Macrophage specificity of three anti-CD68 monoclonal antibodies (KP1, EBM11, and PGM1) widely used for immunohistochemistry and flow cytometry

Modelling the Sorafenib-resistant Liver Cancer Microenvironment by Using 3-D Spheroids

Liver cancer is the third leading cause of cancer-related mortality, and hepatocellular carcinoma (HCC) is the most common form of liver cancer, and it usually occurs in the setting of chronic liver disease and cirrhosis. For patients with advanced HCC, systemic treatment is the first choice - however, resistance occurs frequently. Sorafenib was the first tyrosine kinase inhibitor approved for advanced HCC, and resistance to the therapy is a serious concern. When sorafenib therapy fails in a patient, it can be challenging to decide whether they can undergo a second-line therapy, and to determine which therapy they will be able to tolerate. Thus, physiologically relevant in vitro preclinical models are crucial for screening potential therapies, and 3-D tumour spheroids permit studies of tumour pathobiology. In this study, a drug-resistant 3-D tumour spheroid model was developed, based on sorafenib-resistant hepatocellular carcinoma cells, LX2 stellate cells and THP-1 monocytes. Model tumour spheroids that were formed with the sorafenib-resistant cells demonstrated lower diffusion of doxorubicin and exhibited increased resistance to regorafenib. Moreover, in the sorafenib-resistant spheroids, there was increased presence of CD68-positive cells and a reduction in inflammatory marker secretion. The sorafenib-resistant cell line-derived spheroids also showed a higher expression of FGF-19, PDGF-AA and GDF-15, which are known to be involved in malignancies. This multi-cell type spheroid model represents a potentially useful system to test drug candidates in a microenvironment that mimics the drug-resistant tumour microenvironment in HCC.

Skewing cPLA2α activity toward oxoeicosanoid production promotes neutrophil N2 polarization, wound healing, and the response to sepsis

Uncontrolled inflammation is linked to poor outcomes in sepsis and wound healing, both of which proceed through distinct inflammatory and resolution phases. Eicosanoids are a class of bioactive lipids that recruit neutrophils and other innate immune cells. The interaction of ceramide 1-phosphate (C1P) with the eicosanoid biosynthetic enzyme cytosolic phospholipase A2 (cPLA2) reduces the production of a subtype of eicosanoids called oxoeicosanoids. We investigated the effect of shifting the balance in eicosanoid biosynthesis on neutrophil polarization and function. Knockin mice expressing a cPLA2 mutant lacking the C1P binding site (cPLA2αKI/KI mice) showed enhanced and sustained neutrophil infiltration into wounds and the peritoneum during the inflammatory phase of wound healing and sepsis, respectively. The mice exhibited improved wound healing and reduced susceptibility to sepsis, which was associated with an increase in anti-inflammatory N2-type neutrophils demonstrating proresolution behaviors and a decrease in proinflammatory N1-type neutrophils. The N2 polarization of cPLA2αKI/KI neutrophils resulted from increased oxoeicosanoid biosynthesis and autocrine signaling through the oxoeicosanoid receptor OXER1 and partially depended on OXER1-dependent inhibition of the pentose phosphate pathway (PPP). Thus, C1P binding to cPLA2α suppresses neutrophil N2 polarization, thereby impairing wound healing and the response to sepsis.

The Mac Is Back: The Role of Macrophages in Human Healthy and Complicated Pregnancies

Pregnancy is a fascinating immunological paradox: the semi-allogeneic fetus generally grows without any complications. In the placenta, fetal trophoblast cells come into contact with maternal immune cells. Inaccurate or inadequate adaptations of the maternal immune system could lead to problems with the functioning of the placenta. Macrophages are important for tissue homeostasis, cleanup, and the repair of damaged tissues. This is crucial for a rapidly developing organ such as the placenta. The consensus on macrophages at the maternal-fetal interface in pregnancy is that a major proportion have an anti-inflammatory, M2-like phenotype, that expresses scavenger receptors and is involved in tissue remodeling and the dampening of the immune reactions. Recent multidimensional analyses have contributed to a more detailed outlook on macrophages. The new view is that this lineage represents a highly diverse phenotype and is more prevalent than previously thought. Spatial-temporal in situ analyses during gestation have identified unique interactions of macrophages both with trophoblasts and with T cells at different trimesters of pregnancy. Here, we elaborate on the role of macrophages during early human pregnancy and at later gestation. Their possible effect is reviewed in the context of HLA incompatibility between mother and fetus, first in naturally conceived pregnancies, but foremost in pregnancies after oocyte donation. The potential functional consequences of macrophages for pregnancy-related immune reactions and the outcome in patients with recurrent pregnancy loss are also discussed.

The Alteration of T-Cell Heterogeneity and PD-L1 Colocalization During dMMR Colorectal Cancer Progression Defined by Multiplex Immunohistochemistry

Background

Immune checkpoint inhibitors (ICIs) are quickly becoming key instruments in the treatment of mismatch repair-deficient (dMMR) colorectal cancers (CRCs). Despite their clinical value, ICIs have several limitations associated with their use. Only approximately 15% of all CRCs have a dMMR status, and the overall response rate of ICIs is approximately 40%. The mechanism of ICI resistance is not clear, and its study is limited by the lack of information available on the characterization of the immune microenvironment during the progression from early- to advanced-stage dMMR CRC.

Methods

We used multiplex immunohistochemistry (mIHC) with two panels, each containing five markers, to simultaneously analyze the proportions of immune microenvironment constituents in 59 patients with advanced-stage dMMR CRC and 24 patients with early-stage dMMR CRC. We detected immune cell–associated signatures in the epithelial and stromal regions and evaluated the predictive value of these immune molecules. Student’s t-tests, Mann–Whitney U tests, Cox proportional hazards regression modeling, univariate Cox modeling, and Kaplan–Meier estimation were used to analyze immune cell proportions and survival data.

Results

We observed significantly higher proportions of CD8+ cytotoxic T cells (CD8+) (p = 0.001), CD8+ memory T cells (CD8+CD45RO+) (p = 0.032), and CD4+ regulatory T cells (CD4+FOXP3+) (p = 0.011) in the advanced-stage dMMR CRCs than in the early-stage dMMR CRCs. Furthermore, CD3+ T cells with PD-L1 colocalization (CD3+PD-L1+) (p = 0.043) and CD8+ T cells with PD-L1 colocalization (CD8+PD-L1+) (p = 0.005) were consistently more numerous in patients in the advanced stage than those in the early stage. Our analyses revealed that a high proportion of CD3+PD-1+ T cells was an independent prognostic factor of overall survival (OS) [hazard ratios (HR) = 9.6, p < 0.001] and disease-free survival (DFS) (HR = 3.7, p = 0.010) in patients in the advanced stage.

Conclusion

High numbers of CD8+ cytotoxic T cells and CD8+ memory T cells, which usually represent a cytotoxic function of the adaptive immune system and possibly enhanced inhibition factors, such as CD4+ regulatory T cells and PD-L1 colocalized T cells, were associated with the transformation of the immune microenvironment from the early stage to the advanced stage in dMMR CRCs. Furthermore, CD3+PD-1+ T cells are a prognostic factor for patients with dMMR.

LA-ICP-MS and Immunohistochemical Staining with Lanthanide-Labeled Antibodies to Study the Uptake of CeO2 Nanoparticles by Macrophages in Tissue Sections

Due to the increasing use and production of CeO₂ nanoparticles (NPs), the likelihood of exposure especially via the air rapidly grows. However, the uptake of CeO₂ NPs via the lung and the resulting distribution into various cell types of remote organs are not well understood because classical analytical methods provide limited spatial information. In this study, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was combined with immunohistochemical (IHC) staining with lanthanide-labeled antibodies to investigate the distribution of intratracheally instilled CeO₂ NPs from the rat lung to lymph nodes, spleen, and liver after 3 h, 3 days, and 21 days. We selected regions of interest after fast imaging using LA-ICP-MS in low-resolution mode and conducted high-resolution LA-ICP-MS in combination with IHC for cellular localization. The lanthanide labeling, which was largely congruent with conventional fluorescent labeling, allowed us to calculate the association rates of Ce to specific cell types. Major portions of Ce were found to be associated with phagocytic cells in the lung, lymph nodes, spleen, and liver. In the lung, almost 94% of the Ce was co-localized with CD68-positive alveolar macrophages after 21 days. Ce was also detected in the lymph nodes outside macrophages 3 h post instillation but shifted to macrophage-associated locations. In the liver, Ce accumulations associated with Kupffer cells (CD163-positive) were found. Ce-containing populations of metallophilic and marginal zone macrophages (both CD169-positive) as well as red pulp macrophages (CD68-positive) were identified as major targets in the spleen. Overall, high-resolution LA-ICP-MS analysis in combination with IHC staining with lanthanide-labeled antibodies is a suitable tool to quantify and localize Ce associated with specific cell types and to estimate their particle burden under in vivo conditions.

