Combining Antivirals and Immunomodulators to Fight COVID-19.

The majority of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected individuals remain paucisymptomatic, contrasting with a minority of infected individuals in danger of death. Here, we speculate that the robust disease resistance of most individuals is due to a swift production of type I interferon (IFNα/ß), presumably sufficient to lower the viremia. A minority of infected individuals with a preexisting chronic inflammatory state fail to mount this early efficient response, leading to a delayed harmful inflammatory response. To improve the epidemiological scenario, we propose combining: (i) the development of efficient antivirals administered early enough to assist in the production of endogenous IFNα/ß; (ii) potentiating early IFN responses; (iii) administering anti-inflammatory treatments when needed, but not too early to interfere with endogenous antiviral responses.

T cell adhesion primes antigen receptor-induced calcium responses through a transient rise in adenosine 3',5'-cyclic monophosphate.

It is well established that sustained increases in cyclic AMP (cAMP) such as those triggered by forskolin inhibit T cell activation. We describe here an unexpected phenomenon: in T cells, a transient cAMP increase triggered by the interaction with a dendritic cell strongly potentiates T cell receptor (TCR) signaling. We discovered this effect by examining the molecular basis of the adhesion-dependent sensitization of T cells. T cell adhesion caused extracellular-signal-regulated kinase (ERK) activation, which was necessary for the sensitization process. T cell sensitization could be mimicked in suspended cells by the uncaging of caged cAMP upon ultraviolet illumination. Calcium responses occurring in T cells upon interaction with dendritic cells were strongly inhibited when protein kinase A activation was blocked. Thus, whereas sustained cAMP increases are well known to inhibit TCR signaling, transient cAMP increases occurring physiologically upon formation of an immunological synapse facilitate antigen detection.

CCR7 ligands control basal T cell motility within lymph node slices in a phosphoinositide 3-kinase-independent manner.

The molecular mechanisms responsible for the sustained basal motility of T cells within lymph nodes (LNs) remain elusive. To study T cell motility in a LN environment, we have developed a new experimental system based on slices of LNs that allows the assessment of T cell trafficking after adoptive transfer or direct addition of T cells to the slice. Using this experimental system, we show that T cell motility is highly sensitive to pertussis toxin and strongly depends on CCR7 and its ligands. Our results also demonstrate that, despite its established role in myeloid cell locomotion, phosphoinositide 3-kinase (PI3K) activity does not contribute to the exploratory behavior of the T lymphocytes within LN slices. Likewise, although PI3K activation is detectable in chemokine-treated T cells, PI3K plays only a minor role in T cell polarization and migration in vitro. Collectively, our results suggest that the common amplification system that, in other cells, facilitates large phosphatidylinositol 3,4,5-trisphosphate increases at the plasma membrane is absent in T cells. We conclude that T cell motility within LNs is not an intrinsic property of T lymphocytes but is driven in a PI3K-independent manner by the lymphoid chemokine-rich environment.

[Preventable cancers: Is it enough to change our behaviour?] / Cancers évitables - Suffit-il de changer nos comportements ?

In France, part of 40 % of preventable cancers can be attributed to lifestyle habits. Epidemiological data show that occupational exposures are a major cause of these cancers. However, despite this evidence, the prevention actions promoted by public authorities are focused on changing individual behaviors. In this article, we seek to understand the reasons of the erasure of the role of socio-environmental factors in cancer prevention discourse.

Title: Cancers évitables - Suffit-il de changer nos comportements ? Abstract: En France, une partie des 40 % de cancers évitables peut être attribuée aux habitudes de vie. Les données épidémiologiques révèlent que les expositions professionnelles et domestiques à des substances cancérogènes sont aussi responsables d'une fraction significative de ces cancers. Pourtant, en dépit de ces évidences, les actions de prévention promues par les pouvoirs publics se focalisent sur le changement des comportements individuels. Dans cet article, nous cherchons à comprendre les raisons de l'effacement de la place des facteurs socio-environnementaux des discours portant sur la prévention des cancers.

[Mechanisms underlying chronic fatigue, a symptom too often overlooked]. / La fatigue chronique, un symptôme trop souvent négligé - I. Une immunité dérégulée à son origine ?

