Abstract: Objectives: Acute lung injury (ALI) is still a leading cause of morbidity and mortality in critically ill patients. ALI can be induced by sepsis, ventilator, hyperoxia, and ischemia-reperfusion. In the management of ALI, studies have shown that low concentration hydrogen has a therapeutic effect on acute lung injury. The present study was designed to investigate the effects and corresponding mechanism of the inhalation of hydrogen on ALI. Methods: C57 male mice underwent intraperitoneal injection of lipopolysccharide (LPS) to induce sepsis. Then, the mice were given 2% hydrogen. The survival rate, lung injury, inflammatory factors and macrophage phenotypic changes were assessed in bronchoalveolar lavage fluid (BALF). In vitro experiment, we obtained primary mouse bone mar- row-derived macrophages (BMDM) incubated by LPS to explore the anti-inflammatory effects and corresponding mechanism. Results: Treatment with 2% hydrogen showed a substantial attenuation of inflammations, adverse lung histopathological changes and decreased M1 macrophage phenotypes while increased M2 macrophage pheno- types. Importantly, the decreased M1 macrophage phenotypes while increased M2 macrophage phenotypes were observed in LPS-stimulated macrophages treated with 2% hydrogen. Further, we observed significantly low levels of TNFα in LPS-induced macrophages treated with 2% hydrogen. The effects were ascribed to an inhibition of phos- phorylation of p38 MAPK. Conclusion: 2% hydrogen may reduce sepsis-induced inflammatory responses in animals and in macrophages, and the inhibition to the activation of the MAPK/TNF-α may contribute to this protection.
This study provides novel insights into the presence of intramacrophage E. coli and lamina propria macrophage phenotypes in relation to the presence or absence of intracellular E. coli in Crohn’s disease. Further work is required to determine the pathogenic significance of these macrophage subtypes in CD. Clarification of whether E. coli -laden macrophages are attempting to ameliorate inflammation or whether they contribute to microbial persistence and disease pathogenesis will also be im- portant. This may lead to therapies aimed at manipula- tion of macrophage phenotypes [13, 14] and renewed interest in the use of antibiotics that target intracellu- lar E. coli for the treatment of CD .
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Figure 2 Macrophages in atherosclerotic plaque development. A-C representative heterogeneous foam cells from carotid atherosclerotic plaques. A: CD86 (brown), B: CD163 (brown) ADRP (green), C: CD206 (brown). D and E: macrophage collagen I expression. D: CD163 (green), procollagen I (red), nuclei (blue), CD163 and procollagen I co-expression (yellow). Inset: closer magnification of the cell in D indicated by white arrow head. E: CD86 (green: examples indicated by white arrow heads), procollagen I (red), nuclei (blue). Note, no CD86/procollagen I co-expression is evident as seen by absence of yellow. F: Proposed role of macrophage involvement in plaque progression. Lipoprotein enters the vessel wall where it is retained, in part, by binding to proteoglycans. Monocytes are recruited into the atherosclerotic plaque where they differentiate into different macrophage phenotypes (predominantly M2 in the early plaque) and uptake modified lipid adopting heterogenous foam cell forms (see also A-C). Apoptosis of the macrophages, in particular M2, is accompanied by efferocytosis, also primarily by M2 macrophages. As the plaque adopts an increasingly inflammatory environment, M1 foam cells predominate and defective efferocytosis increases, with subsequent necrosis leading to the formation of the necrotic core. In the advanced plaque, intraplaque haemorrhage promotes the formation of Mhem macrophages, which are athero-protective, partly due to reduced lipid accumulation and the production of collagen I. In contrast, M1 macrophages accumulate in the shoulder of the plaque contributing to thinning of the cap through MMP production. The destabilisation of the plaque leads to rupture of the plaque and thrombus formation. IPH = intraplaque haemorrhage, MV = microvessels, M ϕ = macrophage, PG = proteoglycan.
