Lymphocytes in the development of lung inflammation: a role for regulatory CD4+ T cells in indirect pulmonary lung injury

Although roles for myelocytes have been suggested in the pathophysiology of indirect acute lung injury (ALI not due to a direct insult to the lung), the contribution of various regulatory lymphoid subsets is unknown. We hypothesized a role for lymphocytes in this process. Using a sequential model of indirect ALI induced in mice by hemorrhagic shock followed 24 h later by polymicrobial sepsis; we observed a specific and nonredundant role for each lymphocyte subpopulation in indirect ALI pathophysiology. In particular, we showed that CD4(+) T cells are specifically recruited to the lung in a dendritic cell-independent but IL-16-dependent process and diminish neutrophil recruitment through increased IL-10 production. Most importantly, this appears to be mediated by the specific subpopulation of CD4(+)CD25(+)Foxp3(+) regulatory T cells. Although indirect ALI has constantly been described as a proinflammatory pathology mediated by cells of the innate immune system, we now demonstrate that cells of the adaptive immune response play a major role in its pathophysiology as well. Most importantly, we also describe for the first time the nature of the regulatory mechanisms activated in the lung during indirect ALI, with CD4(+) regulatory T cells being central to the control of neutrophil recruitment via increased IL-10 production.

The role of hepatic invariant NKT cells in systemic/local inflammation and mortality during polymicrobial septic shock

NKT cells have been described as innate regulatory cells because of their rapid response to conserved glycolipids presented on CD1d via their invariant TCR. However, little is known about the contribution of the hepatic NKT cell to the development of a local and/or systemic immune response to acute septic challenge (cecal ligation and puncture (CLP)). We found not only that mice deficient in invariant NKT cells (Jalpha18(-/-)) had a marked attenuation in CLP-induced mortality, but also exhibited an oblation of the systemic inflammatory response (with little effect on splenic/peritoneal immune responsiveness). Flow cytometric data indicated that following CLP, there was a marked decline in the percentage of CD3(+)alpha-galactosylceramide CD1d tetramer(+) cells in the mouse C57BL/6J and BALB/c liver nonparenchymal cell population. This was associated with the marked activation of these cells (increased expression of CD69 and CD25) as well as a rise in the frequency of NKT cells positive for both Th1 and Th2 intracellular cytokines. In this respect, when mice were pretreated in vivo with anti-CD1d-blocking Ab, we observed not only that this inhibited the systemic rise of IL-6 and IL-10 levels in septic mice and improved overall septic survival, but that the CLP-induced changes in liver macrophage IL-6 and IL-10 expressions were inversely effected by this treatment. Together, these findings suggest that the activation of hepatic invariant NKT cells plays a critical role in regulating the innate immune/systemic inflammatory response and survival in a model of acute septic shock.

CD4+ lymphocytes control gut epithelial apoptosis and mediate survival in sepsis

Lymphocytes help determine whether gut epithelial cells proliferate or differentiate but are not known to affect whether they live or die. Here, we report that lymphocytes play a controlling role in mediating gut epithelial apoptosis in sepsis but not under basal conditions. Gut epithelial apoptosis is similar in unmanipulated Rag-1(-/-) and wild-type (WT) mice. However, Rag-1(-/-) animals have a 5-fold augmentation in gut epithelial apoptosis following cecal ligation and puncture (CLP) compared to septic WT mice. Reconstitution of lymphocytes in Rag-1(-/-) mice via adoptive transfer decreases intestinal apoptosis to levels seen in WT animals. Subset analysis indicates that CD4(+) but not CD8(+), gammadelta, or B cells are responsible for the antiapoptotic effect of lymphocytes on the gut epithelium. Gut-specific overexpression of Bcl-2 in transgenic mice decreases mortality following CLP. This survival benefit is lymphocyte dependent since gut-specific overexpression of Bcl-2 fails to alter survival when the transgene is overexpressed in Rag-1(-/-) mice. Further, adoptively transferring lymphocytes to Rag-1(-/-) mice that simultaneously overexpress gut-specific Bcl-2 results in improved mortality following sepsis. Thus, sepsis unmasks CD4(+) lymphocyte control of gut apoptosis that is not present under homeostatic conditions, which acts as a key determinant of both cellular survival and host mortality.

Increased circulating regulatory T cells (CD4(+)CD25 (+)CD127 (-)) contribute to lymphocyte anergy in septic shock patients

PURPOSE

Sepsis syndrome represents the leading cause of death in intensive care unit. Patients present features consistent with a decline in immune responsiveness potentially contributing to mortality. We investigated whether CD4(+)CD25(+) regulatory T cells (Treg) participate in the induction of lymphocyte anergy after sepsis.

METHOD

Observational study in septic shock patients and experimental study in mice.

RESULTS

We took advantage of the recently described flow cytometric gating strategy using the measurement of CD25 and CD127 expressions for monitoring Treg (CD4(+)CD25(+)CD127(-)Foxp3(+)). In patients the increased circulating Treg percentage significantly correlated with a decreased lympho-proliferative response. In a murine model of sepsis mimicking these observations, the ex vivo downregulation of Foxp3 expression using siRNA was associated with a restoration of this response.

CONCLUSION

The relative increase in circulating Treg might play a role in lymphocyte anergy described after septic shock and represent a standardizable surrogate marker of declining proliferative capacity after sepsis.

Apoptosis in sepsis: mechanisms, clinical impact and potential therapeutic targets

The inability of present therapies to mitigate the devastating effects of sepsis and multiple organ failure in the critically ill patient indicates that more knowledge of the pathophysiology of sepsis is needed if we are to develop better, more effective interventions. This review will examine the concept that a portion of the immune and organ dysfunctions encountered in the septic rodent/ patient is a reflection of not only the types of cells stimulating/ mediating the apoptotic response, but also the varying capacity of the target cell in a given tissue/ organ to perceive these death receptor stimuli as either an apoptotic, inflammatory and/or necrotic signal. We hope the discussion of such studies provides not only new insight into the pathobiology of sepsis, but also suggests possible therapeutic targets for the management of this devastating condition.

Blockade of apoptosis as a rational therapeutic strategy for the treatment of sepsis

Over time it has become clear that, much like other organ systems, the function and responsiveness of the immune system is impaired during the course of sepsis and that this is a precipitous event in the decline of the critically ill patient/animal. One hypothesis put forward to explain the development of septic immune dysfunction is that it is a pathological result of increased immune cell apoptosis. Alternatively, it has been proposed that the clearance of increased numbers of apoptotic cells may actively drive immune suppression through the cells that handle them. Here we review the data from studies involving septic animals and patients, which indicate that loss of immune cells, as well as non-immune cells, in some cases, is a result of dysregulated apoptosis. Subsequently, we will consider the cell death pathways, i.e. 'extrinsic' and/or 'intrinsic', which are activated and what cell populations may orchestrate this dysfunctional apoptotic process, immune and/or non-immune. Finally, we will discuss potentially novel therapeutic targets, such as caspases, death receptor family members (e.g. tumour necrosis factor, Fas) and pro-/anti apoptotic Bcl-family members, and approaches such as caspase inhibitors, the use of fusion proteins, peptidomimetics and siRNA, which might be considered for the treatment of the septic patient.

