JAK2/STAT3 pathway regulates microglia polarization involved in hippocampal inflammatory damage due to acute paraquat exposure

Inactivation of cGAS signaling pathway mediated by TDP-43 deficiency protects microglia from hypoxia/reoxygenation induced injury

BACKGROUND

Microglia are damaged during cerebral ischemia-reperfusion (I/R). This study was performed to investigate the regulatory effect of tAR DNA-binding protein-43 (TDP-43) on microglia after cerebral I/R in vitro and in vivo.

METHOD

The hypoxia/reoxygenation (H/R) treated microglia and rats with middle cerebral artery occlusion surgery were constructed respectively. The TDP-43 expression in brain tissues and microglia of each group was evaluated by qPCR and western blotting methods. Cell viability and cell apoptosis were combined to evaluate the degree of cell injury. As for animal experiments, neurological score and infarct volume were obtained to evaluate neurological injury.

RESULTS

The levels of TDP-43 in the brain tissues of I/R group were higher than that in sham group. Both TDP-43 and Iba1, a typical microglia marker, were expressed in the brain tissues. TDP-43 was also elevated in microglia with H/R treatment. Inhibition of TDP-43 significantly down-regulated neurological deficit scores of rats after I/R surgery, and weakened the H/R treatment induced injury by promoting cell viability, inhibiting cell apoptosis, down-regulating IL-6 and iNOS levels, and up-regulating Arg-1 and IL-10 levels. Inactivation of cGAS pathway mediated by TDP-43 knockdown protects microglia from H/R treatment induced injury.

CONCLUSION

The highly expressed TDP-43 level is associated with cerebral I/R, and inhibition of TDP-43 protects microglia from H/R induced injury through cGAS pathway in vitro and in vivo.

CCR3 knockdown attenuates prolonged underwater operations-induced cognitive impairment via alleviating microglia-mediated neuroinflammation

Maintaining cognitive integrity is crucial during underwater operations, which can significantly impact work performance and risk severe accidents. However, the cognitive effects of underwater operations and their underlying mechanism remain elusive, posing great challenges to the medical protection of professionals concerned. Here, we found that a single underwater operation session affects cognition in a time-dependent model. Prolonged exposure elicits significant cognitive impairment and hippocampal dysfunction, accompanied by increased neuroinflammation. Furthermore, RNA sequencing (RNA-seq) analysis revealed the involvement of neuroinflammation and highlighted the critical role of CCR3. Knockdown of CCR3 significantly rescued cognitive impairment and hippocampal dysfunction and reversed the upregulation of pro-inflammatory cytokines, by switching the activated microglia from a pro-inflammatory to a neuroprotective phenotype. Taken together, these results highlighted the time-dependent effects of a single underwater operation session on cognitive function. Knocking down CCR3 can attenuate neuroinflammation by regulating polarization of activated microglia, thereby alleviating prolonged underwater operations-induced cognitive impairment.

Effect of Selenium nanoparticles on Paraquat-induced-neuroinflammation and oligodendocyte modulation: Implication of the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway

BACKGROUND

Paraquat (PQ), is an extensively used herbicide and is a well-established powerful neurotoxin. However, the mechanism underlying its neurotoxicity still needs further investigation.

AIM OF WORK

The study investigated the pathogenesis of PQ-induced neuroinflammation of the substantia nigra pars compacta (SNPC) and cerebellum and evaluated the potential effect of selenium nanoparticles (SeN) against such neurotoxicity.

METHODS

Thirty-six mice were randomly divided into three groups; Control group, PQ group: mice received PQ 10 mg/kg (i.p), and PQ + SeN group; mice received PQ in addition to oral SeN 0.1 mg/kg. All regimens were administered for 14 days. The mice's brains were processed for biochemical, molecular, histological, and immune-histochemical assessment.

