The beta-glucan receptor,dectin-1, is predominantly expressed on the surface of cells of the monocyte/macrophage and neutrophil lineages

We recently identified dectin-1 (betaGR) as a major beta-glucan receptor on leukocytes and demonstrated that it played a significant role in the non-opsonic recognition of soluble and particulate beta-glucans. Using a novel mAb (2A11) raised against betaGR, we show here that the receptor is not dendritic cell-restricted as first reported, but is broadly expressed, with highest surface expression on populations of myeloid cells (monocyte/macrophage (Mphi) and neutrophil lineages). Dendritic cells and a subpopulation of T cells also expressed the betaGR, but at lower levels. Alveolar Mphi, like inflammatory Mphi, exhibited the highest surface expression of betaGR, indicative of a role for this receptor in immune surveillance. In contrast, resident peritoneal Mphi expressed much lower levels of betaGR on the cell surface. Characterization of the nonopsonic recognition of zymosan by resident peritoneal Mphi suggested the existence of an additional beta-glucan-independent mechanism of zymosan binding that was not observed on elicited or bone marrow-derived Mphi. Although this recognition could be inhibited by mannan, we were able to exclude involvement of the Mphi mannose receptor and complement receptor 3 in this process. These observations imply the existence of an additional mannan-dependent receptor involved in the recognition of zymosan by resident peritoneal Mphi.     

Role of polymorphonuclear neutrophils on infectious complications stemming from Enterococcus faecalis oral infection in thermally injured mice

Thermally injured mice are susceptible to Enterococcus faecalis translocation. In this study, the role of polymorphonuclear neutrophils (PMN) on the development of sepsis stemming from E. faecalis translocation was studied in SCID-beige (SCIDbg) mice depleted of PMN (SCIDbgN mice) or macrophages (Mphi) and PMN (SCIDbgMN mice). Sepsis was not developed in SCIDbgN mice orally infected with E. faecalis, while the orally infected pathogen spread systemically in the same mice inoculated with PMN from thermally injured mice (TI-PMN). SCIDbgMN mice were shown to be greatly susceptible to sepsis caused by E. faecalis translocation, while orally infected E. faecalis did not spread into sepsis in the same mice that were previously inoculated with Mphi from unburned SCIDbg mice (resident Mphi). In contrast, orally infected E. faecalis spread systemically in SCIDbgMN mice inoculated with resident Mphi and TI-PMN, while all SCIDbgMN mice inoculated in combination with resident Mphi and PMN from unburned SCIDbg mice survived after the infection. After cultivation with TI-PMN in a dual-chamber transwell, resident Mphi converted to alternatively activated Mphi, which are inhibitory on the generation of classically activated Mphi (typical effector cells in host antibacterial innate immunities). TI-PMN were characterized as immunosuppressive PMN (PMN-II) with abilities to produce cc-chemokine ligand-2 and IL-10. These results indicate that PMN-II appearing in response to burn injury impair host antibacterial resistance against sepsis stemming from E. faecalis translocation through the conversion of resident Mphi to alternatively activated Mphi.     

Conditional macrophage ablation demonstrates that resident macrophages initiate acute peritoneal inflammation

The role played by resident macrophages (Mphi) in the initiation of peritoneal inflammation is currently unclear. We have used a conditional Mphi ablation strategy to determine the role of resident peritoneal Mphi in the regulation of neutrophil (PMN) recruitment in experimental peritonitis. We developed a novel conditional Mphi ablation transgenic mouse (designated CD11bDTR) based upon CD11b promoter-mediated expression of the human diphtheria toxin (DT) receptor. The murine DT receptor binds DT poorly such that expression of the human receptor confers toxin sensitivity. Intraperitoneal injection of minute (nanogram) doses of DT results in rapid and marked ablation of F4/80-positive Mphi populations in the peritoneum as well as the kidney, and ovary. In experimental peritonitis, resident Mphi ablation resulted in a dramatic attenuation of PMN infiltration that was rescued by the adoptive transfer of resident nontransgenic Mphi. Attenuation of PMN infiltration was associated with diminished CXC chemokine production at 1 h. These studies indicate a key role for resident peritoneal Mphi in sensing perturbation to the peritoneal microenvironment and regulating PMN infiltration.     

