猪苓多糖对巨噬细胞一氧化氮生成和细胞内还原型谷胱甘肽的影响

本文观察了猪苓多糖 (PPS )对小鼠腹腔巨噬细胞一氧化氮 (NO )生成和细胞内还原型谷胱甘肽 (GSH )的影响。结果显示 :(1)PPS对小鼠腹腔巨噬细胞NO生成具有明显的促进作用 ;(2 )细胞内GSH浓度随NO生成增加而减少 ;(3)这些作用能被NO生成抑制剂L NMMA所抑制。结果表明PPS能促进小鼠腹腔巨噬细胞NO生成 ,并同时消耗细胞内GSH。提示细胞内GSH可能起到调节巨噬细胞NO生成和保护宿主细胞免受NO介导的细胞毒作用。     

Intracellular Trafficking of Bordetella pertussis in Human Macrophages

Although Bordetella pertussis has been observed to survive inside macrophages, its ability to resist or evade degradation in phagolysosomes has not been defined. We here investigated the trafficking of B. pertussis upon entry into human macrophages. During the first hours following phagocytosis, a high percentage of bacteria were destroyed within acidic compartments positive for the lysosome-associated membrane proteins (LAMP). However, roughly one-fourth of the bacteria taken up evade this initial killing event, remaining in nonacidic compartments. Forty-eight hours after infection, the number of intracellular bacteria per cell increased, suggesting that B. pertussis is capable of replicating in this type of compartment. Viable bacteria accumulated within phagosomal compartments positive for the early endosomal marker Rab5 but not the late endosomal marker LAMP. Moreover, B. pertussis-containing phagosomes acquired exogenously added transferrin, indicating that intracellular bacteria have access to extracellular components and essential nutrients via the host cell recycling pathway. Overall, these results suggest that B. pertussis survives and eventually replicates in compartments with characteristics of early endosomes, potentially contributing to its extraordinary ability to persist within hosts and populations.Bordetella pertussis colonizes the human respiratory tract, causing a disease known as whooping cough or pertussis, which affects around 4 million people worldwide and causes more than 300,000 deaths each year. Despite high vaccination rates, whooping cough remains a serious threat to human health and its incidence has been increasing in recent years in vaccinated populations. Although some potential contributors to initial colonization have been described, the mechanisms that allow this pathogen to evade immune clearance and to cause the extraordinarily prolonged disease known in China as Bai Ri Ke (100-day cough) are not known.B. pertussis expresses a number of potent virulence factors, adhesins, and toxins (23) with known or predicted roles during infection. Although B. pertussis is described as an extracellular pathogen, several studies indicate that the immunomodulatory properties of several of these virulence factors enable the bacterium to persist within epithelial cells and leukocytes (1, 3, 22, 24), leading to speculation that the infection might also comprise an intracellular stage. The dual extra- and intracellular locations of B. pertussis are also consistent with the reported need for both cellular and humoral immune responses for bacterial elimination from the respiratory tract (12, 17, 33, 38).It is presumed that macrophages play an important role in the clearance of B. pertussis (21). However, in vitro studies indicated that B. pertussis is capable of surviving intracellularly in human macrophages for several days in the absence of opsonins (11). Moreover, B. pertussis was found viable in alveolar macrophage cells of mice for more than 21 days after infection (16). These observations have led to speculation that alveolar macrophages might represent an intracellular niche for B. pertussis (16, 41). The recovery of viable B. pertussis from human hosts several weeks after infection (19, 30) and the observation of B. pertussis within pulmonary alveolar macrophages of HIV-infected children (7) and in infants with confirmed B. pertussis pneumonia (28) provide support for this theory.Efforts to characterize the interaction between B. pertussis and human macrophages have been mainly focused on B. pertussis adherence. Several B. pertussis virulence factors facilitate interaction with phagocytes. B. pertussis fimbriae mediate the binding to the very late antigen 5 receptor on monocytes and macrophages, inducing the upregulation of complement receptor 3 (CR3: CD11b/CD18) (14). CR3 expression is further upregulated by pertussis toxin and filamentous hemagglutinin (FHA) (18, 42). It has been demonstrated that CR3 serves as a docking molecule for B. pertussis binding by FHA (18, 31), which eventually leads to B. pertussis uptake in a nonbactericidal way (15). However, little is known about the fate of B. pertussis inside macrophages. Recent studies by our group showed that neutrophil uptake of B. pertussis in the absence of specific antibodies leads to the failure of lysosomal maturation and bacterial clearance (20). These observations are intriguing evidence that B. pertussis has mechanisms that can allow for evasion of phagolysosome biogenesis. However, short-lived neutrophils are unlikely to provide a prolonged reservoir of bacteria, and evasion of phagolysosome biogenesis in macrophages appears to be an important aspect of the persistence of many other pathogens (9, 10, 29, 40).The aim of this study was to determine the fate of B. pertussis following phagocytosis by macrophages. Although many ingested bacteria were rapidly killed by macrophages, a significant fraction of internalized B. pertussis was capable of evading phagosome-lysosome fusion, surviving for days and eventually replicating in nonacidic compartments with characteristics of early endosomes. These results reveal a pathway that may contribute to both the extraordinarily long persistence of the coughing illness caused by B. pertussis and its ability to persist within largely immune populations.     

