Inhibition of CaMKIV relieves streptozotocin-induced diabetic neuropathic pain through regulation of HMGB1

High mobility group box-1: A therapeutic target for analgesia and associated symptoms in chronic pain

The number of patients with chronic pain continues to increase against the background of an ageing society and a high incidence of various epidemics and disasters. One factor contributing to this situation is the absence of truly effective analgesics. Chronic pain is a persistent stress for the organism and can trigger a variety of neuropsychiatric symptoms. Hence, the search for useful analgesic targets is currently being intensified worldwide, and it is anticipated that the key to success may be molecules involved in emotional as well as sensory systems. High mobility group box-1 (HMGB1) has attracted attention as a therapeutic target for a variety of diseases. It is a very unique molecule having a dual role as a nuclear protein while also functioning as an inflammatory agent outside the cell. In recent years, numerous studies have shown that HMGB1 acts as a pain inducer in primary sensory nerves and the spinal dorsal horn. In addition, HMGB1 can function in the brain, and is involved in the symptoms of depression, anxiety and cognitive dysfunction that accompany chronic pain. In this review, we will summarize recent research and discuss the potential of HMGB1 as a useful drug target for chronic pain.

The role of protein kinases in diabetic neuropathic pain: an update review

Objectives

Diabetic neuropathic pain (DNP) is a debilitating symptom of diabetic neuropathy which seriously impairs patient's quality of life. Currently, there is no specific therapy for DNP except for duloxetine and gabapentin that show limited utility in alleviating DNP. The present review aims to discuss the central role of protein kinases in the pathogenesis of DNP and their therapeutic modulation.

Methods

Scopus, PubMed, and Google scholar were searched up to January 2022 to find relevant studies with English language in which the roles of proteins kinases in DNP were examined.

Results

DNP is associated with hyperactivity in pain sensory neurons and therapies aim to specifically suppress redundant discharges in these neurons without affecting the activity of other sensory and motor neurons. Transient receptor potential vanilloid 1 (TRPV1) and purinergic 2 × 7 receptors (P2 × 7R) are two receptor channels, highly expressed in pain sensory neurons and their blockade produces remarkable analgesic effects in DNP. The activities of receptor channels are mainly regulated by the protein kinases whose modulation provides remarkable analgesic effects in DNP models.

Conclusion

Capsaicin, TRPV1 modulator, is the only agent successfully examined in clinical trials with promising effects in patients with DNP. Current data suggest that blocking calcium calmodulin dependent protein kinase II (CaMKII) is superior to other approaches, considering its pivotal role in regulating the pain neuron potentials. By this means, DNP alleviation is achievable without affecting the activity of other sensory or motor neurons.

Magnesium promotes osteogenesis via increasing OPN expression and activating CaM/CaMKIV/CREB1 pathway

Magnesium (Mg) based alloy has been used as a biodegradable implant for fracture repair with considerable efficacy, and it has been proved that magnesium ion (Mg²⁺ ), one of the degradation products, could stimulate osteogenesis. Here, we investigated the osteogenesis property of magnesium both in vitro and in vivo, and to identify the cellular and molecular mechanisms that mediate these effects. Results showed that magnesium exerts a dose-dependent increase in the proliferation of MC3T3 and MG63 cells, and in the expression of osteopontin (OPN), a promising biomarker of osteogenesis. Subsequently, the protein-protein interaction (PPI) network analysis showed the interactions between calmodulin (CaM) and calmodulin-dependent protein kinase (CaMK) and CREB1. The ratio of p-CaMKIV/CaMKIV and p-CREB1/CREB were increased at protein level in MC3T3 and MG63 cells after treatment with Mg²⁺ . Dual-luciferase reporter gene assay showed that p-CREB1 could directly bind to OPN promoter and up-regulate the transcription of OPN after nuclear entry. Meanwhile, the expression of OPN and p-CREB1, which increased after Mg²⁺ treatment, was down-regulated by sh-CaMKIV or sh-CREB1. Moreover, the mineralized deposit and expression of OPN were reduced after treatment with an inhibitor of CaMKIV, KN93. In addition, massive cavities in the cortical bone around the Mg screw were showed in vivo after injection of KN93. These data indicated that the osteogenic effect of Mg is related to the activation OPN through CaM/CaMKIV/CREB1 signaling pathway.

