Platelet-Activating Factor Induces Nitric Oxide Synthesis in Trypanosoma cruzi-Infected Macrophages and Mediates Resistance to Parasite Infection in Mice

ABSTRACT Trypanosoma cruzi replicates in nucleated cells and is susceptible to being killed by gamma interferon-activated macrophages through a mechanism dependent upon NO biosynthesis. In the present study, the role of platelet-activating factor (PAF) in the induction of NO synthesis and in the activation of the trypanocidal activity of macrophages was investigated. In vitro, PAF induced NO secretion byT. cruzi-infected macrophages and the secreted NO inhibited intracellular parasite growth. The addition of a PAF antagonist, WEB 2170, inhibited both NO biosynthesis and trypanocidal activity. The inducible NO synthase/l-arginine pathway mediated trypanocidal activity, since it was inhibited by treatment withl-N-monomethyl arginine (l-NMMA), an l-arginine analog. PAF-mediated NO production in infected macrophages appears to be dependent on tumor necrosis alpha (TNF-α) production, since the addition of a neutralizing anti-TNF-α monoclonal antibody mAb inhibited NO synthesis. To test the role of PAF in mediating resistance or susceptibility to T. cruziinfection, infected mice were treated with WEB 2170, a PAF antagonist. These animals had higher parasitemia and earlier mortality than did vehicle-treated mice. Taken together, our results suggest that PAF belongs to a group of mediators that coordinate the mechanisms of resistance to infections with intracellular parasites.

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Role of NO and PAF in the impairment of skeletal muscle contractility induced by TNF-α

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2000.279.6.r2156 ◽

2000 ◽

Vol 279 (6) ◽

pp. R2156-R2163 ◽

Cited By ~ 28

Author(s):

Giuseppe Alloatti ◽

Claudia Penna ◽

Filippo Mariano ◽

Giovanni Camussi

Keyword(s):

Skeletal Muscle ◽

Methyl Ester ◽

Platelet Activating Factor ◽

Inhibitory Effect ◽

No Production ◽

Force Frequency ◽

Muscle Contractility ◽

Tnf Α ◽

Frequency Relationship

The role of platelet-activating factor (PAF) and nitric oxide (NO) as mediators of the effects of tumor necrosis factor-α (TNF-α) on skeletal muscle contractility was studied in guinea pig extensor digitorum longus (EDL) muscle. TNF-α (5–10 ng/ml) reduced contractility at every stimulation frequency (1–200 Hz) and shifted the force-frequency relationship to the right. The role of NO and PAF as mediators of TNF-α was suggested by the protective effect of N G-nitro-l-arginine methyl ester (l-NAME; 1 mM), but not of N G-nitro-d-arginine methyl ester (d-NAME; 1 mM), and by the inhibitory effect of the PAF-receptor antagonist WEB-2170 (3 μM). TNF-α increased the production of PAF and NO. Similar to TNF-α, both S-nitroso- N-acetylpenicillamine (0.5–1 μM), an NO-generating compound, and PAF (10–20 nM) reduced EDL contractility. l-NAME, but not d-NAME, blocked the negative effect of PAF. Blockade of phospholipase A2, which is required for PAF synthesis, significantly reduced the effects of TNF-α. WEB-2170 inhibited NO synthesis induced by TNF-α and PAF-stimulated NO production. These results suggest that both PAF and NO contribute to the development of the mechanical alterations induced by TNF-α and that NO production is downstream to the synthesis of PAF.

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Trypanosoma cruzi: in vitro induction of macrophage microbicidal activity.

Journal of Experimental Medicine ◽

10.1084/jem.148.1.288 ◽

1978 ◽

Vol 148 (1) ◽

pp. 288-300 ◽

Cited By ~ 94

Author(s):

N Nogueira ◽

Z A Cohn

Keyword(s):

