Biomedical subjects

R L Warner

Publications and source records attributed to R L Warner.

At least 19 recordsLinked to original sources

PubMed2001

Role of IL-18 in acute lung inflammation.

We have examined the role of IL-18 after acute lung inflammation in rats caused by intrapulmonary deposition of IgG immune complexes. Constitutive IL-18 mRNA and protein expression (precursor form, 26 kDa) were found in normal rat lung, whereas in inflamed lungs, IL-18 mRNA was up-regulated; in bronchoalveolar (BAL) fluids, the 26-kDa protein form of IL-18 was increased at 2-4 h in inflamed lungs and remained elevated at 24 h, and the "mature" protein form of IL-18 (18 kDa) appeared in BAL fluids 1-8 h after onset of inflammation. ELISA studies confirmed induction of IL-18 in inflamed lungs (in lung homogenates and in BAL fluids). Prominent immunostaining for IL-18 was found in alveolar macrophages from inflamed lungs. When rat lung macrophages, fibroblasts, type II cells, and endothelial cells were cultured in vitro with LPS, only the first two produced IL-18. Intratracheal administration of rat recombinant IL-18 in the lung model caused significant increases in lung vascular permeability and in BAL content of neutrophils and in BAL content of TNF-alpha, IL-1beta, and cytokine-induced neutrophil chemoattractant, whereas intratracheal instillation of anti-IL-18 greatly reduced these changes and prevented increases in BAL content of IFN-gamma. Intratracheal administration of the natural antagonist of IL-18, IL-18 binding protein, resulted in suppressed lung vascular permeability and decreased BAL content of neutrophils, cytokines, and chemokines. These findings suggest that endogenous IL-18 functions as a proinflammatory cytokine in this model of acute lung inflammation, serving as an autocrine activator to bring about expression of other inflammatory mediators.

Acute Disease↗

PubMed2001

Regulatory effects of eotaxin on acute lung inflammatory injury.

Eotaxin, which is a major mediator for eosinophil recruitment into lung, has regulatory effects on neutrophil-dependent acute inflammatory injury triggered by intrapulmonary deposition of IgG immune complexes in rats. In this model, eotaxin mRNA and protein were up-regulated during the inflammatory response, resulting in eotaxin protein expression in alveolar macrophages and in alveolar epithelial cells. Ab-induced blockade of eotaxin in vivo caused enhanced NF-kappaB activation in lung, substantial increases in bronchoalveolar lavage levels of macrophage inflammatory protein (MIP)-2 and cytokine-induced neutrophil chemoattractant (CINC), and increased MIP-2 and CINC mRNA expression in alveolar macrophages. In contrast, TNF-alpha levels were unaffected, and IL-10 levels fell. Under these experimental conditions, lung neutrophil accumulation was significantly increased, and vascular injury, as reflected by extravascular leak of (125)I-albumin, was enhanced. Conversely, when recombinant eotaxin was administered in the same inflammatory model of lung injury, bronchoalveolar lavage levels of MIP-2 were reduced, as was neutrophil accumulation and the intensity of lung injury. In vitro stimulation of rat alveolar macrophages with IgG immune complexes greatly increased expression of mRNA and protein for MIP-2, CINC, MIP-1alpha, MIP-1beta, TNF-alpha, and IL-1beta. In the copresence of eotaxin, the increased levels of MIP-2 and CINC mRNAs were markedly diminished, whereas MIP-1alpha, MIP-1beta, TNF-alpha, and IL-1beta expression of mRNA and protein was not affected. These data suggest that endogenous eotaxin, which is expressed during the acute lung inflammatory response, plays a regulatory role in neutrophil recruitment into lung and the ensuing inflammatory damage.

Acute Disease↗

PubMed2001

The role of metalloelastase in immune complex-induced acute lung injury.

