depression: An overview of participation and relationship

Objectives: This narrative review article provides an overview on the involvement of microglia and the hypothalamic-pituitary-adrenal (HPA) axis in the pathophysiology of depression, as well investigates the mutual relationship between these two entities: how microglial activation can contribute to the dysregulation of the HPA axis, and vice versa.Methods: Relevant studies and reviews already published in the Pubmed electronic database involving the themes microglia, HPA axis and depression were used to meet the objectives.Results: Exposition to stressful events is considered a common factor in the mechanisms proposed to explain the depressive disorder. Stress can activate microglial cells, important immune components of the central nervous system (CNS). Moreover, another system involved in the physiological response to stressors is the hypothalamic-pituitary-adrenal (HPA) axis, the main stress response system responsible for the production of the glucocorticoid hormone (GC). Also, mediators released after microglial activation can stimulate the HPA axis, inducing production of GC. Likewise, high levels of GCs are also capable of activating microglia, generating a vicious cycle.Conclusion: Immune and neuroendocrine systems seems to work in a coordinated manner and that their dysregulation may be involved in the pathophysiology of depression since neuroinflammation and hypercortisolism are often observed in this disorder.

Restoring the oxidative balance in age-related diseases - An approach in glaucoma

As human life expectancy increases, age-related health issues including neurodegenerative diseases continue to rise. Regardless of genetic or environmental factors, many neurodegenerative conditions share common pathological mechanisms, such as oxidative stress, a hallmark of many age-related health burdens. In this review, we describe oxidative damage and mitochondrial dysfunction in glaucoma, an age-related neurodegenerative eye disease affecting 80 million people worldwide. We consider therapeutic approaches used to counteract oxidative stress in glaucoma, including untapped treatment options such as novel plant-derived antioxidant compounds that can reduce oxidative stress and prevent neuronal loss. We summarize the current pre-clinical models and clinical work exploring the therapeutic potential of a range of candidate plant-derived antioxidant compounds. Finally, we explore advances in drug delivery systems, particular those employing nanotechnology-based carriers which hold significant promise as a carrier for antioxidants to treat age-related disease, thus reviewing the key current state of all of the aspects required towards translation.

Gut Microbiome and Neuroinflammation in Hypertension

Hypertension is a worldwide problem with major impacts on health including morbidity and mortality, as well as consumption of health care resources. Nearly 50% of American adults have high blood pressure, and this rate is rising. Even with multiple antihypertensive drugs and aggressive lifestyle modifications, blood pressure is inadequately controlled in about 1 of 5 hypertensive individuals. This review highlights a hypothesis for hypertension that suggests alternative mechanisms for blood pressure elevation and maintenance. A better understanding of these mechanisms could open avenues for more successful treatments. The hypothesis accounts for recent understandings of the involvement of gut physiology, gut microbiota, and neuroinflammation in hypertension. It includes bidirectional communication between gut microbiota and gut epithelium in the gut-brain axis that is involved in regulation of autonomic nervous system activity and blood pressure control. Dysfunction of this gut-brain axis, including dysbiosis of gut microbiota, gut epithelial dysfunction, and deranged input to the brain, contributes to hypertension via inflammatory mediators, metabolites, bacteria in the circulation, afferent information alterations, etc resulting in neuroinflammation and unbalanced autonomic nervous system activity that elevates blood pressure. This in turn negatively affects gut function and its microbiota exacerbating the problem. We focus this review on the gut-brain axis hypothesis for hypertension and possible contribution to racial disparities in hypertension. A novel idea, that immunoglobulin A-coated bacteria originating in the gut with access to the brain could be involved in hypertension, is raised. Finally, minocycline, with its anti-inflammatory and antimicrobial properties, is evaluated as a potential antihypertensive drug acting on this axis.

Therapeutic promise of carotenoids as antioxidants and anti-inflammatory agents in neurodegenerative disorders

Neurodegenerative disorders (NDs) including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis have various disease-specific causal factors and pathological features. A very common characteristic of NDs is oxidative stress (OS), which takes place due to the elevated generation of reactive oxygen species during the progression of NDs. Furthermore, the pathological condition of NDs including an increased level of protein aggregates can further lead to chronic inflammation because of the microglial activation. Carotenoids (CTs) are naturally occurring pigments that play a significant role in averting brain disorders. More than 750 CTs are present in nature, and they are widely available in plants, microorganisms, and animals. CTs are accountable for the red, yellow, and orange pigments in several animals and plants, and these colors usually indicate various types of CTs. CTs exert various bioactive properties because of its characteristic structure, including anti-inflammatory and antioxidant properties. Due to the protective properties of CTs, levels of CTs in the human body have been markedly linked with the prevention and treatment of multiple diseases including NDs. In this review, we have summarized the relationship between OS, neuroinflammation, and NDs. In addition, we have also particularly focused on the antioxidants and anti-inflammatory properties of CTs in the management of NDs.

