Collagen-chitosan 3-D nano-scaffolds effects on macrophage phagocytosis and pro-inflammatory cytokine release

Macrophages are effector cells in the innate and adaptive immune systems and in situ exist within three-dimensional (3-D) microenvironments. As there has been an increase in interest in the use of 3-D scaffolds to mimic natural microenvironments in vitro, this study examined the impact on cultured mice peritoneal macrophages using standard 2-D plates as compared to 3-D collagen-chitosan scaffolds. Here, 2-D and 3-D cultured macrophages were evaluated for responses to lipopolysaccharide (LPS), dexamethasone (Dex), BSA (bovine serum albumin), safranal (herbal component isolated from safranal [Saf]) and Alyssum homolocarpum mucilage (A. muc: mixed herbal components). After treatments, cultured macrophages were evaluated for viability, phagocytic activity and release of tumor necrosis factor (TNF)-α and interleukin (IL)-1β pro-inflammatory cytokines. Comparison of 2-D vs 3-D cultures showed that use of either system – with or without any exogenous agent – had no effect on cell viability. In the case of cell function, macrophages cultured on scaffolds had increases in phagocytic activity relative to that by cells on 2-D plates. In general, the test herbal components Saf and A. muc. had more impact than any of the other exogenous agents on nanoparticle uptake. With respect to production of TNFα and IL-1β, compared to the 2-D cells, scaffold cells tended to have significantly different levels of production of each cytokine, with the effect varying (higher or lower) depending on the test agent used. However, unlike with particle uptake, here, while Saf and A. muc. led to significantly greater levels of cytokine formation by the 3-D culture cells vs that by the 2-D plate cells, there was no net effect (stimulatory) vs control cultures. These results illustrated that collagen-chitosan scaffolds could provide a suitable 3-D microenvironment for macrophage phagocytosis and could also impact on the formation of pro-inflammatory cytokines.     

FAM19A4 is a novel cytokine ligand of formyl peptide receptor 1 (FPR1) and is able to promote the migration and phagocytosis of macrophages

FAM19A4 is an abbreviation for family with sequence similarity 19 (chemokine (C–C motif)-like) member A4, which is a secretory protein expressed in low levels in normal tissues. The biological functions of FAM19A4 remain to be determined, and its potential receptor(s) is unclarified. In this study, we demonstrated that FAM19A4 was a classical secretory protein and we verified for the first time that its mature protein is composed of 95 amino acids. We found that the expression of this novel cytokine was upregulated in lipopolysaccharide (LPS)-stimulated monocytes and macrophages and was typically in polarized M1. FAM19A4 shows chemotactic activities on macrophages and enhances the macrophage phagocytosis of zymosan both in vitro and in vivo with noticeable increases of the phosphorylation of protein kinase B (Akt). FAM19A4 can also increase the release of reactive oxygen species (ROS) upon zymosan stimulation. Furthermore, based on receptor internalization, radio ligand binding assays and receptor blockage, we demonstrated for the first time that FAM19A4 is a novel ligand of formyl peptide receptor 1 (FPR1). The above data indicate that upon inflammatory stimulation, monocyte/macrophage-derived FAM19A4 may play a crucial role in the migration and activation of macrophages during pathogenic infections.     

Immunoevasion and immunosuppression of the macrophage by Mycobacterium tuberculosis

By virtue of their position at the crossroads between the innate and adaptive immune response, macrophages play an essential role in the control of bacterial infections. Paradoxically, macrophages serve as the natural habitat to Mycobacterium tuberculosis (Mtb). Mtb subverts the macrophage's mechanisms of intracellular killing and antigen presentation, leading ultimately to the development of tuberculosis (TB) disease. Here, we describe mechanisms of Mtb uptake by the macrophage and address key macrophage functions that are targeted by Mtb-specific effector molecules enabling this pathogen to circumvent host immune response. The macrophage functions described in this review include fusion between phagosomes and lysosomes, production of reactive oxygen and nitrogen species, antigen presentation and major histocompatibility complex class II expression and trafficking, as well as autophagy and apoptosis. All these are Mtb-targeted key cellular pathways, normally working in concert in the macrophage to recognize, respond, and activate ‘proper’ immune responses. We further analyze and discuss major molecular interactions between Mtb virulence factors and key macrophage proteins and provide implications for vaccine and drug development.     