Advances in Visualizing Microglial Cells in Human Central Nervous System Tissue

Neuroinflammation has recently been identified as a fundamentally important pathological process in most, if not all, CNS diseases. The main contributor to neuroinflammation is the microglia, which constitute the innate immune response system. Accurate identification of microglia and their reactivity state is therefore essential to further our understanding of CNS pathophysiology. Many staining techniques have been used to visualise microglia in rodent and human tissue, and immunostaining is currently the most frequently used. Historically, identification of microglia was predominantly based on morphological structure, however, recently there has been a reliance on selective antigen expression, and microglia-specific markers have been identified providing increased certainty that the cells observed are in fact microglia, rather than the similar yet distinct macrophages. To date, the most microglia-specific markers are P2Y12 and TMEM119. However, other microglia-related markers can also be useful for demonstrating activation state, phagocytic state, and for neuroimaging purposes in longitudinal studies. Overall, it is important to be aware of the microglia-selectivity issues of the various stains and immunomarkers used by researchers to distinguish microglia in CNS tissue to avoid misinterpretation.

Single-Cell RNA Sequencing of Human Pluripotent Stem Cell-Derived Macrophages for Quality Control of The Cell Therapy Product

Macrophages exhibit high plasticity to achieve their roles in maintaining tissue homeostasis, innate immunity, tissue repair and regeneration. Therefore, macrophages are being evaluated for cell-based therapeutics against inflammatory disorders and cancer. To overcome the limitation related to expansion of primary macrophages and cell numbers, human pluripotent stem cell (hPSC)-derived macrophages are considered as an alternative source of primary macrophages for clinical application. However, the quality of hPSC-derived macrophages with respect to the biological homogeneity remains still unclear. We previously reported a technique to produce hPSC-derived macrophages referred to as iMACs, which is amenable for scale-up. In this study, we have evaluated the biological homogeneity of the iMACs using a transcriptome dataset of 6,230 iMACs obtained by single-cell RNA sequencing. The dataset provides a valuable genomic profile for understanding the molecular characteristics of hPSC-derived macrophage cells and provide a measurement of transcriptomic homogeneity. Our study highlights the usefulness of single cell RNA-seq data in quality control of the cell-based therapy products.

Accuracy of fine-needle aspiration of lymph nodes: A cancer center's experience

INTRODUCTION

Lymph node fine needle aspiration (LN-FNA) is a minimally invasive method of evaluating lymphadenopathy. Nonetheless, its use is not widely accepted due to the lack of guidelines and a cytopathological categorisation that directly relates to management. We report our experience with LN FNA at a large Cancer Center in Latin America.

METHODS

We retrospectively collected cytological cases of lymph node FNA from the department of pathology at AC Camargo Cancer Center performed over a 2-year period. Data extracted included LN location, age, sex and final cytological diagnosis. Patients that had undergone neoadjuvant chemotherapy and/or cases for which the surgery specimen location was not clearly reported were excluded. For those cases with surgical reports, risk of malignancy was calculated for each diagnostic category, along with overall performance of cytology. False positive cases were reviewed to assess any possible misinterpretation or sampling errors.

RESULTS

A total of 1730 LN-FNA were distributed as follows: 62 (3.5%) non-diagnostic (ND); 1123 (64.9%) negative (NEG), 19 (1.1%) atypical (ATY), 53 (3.1%) suspicious for malignancy (SUS), and 473 (27.3%) positive (POS). Surgical reports were available for 560 cases (32.4%). Risk of malignancy (ROM) for each category was 33.3% for ND, 29.9% for NEG, 25% for ATY, 74.2% for SUS and 99.6% for POS. Overall sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were 78.5%, 99.4%, 70.2% and 99.6%, respectively.

CONCLUSION

Lymph node FNA is a very specific and accurate exam, which is reliable in the detection of lymph node metastasis and other causes of lymphadenopathy.

Macrophage-Mediated Tissue Vascularization: Similarities and Differences Between Cornea and Skin

Macrophages are critical mediators of tissue vascularization both in health and disease. In multiple tissues, macrophages have been identified as important regulators of both blood and lymphatic vessel growth, specifically following tissue injury and in pathological inflammatory responses. In development, macrophages have also been implicated in limiting vascular growth. Hence, macrophages provide an important therapeutic target to modulate tissue vascularization in the clinic. However, the molecular mechanisms how macrophages mediate tissue vascularization are still not entirely resolved. Furthermore, mechanisms might also vary among different tissues. Here we review the role of macrophages in tissue vascularization with a focus on their role in blood and lymphatic vessel formation in the barrier tissues cornea and skin. Comparing mechanisms of macrophage-mediated hem- and lymphangiogenesis in the angiogenically privileged cornea and the physiologically vascularized skin provides an opportunity to highlight similarities but also tissue-specific differences, and to understand how macrophage-mediated hem- and lymphangiogenesis can be exploited for the treatment of disease, including corneal wound healing after injury, graft rejection after corneal transplantation or pathological vascularization of the skin.

Myeloid sarcoma, chloroma, or extramedullary acute myeloid leukemia tumor: A tale of misnomers, controversy and the unresolved

The World Health Organization classification and definition of "myeloid sarcoma" is imprecise and misleading. A more accurate term is "extramedullary acute myeloid leukemia tumor (eAML)." The pathogenesis of eAML has been associated with aberrancy of cellular adhesion molecules, chemokine receptors/ligands and RAS-MAPK/ERK signaling. eAML can present with or without synchronous or metachronous intramedullary acute myeloid leukemia (AML) so a bone marrow evaluation is always recommended. Accurate diagnosis of eAML requires tissue biopsy. eAML confined to one or a few sites is frequently treated with local therapy such as radiotherapy. About 75-90% of patients with isolated eAML will develop metachronous intramedullary AML with a median latency period ranging from 4 to 12 months; thus, patients with isolated eAML may also be treated with systemic anti-leukemia therapy. eAML does not appear to have an independent prognostic impact; selection of post-remission therapy including allogeneic hematopoietic cell transplant (alloHCT) is typically guided by intramedullary disease risk. Management of isolated eAML should be individualized based on patient characteristics as well as eAML location and cytogenetic/molecular features. The role of PET/CT in eAML is also currently being elucidated. Improving outcomes of patients with eAML requires further knowledge of its etiology and mechanism(s) as well as therapeutic approaches beyond conventional chemotherapy, ideally in the context of controlled trials.

Ex vivo MR microscopy of a human brain with multiple sclerosis: Visualizing individual cells in tissue using intrinsic iron

Purpose:

To perform magnetic resonance microscopy (MRM) on human cortex and a cortical lesion as well as the adjacent normal appearing white matter. To shed light on the origins of MRI contrast by comparison with histochemical and immunostaining.

Methods:

3D MRM at a nominal isotropic resolution of 15 and 18 μm was performed on 2 blocks of tissue from the brain of a 77-year-old man who had MS for 47 years. One block contained normal appearing cortical gray matter (CN block) and adjacent normal appearing white matter (NAWM), and the other also included a cortical lesion (CL block). Postmortem ex-vivo MRI was performed at 11.7T using a custom solenoid coil and T₂*-weighted 3D GRE sequence. Histochemical and immunostaining were done after paraffin embedding for iron, myelin, oligodendrocytes, neurons, blood vessels, macrophages and microglia, and astrocytes.

