Editorial: The intricate innate immune-cancer cell relationship in the context of tumor angiogenesis, immunity and microbiota: The angiogenic switch in the tumor microenvironment as a key target for immunotherapies

The intricate innate immune-cancer cell relationship in the context of tumor angiogenesis, immunity and microbiota: The angiogenic switch in the tumor microenvironment as a key target for immunotherapie

Activation of Notch signalling by soluble Dll4 decreases vascular permeability via a cAMP/PKA-dependent pathway

© 2019 the American Physiological Society. The Notch ligand delta-like ligand 4 (Dll4), upregulated by VEGF, is a key regulator of vessel morphogenesis and function, controlling tip and stalk cell selection during sprouting angiogenesis. Inhibition of Dll4 results in hypersprouting, nonfunctional, poorly perfused vessels, suggesting a role for Dll4 in the formation of mature, reactive, functional vessels, with low permeability and able to restrict fluid and solute exchange. We tested the hypothesis that Dll4 controls transvascular fluid exchange. A recombinant protein expressing only the extracellular portion of Dll4 [soluble Dll4 (sDll4)] induced Notch signaling in endothelial cells (ECs), resulting in increased expression of vascular-endothelial cadherin, but not the tight junctional protein zonula occludens 1, at intercellular junctions. sDll4 decreased the permeability of FITC-labeled albumin across EC monolayers, and this effect was abrogated by coculture with the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester. One of the known molecular effectors responsible for strengthening EC-EC contacts is PKA, so we tested the effect of modulation of PKA on the sDll4-mediated reduction of permeability. Inhibition of PKA reversed the sDll4-mediated reduction in permeability and reduced expression of the Notch target gene Hey1. Knockdown of PKA reduced sDLL4-mediated vascular-endothelial cadherin junctional expression. sDll4 also caused a significant decrease in the hydraulic conductivity of rat mesenteric microvessels in vivo. This reduction was abolished upon coperfusion with the PKA inhibitor H89 dihydrochloride. These results indicate that Dll4 signaling through Notch activation acts through a cAMP/PKA pathway upon intercellular adherens junctions, but not tight junctions, to regulate endothelial barrier function. NEW & NOTEWORTHY Notch signaling reduces vascular permeability through stimulation of cAMP-dependent protein kinase A

Licensed human natural killer cells aid dendritic cell maturation via TNFSF14/LIGHT

Interactions between natural killer (NK) cells and dendritic cells (DC) aid DC maturation and promote T cell responses. Here, we have analysed the response of human NK cells to tumor cells and we identify a pathway by which NK-DC interactions occur. Gene expression profiling of tumor-responsive NK cells identified the very rapid induction of TNFSF14 (also known as LIGHT), a cytokine implicated in the enhancement of anti-tumor responses. TNFSF14 protein expression was induced by three primary mechanisms of NK cell activation, namely via the engagement of CD16, by the synergistic activity of multiple target cell-sensing NK cell activation receptors and by the cytokines IL-2 and IL-15. For anti-tumor responses, TNFSF14 was preferentially produced by the licensed NK cell population, defined by the expression of inhibitory receptors specific for self-MHC class I molecules. In contrast, IL-2 and IL-15 treatment induced TNFSF14 production by both licensed and unlicensed NK cells, reflecting the ability of pro-inflammatory conditions to override the licensing mechanism. Importantly, both tumor and cytokine activated NK cells induced DC maturation in a TNFSF14-dependent manner. The coupling of TNFSF14 production to tumor-sensing NK cell activation receptors links the tumor immune surveillance function of NK cells to DC maturation and adaptive immunity. Furthermore, regulation by NK cell licensing helps to safeguard against TNFSF14 production in response to healthy tissues

Enhanced notch signaling modulates unproductive revascularization in response to nitric oxide-angiopoietin signaling in a mouse model of peripheral ischemia

