IL-35 promotes microglial M2 polarization in a rat model of diabetic neuropathic pain

Interleukin-35 alleviates neuropathic pain and induces an anti-inflammatory shift in spinal microglia in nerve-injured male mice

Immune cells are critical in promoting neuroinflammation and neuropathic pain and in facilitating pain resolution, depending on their inflammatory and immunoregulatory cytokine response. Interleukin (IL)-35, secreted by regulatory immune cells, is a member of the IL-12 family with a potent immunosuppressive function. In this study, we investigated the effects of IL-35 on pain behaviors, spinal microglia phenotype following peripheral nerve injury, and in vitro microglial cultures in male and female mice. Intrathecal recombinant IL-35 treatment alleviated mechanical pain hypersensitivity prominently in male mice, with only a modest effect in female mice after sciatic nerve chronic constriction injury (CCI). IL-35 treatment resulted in sex-specific microglial changes following CCI, reducing inflammatory microglial markers and upregulating anti-inflammatory markers in male mice. Spatial transcriptomic analysis revealed that IL-35 suppressed microglial complement activation in the superficial dorsal horn in male mice after CCI. Moreover, in vitro studies showed that IL-35 treatment of cultured inflammatory microglia mitigated their hypertrophied morphology, increased their cell motility, and decreased their phagocytic activity, indicating a phenotypic shift towards homeostatic microglia. Further, IL-35 altered microglial cytokines/chemokines in vitro, suppressing the release of IL-9 and monocyte-chemoattractant protein-1 and increasing IL-10 in the supernatant of male microglial cultures. Our findings indicate that treatment with IL-35 modulates spinal microglia and alleviates neuropathic pain in male mice, suggesting IL-35 as a potential sex-specific targeted immunomodulatory treatment for neuropathic pain.

Jinmaitong alleviates diabetic neuropathic pain by inhibiting JAK2/STAT3 signaling in microglia of diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Jinmaitong (JMT) is a prescription of Traditional Chinese Medicine that is composed of 12 crude drugs. It has been used in the treatment of diabetic neuropathic pain (DNP) for more than 30 years.

AIM OF STUDY

Microglia are thought to play an important role in neuropathic pain. This study aimed to evaluate the protective effect of JMT against DNP and to investigate the underlying mechanisms in which the microglia and JAK2/STAT3 signaling pathway were mainly involved.

MATERIALS AND METHODS

The chemical composition of JMT was analyzed using liquid chromatography tandem mass spectrometry. The diabetes model was constructed using 11 to 12-week-old male Zucker diabetic fatty (ZDF) rat (fa/fa). The model rats were divided into 5 groups and were given JMT at three dosages (11.6, 23.2, and 46.4 g/kg, respectively, calculated as the crude drug materials), JAK inhibitor AG490 (positive drug, 10 μg/day), and placebo (deionized water), respectively, for eight weeks (n = 6). Meanwhile, Zucker lean controls (fa/+) were given a placebo (n = 6). Body weight was tested weekly and blood glucose was monitored every 2 weeks. The mechanical allodynia and heat hyperalgesia were assessed using mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) tests. After treatment, the microglia activation marker Iba-1, CD11B, CD68, neuroinflammatory mediators, and mediators of the JAK2/STAT3 signaling pathway were compared between different groups. The mRNA and protein levels of target genes were assessed by quantitative real-time PCR and Western Blot, respectively.

RESULTS

We found that JMT significantly inhibited the overactivation of microglia in spinal cords, and suppressed neuroinflammation of DNP model rats, thereby ameliorating neurological dysfunction and injuries. Furthermore, these effects of JMT could be attributed to the inhibition of the JAK2/STAT3 signaling pathway.

CONCLUSIONS

Our findings suggested that JMT effectively ameliorated DNP by modulating microglia activation via inhibition of the JAK2/STAT3 signaling pathway. The present study provided a basis for further research on the therapeutic strategies of DNP.