Trypanosoma Cruzi ◽

Spleen Cell ◽

Peritoneal Macrophages ◽

Complete Disappearance ◽

Microbicidal Activity ◽

Trypanocidal Activity ◽

Intracellular Parasites ◽

Normal Spleen

Normal, resident and inflammatory mouse peritoneal macrophages can be induced to display microbicidal activity against trypomastigotes of Trypanosoma cruzi by exposure to products from antigen-pulsed, sensitized spleen cell populations. Optimal macrophage microbicidal activity was achieved by constant exposure and daily renewal of the spleen cell factors. Macrophages obtained after an intraperitoneal injection of mild inflammatory agents were rapidly induced, displaying trypanocidal activity 24 h after exposure to the active spleen cell factor(s), and by 48 h, parasites were no longer observed. Resident peritoneal macrophages required 24 h longer for activation. Removal of the factor(s) before achieving complete disappearance of intracellular parasites led to resumed growth of the surviving organisms. The spleen cell factor(s) is effective when added either before or after exposure of the macrophages to trypomastigotes, and does not itself alter parasite viability. Dilution of the factor(s) up to 1:16 still results in significant trypanocidal activity. In vivo activated cells, obtained after a specific secondary challenge of animals infected with T. cruzi or Bacille Calmette-Guérin, lose their trypanocidal activity under in vitro conditions. This loss of activity can be prevented or restored by the addition of the active spleen cell factor(s). Induction of trypanocidal activity is also obtained with products from Concanavalin A- or lipopolysaccharide-stimulated normal spleen cells.

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Leukotriene B4 Induces Nitric Oxide Synthesis in Trypanosoma cruzi-Infected Murine Macrophages and Mediates Resistance to Infection

Infection and Immunity ◽

10.1128/iai.70.8.4247-4253.2002 ◽

2002 ◽

Vol 70 (8) ◽

pp. 4247-4253 ◽

Cited By ~ 55

Author(s):

A. Talvani ◽

F. S. Machado ◽

G. C. Santana ◽

A. Klein ◽

L. Barcelos ◽

...

Keyword(s):

Nitric Oxide ◽

Trypanosoma Cruzi ◽

Leukotriene B4 ◽

No Production ◽

Dependent Manner ◽

Necrosis Factor Alpha ◽

Tnf Α ◽

Ifn Γ

ABSTRACT The production of nitric oxide (NO) by gamma interferon (IFN-γ)-activated macrophages is a major effector mechanism during experimental Trypanosoma cruzi infection. In addition to IFN-γ, chemoattractant molecules, such as platelet-activating factor (PAF) and CC chemokines, may also activate macrophages to induce NO and mediate the killing of T. cruzi in an NO-dependent manner. Here we investigated the ability of leukotriene B4 (LTB4) to induce the production of NO by macrophages infected with T. cruzi in vitro and whether NO mediated LTB4-induced parasite killing. The activation of T. cruzi-infected but not naive murine peritoneal macrophages with LTB4 induced the time- and concentration-dependent production of NO. In addition, low concentrations of LTB4 acted in synergy with IFN-γ to induce NO production. The NO produced mediated LTB4-induced microbicidal activity in macrophages, as demonstrated by the inhibitory effects of an inducible NO synthase inhibitor. LTB4-induced NO production and parasite killing were LTB4 receptor dependent and were partially blocked by a PAF receptor antagonist. LTB4 also induced significant tumor necrosis factor alpha (TNF-α) production, and blockade of TNF-α suppressed LTB4-induced NO release and parasite killing. A blockade of LTB4 or PAF receptors partially inhibited IFN-γ-induced NO and TNF-α production but not parasite killing. Finally, daily treatment of infected mice with CP-105,696 was accompanied by a significantly higher level of blood parasitemia, but not lethality, than that seen in vehicle-treated animals. In conclusion, our results suggest a role for LTB4 during experimental T. cruzi infection. Chemoattractant molecules such as LTB4 not only may play a major role in leukocyte migration into sites of inflammation in vivo but also, in the event of an infection, may play a relevant role in the activation of recruited leukocytes to kill the invading microorganism in an NO-dependent manner.

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Absence of Bim sensitizes mice to experimental Trypanosoma cruzi infection

Cell Death and Disease ◽

10.1038/s41419-021-03964-6 ◽

2021 ◽

Vol 12 (7) ◽

Author(s):

Marcela Hernández-Torres ◽

Rogério Silva do Nascimento ◽

Monica Cardozo Rebouças ◽

Alexandra Cassado ◽

Kely Catarine Matteucci ◽

...