Roles of Long Non-coding RNAs in the Development of Chronic Pain

Chronic pain, a severe public health issue, affects the quality of life of patients and results in a major socioeconomic burden. Only limited drug treatments for chronic pain are available, and they have insufficient efficacy. Recent studies have found that the expression of long non-coding RNAs (lncRNAs) is dysregulated in various chronic pain models, including chronic neuropathic pain, chronic inflammatory pain, and chronic cancer-related pain. Studies have also explored the effect of these dysregulated lncRNAs on the activation of microRNAs, inflammatory cytokines, and so on. These mechanisms have been widely demonstrated to play a critical role in the development of chronic pain. The findings of these studies indicate the significant roles of dysregulated lncRNAs in chronic pain in the dorsal root ganglion and spinal cord, following peripheral or central nerve lesions. This review summarizes the mechanism underlying the abnormal expression of lncRNAs in the development of chronic pain induced by peripheral nerve injury, diabetic neuropathy, inflammatory response, trigeminal neuralgia, spinal cord injury, cancer metastasis, and other conditions. Understanding the effect of lncRNAs may provide a novel insight that targeting lncRNAs could be a potential candidate for therapeutic intervention in chronic pain.

Sevoflurane induces inflammation of microglia in hippocampus of neonatal rats by inhibiting Wnt/β-Catenin/CaMKIV pathway

OBJECTIVE

To investigate the effect of sevoflurane on inflammation of microglia in hippocampus of neonatal rats, and to investigate whether the related mechanism is related to Wnt/β-Catenin/CaMKIV pathway.

METHODS

Neonatal rats were anesthetized with 2% or 3% sevoflurane for 4 h a day for 3 consecutive days. Water maze test was used to detect the effect of sevoflurane anesthesia on memory function of neonatal rats. H&E and Nissl staining were used to observe the pathological damage of hippocampal area of neonatal rats induced by sevoflurane anesthesia. The expression of microglial marker Iba-1 was detected by Immunofluorescence. Immunofluorescence and WB were used to detect the expression CD32b, CD86, TNF-α, IL-6, Wnt3a, β-Catenin and CaMKIV in hippocampus. To further explore the related mechanism, Wnt-3α inhibitor and activator was treated to study the effect of sevoflurane on microglial inflammation in hippocampus of neonatal rats.

RESULTS

Sevoflurane anesthesia significantly increased escape latency time, reduced platform crossing times, and damaged the learning and memory ability of neonatal rats. H&E and Nissl staining results showed that sevoflurane anesthesia caused obvious damage to the hippocampus of neonatal rats. Sevoflurane anesthesia promoted the expression of Iba-1 and activated microglia. Sevoflurane anesthesia not only significantly increased the positive expression of CD32b, CD86, TNF-α and IL-6, but also decreased the expression of Wnt3a, β-Catenin and CaMKIV. These results suggested that sevoflurane inhibited Wnt/β-Catenin/CaMKIV pathway.

CONCLUSION

Sevoflurane induces inflammation of microglia in hippocampus of neonatal rats by inhibiting Wnt/β-Catenin/CaMKIV pathway.

Downregulation of lncRNA FIRRE relieved the neuropathic pain of female mice by suppressing HMGB1 expression

Long non-coding RNAs are novel regulators in neuropathic pain. In this study, we aimed to explore the role and the mechanism of lncRNA FIRRE in regulating the secretion of microglial cells-derived proinflammatory cytokines in neuropathic pain. The female mouse model of neuropathic pain was established by bilateral chronic constriction injury (CCI) surgery. The mouse primary microglial cells were induced by lipopolysaccharide (LPS). The interaction between FIRRE and high mobility group box 1 (HMGB1) was assessed by RNA immunoprecipitation, RNA pull-down, and ubiquitination assays. FIRRE expression was upregulated in the spinal cord tissue of female CCI mice and LPS-induced microglial cells. The concentrations of IL-1β, TNF-α, and IL-6 from LPS-induced microglial cells were reduced by FIRRE knockdown. FIRRE bound to HMGB1 and negatively regulated its protein level. The ubiquitination degradation of HMGB1 was promoted by FIRRE silence. The HMGB1 over-expression reversed the inhibitory effect of FIRRE silence on the secretion of IL-1β, TNF-α, and IL-6 from LPS-induced microglial cells. The in vivo experiment showed that FIRRE knockdown alleviated neuropathic pain of CCI female mice. Our findings indicated that lncRNA FIRRE downregulation inhibits the secretion of microglial cells-derived proinflammatory cytokines by decreasing HMGB1 expression, thereby relieving neuropathic pain of female mice.

