Biomedical subjects

Edwin A Deitch

Publications and source records attributed to Edwin A Deitch.

85 records · Page 5Linked to original sources

PubMed2002

Lipopolysaccharide-induced enterocyte-derived nitric oxide induces intestinal monolayer permeability in an autocrine fashion.

Studies indicate that endotoxin (LPS) causes intestinal injury, increases inducible nitric oxide synthase (iNOS) activity, leads to increased NO production, and promotes bacterial translocation (BT). To investigate the mechanism by which LPS causes gut injury and to test the hypothesis that NO produced by enterocytes promotes gut injury in an autocrine fashion, rat intestinal epithelial cell (IEC-6) monolayers were tested. IEC-6 monolayers grown in a bicameral system were incubated with media or with LPS (25 microg/mL) and tested for permeability to phenol red, BT, and nitrate/nitrite (NO2/NO3) production. To determine the direct effect of NO on permeability, monolayers were incubated with the NO donor S-nitroso-acetylpenicillinamide (SNAP; 1 mM) and tested for permeability. Next, the protective effects of two NOS inhibitors (L-NMMA and L-NIL) were tested. Finally, to determine if LPS-induced permeability occurs via a poly (ADP-ribose) synthetase- (PARS) dependent pathway, monolayers incubated with LPS alone or with the PARS inhibitor, INH2BP (100 microM) were tested. LPS significantly increased IEC-6 permeability to phenol red, as well as increased NO2/NO3 by 20-fold (P < 0.001) and increased BT 10-fold (P < 0.001). SNAP mimicked the effect of LPS and significantly increased both permeability to phenol red and BT. Inhibition of iNOS significantly decreased the LPS-induced increase in monolayer permeability and BT (P < 0.05). Monolayers incubated with INH2BP had significantly decreased permeability to phenol red and BT, suggesting that LPS-induced NO production increases monolayer permeability at least in part via a PARS-dependent mechanism. In summary, LPS-induced disruption of monolayer barrier function appears to be related, at least in part, to enterocyte produced NO. This supports the hypothesis that NO produced by LPS-stimulated enterocytes promotes injury in an autocrine fashion and highlights the fact that enterocytes can be a target as well as a producer of NO.

Animals↗

PubMed2002

Trauma/hemorrhagic shock mesenteric lymph upregulates adhesion molecule expression and IL-6 production in human umbilical vein endothelial cells.

Trauma/hemorrhagic shock (T/HS) is associated with significant lung injury, which is mainly due to an inflammatory process, resulting from the local activation and subsequent interaction of endothelial cells and leukocytes. Adhesion molecules expressed by both cell types play a crucial role in the process of neutrophil-mediated endothelial cell injury. We have previously shown that mesenteric lymph duct ligation prevents T/HS-induced lung leukocyte infiltration and endothelial injury, suggesting that inflammatory factors originating from the gut and carried in the lymph are responsible for the lung injury observed following T/HS. Based on these observations, we hypothesized that inflammatory substances in T/HS lymph trigger lung injury by a mechanism involving the upregulation of adhesion molecules. To test this hypothesis, we examined whether T/HS mesenteric lymph induces the expression of E-selectin, P-selectin, and intracellular adhesion molecule-1 (ICAM-1) in human umbilical vein endothelial cells (HUVECs). Furthermore, because the cytokine IL-6 is an important component of the endothelial inflammatory process, we investigated how T/HS lymph affects the production of IL-6 by HUVECs. Mesenteric lymph from T/HS rats increased both E- and P-selectin, as well as ICAM-1 expression on HUVECS, as compared to trauma/sham shock (T/SS) lymph or medium only groups. However, T/HS lymph failed to induce the shedding of E-selectin. In HUVECs treated with T/HS lymph, IL-6 concentrations were higher than HUVECs treated with T/SS lymph. These findings suggest that mesenteric lymph produced after hemorrhagic shock potentiates lung injury by the upregulation of endothelial cell adhesion molecule expression and IL-6 production.

Animals↗

PubMed2002

Hypertonic saline improves intestinal mucosa barrier function and lung injury after trauma-hemorrhagic shock.

