Targeting Immune Regulatory Networks to Counteract Immune Suppression in Cancer

Novel biomimetic mesoporous silica nanoparticle system possessing targetability and immune synergy facilitates effective solid tumor immuno-chemotherapy

New strategies that enhance both the targetability of chemotherapy drugs and the synergistic effects of chemotherapy and immunotherapy are urgently needed for efficacious solid tumor therapy. In this study, a novel biomimetic nanoparticle system possessing the properties of tumor targeting and immune synergy was designed to meet these requirements. Mesoporous silica nanoparticles loaded with the chemotherapeutic drug doxorubicin (DOX) were coated with cell membranes modified by glycosylphosphatidylinositol (GPI)-anchored anti-HER2 single chain variable fragment (scFv) and the GPI-anchored co-stimulatory molecule CD80 (to promote solid tumor-targeted chemotherapy and cooperated immunotherapy, respectively). The impact of the nanotherapeutic system on both tumor-targeted chemotherapy and cellular immune response was investigated through in vitro and in vivo experiments. The results show that the novel biomimetic therapeutic system effectively promoted antitumor efficiency in vitro and in vivo. In addition, this therapeutic system further enhanced antitumor capacity by increasing CD8⁺ T cell activation and cytokine production and reducing myeloid-derived suppressor cell (MDSC) levels in tumors.

Exosomes derived from myeloid-derived suppressor cells facilitate castration-resistant prostate cancer progression via S100A9/circMID1/miR-506-3p/MID1

Background

Castration-resistant prostate cancer (CRPC) is a major cause of recurrence and mortality among prostate cancer (PCa) patients. Myeloid-derived suppressor cells (MDSCs) regulate castration resistance in PCa. Previously, it was shown that intercellular communication was efficiently mediated by exosomes (Exos), but the role and the mechanism of MDSC-derived Exos in CRPC progression was unclear.

Methods

In this study, the circRNA expression profiles in PC3 cells treated with MDSC-Exo and control cells were investigated using a circRNA microarray.

Results

The data showed that circMID1 (hsa_circ_0007718) expression was elevated in PC3 cells treated with MDSC-Exo. Moreover, high circMID1 expression was found in PCa compared with benign prostatic hyperplasia (BPH) tissues and in CRPC patients compared with hormone sensitive prostate cancer (HSPC) patients. Further studies showed that MDSC-Exo accelerated PCa cell proliferation, migration, and invasion, while circMID1 deficiency inhibited MDSC-Exo-regulated CRPC progression in vitro and in vivo. Mechanistically, MDSC-derived exosomal S100A9 increased circMID1 expression to sponge miR-506-3p, leading to increased MID1 expression and accelerated tumor progression.

Conclusion

Together, our results showed that a S100A9/circMID1/miR-506-3p/MID1 axis existed in MDSC-Exo-regulated CRPC progression, which provided novel insights into MDSC-Exo regulatory mechanisms in CRPC progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03494-5.

Circulating low CD4+/CD8+ ratio is associated with poor prognosis in Waldenstrom macroglobulinemia patients

Waldenstrom macroglobulinemia (WM) is a rare type of non-Hodgkin lymphoma with great heterogeneity, and the data of peripheral blood T-lymphocyte subsets in WM are limited. This study aimed to investigate the clinical correlation and distribution of circulating T-lymphocyte subsets in newly diagnosed WM patients. We retrospectively searched medical records for 86 newly diagnosed WM patients. Comparisons of the absolute CD3⁺ T-lymphocyte count (ACD3C), CD4⁺ T-lymphocyte count (ACD4C), CD8⁺ T-lymphocyte count (ACD8C), and CD4⁺/CD8⁺ T-lymphocyte ratio (CD4⁺/CD8⁺) as continuous parameters in different groups were calculated. Univariate and multivariate analyses were used to assess prognostic factors for overall survival (OS) and progression-free survival (PFS). Young patients (<65 years) had lower ACD8C levels and a higher CD4⁺/CD8⁺ ratio. And the lower level of β2-microglobulin (<3 mg/L) was associated with a higher CD4⁺/CD8⁺ ratio. With a median follow-up of 25 months, the univariate survival analysis showed that CD4⁺/CD8⁺ ratio inversion (CD4⁺/CD8⁺<1.5) was associated with shorter OS and PFS, and multivariate analysis confirmed that inverted CD4⁺/CD8⁺ ratio could be an independent adverse prognostic factor for OS and PFS. Additionally, initial treatment with rituximab or bortezomib significantly improved the PFS and OS of CD4⁺/CD8⁺ inversion patients but did not affect normal CD4⁺/CD8⁺ patients. We show that low circulating CD4⁺/CD8⁺ ratio at diagnosis is an adverse prognostic factor in WM patients and that first-line therapy which included rituximab or bortezomib significantly improved PFS and OS for patients with CD4⁺/CD8⁺ ratio less than 1.5.