Acute fatigue after exertion, like acute inflammation after injury, is useful for our body. On the contrary, both chronic fatigue and chronic inflammation are deleterious, and they are associated in many diseases. In this first part, we will analyze different immune phenomena (bystander activation, memory of the innate immune system, link with the intestinal microbiota) involved in triggering chronic inflammation. This review aims at looking for links between different signs and symptoms associated with chronic fatigue, as well as between different diseases in which severe chronic fatigue can manifest. Possible underlying mechanisms for these phenomena are discussed. This is a proposal made by a researcher, with no clinical experience, to doctors confronted with an entity that is still largely mysterious. The link between chronic inflammation, neuroinflammation and fatigue will be examined in a second part.

TITLE: La fatigue chronique, un symptôme trop souvent négligé - I. Une immunité dérégulée à son origine ? ABSTRACT: La fatigue aiguë après un effort, comme l'inflammation aiguë après une blessure, sont utiles à notre organisme. En revanche, la fatigue chronique, comme l'inflammation chronique, sont délétères, et elles sont associées dans de nombreuses maladies. Nous analyserons dans cette première partie différents phénomènes immunitaires impliqués dans le déclenchement de l'inflammation chronique. Cette revue vise à proposer des liens entre différents signes et symptômes associés à la fatigue chronique, ainsi qu'entre différentes maladies dans lesquelles peut se manifester une fatigue chronique grave. Des mécanismes possibles, sous-jacents à ces processus, et leurs liens, sont également discutés. Il s'agit ici d'une proposition faite par un chercheur, sans expérience clinique, à des médecins confrontés à une entité qui reste encore largement mystérieuse. L'articulation entre inflammation chronique, neuro-inflammation et fatigue, sera examinée dans une deuxième partie.

[Mechanisms underlying chronic fatigue, a symptom too often overlooked II- From deregulated immunity to neuroinflammation and its consequences]. / Mécanismes sous-jacents à la fatigue chronique, un symptôme trop souvent négligé - II. De l'immunité dérégulée à la neuroinflammation et ses conséquences.

Hypothalamus stimulation by inflammatory and / or stress signals can trigger activation of the HPA (hypothalamic-pituitary-adrenal) axis, which includes the hypothalamus, pituitary and adrenal gland. Acute activation of the HPA axis is fundamental for the fight or flight response. It allows a maximal energy mobilization available for an effort, whilst erasing fatigue. On the contrary, the chronic activation of this axis decreases muscle efficiency and leads to chronic fatigue. In this second part of our review will be discussed several strategic points that need to be considered for attempting to understand and treat together inflammation and chronic fatigue.

TITLE: Mécanismes sous-jacents à la fatigue chronique, un symptôme trop souvent négligé - II. De l'immunité dérégulée à la neuroinflammation et ses conséquences. ABSTRACT: L'activation de l'hypothalamus par des signaux inflammatoires et/ou de stress peut déclencher celle de l'axe HPA (hypothalamic-pituitary-adrenal axis), qui intègre l'hypothalamus, l'hypophyse et la glande surrénale. L'activation aiguë de l'axe HPA est fondamentale pour la réponse fight or flight (« combats ou fuis ¼). Elle permet de mobiliser un maximum d'énergie pour un effort, tout en effaçant la fatigue. En revanche, son activation chronique diminue l'efficacité musculaire et entraîne une fatigue chronique. On discutera dans cette partie de plusieurs points stratégiques à considérer pour tenter de comprendre et de traiter ensemble inflammation et fatigue chroniques.

CAR T-cell Entry into Tumor Islets Is a Two-Step Process Dependent on IFNγ and ICAM-1.