RESULTS

SeN increased the SNPC and cerebellum antioxidants (reduced glutathione, glutathione peroxidase, and superoxide dismutase 1) while decreasing malondialdehyde concentration. Also, SeN increased the anti-inflammatory interleukin (IL)-10 and decreased the pro-inflammatory IL-1β and -6 along with improving the angiogenic nitric oxide and reducing caspase-1. Further, western blots of phosphorylated Janus kinase (JAK2)/signal transducer and activator of transcription3 (STAT3) proteins showed a significant decline. Those improving effects of SeN on SNPC, and cerebellum were supported by the significantly preserved dopaminergic and Purkinje neurons, the enhanced myelin fibers on Luxol fast blue staining, and the marked increase in Olig-2, Platelet-derived growth factor-alpha, and tyrosine hydroxylase immunoreactivity.

CONCLUSION

SeN could mitigate PQ-induced neurotoxicity via its antioxidant, anti-inflammatory, and antiapoptotic properties.

The effect and mechanism of palmar ginseng in type 2 diabetic cognitive impairment

Objective

To investigate the therapeutic effect of palmar ginseng on cognitive impairment in rats with type 2 diabetes, evaluate its neuroprotective effects, and explore its underlying mechanism.

Methods

A rat model of diabetic cognitive impairment (DCI) was established by feeding with homemade high-fat, high-sugar chow combined with intraperitoneal injection of streptozotocin (STZ). Rats were continually fed high-fat, high-sugar chow for 60 days after successful induction of the model. Palmar ginseng was administered via gavage. The Morris test was performed after 30 days of treatment. At the end of the test, blood samples were collected, and the activities of IL-6, IL-10, TNF-α, and IL-1β in rat serum. Pathological changes in hippocampal tissues were observed by Haematoxylin-eosin (HE) staining of the brain, activation of microglia in hippocampal tissues was detected by immunofluorescence, and the expression of PI3K/Akt/mTOR and JAK2/STAT3 proteins in the hippocampal tissues by Western blot.

Results

During the administration of palmar Ginseng, the body weight and blood glucose levels of DCI rats were measured weekly, with results showing that Palmar Ginseng effectively reduced blood glucose levels and body weight of DCI rats. Behavioural tests in the water maze indicated that palmar ginseng effectively improved the learning and memory ability of DCI rats. HE and immunofluorescence staining showed that palmar ginseng improved DCI in rats, ameliorated hippocampal neuronal damage, and improved microglial activation. ELISA showed that palmar ginseng significantly reduced the expression of pro-inflammatory factors in the serum of DCI rats. Increased expression of anti-inflammatory factors was observed, and Western blot analysis showed that Palmar Ginseng regulated PI3K/Akt/mTOR and JAK2/STAT3 protein expression, promoted the phosphorylation of PI3K/Akt/mTOR, and inhibited JAK2/STAT3 protein phosphorylation in rat hippocampal tissues as well as in BV2 cells.

Conclusions

Palmar ginseng may improve the onset and development of DCI by upregulating the phosphorylation of proteins in the PI3K/Akt/mTOR pathway.

Edaravone dexborneol promotes M2 microglia polarization against lipopolysaccharide-induced inflammation via suppressing TLR4/MyD88/NF-κB pathway

Edaravone dexborneol (ED) is a novel neuroprotective compound that consists of two active ingredients, edaravone and ( +)-borneol in a 4:1 ratio, which has been shown the anti-inflammatory properties in animal models of ischemic stroke, cerebral hemorrhage, and autoimmune encephalomyelitis. However, the effect of ED on the polarization of microglia in neuroinflammation has not been elucidated. This study was to investigate the effects of ED on the polarization of microglia induced by lipopolysaccharide (LPS) and potential mechanisms. BV-2 microglial cells were incubated with ED (100, 200, and 400 µM) for 2 h, followed by lipopolysaccharide (LPS, 1 µg/ml) for 12 h. The researchers used the Griess method, western blot, immunocytochemistry, and subcellular fractionation to assess the effects and potential mechanisms of ED on neuroinflammatory reactions. The expression of ROS and the activities of antioxidant enzymes (SOD, GPx, and CAT) in LPS-induced BV-2 cells were also measured using the DCFH-DA fluorescent probe and colorimetric methods, respectively. It was observed that ED significantly declined the levels of TLR4/NF-κB pathway-associated proteins (TLR4, MyD88, p65, p-p65, IκBα, p-IκBα, IKKβ, p-IKKβ) and therefore inhibited LPS-induced production of NO, IL-1β, and TNF-α. Moreover, ED markedly downregulated the M1 marker (iNOS) and upregulated the M2 marker (Arginase-1, Ym-1). In addition, ED also reduced ROS generation and enhanced GPx activity. ED induced the polarization of LPS-stimulated microglia from M1 to M2 against inflammation by negatively regulating the TLR4/MyD88/NF-κB signaling pathway. Additionally, ED performed antioxidative function by depleting the intracellular excessive ROS caused by LPS through the enhancement of the enzymatic activity of GPx. ED may be a potential agent to attenuate neuroinflammation via regulating the polarization of microglia.