Matrix metalloproteases (MMPs) are a group of zinc-dependent endopeptidases that can degrade every component of the extracellular matrix. Under normal circumstances, the levels of MMPs are tightly regulated at both transcriptional and posttranscriptional levels. However, they are up-regulated in pathological states such as inflammation. Previous investigations have suggested that MMP-12 (metalloelastase) may be an important mediator in the pathogenesis of chronic lung injury. In this study we investigated the role of metalloelastase in the pathogenesis of acute lung injury using mice containing a targeted disruption of the metalloelastase gene. Neutrophil influx into the alveolar space in metalloelastase-deficient animals was reduced to approximately 50% of that observed in parent strain mice following the induction of injury by immune complexes. In addition, lung permeability in metalloelastase-deficient mice was approximately 50% of that of injured parent strain animals with normal levels of metalloelastase and this was correlated with histological evidence of less lung injury in the metalloelastase-deficient animals. Collectively, the data suggest that metalloelastase is necessary for the full development of acute alveolitis in this model of lung injury. Further, the data suggest that reduced injury in metalloelastase-deficient mice is due in part to decreased neutrophil influx into the alveolar space.

Acute Disease↗

PubMed2001

Role of stromelysin 1 and gelatinase B in experimental acute lung injury.

Matrix metalloproteinases (MMPs) are upregulated locally in sites of inflammation, including the lung. Several MMP activities are upregulated in acute lung injury models but the exact role that these MMPs play in the development of the lung injury is unclear due to the absence of specific inhibitors. To determine the involvement of individual MMPs in the development of lung injury, mice genetically deficient in gelatinase B (MMP-9) and stromelysin 1 (MMP-3) were acutely injured with immunoglobulin G immune complexes and the intensity of the lung injury was compared with genetically identical wild-type (WT) mice with normal MMP activities. In the WT mice there was upregulation of gelatinase B and stromelysin 1 in the injured lungs which, as expected, was absent in the genetically deficient gelatinase B- and stromelysin 1-deficient mice, respectively. In the deficient mice there was little in the way of compensatory upregulation of other MMPs. The gelatinase B- and the stromelysin 1-deficient mice had less severe lung injury than did the WT controls, suggesting that both MMPs are involved in the pathogenesis of the lung injury. Further, the mechanism of their involvement in the lung injury appears to be different, with the stromelysin 1-deficient mice having a reduction in the numbers of neutrophils recruited into the lung whereas the gelatinase B-deficient mice had the same numbers of lung neutrophils as did the injured WT controls. These studies indicate, first, that both gelatinase B and stromelysin 1 are involved in the development of experimental acute lung injury, and second, that the mechanisms by which these individual MMPs function appear to differ.

Animals↗

PubMed2000

Time-dependent inhibition of immune complex-induced lung injury by catalase: relationship to alterations in macrophage and neutrophil matrix metalloproteinase elaboration.

Rats were subjected to acute lung injury by the intra-alveolar formation of IgG immune complexes of bovine serum albumin (BSA) and anti-BSA. In this model of injury, complement activation occurs and large numbers of neutrophils invade the interstitium and alveolar space. In the present study, animals were treated with intratracheal catalase concomitantly with anti-BSA or after a lag period of 5-120 min. Catalase treatment at time-zero or at 5 min post injury failed to prevent lung injury as indicated by permeability change, histological features, and neutrophil influx. However, treatment after a delay of 15-30 min (but not 120 min) afforded substantial protection. Consistent with past findings [19], lung injury was accompanied by an accumulation of matrix metalloproteinase 9 (MMP-9) in bronchoalveolar lavage (BAL) fluid. There was a strong correlation between inhibition of injury and reduction in MMP-9 levels. In vitro studies conducted in parallel revealed that unstimulated alveolar macrophages did not produce measurable MMP-9, while there was a large induction following exposure to the same immune complexes that initiated injury in vivo. MMP-2 was also slightly upregulated under the same conditions. Concomitant treatment with catalase greatly inhibited MMP-9 production by macrophages in response to immune complexes, but this treatment had little effect on basal production of either MMP-9 or MMP-2 by macrophage. The same concentration of catalase that suppressed MMP-9 elaboration also inhibited the production of tumor necrosis factor alpha. In contrast, when neutrophils were treated with catalase and then exposed to immune complexes, the antioxidant failed to prevent the release of either MMP-2 or MMP-9. Taken together, these findings demonstrate that antioxidant treatment interferes with elaboration of MMPs by alveolar macrophages. Protection against lung injury is correlated with reduction in MMP levels in the BAL fluid.

