Ryuji Kaku

The effects of epidural block on the distribution of lymphocyte subsets and natural-killer cell activity in patients with and without pain.

Although epidural anesthesia prevents immune suppression during surgery, no reports have elucidated how epidural block affects immune response in nonsurgical patients. We examined changes in proportion of lymphocyte subsets and in natural-killer (NK) cell activity in patients with and without pain. Fifteen patients with pain (Pain group) and 15 preoperative patients without pain (Preoperative group) received three different treatments in random order: epidural block with 7 mL 1% lidocaine, epidural injection of an identical volume of normal saline, and IV injection of 1 mg/kg lidocaine. Blood samples were drawn before and after 30, 60, and 120 min of treatment. During epidural block at 30 and 60 min, both groups showed significantly decreased epinephrine, norepinephrine, and cortisol levels, and the proportion of NK cells decreased, whereas the CD4+/CD8+ ratio increased significantly. NK cell activity in both groups decreased significantly at 30 and 60 min. At 120 min, the variables had all returned to preblock values. During treatments with saline and IV lidocaine, neither group showed significant changes in any of the above variables. We conclude that epidural block causes a transient and significant alteration of lymphocyte subsets and NK cell activity regardless of pain status.

Decoy strategy targeting the brain-derived neurotrophic factor exon I to attenuate tactile allodynia in the neuropathic pain model of rats.

The mechanism underlying neuropathic pain is still largely unclear. Recently, much attention has been focused on the role of brain-derived neurotrophic factor (BDNF) as a neuromodulator in the spinal cord. We previously reported that the expression of Bdnf exon I mRNA was remarkably up-regulated in the dorsal root ganglion (DRG) neurons with the rat L5 spinal nerve ligation (SNL) model. In the present study, we investigated whether neuropathic pain response would be reduced by the inhibition of the Bdnf exon I in the rat SNL model. We identified the promoter region of exon I and synthesized the decoy ODNs targeting the region. Reverse transcription-polymerase chain reaction analysis confirmed that the decoy ODN treatment reduced SNL-induced Bdnf exon I mRNA up-regulation in ipsilateral L4 and L5 DRGs. Furthermore, post-treatment with the decoy ODNs significantly attenuated SNL-induced tactile allodynia. This study suggested that decoy ODNs targeting the Bdnf exon I might provide a novel analgesic strategy for the treatment of neuropathic pain.

Expression changes of the neuregulin 1 isoforms in neuropathic pain model rats.

The neuregulin1 (Nrg1) gene that is expressed in the dorsal root ganglion (DRG) contains an EGF-like domain, which is known to be a direct ligand for ErbB3 and ErbB4. Multiple splice variants of the Nrg1 gene are broadly classified into 3 groups by structural features (type I, type II and type III) and their functions differ in various tissues. The Nrg1 gene has emerged as a key mediator of axon-Schwann cell interactions and as a regulator of Schwann cell development. The Nrg1 gene is indicated as a promising growth factor for neuronal development. However, the function of the Nrg1 in pain has not been clarified. We therefore, examined the expression profiles of each type of the Nrg1 transcript in the bilateral L4/L5 DRGs using L5 spinal nerve ligation (SNL) model rats and complete Freunds adjuvant (CFA) model rats. Behavior tests have shown typical mechanical hyperalgesia in both the L5SNL model and the CFA model. In the L5SNL model, expression of the Nrg1 type I and type II were significantly increased in the L5 DRG. On the other hand, the expression of the Nrg1 type III was decreased in the L5 DRG. We demonstrated that the expression changes of the Nrg1 isoforms in the ipsilateral DRGs were preferentially related to the response to nerve injury. Our findings suggest that the aberrant expression may play an important role in nerve injury, regeneration and subsequent neuropathic pain on the L5SNL.

Increased heme oxygenase-1 gene expression in the livers of patients with portal hypertension due to severe hepatic cirrhosis

Surgical bleeding associated with splanchnic hyperaemia due to portal hypertension complicates the anaesthetic management of hepatic transplantation. Although the mechanism(s) of portal hypertension are not fully understood, carbon monoxide, a product of the heme oxygenase (HO) reaction, is thought to be one of the endogenous vasodilators in the liver. In this study, the expression of mRNA encoding inducible HO isozyme (HO-1) in the livers of patients with portal hypertension undergoing hepatic transplantation was determined in comparison with those without portal hypertension. HO-1 mRNA levels were significantly greater in the portal hypertension group than in the group without portal hypertension. In contrast with HO-1, the gene expression of non-specific δ-aminolevulinate synthase (ALAS-N), which is down-regulated by heme in the liver, was the same in both groups. These results suggest that HO-1 is up-regulated through heme-independent stimuli according to the development of portal hypertension, and that induced HO-1 plays a pathophysiological role in portal hypertension through carbon monoxide production.

