Patterns Of Macrophage Activation Research Articles

Spatial transcriptomics reveals organized and distinct immune activation in cutaneous granulomatous disorders

BackgroundNon-infectious (inflammatory) cutaneous granulomatous disorders include cutaneous sarcoidosis (CS), granuloma annulare (GA), necrobiosis lipoidica (NL), and necrobiotic xanthogranuloma (NXG). These disorders share macrophage predominant inflammation histologically, but the inflammatory architecture and the pattern of extracellular matrix alteration varies. The underlying molecular explanations for these differences remain unclear. ObjectiveTo understand spatial gene expression characteristics in these disorders. MethodsWe performed spatial transcriptomics in cases of CS, GA, NL, and NXG to compare patterns of immune activation and other molecular features in a spatially resolved fashion. ResultsCS is characterized by a polarized, spatially organized T helper (Th) 1 predominant response with classical macrophage activation. GA is characterized by a mixed, but spatially organized pattern of Th1 and Th2 polarization with both classical and alternative macrophage activation. NL showed concomitant activation of Th1, Th2, and Th17 immunity with a mixed pattern of macrophage activation. Activation of type 1 immunity was shared among, CS, GA, and NL and included upregulation of IL-32. NXG showed upregulation of CXCR4-CXCL12/14 chemokine signaling and exaggerated alternative macrophage polarization. Histologic alteration of extracellular matrix correlated with hypoxia and glycolysis programs and type 2 immune activation. ConclusionsInflammatory cutaneous granulomatous disorders show distinct and spatially organized immune activation that correlate with hallmark histologic changes.

Lung microhaemorrhage drives oxidative/inflammatory damage in α1-antitrypsin deficiency.

Animal models using intratracheal instillation show that elastase, unopposed by α1-antitrypsin (AAT), causes alveolar damage and haemorrhage associated with emphysematous changes. The aim of the present study was to characterise any relationship between alveolar haemorrhage and human AAT deficiency (AATD) using bronchoalveolar lavage (BAL) and lung explant samples from AATD subjects. BAL samples (17 patients, 15 controls) were evaluated for free haem (iron protoporphyrin IX) and total iron concentrations. Alveolar macrophage activation patterns were assessed using RNA sequencing and validated in vitro using haem-stimulated, monocyte-derived macrophages. Lung explants (seven patients, four controls) were assessed for iron sequestration protein expression patterns using Prussian blue stain and ferritin immunohistochemistry, as well as ferritin iron imaging and elemental analysis by transmission electron microscopy. Tissue oxidative damage was assessed using 8-hydroxy-2'-deoxyguanosine immunohistochemistry. BAL collected from AATD patients showed significantly elevated free haem and total iron concentrations. Alveolar and interstitial macrophages in AATD explants showed elevated iron and ferritin accumulation in large lysosomes packed by iron oxide cores with degraded ferritin protein cages. BAL macrophage RNA sequencing showed innate pro-inflammatory activation, replicated in vitro by haemin exposure, which also triggered reactive oxygen species generation. AATD explants showed massive oxidative DNA damage in both lung epithelial cells and macrophages. BAL and tissue markers of alveolar haemorrhage, together with molecular and cellular evidence of macrophage innate pro-inflammatory activation and oxidative damage, are consistent with free haem stimulation. Overall, this initial study provides evidence for a pathogenetic role of elastase-induced alveolar haemorrhage in AATD emphysema.

Sepsis with liver dysfunction and coagulopathy predicts an inflammatory pattern of macrophage activation

