Pinjie Huang

Mast cells activation contribute to small intestinal ischemia reperfusion induced acute lung injury in rats

BACKGROUND Small intestinal ischemia-reperfusion (IIR) injury may lead to severe local and remote tissue injury, especially acute lung injury (ALI). Mast cell activation plays an important role in IIR injury. It is unknown whether IIR mediates lung injury via mast cell activation. METHODS Adult SD rats were randomized into sham operated group (S), sole IIR group (IIR) in which rats were subjected to 75 min of superior mesenteric artery occlusion followed by 4h reperfusion, or IIR being respectively treated with the mast cell stabilizer Cromolyn Sodium (IIR+CS group), with the tryptase antagonist Protamine (IIR+P group), with the histamine receptor antagonist Ketotifen (IIR+K group), or with the mast cell degranulator Compound 48/80 (IIR+CP group). The above agents were, respectively, administrated intravenously 5 min before reperfusion. At the end of experiment, lung tissue was obtained for histologic assessment and assays for protein expressions of tryptase and mast cell protease 7(MCP7). Pulmonary mast cell number and levels of histamine, TNF-α and IL-8 were quantified. RESULTS IIR resulted in lung injury evidenced as significant increases in lung histological scores (P<0.05 IIR vs. S), accompanied with concomitant increases of mast cell counts and elevations in TNF-α and IL-8 concentrations and reductions in histamine levels (all P<0.05 IIR vs. S). IIR also increased lung tissue tryptase and MCP7 protein expressions (all P<0.05, IIR vs. S). Cromolyn Sodium, Ketotifen and Protamine significantly reduced whilst Compound 48/80 aggravated IIR mediated ALI and the above biochemical changes (P<0.05). CONCLUSIONS Mast cells activation play a critical role in IIR mediated ALI.

Dexmedetomidine Inhibits TLR4/NF-κB Activation and Reduces Acute Kidney Injury after Orthotopic Autologous Liver Transplantation in Rats

Patients who undergo orthotopic liver transplantation often sustain acute kidney injury(AKI). The toll-like receptor 4(TLR4)/Nuclear factor-кB(NF-кB) pathway plays a role in AKI. Dexmedetomidine(Dex) has been shown to attenuate AKI. The current study aimed to determine whether liver transplantation-induced AKI is associated with inflammatory response, and to assess the effects of dexmedetomidine pretreatment on kidneys in rats following orthotopic autologous liver transplantation(OALT). Seventy-seven adult male rats were randomized into 11 groups. Kidney tissue histopathology and levels of blood urea nitrogen(BUN) and serum creatinine(SCr) were evaluated. Levels of TLR4, NF-κB, tumor necrosis factor-α, and interleukin-1β levels were measured in kidney tissues. OALT resulted in significant kidney functional impairment and tissue injury. Pre-treatment with dexmedetomidine decreased BUN and SCr levels and reduced kidney pathological injury, TLR4 expression, translocation of NF-κB, and cytokine production. The effects of dexmedetomidine were reversed by pre-treatment with atipamezole and BRL44408, but not ARC239. These results were confirmed by using α2A-adrenergic receptor siRNA which reversed the protective effect of dexmedetomidine on attenuating NRK-52E cells injury induced by hypoxia reoxygenation. In conclusion, Dexmedetomidine-pretreatment attenuates OALT-induced AKI in rats which may be contributable to its inhibition of TLR4/MyD88/NF-κB pathway activation. The renoprotective effects are related to α2A-adrenergic receptor subtypes.

The Mechanism of Sevoflurane Preconditioning-Induced Protections against Small Intestinal Ischemia Reperfusion Injury Is Independent of Mast Cell in Rats

The study aimed to investigate whether sevoflurane preconditioning can protect against small intestinal ischemia reperfusion (IIR) injury and to explore whether mast cell (MC) is involved in the protections provided by sevoflurane preconditioning. Sprague-Dawley rats exposed to sevoflurane or treated with MC stabilizer cromolyn sodium (CS) were subjected to 75-minute superior mesenteric artery occlusion followed by 2-hour reperfusion in the presence or absence of MC degranulator compound 48/80 (CP). Small intestinal ischemia reperfusion resulted in severe intestinal injury as demonstrated by significant elevations in intestinal injury scores and p47phox and gp91phox, ICAM-1 protein expressions and malondialdehyde and IL-6 contents, and MPO activities as well as significant reductions in SOD activities, accompanied with concomitant increases in mast cell degranulation evidenced by significant increases in MC counts, tryptase expression, and β-hexosaminidase concentrations, and those alterations were further upregulated in the presence of CP. Sevoflurane preconditioning dramatically attenuated the previous IIR-induced alterations except MC counts, tryptase, and β-hexosaminidase which were significantly reduced by CS treatment. Furthermore, CP exacerbated IIR injury was abrogated by CS but not by sevoflurane preconditioning. The data collectively indicate that sevoflurane preconditioning confers protections against IIR injury, and MC is not involved in the protective process.