The Phytochemical Agathisflavone Modulates miR146a and miR155 in Activated Microglia Involving STAT3 Signaling

MicroRNAs (miRs) act as important post-transcriptional regulators of gene expression in glial cells and have been shown to be involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). Here, we investigated the effects of agathisflavone, a biflavonoid purified from the leaves of Cenostigma pyramidale (Tul.), on modulating the expression of miRs and inflammatory mediators in activated microglia. C20 human microglia were exposed to oligomers of the β-amyloid peptide (Aβ, 500 nM) for 4 h or to lipopolysaccharide (LPS, 1 µg/mL) for 24 h and then treated or not with agathisflavone (1 µM) for 24 h. We observed that β-amyloid and LPS activated microglia to an inflammatory state, with increased expression of miR-146a, miR-155, IL1-β, IL-6, and NOS2. Treatment with agathisflavone resulted in a significant reduction in miR146a and miR-155 induced by LPS or Aβ, as well as inflammatory cytokines IL1-β, IL-6, and NOS2. In cells stimulated with Aβ, there was an increase in p-STAT3 expression that was reduced by agathisflavone treatment. These data identify a role for miRs in the anti-inflammatory effect of agathisflavone on microglia in models of neuroinflammation and AD.

Elucidating the mechanisms underlying astrocyte-microglia crosstalk in hippocampal neuroinflammation induced by acute diquat exposure

The transition from paraquat (PQ) to diquat (DQ), both organic dication herbicides, in China has led to significant increases in the number of acute DQ poisoning cases. Case studies have shown that acute DQ poisoning resulted in injury to the central nervous system (CNS), but the mechanism underlying the injury remains to be explored. The present study aimed to investigate how DQ influenced purinergic signaling between astrocytes and microglia and whether extracellular ATP (eATP) was involved in promoting neuroinflammation induced by acute DQ toxicity through the activation of the P2X4/NLRP3 signaling pathway. We constructed a rat model of acute DQ toxicity to observe the pathological changes in hippocampal tissues after DQ exposure and measure the expression levels of IL-1β and TNF-α in the hippocampal tissue. We also established an in vitro co-culture model of C6 astrocytes and BV-2 microglia using transwell chambers, measured the amount of eATP secreted into C6 astrocytes after DQ treatment, and assessed the inflammatory response and changes in the P2X4/NLRP3 signaling pathway in BV-2 microglia. The results showed that the neurons in the hippocampal tissue of rats exhibited loose arrangement, nuclear consolidation, and necrosis after DQ exposure, and IL-1β and TNF-α levels were signification higher in the hippocampal tissue after DQ exposure. DQ exposure to the co-cultured cells induced an increase in ATP secretion from C6 astrocytes as well as a significant increase of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. In contrast, pretreatment of C6 astrocytes with apyrase (an ATP hydrolase) resulted in a significant decrease of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. Furthermore, inhibition of P2X4 expression in BV-2 microglia by transfection with si-P2X4 effectively reversed the increase of NLRP3, IL-1β, and IL-18 in BV-2 microglia induced by DQ when co-cultured with C6 astrocytes. These results indicate that astrocytes can activate the P2X4/NLRP3 signaling pathway in microglia through the DQ-induced extracellular release of ATP to promote neuroinflammation in rat hippocampal tissue.