Epithelial cell apoptosis and neutrophil recruitment in acute lung injury-a unifying hypothesis? What we have learned from small interfering RNAs

In spite of protective ventilatory strategies, Acute Lung Injury (ALI) remains associated with high morbidity and mortality. One reason for the lack of therapeutic options might be that ALI is a co-morbid event associated with a diverse family of diseases and, thus, may be the result of distinct pathological processes. Among them, activated neutrophil- (PMN-) induced tissue injury and epithelial cell apoptosis mediated lung damage represent two potentially important candidate pathomechanisms that have been put forward. Several approaches have been undertaken to test these hypotheses, with substantial success in the treatment of experimental forms of ALI. With this in mind, we will summarize these two current hypotheses of ALI briefly, emphasizing the role of apoptosis in regulating PMN and/or lung epithelial cell responses. In addition, the contribution that Fas-mediated inflammation may play as a potential biological link between lung cell apoptosis and PMN recruitment will be considered, as well as the in vivo application of small interfering RNA (siRNA) as a novel approach to the inhibition of ALI and its therapeutic implications.

RNA interference as a potential therapeutic treatment for inflammation associated lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) remain important sources of morbidity for patients in the ICUs in the developed world. However, imagine having as a therapeutic tool, the ability to regulate, in a tissue specific manner, the expression of a given gene. RNA interference, as potentially such a method of selectively suppressing protein expression, has evolved as an important tool in the study of gene specific function and targeted therapeutics. Significant progress has been made in identifying potential gene targets integral to the pathways leading to the development of inflammation-associated lung injury. This review will discuss the progress, thus far, in the application of in vivo RNA interference-based gene therapy in the investigation of inflammation-associated lung injury.

Hydrodynamic delivery of siRNA in a mouse model of sepsis

The use of siRNA in vivo as well as in animal models has become more widespread in recent years, leading to further questions as to the best mode of delivery that will achieve optimal knockdown. While the exact mechanism of siRNA uptake at a cellular level has yet to be fully elucidated, various delivery techniques are being researched, including the use of viral vectors of shRNA, liposome encapsulations, and hydrodynamic delivery of naked siRNA. We describe the use of hydrodynamic administration as a technique to deliver, in vivo, naked siRNA constructs into experimental animals as a method of transient gene knockdown. This method may prove useful in situations where knockout animals do not exist, or to determine the effect of gene knockdown at specific time points during an experiment.

Severity of alcohol withdrawal symptoms depends on developmental stage of Long-Evans rats

To investigate alcohol dependency and the potential role of age of initial alcohol consumption, Long-Evans (LE) rats were fed an ethanol-containing liquid diet starting at postnatal (P) ages (days): P23-27 (juvenile), P35-45 (adolescent) or P65-97 (young adult). Severity of subsequent withdrawal symptoms was dependent on age when consumption began and on duration of alcohol consumption. Frequency of withdrawal seizures was highest for rats starting consumption as juveniles, intermediate for adolescents and lowest for adults. Normalized to body weight, alcohol consumption was significantly higher for adolescent and juvenile rats than for adults. Sprague-Dawley rats that began alcohol consumption as adolescents (P35) had a level of alcohol consumption identical to that of the adolescent LE rats but showed much lower frequency of withdrawal seizures when tested after 2, 3 and 5 weeks of alcohol consumption. Based on several indicators, the capacity of the juveniles to metabolize ethanol is equal to or exceeds that of adults. Recoveries from a single dose of ethanol (2.5 g ethanol/kg body weight) were faster for juvenile LE rats than adults. The rate of decline in blood ethanol concentration was identical for juvenile and adult rats while the corrected ethanol elimination rate was higher for juveniles. The primary isozyme of alcohol dehydrogenase (ADH) in rat liver, ADH-3, had a similar Km and higher activity in liver preparations from juveniles. In conclusion, LE rats beginning alcohol consumption as juveniles or adolescents develop a severe alcohol withdrawal syndrome that may not be attributed entirely to higher levels of consumption and was not explained by any obvious deficiencies in metabolism.

SOCS-1 is a central mediator of steroid-increased thymocyte apoptosis and decreased survival following sepsis

Suppressor of Cytokine Signaling (SOCS) proteins are recently identified inhibitors/regulators of cytokine/growth factor signaling pathways. We have previously shown that SOCS-3 is upregulated in mice after sepsis induced by cecal ligation and puncture; however, the contribution of SOCS-1 to septic morbidity and mortality is unclear. In the present study, we characterized SOCS-1 expression in different tissues and delineated putative mechanisms effecting SOCS-1 expression in thymus from septic mice. We observed no difference in SOCS-1 expression in blood, peritoneal leukocytes, lung, and spleen taken from sham or septic animals at 24 h after surgery. In contrast, SOCS-1 expression in thymus declined significantly after sepsis and this down-regulation of SOCS-1 was associated with increased thymocyte apoptosis as well as augmented Bax recruitment to the mitochondria. Administration of RU-38486, a steroid receptor antagonist, reversed the above effects in the septic thymus. Furthermore, SOCS-1+/- mice showed a significant higher mortality when compared to SOCS-1+/+ mice after sepsis. Together, these results show that sepsis increases steroid-induced thymic lymphoid cell apoptosis, which is associated with reduced SOCS-1 expression and increased Bax translocation to mitochondria. Survival data suggests that SOCS-1 protein may play an important role in sepsis.

Impact of adenomatous polyposis coli (APC) tumor supressor gene in human colon cancer cell lines on cell cycle arrest by apigenin

This research assessed the importance of the adenomatous polyposis coli (APC) tumor suppressor mutation in the ability of apigenin to induce cell cycle arrest using HT29-APC cells, which contain inducible wild-type APC under the metallothionein promoter. HT29-GAL cells, containing beta-galactosidase (GAL), were included as control. Treatment with apigenin (0, 20, 40, 60, and 80 microM) for 48 h resulted in reduction in the cell number (P < 0.05) concurrent with flow cytometry results showing a dose-dependent accumulation of cells in the G2/M phase in both HT29-APC and HT29-GAL cells without ZnCl(2) treatment. Flow cytometric analysis showed an increase (P < 0.05) in the percentage of cells in G2/M when HT29-APC cells were treated with 80 microM apigenin for 120 h. This increase was not present in HT29-APC cells when treated with both 80 microM apigenin and 100 microM ZnCl(2) for 120 h. Western blot analysis verified the induction of APC protein expression in ZnCl(2)-treated HT29-APC cells but not in ZnCl(2)-treated HT29-GAL cells. Apigenin plus ZnCl(2) treatment increased the expression of APC protein in HT29-APC cells by 50 fold above expression observed with ZnCl(2) alone. Upon induction of the APC gene with ZnCl(2) in HT29-APC cells, the percentage of apoptotic cells increased significantly (P < 0.05) after 120-h treatment. Additionally, apigenin treatment (80 microM) further increased the percentage of apopototic HT29-APC following ZnCl(2) treatment to induce wild-type APC expression. These results suggest that APC dysfunction may be critical for apigenin to induce cell cycle arrest in human colon cancer cell lines and furthermore, apigenin enhances APC expression and apoptosis in cells with wild-type APC.

Regulatory T cell populations in sepsis and trauma

Sepsis syndrome remains the leading cause of mortality in intensive care units. It is now believed that along with the body's hyperinflammatory response designated to eliminate the underlying pathogen, mechanisms are initiated to control this initial response, which can become deleterious and result in immune dysfunctions and death. A similar state of immune suppression has been described after numerous forms of severe trauma/injury. Although the evidence for immune dysfunctions after sepsis has grown, much remains to be understood about mechanisms underpinning its development and how it acts to increase the morbid state of the critically ill patient. In this context, although the majority of clinical and basic science conducted so far has focused on the roles of myeloid cell populations, the contribution of T lymphocytes and in particular, of regulatory T cells has been somewhat ignored. The studies presented here support the concept that regulatory T lymphocytes (CD4+CD25+ regulatory, gammadelta, and NK T cells) play a role in the control of immune responses and are affected by injury and sepsis. This may be related to their capacity to interact with components of the innate and adaptive immune responses and to their ability to be activated nonspecifically by bacterial products and/or cytokines and to regulate through direct cell-cell and/or soluble mediators. It is our hope that a better understanding of the mechanism through which those rare lymphocyte subsets exert such a profound effect on the immune response may help in improving our ability not only to diagnose but also to treat the critically ill individual.

