Search PubMed⌕ Search

Biomedical subjects

Alfred Ayala

Publications and source records attributed to Alfred Ayala.

At least 37 records · Page 2Linked to original sources
PubMed2004

Polymicrobial sepsis induces divergent effects on splenic and peritoneal dendritic cell function in mice.

Dendritic cells (DCs) are professional antigen-presenting cells that act as sentinels in the cell-mediated response against invading pathogens associated with septic challenge. The purpose of the present study was to determine whether there is a loss of dendritic cells and/or changes in function of these cells in septic mice. Here we report that the number of DCs, in both spleen and peritoneum, decreased over 24 h postsepsis [cecal ligation and puncture (CLP)] when compared with sham. The most dramatic change was seen in the peritoneal cavity. This decrease appeared to be caused mainly by the depletion of immature DCs rather than mature DCs. This change was LPS independent and minimally affected by FasL; however, overexpression of human Bcl-2 gene provides protection of the septic peritoneal DCs. Moreover, although the level of IL-12 release decreased significantly in splenic DCs obtained from CLP mice, IL-12 secretion was markedly elevated by peritoneal DCs as well as in both plasma and peritoneal fluid at 24 h post-CLP. In peritoneal cells, the expression of CD40, CD80, and CD86 was unchanged, but their respective ligands CD40L, CD28, and CD152 all increased in mice 24 h after CLP, although no such change was observed in splenocytes. Regardless of the presence or absence of antigen, peritoneal DCs from CLP mice showed higher capacity to stimulate T-cell proliferation than those cells from the sham control. However, splenic DCs from CLP mice only showed augmented capacity to induce antigen-dependent stimulation of T-cell proliferation. Together, these data indicate that sepsis produces divergent functional changes in splenic and peritoneal DC populations.

Animals↗
PubMed2004

Putative mechanism of hemorrhage-induced leukocyte hyporesponsiveness: induction of suppressor of cytokine signaling-3.

BACKGROUND: After hemorrhagic shock, macrophages are less responsive to lipopolysaccharide (LPS) regarding cytokine production and receptor expression. However, mechanisms responsible for this are poorly understood. Suppressors of cytokine signaling (SOCS) proteins have been found to play a prominent role in LPS tolerance and cytokine desensitization in macrophages. Therefore, the purpose of this study was to determine whether hemorrhagic shock induced SOCS expression. METHODS: Male C3H/HeN mice were subjected to hemorrhage or sham hemorrhage. Twenty-four hours after each procedure, tissues were harvested, the cells were processed for protein, and SOCS expression was examined. RESULTS: Our data show that SOCS-1 expression does not change after hemorrhage, but SOCS-3 is up-regulated in a tissue and cell population (e.g., macrophage)-specific manner. CONCLUSION: These data suggest that cytokines or other inflammatory mediators present during the first 24 hours after the induction of shock have the ability to induce tolerance to LPS or cytokines and suppress the function of immune cells by up-regulating SOCS-3.

Animals↗
PubMed2003

On-pump coronary artery bypass surgery activates human myocardial NF-kappaB and increases TNF-alpha in the heart.

PURPOSE: Myocardial tumor necrosis factor alpha (TNF) production and nuclear factor kappa B (NF-kappaB) activation has been demonstrated in chronic heart failure and experimental models of acute ischemia-reperfusion injury. Further, a cause and effect relationship has been established between these events and cardiomyocyte apoptosis following such conditions. It remains unknown, however, whether the myocardial injury associated with coronary artery bypass surgery (CAB) results in myocardial NF-kappaB activation and TNF production. We hypothesized that CAB with cardiopulmonary bypass ("on-pump") activates human myocardial NF-kappaB and increases TNF in the heart. METHODS: Patients, 18 to 65 years of age, scheduled for elective cardiac surgery but without other preexisting disease were considered eligible for the study. Biopsies of human myocardium were obtained before and after cardiopulmonary bypass and myocardial TNF levels were determined by ELISA and cytotoxicity assay, and NF-kappaB activation was determined by electrophoretic mobility shift assay (n = 6 patients). NF-kappaB activation was quantitated with gel densitometry. RESULTS: The clinical characteristics of the study patients were as follows (means +/- SEM): mean age (y) 50.0 +/- 5.7, male 6 (100%), cardiopulmonary bypass time (min) 107 +/- 37.7, cross-clamp time (min) 68 +/- 17.6, number of CAB 3.0 +/- 1.1, and length of hospital stay (d) 4.8 +/- 0.9. Before CAB, myocardial TNF-alpha levels were 251 +/- 22 pg/g and 33 +/- 9 U/g, as determined by ELISA and cytotoxicity assay, respectively. Following CAB, human myocardial TNF-alpha levels increased to 892 +/- 71 pg/g (P = 0.0008) and 141 +/- 11 U/g (P = 0.0042), as determined by ELISA and cytotoxicity assay, respectively. Before CAB, the ratio of bound to unbound NF-kappaB DNA was 0.009 +/- 0.0007 and after CAB the ratio was 0.24 +/- 0.01 (P < 0.0001). CONCLUSIONS: This study represents the initial demonstration that coronary artery bypass grafting results in an activation of NF-kappaB and an increase of TNF in the heart.