Modification of nitrite production and phagocytosis of thioglycollate‐elicited mouse peritoneal macrophages by Bovine Casein Digests

The effect of bovine milk casein digests on the ability of thioglycollate‐elicited mouse peritoneal macrophages to produce nitrite and to ingest latex beads was investigated. Intact α s₁‐casein and κ‐casein significantly inhibited nitrite production by the macrophages. The inhibitory activity of the latter was little influenced by trypsin or chymotrypsin digestion, while that of the former decreased with increasing proteinase digestion time. In contrast, pepsin digestion changed the inhibitory activity of a s₁‐casein and κ‐casein into an enhancing activity. Intact ß‐casein, however, had an enhancing effect on nitrite production, and its activity increased noticeably when the protein was digested with pepsin. The enhancing activity of pepsin digests of each casein component reduced when the digest was treated with carboxypeptidase A. Moreover, a trypsin or chymotrypsin digest of α s₁‐casein and κ‐casein inhibited ingestion of latex beads by the macrophages, while a pepsin digest of each casein component enhanced it. These results suggest that the neonate ingestion of infant formula made with bovine milk might reduce resistance to infection via suppression of macrophage functions, such as antimicrobial nitrogen intermediate production and phagocytosis in their gut mucosa, since it is known that gastric secretion and pepsin activity are weak in neonates and the major portion of the caseins ingested by neonates leaves the stomach after minimal digestion.     

红景天苷对小鼠腹腔巨噬细胞体外增殖、凋亡、吞噬、ROS和NO产生的影响

目的:研究红景天苷(Sal)对小鼠腹腔巨噬细胞体外增殖、凋亡、吞噬、胞内活性氧簇(ROS)及分泌一氧化氮(NO)的影响,初步探讨其对小鼠腹腔巨噬细胞的免疫调节作用。方法:无菌分离小鼠腹腔巨噬细胞,并制备单细胞悬液,以不同终浓度(80μmol/L、160μmol/L及320μmol/L)的Sal和巨噬细胞共培养4 h,再以脂多糖(LPS)和γ-干扰素(IFN-γ)进行共刺激。利用MTT比色法检测Sal对巨噬细胞体外增殖的影响。用放线菌酮(CHX)诱导巨噬细胞凋亡,用Sytox G reen染色结合荧光酶标仪检测Sal对CHX诱导巨噬细胞凋亡的影响。用流式细胞术(FCM)检测Sal对巨噬细胞吞噬功能的影响。用2-7-二氯氢化荧光素乙二脂(H2DCFDA)染色法结合荧光酶标仪检测Sal对胞内ROS产生的影响;用G riess反应检测Sal对巨噬细胞分泌NO的影响。结果:MTT比色法检测显示,终浓度为80、160、320μmol/L的Sal均可显著促进LPS+IFN-γ刺激巨噬细胞增殖(P<0.05)。荧光酶标仪检测Syto xG reen染色法的结果显示,160μmol/L的Sal可抑制CHX诱导的巨噬细胞凋亡(P<0.01)。FCM结果显示,各浓度的Sal均能促进单纯药物组和实验药物组LPS+IFN-γ刺激巨噬细胞的吞噬功能(P<0.05)。用荧光酶标仪检测DH2DCFDA染色结果表明,各浓度的Sal对LPS+IFN-γ刺激的巨噬细胞胞内ROS的产生均具有显著的抑制作用(P<0.01)。Griess反应检测NO含量的结果显示,各浓度的Sal对LPS+IFN-γ刺激巨噬细胞产生NO均具有促进作用(P<0.05)。结论:Sal对LPS和IFN-γ刺激的巨噬细胞增殖具有显著的促进作用,对CHX诱导的巨噬细胞凋亡具有显著的抑制作用,对静息态和活化态的巨噬细胞的吞噬功能均有增强作用,并能减少LPS和IFN-γ活化的巨噬细胞胞内ROS的产生;但能促进LPS和IFN-γ活化的巨噬细胞NO的分泌。     

人参皂甙Rb1对小鼠腹腔巨噬细胞体外吞噬及细胞因子和NO分泌的影响

目的:研究人参皂甙Rb1(Ginsenoside Rb1)对小鼠腹腔巨噬细胞体外吞噬及细胞因子和一氧化氮(NO)分泌的影响。方法:分离制备小鼠腹腔巨噬细胞悬液;MTT法检测不同终浓度的人参皂甙Rb1对巨噬细胞的毒性;流式细胞术检测Rb1对巨噬细胞吞噬直径1μm微球的影响;用Griess试剂盒检测Rb1对巨噬细胞NO量的影响;使用流式液相蛋白定量检测技术Cytometric Bead Array(CBA)检测Rb1对LPS刺激巨噬细胞分泌细胞因子的影响。结果:终浓度为5、10、20μmol/L的Rb1对巨噬细胞的吞噬功能具有促进作用,明显抑制LPS诱导的吞噬作用(P<0.05);Rb1能抑制巨噬细胞NO的产生(P<0.01);Rb1能够调节LPS诱导的细胞因子的产生。结论:Rb1对巨噬细胞可能具有双向调节作用,通过抑制LPS信号的转导,调节巨噬细胞因子的分泌,抑制其活化,使NO减少;对于未活化的巨噬细胞,可能通过上调其吞噬功能,增强固有免疫系统来抵御病原体侵入。     