Altered response to formalin by L5 spinal nerve ligation in rats: a behavioral and molecular study.

BACKGROUND:The status of neuropathic pain alters the responsiveness to formalin injection in rats. However, the mechanism by which this alteration occurs is unknown. METHODS:We used immunocytochemistry to examine the expression of brain-derived neurotrophic factor (BDNF) and calcitonin gene-related peptide (CGRP) in the spinal cord of rats with L5 spinal nerve ligation (SNL)-induced neuropathy, and investigated the expression of c-Fos in the spinal cord after injection of formalin in the hindpaw of rats with SNL. RESULTS:Four weeks after SNL, the withdrawal threshold was significantly lower in the SNL group than in the sham-operated (sham) group (n = 12 per group, P < 0.05). In the SNL group, expression of BDNF in the L4 (P < 0.05) and L5 (P < 0.01) superficial dorsal horn was significantly decreased compared to that in the sham group. CGRP protein in the L5 but not in the L4, dorsal horn was significantly decreased compared to that in the sham group (P < 0.01). After formalin injection, spontaneous pain responses in the SNL group were significantly decreased compared to those in the sham group (P < 0.05). Immunolabeling for c-Fos was significantly decreased in the L4 and L5 dorsal horn in the SNL group (P < 0.01). CONCLUSION:Our examination of c-Fos distribution indicates that decreased neuronal activity in the spinal cord in response to inflammatory pain may be important for altering the perception of acute pain. Decreased BDNF expression in response to SNL-induced neuropathy may be involved in this alteration.

Up-regulation of brain-derived neurotrophic factor in the dorsal root ganglion of the rat bone cancer pain model

Metastatic bone cancer causes severe pain, but current treatments often provide insufficient pain relief. One of the reasons is that mechanisms underlying bone cancer pain are not solved completely. Our previous studies have shown that brain-derived neurotrophic factor (BDNF), known as a member of the neurotrophic family, is an important molecule in the pathological pain state in some pain models. We hypothesized that expression changes of BDNF may be one of the factors related to bone cancer pain; in this study, we investigated changes of BDNF expression in dorsal root ganglia in a rat bone cancer pain model. As we expected, BDNF mRNA (messenger ribonucleic acid) and protein were significantly increased in L3 dorsal root ganglia after intra-tibial inoculation of MRMT-1 rat breast cancer cells. Among the eleven splice-variants of BDNF mRNA, exon 1–9 variant increased predominantly. Interestingly, the up-regulation of BDNF is localized in small neurons (mostly nociceptive neurons) but not in medium or large neurons (non-nociceptive neurons). Further, expression of nerve growth factor (NGF), which is known as a specific promoter of BDNF exon 1–9 variant, was significantly increased in tibial bone marrow. Our findings suggest that BDNF is a key molecule in bone cancer pain, and NGF-BDNF cascade possibly develops bone cancer pain.

Extracellular-regulated-kinase 5-mediated renal protection against ischemia-reperfusion injury

ERK5, a member of the mitogen activated protein kinase, expressed in the kidneys was smaller (∼80kDa) in apparent molecular mass compared to other organs (∼120kDa). A blocking peptide experiment confirmed that the ∼80kDa detected on Western blots was a specific band detected by the anti-ERK5 antibody. Expression of the known ERK5 variants ERK5a, b, c, and T confirmed that none of the known splice variants encoded for the renal-specific ∼80kDa protein. However, RT-PCR with primers targeting the potential splice sites did not reveal a novel transcript in the kidney. The smaller molecular mass of the kidney-specific ERK5-immunoreactive protein suggested that this cyto-protective molecule may not be fully functional in the kidneys. Lentivirus-mediated in vivo overexpression of full length ERK5 in the mouse kidneys provided protection against renal IR injury. The identity of the renal-specific ∼80kDa ERK5 remains unknown but a better understanding of the ERK5 expression and post-translational processing in the kidneys may reveal a novel strategy for renal protection.

