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.

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.

A rationally-engineered IL-2 improves the antitumor effect of anti-CD20 therapy.

Anti-CD20 treatment represents a therapeutic benefit for patients with B-cell lymphomas, although more efficient therapies are needed for refractory or relapsing patients. Among them, the combination of anti-CD20 and IL-2 that induces T cell response has been hampered by the expansion of FoxP3+ Tregs that strongly express the high affinity IL-2 receptor (IL-2R αßγ). We explore here the anti-tumor effect of an anti-CD20 antibody combined with a mutated IL-2 (no-alpha mutein) which has a disrupted affinity for the IL-2R αßγ. We demonstrate that anti-CD20/no-alpha mutein combination significantly augments the survival rate of mice challenged with huCD20+ cells as compared to animals treated with anti-CD20 ± IL-2. Moreover, the combination with no-alpha mutein but not IL-2 provokes an increase of granzyme B and perforin in splenic NK and CD8+ T cells, a reduction of Tregs and an increase in activated macrophages. The former combination also induces a T helper profile different from that obtained with IL-2, with an earlier polarization to Th1 and no increase in Th17. The therapeutic effect of anti-CD20/no-alpha mutein was accompanied by an expansion of peripheral central (TCM) and effector (TEM) memory CD8+ T cell compartments. Last, as opposed to IL-2, no-alpha mutein administered at the beginning of anti-CD20 treatment did not dampen the long-term protection of surviving mice after tumor rechallenge. Thus, this study shows that the combination of anti-tumor antibodies and no-alpha mutein is a promising approach to improve the therapeutic effect of these antibodies by potentiating NK/macrophage-mediated innate immunity and the adaptive T-cell response.

Presence of T cells directed against CD20-derived peptides in healthy individuals and lymphoma patients.

Preclinical and clinical studies have suggested that cancer treatment with antitumor antibodies induces a specific adaptive T cell response. A central role in this process has been attributed to CD4+ T cells, but the relevant T cell epitopes, mostly derived from non-mutated self-antigens, are largely unknown. In this study, we have characterized human CD20-derived epitopes restricted by HLA-DR1, HLA-DR3, HLA-DR4, and HLA-DR7, and investigated whether T cell responses directed against CD20-derived peptides can be elicited in human HLA-DR-transgenic mice and human samples. Based on in vitro binding assays to recombinant human MHC II molecules and on in vivo immunization assays in H-2 KO/HLA-A2+-DR1+ transgenic mice, we have identified 21 MHC II-restricted long peptides derived from intracellular, membrane, or extracellular domains of the human non-mutated CD20 protein that trigger in vitro IFN-γ production by PBMCs and splenocytes from healthy individuals and by PBMCs from follicular lymphoma patients. These CD20-derived MHC II-restricted peptides could serve as a therapeutic tool for improving and/or monitoring anti-CD20 T cell activity in patients treated with rituximab or other anti-CD20 antibodies.

Impact of Depleting Therapeutic Monoclonal Antibodies on the Host Adaptive Immunity: A Bonus or a Malus?

Clinical responses to anti-tumor monoclonal antibody (mAb) treatment have been regarded for many years only as a consequence of the ability of mAbs to destroy tumor cells by innate immune effector mechanisms. More recently, it has also been shown that anti-tumor antibodies can induce a long-lasting anti-tumor adaptive immunity, likely responsible for durable clinical responses, a phenomenon that has been termed the vaccinal effect of antibodies. However, some of these anti-tumor antibodies are directed against molecules expressed both by tumor cells and normal immune cells, in particular lymphocytes, and, hence, can also strongly affect the host adaptive immunity. In addition to a delayed recovery of target cells, lymphocyte depleting-mAb treatments can have dramatic consequences on the adaptive immune cell network, its rebound, and its functional capacities. Thus, in this review, we will not only discuss the mAb-induced vaccinal effect that has emerged from experimental preclinical studies and clinical trials but also the multifaceted impact of lymphocytes-depleting therapeutic antibodies on the host adaptive immunity. We will also discuss some of the molecular and cellular mechanisms of action whereby therapeutic mAbs induce a long-term protective anti-tumor effect and the relationship between the mAb-induced vaccinal effect and the immune response against self-antigens.

Serine/threonine protein phosphatase-mediated control of the peptidoglycan cross-linking L,D-transpeptidase pathway in Enterococcus faecium.

The last step of peptidoglycan polymerization involves two families of unrelated transpeptidases that are the essential targets of ß-lactam antibiotics. D,D-transpeptidases of the penicillin-binding protein (PBP) family are active-site serine enzymes that use pentapeptide precursors and are the main or exclusive cross-linking enzymes in nearly all bacteria. However, peptidoglycan cross-linking is performed mainly by active-site cysteine L,D-transpeptidases that use tetrapeptides in Mycobacterium tuberculosis, Clostridium difficile, and ß-lactam-resistant mutants of Enterococcus faecium. We have investigated reprogramming of the E. faecium peptidoglycan assembly pathway by a switch from pentapeptide to tetrapeptide precursors and bypass of PBPs by L,D-transpeptidase Ldtfm. Mutational alterations of two signal transduction systems were necessary and sufficient for activation of the L,D-transpeptidation pathway, which is essentially cryptic in wild-type strains. The first one is a classical two-component regulatory system, DdcRS, that controls the activity of Ldtfm at the substrate level. As previously described, loss of DdcS phosphatase activity leads to production of the D,D-carboxypeptidase DdcY and conversion of the pentapeptide into the tetrapeptide substrate of Ldtfm. Here we show that full bypass of PBPs by Ldtfm also requires increased Ser/Thr protein phosphorylation resulting from impaired activity of phosphoprotein phosphatase StpA. This enzyme negatively controlled the level of protein phosphorylation both by direct dephosphorylation of target proteins and by dephosphorylation of its cognate kinase Stk. In combination with production of DdcY, increased protein phosphorylation by this eukaryotic-enzyme-like Ser/Thr protein kinase was sufficient for activation of the L,D-transpeptidation pathway in the absence of mutational alteration of peptidoglycan synthesis enzymes. Importance: The mechanism of acquisition of high-level ampicillin resistance involving bypass of the penicillin-binding proteins (PBPs) by L,D-transpeptidase Ldtfm was incompletely understood, as production of tetrapeptide precursors following transcriptional activation of the ddc locus by the DdcRS two-component regulatory system was necessary but not sufficient for full activation of the L,D-transpeptidation pathway. Here, we identified the release of a negative control of Ser/Thr protein phosphorylation mediated by phosphatase StpA as the additional factor essential for ampicillin resistance. Thus, bypass of PBPs by Ldtfm requires the modification of signal transduction regulatory systems without any gain of function by mutational alteration of peptidoglycan biosynthetic enzymes. In contrast, previously characterized mechanisms of antibiotic resistance involve horizontal gene transfer and mutational alteration of drug targets. Activation of the L,D-transpeptidation pathway reported in this study is an unprecedented mechanism of emergence of a new metabolic pathway since it involved the recruitment of preexisting functions following modifications of regulatory circuits.