Animals↗

PubMed2000

Role of CC chemokines (macrophage inflammatory protein-1 beta, monocyte chemoattractant protein-1, RANTES) in acute lung injury in rats.

The role of the CC chemokines, macrophage inflammatory protein-1 beta (MIP-1 beta), monocyte chemotactic peptide-1 (MCP-1), and RANTES, in acute lung inflammatory injury induced by intrapulmonary deposition of IgG immune complexes injury in rats was determined. Rat MIP-1 beta, MCP-1, and RANTES were cloned, the proteins were expressed, and neutralizing Abs were developed. mRNA and protein expression for MIP-1 beta and MCP-1 were up-regulated during the inflammatory response, while mRNA and protein expression for RANTES were constitutive and unchanged during the inflammatory response. Treatment of rats with anti-MIP-1 beta Ab significantly decreased vascular permeability by 37% (p = 0.012), reduced neutrophil recruitment into lung by 65% (p = 0.047), and suppressed levels of TNF-alpha in bronchoalveolar lavage fluids by 61% (p = 0.008). Treatment of rats with anti-rat MCP-1 or anti-rat RANTES had no effect on the development of lung injury. In animals pretreated intratracheally with blocking Abs to MCP-1, RANTES, or MIP-1 beta, significant reductions in the bronchoalveolar lavage content of these chemokines occurred, suggesting that these Abs had reached their targets. Conversely, exogenously MIP-1 beta, but not RANTES or MCP-1, caused enhancement of the lung vascular leak. These data indicate that MIP-1 beta, but not MCP-1 or RANTES, plays an important role in intrapulmonary recruitment of neutrophils and development of lung injury in the model employed. The findings suggest that in chemokine-dependent inflammatory responses in lung CC chemokines do not necessarily demonstrate redundant function.

Acute Disease↗

PubMed2000

Regulatory role of Th-2 cytokines, IL-10 and IL-4, in cardiac allograft rejection.

The host response to alloantigen results in T- and B-cell activation, upregulation of Class II MHC antigens, and cytokine production by Th-1 cells, resulting in generation of IL-2 and IFN gamma. Th-2 cell responses produce IL-4 and IL-10 which may shift the immune response from the Th-1 pathway to Th-2 responses, favoring Ig production. This could imply that Th-2-related cytokines protect allografts. In the following studies, employing cardiac heterotopic allografts in rats (Brown Norway into Lewis), we investigated regulatory roles of Th-2-related cytokines IL-4 and IL-10. Two strategies were used in animals receiving allografts: antibody-induced blocking of endogenous IL-4 or IL-10 and exogenous administration of either interleukin. Antibody to IL-4 failed to alter the rejection time, whereas anti-IL-10 greatly accelerated the rejection process. Northern blot analysis of RNA from allografted hearts revealed mRNA for both IL-4 and IL-10, while immunostaining showed strong staining for IL-10 and very weak staining for IL-4. Exogenous administration of either IL-4 or 10 caused prolongation of allograft rejection times. These findings suggest that in rat cardiac allografts intrinsic IL-10 functions to attenuate the rejection process.

Animals↗

PubMed2000

Role of RANTES in experimental cardiac allograft rejection.

