Effect of C-reactive protein on the production of nitric oxide by mouse peritoneal macrophages

C-reactive protein in concentratios of 1–20 mg/ml induces the production of nitrogen oxide by mouse peritoneal macrophages attracted by peptone solution. Protein kinases A and C and RNA and protein production inhibitors abolish this effect, while inhibitors of the lipoxigenase and cycloxigenase pathways of arachidonic acid metabolism attenuate it. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 1, pp. 48–50, January, 1998     

Necessity and sufficiency of beta interferon for nitric oxide production in mouse peritoneal macrophages.

Bacterial lipopolysaccharide and some cytokines can activate macrophages to secrete nitric oxide. Macrophage-derived nitric oxide is a key cytotoxic factor for microbicidal and tumoricidal processes. We report here that a monoclonal antibody specific for beta interferon inhibited lipopolysaccharide-induced nitric oxide production in thioglycolate-elicited C3HeB/FeJ peritoneal macrophages and macrophage-like cell line RAW 264.7. In addition, exogenous added beta interferon enabled lipopolysaccharide-hyporesponsive thioglycolate-elicited C3H/HeJ peritoneal macrophages to produce nitric oxide in response to lipopolysaccharide. These data support the concept that beta interferon provides an essential signal(s) for lipopolysaccharide-triggered nitric oxide production by mouse macrophages. Heat-killed Staphylococcus aureus, a gram-positive bacterium which was unable to initiate nitric oxide production in thioglycolate-elicited C3HeB/FeJ peritoneal macrophages in vitro, promoted nitric oxide formation in the presence of beta interferon, suggesting that beta interferon may be a general cofactor necessary for bacterium-derived stimulus-induced nitric oxide production in these macrophages. However, neither beta interferon nor tumor necrosis factor alpha, alone or in combination, triggered nitric oxide production in thioglycolate-elicited mouse peritoneal macrophages, demonstrating that these macrophage-derived cytokines, while necessary, were not sufficient by themselves for the induction of nitric oxide production in these cells. On the other hand, gamma interferon and tumor necrosis factor alpha acted together to induce nitric oxide production in vitro in the absence of lipopolysaccharide in thioglycolate-elicited mouse peritoneal macrophages, indicating that these two types of interferons provided different signals during the activation of these macrophages.     

Involvement of nitric oxide in spinally mediated hyperalgesia in the mouse.

Intrathecal injection of N-methyl-D-aspartate (NMDA) induces a short duration hyperalgesia in mice. An inhibitor of nitric oxide synthase (NOS), N omega-nitro-L-arginine methyl ester (L-NAME), administered either systemically or intrathecally, blocked the NMDA-induced hyperalgesia. This effect was partially reversed by the NOS substrate, L-arginine. Intrathecal hemoglobin mimicked the effects of L-NAME. Intrathecal injection of the NO-donating compounds, sodium nitroprusside (SNP) and hydroxylamine, resulted in a hyperalgesia that lasted 3 h and was reduced by coadministration of hemoglobin. Thus, nitric oxide production appears to mediate NMDA-induced hypersensitivity and may contribute to other forms of centrally induced hyperalgesia.     

A specific sequence of stimulation is required to induce synthesis of the antimicrobial molecule nitric oxide by mouse macrophages.

Nitric oxide production by macrophages required either simultaneous or sequential exposure to gamma interferon and lipopolysaccharide; exposure to lipopolysaccharide followed by exposure to gamma interferon gave little response. The apparently evanescent nature of the lipopolysaccharide signal, necessitating persistent stimulation, could be essential to down-regulating nitric oxide production after bacteria are cleared in vivo.     