P22 virus-like particles as an effective antigen delivery nanoplatform for cancer immunotherapy

As a new strategy for cancer immunotherapy, therapeutic cancer vaccines have been greatly improved in recent years. However, addressing the needs to quickly and efficiently elicit a high-intensity immune response against neoantigen peptides, especially to induce an effective cytotoxic lymphocyte (CTL) reaction, remain challenges in this field. In this study, virus-like particles (VLPs) derived from the phage P22 were adopted to load peptide antigens on the surface, to test whether VLP technology can be used as a platform for efficient peptide antigen delivery by therapeutic cancer vaccines. The B and T epitopes (OVA_B peptide and OVA_T peptide) of ovalbumin (OVA) were used here as model antigens and fused individually at the C terminus of the coat protein (CP), which allowed display on the surface of P22 particles to form two types of vaccine particles (VLP-OVA_B and VLP-OVA_T). Subsequent experiments showed that VLP-OVA_B induced an antibody titer against the peptide antigen as high as 5.0 × 10⁵ and that VLP-OVA_T induced highly effective cross-presentation and then strongly activated a T epitope-specific CTL response. Mouse tumor model experiments showed that VLP-OVA_T could significantly inhibit tumor growth by increasing the proportions of CD4⁺ T cells, CD8⁺ T cells and effector memory T cells (T_EM cells) and lowering the proportion of myeloid-derived suppressor cells (MDSCs) among tumor-infiltrating lymphocytes and splenocytes. Compared with other chemically synthesized nanomaterials, VLPs have obvious advantages as vaccine carriers due to their clear chemical composition, fixed spatial structure, excellent biocompatibility, and relatively high potential for clinical translation. Therefore, this platform may lay a solid foundation for the design and preparation of personalized therapeutic vaccines based on neoantigen peptides.

Approaches to inducing antigen-specific immune tolerance in allergy and autoimmunity: Focus on antigen-presenting cells and extracellular vesicles

Increasing prevalence of allergic and autoimmune diseases urges clinicians and researchers to search for new and efficient treatments. Strategies that activate antigen-specific immune tolerance and simultaneously maintain immune reactivity to all other antigens deserve special attention. Accordingly, antigen-presenting cells (APCs) seem to be the best suited for orchestrating these mechanisms by directing T cell immune responses towards a tolerant subtype. Recent advances in understanding cell-to-cell communication via extracellular vesicles (EVs) make the latter promising candidates for reprogramming APCs towards a tolerant phenotype, and for mediating tolerogenic APC function. Thus, comprehensive studies have been undertaken to describe the interactions of APCs and EVs naturally occurring during immune tolerance induction, as well as to develop EV-based manoeuvres enabling the induction of immune tolerance in an antigen-specific manner. In this review, we summarize the findings of relevant studies, with a special emphasis on future perspectives on their translation to clinical practice.

Precision oncology: myth or reality?

Cancer incidence rates are growing at an alarming pace pressing for the development of innovative personalized approaches to treating this disease. The absence of clinical symptoms in the early stages delays the onset of adequate treatment. Traditional therapies are not always as effective as they should be and do not guarantee long-lasting relapse-free survival. Metastatic cancers pose a particular challenge to healthcare professionals. This review touches upon the immunologic mechanisms underlying the development of malignancies, talks about conventional and innovative therapeutic modalities, such as targeted, gene or specific immunotherapies, and analyzes the literature on the use of different approaches that form a basis for precision oncology.

