Macrophage folate receptor-β (FR-β) expression in auto-immune inflammatory rheumatic diseases: A forthcoming marker for cardiovascular risk?

Molecular imaging for evaluation of synovitis associated with osteoarthritis: a narrative review

Recent evidence highlights the role of low-grade synovial inflammation in the progression of osteoarthritis (OA). Inflamed synovium of OA joints detected by imaging modalities are associated with subsequent progression of OA. In this sense, detecting and quantifying synovitis of OA by imaging modalities may be valuable in predicting OA progressors as well as in improving our understanding of OA progression. Of the several imaging modalities, molecular imaging such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) has an advantage of visualizing the cellular or subcellular events of the tissues. Depending on the radiotracers used, molecular imaging method can potentially detect and visualize various aspects of synovial inflammation. This narrative review summarizes the recent progresses of imaging modalities in assessing inflammation and OA synovitis and focuses on novel radiotracers. Recent studies about imaging modalities including ultrasonography (US), magnetic resonance imaging (MRI), and molecular imaging that were used to detect and quantify inflammation and OA synovitis are summarized. Novel radiotracers specifically targeting the components of inflammation have been developed. These tracers may show promise in detecting inflamed synovium of OA and help in expanding our understanding of OA progression.

Combination Therapy with Resveratrol and Celastrol Using Folic Acid-Functionalized Exosomes Enhances the Therapeutic Efficacy of Sepsis

Overactivated macrophages are a prominent feature of many inflammatory and autoimmune diseases, including sepsis. Attention and regulation of macrophages activity is of great significance for sepsis treatment. Herein, this study shows that folic acid-functionalized exosomes accumulate in the lung of septic mice and specifically target inflammatory macrophages. Therefore, FA-functionalized exosomes co-loaded with resveratrol (an anti-inflammatory polyphenol) and celastrol (an immunosuppressive pentacyclic triterpenoid; FA-Exo/R+C), which exhibit powerful anti-inflammatory and immunosuppressive activities against LPS-stimulated macrophages in vitro by regulating NF-κB and ERK1/2 signaling pathways, are designed. Encouraged by these positive data, the efficacy of FA-Exo/R+C is systematically investigated in an LPS-induced mouse sepsis model. FA-Exo/R+C shows striking therapeutic benefits in terms of attenuated cytokine storm, reduced acute lung injury, and increased survival of septic mice by inhibiting the inflammation and proliferation of proinflammatory M1 macrophages. Importantly, multiple administrations of FA-Exo/R+C significantly enhance and prolong the protective effect, and resist rechallenge to LPS. Collectively, the strategy of co-delivering drugs combination through functionalized exosomes offers a new avenue for sepsis treatment.

Aging-associated inflammation and fibrosis in arachnoid membrane

Background

The physiological and pathological significance of the arachnoid membrane (AM) is still unknown. In this study, we investigated various characteristics of the AM, focusing on the influence of inflammation and fibrosis.

Methods

Small pieces of AM sample were obtained during neurosurgical procedures from 74 cases. The clinical and pathological characteristics of the hyperplastic AM group (≥ 50 μm) and the non-hyperplastic AM group (< 50 μm) were compared. Then, potential correlations between AM thickness and clinical characteristics were analyzed. Moreover, VEGFα, TGFβ, and TGFα levels were quantitated by real time PCR. Then, the potential correlations between AM thickness and these inflammatory or anti-inflammatory markers, and the influence of the original disease were calculated.

Results

The median age of the patients in hyperplastic AM group was significantly older than that of the non-hyperplastic AM group. Moreover, the number of fibroblasts, CD68⁺ cells, CD86⁺ cells, and CD206⁺ cells in the hyperplastic AM group was significantly higher than that in the non-hyperplastic AM group. The AM thickness was significantly correlated to age and number of fibroblasts, CD68⁺ cells, CD86⁺ cells, and CD206⁺ cells. The thickness of the AM was significantly correlated to the messenger RNA expression levels of VEGFα (ρ = 0.337), and the VEGFα expression levels were significantly correlated with TGFβ and TNFα.

Conclusions

The AM hyperplasia was influenced by aging and could be a result of inflammation and fibrosis through cytokine secretion from the inflammatory cells and fibroblasts in the AM.

Macrophage lipid accumulation in the presence of immunosuppressive drugs mycophenolate mofetil and cyclosporin A

OBJECTIVE

Mycophenolate (MPA) and cyclosporin A (CsA) are two immunosuppressive agents currently used for the treatment of autoimmune diseases. However, reports regarding their effects on inflammation and lipid handling are controversial. Here, we compare the effect of these two drugs on the expression of proteins involved in cholesterol handling and lipid accumulation in a macrophage cell system utilizing M0, M1 and M2 human macrophages and in murine bone marrow-derived macrophages (BMDM).

