Fatty acid binding protein 5 inhibition attenuates pronociceptive cytokine/chemokine expression and suppresses osteoarthritis pain: A comparative human and rat study.

OBJECTIVE: Osteoarthritis (OA) is often accompanied by debilitating pain that is refractory to available analgesics due in part to the complexity of signaling molecules that drive OA pain and our inability to target these in parallel. Fatty acid binding protein 5 (FABP5) is a lipid chaperone that regulates inflammatory pain; however, its contribution to OA pain has not been characterized. DESIGN: This combined clinical and pre-clinical study utilized synovial tissues obtained from subjects with end-stage OA and rats with monoiodoacetate-induced OA. Cytokine and chemokine release from human synovia incubated with a selective FABP5 inhibitor was profiled with cytokine arrays and ELISA. Immunohistochemical analyses were conducted for FABP5 in human and rat synovium. The efficacy of FABP5 inhibitors on pain was assessed in OA rats using incapacitance as an outcome. RNA-seq was then performed to characterize the transcriptomic landscape of synovial gene expression in OA rats treated with FABP5 inhibitor or vehicle. RESULTS: FABP5 was expressed in human synovium and FABP5 inhibition reduced the secretion of pronociceptive cytokines (interleukin-6 [IL6], IL8) and chemokines (CCL2, CXCL1). In rats, FABP5 was upregulated in the OA synovium and its inhibition alleviated incapacitance. The transcriptome of the rat OA synovium exhibited >6000 differentially expressed genes, including the upregulation of numerous pronociceptive cytokines and chemokines. FABP5 inhibition blunted the upregulation of the majority of these pronociceptive mediators. CONCLUSIONS: FABP5 is expressed in the OA synovium and its inhibition suppresses pronociceptive signaling and pain, indicating that FABP5 inhibitors may constitute a novel class of analgesics to treat OA.

Pathogenic mechanisms of human immunodeficiency virus (HIV)-associated pain.

Chronic pain is a prevalent neurological complication among individuals living with human immunodeficiency virus (PLHIV) in the post-combination antiretroviral therapy (cART) era. These individuals experience malfunction in various cellular and molecular pathways involved in pain transmission and modulation, including the neuropathology of the peripheral sensory neurons and neurodegeneration and neuroinflammation in the spinal dorsal horn. However, the underlying etiologies and mechanisms leading to pain pathogenesis are complex and not fully understood. In this review, we aim to summarize recent progress in this field. Specifically, we will begin by examining neuropathology in the pain pathways identified in PLHIV and discussing potential causes, including those directly related to HIV-1 infection and comorbidities, such as antiretroviral drug use. We will also explore findings from animal models that may provide insights into the molecular and cellular processes contributing to neuropathology and chronic pain associated with HIV infection. Emerging evidence suggests that viral proteins and/or antiretroviral drugs trigger a complex pathological cascade involving neurons, glia, and potentially non-neural cells, and that interactions between these cells play a critical role in the pathogenesis of HIV-associated pain.

Development of opioid-induced hyperalgesia depends on reactive astrocytes controlled by Wnt5a signaling.

Opioids are the frontline analgesics for managing various types of pain. Paradoxically, repeated use of opioid analgesics may cause an exacerbated pain state known as opioid-induced hyperalgesia (OIH), which significantly contributes to dose escalation and consequently opioid overdose. Neuronal malplasticity in pain circuits has been the predominant proposed mechanism of OIH expression. Although glial cells are known to become reactive in OIH animal models, their biological contribution to OIH remains to be defined and their activation mechanism remains to be elucidated. Here, we show that reactive astrocytes (a.k.a. astrogliosis) are critical for OIH development in both male and female mice. Genetic reduction of astrogliosis inhibited the expression of OIH and morphine-induced neural circuit polarization (NCP) in the spinal dorsal horn (SDH). We found that Wnt5a is a neuron-to-astrocyte signal that is required for morphine-induced astrogliosis. Conditional knock-out of Wnt5a in neurons or its co-receptor ROR2 in astrocytes blocked not only morphine-induced astrogliosis but also OIH and NCP. Furthermore, we showed that the Wnt5a-ROR2 signaling-dependent astrogliosis contributes to OIH via inflammasome-regulated IL-1ß. Our results reveal an important role of morphine-induced astrogliosis in OIH pathogenesis and elucidate a neuron-to-astrocyte intercellular Wnt signaling pathway that controls the astrogliosis.

