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Background Acute glaucoma, characterized by a sudden elevation in intraocular pressure (IOP) and retinal ganglion cells (RGCs) death, is a major cause of irreversible blindness worldwide that lacks approved effective therapies, validated treatment targets and clear molecular mechanisms. We sought to explore the potential molecular mechanisms underlying the causal link between high IOP and glaucomatous RGCs death. Methods A murine retinal ischemia/ reperfusion (RIR) model and an in vitro oxygen and glucose deprivation/reoxygenation (OGDR) model were used to investigate the pathogenic mechanisms of acute glaucoma. Results Our findings reveal a novel mechanism of microglia-induced pyroptosis-mediated RGCs death associated with glaucomatous vision loss. Genetic deletion of gasdermin D (GSDMD), the effector of pyroptosis, markedly ameliorated the RGCs death and retinal tissue damage in acute glaucoma. Moreover, GSDMD cleavage of microglial cells was dependent on caspase-8 (CASP8)-hypoxia-inducible factor-1α (HIF-1α) signaling. Mechanistically, the newly identified nucleotide-binding leucine-rich repeat-containing receptor (NLR) family pyrin domain-containing 12 (NLRP12) collaborated with NLR family pyrin domain-containing 3 (NLRP3) and NLR family CARD domain-containing protein 4 (NLRC4) downstream of the CASP8-HIF-1α axis, to elicit pyroptotic processes and interleukin-1β (IL-1β) maturation through caspase-1 activation, facilitating pyroptosis and neuroinflammation in acute glaucoma. Interestingly, processing of IL-1β in turn magnified the CASP8-HIF-1α-NLRP12/NLRP3/NLRC4-pyroptosis circuit to accelerate inflammatory cascades. Conclusions These data not only indicate that the collaborative effects of NLRP12, NLRP3 and NLRC4 on pyroptosis are responsible for RGCs death, but also shed novel mechanistic insights into microglial pyroptosis, paving novel therapeutic avenues for the treatment of glaucoma-induced irreversible vision loss through simultaneously targeting of pyroptosis.

Purpose Dry eye disease (DED) is a common and multifactor-induced autoimmune ocular surface disease. Environmental factors, such as desiccating stress (DS) and hyperosmolarity, affect the corneal epithelium to induce ocular surface inflammation in DED. We aimed to explore the potential mechanisms by which innate immunity and pyroptosis are initiated in the mucosal epithelium in response to environmental stress. Methods Experimental dry eye was established in C57BL/6 J mice and genetic mice on the background of C57BL/6 J mice by subcutaneous injection of scopolamine and exposure to a desiccating environment. SDHCEC cell line was subjected to hyperosmolarity stress (450 mOsM). The phenol red thread tear test and corneal epithelial defects evaluation were used as assessments of severity of DED. RNA-sequencing, quantitative real-time PCR, western blotting and immunofluorescence staining were performed in this study. Results Loss-of-function studies indicated that genetic deletion of GSDMD alleviates DS-induced corneal epithelium defects, and GSDMD is needed for IL-33 processing. We further found that NLRP12 collaborates with NLRC4 inflammasome to initiate GSDMD-dependent pyroptosis, which requires TLR4-induced caspase-8 (CASP8) activation in the mucosal corneal epithelium in response to DS. Conclusions These findings provide compelling evidence that GSDMD-dependent pyroptosis plays a pivotal role in DED. A novel mechanism involving NLRP12 and NLRC4 inflammasomes-induced GSDMD-dependent pyroptosis, accompanied by IL-33 processing is responsible for ocular surface epithelial defects in response to environmental stress. GSDMD is required for IL-33 processing and the subsequent amplification of inflammatory cascades. These findings reveal novel therapeutic targets for treating DED.

