Jiin-Tarng Liou

Inflammation Confers Dual Effects on Nociceptive Processing in Chronic Neuropathic Pain Model

Background:Although inflammation induces pain, immune cells also produce mediators that can effectively counteract it. To further elucidate the role of the immune response, we analyzed the relationship of pain behavior, several inflammatory signals, and opioid peptides using partial sciatic nerve ligation in mice at different levels of immunocompromise. Methods:Sciatic nerves of C57BL/6C, nonobese diabetic (NOD), or nonobese diabetic–severe combined immune deficiency (NOD-SCID) mice were partially ligated. Responses to mechanical and radiant heat stimuli were observed. Inflammation was detected by immunohistochemistry and flow cytometry. Inflammatory cytokines and opioid peptides were analyzed using real-time polymerase chain reaction and enzyme-linked immunosorbent assay or immunostaining. Results:Inflammation in immunocompromised mice was subordinate when compared with that seen in C57BL/6C mice. In addition, immunocompromised mice had less pain hypersensitivity at early stages. Whereas proinflammatory tumor necrosis factor-&agr; (TNF-&agr;), interleukin 1&bgr; (IL-1&bgr;), interleukin 6 (IL-6), and interferon-&ggr; (IFN-&ggr;), as well as antiinflammatory interleukin 1 receptor antagonist (IL-1Ra), interleukin 4 (IL-4), interleukin 10 (IL-10), and interleukin 13 (IL-13) cytokine expression and protein were increased in C57BL/6C mice, they were lower in immunocompromised mice. Although enkephalin, dynorphin, and &bgr;-endorphin messenger RNA expression also increased in C57BL/6C mice, peaking on day 14, this result was not observed in immunocompromised mice. Conclusion:The contribution of inflammation to nerve injury is complex with biphasic modulation. During the early phase, a wide range of proinflammatory cytokines are released, leading to enhanced pain. In contrast, the analgesic effect of opioid peptides and antiinflammatory cytokines was more predominate in the later phases of injury, leading to attenuated pain responses.

Inhibition of the cyclic adenosine monophosphate pathway attenuates neuropathic pain and reduces phosphorylation of cyclic adenosine monophosphate response element-binding in the spinal cord after partial sciatic nerve ligation in rats

BACKGROUND:Recent reports have identified a role for cyclic adenosine monophosphate (cAMP) transduction in nociceptive processing. Spinal activation of the cAMP induced gene transcription through the activation of protein kinase A and cAMP response element-binding protein (CREB). Intrathecal injection of protein kinase A inhibitor reversed the mechanical hyperalgesia, whereas injection of CREB antisense attenuated tactile allodynia caused by partial sciatic nerve ligation (PSNL) in rats. In the present study, we aimed to assess the effects of spinal cAMP transduction on the nociceptive processing in a chronic neuropathic pain model. METHODS:PSNL was performed in male Sprague-Dawley rats 1 wk after intrathecal catheterization. Nociception to mechanical and thermal stimuli was assessed at the hindpaw 2 h, 3, 7, and 14 days after PSNL. The effects of adenylate cyclase inhibitor, SQ22536 (0.7 &mgr;mol, intrathecal) on these nociceptions were evaluated. Changes in the expression and immunoreactivity of CREB and its phosphorylated proteins (CREB-IR and pCREB-IR) in the dorsal horn of the spinal cord were also measured. RESULTS:The expression of CREB-IR and pCREB-IR proteins was shown to increase for 2 wk after PSNL. The increase in pCREB was partially reversed by the blockade of the cAMP pathway in the early 3 days, with a parallel increase in mechanical and thermal withdrawal thresholds. CONCLUSION:These results revealed the possible contribution of an increase in pCREB to the PSNL-induced tactile allodynia and thermal hyperalgesia. Modulation of the cAMP pathway may be clinically relevant if early intervention can be achieved in patients with chronic neuropathic pain.

Sirtinol attenuates hepatic injury and pro-inflammatory cytokine production following trauma-hemorrhage in male Sprague-Dawley rats.