Using inflammatory and oxidative biomarkers in urine to predict early acute kidney injury in patients undergoing liver transplantation

Abstract Objective: We examined the value of inflammatory and oxidative biomarkers in predicting acute kidney injury (AKI) following orthotopic liver transplantation (OLT). Methods: Urinary excretion of tumour necrosis factor-α (TNF-α), interleukin-8 (IL-8), interleukin-10 (IL-10), superoxide dismutase (SOD), malondialdehyde (MDA), 6-keto prostaglandin F1α (6-keto-PGF1α), hydrogen peroxide (H2O2), and 8-keto prostaglandin F2α (8-iso-PGF2α), serum creatinine (SCr), blood urea nitrogen (BUN), urinary N-acetyl-beta-D-glucosaminidase (NAG), β2-microglobulin (β2-MG) and γ-glutamyl-transferase (γ-GT), were measured before surgery (baseline), at 2 h after graft reperfusion and 24 h after OLT in 28 liver transplantation patients. Results: The levels of TNF-α, IL-8, IL-10, SOD, MDA, 6-keto-PGF1α, H2O2 and 8-iso-PGF2α in urine were all significantly higher in patients who had AKI than in those who did not at 2 h after graft reperfusion and 24 h after OLT (p < 0.01).

Dexmedetomidine improves gastrointestinal motility after laparoscopic resection of colorectal cancer: A randomized clinical trial.

Background:To investigate the effects of intraoperative application of dexmedetomidine (Dex) on early gastrointestinal motility after laparoscopic resection of colorectal cancer. Methods:In this prospective, randomized double-blind investigation, 60 patients who underwent laparoscopic resection of colorectal cancer were randomly allocated to receive Dex (DEX group, n = 30) or saline (CON group, n = 30). In the DEX group, Dex was loaded (1 &mgr;g/kg) before anesthesia induction and was infused (0.3 &mgr;g/kg/h) during surgery. Time to postoperative first flatus (FFL) and first feces (FFE), and time to regular diet were recorded. Serum diamine oxidase (DAO) activity and intestinal fatty acid-binding protein (I-FABP) were detected. Results:Both the time to the FFL (44.41 ± 4.51 hours vs 61.03 ± 5.16 hours, P = 0.02) and the time to the FFE (60.67 ± 4.94 hours vs 82.50 ± 6.88 hours, P = 0.014) were significantly shorter in the DEX group than the CON group. Furthermore, the time to regular diet of the DEX group was shorter than that of the CON group (76.15 ± 4.11 hours vs 91.50 ± 5.70 hours, P = 0.037). Both DAO and I-FABP increased significantly from beginning of surgery to postoperative day 1 in the CON group (2.49 ± 0.41 ng/mL vs 4.48 ± 0.94 ng/mL for DAO, P = 0.028, 1.32 ± 0.09 ng/mL vs 2.17 ± 0.12 ng/mL for I-FABP, P = 0.045, respectively), whereas no significant change was observed in the DEX group. Furthermore, patients in the DEX group had stable hemodynamics and shorter hospital stay than those in the CON group. Conclusion:Dex administration intraoperatively benefits recovery of gastrointestinal motility function after laparoscopic resection of colorectal cancer with stable hemodynamics during surgery though further studies are needed to explore the mechanisms of Dex on gastrointestinal motility.

Inhibiting tryptase after ischemia limits small intestinal ischemia-reperfusion injury through protease-activated receptor 2 in rats.