Our objective was to test the hypotheses that small volume hypertonic saline (HTS) resuscitation protects against trauma-hemorrhagic shock (T/HS)-induced intestinal and lung injury better than standard volume resuscitation with Ringer's lactate (RL), and that the degree of lung injury correlates with the degree of gut injury after therapy. Male Sprague-Dawley rats were subjected to laparotomy (trauma) and 90 min of T/HS or sham shock (T/SS), and were then resuscitated with RL or 7.5% NaCl solution at an equivalent sodium load. Intestinal and lung injury was assessed at 3 and 24 h after resuscitation. Lung permeability, pulmonary myeloperoxidase (MPO) levels, and the bronchoalveolar lavage fluid (BALF) protein to plasma protein ratio were increased after T/HS, but were significantly lower in HTS-resuscitated than RL-treated rats. The incidence of bacterial translocation (BT) was not different between the groups, but the magnitude of BT after T/HS was less after HTS than RL resuscitation. Barrier function of intestinal segments was impaired only in the T/HS rats resuscitated with RL and histological analysis demonstrated fewer injured villi in the T/HS rats resuscitated with HTS than RL. Linear regression analysis revealed direct correlations between the percent of injured villi, increased lung permeability, and pulmonary neutrophil sequestration. Resuscitation with HTS ameliorated T/HS-induced gut and lung injury seen with RL resuscitation. These results, together with the direct correlation found between gut and lung injury, suggest that lung injury after T/HS may be mediated by gut injury.

Animals↗

PubMed2002

Attenuated monocyte IL-10 production in glucose-6-phosphate dehydrogenase-deficient trauma patients.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the world's most common known human genetic polymorphisms, but the pathophysiology of the defect remains largely unknown. In the present study, we compared hematology parameters and ex vivo monocyte cytokine responses in non-deficient and G6PD-deficient trauma patients. Deficient and non-deficient, moderately injured, trauma patients exhibited similar hematology profiles at the time of hospital admission. In contrast to non-deficient patients, G6PD-deficient patients were anemic 2 days post-injury. Monocytes from deficient individuals produced 50% less interleukin 10 (IL-10) in response to LPS and >90% less IL-10 in response to PMA, compared with non-deficient patients, 2 days post-injury. The presence of phenylhydrazine-treated, opsonized, autologous RBC (OX-RBC), alone had no effect on IL-10 production by non-deficient or deficient monocytes, whereas IL-10 responses to lipopolysaccharide (LPS) were augmented by OX-RBC in both groups. However, IL-10 production was markedly lower by monocytes from G6PD-deficient than non-deficient patients after stimulation with LPS plus OX-RBC. TNF-alpha production following PMA was similar in deficient and non-deficient patients, and the differences following LPS or LPS plus OX-RBC stimulation were moderate between deficient and non-deficient samples. Interferon (IFN)-gamma production ex vivo was doubled by OX-RBC treatment alone, but it was not stimulated by LPS treatment. IFN-gamma production was similar in non-deficient and G6PD-deficient patients. These data suggest that the observed differences in IL-10 responses between G6PD-deficient and non-deficient patients are not attributable to differences in TNF-alpha or IFN-gamma production. Taken together, our data suggest that a reduction in the capacity to produce IL-10 may be an intrinsic characteristic of G6PD-deficient monocytes. An attenuated IL-10 production may be a contributing mechanism in the previously observed augmented inflammatory response in severely injured G6PD-deficient compared with non-deficient trauma patients.

Adult↗

PubMed2002

Burn-induced impairment of cardiac contractile function is due to gut-derived factors transported in mesenteric lymph.

Neither the source nor the cause of burn-induced myocardial dysfunction is known. Because scald burns have been shown to cause cardiac contractile dysfunction, the purpose of this study was to test the hypothesis that gut-derived myocardial depressant factors were responsible for burn-induced cardiac contractile dysfunction. Male rats were subjected to laparotomy with or without mesenteric lymph duct ligation (LDL). After LDL or sham-LDL, the rats were randomized to receive sham or scald burn (43% TBSA full thickness) after which they were resuscitated for 24 h with 4 mL/kg/%burn of Ringers lactate solution, and then killed, and the hearts removed. Cardiac function was assessed by measuring the left ventricular pressure (LVP) and maximal rate of LVP rise and fall (+/-dP/dt) in response to increases either in 1) preload, 2) coronary flow rate, or 3) perfusate calcium. At 24 h after burn or sham burn and before killing, the mean arterial pressure of the burn group was less than the burn + LDL or the sham burn groups (P < 0.05). Pre-burn LDL significantly prevented burn-induced depression in LVP and +/-dP/dt (P < 0.05). In addition, the hearts harvested from the burn group showed a significant impairment in contraction and relaxation when preload, coronary flow, or perfusate calcium was increased compared with the burn + LDL and sham groups (P < 0.05). Burn-induced cardiac dysfunction, manifested by impaired contraction and relaxation, is prevented by pre-burn lymph duct ligation. These results indicate that gut-derived myocardial depressant factors transported in mesenteric lymph contribute to burn-induced impairment of cardiac contractile function, because burn-induced cardiac dysfunction can be totally abrogated by pre-burn mesenteric lymph duct ligation.