The host response to alloantigen results in upregulation of Class II MHC antigens and associated cytokine production (especially IL-2 and interferon-gamma (IFN-gamma)) as well as lymphocytic infiltration and cellular activation which leads to graft damage/destruction. RANTES (Regulated upon Activation, Normal T-cell Expressed and presumably Secreted) is a member of the beta subfamily (CC) of chemokines and has been shown to function as a lymphocyte chemoattractant. We now describe the requirement for RANTES in cardiac heterotopic allograft (brown Norway into Lewis rats) rejection in rats. By Northern blot analysis, mRNA could be detected in allografts at 6 and 8 days post-transplantation but not in isogenic (Lewis) grafts. RANTES protein could be demonstrated by Western blot analysis in homogenates from allografts at day 8 but not at day 0 and could not be identified in isogenic cardiac transplants. By immunostaining, RANTES protein was present in mononuclear cells of allografts at day 6 but was absent in the isogenic transplants. When rats were treated with anti-RANTES serum, there was a significant delay in rejection time (cessation of beating) of the allografts. These data demonstrate that expression of RANTES in rat cardiac allografts is linked to the rejection phenomenon.

Amino Acid Sequence↗

PubMed2000

L-Selectin and chemokine response after liver ischemia and reperfusion.

BACKGROUND: L-selectin plays an important role in the early phase of PMNs recruitment in the hepatic microvasculature following liver ischemia and reperfusion (I/R). Leukocyte cytokine chemoattractants (chemokines) cause polymorphonuclear neutrophil (PMN) activation in I/R injury. In this study, we examined the role of L-selectin in the production of chemokines in the liver and lung inflammatory response following 90 min of warm ischemia. STUDY DESIGN: Thirty-six C57BL/6 mice were subjected to partial liver ischemia for a period of 90 min. Three groups of animals were included (n = 12 per group)-sham group, ischemic control, and the ischemic group receiving monoclonal antibody against L-selectin. We evaluated at 3 h: liver injury measurements, serum chemokines (MIP-2 and MIP-1alpha), liver and lung tissue myeloperoxidase (MPO), and liver and lung histology. Statistical analysis included ANOVA, Student-Newman-Keuls', and Kruskal-Wallis multiple comparison Z-value tests. RESULTS: The ischemic group treated with anti-L-selectin showed significant decreases in liver enzyme levels and a marked decrease in serum MIP-2 (P < 0.05) when compared to ischemic controls. No reduction in serum MIP-1alpha was noted; however, neutrophil infiltration was significantly ameliorated in the liver and in the lung, as reflected by decreased MPO levels (P < 0.05). Improved histopathological features were observed in the anti-L-selectin-treated group compared to ischemic controls in the liver and the lung. CONCLUSIONS: Our study suggests an important role for L-selectin in the pathogenesis of liver I/R and the production of chemokines. Anti-L-selectin treatment resulted in improved liver function, decreased neutrophil infiltration, and decreased MIP-2 chemokine response.

Animals↗

PubMed2000

A rodent model of cocaine abstinence syndrome.

This study introduces a rat model of cocaine abstinence syndrome based on quantitation of spontaneously emitted behaviors following termination of continuous drug exposure (analogous to established methods of assessing morphine and nicotine abstinence). Groups of eight male S-D rats were infused SC for 7 days via an osmotic minipump with saline alone or with 40 or 60 mg/kg/day cocaine HCl. Pumps were removed and rats were observed at 12, 24, 36, and 48 h postremoval. Each 15-min observation employed a checklist of abstinence signs including ptosis, chews, teeth chatters, gasps, writhes, seminal ejaculations, head shakes, and tremors. The high infusion rate group displayed significantly more signs than the low infusion rate group, which in turn, displayed significantly more signs than the saline group. Cocaine injection significantly reduced signs by 83.3%, while saline injection reduced them by only 4.9%. In another experiment, rats infused with 60 mg/kg/day showed significantly more signs 36 h postinfusion than before infusion, during infusion and 84 h postinfusion. Finally, 6.5 days of infusion resulted in significantly more abstinence signs than did 1.5 days of infusion. This rapid and simple model quantitated cocaine abstinence syndrome in a manner that was cocaine-reversible and related to the rate and duration of drug infusion.

Animals↗

PubMed2000

P-selectin and chemokine response after liver ischemia and reperfusion.