BackgroundInterleukin-1 receptor antagonists can reduce mortality in septic shock patients with hepatobiliary dysfunction and disseminated intravascular coagulation (HBD + DIC), an organ failure pattern with inflammatory features consistent with macrophage activation. Identification of clinical phenotypes in sepsis may allow for improved care. We aim to describe the occurrence of HBD + DIC in a contemporary cohort of patients with sepsis and determine the association of this phenotype with known macrophage activation syndrome (MAS) biomarkers and mortality. We performed a retrospective nested case–control study in adult septic shock patients with concurrent HBD + DIC and an equal number of age-matched controls, with comparative analyses of all-cause mortality and circulating biomarkers between the groups. Multiple logistic regression explored the effect of HBD + DIC on mortality and the discriminatory power of the measured biomarkers for HBD + DIC and mortality.ResultsSix percent of septic shock patients (n = 82/1341) had HBD + DIC, which was an independent risk factor for 90-day mortality (OR = 3.1, 95% CI 1.4–7.5, p = 0.008). Relative to sepsis controls, the HBD + DIC cohort had increased levels of 21 of the 26 biomarkers related to macrophage activation (p < 0.05). This panel was predictive of both HBD + DIC (sensitivity = 82%, specificity = 84%) and mortality (sensitivity = 92%, specificity = 90%).ConclusionThe HBD + DIC phenotype identified patients with high mortality and a molecular signature resembling that of MAS. These observations suggest trials of MAS-directed therapies are warranted.

Meta-Inflammation and Metabolic Reprogramming of Macrophages in Diabetes and Obesity: The Importance of Metabolites.

Diabetes mellitus type II and obesity are two important causes of death in modern society. They are characterized by low-grade chronic inflammation and metabolic dysfunction (meta-inflammation), which is observed in all tissues involved in energy homeostasis. A substantial body of evidence has established an important role for macrophages in these tissues during the development of diabetes mellitus type II and obesity. Macrophages can activate into specialized subsets by cues from their microenvironment to handle a variety of tasks. Many different subsets have been described and in diabetes/obesity literature two main classifications are widely used that are also defined by differential metabolic reprogramming taking place to fuel their main functions. Classically activated, pro-inflammatory macrophages (often referred to as M1) favor glycolysis, produce lactate instead of metabolizing pyruvate to acetyl-CoA, and have a tricarboxylic acid cycle that is interrupted at two points. Alternatively activated macrophages (often referred to as M2) mainly use beta-oxidation of fatty acids and oxidative phosphorylation to create energy-rich molecules such as ATP and are involved in tissue repair and downregulation of inflammation. Since diabetes type II and obesity are characterized by metabolic alterations at the organism level, these alterations may also induce changes in macrophage metabolism resulting in unique macrophage activation patterns in diabetes and obesity. This review describes the interactions between metabolic reprogramming of macrophages and conditions of metabolic dysfunction like diabetes and obesity. We also focus on different possibilities of measuring a range of metabolites intra-and extracellularly in a precise and comprehensive manner to better identify the subsets of polarized macrophages that are unique to diabetes and obesity. Advantages and disadvantages of the currently most widely used metabolite analysis approaches are highlighted. We further describe how their combined use may serve to provide a comprehensive overview of the metabolic changes that take place intracellularly during macrophage activation in conditions like diabetes and obesity.

Anti-Leishmania activity of extracts from Piper cabralanum C.DC. (Piperaceae).

Species of Piperaceae are known by biological properties, including antiparasitic such as leishmanicidal, antimalarial and in the treatment of schistosomiasis. The aim of this work was to evaluate the antileishmania activity, cytotoxic effect, and macrophage activation patterns of the methanol (MeOH), hexane (HEX), dichloromethane (DCM) and ethyl acetate (EtOAc) extract fractions from the leaves of Piper cabralanum C.DC. The MeOH, HEX and DCM fractions inhibited Leishmanina amazonensis promastigote-like forms growth with a half maximal inhibitory concentration (IC50) of 144.54, 59.92, and 64.87μg/mL, respectively. The EtOAc fraction did not show any relevant activity. The half maximal cytotoxic concentration (CC50) for macrophages were determined as 370.70, 83.99, 113.68 and 607μg/mL for the MeOH, HEX and DCM fractions, respectively. The macrophage infectivity was concentration-dependent, especially for HEX and DCM. MeOH, HEX and DCM fractions showed activity against L.amazonensis with low cytotoxicity to murine macrophages and lowering infectivity by the parasite. Our results provide support for in vivo studies related to a potential application of P.cabralanum extract and fractions as a promising natural resource in the treatment of leishmaniasis.

