Hypoxia enhances the proliferative response of macrophages to CSF-1 and their pro-survival response to TNF

Hyperthermia Influences the Secretion Signature of Tumor Cells and Affects Endothelial Cell Sprouting

Tumors are a highly heterogeneous mass of tissue showing distinct therapy responses. In particular, the therapeutic outcome of tumor hyperthermia treatments has been inconsistent, presumably due to tumor versus endothelial cell cross-talks related to the treatment temperature and the tumor tissue environment. Here, we investigated the impact of the average or strong hyperthermic treatment (43 °C or 47 °C for 1 h) of the human pancreatic adenocarcinoma cell line (PANC-1 and BxPC-3) on endothelial cells (HUVECs) under post-treatment normoxic or hypoxic conditions. Immediately after the hyperthermia treatment, the distinct repression of secreted pro-angiogenic factors (e.g., VEGF, PDGF-AA, PDGF-BB, M-CSF), intracellular HIF-1α and the enhanced phosphorylation of ERK1/2 in tumor cells were detectable (particularly for strong hyperthermia, 2D cell monolayers). Notably, there was a significant increase in endothelial sprouting when 3D self-organized pancreatic cancer cells were treated with strong hyperthermia and the post-treatment conditions were hypoxic. Interestingly, for the used treatment temperatures, the intracellular HIF-1α accumulation in tumor cells seems to play a role in MAPK/ERK activation and mediator secretion (e.g., VEGF, PDGF-AA, Angiopoietin-2), as shown by inhibition experiments. Taken together, the hyperthermia of pancreatic adenocarcinoma cells in vitro impacts endothelial cells under defined environmental conditions (cell-to-cell contact, oxygen status, treatment temperature), whereby HIF-1α and VEGF secretion play a role in a complex context. Our observations could be exploited for the hyperthermic treatment of pancreatic cancer in the future.

Cellular metabolic adaptations in rheumatoid arthritis and their therapeutic implications

Activation of endothelium and immune cells is fundamental to the initiation of autoimmune diseases such as rheumatoid arthritis (RA), and it results in trans-endothelial cell migration and synovial fibroblast proliferation, leading to joint destruction. In RA, the synovial microvasculature is highly dysregulated, resulting in inefficient oxygen perfusion to the synovium, which, along with the high metabolic demands of activated immune and stromal cells, leads to a profoundly hypoxic microenvironment. In inflamed joints, infiltrating immune cells and synovial resident cells have great requirements for energy and nutrients, and they adapt their metabolic profiles to generate sufficient energy to support their highly activated inflammatory states. This shift in metabolic capacity of synovial cells enables them to produce the essential building blocks to support their proliferation, activation and invasiveness. Furthermore, it results in the accumulation of metabolic intermediates and alteration of redox-sensitive pathways, affecting signalling pathways that further potentiate the inflammatory response. Importantly, the inflamed synovium is a multicellular tissue, with cells differing in their metabolic requirements depending on complex cell-cell interactions, nutrient supply, metabolic intermediates and transcriptional regulation. Therefore, understanding the complex interplay between metabolic and inflammatory pathways in synovial cells in RA will provide insight into the underlying mechanisms of disease pathogenesis.

Macrophages and Cardiovascular Health

Research during the last decade has generated numerous insights on the presence, phenotype, and function of myeloid cells in cardiovascular organs. Newer tools with improved detection sensitivities revealed sizable populations of tissue-resident macrophages in all major healthy tissues. The heart and blood vessels contain robust numbers of these cells; for instance, 8% of noncardiomyocytes in the heart are macrophages. This number and the cell's phenotype change dramatically in disease conditions. While steady-state macrophages are mostly monocyte independent, macrophages residing in the inflamed vascular wall and the diseased heart derive from hematopoietic organs. In this review, we will highlight signals that regulate macrophage supply and function, imaging applications that can detect changes in cell numbers and phenotype, and opportunities to modulate cardiovascular inflammation by targeting macrophage biology. We strive to provide a systems-wide picture, i.e., to focus not only on cardiovascular organs but also on tissues involved in regulating cell supply and phenotype, as well as comorbidities that promote cardiovascular disease. We will summarize current developments at the intersection of immunology, detection technology, and cardiovascular health.

Oxygen ultra-fine bubbles water administration prevents bone loss of glucocorticoid-induced osteoporosis in mice by suppressing osteoclast differentiation

Oxygen ultra-fine bubbles (OUB) saline injection prevents bone loss of glucocorti\coid-induced osteoporosis in mice, and OUB inhibit osteoclastogenesis via RANK-TRAF6-c-Fos-NFATc1 signaling and RANK-p38 MAPK signaling in vitro.

INTRODUCTION

Ultra-fine bubbles (<200 nm in diameter) have several unique properties, and they are tested in various medical fields. The purpose of this study was to investigate the effects of oxygen ultra-fine bubbles (OUB) on glucocorticoid-induced osteoporosis (GIO) model mice.

