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Biomedical subjects

J G Norman

Publications and source records attributed to J G Norman.

At least 19 recordsLinked to original sources
PubMed1997

Cytokine activation through sublethal hemorrhage is protective against early lethal endotoxic challenge.

OBJECTIVES: To determine the immunologic consequences of nonlethal hemorrhage on subsequent exposure to lipopolysaccharide (LPS) and to determine the role of interleukin 1 beta (IL-1) specifically in mediating the response to LPS with and without prior hemorrhage. DESIGN: Prospective, randomized, controlled experimental trial. PARTICIPANTS: Male BALB/c mice and transgenic mice deficient in IL-1 converting enzyme. INTERVENTIONS: Animals were subjected to hemorrhage (by cardiac puncture), LPS challenge by intraperitoneal injection, or hemorrhage followed 24 hours later by LPS challenge. Mortality was assessed every 4 hours for 96 hours following hemorrhage or LPS exposure. Serum IL-1 levels were determined 24 hours after exposure to hemorrhage and LPS. SETTING: University of South Florida Core General Surgery Research Facility, Tampa. MAIN OUTCOME MEASURES: Mortality and serum IL-1 levels. RESULTS: Hemorrhage alone resulted in complete survival, whereas LPS alone resulted in near-complete (95%) mortality. Hemorrhage, when given 24 hours before LPS challenge, afforded significant protection compared with LPS alone (67% survival vs 5% survival; P < .001). Serum IL-1 levels 24 hours after exposure to LPS were significantly lower in prehemorrhaged mice than in those receiving LPS alone. Transgenic mice incapable of producing biologically active IL-1 were further protected, demonstrating near-complete (95%) survival following hemorrhage and LPS challenge. CONCLUSIONS: Cytokine activation through nonlethal hemorrhage attenuates subsequent IL-1 response to early immunologic challenge. Such immune suppression appears to be protective early on and is supported by the near-complete immunity to LPS in animals incapable of producing biologically active IL-1.

Animals↗
PubMed1997

Matrix metalloproteinase inhibition attenuates human pancreatic cancer growth in vitro and decreases mortality and tumorigenesis in vivo.

Matrix metalloproteinases (MMP) are enzymes responsible for extracellular matrix degradation, a critical component influencing the growth and metastatic potential of cancer. The purpose of this study was to determine the in vitro effects of MMP inhibition on human pancreatic cancer cells and to document its effect on cancer growth in vivo. The effect of MMP inhibition was determined using the MMP inhibitor BB-94 and a moderately differentiated pancreatic cancer cell line (HPAC). In vitro, a dose response curve was generated over 5 days utilizing the MTT [3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. In vivo, using an established orthotopic model for pancreatic cancer (LD100 = 80 days), 22 nude mice with orthotopic tumors (30 were implanted) received either BB-94 or vehicle beginning 4 days prior to implantation and continuing to death or sacrifice on Day 70. Mice were weighted weekly. At death/sacrifice, tumors were weighted, volume determined, and metastases/ distant spread documented. In vitro, BB-94 had little effect on HPAC proliferation at 40 ng/ml but achieved progressively greater to near complete inhibition at doses up to 4000 ng/ml while maintaining cell viability. In vivo, BB-94 significantly increased length of survival (69 +/- 0.1 days vs. 56 +/- 3.1 days) and necropsy weight (25.7 +/- 1.67 g vs. 19.8 +/- 1.14 g) while decreasing metastatic rate (1 vs. 20) and tumor size (0.14 +/- 0.02 g vs. 0.65 +/- 0.1 g). MMP inhibition limits HPAC proliferation in a dose-dependent fashion without direct cytotoxic effects in vitro. Mice harboring orthotopic tumors treated with BB-94 demonstrated significant reductions in tumor weight, volume, and metastases which corresponded to increased animal weight and prolonged survival.

Animals↗
PubMed1997

Does the direction of portal blood flow determine outcome with small-diameter prosthetic H-graft portacaval shunt?