Regulation of macrophage subsets and cytokine production in leishmaniasis

Macrophages are host cells for parasites of the genus Leishmania where they multiply inside parasitophorous vacuoles. Paradoxically, macrophages are also the cells responsible for killing or controlling parasite growth, if appropriately activated. In this review, we will cover the patterns of macrophage activation and the mechanisms used by the parasite to circumvent being killed. We will highlight the impacts of the vector bite on macrophage activation. Finally, we will discuss the ontogeny of macrophages that are infected by Leishmania spp.

Macrophage Activation in the Synovium of Healthy and Osteoarthritic Equine Joints.

Synovitis is a major component of osteoarthritis and is driven primarily by macrophages. Synovial macrophages are crucial for joint homeostasis (M2-like phenotype), but induce inflammation (M1-like) when regulatory functions become overwhelmed. Macrophage phenotypes in synovium from osteoarthritic and healthy joints are poorly characterized; however, comparative knowledge of their phenotypes during health and disease is paramount for developing targeted treatments. This study compared patterns of macrophage activation in healthy and osteoarthritic equine synovium and correlated histology with cytokine/chemokine profiles in synovial fluid. Synovial histology and immunohistochemistry for M1-like (CD86), M2-like (CD206, IL-10), and pan macrophage (CD14) markers were performed on biopsies from 29 healthy and 26 osteoarthritic equine joints. Synovial fluid cytokines (MCP-1, IL-10, PGE2, IL-1β, IL-6, TNF-α, IL-1ra) and growth factors (GM-CSF, SDF-1α+β, IGF-1, and FGF-2) were quantified. Macrophage phenotypes were not as clearly defined in vivo as they are in vitro. All macrophage markers were expressed with minimal differences between OA and normal joints. Expression for all markers increased proportionate to synovial inflammation, especially CD86. Synovial fluid MCP-1 was higher in osteoarthritic joints while SDF-1 and IL-10 were lower, and PGE2 concentrations did not differ between groups. Increased CD14/CD86/CD206/IL-10 expression was associated with synovial hyperplasia, consistent with macrophage recruitment and activation in response to injury. Lower synovial fluid IL-10 could suggest that homeostatic mechanisms from synovial macrophages became overwhelmed preventing inflammation resolution, resulting in chronic inflammation and OA. Further investigations into mechanisms of arthritis resolution are warranted. Developing pro-resolving therapies may provide superior results in the treatment of OA.

Immunometabolic Status of COVID-19 Cancer Patients.

Cancer patients appear to be more likely to be diagnosed with coronavirus disease 2019 (COVID-19). This is supported by the understanding of immunometabolic pathways that intersect patients with infection and cancer. However, data derived by case series and retrospective studies do not offer a coherent interpretation, since data from China suggest an increased risk of COVID-19, while data from the United States and Italy show a prevalence of COVID-19 in cancer patients comparable with the general population. Noteworthy, cancer and COVID-19 exploit distinct patterns of macrophage activation that promote disease progression in the most severe forms. In particular, the alternative activation of M2-polarized macrophages plays a crucial role in cancer progression. In contrast, the macrophage-activation syndrome appears as the source of M1-related cytokine storm in severe COVID-19 disease, thus indicating macrophages as a source of distinct inflammatory states in the two diseases, nonetheless as a common therapeutic target. New evidence indicates that NAMPT/NAD metabolism can direct both innate immune cell effector functions and the homeostatic robustness, in both cancer and infection. Moreover, a bidirectional relationship exists between the metabolism of NAD and the protective role that angiotensin converting enzyme 2, the COVID-19 receptor, can play against hyperinflammation. Within this immunometabolic framework, the review considers possible interference mechanisms that viral infections and tumors elicit on therapies and provides an overview for the management of patients with cancer affected by COVID-19, particularly for the balance of risk and benefit when planning normally routine cancer treatments and follow-up appointments.

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

BackgroundMacrophages 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.ResultsWe 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.ConclusionThree 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.

The role of polyamines in the regulation of macrophage polarization and function.