A Review of Pharmacology, Toxicity and Pharmacokinetics of 2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-Glucoside

Polygonum multiflorum Thunb. (He-shou-wu in Chinese), a Chinese botanical drug with a long history, is widely used to treat a variety of chronic diseases in clinic, and has been given the reputation of “rejuvenating and prolonging life” in many places. 2,3,4′,5-tetrahydroxystilbene-2-O-β-D-glucoside (TSG, C₂₀H₂₂O₉) is the main and unique active ingredient isolated from Polygonum multiflorum Thunb., which has extensive pharmacological activities. Modern pharmacological studies have confirmed that TSG exhibits significant activities in treating various diseases, including inflammatory diseases, neurodegenerative diseases, cardiovascular diseases, hepatic steatosis, osteoporosis, depression and diabetic nephropathy. Therefore, this review comprehensively summarizes the pharmacological and pharmacokinetic properties of TSG up to 2021 by searching the databases of Web of Science, PubMed, ScienceDirect and CNKI. According to the data, TSG shows remarkable anti-inflammation, antioxidation, neuroprotection, cardiovascular protection, hepatoprotection, anti-osteoporosis, enhancement of memory and anti-aging activities through regulating multiple molecular mechanisms, such as NF-κB, AMPK, PI3K-AKT, JNK, ROS-NO, Bcl-2/Bax/Caspase-3, ERK1/2, TGF-β/Smad, Nrf2, eNOS/NO and SIRT1. In addition, the toxicity and pharmacokinetics of TSG are also discussed in this review, which provided direction and basis for the further development and clinical application of TSG.

Nanotechnology-Abetted Astaxanthin Formulations in Multimodel Therapeutic and Biomedical Applications

Astaxanthin (AXT) is one of the most important fat-soluble carotenoids that have abundant and diverse therapeutic applications namely in liver disease, cardiovascular disease, cancer treatment, protection of the nervous system, protection of the skin and eyes against UV radiation, and boosting the immune system. However, due to its intrinsic reactivity, it is chemically unstable, and therefore, the design and production processes for this compound need to be precisely formulated. Nanoencapsulation is widely applied to protect AXT against degradation during digestion and storage, thus improving its physicochemical properties and therapeutic effects. Nanocarriers are delivery systems with many advantages─ease of surface modification, biocompatibility, and targeted drug delivery and release. This review discusses the technological advancement in nanocarriers for the delivery of AXT through the brain, eyes, and skin, with emphasis on the benefits, limitations, and efficiency in practice.

Enantioselective Synthesis and Pharmacological Evaluation of Aza-CGP37157–Lipoic Acid Hybrids for the Treatment of Alzheimer’s Disease

Hybrids based on an aza-analogue of CGP37157, a mitochondrial Na⁺/Ca²⁺ exchanger antagonist, and lipoic acid were obtained in order to combine in a single molecule the antioxidant and NRF2 induction properties of lipoic acid and the neuroprotective activity of CGP37157. The four possible enantiomers of the hybrid structure were synthesized by using as the key step a fully diastereoselective reduction induced by Ellman’s chiral auxiliary. After computational druggability studies that predicted good ADME profiles and blood–brain permeation for all compounds, the DPPH assay showed moderate oxidant scavenger capacity. Following a cytotoxicity evaluation that proved the compounds to be non-neurotoxic at the concentrations tested, they were assayed for NRF2 induction capacity and for anti-inflammatory properties and measured by their ability to inhibit nitrite production in the lipopolysaccharide-stimulated BV2 microglial cell model. Moreover, the compounds were studied for their neuroprotective effect in a model of oxidative stress achieved by treatment of SH-SY5Y neuroblastoma cells with the rotenone–oligomycin combination and also in a model of hyperphosphorylation induced by treatment with okadaic acid. The stereocenter configuration showed a critical influence in NRF2 induction properties, and also in the neuroprotection against oxidative stress experiment, leading to the identification of the compound with S and R configuration as an interesting hit with a good neuroprotective profile against oxidative stress and hyperphosphorylation, together with a relevant anti-neuroinflammatory activity. This interesting multitarget profile will be further characterized in future work.