Systemic treatment of advanced hepatocellular cancer: new hope on the horizon

INTRODUCTION

Hepatocellular carcinoma (HCC) is among the leading causes of cancer-related mortality in the world. The majority of the patients present at an advanced or incurable stage where neither locoregional treatment nor combination treatment of locoregional treatment and systemic therapies is feasible. For decades sorafenib was the only treatment option available for advanced HCC. However, with the advent of new and more effective therapies recently, the overall prognosis of advanced HCC has improved significantly. Areas covered: This review summarises the current systemic treatment options available and future prospects in the management of advanced HCC where patients are not suitable for locoregional treatment. Expert opinion: New effective targeted therapeutics have dramatically changed the treatment landscape for advanced HCC. The incorporation of sequential therapy including sorafenib or lenvatinib as first-line treatment and immunotherapy, regorafenib or cabozantinib as second-line treatment have significantly improved outcomes for patients with advanced HCC. Further development of novel combinations of these new agents and predictive/prognostic biomarkers are being explored. Efforts should also be made to tailor treatment to individual patients based on etiology, clinical and molecular factors.

Is It Possible to Develop Cancer Vaccines to Neoantigens, What Are the Major Challenges, and How Can These Be Overcome? Targeting the Right Antigens in the Right Patients

Recent advances in genomic sequencing and bioinformatics have empowered a revolution in immuno-oncology that has led to numerous unambiguous demonstrations of spontaneous and therapy-induced T-cell responses in patients against a subset of immunogenic tumor-specific somatic mutations known as neoantigens. These findings raise the exciting possibility that patients could be therapeutically treated with personalized vaccines against the mutations expressed by their own tumor. A central challenge for the broader clinical application of this approach will be to define the best antigens to target, to determine the subset of patients most likely to derive significant clinical benefit, and, finally, to discover both the best method of vaccine delivery and the optimal time in the disease course to do so. A growing number of translational immunologists believe that these challenges can be overcome and this perspective will discuss strategies to achieve this.

Immunosuppressive circuits in tumor microenvironment and their influence on cancer treatment efficacy

It has been for long conceived that hallmarks of cancer were intrinsic genetic features driving tumor development, proliferation, and progression, and that targeting such cell-autonomous pathways could be sufficient to achieve therapeutic cancer control. Clinical ex vivo data demonstrated that treatment efficacy often relied on the contribution of host immune responses, hence introducing the concept of tumor microenvironment (TME), namely the existence, along with tumor cells, of non-tumor components that could significantly influence tumor growth and survival. Among the complex network of TME-driving forces, immunity plays a key role and the balance between antitumor and protumor immune responses is a major driver in contrasting or promoting cancer spreading. TME is usually a very immunosuppressed milieu because of a vast array of local alterations contrasting antitumor adaptive immunity, where metabolic changes contribute to cancer dissemination by impairing T cell infiltration and favoring the accrual and activation of regulatory cells. Subcellular structures known as extracellular vesicles then help spreading immunosuppression at systemic levels by distributing genetic and protein tumor repertoire in distant tissues. A major improvement in the knowledge of TME is now pointing the attention back to tumor cells; indeed, recent findings are showing how oncogenic pathways and specific mutations in tumor cells can actually dictate the nature and the function of immune infiltrate. As our information on the reciprocal interactions regulating TME increases, finding a strategy to interfere with TME crosstalk becomes more complex and challenging. Nevertheless, TME interactions represent a promising field for the discovery of novel biomarkers and therapeutic targets for improving treatment efficacy in cancer.

