Search

The macrophage displays functional and phenotypic diversity, which appears, in no small part, to stem from the ability of macrophages to adapt functionally to changes in their tissue microenvironment. Here, we describe the differential activity of peritoneal macrophages with or without the presence of thioglycollate (TG), an inflammatory drug that encouraged the recruitment of macrophages, during aging. The peritoneal- resident macrophages dramatically reduced in phagocytosis and pro-inflammatory cytokines secretion with aging, whereas the functions of macrophages recruited by TG were not significantly changed with aging. These results suggest that macrophages may be changed by their environment in advanced age, and could provide possible explanations for the controversial results regarding differential changes in macrophages in other papers. [ABSTRACT FROM AUTHOR]

Context: Several studies have shown that heparin is able to inhibit leukocyte recruitment during an early acute inflammatory response. However, considering the pharmacokinetic aspects of heparin and the dynamics of inflammation our objective was to determine if heparin is able to retain its antimigratory property during a prolonged inflammatory response. Objective: Compare the effect of heparin on leukocyte recruitment to the peritoneal cavity during early acute inflammatory response and for a longer time post-inflammatory stimulus. Materials and methods: Wistar rats pre-treated with subcutaneous heparin in doses of 1, 5, and 15 µg/kg were challenged with 2 mL intraperitoneal thioglycollate. After 3 or 8 h, the animals were killed. The cells in the peritoneal cavity were collected and counted. For differential counting, cells from peritoneal lavage and from blood were distended over a glass slide, stained, and counted. Results: After 3 h, heparin inhibited cell influx to the injury site at all tested dosages. The largest effect was achieved at a 5 µg/kg dose (83% of reduction, p < 0.001). After 8 h, heparin at a 1 µg/kg dose reduced 63% of cellular infiltration ( p < 0.001); the group treated with a 15 µg/kg dose presented an pro-inflammatory effect observed by the higher proportions, when compared with the thioglycollate group, of neutrophils on whole blood (60.9%, p < 0.001) and peritoneal fluid (27.3%, p < 0.05), and whole blood monocytes (117.8%, p < 0.01). Conclusion: These findings show that the heparin effect on leukocyte recruitment varies depending on its dosage and the duration of the inflammation. [ABSTRACT FROM AUTHOR]

Targeted disruption of the Alox15 gene makes mice resistant to angiotensin II-, DOCA/salt-, and Nω-nitro-L-arginine methyl ester (L-NAME)-induced experimental hypertension. Macrophages, a primary source of Alox15, are facilitating this resistance, but the underlying mechanism is not known. Because Alox15 metabolites are peroxisome proliferator-activated receptor (PPAR)Υ agonists, we hypothesized that activation of macrophage PPARΥ is the key step in Alox15 mediation of hypertension. Thioglycollate, used for macrophage elicitation, selectively upregulated PPARΥ and its target gene CD36 in peritoneal macrophages of both wild-type (WT) and Alox15-/- mice. Moreover, thioglycollate-injected Alox15 mice became hypertensive upon L-NAME treatment. A similar hypertensive effect was observed with adoptive transfer of thioglycollate-elicited Alox15-/- macrophages into Alox15-/- recipient mice. The role of PPAR was further specified by using the selective PPARΥ antagonist GW9662.WT mice treated with 50 µ/kg daily dose of GW9662 for 12 days became resistant to L-NAME-induced hypertension. The PPARΥ antagonist treatment also prevented L-NAME-induced hypertension in thioglycollate-injected Alox15-/- mice, indicating a PPARΥ-mediated effect in macrophage elicitation and the resultant hypertension. These results indicate a regulatory role for macrophage-localized PPARΥ in L-NAME-induced experimental hypertension. [ABSTRACT FROM AUTHOR]