Failure of monocytes of trauma patients to convert to immature dendritic cells is related to preferential macrophage-colony-stimulating factor-driven macrophage differentiation

Following trauma, increased inflammatory monokine activation and depressed APC function can occur simultaneously. These contradictory monocyte (Mphi) dysfunctions could result if postinjury Mphi differentiation preferentially favored inflammatory macrophage (Mac) differentiation over development into the most potent APC, dendritic cells (DC). In this report, Mphi of trauma patients with a depressed MLR induction capacity are, for the first time, shown to be unable to differentiate in vitro to immature CD1a(+) DC under the influence of GM-CSF and IL-4. Trauma patient Mphi that retained MLR-inducing capacity had a nonsignificant reduction in DC differentiation capacity. Only patient Mphi populations with depressed differentiation to immature DC (iDC) demonstrated depressed IL-12 and IL-15 production and a continued reduced MLR induction capacity. Neither increased IL-10 production nor decreased CD11c(+) DC precursor numbers correlated with depressed Mphi-to-DC differentiation. Instead, these patients' APC-dysfunctional Mphi populations had increased expression of inflammatory Mac phenotypes (CD64(+), CD86(low), HLA-DR(low)) and up-regulated secretion of M-CSF. M-CSF combined with IL-6 inhibits Mphi-to-iDC differentiation and promotes Mphi-to-Mac differentiation by down-regulating GM-CSFR expression and increasing DC apoptosis. Both depressed GM-CSFR expression and increased Mphi iDC apoptosis, as well as increased expression of CD126 (IL-6R) and CD115 (M-CSFR), were detected in APC-defective patient Mphi. In vitro addition of anti-M-CSF enhanced the IL-4 plus GM-CSF-induced Mphi-to-DC differentiation of these patients. This suggests that, in trauma patients, enhanced Mphi-to-Mac differentiation with concomitant inhibited iDC development is partially due to increased circulating Mphi sensitivity to and production of M-CSF and contributes to postinjury immunoaberrations.     

Regulation of macrophage physiology by L-arginine: role of the oxidative L-arginine deiminase pathway

The L-arginine content of the extracellular fluid in sites of predominant macrophage infiltration is reduced below plasma levels due to the activity of macrophage-derived arginase. Investigation of the effects of altered L-arginine availability on macrophage physiology reveals that culture of rat peritoneal macrophages in media containing L-arginine in the concentrations present in inflammatory lesions (less than 0.1 mM) enhances activation-associated functions. In contrast, culture in the higher L-arginine concentrations found in standard tissue culture media (0.4 to 1.2 mM) suppresses most macrophage functions (superoxide production, phagocytosis, and protein synthesis). An exception is the tumor cytotoxicity of Corynebacterium parvum-elicited macrophages which is enhanced by culture in supraphysiologic concentrations of L-arginine. Work reported here investigated the mechanisms for these L-arginine-dependent effects and, more specifically, the role of the recently described oxidative L-arginine deiminase pathway in the regulation of macrophage physiology. Overnight culture of resident or C. parvum-elicited peritoneal macrophages in media containing increasing concentrations of L-arginine (6 microM to 1 mM) resulted in: inhibition of electron transport chain activity (resident and C. parvum-elicited macrophages), increased lactate production (resident macrophages), and decreased ATP content (resident and C. parvum-elicited macrophages). In line with these findings, viability was markedly decreased after 2 days of culture when the initial L-arginine concentration was greater than or equal to 0.1 mM. As shown before, increasing media concentrations of L-arginine were associated with suppression of superoxide production and cytotoxicity in resident macrophages, and with reduced superoxide production and increased cytotoxicity in C. parvum-elicited macrophages. All L-arginine-dependent metabolic and functional alterations, as well as the loss of viability, were prevented by NG-monomethyl-L-arginine, a specific inhibitor of the oxidative L-arginine deiminase pathway. These results demonstrate that flux of L-arginine through the oxidative L-arginine deiminase pathway results in the inhibition of oxidative metabolism in rat macrophages. This metabolic inhibition may, through alterations in the macrophage high energy phosphate stores, mediate the suppression of cell functions and result ultimately in cell death.     