Irisin alleviates CFA-induced inflammatory pain by modulating macrophage polarization and spinal glial cell activation

Although the potent anti-inflammatory effects of irisin have been documented in various inflammatory disorders, its efficacy against inflammatory pain remains unexplored. Herein, we examined the therapeutic effects of irisin in a mouse model of inflammatory pain induced by complete Freund's adjuvant (CFA). Mice were divided into three groups: normal control, CFA-injected (CFA), and CFA plus irisin-treated (CFA+Irisin). The irisin-treated group exhibited a gradual reduction in mechanical allodynia and thermal hyperalgesia when compared with the CFA group. Moreover, treatment with irisin significantly upregulated the expression of M2 macrophage markers (interleukin [IL]-4 and IL-10) and downregulated M1 macrophage markers (IL-1β, IL-6, and tumor necrosis factor-α) in the local paw tissue, dorsal root ganglion, and spinal cord tissue. However, there was no significant difference in the total number of F4/80+ macrophages in the paw tissue and dorsal root ganglion, indicating phenotypic exchange. Treatment with irisin also downregulated the expression of the glial cell activation-related markers Iba-1 and GFAP in the spinal cord tissue. To elucidate the underlying mechanisms, we detected the expression of Toll-like receptor 4 (TLR4), MyD88, and interferon regulatory factor 5 (IRF5) in paw tissues, dorsal root ganglion, and spinal tissues, revealing that irisin could downregulate the expression of these proteins. Irisin alleviated inflammatory pain by modulating local tissue inflammation and peripheral and central neuroinflammation and reducing glial cell activation and M2 macrophage polarization by modulating the TLR4-MyD88-IRF5 signaling pathway. Accordingly, irisin is a promising candidate for treating inflammatory pain in various diseases.

CD300LF+ microglia impede the neuroinflammation following traumatic brain injury by inhibiting STING pathway

INTRODUCTION

The diversity in microglial phenotypes and functions following traumatic brain injury (TBI) is poorly characterized. The aim of this study was to explore precise targets for improving the prognosis of TBI patients from a microglial perspective.

OBJECTIVES

To assess whether the prognosis of TBI can be improved by modulating microglia function.

RESULTS

In CD300LF-deficient mice, we observed an increase in glial cell proliferation, more extensive neuronal loss, and worsened neurological function post-TBI. Transcriptomic comparisons between CD300LF-positive and CD300LF-negative microglia illuminated that the neuroprotective role of CD300LF is principally mediated by the inhibition of the STING signaling pathway. In addition, this protective effect can be augmented using the STING pathway inhibitor C-176.

CONCLUSIONS

Our research indicates that CD300LF reduces neuroinflammation and promotes neurological recovery after TBI, and that microglia are integral to the protective effects of CD300LF in this context. In summary, our findings highlight CD300LF as a critical molecular regulator modulating the adverse actions of microglia following acute brain injury and propose a novel therapeutic approach to enhance outcomes for patients with TBI.

Obacunone Alleviates Inflammatory Pain by Promoting M2 Microglial Polarization and by Activating Nrf2/HO-1 Signaling Pathway

Background

Treating inflammatory pain (IP) continues to pose clinical challenge, because of the lack of effective pharmacological interventions. Microglial polarization serves as pivotal determinant in IP progress. Obacunone (OB), a low-molecular-weight compound with a diverse array of biological functions, having reported as an activator of nuclear factor E2-related factor 2 (Nrf2), exhibits anti-inflammatory property. However, it remains uncertain whether OB can alleviate IP by facilitating the transition of microglial polarization from the M1 to M2 state through modulating Nrf2/ heme oxygenase-1 (HO-1) pathway.

Methods

We induced an mice IP model by subcutaneously administering Complete Freund's Adjuvant (CFA) into the hind paw. Paw withdrawal latency (PWL) in seconds (s) and paw withdrawal frequency (PWF) were employed to evaluate the establishment of the IP model, while a caliper was used to measure the maximal dorsoventral thickness of the mice paw. Nerve injury was assessed by Hematoxylin-Eosin (HE) Staining. Western blot and got conducted for detection of M1/M2 microglial polarization markers, Nrf2 and HO-1 in spinal cord tissues respectively.

Results

In comparison to the control cohort, PWF, M1 phenotype marker iNOS, CD86, paw thickness increased significantly within CFA cohort, while PWL, M2 phenotype marker Arg-1, interleukin-10 (IL-10) decreased in the CFA group. In comparison to model cohort, OB treatment decreased PWF, paw thickness, M1 phenotype marker iNOS, CD86 significantly, while PWL, M2 phenotype marker Arg-1, IL-10, Nrf2, HO-1 increased significantly. The morphological injuries of sciatic nerve in CFA mice were obviously improved by OB treatment. OB inhibited the release of M1-related IL-1β, CXCL1 but promoted M2-related TGF-β, IL-10 in serum in CFA mice. The intervention of the Nrf2 inhibitor ML385 mitigated analgesic effect of OB.