Results:

MRM could identify individual iron-laden oligodendrocytes with high sensitivity (70% decrease in signal compared to surrounding) in CN and CL blocks, as well as some iron-laden activated macrophages and microglia. Iron-deficient oligodendrocytes seemed to cause relative increase in MRI signal within the cortical lesion. High concentration of myelin in the white matter was primarily responsible for its hypointense appearance relative to the cortex, however, signal variations within NAWM could be attributed to changes in density of iron-laden oligodendrocytes.

Conclusion:

Changes in iron accumulation within cells gave rise to imaging contrast seen between cortical lesions and normal cortex, as well as the patchy signal in NAWM. Densely packed myelin and collagen deposition also contributed to MRM signal changes. Even though we studied only one block each from normal appearing and cortical lesions, such studies can help better understand the origins of histopathological and microstructural correlates of MRI signal changes in multiple sclerosis and contextualize the interpretation of lower-resolution in vivo MRI scans.

The peridural membrane of the spine has characteristics of synovium

The peridural membrane (PDM) is a well-defined structure between dura mater and the wall of the spinal canal. The spine may be viewed as a multi-segmented joint, with the epidural cavity and neural foramina as joint spaces and PDM as synovial lining. The objective of this investigation was to determine if PDM has histological characteristics of synovium. Samples of the PDM of the thoraco-lumbar spine were taken from 23 human cadavers and analyzed with conventional light microscopy and confocal microscopy. Results were compared to reports on similar analyses of synovium in the literature. Histological distribution of areolar, fibrous, and adipose connective tissue in PDM was similar to synovium. The PDM has an intima and sub-intima. No basement membrane was identified. CD68, a marker for macrophage-like-synoviocytes, and CD55, a marker for fibroblast-like synoviocytes, were seen in the lining and sub-lining of the PDM. Multifunctional hyaluronan receptor CD44 and hyaluronic acid synthetase 2 marker HAS2 were abundantly present throughout the membrane. Marked presence of CD44, CD55, and HAS2 in the well-developed tunica muscularis of blood vessels and in the body of the PDM suggests a role in the maintenance and lubrication of the epidural cavity and neural foramina. Presence of CD68, CD55, and CD44 suggests a scavenging function and a role in the inflammatory response to noxious stimuli. Thus, the human PDM has histological and immunohistochemical characteristics of synovium. This suggests that the PDM may be important for the homeostasis of the flexible spine and the neural structures it contains.

Alveolar macrophage dysfunction and cytokine storm in the pathogenesis of two severe COVID-19 patients

BACKGROUND

The novel coronavirus pneumonia COVID-19 caused by SARS-CoV-2 infection could lead to a series of clinical symptoms and severe illnesses, including acute respiratory distress syndrome (ARDS) and fatal organ failure. We report the fundamental pathological investigation in the lungs and other organs of fatal cases for the mechanistic understanding of severe COVID-19 and the development of specific therapy in these cases.

METHODS

The autopsy and pathological investigations of specimens were performed on bodies of two deceased cases with COVID-19. Gross anatomy and histological investigation by Hematoxylin and eosin (HE) stained were reviewed on each patient. Alcian blue/periodic acid-Schiff (AB-PAS) staining and Masson staining were performed for the examinations of mucus, fibrin and collagen fiber in lung tissues. Immunohistochemical staining was performed on the slides of lung tissues from two patients. Real-time PCR was performed to detect the infection of SARS-CoV-2. Flow cytometry analyses were performed to detect the direct binding of S protein and the expression of ACE2 on the cell surface of macrophages.

FINDINGS

The main pathological features in lungs included extensive impairment of type I alveolar epithelial cells and atypical hyperplasia of type II alveolar cells, with formation of hyaline membrane, focal hemorrhage, exudation and pulmonary edema, and pulmonary consolidation. The mucous plug with fibrinous exudate in the alveoli and the dysfunction of alveolar macrophages were characteristic abnormalities. The type II alveolar epithelial cells and macrophages in alveoli and pulmonary hilum lymphoid tissue were infected by SARS-CoV-2. S protein of SARS-CoV-2 directly bound to the macrophage via the S-protein-ACE2 interaction.

INTERPRETATION

Infection of alveolar macrophage by SARS-CoV-2 might be drivers of the "cytokine storm", which might result in damages in pulmonary tissues, heart and lung, and lead to the failure of multiple organs .

FUNDING

Shanghai Guangci Translational Medical Research Development Foundation, Shanghai, China.

CD68+ macrophages as crucial components of the foreign body reaction demonstrate an unconventional pattern of functional markers quantified by analysis with double fluorescence staining

Implants like meshes for the reinforcement of tissues implement the formation of a persistent inflammation with an ambient fibrotic reaction. In the inflammatory infiltrate several distinct cell types have been identified, but CD68+ macrophages are supposed to be most important. To investigate the collaboration among the various cell types within the infiltrate we performed at explanted meshes from humans double fluorescence staining with CD68 as a constant marker and a variety of other antibodies as the second marker. The list of second markers includes lymphocytes (CD3, CD4, CD8, CD16, CD56, FoxP3, and CD11b) stem cells (CD34), leucocytes (CD45, CD15), macrophages (CD86, CD105, CD163, and CD206); deposition of EC matrix (collagen-I, collagen-III, MMP2, and MMP8); Ki67 as a marker for proliferation; and the tyrosine-protein kinase receptor AXL. The present study demonstrates within the inflammatory infiltrate the abundant capability of CD68+ cells to co-express a huge variety of other markers, including those of lymphocytes, varying between 5 and 83% of investigated cells. The observation of co-staining was not restricted to a specific polymer but was seen with polypropylene fibers as well as with fibers made of polyvinylidene fluoride, although with differences in co-expression rates. The persisting variability of these cells without the functional reduction toward differentiated mature cell types may favor the lack of healing at the interface of meshes.

Impact of Mononuclear Cell Infiltration on Chondrodestructive MMP/ADAMTS Production in Osteoarthritic Knee Joints-An Ex Vivo Study

Progressive loss of joint function in osteoarthritis (OA) is driven by degenerative and inflammatory processes and their complex interaction. Decoding the link between degeneration and inflammation is one of the most exciting approaches in understanding OA pathophysiology and holds the promise to open new therapeutic avenues. The overarching goal of this project was to analyze the impact of mononuclear cells (MNC) on enzymatic chondrodestructive processes (MMP/ADAMTS) in OA. Synovial membrane (SM), articular cartilage (AC) and peripheral blood (PB) were obtained from a total of 21 patients with advanced knee OA who underwent arthroplastic surgery. In supernatants of native synovial cell cultures, T cell-depleted synovial cell cultures and macrophage-depleted synovial cell cultures, the concentrations of various metalloproteinases were examined by Enzyme Linked Immunosorbent Assay (ELISA). Furthermore, ELISA was used to analyze concentrations of metalloproteinases in supernatants of chondrocyte monocultures and chondrocyte co-cultures with CD4⁺CD127^dim/- enriched peripheral blood mononuclear cells (PBMC), Treg depleted CD4⁺CD25^-CD127^dim/- enriched PBMC and CD4⁺CD25⁺CD127^dim/- Treg. Compared to native synovial cell culture, T cell depletion led to significantly lower levels of MMP-1, MMP-3 and MMP-9 and macrophage depletion led to a significant decline of MMP-1, MMP-3, MMP-9 and ADAMTS-5 concentration. Compared to T cell depletion, macrophage depletion resulted in a significantly stronger reduction of MMP-1, MMP-3, MMP-9 and ADAMTS-5. In chondrocyte co-culture with CD4⁺CD127^dim/- enriched PBMC the concentration of MMP-1 and ADAMTS-5 was significantly increased compared to chondrocyte monoculture. No significant differences were found between chondrocyte monoculture and chondrocyte co-culture with Treg as well as between co-culture with CD4⁺CD127^dim/- enriched PBMC containing Treg and co-culture with Treg-depleted CD4⁺CD25^-CD127^dim/- enriched PBMC. In conclusion, our data suggests that both synovial macrophages and T cells have a catabolic potential by inducing the release of chondrodestructive metalloproteinases in OA synovium. This study also supports the hypothesis that MNC affect the release of metalloproteinases by chondrocytes and are hereby involved in the cartilage-induced chondrodestructive process. In this study no suppressive effect of Treg was shown.