Background: Although studies have demonstrated that sirtinol administration following adverse circulatory conditions is known to be protective, the mechanism by which sirtinol produces the salutary effects remains unknown. We hypothesized that sirtinol administration in male rats following trauma‐hemorrhage decreases cytokine production and protects against hepatic injury.

Hydroxyethyl starch interferes with human blood ex vivo coagulation, platelet function and sedimentation.

BACKGROUND Hydroxyethyl starch (HES) solutions are widely used for intravascular volume expansion. In Taiwan, the medium molecular weight of HES 200/0.5 and HES 130/0.4 solutions are most commonly used. It has been demonstrated that HES may affect coagulation and platelet function significantly. However, the differential effects of each medium molecular weight HES on platelets remain poorly reported. Therefore, we studied the influence of the two HES solutions on platelet function in vitro by mixing whole blood with different proportions of HES 130 kD, HES 200 kD, and saline to determine the differences. METHODS Human blood samples for platelet function analyzer (PFA), aggregometry and blood/HES mixed test were drawn from the antecubital vein and put into test tubes containing 3.2% trisodium citrate (blood:citrate, 9:1). The specimens were divided into four groups, designated as whole blood, 10%, 20%, and 30% dilution with normal saline (N/S), HES130 or HES200 solution. The platelet function of each sample was measured by both PFA and platelet aggregometry. RESULTS The results showed that the PFA-100 closure times CEPI-CT and CADP-CT were significantly prolonged in the samples diluted with normal saline, HES130 and HES200 than in the controls. The ADP triggered whole blood aggregometry showed that attenuated impedance was observed in samples of 20% diluted with HES130 and HES200 groups. The blood/HES mixed sedimentation test showed significantly increased proportion of the upper liquid layer in the HES200 group than in other groups. CONCLUSION Our data demonstrated that HES200 and HES130 possess noticeably inhibitory effects on platelet function, especially when the HES replaced proportion was more than 20%. HES200 has a greater effect on blood cells and plasma separation than does HES130.

Exogenous granulocyte colony-stimulating factor exacerbate pain-related behaviors after peripheral nerve injury

Previous studies have demonstrated that inflammatory cells produce several mediators that can effectively counteract pain. This study was designed to test the hypothesis that exogenous administration of recombinant mouse granulocyte-colony-stimulating factor (rmG-CSF) to enhance the recruitment of inflammatory cells to painful inflamed sites could attenuate pain in a chronic neuropathic pain model in mice. Our results indicate that treatment with rmG-CSF increased several cytokines and opioid peptides content; however, it did not attenuate but exacerbate neuropathic pain. Our study highlights the potent pro-inflammatory potential of G-CSF and suggests they may be targets for therapeutic intervention in chronic neuropathic pain.

Hemeoxygenase-1 Upregulation Is Critical for Sirtinol-mediated Attenuation of Lung Injury After Trauma-hemorrhage in a Rodent Model