Polymicrobial sepsis enhances clearance of apoptotic immune cells by splenic macrophages

BACKGROUND

Macrophage phagocytosis of apoptotic cells induces an anti-inflammatory macrophage phenotype. Immune cell apoptosis is widespread in sepsis; however, it is unknown whether sepsis alters the capacity of macrophages to clear this expanded population. We hypothesize that sepsis will enhance splenic macrophage phagocytosis of apoptotic immune cells, potentially contributing to immunosuppression.

METHODS

Sepsis was induced in C57BL/6J mice by cecal ligation and puncture (CLP). Apoptosis was induced in mouse thymocytes by dexamethasone incubation. At multiple time points after CLP/sham, splenic and peritoneal macrophages were isolated, plated on glass coverslips, co-incubated with apoptotic thymocytes, and fixed and the coverslips were then Giemsa stained. Splenic macrophages were also isolated 48 hours after CLP/sham, stained with the red fluorescent dye PKH26, and co-incubated with green fluorescent dye CFSE-stained apoptotic thymocytes and then coverslips were fixed and counterstained with DAPI. The macrophage phagocytic index (PI) was calculated for both staining methods.

RESULTS

The PI of CLP splenic macrophages was significantly higher than sham by 24 hours, and this difference was sustained through 48 hours.

CONCLUSIONS

Studies suggest that apoptotic cell clearance leads to an anti-inflammatory macrophage condition, which together with our findings in septic macrophages, may point at a process that contributes to septic immune suppression.

Changes in dendritic cell function in the immune response to sepsis. Cell- & tissue-based therapy

Sepsis represents a complex clinical syndrome of significant morbidity and mortality. This continues to be the case in intensive care units around the world, despite extensive use of antibiotics, aggressive surgical intervention and optimization of nutritional support. Furthermore, the failure of > 30 anti-inflammatory mediator therapeutic trials implies, beyond the issue of trial design, there remains the necessity to develop a better understanding of the evolving pathophysiology of this syndrome. Studies indicate that the development of marked immune suppression in sepsis is more often associated with morbid outcome. Dendritic cells, a critical immune cell type bridging the innate and adaptive immune response, not only are affected (killed) by the systemic inflammatory response but also contribute to (by impaired function) the development of immune suppression during sepsis. Here the authors attempt to review emerging data indicating the key role dendritic cells may play in sepsis-induced immune suppression. Undoubtedly, a better understanding of the dendritic cell's response during sepsis will be critical to developing novel strategies for fighting this deadly disease.

CD8+ T cells promote inflammation and apoptosis in the liver after sepsis: role of Fas-FasL

Although studies blocking the Fas pathway indicate it can decrease organ damage while improving septic (cecal ligation and puncture, CLP) mouse survival, little is known about how Fas-Fas ligand (FasL) interactions mediate this protection at the tissue level. Here, we report that although Fas expression on splenocytes and hepatocytes is up-regulated by CLP and is inhibited by in vivo short interfering RNA, FasL as well as the frequency of CD8(+) T cells are differentially altered by sepsis in the spleen (no change in FasL, decreased percentage of CD8(+) and CD4(+) T cells) versus the liver (increased FasL expression on CD8(+) T cells and increase in percentage/number). Adoptive transfer of CLP FasL(+/+) versus FasL(-/-) mouse liver CD8(+) T cells to severe combined immunodeficient or RAG1(-/-) recipient mice indicated that these cells could induce inflammation. The FasL-mediated cytotoxic capacity of these septic mouse liver CD8(+) T cells was shown by their ability to damage directly cultured hepatocytes. Finally, although CD8(-/-) mice exhibited a reduction in both CLP-induced liver active caspase-3 staining and blood interleukin-6 levels, only FasL(-/-) (but not CD8(-/-)) protected the septic mouse spleen from increasing apoptosis. Thus, although truncating Fas-FasL signaling ameliorates many untoward effects of sepsis, the pathological mode of action is distinct at the tissue level.

The contribution of CD4+ CD25+ T-regulatory-cells to immune suppression in sepsis

Studies have indicated that there is a development of generalized immune dysfunction after septic insult. However, the mechanisms responsible for these changes remain unclear. Recently, accumulating evidence shows that several lymphocyte subpopulations such as NKT-, CD4(+)-Th2-T-, CD8(+)-T-, gammadelta-T-, and CD4+ CD25+ T regulatory cells are capable of actively contributing to the induction of septic immune suppression. Thus, our aim was to investigate the contribution of CD4+ CD25+ cells to the immune dysfunction seen in sepsis. To study this, C57BL/6J, C57BL/6-Il6(tm1Kopf) (interleukin [IL] 6 -/-), and C57BL/6-Il10(tm1Cgn) (IL-10 -/-) mice were subjected to cecal ligation and puncture (CLP) or sham operations. Twenty-four hours later, blood was collected, and splenocytes were isolated. Phenotypic expression of CD4/CD25 (by fluorescence-activated cell sorter), cell proliferation (presented as proliferation index = [with anti-CD3]/[without anti-CD3]), and immune suppressive capacity (by in vitro add-back experiments) were assessed. The results indicate a marked elevation in CD4+ CD25+ cell levels and their proliferation index after sepsis in background mice. CD4+ CD25- cells from sham and CLP mice proliferated equally. However, coculture of CD4+ CD25- with CD4+ CD25+ cells suppressed their proliferation in both sham and CLP mice. Depletion of CD25+ cells in vivo before CLP markedly restored CD4+ CD25- proliferative capacity and Th1 cytokine release while not altering plasma proinflammatory cytokine levels. Subsequently, IL-6 -/- and IL-10 -/- mice were used to elucidate the possible mediator(s) regulating the changes seen after sepsis. Although CD4+ CD25+ cells increased after septic insult in both C57BL/6J and IL-6 -/- mice, this was not observed in IL-10 -/- mice. Similarly, in vitro proliferation studies showed that proliferation index increased in CD4+ CD25+ cells from septic C57BL/6J and IL6 -/- mice, but it remained the same in IL-10 -/- mice. Surprisingly, depletion of CD25+ cells before inducing sepsis did not alter septic mortality. Together, these findings suggest that although CD4+ CD25+ T regulatory cells induced by IL-10 seem to contribute to aspects of sepsis-induced lymphoid immune suppression, the oblation of CD25+ cells does not provide a survival advantage or disadvantage.

Fas-induced pulmonary apoptosis and inflammation during indirect acute lung injury

RATIONALE

Indirect acute lung injury (ALI) is associated with high morbidity and mortality. No specific therapies have been developed, because the underlying pathophysiological processes remain elusive.

OBJECTIVES

To investigate the contribution of Fas-induced apoptotic and nonapoptotic/inflammatory signaling to the pathology of indirect ALI.