Cardiopulmonary Bypass↗
PubMed2003

Inhibition of CD1d activation suppresses septic mortality: a role for NK-T cells in septic immune dysfunction.

BACKGROUND: Studies indicate that following septic insult there is development of generalized immune dysfunction in T cells, B cells and phagocytes, which is thought to contribute to morbidity and mortality. Specifically, there is a shift in the lymphocytes of septic animals toward an increased release of Th2 cytokines. NK-T cells have been shown to contribute to propagation of the Th2 response. The influence of NK-T cells on the immune response to septic challenge is poorly understood. In this study, we examine whether NK-T cells contribute to the immune dysfunction seen following the onset of polymicrobial sepsis, as produced by cecal ligation and puncture (CLP). MATERIALS AND METHODS: Male 129S1/SvImJ mice were pretreated with either rat IgG (isotypic control) or monoclonal antibody to CD1d (clone 1B1) (0.5 mg), which blocks signaling/antigen presentation via the CD1d cell surface receptor, thereby, ablating the activation and differentiation of the NK-T cells. Septic survival with and without anti-CD1d (CLP/CD1d) pretreatment was assessed. Mice sacrificed 24 h after CLP were assessed for change in splenic %NK-T cell (via flourescense activated cell sector) and for splenic, hepatic, and lymphoid/macrophage production of pro-inflammatory or anti-inflammatory cytokines (via enzyme-linked immunosorbent assay). RESULTS: Administration of anti-CD1d reduced septic mortality 35% at 6-10 d (n = 23 mice/group) (P <.05). There was a consistent increase in the %CD3(+) NK1.1(+) cell population (NK-T cells) in septic mice (1.706%), which was markedly suppressed by pretreatment with anti-CD1d (0.592%). IL-6 and IL-10 levels were suppressed by anti-CD1d in the spleen and blood. CONCLUSIONS: Together these findings imply not only that NK-T cells may play a role in mediating the immune suppression seen in bacterial sepsis, but that inhibition of their activation promotes survival to septic challenge.

Animals↗
PubMed2003

Pathological aspects of apoptosis in severe sepsis and shock?

Today, despite the application of contemporary operative/pharmacological approaches in the treatment of the critically ill trauma/surgery patient, we are still faced with a high incidence of patients who develop sepsis and subsequent multiple organ failure. This review attempts to summarize data gathered over the last few years, from both experimental and patient settings, that not only documents the presence of apoptosis, but begins to define its contribution to the pathology of sepsis and shock, which in turn precipitate organ injury/damage.

Animals↗
PubMed2003

Differential effects of macrophage inflammatory chemokine-2 and keratinocyte-derived chemokine on hemorrhage-induced neutrophil priming for lung inflammation: assessment by adoptive cells transfer in mice.