Both oxidative stress and mast cell (MC) degranulation participate in the process of small intestinal ischemia reperfusion (IIR) injury, and oxidative stress induces MC degranulation. Propofol, an anesthetic with antioxidant property, can attenuate IIR injury. We postulated that propofol can protect against IIR injury by inhibiting oxidative stress subsequent from NADPH oxidase mediated MC activation. Cultured RBL-2H3 cells were pretreated with antioxidant N-acetylcysteine (NAC) or propofol and subjected to hydrogen peroxide (H2O2) stimulation without or with MC degranulator compound 48/80 (CP). H2O2 significantly increased cells degranulation, which was abolished by NAC or propofol. MC degranulation by CP further aggravated H2O2 induced cell degranulation of small intestinal epithelial cell, IEC-6 cells, stimulated by tryptase. Rats subjected to IIR showed significant increases in cellular injury and elevations of NADPH oxidase subunits p47(phox) and gp91(phox) protein expression, increases of the specific lipid peroxidation product 15-F2t-Isoprostane and interleukin-6, and reductions in superoxide dismutase activity with concomitant enhancements in tryptase and β-hexosaminidase. MC degranulation by CP further aggravated IIR injury. And all these changes were attenuated by NAC or propofol pretreatment, which also abrogated CP-mediated exacerbation of IIR injury. It is concluded that pretreatment of propofol confers protection against IIR injury by suppressing NADPH oxidase mediated MC activation.

Rebuilding of infarcted myocardium by mesenchymal stem cells (MSCs) has not been successful because of poor cell survival due in part to insufficient blood supply after myocardial infarction (MI). We hypothesize that targeted delivery of vascular endothelial growth factor (VEGF) to MI can help regenerate vasculature in support of MSC therapy in a rat model of MI. VEGF-encapsulated immunoliposomes targeting overexpressed P-selectin in MI tissue were infused by tail vein immediately after MI. One week later, MSCs were injected intramyocardially. The cardiac function loss was moderated slightly by targeted delivery of VEGF or MSC treatment. Targeted VEGF+MSC combination treatment showed highest attenuation in cardiac function loss. The combination treatment also increased blood vessel density (80%) and decreased collagen content in post-MI tissue (33%). Engraftment of MSCs in the combination treatment group was significantly increased and the engrafted cells contributed to the restoration of blood vessels. From the Clinical Editor VEGF immunoliposomes targeting myocardial infarction tissue resulted in significantly higher attenuation of cardiac function loss when used in combination with mesenchymal stem cells. MSCs were previously found to have poor ability to restore cardiac tissue, likely as a result of poor blood supply in the affected areas. This new method counterbalances that weakness by the known effects of VEGF, as demonstrated in a rat model.

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.

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.

Stabilizing mast cells (MCs) can either inhibit or augment inflammation; however, how improved therapeutic benefits against small intestinal ischemia-reperfusion injury (IIRI) can be achieved by stabilizing MCs remains to be elucidated. The present study was designed to evaluate different treatments with cromolyn sodium (CS, an MC stabilizer), which was administrated either prior to ischemia or after reperfusion. Kunming mice were randomized into a sham-operated group (SH), a sole IIR group (M), in which mice were subjected to 30 min superior mesenteric artery occlusion followed by 3 day or 3 h reperfusion, or IIR, treated with CS 15 min prior to ischemia or 15 min after reperfusion in the PreCr and PostCr groups. The survival rate and Chiu's scores were evaluated. The levels of ET-1, histamine, TNF-α and IL-6, and expression of MC protease 7 (MCP7), MC counts and myeloperoxidase (MPO) activity were quantified. IIR resulted in severe injury as demonstrated by significant increases in mortality and injury score. IIR also led to substantial elevations in the levels of ET-1, histamine, TNF-α and IL-6, expression of MCP7, MC counts and MPO activities (P0.05, M vs. SH groups). All biochemical changes were markedly reduced in the PostCr group (P0.05, PostCr vs. M groups), whereas pretreatment of IIR mice with CS prior to ischemia exhibited no changes of ET-1 levels, injury score and inflammation (P0.05, PreCr vs. M groups). In conclusion, administration of CS after reperfusion, but not prior to ischemia, attenuates IIRI by downregulating ET-1 and suppressing sustained MC activation.