BACKGROUND: Partial portal decompression, as attained by small-diameter prosthetic H-graft portacaval shunting, continues to gain popularity because of favorable outcomes. This study was undertaken to determine whether the direction of preshunt or postshunt portal blood flow or reversal in the direction of portal flow occurred with shunting effect outcome after small-diameter prosthetic H-graft portacaval shunt. METHODS: In 56 consecutive patients the direction of portal flow was determined before and after shunting. The direction of portal blood flow before and after shunting and changes in the direction of portal flow that occur with shunting were correlated with 30-day and 1-year survival, as well as with the rate of postshunt encephalopathy. RESULTS: Portal pressures significantly decreased in all with shunting. Whether or not stratified by Child's classification, neither the preshunt nor postshunt direction of portal flow affected 30-day or 1-year survival or incidence of encephalopathy. Eleven patients (significant at p < 0.001, fisher's exact test) had reversal of portal blood flow with shunting without an increase in 30-day or 1-year survival or incidence of encephalopathy. CONCLUSIONS: Small-diameter prosthetic H-graft portacaval shunts significantly reduce portal pressure and lead to reversal of portal flow in significant numbers. Significant hepatic dysfunction is uncommon after shunting. Neither the direction of preshunt or postshunt portal blood flow nor the reversal of portal blood flow with shunting has an effect on clinical outcome after small-diameter prosthetic H-graft portacaval shunt.

Adult↗
PubMed1997

Tissue-specific cytokine production during experimental acute pancreatitis. A probable mechanism for distant organ dysfunction.

Our purpose was to determine if cytokines are produced systemically during acute pancreatitis. Proinflammatory cytokines are elevated during acute pancreatitis and have been implicated in the progression of pancreatitis-associated multiple organ dysfunction. Whether these mediators are produced within all tissues or very few specific organs is not known. Edematous pancreatitis was induced in adult male mice by IP injection of cerulein. Necrotizing pancreatitis was induced in young female mice by feeding a choline-deficient, ethionine supplemented diet. Animals were sacrificed as pancreatitis worsened, with multiple organs prepared for tissue mRNA and protein analysis by RT-PCR and immunoblotting. Pancreatitis severity was established by histologic grading and serum amylase and lipase. There was no cytokine mRNA or protein detectable prior to the induction of pancreatitis. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1-beta (IL-1 beta) mRNA and protein were detected within the pancreas early in the course of pancreatitis in both models, coinciding with the development of hyperamylasemia (both P < 0.001). Interleukin-6 was produced in the pancreas after pancreatitis was more fully developed (P < 0.001). IL-1 beta and TNF-alpha were subsequently produced in large amounts in lung, liver, and spleen but never within kidney, cardiac muscle, or skeletal muscle. A significant delay between pancreatic and distant organ cytokine production was always observed. It is concluded that proinflammatory cytokines are produced within the pancreas and within organs known to develop dysfunction during severe pancreatitis. Cytokine production is tissue specific, correlates with disease severity, and occurs within the pancreas first and subsequently within distant organs.

Actins↗
PubMed1997

Endothelial structural integrity is maintained during endotoxic shock in an interleukin-1 type 1 receptor knockout mouse.

The derangement of arterial endothelial cell morphology is a good indicator of a severe shock state. Because interleukin (IL)-1 has been implicated in this process, we examined the structural integrity of aortic endothelial cells in conjunction with serum IL-6 concentrations and nitric oxide levels, which are known to increase during endotoxemia in animals genetically devoid of the type 1 IL-1 receptor. Endotoxin (10 mg/kg Escherichia coli, injected intraperitoneally) (LD100) or saline vehicle was administered to adult male C57BL/129J wild-type control mice and C57BL/129J knockout mice possessing a homozygous deletion of the type 1 IL-1 receptor. The integrity of the aortic endothelium was determined by comparisons of ultrastructure. Mice injected with sterile vehicle showed normal endothelial ultrastructure with intact membranes. Wild-type and knockout control animals receiving saline vehicle showed a complete aortic endothelium (29.11 +/- .27 and 30.85 +/- .21 intact endothelial cells per millimeter of internal elastic lamina (IEL), respectively, p = N.S.). Endotoxin-treated wild-type animals showed extensive endothelial damage with most sections showing only denuded IEL on the luminal surface (1.83 +/- .38 cells/mm IEL, p < .001 vs. control). Knockout animals treated with endotoxin showed complete maintenance of endothelial structural integrity (34.08 +/- .57 cells/mm IEL, p < .001 vs. endotoxin-treated wild type) with ultrastructural morphology appearing identical to those given saline vehicle. Also, no apparent correlation was observed between serum IL-6 concentrations or serum nitric oxide levels and aortic endothelial damage. The maintenance of endothelial integrity in animals devoid of the IL-1 receptor confirms earlier observations of endothelial cell protection with IL-1 receptor antagonism and suggests that IL-1 contributes significantly to sepsis-induced endothelial damage.