Keyword(s):

T Cells ◽

Trypanosoma Cruzi ◽

Chagas Disease ◽

Parasite Load ◽

Peritoneal Macrophages ◽

T Cell Response ◽

No Production ◽

Similar Reduction ◽

Ifn Γ

AbstractChagas disease is a life-threatening disorder caused by the protozoan parasite Trypanosoma cruzi. Parasite-specific antibodies, CD8+ T cells, as well as IFN-γ and nitric oxide (NO) are key elements of the adaptive and innate immunity against the extracellular and intracellular forms of the parasite. Bim is a potent pro-apoptotic member of the Bcl-2 family implicated in different aspects of the immune regulation, such as negative selection of self-reactive thymocytes and elimination of antigen-specific T cells at the end of an immune response. Interestingly, the role of Bim during infections remains largely unidentified. To explore the role of Bim in Chagas disease, we infected WT, Bim+/−, Bim−/− mice with trypomastigotes forms of the Y strain of T. cruzi. Strikingly, our data revealed that Bim−/− mice exhibit a delay in the development of parasitemia followed by a deficiency in the control of parasite load in the bloodstream and a decreased survival compared to WT and Bim+/− mice. At the peak of parasitemia, peritoneal macrophages of Bim−/− mice exhibit decreased NO production, which correlated with a decrease in the pro-inflammatory Small Peritoneal Macrophage (SPM) subset. A similar reduction in NO secretion, as well as in the pro-inflammatory cytokines IFN-γ and IL-6, was also observed in Bim−/− splenocytes. Moreover, an impaired anti-T. cruzi CD8+ T-cell response was found in Bim−/− mice at this time point. Taken together, our results suggest that these alterations may contribute to the establishment of a delayed yet enlarged parasitic load observed at day 9 after infection of Bim−/− mice and place Bim as an important protein in the control of T. cruzi infections.

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Identification of a microRNA signature in renal fibrosis: role of miR-21

AJP Renal Physiology ◽

10.1152/ajprenal.00273.2011 ◽

2011 ◽

Vol 301 (4) ◽

pp. F793-F801 ◽

Cited By ~ 169

Author(s):

Abolfazl Zarjou ◽

Shanzhong Yang ◽

Edward Abraham ◽

Anupam Agarwal ◽

Gang Liu

Keyword(s):

Epithelial Cells ◽

Renal Fibrosis ◽

Transforming Growth Factor ◽

Response To Treatment ◽

Tubular Epithelial Cells ◽

Altered Expression ◽

Tnf Α ◽

Tgf Β1

Renal fibrosis is a final stage of many forms of kidney disease and leads to impairment of kidney function. The molecular pathogenesis of renal fibrosis is currently not well-understood. microRNAs (miRNAs) are important players in initiation and progression of many pathologic processes including diabetes, cancer, and cardiovascular disease. However, the role of miRNAs in kidney injury and repair is not well-characterized. In the present study, we found a unique miRNA signature associated with unilateral ureteral obstruction (UUO)-induced renal fibrosis. We found altered expression in UUO kidneys of miRNAs that have been shown to be responsive to stimulation by transforming growth factor (TGF)-β1 or TNF-α. Among these miRNAs, miR-21 demonstrated the greatest increase in UUO kidneys. The enhanced expression of miR-21 was located mainly in distal tubular epithelial cells. miR-21 expression was upregulated in response to treatment with TGF-β1 or TNF-α in human renal tubular epithelial cells in vitro. Furthermore, we found that blocking miR-21 in vivo attenuated UUO-induced renal fibrosis, presumably through diminishing the expression of profibrotic proteins and reducing infiltration of inflammatory macrophages in UUO kidneys. Our data suggest that targeting specific miRNAs could be a novel therapeutic approach to treat renal fibrosis.

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Losartan Increases No Production from the Bovine Aortic Wall That is Stimulated by Angiotensin II

European Journal of Inflammation ◽

10.1177/1721727x0300100304 ◽

2003 ◽

Vol 1 (3) ◽

pp. 113-117 ◽

Cited By ~ 1

Author(s):

M. Myronidou ◽

B. Kokkas ◽

A. Kouyoumtzis ◽

N. Gregoriadis ◽

A. Lourbopoulos ◽

...

Keyword(s):

Nitric Oxide ◽

Angiotensin Ii ◽

Aortic Wall ◽

Vascular Wall ◽

Protective Role ◽

Normal Function ◽

No Production ◽

Chemical Inactivation

In these studies we investigated if losartan, an AT1- receptor blocker has any beneficial effect on NO production from the bovine aortic preparations in vitro while under stimulation from angiotensin II. Experiments were performed on intact specimens of bovine thoracic aorta, incubated in Dulbeco's MOD medium in a metabolic shaker for 24 hours under 95 % O2 and 5 % CO2 at a temperature of 37°C. We found that angiotensin II 1nM−10 μM does not exert any statistically significant action on NO production. On the contrary, angiotensin II 10nM increases the production of NO by 58.14 % (from 12.16 + 2.9 μm/l to 19.23 + 4.2 μm/l in the presence of losartan 1nM (P<0.05). Nitric oxide levels depend on both rate production and rate catabolism or chemical inactivation. Such an equilibrium is vital for the normal function of many systems including the cardiovascular one. The above results demonstrate that the blockade of AT1-receptors favors the biosynthesis of NO and indicate the protective role of losartan on the vascular wall.

