Production of LPS-induced inflammatory mediators in murine peritoneal macrophages: neocuproine as a broad inhibitor and ATP7A as a selective regulator

Deriving a Boolean dynamics to reveal macrophage activation with in vitro temporal cytokine expression profiles

BACKGROUND

Macrophages show versatile functions in innate immunity, infectious diseases, and progression of cancers and cardiovascular diseases. These versatile functions of macrophages are conducted by different macrophage phenotypes classified as classically activated macrophages and alternatively activated macrophages due to different stimuli in the complex in vivo cytokine environment. Dissecting the regulation of macrophage activations will have a significant impact on disease progression and therapeutic strategy. Mathematical modeling of macrophage activation can improve the understanding of this biological process through quantitative analysis and provide guidance to facilitate future experimental design. However, few results have been reported for a complete model of macrophage activation patterns.

RESULTS

We globally searched and reviewed literature for macrophage activation from PubMed databases and screened the published experimental results. Temporal in vitro macrophage cytokine expression profiles from published results were selected to establish Boolean network models for macrophage activation patterns in response to three different stimuli. A combination of modeling methods including clustering, binarization, linear programming (LP), Boolean function determination, and semi-tensor product was applied to establish Boolean networks to quantify three macrophage activation patterns. The structure of the networks was confirmed based on protein-protein-interaction databases, pathway databases, and published experimental results. Computational predictions of the network evolution were compared against real experimental results to validate the effectiveness of the Boolean network models.

CONCLUSION

Three macrophage activation core evolution maps were established based on the Boolean networks using Matlab. Cytokine signatures of macrophage activation patterns were identified, providing a possible determination of macrophage activations using extracellular cytokine measurements.

Type I collagen or gelatin stimulates mouse peritoneal macrophages to aggregate and produce pro-inflammatory molecules through upregulated ROS levels

BACKGROUND

Extracellular matrix (ECM) comprising the environments of multicellular society has a dynamic network structure. Collagen is one of the ubiquitous components of ECM. Collagen affects the inflammatory response by regulating the release of pro-inflammatory cytokines from cells. Gelatin, denatured collagen found temporally in tissues, is supposed to be pathophysiologically involved in tissue remodeling, inflammation caused by tissue damage. Previous reports indicate that, phorbol myristate (PMA)-stimulated human U937 (lymphoma cell line) cells that are often used as macrophage-like cells, show cell aggregations when cultured on type I collagen (col I) or gelatin-coated dishes, accompanying the changes of production and release of proinflammatory factors. However, it still remains to be examined whether collagen and gelatin affects normal macrophages as well.

AIM

This study aims to investigate the effect of col. I, the main component of collagenous protein and its denatured product, gelatin, on mouse peritoneal macrophages (MPMs).

METHODS

MTT assay, flow cytometric analysis of ROS, biochemical detection of antioxidant levels, ELISA assay, and western blot were used.

RESULTS

MPMs formed multicellular aggregates on col. I - and gelatin-coated dishes with a concentration- and time-dependent manner. Further studies showed that the culture on col. I and gelatin up-regulated the protein expression and secretion of pro-inflammatory molecules such as IL-1β, TNFα and prostaglandin E₂ (PGE₂) in MPMs. The levels were higher in the cells on gelatin than those on col. I. ROS levels are significantly increased in the cells cultured on both col. I- and gelatin-coated dishes, accompanying decreased levels of antioxidant enzyme catalase (CAT) and anti-oxidant glutathione (GSH), and enhanced nuclear translocation of NF-κB.

CONCLUSION

Col I - or gelatin-coated culture induced the formation of multicellular aggregates and increased production of NF-κB-associated pro-inflammatory molecules in MPMs through up-regulation of ROS levels.

Behind the Link between Copper and Angiogenesis: Established Mechanisms and an Overview on the Role of Vascular Copper Transport Systems

Angiogenesis critically sustains the progression of both physiological and pathological processes. Copper behaves as an obligatory co-factor throughout the angiogenic signalling cascades, so much so that a deficiency causes neovascularization to abate. Moreover, the progress of several angiogenic pathologies (e.g. diabetes, cardiac hypertrophy and ischaemia) can be tracked by measuring serum copper levels, which are being increasingly investigated as a useful prognostic marker. Accordingly, the therapeutic modulation of body copper has been proven effective in rescuing the pathological angiogenic dysfunctions underlying several disease states. Vascular copper transport systems profoundly influence the activation and execution of angiogenesis, acting as multi-functional regulators of apparently discrete pro-angiogenic pathways. This review concerns the complex relationship among copper-dependent angiogenic factors, copper transporters and common pathological conditions, with an unusual accent on the multi-faceted involvement of the proteins handling vascular copper. Functions regulated by the major copper transport proteins (CTR1 importer, ATP7A efflux pump and metallo-chaperones) include the modulation of endothelial migration and vascular superoxide, known to activate angiogenesis within a narrow concentration range. The potential contribution of prion protein, a controversial regulator of copper homeostasis, is discussed, even though its angiogenic involvement seems to be mainly associated with the modulation of endothelial motility and permeability.