METHODS

Differentiated M0, M1 and M2 subsets of THP-1 human macrophages were subjected to various concentrations of either MPA or CsA. Expression of proteins involved in reverse cholesterol transport (ABCA1 and 27-hydroxylase) and scavenger receptors, responsible for uptake of modified lipids (CD36, ScR-A1, CXCL16 and LOX-1), were evaluated by real-time PCR and confirmed with Western blot. DiI-oxidized LDL internalization assay was used to assess foam cell formation. The influence of MPA was also evaluated in BMDM obtained from atherosclerosis-prone transgenic mice, ApoE^-/- and ApoE^-/-Fas^-/-.

RESULTS

In M0 macrophages, MPA increased expression of ABCA1 and CXCL16 in a concentration-dependent manner. In M1 THP-1 macrophages, MPA caused a significant increase of 27-hydroxylase mRNA and CD36 and SR-A1 receptor mRNAs. Exposure of M2 macrophages to MPA also stimulated expression of 27-hydroxylase, while downregulating all evaluated scavenger receptors. In contrast, CsA had no impact on cholesterol efflux in M0 and M1 macrophages, but significantly augmented expression of ABCA1 and 27-hydroxylase in M2 macrophages. CsA significantly increased expression of the LOX1 receptor in naïve macrophages, downregulated expression of CD36 and SR-A1 in the M1 subpopulation and upregulated expression of all evaluated scavenger receptors. However, CsA enhanced foam cell transformation in M0 and M2 macrophages, while MPA had no effect on foam cell formation unless used at a high concentration in the M2 subtype.

CONCLUSIONS

Our results clearly underline the importance of further evaluation of the effects of these drugs when used in atherosclerosis-prone patients with autoimmune or renal disease.

Depletion of activated macrophages with a folate receptor-beta-specific antibody improves symptoms in mouse models of rheumatoid arthritis

Objectives

Most therapies for autoimmune and inflammatory diseases either neutralize or suppress production of inflammatory cytokines produced by activated macrophages (e.g., TNFα, IL-1, IL-6, IL-17, GM-CSF). However, no approved therapies directly target this activated subset of macrophages.

Methods

First, we undertook to examine whether the folate receptor beta (FR-β) positive subpopulation of macrophages, which marks the inflammatory subset in animal models of rheumatoid arthritis, might constitute the prominent population of macrophages in inflamed lesions in humans. Next, we utilized anti-FR-β monoclonal antibodies capable of mediating antibody-dependent cell cytotoxicity (ADCC) to treat animal models of rheumatoid arthritis and peritonitis.

Results

Human tissue samples of rheumatoid arthritis, Crohn’s disease, ulcerative colitis, idiopathic pulmonary fibrosis, nonspecific interstitial pneumonia, chronic obstructive pulmonary disease, systemic lupus erythematosus, psoriasis, and scleroderma are all characterized by dramatic accumulation of macrophages that express FR-β, a protein not expressed on resting macrophages or any other healthy tissues. A monoclonal antibody to FR-β accumulates specifically in inflamed lesions of murine inflammatory disease models and successfully treats such models of rheumatoid arthritis and peritonitis. More importantly, elimination of FR-β-positive macrophages upon treatment with an anti-FR-β monoclonal antibody promotes the departure of other immune cells, including T cells, B cells, neutrophils, and dendritic cells from the inflamed lesions.

Conclusions

These data suggest that specific elimination of FR-β-expressing macrophages may constitute a highly specific therapy for multiple autoimmune and inflammatory diseases and that a recently developed human anti-human FR-β monoclonal antibody (m909) might contribute to suppression of this subpopulation of macrophages.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1912-0) contains supplementary material, which is available to authorized users.