Therapeutic effects of anti-diabetic drugs on traumatic brain injury

AIMS

In this narrative review, we have analyzed and synthesized current studies relating to the effects of anti-diabetic drugs on traumatic brain injury (TBI) complications.

METHODS

Eligible studies were collected from Scopus, Google Scholar, PubMed, and Cochrane Library for clinical, in-vivo, and in-vitro studies published on the impact of anti-diabetic drugs on TBI.

RESULTS

Traumatic brain injury (TBI) is a serious brain disease that is caused by any type of trauma. The pathophysiology of TBI is not yet fully understood, though physical injury and inflammatory events have been implicated in TBI progression. Several signaling pathways are known to play pivotal roles in TBI injuries, including Nuclear factor erythroid 2-related factor 2 (Nrf2), High mobility group box 1 protein/Nuclear factor kappa B (HMGB1/NF-κB), Adiponectin, Mammalian Target of Rapamycin (mTOR), Toll-Like Receptor (TLR), Wnt/β-catenin, Janus Kinase/Signal Transducers and Activators of Transcription (JAK/STAT), Nod-like receptor protein3 (NLRP3) inflammasome, Phosphoglycerate kinase 1/Kelch-like ECH-associated protein 1 (PGK1/KEAP1)/Nrf2, and Mitogen-activated protein kinase (MAPK) . Recent studies suggest that oral anti-diabetic drugs such as biguanides, thiazolidinediones (TZDs), sulfonylureas (SUs), sodium-glucose cotransporter-2 inhibitors (SGLT2is), dipeptidyl peptidase-4 inhibitors (DPPIs), meglitinides, and alpha-glucosidase inhibitors (AGIs) could have beneficial effects in the management of TBI complications. These drugs may downregulate the inflammatory pathways and induce antioxidant signaling pathways, thus alleviating complications of TBI.

CONCLUSION

Based on this comprehensive literature review, antidiabetic medications might be considered in the TBI treatment protocol. However, evidence from clinical trials in patients with TBI is still warranted.

Microglia dynamic response and phenotype heterogeneity in neural regeneration following hypoxic-ischemic brain injury

Hypoxic-ischemic brain injury poses a significant threat to the neural niche within the central nervous system. In response to this pathological process, microglia, as innate immune cells in the central nervous system, undergo rapid morphological, molecular and functional changes. Here, we comprehensively review these dynamic changes in microglial response to hypoxic-ischemic brain injury under pathological conditions, including stroke, chronic intermittent hypoxia and neonatal hypoxic-ischemic brain injury. We focus on the regulation of signaling pathways under hypoxic-ischemic brain injury and further describe the process of microenvironment remodeling and neural tissue regeneration mediated by microglia after hypoxic-ischemic injury.

Tetramethylpyrazine promotes axonal remodeling and modulates microglial polarization via JAK2-STAT1/3 and GSK3-NFκB pathways in ischemic stroke

