Biomedical subjects

Ariadne Androulidaki

Publications and source records attributed to Ariadne Androulidaki.

10 recordsLinked to original sources

PubMed2026

A targetable dependency on nonsense-mediated decay for cellular homeostasis and immune control in small cell lung cancer.

Small cell lung cancer (SCLC) is one of the most aggressive malignancies, characterized by rapid metastatic dissemination and poor overall survival. Despite harboring excessive alterations, expectedly resulting in immunogenic neoantigens, patients with SCLC remain largely refractory to immunotherapy. We found abundant frameshift mutations in SCLC, regarded as highly immunogenic, counterbalanced by a hyperactive nonsense-mediated decay (NMD) pathway, responsible for frameshift-mRNA degradation. NMD activity correlated with tumor mutational burden (TMB) across cancers, suggesting that SCLC and other TMBhigh cancers may depend on NMD to limit the accumulation of mutation-derived byproducts in order to maintain cellular homeostasis and evade immune recognition. In TMBhigh SCLC models, inhibition of NMD impaired cell proliferation and induced ER stress-dependent apoptosis due to the accumulation of misfolded proteins. Genetic and pharmacological NMD inhibition in vivo effectively controlled TMBhigh tumor growth without overt toxicity. By integrating genome and transcriptome sequencing with MHC-I immunopeptidomics and functional in vitro and in vivo assays, we identified that NMD inhibition boosted neoantigen expression and presentation by tumor cells and increased T cell recognition, thus enhancing overall tumor immunogenicity and further improving immunotherapy efficacy in vivo. Our work shows that SCLC - as a TMBhigh cancer - relies on NMD for survival and immune escape, uncovering a novel TMB-dependent tractable vulnerability for this devastating disease.

Humans↗

PubMed2025

An atlas of ferroptosis-induced secretomes.

Cells undergoing regulated necrosis systemically communicate with the immune system via the release of protein and non-protein secretomes. Ferroptosis is a recently described iron-dependent type of regulated necrosis driven by massive lipid peroxidation. While membrane rupture occurs during ferroptosis, a comprehensive appraisal of ferroptotic secretomes and their potential biological activity has been lacking. Here, we apply a multi-omics approach to provide an atlas of ferroptosis-induced secretomes and reveal a novel function in macrophage priming. Proteins with assigned DAMP and innate immune system function, such as MIF, heat shock proteins (HSPs), and chaperones, were released from ferroptotic cells. Non-protein secretomes with assigned inflammatory function contained oxylipins as well as TCA- and methionine-cycle metabolites. Interestingly, incubation of bone marrow-derived macrophages (BMDMs) with ferroptotic supernatants induced transcriptional reprogramming consistent with priming. Indeed, exposure to ferroptotic supernatants enhanced LPS-induced cytokine production. These results define a catalog of ferroptosis-induced secretomes and identify a biological activity in macrophage priming with important implications for the fine-tuning of inflammatory processes.

Ferroptosis↗

PubMed2007

Corticotropin releasing factor receptor 1 (CRF1) and CRF2 agonists exert an anti-inflammatory effect during the early phase of inflammation suppressing LPS-induced TNF-alpha release from macrophages via induction of COX-2 and PGE2.

Corticotropin-releasing factor (CRF), the principal regulator of the hypothalamus-pituitary-adrenal (HPA) axis, also modulates the inflammatory response directly, via its effect on mast cells and macrophages. On macrophages, it augments production of lipopolysaccharide (LPS)-induced pro-inflammatory cytokines. CRF and its related peptides may also act as anti-inflammatory agents. Aim of the present work was to examine the role of macrophages on the anti-inflammatory effects of CRF-peptides and the mechanism involved. Thus, we examined if CRF receptor 1 (CRF1) and CRF2 agonists exert any anti-inflammatory effect on primary mouse macrophages. We have found that: (a) CRF, Urocortin (UCN)1 and UCN2 transiently suppressed the release of Tumor Necrosis Factor-alpha (TNF-alpha) in LPS-activated macrophages, an effect peaking at 4 h. This effect did not involve changes on TNF-alpha transcription. (b) CRF peptide-induced suppression of TNF-alpha release depended on induction of COX-2 and PGE2 synthesis. (c) Use of specific CRF1 and CRF2 antagonists suggested that this effect involved both CRF receptor types. (d) The effect of CRF-peptides on COX-2 was mediated via PI3K and p38MAPK. (e) Longer exposure of macrophages to CRF-peptides resulted in induction of TNF-alpha production via enhancement of its transcription. In conclusion, this is the first report suggesting that CRF1 and CRF2 agonists exert a biphasic effect on macrophages. During the early stages of the inflammatory response, they suppress TNF-alpha release via induction of COX-2/PGE2 while later on they induce TNF-alpha transcription. Hence, the reported anti-inflammatory effect of CRF-peptides appears to involve macrophages and is confined at the early stage of inflammation.