Ginsenoside metabolite compound-K regulates macrophage function through inhibition of β-arrestin2

Ginsenoside metabolite compound-K (C-K), which is an active metabolite of ginsenoside in vivo, can produce anti-inflammatory affects by activating glucocorticoid receptors (GRs) to inhibit the expression of β-arrestin2. Studies have shown that C-K can inhibit the function of immune cells including macrophage polarization and phagocytosis. However, the mechanism by which C-K regulates macrophage polarization is currently unclear. Toll-like receptors (TLRs) are the pattern recognition receptors on the membrane of immune cells, with TLR4 being especially important in polarization of macrophages. The Gαi-mediated activation of nuclear factor-κB (NF-κB) by TLR4 promotes inflammation and phagocytosis in macrophages by increasing the proportion of type I phenotypic macrophages (M1). Whether C-K inhibits the signal transduction of TLR4-Gαi-NF-κB and how that effects macrophage polarization regulation in murine models of RA is not reported. The coupling of G proteins with receptors is regulated by β-arrestin2, but it has been unclear whether C-K modulates the TLR4 interaction with G proteins by inhibiting the expression of β-arrestin2. To explore these questions, the collagen-induced arthritis (CIA) mouse model was employed, and mice were treated with C-K (112 mg/kg/day). The results depict that C-K treatment inhibits macrophage phagocytosis and reduces the proportion of M1. C-K decreases the overexpressed β-arrestin2, Gαi, TLR4 and NF-κB in macrophages of CIA mice, while increasing the expression of Gαs. Furthermore, C-K promotes TLR4-Gαs coupling and inhibits TLR4-Gαi coupling through β-arrestin2 regulation in macrophages, leading to a decrease in the proportion of M1 to M2 macrophages and improved outcomes in CIA mice.

Folic acid deficiency and vision: a review

Folic acid (FA), also termed folate, is an essential vitamin for health at all ages since it participates in the biosynthesis of nucleotides, amino acids, neurotransmitters, and certain vitamins. It is therefore crucial for rapidly growing tissues such as those of the fetus. It is becoming clear that FA deficiency and impaired folate pathways are implicated in many diseases of both early life and old age. FA can be transported into the cell by the folate receptor, the reduced folate transporter, and proton-coupled folate transporter. Folate transport proteins are present in certain eye tissues, which explains why FA plays an important role in eye development. The purpose of this literature review is to investigate the evidence relating FA deficiency to eye diseases.

Inverse Molecular Docking as a Novel Approach to Study Anticarcinogenic and Anti-Neuroinflammatory Effects of Curcumin

Research efforts are placing an ever increasing emphasis on identifying signal transduction pathways related to the chemopreventive activity of curcumin. Its anticarcinogenic effects are presumably mediated by the regulation of signaling cascades, including nuclear factor κB (NF-κB), activator protein 1 (AP-1), and mitogen-activated protein kinases (MAPK). By modulating signal transduction pathways, curcumin induces apoptosis in malignant cells, thus inhibiting cancer development and progression. Due to the lack of mechanistic insight in the scientific literature, we developed a novel inverse molecular docking protocol based on the CANDOCK algorithm. For the first time, we performed inverse molecular docking of curcumin into a collection of 13,553 available human protein structures from the Protein Data Bank resulting in prioritized target proteins of curcumin. Our predictions were in agreement with the scientific literature and confirmed that curcumin binds to folate receptor β, DNA (cytosine-5)-methyltransferase 3A, metalloproteinase-2, mitogen-activated protein kinase 9, epidermal growth factor receptor and apoptosis-inducing factor 1. We also identified new potential protein targets of curcumin, namely deoxycytidine kinase, NAD-dependent protein deacetylase sirtuin-1 and -2, ecto-5'-nucleotidase, core histone macro-H2A.1, tyrosine-protein phosphatase non-receptor type 11, macrophage colony-stimulating factor 1 receptor, GTPase HRas, aflatoxin B1 aldehyde reductase member 3, aldo-keto reductase family 1 member C3, amiloride-sensitive amine oxidase, death-associated protein kinase 2 and tryptophan-tRNA ligase, that may all play a crucial role in its observed anticancer effects. Moreover, our inverse docking results showed that curcumin potentially binds also to the proteins cAMP-specific 3',5'-cyclic phosphodiesterase 4D and 17-β-hydroxysteroid dehydrogenase type 10, which provides a new explanation for its efficiency in the treatment of Alzheimer's disease. We firmly believe that our computational results will complement and direct future experimental studies on curcumin's anticancer activity as well as on its therapeutic effects against Alzheimer's disease.