Ethanol-induced neutrophil apoptosis is mediated through nitric oxide

Clinical reports indicate that acute ethanol intoxication in chronic ethanol abusers is associated with neutropenia. We hypothesize that ethanol accelerates the apoptosis of neutrophils thus decreasing the peripheral blood count of neutrophils. We studied the effect of ethanol on neutrophil apoptosis in vivo as well as in vitro. Human neutrophils harvested from healthy subjects after an alcohol drinking binge showed enhanced apoptosis (before, 0.5+/-0.25 vs. after, 26.1+/-2.6% apoptotic neutrophils/field). Peritoneal neutrophils isolated from ethanol-treated rats also showed increased (P < 0.0001) apoptosis when compared with neutrophils isolated from control rats (control, 0.8+/-0.2% vs. ethanol, 11.8+/-0.7% apoptotic neutrophils/field). In in vitro studies, ethanol in concentrations of 50 mM and higher accelerated the apoptosis of human and rat neutrophils. This effect of ethanol on human neutrophils was time dependent. DNA isolated from ethanol-treated human neutrophils displayed integer multiples of 180 base pairs (ladder pattern), further confirming the effect of ethanol on neutrophil apoptosis. N(G)-monomethyl-L-arginine monoacetate and N(G)-nitro-L-arginine methyl ester, inhibitors of nitric oxide (NO) synthase, attenuated the ethanol-induced neutrophil apoptosis. Sodium nitroprusside, a NO donor, also promoted neutrophil apoptosis. Moreover, ethanol enhanced neutrophil expression of inducible NO synthase. In addition, ethanol stimulated neutrophil NO generation. These results suggest that ethanol accelerates neutrophil apoptosis. This effect of ethanol on neutrophil apoptosis seems to be mediated through the generation of NO.     

Killing of Legionella pneumophila by nitric oxide in gamma-interferon-activated macrophages.

The role of nitric oxide (NO) radicals in killing the intracellular bacterial pathogen Legionella pneumophila (Lp) was examined in infected macrophages. Murine (RAW 264.7) and human (HL-60) cell monolayers were treated with 100 U/ml gamma-interferon (IFN) and cocultured with Lp in the presence and absence of NGMMA, a specific inhibitor of NO production. Viable Lp in IFN-treated RAW 264.7 cells decreased from 3.8 to 0.7 +/- 0.12 log CFU/ml after 24 h incubation, whereas in IFN+NGMMA-treated RAW 264.7 cells, viable Lp persisted at 2.2 +/- 0.2 log CFU/ml after 24 h. This increased survival corresponded with an inhibition of NO production (5.65 +/- 2.99 microM with NGMMA vs. 58.6 +/- 5.36 microM without NGMMA). Viable Lp were susceptible to killing, in a dose-dependent fashion, by 0, 2.5, and 5.0 mM sodium nitroprusside, a source of NO radicals. IFN-treated RAW 264.7 cells also had significantly decreased levels of intracellular iron (below assay limit) when compared to IFN+NGMMA-treated cells (72.0 +/- 0.78% of control). Normally permissive HL-60 cells treated with IFN were bacteriostatic rather than bactericidal, and NO production was not detected above background. Thus, NO radicals play a critical role in the bactericidal activity against Lp by IFN-treated RAW 264.7 cells, but the absence of NO production limits IFN-treated HL-60 cells to bacteriostasis.     

Entamoeba histolytica modulates the nitric oxide synthase gene and nitric oxide production by macrophages for cytotoxicity against amoebae and tumour cells.

Nitric oxide (NO) is the major cytotoxic molecule produced by activated macrophages for cytotoxicity against Entamoeba histolytica trophozoites. In the present study, we determined whether E. histolytica infection and soluble amoebic proteins affected macrophage cytotoxicity against amoebae and tumour cells by modulating the inducible NO synthase gene (iNOS) and NO (measured as nitrite, NO2-) and tumour necrosis factor-alpha (TNF-alpha) production. Amoebic liver abscess-derived macrophages [days 10, 20, 30 post-infection (p.i.)] stimulated with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) showed increased cytotoxicity against L929 cells (TNF-alpha-sensitive), but were refractory for killing amoebae and P815 cells (both NO-sensitive), concomitant with low NO2- production (< 4 microM/10(6) cells). In contrast, peritoneal and spleen macrophages at 10 and 20 days p.i. activated with IFN-gamma and LPS demonstrated increased killing of amoebae, and L929 and P815 cells concomitant with high NO2- production (> 12 microM/10(6) cells). Pretreatment of mouse bone marrow-derived macrophages with amoebic proteins suppressed IFN-gamma and LPS-induced amoebicidal (33%) and tumoricidal (44-49%) activities, with a corresponding decrease in TNF-alpha (56%) and NO (41%) production as well as TNF-alpha (41%) and iNOS (27%) mRNA by Northern blot analyses as compared to untreated activated controls. Inhibition of prostaglandin E2 (PGE2) biosynthesis in abscess and naive macrophages pretreated with amoebic proteins augmented IFN-gamma- and LPS-induced killing of L929 cells and TNF-alpha production, but failed to increase killing of P815 cells and amoebae as well as iNOS mRNA levels or NO production. These results suggest that E. histolytica selectively induces dysfunction of macrophage cytotoxicity by modulating iNOS mRNA expression and NO production independent from TNF-alpha and PGE2 allowing the parasites to survive within the host by impairing host immune responses.     