BACKGROUND: P-selectin plays a major role in the earliest phase of polymorphonuclear neutrophil recruitment in the hepatic microvasculature after liver ischemia and reperfusion. Leukocyte cytokine chemoattractants (chemokines) cause polymorphonuclear neutrophil activation in ischemia and reperfusion injury. In this study, we examined the role of P-selectin in the production of chemokines in the liver and lung inflammatory response after 90 minutes of warm ischemia. STUDY DESIGN: Thirty-six C57BL/6 mice were subjected to partial liver ischemia for 90 minutes. Three groups of animals were included (n = 12 per group): the sham group, the ischemic control group, and the P-selectin-deficient gene targeted mice group. After 3 hours, we evaluated liver injury measurements, serum chemokines (MIP[macrophage inflammatory protein]-1alpha and MIP-2), liver and lung tissue myeloperoxidase, and liver and lung histology. Statistical analysis included ANOVA, Student-Newman-Keuls', and Kruskal-Wallis Multiple Comparison Z-value tests. RESULTS: P-selectin-deficient mice showed significant decreases in liver enzyme levels (p < 0.05) and marked decreases in serum MIP-1alpha and MIP-2 chemokine determinations (p < 0.05) when compared with ischemic controls. Neutrophil infiltration was significantly ameliorated in the liver (p < 0.05) and markedly decreased in the lung, as reflected by decreased MPO levels. Improved histopathologic features in the liver and lung were observed in the P-selectin-deficient mice group compared with ischemic controls. CONCLUSIONS: Our study confirms the key role of P-selectin in the pathogenesis of liver ischemia and reperfusion and the production of chemokines. P-selectin-deficient animals had improved liver function, decreased neutrophil infiltration, and decreased MIP- 1alpha and MIP-2 responses.

Analysis of Variance↗

PubMed2000

Vitamin A antagonizes decreased cell growth and elevated collagen-degrading matrix metalloproteinases and stimulates collagen accumulation in naturally aged human skin.

Damage to human skin due to ultraviolet light from the sun (photoaging) and damage occurring as a consequence of the passage of time (chronologic or natural aging) are considered to be distinct entities. Photoaging is caused in part by damage to skin connective tissue by increased elaboration of collagen-degrading matrix metalloproteinases, and by reduced collagen synthesis. As matrix metalloproteinase levels are known to rise in fibroblasts as a function of age, and as oxidant stress is believed to underlie changes associated with both photoaging and natural aging, we determined whether natural skin aging, like photoaging, gives rise to increased matrix metalloproteinases and reduced collagen synthesis. In addition, we determined whether topical vitamin A (retinol) could stimulate new collagen deposition in sun-protected aged skin, as it does in photoaged skin. Sun-protected skin samples were obtained from 72 individuals in four age groups: 18-29 y, 30-59 y, 60-79 y, and 80+ y. Histologic and cellular markers of connective tissue abnormalities were significantly elevated in the 60-79 y and 80+ y groups, compared with the two younger age groups. Increased matrix metalloproteinase levels and decreased collagen synthesis/expression were associated with this connective tissue damage. In a separate group of 53 individuals (80+ y of age), topical application of 1% vitamin A for 7 d increased fibroblast growth and collagen synthesis, and concomitantly reduced the levels of matrix-degrading matrix metalloproteinases. Our findings indicate that naturally aged, sun-protected skin and photoaged skin share important molecular features including connective tissue damage, elevated matrix metalloproteinase levels, and reduced collagen production. In addition, vitamin A treatment reduces matrix metalloproteinase expression and stimulates collagen synthesis in naturally aged, sun-protected skin, as it does in photoaged skin.

Adolescent↗

PubMed1999

Endothelial targeting and enhanced antiinflammatory effects of complement inhibitors possessing sialyl Lewisx moieties.