Novel solid-phase strategy for the synthesis of ligand-targeted fluorescent-labelled chelating peptide conjugates as a theranostic tool for cancer

In this article, we have successfully designed and demonstrated a novel continuous process for assembling targeting ligands, peptidic spacers, fluorescent tags and a chelating core for the attachment of cytotoxic molecules, radiotracers, nanomaterials in a standard Fmoc solid-phase peptide synthesis in high yield and purity. The differentially protected Fmoc-Lys-(Tfa)-OH plays a vital role in attaching fluorescent tags while growing the peptide chain in an uninterrupted manner. The methodology is versatile for solid-phase resins that are sensitive to mild and strong acidic conditions when acid-sensitive side chain amino protecting groups such as Trt (chlorotrityl), Mtt (4-methyltrityl), Mmt (4-methoxytrityl) are employed to synthesise the ligand targeted fluorescent tagged bioconjugates. Using this methodology, DUPA rhodamine B conjugate (DUPA = 2-[3-(1,3-dicarboxypropyl)ureido]pentanedioic acid), targeting prostate specific membrane antigen (PSMA) expressed on prostate, breast, bladder and brain cancers and pteroate rhodamine B, targeting folate receptor positive cancers such as ovarian, lung, endometrium as well as inflammatory diseases have been synthesized. In vitro studies using LNCaP (PSMA +ve), PC-3 (PSMA −ve, FR −ve) and CHO-β (FR +ve) cell lines and their respective competition experiments demonstrate the specificity of the newly synthesized bioconstructs for future application in fluorescent guided intra-operative imaging.

Cross-talk between ovarian cancer cells and macrophages through periostin promotes macrophage recruitment

Tumor‐associated macrophages (TAMs) contribute to tumor progression, but it is not clear how they are recruited to tumor sites. Here we showed that periostin (POSTN) was present at high levels in ovarian cancer ascetic fluids and was correlated with CD163⁺TAMs. The high POSTN level and macrophage infiltration were inversely associated with relapse‐free survival for ovarian cancer patients. In vitro studies showed that coculture with macrophages significantly increased POSTN production in ovarian cancer cells. Further investigation found that POSTN production in ovarian cancer cells was promoted by transforming growth factor‐β generated by macrophages. Moreover, siRNA of POSTN and POSTN neutralizing antibody treatment showed that ovarian cancer cell‐derived POSTN promoted the recruitment of macrophages and modulated their cytokine secretion profile. Collectively, these data indicated that POSTN was an important factor for macrophage recruitment in the tumor microenvironment and is involved in the interactions between macrophages and ovarian cancer cells.

Imaging of Folate Receptor Expressing Macrophages in the Rat Groove Model of Osteoarthritis: Using a New DOTA-Folate Conjugate

Objective To evaluate the presence and localization of folate receptor expressing macrophages in the rat groove model of osteoarthritis and determine the suitability of a new folate conjugate with albumin-binding entity (cm09) for in vivo SPECT (single-photon emission computed tomography) analysis. Design In male Wistar rats, local cartilage damage was induced in addition to a standard ( n = 10) or high-fat diet ( n = 6). After 12 weeks, ¹¹¹In labeled folate conjugates were administered, and SPECT/CT (computed tomography) imaging was performed after 24 hours. Subsequently, osteoarthritis severity and folate receptor expression were assessed using (immuno)-histological sections. Results In vivo SPECT/CT imaging of the new folate conjugate (cm09) was as useful as a folate conjugate without albumin-binding entity in the groove model of osteoarthritis with less renal accumulation. Induction of cartilage damage on a standard diet resulted in no effect on the amount of folate receptor expressing macrophages compared with the contralateral sham operated joints. In contrast, inducing cartilage damage in the high-fat diet group resulted in 28.4% increase of folate receptor expression as compared with the nondamaged control joints. Folate receptor expressing cells were predominantly present in the synovial lining and in subchondral bone as confirmed by immunohistochemistry. Conclusions Folate receptor expression, and thus macrophage activation, can clearly be demonstrated in vivo, in small animal models of osteoarthritis using the new ¹¹¹In-folate conjugate with specific binding to the folate receptor. Increased macrophage activity only plays a role in the groove model of osteoarthritis when applied in a high-fat diet induced dysmetabolic condition, which is in line with the higher inflammatory state of that specific model.

H2O2-Depleting and O2-Generating Selenium Nanoparticles for Fluorescence Imaging and Photodynamic Treatment of Proinflammatory-Activated Macrophages

