Xiao-Min Wang

Genetically mediated interindividual variation in analgesic responses to cyclooxygenase inhibitory drugs.

Wide interindividual variation in responses to cyclooxygenase (COX) inhibitory drugs limits their clinical utility and safety.

Upregulation of IL-6, IL-8 and CCL2 gene expression after acute inflammation: Correlation to clinical pain

ABSTRACT Tissue injury initiates a cascade of inflammatory mediators and hyperalgesic substances including prostaglandins, cytokines and chemokines. Using microarray and qRT‐PCR gene expression analyses, the present study evaluated changes in gene expression of a cascade of cytokines following acute inflammation and the correlation between the changes in the gene expression level and pain intensity in the oral surgery model of tissue injury and acute pain. Tissue injury resulted in a significant upregulation in the gene expression of interleukin‐6 (IL‐6; 63.3‐fold), IL‐8 (8.1‐fold), chemokine (C‐C motif) ligand 2 (CCL2; 8.9‐fold), chemokine (C‐X‐C motif) ligand 1 (CXCL1; 30.5‐fold), chemokine (C‐X‐C motif) ligand 2 (CXCL2; 26‐fold) and annexin A1 (ANXA1; 12‐fold). The upregulation of IL‐6 gene expression was significantly correlated to the upregulation of IL‐8, CCL2, CXCL1 and CXCL2 gene expression. Interestingly, the tissue injury‐induced upregulation of IL‐6, IL‐8 and CCL2 gene expression, was positively correlated to pain intensity at 3 h post‐surgery, the onset of acute inflammatory pain. However, ketorolac treatment did not have a significant effect on the gene expression of IL‐6, IL‐8, CCL2, CXCL2 and ANXA1 at the same time point of acute inflammation. These results demonstrate that the upregulation of IL‐6, IL‐8 and CCL2 gene expression contributes to the development of acute inflammation and inflammatory pain. The lack of effect of ketorolac on the expression of these gene products may be related to the ceiling analgesic effects of non‐steroidal anti‐inflammatory drugs.

Rofecoxib modulates multiple gene expression pathways in a clinical model of acute inflammatory pain

Abstract New insights into the biological properties of cyclooxygenase‐2 (COX‐2) and its response pathway challenge the hypothesis that COX‐2 is simply pro‐inflammatory and inhibition of COX‐2 solely prevents the development of inflammation and ameliorates inflammatory pain. The present study performed a comprehensive analysis of gene/protein expression induced by a selective inhibitor of COX‐2, rofecoxib, compared with a non‐selective COX inhibitor, ibuprofen, and placebo in a clinical model of acute inflammatory pain (the surgical extraction of impacted third molars) using microarray analysis followed by quantitative RT‐PCR verification and Western blotting. Inhibition of COX‐2 modulated gene expression related to inflammation and pain, the arachidonic acid pathway, apoptosis/angiogenesis, cell adhesion and signal transduction. Compared to placebo, rofecoxib treatment increased the gene expression of ANXA3 (annexin 3), SOD2 (superoxide dismutase 2), SOCS3 (suppressor of cytokine signaling 3) and IL1RN (IL1 receptor antagonist) which are associated with inhibition of phospholipase A2 and suppression of cytokine signaling cascades, respectively. Both rofecoxib and ibuprofen treatment increased the gene expression of the pro‐inflammatory mediators, IL6 and CCL2 (chemokine C‐C motif ligand 2), following tissue injury compared to the placebo treatment. These results indicate a complex role for COX‐2 in the inflammatory cascade in addition to the well‐characterized COX‐dependent pathway, as multiple pathways are also involved in rofecoxib‐induced anti‐inflammatory and analgesic effects at the gene expression level. These findings may also suggest an alternative hypothesis for the adverse effects attributed to selective inhibition of COX‐2.

Upregulation of α-synuclein during localized radiation therapy signals the association of cancer-related fatigue with the activation of inflammatory and neuroprotective pathways

PURPOSE Neuroinflammatory mechanisms are associated with fatigue in neurodegenerative conditions such as Parkinsons. The symptoms in Parkinsons including fatigue are thought to be related to α-synuclein overexpression. This study investigated genomic correlates of fatigue experienced by men with prostate cancer receiving external beam radiation therapy (EBRT). PATIENTS AND METHODS Sixteen men with non-metastatic prostate cancer who were scheduled to receive EBRT were enrolled. Fatigue scores and blood were obtained at baseline (prior to EBRT, D0); one hour following initiation of EBRT (D1), day 7 (D7), day 14 (D14), midpoint (days 19-21, D21), completion (days 38-42, D42), and four weeks post-EBRT (days 68-72, D72). Gene expression profiling using microarray analysis was performed from peripheral blood and confirmatory qPCR and protein (ELISA) analyses verified the microarray results. Correlations between fatigue and gene/protein expressions were determined using a mixed model approach. RESULTS Microarray data showed significant, differential expression of 463 probesets following EBRT. SNCA had a 2.95-fold change at D21 from baseline. SNCA expression was confirmed by qPCR (p<0.001) and ELISA (p<0.001) over time during EBRT. Fatigue scores were significantly correlated with SNCA gene expression on D14 (r=0.55, p<0.05) and plasma α-synuclein concentrations on D42 of EBRT (r=0.54, p=0.04). CONCLUSION Fatigue experienced during EBRT may be mediated by α-synuclein overexpression. Alpha-synuclein may serve as a useful biomarker to understand the mechanisms and pathways related to the development of fatigue in this population.