T-Cell hyporesponsiveness induced by activated macrophages through nitric oxide production in mice infected with Mycobacterium tuberculosis.

In active tuberculosis, T-cell response to Mycobacterium tuberculosis is known to be reduced. In the course of Mycobacterium tuberculosis infection in mice, we observed that T-cell proliferation in response to M. tuberculosis purified protein derivative (PPD) reached the maximum level on day 7, then declined to the minimal level on day 14, and persisted at a low level through day 28 postinfection. The frequency of PPD-specific CD4 T cells in the spleen on day 28 decreased to one-sixth on day 7. To further investigate the mechanism of this T-cell hyporesponsiveness, we next analyzed the suppressive activity of spleen macrophages on T-cell function. The nonspecific proliferative response of naive T cells and the PPD-specific proliferative response of T cells were suppressed by day 28 macrophages, but not by day 7 macrophages or naive macrophages. This reduction of proliferative response was restored by addition of nitric oxide synthesis inhibitor, NG-monoethyl-L-arginine monoacetate, but not by monoclonal antibody against interleukin 10 or transforming growth factor beta. These data indicate that the macrophages from mice chronically infected with M. tuberculosis suppress T-cell response through production of nitric oxide, suggesting that nitric oxide-induced elimination mediated by activated macrophages may reduce the T-cell response and the number of mycobacterium-specific CD4 T cells in vivo.     

Quercetin inhibits LPS-induced nitric oxide and tumor necrosis factor-alpha production in murine macrophages.

High amounts of nitric oxide and TNF-alpha generated by activated macrophages induce several pathophysiological conditions during acute and chronic inflammation. Identification of new pharmacological reagents that can prevent TNF-alpha and/or NO overproduction is of considerable medical interest. In this report we provide evidence that the overproduction of TNF-alpha and NO by LPS stimulated macrophages can be markedly inhibited by quercetin, a major active component of plant Rhododendron cinnabarium.     

Aggregates of denatured proteins stimulate nitric oxide and superoxide production in macrophages

Objective  

Denatured proteins are deposited in damaged tissues, around implanted biomaterials, during natural aging as well as in a heterogeneous group of amyloid diseases, such as Alzheimer’s disease. There is evidence that tissue damage observed in amyloidosis is mediated mainly by factors released from activated macrophages, such as superoxide and nitric oxide (NO), as opposed to direct interaction between amyloid fibrils and nonimmune cells.     

Mitochondrial control of inducible nitric oxide production in stimulated RAW 264.7 macrophages

Addition of glucose to activated RAW 264.7 macrophages or addition of mitochondrial electron-transfer chain inhibitors enhanced the cellular nitric oxide production. An additive effect of rotenone or antimycin A and glucose on enhancing nitric oxide production was shown. Uncoupling the mitochondria by a chemical uncoupler decreased nitric oxide production. The mitochondria membrane potential was found to be important for cell viability. Although nitric oxide is the physiological inhibitor of mitochondrial respiration, this study indicates that mitochondria were not inhibited in the activated macrophages. Furthermore, a role of mitochondria in the rapid regulation of nitric oxide synthesis by the inducible nitric oxide synthase has been demonstrated.     

Differential regulation of cytokine production by nitric oxide.

Nitric oxide (NO) has recently been identified as a potent and pleiotropic intracellular mediator produced by and acting on many cells of the body. Although considerable attention has been devoted to the regulation of NO by inflammatory cytokines, and also to the role of NO as an important effector molecule in immune function, there is very little information on the role of this mediator in modulating T-cell-dependent cytokine production. In this study we show that physiological levels of NO (either produced by activated macrophages or by the addition of exogenous NO donors) can selectively down-regulate interleukin-3 (IL-3) production by spleen cells from contact-sensitized mice, while leaving IL-2 activity unaffected. Thus NO may have an important role as an immunomodulatory as well as effector molecule in the immune system.     

Inhibitory effect of cyclosporin A and FK506 on nitric oxide production by cultured macrophages. Evidence of a direct effect on nitric oxide synthase activity.