METHODS

Prednisolone (PSL, 5 mg) was subcutaneously inserted in 6-month-old male C57BL/6J mice, and 200 μl of saline, OUB-diluted saline, or nitrogen ultra-fine bubbles (NUB)-diluted saline was intraperitoneally injected three times per week for 8 weeks the day after operations. Mice were divided into four groups; (1) control, sham-operation + saline; (2) GIO, PSL + saline; (3) GIO + OUB, PSL + OUB saline; (4) GIO + NUB, PSL + NUB saline. The effects of OUB on osteoblasts and osteoclasts were examined by serially diluted OUB medium in vitro.

RESULTS

Bone mass was significantly decreased in GIO [bone volume/total volume (%): control vs. GIO 12.6 vs. 7.9; p < 0.01] while significantly preserved in GIO + OUB (GIO vs. GIO + OUB 7.9 vs. 12.9; p < 0.05). In addition, tartrate-resistant acid phosphatase (TRAP)-positive cells in the distal femur [mean osteoclasts number/bone surface (mm^-1)] was significantly increased in GIO (control vs. GIO 6.8 vs. 11.6; p < 0.01) while suppressed in GIO + OUB (GIO vs. GIO + OUB 11.6 vs. 7.5; p < 0.01). NUB did not affect these parameters. In vitro experiments revealed that OUB significantly inhibited osteoclastogenesis by inhibiting RANK-TRAF6-c-Fos-NFATc1 signaling, RANK-p38 MAPK signaling, and TRAP/Cathepsin K/DC-STAMP mRNA expression in a concentration-dependent manner. OUB did not affect osteoblastogenesis in vitro.

CONCLUSIONS

OUB prevent bone loss in GIO mice by inhibiting osteoclastogenesis.

Celastrol protects ischaemic myocardium through a heat shock response with up-regulation of haeme oxygenase-1

BACKGROUND AND PURPOSE

Celastrol, a triterpene from plants, has been used in traditional oriental medicine to treat various diseases. Here, we investigated the cardioprotective effects of celastrol against ischaemia.

EXPERIMENTAL APPROACH

Protective pathways induced by celastrol were investigated in hypoxic cultures of H9c2 rat cardiomyoblasts and in a rat model of myocardial infarction, assessed with echocardiographic and histological analysis.

KEY RESULTS

In H9c2 cells, celastrol triggered reactive oxygen species (ROS) formation within minutes, induced nuclear translocation of the transcription factor heat shock factor 1 (HSF1) resulting in a heat shock response (HSR) leading to increased expression of heat shock proteins (HSPs). ROS scavenger N-acetylcysteine reduced expression of HSP70 and HSP32 (haeme oxygenase-1, HO-1). Celastrol improved H9c2 survival under hypoxic stress, and functional analysis revealed HSF1 and HO-1 as key effectors of the HSR, induced by celastrol, in promoting cytoprotection. In the rat ischaemic myocardium, celastrol treatment improved cardiac function and reduced adverse left ventricular remodelling at 14 days. Celastrol triggered expression of cardioprotective HO-1 and inhibited fibrosis and infarct size. In the peri-infarct area, celastrol reduced myofibroblast and macrophage infiltration, while attenuating up-regulation of TGF-β and collagen genes.

CONCLUSIONS AND IMPLICATIONS

Celastrol treatment induced an HSR through activation of HSF1 with up-regulation of HO-1 as the key effector, promoting cardiomyocyte survival, reduction of injury and adverse remodelling with preservation of cardiac function. Celastrol may represent a novel potent pharmacological cardioprotective agent mimicking ischaemic conditioning that could have a valuable impact in the treatment of myocardial infarction.

mTOR- and HIF-1α-mediated aerobic glycolysis as metabolic basis for trained immunity

Epigenetic reprogramming of myeloid cells, also known as trained immunity, confers nonspecific protection from secondary infections. Using histone modification profiles of human monocytes trained with the Candida albicans cell wall constituent β-glucan, together with a genome-wide transcriptome, we identified the induced expression of genes involved in glucose metabolism. Trained monocytes display high glucose consumption, high lactate production, and a high ratio of nicotinamide adenine dinucleotide (NAD(+)) to its reduced form (NADH), reflecting a shift in metabolism with an increase in glycolysis dependent on the activation of mammalian target of rapamycin (mTOR) through a dectin-1-Akt-HIF-1α (hypoxia-inducible factor-1α) pathway. Inhibition of Akt, mTOR, or HIF-1α blocked monocyte induction of trained immunity, whereas the adenosine monophosphate-activated protein kinase activator metformin inhibited the innate immune response to fungal infection. Mice with a myeloid cell-specific defect in HIF-1α were unable to mount trained immunity against bacterial sepsis. Our results indicate that induction of aerobic glycolysis through an Akt-mTOR-HIF-1α pathway represents the metabolic basis of trained immunity.