Dopaminergic stimulation leads B-cell infiltration into the central nervous system upon autoimmunity

BACKGROUND

Recent evidence has shown dopamine as a major regulator of inflammation. Accordingly, dopaminergic regulation of immune cells plays an important role in the physiopathology of inflammatory disorders. Multiple sclerosis (MS) is an inflammatory disease involving a CD4⁺ T-cell-driven autoimmune response to central nervous system (CNS) derived antigens. Evidence from animal models has suggested that B cells play a fundamental role as antigen-presenting cells (APC) re-stimulating CD4⁺ T cells in the CNS as well as regulating T-cell response by mean of inflammatory or anti-inflammatory cytokines. Here, we addressed the role of the dopamine receptor D3 (DRD3), which displays the highest affinity for dopamine, in B cells in animal models of MS.

METHODS

Mice harbouring Drd3-deficient or Drd3-sufficient B cells were generated by bone marrow transplantation into recipient mice devoid of B cells. In these mice, we compared the development of experimental autoimmune encephalomyelitis (EAE) induced by immunization with a myelin oligodendrocyte glycoprotein (MOG)-derived peptide (pMOG), a model that leads to CNS-autoimmunity irrespective of the APC-function of B cells, or by immunization with full-length human MOG protein (huMOG), a model in which antigen-specific activated B cells display a fundamental APC-function in the CNS. APC-function was assessed in vitro by pulsing B cells with huMOG-coated beads and then co-culturing with MOG-specific T cells.

RESULTS

Our data show that the selective Drd3 deficiency in B cells abolishes the disease development in the huMOG-induced EAE model. Mechanistic analysis indicates that although DRD3-signalling did not affect the APC-function of B cells, DRD3 favours the CNS-tropism in a subset of pro-inflammatory B cells in the huMOG-induced EAE model, an effect that was associated with higher CXCR3 expression. Conversely, the results show that the selective Drd3 deficiency in B cells exacerbates the disease severity in the pMOG-induced EAE model. Further analysis shows that DRD3-stimulation increased the expression of the CNS-homing molecule CD49d in a B-cell subset with anti-inflammatory features, thus attenuating EAE manifestation in the pMOG-induced EAE model.

CONCLUSIONS

Our findings demonstrate that DRD3 in B cells exerts a dual role in CNS-autoimmunity, favouring CNS-tropism of pro-inflammatory B cells with APC-function and promoting CNS-homing of B cells with anti-inflammatory features. Thus, these results show DRD3-signalling in B cells as a critical regulator of CNS-autoimmunity.

Therapeutic Effects of Physical Exercise and the Mesenchymal Stem Cell Secretome by Modulating Neuroinflammatory Response in Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative, demyelinating, and chronic inflammatory disease characterized by central nervous system (CNS) lesions that lead to high levels of disability and severe physical and cognitive disturbances. Conventional therapies are not enough to control the neuroinflammatory process in MS and are not able to inhibit ongoing damage to the CNS. Thus, the secretome of mesenchymal stem cells (MSC-S) has been postulated as a potential therapy that could mitigate symptoms and disease progression. We considered that its combination with physical exercise (EX) could induce superior effects and increase the MSC-S effectiveness in this condition. Recent studies have revealed that both EX and MSC-S share similar mechanisms of action that mitigate auto-reactive T cell infiltration, regulate the local inflammatory response, modulate the proinflammatory profile of glial cells, and reduce neuronal damage. Clinical and experimental studies have reported that these treatments in an isolated way also improve myelination, regeneration, promote the release of neurotrophic factors, and increase the recruitment of endogenous stem cells. Together, these effects reduce disease progression and improve patient functionality. Despite these results, the combination of these methods has not yet been studied in MS. In this review, we focus on molecular elements and cellular responses induced by these treatments in a separate way, showing their beneficial effects in the control of symptoms and disease progression in MS, as well as indicating their contribution in clinical fields. In addition, we propose the combined use of EX and MSC-S as a strategy to boost their reparative and immunomodulatory effects in this condition, combining their benefits on synaptogenesis, neurogenesis, remyelination, and neuroinflammatory response. The findings here reported are based on the scientific evidence and our professional experience that will bring significant progress to regenerative medicine to deal with this condition.

New Insights into the Role of Cysteine Cathepsins in Neuroinflammation

Neuroinflammation, which is mediated by microglia and astrocytes, is associated with the progression of neurodegenerative diseases. Increasing evidence shows that activated microglia induce the expression and secretion of various lysosomal cathepsins, particularly during the early stage of neuroinflammation. This trigger signaling cascade that aggravate neurodegeneration. To date, most research on neuroinflammation has focused on the role of cysteine cathepsins, the largest cathepsin family. Cysteine cathepsins are primarily responsible for protein degradation in lysosomes; however, they also play a role in regulating a number of other important physiological and pathological processes. This review focuses on the functional roles of cysteine cathepsins in the central nervous system during neuroinflammation, with an emphasis on their roles in the polarization of microglia and neuroinflammation signaling, which in turn causes neuronal death and thus neurodegeneration.