Stimulation of Nitric Oxide Production in Macrophages by Babesia bovis

Gamma interferon (IFN-γ)-activated macrophages are believed to play a key role in resistance to Babesia bovis through parasite suppression by macrophage secretory products. However, relatively little is known about interactions between this intraerythrocytic parasite and the macrophages of its bovine host. In this study, we examined the in vitro effect of intact and fractionated B. bovis merozoites on bovine macrophage nitric oxide (NO) production. In the presence of IFN-γ, B. bovis merozoites stimulated NO production, as indicated by the presence of increased l-arginine-dependent nitrite (NO₂⁻) levels in culture supernatants of macrophages isolated from several cattle. The merozoite crude membrane (CM) fraction stimulated greater production of NO, in a dose-dependent manner, than did the merozoite homogenate or the soluble, cytosolic high-speed supernatant fraction. Stimulation of NO production by CM was enhanced by as little as 1 U of IFN-γ per ml of culture medium. Upregulation of inducible NO synthase mRNA in bovine macrophages by either B. bovis-parasitized erythrocytes and IFN-γ or CM was also observed. B. bovis-specific T-helper lymphocyte culture supernatants, all of which contained IFN-γ, were also found to induce l-arginine-dependent NO₂⁻ production. Supernatants that induced the highest levels of NO also contained biologically active TNF. These results show that B. bovis merozoites and antigen-stimulated B. bovis-immune T cells can induce the production of NO, a molecule implicated in both protection and pathologic changes associated with hemoprotozoan parasite infections.Bovine babesiosis is an economically important tick-borne disease of cattle that is caused by intraerythrocytic apicomplexan parasites of the genus Babesia. Babesia bovis-infected erythrocytes undergo sequestration by attachment to capillary endothelium in a manner reminiscent of the most severe form of human malaria, caused by Plasmodium falciparum; this results in organ damage, cerebral dysfunction, and pulmonary edema (58). It has been hypothesized that the severe organ abnormalities that occur during acute B. bovis infection, similar to those observed during experimental malaria, are mediated in part by inflammatory cytokines, including gamma interferon (IFN-γ) and tumor necrosis factor (TNF), and nitric oxide (NO) (58).Although activation of macrophages could lead to immunopathological consequences, macrophages are also believed to be important for immunity to B. bovis and other intraerythrocytic parasites via removal of parasitized erythrocytes by phagocytosis and as antigen-presenting cells (APC) for T-helper (Th) lymphocytes. Furthermore, macrophage secretory products have been shown to inhibit the growth of P. falciparum and B. bovis in vitro (24, 34). When generated by chemical donors or activated macrophages in vitro, NO and its reactive nitrogen intermediate derivatives were shown to inhibit intracellular parasites including Leishmania major, P. falciparum, and B. bovis (22, 23, 27, 40, 53, 54).Studies in mice with B. microti, P. yoelii, P. vinckei, and P. chabaudi demonstrated that IFN-γ, TNF-α, and TNF-β are important components of immunity to these parasites (3, 15, 32, 44, 47). IFN-γ facilitates the phagocytosis of P. falciparum-infected erythrocytes by human macrophages (33, 35). In addition, parasite-specific, IFN-γ-producing human CD4⁺ Th-cell clones inhibited the growth of P. falciparum in the presence of adherent peripheral blood mononuclear cells (PBMC) in vitro (18, 37). The protective role of TNF-α appears to depend on the timing of its appearance, which may partially explain the paradoxical roles of TNF in protection and immunopathology. In resistant C57BL/6 mice, TNF-α appeared early during P. chabaudi infection, whereas in susceptible A/J mice, high levels of TNF-α were observed only late in infection, just preceding death (25).Experiments performed during the past decade showed that malarial parasites and secreted toxins induced TNF-α in human and murine macrophages and inducible NO synthase (iNOS) in murine macrophages. Macrophages exposed in vitro to P. yoelii, P. berghei, or P. falciparum produced TNF-α, which was enhanced by IFN-γ (4, 36, 50, 51). Similarly, P. falciparum extract, in the presence of IFN-γ, stimulated murine macrophages to produce both TNF-α and NO (31, 41). However, the interpretation of these results has been questioned by the recent discovery that many continuously cultured strains of P. falciparum are contaminated with Mycoplasma species (56). Mycoplasma organisms induce TNF-α and other inflammatory mediators in murine, human, and bovine macrophages (28–30, 56), and experiments with Mycoplasma-free P. falciparum are being repeated to verify that the induction of inflammatory cytokines and NO was due to the parasite itself (43).Several observations support the hypothesis that IFN-γ produced by effector Th cells plays a key role in protection against babesiosis (10). In cattle, IFN-γ regulates B-cell synthesis of the opsonizing immunoglobulin G2 subclass (17). Parasite-specific Th-cell clones isolated from B. bovis-immune cattle produce IFN-γ and TNF (11, 14). Bovine macrophages have upregulated expression of iNOS when activated by IFN-γ in the presence of bacterial LPS (2) or TNF-α (20). Thus, the induction of macrophage iNOS by either B. bovis extracts or antigen-activated T cells would be indicative of macrophage activation and a potential babesiacidal effector mechanism. Conversely, overproduction of NO could also contribute to the pathologic changes associated with infection, including cerebral babesiosis.This study was undertaken to determine if bovine macrophages produce NO when exposed to B. bovis in the presence or absence of IFN-γ. Potential Mycoplasma contamination of B. bovis cultures was ruled out by a PCR-based assay. We report, for the first time, that bovine macrophages produce NO following in vitro exposure to B. bovis merozoites or a membrane-enriched fraction. The effect of different concentrations of either IFN-γ or B. bovis on NO production was also examined. Furthermore, the functional relevance of B. bovis-specific Th cells that produce IFN-γ and TNF was evaluated by the determining the ability of Th-cell supernatants to stimulate NO production. Induction of iNOS was confirmed by demonstrating reduced nitrite (NO₂⁻) levels in the presence of N^G-monomethyl-l-arginine (l-NMMA) and enhanced levels of iNOS steady-state mRNA in macrophages cultured with B. bovis.     