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. Chiu's 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 Chiu's scores that was greatly increased as compared to the baseline group, accompanied by increased mast cell counts, histamine and TNF-α levels. However, the Chiu's 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.

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.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 κ and interleukin 8 were quantified.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 κ, 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.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.

Mast cell has been demonstrated to be involved in the small intestinal ischemia-reperfusion (IIR) injury, however, the precise role of tryptase released from mast cell on acute lung injury(ALI) induced by IIR remains to be elucidated, our study aimed to observe the roles of tryptase on ALI triggered by IIR and its underlying mechanism. Adult SD rats were randomized into sham-operated group, sole IIR group in which rats were subjected to 75 min superior mesenteric artery occlusion followed by 4 h reperfusion, or IIR being respectively treated with cromolyn sodium, protamine, and compound 48/80. The above agents were, respectively, administrated intravenously 5 min before reperfusion. At the end of experiment, lung tissue was obtained for assays for protein expressions of tryptase and mast cell protease 7 (MCP7) and protease-activated receptor 2 (PAR-2). Pulmonary mast cell number and levels of IL-8 were quantified. Lung histologic injury scores and lung water content were measured. IIR resulted in lung injury evidenced as significant increases in lung histological scores and lung water contents, accompanied with concomitant increases of expressions of tryptase and MCP7, and elevations in PAR-2 expressions and IL-8 levels in lungs. Stabilizing mast cell with cromolyn sodium and inhibiting tryptase with protamine significantly reduced IIR-mediated ALI and the above biochemical changes while activating mast cell with compound 48/80 further aggravated IIR-mediated ALI and the increases of above parameters. Tryptase released from mast cells mediates ALI induced by intestinal ischemia-reperfusion by activating PAR-2 to produce IL-8.

Propofol bolus injection has been reported to influence cardiovascular functions. However, the detailed mechanism underlying this action has not been elucidated. This study was designed to investigate the effects of propofol i.v. bolus on the left ventricular function, the myocardial β-adrenoceptor (β-AR) binding-site density (Bmax) and Kd (apparent dissociation constant) in a 30-minute period. One hundred and four male Wistar rats were randomly divided into four groups: group C (control group), group I (intralipid group), group P1 (5mg/kg propofol) and group P2 (10 mg/kg propofol). The results showed a significant downregulation of HR, LVSP, +dp/dt(subscript max) and -dp/dt(subscript max) in both groups P1 and P2 (especially after bolus injection in 7 min) than those of group C (P＜0.05), whereas no significant difference was found between the P1 and P2 groups (P＞0.05). Likely, Bmax was remarkably upregulated in both groups P1 and P2 (P＜0.05, vs. groups C and I), and there was no significant difference between these two groups (P＞0.05). Of note, the Kd value in group P2 (10 mg/kg propofol) was found dramatically increased in 30 min than that in the low-dose propofol-treated group (group P1) as well as in groups C and I (P＜0.05). In conclusion, these results indicate that intravenous injection of propofol bolus can inhibit the cardiac function partially via upregulation of Bmax and downregulation of the β-AR affinity at higher-dose injection of propofol bolus.

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 p47phoxand 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, andβ-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, andβ-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.

