Acute Influenza Infection Promotes Lung Tumor Growth by Reprogramming the Tumor Microenvironment.

One billion people worldwide get flu every year, including patients with non-small cell lung cancer (NSCLC). However, the impact of acute influenza A virus (IAV) infection on the composition of the tumor microenvironment (TME) and the clinical outcome of patients with NSCLC is largely unknown. We set out to understand how IAV load impacts cancer growth and modifies cellular and molecular players in the TME. Herein, we report that IAV can infect both tumor and immune cells, resulting in a long-term protumoral effect in tumor-bearing mice. Mechanistically, IAV impaired tumor-specific T-cell responses, led to the exhaustion of memory CD8+ T cells and induced PD-L1 expression on tumor cells. IAV infection modulated the transcriptomic profile of the TME, fine-tuning it toward immunosuppression, carcinogenesis, and lipid and drug metabolism. Consistent with these data, the transcriptional module induced by IAV infection in tumor cells in tumor-bearing mice was also found in human patients with lung adenocarcinoma and correlated with poor overall survival. In conclusion, we found that IAV infection worsened lung tumor progression by reprogramming the TME toward a more aggressive state.

To Vaccinate or not: Influenza Virus and Lung Cancer Progression.

Influenza virus infection leads to severe and complicated disease, particularly in patients with lung cancer. It alters the tumor microenvironment (TME), which may potentiate lung cancer progression and disrupt responses to antitumoral treatments. Consequently, influenza vaccination and antiviral treatments should be recommended to all patients with lung cancer.

Natural killer cells in the human lung tumor microenvironment display immune inhibitory functions.

BACKGROUND: Natural killer (NK) cells play a crucial role in tumor immunosurveillance through their cytotoxic effector functions and their capacity to interact with other immune cells to build a coordinated antitumor immune response. Emerging data reveal NK cell dysfunction within the tumor microenvironment (TME) through checkpoint inhibitory molecules associated with a regulatory phenotype. OBJECTIVE: We aimed at analyzing the gene expression profile of intratumoral NK cells compared with non-tumorous NK cells, and to characterize their inhibitory function in the TME. METHODS: NK cells were sorted from human lung tumor tissue and compared with non- tumoral distant lungs. RESULTS: In the current study, we identify a unique gene signature of NK cell dysfunction in human non-small cell lung carcinoma (NSCLC). First, transcriptomic analysis reveals significant changes related to migratory pattern with a downregulation of sphingosine-1-phosphate receptor 1 (S1PR1) and CX3C chemokine receptor 1 (CX3CR1) and overexpression of C-X-C chemokine receptor type 5 (CXCR5) and C-X-C chemokine receptor type 6 (CXCR6). Second, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and killer cell lectin like receptor (KLRC1) inhibitory molecules were increased in intratumoral NK cells, and CTLA-4 blockade could partially restore MHC class II level on dendritic cell (DC) that was impaired during the DCs/NK cell cross talk. Finally, NK cell density impacts the positive prognostic value of CD8+ T cells in NSCLC. CONCLUSIONS: These findings demonstrate novel molecular cues associated with NK cell inhibitory functions in NSCLC.

Tight Interplay Between Therapeutic Monoclonal Antibodies and the Tumour Microenvironment in Cancer Therapy.

Therapeutic monoclonal antibodies (mAb) have changed the landscape of cancer therapy. With advances in the understanding of tumour biology and its microenvironment, different categories of mAbs have been developed; a first category is directed against tumour cells themselves, a second one comprises antibodies blocking the formation of neo-vasculature that accompanies tumour development, and, during the last decades, a third new category of immunomodulatory antibodies that target immune cells in the tumour microenvironment rather than cancer cells has emerged. In this chapter, we outline the main mechanisms of action of the different anti-tumour antibodies. We discuss the notion that, rather than passive immunotherapy that solely induces tumour cell killing, mAbs have multifaceted effects on the tumour microenvironment and could, qualitatively and quantitatively, reshape the immune infiltrate. We also discuss bystander effects of mAbs on the tumour microenvironment that should be carefully considered for the design of new therapeutic strategies.