BACKGROUND: Hemeoxygenase-1 induction in response to adverse circulatory conditions is protective. Our recent study has shown that administration of sirtinol attenuates hepatic injury in male Sprague-Dawley rats after trauma-hemorrhage; however, the mechanism by which sirtinol produces the salutary effects remains unknown. We hypothesized that sirtinol administration in male Sprague-Dawley rats after trauma-hemorrhage decreases cytokine production and protects against lung injury through a hemeoxygenase-1 related pathway. METHODS: Male Sprague-Dawley rats (n = 8 per group) underwent trauma-hemorrhage (mean arterial blood pressure 40 mm Hg for 90 min, then resuscitation). A single dose of sirtinol (1 mg/kg of body weight) with or without a hemeoxygenase enzyme inhibitor (chromium-mesoporphyrin) or vehicle was administered IV during resuscitation. Twenty-four hours thereafter, myeloperoxidase activity (a marker of neutrophil sequestration) and tumor necrosis factor &agr;, interleukin-6, and interleukin-10 levels in the lung, protein concentrations in bronchoalveolar lavage fluid and tissue histology were measured. Lung hemeoxygenase-1 protein level was also determined. RESULTS: In the sirtinol-treated rats subjected to trauma-hemorrhage, there were significant improvements in lung myeloperoxidase activity (4.68 ± 0.31 vs 9.36 ± 1.03 U/mg protein, P < 0.05), tumor necrosis factor &agr; levels (710.7 ± 28 vs 1288 ± 40.69 pg/mg protein, P < 0.05), interleukin-6 levels (343.6 ± 18.41 vs 592.7 ± 22.3 pg/mg protein, P < 0.05), and protein concentrations (303.8 ± 24.54 vs 569.6 ± 34.82 &mgr;g/mL, P < 0.05) and lesser damage in histology. There was no statistically significant difference in interleukin-10 levels in the lung between sirtinol-treated trauma-hemorrhaged rats and vehicle-treated trauma-hemorrhaged rats (842.5 ± 54.18 vs 756.2 ± 41.34 pg/mg protein, respectively). Lung hemeoxygenase-1 protein levels were increased in rats receiving sirtinol treatment as compared with vehicle-treated trauma-hemorrhaged rats (5.18 ± 0.25 vs 2.70 ± 0.16, P < 0.05). Administration of the hemeoxygenase inhibitor chromium-mesoporphyrin prevented the sirtinol-induced attenuation of shock-induced lung damage. CONCLUSION: The salutary effects of sirtinol administration on attenuation of lung inflammation after trauma-hemorrhage are mediated via upregulation of hemeoxygenase-1 expression.

lack of interleukin-17 leads to a modulated micro-environment and amelioration of mechanical hypersensitivity after peripheral nerve injury in mice

Summary Lack of interleukin‐17 leads to a modulated micro‐environment and amelioration of mechanical hypersensitivity after peripheral nerve injury in mice. ABSTRACT Interleukin‐17 (IL‐17) is involved in a wide range of inflammatory disorders and in recruitment of inflammatory cells to injury sites. A recent study of IL‐17 knock‐out mice revealed that IL‐17 contributes to neuroinflammation and neuropathic pain after peripheral nerve injury. Surprisingly, little is known of micro‐environment modulation by IL‐17 in injured sites and in pathologically related neuroinflammation and chronic neuropathic pain. Therefore, we investigated nociceptive sensitization, immune cell infiltration, myeloperoxidase (MPO) activity, and expression of multiple cytokines and opioid peptides in damaged nerves of wild‐type (IL‐17+/+) and IL‐17 knock‐out (IL‐17−/−) mice after partial sciatic nerve ligation. Our results demonstrated that the IL‐17−/− mice had less behavioral hypersensitivity after partial sciatic nerve ligation, and inflammatory cell infiltration and pro‐inflammatory cytokine (tumor necrosis factor–&agr;, IL‐6, and interferon‐&ggr;) levels in damaged nerves were significantly decreased, with the levels of anti‐inflammatory cytokines IL‐10 and IL‐13, and expressions of enkephalin, &bgr;‐endorphin, and dynorphin were also decreased compared to those in wild‐type control mice. In conclusion, we provided evidence that IL‐17 modulates the micro‐environment at the level of the peripheral injured nerve site and regulates progression of behavioral hypersensitivity in a murine chronic neuropathic pain model. The attenuated behavioral hypersensitivity in IL‐17−/− mice could be a result of decreased inflammatory cell infiltration to the injured site, resulting in modulation of the pro‐ and anti‐inflammatory cytokine milieu within the injured nerve. Therefore, IL‐17 may be a critical component for neuropathic pain pathogenesis and a novel target for therapeutic intervention for this and other chronic pain states.

P-selectin is required for neutrophils and macrophage infiltration into injured site and contributes to generation of behavioral hypersensitivity following peripheral nerve injury in mice.

