Integrated traditional Chinese medicine alleviates sciatica while regulating gene expression in peripheral blood.

BACKGROUND: Although integrated traditional Chinese medicine (TCM) has long been indicated to be effective in the treatment of sciatica and is widely used in the management of this condition, the mechanism by which integrated TCM alleviates sciatica has not yet been fully defined, and the effect of integrated TCM on gene expression in the peripheral blood of patients with sciatica is still unknown. We performed this study to investigate the effect of integrated TCM on peripheral blood gene expression in patients with sciatica and to explore new clues for studying the mechanism of integrated TCM in alleviating sciatica. METHODS: We used a microarray to identify differentially expressed genes (DEGs) in the peripheral blood of patients with sciatica and healthy controls (DEGs-baseline), bioinformatic analysis to reveal the characteristics of DEGs-baseline, and the key genes that contribute to the gene dysregulation. A microarray was also used to identify DEGs in the peripheral blood of patients with sciatica after integrated TCM treatment compared with those at baseline, and the expression levels of DEGs were validated by qRT-PCR. RESULTS: We identified 153 DEGs-baseline, which included 131 upregulated genes and 22 downregulated genes. Bioinformatic analysis revealed that most of the DEGs-baseline were related to immunity and the inflammatory response and that TLR4, MMP9, MPO, CAMP, RETN, TLR5, and IL1RN were key genes involved in the dysregulation of genes in the peripheral blood of patients with sciatica. The expression levels of TLR5, IL1RN, SLC8A1, RBM20, GPER1, IL27, SOCS1, and GRTP1-AS1 were decreased in the peripheral blood of patients after integrated TCM treatment compared with that at baseline, which was accompanied by relief of pain. CONCLUSION: Integrated TCM treatment relieved pain while regulating the gene expression of TLR5, IL1RN, SLC8A1, RBM20, GPER1, IL27, SOCS1, and GRTP1-AS1 in the peripheral blood of patients with sciatica. Our study provides new clues for studying the mechanism of TCM in treating sciatica.

TRPV1, Targeted by miR-338-3p, Induces Neuropathic Pain by Interacting with NECAB2.

A variety of studies have proposed that transient receptor potential vanilloid 1 (TRPV1) is involved in the progression of multiple diseases, including neuropathic pain. Although increased expression of TRPV1 in chronic constriction injury was described earlier, the underlying regulatory mechanisms of TRPV1 in neuropathic pain remain largely unknown. In our study, we constructed a chronic constriction injury (CCI) rat model to deeply analyze the mechanisms underlying TRPV1. RT-qPCR-indicated TRPV1 mRNA and protein expression were extremely upregulated in CCI rat dorsal spinal cord tissues. Then, TRPV1 was corroborated to interact with N-terminal EF-hand Ca2+-binding protein 2 (NECAB2). The mRNA and protein levels of NECAB2 were increased in CCI tissues. Moreover, TRPV1 and NECAB2 together regulated nociceptive procession-associated protein metabotropic glutamate receptor 5 (mGluR5), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), and Ca2+ in isolated microglia of CCI rats. Moreover, TRPV1 upregulation apparently increased mechanical allodynia and thermal hyperalgesia as well as the expression of inflammation-associated genes (COX-2, TNF-α, and IL-6). In addition, downregulation of NECAB2 significantly decreased mechanical allodynia and thermal hyperalgesia as well as the expression of COX-2, TNF-α, and IL-6. Furthermore, TRPV1 was confirmed to be a downstream target of miR-338-3p. TRPV1 overexpression abolished the inhibitory effect by miR-338-3p elevation on neuropathic pain development. In summary, this study proved TRPV1, targeted by miR-338-3p, induced neuropathic pain by interacting with NECAB2, which provides a potential therapeutic target for neuropathic pain treatment.

DGCR5 attenuates neuropathic pain through sponging miR-330-3p and regulating PDCD4 in CCI rat models.