METHODS

A mouse model of indirect ALI, induced by successive exposure to hemorrhagic shock and cecal ligation and puncture, was used. Quantification of active caspase-3 and the short splice variant of FLICE-inhibitory protein, (FLIP)short, was performed by Western blotting and immunohistochemistry, and cytokines/chemokines were assessed by cytometric bead array or ELISA. M30 immunostaining was done to evaluate epithelial cell apoptosis. Lung injury was assessed on the basis of myeloperoxidase activity, bronchoalveolar lavage protein, and lung histology.

MEASUREMENTS AND MAIN RESULTS

Twelve hours after insult, lung monocyte chemoattractant protein-1, keratinocyte-derived chemokine, macrophage inflammatory protein-2, IL-6, tumor necrosis factor-alpha, and caspase-3 were increased and FLIP(short) was decreased. Fas- and Fas ligand-deficient mice showed marked protection from lung inflammation and apoptosis and decreased ALI. This was associated with a 10-day survival benefit. Similarly, 4 hours after pulmonary instillation of Fas-activating antibody in vivo, lung chemokines were markedly elevated in background mice and, interestingly, to a similar degree in macrophage-deficient animals. Fas activation on lung epithelial cells in vitro led to chemokine production that was dependent on extracellular signal-regulated kinase.

CONCLUSIONS

Activation of apoptotic and nonapoptotic/inflammatory Fas signaling is an early important pathophysiological event in the development of indirect ALI after hemorrhagic shock and sepsis, in which lung epithelial cells appear to play a central role.

MyD88-dependent expansion of an immature GR-1(+)CD11b(+) population induces T cell suppression and Th2 polarization in sepsis

Polymicrobial sepsis alters the adaptive immune response and induces T cell suppression and Th2 immune polarization. We identify a GR-1⁺CD11b⁺ population whose numbers dramatically increase and remain elevated in the spleen, lymph nodes, and bone marrow during polymicrobial sepsis. Phenotypically, these cells are heterogeneous, immature, predominantly myeloid progenitors that express interleukin 10 and several other cytokines and chemokines. Splenic GR-1⁺ cells effectively suppress antigen-specific CD8⁺ T cell interferon (IFN) γ production but only modestly suppress antigen-specific and nonspecific CD4⁺ T cell proliferation. GR-1⁺ cell depletion in vivo prevents both the sepsis-induced augmentation of Th2 cell–dependent and depression of Th1 cell–dependent antibody production. Signaling through MyD88, but not Toll-like receptor 4, TIR domain–containing adaptor-inducing IFN-β, or the IFN-α/β receptor, is required for complete GR-1⁺CD11b⁺ expansion. GR-1⁺CD11b⁺ cells contribute to sepsis-induced T cell suppression and preferential Th2 polarization.

Regulation of adipocyte differentiation by PEGylated all-trans retinoic acid: reduced cytotoxicity and attenuated lipid accumulation

Obesity is major risk factor for many disorders, including diabetes, hypertension and heart disease. Unfortunately, there is a dearth of therapeutic agents available to clinicians for the treatment of obesity. The principal aim of this study was to investigate whether PEGylated all-trans retinoic acid (PRA) can have favorable stability and biological activity in 3T3-L1 preadipocytes as an antiobesity drug. Here, we found that PRA inhibits the process of adipogenesis, including survival of adipocytes and differentiation to mature adipocytes. The results showed that RA nanoparticles (NPs) were prepared by PEGylation; below 200 nm, PRA-NPs were obtained. Moreover, PRA decreased glycerol-3-phosphate dehydrogenase activity in 3T3-L1 preadipocytes by acting with major adipocyte marker proteins such as PPARgamma2, C/EBPalpha and aP2 modulators. Apoptosis, in addition, increased as the level of RA increased from 10 to 20 microM, whereas PRA reduced apoptosis with increasing concentrations. Our data suggest that PRA-NP has potential as an antiobesity drug carrier due to its small particle size and PEGylated core-shell structure. In addition, our results suggest that PRA inhibits the process of adipogenesis and may be developed to treat obesity. Based on these results, PRA is suitable for adipocyte studies, and an enhanced effect of PRA with adipocyte differentiation offers a challenging approach for pharmaceutical applications.

Beneficial Versus Detrimental Effects of Neutrophils Are Determined by the Nature of the Insult

BACKGROUND

Neutrophils are thought to play pivotal roles in eliminating pathogens, and they have also been implicated in end organ dysfunction associated with systemic inflammatory response syndrome (SIRS). Because modulating neutrophil survival and function has been proposed as a therapy for sepsis, it remains critical to determine under which circumstances modulating neutrophil function is efficacious. The aim of this study was to investigate whether sustaining the presence of neutrophils activated by hemorrhagic shock (HEM) would be disadvantageous during subsequent sepsis, ie, inflammation plus infection, or systemic inflammation without infection.

STUDY DESIGN

Transgenic mice, overexpressing the antiapoptotic protein Bcl-2 in a myeloid restricted fashion (Bcl-2(my)), and controls (C57) were subjected to HEM, followed 24 hours thereafter either by cecal ligation and puncture to induce sepsis, or by intraperitoneal injection of lipopolysaccharide to induce SIRS. Lung injury was assessed by bronchoalveolar lavage fluid protein and histology. Lung, plasma, and liver cytokines were quantified through CBA or ELISA.

RESULTS

In sepsis, Bcl-2(my) had increased lung neutrophil and lower lung bacteria counts compared with C57. This translated into a marked early survival benefit for Bcl-2(my). There were no differences between Bcl-2(my) and C57 with respect to the degree of lung injury or lung and plasma cytokines. In contrast, in SIRS, Bcl-2(my) exhibited markedly increased acute lung injury and lung and plasma cytokines when compared with C57. Bcl-2(my) also had a profound survival disadvantage.

CONCLUSIONS

Whether effects of prolonged survival of hemorrhage-primed neutrophils are beneficial or detrimental is determined by the nature of the second insult. During sepsis, prolonging neutrophil survival is beneficial, enhancing antimicrobial activity. Alternatively, during inflammation without infection, increased organ damage by long-lived neutrophils is detrimental.

The apoptotic pathway as a therapeutic target in sepsis

Recent research has yielded many interesting and potentially important therapeutic targets in sepsis. Specifically, the effects of antagonistic anti-cytokine therapies (tumor necrosis factor-alpha [TNF-alpha], interleukin-1 [IL-1]) and anti-endotoxin strategies utilizing antibodies against endotoxin or endotoxin receptor/carrier molecules (anti-CD14 or anti-LPS-binding protein) have been studied. Unfortunately, these approaches often failed clinically, and in many cases, the efficacy of these treatments was dependent on the severity of sepsis. Recently, clinical trials using insulin to lock blood glucose levels and activated protein C treatment have showed that while they provided some survival benefit, their efficacy does not appear to be predicated solely upon anti-inflammatory effects. Here, we will review work done in animal models of polymicrobial sepsis and clinical findings that support the hypothesis that apoptosis in the immune system is a pathologic event in sepsis that can be a therapeutic target. In this respect, experimental studies looking at the septic animal suggest that loss of lymphocytes during sepsis may be due to dysregulated apoptosis and that this appears to be brought on by a variety of mediators effecting 'intrinsic' as well as 'extrinsic' cell death pathways. From a therapeutic perspective this has provided a number of novel targets for clinically successful current, as well as future therapies, such as caspases (caspase inhibition/protease inhibition), pro-apoptotic protein-expression (via administration and/or over-expression of Bcl-2) and the death receptor family Fas-FasL (via. FasFP [fas fusion protein] and the application of siRNA against a number pro-apoptotic factors).