Extracellular vesicles in cancer immune responses: roles of purinergic receptors

Extracellular vesicles (EVs) are nano- to micro-scale membrane-enclosed vesicles that are released from presumably all cell types. Tumor cells and immune cells are prodigious generators of EVs often with competing phenotypes in terms of immune suppression versus immune stimulation. Purinergic receptors, proteins that bind diverse purine nucleotides and nucleosides (ATP, ADP, AMP, adenosine), are widely expressed across tissues and cell types, and are prominent players in immune and tumor cell nucleotide metabolism. The effects of purinergic receptor stimulation or agonism tend to produce inflammatory responses that may aid immune stimulation but may also provoke various immune suppression mechanisms, particularly in the tumor microenvironment. EVs released by cells following receptor stimulation are frequently pro-inflammatory, but often also pro-thrombolytic; these EVs may generate an environment that favors tumor progression at the cost of an effective immune response. Purinergic signaling pathways are becoming more recognized as valuable targets in various therapeutic scenarios, including cancer. It is possible that some of those clinically relevant compounds might also impact EV secretion and/or phenotype, which would hopefully capitalize on the immune stimulatory properties of purinergic signaling while minimizing the immune suppressive consequences. This review covers a relatively understudied area in EV biology, but even so, focuses almost exclusively on the purinergic receptors in a very limited capacity. There is much more to evaluate and incorporate into our understanding of extracellular nucleotides in EV biology, and we hope this work prompts further discovery.

The neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios predict efficacy of platinum-based chemotherapy in patients with metastatic triple negative breast cancer

Platinum salts are active against metastatic triple negative breast cancer (mTNBC), and biomarkers to predict their effectiveness are urgently needed. In recent years, the neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR) have emerged as prognostic biomarkers in many malignancies, but their predictive role in platinum-treated mTNBC patients remains unexplored. We performed a retrospective, single centre study to evaluate the association between baseline NLR or PLR and progression free survival (PFS) of mTNBC patients treated with platinum-based chemotherapy. As a control population, we analysed data from patients with hormone receptor-positive HER2-negative (HR+ HER2−) metastatic breast cancer. Among 57 mTNBC patients treated with the carboplatin-paclitaxel or carboplatin-gemcitabine combination, high NLR and PLR were associated with significantly lower PFS at both univariate and multivariable analysis. Conversely, we did not find a significant association between NLR or PLR and the PFS of 148 patients in the control population. Our findings suggest that the NLR and PLR are predictive of benefit from platinum-containing chemotherapy specifically in mTNBC patients. If validated in larger prospective studies, these easy-to-measure parameters could be combined with emerging predictive biomarkers, such as BRCA 1/2 mutations, to improve the selection of mTNBC patients more likely to benefit from platinum-based chemotherapy.

Immunoregulatory Effects of Myeloid-Derived Suppressor Cell Exosomes in Mouse Model of Autoimmune Alopecia Areata

The treatment of autoimmune diseases still poses a major challenge, frequently relying on non-specific immunosuppressive drugs. Current efforts aim at reestablishing self tolerance using immune cells with suppressive activity like the regulatory T cells (Treg) or the myeloid-derived suppressor cells (MDSC). We have demonstrated therapeutic efficacy of MDSC in mouse Alopecia Areata (AA). In the same AA model, we now asked whether MDSC exosomes (MDSC-Exo) can replace MDSC. MDSC-Exo from bone marrow cells (BMC) cultures of healthy donors could substantially facilitate treatment. With knowledge on MDSC-Exo being limited, their suitability needs to be verified in advance. Protein marker profiles suggest comparability of BMC- to ex vivo collected inflammatory MDSC/MDSC-Exo in mice with a chronic contact dermatitis, which is a therapeutic option in AA. Proteome analyses substantiated a large overlap of function-relevant molecules in MDSC and MDSC-Exo. Furthermore, MDSC-Exo are taken up by T cells, macrophages, NK, and most avidly by Treg and MDSC-Exo uptake exceeds binding of MDSC themselves. In AA mice, MDSC-Exo preferentially target skin-draining lymph nodes and cells in the vicinity of remnant hair follicles. MDSC-Exo uptake is accompanied by a strong increase in Treg, reduced T helper proliferation, mitigated cytotoxic activity, and a slight increase in lymphocyte apoptosis. Repeated MDSC-Exo application in florid AA prevented progression and sufficed for partial hair regrowth. Deep sequencing of lymphocyte mRNA from these mice revealed a significant increase in immunoregulatory mRNA, including FoxP3 and arginase 1. Downregulated mRNA was preferentially engaged in prohibiting T cell hyperreactivity. Taken together, proteome analysis provided important insights into potential MDSC-Exo activities, these Exo preferentially homing into AA-affected organs. Most importantly, changes in leukocyte mRNA seen after treatment of AA mice with MDSC-Exo sustainably supports the strong impact on the adaptive and the non-adaptive immune system, with Treg expansion being a dominant feature. Thus, MDSC-Exo could potentially serve as therapeutic agents in treating AA and other autoimmune diseases.