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Proinflammatory responses in SARS-CoV-2 infected and soluble spike glycoprotein S1 subunit activated human macrophages

10.1101/2021.06.14.448426 ◽

2021 ◽

Author(s):

Kim Chiok ◽

Kevin Hutchison ◽

Lindsay Grace Miller ◽

Santanu Bose ◽

Tanya A Miura

Keyword(s):

Virus Infection ◽

Inflammatory Response ◽

Virus Replication ◽

Inflammatory Mediators ◽

Inflammatory Responses ◽

Activated Macrophages ◽

Human Macrophages ◽

Tnf Α ◽

Proinflammatory Responses

Critically ill COVID-19 patients infected with SARS-CoV-2 display signs of generalized hyperinflammation. Macrophages trigger inflammation to eliminate pathogens and repair tissue, but this process can also lead to hyperinflammation and resulting exaggerated disease. The role of macrophages in dysregulated inflammation during SARS-CoV-2 infection is poorly understood. We used SARS-CoV-2 infected and glycosylated soluble SARS-CoV-2 Spike S1 subunit (S1) treated THP-1 human-derived macrophage-like cell line to clarify the role of macrophages in pro-inflammatory responses. Soluble S1 upregulated TNF-α and CXCL10 mRNAs, and induced secretion of TNF-α from THP-1 macrophages. While THP-1 macrophages did not support productive SARS-CoV-2 replication, virus infection resulted in upregulation of both TNF-α and CXCL10 genes. Our study shows that S1 is a key viral component inducing inflammatory response in macrophages, independently of virus replication. Thus, virus-infected or soluble S1-activated macrophages may become sources of pro-inflammatory mediators contributing to hyperinflammation in COVID-19 patients.

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MiR-22-3p suppresses sepsis-induced acute kidney injury by targeting PTEN

Bioscience Reports ◽

10.1042/bsr20200527 ◽

2020 ◽

Vol 40 (6) ◽

Author(s):

Xudong Wang ◽

Yali Wang ◽

Mingjian Kong ◽

Jianping Yang

Keyword(s):

Acute Kidney Injury ◽

Inflammatory Response ◽

Periodic Acid ◽

Kidney Injury ◽

Luciferase Reporter ◽

Tunel Staining ◽

Tnf Α

Abstract Background: Septic acute kidney injury is considered as a severe and frequent complication that occurs during sepsis. The present study was performed to understand the role of miR-22-3p and its underlying mechanism in sepsis-induced acute kidney injury. Methods: Rats were injected with adenovirus carrying miR-22-3p or miR-NC in the caudal vein before cecal ligation. Meanwhile, HK-2 cells were transfected with the above adenovirus following LPS stimulation. We measured the markers of renal injury (blood urea nitrogen (BUN), serum creatinine (SCR)). Histological changes in kidney tissues were examined by hematoxylin and eosin (H&E), Masson staining, periodic acid Schiff staining and TUNEL staining. The levels of IL-1β, IL-6, TNF-α and NO were determined by ELISA assay. Using TargetScan prediction and luciferase reporter assay, we predicted and validated the association between PTEN and miR-22-3p. Results: Our data showed that miR-22-3p was significantly down-regulated in a rat model of sepsis-induced acute kidney injury, in vivo and LPS-induced sepsis model in HK-2 cells, in vitro. Overexpression of miR-22-3p remarkably suppressed the inflammatory response and apoptosis via down-regulating HMGB1, p-p65, TLR4 and pro-inflammatory factors (IL-1β, IL-6, TNF-α and NO), both in vivo and in vitro. Moreover, PTEN was identified as a target of miR-22-3p. Furthermore, PTEN knockdown augmented, while overexpression reversed the suppressive role of miR-22-3p in LPS-induced inflammatory response. Conclusions: Our results showed that miR-22-3p induced protective role in sepsis-induced acute kidney injury may rely on the repression of PTEN.