Inhibition of the migration of MCP-1 positive cells by icing applied soon after crush injury to rat skeletal muscle

Migration of the macrophages to the injured site soon after the skeletal muscle injury is crucial for subsequent regeneration of the muscle fibers. The Monocyte chemoattractant protein-1 (MCP-1) is important chemokine for regulating migration of the monocytes/macrophages. Earlier reports have discussed that icing applied soon after muscle crush injury retards muscle regeneration through retardation of macrophage migration. The MCP-1+ cells and neutrophils might promote the migration of the macrophages. To test the hypothesis that icing soon after the skeletal muscle injury affects MCP-1+ cells and neutrophils, we examined the effect of icing on MCP-1+ cells and neutrophils after crush injury to skeletal muscle in rats. Owing to the icing application for 20 min soon after the injury, accumulation of the macrophages was inhibited until 12 h after injury. Numbers of the neutrophils at 3 h after the injury and the MCP-1+ cells at 6 h and later after the injury in the icing group were significantly lower than those in the non-icing group, suggesting that these phenomena contribute to the retardation of macrophage migration.

Cutaneous metaplastic synovial cyst in Ehlers-Danlos syndrome

Classic Ehlers-Danlos syndrome (EDS) is a connective tissue disorder characterized by laxity. The skin, as one of the organs involved, shows hyperextensibility, which makes it prone to trauma. In this context, it would seem logical for cutaneous synovial metaplasia, which is considered a form of repair, to be commonly found in cases of EDS. However, there are only two previously published cases of synovial metaplasia in EDS. We present a third case in a 56-year-old woman with painful redundant skin in both elbows and knees for whom a skin fold of the left elbow was removed to relieve her symptoms. The biopsy showed preservation of the elastic and collagen fibers. The main alteration was the evidence of dermal cystic spaces lined by fibrinoid rests with focal pseudopapillary projections. However, in some zones the cellular lining was preserved, and it was composed of vimentin-positive, fibroblast-like flat, elongated cells, as well as CD68-positive macrophages. No birefringent particles were found in an examination under polarized light.

Appearance of Alveolar Macrophage Subpopulations in Correlation With Histopathological Effects in Short-Term Inhalation Studies With Biopersistent (Nano)Materials

Following inhalation and deposition in the alveolar region at sufficient dose, biopersistent (nano)materials generally provoke pulmonary inflammation. Alveolar macrophages (AMs) are mediators of pulmonary immune responses and were broadly categorized in pro-inflammatory M1 and anti-inflammatory M2 macrophages. This study aimed at identifying AM phenotype as M1 or M2 upon short-term inhalation exposure to different (nano)materials followed by a postexposure period. Phenotyping of AM was retrospectively performed using immunohistochemistry. M1 (CD68⁺iNOS⁺) and M2 (CD68⁺CD206⁺ and CD68⁺ArgI⁺) AMs were characterized in formalin-fixed, paraffin-embedded lung tissue of rats exposed for 6 hours/day for 5 days to air, 100 mg/m³ nano-TiO₂, 25 mg/m³ nano-CeO₂, 32 mg/m³ multiwalled carbon nanotubes, or 100 mg/m³ micron-sized quartz. During acute inflammation, relative numbers of M1 AMs were markedly increased, whereas relative numbers of M2 were generally decreased compared to control. Following an exposure-free period, changes in iNOS or CD206 expression correlated with persistence, regression, or progression of inflammation, suggesting a role of M1/M2 AMs in the pathogenesis of pulmonary inflammation. However, no clear correlation of AM subpopulations with qualitatively distinct histopathological findings caused by different (nano)materials was found. A more detailed understanding of the processes underlaying these morphological changes is needed to identify biomarkers for different histopathological outcomes.

Identification of a novel monocytic phenotype in Classic Hodgkin Lymphoma tumor microenvironment

Classic Hodgkin lymphoma (CHL) characteristically shows few malignant cells in a microenvironment comprised of mixed inflammatory cells. Although CHL is associated with a high cure rate, recent studies have associated poor prognosis with absolute monocyte count in peripheral blood and increased monocyte/macrophages in involved lymph nodes. Thus, the role of monocytic infiltration and macrophage differentiation in the tumor microenvironment of CHL may be more relevant than absolute macrophage numbers to defining prognosis in CHL patients and potentially have therapeutic implications. Most studies identify tumor-associated macrophages (TAMs) using markers (e.g., CD68) expressed by macrophages and other mononuclear phagocytes, such as monocytes. In contrast, Class A Scavenger Receptor (SR-A/CD204) is expressed by tissue macrophages but not monocytic precursors. In this study, we examined SR-A expression in CHL (n = 43), and compared its expression with that of other macrophage markers. We confirmed a high prevalence of mononuclear cells that stained with CD68, CD163, and CD14 in CHL lymph nodes. However, SR-A protein expression determined by immunohistochemistry was limited to macrophages localized in sclerotic bands characteristic of nodular sclerosis CHL. In contrast, SR-A protein was readily detectable in lymph nodes with metastatic tumor, extra-nodal CHL, T cell/histiocyte-rich large B cell lymphoma, and resident macrophages in non-malignant tissues, including spleen, lymph node, liver and lung. The results of SR-A protein expression paralleled the expression of SR-A mRNA determined by quantitative RT-PCR. These data provide evidence that tumor-infiltrating monocyte/macrophages in CHL have a unique phenotype that likely depends on the microenvironment of nodal CHL.

Profiling the Atlantic Salmon IgM+ B Cell Surface Proteome: Novel Information on Teleost Fish B Cell Protein Repertoire and Identification of Potential B Cell Markers

Fish immunology research is at a pivotal point with the increasing availability of functional immunoassays and major advances in omics approaches. However, studies on fish B cells and their distinct subsets remain a challenge due to the limited availability of differentially expressed surface markers. To address this constraint, cell surface proteome of Atlantic salmon IgM⁺ B cells were analyzed by mass spectrometry and compared to surface proteins detected from two adherent salmon head kidney cell lines, ASK and SSP-9. Out of 21 cluster of differentiation (CD) molecules identified on salmon IgM⁺ B cells, CD22 and CD79A were shortlisted as potential markers based on the reported B cell-specific surface expression of their mammalian homologs. Subsequent RT-qPCR analyses of flow cytometry-sorted subpopulations from head kidney leukocytes confirmed that both cd22 and cd79a genes were highly expressed in IgM⁺ lymphoid cells but were observed in barely detectable levels in IgM^- non-lymphoid suspension and adherent cells. Similarly, significantly high cd22 and cd79a mRNA levels were observed in IgM⁺ or IgT⁺ lymphoid cells from the spleen and peritoneal cavity, but not in their corresponding IgM^- IgT^- non-lymphoid fractions. This suggests that the B cell restrictive expression of CD22 and CD79A extend down to the transcription level, which was consistent across different lymphoid compartments and immunoglobulin isotypes, thus strongly supporting the potential of CD22 and CD79A as pan-B cell markers for salmon. In addition, this study provides novel information on the salmon B cell surface protein repertoire, as well as insights on B cell evolution. Further investigation of the identified salmon CD molecules, including development of immunological tools for detection, will help advance our understanding of the dynamics of salmon B cell responses such as during infection, vaccination, or immunostimulation.