Animals↗

PubMed2002

Trauma-hemorrhage-induced neutrophil priming is prevented by mesenteric lymph duct ligation.

Our objective in this study was to test the hypothesis that priming of neutrophils (PMN) in vivo by trauma-hemorrhagic shock (T/HS) is mediated by factors carried in intestinal lymph that prime PMNs by enhancing their responses to inflammatory mediators. Previous studies have shown that T/HS-induced lung injury is mediated by factors contained in mesenteric lymph and that ligation of the main mesenteric lymph duct (LDL) can prevent T/HS-induced lung injury. Since T/HS-induced lung injury is associated with PMN infiltration, one mechanism underlying this protective effect may be the prevention of PMN priming and activation. Therefore, we assessed the ability of T/HS to prime PMN responses to inflammatory agonists, and the ability of mesenteric lymph duct division to protect against such T/HS-induced PMN priming in an all-rat system. PMN were collected from male rats 6 h after laparotomy (trauma) plus hemorrhagic shock (30 mmHg for 90 min; T/HS) or trauma plus sham shock (T/SS). Uninstrumented rats were used as controls (UC). In a second set of experiments, rats were subjected to T/HS with or without mesenteric lymph duct division. PMN were then stimulated with chemokine (GRO, MIP-2) and lipid (PAF) chemoattractants, and cell calcium flux was used to quantify responses to those agonists. T/SS primed PMN responses to GRO, MIP-2. and PAF in comparison to UC rats, but the addition of shock (T/HS) amplified PMN priming in a significant manner, especially in response to GRO. Mesenteric lymph duct division prior to T/HS diminished PMN priming to the levels seen in T/SS. This reversal of priming was significant for GRO and GRO/MIP-2 given sequentially, with the other agonist regimens showing similar trends. The results support the concept that trauma and hemorrhagic shock play important additive roles in inflammatory PMN priming. Entry of gut-derived inflammatory products into the circulation via mesenteric lymph seems to play a dominant role in mediating the conversion of physiologic shock insults into immunoinflammatory PMN priming. Shock-induced gut lymph priming enhances PMN responses to many important chemoattractants, most notably the chemokines, and mesenteric lymph duct division effectively reverses such priming to priming levels seen in trauma without shock.

Animals↗

PubMed2002

Inhibitors of ATP-binding cassette transporters suppress interleukin-12 p40 production and major histocompatibility complex II up-regulation in macrophages.

ATP-binding cassette (ABC) transporters are a large family of proteins whose role is to translocate various substances across biological membranes. They include the Tangier disease protein ABC1, sulfonylurea receptors (SUR), multidrug resistance protein (MDR), and cystic fibrosis transmembrane regulator (CFTR). In the current study, we investigated the involvement of ABC transporters in the regulation of lipopolysaccharide (LPS) and/or interferon (IFN)-gamma-induced interleukin (IL)-12 p40 and tumor necrosis factor (TNF)-alpha production, nitric oxide formation, as well as major histocompatibility complex II up-regulation in macrophages. The general ABC transporter inhibitor glibenclamide suppressed both IL-12 p40 and nitric oxide production. However, glibenclamide failed to affect the production of TNF-alpha. The selective ABC1 inhibitors 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and sulfobromophthalein mimicked the suppressive effect of glibenclamide on IL-12 p40 production. On the other hand, both the MDR inhibitor verapamil and CFTR blocker 2,2'-iminodibenzoic acid failed to suppress the production of IL-12 p40. Furthermore, selective inhibitors and activators of SURs were without effect. In agreement with the pharmacological data, macrophages expressed mRNA for ABC1, but not SURs or CFTR. Intracellular levels of IL-12 p40 were decreased by glibenclamide, suggesting that glibenclamide does not affect IL-12 p40 secretion. The effect of glibenclamide did not involve an interference with the activation of the p38 and p42/44 mitogen-activated protein kinases or c-Jun kinase. Glibenclamide also suppressed IFN-gamma-induced up-regulation of major histocompatibility complex II. Taken together, our results indicate that ABC proteins regulate LPS and/or IFN-gamma-induced macrophage activation.