Prior studies have shown that hemorrhage (Hem) can serve as a priming stimulus for acute lung injury (ALI) triggered by subsequent septic challenge (cecal ligation and puncture, CLP). Furthermore, we have reported that in vivo antibody neutralization of the chemokines, macrophage inflammatory chemokine-2 (MIP-2) and keratinocyte-derived chemokine (KC), immediately after Hem appears to differentially effect the onset of ALI. However, although we hypothesize that this is due to divergent effects of MIP-2 and KC on Hem-induced neutrophil (PMN) priming, this has not been tested. To examine this hypothesis, PMN donor mice were Sham-Hem or Hem for 90 min at 35 +/- 5 mmHg and were then administered anti-MIP- 2 (Hem/anti-MIP2), anti-KC (Hem/anti-KC), or nonspecific immunoglobulin (Ig) G (Hem/IgG) during resuscitation (Ringer's lactate = four times the amount of drawn blood volume). Twenty-four hours post-Hem, the peripheral blood PMN were purified from these donor animals and were introduced into PMN-depleted recipient mice [depleted by prior anti-Gr1 (mouse PMN-specific marker) antibody treatment]. One hour after PMN transfer, recipient mice were subjected to CLP, euthanized 24 h later, and plasma as well as lung tissue samples were collected. PMN influx was assessed by myeloperoxidase assay (MPO; microU/mg protein) and histologically (IL-6, MIP-2, KC, and IL-10 levels) by enzyme-linked immunoabsorbant assay (ELISA; ng/mg). The results show that donor PMN from Hem/IgG but not Sham-Hem mice produce increased PMN influx (increased MPO, increased % esterase+ cells in tissue) into the lung and local tissue inflammation (increased IL-6/MIP-2, decreased IL-10) in PMN-depleted CLP recipient mice, which was attenuated in mice receiving cells from Hem/anti-MIP-2 but not Hem/anti-KC treated donors. Interestingly, although Hem/anti-MIP-2 donor PMN produced comparable effects on blood IL-6/MIP-2 levels, they were ineffective in altering the change in plasma IL-10/KC levels induce by Hem. Taken together, these data demonstrate that Hem-induced priming of PMN not only mediates ALI in the mouse, but also that this process is differentially effected by MIP2 and KC, despite the fact that both signal through CXCR2.

Adoptive Transfer↗
PubMed2003

Mechanisms of immune resolution.

Initially after injury, the innate/proinflammatory and some aspects of the acquired immune response are up-regulated to maintain a defense against foreign pathogens, clear tissue debris present at the wound site, and orchestrate aspects of tissue remodeling, cell proliferation and angiogenic process, associated with the wound response. However, for proper wound healing to progress, this initial inflammatory response has to be regulated or shut down so as to allow for the reestablishment of matrix, recellularization, and tissue remodeling. Inability to properly resolve the extent of innate/acquired response at a site of injury can lead to poor wound healing, immune suppression, and recurrent infectious episodes. This review attempts to summarize information on regulatory mechanisms that are thought to be involved in controlling/resolving innate or acquired immune responses so as to provide a framework for use in thinking about the impact these processes and their manipulation may have on wound healing and its potential management.

Animals↗
PubMed2003

Sex-specific p38 MAP kinase activation following trauma-hemorrhage: involvement of testosterone and estradiol.

Although immune functions are markedly depressed in males and not in proestrous females following trauma-hemorrhage (T-H), the mechanisms responsible for the divergent responses remain unknown. Because sex steroids modulate the activation of p38, our aim was to determine whether differences in the activation of p38 by phosphorylation (p38-P) might contribute to the sex-dimorphic immune response following T-H. The effects of testosterone and estradiol on the activation of p38 were also examined. Intact male mice (C3H/HeN), castrated males treated with vehicle, 5alpha-dihydrotestosterone (DHT), or 17beta-estradiol, and proestrous females were subjected to trauma (i.e., midline laparotomy) and hemorrhagic shock (35 +/- 5 mmHg for 90 min and resuscitation) or sham operation. At 2 h thereafter, splenic (SMphi) and peritoneal macrophages (PMphi) were harvested and cultured (with 10 microg/ml LPS), and Western blot analysis was carried out for quantification of p38 and p38-P. Sex, testosterone and estradiol plasma levels, and T-H did not alter the constitutive expression of p38 in SMphi and PMphi. In contrast, the activated form of p38 (p38-P) was markedly increased in SMphi and PMphi from female shams compared with male shams. Moreover, the phosphorylation of p38-P increased in males after T-H, whereas it decreased in females under those conditions. Castration before T-H prevented the increase in p38-P in males. Castrated animals treated with DHT displayed increased p38-P following T-H, whereas 17beta-estradiol had no effect on p38-P in castrated mice. Thus 1) sex influences the activation of p38 MAP kinase, 2) DHT is responsible for the increased activation of p38 in male mice, and 3) this sex-specific activation of p38 might be responsible for the sexually dimorphic immune response following T-H.