In hepatocytes the regulation of NOS-2 activity at physiological l-arginine levels suggests a close link to the urea cycle

High-output synthesis of nitric oxide (NO) by the inducible isoform of NO-synthases (NOS-2) plays an important role in hepatic pathophysiological processes and may contribute to both organ protection and organ destruction during inflammatory reactions. As they compete for the same substrate, L-arginine, an interdependence of NOS-2 and arginase-1 has been repeatedly observed in cells where arginase-1 is cytokine-inducible. However, in hepatocytes, arginases are constitutively expressed and thus, their impact on hepatic NOS-2-derived NO synthesis as well as the influence of L-arginine influx via cationic amino acid transporters during inflammatory reactions are still under debate. Freshly isolated rat hepatocytes were cultured for 24h in the presence of various L-arginine concentrations with or without cytokine addition and nitrite and urea accumulation in culture supernatants was measured. We find that both, cytokine-induced NOS-2 and arginase activities strongly depend on extracellular L-arginine concentrations. When we competed for L-arginine influx via the cationic amino acid transporters by addition of L-lysine, we find a 60-70% inhibition of arginase activity without significant loss of NOS-2 activity. Addition of L-valine, as an arginase inhibitor, leads to a 25% increase in NO formation and an 80-90% decrease in arginase activity. Interestingly, product inhibition of arginase and competitive inhibition of CATs through the addition of L-ornithine leads to a highly significant increase in hepatocytic NOS-2 activity with a concomitant and complete abolishment of its dependence on extracellular L-arginine concentrations. In conclusion, hepatocytic NOS-2 activity shows a surprising pattern of dependence on exogenous L-arginine concentrations. Inhibition and competition experiments suggest a relatively tight link of NOS-2 and urea cycle activities. These data stress the hypothesis of a metabolon-like organization of the urea cycle together with NOS-2 in hepatocytes as excess L-ornithine will be metabolized to l-arginine and thereby increases NO production.     

The role of SIGNR1 and the beta-glucan receptor (dectin-1) in the nonopsonic recognition of yeast by specific macrophages

We recently demonstrated that the beta-glucan receptor Dectin-1 (betaGR) was the major nonopsonic beta-glucan receptor on macrophages (Mphi) for the yeast-derived particle zymosan. However, on resident peritoneal Mphi, we identified an additional mannan-inhibitable receptor for zymosan that was distinct from the Mphi mannose receptor (MR). In this study, we have studied the mannose-binding potential of murine Mphi and identified the dendritic cell-specific ICAM-3-grabbing nonintegrin homolog, SIGN-related 1 (SIGNR1), as a major MR on murine resident peritoneal Mphi. Both SIGNR1 and betaGR cooperated in the nonopsonic recognition of zymosan by these Mphi. When SIGNR1 was introduced into NIH3T3 fibroblasts or RAW 264.7 Mphi, it conferred marked zymosan-binding potential on these cells. However, in the nonprofessional phagocytes (NIH3T3), SIGNR1 was found to be poorly phagocytic, suggesting that other receptors such as betaGR may play a more dominant role in particle internalization on professional phagocytes. Binding of zymosan to RAW 264.7 Mphi expressing SIGNR1 resulted in TNF-alpha production. Treatment of RAW 264.7 Mphi expressing SIGNR1, which express low levels of betaGR, with beta-glucans had little effect on binding or TNF-alpha production, indicating that there was no absolute requirement for betaGR in this process. These studies have identified SIGNR1 as a major MR for fungal and other pathogens present on specific subsets of Mphi.     

Developmental changes in arginase expression and activity in the lung

Arginases compete with nitric oxide (NO) synthases for L-arginine as common substrate. Pulmonary vascular and airway diseases in which arginase activity is increased are associated with decreased NO production and reduced smooth muscle relaxation. The developmental patterns of arginase activity and type I and II isoforms expression in the lung have not been previously evaluated. Hypothesizing that lung arginase activity is developmentally regulated and highest in the fetus, we measured the expression of both arginase isoforms and total arginase activity in fetal, newborn, and adult rat lung, pulmonary artery, and bronchial tissue. In addition, intrapulmonary arterial muscle force generation was evaluated in the absence and presence of the arginase inhibitor Nomega-hydroxy-nor-L-arginine (nor-NOHA). Arginase II content, as well as total arginase activity, was highest in fetal rat lung, bronchi, and pulmonary arterial tissue and decreased with age (P<0.05), and its lung cell expression was developmentally regulated. In the presence of nor-NOHA, pulmonary arterial force generation was significantly reduced in fetus and newborn (P<0.01). No significant change in force generation was noted in bronchial tissue following arginase inhibition. In conclusion, arginase II is regulated developmentally, and both expression and activity are maximal during fetal life. We speculate that the maintenance of a high pulmonary vascular resistance and decreased lung NO production prenatally may, in part, be dependent on increased arginase expression and/or activity.     