Evaluation of Nitric Oxide Production by Leishmania Infantum-infected Dog Macrophages

Protozoa of the genus Leishmania (L.) infect reticuloendothelial cells of several mammalian species, including dogs, in which they often give rise to a chronic, not self-healing visceral disease Since the parasitocidal mechanism of macrophages towards Leishmania in dog has not yet been well investigated, in this work we have evaluated in Leishmania infantum-infected macrophage cultures from 10 healthy dogs, killing capacity and nitric oxide (NO) production, in terms of nitrite (NO₂^-) levels. Parallel experiments were performed on macrophages stimulated with both Concanavalin A (ConA)-activated PBMC supematants and Salmonella typhimurium lipopolysaccharide (LPS), and in the same conditions, but in the presence of the NO synthase inhibitor L-N monomethylarginine (L-NMMA). In L. infantum-infected macrophages, nitric oxide production was observed at a concentration significantly higher after stimulation with both Con A-activated PBMC supematants and LPS than that observed in uninfected cells cultured in medium alone, or infected cells unstimulated or stimulated by PBMC supematants or LPS alone, respectively. Moreover, NO production was abolished in the presence of the NO synthase inhibitor L-NMMA. Finally, killing of Leishmania by macrophages was significantly reduced in the presence of L-NMMA.     