Stimulation with FITC-labeled antigens confers B cells with regulatory properties.

B cells with regulatory properties (Bregs) were identified in human and in mice among different B-cell subsets. Their regulatory properties rely mainly on the production of anti-inflammatory cytokines, in particular IL10, IL-35 and TGFß, and were extensively studied in mouse models of autoimmune and inflammatory diseases. However, the exact nature of the stimulatory signals conferring regulatory properties to B cells is still not clear. We serendipitously observed that fluorescein isothiocyanate (FITC) binds to a significant proportion of naïve mouse B cells. Binding of FITC to the B-cell surface implicated at least in part the B-cell receptor. It triggered IL-10 production and allowed the endocytosis of FITC-coupled antigens followed by their presentation to CD4+ T cells. In particular, B cells incubated with FITC-OVA polarized OTII T cells towards a Tr1/Th2 phenotype in vitro. Further, the adoptive transfer of B cells incubated with FITC-labeled myelin oligodendrocyte glycoprotein peptide protected mice from experimental autoimmune encephalomyelitis, a T-cell-dependent autoimmune model. Together, the data show that FITC-stimulated B cells polarize immune responses towards Tr1/Th2 and acquire immuno-modulatory properties.

Toll-Like Receptors (TLRs) in the Tumor Microenvironment (TME): A Dragon-Like Weapon in a Non-fantasy Game of Thrones.

Toll-like receptors (TLRs) in the tumor microenvironment (TME) are expressed not only in innate and adaptive immune cells but also in stromal cells such as fibroblasts, endothelial cells (EC), and tumor cells. The role of TLR signaling in the TME is complex and controversial due to their wide expression within the TME. Moreover, TLR signaling may culminate in different outcomes depending on the type of tumor, the implicated TLR, the type of TLR ligands, and, most importantly, the main type of cell(s) that are targeted by TLR ligands. Understanding to what extent these complex TLR signals impact on tumor progression merits further investigation, as it can help improve existing anti-cancer treatments or unravel new ones. In most cases, TLR signaling in tumor cells and in immune cells is associated with pro-tumoral and anti-tumoral effects, respectively. A better understanding of the relationship between TLRs and the TME, especially in humans, is required to design better anti-cancer therapies, considering that most current TLR-involved treatments were disappointing in clinical trials.In this chapter, we will discuss the impact of TLR signaling on the hallmarks of cancer, by highlighting their effects in tumor, immune, and stromal cells within the TME. Furthermore, we will discuss how the understanding of the role of TLRs can pave the way to develop new anti-cancer treatments and even predict clinical outcome and chemotherapy efficacy.

[Origin and nature of the neutralizing immune response against therapeutic factor VIII]. / Origine et nature de la réponse immunitaire neutralisante contre le facteur VIII thérapeutique.

The use of therapeutic proteins induces in some patients the appearance of neutralizing antibodies. This is the case of pro-coagulant factor VIII (FVIII) used in patients with hemophilia A. Several parameters related to the protein itself, to the type of pathology or to the patients, condition the immunogenicity of a therapeutic protein. Understanding these parameters would help to anticipate or prevent the development of neutralizing antibodies. In the case of FVIII, we propose that the development of neutralizing antibodies does not result from an unpredicted immune response but rather from the inability of the patient's organism to develop an anti-inflammatory or regulatory response.

TITLE: Origine et nature de la réponse immunitaire neutralisante contre le facteur VIII thérapeutique. ABSTRACT: L'utilisation de protéines thérapeutiques se heurte, chez certains patients, à l'apparition d'anticorps neutralisants. C'est le cas, par exemple, du facteur VIII pro-coagulant qui est utilisé pour traiter les patients atteints d'hémophilie A. Plusieurs paramètres, liés à la protéine elle-même, au type de pathologie ou aux patients, conditionnent l'immunogénicité d'une protéine thérapeutique. Les comprendre permettrait d'anticiper ou de prévenir la survenue d'anticorps neutralisants. Nous proposons dans cette revue de montrer que, dans le cas du facteur VIII, la survenue de ces anticorps neutralisants ne résulte pas d'une réponse immunitaire inopinée, mais plutôt de l'incapacité de l'organisme des patients à développer une réponse anti-inflammatoire ou régulatrice.