Animals↗
PubMed1997

The effects of epidural anesthesia on the neuroendocrine response to major surgical stress: a randomized prospective trial.

It has long been held that the acute-phase and neuroendocrine response to stress requires afferent neural input for its propagation. To further clarify the role of afferent neural impulses in this process and to determine the ability of epidural anesthesia to attenuate the normal perioperative stress response, 39 patients undergoing uncomplicated abdominal aortic replacement were randomized to receive either general anesthesia with postoperative patient-controlled intravenous morphine (n = 19) or combined regional/general anesthesia with intraoperative epidural catheter anesthesia using Bupivacaine to the T4 dermatome level followed by postoperative epidural morphine (n = 20). The stress response was quantitated by blinded measurement of baseline and postoperative (0, 12, 24, 48, and 72 hours) serum cortisol, epinephrine norepinephrine, total catecholamines, interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)-alpha, and C-reactive protein (CRP). Total operative time (4.2 +/- 0.3 vs 4.3 +/- 0.4 hours), 72-hour fluid requirement (7.0 +/- 0.6 vs 6.8 +/- 0.71 mL), and length of hospitalization (7.8 +/- 1.4 vs 8.1 +/- 1.2 days) were not different between groups. All patients showed a significant increase in cortisol, epinephrine, norepinephrine, total catecholamines, CRP, and IL-6 in the postoperative period (P < 0.05). IL-1beta and TNF-alpha were less predictable and undetectable in most patients. There was no difference in any of the stress response indices between those patients receiving patient-controlled or epidural catheter anesthesia. In fact, the only parameter that was predictive of increased activation of the stress response was the length of operation, irrespective of anesthetic method. Those patients with operative times greater than 5 hours (n = 10) developed significantly higher CRP, IL-1beta, IL-6, and TNF-alpha levels (P < 0.05) at 12 and 24 hours postoperatively than those with total operative times less than 4 hours (n = 16). The neuroendocrine response to major surgical stress is propagated normally despite epidural blockade and is intensified with prolonged operative times. The inflammatory cytokines appear to play a major role in this process.

Anesthesia, Epidural↗
PubMed1996

Differential sensitivity to Escherichia coli infection in mice lacking tumor necrosis factor p55 or interleukin-1 p80 receptors.

OBJECTIVE: To determine the effect of targeted disruption of the cellular receptors of either tumor necrosis factor alpha (TNF-alpha) or interleukin-1 beta (IL-1 beta) during experimental gram-negative bacterial infection and endotoxemia. DESIGN: Transgenic (knockout [KO]) mice deficient in either the p55 TNF receptor (TNF RI) or the p80 IL-1 receptor (IL-1 RI) were challenged with intravenous lipopolysaccharide (endotoxin) or intraperitoneal live Escherichia coli 0111:B4. Mortality was assessed daily for 7 days. Serum endotoxin levels and quantitative blood cultures were monitored at multiple times during infection. SETTING: Surgical infectious disease research laboratory. MAIN OUTCOME MEASURES: Mortality, results of quantitative blood cultures, and serum endotoxin levels. RESULTS: Both TNF and IL-1 RI KO mice were resistant to endotoxin challenge (0% mortality for both groups) compared with control mice (100% mortality [P < .01]). In contrast, only the IL-1 RI KO mice were resistant to infection caused by viable gram-negative bacteria (43% mortality) compared with control mice (100% mortality [P < .01]). Infection led to 100% mortality in TNF RI KO mice. The IL-1 RI KO mice exhibited less bacteremia and diminished endotoxemia compared with control and TNF RI KO mice 18 and 24 hours after infection. CONCLUSION: The absence of either the TNF or the IL-1 RI receptor prevents cellular activation by each respective cytokine. Absence confers protection against intravenous endotoxin, which stimulates massive rapid release of cytokines into the systemic circulation. However, bacterial infection within the peritoneal cavity is known to cause more delayed cytokine release, and cytokines may act at the site of infection to enhance host defenses. We believe that IL-1 signaling may be more critical in provoking lethal systemic toxic effects than TNF signaling. However, TNF signaling may be an important component of host defense enhancement at the local site of infection.