Differential Characteristics of HMGB2 Versus HMGB1 and their Perspectives in Ovary and Prostate Cancer

We have summarized common and differential functions of HMGB1 and HMGB2 proteins with reference to pathological processes, with a special focus on cancer. Currently, several "omic" approaches help us compare the relative expression of these 2 proteins in healthy and cancerous human specimens, as well as in a wide range of cancer-derived cell lines, or in fetal versus adult cells. Molecules that interfere with HMGB1 functions, though through different mechanisms, have been extensively tested as therapeutic agents in animal models in recent years, and their effects are summarized. The review concludes with a discussion on the perspectives of HMGB molecules as targets in prostate and ovarian cancers.

The role of CAMKK2 polymorphisms in HIV-associated sensory neuropathy in South Africans

Human immunodeficiency virus-associated sensory neuropathy (HIV-SN) is a common neurological complication of HIV infection. It affected 57% of South African patients whose antiretroviral therapy (ART) included stavudine and was influenced by genotypes of the P2X-block (P2X7R, P2X4R and CAMKK2). We investigate associations between HIV-SN and P2X-block genotypes in patients who never received stavudine. An adjacent gene, ANAPC5, was included. 75 HIV+ individuals were assessed using the Brief Peripheral Neuropathy Screen before treatment and after 6-8 months on stavudine-free regimens. DNA was genotyped for 48 polymorphisms across the four genes using an OpenArray™ platform. Haplotypes were derived using fastPHASE. Associations with HIV-SN were assessed using bivariate and multivariate analyses. Nine individuals (12%) were diagnosed with HIV-SN prior to ART and a further 20 individuals (27%) developed HIV-SN within 6-8 months. Five polymorphisms, rs503720*G (OR = 133) in P2X7R, rs10849861*A (OR = 5.99), rs1653586*T (OR = 67.8) and rs11065504*C (OR = 0.02) in CAMKK2, and rs2089886*A (OR = 6.68) in ANAPC5, associated with HIV-SN after adjusting for body weight, nadir CD4 T-cell counts and prior tuberculosis (model p < 0.0001, n = 69, Pseudo R² = 0.54). Three CAMKK2 haplotypes were associated with HIV-SN (OR = 2.82, 3.42 and 6.85) after adjusting for body weight, nadir CD4 T-cell counts and prior tuberculosis (model p < 0.0005, n = 71, Pseudo R² = 0.26). The results support a role for CAMKK2 in HIV-SN, independent of mechanisms invoked by stavudine. SIGNIFICANCE STATEMENT: HIV-associated sensory neuropathy (HIV-SN) remains a clinically relevant complication of HIV infection and its treatment, affecting 38% of patients treated without neurotoxic stavudine. HIV-SN can impact an individual's ability to work and quality of life, with few effective therapeutic options, so an understanding of the underlying mechanisms would have clinical value. We confirm that CAMKK2 polymorphisms and haplotypes influence susceptibility to HIV-SN in South Africans treated without stavudine. This provides further evidence for a role for the protein encoded by CAMKK2 in the pathogenesis of HIV-SN, independent of mechanisms initiated by stavudine.