Adoptive transfer of T cells expressing chimeric antigen receptors (CAR) has shown remarkable clinical efficacy against advanced B-cell malignancies but not yet against solid tumors. Here, we used fluorescent imaging microscopy and ex vivo assays to compare the early functional responses (migration, Ca2+, and cytotoxicity) of CD20 and EGFR CAR T cells upon contact with malignant B cells and carcinoma cells. Our results indicated that CD20 CAR T cells rapidly form productive ICAM-1-dependent conjugates with their targets. By comparison, EGFR CAR T cells only initially interacted with a subset of carcinoma cells located at the periphery of tumor islets. After this initial peripheral activation, EGFR CAR T cells progressively relocated to the center of tumor cell regions. The analysis of this two-step entry process showed that activated CAR T cells triggered the upregulation of ICAM-1 on tumor cells in an IFNγ-dependent pathway. The ICAM-1/LFA-1 interaction interference, through antibody or shRNA blockade, prevented CAR T-cell enrichment in tumor islets. The requirement for IFNγ and ICAM-1 to enable CAR T-cell entry into tumor islets is of significance for improving CAR T-cell therapy in solid tumors.

Potential Patient-Reported Toxicities With Disulfiram Treatment in Late Disseminated Lyme Disease.

Recently, disulfiram has been proposed as a promising treatment for people suffering from persistent symptoms of Lyme Disease. Disulfiram has several distinct molecular targets. The most well-known is alcohol dehydrogenase, a key enzyme for detoxifying the organism after alcohol ingestion. Other targets and modes of action of disulfiram, that may present problematic side effects, are less commonly mentioned. The French Federation against Tick Borne Diseases (French acronym, FFMVT), which associates three main Lyme patient organizations, MDs and PhDs, has recently been alerted to severe and persistent toxic events in a patient suffering from a late disseminated form of Lyme Disease following disulfiram intake. FFMVT reacted by launching a national call to examine whether other patients in France following a similar treatment could be identified, and what benefits, or side effects could be reported. The statements of 16 patients taking disulfiram have been collected and are presented here. Thirteen out of 16 patients reported toxic events, and seven out of 16 reported benefits for at least part of their symptoms. Based on the collected observations, it seems too early to promote disulfiram as a promising new treatment until the reasons underlying the reported toxicities have been explored, and the results of a well-conducted double blind clinical trial published. The importance of taking into account patient-reported outcomes in Lyme Disease is underlined by the present study.

Preclinical murine tumor models: a structural and functional perspective.

The goal of this review is to pinpoint the specific features, including the weaknesses, of various tumor models, and to discuss the reasons why treatments that are efficient in murine tumor models often do not work in clinics. In a detailed comparison of transplanted and spontaneous tumor models, we focus on structure-function relationships in the tumor microenvironment. For instance, the architecture of the vascular tree, which depends on whether tumor cells have gone through epithelial-mesenchymal transition, is determinant for the extension of the spontaneous necrosis, and for the intratumoral localization of the immune infiltrate. Another key point is the model-dependent abundance of TGFß in the tumor, which controls the variable susceptibility of different tumor models to treatments. Grounded in a historical perspective, this review provides a rationale for checking factors that will be key for the transition between preclinical murine models and clinical applications.

Local IFNα enhances the anti-tumoral efficacy of systemic anti-PD1 to prevent tumor relapse.

BACKGROUND: Tumor relapse constitutes a major challenge for anti-tumoral treatments, including immunotherapies. Indeed, most cancer-related deaths occur during the tumor relapse phase. METHODS: We designed a mouse model of tumor relapse in which mice transplanted with E7+ TC1 tumor cells received a single therapeutic vaccination of STxB-E7+IFNα. Unlike the complete regression observed after two vaccinations, such a treatment induced a transient shrinkage of the tumor mass, followed by a rapid tumor outgrowth. To prevent this relapse, we tested the efficacy of a local administration of IFNα together with a systemic therapy with anti-PD1 Ab. The immune response was analyzed during both the tumor regression and relapse phases. RESULTS: We show that, during the regression phase, tumors of mice treated with a single vaccination of STxB-E7 + IFNα harbor fewer activated CD8 T cells and monocytes than tumors doomed to fully regress after two vaccinations. In contrast, the systemic injection of an anti-PD1 Ab combined with the peri-tumoral injection of IFNα in this time frame promotes infiltration of activated CD8 T cells and myeloid cells, which, together, exert a high cytotoxicity in vitro against TC1 cells. Moreover, the IFNα and anti-PD1 Ab combination was found to be more efficient than IFNα or anti-PD1 used alone in preventing tumor relapse and was better able to prolong mice survival. CONCLUSIONS: Together, these results indicate that the local increase of IFNα in combination with an anti-PD1 therapy is an effective way to promote efficient and durable innate and adaptive immune responses preventing tumor relapse.