Pathogenic immune response to therapeutic factor VIII: exacerbated response or failed induction of tolerance?

Therapeutic factor VIII is highly immunogenic. Despite intensive research in the last decades, the reasons why 5-30% of patients with hemophilia A (of all severities) develop inhibitory anti-factor VIII antibodies (inhibitors) following replacement therapy remain an enigma. Under physiological conditions, endogenous factor VIII is recognized by the immune system. Likewise, numerous observations indicate that, in hemophilia A patients without inhibitors, exogenous therapeutic factor VIII is immunologically assessed and tolerated. A large part of the research on the immunogenicity of therapeutic factor VIII is attempting to identify the 'danger signals' that act as adjuvants to the deleterious anti-factor VIII immune responses. However, several of the inflammatory assaults concomitant to factor VIII administration initially hypothesized as potential sources of danger signals (e.g., bleeding, infection, and vaccination) have been disproved to be such signals. Conversely, recent evidence suggests that cells from inhibitor-negative patients are able to activate anti-inflammatory and tolerogenic mechanisms required to suppress deleterious immune responses, while cells from inhibitor-positive patients are not. Based on the available observations, we propose a model in which all hemophilia A patients develop anti-factor VIII immune responses during replacement therapy irrespective of associated danger signals. We further postulate that the onset of clinically relevant factor VIII inhibitors results from an inability to develop counteractive tolerogenic responses to exogenous factor VIII rather than from an exacerbated activation of the immune system at the time of factor VIII administration. A better understanding of the pathogenesis of neutralizing anti-factor VIII antibodies will have repercussions on the clinical management of patients and highlight new strategies to achieve active immune tolerance to therapeutic factor VIII.

TLR3-Induced Maturation of Murine Dendritic Cells Regulates CTL Responses by Modulating PD-L1 Trafficking.

Targeting TLR3 through formulations of polyI:C is widely studied as an adjuvant in cancer immunotherapy. The efficacy of such targeting has been shown to increase in combination with anti-PD-L1 treatment. Nevertheless, the mechanistic details of the effect of polyI:C on DC maturation and the impact on T-DC interactions upon PD-L1 blockade is largely unknown. Here we found that although DC treatment with polyI:C induced a potent inflammatory response including the production of type I interferon, polyI:C treatment of DCs impaired activation of peptide specific CD8+ T cells mainly due to PD-L1. Interestingly, we found that PD-L1 trafficking to the cell surface is regulated in two waves in polyI:C-treated DCs. One induced upon overnight treatment and a second more rapid one, specific to polyI:C treatment, was induced upon CD40 signaling leading to a further increase in surface PD-L1 in DCs. The polyI:C-induced cell surface PD-L1 reduced the times of contact between DCs and T cells, potentially accounting for limited T cell activation. Our results reveal a novel CD40-dependent regulation of PD-L1 trafficking induced upon TLR3 signaling that dictates its inhibitory activity. These results provide a mechanistic framework to understand the efficacy of anti-PD-L1 cancer immunotherapy combined with TLR agonists.

Critical role for the kinesin KIF3A in the HIV life cycle in primary human macrophages.

Macrophages are long-lived target cells for HIV infection and are considered viral reservoirs. HIV assembly in macrophages occurs in virus-containing compartments (VCCs) in which virions accumulate and are stored. The regulation of the trafficking and release of these VCCs remains unknown. Using high resolution light and electron microscopy of HIV-1-infected primary human macrophages, we show that the spatial distribution of VCCs depended on the microtubule network and that VCC-limiting membrane was closely associated with KIF3A+ microtubules. Silencing KIF3A strongly decreased virus release from HIV-1-infected macrophages, leading to VCC accumulation intracellularly. Time-lapse microscopy further suggested that VCCs and associated KIF3A move together along microtubules. Importantly, KIF3A does not play a role in HIV release from T cells that do not possess VCCs. These results reveal that HIV-1 requires the molecular motor KIF3 to complete its cycle in primary macrophages. Targeting this step may lead to novel strategies to eliminate this viral reservoir.