Neuropathic pain caused by somatosensory nervous system dysfunction is a serious public health problem. Some long noncoding RNAs (lncRNAs) can participate in physiological processes involved in neuropathic pain. However, the effects of lncRNA DGCR5 in neuropathic pain have not been explored. Therefore, in our current study, we concentrated on the biological roles of DGCR5 in neuropathic pain. Here, it was observed that DGCR5 was significantly decreased in chronic sciatic nerve injury (CCI) rat models. DGCR5 overexpression was able to alleviate neuropathic pain development including mechanical and thermal hyperalgesia. In addition, the current understanding of miR-330-3p function in neuropathic pain remains largely incomplete. Here, we found that miR-330-3p was greatly increased in CCI rats and DGCR5 can modulate miR-330-3p expression negatively. Upregulation of DGCR5 repressed inflammation-correlated biomarkers including interleukin 6 (IL-6), tumor necrosis factor α, and IL-1ß in CCI rats by sponging miR-330-3p. The negative correlation between DGCR5 and miR-330-3p was confirmed in our current study. Inhibition of miR-330-3p suppressed neuropathic pain progression by restraining neuroinflammation in vivo. In addition, PDCD4 was predicted as a downstream target of miR-330-3p. Furthermore, PDCD4 was significantly increased in CCI rats and DGCR5 regulated PDCD4 expression through sponging miR-330-3p in CCI rat models. Taken these together, it was implied that DGCR5/miR-330-3p/PDCD4 axis participated in neuropathic pain treatment.

Genes associated with persistent lumbar radicular pain; a systematic review.

BACKGROUND: The aim of the present study was to provide an overview of the literature addressing the role of genetic factors and biomarkers predicting pain recovery in newly diagnosed lumbar radicular pain (LRP) patients. METHODS: The search was performed in Medline OVID, Embase, PsycInfo and Web of Science (2004 to 2015). Only prospective studies of patients with LRP addressing the role of genetic factors (genetic susceptibility) and pain biomarkers (proteins in serum) were included. Two independent reviewers extracted the data and assessed methodological quality. RESULTS: The search identified 880 citations of which 15 fulfilled the inclusion criteria. Five genetic variants; i.e., OPRM1 rs1799971 G allele, COMT rs4680 G allele, MMP1 rs1799750 2G allele, IL1α rs1800587 T allele, IL1RN rs2234677 A allele, were associated with reduced recovery of LRP. Three biomarkers; i.e., TNFα, IL6 and IFNα, were associated with persistent LRP. CONCLUSION: The present results indicate that several genetic factors and biomarkers may predict slow recovery in LRP. Still, there is a need for replication of the findings. A stricter use of nomenclature is also highly necessary. TRIAL REGISTRATION: The review is registered PROSPERO 20th of November 2015. Registration number is CRD42015029125 .

Inhibition of Mitochondrial Fission Protein Reduced Mechanical Allodynia and Suppressed Spinal Mitochondrial Superoxide Induced by Perineural Human Immunodeficiency Virus gp120 in Rats.

BACKGROUND: Mitochondria play an important role in many cellular and physiologic functions. Mitochondria are dynamic organelles, and their fusion and fission regulate cellular signaling, development, and mitochondrial homeostasis. The most common complaint of human immunodeficiency virus (HIV)-sensory neuropathy is pain on the soles in patients with HIV, but the exact molecular mechanisms of HIV neuropathic pain are not clear. In the present study, we investigated the role of mitochondrial dynamin-related protein 1 (Drp1, a GTPase that mediates mitochondrial fission) in the perineural HIV coat glycoprotein gp120-induced neuropathic pain state. METHODS: Neuropathic pain was induced by the application of recombinant HIV-1 envelope protein gp120 into the sciatic nerve. Mechanical threshold was tested using von Frey filaments. The mechanical threshold response was assessed over time using the area under curves. Intrathecal administration of antisense oligodeoxynucleotide (ODN) against Drp1, mitochondrial division inhibitor-1 (mdivi-1), or phenyl-N-tert-butylnitrone (a reactive oxygen species scavenger) was given. The expression of spinal Drp1 was examined using western blots. The expression of mitochondrial superoxide in the spinal dorsal horn was examined using MitoSox imaging. RESULTS: Intrathecal administration of either antisense ODN against Drp1 or mdivi-1 decreased mechanical allodynia (a sensation of pain evoked by nonpainful stimuli) in the gp120 model. Intrathecal ODN or mdivi-1 did not change basic mechanical threshold in sham surgery rats. Intrathecal Drp1 antisense ODN decreased the spinal expression of increased Drp1 protein induced by peripheral gp120 application. Intrathecal phenyl-N-tert-butylnitrone reduced mechanical allodynia. Furthermore, both intrathecal Drp1 antisense ODN and mdivi-1 reversed the upregulation of mitochondrial superoxide in the spinal dorsal horn in the gp120 neuropathic pain state. CONCLUSIONS: These data suggest that mitochondrial division plays a substantial role in the HIV gp120-related neuropathic pain state through mitochondrial reactive oxygen species and provides evidence for a novel approach to treating chronic pain in patients with HIV.