Ischemic stroke results in demyelination that underlies neurological disfunction. Promoting oligodendrogenesis will rescue the injured axons and accelerate remyelination after stroke. Microglia react to ischemia/hypoxia and polarize to M1/M2 phenotypes influencing myelin injury and repair. Tetramethylpyrazine (TMP) has neuroprotective effects in treating cerebrovascular disorders. This study aims to evaluate whether TMP promotes the renovation of damaged brain tissues especially on remyelination and modulates microglia phenotypes following ischemic stroke. Here magnetic resonance imaging (MRI)-diffusion tensor imaging (DTI) and histopathological evaluation are performed to characterize the process of demyelination and remyelination. Immunofluorescence staining is used to prove oligodendrogenesis and microglial polarization. Western blotting is conducted to examine interleukin (IL)-6, IL-10, transforming growth factor β (TGF-β) and Janus protein tyrosine kinase (JAK) 2-signal transducer and activator of transcription (STAT) 1/3-glycogen synthase kinase (GSK) 3-nuclear transcription factor κB (NFκB) signals. Results show TMP alleviates the injury of axons and myelin sheath, increases NG2+, Ki67+/NG2+, CNPase+, Ki67+/CNPase+, Iba1+/Arg-1+ cells and decreases Iba1+ and Iba1+/CD16+ cells in periinfarctions of rats. Particularly, TMP downregulates IL-6 and upregulates IL-10 and TGF-β expressions, besides, enhances JAK2-STAT3 and suppresses STAT1-GSK3-NFκB activation in middle cerebral artery occlusion (MCAo) rats. Then we demonstrate that TMP reverses M1/M2 phenotype via JAK2-STAT1/3 and GSK3-NFκB pathways in lipopolysaccharide (LPS) plus interferon-γ (IFN-γ)-stimulated BV2 microglia. Blocking JAK2 with AG490 counteracts TMP's facilitation on M2 polarization of microglia. This study warrants the promising therapy for stroke with TMP treatment.

Inhibition of BACE1 attenuates microglia-induced neuroinflammation after intracerebral hemorrhage by suppressing STAT3 activation

Hematoma-induced neuroinflammation is the cause of poor prognosis in intracerebral hemorrhage (ICH); therefore, promoting blood clearance and blocking overactivated inflammation are rational approaches for ICH treatment. β-site amyloid precursor protein (APP) lyase-1 (BACE1) is a key molecule regulating the microglial phenotype transition in neurodegenerative diseases. Therefore, the aim of this study was to investigate the role of BACE1 in microglial phagocytosis and inflammatory features in ICH. Here, we demonstrated the unique advantages of targeting BACE1 in microglia using an autologous blood model and primary microglia hemoglobin stimulation. When BACE1 was inhibited early in ICH, fewer residual hematomas remained, consistent with an increase in genetic features that favor phagocytosis and anti-inflammation. In addition, inhibition of BACE1 enhanced the secretion of anti-inflammatory cytokines and substantially reduced the expression of proinflammatory genes, which was regulated by signal transduction and phosphorylation of activator of transcription 3 (STAT3). Further pharmacological inhibition of STAT3 phosphorylation effectively blocked the proinflammatory and weak phagocytic phenotype of microglia due to BACE1 induction. In summary, BACE1 is the critical molecule regulating the inflammatory and phagocytic phenotypes of microglia after ICH, and targeted inhibition of the BACE1/STAT3 pathway is an important strategy for the future treatment of ICH-induced neurological injury.

Reactive astrocytes mediate TSPO overexpression in response to sustained CNTF exposure in the rat striatum

The 18 kDa translocator protein (TSPO) is a classical marker of neuroinflammation targeted for in vivo molecular imaging. Microglial cells were originally thought to be the only source of TSPO overexpression but astrocytes, neurons and endothelial cells can also up-regulate TSPO depending on the pathological context. This study aims to determine the cellular origin of TSPO overexpression in a simplified model of neuroinflammation and to identify the molecular pathways involved. This is essential to better interpret TSPO molecular imaging in preclinical and clinical settings. We used lentiviral vectors (LV) to overexpress the ciliary neurotrophic factor (CNTF) in the right striatum of 2-month-old Sprague Dawley rats. A LV encoding for β-Galactosidase (LV-LacZ) was used as control. One month later, TSPO expression was measured by single-photon emission computed tomography (SPECT) imaging using [¹²⁵I]CLINDE. The fluorescence-activated cell sorting to radioligand-treated tissue (FACS-RTT) method was used to quantify TSPO levels in acutely sorted astrocytes, microglia, neurons and endothelial cells. A second cohort was injected with LV-CNTF and a LV encoding suppressor of cytokine signaling 3 (SOCS3), to inhibit the JAK-STAT3 pathway specifically in astrocytes. GFAP and TSPO expressions were quantified by immunofluorescence. We measured a significant increase in TSPO signal in response to CNTF by SPECT imaging. Using FACS-RTT, we observed TSPO overexpression in reactive astrocytes (+ 153 ± 62%) but also in microglia (+ 2088 ± 500%) and neurons (+ 369 ± 117%), accompanied by an increase in TSPO binding sites per cell in those three cell populations. Endothelial cells did not contribute to TSPO signal increase. Importantly, LV-SOCS3 reduced CNTF-induced astrocyte reactivity and decreased global TSPO immunoreactivity (-71% ± 30%), suggesting that TSPO overexpression is primarily mediated by reactive astrocytes. Overall, this study reveals that CNTF induces TSPO in multiple cell types in the rat striatum, through the JAK2-STAT3 pathway in astrocytes, identifying this cell type as the primary mediator of CNTF effects neuroinflammatory processes. Our results highlight the difficulty to interpret TSPO imaging in term of cellular origin without addition cellular analysis by FACS-RTT or quantitative immunostainings. Consequently, TSPO should only be used as a global marker of neuroinflammation.