Naturally occurring polyamines are ubiquitously distributed and play important roles in cell development, amino acid and protein synthesis, oxidative DNA damage, proliferation, and cellular differentiation. Macrophages are essential in the innate immune response, and contribute to tissue remodeling. Naïve macrophages have two major potential fates: polarization to (1) the classical pro-inflammatory M1 defense response to bacterial pathogens and tumor cells, and (2) the alternatively activated M2 response, induced in the presence of parasites and wounding, and also implicated in the development of tumor-associated macrophages. ODC, the rate-limiting enzyme in polyamine synthesis, leads to an increase in putrescine levels, which impairs M1 gene transcription. Additionally, spermidine and spermine can regulate translation of pro-inflammatory mediators in activated macrophages. In this review, we focus on polyamines in macrophage activation patterns in the context of gastrointestinal inflammation and carcinogenesis. We seek to clarify mechanisms of innate immune regulation by polyamine metabolism and potential novel therapeutic targets.

Monocyte-macrophage activation is associated with nonalcoholic fatty liver disease and liver fibrosis in HIV monoinfection independently of the gut microbiome and bacterial translocation.

Nonalcoholic fatty liver disease (NAFLD) is common among people living with HIV. There are limited data available on the pathophysiology of NAFLD and the development of fibrosis in this population. The aim of this study was to investigate the association of bacterial translocation, adipose tissue dysfunction, monocyte activation and gut dysbiosis in patients with HIV monoinfection and NAFLD. Cases with biopsy-proven NAFLD and HIV monoinfection were age and sex-matched to HIV-positive and HIV-negative controls. Markers of bacterial translocation [lipopolysaccharide-binding protein (LBP), bacterial DNA and lipopolysaccharide (LPS)], adipose tissue dysfunction (leptin, adiponectin) and monocyte activation (sCD14 and sCD163) were measured by ELISA. Hepatic patterns of macrophage activation were explored with immunohistochemistry. 16 s rRNA sequencing was performed with stool. Thirty-three cases were included (≥F2 fibrosis n = 16), matched to HIV-positive (n = 29) and HIV-negative (n = 17) controls. Cases with NAFLD were more obese (BMI 31.0 ± 4.4 vs. 24.1 ± 2.8 kg/m, P < 0.001) and had significantly increased levels of sCD14, sCD163 and higher leptin to adiponectin ratio vs. HIV-positive controls. Cases with ≥F2 verses < F2 fibrosis had increased sCD14 (1.4 ± 0.4 vs. 1.1 ± 0.3 μg/ml, P = 0.023) and sCD163 (1.0 ± 0.3 vs. 0.8 ± 0.3 μg/ml, P = 0.060), which correlated with waist circumference (sCD14 P = 0.022, sCD163 P = 0.011). Immunohistochemistry showed increased hepatic portal macrophage clusters in patients with fibrosis. No markers of bacterial translocation or changes to the microbiome were associated with NAFLD or fibrosis. NAFLD fibrosis stage in HIV monoinfected patients is associated with monocyte activation in the context of obesity, which may be independent of bacterial translocation and gut microbiome.

Stimulation of bovine monocyte-derived macrophages with lipopolysaccharide, interferon-\u0263, Interleukin-4 or Interleukin-13 does not induce detectable changes in nitric oxide or arginase activity

BackgroundBacterial lipopolysaccharide and interferon-γ stimulation of rodent macrophages in vitro induces up-regulation of inducible nitric oxide synthase, whereas interleukin-4 stimulation results in increased activity of arginase-1. Thus different stimulants result in differing macrophage phenotypes, appropriate for responses to a range of pathogens. The current study was conducted in order to determine whether bovine macrophages derived from monocytes and spleen respond similarly.ResultsLipopolysaccharide and interferon-γ did not induce detectable increases in nitric oxide production by bovine monocyte-derived or splenic macrophages in vitro. Similarly, interleukin-4 and interleukin-13 did not affect arginase activity. However, changes in transcription of genes coding for these products were detected.ConclusionDifferences between macrophage activation patterns exist between cattle and other species and these differences may occur during the post-transcription phase.