Conclusion

We demonstrate that OB is able to attenuate inflammatory pain via promoting microglia polarization from M1 to M2 and enhancing Nrf2/HO-1 signal. OB treatment may be a potential alternative agent in the treatment of IP.

Tumor necrosis factor α-induced protein 8-like-2 controls microglia phenotype via metabolic reprogramming in BV2 microglial cells and responses to neuropathic pain

Microglial are major players in neuroinflammation that have recently emerged as potential therapeutic targets for neuropathic pain. Glucose metabolic programming has been linked to differential activation state and function in microglia. Tumor necrosis factor α-induced protein 8-like-2 (TNFAIP8L2) is an important component in regulating the anti-inflammatory response. However, the role of TNFAIP8L2 in microglia differential state during neuropathic pain and its interplay with glucose metabolic reprogramming in microglia has not yet been determined. Thus, we aimed to investigate the role of TNFAIP8L2 in the status of microglia in vitro and in vivo. BV2 microglial cells were treated with lipopolysaccharides plus interferon-gamma (LPS/IFNγ) or interleukin-4 (IL-4) to induce the two different phenotypes of microglia in vitro. In vivo experiments were conducted by chronic constriction injury of the sciatic nerve (CCI). We investigated whether TNFAIP8L2 regulates glucose metabolic programming in BV2 microglial cells. The data in vitro showed that TNFAIP8L2 lowers glycolysis and increases mitochondrial oxidative phosphorylation (OXPHOS) in inflammatory microglia. Blockade of glycolytic pathway abolished TNFAIP8L2-mediated differential activation of microglia. TNFAIP8L2 suppresses inflammatory microglial activation and promotes restorative microglial activation in BV2 microglial cells and in spinal cord microglia after neuropathic pain. Furthermore, TNFAIP8L2 controls differential activation of microglia and glucose metabolic reprogramming through the MAPK/mTOR/HIF-1α signaling axis. This study reveals that TNFAIP8L2 plays a critical role in neuropathic pain, providing important insights into glucose metabolic reprogramming and microglial phenotypic transition, which indicates that TNFAIP8L2 may be used as a potential drug target for the prevention of neuropathic pain.

How inflammation dictates diabetic peripheral neuropathy: An enlightening review

BACKGROUND

Diabetic peripheral neuropathy (DPN) constitutes a debilitating complication associated with diabetes. Although, the past decade has seen rapid developments in understanding the complex etiology of DPN, there are no approved therapies that can halt the development of DPN, or target the damaged nerve. Therefore, clarifying the pathogenesis of DPN and finding effective treatment are the crucial issues for the clinical management of DPN.

AIMS

This review is aiming to summary the current knowledge on the pathogenesis of DPN, especially the mechanism and application of inflammatory response.

METHODS

We systematically summarized the latest studies on the pathogenesis and therapeutic strategies of diabetic neuropathy in PubMed.

RESULTS

In this seminal review, the underappreciated role of immune activation in the progression of DPN is scrutinized. Novel insights into the inflammatory regulatory mechanisms of DPN have been unearthed, illuminating potential therapeutic strategies of notable clinical significance. Additionally, a nuanced examination of DPN's complex etiology, including aberrations in glycemic control and insulin signaling pathways, is presented. Crucially, an emphasis has been placed on translating these novel understandings into tangible clinical interventions to ameliorate patient outcomes.

CONCLUSIONS

This review is distinguished by synthesizing cutting-edge mechanisms linking inflammation to DPN and identifying innovative, inflammation-targeted therapeutic approaches.

Interleukin-4 from curcumin-activated OECs emerges as a central modulator for increasing M2 polarization of microglia/macrophage in OEC anti-inflammatory activity for functional repair of spinal cord injury