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Biological and Inflammatory Effects of Antigen 5 from Polybia paulista (Hymenoptera, Vespidae) Venom in Mouse Intraperitoneal Macrophages

Toxins ◽

10.3390/toxins13120850 ◽

2021 ◽

Vol 13 (12) ◽

pp. 850

Author(s):

Murilo Luiz Bazon ◽

Luis Gustavo Romani Fernandes ◽

Isabela Oliveira Sandrini Assugeni ◽

Lucas Machado Pinto ◽

Patrícia Ucelli Simioni ◽

...

Keyword(s):

Peritoneal Macrophages ◽

In Vivo Studies ◽

M2 Macrophage ◽

No Production ◽

Activated Macrophages ◽

In Vitro Production ◽

Polybia Paulista ◽

Antigen 5

The social wasp Polybia paulista (Hymenoptera, Vespidae) is highly aggressive, being responsible for many medical occurrences. One of the most allergenic components of this venom is Antigen 5 (Poly p 5). The possible modulation of the in vitro immune response induced by antigen 5 from P. paulista venom, expressed recombinantly (rPoly p 5), on BALB/c mice peritoneal macrophages, activated or not with LPS, was assessed. Here, we analyzed cell viability changes, expression of the phosphorylated form of p65 NF-κB subunit, nitric oxide (NO), proinflammatory cytokines production, and co-stimulatory molecules (CD80, CD86). The results suggest that rPoly p 5 does not affect NO production nor the expression of co-stimulatory molecules in mouse peritoneal macrophages. On the other hand, rPoly p 5 induced an increase in IL-1β production in non-activated macrophages and a reduction in the production of TNF-α and MCP-1 cytokines in activated macrophages. rPoly p 5 decreased the in vitro production of the phosphorylated p65 NF-κB subunit in non-activated macrophages. These findings suggest an essential role of this allergen in the polarization of functional M2 macrophage phenotypes, when analyzed in previously activated macrophages. Further investigations, mainly in in vivo studies, should be conducted to elucidate Polybia paulista Ag5 biological role in the macrophage functional profile modulation.

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Immunomodulation by 17β-estradiol in bivalve hemocytes

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00139.2006 ◽

2006 ◽

Vol 291 (3) ◽

pp. R664-R673 ◽

Cited By ~ 38

Author(s):

Laura Canesi ◽

Caterina Ciacci ◽

Lucia Cecilia Lorusso ◽

Michele Betti ◽

Tiziana Guarnieri ◽

...

Keyword(s):

Kinase Inhibitors ◽

Hydrolytic Enzymes ◽

Physiological Role ◽

Estrogen Receptor Α ◽

Nitrite Accumulation ◽

No Production ◽

17Β Estradiol

In mammals, estrogens have dose- and cell-type-specific effects on immune cells and may act as pro- and anti-inflammatory stimuli, depending on the setting. In the bivalve mollusc Mytilus, the natural estrogen 17β-estradiol (E2) has been shown to affect neuroimmune functions. We have investigated the immunomodulatory role of E2 in Mytilus hemocytes, the cells responsible for the innate immune response. E2 at 5–25 nM rapidly stimulated phagocytosis and oxyradical production in vitro; higher concentrations of E2 inhibited phagocytosis. E2-induced oxidative burst was prevented by the nitric oxide (NO) synthase inhibitor NG-monomethyl-l-arginine and superoxide dismutase, indicating involvement of NO and O2−; NO production was confirmed by nitrite accumulation. The effects of E2 were prevented by the antiestrogen tamoxifen and by specific kinase inhibitors, indicating a receptor-mediated mechanism and involvement of p38 MAPK and PKC. E2 induced rapid and transient increases in the phosphorylation state of PKC, as well as of a aCREB-like (cAMP responsive element binding protein) transcription factor, as indicated by Western blot analysis with specific anti-phospho-antibodies. Localization of estrogen receptor-α- and -β-like proteins in hemocytes was investigated by immunofluorescence confocal microscopy. The effects of E2 on immune function were also investigated in vivo at 6 and 24 h in hemocytes of E2-injected mussels. E2 significantly affected hemocyte lysosomal membrane stability, phagocytosis, and extracellular release of hydrolytic enzymes: lower concentrations of E2 resulted in immunostimulation, and higher concentrations were inhibitory. Our data indicate that the physiological role of E2 in immunomodulation is conserved from invertebrates to mammals.

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