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Group 2 innate lymphoid cells (ILC2s) are involved in human diseases, such as allergy, atopic dermatitis and nasal polyposis, but their function in human cancer remains unclear. Here we show that, in acute promyelocytic leukaemia (APL), ILC2s are increased and hyper-activated through the interaction of CRTH2 and NKp30 with elevated tumour-derived PGD2 and B7H6, respectively. ILC2s, in turn, activate monocytic myeloid-derived suppressor cells (M-MDSCs) via IL-13 secretion. Upon treating APL with all-trans retinoic acid and achieving complete remission, the levels of PGD2, NKp30, ILC2s, IL-13 and M-MDSCs are restored. Similarly, disruption of this tumour immunosuppressive axis by specifically blocking PGD2, IL-13 and NKp30 partially restores ILC2 and M-MDSC levels and results in increased survival. Thus, using APL as a model, we uncover a tolerogenic pathway that may represent a relevant immunosuppressive, therapeutic targetable, mechanism operating in various human tumour types, as supported by our observations in prostate cancer. Group 2 innate lymphoid cells (ILC2s) modulate inflammatory and allergic responses, but their function in cancer immunity is still unclear. Here the authors show that, in acute promyelocytic leukaemia, tumour-activated ILC2s secrete IL-13 to induce myeloid-derived suppressor cells and support tumour growth.

Group 2 innate lymphoid cells (ILC2s) play a critical role in protection against helminths and in diverse inflammatory diseases by responding to soluble factors such as the alarmin IL-33, that is often overexpressed in cancer. Nonetheless, regulatory factors that dictate ILC2 functions remain poorly studied. Here, we show that peroxisome proliferator-activated receptor gamma (PPARγ) is selectively expressed in ILC2s in humans and in mice, acting as a central functional regulator. Pharmacologic inhibition or genetic deletion of PPARγ in ILC2s significantly impair IL-33-induced Type-2 cytokine production and mitochondrial fitness. Further, PPARγ blockade in ILC2s disrupts their pro-tumoral effect induced by IL-33-secreting cancer cells. Lastly, genetic ablation of PPARγ in ILC2s significantly suppresses tumor growth in vivo. Our findings highlight a crucial role for PPARγ in supporting the IL-33 dependent pro-tumorigenic role of ILC2s and suggest that PPARγ can be considered as a druggable pathway in ILC2s to inhibit their effector functions. Hence, PPARγ targeting might be exploited in cancer immunotherapy and in other ILC2-driven mediated disorders, such as asthma and allergy. Group 2 innate lymphoid cells (ILC2s) are a component of type 2 immune response recently described to be involved in the regulation of anti-tumor immune responses. Here, the authors show that the expression of the peroxisome proliferator-activated receptor γ (PPAPγ) in human and mouse ILC2 sustains type-2 cytokines secretion and support their pro-tumorigenic role in preclinical cancer models.

PD-1/PD-L1 pathway plays a role in inhibiting immune response. Therapeutic antibodies aimed at blocking the PD-1/PD-L1 interaction have entered clinical development and have been approved for a variety of cancers. However, the clinical benefits are reduced to a group of patients. The research in combined therapies, which allow for a greater response, is strongly encouraging. We previously characterized a polyphenol-rich extract from (P2Et) with antitumor activity in both melanoma and breast carcinoma, as well as immunomodulatory activity. We hypothesize that the combined treatment with P2Et and anti-PD-L1 can improve the antitumor response through an additive antitumor effect. We investigated the antitumor and immunomodulatory activity of P2Et and anti-PD-L1 combined therapy in B16-F10 melanoma and 4T1 breast carcinoma. We analyzed tumor growth, hematologic parameters, T cell counts, cytokine expression, and T cell cytotoxicity. In the melanoma model, combined P2Et and anti-PD-L1 therapy has the following effects: decrease in tumor size; increase in the number of activated CD4 and CD8 T cells; decrease in the number of suppressor myeloid cells; increase in PD-L1 expression; decrease in the frequency of CD8 T cell expressing PD-1; improvement in the cytotoxic activity of T cells; and increase in the IFN secretion. In the breast cancer model, P2Et and PD-L1 alone or in combination show antitumor effect with no clear additive effect. This study shows that combined therapy of P2Et and anti-PD-L1 can improve antitumor response in a melanoma model by activating the immune response and neutralizing immunosuppressive mechanisms.