Animals↗
PubMed2003

Inhibition of Fas/Fas ligand signaling improves septic survival: differential effects on macrophage apoptotic and functional capacity.

Signaling through the Fas/Fas ligand (FasL) pathway plays a central role in immune-cell response and function; however, under certain pathological conditions such as sepsis, it may contribute to the animal's or patient's morbidity and mortality. To determine the contribution of FasL to mortality, we conducted survival studies by blocking Fas/FasL with Fas receptor fusion protein (FasFP) in vivo. C3H/HeN mice received FasFP or the saline vehicle (veh) immediately (0 h) or delayed (12 h), after sepsis induced by cecal ligation and puncture (CLP). Subsequently, we examined the effect of FasFP treatment (12 h post-CLP) on macrophage apoptosis and functional capacities. Peritoneal and splenic macrophages and Kupffer cells from sham-veh-, CLP-veh-, sham-FasFP-, or CLP-FasFP-treated mice were harvested 24 h after CLP and stimulated with lipopolysaccharide (LPS) for 24 h. The results indicate that only delayed (12 h) but not 0 h administration of FasFP demonstrated a significant increase in survival. The ability of all macrophage populations to release interleukin (IL)-6 was significantly depressed, and IL-10 release was augmented after CLP. FasFP treatment attenuated the increased IL-10 release in Kupffer cells. However, althogh enhanced susceptibility to LPS-induced apoptosis could be suppressed in CLP mouse Kupffer cells by FasFP, FasFP did not change the peritoneal or splenic macrophage response. Furthermore, FasFP attenuated the elevated plasma levels of liver enzymes after sepsis. These data indicate that in vivo inhibition of Fas/FasL signaling has tissue-specific effects on the induction of macrophage apoptosis, functional changes, and liver damage, which may contribute to the host's ability to ward off a septic challenge.

Animals↗
PubMed2003

Fas-ligand mediated apoptosis in severe sepsis and shock.

Alterations in the apoptotic process in lymphoid tissues is a common condition which is encountered in the severely septic animal and critically ill patient. Here we attempt to delineate the pathological significance of these apoptotic changes and the role of Fas-FasL mediated contribution to this process.

Animals↗
PubMed2002

Shock-induced neutrophil mediated priming for acute lung injury in mice: divergent effects of TLR-4 and TLR-4/FasL deficiency.

Acute lung injury (ALI) leading to respiratory distress is a common sequela of shock/trauma, however, modeling this process in mice with a single shock or septic event is inconsistent. One explanation is that hemorrhage is often just a "priming insult," thus, secondary stimuli may be required to "trigger" ALI. To test this we carried out studies in which we assessed the capacity of hemorrhage alone or hemorrhage followed by septic challenge (CLP) to induce ALI. Lung edema, bronchoalveolar lavage interleukin (IL)-6, alveolar congestion, as well as lung IL-6, macrophage inflammatory protein (MIP)-2, and myeloperoxidase (MPO) activity were all increased in mice subjected to CLP at 24 but not 72 hours following hemorrhage. This was associated with a marked increase in the susceptibility of these mice to septic mortality. Peripheral blood neutrophils derived from 24 hours post-hemorrhage, but not Sham animals, exhibited an ex vivo decrease in apoptotic frequency and an increase in respiratory burst capacity, consistent with in vivo "priming." Subsequently, we observed that adoptive transfer of neutrophils from hemorrhaged but not sham-hemorrhage animals to neutropenic recipients reproduce ALI when subsequently septically challenged, implying that this priming was mediated by neutrophils. We also found marked general increases in lung IL-6, MIP-2, and MPO in mice deficient for toll-like receptor (TLR-4) or the combined lack of TLR-4/FasL. However, the TLR-4 defect markedly attenuated neutrophil influx into the lung while not altering the change in local cytokine/chemokine expression. Alternatively, the combined loss of FasL and TLR-4 did not inhibit the increase in MPO and exacerbated lung IL-6/MIP-2 levels even further.