Animals↗
PubMed1996

Transgenic animals demonstrate a role for the IL-1 receptor in regulating IL-1beta gene expression at steady-state and during the systemic stress induced by acute pancreatitis.

Interleukin-1 (IL-1) gene expression is selectively induced in tissues involved in multisystem organ failure during acute pancreatitis, suggesting a role in the pathogenesis of distant organ dysfunction. This study was undertaken to investigate the mechanism of pancreatitis-induced end organ cytokine production and to better understand the processes by which IL-1 production is regulated. Seventy adult male transgenic mice in which the type 1 IL-1 receptor had been deleted by gene targeting in embryonic stem cells were utilized (homozygous -/- IL-1R knockout). Acute pancreatitis was induced by one of two methods: (A) IP injections of caerulein (50 microgram/kg/hr x 4) with animals sacrificed at 0, .5, 1, 2, 4, 6, and 8 hr; (B) 48-hr exposure to a choline deficient ethionine supplemented (CDE) diet with animals sacrificed at 0 and 72 hr. Knockout animals were compared to strain-specific control mice expressing the normal wild-type IL-1 receptor gene in which pancreatitis was similarly induced. The severity of pancreatitis was stratified by serum amylase, lipase, and blind histologic grading. IL-1 mRNA production was determined within the pancreas, lungs, liver, and spleen by quantitative differential RT-PCR. Deletion of the IL-1R1 attenuated the severity of pancreatitis, reaching statistical significance in the less severe edematous model. There was little or no constitutive expression of IL-1 mRNA within any of the tissues examined from wild-type animals; however, knockout animals showed elevated steady-state levels in each tissue. IL-1 mRNA became detectable in all tissues of wild-type animals shortly after either form of pancreatitis became apparent and increased significantly with worsening pancreatitis. Despite the attenuated pancreatitis, knockout animals produced significantly greater levels of IL-1 mRNA in each tissue, typically demonstrating a 30-50% increase over time matched IL-1 mRNA production in wild-type animals which was not pancreatitis model dependent. We conclude that genetic deletion of IL-1 receptors results in the overproduction of IL-1 mRNA in organs known to produce cytokines during pancreatitis even when the severity of pancreatitis is lessened. This suggests that a negative feedback loop exists between the IL-1 receptor and IL-1 gene expression.

Acute Disease↗
PubMed1996

Intrapancreatic interleukin-1beta gene expression by specific leukocyte populations during acute pancreatitis.

The importance of interleukin-1beta (IL-1beta) in the pathogenesis of acute pancreatitis has been demonstrated by dramatic attenuation of pancreatic destruction and significant increases in survival when its actions are inhibited. The pancreas has been shown to be a major producer of IL-1beta during pancreatitis but the cell(s) of origin remains unknown. Hypothesizing that infiltrating leukocytes contribute substantially, the intrapancreatic production of IL-1beta was examined after specific leukocyte populations were manipulated in vivo prior to the induction of pancreatitis. Sixty-four adult male Swiss mice were assigned to one of four groups 48 hr prior to induction of pancreatitis: (1) PMN depletion via anti-murine PMN antiserum. [PMN-d], (2) macrophage (Mphi) depletion via anti-macrophage antiserum [Mphi-d], (3) PMN and Mphi depletion [PMN+Mphi-d], and (4) Immunocompetent Pancreatitis. Edematous pancreatitis was induced in all experimental groups by caerulein (50 microg/kg/hr ip X 4). Animals were sacrificed 6 hr after induction of pancreatitis with severity determined by blind histologic grading and serum amylase, lipase, and interleukin-6 (IL-6) levels. Intrapancreatic IL-1beta production was determined by immunohistochemistry and semiquantitative differential RT-PCR. Pancreatitis developed in all animals receiving caerulein; however, leukocyte-depleted animals showed significantly attenuated levels of serum amylase, lipase, and IL-6, as well as lower histologic severity scores. Similarly, pancreatitis induction in immunocompetent mice showed pancreatic infiltration of IL-1beta-producing cells, whereas the leukocyte-depleted animals had significantly decreased numbers (PMN+Mphi-d < Mphi-d < PMN-d). IL-1beta mRNA was upregulated in all animals developing pancreatitis with significantly lower levels seen in the leukocyte-depleted groups. We conclude that infiltrating leukocytes, both neutrophils and macrophages, are responsible for the majority of intrapancreatic IL-1beta production during acute pancreatitis. The elimination of leukocytes and their products, including IL-1beta, significantly decreases the severity of pancreatic destruction.