The Influence of Water-Soluble Polysaccharides of Crataegus sanguinea Pall. on Nitric Oxide Production by Macrophages

Bulletin of Experimental Biology and Medicine - The in vitro addition of water-soluble polysaccharides isolated from the leaves of Crataegus sanguinea Pall. to culture of mouse peritoneal...     

The Mannose Receptor Mediates Uptake of Pathogenic and Nonpathogenic Mycobacteria and Bypasses Bactericidal Responses in Human Macrophages

The mannose receptor (MR) is involved in the phagocytosis of pathogenic microorganisms. Here we investigated its role in the bactericidal functions of human monocyte-derived macrophages (MDMs), using (i) trimannoside-bovine serum albumin (BSA)-coated latex beads and zymosan as particulate ligands of the MR, and (ii) mannan and mannose-BSA as soluble ligands. We show that phagocytosis of mannosylated latex beads did not elicit the production of O₂⁻. Zymosan, which is composed of α-mannan and β-glucan, was internalized by the MR and a β-glucan receptor, but the production of O₂⁻ was triggered only by phagocytosis through the β-glucan receptor. Activation and translocation of Hck, a Src family tyrosine kinase located on lysosomes, has previously been used as a marker of fusion between lysosomes and phagosomes in human neutrophils. In MDMs, Hck was activated and recruited to phagosomes containing zymosan later than LAMP-1 and CD63. Phagosomes containing mannosylated latex beads fused with LAMP-1 and CD63 vesicles but not with the Hck compartment, and the kinase was not activated. We also demonstrate that the MR was unable to distinguish between nonpathogenic and pathogenic mycobacteria, as they were internalized at similar rates by this receptor, indicating that this route of entry cannot be considered as a differential determinant of the intracellular fate of mycobacteria. In conclusion, MR-dependent phagocytosis is coupled neither to the activation of NADPH oxidase nor to the maturation of phagosomes until fusion with the Hck compartment and therefore constitutes a safe portal of entry for microorganisms.     

香菇多糖对小鼠腹腔巨噬细胞一氧化氮生成的影响及其机理

为进一步探讨香菇多糖（Lentinan,LTN）的免疫调节和抗肿瘤作用机理,本实验研究了LTN对小鼠腹腔巨噬细胞一氧化氮（NO）生成和诱导型一氧化氮合酶（iNOS）的影响。结果显示,LTN能明显促进小鼠腹腔巨噬细胞NO生成,并且同干扰素-γ（IFN－γ）具有协同促进作用。结果还表明,LTN的这一促进作用能被RNA转录抑制剂放线菌素D、蛋白质合成抑制剂放线菌酮和一氧化氮合酶（NOS）抑制剂L－NMA所抑制。提示LTN的免疫调节和抗肿瘤作用机理可能与其诱导巨噬细胞iNOS合成、促进NO生成有关。     

Cyclophosphamide Decreases Nitrotyrosine Formation and Inhibits Nitric Oxide Production by Alveolar Macrophages in Mycoplasmosis

We previously reported that congenic C57BL/6 inducible nitric oxide synthase(-/-) (iNOS(-/-)) mice infected with Mycoplasma pulmonis developed higher bacterial numbers and lung lesion scores than C57BL/6 iNOS(+/+) controls but had similar lung nitrotyrosine levels. The present studies investigated the role of inflammatory cells in nitrotyrosine formation during mycoplasmal infection. iNOS(+/+) and iNOS(-/-) mice were injected with cyclophosphamide (CYP) and inoculated with 10(7) CFU of M. pulmonis. CYP pretreatment of M. pulmonis-infected iNOS(+/+) and iNOS(-/-) mice reduced polymorphonuclear cells (PMNs) within bronchoalveolar lavages (BALs) by 88 and 72%, respectively, and whole-lung myeloperoxidase levels by 80 and 78%, respectively, at 72 h postinfection but did not alter the number of alveolar macrophages (AMs) in BALs. CYP treatment also significantly decreased nitrate and nitrite (NOx) levels in BALs and plasma of infected iNOS(+/+) mice, whereas neither CYP nor mycoplasmal infection altered NOx in iNOS(-/-) mice. CYP reduced lung nitrotyrosine levels in both iNOS(+/+) and iNOS(-/-) mice to uninfected-control levels as shown by immunohistochemical staining and enzyme-linked immunosorbent assay and inhibited mycoplasmal killing by iNOS(+/+) mice in vivo. CYP inhibited the production of gamma interferon-inducible NOx by iNOS(+/+) AMs in vitro but did not alter the number of iNOS-positive AMs, as detected by immunocytochemistry. In addition, AMs from CYP-treated iNOS(+/+) mice had significantly decreased ability to kill mycoplasmas in vitro. These results demonstrate that reactive species generated by inflammatory cells as well as PMN myeloperoxidase are important contributors to nitrotyrosine formation during mycoplasmal infection and that treatment with CYP decreases NO* production by AMs and inhibits mycoplasmal killing.     