Effects of Natural Product-Derived Compounds on Inflammatory Pain via Regulation of Microglial Activation

Inflammatory pain is a type of pain caused by tissue damage associated with inflammation and is characterized by hypersensitivity to pain and neuroinflammation in the spinal cord. Neuroinflammation is significantly increased by various neurotransmitters and cytokines that are expressed in activated primary afferent neurons, and it plays a pivotal role in the development of inflammatory pain. The activation of microglia and elevated levels of pro-inflammatory cytokines are the hallmark features of neuroinflammation. During the development of neuroinflammation, various intracellular signaling pathways are activated or inhibited in microglia, leading to the regulation of inflammatory proteins and cytokines. Numerous attempts have been conducted to alleviate inflammatory pain by inhibiting microglial activation. Natural products and their compounds have gained attention as potential candidates for suppressing inflammatory pain due to verified safety through centuries of use. Many studies have also shown that natural product-derived compounds have the potential to suppress microglial activation and alleviate inflammatory pain. Herein, we review the literature on inflammatory mediators and intracellular signaling involved in microglial activation in inflammatory pain, as well as natural product-derived compounds that have been found to suppress microglial activation. This review suggests that natural product-derived compounds have the potential to alleviate inflammatory pain through the suppression of microglial activation.

Microglia Mediated Neuroinflammation in Parkinson’s Disease

Parkinson’s Disease (PD) is the second most common neurodegenerative disorder seen, especially in the elderly. Tremor, shaking, movement problems, and difficulty with balance and coordination are among the hallmarks, and dopaminergic neuronal loss in substantia nigra pars compacta of the brain and aggregation of intracellular protein α-synuclein are the pathological characterizations. Neuroinflammation has emerged as an involving mechanism at the initiation and development of PD. It is a complex network of interactions comprising immune and non-immune cells in addition to mediators of the immune response. Microglia, the resident macrophages in the CNS, take on the leading role in regulating neuroinflammation and maintaining homeostasis. Under normal physiological conditions, they exist as “homeostatic” but upon pathological stimuli, they switch to the “reactive state”. Pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes are used to classify microglial activity with each phenotype having its own markers and released mediators. When M1 microglia are persistent, they will contribute to various inflammatory diseases, including neurodegenerative diseases, such as PD. In this review, we focus on the role of microglia mediated neuroinflammation in PD and also signaling pathways, receptors, and mediators involved in the process, presenting the studies that associate microglia-mediated inflammation with PD. A better understanding of this complex network and interactions is important in seeking new therapies for PD and possibly other neurodegenerative diseases.