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Pulmonary infection is a major cause of mortality and morbidity, and the magnitude of the lung inflammatory response corre- lates with patient survival. Previously, we have shown that neutrophil migration into joints is regulated by arthritis severity quantita- tive trait loci (QTLs). However, it is unclear whether these QTLs contribute to the regulation of lung inflammation in pneumonias. Therefore, to more clearly define the factors regulating acute inflammatory responses in the lung, we examined two inbred rat strains, DA and F344, that differ in these QTLs and their susceptibility to joint inflammation. Staphylococcal cell wall components lipoteichoic acid (LTA) and peptidoglycan (PGN), administered intratracheally, significantly increased the numbers of neutrophils retrieved in the bronchoalveolar lavage fluid (BALF). F344 had approximately 10-fold more neutrophils in the BALF compared with DA (P < 0.001) and higher BALF concentrations of total protein, tumor necrosis factor- α and macrophage inflammatory protein 2. LTA/PGN administration in DA × F344 congenic strains (Cia3d, Cia4, Cia5a, and Cia6) resulted in inflammation similar to that in DA, demonstrating that the genes responsible for the differences in pulmonary inflammation are not contained within the chromoso- mal intervals carried by these congenic strains. Alveolar macrophages (AMs) isolated from naïve F344 stimulated in vitro with LTA/PGN produced significantly higher levels of keratinocyte-derived chemokine and macrophage inflammatory protein 2 than alveolar macrophages from DA rats. The differences were related to differential mitogen-activated protein kinase phosphoryla- tion. We conclude that the factors contributing to inflammation can be site and challenge dependent. A better understanding of site-specific inflammation may lead to more effective treatment of acute lung inflammation and injury.
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A key role of macrophages is antigen presentation and the evidence indicates that M1 macrophages are more effective antigen presenting cells than M2 macrophages. MHCII expression is a hallmark of antigen-presenting cells and is robustly increased on BMDMs prepared from aged rats and, while its expression on cells from young rats is increased following IFNy treatment, the effect of IFNy is greater in cells from aged rats; this contrasts with the lack of effect of LPS on MHCII mRNA. M1 activation of macrophages is also associated with an increase in the expression of CD80, CD86 and CD40, which enable increased interaction with T cells. For example CD40 ligand is expressed on T cells, this receptor-ligand interaction leads to increased production of pro- inflammatory cytokines (Lynch, 2009), and inhibiting this CD40-CD40 ligand interaction has been demonstrated to be beneficial in an animal model of MS (Gerritse et al., 1996). The present data also show that there is an age-related increase in expression of CD40 mRNA and a genotype-dependent response to IFNy which mirrors the change in MHCII mRNA. M2 macrophages are thought to be poor antigen presenting cells and exhibit low expression of costimulatory molecules (Edwards et al., 2006). In support of this, it has been that while IFNy induced an increase in antigen presentation in the macrophage cell line J774A.1, the anti-inflammatory cytokine TGF-(5 was shown to have an opposite effect (Delvig et al., 2002).
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In short, this study demonstrates that different ADMs, processed and manufactured using different methods, elicit differing patterns and timeframes of macrophage infiltration. Although direct cause and effect relation- ships remain to be explored, there appears to be a strong correlation between macrophage subtypes and remodel- ing response. Further work to elucidate these findings over longer periods of time and within the context of clinical use and outcomes could lead to rational choices in use of these materials for differing clinical applica- tions.
ABSTRACT Caspase recruitment domain-containing protein 9 (CARD9) is a critical adaptor molecule triggered by the interaction of C-type lectin receptors (CLRs) with carbohydrate motifs found in fungi. Consequently, clinical and animal studies indi- cate that CARD9 is an important regulator of protective immunity against fungal pathogens. Previous studies suggest that CARD9 is important for the induction of protection against Cryptococcus neoformans, an opportunistic fungal pathogen that causes life-threatening infections of the central nervous system in immunocompro- mised patients. However, the effect of CARD9 deﬁciency on the induction of protec- tive immune responses against C. neoformans is unknown. Immunization with a C. neoformans mutant that overexpresses the transcription factor zinc ﬁnger 2, denoted LW10, results in protection against an otherwise lethal challenge with wild-type (WT) C. neoformans. Our results showed that CARD9 is essential for the induction of vaccine-mediated immunity against C. neoformans infection. We observed signiﬁcant decreases in interleukin-17 (IL-17) production and signiﬁcant increases in Th2-type cytokine (IL-4, IL-5, and IL-13) production in CARD9-deﬁcient mice after inoculation with strain LW10. While leukocyte inﬁltration to the lungs of CARD9-deﬁcient mice was similar in LW10 and WT C. neoformans-infected mice, macrophages derived from CARD9-deﬁcient mice inherently skewed toward an M2 activation phenotype, were unable to contain the growth of LW10, and failed to produce nitric oxide in re- sponse to infection with LW10 or stimulation with lipopolysaccharide. These results suggest that CARD9-mediated signaling is required for M1 macrophage activation and fungicidal activity necessary for the induction of vaccine-mediated immunity against C. neoformans.
