Microglia orchestrate neuroinflammation

SOCS modulates JAK-STAT pathway as a novel target to mediate the occurrence of neuroinflammation: Molecular details and treatment options

SOCS (Suppressor of Cytokine Signalling) proteins are intracellular negative regulators that primarily modulate and inhibit cytokine-mediated signal transduction, playing a crucial role in immune homeostasis and related inflammatory diseases. SOCS act as inhibitors by regulating the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, thereby intervening in the pathogenesis of inflammation and autoimmune diseases. Recent studies have also demonstrated their involvement in central immunity and neuroinflammation, showing a dual functionality. However, the specific mechanisms of SOCS in the central nervous system remain unclear. This review thoroughly elucidates the specific mechanisms linking the SOCS-JAK-STAT pathway with the inflammatory manifestations of neurodegenerative diseases. Based on this, it proposes the theory that SOCS proteins can regulate the JAK-STAT pathway and inhibit the occurrence of neuroinflammation. Additionally, this review explores in detail the current therapeutic landscape and potential of targeting SOCS in the brain via the JAK-STAT pathway for neuroinflammation, offering insights into potential targets for the treatment of neurodegenerative diseases.

B355252 Suppresses LPS-Induced Neuroinflammation in the Mouse Brain

B355252 is a small molecular compound known for potentiating neural growth factor and protecting against neuronal cell death induced by glutamate in vitro and cerebral ischemia in vivo. However, its other biological functions remain unclear. This study aims to investigate whether B355252 suppresses neuroinflammatory responses and cell death in the brain. C57BL/6j mice were intraperitoneally injected with a single dosage of lipopolysaccharide (LPS, 1 mg/kg) to induce inflammation. B355252 (1 mg/kg) intervention was started two days prior to the LPS injection. The animal behavioral changes were assessed pre- and post-LPS injections. The animal brains were harvested at 4 and 24 h post-LPS injection, and histological, biochemical, and cytokine array outcomes were examined. Results showed that B355252 improved LPS-induced behavioral deterioration, mitigated brain tissue damage, and suppressed the activation of microglial and astrocytes. Furthermore, B355252 reduced the protein levels of key pyroptotic markers TLR4, NLRP3, and caspase-1 and inhibited the LPS-induced increases in IL-1β, IL-18, and cytokines. In conclusion, B355252 demonstrates a potent anti-neuroinflammatory effect in vivo, suggesting that its potential therapeutic value warrants further investigation.

Enhanced innate responses in microglia derived from retinoblastoma patient-specific iPSCs

RB1 deficiency leads to retinoblastoma (Rb), the most prevalent intraocular malignancy. Tumor-associated macrophages (TAMs) are related to local inflammation disorder, particularly by increasing cytokines and immune escape. Microglia, the unique resident macrophages for retinal homeostasis, are the most important immune cells of Rb. However, whether RB1 deficiency affects microglial function remain unknown. In this study, microglia were successfully differentiated from Rb patient- derived human induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs), and then we investigated the function of RB1 in microglia by live imaging phagocytosis assay, immunofluorescence, RNA-seq, qRT-PCR, ELISA and retina organoids/microglia co-culturing. RB1 was abundantly expressed in microglia and predominantly located in the nucleus. We then examined the phagocytosis ability and secretion function of iMGs in vitro. We found that RB1 deficiency did not affect the expression of microglia-specific markers or the phagocytic abilities of these cells by live-imaging. Upon LPS stimulation, RB1-deficient microglia displayed enhanced innate immune responses, as evidenced by activated MAPK signaling pathway and elevated expression of IL-6 and TNF-α at both mRNA and protein levels, compared to wildtype microglia. Furthermore, retinal structure disruption was observed when retinal organoids were co-cultured with RB1-deficient microglia, highlighting the potential contribution of microglia to Rb development and potential therapeutic strategies for retinoblastoma.

Effects of Manganese and Iron, Alone or in Combination, on Apoptosis in BV2 Cells

The aim of study was to address the effects of manganese and iron, alone and in combination, on apoptosis of BV2 microglia cells, and to determine if combined exposure to these metals augments their individual toxicity. We used a murine microglial BV2 cell line. Cell cytotoxicity was analyzed by propidium iodide (PI) exclusion assay. Cell ROS production was analyzed by 2', 7'-dichlorofluorescin diacetate (DCFH-DA) probe staining. Pro-inflammatory cytokine production was monitored by ELISA. Cell apoptosis was analyzed by PE Annexin V/7-AAD staining. Mitochondrial membrane integrity was analyzed by flow cytometry. We used immunoblotting to analyze the effect of manganese, iron alone, or their combined exposure on the activation of caspase9, P53, Bax, and Bcl2 apoptosis signaling pathways. Caspase3 activity was determined using a Colorimetric. Manganese, iron, and their combined exposure for 24 h induced the activation of BV2 microglia cells and increased ROS production and the expression of the inflammatory cytokines, IL-1β and TNF-α. And we also found that the apoptosis rate increased, mitochondrial membrane potential decreased, apoptosis-related proteins caspase9, P53, Bax, and Bcl2 expression increased, and caspase3 activity increased. Furthermore, we found that combined manganese-iron cytotoxicity was lower than that induced by manganese exposure alone. Manganese, iron alone, or their combination exposure can induce apoptosis in glial cells. Iron can reduce the toxicity of manganese, and there is an antagonistic effect between manganese and iron.