Animals↗
PubMed2002

Female sex hormones regulate macrophage function after trauma-hemorrhage and prevent increased death rate from subsequent sepsis.

OBJECTIVE: To determine whether reduction of circulating female sex hormones by ovariectomy causes suppression of macrophage (Mphi) function after trauma-hemorrhage and increases susceptibility to subsequent sepsis. SUMMARY BACKGROUND DATA: Studies indicate that immune functions are markedly depressed in males but not in proestrus females after trauma-hemorrhage. Although male sex steroids are immunosuppressive, it remains unknown whether female sex hormones are immunoprotective after trauma-hemorrhage. METHODS: Circulating female sex hormones were reduced by ovariectomy of 8-week-old female CBA/J mice. Two weeks afterward, ovariectomy and proestrus sham-ovariectomy mice were subjected to laparotomy (i.e., soft tissue trauma) and hemorrhagic shock (35 +/- 5 mm Hg for 90 minutes, then resuscitated) or sham operation. Two hours afterward, splenic and peritoneal Mphi and Kupffer cells were isolated and cytokine production was assessed. In a second series of experiments, animals were subjected to sepsis by cecal ligation and puncture at 24 hours after trauma-hemorrhage or sham operation, and survival was assessed. RESULTS: Release of interleukin-1 and interleukin-6 by splenic and peritoneal Mphi from proestrus mice was maintained after trauma-hemorrhage, whereas release of interleukin-1 and interleukin-6 by Mphi from ovariectomized mice was depressed by approximately 50%. In contrast, trauma-hemorrhage resulted in a fourfold increase of Kupffer cell release of tumor necrosis factor-alpha in ovariectomized females and a fivefold increase in plasma concentrations of tumor necrosis factor-alpha. Release of tumor necrosis factor-alpha and plasma concentrations were unchanged in proestrus mice under such conditions. When proestrus and ovariectomized animals were subjected to sepsis by cecal ligation and puncture at 24 hours after trauma-hemorrhage or sham operation, ovariectomized mice had a significantly higher death rate than proestrus mice. CONCLUSIONS: These findings suggest that female sex hormones play a critical role in maintaining immune responses after trauma-hemorrhage by suppressing the elaboration of tumor necrosis factor-alpha and prevent the increased lethality from subsequent sepsis. Thus, female sex hormones may be a useful adjunct in preventing trauma-induced immunodepression and increased susceptibility to subsequent sepsis.

Analysis of Variance↗
PubMed2002

Tumor necrosis factor-alpha-stimulated polymorphonuclear leukocytes suppress migration and bactericidal activity of polymorphonuclear leukocytes in a paracrine manner.

OBJECTIVE: Polymorphonuclear leukocytes (PMN) and tumor necrosis factor-alpha (TNF-alpha) play prominent roles in acute respiratory distress syndrome, ischemia-reperfusion injury, trauma, and sepsis. Whereas direct effects of TNF-alpha on PMN function and viability are well documented, little data are available addressing the ability of PMN to communicate with each other in response to cytokine stimulation. Therefore, the aim of this study was to determine whether TNF-alpha can modulate PMN function by inducing PMN to secrete products upon stimulation, which would affect other PMN in vitro in a manner independent of cell contact. METHODS: PMN were purified daily from blood obtained from a pool of 22 healthy volunteers. Conditioned media (CM-TNF) was prepared by incubating PMN in Hanks' balanced salt solution plus TNF-alpha for 1-4 hrs. Freshly isolated PMN were resuspended in CM-TNF and analyzed for 1) phagocytosis of opsonized Escherichia coli, 2) oxidative metabolism as measured as an index of DCF-DA activation, and 3) migration to chemoattractants through Transwell inserts. RESULTS: CM-TNF decreased PMN phagocytotic activity by 8% to 15% and completely suppressed oxidative metabolism but did not modulate the expression of receptors associated with these functions. CM-TNF suppressed the migration of PMN to two biologically relevant agents, N-formyl-methionyl-leucyl-phenylalanine and leukotriene B4, by approximately 65%, but had no effect on PMN migration to interleukin-8. This suppression was observed for migration across plastic filters as well as extracellular matrix proteins. CONCLUSION: Our data demonstrate that PMN stimulated with TNF-alpha suppress the immunologic function and migration of other PMN independent of cell-cell contact and suggest that TNF-alpha may participate in a negative feedback loop by inducing a PMN-derived factor that counteracts its activity.