Abstract: Suppression of interleukin (IL)-6 production has beneficial effects against various inflammatory diseases. Through a rapid screening system, we found that nitazoxanide, or 2-acetyloxy-N-(5-nitro-2-thiazolyl) benzamide, which is a well-known antiparasitic agent, suppressed lipopolysaccharide (LPS)-induced production of IL-6 from RAW 264.7 cells and mouse peritoneal macrophages, with 50% inhibitory concentrations (IC50s) of 1.54mM and 0.17mM, respectively. Nitazoxanide also inhibited the LPS-induced expression of IL-6 mRNA in RAW 264.7 cells. To investigate the effects of nitazoxanide in vivo, we orally administered nitazoxanide at a dose of 100mg/kg to mice 2h before a 1-mL intraperitoneal injection of 4% thioglycollate (TG). Six hours after TG injection, plasma IL-6 levels were markedly lower (by 90%) than the levels in vehicle-treated mice. These data suggest that nitazoxanide could be a promising lead compound for agents against various diseases associated with overproduction of IL-6. [Copyright &y& Elsevier]

Objective: The aim of this study was to investigate effects of CD137 ligand (CD137L)-mediated reverse signaling on cellular responses in thioglycollate-elicited mouse peritoneal macrophages. Methods: Five-week-old male C57B6 mice were injected intraperitoneally with thioglycollate for 3 days to isolate peritoneal macrophages. We counted total cell numbers with a Cell Lab Quanta SC. CD137L expression was examined with a flow cytometer. We also measured expression of inflammatory cytokines by flow cytometry and/or real time-PCR. Results: Cross-linking of CD137L with recombinant CD137-Fc protein (rCD137-Fc) increased total numbers of thioglycollate-elicited mouse peritoneal macrophages (hIgG-Fc- vs. rCD137-Fc-treated group, p < 0.05). However, ligation reduced the increase in IL-1β and IL-6 levels. Real-time PCR analysis showed that treatment of cells with rCD137-Fc also reduced transcript levels of IL-1β, IL-6, iNOS and COX2 (hIgG-Fc- vs. rCD137-Fc-treated group, p < 0.05), as well as expression of CD137L. Conclusion: Reverse signals initiated by CD137L negatively modulate certain immune functions of thioglycollate-elicited peritoneal macrophages. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Metastatic breast cancer is an important contributor to morbidity and mortality. Hence, new therapies are needed that target breast cancer metastases. Here, we focus on Mage-b as a possible vaccine target to prevent the development of breast cancer metastases, through activation of Mage-b-specific cytotoxic T lymphocytes (CTL). The syngeneic cell line 4T1, highly expressing Mage-b, was used as a pre-clinical metastatic mouse breast tumor model. BALB/c mice received three preventive intraperitoneal immunizations with Mage-b DNA vaccine mixed with plasmid DNA, secreting granulocyte–macrophage colony stimulating factor (GM-CSF). In addition, antigen-presenting cells were more efficiently recruited to the peritoneal cavity by the injection of thioglycollate broth (TGB), prior to each immunization. Immunization with Mage-b/GM-CSF/TGB significantly reduced the number of metastases by 67% compared to the saline/GM-CSF/TGB and by 69% compared to the vector control/GM-CSF/TGB. Also, tumor growth was significantly reduced by 45% in mice vaccinated with Mage-b/GM-CSF/TGB compared to the saline/GM-CSF/TGB and by 47% compared to the control vector/GM-CSF/TGB group. In vivo, the number of CD8 T cells significantly increased in the primary tumors and metastases of mice vaccinated with Mage-b/GM-CSF/TGB compared to the saline/GM-CSF/TGB and the control vector/GM-CSF/TGB group, while the number of CD4 T cells significantly decreased. The combination of Mage-b, GM-CSF and TGB did not only induce significantly higher levels of IFNγ in the lymph nodes of vaccinated compared to control mice, but also induced significantly higher expression levels of Fas-ligand (FasL) in the primary tumors (expressing Fas protein constitutively), compared to the control mice. Whether the interaction between Fas and FasL may have contributed to the smaller tumors needs to be further analyzed. [ABSTRACT FROM AUTHOR]