Inflammation in obsessive-compulsive disorder: A literature review and hypothesis-based potential of transcranial photobiomodulation

Obsessive-compulsive disorder (OCD) is a disabling neuropsychiatric disorder that affects about 2%-3% of the global population. Despite the availability of several treatments, many patients with OCD do not respond adequately, highlighting the need for new therapeutic approaches. Recent studies have associated various inflammatory processes with the pathogenesis of OCD, including alterations in peripheral immune cells, alterations in cytokine levels, and neuroinflammation. These findings suggest that inflammation could be a promising target for intervention. Transcranial photobiomodulation (t-PBM) with near-infrared light is a noninvasive neuromodulation technique that has shown potential for several neuropsychiatric disorders. However, its efficacy in OCD remains to be fully explored. This study aimed to review the literature on inflammation in OCD, detailing associations with T-cell populations, monocytes, NLRP3 inflammasome components, microglial activation, and elevated proinflammatory cytokines such as TNF-α, CRP, IL-1β, and IL-6. We also examined the hypothesis-based potential of t-PBM in targeting these inflammatory pathways of OCD, focusing on mechanisms such as modulation of oxidative stress, regulation of immune cell function, reduction of proinflammatory cytokine levels, deactivation of neurotoxic microglia, and upregulation of BDNF gene expression. Our review suggests that t-PBM could be a promising, noninvasive intervention for OCD, with the potential to modulate underlying inflammatory processes. Future research should focus on randomized clinical trials to assess t-PBM's efficacy and optimal treatment parameters in OCD. Biomarker analyses and neuroimaging studies will be important in understanding the relationship between inflammatory modulation and OCD symptom improvement following t-PBM sessions.

LRRK2 G2019S and Parkinson's disease: insight from Neuroinflammation

The multiple hypothesis holds that the pathogenesis of Parkinson's disease (PD) requires many factors such as heredity, environment and ageing. Mutations in Leucine-rich repeat kinase 2 (LRRK2) are recognized the risk factors of PD, and closely related to sporadic and familial PD and can regulate a variety of cellular pathways and processes. An Increasing number of studies has shown that glial hyperactivation-mediated neuroinflammation participates in dopaminergic neuron degeneration and pathogenesis of PD. LRRK2 is essential to the regulaton of chronic inflammation, especially for the central nervous system. The review spotlights on the novel development of LRRK2 on microglia and astrocytes, and explore their potential therapeutic targets, in order to provide a new insights in PD. Key messages: What is already known on this topic The G2019S mutation of LRRK2 is now recognised as a pathogenic mutation in PD. Previous studies have focused on the relationship between neurons and LRRK2 G2019S. What this study adds Neuroinflammation mediated by LRRK2 G2019S of glial cells affects the progress and development of PD and attention must be paid to the role of LRRK2 G2019S in glial cells in PD. How this study might affect research, practice or policy Developing anti-inflammatory drugs from the perspective of LRRK2 G2019S of glial cells is a new direction for the treatment of PD.

From diabetic hyperglycemia to cerebrovascular Damage: A narrative review

Diabetes mellitus is a globally significant disease that can lead to systemic complications, particularly vascular damage, including cardiovascular and cerebrovascular diseases of relevance. The physiological changes resulting from the imbalance in blood glucose levels play a crucial role in initiating vascular endothelial damage. Elevated glucose levels can also penetrate the central nervous system, triggering diabetic encephalopathy characterized by oxidative damage to brain components and activation of alternative and neurotoxic pathways. This brain damage increases the risk of ischemic stroke, a leading cause of mortality worldwide and a major cause of disability among surviving patients. The aim of this review is to highlight important pathways related to hyperglycemic damage that extend to the brain and result in vascular dysfunction, ultimately leading to the occurrence of a stroke. Understanding how diabetes mellitus contributes to the development of ischemic stroke and its impact on patient outcomes is crucial for implementing therapeutic strategies that reduce the incidence of diabetes mellitus and its complications, ultimately decreasing morbidity and mortality associated with the disease.