Shock and hemorrhage: an overview of animal models

Shock resulting from life-threatening blood loss (hemorrhage) remains a common complication of traumatic injury. Intensive experimental efforts are needed if we are to understand the pathological effect(s) of hemorrhagic shock, alone or in association with traumatic tissue injury, and to reverse this deleterious process in trauma patients. Here, we overview selected studies that are representative of the different hemorrhagic shock models, considering their advantages and disadvantages from a scientific and clinical perspective. Fixed-pressure versus fixed-volume versus uncontrolled hemorrhage models, with or without tissue injury, will be discussed, as well as small versus large animal models. Most of these models are nonlethal in nature, and allow the researcher to understand the changes that contribute to increased susceptibility to subsequent infection or the development of multiple organ failure. We also consider some of the confounders in these models, including anesthesia, the nature of resuscitation, and the use of anticoagulants. The selection of model must take into consideration not only the need for experimental control but must also adequately reflect the clinical pathobiology of shock if we are to develop better pharmacological interventions.

Down-regulation of PPARgamma2-induced adipogenesis by PEGylated conjugated linoleic acid as the pro-drug: Attenuation of lipid accumulation and reduction of apoptosis

This study is designed to evaluate whether the PEGylated conjugated linoleic acid (PCLA) as the pro-drug can have favorable stability, bioavailability, and anti-adipogenic activity in 3T3-L1 cells for anti-obesity when compared with conjugated linoleic acid (CLA) itself. The CLA was simply coupled to poly(ethylene glycol) (PEG) at the melting state without solvents or catalysts through ester linkages between the carboxylic group of CLA and the hydroxyl group of PEG. To confirm of PCLA as the pro-drug, CLA release from PCLA was investigated by using high-performance liquid chromatographic (HPLC), showing that CLA release from PCLA was almost 90% in a nearly continuous fashion over the next 75h. Apoptosis was promoted by both CLA- and PCLA-treatments with increasing concentrations. However, the level of cell apoptosis induced by PCLA was lower than that induced by CLA owing to the biocompatible and hydrophilic properties of PEG. Moreover, the PCLA decreased glycerol-3-phosphate dehydrogenase (GPDH) activity in 3T3-L1 cells by acting upon major adipocyte marker proteins such as PPARgamma2, C/EBPalpha, and aP2 modulators. Furthermore, either CLA or PCLA stimulated basal, but not isoproterenol-sensitive, lipolysis in our cell model, suggesting that both CLA and PCLA may stimulate lipolysis via hormone sensitive lipase (HSL)-independent mechanisms. These results suggest that the PCLA may prove to be a stable pro-drug to control the deposition of fat in the human body, and that the anti-adipogenic effect of the PCLA on 3T3-L1 cells will offer a challenging approach for anti-obesity.

Divergent roles of murine neutrophil chemokines in hemorrhage induced priming for acute lung injury

Neutrophil associated lung injury is identified with a variety of local and systemic priming insults. In vitro studies have shown that TNF-alpha mediated suppression of neutrophil apoptosis is due to the secretion of interleukin-8 (IL-8), a human chemokine shown to alter neutrophil chemotaxis. Our initial in vitro antibody neutralization studies with neutrophil chemotactic proteins, keratinocyte-derived chemokine (KC) and macrophage inflammatory protein-2alpha (MIP-2alpha), mouse IL-8 homologues, indicate that MIP-2alpha but not KC appears to mediate TNF-alpha suppression of mouse neutrophil apoptosis. Therefore, we hypothesized that in vivo neutralization of KC or MIP-2alpha during an initial priming insult would produce differential effects on the extent of lung injury by restoring normal neutrophil apoptotic function. To assess this, mice were hemorrhaged followed with septic challenge at 24 h. Antibody against KC or MIP-2alpha or a nonspecific IgG was given during resuscitation immediately following hemorrhage. Anti-MIP-2alpha treatment resulted in a significant reduction in lung tissue IL-6 and myeloperoxidase levels. Percentage of neutrophil apoptosis increased significantly in the anti-KC group. Tissue and plasma KC and MIP-2alpha were reduced in their respective treatment groups. These data suggest that KC and MIP-2alpha differ in their mediation of neutrophil function (apoptosis and chemotaxis) and contribution to the pathogenesis of lung injury following hemorrhage subsequent to sepsis.

A. Deficiency of gammadelta T lymphocytes contributes to mortality and immunosuppression in sepsis

Studies have indicated that gammadelta T lymphocytes play an important role in the regulation of immune function and the clearance of intracellular pathogens. We have recently reported that intraepithelial lymphocytes (IEL), which are rich in gammadelta T cells, within the small intestine illustrated a significant increase in apoptosis and immune dysfunction in mice subjected to sepsis. However, the contribution of gammadelta T cells to the host response to polymicrobial sepsis remains unclear. In this study, we initially observed that after sepsis induced by cecal ligation and puncture (CLP), there was an increase in small intestinal IEL CD8+gammadelta+ T cells in control gammadelta+/+ mice. Importantly, we subsequently found an increased early mortality in mice lacking gammadelta T cells (gammadelta-/- mice) after sepsis. This was associated with decreases in plasma TNF-alpha, IL-6, and IL-12 levels in gammadelta-/- mice compared with gammadelta+/+ mice after sepsis. In addition, even though in vitro LPS-stimulated peritoneal macrophages showed a reduction in IL-6 and IL-12 release after CLP, these cytokines were less suppressed in macrophages isolated from gammadelta-/- mice. Alternatively, IL-10 release was not different between septic gammadelta+/+ and gammadelta-/- mice. Whereas T helper (Th)1 cytokine release by anti-CD3-stimulated splenocytes was significantly depressed in septic gammadelta+/+ mice, there was no such depression in gammadelta-/- mice. However, gammadelta T cell deficiency had no effect on Th2 cytokine release. These findings suggest that gammadelta T cells may play a critical role in regulating the host immune response and survival to sepsis, in part by alteration of the level of IEL CD8+gammadelta+ T cells and through the development of the Th1 response.

Deafferentation-disconnection neglect induced by posterior cerebral artery infarction

OBJECTIVE

To investigate patients with posterior cerebral artery (PCA) infarctions to learn whether hemispatial neglect is more frequent and severe after right than left PCA infarction; whether visual field defects (VFDs) influence the presence or severity of hemispatial neglect; and the anatomic loci of lesions that are associated with hemispatial neglect.

METHODS

The authors recruited 45 patients with PCA infarction that involved only the occipital lobe or the occipital lobe plus other areas served by the PCA. All subjects received seven neglect tests within 2 months after onset.

RESULTS

Overall, the frequency of hemispatial neglect was 42.2%. The frequency did not significantly differ between the right (48.0%) and left (35.0%) PCA groups, but the severity of hemispatial neglect was significantly greater in the right group. VFD alone did not influence the frequency or severity of neglect after controlling other variables. Isolated occipital lesions were rarely associated with hemispatial neglect, and it was only the occipital plus splenial lesion that significantly influenced the frequency and severity of neglect.

CONCLUSIONS

This study suggests that after excluding such confounding factors as aphasia or hemiplegia, neglect frequency does not differ between the right and left posterior cerebral artery (PCA) groups, but the severity of neglect is greater after right PCA infarctions; even in the acute stage of PCA infarction; visual field defect from an isolated occipital lesion does not cause hemispatial neglect; and the injury to both the occipital lobe and the splenium of the corpus callosum is important for producing hemispatial neglect with PCA infarction.