Casein-elicited peritoneal macrophages from mice were cultured either alone or with interferon-gamma (IFN-gamma) and bacterial lipopolysaccharide (LPS), and the effect of cyclosporin A (CsA) and FK506 on NO2- production (due technical difficulties NO2- was taken as the index for NO) was analysed. We observed an inhibitory effect of CsA and FK506 on NO2- production. The IC50 for NO2- production by casein-elicited macrophages was 0.1 microgram/ml for CsA and 0.3 microgram/ml FK506. The effect of both drugs was dose-dependent and was more clear in non-stimulated macrophages. The presence of IFN-gamma and LPS in the culture increased NO2- production by casein-elicited macrophages and partially eliminated the inhibition exerted by CsA and FK506. Both drugs acted directly on the nitric oxide synthase (NOS), since CsA and FK506 reduced by 35% and by 17%, respectively, NOS activity in the crude cytosolic fraction. However, CsA and FK506 did not alter 14CO2 production from [1-14C]glucose, suggesting that the pentose monophosphate pathway activity was not modified. These data add new insight into the interpretation of the immunosuppressive properties of both drugs.     

Coccidioides releases a soluble factor that suppresses nitric oxide production by murine primary macrophages

We studied the effect of the presence of Coccidioides on the production of nitric oxide (NO) by primary macrophages previously activated by IFN-γ and LPS. The fungal cells were isolated from cultures of arthroconidia that had been incubated for 24 h in a medium that supported parasitic phase growth and were co-cultured with the macrophages. These live, first-generation parasitic cells of Coccidioides, referred to as spherule initials, suppressed NO production as well as iNOS mRNA expression by activated macrophages. Phagocytosis was not required for suppression of NO. We also showed that the culture supernatant of the spherule initials was capable of suppressing NO production, and that this activity was mediated by an as yet unidentified, secreted fungal factor(s). Heat-, paraformaldehyde- or X-ray-treated spherule initials did not show this inhibitory effect. To our surprise, macrophages obtained from iNOS-deficient mice revealed phagocytic activity and killing efficiency which were comparable to that of macrophages isolated from wild type C57BL/6 mice. Although the cultured fungal pathogen can suppress NO production, this oxidative product is apparently not essential for in vitro killing of Coccidioides by activated macrophages. Our results suggest that other unidentified fungicidal mechanisms exist against Coccidioides which are apparently independent of NO production.     

Requirements for nitric oxide production by turbot (Scophthalmus maximus) head kidney macrophages

The effect of different cytokines and bacterial lipopolysaccharide (LPS) on turbot (Scophthalmus maximus) macrophage nitric oxide (NO) production has been studied. We have found two different responses concerning NO production in response to LPS. We have studied 43 turbot and only macrophage cultures derived from 30.2% of these turbot were significantly stimulated by LPS. The macrophage populations that did not respond to LPS, showed a constitutive production that was significantly reversed by NO inhibitors like N(G)-methyl-L-arginine (L-NMMA) and N-omega-nitro-L-arginine (L-NAME), and was dependent on intracellular calcium concentration. We studied the effect of other stimuli combined with LPS on the NO production of these otherwise non-responsive macrophages. LPS combined with turbot macrophage activating factor (MAF) containing supernatants, was capable of significantly stimulating some of these macrophage populations. The same response was observed when LPS was combined with turbot IFN-alphabeta-like substances. When LPS was combined with human recombinant tumor necrosis factor alpha (hrTNF-alpha), the NO production was significantly induced in all macrophage populations studied.     

白芍总苷对巨噬细胞一氧化氮和诱导型一氧化氮合酶生成的影响及其机制研究

目的：探讨白芍总苷（TGP）抗炎作用与调节巨噬细胞一氧化氮（NO）的产生及诱导型一氧化氮合酶（iNOS）的表达的关系,并从调控核转录因子-κB（NF-κB）活性的途径探讨其作用机制。方法：预先用不同浓度的TGP与大鼠腹腔巨噬细胞共同孵育,然后加入脂多糖（LPS）刺激细胞,检测细胞培养液中NO的产生,Westernblot方法检测iNOS的表达和NF-κB抑制蛋白α（IκBα）的含量,同时检测NF-κB与DNA的结合活性。结果：TGP显著抑制了LPS诱导的大鼠腹腔巨噬细胞产生NO、表达i-NOS,同时也显著增加了细胞内IκBα蛋白的含量和抑制了NF-κB与DNA的结合活性。结论：TGP的抗炎作用与其通过抑制巨噬细胞NF-κB的活性,从而降低巨噬细胞iNOS的表达、减少NO产生密切相关。