BACKGROUND Mast cell activation plays a key role in the process of small intestinal ischemia-reperfusion (IIR) injury; however, the precise role of tryptase released from mast cell on IIR injury remains poorly understood. The aim of this study was to determine the protective role against IIR injury by using tryptase inhibitor protamine after ischemia and to explore the underlying mechanism. METHODS Adult Sprague-Dawley rats were randomized into sham-operated group (S), sole IIR group (IIR) in which rats were subjected to 75-minute superior mesenteric artery occlusion followed by 4-hour reperfusion, or IIR being respectively treated with mast cell stabilizer cromolyn sodium (CS group), with the mast cell degranulator compound 48/80 (CP group), or with protamine (P group). The previously mentioned agents were, respectively, administered intravenously 5 minutes before reperfusion. The intestine tissue was obtained for histologic assessment and assays for protein expressions of tryptase and mast cell protease 7 and protease-activated receptor 2 (PAR-2). The intestine mast cell number and levels of tumor necrosis factor &kgr; and interleukin 8 were quantified. RESULTS IIR resulted in intestinal injury evidenced as significant increases in Chiu’s scores, accompanied with concomitant increases of mast cell counts and intestinal tryptase and mast cell protease 7 protein expressions. IIR also increased intestinal PAR-2 expressions, tumor necrosis factor &kgr;, and interleukin 8 levels. Cromolyn sodium and protamine significantly reduced the responses to IIR injury while compound 48/80 further aggravated the previously mentioned biochemical changes. CONCLUSION Tryptase releasing from mast cell activation participates in IIR injury through PAR-2, and inhibiting tryptase after ischemia provides promising benefits in limiting IIR injury.

Pivotal role of mast cell carboxypeptidase A in mediating protection against small intestinal ischemia-reperfusion injury in rats after ischemic preconditioning

AIM OF THE STUDY Mast cell (MC) degranulation contributes to the protection mediated by ischemic preconditioning (IPC); however, the precise mechanisms underlying this protection remain largely unknown. Mast cell carboxypeptidase A (MC-CPA) is released solely from MCs and plays a critical role in degrading toxins and endothelin 1 (ET-1). The present study sought to explore whether MC-CPA is involved in the process of IPC in a rodent model of small intestinal ischemia reperfusion (IIR) injury. MATERIALS AND METHODS IIR injuries were induced in Sprague-Dawley rats by clamping the superior mesenteric artery for 60 min followed by reperfusion for 2 h. One cycle of 10 min intestinal ischemia and 10 min of reperfusion was used in the IPC group, and the MC stabilizer cromolyn sodium and MC potato carboxypeptidase inhibitor were administered before the start of IPC. At the end of experiment, intestine tissue was obtained for assays of the MC-CPA3, tumor necrosis factor-α, interleukin-6, and ET-1 contents and myeloperoxidase activities. Intestinal histologic injury scores and MC degranulation were assessed. Apoptosis indices and cleaved caspase- 3 protein expressions were quantified. RESULTS IIR resulted in severe injury, as evidenced by significant increases in injury scores and MC-CPA3, tumor necrosis factor-α, interleukin-6, and ET-1 contents that were accompanied with concomitant elevations in cleaved caspase 3 expression, apoptosis indices, and myeloperoxidase activities. IPC induced a significant increase in MC-CPA3, induced MC degranulation, and attenuated IIR injury by downregulating IIR-induced biochemical changes, whereas cromolyn sodium and potato carboxypeptidase inhibitor abolished the IPC-mediated changes. CONCLUSIONS These data suggest that IPC protected against IIR injury via the MC degranulation-mediated release of MC-CPA.

Time-course analysis of counts and degranulation of mast cells during early intestinal ischemia-reperfusion injury in mice

Findings of previous studies have revealed that intestinal mucosal mast cells (IMMCs) are involved in small intestinal ischemia‑reperfusion injury (IIRI). However, time-course changes of mast cell counts and mast cell function in this process remain unclear. The present study aimed to observe the number of IMMCs and to investigate the correlation between their activation and small intestine injury at various time points during the period of small intestinal ischemia reperfusion (IIR). Healthy male Kunming mice were randomly divided into five groups, and were subjected to occlusion of the superior mesenteric artery (SMA) for 30 min and followed by reperfusion for 1, 3, 6 and 12 h. By contrast, the SMA was isolated but not clamped in the baseline group. Chius scores were assessed by light microscopy, tryptase protein and MCP7 protein expression in the intestine were quantified, and mast cell counts and levels of histamine and TNF-α in the intestine were measured. The results showed that IIR induced severe intestine injury within 12 h as demonstrated by Chius scores that was greatly increased as compared to the baseline group, accompanied by increased mast cell counts, histamine and TNF-α levels. However, the Chius scores were reduced in the IIR 12 h group compared with the IIR 1 h, IIR 3 h and IIR 6 h groups, with concomitant decreased mast cell counts, histamine and TNF-α levels. The tryptase and MCP7 protein expression was markedly increased in the IIR 1 h and IIR 3 h groups as compared with the baseline group, whereas this expression was gradually decreased at 6 and 12 h after reperfusion. The results of the present study suggest that IIR results in severe mucosal destruction within 6 h after reperfusion, associated with mast cell activation and substantial increases in the mast cell counts.