Comparison of Polyvinyl Alcohol (PVA) vs Collagen Sponges to Assess Macrophage Activation Patterns in Rats

Statement of PurposeAll implanted materials induce an immune response driven by macrophages called the foreign body reaction (FBR). Macrophages exist in a continuum of highly inflammatory to highly pro‐wound healing phenotypic cell types. This project aims to assess macrophage activation patterns caused by implanted polyvinyl alcohol non‐biodegradable vs. collagen biodegradable sponges in the subcutaneous space of male Sprague Dawley rats. Our hypothesis is that macrophages interact differently between different materials. If such difference exists, this means the approaches to driving macrophages to their wound healing states would be expected to be different. This study included the delivery of previously tested drug modulators, dexamethasone and iloprost, for their ability to shift macrophages to their pro‐wound healing state. The use of these modulators enables screening and comparing the effect of biomaterial chemistry on macrophage activation patterns.MethodsMale Sprague‐Dawley rats, (250 – 290) grams, were divided into three groups (6 animals in groups #1 and #2 and 4 animals in group #3) where PVA sponges were soaked in either the vehicle solution (lactate Ringers' solution) in group #1 (control group), 100 μM dexamethasone in group #2 (treatment group), or 1 nM iloprost in group #3 (treatment group). Two PVA sponges were implanted in the dorsal subcutaneous space of each animal. A daily booster dose of the assigned treatment was administered subcutaneously into each implantation site 24 hours after implantation until experiment completion. A week after implantation, sponges and surrounding tissue were harvested for either histological/immunohistochemical analysis or CCL2 quantification.ResultsC‐C motif chemokine ligand 2 (CCL2) levels averaged around 800, 450, and 300 ng/mL in the wound fluid collected from the control, iloprost treated, and dexamethasone‐treated sponges, respectively. The levels of CCL2 in the wound fluid collected from the dexamethasone‐treated sponges and those collected from the iloprost treated sponges were found to be significantly less than the wound fluid levels of CCL2 from the control sponges. No significant difference was found between the wound fluid levels of CCL2 from dexamethasone‐treated sponges vs. iloprost‐treated sponges (Figure 1).Less cellular density and less collagen formation were observed in the tissues surrounding both iloprost treated sponges and dexamethasone‐treated sponges compared to the tissues around the control sponges (Figure 2).The total protein concentrations in the wound fluid collected from control and treatment sponges were similar within each animal and ranged between 40–50 mg/mL.Additional experiments are needed to determine the macrophage activation response after the implantation of collagen bio‐degradable sponges and compare it to macrophage activation response after the implantation of PVA non‐biodegradable sponges.Support or Funding InformationProvost's Collaborative Research Grant at University of ArkansasThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Understanding mechanisms of the umbilical cord-derived multipotent mesenchymal stromal cell-mediated recovery enhancement in rat model of limb ischemia

Umbilical cord-derived multipotent mesenchymal stromal cells (UC-MMSCs) are considered as a strong candidate for cell therapy of lower limb ischemia. Sustained calf muscle ischemia with aseptic inflammatory response was induced in Sprague-Dawley rats by excision of femoral and popliteal arteries. uC-MSCs were injected into the calf muscle on day 7 after surgery. The animals were sacrificed on days 3, 10, and 30 after transplantation. Animals responded to the transplantation by temporary improvement in their locomotor function as assessed by the rota-rod performance test. Measured size of the lesions was significantly smaller in the experimental group than in the control group at all time points throughout the observation. The transplantation stimulated angiogenic processes on day 10 after transplantation. Living transplanted cells were traced for up to 30 days after transplantation, during which time they migrated to the damaged area to be partially eliminated by host macrophages; none of them differentiated into endothelial or smooth muscle cells of blood vessels. Additionally, the transplantation led to the predominance of activated pro-angiogenic and anti-inflammatory M2 macrophages by inhibiting the CD68+ macrophage infiltration and stimulating the CD206+ macrophage activation at the site of injury. A single intramuscular injection of allogeneic umbilical cord-derived mesenchymal stromal cells reproducibly facilitated recovery of structural and functional properties of surgically ischemized calf muscles in a rat. No differentiation of the transplanted cells in vivo was observed. The transplantation negatively regulated inflammation and enhanced tissue repair chiefly by modulating local patterns of macrophage activation.