In vitro and in vivo macrophage function can occur independently of SLP-76

Expression of SH2 domain-containing leukocyte-specific phosphoprotein of 76 kDa (SLP-76), a hematopoietic cell-specific adapter protein, is required to couple Syk family tyrosine kinase activation to downstream mediators such as phospholipase C (PLC)-gamma following TCR, platelet collagen receptor and mast cell Fc epsilon R stimulation. In addition to T cells, mast cells and platelets, SLP-76 is expressed in monocytes and macrophages. To determine the role of SLP-76 in Fc gamma R-stimulated signaling pathways in macrophages, we examined cultured bone marrow-derived macrophages (BMM) from SLP-76(-/-) and wild-type mice. In this study, we show that Fc gamma R cross-linking rapidly induces tyrosine phosphorylation of SLP-76 in wild-type BMM. Surprisingly, however, BMM from SLP-76(-/-) mice activate ERK2 and phosphorylate PLC-gamma 2 following Fc gamma R ligation. Furthermore, SLP-76(-/-) BMM display normal Fc gamma R-dependent phagocytic function and reactive oxygen intermediate production. SLP-76(-/-) and SLP-76(+/+) BMM secrete comparable levels of IL-12 in response to lipopolysaccharide and IFN-gamma. To examine macrophage function in vivo, SLP-76(-/-) mice were challenged i.v. with Listeria monocytogenes. SLP-76(-/-) mice survive and efficiently contain the acute phase of infection similar to wild-type mice but exhibit a stable chronic infection attributed to the lack of mature T cells. These data show that, although SLP-76 is required to couple Syk family PTK activity to downstream mediators and effector functions in Fc gamma R-induced pathways in some cell types, activation of Fc gamma R-dependent pathways occurs independently of SLP-76 in BM     

干扰P2X_7R基因对RAW264.7细胞增殖和吞噬的影响

目的:应用RNA干扰技术抑制小鼠巨噬细胞RAW264.7细胞P2X7受体(P2X7R)基因的表达,建立稳定干扰细胞株,并观察其对细胞增殖和凋亡的影响。方法:用脂质体法将P2X7R shRNA重组质粒转染至RAW264.7细胞,经G418筛选后获得稳定干扰细胞株。细胞分为野生型(WT)组、阴性对照(NC)组和干扰(sh P2X7R)组。Real-time PCR法检测细胞中P2X7R mRNA的表达,Western blot检测细胞中P2X7R蛋白的表达;CCK-8方法检测细胞生长活性,5-乙炔基-2’-脱氧尿苷(5-ethynyl-2’-deoxyuridine,Ed U)掺入实验检测细胞增殖活性;流式细胞术分析细胞周期的分布和吞噬情况。结果:P2X7R shRNA能明显抑制RAW264.7细胞的P2X7R mRNA和蛋白的表达,抑制率在80%以上。48 h后,sh P2X7R组细胞的生长速度明显高于NC组和WT组(P0.05),增殖期细胞比例明显升高(P0.05),说明下调P2X7R基因能明显促进细胞增殖。sh P2X7R组的细胞周期出现改变,S期和G2/M期的比例明显上升,增殖指数增高(P0.05)。sh P2X7R组的细胞吞噬活性明显高于NC组(P0.05)。结论:本研究成功构建了稳定干扰P2X7R基因表达的小鼠巨噬细胞株RAW264.7,sh P2X7R能够明显促进RAW264.7细胞的增殖,改变了细胞的吞噬活性。     

IGM is required for efficient complement mediated phagocytosis of apoptotic cells in vivo

A variety of complement components have been detected on apoptotic cells and proposed to facilitate recognition and/or ingestion by phagocytes. The triggers for complement activation remain uncertain. To determine the role of IgM in classical pathway activation and clearance of apoptotic cells in vitro and in vivo, we quantified these parameters in mice deficient in serum IgM (sIgM). Phagocytosis by bone marrow-derived macrophages of apoptotic cells incubated with serum deficient in sIgM was markedly reduced, similar to apoptotic cells incubated with C1q deficient serum in vitro. Similarly, intraperitoneal clearance of apoptotic cells and cellular C3 deposition were significantly reduced in mice deficient in sIgM compared to wild-type mice. Clearance and C3 deposition were reconstituted by addback of IgM. In mice deficient in both sIgM and C1q, addback of both serum factors was required for restoration of clearance. These findings indicate that, on a quantitative basis, sIgM is a potent factor required for intraperitoneal phagocytosis of apoptotic cells, and further demonstrate that IgM and C1q work in concert to activate complement, resulting in C3 deposition on the apoptotic cell surface and ultimately, efficient clearance of the apoptotic cell by macrophages.     