MAP kinases differentially regulate the expression of macrophage hyperactivity after thermal injury

Thermal injury increases the capacity of macrophages (Mphi) to produce various inflammatory mediators, (i.e., Mphi hyperactivity), which is believed to be involved in the development of subsequent immunosuppression, sepsis, and multiple organ failure. The signal transduction pathways involved in the expression of Mphi hyperactivity post-burn, however, remain to be clearly elucidated. To study this C57BL/6 female mice were subjected to a 25% TBSA burn and splenic Mphis were isolated 7 days later. LPS-stimulated inflammatory mediator production and MAPK expression (P38 ERK 1/2 and JNK) were determined. Burn injury increased LPS-induced P38 MAPK, suppressed JNK activation and ERK 1/2 activation was unaltered. These changes in MAPK activation were paralleled by the increased production of PGE(2), TNF-alpha, IL-1beta, IL-6, and IL-10. Differential sensitivity to the inhibition of the MAPK pathways was observed with regard to the mediator evaluated and the presence or absence of burn injury. In general cytokine production in the burn group was in part resistant to the inhibition of a single MAPK pathway as compared with shams. Thus, burn injury increases cross-talk between the MAPKs pathways, suggesting that alterations MAPK activation and signal transduction contribute to the development Mphi hyperactivity post-injury.     

Inhibition of arginase I activity by RNA interference attenuates IL-13-induced airways hyperresponsiveness

Increased arginase I activity is associated with allergic disorders such as asthma. How arginase I contributes to and is regulated by allergic inflammatory processes remains unknown. CD4+ Th2 lymphocytes (Th2 cells) and IL-13 are two crucial immune regulators that use STAT6-dependent pathways to induce allergic airways inflammation and enhanced airways responsiveness to spasmogens (airways hyperresponsiveness (AHR)). This pathway is also used to activate arginase I in isolated cells and in hepatic infection with helminths. In the present study, we show that arginase I expression is also regulated in the lung in a STAT6-dependent manner by Th2-induced allergic inflammation or by IL-13 alone. IL-13-induced expression of arginase I correlated directly with increased synthesis of urea and with reduced synthesis of NO. Expression of arginase I, but not eosinophilia or mucus hypersecretion, temporally correlated with the development, persistence, and resolution of IL-13-induced AHR. Pharmacological supplementation with l-arginine or with NO donors amplified or attenuated IL-13-induced AHR, respectively. Moreover, inducing loss of function of arginase I specifically in the lung by using RNA interference abrogated the development of IL-13-induced AHR. These data suggest an important role for metabolism of l-arginine by arginase I in the modulation of IL-13-induced AHR and identify a potential pathway distal to cytokine receptor interactions for the control of IL-13-mediated bronchoconstriction in asthma.     

Cutting edge: differential effect of apoptotic versus necrotic tumor cells on macrophage antitumor activities.

Macrophages (Mphi) play essential roles both in tumor defense and normal tissue homeostasis by removal of transformed as well as damaged and disintegrating cells. Whereas tissue necrosis is known to provoke inflammatory responses, removal of apoptotic cells has been assumed to be immunologically inert. We now show that while Mphi exposure to necrotized tumor cells causes pronounced stimulation of Mphi antitumor activity, exposure of Mphi to apoptotic tumor cells in contrast results in impairment of Mphi-mediated tumor defense and even support of tumor cell growth. Given the fact that apoptosis is a consequence of various cancer treatment modalities, this may lead to a suppression of local antitumor reactions and thus actually counteract endogenous immune-mediated tumor defense mechanisms.     

Paclitaxel enhances macrophage IL-12 production in tumor-bearing hosts through nitric oxide.