LncRNA xist regulates sepsis associated neuroinflammation in the periventricular white matter of CLP rats by miR-122-5p/PKCη Axis

Background

Neuroinflammation is a common feature of many neurological diseases, and remains crucial for disease progression and prognosis. Activation of microglia and astrocytes can lead to neuroinflammation. However, little is known about the role of lncRNA xist and miR-122-5p in the pathogenesis of sepsis-associated neuroinflammation (SAN). This study aims to investigate the role of lncRNA xist and miR-122-5p in the pathogenesis of SAN.

Methods

Levels of miR-122-5p and proinflammatory mediators were detected in the cerebrospinal fluid (CSF) of patients with intracranial infection (ICI) by ELISA and qRT-PCR. miRNA expression in the periventricular white matter (PWM) in rats was analyzed by high-throughput sequencing. Levels of lncRNA xist, miR-122-5p and proinflammatory mediators in the PWM were measured using qRT-PCR and western blot. Bioinformatics analysis was used to predict the upstream and downstream of miR-122-5p. The interaction between miR-122-5p and its target protein was validated using luciferase reporter assay. BV2 and astrocytes were used to detect the expression of lncRNA xist, miR-122-5p.

Results

The level of miR-122-5p was significantly decreased in the CSF of ICI patients, while the expression of IL-1β and TNF-α were significantly upregulated. Furthermore, it was found that the expression of IL-1β and TNF-α were negatively correlated with the level of miR-122-5p. A high-throughput sequencing analysis showed that miR-122-5p expression was downregulated with 1.5-fold changes in the PWM of CLP rats compared with sham group. Bioinformatics analysis found that lncRNA xist and PKCη were the upstream and downstream target genes of miR-122-5p, respectively. The identified lncRNA xist and PKCη were significantly increased in the PWM of CLP rats. Overexpression of miR-122-5p or knockdown of lncRNA xist could significantly downregulate the level of PKCη and proinflammatory mediators from activated microglia and astrocytes. Meanwhile, in vitro investigation showed that silencing lncRNA xist or PKCη or enhancing the expression of miR-122-5p could obviously inhibit the release of proinflammatory mediators in activated BV2 cells and astrocytes.

Conclusion

LncRNA xist could regulate microglia and astrocytes activation in the PWM of CLP rats via miR-122-5p/PKCη axis, further mediating sepsis associated neuroinflammation.

Shikimic acid (SA) inhibits neuro-inflammation and exerts neuroprotective effects in an LPS-induced in vitro and in vivo model

Numerous studies have shown that neuroinflammation is involved in the process of neuronal damage in neurodegenerative diseases such as Parkinson's disease (PD), for example, and that inhibiting neuroinflammation help improve PD. Shikimic acid (SA) has anti-inflammatory, analgesic and antioxidant activities in numerous diseases. However, its effect and mechanism in PD remain unclear. In this experiment, we found that SA inhibits production of pro-inflammatory mediators and ROS in LPS-induced BV2 cells. Mechanistic studies demonstrated that SA suppresses neuro-inflammation by activating the AKT/Nrf2 pathway and inhibiting the NF-κB pathway. Further in vivo study, we confirmed that SA ameliorated the neurological damage and behavioral deficits caused by LPS injection in mice. In summary, these study highlighted the beneficial role of SA as a novel therapy with potential PD drug by targeting neuro-inflammation.

Neural System Impairment and Involved Microglia-Neuron Regulation of Broflanilide in Zebrafish Larvae

Broflanilide is widely used to control pests and has attracted attention due to its adverse effects on aquatic organisms. Our previous study showed that broflanilide has a negative impact on the central nervous system (CNS) at lethal dosages; however, its neural effects under practical situations and the underlying mechanisms remain unknown. To elucidate how broflanilide affects the CNS, we exposed zebrafish larvae to broflanilide at 16.9 and 88.0 μg/L (the environmentally relevant concentrations) for 120 h. Zebrafish locomotion was significantly disturbed at 88.0 μg/L, with a decreased moving distance and velocity accompanied by an inhibited neurotransmitter level. In vivo neuroimaging analysis indicated that the nerves of zebrafish larvae, including the axons, myelin sheaths, and neurons, were impaired. The number of neurons was significantly reduced after exposure, with an impaired morphological structure. These changes were accompanied by the abnormal transcription of genes involved in early CNS development. In addition, an increased total number of microglia and an elevated proportion of amoeboid microglia were observed after 88.0 μg/L broflanilide exposure, pointing out to an upstream role of microglia activation in mediating broflanilide neurotoxicity. Meanwhile, increased inflammatory cytokine levels and brain neutrophil numbers were observed, implicating significant inflammatory response and immune toxicity. Our findings indicate that broflanilide interferes with microglia-neuron regulation and induces neurodevelopmental disorders.