A neuron-to-astrocyte Wnt5a signal governs astrogliosis during HIV-associated pain pathogenesis.

Chronic pain is the most common neurological disorder of HIV patients. Multiple neuropathologies were identified in the pain pathway. Among them is the prominent astrocytic reaction (also know an astrogliosis). However, the pathogenic role and mechanism of the astrogliosis are unclear. Here, we show that the astrogliosis is crucial for the pain development induced by a key neurotoxic HIV protein gp120 and that a neuron-to-astrocyte Wnt5a signal controls the astrogliosis. Ablation of astrogliosis blocked the development of gp120-induced mechanical hyperalgesia, and concomitantly the expression of neural circuit polarization in the spinal dorsal horn. We demonstrated that conditional knockout of either Wnt5a in neurons or its receptor ROR2 in astrocytes abolished not only gp120-induced astrogliosis but also hyperalgesia and neural circuit polarization. Furthermore, we found that the astrogliosis promoted expression of hyperalgesia and NCP via IL-1ß regulated by a Wnt5a-ROR2-MMP2 axis. Our results shed light on the role and mechanism of astrogliosis in the pathogenesis of HIV-associated pain.

Microglia Mediate HIV-1 gp120-Induced Synaptic Degeneration in Spinal Pain Neural Circuits.

HIV-1 infection of the nervous system causes various neurological diseases, and synaptic degeneration is likely a critical step in the neuropathogenesis. Our prior studies revealed a significant decrease of synaptic protein, specifically in the spinal dorsal horn of patients with HIV-1 in whom pain developed, suggesting a potential contribution of synaptic degeneration to the pathogenesis of HIV-associated pain. However, the mechanism by which HIV-1 causes the spinal synaptic degeneration is unclear. Here, we identified a critical role of microglia in the synaptic degeneration. In primary cortical cultures (day in vitro 14) and spinal cords of 3- to 5-month-old mice (both sexes), microglial ablation inhibited gp120-induced synapse decrease. Fractalkine (FKN), a microglia activation chemokine specifically expressed in neurons, was upregulated by gp120, and knockout of the FKN receptor CX3CR1, which is predominantly expressed in microglia, protected synapses from gp120-induced toxicity. These results indicate that the neuron-to-microglia intercellular FKN/CX3CR1 signaling plays a role in gp120-induced synaptic degeneration. To elucidate the mechanism controlling this intercellular signaling, we tested the role of the Wnt/ß-catenin pathway in regulating FKN expression. Inhibition of Wnt/ß-catenin signaling blocked both gp120-induced FKN upregulation and synaptic degeneration, and gp120 stimulated Wnt/ß-catenin-regulated FKN expression via NMDA receptors (NMDARs). Furthermore, NMDAR antagonist APV, Wnt/ß-catenin signaling suppressor DKK1, or knockout of CX3CR1 alleviated gp120-induced mechanical allodynia in mice, suggesting a critical contribution of the Wnt/ß-catenin/FKN/CX3R1 pathway to gp120-induced pain. These findings collectively suggest that HIV-1 gp120 induces synaptic degeneration in the spinal pain neural circuit by activating microglia via Wnt3a/ß-catenin-regulated FKN expression in neurons.SIGNIFICANCE STATEMENT Synaptic degeneration develops in the spinal cord dorsal horn of HIV patients with chronic pain, but the patients without the pain disorder do not show this neuropathology, indicating a pathogenic contribution of the synaptic degeneration to the development of HIV-associated pain. However, the mechanism underlying the synaptic degeneration is unclear. We report here that HIV-1 gp120, a neurotoxic protein that is specifically associated with the manifestation of pain in HIV patients, induces synapse loss via microglia. Further studies elucidate that gp120 activates microglia by stimulating Wnt/ß-catenin-regulated fractalkine in neuron. The results demonstrate a critical role of microglia in the pathogenesis of HIV-associated synaptic degeneration in the spinal pain neural circuit.