Isolation, Culture, and Polarization of Murine Bone Marrow-Derived and Peritoneal Macrophages

Macrophages are the most specialized phagocytic cells, and acquire specific phenotypes and functions in response to a variety of external triggers. Culture of bone marrow-derived or peritoneal macrophages from mice represents an exceptionally powerful technique to investigate macrophage phenotypes and functions in response to specific stimuli, resembling as much as possible the conditions observed in various pathophysiological settings. This chapter outlines protocols used to isolate and culture murine bone marrow-derived and peritoneal macrophages. Furthermore, we describe how these macrophages can be "polarized" to obtain specific macrophage subsets with special relevance to atherosclerosis.

Counteract of bone marrow of blotchy mice against the increases of plasma copper levels induced by high-fat diets in LDLR-/- mice

BACKGROUND

Bone marrow of blotchy mouse (blotchy marrow) reflects the function of transmembrane domain and relevant intramembrane sites of ATP7A in myeloid cells. By chronic infusion of angiotensin II, we previously found that blotchy marrow plays a minor role in regulating plasma copper. Moreover, the recipients of blotchy marrow presented a moderate reduction of plasma lipids and inflammatory mediator production. Little is known about whether these changes are a specific response to angiotensin II or reveal a more general role of ATP7A.

OBJECTIVE AND DESIGN

We investigated if blotchy marrow reduces plasma lipids and inflammatory mediators induced by high-fat diets. To test this hypothesis, blotchy and control marrows were reconstituted to the recipient mice (irradiated male LDLR-/- mice), followed by high-fat-diet feeding for 4 months. At the end points, plasma metals (copper, zinc and iron), lipid profiling (cholesterol, triglyceride, phospholipids and lipoprotein) and six inflammatory mediators (lymphotacin, MCP3, MCP5, TIMP1, VEGF-A and IP-10) were measured. Parallel experiments were performed using male LDLR-/- mice fed either high-fat diets or chow diets for 4 months.

RESULTS

In addition to hyperlipidemia and low-grade inflammation, high-fat diets selectively increased plasma copper concentration compared to chow diets in LDLR-/- mice. After high-fat-diet feeding, the recipients with blotchy marrow showed a decrease in plasma copper (p < 0.01) and an increase in plasma iron (p < 0.05). The recipients with blotchy marrow also presented decreases in cholesterol (p < 0.01) and phospholipids (p < 0.05) in plasma. Surprisingly, plasma levels of MCP3 (p < 0.05), MCP5 (p < 0.05), TIMP1 (p < 0.01), VEGF-A (p < 0.01) and IP-10 (p < 0.01) were significantly increased in the recipients with blotchy marrow compared to controls; the increased levels of MCP3, MCP5 and TIMP1 were more than 50%.

CONCLUSION

Our studies showed that blotchy marrow counteracts the increased copper levels induced by high-fat diets, indicating that circulating myeloid cells can regulate blood copper levels via ATP7A. Moreover, transplantation of blotchy marrow followed by high-fat diets leads to a decrease in lipid profile and an increase in inflammatory mediator production. Overall, blotchy marrow mediates divergent responses to angiotensin II and high-fat diets in vivo.

Bone marrow from blotchy mice is dispensable to regulate blood copper and aortic pathologies but required for inflammatory mediator production in LDLR-deficient mice during chronic angiotensin II infusion

BACKGROUND

The blotchy mouse caused by mutations of ATP7A develops low blood copper and aortic aneurysm and rupture. Although the aortic pathologies are believed primarily due to congenital copper deficiencies in connective tissue, perinatal copper supplementation does not produce significant therapeutic effects, hinting additional mechanisms in the symptom development, such as an independent effect of the ATP7A mutations during adulthood.

METHODS

We investigated if bone marrow from blotchy mice contributes to these symptoms. For these experiments, bone marrow from blotchy mice (blotchy marrow group) and healthy littermate controls (control marrow group) was used to reconstitute recipient mice (irradiated male low-density lipoprotein receptor -/- mice), which were then infused with angiotensin II (1,000 ng/kg/min) for 4 weeks.

RESULTS

By using Mann-Whitney U test, our results showed that there was no significant difference in the copper concentrations in plasma and hematopoietic cells between these 2 groups. And plasma level of triglycerides was significantly reduced in blotchy marrow group compared with that in control marrow group (P < 0.05), whereas there were no significant differences in cholesterol and phospholipids between these 2 groups. Furthermore, a bead-based multiplex immunoassay showed that macrophage inflammatory protein (MIP)-1β, monocyte chemotactic protein (MCP)-1, MCP-3, MCP-5, tissue inhibitor of metalloproteinases (TIMP)-1, and vascular endothelial growth factor (VEGF)-A production was significantly reduced in the plasma of blotchy marrow group compared with that in control marrow group (P < 0.05). More important, although angiotensin II infusion increased maximal external aortic diameters in thoracic and abdominal segments, there was no significant difference in the aortic diameters between these 2 groups. Furthermore, aortic ruptures, including transmural breaks of the elastic laminae in the abdominal segment and lethal rupture in the thoracic segment, were observed in blotchy marrow group but not in control marrow group; however, there was no significant difference in the incidence of aortic ruptures between these 2 groups (P = 0.10; Fisher's exact test).

CONCLUSIONS

Overall, our study indicated that the effect of bone marrow from blotchy mice during adulthood is dispensable in the regulation of blood copper, plasma cholesterol and phospholipids levels, and aortic pathologies, but contributes to a reduction of MIP-1β, MCP-1, MCP-3, MCP-5, TIMP-1, and VEGF-A production and triglycerides concentration in plasma. Our study also hints that bone marrow transplantation cannot serve as an independent treatment option.