Liver abnormalities are seen in a small proportion of patients following anaesthesia with sevoflurane.To investigate whether the cytotoxicity of sevoflurane against rat liver cells was mediated by gap junction intercellular communications, and the effect of propofol on sevoflurane-induced cytotoxicity.Experimental study.The study was carried out in the central laboratory of The Third Affiliated Hospital, Sun Yat-sen University.BRL-3A rat liver cells.Immortal rat liver cells BRL-3A were grown at low and high density. Colony-forming assays were performed to determine clonogenic growth of these cells. To investigate the effect of oleamide and propofol on gap junction function, we measured fluorescence transmission between cells using parachute dye-coupling assays. Immunoblotting assays were performed to determine connexin32 and connexin43 expression.Our colony formation assays revealed that, in low-density culture, sevoflurane caused no apparent inhibition of clonogenic growth of BRL-3A cells. In high-density culture, 2.2 to 4.4% sevoflurane markedly inhibited clonogenic growth of BRL-3A cells with 67.6 (0.34)% and 61.2 (0.17)% of the cells being viable, respectively (P = 0.003 vs. low-density culture), suggesting cell density dependency of sevoflurane-induced cytotoxicity. Our colony formation assays revealed that propofol markedly attenuated the suppression by sevoflurane of the clonogenic growth of BRL-3A cells (viability: propofol and sevoflurane, 91.5 (0.014)% vs. sevoflurane, 56.6 (0.019)%; P 0.01). Blocking gap junctions with 10 μmol l oleamide significantly attenuated 4.4% sevoflurane-induced suppression with a viability of 83.6 ± 0.138% (oleamide and sevoflurane vs. sevoflurane, P 0.01). Immunoblotting assays further showed that propofol (3.2 μg ml) markedly reduced CX32 levels and significantly inhibited gap junctional intercellular communications as revealed by parachute dye-coupling assays. Values are mean (SD).This study provides the first direct evidence that sevoflurane-induced cytotoxicity, which is mediated through gap junctions, is attenuated by propofol, possibly by its action on Cx32 homomeric or heteromeric complexes.

Both oxidative stress and mast cells are involved in acute lung injuries (ALIs) that are induced by intestinal ischemia-reperfusion (IIR). The aim of this study was to further investigate the interaction between oxidative stress and mast cells during the process of IIR-induced ALI.Thirty adult Sprague-Dawley rats were randomly divided into five groups: sham, IIR, IIR + compound 48/80 (CP), N-acetylcysteine (NAC) + IIR, and NAC + IIR + CP. All rats except those in the sham group were subjected to 75 min of superior mesenteric artery occlusion, followed by 2 h of reperfusion. The rats in the NAC + IIR and NAC + IIR + CP groups were injected intraperitoneally with NAC (0.5 g/kg) for three successive days before undergoing IIR. The rats in the IIR + CP and NAC + IIR + CP groups were treated with CP (0.75 mg/kg), which was administered intravenously 5 min before the reperfusion. At the end of the experiment, lung tissue was obtained for pathologic and biochemical assays.IIR resulted in ALI, which was detected by elevated pathology scores, a higher lung wet-to-dry ratio, and decreased expression of prosurfactant protein C (P 0.05). Concomitant elevations were observed in the expression levels of the nicotinamide adenine dinucleotide phosphate oxidase subunits p47(phox) and gp91(phox) and the levels of hydrogen peroxide and malondialdehyde. However, superoxide dismutase activity in the lung was reduced (P 0.05). The level of interleukin 6, the activity of myeloperoxidase, and the expression of intercellular adhesion molecule 1 were also increased in the lung. IIR led to pulmonary mast cell degranulation and increases in the plasma and pulmonary β-hexosaminidase levels, mast cell counts, and tryptase expression in lung tissue. CP aggravated these conditions, altering the measurements further, whereas NAC attenuated the IIR-induced ALI and all biochemical changes (P 0.05). However, CP abolished some of the protective effects of NAC.Oxidative stress and mast cells interact with each other and promote IIR-induced ALI.

Background Activated mast cells are involved in the pathogenesis of intestinal ischemia–reperfusion (I/R)-related injury. Dexamethasone has been widely used to protect organs from I/R injury. This study was conducted to investigate the impact of treatment with dexamethasone at different stages of the II/R process on mast cell infiltration and activity and intestinal injury. Methods Kunming mice were randomized and subjected to a sham surgery or the II/R induction by clamping the superior mesenteric artery for 30 min and then reperfusion. During the II/R induction, the mice were treated intravenously with dexamethasone (10 mg/kg) for 30 min before ischemia (pretreatment group), at 5 min after clamping the superior mesenteric artery (isc-treatment group), or at the beginning of perfusion (rep-treatment group), respectively. The levels of intestinal injury, mast cell infiltration and activity, tumor necrosis factor α (TNFα) and myeloperoxidase (MPO) activity in the intestines, and mouse survival rates were measured. Results The death rates, levels of intestinal injury, mast cell infiltration and activity, and tumor necrosis factor α and myeloperoxidase activity in the intestinal tissues from the II/R group were similar to those from the isc-treatment and rep-treatment groups of mice and were significantly higher than those from the sham group. In contrast, pretreatment with dexamethasone significantly mitigated the II/R-induced mast cell infiltration and activity, inflammation, and intestinal injury and reduced the death rates in mice. Conclusions Pretreatment with dexamethasone inhibits II/R injury by reducing mast cell–related inflammation in mice.