Effects of anti-histamine treatment on liver injury triggered by small intestinal ischemia reperfusion in rats.

Mast cell (MC) degranulation has been implicated in small intestinal ischemia reperfusion (IIR) injury, therein, inhibiting overproduction of histamine released from activated MC may provide promising strategies against IIR-mediated liver injuries. The aim of the present study was to explore whether anti-histamine treatment contribute to attenuating IIR-mediated liver injury. Adult SD rats were randomized into sham-operated group (S group), sole IIR group (IIR group), and IIR treated with Ketotifen, a histamine antagonist (IIR+K group), Cromolyn Sodium, a MC stabilizer (IIR+C group), and Compound 48/80, a MC degranulator (IIR+CP group), respectively. IIR was induced by superior mesenteric artery occlusion for 75 min followed by 4 h of reperfusion. The agents were intravenously administrated 5 min before reperfusion to induce different levels of histamine. Subsequently, serum concentrations of ALT, AST and histamine; levels of LDH,TNF-α, IL-8 and MDA as well as SOD activities in the liver were assessed. Histopathologic changes were also evaluated. IIR resulted in severe liver injury as demonstrated by significant increases in injury scores, with concomitant significant increases in serum ALT, AST and histamine levels, as well as LDH, TNF-α, IL-8, and MDA levels in the liver, accompanied by reduction in SOD activities (all P < 0.05, IIR vs. S). Treatments by Ketotifen and Cromolyn Sodium similarly markedly alleviated IIR-mediated liver injury as confirmed by significant reduction of the above biomedical changes whereas Compound 48/80 further aggravated IIR-mediated liver injury by dramatically enhancing the above biomedical changes. Data of our study suggest that anti-histamine treatments may provide promising benefits in alleviating liver injury triggered by IIR.

Intestinal mucosal injury induced by tryptase-activated protease-activated receptor 2 requires β-arrestin-2 in vitro

Tryptase exacerbates intestinal ischemia-reperfusion injury, however, the direct role of tryptase in intestinal mucosal injury and the underlying mechanism remains largely unknown. Protease-activated receptor 2 (PAR‑2), commonly activated by tryptase, interacts with various adaptor proteins, including β‑arrestin‑2. The present study aimed to determine whether tryptase is capable of inducing intestinal mucosal cell injury via PAR‑2 activation and to define the role of β‑arrestin‑2 in the process of injury. The IEC‑6 rat intestinal epithelial cell line was challenged by tryptase stimulation. Cell viability, lactate dehydrogenase (LDH) activity and apoptosis were analyzed to determine the severity of cell injury. Injury was also evaluated following treatments with specific PAR‑2 and extracellular signal‑related kinases (ERK) inhibitors, and knockdown of β‑arrestin‑2. PAR‑2, ERK and β‑arrestin‑2 protein expression levels were evaluated. Tryptase treatment (100 and 1,000 ng/ml) resulted in IEC‑6 cell injury, as demonstrated by significant reductions in cell viability, accompanied by concomitant increases in LDH activity and levels of cleaved caspase‑3 protein expression. Furthermore, tryptase treatment led to a marked increase in PAR‑2 and phosphorylated‑ERK expression, and exposure to specific PAR‑2 and ERK inhibitors eliminated the changes induced by tryptase. Knockdown of β‑arrestin‑2 blocked tryptase‑mediated cell injury, whereas tryptase exerted no influence on β‑arrestin‑2 expression in IEC‑6 cells. These data indicate that tryptase may directly damage IEC‑6 cells via PAR-2 and the downstream activation of ERK, and demonstrate that the signaling pathway requires β-arrestin-2.