Several distinct innate lymphoid cell (ILC) populations have been recently identified and shown to play a critical role in the immediate immune defense. In the context of tumors, there is evidence to support a dual role for ILCs with pro- or antitumor effects, depending on the ILC subset and the type of cancer. This ambivalent role has been particularly well-described in colorectal cancer models (CRC), but the presence and the evolution of ILCs in the peripheral blood of metastatic CRC (mCRC) patients have not yet been explored. Here, we investigated the distribution of ILC subsets in 96 mCRC patients who were prospectively included in the \"Epitopes-CRC02\" trial. Peripheral blood mononuclear cells (PBMCs) were analyzed by flow cytometry at metastatic diagnosis and after 3-months of treatment. The treatments consisted of Oxaliplatin-based chemotherapies for 76% of the patients or Folfiri (5FU, Irinotecan) chemotherapies for 14% of patients. Compared to healthy donors, the frequency of total ILCs was dramatically increased at metastatic diagnosis. CD56 ILC1-like cells were expanded, whereas ILC2, NCR ILCP and NCR ILCP subsets were decreased. Combined analysis with the systemic anti-telomerase hTERT Th1 CD4 response revealed that patients with low anti-TERT Th1 CD4 responses had the highest frequencies of total ILCs at diagnosis. Of those, 91% had synchronous metastases, and their median progression-free survival was 7.43 months (vs. 9.17 months for the other patients). In these patients, ILC1 and ILC2 were significantly decreased, whereas CD56 ILC1-like cells were significantly increased compared to patients with low frequency of total ILCs and high anti-TERT responses. After treatment, the NCR ILCP were further decreased irrespective of the chemotherapy regimen, whereas the balance between ILC1 and CD56 ILC1-like cells was modulated mainly by the Folfiri regimen in favor of ILC1. Altogether our results describe the effects of different chemotherapies on ILCs in mCRC patients. We also establish for the first time a link between frequency of ILCs and anti-tumor CD4 T cell responses in cancer patients. Thus, our study supports an interest in monitoring ILCs during cancer therapy to possibly identify predictive biomarkers in mCRC.

BackgroundIt has been proposed that polyphenols can be used in the development of new therapies against COVID-19, given their ability to interfere with the adsorption and entrance processes of the virus, thus disrupting viral replication. Seeds from Caesalpinia spinosa , have been traditionally used for the treatment of inflammatory pathologies and respiratory diseases. Our team has obtained an extract called P2Et, rich in polyphenols derived from gallic acid with significant antioxidant activity, and the ability to induce complete autophagy in tumor cells and reduce the systemic inflammatory response in animal models.MethodsIn this work, a phase II multicenter randomized double-blind clinical trial on COVID-19 patients was designed to evaluate the impact of the P2Et treatment on the clinical outcome and the immunological parameters related to the evolution of the disease. The Trial was registered with the number No. NCT04410510*. A complementary study in an animal model of lung fibrosis was carried out to evaluate in situ lung changes after P2Et in vivo administration. The ability of P2Et to inhibit the viral load of murine and human coronaviruses in cellular models was also evaluated.ResultsPatients treated with P2Et were discharged on average after 7.4 days of admission vs. 9.6 days in the placebo group. Although a decrease in proinflammatory cytokines such as G-CSF, IL-15, IL-12, IL-6, IP10, MCP-1, MCP-2 and IL-18 was observed in both groups, P2Et decreased to a greater extent G-CSF, IL-6 and IL-18 among others, which are related to lower recovery of patients in the long term. The frequency of T lymphocytes (LT) CD3+, LT double negative (CD3+CD4-CD8-), NK cells increased in the P2Et group where the population of eosinophils was also significantly reduced. In the murine bleomycin model, P2Et also reduced lung inflammation and fibrosis. P2Et was able to reduce the viral replication of murine and human coronaviruses in vitro , showing its dual antiviral and anti-inflammatory role, key in disease control.ConclusionsTaken together these results suggest that P2Et could be consider as a good co-adjuvant in the treatment of COVID-19.Clinical trail registrationhttps://clinicaltrials.gov/ct2/show/NCT04410510, identifier: NCT04410510.