Tumor-induced macrophages (Mphis) mediate immunosuppression, in part, through increased production of factors that suppress T cell responsiveness and underproduction of positive regulatory cytokines. Pretreatment of tumor-bearing host (TBH) Mphis with the anticancer agent paclitaxel (Taxol) partially reverses tumor-induced Mphi suppressor activity, suggesting that paclitaxel may restore TBH Mphi production of proimmune factors. Because paclitaxel demonstrates LPS-mimetic capabilities and increased production of the LPS-induced immunostimulatory cytokine IL-12 could account for enhanced T cell responsiveness, we investigated whether paclitaxel induces Mphi IL-12 production. Tumor growth significantly down-regulated Mphi IL-12 p70 production through selective dysregulation of IL-12 p40 expression. LPS stimulation failed to overcome tumor-induced dysregulation of p40 expression. In contrast, paclitaxel significantly enhanced both normal host and TBH Mphi IL-12 p70 production in vitro, although TBH Mphi IL-12 production was lower than that of similarly treated normal host Mphis. Paclitaxel enhanced p40 expression in a dose-dependent manner. Through reconstituted Mphi IL-12 expression, paclitaxel pretreatment relieved tumor-induced Mphi suppression of T cell alloreactivity. Blocking Mphi NO suppressed paclitaxel's ability to induce IL-12 production. This suggests that paclitaxel-induced activities may involve a NO-mediated autocrine induction pathway. Collectively, these data demonstrate that paclitaxel restores IL-12 production in the TBH and ascribe a novel immunotherapeutic component to the pleiotropic activities of NO. Through its capacity to induce IL-12 production, paclitaxel may contribute to the correction of tumor-induced immune dysfunction.     

Chitosan gallate as potential antioxidant biomaterial

Chitosan gallate were synthesized using a free radical-induced grafting reaction. Chitosan gallate showed enhanced water-solubility compared to plain chitosan, and exhibited good thermal stability. The IC₅₀ value of chitosan gallate against 2,2-diphenyl-1-picrylhydrazyl (DPPH) was 17.86 μg/mL. In addition, chitosan gallate effectively inhibited the generation of intracellular reactive oxygen species (ROS), and also suppressed lipid peroxidation in RAW264.7 macrophage cells. Chitosan gallate also exhibited the protection effect on genomic DNA damage by induced hydroxyl radical, and up-regulated the protein expression of antioxidant enzymes including superoxide dismutase-1 and glutathione reductase under H₂O₂-mediated oxidative stress in RAW264.7 macrophage cells. These results indicate that chitosan gallate might be potential antioxidant biomaterials.     

Inhibition of phosphodiesterase 4 amplifies cytokine-dependent induction of arginase in macrophages

Arginase is greatly elevated in asthma and is thought to play a role in the pathophysiology of this disease. As inhibitors of phosphodiesterase 4 (PDE4), the predominant PDE in macrophages, elevate cAMP levels and reduce inflammation, they have been proposed for use in treatment of asthma and chronic obstructive pulmonary disease. As cAMP is an inducer of arginase, we tested the hypothesis that a PDE4 inhibitor would enhance macrophage arginase induction by key cytokines implicated in asthma and other pulmonary diseases. RAW 264.7 cells were stimulated with IL-4 or transforming growth factor (TGF)-beta, with and without the PDE4 inhibitor rolipram. IL-4 and TGF-beta increased arginase activity 16- and 5-fold, respectively. Rolipram alone had no effect but when combined with IL-4 and TGF-beta synergistically enhanced arginase activity by an additional 15- and 5-fold, respectively. The increases in arginase I protein and mRNA levels mirrored increases in arginase activity. Induction of arginase II mRNA was also enhanced by rolipram but to a much lesser extent than arginase I. Unlike its effect in RAW 264.7 cells, IL-4 alone did not increase arginase activity in human alveolar macrophages (AM) from healthy volunteers. However, combining IL-4 with agents to induce cAMP levels induced arginase activity in human AM significantly above the level obtained with cAMP-inducing agents alone. In conclusion, agents that elevate cAMP significantly enhance induction of arginase by cytokines. Therefore, consequences of increased arginase expression should be evaluated whenever PDE inhibitors are proposed for treatment of inflammatory disorders in which IL-4 and/or TGF-beta predominate.     