Animals↗

PubMed2006

Neuropeptide urocortin and its receptors are expressed in rat Kupffer cells.

The stress neuropeptides, corticotropin-releasing hormone (CRH) and urocortin (UCN), modulate the inflammatory response via the hypothalamus-pituitary-adrenal axis and locally, in a paracrine manner, act on mast and macrophage cells. Kupffer cells (KCs) are the resident macrophages of the liver. They represent the bulk of tissue macrophages in the body and they are the first to face invading noxious agents reaching the body via the portal circulation. The aim of the present report was to study the expression of the CRH system in rat KC and test its functionality. Our findings are as follows: (1) In highly purified KCs the transcripts of UCN, of its receptors CRHR1, CRHR2 and that of the pseudoreceptor CRH-binding protein (CRHBP) were present while that of CRH was not detectable. (2) Similarly, immunoreactive UCN, CRHR1, CRHR2 and CRHBP were easily detectable by immunohistochemistry and immunofluorescence in sections of whole rat liver (localized in KC) as well as in purified KC while CRH was again not detectable. (3) Exposure of purified KC to CRH or UCN suppressed lipopolysaccharide-induced tumor necrosis factor alpha production, an effect completely prevented by the CRHR1 and CRHR2 receptor antagonist astressin. Our data demonstrate the presence of UCN and its receptors in rat KC, the absence of CRH, and the functionality of these receptors. We propose that a UCN-based system may affect local inflammatory phenomena in the liver acting in a paracrine manner.

Animals↗

PubMed2006

Signalling networks regulating cyclooxygenase-2.

Cyclooxygenease-2 (COX-2) is the key enzyme regulating the production of prostaglandins, central mediators of inflammation. The expression of cyclooxygenease-2 is induced by several extra cellular signals including pro-inflammatory and growth-promoting stimuli. All signals converge to the activation of mitogen-activated protein kinases (MAPK) that regulate cyclooxygenease-2 mRNA levels both at the transcriptional and post-transcriptional level. The machinery appears to be highly specialized involving activation of distinct signalling molecules depending on the type of extracellular stimulus. Expression of cyclooxygenease-2 mRNA is regulated by several transcription factors including the cyclic-AMP response element binding protein (CREB), nuclear factor kappa B (NFkB) and the CCAAT-enhancer binding protein (C/EBP). Cyclooxygenease-2 is also affected post-transcriptionaly, at the level of mRNA stability. Finally, cyclooxygenease-2 can be affected directly at its enzymatic activity by nitric oxide and nitric oxide synthase (iNOS). Each step of cyclooxygenease-2 regulation can be used as potential therapeutic target.

Animals↗

PubMed2006

Corticotropin-releasing factor and the urocortins induce the expression of TLR4 in macrophages via activation of the transcription factors PU.1 and AP-1.

Corticotropin-releasing factor (CRF) augments LPS-induced proinflammatory cytokine production from macrophages. The aim of the present study was to determine the mechanism by which CRF and its related peptides urocortins (UCN) 1 and 2 affect LPS-induced cytokine production. We examined their role on TLR4 expression, the signal-transducing receptor of LPS. For this purpose, the murine macrophage cell line RAW 264.7 and primary murine peritoneal macrophages were used. Exposure of peritoneal macrophages and RAW 264.7 cells to CRF, UCN1, or UCN2 up-regulated TLR4 mRNA and protein levels. To study whether that effect occurred at the transcriptional level, RAW 264.7 cells were transfected with a construct containing the proximal region of the TLR4 promoter linked to the luciferase gene. CRF peptides induced activation of the TLR4 promoter, an effect abolished upon mutation of a proximal PU.1-binding consensus or upon mutation of an AP-1-binding element. Indeed, all three peptides promoted PU.1 binding to the proximal PU.1 site and increased DNA-binding activity to the AP-1 site. The effects of CRF peptides were inhibited by the CRF2 antagonist anti-sauvagine-30, but not by the CRF1 antagonist antalarmin, suggesting that CRF peptides mediated the up-regulation of TLR4 via the CRF2 receptor. Finally, CRF peptides blocked the inhibitory effect of LPS on TLR4 expression. In conclusion, our data suggest that CRF peptides play an important role on macrophage function. They augment the effect of LPS by inducing Tlr4 gene expression, through CRF2, via activation of the transcription factors PU.1 and AP-1.

Animals↗

PubMed2006

Peripheral factors in the metabolic syndrome: the pivotal role of adiponectin.