Acute Disease↗
PubMed1996

Differentiation of pancreatic ductal carcinoma cells associated with selective expression of protein kinase C isoforms.

BACKGROUND: The signal transduction pathways important in regulating the growth and differentiation of malignant cells are poorly understood. Recent evidence has implicated activation of the protein kinase C (PKC) family of signaling proteins in pancreatic carcinoma during cytokine-induced cytostasis and differentiation. METHODS: A human pancreatic adenocarcinoma (HPAC) cell line was exposed to tumor necrosis factor-alpha (TNF-alpha; 40 ng/ml) for 6 days. Cytostasis and viability were confirmed by daily MTT [(3(4,5)-dimethyl-thiazol-2-yl) 2,5-diphenyl-tetrazolium bromide] and trypan exclusion assay. Protein fractions were isolated daily and subjected to immunoblot analysis for the normal (terminally differentiated) pancreatic ductal cell marker carbonic anhydrase II (CA II) as well as specific PKC isoforms (alpha, beta, gamma, eta, and zeta). RESULTS: Growth arrest occurred in HPAC cells after exposure to TNF-alpha for 48 h, with viability maintained above 90% throughout the 6-day time course. CA II immunoreactivity was not detected in untreated controls but appeared after 2 days of TNF-alpha exposure, peaking on day 6. Concurrently, TNF-alpha induced the selective downregulation of PKC-alpha, whereas PKC-gamma levels increased. PKC-beta and PKC-eta immunoreactivity did not change. The atypical PKC-zeta isoform developed a doublet banding pattern in response to TNF-alpha, although overall PKC-zeta levels did not change. CONCLUSIONS: TNF-alpha-induced growth arrest and differentiation in HPAC cells is associated with the selective downregulation of PKC-alpha and upregulation of PKC-gamma.

Carbonic Anhydrases↗
PubMed1996

Timing of tumor necrosis factor antagonism is critical in determining outcome in murine lethal acute pancreatitis.

BACKGROUND: Tumor necrosis factor (TNF) is produced in large amounts within the pancreas, lungs, and liver during severe acute pancreatitis and is believed to mediate many of the detrimental consequences typical of this disease. Investigations into the benefit of TNF antagonism have suggested that TNF may also mediate processes that are protective to the host. METHODS: With the hypothesis that timing plays a role in these dissenting views, TNF was antagonized either prophylactically or therapeutically with a recombinant form of the soluble type I TNF receptor (TNFbp) during a lethal model of necrotizing pancreatitis induced by feeding a choline-deficient diet. Mortality was determined for 10 days in 390 female mice divided into three groups: control, TNFbp early (time, 0 to 5 days), and TNFbp late (time, 1.5 to 5 days). Pancreatitis severity and cytokine production were assessed daily. RESULTS: Animals in the control group had a 75% mortality rate that was significantly decreased by prophylactic TNF blockade (64%, p < 0.05). Delaying TNF antagonism until serum cytokines were elevated and pancreatitis was manifest decreased mortality to 42% (p < 0.001 versus control, p < 0.01 versus early). Early and late TNF blockade decreased pancreatic edema and serum amylase, lipase, interleukin-1, and interleukin-6 (all p < 0.05) but not TNF. Late antagonism typically resulted in the greatest attenuation of all these parameters. CONCLUSIONS: Blockade of TNF by the administration of a soluble TNF receptor attenuates the severity of pancreatitis, decreases the production of associated inflammatory cytokines, and significantly improves survival. Delaying antagonism until pancreatitis is manifest and circulating cytokines are elevated but not yet maximal appears to be more protective than simple prophylactic TNF antagonism.

Acute Disease↗
PubMed1996

Active interleukin-1 receptor required for maximal progression of acute pancreatitis.