Analysis of Variance↗
PubMed2002

Mechanism of immune dysfunction in sepsis: inducible nitric oxide-meditated alterations in p38 MAPK activation.

BACKGROUND: After the onset of sepsis, there is a marked dysfunction in cell-mediated immunity that contributes to the morbidity and mortality seen in this condition. Although both nitric oxide (NO) from inducible NO synthase (iNOS) and the activation of p38 mitogen-activated protein kinase (p38 MAPK) appear to contribute to this immune dysfunction, the extent to which NO regulates p38 MAPK activity in sepsis remains unknown. METHODS: To examine this, we induced sepsis by cecal ligation and puncture (CLP) in iNOS knockout (iNOS -/-) or C57BL/6 control mice. Twenty-four hours after CLP or sham operation, splenic T cells and macrophages were isolated and then stimulated with monoclonal antibody against the T-cell marker CD3 (anti-CD3) or lipopolysaccharide. At 4 or 24 hours after stimulation, cytokine release was determined by enzyme-linked immunosorbent assay, and p38 MAPK phosphorylation (activation) was determined by immunoblotting with antibody specific to phosphorylated p38 MAPK. RESULTS: Splenic T-cell p38 MAPK activation and interleukin (IL)-10 release was increased by CLP, whereas Th1 cytokine (IL-2, interferon-gamma) release was depressed. iNOS gene deficiency inhibited p38 MAPK activation in splenic T cells taken from septic mice, and also suppressed IL-10 release in both sham and septic mice. Interestingly, although deficiency of iNOS restored IL-2 release after CLP, both sham and CLP T cells remained depressed in their ability to release interferon-gamma. Septic insult markedly suppressed C57BL/6 splenic macrophage release of proinflammatory agents tumor necrosis factor, IL-12, and IL-1, while augmenting the release of IL-10. However, although deficiency of iNOS concomitantly restored the ability to produce tumor necrosis factor while suppressing the rise in IL-10 release and p38 MAPK activation, it only partially restored IL-1 release and had no effect on IL-12 production seen after CLP. CONCLUSION: These data suggest that NO release from iNOS regulates aspects of sepsis-induced immune dysfunction by the activation of p38 MAPK.

Animals↗
PubMed2002

Paracrine suppression of apoptosis by cytokine-stimulated neutrophils involves divergent regulation of NF-kappaB, Bcl-X(L), and Bak.

Dysregulated polymorphonuclear leukocyte (PMN) apoptosis and PMN-mediated organ damage have been associated with several medical conditions such as systemic inflammatory response syndrome (SIRS), acute respiratory distress syndrome (ARDS), and ischemia/reperfusion injury. IL-1beta and IL-8 are two cytokines that are elevated under similar conditions. Therefore, we hypothesized that PMN exposed to these cytokines would secrete factors that could affect PMN apoptosis in a cell contact-independent manner. We have previously shown that media conditioned by IL-1beta-stimulated PMN (CM-IL1beta) for 2 h suppressed spontaneous PMN apoptosis. Data presented here demonstrate that media conditioned by IL-8-stimulated PMN (CM-IL8) also have the ability to suppress spontaneous, as well as FasL- and TNF-alpha-induced apoptosis. In contrast, CM-IL1beta was able to suppress FasL-induced, but not TNF-alpha-induced, apoptosis. To elucidate the mechanisms these media use to elicit their effects, we examined the expression and function of several apoptosis-related proteins. Experimental results demonstrate that both CM-IL1beta and CM-IL8 have the ability to delay caspase activation, but have no effect on the expression of their upstream activator, Fas, or its ligand, FasL. Examination of several Bcl-2 family members revealed a selective regulation by each media: CM-IL1beta up-regulated Bcl-X(L), while CM-IL8 down-regulated Bak expression. Additionally, CM-IL1beta, but not CM-IL8, promoted the activation of NF-kappaB, which has anti-apoptotic activity. Together, we can conclude that IL-1beta- and IL-8-stimulated PMN have the ability to suppress PMN apoptosis in a paracrine manner, and that the extent and mechanism of suppression is specific for each.