The role and regulation of apoptosis in sepsis

Today, sepsis continues to be a growing problem in the critically ill patient population. A number of laboratories have been interested in understanding how changes in immune cell apoptosis during sepsis appear to contribute to septic morbidity. Consistently, it has been found that immune cell apoptosis is altered in a variety of tissue sites and cell populations both in experimental animals and humans. While divergent mediators, such as steroids and TNF, contribute to some of these apoptotic changes, their effects are tissue and cell population selective. Inhibition of FasL-Fas signaling (by either FasL gene deficiency, in vivo gene silencing [siRNA] or with FasL binding protein) protects septic mice from the onset of marked apoptosis and the morbidity/mortality seen in sepsis. Further, this extrinsic apoptosis response appears to utilize aspects of the Bid-induced mitochondrial pathway. This is in keeping with the findings that pan-specific caspase inhibition or the overexpression of Bcl-2 also protect these animals from the sequellae of sepsis.

Contribution of anti-inflammatory/immune suppressive processes to the pathology of sepsis

Sepsis is the leading cause of death in critically ill patients in the United States. It is associated with enormous expenditures within the health care system and despite substantial human, medical and fiscal resources directed at this clinical entity we have only had a modest effect on the septic patient's long-term survival. However, extensive studies over the last few decades have begun to reveal important pathophysiological processes around which a few promising therapeutic strategies with potential benefits may be derived. It is generally believed, that the body reacts to a septic challenge with an intense hyper-inflammatory response, designed to eliminate the underlying pathogen. However, along with and in response to the intense pro-inflammatory reaction, mechanisms fall into place to counter regulate (control) this initial response, typically resulting in a down regulation of the inflammatory response. This frequently results in dysfunction of various immunological conditions and may result in the inability to ward off the infection and consecutively lead to multiple organ dysfunction, multiple organ failure and death. It is the aberrant development of this anti-inflammatory/ immunosuppressive response, in which it is important to expand our understanding of pathological components to develop potential remedy. Upon this background this review aims to provide an overview on the pathophysiological mechanisms which initiate or maintain the down regulation of the immune response to a septic challenge and which might be a starting point for the development of therapeutic strategies.

Role of alveolar macrophage and migrating neutrophils in hemorrhage-induced priming for ALI subsequent to septic challenge

Acute lung injury (ALI) is identified with the targeting/sequestration of polymorphonuclear leukocytes (PMN) to the lung. Instrumental to PMN targeting are chemokines [e.g., macrophage inflammatory protein-2 (MIP-2), keratinocyte-derived chemokine (KC), etc.] produced by macrophage, PMN, and other resident pulmonary cells. However, the relative contribution of resident pulmonary macrophages as opposed to PMN in inducing ALI is poorly understood. We therefore hypothesize that depletion of peripheral blood PMN and/or the oblation of a macrophage-mediated PMN chemokine signal (via macrophage deficiency) will reduce the inflammation and ALI observed in mice following hemorrhage (Hem) and subsequent sepsis (CLP) in our murine model of ALI. To examine this we pretreated mice with either 500 μg anti-mouse Gr1 antibody/animal (to deplete PMN) or subjected mice deficient in mature macrophage (B6C3Fe-a/a-CsF1op) to Hem (90 min at 35 ± 5 mmHg) followed by resuscitation. Twenty-four hours post-Hem, mice were subjected to CLP and killed 24 h later, and lung tissue samples were collected. Our data showed that in the absence of either peripheral blood PMN or mature tissue macrophages there was a suppression of IL-6, KC, and MIP-2 levels in lung tissue from Hem/CLP mice as well as a reduction in PMN influx to the lung and lung injury (bronchoalveolar lavage fluid protein). In contrast, lung tissue IL-10 and TNF-α levels were suppressed in the macrophage-deficient Hem/CLP mice compared with PMN-depleted Hem/CLP mice. Together, these data suggest that both the PMN and the macrophage are required to induce inflammation seen here, however, macrophage not PMN regulate the release of IL-10, independent of local changes in TNF.

Silencing of Fas, but not caspase-8, in lung epithelial cells ameliorates pulmonary apoptosis, inflammation, and neutrophil influx after hemorrhagic shock and sepsis

Apoptosis and inflammation play an important role in the pathogenesis of direct/pulmonary acute lung injury (ALI). However, the role of the Fas receptor-driven apoptotic pathway in indirect/nonpulmonary ALI is virtually unstudied. We hypothesized that if Fas or caspase-8 plays a role in the induction of indirect ALI, their local silencing using small interfering RNA (siRNA) should be protective in hemorrhage-induced septic ALI. Initially, as a proof of principle, green fluorescent protein-siRNA was administered intratracheally into transgenic mice overexpressing green fluorescent protein. Twenty-four hours after siRNA delivery, lung sections revealed a significant decrease in green fluorescence. Intratracheally administered Cy-5-labeled Fas-siRNA localized primarily in pulmonary epithelial cells. Intratracheal instillation of siRNA did not induce lung inflammation via toll-like receptor or protein kinase PKR pathways as assessed by lung tissue interferon-alpha, tumor necrosis factor-alpha, and interleukin (IL)-6 levels. Mice subjected to hemorrhagic shock and sepsis received either Fas-, caspase-8-, or control-siRNA intratracheally 4 hours after hemorrhage. Fas- or caspase-8-siRNA significantly reduced lung tissue Fas or caspase-8 mRNA, respectively. Only Fas-siRNA markedly diminished lung tissue tumor necrosis factor-alpha, IL-6, IL-10, interferon-gamma, IL-12, and caspase-3 activity. Fas-siRNA also preserved alveolar architecture and reduced lung neutrophil infiltration and pulmonary epithelial apoptosis. These data indicate the pathophysiological significance of Fas activation in nonpulmonary/shock-induced ALI and the feasibility of intrapulmonary administration of anti-apoptotic siRNA in vivo.

In vivo delivery of caspase-8 or Fas siRNA improves the survival of septic mice

Although studies have shown increased evidence of death receptor-driven apoptosis in intestinal lymphoid cells, splenocytes, and the liver following the onset of polymicrobial sepsis, little is known about the mediators controlling this process or their pathologic contribution. We therefore attempted to test the hypothesis that the hydrodynamic administration of small interfering RNA (siRNA) against the death receptor, Fas or caspase-8, should attenuate the onset of morbidity and mortality seen in sepsis, as produced by cecal ligation and puncture (CLP). We initially show that in vivo administration of green fluorescent protein (GFP) siRNA in GFP transgenic mice results in a decrease in GFP fluorescence in most tissues. Subsequently, we also found that treating septic nontransgenic mice with siRNA targeting Fas or caspase-8 but not GFP (used as a control here) decreased the mRNA, in a sustained fashion up to 10 days, and protein expression of Fas and caspase-8, respectively. In addition, transferase-mediated dUTP (deoxyuridine triphosphate) nick end labeling (TUNEL) and active caspase-3 analyses revealed a decrease in apoptosis in the liver and spleen but not the thymus following siRNA treatment. Indices of liver damage were also decreased. Finally, the injection of Fas or caspase-8 given not only 30 minutes but up to 12 hours after CLP significantly improved the survival of septic mice.

Loss of signal transducer and activator of transduction 4 or 6 signaling contributes to immune cell morbidity and mortality in sepsis

OBJECTIVE

The role of signal transducer and activator of transduction (STAT) 4 vs. 6 has been assessed thus far only in a model of high mortality strongly driven by proinflammation alone. Their role in a low-mortality (LD25) model of sepsis remains unclear.

DESIGN AND SETTING

Prospective controlled animal study in a research laboratory.

