Generation of macrophages from peripheral blood monocytes in the rhesus monkey

Primary infection with Zika virus provides one-way heterologous protection against Spondweni virus infection in rhesus macaques

Spondweni virus (SPONV) is the closest known relative of Zika virus (ZIKV). SPONV pathogenesis resembles that of ZIKV in pregnant mice, and both viruses are transmitted by Aedes aegypti mosquitoes. We aimed to develop a translational model to further understand SPONV transmission and pathogenesis. We found that cynomolgus macaques (Macaca fascicularis) inoculated with ZIKV or SPONV were susceptible to ZIKV but resistant to SPONV infection. In contrast, rhesus macaques (Macaca mulatta) supported productive infection with both ZIKV and SPONV and developed robust neutralizing antibody responses. Crossover serial challenge in rhesus macaques revealed that SPONV immunity did not protect against ZIKV infection, whereas ZIKV immunity was fully protective against SPONV infection. These findings establish a viable model for future investigation into SPONV pathogenesis and suggest that the risk of SPONV emergence is low in areas with high ZIKV seroprevalence due to one-way cross-protection between ZIKV and SPONV.

Protective effects of oridonin against osteoporosis by regulating immunity and activating the Wnt3a/β-catenin/VEGF pathway in ovariectomized mice

This study was performed with the aim of investigating the effect of oridonin (ORI) on estrogen deprivation-induced osteoporosis in mice and its mechanism. Animal experiments were used in this work to validate the anti-osteoporotic efficacy of ORI. Morphometric analysis was performed by micro-CT. A special protein meter was used to detect the content of immunoglobulin lgM, immunoglobulin lgG, complement C3 and C4 in the serum of mice. The expression of CD4⁺CD25⁺Foxp3⁺ Treg cell and CD4⁺/CD8⁺ lymphocyte subsets in mice was detected by flow cytometry. ELISA was used to detect the content of insulin-like growth factor (IGF-1), tumor necrosis factor (TNF-α), interleukin-1 (IL-1) and interleukin-6 (IL-6). In addition, key signaling molecules in the Wnt3a/β-catenin signaling pathway were detected by Western blotting. The results showed that compared with the model group, the contents of calcium and phosphorus in the femurs of mice in the ORI groups were increased, and the spleen coefficient was decreased. The ALP activity in the serum of mice in the high and medium dose ORI groups was decreased, and the uterine coefficient was increased. ORI significantly increased the maximum bending load and the maximum bending stress of the femurs of mice, increased the number of trabeculae, and repaired the bone microstructure. At the same time, ORI could significantly increase the levels of immunoglobulin (lgG and lgM) and complement (C3 and C4), increase the activity of peritoneal macrophages in mice, increase the expression of CD4⁺CD25⁺Foxp3⁺ Tregs and CD4⁺/CD8⁺ in the spleen, increase the content of IGF-1, reduce the content of TNF-α, IL-1 and IL-6 and increase the expression levels of VEGF, Wnt3a, p-GSK3β/GSK3β and β-catenin/Lamin in the femoral tissue. These results indicated that ORI might regulate the expression of VEGF through the Wnt3a/β-catenin signaling pathway, improve the immunity of mice, maintain the balance of the immune system, and promote angiogenesis, thereby improving the bone mineral density and bone tissue morphology of mice and playing an anti-osteoporotic role.