The complement inhibitor soluble complement receptor type 1 (sCR1) and a truncated form of sCR1, sCR1[desLHR-A], have been generated with expression of the selectin-reactive oligosaccharide moiety, sialyl Lewisx (sLex), as N-linked oligosaccharide adducts. These modified proteins, sCR1sLex and sCR1[desLHR-A]sLex, were assessed in the L-selectin- and P-selectin-dependent rat model of lung injury following systemic activation of complement by cobra venom factor and in the L-selectin-, P-selectin-, and E-selectin-dependent model of lung injury following intrapulmonary deposition of IgG immune complexes. In the cobra venom factor model, sCR1sLex and sCR1[desLHR-A]sLex caused substantially greater reductions in neutrophil accumulation and in albumin extravasation in lung when compared with the non-sLex-decorated forms. In this model, increased lung vascular binding of sCR1sLex and sCR1[desLHR-A]sLex occurred in a P-selectin-dependent manner, in contrast to the absence of any increased binding of sCR1 or sCR1[desLHR-A]. In the IgG immune complex model, sCR1[desLHR-A]sLex possessed greater protective effects relative to sCR1[desLHR-A], based on albumin extravasation and neutrophil accumulation. Enhanced protective effects correlated with greater lung vascular binding of sCR1[desLHR-A]sLex as compared with the non-sLex-decorated form. In TNF-alpha-activated HUVEC, substantial in vitro binding occurred with sCR1[desLHR-A]sLex (but not with sCR1[desLHR-A]). This endothelial cell binding was blocked by anti-E-selectin but not by anti-P-selectin. These data suggest that sLex-decorated complement inhibitors have enhanced antiinflammatory effects and appear to have enhanced ability to localize to the activated vascular endothelium.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1999

Requirement for interleukin-12 in the pathogenesis of warm hepatic ischemia/reperfusion injury in mice.

Hepatic ischemia and reperfusion causes neutrophil-dependent liver injury. Although the mechanisms of ischemia/reperfusion-induced liver neutrophil recruitment are somewhat understood, less is known regarding the early events that initiate the inflammatory injury. Using a murine model of partial hepatic ischemia and reperfusion, we evaluated the role of endogenous interleukin (IL)-12 in this inflammatory response. Hepatic ischemia for 90 minutes and reperfusion for up to 4 hours resulted in hepatocyte expression of IL-12. By 8 hours of reperfusion there were large increases in serum levels of interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha). In addition, hepatic ischemia/reperfusion caused significant increases in liver neutrophil recruitment, hepatocellular injury, and liver edema, as defined by liver myeloperoxidase content, serum alanine aminotransferase, and liver wet to dry weight ratios, respectively. In mice treated with neutralizing antibody to IL-12 and in mice deficient in the IL-12 p40 gene, ischemia/reperfusion-induced increases in IFNgamma and TNFalpha were greatly diminished. These conditions also caused significant reductions in liver myeloperoxidase content and attenuated the parameters of liver injury. The data suggest that IL-12 is required for the full induction of injury after hepatic ischemia and reperfusion.

Alanine Transaminase↗

PubMed1999

Eotaxin expression in Sephadex-induced lung injury in rats.

The CC chemokine eotaxin is a potent and specific eosinophil chemoattractant. Eosinophil-dependent tissue injury has been shown to contribute to airway inflammation such as that in asthma. In the present study, We investigated eotaxin expression in a rat model of pulmonary inflammation (featuring accumulation of eosinophils) induced by intratracheal instillation of cross-linked dextran beads (Sephadex G200). Intratracheal instillation of 5 mg/kg Sephadex caused a time-dependent eosinophil infiltration into the lung, reaching a peak at 24 hours. Eotaxin mRNA in the lung paralleled the eosinophil influx. Eotaxin protein in bronchoalveolar (BAL) fluids and lung homogenates was shown by Western blot and immunostaining to be maximally expressed by 24 hours. Sephadex-induced lung injury, as measured by (125)I-labeled albumin leakage from the pulmonary vasculature, developed in a time-dependent manner. Intravenous injection of blocking antibody to eotaxin significantly decreased eosinophil infiltration and lung permeability. These data suggest that, in the Sephadex model of lung inflammation, eotaxin up-regulation mediates intrapulmonary accumulation of eosinophils and the development of lung injury.