Physiological induction of regulatory Qa-1-restricted CD8+ T cells triggered by endogenous CD4+ T cell responses.

T cell-dependent autoimmune diseases are characterized by the expansion of T cell clones that recognize immunodominant epitopes on the target antigen. As a consequence, for a given autoimmune disorder, pathogenic T cell clones express T cell receptors with a limited number of variable regions that define antigenic specificity. Qa-1, a MHC class I-like molecule, presents peptides from the variable region of TCRs to Qa-1-restricted CD8+ T cells. The induction of Vß-specific CD8+ T cells has been harnessed in an immunotherapeutic strategy known as the "T cell vaccination" (TCV) that comprises the injection of activated and attenuated CD4+ T cell clones so as to induce protective CD8+ T cells. We hypothesized that Qa-1-restricted CD8+ regulatory T cells could also constitute a physiologic regulatory arm of lymphocyte responses upon expansion of endogenous CD4+ T cells, in the absence of deliberate exogenous T cell vaccination. We immunized mice with two types of antigenic challenges in order to sequentially expand antigen-specific endogenous CD4+ T cells with distinct antigenic specificities but characterized by a common Vß chain in their TCR. The first immunization was performed with a non-self antigen while the second challenge was performed with a myelin-derived peptide known to drive experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. We show that regulatory Vß-specific Qa-1-restricted CD8+ T cells induced during the first endogenous CD4+ T cell responses are able to control the expansion of subsequently mobilized pathogenic autoreactive CD4+ T cells. In conclusion, apart from the immunotherapeutic TCV, Qa-1-restricted specialized CD8+ regulatory T cells can also be induced during endogenous CD4+ T cell responses. At variance with other regulatory T cell subsets, the action of these Qa-1-restricted T cells seems to be restricted to the immediate re-activation of CD4+ T cells.

Immune responses elicited in tertiary lymphoid tissues display distinctive features.

During chronic inflammation, immune effectors progressively organize themselves into a functional tertiary lymphoid tissue (TLT) within the targeted organ. TLT has been observed in a wide range of chronic inflammatory conditions but its pathophysiological significance remains unknown. We used the rat aortic interposition model in which a TLT has been evidenced in the adventitia of chronically rejected allografts one month after transplantation. The immune responses elicited in adventitial TLT and those taking place in spleen and draining lymph nodes (LN) were compared in terms of antibody production, T cell activation and repertoire perturbations. The anti-MHC humoral response was more intense and more diverse in TLT. This difference was associated with an increased percentage of activated CD4+ T cells and a symmetric reduction of regulatory T cell subsets. Moreover, TCR repertoire perturbations in TLT were not only increased and different from the common pattern observed in spleen and LN but also "stochastic," since each recipient displayed a specific pattern. We propose that the abnormal activation of CD4+ T cells promotes the development of an exaggerated pathogenic immune humoral response in TLT. Preliminary findings suggest that this phenomenon i) is due to a defective immune regulation in this non-professional inflammatory-induced lymphoid tissue, and ii) also occurs in human chronically rejected grafts.

Control of T cell reactivation by regulatory Qa-1-restricted CD8+ T cells.

Administration of attenuated pathogenic T cell clones, a procedure known as T cell vaccination, induces CD8+ T cells specific for peptides derived from the Vbeta-chain of the TCR presented by the MHC class Ib molecule, Qa-1 expressed on the vaccine cells. These regulatory CD8+ T cells have the capacity to control the activation of endogenous T cells expressing the same TCR Vbeta-chain as the vaccinating cells. We hypothesized that vaccination with NKT cells could also induce Qa-1-restricted CD8+ T cells that would control NKT cell activation. We tested this hypothesis in a murine model of Con A-induced hepatitis that is induced by NKT cells. Vaccination with NKT cells effectively induced protective Qa-1-restricted CD8+ T cells that prevented hepatitis. Surprisingly, upon vaccination with T cells expressing Vbeta-chains irrelevant to NKT cells, we discovered that the specificity of vaccine-induced Qa-1-restricted CD8+ T cells was not limited to the Vbeta-chain of the vaccinating cells. We further show that these regulatory Qa-1-restricted CD8+ T cells arise spontaneously upon polyclonal activation of T cells in the absence of deliberate T cell vaccination. These experiments provide new insight into a CD8+ T cell compartment that regulates the immediate reactivation of conventional T cells and NKT cells.