Th1/Th2-regulated expression of arginase isoforms in murine macrophages and dendritic cells.

Activated murine macrophages metabolize arginine by two alternative pathways involving the enzymes inducible NO synthase (iNOS) or arginase. The balance between the two enzymes is competitively regulated by Th1 and Th2 T helper cells via their secreted cytokines: Th1 cells induce iNOS, whereas Th2 cells induce arginase. Whereas the role of macrophages expressing iNOS as inflammatory cells is well established, the functional competence of macrophages expressing arginase remains a matter of speculation. Two isoforms of mammalian arginases exist, hepatic arginase I and extrahepatic arginase II. We investigated the regulation of arginase isoforms in murine bone marrow-derived macrophages (BMMPhi) in the context of Th1 and Th2 stimulation. Surprisingly, in the presence of either Th2 cytokines or Th2 cells, we observe a specific induction of the hepatic isoform arginase I in BMMPhi. Induction of arginase I was shown on the mRNA and protein levels and obeyed the recently demonstrated synergism among the Th2 cytokines IL-4 and IL-10. Arginase II was detectable in unstimulated BMMPhi and was not significantly modulated by Th1 or Th2 stimulation. Similar to murine BMMPhi, murine bone marrow-derived dendritic cells, as well as a dendritic cell line, up-regulated arginase I expression and arginase activity upon Th2 stimulation, whereas arginase II was never detected. In addition to revealing the unexpected expression of arginase I in the macrophage/monocyte lineage, these results uncover a further intriguing parallelism between iNOS and arginase: both have a constitutive and an inducible isoform, the latter regulated by the Th1/Th2 balance.     

Modulation of phagocytosis of apoptotic neutrophils by supernatant from dexamethasone-treated macrophages and annexin-derived peptide Ac(2-26)

Phagocytic clearance of apoptotic leukocytes plays an important role in the resolution of inflammation. The glucocorticoid-inducible protein annexin 1 and annexin 1-derived peptides show potent anti-inflammatory responses in acute and chronic inflammation. In this study, we report that the annexin 1-derived peptide (Ac(2-26)) significantly stimulates nonphlogistic phagocytosis of apoptotic polymorphonuclear leukocytes (PMNs) by human monocyte-derived macrophages (Mphi). Peptide Ac(2-26)-stimulated phagocytosis is accompanied by rearrangement of the Mphi actin cytoskeleton. To investigate the potential role of endogenous annexin on clearance of apoptotic cells, Mphi were cultured for 5 days in the presence of dexamethasone. Supernatants collected from dexamethasone-treated Mphi significantly enhanced the ability of naive Mphi to engulf apoptotic PMNs. This effect was blocked by an annexin blocking Ab, by immunodepletion of the supernatants, and by the formyl peptide receptor/lipoxin receptor antagonist Boc1. In addition, we show that bone marrow-derived Mphi from annexin 1-null mice present a 40% decreased phagocytosis of apoptotic PMNs compared with cells taken from littermate controls. In conclusion, these results emphasize the pivotal role of annexin 1 as mediator for clearance of apoptotic cells and expand its potential therapeutic role in controlling inflammatory diseases.     

Effect of adrenalectomy on rat peritoneal macrophage response

Glucocorticoid hormones are important for vital functions and act to modulate inflammatory and immune responses. In contrast to other hormonal systems no endogenous mediators have been identified that can directly counter-regulate their potent anti-inflammatory and immunosuppressive properties. Glucocorticoids are known to interfere with the ability of the macrophage not only to induce and amplify an immune response but also to inhibit macrophage inflammatory effector functions. Although the actual immunocompetence of animals undergoing endocrine gland ectomy has never been directly studied, there is no doubt that adrenal hormones are deeply involved in the development and maintenance of the immunitory functions and this may in turn influence the inflammatory reaction. To study the effect of endogenous glucocorticoids on the functions of rat peritoneal macrophages and induction of humoral immune response we observed some of the rat peritoneal macrophage effector functions, provided that endogenous glucocorticoids are depicted by adrenalectomy. The mean phagocytic index (PI) of control macrophage (Mphi) is increased from 23,825 +/- 427 to 31,895 +/- 83 after adrenalectomy (P < or = 0.001). Intracellular killing capacity in control cell is 82% which is found to be 73% in case of adrenalectomised cell (p < 0.05). The amount of nitric oxide released from control Mphi 20.25 +/- 1 microM following adrenalectomy shows the amount of nitric oxide release was 18.25 microM (p < or = 0.01 ). The percentage of DNA fragmentation in control Mphi was 68.82 +/- 4 which was reduced to 56.76 +/- 1 after adrenalectomy (p < or = 0.01). In sheep red blood cell (SRBC) immunised and adrenalectomised animal, agglutination titre was obtained at lowest antibody concentration (1 : 128) whereas serum from SRBC immunised normal rats showed early agglutination (1: 32). Endogenous glucocorticoid depleted rats show enhanced phagocytic capacity, antibody raising capacity as well as on the other hand adrenal hormone insufficiency reduces the intracellular killing capacity, nitric oxide (NO) release, improper cell maturation and heightens the probability of infection. These observations demonstrate a counter-regulatory system via glucocorticoid that functions to control inflammatory and immune responses.     