Viili多糖对巨噬细胞RAW264.7激活及分泌细胞因子的影响

探讨viili胞外多糖(Viili exopolysaccharides,VEPS)对小鼠巨噬细胞RAW264.7激活和增殖的影响。噻唑蓝(MTT)比色法检测细胞的生长与增殖;中性红吞噬实验检测吞噬活性;Griess试剂盒检测培养上清液中NO分泌量,ELISA法检测VEPS不同浓度及不同作用时间培养上清中IL-6,IL-1β含量;扫描电子显微镜观察VEPS对细胞形态的影响;碘化丙啶(PI)染色检测VEPS对细胞周期的影响。结果显示,VEPS对RAW264.7细胞的增殖、吞噬能力、分泌NO、IL-6、IL-1β等都有显著的促进作用,VEPS为100μg/ml时促进作用最明显,呈剂量相关,作用72h时细胞因子分泌量达到最大,72h后下降。VEPS激活巨噬细胞并使其变得扁平伸展且形成伪足。VEPS促进G1期细胞增多,提高细胞的增殖能力。VEPS免疫调节作用与其激活RAW264.7细胞,促进NO、IL-6、IL-1β等分泌有关,且VEPS与LPS对RAW264.7细胞有相似的作用规律。以上结果证明VEPS能激活巨噬细胞,也可能最终激活淋巴细胞,达到增强非特异性和特异性免疫的作用。     

Innate immunity to intracellular pathogens: macrophage receptors and responses to microbial entry

Innate immunity to intracellular pathogens encompasses a range of interactions of cellular and humoral activities of the host with the invading microorganism, determining the outcome of infection. Here, we review the particular role of macrophage recognition receptors and effector responses in the uptake of microbes and their products. We place this in context and raise issues for discussion and further experimentation.     

Search for potent modulators of cytokine production by macrophages

We compared the effects of Tamerit, Polyoxidony, and Licopid on spontaneous and lipopolysaccharide-stimulated production of interleukin-1 and tumor necrosis factor by mouse peritoneal macrophages in vitro. The test preparations were equally potent in stimulating nonactivated cells. Licopid produced a costimulatory effect on macrophages primed with endotoxin. Tamerit in different doses suppressed cytokine production by cells. Polyoxidony in low doses activated, but in high doses suppressed this process.Translated from Byulleten Eksperimentalnoi Biologii i Meditsiny, Vol. 138, No. 9, pp. 293–295, September, 2004     

Search for potent modulators of cytokine production by macrophages

We compared the effects of Tamerit, Polyoxidony, and Licopid on spontaneous and lipopolysaccharide-stimulated production of interleukin-1 and tumor necrosis factor by mouse peritoneal macrophagesin vitro. The test preparations were equally potent in stimulating nonactivated cells. Licopid produced a costimulatory effect on macrophages primed with endotoxin. Tamerit in different doses suppressed cytokine production by cells. Polyoxidony in low doses activated, but in high doses suppressed this process. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 9, pp. 293–295, September, 2004     

Akt2 is required for macrophage chemotaxis

Tumor‐associated macrophages play an important role in tumorigenesis and metastasis. Trafficking of macrophages to the proximity of tumors is mediated by CSF‐1, a growth factor. In this study, we investigated the role of PKB/Akt in CSF‐1‐induced macrophage migration. Disruption of Akt2 expression by small interference RNA impaired chemotaxis of both THP‐1 cells and mouse peritoneal macrophages. Phosphorylation of PKCζ, an essential component in chemotaxis signaling pathway, was reduced. LIMK/Cofilin, downstream of PKCζ, regulated cytoskeleton rearrangement during cell migration. Disruption of Akt2 expression inhibited CSF‐1‐induced LIMK/Cofilin phosphorylation, which contributed to defects in actin polymerization and chemotaxis. Furthermore, MCP‐1, a chemokine, ‐induced macrophage chemotaxis was also impaired. Taken together, our results demonstrated that Akt2 plays an essential role in both CSF‐1‐ and chemokine‐induced chemotaxis of macrophages.     

Phagocytosis and endocytosis of silver nanoparticles induce interleukin-8 production in human macrophages

Phagocytosis or endocytosis by macrophages is critical to the uptake of fine particles, including nanoparticles, in order to initiate toxic effects in cells. Here, our data enhance the understanding of the process of internalization of silver nanoparticles by macrophages. When macrophages were pre-treated with inhibitors to phagocytosis, caveolin-mediated endocytosis, or clathrin-mediated endocytosis, prior to exposure to silver nanoparticles, Interleukin-8 (IL-8) production was inhibited. Although cell death was not reduced, the inflammatory response by macrophages was compromised by phagocytosis and endocytosis inhibitors.