TCR stimulation drives cleavage and shedding of the ITIM receptor CD31.

CD31 is a transmembrane molecule endowed with T cell regulatory functions owing to the presence of 2 immunotyrosine-based inhibitory motifs. For reasons not understood, CD31 is lost by a portion of circulating T lymphocytes, which appear prone to uncontrolled activation. In this study, we show that extracellular T cell CD31 comprising Ig-like domains 1 to 5 is cleaved and shed from the surface of human T cells upon activation via their TCR. The shed CD31 can be specifically detected as a soluble, truncated protein in human plasma. CD31 shedding results in the loss of its inhibitory function because the necessary cis-homo-oligomerization of the molecule, triggered by the trans-homophilic engagement of the distal Ig-like domain 1, cannot be established by CD31(shed) cells. However, we show that a juxta-membrane extracellular sequence, comprising part of the domain 6, remains expressed at the surface of CD31(shed) T cells. We also show that the immunosuppressive CD31 peptide aa 551-574 is highly homophilic and possibly acts by homo-oligomerizing with the truncated CD31 remaining after its cleavage and shedding. This peptide is able to sustain phosphorylation of the CD31 ITIM(686) and of SHP2 and to inhibit TCR-induced T cell activation. Finally, systemic administration of the peptide in BALB/c mice efficiently suppresses Ag-induced T cell-mediated immune responses in vivo. We conclude that the loss of T cell regulation caused by CD31 shedding driven by TCR stimulation can be rescued by molecular tools able to engage the truncated juxta-membrane extracellular molecule that remains exposed at the surface of CD31(shed) cells.

Macrophage plasticity in experimental atherosclerosis.

As in human disease, macrophages (MØ) are central players in the development and progression of experimental atherosclerosis. In this study we have evaluated the phenotype of MØ associated with progression of atherosclerosis in the apolipoprotein E (ApoE) knockout (KO) mouse model.We found that bone marrow-derived MØ submitted to M1 and M2 polarization specifically expressed arginase (Arg) II and Arg I, respectively. This distinct arginase expression was used to evaluate the frequency and distribution of M1 and M2 MØ in cross-sections of atherosclerotic plaques of ApoE KO mice. Early lesions were infiltrated by Arg I(+) (M2) MØ. This type of MØ favored the proliferation of smooth muscle cells, in vitro. Arg II(+) (M1) MØ appeared and prevailed in lesions of aged ApoE KO mice and lesion progression was correlated with the dominance of M1 over the M2 MØ phenotype. In order to address whether the M2->M1 switch could be due to a phenotypic switch of the infiltrated cells, we performed in vitro repolarization experiments. We found that fully polarized MØ retained their plasticity since they could revert their phenotype. The analysis of the distribution of Arg I- and Arg II-expressing MØ also argued against a recent recruitment of M1 MØ in the lesion. The combined data therefore suggest that the M2->M1 switch observed in vivo is due to a conversion of cells already present in the lesion. Our study suggests that interventional tools able to revert the MØ infiltrate towards the M2 phenotype may exert an atheroprotective action.

Acquired protein S deficiency leads to obliterative portal venopathy and to compensatory nodular regenerative hyperplasia in HIV-infected patients.