The metabolic cooperation between cells in solid cancer tumors

Cancer cells cooperate with stromal cells and use their environment to promote tumor growth. Energy production depends on nutrient availability and O₂ concentration. Well-oxygenated cells are highly proliferative and reorient the glucose metabolism towards biosynthesis, whereas glutamine oxidation replenishes the TCA cycle coupled with OXPHOS-ATP production. Glucose, glutamine and alanine transformations sustain nucleotide and fatty acid synthesis. In contrast, hypoxic cells slow down their proliferation, enhance glycolysis to produce ATP and reject lactate which is recycled as fuel by normoxic cells. Thus, glucose is spared for biosynthesis and/or for hypoxic cell function. Environmental cells, such as fibroblasts and adipocytes, serve as food donors for cancer cells, which reject waste products (CO₂ , H⁺, ammoniac, polyamines…) promoting EMT, invasion, angiogenesis and proliferation. This metabolic-coupling can be considered as a form of commensalism whereby non-malignant cells support the growth of cancer cells. Understanding these cellular cooperations within tumors may be a source of inspiration to develop new anti-cancer agents.

Positive correlation of STAT1 and miR-146a with anemia in patients with systemic lupus erythematosus

PURPOSE

Anemia is one of the most common hematological manifestations in SLE patients, occurring in about 50% of active cases. STAT1 is a critical signaling molecule required for the production of type-1 interferon (I-IFN), CCL2, and CXCL10, all of which are upregulated in SLE. Overexpression of STAT1 has been described to be involved in anemia in animal models. The aim of this study is to analyze how these components are involved in SLE-associated anemia.

METHODS

Blood samples were collected from 39 healthy donors and 101 SLE patients fulfilling ACR criteria. Samples were collected from a total of 180 visits (58 patients had 2 or more visits) of which 52 visits included a diagnosis of anemia. Healthy donors had only single visit. Total RNA, isolated from leukocytes, was analyzed by Taqman qPCR. Relative expression levels of I-IFN signature genes, chemokines, and miR-146a were determined by the ΔΔCT method. Results were correlated with clinical data and analyzed by the Wilcoxon/Kruskal-Wallis test and Fisher's exact test.

RESULTS

Significant increases in IFN score (p < 0.0001), STAT1 (p < 0.0001), miR-146a (p < 0.0005), CCL2 (p = 0.0047), and CXCL10 (p = 0.017), as well as a significant decrease in pri-miR-146a (p = 0.0002), were detected in the anemic SLE patient visits (n = 52) compared to non-anemic SLE visits (n = 128). Regardless of disease activity, lupus nephritis, or race, anemic SLE patients displayed significantly elevated levels of STAT1 and miR-146a compared to non-anemic SLE patients.

CONCLUSIONS

STAT1 and miR-146a may be upregulated during inflammation and via proinflammatory cytokines and chemokines in SLE. Prolonged upregulation of STAT1 and miR-146a appears to play an important role in anemia in SLE patients.

Tumor hypoxia does not drive differentiation of tumor-associated macrophages but rather fine-tunes the M2-like macrophage population

Tumor-associated macrophages (TAM) are exposed to multiple microenvironmental cues in tumors, which collaborate to endow these cells with protumoral activities. Hypoxia, caused by an imbalance in oxygen supply and demand because of a poorly organized vasculature, is often a prominent feature in solid tumors. However, to what extent tumor hypoxia regulates the TAM phenotype in vivo is unknown. Here, we show that the myeloid infiltrate in mouse lung carcinoma tumors encompasses two morphologically distinct CD11b(hi)F4/80(hi)Ly6C(lo) TAM subsets, designated as MHC-II(lo) and MHC-II(hi) TAM, both of which were derived from tumor-infiltrating Ly6C(hi) monocytes. MHC-II(lo) TAM express higher levels of prototypical M2 markers and reside in more hypoxic regions. Consequently, MHC-II(lo) TAM contain higher mRNA levels for hypoxia-regulated genes than their MHC-II(hi) counterparts. To assess the in vivo role of hypoxia on these TAM features, cancer cells were inoculated in prolyl hydroxylase domain 2 (PHD2)-haplodeficient mice, resulting in better-oxygenated tumors. Interestingly, reduced tumor hypoxia did not alter the relative abundance of TAM subsets nor their M2 marker expression, but specifically lowered hypoxia-sensitive gene expression and angiogenic activity in the MHC-II(lo) TAM subset. The same observation in PHD2(+/+) → PHD2(+/-) bone marrow chimeras also suggests organization of a better-oxygenized microenvironment. Together, our results show that hypoxia is not a major driver of TAM subset differentiation, but rather specifically fine-tunes the phenotype of M2-like MHC-II(lo) TAM.