Microglia/macrophages are major contributors to neuroinflammation in the central nervous system (CNS) injury and exhibit either pro- or anti-inflammatory phenotypes in response to specific microenvironmental signals. Our latest in vivo and in vitro studies demonstrated that curcumin-treated olfactory ensheathing cells (aOECs) can effectively enhance neural survival and axonal outgrowth, and transplantation of aOECs improves the neurological outcome after spinal cord injury (SCI). The therapeutic effect is largely attributed to aOEC anti-inflammatory activity through the modulation of microglial polarization from the M1 to M2 phenotype. However, very little is known about what viable molecules from aOECs are actively responsible for the switch of M1 to M2 microglial phenotypes and the underlying mechanisms of microglial polarization. Herein, we show that Interleukin-4 (IL-4) plays a leading role in triggering the M1 to M2 microglial phenotype, appreciably decreasing the levels of M1 markers IL‑1β, IL‑6, tumour necrosis factor-alpha (TNF-α) and inducible nitric oxide synthase (iNOS) and elevating the levels of M2 markers Arg-1, TGF-β, IL-10, and CD206. Strikingly, blockade of IL-4 signaling by siRNA and a neutralizing antibody in aOEC medium reverses the transition of M1 to M2, and the activated microglia stimulated with the aOEC medium lacking IL-4 significantly decreases neuronal survival and neurite outgrowth. In addition, transplantation of aOECs improved the neurological function deficits after SCI in rats. More importantly, the crosstalk between JAK1/STAT1/3/6-targeted downstream signals and NF-κB/SOCS1/3 signaling predominantly orchestrates IL-4-modulated microglial polarization event. These results provide new insights into the molecular mechanisms of aOECs driving the M1-to-M2 shift of microglia and shed light on new therapies for SCI through the modulation of microglial polarization.

RNA interference-mediated silencing of DNA methyltransferase 1 attenuates neuropathic pain by accelerating microglia M2 polarization

Background

DNA methyltransferase 1 (DNMT1) exerts imperative functions in neuropathic pain (NP). This study explored the action of RNA interference-mediated DNMT1 silencing in NP by regulating microglial M2 polarization.

Methods

NP rat models were established using chronic constriction injury (CCI) and highly aggressive proliferating immortalized (HAPI) microglia were treated with lipopolysaccharide (LPS) to induce microglia M1 polarization, followed by treatment of DNMT1 siRNA or si-DNMT1/oe-DNMT1, respectively. The pain threshold of CCI rats was assessed by determining mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL). Levels of inflammatory factors (TNF-α/IL-1β/IL-6/IL-10) and DNMT1 in rat L4-L6 spinal cord samples and HAPI cells were measured using ELISA, RT-qPCR, and Western blot. iNOS and Arg-1 mRNA levels were measured via RT-qPCR. DNMT1, M1 marker (iNOS), and M2 marker (Arg-1) levels in microglia of CCI rats were detected by immunofluorescence. Percentages of M1 microglia phenotype (CD16) and M2 microglia phenotype (CD206) were detected by flow cytometry. The phosphorylation of PI3K/Akt pathway-related proteins was determined by Western blot.

Results

CCI rats exhibited diminished MWT and TWL values, increased pro-inflammatory cytokines, and decreased anti-inflammatory cytokine IL-10. Additionally, DNMT1 was upregulated in CCI rat microglia. DNMT1 siRNA alleviated CCI-induced NP and facilitated M2 polarization of microglia in CCI rats. DNMT1 knockdown inhibited LPS-induced M1 polarization of HAPI cells and promoted M2 polarization by blocking the PI3K/Akt pathway, but DNMT1 overexpression inhibited the M1-to-M2 polarization of microglia.

Conclusion

RNA interference-mediated DNMT1 silencing accelerates microglia M2 polarization by impeding the PI3K/Akt pathway, thereby alleviating CCI-induced NP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02860-6.

Photoreceptor Cells Constitutively Express IL-35 and Promote Ocular Immune Privilege

Interleukin-27 is constitutively secreted by microglia in the retina or brain, and upregulation of IL-27 during neuroinflammation suppresses encephalomyelitis and autoimmune uveitis. However, while IL-35 is structurally and functionally similar to IL-27, the intrinsic roles of IL-35 in CNS tissues are unknown. Thus, we generated IL-35/YFP-knock-in reporter mice (p35-KI) and demonstrated that photoreceptor neurons constitutively secrete IL-35, which might protect the retina from persistent low-grade inflammation that can impair photoreceptor functions. Furthermore, the p35-KI mouse, which is hemizygous at the il12a locus, develops more severe uveitis because of reduced IL-35 expression. Interestingly, onset and exacerbation of uveitis in p35-KI mice caused by extravasation of proinflammatory Th1/Th17 lymphocytes into the retina were preceded by a dramatic decrease of IL-35, attributable to massive death of photoreceptor cells. Thus, while inflammation-induced death of photoreceptors and loss of protective effects of IL-35 exacerbated uveitis, our data also suggest that constitutive production of IL-35 in the retina might have housekeeping functions that promote sterilization immunity in the neuroretina and maintain ocular immune privilege.