ATP-Binding Cassette Transporters↗

PubMed2002

NHE blockade inhibits chemokine production and NF-kappaB activation in immunostimulated endothelial cells.

Na(+)/H(+) exchanger (NHE) activation has been documented to contribute to endothelial cell injury caused by inflammatory states. However, the role of NHEs in regulation of the endothelial cell inflammatory response has not been investigated. The present study tested the hypothesis that NHEs contribute to endothelial cell inflammation induced by endotoxin or interleukin (IL)-1beta. NHE inhibition using amiloride, 5-(N-ethyl-N-isopropyl)-amiloride, and 5-(N-methyl-N-isobutyl)amiloride as well as the non-amiloride NHE inhibitors cimetidine, clonidine, and harmaline suppressed endotoxin-induced IL-8 and monocyte chemoattractant protein (MCP)-1 production by human umbilical endothelial vein cells (HUVECs). The suppressive effect of amiloride on endotoxin-induced IL-8 production was associated with a decreased accumulation of IL-8 mRNA. NHE inhibitors suppressed both inhibitory (I)kappaB degradation and nuclear factor (NF)-kappaB DNA binding, suggesting that a decrease in activation of the IkappaB-NF-kappaB system contributed to the suppression of HUVEC inflammatory response by NHE blockade. NHE inhibition decreased also the IL-1beta-induced HUVEC inflammatory response, because amiloride suppressed IL-1beta-induced E-selectin expression on HUVECs. These results demonstrate that maximal activation of the HUVEC inflammatory response requires a functional NHE.

Adjuvants, Immunologic↗

PubMed2002

Na+/H+ exchanger blockade inhibits enterocyte inflammatory response and protects against colitis.

Na+/H+ exchangers (NHEs) are integral transmembrane proteins found in all mammalian cells. There is substantial evidence indicating that NHEs regulate inflammatory processes. Because intestinal epithelial cells express a variety of NHEs, we tested the possibility that NHEs are also involved in regulation of the epithelial cell inflammatory response. In addition, since the epithelial inflammatory response is an important contributor to mucosal inflammation in inflammatory bowel disease (IBD), we examined the role of NHEs in the modulation of disease activity in a mouse model of IBD. In human gut epithelial cells, NHE inhibition using a variety of agents, including amiloride, 5-(N-methyl-N-isobutyl)amiloride, 5-(N-ethyl-N-isopropyl)- amiloride, harmaline, clonidine, and cimetidine, suppressed interleukin-8 (IL-8) production. The inhibitory effect of NHE inhibition on IL-8 was associated with a decrease in IL-8 mRNA accumulation. NHE inhibition suppressed both activation of the p42/p44 mitogen-activated protein kinase and nuclear factor-kappaB. Finally, NHE inhibition ameliorated the course of IBD in dextran sulfate-treated mice. Our data demonstrate that inhibition of NHEs may be an approach worthy of pursuing for the treatment of IBD.

Amiloride↗

PubMed2002

Poly(ADP-ribose) polymerase is a regulator of chemokine production: relevance for the pathogenesis of shock and inflammation.