A Biomaterial Model to Assess the Effects of Age in Vascularization

As humans age, there is an increased risk for developing age-associated diseases. Many of these diseases, such as cardiovascular disease, involve dysfunction in the vasculature. Cardiovascular disease stems from endothelial cell dysfunction and reduction in vascularization. Macrophages, prominent innate immune cells involved in orchestrating inflammation and wound healing, have a significant influence on vascularization. While much recent work has investigated the crosstalk between endothelial cells and macrophages, it is still not well defined. The interactions between the cell types are even less understood in specific disease states such as advanced age. Understanding how age influences macrophage/endothelial cell interaction is essential for understanding cardiovascular disease development in the elderly. In the polyethylene glycol (PEG)-based hydrogel system, we model the effects of age on vascularization by encapsulating endothelial cells, pericytes, and human donor macrophages. We created a biomaterial model system in which macrophages, either from young (<35 years old) or old (>65 years old) donors, interact with the modeled vasculature, termed microvessels. Confocal image analysis of vessel density, vessel length, and branch points were used to quantify microvessel growth depending on the age of the macrophage donor. Alongside this, soluble factor secretion and gene expression were evaluated using ELISA and NanoString to showcase biological mechanisms based on the age of each donor. Endothelial cells cultured with macrophages from old donors have reduced microvessel density. There also is reduced soluble factor secretion by the macrophages from old donors, which likely influenced microvessel growth. Altogether, we establish our PEG-based hydrogel vascular model as a system to evaluate patient-specific cell function as well as proposed mechanisms for how age influences microvessels.

Impact of ferumoxytol magnetic resonance imaging on the rhesus macaque maternal-fetal interface†

Ferumoxytol is a superparamagnetic iron oxide nanoparticle used off-label as an intravascular magnetic resonance imaging (MRI) contrast agent. Additionally, ferumoxytol-uptake by macrophages facilitates detection of inflammatory sites by MRI through ferumoxytol-induced image contrast changes. Therefore, ferumoxytol-enhanced MRI holds great potential for assessing vascular function and inflammatory response, critical to determine placental health in pregnancy. This study sought to assess the fetoplacental unit and selected maternal tissues, pregnancy outcomes, and fetal well-being after ferumoxytol administration. In initial developmental studies, seven pregnant rhesus macaques were imaged with or without ferumoxytol administration. Pregnancies went to term with vaginal delivery and infants showed normal growth rates compared to control animals born the same year that did not undergo MRI. To determine the impact of ferumoxytol on the maternal-fetal interface (MFI), fetal well-being, and pregnancy outcome, four pregnant rhesus macaques at ~100 gestational day underwent MRI before and after ferumoxytol administration. Collection of the fetoplacental unit and selected maternal tissues was performed 2-3 days following ferumoxytol administration. A control group that did not receive ferumoxytol or MRI was used for comparison. Iron levels in fetal and MFI tissues did not differ between groups, and there was no significant difference in tissue histopathology with or without exposure to ferumoxytol, and no effect on placental hormone secretion. Together, these results suggest that the use of ferumoxytol and MRI in pregnant rhesus macaques does not negatively impact the MFI and can be a valuable experimental tool in research with this important animal model.

Crosstalk Between Cardiac Cells and Macrophages Postmyocardial Infarction: Insights from In Vitro Studies

Cardiovascular disease, including myocardial infarction (MI), is the leading cause of death in the western world. Following MI, a large number of cardiomyocytes are lost and inflammatory cells such as monocytes and macrophages migrate into the damaged region to remove dead cells and tissue. These inflammatory cells secrete growth factors to induce degradation of the extracellular matrix in the myocardium and recruit cardiac fibroblasts. However, the contribution of specific macrophage subsets on cardiac cell function and survival in the steady state as well as in the diseased state is not well known. There is an increasing demand for in vitro cardiac disease models to bridge the critical missing link in the existing experimental methods. In this review, studies using in vitro models to examine the interaction between macrophages and cardiac cells, including cardiomyocytes, endothelial cells, and fibroblasts, are summarized to better understand the complex inflammatory cascade post-MI. The current challenges and the future directions of in vitro cardiac models are also discussed. Detailed and more mechanistic insights into macrophages and cardiac cell interactions during the multiphase repair process could potentially revolutionize the development of treatments and diagnostic alternatives. Impact statement The inflammatory cascade postmyocardial infarction (MI) is very complex. In vitro cardiac disease model studies bridge the critical missing link in the existing experimental methods and provide insights, including multicellular interaction post-MI. Detailed and more mechanistic insights into macrophages and cardiac cell interactions during the multiphase repair process could potentially revolutionize in developing treatments and diagnostic alternatives.