Comparison of different cell culture plates for the enrichment of non-adherent human mononuclear cells

While tissue-resident monocytes and macrophages are considered to be vital players in the in vivo interaction between biomaterials and surrounding tissue, their isolation is limited. In order to establish in vitro models elucidating implant and tissue interactions, peripheral blood mononuclear cells (PBMCs) represent a viable source for bone marrow-derived monocytes and an alternative to tissue-resident cells. The aim of present study was to analyse different adhesion-preventing tissue culture plates for their potential to facilitate the culture of monocytes without differentiation into macrophages. Freshly isolated PBMCs were seeded into four commercially available tissue culture plates with different adhesive properties and were tested for surface CD14 and CD68 expression using flow cytometry following 7 days in culture. When PBMCs were cultivated in RPMI on Cellstar^® Cell culture plates with Cell-Repellent Surface, a significant increase in CD14-positive cells was observed compared with cultivation in standard tissue culture-treated plates. This was accompanied by elevated cytokine production of interleukin-6 (IL6) and interleukin-8 (IL8); however, overall cell growth was not affected. When PBMCs were pre-cultured in cell-repellent plates, there was a higher yield of adherent cells after subsequent transfer into standard tissue culture-treated plates. Cultivation of PBMCs on cell-repellent culture plates favoured a monocytic phenotype and thus, represents an alternative to increase the fraction of monocytes yielded from PBMCs.

Red blood cell-derived nanovesicles for safe and efficient macrophage-targeted drug delivery in vivo

RBC-derived nanovesicles are effective hydrophilic drug carriers and can effectively deliver drugs into macrophages both in vitro and in vivo.

An Injectable Reverse Thermal Gel for Minimally Invasive Coverage of Mouse Myelomeningocele

BACKGROUND

Myelomeningocele (MMC) results in lifelong neurologic and functional deficits. Currently, prenatal repair of MMC closes the defect, resulting in a 50% reduction in postnatal ventriculoperitoneal shunting. However, this invasive fetal surgery is associated with significant morbidities to mother and baby. We have pioneered a novel reverse thermal gel (RTG) to cover MMC defects in a minimally invasive manner. Here, we test in-vitro RTG long-term stability in amniotic fluid and in vivo application in the Grainy head-like 3 (Grhl3) mouse MMC model.

MATERIALS AND METHODS

RTG stability in amniotic fluid (in-vitro) was monitored for 6 mo and measured using gel permeation chromatography and solution-gel transition temperature (lower critical solution temperature). E16.5 Grhl3 mouse fetuses were injected with the RTG or saline and harvested on E19.5. Tissue was assessed for RTG coverage of the gross defect and inflammatory response by immunohistochemistry for macrophages.

RESULTS

Polymer backbone molecular weight and lower critical solution temperature remain stable in amniotic fluid after 6 mo. Needle injection over the MMC of Grhl3 fetuses successfully forms a stable gel that covers the entire defect. On harvest, some animals demonstrate >50% RTG coverage. RTG injection is not associated with inflammation.

CONCLUSIONS

Our results demonstrate that the RTG is a promising candidate for a minimally invasive approach to patch MMC. We are now poised to test our RTG patch in the large preclinical ovine model used to evaluate prenatal repair of MMC.

Immunological response to bacterial infection in a pelagic tunicate: Inflammation in the salp Thalia democratica

Thaliaceans are pelagic tunicates that play a key role in trophic chains of the oceans. In the field of tunicate immunity, a notable gap is the lack of data on their inflammatory response. The common salp, Thalia democratica, possesses scant immunocytes, represented by a phagocytic line (hyaline amebocytes) and a mast cell-like line (granular cells). We aimed to provide the first investigation of defense reactions upon exposure to a large amount of bacteria (Bacillus clausii). We detected (i) bacterial phagocytosis by hyaline amebocytes, (ii) degradation of phagocytizing hyaline amebocytes in the tunic after transcellular diapedesis from the hemocoel, and (iii) release of heparin, histamine, and TNF-α by granular cells. Cell degranulation and phagocytosis occurred in epidermal cells lining the hemocoel, and an excess of mucus was observed in the post-branchial gut, causing a functional inhibition of cilia and microvilli. These findings indicate multi-step events comparable to an inflammation involving responses at both tissue and organismal levels.

[18F]-Fluorodeoxyglucose PET/CT imaging as a marker of carotid plaque inflammation: Comparison to immunohistology and relationship to acuity of events

BACKGROUND

[18F]-fluorodeoxyglucose (¹⁸FDG) uptake imaged with positron emission tomography (PET) and computed tomography (CT) may serve as a biomarker of plaque inflammation. This study evaluated the relationship between carotid plaque ¹⁸FDG uptake and a) intraplaque expression of macrophage and macrophage-like cellular CD68 immunohistology; b) intraplaque inflammatory burden using leukocyte-sensitive CD45 immunohistology; c) symptomatic patient presentation; d) time from last cerebrovascular event.

METHODS

54 patients scheduled for carotid endarterectomy underwent ¹⁸FDG PET/CT imaging. Maximum 18FDG uptake (SUV_max) and tissue-to-blood ratio (TBR_max) was measured for carotid plaques. Quantitative immunohistological analysis of macrophage-like cell expression (CD68) and leukocyte content (CD45) was performed.

RESULTS

¹⁸FDG uptake was related to CD68 macrophage expression (TBR_max: r = 0.51, p < 0.001), and total-plaque leukocyte CD45 expression (TBR_max: r = 0.632, p = 0.009, p < 0.001). ¹⁸FDG TBR_max uptake in carotid plaque associated with patient symptoms was greater than asymptomatic plaque (3.58 ± 1.01 vs. 3.13 ± 1.10, p = 0.008). ¹⁸FDG uptake differed between an acuity threshold of <90 days and >90 days (SUV_max:3.15 ± 0.87 vs. 2.52 ± 0.45, p = 0.015).

CONCLUSIONS

In this CAIN cohort, ¹⁸FDG uptake imaged with PET/CT serves a surrogate marker of intraplaque inflammatory macrophage, macrophage-like cell and leukocyte burden. 18FDG uptake is greater in plaque associated with patient symptoms and those with recent cerebrovascular events. Future studies are needed to relate ¹⁸FDG uptake and disease progression.

Translocator Protein as an Imaging Marker of Macrophage and Stromal Activation in Rheumatoid Arthritis Pannus

PET radioligands targeted to translocator protein (TSPO) offer a highly sensitive and specific means of imaging joint inflammation in rheumatoid arthritis (RA). Through high expression of TSPO on activated macrophages, TSPO PET has been widely reported in several studies of RA as a means of imaging synovial macrophages in vivo. However, this premise does not take into account the ubiquitous expression of TSPO. This study aimed to investigate TSPO expression in major cellular constituents of RA pannus-monocytes, macrophages, fibroblastlike synoviocytes (FLS cells), and CD4-positive (CD4+) T lymphocytes (T cells)-to more accurately interpret TSPO PET signal from RA synovium. Methods: Three RA patients and 3 healthy volunteers underwent PET of both knees using the TSPO radioligand ¹¹C-PBR28. Through ³H-PBR28 autoradiography and immunostaining of synovial tissue in 6 RA patients and 6 healthy volunteers, cellular expression of TSPO in synovial tissue was evaluated. TSPO messenger RNA expression and ³H-PBR28 radioligand binding was assessed using in vitro monocytes, macrophages, FLS cells, and CD4+ T cells. Results:¹¹C-PBR28 PET signal was significantly higher in RA joints than in healthy joints (average SUV, 0.82 ± 0.12 vs. 0.03 ± 0.004; P < 0.01). Further, ³H-PBR28-specific binding in synovial tissue was approximately 10-fold higher in RA patients than in healthy controls. Immunofluorescence revealed TSPO expression on macrophages, FLS cells, and CD4+ T cells. The in vitro study demonstrated the highest TSPO messenger RNA expression and ³H-PBR28-specific binding in activated FLS cells, nonactivated M0 macrophages, and activated M2 reparative macrophages, with the least TSPO expression being in activated and nonactivated CD4+ T cells. Conclusion: To our knowledge, this study was the first evaluation of cellular TSPO expression in synovium, with the highest TSPO expression and PBR28 binding being found on activated synovial FLS cells and M2 macrophages. TSPO-targeted PET may therefore have a unique sensitivity in detecting FLS cells and macrophage-predominant inflammation in RA, with potential utility for assessing treatment response in trials using novel FLS-cell-targeted therapies.