Role of high-mobility group box 1 and its modulation by thrombomodulin/thrombin axis in neuropathic and inflammatory pain

High-mobility group box 1 (HMGB1), a nuclear protein, once released to the extracellular space, facilitates pain signals as well as inflammation. Intraplantar or intraspinal application of HMGB1 elicits hyperalgesia/allodynia in rodents by activating the advanced glycosylation end-product specific receptor (receptor for advanced glycation end-products; RAGE) or Toll-like receptor 4 (TLR4). Endogenous HMGB1 derived from neurons, perineuronal cells or immune cells accumulating in the dorsal root ganglion or sensory nerves participates in somatic and visceral pain consisting of neuropathic and/or inflammatory components. Endothelial thrombomodulin (TM) and recombinant human soluble TM, TMα, markedly increase thrombin-dependent degradation of HMGB1, and systemic administration of TMα prevents and reverses various HMGB1-dependent pathological pain. Low MW compounds that directly inactivate HMGB1 or antagonize HMGB1-targeted receptors would be useful to reduce various forms of intractable pain. Thus, HMGB1 and its receptors are considered to serve as promising targets in developing novel agents to prevent or treat pathological pain. LINKED ARTICLES: This article is part of a themed issue on Neurochemistry in Japan. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.4/issuetoc.

Genome wide analysis of gene expression changes in skin from patients with type 2 diabetes

Non-healing chronic ulcers are a serious complication of diabetes and are a major healthcare problem. While a host of treatments have been explored to heal or prevent these ulcers from forming, these treatments have not been found to be consistently effective in clinical trials. An understanding of the changes in gene expression in the skin of diabetic patients may provide insight into the processes and mechanisms that precede the formation of non-healing ulcers. In this study, we investigated genome wide changes in gene expression in skin between patients with type 2 diabetes and non-diabetic patients using next generation sequencing. We compared the gene expression in skin samples taken from 27 patients (13 with type 2 diabetes and 14 non-diabetic). This information may be useful in identifying the causal factors and potential therapeutic targets for the prevention and treatment of diabetic related diseases.

Regulation of Multifunctional Calcium/Calmodulin Stimulated Protein Kinases by Molecular Targeting

Multifunctional calcium/calmodulin-stimulated protein kinases control a broad range of cellular functions in a multitude of cell types. This family of kinases contain several structural similarities and all are regulated by phosphorylation, which either activates, inhibits or modulates their kinase activity. As these protein kinases are widely or ubiquitously expressed, and yet regulate a broad range of different cellular functions, additional levels of regulation exist that control these cell-specific functions. Of particular importance for this specificity of function for multifunctional kinases is the expression of specific binding proteins that mediate molecular targeting. These molecular targeting mechanisms allow pools of kinase in different cells, or parts of a cell, to respond differently to activation and produce different functional outcomes.

Dexmedetomidine attenuates P2X4 and NLRP3 expression in the spine of rats with diabetic neuropathic pain

Purpose:

To evaluate the effects of Dexmedetomidine (Dex) on spinal pathology and inflammatory factor in a rat model of Diabetic neuropathic pain (DNP).

Methods:

The rats were divided into 3 groups (eight in each group): normal group (N group), diabetic neuropathic pain model group (DNP group), and DNP model with dexmedetomidine (Dex group). The rat model of diabetes was established with intraperitoneal streptozotocin (STZ) injections. Nerve cell ultrastructure was evaluated with transmission electron microscopy (TEM). The mechanical withdrawal threshold (MWT) and motor nerve conduction velocity (MNCV) tests documented that DNP rat model was characterized by a decreased pain threshold and nerve conduction velocity.

Results:

Dex restored the phenotype of neurocytes, reduced the extent of demyelination and improved MWT and MNCV of DNP-treated rats (P=0.01, P=0.038, respectively). The expression of three pain-and inflammation-associated factors (P2X4, NLRP3, and IL-IP) was significantly upregulated at the protein level in DNP rats, and this change was reversed by Dex administration (P=0.0022, P=0.0092, P=0.0028, respectively).

Conclusion:

The P2X4/NLRP3 signaling pathway is implicated in the development and presence of DNP in vivo, and Dex protects from this disorder.

High Mobility Group Box-1 and Diabetes Mellitus Complications: State of the Art and Future Perspectives

Diabetes mellitus (DM) is an endemic disease, with growing health and social costs. The complications of diabetes can affect potentially all parts of the human body, from the heart to the kidneys, peripheral and central nervous system, and the vascular bed. Although many mechanisms have been studied, not all players responsible for these complications have been defined yet. High Mobility Group Box-1 (HMGB1) is a non-histone nuclear protein that has been implicated in many pathological processes, from sepsis to ischemia. The purpose of this review is to take stock of all the most recent data available on the role of HMGB1 in the complications of DM.