Metabolic Syndrome Exacerbates Pulmonary Hypertension due to Left Heart Disease

RATIONALE

Pulmonary hypertension (PH) due to left heart disease (LHD), or group 2 PH, is the most prevalent form of PH worldwide. PH due to LHD is often associated with metabolic syndrome (MetS). In 12% to 13% of cases, patients with PH due to LHD display vascular remodeling of pulmonary arteries (PAs) associated with poor prognosis. Unfortunately, the underlying mechanisms remain unknown; PH-targeted therapies for this group are nonexistent, and the development of a new preclinical model is crucial. Among the numerous pathways dysregulated in MetS, inflammation plays also a critical role in both PH and vascular remodeling.

OBJECTIVE

We hypothesized that MetS and inflammation may trigger the development of vascular remodeling in group 2 PH.

METHODS AND RESULTS

Using supracoronary aortic banding, we induced diastolic dysfunction in rats. Then we induced MetS by a combination of high-fat diet and olanzapine treatment. We used metformin treatment and anti-IL-6 (interleukin-6) antibodies to inhibit the IL-6 pathway. Compared with sham conditions, only supracoronary aortic banding+MetS rats developed precapillary PH, as measured by both echocardiography and right/left heart catheterization. PH in supracoronary aortic banding+MetS was associated with macrophage accumulation and increased IL-6 production in lung. PH was also associated with STAT3 (signal transducer and activator of transcription 3) activation and increased proliferation of PA smooth muscle cells, which contributes to remodeling of distal PA. We reported macrophage accumulation, increased IL-6 levels, and STAT3 activation in the lung of group 2 PH patients. In vitro, IL-6 activates STAT3 and induces human PA smooth muscle cell proliferation. Metformin treatment decreased inflammation, IL-6 levels, STAT3 activation, and human PA smooth muscle cell proliferation. In vivo, in the supracoronary aortic banding+MetS animals, reducing IL-6, either by anti-IL-6 antibody or metformin treatment, reversed pulmonary vascular remodeling and improve PH due to LHD.

CONCLUSIONS

We developed a new preclinical model of group 2 PH by combining MetS with LHD. We showed that MetS exacerbates group 2 PH. We provided evidence for the importance of the IL-6-STAT3 pathway in our experimental model of group 2 PH and human patients.

Generation of Macrophages from Cynomolgus-Monkey Bone Marrow as a Model to Evaluate Effects of Drugs on Innate Immunity

Macrophages are innate immune cells that play important roles in various physiological and pathological processes. Evaluation of pro-inflammatory effects of drugs on macrophages has become commonplace in preclinical drug development prior to human clinical trials. Despite their body-wide distribution, tissue macrophages are often difficult to collect from large animals and humans in a noninvasive manner. Therefore, in vitro-differentiated macrophages are important tools to facilitate cross-species analysis of macrophage function. Although cynomolgus monkeys are an essential non-rodent species for preclinical research, in vitro differentiation of cynomolgus-monkey macrophages has been poorly characterized. In the present unit, we describe a protocol to differentiate cynomolgus-monkey macrophages from isolated bone marrow mononuclear cells (BMMCs). In contrast to monocytes, cynomolgus-monkey BMMCs show robust expansion in the presence of macrophage colony-stimulating factor in vitro, which allows expansion of many cells from a single animal donor. Macrophages differentiated from BMMCs retain many of the macrophage phenotypes and functions, including phagocytosis and cytokine release, and therefore can be used as a surrogate to assess effects of drugs on cynomolgus-monkey macrophages. © 2019 by John Wiley & Sons, Inc.

Insulin regulates multiple signaling pathways leading to monocyte/macrophage chemotaxis into the wound tissue