Granular cell tumors of the tongue: fibroma or schwannoma

Background

Granular cell tumors are benign lesions that typically occur in the oral cavity, but can also be found in other sites. However, the characteristics of these tumors are unclear. Thus, the present study aimed to investigate the immunohistological characteristics of these tumors of the tongue.

Methods

Seven patients were treated for granular cell tumors of the tongue at our institution during 2003–2017. Paraffin-embedded specimens were available for all cases; thus, retrospective immunohistochemical analyses were performed.

Results

All cases exhibited cytoplasmic acidophilic granules in the muscle layer of the tumor. Both the normal nerve cells and tumor cells also stained positive for PGP9.5, NSE, calretinin, and GFAP. A nucleus of tumor cells was typically present in the margin. The PAS-positive granules were also positive for CD68 (a lysozyme glycoprotein marker). Various sizes of nerve fibers were observed in each tumor, and granular cells were observed in the nerve fibers of a representative case.

Conclusions

Based on our immunohistological findings, granular cell tumors may be derived from Schwann cells, and the presence of CD68 indicates that Wallerian degeneration after nerve injury may be a contributor to tumor formation. Thus, a safe surgical margin is needed to detect the infiltrative growth of granular cell tumors.

Immunohistochemical Identification of Human Skeletal Muscle Macrophages

Macrophages have well-characterized roles in skeletal muscle repair and regeneration. Relatively little is known regarding the role of resident macrophages in skeletal muscle homeostasis, extracellular matrix remodeling, growth, metabolism and adaptation to various stimuli including exercise and training. Despite speculation into macrophage contributions during these processes, studies characterizing macrophages in non-injured muscle are limited and methods used to identify macrophages vary. A standardized method for the identification of human resident skeletal muscle macrophages will aide in the characterization of these immune cells and allow for the comparison of results across studies. Here, we present an immunohistochemistry (IHC) protocol, validated by flow cytometry, to distinctly identify resident human skeletal muscle macrophage populations. We show that CD11b and CD206 double IHC effectively identifies macrophages in human skeletal muscle. Furthermore, the majority of macrophages in non-injured human skeletal muscle show a 'mixed' M1/M2 phenotype, expressing CD11b, CD14, CD68, CD86 and CD206. A relatively small population of CD11b+/CD206- macrophages are present in resting skeletal muscle. Changes in the relative abundance of this population may reflect important changes in the skeletal muscle environment. CD11b and CD206 IHC in muscle also reveals distinct morphological features of macrophages that may be related to the functional status of these cells.

Immunohistochemical Assessment of Leukocyte Involvement in Angiogenesis

Angiogenesis is a hallmark of cancer and is important for tumor growth, development, and metastasis. Leukocytes, including neutrophils, eosinophils, basophils, lymphocytes, and monocytes, are found invading many solid tumors, and this inflammation is often associated with tumorigenesis. Tumor-associated macrophages have been shown to be involved in tumor migration and metastasis and are modulators of tumor vascularization. Tumor-associated macrophages are a source of angiogenic factors, and pro-inflammatory cytokines involved in angiogenesis, lymphangiogenesis, and metastasis. Here we describe a method of quantifying the number of macrophages and their class within tumor tissue which can be compared with tumor blood and lymphatic microvessel density as a measure of angiogenesis and lymphangiogenesis. Although not described in depth, application of the methodology is described for other leukocyte populations, such as tumor-infiltrating lymphocytes.

IFNγ Enhances CD64-Potentiated Phagocytosis of Treponema pallidum Opsonized with Human Syphilitic Serum by Human Macrophages

Syphilis is a multi-stage, sexually transmitted disease caused by the spirochete Treponema pallidum (Tp). Considered broadly, syphilis can be conceptualized as a dualistic process in which spirochete-driven inflammation, the cause of clinical manifestations, coexists to varying extents with bacterial persistence. Inflammation is elicited in the tissues, along with the persistence of spirochetes to keep driving a robust immune response while evading host defenses; this duality is best exemplified during the florid, disseminated stage called secondary syphilis (SS). SS lesions typically contain copious amounts of spirochetes along with a mixed cellular infiltrate consisting of CD4⁺ T cells, CD8⁺ T cells, NK cells, plasma cells, and macrophages. In the rabbit model, Tp are cleared by macrophages via antibody-mediated opsonophagocytosis. Previously, we demonstrated that human syphilitic serum (HSS) promotes efficient uptake of Tp by human monocytes and that opsonophagocytosis of Tp markedly enhances cytokine production. Herein, we used monocyte-derived macrophages to study Tp–macrophage interactions ex vivo. In the absence of HSS, monocyte-derived macrophages internalized low numbers of Tp and secreted little cytokine (e.g., TNF). By contrast, these same macrophages internalized large numbers of unopsonized Borrelia burgdorferi and secreted robust levels of cytokines. Maturation of macrophages with M-CSF and IFNγ resulted in a macrophage phenotype with increased expression of HLA-DR, CD14, inducible nitric oxide synthase, TLR2, TLR8, and the Fcγ receptors (FcγR) CD64 and CD16, even in the absence of LPS. Importantly, IFNγ-polarized macrophages resulted in a statistically significant increase in opsonophagocytosis of Tp accompanied by enhanced production of cytokines, macrophage activation markers (CD40, CD80), TLRs (TLR2, TLR7, TLR8), chemokines (CCL19, CXCL10, CXCL11), and T_H1-promoting cytokines (IL-12, IL-15). Finally, the blockade of FcγRs, primarily CD64, significantly diminished spirochetal uptake and proinflammatory cytokine secretion by IFNγ-stimulated macrophages. Our ex vivo studies demonstrate the importance of CD64-potentiated uptake of opsonized Tp and suggest that IFNγ-activated macrophages have an important role in the context of early syphilis. Our study results also provide an ex vivo surrogate system for use in future syphilis vaccine studies.

The cellular and molecular determinants of emphysematous destruction in COPD

The introduction of microCT has made it possible to show that the terminal bronchioles are narrowed and destroyed before the onset of emphysematous destruction in COPD. This report extends those observations to the cellular and molecular level in the centrilobular phenotype of emphysematous destruction in lungs donated by persons with very severe COPD (n = 4) treated by lung transplantation with unused donor lungs (n = 4) serving as controls. These lung specimens provided companion samples to those previously examined by microCT (n = 61) that we examined using quantitative histology (n = 61) and gene expression profiling (n = 48). The histological analysis showed that remodeling and destruction of the bronchiolar and alveolar tissue is associated with macrophage, CD4, CD8, and B cell infiltration with increased formation of tertiary lymphoid organs. Moreover, gene set enrichment analysis showed that genes known to be expressed by natural killer (NK), lymphoid tissue inducer (LTi), and innate lymphoid cell 1 (ILC1) cells, but not ILC2 or ILC3 cells, were enriched in the expression profiles associated with CD4, CD8, and B cell infiltration. Based on these findings, we postulate that the centrilobular phenotype of emphysematous destruction COPD is driven by a Th1 response activated by infiltrating ILC1, NK, and LTi cells.

LAMPs: Shedding light on cancer biology

Lysosomes are important cytoplasmic organelles whose critical functions in cells are increasingly being understood. In particular, despite the long-standing accepted concept about the role of lysosomes as cellular machineries solely assigned to degradation, it has been demonstrated that they play active roles in homeostasis and even in cancer biology. Indeed, it is now well documented that during the process of cellular transformation and cancer progression lysosomes are changing localization, composition, and volume and, through the release of their enzymes, lysosomes can also enhance cancer aggressiveness. LAMPs (lysosome associated membrane proteins) represent a family of glycosylated proteins present predominantly on the membrane of lysosomes whose expression can vary among different tissues, suggesting a separation of functions. In this review we focus on the functions and roles of the different LAMP family members, with a particular emphasis on cancer progression and metastatic spread. LAMP proteins are involved in many different aspects of cell biology and can influence cellular processes such as phagocytosis, autophagy, lipid transport, and aging. Interestingly, for all the five members identified so far (LAMP1, LAMP2, LAMP3, CD68/Macrosialin/LAMP4, and BAD-LAMP/LAMP5), a role in cancer has been suggested. While this is well documented for LAMP1 and LAMP2, the involvement of the other three proteins in cancer progression and aggressiveness has recently been proposed and remains to be elucidated. Here we present different examples about how LAMP proteins can influence and support tumor growth and metastatic spread, emphasizing the impact of each single member of the family.