Increased talin-vinculin spatial proximities in livers in response to spotted fever group rickettsial and Ebola virus infections.

Talin and vinculin, both actin-cytoskeleton-related proteins, have been documented to participate in establishing bacterial infections, respectively, as the adapter protein to mediate cytoskeleton-driven dynamics of the plasma membrane. However, little is known regarding the potential role of the talin-vinculin complex during spotted fever group rickettsial and Ebola virus infections, two dreadful infectious diseases in humans. Many functional properties of proteins are determined by their participation in protein-protein complexes, in a temporal and/or spatial manner. To resolve the limitation of application in using mouse primary antibodies on archival, multiple formalin-fixed mouse tissue samples, which were collected from experiments requiring high biocontainment, we developed a practical strategic proximity ligation assay (PLA) capable of employing one primary antibody raised in mouse to probe talin-vinculin spatial proximal complex in mouse tissue. We observed an increase of talin-vinculin spatial proximities in the livers of spotted fever Rickettsia australis or Ebola virus-infected mice when compared with mock mice. Furthermore, using EPAC1-knockout mice, we found that deletion of EPAC1 could suppress the formation of spatial proximal complex of talin-vinculin in rickettsial infections. In addition, we observed increased colocalization between spatial proximity of talin-vinculin and filamentous actin-specific phalloidin staining in single survival mouse from an ordinarily lethal dose of rickettsial or Ebola virus infection. These findings may help to delineate a fresh insight into the mechanisms underlying liver specific pathogenesis during infection with spotted fever rickettsia or Ebola virus in the mouse model.

Neuron activity-induced Wnt signaling up-regulates expression of brain-derived neurotrophic factor in the pain neural circuit.

Brain-derived neurotrophic factor (BDNF) is a master regulator of synaptic plasticity in various neural circuits of the mammalian central nervous system. Neuron activity-induced BDNF gene expression is regulated through the Ca2+/CREB pathway, but other regulatory factors may also be involved in controlling BDNF levels. We report here that Wnt/ß-catenin signaling plays a key role in controlling neuron activity-regulated BDNF expression. Using primary cortical cultures, we show that blockade of Wnt/ß-catenin signaling inhibits the BDNF up-regulation that is induced by activation of the N-methyl-d-aspartic acid (NMDA) receptor and that activation of the Wnt/ß-catenin signaling pathway stimulates BDNF expression. In vivo, Wnt/ß-catenin signaling activated BDNF expression and was required for peripheral pain-induced up-regulation of BDNF in the mouse spine. We also found that conditional deletion of one copy of either Wntless (Wls) or ß-catenin by Nestin-Cre-mediated recombination is sufficient to inhibit the pain-induced up-regulation of BDNF. We further show that the Wnt/ß-catenin/BDNF axis in the spinal neural circuit plays an important role in regulating capsaicin-induced pain. These results indicate that neuron activity-induced Wnt signaling stimulates BDNF expression in the pain neural circuits. We propose that pain-induced Wnt secretion may provide an additional mechanism for intercellular coordination of BDNF expression in the neural circuit.

Mitochondrial superoxide increases excitatory synaptic strength in spinal dorsal horn neurons of neuropathic mice.