Janus-Faced Myeloid-Derived Suppressor Cell Exosomes for the Good and the Bad in Cancer and Autoimmune Disease

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells originally described to hamper immune responses in chronic infections. Meanwhile, they are known to be a major obstacle in cancer immunotherapy. On the other hand, MDSC can interfere with allogeneic transplant rejection and may dampen autoreactive T cell activity. Whether MDSC-Exosomes (Exo) can cope with the dangerous and potentially therapeutic activities of MDSC is not yet fully explored. After introducing MDSC and Exo, it will be discussed, whether a blockade of MDSC-Exo could foster the efficacy of immunotherapy in cancer and mitigate tumor progression supporting activities of MDSC. It also will be outlined, whether application of native or tailored MDSC-Exo might prohibit autoimmune disease progression. These considerations are based on the steadily increasing knowledge on Exo composition, their capacity to distribute throughout the organism combined with selectivity of targeting, and the ease to tailor Exo and includes open questions that answers will facilitate optimizing protocols for a MDSC-Exo blockade in cancer as well as for strengthening their therapeutic efficacy in autoimmune disease.

Transfer of in vitro-expanded naïve T cells after lymphodepletion enhances antitumor immunity through the induction of polyclonal antitumor effector T cells

The adoptive transfer of effector T cells combined with lymphodepletion has demonstrated promising antitumor effects in mice and humans, although the availability of tumor-specific T cells is limited. We and others have also demonstrated that the transfer of polyclonal naïve T cells induces tumor-specific effector T cells and enhances antitumor immunity after lymphodepletion. Because tumors have been demonstrated to induce immunosuppressive networks and regulate the function of T cells, obtaining a sufficient number of fully functional naïve T cells that are able to differentiate into tumor-specific effector T cells remains difficult. To establish culture methods to obtain a large number of polyclonal T cells that are capable of differentiating into tumor-specific effector T cells, naïve T cells were activated with anti-CD3 mAbs in vitro. These cells were stimulated with IL-2 and IL-7 for the CD8 subset or with IL-7 and IL-23 for the CD4 subset. Transfer of these hyperexpanded T cells after lymphodepletion showed significant antitumor efficacy, and tumor-specific effector T cells were primed from these expanded T cells in tumor-bearing hosts. Moreover, these ex vivo-expanded T cells maintained T cell receptor diversity and showed long-term persistence of memory against specific tumors. Further analyses revealed that combination therapy consisting of vaccination with dendritic cells that were co-cultured with irradiated whole tumor cells and the transfer of ex vivo-expanded T cells significantly enhanced antitumor immunity. These results indicate that the transfer of ex vivo-expanded polyclonal T cells can be combined with other immunotherapies and augment antitumor effects.

Synthetic melanin bound to subunit vaccine antigens significantly enhances CD8+ T-cell responses

Cytotoxic T-lymphocytes (CTLs) play a key role in immunity against cancer; however, the induction of CTL responses with currently available vaccines remains difficult. Because several reports have suggested that pigmentation and immunity might be functionally linked, we investigated whether melanin can act as an adjuvant in vaccines. Short synthetic peptides (8-35 amino acids long) containing T-cell epitopes were mixed with a solution of L-Dopa, a precursor of melanin. The mixture was then oxidized to generate nanoparticles of melanin-bound peptides. Immunization with melanin-bound peptides efficiently triggered CTL responses in mice, even against self-antigens and at a very low dose of peptides (microgram range). Immunization against a tumor antigen inhibited the growth of established tumors in mice, an effect that was abrogated by the depletion of CD8+ lymphocytes. These results demonstrate the efficacy of melanin as a vaccine adjuvant.