Schwann cell LRP1 regulates remak bundle ultrastructure and axonal interactions to prevent neuropathic pain.

Trophic support and myelination of axons by Schwann cells in the PNS are essential for normal nerve function. Herein, we show that deletion of the LDL receptor-related protein-1 (LRP1) gene in Schwann cells (scLRP1(-/-)) induces abnormalities in axon myelination and in ensheathment of axons by nonmyelinating Schwann cells in Remak bundles. These anatomical changes in the PNS were associated with mechanical allodynia, even in the absence of nerve injury. In response to crush injury, sciatic nerves in scLRP1(-/-) mice showed accelerated degeneration and Schwann cell death. Remyelinated axons were evident 20 d after crush injury in control mice, yet were largely absent in scLRP1(-/-) mice. In the partial nerve ligation model, scLRP1(-/-) mice demonstrated significantly increased and sustained mechanical allodynia and loss of motor function. Evidence for central sensitization in pain processing included increased p38MAPK activation and activation of microglia in the spinal cord. These studies identify LRP1 as an essential mediator of normal Schwann cell-axonal interactions and as a pivotal regulator of the Schwann cell response to PNS injury in vivo. Mice in which LRP1 is deficient in Schwann cells represent a model for studying how abnormalities in Schwann cell physiology may facilitate and sustain chronic pain.

Interleukin-17 contributes to neuroinflammation and neuropathic pain following peripheral nerve injury in mice.

UNLABELLED: Cytokines, essential mediators of inflammatory and immune responses, play an important role in the pathophysiological processes associated with neuropathic pain following peripheral nerve injury. Recently, a novel proinflammatory cytokine, the interleukin (IL)-17, was found to orchestrate inflammatory responses in a wide range of inflammatory and autoimmune diseases of the nervous system. Here, we investigated the role of IL-17 in mediating neuroinflammation and pain hypersensitivity using the neuropathic pain model of partial ligation of the sciatic nerve in mice. Compared to wild-type, IL-17 knockout (KO) mice displayed significantly decreased mechanical pain hypersensitivity as well as decreased infiltration of T cells and macrophages to the injured sciatic nerves and the L3-L5 dorsal root ganglia and decreased activation of microglia and astrocytes in the L3-5 dorsal and ventral horns of the spinal cord. Further, intraplantar and intraneural injection of recombinant IL-17 into the hind paw and the sciatic nerve, respectively, induced both mechanical allodynia and thermal hyperalgesia, whereas intrathecal injection produced thermal hyperalgesia. IL-17 administration was associated with a significant increase in the numbers of infiltrating neutrophils and activated dendritic cells in the injected hind paws and infiltrating neutrophils in the injected sciatic nerves. Taken together, our results demonstrate that IL-17 contributes to the regulation of immune cell infiltration and glial activation after peripheral nerve injury and the ensuing neuropathic pain. PERSPECTIVE: IL-17 is an important regulator of immune responses and is involved in inducing and mediating proinflammatory reactions. Using IL-17 KO mice, we have demonstrated that IL-17 contributes to neuroinflammatory responses and pain hypersensitivity following neuropathic injury. This work identifies IL-17 as a potential therapeutic target in neuropathic pain.

Intra-neural administration of fractalkine attenuates neuropathic pain-related behaviour.

There is increasing evidence that a number of cytokines and their receptors are involved in the processes that lead to the development and maintenance of neuropathic pain states. Here we demonstrate that levels of CX3CR1 (the receptor for the chemokine fractalkine) mRNA in lumbar dorsal root ganglia (DRG) increase 5.8-fold 7 days after sciatic nerve axotomy, and 1.7- and 2.9-fold, 3 and 7 days respectively, after the spared nerve injury (SNI) model of neuropathic pain. In contrast, no significant change in the levels of fractalkine mRNA is apparent in the DRG after axotomy or SNI. The increase in CX3CR1 mRNA is paralleled by a 3.9- and 2.1-fold increase in the number of CX3CR1-positive macrophages in the DRG 7 days after axotomy and SNI, respectively. Expression of CX3CR1 in macrophages is also markedly increased in the sciatic nerve proximal to site of injury, by 25.7-fold after axotomy and 16.2-fold after SNI, 7 days after injury. Intra-neural injection into the sciatic nerve of 400 ng or 100 ng of fractalkine in adult 129OlaHsd mice significantly delayed the development of allodynia for 3 days following SNI. Further, CX3CR1 knockout (KO) mice display an increase in allodynia for three weeks after SNI compared to strain-matched Balb/c controls. Taken together, these results suggest an anti-allodynic role for fractalkine and its receptor in the mouse.