Macrophages have a pivotal role in chronic inflammatory diseases (CIDs), so imaging and controlling activated macrophage is critical for detecting and reducing chronic inflammation. In this study, photodynamic selenium nanoparticles (SeNPs) with photosensitive and macrophage-targeting bilayers were developed. The first layer of the photosensitive macromolecule was composed of a conjugate of a photosensitizer (rose bengal, RB) and a thiolated chitosan (chitosan-glutathione), resulting in a plasmonic coupling-induced red shift and broadening of RB absorption bands with increased absorption intensity. Electron paramagnetic resonance (EPR) and diphenylanthracene (DPA) quenching studies revealed that the SeNPs that were coated with the photosensitive layer were more effective than RB alone in producing singlet oxygen (¹O₂) under photoirradiation. The second layer of the activated macrophage-targetable macromolecule was synthesized by conjugation of hyaluronic acid with folic acid using an ethylenediamine linker. Proinflammatory-activated macrophages rapidly internalized the SeNPs that were covered with the targeting ligand, exhibiting a much stronger fluorescence signal of the SeNPs than did the nonactivated macrophages. Since proinflammatory-activated macrophage was known to generate a substantial amount of H₂O₂ while the inflamed site generally caused inflammation-associated tissue hypoxia, the SeNPs were further modified with O₂ self-sufficient function for photodynamic therapy. Catalase was immobilized on the SeNPs by the formation of disulfide bonds. Intracellular reduction of disulfide bonds induced the subsequent release of catalase, which catalyzed the decomposition of H₂O₂. The H₂O₂-depleting and O₂-generating photodynamic SeNPs efficiently killed activated macrophages and quenched the intracellular H₂O₂ and NO that are associated with inflammation. The SeNPs may have potential as a theranostic nanomaterial to image and control the activation of macrophages.

Distribution of Matrix Metalloproteinases in Human Atherosclerotic Carotid Plaques and Their Production by Smooth Muscle Cells and Macrophage Subsets

Purpose

In this study, the potential of matrix metalloproteinase (MMP) sense for detection of atherosclerotic plaque instability was explored. Secondly, expression of MMPs by macrophage subtypes and smooth muscle cells (SMCs) was investigated.

Procedures

Twenty-three consecutive plaques removed during carotid endarterectomy were incubated in MMPSense™ 680 and imaged with IVIS® Spectrum. mRNA levels of MMPs, macrophage markers, and SMCs were determined in plaque specimens, and in in vitro differentiated M1 and M2 macrophages.

Results

There was a significant difference between autofluorescence signals and MMPSense signals, both on the intraluminal and extraluminal sides of plaques. MMP-9 and CD68 messenger RNA (mRNA) expression was higher in hot spots, whereas MMP-2 and αSMA expression was higher in cold spots. In vitro M2 macrophages had higher mRNA expression of MMP-1, MMP-9, MMP-12, and TIMP-1 compared to M1 macrophages.

Conclusion

MMP-9 is most dominantly MMP present in atherosclerotic plaques and is produced by M2 rather than M1 macrophages.

High mobility group box 1 skews macrophage polarization and negatively influences phagocytosis of apoptotic cells

OBJECTIVES

Decreased phagocytosis of apoptotic cells plays an important role in the pathogenesis of SLE. This can lead to secondary necrosis and release of nuclear proteins, such as high mobility group box 1 (HMGB1). We hypothesized that increased HMGB1 levels, as present in SLE, skew macrophage differentiation towards M1-like phenotypes and thereby diminish uptake of apoptotic cells. The aim of this study was to investigate the effect of HMGB1 on macrophage polarization and on phagocytic capacity of differentiated macrophages.

METHODS

SLE patients with quiescent disease (SLEDAI ⩽4) and healthy controls (HCs) were included. Monocytes and differentiated M1 and M2 macrophages were assessed for expression of M1 and M2 markers and for phagocytic capacity. HMGB1 was added during differentiation and during phagocytosis.

RESULTS

Expression of CD86 (M1) was not different, whereas CD163 (M2) was significantly lower on SLE monocytes. After differentiation, no differences regarding surface receptor expression and phagocytic capacity were observed between M1 and M2 macrophages from SLE patients and HCs. Addition of HMGB1 during M2 differentiation resulted in high IL-6 and TNF-α mRNA expression and reduced phagocytic capacity of apoptotic cells. Furthermore, adding HMGB1 to apoptotic Jurkat cells diminished phagocytosis of these cells.

CONCLUSION

Circulating monocytes from SLE patients display an M1-like phenotype compared with HCs, but in vitro differentiation abolishes this difference. HMGB1 skews differentiation of M2-like macrophages towards an M1-like phenotype and, subsequently, reduces phagocytosis of apoptotic cells. These data imply that the phenotype of monocytes or macrophages is determined by their environment, such as the presence of cytokines and HMGB1.