OBJECTIVE: The authors' aim was to determine the requirement for an active interleukin (IL)-1 receptor during the development and progression of acute pancreatitis. SUMMARY OF BACKGROUND DATA: Interleukin-1 is a pro- inflammatory cytokine that has been shown to be produced during acute pancreatitis. Earlier animal studies of moderate and severe pancreatitis have shown that blockade of this powerful mediator is associated with attenuated pancreatic destruction and dramatic increases in survival. The exact role played by IL-1 and the requirement for activation of its receptor in the initiation and progression of pancreatitis is unknown. METHODS: Conventional and IL-1 receptor "knockout" animals were used in parallel experiments of acute pancreatitis induced by intraperitoneal injection of cerulean (50 microg/kg every 1 hour X 4). The conventional mouse strain had the IL-1 receptor blocked prophylactically by means of a recombinant IL-1 receptor antagonist (10 mg/kg injected intraperitoneally every 2 hours). The second mouse strain was genetically engineered by means of gene targeting in murine embryonic stem cells to be devoid of type 1 IL-1 receptor (IL-1 receptor knockout). Animals were killed at 0, 0.5, 1, 2, 4, and 8 hours, with the severity of pancreatitis determined by serum amylase, lipase, and IL-6 levels and blind histologic grading. Strain-specific controls were used for comparison. RESULTS: The genetic absence of the IL-1 receptor or its pharmacologic blockade resulted in significantly attenuated pancreatic vacuolization, edema, necrosis, inflammation, and enzyme release. Serum IL-6, a marker of inflammation severity, was dramatically decreased in both groups. CONCLUSIONS: Activation of the IL-1 receptor is not required for the development of pancreatitis but apparently is necessary for the maximal propagation of pancreatic injury and its associated inflammation.

Acute Disease↗
PubMed1996

Fluconazole increases bactericidal activity of neutrophils through non--cytokine-mediated pathway.

BACKGROUND: Polymorphonuclear neutrophils (PMNs) preincubated with fluconazole (FCZ) demonstrate enhanced bactericidal activity in vitro. OBJECTIVE: This study was undertaken to determine the role of cytokines in FCZ-induced augmentation of PMN function. METHODS: PMNs were preincubated with PBS or FCZ and exposed to Escherichia coli. Cell culture supernatants and mRNA were isolated after preincubation and again after exposure to E. coli. Tumor necrosis factor-alpha, interleukin (IL)-1 beta, and IL-8 protein and mRNA levels were determined using enzyme-linked immunosorbent assay and polymerase chain reaction, respectively. Results were compared using the Student's t test. RESULTS: Preincubation of PMNs with FCZ resulted in enhanced killing but no difference in cytokine protein or mRNA levels when compared to control. After exposure to E. coli, PMNs significantly up-regulate IL-8 and tumor necrosis factor-alpha independent of the solution with which they were preincubated. CONCLUSIONS: Up-regulation of the cytokine cascade plays a minor role, at most, in the mechanism through which FCZ augments the bactericidal activity of PMNs.

Antifungal Agents↗
PubMed1995

Acute pancreatitis induces intrapancreatic tumor necrosis factor gene expression.

OBJECTIVE: To examine the intrapancreatic production of tumor necrosis factor (TNF) alpha and define its cell of origin during acute pancreatitis. DESIGN: Acute necrotizing pancreatitis was induced in adult male mice by administering cerulein (50 micrograms/kg intraperitoneally four times over 3 hours). Animals were killed at 0, 0.5, 1, 2, 4, 6, and 8 hours, with the severity of pancreatitis established by blind histologic grading and serum amylase, lipase, and TNF levels. The expression of TNF messenger RNA within the pancreas was established by the reverse transcription polymerase chain reaction. Intrapancreatic TNF protein was analyzed by enzyme-linked immunosorbent assay, Western blot, and immunohistochemical methods. RESULTS: Acute pancreatitis was manifest within 1 hour of the first cerulein injection and increased in severity through 8 hours. There was no constitutive expression of TNF messenger RNA within the pancreas, but transcripts were induced within 30 minutes following the onset of pancreatitis, increasing through 4 hours. Intrapancreatic and serum TNF peptide levels became detectable at 1 hour and increased over 6 hours (both P < .001 vs control), with intrapancreatic levels rising faster and attaining concentrations three times higher than time-matched serum levels (P < .01). Immunohistochemical staining demonstrated the progressive infiltration of macrophages into the pancreas that stained heavily for TNF (P < .01 vs control). CONCLUSIONS: Tumor necrosis factor gene expression is induced locally during acute pancreatitis, resulting in large amounts of intrapancreatic TNF with levels consistently higher than those found in the serum. The overall rise in both tissue and serum TNF concentrations correlates directly with the severity of pancreatic damage and inflammation. The infiltrating macrophage appears to contribute most to this process.