Summary P‐selectin is required for neutrophils and macrophage infiltration into injured site and contributes to generation of behavioral hypersensitivity in a murine model of neuropathic pain. Abstract Growing evidence suggests that leukocyte extravasation is initiated by the interaction of selectins with their ligands; as well as an essential role for P‐selectin in the initial recruitment of inflammatory cells to sites of inflammation. In this study, P‐selectin‐deficient (P‐sel−/−) mice were used to test the hypothesis that lack of P‐selectin would attenuate the recruitment of inflammatory cells to the site of inflammation, thereby modulating pain in a murine chronic neuropathic pain model. Nociceptive sensitization and the microenvironment of the peripheral injury site were studied in wild‐type (P‐sel+/+) and P‐selectin‐deficient (P‐sel−/−) mice after partial sciatic nerve ligation (PSNL). Variables measured included myeloperoxidase (MPO) activity, several inflammatory cell infiltration profiles, cytokines, and endogenous opioid peptide expression in damaged nerves. Results indicate that behavioral hypersensitivity, MPO activity, and infiltration of neutrophils and macrophages were attenuated in P‐sel−/− mice after PSNL. Proinflammatory cytokines, tumor necrosis factor &agr;, and interleukin (IL)‐6, were reduced in damaged nerves following PSNL; however, several antiinflammatory cytokines – IL‐1Ra, IL‐4, and IL‐10 – were significantly increased in P‐sel−/− mice. In addition, endogenous opioid peptides mRNA was significantly lower in P‐sel−/− mice compared with P‐sel +/+ mice. The current results demonstrated that the absence of P‐selectin in mice leads to an altered microenvironment that attenuated behavioral hypersensitivity. The specific role of P‐selectin could have been a result of decreased neutrophils, as well as the accumulation of macrophages at the site of injury, which may subsequently modulate the inflammatory cytokine expression and impact behavioral hypersensitivity within the injured nerve.

A new insight of anti-platelet effects of sirtinol in platelets aggregation via cyclic AMP phosphodiesterase

Sirtinol, a cell permeable six-membered lactone ring, is derived from naphthol and potent inhibitor of SIR2 and its naphtholic may have the inhibitory effects on platelets aggregation. In this study, platelet function was examined by collagen/epinephrine (CEPI) and collagen/ADP-induced closure times using the PFA-100 system reveal that CEPI-CT and CADP-CT were prolonged by sirtinol. The platelets aggregation regulated by physiological agonists such as: thrombin, collagen and AA and U46619 were significantly inhibited by sirtinol. Increases cAMP level was observed when sirtinol treated with Prostaglandin E1 in washed platelets. Moreover, sirtinol attenuated intracellular Ca(2+) release and thromboxane B2 formation stimulated by thrombin, collagen, AA and U46619 in human washed platelets. This study indicated that sirtinol could inhibit the platelet aggregation induced by physiological agonists, AA and U46619. The mechanism of action may include an increase of cAMP level with enhanced VASP-Ser157 phosphorylation via inhibition of cAMP phosphodiesterase activity and subsequent inhibition of intracellular Ca(2+) mobilization, thromboxane A2 formation, and ATP release during the platelet aggregation.

Chemical Burn Caused by Providone-iodine Alcohol Solution-A Case Report

Burns associated with chemical disinfectants for skin preparation are rare. Skin irritation and maceration associated with pressure factors may contribute to its occurrence. We report a 24-year-old female with thyroid tumor who was admitted for subtotal thyroidectomy. After anesthetic induction, the patient was placed in the supine position with the trunk elevated to 20 degree. The skin over the anterior neck was sterilized with 10% Povidone-iodine (PI) alcohol solution. After a 3-hour surgery, the patient complained of burning pain over the back at the recovery room. Physical examination revealed a 9 x 11 cm area of skin lesion partially thickened amid on the middle of the back suggestive of chemical burn. After conservative treatment, she was discharged uneventfully 4 days later. Upon follow-up, the wound was seen to heal with minimal scarring within 3 weeks.