Animals↗

PubMed1999

Secretory leukocyte protease inhibitor in mice regulates local and remote organ inflammatory injury induced by hepatic ischemia/reperfusion.

BACKGROUND & AIMS: This study identified and characterized the hepatic expression of secretory leukocyte protease inhibitor (SLPI) during hepatic ischemia and reperfusion in mice. In addition, the effects of exogenously administered and endogenous SLPI on liver and lung injury induced by hepatic ischemia and reperfusion were evaluated. METHODS: C57BL/6 mice underwent 90 minutes of partial hepatic ischemia and 4 hours of reperfusion in the presence or absence of exogenous SLPI or neutralizing antibodies to SLPI. RESULTS: Intravenous infusion of SLPI reduced liver and lung damage and diminished neutrophil accumulation in both organs. These effects were accompanied by reduced serum levels of tumor necrosis factor (TNF)-alpha and the CXC chemokine macrophage inflammatory protein (MIP)-2. SLPI also suppressed activation of the transcription factor NF-kappaB in liver. Hepatic ischemia and reperfusion caused increased expression of SLPI messenger RNA and SLPI protein, which was found in hepatocytes. Treatment of mice with anti-SLPI enhanced serum levels of TNF-alpha and MIP-2 and increased hepatic neutrophil accumulation and amount of liver injury. CONCLUSIONS: These data indicate that SLPI has protective effects against hepatic ischemia/reperfusion injury and suggest that endogenous SLPI functions to regulate the hepatic inflammatory response.

Animals↗

PubMed1999

Role of chemotactic factors in neutrophil activation after thermal injury in rats.

Acute thermal trauma is well known to produce evidence of a "systemic inflammatory response" in vivo, as manifested by evidence of complement activation, appearance in plasma of a variety of inflammatory factors, and development of multi-organ injury. The current studies were focused on acute thermal injury of rat skin and factors responsible for accompanying activation of blood neutrophils. Acute thermal injury of rat skin resulted in a time-dependent loss of L-selectin and up-regulation of Mac-1 (CD11b/CD18) on blood neutrophils, with no changes in LFA-1 (CD11a/CD18). The loss of L-selectin was prevented by blockade of C5a but not by blockade of the alpha-chemokine, macrophage inflammatory protein-2 (MIP-2). C5a, the alpha chemokines, MIP-2 and keratinocyte-derived cytokine (KC), and platelet activating factor (PAF) contributed to up-regulation of blood neutrophil Mac-1. Blocking interventions against these mediators also blunted the degree of neutropenia developing after thermal trauma. These data suggest that activation of blood neutrophils after thermal trauma is related to the role of several chemotactic mediators. These studies may provide clues regarding factors responsible for development of the "systemic inflammatory response syndrome" after thermal injury in the experimental model employed.

Animals↗

PubMed1999

Protective effects of C5a blockade in sepsis.

Sepsis in humans is a difficult condition to treat and is often associated with a high mortality rate. In this study, we induced sepsis in rats using cecal ligation and puncture (CLP). In rats depleted of the complement factor C3, CLP led to very short survival times (about 4 days). Of the rats that underwent CLP ('CLP rats') that were C3-intact and treated with preimmune IgG, most (92%) were dead by 7 days. Blood neutrophils from these rats contained on their surfaces the powerful complement activation product C5a. This group had high levels of bacteremia, and their blood neutrophils when stimulated in vitro had greatly reduced production of H2O2, which is known to be essential for the bactericidal function of neutrophils. In contrast, when companion CLP rats were treated with IgG antibody against C5a, survival rates were significantly improved, levels of bacteremia were considerably reduced, and the H2O2 response of blood neutrophils was preserved. Bacterial colony-forming units in spleen and liver were very high in CLP rats treated with preimmune IgG and very low in CLP rats treated with IgG antibody against C5a, similar to values obtained in rats that underwent 'sham' operations (without CLP). These data indicate that sepsis causes an excessive production of C5a, which compromises the bactericidal function of neutrophils. Thus, C5a may be a useful target for the treatment of sepsis.

Amino Acid Sequence↗