The Remarkable Plasticity of Macrophages: A Chance to Fight Cancer.

It is well established that tumor-associated macrophages (TAM) found in most advanced tumors have a pro-tumoral role. In this context, TAM limit the activity of tumor-infiltrating lymphocytes (TIL), and a number of mechanisms have been described including a trapping in the stroma, impeding TIL to reach malignant cells. Based on these results, a number of therapeutic approaches have been designed to deplete TAM. However, during tumor regression induced by immunotherapeutic treatments, recent studies revealed that TAM can switch from pro-tumoral to anti-tumoral and actively cooperate with TIL. Here, we will review the two faces of TAM in their interaction with TIL. We will summarize how they can inhibit T cell activities in growing tumors, and how they may also, together with T cells, successfully contribute to tumor eradication after an appropriate stimulation. Finally, we will discuss current promising therapies combining TAM reprogramming with T cell-based immunotherapy.

Blockade of ß-Adrenergic Receptors Improves CD8+ T-cell Priming and Cancer Vaccine Efficacy.

ß-Adrenergic receptor (ß-AR) signaling exerts protumoral effects by acting directly on tumor cells and angiogenesis. In addition, ß-AR expression on immune cells affects their ability to mount antitumor immune responses. However, how ß-AR signaling impinges antitumor immune responses is still unclear. Using a mouse model of vaccine-based immunotherapy, we showed that propranolol, a nonselective ß-blocker, strongly improved the efficacy of an antitumor STxBE7 vaccine by enhancing the frequency of CD8+ T lymphocytes infiltrating the tumor (TIL). However, propranolol had no effect on the reactivity of CD8+ TILs, a result further strengthened by ex vivo experiments showing that these cells were insensitive to adrenaline- or noradrenaline-induced AR signaling. In contrast, naïve CD8+ T-cell activation was strongly inhibited by ß-AR signaling, and the beneficial effect of propranolol mainly occurred during CD8+ T-cell priming in the tumor-draining lymph node. We also demonstrated that the differential sensitivity of naïve CD8+ T cells and CD8+ TILs to ß-AR signaling was linked to a strong downregulation of ß2-AR expression related to their activation status, since in vitro-activated CD8+ T cells behaved similarly to CD8+ TILs. These results revealed that ß-AR signaling suppresses the initial priming phase of antitumor CD8+ T-cell responses, providing a rationale to use clinically available ß-blockers in patients to improve cancer immunotherapies.

TGFß blocks IFNα/ß release and tumor rejection in spontaneous mammary tumors.

Type I interferons (IFN) are being rediscovered as potent anti-tumoral agents. Activation of the STimulator of INterferon Genes (STING) by DMXAA (5,6-dimethylxanthenone-4-acetic acid) can induce strong production of IFNα/ß and rejection of transplanted primary tumors. In the present study, we address whether targeting STING with DMXAA also leads to the regression of spontaneous MMTV-PyMT mammary tumors. We show that these tumors are refractory to DMXAA-induced regression. This is due to a blockade in the phosphorylation of IRF3 and the ensuing IFNα/ß production. Mechanistically, we identify TGFß, which is abundant in spontaneous tumors, as a key molecule limiting this IFN-induced tumor regression by DMXAA. Finally, blocking TGFß restores the production of IFNα by activated MHCII+ tumor-associated macrophages, and enables tumor regression induced by STING activation. On the basis of these findings, we propose that type I IFN-dependent cancer therapies could be greatly improved by combinations including the blockade of TGFß.

The diversity of immunological synapses.

Immunological synapses (ISs) are specialised signalling domains characterised by complex molecular clustering and segregation at the contact site between cells of the immune system. T lymphocytes form different ISs depending on their state of activation and on the antigen-presenting cells with which they interact. The structural features of the various ISs are better established than the functions they carry out. Recent advances point to the importance of taking into account diversity in both the structures and the functions of IS.

Nanoprobe Synthesized by Magnetotactic Bacteria, Detecting Fluorescence Variations under Dissociation of Rhodamine B from Magnetosomes following Temperature, pH Changes, or the Application of Radiation.