壳聚糖/ 魔芋葡甘露聚糖复合膜体内外促创面愈合研究

目的:制备壳聚糖/魔芋葡甘露聚糖复合膜,研究其促创面愈合作用。方法:壳聚糖溶液和魔芋葡甘露聚糖溶液混合后冷冻干燥制成复合膜。扫描电镜观察膜的形态和孔径,并研究比较膜的吸水率,水蒸气透过率,拉伸强度,断裂伸长率和体外降解率。建立大鼠皮肤损伤模型,敷以复合膜治疗,比较创面愈合率,观察创面组织染色结果,评价复合膜的促创面愈合作用。结果:壳聚糖/魔芋葡甘露聚糖复合膜具有三维网状结构,壳聚糖复合魔芋葡甘露聚糖后,膜的吸水率、拉伸强度和断裂伸长率提高,体外降解加速,水蒸气透过率改善。愈合实验表明壳聚糖/魔芋葡甘露聚糖膜具有促进创面愈合作用。结论:壳聚糖/魔芋葡甘露聚糖复合膜制备工艺简单,能有效促进创面愈合,具有成为创伤敷料的潜力。     

12/15-Lipoxygenase regulates the inflammatory response to bacterial products in vivo

The peritoneal macrophage (Mphi) is the site of greatest 12/15-lipoxygenase (12/15-LOX) expression in the mouse; however, its immunoregulatory role in this tissue has not been explored. Herein, we show that 12/15-LOX is expressed by 95% of resident peritoneal CD11b(high) cells, with the remaining 5% being 12/15-LOX(-). 12/15-LOX(+) cells are phenotypically defined by high F4/80, SR-A, and Siglec1 expression, and enhanced IL-10 and G-CSF generation. In contrast, 12/15-LOX(-) cells are a dendritic cell population. Resident peritoneal Mphi numbers were significantly increased in 12/15-LOX(-/-) mice, suggesting alterations in migratory trafficking or cell differentiation in vivo. In vitro, Mphi from 12/15-LOX(-/-) mice exhibit multiple abnormalities in the regulation of cytokine/growth factor production both basally and after stimulation with Staphylococcus epidermidis cell-free supernatant. Resident adherent cells from 12/15-LOX(-/-) mice generate more IL-1, IL-3, GM-CSF, and IL-17, but less CCL5/RANTES than do cells from wild-type mice, while Staphylococcus epidermidis cell-free supernatant-elicited 12/15-LOX(-/-) adherent cells release less IL-12p40, IL-12p70, and RANTES, but more GM-CSF. This indicates a selective effect of 12/15-LOX on peritoneal cell cytokine production. In acute sterile peritonitis, 12/15-LOX(+) cells and LOX products were cleared, then reappeared during the resolution phase. The peritoneal lavage of 12/15-LOX(-/-) mice showed elevated TGF-beta1, along with increased immigration of monocytes/Mphi, but decreases in several cytokines including RANTES/CCL5, MCP-1/CCL2, G-CSF, IL-12-p40, IL-17, and TNF-alpha. No changes in neutrophil or lymphocyte numbers were seen. In summary, endogenous 12/15-LOX defines the resident MPhi population and regulates both the recruitment of monocytes/Mphi and cytokine response to bacterial products in vivo.