OBJECTIVE: To identify the mechanism of nodular regenerative hyperplasia in HIV-infected patients. DESIGN: Case-control study. SETTING: The hepatology and the infectious disease units of two tertiary care centers in France. PATIENTS: We compared 13 consecutive HIV-positive patients with unexplained nodular regenerative hyperplasia to 16 consecutive HIV-positive patients without nodular regenerative hyperplasia, to eight HIV-negative patients with nodular regenerative hyperplasia from an identified cause and to 10 anonymous healthy blood donors. MAIN OUTCOME MEASURE: Patients and controls were screened for diminished protein S activity and antiprotein S immunoglobulin G (IgG) antibodies. The antiprotein S activity of purified IgG from patients and controls was assessed in a functional test of activation of protein C in which protein S serves as a cofactor. A full liver CT portography was realized on the liver explant of a case patient. RESULTS: The CT portography disclosed diffuse obliterative portal venopathy. Levels of protein S activity were lower among patients with HIV-associated nodular regenerative hyperplasia when compared with HIV-positive patients without nodular regenerative hyperplasia and when compared with HIV-negative patients with nodular regenerative hyperplasia (P < 0.005 for all comparisons). HIV-positive patients with nodular regenerative hyperplasia had significantly higher levels of antiprotein S IgG than HIV-positive patients without nodular regenerative hyperplasia and healthy controls. Purified IgG from patients with HIV-associated nodular regenerative hyperplasia specifically inhibited the protein S-dependent protein C activation. CONCLUSION: Acquired autoimmune protein S paucity and secondary thrombophilia appear to be causes of obliterative portal venopathy and compensatory nodular regenerative hyperplasia in HIV-positive patients.

[Atherogenesis: a dysimmune disease]. / L'athérogenèse: une maladie dysimmunitaire.

The immuno-inflammatory response is central to the development of atherosclerosis. The important players of the adaptive immune system are all involved in this pathologic process. Several antigens have been identified these last years and they are mostly self-molecules that have been modified due to the complex microenvironment that is generated within the diseased artery. Pro-atherogenic autoreactive T cells have been characterized. The presence of auto-reactive natural antibodies has also been confirmed in the lesions. All these, together with the data showing that adoptive transfer of lymphocytes is able to modulate the disease, fulfill the criteria put forth by Witebsky and Rose to define a disease as being autoimmune. However, the complexity of the disease process extends to the immune system. Although T cells are known to be pro-atherogenic, B cells have been clearly shown to be athero-protective. The fine balance between the two extensions of the adaptive immune response is the key to a successful therapeutic approach towards atherosclerosis.

Atheroprotective effect of CD31 receptor globulin through enrichment of circulating regulatory T-cells.

OBJECTIVES: This study was designed to evaluate whether replacing CD31 (PECAM-1) signaling can restore the regulation of lymphocyte activation and improve experimental atherosclerosis. BACKGROUND: Atherosclerosis, the principal cause of myocardial infarction and stroke, is due to the development of a pathogenic immune response within the vascular wall and is aggravated by the reduction of regulatory T-cells. CD31, a transmembrane adhesion molecule with inhibitory signaling functions, is physiologically expressed on blood and vascular resting cells but is lost in pathologic conditions associated with atherosclerosis. METHODS: Replacement therapy with a CD31 receptor globulin (Rg) was delivered by in vivo gene transfer in 6-week-old apolipoprotein E knockout mice (n = 14 per group) every 5 weeks for 6 months. Control groups were treated with a truncated CD31Rg or with vehicle alone. At the end of the study, plaque size and morphology and blood T-cell compartment were analyzed in all mice. RESULTS: Atherosclerotic lesions of CD31Rg-treated mice were smaller (p < 0.01) and showed less neovascularization and intraplaque hemorrhage (p < 0.05) compared with control subjects. Furthermore, circulating regulatory T-cells were increased in vivo (p < 0.01) and showed normal suppressive function on proliferation of conventional T-cells in vitro. Indeed, CD31Rg treatment led to blunted blood T-cell activation (p < 0.05) and reduced T-cell infiltration within plaques (p < 0.01). CONCLUSIONS: Our data suggest that CD31 plays a key role in the regulation of the immune response linked to atherosclerosis. CD31-targeting therapeutic approaches may therefore be envisaged for preventing and treating atherosclerotic diseases.