Aim Histamine released from mast cell degranulation participates in the pathogenesis of ischemia/reperfusion injury. The purpose of our study was to define the role of histamine in hypoxia/reoxygenation mediated liver cell injury and to elucidate the underlying mechanism in vitro. Methods Histamine alone or in combination with H1 receptor antagonist (pyrilamine), H2 receptor antagonist (cimetidine) or H3/4 receptor antagonist (thioperamide) at different concentrations before hypoxia was added to rat liver BRL-3A cell which was subjected to 24 h hypoxia followed by 4 h reoxygenation. Cell proliferation, apoptosis and the changes of ultrastructure were assessed, and MDA contents, SOD activities and ALT levels were quantified as well. Results Histamine (from 10−3 to 10−9 M) did not affect the growth of BRL-3A cells without hypoxia treatment. However, histamine 10−8 M significantly lowered the growth of BRL-3A cells challenged by hypoxia/reoxygenation, accompanied with concomitant elevations in MDA contents and decreases in SOD activities, all these changes were blocked by cimetidine, not by pyrilamine or thioperamide. However, histamine (above 10−6 M) did not show exacerbating effects in BRL-3A cell subjected to hypoxia/reoxygenation. Conclusion Histamine at low concentrations (10−7–10−9 M) aggravates hypoxia/reoxygenation mediated BRL-3A damage through histamine H2 receptor.

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.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.IIR resulted in lung injury evidenced as significant increases in lung histological scores (P0.05 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 P0.05 IIR vs. S). IIR also increased lung tissue tryptase and MCP7 protein expressions (all P0.05, IIR vs. S). Cromolyn Sodium, Ketotifen and Protamine significantly reduced whilst Compound 48/80 aggravated IIR mediated ALI and the above biochemical changes (P0.05).Mast cells activation play a critical role in IIR mediated ALI.

AIM: To investigate the effects of Cromolyn Sodium (CS) pretreated prior to reperfusion on the activity of intestinal mucosal mast cells (IMMC) and mucous membrane of the small intestine in ischemia-reperfusion (IR) injury of rats. METHODS: Thirty-two Sprague-Dawley (SD) rats were randomly divided into four groups: sham group (group S), model group (group M), high and low dosage of CS groups, (treated with CS 50 mg/kg or 25 mg/kg, group C1 and C2). Intestinal IR damage was induced by clamping the superior mesenteric artery for 45 min followed by reperfusion for 60 min. CS was intravenouly administrated 15 min before reperfusion. Ultrastructure and counts of IMMC, intestinal structure, the expression of tryptase, levels of malondisldehyde (MDA), TNF-α, histamine and superoxide dismutase (SOD) activity of the small intestine were detected at the end of experiment. RESULTS: The degranulation of IMMC was seen in group M and was attenuated by CS treatment. Chiu’s score of group M was higher than the other groups. CS could attenuate the up-regulation of the Chiu’s score, the levels of MDA, TNF-α, and expression of tryptase and the down-regulation of SOD activity and histamine concentration. The Chiu’s score and MDA content were negatively correlated, while SOD activity was positively correlated to the histamine concentration respectively in the IR groups. CONCLUSION: Pretreated of CS prior to reperfusion protects the small intestine mucous from ischemia-reperfusion damage, the mechanism is inhibited IMMC from degranulation.