Reactive oxygen species has been suggested as a key player in neuropathic pain, causing central sensitization by changing synaptic strengths in spinal dorsal horn neurons. However, it remains unclear as to what type of reactive oxygen species changes what aspect of synaptic strengths for central sensitization in neuropathic pain conditions. In this study, we investigated whether mitochondrial superoxide affects both excitatory and inhibitory synaptic strengths in spinal dorsal horn neurons after peripheral nerve injury. Upregulation of mitochondrial superoxide level by knockout of superoxide dismutase-2 exacerbated neuropathic mechanical hypersensitivity caused by L5 spinal nerve ligation, whereas downregulation of mitochondrial superoxide level by overexpression of superoxide dismutase-2 alleviated the hypersensitivity. In spinal nerve ligation condition, the frequency of miniature excitatory postsynaptic currents increased, while that of miniature inhibitory postsynaptic currents decreased in spinal dorsal horn neurons. Superoxide dismutase-2-knockout augmented, whereas superoxide dismutase-2-overexpression prevented, the spinal nerve ligation-increased miniature excitatory postsynaptic currents frequency. However, superoxide dismutase-2-knockout had no effect on the spinal nerve ligation-decreased miniature inhibitory postsynaptic current frequency, and superoxide dismutase-2-overexpression unexpectedly decreased miniature inhibitory postsynaptic current frequency in the normal condition. When applied to the spinal cord slice during in vitro recordings, mitoTEMPO, a specific scavenger of mitochondrial superoxide, reduced the spinal nerve ligation-increased miniature excitatory postsynaptic currents frequency but failed to normalize the spinal nerve ligation-decreased miniature inhibitory postsynaptic current frequency. These results suggest that in spinal dorsal horn neurons, high levels of mitochondrial superoxide increase excitatory synaptic strength after peripheral nerve injury and contribute to neuropathic mechanical hypersensitivity. However, mitochondrial superoxide does not seem to be involved in the decreased inhibitory synaptic strength in this neuropathic pain condition.

EXPRESS: Oligodendrocytes in HIV-associated pain pathogenesis.

BACKGROUND: Although the contributions of microglia and astrocytes to chronic pain pathogenesis have been a focal point of investigation in recent years, the potential role of oligodendrocytes, another major type of glial cells in the CNS that generates myelin, remains largely unknown. RESULTS: We report here that cell markers of the oligodendrocyte lineage, including NG2, PDGFRa, and Olig2, are significantly increased in the spinal dorsal horn of HIV patients who developed chronic pain. The levels of myelin proteins myelin basic protein and proteolipid protein are also aberrant in the spinal dorsal horn of "pain-positive" HIV patients. Similarly, the oligodendrocyte and myelin markers are up-regulated in the spinal dorsal horn of a mouse model of HIV-1 gp120-induced pain. Surprisingly, the expression of gp120-induced mechanical allodynia appears intact up to 4 h after myelin basic protein is knocked down or knocked out. CONCLUSION: These findings suggest that oligodendrocytes are reactive during the pathogenesis of HIV-associated pain. However, interfering with myelination does not alter the induction of gp120-induced pain.

Gp120 in the pathogenesis of human immunodeficiency virus-associated pain.

OBJECTIVE: Chronic pain is a common neurological comorbidity of human immunodeficiency virus (HIV)-1 infection, but the etiological cause remains elusive. The objective of this study was to identify the HIV-1 causal factor that critically contributes to the pathogenesis of HIV-associated pain. METHODS: We first compared the levels of HIV-1 proteins in postmortem tissues of the spinal cord dorsal horn (SDH) from HIV-1/acquired immunodeficiency syndrome patients who developed chronic pain (pain-positive HIV-1 patients) and HIV-1 patients who did not develop chronic pain (pain-negative HIV-1 patients). Then we used the HIV-1 protein that was specifically increased in the pain-positive patients to generate mouse models. Finally, we performed comparative analyses on the pathological changes in the models and the HIV-1 patients. RESULTS: We found that HIV-1 gp120 was significantly higher in pain-positive HIV-1 patients (vs pain-negative HIV-1 patients). This finding suggested that gp120 was a potential causal factor of the HIV-associated pain. To test this hypothesis, we used a mouse model generated by intrathecal injection of gp120 and compared the pathologies of the model and the pain-positive human HIV-1 patients. The results showed that the mouse model and pain-positive human HIV-1 patients developed extensive similarities in their pathological phenotypes, including pain behaviors, peripheral neuropathy, glial reactivation, synapse degeneration, and aberrant activation of pain-related signaling pathways in the SDH. INTERPRETATION: Our findings suggest that gp120 may critically contribute to the pathogenesis of HIV-associated pain.

Wingless-type mammary tumor virus integration site family, member 5A (Wnt5a) regulates human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein 120 (gp120)-induced expression of pro-inflammatory cytokines via the Ca2+/calmodulin-dependent protein kinase II (CaMKII) and c-Jun N-terminal kinase (JNK) signaling pathways.