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significant smaller adipocytes than ob/ob mice without EA, which correlated with a lower number of infiltrating macrophages. Obesity-associated low-grade inflamma- tion characterized by an increased abundance of macro- phages in the adipose tissue is recognized as a key step in the pathogenesis of insulin resistance . Using im- munohistochemistry, we noted increased numbers of F4/80 macrophages positive cells as well as F4/80 gene expression in white adipose tissue derived from ob/ob mice as compared to lean control. Increased number of adipose tissue macrophages mainly in visceral depots is associated with adipocyte hypertrophy, insulin resist- ance, activation of stress-signaling pathways, increases in autophagy and apoptosis . Macrophage infiltration into adipose tissue increases proportionally with in- creased BMI, body fat mass and adipocyte hypertrophy and represents a reversible process in obese patients loosing weight [18, 19]. Thus, the decrease in adiposity attributed to EA might be related to its potential direct efficacy in reducing both the macrophage infiltration and the related genes expression of inflammation. Inter- estingly, our data indicate that the obesity-associated in- crease in adipose macrophages can be prevented by the
activated macrophages in the pathogenesis of SSc. Mac- rophages have been thought to be particularly activated in patients with skin disease including SSc and are poten- tially important sources for fibrosis-inducing cytokines, such as TGF-β [7,8]. In addition, activated circulating monocytes have also been reported in SSc patients, sup- porting a possible involvement of these cells in the patho- genesis of this disease [20,21]. However, no link between CD163 + or CD204 + monocyte/macrophage lineage and
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TME is intricate and consists of heterogeneous subsets of myeloid cells. Growing tumor is capable of modulating antitumor myeloid cells to protumor myeloid cells through secreted factors. M1–M2 polarization of myeloid cells resulted into immunosuppressive and protumor phenotypes. Other category of myeloid cells that exerts protumor func- tion in microenvironment is called MDSCs. All the tumor- promoting myeloid subsets are characterized by the surface markers, secretory factors, and their functions in the microen- vironment. Tumor-promoting myeloid cells inhibit antitumor immunity and thus, enhance tumor growth. Next, we have discussed the contribution of key myeloid populations in the therapeutic responses.
basement membrane; this process has been postulated to require remodeling of the ECM. Plasminogen (Plg) is a protease that binds to the ECM and, upon conversion to plasmin, degrades multiple ECM proteins. In addition, plasmin directly activates MMPs. Here, we used Plg –/– mice to investigate the role of Plg in inflammatory leukocyte migration. After induction of peritonitis by thioglycollate injection, we found that Plg –/– mice displayed diminished macrophage trans-ECM migration and decreased MMP-9 activation. Furthermore, injection of the active form of MMP-9 in Plg –/– mice rescued macrophage migration in this model. We used periaortic application of CaCl 2 to induce abdominal aortic aneurysm (AAA) and found that Plg –/– mice displayed reduced macrophage infiltration and were protected from aneurysm formation. Administration of active MMP-9 to Plg –/– mice promoted macrophage infiltration and the development of AAA. These data suggest that Plg regulates macrophage migration in inflammation via activation of MMP-9, which, in turn, regulates the ability of the cells to migrate across ECM. Thus, targeting the Plg/MMP-9 pathway may be an attractive approach to regulate inflammatory responses and AAA development.
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fraction of infected macrophages gradually increases. An anal- ysis of HIV-1 decay in patients with symptomatic disease (mean CD4 ⫹ T-cell counts of 212/ l) indicated that 1 to 7% of the plasma virus was being produced by long-lived infected cells, assumed to be tissue macrophages (30). In AIDS patients with very low numbers of circulating CD4 ⫹ T lymphocytes ( ⬍ 50 cells/ l), high levels of cell-associated HIV-1 DNA be- come detectable in lung, colon, brain, liver, and kidney, pre- sumably reflecting the presence of productively infected tissue macrophages in these organs (4, 9). It has also been suggested that the coexistence of opportunistic infections can greatly augment the number of productively HIV-1-infected cells of the monocyte/macrophage lineage (29).