The Molecular Role of IL-35 in Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and a common cause of cancer-related death. Better understanding of the molecular mechanisms, pathogenesis, and treatment of NSCLC can help improve patient outcomes. Significant progress has been made in the treatment of NSCLC, and immunotherapy can prolong patient survival. However, the overall cure and survival rates are low, especially in patients with advanced metastases. Interleukin-35 (IL-35), an immunosuppressive factor, is associated with the onset and prognosis of various cancers. Studies have shown that IL-35 expression is elevated in NSCLC, and it is closely related to the progression and prognosis of NSCLC. However, there are few studies on the mechanism of IL-35 in NSCLC. This study discusses the role of IL-35 and its downstream signaling pathways in the pathogenesis of NSCLC and provides new insights into its therapeutic potential.

DKK3 ameliorates neuropathic pain via inhibiting ASK-1/JNK/p-38-mediated microglia polarization and neuroinflammation

BACKGROUND

Neuropathic pain is a common and severely disabling state that affects millions of people worldwide. Microglial activation in the spinal cord plays a critical role in the pathogenesis of neuropathic pain. However, the mechanisms underlying spinal microglial activation during neuropathic pain remain incompletely understood. Here, we investigated the role of Dickkopf (DKK) 3 and its interplay with microglial activation in the spinal cord in neuropathic pain.

METHODS

In this study, we investigated the effects of intrathecal injection of recombinant DKK3 (rDKK3) on mechanical allodynia and microglial activation in the spinal cord after spared nerve injury (SNI) in rats by western blot (WB), immunofluorescence (IF), quantitative polymerase chain reaction (qPCR), and enzyme-linked immunosorbent assay (ELISA).

RESULTS

We found that SNI induced a significant decrease in the levels of DKK3, Kremen-1 and Dishevelled-1 (DVL-1) and up-regulated the expression of phosphorylated apoptosis signal-regulating kinase 1 (p-ASK1), phosphorylated c-JUN N-terminal kinase (p-JNK), phosphorylated p38 (p-p38) in the spinal cord. Moreover, our results showed that exogenous intrathecal administration of rDKK3 inhibited expression of p-ASK1, p-JNK, p-p38, promoted the transformation of microglia from M1 type to M2 type, and decreased the production of pro-inflammatory cytokines compared to the rats of SNI + Vehicle. However, these effects were reversed by intrathecal administration of Kremen-1 siRNA or Dishevelled-1 (DVL-1) siRNA.

CONCLUSIONS

These results suggest that DKK3 ameliorates neuropathic pain via inhibiting ASK-1/JNK/p-38-mediated microglia polarization and neuroinflammation, at least partly, by the Kremen-1 and DVL-1 pathways.

Interleukin-35 exhibits protective effects in a rat model of hypoxic-ischemic encephalopathy through the inhibition of microglia-mediated inflammation

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) brain damage is related to inflammatory responses and oxidative stress. Interleukin (IL)-35 is an antioxidant and anti-inflammatory cytokine. Thus, the effect of IL-35 treatment on neonatal rats with hypoxic-ischemic brain injury was investigated.

METHODS

A total of 96 7-day-old Sprague Dawley rats were randomly divided into three groups: sham group, HIE group, and IL-35 group. After left common carotid occlusion and 2.5 h hypoxia (HI injury), IL-35 (20 µg/g) was intraperitoneally (i.p.) administered to the pups. In vitro, BV2 cells were treated with or without IL-35 6 h before oxygen-glucose deprivation (OGD) insult and the microglia culture medium (MCM) was co-cultured with b.End3 cerebral vascular endothelial cells. Microglial polarization and activation were assessed by real-time quantitative polymerase chain reaction (RT-qPCR), Western blot, and enzyme-linked immunosorbent assay (ELISA). Endothelial cell dysfunction was measured by cell counting kit-8 and Western blot assays.

RESULTS

Administration of IL-35 alleviated neurological deficiencies, decreased brain edema, ameliorated cerebral infarction, and limited M1 microglial polarization in HI-injured pups. Meanwhile, IL-35 decreased pro-inflammatory cytokines, tumor necrosis factor-α, IL-1β, and reactive oxygen species generation in OGD-induced bEnd.3 cells. Furthermore, IL-35 treatment could reverse the vascular endothelial cell injury induced by microglial polarization. Finally, IL-35 markedly suppressed the activation of hypoxia-inducible factor-1α (HIF-1α) and the nuclear factor-κB (NF-κB) signaling pathway in vivo and in vitro.