We report a method of fabrication of fluorescent magnetosomes, designated as MCR400, in which 400 µM of rhodamine B are introduced in the growth medium of AMB-1 magnetotactic bacteria and fluorescent magnetosomes are then extracted from these bacteria. These fluorescent magnetosomes behave differently from most fluorescent nanoprobes, which often lead to fluorescence losses over time due to photobleaching. Indeed, when MCR400 are heated to 30-90 °C, brought to an acidic pH, or exposed to radiations, we observed that their fluorescence intensity increased. We attributed this behavior to the dissociation of rhodamine B from the magnetosomes. Interestingly, enhanced fluorescence was also observed in vitro when MCR400 were mixed with either primary macrophages or tumor cells (TC1-GFP or RG2-Cells) or in vivo when MCR400 were introduced in rat glioblastoma. We showed that MCR400 internalize in tumor and immune cells (macrophages) leading to enhanced fluorescence, suggesting that fluorescent magnetosomes could be used during cancer treatments such as magnetic hyperthermia to image cells of interest such as immune or tumor cells.

The STING agonist DMXAA triggers a cooperation between T lymphocytes and myeloid cells that leads to tumor regression.

Regressing tumors are usually associated with a large immune infiltrate, but the molecular and cellular interactions that govern a successful anti-tumor immunity remain elusive. Here, we have triggered type I Interferon (IFN) signaling in a breast tumor model (MMTV-PyMT) using 5,6-dimethylxanthenone-4-acetic acid (DMXAA), a ligand of the STimulator of Interferon Genes, STING. The 2 main events rapidly triggered by DMXAA in transplanted PyMT tumors are 1) the disruption of the tumor vasculature, followed by hypoxia and cell death; 2) the release of chemokines. Both events converged to trigger the recruitment of 2 waves of immune cells: a swift, massive recruitment of neutrophils, followed by a delayed rise in monocytes and CD8 T cells in the tumor mass. Depletion experiments in vivo revealed that myeloid cell subsets and T cells need to cooperate to achieve full-blown recruitment and activation at the tumor site and to induce effective secondary cell death leading to tumor regression (Illustration 1). Altogether, our study highlights that the tumor regression induced by the STING agonist DMXAA results from a cascade of events, with an initial vessel destruction followed by several infiltration waves of immune cells which have to cooperate to amplify and sustain the initial effect. We thus provide the first global and detailed kinetic analysis of the anti-tumoral effect of DMXAA and of its different articulated steps.

[The immunological synapse: models facing facts]. / La synapse immunologique : des modèles aux réalités.

The notion of immunological synapse is generally associated to a concentric structure (a core of T cell receptors surrounded by a ring of adhesion molecules) often called "mature synapse". This schematic view has been built on observations corresponding to peculiar experimental conditions: very high antigen concentration presented by surrogate APCs such as lipid bilayers or B lymphoma. These observations have been hastily constituted in a dogma that a "normal" synapse should look like this, should form only in the presence of antigen, and should trigger a "stop" signal that completely immobilizes the T cell. However, when analyzing the interaction between naive T cells and dendritic cells (DC), that are the only antigen-presenting cells able to activate naive T cells, a very different picture emerges. Firstly, T-DC synapses can form in the absence of antigen; therefore antigen recognition is not a prerequisite for synapse formation. Secondly, these antigen-independent synapses are likely to play several roles, including sensitization of T cells for later antigen detection, and delivery of survival signals. Thirdly, in vivo, naive T cells interacting with antigen-laden DC do not fully stop, but start to make transient contacts with DCs for a few minutes, before continuing their exploration. It is only after several hours of this process that T cells eventually immobilize. Fourthly, the structure of the T-DC synapse is clearly multifocal, the two cells interacting through several tens of tight appositions of a few tens of nm in diameter. These numerous tight appositions are reminiscent of the microclusters that have been recently described at the T-bilayer interface. Finally, synaptic signaling is not a transient initial event, but is sustained for hours. In particular, sustained activation of phosphatidylinositol 3-kinase allows the exclusion out of the nucleus of FoxO transcription factors, normally maintaining T cells in a quiescent state.