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ABSTRACT Macrophages are the primary targets of Mycobacterium tuberculosis in- fection; the early events of macrophage interaction with M. tuberculosis deﬁne sub- sequent progression and outcome of infection. M. tuberculosis can alter the innate immunity of macrophages, resulting in suboptimal Th1 immunity, which contributes to the survival, persistence, and eventual dissemination of the pathogen. Recent ad- vances in immunometabolism illuminate the intimate link between the metabolic states of immune cells and their speciﬁc functions. In this review, we describe the little-studied biphasic metabolic dynamics of the macrophage response during pro- gression of infection by M. tuberculosis and discuss their relevance to macrophage immunity and M. tuberculosis pathogenicity. The early phase of macrophage infec- tion, which is marked by M1 polarization, is accompanied by a metabolic switch from mitochondrial oxidative phosphorylation to hypoxia-inducible factor 1 alpha (HIF-1 ␣ )-mediated aerobic glycolysis (also known as the Warburg effect in cancer cells), as well as by an upregulation of pathways involving oxidative and antioxida- tive defense responses, arginine metabolism, and synthesis of bioactive lipids. These early metabolic changes are followed by a late adaptation/resolution phase in which macrophages transition from glycolysis to mitochondrial oxidative metabolism, with a consequent dampening of macrophage proinﬂammatory and antimicrobial re- sponses. Importantly, the identiﬁcation of upregulated metabolic pathways and/or metabolic regulatory mechanisms with immunomodulatory functions during M1 po- larization has revealed novel mechanisms of M. tuberculosis pathogenicity. These ad- vances can lead to the development of novel host-directed therapies to facilitate bacterial clearance in tuberculosis by targeting the metabolic state of immune cells.
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We sought mesangial cell-derived paracrine regulators for macrophage production of gelatinase B. NR8383 macrophages were exposed to serial dilutions of mesangial cell- derived medium, stimulated with or without LPS, and zymographic analysis was performed on the conditioned media. Unexpectedly, the mesangial cell-derived medium did not induce but inhibited the production of gelatinase B by activated macrophages in a dose-dependent manner (Figure 3.16A.). Basal expression of gelatinase B was also repressed by the mesangial cell-conditioned medium (data not shown). At concentrations higher than 25 %, the inducible gelatinase B activity was abolished by the treatment with mesangial cell-derived medium. This inhibition of enzymatic activity was not due to induction of metalloproteinase inhibitors, since expression levels of gelatinase A were unaltered. Furthermore, Northern blot analysis revealed that activated macrophages in co-culture with mesangial cells exhibited a markedly depressed expression of gelatinase B mRNA compared to stimulated macrophages not in co-culture (Figure 3.16B.).
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belong to the mononuclear phagocyte system and are derived from blood-borne monocytes that migrate into tissues, where they undergo final differentiation. Tumour hypoxia is an important stimulus for extravasation of mono- cytes , which migrate into the tumour tissue along gra- dients of chemoattractants, and these TAMs become immobilized in ischaemic, necrotic areas of tumours, where they can remain for an extended time [15–18]. Many studies have linked increased TAM density to poor prognosis in breast cancer [15,19–21], and in fact certain genetic alterations that increase the malignancy of the tumour may concomitantly increase the degree of macrophage infiltration. A strong association has been reported between HER-2, c-myc and int-2 oncogene amplification in breast tumour samples and the density of lymphocyte infiltration of the tumour . In inflammatory breast cancer, expression of constitutively activated RhoC oncoprotein is associated with concomitant upregulation of both angiogenic (vascular endothelial growth factor [VEGF]) and inflammatory (IL-6) cytokines, leading to the formation of a specific type of inflammatory/angiogenic stroma in this particularly aggressive form of disease . Some of the tumour molecular alterations that increase macrophage infiltration and macrophage-mediated angio- genesis include increased expression of monocyte chemoattractant protein (MCP)-1 and VEGF, both of which are highly expressed in breast tumour cells. MCP-1, a member of the C–C chemokine family, is involved in mono- cyte and T-lymphocyte migration, and is secreted by many human and murine tumour cells in addition to activated stromal cells [24,25]. MCP-1 expression in tumour cells is significantly correlated with the extent of TAM infiltration [26,27], and in particular both MCP-1 and VEGF expres- sion have been positively correlated with TAM infiltration, angiogenesis and poor survival in breast cancer [28–30]. VEGF is a potent angiogenic growth factor that is over- expressed in the majority of human cancers . VEGF produced by tumours promotes the proliferation, survival and migration of endothelial cells by binding to its recep- tors, namely VEGF receptor (VEGFR)-1 and VEGFR-2, which are expressed on the endothelial cell surface. However, in addition to these direct effects on endothelial cells, VEGF also stimulates monocyte migration through VEGFR-1 , which is expressed on monocytes and macrophages, as well as on endothelial cells [33,34]. A positive correlation between VEGF expression and degree of macrophage infiltration has been observed in invasive breast carcinoma [28,35] and other malignancies [36,37]. Placental growth factor and VEGF-C – two VEGF-related tumour-derived growth factors – can also stimulate mono- cyte chemotaxis [38,39]. Placental growth factor may also act as a survival factor for both endothelial cells and macrophages .