Spinal nerve injury causes upregulation of ErbB2 and ErbB3 receptors in rat dorsal root ganglia

It is generally known that peripheral nerve injury causes changes in expression of some growth factors in the dorsal root ganglion. Altered expression of ErbB receptors, a well-known growth factor in somatic cells, reportedly follows peripheral nerve injury in the spinal dorsal horn; however, it remains unknown whether the expression of these receptors is altered in the dorsal root ganglion after nerve injury. Therefore, this study examined the gene expression profiles of ErbB receptors in bilateral lumbar (L)4/L5 dorsal root ganglia, using L5-selective spinal nerve ligation in model rats as a peripheral nerve injury model. The expression of ErbB2 and ErbB3 was observed in the dorsal root ganglia of the mature rat, despite ErbB1 and ErbB4 showing only subtle expression. We also demonstrated that peripheral nerve injury induced significant increases in ErbB2 and ErbB3 in the ipsilateral dorsal root ganglion as compared with uninjured nerve. Expression changes in ErbB receptors appear to play important roles in nerve injury and subsequent nerve regeneration.

Heme breakdown and ischemia/reperfusion injury in grafted liver during living donor liver transplantation.

Living donor liver transplantation (LDLT) requires ischemia/reperfusion (I/R), which can cause early graft injury. However, the detailed mechanism of I/R injury remains unknown. Heme oxygenase-1 (HO-1) is a rate-limiting enzyme in heme catabolism and results in the production of iron, carbon monoxide (CO), and biliverdin IXα. Furthermore, in animals, HO-1 has a protective effect against oxidative stress associated with I/R injury. However, in humans, the molecular mechanism and clinical significance of HO-1 remain unclear. We previously demonstrated that exhaled CO levels increase during LDLT, and postulated that this may indicate I/R injury. In this study, we elucidate the origin of increased exhaled CO levels and the role of HO-1 in I/R injury during LDLT. We studied 29 LDLT donors and recipients each. For investigation of HO-1 gene expression by polymerase chain reaction and HO-1 localization by immunohistological staining, liver biopsies from the grafted liver were conducted twice, once before and once after I/R. Exhaled CO levels and HO-1 gene expression levels significantly increased after I/R. In addition, HO-1 levels significantly increased after I/R in Kupffer cells. Furthermore, we found a significant positive correlation between exhaled CO levels and HO-1 gene expression levels. These results indicated that increased heme breakdown in the grafted liver is the source of increased exhaled CO levels. We also found a significant relationship between HO-1 gene expression levels and alanine aminotransferase (ALT) levels; i.e., the higher the HO-1 gene expression levels, the higher the ALT levels. These results suggest that HO-1-mediated heme breakdown is caused by I/R during LDLT, since it is associated with increased exhaled CO levels and liver damage.

536: THE RELATIONSHIP BETWEEN SERUM ALBUMIN LEVEL AND ORGAN DYSFUNCTION AFTER LIVER TRANSPLANTATION

Critical Care Medicine • Volume 46 • Number 1 (Supplement) www.ccmjournal.org Learning Objectives: Some studies have shown that postoperative hypoalbuminemia following liver transplantation is associated with adverse events such as increased pleural fluids and ascites, acute kidney injury, longer ICU stay and death. Correction of postoperative hypoalbuminemia would prevent such postoperative complications; however, there is one question regarding what level of serum albumin to be maintained postoperatively. The present study investigated the relationship between postoperative albumin level and organ failure (assessed via the SOFA score), which has been the standard index for evaluating the severity of organ failure in ICU patients. Methods: This was a retrospective study of 60 patients admitted to the ICU after liver transplantation from 2013 to 2016. In our institution, the traditional procedure was to administer albumin to ameliorate ascites. The data collected included the patients’ pre-, intra-, and postoperative information during the first postoperative week. The study patients were divided into two groups: the higher albumin (HA) group (n = 33) and the lower albumin (LA) group (n = 27) according to serum albumin level > 3 g/dL during the first postoperative week. As the primary endpoint, the SOFA score was compared between the two groups. The secondary endpoints were complications (ascites amount, rejection, reintubation, abdominal re-operation, thrombosis), additional treatment (dialysis, pleural effusion drainage), and length of ICU stay. Results: No differences were found between groups in pre-and intraoperative data. The average serum albumin level in the HA group was higher than in the LA group (3.5 ± 0.25 vs. 3.1 ± 0.26 g/dL, P < 0.05); however, the amount of albumin infusion in the HA group was not larger than in the LA group during the first postoperative week (8188 ± 5009 vs. 7039 ± 4300 mL, P = 0.28). There were no significant differences in the mean daily SOFA scores between the HA and LA groups (7.9 ± 2.5 vs. 7.7 ± 2.0, P = 0.71). The HA group had a lower mean cardiovascular SOFA sub-score than the LA group (0.4 ± 0.6 vs. 0.9 ± 1.2, P < 0.05). There were no significant differences between groups in the complication rates, need for additional treatment, or length of ICU stay. Conclusions: The study results suggest that serum albumin level may not influence cumulative organ function (as measured by the SOFA score), but may preserve cardiovascular function in patients following liver transplantation.