SUBJECTS

STAT4 and STAT6 knockout mice.

INTERVENTIONS

We induced sepsis by cecal ligation and puncture (CLP) or sham CLP in three groups of mice: (a) STAT4-/-, (b) STAT6-/-, (c) BALB/c. Splenic T cells or macrophages were then harvested 24 h after CLP, and their ability to produce cytokines was assessed.

RESULTS

Following CLP T-cells from BALB/c mice were suppressed in the ability to release the Th1 cytokines interleukin (IL) 2 and interferon gamma. The release of Th2 cytokine IL-10 was increased. The Th1 response of STAT4-deficient animals was not only markedly lower in shams but was further suppressed by CLP. The Th2 cytokine response was elevated even more than that of the septic BALB/c. This was associated with lower survival than in the BALB/c. STAT6 deficiency resulted in a stronger Th1 response and a suppressed Th2 response to CLP. A similar difference between IL-12 and IL-10 release was seen in macrophages from these mice. Interestingly, while this resulted in improved survival, compared to STAT4-/- mice, the STAT6-/- animals still had a higher mortality than the BALB/c.

CONCLUSIONS

These data suggest that contributions from both STAT4 driven processes as well as STAT6 responses are needed in a balanced fashion to maximize the animals' ability to survive septic challenge.

Leukocyte apoptosis and its significance in sepsis and shock

Sepsis and multiple organ failure continue to be significant problems among trauma, burn, and the critically ill patient population. Thus, a number of laboratories have focused on understanding the role of altered apoptotic cell death in contributing to immune and organ dysfunction seen in sepsis and shock. Immune cells that undergo altered apoptotic changes include neutrophils, macrophages, dendritic cells, as well as various lymphocyte populations. Evidence of epithelial as well as endothelial cell apoptotic changes has also been reported. Although mediators such as steroids, tumor necrosis factor, nitric oxide, C5a, and Fas ligand (FasL) appear to contribute to the apoptotic changes, their effects are tissue- and cell population-selective. As inhibiting Fas-FasL signaling (e.g., gene deficiency, Fas fusion protein, or Fas short interfering RNA administration), caspase inhibition (caspase mimetic peptides), and/or the overexpression of downstream antiapoptotic molecules (e.g., Bcl-2, Akt) improve survival of septic mice, it not only demonstrates the pathological significance of this process but points to novel targets for the treatment of sepsis.

In vivo gene silencing (with siRNA) of pulmonary expression of MIP-2 versus KC results in divergent effects on hemorrhage-induced, neutrophil-mediated septic acute lung injury

Lung injury in trauma patients exposed to a secondary infectious/septic challenge contributes to the high morbidity/mortality observed in this population. Associated pathology involves a dys-regulation of immune function, specifically, sequestration of activated polymorphonuclear neutrophils (PMN) in the lungs. The targeting of PMN is thought to involve the release of chemokines from cells within the local environment, creating a concentration gradient along which PMN migrate to the focus of inflammation. Keratinocyte-derived chemokine (KC) and macrophage-inflammatory protein-2 (MIP-2) are murine neutrophil chemokines identified as playing significant but potentially divergent roles in the pathogenesis of acute lung injury (ALI). In the current study, we examined the contribution of local pulmonary cells to the production of KC and MIP-2 and the pathogenesis of ALI. We hypothesized that local silencing of KC or MIP-2, via the local administration of small interference RNA (siRNA) against KC or MIP-2, following traumatic shock/hemorrhage (Hem), would suppress signaling for PMN influx to the lung, thereby reducing ALI associated with a secondary septic challenge (cecal ligation and puncture). Assessment of siRNA local gene silencing was done in green fluorescent protein (GFP)-transgenic, overexpressing mice. A marked suppression of GFP expression was observed in the lung 24 h following intratracheal (i.t.) instillation of GFP siRNA, which was not observed in the liver. To test our hypothesis, siRNA against KC or MIP-2 (75 ug/C3H/Hen mouse) was instilled (i.t.) 2 h post-Hem (35 mm Hg for 90 min, 4x LRS Rx.). Twenty-four hours after, mice were subjected to septic challenge and then killed 24 h later. i.t. MIP-2 siRNA significantly (P < 0.05, ANOVA-Tukey's test, n = 5-6/group) reduced tissue and plasma interleukin (IL)-6, tissue MIP-2 (enzyme-linked immunosorbent assay), as well as neutrophil influx [myeloperoxidase (MPO) activity]. In contrast, KC siRNA treatment reduced plasma KC, tissue KC, and IL-6 but produced no significant reduction in plasma IL-6 or MPO. Neither treatment reduced tissue or plasma levels of tumor necrosis factor alpha compared with vehicle. These data support not only our hypothesis that local pulmonary chemokine production of MIP-2, to a greater extent than KC, contributes to the pathogenesis of PMN-associated ALI following Hem but also the use of siRNA as a potential therapeutic.

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.

Complete Nonvisualization of Basilar Artery on MR Angiography in Patients with Vertebrobasilar Ischemic Stroke: Favorable Outcome Factors

BACKGROUND

In vertebrobasilar ischemic stroke, magnetic resonance angiography (MRA) occasionally fails to visualize the basilar artery, but in these patients, little attention has been given to establishing correlations between the clinical and the radiological findings. Our aim was to identify clinical or radiological measures that could assist in predicting a favorable clinical outcome.

METHODS

Risk factors, clinicoradiological features, and functional outcomes were assessed in 40 patients with vertebrobasilar ischemic stroke whose basilar arteries were absent on MRA. The presence of potential feeding arteries to the posterior circulation was recorded from a review of the MRA data. To permit quantitative analysis of the images, a potential feeding artery score (PFAS; range: 0-8) was established. One point was assigned when a signal was seen from an intracranial vertebral artery, a posterior inferior cerebellar artery, a superior cerebellar artery, or a posterior cerebral artery. On MRI, the location of the infarction was classified as involving the proximal, middle, and distal territories of the intracranial posterior circulation. The infarctions were also categorized as single- or multi-sector infarctions, and according to whether more than one penetrating or branch artery was involved. Clinical outcomes were classified as favorable (modified Rankin Scale = 0-2) or poor (modified Rankin Scale = 3-6).

RESULTS

The clinical outcome was favorable in 30% (n = 12) of patients, and poor in 70% (n = 28). A transient ischemic attack preceded the stroke in 48% of patients, especially those with a favorable outcome (67%). Patients with a favorable outcome had a higher PFAS (p = 0.036) and an increased incidence of single-sector infarction (p = 0.049).

CONCLUSIONS

Our study suggests that a higher PFAS, accompanied by a single-sector infarction, is a predictor of improved clinical outcome in patients with vertebrobasilar ischemic stroke in which the basilar artery was absent on MRA.