Leukocyte apoptosis is an energy-dependent process that facilitates resolution of the cellular inflammatory response. Levels of apoptosis can be accelerated or inhibited after exposure to various stimuli. To compare apoptosis in transmigrated leukocytes, two models of peritonitis in mice were used that both cause leukocyte influx into the peritoneal cavity: (1) intraperitoneal thioglycollate administration producing a sterile peritonitis and (2) cecal ligation and puncture (CLP) producing a polymicrobial bacterial peritonitis. Samples of blood and peritoneal exudate cells (PEC) were collected at multiple time points after induction of peritonitis. Leukocytes were either fixed immediately to determine an immediate apoptosis level or cultured for 24 h to determine a delayed apo- ptosis level. Apoptosis was assessed using terminal uridine-triphosphate nick-end labeling (TUNEL) assay, flow cytometry, and confocal microscopy. Leukocyte influx into the peritoneal cavity was confirmed in both models. At all time points, and in both models, there was increased immediate apoptosis in PEC compared with unmanipulated controls and this increase was maximal in CLP after 18 h, although it appeared to remain at a stable level in the sterile peritonitis model by 3 h. There was also an increase in PEC delayed apoptosis at early time points in both models, again maximal at 18 h for CLP, with the levels being significantly higher than the thioglycollate model at 6 h and 18 h. The mice had a relative peripheral neutropenia at 6 h after CLP, but not post thioglycollate injection, and this persisted until 42 h. Lung and liver MPO levels were elevated in CLP but did not increase after thioglycollate. There was no increase in immediate peripheral leukocyte apoptosis in either model, but an increase in delayed peripheral leukocyte apoptosis was observed by 18 h in both models. Peripheral leukocyte CD11b expression, which is a marker of activation, was also persistently elevated in the CLP model, but not in sterile peritonitis. In conclusion, CLP is a more potent stimulus for apoptosis of leukocytes than their migration to the site of inflammation alone, as occurs in the thioglycollate model. Blood leukocyte apoptosis also appears not to be dependent on CD11b expression, and therefore activation status. [ABSTRACT FROM AUTHOR]

Information was sought on the antigen-presenting cells (APC) required for stimulating primary mixed-lymphocyte reactions (MLR) by unprimed Lyt-2 cells in the absence of added iymphokines. Like L3T4 cells, Lyt-2 cells gave very high MLR in response to H-2-different dendritic cells (DC). Surprisingly, high MLR were also elicited by thioglycollate-induced peritoneal exudate cells (PEC), including la− PEC; these cells were non-immunogenic for L3T4 cells. Since PEC consisted almost entirely of macrophages (MΦ), the data suggest that at least two different cell types, DC and MΦ, can express APC function for unprimed Lyt-2+ cells. Since resident peritoneal MΦ and cultured PEC were poorly immunogenic, the APC function of MΦ might be limited to a subset of these cells, e.g. to immature MΦ. [ABSTRACT FROM PUBLISHER]

• A specific diagnosis of Perkinsus olseni was obtained with a new qPCR assay. • The results of the real-time PCR assay were sensitive and reproducible. • No false negatives were obtained with the qPCR assay compared with traditional methods. • Gill tissue provided more accurate qPCR results than those of hemolymph samples. Perkinsus olseni is a protozoan parasite that infects a wide variety of molluscs worldwide, causing economic losses in the aquaculture sector. In the present study, a quantitative PCR (qPCR) assay was developed for the detection and quantification of P. olseni in clam gill tissue and hemolymph (Ruditapes philippinarum and R. decussatus) , and the results were compared with those of the standard diagnostic methods recommended by the O.I.E. (World Organisation for Animal Health): Ray's fluid thioglycollate culture method (RFTM), a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay and histopathology. The efficiency, sensitivity and reproducibility of the newly described qPCR assay were also determined. The highest prevalence was detected using the qPCR assay, and the strongest linear correlation was obtained between the RFTM infection levels and the threshold cycle (Ct) number from the gill tissue. Although better results were obtained from gill than from the hemolymph in the qPCR assays, especially with lower infection levels of the parasite, a significant linear correlation was observed between Ct values from the gill and hemolymph. The qPCR assay that was developed in this study showed high sensitivity, specificity and reproducibility for the detection and quantification of P. olseni. [ABSTRACT FROM AUTHOR]