Expression of folate receptors alpha and beta in normal and cancerous gynecologic tissues: correlation of expression of the beta isoform with macrophage markers

Background

Folate receptor alpha (FOLR1/FRA) is expressed in a number of epithelial cancers and in particular epithelial ovarian cancer (EOC), especially of the serous histotype. Recent studies have shown that EOC originates from the fallopian tube fimbriae rather than from epithelial cells lining the ovary. We have previously shown by immunohistochemistry a strong correlation between FRA expression in EOC and normal and fallopian adenocarcinoma. Folate receptor beta (FOLR2/FRB) has been described to be expressed by macrophages both in inflammatory disorders and certain epithelial cancers. Given the high sequence identity of these two folate receptor family members we sought to investigate the architectural and cell-specific expression of these two receptors in gynecologic tissues.

Methods

RNA scope, a novel chromogenic in situ hybridization assay tool, was used to examine expression of the alpha (FOLR1) and beta (FOLR2) isoforms of folate receptor relative to each other as well as to the macrophage markers CD11b and CD68, in samples of normal fallopian tube and fallopian adenocarcinoma as well as normal ovary and EOC.

Results

We demonstrated expression of both FOLR1 and FOLR2 in EOC, normal fallopian tube and fallopian adenocarcinoma tissue while very little expression of either marker was observed in normal ovary. Furthermore, FOLR2 was shown to be expressed almost exclusively in macrophages, of both the M1 and M2 lineages, as determined by co-expression of CD11b and/or CD68, with little or no expression in epithelial cells.

Conclusions

These findings further substantiate the hypothesis that the cell of origin of EOC is tubal epithelium and that the beta isoform of folate receptor is primarily restricted to macrophages. Further, macrophages expressing FOLR2 may represent tumor associated or infiltrating macrophages (TAMs) in epithelial cancers.

Folate receptor–targeted single-photon emission computed tomography/computed tomography to detect activated macrophages in atherosclerosis: can it distinguish vulnerable from stable atherosclerotic plaques?

The need for noninvasive imaging to distinguish stable from vulnerable atherosclerotic plaques is evident. Activated macrophages play a role in atherosclerosis and express folate receptor folate receptor β (FR-β). The feasibility of folate targeting to detect atherosclerosis was demonstrated in human and mouse plaques, and it was suggested that molecular imaging of FR-β through folate conjugates might be a specific marker for plaque vulnerability. However, these studies did not allow differentiation between stable and vulnerable atherosclerotic plaques. We investigated the feasibility of a folate-based radiopharmaceutical (111)In-EC0800) with high-resolution animal single-photon emission computed tomography/computed tomography (SPECT/CT) to differentiate between stable and vulnerable atherosclerotic plaques in apolipoprotein E(−/−) mice in which we can induce plaques with the characteristics of stable and vulnerable plaques by placing a flow-modifying cast around the common carotid artery. Both plaques showed (111)In-EC0800 uptake, with higher uptake in the vulnerable plaque. However, the vulnerable plaque was larger than the stable plaque. Therefore, we determined tracer uptake per plaque volume and demonstrated higher accumulation of (111)In-EC0800 in the stable plaque normalized to plaque volume. Our data show that (111)In-EC0800 is not a clear-cut marker for the detection of vulnerable plaques but detects both stable and vulnerable atherosclerotic plaques in a mouse model of atherosclerosis.

Identification of genes whose expression is altered by obesity throughout the arterial tree

We used next-generation RNA sequencing (RNA-Seq) technology on the whole transcriptome to identify genes whose expression is consistently affected by obesity across multiple arteries. Specifically, we examined transcriptional profiles of the iliac artery as well as the feed artery, first, second, and third branch order arterioles in the soleus, gastrocnemius, and diaphragm muscles from obese Otsuka Long-Evans Tokushima Fatty (OLETF) and lean Long-Evans Tokushima Otsuka (LETO) rats. Within the gastrocnemius and soleus muscles, the number of genes differentially expressed with obesity tended to increase with increasing branch order arteriole number (i.e., decreasing size of the artery). This trend was opposite in the diaphragm. We found a total of 15 genes that were consistently upregulated with obesity (MIS18A, CTRB1, FAM151B, FOLR2, PXMP4, OAS1B, SREBF2, KLRA17, SLC25A44, SNX10, SLFN3, MEF2BNB, IRF7, RAD23A, LGALS3BP) and five genes that were consistently downregulated with obesity (C2, GOLGA7, RIN3, PCP4, CYP2E1). A small fraction (∼9%) of the genes affected by obesity was modulated across all arteries examined. In conclusion, the present study identifies a select number of genes (i.e., 20 genes) whose expression is consistently altered throughout the arterial network in response to obesity and provides further insight into the heterogeneous vascular effects of obesity. Although there is no known direct function of the majority of 20 genes related to vascular health, the obesity-associated upregulation of SREBF2, LGALS3BP, IRF7, and FOLR2 across all arteries is suggestive of an unfavorable vascular phenotypic alteration with obesity. These data may serve as an important resource for identifying novel therapeutic targets against obesity-related vascular complications.