Phlebotomus papatasi Saliva Inhibits Protein Phosphatase Activity and Nitric Oxide Production by Murine Macrophages

Leishmania parasites, transmitted by phlebotomine sand flies, are obligate intracellular parasites of macrophages. The sand fly Phlebotomus papatasi is the vector of Leishmania major, a causative agent of cutaneous leishmaniasis in the Old World, and its saliva exacerbates parasite proliferation and lesion growth in experimental cutaneous leishmaniasis. Here we show that P. papatasi saliva contains a potent inhibitor of protein phosphatase 1 and protein phosphatase 2A of murine macrophages. We further demonstrate that P. papatasi saliva down regulates expression of the inducible nitric oxide synthase gene and reduces nitric oxide production in murine macrophages. Partial biochemical characterization of the protein phosphatase and nitric oxide inhibitor indicated that it is a small, ethanol-soluble molecule resistant to boiling, proteolysis, and DNase and RNase treatments. We suggest that the P. papatasi salivary protein phosphatase inhibitor interferes with the ability of activated macrophages to transmit signals to the nucleus, thereby preventing up regulation of the induced nitric oxide synthase gene and inhibiting the production of nitric oxide. Since nitric oxide is toxic to intracellular parasites, the salivary protein phosphatase inhibitor may be the mechanism by which P. papatasi saliva exacerbates cutaneous leishmaniasis.     

Growth of Cryptococcus neoformans Within Human Macrophages In Vitro

Macrophages cultured from human peripheral blood monocytes were infected with Cryptococcus neoformans in vitro. Although C. neoformans were actively ingested, there was no detectable intracellular killing by macrophages. Over 2 days or more, intracellular fungi grew more rapidly than a corresponding inoculum of extracellular cryptococci growing in tissue culture medium containing human serum. Macrophages were induced to develop into cells which appeared to be activated by morphological and phagocytic criteria. However, these activated cells did not acquire an ability to kill or inhibit intracellular growth of C. neoformans. There were no detectable differences between macrophages from normal subjects and those from cryptococcosis patients.     

Nitric Oxide Synthase in Human Parathyroid Glands and Parathyroid Adenomas

Nitric oxide (NO) is a novel gaseous intercellular transmitter thought to play important physiological roles in the regulation of blood flow and hormone secretion in, for example, the pituitary, the thyroid, and the endocrine pancreas. Whether nitric oxide synthase (NOS) is present in the human parathyroid glands has not yet been demonstrated. In the present study, histologically normal, but functionally suppressed human parathyroid glands and parathyroid adenomas from patients with primary hyperparathyroidism were investigated by immunocytochemistry with antibodies against neuronal NOS and by reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry. We also used H&E to identify the NOS-immunoreactive cells. Immunocytochemistry demonstrated the presence of neuronal-type NOS in a subpopulation of glandular cells, identified as oxyphilic cells, in both normal parathyroid glands and adenomas. NADPH-diaphorase staining visualized NOS in the endothelium of blood vessels and in glandular cells, corresponding to those containing immunoreactive NOS. In addition, we found NADPH-diaphorase staining in many chief cells. Our results indicate that both glandular cells and vascular endothelium in human parathyroid glands and adenomas express NOS. There is thus a morphological substrate for locally produced NO that may be involved in the regulation of parathyroid blood flow and hormone secretion.     