Polymorphisms in CAMKK2 associate with susceptibility to sensory neuropathy in HIV patients treated without stavudine

HIV-associated sensory neuropathy (HIV-SN) is a debilitating neurological complication of HIV infection potentiated by the antiretroviral drug stavudine. While stavudine is no longer used, HIV-SN now affects around 15% of HIV+ Indonesians. Here, we investigate whether polymorphisms within the P2X-block (P2X4R, P2X7R, CAMKK2) and/or ANAPC5 mark susceptibility to HIV-SN in this setting. As polymorphisms in these genes associated with HIV-SN in African HIV patients receiving stavudine, the comparison can identify mechanisms independent of stavudine. HIV patients who had never used stavudine (n = 202) attending clinics in Jakarta were screened for neuropathy using the AIDS Clinical Trials Group Brief Peripheral Neuropathy Screen. Open-array technology was used to type 48 polymorphisms spanning the four genes. Haplotypes were derived for each gene using fastPHASE. Haplogroups were constructed with median-joining methods. Multivariable models optimally predicting HIV-SN were based on factors achieving p < 0.2 in bivariate analyses. Minor alleles of three co-inherited polymorphisms in CAMKK2 (rs7975295*C, rs1560568*A, rs1132780*T) associated with a reduced prevalence of HIV-SN individually and after adjusting for lower CD4 T cell count and viremia (p = 0.0002, pseudo R² = 0.11). The optimal model for haplotypes linked HIV-SN with viremia and lower current CD4 T cell count, plus CAMKK2 haplotypes 6 and 11 and P2X7R haplotypes 2 and 12 (p = 0.0002; pseudo R² = 0.11). CAMKK2 haplogroup A (includes 16 haplotypes and all instances of rs7975295*C, rs1560568*A, rs1132780*T) associated with reduced rates of HIV-SN (p = 0.02, OR = 0.43 CI = 0.21-0.88). These findings support a protective role for these three alleles, suggesting a role in the pathogenesis of HIV-SN that is independent of stavudine.

DNA binding protein HMGB1 secreted by activated microglia promotes the apoptosis of hippocampal neurons in diabetes complicated with OSA

Type 2 diabetes mellitus (T2DM) complicated with obstructive sleep apnea (OSA) may cause neuronal apoptosis and cognitive deficits, but the underlying mechanisms remain unclear. We aimed to determine the relationship between the activation of microglia and the apoptosis of hippocampal neurons, specifically in terms of high mobility group box-1 (HMGB1), after high glucose (HG) and intermittent hypoxia (IH) exposure. Diabetic KK-Ay mice and non-diabetic C57BL/6J mice (C57 mice) underwent IH or normoxia (control) exposure for 4 weeks. Cognitive function, microglial activation and hippocampal neuronal apoptosis were assessed after IH or normoxia exposure. Compared with C57 control mice, KK-Ay control mice exhibited increased cognitive dysfunction, microglial activation and hippocampal neuronal apoptosis. There were no differences between untreated KK-Ay control mice and C57 mice that had been exposed to IH. The abovementioned responses were aggravated in IH-exposed KK-Ay mice compared with control KK-Ay mice. In vitro, a cellular co-culture experiment showed that HG combined with IH could activate BV2 microglia, leading to the release of neuroinflammatory factors (ROS, TNF-α, IL-1β) and mediating the apoptosis of HT22 cells via the PI3K/Akt/GSK-3β signaling pathway. Meanwhile, HMGB1 was actively secreted into the extracellular environment from activated BV2 microglia. As a proinflammatory factor, it was able to sustain microglial activation by directly acting on those cells. The activation promoted positive feedback and aggravated neuronal damage further. In a cellular monoculture or co-culture system, HMGB1 siRNA was able to alleviate the activation of BV2 cells and the apoptosis of HT22 cells induced by HG combined with IH. Our object is to show that inhibition of HMGB1 may break the vicious cycle to prevent or treat neuroinflammation and hippocampal neuronal apoptosis caused by T2DM complicated with OSA.