Long-term corticosteroid-induced chronic glaucoma model produced by intracameral injection of dexamethasone-loaded PLGA microspheres

PURPOSE

To evaluate a new chronic glaucoma model produced by intracameral injection of dexamethasone-loaded poly lactic-co-glycolic acid microspheres (Dex-PLGA-Ms) over six months.

METHODS

Healthy rats received two injections (at baseline and Week 4) of Dex-PLGA-Ms into the anterior chamber of the right eye. Clinical signs and intraocular pressure (IOP) were weekly recorded. The structure of the retina and optic nerve was in vivo evaluated using optical coherence tomography (OCT) every two weeks and functionally using dark- and light-adapted electroretinography at 0-12-24 weeks. Histological studies were also performed.

RESULTS

IOP progressively increased up to hypertension (23.22 ± 3.63 mmHg) in both eyes but did so later in left eyes. OCT quantified a decrease in full-thickness retina posterior pole (R), retinal-nerve-fiber layer (RNFL), and ganglion-cell layer (GCL) thickness up to 24 weeks. Right eyes showed higher neuroretinal thickness loss up to week 8. RNFL experienced the highest percentage thickness loss at the inferior-superior axis, while in GCL the inner sectors of the horizontal axis (Nasal-Temporal) suffered the greatest decrease in thickness. Retinal ganglion cell, photoreceptor, and intermediate cell functionality decreased over time. Increased deposition of collagen IV was also found in zonular fibers and the ciliary body.

CONCLUSIONS

This work shows the usefulness of drug delivery systems, not to treat pathology but to induce it. Only two injections of Dex-PLGA-Ms in the anterior chamber of rat eyes were enough to progressively create ocular hypertension and subsequent functional and structural neuroretinal degeneration, at least over 6 months.

Baicalein ameliorates ischemic brain damage through suppressing proinflammatory microglia polarization via inhibiting the TLR4/NF-κB and STAT1 pathway

Microglial polarization mediated neuroinflammation plays an important role in the pathological process of stroke. The aim of this study is to determine whether baicalein indirectly ameliorates neuronal injury through modulating microglial polarization after stroke and if so, then by what mechanism. The effects of baicalein on microglial polarization were revealed through the middle cerebral artery occlusion mouse model (MCAO, n = 6), the lipopolysaccharide (LPS) + interferon-γ (IFN-γ) and oxygen-glucose deprivation (OGD) induced neuroinflammatory microglia model (BV2, n = 3), respectively. Mice were treated with baicalein (100 mg/kg, i.g.) after reperfusion, and followed by daily administrations for 3 days. Results showed that the infarct volumes at 3 d in vehicle and baicalein-treated MCAO mice were 91.18 ± 4.02% and 55.36 ± 4.10%. Baicalein improved sensorimotor functions (p < 0.01) after MCAO. Real-time PCR revealed that baicalein decreased proinflammatory markers expression (p < 0.05), while elevated the anti-inflammatory markers (p < 0.05) in vivo and in vitro. Both western blot and immunofluorescent staining further confirmed that baicalein reduced proinflammatory marker CD16 levels (p < 0.01) and enhanced anti-inflammatory marker CD206 or Arg-1 levels (p < 0.05). Notably, baicalein suppressed the release of proinflammatory cytokines (p < 0.05) and nitric oxide (NO, p < 0.001). Mechanistically, baicalein prevented increases in TLR4 protein levels (p < 0.001), the phosphorylation of IKBα and p65 (p < 0.01), and the nuclear translocation of NF-κB p65 (p < 0.05). The NF-κB inhibitor, BAY 11-7085, enhanced the inhibitory effect of baicalein on the proinflammatory microglial polarization. Baicalein also inhibited the phosphorylation of signal transducer and activator of transcription 1 (STAT1, p < 0.001). A microglia-neuron co-culture system revealed that baicalein driven neuroprotection against OGD induced neuronal damage through modulating microglial polarization (p < 0.05). Baicalein indirectly ameliorates neuronal injury after stroke by polarizing microglia toward the anti-inflammatory phenotype via inhibition of the TLR4/NF-κB pathway and down-regulation of phosphorylated STAT1, suggesting that baicalein might serve a potential therapy for stroke.