Ebola virus glycoprotein directly triggers T lymphocyte death despite of the lack of infection

Fatal outcomes of Ebola virus (EBOV) infections are typically preceded by a 'sepsis-like' syndrome and lymphopenia despite T cells being resistant to Ebola infection. The mechanisms that lead to T lymphocytes death remain largely unknown; however, the degree of lymphopenia is highly correlative with fatalities. Here we investigated whether the addition of EBOV or its envelope glycoprotein (GP) to isolated primary human CD4+ T cells induced cell death. We observed a significant decrease in cell viability in a GP-dependent manner, which is suggestive of a direct role of GP in T cell death. Using immunoprecipitation assays and flow cytometry, we demonstrate that EBOV directly binds to CD4+ T cells through interaction of GP with TLR4. Transcriptome analysis revealed that the addition of EBOV to CD4+ T cells results in the significant upregulation of pathways associated with interferon signaling, pattern recognition receptors and intracellular activation of NFκB signaling pathway. Both transcriptome analysis and specific inhibitors allowed identification of apoptosis and necrosis as mechanisms associated with the observed T cell death following exposure to EBOV. The addition of the TLR4 inhibitor CLI-095 significantly reduced CD4+ T cell death induced by GP. EBOV stimulation of primary CD4+ T cells resulted in a significant increase in secreted TNFα; inhibition of TNFα-mediated signaling events significantly reduced T cell death while inhibitors of both necrosis and apoptosis similarly reduced EBOV-induced T cell death. Lastly, we show that stimulation with EBOV or GP augments monocyte maturation as determined by an overall increase in expression levels of markers of differentiation. Subsequently, the increased rates of cellular differentiation resulted in higher rates of infection further contributing to T cell death. These results demonstrate that GP directly subverts the host's immune response by increasing the susceptibility of monocytes to EBOV infection and triggering lymphopenia through direct and indirect mechanisms.

Cerebrovascular Remodeling and Neuroinflammation is a Late Effect of Radiation-Induced Brain Injury in Non-Human Primates

Fractionated whole-brain irradiation (fWBI) is a mainstay of treatment for patients with intracranial neoplasia; however late-delayed radiation-induced normal tissue injury remains a major adverse consequence of treatment, with deleterious effects on quality of life for affected patients. We hypothesize that cerebrovascular injury and remodeling after fWBI results in ischemic injury to dependent white matter, which contributes to the observed cognitive dysfunction. To evaluate molecular effectors of radiation-induced brain injury (RIBI), real-time quantitative polymerase chain reaction (RT-qPCR) was performed on the dorsolateral prefrontal cortex (DLPFC, Brodmann area 46), hippocampus and temporal white matter of 4 male Rhesus macaques (age 6-11 years), which had received 40 Gray (Gy) fWBI (8 fractions of 5 Gy each, twice per week), and 3 control comparators. All fWBI animals developed neurologic impairment; humane euthanasia was elected at a median of 6 months. Radiation-induced brain injury was confirmed histopathologically in all animals, characterized by white matter degeneration and necrosis, and multifocal cerebrovascular injury consisting of perivascular edema, abnormal angiogenesis and perivascular extracellular matrix deposition. Herein we demonstrate that RIBI is associated with white matter-specific up-regulation of hypoxia-associated lactate dehydrogenase A (LDHA) and that increased gene expression of fibronectin 1 (FN1), SERPINE1 and matrix metalloprotease 2 (MMP2) may contribute to cerebrovascular remodeling in late-delayed RIBI. Additionally, vascular stability and maturation associated tumor necrosis super family member 15 (TNFSF15) and vascular endothelial growth factor beta (VEGFB) mRNAs were increased within temporal white matter. We also demonstrate that radiation-induced brain injury is associated with decreases in white matter-specific expression of neurotransmitter receptors SYP, GRIN2A and GRIA4. We additionally provide evidence that macrophage/microglial mediated neuroinflammation may contribute to RIBI through increased gene expression of the macrophage chemoattractant CCL2 and macrophage/microglia associated CD68. Global patterns in cerebral gene expression varied significantly between regions examined (P < 0.0001, Friedman's test), with effects most prominent within cerebral white matter.

FOXO1, PXK, PYCARD and SAMD9L are differentially expressed by fibroblast-like cells in equine synovial membrane compared to joint capsule

Background

The synovial membrane lines the luminal side of the joint capsule in synovial joints. It maintains joint homeostasis and plays a crucial role in equine joint pathology. When trauma or inflammation is induced in a joint, the synovial membrane influences progression of joint damage. Equine synovial membrane research is hampered by a lack of markers of fibroblast-like synoviocytes (FLS) to distinguish FLS from other fibroblast-like cells in musculoskeletal connective tissues. The aim of this study is to identify potential FLS markers of the equine synovial membrane using microarray to compare between gene expression in equine synovial membrane and the joint capsule in metacarpophalangeal joints.

Results

Microarray analysis of tissues from 6 horses resulted in 1167 up-regulated genes in synovial membrane compared with joint capsule. Pathway analysis resulted in 241 candidate genes. Of these, 15 genes were selected for further confirmation as genes potentially expressed by fibroblast-like synoviocytes. Four genes: FOXO1, PXK, PYCARD and SAMD9L were confirmed in 9 horses by qPCR as differentially expressed in synovial membrane compared to joint capsule.

Conclusions

In conclusion, FOXO1, PXK, PYCARD and SAMD9L were confirmed as differentially expressed in synovial membrane compared to joint capsule. These four genes are potential markers of fibroblast-like synoviocytes of the synovial membrane. As these genes are overexpressed in synovial membrane compared to joint capsule, these genes could shed light on synovial membrane physiology and its role in joint disease.

Profiling cellular and inflammatory changes in the airway wall of mild to moderate COPD

BACKGROUND AND OBJECTIVE

The objective of this study was to enumerate total cells and the number of inflammatory cell differentials in large airways (LAs) versus small airways (SAs) of mild-moderate COPD, and against appropriate controls.

METHODS

For LA, we used endobronchial biopsies and for SA resected lung tissues. Immunostaining was enumerated (cells per mm² ) for macrophages, neutrophils, CD4 and CD8 T cells in the lamina propria (LP) up to 150 µM deep for LA and full wall thickness for SA.

RESULTS

We confirmed hypocellularity in the LA and in the SA wall in smokers and COPD (P < 0.001). LA cellularity was least in current smokers with COPD (COPD-CS) (P < 0.01), while SA cellularity was similar across smoker/COPD groups. LA neutrophils were decreased in COPD-CS (P < 0.01), while SA neutrophil counts were unchanged. Compared with controls, LA macrophage numbers in COPD were significantly lower (P < 0.05), with SA macrophage numbers unchanged. A significant increase was observed in SA CD8+ cells in both normal smokers (P < 0.01) and COPD-CS (P < 0.001) but not in LA.

CONCLUSION

These unique data indicate that the current model for airway wall inflammation in COPD is oversimplified, and contrast with innate inflammatory activation in the lumen, at least in mild-moderate disease. Any abnormalities in airway wall cell differentials are small, although exaggerated in percentage terms.

Meta-analysis of the prognostic and clinical value of tumor-associated macrophages in adult classical Hodgkin lymphoma

BACKGROUND

The prognostic significance of tumor-associated macrophages (TAM) in adult classical Hodgkin lymphoma (cHL) remains controversial. Here, we report a meta-analysis of the association of CD68 and CD163 infiltration on the clinical outcome of adult cHL.

METHODS

A comprehensive search to identify relevant articles was performed in PubMed, Embase, and Google Scholar on January 31, 2016. Using the fixed effect or random effects model of DerSimonian and Laird, hazard ratios (HR) or odds ratios (OR) with 95 % confidence intervals (CIs) were used as the effect size estimate.