CONCLUSIONS

IL-35 relieved hypoxic-ischemic-induced brain injury and inhibited the inflammatory response by suppressing microglial polarization and activation. These results suggest that IL-35 might have potential applications for the treatment of HIE.

Interleukin-35 from Interleukin-4-Stimulated Macrophages Alleviates Oxygen Glucose Deprivation/Re-oxygenation-Induced Neuronal Cell Death via the Wnt/β-Catenin Signaling Pathway

Currently, brain stroke is one of the leading causes of death and disabilities. It results in depletion of oxygen and glucose in certain areas of the brain, leading to neuronal death. Re-oxygenation has been proven to attenuate neuronal damage; however, sudden oxygen supply may also cause oxidative stress and subsequent inflammation. Hence, therapies to suppress re-oxygenation-induced oxidative damage are urgently needed. Interleukin (IL)-35, an immunomodulator secreted by regulatory T cells and regulatory B cells, is proven to be a strong immune-repressive cytokine. Here, we investigated the potential role of IL-35 in a disease model of oxygen glucose deprivation/re-oxygenation (OGD/R) and found that M2 macrophage-derived IL-35 significantly alleviated inflammatory response induced by oxidative stress. Our results also showed that IL-35 treatment decreased OGD/R-induced neuronal cell death and inflammatory response. Additionally, we demonstrated that IL-35 suppresses inflammatory response via the Wnt/β-catenin signaling pathway. Hence, our findings indicate that IL-35 therapy has great potential in the treatment of OGD/R-induced oxidative damage and related inflammatory diseases.

P2X7 receptor induces microglia polarization to the M1 phenotype in cancer-induced bone pain rat models

Background

The transition from pro-inflammatory M1 phenotype to anti-inflammatory M2 phenotype presents a novel therapeutic strategy for chronic pain.

Objective

We investigated the role of microglia polarization in cancer-induced bone pain (CIBP), as well as the role of the P2X7 receptor in modulating M1 to M2 polarization.

Methods

Walker-256 breast cancer cells were administered into tibias of female rats to induce bone cancer–associated cancer.

Results

During bone cancer development, the P2X7 receptor and M1 microglia markers were upregulated. In contrast, inhibition of the P2X7 receptor by BBG, a blood-brain barrier-permeable P2X7R-specific antagonist, alleviated the pain and promoted microglia polarization toward the M2 phenotype, while suppressing the M1 phenotype in vivo and in vitro.

Conclusion

P2X7 receptor-mediated spinal microglia polarization is involved in alleviation of CIBP. Therefore, P2X7R is a potential option for CIBP treatment.

IL-35 promotes EMT through STAT3 activation and induces MET by promoting M2 macrophage polarization in HCC

The tumor microenvironment and interplay with cancer cells could promote tumor growth and metastasis. Here we report that polarization state of macrophages could affect epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET). IL-35 level secreted by M1 macrophage was significantly higher than M2 macrophage and it facilitated EMT process through activation of STAT3 in hepatocellular carcinoma cells. Interestingly, IL-35 could not directly promote MET, but it could indirectly induce MET of HCC cells through M2 macrophage polarization. These results indicated the level of IL-35 in tumor microenvironment may fluctuate at different stages of oncogenesis to regulate epithelial plasticity of HCC and provide potential therapeutic targets for tumor metastasis.

Dihydromyricetin attenuates neuropathic pain via enhancing the transition from M1 to M2 phenotype polarization by potentially elevating ALDH2 activity in vitro and vivo

Background

Treatment for neuropathic pain as a refractory disease remains unsatisfactory and represents a significant clinical challenge. A highly effective drug is thus urgently needed for neuropathic pain treatment. Dihydromyricetin (DMY) is a flavonoid with a wide range of biological activities. The purpose of this research is to explore the effects of DMY on neuropathic pain and the underlying mechanism of its effect.