Is the interleukin-6 haplotype a prognostic factor for sciatica?

AIMS: We have shown in a cross-sectional setting that an IL6 haplotype (GGGA) is associated with intervertebral disc disease (IDD) characterized by sciatica. The aim of this study was to evaluate the prognostic role of the GGGA haplotype in IDD. METHODS: DNA from 153 sciatica patients who participated in a randomized controlled trial of periradicular infiltration was analysed for IL6 variations rs1800797 (-596A>G), rs1800796 (-572G>C), rs1800795 (-174G>C), and rs13306435 (+15T>A). The patients recorded back and leg pain intensity and duration, disability by Oswestry Index and back-related sickness absence over a three-year follow-up. Repeated measures and univariate analysis of variance with adjustment for age, gender and physical work load were used in statistical analyses for the last two-years of the follow-up. RESULTS: The prevalence of the GGGA haplotype was 9% (14/153). Subjects with the GGGA haplotype did not differ from those without the haplotype with respect to pain intensity, or disability score, but days with back and leg pain and days on sick leave were significantly higher among subjects with the IL6 haplotype after adjustment for occupation (p=0.006, 0.001 and 0.002, respectively). An interaction between the IL6 haplotype and physical work load was significant for the duration of back and leg pain and sick leave (p=0.038, 0.011 and 0.006, respectively). CONCLUSIONS: This is the first observation of any prognostic genotype among sciatica patients. The IL6 haplotype GGGA predicted the number of days with back or leg pain and also sickness absence. Subjects with the IL6 haplotype may be more vulnerable when doing physically demanding jobs.

Dramatic etanercept-induced remission of relapsing febrile sciatic neuralgia related to p46l mutation of the tnfrsf1a gene.

An adult patient experienced attacks of severe low back pain and sciatic neuralgia for several years, sometimes associated with myalgias, skin lesions, and high fever. Specific inflammatory laboratory tests were the major abnormalities. P46L mutation in the gene on chromosome 12p13 that encodes tumor necrosis factor receptor superfamily 1A (TNFRSF1A) was found. Management with anti-TNF agent was effective with a complete remission of bouts of pain and fever.

A clinical genetic method to identify mechanisms by which pain causes depression and anxiety.

BACKGROUND: Pain patients are often depressed and anxious, and benefit less from psychotropic drugs than pain-free patients. We hypothesize that this partial resistance is due to the unique neurochemical contribution to mood by afferent pain projections through the spino-parabrachial-hypothalamic-amygdalar systems and their projections to other mood-mediating systems. New psychotropic drugs for pain patients might target molecules in such brain systems. We propose a method to prioritize molecular targets by studying polymorphic genes in cohorts of patients undergoing surgical procedures associated with a variable pain relief response. We seek molecules that show a significant statistical interaction between (1) the amount of surgical pain relief, and (2) the alleles of the gene, on depression and anxiety during the first postoperative year. RESULTS: We collected DNA from 280 patients with sciatica due to a lumbar disc herniation, 162 treated surgically and 118 non-surgically, who had been followed for 10 years in the Maine Lumbar Spine Study, a large, prospective, observational study. In patients whose pain was reduced >25% by surgery, symptoms of depression and anxiety, assessed with the SF-36 Mental Health Scale, improved briskly at the first postoperative measurement. In patients with little or no surgical pain reduction, mood scores stayed about the same on average. There was large inter-individual variability at each level of residual pain. Polymorphisms in three pre-specified pain-mood candidate genes, catechol-O-methyl transferase (COMT), serotonin transporter, and brain-derived neurotrophic factor (BDNF) were not associated with late postoperative mood or with a pain-gene interaction on mood. Although the sample size did not provide enough power to persuasively search through a larger number of genes, an exploratory survey of 25 other genes provides illustrations of pain-gene interactions on postoperative mood--the mu opioid receptor for short-term effects of acute sciatica on mood, and the galanin-2 receptor for effects of unrelieved post-discectomy pain on mood one year after surgery. CONCLUSION: Genomic analysis of longitudinal studies of pain, depression, and anxiety in patients undergoing pain-relieving surgery may help to identify molecules through which pain alters mood. Detection of alleles with modest-sized effects will require larger cohorts.