BACKGROUND: Chemokines are key regulators of leukocyte traffic in various forms of inflammation and reperfusion injury. There is emerging evidence that the activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) importantly contributes to the up-regulation of a variety of proinflammatory signal transduction pathways and associated genes. MATERIALS AND METHODS: We tested whether the expression of the chemokines macrophage inflammatory protein (MIP)-1alpha and MIP-2 are under the control of PARP during inflammation. RESULTS: Pharmacologic inhibition of PARP and genetic deletion of PARP suppressed the expression of MIP-1a and MIP-2 protein and mRNA in immunostimulated cultured murine macrophages and fibroblasts. PARP inhibition also suppressed the activation of NF-kappaB, a key transcription factor known to be involved in the generation of chemokines in immunostimulated cells. In vivo, in various models of local and systemic inflammation, including dextran sodium sulfate-induced colitis and endotoxic shock, pharmacologic inhibition of PARP suppressed the expression of MIP-1alpha and MIP-2. These effects were associated with a marked suppression of the inflammatory response, including an attenuation of neutrophil infiltration into inflamed organs. CONCLUSIONS: A combination approach of pharmacologic inhibition and genetic deletion revealed that the major isoform of PARP (PARP-1) plays a predominant, but not exclusive, role in the regulation of chemokine production in vivo. Suppression of chemokine expression may be a novel mode of anti-inflammatory action of PARP inhibition.

Animals↗

PubMed2001

Lithium induces NF-kappa B activation and interleukin-8 production in human intestinal epithelial cells.

Lithium has been documented to regulate apoptosis and apoptotic gene expression via NF-kappa B and mitogen-activated protein (MAP) kinase-dependent mechanisms. Since both NF-kappa B and MAP kinases are also important mediators of inflammatory gene expression, we investigated the effect of lithium on NF-kappa B- and MAP kinase-mediated inflammatory gene expression. Incubation of human intestinal epithelial cells with lithium induced both enhanced NF-kappa B DNA binding and NF-kappa B-dependent transcriptional activity. In addition, lithium stimulated activation of both the p38 and p42/44 MAP kinases. This lithium-induced up-regulation of NF-kappa B and MAP kinase activation was associated with an enhancement of interleukin-8 mRNA accumulation as well as an increase in interleukin-8 protein release. These proinflammatory effects of lithium were, in large part, mediated by activation of Na(+)/H(+) exchangers, because selective blockade of Na(+)/H(+) exchangers prevented the lithium-induced intestinal cell inflammatory response. These results demonstrate that lithium stimulates inflammatory gene expression via NF-kappa B and MAP kinase activation.

Adrenergic alpha-Agonists↗

PubMedDate not supplied

Inducible nitric oxide synthase knockout mice are resistant to diet-induced loss of gut barrier function and intestinal injury.

Loss of gut barrier function has been documented to occur in animals receiving total parenteral nutrition (TPN) and certain liquid diets. However, the mechanisms responsible for diet-induced gut barrier dysfunction remain to be fully determined. Thus we tested the hypothesis that increased intestinal nitric oxide production contributes to this phenomenon. To test this hypothesis, iNOS-deficient (iNOS -/-) mice and their wild-type littermates (iNOS +/+) were fed either chow or TPN solution for 14 days. Subsequently they were killed and gut barrier function was assessed by measuring bacterial translocation to the mesenteric lymph node (MLN) complex. Additionally, intestinal bacterial population levels, gut morphology, plasma and intestinal nitric oxide levels, as well as intestinal levels of the nitric oxide synthase (NOS) enzymes cNOS and iNOS, were measured. Bacterial translocation occurred in the iNOS +/+ but not the iNOS -/- mice receiving oral TPN solution. Oral TPN-induced bacterial translocation was associated with increased intestinal bacterial population levels as well as morphologic evidence of intestinal injury. Plasma and intestinal levels of the nitric oxide products, nitrite/nitrate, were increased in the iNOS +/+ mice fed the TPN solution but not in the chow-fed groups or the iNOS -/- mice receiving TPN solution. Last, intestinal iNOS, but not cNOS, activity was increased in the iNOS +/+ oral TPN-fed mice. These results implicate a role for increased intestinal nitric oxide production, through iNOS, in the pathogenesis of oral TPN-induced gut barrier dysfunction and injury.

Animals↗

PubMedDate not supplied

Burns, bacterial translocation, gut barrier function, and failure.

The development of systemic inflammation, acute lung injury, and multiple organ failure after a major thermal injury, as well as nonthermal forms of trauma, remain relatively common causes of morbidity and mortality. During the past two decades, increasing recognition that the ischemic gut may contribute to the development of sepsis and organ failure in burn patients, as well as other critically ill patient populations, has led to new hypotheses to explain burn-induced multiple organ failure as well as highlighted the importance of early enteral nutrition. Thus, the goal of this review will be to provide a perspective on the evolution of the gut hypothesis of systemic inflammation and distant organ dysfunction.

Bacterial Translocation↗