Anti-Saccharomyces cerevisiae autoantibodies in autoimmune diseases: from bread baking to autoimmunity

Saccharomyces cerevisiae is best known as the baker's and brewer's yeast, but its residual traces are also frequent excipients in some vaccines. Although anti-S. cerevisiae autoantibodies (ASCAs) are considered specific for Crohn's disease, a growing number of studies have detected high levels of ASCAs in patients affected with autoimmune diseases as compared with healthy controls, including antiphospholipid syndrome, systemic lupus erythematosus, type 1 diabetes mellitus, and rheumatoid arthritis. Commensal microorganisms such as Saccharomyces are required for nutrition, proper development of Peyer's aggregated lymphoid tissue, and tissue healing. However, even the commensal nonclassically pathogenic microbiota can trigger autoimmunity when fine regulation of immune tolerance does not work properly. For our purposes, the protein database of the National Center for Biotechnology Information (NCBI) was consulted, comparing Saccharomyces mannan to several molecules with a pathogenetic role in autoimmune diseases. Thanks to the NCBI bioinformation technology tool, several overlaps in molecular structures (50-100 %) were identified when yeast mannan, and the most common autoantigens were compared. The autoantigen U2 snRNP B″ was found to conserve a superfamily protein domain that shares 83 % of the S. cerevisiae mannan sequence. Furthermore, ASCAs may be present years before the diagnosis of some associated autoimmune diseases as they were retrospectively found in the preserved blood samples of soldiers who became affected by Crohn's disease years later. Our results strongly suggest that ASCAs' role in clinical practice should be better addressed in order to evaluate their predictive or prognostic relevance.

Folate receptor-targeted aminopterin therapy is highly effective and specific in experimental models of autoimmune uveitis and autoimmune encephalomyelitis

EC0746 is a rationally designed anti-inflammatory drug conjugate consisting of a modified folic acid-based ligand linked to a γ-hydrazide analog of aminopterin. In this report, EC0746's effectiveness was evaluated against experimental retinal S-antigen (PDSAg) induced autoimmune uveitis (EAU) and myelin-basic-protein induced autoimmune encephalomyelitis (EAE). In both models, functional FR-β was detected on activated macrophages in local (retinal or central-nervous-system, respectively) and systemic (peritoneal cavity) sites of inflammation. In myelin-rich regions of EAE rats, an increased uptake of (99m)Tc-EC20 (etarfolatide; a FR-specific radioimaging agent) was also observed. EC0746 treatment at disease onset suppressed the clinical severity of both EAU and EAE, and it strongly attenuated progressive histopathological changes in the affected organs. In all parameters assessed, EC0746 activity was completely blocked by a benign folate competitor, suggesting that these therapeutic outcomes were specifically FR-β mediated. EC0746 may emerge as a useful macrophage-modulating agent for treating inflammatory episodes of organ-specific autoimmunity.

Articular adipose tissue resident macrophages in rheumatoid arthritis patients: potential contribution to local abnormalities

OBJECTIVES

The objectives of this study were to characterize macrophages resident in inflamed articular adipose tissue (AAT) and non-inflamed subcutaneous adipose tissue (ScAT) of RA patients and to evaluate the basal and cytokine-triggered secretory activities of these tissues.

METHODS

Tissues were obtained from patients undergoing knee joint replacement surgery. The number of total CD68(+), CD14(+) and CD163(+) macrophages was evaluated by immunohistochemistry. The concentrations of select factors were measured in supernatants from untreated and cytokine-treated tissue explant cultures using ELISA. IL-1β and TNF were applied as the stimuli.

RESULTS

Paired samples of AAT and ScAT, obtained from the same patients, contained a similar number of macrophages, displaying an M2-skewed phenotype. Both tissues released equivalent amounts of IL-1β, TNF, IL-10 and macrophage migration inhibitory factor (MIF). However, AAT secreted more chemokines (CCL2, CCL5), cytokines [IL-6, IL-8, IL-1 receptor antagonist (IL-1Ra)], hepatocyte growth factor (HGF) and MMP-3 than ScAT. Basal secretion of adipocytokines was not patient specific. Except for HGF and MIF, cytokine treatment up-regulated the release of these factors from both tissues, but also upon stimulation AAT produced more IL-6, IL-8 and IL-1Ra than ScAT.