BACKGROUND: HIV-1 infection causes chronic neuroinflammation in the central nervous system (CNS). RESULTS: The spinal cytokine up-regulation induced by HIV-1 gp120 protein depends on Wnt5a/CaMKII and/or Wnt5a/JNK pathways. CONCLUSION: gp120 stimulates cytokine expression in the spinal cord dorsal horn by activating Wnt5a signaling. SIGNIFICANCE: The finding reveals Wnt signaling-mediated novel mechanisms by which HIV-1 may cause neuroinflammation. Chronic expression of pro-inflammatory cytokines critically contributes to the pathogenesis of HIV-associated neurological disorders (HANDs), but the host mechanism that regulates the HIV-induced cytokine expression in the CNS remains elusive. Here, we present evidence for a crucial role of Wnt5a signaling in the expression of pro-inflammatory cytokines in the spinal cord induced by a major HIV-envelope protein, gp120. Wnt5a is mainly expressed in spinal neurons, and rapidly up-regulated by intrathecal injection (i.t.) of gp120. We show that inhibition of Wnt5a by specific antagonists blocks gp120-induced up-regulation of IL-1ß, IL-6, and TNF-α in the spinal cord. Conversely, injection (i.t.) of purified recombinant Wnt5a stimulates the expression of these cytokines. To elucidate the role of the Wnt5a-regulated signaling pathways in gp120-induced cytokine expression, we have focused on CaMKII and JNKs, the well characterized down-stream targets of Wnt5a signaling. We find that Wnt5a is required for gp120 to activate CaMKII and JNK signaling. Furthermore, we demonstrate that the Wnt5a/CaMKII pathway is critical for the gp120-induced expression of IL-1ß, whereas the Wnt5a/JNK pathway is for TNF-α expression. Meanwhile, the expression of IL-6 is co-regulated by both pathways. These results collectively suggest that Wnt5a signaling cascades play a crucial role in the regulation of gp120-induced expression of pro-inflammatory cytokines in the CNS.

Neural Circuitry Polarization in the Spinal Dorsal Horn (SDH): A Novel Form of Dysregulated Circuitry Plasticity during Pain Pathogenesis.

Pathological pain emerges from nociceptive system dysfunction, resulting in heightened pain circuit activity. Various forms of circuitry plasticity, such as central sensitization, synaptic plasticity, homeostatic plasticity, and excitation/inhibition balance, contribute to the malfunction of neural circuits during pain pathogenesis. Recently, a new form of plasticity in the spinal dorsal horn (SDH), named neural circuit polarization (NCP), was discovered in pain models induced by HIV-1 gp120 and chronic morphine administration. NCP manifests as an increase in excitatory postsynaptic currents (EPSCs) in excitatory neurons and a decrease in EPSCs in inhibitory neurons, presumably facilitating hyperactivation of pain circuits. The expression of NCP is associated with astrogliosis. Ablation of reactive astrocytes or suppression of astrogliosis blocks NCP and, concomitantly, the development of gp120- or morphine-induced pain. In this review, we aim to compare and integrate NCP with other forms of plasticity in pain circuits to improve the understanding of the pathogenic contribution of NCP and its cooperation with other forms of circuitry plasticity during the development of pathological pain.

Chronic-pain-associated astrocytic reaction in the spinal cord dorsal horn of human immunodeficiency virus-infected patients.

Studies with animal models have suggested that reaction of glia, including microglia and astrocytes, critically contributes to the development and maintenance of chronic pain. However, the involvement of glial reaction in human chronic pain is unclear. We performed analyses to compare the glial reaction profiles in the spinal dorsal horn (SDH) from three cohorts of sex- and age-matched human postmortem tissues: (1) HIV-negative patients, (2) HIV-positive patients without chronic pain, and (3) HIV patients with chronic pain. Our results indicate that the expression levels of CD11b and Iba1, commonly used for labeling microglial cells, did not differ in the three patient groups. However, GFAP and S100ß, often used for labeling astrocytes, were specifically upregulated in the SDH of the "pain-positive" HIV patients but not in the "pain-negative" HIV patients. In addition, proinflammatory cytokines, TNFα and IL-1ß, were specifically increased in the SDH of pain-positive HIV patients. Furthermore, proteins in the MAPK signaling pathway, including pERK, pCREB and c-Fos, were also upregulated in the SDH of pain-positive HIV patients. Our findings suggest that reaction of astrocytes in the SDH may play a role during the maintenance phase of HIV-associated chronic pain.