Hematopoiesis is a complex process of cell proliferation and differentiation that is regulated by a variety of CSFs (as discussed above). A number of the interleukin families of cytokines are also known to influence hematopoiesis. IL-3 is one of the major hematopoietic cytokines that play an important role in hematopoiesis associated with inflammation or immune responses. 192 IL-3, also known as multi-lineage CSF, is expressed by mitogen or antigen activated T-lymphocytes, 193,194 natural killer cells, 194 keratinocytes, endothelial cells, monocytes/macrophages, mast cells, 195 neurons and microglial cells. 166, 193 IL-3 was originally identified by its ability to induce the synthesis of 20 - - steroid dehydrogenase in splenic lymphocytes of nude mice. It is a potent growth promoting cytokine that has a very broad spectrum of activities in regulating biological responses such as cell proliferation, survival, growth and differentiation. 194, 195 For example, it plays very important roles in the proliferation and differentiation of a broad range of hematopoietic progenitor cells into erythrocytes, monocytes, macrophages, megakaryocytes, mast cells, basophils, neutrophils, eosinophils, dendritic cells, 195, 196, 197 microglial cells and placental cells. 198 In addition to its effects on the development of different hematopoietic cells, IL- 3 can also enhance antigen presentation for T cell-dependent responses, augment macrophage cytotoxicity and adhesion, promote the secretory function of eosinophils and basophils, participate in inflammation by inducing
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Macrophage polarization and the phenotype alteration are regulated by various cytokines and chemokines. IFN-γ secreted from Th1 cells promotes the M1 polarization, whereas IL-4 and IL-10 secreted from Th2 cells promotes the M2 polarization . Obese diabetics showed significantly increased expres- sion of IFN-γ that was highly associated with TREM-1 over-expression in omentum and liver biopsy samples compared to obese non-diabetics. The results of our study suggest the possible regulatory role of TREM-1 on the secretion of IFN-γ, thereby possibly affecting macrophage polarization and obesity-induced insu- lin resistance [19, 27–29]. The expression of IL-4 in omentum and liver tissues was significantly decreased in obese diabetics compared to obese non-diabetics. We observed that obese diabetics and non-diabetics had a lower number of patients with down regulation of IL-10 in liver biopsy samples. Since IL-10 expres- sion levels are inversely related to IR, potentiating IL-10 may enhance Th2 response, further curbing the (See figure on previous page.)
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The infected female sand fly pushes the parasite’s motile and flagellated stage into the human skin (termed as Promastigote). After entering the leishmania parasite into the human body, it’s intention is to attack and reside in the macrophage tissues. Once the parasite enters into the human host, it is phagocytosed by macrophages and then becomes Amastigote in nature. The Amastigote form is then able to infect additional macrophages locally and distribute by different tissue sites. When uninfected sand fly feeds blood from an infected host, then it becomes infected with Amastigote. Next it transforms back into the Promastigote stage in the sand fly gut depending upon leishmania species and also individual host immune factors .
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Of the classifiers trialled in this study, a random forest classifier with 20 trees was found to be the most accurate in determining immune cell phenotype. A confusion matrix shows the percentage of cells which were correctly classified for each phenotype, Table 3. The classifier exceeded 85% accuracy for M1, M2 and naïve mac- rophages. The most common misclassifications were of monocytes imaged after 6 days with naïve macrophages. Given the very similar nature of day 6 monocytes and naive macrophages, this observation is not very surprising. Nevertheless, this misclassification can be explained by the dominance of cell area as a discerning metric in the decision tree. Whilst other cell types showed distinct distributions of cell area, these two phenotypes exhibit a near identical distribution (Fig. 5A). The large number of decision trees and subsequent nodes involved in a ran- dom forest classifier makes interpretation and location of the error source difficult.
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Abstract: Atherosclerosis is a leading cause of coronary heart disease and stroke. Since 1981, more than 980,000 cases of AIDS have been reported in the United States. According to the Centers for Disease Control, more than 1 million Americans may be infected with HIV. By killing or damaging CD4+ T cells of the body’s immune system, HIV progressively destroys the body’s ability to fight infections. People diagnosed with AIDS often suffer from life-threatening diseases caused by opportunistic infections such as tuberculosis. HIV-infected individuals have increased risks for atherosclerosis. This review summarizes the effects of oxidized low density lipoproteins in impairing macrophage functions in individuals with atherosclerosis (with and without HIV infection) thereby enhancing the susceptibility to Mycobacterium tuberculosis infection.