Wound healing is a complex process that involves sequential phases that overlap in time and space and affect each other dynamically at the gene and protein levels. We previously showed that insulin accelerates wound healing by stimulating faster and regenerative healing. One of the processes that insulin stimulates is an increase in monocyte/macrophage chemotaxis. In this study, we performed experiments in vivo and in vitro to elucidate the signaling transduction pathways that are involved in insulin-induced monocyte/macrophage chemotaxis. We found that insulin stimulates THP-1 cell chemotaxis in a dose-dependent and insulin receptor-dependent manner. We also show that the kinases PI3K-Akt, SPAK/JNK, and p38 MAPK are key molecules in the insulin-induced signaling pathways that lead to chemoattraction of the THP-1 cell. Furthermore, both PI3K-Akt and SPAK/JNK signaling involve Rac1 activation, an important molecule in regulating cell motility. Indeed, topical application of Rac1 inhibitor at an early stage during the healing process caused delayed and impaired healing even in the presence of insulin. These results delineate cell and molecular mechanisms involved in insulin-induced chemotaxis of monocyte/macrophage, cells that are critical for proper healing.

Summary: Insulin regulates multiple signaling pathways leading to monocyte/macrophage chemotaxis into the wound tissue, involving -Akt, SPAK/JNK, and p38 MAPK which in turn are involved in Rac1 activation. Furthermore, these results augment our understanding of the insulin-regulated wound inflammatory response.

Macrophages modulate the growth and differentiation of rhesus monkey embryonic trophoblasts

PROBLEM

Immune cells within the endometrium at implantation are thought to play an important role in implantation, although their exact role is not well understood.

METHOD OF STUDY

A co-culture system of rhesus monkey embryos and maternal immune cells was established. Blastocysts obtained by in vitro fertilization were co-cultured with peripheral blood cells or decidual macrophages. Culture media were collected to assess secretions. Embryo growth was monitored, and trophoblasts were evaluated for proliferation, apoptosis, and differentiation.

RESULTS

Embryonic trophoblast outgrowths were visible within 6 days of culture, and the area of embryo outgrowth was reduced when blastocysts were cultured with peripheral-derived or decidual macrophages. Trophoblast proliferation was not significantly affected with macrophage co-culture while chorionic gonadotropin secretion was increased. Trophoblast expression of CDH 11 and GJA1 was increased, suggesting that macrophages accelerate differentiation of peri-implantation trophoblasts.

CONCLUSIONS

These results indicate an important role of macrophages in placentation and pregnancy success.

Vascular niche promotes hematopoietic multipotent progenitor formation from pluripotent stem cells

Pluripotent stem cells (PSCs) represent an alternative hematopoietic stem cell (HSC) source for treating hematopoietic disease. The limited engraftment of human PSC-derived (hPSC-derived) multipotent progenitor cells (MPP) has hampered the clinical application of these cells and suggests that MPP require additional cues for definitive hematopoiesis. We hypothesized that the presence of a vascular niche that produces Notch ligands jagged-1 (JAG1) and delta-like ligand-4 (DLL4) drives definitive hematopoiesis. We differentiated hes2 human embryonic stem cells (hESC) and Macaca nemestrina-induced PSC (iPSC) line-7 with cytokines in the presence or absence of endothelial cells (ECs) that express JAG1 and DLL4. Cells cocultured with ECs generated substantially more CD34+CD45+ hematopoietic progenitors compared with cells cocultured without ECs or with ECs lacking JAG1 or DLL4. EC-induced cells exhibited Notch activation and expressed HSC-specific Notch targets RUNX1 and GATA2. EC-induced PSC-MPP engrafted at a markedly higher level in NOD/SCID/IL-2 receptor γ chain-null (NSG) mice compared with cytokine-induced cells, and low-dose chemotherapy-based selection further increased engraftment. Long-term engraftment and the myeloid-to-lymphoid ratio achieved with vascular niche induction were similar to levels achieved for cord blood-derived MPP and up to 20-fold higher than those achieved with hPSC-derived MPP engraftment. Our findings indicate that endothelial Notch ligands promote PSC-definitive hematopoiesis and production of long-term engrafting CD34+ cells, suggesting these ligands are critical for HSC emergence.