Activation of NMDA receptors upregulates a disintegrin and metalloproteinase 10 via a Wnt/MAPK signaling pathway.

A disintegrin and metalloproteinase 10 (ADAM10) is the constitutive α-secretase that governs the nonamyloidogenic pathway of ß-amyloid precursor protein processing and is an attractive drug target for treating Alzheimer's disease. To date, little is known about the mechanism by which ADAM10 is regulated in neurons. Using mouse primary cortical neurons, we show here that NMDA receptor (NMDAR) activation led to upregulation of the genes encoding ADAM10 and ß-catenin proteins. Interestingly, the ADAM10 upregulation was abolished by inhibitors of Wnt/ß-catenin signaling. Conversely, activation of the Wnt/ß-catenin signaling pathway by recombinant Wnt3a stimulated ADAM10 expression. We further showed that both the NMDAR- and Wnt3a-induced ADAM10 upregulation was blocked by ERK inhibitors. We suggest that the NMDARs control ADAM10 expression via a Wnt/MAPK signaling pathway.

Gonadal hormone-dependent nociceptor sensitization maintains nociplastic pain state in female mice.

ABSTRACT: Nociplastic pain conditions develop predominantly in women. We recently established a murine nociplastic pain model by applying postinjury thermal (40°C) stimulation to an injured (capsaicin-injected) area, triggering a transition to a nociplastic pain state manifesting as persistent mechanical hypersensitivity outside of the previously injured area. The nociplastic pain state was centrally maintained by spinal microglia in males but peripherally by ongoing afferent activity at the previously injured area in females. Here, we investigated whether gonadal hormones are critical for the development of this peripherally maintained nociplastic pain state in females. Although the transition to a nociplastic pain state still occurred in ovariectomized females, the pain state was maintained neither by ongoing afferent activity at the previously injured area nor by spinal microglia. Estradiol reconstitution a week before the injury plus postinjury stimulation, but not after the transition had already occurred, restored the development of peripherally maintained nociplastic mechanical hypersensitivity in ovariectomized females. G protein-coupled estrogen receptor antagonism during the transition phase mimicked ovariectomy in gonad-intact females, whereas the receptor antagonism after the transition gradually alleviated the nociplastic mechanical hypersensitivity. At the previously injured area, afferents responsive to allyl isothiocyanate (AITC), a TRPA1 agonist, contributed to the maintenance of nociplastic mechanical hypersensitivity in gonad-intact females. In ex vivo skin-nerve preparations, only AITC-responsive afferents from the nociplastic pain model in gonad-intact females showed ongoing activities greater than control. These results suggest that gonadal hormones are critical for peripherally maintained nociplastic pain state in females by sensitizing AITC-responsive afferents to be persistently active.

The antitumor effect of mycelia extract of the medicinal macrofungus Inonotus hispidus on HeLa cells via the mitochondrial-mediated pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Inonotus hispidus (I. hispidus), known as shaggy bracket, has been used extensively in China and some East Asian countries as a traditional medicinal macrofungus to treat difficult diseases, such as diabetes, gout, and arthritis. Modern pharmacological research has shown that I. hispidus has an important application value in antitumor treatment. However, the main anti-cervical cancer activity substances from its mycelia and its mechanisms are still not clear. AIMS OF THE STUDY: To enrich the germplasm resources of I. hispidus, to reveal the antitumor activity of the extract from the mycelium of I. hispidus against cervical cancer, and to preliminarily analyze its action mechanism. MATERIALS AND METHODS: The SH3 strain was isolated from wild fruiting bodies and identified by morphology and molecular biology. The antitumor active component from the mycelium of I. hispidus was isolated and identified with liquid chromatography-tandem mass spectrometry. The cell viability was assessed by MTT assay. The cell cycle distribution, apoptotic cell detection, and mitochondrial membrane potential were detected by flow cytometer. The expression of apoptosis-related proteins was assessed by Western blotting. The inhibition of tumor growth in vivo was assessed by a mouse xenograft model. RESULTS: The SH3 strain was isolated and identified as a new strain of I. hispidus. The antitumor active component containing cyclic peptides from the mycelium of I. hispidus (CCM) was isolated for the first time. In addition, we found that CCM had a strong inhibitory effect on HeLa proliferation in vitro and in vivo. Mechanically, the CCM blocked the cell cycle at the G0/G1 phase, decreased the mitochondrial membrane potential, and eventually promoted apoptosis of HeLa cells through the mitochondria-mediated pathway by upregulating the expression levels of Bax, cytochrome C, cleaved caspase-9, and cleaved caspase-3 and downregulating the expression level of Bcl-2. CONCLUSIONS: Our study not only enriches the strain resources of I. hispidus but also confirms that the mycelium of this strain has active components that can inhibit cervical cancer. This is highly significant for the development of active drugs and drug lead molecules for treating cervical cancer.