Innate lymphoid cells type 2 (ILC2s) are key regulators of tissue homeostasis and inflammation. In cancer, ILC2s can exhibit pro-tumoral functions by increasing the myeloid derived suppressor cells (MDSC)/T-cell ratio. Nevertheless, the upstream ILC2 triggers remain poorly defined. Here, we identify nerve growth factor (NGF) as the driver of ILC2 pro-tumoral functions in patients with bladder cancer. We show that ILC2s express the NGF receptor TrkA and respond to NGF by secreting type-2 cytokines. In the tumor microenvironment, NGF-producing mast cells accumulate and activate ILC2s to induce regulatory T cells (Tregs), ultimately fostering tumor growth. In patients, NGF levels inversely correlate with survival in ILC2-rich tumors, underscoring the clinical significance of this axis. In vivo administration of a selective TrkA inhibitor improves survival in orthotopic tumor-bearing female mice and sensitizes them to immune checkpoint blockade (ICB). Overall, we identify NGF as an ILC2 activator that shapes pro-tumoral ILC2 functions. The blockade of TrkA + ILC2s might represent a targetable strategy to improve survival, particularly in ICB-resistant patients.

Chemotherapy faces the problem of chemo-resistance in large part of tumors, leading to the appearance of metastasis difficult to eliminate. Over the past decade an improved understanding of the effect of immunogenic chemotherapy on tumor-host interactions has led to the concept of immunogenic cell death (ICD), a type of cell death capable to convert a tumor into an in situ vaccine through the generation of danger signals, dendritic cells activation an finally breaking tolerance, which leads to the destruction of residual tumor cells. Polyphenols are natural compounds from plants, traditionally used for cancer treatment, that exhibit multiple biological activities including anti-oxidation, anti-angiogenesis and pro-apoptosis, which together may exert potent anti-tumor activity. However, little is known about the mechanism of action of polyphenols. We previously obtained a normalized polyphenol rich fraction from Ceasalpina spinosa (P2Et) that exerted cytotoxic activity on several tumor cell lines. Moreover, P2Et showed anti-tumor activity in the 4T1 transplantable model through ICD induction. Vaccination with P2Et-pretreated 4T1 cells yielded long lasting ex vivo IL-2, TNF-α, IL-4, IL-5, and IFN-γ secreting multifunctional T cells after specific 4T1 cell stimulation. In this work we investigate the activation of the immune system after in vivo P2Et treatment of B16 tumor bearing mice. Analysis of spleen, lymph nodes and tumors shows increase numbers of CD44 high, CD4 and CD8 T cells, as well as NK cells in P2Et treated mice compared to non-treated ones. In addition, in vitro, phagocytosis of P2Et treated tumor cells induce activation of DC, and in vivo P2Et induces recruitment and activation of cross-presenting DCs (CD11c+, CD11b+, Ly6C+ or CD11c+ CD8α+) in spleen and tumors, which could lead to the effective activation of CD8 T cells favoring a better tumor control. In fact, vaccinated mice treated with P2Et cells are able to effectively control the growth of transplanted tumor. Accordingly, we observed that P2Et anti-tumor activity is highly dependent on an intact immune system, as P2Et anti-tumor activity is lost in RAG γc KO immunodeficient mice. In summary, P2Et exert its anti-tumor activity through the activation of the endogenous immune system, playing an important role not only in the destruction of the primary tumor but also in controlling metastasis.