Application of paclitaxel in low non-cytotoxic doses supports vaccination with melanoma antigens in normal mice

Chemotherapeutic agents such as paclitaxel applied in ultra-low, non-cytotoxic doses were previously shown to stimulate dendritic cell activity and anti-tumor immune responses upon vaccination in mouse transplantable tumor models. However, the mechanisms of these alterations-termed chemoimmunomodulation or chemomodulation-are still not clear. This study investigated the effect of paclitaxel applied in ultra-low, non-cytotoxic doses on the efficiency of immunization of healthy C57BL/6 mice with the peptide derived from tyrosinase related protein (TRP)-2 as a model melanoma antigen. Using an IFNγ ELISPOT assay, it was found that administration of 1 mg paclitaxel/kg in combination with the peptide vaccination strongly increased the frequencies of TRP-2 specific spleen T-cells as compared to levels due to the vaccination alone. This was associated with a significant decrease in the levels of regulatory T-cells (T(reg)) and immature myeloid cells (known as a counterpart of myeloid derived suppressor cells [MDSC] in healthy mice). Such impairments of potential immunosuppressive cells were found to correlate with a strong increase in the amount of effector CD8+ and CD4+ T-cells in the bone marrow and spleen. Furthermore, in paclitaxel-treated mice, a significant augmentation of natural killer (NK) cell numbers in the bone marrow and their ability to produce IFNγ were observed. In addition, the level of NK-T-cells in the lymph nodes was also increased. It is suggested that paclitaxel applied in ultra-low, non-cytotoxic doses may potentially enhance the efficacy of anti-tumor vaccinations by neutralizing immunosuppressive T(reg) and MDSC populations in tumor-bearing hosts.

Immunophenotype and cytokine profiles of rhesus monkey CD56bright and CD56dim decidual natural killer cells

The primate endometrium is characterized in pregnancy by a tissue-specific population of CD56(bright) natural killer (NK) cells. These cells are observed in human, rhesus, and other nonhuman primate decidua. However, other subsets of NK cells are present in the decidua and may play distinct roles in pregnancy. The purpose of this study was to define the surface marker phenotype of rhesus monkey decidual NK (dNK) cell subsets, and to address functional differences by profiling cytokine and chemokine secretion in contrast with decidual T cells and macrophages. Rhesus monkey decidual leukocytes were obtained from early pregnancy tissues, and were characterized by flow cytometry and multiplex assay of secreted factors. We concluded that the major NK cell population in rhesus early pregnancy decidua are CD56(bright) CD16(+)NKp30(-) decidual NK cells, with minor CD56(dim) and CD56(neg) dNK cells. Intracellular cytokine staining demonstrated that CD56(dim) and not CD56(bright) dNK cells are the primary interferon-gamma (IFNG) producers. In addition, the profile of other cytokines, chemokines, and growth factors secreted by these two dNK cell populations was generally similar, but distinct from that of peripheral blood NK cells. Finally, analysis of multiple pregnancies from eight dams revealed that the decidual immune cell profile is characteristic of an individual animal and is consistently maintained across successive pregnancies, suggesting that the uterine immune environment in pregnancy is carefully regulated in the rhesus monkey decidua.

Modulation of cytokine and chemokine secretions in rhesus monkey trophoblast co-culture with decidual but not peripheral blood monocyte-derived macrophages

PROBLEM

Decidual macrophages are thought to promote pregnancy success, in part through interactions with invading trophoblast cells in hemochorial placentation. However, the factors that constitute this regulatory cross talk are not well understood.

METHOD OF STUDY

Rhesus monkey decidual and peripheral blood-derived macrophages were co-cultured with primary Rhesus trophoblasts. Macrophage functions including cell-surface marker expression, antigen uptake and processing, in vitro migration, and cytokine and chemokine secretions were evaluated.

RESULTS

While most macrophage functions were unchanged by trophoblast co-culture, changes in the secretion of selected cytokines and the migration of trophoblasts were noted when decidual (but generally, not peripheral blood monocyte-derived) macrophages were cultured with trophoblasts. In addition, basal secretion differed significantly between peripheral blood-derived and decidual macrophages for a broad spectrum of cytokines. When trophoblasts were pre-treated with an anti-Mamu-AG antibody, 25D3, there was no change in cytokine or chemokine secretion.

CONCLUSION

Macrophage cytokine expression can be modulated by trophoblast co-culture, but it remains unclear how Mamu-AG is involved.