Abstract 11833: Lipid-rich Core Quantification in Carotid Atherosclerosis Using MRI T2 Mapping - Relation to Clinical Presentation and Plaque Macrophage Activation

Introduction: Non-invasive plaque lipid quantification is appealing both for treatment selection and as predictor of future plaque events. However, current MRI methods are insensitive, require a coalesced mass of lipid and rely on multicontrast acquisition. We sought to: (1) provide tissue validation of quantitative T2 maps to measure plaque lipid; and (2) investigate whether this technique could discern differences in plaque characteristics between symptomatic and asymptomatic plaques. We also hypothesised that plaque lipid content correlates with differential plaque macrophage activation. Methods: 40 patients scheduled for carotid endarterectomy were recruited for 3T carotid MRI. Lipid Area was derived from segmented T2 maps and compared directly to plaque lipid defined by histology. Plaque macrophages were procured using laser-capture microdissection from frozen tissue and subjected to microarray analysis. Results: Lipid Area (%) on T2 mapping and histology showed excellent correlation, both by individual slices (R = 0.85, P &lt; 0.001) and plaque average (R = 0.83, P &lt; 0.001). Lipid Area (%) on T2 maps was significantly higher in symptomatic compared to asymptomatic plaques (31.5 ± 3.7% vs. 15.8 ± 3.1%, P = 0.005) despite similar degrees of carotid stenosis. ROC curve analysis showed that T2 mapping has a fair to good ability to discriminate between symptomatic and asymptomatic plaques. Finally, using gene set enrichment analysis, plaque lipid content by T2 map positively correlated with distinct patterns of macrophage activation e.g. INF-STAT1 pathway (P &lt; 0.01, FDR &lt; 0.25). Conclusions: MRI T2 mapping accurately quantifies plaque lipid non-invasively. Greater plaque lipid content was found in symptomatic plaques; and this correlated with inflammatory pathway activation in plaque macrophages. This new technique may find a role in determining optimum treatment e.g. providing an indication for intensive lipid-lowering, or anti-inflammatory therapy.

Phenotypic changes in the brain of SIV-infected macaques exposed to methamphetamine parallel macrophage activation patterns induced by the common gamma-chain cytokine system.

One factor in the development of neuroAIDS is the increase in the migration of pro-inflammatory CD8 T cells across the blood–brain barrier. Typically these cells are involved with keeping the viral load down. However, the persistence of above average numbers of CD8 T cells in the brain, not necessarily specific to viral peptides, is facilitated by the upregulation of IL15 from astrocytes, in the absence of IL2, in the brain environment. Both IL15 and IL2 are common gamma chain (γc) cytokines. Here, using the non-human primate model of neuroAIDS, we have demonstrated that exposure to methamphetamine, a powerful illicit drug that has been associated with HIV exposure and neuroAIDS severity, can cause an increase in molecules of the γc system. Among these molecules, IL15, which is upregulated in astrocytes by methamphetamine, and that induces the proliferation of T cells, may also be involved in driving an inflammatory phenotype in innate immune cells of the brain. Therefore, methamphetamine and IL15 may be critical in the development and aggravation of central nervous system immune-mediated inflammatory pathology in HIV-infected drug abusers.

The activation pattern of macrophages in giant cell (temporal) arteritis and primary angiitis of the central nervous system

To determine if the pattern of macrophage activation reflects differences in the pathogenesis and clinical presentation of giant cell arteritis and primary angiitis of the central nervous system, specimens of 10 patients with giant cell arteritis and five with primary angiitis of the central nervous system were immunohistochemically studied and the expression of the macrophage activation markers 27E10, MRP14, MRP8 and 25F9 was determined in the vasculitic infiltrates. Thus, a partly different expression pattern of macrophage activation markers in giant cell arteritis and primary angiitis of the central nervous system was observed. The group comparison revealed that giant cell arteritis cases had significantly higher numbers of acute activated MRP14-positive macrophages, whereas primary angiitis of the central nervous system is characterized by a tendency toward more MRP8-positive intermediate/late activated macrophages. Furthermore, in giant cell arteritis comparably fewer CD8-positive lymphocytes were observed. These observations suggest, that despite their histopathological similarities, giant cell arteritis and primary angiitis of the central nervous system appear to represent either distinct entities within the spectrum of granulomatous vasculitides or different stages of similar disease processes. Their discrete clinical presentation is reflected by different activation patterns of macrophages, which may characterize giant cell arteritis as a more acute process and primary angiitis of the central nervous system as a more advanced inflammatory process.