Methods

The effect of DMY was investigated in BV-2 cells and lipopolysaccharide (LPS)-induced BV-2 cells. A neuropathic pain model was established via spared nerve injury (SNI) surgery in mice, and the protein expression level was detected via Western blot assay. The percent of M1 and M2 phenotype polarization cells were detected via flow cytometry assay. Immunochemical staining assay was also performed to measure the marker levels of the M1 and M2 phenotype polarization cells and aldehyde dehydrogenase 2 (ALDH2) level, and mechanical pain sensitivity was evaluated via measurement of the mechanical withdrawal threshold.

Results

We found that DMY promoted the transition from M1 to M2 polarization and upregulated the ALDH2 level in vitro and vitro. ALDA-1, an ALDH2 agonist, promoted the switching from M1 to M2 polarization in vivo and vitro. DMY alleviated pain hypersensitivity induced by SNI via enhancing M2 phenotype polarization by elevating ALDH2 activity in mice. After DMY- or ALDA-1-microglia were injected into SNI-induced pain hypersensitive mice, the mechanical withdrawal threshold was increased significantly when compared with the SNI group.

Conclusions

Our data demonstrated that DMY alleviated neuropathic pain via enhancing the polarization transition from the M1 to M2 phenotype by potentially elevating ALDH2 activity in vitro and vivo. DMY- or ALDA-1-microglia may have alleviative effects on neuropathic pain. The findings herein provide a promising avenue for neuropathic pain treatment, suggesting a new target, ALDH2, in the treatment of neuropathic pain.

Protective Effects of Thalidomide on High-Glucose-Induced Podocyte Injury through In Vitro Modulation of Macrophage M1/M2 Differentiation

Objective. It has been shown that podocyte injury represents an important pathological basis that contributes to proteinuria and eventually leads to kidney failure. High glucose (HG) activates macrophage polarization, further exacerbating HG-induced podocyte injury. Our previous study on diabetic nephropathy rats indicated that thalidomide (Tha) has renoprotective properties. The present study explored the effects of Tha on mRNA and protein expressions of inducible nitric oxide synthase (iNOS), tumor necrosis factor- (TNF-) α, mannose receptor (CD206), and arginase- (Arg-) 1 in HG-activated macrophages. iNOS and TNF-α are established as markers of classically activated macrophage (M1). CD206 and Arg-1 are regarded as markers of alternatively activated macrophages (M2). During the experiment, the supernatants of (HG)-treated and (Tha)-treated macrophages, designated as (HG) MS and (Tha) MS, were simultaneously collected and processed. TNF-α and interleukin- (IL-) 1β levels as well as protein expressions of nephrin and podocin in HG, (HG) MS, and (Tha) MS-cultured podocytes were evaluated. The results showed that compared to the 11.1 mM normal glucose (NG), the 33.3 mM HG-cultured RAW 264.7 cells exhibited upregulated iNOS and TNF-α mRNAs and protein expressions, and downregulated CD206 and Arg-1 expressions significantly (p < 0.05). Tha 200 μg/ml suppressed iNOS and TNF-α, and promoted CD206 and Arg-1 expressions significantly compared to the HG group (p < 0.05). Furthermore, (HG) MS-treated podocytes showed an increase in TNF-α and IL-1β levels and a downregulation in nephrin and podocin expression significantly compared to NG-treated and HG-treated podocytes (p < 0.05). The (Tha 200 μg/ml) MS group exhibited a decrease in TNF-α and IL-1β level, and an upregulation in nephrin and podocin expressions significantly compared to the (HG) MS group (p < 0.05). Our research confirmed that HG-activated macrophage differentiation aggravates HG-induced podocyte injury in vitro and the protective effects of Tha might be related to its actions on TNF-α and IL-1β levels via its modulation on M1/M2 differentiation.

Novel Analgesics with Peripheral Targets

A limited number of peripheral targets generate pain. Inflammatory mediators can sensitize these. The review addresses targets acting exclusively or predominantly on sensory neurons, mediators involved in inflammation targeting sensory neurons, and mediators involved in a more general inflammatory process, of which an analgesic effect secondary to an anti-inflammatory effect can be expected. Different approaches to address these systems are discussed, including scavenging proinflammatory mediators, applying anti-inflammatory mediators, and inhibiting proinflammatory or facilitating anti-inflammatory receptors. New approaches are contrasted to established ones; the current stage of progress is mentioned, in particular considering whether there is data from a molecular and cellular level, from animals, or from human trials, including an early stage after a market release. An overview of publication activity is presented, considering a IuPhar/BPS-curated list of targets with restriction to pain-related publications, which was also used to identify topics.