The macrophage displays functional and phenotypic diversity, which appears, in no small part, to stem from the ability of macrophages to adapt functionally to changes in their tissue microenvironment. Here, we describe the differential activity of peritoneal macrophages with or without the presence of thioglycollate (TG), an inflammatory drug that encouraged the recruitment of macrophages, during aging. The peritoneal-resident macrophages dramatically reduced in phagocytosis and pro-inflammatory cytokines secretion with aging, whereas the functions of macrophages recruited by TG were not significantly changed with aging. These results suggest that macrophages may be changed by their environment in advanced age, and could provide possible explanations for the controversial results regarding differential changes in macrophages in other papers., Competing Interests: CONFLICT OF INTEREST STATEMENT: None declared., (© Chonnam Medical Journal, 2020.)

This work evaluated the acute inflammatory response induced by injections of 0.5 mL saline solution (control), 500 µg carrageenin and 0.5 mL thioglycollate 3% in the swim bladder of juvenile tambacu hybrid. Fish were distributed in three treatments, three replications and acclimated for a period of 10 days before assay. The cell characterization from the inflammatory exudate was performed in Giemsa and PAS stained smears. Carrageenin, injected in fish, showed an increase on the total number of cells in the inflammatory exudate when compared to saline and thioglycollate injected. Whereas, for carrageenin-injected fish, the percentage of thrombocyte was higher than thioglycollate. On the other hand, granulocyte percentage in thioglycollate-injected fish was higher than the ones injected using carrageenin. Carrageenin provoked the highest migration of macrophage to the inflammatory site. The PAS method confirmed the presence of three types of granulocytes: eosinophilic granular cell (EGC) type 1 with the characteristics of a special granulocytic cell commonly found in the circulating blood; EGC type 2 shorter than the last one and neutrophil. This study contributes to a better understanding of the inflammatory response and infectious processes in native fish.

Macrophages play a major role in inflammation, wound healing, and tissue repair. Infiltrated monocytes differentiate into different macrophage subtypes with protective or pathogenic activities in vascular lesions. In the heart and vascular tissues, pathological activation promotes cardiovascular inflammation and remodeling and there is increasing evidence that macrophages play important mechanisms in this environment. Primary murine macrophages can be obtained from: bone marrow by different treatments (granulocyte-macrophage colony-stimulating factor-GM-CSF, macrophage colony-stimulating factor-M-CSF or supernatant of murine fibroblast L929), peritoneal cavity (resident or thioglycolate elicit macrophages), from the lung (alveolar macrophages) or from adipose tissue. In this chapter we describe some protocols to obtain primary murine macrophages and how to identify a pure macrophage population or activation phenotypes using different markers.

Plasminogen (PLG) is the zymogen of plasmin, the major enzyme that degrades fibrin clots. In addition to its binding and activation on fibrin clots, PLG also specifically interacts with cell surfaces where it is more efficiently activated by PLG activators, compared with the reaction in solution. This results in association of the broad-spectrum proteolytic activity of plasmin with cell surfaces that functions to promote cell migration. Here, we review emerging data establishing a role for PLG, plasminogen receptors and the newly discovered plasminogen receptor, Plg-RKT, in macrophage recruitment in the inflammatory response, and we address mechanisms by which the interplay between PLG and its receptors regulates inflammation., (© 2014 Elsevier Inc. All rights reserved.)