Acute Disease↗
PubMed1995

Decreased mortality of severe acute pancreatitis after proximal cytokine blockade.

OBJECTIVE: This study determined the ability of interleukin-1 receptor antagonist (IL-1ra) to decrease the mortality of experimental acute pancreatitis. The response of the inflammatory cytokine cascade and its subsequent effects on pancreatic morphology were measured to determine the role of these peptides in mediating pancreatic injury. SUMMARY BACKGROUND DATA: Previous studies have shown that proinflammatory cytokines are produced in large amounts during acute pancreatitis and that blockade at the level of the IL-1 receptor significantly decreases intrinsic pancreatic damage. The subsequent effect on survival is not known. METHODS: A lethal form of acute hemorrhagic necrotizing pancreatitis was induced in young female mice by feeding a choline-deficient, ethionine supplemented (CDE) diet for 72 hours. For determination of mortality, the animals were divided into 3 groups of 45 animals each: control subjects received 100/microL normal saline intraperitoneally every 6 hours for 5 days; IL-1ra early mice received recombinant interleukin-1 receptor antagonist 15 mg/kg intraperitoneally every 6 hours for 5 days beginning at time 0; IL-1ra late mice received IL-1ra 15 mg/kg intraperitoneally every 6 hours for 3.5 days beginning 1.5 days after introduction of the CDE diet. A parallel experiment was conducted simultaneously with a minimum of 29 animals per group, which were sacrificed daily for comparisons of serum amylase, lipase, IL-1, IL-6, tumor necrosis factor-alpha, IL-1ra, pancreatic wet weight, and blind histopathologic grading. RESULTS: The 10-day mortality in the untreated control group was 73%. Early and late IL-1ra administration resulted in decreases of mortality to 44% and 51%, respectively (both p < 0.001). Interleukin-1 antagonism also was associated with a significant attenuation in the rise in pancreatic wet weight and serum amylase and lipase in both early and late IL-1ra groups (all p < 0.05). All control animals developed a rapid elevation of the inflammatory cytokines, with maximal levels reached on day 3. The IL-1ra-treated animals, however, demonstrated a blunted rise of these mediators (all p < 0.05). Blind histologic grading revealed an overall decrease in the severity of pancreatitis in those animals receiving the antagonist. CONCLUSIONS: Early or late blockade of the cytokine cascade at the level of the IL-1 receptor significantly decreases the mortality of severe acute pancreatitis. The mechanism by which this is accomplished appears to include attenuation of systemic inflammatory cytokines and decreased pancreatic destruction.

Acute Disease↗
PubMed1995

Maintenance of dynamic microvascular function and structure in a rat model of endotoxic shock by blockade of the interleukin-1 receptor.

The microvascular and macrovascular effects of IL-1 receptor antagonist (IL-1ra) were examined in rat cremaster muscle A1, A2, and A3 arterioles by videomicroscopy to better define its protective effects during endotoxemia. Mean arterial pressure (MAP), arteriolar diameters, and responses to norepinephrine (NE) and acetylcholine (ACh) were examined hourly after the administration of Escherichia coli endotoxin (6 mg/kg intravenously). Animals received saline (Control) or IL-1ra (.2 mg/kg/min intravenously) beginning 1 h prior to endotoxin. Serum tumor necrosis factor-alpha (TNF-alpha) and nitrate/nitrite (NO) were determined terminally. Aortic endothelium was examined by electron microscopy (EM). All Control animals, but no IL-1ra animals, died within 6 h (p < .01).IL-1ra significantly attenuated endotoxin-induced vasoconstriction of A1 and A2 arterioles (p < .01), while MAP and NE threshold remained at baseline (p < .01 vs. Control). Serum TNF and NO were elevated following endotoxin (p < .001), but only TNF was decreased (p < .005) in animals receiving IL-1ra. Aortic endothelium was damaged in all Control animals but was spared with IL-1 antagonism. IL-1ra increases survival during endotoxic shock and attenuates production of TNF but not NO. IL-1ra maintains MAP, arteriolar diameters, reactivity of arterioles to NE and ACh, and the integrity of the aortic endothelium.

Acetylcholine↗