Schisandra chinensis Lignans Exert Antidepressant Effects by Promoting BV2 Microglia Polarization toward the M2 Phenotype through the Activation of the Cannabinoid Receptor Type-2-Signal Transducer and Activator of Transcription 6 Pathway

Based on the current results, they showed that Schisandra chinensis lignans (SCL) ameliorated depressive-like behaviors in chronic unpredictable mild stress (CUMS) mice, alleviated neuroinflammation, and improved neuronal injury. This study aimed to explore whether SCL exerted antidepressant effects through inhibiting neuroinflammation, in turn improving neuronal injury. In vitro studies revealed that SCL blocked lipopolysaccharide-increased BV2 microglial M1 but promoted the M2 phenotype. The BV2-N2a interaction model suggested that increasing the M2 phenotype of BV2 played neuroprotective effects. The current studies demonstrated that SCL up-regulated the expression of CUMS- and LPS-decreased cannabinoid receptor type-2 (CB2R) mRNA. In vitro studies showed that the transfection of BV2 with siCrn2 blocked the SCL-increased M2 phenotype via the inactivating signal transducer and activator of transcription 6 (STAT6) pathway, further decreasing the viability of N2a cells. Finally, the possible pharmacodynamic compounds, γ-schisandrin and schisantherin A, were indicated by AutoDuck analysis. Overall, our study showed that SCL promoted microglia polarization toward the M2 phenotype, in turn exerting neuroprotective effects by activating CB2R-STAT6 signaling further to play antidepressant roles.

Neuroinflammation in retinitis pigmentosa: Therapies targeting the innate immune system

Retinitis pigmentosa (RP) is an important cause of irreversible blindness worldwide and lacks effective treatment strategies. Although mutations are the primary cause of RP, research over the past decades has shown that neuroinflammation is an important cause of RP progression. Due to the abnormal activation of immunity, continuous sterile inflammation results in neuron loss and structural destruction. Therapies targeting inflammation have shown their potential to attenuate photoreceptor degeneration in preclinical models. Regardless of variations in genetic background, inflammatory modulation is emerging as an important role in the treatment of RP. We summarize the evidence for the role of inflammation in RP and mention therapeutic strategies where available, focusing on the modulation of innate immune signals, including TNFα signaling, TLR signaling, NLRP3 inflammasome activation, chemokine signaling and JAK/STAT signaling. In addition, we describe epigenetic regulation, the gut microbiome and herbal agents as prospective treatment strategies for RP in recent advances.

Microglial polarization in TBI: Signaling pathways and influencing pharmaceuticals

Traumatic brain injury (TBI) is a serious disease that threatens life and health of people. It poses a great economic burden on the healthcare system. Thus, seeking effective therapy to cure a patient with TBI is a matter of great urgency. Microglia are macrophages in the central nervous system (CNS) and play an important role in neuroinflammation. When TBI occurs, the human body environment changes dramatically and microglia polarize to one of two different phenotypes: M1 and M2. M1 microglia play a role in promoting the development of inflammation, while M2 microglia play a role in inhibiting inflammation. How to regulate the polarization direction of microglia is of great significance for the treatment of patients with TBI. The polarization of microglia involves many cellular signal transduction pathways, such as the TLR-4/NF-κB, JAK/STAT, HMGB1, MAPK, and PPAR-γ pathways. These provide a theoretical basis for us to seek therapeutic drugs for the patient with TBI. There are several drugs that target these pathways, including fingolimod, minocycline, Tak-242 and erythropoietin (EPO), and CSF-1. In this study, we will review signaling pathways involved in microglial polarization and medications that influence this process.

The expression and the tumor suppressor role of CLDN6 in colon cancer

As a member of the tight junction family, CLDN6 is a tumor suppressor in breast cancer, but its role in colon cancer is unknown. In this research, we aimed at revealing the function of CLDN6 in colon cancer. We found that colon cancer tissues lowly expressed CLDN6, and the expression of CLDN6 was negatively correlated with lymph node metastasis. Similarly, CLDN6 was lowly expressed in the colon cancer cell line SW1116, and overexpression of CLDN6 inhibited cell proliferation in vitro and in vivo. Consistently, the migration and invasion abilities of cells were significantly inhibited after CLDN6 overexpression. In addition, we demonstrated that CLDN6 may inhibit the migration and invasion abilities by activating the TYK2/STAT3 pathway. Therefore, our data indicated that CLDN6 acted as a tumor suppressor and had the potential to be regarded as a biomarker for the progression of colon cancer.