RESULTS

Twenty-two eligible studies with a total of 2959 patients were identified. Our analysis indicated that a high density of CD68⁺ TAMs in the tumor microenvironment of adult cHL predicted poor overall survival (OS) (HR: 2.41; 95 % CI, 1.92-3.03), shorter progression-free survival (PFS) (HR: 1.78; 95 % CI, 1.45-2.18), and poor disease-specific survival (HR: 2.71; 95 % CI, 1.38-5.29). High density of CD163⁺ TAMs in the tumor microenvironment of adult cHL also predicted poor OS (HR: 2.75; 95 % CI, 1.58-4.78) and poor PFS (HR: 1.66; 95 % CI, 1.22-2.27). In addition, we demonstrated that a high density of either CD68⁺ or CD163⁺ TAMs was associated with the presence of Epstein-Barr virus in neoplastic cells (OR_CD68: 3.13; 95 % CI, 2.02-4.84; OR_CD163: 2.88; 95 % CI, 1.55-5.34). A high density of either CD68⁺ or CD163⁺ TAMs tend to be associated with a more advanced clinical stage (OR_CD68: 1.25; 95 % CI, 0.93-1.67; OR _CD163: 1.19; 95 % CI, 0.86-1.63), B-symptoms (OR_CD68: 1.35; 95 % CI, 0.90-2.01; OR_CD163: 2.19; 95 % CI, 0.96-5.03), higher International Prognostic Factors Project Score (OR_CD68: 1.20; 95 % CI, 0.67-2.15; OR_CD163: 2.00; 95 % CI, 0.92-4.35), and bulky disease (OR_CD68: 1.47; 95 % CI, 0.88-2.47; OR_CD163: 1.19; 95 % CI, 0.72-1.96).

CONCLUSIONS

Our analyses suggest that a high density of either CD68⁺ or CD163⁺ TAMs is a robust predictor of adverse outcomes in adult cHL. Increased TAMs should be taken into account to further improve prognostic stratification and the planning of appropriate therapeutic strategies.

Functional Immune Anatomy of the Liver-As an Allograft

The liver is an immunoregulatory organ in which a tolerogenic microenvironment mitigates the relative "strength" of local immune responses. Paradoxically, necro-inflammatory diseases create the need for most liver transplants. Treatment of hepatitis B virus, hepatitis C virus, and acute T cell-mediated rejection have redirected focus on long-term allograft structural integrity. Understanding of insults should enable decades of morbidity-free survival after liver replacement because of these tolerogenic properties. Studies of long-term survivors show low-grade chronic inflammatory, fibrotic, and microvascular lesions, likely related to some combination of environment insults (i.e. abnormal physiology), donor-specific antibodies, and T cell-mediated immunity. The resultant conundrum is familiar in transplantation: adequate immunosuppression produces chronic toxicities, while lightened immunosuppression leads to sensitization, immunological injury, and structural deterioration. The "balance" is more favorable for liver than other solid organ allografts. This occurs because of unique hepatic immune physiology and provides unintended benefits for allografts by modulating various afferent and efferent limbs of allogenic immune responses. This review is intended to provide a better understanding of liver immune microanatomy and physiology and thereby (a) the potential structural consequences of low-level, including allo-antibody-mediated injury; and (b) how liver allografts modulate immune reactions. Special attention is given to the microvasculature and hepatic mononuclear phagocytic system.

Immunohistochemical detection of CD14 and combined assessment with CD32B and CD68 for wound age estimation

Estimation of wound age is a major topic of study for forensic pathologists, but few markers exist that can indicate a specific period 1-5 days postinfliction, and a method to estimate wound age with high accuracy has not yet been established. This study examined CD14 as such a marker in mouse skin wounds of different ages (0min and 1, 2, 3, 5, 7, and 9 days) and in human subjects (group 1, 0-1 day; group 2, 1-5 days; group 3, >7 days) using Western blot analysis and/or immunohistochemical staining. In addition, we evaluated a combination of immunohistochemical markers in human skin wounds using transmembrane proteins, CD14, CD32B, and CD68, expressed on inflammatory cells. The expression of CD14 was detected only during 1-5 days postinfliction and, thus, the evaluation of CD14-expressing cells could specify wound age during 1-5 days postinfliction in mouse skin wounds. The ratio of samples assessed to be CD14(+) was significantly high in human skin wounds in group 2. Combined assessment using the three markers increased the specificity of diagnosis and shortened the range of wound age, compared with the assessment using a single marker. Our results indicate that CD14 may be a useful marker of wound age, 1-5 days postinfliction, and that combined assessment with CD14, CD32B, and CD68 may be a good method for the accurate estimation of wound age.

Immunohistochemistry for the detection of neural and inflammatory cells in equine brain tissue

Phenotypic characterization of cellular responses in equine infectious encephalitides has had limited description of both peripheral and resident cell populations in central nervous system (CNS) tissues due to limited species-specific reagents that react with formalin-fixed, paraffin embedded tissue (FFPE). This study identified a set of antibodies for investigating the immunopathology of infectious CNS diseases in horses. Multiple commercially available staining reagents and antibodies derived from antigens of various species for manual immunohistochemistry (IHC) were screened. Several techniques and reagents for heat-induced antigen retrieval, non-specific protein blocking, endogenous peroxidase blocking, and visualization-detection systems were tested during IHC protocol development. Boiling of slides in a low pH, citrate-based buffer solution in a double-boiler system was most consistent for epitope retrieval. Pressure-cooking, microwaving, high pH buffers, and proteinase K solutions often resulted in tissue disruption or no reactivity. Optimal blocking reagents and concentrations of each working antibody were determined. Ultimately, a set of monoclonal (mAb) and polyclonal antibodies (pAb) were identified for CD3⁺ (pAb A0452, Dako) T-lymphocytes, CD79αcy⁺ B-lymphocytes (mAb HM57, Dako), macrophages (mAb MAC387, Leica), NF-H⁺ neurons (mAb NAP4, EnCor Biotechnology), microglia/macrophage (pAb Iba-1, Wako), and GFAP⁺ astrocytes (mAb 5C10, EnCor Biotechnology). In paraffin embedded tissues, mAbs and pAbs derived from human and swine antigens were very successful at binding equine tissue targets. Individual, optimized protocols are provided for each positively reactive antibody for analyzing equine neuroinflammatory disease histopathology.

Tracking of Inhaled Near-Infrared Fluorescent Nanoparticles in Lungs of SKH-1 Mice with Allergic Airway Inflammation

Molecular imaging of inflammatory lung diseases, such as asthma, has been limited to date. The recruitment of innate immune cells to the airways is central to the inflammation process. This study exploits these cells for imaging purposes within the lung, using inhaled polystyrene nanoparticles loaded with the near-infrared fluorescence dye Itrybe (Itrybe-NPs). By means of in vivo and ex vivo fluorescence reflectance imaging of an ovalbumin-based allergic airway inflammation (AAI) model in hairless SKH-1 mice, we show that subsequent to intranasal application of Itrybe-NPs, AAI lungs display fluorescence intensities significantly higher than those in lungs of control mice for at least 24 h. Ex vivo immunofluorescence analysis of lung tissue demonstrates the uptake of Itrybe-NPs predominantly by CD68(+)CD11c(+)ECF-L(+)MHCII(low) cells, identifying them as alveolar M2 macrophages in the peribronchial and alveolar areas. The in vivo results were validated by confocal microscopy, overlapping tile analysis, and flow cytometry, showing an amount of Itrybe-NP-containing macrophages in lungs of AAI mice significantly larger than that in controls. A small percentage of NP-containing cells were identified as dendritic cells. Flow cytometry of tracheobronchial lymph nodes showed that Itrybe-NPs were negligible in lung draining lymph nodes 24 h after inhalation. This imaging approach may advance preclinical monitoring of AAI in vivo over time and aid the investigation of the role that macrophages play during lung inflammation. Furthermore, it allows for tracking of inhaled nanoparticles and can hence be utilized for studies of the fate of potential new nanotherapeutics.