IntroductionArteriolargenesis can be induced by concomitant stimulation of nitric Oxide (NO)‐Angiopoietin receptor (Tie)‐Vascular Endothelial Growth Factor (VEGF) signaling in the rat mesentery angiogenesis assay. We hypothesized that the same combination of exogenously added growth factors would also have a positive impact on arteriolargenesis and, consequently, the recovery of blood flow in a model of unilateral hindlimb ischemia.Results and MethodsNO‐Tie mice had faster blood flow recovery compared to control mice, as assessed by laser speckle imaging. There was no change in capillary density within the ischemic muscles, but arteriole density was higher in NO‐Tie mice. Given the previously documented beneficial effect of VEGF signaling, we tested whether NO‐Tie‐VEGF mice would show further improvement. Surprisingly, these mice recovered no differently from control, arteriole density was similar and capillary density was lower. Dll4 is a driver of arterial specification, so we hypothesized that Notch1 expression would be involved in arteriolargenesis. There was a significant upregulation of Notch1 transcripts in NO‐Tie‐VEGF compared with NO‐Tie mice. Using soluble Dll4 (sDll4), we stimulated Notch signaling in the ischemic muscles of mice. NO‐Tie‐sDll4 mice had significantly increased capillary and arteriole densities, but impaired blood flow recovery.ConclusionThese results suggest that Dll4 activation early on in revascularization can lead to unproductive angiogenesis and arteriolargenesis, despite increased vascular densities. These results suggest spatial and temporal balance of growth factors needs to be perfected for ideal functional and anatomical revascularisation

Direct RT-qPCR Assay for the Detection of SARS-CoV-2 in Saliva Samples

Since mid-2020 there have been complexities and difficulties in the standardisation and administration of nasopharyngeal swabs. Coupled with the variable and/or poor accuracy of lateral flow devices, this has led to increased societal ‘testing fatigue’ and reduced confidence in test results. Consequently, asymptomatic individuals have developed reluctance towards repeat testing, which remains the best way to monitor COVID-19 cases in the wider population. On the other hand, saliva-based PCR, a non-invasive, highly sensitive, and accurate test suitable for everyone, is gaining momentum as a straightforward and reliable means of detecting SARS-CoV-2 in symptomatic and asymptomatic individuals. Here, we provide an itemised list of the equipment and reagents involved in the process of sample submission, inactivation and analysis, as well as a detailed description of how each of these steps is performed

Performance evaluation of a non-invasive one-step multiplex RT-qPCR assay for detection of SARS-CoV-2 direct from saliva

Polymerase chain reaction (PCR) has proven to be the gold-standard for SARS-CoV-2 detection in clinical settings. The most common approaches rely on nasopharyngeal specimens obtained from swabs, followed by RNA extraction, reverse transcription and quantitative PCR. Although swab-based PCR is sensitive, swabbing is invasive and unpleasant to administer, reducing patient compliance for regular testing and resulting in an increased risk of improper sampling. To overcome these obstacles, we developed a non-invasive one-step RT-qPCR assay performed directly on saliva specimens. The University of Nottingham Asymptomatic Testing Service protocol simplifies sample collection and bypasses the need for RNA extraction, or additives, thus helping to encourage more regular testing and reducing processing time and costs. We have evaluated the assay against the performance criteria specified by the UK regulatory bodies and attained accreditation (BS EN ISO/IEC 17,025:2017) for SARS-CoV-2 diagnostic testing by the United Kingdom Accreditation Service. We observed a sensitivity of 1 viral copy per microlitre of saliva, and demonstrated a concordance of > 99.4% between our results and those of other accredited testing facilities. We concluded that saliva is a stable medium that allows for a highly precise, repeatable, and robust testing method

Can the co-dependence of the immune system and angiogenesis facilitate pharmacological targeting of tumours?

Tumours elicit a number of mechanisms to induce a reprogramming of innate and adaptive immune cells to their advantage, inducing a pro-angiogenic phenotype. Investigation of these events is now leading to the identification of specific myeloid and lymphoid cell-targeted therapies, as well as of unexplored off-target activities of clinically relevant chemotherapeutic and metabolic drugs. It is also leading to an enhanced understanding of the interplay between angiogenesis and the immune system, and the value of novel co-targeting approaches using both immunotherapy and anti-angiogenic therapy. Here, we review recently identified mechanisms and potential pharmacological approaches targeting the crosstalk between cancer cells and the host immune system, providing an overview on novel therapeutic opportunities linking immuno-oncology and anti-angiogenic therapy