CXCR2 inhibition suppresses hemorrhage-induced priming for acute lung injury in mice

Polymorphonuclear neutrophil (PMN) extravasation/sequestration in the lung and a dysregulated inflammatory response characterize the pathogenesis of acute lung injury (ALI). Previously, we have shown that hemorrhage (Hem) serves to prime PMN such that subsequent septic challenge [cecal ligation and puncture (CLP)] produces a pathological, inflammatory response and consequent lung injury in mice. Keratinocyte-derived chemokine (KC) and macrophage inflammatory protein-2 (MIP-2) are murine CXC chemokines found elevated in the lungs and plasma following Hem/CLP and have been reported by others to share a common receptor (CXCR2). Based on these data, we hypothesize that blockade of CXCR2 immediately following Hem would suppress KC and MIP-2 priming of PMN, thereby reducing the inflammatory injury observed following CLP. To assess this, Hem mice (90 min at 35+/-5 mmHg) were randomized to receive 0, 0.4, or 1 mg antileukinate (a hexapeptide inhibitor of CXCRs) in 100 microl phosphate-bufferd saline (PBS)/mouse subcutaneously, immediately following resuscitation (Ringer's lactate-4x drawn blood volume). Twenty-four hours post-Hem, mice were subjected to CLP and killed 24 h later. The results show that blockade of CXCR2 significantly (P<0.05, Tukey's test) reduced PMN influx, lung protein leak, and lung-tissue content of interleukin (IL)-6, KC, and MIP-2 and increased tissue IL-10 levels. Plasma IL-6 was significantly decreased, and IL-10 levels increased in a dose-dependent manner compared with PBS-treated mice. A differential effect was observed in plasma levels of KC and MIP-2. KC showed a significant reduction at the 0.4 mg antileukinate dose. In contrast, plasma MIP-2 was significantly elevated at both doses compared with the PBS-treated controls. Together, these data demonstrate that blockade of CXCR2 signaling attenuates shock-induced priming and ALI observed following Hem and subsequent septic challenge in mice.

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.

Plutonium isotopes in seas around the Korean Peninsula

239+240Pu concentrations and 240Pu/239Pu atom ratios in coastal seas adjacent to the Korean Peninsula were determined, during the period 1999 to 2002, to assess the current distribution and to identify sources of Pu isotopes. 239+240Pu concentrations in surface waters ranged from 3.1 to 22.3 mBq m(-3) with higher concentrations in winter than in summer. 239+240Pu concentrations in seawaters around the Korean Peninsula are greater than that in the western North Pacific. 240Pu/239Pu atom ratios ranged from 0.18 to 0.33 with an average value of 0.25+/-0.03, which is significantly higher than the global fallout average. The 240Pu/239Pu atom ratios of the 2000 m deep entire water column in the south western part of the East Sea (Sea of Japan) was comparable to that observed in waters near Bikini Atoll. The higher 240Pu/239Pu atom ratios than that of global fallout may be explained by the hypothesis that the earlier input signal of low 240Pu/239Pu atom ratio (0.18-0.19) of global fallout plutonium in seas adjacent to the Korean Peninsula is being gradually diluted by the high 240Pu/239Pu atom ratio plutonium transported from the tropical Pacific Proving Grounds via prevailing ocean current.

10-Year Outcome for Men With Localized Prostate Cancer Treated With External Radiation Therapy:: Results of a Cohort Study

PURPOSE

We determine the efficacy of conventional dose, external beam radiation for localized prostate cancer using cohort analysis with maximized followup.

MATERIALS AND METHODS

A total of 205 men with T1-2 prostate cancer were treated with conventional external beam radiation to a median and modal dose of 68.4 Gy during a 16-month period from 1991 to 1993. Followup was maximized in these patients, and median followup for those alive with or without disease was 114 months.

RESULTS

Median patient age at treatment was 72 years, and overall survival at 5 and 10 years was 78% and 53%, respectively. The actuarial risk of local failure was 18% at 10 years as was the risk of metastatic disease. The actuarial risk of being free of biochemical failure at 10 years (American Society for Therapeutic Radiology and Oncology definition) was 49%. That risk was 42% if the definition was used without backdating failure to a time between last low value and first increase. When a crude analysis of 10-year outcome was performed 127 of the 205 treated patients (62%) were still alive, including 59% with no evidence of biochemical failure and a median prostate specific antigen of 1.0 ng/ml. Of the 78 men (38% of total) who died during the 10 years 32 died either of or with recurrent cancer.

CONCLUSIONS

Mature followup minimizes many of the biases seen in previously published radiation series. This study provides a yardstick against which newer radiation modalities may be measured.

Sepsis-induced changes in macrophage co-stimulatory molecule expression: CD86 as a regulator of anti-inflammatory IL-10 response

BACKGROUND

Sepsis remains a substantial risk after surgery or other trauma. Macrophage dysfunction, as a component of immune suppression seen during trauma and sepsis, appears to be one of the contributing factors to morbidity and mortality. However, whereas it is known that the ability of macrophages to present antigen and express major histocompatibility complex MHC class II molecules is decreased during sepsis, it is not known to what extent this is associated with the loss of co-stimulatory receptor expression. Our objectives in this study were, therefore, to determine if the expression of co-stimulatory molecules, such as CD40, CD80, or CD86, on peritoneal/splenic/liver macrophages were altered by sepsis (cecal ligation [CL] and puncture [CLP] or necrotic tissue injury (CL) alone; and to establish the contribution of such changes to the response to septic challenge using mice that are deficient in these receptors.

METHODS

To address our first objective, male C3H/HeN mice were subjected to CLP, CL, or sham (n = four to six mice/group), and the adherent macrophages were isolated from the peritoneum, spleen, or liver at 24 h post-insult. The macrophages were then analyzed by flow cytometry for their ex vivo expression of CD40, CD80, CD86, and/or MHC II.

RESULTS

The expression of CD86 and MHC II, but not CD40 or CD80, were significantly decreased on peritoneal macrophages after the onset of sepsis or CL alone. In addition, CD40 expression was significantly increased in Kupffer cells after sepsis. Alternatively, splenic macrophages from septic or CL mice did not show changes in the expression of CD80, CD86, or CD40. To the degree that the loss of CD86 expression might contribute to the changes reported in macrophage function in septic mice, we subsequently examined the effects of CLP on CD86 -/- mice. Interestingly, we found that, unlike the background controls, neither the serum IL-10 concentrations nor the IL-10 release capacity of peritoneal macrophages from septic CD86 -/- mice were increased.

CONCLUSION

Together, these data suggest a potential role for the co-stimulatory receptor CD86/B7-2 beyond that of simply promoting competent antigen presentation to T-cells, but also as a regulator of the anti-inflammatory IL-10 response. Such a role may implicate the latter response in the development of sepsis-induced immune dysfunction.

Sepsis-induced SOCS-3 expression is immunologically restricted to phagocytes

We have shown that immune cells from septic mice exhibit a suppressed response to exogenous stimuli in vitro. The suppressors of the cytokine signaling (SOCS) family are proteins that block intracellular signaling and can be induced by inflammatory mediators. Therefore, we hypothesized that SOCS-3 is up-regulated in immune cells in response to a septic challenge induced by cecal ligation and puncture (CLP). Mice were subjected to CLP or sham-CLP, and 2-48 h later, the blood, thymus, spleen, lung, and peritoneal leukocytes were harvested and examined. SOCS-3 was undetectable in thymocytes or blood leukocytes. In contrast, SOCS-3 was up-regulated in the spleen, lung, and peritoneal leukocytes in a time-dependent manner. Further examination revealed that only the macrophages and neutrophils expressed SOCS-3. These data suggest that cytokines and bacterial toxins present during sepsis have the ability to suppress the cytokine and/or lipopolysaccharide response and the function of immune cells by up-regulating SOCS-3.

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.

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.

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.

Hyperventilation-induced limb shaking TIA in Moyamoya disease

The authors present a case of hyperventilation-induced left upper limb shaking from an underlying Moyamoya disease. Video EEG monitoring and SPECT study were performed. Leptomeningeal collateral circulation was investigated by conventional angiography and by SPECT study with acetazolamide. Limb shaking in Moyamoya disease may result from a transient hypoperfusion of the contralateral frontoparietal cortex rather than basal ganglia.