Spinal astrocytic MeCP2 regulates Kir4.1 for the maintenance of chronic hyperalgesia in neuropathic pain.

Astrocyte activation in the spinal dorsal horn may play an important role in the development of chronic neuropathic pain, but the mechanisms involved in astrocyte activation and their modulatory effects remain unknown. The inward rectifying potassium channel protein 4.1 (Kir4.1) is the most important background K+ channel in astrocytes. However, how Kir4.1 is regulated and contributes to behavioral hyperalgesia in chronic pain is unknown. In this study, single-cell RNA sequencing analysis indicated that the expression levels of both Kir4.1 and Methyl-CpG-binding protein 2 (MeCP2) were decreased in spinal astrocytes after chronic constriction injury (CCI) in a mouse model. Conditional knockout of the Kir4.1 channel in spinal astrocytes led to hyperalgesia, and overexpression of the Kir4.1 channel in spinal cord relieved CCI-induced hyperalgesia. Expression of spinal Kir4.1 after CCI was regulated by MeCP2. Electrophysiological recording in spinal slices showed that knockdown of Kir4.1 significantly up-regulated the excitability of astrocytes and then functionally changed the firing patterns of neurons in dorsal spinal cord. Therefore, targeting spinal Kir4.1 may be a therapeutic approach for hyperalgesia in chronic neuropathic pain.

Regulation of Wnt signaling by nociceptive input in animal models.

BACKGROUND: Central sensitization-associated synaptic plasticity in the spinal cord dorsal horn (SCDH) critically contributes to the development of chronic pain, but understanding of the underlying molecular pathways is still incomplete. Emerging evidence suggests that Wnt signaling plays a crucial role in regulation of synaptic plasticity. Little is known about the potential function of the Wnt signaling cascades in chronic pain development. RESULTS: Fluorescent immunostaining results indicate that ß-catenin, an essential protein in the canonical Wnt signaling pathway, is expressed in the superficial layers of the mouse SCDH with enrichment at synapses in lamina II. In addition, Wnt3a, a prototypic Wnt ligand that activates the canonical pathway, is also enriched in the superficial layers. Immunoblotting analysis indicates that both Wnt3a a ß-catenin are up-regulated in the SCDH of various mouse pain models created by hind-paw injection of capsaicin, intrathecal (i.t.) injection of HIV-gp120 protein or spinal nerve ligation (SNL). Furthermore, Wnt5a, a prototypic Wnt ligand for non-canonical pathways, and its receptor Ror2 are also up-regulated in the SCDH of these models. CONCLUSION: Our results suggest that Wnt signaling pathways are regulated by nociceptive input. The activation of Wnt signaling may regulate the expression of spinal central sensitization during the development of acute and chronic pain.

Reactive astrocytes in pain neural circuit pathogenesis.

Reactive astrocytes are commonly activated in the spinal dorsal horn (SDH) of various animal models of pathological pain. Previous investigations suggest an association between astrogliosis and pain pathogenesis. However, our understanding of the mechanisms underlying astrogliosis activation and the contributions of reactive astrocytes to pain neural circuit malfunction is rudimentary. This short review highlights recent advances in these areas.