CONCLUSION

The secretory activity, reflecting cell activation status but not phenotype or the number of macrophages, discriminates rheumatoid AAT from ScAT. By releasing various factors possessing chemotactic, proinflammatory, anti-inflammatory and tissue degrading activities, AAT resident macrophages may drive and control local pathological processes.

Targeting of tumor-associated macrophages made possible by PEG-sheddable, mannose-modified nanoparticles

It is increasingly evident that tumor-associated macrophages (TAMs) play an important role in tumor invasion, proliferation, and metastasis. While delivery of drugs, imaging agents, and vaccines to TAMs was achieved by exploiting membrane receptors on TAMs, the uptake by normal macrophages remains an issue. In this communication, we report a PEG-sheddable, mannose-modified nanoparticle platform that can efficiently target TAMs via mannose-mannose receptor recognition after acid-sensitive PEG shedding in the acidic tumor microenvironment, while their uptake by normal macrophages in the mononuclear phagocyte system (MPS) organs was significantly reduced due to effective PEG shielding at neutral pH. These nanoparticles have the potential to target drugs of interest to TAMs, with decreased uptake by normal macrophages.

Receptor-based targeting of therapeutics

Receptor-based targeting of therapeutics may be a fascinating proposition to improve the therapeutic efficacy of encapsulated drugs. The development of safe and effective nanomedicines is a prerequisite in the current nanotechnological scenario. Currently, the surface engineering of nanocarriers has attracted great attention for targeted therapeutic delivery by selective binding of targeting ligand to the specific receptors present on the surface of cells. In this review, we have discussed the current status of various receptors such as transferrin, lectoferrin, lectin, folate, human EGF receptor, scavenger, nuclear and integrin, which are over-expressed on the surface of cancer cells; along with the relevance of targeted delivery systems such as nanoparticles, polymersomes, dendrimers, liposomes and carbon nanotubes. The review also focuses on the effective utilization of receptor-based targeted delivery systems for the management of cancer in effective ways by minimizing the drug-associated side effects and improving the therapeutic efficacy of developed nano-architectures.

Evaluation of the novel folate receptor ligand [18F]fluoro-PEG-folate for macrophage targeting in a rat model of arthritis

INTRODUCTION

Detection of (subclinical) synovitis is relevant for both early diagnosis and monitoring of therapy of rheumatoid arthritis (RA). Previously, the potential of imaging (sub)clinical arthritis was demonstrated by targeting the translocator protein in activated macrophages using (R)-[11C]PK11195 and positron emission tomography (PET). Images, however, also showed significant peri-articular background activity. The folate receptor (FR)-β is a potential alternative target for imaging activated macrophages. Therefore, the PET tracer [18F]fluoro-PEG-folate was synthesized and evaluated in both in vitro and ex vivo studies using a methylated BSA induced arthritis model.

METHODS

[18F]fluoro-PEG-folate was synthesized in a two-step procedure. Relative binding affinities of non-radioactive fluoro-PEG-folate, folic acid and naturally circulating 5-methyltetrahydrofolate (5-Me-THF) to FR were determined using KB cells with high expression of FR. Both in vivo [18F]fluoro-PEG-folate PET and ex vivo tissue distribution studies were performed in arthritic and normal rats and results were compared with those of the established macrophage tracer (R)-[11C]PK11195.

RESULTS

[18F]fluoro-PEG-folate was synthesized with a purity >97%, a yield of 300 to 1,700 MBq and a specific activity between 40 and 70 GBq/µmol. Relative in vitro binding affinity for FR of F-PEG-folate was 1.8-fold lower than that of folic acid, but 3-fold higher than that of 5-Me-THF. In the rat model, [18F]fluoro-PEG-folate uptake in arthritic knees was increased compared with both contralateral knees and knees of normal rats. Uptake in arthritic knees could be blocked by an excess of glucosamine-folate, consistent with [18F]fluoro-PEG-folate being specifically bound to FR. Arthritic knee-to-bone and arthritic knee-to-blood ratios of [18F]fluoro-PEG-folate were increased compared with those of (R)-[11C]PK11195. Reduction of 5-Me-THF levels in rat plasma to those mimicking human levels increased absolute [18F]fluoro-PEG-folate uptake in arthritic joints, but without improving target-to-background ratios.

CONCLUSIONS

The novel PET tracer [18F]fluoro-PEG-folate, designed to target FR on activated macrophages provided improved contrast in a rat model of arthritis compared with the accepted macrophage tracer (R)-[11C]PK11195. These results warrant further exploration of [18F]fluoro-PEG-folate as a putative PET tracer for imaging (sub)clinical arthritis in RA patients.