Apoptosis↗
PubMed2002

Differential alterations in cardiovascular responses during the progression of polymicrobial sepsis in the mouse.

Although the mouse has been extensively used to study immune consequences of sepsis and other genetic anomalies, the changes in various cardiovascular parameters such as cardiac output, organ perfusion, as well as oxygen utilization have not been characterized in this species during sepsis. To determine this, polymicrobial sepsis was induced in male adult C3H/NeN mice by cecal ligation and puncture (CLP, two punctures with a 22-gauge needle). The animals were then resuscitated with normal saline subcutaneously. At 5 or 24 h after CLP (time points previously shown to be within the hyperdynamic and hypodynamic stage of sepsis, respectively, in the rat), cardiac output and blood flow in major organs were determined using a well-established radioactive microsphere method, and stroke volume and total peripheral resistance were calculated. In addition, oxygen delivery and consumption were determined. The results indicate that cardiac output, stroke volume, oxygen delivery and consumption, and blood flow in the liver, small intestine, spleen, and kidneys increased significantly at 5 h after CLP. This was associated with significantly decreased total peripheral resistance. In contrast, total peripheral resistance increased and the other above-mentioned parameters, as well as mean arterial pressure, decreased significantly at 24 h after the onset of sepsis. Thus, the cardiovascular response to polymicrobial sepsis in the mouse is characterized by an early hyperdynamic phase (i.e., 5 h after CLP) followed by a late hypodynamic phase (24 h post-CLP). Since the radioactive microsphere technique provides a reliable method for determining various hemodynamic parameters in the mouse, the correlation between the cardiovascular response and immune or potentially genetic alterations can be examined in this species during the progression of sepsis.

Animals↗
PubMed2002

NF-kappaB activation has tissue-specific effects on immune cell apoptosis during polymicrobial sepsis.

Studies indicate that critically ill patients who succumb to sequela of sepsis/multiorgan failure, as well as septic animals, exhibit an apparently pathological increase in apoptosis (Ao) in the immune system. However, the mechanisms regulating these changes are unclear. Studies also indicate that, dependent on the cell population and the nature and/or duration of the stimuli, activation of the nuclear factor (NF)-kappaB can either suppress or enhance Ao. Thus, the aim of this study was to determine the contribution of NF-kappaB activation to the onset of Ao seen in divergent immune cell populations during sepsis, as produced by cecal ligation and puncture (CLP). To assess this, C3H/HeN mice were pretreated (for 1 h) subcutaneously with either 100 mg/kg body weight of pyrrolidine dithiocarbamate (PDTC), an NF-kappaB inhibitor, or with saline vehicle, prior to subjecting them to CLP or Sham-CLP (Sham). Thymocytes, phagocytes, and Peyers Patch cells were harvested 24 h later, and the extent of Ao was determined by flow cytometry. The results indicate that PDTC pretreatment had no marked effect on the increase in thymocyte or phagocyte Ao seen following CLP, but there was a significant decline in the extent of Ao observed in septic mouse Peyer's patch B cells. To the extent that this was a result of NF-kappaB inhibition, we demonstrate by Western analysis, electrophoretic mobility shift assay (EMSA) and transfactor assay that the translocation of c-Rel to septic mouse Peyer's patch B cell nuclei is attenuated by PDTC. PDTC pretreatment also markedly reduced the number of Peyer's patch B cells that were producing IgA as well as attenuated the increase of proinflammatory cytokines in the blood. Interestingly, PDTC pretreatment did not restore peritoneal macrophage function or improve animal survival. Taken together, the inability of PDTC pretreatment to alter the Ao response of thymocytes or phagocytes, while inhibiting the increase in Peyer's patch B cell Ao in septic mice, implies not only that the activation of NF-kappaB has highly tissue/cell-specific effects that must be discerned when trying to clarify the pathophysiological role of NF-kappaB in sepsis, but that the activation of NF-kappaB may contribute to the early adaptive responses required by the host to fend off septic challenge.

Animals↗