The Alveolar Microenvironment of Patients Infected with Human Immunodeficiency Virus Does Not Modify Alveolar Macrophage Interactions with Streptococcus pneumoniae

We tested the hypothesis that HIV infection results in activation of alveolar macrophages and that this might be associated with impaired defense against pneumococcus. We compared alveolar macrophages and lymphocytes in 131 bronchoalveolar lavage samples from HIV-infected and healthy controls using inflammatory gene microarrays, flow cytometry, real-time PCR, and enzyme-linked immunosorbent assay (ELISA) to determine the pattern of macrophage activation associated with HIV infection and the effect of this activation on defense against pneumococcus. We used gamma interferon (IFN-γ) priming to mimic the cellular milieu in HIV-infected lungs. InnateDB and BioLayout 3D were used to analyze the interactions of the upregulated genes. Alveolar macrophages from HIV-infected adults showed increased gene expression and cytokine production in a classical pattern. Bronchoalveolar lavage from HIV-infected subjects showed excess CD8(+) lymphocytes with activated phenotype. Toll-like receptor 4 (TLR4) expression was increased in macrophages from HIV-infected subjects, but function was similar between the groups; lung lavage fluid did not inhibit TLR function in transfected HeLa cells. Alveolar macrophages from HIV-infected subjects showed normal binding and internalization of opsonized pneumococci, with or without IFN-γ priming. Alveolar macrophages from HIV-infected subjects showed classical activation compared to that of healthy controls, but this does not alter macrophage interactions with pneumococci.

The role of immunity and inflammation in the development of diabetic complications

Our group has carried out pivotal clinical studies on large cohorts of type 1 and type 2 diabetes to determine the impact of modified LDL-IC as well as inflammatory cytokines/adipokines and acute-phase reactant proteins in the development of diabetic complications. We have demonstrated that high levels of specific LDL modifications in circulating ICs correlate with increased risk for the development and progression of macrovascular disease, nephropathy, and retinopathy, frequently exceeding conventional risk factors in their predictive power. In cardiovascular disease, differences in the type of LDL modification and the stage of disease seem to lead to/predict different outcomes. The differences observed with ICs containing different types of modified LDL raises interesting questions about the role of the predominant LDL modification in the ICs and the cellular patterns of macrophage activation, survival, and apoptosis that result from LDL-IC ingestion. The differences observed in the predictive power of modified LDL-ICs at different stages of CVD development strongly suggest that modified LDL-ICs are causally related with the development of atherosclerosis and/or plaque instability. The association of cytokines/adipokines and acute-phase reactant proteins with the development of complications in type 1 diabetes is less strong than that observed with modified LDL-ICs and occurs at a later phase of the development of complications. In conclusion, the human humoral autoimmune response to modified forms of LDL is a typical adaptive response, with a switch to IgG synthesis and increasing antibody affinity that leads to the release of proinflammatory mediators, and it has unquestionable pathogenic characteristics.

Mathematical modeling and stability analysis of macrophage activation in left ventricular remodeling post-myocardial infarction

BackgroundAbout 6 million Americans suffer from heart failure and 70% of heart failure cases are caused by myocardial infarction (MI). Following myocardial infarction, increased cytokines induce two major types of macrophages: classically activated macrophages which contribute to extracellular matrix destruction and alternatively activated macrophages which contribute to extracellular matrix construction. Though experimental results have shown the transitions between these two types of macrophages, little is known about the dynamic progression of macrophages activation. Therefore, the objective of this study is to analyze macrophage activation patterns post-MI.ResultsWe have collected experimental data from adult C57 mice and built a framework to represent the regulatory relationships among cytokines and macrophages. A set of differential equations were established to characterize the regulatory relationships for macrophage activation in the left ventricle post-MI based on the physical chemistry laws. We further validated the mathematical model by comparing our computational results with experimental results reported in the literature. By applying Lyaponuv stability analysis, the established mathematical model demonstrated global stability in homeostasis situation and bounded response to myocardial infarction.ConclusionsWe have established and validated a mathematical model for macrophage activation post-MI. The stability analysis provided a possible strategy to intervene the balance of classically and alternatively activated macrophages in this study. The results will lay a strong foundation to understand the mechanisms of left ventricular remodelling post-MI.