Several recently published reports, including ours, suggest that adiponectin is a strong proinflammatory agent. Indeed, exposure of human placenta and adipose tissue to adiponectin induces the production of interleukin-1beta (IL-1beta), IL-6, tumor necrosis factor alpha (TNF-alpha), and prostaglandin E2 (PGE2). We have previously shown that adiponectin is a powerful inducer of proinflammatory cytokines production by macrophages. The reported anti-inflammatory effect of adiponectin may be due to the induction of macrophage tolerance to further adiponectin exposure or to other proinflammatory stimuli including the Toll-like receptor (TLR) 3 ligand polyI:C and the TLR4 ligand lipopolysaccharide (LPS). We now present additional data supporting the hypothesis that adiponectin is a strong proinflammatory adipokine. More specifically, we demonstrate that adiponectin induces IL-1beta and IL-8 from THP-1 macrophage cell line. The effect of adiponectin is not restricted to differentiated THP-1 macrophages but it is evident at lower levels in undifferentiated THP-1 monocytes promoting TNF-alpha, IL-6, and IL-8 production. Thus, its high levels in the circulation of lean subjects render their macrophages resistant to several proinflammatory stimuli including its own thus acting in effect as an anti-inflammatory agent. Lowering of its high levels, as a consequence of increased body mass index (BMI), renders macrophages sensitive to any proinflammatory insult.

Adiponectin↗

PubMed2005

Adiponectin induces TNF-alpha and IL-6 in macrophages and promotes tolerance to itself and other pro-inflammatory stimuli.

Adiponectin exerts anti-inflammatory effects via macrophages, suppressing the production of pro-inflammatory cytokines in response to bacterial lipopolysaccharide (LPS). Here, we provide experimental evidence that the "anti-inflammatory" effect of adiponectin may be due to an induction of macrophage tolerance: globular adiponectin (gAd) is a powerful inducer of TNF-alpha and IL-6 secretion in primary human peripheral macrophages, in the THP-1 human macrophage cell line, and in primary mouse peritoneal macrophages. Pre-exposure of macrophages to 10 microg/ml gAd rendered them tolerant to further gAd exposure or to other pro-inflammatory stimuli such as TLR3 ligand polyI:C and TLR4 ligand LPS, while pre-exposure to 1 microg/ml of and re-exposure to 10 microg/ml gAd unmasked its pro-inflammatory properties. GAd induced NF-kappaB activation and tolerance to further gAd or LPS exposure. Our data suggest that adiponectin constant presence in the circulation in high levels (in lean subjects) renders macrophages resistant to pro-inflammatory stimuli, including its own.

Adiponectin↗

PubMed2005

Urocortin 1 and Urocortin 2 induce macrophage apoptosis via CRFR2.

Macrophages undergo apoptosis as a mechanism of regulating their activation and the inflammatory reaction. Macrophages express the Corticotropin-Releasing Factor Receptor-2 (CRFR2) the endogenous agonists of which, the urocortins, are also present at the site of inflammation. We have found that urocortins induced macrophage apoptosis in a dose- and time-dependent manner via CRFR2. In contrast to lipopolysaccharide (LPS)-induced apoptosis, the pro-apoptosis pathway activated by urocortins involved the pro-apoptotic Bax and Bad proteins and not nitric oxide, JNK and p38MAPK characteristic of LPS. In conclusion, our data suggest that endogenous CRFR2 ligands exert an anti-inflammatory effect via induction of macrophage apoptosis.

Animals↗

PubMed2005

Corticotropin-releasing hormone activates protein kinase C in an isoenzyme-specific manner.

Protein kinase C (PKC) has recently emerged as mediator of corticotropin-releasing hormone (CRH) effects. Aim of the present study was to study the effects of CRH on each PKC isoenzyme. As a model we have used the PC12 rat pheochromocytoma cell line, expressing the CRH type 1 receptor (CRHR1). Our data were as follows: (a) CRH-induced rapid phosphorylation of conventional PKCalpha and PKCbeta, accompanied by parallel increase of their concentration within nucleus. (b) CRH suppressed the phosphorylation of novel PKCdelta and PKCtheta;, which remained in the cytosol. (c) CRH-induced transient phosphorylation of atypical PKClambda and had no effect on PKCmu. (d) The effect of CRH on each PKC isoenzyme was blocked by a CRHR1 antagonist. (e) Blockade of conventional PKC phosphorylation inhibited CRH-induced calcium ion mobilization from intracellular stores as well as the CRH-induced apoptosis and Fas ligand production. In conclusion, our findings suggest that CRH via its CRHR1 receptor differentially regulates PKC-isoenzyme phosphorylation, an apparently physiologically relevant effect since blockade of conventional PKC phosphorylation abolished the biological effect of CRH.

Animals↗