An Exosome-Based Therapeutic Strategy Targeting Neuroinflammation in Alzheimer's Disease with Berberine and Palmatine

Introduction

Neuroinflammation is one of the major pathogeneses in Alzheimer's disease (AD) and mainly involves abnormal inflammatory activation of microglia by multiple pathological stimuli. The treatment of AD remains a major challenge due to the multifactorial characterization of AD and the inefficient ability of therapeutic drugs to permeate through the blood‒brain barrier (BBB). Accordingly, drug combination treatment and drug carrier delivery have become important therapeutic tools for the treatment of multifactorial diseases, especially AD.

Methods

Inflammatory cytokine levels in microglia, including NO, TNF-α, IL-1β, IL-4, and IL-10, were detected. The Morris water maze and object location task were used to investigate the learning and memory functions of APP/PS1 mice in different treatment groups. The number of neurons and plasticity of synapses were evaluated by immunofluorescence double labelling. Additionally, the ratio of β-amyloid plaques and the number of activated microglia were evaluated by immunofluorescence staining. The concentrations of β-amyloid plaques and inflammatory factors in the hippocampus were determined by ELISA. Microglia-derived exosomes (Exos) were extracted and purified by size exclusion chromatography. The distribution of exosomes and drugs was investigated in vitro and in vivo.

Results

Compared to single drug interventions, the combination of Ber and Pal (Ber/Pal) modulated microglial inflammatory cytokine levels. Ber/Pal promoted the recovery of learning and memory impairment in APP/PS1 mice. Immunofluorescence staining indicated that Ber/Pal restored neurons, inhibited Aβ plaque formation and microglial activation, and regulated the secretion of inflammatory factors. Exos promoted the accumulation of drugs in cells and tissues and improved the targeting of drugs across the BBB.

Conclusion

Ber/Pal could offer a synergistic and more comprehensive therapeutic effect in AD. Additionally, the microglia-derived Exos-Ber/Pal delivery system promoted the targeting and permeation of drugs into the brain, suggesting a creative strategy for targeting AD therapy by regulating neuroinflammation in microglial cells.

The Signaling Pathway of the ADP Receptor P2Y12 in the Immune System: Recent Discoveries and New Challenges

P2Y12 is a G-protein-coupled receptor that is activated upon ADP binding. Considering its well-established role in platelet activation, blocking P2Y12 has been used as a therapeutic strategy for antiplatelet aggregation in cardiovascular disease patients. However, receptor studies have shown that P2Y12 is functionally expressed not only in platelets and the microglia but also in other cells of the immune system, such as in monocytes, dendritic cells, and T lymphocytes. As a result, studies were carried out investigating whether therapies targeting P2Y12 could also ameliorate inflammatory conditions, such as sepsis, rheumatoid arthritis, neuroinflammation, cancer, COVID-19, atherosclerosis, and diabetes-associated inflammation in animal models and human subjects. This review reports what is known about the expression of P2Y12 in the cells of the immune system and the effect of P2Y12 activation and/or inhibition in inflammatory conditions. Lastly, we will discuss the major problems and challenges in studying this receptor and provide insights on how they can be overcome.

PGRN deficiency exacerbates, whereas a brain penetrant PGRN derivative protects, GBA1 mutation-associated pathologies and diseases

Mutations in GBA1, encoding glucocerebrosidase (GCase), cause Gaucher disease (GD) and are also genetic risks in developing Parkinson's disease (PD). Currently, the approved therapies are only effective for directly treating visceral symptoms, but not for primary neuronopathic involvement in GD (nGD). Progranulin (PGRN), encoded by GRN, is a novel modifier of GCase, but the impact of PGRN in GBA1 mutation-associated pathologies in vivo remains unknown. Herein, Grn^-/- mice crossed into Gba^9v/9v mice, a Gba1 mutant line homozygous for the Gba1 D409V mutation, generating Grn^-/-Gba^9v/9v (PG9V) mice. PG9V mice exhibited neurobehavioral deficits, early onset, and more severe GD phenotypes compared to Grn^-/- and Gba^9v/9v mice. Moreover, PG9V mice also displayed PD-like phenotype. Mechanistic analysis revealed that PGRN deficiency caused severe neuroinflammation with microgliosis and astrogliosis, along with impaired autophagy associated with the Gba1 mutation. A PGRN-derived peptide, termed ND7, ameliorated the disease phenotype in GD patient fibroblasts ex vivo. Unexpectedly, ND7 penetrated the blood-brain barrier (BBB) and effectively ameliorated the nGD manifestations and PD pathology in Gba^9v/null and PG9V mice. Collectively, this study not only provides the first line of in vivo but also ex vivo evidence demonstrating the crucial role of PGRN in GBA1/Gba1 mutation-related pathologies, as well as a clinically relevant mouse model for mechanistic and potential therapeutics studies for nGD and PD. Importantly, a BBB penetrant PGRN-derived biologic was developed that may provide treatment for rare lysosomal storage diseases and common neurodegenerative disorders, particularly nGD and PD.