Induction of Gamma Interferon and Nitric Oxide by Truncated Pneumolysin That Lacks Pore-Forming Activity

Pneumolysin (PLY), an important virulence factor of Streptococcus pneumoniae, is known to exert various effects on the host immune cells, including cytokine induction, in addition to its known cytolytic activity as a member of the thiol-activated cytolysins. It is of interest to determine whether cytolytic activity is involved in triggering the cytokine production. In this study, we constructed full-length recombinant PLY and noncytolytic truncated PLYs with C-terminal deletions to examine the response of spleen cells to these PLY preparations. When cytolytic activity was blocked by treatment with cholesterol, full-length PLY was capable of inducing gamma interferon (IFN-gamma) production. Truncated PLYs that originally exhibited no cytolytic activity were also active in IFN-gamma induction. Therefore, the IFN-gamma-inducing ability of PLY appeared to be independent of the cytolytic activity. Furthermore, IFN-gamma-inducing preparations were also capable of inducing nitric oxide synthase expression and nitric oxide (NO) production, and the addition of neutralizing antibody to IFN-gamma abolished the NO production. These results clearly demonstrated that PLY is capable of inducing IFN-gamma production in spleen cells by a mechanism different from pore formation and that the induced IFN-gamma stimulates NO production. These findings were discussed with reference to the contribution of PLY to the virulence of S. pneumoniae in vivo.     

Ultrastructural Study of the Behavior of Macrophages Toward Parasitic Mycobacteria

Mycobacterium lepraemurium and M. microti (causal agent of vole tuberculosis) were isolated from tissues of experimentally infected mice and used to infect normal mouse peritoneal macrophage cultures. The cellular response to these bacteria up to 4 days after infection was studied quantitatively by electron microscopy. Prelabeling with ferritin was used to facilitate observation of fusion between secondary lysosomes in the cells and phagosomes containing the bacteria. All bacteria were intraphagosomal, and a high proportion of them was morphologically "intact." Nearly all phagosomes containing morphologically damaged (presumed nonviable) bacteria also contained ferritin, having fused with secondary lysosomes. Fusion of lysosomes had also occurred with most phagosomes containing intact M. lepraemurium but was infrequent with phagosomes containing intact M. microti. This tendency of multiplying mycobacteria of the tubercle type to avoid contact with lysosomal contents has already been reported for M. tuberculosis strain H37Rv. The different intracellular circumstances of the parasites may reflect different means of intracellular survival.     

Fibronectin Promotes Binding But Not Ingestion of Agarose Beads by Mouse Macrophages and Human Monocytes

We have examined to what extent human fibronectin associated with agarose beads with a 5- to 10-μm diameter mediates binding and uptake of the heads by mouse macrophages and human monocytes. Native agarose beads preincubated with ¹²⁵I-fibronectin were neither associated with nor taken up by mouse macrophages after 30 min of incubation under serum-free conditions. When fibronectin was cross-linked to cyanogen bromide-activated agarose heads or incubated with gelatinized heads, this resulted in a significant increase in particle binding by macrophages and monocytes as compared with gelatinized beads, whereas the fraction of cells with ingested particles remained unaltered. Native agarose heads activated by cyanogen bromide and treated with ethanolamine were to a greater extent associated with and taken up by phagocytes than fibronectin- or gelatin-coated heads. Our results indicate thai fibronectin acts as an adhesive glycoprotein and not as an opsonin. Since agarose beads are activators of the alternative pathway of complement, and fibronectin is reported to bind to factor C3, we speculate that cell-derived C3b is bound to the beads and fibroneetin-coaled beads arc ingested by the phagocytes via complement C3b receptors on the cells.     

一氧化氮与活化的小鼠腹腔巨噬细胞细胞毒作用关系的研究

本文选用Raji和K562两种细胞株作靶细胞,以LPS和IFN-γ作为巨噬细胞(MΦ)的激活剂,研究了一氧化氮(NO)在活化的小鼠腹腔巨噬细胞(PEMΦ)细胞毒中的作用以及靶细胞对MΦ合成NO的影响.结果表明,PEMΦ被激活后,合成NO量大为增加,并对Raji和K562两种靶细胞表现出很高的细胞毒效应;加入NO合酶抑制剂L-NMMA,PEMΦ对Raji的杀伤作用受到显著抑制,而对K562的细胞毒作用则不受影响.此外,在实验条件下,Raji细胞的存在可促进PEMΦ产生NO,而K562细胞则有削弱PEMΦ合成NO的倾向.