Rofecoxib regulates the expression of genes related to the matrix metalloproteinase pathway in humans: implication for the adverse effects of cyclooxygenase-2 inhibitors.

Cyclooxygenase‐2 (COX‐2) and COX‐2–derived prostaglandins contribute to acute inflammation and pain, as well as resolution of inflammation; inhibition of COX‐2 results in persistence of inflammation. Because matrix metalloproteinases (MMPs) play an essential role in inflammatory tissue injury and their activity is regulated by COX‐2–derived prostaglandin E2, we evaluated whether COX‐2 inhibition is associated with MMP overexpression during acute inflammation.

Nitric oxide is negatively correlated to pain during acute inflammation.

BackgroundThe role that nitric oxide (NO) plays in modulating pain in the periphery is unclear. We show here, the results of two independent clinical studies (microdialysis and gene expression studies) and a pilot dose finding study (glyceryl trinitrate study), to study the role of NO in the early phase of acute inflammatory pain following oral surgery. The effect of ketorolac on NO production and nitric oxide synthase (NOS) gene expression was also studied.ResultsMicrodialysis samples showed significantly higher levels of NO at the first 100 min compared to the last 80 minutes in the placebo treated group. In the ketorolac group, on the other hand, NO levels gradually decreased over the first 60 min but were similar to placebo over the later 100-180 min, with no significant change in NO level over time. The levels of NO were negatively correlated to pain intensity scores. Local infusion of the NO donor glyceryl trinitrate at the site of surgery, showed a small analgesic effect that did not reach statistical significance in the sample size used. While the gene expression of iNOS and eNOS were not up-regulated, 3 hours after surgery, nNOS was downregulated in both treatment groups and eNOS gene expression was significantly lower in the ketorolac group compared to the placebo group. Further, there was a positive correlation between the change in gene expression of nNOS and eNOS in the placebo goup but not in the ketorolac group.ConclusionWe suggest that at this early stage of inflammatory pain in man, NO is analgesic in the periphery. Further, ketorolac down-regulates eNOS gene expression.

Kinin B1 receptors contributes to acute pain following minor surgery in humans

BackgroundKinins play an important role in regulation of pain and hyperalgesia after tissue injury and inflammation by activating two types of G-protein-coupled receptors, the kinin B1 and B2 receptors. It is generally accepted that the B2 receptor is constitutively expressed, whereas the B1 receptor is induced in response to inflammation. However, little is known about the regulatory effects of kinin receptors on the onset of acute inflammation and inflammatory pain in humans. The present study investigated the changes in gene expression of kinin receptors and the levels of their endogenous ligands at an early time point following tissue injury and their relation to clinical pain, as well as the effect of COX-inhibition on their expression levels.ResultsTissue injury resulted in a significant up-regulation in the gene expression of B1 and B2 receptors at 3 hours post-surgery, the onset of acute inflammatory pain. Interestingly, the up-regulation in the gene expression of B1 and B2 receptors was positively correlated to pain intensity only after ketorolac treatment, signifying an interaction between prostaglandins and kinins in the inflammatory pain process. Further, the gene expression of both B1 and B2 receptors were correlated. Following tissue injury, B1 ligands des-Arg9-BK and des-Arg10-KD were significantly lower at the third hour compared to the first 2 hours in both the placebo and the ketorolac treatment groups but did not differ significantly between groups. Tissue injury also resulted in the down-regulation of TRPV1 gene expression at 3 hours post-surgery with no significant effect by ketorolac treatment. Interestingly, the change in gene expression of TRPV1 was correlated to the change in gene expression of B1 receptor but not B2 receptor.ConclusionsThese results provide evidence at the transcriptional level in a clinical model of tissue injury that up-regulation of kinin receptors are involved in the development of the early phase of inflammation and inflammatory pain. The up-regulation of B1 receptors may contribute to acute inflammatory pain through TRPV1 activation.

COX inhibitors downregulate PDE4D expression in a clinical model of inflammatory pain.

Tumor necrosis factor‐α (TNF‐α) has a central role in inflammation and is modulated by prostaglandin E2 (PGE2) and cyclic adenosine monophosphate (cAMP). Using microarray, quantitative real‐time polymerase chain reaction (qRT‐PCR), and protein detection techniques, we showed that ketorolac and rofecoxib had no significant effect on TNF‐α gene expression in oral mucosal biopsies 3 h after surgery. They both, however, downregulated the gene and protein expression of phosphodiesterase type 4 (PDE4D), which might represent a novel mechanism contributing to their analgesic and anti‐inflammatory effects.

Genomic Methods for Clinical and Translational Pain Research

Pain is a complex sensory experience for which the molecular mechanisms are yet to be fully elucidated. Individual differences in pain sensitivity are mediated by a complex network of multiple gene polymorphisms, physiological and psychological processes, and environmental factors. Here, we present the methods for applying unbiased molecular-genetic approaches, genome-wide association study (GWAS), and global gene expression analysis, to help better understand the molecular basis of pain sensitivity in humans and variable responses to analgesic drugs.

PIII-4Gene expression of chemokines and complement component following inflammation and rofecoxib treatment in a clinical model of tissue injury

The regulation of the complement pathway by chemokines plays a key role in inflammation and pain. The study evaluated gene expression related to chemokines and complement components in a clinical model of inflammation and pain initiated by tissue injury, and following treatment by a selective or non‐selective COX‐2 inhibitor.