Genetic variations in IL6 associate with intervertebral disc disease characterized by sciatica.

Intervertebral disc disease (IDD) characterized by sciatica is a common disorder affecting about 5% of individuals. Environmental factors can predispose to this disease, but IDD has a strong genetic background. Recent evidence suggests that inflammation is one of the key factors in the etiology of IDD. Here, a possible role of the inflammatory mediator genes was studied in 155 patients with IDD-related sciatica and 179 controls. Forty-eight patients were analyzed for mutations in the IL1A, IL1B, IL6 and TNFA genes, and 16 polymorphisms in 10 candidate cytokine genes (IL1A, IL1B, IL1RN, TNFA, IL2, IL4, IL4R, IL6, IL10, IFNG) were genotyped from all subjects. No disease-causing mutations were identified in IL1A, IL1B, IL6 or TNFA. Allele frequencies were, however, significantly different between the two groups for IL6 SNP, T15A in exon 5 (P=0.007). Furthermore, the genotypes AA and AT of the exon 5 SNP were more common in the patients (P=0.011; OR=4.4, 95% CI=1.2-15.7; AR=7.5%, 1.6-13.1%). Haplotypes were then generated for four IL6 SNPs, G-597A, G-572C, G-174C, and T15A in exon 5. Haplotype GGGA was more common in the patients (P=0.011; OR=4.8, 95% CI=1.6-14.5). To evaluate attributable risk, haplotype pairs were assigned for the individuals. The presence of GGGA/GGGA or GGGA/other genotypes had an OR of 5.4 (95% CI=1.5-19.2). Association of GGGA with disease was highly significant (P=0.0033), and the associated AR was 6.8% (1.9-11.5%). These findings support the role of IL-6 genetic variations in discogenic pain.

Temporal expression of cytokines and their receptors mRNAs in a neuropathic pain model.

Proinflammatory mediators, such as tumor necrosis factor (TNF) alpha, interleukin (IL)-1beta and IL-6 have been found to play a key role in the propagation of persistent pain states. We investigated the temporal expressions of the mRNAs and the receptor mRNAs of TNFalpha, IL-1beta and IL-6 in rat dorsal root ganglia and spinal cord in a chronic constriction injury model of neuropathic pain. Our results show that the maximal induction of IL-6 mRNA occurred later and was more sustained than those of TNFalpha and IL-1beta mRNAs in the dorsal root ganglia and spinal cord following chronic injury. Receptors mRNAs, except TNF receptor 2 and gp130 mRNAs, showed temporal profiles that were similar to those of their cytokine mRNAs. Additionally, the induction of the mRNAs of cytokines and of their receptors in the dorsal root ganglia was more rapid than in the spinal cord.

Removal of a lumbar melanotic schwannoma via the far-lateral approach in a patient with Carney complex. Case report.

The authors describe a patient with Carney's complex who presented with sciatica due to a lumbar nerve root sheath tumor. A far-lateral approach was used to resect a nonpsammomatous melanotic schwannoma. Neurosurgeons surgically treating peripheral nerve sheath tumors should be aware of the features of Carney complex because the extent of the preoperative evaluation and postoperative management of an otherwise routine surgical condition can be significantly affected.

An allele of COL9A2 associated with intervertebral disc disease.

Intervertebral disc disease is one of the most common musculoskeletal disorders. A number of environmental and anthropometric risk factors may contribute to it, and recent reports have suggested the importance of genetic factors as well. The COL9A2 gene, which codes for one of the polypeptide chains of collagen IX that is expressed in the intervertebral disc, was screened for sequence variations in individuals with intervertebral disc disease. The analysis identified a putative disease-causing sequence variation that converted a codon for glutamine to one for tryptophan in six out of the 157 individuals but in none of 174 controls. The tryptophan allele cosegregated with the disease phenotype in the four families studied, giving a lod score (logarithm of odds ratio) for linkage of 4.5, and subsequent linkage disequilibrium analysis conditional on linkage gave an additional lod score of 7.1.